| blob | fb664fee8be138ea7b6c954107c5fcf7810c365b |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide, size_binop
31 and force_fit_type_double.
33 fold takes a tree as argument and returns a simplified tree.
35 size_binop takes a tree code for an arithmetic operation
36 and two operands that are trees, and produces a tree for the
37 result, assuming the type comes from `sizetype'.
39 size_int takes an integer value, and creates a tree constant
40 with type from `sizetype'.
42 force_fit_type_double takes a constant, an overflowable flag and a
43 prior overflow indicator. It forces the value to fit the type and
44 sets TREE_OVERFLOW.
46 Note: Since the folders get called on non-gimple code as well as
47 gimple code, we need to handle GIMPLE tuples as well as their
48 corresponding tree equivalents. */
68 /* Nonzero if we are folding constants inside an initializer; zero
69 otherwise. */
72 /* The following constants represent a bit based encoding of GCC's
73 comparison operators. This encoding simplifies transformations
74 on relational comparison operators, such as AND and OR. */
92 };
126 tree);
148 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
149 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
150 and SUM1. Then this yields nonzero if overflow occurred during the
151 addition.
153 Overflow occurs if A and B have the same sign, but A and SUM differ in
154 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
155 sign. */
156 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
157 \f
158 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
159 We do that by representing the two-word integer in 4 words, with only
160 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
161 number. The value of the word is LOWPART + HIGHPART * BASE. */
163 #define LOWPART(x) \
164 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
165 #define HIGHPART(x) \
166 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
167 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
169 /* Unpack a two-word integer into 4 words.
170 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
171 WORDS points to the array of HOST_WIDE_INTs. */
173 static void
175 {
180 }
182 /* Pack an array of 4 words into a two-word integer.
183 WORDS points to the array of words.
184 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
186 static void
189 {
192 }
193 \f
194 /* Force the double-word integer L1, H1 to be within the range of the
195 integer type TYPE. Stores the properly truncated and sign-extended
196 double-word integer in *LV, *HV. Returns true if the operation
197 overflows, that is, argument and result are different. */
199 int
202 {
211 else
214 /* Size types *are* sign extended. */
219 /* First clear all bits that are beyond the type's precision. */
221 ;
224 else
225 {
229 }
231 /* Then do sign extension if necessary. */
237 {
238 /* Sign extend top half? */
242 }
244 {
247 }
248 else
249 {
250 /* Sign extend bottom half? */
252 {
255 }
256 }
261 /* If the value didn't fit, signal overflow. */
263 }
265 /* We force the double-int HIGH:LOW to the range of the type TYPE by
266 sign or zero extending it.
267 OVERFLOWABLE indicates if we are interested
268 in overflow of the value, when >0 we are only interested in signed
269 overflow, for <0 we are interested in any overflow. OVERFLOWED
270 indicates whether overflow has already occurred. CONST_OVERFLOWED
271 indicates whether constant overflow has already occurred. We force
272 T's value to be within range of T's type (by setting to 0 or 1 all
273 the bits outside the type's range). We set TREE_OVERFLOWED if,
274 OVERFLOWED is nonzero,
275 or OVERFLOWABLE is >0 and signed overflow occurs
276 or OVERFLOWABLE is <0 and any overflow occurs
277 We return a new tree node for the extended double-int. The node
278 is shared if no overflow flags are set. */
280 tree
284 {
288 /* Size types *are* sign extended. */
295 /* If we need to set overflow flags, return a new unshared node. */
297 {
301 {
308 }
309 }
311 /* Else build a shared node. */
313 }
314 \f
315 /* Add two doubleword integers with doubleword result.
316 Return nonzero if the operation overflows according to UNSIGNED_P.
317 Each argument is given as two `HOST_WIDE_INT' pieces.
318 One argument is L1 and H1; the other, L2 and H2.
319 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
321 int
326 {
328 HOST_WIDE_INT h;
338 else
340 }
342 /* Negate a doubleword integer with doubleword result.
343 Return nonzero if the operation overflows, assuming it's signed.
344 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
345 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
347 int
350 {
352 {
356 }
357 else
358 {
362 }
363 }
364 \f
365 /* Multiply two doubleword integers with doubleword result.
366 Return nonzero if the operation overflows according to UNSIGNED_P.
367 Each argument is given as two `HOST_WIDE_INT' pieces.
368 One argument is L1 and H1; the other, L2 and H2.
369 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
371 int
376 {
391 {
394 {
396 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
398 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
402 }
404 }
409 /* Unsigned overflow is immediate. */
413 /* Check for signed overflow by calculating the signed representation of the
414 top half of the result; it should agree with the low half's sign bit. */
416 {
419 }
421 {
424 }
426 }
427 \f
428 /* Shift the doubleword integer in L1, H1 left by COUNT places
429 keeping only PREC bits of result.
430 Shift right if COUNT is negative.
431 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
432 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
434 void
438 {
442 {
445 }
451 {
452 /* Shifting by the host word size is undefined according to the
453 ANSI standard, so we must handle this as a special case. */
456 }
458 {
461 }
462 else
463 {
467 }
469 /* Sign extend all bits that are beyond the precision. */
477 ;
479 {
482 }
483 else
484 {
488 }
489 }
491 /* Shift the doubleword integer in L1, H1 right by COUNT places
492 keeping only PREC bits of result. COUNT must be positive.
493 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
494 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
496 void
501 {
504 signmask = (arith
512 {
513 /* Shifting by the host word size is undefined according to the
514 ANSI standard, so we must handle this as a special case. */
517 }
519 {
522 }
523 else
524 {
528 }
530 /* Zero / sign extend all bits that are beyond the precision. */
533 {
536 }
538 ;
540 {
543 }
544 else
545 {
549 }
550 }
551 \f
552 /* Rotate the doubleword integer in L1, H1 left by COUNT places
553 keeping only PREC bits of result.
554 Rotate right if COUNT is negative.
555 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
557 void
561 {
573 }
575 /* Rotate the doubleword integer in L1, H1 left by COUNT places
576 keeping only PREC bits of result. COUNT must be positive.
577 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
579 void
583 {
595 }
596 \f
597 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
598 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
599 CODE is a tree code for a kind of division, one of
600 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
601 or EXACT_DIV_EXPR
602 It controls how the quotient is rounded to an integer.
603 Return nonzero if the operation overflows.
604 UNS nonzero says do unsigned division. */
606 int
609 HOST_WIDE_INT hnum_orig,
611 HOST_WIDE_INT hden_orig,
615 {
631 /* Calculate quotient sign and convert operands to unsigned. */
633 {
635 {
637 /* (minimum integer) / (-1) is the only overflow case. */
641 }
643 {
646 }
647 }
652 /* This unsigned division rounds toward zero. */
655 }
659 /* hden != 0 already checked. */
664 }
674 /* Special code for when the divisor < BASE. */
676 {
677 /* hnum != 0 already checked. */
679 {
683 }
684 }
685 else
686 {
687 /* Full double precision division,
688 with thanks to Don Knuth's "Seminumerical Algorithms". */
692 /* Find the highest nonzero divisor digit. */
695 {
698 }
700 /* Insure that the first digit of the divisor is at least BASE/2.
701 This is required by the quotient digit estimation algorithm. */
708 {
712 }
717 {
722 }
723 }
727 /* Main loop */
729 {
730 /* Guess the next quotient digit, quo_est, by dividing the first
731 two remaining dividend digits by the high order quotient digit.
732 quo_est is never low and is at most 2 high. */
739 else
742 /* Refine quo_est so it's usually correct, and at most one high. */
747 quo_est--;
749 /* Try QUO_EST as the quotient digit, by multiplying the
750 divisor by QUO_EST and subtracting from the remaining dividend.
751 Keep in mind that QUO_EST is the I - 1st digit. */
755 {
761 }
763 /* If quo_est was high by one, then num[i] went negative and
764 we need to correct things. */
766 {
767 quo_est--;
770 {
774 }
777 }
779 /* Store the quotient digit. */
781 }
782 }
786 finish_up:
787 /* If result is negative, make it so. */
791 /* Compute trial remainder: rem = num - (quo * den) */
797 {
806 {
807 /* quo = quo - 1; */
810 }
811 else
818 {
821 }
822 else
828 {
834 /* Get absolute values. */
840 /* If (2 * abs (lrem) >= abs (lden)) */
849 {
851 /* quo = quo - 1; */
854 else
855 /* quo = quo + 1; */
858 }
859 else
861 }
866 }
868 /* Compute true remainder: rem = num - (quo * den) */
873 }
875 /* If ARG2 divides ARG1 with zero remainder, carries out the division
876 of type CODE and returns the quotient.
877 Otherwise returns NULL_TREE. */
879 static tree
881 {
891 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
892 &obj[some_exotic_number]. */
894 {
898 type);
899 }
900 else
911 }
912 \f
913 /* This is nonzero if we should defer warnings about undefined
914 overflow. This facility exists because these warnings are a
915 special case. The code to estimate loop iterations does not want
916 to issue any warnings, since it works with expressions which do not
917 occur in user code. Various bits of cleanup code call fold(), but
918 only use the result if it has certain characteristics (e.g., is a
919 constant); that code only wants to issue a warning if the result is
920 used. */
924 /* If a warning about undefined overflow is deferred, this is the
925 warning. Note that this may cause us to turn two warnings into
926 one, but that is fine since it is sufficient to only give one
927 warning per expression. */
931 /* If a warning about undefined overflow is deferred, this is the
932 level at which the warning should be emitted. */
936 /* Start deferring overflow warnings. We could use a stack here to
937 permit nested calls, but at present it is not necessary. */
939 void
941 {
943 }
945 /* Stop deferring overflow warnings. If there is a pending warning,
946 and ISSUE is true, then issue the warning if appropriate. STMT is
947 the statement with which the warning should be associated (used for
948 location information); STMT may be NULL. CODE is the level of the
949 warning--a warn_strict_overflow_code value. This function will use
950 the smaller of CODE and the deferred code when deciding whether to
951 issue the warning. CODE may be zero to mean to always use the
952 deferred code. */
954 void
956 {
958 location_t locus;
963 {
969 }
977 /* Use the smallest code level when deciding to issue the
978 warning. */
987 else
990 }
992 /* Stop deferring overflow warnings, ignoring any deferred
993 warnings. */
995 void
997 {
999 }
1001 /* Whether we are deferring overflow warnings. */
1003 bool
1005 {
1007 }
1009 /* This is called when we fold something based on the fact that signed
1010 overflow is undefined. */
1012 static void
1014 {
1017 {
1020 {
1023 }
1024 }
1027 }
1028 \f
1029 /* Return true if the built-in mathematical function specified by CODE
1030 is odd, i.e. -f(x) == f(-x). */
1032 static bool
1034 {
1036 {
1070 }
1072 }
1074 /* Check whether we may negate an integer constant T without causing
1075 overflow. */
1077 bool
1079 {
1082 tree type;
1092 {
1097 }
1098 else
1103 }
1105 /* Determine whether an expression T can be cheaply negated using
1106 the function negate_expr without introducing undefined overflow. */
1108 static bool
1110 {
1111 tree type;
1120 {
1125 /* Check that -CST will not overflow type. */
1151 /* -(A + B) -> (-B) - A. */
1156 /* -(A + B) -> (-A) - B. */
1160 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1170 /* Fall through. */
1183 /* In general we can't negate A / B, because if A is INT_MIN and
1184 B is 1, we may turn this into INT_MIN / -1 which is undefined
1185 and actually traps on some architectures. But if overflow is
1186 undefined, we can negate, because - (INT_MIN / 1) is an
1187 overflow. */
1195 /* Negate -((double)float) as (double)(-float). */
1197 {
1201 }
1205 /* Negate -f(x) as f(-x). */
1211 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1213 {
1219 }
1224 }
1226 }
1228 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1229 simplification is possible.
1230 If negate_expr_p would return true for T, NULL_TREE will never be
1231 returned. */
1233 static tree
1235 {
1237 tree tem;
1240 {
1241 /* Convert - (~A) to A + 1. */
1257 /* Two's complement FP formats, such as c4x, may overflow. */
1267 {
1276 }
1298 {
1299 /* -(A + B) -> (-B) - A. */
1303 {
1307 }
1309 /* -(A + B) -> (-A) - B. */
1311 {
1315 }
1316 }
1320 /* - (A - B) -> B - A */
1332 /* Fall through. */
1336 {
1345 }
1353 /* In general we can't negate A / B, because if A is INT_MIN and
1354 B is 1, we may turn this into INT_MIN / -1 which is undefined
1355 and actually traps on some architectures. But if overflow is
1356 undefined, we can negate, because - (INT_MIN / 1) is an
1357 overflow. */
1359 {
1364 {
1371 }
1374 {
1381 }
1382 }
1386 /* Convert -((double)float) into (double)(-float). */
1388 {
1392 }
1396 /* Negate -f(x) as f(-x). */
1399 {
1405 }
1409 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1411 {
1416 {
1423 }
1424 }
1429 }
1432 }
1434 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1435 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1436 return NULL_TREE. */
1438 static tree
1440 {
1453 }
1454 \f
1455 /* Split a tree IN into a constant, literal and variable parts that could be
1456 combined with CODE to make IN. "constant" means an expression with
1457 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1458 commutative arithmetic operation. Store the constant part into *CONP,
1459 the literal in *LITP and return the variable part. If a part isn't
1460 present, set it to null. If the tree does not decompose in this way,
1461 return the entire tree as the variable part and the other parts as null.
1463 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1464 case, we negate an operand that was subtracted. Except if it is a
1465 literal for which we use *MINUS_LITP instead.
1467 If NEGATE_P is true, we are negating all of IN, again except a literal
1468 for which we use *MINUS_LITP instead.
1470 If IN is itself a literal or constant, return it as appropriate.
1472 Note that we do not guarantee that any of the three values will be the
1473 same type as IN, but they will have the same signedness and mode. */
1475 static tree
1478 {
1485 /* Strip any conversions that don't change the machine mode or signedness. */
1494 /* We can associate addition and subtraction together (even
1495 though the C standard doesn't say so) for integers because
1496 the value is not affected. For reals, the value might be
1497 affected, so we can't. */
1500 {
1506 /* First see if either of the operands is a literal, then a constant. */
1519 /* If we haven't dealt with either operand, this is not a case we can
1520 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1525 else
1528 /* Now do any needed negations. */
1535 }
1538 else
1542 {
1549 }
1552 }
1554 /* Re-associate trees split by the above function. T1 and T2 are either
1555 expressions to associate or null. Return the new expression, if any. If
1556 we build an operation, do it in TYPE and with CODE. */
1558 static tree
1560 {
1566 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1567 try to fold this since we will have infinite recursion. But do
1568 deal with any NEGATE_EXPRs. */
1571 {
1573 {
1582 }
1584 {
1587 }
1591 }
1595 }
1596 \f
1597 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1598 for use in int_const_binop, size_binop and size_diffop. */
1600 static bool
1602 {
1609 {
1618 }
1623 }
1626 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1627 to produce a new constant. Return NULL_TREE if we don't know how
1628 to evaluate CODE at compile-time.
1630 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1632 tree
1634 {
1638 HOST_WIDE_INT hi;
1640 HOST_WIDE_INT garbageh;
1641 tree t;
1644 int is_sizetype
1654 {
1670 /* It's unclear from the C standard whether shifts can overflow.
1671 The following code ignores overflow; perhaps a C standard
1672 interpretation ruling is needed. */
1701 /* This is a shortcut for a common special case. */
1706 {
1712 }
1714 /* ... fall through ... */
1720 {
1723 }
1726 {
1729 }
1736 /* This is a shortcut for a common special case. */
1741 {
1746 }
1748 /* ... fall through ... */
1766 else
1772 else
1778 }
1781 {
1784 /* Propagate overflow flags ourselves. */
1787 {
1790 }
1791 }
1792 else
1798 }
1800 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1801 constant. We assume ARG1 and ARG2 have the same data type, or at least
1802 are the same kind of constant and the same machine mode. Return zero if
1803 combining the constants is not allowed in the current operating mode.
1805 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1807 static tree
1809 {
1810 /* Sanity check for the recursive cases. */
1821 {
1823 REAL_VALUE_TYPE d1;
1824 REAL_VALUE_TYPE d2;
1825 REAL_VALUE_TYPE value;
1826 REAL_VALUE_TYPE result;
1830 /* The following codes are handled by real_arithmetic. */
1832 {
1843 }
1851 /* Don't perform operation if we honor signaling NaNs and
1852 either operand is a NaN. */
1857 /* Don't perform operation if it would raise a division
1858 by zero exception. */
1864 /* If either operand is a NaN, just return it. Otherwise, set up
1865 for floating-point trap; we return an overflow. */
1874 /* Don't constant fold this floating point operation if
1875 the result has overflowed and flag_trapping_math. */
1883 /* Don't constant fold this floating point operation if the
1884 result may dependent upon the run-time rounding mode and
1885 flag_rounding_math is set, or if GCC's software emulation
1886 is unable to accurately represent the result. */
1897 }
1900 {
1901 FIXED_VALUE_TYPE f1;
1902 FIXED_VALUE_TYPE f2;
1903 FIXED_VALUE_TYPE result;
1908 /* The following codes are handled by fixed_arithmetic. */
1910 {
1927 }
1934 /* Propagate overflow flags. */
1936 {
1939 }
1943 }
1946 {
1955 {
1966 notrunc);
1970 notrunc);
1974 {
1975 tree magsquared
1979 notrunc);
1980 tree t1
1984 notrunc);
1985 tree t2
1989 notrunc);
1996 }
2001 }
2005 }
2008 }
2010 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2011 indicates which particular sizetype to create. */
2013 tree
2015 {
2017 }
2018 \f
2019 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2020 is a tree code. The type of the result is taken from the operands.
