| blob | 0b9a42f764ac4b02c7acd1eee5f2a930024f5150 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2021 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. */
88 /* Nonzero if we are folding constants inside an initializer or a C++
89 manifestly-constant-evaluated context; zero otherwise. */
92 /* The following constants represent a bit based encoding of GCC's
93 comparison operators. This encoding simplifies transformations
94 on relational comparison operators, such as AND and OR. */
112 };
146 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
147 Otherwise, return LOC. */
149 static location_t
151 {
154 }
156 /* Similar to protected_set_expr_location, but never modify x in place,
157 if location can and needs to be set, unshare it. */
161 {
167 {
170 }
172 }
173 \f
174 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
175 division and returns the quotient. Otherwise returns
176 NULL_TREE. */
178 tree
180 {
181 widest_int quo;
188 }
189 \f
190 /* This is nonzero if we should defer warnings about undefined
191 overflow. This facility exists because these warnings are a
192 special case. The code to estimate loop iterations does not want
193 to issue any warnings, since it works with expressions which do not
194 occur in user code. Various bits of cleanup code call fold(), but
195 only use the result if it has certain characteristics (e.g., is a
196 constant); that code only wants to issue a warning if the result is
197 used. */
201 /* If a warning about undefined overflow is deferred, this is the
202 warning. Note that this may cause us to turn two warnings into
203 one, but that is fine since it is sufficient to only give one
204 warning per expression. */
208 /* If a warning about undefined overflow is deferred, this is the
209 level at which the warning should be emitted. */
213 /* Start deferring overflow warnings. We could use a stack here to
214 permit nested calls, but at present it is not necessary. */
216 void
218 {
220 }
222 /* Stop deferring overflow warnings. If there is a pending warning,
223 and ISSUE is true, then issue the warning if appropriate. STMT is
224 the statement with which the warning should be associated (used for
225 location information); STMT may be NULL. CODE is the level of the
226 warning--a warn_strict_overflow_code value. This function will use
227 the smaller of CODE and the deferred code when deciding whether to
228 issue the warning. CODE may be zero to mean to always use the
229 deferred code. */
231 void
233 {
235 location_t locus;
240 {
246 }
257 /* Use the smallest code level when deciding to issue the
258 warning. */
267 else
270 }
272 /* Stop deferring overflow warnings, ignoring any deferred
273 warnings. */
275 void
277 {
279 }
281 /* Whether we are deferring overflow warnings. */
283 bool
285 {
287 }
289 /* This is called when we fold something based on the fact that signed
290 overflow is undefined. */
292 void
294 {
296 {
299 {
302 }
303 }
306 }
307 \f
308 /* Return true if the built-in mathematical function specified by CODE
309 is odd, i.e. -f(x) == f(-x). */
311 bool
313 {
315 {
316 CASE_CFN_ASIN:
317 CASE_CFN_ASINH:
318 CASE_CFN_ATAN:
319 CASE_CFN_ATANH:
320 CASE_CFN_CASIN:
321 CASE_CFN_CASINH:
322 CASE_CFN_CATAN:
323 CASE_CFN_CATANH:
324 CASE_CFN_CBRT:
325 CASE_CFN_CPROJ:
326 CASE_CFN_CSIN:
327 CASE_CFN_CSINH:
328 CASE_CFN_CTAN:
329 CASE_CFN_CTANH:
330 CASE_CFN_ERF:
331 CASE_CFN_LLROUND:
332 CASE_CFN_LROUND:
333 CASE_CFN_ROUND:
334 CASE_CFN_ROUNDEVEN:
335 CASE_CFN_ROUNDEVEN_FN:
336 CASE_CFN_SIN:
337 CASE_CFN_SINH:
338 CASE_CFN_TAN:
339 CASE_CFN_TANH:
340 CASE_CFN_TRUNC:
343 CASE_CFN_LLRINT:
344 CASE_CFN_LRINT:
345 CASE_CFN_NEARBYINT:
346 CASE_CFN_RINT:
351 }
353 }
355 /* Check whether we may negate an integer constant T without causing
356 overflow. */
358 bool
360 {
361 tree type;
370 }
372 /* Determine whether an expression T can be cheaply negated using
373 the function negate_expr without introducing undefined overflow. */
375 static bool
377 {
378 tree type;
387 {
392 /* Check that -CST will not overflow type. */
405 /* We want to canonicalize to positive real constants. Pretend
406 that only negative ones can be easily negated. */
414 {
418 /* Steps don't prevent negation. */
425 }
440 /* -(A + B) -> (-B) - A. */
443 /* -(A + B) -> (-A) - B. */
447 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
456 /* INT_MIN/n * n doesn't overflow while negating one operand it does
457 if n is a (negative) power of two. */
468 /* Fall through. */
481 /* In general we can't negate A in A / B, because if A is INT_MIN and
482 B is not 1 we change the sign of the result. */
486 /* In general we can't negate B in A / B, because if A is INT_MIN and
487 B is 1, we may turn this into INT_MIN / -1 which is undefined
488 and actually traps on some architectures. */
497 /* Negate -((double)float) as (double)(-float). */
499 {
503 }
507 /* Negate -f(x) as f(-x). */
513 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
515 {
519 }
524 }
526 }
528 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
529 simplification is possible.
530 If negate_expr_p would return true for T, NULL_TREE will never be
531 returned. */
533 static tree
535 {
537 tree tem;
540 {
541 /* Convert - (~A) to A + 1. */
565 {
570 }
574 {
575 tree_vector_builder elts;
579 {
584 }
587 }
610 {
611 /* -(A + B) -> (-B) - A. */
613 {
617 }
619 /* -(A + B) -> (-A) - B. */
621 {
625 }
626 }
630 /* - (A - B) -> B - A */
641 /* Fall through. */
645 {
654 }
662 /* In general we can't negate A in A / B, because if A is INT_MIN and
663 B is not 1 we change the sign of the result. */
669 /* In general we can't negate B in A / B, because if A is INT_MIN and
670 B is 1, we may turn this into INT_MIN / -1 which is undefined
671 and actually traps on some architectures. */
683 /* Convert -((double)float) into (double)(-float). */
685 {
689 }
693 /* Negate -f(x) as f(-x). */
696 {
702 }
706 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
708 {
711 {
718 }
719 }
724 }
727 }
729 /* A wrapper for fold_negate_expr_1. */
731 static tree
733 {
740 }
742 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T cannot be
743 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
744 return NULL_TREE. */
746 static tree
748 {
750 location_t loc;
763 }
764 \f
765 /* Split a tree IN into a constant, literal and variable parts that could be
766 combined with CODE to make IN. "constant" means an expression with
767 TREE_CONSTANT but that isn't an actual constant. CODE must be a
768 commutative arithmetic operation. Store the constant part into *CONP,
769 the literal in *LITP and return the variable part. If a part isn't
770 present, set it to null. If the tree does not decompose in this way,
771 return the entire tree as the variable part and the other parts as null.
773 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
774 case, we negate an operand that was subtracted. Except if it is a
775 literal for which we use *MINUS_LITP instead.
777 If NEGATE_P is true, we are negating all of IN, again except a literal
778 for which we use *MINUS_LITP instead. If a variable part is of pointer
779 type, it is negated after converting to TYPE. This prevents us from
780 generating illegal MINUS pointer expression. LOC is the location of
781 the converted variable part.
783 If IN is itself a literal or constant, return it as appropriate.
785 Note that we do not guarantee that any of the three values will be the
786 same type as IN, but they will have the same signedness and mode. */
788 static tree
792 {
800 /* Strip any conversions that don't change the machine mode or signedness. */
809 /* We can associate addition and subtraction together (even
810 though the C standard doesn't say so) for integers because
811 the value is not affected. For reals, the value might be
812 affected, so we can't. */
818 {
824 /* First see if either of the operands is a literal, then a constant. */
837 /* If we haven't dealt with either operand, this is not a case we can
838 decompose. Otherwise, VAR is either of the ones remaining, if any. */
843 else
846 /* Now do any needed negations. */
853 }
858 {
859 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
860 when IN is constant. */
863 }
864 else
868 {
881 }
891 }
893 /* Re-associate trees split by the above function. T1 and T2 are
894 either expressions to associate or null. Return the new
895 expression, if any. LOC is the location of the new expression. If
896 we build an operation, do it in TYPE and with CODE. */
898 static tree
900 {
902 {
905 }
909 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
910 try to fold this since we will have infinite recursion. But do
911 deal with any NEGATE_EXPRs. */
915 {
917 {
930 }
932 {
935 }
939 }
943 }
944 \f
945 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
946 for use in int_const_binop, size_binop and size_diffop. */
948 static bool
950 {
957 {
966 }
971 }
973 /* Combine two wide ints ARG1 and ARG2 under operation CODE to produce
974 a new constant in RES. Return FALSE if we don't know how to
975 evaluate CODE at compile-time. */
977 bool
981 {
982 wide_int tmp;
985 {
1007 /* It's unclear from the C standard whether shifts can overflow.
1008 The following code ignores overflow; perhaps a C standard
1009 interpretation ruling is needed. */
1016 {
1020 else
1022 }
1023 else
1028 else
1107 }
1109 }
1111 /* Combine two poly int's ARG1 and ARG2 under operation CODE to
1112 produce a new constant in RES. Return FALSE if we don't know how
1113 to evaluate CODE at compile-time. */
1115 static bool
1119 {
1123 {
1141 else
1148 else
1161 }
1163 }
1165 /* Combine two integer constants ARG1 and ARG2 under operation CODE to
1166 produce a new constant. Return NULL_TREE if we don't know how to
1167 evaluate CODE at compile-time. */
1169 tree
1172 {
1173 poly_wide_int poly_res;
1179 {
1185 }
1194 }
1196 /* Return true if binary operation OP distributes over addition in operand
1197 OPNO, with the other operand being held constant. OPNO counts from 1. */
1199 static bool
1201 {
1203 {
1214 }
1215 }
1217 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1218 constant. We assume ARG1 and ARG2 have the same data type, or at least
1219 are the same kind of constant and the same machine mode. Return zero if
1220 combining the constants is not allowed in the current operating mode. */
1222 static tree
1224 {
1225 /* Sanity check for the recursive cases. */
1233 {
1239 }
1242 {
1243 machine_mode mode;
1244 REAL_VALUE_TYPE d1;
1245 REAL_VALUE_TYPE d2;
1246 REAL_VALUE_TYPE value;
1247 REAL_VALUE_TYPE result;
1251 /* The following codes are handled by real_arithmetic. */
1253 {
1264 }
1272 /* Don't perform operation if we honor signaling NaNs and
1273 either operand is a signaling NaN. */
1279 /* Don't perform operation if it would raise a division
1280 by zero exception. */
1286 /* If either operand is a NaN, just return it. Otherwise, set up
1287 for floating-point trap; we return an overflow. */
1289 {
1290 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1291 is off. */
1295 }
1297 {
1298 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1299 is off. */
1303 }
1308 /* Don't constant fold this floating point operation if
1309 the result has overflowed and flag_trapping_math. */
1317 /* Don't constant fold this floating point operation if the
1318 result may dependent upon the run-time rounding mode and
1319 flag_rounding_math is set, or if GCC's software emulation
1320 is unable to accurately represent the result. */
1330 }
1333 {
1334 FIXED_VALUE_TYPE f1;
1335 FIXED_VALUE_TYPE f2;
1336 FIXED_VALUE_TYPE result;
1341 /* The following codes are handled by fixed_arithmetic. */
1343 {
1355 {
1362 }
1367 }
1374 /* Propagate overflow flags. */
1378 }
1381 {
1390 {
1401 mpc_mul);
1415 mpc_div);
1416 /* Fallthru. */
1422 {
1423 /* Keep this algorithm in sync with
1424 tree-complex.c:expand_complex_div_straight().
1426 Expand complex division to scalars, straightforward algorithm.
1427 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1428 t = br*br + bi*bi
1429 */
1430 tree magsquared
1434 tree t1
1438 tree t2
1445 }
1446 else
1447 {
1448 /* Keep this algorithm in sync with
1449 tree-complex.c:expand_complex_div_wide().
1451 Expand complex division to scalars, modified algorithm to minimize
1452 overflow with wide input ranges. */
1458 {
1459 /* In the TRUE branch, we compute
1460 ratio = br/bi;
1461 div = (br * ratio) + bi;
1462 tr = (ar * ratio) + ai;
1463 ti = (ai * ratio) - ar;
1464 tr = tr / div;
1465 ti = ti / div; */
1476 }
1477 else
1478 {
1479 /* In the FALSE branch, we compute
1480 ratio = d/c;
1481 divisor = (d * ratio) + c;
1482 tr = (b * ratio) + a;
1483 ti = b - (a * ratio);
1484 tr = tr / div;
1485 ti = ti / div; */
1497 }
1498 }
1503 }
1507 }
1513 {
1518 /* We can operate directly on the encoding if:
1520 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1521 implies
1522 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1524 Addition and subtraction are the supported operators
1525 for which this is true. */
1528 /* We can operate directly on stepped encodings if:
1530 a3 - a2 == a2 - a1
1531 implies:
1532 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1534 which is true if (x -> x op c) distributes over addition. */
1536 else
1537 /* Similarly in reverse. */
1539 tree_vector_builder elts;
1544 {
1550 /* It is possible that const_binop cannot handle the given
1551 code and return NULL_TREE */
1555 }
1558 }
1560 /* Shifts allow a scalar offset for a vector. */
1563 {
1566 tree_vector_builder elts;
1571 {
1576 /* It is possible that const_binop cannot handle the given
1577 code and return NULL_TREE. */
1581 }
1584 }
1586 }
1588 /* Overload that adds a TYPE parameter to be able to dispatch
1589 to fold_relational_const. */
1591 tree
1593 {
1597 /* ??? Until we make the const_binop worker take the type of the
1598 result as argument put those cases that need it here. */
1600 {
1617 {
1622 }
1628 {
1644 {
1649 ? NOP_EXPR
1656 }
1659 }
1665 {
1688 {
1701 }
1704 }
1707 }
1712 /* Make sure type and arg0 have the same saturating flag. */
1717 }
1719 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1720 Return zero if computing the constants is not possible. */
1722 tree
1724 {
1725 /* Don't perform the operation, other than NEGATE and ABS, if
1726 flag_signaling_nans is on and the operand is a signaling NaN. */
1736 {
1737 CASE_CONVERT:
1744 /* If the source address is 0, and the source address space
1745 cannot have a valid object at 0, fold to dest type null. */
1756 {
1757 /* Can't call fold_negate_const directly here as that doesn't
1758 handle all cases and we might not be able to negate some
1759 constants. */
1764 }
1774 {
1778 }
1786 /* Perform BIT_NOT_EXPR on each element individually. */
1788 {
1789 tree elem;
1791 /* This can cope with stepped encodings because ~x == -1 - x. */
1792 tree_vector_builder elements;
1796 {
1802 }
1805 }
1829 {
1852 else
1857 {
1863 }
1866 }
1875 }
1878 }
1880 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1881 indicates which particular sizetype to create. */
1883 tree
1885 {
1887 }
1888 \f
1889 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1890 is a tree code. The type of the result is taken from the operands.
1891 Both must be equivalent integer types, ala int_binop_types_match_p.
1892 If the operands are constant, so is the result. */
1894 tree
1896 {
1905 /* Handle the special case of two poly_int constants faster. */
1907 {
1908 /* And some specific cases even faster than that. */
1910 {
1917 }
1919 {
1923 }
1925 {
1929 }
1931 /* Handle general case of two integer constants. For sizetype
1932 constant calculations we always want to know about overflow,
1933 even in the unsigned case. */
1937 }
1940 }
1942 /* Given two values, either both of sizetype or both of bitsizetype,
1943 compute the difference between the two values. Return the value
1944 in signed type corresponding to the type of the operands. */
1946 tree
1948 {
1950 tree ctype;
1955 /* If the type is already signed, just do the simple thing. */
1963 else
1966 /* If either operand is not a constant, do the conversions to the signed
1967 type and subtract. The hardware will do the right thing with any
1968 overflow in the subtraction. */
1974 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1975 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1976 overflow) and negate (which can't either). Special-case a result
1977 of zero while we're here. */
1983 else
1987 MINUS_EXPR,
1989 }
1990 \f
1991 /* A subroutine of fold_convert_const handling conversions of an
1992 INTEGER_CST to another integer type. */
1994 static tree
1996 {
1997 /* Given an integer constant, make new constant with new type,
1998 appropriately sign-extended or truncated. Use widest_int
1999 so that any extension is done according ARG1's type. */
2003 }
2005 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2006 to an integer type. */
2008 static tree
2010 {
2012 tree t;
2014 /* The following code implements the floating point to integer
2015 conversion rules required by the Java Language Specification,
2016 that IEEE NaNs are mapped to zero and values that overflow
2017 the target precision saturate, i.e. values greater than
2018 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2019 are mapped to INT_MIN. These semantics are allowed by the
2020 C and C++ standards that simply state that the behavior of
2021 FP-to-integer conversion is unspecified upon overflow. */
2023 wide_int val;
2024 REAL_VALUE_TYPE r;
2028 {
2035 }
2037 /* If R is NaN, return zero and show we have an overflow. */
2039 {
2042 }
2044 /* See if R is less than the lower bound or greater than the
2045 upper bound. */
2048 {
2052 {
2055 }
2056 }
2059 {
2062 {
2065 {
2068 }
2069 }
2070 }
2077 }
2079 /* A subroutine of fold_convert_const handling conversions of a
2080 FIXED_CST to an integer type. */
2082 static tree
2084 {
2085 tree t;
2087 scalar_mode mode;
2089 /* Right shift FIXED_CST to temp by fbit. */
2093 {
2095 HOST_BITS_PER_DOUBLE_INT,
2098 /* Left shift temp to temp_trunc by fbit. */
2100 HOST_BITS_PER_DOUBLE_INT,
2102 }
2103 else
2104 {
2107 }
2109 /* If FIXED_CST is negative, we need to round the value toward 0.
2110 By checking if the fractional bits are not zero to add 1 to temp. */
2116 /* Given a fixed-point constant, make new constant with new type,
2117 appropriately sign-extended or truncated. */
2125 }
2127 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2128 to another floating point type. */
2130 static tree
2132 {
2133 REAL_VALUE_TYPE value;
2134 tree t;
2136 /* Don't perform the operation if flag_signaling_nans is on
2137 and the operand is a signaling NaN. */
2142 /* With flag_rounding_math we should respect the current rounding mode
2143 unless the conversion is exact. */
2151 /* If converting an infinity or NAN to a representation that doesn't
2152 have one, set the overflow bit so that we can produce some kind of
2153 error message at the appropriate point if necessary. It's not the
2154 most user-friendly message, but it's better than nothing. */
2161 /* Regular overflow, conversion produced an infinity in a mode that
2162 can't represent them. */
2167 else
2170 }
2172 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2173 to a floating point type. */
2175 static tree
2177 {
2178 REAL_VALUE_TYPE value;
2179 tree t;
2187 }
2189 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2190 to another fixed-point type. */
2192 static tree
2194 {
2195 FIXED_VALUE_TYPE value;
2196 tree t;
2203 /* Propagate overflow flags. */
2207 }
2209 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2210 to a fixed-point type. */
2212 static tree
2214 {
2215 FIXED_VALUE_TYPE value;
2216 tree t;
2218 double_int di;
2225 else
2233 /* Propagate overflow flags. */
2237 }
2239 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2240 to a fixed-point type. */
2242 static tree
2244 {
2245 FIXED_VALUE_TYPE value;
2246 tree t;
2254 /* Propagate overflow flags. */
2258 }
2260 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2261 type TYPE. If no simplification can be done return NULL_TREE. */
2263 static tree
2265 {
2270 /* We can't widen types, since the runtime value could overflow the
2271 original type before being extended to the new type. */
2282 {
2289 }
2291 {
2293 {
2295 /* Avoid the folding if flag_rounding_math is on and the
2296 conversion is not exact. */
2298 {
2304 }
2306 }
2311 }
2313 {
2320 }
2322 {
2325 {
2328 /* We can't handle steps directly when extending, since the
2329 values need to wrap at the original precision first. */
2330 bool step_ok_p
2334 tree_vector_builder v;
2339 {
2345 }
2347 }
2348 }
2350 }
2352 /* Construct a vector of zero elements of vector type TYPE. */
2354 static tree
2356 {
2357 tree t;
2361 }
2363 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2365 bool
2367 {
2382 {
2404 }
2405 }
2407 /* Convert expression ARG to type TYPE. Used by the middle-end for
2408 simple conversions in preference to calling the front-end's convert. */
2410 tree
2412 {
2414 tree tem;
2425 {
2428 /* Handle conversions between pointers to different address spaces. */
2433 /* fall through */
2438 {
2442 }
2456 {
2460 }
2462 {
2466 }
2468 {
2472 }
2475 {
2493 }
2498 {
2502 }
2505 {
2519 }
2523 {
2532 integer_zero_node));
2534 {
2538 {
2544 }
2552 }
2556 }
2574 }
2575 fold_convert_exit:
2578 }
2579 \f
2580 /* Return false if expr can be assumed not to be an lvalue, true
2581 otherwise. */
2583 static bool
2585 {
2586 /* We only need to wrap lvalue tree codes. */
2588 {
2620 /* Assume the worst for front-end tree codes. */
2624 }
2627 }
2629 /* Return an expr equal to X but certainly not valid as an lvalue. */
2631 tree
2633 {
2634 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2635 us. */
2642 }
2643 \f
2644 /* Given a tree comparison code, return the code that is the logical inverse.
