| blob | 66ea456693b2cfa86b6a8e69c802b27045c04f88 |
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, 2008, 2009
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. */
70 /* Nonzero if we are folding constants inside an initializer; zero
71 otherwise. */
74 /* The following constants represent a bit based encoding of GCC's
75 comparison operators. This encoding simplifies transformations
76 on relational comparison operators, such as AND and OR. */
94 };
127 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;
342 else
344 }
346 /* Negate a doubleword integer with doubleword result.
347 Return nonzero if the operation overflows, assuming it's signed.
348 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
349 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
351 int
354 {
356 {
360 }
361 else
362 {
366 }
367 }
368 \f
369 /* Multiply two doubleword integers with doubleword result.
370 Return nonzero if the operation overflows according to UNSIGNED_P.
371 Each argument is given as two `HOST_WIDE_INT' pieces.
372 One argument is L1 and H1; the other, L2 and H2.
373 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
375 int
380 {
395 {
398 {
400 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
402 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
406 }
408 }
413 /* Unsigned overflow is immediate. */
417 /* Check for signed overflow by calculating the signed representation of the
418 top half of the result; it should agree with the low half's sign bit. */
420 {
423 }
425 {
428 }
430 }
431 \f
432 /* Shift the doubleword integer in L1, H1 left by COUNT places
433 keeping only PREC bits of result.
434 Shift right if COUNT is negative.
435 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
436 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
438 void
442 {
446 {
449 }
455 {
456 /* Shifting by the host word size is undefined according to the
457 ANSI standard, so we must handle this as a special case. */
460 }
462 {
465 }
466 else
467 {
471 }
473 /* Sign extend all bits that are beyond the precision. */
481 ;
483 {
486 }
487 else
488 {
492 }
493 }
495 /* Shift the doubleword integer in L1, H1 right by COUNT places
496 keeping only PREC bits of result. COUNT must be positive.
497 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
498 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
500 void
505 {
508 signmask = (arith
516 {
517 /* Shifting by the host word size is undefined according to the
518 ANSI standard, so we must handle this as a special case. */
521 }
523 {
526 }
527 else
528 {
532 }
534 /* Zero / sign extend all bits that are beyond the precision. */
537 {
540 }
542 ;
544 {
547 }
548 else
549 {
553 }
554 }
555 \f
556 /* Rotate the doubleword integer in L1, H1 left by COUNT places
557 keeping only PREC bits of result.
558 Rotate right if COUNT is negative.
559 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
561 void
565 {
577 }
579 /* Rotate the doubleword integer in L1, H1 left by COUNT places
580 keeping only PREC bits of result. COUNT must be positive.
581 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
583 void
587 {
599 }
600 \f
601 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
602 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
603 CODE is a tree code for a kind of division, one of
604 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
605 or EXACT_DIV_EXPR
606 It controls how the quotient is rounded to an integer.
607 Return nonzero if the operation overflows.
608 UNS nonzero says do unsigned division. */
610 int
613 HOST_WIDE_INT hnum_orig,
615 HOST_WIDE_INT hden_orig,
619 {
635 /* Calculate quotient sign and convert operands to unsigned. */
637 {
639 {
641 /* (minimum integer) / (-1) is the only overflow case. */
645 }
647 {
650 }
651 }
656 /* This unsigned division rounds toward zero. */
659 }
663 /* hden != 0 already checked. */
668 }
678 /* Special code for when the divisor < BASE. */
680 {
681 /* hnum != 0 already checked. */
683 {
687 }
688 }
689 else
690 {
691 /* Full double precision division,
692 with thanks to Don Knuth's "Seminumerical Algorithms". */
696 /* Find the highest nonzero divisor digit. */
699 {
702 }
704 /* Insure that the first digit of the divisor is at least BASE/2.
705 This is required by the quotient digit estimation algorithm. */
712 {
716 }
721 {
726 }
727 }
731 /* Main loop */
733 {
734 /* Guess the next quotient digit, quo_est, by dividing the first
735 two remaining dividend digits by the high order quotient digit.
736 quo_est is never low and is at most 2 high. */
743 else
746 /* Refine quo_est so it's usually correct, and at most one high. */
751 quo_est--;
753 /* Try QUO_EST as the quotient digit, by multiplying the
754 divisor by QUO_EST and subtracting from the remaining dividend.
