| blob | b647e5305aac3055ab0fb8bcb8c488b13efe0344 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2022 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
88 /* Nonzero if we are folding constants inside an initializer or a C++
89 manifestly-constant-evaluated context; zero otherwise.
90 Should be used when folding in initializer enables additional
91 optimizations. */
94 /* Nonzero if we are folding C++ manifestly-constant-evaluated context; zero
95 otherwise.
96 Should be used when certain constructs shouldn't be optimized
97 during folding in that context. */
100 /* The following constants represent a bit based encoding of GCC's
101 comparison operators. This encoding simplifies transformations
102 on relational comparison operators, such as AND and OR. */
120 };
154 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
155 Otherwise, return LOC. */
157 static location_t
159 {
162 }
164 /* Similar to protected_set_expr_location, but never modify x in place,
165 if location can and needs to be set, unshare it. */
169 {
175 {
178 }
180 }
181 \f
182 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
183 division and returns the quotient. Otherwise returns
184 NULL_TREE. */
186 tree
188 {
189 widest_int quo;
196 }
197 \f
198 /* This is nonzero if we should defer warnings about undefined
199 overflow. This facility exists because these warnings are a
200 special case. The code to estimate loop iterations does not want
201 to issue any warnings, since it works with expressions which do not
202 occur in user code. Various bits of cleanup code call fold(), but
203 only use the result if it has certain characteristics (e.g., is a
204 constant); that code only wants to issue a warning if the result is
205 used. */
209 /* If a warning about undefined overflow is deferred, this is the
210 warning. Note that this may cause us to turn two warnings into
211 one, but that is fine since it is sufficient to only give one
212 warning per expression. */
216 /* If a warning about undefined overflow is deferred, this is the
217 level at which the warning should be emitted. */
221 /* Start deferring overflow warnings. We could use a stack here to
222 permit nested calls, but at present it is not necessary. */
224 void
226 {
228 }
230 /* Stop deferring overflow warnings. If there is a pending warning,
231 and ISSUE is true, then issue the warning if appropriate. STMT is
232 the statement with which the warning should be associated (used for
233 location information); STMT may be NULL. CODE is the level of the
234 warning--a warn_strict_overflow_code value. This function will use
235 the smaller of CODE and the deferred code when deciding whether to
236 issue the warning. CODE may be zero to mean to always use the
237 deferred code. */
239 void
241 {
243 location_t locus;
248 {
254 }
265 /* Use the smallest code level when deciding to issue the
266 warning. */
275 else
278 }
280 /* Stop deferring overflow warnings, ignoring any deferred
281 warnings. */
283 void
285 {
287 }
289 /* Whether we are deferring overflow warnings. */
291 bool
293 {
295 }
297 /* This is called when we fold something based on the fact that signed
298 overflow is undefined. */
300 void
302 {
304 {
307 {
310 }
311 }
314 }
315 \f
316 /* Return true if the built-in mathematical function specified by CODE
317 is odd, i.e. -f(x) == f(-x). */
319 bool
321 {
323 {
324 CASE_CFN_ASIN:
325 CASE_CFN_ASINH:
326 CASE_CFN_ATAN:
327 CASE_CFN_ATANH:
328 CASE_CFN_CASIN:
329 CASE_CFN_CASINH:
330 CASE_CFN_CATAN:
331 CASE_CFN_CATANH:
332 CASE_CFN_CBRT:
333 CASE_CFN_CPROJ:
334 CASE_CFN_CSIN:
335 CASE_CFN_CSINH:
336 CASE_CFN_CTAN:
337 CASE_CFN_CTANH:
338 CASE_CFN_ERF:
339 CASE_CFN_LLROUND:
340 CASE_CFN_LROUND:
341 CASE_CFN_ROUND:
342 CASE_CFN_ROUNDEVEN:
343 CASE_CFN_ROUNDEVEN_FN:
344 CASE_CFN_SIN:
345 CASE_CFN_SINH:
346 CASE_CFN_TAN:
347 CASE_CFN_TANH:
348 CASE_CFN_TRUNC:
351 CASE_CFN_LLRINT:
352 CASE_CFN_LRINT:
353 CASE_CFN_NEARBYINT:
354 CASE_CFN_RINT:
359 }
361 }
363 /* Check whether we may negate an integer constant T without causing
364 overflow. */
366 bool
368 {
369 tree type;
378 }
380 /* Determine whether an expression T can be cheaply negated using
381 the function negate_expr without introducing undefined overflow. */
383 static bool
385 {
386 tree type;
395 {
400 /* Check that -CST will not overflow type. */
413 /* We want to canonicalize to positive real constants. Pretend
414 that only negative ones can be easily negated. */
422 {
426 /* Steps don't prevent negation. */
433 }
448 /* -(A + B) -> (-B) - A. */
451 /* -(A + B) -> (-A) - B. */
455 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
464 /* INT_MIN/n * n doesn't overflow while negating one operand it does
465 if n is a (negative) power of two. */
476 /* Fall through. */
489 /* In general we can't negate A in A / B, because if A is INT_MIN and
490 B is not 1 we change the sign of the result. */
494 /* In general we can't negate B in A / B, because if A is INT_MIN and
495 B is 1, we may turn this into INT_MIN / -1 which is undefined
496 and actually traps on some architectures. */
505 /* Negate -((double)float) as (double)(-float). */
507 {
511 }
515 /* Negate -f(x) as f(-x). */
521 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
523 {
527 }
532 }
534 }
536 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
537 simplification is possible.
538 If negate_expr_p would return true for T, NULL_TREE will never be
539 returned. */
541 static tree
543 {
545 tree tem;
548 {
549 /* Convert - (~A) to A + 1. */
573 {
578 }
582 {
583 tree_vector_builder elts;
587 {
592 }
595 }
618 {
619 /* -(A + B) -> (-B) - A. */
621 {
625 }
627 /* -(A + B) -> (-A) - B. */
629 {
633 }
634 }
638 /* - (A - B) -> B - A */
649 /* Fall through. */
653 {
662 }
670 /* In general we can't negate A in A / B, because if A is INT_MIN and
671 B is not 1 we change the sign of the result. */
677 /* In general we can't negate B in A / B, because if A is INT_MIN and
678 B is 1, we may turn this into INT_MIN / -1 which is undefined
679 and actually traps on some architectures. */
691 /* Convert -((double)float) into (double)(-float). */
693 {
697 }
701 /* Negate -f(x) as f(-x). */
704 {
710 }
714 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
716 {
719 {
726 }
727 }
732 }
735 }
737 /* A wrapper for fold_negate_expr_1. */
739 static tree
741 {
748 }
750 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T cannot be
751 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
752 return NULL_TREE. */
754 static tree
756 {
758 location_t loc;
771 }
772 \f
773 /* Split a tree IN into a constant, literal and variable parts that could be
774 combined with CODE to make IN. "constant" means an expression with
775 TREE_CONSTANT but that isn't an actual constant. CODE must be a
776 commutative arithmetic operation. Store the constant part into *CONP,
777 the literal in *LITP and return the variable part. If a part isn't
778 present, set it to null. If the tree does not decompose in this way,
779 return the entire tree as the variable part and the other parts as null.
781 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
782 case, we negate an operand that was subtracted. Except if it is a
783 literal for which we use *MINUS_LITP instead.
785 If NEGATE_P is true, we are negating all of IN, again except a literal
786 for which we use *MINUS_LITP instead. If a variable part is of pointer
787 type, it is negated after converting to TYPE. This prevents us from
788 generating illegal MINUS pointer expression. LOC is the location of
789 the converted variable part.
791 If IN is itself a literal or constant, return it as appropriate.
793 Note that we do not guarantee that any of the three values will be the
794 same type as IN, but they will have the same signedness and mode. */
796 static tree
800 {
808 /* Strip any conversions that don't change the machine mode or signedness. */
817 /* We can associate addition and subtraction together (even
818 though the C standard doesn't say so) for integers because
819 the value is not affected. For reals, the value might be
820 affected, so we can't. */
826 {
832 /* First see if either of the operands is a literal, then a constant. */
845 /* If we haven't dealt with either operand, this is not a case we can
846 decompose. Otherwise, VAR is either of the ones remaining, if any. */
851 else
854 /* Now do any needed negations. */
861 }
866 {
867 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
868 when IN is constant. */
871 }
872 else
876 {
889 }
899 }
901 /* Re-associate trees split by the above function. T1 and T2 are
902 either expressions to associate or null. Return the new
903 expression, if any. LOC is the location of the new expression. If
904 we build an operation, do it in TYPE and with CODE. */
906 static tree
908 {
910 {
913 }
917 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
918 try to fold this since we will have infinite recursion. But do
919 deal with any NEGATE_EXPRs. */
923 {
925 {
938 }
940 {
943 }
947 }
951 }
952 \f
953 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
954 for use in int_const_binop, size_binop and size_diffop. */
956 static bool
958 {
965 {
974 }
979 }
981 /* Combine two wide ints ARG1 and ARG2 under operation CODE to produce
982 a new constant in RES. Return FALSE if we don't know how to
983 evaluate CODE at compile-time. */
985 bool
989 {
990 wide_int tmp;
993 {
1015 /* It's unclear from the C standard whether shifts can overflow.
1016 The following code ignores overflow; perhaps a C standard
1017 interpretation ruling is needed. */
1024 {
1028 else
1030 }
1031 else
1036 else
1115 }
1117 }
1119 /* Combine two poly int's ARG1 and ARG2 under operation CODE to
1120 produce a new constant in RES. Return FALSE if we don't know how
1121 to evaluate CODE at compile-time. */
1123 static bool
1127 {
1131 {
1149 else
1156 else
1169 }
1171 }
1173 /* Combine two integer constants ARG1 and ARG2 under operation CODE to
1174 produce a new constant. Return NULL_TREE if we don't know how to
1175 evaluate CODE at compile-time. */
1177 tree
1180 {
1181 poly_wide_int poly_res;
1187 {
1193 }
1202 }
1204 /* Return true if binary operation OP distributes over addition in operand
1205 OPNO, with the other operand being held constant. OPNO counts from 1. */
1207 static bool
1209 {
1211 {
1222 }
1223 }
1225 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1226 constant. We assume ARG1 and ARG2 have the same data type, or at least
1227 are the same kind of constant and the same machine mode. Return zero if
1228 combining the constants is not allowed in the current operating mode. */
1230 static tree
1232 {
1233 /* Sanity check for the recursive cases. */
1241 {
1247 }
1250 {
1251 machine_mode mode;
1252 REAL_VALUE_TYPE d1;
1253 REAL_VALUE_TYPE d2;
1254 REAL_VALUE_TYPE value;
1255 REAL_VALUE_TYPE result;
1259 /* The following codes are handled by real_arithmetic. */
1261 {
1272 }
1280 /* Don't perform operation if we honor signaling NaNs and
1281 either operand is a signaling NaN. */
1287 /* Don't perform operation if it would raise a division
1288 by zero exception. */
1294 /* If either operand is a NaN, just return it. Otherwise, set up
1295 for floating-point trap; we return an overflow. */
1297 {
1298 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1299 is off. */
1303 }
1305 {
1306 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1307 is off. */
1311 }
1316 /* Don't constant fold this floating point operation if
1317 both operands are not NaN but the result is NaN, and
1318 flag_trapping_math. Such operations should raise an
1319 invalid operation exception. */
1327 /* Don't constant fold this floating point operation if
1328 the result has overflowed and flag_trapping_math. */
1336 /* Don't constant fold this floating point operation if the
1337 result may dependent upon the run-time rounding mode and
1338 flag_rounding_math is set, or if GCC's software emulation
1339 is unable to accurately represent the result. */
1349 }
1352 {
1353 FIXED_VALUE_TYPE f1;
1354 FIXED_VALUE_TYPE f2;
1355 FIXED_VALUE_TYPE result;
1360 /* The following codes are handled by fixed_arithmetic. */
1362 {
1374 {
1381 }
1386 }
1393 /* Propagate overflow flags. */
1397 }
1400 {
1409 {
1420 mpc_mul);
1434 mpc_div);
1435 /* Fallthru. */
1441 {
1442 /* Keep this algorithm in sync with
1443 tree-complex.cc:expand_complex_div_straight().
1445 Expand complex division to scalars, straightforward algorithm.
1446 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1447 t = br*br + bi*bi
1448 */
1449 tree magsquared
1453 tree t1
1457 tree t2
1464 }
1465 else
1466 {
1467 /* Keep this algorithm in sync with
1468 tree-complex.cc:expand_complex_div_wide().
1470 Expand complex division to scalars, modified algorithm to minimize
1471 overflow with wide input ranges. */
1477 {
1478 /* In the TRUE branch, we compute
1479 ratio = br/bi;
1480 div = (br * ratio) + bi;
1481 tr = (ar * ratio) + ai;
1482 ti = (ai * ratio) - ar;
1483 tr = tr / div;
1484 ti = ti / div; */
1495 }
1496 else
1497 {
1498 /* In the FALSE branch, we compute
1499 ratio = d/c;
1500 divisor = (d * ratio) + c;
1501 tr = (b * ratio) + a;
1502 ti = b - (a * ratio);
1503 tr = tr / div;
1504 ti = ti / div; */
1516 }
1517 }
1522 }
1526 }
1532 {
1537 /* We can operate directly on the encoding if:
1539 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1540 implies
1541 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1543 Addition and subtraction are the supported operators
1544 for which this is true. */
1547 /* We can operate directly on stepped encodings if:
1549 a3 - a2 == a2 - a1
1550 implies:
1551 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1553 which is true if (x -> x op c) distributes over addition. */
1555 else
1556 /* Similarly in reverse. */
1558 tree_vector_builder elts;
1563 {
1569 /* It is possible that const_binop cannot handle the given
1570 code and return NULL_TREE */
1574 }
1577 }
1579 /* Shifts allow a scalar offset for a vector. */
1582 {
1585 tree_vector_builder elts;
1590 {
1595 /* It is possible that const_binop cannot handle the given
1596 code and return NULL_TREE. */
1600 }
1603 }
1605 }
1607 /* Overload that adds a TYPE parameter to be able to dispatch
1608 to fold_relational_const. */
1610 tree
1612 {
1616 /* ??? Until we make the const_binop worker take the type of the
1617 result as argument put those cases that need it here. */
1619 {
1636 {
1641 }
1647 {
1663 {
1668 ? NOP_EXPR
1675 }
1678 }
1684 {
1707 {
1720 }
1723 }
1726 }
1731 /* Make sure type and arg0 have the same saturating flag. */
1736 }
1738 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1739 Return zero if computing the constants is not possible. */
1741 tree
1743 {
1744 /* Don't perform the operation, other than NEGATE and ABS, if
1745 flag_signaling_nans is on and the operand is a signaling NaN. */
1755 {
1756 CASE_CONVERT:
1763 /* If the source address is 0, and the source address space
1764 cannot have a valid object at 0, fold to dest type null. */
1775 {
1776 /* Can't call fold_negate_const directly here as that doesn't
1777 handle all cases and we might not be able to negate some
1778 constants. */
1783 }
1793 {
1797 }
1805 /* Perform BIT_NOT_EXPR on each element individually. */
1807 {
1808 tree elem;
1810 /* This can cope with stepped encodings because ~x == -1 - x. */
1811 tree_vector_builder elements;
1815 {
1821 }
1824 }
1848 {
1871 else
1876 {
1882 }
1885 }
1894 }
1897 }
1899 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1900 indicates which particular sizetype to create. */
1902 tree
1904 {
1906 }
1907 \f
1908 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1909 is a tree code. The type of the result is taken from the operands.
1910 Both must be equivalent integer types, ala int_binop_types_match_p.
1911 If the operands are constant, so is the result. */
1913 tree
1915 {
1924 /* Handle the special case of two poly_int constants faster. */
1926 {
1927 /* And some specific cases even faster than that. */
1929 {
1936 }
1938 {
1942 }
1944 {
1948 }
1950 /* Handle general case of two integer constants. For sizetype
1951 constant calculations we always want to know about overflow,
1952 even in the unsigned case. */
1956 }
1959 }
1961 /* Given two values, either both of sizetype or both of bitsizetype,
1962 compute the difference between the two values. Return the value
1963 in signed type corresponding to the type of the operands. */
1965 tree
1967 {
1969 tree ctype;
1974 /* If the type is already signed, just do the simple thing. */
1982 else
1985 /* If either operand is not a constant, do the conversions to the signed
1986 type and subtract. The hardware will do the right thing with any
1987 overflow in the subtraction. */
1993 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1994 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1995 overflow) and negate (which can't either). Special-case a result
1996 of zero while we're here. */
2002 else
2006 MINUS_EXPR,
2008 }
2009 \f
2010 /* A subroutine of fold_convert_const handling conversions of an
2011 INTEGER_CST to another integer type. */
2013 static tree
2015 {
2016 /* Given an integer constant, make new constant with new type,
2017 appropriately sign-extended or truncated. Use widest_int
2018 so that any extension is done according ARG1's type. */
2022 }
2024 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2025 to an integer type. */
2027 static tree
2029 {
2031 tree t;
2033 /* The following code implements the floating point to integer
2034 conversion rules required by the Java Language Specification,
2035 that IEEE NaNs are mapped to zero and values that overflow
2036 the target precision saturate, i.e. values greater than
2037 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2038 are mapped to INT_MIN. These semantics are allowed by the
2039 C and C++ standards that simply state that the behavior of
2040 FP-to-integer conversion is unspecified upon overflow. */
2042 wide_int val;
2043 REAL_VALUE_TYPE r;
2047 {
2054 }
2056 /* If R is NaN, return zero and show we have an overflow. */
2058 {
2061 }
2063 /* See if R is less than the lower bound or greater than the
2064 upper bound. */
2067 {
2071 {
2074 }
2075 }
2078 {
2081 {
2084 {
2087 }
2088 }
2089 }
2096 }
2098 /* A subroutine of fold_convert_const handling conversions of a
2099 FIXED_CST to an integer type. */
2101 static tree
2103 {
2104 tree t;
2106 scalar_mode mode;
2108 /* Right shift FIXED_CST to temp by fbit. */
2112 {
2114 HOST_BITS_PER_DOUBLE_INT,
2117 /* Left shift temp to temp_trunc by fbit. */
2119 HOST_BITS_PER_DOUBLE_INT,
2121 }
2122 else
2123 {
2126 }
2128 /* If FIXED_CST is negative, we need to round the value toward 0.
2129 By checking if the fractional bits are not zero to add 1 to temp. */
2135 /* Given a fixed-point constant, make new constant with new type,
2136 appropriately sign-extended or truncated. */
2144 }
2146 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2147 to another floating point type. */
2149 static tree
2151 {
2152 REAL_VALUE_TYPE value;
2153 tree t;
2155 /* Don't perform the operation if flag_signaling_nans is on
2156 and the operand is a signaling NaN. */
2161 /* With flag_rounding_math we should respect the current rounding mode
2162 unless the conversion is exact. */
2170 /* If converting an infinity or NAN to a representation that doesn't
2171 have one, set the overflow bit so that we can produce some kind of
2172 error message at the appropriate point if necessary. It's not the
2173 most user-friendly message, but it's better than nothing. */
2180 /* Regular overflow, conversion produced an infinity in a mode that
2181 can't represent them. */
2186 else
2189 }
2191 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2192 to a floating point type. */
2194 static tree
2196 {
2197 REAL_VALUE_TYPE value;
2198 tree t;
2206 }
2208 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2209 to another fixed-point type. */
2211 static tree
2213 {
2214 FIXED_VALUE_TYPE value;
2215 tree t;
2222 /* Propagate overflow flags. */
2226 }
2228 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2229 to a fixed-point type. */
2231 static tree
2233 {
2234 FIXED_VALUE_TYPE value;
2235 tree t;
2237 double_int di;
2244 else
2252 /* Propagate overflow flags. */
2256 }
2258 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2259 to a fixed-point type. */
2261 static tree
2263 {
2264 FIXED_VALUE_TYPE value;
2265 tree t;
2273 /* Propagate overflow flags. */
2277 }
2279 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2280 type TYPE. If no simplification can be done return NULL_TREE. */
2282 static tree
2284 {
2289 /* We can't widen types, since the runtime value could overflow the
2290 original type before being extended to the new type. */
2301 {
2308 }
2310 {
2312 {
2314 /* Avoid the folding if flag_rounding_math is on and the
2315 conversion is not exact. */
2317 {
2323 }
2325 }
2330 }
2332 {
2339 }
2341 {
2344 {
2347 /* We can't handle steps directly when extending, since the
2348 values need to wrap at the original precision first. */
2349 bool step_ok_p
2353 tree_vector_builder v;
2358 {
2364 }
2366 }
2367 }
2369 }
2371 /* Construct a vector of zero elements of vector type TYPE. */
2373 static tree
2375 {
2376 tree t;
2380 }
2382 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2384 bool
2386 {
2401 {
2423 }
2424 }
2426 /* Convert expression ARG to type TYPE. Used by the middle-end for
2427 simple conversions in preference to calling the front-end's convert. */
2429 tree
2431 {
2433 tree tem;
2444 {
2447 /* Handle conversions between pointers to different address spaces. */
2452 /* fall through */
2457 {
2461 }
2475 {
2479 }
2481 {
2485 }
2487 {
2491 }
2494 {
2512 }
2517 {
2521 }
2524 {
2538 }
2542 {
2551 integer_zero_node));
2553 {
2557 {
2563 }
2571 }
2575 }
2593 }
2594 fold_convert_exit:
2597 }
2598 \f
2599 /* Return false if expr can be assumed not to be an lvalue, true
2600 otherwise. */
2602 static bool
2604 {
2605 /* We only need to wrap lvalue tree codes. */
2607 {
2639 /* Assume the worst for front-end tree codes. */
2643 }
2646 }
2648 /* Return an expr equal to X but certainly not valid as an lvalue. */
2650 tree
2652 {
2653 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2654 us. */
2661 }
2662 \f
2663 /* Given a tree comparison code, return the code that is the logical inverse.