2645 It is generally not safe to do this for floating-point comparisons, except
2646 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2647 ERROR_MARK in this case. */
2649 enum tree_code
2651 {
2657 {
2688 }
2689 }
2691 /* Similar, but return the comparison that results if the operands are
2692 swapped. This is safe for floating-point. */
2694 enum tree_code
2696 {
2698 {
2724 }
2725 }
2728 /* Convert a comparison tree code from an enum tree_code representation
2729 into a compcode bit-based encoding. This function is the inverse of
2730 compcode_to_comparison. */
2732 static enum comparison_code
2734 {
2736 {
2767 }
2768 }
2770 /* Convert a compcode bit-based encoding of a comparison operator back
2771 to GCC's enum tree_code representation. This function is the
2772 inverse of comparison_to_compcode. */
2774 static enum tree_code
2776 {
2778 {
2809 }
2810 }
2812 /* Return true if COND1 tests the opposite condition of COND2. */
2814 bool
2816 {
2819 && (invert_tree_comparison
2826 }
2828 /* Return a tree for the comparison which is the combination of
2829 doing the AND or OR (depending on CODE) of the two operations LCODE
2830 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2831 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2832 if this makes the transformation invalid. */
2834 tree
2839 {
2846 {
2857 }
2860 {
2861 /* Eliminate unordered comparisons, as well as LTGT and ORD
2862 which are not used unless the mode has NaNs. */
2868 }
2870 {
2871 /* Check that the original operation and the optimized ones will trap
2872 under the same condition. */
2883 /* In a short-circuited boolean expression the LHS might be
2884 such that the RHS, if evaluated, will never trap. For
2885 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2886 if neither x nor y is NaN. (This is a mixed blessing: for
2887 example, the expression above will never trap, hence
2888 optimizing it to x < y would be invalid). */
2893 /* If the comparison was short-circuited, and only the RHS
2894 trapped, we may now generate a spurious trap. */
2899 /* If we changed the conditions that cause a trap, we lose. */
2902 }
2908 else
2909 {
2914 }
2915 }
2916 \f
2917 /* Return nonzero if two operands (typically of the same tree node)
2918 are necessarily equal. FLAGS modifies behavior as follows:
2920 If OEP_ONLY_CONST is set, only return nonzero for constants.
2921 This function tests whether the operands are indistinguishable;
2922 it does not test whether they are equal using C's == operation.
2923 The distinction is important for IEEE floating point, because
2924 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2925 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2927 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2928 even though it may hold multiple values during a function.
2929 This is because a GCC tree node guarantees that nothing else is
2930 executed between the evaluation of its "operands" (which may often
2931 be evaluated in arbitrary order). Hence if the operands themselves
2932 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2933 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2934 unset means assuming isochronic (or instantaneous) tree equivalence.
2935 Unless comparing arbitrary expression trees, such as from different
2936 statements, this flag can usually be left unset.
2938 If OEP_PURE_SAME is set, then pure functions with identical arguments
2939 are considered the same. It is used when the caller has other ways
2940 to ensure that global memory is unchanged in between.
2942 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2943 not values of expressions.
2945 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2946 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2948 If OEP_BITWISE is set, then require the values to be bitwise identical
2949 rather than simply numerically equal. Do not take advantage of things
2950 like math-related flags or undefined behavior; only return true for
2951 values that are provably bitwise identical in all circumstances.
2953 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2954 any operand with side effect. This is unnecesarily conservative in the
2955 case we know that arg0 and arg1 are in disjoint code paths (such as in
2956 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2957 addresses with TREE_CONSTANT flag set so we know that &var == &var
2958 even if var is volatile. */
2960 bool
2963 {
2971 /* If either is ERROR_MARK, they aren't equal. */
2977 /* Similar, if either does not have a type (like a template id),
2978 they aren't equal. */
2982 /* Bitwise identity makes no sense if the values have different layouts. */
2987 /* We cannot consider pointers to different address space equal. */
2994 /* Check equality of integer constants before bailing out due to
2995 precision differences. */
2997 {
2998 /* Address of INTEGER_CST is not defined; check that we did not forget
2999 to drop the OEP_ADDRESS_OF flags. */
3002 }
3005 {
3006 /* If both types don't have the same signedness, then we can't consider
3007 them equal. We must check this before the STRIP_NOPS calls
3008 because they may change the signedness of the arguments. As pointers
3009 strictly don't have a signedness, require either two pointers or
3010 two non-pointers as well. */
3016 /* If both types don't have the same precision, then it is not safe
3017 to strip NOPs. */
3024 }
3025 #if 0
3026 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
3027 sanity check once the issue is solved. */
3028 else
3029 /* Addresses of conversions and SSA_NAMEs (and many other things)
3030 are not defined. Check that we did not forget to drop the
3031 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3034 #endif
3036 /* In case both args are comparisons but with different comparison
3037 code, try to swap the comparison operands of one arg to produce
3038 a match and compare that variant. */
3042 {
3050 }
3053 {
3054 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3056 ;
3058 {
3059 /* If we are interested in comparing addresses ignore
3060 MEM_REF wrappings of the base that can appear just for
3061 TBAA reasons. */
3075 }
3076 else
3078 }
3080 /* When not checking adddresses, this is needed for conversions and for
3081 COMPONENT_REF. Might as well play it safe and always test this. */
3088 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3089 We don't care about side effects in that case because the SAVE_EXPR
3090 takes care of that for us. In all other cases, two expressions are
3091 equal if they have no side effects. If we have two identical
3092 expressions with side effects that should be treated the same due
3093 to the only side effects being identical SAVE_EXPR's, that will
3094 be detected in the recursive calls below.
3095 If we are taking an invariant address of two identical objects
3096 they are necessarily equal as well. */
3103 /* Next handle constant cases, those for which we can return 1 even
3104 if ONLY_CONST is set. */
3107 {
3120 {
3121 /* If we do not distinguish between signed and unsigned zero,
3122 consider them equal. */
3125 }
3129 {
3144 }
3148 flags)
3150 flags));
3161 flags | OEP_ADDRESS_OF
3164 /* In GIMPLE empty constructors are allowed in initializers of
3165 aggregates. */
3169 }
3171 /* Don't handle more cases for OEP_BITWISE, since we can't guarantee that
3172 two instances of undefined behavior will give identical results. */
3176 /* Define macros to test an operand from arg0 and arg1 for equality and a
3177 variant that allows null and views null as being different from any
3178 non-null value. In the latter case, if either is null, the both
3179 must be; otherwise, do the normal comparison. */
3180 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3181 TREE_OPERAND (arg1, N), flags)
3183 #define OP_SAME_WITH_NULL(N) \
3184 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3185 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3188 {
3190 /* Two conversions are equal only if signedness and modes match. */
3192 {
3193 CASE_CONVERT:
3201 }
3211 /* For commutative ops, allow the other order. */
3219 /* If either of the pointer (or reference) expressions we are
3220 dereferencing contain a side effect, these cannot be equal,
3221 but their addresses can be. */
3228 {
3231 {
3235 /* Verify that the access types are compatible. */
3239 }
3244 /* Require the same offset. */
3250 /* Fallthru. */
3258 {
3259 /* Require equal access sizes */
3265 flags)))
3267 /* Verify that access happens in similar types. */
3270 /* Verify that accesses are TBAA compatible. */
3279 /* Verify that alignment is compatible. */
3283 }
3286 /* TARGET_MEM_REF require equal extra operands. */
3297 /* Compare the array index by value if it is constant first as we
3298 may have different types but same value here. */
3304 /* Compare low bound and element size as with OEP_ADDRESS_OF
3305 we have to account for the offset of the ref. */
3310 array_ref_low_bound
3314 array_ref_element_size
3316 flags))));
3319 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3320 may be NULL when we're called to compare MEM_EXPRs. */
3323 {
3326 /* Most of time we only need to compare FIELD_DECLs for equality.
3327 However when determining address look into actual offsets.
3328 These may match for unions and unshared record types. */
3331 {
3334 {
3345 flags))
3347 }
3348 else
3350 }
3351 }
3362 }
3366 {
3368 /* Be sure we pass right ADDRESS_OF flag. */
3385 /* The multiplcation operands are commutative. */
3386 /* FALLTHRU */
3394 /* Otherwise take into account this is a commutative operation. */
3407 /* BIT_INSERT_EXPR has an implict operand as the type precision
3408 of op1. Need to check to make sure they are the same. */
3414 /* FALLTHRU */
3439 /* Virtual table reference. */
3451 {
3456 }
3461 }
3465 {
3469 /* If not both CALL_EXPRs are either internal or normal function
3470 functions, then they are not equal. */
3473 {
3474 /* If the CALL_EXPRs call different internal functions, then they
3475 are not equal. */
3478 }
3479 else
3480 {
3481 /* If the CALL_EXPRs call different functions, then they are not
3482 equal. */
3484 flags))
3486 }
3488 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3489 {
3493 else
3497 }
3499 /* Now see if all the arguments are the same. */
3500 {
3511 /* If we get here and both argument lists are exhausted
3512 then the CALL_EXPRs are equal. */
3514 }
3517 }
3520 /* Consider __builtin_sqrt equal to sqrt. */
3530 {
3531 /* Consider decls with the same name equal. The caller needs
3532 to make sure they refer to the same entity (such as a function
3533 formal parameter). */
3539 }
3544 {
3548 /* In GIMPLE constructors are used only to build vectors from
3549 elements. Individual elements in the constructor must be
3550 indexed in increasing order and form an initial sequence.
3552 We make no effort to compare constructors in generic.
3553 (see sem_variable::equals in ipa-icf which can do so for
3554 constants). */
3559 /* Be sure that vectors constructed have the same representation.
3560 We only tested element precision and modes to match.
3561 Vectors may be BLKmode and thus also check that the number of
3562 parts match. */
3575 {
3580 /* In GIMPLE the indexes can be either NULL or matching i.
3581 Double check this so we won't get false
3582 positives for GENERIC. */
3590 }
3592 }
3595 {
3596 /* Compare the STATEMENT_LISTs. */
3602 {
3603 /* The lists don't have the same number of statements. */
3609 flags & (OEP_LEXICOGRAPHIC
3612 }
3613 }
3618 {
3629 }
3633 }
3635 #undef OP_SAME
3636 #undef OP_SAME_WITH_NULL
3637 }
3639 /* Generate a hash value for an expression. This can be used iteratively
3640 by passing a previous result as the HSTATE argument. */
3642 void
3645 {
3651 {
3654 }
3664 {
3665 /* Alas, constants aren't shared, so we can't rely on pointer
3666 identity. */
3676 {
3680 else
3684 }
3686 {
3690 }
3700 {
3707 }
3709 /* We can just compare by pointer. */
3713 /* The node itself doesn't matter. */
3717 /* Ignore. */
3720 /* A list of expressions, for a CALL_EXPR or as the elements of a
3721 VECTOR_CST. */
3726 {
3732 {
3733 /* In GIMPLE the indexes can be either NULL or matching i. */
3738 }
3740 }
3742 {
3743 tree_stmt_iterator i;
3748 }
3757 /* When referring to a built-in FUNCTION_DECL, use the __builtin__ form.
3758 Otherwise nodes that compare equal according to operand_equal_p might
3759 get different hash codes. However, don't do this for machine specific
3760 or front end builtins, since the function code is overloaded in those
3761 cases. */
3764 {
3767 }
3768 /* FALL THROUGH */
3771 {
3775 }
3779 {
3780 /* DECL's have a unique ID */
3782 }
3784 {
3785 /* For comparisons that can be swapped, use the lower
3786 tree code. */
3793 }
3795 {
3796 /* NOP_EXPR and CONVERT_EXPR are considered equal by
3797 operand_equal_p. */
3801 /* Don't hash the type, that can lead to having nodes which
3802 compare equal according to operand_equal_p, but which
3803 have different hash codes. Make sure to include signedness
3804 in the hash computation. */
3807 }
3808 /* For OEP_ADDRESS_OF, hash MEM_EXPR[&decl, 0] the same as decl. */
3816 /* Don't ICE on FE specific trees, or their arguments etc.
3817 during operand_equal_p hash verification. */
3820 else
3821 {
3827 {
3843 {
3848 else
3849 {
3855 }
3857 }
3871 {
3872 /* The multiplication operands are commutative. */
3879 }
3887 /* For TARGET_EXPR, just hash on the TARGET_EXPR_SLOT.
3888 Usually different TARGET_EXPRs just should use
3889 different temporaries in their slots. */
3894 /* Virtual table reference. */
3902 {
3904 /* We compute mangled names only when free_lang_data is run.
3905 In that case we can hash precisely. */
3908 hstate.add_object
3909 (IDENTIFIER_HASH_VALUE
3911 }
3915 }
3917 /* Don't hash the type, that can lead to having nodes which
3918 compare equal according to operand_equal_p, but which
3919 have different hash codes. */
3921 {
3922 /* Make sure to include signness in the hash computation. */
3925 }
3928 {
3929 /* It's a commutative expression. We want to hash it the same
3930 however it appears. We do this by first hashing both operands
3931 and then rehashing based on the order of their independent
3932 hashes. */
3937 }
3938 else
3942 }
3944 }
3945 }
3947 bool
3950 {
3951 /* When checking and unless comparing DECL names, verify that if
3952 the outermost operand_equal_p call returns non-zero then ARG0
3953 and ARG1 have the same hash value. */
3955 {
3957 {
3959 {
3966 }
3968 }
3969 else
3973 }
3976 }
3981 /* Conveinece wrapper around operand_compare class because usually we do
3982 not need to play with the valueizer. */
3984 bool
3986 {
3988 }
3990 namespace inchash
3991 {
3993 /* Generate a hash value for an expression. This can be used iteratively
3994 by passing a previous result as the HSTATE argument.
3996 This function is intended to produce the same hash for expressions which
3997 would compare equal using operand_equal_p. */
3998 void
4000 {
4002 }
4004 }
4005 \f
4006 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
4007 with a different signedness or a narrower precision. */
4009 static bool
4011 {
4019 /* Discard any conversions that don't change the modes of ARG0 and ARG1
4020 and see if the inner values are the same. This removes any
4021 signedness comparison, which doesn't matter here. */
4029 /* Discard a single widening conversion from ARG1 and see if the inner
4030 value is the same as ARG0. */
4039 }
4040 \f
4041 /* See if ARG is an expression that is either a comparison or is performing
4042 arithmetic on comparisons. The comparisons must only be comparing
4043 two different values, which will be stored in *CVAL1 and *CVAL2; if
4044 they are nonzero it means that some operands have already been found.
4045 No variables may be used anywhere else in the expression except in the
4046 comparisons.
4048 If this is true, return 1. Otherwise, return zero. */
4050 static bool
4052 {
4056 /* We can handle some of the tcc_expression cases here. */
4065 {
4084 /* First see if we can handle the first operand, then the second. For
4085 the second operand, we know *CVAL1 can't be zero. It must be that
4086 one side of the comparison is each of the values; test for the
4087 case where this isn't true by failing if the two operands
4088 are the same. */
4097 ;
4101 ;
4102 else
4106 ;
4110 ;
4111 else
4118 }
4119 }
4120 \f
4121 /* ARG is a tree that is known to contain just arithmetic operations and
4122 comparisons. Evaluate the operations in the tree substituting NEW0 for
4123 any occurrence of OLD0 as an operand of a comparison and likewise for
4124 NEW1 and OLD1. */
4126 static tree
4129 {
4134 /* We can handle some of the tcc_expression cases here. */
4142 {
4157 {
4176 }
4177 /* Fall through - ??? */
4180 {
4184 /* We need to check both for exact equality and tree equality. The
4185 former will be true if the operand has a side-effect. In that
4186 case, we know the operand occurred exactly once. */
4199 }
4203 }
4204 }
4205 \f
4206 /* Return a tree for the case when the result of an expression is RESULT
4207 converted to TYPE and OMITTED was previously an operand of the expression
4208 but is now not needed (e.g., we folded OMITTED * 0).
4210 If OMITTED has side effects, we must evaluate it. Otherwise, just do
4211 the conversion of RESULT to TYPE. */
4213 tree
4215 {
4218 /* If the resulting operand is an empty statement, just return the omitted
4219 statement casted to void. */
4229 }
4231 /* Return a tree for the case when the result of an expression is RESULT
4232 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
4233 of the expression but are now not needed.
4235 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
4236 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
4237 evaluated before OMITTED2. Otherwise, if neither has side effects,
4238 just do the conversion of RESULT to TYPE. */
4240 tree
4243 {
4252 }
4254 \f
4255 /* Return a simplified tree node for the truth-negation of ARG. This
4256 never alters ARG itself. We assume that ARG is an operation that
4257 returns a truth value (0 or 1).
4259 FIXME: one would think we would fold the result, but it causes
4260 problems with the dominator optimizer. */
4262 static tree
4264 {
4269 /* If this is a comparison, we can simply invert it, except for
4270 floating-point non-equality comparisons, in which case we just
4271 enclose a TRUTH_NOT_EXPR around what we have. */
4274 {
4277 && flag_trapping_math
4290 }
4293 {
4312 /* Here we can invert either operand. We invert the first operand
4313 unless the second operand is a TRUTH_NOT_EXPR in which case our
4314 result is the XOR of the first operand with the inside of the
4315 negation of the second operand. */
4320 else
4343 {
4350 /* A COND_EXPR may have a throw as one operand, which
4351 then has void type. Just leave void operands
4352 as they are. */
4358 }
4370 CASE_CONVERT:
4374 /* fall through */
4396 }
4397 }
4399 /* Fold the truth-negation of ARG. This never alters ARG itself. We
4400 assume that ARG is an operation that returns a truth value (0 or 1
4401 for scalars, 0 or -1 for vectors). Return the folded expression if
4402 folding is successful. Otherwise, return NULL_TREE. */
4404 static tree
4406 {
4409 ? BIT_NOT_EXPR
4412 }
4414 /* Return a simplified tree node for the truth-negation of ARG. This
4415 never alters ARG itself. We assume that ARG is an operation that
4416 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
4418 tree
4420 {
4426 ? BIT_NOT_EXPR
4429 }
4430 \f
4431 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4432 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
4433 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
4434 is the original memory reference used to preserve the alias set of
4435 the access. */
4437 static tree
4441 {
4444 /* Attempt not to lose the access path if possible. */
4446 {
4448 machine_mode nmode;
4450 tree noffset;
4458 && !reversep
4459 && !nreversep
4461 {
4464 }
4465 }
4474 {
4481 }
4496 }
4498 /* Optimize a bit-field compare.
4500 There are two cases: First is a compare against a constant and the
4501 second is a comparison of two items where the fields are at the same
4502 bit position relative to the start of a chunk (byte, halfword, word)
4503 large enough to contain it. In these cases we can avoid the shift
4504 implicit in bitfield extractions.
4506 For constants, we emit a compare of the shifted constant with the
4507 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4508 compared. For two fields at the same position, we do the ANDs with the
4509 similar mask and compare the result of the ANDs.
4511 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4512 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4513 are the left and right operands of the comparison, respectively.
4515 If the optimization described above can be done, we return the resulting
4516 tree. Otherwise we return zero. */
4518 static tree
4521 {
4525 tree unsigned_type;
4528 scalar_int_mode nmode;
4533 tree mask;
4534 tree offset;
4536 /* Get all the information about the extractions being done. If the bit size
4537 is the same as the size of the underlying object, we aren't doing an
4538 extraction at all and so can do nothing. We also don't want to
4539 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4540 then will no longer be able to replace it. */
4555 else
4556 {
4557 /* If this is not a constant, we can only do something if bit positions,
4558 sizes, signedness and storage order are the same. */
4559 rinner
4572 }
4574 /* Honor the C++ memory model and mimic what RTL expansion does. */
4578 {
4582 }
4584 /* See if we can find a mode to refer to this field. We should be able to,
4585 but fail if we can't. */
4593 /* Set signed and unsigned types of the precision of this mode for the
4594 shifts below. */
4597 /* Compute the bit position and size for the new reference and our offset
4598 within it. If the new reference is the same size as the original, we
4599 won't optimize anything, so return zero. */
4609 /* Make the mask to be used against the extracted field. */
4616 {
4620 /* If not comparing with constant, just rework the comparison
4621 and return. */
4629 }
4631 /* Otherwise, we are handling the constant case. See if the constant is too
4632 big for the field. Warn and return a tree for 0 (false) if so. We do
4633 this not only for its own sake, but to avoid having to test for this
4634 error case below. If we didn't, we might generate wrong code.