2021 Both must be equivalent integer types, ala int_binop_types_match_p.
2022 If the operands are constant, so is the result. */
2024 tree
2026 {
2035 /* Handle the special case of two integer constants faster. */
2037 {
2038 /* And some specific cases even faster than that. */
2040 {
2045 }
2047 {
2050 }
2052 {
2055 }
2057 /* Handle general case of two integer constants. */
2059 }
2062 }
2064 /* Given two values, either both of sizetype or both of bitsizetype,
2065 compute the difference between the two values. Return the value
2066 in signed type corresponding to the type of the operands. */
2068 tree
2070 {
2072 tree ctype;
2077 /* If the type is already signed, just do the simple thing. */
2085 else
2088 /* If either operand is not a constant, do the conversions to the signed
2089 type and subtract. The hardware will do the right thing with any
2090 overflow in the subtraction. */
2095 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2096 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2097 overflow) and negate (which can't either). Special-case a result
2098 of zero while we're here. */
2103 else
2107 }
2108 \f
2109 /* A subroutine of fold_convert_const handling conversions of an
2110 INTEGER_CST to another integer type. */
2112 static tree
2114 {
2115 tree t;
2117 /* Given an integer constant, make new constant with new type,
2118 appropriately sign-extended or truncated. */
2121 /* Don't set the overflow when
2122 converting a pointer */
2130 }
2132 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2133 to an integer type. */
2135 static tree
2137 {
2139 tree t;
2141 /* The following code implements the floating point to integer
2142 conversion rules required by the Java Language Specification,
2143 that IEEE NaNs are mapped to zero and values that overflow
2144 the target precision saturate, i.e. values greater than
2145 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2146 are mapped to INT_MIN. These semantics are allowed by the
2147 C and C++ standards that simply state that the behavior of
2148 FP-to-integer conversion is unspecified upon overflow. */
2151 REAL_VALUE_TYPE r;
2155 {
2162 }
2164 /* If R is NaN, return zero and show we have an overflow. */
2166 {
2170 }
2172 /* See if R is less than the lower bound or greater than the
2173 upper bound. */
2176 {
2180 {
2184 }
2185 }
2188 {
2191 {
2194 {
2198 }
2199 }
2200 }
2208 }
2210 /* A subroutine of fold_convert_const handling conversions of a
2211 FIXED_CST to an integer type. */
2213 static tree
2215 {
2216 tree t;
2220 /* Right shift FIXED_CST to temp by fbit. */
2224 {
2229 /* Left shift temp to temp_trunc by fbit. */
2234 }
2235 else
2236 {
2241 }
2243 /* If FIXED_CST is negative, we need to round the value toward 0.
2244 By checking if the fractional bits are not zero to add 1 to temp. */
2247 {
2248 double_int one;
2252 }
2254 /* Given a fixed-point constant, make new constant with new type,
2255 appropriately sign-extended or truncated. */
2263 }
2265 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2266 to another floating point type. */
2268 static tree
2270 {
2271 REAL_VALUE_TYPE value;
2272 tree t;
2279 }
2281 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2282 to a floating point type. */
2284 static tree
2286 {
2287 REAL_VALUE_TYPE value;
2288 tree t;
2297 }
2299 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2300 to another fixed-point type. */
2302 static tree
2304 {
2305 FIXED_VALUE_TYPE value;
2306 tree t;
2313 /* Propagate overflow flags. */
2315 {
2318 }
2322 }
2324 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2325 to a fixed-point type. */
2327 static tree
2329 {
2330 FIXED_VALUE_TYPE value;
2331 tree t;
2340 /* Propagate overflow flags. */
2342 {
2345 }
2349 }
2351 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2352 to a fixed-point type. */
2354 static tree
2356 {
2357 FIXED_VALUE_TYPE value;
2358 tree t;
2366 /* Propagate overflow flags. */
2368 {
2371 }
2375 }
2377 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2378 type TYPE. If no simplification can be done return NULL_TREE. */
2380 static tree
2382 {
2387 {
2394 }
2396 {
2403 }
2405 {
2412 }
2414 }
2416 /* Construct a vector of zero elements of vector type TYPE. */
2418 static tree
2420 {
2431 }
2433 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2435 bool
2437 {
2452 {
2464 }
2465 }
2467 /* Convert expression ARG to type TYPE. Used by the middle-end for
2468 simple conversions in preference to calling the front-end's convert. */
2470 tree
2472 {
2474 tree tem;
2488 {
2493 {
2497 }
2502 {
2505 }
2512 {
2516 }
2518 {
2522 }
2524 {
2528 }
2531 {
2549 }
2554 {
2558 }
2561 {
2575 }
2579 {
2589 {
2593 {
2597 }
2605 }
2609 }
2627 }
2628 }
2629 \f
2630 /* Return false if expr can be assumed not to be an lvalue, true
2631 otherwise. */
2633 static bool
2635 {
2636 /* We only need to wrap lvalue tree codes. */
2638 {
2673 /* Assume the worst for front-end tree codes. */
2677 }
2680 }
2682 /* Return an expr equal to X but certainly not valid as an lvalue. */
2684 tree
2686 {
2687 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2688 us. */
2695 }
2697 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2698 Zero means allow extended lvalues. */
2702 /* When pedantic, return an expr equal to X but certainly not valid as a
2703 pedantic lvalue. Otherwise, return X. */
2705 static tree
2707 {
2710 else
2712 }
2713 \f
2714 /* Given a tree comparison code, return the code that is the logical inverse
2715 of the given code. It is not safe to do this for floating-point
2716 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2717 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2719 enum tree_code
2721 {
2726 {
2757 }
2758 }
2760 /* Similar, but return the comparison that results if the operands are
2761 swapped. This is safe for floating-point. */
2763 enum tree_code
2765 {
2767 {
2793 }
2794 }
2797 /* Convert a comparison tree code from an enum tree_code representation
2798 into a compcode bit-based encoding. This function is the inverse of
2799 compcode_to_comparison. */
2801 static enum comparison_code
2803 {
2805 {
2836 }
2837 }
2839 /* Convert a compcode bit-based encoding of a comparison operator back
2840 to GCC's enum tree_code representation. This function is the
2841 inverse of comparison_to_compcode. */
2843 static enum tree_code
2845 {
2847 {
2878 }
2879 }
2881 /* Return a tree for the comparison which is the combination of
2882 doing the AND or OR (depending on CODE) of the two operations LCODE
2883 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2884 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2885 if this makes the transformation invalid. */
2887 tree
2891 {
2898 {
2909 }
2912 {
2913 /* Eliminate unordered comparisons, as well as LTGT and ORD
2914 which are not used unless the mode has NaNs. */
2920 }
2922 {
2923 /* Check that the original operation and the optimized ones will trap
2924 under the same condition. */
2935 /* In a short-circuited boolean expression the LHS might be
2936 such that the RHS, if evaluated, will never trap. For
2937 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2938 if neither x nor y is NaN. (This is a mixed blessing: for
2939 example, the expression above will never trap, hence
2940 optimizing it to x < y would be invalid). */
2945 /* If the comparison was short-circuited, and only the RHS
2946 trapped, we may now generate a spurious trap. */
2951 /* If we changed the conditions that cause a trap, we lose. */
2954 }
2960 else
2963 }
2965 /* Return nonzero if CODE is a tree code that represents a truth value. */
2967 static int
2969 {
2974 }
2975 \f
2976 /* Return nonzero if two operands (typically of the same tree node)
2977 are necessarily equal. If either argument has side-effects this
2978 function returns zero. FLAGS modifies behavior as follows:
2980 If OEP_ONLY_CONST is set, only return nonzero for constants.
2981 This function tests whether the operands are indistinguishable;
2982 it does not test whether they are equal using C's == operation.
2983 The distinction is important for IEEE floating point, because
2984 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2985 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2987 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2988 even though it may hold multiple values during a function.
2989 This is because a GCC tree node guarantees that nothing else is
2990 executed between the evaluation of its "operands" (which may often
2991 be evaluated in arbitrary order). Hence if the operands themselves
2992 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2993 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2994 unset means assuming isochronic (or instantaneous) tree equivalence.
2995 Unless comparing arbitrary expression trees, such as from different
2996 statements, this flag can usually be left unset.
2998 If OEP_PURE_SAME is set, then pure functions with identical arguments
2999 are considered the same. It is used when the caller has other ways
3000 to ensure that global memory is unchanged in between. */
3002 int
3004 {
3005 /* If either is ERROR_MARK, they aren't equal. */
3009 /* If both types don't have the same signedness, then we can't consider
3010 them equal. We must check this before the STRIP_NOPS calls
3011 because they may change the signedness of the arguments. */
3015 /* If both types don't have the same precision, then it is not safe
3016 to strip NOPs. */
3023 /* In case both args are comparisons but with different comparison
3024 code, try to swap the comparison operands of one arg to produce
3025 a match and compare that variant. */
3029 {
3037 }
3040 /* This is needed for conversions and for COMPONENT_REF.
3041 Might as well play it safe and always test this. */
3047 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3048 We don't care about side effects in that case because the SAVE_EXPR
3049 takes care of that for us. In all other cases, two expressions are
3050 equal if they have no side effects. If we have two identical
3051 expressions with side effects that should be treated the same due
3052 to the only side effects being identical SAVE_EXPR's, that will
3053 be detected in the recursive calls below. */
3059 /* Next handle constant cases, those for which we can return 1 even
3060 if ONLY_CONST is set. */
3063 {
3078 {
3079 /* If we do not distinguish between signed and unsigned zero,
3080 consider them equal. */
3083 }
3087 {
3093 {
3095 flags))
3099 }
3102 }
3106 flags)
3108 flags));
3121 }
3126 /* Define macros to test an operand from arg0 and arg1 for equality and a
3127 variant that allows null and views null as being different from any
3128 non-null value. In the latter case, if either is null, the both
3129 must be; otherwise, do the normal comparison. */
3130 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3131 TREE_OPERAND (arg1, N), flags)
3133 #define OP_SAME_WITH_NULL(N) \
3134 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3135 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3138 {
3140 /* Two conversions are equal only if signedness and modes match. */
3142 {
3152 }
3162 /* For commutative ops, allow the other order. */
3170 /* If either of the pointer (or reference) expressions we are
3171 dereferencing contain a side effect, these cannot be equal. */
3177 {
3187 /* Operands 2 and 3 may be null.
3188 Compare the array index by value if it is constant first as we
3189 may have different types but same value here. */
3198 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3199 may be NULL when we're called to compare MEM_EXPRs. */
3209 }
3213 {
3228 /* Otherwise take into account this is a commutative operation. */
3236 }
3240 {
3242 /* If the CALL_EXPRs call different functions, then they
3243 clearly can not be equal. */
3245 flags))
3248 {
3252 else
3256 }
3258 /* Now see if all the arguments are the same. */
3259 {
3270 /* If we get here and both argument lists are exhausted
3271 then the CALL_EXPRs are equal. */
3273 }
3276 }
3279 /* Consider __builtin_sqrt equal to sqrt. */
3287 }
3289 #undef OP_SAME
3290 #undef OP_SAME_WITH_NULL
3291 }
3292 \f
3293 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3294 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3296 When in doubt, return 0. */
3298 static int
3300 {
3312 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3313 and see if the inner values are the same. This removes any
3314 signedness comparison, which doesn't matter here. */
3321 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3322 actual comparison operand, ARG0.
3324 First throw away any conversions to wider types
3325 already present in the operands. */
3334 {
3337 /* Make sure shorter operand is extended the right way
3338 to match the longer operand. */
3344 }
3347 }
3348 \f
3349 /* See if ARG is an expression that is either a comparison or is performing
3350 arithmetic on comparisons. The comparisons must only be comparing
3351 two different values, which will be stored in *CVAL1 and *CVAL2; if
3352 they are nonzero it means that some operands have already been found.
3353 No variables may be used anywhere else in the expression except in the
3354 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3355 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3357 If this is true, return 1. Otherwise, return zero. */
3359 static int
3361 {
3365 /* We can handle some of the tcc_expression cases here. */
3375 {
3376 /* If we've already found a CVAL1 or CVAL2, this expression is
3377 two complex to handle. */
3383 }
3386 {
3409 /* First see if we can handle the first operand, then the second. For
3410 the second operand, we know *CVAL1 can't be zero. It must be that
3411 one side of the comparison is each of the values; test for the
3412 case where this isn't true by failing if the two operands
3413 are the same. */
3422 ;
3426 ;
3427 else
3431 ;
3435 ;
3436 else
3443 }
3444 }
3445 \f
3446 /* ARG is a tree that is known to contain just arithmetic operations and
3447 comparisons. Evaluate the operations in the tree substituting NEW0 for
3448 any occurrence of OLD0 as an operand of a comparison and likewise for
3449 NEW1 and OLD1. */
3451 static tree
3453 {
3458 /* We can handle some of the tcc_expression cases here. */
3466 {
3481 {
3498 }
3499 /* Fall through - ??? */
3502 {
3506 /* We need to check both for exact equality and tree equality. The
3507 former will be true if the operand has a side-effect. In that
3508 case, we know the operand occurred exactly once. */
3521 }
3525 }
3526 }
3527 \f
3528 /* Return a tree for the case when the result of an expression is RESULT
3529 converted to TYPE and OMITTED was previously an operand of the expression
3530 but is now not needed (e.g., we folded OMITTED * 0).
3532 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3533 the conversion of RESULT to TYPE. */
3535 tree
3537 {
3540 /* If the resulting operand is an empty statement, just return the omitted
3541 statement casted to void. */
3549 }
3551 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3553 static tree
3555 {
3558 /* If the resulting operand is an empty statement, just return the omitted
3559 statement casted to void. */
3567 }
3569 /* Return a tree for the case when the result of an expression is RESULT
3570 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3571 of the expression but are now not needed.
3573 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3574 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3575 evaluated before OMITTED2. Otherwise, if neither has side effects,
3576 just do the conversion of RESULT to TYPE. */
3578 tree
3580 {
3589 }
3591 \f
3592 /* Return a simplified tree node for the truth-negation of ARG. This
3593 never alters ARG itself. We assume that ARG is an operation that
3594 returns a truth value (0 or 1).
3596 FIXME: one would think we would fold the result, but it causes
3597 problems with the dominator optimizer. */
3599 tree
3601 {
3605 /* If this is a comparison, we can simply invert it, except for
3606 floating-point non-equality comparisons, in which case we just
3607 enclose a TRUTH_NOT_EXPR around what we have. */
3610 {
3613 && flag_trapping_math
3617 else
3618 {
3623 else
3626 }
3627 }
3630 {
3645 /* Here we can invert either operand. We invert the first operand
3646 unless the second operand is a TRUTH_NOT_EXPR in which case our
3647 result is the XOR of the first operand with the inside of the
3648 negation of the second operand. */
3653 else
3672 {
3675 /* A COND_EXPR may have a throw as one operand, which
3676 then has void type. Just leave void operands
3677 as they are. */
3683 }
3716 }
3719 }
3721 /* Return a simplified tree node for the truth-negation of ARG. This
3722 never alters ARG itself. We assume that ARG is an operation that
3723 returns a truth value (0 or 1).
3725 FIXME: one would think we would fold the result, but it causes
3726 problems with the dominator optimizer. */
3728 tree
3730 {
3731 tree tem;
3741 }
3743 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3744 operands are another bit-wise operation with a common input. If so,
3745 distribute the bit operations to save an operation and possibly two if
3746 constants are involved. For example, convert
3747 (A | B) & (A | C) into A | (B & C)
3748 Further simplification will occur if B and C are constants.
3750 If this optimization cannot be done, 0 will be returned. */
3752 static tree
3754 {
3755 tree common;
3765 {
3769 }
3771 {
3775 }
3777 {
3781 }
3783 {
3787 }
3788 else
3793 }
3795 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3796 with code CODE. This optimization is unsafe. */
3797 static tree
3799 {
3803 /* (A / C) +- (B / C) -> (A +- B) / C. */
3813 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3818 {
3830 }
3833 }
3834 \f
3835 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3836 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3838 static tree
3841 {
3842 tree result;
3845 {
3852 }
3860 }
3862 /* Optimize a bit-field compare.
3864 There are two cases: First is a compare against a constant and the
3865 second is a comparison of two items where the fields are at the same
3866 bit position relative to the start of a chunk (byte, halfword, word)
3867 large enough to contain it. In these cases we can avoid the shift
3868 implicit in bitfield extractions.
3870 For constants, we emit a compare of the shifted constant with the
3871 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3872 compared. For two fields at the same position, we do the ANDs with the
3873 similar mask and compare the result of the ANDs.
3875 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3876 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3877 are the left and right operands of the comparison, respectively.
3879 If the optimization described above can be done, we return the resulting
3880 tree. Otherwise we return zero. */
3882 static tree
3885 {
3894 tree mask;
3895 tree offset;
3897 /* Get all the information about the extractions being done. If the bit size
3898 if the same as the size of the underlying object, we aren't doing an
3899 extraction at all and so can do nothing. We also don't want to
3900 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3901 then will no longer be able to replace it. */
3909 {
3910 /* If this is not a constant, we can only do something if bit positions,
3911 sizes, and signedness are the same. */
3919 }
3921 /* See if we can find a mode to refer to this field. We should be able to,
3922 but fail if we can't. */
3931 /* Set signed and unsigned types of the precision of this mode for the
3932 shifts below. */
3936 /* Compute the bit position and size for the new reference and our offset
3937 within it. If the new reference is the same size as the original, we
3938 won't optimize anything, so return zero. */
3948 /* Make the mask to be used against the extracted field. */
3955 /* If not comparing with constant, just rework the comparison
3956 and return. */
3960 unsigned_type,
3963 mask),
3966 unsigned_type,
3969 mask));
3971 /* Otherwise, we are handling the constant case. See if the constant is too
3972 big for the field. Warn and return a tree of for 0 (false) if so. We do
3973 this not only for its own sake, but to avoid having to test for this
3974 error case below. If we didn't, we might generate wrong code.
3976 For unsigned fields, the constant shifted right by the field length should
3977 be all zero. For signed fields, the high-order bits should agree with
3978 the sign bit. */
3981 {
3985 {
3989 }
3990 }
3991 else
3992 {
3996 {
4000 }
4001 }
4003 /* Single-bit compares should always be against zero. */
4005 {
4008 }
4010 /* Make a new bitfield reference, shift the constant over the
4011 appropriate number of bits and mask it with the computed mask
4012 (in case this was a signed field). If we changed it, make a new one. */
4015 {
4018 }
4028 rhs);
4029 }
4030 \f
4031 /* Subroutine for fold_truthop: decode a field reference.
4033 If EXP is a comparison reference, we return the innermost reference.
4035 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4036 set to the starting bit number.
