| blob | 99021a82df4977b179b45db04e3083012c63067a |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2022 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
89 /* Nonzero if we are folding constants inside an initializer or a C++
90 manifestly-constant-evaluated context; zero otherwise.
91 Should be used when folding in initializer enables additional
92 optimizations. */
95 /* Nonzero if we are folding C++ manifestly-constant-evaluated context; zero
96 otherwise.
97 Should be used when certain constructs shouldn't be optimized
98 during folding in that context. */
101 /* The following constants represent a bit based encoding of GCC's
102 comparison operators. This encoding simplifies transformations
103 on relational comparison operators, such as AND and OR. */
121 };
155 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
156 Otherwise, return LOC. */
158 static location_t
160 {
163 }
165 /* Similar to protected_set_expr_location, but never modify x in place,
166 if location can and needs to be set, unshare it. */
170 {
176 {
179 }
181 }
182 \f
183 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
184 division and returns the quotient. Otherwise returns
185 NULL_TREE. */
187 tree
189 {
190 widest_int quo;
197 }
198 \f
199 /* This is nonzero if we should defer warnings about undefined
200 overflow. This facility exists because these warnings are a
201 special case. The code to estimate loop iterations does not want
202 to issue any warnings, since it works with expressions which do not
203 occur in user code. Various bits of cleanup code call fold(), but
204 only use the result if it has certain characteristics (e.g., is a
205 constant); that code only wants to issue a warning if the result is
206 used. */
210 /* If a warning about undefined overflow is deferred, this is the
211 warning. Note that this may cause us to turn two warnings into
212 one, but that is fine since it is sufficient to only give one
213 warning per expression. */
217 /* If a warning about undefined overflow is deferred, this is the
218 level at which the warning should be emitted. */
222 /* Start deferring overflow warnings. We could use a stack here to
223 permit nested calls, but at present it is not necessary. */
225 void
227 {
229 }
231 /* Stop deferring overflow warnings. If there is a pending warning,
232 and ISSUE is true, then issue the warning if appropriate. STMT is
233 the statement with which the warning should be associated (used for
234 location information); STMT may be NULL. CODE is the level of the
235 warning--a warn_strict_overflow_code value. This function will use
236 the smaller of CODE and the deferred code when deciding whether to
237 issue the warning. CODE may be zero to mean to always use the
238 deferred code. */
240 void
242 {
244 location_t locus;
249 {
255 }
266 /* Use the smallest code level when deciding to issue the
267 warning. */
276 else
279 }
281 /* Stop deferring overflow warnings, ignoring any deferred
282 warnings. */
284 void
286 {
288 }
290 /* Whether we are deferring overflow warnings. */
292 bool
294 {
296 }
298 /* This is called when we fold something based on the fact that signed
299 overflow is undefined. */
301 void
303 {
305 {
308 {
311 }
312 }
315 }
316 \f
317 /* Return true if the built-in mathematical function specified by CODE
318 is odd, i.e. -f(x) == f(-x). */
320 bool
322 {
324 {
325 CASE_CFN_ASIN:
326 CASE_CFN_ASINH:
327 CASE_CFN_ATAN:
328 CASE_CFN_ATANH:
329 CASE_CFN_CASIN:
330 CASE_CFN_CASINH:
331 CASE_CFN_CATAN:
332 CASE_CFN_CATANH:
333 CASE_CFN_CBRT:
334 CASE_CFN_CPROJ:
335 CASE_CFN_CSIN:
336 CASE_CFN_CSINH:
337 CASE_CFN_CTAN:
338 CASE_CFN_CTANH:
339 CASE_CFN_ERF:
340 CASE_CFN_LLROUND:
341 CASE_CFN_LROUND:
342 CASE_CFN_ROUND:
343 CASE_CFN_ROUNDEVEN:
344 CASE_CFN_ROUNDEVEN_FN:
345 CASE_CFN_SIN:
346 CASE_CFN_SINH:
347 CASE_CFN_TAN:
348 CASE_CFN_TANH:
349 CASE_CFN_TRUNC:
352 CASE_CFN_LLRINT:
353 CASE_CFN_LRINT:
354 CASE_CFN_NEARBYINT:
355 CASE_CFN_RINT:
360 }
362 }
364 /* Check whether we may negate an integer constant T without causing
365 overflow. */
367 bool
369 {
370 tree type;
379 }
381 /* Determine whether an expression T can be cheaply negated using
382 the function negate_expr without introducing undefined overflow. */
384 static bool
386 {
387 tree type;
396 {
401 /* Check that -CST will not overflow type. */
414 /* We want to canonicalize to positive real constants. Pretend
415 that only negative ones can be easily negated. */
423 {
427 /* Steps don't prevent negation. */
434 }
449 /* -(A + B) -> (-B) - A. */
452 /* -(A + B) -> (-A) - B. */
456 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
465 /* INT_MIN/n * n doesn't overflow while negating one operand it does
466 if n is a (negative) power of two. */
477 /* Fall through. */
490 /* In general we can't negate A in A / B, because if A is INT_MIN and
491 B is not 1 we change the sign of the result. */
495 /* In general we can't negate B in A / B, because if A is INT_MIN and
496 B is 1, we may turn this into INT_MIN / -1 which is undefined
497 and actually traps on some architectures. */
506 /* Negate -((double)float) as (double)(-float). */
508 {
512 }
516 /* Negate -f(x) as f(-x). */
522 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
524 {
528 }
533 }
535 }
537 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
538 simplification is possible.
539 If negate_expr_p would return true for T, NULL_TREE will never be
540 returned. */
542 static tree
544 {
546 tree tem;
549 {
550 /* Convert - (~A) to A + 1. */
574 {
579 }
583 {
584 tree_vector_builder elts;
588 {
593 }
596 }
619 {
620 /* -(A + B) -> (-B) - A. */
622 {
626 }
628 /* -(A + B) -> (-A) - B. */
630 {
634 }
635 }
639 /* - (A - B) -> B - A */
650 /* Fall through. */
654 {
663 }
671 /* In general we can't negate A in A / B, because if A is INT_MIN and
672 B is not 1 we change the sign of the result. */
678 /* In general we can't negate B in A / B, because if A is INT_MIN and
679 B is 1, we may turn this into INT_MIN / -1 which is undefined
680 and actually traps on some architectures. */
692 /* Convert -((double)float) into (double)(-float). */
694 {
698 }
702 /* Negate -f(x) as f(-x). */
705 {
711 }
715 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
717 {
720 {
727 }
728 }
733 }
736 }
738 /* A wrapper for fold_negate_expr_1. */
740 static tree
742 {
749 }
751 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T cannot be
752 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
753 return NULL_TREE. */
755 static tree
757 {
759 location_t loc;
772 }
773 \f
774 /* Split a tree IN into a constant, literal and variable parts that could be
775 combined with CODE to make IN. "constant" means an expression with
776 TREE_CONSTANT but that isn't an actual constant. CODE must be a
777 commutative arithmetic operation. Store the constant part into *CONP,
778 the literal in *LITP and return the variable part. If a part isn't
779 present, set it to null. If the tree does not decompose in this way,
780 return the entire tree as the variable part and the other parts as null.
782 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
783 case, we negate an operand that was subtracted. Except if it is a
784 literal for which we use *MINUS_LITP instead.
786 If NEGATE_P is true, we are negating all of IN, again except a literal
787 for which we use *MINUS_LITP instead. If a variable part is of pointer
788 type, it is negated after converting to TYPE. This prevents us from
789 generating illegal MINUS pointer expression. LOC is the location of
790 the converted variable part.
792 If IN is itself a literal or constant, return it as appropriate.
794 Note that we do not guarantee that any of the three values will be the
795 same type as IN, but they will have the same signedness and mode. */
797 static tree
801 {
809 /* Strip any conversions that don't change the machine mode or signedness. */
818 /* We can associate addition and subtraction together (even
819 though the C standard doesn't say so) for integers because
820 the value is not affected. For reals, the value might be
821 affected, so we can't. */
827 {
833 /* First see if either of the operands is a literal, then a constant. */
846 /* If we haven't dealt with either operand, this is not a case we can
847 decompose. Otherwise, VAR is either of the ones remaining, if any. */
852 else
855 /* Now do any needed negations. */
862 }
867 {
868 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
869 when IN is constant. */
872 }
873 else
877 {
890 }
900 }
902 /* Re-associate trees split by the above function. T1 and T2 are
903 either expressions to associate or null. Return the new
904 expression, if any. LOC is the location of the new expression. If
905 we build an operation, do it in TYPE and with CODE. */
907 static tree
909 {
911 {
914 }
918 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
919 try to fold this since we will have infinite recursion. But do
920 deal with any NEGATE_EXPRs. */
924 {
926 {
939 }
941 {
944 }
948 }
952 }
953 \f
954 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
955 for use in int_const_binop, size_binop and size_diffop. */
957 static bool
959 {
966 {
975 }
980 }
982 /* Combine two wide ints ARG1 and ARG2 under operation CODE to produce
983 a new constant in RES. Return FALSE if we don't know how to
984 evaluate CODE at compile-time. */
986 bool
990 {
991 wide_int tmp;
994 {
1016 /* It's unclear from the C standard whether shifts can overflow.
1017 The following code ignores overflow; perhaps a C standard
1018 interpretation ruling is needed. */
1025 {
1029 else
1031 }
1032 else
1037 else
1116 }
1118 }
1120 /* Combine two poly int's ARG1 and ARG2 under operation CODE to
1121 produce a new constant in RES. Return FALSE if we don't know how
1122 to evaluate CODE at compile-time. */
1124 static bool
1128 {
1132 {
1150 else
1157 else
1170 }
1172 }
1174 /* Combine two integer constants ARG1 and ARG2 under operation CODE to
1175 produce a new constant. Return NULL_TREE if we don't know how to
1176 evaluate CODE at compile-time. */
1178 tree
1181 {
1182 poly_wide_int poly_res;
1188 {
1194 }
1203 }
1205 /* Return true if binary operation OP distributes over addition in operand
1206 OPNO, with the other operand being held constant. OPNO counts from 1. */
1208 static bool
1210 {
1212 {
1223 }
1224 }
1226 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1227 constant. We assume ARG1 and ARG2 have the same data type, or at least
1228 are the same kind of constant and the same machine mode. Return zero if
1229 combining the constants is not allowed in the current operating mode. */
1231 static tree
1233 {
1234 /* Sanity check for the recursive cases. */
1242 {
1248 }
1251 {
1252 machine_mode mode;
1253 REAL_VALUE_TYPE d1;
1254 REAL_VALUE_TYPE d2;
1255 REAL_VALUE_TYPE value;
1256 REAL_VALUE_TYPE result;
1260 /* The following codes are handled by real_arithmetic. */
1262 {
1273 }
1281 /* Don't perform operation if we honor signaling NaNs and
1282 either operand is a signaling NaN. */
1288 /* Don't perform operation if it would raise a division
1289 by zero exception. */
1295 /* If either operand is a NaN, just return it. Otherwise, set up
1296 for floating-point trap; we return an overflow. */
1298 {
1299 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1300 is off. */
1304 }
1306 {
1307 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1308 is off. */
1312 }
1317 /* Don't constant fold this floating point operation if
1318 both operands are not NaN but the result is NaN, and
1319 flag_trapping_math. Such operations should raise an
1320 invalid operation exception. */
1328 /* Don't constant fold this floating point operation if
1329 the result has overflowed and flag_trapping_math. */
1337 /* Don't constant fold this floating point operation if the
1338 result may dependent upon the run-time rounding mode and
1339 flag_rounding_math is set, or if GCC's software emulation
1340 is unable to accurately represent the result. */
1350 }
1353 {
1354 FIXED_VALUE_TYPE f1;
1355 FIXED_VALUE_TYPE f2;
1356 FIXED_VALUE_TYPE result;
1361 /* The following codes are handled by fixed_arithmetic. */
1363 {
1375 {
1382 }
1387 }
1394 /* Propagate overflow flags. */
1398 }
1401 {
1410 {
1421 mpc_mul);
1435 mpc_div);
1436 /* Fallthru. */
1442 {
1443 /* Keep this algorithm in sync with
1444 tree-complex.cc:expand_complex_div_straight().
1446 Expand complex division to scalars, straightforward algorithm.
1447 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1448 t = br*br + bi*bi
1449 */
1450 tree magsquared
1454 tree t1
1458 tree t2
1465 }
1466 else
1467 {
1468 /* Keep this algorithm in sync with
1469 tree-complex.cc:expand_complex_div_wide().
1471 Expand complex division to scalars, modified algorithm to minimize
1472 overflow with wide input ranges. */
1478 {
1479 /* In the TRUE branch, we compute
1480 ratio = br/bi;
1481 div = (br * ratio) + bi;
1482 tr = (ar * ratio) + ai;
1483 ti = (ai * ratio) - ar;
1484 tr = tr / div;
1485 ti = ti / div; */
1496 }
1497 else
1498 {
1499 /* In the FALSE branch, we compute
1500 ratio = d/c;
1501 divisor = (d * ratio) + c;
1502 tr = (b * ratio) + a;
1503 ti = b - (a * ratio);
1504 tr = tr / div;
1505 ti = ti / div; */
1517 }
1518 }
1523 }
1527 }
1533 {
1538 /* We can operate directly on the encoding if:
1540 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1541 implies
1542 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1544 Addition and subtraction are the supported operators
1545 for which this is true. */
1548 /* We can operate directly on stepped encodings if:
1550 a3 - a2 == a2 - a1
1551 implies:
1552 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1554 which is true if (x -> x op c) distributes over addition. */
1556 else
1557 /* Similarly in reverse. */
1559 tree_vector_builder elts;
1564 {
1570 /* It is possible that const_binop cannot handle the given
1571 code and return NULL_TREE */
1575 }
1578 }
1580 /* Shifts allow a scalar offset for a vector. */
1583 {
1586 tree_vector_builder elts;
1591 {
1596 /* It is possible that const_binop cannot handle the given
1597 code and return NULL_TREE. */
1601 }
1604 }
1606 }
1608 /* Overload that adds a TYPE parameter to be able to dispatch
1609 to fold_relational_const. */
1611 tree
1613 {
1617 /* ??? Until we make the const_binop worker take the type of the
1618 result as argument put those cases that need it here. */
1620 {
1637 {
1642 }
1648 {
1664 {
1669 ? NOP_EXPR
1676 }
1679 }
1685 {
1708 {
1721 }
1724 }
1727 }
1732 /* Make sure type and arg0 have the same saturating flag. */
1737 }
1739 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1740 Return zero if computing the constants is not possible. */
1742 tree
1744 {
1745 /* Don't perform the operation, other than NEGATE and ABS, if
1746 flag_signaling_nans is on and the operand is a signaling NaN. */
1756 {
1757 CASE_CONVERT:
1764 /* If the source address is 0, and the source address space
1765 cannot have a valid object at 0, fold to dest type null. */
1776 {
1777 /* Can't call fold_negate_const directly here as that doesn't
1778 handle all cases and we might not be able to negate some
1779 constants. */
1784 }
1794 {
1798 }
1806 /* Perform BIT_NOT_EXPR on each element individually. */
1808 {
1809 tree elem;
1811 /* This can cope with stepped encodings because ~x == -1 - x. */
1812 tree_vector_builder elements;
1816 {
1822 }
1825 }
1849 {
1872 else
1877 {
1883 }
1886 }
1895 }
1898 }
1900 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1901 indicates which particular sizetype to create. */
1903 tree
1905 {
1907 }
1908 \f
1909 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1910 is a tree code. The type of the result is taken from the operands.
1911 Both must be equivalent integer types, ala int_binop_types_match_p.
1912 If the operands are constant, so is the result. */
1914 tree
1916 {
1925 /* Handle the special case of two poly_int constants faster. */
1927 {
1928 /* And some specific cases even faster than that. */
1930 {
1937 }
1939 {
1943 }
1945 {
1949 }
1951 /* Handle general case of two integer constants. For sizetype
1952 constant calculations we always want to know about overflow,
1953 even in the unsigned case. */
1957 }
1960 }
1962 /* Given two values, either both of sizetype or both of bitsizetype,
1963 compute the difference between the two values. Return the value
1964 in signed type corresponding to the type of the operands. */
1966 tree
1968 {
1970 tree ctype;
1975 /* If the type is already signed, just do the simple thing. */
1983 else
1986 /* If either operand is not a constant, do the conversions to the signed
1987 type and subtract. The hardware will do the right thing with any
1988 overflow in the subtraction. */
1994 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1995 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1996 overflow) and negate (which can't either). Special-case a result
1997 of zero while we're here. */
2003 else
2007 MINUS_EXPR,
2009 }
2010 \f
2011 /* A subroutine of fold_convert_const handling conversions of an
2012 INTEGER_CST to another integer type. */
2014 static tree
2016 {
2017 /* Given an integer constant, make new constant with new type,
2018 appropriately sign-extended or truncated. Use widest_int
2019 so that any extension is done according ARG1's type. */
2023 }
2025 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2026 to an integer type. */
2028 static tree
2030 {
2032 tree t;
2034 /* The following code implements the floating point to integer
2035 conversion rules required by the Java Language Specification,
2036 that IEEE NaNs are mapped to zero and values that overflow
2037 the target precision saturate, i.e. values greater than
2038 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2039 are mapped to INT_MIN. These semantics are allowed by the
2040 C and C++ standards that simply state that the behavior of
2041 FP-to-integer conversion is unspecified upon overflow. */
2043 wide_int val;
2044 REAL_VALUE_TYPE r;
2048 {
2055 }
2057 /* If R is NaN, return zero and show we have an overflow. */
2059 {
2062 }
2064 /* See if R is less than the lower bound or greater than the
2065 upper bound. */
2068 {
2072 {
2075 }
2076 }
2079 {
2082 {
2085 {
2088 }
2089 }
2090 }
2097 }
2099 /* A subroutine of fold_convert_const handling conversions of a
2100 FIXED_CST to an integer type. */
2102 static tree
2104 {
2105 tree t;
2107 scalar_mode mode;
2109 /* Right shift FIXED_CST to temp by fbit. */
2113 {
2115 HOST_BITS_PER_DOUBLE_INT,
2118 /* Left shift temp to temp_trunc by fbit. */
2120 HOST_BITS_PER_DOUBLE_INT,
2122 }
2123 else
2124 {
2127 }
2129 /* If FIXED_CST is negative, we need to round the value toward 0.
2130 By checking if the fractional bits are not zero to add 1 to temp. */
2136 /* Given a fixed-point constant, make new constant with new type,
2137 appropriately sign-extended or truncated. */
2145 }
2147 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2148 to another floating point type. */
2150 static tree
2152 {
2153 REAL_VALUE_TYPE value;
2154 tree t;
2156 /* Don't perform the operation if flag_signaling_nans is on
2157 and the operand is a signaling NaN. */
2162 /* With flag_rounding_math we should respect the current rounding mode
2163 unless the conversion is exact. */
2171 /* If converting an infinity or NAN to a representation that doesn't
2172 have one, set the overflow bit so that we can produce some kind of
2173 error message at the appropriate point if necessary. It's not the
2174 most user-friendly message, but it's better than nothing. */
2181 /* Regular overflow, conversion produced an infinity in a mode that
2182 can't represent them. */
2187 else
2190 }
2192 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2193 to a floating point type. */
2195 static tree
2197 {
2198 REAL_VALUE_TYPE value;
2199 tree t;
2207 }
2209 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2210 to another fixed-point type. */
2212 static tree
2214 {
2215 FIXED_VALUE_TYPE value;
2216 tree t;
2223 /* Propagate overflow flags. */
2227 }
2229 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2230 to a fixed-point type. */
2232 static tree
2234 {
2235 FIXED_VALUE_TYPE value;
2236 tree t;
2238 double_int di;
2245 else
2253 /* Propagate overflow flags. */
2257 }
2259 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2260 to a fixed-point type. */
2262 static tree
2264 {
2265 FIXED_VALUE_TYPE value;
2266 tree t;
2274 /* Propagate overflow flags. */
2278 }
2280 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2281 type TYPE. If no simplification can be done return NULL_TREE. */
2283 static tree
2285 {
2290 /* We can't widen types, since the runtime value could overflow the
2291 original type before being extended to the new type. */
2302 {
2309 }
2311 {
2313 {
2315 /* Avoid the folding if flag_rounding_math is on and the
2316 conversion is not exact. */
2318 {
2324 }
2326 }
2331 }
2333 {
2340 }
2342 {
2345 {
2348 /* We can't handle steps directly when extending, since the
2349 values need to wrap at the original precision first. */
2350 bool step_ok_p
2354 tree_vector_builder v;
2359 {
2365 }
2367 }
2368 }
2370 }
2372 /* Construct a vector of zero elements of vector type TYPE. */
2374 static tree
2376 {
2377 tree t;
2381 }
2383 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2385 bool
2387 {
2402 {
2424 }
2425 }
2427 /* Convert expression ARG to type TYPE. Used by the middle-end for
2428 simple conversions in preference to calling the front-end's convert. */
2430 tree
2432 {
2434 tree tem;
2445 {
2448 /* Handle conversions between pointers to different address spaces. */
2453 /* fall through */
2458 {
2462 }
2476 {
2480 }
2482 {
2486 }
2488 {
2492 }
2495 {
2513 }
2518 {
2522 }
2525 {
2539 }
2543 {
2552 integer_zero_node));
2554 {
2558 {
2564 }
2572 }
2576 }
2594 }
2595 fold_convert_exit:
2598 }
2599 \f
2600 /* Return false if expr can be assumed not to be an lvalue, true
2601 otherwise. */
2603 static bool
2605 {
2606 /* We only need to wrap lvalue tree codes. */
2608 {
2640 /* Assume the worst for front-end tree codes. */
2644 }
2647 }
2649 /* Return an expr equal to X but certainly not valid as an lvalue. */
2651 tree
2653 {
2654 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2655 us. */
2662 }
2663 \f
2664 /* Given a tree comparison code, return the code that is the logical inverse.