4636 For unsigned fields, the constant shifted right by the field length should
4637 be all zero. For signed fields, the high-order bits should agree with
4638 the sign bit. */
4641 {
4643 {
4647 }
4648 }
4649 else
4650 {
4653 {
4657 }
4658 }
4663 /* Single-bit compares should always be against zero. */
4665 {
4668 }
4670 /* Make a new bitfield reference, shift the constant over the
4671 appropriate number of bits and mask it with the computed mask
4672 (in case this was a signed field). If we changed it, make a new one. */
4680 mask);
4685 }
4686 \f
4687 /* Subroutine for fold_truth_andor_1: decode a field reference.
4689 If EXP is a comparison reference, we return the innermost reference.
4691 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4692 set to the starting bit number.
4694 If the innermost field can be completely contained in a mode-sized
4695 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4697 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4698 otherwise it is not changed.
4700 *PUNSIGNEDP is set to the signedness of the field.
4702 *PREVERSEP is set to the storage order of the field.
4704 *PMASK is set to the mask used. This is either contained in a
4705 BIT_AND_EXPR or derived from the width of the field.
4707 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4709 Return 0 if this is not a component reference or is one that we can't
4710 do anything with. */
4712 static tree
4717 {
4722 tree unsigned_type;
4725 /* All the optimizations using this function assume integer fields.
4726 There are problems with FP fields since the type_for_size call
4727 below can fail for, e.g., XFmode. */
4731 /* We are interested in the bare arrangement of bits, so strip everything
4732 that doesn't affect the machine mode. However, record the type of the
4733 outermost expression if it may matter below. */
4740 {
4746 }
4757 /* Reject out-of-bound accesses (PR79731). */
4769 /* If the number of bits in the reference is the same as the bitsize of
4770 the outer type, then the outer type gives the signedness. Otherwise
4771 (in case of a small bitfield) the signedness is unchanged. */
4775 /* Compute the mask to access the bitfield. */
4783 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4791 }
4793 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4794 bit positions and MASK is SIGNED. */
4796 static bool
4798 {
4802 /* If this function returns true when the type of the mask is
4803 UNSIGNED, then there will be errors. In particular see
4804 gcc.c-torture/execute/990326-1.c. There does not appear to be
4805 any documentation paper trail as to why this is so. But the pre
4806 wide-int worked with that restriction and it has been preserved
4807 here. */
4812 }
4814 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4815 represents the sign bit of EXP's type. If EXP represents a sign
4816 or zero extension, also test VAL against the unextended type.
4817 The return value is the (sub)expression whose sign bit is VAL,
4818 or NULL_TREE otherwise. */
4820 tree
4822 {
4824 tree t;
4826 /* Tree EXP must have an integral type. */
4831 /* Tree VAL must be an integer constant. */
4840 /* Handle extension from a narrower type. */
4846 }
4848 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4849 to be evaluated unconditionally. */
4851 static bool
4853 {
4854 /* Strip any conversions that don't change the machine mode. */
4863 /* Don't regard global variables as simple. They may be
4864 allocated in ways unknown to the compiler (shared memory,
4865 #pragma weak, etc). */
4868 /* Weakrefs are not safe to be read, since they can be NULL.
4869 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4870 have DECL_WEAK flag set. */
4872 /* Loading a static variable is unduly expensive, but global
4873 registers aren't expensive. */
4875 }
4877 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4878 to be evaluated unconditionally.
4879 I addition to simple_operand_p, we assume that comparisons, conversions,
4880 and logic-not operations are simple, if their operands are simple, too. */
4882 static bool
4884 {
4903 }
4905 \f
4906 /* The following functions are subroutines to fold_range_test and allow it to
4907 try to change a logical combination of comparisons into a range test.
4909 For example, both
4910 X == 2 || X == 3 || X == 4 || X == 5
4911 and
4912 X >= 2 && X <= 5
4913 are converted to
4914 (unsigned) (X - 2) <= 3
4916 We describe each set of comparisons as being either inside or outside
4917 a range, using a variable named like IN_P, and then describe the
4918 range with a lower and upper bound. If one of the bounds is omitted,
4919 it represents either the highest or lowest value of the type.
4921 In the comments below, we represent a range by two numbers in brackets
4922 preceded by a "+" to designate being inside that range, or a "-" to
4923 designate being outside that range, so the condition can be inverted by
4924 flipping the prefix. An omitted bound is represented by a "-". For
4925 example, "- [-, 10]" means being outside the range starting at the lowest
4926 possible value and ending at 10, in other words, being greater than 10.
4927 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4928 always false.
4930 We set up things so that the missing bounds are handled in a consistent
4931 manner so neither a missing bound nor "true" and "false" need to be
4932 handled using a special case. */
4934 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4935 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4936 and UPPER1_P are nonzero if the respective argument is an upper bound
4937 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4938 must be specified for a comparison. ARG1 will be converted to ARG0's
4939 type if both are specified. */
4941 static tree
4944 {
4945 tree tem;
4949 /* If neither arg represents infinity, do the normal operation.
4950 Else, if not a comparison, return infinity. Else handle the special
4951 comparison rules. Note that most of the cases below won't occur, but
4952 are handled for consistency. */
4955 {
4960 }
4965 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4966 for neither. In real maths, we cannot assume open ended ranges are
4967 the same. But, this is computer arithmetic, where numbers are finite.
4968 We can therefore make the transformation of any unbounded range with
4969 the value Z, Z being greater than any representable number. This permits
4970 us to treat unbounded ranges as equal. */
4974 {
4995 }
4998 }
4999 \f
5000 /* Helper routine for make_range. Perform one step for it, return
5001 new expression if the loop should continue or NULL_TREE if it should
5002 stop. */
5004 tree
5008 {
5014 {
5016 /* We can only do something if the range is testing for zero. */
5025 /* We can only do something if the range is testing for zero
5026 and if the second operand is an integer constant. Note that
5027 saying something is "in" the range we make is done by
5028 complementing IN_P since it will set in the initial case of
5029 being not equal to zero; "out" is leaving it alone. */
5036 {
5057 }
5059 /* If this is an unsigned comparison, we also know that EXP is
5060 greater than or equal to zero. We base the range tests we make
5061 on that fact, so we record it here so we can parse existing
5062 range tests. We test arg0_type since often the return type
5063 of, e.g. EQ_EXPR, is boolean. */
5065 {
5069 NULL_TREE))
5074 /* If the high bound is missing, but we have a nonzero low
5075 bound, reverse the range so it goes from zero to the low bound
5076 minus 1. */
5078 {
5083 }
5084 }
5092 /* If flag_wrapv and ARG0_TYPE is signed, make sure
5093 low and high are non-NULL, then normalize will DTRT. */
5096 {
5101 }
5103 /* (-x) IN [a,b] -> x in [-b, -a] */
5115 /* ~ X -> -X - 1 */
5124 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
5125 move a constant to the other side. */
5130 /* If EXP is signed, any overflow in the computation is undefined,
5131 so we don't worry about it so long as our computations on
5132 the bounds don't overflow. For unsigned, overflow is defined
5133 and this is exactly the right thing. */
5145 normalize:
5146 /* Check for an unsigned range which has wrapped around the maximum
5147 value thus making n_high < n_low, and normalize it. */
5149 {
5155 /* If the range is of the form +/- [ x+1, x ], we won't
5156 be able to normalize it. But then, it represents the
5157 whole range or the empty set, so make it
5158 +/- [ -, - ]. */
5162 else
5164 }
5165 else
5173 CASE_CONVERT:
5191 /* If we're converting arg0 from an unsigned type, to exp,
5192 a signed type, we will be doing the comparison as unsigned.
5193 The tests above have already verified that LOW and HIGH
5194 are both positive.
5196 So we have to ensure that we will handle large unsigned
5197 values the same way that the current signed bounds treat
5198 negative values. */
5201 {
5202 tree high_positive;
5203 tree equiv_type;
5204 /* For fixed-point modes, we need to pass the saturating flag
5205 as the 2nd parameter. */
5207 equiv_type
5210 else
5211 equiv_type
5214 /* A range without an upper bound is, naturally, unbounded.
5215 Since convert would have cropped a very large value, use
5216 the max value for the destination type. */
5217 high_positive
5224 high_positive),
5227 /* If the low bound is specified, "and" the range with the
5228 range for which the original unsigned value will be
5229 positive. */
5231 {
5234 integer_zero_node),
5235 high_positive))
5239 }
5240 else
5241 {
5242 /* Otherwise, "or" the range with the range of the input
5243 that will be interpreted as negative. */
5246 integer_zero_node),
5247 high_positive))
5251 }
5252 }
5261 }
5262 }
5264 /* Given EXP, a logical expression, set the range it is testing into
5265 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
5266 actually being tested. *PLOW and *PHIGH will be made of the same
5267 type as the returned expression. If EXP is not a comparison, we
5268 will most likely not be returning a useful value and range. Set
5269 *STRICT_OVERFLOW_P to true if the return value is only valid
5270 because signed overflow is undefined; otherwise, do not change
5271 *STRICT_OVERFLOW_P. */
5273 tree
5276 {
5284 /* Start with simply saying "EXP != 0" and then look at the code of EXP
5285 and see if we can refine the range. Some of the cases below may not
5286 happen, but it doesn't seem worth worrying about this. We "continue"
5287 the outer loop when we've changed something; otherwise we "break"
5288 the switch, which will "break" the while. */
5294 {
5300 {
5308 }
5317 }
5319 /* If EXP is a constant, we can evaluate whether this is true or false. */
5321 {
5328 }
5332 }
5334 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
5335 a bitwise check i.e. when
5336 LOW == 0xXX...X00...0
5337 HIGH == 0xXX...X11...1
5338 Return corresponding mask in MASK and stem in VALUE. */
5340 static bool
5343 {
5366 }
5367 \f
5368 /* Helper routine for build_range_check and match.pd. Return the type to
5369 perform the check or NULL if it shouldn't be optimized. */
5371 tree
5373 {
5374 /* First make sure that arithmetics in this type is valid, then make sure
5375 that it wraps around. */
5380 {
5383 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5384 for the type in question, as we rely on this here. */
5394 else
5396 }
5400 }
5402 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
5403 type, TYPE, return an expression to test if EXP is in (or out of, depending
5404 on IN_P) the range. Return 0 if the test couldn't be created. */
5406 tree
5409 {
5412 /* Disable this optimization for function pointer expressions
5413 on targets that require function pointer canonicalization. */
5420 {
5426 }
5448 value);
5451 {
5453 {
5457 }
5459 }
5461 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5463 {
5467 {
5469 {
5472 etype
5474 else
5477 }
5480 }
5481 }
5483 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5484 This requires wrap-around arithmetics for the type of the expression. */
5501 }
5502 \f
5503 /* Return the predecessor of VAL in its type, handling the infinite case. */
5505 static tree
5507 {
5513 else
5516 }
5518 /* Return the successor of VAL in its type, handling the infinite case. */
5520 static tree
5522 {
5528 else
5531 }
5533 /* Given two ranges, see if we can merge them into one. Return 1 if we
5534 can, 0 if we can't. Set the output range into the specified parameters. */
5536 bool
5539 {
5543 tree tem;
5553 /* Make range 0 be the range that starts first, or ends last if they
5554 start at the same value. Swap them if it isn't. */
5557 || (lowequal
5560 {
5564 }
5566 /* If the second range is != high1 where high1 is the type maximum of
5567 the type, try first merging with < high1 range. */
5569 && high1
5576 {
5581 /* Similarly for the second range != low1 where low1 is the type minimum
5582 of the type, try first merging with > low1 range. */
5587 }
5589 /* Now flag two cases, whether the ranges are disjoint or whether the
5590 second range is totally subsumed in the first. Note that the tests
5591 below are simplified by the ones above. */
5597 /* We now have four cases, depending on whether we are including or
5598 excluding the two ranges. */
5600 {
5601 /* If they don't overlap, the result is false. If the second range
5602 is a subset it is the result. Otherwise, the range is from the start
5603 of the second to the end of the first. */
5608 else
5610 }
5613 {
5614 /* If they don't overlap, the result is the first range. If they are
5615 equal, the result is false. If the second range is a subset of the
5616 first, and the ranges begin at the same place, we go from just after
5617 the end of the second range to the end of the first. If the second
5618 range is not a subset of the first, or if it is a subset and both
5619 ranges end at the same place, the range starts at the start of the
5620 first range and ends just before the second range.
5621 Otherwise, we can't describe this as a single range. */
5627 {
5632 {
5633 /* We are in the weird situation where high0 > high1 but
5634 high1 has no successor. Punt. */
5636 }
5637 }
5639 {
5644 {
5645 /* low0 < low1 but low1 has no predecessor. Punt. */
5647 }
5648 }
5649 else
5651 }
5654 {
5655 /* If they don't overlap, the result is the second range. If the second
5656 is a subset of the first, the result is false. Otherwise,
5657 the range starts just after the first range and ends at the
5658 end of the second. */
5663 else
5664 {
5669 {
5670 /* high1 > high0 but high0 has no successor. Punt. */
5672 }
5673 }
5674 }
5676 else
5677 {
5678 /* The case where we are excluding both ranges. Here the complex case
5679 is if they don't overlap. In that case, the only time we have a
5680 range is if they are adjacent. If the second is a subset of the
5681 first, the result is the first. Otherwise, the range to exclude
5682 starts at the beginning of the first range and ends at the end of the
5683 second. */
5685 {
5690 else
5691 {
5692 /* Canonicalize - [min, x] into - [-, x]. */
5695 {
5698 GET_MODE_BITSIZE
5701 /* FALLTHROUGH */
5714 }
5716 /* Canonicalize - [x, max] into - [x, -]. */
5719 {
5722 GET_MODE_BITSIZE
5725 /* FALLTHROUGH */
5741 }
5743 /* The ranges might be also adjacent between the maximum and
5744 minimum values of the given type. For
5745 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5746 return + [x + 1, y - 1]. */
5748 {
5755 }
5756 else
5758 }
5759 }
5762 else
5764 }
5768 }
5769 \f
5771 /* Subroutine of fold, looking inside expressions of the form
5772 A op B ? A : C, where (ARG00, COMP_CODE, ARG01), ARG1 and ARG2
5773 are the three operands of the COND_EXPR. This function is
5774 being used also to optimize A op B ? C : A, by reversing the
5775 comparison first.
5777 Return a folded expression whose code is not a COND_EXPR
5778 anymore, or NULL_TREE if no folding opportunity is found. */
5780 static tree
5784 {
5786 tree tem;
5791 /* If we have A op 0 ? A : -A, consider applying the following
5792 transformations:
5794 A == 0? A : -A same as -A
5795 A != 0? A : -A same as A
5796 A >= 0? A : -A same as abs (A)
5797 A > 0? A : -A same as abs (A)
5798 A <= 0? A : -A same as -abs (A)
5799 A < 0? A : -A same as -abs (A)
5801 None of these transformations work for modes with signed
5802 zeros. If A is +/-0, the first two transformations will
5803 change the sign of the result (from +0 to -0, or vice
5804 versa). The last four will fix the sign of the result,
5805 even though the original expressions could be positive or
5806 negative, depending on the sign of A.
5808 Note that all these transformations are correct if A is
5809 NaN, since the two alternatives (A and -A) are also NaNs. */
5816 /* In the case that A is of the form X-Y, '-A' (arg2) may
5817 have already been folded to Y-X, check for that. */
5825 {
5837 /* Fall through. */
5848 /* FALLTHRU */
5855 {
5856 /* A <= 0 ? A : -A for A INT_MIN is valid, but -abs(INT_MIN)
5857 is not, invokes UB both in abs and in the negation of it.
5858 So, use ABSU_EXPR instead. */
5863 }
5864 else
5865 {
5868 }
5872 }
5874 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5875 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5876 both transformations are correct when A is NaN: A != 0
5877 is then true, and A == 0 is false. */
5881 {
5886 }
5888 /* Try some transformations of A op B ? A : B.
5890 A == B? A : B same as B
5891 A != B? A : B same as A
5892 A >= B? A : B same as max (A, B)
5893 A > B? A : B same as max (B, A)
5894 A <= B? A : B same as min (A, B)
5895 A < B? A : B same as min (B, A)
5897 As above, these transformations don't work in the presence
5898 of signed zeros. For example, if A and B are zeros of
5899 opposite sign, the first two transformations will change
5900 the sign of the result. In the last four, the original
5901 expressions give different results for (A=+0, B=-0) and
5902 (A=-0, B=+0), but the transformed expressions do not.
5904 The first two transformations are correct if either A or B
5905 is a NaN. In the first transformation, the condition will
5906 be false, and B will indeed be chosen. In the case of the
5907 second transformation, the condition A != B will be true,
5908 and A will be chosen.
5910 The conversions to max() and min() are not correct if B is
5911 a number and A is not. The conditions in the original
5912 expressions will be false, so all four give B. The min()
5913 and max() versions would give a NaN instead. */
5916 /* Avoid these transformations if the COND_EXPR may be used
5917 as an lvalue in the C++ front-end. PR c++/19199. */
5918 && (in_gimple_form
5924 {
5930 {
5939 /* In C++ a ?: expression can be an lvalue, so put the
5940 operand which will be used if they are equal first
5941 so that we can convert this back to the
5942 corresponding COND_EXPR. */
5944 {
5952 }
5959 {
5967 }
5980 }
5981 }
5984 }
5987 \f
5988 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5989 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5990 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5991 false) >= 2)
5992 #endif
5994 /* EXP is some logical combination of boolean tests. See if we can
5995 merge it into some range test. Return the new tree if so. */
5997 static tree
6000 {
6014 /* If op0 is known true or false and this is a short-circuiting
6015 operation we must not merge with op1 since that makes side-effects
6016 unconditional. So special-case this. */
6023 /* If this is an OR operation, invert both sides; we will invert
6024 again at the end. */
6028 /* If both expressions are the same, if we can merge the ranges, and we
6029 can build the range test, return it or it inverted. If one of the
6030 ranges is always true or always false, consider it to be the same
6031 expression as the other. */
6039 {
6043 }
6045 /* On machines where the branch cost is expensive, if this is a
6046 short-circuited branch and the underlying object on both sides
6047 is the same, make a non-short-circuit operation. */
6050 logical_op_non_short_circuit
6057 {
6058 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
6059 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
6060 which cases we can't do this. */
6068 {
6077 {
6080 WARN_STRICT_OVERFLOW_COMPARISON);
6084 }
6085 }
6086 }
6089 }
6090 \f
6091 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
6092 bit value. Arrange things so the extra bits will be set to zero if and
6093 only if C is signed-extended to its full width. If MASK is nonzero,
6094 it is an INTEGER_CST that should be AND'ed with the extra bits. */
6096 static tree
6098 {
6101 tree temp;
6106 /* We work by getting just the sign bit into the low-order bit, then
6107 into the high-order bit, then sign-extend. We then XOR that value
6108 with C. */
6112 /* We must use a signed type in order to get an arithmetic right shift.
6113 However, we must also avoid introducing accidental overflows, so that
6114 a subsequent call to integer_zerop will work. Hence we must
6115 do the type conversion here. At this point, the constant is either
6116 zero or one, and the conversion to a signed type can never overflow.
6117 We could get an overflow if this conversion is done anywhere else. */
6126 /* If necessary, convert the type back to match the type of C. */
6131 }
6132 \f
6133 /* For an expression that has the form
6134 (A && B) || ~B
6135 or
6136 (A || B) && ~B,
6137 we can drop one of the inner expressions and simplify to
6138 A || ~B
6139 or
6140 A && ~B
6141 LOC is the location of the resulting expression. OP is the inner
6142 logical operation; the left-hand side in the examples above, while CMPOP
6143 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
6144 removing a condition that guards another, as in
6145 (A != NULL && A->...) || A == NULL
6146 which we must not transform. If RHS_ONLY is true, only eliminate the
6147 right-most operand of the inner logical operation. */
6149 static tree
6152 {
6170 {
6173 {
6176 }
6177 }
6179 {
6182 {
6185 }
6186 }
6201 }
6203 /* Find ways of folding logical expressions of LHS and RHS:
6204 Try to merge two comparisons to the same innermost item.
6205 Look for range tests like "ch >= '0' && ch <= '9'".
6206 Look for combinations of simple terms on machines with expensive branches
6207 and evaluate the RHS unconditionally.
6209 For example, if we have p->a == 2 && p->b == 4 and we can make an
6210 object large enough to span both A and B, we can do this with a comparison
6211 against the object ANDed with the a mask.