2664 It is generally not safe to do this for floating-point comparisons, except
2665 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2666 ERROR_MARK in this case. */
2668 enum tree_code
2670 {
2676 {
2707 }
2708 }
2710 /* Similar, but return the comparison that results if the operands are
2711 swapped. This is safe for floating-point. */
2713 enum tree_code
2715 {
2717 {
2743 }
2744 }
2747 /* Convert a comparison tree code from an enum tree_code representation
2748 into a compcode bit-based encoding. This function is the inverse of
2749 compcode_to_comparison. */
2751 static enum comparison_code
2753 {
2755 {
2786 }
2787 }
2789 /* Convert a compcode bit-based encoding of a comparison operator back
2790 to GCC's enum tree_code representation. This function is the
2791 inverse of comparison_to_compcode. */
2793 static enum tree_code
2795 {
2797 {
2828 }
2829 }
2831 /* Return true if COND1 tests the opposite condition of COND2. */
2833 bool
2835 {
2838 && (invert_tree_comparison
2845 }
2847 /* Return a tree for the comparison which is the combination of
2848 doing the AND or OR (depending on CODE) of the two operations LCODE
2849 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2850 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2851 if this makes the transformation invalid. */
2853 tree
2858 {
2865 {
2876 }
2879 {
2880 /* Eliminate unordered comparisons, as well as LTGT and ORD
2881 which are not used unless the mode has NaNs. */
2887 }
2889 {
2890 /* Check that the original operation and the optimized ones will trap
2891 under the same condition. */
2902 /* In a short-circuited boolean expression the LHS might be
2903 such that the RHS, if evaluated, will never trap. For
2904 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2905 if neither x nor y is NaN. (This is a mixed blessing: for
2906 example, the expression above will never trap, hence
2907 optimizing it to x < y would be invalid). */
2912 /* If the comparison was short-circuited, and only the RHS
2913 trapped, we may now generate a spurious trap. */
2918 /* If we changed the conditions that cause a trap, we lose. */
2921 }
2927 else
2928 {
2933 }
2934 }
2935 \f
2936 /* Return nonzero if two operands (typically of the same tree node)
2937 are necessarily equal. FLAGS modifies behavior as follows:
2939 If OEP_ONLY_CONST is set, only return nonzero for constants.
2940 This function tests whether the operands are indistinguishable;
2941 it does not test whether they are equal using C's == operation.
2942 The distinction is important for IEEE floating point, because
2943 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2944 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2946 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2947 even though it may hold multiple values during a function.
2948 This is because a GCC tree node guarantees that nothing else is
2949 executed between the evaluation of its "operands" (which may often
2950 be evaluated in arbitrary order). Hence if the operands themselves
2951 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2952 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2953 unset means assuming isochronic (or instantaneous) tree equivalence.
2954 Unless comparing arbitrary expression trees, such as from different
2955 statements, this flag can usually be left unset.
2957 If OEP_PURE_SAME is set, then pure functions with identical arguments
2958 are considered the same. It is used when the caller has other ways
2959 to ensure that global memory is unchanged in between.
2961 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2962 not values of expressions.
2964 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2965 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2967 If OEP_BITWISE is set, then require the values to be bitwise identical
2968 rather than simply numerically equal. Do not take advantage of things
2969 like math-related flags or undefined behavior; only return true for
2970 values that are provably bitwise identical in all circumstances.
2972 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2973 any operand with side effect. This is unnecesarily conservative in the
2974 case we know that arg0 and arg1 are in disjoint code paths (such as in
2975 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2976 addresses with TREE_CONSTANT flag set so we know that &var == &var
2977 even if var is volatile. */
2979 bool
2982 {
2990 /* If either is ERROR_MARK, they aren't equal. */
2996 /* Similar, if either does not have a type (like a template id),
2997 they aren't equal. */
3001 /* Bitwise identity makes no sense if the values have different layouts. */
3006 /* We cannot consider pointers to different address space equal. */
3013 /* Check equality of integer constants before bailing out due to
3014 precision differences. */
3016 {
3017 /* Address of INTEGER_CST is not defined; check that we did not forget
3018 to drop the OEP_ADDRESS_OF flags. */
3021 }
3024 {
3025 /* If both types don't have the same signedness, then we can't consider
3026 them equal. We must check this before the STRIP_NOPS calls
3027 because they may change the signedness of the arguments. As pointers
3028 strictly don't have a signedness, require either two pointers or
3029 two non-pointers as well. */
3035 /* If both types don't have the same precision, then it is not safe
3036 to strip NOPs. */
3043 }
3044 #if 0
3045 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
3046 sanity check once the issue is solved. */
3047 else
3048 /* Addresses of conversions and SSA_NAMEs (and many other things)
3049 are not defined. Check that we did not forget to drop the
3050 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3053 #endif
3055 /* In case both args are comparisons but with different comparison
3056 code, try to swap the comparison operands of one arg to produce
3057 a match and compare that variant. */
3061 {
3069 }
3072 {
3073 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3075 ;
3077 {
3078 /* If we are interested in comparing addresses ignore
3079 MEM_REF wrappings of the base that can appear just for
3080 TBAA reasons. */
3094 }
3095 else
3097 }
3099 /* When not checking adddresses, this is needed for conversions and for
3100 COMPONENT_REF. Might as well play it safe and always test this. */
3107 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3108 We don't care about side effects in that case because the SAVE_EXPR
3109 takes care of that for us. In all other cases, two expressions are
3110 equal if they have no side effects. If we have two identical
3111 expressions with side effects that should be treated the same due
3112 to the only side effects being identical SAVE_EXPR's, that will
3113 be detected in the recursive calls below.
3114 If we are taking an invariant address of two identical objects
3115 they are necessarily equal as well. */
3122 /* Next handle constant cases, those for which we can return 1 even
3123 if ONLY_CONST is set. */
3126 {
3139 {
3140 /* If we do not distinguish between signed and unsigned zero,
3141 consider them equal. */
3144 }
3148 {
3163 }
3167 flags)
3169 flags));
3180 flags | OEP_ADDRESS_OF
3183 /* In GIMPLE empty constructors are allowed in initializers of
3184 aggregates. */
3188 }
3190 /* Don't handle more cases for OEP_BITWISE, since we can't guarantee that
3191 two instances of undefined behavior will give identical results. */
3195 /* Define macros to test an operand from arg0 and arg1 for equality and a
3196 variant that allows null and views null as being different from any
3197 non-null value. In the latter case, if either is null, the both
3198 must be; otherwise, do the normal comparison. */
3199 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3200 TREE_OPERAND (arg1, N), flags)
3202 #define OP_SAME_WITH_NULL(N) \
3203 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3204 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3207 {
3209 /* Two conversions are equal only if signedness and modes match. */
3211 {
3212 CASE_CONVERT:
3220 }
3230 /* For commutative ops, allow the other order. */
3238 /* If either of the pointer (or reference) expressions we are
3239 dereferencing contain a side effect, these cannot be equal,
3240 but their addresses can be. */
3247 {
3250 {
3254 /* Verify that the access types are compatible. */
3258 }
3263 /* Require the same offset. */
3269 /* Fallthru. */
3277 {
3278 /* Require equal access sizes */
3284 flags)))
3286 /* Verify that access happens in similar types. */
3289 /* Verify that accesses are TBAA compatible. */
3298 /* Verify that alignment is compatible. */
3302 }
3305 /* TARGET_MEM_REF require equal extra operands. */
3316 /* Compare the array index by value if it is constant first as we
3317 may have different types but same value here. */
3323 /* Compare low bound and element size as with OEP_ADDRESS_OF
3324 we have to account for the offset of the ref. */
3329 array_ref_low_bound
3333 array_ref_element_size
3335 flags))));
3338 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3339 may be NULL when we're called to compare MEM_EXPRs. */
3342 {
3345 /* Most of time we only need to compare FIELD_DECLs for equality.
3346 However when determining address look into actual offsets.
3347 These may match for unions and unshared record types. */
3350 {
3353 {
3360 /* Non-FIELD_DECL operands can appear in C++ templates. */
3367 flags))
3369 }
3370 else
3372 }
3373 }
3384 }
3388 {
3390 /* Be sure we pass right ADDRESS_OF flag. */
3407 /* The multiplcation operands are commutative. */
3408 /* FALLTHRU */
3416 /* Otherwise take into account this is a commutative operation. */
3429 /* BIT_INSERT_EXPR has an implict operand as the type precision
3430 of op1. Need to check to make sure they are the same. */
3436 /* FALLTHRU */
3461 /* Virtual table reference. */
3473 {
3478 }
3483 }
3487 {
3491 /* If not both CALL_EXPRs are either internal or normal function
3492 functions, then they are not equal. */
3495 {
3496 /* If the CALL_EXPRs call different internal functions, then they
3497 are not equal. */
3500 }
3501 else
3502 {
3503 /* If the CALL_EXPRs call different functions, then they are not
3504 equal. */
3506 flags))
3508 }
3510 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3511 {
3515 else
3519 }
3521 /* Now see if all the arguments are the same. */
3522 {
3533 /* If we get here and both argument lists are exhausted
3534 then the CALL_EXPRs are equal. */
3536 }
3539 }
3542 /* Consider __builtin_sqrt equal to sqrt. */
3552 {
3553 /* Consider decls with the same name equal. The caller needs
3554 to make sure they refer to the same entity (such as a function
3555 formal parameter). */
3561 }
3566 {
3570 /* In GIMPLE constructors are used only to build vectors from
3571 elements. Individual elements in the constructor must be
3572 indexed in increasing order and form an initial sequence.
3574 We make no effort to compare constructors in generic.
3575 (see sem_variable::equals in ipa-icf which can do so for
3576 constants). */
3581 /* Be sure that vectors constructed have the same representation.
3582 We only tested element precision and modes to match.
3583 Vectors may be BLKmode and thus also check that the number of
3584 parts match. */
3597 {
3602 /* In GIMPLE the indexes can be either NULL or matching i.
3603 Double check this so we won't get false
3604 positives for GENERIC. */
3612 }
3614 }
3617 {
3618 /* Compare the STATEMENT_LISTs. */
3624 {
3625 /* The lists don't have the same number of statements. */
3631 flags & (OEP_LEXICOGRAPHIC
3634 }
3635 }
3640 {
3651 }
3655 }
3657 #undef OP_SAME
3658 #undef OP_SAME_WITH_NULL
3659 }
3661 /* Generate a hash value for an expression. This can be used iteratively
3662 by passing a previous result as the HSTATE argument. */
3664 void
3667 {
3673 {
3676 }
3686 {
3687 /* Alas, constants aren't shared, so we can't rely on pointer
3688 identity. */
3698 {
3702 else
3706 }
3708 {
3712 }
3722 {
3729 }
3731 /* We can just compare by pointer. */
3735 /* The node itself doesn't matter. */
3739 /* Ignore. */
3742 /* A list of expressions, for a CALL_EXPR or as the elements of a
3743 VECTOR_CST. */
3748 {
3754 {
3755 /* In GIMPLE the indexes can be either NULL or matching i. */
3760 }
3762 }
3764 {
3765 tree_stmt_iterator i;
3770 }
3779 /* When referring to a built-in FUNCTION_DECL, use the __builtin__ form.
3780 Otherwise nodes that compare equal according to operand_equal_p might
3781 get different hash codes. However, don't do this for machine specific
3782 or front end builtins, since the function code is overloaded in those
3783 cases. */
3786 {
3789 }
3790 /* FALL THROUGH */
3793 {
3797 }
3801 {
3802 /* DECL's have a unique ID */
3804 }
3806 {
3807 /* For comparisons that can be swapped, use the lower
3808 tree code. */
3815 }
3817 {
3818 /* NOP_EXPR and CONVERT_EXPR are considered equal by
3819 operand_equal_p. */
3823 /* Don't hash the type, that can lead to having nodes which
3824 compare equal according to operand_equal_p, but which
3825 have different hash codes. Make sure to include signedness
3826 in the hash computation. */
3829 }
3830 /* For OEP_ADDRESS_OF, hash MEM_EXPR[&decl, 0] the same as decl. */
3838 /* Don't ICE on FE specific trees, or their arguments etc.
3839 during operand_equal_p hash verification. */
3842 else
3843 {
3849 {
3865 {
3870 else
3871 {
3877 }
3879 }
3893 {
3894 /* The multiplication operands are commutative. */
3901 }
3909 /* For TARGET_EXPR, just hash on the TARGET_EXPR_SLOT.
3910 Usually different TARGET_EXPRs just should use
3911 different temporaries in their slots. */
3916 /* Virtual table reference. */
3924 {
3926 /* We compute mangled names only when free_lang_data is run.
3927 In that case we can hash precisely. */
3930 hstate.add_object
3931 (IDENTIFIER_HASH_VALUE
3933 }
3937 }
3939 /* Don't hash the type, that can lead to having nodes which
3940 compare equal according to operand_equal_p, but which
3941 have different hash codes. */
3943 {
3944 /* Make sure to include signness in the hash computation. */
3947 }
3950 {
3951 /* It's a commutative expression. We want to hash it the same
3952 however it appears. We do this by first hashing both operands
3953 and then rehashing based on the order of their independent
3954 hashes. */
3959 }
3960 else
3964 }
3966 }
3967 }
3969 bool
3972 {
3973 /* When checking and unless comparing DECL names, verify that if
3974 the outermost operand_equal_p call returns non-zero then ARG0
3975 and ARG1 have the same hash value. */
3977 {
3979 {
3981 {
3988 }
3990 }
3991 else
3995 }
3998 }
4003 /* Conveinece wrapper around operand_compare class because usually we do
4004 not need to play with the valueizer. */
4006 bool
4008 {
4010 }
4012 namespace inchash
4013 {
4015 /* Generate a hash value for an expression. This can be used iteratively
4016 by passing a previous result as the HSTATE argument.
4018 This function is intended to produce the same hash for expressions which
4019 would compare equal using operand_equal_p. */
4020 void
4022 {
4024 }
4026 }
4027 \f
4028 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
4029 with a different signedness or a narrower precision. */
4031 static bool
4033 {
4041 /* Discard any conversions that don't change the modes of ARG0 and ARG1
4042 and see if the inner values are the same. This removes any
4043 signedness comparison, which doesn't matter here. */
4051 /* Discard a single widening conversion from ARG1 and see if the inner
4052 value is the same as ARG0. */
4061 }
4062 \f
4063 /* See if ARG is an expression that is either a comparison or is performing
4064 arithmetic on comparisons. The comparisons must only be comparing
4065 two different values, which will be stored in *CVAL1 and *CVAL2; if
4066 they are nonzero it means that some operands have already been found.
4067 No variables may be used anywhere else in the expression except in the
4068 comparisons.
4070 If this is true, return 1. Otherwise, return zero. */
4072 static bool
4074 {
4078 /* We can handle some of the tcc_expression cases here. */
4087 {
4106 /* First see if we can handle the first operand, then the second. For
4107 the second operand, we know *CVAL1 can't be zero. It must be that
4108 one side of the comparison is each of the values; test for the
4109 case where this isn't true by failing if the two operands
4110 are the same. */
4119 ;
4123 ;
4124 else
4128 ;
4132 ;
4133 else
4140 }
4141 }
4142 \f
4143 /* ARG is a tree that is known to contain just arithmetic operations and
4144 comparisons. Evaluate the operations in the tree substituting NEW0 for
4145 any occurrence of OLD0 as an operand of a comparison and likewise for
4146 NEW1 and OLD1. */
4148 static tree
4151 {
4156 /* We can handle some of the tcc_expression cases here. */
4164 {
4179 {
4198 }
4199 /* Fall through - ??? */
4202 {
4206 /* We need to check both for exact equality and tree equality. The
4207 former will be true if the operand has a side-effect. In that
4208 case, we know the operand occurred exactly once. */
4221 }
4225 }
4226 }
4227 \f
4228 /* Return a tree for the case when the result of an expression is RESULT
4229 converted to TYPE and OMITTED was previously an operand of the expression
4230 but is now not needed (e.g., we folded OMITTED * 0).
4232 If OMITTED has side effects, we must evaluate it. Otherwise, just do
4233 the conversion of RESULT to TYPE. */
4235 tree
4237 {
4240 /* If the resulting operand is an empty statement, just return the omitted
4241 statement casted to void. */
4251 }
4253 /* Return a tree for the case when the result of an expression is RESULT
4254 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
4255 of the expression but are now not needed.
4257 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
4258 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
4259 evaluated before OMITTED2. Otherwise, if neither has side effects,
4260 just do the conversion of RESULT to TYPE. */
4262 tree
4265 {
4274 }
4276 \f
4277 /* Return a simplified tree node for the truth-negation of ARG. This
4278 never alters ARG itself. We assume that ARG is an operation that
4279 returns a truth value (0 or 1).
4281 FIXME: one would think we would fold the result, but it causes
4282 problems with the dominator optimizer. */
4284 static tree
4286 {
4291 /* If this is a comparison, we can simply invert it, except for
4292 floating-point non-equality comparisons, in which case we just
4293 enclose a TRUTH_NOT_EXPR around what we have. */
4296 {
4299 && flag_trapping_math
4312 }
4315 {
4334 /* Here we can invert either operand. We invert the first operand
4335 unless the second operand is a TRUTH_NOT_EXPR in which case our
4336 result is the XOR of the first operand with the inside of the
4337 negation of the second operand. */
4342 else
4365 {
4372 /* A COND_EXPR may have a throw as one operand, which
4373 then has void type. Just leave void operands
4374 as they are. */
4380 }
4392 CASE_CONVERT:
4396 /* fall through */
4418 }
4419 }
4421 /* Fold the truth-negation of ARG. This never alters ARG itself. We
4422 assume that ARG is an operation that returns a truth value (0 or 1
4423 for scalars, 0 or -1 for vectors). Return the folded expression if
4424 folding is successful. Otherwise, return NULL_TREE. */
4426 static tree
4428 {
4431 ? BIT_NOT_EXPR
4434 }
4436 /* Return a simplified tree node for the truth-negation of ARG. This
4437 never alters ARG itself. We assume that ARG is an operation that
4438 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
4440 tree
4442 {
4448 ? BIT_NOT_EXPR
4451 }
4452 \f
4453 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4454 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
4455 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
4456 is the original memory reference used to preserve the alias set of
4457 the access. */
4459 static tree
4463 {
4466 /* Attempt not to lose the access path if possible. */
4468 {
4470 machine_mode nmode;
4472 tree noffset;
4480 && !reversep
4481 && !nreversep
4483 {
4486 }
4487 }
4496 {
4503 }
4518 }
4520 /* Optimize a bit-field compare.
4522 There are two cases: First is a compare against a constant and the
4523 second is a comparison of two items where the fields are at the same
4524 bit position relative to the start of a chunk (byte, halfword, word)
4525 large enough to contain it. In these cases we can avoid the shift
4526 implicit in bitfield extractions.
4528 For constants, we emit a compare of the shifted constant with the
4529 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4530 compared. For two fields at the same position, we do the ANDs with the
4531 similar mask and compare the result of the ANDs.
4533 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4534 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4535 are the left and right operands of the comparison, respectively.
4537 If the optimization described above can be done, we return the resulting
4538 tree. Otherwise we return zero. */
4540 static tree
4543 {
4547 tree unsigned_type;
4550 scalar_int_mode nmode;
4555 tree mask;
4556 tree offset;
4558 /* Get all the information about the extractions being done. If the bit size
4559 is the same as the size of the underlying object, we aren't doing an
4560 extraction at all and so can do nothing. We also don't want to
4561 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4562 then will no longer be able to replace it. */
4577 else
4578 {
4579 /* If this is not a constant, we can only do something if bit positions,
4580 sizes, signedness and storage order are the same. */
4581 rinner
4594 }
4596 /* Honor the C++ memory model and mimic what RTL expansion does. */
4600 {
4604 }
4606 /* See if we can find a mode to refer to this field. We should be able to,
4607 but fail if we can't. */
4615 /* Set signed and unsigned types of the precision of this mode for the
4616 shifts below. */
4619 /* Compute the bit position and size for the new reference and our offset
4620 within it. If the new reference is the same size as the original, we
4621 won't optimize anything, so return zero. */
4631 /* Make the mask to be used against the extracted field. */
4638 {
4642 /* If not comparing with constant, just rework the comparison
4643 and return. */
4651 }
4653 /* Otherwise, we are handling the constant case. See if the constant is too
4654 big for the field. Warn and return a tree for 0 (false) if so. We do
4655 this not only for its own sake, but to avoid having to test for this
4656 error case below. If we didn't, we might generate wrong code.