2665 It is generally not safe to do this for floating-point comparisons, except
2666 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2667 ERROR_MARK in this case. */
2669 enum tree_code
2671 {
2677 {
2708 }
2709 }
2711 /* Similar, but return the comparison that results if the operands are
2712 swapped. This is safe for floating-point. */
2714 enum tree_code
2716 {
2718 {
2744 }
2745 }
2748 /* Convert a comparison tree code from an enum tree_code representation
2749 into a compcode bit-based encoding. This function is the inverse of
2750 compcode_to_comparison. */
2752 static enum comparison_code
2754 {
2756 {
2787 }
2788 }
2790 /* Convert a compcode bit-based encoding of a comparison operator back
2791 to GCC's enum tree_code representation. This function is the
2792 inverse of comparison_to_compcode. */
2794 static enum tree_code
2796 {
2798 {
2829 }
2830 }
2832 /* Return true if COND1 tests the opposite condition of COND2. */
2834 bool
2836 {
2839 && (invert_tree_comparison
2846 }
2848 /* Return a tree for the comparison which is the combination of
2849 doing the AND or OR (depending on CODE) of the two operations LCODE
2850 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2851 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2852 if this makes the transformation invalid. */
2854 tree
2859 {
2866 {
2877 }
2880 {
2881 /* Eliminate unordered comparisons, as well as LTGT and ORD
2882 which are not used unless the mode has NaNs. */
2888 }
2890 {
2891 /* Check that the original operation and the optimized ones will trap
2892 under the same condition. */
2903 /* In a short-circuited boolean expression the LHS might be
2904 such that the RHS, if evaluated, will never trap. For
2905 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2906 if neither x nor y is NaN. (This is a mixed blessing: for
2907 example, the expression above will never trap, hence
2908 optimizing it to x < y would be invalid). */
2913 /* If the comparison was short-circuited, and only the RHS
2914 trapped, we may now generate a spurious trap. */
2919 /* If we changed the conditions that cause a trap, we lose. */
2922 }
2928 else
2929 {
2934 }
2935 }
2936 \f
2937 /* Return nonzero if two operands (typically of the same tree node)
2938 are necessarily equal. FLAGS modifies behavior as follows:
2940 If OEP_ONLY_CONST is set, only return nonzero for constants.
2941 This function tests whether the operands are indistinguishable;
2942 it does not test whether they are equal using C's == operation.
2943 The distinction is important for IEEE floating point, because
2944 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2945 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2947 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2948 even though it may hold multiple values during a function.
2949 This is because a GCC tree node guarantees that nothing else is
2950 executed between the evaluation of its "operands" (which may often
2951 be evaluated in arbitrary order). Hence if the operands themselves
2952 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2953 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2954 unset means assuming isochronic (or instantaneous) tree equivalence.
2955 Unless comparing arbitrary expression trees, such as from different
2956 statements, this flag can usually be left unset.
2958 If OEP_PURE_SAME is set, then pure functions with identical arguments
2959 are considered the same. It is used when the caller has other ways
2960 to ensure that global memory is unchanged in between.
2962 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2963 not values of expressions.
2965 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2966 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2968 If OEP_BITWISE is set, then require the values to be bitwise identical
2969 rather than simply numerically equal. Do not take advantage of things
2970 like math-related flags or undefined behavior; only return true for
2971 values that are provably bitwise identical in all circumstances.
2973 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2974 any operand with side effect. This is unnecesarily conservative in the
2975 case we know that arg0 and arg1 are in disjoint code paths (such as in
2976 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2977 addresses with TREE_CONSTANT flag set so we know that &var == &var
2978 even if var is volatile. */
2980 bool
2983 {
2991 /* If either is ERROR_MARK, they aren't equal. */
2997 /* Similar, if either does not have a type (like a template id),
2998 they aren't equal. */
3002 /* Bitwise identity makes no sense if the values have different layouts. */
3007 /* We cannot consider pointers to different address space equal. */
3014 /* Check equality of integer constants before bailing out due to
3015 precision differences. */
3017 {
3018 /* Address of INTEGER_CST is not defined; check that we did not forget
3019 to drop the OEP_ADDRESS_OF flags. */
3022 }
3025 {
3026 /* If both types don't have the same signedness, then we can't consider
3027 them equal. We must check this before the STRIP_NOPS calls
3028 because they may change the signedness of the arguments. As pointers
3029 strictly don't have a signedness, require either two pointers or
3030 two non-pointers as well. */
3036 /* If both types don't have the same precision, then it is not safe
3037 to strip NOPs. */
3044 }
3045 #if 0
3046 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
3047 sanity check once the issue is solved. */
3048 else
3049 /* Addresses of conversions and SSA_NAMEs (and many other things)
3050 are not defined. Check that we did not forget to drop the
3051 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3054 #endif
3056 /* In case both args are comparisons but with different comparison
3057 code, try to swap the comparison operands of one arg to produce
3058 a match and compare that variant. */
3062 {
3070 }
3073 {
3074 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3076 ;
3078 {
3079 /* If we are interested in comparing addresses ignore
3080 MEM_REF wrappings of the base that can appear just for
3081 TBAA reasons. */
3095 }
3096 else
3098 }
3100 /* When not checking adddresses, this is needed for conversions and for
3101 COMPONENT_REF. Might as well play it safe and always test this. */
3108 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3109 We don't care about side effects in that case because the SAVE_EXPR
3110 takes care of that for us. In all other cases, two expressions are
3111 equal if they have no side effects. If we have two identical
3112 expressions with side effects that should be treated the same due
3113 to the only side effects being identical SAVE_EXPR's, that will
3114 be detected in the recursive calls below.
3115 If we are taking an invariant address of two identical objects
3116 they are necessarily equal as well. */
3123 /* Next handle constant cases, those for which we can return 1 even
3124 if ONLY_CONST is set. */
3127 {
3140 {
3141 /* If we do not distinguish between signed and unsigned zero,
3142 consider them equal. */
3145 }
3149 {
3164 }
3168 flags)
3170 flags));
3181 flags | OEP_ADDRESS_OF
3184 /* In GIMPLE empty constructors are allowed in initializers of
3185 aggregates. */
3189 }
3191 /* Don't handle more cases for OEP_BITWISE, since we can't guarantee that
3192 two instances of undefined behavior will give identical results. */
3196 /* Define macros to test an operand from arg0 and arg1 for equality and a
3197 variant that allows null and views null as being different from any
3198 non-null value. In the latter case, if either is null, the both
3199 must be; otherwise, do the normal comparison. */
3200 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3201 TREE_OPERAND (arg1, N), flags)
3203 #define OP_SAME_WITH_NULL(N) \
3204 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3205 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3208 {
3210 /* Two conversions are equal only if signedness and modes match. */
3212 {
3213 CASE_CONVERT:
3221 }
3231 /* For commutative ops, allow the other order. */
3239 /* If either of the pointer (or reference) expressions we are
3240 dereferencing contain a side effect, these cannot be equal,
3241 but their addresses can be. */
3248 {
3251 {
3255 /* Verify that the access types are compatible. */
3259 }
3264 /* Require the same offset. */
3270 /* Fallthru. */
3278 {
3279 /* Require equal access sizes */
3285 flags)))
3287 /* Verify that access happens in similar types. */
3290 /* Verify that accesses are TBAA compatible. */
3299 /* Verify that alignment is compatible. */
3303 }
3306 /* TARGET_MEM_REF require equal extra operands. */
3317 /* Compare the array index by value if it is constant first as we
3318 may have different types but same value here. */
3324 /* Compare low bound and element size as with OEP_ADDRESS_OF
3325 we have to account for the offset of the ref. */
3330 array_ref_low_bound
3334 array_ref_element_size
3336 flags))));
3339 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3340 may be NULL when we're called to compare MEM_EXPRs. */
3343 {
3346 /* Most of time we only need to compare FIELD_DECLs for equality.
3347 However when determining address look into actual offsets.
3348 These may match for unions and unshared record types. */
3351 {
3354 {
3361 /* Non-FIELD_DECL operands can appear in C++ templates. */
3368 flags))
3370 }
3371 else
3373 }
3374 }
3385 }
3389 {
3391 /* Be sure we pass right ADDRESS_OF flag. */
3408 /* The multiplcation operands are commutative. */
3409 /* FALLTHRU */
3417 /* Otherwise take into account this is a commutative operation. */
3430 /* BIT_INSERT_EXPR has an implict operand as the type precision
3431 of op1. Need to check to make sure they are the same. */
3437 /* FALLTHRU */
3462 /* Virtual table reference. */
3474 {
3479 }
3484 }
3488 {
3492 /* If not both CALL_EXPRs are either internal or normal function
3493 functions, then they are not equal. */
3496 {
3497 /* If the CALL_EXPRs call different internal functions, then they
3498 are not equal. */
3501 }
3502 else
3503 {
3504 /* If the CALL_EXPRs call different functions, then they are not
3505 equal. */
3507 flags))
3509 }
3511 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3512 {
3516 else
3520 }
3522 /* Now see if all the arguments are the same. */
3523 {
3534 /* If we get here and both argument lists are exhausted
3535 then the CALL_EXPRs are equal. */
3537 }
3540 }
3543 /* Consider __builtin_sqrt equal to sqrt. */
3553 {
3554 /* Consider decls with the same name equal. The caller needs
3555 to make sure they refer to the same entity (such as a function
3556 formal parameter). */
3562 }
3567 {
3571 /* In GIMPLE constructors are used only to build vectors from
3572 elements. Individual elements in the constructor must be
3573 indexed in increasing order and form an initial sequence.
3575 We make no effort to compare constructors in generic.
3576 (see sem_variable::equals in ipa-icf which can do so for
3577 constants). */
3582 /* Be sure that vectors constructed have the same representation.
3583 We only tested element precision and modes to match.
3584 Vectors may be BLKmode and thus also check that the number of
3585 parts match. */
3598 {
3603 /* In GIMPLE the indexes can be either NULL or matching i.
3604 Double check this so we won't get false
3605 positives for GENERIC. */
3613 }
3615 }
3618 {
3619 /* Compare the STATEMENT_LISTs. */
3625 {
3626 /* The lists don't have the same number of statements. */
3632 flags & (OEP_LEXICOGRAPHIC
3635 }
3636 }
3641 {
3652 }
3656 }
3658 #undef OP_SAME
3659 #undef OP_SAME_WITH_NULL
3660 }
3662 /* Generate a hash value for an expression. This can be used iteratively
3663 by passing a previous result as the HSTATE argument. */
3665 void
3668 {
3674 {
3677 }
3687 {
3688 /* Alas, constants aren't shared, so we can't rely on pointer
3689 identity. */
3699 {
3703 else
3707 }
3709 {
3713 }
3723 {
3730 }
3732 /* We can just compare by pointer. */
3736 /* The node itself doesn't matter. */
3740 /* Ignore. */
3743 /* A list of expressions, for a CALL_EXPR or as the elements of a
3744 VECTOR_CST. */
3749 {
3755 {
3756 /* In GIMPLE the indexes can be either NULL or matching i. */
3761 }
3763 }
3765 {
3766 tree_stmt_iterator i;
3771 }
3780 /* When referring to a built-in FUNCTION_DECL, use the __builtin__ form.
3781 Otherwise nodes that compare equal according to operand_equal_p might
3782 get different hash codes. However, don't do this for machine specific
3783 or front end builtins, since the function code is overloaded in those
3784 cases. */
3787 {
3790 }
3791 /* FALL THROUGH */
3794 {
3798 }
3802 {
3803 /* DECL's have a unique ID */
3805 }
3807 {
3808 /* For comparisons that can be swapped, use the lower
3809 tree code. */
3816 }
3818 {
3819 /* NOP_EXPR and CONVERT_EXPR are considered equal by
3820 operand_equal_p. */
3824 /* Don't hash the type, that can lead to having nodes which
3825 compare equal according to operand_equal_p, but which
3826 have different hash codes. Make sure to include signedness
3827 in the hash computation. */
3830 }
3831 /* For OEP_ADDRESS_OF, hash MEM_EXPR[&decl, 0] the same as decl. */
3839 /* Don't ICE on FE specific trees, or their arguments etc.
3840 during operand_equal_p hash verification. */
3843 else
3844 {
3850 {
3866 {
3871 else
3872 {
3878 }
3880 }
3894 {
3895 /* The multiplication operands are commutative. */
3902 }
3910 /* For TARGET_EXPR, just hash on the TARGET_EXPR_SLOT.
3911 Usually different TARGET_EXPRs just should use
3912 different temporaries in their slots. */
3917 /* Virtual table reference. */
3925 {
3927 /* We compute mangled names only when free_lang_data is run.
3928 In that case we can hash precisely. */
3931 hstate.add_object
3932 (IDENTIFIER_HASH_VALUE
3934 }
3938 }
3940 /* Don't hash the type, that can lead to having nodes which
3941 compare equal according to operand_equal_p, but which
3942 have different hash codes. */
3944 {
3945 /* Make sure to include signness in the hash computation. */
3948 }
3951 {
3952 /* It's a commutative expression. We want to hash it the same
3953 however it appears. We do this by first hashing both operands
3954 and then rehashing based on the order of their independent
3955 hashes. */
3960 }
3961 else
3965 }
3967 }
3968 }
3970 bool
3973 {
3974 /* When checking and unless comparing DECL names, verify that if
3975 the outermost operand_equal_p call returns non-zero then ARG0
3976 and ARG1 have the same hash value. */
3978 {
3980 {
3982 {
3989 }
3991 }
3992 else
3996 }
3999 }
4004 /* Conveinece wrapper around operand_compare class because usually we do
4005 not need to play with the valueizer. */
4007 bool
4009 {
4011 }
4013 namespace inchash
4014 {
4016 /* Generate a hash value for an expression. This can be used iteratively
4017 by passing a previous result as the HSTATE argument.
4019 This function is intended to produce the same hash for expressions which
4020 would compare equal using operand_equal_p. */
4021 void
4023 {
4025 }
4027 }
4028 \f
4029 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
4030 with a different signedness or a narrower precision. */
4032 static bool
4034 {
4042 /* Discard any conversions that don't change the modes of ARG0 and ARG1
4043 and see if the inner values are the same. This removes any
4044 signedness comparison, which doesn't matter here. */
4052 /* Discard a single widening conversion from ARG1 and see if the inner
4053 value is the same as ARG0. */
4062 }
4063 \f
4064 /* See if ARG is an expression that is either a comparison or is performing
4065 arithmetic on comparisons. The comparisons must only be comparing
4066 two different values, which will be stored in *CVAL1 and *CVAL2; if
4067 they are nonzero it means that some operands have already been found.
4068 No variables may be used anywhere else in the expression except in the
4069 comparisons.
4071 If this is true, return 1. Otherwise, return zero. */
4073 static bool
4075 {
4079 /* We can handle some of the tcc_expression cases here. */
4088 {
4107 /* First see if we can handle the first operand, then the second. For
4108 the second operand, we know *CVAL1 can't be zero. It must be that
4109 one side of the comparison is each of the values; test for the
4110 case where this isn't true by failing if the two operands
4111 are the same. */
4120 ;
4124 ;
4125 else
4129 ;
4133 ;
4134 else
4141 }
4142 }
4143 \f
4144 /* ARG is a tree that is known to contain just arithmetic operations and
4145 comparisons. Evaluate the operations in the tree substituting NEW0 for
4146 any occurrence of OLD0 as an operand of a comparison and likewise for
4147 NEW1 and OLD1. */
4149 static tree
4152 {
4157 /* We can handle some of the tcc_expression cases here. */
4165 {
4180 {
4199 }
4200 /* Fall through - ??? */
4203 {
4207 /* We need to check both for exact equality and tree equality. The
4208 former will be true if the operand has a side-effect. In that
4209 case, we know the operand occurred exactly once. */
4222 }
4226 }
4227 }
4228 \f
4229 /* Return a tree for the case when the result of an expression is RESULT
4230 converted to TYPE and OMITTED was previously an operand of the expression
4231 but is now not needed (e.g., we folded OMITTED * 0).
4233 If OMITTED has side effects, we must evaluate it. Otherwise, just do
4234 the conversion of RESULT to TYPE. */
4236 tree
4238 {
4241 /* If the resulting operand is an empty statement, just return the omitted
4242 statement casted to void. */
4252 }
4254 /* Return a tree for the case when the result of an expression is RESULT
4255 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
4256 of the expression but are now not needed.
4258 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
4259 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
4260 evaluated before OMITTED2. Otherwise, if neither has side effects,
4261 just do the conversion of RESULT to TYPE. */
4263 tree
4266 {
4275 }
4277 \f
4278 /* Return a simplified tree node for the truth-negation of ARG. This
4279 never alters ARG itself. We assume that ARG is an operation that
4280 returns a truth value (0 or 1).
4282 FIXME: one would think we would fold the result, but it causes
4283 problems with the dominator optimizer. */
4285 static tree
4287 {
4292 /* If this is a comparison, we can simply invert it, except for
4293 floating-point non-equality comparisons, in which case we just
4294 enclose a TRUTH_NOT_EXPR around what we have. */
4297 {
4300 && flag_trapping_math
4313 }
4316 {
4335 /* Here we can invert either operand. We invert the first operand
4336 unless the second operand is a TRUTH_NOT_EXPR in which case our
4337 result is the XOR of the first operand with the inside of the
4338 negation of the second operand. */
4343 else
4366 {
4373 /* A COND_EXPR may have a throw as one operand, which
4374 then has void type. Just leave void operands
4375 as they are. */
4381 }
4393 CASE_CONVERT:
4397 /* fall through */
4419 }
4420 }
4422 /* Fold the truth-negation of ARG. This never alters ARG itself. We
4423 assume that ARG is an operation that returns a truth value (0 or 1
4424 for scalars, 0 or -1 for vectors). Return the folded expression if
4425 folding is successful. Otherwise, return NULL_TREE. */
4427 static tree
4429 {
4432 ? BIT_NOT_EXPR
4435 }
4437 /* Return a simplified tree node for the truth-negation of ARG. This
4438 never alters ARG itself. We assume that ARG is an operation that
4439 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
4441 tree
4443 {
4449 ? BIT_NOT_EXPR
4452 }
4453 \f
4454 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4455 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
4456 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
4457 is the original memory reference used to preserve the alias set of
4458 the access. */
4460 static tree
4464 {
4467 /* Attempt not to lose the access path if possible. */
4469 {
4471 machine_mode nmode;
4473 tree noffset;
4481 && !reversep
4482 && !nreversep
4484 {
4487 }
4488 }
4497 {
4504 }
4519 }
4521 /* Optimize a bit-field compare.
4523 There are two cases: First is a compare against a constant and the
4524 second is a comparison of two items where the fields are at the same
4525 bit position relative to the start of a chunk (byte, halfword, word)
4526 large enough to contain it. In these cases we can avoid the shift
4527 implicit in bitfield extractions.
4529 For constants, we emit a compare of the shifted constant with the
4530 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4531 compared. For two fields at the same position, we do the ANDs with the
4532 similar mask and compare the result of the ANDs.
4534 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4535 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4536 are the left and right operands of the comparison, respectively.
4538 If the optimization described above can be done, we return the resulting
4539 tree. Otherwise we return zero. */
4541 static tree
4544 {
4548 tree unsigned_type;
4551 scalar_int_mode nmode;
4556 tree mask;
4557 tree offset;
4559 /* Get all the information about the extractions being done. If the bit size
4560 is the same as the size of the underlying object, we aren't doing an
4561 extraction at all and so can do nothing. We also don't want to
4562 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4563 then will no longer be able to replace it. */
4578 else
4579 {
4580 /* If this is not a constant, we can only do something if bit positions,
4581 sizes, signedness and storage order are the same. */
4582 rinner
4595 }
4597 /* Honor the C++ memory model and mimic what RTL expansion does. */
4601 {
4605 }
4607 /* See if we can find a mode to refer to this field. We should be able to,
4608 but fail if we can't. */
4616 /* Set signed and unsigned types of the precision of this mode for the
4617 shifts below. */
4620 /* Compute the bit position and size for the new reference and our offset
4621 within it. If the new reference is the same size as the original, we
4622 won't optimize anything, so return zero. */
4632 /* Make the mask to be used against the extracted field. */
4639 {
4643 /* If not comparing with constant, just rework the comparison
4644 and return. */
4652 }
4654 /* Otherwise, we are handling the constant case. See if the constant is too
4655 big for the field. Warn and return a tree for 0 (false) if so. We do
4656 this not only for its own sake, but to avoid having to test for this
4657 error case below. If we didn't, we might generate wrong code.