6213 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
6214 operations to do this with one comparison.
6216 We check for both normal comparisons and the BIT_AND_EXPRs made this by
6217 function and the one above.
6219 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
6220 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
6222 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
6223 two operands.
6225 We return the simplified tree or 0 if no optimization is possible. */
6227 static tree
6230 {
6231 /* If this is the "or" of two comparisons, we can do something if
6232 the comparisons are NE_EXPR. If this is the "and", we can do something
6233 if the comparisons are EQ_EXPR. I.e.,
6234 (a->b == 2 && a->c == 4) can become (a->new == NEW).
6236 WANTED_CODE is this operation code. For single bit fields, we can
6237 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
6238 comparison for one-bit fields. */
6259 /* Start by getting the comparison codes. Fail if anything is volatile.
6260 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
6261 it were surrounded with a NE_EXPR. */
6270 {
6274 }
6277 {
6281 }
6292 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
6295 {
6298 {
6303 }
6306 {
6312 }
6313 }
6318 /* If the RHS can be evaluated unconditionally and its operands are
6319 simple, it wins to evaluate the RHS unconditionally on machines
6320 with expensive branches. In this case, this isn't a comparison
6321 that can be merged. */
6328 {
6329 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
6340 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
6350 }
6352 /* See if the comparisons can be merged. Then get all the parameters for
6353 each side. */
6378 /* It must be true that the inner operation on the lhs of each
6379 comparison must be the same if we are to be able to do anything.
6380 Then see if we have constants. If not, the same must be true for
6381 the rhs's. */
6390 {
6393 }
6398 else
6401 /* If either comparison code is not correct for our logical operation,
6402 fail. However, we can convert a one-bit comparison against zero into
6403 the opposite comparison against that bit being set in the field. */
6407 {
6409 {
6410 /* Make the left operand unsigned, since we are only interested
6411 in the value of one bit. Otherwise we are doing the wrong
6412 thing below. */
6415 }
6416 else
6418 }
6420 /* This is analogous to the code for l_const above. */
6422 {
6424 {
6427 }
6428 else
6430 }
6432 /* See if we can find a mode that contains both fields being compared on
6433 the left. If we can't, fail. Otherwise, update all constants and masks
6434 to be relative to a field of that size. */
6448 {
6451 }
6459 {
6466 {
6470 }
6471 }
6473 {
6480 {
6484 }
6485 }
6487 /* If the right sides are not constant, do the same for it. Also,
6488 disallow this optimization if a size, signedness or storage order
6489 mismatch occurs between the left and right sides. */
6491 {
6495 /* Make sure the two fields on the right
6496 correspond to the left without being swapped. */
6513 {
6516 }
6525 /* Make a mask that corresponds to both fields being compared.
6526 Do this for both items being compared. If the operands are the
6527 same size and the bits being compared are in the same position
6528 then we can do this by masking both and comparing the masked
6529 results. */
6536 {
6550 }
6552 /* There is still another way we can do something: If both pairs of
6553 fields being compared are adjacent, we may be able to make a wider
6554 field containing them both.
6556 Note that we still must mask the lhs/rhs expressions. Furthermore,
6557 the mask must be shifted to account for the shift done by
6558 make_bit_field_ref. */
6567 {
6568 tree type;
6584 /* Convert to the smaller type before masking out unwanted bits. */
6587 {
6589 {
6593 }
6595 {
6599 }
6600 }
6609 }
6612 }
6614 /* Handle the case of comparisons with constants. If there is something in
6615 common between the masks, those bits of the constants must be the same.
6616 If not, the condition is always false. Test for this to avoid generating
6617 incorrect code below. */
6622 {
6624 {
6627 }
6628 else
6629 {
6632 }
6633 }
6638 /* Construct the expression we will return. First get the component
6639 reference we will make. Unless the mask is all ones the width of
6640 that field, perform the mask operation. Then compare with the
6641 merged constant. */
6652 }
6653 \f
6654 /* T is an integer expression that is being multiplied, divided, or taken a
6655 modulus (CODE says which and what kind of divide or modulus) by a
6656 constant C. See if we can eliminate that operation by folding it with
6657 other operations already in T. WIDE_TYPE, if non-null, is a type that
6658 should be used for the computation if wider than our type.
6660 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6661 (X * 2) + (Y * 4). We must, however, be assured that either the original
6662 expression would not overflow or that overflow is undefined for the type
6663 in the language in question.
6665 If we return a non-null expression, it is an equivalent form of the
6666 original computation, but need not be in the original type.
6668 We set *STRICT_OVERFLOW_P to true if the return values depends on
6669 signed overflow being undefined. Otherwise we do not change
6670 *STRICT_OVERFLOW_P. */
6672 static tree
6675 {
6676 /* To avoid exponential search depth, refuse to allow recursion past
6677 three levels. Beyond that (1) it's highly unlikely that we'll find
6678 something interesting and (2) we've probably processed it before
6679 when we built the inner expression. */
6682 tree ret;
6687 depth++;
6689 depth--;
6692 }
6694 static tree
6697 {
6709 /* Don't deal with constants of zero here; they confuse the code below. */
6719 /* Note that we need not handle conditional operations here since fold
6720 already handles those cases. So just do arithmetic here. */
6722 {
6724 /* For a constant, we can always simplify if we are a multiply
6725 or (for divide and modulus) if it is a multiple of our constant. */
6729 {
6732 /* If the multiplication overflowed, we lost information on it.
6733 See PR68142 and PR69845. */
6737 }
6743 /* If op0 is an expression ... */
6749 /* ... and has wrapping overflow, and its type is smaller
6750 than ctype, then we cannot pass through as widening. */
6754 /* ... or this is a truncation (t is narrower than op0),
6755 then we cannot pass through this narrowing. */
6758 /* ... or signedness changes for division or modulus,
6759 then we cannot pass through this conversion. */
6763 /* ... or has undefined overflow while the converted to
6764 type has not, we cannot do the operation in the inner type
6765 as that would introduce undefined overflow. */
6770 /* Pass the constant down and see if we can make a simplification. If
6771 we can, replace this expression with the inner simplification for
6772 possible later conversion to our or some other type. */
6783 /* If widening the type changes it from signed to unsigned, then we
6784 must avoid building ABS_EXPR itself as unsigned. */
6786 {
6790 {
6793 }
6795 }
6796 /* If the constant is negative, we cannot simplify this. */
6799 /* FALLTHROUGH */
6801 /* For division and modulus, type can't be unsigned, as e.g.
6802 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6803 For signed types, even with wrapping overflow, this is fine. */
6812 /* If widening the type changes the signedness, then we can't perform
6813 this optimization as that changes the result. */
6817 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6823 {
6830 }
6834 /* If the second operand is constant, this is a multiplication
6835 or floor division, by a power of two, so we can treat it that
6836 way unless the multiplier or divisor overflows. Signed
6837 left-shift overflow is implementation-defined rather than
6838 undefined in C90, so do not convert signed left shift into
6839 multiplication. */
6842 /* const_binop may not detect overflow correctly,
6843 so check for it explicitly here. */
6852 ctype,
6854 t1),
6859 /* See if we can eliminate the operation on both sides. If we can, we
6860 can return a new PLUS or MINUS. If we can't, the only remaining
6861 cases where we can do anything are if the second operand is a
6862 constant. */
6869 /* If not multiplication, we can only do this if both operands
6870 are divisible by c. */
6873 {
6878 }
6880 /* If this was a subtraction, negate OP1 and set it to be an addition.
6881 This simplifies the logic below. */
6883 {
6885 /* If OP1 was not easily negatable, the constant may be OP0. */
6887 {
6890 }
6891 }
6896 /* If either OP1 or C are negative, this optimization is not safe for
6897 some of the division and remainder types while for others we need
6898 to change the code. */
6900 {
6908 }
6910 /* If it's a multiply or a division/modulus operation of a multiple
6911 of our constant, do the operation and verify it doesn't overflow. */
6915 {
6918 /* We allow the constant to overflow with wrapping semantics. */
6922 }
6923 else
6926 /* If we have an unsigned type, we cannot widen the operation since it
6927 will change the result if the original computation overflowed. */
6931 /* The last case is if we are a multiply. In that case, we can
6932 apply the distributive law to commute the multiply and addition
6933 if the multiplication of the constants doesn't overflow
6934 and overflow is defined. With undefined overflow
6935 op0 * c might overflow, while (op0 + orig_op1) * c doesn't.
6936 But fold_plusminus_mult_expr would factor back any power-of-two
6937 value so do not distribute in the first place in this case. */
6945 op1);
6950 /* We have a special case here if we are doing something like
6951 (C * 8) % 4 since we know that's zero. */
6954 /* If the multiplication can overflow we cannot optimize this. */
6959 {
6962 }
6964 /* ... fall through ... */
6968 /* If we can extract our operation from the LHS, do so and return a
6969 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6970 do something only if the second operand is a constant. */
6986 /* If these are the same operation types, we can associate them
6987 assuming no overflow. */
6989 {
7004 }
7006 /* If these operations "cancel" each other, we have the main
7007 optimizations of this pass, which occur when either constant is a
7008 multiple of the other, in which case we replace this with either an
7009 operation or CODE or TCODE.
7011 If we have an unsigned type, we cannot do this since it will change
7012 the result if the original computation overflowed. */
7019 {
7022 {
7029 }
7032 {
7039 }
7040 }
7045 }
7048 }
7049 \f
7050 /* Return a node which has the indicated constant VALUE (either 0 or
7051 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
7052 and is of the indicated TYPE. */
7054 tree
7056 {
7065 else
7067 }
7070 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
7071 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
7072 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
7073 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
7074 COND is the first argument to CODE; otherwise (as in the example
7075 given here), it is the second argument. TYPE is the type of the
7076 original expression. Return NULL_TREE if no simplification is
7077 possible. */
7079 static tree
7084 {
7092 /* Do not move possibly trapping operations into the conditional as this
7093 pessimizes code and causes gimplification issues when applied late. */
7101 {
7105 /* If this operand throws an expression, then it does not make
7106 sense to try to perform a logical or arithmetic operation
7107 involving it. */
7112 }
7115 {
7120 }
7121 else
7122 /* Detect the case of mixing vector and scalar types - bail out. */
7128 /* This transformation is only worthwhile if we don't have to wrap ARG
7129 in a SAVE_EXPR and the operation can be simplified without recursing
7130 on at least one of the branches once its pushed inside the COND_EXPR. */
7139 {
7143 else
7145 }
7147 {
7151 else
7153 }
7155 /* Check that we have simplified at least one of the branches. */
7160 }
7162 \f
7163 /* Subroutine of fold() that checks for the addition of ARG +/- 0.0.
7165 If !NEGATE, return true if ZERO_ARG is +/-0.0 and, for all ARG of
7166 type TYPE, ARG + ZERO_ARG is the same as ARG. If NEGATE, return true
7167 if ARG - ZERO_ARG is the same as X.
7169 If ARG is NULL, check for any value of type TYPE.
7171 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
7172 and finite. The problematic cases are when X is zero, and its mode
7173 has signed zeros. In the case of rounding towards -infinity,
7174 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
7175 modes, X + 0 is not the same as X because -0 + 0 is 0. */
7177 bool
7180 {
7184 /* Don't allow the fold with -fsignaling-nans. */
7188 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
7192 /* There is no case that is safe for all rounding modes. */
7196 /* In a vector or complex, we would need to check the sign of all zeros. */
7202 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
7206 /* The mode has signed zeros, and we have to honor their sign.
7207 In this situation, there are only two cases we can return true for.
7208 (i) X - 0 is the same as X with default rounding.
7209 (ii) X + 0 is X when X can't possibly be -0.0. */
7211 }
7213 /* Subroutine of match.pd that optimizes comparisons of a division by
7214 a nonzero integer constant against an integer constant, i.e.
7215 X/C1 op C2.
7217 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7218 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
7220 enum tree_code
7223 {
7228 /* We have to do this the hard way to detect unsigned overflow.
7229 prod = int_const_binop (MULT_EXPR, c1, c2); */
7235 {
7239 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
7242 }
7244 {
7247 {
7266 }
7267 }
7268 else
7269 {
7270 /* A negative divisor reverses the relational operators. */
7275 {
7294 }
7295 }
7308 }
7311 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7312 equality/inequality test, then return a simplified form of the test
7313 using a sign testing. Otherwise return NULL. TYPE is the desired
7314 result type. */
7316 static tree
7319 tree result_type)
7320 {
7321 /* If this is testing a single bit, we can optimize the test. */
7325 {
7326 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7327 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7331 /* This is only a win if casting to a signed type is cheap,
7332 i.e. when arg00's type is not a partial mode. */
7334 {
7337 result_type,
7340 }
7341 }
7344 }
7346 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7347 equality/inequality test, then return a simplified form of
7348 the test using shifts and logical operations. Otherwise return
7349 NULL. TYPE is the desired result type. */
7351 tree
7354 {
7355 /* If this is testing a single bit, we can optimize the test. */
7359 {
7368 /* First, see if we can fold the single bit test into a sign-bit
7369 test. */
7371 result_type);
7375 /* Otherwise we have (A & C) != 0 where C is a single bit,
7376 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7377 Similarly for (A & C) == 0. */
7379 /* If INNER is a right shift of a constant and it plus BITNUM does
7380 not overflow, adjust BITNUM and INNER. */
7386 {
7389 }
7391 /* If we are going to be able to omit the AND below, we must do our
7392 operations as unsigned. If we must use the AND, we have a choice.
7393 Normally unsigned is faster, but for some machines signed is. */
7411 /* Put the AND last so it can combine with more things. */
7414 /* Make sure to return the proper type. */
7418 }
7420 }
7422 /* Test whether it is preferable to swap two operands, ARG0 and
7423 ARG1, for example because ARG0 is an integer constant and ARG1
7424 isn't. */
7426 bool
7428 {
7442 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7443 for commutative and comparison operators. Ensuring a canonical
7444 form allows the optimizers to find additional redundancies without
7445 having to explicitly check for both orderings. */
7451 /* Put SSA_NAMEs last. */
7457 /* Put variables last. */
7464 }
7467 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7468 means A >= Y && A != MAX, but in this case we know that
7469 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7471 static tree
7473 {
7480 else
7489 {
7492 }
7494 {
7497 }
7498 else
7505 {
7506 /* Convert the pointer types into integer before taking the difference. */
7510 }
7511 else
7518 }
7520 /* Fold a sum or difference of at least one multiplication.
7521 Returns the folded tree or NULL if no simplification could be made. */
7523 static tree
7526 {
7530 /* (A * C) +- (B * C) -> (A+-B) * C.
7531 (A * C) +- A -> A * (C+-1).
7532 We are most concerned about the case where C is a constant,
7533 but other combinations show up during loop reduction. Since
7534 it is not difficult, try all four possibilities. */
7537 {
7540 }
7542 {
7545 }
7546 else
7547 {
7548 /* We cannot generate constant 1 for fract. */
7553 }
7555 {
7558 }
7560 {
7562 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7563 the purpose of this canonicalization. */
7567 {
7570 }
7571 else
7573 }
7574 else
7575 {
7576 /* We cannot generate constant 1 for fract. */
7581 }
7584 /* Prefer factoring a common non-constant. */
7594 /* No identical multiplicands; see if we can find a common
7595 power-of-two factor in non-power-of-two multiplies. This
7596 can help in multi-dimensional array access. */
7598 {
7601 HOST_WIDE_INT tmp;
7603 tree maybe_same;
7605 /* Move min of absolute values to int11. */
7607 {
7612 }
7613 else
7620 /* The remainder should not be a constant, otherwise we
7621 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7622 increased the number of multiplications necessary. */
7624 {
7632 }
7633 }
7640 /* We are neither factoring zero nor minus one. */
7648 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7649 same may be minus one and thus the multiplication may overflow. Perform
7650 the sum operation in an unsigned type. */
7655 /* If the sum evaluated to a constant that is not -INF the multiplication
7656 cannot overflow. */
7663 /* Do not resort to unsigned multiplication because
7664 we lose the no-overflow property of the expression. */
7666 }
7668 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7669 specified by EXPR into the buffer PTR of length LEN bytes.
7670 Return the number of bytes placed in the buffer, or zero
7671 upon failure. */
7673 static int
7675 {
7687 /* Dry run. */
7693 {
7695 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7696 number of bytes. */
7700 {
7707 else
7709 }
7710 else
7714 }
7716 }
7719 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7720 specified by EXPR into the buffer PTR of length LEN bytes.
7721 Return the number of bytes placed in the buffer, or zero
7722 upon failure. */
7724 static int
7726 {
7730 FIXED_VALUE_TYPE value;
7745 }
7748 /* Subroutine of native_encode_expr. Encode the REAL_CST
7749 specified by EXPR into the buffer PTR of length LEN bytes.
7750 Return the number of bytes placed in the buffer, or zero
7751 upon failure. */
7753 static int
7755 {
7761 /* There are always 32 bits in each long, no matter the size of
7762 the hosts long. We handle floating point representations with
7763 up to 192 bits. */
7772 /* Dry run. */
7781 {
7786 {
7793 else
7795 }
7796 else
7797 {
7800 {
7801 /* Reverse bytes within each long, or within the entire float
7802 if it's smaller than a long (for HFmode). */
7805 }
7806 }
7811 }
7813 }
7815 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7816 specified by EXPR into the buffer PTR of length LEN bytes.
7817 Return the number of bytes placed in the buffer, or zero
7818 upon failure. */
7820 static int
7822 {
7824 tree part;
7838 }
7840 /* Like native_encode_vector, but only encode the first COUNT elements.
7841 The other arguments are as for native_encode_vector. */
7843 static int
7846 {
7850 {
7851 /* This is the only case in which elements can be smaller than a byte.
7852 Element 0 is always in the lsb of the containing byte. */
7861 /* Zero the buffer and then set bits later where necessary. */
7870 {
7876 {
7879 }
7880 }
7882 }
7887 {
7889 {
7892 }
7903 }
7905 }
7907 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7908 specified by EXPR into the buffer PTR of length LEN bytes.
7909 Return the number of bytes placed in the buffer, or zero
7910 upon failure. */
7912 static int
7914 {
7919 }
7922 /* Subroutine of native_encode_expr. Encode the STRING_CST
7923 specified by EXPR into the buffer PTR of length LEN bytes.
7924 Return the number of bytes placed in the buffer, or zero
7925 upon failure. */
7927 static int
7929 {
7932 /* Wide-char strings are encoded in target byte-order so native
7933 encoding them is trivial. */
7948 else
7949 {
7952 {
7955 }
7957 }
7959 }
7962 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST, REAL_CST,
7963 FIXED_CST, COMPLEX_CST, STRING_CST, or VECTOR_CST specified by EXPR into
7964 the buffer PTR of size LEN bytes. If PTR is NULL, don't actually store
7965 anything, just do a dry run. Fail either if OFF is -1 and LEN isn't
7966 sufficient to encode the entire EXPR, or if OFF is out of bounds.