4658 For unsigned fields, the constant shifted right by the field length should
4659 be all zero. For signed fields, the high-order bits should agree with
4660 the sign bit. */
4663 {
4665 {
4669 }
4670 }
4671 else
4672 {
4675 {
4679 }
4680 }
4685 /* Single-bit compares should always be against zero. */
4687 {
4690 }
4692 /* Make a new bitfield reference, shift the constant over the
4693 appropriate number of bits and mask it with the computed mask
4694 (in case this was a signed field). If we changed it, make a new one. */
4702 mask);
4707 }
4708 \f
4709 /* Subroutine for fold_truth_andor_1: decode a field reference.
4711 If EXP is a comparison reference, we return the innermost reference.
4713 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4714 set to the starting bit number.
4716 If the innermost field can be completely contained in a mode-sized
4717 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4719 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4720 otherwise it is not changed.
4722 *PUNSIGNEDP is set to the signedness of the field.
4724 *PREVERSEP is set to the storage order of the field.
4726 *PMASK is set to the mask used. This is either contained in a
4727 BIT_AND_EXPR or derived from the width of the field.
4729 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4731 Return 0 if this is not a component reference or is one that we can't
4732 do anything with. */
4734 static tree
4739 {
4744 tree unsigned_type;
4747 /* All the optimizations using this function assume integer fields.
4748 There are problems with FP fields since the type_for_size call
4749 below can fail for, e.g., XFmode. */
4753 /* We are interested in the bare arrangement of bits, so strip everything
4754 that doesn't affect the machine mode. However, record the type of the
4755 outermost expression if it may matter below. */
4762 {
4768 }
4779 /* Reject out-of-bound accesses (PR79731). */
4791 /* If the number of bits in the reference is the same as the bitsize of
4792 the outer type, then the outer type gives the signedness. Otherwise
4793 (in case of a small bitfield) the signedness is unchanged. */
4797 /* Compute the mask to access the bitfield. */
4805 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4813 }
4815 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4816 bit positions and MASK is SIGNED. */
4818 static bool
4820 {
4824 /* If this function returns true when the type of the mask is
4825 UNSIGNED, then there will be errors. In particular see
4826 gcc.c-torture/execute/990326-1.c. There does not appear to be
4827 any documentation paper trail as to why this is so. But the pre
4828 wide-int worked with that restriction and it has been preserved
4829 here. */
4834 }
4836 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4837 represents the sign bit of EXP's type. If EXP represents a sign
4838 or zero extension, also test VAL against the unextended type.
4839 The return value is the (sub)expression whose sign bit is VAL,
4840 or NULL_TREE otherwise. */
4842 tree
4844 {
4846 tree t;
4848 /* Tree EXP must have an integral type. */
4853 /* Tree VAL must be an integer constant. */
4862 /* Handle extension from a narrower type. */
4868 }
4870 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4871 to be evaluated unconditionally. */
4873 static bool
4875 {
4876 /* Strip any conversions that don't change the machine mode. */
4885 /* Don't regard global variables as simple. They may be
4886 allocated in ways unknown to the compiler (shared memory,
4887 #pragma weak, etc). */
4890 /* Weakrefs are not safe to be read, since they can be NULL.
4891 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4892 have DECL_WEAK flag set. */
4894 /* Loading a static variable is unduly expensive, but global
4895 registers aren't expensive. */
4897 }
4899 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4900 to be evaluated unconditionally.
4901 I addition to simple_operand_p, we assume that comparisons, conversions,
4902 and logic-not operations are simple, if their operands are simple, too. */
4904 static bool
4906 {
4925 }
4927 \f
4928 /* The following functions are subroutines to fold_range_test and allow it to
4929 try to change a logical combination of comparisons into a range test.
4931 For example, both
4932 X == 2 || X == 3 || X == 4 || X == 5
4933 and
4934 X >= 2 && X <= 5
4935 are converted to
4936 (unsigned) (X - 2) <= 3
4938 We describe each set of comparisons as being either inside or outside
4939 a range, using a variable named like IN_P, and then describe the
4940 range with a lower and upper bound. If one of the bounds is omitted,
4941 it represents either the highest or lowest value of the type.
4943 In the comments below, we represent a range by two numbers in brackets
4944 preceded by a "+" to designate being inside that range, or a "-" to
4945 designate being outside that range, so the condition can be inverted by
4946 flipping the prefix. An omitted bound is represented by a "-". For
4947 example, "- [-, 10]" means being outside the range starting at the lowest
4948 possible value and ending at 10, in other words, being greater than 10.
4949 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4950 always false.
4952 We set up things so that the missing bounds are handled in a consistent
4953 manner so neither a missing bound nor "true" and "false" need to be
4954 handled using a special case. */
4956 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4957 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4958 and UPPER1_P are nonzero if the respective argument is an upper bound
4959 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4960 must be specified for a comparison. ARG1 will be converted to ARG0's
4961 type if both are specified. */
4963 static tree
4966 {
4967 tree tem;
4971 /* If neither arg represents infinity, do the normal operation.
4972 Else, if not a comparison, return infinity. Else handle the special
4973 comparison rules. Note that most of the cases below won't occur, but
4974 are handled for consistency. */
4977 {
4982 }
4987 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4988 for neither. In real maths, we cannot assume open ended ranges are
4989 the same. But, this is computer arithmetic, where numbers are finite.
4990 We can therefore make the transformation of any unbounded range with
4991 the value Z, Z being greater than any representable number. This permits
4992 us to treat unbounded ranges as equal. */
4996 {
5017 }
5020 }
5021 \f
5022 /* Helper routine for make_range. Perform one step for it, return
5023 new expression if the loop should continue or NULL_TREE if it should
5024 stop. */
5026 tree
5030 {
5036 {
5038 /* We can only do something if the range is testing for zero. */
5047 /* We can only do something if the range is testing for zero
5048 and if the second operand is an integer constant. Note that
5049 saying something is "in" the range we make is done by
5050 complementing IN_P since it will set in the initial case of
5051 being not equal to zero; "out" is leaving it alone. */
5058 {
5079 }
5081 /* If this is an unsigned comparison, we also know that EXP is
5082 greater than or equal to zero. We base the range tests we make
5083 on that fact, so we record it here so we can parse existing
5084 range tests. We test arg0_type since often the return type
5085 of, e.g. EQ_EXPR, is boolean. */
5087 {
5091 NULL_TREE))
5096 /* If the high bound is missing, but we have a nonzero low
5097 bound, reverse the range so it goes from zero to the low bound
5098 minus 1. */
5100 {
5105 }
5106 }
5114 /* If flag_wrapv and ARG0_TYPE is signed, make sure
5115 low and high are non-NULL, then normalize will DTRT. */
5118 {
5123 }
5125 /* (-x) IN [a,b] -> x in [-b, -a] */
5137 /* ~ X -> -X - 1 */
5146 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
5147 move a constant to the other side. */
5152 /* If EXP is signed, any overflow in the computation is undefined,
5153 so we don't worry about it so long as our computations on
5154 the bounds don't overflow. For unsigned, overflow is defined
5155 and this is exactly the right thing. */
5167 normalize:
5168 /* Check for an unsigned range which has wrapped around the maximum
5169 value thus making n_high < n_low, and normalize it. */
5171 {
5177 /* If the range is of the form +/- [ x+1, x ], we won't
5178 be able to normalize it. But then, it represents the
5179 whole range or the empty set, so make it
5180 +/- [ -, - ]. */
5184 else
5186 }
5187 else
5195 CASE_CONVERT:
5213 /* If we're converting arg0 from an unsigned type, to exp,
5214 a signed type, we will be doing the comparison as unsigned.
5215 The tests above have already verified that LOW and HIGH
5216 are both positive.
5218 So we have to ensure that we will handle large unsigned
5219 values the same way that the current signed bounds treat
5220 negative values. */
5223 {
5224 tree high_positive;
5225 tree equiv_type;
5226 /* For fixed-point modes, we need to pass the saturating flag
5227 as the 2nd parameter. */
5229 equiv_type
5232 else
5233 equiv_type
5236 /* A range without an upper bound is, naturally, unbounded.
5237 Since convert would have cropped a very large value, use
5238 the max value for the destination type. */
5239 high_positive
5246 high_positive),
5249 /* If the low bound is specified, "and" the range with the
5250 range for which the original unsigned value will be
5251 positive. */
5253 {
5256 integer_zero_node),
5257 high_positive))
5261 }
5262 else
5263 {
5264 /* Otherwise, "or" the range with the range of the input
5265 that will be interpreted as negative. */
5268 integer_zero_node),
5269 high_positive))
5273 }
5274 }
5283 }
5284 }
5286 /* Given EXP, a logical expression, set the range it is testing into
5287 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
5288 actually being tested. *PLOW and *PHIGH will be made of the same
5289 type as the returned expression. If EXP is not a comparison, we
5290 will most likely not be returning a useful value and range. Set
5291 *STRICT_OVERFLOW_P to true if the return value is only valid
5292 because signed overflow is undefined; otherwise, do not change
5293 *STRICT_OVERFLOW_P. */
5295 tree
5298 {
5306 /* Start with simply saying "EXP != 0" and then look at the code of EXP
5307 and see if we can refine the range. Some of the cases below may not
5308 happen, but it doesn't seem worth worrying about this. We "continue"
5309 the outer loop when we've changed something; otherwise we "break"
5310 the switch, which will "break" the while. */
5316 {
5322 {
5330 }
5339 }
5341 /* If EXP is a constant, we can evaluate whether this is true or false. */
5343 {
5350 }
5354 }
5356 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
5357 a bitwise check i.e. when
5358 LOW == 0xXX...X00...0
5359 HIGH == 0xXX...X11...1
5360 Return corresponding mask in MASK and stem in VALUE. */
5362 static bool
5365 {
5388 }
5389 \f
5390 /* Helper routine for build_range_check and match.pd. Return the type to
5391 perform the check or NULL if it shouldn't be optimized. */
5393 tree
5395 {
5396 /* First make sure that arithmetics in this type is valid, then make sure
5397 that it wraps around. */
5402 {
5405 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5406 for the type in question, as we rely on this here. */
5416 else
5418 }
5422 }
5424 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
5425 type, TYPE, return an expression to test if EXP is in (or out of, depending
5426 on IN_P) the range. Return 0 if the test couldn't be created. */
5428 tree
5431 {
5434 /* Disable this optimization for function pointer expressions
5435 on targets that require function pointer canonicalization. */
5442 {
5448 }
5470 value);
5473 {
5475 {
5479 }
5481 }
5483 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5485 {
5489 {
5491 {
5494 etype
5496 else
5499 }
5502 }
5503 }
5505 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5506 This requires wrap-around arithmetics for the type of the expression. */
5523 }
5524 \f
5525 /* Return the predecessor of VAL in its type, handling the infinite case. */
5527 static tree
5529 {
5535 else
5538 }
5540 /* Return the successor of VAL in its type, handling the infinite case. */
5542 static tree
5544 {
5550 else
5553 }
5555 /* Given two ranges, see if we can merge them into one. Return 1 if we
5556 can, 0 if we can't. Set the output range into the specified parameters. */
5558 bool
5561 {
5565 tree tem;
5575 /* Make range 0 be the range that starts first, or ends last if they
5576 start at the same value. Swap them if it isn't. */
5579 || (lowequal
5582 {
5586 }
5588 /* If the second range is != high1 where high1 is the type maximum of
5589 the type, try first merging with < high1 range. */
5591 && high1
5598 {
5603 /* Similarly for the second range != low1 where low1 is the type minimum
5604 of the type, try first merging with > low1 range. */
5609 }
5611 /* Now flag two cases, whether the ranges are disjoint or whether the
5612 second range is totally subsumed in the first. Note that the tests
5613 below are simplified by the ones above. */
5619 /* We now have four cases, depending on whether we are including or
5620 excluding the two ranges. */
5622 {
5623 /* If they don't overlap, the result is false. If the second range
5624 is a subset it is the result. Otherwise, the range is from the start
5625 of the second to the end of the first. */
5630 else
5632 }
5635 {
5636 /* If they don't overlap, the result is the first range. If they are
5637 equal, the result is false. If the second range is a subset of the
5638 first, and the ranges begin at the same place, we go from just after
5639 the end of the second range to the end of the first. If the second
5640 range is not a subset of the first, or if it is a subset and both
5641 ranges end at the same place, the range starts at the start of the
5642 first range and ends just before the second range.
5643 Otherwise, we can't describe this as a single range. */
5649 {
5654 {
5655 /* We are in the weird situation where high0 > high1 but
5656 high1 has no successor. Punt. */
5658 }
5659 }
5661 {
5666 {
5667 /* low0 < low1 but low1 has no predecessor. Punt. */
5669 }
5670 }
5671 else
5673 }
5676 {
5677 /* If they don't overlap, the result is the second range. If the second
5678 is a subset of the first, the result is false. Otherwise,
5679 the range starts just after the first range and ends at the
5680 end of the second. */
5685 else
5686 {
5691 {
5692 /* high1 > high0 but high0 has no successor. Punt. */
5694 }
5695 }
5696 }
5698 else
5699 {
5700 /* The case where we are excluding both ranges. Here the complex case
5701 is if they don't overlap. In that case, the only time we have a
5702 range is if they are adjacent. If the second is a subset of the
5703 first, the result is the first. Otherwise, the range to exclude
5704 starts at the beginning of the first range and ends at the end of the
5705 second. */
5707 {
5712 else
5713 {
5714 /* Canonicalize - [min, x] into - [-, x]. */
5717 {
5720 GET_MODE_BITSIZE
5723 /* FALLTHROUGH */
5736 }
5738 /* Canonicalize - [x, max] into - [x, -]. */
5741 {
5744 GET_MODE_BITSIZE
5747 /* FALLTHROUGH */
5763 }
5765 /* The ranges might be also adjacent between the maximum and
5766 minimum values of the given type. For
5767 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5768 return + [x + 1, y - 1]. */
5770 {
5777 }
5778 else
5780 }
5781 }
5784 else
5786 }
5790 }
5791 \f
5793 /* Subroutine of fold, looking inside expressions of the form
5794 A op B ? A : C, where (ARG00, COMP_CODE, ARG01), ARG1 and ARG2
5795 are the three operands of the COND_EXPR. This function is
5796 being used also to optimize A op B ? C : A, by reversing the
5797 comparison first.
5799 Return a folded expression whose code is not a COND_EXPR
5800 anymore, or NULL_TREE if no folding opportunity is found. */
5802 static tree
5806 {
5808 tree tem;
5813 /* If we have A op 0 ? A : -A, consider applying the following
5814 transformations:
5816 A == 0? A : -A same as -A
5817 A != 0? A : -A same as A
5818 A >= 0? A : -A same as abs (A)
5819 A > 0? A : -A same as abs (A)
5820 A <= 0? A : -A same as -abs (A)
5821 A < 0? A : -A same as -abs (A)
5823 None of these transformations work for modes with signed
5824 zeros. If A is +/-0, the first two transformations will
5825 change the sign of the result (from +0 to -0, or vice
5826 versa). The last four will fix the sign of the result,
5827 even though the original expressions could be positive or
5828 negative, depending on the sign of A.
5830 Note that all these transformations are correct if A is
5831 NaN, since the two alternatives (A and -A) are also NaNs. */
5838 /* In the case that A is of the form X-Y, '-A' (arg2) may
5839 have already been folded to Y-X, check for that. */
5847 {
5859 /* Fall through. */
5870 /* FALLTHRU */
5877 {
5878 /* A <= 0 ? A : -A for A INT_MIN is valid, but -abs(INT_MIN)
5879 is not, invokes UB both in abs and in the negation of it.
5880 So, use ABSU_EXPR instead. */
5885 }
5886 else
5887 {
5890 }
5894 }
5896 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5897 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5898 both transformations are correct when A is NaN: A != 0
5899 is then true, and A == 0 is false. */
5903 {
5908 }
5910 /* Try some transformations of A op B ? A : B.
5912 A == B? A : B same as B
5913 A != B? A : B same as A
5914 A >= B? A : B same as max (A, B)
5915 A > B? A : B same as max (B, A)
5916 A <= B? A : B same as min (A, B)
5917 A < B? A : B same as min (B, A)
5919 As above, these transformations don't work in the presence
5920 of signed zeros. For example, if A and B are zeros of
5921 opposite sign, the first two transformations will change
5922 the sign of the result. In the last four, the original
5923 expressions give different results for (A=+0, B=-0) and
5924 (A=-0, B=+0), but the transformed expressions do not.
5926 The first two transformations are correct if either A or B
5927 is a NaN. In the first transformation, the condition will
5928 be false, and B will indeed be chosen. In the case of the
5929 second transformation, the condition A != B will be true,
5930 and A will be chosen.
5932 The conversions to max() and min() are not correct if B is
5933 a number and A is not. The conditions in the original
5934 expressions will be false, so all four give B. The min()
5935 and max() versions would give a NaN instead. */
5938 /* Avoid these transformations if the COND_EXPR may be used
5939 as an lvalue in the C++ front-end. PR c++/19199. */
5940 && (in_gimple_form
5946 {
5952 {
5961 /* In C++ a ?: expression can be an lvalue, so put the
5962 operand which will be used if they are equal first
5963 so that we can convert this back to the
5964 corresponding COND_EXPR. */
5966 {
5974 }
5981 {
5989 }
6002 }
6003 }
6006 }
6009 \f
6010 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
6011 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
6012 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
6013 false) >= 2)
6014 #endif
6016 /* EXP is some logical combination of boolean tests. See if we can
6017 merge it into some range test. Return the new tree if so. */
6019 static tree
6022 {
6036 /* If op0 is known true or false and this is a short-circuiting
6037 operation we must not merge with op1 since that makes side-effects
6038 unconditional. So special-case this. */
6045 /* If this is an OR operation, invert both sides; we will invert
6046 again at the end. */
6050 /* If both expressions are the same, if we can merge the ranges, and we
6051 can build the range test, return it or it inverted. If one of the
6052 ranges is always true or always false, consider it to be the same
6053 expression as the other. */
6061 {
6065 }
6067 /* On machines where the branch cost is expensive, if this is a
6068 short-circuited branch and the underlying object on both sides
6069 is the same, make a non-short-circuit operation. */
6072 logical_op_non_short_circuit
6079 {
6080 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
6081 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
6082 which cases we can't do this. */
6090 {
6099 {
6102 WARN_STRICT_OVERFLOW_COMPARISON);
6106 }
6107 }
6108 }
6111 }
6112 \f
6113 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
6114 bit value. Arrange things so the extra bits will be set to zero if and
6115 only if C is signed-extended to its full width. If MASK is nonzero,
6116 it is an INTEGER_CST that should be AND'ed with the extra bits. */
6118 static tree
6120 {
6123 tree temp;
6128 /* We work by getting just the sign bit into the low-order bit, then
6129 into the high-order bit, then sign-extend. We then XOR that value
6130 with C. */
6134 /* We must use a signed type in order to get an arithmetic right shift.
6135 However, we must also avoid introducing accidental overflows, so that
6136 a subsequent call to integer_zerop will work. Hence we must
6137 do the type conversion here. At this point, the constant is either
6138 zero or one, and the conversion to a signed type can never overflow.
6139 We could get an overflow if this conversion is done anywhere else. */
6148 /* If necessary, convert the type back to match the type of C. */
6153 }
6154 \f
6155 /* For an expression that has the form
6156 (A && B) || ~B
6157 or
6158 (A || B) && ~B,
6159 we can drop one of the inner expressions and simplify to
6160 A || ~B
6161 or
6162 A && ~B
6163 LOC is the location of the resulting expression. OP is the inner
6164 logical operation; the left-hand side in the examples above, while CMPOP
6165 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
6166 removing a condition that guards another, as in
6167 (A != NULL && A->...) || A == NULL
6168 which we must not transform. If RHS_ONLY is true, only eliminate the
6169 right-most operand of the inner logical operation. */
6171 static tree
6174 {
6192 {
6195 {
6198 }
6199 }
6201 {
6204 {
6207 }
6208 }
6223 }
6225 /* Find ways of folding logical expressions of LHS and RHS:
6226 Try to merge two comparisons to the same innermost item.
6227 Look for range tests like "ch >= '0' && ch <= '9'".
6228 Look for combinations of simple terms on machines with expensive branches
6229 and evaluate the RHS unconditionally.
6231 For example, if we have p->a == 2 && p->b == 4 and we can make an
6232 object large enough to span both A and B, we can do this with a comparison
6233 against the object ANDed with the a mask.
6235 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
6236 operations to do this with one comparison.
6238 We check for both normal comparisons and the BIT_AND_EXPRs made this by
6239 function and the one above.
6241 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
6242 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
6244 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
6245 two operands.
6247 We return the simplified tree or 0 if no optimization is possible. */
6249 static tree
6252 {
6253 /* If this is the "or" of two comparisons, we can do something if
6254 the comparisons are NE_EXPR. If this is the "and", we can do something
6255 if the comparisons are EQ_EXPR. I.e.,
6256 (a->b == 2 && a->c == 4) can become (a->new == NEW).