4038 If the innermost field can be completely contained in a mode-sized
4039 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4041 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4042 otherwise it is not changed.
4044 *PUNSIGNEDP is set to the signedness of the field.
4046 *PMASK is set to the mask used. This is either contained in a
4047 BIT_AND_EXPR or derived from the width of the field.
4049 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4051 Return 0 if this is not a component reference or is one that we can't
4052 do anything with. */
4054 static tree
4059 {
4063 tree unsigned_type;
4066 /* All the optimizations using this function assume integer fields.
4067 There are problems with FP fields since the type_for_size call
4068 below can fail for, e.g., XFmode. */
4072 /* We are interested in the bare arrangement of bits, so strip everything
4073 that doesn't affect the machine mode. However, record the type of the
4074 outermost expression if it may matter below. */
4082 {
4088 }
4097 /* If the number of bits in the reference is the same as the bitsize of
4098 the outer type, then the outer type gives the signedness. Otherwise
4099 (in case of a small bitfield) the signedness is unchanged. */
4103 /* Compute the mask to access the bitfield. */
4112 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4120 }
4122 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4123 bit positions. */
4125 static int
4127 {
4130 tree tmask;
4134 return
4141 }
4143 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4144 represents the sign bit of EXP's type. If EXP represents a sign
4145 or zero extension, also test VAL against the unextended type.
4146 The return value is the (sub)expression whose sign bit is VAL,
4147 or NULL_TREE otherwise. */
4149 static tree
4151 {
4155 tree t;
4157 /* Tree EXP must have an integral type. */
4162 /* Tree VAL must be an integer constant. */
4169 {
4176 }
4177 else
4178 {
4185 }
4187 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4188 treat VAL as if it were unsigned. */
4193 /* Handle extension from a narrower type. */
4199 }
4201 /* Subroutine for fold_truthop: determine if an operand is simple enough
4202 to be evaluated unconditionally. */
4204 static int
4206 {
4207 /* Strip any conversions that don't change the machine mode. */
4216 /* Don't regard global variables as simple. They may be
4217 allocated in ways unknown to the compiler (shared memory,
4218 #pragma weak, etc). */
4221 /* Loading a static variable is unduly expensive, but global
4222 registers aren't expensive. */
4224 }
4225 \f
4226 /* The following functions are subroutines to fold_range_test and allow it to
4227 try to change a logical combination of comparisons into a range test.
4229 For example, both
4230 X == 2 || X == 3 || X == 4 || X == 5
4231 and
4232 X >= 2 && X <= 5
4233 are converted to
4234 (unsigned) (X - 2) <= 3
4236 We describe each set of comparisons as being either inside or outside
4237 a range, using a variable named like IN_P, and then describe the
4238 range with a lower and upper bound. If one of the bounds is omitted,
4239 it represents either the highest or lowest value of the type.
4241 In the comments below, we represent a range by two numbers in brackets
4242 preceded by a "+" to designate being inside that range, or a "-" to
4243 designate being outside that range, so the condition can be inverted by
4244 flipping the prefix. An omitted bound is represented by a "-". For
4245 example, "- [-, 10]" means being outside the range starting at the lowest
4246 possible value and ending at 10, in other words, being greater than 10.
4247 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4248 always false.
4250 We set up things so that the missing bounds are handled in a consistent
4251 manner so neither a missing bound nor "true" and "false" need to be
4252 handled using a special case. */
4254 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4255 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4256 and UPPER1_P are nonzero if the respective argument is an upper bound
4257 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4258 must be specified for a comparison. ARG1 will be converted to ARG0's
4259 type if both are specified. */
4261 static tree
4264 {
4265 tree tem;
4269 /* If neither arg represents infinity, do the normal operation.
4270 Else, if not a comparison, return infinity. Else handle the special
4271 comparison rules. Note that most of the cases below won't occur, but
4272 are handled for consistency. */
4275 {
4280 }
4285 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4286 for neither. In real maths, we cannot assume open ended ranges are
4287 the same. But, this is computer arithmetic, where numbers are finite.
4288 We can therefore make the transformation of any unbounded range with
4289 the value Z, Z being greater than any representable number. This permits
4290 us to treat unbounded ranges as equal. */
4294 {
4315 }
4318 }
4319 \f
4320 /* Given EXP, a logical expression, set the range it is testing into
4321 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4322 actually being tested. *PLOW and *PHIGH will be made of the same
4323 type as the returned expression. If EXP is not a comparison, we
4324 will most likely not be returning a useful value and range. Set
4325 *STRICT_OVERFLOW_P to true if the return value is only valid
4326 because signed overflow is undefined; otherwise, do not change
4327 *STRICT_OVERFLOW_P. */
4329 static tree
4332 {
4339 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4340 and see if we can refine the range. Some of the cases below may not
4341 happen, but it doesn't seem worth worrying about this. We "continue"
4342 the outer loop when we've changed something; otherwise we "break"
4343 the switch, which will "break" the while. */
4349 {
4354 {
4366 }
4369 {
4376 /* We can only do something if the range is testing for zero
4377 and if the second operand is an integer constant. Note that
4378 saying something is "in" the range we make is done by
4379 complementing IN_P since it will set in the initial case of
4380 being not equal to zero; "out" is leaving it alone. */
4387 {
4408 }
4410 /* If this is an unsigned comparison, we also know that EXP is
4411 greater than or equal to zero. We base the range tests we make
4412 on that fact, so we record it here so we can parse existing
4413 range tests. We test arg0_type since often the return type
4414 of, e.g. EQ_EXPR, is boolean. */
4416 {
4420 NULL_TREE))
4425 /* If the high bound is missing, but we have a nonzero low
4426 bound, reverse the range so it goes from zero to the low bound
4427 minus 1. */
4429 {
4434 }
4435 }
4441 /* (-x) IN [a,b] -> x in [-b, -a] */
4453 /* ~ X -> -X - 1 */
4462 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4463 move a constant to the other side. */
4468 /* If EXP is signed, any overflow in the computation is undefined,
4469 so we don't worry about it so long as our computations on
4470 the bounds don't overflow. For unsigned, overflow is defined
4471 and this is exactly the right thing. */
4483 /* Check for an unsigned range which has wrapped around the maximum
4484 value thus making n_high < n_low, and normalize it. */
4486 {
4492 /* If the range is of the form +/- [ x+1, x ], we won't
4493 be able to normalize it. But then, it represents the
4494 whole range or the empty set, so make it
4495 +/- [ -, - ]. */
4499 else
4501 }
4502 else
4526 /* If we're converting arg0 from an unsigned type, to exp,
4527 a signed type, we will be doing the comparison as unsigned.
4528 The tests above have already verified that LOW and HIGH
4529 are both positive.
4531 So we have to ensure that we will handle large unsigned
4532 values the same way that the current signed bounds treat
4533 negative values. */
4536 {
4537 tree high_positive;
4538 tree equiv_type;
4539 /* For fixed-point modes, we need to pass the saturating flag
4540 as the 2nd parameter. */
4545 else
4549 /* A range without an upper bound is, naturally, unbounded.
4550 Since convert would have cropped a very large value, use
4551 the max value for the destination type. */
4552 high_positive
4559 high_positive),
4562 /* If the low bound is specified, "and" the range with the
4563 range for which the original unsigned value will be
4564 positive. */
4566 {
4570 integer_zero_node),
4571 high_positive))
4575 }
4576 else
4577 {
4578 /* Otherwise, "or" the range with the range of the input
4579 that will be interpreted as negative. */
4583 integer_zero_node),
4584 high_positive))
4588 }
4589 }
4597 }
4600 }
4602 /* If EXP is a constant, we can evaluate whether this is true or false. */
4604 {
4611 }
4615 }
4616 \f
4617 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4618 type, TYPE, return an expression to test if EXP is in (or out of, depending
4619 on IN_P) the range. Return 0 if the test couldn't be created. */
4621 static tree
4623 {
4625 tree value;
4627 #ifdef HAVE_canonicalize_funcptr_for_compare
4628 /* Disable this optimization for function pointer expressions
4629 on targets that require function pointer canonicalization. */
4634 #endif
4637 {
4643 }
4661 {
4663 {
4667 }
4669 }
4671 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4673 {
4675 HOST_WIDE_INT hi;
4680 {
4683 }
4684 else
4685 {
4688 }
4691 {
4693 {
4696 }
4699 }
4700 }
4702 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4703 This requires wrap-around arithmetics for the type of the expression. */
4705 {
4707 /* There is no requirement that LOW be within the range of ETYPE
4708 if the latter is a subtype. It must, however, be within the base
4709 type of ETYPE. So be sure we do the subtraction in that type. */
4722 }
4724 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4727 {
4730 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4731 for the type in question, as we rely on this here. */
4741 else
4743 }
4753 {
4755 {
4761 }
4763 }
4771 }
4772 \f
4773 /* Return the predecessor of VAL in its type, handling the infinite case. */
4775 static tree
4777 {
4783 else
4785 }
4787 /* Return the successor of VAL in its type, handling the infinite case. */
4789 static tree
4791 {
4797 else
4799 }
4801 /* Given two ranges, see if we can merge them into one. Return 1 if we
4802 can, 0 if we can't. Set the output range into the specified parameters. */
4804 static int
4807 {
4811 tree tem;
4821 /* Make range 0 be the range that starts first, or ends last if they
4822 start at the same value. Swap them if it isn't. */
4825 || (lowequal
4828 {
4832 }
4834 /* Now flag two cases, whether the ranges are disjoint or whether the
4835 second range is totally subsumed in the first. Note that the tests
4836 below are simplified by the ones above. */
4842 /* We now have four cases, depending on whether we are including or
4843 excluding the two ranges. */
4845 {
4846 /* If they don't overlap, the result is false. If the second range
4847 is a subset it is the result. Otherwise, the range is from the start
4848 of the second to the end of the first. */
4853 else
4855 }
4858 {
4859 /* If they don't overlap, the result is the first range. If they are
4860 equal, the result is false. If the second range is a subset of the
4861 first, and the ranges begin at the same place, we go from just after
4862 the end of the second range to the end of the first. If the second
4863 range is not a subset of the first, or if it is a subset and both
4864 ranges end at the same place, the range starts at the start of the
4865 first range and ends just before the second range.
4866 Otherwise, we can't describe this as a single range. */
4872 {
4877 {
4878 /* We are in the weird situation where high0 > high1 but
4879 high1 has no successor. Punt. */
4881 }
4882 }
4884 {
4889 {
4890 /* low0 < low1 but low1 has no predecessor. Punt. */
4892 }
4893 }
4894 else
4896 }
4899 {
4900 /* If they don't overlap, the result is the second range. If the second
4901 is a subset of the first, the result is false. Otherwise,
4902 the range starts just after the first range and ends at the
4903 end of the second. */
4908 else
4909 {
4914 {
4915 /* high1 > high0 but high0 has no successor. Punt. */
4917 }
4918 }
4919 }
4921 else
4922 {
4923 /* The case where we are excluding both ranges. Here the complex case
4924 is if they don't overlap. In that case, the only time we have a
4925 range is if they are adjacent. If the second is a subset of the
4926 first, the result is the first. Otherwise, the range to exclude
4927 starts at the beginning of the first range and ends at the end of the
4928 second. */
4930 {
4935 else
4936 {
4937 /* Canonicalize - [min, x] into - [-, x]. */
4940 {
4945 /* FALLTHROUGH */
4958 }
4960 /* Canonicalize - [x, max] into - [x, -]. */
4963 {
4968 /* FALLTHROUGH */
4983 }
4985 /* The ranges might be also adjacent between the maximum and
4986 minimum values of the given type. For
4987 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4988 return + [x + 1, y - 1]. */
4990 {
4997 }
4998 else
5000 }
5001 }
5004 else
5006 }
5010 }
5011 \f
5013 /* Subroutine of fold, looking inside expressions of the form
5014 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5015 of the COND_EXPR. This function is being used also to optimize
5016 A op B ? C : A, by reversing the comparison first.
5018 Return a folded expression whose code is not a COND_EXPR
5019 anymore, or NULL_TREE if no folding opportunity is found. */
5021 static tree
5023 {
5028 tree tem;
5033 /* If we have A op 0 ? A : -A, consider applying the following
5034 transformations:
5036 A == 0? A : -A same as -A
5037 A != 0? A : -A same as A
5038 A >= 0? A : -A same as abs (A)
5039 A > 0? A : -A same as abs (A)
5040 A <= 0? A : -A same as -abs (A)
5041 A < 0? A : -A same as -abs (A)
5043 None of these transformations work for modes with signed
5044 zeros. If A is +/-0, the first two transformations will
5045 change the sign of the result (from +0 to -0, or vice
5046 versa). The last four will fix the sign of the result,
5047 even though the original expressions could be positive or
5048 negative, depending on the sign of A.
5050 Note that all these transformations are correct if A is
5051 NaN, since the two alternatives (A and -A) are also NaNs. */
5057 /* In the case that A is of the form X-Y, '-A' (arg2) may
5058 have already been folded to Y-X, check for that. */
5066 {
5078 /* Fall through. */
5100 }
5102 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5103 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5104 both transformations are correct when A is NaN: A != 0
5105 is then true, and A == 0 is false. */
5108 {
5113 }
5115 /* Try some transformations of A op B ? A : B.
5117 A == B? A : B same as B
5118 A != B? A : B same as A
5119 A >= B? A : B same as max (A, B)
5120 A > B? A : B same as max (B, A)
5121 A <= B? A : B same as min (A, B)
5122 A < B? A : B same as min (B, A)
5124 As above, these transformations don't work in the presence
5125 of signed zeros. For example, if A and B are zeros of
5126 opposite sign, the first two transformations will change
5127 the sign of the result. In the last four, the original
5128 expressions give different results for (A=+0, B=-0) and
5129 (A=-0, B=+0), but the transformed expressions do not.
5131 The first two transformations are correct if either A or B
5132 is a NaN. In the first transformation, the condition will
5133 be false, and B will indeed be chosen. In the case of the
5134 second transformation, the condition A != B will be true,
5135 and A will be chosen.
5137 The conversions to max() and min() are not correct if B is
5138 a number and A is not. The conditions in the original
5139 expressions will be false, so all four give B. The min()
5140 and max() versions would give a NaN instead. */
5142 /* Avoid these transformations if the COND_EXPR may be used
5143 as an lvalue in the C++ front-end. PR c++/19199. */
5144 && (in_gimple_form
5149 {
5154 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5156 {
5160 }
5163 {
5172 /* In C++ a ?: expression can be an lvalue, so put the
5173 operand which will be used if they are equal first
5174 so that we can convert this back to the
5175 corresponding COND_EXPR. */
5177 {
5184 }
5191 {
5198 }
5211 }
5212 }
5214 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5215 we might still be able to simplify this. For example,
5216 if C1 is one less or one more than C2, this might have started
5217 out as a MIN or MAX and been transformed by this function.
5218 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5224 {
5226 /* We can replace A with C1 in this case. */
5231 /* If C1 is C2 + 1, this is min(A, C2). */
5233 OEP_ONLY_CONST)
5237 OEP_ONLY_CONST))
5239 type,
5241 arg2));
5245 /* If C1 is C2 - 1, this is min(A, C2). */
5247 OEP_ONLY_CONST)
5251 OEP_ONLY_CONST))
5253 type,
5255 arg2));
5259 /* If C1 is C2 - 1, this is max(A, C2). */
5261 OEP_ONLY_CONST)
5265 OEP_ONLY_CONST))
5267 type,
5269 arg2));
5273 /* If C1 is C2 + 1, this is max(A, C2). */
5275 OEP_ONLY_CONST)
5279 OEP_ONLY_CONST))
5281 type,
5283 arg2));
5289 }
5292 }
5295 \f
5296 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5297 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
5298 #endif
5300 /* EXP is some logical combination of boolean tests. See if we can
5301 merge it into some range test. Return the new tree if so. */
5303 static tree
5305 {
5313 tree tem;
5317 /* If this is an OR operation, invert both sides; we will invert
5318 again at the end. */
5322 /* If both expressions are the same, if we can merge the ranges, and we
5323 can build the range test, return it or it inverted. If one of the
5324 ranges is always true or always false, consider it to be the same
5325 expression as the other. */
5333 {
5337 }
5339 /* On machines where the branch cost is expensive, if this is a
5340 short-circuited branch and the underlying object on both sides
5341 is the same, make a non-short-circuit operation. */
5347 {
5348 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5349 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5350 which cases we can't do this. */
5358 {
5367 {
5370 WARN_STRICT_OVERFLOW_COMPARISON);
5374 }
5375 }
5376 }
5379 }
5380 \f
5381 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5382 bit value. Arrange things so the extra bits will be set to zero if and
5383 only if C is signed-extended to its full width. If MASK is nonzero,
5384 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5386 static tree
5388 {
5391 tree temp;
5396 /* We work by getting just the sign bit into the low-order bit, then
5397 into the high-order bit, then sign-extend. We then XOR that value
5398 with C. */
5402 /* We must use a signed type in order to get an arithmetic right shift.
5403 However, we must also avoid introducing accidental overflows, so that
5404 a subsequent call to integer_zerop will work. Hence we must
5405 do the type conversion here. At this point, the constant is either
5406 zero or one, and the conversion to a signed type can never overflow.
5407 We could get an overflow if this conversion is done anywhere else. */
5416 /* If necessary, convert the type back to match the type of C. */
5421 }
5422 \f
5423 /* Find ways of folding logical expressions of LHS and RHS:
5424 Try to merge two comparisons to the same innermost item.
5425 Look for range tests like "ch >= '0' && ch <= '9'".
5426 Look for combinations of simple terms on machines with expensive branches
5427 and evaluate the RHS unconditionally.
5429 For example, if we have p->a == 2 && p->b == 4 and we can make an
5430 object large enough to span both A and B, we can do this with a comparison
5431 against the object ANDed with the a mask.
5433 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5434 operations to do this with one comparison.
5436 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5437 function and the one above.
5439 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5440 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5442 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5443 two operands.