7967 Otherwise, start at byte offset OFF and encode at most LEN bytes.
7968 Return the number of bytes placed in the buffer, or zero upon failure. */
7970 int
7972 {
7973 /* We don't support starting at negative offset and -1 is special. */
7978 {
7999 }
8000 }
8002 /* Try to find a type whose byte size is smaller or equal to LEN bytes larger
8003 or equal to FIELDSIZE bytes, with underlying mode precision/size multiple
8004 of BITS_PER_UNIT. As native_{interpret,encode}_int works in term of
8005 machine modes, we can't just use build_nonstandard_integer_type. */
8007 tree
8009 {
8010 machine_mode mode;
8012 {
8019 {
8023 }
8024 }
8030 {
8038 }
8041 }
8043 /* Similar to native_encode_expr, but also handle CONSTRUCTORs, VCEs,
8044 NON_LVALUE_EXPRs and nops. If MASK is non-NULL (then PTR has
8045 to be non-NULL and OFF zero), then in addition to filling the
8046 bytes pointed by PTR with the value also clear any bits pointed
8047 by MASK that are known to be initialized, keep them as is for
8048 e.g. uninitialized padding bits or uninitialized fields. */
8050 int
8053 {
8056 /* We don't support starting at negative offset and -1 is special. */
8064 {
8068 mask);
8083 {
8084 tree min_index;
8102 {
8107 {
8110 }
8115 else
8119 {
8123 offset_int wpos
8131 offset_int wcount
8138 }
8140 {
8143 offset_int wpos
8151 }
8154 {
8156 {
8167 }
8169 {
8173 }
8174 }
8178 do
8179 {
8184 {
8186 {
8189 fieldsize);
8192 }
8194 ptr
8197 fieldsize,
8200 mask
8204 else
8205 {
8208 }
8209 }
8212 {
8213 /* Partial overlap. */
8219 {
8223 fieldsize);
8224 }
8225 else
8226 {
8230 }
8233 }
8235 }
8237 }
8239 }
8242 {
8252 {
8258 {
8261 }
8264 {
8273 }
8277 else
8281 {
8282 tree fld;
8284 {
8297 }
8299 {
8303 }
8306 {
8307 cnt--;
8313 }
8314 }
8319 {
8332 {
8337 }
8338 }
8339 else
8340 {
8345 }
8350 {
8357 else
8363 }
8372 {
8373 /* FIXME: Handle PDP endian. */
8384 {
8387 }
8388 else
8389 {
8397 else
8398 {
8401 }
8402 }
8412 else
8425 /* If the bitfield does not start at byte boundary, handle
8426 the partial byte at the start. */
8429 {
8431 {
8436 {
8439 else
8441 }
8442 }
8443 else
8444 {
8449 {
8452 else
8456 }
8457 }
8458 }
8459 /* If the bitfield does not end at byte boundary, handle
8460 the partial byte at the end. */
8464 {
8466 {
8473 }
8474 else
8475 {
8482 }
8483 }
8487 {
8492 }
8493 else
8494 {
8495 /* Partial overlap. */
8499 {
8502 }
8506 }
8508 }
8513 {
8516 {
8519 {
8523 }
8526 }
8529 fldsize,
8539 }
8540 else
8541 {
8542 /* Partial overlap. */
8548 {
8552 fieldsize);
8553 }
8554 else
8555 {
8559 }
8562 }
8563 }
8565 }
8567 }
8568 }
8571 /* Subroutine of native_interpret_expr. Interpret the contents of
8572 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8573 If the buffer cannot be interpreted, return NULL_TREE. */
8575 static tree
8577 {
8587 }
8590 /* Subroutine of native_interpret_expr. Interpret the contents of
8591 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
8592 If the buffer cannot be interpreted, return NULL_TREE. */
8594 static tree
8596 {
8599 double_int result;
8600 FIXED_VALUE_TYPE fixed_value;
8610 }
8613 /* Subroutine of native_interpret_expr. Interpret the contents of
8614 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8615 If the buffer cannot be interpreted, return NULL_TREE. */
8617 static tree
8619 {
8623 /* There are always 32 bits in each long, no matter the size of
8624 the hosts long. We handle floating point representations with
8625 up to 192 bits. */
8626 REAL_VALUE_TYPE r;
8636 {
8637 /* Both OFFSET and BYTE index within a long;
8638 bitpos indexes the whole float. */
8641 {
8648 else
8650 }
8651 else
8652 {
8655 {
8656 /* Reverse bytes within each long, or within the entire float
8657 if it's smaller than a long (for HFmode). */
8660 }
8661 }
8665 }
8670 {
8671 /* For floating point values in composite modes, punt if this folding
8672 doesn't preserve bit representation. As the mode doesn't have fixed
8673 precision while GCC pretends it does, there could be valid values that
8674 GCC can't really represent accurately. See PR95450. */
8679 }
8681 }
8684 /* Subroutine of native_interpret_expr. Interpret the contents of
8685 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8686 If the buffer cannot be interpreted, return NULL_TREE. */
8688 static tree
8690 {
8705 }
8707 /* Read a vector of type TYPE from the target memory image given by BYTES,
8708 which contains LEN bytes. The vector is known to be encodable using
8709 NPATTERNS interleaved patterns with NELTS_PER_PATTERN elements each.
8711 Return the vector on success, otherwise return null. */
8713 static tree
8717 {
8721 {
8722 /* This is the only case in which elements can be smaller than a byte.
8723 Element 0 is always in the lsb of the containing byte. */
8730 {
8737 }
8739 }
8747 {
8753 }
8755 }
8757 /* Subroutine of native_interpret_expr. Interpret the contents of
8758 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8759 If the buffer cannot be interpreted, return NULL_TREE. */
8761 static tree
8763 {
8764 tree etype;
8775 }
8778 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8779 the buffer PTR of length LEN as a constant of type TYPE. For
8780 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8781 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8782 return NULL_TREE. */
8784 tree
8786 {
8788 {
8811 }
8812 }
8814 /* Returns true if we can interpret the contents of a native encoding
8815 as TYPE. */
8817 bool
8819 {
8821 {
8835 }
8836 }
8838 /* Attempt to interpret aggregate of TYPE from bytes encoded in target
8839 byte order at PTR + OFF with LEN bytes. Does not handle unions. */
8841 tree
8844 {
8847 {
8854 {
8858 }
8863 {
8868 {
8873 }
8877 eltsz);
8881 }
8883 }
8887 {
8895 {
8898 {
8899 poly_int64 bitoffset;
8904 else
8914 }
8915 else
8916 {
8934 HOST_WIDE_INT rpos;
8937 else
8938 {
8941 }
8950 }
8951 }
8954 {
8964 }
8968 {
8973 }
8980 {
8984 /* FIXME: Figure out how to handle PDP endian bitfields. */
8990 else
8994 }
8996 }
8998 }
9000 /* Routines for manipulation of native_encode_expr encoded data if the encoded
9001 or extracted constant positions and/or sizes aren't byte aligned. */
9003 /* Shift left the bytes in PTR of SZ elements by AMNT bits, carrying over the
9004 bits between adjacent elements. AMNT should be within
9005 [0, BITS_PER_UNIT).
9006 Example, AMNT = 2:
9007 00011111|11100000 << 2 = 01111111|10000000
9008 PTR[1] | PTR[0] PTR[1] | PTR[0]. */
9010 void
9013 {
9022 {
9028 {
9031 }
9032 }
9033 }
9035 /* Like shift_bytes_in_array_left but for big-endian.
9036 Shift right the bytes in PTR of SZ elements by AMNT bits, carrying over the
9037 bits between adjacent elements. AMNT should be within
9038 [0, BITS_PER_UNIT).
9039 Example, AMNT = 2:
9040 00011111|11100000 >> 2 = 00000111|11111000
9041 PTR[0] | PTR[1] PTR[0] | PTR[1]. */
9043 void
9046 {
9054 {
9061 }
9062 }
9064 /* Try to view-convert VECTOR_CST EXPR to VECTOR_TYPE TYPE by operating
9065 directly on the VECTOR_CST encoding, in a way that works for variable-
9066 length vectors. Return the resulting VECTOR_CST on success or null
9067 on failure. */
9069 static tree
9071 {
9083 /* We can only preserve the semantics of a stepped pattern if the new
9084 vector element is an integer of the same size. */
9089 /* The number of bits needed to encode one element from every pattern
9090 of the original vector. */
9091 unsigned int expr_sequence_bits
9094 /* The number of bits needed to encode one element from every pattern
9095 of the result. */
9096 unsigned int type_sequence_bits
9099 /* Don't try to read more bytes than are available, which can happen
9100 for constant-sized vectors if TYPE has larger elements than EXPR_TYPE.
9101 The general VIEW_CONVERT handling can cope with that case, so there's
9102 no point complicating things here. */
9105 BITS_PER_UNIT);
9110 /* Get enough bytes of EXPR to form the new encoding. */
9118 /* Reencode the bytes as TYPE. */
9122 }
9124 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
9125 TYPE at compile-time. If we're unable to perform the conversion
9126 return NULL_TREE. */
9128 static tree
9130 {
9131 /* We support up to 512-bit values (for V8DFmode). */
9135 /* Check that the host and target are sane. */
9148 }
9150 /* Build an expression for the address of T. Folds away INDIRECT_REF
9151 to avoid confusing the gimplify process. */
9153 tree
9155 {
9156 /* The size of the object is not relevant when talking about its address. */
9161 {
9166 }
9169 {
9174 }
9181 {
9186 }
9187 else
9191 }
9193 /* Build an expression for the address of T. */
9195 tree
9197 {
9201 }
9203 /* Fold a unary expression of code CODE and type TYPE with operand
9204 OP0. Return the folded expression if folding is successful.
9205 Otherwise, return NULL_TREE. */
9207 tree
9209 {
9210 tree tem;
9211 tree arg0;
9219 {
9222 {
9223 /* Don't use STRIP_NOPS, because signedness of argument type
9224 matters. */
9226 }
9227 else
9228 {
9229 /* Strip any conversions that don't change the mode. This
9230 is safe for every expression, except for a comparison
9231 expression because its signedness is derived from its
9232 operands.
9234 Note that this is done as an internal manipulation within
9235 the constant folder, in order to find the simplest
9236 representation of the arguments so that their form can be
9237 studied. In any cases, the appropriate type conversions
9238 should be put back in the tree that will get out of the
9239 constant folder. */
9241 }
9244 {
9247 {
9251 }
9252 }
9253 }
9260 {
9267 {
9281 /* If this was a conversion, and all we did was to move into
9282 inside the COND_EXPR, bring it back out. But leave it if
9283 it is a conversion from integer to integer and the
9284 result precision is no wider than a word since such a
9285 conversion is cheap and may be optimized away by combine,
9286 while it couldn't if it were outside the COND_EXPR. Then return
9287 so we don't get into an infinite recursion loop taking the
9288 conversion out and then back in. */
9300 && (INTEGRAL_TYPE_P
9313 }
9314 }
9317 {
9323 CASE_CONVERT:
9327 {
9328 /* If we have (type) (a CMP b) and type is an integral type, return
9329 new expression involving the new type. Canonicalize
9330 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
9331 non-integral type.
9332 Do not fold the result as that would not simplify further, also
9333 folding again results in recursions. */
9343 }
9345 /* Handle (T *)&A.B.C for A being of type T and B and C
9346 living at offset zero. This occurs frequently in
9347 C++ upcasting and then accessing the base. */
9351 {
9353 tree offset;
9354 machine_mode mode;
9356 tree base
9360 /* If the reference was to a (constant) zero offset, we can use
9361 the address of the base if it has the same base type
9362 as the result type and the pointer type is unqualified. */
9370 }
9374 /* Detect assigning a bitfield. */
9376 && DECL_BIT_FIELD
9378 {
9379 /* Don't leave an assignment inside a conversion
9380 unless assigning a bitfield. */
9382 /* First do the assignment, then return converted constant. */
9387 }
9389 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
9390 constants (if x has signed type, the sign bit cannot be set
9391 in c). This folds extension into the BIT_AND_EXPR.
9392 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
9393 very likely don't have maximal range for their precision and this
9394 transformation effectively doesn't preserve non-maximal ranges. */
9398 {
9409 <= HOST_BITS_PER_WIDE_INT
9411 {
9415 cst &= HOST_WIDE_INT_M1U
9419 && !flag_syntax_only
9422 {
9426 }
9427 }
9429 {
9434 }
9435 }
9437 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
9438 cast (T1)X will fold away. We assume that this happens when X itself
9439 is a cast. */
9443 {
9447 /* If -fsanitize=alignment, avoid this optimization in GENERIC
9448 when the pointed type needs higher alignment than
9449 the p+ first operand's pointed type. */
9458 }
9460 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
9461 of the same precision, and X is an integer type not narrower than
9462 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
9468 {
9474 }
9476 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
9477 type of X and Y (integer types only). */
9482 {
9483 /* Be careful not to introduce new overflows. */
9484 tree mult_type;
9487 else
9491 {
9498 }
9499 }
9505 {
9512 }
9523 /* Convert fabs((double)float) into (double)fabsf(float). */
9526 {
9532 targ0));
9533 }
9537 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
9556 /* Note that the operand of this must be an int
9557 and its values must be 0 or 1.
9558 ("true" is a fixed value perhaps depending on the language,
9559 but we don't handle values other than 1 correctly yet.) */
9566 /* Fold *&X to X if X is an lvalue. */
9568 {
9575 }
9581 }
9584 /* If the operation was a conversion do _not_ mark a resulting constant
9585 with TREE_OVERFLOW if the original constant was not. These conversions
9586 have implementation defined behavior and retaining the TREE_OVERFLOW
9587 flag here would confuse later passes such as VRP. */
9588 tree
9591 {
9600 }
9602 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
9603 operands OP0 and OP1. LOC is the location of the resulting expression.
9604 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
9605 Return the folded expression if folding is successful. Otherwise,
9606 return NULL_TREE. */
9607 static tree
9610 {
9611 tree tem;
9613 /* We only do these simplifications if we are optimizing. */
9617 /* Check for things like (A || B) && (A || C). We can convert this
9618 to A || (B && C). Note that either operator can be any of the four
9619 truth and/or operations and the transformation will still be
9620 valid. Also note that we only care about order for the
9621 ANDIF and ORIF operators. If B contains side effects, this
9622 might change the truth-value of A. */
9629 {
9649 /* This case if tricky because we must either have commutative
9650 operators or else A10 must not have side-effects. */
9656 a01);
9657 }
9659 /* See if we can build a range comparison. */
9665 {
9669 }
9673 {
9677 }
9679 /* Check for the possibility of merging component references. If our
9680 lhs is another similar operation, try to merge its rhs with our
9681 rhs. Then try to merge our lhs and rhs. */
9692 logical_op_non_short_circuit
9700 {
9707 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
9708 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
9709 We don't want to pack more than two leafs to a non-IF AND/OR
9710 expression.
9711 If tree-code of left-hand operand isn't an AND/OR-IF code and not
9712 equal to IF-CODE, then we don't want to add right-hand operand.
9713 If the inner right-hand side of left-hand operand has
9714 side-effects, or isn't simple, then we can't add to it,
9715 as otherwise we might destroy if-sequence. */
9718 /* Needed for sequence points to handle trappings, and
9719 side-effects. */
9721 {
9723 arg1);
9725 tem);
9726 }
9727 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
9728 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
9731 /* Needed for sequence points to handle trappings, and
9732 side-effects. */
9734 {
9739 }
9740 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
9741 into (A OR B).
9742 For sequence point consistancy, we need to check for trapping,
9743 and side-effects. */
9747 }
9750 }
9752 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9753 by changing CODE to reduce the magnitude of constants involved in
9754 ARG0 of the comparison.
9755 Returns a canonicalized comparison tree if a simplification was
9756 possible, otherwise returns NULL_TREE.
9757 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9758 valid if signed overflow is undefined. */
9760 static tree
9764 {
9769 /* Match A +- CST code arg1. We can change this only if overflow
9770 is undefined. */
9773 /* In principle pointers also have undefined overflow behavior,
9774 but that causes problems elsewhere. */
9781 /* Identify the constant in arg0 and its sign. */
9785 /* Overflowed constants and zero will cause problems. */
9790 /* See if we can reduce the magnitude of the constant in
9791 arg0 by changing the comparison code. */
9792 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9796 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9800 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9804 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9808 else
9812 /* Now build the constant reduced in magnitude. But not if that
9813 would produce one outside of its types range. */
9829 }
9831 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9832 overflow further. Try to decrease the magnitude of constants involved
9833 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9834 and put sole constants at the second argument position.
9835 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9837 static tree
9840 {
9841 tree t;
9846 /* Try canonicalization by simplifying arg0. */
9851 {
9855 }
9857 /* Try canonicalization by simplifying arg1 using the swapped
9858 comparison. */
9866 }
9868 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9869 space. This is used to avoid issuing overflow warnings for
9870 expressions like &p->x which cannot wrap. */
9872 static bool
9874 {
9881 poly_wide_int wi_offset;
9887 else
9892 precision);
9907 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9908 array. */
9917 }
9919 /* Return a positive integer when the symbol DECL is known to have
9920 a nonzero address, zero when it's known not to (e.g., it's a weak
9921 symbol), and a negative integer when the symbol is not yet in the
9922 symbol table and so whether or not its address is zero is unknown.
9923 For function local objects always return positive integer. */
9924 static int
9926 {
9927 /* Normally, don't do anything for variables and functions before symtab is
9928 built; it is quite possible that DECL will be declared weak later.
9929 But if folding_initializer, we need a constant answer now, so create
9930 the symtab entry and prevent later weak declaration. */
9933 = (folding_initializer
9938 /* Function local objects are never NULL. */
9946 }
9948 /* Subroutine of fold_binary. This routine performs all of the
9949 transformations that are common to the equality/inequality
9950 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9951 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9952 fold_binary should call fold_binary. Fold a comparison with
9953 tree code CODE and type TYPE with operands OP0 and OP1. Return
9954 the folded comparison or NULL_TREE. */
9956 static tree
9959 {
9969 /* For comparisons of pointers we can decompose it to a compile time
9970 comparison of the base objects and the offsets into the object.
9971 This requires at least one operand being an ADDR_EXPR or a
9972 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9978 {
9981 machine_mode mode;
9985 /* Get base and offset for the access. Strip ADDR_EXPR for
9986 get_inner_reference, but put it back by stripping INDIRECT_REF
9987 off the base object if possible. indirect_baseN will be true
9988 if baseN is not an address but refers to the object itself. */
9991 {
9992 base0
9998 else
10000 }
10002 {
10006 {
10007 base0
10013 else
10015 }
10018 else
10022 {
10029 }
10030 }
10034 {
10035 base1
10041 else
10043 }
10045 {
10049 {
10050 base1
10056 else
10058 }
10061 else
10065 {
10072 }
10073 }
10075 /* If we have equivalent bases we might be able to simplify. */
10079 {
10080 /* We can fold this expression to a constant if the non-constant
10081 offset parts are equal. */
10085 && (equality_code
10086 || (indirect_base0
10089 {
10095 "occur when comparing P +- C1 with "
10097 WARN_STRICT_OVERFLOW_CONDITIONAL);
10100 {
10138 }
10139 }
10140 /* We can simplify the comparison to a comparison of the variable
10141 offset parts if the constant offset parts are equal.
10142 Be careful to use signed sizetype here because otherwise we
10143 mess with array offsets in the wrong way. This is possible
10144 because pointer arithmetic is restricted to retain within an
10145 object and overflow on pointer differences is undefined as of
10146 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
10148 && (equality_code
10149 || (indirect_base0
10152 {
10153 /* By converting to signed sizetype we cover middle-end pointer
10154 arithmetic which operates on unsigned pointer types of size
10155 type size and ARRAY_REF offsets which are properly sign or
10156 zero extended from their type in case it is narrower than
10157 sizetype. */
10160 else
10164 else
10171 "occur when comparing P +- C1 with "
10173 WARN_STRICT_OVERFLOW_COMPARISON);
10176 }
10177 }
10178 /* For equal offsets we can simplify to a comparison of the
10179 base addresses. */
10181 && (indirect_base0
10183 && (indirect_base1
10188 {
10194 }
10195 /* Comparison between an ordinary (non-weak) symbol and a null
10196 pointer can be eliminated since such symbols must have a non
10197 null address. In C, relational expressions between pointers
10198 to objects and null pointers are undefined. The results
10199 below follow the C++ rules with the additional property that
10200 every object pointer compares greater than a null pointer.
10201 */
10204 /* Avoid folding references to struct members at offset 0 to
10205 prevent tests like '&ptr->firstmember == 0' from getting
10206 eliminated. When ptr is null, although the -> expression
10207 is strictly speaking invalid, GCC retains it as a matter
10208 of QoI. See PR c/44555. */
10211 && indirect_base0
10212 /* The caller guarantees that when one of the arguments is
10213 constant (i.e., null in this case) it is second. */
10215 {
10217 {
10228 }
10229 }
10230 }
10232 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
10233 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
10234 the resulting offset is smaller in absolute value than the
10235 original one and has the same sign. */
10244 {
10249 tree cst;
10251 "occur when combining constants around "
10254 /* Put the constant on the side where it doesn't overflow and is
10255 of lower absolute value and of same sign than before. */
10262 {
10265 variable1,
10269 }
10277 {
10283 variable2);
10284 }
10285 }
10291 /* If we are comparing an expression that just has comparisons
10292 of two integer values, arithmetic expressions of those comparisons,
10293 and constants, we can simplify it. There are only three cases
10294 to check: the two values can either be equal, the first can be
10295 greater, or the second can be greater. Fold the expression for
10296 those three values. Since each value must be 0 or 1, we have
10297 eight possibilities, each of which corresponds to the constant 0
10298 or 1 or one of the six possible comparisons.
10300 This handles common cases like (a > b) == 0 but also handles
10301 expressions like ((x > y) - (y > x)) > 0, which supposedly
10302 occur in macroized code. */
10305 {
10309 /* Don't handle degenerate cases here; they should already
10310 have been handled anyway. */
10319 {
10323 /* We can't just pass T to eval_subst in case cval1 or cval2
10324 was the same as ARG1. */
10326 tree high_result
10330 arg1);
10331 tree equal_result
10335 arg1);
10336 tree low_result
10340 arg1);
10342 /* All three of these results should be 0 or 1. Confirm they are.