6258 WANTED_CODE is this operation code. For single bit fields, we can
6259 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
6260 comparison for one-bit fields. */
6281 /* Start by getting the comparison codes. Fail if anything is volatile.
6282 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
6283 it were surrounded with a NE_EXPR. */
6292 {
6296 }
6299 {
6303 }
6314 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
6317 {
6320 {
6325 }
6328 {
6334 }
6335 }
6340 /* If the RHS can be evaluated unconditionally and its operands are
6341 simple, it wins to evaluate the RHS unconditionally on machines
6342 with expensive branches. In this case, this isn't a comparison
6343 that can be merged. */
6350 {
6351 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
6362 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
6372 }
6374 /* See if the comparisons can be merged. Then get all the parameters for
6375 each side. */
6400 /* It must be true that the inner operation on the lhs of each
6401 comparison must be the same if we are to be able to do anything.
6402 Then see if we have constants. If not, the same must be true for
6403 the rhs's. */
6412 {
6415 }
6420 else
6423 /* If either comparison code is not correct for our logical operation,
6424 fail. However, we can convert a one-bit comparison against zero into
6425 the opposite comparison against that bit being set in the field. */
6429 {
6431 {
6432 /* Make the left operand unsigned, since we are only interested
6433 in the value of one bit. Otherwise we are doing the wrong
6434 thing below. */
6437 }
6438 else
6440 }
6442 /* This is analogous to the code for l_const above. */
6444 {
6446 {
6449 }
6450 else
6452 }
6454 /* See if we can find a mode that contains both fields being compared on
6455 the left. If we can't, fail. Otherwise, update all constants and masks
6456 to be relative to a field of that size. */
6470 {
6473 }
6483 {
6492 {
6496 }
6497 }
6499 {
6508 {
6512 }
6513 }
6515 /* If the right sides are not constant, do the same for it. Also,
6516 disallow this optimization if a size, signedness or storage order
6517 mismatch occurs between the left and right sides. */
6519 {
6523 /* Make sure the two fields on the right
6524 correspond to the left without being swapped. */
6541 {
6544 }
6555 /* Make a mask that corresponds to both fields being compared.
6556 Do this for both items being compared. If the operands are the
6557 same size and the bits being compared are in the same position
6558 then we can do this by masking both and comparing the masked
6559 results. */
6566 {
6580 }
6582 /* There is still another way we can do something: If both pairs of
6583 fields being compared are adjacent, we may be able to make a wider
6584 field containing them both.
6586 Note that we still must mask the lhs/rhs expressions. Furthermore,
6587 the mask must be shifted to account for the shift done by
6588 make_bit_field_ref. */
6597 {
6598 tree type;
6616 /* Convert to the smaller type before masking out unwanted bits. */
6619 {
6621 {
6625 }
6627 {
6631 }
6632 }
6641 }
6644 }
6646 /* Handle the case of comparisons with constants. If there is something in
6647 common between the masks, those bits of the constants must be the same.
6648 If not, the condition is always false. Test for this to avoid generating
6649 incorrect code below. */
6654 {
6656 {
6659 }
6660 else
6661 {
6664 }
6665 }
6670 /* Construct the expression we will return. First get the component
6671 reference we will make. Unless the mask is all ones the width of
6672 that field, perform the mask operation. Then compare with the
6673 merged constant. */
6684 }
6685 \f
6686 /* T is an integer expression that is being multiplied, divided, or taken a
6687 modulus (CODE says which and what kind of divide or modulus) by a
6688 constant C. See if we can eliminate that operation by folding it with
6689 other operations already in T. WIDE_TYPE, if non-null, is a type that
6690 should be used for the computation if wider than our type.
6692 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6693 (X * 2) + (Y * 4). We must, however, be assured that either the original
6694 expression would not overflow or that overflow is undefined for the type
6695 in the language in question.
6697 If we return a non-null expression, it is an equivalent form of the
6698 original computation, but need not be in the original type.
6700 We set *STRICT_OVERFLOW_P to true if the return values depends on
6701 signed overflow being undefined. Otherwise we do not change
6702 *STRICT_OVERFLOW_P. */
6704 static tree
6707 {
6708 /* To avoid exponential search depth, refuse to allow recursion past
6709 three levels. Beyond that (1) it's highly unlikely that we'll find
6710 something interesting and (2) we've probably processed it before
6711 when we built the inner expression. */
6714 tree ret;
6719 depth++;
6721 depth--;
6724 }
6726 static tree
6729 {
6741 /* Don't deal with constants of zero here; they confuse the code below. */
6751 /* Note that we need not handle conditional operations here since fold
6752 already handles those cases. So just do arithmetic here. */
6754 {
6756 /* For a constant, we can always simplify if we are a multiply
6757 or (for divide and modulus) if it is a multiple of our constant. */
6761 {
6764 /* If the multiplication overflowed, we lost information on it.
6765 See PR68142 and PR69845. */
6769 }
6775 /* If op0 is an expression ... */
6781 /* ... and has wrapping overflow, and its type is smaller
6782 than ctype, then we cannot pass through as widening. */
6786 /* ... or this is a truncation (t is narrower than op0),
6787 then we cannot pass through this narrowing. */
6790 /* ... or signedness changes for division or modulus,
6791 then we cannot pass through this conversion. */
6795 /* ... or has undefined overflow while the converted to
6796 type has not, we cannot do the operation in the inner type
6797 as that would introduce undefined overflow. */
6802 /* Pass the constant down and see if we can make a simplification. If
6803 we can, replace this expression with the inner simplification for
6804 possible later conversion to our or some other type. */
6815 /* If widening the type changes it from signed to unsigned, then we
6816 must avoid building ABS_EXPR itself as unsigned. */
6818 {
6822 {
6825 }
6827 }
6828 /* If the constant is negative, we cannot simplify this. */
6831 /* FALLTHROUGH */
6833 /* For division and modulus, type can't be unsigned, as e.g.
6834 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6835 For signed types, even with wrapping overflow, this is fine. */
6844 /* If widening the type changes the signedness, then we can't perform
6845 this optimization as that changes the result. */
6849 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6855 {
6862 }
6866 /* If the second operand is constant, this is a multiplication
6867 or floor division, by a power of two, so we can treat it that
6868 way unless the multiplier or divisor overflows. Signed
6869 left-shift overflow is implementation-defined rather than
6870 undefined in C90, so do not convert signed left shift into
6871 multiplication. */
6874 /* const_binop may not detect overflow correctly,
6875 so check for it explicitly here. */
6884 ctype,
6886 t1),
6891 /* See if we can eliminate the operation on both sides. If we can, we
6892 can return a new PLUS or MINUS. If we can't, the only remaining
6893 cases where we can do anything are if the second operand is a
6894 constant. */
6901 /* If not multiplication, we can only do this if both operands
6902 are divisible by c. */
6905 {
6910 }
6912 /* If this was a subtraction, negate OP1 and set it to be an addition.
6913 This simplifies the logic below. */
6915 {
6917 /* If OP1 was not easily negatable, the constant may be OP0. */
6919 {
6922 }
6923 }
6928 /* If either OP1 or C are negative, this optimization is not safe for
6929 some of the division and remainder types while for others we need
6930 to change the code. */
6932 {
6940 }
6942 /* If it's a multiply or a division/modulus operation of a multiple
6943 of our constant, do the operation and verify it doesn't overflow. */
6947 {
6950 /* We allow the constant to overflow with wrapping semantics. */
6954 }
6955 else
6958 /* If we have an unsigned type, we cannot widen the operation since it
6959 will change the result if the original computation overflowed. */
6963 /* The last case is if we are a multiply. In that case, we can
6964 apply the distributive law to commute the multiply and addition
6965 if the multiplication of the constants doesn't overflow
6966 and overflow is defined. With undefined overflow
6967 op0 * c might overflow, while (op0 + orig_op1) * c doesn't.
6968 But fold_plusminus_mult_expr would factor back any power-of-two
6969 value so do not distribute in the first place in this case. */
6977 op1);
6982 /* We have a special case here if we are doing something like
6983 (C * 8) % 4 since we know that's zero. */
6986 /* If the multiplication can overflow we cannot optimize this. */
6991 {
6994 }
6996 /* ... fall through ... */
7000 /* If we can extract our operation from the LHS, do so and return a
7001 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
7002 do something only if the second operand is a constant. */
7018 /* If these are the same operation types, we can associate them
7019 assuming no overflow. */
7021 {
7036 }
7038 /* If these operations "cancel" each other, we have the main
7039 optimizations of this pass, which occur when either constant is a
7040 multiple of the other, in which case we replace this with either an
7041 operation or CODE or TCODE.
7043 If we have an unsigned type, we cannot do this since it will change
7044 the result if the original computation overflowed. */
7051 {
7054 {
7061 }
7064 {
7071 }
7072 }
7077 }
7080 }
7081 \f
7082 /* Return a node which has the indicated constant VALUE (either 0 or
7083 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
7084 and is of the indicated TYPE. */
7086 tree
7088 {
7097 else
7099 }
7102 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
7103 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
7104 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
7105 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
7106 COND is the first argument to CODE; otherwise (as in the example
7107 given here), it is the second argument. TYPE is the type of the
7108 original expression. Return NULL_TREE if no simplification is
7109 possible. */
7111 static tree
7116 {
7124 /* Do not move possibly trapping operations into the conditional as this
7125 pessimizes code and causes gimplification issues when applied late. */
7133 {
7137 /* If this operand throws an expression, then it does not make
7138 sense to try to perform a logical or arithmetic operation
7139 involving it. */
7144 }
7147 {
7152 }
7153 else
7154 /* Detect the case of mixing vector and scalar types - bail out. */
7160 /* This transformation is only worthwhile if we don't have to wrap ARG
7161 in a SAVE_EXPR and the operation can be simplified without recursing
7162 on at least one of the branches once its pushed inside the COND_EXPR. */
7171 {
7175 else
7177 }
7179 {
7183 else
7185 }
7187 /* Check that we have simplified at least one of the branches. */
7192 }
7194 \f
7195 /* Subroutine of fold() that checks for the addition of ARG +/- 0.0.
7197 If !NEGATE, return true if ZERO_ARG is +/-0.0 and, for all ARG of
7198 type TYPE, ARG + ZERO_ARG is the same as ARG. If NEGATE, return true
7199 if ARG - ZERO_ARG is the same as X.
7201 If ARG is NULL, check for any value of type TYPE.
7203 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
7204 and finite. The problematic cases are when X is zero, and its mode
7205 has signed zeros. In the case of rounding towards -infinity,
7206 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
7207 modes, X + 0 is not the same as X because -0 + 0 is 0. */
7209 bool
7212 {
7216 /* Don't allow the fold with -fsignaling-nans. */
7220 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
7224 /* There is no case that is safe for all rounding modes. */
7228 /* In a vector or complex, we would need to check the sign of all zeros. */
7234 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
7238 /* The mode has signed zeros, and we have to honor their sign.
7239 In this situation, there are only two cases we can return true for.
7240 (i) X - 0 is the same as X with default rounding.
7241 (ii) X + 0 is X when X can't possibly be -0.0. */
7243 }
7245 /* Subroutine of match.pd that optimizes comparisons of a division by
7246 a nonzero integer constant against an integer constant, i.e.
7247 X/C1 op C2.
7249 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7250 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
7252 enum tree_code
7255 {
7260 /* We have to do this the hard way to detect unsigned overflow.
7261 prod = int_const_binop (MULT_EXPR, c1, c2); */
7267 {
7271 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
7274 }
7276 {
7279 {
7298 }
7299 }
7300 else
7301 {
7302 /* A negative divisor reverses the relational operators. */
7307 {
7326 }
7327 }
7340 }
7343 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7344 equality/inequality test, then return a simplified form of the test
7345 using a sign testing. Otherwise return NULL. TYPE is the desired
7346 result type. */
7348 static tree
7351 tree result_type)
7352 {
7353 /* If this is testing a single bit, we can optimize the test. */
7357 {
7358 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7359 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7363 /* This is only a win if casting to a signed type is cheap,
7364 i.e. when arg00's type is not a partial mode. */
7366 {
7369 result_type,
7372 }
7373 }
7376 }
7378 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7379 equality/inequality test, then return a simplified form of
7380 the test using shifts and logical operations. Otherwise return
7381 NULL. TYPE is the desired result type. */
7383 tree
7386 {
7387 /* If this is testing a single bit, we can optimize the test. */
7391 {
7400 /* First, see if we can fold the single bit test into a sign-bit
7401 test. */
7403 result_type);
7407 /* Otherwise we have (A & C) != 0 where C is a single bit,
7408 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7409 Similarly for (A & C) == 0. */
7411 /* If INNER is a right shift of a constant and it plus BITNUM does
7412 not overflow, adjust BITNUM and INNER. */
7418 {
7421 }
7423 /* If we are going to be able to omit the AND below, we must do our
7424 operations as unsigned. If we must use the AND, we have a choice.
7425 Normally unsigned is faster, but for some machines signed is. */
7443 /* Put the AND last so it can combine with more things. */
7446 /* Make sure to return the proper type. */
7450 }
7452 }
7454 /* Test whether it is preferable to swap two operands, ARG0 and
7455 ARG1, for example because ARG0 is an integer constant and ARG1
7456 isn't. */
7458 bool
7460 {
7474 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7475 for commutative and comparison operators. Ensuring a canonical
7476 form allows the optimizers to find additional redundancies without
7477 having to explicitly check for both orderings. */
7483 /* Put SSA_NAMEs last. */
7489 /* Put variables last. */
7496 }
7499 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7500 means A >= Y && A != MAX, but in this case we know that
7501 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7503 static tree
7505 {
7512 else
7521 {
7524 }
7526 {
7529 }
7530 else
7537 {
7538 /* Convert the pointer types into integer before taking the difference. */
7542 }
7543 else
7550 }
7552 /* Fold a sum or difference of at least one multiplication.
7553 Returns the folded tree or NULL if no simplification could be made. */
7555 static tree
7558 {
7562 /* (A * C) +- (B * C) -> (A+-B) * C.
7563 (A * C) +- A -> A * (C+-1).
7564 We are most concerned about the case where C is a constant,
7565 but other combinations show up during loop reduction. Since
7566 it is not difficult, try all four possibilities. */
7569 {
7572 }
7574 {
7577 }
7578 else
7579 {
7580 /* We cannot generate constant 1 for fract. */
7585 }
7587 {
7590 }
7592 {
7594 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7595 the purpose of this canonicalization. */
7599 {
7602 }
7603 else
7605 }
7606 else
7607 {
7608 /* We cannot generate constant 1 for fract. */
7613 }
7616 /* Prefer factoring a common non-constant. */
7626 /* No identical multiplicands; see if we can find a common
7627 power-of-two factor in non-power-of-two multiplies. This
7628 can help in multi-dimensional array access. */
7630 {
7633 HOST_WIDE_INT tmp;
7635 tree maybe_same;
7637 /* Move min of absolute values to int11. */
7639 {
7644 }
7645 else
7652 /* The remainder should not be a constant, otherwise we
7653 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7654 increased the number of multiplications necessary. */
7656 {
7664 }
7665 }
7672 /* We are neither factoring zero nor minus one. */
7680 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7681 same may be minus one and thus the multiplication may overflow. Perform
7682 the sum operation in an unsigned type. */
7687 /* If the sum evaluated to a constant that is not -INF the multiplication
7688 cannot overflow. */
7695 /* Do not resort to unsigned multiplication because
7696 we lose the no-overflow property of the expression. */
7698 }
7700 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7701 specified by EXPR into the buffer PTR of length LEN bytes.
7702 Return the number of bytes placed in the buffer, or zero
7703 upon failure. */
7705 static int
7707 {
7719 /* Dry run. */
7725 {
7727 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7728 number of bytes. */
7732 {
7739 else
7741 }
7742 else
7746 }
7748 }
7751 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7752 specified by EXPR into the buffer PTR of length LEN bytes.
7753 Return the number of bytes placed in the buffer, or zero
7754 upon failure. */
7756 static int
7758 {
7762 FIXED_VALUE_TYPE value;
7777 }
7780 /* Subroutine of native_encode_expr. Encode the REAL_CST
7781 specified by EXPR into the buffer PTR of length LEN bytes.
7782 Return the number of bytes placed in the buffer, or zero
7783 upon failure. */
7785 static int
7787 {
7793 /* There are always 32 bits in each long, no matter the size of
7794 the hosts long. We handle floating point representations with
7795 up to 192 bits. */
7804 /* Dry run. */
7813 {
7818 {
7825 else
7827 }
7828 else
7829 {
7832 {
7833 /* Reverse bytes within each long, or within the entire float
7834 if it's smaller than a long (for HFmode). */
7837 }
7838 }
7843 }
7845 }
7847 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7848 specified by EXPR into the buffer PTR of length LEN bytes.
7849 Return the number of bytes placed in the buffer, or zero
7850 upon failure. */
7852 static int
7854 {
7856 tree part;
7870 }
7872 /* Like native_encode_vector, but only encode the first COUNT elements.
7873 The other arguments are as for native_encode_vector. */
7875 static int
7878 {
7882 {
7883 /* This is the only case in which elements can be smaller than a byte.
7884 Element 0 is always in the lsb of the containing byte. */
7893 /* Zero the buffer and then set bits later where necessary. */
7902 {
7908 {
7911 }
7912 }
7914 }
7919 {
7921 {
7924 }
7935 }
7937 }
7939 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7940 specified by EXPR into the buffer PTR of length LEN bytes.
7941 Return the number of bytes placed in the buffer, or zero
7942 upon failure. */
7944 static int
7946 {
7951 }
7954 /* Subroutine of native_encode_expr. Encode the STRING_CST
7955 specified by EXPR into the buffer PTR of length LEN bytes.
7956 Return the number of bytes placed in the buffer, or zero
7957 upon failure. */
7959 static int
7961 {
7964 /* Wide-char strings are encoded in target byte-order so native
7965 encoding them is trivial. */
7980 else
7981 {
7984 {
7987 }
7989 }
7991 }
7994 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST, REAL_CST,
7995 FIXED_CST, COMPLEX_CST, STRING_CST, or VECTOR_CST specified by EXPR into
7996 the buffer PTR of size LEN bytes. If PTR is NULL, don't actually store
7997 anything, just do a dry run. Fail either if OFF is -1 and LEN isn't
7998 sufficient to encode the entire EXPR, or if OFF is out of bounds.
7999 Otherwise, start at byte offset OFF and encode at most LEN bytes.
8000 Return the number of bytes placed in the buffer, or zero upon failure. */
8002 int
8004 {
8005 /* We don't support starting at negative offset and -1 is special. */
8010 {
8031 }
8032 }
8034 /* Try to find a type whose byte size is smaller or equal to LEN bytes larger
8035 or equal to FIELDSIZE bytes, with underlying mode precision/size multiple
8036 of BITS_PER_UNIT. As native_{interpret,encode}_int works in term of
8037 machine modes, we can't just use build_nonstandard_integer_type. */
8039 tree
8041 {
8042 machine_mode mode;
8044 {
8051 {
8055 }
8056 }
8062 {
8070 }
8073 }
8075 /* Similar to native_encode_expr, but also handle CONSTRUCTORs, VCEs,
8076 NON_LVALUE_EXPRs and nops. If MASK is non-NULL (then PTR has
8077 to be non-NULL and OFF zero), then in addition to filling the
8078 bytes pointed by PTR with the value also clear any bits pointed
8079 by MASK that are known to be initialized, keep them as is for
8080 e.g. uninitialized padding bits or uninitialized fields. */
8082 int
8085 {
8088 /* We don't support starting at negative offset and -1 is special. */
8096 {
8100 mask);
8115 {
8116 tree min_index;
8134 {
8139 {
8142 }
8147 else
8151 {
8155 offset_int wpos
8163 offset_int wcount
8170 }
8172 {
8175 offset_int wpos
8183 }
8186 {
8188 {
8199 }
8201 {
8205 }
8206 }
8210 do
8211 {
8216 {
8218 {
8221 fieldsize);
8224 }
8226 ptr
8229 fieldsize,
8232 mask
8236 else
8237 {
8240 }
8241 }
8244 {
8245 /* Partial overlap. */
8251 {
8255 fieldsize);
8256 }
8257 else
8258 {
8262 }
8265 }
8267 }
8269 }
8271 }
8274 {
8284 {
8290 {
8293 }
8296 {
8305 }
8309 else
8313 {
8314 tree fld;
8316 {
8329 }
8331 {
8335 }
8338 {
8339 cnt--;
8345 }
8346 }
8351 {
8364 {
8369 }
8370 }
8371 else
8372 {
8377 }
8382 {
8389 else
8395 }
8404 {
8405 /* FIXME: Handle PDP endian. */
8416 {
8419 }
8420 else
8421 {
8429 else
8430 {
8433 }
8434 }
8444 else
8457 /* If the bitfield does not start at byte boundary, handle
8458 the partial byte at the start. */
8461 {
8463 {
8468 {
8471 else
8473 }
8474 }
8475 else
8476 {
8481 {
8484 else
8488 }
8489 }
8490 }
8491 /* If the bitfield does not end at byte boundary, handle
8492 the partial byte at the end. */
8496 {
8498 {
8505 }
8506 else
8507 {
8514 }
8515 }
8519 {
8524 }
8525 else
8526 {
8527 /* Partial overlap. */
8531 {
8534 }
8538 }
8540 }
8545 {
8548 {
8551 {
8555 }
8558 }
8561 fldsize,
8571 }
8572 else
8573 {
8574 /* Partial overlap. */
8580 {
8584 fieldsize);
8585 }
8586 else
8587 {
8591 }
8594 }
8595 }
8597 }
8599 }
8600 }
8603 /* Subroutine of native_interpret_expr. Interpret the contents of
8604 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8605 If the buffer cannot be interpreted, return NULL_TREE. */
8607 static tree
8609 {
8619 }
8622 /* Subroutine of native_interpret_expr. Interpret the contents of
8623 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
8624 If the buffer cannot be interpreted, return NULL_TREE. */
8626 static tree
8628 {
8631 double_int result;
8632 FIXED_VALUE_TYPE fixed_value;
8642 }
8645 /* Subroutine of native_interpret_expr. Interpret the contents of
8646 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8647 If the buffer cannot be interpreted, return NULL_TREE. */
8649 tree
8651 {
8655 /* There are always 32 bits in each long, no matter the size of
8656 the hosts long. We handle floating point representations with
8657 up to 192 bits. */
8658 REAL_VALUE_TYPE r;
8668 {
8669 /* Both OFFSET and BYTE index within a long;
8670 bitpos indexes the whole float. */
8673 {
8680 else
8682 }
8683 else
8684 {
8687 {
8688 /* Reverse bytes within each long, or within the entire float
8689 if it's smaller than a long (for HFmode). */
8692 }
8693 }
8697 }
8701 }
8704 /* Subroutine of native_interpret_expr. Interpret the contents of
8705 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8706 If the buffer cannot be interpreted, return NULL_TREE. */
8708 static tree
8710 {
8725 }
8727 /* Read a vector of type TYPE from the target memory image given by BYTES,
8728 which contains LEN bytes. The vector is known to be encodable using
8729 NPATTERNS interleaved patterns with NELTS_PER_PATTERN elements each.
8731 Return the vector on success, otherwise return null. */
8733 static tree
8737 {
8741 {
8742 /* This is the only case in which elements can be smaller than a byte.