5445 We return the simplified tree or 0 if no optimization is possible. */
5447 static tree
5449 {
5450 /* If this is the "or" of two comparisons, we can do something if
5451 the comparisons are NE_EXPR. If this is the "and", we can do something
5452 if the comparisons are EQ_EXPR. I.e.,
5453 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5455 WANTED_CODE is this operation code. For single bit fields, we can
5456 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5457 comparison for one-bit fields. */
5479 /* Start by getting the comparison codes. Fail if anything is volatile.
5480 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5481 it were surrounded with a NE_EXPR. */
5490 {
5494 }
5497 {
5501 }
5512 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5515 {
5516 tree result;
5519 {
5524 }
5527 {
5533 }
5534 }
5539 /* If the RHS can be evaluated unconditionally and its operands are
5540 simple, it wins to evaluate the RHS unconditionally on machines
5541 with expensive branches. In this case, this isn't a comparison
5542 that can be merged. Avoid doing this if the RHS is a floating-point
5543 comparison since those can trap. */
5549 {
5550 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5560 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5571 {
5575 }
5576 }
5578 /* See if the comparisons can be merged. Then get all the parameters for
5579 each side. */
5603 /* It must be true that the inner operation on the lhs of each
5604 comparison must be the same if we are to be able to do anything.
5605 Then see if we have constants. If not, the same must be true for
5606 the rhs's. */
5617 else
5620 /* If either comparison code is not correct for our logical operation,
5621 fail. However, we can convert a one-bit comparison against zero into
5622 the opposite comparison against that bit being set in the field. */
5626 {
5628 {
5629 /* Make the left operand unsigned, since we are only interested
5630 in the value of one bit. Otherwise we are doing the wrong
5631 thing below. */
5634 }
5635 else
5637 }
5639 /* This is analogous to the code for l_const above. */
5641 {
5643 {
5646 }
5647 else
5649 }
5651 /* See if we can find a mode that contains both fields being compared on
5652 the left. If we can't, fail. Otherwise, update all constants and masks
5653 to be relative to a field of that size. */
5658 volatilep);
5668 {
5671 }
5679 {
5687 {
5691 }
5692 }
5694 {
5702 {
5706 }
5707 }
5709 /* If the right sides are not constant, do the same for it. Also,
5710 disallow this optimization if a size or signedness mismatch occurs
5711 between the left and right sides. */
5713 {
5716 /* Make sure the two fields on the right
5717 correspond to the left without being swapped. */
5725 volatilep);
5735 {
5738 }
5745 /* Make a mask that corresponds to both fields being compared.
5746 Do this for both items being compared. If the operands are the
5747 same size and the bits being compared are in the same position
5748 then we can do this by masking both and comparing the masked
5749 results. */
5753 {
5765 }
5767 /* There is still another way we can do something: If both pairs of
5768 fields being compared are adjacent, we may be able to make a wider
5769 field containing them both.
5771 Note that we still must mask the lhs/rhs expressions. Furthermore,
5772 the mask must be shifted to account for the shift done by
5773 make_bit_field_ref. */
5778 {
5779 tree type;
5791 /* Convert to the smaller type before masking out unwanted bits. */
5794 {
5796 {
5800 }
5802 {
5806 }
5807 }
5816 }
5819 }
5821 /* Handle the case of comparisons with constants. If there is something in
5822 common between the masks, those bits of the constants must be the same.
5823 If not, the condition is always false. Test for this to avoid generating
5824 incorrect code below. */
5829 {
5831 {
5834 }
5835 else
5836 {
5839 }
5840 }
5842 /* Construct the expression we will return. First get the component
5843 reference we will make. Unless the mask is all ones the width of
5844 that field, perform the mask operation. Then compare with the
5845 merged constant. */
5855 }
5856 \f
5857 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5858 constant. */
5860 static tree
5862 {
5866 tree minmax_const;
5868 tree inner;
5878 /* If something does not permit us to optimize, return the original tree. */
5886 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5887 and GT_EXPR, doing the rest with recursive calls using logical
5888 simplifications. */
5890 {
5892 {
5898 }
5901 return
5903 optimize_minmax_comparison
5905 optimize_minmax_comparison
5910 /* MAX (X, 0) == 0 -> X <= 0 */
5914 /* MAX (X, 0) == 5 -> X == 5 */
5918 /* MAX (X, 0) == -1 -> false */
5922 /* MIN (X, 0) == 0 -> X >= 0 */
5926 /* MIN (X, 0) == 5 -> false */
5929 else
5930 /* MIN (X, 0) == -1 -> X == -1 */
5935 /* MAX (X, 0) > 0 -> X > 0
5936 MAX (X, 0) > 5 -> X > 5 */
5940 /* MAX (X, 0) > -1 -> true */
5944 /* MIN (X, 0) > 0 -> false
5945 MIN (X, 0) > 5 -> false */
5948 else
5949 /* MIN (X, 0) > -1 -> X > -1 */
5954 }
5955 }
5956 \f
5957 /* T is an integer expression that is being multiplied, divided, or taken a
5958 modulus (CODE says which and what kind of divide or modulus) by a
5959 constant C. See if we can eliminate that operation by folding it with
5960 other operations already in T. WIDE_TYPE, if non-null, is a type that
5961 should be used for the computation if wider than our type.
5963 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5964 (X * 2) + (Y * 4). We must, however, be assured that either the original
5965 expression would not overflow or that overflow is undefined for the type
5966 in the language in question.
5968 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5969 the machine has a multiply-accumulate insn or that this is part of an
5970 addressing calculation.
5972 If we return a non-null expression, it is an equivalent form of the
5973 original computation, but need not be in the original type.
5975 We set *STRICT_OVERFLOW_P to true if the return values depends on
5976 signed overflow being undefined. Otherwise we do not change
5977 *STRICT_OVERFLOW_P. */
5979 static tree
5982 {
5983 /* To avoid exponential search depth, refuse to allow recursion past
5984 three levels. Beyond that (1) it's highly unlikely that we'll find
5985 something interesting and (2) we've probably processed it before
5986 when we built the inner expression. */
5989 tree ret;
5994 depth++;
5996 depth--;
5999 }
6001 static tree
6004 {
6015 /* Don't deal with constants of zero here; they confuse the code below. */
6025 /* Note that we need not handle conditional operations here since fold
6026 already handles those cases. So just do arithmetic here. */
6028 {
6030 /* For a constant, we can always simplify if we are a multiply
6031 or (for divide and modulus) if it is a multiple of our constant. */
6039 /* If op0 is an expression ... */
6045 /* ... and is unsigned, and its type is smaller than ctype,
6046 then we cannot pass through as widening. */
6052 /* ... or this is a truncation (t is narrower than op0),
6053 then we cannot pass through this narrowing. */
6056 /* ... or signedness changes for division or modulus,
6057 then we cannot pass through this conversion. */
6063 /* Pass the constant down and see if we can make a simplification. If
6064 we can, replace this expression with the inner simplification for
6065 possible later conversion to our or some other type. */
6070 code == MULT_EXPR
6072 strict_overflow_p))))
6077 /* If widening the type changes it from signed to unsigned, then we
6078 must avoid building ABS_EXPR itself as unsigned. */
6080 {
6084 {
6087 }
6089 }
6090 /* FALLTHROUGH */
6098 /* If widening the type changes the signedness, then we can't perform
6099 this optimization as that changes the result. */
6103 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6109 {
6116 }
6120 /* If the second operand is constant, this is a multiplication
6121 or floor division, by a power of two, so we can treat it that
6122 way unless the multiplier or divisor overflows. Signed
6123 left-shift overflow is implementation-defined rather than
6124 undefined in C90, so do not convert signed left shift into
6125 multiplication. */
6128 /* const_binop may not detect overflow correctly,
6129 so check for it explicitly here. */
6134 size_one_node,
6144 /* See if we can eliminate the operation on both sides. If we can, we
6145 can return a new PLUS or MINUS. If we can't, the only remaining
6146 cases where we can do anything are if the second operand is a
6147 constant. */
6153 /* If not multiplication, we can only do this if both operands
6154 are divisible by c. */
6157 {
6162 }
6164 /* If this was a subtraction, negate OP1 and set it to be an addition.
6165 This simplifies the logic below. */
6172 /* If either OP1 or C are negative, this optimization is not safe for
6173 some of the division and remainder types while for others we need
6174 to change the code. */
6176 {
6184 }
6186 /* If it's a multiply or a division/modulus operation of a multiple
6187 of our constant, do the operation and verify it doesn't overflow. */
6190 {
6193 /* We allow the constant to overflow with wrapping semantics. */
6197 }
6198 else
6201 /* If we have an unsigned type is not a sizetype, we cannot widen
6202 the operation since it will change the result if the original
6203 computation overflowed. */
6209 /* If we were able to eliminate our operation from the first side,
6210 apply our operation to the second side and reform the PLUS. */
6214 /* The last case is if we are a multiply. In that case, we can
6215 apply the distributive law to commute the multiply and addition
6216 if the multiplication of the constants doesn't overflow. */
6222 op1);
6227 /* We have a special case here if we are doing something like
6228 (C * 8) % 4 since we know that's zero. */
6235 /* ... fall through ... */
6239 /* If we can extract our operation from the LHS, do so and return a
6240 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6241 do something only if the second operand is a constant. */
6255 /* If these are the same operation types, we can associate them
6256 assuming no overflow. */
6263 /* If these operations "cancel" each other, we have the main
6264 optimizations of this pass, which occur when either constant is a
6265 multiple of the other, in which case we replace this with either an
6266 operation or CODE or TCODE.
6268 If we have an unsigned type that is not a sizetype, we cannot do
6269 this since it will change the result if the original computation
6270 overflowed. */
6278 {
6280 {
6287 }
6289 {
6296 }
6297 }
6302 }
6305 }
6306 \f
6307 /* Return a node which has the indicated constant VALUE (either 0 or
6308 1), and is of the indicated TYPE. */
6310 tree
6312 {
6317 else
6319 }
6322 /* Return true if expr looks like an ARRAY_REF and set base and
6323 offset to the appropriate trees. If there is no offset,
6324 offset is set to NULL_TREE. Base will be canonicalized to
6325 something you can get the element type from using
6326 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
6327 in bytes to the base in sizetype. */
6329 static bool
6331 {
6332 /* One canonical form is a PLUS_EXPR with the first
6333 argument being an ADDR_EXPR with a possible NOP_EXPR
6334 attached. */
6336 {
6339 /* Strip NOP_EXPRs here because the C frontends and/or
6340 folders present us (int *)&x.a p+ 4 possibly. */
6343 {
6350 }
6351 }
6352 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
6353 which we transform into an ADDR_EXPR with appropriate
6354 offset. For other arguments to the ADDR_EXPR we assume
6355 zero offset and as such do not care about the ADDR_EXPR
6356 type and strip possible nops from it. */
6358 {
6361 {
6367 }
6368 else
6369 {
6370 /* Handle array-to-pointer decay as &a. */
6373 else
6376 }
6378 }
6379 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
6382 {
6386 }
6389 }
6392 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6393 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6394 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6395 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6396 COND is the first argument to CODE; otherwise (as in the example
6397 given here), it is the second argument. TYPE is the type of the
6398 original expression. Return NULL_TREE if no simplification is
6399 possible. */
6401 static tree
6405 {
6412 /* This transformation is only worthwhile if we don't have to wrap
6413 arg in a SAVE_EXPR, and the operation can be simplified on at least
6414 one of the branches once its pushed inside the COND_EXPR. */
6419 {
6423 /* If this operand throws an expression, then it does not make
6424 sense to try to perform a logical or arithmetic operation
6425 involving it. */
6430 }
6431 else
6432 {
6437 }
6441 {
6445 else
6447 }
6449 {
6453 else
6455 }
6459 }
6461 \f
6462 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6464 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6465 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6466 ADDEND is the same as X.
6468 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6469 and finite. The problematic cases are when X is zero, and its mode
6470 has signed zeros. In the case of rounding towards -infinity,
6471 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6472 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6474 static bool
6476 {
6480 /* Don't allow the fold with -fsignaling-nans. */
6484 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6488 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6493 /* The mode has signed zeros, and we have to honor their sign.
6494 In this situation, there is only one case we can return true for.
6495 X - 0 is the same as X unless rounding towards -infinity is
6496 supported. */
6498 }
6500 /* Subroutine of fold() that checks comparisons of built-in math
6501 functions against real constants.
6503 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6504 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6505 is the type of the result and ARG0 and ARG1 are the operands of the
6506 comparison. ARG1 must be a TREE_REAL_CST.
6508 The function returns the constant folded tree if a simplification
6509 can be made, and NULL_TREE otherwise. */
6511 static tree
6514 {
6515 REAL_VALUE_TYPE c;
6518 {
6524 {
6525 /* sqrt(x) < y is always false, if y is negative. */
6529 /* sqrt(x) > y is always true, if y is negative and we
6530 don't care about NaNs, i.e. negative values of x. */
6534 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6537 }
6539 {
6540 REAL_VALUE_TYPE c2;
6546 {
6547 /* sqrt(x) > y is x == +Inf, when y is very large. */
6552 /* sqrt(x) > y is always false, when y is very large
6553 and we don't care about infinities. */
6555 }
6557 /* sqrt(x) > c is the same as x > c*c. */
6560 }
6562 {
6563 REAL_VALUE_TYPE c2;
6569 {
6570 /* sqrt(x) < y is always true, when y is a very large
6571 value and we don't care about NaNs or Infinities. */
6575 /* sqrt(x) < y is x != +Inf when y is very large and we
6576 don't care about NaNs. */
6581 /* sqrt(x) < y is x >= 0 when y is very large and we
6582 don't care about Infinities. */
6587 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6596 dconst0)),
6599 c2)));
6600 }
6602 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6607 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6610 {
6615 dconst0)),
6618 c2)));
6619 }
6620 }
6621 }
6624 }
6626 /* Subroutine of fold() that optimizes comparisons against Infinities,
6627 either +Inf or -Inf.
6629 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6630 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6631 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6633 The function returns the constant folded tree if a simplification
6634 can be made, and NULL_TREE otherwise. */
6636 static tree
6638 {
6640 REAL_VALUE_TYPE max;
6641 tree temp;
6646 /* For negative infinity swap the sense of the comparison. */
6652 {
6654 /* x > +Inf is always false, if with ignore sNANs. */
6660 /* x <= +Inf is always true, if we don't case about NaNs. */
6664 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6667 {
6670 }
6675 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6681 /* x < +Inf is always equal to x <= DBL_MAX. */
6687 /* x != +Inf is always equal to !(x > DBL_MAX). */
6699 }
6702 }
6704 /* Subroutine of fold() that optimizes comparisons of a division by
6705 a nonzero integer constant against an integer constant, i.e.
6706 X/C1 op C2.
6708 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6709 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6710 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6712 The function returns the constant folded tree if a simplification
6713 can be made, and NULL_TREE otherwise. */
6715 static tree
6717 {
6722 HOST_WIDE_INT hpart;
6727 /* We have to do this the hard way to detect unsigned overflow.
6728 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6739 {
6744 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6752 }
6754 {
6758 {
6777 }
6778 }
6779 else
6780 {
6781 /* A negative divisor reverses the relational operators. */
6787 {
6806 }
6807 }
6810 {
6831 {
6834 }
6839 {
6842 }
6847 {
6850 }
6855 {
6858 }
6863 }
6866 }
6869 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6870 equality/inequality test, then return a simplified form of the test
6871 using a sign testing. Otherwise return NULL. TYPE is the desired
6872 result type. */
6874 static tree
6876 tree result_type)
6877 {
6878 /* If this is testing a single bit, we can optimize the test. */
6882 {
6883 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6884 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6888 /* This is only a win if casting to a signed type is cheap,
6889 i.e. when arg00's type is not a partial mode. */
6892 {
6897 }
6898 }
6901 }
6903 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6904 equality/inequality test, then return a simplified form of
6905 the test using shifts and logical operations. Otherwise return
6906 NULL. TYPE is the desired result type. */
6908 tree
6910 tree result_type)
6911 {
6912 /* If this is testing a single bit, we can optimize the test. */
6916 {
6925 /* First, see if we can fold the single bit test into a sign-bit
6926 test. */
6928 result_type);
6932 /* Otherwise we have (A & C) != 0 where C is a single bit,
6933 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6934 Similarly for (A & C) == 0. */
6936 /* If INNER is a right shift of a constant and it plus BITNUM does
6937 not overflow, adjust BITNUM and INNER. */
6944 {
6947 }
6949 /* If we are going to be able to omit the AND below, we must do our
6950 operations as unsigned. If we must use the AND, we have a choice.
6951 Normally unsigned is faster, but for some machines signed is. */
6952 #ifdef LOAD_EXTEND_OP
6955 #else
6957 #endif
6973 /* Put the AND last so it can combine with more things. */
6976 /* Make sure to return the proper type. */
6980 }
6982 }
6984 /* Check whether we are allowed to reorder operands arg0 and arg1,
6985 such that the evaluation of arg1 occurs before arg0. */
6987 static bool
6989 {
6996 }
6998 /* Test whether it is preferable two swap two operands, ARG0 and
6999 ARG1, for example because ARG0 is an integer constant and ARG1
7000 isn't. If REORDER is true, only recommend swapping if we can
7001 evaluate the operands in reverse order. */
7003 bool
7005 {
7041 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7042 for commutative and comparison operators. Ensuring a canonical
7043 form allows the optimizers to find additional redundancies without
7044 having to explicitly check for both orderings. */
7050 /* Put SSA_NAMEs last. */
7056 /* Put variables last. */
7063 }
7065 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7066 ARG0 is extended to a wider type. */
7068 static tree
7070 {
7072 tree arg1_unw;
7081 #ifdef HAVE_canonicalize_funcptr_for_compare
7082 /* Disable this optimization if we're casting a function pointer
7083 type on targets that require function pointer canonicalization. */
7088 #endif
7095 /* If possible, express the comparison in the shorter mode. */
7111 /* If we are comparing with the integer that does not fit into the range
7112 of the shorter type, the result is known. */
7123 {
7150 }
7153 }
7155 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7156 ARG0 just the signedness is changed. */
7158 static tree
7161 {
7162 tree arg0_inner;
7173 #ifdef HAVE_canonicalize_funcptr_for_compare
7174 /* Disable this optimization if we're casting a function pointer
7175 type on targets that require function pointer canonicalization. */
7180 #endif
7200 else
7204 }
7206 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7207 step of the array. Reconstructs s and delta in the case of s * delta
7208 being an integer constant (and thus already folded).