4659 For unsigned fields, the constant shifted right by the field length should
4660 be all zero. For signed fields, the high-order bits should agree with
4661 the sign bit. */
4664 {
4666 {
4670 }
4671 }
4672 else
4673 {
4676 {
4680 }
4681 }
4686 /* Single-bit compares should always be against zero. */
4688 {
4691 }
4693 /* Make a new bitfield reference, shift the constant over the
4694 appropriate number of bits and mask it with the computed mask
4695 (in case this was a signed field). If we changed it, make a new one. */
4703 mask);
4708 }
4709 \f
4710 /* Subroutine for fold_truth_andor_1: decode a field reference.
4712 If EXP is a comparison reference, we return the innermost reference.
4714 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4715 set to the starting bit number.
4717 If the innermost field can be completely contained in a mode-sized
4718 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4720 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4721 otherwise it is not changed.
4723 *PUNSIGNEDP is set to the signedness of the field.
4725 *PREVERSEP is set to the storage order of the field.
4727 *PMASK is set to the mask used. This is either contained in a
4728 BIT_AND_EXPR or derived from the width of the field.
4730 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4732 Return 0 if this is not a component reference or is one that we can't
4733 do anything with. */
4735 static tree
4740 {
4745 tree unsigned_type;
4748 /* All the optimizations using this function assume integer fields.
4749 There are problems with FP fields since the type_for_size call
4750 below can fail for, e.g., XFmode. */
4754 /* We are interested in the bare arrangement of bits, so strip everything
4755 that doesn't affect the machine mode. However, record the type of the
4756 outermost expression if it may matter below. */
4763 {
4769 }
4780 /* Reject out-of-bound accesses (PR79731). */
4792 /* If the number of bits in the reference is the same as the bitsize of
4793 the outer type, then the outer type gives the signedness. Otherwise
4794 (in case of a small bitfield) the signedness is unchanged. */
4798 /* Compute the mask to access the bitfield. */
4806 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4814 }
4816 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4817 bit positions and MASK is SIGNED. */
4819 static bool
4821 {
4825 /* If this function returns true when the type of the mask is
4826 UNSIGNED, then there will be errors. In particular see
4827 gcc.c-torture/execute/990326-1.c. There does not appear to be
4828 any documentation paper trail as to why this is so. But the pre
4829 wide-int worked with that restriction and it has been preserved
4830 here. */
4835 }
4837 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4838 represents the sign bit of EXP's type. If EXP represents a sign
4839 or zero extension, also test VAL against the unextended type.
4840 The return value is the (sub)expression whose sign bit is VAL,
4841 or NULL_TREE otherwise. */
4843 tree
4845 {
4847 tree t;
4849 /* Tree EXP must have an integral type. */
4854 /* Tree VAL must be an integer constant. */
4863 /* Handle extension from a narrower type. */
4869 }
4871 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4872 to be evaluated unconditionally. */
4874 static bool
4876 {
4877 /* Strip any conversions that don't change the machine mode. */
4886 /* Don't regard global variables as simple. They may be
4887 allocated in ways unknown to the compiler (shared memory,
4888 #pragma weak, etc). */
4891 /* Weakrefs are not safe to be read, since they can be NULL.
4892 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4893 have DECL_WEAK flag set. */
4895 /* Loading a static variable is unduly expensive, but global
4896 registers aren't expensive. */
4898 }
4900 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4901 to be evaluated unconditionally.
4902 I addition to simple_operand_p, we assume that comparisons, conversions,
4903 and logic-not operations are simple, if their operands are simple, too. */
4905 static bool
4907 {
4926 }
4928 \f
4929 /* The following functions are subroutines to fold_range_test and allow it to
4930 try to change a logical combination of comparisons into a range test.
4932 For example, both
4933 X == 2 || X == 3 || X == 4 || X == 5
4934 and
4935 X >= 2 && X <= 5
4936 are converted to
4937 (unsigned) (X - 2) <= 3
4939 We describe each set of comparisons as being either inside or outside
4940 a range, using a variable named like IN_P, and then describe the
4941 range with a lower and upper bound. If one of the bounds is omitted,
4942 it represents either the highest or lowest value of the type.
4944 In the comments below, we represent a range by two numbers in brackets
4945 preceded by a "+" to designate being inside that range, or a "-" to
4946 designate being outside that range, so the condition can be inverted by
4947 flipping the prefix. An omitted bound is represented by a "-". For
4948 example, "- [-, 10]" means being outside the range starting at the lowest
4949 possible value and ending at 10, in other words, being greater than 10.
4950 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4951 always false.
4953 We set up things so that the missing bounds are handled in a consistent
4954 manner so neither a missing bound nor "true" and "false" need to be
4955 handled using a special case. */
4957 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4958 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4959 and UPPER1_P are nonzero if the respective argument is an upper bound
4960 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4961 must be specified for a comparison. ARG1 will be converted to ARG0's
4962 type if both are specified. */
4964 static tree
4967 {
4968 tree tem;
4972 /* If neither arg represents infinity, do the normal operation.
4973 Else, if not a comparison, return infinity. Else handle the special
4974 comparison rules. Note that most of the cases below won't occur, but
4975 are handled for consistency. */
4978 {
4983 }
4988 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4989 for neither. In real maths, we cannot assume open ended ranges are
4990 the same. But, this is computer arithmetic, where numbers are finite.
4991 We can therefore make the transformation of any unbounded range with
4992 the value Z, Z being greater than any representable number. This permits
4993 us to treat unbounded ranges as equal. */
4997 {
5018 }
5021 }
5022 \f
5023 /* Helper routine for make_range. Perform one step for it, return
5024 new expression if the loop should continue or NULL_TREE if it should
5025 stop. */
5027 tree
5031 {
5037 {
5039 /* We can only do something if the range is testing for zero. */
5048 /* We can only do something if the range is testing for zero
5049 and if the second operand is an integer constant. Note that
5050 saying something is "in" the range we make is done by
5051 complementing IN_P since it will set in the initial case of
5052 being not equal to zero; "out" is leaving it alone. */
5059 {
5080 }
5082 /* If this is an unsigned comparison, we also know that EXP is
5083 greater than or equal to zero. We base the range tests we make
5084 on that fact, so we record it here so we can parse existing
5085 range tests. We test arg0_type since often the return type
5086 of, e.g. EQ_EXPR, is boolean. */
5088 {
5092 NULL_TREE))
5097 /* If the high bound is missing, but we have a nonzero low
5098 bound, reverse the range so it goes from zero to the low bound
5099 minus 1. */
5101 {
5106 }
5107 }
5115 /* If flag_wrapv and ARG0_TYPE is signed, make sure
5116 low and high are non-NULL, then normalize will DTRT. */
5119 {
5124 }
5126 /* (-x) IN [a,b] -> x in [-b, -a] */
5138 /* ~ X -> -X - 1 */
5147 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
5148 move a constant to the other side. */
5153 /* If EXP is signed, any overflow in the computation is undefined,
5154 so we don't worry about it so long as our computations on
5155 the bounds don't overflow. For unsigned, overflow is defined
5156 and this is exactly the right thing. */
5168 normalize:
5169 /* Check for an unsigned range which has wrapped around the maximum
5170 value thus making n_high < n_low, and normalize it. */
5172 {
5178 /* If the range is of the form +/- [ x+1, x ], we won't
5179 be able to normalize it. But then, it represents the
5180 whole range or the empty set, so make it
5181 +/- [ -, - ]. */
5185 else
5187 }
5188 else
5196 CASE_CONVERT:
5214 /* If we're converting arg0 from an unsigned type, to exp,
5215 a signed type, we will be doing the comparison as unsigned.
5216 The tests above have already verified that LOW and HIGH
5217 are both positive.
5219 So we have to ensure that we will handle large unsigned
5220 values the same way that the current signed bounds treat
5221 negative values. */
5224 {
5225 tree high_positive;
5226 tree equiv_type;
5227 /* For fixed-point modes, we need to pass the saturating flag
5228 as the 2nd parameter. */
5230 equiv_type
5233 else
5234 equiv_type
5237 /* A range without an upper bound is, naturally, unbounded.
5238 Since convert would have cropped a very large value, use
5239 the max value for the destination type. */
5240 high_positive
5247 high_positive),
5250 /* If the low bound is specified, "and" the range with the
5251 range for which the original unsigned value will be
5252 positive. */
5254 {
5257 integer_zero_node),
5258 high_positive))
5262 }
5263 else
5264 {
5265 /* Otherwise, "or" the range with the range of the input
5266 that will be interpreted as negative. */
5269 integer_zero_node),
5270 high_positive))
5274 }
5275 }
5277 /* Otherwise, if we are converting arg0 from signed type, to exp,
5278 an unsigned type, we will do the comparison as signed. If
5279 high is non-NULL, we punt above if it doesn't fit in the signed
5280 type, so if we get through here, +[-, high] or +[low, high] are
5281 equivalent to +[-, n_high] or +[n_low, n_high]. Similarly,
5282 +[-, -] or -[-, -] are equivalent too. But if low is specified and
5283 high is not, the +[low, -] range is equivalent to union of
5284 +[n_low, -] and +[-, -1] ranges, so +[low, -] is equivalent to
5285 -[0, n_low-1] and similarly -[low, -] to +[0, n_low-1], except for
5286 low being 0, which should be treated as [-, -]. */
5289 && low
5291 {
5294 else
5295 {
5300 }
5301 }
5310 }
5311 }
5313 /* Given EXP, a logical expression, set the range it is testing into
5314 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
5315 actually being tested. *PLOW and *PHIGH will be made of the same
5316 type as the returned expression. If EXP is not a comparison, we
5317 will most likely not be returning a useful value and range. Set
5318 *STRICT_OVERFLOW_P to true if the return value is only valid
5319 because signed overflow is undefined; otherwise, do not change
5320 *STRICT_OVERFLOW_P. */
5322 tree
5325 {
5333 /* Start with simply saying "EXP != 0" and then look at the code of EXP
5334 and see if we can refine the range. Some of the cases below may not
5335 happen, but it doesn't seem worth worrying about this. We "continue"
5336 the outer loop when we've changed something; otherwise we "break"
5337 the switch, which will "break" the while. */
5343 {
5349 {
5357 }
5366 }
5368 /* If EXP is a constant, we can evaluate whether this is true or false. */
5370 {
5377 }
5381 }
5383 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
5384 a bitwise check i.e. when
5385 LOW == 0xXX...X00...0
5386 HIGH == 0xXX...X11...1
5387 Return corresponding mask in MASK and stem in VALUE. */
5389 static bool
5392 {
5415 }
5416 \f
5417 /* Helper routine for build_range_check and match.pd. Return the type to
5418 perform the check or NULL if it shouldn't be optimized. */
5420 tree
5422 {
5423 /* First make sure that arithmetics in this type is valid, then make sure
5424 that it wraps around. */
5429 {
5432 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5433 for the type in question, as we rely on this here. */
5443 else
5445 }
5449 }
5451 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
5452 type, TYPE, return an expression to test if EXP is in (or out of, depending
5453 on IN_P) the range. Return 0 if the test couldn't be created. */
5455 tree
5458 {
5461 /* Disable this optimization for function pointer expressions
5462 on targets that require function pointer canonicalization. */
5469 {
5475 }
5497 value);
5500 {
5502 {
5506 }
5508 }
5510 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5512 {
5516 {
5518 {
5521 etype
5523 else
5526 }
5529 }
5530 }
5532 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5533 This requires wrap-around arithmetics for the type of the expression. */
5550 }
5551 \f
5552 /* Return the predecessor of VAL in its type, handling the infinite case. */
5554 static tree
5556 {
5562 else
5565 }
5567 /* Return the successor of VAL in its type, handling the infinite case. */
5569 static tree
5571 {
5577 else
5580 }
5582 /* Given two ranges, see if we can merge them into one. Return 1 if we
5583 can, 0 if we can't. Set the output range into the specified parameters. */
5585 bool
5588 {
5592 tree tem;
5602 /* Make range 0 be the range that starts first, or ends last if they
5603 start at the same value. Swap them if it isn't. */
5606 || (lowequal
5609 {
5613 }
5615 /* If the second range is != high1 where high1 is the type maximum of
5616 the type, try first merging with < high1 range. */
5618 && high1
5625 {
5630 /* Similarly for the second range != low1 where low1 is the type minimum
5631 of the type, try first merging with > low1 range. */
5636 }
5638 /* Now flag two cases, whether the ranges are disjoint or whether the
5639 second range is totally subsumed in the first. Note that the tests
5640 below are simplified by the ones above. */
5646 /* We now have four cases, depending on whether we are including or
5647 excluding the two ranges. */
5649 {
5650 /* If they don't overlap, the result is false. If the second range
5651 is a subset it is the result. Otherwise, the range is from the start
5652 of the second to the end of the first. */
5657 else
5659 }
5662 {
5663 /* If they don't overlap, the result is the first range. If they are
5664 equal, the result is false. If the second range is a subset of the
5665 first, and the ranges begin at the same place, we go from just after
5666 the end of the second range to the end of the first. If the second
5667 range is not a subset of the first, or if it is a subset and both
5668 ranges end at the same place, the range starts at the start of the
5669 first range and ends just before the second range.
5670 Otherwise, we can't describe this as a single range. */
5676 {
5681 {
5682 /* We are in the weird situation where high0 > high1 but
5683 high1 has no successor. Punt. */
5685 }
5686 }
5688 {
5693 {
5694 /* low0 < low1 but low1 has no predecessor. Punt. */
5696 }
5697 }
5698 else
5700 }
5703 {
5704 /* If they don't overlap, the result is the second range. If the second
5705 is a subset of the first, the result is false. Otherwise,
5706 the range starts just after the first range and ends at the
5707 end of the second. */
5712 else
5713 {
5718 {
5719 /* high1 > high0 but high0 has no successor. Punt. */
5721 }
5722 }
5723 }
5725 else
5726 {
5727 /* The case where we are excluding both ranges. Here the complex case
5728 is if they don't overlap. In that case, the only time we have a
5729 range is if they are adjacent. If the second is a subset of the
5730 first, the result is the first. Otherwise, the range to exclude
5731 starts at the beginning of the first range and ends at the end of the
5732 second. */
5734 {
5739 else
5740 {
5741 /* Canonicalize - [min, x] into - [-, x]. */
5744 {
5747 GET_MODE_BITSIZE
5750 /* FALLTHROUGH */
5763 }
5765 /* Canonicalize - [x, max] into - [x, -]. */
5768 {
5771 GET_MODE_BITSIZE
5774 /* FALLTHROUGH */
5790 }
5792 /* The ranges might be also adjacent between the maximum and
5793 minimum values of the given type. For
5794 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5795 return + [x + 1, y - 1]. */
5797 {
5804 }
5805 else
5807 }
5808 }
5811 else
5813 }
5817 }
5818 \f
5820 /* Subroutine of fold, looking inside expressions of the form
5821 A op B ? A : C, where (ARG00, COMP_CODE, ARG01), ARG1 and ARG2
5822 are the three operands of the COND_EXPR. This function is
5823 being used also to optimize A op B ? C : A, by reversing the
5824 comparison first.
5826 Return a folded expression whose code is not a COND_EXPR
5827 anymore, or NULL_TREE if no folding opportunity is found. */
5829 static tree
5833 {
5835 tree tem;
5840 /* If we have A op 0 ? A : -A, consider applying the following
5841 transformations:
5843 A == 0? A : -A same as -A
5844 A != 0? A : -A same as A
5845 A >= 0? A : -A same as abs (A)
5846 A > 0? A : -A same as abs (A)
5847 A <= 0? A : -A same as -abs (A)
5848 A < 0? A : -A same as -abs (A)
5850 None of these transformations work for modes with signed
5851 zeros. If A is +/-0, the first two transformations will
5852 change the sign of the result (from +0 to -0, or vice
5853 versa). The last four will fix the sign of the result,
5854 even though the original expressions could be positive or
5855 negative, depending on the sign of A.
5857 Note that all these transformations are correct if A is
5858 NaN, since the two alternatives (A and -A) are also NaNs. */
5865 /* In the case that A is of the form X-Y, '-A' (arg2) may
5866 have already been folded to Y-X, check for that. */
5874 {
5886 /* Fall through. */
5897 /* FALLTHRU */
5904 {
5905 /* A <= 0 ? A : -A for A INT_MIN is valid, but -abs(INT_MIN)
5906 is not, invokes UB both in abs and in the negation of it.
5907 So, use ABSU_EXPR instead. */
5912 }
5913 else
5914 {
5917 }
5921 }
5923 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5924 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5925 both transformations are correct when A is NaN: A != 0
5926 is then true, and A == 0 is false. */
5930 {
5935 }
5937 /* Try some transformations of A op B ? A : B.
5939 A == B? A : B same as B
5940 A != B? A : B same as A
5941 A >= B? A : B same as max (A, B)
5942 A > B? A : B same as max (B, A)
5943 A <= B? A : B same as min (A, B)
5944 A < B? A : B same as min (B, A)
5946 As above, these transformations don't work in the presence
5947 of signed zeros. For example, if A and B are zeros of
5948 opposite sign, the first two transformations will change
5949 the sign of the result. In the last four, the original
5950 expressions give different results for (A=+0, B=-0) and
5951 (A=-0, B=+0), but the transformed expressions do not.
5953 The first two transformations are correct if either A or B
5954 is a NaN. In the first transformation, the condition will
5955 be false, and B will indeed be chosen. In the case of the
5956 second transformation, the condition A != B will be true,
5957 and A will be chosen.
5959 The conversions to max() and min() are not correct if B is
5960 a number and A is not. The conditions in the original
5961 expressions will be false, so all four give B. The min()
5962 and max() versions would give a NaN instead. */
5965 /* Avoid these transformations if the COND_EXPR may be used
5966 as an lvalue in the C++ front-end. PR c++/19199. */
5967 && (in_gimple_form
5973 {
5979 {
5988 /* In C++ a ?: expression can be an lvalue, so put the
5989 operand which will be used if they are equal first
5990 so that we can convert this back to the
5991 corresponding COND_EXPR. */
5993 {
6001 }
6008 {
6016 }
6029 }
6030 }
6033 }
6036 \f
6037 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
6038 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
6039 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
6040 false) >= 2)
6041 #endif
6043 /* EXP is some logical combination of boolean tests. See if we can
6044 merge it into some range test. Return the new tree if so. */
6046 static tree
6049 {
6063 /* If op0 is known true or false and this is a short-circuiting
6064 operation we must not merge with op1 since that makes side-effects
6065 unconditional. So special-case this. */
6072 /* If this is an OR operation, invert both sides; we will invert
6073 again at the end. */
6077 /* If both expressions are the same, if we can merge the ranges, and we
6078 can build the range test, return it or it inverted. If one of the
6079 ranges is always true or always false, consider it to be the same
6080 expression as the other. */
6088 {
6092 }
6094 /* On machines where the branch cost is expensive, if this is a
6095 short-circuited branch and the underlying object on both sides
6096 is the same, make a non-short-circuit operation. */
6099 logical_op_non_short_circuit
6106 {
6107 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
6108 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
6109 which cases we can't do this. */
6117 {
6126 {
6129 WARN_STRICT_OVERFLOW_COMPARISON);
6133 }
6134 }
6135 }
6138 }
6139 \f
6140 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
6141 bit value. Arrange things so the extra bits will be set to zero if and
6142 only if C is signed-extended to its full width. If MASK is nonzero,
6143 it is an INTEGER_CST that should be AND'ed with the extra bits. */
6145 static tree
6147 {
6150 tree temp;
6155 /* We work by getting just the sign bit into the low-order bit, then
6156 into the high-order bit, then sign-extend. We then XOR that value
6157 with C. */
6161 /* We must use a signed type in order to get an arithmetic right shift.
6162 However, we must also avoid introducing accidental overflows, so that
6163 a subsequent call to integer_zerop will work. Hence we must
6164 do the type conversion here. At this point, the constant is either
6165 zero or one, and the conversion to a signed type can never overflow.
6166 We could get an overflow if this conversion is done anywhere else. */
6175 /* If necessary, convert the type back to match the type of C. */
6180 }
6181 \f
6182 /* For an expression that has the form
6183 (A && B) || ~B
6184 or
6185 (A || B) && ~B,
6186 we can drop one of the inner expressions and simplify to
6187 A || ~B
6188 or
6189 A && ~B
6190 LOC is the location of the resulting expression. OP is the inner
6191 logical operation; the left-hand side in the examples above, while CMPOP
6192 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
6193 removing a condition that guards another, as in
6194 (A != NULL && A->...) || A == NULL
6195 which we must not transform. If RHS_ONLY is true, only eliminate the
6196 right-most operand of the inner logical operation. */
6198 static tree
6201 {
6219 {
6222 {
6225 }
6226 }
6228 {
6231 {
6234 }
6235 }
6250 }
6252 /* Find ways of folding logical expressions of LHS and RHS:
6253 Try to merge two comparisons to the same innermost item.
6254 Look for range tests like "ch >= '0' && ch <= '9'".
6255 Look for combinations of simple terms on machines with expensive branches
6256 and evaluate the RHS unconditionally.
6258 For example, if we have p->a == 2 && p->b == 4 and we can make an
6259 object large enough to span both A and B, we can do this with a comparison
6260 against the object ANDed with the a mask.
6262 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
6263 operations to do this with one comparison.
6265 We check for both normal comparisons and the BIT_AND_EXPRs made this by
6266 function and the one above.
6268 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
6269 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
6271 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
6272 two operands.