8743 Element 0 is always in the lsb of the containing byte. */
8750 {
8757 }
8759 }
8767 {
8773 }
8775 }
8777 /* Subroutine of native_interpret_expr. Interpret the contents of
8778 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8779 If the buffer cannot be interpreted, return NULL_TREE. */
8781 static tree
8783 {
8784 tree etype;
8795 }
8798 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8799 the buffer PTR of length LEN as a constant of type TYPE. For
8800 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8801 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8802 return NULL_TREE. */
8804 tree
8806 {
8808 {
8819 {
8820 /* For floating point values in composite modes, punt if this
8821 folding doesn't preserve bit representation. As the mode doesn't
8822 have fixed precision while GCC pretends it does, there could be
8823 valid values that GCC can't really represent accurately.
8824 See PR95450. Even for other modes, e.g. x86 XFmode can have some
8825 bit combinationations which GCC doesn't preserve. */
8833 }
8847 }
8848 }
8850 /* Returns true if we can interpret the contents of a native encoding
8851 as TYPE. */
8853 bool
8855 {
8857 {
8871 }
8872 }
8874 /* Attempt to interpret aggregate of TYPE from bytes encoded in target
8875 byte order at PTR + OFF with LEN bytes. Does not handle unions. */
8877 tree
8880 {
8883 {
8890 {
8894 }
8899 {
8904 {
8909 }
8913 eltsz);
8917 }
8919 }
8923 {
8931 {
8934 {
8935 poly_int64 bitoffset;
8940 else
8950 }
8951 else
8952 {
8970 HOST_WIDE_INT rpos;
8973 else
8974 {
8977 }
8986 }
8987 }
8990 {
9000 }
9004 {
9009 }
9016 {
9020 /* FIXME: Figure out how to handle PDP endian bitfields. */
9026 else
9030 }
9032 }
9034 }
9036 /* Routines for manipulation of native_encode_expr encoded data if the encoded
9037 or extracted constant positions and/or sizes aren't byte aligned. */
9039 /* Shift left the bytes in PTR of SZ elements by AMNT bits, carrying over the
9040 bits between adjacent elements. AMNT should be within
9041 [0, BITS_PER_UNIT).
9042 Example, AMNT = 2:
9043 00011111|11100000 << 2 = 01111111|10000000
9044 PTR[1] | PTR[0] PTR[1] | PTR[0]. */
9046 void
9049 {
9058 {
9064 {
9067 }
9068 }
9069 }
9071 /* Like shift_bytes_in_array_left but for big-endian.
9072 Shift right the bytes in PTR of SZ elements by AMNT bits, carrying over the
9073 bits between adjacent elements. AMNT should be within
9074 [0, BITS_PER_UNIT).
9075 Example, AMNT = 2:
9076 00011111|11100000 >> 2 = 00000111|11111000
9077 PTR[0] | PTR[1] PTR[0] | PTR[1]. */
9079 void
9082 {
9090 {
9097 }
9098 }
9100 /* Try to view-convert VECTOR_CST EXPR to VECTOR_TYPE TYPE by operating
9101 directly on the VECTOR_CST encoding, in a way that works for variable-
9102 length vectors. Return the resulting VECTOR_CST on success or null
9103 on failure. */
9105 static tree
9107 {
9119 /* We can only preserve the semantics of a stepped pattern if the new
9120 vector element is an integer of the same size. */
9125 /* The number of bits needed to encode one element from every pattern
9126 of the original vector. */
9127 unsigned int expr_sequence_bits
9130 /* The number of bits needed to encode one element from every pattern
9131 of the result. */
9132 unsigned int type_sequence_bits
9135 /* Don't try to read more bytes than are available, which can happen
9136 for constant-sized vectors if TYPE has larger elements than EXPR_TYPE.
9137 The general VIEW_CONVERT handling can cope with that case, so there's
9138 no point complicating things here. */
9141 BITS_PER_UNIT);
9146 /* Get enough bytes of EXPR to form the new encoding. */
9154 /* Reencode the bytes as TYPE. */
9158 }
9160 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
9161 TYPE at compile-time. If we're unable to perform the conversion
9162 return NULL_TREE. */
9164 static tree
9166 {
9167 /* We support up to 512-bit values (for V8DFmode). */
9171 /* Check that the host and target are sane. */
9184 }
9186 /* Build an expression for the address of T. Folds away INDIRECT_REF
9187 to avoid confusing the gimplify process. */
9189 tree
9191 {
9192 /* The size of the object is not relevant when talking about its address. */
9197 {
9202 }
9205 {
9210 }
9217 {
9222 }
9223 else
9227 }
9229 /* Build an expression for the address of T. */
9231 tree
9233 {
9237 }
9239 /* Fold a unary expression of code CODE and type TYPE with operand
9240 OP0. Return the folded expression if folding is successful.
9241 Otherwise, return NULL_TREE. */
9243 tree
9245 {
9246 tree tem;
9247 tree arg0;
9255 {
9258 {
9259 /* Don't use STRIP_NOPS, because signedness of argument type
9260 matters. */
9262 }
9263 else
9264 {
9265 /* Strip any conversions that don't change the mode. This
9266 is safe for every expression, except for a comparison
9267 expression because its signedness is derived from its
9268 operands.
9270 Note that this is done as an internal manipulation within
9271 the constant folder, in order to find the simplest
9272 representation of the arguments so that their form can be
9273 studied. In any cases, the appropriate type conversions
9274 should be put back in the tree that will get out of the
9275 constant folder. */
9277 }
9280 {
9283 {
9287 }
9288 }
9289 }
9296 {
9303 {
9317 /* If this was a conversion, and all we did was to move into
9318 inside the COND_EXPR, bring it back out. But leave it if
9319 it is a conversion from integer to integer and the
9320 result precision is no wider than a word since such a
9321 conversion is cheap and may be optimized away by combine,
9322 while it couldn't if it were outside the COND_EXPR. Then return
9323 so we don't get into an infinite recursion loop taking the
9324 conversion out and then back in. */
9336 && (INTEGRAL_TYPE_P
9349 }
9350 }
9353 {
9359 CASE_CONVERT:
9363 {
9364 /* If we have (type) (a CMP b) and type is an integral type, return
9365 new expression involving the new type. Canonicalize
9366 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
9367 non-integral type.
9368 Do not fold the result as that would not simplify further, also
9369 folding again results in recursions. */
9379 }
9381 /* Handle (T *)&A.B.C for A being of type T and B and C
9382 living at offset zero. This occurs frequently in
9383 C++ upcasting and then accessing the base. */
9387 {
9389 tree offset;
9390 machine_mode mode;
9392 tree base
9396 /* If the reference was to a (constant) zero offset, we can use
9397 the address of the base if it has the same base type
9398 as the result type and the pointer type is unqualified. */
9406 }
9410 /* Detect assigning a bitfield. */
9412 && DECL_BIT_FIELD
9414 {
9415 /* Don't leave an assignment inside a conversion
9416 unless assigning a bitfield. */
9418 /* First do the assignment, then return converted constant. */
9423 }
9425 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
9426 constants (if x has signed type, the sign bit cannot be set
9427 in c). This folds extension into the BIT_AND_EXPR.
9428 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
9429 very likely don't have maximal range for their precision and this
9430 transformation effectively doesn't preserve non-maximal ranges. */
9434 {
9445 <= HOST_BITS_PER_WIDE_INT
9447 {
9451 cst &= HOST_WIDE_INT_M1U
9455 && !flag_syntax_only
9458 {
9462 }
9463 }
9465 {
9470 }
9471 }
9473 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
9474 cast (T1)X will fold away. We assume that this happens when X itself
9475 is a cast. */
9479 {
9483 /* If -fsanitize=alignment, avoid this optimization in GENERIC
9484 when the pointed type needs higher alignment than
9485 the p+ first operand's pointed type. */
9494 }
9496 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
9497 of the same precision, and X is an integer type not narrower than
9498 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
9504 {
9510 }
9512 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
9513 type of X and Y (integer types only). */
9518 {
9519 /* Be careful not to introduce new overflows. */
9520 tree mult_type;
9523 else
9527 {
9534 }
9535 }
9541 {
9548 }
9559 /* Convert fabs((double)float) into (double)fabsf(float). */
9562 {
9568 targ0));
9569 }
9573 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
9592 /* Note that the operand of this must be an int
9593 and its values must be 0 or 1.
9594 ("true" is a fixed value perhaps depending on the language,
9595 but we don't handle values other than 1 correctly yet.) */
9602 /* Fold *&X to X if X is an lvalue. */
9604 {
9611 }
9617 }
9620 /* If the operation was a conversion do _not_ mark a resulting constant
9621 with TREE_OVERFLOW if the original constant was not. These conversions
9622 have implementation defined behavior and retaining the TREE_OVERFLOW
9623 flag here would confuse later passes such as VRP. */
9624 tree
9627 {
9636 }
9638 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
9639 operands OP0 and OP1. LOC is the location of the resulting expression.
9640 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
9641 Return the folded expression if folding is successful. Otherwise,
9642 return NULL_TREE. */
9643 static tree
9646 {
9647 tree tem;
9649 /* We only do these simplifications if we are optimizing. */
9653 /* Check for things like (A || B) && (A || C). We can convert this
9654 to A || (B && C). Note that either operator can be any of the four
9655 truth and/or operations and the transformation will still be
9656 valid. Also note that we only care about order for the
9657 ANDIF and ORIF operators. If B contains side effects, this
9658 might change the truth-value of A. */
9665 {
9685 /* This case if tricky because we must either have commutative
9686 operators or else A10 must not have side-effects. */
9692 a01);
9693 }
9695 /* See if we can build a range comparison. */
9701 {
9705 }
9709 {
9713 }
9715 /* Check for the possibility of merging component references. If our
9716 lhs is another similar operation, try to merge its rhs with our
9717 rhs. Then try to merge our lhs and rhs. */
9728 logical_op_non_short_circuit
9736 {
9743 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
9744 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
9745 We don't want to pack more than two leafs to a non-IF AND/OR
9746 expression.
9747 If tree-code of left-hand operand isn't an AND/OR-IF code and not
9748 equal to IF-CODE, then we don't want to add right-hand operand.
9749 If the inner right-hand side of left-hand operand has
9750 side-effects, or isn't simple, then we can't add to it,
9751 as otherwise we might destroy if-sequence. */
9754 /* Needed for sequence points to handle trappings, and
9755 side-effects. */
9757 {
9759 arg1);
9761 tem);
9762 }
9763 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
9764 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
9767 /* Needed for sequence points to handle trappings, and
9768 side-effects. */
9770 {
9775 }
9776 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
9777 into (A OR B).
9778 For sequence point consistancy, we need to check for trapping,
9779 and side-effects. */
9783 }
9786 }
9788 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9789 by changing CODE to reduce the magnitude of constants involved in
9790 ARG0 of the comparison.
9791 Returns a canonicalized comparison tree if a simplification was
9792 possible, otherwise returns NULL_TREE.
9793 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9794 valid if signed overflow is undefined. */
9796 static tree
9800 {
9805 /* Match A +- CST code arg1. We can change this only if overflow
9806 is undefined. */
9809 /* In principle pointers also have undefined overflow behavior,
9810 but that causes problems elsewhere. */
9817 /* Identify the constant in arg0 and its sign. */
9821 /* Overflowed constants and zero will cause problems. */
9826 /* See if we can reduce the magnitude of the constant in
9827 arg0 by changing the comparison code. */
9828 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9832 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9836 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9840 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9844 else
9848 /* Now build the constant reduced in magnitude. But not if that
9849 would produce one outside of its types range. */
9865 }
9867 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9868 overflow further. Try to decrease the magnitude of constants involved
9869 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9870 and put sole constants at the second argument position.
9871 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9873 static tree
9876 {
9877 tree t;
9882 /* Try canonicalization by simplifying arg0. */
9887 {
9891 }
9893 /* Try canonicalization by simplifying arg1 using the swapped
9894 comparison. */
9902 }
9904 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9905 space. This is used to avoid issuing overflow warnings for
9906 expressions like &p->x which cannot wrap. */
9908 static bool
9910 {
9917 poly_wide_int wi_offset;
9923 else
9928 precision);
9943 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9944 array. */
9953 }
9955 /* Return a positive integer when the symbol DECL is known to have
9956 a nonzero address, zero when it's known not to (e.g., it's a weak
9957 symbol), and a negative integer when the symbol is not yet in the
9958 symbol table and so whether or not its address is zero is unknown.
9959 For function local objects always return positive integer. */
9960 static int
9962 {
9963 /* Normally, don't do anything for variables and functions before symtab is
9964 built; it is quite possible that DECL will be declared weak later.
9965 But if folding_initializer, we need a constant answer now, so create
9966 the symtab entry and prevent later weak declaration. */
9969 = (folding_initializer
9974 /* Function local objects are never NULL. */
9982 }
9984 /* Subroutine of fold_binary. This routine performs all of the
9985 transformations that are common to the equality/inequality
9986 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9987 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9988 fold_binary should call fold_binary. Fold a comparison with
9989 tree code CODE and type TYPE with operands OP0 and OP1. Return
9990 the folded comparison or NULL_TREE. */
9992 static tree
9995 {
10005 /* For comparisons of pointers we can decompose it to a compile time
10006 comparison of the base objects and the offsets into the object.
10007 This requires at least one operand being an ADDR_EXPR or a
10008 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
10014 {
10017 machine_mode mode;
10021 /* Get base and offset for the access. Strip ADDR_EXPR for
10022 get_inner_reference, but put it back by stripping INDIRECT_REF
10023 off the base object if possible. indirect_baseN will be true
10024 if baseN is not an address but refers to the object itself. */
10027 {
10028 base0
10034 else
10036 }
10038 {
10042 {
10043 base0
10049 else
10051 }
10054 else
10058 {
10065 }
10066 }
10070 {
10071 base1
10077 else
10079 }
10081 {
10085 {
10086 base1
10092 else
10094 }
10097 else
10101 {
10108 }
10109 }
10111 /* If we have equivalent bases we might be able to simplify. */
10115 {
10116 /* We can fold this expression to a constant if the non-constant
10117 offset parts are equal. */
10121 && (equality_code
10122 || (indirect_base0
10125 {
10131 "occur when comparing P +- C1 with "
10133 WARN_STRICT_OVERFLOW_CONDITIONAL);
10136 {
10174 }
10175 }
10176 /* We can simplify the comparison to a comparison of the variable
10177 offset parts if the constant offset parts are equal.
10178 Be careful to use signed sizetype here because otherwise we
10179 mess with array offsets in the wrong way. This is possible
10180 because pointer arithmetic is restricted to retain within an
10181 object and overflow on pointer differences is undefined as of
10182 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
10184 && (equality_code
10185 || (indirect_base0
10188 {
10189 /* By converting to signed sizetype we cover middle-end pointer
10190 arithmetic which operates on unsigned pointer types of size
10191 type size and ARRAY_REF offsets which are properly sign or
10192 zero extended from their type in case it is narrower than
10193 sizetype. */
10196 else
10200 else
10207 "occur when comparing P +- C1 with "
10209 WARN_STRICT_OVERFLOW_COMPARISON);
10212 }
10213 }
10214 /* For equal offsets we can simplify to a comparison of the
10215 base addresses. */
10217 && (indirect_base0
10219 && (indirect_base1
10224 {
10230 }
10231 /* Comparison between an ordinary (non-weak) symbol and a null
10232 pointer can be eliminated since such symbols must have a non
10233 null address. In C, relational expressions between pointers
10234 to objects and null pointers are undefined. The results
10235 below follow the C++ rules with the additional property that
10236 every object pointer compares greater than a null pointer.
10237 */
10240 /* Avoid folding references to struct members at offset 0 to
10241 prevent tests like '&ptr->firstmember == 0' from getting
10242 eliminated. When ptr is null, although the -> expression
10243 is strictly speaking invalid, GCC retains it as a matter
10244 of QoI. See PR c/44555. */
10247 && indirect_base0
10248 /* The caller guarantees that when one of the arguments is
10249 constant (i.e., null in this case) it is second. */
10251 {
10253 {
10264 }
10265 }
10266 }
10268 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
10269 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
10270 the resulting offset is smaller in absolute value than the
10271 original one and has the same sign. */
10280 {
10285 tree cst;
10287 "occur when combining constants around "
10290 /* Put the constant on the side where it doesn't overflow and is
10291 of lower absolute value and of same sign than before. */
10298 {
10301 variable1,
10305 }
10313 {
10319 variable2);
10320 }
10321 }
10327 /* If we are comparing an expression that just has comparisons
10328 of two integer values, arithmetic expressions of those comparisons,
10329 and constants, we can simplify it. There are only three cases
10330 to check: the two values can either be equal, the first can be
10331 greater, or the second can be greater. Fold the expression for
10332 those three values. Since each value must be 0 or 1, we have
10333 eight possibilities, each of which corresponds to the constant 0
10334 or 1 or one of the six possible comparisons.
10336 This handles common cases like (a > b) == 0 but also handles
10337 expressions like ((x > y) - (y > x)) > 0, which supposedly
10338 occur in macroized code. */
10341 {
10345 /* Don't handle degenerate cases here; they should already
10346 have been handled anyway. */
10355 {
10359 /* We can't just pass T to eval_subst in case cval1 or cval2
10360 was the same as ARG1. */
10362 tree high_result
10366 arg1);
10367 tree equal_result
10371 arg1);
10372 tree low_result
10376 arg1);
10378 /* All three of these results should be 0 or 1. Confirm they are.
10379 Then use those values to select the proper code to use. */
10384 {
10385 /* Make a 3-bit mask with the high-order bit being the
10386 value for `>', the next for '=', and the low for '<'. */
10390 {
10392 /* Always false. */
10413 /* Always true. */
10415 }
10418 }
10419 }
10420 }
10423 }
10426 /* Subroutine of fold_binary. Optimize complex multiplications of the
10427 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
10428 argument EXPR represents the expression "z" of type TYPE. */
10430 static tree
10432 {
10437 {
10440 }
10442 {
10445 }
10446 else
10447 {
10451 }
10460 }
10463 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
10464 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
10465 true if successful. */
10467 static bool
10469 {
10474 {
10477 }
10479 {
10485 else
10487 }
10488 else
10494 }
10496 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
10497 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
10498 NULL_TREE otherwise. */
10500 tree
10502 {
10523 {
10524 HOST_WIDE_INT index;
10530 }
10533 {
10539 }
10540 else
10542 }
10544 /* Try to fold a pointer difference of type TYPE two address expressions of
10545 array references AREF0 and AREF1 using location LOC. Return a
10546 simplified expression for the difference or NULL_TREE. */
10548 static tree
10552 {
10557 /* If the bases are array references as well, recurse. If the bases
10558 are pointer indirections compute the difference of the pointers.