755 Keep in mind that QUO_EST is the I - 1st digit. */
759 {
765 }
767 /* If quo_est was high by one, then num[i] went negative and
768 we need to correct things. */
770 {
771 quo_est--;
774 {
778 }
781 }
783 /* Store the quotient digit. */
785 }
786 }
790 finish_up:
791 /* If result is negative, make it so. */
795 /* Compute trial remainder: rem = num - (quo * den) */
801 {
810 {
811 /* quo = quo - 1; */
814 }
815 else
822 {
825 }
826 else
832 {
838 /* Get absolute values. */
844 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
853 {
855 /* quo = quo - 1; */
858 else
859 /* quo = quo + 1; */
862 }
863 else
865 }
870 }
872 /* Compute true remainder: rem = num - (quo * den) */
877 }
879 /* If ARG2 divides ARG1 with zero remainder, carries out the division
880 of type CODE and returns the quotient.
881 Otherwise returns NULL_TREE. */
883 static tree
885 {
895 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
896 &obj[some_exotic_number]. */
898 {
902 type);
903 }
904 else
915 }
916 \f
917 /* This is nonzero if we should defer warnings about undefined
918 overflow. This facility exists because these warnings are a
919 special case. The code to estimate loop iterations does not want
920 to issue any warnings, since it works with expressions which do not
921 occur in user code. Various bits of cleanup code call fold(), but
922 only use the result if it has certain characteristics (e.g., is a
923 constant); that code only wants to issue a warning if the result is
924 used. */
928 /* If a warning about undefined overflow is deferred, this is the
929 warning. Note that this may cause us to turn two warnings into
930 one, but that is fine since it is sufficient to only give one
931 warning per expression. */
935 /* If a warning about undefined overflow is deferred, this is the
936 level at which the warning should be emitted. */
940 /* Start deferring overflow warnings. We could use a stack here to
941 permit nested calls, but at present it is not necessary. */
943 void
945 {
947 }
949 /* Stop deferring overflow warnings. If there is a pending warning,
950 and ISSUE is true, then issue the warning if appropriate. STMT is
951 the statement with which the warning should be associated (used for
952 location information); STMT may be NULL. CODE is the level of the
953 warning--a warn_strict_overflow_code value. This function will use
954 the smaller of CODE and the deferred code when deciding whether to
955 issue the warning. CODE may be zero to mean to always use the
956 deferred code. */
958 void
960 {
962 location_t locus;
967 {
973 }
984 /* Use the smallest code level when deciding to issue the
985 warning. */
994 else
997 }
999 /* Stop deferring overflow warnings, ignoring any deferred
1000 warnings. */
1002 void
1004 {
1006 }
1008 /* Whether we are deferring overflow warnings. */
1010 bool
1012 {
1014 }
1016 /* This is called when we fold something based on the fact that signed
1017 overflow is undefined. */
1019 static void
1021 {
1023 {
1026 {
1029 }
1030 }
1033 }
1034 \f
1035 /* Return true if the built-in mathematical function specified by CODE
1036 is odd, i.e. -f(x) == f(-x). */
1038 static bool
1040 {
1042 {
1076 }
1078 }
1080 /* Check whether we may negate an integer constant T without causing
1081 overflow. */
1083 bool
1085 {
1088 tree type;
1098 {
1103 }
1104 else
1109 }
1111 /* Determine whether an expression T can be cheaply negated using
1112 the function negate_expr without introducing undefined overflow. */
1114 static bool
1116 {
1117 tree type;
1126 {
1157 /* -(A + B) -> (-B) - A. */
1162 /* -(A + B) -> (-A) - B. */
1167 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1178 /* Fall through. */
1191 /* In general we can't negate A / B, because if A is INT_MIN and
1192 B is 1, we may turn this into INT_MIN / -1 which is undefined
1193 and actually traps on some architectures. */
1199 CASE_CONVERT:
1200 /* Negate -((double)float) as (double)(-float). */
1202 {
1206 }
1210 /* Negate -f(x) as f(-x). */
1216 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1218 {
1224 }
1229 }
1231 }
1233 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1234 simplification is possible.