6274 We return the simplified tree or 0 if no optimization is possible. */
6276 static tree
6279 {
6280 /* If this is the "or" of two comparisons, we can do something if
6281 the comparisons are NE_EXPR. If this is the "and", we can do something
6282 if the comparisons are EQ_EXPR. I.e.,
6283 (a->b == 2 && a->c == 4) can become (a->new == NEW).
6285 WANTED_CODE is this operation code. For single bit fields, we can
6286 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
6287 comparison for one-bit fields. */
6308 /* Start by getting the comparison codes. Fail if anything is volatile.
6309 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
6310 it were surrounded with a NE_EXPR. */
6319 {
6323 }
6326 {
6330 }
6341 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
6344 {
6347 {
6352 }
6355 {
6361 }
6362 }
6367 /* If the RHS can be evaluated unconditionally and its operands are
6368 simple, it wins to evaluate the RHS unconditionally on machines
6369 with expensive branches. In this case, this isn't a comparison
6370 that can be merged. */
6377 {
6378 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
6389 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
6399 }
6401 /* See if the comparisons can be merged. Then get all the parameters for
6402 each side. */
6427 /* It must be true that the inner operation on the lhs of each
6428 comparison must be the same if we are to be able to do anything.
6429 Then see if we have constants. If not, the same must be true for
6430 the rhs's. */
6439 {
6442 }
6447 else
6450 /* If either comparison code is not correct for our logical operation,
6451 fail. However, we can convert a one-bit comparison against zero into
6452 the opposite comparison against that bit being set in the field. */
6456 {
6458 {
6459 /* Make the left operand unsigned, since we are only interested
6460 in the value of one bit. Otherwise we are doing the wrong
6461 thing below. */
6464 }
6465 else
6467 }
6469 /* This is analogous to the code for l_const above. */
6471 {
6473 {
6476 }
6477 else
6479 }
6481 /* See if we can find a mode that contains both fields being compared on
6482 the left. If we can't, fail. Otherwise, update all constants and masks
6483 to be relative to a field of that size. */
6497 {
6500 }
6510 {
6519 {
6523 }
6524 }
6526 {
6535 {
6539 }
6540 }
6542 /* If the right sides are not constant, do the same for it. Also,
6543 disallow this optimization if a size, signedness or storage order
6544 mismatch occurs between the left and right sides. */
6546 {
6550 /* Make sure the two fields on the right
6551 correspond to the left without being swapped. */
6568 {
6571 }
6582 /* Make a mask that corresponds to both fields being compared.
6583 Do this for both items being compared. If the operands are the
6584 same size and the bits being compared are in the same position
6585 then we can do this by masking both and comparing the masked
6586 results. */
6593 {
6607 }
6609 /* There is still another way we can do something: If both pairs of
6610 fields being compared are adjacent, we may be able to make a wider
6611 field containing them both.
6613 Note that we still must mask the lhs/rhs expressions. Furthermore,
6614 the mask must be shifted to account for the shift done by
6615 make_bit_field_ref. */
6624 {
6625 tree type;
6643 /* Convert to the smaller type before masking out unwanted bits. */
6646 {
6648 {
6652 }
6654 {
6658 }
6659 }
6668 }
6671 }
6673 /* Handle the case of comparisons with constants. If there is something in
6674 common between the masks, those bits of the constants must be the same.
6675 If not, the condition is always false. Test for this to avoid generating
6676 incorrect code below. */
6681 {
6683 {
6686 }
6687 else
6688 {
6691 }
6692 }
6697 /* Construct the expression we will return. First get the component
6698 reference we will make. Unless the mask is all ones the width of
6699 that field, perform the mask operation. Then compare with the
6700 merged constant. */
6711 }
6712 \f
6713 /* T is an integer expression that is being multiplied, divided, or taken a
6714 modulus (CODE says which and what kind of divide or modulus) by a
6715 constant C. See if we can eliminate that operation by folding it with
6716 other operations already in T. WIDE_TYPE, if non-null, is a type that
6717 should be used for the computation if wider than our type.
6719 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6720 (X * 2) + (Y * 4). We must, however, be assured that either the original
6721 expression would not overflow or that overflow is undefined for the type
6722 in the language in question.
6724 If we return a non-null expression, it is an equivalent form of the
6725 original computation, but need not be in the original type.
6727 We set *STRICT_OVERFLOW_P to true if the return values depends on
6728 signed overflow being undefined. Otherwise we do not change
6729 *STRICT_OVERFLOW_P. */
6731 static tree
6734 {
6735 /* To avoid exponential search depth, refuse to allow recursion past
6736 three levels. Beyond that (1) it's highly unlikely that we'll find
6737 something interesting and (2) we've probably processed it before
6738 when we built the inner expression. */
6741 tree ret;
6746 depth++;
6748 depth--;
6751 }
6753 static tree
6756 {
6768 /* Don't deal with constants of zero here; they confuse the code below. */
6778 /* Note that we need not handle conditional operations here since fold
6779 already handles those cases. So just do arithmetic here. */
6781 {
6783 /* For a constant, we can always simplify if we are a multiply
6784 or (for divide and modulus) if it is a multiple of our constant. */
6788 {
6791 /* If the multiplication overflowed, we lost information on it.
6792 See PR68142 and PR69845. */
6796 }
6802 /* If op0 is an expression ... */
6808 /* ... and has wrapping overflow, and its type is smaller
6809 than ctype, then we cannot pass through as widening. */
6813 /* ... or this is a truncation (t is narrower than op0),
6814 then we cannot pass through this narrowing. */
6817 /* ... or signedness changes for division or modulus,
6818 then we cannot pass through this conversion. */
6822 /* ... or has undefined overflow while the converted to
6823 type has not, we cannot do the operation in the inner type
6824 as that would introduce undefined overflow. */
6829 /* Pass the constant down and see if we can make a simplification. If
6830 we can, replace this expression with the inner simplification for
6831 possible later conversion to our or some other type. */
6842 /* If widening the type changes it from signed to unsigned, then we
6843 must avoid building ABS_EXPR itself as unsigned. */
6845 {
6849 {
6852 }
6854 }
6855 /* If the constant is negative, we cannot simplify this. */
6858 /* FALLTHROUGH */
6860 /* For division and modulus, type can't be unsigned, as e.g.
6861 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6862 For signed types, even with wrapping overflow, this is fine. */
6871 /* If widening the type changes the signedness, then we can't perform
6872 this optimization as that changes the result. */
6876 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6882 {
6889 }
6893 /* If the second operand is constant, this is a multiplication
6894 or floor division, by a power of two, so we can treat it that
6895 way unless the multiplier or divisor overflows. Signed
6896 left-shift overflow is implementation-defined rather than
6897 undefined in C90, so do not convert signed left shift into
6898 multiplication. */
6901 /* const_binop may not detect overflow correctly,
6902 so check for it explicitly here. */
6911 ctype,
6913 t1),
6918 /* See if we can eliminate the operation on both sides. If we can, we
6919 can return a new PLUS or MINUS. If we can't, the only remaining
6920 cases where we can do anything are if the second operand is a
6921 constant. */
6928 /* If not multiplication, we can only do this if both operands
6929 are divisible by c. */
6932 {
6937 }
6939 /* If this was a subtraction, negate OP1 and set it to be an addition.
6940 This simplifies the logic below. */
6942 {
6944 /* If OP1 was not easily negatable, the constant may be OP0. */
6946 {
6949 }
6950 }
6955 /* If either OP1 or C are negative, this optimization is not safe for
6956 some of the division and remainder types while for others we need
6957 to change the code. */
6959 {
6967 }
6969 /* If it's a multiply or a division/modulus operation of a multiple
6970 of our constant, do the operation and verify it doesn't overflow. */
6974 {
6977 /* We allow the constant to overflow with wrapping semantics. */
6981 }
6982 else
6985 /* If we have an unsigned type, we cannot widen the operation since it
6986 will change the result if the original computation overflowed. */
6990 /* The last case is if we are a multiply. In that case, we can
6991 apply the distributive law to commute the multiply and addition
6992 if the multiplication of the constants doesn't overflow
6993 and overflow is defined. With undefined overflow
6994 op0 * c might overflow, while (op0 + orig_op1) * c doesn't.
6995 But fold_plusminus_mult_expr would factor back any power-of-two
6996 value so do not distribute in the first place in this case. */
7004 op1);
7009 /* We have a special case here if we are doing something like
7010 (C * 8) % 4 since we know that's zero. */
7013 /* If the multiplication can overflow we cannot optimize this. */
7018 {
7021 }
7023 /* ... fall through ... */
7027 /* If we can extract our operation from the LHS, do so and return a
7028 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
7029 do something only if the second operand is a constant. */
7045 /* If these are the same operation types, we can associate them
7046 assuming no overflow. */
7048 {
7063 }
7065 /* If these operations "cancel" each other, we have the main
7066 optimizations of this pass, which occur when either constant is a
7067 multiple of the other, in which case we replace this with either an
7068 operation or CODE or TCODE.
7070 If we have an unsigned type, we cannot do this since it will change
7071 the result if the original computation overflowed. */
7078 {
7081 {
7088 }
7091 {
7098 }
7099 }
7104 }
7107 }
7108 \f
7109 /* Return a node which has the indicated constant VALUE (either 0 or
7110 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
7111 and is of the indicated TYPE. */
7113 tree
7115 {
7124 else
7126 }
7129 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
7130 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
7131 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
7132 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
7133 COND is the first argument to CODE; otherwise (as in the example
7134 given here), it is the second argument. TYPE is the type of the
7135 original expression. Return NULL_TREE if no simplification is
7136 possible. */
7138 static tree
7143 {
7151 /* Do not move possibly trapping operations into the conditional as this
7152 pessimizes code and causes gimplification issues when applied late. */
7160 {
7164 /* If this operand throws an expression, then it does not make
7165 sense to try to perform a logical or arithmetic operation
7166 involving it. */
7171 }
7174 {
7179 }
7180 else
7181 /* Detect the case of mixing vector and scalar types - bail out. */
7187 /* This transformation is only worthwhile if we don't have to wrap ARG
7188 in a SAVE_EXPR and the operation can be simplified without recursing
7189 on at least one of the branches once its pushed inside the COND_EXPR. */
7198 {
7202 else
7204 }
7206 {
7210 else
7212 }
7214 /* Check that we have simplified at least one of the branches. */
7219 }
7221 \f
7222 /* Subroutine of fold() that checks for the addition of ARG +/- 0.0.
7224 If !NEGATE, return true if ZERO_ARG is +/-0.0 and, for all ARG of
7225 type TYPE, ARG + ZERO_ARG is the same as ARG. If NEGATE, return true
7226 if ARG - ZERO_ARG is the same as X.
7228 If ARG is NULL, check for any value of type TYPE.
7230 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
7231 and finite. The problematic cases are when X is zero, and its mode
7232 has signed zeros. In the case of rounding towards -infinity,
7233 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
7234 modes, X + 0 is not the same as X because -0 + 0 is 0. */
7236 bool
7239 {
7243 /* Don't allow the fold with -fsignaling-nans. */
7247 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
7251 /* There is no case that is safe for all rounding modes. */
7255 /* In a vector or complex, we would need to check the sign of all zeros. */
7261 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
7265 /* The mode has signed zeros, and we have to honor their sign.
7266 In this situation, there are only two cases we can return true for.
7267 (i) X - 0 is the same as X with default rounding.
7268 (ii) X + 0 is X when X can't possibly be -0.0. */
7270 }
7272 /* Subroutine of match.pd that optimizes comparisons of a division by
7273 a nonzero integer constant against an integer constant, i.e.
7274 X/C1 op C2.
7276 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7277 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
7279 enum tree_code
7282 {
7287 /* We have to do this the hard way to detect unsigned overflow.
7288 prod = int_const_binop (MULT_EXPR, c1, c2); */
7294 {
7298 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
7301 }
7303 {
7306 {
7325 }
7326 }
7327 else
7328 {
7329 /* A negative divisor reverses the relational operators. */
7334 {
7353 }
7354 }
7367 }
7370 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7371 equality/inequality test, then return a simplified form of the test
7372 using a sign testing. Otherwise return NULL. TYPE is the desired
7373 result type. */
7375 static tree
7378 tree result_type)
7379 {
7380 /* If this is testing a single bit, we can optimize the test. */
7384 {
7385 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7386 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7390 /* This is only a win if casting to a signed type is cheap,
7391 i.e. when arg00's type is not a partial mode. */
7393 {
7396 result_type,
7399 }
7400 }
7403 }
7405 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7406 equality/inequality test, then return a simplified form of
7407 the test using shifts and logical operations. Otherwise return
7408 NULL. TYPE is the desired result type. */
7410 tree
7413 {
7414 /* If this is testing a single bit, we can optimize the test. */
7418 {
7427 /* First, see if we can fold the single bit test into a sign-bit
7428 test. */
7430 result_type);
7434 /* Otherwise we have (A & C) != 0 where C is a single bit,
7435 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7436 Similarly for (A & C) == 0. */
7438 /* If INNER is a right shift of a constant and it plus BITNUM does
7439 not overflow, adjust BITNUM and INNER. */
7445 {
7448 }
7450 /* If we are going to be able to omit the AND below, we must do our
7451 operations as unsigned. If we must use the AND, we have a choice.
7452 Normally unsigned is faster, but for some machines signed is. */
7470 /* Put the AND last so it can combine with more things. */
7473 /* Make sure to return the proper type. */
7477 }
7479 }
7481 /* Test whether it is preferable to swap two operands, ARG0 and
7482 ARG1, for example because ARG0 is an integer constant and ARG1
7483 isn't. */
7485 bool
7487 {
7501 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7502 for commutative and comparison operators. Ensuring a canonical
7503 form allows the optimizers to find additional redundancies without
7504 having to explicitly check for both orderings. */
7510 /* Put SSA_NAMEs last. */
7516 /* Put variables last. */
7523 }
7526 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7527 means A >= Y && A != MAX, but in this case we know that
7528 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7530 static tree
7532 {
7539 else
7548 {
7551 }
7553 {
7556 }
7557 else
7564 {
7565 /* Convert the pointer types into integer before taking the difference. */
7569 }
7570 else
7577 }
7579 /* Fold a sum or difference of at least one multiplication.
7580 Returns the folded tree or NULL if no simplification could be made. */
7582 static tree
7585 {
7589 /* (A * C) +- (B * C) -> (A+-B) * C.
7590 (A * C) +- A -> A * (C+-1).
7591 We are most concerned about the case where C is a constant,
7592 but other combinations show up during loop reduction. Since
7593 it is not difficult, try all four possibilities. */
7596 {
7599 }
7601 {
7604 }
7605 else
7606 {
7607 /* We cannot generate constant 1 for fract. */
7612 }
7614 {
7617 }
7619 {
7621 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7622 the purpose of this canonicalization. */
7626 {
7629 }
7630 else
7632 }
7633 else
7634 {
7635 /* We cannot generate constant 1 for fract. */
7640 }
7643 /* Prefer factoring a common non-constant. */
7653 /* No identical multiplicands; see if we can find a common
7654 power-of-two factor in non-power-of-two multiplies. This
7655 can help in multi-dimensional array access. */
7657 {
7660 HOST_WIDE_INT tmp;
7662 tree maybe_same;
7664 /* Move min of absolute values to int11. */
7666 {
7671 }
7672 else
7679 /* The remainder should not be a constant, otherwise we
7680 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7681 increased the number of multiplications necessary. */
7683 {
7691 }
7692 }
7699 /* We are neither factoring zero nor minus one. */
7707 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7708 same may be minus one and thus the multiplication may overflow. Perform
7709 the sum operation in an unsigned type. */
7714 /* If the sum evaluated to a constant that is not -INF the multiplication
7715 cannot overflow. */
7722 /* Do not resort to unsigned multiplication because
7723 we lose the no-overflow property of the expression. */
7725 }
7727 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7728 specified by EXPR into the buffer PTR of length LEN bytes.
7729 Return the number of bytes placed in the buffer, or zero
7730 upon failure. */
7732 static int
7734 {
7746 /* Dry run. */
7752 {
7754 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7755 number of bytes. */
7759 {
7766 else
7768 }
7769 else
7773 }
7775 }
7778 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7779 specified by EXPR into the buffer PTR of length LEN bytes.
7780 Return the number of bytes placed in the buffer, or zero
7781 upon failure. */
7783 static int
7785 {
7789 FIXED_VALUE_TYPE value;
7804 }
7807 /* Subroutine of native_encode_expr. Encode the REAL_CST
7808 specified by EXPR into the buffer PTR of length LEN bytes.
7809 Return the number of bytes placed in the buffer, or zero
7810 upon failure. */
7812 static int
7814 {
7820 /* There are always 32 bits in each long, no matter the size of
7821 the hosts long. We handle floating point representations with
7822 up to 192 bits. */
7831 /* Dry run. */
7840 {
7845 {
7852 else
7854 }
7855 else
7856 {
7859 {
7860 /* Reverse bytes within each long, or within the entire float
7861 if it's smaller than a long (for HFmode). */
7864 }
7865 }
7870 }
7872 }
7874 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7875 specified by EXPR into the buffer PTR of length LEN bytes.
7876 Return the number of bytes placed in the buffer, or zero
7877 upon failure. */
7879 static int
7881 {
7883 tree part;
7897 }
7899 /* Like native_encode_vector, but only encode the first COUNT elements.
7900 The other arguments are as for native_encode_vector. */
7902 static int
7905 {
7909 {
7910 /* This is the only case in which elements can be smaller than a byte.
7911 Element 0 is always in the lsb of the containing byte. */
7920 /* Zero the buffer and then set bits later where necessary. */
7929 {
7935 {
7938 }
7939 }
7941 }
7946 {
7948 {
7951 }
7962 }
7964 }
7966 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7967 specified by EXPR into the buffer PTR of length LEN bytes.
7968 Return the number of bytes placed in the buffer, or zero
7969 upon failure. */
7971 static int
7973 {
7978 }
7981 /* Subroutine of native_encode_expr. Encode the STRING_CST
7982 specified by EXPR into the buffer PTR of length LEN bytes.
7983 Return the number of bytes placed in the buffer, or zero
7984 upon failure. */
7986 static int
7988 {
7991 /* Wide-char strings are encoded in target byte-order so native
7992 encoding them is trivial. */
8007 else
8008 {
8011 {
8014 }
8016 }
8018 }
8021 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST, REAL_CST,
8022 FIXED_CST, COMPLEX_CST, STRING_CST, or VECTOR_CST specified by EXPR into
8023 the buffer PTR of size LEN bytes. If PTR is NULL, don't actually store
8024 anything, just do a dry run. Fail either if OFF is -1 and LEN isn't
8025 sufficient to encode the entire EXPR, or if OFF is out of bounds.
8026 Otherwise, start at byte offset OFF and encode at most LEN bytes.
8027 Return the number of bytes placed in the buffer, or zero upon failure. */
8029 int
8031 {
8032 /* We don't support starting at negative offset and -1 is special. */
8037 {
8058 }
8059 }
8061 /* Try to find a type whose byte size is smaller or equal to LEN bytes larger
8062 or equal to FIELDSIZE bytes, with underlying mode precision/size multiple
8063 of BITS_PER_UNIT. As native_{interpret,encode}_int works in term of
8064 machine modes, we can't just use build_nonstandard_integer_type. */
8066 tree
8068 {
8069 machine_mode mode;
8071 {
8078 {
8082 }
8083 }
8089 {
8097 }
8100 }
8102 /* Similar to native_encode_expr, but also handle CONSTRUCTORs, VCEs,
8103 NON_LVALUE_EXPRs and nops. If MASK is non-NULL (then PTR has
8104 to be non-NULL and OFF zero), then in addition to filling the
8105 bytes pointed by PTR with the value also clear any bits pointed
8106 by MASK that are known to be initialized, keep them as is for
8107 e.g. uninitialized padding bits or uninitialized fields. */
8109 int
8112 {
8115 /* We don't support starting at negative offset and -1 is special. */
8123 {
8127 mask);
8142 {
8143 tree min_index;
8161 {
8166 {
8169 }
8174 else
8178 {
8182 offset_int wpos
8190 offset_int wcount
8197 }
8199 {
8202 offset_int wpos
8210 }
8213 {
8215 {
8226 }
8228 {
8232 }
8233 }
8237 do
8238 {
8243 {
8245 {
8248 fieldsize);
8251 }
8253 ptr
8256 fieldsize,
8259 mask
8263 else
8264 {
8267 }
8268 }
8271 {
8272 /* Partial overlap. */
8278 {
8282 fieldsize);
8283 }
8284 else
8285 {
8289 }
8292 }
8294 }
8296 }
8298 }
8301 {
8311 {
8317 {
8320 }
8323 {
8332 }
8336 else
8340 {
8341 tree fld;
8343 {
8356 }
8358 {
8362 }
8365 {
8366 cnt--;
8372 }
8373 }
8378 {
8391 {
8396 }
8397 }
8398 else
8399 {
8404 }
8409 {
8416 else
8422 }
8431 {
8432 /* FIXME: Handle PDP endian. */
8443 {
8446 }
8447 else
8448 {
8456 else
8457 {
8460 }
8461 }
8471 else
8484 /* If the bitfield does not start at byte boundary, handle
8485 the partial byte at the start. */
8488 {
8490 {
8495 {
8498 else
8500 }
8501 }
8502 else
8503 {
8508 {
8511 else
8515 }
8516 }
8517 }
8518 /* If the bitfield does not end at byte boundary, handle
8519 the partial byte at the end. */
8523 {
8525 {
8532 }
8533 else
8534 {
8541 }
8542 }
8546 {
8551 }
8552 else
8553 {
8554 /* Partial overlap. */
8558 {
8561 }
8565 }
8567 }
8572 {
8575 {
8578 {
8582 }
8585 }
8588 fldsize,
8598 }
8599 else
8600 {
8601 /* Partial overlap. */
8607 {
8611 fieldsize);
8612 }
8613 else
8614 {
8618 }
8621 }
8622 }
8624 }
8626 }
8627 }
8630 /* Subroutine of native_interpret_expr. Interpret the contents of
8631 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8632 If the buffer cannot be interpreted, return NULL_TREE. */
8634 static tree
8636 {
8646 }
8649 /* Subroutine of native_interpret_expr. Interpret the contents of
8650 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
8651 If the buffer cannot be interpreted, return NULL_TREE. */
8653 static tree
8655 {
8658 double_int result;
8659 FIXED_VALUE_TYPE fixed_value;
8669 }
8672 /* Subroutine of native_interpret_expr. Interpret the contents of
8673 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8674 If the buffer cannot be interpreted, return NULL_TREE. */
8676 tree
8678 {
8682 /* There are always 32 bits in each long, no matter the size of
8683 the hosts long. We handle floating point representations with
8684 up to 192 bits. */
8685 REAL_VALUE_TYPE r;
8695 {
8696 /* Both OFFSET and BYTE index within a long;
8697 bitpos indexes the whole float. */
8700 {
8707 else
8709 }
8710 else
8711 {
8714 {
8715 /* Reverse bytes within each long, or within the entire float
8716 if it's smaller than a long (for HFmode). */
8719 }
8720 }
8724 }
8728 }
8731 /* Subroutine of native_interpret_expr. Interpret the contents of
8732 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8733 If the buffer cannot be interpreted, return NULL_TREE. */
8735 static tree
8737 {
8752 }
8754 /* Read a vector of type TYPE from the target memory image given by BYTES,
8755 which contains LEN bytes. The vector is known to be encodable using
8756 NPATTERNS interleaved patterns with NELTS_PER_PATTERN elements each.
8758 Return the vector on success, otherwise return null. */
8760 static tree
8764 {
8768 {
8769 /* This is the only case in which elements can be smaller than a byte.