10559 If the bases are equal, we are set. */
10562 && (base_offset
10564 use_pointer_diff)))
10567 && (base_offset
10568 = use_pointer_diff
10578 {
10584 base_offset,
10587 }
10589 }
10591 /* If the real or vector real constant CST of type TYPE has an exact
10592 inverse, return it, else return NULL. */
10594 tree
10596 {
10597 REAL_VALUE_TYPE r;
10598 tree unit_type;
10599 machine_mode mode;
10602 {
10612 {
10616 tree_vector_builder elts;
10621 {
10626 }
10629 }
10633 }
10634 }
10636 /* Mask out the tz least significant bits of X of type TYPE where
10637 tz is the number of trailing zeroes in Y. */
10638 static wide_int
10640 {
10645 }
10647 /* Return true when T is an address and is known to be nonzero.
10648 For floating point we further ensure that T is not denormal.
10649 Similar logic is present in nonzero_address in rtlanal.h.
10651 If the return value is based on the assumption that signed overflow
10652 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
10653 change *STRICT_OVERFLOW_P. */
10655 static bool
10657 {
10661 /* Doing something useful for floating point would need more work. */
10667 {
10670 strict_overflow_p);
10676 strict_overflow_p);
10684 }
10687 {
10690 strict_overflow_p);
10698 strict_overflow_p);
10713 strict_overflow_p);
10717 strict_overflow_p);
10720 {
10732 }
10736 }
10738 }
10740 /* Return true when T is an address and is known to be nonzero.
10741 Handle warnings about undefined signed overflow. */
10743 bool
10745 {
10752 "determining that expression is always "
10754 WARN_STRICT_OVERFLOW_MISC);
10756 }
10758 /* Return true if T is known not to be equal to an integer W. */
10760 bool
10762 {
10763 int_range_max vr;
10765 {
10775 else
10781 /* If T has some known zero bits and W has any of those bits set,
10782 then T is known not to be equal to W. */
10790 }
10791 }
10793 /* Fold a binary expression of code CODE and type TYPE with operands
10794 OP0 and OP1. LOC is the location of the resulting expression.
10795 Return the folded expression if folding is successful. Otherwise,
10796 return NULL_TREE. */
10798 tree
10801 {
10816 /* Strip any conversions that don't change the mode. This is
10817 safe for every expression, except for a comparison expression
10818 because its signedness is derived from its operands. So, in
10819 the latter case, only strip conversions that don't change the
10820 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10821 preserved.
10823 Note that this is done as an internal manipulation within the
10824 constant folder, in order to find the simplest representation
10825 of the arguments so that their form can be studied. In any
10826 cases, the appropriate type conversions should be put back in
10827 the tree that will get out of the constant folder. */
10830 {
10833 }
10834 else
10835 {
10838 }
10840 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10841 constant but we can't do arithmetic on them. */
10843 {
10846 {
10850 }
10851 }
10853 /* If this is a commutative operation, and ARG0 is a constant, move it
10854 to ARG1 to reduce the number of tests below. */
10859 /* Likewise if this is a comparison, and ARG0 is a constant, move it
10860 to ARG1 to reduce the number of tests below. */
10869 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10871 First check for cases where an arithmetic operation is applied to a
10872 compound, conditional, or comparison operation. Push the arithmetic
10873 operation inside the compound or conditional to see if any folding
10874 can then be done. Convert comparison to conditional for this purpose.
10875 The also optimizes non-constant cases that used to be done in
10876 expand_expr.
10878 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10879 one of the operands is a comparison and the other is a comparison, a
10880 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10881 code below would make the expression more complex. Change it to a
10882 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10883 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10896 {
10900 boolean_type_node,
10908 }
10912 {
10914 {
10919 tem);
10920 }
10922 {
10927 tem);
10928 }
10933 {
10939 }
10944 {
10950 }
10951 }
10954 {
10956 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10959 {
10965 }
10967 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10970 {
10971 tree base;
10972 poly_int64 coffset;
10981 }
10986 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10992 arg1),
10994 arg0)));
11000 {
11001 /* X + (X / CST) * -CST is X % CST. */
11006 {
11015 cst0));
11016 }
11017 }
11019 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
11020 one. Make sure the type is not saturating and has the signedness of
11021 the stripped operands, as fold_plusminus_mult_expr will re-associate.
11022 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
11029 {
11033 }
11036 {
11037 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
11038 (plus (plus (mult) (mult)) (foo)) so that we can
11039 take advantage of the factoring cases below. */
11048 {
11054 else
11067 parg0),
11069 marg)),
11073 return
11079 parg1)));
11080 }
11081 }
11082 else
11083 {
11084 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
11085 to __complex__ ( x, y ). This is not the same for SNaNs or
11086 if signed zeros are involved. */
11090 {
11097 {
11101 {
11107 }
11109 {
11115 }
11116 }
11117 }
11119 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
11120 We associate floats only if the user has specified
11121 -fassociative-math. */
11125 {
11130 {
11131 tree tree0;
11134 }
11135 }
11136 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
11137 We associate floats only if the user has specified
11138 -fassociative-math. */
11142 {
11147 {
11148 tree tree0;
11151 }
11152 }
11153 }
11155 bit_rotate:
11156 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
11157 is a rotate of A by C1 bits. */
11158 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
11159 is a rotate of A by B bits.
11160 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
11161 though in this case CODE must be | and not + or ^, otherwise
11162 it doesn't return A when B is 0. */
11163 {
11165 tree rtype;
11174 /* Only create rotates in complete modes. Other cases are not
11175 expanded properly. */
11178 {
11191 {
11196 }
11201 {
11204 code0 == LSHIFT_EXPR
11207 }
11209 {
11219 {
11223 orig_tree01);
11225 }
11226 }
11230 {
11241 {
11245 orig_tree01);
11247 }
11248 }
11249 }
11250 }
11252 associate:
11253 /* In most languages, can't associate operations on floats through
11254 parentheses. Rather than remember where the parentheses were, we
11255 don't associate floats at all, unless the user has specified
11256 -fassociative-math.
11257 And, we need to make sure type is not saturating. */
11261 {
11267 /* Split both trees into variables, constants, and literals. Then
11268 associate each group together, the constants with literals,
11269 then the result with variables. This increases the chances of
11270 literals being recombined later and of generating relocatable
11271 expressions for the sum of a constant and literal. */
11279 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
11283 /* With undefined overflow prefer doing association in a type
11284 which wraps on overflow, if that is one of the operand types. */
11287 {
11295 }
11297 /* With undefined overflow we can only associate constants with one
11298 variable, and constants whose association doesn't overflow. */
11301 {
11303 {
11304 /* ??? If split_tree would handle NEGATE_EXPR we could
11305 simply reject these cases and the allowed cases would
11306 be the var0/minus_var1 ones. */
11312 {
11315 }
11322 {
11325 }
11331 /* The only case we can still associate with two variables
11332 is if they cancel out. */
11336 }
11342 }
11344 /* Only do something if we found more than two objects. Otherwise,
11345 nothing has changed and we risk infinite recursion. */
11353 {
11365 {
11369 }
11371 {
11375 }
11377 /* Preserve the MINUS_EXPR if the negative part of the literal is
11378 greater than the positive part. Otherwise, the multiplicative
11379 folding code (i.e extract_muldiv) may be fooled in case
11380 unsigned constants are subtracted, like in the following
11381 example: ((X*2 + 4) - 8U)/2. */
11383 {
11387 /* But avoid ending up with only negated parts. */
11389 {
11393 }
11394 else
11395 {
11399 }
11400 }
11402 /* Don't introduce overflows through reassociation. */
11407 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
11414 /* Eliminate minus_con0. */
11416 {
11423 else
11426 }
11428 /* Eliminate minus_var0. */
11430 {
11434 else
11437 }
11439 return
11442 }
11443 }
11449 /* Fold &a[i] - &a[j] to i-j. */
11454 {
11458 code
11462 }
11464 /* Further transformations are not for pointers. */
11468 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
11471 /* If arg0 is e.g. unsigned int and type is int, then this could
11472 introduce UB, because if A is INT_MIN at runtime, the original
11473 expression can be well defined while the latter is not.
11474 See PR83269. */
11483 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
11484 __complex__ ( x, -y ). This is not the same for SNaNs or if
11485 signed zeros are involved. */
11489 {
11496 {
11500 {
11502 arg1r ? arg1r
11507 }
11509 {
11513 arg1i ? arg1i
11516 }
11517 }
11518 }
11520 /* A - B -> A + (-B) if B is easily negatable. */
11524 /* Avoid this transformation if B is a positive REAL_CST. */
11532 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
11533 one. Make sure the type is not saturating and has the signedness of
11534 the stripped operands, as fold_plusminus_mult_expr will re-associate.
11535 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
11542 {
11546 }
11552 {
11553 /* Transform x * -C into -x * C if x is easily negatable. */
11568 {
11571 "occur when simplifying "
11573 WARN_STRICT_OVERFLOW_MISC);
11575 }
11577 /* Optimize z * conj(z) for integer complex numbers. */
11584 }
11585 else
11586 {
11587 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11588 This is not the same for NaNs or if signed zeros are
11589 involved. */
11595 {
11598 return
11604 return
11609 }
11611 /* Optimize z * conj(z) for floating point complex numbers.
11612 Guarded by flag_unsafe_math_optimizations as non-finite
11613 imaginary components don't produce scalar results. */
11622 }
11626 /* Canonicalize (X & C1) | C2. */
11630 {
11635 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11643 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11645 {
11648 }
11650 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11651 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11652 mode which allows further optimizations. */
11657 {
11662 {
11665 }
11666 }
11669 {
11674 }
11675 }
11677 /* See if this can be simplified into a rotate first. If that
11678 is unsuccessful continue in the association code. */
11682 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11690 /* See if this can be simplified into a rotate first. If that
11691 is unsuccessful continue in the association code. */
11695 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11700 {
11701 tree tem2;
11708 }
11709 /* Fold ~X & 1 as (X & 1) == 0. */
11713 {
11714 tree tem2;
11721 }
11722 /* Fold !X & 1 as X == 0. */
11725 {
11729 }
11731 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11732 multiple of 1 << CST. */
11734 {
11741 }
11743 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11744 bits from CST2. */
11748 {
11750 wide_int masked
11757 {
11758 /* Avoid the transform if arg1 is a mask of some
11759 mode which allows further optimizations. */
11766 }
11767 }
11769 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11772 {
11777 return
11779 }
11784 /* Don't touch a floating-point divide by zero unless the mode
11785 of the constant can represent infinity. */
11791 /* (-A) / (-B) -> A / B */
11803 /* Fall through */
11806 /* Simplify A / (B << N) where A and B are positive and B is
11807 a power of 2, to A >> (N + log2(B)). */
11812 {
11815 {
11823 WARN_STRICT_OVERFLOW_MISC);
11829 }
11830 }
11832 /* Fall through */
11840 /* Convert -A / -B to A / B when the type is signed and overflow is
11841 undefined. */
11845 {
11848 "when distributing negation across "
11850 WARN_STRICT_OVERFLOW_MISC);
11855 }
11859 {
11862 "when distributing negation across "
11864 WARN_STRICT_OVERFLOW_MISC);
11869 }
11871 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11872 operation, EXACT_DIV_EXPR.
11874 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11875 At one time others generated faster code, it's not clear if they do
11876 after the last round to changes to the DIV code in expmed.cc. */
11887 {
11891 WARN_STRICT_OVERFLOW_MISC);
11893 }
11905 {
11909 WARN_STRICT_OVERFLOW_MISC);
11911 }
11919 /* Since negative shift count is not well-defined,
11920 don't try to compute it in the compiler. */
11926 /* If we have a rotate of a bit operation with the rotate count and
11927 the second operand of the bit operation both constant,
11928 permute the two operations. */
11934 {
11942 }
11944 /* Two consecutive rotates adding up to the some integer
11945 multiple of the precision of the type can be ignored. */
11961 /* Note that the operands of this must be ints
11962 and their values must be 0 or 1.
11963 ("true" is a fixed value perhaps depending on the language.) */
11964 /* If first arg is constant zero, return it. */
11967 /* FALLTHRU */
11969 /* If either arg is constant true, drop it. */
11973 /* Preserve sequence points. */
11976 /* If second arg is constant zero, result is zero, but first arg
11977 must be evaluated. */
11980 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11981 case will be handled here. */
11985 /* !X && X is always false. */
11989 /* X && !X is always false. */
11994 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
11995 means A >= Y && A != MAX, but in this case we know that
11996 A < X <= MAX. */
12000 {
12008 }
12017 /* Note that the operands of this must be ints
12018 and their values must be 0 or true.
12019 ("true" is a fixed value perhaps depending on the language.) */
12020 /* If first arg is constant true, return it. */
12023 /* FALLTHRU */
12025 /* If either arg is constant zero, drop it. */
12029 /* Preserve sequence points. */
12032 /* If second arg is constant true, result is true, but we must
12033 evaluate first arg. */
12036 /* Likewise for first arg, but note this only occurs here for
12037 TRUTH_OR_EXPR. */
12041 /* !X || X is always true. */
12045 /* X || !X is always true. */
12050 /* (X && !Y) || (!X && Y) is X ^ Y */
12053 {
12070 }
12079 /* If the second arg is constant zero, drop it. */
12082 /* If the second arg is constant true, this is a logical inversion. */
12084 {
12087 }
12088 /* Identical arguments cancel to zero. */
12092 /* !X ^ X is always true. */
12097 /* X ^ !X is always true. */
12113 /* bool_var != 1 becomes !bool_var. */
12120 /* bool_var == 0 becomes !bool_var. */
12127 /* !exp != 0 becomes !exp */
12132 /* If this is an EQ or NE comparison with zero and ARG0 is
12133 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12134 two operations, but the latter can be done in one less insn
12135 on machines that have only two-operand insns or on which a
12136 constant cannot be the first operand. */
12139 {
12144 {
12152 }
12155 {
12163 }
12164 }
12166 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12167 C1 is a valid shift constant, and C2 is a power of two, i.e.
12168 a single bit. */
12172 {
12177 {
12182 /* Check for a valid shift count. */
12184 {
12188 /* If (C2 << C1) doesn't overflow, then
12189 ((X >> C1) & C2) != 0 can be rewritten as
12190 (X & (C2 << C1)) != 0. */
12192 {
12199 }
12200 /* Otherwise, for signed (arithmetic) shifts,
12201 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12202 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12208 /* Otherwise, of unsigned (logical) shifts,
12209 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12210 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12211 else
12215 arg000);
12216 }
12217 }
12218 }
12220 /* If this is a comparison of a field, we may be able to simplify it. */
12223 /* Handle the constant case even without -O
12224 to make sure the warnings are given. */
12226 {
12230 }
12232 /* Optimize comparisons of strlen vs zero to a compare of the
12233 first character of the string vs zero. To wit,
12234 strlen(ptr) == 0 => *ptr == 0
12235 strlen(ptr) != 0 => *ptr != 0
12236 Other cases should reduce to one of these two (or a constant)
12237 due to the return value of strlen being unsigned. */
12239 {
12247 {
12248 tree ptrtype
12250 TYPE_QUAL_CONST));
12256 }
12257 }
12259 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12260 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12264 {
12269 {
12271 {
12274 }
12277 }
12278 }
12280 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12281 (X & C) == 0 when C is a single bit. */
12286 {
12293 arg1));
12294 }
12296 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12297 constant C is a power of two, i.e. a single bit. */
12304 {
12308 }
12310 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12311 when is C is a power of two, i.e. a single bit. */
12318 {
12324 }
12328 {
12331 }
12335 {
12342 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12343 operand_equal_p guarantees no side-effects so we don't need
12344 to use omit_one_operand on Z. */
12348 arg10));
12352 arg11));
12356 arg10));
12360 arg11));
12362 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12365 {
12371 }
12372 }
12374 /* Attempt to simplify equality/inequality comparisons of complex
12375 values. Only lower the comparison if the result is known or
12376 can be simplified to a single scalar comparison. */
12381 {
12386 {
12389 }
12390 else
12391 {
12394 }
12397 {
12400 }
12401 else
12402 {
12405 }
12409 {
12411 {
12416 }
12417 else
12418 {
12423 }
12424 }
12428 {
12430 {
12435 }
12436 else
12437 {
12442 }
12443 }
12444 }
12456 /* Transform comparisons of the form X +- C CMP X. */
12461 {
12466 /* (X - c) > X becomes false. */
12472 /* Likewise (X + c) < X becomes false. */
12478 /* Convert (X - c) <= X to true. */
12485 /* Convert (X + c) >= X to true. */
12491 }
12493 /* If we are comparing an ABS_EXPR with a constant, we can
12494 convert all the cases into explicit comparisons, but they may
12495 well not be faster than doing the ABS and one comparison.
12496 But ABS (X) <= C is a range comparison, which becomes a subtraction
12497 and a comparison, and is probably faster. */
12511 /* Convert ABS_EXPR<x> >= 0 to true. */
12518 {
12521 "when simplifying comparison of "
12523 WARN_STRICT_OVERFLOW_CONDITIONAL);
12526 arg0);
12527 }
12529 /* Convert ABS_EXPR<x> < 0 to false. */
12534 {
12537 "when simplifying comparison of "
12539 WARN_STRICT_OVERFLOW_CONDITIONAL);
12542 arg0);
12543 }
12545 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12546 and similarly for >= into !=. */
12556 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
12557 otherwise Y might be >= # of bits in X's type and thus e.g.
12558 (unsigned char) (1 << Y) for Y 15 might be 0.
12559 If the cast is widening, then 1 << Y should have unsigned type,
12560 otherwise if Y is number of bits in the signed shift type minus 1,
12561 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
12562 31 might be 0xffffffff80000000. */
12575 {
12581 }
12593 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12594 {
12606 }
12611 /* When pedantic, a compound expression can be neither an lvalue
12612 nor an integer constant expression. */
12615 /* Don't let (0, 0) be null pointer constant. */
12621 /* An ASSERT_EXPR should never be passed to fold_binary. */
12627 }
12629 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
12630 ((A & N) + B) & M -> (A + B) & M
12631 Similarly if (N & M) == 0,
12632 ((A | N) + B) & M -> (A + B) & M
12633 and for - instead of + (or unary - instead of +)
12634 and/or ^ instead of |.
12635 If B is constant and (B & M) == 0, fold into A & M.
12637 This function is a helper for match.pd patterns. Return non-NULL
12638 type in which the simplified operation should be performed only
12639 if any optimization is possible.
12641 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
12642 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
12643 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
12644 +/-. */
12645 tree
12650 {
12665 wide_int cst0;
12667 /* Now we know that arg0 is (C + D) or (C - D) or -C and
12668 arg1 (M) is == (1LL << cst) - 1.
12669 Store C into PMOP[0] and D into PMOP[1]. */
12676 {
12683 {
12686 }
12689 /* If C or D is of the form (A & N) where
12690 (N & M) == M, or of the form (A | N) or
12691 (A ^ N) where (N & M) == 0, replace it with A. */
12697 /* If C or D is a N where (N & M) == 0, it can be
12698 omitted (replaced with 0). */
12703 /* Similarly, with C - N where (-N & M) == 0. */
12711 }
12713 /* Only build anything new if we optimized one or both arguments above. */
12719 else
12721 }
12723 /* Used by contains_label_[p1]. */
12725 struct contains_label_data
12726 {
12729 };
12731 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
12732 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
12733 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
12735 static tree
12737 {
12740 {
12751 {
12759 }
12768 }
12769 }
12771 /* Return whether the sub-tree ST contains a label which is accessible from
12772 outside the sub-tree. */
12774 static bool
12776 {
12780 }
12782 /* Fold a ternary expression of code CODE and type TYPE with operands
12783 OP0, OP1, and OP2. Return the folded expression if folding is
12784 successful. Otherwise, return NULL_TREE. */
12786 tree
12789 {
12790 tree tem;
12797 /* If this is a commutative operation, and OP0 is a constant, move it
12798 to OP1 to reduce the number of tests below. */
12807 /* Strip any conversions that don't change the mode. This is safe
12808 for every expression, except for a comparison expression because
12809 its signedness is derived from its operands. So, in the latter
12810 case, only strip conversions that don't change the signedness.
12812 Note that this is done as an internal manipulation within the
12813 constant folder, in order to find the simplest representation of
12814 the arguments so that their form can be studied. In any cases,
12815 the appropriate type conversions should be put back in the tree
12816 that will get out of the constant folder. */
12818 {
12821 }
12824 {
12827 }
12830 {
12833 }
12836 {
12840 {
12846 }
12851 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12852 so all simple results must be passed through pedantic_non_lvalue. */
12854 {
12857 /* Only optimize constant conditions when the selected branch
12858 has the same type as the COND_EXPR. This avoids optimizing
12859 away "c ? x : throw", where the throw has a void type.
12860 Avoid throwing away that operand which contains label. */
12867 }
12869 {
12876 {
12879 {
12887 }
12892 }
12893 }
12895 /* If we have A op B ? A : C, we may be able to convert this to a
12896 simpler expression, depending on the operation and the values
12897 of B and C. Signed zeros prevent all of these transformations,
12898 for reasons given above each one.