10343 Then use those values to select the proper code to use. */
10348 {
10349 /* Make a 3-bit mask with the high-order bit being the
10350 value for `>', the next for '=', and the low for '<'. */
10354 {
10356 /* Always false. */
10377 /* Always true. */
10379 }
10382 }
10383 }
10384 }
10387 }
10390 /* Subroutine of fold_binary. Optimize complex multiplications of the
10391 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
10392 argument EXPR represents the expression "z" of type TYPE. */
10394 static tree
10396 {
10401 {
10404 }
10406 {
10409 }
10410 else
10411 {
10415 }
10424 }
10427 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
10428 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
10429 true if successful. */
10431 static bool
10433 {
10438 {
10441 }
10443 {
10449 else
10451 }
10452 else
10458 }
10460 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
10461 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
10462 NULL_TREE otherwise. */
10464 tree
10466 {
10487 {
10488 HOST_WIDE_INT index;
10494 }
10497 {
10503 }
10504 else
10506 }
10508 /* Try to fold a pointer difference of type TYPE two address expressions of
10509 array references AREF0 and AREF1 using location LOC. Return a
10510 simplified expression for the difference or NULL_TREE. */
10512 static tree
10516 {
10521 /* If the bases are array references as well, recurse. If the bases
10522 are pointer indirections compute the difference of the pointers.
10523 If the bases are equal, we are set. */
10526 && (base_offset
10528 use_pointer_diff)))
10531 && (base_offset
10532 = use_pointer_diff
10542 {
10548 base_offset,
10551 }
10553 }
10555 /* If the real or vector real constant CST of type TYPE has an exact
10556 inverse, return it, else return NULL. */
10558 tree
10560 {
10561 REAL_VALUE_TYPE r;
10562 tree unit_type;
10563 machine_mode mode;
10566 {
10576 {
10580 tree_vector_builder elts;
10585 {
10590 }
10593 }
10597 }
10598 }
10600 /* Mask out the tz least significant bits of X of type TYPE where
10601 tz is the number of trailing zeroes in Y. */
10602 static wide_int
10604 {
10609 }
10611 /* Return true when T is an address and is known to be nonzero.
10612 For floating point we further ensure that T is not denormal.
10613 Similar logic is present in nonzero_address in rtlanal.h.
10615 If the return value is based on the assumption that signed overflow
10616 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
10617 change *STRICT_OVERFLOW_P. */
10619 static bool
10621 {
10625 /* Doing something useful for floating point would need more work. */
10631 {
10634 strict_overflow_p);
10640 strict_overflow_p);
10648 }
10651 {
10654 strict_overflow_p);
10662 strict_overflow_p);
10677 strict_overflow_p);
10681 strict_overflow_p);
10684 {
10696 }
10700 }
10702 }
10704 /* Return true when T is an address and is known to be nonzero.
10705 Handle warnings about undefined signed overflow. */
10707 bool
10709 {
10716 "determining that expression is always "
10718 WARN_STRICT_OVERFLOW_MISC);
10720 }
10722 /* Return true if T is known not to be equal to an integer W. */
10724 bool
10726 {
10727 value_range vr;
10729 {
10739 else
10745 /* If T has some known zero bits and W has any of those bits set,
10746 then T is known not to be equal to W. */
10754 }
10755 }
10757 /* Fold a binary expression of code CODE and type TYPE with operands
10758 OP0 and OP1. LOC is the location of the resulting expression.
10759 Return the folded expression if folding is successful. Otherwise,
10760 return NULL_TREE. */
10762 tree
10765 {
10780 /* Strip any conversions that don't change the mode. This is
10781 safe for every expression, except for a comparison expression
10782 because its signedness is derived from its operands. So, in
10783 the latter case, only strip conversions that don't change the
10784 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10785 preserved.
10787 Note that this is done as an internal manipulation within the
10788 constant folder, in order to find the simplest representation
10789 of the arguments so that their form can be studied. In any
10790 cases, the appropriate type conversions should be put back in
10791 the tree that will get out of the constant folder. */
10794 {
10797 }
10798 else
10799 {
10802 }
10804 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10805 constant but we can't do arithmetic on them. */
10807 {
10810 {
10814 }
10815 }
10817 /* If this is a commutative operation, and ARG0 is a constant, move it
10818 to ARG1 to reduce the number of tests below. */
10823 /* Likewise if this is a comparison, and ARG0 is a constant, move it
10824 to ARG1 to reduce the number of tests below. */
10833 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10835 First check for cases where an arithmetic operation is applied to a
10836 compound, conditional, or comparison operation. Push the arithmetic
10837 operation inside the compound or conditional to see if any folding
10838 can then be done. Convert comparison to conditional for this purpose.
10839 The also optimizes non-constant cases that used to be done in
10840 expand_expr.
10842 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10843 one of the operands is a comparison and the other is a comparison, a
10844 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10845 code below would make the expression more complex. Change it to a
10846 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10847 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10860 {
10864 boolean_type_node,
10872 }
10876 {
10878 {
10883 tem);
10884 }
10886 {
10891 tem);
10892 }
10897 {
10903 }
10908 {
10914 }
10915 }
10918 {
10920 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10923 {
10929 }
10931 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10934 {
10935 tree base;
10936 poly_int64 coffset;
10945 }
10950 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10956 arg1),
10958 arg0)));
10964 {
10965 /* X + (X / CST) * -CST is X % CST. */
10970 {
10979 cst0));
10980 }
10981 }
10983 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10984 one. Make sure the type is not saturating and has the signedness of
10985 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10986 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10993 {
10997 }
11000 {
11001 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
11002 (plus (plus (mult) (mult)) (foo)) so that we can
11003 take advantage of the factoring cases below. */
11012 {
11018 else
11031 parg0),
11033 marg)),
11037 return
11043 parg1)));
11044 }
11045 }
11046 else
11047 {
11048 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
11049 to __complex__ ( x, y ). This is not the same for SNaNs or
11050 if signed zeros are involved. */
11054 {
11061 {
11065 {
11071 }
11073 {
11079 }
11080 }
11081 }
11083 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
11084 We associate floats only if the user has specified
11085 -fassociative-math. */
11089 {
11094 {
11095 tree tree0;
11098 }
11099 }
11100 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
11101 We associate floats only if the user has specified
11102 -fassociative-math. */
11106 {
11111 {
11112 tree tree0;
11115 }
11116 }
11117 }
11119 bit_rotate:
11120 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
11121 is a rotate of A by C1 bits. */
11122 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
11123 is a rotate of A by B bits.
11124 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
11125 though in this case CODE must be | and not + or ^, otherwise
11126 it doesn't return A when B is 0. */
11127 {
11129 tree rtype;
11138 /* Only create rotates in complete modes. Other cases are not
11139 expanded properly. */
11142 {
11155 {
11160 }
11165 {
11168 code0 == LSHIFT_EXPR
11171 }
11173 {
11183 {
11187 orig_tree01);
11189 }
11190 }
11194 {
11205 {
11209 orig_tree01);
11211 }
11212 }
11213 }
11214 }
11216 associate:
11217 /* In most languages, can't associate operations on floats through
11218 parentheses. Rather than remember where the parentheses were, we
11219 don't associate floats at all, unless the user has specified
11220 -fassociative-math.
11221 And, we need to make sure type is not saturating. */
11225 {
11231 /* Split both trees into variables, constants, and literals. Then
11232 associate each group together, the constants with literals,
11233 then the result with variables. This increases the chances of
11234 literals being recombined later and of generating relocatable
11235 expressions for the sum of a constant and literal. */
11243 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
11247 /* With undefined overflow prefer doing association in a type
11248 which wraps on overflow, if that is one of the operand types. */
11251 {
11259 }
11261 /* With undefined overflow we can only associate constants with one
11262 variable, and constants whose association doesn't overflow. */
11265 {
11267 {
11268 /* ??? If split_tree would handle NEGATE_EXPR we could
11269 simply reject these cases and the allowed cases would
11270 be the var0/minus_var1 ones. */
11276 {
11279 }
11286 {
11289 }
11295 /* The only case we can still associate with two variables
11296 is if they cancel out. */
11300 }
11306 }
11308 /* Only do something if we found more than two objects. Otherwise,
11309 nothing has changed and we risk infinite recursion. */
11317 {
11329 {
11333 }
11335 {
11339 }
11341 /* Preserve the MINUS_EXPR if the negative part of the literal is
11342 greater than the positive part. Otherwise, the multiplicative
11343 folding code (i.e extract_muldiv) may be fooled in case
11344 unsigned constants are subtracted, like in the following
11345 example: ((X*2 + 4) - 8U)/2. */
11347 {
11351 /* But avoid ending up with only negated parts. */
11353 {
11357 }
11358 else
11359 {
11363 }
11364 }
11366 /* Don't introduce overflows through reassociation. */
11371 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
11378 /* Eliminate minus_con0. */
11380 {
11387 else
11390 }
11392 /* Eliminate minus_var0. */
11394 {
11398 else
11401 }
11403 return
11406 }
11407 }
11413 /* Fold &a[i] - &a[j] to i-j. */
11418 {
11422 code
11426 }
11428 /* Further transformations are not for pointers. */
11432 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
11435 /* If arg0 is e.g. unsigned int and type is int, then this could
11436 introduce UB, because if A is INT_MIN at runtime, the original
11437 expression can be well defined while the latter is not.
11438 See PR83269. */
11447 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
11448 __complex__ ( x, -y ). This is not the same for SNaNs or if
11449 signed zeros are involved. */
11453 {
11460 {
11464 {
11466 arg1r ? arg1r
11471 }
11473 {
11477 arg1i ? arg1i
11480 }
11481 }
11482 }
11484 /* A - B -> A + (-B) if B is easily negatable. */
11488 /* Avoid this transformation if B is a positive REAL_CST. */
11496 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
11497 one. Make sure the type is not saturating and has the signedness of
11498 the stripped operands, as fold_plusminus_mult_expr will re-associate.
11499 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
11506 {
11510 }
11516 {
11517 /* Transform x * -C into -x * C if x is easily negatable. */
11532 {
11535 "occur when simplifying "
11537 WARN_STRICT_OVERFLOW_MISC);
11539 }
11541 /* Optimize z * conj(z) for integer complex numbers. */
11548 }
11549 else
11550 {
11551 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11552 This is not the same for NaNs or if signed zeros are
11553 involved. */
11559 {
11562 return
11568 return
11573 }
11575 /* Optimize z * conj(z) for floating point complex numbers.
11576 Guarded by flag_unsafe_math_optimizations as non-finite
11577 imaginary components don't produce scalar results. */
11586 }
11590 /* Canonicalize (X & C1) | C2. */
11594 {
11599 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11607 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11609 {
11612 }
11614 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11615 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11616 mode which allows further optimizations. */
11621 {
11626 {
11629 }
11630 }
11633 {
11638 }
11639 }
11641 /* See if this can be simplified into a rotate first. If that
11642 is unsuccessful continue in the association code. */
11646 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11654 /* See if this can be simplified into a rotate first. If that
11655 is unsuccessful continue in the association code. */
11659 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11664 {
11665 tree tem2;
11672 }
11673 /* Fold ~X & 1 as (X & 1) == 0. */
11677 {
11678 tree tem2;
11685 }
11686 /* Fold !X & 1 as X == 0. */
11689 {
11693 }
11695 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11696 multiple of 1 << CST. */
11698 {
11705 }
11707 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11708 bits from CST2. */
11712 {
11714 wide_int masked
11721 {
11722 /* Avoid the transform if arg1 is a mask of some
11723 mode which allows further optimizations. */
11730 }
11731 }
11733 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11736 {
11741 return
11743 }
11748 /* Don't touch a floating-point divide by zero unless the mode
11749 of the constant can represent infinity. */
11755 /* (-A) / (-B) -> A / B */
11767 /* Fall through */
11770 /* Simplify A / (B << N) where A and B are positive and B is
11771 a power of 2, to A >> (N + log2(B)). */
11776 {
11779 {
11787 WARN_STRICT_OVERFLOW_MISC);
11793 }
11794 }
11796 /* Fall through */
11804 /* Convert -A / -B to A / B when the type is signed and overflow is
11805 undefined. */
11809 {
11812 "when distributing negation across "
11814 WARN_STRICT_OVERFLOW_MISC);
11819 }
11823 {
11826 "when distributing negation across "
11828 WARN_STRICT_OVERFLOW_MISC);
11833 }
11835 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11836 operation, EXACT_DIV_EXPR.
11838 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11839 At one time others generated faster code, it's not clear if they do
11840 after the last round to changes to the DIV code in expmed.c. */
11851 {
11855 WARN_STRICT_OVERFLOW_MISC);
11857 }
11869 {
11873 WARN_STRICT_OVERFLOW_MISC);
11875 }
11883 /* Since negative shift count is not well-defined,
11884 don't try to compute it in the compiler. */
11890 /* If we have a rotate of a bit operation with the rotate count and
11891 the second operand of the bit operation both constant,
11892 permute the two operations. */
11898 {
11906 }
11908 /* Two consecutive rotates adding up to the some integer
11909 multiple of the precision of the type can be ignored. */
11925 /* Note that the operands of this must be ints
11926 and their values must be 0 or 1.
11927 ("true" is a fixed value perhaps depending on the language.) */
11928 /* If first arg is constant zero, return it. */
11931 /* FALLTHRU */
11933 /* If either arg is constant true, drop it. */
11937 /* Preserve sequence points. */
11940 /* If second arg is constant zero, result is zero, but first arg
11941 must be evaluated. */
11944 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11945 case will be handled here. */
11949 /* !X && X is always false. */
11953 /* X && !X is always false. */
11958 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
11959 means A >= Y && A != MAX, but in this case we know that
11960 A < X <= MAX. */
11964 {
11972 }
11981 /* Note that the operands of this must be ints
11982 and their values must be 0 or true.
11983 ("true" is a fixed value perhaps depending on the language.) */
11984 /* If first arg is constant true, return it. */
11987 /* FALLTHRU */
11989 /* If either arg is constant zero, drop it. */
11993 /* Preserve sequence points. */
11996 /* If second arg is constant true, result is true, but we must
11997 evaluate first arg. */
12000 /* Likewise for first arg, but note this only occurs here for
12001 TRUTH_OR_EXPR. */
12005 /* !X || X is always true. */
12009 /* X || !X is always true. */
12014 /* (X && !Y) || (!X && Y) is X ^ Y */
12017 {
12034 }
12043 /* If the second arg is constant zero, drop it. */
12046 /* If the second arg is constant true, this is a logical inversion. */
12048 {
12051 }
12052 /* Identical arguments cancel to zero. */
12056 /* !X ^ X is always true. */
12061 /* X ^ !X is always true. */
12077 /* bool_var != 1 becomes !bool_var. */
12084 /* bool_var == 0 becomes !bool_var. */
12091 /* !exp != 0 becomes !exp */
12096 /* If this is an EQ or NE comparison with zero and ARG0 is
12097 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12098 two operations, but the latter can be done in one less insn
12099 on machines that have only two-operand insns or on which a
12100 constant cannot be the first operand. */
12103 {
12108 {
12116 }
12119 {
12127 }
12128 }
12130 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12131 C1 is a valid shift constant, and C2 is a power of two, i.e.
12132 a single bit. */
12136 {
12141 {
12146 /* Check for a valid shift count. */
12148 {
12152 /* If (C2 << C1) doesn't overflow, then
12153 ((X >> C1) & C2) != 0 can be rewritten as
12154 (X & (C2 << C1)) != 0. */
12156 {
12163 }
12164 /* Otherwise, for signed (arithmetic) shifts,
12165 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12166 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12172 /* Otherwise, of unsigned (logical) shifts,
12173 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12174 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12175 else
12179 arg000);
12180 }
12181 }
12182 }
12184 /* If this is a comparison of a field, we may be able to simplify it. */
12187 /* Handle the constant case even without -O
12188 to make sure the warnings are given. */
12190 {
12194 }
12196 /* Optimize comparisons of strlen vs zero to a compare of the
12197 first character of the string vs zero. To wit,
12198 strlen(ptr) == 0 => *ptr == 0
12199 strlen(ptr) != 0 => *ptr != 0
12200 Other cases should reduce to one of these two (or a constant)
12201 due to the return value of strlen being unsigned. */
12203 {
12211 {
12212 tree ptrtype
12214 TYPE_QUAL_CONST));
12220 }
12221 }
12223 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12224 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12228 {
12233 {
12235 {
12238 }
12241 }
12242 }
12244 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12245 (X & C) == 0 when C is a single bit. */
12250 {
12257 arg1));
12258 }
12260 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12261 constant C is a power of two, i.e. a single bit. */
12268 {
12272 }
12274 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12275 when is C is a power of two, i.e. a single bit. */
12282 {
12288 }
12292 {
12295 }
12299 {
12306 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12307 operand_equal_p guarantees no side-effects so we don't need
12308 to use omit_one_operand on Z. */
12312 arg10));
12316 arg11));
12320 arg10));
12324 arg11));
12326 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12329 {
12335 }
12336 }
12338 /* Attempt to simplify equality/inequality comparisons of complex
12339 values. Only lower the comparison if the result is known or
12340 can be simplified to a single scalar comparison. */
12345 {
12350 {
12353 }
12354 else
12355 {
12358 }
12361 {
12364 }
12365 else
12366 {
12369 }
12373 {
12375 {
12380 }
12381 else
12382 {
12387 }
12388 }
12392 {
12394 {
12399 }
12400 else
12401 {
12406 }
12407 }
12408 }
12420 /* Transform comparisons of the form X +- C CMP X. */
12425 {
12430 /* (X - c) > X becomes false. */
12436 /* Likewise (X + c) < X becomes false. */
12442 /* Convert (X - c) <= X to true. */
12449 /* Convert (X + c) >= X to true. */
12455 }
12457 /* If we are comparing an ABS_EXPR with a constant, we can
12458 convert all the cases into explicit comparisons, but they may
12459 well not be faster than doing the ABS and one comparison.
12460 But ABS (X) <= C is a range comparison, which becomes a subtraction
12461 and a comparison, and is probably faster. */
12475 /* Convert ABS_EXPR<x> >= 0 to true. */
12482 {
12485 "when simplifying comparison of "
12487 WARN_STRICT_OVERFLOW_CONDITIONAL);
12490 arg0);
12491 }
12493 /* Convert ABS_EXPR<x> < 0 to false. */
12498 {
12501 "when simplifying comparison of "
12503 WARN_STRICT_OVERFLOW_CONDITIONAL);
12506 arg0);
12507 }
12509 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12510 and similarly for >= into !=. */
12520 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
12521 otherwise Y might be >= # of bits in X's type and thus e.g.
12522 (unsigned char) (1 << Y) for Y 15 might be 0.
12523 If the cast is widening, then 1 << Y should have unsigned type,
12524 otherwise if Y is number of bits in the signed shift type minus 1,
12525 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
12526 31 might be 0xffffffff80000000. */
12539 {
12545 }
12557 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12558 {
12570 }
12575 /* When pedantic, a compound expression can be neither an lvalue
12576 nor an integer constant expression. */
12579 /* Don't let (0, 0) be null pointer constant. */
12585 /* An ASSERT_EXPR should never be passed to fold_binary. */
12591 }
12593 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
12594 ((A & N) + B) & M -> (A + B) & M
12595 Similarly if (N & M) == 0,
12596 ((A | N) + B) & M -> (A + B) & M
12597 and for - instead of + (or unary - instead of +)
12598 and/or ^ instead of |.
12599 If B is constant and (B & M) == 0, fold into A & M.
12601 This function is a helper for match.pd patterns. Return non-NULL
12602 type in which the simplified operation should be performed only
12603 if any optimization is possible.
12605 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
12606 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
12607 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
12608 +/-. */
12609 tree
12614 {
12629 wide_int cst0;
12631 /* Now we know that arg0 is (C + D) or (C - D) or -C and
12632 arg1 (M) is == (1LL << cst) - 1.
12633 Store C into PMOP[0] and D into PMOP[1]. */
12640 {
12647 {
12650 }
12653 /* If C or D is of the form (A & N) where
12654 (N & M) == M, or of the form (A | N) or
12655 (A ^ N) where (N & M) == 0, replace it with A. */
12661 /* If C or D is a N where (N & M) == 0, it can be
12662 omitted (replaced with 0). */
12667 /* Similarly, with C - N where (-N & M) == 0. */
12675 }
12677 /* Only build anything new if we optimized one or both arguments above. */
12683 else
12685 }
12687 /* Used by contains_label_[p1]. */
12689 struct contains_label_data
12690 {
12693 };
12695 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
12696 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
12697 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
12699 static tree
12701 {
12704 {
12715 {
12723 }
12732 }
12733 }
12735 /* Return whether the sub-tree ST contains a label which is accessible from
12736 outside the sub-tree. */
12738 static bool
12740 {
12744 }
12746 /* Fold a ternary expression of code CODE and type TYPE with operands
12747 OP0, OP1, and OP2. Return the folded expression if folding is
12748 successful. Otherwise, return NULL_TREE. */
12750 tree
12753 {
12754 tree tem;
12761 /* If this is a commutative operation, and OP0 is a constant, move it
12762 to OP1 to reduce the number of tests below. */
12771 /* Strip any conversions that don't change the mode. This is safe
12772 for every expression, except for a comparison expression because
12773 its signedness is derived from its operands. So, in the latter
12774 case, only strip conversions that don't change the signedness.