8770 Element 0 is always in the lsb of the containing byte. */
8777 {
8784 }
8786 }
8794 {
8800 }
8802 }
8804 /* Subroutine of native_interpret_expr. Interpret the contents of
8805 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8806 If the buffer cannot be interpreted, return NULL_TREE. */
8808 static tree
8810 {
8811 tree etype;
8822 }
8825 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8826 the buffer PTR of length LEN as a constant of type TYPE. For
8827 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8828 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8829 return NULL_TREE. */
8831 tree
8833 {
8835 {
8846 {
8847 /* For floating point values in composite modes, punt if this
8848 folding doesn't preserve bit representation. As the mode doesn't
8849 have fixed precision while GCC pretends it does, there could be
8850 valid values that GCC can't really represent accurately.
8851 See PR95450. Even for other modes, e.g. x86 XFmode can have some
8852 bit combinationations which GCC doesn't preserve. */
8860 }
8874 }
8875 }
8877 /* Returns true if we can interpret the contents of a native encoding
8878 as TYPE. */
8880 bool
8882 {
8884 {
8898 }
8899 }
8901 /* Attempt to interpret aggregate of TYPE from bytes encoded in target
8902 byte order at PTR + OFF with LEN bytes. Does not handle unions. */
8904 tree
8907 {
8910 {
8917 {
8921 }
8926 {
8931 {
8936 }
8940 eltsz);
8944 }
8946 }
8950 {
8958 {
8961 {
8962 poly_int64 bitoffset;
8967 else
8977 }
8978 else
8979 {
8997 HOST_WIDE_INT rpos;
9000 else
9001 {
9004 }
9013 }
9014 }
9017 {
9027 }
9031 {
9036 }
9043 {
9047 /* FIXME: Figure out how to handle PDP endian bitfields. */
9053 else
9057 }
9059 }
9061 }
9063 /* Routines for manipulation of native_encode_expr encoded data if the encoded
9064 or extracted constant positions and/or sizes aren't byte aligned. */
9066 /* Shift left the bytes in PTR of SZ elements by AMNT bits, carrying over the
9067 bits between adjacent elements. AMNT should be within
9068 [0, BITS_PER_UNIT).
9069 Example, AMNT = 2:
9070 00011111|11100000 << 2 = 01111111|10000000
9071 PTR[1] | PTR[0] PTR[1] | PTR[0]. */
9073 void
9076 {
9085 {
9091 {
9094 }
9095 }
9096 }
9098 /* Like shift_bytes_in_array_left but for big-endian.
9099 Shift right the bytes in PTR of SZ elements by AMNT bits, carrying over the
9100 bits between adjacent elements. AMNT should be within
9101 [0, BITS_PER_UNIT).
9102 Example, AMNT = 2:
9103 00011111|11100000 >> 2 = 00000111|11111000
9104 PTR[0] | PTR[1] PTR[0] | PTR[1]. */
9106 void
9109 {
9117 {
9124 }
9125 }
9127 /* Try to view-convert VECTOR_CST EXPR to VECTOR_TYPE TYPE by operating
9128 directly on the VECTOR_CST encoding, in a way that works for variable-
9129 length vectors. Return the resulting VECTOR_CST on success or null
9130 on failure. */
9132 static tree
9134 {
9146 /* We can only preserve the semantics of a stepped pattern if the new
9147 vector element is an integer of the same size. */
9152 /* The number of bits needed to encode one element from every pattern
9153 of the original vector. */
9154 unsigned int expr_sequence_bits
9157 /* The number of bits needed to encode one element from every pattern
9158 of the result. */
9159 unsigned int type_sequence_bits
9162 /* Don't try to read more bytes than are available, which can happen
9163 for constant-sized vectors if TYPE has larger elements than EXPR_TYPE.
9164 The general VIEW_CONVERT handling can cope with that case, so there's
9165 no point complicating things here. */
9168 BITS_PER_UNIT);
9173 /* Get enough bytes of EXPR to form the new encoding. */
9181 /* Reencode the bytes as TYPE. */
9185 }
9187 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
9188 TYPE at compile-time. If we're unable to perform the conversion
9189 return NULL_TREE. */
9191 static tree
9193 {
9194 /* We support up to 512-bit values (for V8DFmode). */
9198 /* Check that the host and target are sane. */
9211 }
9213 /* Build an expression for the address of T. Folds away INDIRECT_REF
9214 to avoid confusing the gimplify process. */
9216 tree
9218 {
9219 /* The size of the object is not relevant when talking about its address. */
9224 {
9229 }
9232 {
9237 }
9244 {
9249 }
9250 else
9254 }
9256 /* Build an expression for the address of T. */
9258 tree
9260 {
9264 }
9266 /* Fold a unary expression of code CODE and type TYPE with operand
9267 OP0. Return the folded expression if folding is successful.
9268 Otherwise, return NULL_TREE. */
9270 tree
9272 {
9273 tree tem;
9274 tree arg0;
9282 {
9285 {
9286 /* Don't use STRIP_NOPS, because signedness of argument type
9287 matters. */
9289 }
9290 else
9291 {
9292 /* Strip any conversions that don't change the mode. This
9293 is safe for every expression, except for a comparison
9294 expression because its signedness is derived from its
9295 operands.
9297 Note that this is done as an internal manipulation within
9298 the constant folder, in order to find the simplest
9299 representation of the arguments so that their form can be
9300 studied. In any cases, the appropriate type conversions
9301 should be put back in the tree that will get out of the
9302 constant folder. */
9304 }
9307 {
9310 {
9314 }
9315 }
9316 }
9323 {
9330 {
9344 /* If this was a conversion, and all we did was to move into
9345 inside the COND_EXPR, bring it back out. But leave it if
9346 it is a conversion from integer to integer and the
9347 result precision is no wider than a word since such a
9348 conversion is cheap and may be optimized away by combine,
9349 while it couldn't if it were outside the COND_EXPR. Then return
9350 so we don't get into an infinite recursion loop taking the
9351 conversion out and then back in. */
9363 && (INTEGRAL_TYPE_P
9376 }
9377 }
9380 {
9386 CASE_CONVERT:
9390 {
9391 /* If we have (type) (a CMP b) and type is an integral type, return
9392 new expression involving the new type. Canonicalize
9393 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
9394 non-integral type.
9395 Do not fold the result as that would not simplify further, also
9396 folding again results in recursions. */
9406 }
9408 /* Handle (T *)&A.B.C for A being of type T and B and C
9409 living at offset zero. This occurs frequently in
9410 C++ upcasting and then accessing the base. */
9414 {
9416 tree offset;
9417 machine_mode mode;
9419 tree base
9423 /* If the reference was to a (constant) zero offset, we can use
9424 the address of the base if it has the same base type
9425 as the result type and the pointer type is unqualified. */
9433 }
9437 /* Detect assigning a bitfield. */
9439 && DECL_BIT_FIELD
9441 {
9442 /* Don't leave an assignment inside a conversion
9443 unless assigning a bitfield. */
9445 /* First do the assignment, then return converted constant. */
9450 }
9452 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
9453 constants (if x has signed type, the sign bit cannot be set
9454 in c). This folds extension into the BIT_AND_EXPR.
9455 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
9456 very likely don't have maximal range for their precision and this
9457 transformation effectively doesn't preserve non-maximal ranges. */
9461 {
9472 <= HOST_BITS_PER_WIDE_INT
9474 {
9478 cst &= HOST_WIDE_INT_M1U
9482 && !flag_syntax_only
9485 {
9489 }
9490 }
9492 {
9497 }
9498 }
9500 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
9501 cast (T1)X will fold away. We assume that this happens when X itself
9502 is a cast. */
9506 {
9510 /* If -fsanitize=alignment, avoid this optimization in GENERIC
9511 when the pointed type needs higher alignment than
9512 the p+ first operand's pointed type. */
9519 /* Similarly, avoid this optimization in GENERIC for -fsanitize=null
9520 when type is a reference type and arg00's type is not,
9521 because arg00 could be validly nullptr and if arg01 doesn't return,
9522 we don't want false positive binding of reference to nullptr. */
9524 && !in_gimple_form
9531 }
9533 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
9534 of the same precision, and X is an integer type not narrower than
9535 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
9541 {
9547 }
9549 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
9550 type of X and Y (integer types only). */
9555 {
9556 /* Be careful not to introduce new overflows. */
9557 tree mult_type;
9560 else
9564 {
9571 }
9572 }
9578 {
9585 }
9596 /* Convert fabs((double)float) into (double)fabsf(float). */
9599 {
9605 targ0));
9606 }
9610 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
9629 /* Note that the operand of this must be an int
9630 and its values must be 0 or 1.
9631 ("true" is a fixed value perhaps depending on the language,
9632 but we don't handle values other than 1 correctly yet.) */
9639 /* Fold *&X to X if X is an lvalue. */
9641 {
9648 }
9654 }
9657 /* If the operation was a conversion do _not_ mark a resulting constant
9658 with TREE_OVERFLOW if the original constant was not. These conversions
9659 have implementation defined behavior and retaining the TREE_OVERFLOW
9660 flag here would confuse later passes such as VRP. */
9661 tree
9664 {
9673 }
9675 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
9676 operands OP0 and OP1. LOC is the location of the resulting expression.
9677 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
9678 Return the folded expression if folding is successful. Otherwise,
9679 return NULL_TREE. */
9680 static tree
9683 {
9684 tree tem;
9686 /* We only do these simplifications if we are optimizing. */
9690 /* Check for things like (A || B) && (A || C). We can convert this
9691 to A || (B && C). Note that either operator can be any of the four
9692 truth and/or operations and the transformation will still be
9693 valid. Also note that we only care about order for the
9694 ANDIF and ORIF operators. If B contains side effects, this
9695 might change the truth-value of A. */
9702 {
9722 /* This case if tricky because we must either have commutative
9723 operators or else A10 must not have side-effects. */
9729 a01);
9730 }
9732 /* See if we can build a range comparison. */
9738 {
9742 }
9746 {
9750 }
9752 /* Check for the possibility of merging component references. If our
9753 lhs is another similar operation, try to merge its rhs with our
9754 rhs. Then try to merge our lhs and rhs. */
9765 logical_op_non_short_circuit
9773 {
9780 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
9781 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
9782 We don't want to pack more than two leafs to a non-IF AND/OR
9783 expression.
9784 If tree-code of left-hand operand isn't an AND/OR-IF code and not
9785 equal to IF-CODE, then we don't want to add right-hand operand.
9786 If the inner right-hand side of left-hand operand has
9787 side-effects, or isn't simple, then we can't add to it,
9788 as otherwise we might destroy if-sequence. */
9791 /* Needed for sequence points to handle trappings, and
9792 side-effects. */
9794 {
9796 arg1);
9798 tem);
9799 }
9800 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
9801 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
9804 /* Needed for sequence points to handle trappings, and
9805 side-effects. */
9807 {
9812 }
9813 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
9814 into (A OR B).
9815 For sequence point consistancy, we need to check for trapping,
9816 and side-effects. */
9820 }
9823 }
9825 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9826 by changing CODE to reduce the magnitude of constants involved in
9827 ARG0 of the comparison.
9828 Returns a canonicalized comparison tree if a simplification was
9829 possible, otherwise returns NULL_TREE.
9830 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9831 valid if signed overflow is undefined. */
9833 static tree
9837 {
9842 /* Match A +- CST code arg1. We can change this only if overflow
9843 is undefined. */
9846 /* In principle pointers also have undefined overflow behavior,
9847 but that causes problems elsewhere. */
9854 /* Identify the constant in arg0 and its sign. */
9858 /* Overflowed constants and zero will cause problems. */
9863 /* See if we can reduce the magnitude of the constant in
9864 arg0 by changing the comparison code. */
9865 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9869 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9873 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9877 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9881 else
9885 /* Now build the constant reduced in magnitude. But not if that
9886 would produce one outside of its types range. */
9902 }
9904 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9905 overflow further. Try to decrease the magnitude of constants involved
9906 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9907 and put sole constants at the second argument position.
9908 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9910 static tree
9913 {
9914 tree t;
9919 /* Try canonicalization by simplifying arg0. */
9924 {
9928 }
9930 /* Try canonicalization by simplifying arg1 using the swapped
9931 comparison. */
9939 }
9941 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9942 space. This is used to avoid issuing overflow warnings for
9943 expressions like &p->x which cannot wrap. */
9945 static bool
9947 {
9954 poly_wide_int wi_offset;
9960 else
9965 precision);
9980 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9981 array. */
9990 }
9992 /* Return a positive integer when the symbol DECL is known to have
9993 a nonzero address, zero when it's known not to (e.g., it's a weak
9994 symbol), and a negative integer when the symbol is not yet in the
9995 symbol table and so whether or not its address is zero is unknown.
9996 For function local objects always return positive integer. */
9997 static int
9999 {
10000 /* Normally, don't do anything for variables and functions before symtab is
10001 built; it is quite possible that DECL will be declared weak later.
10002 But if folding_initializer, we need a constant answer now, so create
10003 the symtab entry and prevent later weak declaration. */
10006 = (folding_initializer
10011 /* Function local objects are never NULL. */
10019 }
10021 /* Subroutine of fold_binary. This routine performs all of the
10022 transformations that are common to the equality/inequality
10023 operators (EQ_EXPR and NE_EXPR) and the ordering operators
10024 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
10025 fold_binary should call fold_binary. Fold a comparison with
10026 tree code CODE and type TYPE with operands OP0 and OP1. Return
10027 the folded comparison or NULL_TREE. */
10029 static tree
10032 {
10042 /* For comparisons of pointers we can decompose it to a compile time
10043 comparison of the base objects and the offsets into the object.
10044 This requires at least one operand being an ADDR_EXPR or a
10045 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
10051 {
10054 machine_mode mode;
10058 /* Get base and offset for the access. Strip ADDR_EXPR for
10059 get_inner_reference, but put it back by stripping INDIRECT_REF
10060 off the base object if possible. indirect_baseN will be true
10061 if baseN is not an address but refers to the object itself. */
10064 {
10065 base0
10071 else
10073 }
10075 {
10079 {
10080 base0
10086 else
10088 }
10091 else
10095 {
10102 }
10103 }
10107 {
10108 base1
10114 else
10116 }
10118 {
10122 {
10123 base1
10129 else
10131 }
10134 else
10138 {
10145 }
10146 }
10148 /* If we have equivalent bases we might be able to simplify. */
10152 {
10153 /* We can fold this expression to a constant if the non-constant
10154 offset parts are equal. */
10158 && (equality_code
10159 || (indirect_base0
10162 {
10168 "occur when comparing P +- C1 with "
10170 WARN_STRICT_OVERFLOW_CONDITIONAL);
10173 {
10211 }
10212 }
10213 /* We can simplify the comparison to a comparison of the variable
10214 offset parts if the constant offset parts are equal.
10215 Be careful to use signed sizetype here because otherwise we
10216 mess with array offsets in the wrong way. This is possible
10217 because pointer arithmetic is restricted to retain within an
10218 object and overflow on pointer differences is undefined as of
10219 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
10221 && (equality_code
10222 || (indirect_base0
10225 {
10226 /* By converting to signed sizetype we cover middle-end pointer
10227 arithmetic which operates on unsigned pointer types of size
10228 type size and ARRAY_REF offsets which are properly sign or
10229 zero extended from their type in case it is narrower than
10230 sizetype. */
10233 else
10237 else
10244 "occur when comparing P +- C1 with "
10246 WARN_STRICT_OVERFLOW_COMPARISON);
10249 }
10250 }
10251 /* For equal offsets we can simplify to a comparison of the
10252 base addresses. */
10254 && (indirect_base0
10256 && (indirect_base1
10261 {
10267 }
10268 /* Comparison between an ordinary (non-weak) symbol and a null
10269 pointer can be eliminated since such symbols must have a non
10270 null address. In C, relational expressions between pointers
10271 to objects and null pointers are undefined. The results
10272 below follow the C++ rules with the additional property that
10273 every object pointer compares greater than a null pointer.
10274 */
10277 /* Avoid folding references to struct members at offset 0 to
10278 prevent tests like '&ptr->firstmember == 0' from getting
10279 eliminated. When ptr is null, although the -> expression
10280 is strictly speaking invalid, GCC retains it as a matter
10281 of QoI. See PR c/44555. */
10284 && indirect_base0
10285 /* The caller guarantees that when one of the arguments is
10286 constant (i.e., null in this case) it is second. */
10288 {
10290 {
10301 }
10302 }
10303 }
10305 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
10306 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
10307 the resulting offset is smaller in absolute value than the
10308 original one and has the same sign. */
10317 {
10322 tree cst;
10324 "occur when combining constants around "
10327 /* Put the constant on the side where it doesn't overflow and is
10328 of lower absolute value and of same sign than before. */
10335 {
10338 variable1,
10342 }
10350 {
10356 variable2);
10357 }
10358 }
10364 /* If we are comparing an expression that just has comparisons
10365 of two integer values, arithmetic expressions of those comparisons,
10366 and constants, we can simplify it. There are only three cases
10367 to check: the two values can either be equal, the first can be
10368 greater, or the second can be greater. Fold the expression for
10369 those three values. Since each value must be 0 or 1, we have
10370 eight possibilities, each of which corresponds to the constant 0
10371 or 1 or one of the six possible comparisons.
10373 This handles common cases like (a > b) == 0 but also handles
10374 expressions like ((x > y) - (y > x)) > 0, which supposedly
10375 occur in macroized code. */
10378 {
10382 /* Don't handle degenerate cases here; they should already
10383 have been handled anyway. */
10392 {
10396 /* We can't just pass T to eval_subst in case cval1 or cval2
10397 was the same as ARG1. */
10399 tree high_result
10403 arg1);
10404 tree equal_result
10408 arg1);
10409 tree low_result
10413 arg1);
10415 /* All three of these results should be 0 or 1. Confirm they are.
10416 Then use those values to select the proper code to use. */
10421 {
10422 /* Make a 3-bit mask with the high-order bit being the
10423 value for `>', the next for '=', and the low for '<'. */
10427 {
10429 /* Always false. */
10450 /* Always true. */
10452 }
10455 }
10456 }
10457 }
10460 }
10463 /* Subroutine of fold_binary. Optimize complex multiplications of the
10464 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
10465 argument EXPR represents the expression "z" of type TYPE. */
10467 static tree
10469 {
10474 {
10477 }
10479 {
10482 }
10483 else
10484 {
10488 }
10497 }
10500 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
10501 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
10502 true if successful. */
10504 static bool
10506 {
10511 {
10514 }
10516 {
10522 else
10524 }
10525 else
10531 }
10533 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
10534 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
10535 NULL_TREE otherwise. */
10537 tree
10539 {
10560 {
10561 HOST_WIDE_INT index;
10567 }
10570 {
10576 }
10577 else
10579 }
10581 /* Try to fold a pointer difference of type TYPE two address expressions of
10582 array references AREF0 and AREF1 using location LOC. Return a
10583 simplified expression for the difference or NULL_TREE. */
10585 static tree
10589 {
10594 /* If the bases are array references as well, recurse. If the bases
10595 are pointer indirections compute the difference of the pointers.