12900 Also try swapping the arguments and inverting the conditional. */
12904 {
12911 }
12916 {
12923 arg00,
12924 arg01,
12928 }
12930 /* If the second operand is simpler than the third, swap them
12931 since that produces better jump optimization results. */
12934 {
12936 /* See if this can be inverted. If it can't, possibly because
12937 it was a floating-point inequality comparison, don't do
12938 anything. */
12942 }
12944 /* Convert A ? 1 : 0 to simply A. */
12949 /* If we try to convert OP0 to our type, the
12950 call to fold will try to move the conversion inside
12951 a COND, which will recurse. In that case, the COND_EXPR
12952 is probably the best choice, so leave it alone. */
12956 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12957 over COND_EXPR in cases such as floating point comparisons. */
12966 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12971 {
12972 /* sign_bit_p looks through both zero and sign extensions,
12973 but for this optimization only sign extensions are
12974 usable. */
12977 {
12980 {
12983 }
12985 }
12986 /* sign_bit_p only checks ARG1 bits within A's precision.
12987 If <sign bit of A> has wider type than A, bits outside
12988 of A's precision in <sign bit of A> need to be checked.
12989 If they are all 0, this optimization needs to be done
12990 in unsigned A's type, if they are all 1 in signed A's type,
12991 otherwise this can't be done. */
12997 {
12999 tree tem_type;
13012 {
13015 }
13017 {
13020 }
13021 else
13023 }
13026 return
13032 arg1)));
13033 }
13035 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13036 already handled above. */
13041 {
13051 op1);
13052 }
13054 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13055 is probably obsolete because the first operand should be a
13056 truth value (that's why we have the two cases above), but let's
13057 leave it in until we can confirm this for all front-ends. */
13065 /* operand_equal_p compares just value, not precision, so e.g.
13066 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
13067 second operand 32-bit -128, which is not a power of two (or vice
13068 versa. */
13072 /* Disable the transformations below for vectors, since
13073 fold_binary_op_with_conditional_arg may undo them immediately,
13074 yielding an infinite loop. */
13078 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13087 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13092 {
13094 /* Only perform transformation if ARG0 is easily inverted. */
13098 ? BIT_IOR_EXPR
13101 op1);
13102 }
13104 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13109 {
13111 /* Only perform transformation if ARG0 is easily inverted. */
13117 op2);
13118 }
13120 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13132 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13133 of fold_ternary on them. */
13143 {
13145 unsigned HOST_WIDE_INT width
13156 {
13161 {
13163 {
13168 }
13174 }
13175 }
13176 }
13178 /* On constants we can use native encode/interpret to constant
13179 fold (nearly) all BIT_FIELD_REFs. */
13185 {
13188 /* Limit us to a reasonable amount of work. To relax the
13189 other limitations we need bit-shifting of the buffer
13190 and rounding up the size. */
13194 {
13196 unsigned HOST_WIDE_INT len
13201 {
13206 }
13207 }
13208 }
13213 /* Perform constant folding of BIT_INSERT_EXPR. */
13217 {
13218 /* Build a vector of integers from the tree mask. */
13219 vec_perm_builder builder;
13223 /* Create a vec_perm_indices for the integer vector. */
13228 }
13232 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
13235 {
13241 wide_int tem2
13245 }
13250 {
13252 unsigned HOST_WIDE_INT elsize
13255 {
13261 {
13267 }
13268 }
13269 }
13275 }
13277 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
13278 of an array (or vector). *CTOR_IDX if non-NULL is updated with the
13279 constructor element index of the value returned. If the element is
13280 not found NULL_TREE is returned and *CTOR_IDX is updated to
13281 the index of the element after the ACCESS_INDEX position (which
13282 may be outside of the CTOR array). */
13284 tree
13287 {
13293 {
13296 {
13297 /* Static constructors for variably sized objects makes no sense. */
13300 /* ??? When it is obvious that the range is signed, treat it so. */
13305 {
13307 low_bound
13309 SIGNED);
13310 }
13311 else
13312 {
13315 }
13316 }
13317 }
13321 index_sgn);
13333 {
13334 /* Array constructor might explicitly set index, or specify a range,
13335 or leave index NULL meaning that it is next index after previous
13336 one. */
13338 {
13340 max_index = index
13342 else
13343 {
13346 index_sgn);
13347 max_index
13349 index_sgn);
13351 }
13352 }
13354 {
13360 }
13361 else
13364 /* Do we have match? */
13366 {
13368 {
13372 }
13373 }
13375 /* We're past the element we search for. Note during parsing
13376 the elements might not be sorted.
13377 ??? We should use a binary search and a flag on the
13378 CONSTRUCTOR as to whether elements are sorted in declaration
13379 order. */
13381 }
13385 }
13387 /* Perform constant folding and related simplification of EXPR.
13388 The related simplifications include x*1 => x, x*0 => 0, etc.,
13389 and application of the associative law.
13390 NOP_EXPR conversions may be removed freely (as long as we
13391 are careful not to change the type of the overall expression).
13392 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13393 but we can constant-fold them if they have constant operands. */
13395 #ifdef ENABLE_FOLD_CHECKING
13396 # define fold(x) fold_1 (x)
13398 static
13399 #endif
13400 tree
13402 {
13406 tree tem;
13409 /* Return right away if a constant. */
13413 /* CALL_EXPR-like objects with variable numbers of operands are
13414 treated specially. */
13416 {
13418 {
13421 }
13423 }
13426 {
13431 {
13449 }
13450 }
13453 {
13455 {
13462 {
13467 }
13470 }
13472 /* Return a VECTOR_CST if possible. */
13474 {
13480 tree val;
13486 }
13494 }
13496 #ifdef ENABLE_FOLD_CHECKING
13497 #undef fold
13504 /* When --enable-checking=fold, compute a digest of expr before
13505 and after actual fold call to see if fold did not accidentally
13506 change original expr. */
13508 tree
13510 {
13511 tree ret;
13531 }
13533 void
13535 {
13546 }
13548 static void
13550 {
13552 }
13554 static void
13557 {
13563 recursive_label:
13573 {
13574 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
13582 }
13590 {
13591 /* Allow these fields to be modified. */
13592 tree tmp;
13603 {
13606 }
13607 }
13609 {
13610 /* Allow the no-warning bit to be set. Perhaps we shouldn't allow
13611 that and change builtins.cc etc. instead - see PR89543. */
13617 }
13628 {
13631 {
13647 }
13651 {
13664 }
13681 {
13687 }
13690 {
13692 {
13695 }
13697 }
13708 {
13711 }
13721 }
13722 }
13724 /* Helper function for outputting the checksum of a tree T. When
13725 debugging with gdb, you can "define mynext" to be "next" followed
13726 by "call debug_fold_checksum (op0)", then just trace down till the
13727 outputs differ. */
13729 DEBUG_FUNCTION void
13731 {
13746 }
13748 #endif
13750 /* Fold a unary tree expression with code CODE of type TYPE with an
13751 operand OP0. LOC is the location of the resulting expression.
13752 Return a folded expression if successful. Otherwise, return a tree
13753 expression with code CODE of type TYPE with an operand OP0. */
13755 tree
13758 {
13759 tree tem;
13760 #ifdef ENABLE_FOLD_CHECKING
13769 #endif
13775 #ifdef ENABLE_FOLD_CHECKING
13782 #endif
13784 }
13786 /* Fold a binary tree expression with code CODE of type TYPE with
13787 operands OP0 and OP1. LOC is the location of the resulting
13788 expression. Return a folded expression if successful. Otherwise,
13789 return a tree expression with code CODE of type TYPE with operands
13790 OP0 and OP1. */
13792 tree
13795 MEM_STAT_DECL)
13796 {
13797 tree tem;
13798 #ifdef ENABLE_FOLD_CHECKING
13815 #endif
13821 #ifdef ENABLE_FOLD_CHECKING
13836 #endif
13838 }
13840 /* Fold a ternary tree expression with code CODE of type TYPE with
13841 operands OP0, OP1, and OP2. Return a folded expression if
13842 successful. Otherwise, return a tree expression with code CODE of
13843 type TYPE with operands OP0, OP1, and OP2. */
13845 tree
13848 {
13849 tree tem;
13850 #ifdef ENABLE_FOLD_CHECKING
13874 #endif
13881 #ifdef ENABLE_FOLD_CHECKING
13904 #endif
13906 }
13908 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
13909 arguments in ARGARRAY, and a null static chain.
13910 Return a folded expression if successful. Otherwise, return a CALL_EXPR
13911 of type TYPE from the given operands as constructed by build_call_array. */
13913 tree
13916 {
13917 tree tem;
13918 #ifdef ENABLE_FOLD_CHECKING
13937 #endif
13943 #ifdef ENABLE_FOLD_CHECKING
13959 #endif
13961 }
13963 /* Perform constant folding and related simplification of initializer
13964 expression EXPR. These behave identically to "fold_buildN" but ignore
13965 potential run-time traps and exceptions that fold must preserve. */
13967 #define START_FOLD_INIT \
13968 int saved_signaling_nans = flag_signaling_nans;\
13969 int saved_trapping_math = flag_trapping_math;\
13970 int saved_rounding_math = flag_rounding_math;\
13971 int saved_trapv = flag_trapv;\
13972 int saved_folding_initializer = folding_initializer;\
13973 flag_signaling_nans = 0;\
13974 flag_trapping_math = 0;\
13975 flag_rounding_math = 0;\
13976 flag_trapv = 0;\
13977 folding_initializer = 1;
13979 #define END_FOLD_INIT \
13980 flag_signaling_nans = saved_signaling_nans;\
13981 flag_trapping_math = saved_trapping_math;\
13982 flag_rounding_math = saved_rounding_math;\
13983 flag_trapv = saved_trapv;\
13984 folding_initializer = saved_folding_initializer;
13986 tree
13988 {
13989 tree result;
13990 START_FOLD_INIT;
13994 END_FOLD_INIT;
13996 }
13998 tree
14001 {
14002 tree result;
14003 START_FOLD_INIT;
14007 END_FOLD_INIT;
14009 }
14011 tree
14014 {
14015 tree result;
14016 START_FOLD_INIT;
14020 END_FOLD_INIT;
14022 }
14024 tree
14027 {
14028 tree result;
14029 START_FOLD_INIT;
14033 END_FOLD_INIT;
14035 }
14037 tree
14040 {
14041 tree result;
14042 START_FOLD_INIT;
14046 END_FOLD_INIT;
14048 }
14050 #undef START_FOLD_INIT
14051 #undef END_FOLD_INIT
14053 /* Determine if first argument is a multiple of second argument. Return 0 if
14054 it is not, or we cannot easily determined it to be.
14056 An example of the sort of thing we care about (at this point; this routine
14057 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14058 fold cases do now) is discovering that
14060 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14062 is a multiple of
14064 SAVE_EXPR (J * 8)
14066 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14068 This code also handles discovering that
14070 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14072 is a multiple of 8 so we don't have to worry about dealing with a
14073 possible remainder.
14075 Note that we *look* inside a SAVE_EXPR only to determine how it was
14076 calculated; it is not safe for fold to do much of anything else with the
14077 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14078 at run time. For example, the latter example above *cannot* be implemented
14079 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14080 evaluation time of the original SAVE_EXPR is not necessarily the same at
14081 the time the new expression is evaluated. The only optimization of this
14082 sort that would be valid is changing
14084 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14086 divided by 8 to
14088 SAVE_EXPR (I) * SAVE_EXPR (J)
14090 (where the same SAVE_EXPR (J) is used in the original and the
14091 transformed version).
14093 NOWRAP specifies whether all outer operations in TYPE should
14094 be considered not wrapping. Any type conversion within TOP acts
14095 as a barrier and we will fall back to NOWRAP being false.
14096 NOWRAP is mostly used to treat expressions in TYPE_SIZE and friends
14097 as not wrapping even though they are generally using unsigned arithmetic. */
14099 int
14101 {
14112 {
14114 /* Bitwise and provides a power of two multiple. If the mask is
14115 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14122 /* If the multiplication can wrap we cannot recurse further unless
14123 the bottom is a power of two which is where wrapping does not
14124 matter. */
14130 {
14136 {
14139 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
14141 {
14145 {
14148 }
14149 }
14151 }
14152 }
14157 /* Handle X << CST as X * (1 << CST) and only process the constant. */
14159 {
14162 {
14163 wide_int mul_op
14167 nowrap);
14168 }
14169 }
14174 /* If the addition or subtraction can wrap we cannot recurse further
14175 unless bottom is a power of two which is where wrapping does not
14176 matter. */
14182 /* Handle cases like op0 + 0xfffffffd as op0 - 3 if the expression has
14183 unsigned type. For example, (X / 3) + 0xfffffffd is multiple of 3,
14184 but 0xfffffffd is not. */
14187 && nowrap
14192 /* It is impossible to prove if op0 +- op1 is multiple of bottom
14193 precisely, so be conservative here checking if both op0 and op1
14194 are multiple of bottom. Note we check the second operand first
14195 since it's usually simpler. */
14199 CASE_CONVERT:
14200 /* Can't handle conversions from non-integral or wider integral type. */
14205 /* NOWRAP only extends to operations in the outermost type so
14206 make sure to strip it off here. */
14221 SIGNED);
14227 {
14230 /* Check for special cases to see if top is defined as multiple
14231 of bottom:
14233 top = (X & ~(bottom - 1) ; bottom is power of 2
14235 or
14237 Y = X % bottom
14238 top = X - Y. */
14257 }
14259 /* fall through */
14267 }
14268 }
14270 /* Return true if expression X cannot be (or contain) a NaN or infinity.
14271 This function returns true for integer expressions, and returns
14272 false if uncertain. */
14274 bool
14276 {
14281 {
14304 {
14305 CASE_CFN_FABS:
14307 CASE_CFN_FMAX:
14308 CASE_CFN_FMIN:
14313 }
14317 }
14318 }
14320 /* Return true if expression X evaluates to an infinity.
14321 This function returns false for integer expressions. */
14323 bool
14325 {
14329 {
14342 }
14343 }
14345 /* Return true if expression X could evaluate to an infinity.
14346 This function returns false for integer expressions, and returns
14347 true if uncertain. */
14349 bool
14351 {
14355 {
14368 }
14369 }
14371 /* Return true if expression X evaluates to a signaling NaN.
14372 This function returns false for integer expressions. */
14374 bool
14376 {
14380 {
14391 }
14392 }
14394 /* Return true if expression X could evaluate to a signaling NaN.
14395 This function returns false for integer expressions, and returns
14396 true if uncertain. */
14398 bool
14400 {
14404 {
14424 {
14425 CASE_CFN_FABS:
14427 CASE_CFN_FMAX:
14428 CASE_CFN_FMIN:
14433 }
14436 }
14437 }
14439 /* Return true if expression X evaluates to a NaN.
14440 This function returns false for integer expressions. */
14442 bool
14444 {
14448 {
14459 }
14460 }
14462 /* Return true if expression X could evaluate to a NaN.
14463 This function returns false for integer expressions, and returns
14464 true if uncertain. */
14466 bool
14468 {
14472 {
14497 {
14498 CASE_CFN_FABS:
14500 CASE_CFN_FMAX:
14501 CASE_CFN_FMIN:
14506 }
14509 }
14510 }
14512 /* Return true if expression X could evaluate to -0.0.
14513 This function returns true if uncertain. */
14515 bool
14517 {
14521 {
14536 {
14537 CASE_CFN_FABS:
14541 }
14544 }
14545 /* Ideally !(tree_expr_nonzero_p (X) || tree_expr_nonnegative_p (X))
14546 * but currently those predicates require tree and not const_tree. */
14548 }
14550 #define tree_expr_nonnegative_warnv_p(X, Y) \
14553 #define RECURSE(X) \
14554 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
14556 /* Return true if CODE or TYPE is known to be non-negative. */
14558 static bool
14560 {
14563 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14564 have a signed:1 type (where the value is -1 and 0). */
14567 }
14569 /* Return true if (CODE OP0) is known to be non-negative. If the return
14570 value is based on the assumption that signed overflow is undefined,
14571 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14572 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14574 bool
14577 {
14582 {
14584 /* We can't return 1 if flag_wrapv is set because
14585 ABS_EXPR<INT_MIN> = INT_MIN. */
14589 {
14592 }
14600 CASE_CONVERT:
14601 {
14606 {
14610 {
14614 }
14615 }
14617 {
14623 }
14624 }
14629 }
14631 /* We don't know sign of `t', so be conservative and return false. */
14633 }
14635 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14636 value is based on the assumption that signed overflow is undefined,
14637 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14638 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14640 bool
14644 {
14649 {
14655 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14656 both unsigned and at least 2 bits shorter than the result. */
14660 {
14665 {
14669 }
14670 }
14675 {
14676 /* x * x is always non-negative for floating point x
14677 or without overflow. */
14680 {
14685 }
14686 }
14688 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14689 both unsigned and their total bits is shorter than the result. */
14693 {
14712 {
14722 }
14723 }
14730 /* Usually RECURSE (op0) || RECURSE (op1) but NaNs complicate
14731 things. */
14756 }
14758 /* We don't know sign of `t', so be conservative and return false. */
14760 }
14762 /* Return true if T is known to be non-negative. If the return
14763 value is based on the assumption that signed overflow is undefined,
14764 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14765 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14767 bool
14769 {
14774 {
14788 /* Limit the depth of recursion to avoid quadratic behavior.
14789 This is expected to catch almost all occurrences in practice.
14790 If this code misses important cases that unbounded recursion
14791 would not, passes that need this information could be revised
14792 to provide it through dataflow propagation. */
14800 }
14801 }
14803 /* Return true if T is known to be non-negative. If the return
14804 value is based on the assumption that signed overflow is undefined,
14805 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14806 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14808 bool
14811 {
14813 {
14814 CASE_CFN_ACOS:
14815 CASE_CFN_ACOSH:
14816 CASE_CFN_CABS:
14817 CASE_CFN_COSH:
14818 CASE_CFN_ERFC:
14819 CASE_CFN_EXP:
14820 CASE_CFN_EXP10:
14821 CASE_CFN_EXP2:
14822 CASE_CFN_FABS:
14823 CASE_CFN_FDIM:
14824 CASE_CFN_HYPOT:
14825 CASE_CFN_POW10:
14826 CASE_CFN_FFS:
14827 CASE_CFN_PARITY:
14828 CASE_CFN_POPCOUNT:
14829 CASE_CFN_CLZ:
14830 CASE_CFN_CLRSB:
14835 /* Always true. */
14838 CASE_CFN_SQRT:
14839 CASE_CFN_SQRT_FN:
14840 /* sqrt(-0.0) is -0.0. */
14845 CASE_CFN_ASINH:
14846 CASE_CFN_ATAN:
14847 CASE_CFN_ATANH:
14848 CASE_CFN_CBRT:
14849 CASE_CFN_CEIL:
14850 CASE_CFN_CEIL_FN:
14851 CASE_CFN_ERF:
14852 CASE_CFN_EXPM1:
14853 CASE_CFN_FLOOR:
14854 CASE_CFN_FLOOR_FN:
14855 CASE_CFN_FMOD:
14856 CASE_CFN_FREXP:
14857 CASE_CFN_ICEIL:
14858 CASE_CFN_IFLOOR:
14859 CASE_CFN_IRINT:
14860 CASE_CFN_IROUND:
14861 CASE_CFN_LCEIL:
14862 CASE_CFN_LDEXP:
14863 CASE_CFN_LFLOOR:
14864 CASE_CFN_LLCEIL:
14865 CASE_CFN_LLFLOOR:
14866 CASE_CFN_LLRINT:
14867 CASE_CFN_LLROUND:
14868 CASE_CFN_LRINT:
14869 CASE_CFN_LROUND:
14870 CASE_CFN_MODF:
14871 CASE_CFN_NEARBYINT:
14872 CASE_CFN_NEARBYINT_FN:
14873 CASE_CFN_RINT:
14874 CASE_CFN_RINT_FN:
14875 CASE_CFN_ROUND:
14876 CASE_CFN_ROUND_FN:
14877 CASE_CFN_ROUNDEVEN:
14878 CASE_CFN_ROUNDEVEN_FN:
14879 CASE_CFN_SCALB:
14880 CASE_CFN_SCALBLN:
14881 CASE_CFN_SCALBN:
14882 CASE_CFN_SIGNBIT:
14883 CASE_CFN_SIGNIFICAND:
14884 CASE_CFN_SINH:
14885 CASE_CFN_TANH:
14886 CASE_CFN_TRUNC:
14887 CASE_CFN_TRUNC_FN:
14888 /* True if the 1st argument is nonnegative. */
14891 CASE_CFN_FMAX:
14892 CASE_CFN_FMAX_FN:
14893 /* Usually RECURSE (arg0) || RECURSE (arg1) but NaNs complicate
14894 things. In the presence of sNaNs, we're only guaranteed to be
14895 non-negative if both operands are non-negative. In the presence
14896 of qNaNs, we're non-negative if either operand is non-negative
14897 and can't be a qNaN, or if both operands are non-negative. */
14906 CASE_CFN_FMIN:
14907 CASE_CFN_FMIN_FN:
14908 /* True if the 1st AND 2nd arguments are nonnegative. */
14911 CASE_CFN_COPYSIGN:
14912 CASE_CFN_COPYSIGN_FN:
14913 /* True if the 2nd argument is nonnegative. */
14916 CASE_CFN_POWI:
14917 /* True if the 1st argument is nonnegative or the second
14918 argument is an even integer. */
14924 CASE_CFN_POW:
14925 /* True if the 1st argument is nonnegative or the second
14926 argument is an even integer valued real. */
14928 {
14929 REAL_VALUE_TYPE c;
14930 HOST_WIDE_INT n;
14935 {
14936 REAL_VALUE_TYPE cint;
14940 }
14941 }
14946 }
14948 }
14950 /* Return true if T is known to be non-negative. If the return
14951 value is based on the assumption that signed overflow is undefined,
14952 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14953 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
14955 static bool
14957 {
14963 {
14965 {
14969 /* If the initializer is non-void, then it's a normal expression
14970 that will be assigned to the slot. */
14974 /* Otherwise, the initializer sets the slot in some way. One common
14975 way is an assignment statement at the end of the initializer. */
14977 {
14985 else
14987 }
14993 }
14996 {
15002 arg0,
15003 arg1,
15005 }
15018 }
15019 }
15021 #undef RECURSE
15022 #undef tree_expr_nonnegative_warnv_p
15024 /* Return true if T is known to be non-negative. If the return
15025 value is based on the assumption that signed overflow is undefined,
15026 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15027 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
15029 bool
15031 {
15038 {
15060 }
15063 {
15089 }
15090 }
15092 /* Return true if `t' is known to be non-negative. Handle warnings
15093 about undefined signed overflow. */
15095 bool
15097 {
15104 "determining that expression is always "
15106 WARN_STRICT_OVERFLOW_MISC);
15108 }
15111 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15112 For floating point we further ensure that T is not denormal.