12776 Note that this is done as an internal manipulation within the
12777 constant folder, in order to find the simplest representation of
12778 the arguments so that their form can be studied. In any cases,
12779 the appropriate type conversions should be put back in the tree
12780 that will get out of the constant folder. */
12782 {
12785 }
12788 {
12791 }
12794 {
12797 }
12800 {
12804 {
12810 }
12815 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12816 so all simple results must be passed through pedantic_non_lvalue. */
12818 {
12821 /* Only optimize constant conditions when the selected branch
12822 has the same type as the COND_EXPR. This avoids optimizing
12823 away "c ? x : throw", where the throw has a void type.
12824 Avoid throwing away that operand which contains label. */
12831 }
12833 {
12840 {
12843 {
12851 }
12856 }
12857 }
12859 /* If we have A op B ? A : C, we may be able to convert this to a
12860 simpler expression, depending on the operation and the values
12861 of B and C. Signed zeros prevent all of these transformations,
12862 for reasons given above each one.
12864 Also try swapping the arguments and inverting the conditional. */
12868 {
12875 }
12880 {
12887 arg00,
12888 arg01,
12892 }
12894 /* If the second operand is simpler than the third, swap them
12895 since that produces better jump optimization results. */
12898 {
12900 /* See if this can be inverted. If it can't, possibly because
12901 it was a floating-point inequality comparison, don't do
12902 anything. */
12906 }
12908 /* Convert A ? 1 : 0 to simply A. */
12913 /* If we try to convert OP0 to our type, the
12914 call to fold will try to move the conversion inside
12915 a COND, which will recurse. In that case, the COND_EXPR
12916 is probably the best choice, so leave it alone. */
12920 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12921 over COND_EXPR in cases such as floating point comparisons. */
12930 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12935 {
12936 /* sign_bit_p looks through both zero and sign extensions,
12937 but for this optimization only sign extensions are
12938 usable. */
12941 {
12944 {
12947 }
12949 }
12950 /* sign_bit_p only checks ARG1 bits within A's precision.
12951 If <sign bit of A> has wider type than A, bits outside
12952 of A's precision in <sign bit of A> need to be checked.
12953 If they are all 0, this optimization needs to be done
12954 in unsigned A's type, if they are all 1 in signed A's type,
12955 otherwise this can't be done. */
12961 {
12963 tree tem_type;
12976 {
12979 }
12981 {
12984 }
12985 else
12987 }
12990 return
12996 arg1)));
12997 }
12999 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13000 already handled above. */
13005 {
13015 op1);
13016 }
13018 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13019 is probably obsolete because the first operand should be a
13020 truth value (that's why we have the two cases above), but let's
13021 leave it in until we can confirm this for all front-ends. */
13029 /* operand_equal_p compares just value, not precision, so e.g.
13030 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
13031 second operand 32-bit -128, which is not a power of two (or vice
13032 versa. */
13036 /* Disable the transformations below for vectors, since
13037 fold_binary_op_with_conditional_arg may undo them immediately,
13038 yielding an infinite loop. */
13042 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13051 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13056 {
13058 /* Only perform transformation if ARG0 is easily inverted. */
13062 ? BIT_IOR_EXPR
13065 op1);
13066 }
13068 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13073 {
13075 /* Only perform transformation if ARG0 is easily inverted. */
13081 op2);
13082 }
13084 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13096 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13097 of fold_ternary on them. */
13107 {
13109 unsigned HOST_WIDE_INT width
13120 {
13125 {
13127 {
13132 }
13138 }
13139 }
13140 }
13142 /* On constants we can use native encode/interpret to constant
13143 fold (nearly) all BIT_FIELD_REFs. */
13149 {
13152 /* Limit us to a reasonable amount of work. To relax the
13153 other limitations we need bit-shifting of the buffer
13154 and rounding up the size. */
13158 {
13160 unsigned HOST_WIDE_INT len
13165 {
13170 }
13171 }
13172 }
13177 /* Perform constant folding of BIT_INSERT_EXPR. */
13181 {
13182 /* Build a vector of integers from the tree mask. */
13183 vec_perm_builder builder;
13187 /* Create a vec_perm_indices for the integer vector. */
13192 }
13196 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
13199 {
13205 wide_int tem2
13209 }
13214 {
13216 unsigned HOST_WIDE_INT elsize
13219 {
13225 {
13231 }
13232 }
13233 }
13239 }
13241 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
13242 of an array (or vector). *CTOR_IDX if non-NULL is updated with the
13243 constructor element index of the value returned. If the element is
13244 not found NULL_TREE is returned and *CTOR_IDX is updated to
13245 the index of the element after the ACCESS_INDEX position (which
13246 may be outside of the CTOR array). */
13248 tree
13251 {
13257 {
13260 {
13261 /* Static constructors for variably sized objects makes no sense. */
13264 /* ??? When it is obvious that the range is signed, treat it so. */
13269 {
13271 low_bound
13273 SIGNED);
13274 }
13275 else
13276 {
13279 }
13280 }
13281 }
13285 index_sgn);
13297 {
13298 /* Array constructor might explicitly set index, or specify a range,
13299 or leave index NULL meaning that it is next index after previous
13300 one. */
13302 {
13304 max_index = index
13306 else
13307 {
13310 index_sgn);
13311 max_index
13313 index_sgn);
13315 }
13316 }
13318 {
13324 }
13325 else
13328 /* Do we have match? */
13330 {
13332 {
13336 }
13337 }
13339 /* We're past the element we search for. Note during parsing
13340 the elements might not be sorted.
13341 ??? We should use a binary search and a flag on the
13342 CONSTRUCTOR as to whether elements are sorted in declaration
13343 order. */
13345 }
13349 }
13351 /* Perform constant folding and related simplification of EXPR.
13352 The related simplifications include x*1 => x, x*0 => 0, etc.,
13353 and application of the associative law.
13354 NOP_EXPR conversions may be removed freely (as long as we
13355 are careful not to change the type of the overall expression).
13356 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13357 but we can constant-fold them if they have constant operands. */
13359 #ifdef ENABLE_FOLD_CHECKING
13360 # define fold(x) fold_1 (x)
13362 static
13363 #endif
13364 tree
13366 {
13370 tree tem;
13373 /* Return right away if a constant. */
13377 /* CALL_EXPR-like objects with variable numbers of operands are
13378 treated specially. */
13380 {
13382 {
13385 }
13387 }
13390 {
13395 {
13413 }
13414 }
13417 {
13419 {
13426 {
13431 }
13434 }
13436 /* Return a VECTOR_CST if possible. */
13438 {
13444 tree val;
13450 }
13458 }
13460 #ifdef ENABLE_FOLD_CHECKING
13461 #undef fold
13468 /* When --enable-checking=fold, compute a digest of expr before
13469 and after actual fold call to see if fold did not accidentally
13470 change original expr. */
13472 tree
13474 {
13475 tree ret;
13495 }
13497 void
13499 {
13510 }
13512 static void
13514 {
13516 }
13518 static void
13521 {
13527 recursive_label:
13537 {
13538 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
13546 }
13554 {
13555 /* Allow these fields to be modified. */
13556 tree tmp;
13567 {
13570 }
13571 }
13573 {
13574 /* Allow the no-warning bit to be set. Perhaps we shouldn't allow
13575 that and change builtins.c etc. instead - see PR89543. */
13581 }
13592 {
13595 {
13611 }
13615 {
13628 }
13645 {
13651 }
13654 {
13656 {
13659 }
13661 }
13672 {
13675 }
13685 }
13686 }
13688 /* Helper function for outputting the checksum of a tree T. When
13689 debugging with gdb, you can "define mynext" to be "next" followed
13690 by "call debug_fold_checksum (op0)", then just trace down till the
13691 outputs differ. */
13693 DEBUG_FUNCTION void
13695 {
13710 }
13712 #endif
13714 /* Fold a unary tree expression with code CODE of type TYPE with an
13715 operand OP0. LOC is the location of the resulting expression.
13716 Return a folded expression if successful. Otherwise, return a tree
13717 expression with code CODE of type TYPE with an operand OP0. */
13719 tree
13722 {
13723 tree tem;
13724 #ifdef ENABLE_FOLD_CHECKING
13733 #endif
13739 #ifdef ENABLE_FOLD_CHECKING
13746 #endif
13748 }
13750 /* Fold a binary tree expression with code CODE of type TYPE with
13751 operands OP0 and OP1. LOC is the location of the resulting
13752 expression. Return a folded expression if successful. Otherwise,
13753 return a tree expression with code CODE of type TYPE with operands
13754 OP0 and OP1. */
13756 tree
13759 MEM_STAT_DECL)
13760 {
13761 tree tem;
13762 #ifdef ENABLE_FOLD_CHECKING
13779 #endif
13785 #ifdef ENABLE_FOLD_CHECKING
13800 #endif
13802 }
13804 /* Fold a ternary tree expression with code CODE of type TYPE with
13805 operands OP0, OP1, and OP2. Return a folded expression if
13806 successful. Otherwise, return a tree expression with code CODE of
13807 type TYPE with operands OP0, OP1, and OP2. */
13809 tree
13812 {
13813 tree tem;
13814 #ifdef ENABLE_FOLD_CHECKING
13838 #endif
13845 #ifdef ENABLE_FOLD_CHECKING
13868 #endif
13870 }
13872 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
13873 arguments in ARGARRAY, and a null static chain.
13874 Return a folded expression if successful. Otherwise, return a CALL_EXPR
13875 of type TYPE from the given operands as constructed by build_call_array. */
13877 tree
13880 {
13881 tree tem;
13882 #ifdef ENABLE_FOLD_CHECKING
13901 #endif
13907 #ifdef ENABLE_FOLD_CHECKING
13923 #endif
13925 }
13927 /* Perform constant folding and related simplification of initializer
13928 expression EXPR. These behave identically to "fold_buildN" but ignore
13929 potential run-time traps and exceptions that fold must preserve. */
13931 #define START_FOLD_INIT \
13932 int saved_signaling_nans = flag_signaling_nans;\
13933 int saved_trapping_math = flag_trapping_math;\
13934 int saved_rounding_math = flag_rounding_math;\
13935 int saved_trapv = flag_trapv;\
13936 int saved_folding_initializer = folding_initializer;\
13937 flag_signaling_nans = 0;\
13938 flag_trapping_math = 0;\
13939 flag_rounding_math = 0;\
13940 flag_trapv = 0;\
13941 folding_initializer = 1;
13943 #define END_FOLD_INIT \
13944 flag_signaling_nans = saved_signaling_nans;\
13945 flag_trapping_math = saved_trapping_math;\
13946 flag_rounding_math = saved_rounding_math;\
13947 flag_trapv = saved_trapv;\
13948 folding_initializer = saved_folding_initializer;
13950 tree
13952 {
13953 tree result;
13954 START_FOLD_INIT;
13958 END_FOLD_INIT;
13960 }
13962 tree
13965 {
13966 tree result;
13967 START_FOLD_INIT;
13971 END_FOLD_INIT;
13973 }
13975 tree
13978 {
13979 tree result;
13980 START_FOLD_INIT;
13984 END_FOLD_INIT;
13986 }
13988 tree
13991 {
13992 tree result;
13993 START_FOLD_INIT;
13997 END_FOLD_INIT;
13999 }
14001 tree
14004 {
14005 tree result;
14006 START_FOLD_INIT;
14010 END_FOLD_INIT;
14012 }
14014 #undef START_FOLD_INIT
14015 #undef END_FOLD_INIT
14017 /* Determine if first argument is a multiple of second argument. Return 0 if
14018 it is not, or we cannot easily determined it to be.
14020 An example of the sort of thing we care about (at this point; this routine
14021 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14022 fold cases do now) is discovering that
14024 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14026 is a multiple of
14028 SAVE_EXPR (J * 8)
14030 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14032 This code also handles discovering that
14034 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14036 is a multiple of 8 so we don't have to worry about dealing with a
14037 possible remainder.
14039 Note that we *look* inside a SAVE_EXPR only to determine how it was
14040 calculated; it is not safe for fold to do much of anything else with the
14041 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14042 at run time. For example, the latter example above *cannot* be implemented
14043 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14044 evaluation time of the original SAVE_EXPR is not necessarily the same at
14045 the time the new expression is evaluated. The only optimization of this
14046 sort that would be valid is changing
14048 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14050 divided by 8 to
14052 SAVE_EXPR (I) * SAVE_EXPR (J)
14054 (where the same SAVE_EXPR (J) is used in the original and the
14055 transformed version). */
14057 int
14059 {
14070 {
14072 /* Bitwise and provides a power of two multiple. If the mask is
14073 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14081 {
14087 {
14090 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
14092 {
14096 {
14099 }
14100 }
14102 }
14103 }
14108 /* It is impossible to prove if op0 - op1 is multiple of bottom
14109 precisely, so be conservative here checking if both op0 and op1
14110 are multiple of bottom. Note we check the second operand first
14111 since it's usually simpler. */
14116 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
14117 as op0 - 3 if the expression has unsigned type. For example,
14118 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
14128 {
14130 /* const_binop may not detect overflow correctly,
14131 so check for it explicitly here. */
14139 }
14143 /* Can't handle conversions from non-integral or wider integral type. */
14149 /* fall through */
14166 SIGNED);
14172 {
14175 /* Check for special cases to see if top is defined as multiple
14176 of bottom:
14178 top = (X & ~(bottom - 1) ; bottom is power of 2
14180 or
14182 Y = X % bottom
14183 top = X - Y. */
14202 }
14204 /* fall through */
14212 }
14213 }
14215 /* Return true if expression X cannot be (or contain) a NaN or infinity.
14216 This function returns true for integer expressions, and returns
14217 false if uncertain. */
14219 bool
14221 {
14226 {
14249 {
14250 CASE_CFN_FABS:
14252 CASE_CFN_FMAX:
14253 CASE_CFN_FMIN:
14258 }
14262 }
14263 }
14265 /* Return true if expression X evaluates to an infinity.
14266 This function returns false for integer expressions. */
14268 bool
14270 {
14274 {
14287 }
14288 }
14290 /* Return true if expression X could evaluate to an infinity.
14291 This function returns false for integer expressions, and returns
14292 true if uncertain. */
14294 bool
14296 {
14300 {
14313 }
14314 }
14316 /* Return true if expression X evaluates to a signaling NaN.
14317 This function returns false for integer expressions. */
14319 bool
14321 {
14325 {
14336 }
14337 }
14339 /* Return true if expression X could evaluate to a signaling NaN.
14340 This function returns false for integer expressions, and returns
14341 true if uncertain. */
14343 bool
14345 {
14349 {
14369 {
14370 CASE_CFN_FABS:
14372 CASE_CFN_FMAX:
14373 CASE_CFN_FMIN:
14378 }
14381 }
14382 }
14384 /* Return true if expression X evaluates to a NaN.
14385 This function returns false for integer expressions. */
14387 bool
14389 {
14393 {
14404 }
14405 }
14407 /* Return true if expression X could evaluate to a NaN.
14408 This function returns false for integer expressions, and returns
14409 true if uncertain. */
14411 bool
14413 {
14417 {
14442 {
14443 CASE_CFN_FABS:
14445 CASE_CFN_FMAX:
14446 CASE_CFN_FMIN:
14451 }
14454 }
14455 }
14457 /* Return true if expression X could evaluate to -0.0.
14458 This function returns true if uncertain. */
14460 bool
14462 {
14466 {
14481 {
14482 CASE_CFN_FABS:
14486 }
14489 }
14490 /* Ideally !(tree_expr_nonzero_p (X) || tree_expr_nonnegative_p (X))
14491 * but currently those predicates require tree and not const_tree. */
14493 }
14495 #define tree_expr_nonnegative_warnv_p(X, Y) \
14498 #define RECURSE(X) \
14499 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
14501 /* Return true if CODE or TYPE is known to be non-negative. */
14503 static bool
14505 {
14508 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14509 have a signed:1 type (where the value is -1 and 0). */
14512 }
14514 /* Return true if (CODE OP0) is known to be non-negative. If the return
14515 value is based on the assumption that signed overflow is undefined,
14516 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14517 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14519 bool
14522 {
14527 {
14529 /* We can't return 1 if flag_wrapv is set because
14530 ABS_EXPR<INT_MIN> = INT_MIN. */
14534 {
14537 }
14545 CASE_CONVERT:
14546 {
14551 {
14555 {
14559 }
14560 }
14562 {
14568 }
14569 }
14574 }
14576 /* We don't know sign of `t', so be conservative and return false. */
14578 }
14580 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14581 value is based on the assumption that signed overflow is undefined,
14582 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14583 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14585 bool
14589 {
14594 {
14600 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14601 both unsigned and at least 2 bits shorter than the result. */
14605 {
14610 {
14614 }
14615 }
14620 {
14621 /* x * x is always non-negative for floating point x
14622 or without overflow. */
14625 {
14630 }
14631 }
14633 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14634 both unsigned and their total bits is shorter than the result. */
14638 {
14657 {
14667 }
14668 }
14675 /* Usually RECURSE (op0) || RECURSE (op1) but NaNs complicate
14676 things. */
14701 }
14703 /* We don't know sign of `t', so be conservative and return false. */
14705 }
14707 /* Return true if T is known to be non-negative. If the return
14708 value is based on the assumption that signed overflow is undefined,
14709 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14710 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14712 bool
14714 {
14719 {
14733 /* Limit the depth of recursion to avoid quadratic behavior.
14734 This is expected to catch almost all occurrences in practice.
14735 If this code misses important cases that unbounded recursion
14736 would not, passes that need this information could be revised
14737 to provide it through dataflow propagation. */
14745 }
14746 }
14748 /* Return true if T is known to be non-negative. If the return
14749 value is based on the assumption that signed overflow is undefined,
14750 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14751 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14753 bool
14756 {
14758 {
14759 CASE_CFN_ACOS:
14760 CASE_CFN_ACOSH:
14761 CASE_CFN_CABS:
14762 CASE_CFN_COSH:
14763 CASE_CFN_ERFC:
14764 CASE_CFN_EXP:
14765 CASE_CFN_EXP10:
14766 CASE_CFN_EXP2:
14767 CASE_CFN_FABS:
14768 CASE_CFN_FDIM:
14769 CASE_CFN_HYPOT:
14770 CASE_CFN_POW10:
14771 CASE_CFN_FFS:
14772 CASE_CFN_PARITY:
14773 CASE_CFN_POPCOUNT:
14774 CASE_CFN_CLZ:
14775 CASE_CFN_CLRSB:
14780 /* Always true. */
14783 CASE_CFN_SQRT:
14784 CASE_CFN_SQRT_FN:
14785 /* sqrt(-0.0) is -0.0. */
14790 CASE_CFN_ASINH:
14791 CASE_CFN_ATAN:
14792 CASE_CFN_ATANH:
14793 CASE_CFN_CBRT:
14794 CASE_CFN_CEIL:
14795 CASE_CFN_CEIL_FN:
14796 CASE_CFN_ERF:
14797 CASE_CFN_EXPM1:
14798 CASE_CFN_FLOOR:
14799 CASE_CFN_FLOOR_FN:
14800 CASE_CFN_FMOD:
14801 CASE_CFN_FREXP:
14802 CASE_CFN_ICEIL:
14803 CASE_CFN_IFLOOR:
14804 CASE_CFN_IRINT:
14805 CASE_CFN_IROUND:
14806 CASE_CFN_LCEIL:
14807 CASE_CFN_LDEXP:
14808 CASE_CFN_LFLOOR:
14809 CASE_CFN_LLCEIL:
14810 CASE_CFN_LLFLOOR:
14811 CASE_CFN_LLRINT:
14812 CASE_CFN_LLROUND:
14813 CASE_CFN_LRINT:
14814 CASE_CFN_LROUND:
14815 CASE_CFN_MODF:
14816 CASE_CFN_NEARBYINT:
14817 CASE_CFN_NEARBYINT_FN:
14818 CASE_CFN_RINT:
14819 CASE_CFN_RINT_FN:
14820 CASE_CFN_ROUND:
14821 CASE_CFN_ROUND_FN:
14822 CASE_CFN_ROUNDEVEN:
14823 CASE_CFN_ROUNDEVEN_FN:
14824 CASE_CFN_SCALB:
14825 CASE_CFN_SCALBLN:
14826 CASE_CFN_SCALBN:
14827 CASE_CFN_SIGNBIT:
14828 CASE_CFN_SIGNIFICAND:
14829 CASE_CFN_SINH:
14830 CASE_CFN_TANH:
14831 CASE_CFN_TRUNC:
14832 CASE_CFN_TRUNC_FN:
14833 /* True if the 1st argument is nonnegative. */
14836 CASE_CFN_FMAX:
14837 CASE_CFN_FMAX_FN:
14838 /* Usually RECURSE (arg0) || RECURSE (arg1) but NaNs complicate
14839 things. In the presence of sNaNs, we're only guaranteed to be
14840 non-negative if both operands are non-negative. In the presence
14841 of qNaNs, we're non-negative if either operand is non-negative
14842 and can't be a qNaN, or if both operands are non-negative. */
14851 CASE_CFN_FMIN:
14852 CASE_CFN_FMIN_FN:
14853 /* True if the 1st AND 2nd arguments are nonnegative. */
14856 CASE_CFN_COPYSIGN:
14857 CASE_CFN_COPYSIGN_FN:
14858 /* True if the 2nd argument is nonnegative. */
14861 CASE_CFN_POWI:
14862 /* True if the 1st argument is nonnegative or the second
14863 argument is an even integer. */
14869 CASE_CFN_POW:
14870 /* True if the 1st argument is nonnegative or the second
14871 argument is an even integer valued real. */
14873 {
14874 REAL_VALUE_TYPE c;
14875 HOST_WIDE_INT n;
14880 {
14881 REAL_VALUE_TYPE cint;
14885 }
14886 }
14891 }
14893 }
14895 /* Return true if T is known to be non-negative. If the return
14896 value is based on the assumption that signed overflow is undefined,
14897 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14898 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14900 static bool
14902 {
14908 {
14910 {
14914 /* If the initializer is non-void, then it's a normal expression
14915 that will be assigned to the slot. */
14919 /* Otherwise, the initializer sets the slot in some way. One common
14920 way is an assignment statement at the end of the initializer. */
14922 {
14930 else
14932 }
14938 }
14941 {
14947 arg0,
14948 arg1,
14950 }
14963 }
14964 }
14966 #undef RECURSE
14967 #undef tree_expr_nonnegative_warnv_p
14969 /* Return true if T is known to be non-negative. If the return
14970 value is based on the assumption that signed overflow is undefined,
14971 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14972 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14974 bool
14976 {
14983 {
15005 }
15008 {
15034 }
15035 }
15037 /* Return true if `t' is known to be non-negative. Handle warnings
15038 about undefined signed overflow. */
15040 bool
15042 {
15049 "determining that expression is always "
15051 WARN_STRICT_OVERFLOW_MISC);
15053 }
15056 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15057 For floating point we further ensure that T is not denormal.