10596 If the bases are equal, we are set. */
10599 && (base_offset
10601 use_pointer_diff)))
10604 && (base_offset
10605 = use_pointer_diff
10615 {
10621 base_offset,
10624 }
10626 }
10628 /* If the real or vector real constant CST of type TYPE has an exact
10629 inverse, return it, else return NULL. */
10631 tree
10633 {
10634 REAL_VALUE_TYPE r;
10635 tree unit_type;
10636 machine_mode mode;
10639 {
10649 {
10653 tree_vector_builder elts;
10658 {
10663 }
10666 }
10670 }
10671 }
10673 /* Mask out the tz least significant bits of X of type TYPE where
10674 tz is the number of trailing zeroes in Y. */
10675 static wide_int
10677 {
10682 }
10684 /* Return true when T is an address and is known to be nonzero.
10685 For floating point we further ensure that T is not denormal.
10686 Similar logic is present in nonzero_address in rtlanal.h.
10688 If the return value is based on the assumption that signed overflow
10689 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
10690 change *STRICT_OVERFLOW_P. */
10692 static bool
10694 {
10698 /* Doing something useful for floating point would need more work. */
10704 {
10707 strict_overflow_p);
10713 strict_overflow_p);
10721 }
10724 {
10727 strict_overflow_p);
10735 strict_overflow_p);
10750 strict_overflow_p);
10754 strict_overflow_p);
10757 {
10769 }
10773 }
10775 }
10777 /* Return true when T is an address and is known to be nonzero.
10778 Handle warnings about undefined signed overflow. */
10780 bool
10782 {
10789 "determining that expression is always "
10791 WARN_STRICT_OVERFLOW_MISC);
10793 }
10795 /* Return true if T is known not to be equal to an integer W. */
10797 bool
10799 {
10800 int_range_max vr;
10802 {
10812 else
10818 /* If T has some known zero bits and W has any of those bits set,
10819 then T is known not to be equal to W. */
10827 }
10828 }
10830 /* Fold a binary expression of code CODE and type TYPE with operands
10831 OP0 and OP1. LOC is the location of the resulting expression.
10832 Return the folded expression if folding is successful. Otherwise,
10833 return NULL_TREE. */
10835 tree
10838 {
10853 /* Strip any conversions that don't change the mode. This is
10854 safe for every expression, except for a comparison expression
10855 because its signedness is derived from its operands. So, in
10856 the latter case, only strip conversions that don't change the
10857 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10858 preserved.
10860 Note that this is done as an internal manipulation within the
10861 constant folder, in order to find the simplest representation
10862 of the arguments so that their form can be studied. In any
10863 cases, the appropriate type conversions should be put back in
10864 the tree that will get out of the constant folder. */
10867 {
10870 }
10871 else
10872 {
10875 }
10877 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10878 constant but we can't do arithmetic on them. */
10880 {
10883 {
10887 }
10888 }
10890 /* If this is a commutative operation, and ARG0 is a constant, move it
10891 to ARG1 to reduce the number of tests below. */
10896 /* Likewise if this is a comparison, and ARG0 is a constant, move it
10897 to ARG1 to reduce the number of tests below. */
10906 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10908 First check for cases where an arithmetic operation is applied to a
10909 compound, conditional, or comparison operation. Push the arithmetic
10910 operation inside the compound or conditional to see if any folding
10911 can then be done. Convert comparison to conditional for this purpose.
10912 The also optimizes non-constant cases that used to be done in
10913 expand_expr.
10915 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10916 one of the operands is a comparison and the other is a comparison, a
10917 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10918 code below would make the expression more complex. Change it to a
10919 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10920 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10933 {
10937 boolean_type_node,
10945 }
10949 {
10951 {
10956 tem);
10957 }
10959 {
10964 tem);
10965 }
10970 {
10976 }
10981 {
10987 }
10988 }
10991 {
10993 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10996 {
11002 }
11004 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
11007 {
11008 tree base;
11009 poly_int64 coffset;
11018 }
11023 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
11029 arg1),
11031 arg0)));
11037 {
11038 /* X + (X / CST) * -CST is X % CST. */
11043 {
11052 cst0));
11053 }
11054 }
11056 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
11057 one. Make sure the type is not saturating and has the signedness of
11058 the stripped operands, as fold_plusminus_mult_expr will re-associate.
11059 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
11066 {
11070 }
11073 {
11074 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
11075 (plus (plus (mult) (mult)) (foo)) so that we can
11076 take advantage of the factoring cases below. */
11085 {
11091 else
11104 parg0),
11106 marg)),
11110 return
11116 parg1)));
11117 }
11118 }
11119 else
11120 {
11121 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
11122 to __complex__ ( x, y ). This is not the same for SNaNs or
11123 if signed zeros are involved. */
11127 {
11134 {
11138 {
11144 }
11146 {
11152 }
11153 }
11154 }
11156 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
11157 We associate floats only if the user has specified
11158 -fassociative-math. */
11162 {
11167 {
11168 tree tree0;
11171 }
11172 }
11173 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
11174 We associate floats only if the user has specified
11175 -fassociative-math. */
11179 {
11184 {
11185 tree tree0;
11188 }
11189 }
11190 }
11192 bit_rotate:
11193 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
11194 is a rotate of A by C1 bits. */
11195 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
11196 is a rotate of A by B bits.
11197 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
11198 though in this case CODE must be | and not + or ^, otherwise
11199 it doesn't return A when B is 0. */
11200 {
11202 tree rtype;
11211 /* Only create rotates in complete modes. Other cases are not
11212 expanded properly. */
11215 {
11228 {
11233 }
11238 {
11241 code0 == LSHIFT_EXPR
11244 }
11246 {
11256 {
11260 orig_tree01);
11262 }
11263 }
11267 {
11278 {
11282 orig_tree01);
11284 }
11285 }
11286 }
11287 }
11289 associate:
11290 /* In most languages, can't associate operations on floats through
11291 parentheses. Rather than remember where the parentheses were, we
11292 don't associate floats at all, unless the user has specified
11293 -fassociative-math.
11294 And, we need to make sure type is not saturating. */
11298 {
11304 /* Split both trees into variables, constants, and literals. Then
11305 associate each group together, the constants with literals,
11306 then the result with variables. This increases the chances of
11307 literals being recombined later and of generating relocatable
11308 expressions for the sum of a constant and literal. */
11316 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
11320 /* With undefined overflow prefer doing association in a type
11321 which wraps on overflow, if that is one of the operand types. */
11324 {
11332 }
11334 /* With undefined overflow we can only associate constants with one
11335 variable, and constants whose association doesn't overflow. */
11338 {
11340 {
11341 /* ??? If split_tree would handle NEGATE_EXPR we could
11342 simply reject these cases and the allowed cases would
11343 be the var0/minus_var1 ones. */
11349 {
11352 }
11359 {
11362 }
11368 /* The only case we can still associate with two variables
11369 is if they cancel out. */
11373 }
11379 }
11381 /* Only do something if we found more than two objects. Otherwise,
11382 nothing has changed and we risk infinite recursion. */
11390 {
11402 {
11406 }
11408 {
11412 }
11414 /* Preserve the MINUS_EXPR if the negative part of the literal is
11415 greater than the positive part. Otherwise, the multiplicative
11416 folding code (i.e extract_muldiv) may be fooled in case
11417 unsigned constants are subtracted, like in the following
11418 example: ((X*2 + 4) - 8U)/2. */
11420 {
11424 /* But avoid ending up with only negated parts. */
11426 {
11430 }
11431 else
11432 {
11436 }
11437 }
11439 /* Don't introduce overflows through reassociation. */
11444 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
11451 /* Eliminate minus_con0. */
11453 {
11460 else
11463 }
11465 /* Eliminate minus_var0. */
11467 {
11471 else
11474 }
11476 return
11479 }
11480 }
11486 /* Fold &a[i] - &a[j] to i-j. */
11491 {
11495 code
11499 }
11501 /* Further transformations are not for pointers. */
11505 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
11508 /* If arg0 is e.g. unsigned int and type is int, then this could
11509 introduce UB, because if A is INT_MIN at runtime, the original
11510 expression can be well defined while the latter is not.
11511 See PR83269. */
11520 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
11521 __complex__ ( x, -y ). This is not the same for SNaNs or if
11522 signed zeros are involved. */
11526 {
11533 {
11537 {
11539 arg1r ? arg1r
11544 }
11546 {
11550 arg1i ? arg1i
11553 }
11554 }
11555 }
11557 /* A - B -> A + (-B) if B is easily negatable. */
11561 /* Avoid this transformation if B is a positive REAL_CST. */
11569 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
11570 one. Make sure the type is not saturating and has the signedness of
11571 the stripped operands, as fold_plusminus_mult_expr will re-associate.
11572 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
11579 {
11583 }
11589 {
11590 /* Transform x * -C into -x * C if x is easily negatable. */
11605 {
11608 "occur when simplifying "
11610 WARN_STRICT_OVERFLOW_MISC);
11612 }
11614 /* Optimize z * conj(z) for integer complex numbers. */
11621 }
11622 else
11623 {
11624 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11625 This is not the same for NaNs or if signed zeros are
11626 involved. */
11632 {
11635 return
11641 return
11646 }
11648 /* Optimize z * conj(z) for floating point complex numbers.
11649 Guarded by flag_unsafe_math_optimizations as non-finite
11650 imaginary components don't produce scalar results. */
11659 }
11663 /* Canonicalize (X & C1) | C2. */
11667 {
11672 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11680 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11682 {
11685 }
11687 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11688 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11689 mode which allows further optimizations. */
11694 {
11699 {
11702 }
11703 }
11706 {
11711 }
11712 }
11714 /* See if this can be simplified into a rotate first. If that
11715 is unsuccessful continue in the association code. */
11719 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11727 /* See if this can be simplified into a rotate first. If that
11728 is unsuccessful continue in the association code. */
11732 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11737 {
11738 tree tem2;
11745 }
11746 /* Fold ~X & 1 as (X & 1) == 0. */
11750 {
11751 tree tem2;
11758 }
11759 /* Fold !X & 1 as X == 0. */
11762 {
11766 }
11768 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11769 multiple of 1 << CST. */
11771 {
11778 }
11780 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11781 bits from CST2. */
11785 {
11787 wide_int masked
11794 {
11795 /* Avoid the transform if arg1 is a mask of some
11796 mode which allows further optimizations. */
11803 }
11804 }
11806 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11809 {
11814 return
11816 }
11821 /* Don't touch a floating-point divide by zero unless the mode
11822 of the constant can represent infinity. */
11828 /* (-A) / (-B) -> A / B */
11840 /* Fall through */
11843 /* Simplify A / (B << N) where A and B are positive and B is
11844 a power of 2, to A >> (N + log2(B)). */
11849 {
11852 {
11860 WARN_STRICT_OVERFLOW_MISC);
11866 }
11867 }
11869 /* Fall through */
11877 /* Convert -A / -B to A / B when the type is signed and overflow is
11878 undefined. */
11882 {
11885 "when distributing negation across "
11887 WARN_STRICT_OVERFLOW_MISC);
11892 }
11896 {
11899 "when distributing negation across "
11901 WARN_STRICT_OVERFLOW_MISC);
11906 }
11908 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11909 operation, EXACT_DIV_EXPR.
11911 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11912 At one time others generated faster code, it's not clear if they do
11913 after the last round to changes to the DIV code in expmed.cc. */
11924 {
11928 WARN_STRICT_OVERFLOW_MISC);
11930 }
11942 {
11946 WARN_STRICT_OVERFLOW_MISC);
11948 }
11956 /* Since negative shift count is not well-defined,
11957 don't try to compute it in the compiler. */
11963 /* If we have a rotate of a bit operation with the rotate count and
11964 the second operand of the bit operation both constant,
11965 permute the two operations. */
11971 {
11979 }
11981 /* Two consecutive rotates adding up to the some integer
11982 multiple of the precision of the type can be ignored. */
11998 /* Note that the operands of this must be ints
11999 and their values must be 0 or 1.
12000 ("true" is a fixed value perhaps depending on the language.) */
12001 /* If first arg is constant zero, return it. */
12004 /* FALLTHRU */
12006 /* If either arg is constant true, drop it. */
12010 /* Preserve sequence points. */
12013 /* If second arg is constant zero, result is zero, but first arg
12014 must be evaluated. */
12017 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12018 case will be handled here. */
12022 /* !X && X is always false. */
12026 /* X && !X is always false. */
12031 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12032 means A >= Y && A != MAX, but in this case we know that
12033 A < X <= MAX. */
12037 {
12049 }
12058 /* Note that the operands of this must be ints
12059 and their values must be 0 or true.
12060 ("true" is a fixed value perhaps depending on the language.) */
12061 /* If first arg is constant true, return it. */
12064 /* FALLTHRU */
12066 /* If either arg is constant zero, drop it. */
12070 /* Preserve sequence points. */
12073 /* If second arg is constant true, result is true, but we must
12074 evaluate first arg. */
12077 /* Likewise for first arg, but note this only occurs here for
12078 TRUTH_OR_EXPR. */
12082 /* !X || X is always true. */
12086 /* X || !X is always true. */
12091 /* (X && !Y) || (!X && Y) is X ^ Y */
12094 {
12111 }
12120 /* If the second arg is constant zero, drop it. */
12123 /* If the second arg is constant true, this is a logical inversion. */
12125 {
12128 }
12129 /* Identical arguments cancel to zero. */
12133 /* !X ^ X is always true. */
12138 /* X ^ !X is always true. */
12154 /* bool_var != 1 becomes !bool_var. */
12161 /* bool_var == 0 becomes !bool_var. */
12168 /* !exp != 0 becomes !exp */
12173 /* If this is an EQ or NE comparison with zero and ARG0 is
12174 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12175 two operations, but the latter can be done in one less insn
12176 on machines that have only two-operand insns or on which a
12177 constant cannot be the first operand. */
12180 {
12185 {
12193 }
12196 {
12204 }
12205 }
12207 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12208 C1 is a valid shift constant, and C2 is a power of two, i.e.
12209 a single bit. */
12213 {
12218 {
12223 /* Check for a valid shift count. */
12225 {
12229 /* If (C2 << C1) doesn't overflow, then
12230 ((X >> C1) & C2) != 0 can be rewritten as
12231 (X & (C2 << C1)) != 0. */
12233 {
12240 }
12241 /* Otherwise, for signed (arithmetic) shifts,
12242 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12243 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12249 /* Otherwise, of unsigned (logical) shifts,
12250 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12251 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12252 else
12256 arg000);
12257 }
12258 }
12259 }
12261 /* If this is a comparison of a field, we may be able to simplify it. */
12264 /* Handle the constant case even without -O
12265 to make sure the warnings are given. */
12267 {
12271 }
12273 /* Optimize comparisons of strlen vs zero to a compare of the
12274 first character of the string vs zero. To wit,
12275 strlen(ptr) == 0 => *ptr == 0
12276 strlen(ptr) != 0 => *ptr != 0
12277 Other cases should reduce to one of these two (or a constant)
12278 due to the return value of strlen being unsigned. */
12280 {
12288 {
12289 tree ptrtype
12291 TYPE_QUAL_CONST));
12297 }
12298 }
12300 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12301 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12305 {
12310 {
12312 {
12315 }
12318 }
12319 }
12321 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12322 (X & C) == 0 when C is a single bit. */
12327 {
12334 arg1));
12335 }
12337 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12338 constant C is a power of two, i.e. a single bit. */
12345 {
12349 }
12351 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12352 when is C is a power of two, i.e. a single bit. */
12359 {
12365 }
12369 {
12372 }
12376 {
12383 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12384 operand_equal_p guarantees no side-effects so we don't need
12385 to use omit_one_operand on Z. */
12389 arg10));
12393 arg11));
12397 arg10));
12401 arg11));
12403 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12406 {
12412 }
12413 }
12415 /* Attempt to simplify equality/inequality comparisons of complex
12416 values. Only lower the comparison if the result is known or
12417 can be simplified to a single scalar comparison. */
12422 {
12427 {
12430 }
12431 else
12432 {
12435 }
12438 {
12441 }
12442 else
12443 {
12446 }
12450 {
12452 {
12457 }
12458 else
12459 {
12464 }
12465 }
12469 {
12471 {
12476 }
12477 else
12478 {
12483 }
12484 }
12485 }
12497 /* Transform comparisons of the form X +- C CMP X. */
12502 {
12507 /* (X - c) > X becomes false. */
12513 /* Likewise (X + c) < X becomes false. */
12519 /* Convert (X - c) <= X to true. */
12526 /* Convert (X + c) >= X to true. */
12532 }
12534 /* If we are comparing an ABS_EXPR with a constant, we can
12535 convert all the cases into explicit comparisons, but they may
12536 well not be faster than doing the ABS and one comparison.
12537 But ABS (X) <= C is a range comparison, which becomes a subtraction
12538 and a comparison, and is probably faster. */
12552 /* Convert ABS_EXPR<x> >= 0 to true. */
12559 {
12562 "when simplifying comparison of "
12564 WARN_STRICT_OVERFLOW_CONDITIONAL);
12567 arg0);
12568 }
12570 /* Convert ABS_EXPR<x> < 0 to false. */
12575 {
12578 "when simplifying comparison of "
12580 WARN_STRICT_OVERFLOW_CONDITIONAL);
12583 arg0);
12584 }
12586 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12587 and similarly for >= into !=. */
12597 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
12598 otherwise Y might be >= # of bits in X's type and thus e.g.
12599 (unsigned char) (1 << Y) for Y 15 might be 0.
12600 If the cast is widening, then 1 << Y should have unsigned type,
12601 otherwise if Y is number of bits in the signed shift type minus 1,
12602 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
12603 31 might be 0xffffffff80000000. */
12616 {
12622 }
12634 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12635 {
12647 }
12652 /* When pedantic, a compound expression can be neither an lvalue
12653 nor an integer constant expression. */
12656 /* Don't let (0, 0) be null pointer constant. */
12662 /* An ASSERT_EXPR should never be passed to fold_binary. */
12668 }
12670 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
12671 ((A & N) + B) & M -> (A + B) & M
12672 Similarly if (N & M) == 0,
12673 ((A | N) + B) & M -> (A + B) & M
12674 and for - instead of + (or unary - instead of +)
12675 and/or ^ instead of |.
12676 If B is constant and (B & M) == 0, fold into A & M.
12678 This function is a helper for match.pd patterns. Return non-NULL
12679 type in which the simplified operation should be performed only
12680 if any optimization is possible.
12682 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
12683 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
12684 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
12685 +/-. */
12686 tree
12691 {
12706 wide_int cst0;
12708 /* Now we know that arg0 is (C + D) or (C - D) or -C and
12709 arg1 (M) is == (1LL << cst) - 1.
12710 Store C into PMOP[0] and D into PMOP[1]. */
12717 {
12724 {
12727 }
12730 /* If C or D is of the form (A & N) where
12731 (N & M) == M, or of the form (A | N) or
12732 (A ^ N) where (N & M) == 0, replace it with A. */
12738 /* If C or D is a N where (N & M) == 0, it can be
12739 omitted (replaced with 0). */
12744 /* Similarly, with C - N where (-N & M) == 0. */
12752 }
12754 /* Only build anything new if we optimized one or both arguments above. */
12760 else
12762 }
12764 /* Used by contains_label_[p1]. */
12766 struct contains_label_data
12767 {
12770 };
12772 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
12773 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
12774 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
12776 static tree
12778 {
12781 {
12792 {
12800 }
12809 }
12810 }
12812 /* Return whether the sub-tree ST contains a label which is accessible from
12813 outside the sub-tree. */
12815 static bool
12817 {
12821 }
12823 /* Fold a ternary expression of code CODE and type TYPE with operands
12824 OP0, OP1, and OP2. Return the folded expression if folding is
12825 successful. Otherwise, return NULL_TREE. */
12827 tree
12830 {
12831 tree tem;
12838 /* If this is a commutative operation, and OP0 is a constant, move it
12839 to OP1 to reduce the number of tests below. */
12848 /* Strip any conversions that don't change the mode. This is safe
12849 for every expression, except for a comparison expression because
12850 its signedness is derived from its operands. So, in the latter
12851 case, only strip conversions that don't change the signedness.
12853 Note that this is done as an internal manipulation within the
12854 constant folder, in order to find the simplest representation of
12855 the arguments so that their form can be studied. In any cases,
12856 the appropriate type conversions should be put back in the tree
12857 that will get out of the constant folder. */
12859 {
12862 }
12865 {
12868 }
12871 {
12874 }
12877 {
12881 {
12887 }
12892 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12893 so all simple results must be passed through pedantic_non_lvalue. */
12895 {
12898 /* Only optimize constant conditions when the selected branch
12899 has the same type as the COND_EXPR. This avoids optimizing
12900 away "c ? x : throw", where the throw has a void type.
12901 Avoid throwing away that operand which contains label. */
12908 }
12910 {
12917 {
12920 {
12928 }
12933 }
12934 }
12936 /* If we have A op B ? A : C, we may be able to convert this to a
12937 simpler expression, depending on the operation and the values
12938 of B and C. Signed zeros prevent all of these transformations,
12939 for reasons given above each one.