15113 Similar logic is present in nonzero_address in rtlanal.h.
15115 If the return value is based on the assumption that signed overflow
15116 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15117 change *STRICT_OVERFLOW_P. */
15119 bool
15122 {
15124 {
15127 strict_overflow_p);
15130 {
15136 strict_overflow_p));
15137 }
15142 strict_overflow_p);
15146 }
15149 }
15151 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15152 For floating point we further ensure that T is not denormal.
15153 Similar logic is present in nonzero_address in rtlanal.h.
15155 If the return value is based on the assumption that signed overflow
15156 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15157 change *STRICT_OVERFLOW_P. */
15159 bool
15161 tree type,
15162 tree op0,
15164 {
15167 {
15171 {
15172 /* With the presence of negative values it is hard
15173 to say something. */
15180 /* One of operands must be positive and the other non-negative. */
15181 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15182 overflows, on a twos-complement machine the sum of two
15183 nonnegative numbers can never be zero. */
15185 strict_overflow_p)
15187 strict_overflow_p));
15188 }
15193 {
15195 strict_overflow_p)
15197 strict_overflow_p))
15198 {
15201 }
15202 }
15211 {
15214 }
15221 {
15225 /* When both operands are nonzero, then MAX must be too. */
15227 strict_overflow_p))
15230 /* MAX where operand 0 is positive is positive. */
15232 strict_overflow_p);
15233 }
15234 /* MAX where operand 1 is positive is positive. */
15239 {
15243 }
15248 strict_overflow_p)
15250 strict_overflow_p));
15254 }
15257 }
15259 /* Return true when T is an address and is known to be nonzero.
15260 For floating point we further ensure that T is not denormal.
15261 Similar logic is present in nonzero_address in rtlanal.h.
15263 If the return value is based on the assumption that signed overflow
15264 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15265 change *STRICT_OVERFLOW_P. */
15267 bool
15269 {
15272 {
15277 {
15289 /* For objects in symbol table check if we know they are non-zero.
15290 Don't do anything for variables and functions before symtab is built;
15291 it is quite possible that they will be declared weak later. */
15296 /* Constants are never weak. */
15301 }
15309 {
15313 }
15323 }
15325 }
15327 #define integer_valued_real_p(X) \
15330 #define RECURSE(X) \
15331 ((integer_valued_real_p) (X, depth + 1))
15333 /* Return true if the floating point result of (CODE OP0) has an
15334 integer value. We also allow +Inf, -Inf and NaN to be considered
15335 integer values. Return false for signaling NaN.
15337 DEPTH is the current nesting depth of the query. */
15339 bool
15341 {
15343 {
15350 CASE_CONVERT:
15351 {
15358 }
15362 }
15364 }
15366 /* Return true if the floating point result of (CODE OP0 OP1) has an
15367 integer value. We also allow +Inf, -Inf and NaN to be considered
15368 integer values. Return false for signaling NaN.
15370 DEPTH is the current nesting depth of the query. */
15372 bool
15374 {
15376 {
15386 }
15388 }
15390 /* Return true if the floating point result of calling FNDECL with arguments
15391 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
15392 considered integer values. Return false for signaling NaN. If FNDECL
15393 takes fewer than 2 arguments, the remaining ARGn are null.
15395 DEPTH is the current nesting depth of the query. */
15397 bool
15399 {
15401 {
15402 CASE_CFN_CEIL:
15403 CASE_CFN_CEIL_FN:
15404 CASE_CFN_FLOOR:
15405 CASE_CFN_FLOOR_FN:
15406 CASE_CFN_NEARBYINT:
15407 CASE_CFN_NEARBYINT_FN:
15408 CASE_CFN_RINT:
15409 CASE_CFN_RINT_FN:
15410 CASE_CFN_ROUND:
15411 CASE_CFN_ROUND_FN:
15412 CASE_CFN_ROUNDEVEN:
15413 CASE_CFN_ROUNDEVEN_FN:
15414 CASE_CFN_TRUNC:
15415 CASE_CFN_TRUNC_FN:
15418 CASE_CFN_FMIN:
15419 CASE_CFN_FMIN_FN:
15420 CASE_CFN_FMAX:
15421 CASE_CFN_FMAX_FN:
15426 }
15428 }
15430 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
15431 has an integer value. We also allow +Inf, -Inf and NaN to be
15432 considered integer values. Return false for signaling NaN.
15434 DEPTH is the current nesting depth of the query. */
15436 bool
15438 {
15440 {
15448 /* Limit the depth of recursion to avoid quadratic behavior.
15449 This is expected to catch almost all occurrences in practice.
15450 If this code misses important cases that unbounded recursion
15451 would not, passes that need this information could be revised
15452 to provide it through dataflow propagation. */
15456 depth));
15460 }
15462 }
15464 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
15465 has an integer value. We also allow +Inf, -Inf and NaN to be
15466 considered integer values. Return false for signaling NaN.
15468 DEPTH is the current nesting depth of the query. */
15470 static bool
15472 {
15474 {
15485 }
15487 }
15489 #undef RECURSE
15490 #undef integer_valued_real_p
15492 /* Return true if the floating point expression T has an integer value.
15493 We also allow +Inf, -Inf and NaN to be considered integer values.
15494 Return false for signaling NaN.
15496 DEPTH is the current nesting depth of the query. */
15498 bool
15500 {
15508 {
15524 }
15527 {
15533 {
15542 }
15546 }
15547 }
15549 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15550 attempt to fold the expression to a constant without modifying TYPE,
15551 OP0 or OP1.
15553 If the expression could be simplified to a constant, then return
15554 the constant. If the expression would not be simplified to a
15555 constant, then return NULL_TREE. */
15557 tree
15559 {
15562 }
15564 /* Given the components of a unary expression CODE, TYPE and OP0,
15565 attempt to fold the expression to a constant without modifying
15566 TYPE or OP0.
15568 If the expression could be simplified to a constant, then return
15569 the constant. If the expression would not be simplified to a
15570 constant, then return NULL_TREE. */
15572 tree
15574 {
15577 }
15579 /* If EXP represents referencing an element in a constant string
15580 (either via pointer arithmetic or array indexing), return the
15581 tree representing the value accessed, otherwise return NULL. */
15583 tree
15585 {
15589 {
15591 tree index;
15592 tree string;
15597 else
15598 {
15602 /* Optimize the special-case of a zero lower bound.
15604 We convert the low_bound to sizetype to avoid some problems
15605 with constant folding. (E.g. suppose the lower bound is 1,
15606 and its mode is QI. Without the conversion,l (ARRAY
15607 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15608 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15614 }
15616 scalar_int_mode char_mode;
15628 }
15630 }
15632 /* Folds a read from vector element at IDX of vector ARG. */
15634 tree
15636 {
15641 {
15645 {
15652 }
15653 }
15655 }
15657 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15658 an integer constant, real, or fixed-point constant.
15660 TYPE is the type of the result. */
15662 static tree
15664 {
15668 {
15674 {
15675 FIXED_VALUE_TYPE f;
15680 /* Propagate overflow flags. */
15684 }
15688 {
15695 }
15698 }
15701 }
15703 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15704 an integer constant or real constant.
15706 TYPE is the type of the result. */
15708 tree
15710 {
15714 {
15716 {
15717 /* If the value is unsigned or non-negative, then the absolute value
15718 is the same as the ordinary value. */
15722 ;
15724 /* If the value is negative, then the absolute value is
15725 its negation. */
15726 else
15729 /* Force to the destination type, set TREE_OVERFLOW for signed
15730 TYPE only. */
15732 }
15738 else
15744 }
15747 }
15749 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15750 constant. TYPE is the type of the result. */
15752 static tree
15754 {
15758 }
15760 /* Given CODE, a relational operator, the target type, TYPE and two
15761 constant operands OP0 and OP1, return the result of the
15762 relational operation. If the result is not a compile time
15763 constant, then return NULL_TREE. */
15765 static tree
15767 {
15770 /* From here on, the only cases we handle are when the result is
15771 known to be a constant. */
15774 {
15778 /* Handle the cases where either operand is a NaN. */
15780 {
15782 {
15810 }
15813 }
15816 }
15819 {
15823 }
15825 /* Handle equality/inequality of complex constants. */
15827 {
15838 else
15840 }
15843 {
15845 {
15846 /* Have vector comparison with scalar boolean result. */
15854 {
15862 }
15864 }
15865 tree_vector_builder elts;
15870 {
15883 }
15886 }
15888 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15890 To compute GT, swap the arguments and do LT.
15891 To compute GE, do LT and invert the result.
15892 To compute LE, swap the arguments, do LT and invert the result.
15893 To compute NE, do EQ and invert the result.
15895 Therefore, the code below must handle only EQ and LT. */
15898 {
15901 }
15903 /* Note that it is safe to invert for real values here because we
15904 have already handled the one case that it matters. */
15908 {
15911 }
15913 /* Compute a result for LT or EQ if args permit;
15914 Otherwise return T. */
15916 {
15919 else
15921 }
15922 else
15928 }
15930 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15931 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15932 itself. */
15934 tree
15936 {
15937 /* If the expression does not have side effects then we don't have to wrap
15938 it with a cleanup point expression. */
15942 /* If the expression is a return, check to see if the expression inside the
15943 return has no side effects or the right hand side of the modify expression
15944 inside the return. If either don't have side effects set we don't need to
15945 wrap the expression in a cleanup point expression. Note we don't check the
15946 left hand side of the modify because it should always be a return decl. */
15948 {
15955 }
15958 }
15960 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15961 of an indirection through OP0, or NULL_TREE if no simplification is
15962 possible. */
15964 tree
15966 {
15968 tree subtype;
15969 poly_uint64 const_op01;
15978 {
15982 /* *&CONST_DECL -> to the value of the const decl. */
15985 /* *&p => p; make sure to handle *&"str"[cst] here. */
15987 {
15991 else
15993 }
15994 /* *(foo *)&fooarray => fooarray[0] */
15997 && (!in_gimple_form
15999 {
16009 }
16010 /* *(foo *)&complexfoo => __real__ complexfoo */
16014 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16017 {
16021 index);
16022 }
16023 }
16027 {
16033 {
16034 tree op00type;
16038 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16041 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
16042 but we want to treat offsets with MSB set as negative.
16043 For the code below negative offsets are invalid and
16044 TYPE_SIZE of the element is something unsigned, so
16045 check whether op01 fits into poly_int64, which implies
16046 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
16047 then just use poly_uint64 because we want to treat the
16048 value as unsigned. */
16050 {
16052 poly_uint64 max_offset
16056 {
16061 }
16062 }
16063 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16066 {
16068 const_op01))
16070 }
16071 /* ((foo *)&fooarray)[1] => fooarray[1] */
16074 {
16083 {
16088 }
16089 }
16090 }
16091 }
16093 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16096 && (!in_gimple_form
16098 {
16099 tree type_domain;
16109 NULL_TREE);
16110 }
16113 }
16115 /* Builds an expression for an indirection through T, simplifying some
16116 cases. */
16118 tree
16120 {
16128 }
16130 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16132 tree
16134 {
16139 else
16141 }
16143 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16144 whose result is ignored. The type of the returned tree need not be
16145 the same as the original expression. */
16147 tree
16149 {
16155 {
16166 else
16172 {
16188 }
16193 }
16194 }
16196 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16198 tree
16200 {
16206 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16207 have to do anything. Only do this when we are not given a const,
16208 because in that case, this check is more expensive than just
16209 doing it. */
16211 {
16216 }
16218 /* If divisor is a power of two, simplify this to bit manipulation. */
16220 {
16222 {
16236 }
16237 else
16238 {
16239 tree t;
16245 }
16246 }
16247 else
16248 {
16253 }
16256 }
16258 /* Likewise, but round down. */
16260 tree
16262 {
16269 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16270 have to do anything. Only do this when we are not given a const,
16271 because in that case, this check is more expensive than just
16272 doing it. */
16274 {
16279 }
16281 /* If divisor is a power of two, simplify this to bit manipulation. */
16283 {
16284 tree t;
16288 }
16289 else
16290 {
16295 }
16298 }
16300 /* Returns the pointer to the base of the object addressed by EXP and
16301 extracts the information about the offset of the access, storing it
16302 to PBITPOS and POFFSET. */
16304 static tree
16307 {
16308 tree core;
16309 machine_mode mode;
16311 poly_int64 bitsize;
16315 {
16320 }
16322 {
16328 {
16329 poly_offset_int tem
16335 }
16336 }
16337 else
16338 {
16342 }
16345 }
16347 /* Returns true if addresses of E1 and E2 differ by a constant, false
16348 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16350 bool
16352 {
16367 {
16377 }
16379 {
16380 /* If only one of the offsets is non-constant, the difference cannot
16381 be a constant. */
16383 }
16384 else
16389 }
16391 /* Return OFF converted to a pointer offset type suitable as offset for
16392 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16393 tree
16395 {
16399 }
16401 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16402 tree
16404 {
16407 }
16409 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16410 tree
16412 {
16415 }
16417 /* Return a pointer to a NUL-terminated string containing the sequence
16418 of bytes corresponding to the representation of the object referred to
16419 by SRC (or a subsequence of such bytes within it if SRC is a reference
16420 to an initialized constant array plus some constant offset).
16421 Set *STRSIZE the number of bytes in the constant sequence including
16422 the terminating NUL byte. *STRSIZE is equal to sizeof(A) - OFFSET
16423 where A is the array that stores the constant sequence that SRC points
16424 to and OFFSET is the byte offset of SRC from the beginning of A. SRC
16425 need not point to a string or even an array of characters but may point
16426 to an object of any type. */
16430 {
16431 /* The offset into the array A storing the string, and A's byte size. */
16432 tree offset_node;
16433 tree mem_size;
16440 else
16447 {
16450 else
16452 }
16457 /* ARRAY_SIZE is the byte size of the array the constant sequence
16458 is stored in and equal to sizeof A. INIT_BYTES is the number
16459 of bytes in the constant sequence used to initialize the array,
16460 including any embedded NULs as well as the terminating NUL (for
16461 strings), but not including any trailing zeros/NULs past
16462 the terminating one appended implicitly to a string literal to
16463 zero out the remainder of the array it's stored in. For example,
16464 given:
16465 const char a[7] = "abc\0d";
16466 n = strlen (a + 1);
16467 ARRAY_SIZE is 7, INIT_BYTES is 6, and OFFSET is 1. For a valid
16468 (i.e., nul-terminated) string with no embedded nuls, INIT_BYTES
16469 is equal to strlen (A) + 1. */
16474 /* Ideally this would turn into a gcc_checking_assert over time. */
16482 {
16483 /* Compute and store the number of characters from the beginning
16484 of the substring at OFFSET to the end, including the terminating
16485 nul. Offsets past the initial length refer to null strings. */
16488 else
16490 }
16491 else
16492 {
16494 /* Support only properly NUL-terminated single byte strings. */
16499 }
16502 }
16504 /* Return a pointer to a NUL-terminated string corresponding to
16505 the expression STR referencing a constant string, possibly
16506 involving a constant offset. Return null if STR either doesn't
16507 reference a constant string or if it involves a nonconstant
16508 offset. */
16512 {
16514 }
16516 /* Given a tree T, compute which bits in T may be nonzero. */
16518 wide_int
16520 {
16522 {
16540 CASE_CONVERT:
16546 {
16551 }
16555 {
16563 }
16567 {
16575 }
16579 }
16582 }
16584 /* Helper function for address compare simplifications in match.pd.
16585 OP0 and OP1 are ADDR_EXPR operands being compared by CODE.
16586 TYPE is the type of comparison operands.
16587 BASE0, BASE1, OFF0 and OFF1 are set by the function.
16588 GENERIC is true if GENERIC folding and false for GIMPLE folding.
16589 Returns 0 if OP0 is known to be unequal to OP1 regardless of OFF{0,1},
16590 1 if bases are known to be equal and OP0 cmp OP1 depends on OFF0 cmp OFF1,
16591 and 2 if unknown. */
16593 int
16597 {
16603 {
16606 }
16608 {
16611 }
16616 /* Punt in GENERIC on variables with value expressions;
16617 the value expressions might point to fields/elements
16618 of other vars etc. */
16624 {
16628 }
16636 /* Assume different STRING_CSTs with the same content will be
16637 merged. */
16646 {
16649 /* If the offsets are equal we can ignore overflow. */
16652 /* Or if we compare using pointers to decls or strings. */
16657 }
16663 /* At this point we know (or assume) the two pointers point at
16664 different objects. */
16668 /* Punt on non-zero offsets from functions. */
16672 /* Or if the bases are neither decls nor string literals. */
16677 /* For initializers, assume addresses of different functions are
16678 different. */
16684 /* Compute whether one address points to the start of one
16685 object and another one to the end of another one. */
16688 {
16691 else
16693 }
16696 else
16697 {
16701 else
16703 }
16705 {
16708 else
16710 }
16713 else
16714 {
16718 else
16720 }
16722 {
16723 /* If one offset is pointing (or could be) to the beginning of one
16724 object and the other is pointing to one past the last byte of the
16725 other object, punt. */
16730 /* If both offsets are the same, there are some cases we know that are
16731 ok. Either if we know they aren't zero, or if we know both sizes
16732 are no zero. */
16738 }
16740 /* At this point, equal is 2 if either one or both pointers are out of
16741 bounds of their object, or one points to start of its object and the
16742 other points to end of its object. This is unspecified behavior
16743 e.g. in C++. Otherwise equal is 0. */
16747 /* When both pointers point to string literals, even when equal is 0,
16748 due to tail merging of string literals the pointers might be the same. */
16750 {
16757 /* If the bytes in the string literals starting at the pointers
16758 differ, the pointers need to be different. */
16763 {
16768 /* If even the bytes in the string literal before the
16769 pointers are the same, the string literals could be
16770 tail merged. */
16772 }
16774 }
16779 /* If this is a pointer comparison, ignore for now even
16780 valid equalities where one pointer is the offset zero
16781 of one object and the other to one past end of another one. */
16785 /* Assume that string literals can't be adjacent to variables
16786 (automatic or global). */
16790 /* Assume that automatic variables can't be adjacent to global
16791 variables. */
16796 }
16798 /* Return the single non-zero element of a CONSTRUCTOR or NULL_TREE. */
16799 tree
16801 {
16810 {
16814 }
16816 }
16818 #if CHECKING_P
16822 /* Helper functions for writing tests of folding trees. */
16824 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
16826 static void
16828 tree constant)
16829 {
16831 }
16833 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
16834 wrapping WRAPPED_EXPR. */
16836 static void
16838 tree wrapped_expr)
16839 {
16844 }
16846 /* Verify that various arithmetic binary operations are folded
16847 correctly. */
16849 static void
16851 {
16857 /* Addition. */
16858 /* 1 <-- (0 + 1) */
16860 one);
16862 one);
16864 /* (nonlvalue)x <-- (x + 0) */
16866 x);
16868 /* Subtraction. */
16869 /* 0 <-- (x - x) */
16871 zero);
16873 x);
16875 /* Multiplication. */
16876 /* 0 <-- (x * 0) */
16878 zero);
16880 /* (nonlvalue)x <-- (x * 1) */
16882 x);
16883 }
16885 /* Verify that various binary operations on vectors are folded
16886 correctly. */
16888 static void
16890 {
16897 /* Verify equality tests that return a scalar boolean result. */
16910 }
16912 /* Verify folding of VEC_DUPLICATE_EXPRs. */
16914 static void
16916 {
16919 /* This will be 1 if VEC_MODE isn't a vector mode. */
16926 }
16928 /* Run all of the selftests within this file. */
16930 void
16932 {
16936 }