15058 Similar logic is present in nonzero_address in rtlanal.h.
15060 If the return value is based on the assumption that signed overflow
15061 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15062 change *STRICT_OVERFLOW_P. */
15064 bool
15067 {
15069 {
15072 strict_overflow_p);
15075 {
15081 strict_overflow_p));
15082 }
15087 strict_overflow_p);
15091 }
15094 }
15096 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15097 For floating point we further ensure that T is not denormal.
15098 Similar logic is present in nonzero_address in rtlanal.h.
15100 If the return value is based on the assumption that signed overflow
15101 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15102 change *STRICT_OVERFLOW_P. */
15104 bool
15106 tree type,
15107 tree op0,
15109 {
15112 {
15116 {
15117 /* With the presence of negative values it is hard
15118 to say something. */
15125 /* One of operands must be positive and the other non-negative. */
15126 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15127 overflows, on a twos-complement machine the sum of two
15128 nonnegative numbers can never be zero. */
15130 strict_overflow_p)
15132 strict_overflow_p));
15133 }
15138 {
15140 strict_overflow_p)
15142 strict_overflow_p))
15143 {
15146 }
15147 }
15156 {
15159 }
15166 {
15170 /* When both operands are nonzero, then MAX must be too. */
15172 strict_overflow_p))
15175 /* MAX where operand 0 is positive is positive. */
15177 strict_overflow_p);
15178 }
15179 /* MAX where operand 1 is positive is positive. */
15184 {
15188 }
15193 strict_overflow_p)
15195 strict_overflow_p));
15199 }
15202 }
15204 /* Return true when T is an address and is known to be nonzero.
15205 For floating point we further ensure that T is not denormal.
15206 Similar logic is present in nonzero_address in rtlanal.h.
15208 If the return value is based on the assumption that signed overflow
15209 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15210 change *STRICT_OVERFLOW_P. */
15212 bool
15214 {
15217 {
15222 {
15234 /* For objects in symbol table check if we know they are non-zero.
15235 Don't do anything for variables and functions before symtab is built;
15236 it is quite possible that they will be declared weak later. */
15241 /* Constants are never weak. */
15246 }
15254 {
15258 }
15268 }
15270 }
15272 #define integer_valued_real_p(X) \
15275 #define RECURSE(X) \
15276 ((integer_valued_real_p) (X, depth + 1))
15278 /* Return true if the floating point result of (CODE OP0) has an
15279 integer value. We also allow +Inf, -Inf and NaN to be considered
15280 integer values. Return false for signaling NaN.
15282 DEPTH is the current nesting depth of the query. */
15284 bool
15286 {
15288 {
15295 CASE_CONVERT:
15296 {
15303 }
15307 }
15309 }
15311 /* Return true if the floating point result of (CODE OP0 OP1) has an
15312 integer value. We also allow +Inf, -Inf and NaN to be considered
15313 integer values. Return false for signaling NaN.
15315 DEPTH is the current nesting depth of the query. */
15317 bool
15319 {
15321 {
15331 }
15333 }
15335 /* Return true if the floating point result of calling FNDECL with arguments
15336 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
15337 considered integer values. Return false for signaling NaN. If FNDECL
15338 takes fewer than 2 arguments, the remaining ARGn are null.
15340 DEPTH is the current nesting depth of the query. */
15342 bool
15344 {
15346 {
15347 CASE_CFN_CEIL:
15348 CASE_CFN_CEIL_FN:
15349 CASE_CFN_FLOOR:
15350 CASE_CFN_FLOOR_FN:
15351 CASE_CFN_NEARBYINT:
15352 CASE_CFN_NEARBYINT_FN:
15353 CASE_CFN_RINT:
15354 CASE_CFN_RINT_FN:
15355 CASE_CFN_ROUND:
15356 CASE_CFN_ROUND_FN:
15357 CASE_CFN_ROUNDEVEN:
15358 CASE_CFN_ROUNDEVEN_FN:
15359 CASE_CFN_TRUNC:
15360 CASE_CFN_TRUNC_FN:
15363 CASE_CFN_FMIN:
15364 CASE_CFN_FMIN_FN:
15365 CASE_CFN_FMAX:
15366 CASE_CFN_FMAX_FN:
15371 }
15373 }
15375 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
15376 has an integer value. We also allow +Inf, -Inf and NaN to be
15377 considered integer values. Return false for signaling NaN.
15379 DEPTH is the current nesting depth of the query. */
15381 bool
15383 {
15385 {
15393 /* Limit the depth of recursion to avoid quadratic behavior.
15394 This is expected to catch almost all occurrences in practice.
15395 If this code misses important cases that unbounded recursion
15396 would not, passes that need this information could be revised
15397 to provide it through dataflow propagation. */
15401 depth));
15405 }
15407 }
15409 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
15410 has an integer value. We also allow +Inf, -Inf and NaN to be
15411 considered integer values. Return false for signaling NaN.
15413 DEPTH is the current nesting depth of the query. */
15415 static bool
15417 {
15419 {
15430 }
15432 }
15434 #undef RECURSE
15435 #undef integer_valued_real_p
15437 /* Return true if the floating point expression T has an integer value.
15438 We also allow +Inf, -Inf and NaN to be considered integer values.
15439 Return false for signaling NaN.
15441 DEPTH is the current nesting depth of the query. */
15443 bool
15445 {
15453 {
15469 }
15472 {
15478 {
15487 }
15491 }
15492 }
15494 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15495 attempt to fold the expression to a constant without modifying TYPE,
15496 OP0 or OP1.
15498 If the expression could be simplified to a constant, then return
15499 the constant. If the expression would not be simplified to a
15500 constant, then return NULL_TREE. */
15502 tree
15504 {
15507 }
15509 /* Given the components of a unary expression CODE, TYPE and OP0,
15510 attempt to fold the expression to a constant without modifying
15511 TYPE or OP0.
15513 If the expression could be simplified to a constant, then return
15514 the constant. If the expression would not be simplified to a
15515 constant, then return NULL_TREE. */
15517 tree
15519 {
15522 }
15524 /* If EXP represents referencing an element in a constant string
15525 (either via pointer arithmetic or array indexing), return the
15526 tree representing the value accessed, otherwise return NULL. */
15528 tree
15530 {
15534 {
15536 tree index;
15537 tree string;
15542 else
15543 {
15547 /* Optimize the special-case of a zero lower bound.
15549 We convert the low_bound to sizetype to avoid some problems
15550 with constant folding. (E.g. suppose the lower bound is 1,
15551 and its mode is QI. Without the conversion,l (ARRAY
15552 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15553 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15559 }
15561 scalar_int_mode char_mode;
15573 }
15575 }
15577 /* Folds a read from vector element at IDX of vector ARG. */
15579 tree
15581 {
15586 {
15590 {
15597 }
15598 }
15600 }
15602 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15603 an integer constant, real, or fixed-point constant.
15605 TYPE is the type of the result. */
15607 static tree
15609 {
15613 {
15619 {
15620 FIXED_VALUE_TYPE f;
15625 /* Propagate overflow flags. */
15629 }
15633 {
15640 }
15643 }
15646 }
15648 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15649 an integer constant or real constant.
15651 TYPE is the type of the result. */
15653 tree
15655 {
15659 {
15661 {
15662 /* If the value is unsigned or non-negative, then the absolute value
15663 is the same as the ordinary value. */
15667 ;
15669 /* If the value is negative, then the absolute value is
15670 its negation. */
15671 else
15674 /* Force to the destination type, set TREE_OVERFLOW for signed
15675 TYPE only. */
15677 }
15683 else
15689 }
15692 }
15694 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15695 constant. TYPE is the type of the result. */
15697 static tree
15699 {
15703 }
15705 /* Given CODE, a relational operator, the target type, TYPE and two
15706 constant operands OP0 and OP1, return the result of the
15707 relational operation. If the result is not a compile time
15708 constant, then return NULL_TREE. */
15710 static tree
15712 {
15715 /* From here on, the only cases we handle are when the result is
15716 known to be a constant. */
15719 {
15723 /* Handle the cases where either operand is a NaN. */
15725 {
15727 {
15755 }
15758 }
15761 }
15764 {
15768 }
15770 /* Handle equality/inequality of complex constants. */
15772 {
15783 else
15785 }
15788 {
15790 {
15791 /* Have vector comparison with scalar boolean result. */
15799 {
15807 }
15809 }
15810 tree_vector_builder elts;
15815 {
15828 }
15831 }
15833 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15835 To compute GT, swap the arguments and do LT.
15836 To compute GE, do LT and invert the result.
15837 To compute LE, swap the arguments, do LT and invert the result.
15838 To compute NE, do EQ and invert the result.
15840 Therefore, the code below must handle only EQ and LT. */
15843 {
15846 }
15848 /* Note that it is safe to invert for real values here because we
15849 have already handled the one case that it matters. */
15853 {
15856 }
15858 /* Compute a result for LT or EQ if args permit;
15859 Otherwise return T. */
15861 {
15864 else
15866 }
15867 else
15873 }
15875 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15876 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15877 itself. */
15879 tree
15881 {
15882 /* If the expression does not have side effects then we don't have to wrap
15883 it with a cleanup point expression. */
15887 /* If the expression is a return, check to see if the expression inside the
15888 return has no side effects or the right hand side of the modify expression
15889 inside the return. If either don't have side effects set we don't need to
15890 wrap the expression in a cleanup point expression. Note we don't check the
15891 left hand side of the modify because it should always be a return decl. */
15893 {
15900 }
15903 }
15905 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15906 of an indirection through OP0, or NULL_TREE if no simplification is
15907 possible. */
15909 tree
15911 {
15913 tree subtype;
15914 poly_uint64 const_op01;
15923 {
15927 /* *&CONST_DECL -> to the value of the const decl. */
15930 /* *&p => p; make sure to handle *&"str"[cst] here. */
15932 {
15936 else
15938 }
15939 /* *(foo *)&fooarray => fooarray[0] */
15942 && (!in_gimple_form
15944 {
15954 }
15955 /* *(foo *)&complexfoo => __real__ complexfoo */
15959 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15962 {
15966 index);
15967 }
15968 }
15972 {
15978 {
15979 tree op00type;
15983 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15986 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
15987 but we want to treat offsets with MSB set as negative.
15988 For the code below negative offsets are invalid and
15989 TYPE_SIZE of the element is something unsigned, so
15990 check whether op01 fits into poly_int64, which implies
15991 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
15992 then just use poly_uint64 because we want to treat the
15993 value as unsigned. */
15995 {
15997 poly_uint64 max_offset
16001 {
16006 }
16007 }
16008 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16011 {
16013 const_op01))
16015 }
16016 /* ((foo *)&fooarray)[1] => fooarray[1] */
16019 {
16028 {
16033 }
16034 }
16035 }
16036 }
16038 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16041 && (!in_gimple_form
16043 {
16044 tree type_domain;
16054 NULL_TREE);
16055 }
16058 }
16060 /* Builds an expression for an indirection through T, simplifying some
16061 cases. */
16063 tree
16065 {
16073 }
16075 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16077 tree
16079 {
16084 else
16086 }
16088 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16089 whose result is ignored. The type of the returned tree need not be
16090 the same as the original expression. */
16092 tree
16094 {
16100 {
16111 else
16117 {
16133 }
16138 }
16139 }
16141 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16143 tree
16145 {
16151 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16152 have to do anything. Only do this when we are not given a const,
16153 because in that case, this check is more expensive than just
16154 doing it. */
16156 {
16161 }
16163 /* If divisor is a power of two, simplify this to bit manipulation. */
16165 {
16167 {
16181 }
16182 else
16183 {
16184 tree t;
16190 }
16191 }
16192 else
16193 {
16198 }
16201 }
16203 /* Likewise, but round down. */
16205 tree
16207 {
16214 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16215 have to do anything. Only do this when we are not given a const,
16216 because in that case, this check is more expensive than just
16217 doing it. */
16219 {
16224 }
16226 /* If divisor is a power of two, simplify this to bit manipulation. */
16228 {
16229 tree t;
16233 }
16234 else
16235 {
16240 }
16243 }
16245 /* Returns the pointer to the base of the object addressed by EXP and
16246 extracts the information about the offset of the access, storing it
16247 to PBITPOS and POFFSET. */
16249 static tree
16252 {
16253 tree core;
16254 machine_mode mode;
16256 poly_int64 bitsize;
16260 {
16265 }
16267 {
16273 {
16274 poly_offset_int tem
16280 }
16281 }
16282 else
16283 {
16287 }
16290 }
16292 /* Returns true if addresses of E1 and E2 differ by a constant, false
16293 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16295 bool
16297 {
16312 {
16322 }
16324 {
16325 /* If only one of the offsets is non-constant, the difference cannot
16326 be a constant. */
16328 }
16329 else
16334 }
16336 /* Return OFF converted to a pointer offset type suitable as offset for
16337 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16338 tree
16340 {
16344 }
16346 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16347 tree
16349 {
16352 }
16354 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16355 tree
16357 {
16360 }
16362 /* Return a pointer to a NUL-terminated string containing the sequence
16363 of bytes corresponding to the representation of the object referred to
16364 by SRC (or a subsequence of such bytes within it if SRC is a reference
16365 to an initialized constant array plus some constant offset).
16366 Set *STRSIZE the number of bytes in the constant sequence including
16367 the terminating NUL byte. *STRSIZE is equal to sizeof(A) - OFFSET
16368 where A is the array that stores the constant sequence that SRC points
16369 to and OFFSET is the byte offset of SRC from the beginning of A. SRC
16370 need not point to a string or even an array of characters but may point
16371 to an object of any type. */
16375 {
16376 /* The offset into the array A storing the string, and A's byte size. */
16377 tree offset_node;
16378 tree mem_size;
16385 else
16392 {
16395 else
16397 }
16402 /* ARRAY_SIZE is the byte size of the array the constant sequence
16403 is stored in and equal to sizeof A. INIT_BYTES is the number
16404 of bytes in the constant sequence used to initialize the array,
16405 including any embedded NULs as well as the terminating NUL (for
16406 strings), but not including any trailing zeros/NULs past
16407 the terminating one appended implicitly to a string literal to
16408 zero out the remainder of the array it's stored in. For example,
16409 given:
16410 const char a[7] = "abc\0d";
16411 n = strlen (a + 1);
16412 ARRAY_SIZE is 7, INIT_BYTES is 6, and OFFSET is 1. For a valid
16413 (i.e., nul-terminated) string with no embedded nuls, INIT_BYTES
16414 is equal to strlen (A) + 1. */
16419 /* Ideally this would turn into a gcc_checking_assert over time. */
16427 {
16428 /* Compute and store the number of characters from the beginning
16429 of the substring at OFFSET to the end, including the terminating
16430 nul. Offsets past the initial length refer to null strings. */
16433 else
16435 }
16436 else
16437 {
16439 /* Support only properly NUL-terminated single byte strings. */
16444 }
16447 }
16449 /* Return a pointer to a NUL-terminated string corresponding to
16450 the expression STR referencing a constant string, possibly
16451 involving a constant offset. Return null if STR either doesn't
16452 reference a constant string or if it involves a nonconstant
16453 offset. */
16457 {
16459 }
16461 /* Given a tree T, compute which bits in T may be nonzero. */
16463 wide_int
16465 {
16467 {
16485 CASE_CONVERT:
16491 {
16496 }
16500 {
16508 }
16512 {
16520 }
16524 }
16527 }
16529 /* Helper function for address compare simplifications in match.pd.
16530 OP0 and OP1 are ADDR_EXPR operands being compared by CODE.
16531 BASE0, BASE1, OFF0 and OFF1 are set by the function.
16532 GENERIC is true if GENERIC folding and false for GIMPLE folding.
16533 Returns 0 if OP0 is known to be unequal to OP1 regardless of OFF{0,1},
16534 1 if bases are known to be equal and OP0 cmp OP1 depends on OFF0 cmp OFF1,
16535 and 2 if unknown. */
16537 int
16541 {
16547 {
16550 }
16552 {
16555 }
16560 /* Punt in GENERIC on variables with value expressions;
16561 the value expressions might point to fields/elements
16562 of other vars etc. */
16568 {
16572 }
16581 {
16584 /* If the offsets are equal we can ignore overflow. */
16587 /* Or if we compare using pointers to decls or strings. */
16592 }
16608 /* This is a too conservative test that the STRING_CSTs
16609 will not end up being string-merged. */
16614 ;
16617 /* If this is a pointer comparison, ignore for now even
16618 valid equalities where one pointer is the offset zero
16619 of one object and the other to one past end of another one. */
16621 ;
16622 /* Assume that automatic variables can't be adjacent to global
16623 variables. */
16625 ;
16626 else
16627 {
16630 /* If sizes are unknown, e.g. VLA or not representable, punt. */
16636 /* If one offset is pointing (or could be) to the beginning of one
16637 object and the other is pointing to one past the last byte of the
16638 other object, punt. */
16643 /* If both offsets are the same, there are some cases we know that are
16644 ok. Either if we know they aren't zero, or if we know both sizes
16645 are no zero. */
16651 }
16653 }
16655 #if CHECKING_P
16659 /* Helper functions for writing tests of folding trees. */
16661 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
16663 static void
16665 tree constant)
16666 {
16668 }
16670 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
16671 wrapping WRAPPED_EXPR. */
16673 static void
16675 tree wrapped_expr)
16676 {
16681 }
16683 /* Verify that various arithmetic binary operations are folded
16684 correctly. */
16686 static void
16688 {
16694 /* Addition. */
16695 /* 1 <-- (0 + 1) */
16697 one);
16699 one);
16701 /* (nonlvalue)x <-- (x + 0) */
16703 x);
16705 /* Subtraction. */
16706 /* 0 <-- (x - x) */
16708 zero);
16710 x);
16712 /* Multiplication. */
16713 /* 0 <-- (x * 0) */
16715 zero);
16717 /* (nonlvalue)x <-- (x * 1) */
16719 x);
16720 }
16722 /* Verify that various binary operations on vectors are folded
16723 correctly. */
16725 static void
16727 {
16734 /* Verify equality tests that return a scalar boolean result. */
16747 }
16749 /* Verify folding of VEC_DUPLICATE_EXPRs. */
16751 static void
16753 {
16756 /* This will be 1 if VEC_MODE isn't a vector mode. */
16763 }
16765 /* Run all of the selftests within this file. */
16767 void
16769 {
16773 }