7209 ADDR is the address. MULT is the multiplicative expression.
7210 If the function succeeds, the new address expression is returned. Otherwise
7211 NULL_TREE is returned. */
7213 static tree
7215 {
7219 tree itype;
7222 /* Strip the nops that might be added when converting op1 to sizetype. */
7225 /* Canonicalize op1 into a possibly non-constant delta
7226 and an INTEGER_CST s. */
7228 {
7235 {
7238 }
7240 {
7243 }
7244 else
7246 }
7248 {
7251 }
7252 else
7253 {
7254 /* Simulate we are delta * 1. */
7257 }
7260 {
7262 {
7263 /* Remember if this was a multi-dimensional array. */
7276 {
7279 }
7280 else
7281 {
7282 /* Try if delta is a multiple of step. */
7287 }
7289 /* Only fold here if we can verify we do not overflow one
7290 dimension of a multi-dimensional array. */
7292 {
7293 tree tmp;
7309 }
7312 }
7313 else
7318 }
7320 /* We found the suitable array reference. So copy everything up to it,
7321 and replace the index. */
7328 {
7332 }
7340 }
7343 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7344 means A >= Y && A != MAX, but in this case we know that
7345 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7347 static tree
7349 {
7356 else
7365 {
7368 }
7370 {
7373 }
7374 else
7381 {
7382 /* Convert the pointer types into integer before taking the difference. */
7386 }
7387 else
7394 }
7396 /* Fold a sum or difference of at least one multiplication.
7397 Returns the folded tree or NULL if no simplification could be made. */
7399 static tree
7401 {
7405 /* (A * C) +- (B * C) -> (A+-B) * C.
7406 (A * C) +- A -> A * (C+-1).
7407 We are most concerned about the case where C is a constant,
7408 but other combinations show up during loop reduction. Since
7409 it is not difficult, try all four possibilities. */
7412 {
7415 }
7417 {
7420 }
7421 else
7422 {
7423 /* We cannot generate constant 1 for fract. */
7428 }
7430 {
7433 }
7435 {
7438 }
7439 else
7440 {
7441 /* We cannot generate constant 1 for fract. */
7446 }
7458 /* No identical multiplicands; see if we can find a common
7459 power-of-two factor in non-power-of-two multiplies. This
7460 can help in multi-dimensional array access. */
7463 {
7466 tree maybe_same;
7470 /* Move min of absolute values to int11. */
7473 {
7478 }
7479 else
7483 {
7491 }
7492 }
7502 }
7504 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7505 specified by EXPR into the buffer PTR of length LEN bytes.
7506 Return the number of bytes placed in the buffer, or zero
7507 upon failure. */
7509 static int
7511 {
7522 {
7526 else
7531 {
7538 else
7540 }
7541 else
7544 }
7546 }
7549 /* Subroutine of native_encode_expr. Encode the REAL_CST
7550 specified by EXPR into the buffer PTR of length LEN bytes.
7551 Return the number of bytes placed in the buffer, or zero
7552 upon failure. */
7554 static int
7556 {
7562 /* There are always 32 bits in each long, no matter the size of
7563 the hosts long. We handle floating point representations with
7564 up to 192 bits. */
7575 {
7580 {
7587 else
7589 }
7590 else
7593 }
7595 }
7597 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7598 specified by EXPR into the buffer PTR of length LEN bytes.
7599 Return the number of bytes placed in the buffer, or zero
7600 upon failure. */
7602 static int
7604 {
7606 tree part;
7617 }
7620 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7621 specified by EXPR into the buffer PTR of length LEN bytes.
7622 Return the number of bytes placed in the buffer, or zero
7623 upon failure. */
7625 static int
7627 {
7637 {
7639 {
7642 }
7643 else
7647 {
7650 }
7651 else
7652 {
7656 }
7658 }
7660 }
7663 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7664 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7665 buffer PTR of length LEN bytes. Return the number of bytes
7666 placed in the buffer, or zero upon failure. */
7668 int
7670 {
7672 {
7687 }
7688 }
7691 /* Subroutine of native_interpret_expr. Interpret the contents of
7692 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7693 If the buffer cannot be interpreted, return NULL_TREE. */
7695 static tree
7697 {
7711 {
7714 {
7721 else
7723 }
7724 else
7730 else
7733 }
7736 }
7739 /* Subroutine of native_interpret_expr. Interpret the contents of
7740 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7741 If the buffer cannot be interpreted, return NULL_TREE. */
7743 static tree
7745 {
7750 /* There are always 32 bits in each long, no matter the size of
7751 the hosts long. We handle floating point representations with
7752 up to 192 bits. */
7753 REAL_VALUE_TYPE r;
7764 {
7767 {
7774 else
7776 }
7777 else
7782 }
7786 }
7789 /* Subroutine of native_interpret_expr. Interpret the contents of
7790 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7791 If the buffer cannot be interpreted, return NULL_TREE. */
7793 static tree
7795 {
7810 }
7813 /* Subroutine of native_interpret_expr. Interpret the contents of
7814 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7815 If the buffer cannot be interpreted, return NULL_TREE. */
7817 static tree
7819 {
7831 {
7836 }
7838 }
7841 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7842 the buffer PTR of length LEN as a constant of type TYPE. For
7843 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7844 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7845 return NULL_TREE. */
7847 tree
7849 {
7851 {
7868 }
7869 }
7872 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7873 TYPE at compile-time. If we're unable to perform the conversion
7874 return NULL_TREE. */
7876 static tree
7878 {
7879 /* We support up to 512-bit values (for V8DFmode). */
7883 /* Check that the host and target are sane. */
7892 }
7894 /* Build an expression for the address of T. Folds away INDIRECT_REF
7895 to avoid confusing the gimplify process. When IN_FOLD is true
7896 avoid modifications of T. */
7898 static tree
7900 {
7901 /* The size of the object is not relevant when talking about its address. */
7905 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7908 {
7913 }
7915 {
7925 }
7926 else
7930 }
7932 /* Build an expression for the address of T with type PTRTYPE. This
7933 function modifies the input parameter 'T' by sometimes setting the
7934 TREE_ADDRESSABLE flag. */
7936 tree
7938 {
7940 }
7942 /* Build an expression for the address of T. This function modifies
7943 the input parameter 'T' by sometimes setting the TREE_ADDRESSABLE
7944 flag. When called from fold functions, use fold_addr_expr instead. */
7946 tree
7948 {
7952 }
7954 /* Same as build_fold_addr_expr, builds an expression for the address
7955 of T, but avoids touching the input node 't'. Fold functions
7956 should use this version. */
7958 static tree
7960 {
7964 }
7966 /* Fold a unary expression of code CODE and type TYPE with operand
7967 OP0. Return the folded expression if folding is successful.
7968 Otherwise, return NULL_TREE. */
7970 tree
7972 {
7973 tree tem;
7974 tree arg0;
7982 {
7985 {
7986 /* Don't use STRIP_NOPS, because signedness of argument type
7987 matters. */
7989 }
7990 else
7991 {
7992 /* Strip any conversions that don't change the mode. This
7993 is safe for every expression, except for a comparison
7994 expression because its signedness is derived from its
7995 operands.
7997 Note that this is done as an internal manipulation within
7998 the constant folder, in order to find the simplest
7999 representation of the arguments so that their form can be
8000 studied. In any cases, the appropriate type conversions
8001 should be put back in the tree that will get out of the
8002 constant folder. */
8004 }
8005 }
8008 {
8013 {
8023 /* If this was a conversion, and all we did was to move into
8024 inside the COND_EXPR, bring it back out. But leave it if
8025 it is a conversion from integer to integer and the
8026 result precision is no wider than a word since such a
8027 conversion is cheap and may be optimized away by combine,
8028 while it couldn't if it were outside the COND_EXPR. Then return
8029 so we don't get into an infinite recursion loop taking the
8030 conversion out and then back in. */
8042 && (INTEGRAL_TYPE_P
8054 }
8056 {
8058 {
8062 }
8066 integer_one_node),
8068 integer_zero_node));
8069 }
8070 }
8073 {
8081 /* If we have (type) (a CMP b) and type is an integral type, return
8082 new expression involving the new type. */
8087 /* Handle cases of two conversions in a row. */
8090 {
8112 /* In addition to the cases of two conversions in a row
8113 handled below, if we are converting something to its own
8114 type via an object of identical or wider precision, neither
8115 conversion is needed. */
8122 /* Likewise, if the intermediate and final types are either both
8123 float or both integer, we don't need the middle conversion if
8124 it is wider than the final type and doesn't change the signedness
8125 (for integers). Avoid this if the final type is a pointer
8126 since then we sometimes need the inner conversion. Likewise if
8127 the outer has a precision not equal to the size of its mode. */
8136 && ! final_ptr
8140 /* If we have a sign-extension of a zero-extended value, we can
8141 replace that by a single zero-extension. */
8147 /* Two conversions in a row are not needed unless:
8148 - some conversion is floating-point (overstrict for now), or
8149 - some conversion is a vector (overstrict for now), or
8150 - the intermediate type is narrower than both initial and
8151 final, or
8152 - the intermediate type and innermost type differ in signedness,
8153 and the outermost type is wider than the intermediate, or
8154 - the initial type is a pointer type and the precisions of the
8155 intermediate and final types differ, or
8156 - the final type is a pointer type and the precisions of the
8157 initial and intermediate types differ.
8158 - the final type is a pointer type and the initial type not
8159 - the initial type is a pointer to an array and the final type
8160 not. */
8174 && ! (inside_ptr
8178 }
8180 /* Handle (T *)&A.B.C for A being of type T and B and C
8181 living at offset zero. This occurs frequently in
8182 C++ upcasting and then accessing the base. */
8186 {
8188 tree offset;
8194 /* If the reference was to a (constant) zero offset, we can use
8195 the address of the base if it has the same base type
8196 as the result type. */
8201 }
8206 /* Detect assigning a bitfield. */
8208 && DECL_BIT_FIELD
8210 {
8211 /* Don't leave an assignment inside a conversion
8212 unless assigning a bitfield. */
8214 /* First do the assignment, then return converted constant. */
8219 }
8221 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8222 constants (if x has signed type, the sign bit cannot be set
8223 in c). This folds extension into the BIT_AND_EXPR. */
8228 {
8238 <= HOST_BITS_PER_WIDE_INT
8240 {
8247 #ifdef LOAD_EXTEND_OP
8249 && !flag_syntax_only
8252 {
8256 }
8257 #endif
8258 }
8260 {
8266 }
8267 }
8269 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8270 when one of the new casts will fold away. Conservatively we assume
8271 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8277 {
8283 }
8285 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8286 of the same precision, and X is an integer type not narrower than
8287 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8294 {
8299 }
8326 /* Convert fabs((double)float) into (double)fabsf(float). */
8329 {
8334 targ0));
8335 }
8336 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8342 /* Strip sign ops from argument. */
8344 {
8348 }
8355 {
8360 }
8362 {
8367 }
8377 /* Convert ~ (-A) to A - 1. */
8381 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8388 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8401 /* Perform BIT_NOT_EXPR on each element individually. */
8403 {
8408 {
8410 {
8416 }
8417 else
8420 }
8423 }
8428 /* The argument to invert_truthvalue must have Boolean type. */
8432 /* Note that the operand of this must be an int
8433 and its values must be 0 or 1.
8434 ("true" is a fixed value perhaps depending on the language,
8435 but we don't handle values other than 1 correctly yet.) */
8450 {
8458 }
8460 {
8464 }
8466 {
8470 {
8479 }
8480 }
8492 {
8500 }
8502 {
8506 }
8508 {
8512 {
8521 }
8522 }
8528 }
8530 /* Fold a binary expression of code CODE and type TYPE with operands
8531 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8532 Return the folded expression if folding is successful. Otherwise,
8533 return NULL_TREE. */
8535 static tree
8537 {
8544 else
8547 /* MIN (MAX (a, b), b) == b. */
8552 /* MIN (MAX (b, a), b) == b. */
8558 /* MIN (a, MAX (a, b)) == a. */
8564 /* MIN (a, MAX (b, a)) == a. */
8571 }
8573 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8574 by changing CODE to reduce the magnitude of constants involved in
8575 ARG0 of the comparison.
8576 Returns a canonicalized comparison tree if a simplification was
8577 possible, otherwise returns NULL_TREE.
8578 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8579 valid if signed overflow is undefined. */
8581 static tree
8585 {
8591 /* Match A +- CST code arg1 and CST code arg1. */
8598 /* Identify the constant in arg0 and its sign. */
8601 else
8605 /* Overflowed constants and zero will cause problems. */
8610 /* See if we can reduce the magnitude of the constant in
8611 arg0 by changing the comparison code. */
8613 {
8614 /* CST <= arg1 -> CST-1 < arg1. */
8617 /* -CST < arg1 -> -CST-1 <= arg1. */
8620 /* CST > arg1 -> CST-1 >= arg1. */
8623 /* -CST >= arg1 -> -CST-1 > arg1. */
8626 else
8628 /* arg1 code' CST' might be more canonical. */
8630 }
8631 else
8632 {
8633 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8637 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8641 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8645 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8649 else
8652 }
8654 /* Now build the constant reduced in magnitude. */
8660 /* If swapping might yield to a more canonical form, do so. */
8663 else
8665 }
8667 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8668 overflow further. Try to decrease the magnitude of constants involved
8669 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8670 and put sole constants at the second argument position.
8671 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8673 static tree
8676 {
8677 tree t;
8682 /* In principle pointers also have undefined overflow behavior,
8683 but that causes problems elsewhere. */
8688 /* Try canonicalization by simplifying arg0. */
8693 {
8697 }
8699 /* Try canonicalization by simplifying arg1 using the swapped
8700 comparison. */
8708 }
8710 /* Subroutine of fold_binary. This routine performs all of the
8711 transformations that are common to the equality/inequality
8712 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8713 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8714 fold_binary should call fold_binary. Fold a comparison with
8715 tree code CODE and type TYPE with operands OP0 and OP1. Return
8716 the folded comparison or NULL_TREE. */
8718 static tree
8720 {
8733 /* If one arg is a real or integer constant, put it last. */
8737 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8744 {
8748 tree lhs;
8755 /* If the constant operation overflowed this can be
8756 simplified as a comparison against INT_MAX/INT_MIN. */
8759 {
8763 /* Get the sign of the constant on the lhs if the
8764 operation were VARIABLE + CONST1. */
8768 /* The sign of the constant determines if we overflowed
8769 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8770 Canonicalize to the INT_MIN overflow by swapping the comparison
8771 if necessary. */
8775 /* We now can look at the canonicalized case
8776 VARIABLE + 1 CODE2 INT_MIN
8777 and decide on the result. */
8786 }
8791 {
8793 "when changing X +- C1 cmp C2 to "
8795 WARN_STRICT_OVERFLOW_COMPARISON);
8797 }
8798 }
8800 /* For comparisons of pointers we can decompose it to a compile time
8801 comparison of the base objects and the offsets into the object.
8802 This requires at least one operand being an ADDR_EXPR to do more
8803 than the operand_equal_p test below. */
8807 {
8814 /* Get base and offset for the access. Strip ADDR_EXPR for
8815 get_inner_reference, but put it back by stripping INDIRECT_REF
8816 off the base object if possible. */
8819 {
8825 else
8827 }
8831 {
8835 /* We have to make sure to have an indirect/non-indirect base1
8836 just the same as we did for base0. */
8842 }
8846 /* If we have equivalent bases we might be able to simplify. */
8849 {
8850 /* We can fold this expression to a constant if the non-constant
8851 offset parts are equal. */
8855 {
8857 {
8871 }
8872 }
8873 /* We can simplify the comparison to a comparison of the variable
8874 offset parts if the constant offset parts are equal.
8875 Be careful to use signed size type here because otherwise we
8876 mess with array offsets in the wrong way. This is possible
8877 because pointer arithmetic is restricted to retain within an
8878 object and overflow on pointer differences is undefined as of
8879 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8881 {
8882 tree signed_size_type_node;
8885 /* By converting to signed size type we cover middle-end pointer
8886 arithmetic which operates on unsigned pointer types of size
8887 type size and ARRAY_REF offsets which are properly sign or
8888 zero extended from their type in case it is narrower than
8889 size type. */
8892 else
8896 else
8900 }
8901 }
8902 }
8904 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8905 same object, then we can fold this to a comparison of the two offsets in
8906 signed size type. This is possible because pointer arithmetic is
8907 restricted to retain within an object and overflow on pointer differences
8908 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8910 We check flag_wrapv directly because pointers types are unsigned,
8911 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8912 normally what we want to avoid certain odd overflow cases, but
8913 not here. */
8915 && !flag_wrapv
8917 {
8923 {
8924 tree signed_size_type_node;
8927 /* By converting to signed size type we cover middle-end pointer
8928 arithmetic which operates on unsigned pointer types of size
8929 type size and ARRAY_REF offsets which are properly sign or
8930 zero extended from their type in case it is narrower than
8931 size type. */
8934 else
8938 else
8942 }
8943 }
8945 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8946 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8947 the resulting offset is smaller in absolute value than the
8948 original one. */
8956 {
8961 tree cst;
8963 "occur when combining constants around "
8966 /* Put the constant on the side where it doesn't overflow and is
8967 of lower absolute value than before. */
8973 {
8976 variable1,
8979 }
8986 {
8991 variable2);
8992 }
8993 }
8995 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8996 signed arithmetic case. That form is created by the compiler
8997 often enough for folding it to be of value. One example is in
8998 computing loop trip counts after Operator Strength Reduction. */
9004 {
9013 "eliminating multiplication in comparison "
9015 WARN_STRICT_OVERFLOW_COMPARISON);
9017 /* If const1 is negative we swap the sense of the comparison. */
9022 }
9029 {
9037 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9042 /* (-a) CMP (-b) -> b CMP a */
9049 {
9050 REAL_VALUE_TYPE cst;
9053 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9060 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9061 /* a CMP (-0) -> a CMP 0 */
9066 /* x != NaN is always true, other ops are always false. */
9069 {
9072 }
9074 /* Fold comparisons against infinity. */
9076 {
9080 }
9081 }
9083 /* If this is a comparison of a real constant with a PLUS_EXPR
9084 or a MINUS_EXPR of a real constant, we can convert it into a
9085 comparison with a revised real constant as long as no overflow
9086 occurs when unsafe_math_optimizations are enabled. */
9098 /* Likewise, we can simplify a comparison of a real constant with
9099 a MINUS_EXPR whose first operand is also a real constant, i.e.