12941 Also try swapping the arguments and inverting the conditional. */
12945 {
12952 }
12957 {
12964 arg00,
12965 arg01,
12969 }
12971 /* If the second operand is simpler than the third, swap them
12972 since that produces better jump optimization results. */
12975 {
12977 /* See if this can be inverted. If it can't, possibly because
12978 it was a floating-point inequality comparison, don't do
12979 anything. */
12983 }
12985 /* Convert A ? 1 : 0 to simply A. */
12990 /* If we try to convert OP0 to our type, the
12991 call to fold will try to move the conversion inside
12992 a COND, which will recurse. In that case, the COND_EXPR
12993 is probably the best choice, so leave it alone. */
12997 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12998 over COND_EXPR in cases such as floating point comparisons. */
13007 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13012 {
13013 /* sign_bit_p looks through both zero and sign extensions,
13014 but for this optimization only sign extensions are
13015 usable. */
13018 {
13021 {
13024 }
13026 }
13027 /* sign_bit_p only checks ARG1 bits within A's precision.
13028 If <sign bit of A> has wider type than A, bits outside
13029 of A's precision in <sign bit of A> need to be checked.
13030 If they are all 0, this optimization needs to be done
13031 in unsigned A's type, if they are all 1 in signed A's type,
13032 otherwise this can't be done. */
13038 {
13040 tree tem_type;
13053 {
13056 }
13058 {
13061 }
13062 else
13064 }
13067 return
13073 arg1)));
13074 }
13076 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13077 already handled above. */
13082 {
13092 op1);
13093 }
13095 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13096 is probably obsolete because the first operand should be a
13097 truth value (that's why we have the two cases above), but let's
13098 leave it in until we can confirm this for all front-ends. */
13106 /* operand_equal_p compares just value, not precision, so e.g.
13107 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
13108 second operand 32-bit -128, which is not a power of two (or vice
13109 versa. */
13113 /* Disable the transformations below for vectors, since
13114 fold_binary_op_with_conditional_arg may undo them immediately,
13115 yielding an infinite loop. */
13119 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13128 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13133 {
13135 /* Only perform transformation if ARG0 is easily inverted. */
13139 ? BIT_IOR_EXPR
13142 op1);
13143 }
13145 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13150 {
13152 /* Only perform transformation if ARG0 is easily inverted. */
13158 op2);
13159 }
13161 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13173 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13174 of fold_ternary on them. */
13184 {
13186 unsigned HOST_WIDE_INT width
13197 {
13202 {
13204 {
13209 }
13215 }
13216 }
13217 }
13219 /* On constants we can use native encode/interpret to constant
13220 fold (nearly) all BIT_FIELD_REFs. */
13226 {
13229 /* Limit us to a reasonable amount of work. To relax the
13230 other limitations we need bit-shifting of the buffer
13231 and rounding up the size. */
13235 {
13237 unsigned HOST_WIDE_INT len
13242 {
13247 }
13248 }
13249 }
13254 /* Perform constant folding of BIT_INSERT_EXPR. */
13258 {
13259 /* Build a vector of integers from the tree mask. */
13260 vec_perm_builder builder;
13264 /* Create a vec_perm_indices for the integer vector. */
13269 }
13273 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
13276 {
13282 wide_int tem2
13286 }
13291 {
13293 unsigned HOST_WIDE_INT elsize
13296 {
13302 {
13308 }
13309 }
13310 }
13316 }
13318 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
13319 of an array (or vector). *CTOR_IDX if non-NULL is updated with the
13320 constructor element index of the value returned. If the element is
13321 not found NULL_TREE is returned and *CTOR_IDX is updated to
13322 the index of the element after the ACCESS_INDEX position (which
13323 may be outside of the CTOR array). */
13325 tree
13328 {
13334 {
13337 {
13338 /* Static constructors for variably sized objects makes no sense. */
13341 /* ??? When it is obvious that the range is signed, treat it so. */
13346 {
13348 low_bound
13350 SIGNED);
13351 }
13352 else
13353 {
13356 }
13357 }
13358 }
13362 index_sgn);
13374 {
13375 /* Array constructor might explicitly set index, or specify a range,
13376 or leave index NULL meaning that it is next index after previous
13377 one. */
13379 {
13381 max_index = index
13383 else
13384 {
13387 index_sgn);
13388 max_index
13390 index_sgn);
13392 }
13393 }
13395 {
13401 }
13402 else
13405 /* Do we have match? */
13407 {
13409 {
13413 }
13414 }
13416 /* We're past the element we search for. Note during parsing
13417 the elements might not be sorted.
13418 ??? We should use a binary search and a flag on the
13419 CONSTRUCTOR as to whether elements are sorted in declaration
13420 order. */
13422 }
13426 }
13428 /* Perform constant folding and related simplification of EXPR.
13429 The related simplifications include x*1 => x, x*0 => 0, etc.,
13430 and application of the associative law.
13431 NOP_EXPR conversions may be removed freely (as long as we
13432 are careful not to change the type of the overall expression).
13433 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13434 but we can constant-fold them if they have constant operands. */
13436 #ifdef ENABLE_FOLD_CHECKING
13437 # define fold(x) fold_1 (x)
13439 static
13440 #endif
13441 tree
13443 {
13447 tree tem;
13450 /* Return right away if a constant. */
13454 /* CALL_EXPR-like objects with variable numbers of operands are
13455 treated specially. */
13457 {
13459 {
13462 }
13464 }
13467 {
13472 {
13490 }
13491 }
13494 {
13496 {
13503 {
13508 }
13511 }
13513 /* Return a VECTOR_CST if possible. */
13515 {
13521 tree val;
13527 }
13535 }
13537 #ifdef ENABLE_FOLD_CHECKING
13538 #undef fold
13545 /* When --enable-checking=fold, compute a digest of expr before
13546 and after actual fold call to see if fold did not accidentally
13547 change original expr. */
13549 tree
13551 {
13552 tree ret;
13572 }
13574 void
13576 {
13587 }
13589 static void
13591 {
13593 }
13595 static void
13598 {
13604 recursive_label:
13614 {
13615 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
13623 }
13631 {
13632 /* Allow these fields to be modified. */
13633 tree tmp;
13644 {
13647 }
13648 }
13650 {
13651 /* Allow the no-warning bit to be set. Perhaps we shouldn't allow
13652 that and change builtins.cc etc. instead - see PR89543. */
13658 }
13669 {
13672 {
13688 }
13692 {
13705 }
13722 {
13728 }
13731 {
13733 {
13736 }
13738 }
13749 {
13752 }
13762 }
13763 }
13765 /* Helper function for outputting the checksum of a tree T. When
13766 debugging with gdb, you can "define mynext" to be "next" followed
13767 by "call debug_fold_checksum (op0)", then just trace down till the
13768 outputs differ. */
13770 DEBUG_FUNCTION void
13772 {
13787 }
13789 #endif
13791 /* Fold a unary tree expression with code CODE of type TYPE with an
13792 operand OP0. LOC is the location of the resulting expression.
13793 Return a folded expression if successful. Otherwise, return a tree
13794 expression with code CODE of type TYPE with an operand OP0. */
13796 tree
13799 {
13800 tree tem;
13801 #ifdef ENABLE_FOLD_CHECKING
13810 #endif
13816 #ifdef ENABLE_FOLD_CHECKING
13823 #endif
13825 }
13827 /* Fold a binary tree expression with code CODE of type TYPE with
13828 operands OP0 and OP1. LOC is the location of the resulting
13829 expression. Return a folded expression if successful. Otherwise,
13830 return a tree expression with code CODE of type TYPE with operands
13831 OP0 and OP1. */
13833 tree
13836 MEM_STAT_DECL)
13837 {
13838 tree tem;
13839 #ifdef ENABLE_FOLD_CHECKING
13856 #endif
13862 #ifdef ENABLE_FOLD_CHECKING
13877 #endif
13879 }
13881 /* Fold a ternary tree expression with code CODE of type TYPE with
13882 operands OP0, OP1, and OP2. Return a folded expression if
13883 successful. Otherwise, return a tree expression with code CODE of
13884 type TYPE with operands OP0, OP1, and OP2. */
13886 tree
13889 {
13890 tree tem;
13891 #ifdef ENABLE_FOLD_CHECKING
13915 #endif
13922 #ifdef ENABLE_FOLD_CHECKING
13945 #endif
13947 }
13949 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
13950 arguments in ARGARRAY, and a null static chain.
13951 Return a folded expression if successful. Otherwise, return a CALL_EXPR
13952 of type TYPE from the given operands as constructed by build_call_array. */
13954 tree
13957 {
13958 tree tem;
13959 #ifdef ENABLE_FOLD_CHECKING
13978 #endif
13984 #ifdef ENABLE_FOLD_CHECKING
14000 #endif
14002 }
14004 /* Perform constant folding and related simplification of initializer
14005 expression EXPR. These behave identically to "fold_buildN" but ignore
14006 potential run-time traps and exceptions that fold must preserve. */
14008 #define START_FOLD_INIT \
14009 int saved_signaling_nans = flag_signaling_nans;\
14010 int saved_trapping_math = flag_trapping_math;\
14011 int saved_rounding_math = flag_rounding_math;\
14012 int saved_trapv = flag_trapv;\
14013 int saved_folding_initializer = folding_initializer;\
14014 flag_signaling_nans = 0;\
14015 flag_trapping_math = 0;\
14016 flag_rounding_math = 0;\
14017 flag_trapv = 0;\
14018 folding_initializer = 1;
14020 #define END_FOLD_INIT \
14021 flag_signaling_nans = saved_signaling_nans;\
14022 flag_trapping_math = saved_trapping_math;\
14023 flag_rounding_math = saved_rounding_math;\
14024 flag_trapv = saved_trapv;\
14025 folding_initializer = saved_folding_initializer;
14027 tree
14029 {
14030 tree result;
14031 START_FOLD_INIT;
14035 END_FOLD_INIT;
14037 }
14039 tree
14042 {
14043 tree result;
14044 START_FOLD_INIT;
14048 END_FOLD_INIT;
14050 }
14052 tree
14055 {
14056 tree result;
14057 START_FOLD_INIT;
14061 END_FOLD_INIT;
14063 }
14065 tree
14068 {
14069 tree result;
14070 START_FOLD_INIT;
14074 END_FOLD_INIT;
14076 }
14078 tree
14081 {
14082 tree result;
14083 START_FOLD_INIT;
14087 END_FOLD_INIT;
14089 }
14091 #undef START_FOLD_INIT
14092 #undef END_FOLD_INIT
14094 /* Determine if first argument is a multiple of second argument. Return 0 if
14095 it is not, or we cannot easily determined it to be.
14097 An example of the sort of thing we care about (at this point; this routine
14098 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14099 fold cases do now) is discovering that
14101 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14103 is a multiple of
14105 SAVE_EXPR (J * 8)
14107 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14109 This code also handles discovering that
14111 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14113 is a multiple of 8 so we don't have to worry about dealing with a
14114 possible remainder.
14116 Note that we *look* inside a SAVE_EXPR only to determine how it was
14117 calculated; it is not safe for fold to do much of anything else with the
14118 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14119 at run time. For example, the latter example above *cannot* be implemented
14120 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14121 evaluation time of the original SAVE_EXPR is not necessarily the same at
14122 the time the new expression is evaluated. The only optimization of this
14123 sort that would be valid is changing
14125 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14127 divided by 8 to
14129 SAVE_EXPR (I) * SAVE_EXPR (J)
14131 (where the same SAVE_EXPR (J) is used in the original and the
14132 transformed version).
14134 NOWRAP specifies whether all outer operations in TYPE should
14135 be considered not wrapping. Any type conversion within TOP acts
14136 as a barrier and we will fall back to NOWRAP being false.
14137 NOWRAP is mostly used to treat expressions in TYPE_SIZE and friends
14138 as not wrapping even though they are generally using unsigned arithmetic. */
14140 int
14142 {
14153 {
14155 /* Bitwise and provides a power of two multiple. If the mask is
14156 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14163 /* If the multiplication can wrap we cannot recurse further unless
14164 the bottom is a power of two which is where wrapping does not
14165 matter. */
14171 {
14177 {
14180 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
14182 {
14186 {
14189 }
14190 }
14192 }
14193 }
14198 /* Handle X << CST as X * (1 << CST) and only process the constant. */
14200 {
14203 {
14204 wide_int mul_op
14208 nowrap);
14209 }
14210 }
14215 /* If the addition or subtraction can wrap we cannot recurse further
14216 unless bottom is a power of two which is where wrapping does not
14217 matter. */
14223 /* Handle cases like op0 + 0xfffffffd as op0 - 3 if the expression has
14224 unsigned type. For example, (X / 3) + 0xfffffffd is multiple of 3,
14225 but 0xfffffffd is not. */
14228 && nowrap
14233 /* It is impossible to prove if op0 +- op1 is multiple of bottom
14234 precisely, so be conservative here checking if both op0 and op1
14235 are multiple of bottom. Note we check the second operand first
14236 since it's usually simpler. */
14240 CASE_CONVERT:
14241 /* Can't handle conversions from non-integral or wider integral type. */
14246 /* NOWRAP only extends to operations in the outermost type so
14247 make sure to strip it off here. */
14262 SIGNED);
14268 {
14271 /* Check for special cases to see if top is defined as multiple
14272 of bottom:
14274 top = (X & ~(bottom - 1) ; bottom is power of 2
14276 or
14278 Y = X % bottom
14279 top = X - Y. */
14298 }
14300 /* fall through */
14308 }
14309 }
14311 /* Return true if expression X cannot be (or contain) a NaN or infinity.
14312 This function returns true for integer expressions, and returns
14313 false if uncertain. */
14315 bool
14317 {
14322 {
14345 {
14346 CASE_CFN_FABS:
14348 CASE_CFN_FMAX:
14349 CASE_CFN_FMIN:
14354 }
14358 }
14359 }
14361 /* Return true if expression X evaluates to an infinity.
14362 This function returns false for integer expressions. */
14364 bool
14366 {
14370 {
14383 }
14384 }
14386 /* Return true if expression X could evaluate to an infinity.
14387 This function returns false for integer expressions, and returns
14388 true if uncertain. */
14390 bool
14392 {
14396 {
14409 }
14410 }
14412 /* Return true if expression X evaluates to a signaling NaN.
14413 This function returns false for integer expressions. */
14415 bool
14417 {
14421 {
14432 }
14433 }
14435 /* Return true if expression X could evaluate to a signaling NaN.
14436 This function returns false for integer expressions, and returns
14437 true if uncertain. */
14439 bool
14441 {
14445 {
14465 {
14466 CASE_CFN_FABS:
14468 CASE_CFN_FMAX:
14469 CASE_CFN_FMIN:
14474 }
14477 }
14478 }
14480 /* Return true if expression X evaluates to a NaN.
14481 This function returns false for integer expressions. */
14483 bool
14485 {
14489 {
14500 }
14501 }
14503 /* Return true if expression X could evaluate to a NaN.
14504 This function returns false for integer expressions, and returns
14505 true if uncertain. */
14507 bool
14509 {
14513 {
14538 {
14539 CASE_CFN_FABS:
14541 CASE_CFN_FMAX:
14542 CASE_CFN_FMIN:
14547 }
14550 }
14551 }
14553 /* Return true if expression X could evaluate to -0.0.
14554 This function returns true if uncertain. */
14556 bool
14558 {
14562 {
14577 {
14578 CASE_CFN_FABS:
14582 }
14585 }
14586 /* Ideally !(tree_expr_nonzero_p (X) || tree_expr_nonnegative_p (X))
14587 * but currently those predicates require tree and not const_tree. */
14589 }
14591 #define tree_expr_nonnegative_warnv_p(X, Y) \
14594 #define RECURSE(X) \
14595 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
14597 /* Return true if CODE or TYPE is known to be non-negative. */
14599 static bool
14601 {
14604 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14605 have a signed:1 type (where the value is -1 and 0). */
14608 }
14610 /* Return true if (CODE OP0) is known to be non-negative. If the return
14611 value is based on the assumption that signed overflow is undefined,
14612 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14613 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14615 bool
14618 {
14623 {
14625 /* We can't return 1 if flag_wrapv is set because
14626 ABS_EXPR<INT_MIN> = INT_MIN. */
14630 {
14633 }
14641 CASE_CONVERT:
14642 {
14647 {
14651 {
14655 }
14656 }
14658 {
14664 }
14665 }
14670 }
14672 /* We don't know sign of `t', so be conservative and return false. */
14674 }
14676 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14677 value is based on the assumption that signed overflow is undefined,
14678 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14679 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14681 bool
14685 {
14690 {
14696 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14697 both unsigned and at least 2 bits shorter than the result. */
14701 {
14706 {
14710 }
14711 }
14716 {
14717 /* x * x is always non-negative for floating point x
14718 or without overflow. */
14721 {
14726 }
14727 }
14729 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14730 both unsigned and their total bits is shorter than the result. */
14734 {
14753 {
14763 }
14764 }
14771 /* Usually RECURSE (op0) || RECURSE (op1) but NaNs complicate
14772 things. */
14797 }
14799 /* We don't know sign of `t', so be conservative and return false. */
14801 }
14803 /* Return true if T is known to be non-negative. If the return
14804 value is based on the assumption that signed overflow is undefined,
14805 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14806 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14808 bool
14810 {
14815 {
14829 /* Limit the depth of recursion to avoid quadratic behavior.
14830 This is expected to catch almost all occurrences in practice.
14831 If this code misses important cases that unbounded recursion
14832 would not, passes that need this information could be revised
14833 to provide it through dataflow propagation. */
14841 }
14842 }
14844 /* Return true if T is known to be non-negative. If the return
14845 value is based on the assumption that signed overflow is undefined,
14846 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14847 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14849 bool
14852 {
14854 {
14855 CASE_CFN_ACOS:
14856 CASE_CFN_ACOSH:
14857 CASE_CFN_CABS:
14858 CASE_CFN_COSH:
14859 CASE_CFN_ERFC:
14860 CASE_CFN_EXP:
14861 CASE_CFN_EXP10:
14862 CASE_CFN_EXP2:
14863 CASE_CFN_FABS:
14864 CASE_CFN_FDIM:
14865 CASE_CFN_HYPOT:
14866 CASE_CFN_POW10:
14867 CASE_CFN_FFS:
14868 CASE_CFN_PARITY:
14869 CASE_CFN_POPCOUNT:
14870 CASE_CFN_CLZ:
14871 CASE_CFN_CLRSB:
14876 /* Always true. */
14879 CASE_CFN_SQRT:
14880 CASE_CFN_SQRT_FN:
14881 /* sqrt(-0.0) is -0.0. */
14886 CASE_CFN_ASINH:
14887 CASE_CFN_ATAN:
14888 CASE_CFN_ATANH:
14889 CASE_CFN_CBRT:
14890 CASE_CFN_CEIL:
14891 CASE_CFN_CEIL_FN:
14892 CASE_CFN_ERF:
14893 CASE_CFN_EXPM1:
14894 CASE_CFN_FLOOR:
14895 CASE_CFN_FLOOR_FN:
14896 CASE_CFN_FMOD:
14897 CASE_CFN_FREXP:
14898 CASE_CFN_ICEIL:
14899 CASE_CFN_IFLOOR:
14900 CASE_CFN_IRINT:
14901 CASE_CFN_IROUND:
14902 CASE_CFN_LCEIL:
14903 CASE_CFN_LDEXP:
14904 CASE_CFN_LFLOOR:
14905 CASE_CFN_LLCEIL:
14906 CASE_CFN_LLFLOOR:
14907 CASE_CFN_LLRINT:
14908 CASE_CFN_LLROUND:
14909 CASE_CFN_LRINT:
14910 CASE_CFN_LROUND:
14911 CASE_CFN_MODF:
14912 CASE_CFN_NEARBYINT:
14913 CASE_CFN_NEARBYINT_FN:
14914 CASE_CFN_RINT:
14915 CASE_CFN_RINT_FN:
14916 CASE_CFN_ROUND:
14917 CASE_CFN_ROUND_FN:
14918 CASE_CFN_ROUNDEVEN:
14919 CASE_CFN_ROUNDEVEN_FN:
14920 CASE_CFN_SCALB:
14921 CASE_CFN_SCALBLN:
14922 CASE_CFN_SCALBN:
14923 CASE_CFN_SIGNBIT:
14924 CASE_CFN_SIGNIFICAND:
14925 CASE_CFN_SINH:
14926 CASE_CFN_TANH:
14927 CASE_CFN_TRUNC:
14928 CASE_CFN_TRUNC_FN:
14929 /* True if the 1st argument is nonnegative. */
14932 CASE_CFN_FMAX:
14933 CASE_CFN_FMAX_FN:
14934 /* Usually RECURSE (arg0) || RECURSE (arg1) but NaNs complicate
14935 things. In the presence of sNaNs, we're only guaranteed to be
14936 non-negative if both operands are non-negative. In the presence
14937 of qNaNs, we're non-negative if either operand is non-negative
14938 and can't be a qNaN, or if both operands are non-negative. */
14947 CASE_CFN_FMIN:
14948 CASE_CFN_FMIN_FN:
14949 /* True if the 1st AND 2nd arguments are nonnegative. */
14952 CASE_CFN_COPYSIGN:
14953 CASE_CFN_COPYSIGN_FN:
14954 /* True if the 2nd argument is nonnegative. */
14957 CASE_CFN_POWI:
14958 /* True if the 1st argument is nonnegative or the second
14959 argument is an even integer. */
14965 CASE_CFN_POW:
14966 /* True if the 1st argument is nonnegative or the second
14967 argument is an even integer valued real. */
14969 {
14970 REAL_VALUE_TYPE c;
14971 HOST_WIDE_INT n;
14976 {
14977 REAL_VALUE_TYPE cint;
14981 }
14982 }
14987 }
14989 }
14991 /* Return true if T is known to be non-negative. If the return
14992 value is based on the assumption that signed overflow is undefined,
14993 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14994 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14996 static bool
14998 {
15004 {
15006 {
15010 /* If the initializer is non-void, then it's a normal expression
15011 that will be assigned to the slot. */
15015 /* Otherwise, the initializer sets the slot in some way. One common
15016 way is an assignment statement at the end of the initializer. */
15018 {
15026 else
15028 }
15034 }
15037 {
15043 arg0,
15044 arg1,
15046 }
15059 }
15060 }
15062 #undef RECURSE
15063 #undef tree_expr_nonnegative_warnv_p
15065 /* Return true if T is known to be non-negative. If the return
15066 value is based on the assumption that signed overflow is undefined,
15067 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15068 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
15070 bool
15072 {
15079 {
15101 }
15104 {
15130 }
15131 }
15133 /* Return true if `t' is known to be non-negative. Handle warnings
15134 about undefined signed overflow. */
15136 bool
15138 {
15145 "determining that expression is always "
15147 WARN_STRICT_OVERFLOW_MISC);
15149 }
15152 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15153 For floating point we further ensure that T is not denormal.