1235 If negate_expr_p would return true for T, NULL_TREE will never be
1236 returned. */
1238 static tree
1240 {
1242 tree tem;
1245 {
1246 /* Convert - (~A) to A + 1. */
1262 /* Two's complement FP formats, such as c4x, may overflow. */
1272 {
1281 }
1305 {
1306 /* -(A + B) -> (-B) - A. */
1310 {
1314 }
1316 /* -(A + B) -> (-A) - B. */
1318 {
1322 }
1323 }
1328 /* - (A - B) -> B - A */
1341 /* Fall through. */
1345 {
1354 }
1362 /* In general we can't negate A / B, because if A is INT_MIN and
1363 B is 1, we may turn this into INT_MIN / -1 which is undefined
1364 and actually traps on some architectures. */
1366 {
1375 }
1378 CASE_CONVERT:
1379 /* Convert -((double)float) into (double)(-float). */
1381 {
1385 }
1389 /* Negate -f(x) as f(-x). */
1392 {
1398 }
1402 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1404 {
1409 {
1416 }
1417 }
1422 }
1425 }
1427 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1428 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1429 return NULL_TREE. */
1431 static tree
1433 {
1446 }
1447 \f
1448 /* Split a tree IN into a constant, literal and variable parts that could be
1449 combined with CODE to make IN. "constant" means an expression with
1450 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1451 commutative arithmetic operation. Store the constant part into *CONP,
1452 the literal in *LITP and return the variable part. If a part isn't
1453 present, set it to null. If the tree does not decompose in this way,
1454 return the entire tree as the variable part and the other parts as null.
1456 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1457 case, we negate an operand that was subtracted. Except if it is a
1458 literal for which we use *MINUS_LITP instead.
1460 If NEGATE_P is true, we are negating all of IN, again except a literal
1461 for which we use *MINUS_LITP instead.
1463 If IN is itself a literal or constant, return it as appropriate.
1465 Note that we do not guarantee that any of the three values will be the
1466 same type as IN, but they will have the same signedness and mode. */
1468 static tree
1471 {
1478 /* Strip any conversions that don't change the machine mode or signedness. */
1487 /* We can associate addition and subtraction together (even
1488 though the C standard doesn't say so) for integers because
1489 the value is not affected. For reals, the value might be
1490 affected, so we can't. */
1493 {
1499 /* First see if either of the operands is a literal, then a constant. */
1512 /* If we haven't dealt with either operand, this is not a case we can
1513 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1518 else
1521 /* Now do any needed negations. */
1528 }
1531 else
1535 {
1542 }
1545 }
1547 /* Re-associate trees split by the above function. T1 and T2 are either
1548 expressions to associate or null. Return the new expression, if any. If
1549 we build an operation, do it in TYPE and with CODE. */
1551 static tree
1553 {
1559 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1560 try to fold this since we will have infinite recursion. But do
1561 deal with any NEGATE_EXPRs. */
1565 {
1567 {
1576 }
1578 {
1581 }
1585 }
1589 }
1590 \f
1591 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1592 for use in int_const_binop, size_binop and size_diffop. */
1594 static bool
1596 {
1603 {
1612 }
1617 }
1620 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1621 to produce a new constant in *LOWP, *HIP. Return -1 if we don't know how
1622 to evaluate CODE at compile-time otherwise return 1 if the
1623 operation overflowed and 0 if not. */
1625 int
1628 {
1632 HOST_WIDE_INT hi;
1634 HOST_WIDE_INT garbageh;
1645 {
1661 /* It's unclear from the C standard whether shifts can overflow.
1662 The following code ignores overflow; perhaps a C standard
1663 interpretation ruling is needed. */
1689 else
1702 /* This is a shortcut for a common special case. */
1707 {
1713 }
1715 /* ... fall through ... */
1721 {
1724 }
1727 {
1730 }
1737 /* This is a shortcut for a common special case. */
1742 {
1747 }
1749 /* ... fall through ... */
1767 else
1773 else
1779 }
1785 }
1787 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1788 to produce a new constant. Return NULL_TREE if we don't know how
1789 to evaluate CODE at compile-time.
1791 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1793 tree
1796 {
1798 HOST_WIDE_INT hi;
1799 tree t;
1802 int is_sizetype
1811 {
1814 /* Propagate overflow flags ourselves. */
1817 {
1820 }
1821 }
1822 else
1828 }
1830 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1831 constant. We assume ARG1 and ARG2 have the same data type, or at least
1832 are the same kind of constant and the same machine mode. Return zero if
1833 combining the constants is not allowed in the current operating mode.