9100 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9101 floating-point types only if -fassociative-math is set. */
9112 /* Fold comparisons against built-in math functions. */
9114 && flag_unsafe_math_optimizations
9116 {
9120 {
9124 }
9125 }
9126 }
9131 {
9132 /* If we are widening one operand of an integer comparison,
9133 see if the other operand is similarly being widened. Perhaps we
9134 can do the comparison in the narrower type. */
9139 /* Or if we are changing signedness. */
9143 }
9145 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9146 constant, we can simplify it. */
9151 {
9155 }
9157 /* Simplify comparison of something with itself. (For IEEE
9158 floating-point, we can only do some of these simplifications.) */
9160 {
9162 {
9177 /* For NE, we can only do this simplification if integer
9178 or we don't honor IEEE floating point NaNs. */
9182 /* ... fall through ... */
9188 }
9189 }
9191 /* If we are comparing an expression that just has comparisons
9192 of two integer values, arithmetic expressions of those comparisons,
9193 and constants, we can simplify it. There are only three cases
9194 to check: the two values can either be equal, the first can be
9195 greater, or the second can be greater. Fold the expression for
9196 those three values. Since each value must be 0 or 1, we have
9197 eight possibilities, each of which corresponds to the constant 0
9198 or 1 or one of the six possible comparisons.
9200 This handles common cases like (a > b) == 0 but also handles
9201 expressions like ((x > y) - (y > x)) > 0, which supposedly
9202 occur in macroized code. */
9205 {
9210 /* Don't handle degenerate cases here; they should already
9211 have been handled anyway. */
9220 {
9224 /* We can't just pass T to eval_subst in case cval1 or cval2
9225 was the same as ARG1. */
9227 tree high_result
9231 arg1);
9232 tree equal_result
9236 arg1);
9237 tree low_result
9241 arg1);
9243 /* All three of these results should be 0 or 1. Confirm they are.
9244 Then use those values to select the proper code to use. */
9249 {
9250 /* Make a 3-bit mask with the high-order bit being the
9251 value for `>', the next for '=', and the low for '<'. */
9255 {
9257 /* Always false. */
9278 /* Always true. */
9280 }
9285 }
9286 }
9287 }
9289 /* Fold a comparison of the address of COMPONENT_REFs with the same
9290 type and component to a comparison of the address of the base
9291 object. In short, &x->a OP &y->a to x OP y and
9292 &x->a OP &y.a to x OP &y */
9297 {
9301 {
9307 }
9308 }
9310 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9311 into a single range test. */
9319 {
9323 }
9325 /* Fold ~X op ~Y as Y op X. */
9328 {
9333 }
9335 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9338 {
9344 }
9347 }
9350 /* Subroutine of fold_binary. Optimize complex multiplications of the
9351 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9352 argument EXPR represents the expression "z" of type TYPE. */
9354 static tree
9356 {
9361 {
9364 }
9366 {
9369 }
9370 else
9371 {
9375 }
9384 }
9387 /* Fold a binary expression of code CODE and type TYPE with operands
9388 OP0 and OP1. Return the folded expression if folding is
9389 successful. Otherwise, return NULL_TREE. */
9391 tree
9393 {
9408 /* Strip any conversions that don't change the mode. This is
9409 safe for every expression, except for a comparison expression
9410 because its signedness is derived from its operands. So, in
9411 the latter case, only strip conversions that don't change the
9412 signedness.
9414 Note that this is done as an internal manipulation within the
9415 constant folder, in order to find the simplest representation
9416 of the arguments so that their form can be studied. In any
9417 cases, the appropriate type conversions should be put back in
9418 the tree that will get out of the constant folder. */
9421 {
9424 }
9425 else
9426 {
9429 }
9431 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9432 constant but we can't do arithmetic on them. */
9439 {
9441 {
9442 /* Make sure type and arg0 have the same saturating flag. */
9446 }
9449 else
9453 {
9457 }
9458 }
9460 /* If this is a commutative operation, and ARG0 is a constant, move it
9461 to ARG1 to reduce the number of tests below. */
9466 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9468 First check for cases where an arithmetic operation is applied to a
9469 compound, conditional, or comparison operation. Push the arithmetic
9470 operation inside the compound or conditional to see if any folding
9471 can then be done. Convert comparison to conditional for this purpose.
9472 The also optimizes non-constant cases that used to be done in
9473 expand_expr.
9475 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9476 one of the operands is a comparison and the other is a comparison, a
9477 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9478 code below would make the expression more complex. Change it to a
9479 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9480 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9492 {
9496 boolean_type_node,
9504 }
9508 {
9520 {
9526 }
9529 {
9535 }
9536 }
9539 {
9541 /* 0 +p index -> (type)index */
9545 /* PTR +p 0 -> PTR */
9549 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9556 /* index +p PTR -> PTR +p index */
9563 /* (PTR +p B) +p A -> PTR +p (B + A) */
9565 {
9566 tree inner;
9574 }
9576 /* PTR_CST +p CST -> CST1 */
9580 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9581 of the array. Loop optimizer sometimes produce this type of
9582 expressions. */
9584 {
9588 }
9593 /* PTR + INT -> (INT)(PTR p+ INT) */
9598 arg0,
9600 /* INT + PTR -> (INT)(PTR p+ INT) */
9605 arg1,
9607 /* A + (-B) -> A - B */
9612 /* (-A) + B -> B - A */
9620 {
9621 /* Convert ~A + 1 to -A. */
9626 /* ~X + X is -1. */
9629 {
9634 {
9637 }
9638 }
9640 /* X + ~X is -1. */
9643 {
9648 {
9651 }
9652 }
9653 }
9655 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9656 same or one. Make sure type is not saturating.
9657 fold_plusminus_mult_expr will re-associate. */
9662 {
9666 }
9669 {
9673 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9674 with a constant, and the two constants have no bits in common,
9675 we should treat this as a BIT_IOR_EXPR since this may produce more
9676 simplifications. */
9684 {
9687 }
9689 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9690 (plus (plus (mult) (mult)) (foo)) so that we can
9691 take advantage of the factoring cases below. */
9698 {
9704 else
9726 parg1)));
9727 }
9728 }
9729 else
9730 {
9731 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9735 /* Likewise if the operands are reversed. */
9739 /* Convert X + -C into X - C. */
9742 {
9748 }
9750 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9751 to __complex__ ( x, y ). This is not the same for SNaNs or
9752 if signed zeros are involved. */
9756 {
9763 {
9767 {
9773 }
9775 {
9781 }
9782 }
9783 }
9791 /* Convert x+x into x*2.0. */
9797 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9798 We associate floats only if the user has specified
9799 -fassociative-math. */
9803 {
9808 {
9809 tree tree0;
9812 }
9813 }
9814 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9815 We associate floats only if the user has specified
9816 -fassociative-math. */
9820 {
9825 {
9826 tree tree0;
9829 }
9830 }
9831 }
9833 bit_rotate:
9834 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9835 is a rotate of A by C1 bits. */
9836 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9837 is a rotate of A by B bits. */
9838 {
9847 {
9866 {
9874 TYPE_PRECISION
9879 ? LROTATE_EXPR
9882 }
9884 {
9892 TYPE_PRECISION
9897 ? LROTATE_EXPR
9900 }
9901 }
9902 }
9904 associate:
9905 /* In most languages, can't associate operations on floats through
9906 parentheses. Rather than remember where the parentheses were, we
9907 don't associate floats at all, unless the user has specified
9908 -fassociative-math.
9909 And, we need to make sure type is not saturating. */
9913 {
9918 /* Split both trees into variables, constants, and literals. Then
9919 associate each group together, the constants with literals,
9920 then the result with variables. This increases the chances of
9921 literals being recombined later and of generating relocatable
9922 expressions for the sum of a constant and literal. */
9927 /* With undefined overflow we can only associate constants
9928 with one variable. */
9932 {
9940 /* The only case we can still associate with two variables
9941 is if they are the same, modulo negation. */
9944 }
9946 /* Only do something if we found more than two objects. Otherwise,
9947 nothing has changed and we risk infinite recursion. */
9953 {
9954 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9963 /* Preserve the MINUS_EXPR if the negative part of the literal is
9964 greater than the positive part. Otherwise, the multiplicative
9965 folding code (i.e extract_muldiv) may be fooled in case
9966 unsigned constants are subtracted, like in the following
9967 example: ((X*2 + 4) - 8U)/2. */
9969 {
9973 {
9977 }
9978 else
9979 {
9983 }
9984 }
9986 {
9991 else
9992 {
9998 }
9999 }
10004 }
10005 }
10010 /* Pointer simplifications for subtraction, simple reassociations. */
10012 {
10013 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10016 {
10024 }
10025 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10027 {
10033 }
10034 }
10035 /* A - (-B) -> A + B */
10038 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10046 /* Convert -A - 1 to ~A. */
10054 /* Convert -1 - A to ~A. */
10060 {
10066 /* Fold A - (A & B) into ~B & A. */
10069 {
10071 {
10076 }
10078 {
10083 }
10084 }
10086 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10087 any power of 2 minus 1. */
10092 {
10098 {
10102 }
10103 }
10104 }
10106 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10110 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10111 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10112 (-ARG1 + ARG0) reduces to -ARG1. */
10116 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10117 __complex__ ( x, -y ). This is not the same for SNaNs or if
10118 signed zeros are involved. */
10122 {
10129 {
10133 {
10135 arg1r ? arg1r
10140 }
10142 {
10146 arg1i ? arg1i
10149 }
10150 }
10151 }
10153 /* Fold &x - &x. This can happen from &x.foo - &x.
10154 This is unsafe for certain floats even in non-IEEE formats.
10155 In IEEE, it is unsafe because it does wrong for NaNs.
10156 Also note that operand_equal_p is always false if an operand
10157 is volatile. */
10163 /* A - B -> A + (-B) if B is easily negatable. */
10166 /* Avoid this transformation if B is a positive REAL_CST. */
10174 /* Try folding difference of addresses. */
10175 {
10176 HOST_WIDE_INT diff;
10182 }
10184 /* Fold &a[i] - &a[j] to i-j. */
10189 {
10194 {
10202 }
10203 }
10211 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10212 same or one. Make sure type is not saturating.
10213 fold_plusminus_mult_expr will re-associate. */
10218 {
10222 }
10227 /* (-A) * (-B) -> A * B */
10238 {
10243 /* Transform x * -1 into -x. */
10246 /* Transform x * -C into -x * C if x is easily negatable. */
10255 /* (a * (1 << b)) is (a << b) */
10271 {
10274 "occur when simplifying "
10276 WARN_STRICT_OVERFLOW_MISC);
10278 }
10280 /* Optimize z * conj(z) for integer complex numbers. */
10287 }
10288 else
10289 {
10290 /* Maybe fold x * 0 to 0. The expressions aren't the same
10291 when x is NaN, since x * 0 is also NaN. Nor are they the
10292 same in modes with signed zeros, since multiplying a
10293 negative value by 0 gives -0, not +0. */
10298 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10303 /* Transform x * -1.0 into -x. */
10308 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10309 the result for floating point types due to rounding so it is applied
10310 only if -fassociative-math was specify. */
10315 {
10321 }
10323 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10325 {
10328 {
10331 }
10332 }
10334 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10335 This is not the same for NaNs or if signed zeros are
10336 involved. */
10342 {
10354 }
10356 /* Optimize z * conj(z) for floating point complex numbers.
10357 Guarded by flag_unsafe_math_optimizations as non-finite
10358 imaginary components don't produce scalar results. */
10369 {
10373 /* Optimizations of root(...)*root(...). */
10375 {
10380 /* Optimize sqrt(x)*sqrt(x) as x. */
10386 /* Optimize root(x)*root(y) as root(x*y). */
10390 }
10392 /* Optimize expN(x)*expN(y) as expN(x+y). */
10394 {
10400 }
10402 /* Optimizations of pow(...)*pow(...). */
10406 {
10412 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10414 {
10418 }
10420 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10422 {
10426 }
10427 }
10429 /* Optimize tan(x)*cos(x) as sin(x). */
10438 {
10443 }
10445 /* Optimize x*pow(x,c) as pow(x,c+1). */
10449 {
10455 {
10457 REAL_VALUE_TYPE c;
10458 tree arg;
10464 }
10465 }
10467 /* Optimize pow(x,c)*x as pow(x,c+1). */
10471 {
10477 {
10479 REAL_VALUE_TYPE c;
10480 tree arg;
10486 }
10487 }
10489 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10492 {
10496 {
10499 }
10500 }
10501 }
10502 }
10506 bit_ior:
10514 /* ~X | X is -1. */
10517 {
10521 }
10523 /* X | ~X is -1. */
10526 {
10530 }
10532 /* Canonicalize (X & C1) | C2. */
10536 {
10544 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10549 {
10553 }
10554 else
10555 {
10559 }
10561 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10566 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
10576 arg1);
10577 }
10579 /* (X & Y) | Y is (X, Y). */
10583 /* (X & Y) | X is (Y, X). */
10588 /* X | (X & Y) is (Y, X). */
10593 /* X | (Y & X) is (Y, X). */
10603 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10605 This results in more efficient code for machines without a NAND
10606 instruction. Combine will canonicalize to the first form
10607 which will allow use of NAND instructions provided by the
10608 backend if they exist. */
10611 {
10616 }
10618 /* See if this can be simplified into a rotate first. If that
10619 is unsuccessful continue in the association code. */
10630 /* ~X ^ X is -1. */
10633 {
10637 }
10639 /* X ^ ~X is -1. */
10642 {
10646 }
10648 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10649 with a constant, and the two constants have no bits in common,
10650 we should treat this as a BIT_IOR_EXPR since this may produce more
10651 simplifications. */
10659 {
10662 }
10664 /* (X | Y) ^ X -> Y & ~ X*/
10667 {
10670 arg1);
10674 }
10676 /* (Y | X) ^ X -> Y & ~ X*/
10679 {
10682 arg1);
10686 }
10688 /* X ^ (X | Y) -> Y & ~ X*/
10691 {
10694 arg0);
10698 }
10700 /* X ^ (Y | X) -> Y & ~ X*/
10703 {
10706 arg0);
10710 }
10712 /* Convert ~X ^ ~Y to X ^ Y. */
10719 /* Convert ~X ^ C to X ^ ~C. */
10726 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10733 /* Fold (X & Y) ^ Y as ~X & Y. */
10736 {
10741 }
10742 /* Fold (X & Y) ^ X as ~Y & X. */
10746 {
10751 }
10752 /* Fold X ^ (X & Y) as X & ~Y. */
10755 {
10760 }
10761 /* Fold X ^ (Y & X) as ~Y & X. */
10765 {
10770 }
10772 /* See if this can be simplified into a rotate first. If that
10773 is unsuccessful continue in the association code. */
10784 /* ~X & X is always zero. */
10789 /* X & ~X is always zero. */
10794 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10804 /* (X | Y) & Y is (X, Y). */
10808 /* (X | Y) & X is (Y, X). */
10813 /* X & (X | Y) is (Y, X). */
10818 /* X & (Y | X) is (Y, X). */
10824 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10828 {
10834 }
10835 /* Fold ~X & 1 as (X & 1) == 0. */
10838 {
10844 }
10846 /* Fold (X ^ Y) & Y as ~X & Y. */
10849 {
10854 }
10855 /* Fold (X ^ Y) & X as ~Y & X. */
10859 {
10864 }
10865 /* Fold X & (X ^ Y) as X & ~Y. */
10868 {
10873 }
10874 /* Fold X & (Y ^ X) as ~Y & X. */
10878 {
10883 }
10888 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10891 {
10892 unsigned int prec
10899 }
10901 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10903 This results in more efficient code for machines without a NOR
10904 instruction. Combine will canonicalize to the first form
10905 which will allow use of NOR instructions provided by the
10906 backend if they exist. */
10909 {
10914 }
10919 /* Don't touch a floating-point divide by zero unless the mode
10920 of the constant can represent infinity. */
10926 /* Optimize A / A to 1.0 if we don't care about
10927 NaNs or Infinities. Skip the transformation
10928 for non-real operands. */
10933 {
10937 }
10939 /* The complex version of the above A / A optimization. */
10942 {
10946 {
10948 /* omit_two_operands will call fold_convert for us. */
10950 }
10951 }
10953 /* (-A) / (-B) -> A / B */
10963 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
10968 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
10973 /* If ARG1 is a constant, we can convert this to a multiply by the
10974 reciprocal. This does not have the same rounding properties,
10975 so only do this if -freciprocal-math. We can actually
10976 always safely do it if ARG1 is a power of two, but it's hard to
10977 tell if it is or not in a portable manner. */
10979 {
10984 /* Find the reciprocal if optimizing and the result is exact. */
10986 {
10987 REAL_VALUE_TYPE r;
10990 {
10994 }
10995 }
10996 }
10997 /* Convert A/B/C to A/(B*C). */
11004 /* Convert A/(B/C) to (A/B)*C. */
11012 /* Convert C1/(X*C2) into (C1/C2)/X. */
11017 {
11023 }
11026 {
11030 /* Optimize sin(x)/cos(x) as tan(x). */
11036 {
11041 }
11043 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11049 {
11053 {
11057 }
11058 }
11060 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11061 NaNs or Infinities. */
11065 {
11072 {
11077 }
11078 }
11080 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11081 NaNs or Infinities. */
11085 {
11092 {
11096 {
11100 tmp);
11101 }
11102 }
11103 }
11105 /* Optimize pow(x,c)/x as pow(x,c-1). */
11109 {
11115 {
11117 REAL_VALUE_TYPE c;
11118 tree arg;
11124 }
11125 }
11127 /* Optimize a/root(b/c) into a*root(c/b). */
11129 {
11133 {
11142 }
11143 }
11145 /* Optimize x/expN(y) into x*expN(-y). */
11147 {
11152 }
11154 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11158 {
11165 }
11166 }
11171 /* Simplify A / (B << N) where A and B are positive and B is
11172 a power of 2, to A >> (N + log2(B)). */
11177 {
11180 {
11187 WARN_STRICT_OVERFLOW_MISC);
11193 }
11194 }
11195 /* Fall thru */
11204 /* X / -1 is -X. */
11211 /* Convert -A / -B to A / B when the type is signed and overflow is
11212 undefined. */
11216 {
11219 "when distributing negation across "
11221 WARN_STRICT_OVERFLOW_MISC);
11225 }
11229 {
11232 "when distributing negation across "
11234 WARN_STRICT_OVERFLOW_MISC);
11237 }
11239 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11240 operation, EXACT_DIV_EXPR.