15154 Similar logic is present in nonzero_address in rtlanal.h.
15156 If the return value is based on the assumption that signed overflow
15157 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15158 change *STRICT_OVERFLOW_P. */
15160 bool
15163 {
15165 {
15168 strict_overflow_p);
15171 {
15177 strict_overflow_p));
15178 }
15183 strict_overflow_p);
15187 }
15190 }
15192 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15193 For floating point we further ensure that T is not denormal.
15194 Similar logic is present in nonzero_address in rtlanal.h.
15196 If the return value is based on the assumption that signed overflow
15197 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15198 change *STRICT_OVERFLOW_P. */
15200 bool
15202 tree type,
15203 tree op0,
15205 {
15208 {
15212 {
15213 /* With the presence of negative values it is hard
15214 to say something. */
15221 /* One of operands must be positive and the other non-negative. */
15222 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15223 overflows, on a twos-complement machine the sum of two
15224 nonnegative numbers can never be zero. */
15226 strict_overflow_p)
15228 strict_overflow_p));
15229 }
15234 {
15236 strict_overflow_p)
15238 strict_overflow_p))
15239 {
15242 }
15243 }
15252 {
15255 }
15262 {
15266 /* When both operands are nonzero, then MAX must be too. */
15268 strict_overflow_p))
15271 /* MAX where operand 0 is positive is positive. */
15273 strict_overflow_p);
15274 }
15275 /* MAX where operand 1 is positive is positive. */
15280 {
15284 }
15289 strict_overflow_p)
15291 strict_overflow_p));
15295 }
15298 }
15300 /* Return true when T is an address and is known to be nonzero.
15301 For floating point we further ensure that T is not denormal.
15302 Similar logic is present in nonzero_address in rtlanal.h.
15304 If the return value is based on the assumption that signed overflow
15305 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15306 change *STRICT_OVERFLOW_P. */
15308 bool
15310 {
15313 {
15318 {
15330 /* For objects in symbol table check if we know they are non-zero.
15331 Don't do anything for variables and functions before symtab is built;
15332 it is quite possible that they will be declared weak later. */
15337 /* Constants are never weak. */
15342 }
15350 {
15354 }
15364 }
15366 }
15368 #define integer_valued_real_p(X) \
15371 #define RECURSE(X) \
15372 ((integer_valued_real_p) (X, depth + 1))
15374 /* Return true if the floating point result of (CODE OP0) has an
15375 integer value. We also allow +Inf, -Inf and NaN to be considered
15376 integer values. Return false for signaling NaN.
15378 DEPTH is the current nesting depth of the query. */
15380 bool
15382 {
15384 {
15391 CASE_CONVERT:
15392 {
15399 }
15403 }
15405 }
15407 /* Return true if the floating point result of (CODE OP0 OP1) has an
15408 integer value. We also allow +Inf, -Inf and NaN to be considered
15409 integer values. Return false for signaling NaN.
15411 DEPTH is the current nesting depth of the query. */
15413 bool
15415 {
15417 {
15427 }
15429 }
15431 /* Return true if the floating point result of calling FNDECL with arguments
15432 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
15433 considered integer values. Return false for signaling NaN. If FNDECL
15434 takes fewer than 2 arguments, the remaining ARGn are null.
15436 DEPTH is the current nesting depth of the query. */
15438 bool
15440 {
15442 {
15443 CASE_CFN_CEIL:
15444 CASE_CFN_CEIL_FN:
15445 CASE_CFN_FLOOR:
15446 CASE_CFN_FLOOR_FN:
15447 CASE_CFN_NEARBYINT:
15448 CASE_CFN_NEARBYINT_FN:
15449 CASE_CFN_RINT:
15450 CASE_CFN_RINT_FN:
15451 CASE_CFN_ROUND:
15452 CASE_CFN_ROUND_FN:
15453 CASE_CFN_ROUNDEVEN:
15454 CASE_CFN_ROUNDEVEN_FN:
15455 CASE_CFN_TRUNC:
15456 CASE_CFN_TRUNC_FN:
15459 CASE_CFN_FMIN:
15460 CASE_CFN_FMIN_FN:
15461 CASE_CFN_FMAX:
15462 CASE_CFN_FMAX_FN:
15467 }
15469 }
15471 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
15472 has an integer value. We also allow +Inf, -Inf and NaN to be
15473 considered integer values. Return false for signaling NaN.
15475 DEPTH is the current nesting depth of the query. */
15477 bool
15479 {
15481 {
15489 /* Limit the depth of recursion to avoid quadratic behavior.
15490 This is expected to catch almost all occurrences in practice.
15491 If this code misses important cases that unbounded recursion
15492 would not, passes that need this information could be revised
15493 to provide it through dataflow propagation. */
15497 depth));
15501 }
15503 }
15505 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
15506 has an integer value. We also allow +Inf, -Inf and NaN to be
15507 considered integer values. Return false for signaling NaN.
15509 DEPTH is the current nesting depth of the query. */
15511 static bool
15513 {
15515 {
15526 }
15528 }
15530 #undef RECURSE
15531 #undef integer_valued_real_p
15533 /* Return true if the floating point expression T has an integer value.
15534 We also allow +Inf, -Inf and NaN to be considered integer values.
15535 Return false for signaling NaN.
15537 DEPTH is the current nesting depth of the query. */
15539 bool
15541 {
15549 {
15565 }
15568 {
15574 {
15583 }
15587 }
15588 }
15590 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15591 attempt to fold the expression to a constant without modifying TYPE,
15592 OP0 or OP1.
15594 If the expression could be simplified to a constant, then return
15595 the constant. If the expression would not be simplified to a
15596 constant, then return NULL_TREE. */
15598 tree
15600 {
15603 }
15605 /* Given the components of a unary expression CODE, TYPE and OP0,
15606 attempt to fold the expression to a constant without modifying
15607 TYPE or OP0.
15609 If the expression could be simplified to a constant, then return
15610 the constant. If the expression would not be simplified to a
15611 constant, then return NULL_TREE. */
15613 tree
15615 {
15618 }
15620 /* If EXP represents referencing an element in a constant string
15621 (either via pointer arithmetic or array indexing), return the
15622 tree representing the value accessed, otherwise return NULL. */
15624 tree
15626 {
15630 {
15632 tree index;
15633 tree string;
15638 else
15639 {
15643 /* Optimize the special-case of a zero lower bound.
15645 We convert the low_bound to sizetype to avoid some problems
15646 with constant folding. (E.g. suppose the lower bound is 1,
15647 and its mode is QI. Without the conversion,l (ARRAY
15648 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15649 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15655 }
15657 scalar_int_mode char_mode;
15669 }
15671 }
15673 /* Folds a read from vector element at IDX of vector ARG. */
15675 tree
15677 {
15682 {
15686 {
15693 }
15694 }
15696 }
15698 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15699 an integer constant, real, or fixed-point constant.
15701 TYPE is the type of the result. */
15703 static tree
15705 {
15709 {
15715 {
15716 FIXED_VALUE_TYPE f;
15721 /* Propagate overflow flags. */
15725 }
15729 {
15736 }
15739 }
15742 }
15744 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15745 an integer constant or real constant.
15747 TYPE is the type of the result. */
15749 tree
15751 {
15755 {
15757 {
15758 /* If the value is unsigned or non-negative, then the absolute value
15759 is the same as the ordinary value. */
15763 ;
15765 /* If the value is negative, then the absolute value is
15766 its negation. */
15767 else
15770 /* Force to the destination type, set TREE_OVERFLOW for signed
15771 TYPE only. */
15773 }
15779 else
15785 }
15788 }
15790 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15791 constant. TYPE is the type of the result. */
15793 static tree
15795 {
15799 }
15801 /* Given CODE, a relational operator, the target type, TYPE and two
15802 constant operands OP0 and OP1, return the result of the
15803 relational operation. If the result is not a compile time
15804 constant, then return NULL_TREE. */
15806 static tree
15808 {
15811 /* From here on, the only cases we handle are when the result is
15812 known to be a constant. */
15815 {
15819 /* Handle the cases where either operand is a NaN. */
15821 {
15823 {
15851 }
15854 }
15857 }
15860 {
15864 }
15866 /* Handle equality/inequality of complex constants. */
15868 {
15879 else
15881 }
15884 {
15886 {
15887 /* Have vector comparison with scalar boolean result. */
15895 {
15903 }
15905 }
15906 tree_vector_builder elts;
15911 {
15924 }
15927 }
15929 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15931 To compute GT, swap the arguments and do LT.
15932 To compute GE, do LT and invert the result.
15933 To compute LE, swap the arguments, do LT and invert the result.
15934 To compute NE, do EQ and invert the result.
15936 Therefore, the code below must handle only EQ and LT. */
15939 {
15942 }
15944 /* Note that it is safe to invert for real values here because we
15945 have already handled the one case that it matters. */
15949 {
15952 }
15954 /* Compute a result for LT or EQ if args permit;
15955 Otherwise return T. */
15957 {
15960 else
15962 }
15963 else
15969 }
15971 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15972 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15973 itself. */
15975 tree
15977 {
15978 /* If the expression does not have side effects then we don't have to wrap
15979 it with a cleanup point expression. */
15983 /* If the expression is a return, check to see if the expression inside the
15984 return has no side effects or the right hand side of the modify expression
15985 inside the return. If either don't have side effects set we don't need to
15986 wrap the expression in a cleanup point expression. Note we don't check the
15987 left hand side of the modify because it should always be a return decl. */
15989 {
15996 }
15999 }
16001 /* Given a pointer value OP0 and a type TYPE, return a simplified version
16002 of an indirection through OP0, or NULL_TREE if no simplification is
16003 possible. */
16005 tree
16007 {
16009 tree subtype;
16010 poly_uint64 const_op01;
16019 {
16023 /* *&CONST_DECL -> to the value of the const decl. */
16026 /* *&p => p; make sure to handle *&"str"[cst] here. */
16028 {
16032 else
16034 }
16035 /* *(foo *)&fooarray => fooarray[0] */
16038 && (!in_gimple_form
16040 {
16050 }
16051 /* *(foo *)&complexfoo => __real__ complexfoo */
16055 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16058 {
16062 index);
16063 }
16064 }
16068 {
16074 {
16075 tree op00type;
16079 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16082 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
16083 but we want to treat offsets with MSB set as negative.
16084 For the code below negative offsets are invalid and
16085 TYPE_SIZE of the element is something unsigned, so
16086 check whether op01 fits into poly_int64, which implies
16087 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
16088 then just use poly_uint64 because we want to treat the
16089 value as unsigned. */
16091 {
16093 poly_uint64 max_offset
16097 {
16102 }
16103 }
16104 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16107 {
16109 const_op01))
16111 }
16112 /* ((foo *)&fooarray)[1] => fooarray[1] */
16115 {
16124 {
16129 }
16130 }
16131 }
16132 }
16134 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16137 && (!in_gimple_form
16139 {
16140 tree type_domain;
16150 NULL_TREE);
16151 }
16154 }
16156 /* Builds an expression for an indirection through T, simplifying some
16157 cases. */
16159 tree
16161 {
16169 }
16171 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16173 tree
16175 {
16180 else
16182 }
16184 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16185 whose result is ignored. The type of the returned tree need not be
16186 the same as the original expression. */
16188 tree
16190 {
16196 {
16207 else
16213 {
16229 }
16234 }
16235 }
16237 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16239 tree
16241 {
16247 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16248 have to do anything. Only do this when we are not given a const,
16249 because in that case, this check is more expensive than just
16250 doing it. */
16252 {
16257 }
16259 /* If divisor is a power of two, simplify this to bit manipulation. */
16261 {
16263 {
16277 }
16278 else
16279 {
16280 tree t;
16286 }
16287 }
16288 else
16289 {
16294 }
16297 }
16299 /* Likewise, but round down. */
16301 tree
16303 {
16310 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16311 have to do anything. Only do this when we are not given a const,
16312 because in that case, this check is more expensive than just
16313 doing it. */
16315 {
16320 }
16322 /* If divisor is a power of two, simplify this to bit manipulation. */
16324 {
16325 tree t;
16329 }
16330 else
16331 {
16336 }
16339 }
16341 /* Returns the pointer to the base of the object addressed by EXP and
16342 extracts the information about the offset of the access, storing it
16343 to PBITPOS and POFFSET. */
16345 static tree
16348 {
16349 tree core;
16350 machine_mode mode;
16352 poly_int64 bitsize;
16356 {
16361 }
16363 {
16369 {
16370 poly_offset_int tem
16376 }
16377 }
16378 else
16379 {
16383 }
16386 }
16388 /* Returns true if addresses of E1 and E2 differ by a constant, false
16389 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16391 bool
16393 {
16408 {
16418 }
16420 {
16421 /* If only one of the offsets is non-constant, the difference cannot
16422 be a constant. */
16424 }
16425 else
16430 }
16432 /* Return OFF converted to a pointer offset type suitable as offset for
16433 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16434 tree
16436 {
16440 }
16442 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16443 tree
16445 {
16448 }
16450 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16451 tree
16453 {
16456 }
16458 /* Return a pointer to a NUL-terminated string containing the sequence
16459 of bytes corresponding to the representation of the object referred to
16460 by SRC (or a subsequence of such bytes within it if SRC is a reference
16461 to an initialized constant array plus some constant offset).
16462 Set *STRSIZE the number of bytes in the constant sequence including
16463 the terminating NUL byte. *STRSIZE is equal to sizeof(A) - OFFSET
16464 where A is the array that stores the constant sequence that SRC points
16465 to and OFFSET is the byte offset of SRC from the beginning of A. SRC
16466 need not point to a string or even an array of characters but may point
16467 to an object of any type. */
16471 {
16472 /* The offset into the array A storing the string, and A's byte size. */
16473 tree offset_node;
16474 tree mem_size;
16481 else
16488 {
16491 else
16493 }
16498 /* ARRAY_SIZE is the byte size of the array the constant sequence
16499 is stored in and equal to sizeof A. INIT_BYTES is the number
16500 of bytes in the constant sequence used to initialize the array,
16501 including any embedded NULs as well as the terminating NUL (for
16502 strings), but not including any trailing zeros/NULs past
16503 the terminating one appended implicitly to a string literal to
16504 zero out the remainder of the array it's stored in. For example,
16505 given:
16506 const char a[7] = "abc\0d";
16507 n = strlen (a + 1);
16508 ARRAY_SIZE is 7, INIT_BYTES is 6, and OFFSET is 1. For a valid
16509 (i.e., nul-terminated) string with no embedded nuls, INIT_BYTES
16510 is equal to strlen (A) + 1. */
16515 /* Ideally this would turn into a gcc_checking_assert over time. */
16523 {
16524 /* Compute and store the number of characters from the beginning
16525 of the substring at OFFSET to the end, including the terminating
16526 nul. Offsets past the initial length refer to null strings. */
16529 else
16531 }
16532 else
16533 {
16535 /* Support only properly NUL-terminated single byte strings. */
16540 }
16543 }
16545 /* Return a pointer to a NUL-terminated string corresponding to
16546 the expression STR referencing a constant string, possibly
16547 involving a constant offset. Return null if STR either doesn't
16548 reference a constant string or if it involves a nonconstant
16549 offset. */
16553 {
16555 }
16557 /* Given a tree T, compute which bits in T may be nonzero. */
16559 wide_int
16561 {
16563 {
16581 CASE_CONVERT:
16587 {
16592 }
16596 {
16604 }
16608 {
16616 }
16620 }
16623 }
16625 /* Helper function for address compare simplifications in match.pd.
16626 OP0 and OP1 are ADDR_EXPR operands being compared by CODE.
16627 TYPE is the type of comparison operands.
16628 BASE0, BASE1, OFF0 and OFF1 are set by the function.
16629 GENERIC is true if GENERIC folding and false for GIMPLE folding.
16630 Returns 0 if OP0 is known to be unequal to OP1 regardless of OFF{0,1},
16631 1 if bases are known to be equal and OP0 cmp OP1 depends on OFF0 cmp OFF1,
16632 and 2 if unknown. */
16634 int
16638 {
16644 {
16647 }
16649 {
16652 }
16657 /* Punt in GENERIC on variables with value expressions;
16658 the value expressions might point to fields/elements
16659 of other vars etc. */
16665 {
16669 }
16677 /* Assume different STRING_CSTs with the same content will be
16678 merged. */
16687 {
16690 /* If the offsets are equal we can ignore overflow. */
16693 /* Or if we compare using pointers to decls or strings. */
16698 }
16704 /* At this point we know (or assume) the two pointers point at
16705 different objects. */
16709 /* Punt on non-zero offsets from functions. */
16713 /* Or if the bases are neither decls nor string literals. */
16718 /* For initializers, assume addresses of different functions are
16719 different. */
16725 /* Compute whether one address points to the start of one
16726 object and another one to the end of another one. */
16729 {
16732 else
16734 }
16737 else
16738 {
16742 else
16744 }
16746 {
16749 else
16751 }
16754 else
16755 {
16759 else
16761 }
16763 {
16764 /* If one offset is pointing (or could be) to the beginning of one
16765 object and the other is pointing to one past the last byte of the
16766 other object, punt. */
16771 /* If both offsets are the same, there are some cases we know that are
16772 ok. Either if we know they aren't zero, or if we know both sizes
16773 are no zero. */
16779 }
16781 /* At this point, equal is 2 if either one or both pointers are out of
16782 bounds of their object, or one points to start of its object and the
16783 other points to end of its object. This is unspecified behavior
16784 e.g. in C++. Otherwise equal is 0. */
16788 /* When both pointers point to string literals, even when equal is 0,
16789 due to tail merging of string literals the pointers might be the same. */
16791 {
16798 /* If the bytes in the string literals starting at the pointers
16799 differ, the pointers need to be different. */
16804 {
16809 /* If even the bytes in the string literal before the
16810 pointers are the same, the string literals could be
16811 tail merged. */
16813 }
16815 }
16820 /* If this is a pointer comparison, ignore for now even
16821 valid equalities where one pointer is the offset zero
16822 of one object and the other to one past end of another one. */
16826 /* Assume that string literals can't be adjacent to variables
16827 (automatic or global). */
16831 /* Assume that automatic variables can't be adjacent to global
16832 variables. */
16837 }
16839 /* Return the single non-zero element of a CONSTRUCTOR or NULL_TREE. */
16840 tree
16842 {
16851 {
16855 }
16857 }
16859 #if CHECKING_P
16863 /* Helper functions for writing tests of folding trees. */
16865 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
16867 static void
16869 tree constant)
16870 {
16872 }
16874 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
16875 wrapping WRAPPED_EXPR. */
16877 static void
16879 tree wrapped_expr)
16880 {
16885 }
16887 /* Verify that various arithmetic binary operations are folded
16888 correctly. */
16890 static void
16892 {
16898 /* Addition. */
16899 /* 1 <-- (0 + 1) */
16901 one);
16903 one);
16905 /* (nonlvalue)x <-- (x + 0) */
16907 x);
16909 /* Subtraction. */
16910 /* 0 <-- (x - x) */
16912 zero);
16914 x);
16916 /* Multiplication. */
16917 /* 0 <-- (x * 0) */
16919 zero);
16921 /* (nonlvalue)x <-- (x * 1) */
16923 x);
16924 }
16926 /* Verify that various binary operations on vectors are folded
16927 correctly. */
16929 static void
16931 {
16938 /* Verify equality tests that return a scalar boolean result. */
16951 }
16953 /* Verify folding of VEC_DUPLICATE_EXPRs. */
16955 static void
16957 {
16960 /* This will be 1 if VEC_MODE isn't a vector mode. */
16967 }
16969 /* Run all of the selftests within this file. */
16971 void
16973 {
16977 }