11242 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11243 At one time others generated faster code, it's not clear if they do
11244 after the last round to changes to the DIV code in expmed.c. */
11253 {
11257 WARN_STRICT_OVERFLOW_MISC);
11259 }
11267 /* X % 1 is always zero, but be sure to preserve any side
11268 effects in X. */
11272 /* X % 0, return X % 0 unchanged so that we can get the
11273 proper warnings and errors. */
11277 /* 0 % X is always zero, but be sure to preserve any side
11278 effects in X. Place this after checking for X == 0. */
11282 /* X % -1 is zero. */
11289 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11290 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11295 {
11297 /* Also optimize A % (C << N) where C is a power of 2,
11298 to A & ((C << N) - 1). */
11303 {
11308 "occur when simplifying "
11310 WARN_STRICT_OVERFLOW_MISC);
11314 }
11315 }
11317 /* X % -C is the same as X % C. */
11324 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11329 /* X % -Y is the same as X % Y. */
11340 {
11344 WARN_STRICT_OVERFLOW_MISC);
11346 }
11357 /* Optimize -1 >> x for arithmetic right shifts. */
11360 /* ... fall through ... */
11363 shift:
11369 /* Since negative shift count is not well-defined,
11370 don't try to compute it in the compiler. */
11374 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11379 {
11383 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11384 being well defined. */
11386 {
11391 else
11393 }
11397 }
11399 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11400 into x & ((unsigned)-1 >> c) for unsigned types. */
11408 {
11411 tree lshift;
11412 tree arg00;
11415 {
11422 }
11423 }
11425 /* Rewrite an LROTATE_EXPR by a constant into an
11426 RROTATE_EXPR by a new constant. */
11428 {
11433 }
11435 /* If we have a rotate of a bit operation with the rotate count and
11436 the second operand of the bit operation both constant,
11437 permute the two operations. */
11449 /* Two consecutive rotates adding up to the width of the mode can
11450 be ignored. */
11487 /* Note that the operands of this must be ints
11488 and their values must be 0 or 1.
11489 ("true" is a fixed value perhaps depending on the language.) */
11490 /* If first arg is constant zero, return it. */
11494 /* If either arg is constant true, drop it. */
11498 /* Preserve sequence points. */
11501 /* If second arg is constant zero, result is zero, but first arg
11502 must be evaluated. */
11505 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11506 case will be handled here. */
11510 /* !X && X is always false. */
11514 /* X && !X is always false. */
11519 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
11520 means A >= Y && A != MAX, but in this case we know that
11521 A < X <= MAX. */
11525 {
11533 }
11535 truth_andor:
11536 /* We only do these simplifications if we are optimizing. */
11540 /* Check for things like (A || B) && (A || C). We can convert this
11541 to A || (B && C). Note that either operator can be any of the four
11542 truth and/or operations and the transformation will still be
11543 valid. Also note that we only care about order for the
11544 ANDIF and ORIF operators. If B contains side effects, this
11545 might change the truth-value of A. */
11552 {
11572 /* This case if tricky because we must either have commutative
11573 operators or else A10 must not have side-effects. */
11579 a01);
11580 }
11582 /* See if we can build a range comparison. */
11586 /* Check for the possibility of merging component references. If our
11587 lhs is another similar operation, try to merge its rhs with our
11588 rhs. Then try to merge our lhs and rhs. */
11600 /* Note that the operands of this must be ints
11601 and their values must be 0 or true.
11602 ("true" is a fixed value perhaps depending on the language.) */
11603 /* If first arg is constant true, return it. */
11607 /* If either arg is constant zero, drop it. */
11611 /* Preserve sequence points. */
11614 /* If second arg is constant true, result is true, but we must
11615 evaluate first arg. */
11618 /* Likewise for first arg, but note this only occurs here for
11619 TRUTH_OR_EXPR. */
11623 /* !X || X is always true. */
11627 /* X || !X is always true. */
11635 /* If the second arg is constant zero, drop it. */
11638 /* If the second arg is constant true, this is a logical inversion. */
11640 {
11641 /* Only call invert_truthvalue if operand is a truth value. */
11644 else
11647 }
11648 /* Identical arguments cancel to zero. */
11652 /* !X ^ X is always true. */
11657 /* X ^ !X is always true. */
11670 /* bool_var != 0 becomes bool_var. */
11675 /* bool_var == 1 becomes bool_var. */
11680 /* bool_var != 1 becomes !bool_var. */
11685 /* bool_var == 0 becomes !bool_var. */
11690 /* If this is an equality comparison of the address of two non-weak,
11691 unaliased symbols neither of which are extern (since we do not
11692 have access to attributes for externs), then we know the result. */
11705 {
11706 /* We know that we're looking at the address of two
11707 non-weak, unaliased, static _DECL nodes.
11709 It is both wasteful and incorrect to call operand_equal_p
11710 to compare the two ADDR_EXPR nodes. It is wasteful in that
11711 all we need to do is test pointer equality for the arguments
11712 to the two ADDR_EXPR nodes. It is incorrect to use
11713 operand_equal_p as that function is NOT equivalent to a
11714 C equality test. It can in fact return false for two
11715 objects which would test as equal using the C equality
11716 operator. */
11720 type);
11721 }
11723 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
11724 a MINUS_EXPR of a constant, we can convert it into a comparison with
11725 a revised constant as long as no overflow occurs. */
11737 /* Similarly for a NEGATE_EXPR. */
11745 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11754 /* Transform comparisons of the form X +- C CMP X. */
11760 {
11767 else
11770 }
11772 /* If we have X - Y == 0, we can convert that to X == Y and similarly
11773 for !=. Don't do this for ordered comparisons due to overflow. */
11779 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11784 /* If this is an EQ or NE comparison with zero and ARG0 is
11785 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11786 two operations, but the latter can be done in one less insn
11787 on machines that have only two-operand insns or on which a
11788 constant cannot be the first operand. */
11791 {
11796 return
11802 integer_one_node)),
11803 arg1);
11806 return
11812 integer_one_node)),
11813 arg1);
11814 }
11816 /* If this is an NE or EQ comparison of zero against the result of a
11817 signed MOD operation whose second operand is a power of 2, make
11818 the MOD operation unsigned since it is simpler and equivalent. */
11826 {
11836 }
11838 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11839 C1 is a valid shift constant, and C2 is a power of two, i.e.
11840 a single bit. */
11844 == INTEGER_CST
11847 {
11852 /* Check for a valid shift count. */
11855 {
11859 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11860 can be rewritten as (X & (C2 << C1)) != 0. */
11862 {
11866 }
11867 /* Otherwise, for signed (arithmetic) shifts,
11868 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11869 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11873 /* Otherwise, of unsigned (logical) shifts,
11874 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11875 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11876 else
11880 arg000);
11881 }
11882 }
11884 /* If this is an NE comparison of zero with an AND of one, remove the
11885 comparison since the AND will give the correct value. */
11892 /* If we have (A & C) == C where C is a power of 2, convert this into
11893 (A & C) != 0. Similarly for NE_EXPR. */
11899 integer_zero_node));
11901 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11902 bit, then fold the expression into A < 0 or A >= 0. */
11907 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11908 Similarly for NE_EXPR. */
11912 {
11921 }
11923 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11924 Similarly for NE_EXPR. */
11928 {
11935 }
11937 /* If this is a comparison of a field, we may be able to simplify it. */
11940 /* Handle the constant case even without -O
11941 to make sure the warnings are given. */
11943 {
11947 }
11949 /* Optimize comparisons of strlen vs zero to a compare of the
11950 first character of the string vs zero. To wit,
11951 strlen(ptr) == 0 => *ptr == 0
11952 strlen(ptr) != 0 => *ptr != 0
11953 Other cases should reduce to one of these two (or a constant)
11954 due to the return value of strlen being unsigned. */
11957 {
11965 {
11969 }
11970 }
11972 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11973 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11977 {
11984 {
11986 {
11989 }
11992 }
11993 }
11995 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12001 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12006 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12013 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12021 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12022 (X & C) == 0 when C is a single bit. */
12027 {
12033 }
12035 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12036 constant C is a power of two, i.e. a single bit. */
12043 {
12047 }
12049 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12050 when is C is a power of two, i.e. a single bit. */
12057 {
12063 }
12067 {
12070 }
12072 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12079 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12082 {
12094 arg01),
12102 arg01),
12110 arg00),
12118 arg00),
12120 }
12124 {
12131 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12132 operand_equal_p guarantees no side-effects so we don't need
12133 to use omit_one_operand on Z. */
12143 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12150 arg10);
12151 }
12153 /* Attempt to simplify equality/inequality comparisons of complex
12154 values. Only lower the comparison if the result is known or
12155 can be simplified to a single scalar comparison. */
12160 {
12165 {
12168 }
12169 else
12170 {
12173 }
12176 {
12179 }
12180 else
12181 {
12184 }
12188 {
12190 {
12195 }
12196 else
12197 {
12202 }
12203 }
12207 {
12209 {
12214 }
12215 else
12216 {
12221 }
12222 }
12223 }
12235 /* Transform comparisons of the form X +- C CMP X. */
12242 {
12249 else
12252 /* (X - c) > X becomes false. */
12256 {
12260 "occur when assuming that (X - c) > X "
12262 WARN_STRICT_OVERFLOW_ALL);
12264 }
12266 /* Likewise (X + c) < X becomes false. */
12270 {
12274 "occur when assuming that "
12276 WARN_STRICT_OVERFLOW_ALL);
12278 }
12280 /* Convert (X - c) <= X to true. */
12285 {
12289 "occur when assuming that "
12291 WARN_STRICT_OVERFLOW_ALL);
12293 }
12295 /* Convert (X + c) >= X to true. */
12300 {
12304 "occur when assuming that "
12306 WARN_STRICT_OVERFLOW_ALL);
12308 }
12311 {
12312 /* Convert X + c > X and X - c < X to true for integers. */
12316 {
12319 "not occur when assuming that "
12321 WARN_STRICT_OVERFLOW_ALL);
12323 }
12328 {
12331 "not occur when assuming that "
12333 WARN_STRICT_OVERFLOW_ALL);
12335 }
12337 /* Convert X + c <= X and X - c >= X to false for integers. */
12341 {
12344 "not occur when assuming that "
12346 WARN_STRICT_OVERFLOW_ALL);
12348 }
12353 {
12356 "not occur when assuming that "
12358 WARN_STRICT_OVERFLOW_ALL);
12360 }
12361 }
12362 }
12364 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
12365 This transformation affects the cases which are handled in later
12366 optimizations involving comparisons with non-negative constants. */
12370 {
12372 {
12377 }
12379 {
12384 }
12385 }
12387 /* Comparisons with the highest or lowest possible integer of
12388 the specified precision will have known values. */
12389 {
12397 {
12398 HOST_WIDE_INT signed_max_hi;
12403 {
12410 {
12414 }
12415 else
12416 {
12420 }
12421 }
12422 else
12423 {
12432 {
12435 }
12436 else
12437 {
12440 }
12441 }
12446 {
12459 /* The GE_EXPR and LT_EXPR cases above are not normally
12460 reached because of previous transformations. */
12464 }
12466 == max_hi
12469 {
12475 arg1);
12481 arg1);
12484 }
12486 == min_hi
12489 {
12504 }
12506 == min_hi
12509 {
12514 arg1);
12519 arg1);
12522 }
12527 /* We will flip the signedness of the comparison operator
12528 associated with the mode of arg1, so the sign bit is
12529 specified by this mode. Check that arg1 is the signed
12530 max associated with this sign bit. */
12532 /* signed_type does not work on pointer types. */
12534 {
12535 /* The following case also applies to X < signed_max+1
12536 and X >= signed_max+1 because previous transformations. */
12538 {
12539 tree st;
12544 }
12545 }
12546 }
12547 }
12549 /* If we are comparing an ABS_EXPR with a constant, we can
12550 convert all the cases into explicit comparisons, but they may
12551 well not be faster than doing the ABS and one comparison.
12552 But ABS (X) <= C is a range comparison, which becomes a subtraction
12553 and a comparison, and is probably faster. */
12567 /* Convert ABS_EXPR<x> >= 0 to true. */
12574 {
12577 "when simplifying comparison of "
12579 WARN_STRICT_OVERFLOW_CONDITIONAL);
12581 }
12583 /* Convert ABS_EXPR<x> < 0 to false. */
12588 {
12591 "when simplifying comparison of "
12593 WARN_STRICT_OVERFLOW_CONDITIONAL);
12595 }
12597 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12598 and similarly for >= into !=. */
12614 return
12633 {
12637 }
12639 /* If the first operand is NaN, the result is constant. */
12643 {
12645 ? integer_zero_node
12648 }
12650 /* If the second operand is NaN, the result is constant. */
12654 {
12656 ? integer_zero_node
12659 }
12661 /* Simplify unordered comparison of something with itself. */
12667 && !flag_trapping_math
12671 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12672 {
12683 }
12688 /* When pedantic, a compound expression can be neither an lvalue
12689 nor an integer constant expression. */
12692 /* Don't let (0, 0) be null pointer constant. */
12706 /* An ASSERT_EXPR should never be passed to fold_binary. */
12712 }
12714 /* Callback for walk_tree, looking for LABEL_EXPR.
12715 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
12716 Do not check the sub-tree of GOTO_EXPR. */
12718 static tree
12722 {
12724 {
12729 /* no break */
12732 }
12733 }
12735 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
12736 accessible from outside the sub-tree. Returns NULL_TREE if no
12737 addressable label is found. */
12739 static bool
12741 {
12743 }
12745 /* Fold a ternary expression of code CODE and type TYPE with operands
12746 OP0, OP1, and OP2. Return the folded expression if folding is
12747 successful. Otherwise, return NULL_TREE. */
12749 tree
12751 {
12752 tree tem;
12759 /* Strip any conversions that don't change the mode. This is safe
12760 for every expression, except for a comparison expression because
12761 its signedness is derived from its operands. So, in the latter
12762 case, only strip conversions that don't change the signedness.
12764 Note that this is done as an internal manipulation within the
12765 constant folder, in order to find the simplest representation of
12766 the arguments so that their form can be studied. In any cases,
12767 the appropriate type conversions should be put back in the tree
12768 that will get out of the constant folder. */
12770 {
12773 }
12776 {
12779 }
12782 {
12786 {
12792 }
12796 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12797 so all simple results must be passed through pedantic_non_lvalue. */
12799 {
12802 /* Only optimize constant conditions when the selected branch
12803 has the same type as the COND_EXPR. This avoids optimizing
12804 away "c ? x : throw", where the throw has a void type.
12805 Avoid throwing away that operand which contains label. */
12812 }
12816 /* If we have A op B ? A : C, we may be able to convert this to a
12817 simpler expression, depending on the operation and the values
12818 of B and C. Signed zeros prevent all of these transformations,
12819 for reasons given above each one.
12821 Also try swapping the arguments and inverting the conditional. */
12826 {
12830 }
12834 op2,
12837 {
12840 {
12844 }
12845 }
12847 /* If the second operand is simpler than the third, swap them
12848 since that produces better jump optimization results. */
12851 {
12852 /* See if this can be inverted. If it can't, possibly because
12853 it was a floating-point inequality comparison, don't do
12854 anything. */
12858 }
12860 /* Convert A ? 1 : 0 to simply A. */
12863 /* If we try to convert OP0 to our type, the
12864 call to fold will try to move the conversion inside
12865 a COND, which will recurse. In that case, the COND_EXPR
12866 is probably the best choice, so leave it alone. */
12870 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12871 over COND_EXPR in cases such as floating point comparisons. */
12878 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12883 {
12884 /* sign_bit_p only checks ARG1 bits within A's precision.
12885 If <sign bit of A> has wider type than A, bits outside
12886 of A's precision in <sign bit of A> need to be checked.
12887 If they are all 0, this optimization needs to be done
12888 in unsigned A's type, if they are all 1 in signed A's type,
12889 otherwise this can't be done. */
12894 {
12896 HOST_WIDE_INT mask_hi;
12898 tree tem_type;
12906 {
12910 }
12911 else
12912 {
12916 }
12918 {
12922 }
12923 else
12929 {
12932 }
12935 {
12938 }
12939 else
12941 }
12948 arg1)));
12949 }
12951 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12952 already handled above. */
12957 {
12966 }
12968 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12969 is probably obsolete because the first operand should be a
12970 truth value (that's why we have the two cases above), but let's
12971 leave it in until we can confirm this for all front-ends. */
12982 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12988 arg1);
12990 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12994 {
12995 /* Only perform transformation if ARG0 is easily inverted. */
13000 arg1);
13001 }
13003 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13007 {
13008 /* Only perform transformation if ARG0 is easily inverted. */
13013 op2);
13014 }
13016 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13022 op2);
13027 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13028 of fold_ternary on them. */
13037 {
13046 {
13051 else
13052 {
13054 tree value;
13058 }
13063 else
13065 }
13066 }
13072 }
13074 /* Perform constant folding and related simplification of EXPR.
13075 The related simplifications include x*1 => x, x*0 => 0, etc.,
13076 and application of the associative law.
13077 NOP_EXPR conversions may be removed freely (as long as we
13078 are careful not to change the type of the overall expression).
13079 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13080 but we can constant-fold them if they have constant operands. */
13082 #ifdef ENABLE_FOLD_CHECKING
13083 # define fold(x) fold_1 (x)
13085 static
13086 #endif
13087 tree
13089 {
13093 tree tem;
13095 /* Return right away if a constant. */
13099 /* CALL_EXPR-like objects with variable numbers of operands are
13100 treated specially. */
13102 {
13104 {
13107 }
13109 }
13113 {
13118 {
13136 }
13137 }
13140 {
13147 }
13149 #ifdef ENABLE_FOLD_CHECKING
13150 #undef fold
13156 /* When --enable-checking=fold, compute a digest of expr before
13157 and after actual fold call to see if fold did not accidentally
13158 change original expr. */
13160 tree
13162 {
13163 tree ret;
13166 htab_t ht;
13185 }
13187 void
13189 {
13192 htab_t ht;
13202 }
13204 static void
13206 {
13208 }
13210 static void
13212 {
13218 recursive_label:
13232 {
13233 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13237 }
13242 {
13243 /* Allow these fields to be modified. */
13244 tree tmp;
13251 {
13254 }
13255 }
13264 {
13267 {
13281 }
13285 {
13298 }
13315 {
13321 }
13326 {
13330 }
13341 {
13344 }
13354 }
13355 }
13357 /* Helper function for outputting the checksum of a tree T. When
13358 debugging with gdb, you can "define mynext" to be "next" followed
13359 by "call debug_fold_checksum (op0)", then just trace down till the
13360 outputs differ. */
13362 void
13364 {
13379 }
13381 #endif
13383 /* Fold a unary tree expression with code CODE of type TYPE with an
13384 operand OP0. Return a folded expression if successful. Otherwise,
13385 return a tree expression with code CODE of type TYPE with an
13386 operand OP0. */
13388 tree
13390 {
13391 tree tem;
13392 #ifdef ENABLE_FOLD_CHECKING
13395 htab_t ht;
13402 #endif
13408 #ifdef ENABLE_FOLD_CHECKING
13416 #endif
13418 }
13420 /* Fold a binary tree expression with code CODE of type TYPE with
13421 operands OP0 and OP1. Return a folded expression if successful.
13422 Otherwise, return a tree expression with code CODE of type TYPE
13423 with operands OP0 and OP1. */
13425 tree
13427 MEM_STAT_DECL)
13428 {
13429 tree tem;
13430 #ifdef ENABLE_FOLD_CHECKING
13436 htab_t ht;
13448 #endif
13454 #ifdef ENABLE_FOLD_CHECKING
13470 #endif
13472 }
13474 /* Fold a ternary tree expression with code CODE of type TYPE with
13475 operands OP0, OP1, and OP2. Return a folded expression if
13476 successful. Otherwise, return a tree expression with code CODE of
13477 type TYPE with operands OP0, OP1, and OP2. */
13479 tree
13481 MEM_STAT_DECL)
13482 {
13483 tree tem;
13484 #ifdef ENABLE_FOLD_CHECKING
13492 htab_t ht;
13509 #endif
13516 #ifdef ENABLE_FOLD_CHECKING
13540 #endif
13542 }
13544 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
13545 arguments in ARGARRAY, and a null static chain.
13546 Return a folded expression if successful. Otherwise, return a CALL_EXPR
13547 of type TYPE from the given operands as constructed by build_call_array. */
13549 tree
13551 {
13552 tree tem;
13553 #ifdef ENABLE_FOLD_CHECKING
13559 htab_t ht;
13573 #endif
13577 #ifdef ENABLE_FOLD_CHECKING
13594 #endif
13596 }
13598 /* Perform constant folding and related simplification of initializer
13599 expression EXPR. These behave identically to "fold_buildN" but ignore
13600 potential run-time traps and exceptions that fold must preserve. */
13602 #define START_FOLD_INIT \
13603 int saved_signaling_nans = flag_signaling_nans;\
13604 int saved_trapping_math = flag_trapping_math;\
13605 int saved_rounding_math = flag_rounding_math;\
13606 int saved_trapv = flag_trapv;\
13607 int saved_folding_initializer = folding_initializer;\
13608 flag_signaling_nans = 0;\
13609 flag_trapping_math = 0;\
13610 flag_rounding_math = 0;\
13611 flag_trapv = 0;\
13612 folding_initializer = 1;
13614 #define END_FOLD_INIT \
13615 flag_signaling_nans = saved_signaling_nans;\
13616 flag_trapping_math = saved_trapping_math;\
13617 flag_rounding_math = saved_rounding_math;\
13618 flag_trapv = saved_trapv;\
13619 folding_initializer = saved_folding_initializer;
13621 tree
13623 {
13624 tree result;
13625 START_FOLD_INIT;
13629 END_FOLD_INIT;
13631 }
13633 tree
13635 {
13636 tree result;
13637 START_FOLD_INIT;
13641 END_FOLD_INIT;
13643 }
13645 tree
13647 tree op2)
13648 {
13649 tree result;
13650 START_FOLD_INIT;
13654 END_FOLD_INIT;
13656 }
13658 tree
13661 {
13662 tree result;
13663 START_FOLD_INIT;
13667 END_FOLD_INIT;
13669 }
13671 #undef START_FOLD_INIT
13672 #undef END_FOLD_INIT
13674 /* Determine if first argument is a multiple of second argument. Return 0 if
13675 it is not, or we cannot easily determined it to be.
13677 An example of the sort of thing we care about (at this point; this routine
13678 could surely be made more general, and expanded to do what the *_DIV_EXPR's
13679 fold cases do now) is discovering that
13681 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13683 is a multiple of
13685 SAVE_EXPR (J * 8)
13687 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13689 This code also handles discovering that
13691 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13693 is a multiple of 8 so we don't have to worry about dealing with a
13694 possible remainder.
13696 Note that we *look* inside a SAVE_EXPR only to determine how it was
13697 calculated; it is not safe for fold to do much of anything else with the
13698 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13699 at run time. For example, the latter example above *cannot* be implemented
13700 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13701 evaluation time of the original SAVE_EXPR is not necessarily the same at
13702 the time the new expression is evaluated. The only optimization of this
13703 sort that would be valid is changing
13705 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13707 divided by 8 to
13709 SAVE_EXPR (I) * SAVE_EXPR (J)
13711 (where the same SAVE_EXPR (J) is used in the original and the
13712 transformed version). */
13714 int
13716 {
13724 {
13726 /* Bitwise and provides a power of two multiple. If the mask is
13727 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13730 /* FALLTHRU */
13743 {
13747 /* const_binop may not detect overflow correctly,
13748 so check for it explicitly here. */
13754 size_one_node,
13758 }
13762 /* Can't handle conversions from non-integral or wider integral type. */
13768 /* .. fall through ... */
13785 }
13786 }
13788 /* Return true if `t' is known to be non-negative. If the return
13789 value is based on the assumption that signed overflow is undefined,
13790 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13791 *STRICT_OVERFLOW_P. */
13793 bool
13795 {
13803 {
13805 /* Query VRP to see if it has recorded any information about
13806 the range of this object. */
13810 /* We can't return 1 if flag_wrapv is set because
13811 ABS_EXPR<INT_MIN> = INT_MIN. */
13815 {
13818 }
13834 strict_overflow_p)
13836 strict_overflow_p));
13838 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13839 both unsigned and at least 2 bits shorter than the result. */
13843 {
13848 {
13852 }
13853 }
13858 {
13859 /* x * x for floating point x is always non-negative. */
13863 strict_overflow_p)
13865 strict_overflow_p));
13866 }
13868 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13869 both unsigned and their total bits is shorter than the result. */
13873 {
13880 }
13886 strict_overflow_p)
13888 strict_overflow_p));
13899 strict_overflow_p)
13901 strict_overflow_p));
13912 strict_overflow_p);
13918 strict_overflow_p);
13922 strict_overflow_p);
13926 strict_overflow_p)
13928 strict_overflow_p));
13931 {
13936 {
13939 strict_overflow_p);
13941 {
13945 strict_overflow_p);
13946 }
13947 }
13949 {
13952 strict_overflow_p);
13956 }
13957 }
13961 {
13965 /* If the initializer is non-void, then it's a normal expression
13966 that will be assigned to the slot. */
13970 /* Otherwise, the initializer sets the slot in some way. One common
13971 way is an assignment statement at the end of the initializer. */
13973 {
13981 else
13983 }
13988 strict_overflow_p);
13991 }
13994 {
13998 {
14016 /* Always true. */
14020 /* sqrt(-0.0) is -0.0. */
14024 strict_overflow_p);
14057 /* True if the 1st argument is nonnegative. */
14059 strict_overflow_p);
14062 /* True if the 1st OR 2nd arguments are nonnegative. */
14064 strict_overflow_p)
14066 strict_overflow_p)));
14069 /* True if the 1st AND 2nd arguments are nonnegative. */
14071 strict_overflow_p)
14073 strict_overflow_p)));
14076 /* True if the 2nd argument is nonnegative. */
14078 strict_overflow_p);
14081 /* True if the 1st argument is nonnegative or the second
14082 argument is an even integer. */
14084 {
14088 }
14090 strict_overflow_p);
14093 /* True if the 1st argument is nonnegative or the second
14094 argument is an even integer valued real. */
14096 {
14097 REAL_VALUE_TYPE c;
14098 HOST_WIDE_INT n;
14103 {
14104 REAL_VALUE_TYPE cint;
14109 }
14110 }
14112 strict_overflow_p);
14116 }
14117 }
14119 /* ... fall through ... */
14122 {
14126 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14127 have a signed:1 type (where the value is -1 and 0). */
14129 }
14130 }
14132 /* We don't know sign of `t', so be conservative and return false. */
14134 }
14136 /* Return true if `t' is known to be non-negative. Handle warnings
14137 about undefined signed overflow. */
14139 bool
14141 {
14148 "determining that expression is always "
14150 WARN_STRICT_OVERFLOW_MISC);
14152 }
14154 /* Return true when T is an address and is known to be nonzero.
14155 For floating point we further ensure that T is not denormal.
14156 Similar logic is present in nonzero_address in rtlanal.h.
14158 If the return value is based on the assumption that signed overflow
14159 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14160 change *STRICT_OVERFLOW_P. */
14162 bool
14164 {
14168 /* Doing something useful for floating point would need more work. */
14173 {
14175 /* Query VRP to see if it has recorded any information about
14176 the range of this object. */
14181 strict_overflow_p);
14189 {
14190 /* With the presence of negative values it is hard
14191 to say something. */
14198 /* One of operands must be positive and the other non-negative. */
14199 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14200 overflows, on a twos-complement machine the sum of two
14201 nonnegative numbers can never be zero. */
14203 strict_overflow_p)
14205 strict_overflow_p));
14206 }
14211 {
14213 strict_overflow_p)
14215 strict_overflow_p))
14216 {
14219 }
14220 }
14224 {
14230 strict_overflow_p));
14231 }
14235 {
14241 /* Weak declarations may link to NULL. */
14245 /* Constants are never weak. */
14250 }
14258 {
14262 }
14271 {
14274 }
14281 {
14285 /* When both operands are nonzero, then MAX must be too. */
14287 strict_overflow_p))
14290 /* MAX where operand 0 is positive is positive. */
14292 strict_overflow_p);
14293 }
14294 /* MAX where operand 1 is positive is positive. */
14299 {
14303 }
14311 strict_overflow_p);
14316 strict_overflow_p);
14320 strict_overflow_p)
14322 strict_overflow_p));
14329 }
14331 }
14333 /* Return true when T is an address and is known to be nonzero.
14334 Handle warnings about undefined signed overflow. */
14336 bool
14338 {
14345 "determining that expression is always "
14347 WARN_STRICT_OVERFLOW_MISC);
14349 }
14351 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
14352 attempt to fold the expression to a constant without modifying TYPE,
14353 OP0 or OP1.
14355 If the expression could be simplified to a constant, then return
14356 the constant. If the expression would not be simplified to a
14357 constant, then return NULL_TREE. */
14359 tree
14361 {
14364 }
14366 /* Given the components of a unary expression CODE, TYPE and OP0,
14367 attempt to fold the expression to a constant without modifying
14368 TYPE or OP0.
14370 If the expression could be simplified to a constant, then return
14371 the constant. If the expression would not be simplified to a
14372 constant, then return NULL_TREE. */
14374 tree
14376 {
14379 }
14381 /* If EXP represents referencing an element in a constant string
14382 (either via pointer arithmetic or array indexing), return the
14383 tree representing the value accessed, otherwise return NULL. */
14385 tree
14387 {
14391 {
14393 tree index;
14394 tree string;
14398 else
14399 {
14403 /* Optimize the special-case of a zero lower bound.
14405 We convert the low_bound to sizetype to avoid some problems
14406 with constant folding. (E.g. suppose the lower bound is 1,
14407 and its mode is QI. Without the conversion,l (ARRAY
14408 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
14409 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
14414 }
14427 }
14429 }
14431 /* Return the tree for neg (ARG0) when ARG0 is known to be either
14432 an integer constant, real, or fixed-point constant.
14434 TYPE is the type of the result. */
14436 static tree
14438 {
14442 {
14444 {
14446 HOST_WIDE_INT high;
14454 }
14461 {
14462 FIXED_VALUE_TYPE f;
14467 /* Propagate overflow flags. */
14469 {
14472 }
14476 }
14480 }
14483 }
14485 /* Return the tree for abs (ARG0) when ARG0 is known to be either
14486 an integer constant or real constant.
14488 TYPE is the type of the result. */
14490 tree
14492 {
14496 {
14498 /* If the value is unsigned, then the absolute value is
14499 the same as the ordinary value. */
14502 /* Similarly, if the value is non-negative. */
14505 /* If the value is negative, then the absolute value is
14506 its negation. */
14507 else
14508 {
14510 HOST_WIDE_INT high;
14516 }
14522 else
14528 }
14531 }
14533 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
14534 constant. TYPE is the type of the result. */
14536 static tree
14538 {
14548 }
14550 /* Given CODE, a relational operator, the target type, TYPE and two
14551 constant operands OP0 and OP1, return the result of the
14552 relational operation. If the result is not a compile time
14553 constant, then return NULL_TREE. */
14555 static tree
14557 {
14560 /* From here on, the only cases we handle are when the result is
14561 known to be a constant. */
14564 {
14568 /* Handle the cases where either operand is a NaN. */
14570 {
14572 {
14600 }
14603 }
14606 }
14609 {
14613 }
14615 /* Handle equality/inequality of complex constants. */
14617 {
14628 else
14630 }
14632 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14634 To compute GT, swap the arguments and do LT.
14635 To compute GE, do LT and invert the result.
14636 To compute LE, swap the arguments, do LT and invert the result.
14637 To compute NE, do EQ and invert the result.
14639 Therefore, the code below must handle only EQ and LT. */
14642 {
14647 }
14649 /* Note that it is safe to invert for real values here because we
14650 have already handled the one case that it matters. */
14654 {
14657 }
14659 /* Compute a result for LT or EQ if args permit;
14660 Otherwise return T. */
14662 {
14667 else
14669 }
14670 else
14676 }
14678 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14679 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14680 itself. */
14682 tree
14684 {
14685 /* If the expression does not have side effects then we don't have to wrap
14686 it with a cleanup point expression. */
14690 /* If the expression is a return, check to see if the expression inside the
14691 return has no side effects or the right hand side of the modify expression
14692 inside the return. If either don't have side effects set we don't need to
14693 wrap the expression in a cleanup point expression. Note we don't check the
14694 left hand side of the modify because it should always be a return decl. */
14696 {
14703 }
14706 }
14708 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14709 of an indirection through OP0, or NULL_TREE if no simplification is
14710 possible. */
14712 tree
14714 {
14716 tree subtype;
14724 {
14727 /* *&CONST_DECL -> to the value of the const decl. */
14730 /* *&p => p; make sure to handle *&"str"[cst] here. */
14732 {
14736 else
14738 }
14739 /* *(foo *)&fooarray => fooarray[0] */
14742 {
14748 }
14749 /* *(foo *)&complexfoo => __real__ complexfoo */
14753 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14756 {
14760 }
14761 }
14763 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14766 {
14769 tree op00type;
14776 {
14780 }
14781 }
14783 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14786 {
14787 tree type_domain;
14794 }
14797 }
14799 /* Builds an expression for an indirection through T, simplifying some
14800 cases. */
14802 tree
14804 {
14810 else
14812 }
14814 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14816 tree
14818 {
14823 else
14825 }
14827 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14828 whose result is ignored. The type of the returned tree need not be
14829 the same as the original expression. */
14831 tree
14833 {
14839 {
14850 else
14856 {
14872 }
14877 }
14878 }
14880 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
14881 This can only be applied to objects of a sizetype. */
14883 tree
14885 {
14892 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14893 have to do anything. Only do this when we are not given a const,
14894 because in that case, this check is more expensive than just
14895 doing it. */
14897 {
14902 }
14904 /* If divisor is a power of two, simplify this to bit manipulation. */
14906 {
14908 {
14921 {
14922 high++;
14925 }
14929 }
14930 else
14931 {
14932 tree t;
14938 }
14939 }
14940 else
14941 {
14946 }
14949 }
14951 /* Likewise, but round down. */
14953 tree
14955 {
14962 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14963 have to do anything. Only do this when we are not given a const,
14964 because in that case, this check is more expensive than just
14965 doing it. */
14967 {
14972 }
14974 /* If divisor is a power of two, simplify this to bit manipulation. */
14976 {
14977 tree t;
14981 }
14982 else
14983 {
14988 }
14991 }
14993 /* Returns the pointer to the base of the object addressed by EXP and
14994 extracts the information about the offset of the access, storing it
14995 to PBITPOS and POFFSET. */
14997 static tree
15000 {
15001 tree core;
15004 HOST_WIDE_INT bitsize;
15007 {
15012 }
15013 else
15014 {
15018 }
15021 }
15023 /* Returns true if addresses of E1 and E2 differ by a constant, false
15024 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15026 bool
15028 {
15042 {
15052 }
15054 {
15055 /* If only one of the offsets is non-constant, the difference cannot
15056 be a constant. */
15058 }
15059 else
15064 }
15066 /* Simplify the floating point expression EXP when the sign of the
15067 result is not significant. Return NULL_TREE if no simplification
15068 is possible. */
15070 tree
15072 {
15076 {
15111 {
15114 {
15116 /* Strip copysign function call, return the 1st argument. */
15122 /* Strip sign ops from the argument of "odd" math functions. */
15124 {
15128 }
15130 }
15131 }
15136 }
15138 }