1835 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1837 static tree
1839 {
1840 /* Sanity check for the recursive cases. */
1851 {
1853 REAL_VALUE_TYPE d1;
1854 REAL_VALUE_TYPE d2;
1855 REAL_VALUE_TYPE value;
1856 REAL_VALUE_TYPE result;
1860 /* The following codes are handled by real_arithmetic. */
1862 {
1873 }
1881 /* Don't perform operation if we honor signaling NaNs and
1882 either operand is a NaN. */
1887 /* Don't perform operation if it would raise a division
1888 by zero exception. */
1894 /* If either operand is a NaN, just return it. Otherwise, set up
1895 for floating-point trap; we return an overflow. */
1904 /* Don't constant fold this floating point operation if
1905 the result has overflowed and flag_trapping_math. */
1913 /* Don't constant fold this floating point operation if the
1914 result may dependent upon the run-time rounding mode and
1915 flag_rounding_math is set, or if GCC's software emulation
1916 is unable to accurately represent the result. */
1926 }
1929 {
1930 FIXED_VALUE_TYPE f1;
1931 FIXED_VALUE_TYPE f2;
1932 FIXED_VALUE_TYPE result;
1937 /* The following codes are handled by fixed_arithmetic. */
1939 {
1956 }
1963 /* Propagate overflow flags. */
1965 {
1968 }
1972 }
1975 {
1984 {
1995 notrunc);
1999 notrunc);
2003 {
2004 tree magsquared
2008 notrunc);
2009 tree t1
2013 notrunc);
2014 tree t2
2018 notrunc);
2025 }
2030 }
2034 }
2037 }
2039 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2040 indicates which particular sizetype to create. */
2042 tree
2044 {
2046 }
2047 \f
2048 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2049 is a tree code. The type of the result is taken from the operands.
2050 Both must be equivalent integer types, ala int_binop_types_match_p.
2051 If the operands are constant, so is the result. */
2053 tree
2055 {
2064 /* Handle the special case of two integer constants faster. */
2066 {
2067 /* And some specific cases even faster than that. */
2069 {
2074 }
2076 {
2079 }
2081 {
2084 }
2086 /* Handle general case of two integer constants. */
2088 }
2091 }
2093 /* Given two values, either both of sizetype or both of bitsizetype,
2094 compute the difference between the two values. Return the value
2095 in signed type corresponding to the type of the operands. */
2097 tree
2099 {
2101 tree ctype;
2106 /* If the type is already signed, just do the simple thing. */
2114 else
2117 /* If either operand is not a constant, do the conversions to the signed
2118 type and subtract. The hardware will do the right thing with any
2119 overflow in the subtraction. */
2124 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2125 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2126 overflow) and negate (which can't either). Special-case a result
2127 of zero while we're here. */
2132 else
2136 }
2137 \f
2138 /* A subroutine of fold_convert_const handling conversions of an
2139 INTEGER_CST to another integer type. */
2141 static tree
2143 {
2144 tree t;
2146 /* Given an integer constant, make new constant with new type,
2147 appropriately sign-extended or truncated. */
2150 /* Don't set the overflow when
2151 converting from a pointer, */
2153 /* or to a sizetype with same signedness
2154 and the precision is unchanged.
2155 ??? sizetype is always sign-extended,
2156 but its signedness depends on the
2157 frontend. Thus we see spurious overflows
2158 here if we do not check this. */
2173 }
2175 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2176 to an integer type. */
2178 static tree
2180 {
2182 tree t;
2184 /* The following code implements the floating point to integer
2185 conversion rules required by the Java Language Specification,
2186 that IEEE NaNs are mapped to zero and values that overflow
2187 the target precision saturate, i.e. values greater than
2188 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2189 are mapped to INT_MIN. These semantics are allowed by the
2190 C and C++ standards that simply state that the behavior of
2191 FP-to-integer conversion is unspecified upon overflow. */
2194 REAL_VALUE_TYPE r;
2198 {
2205 }
2207 /* If R is NaN, return zero and show we have an overflow. */
2209 {
2213 }
2215 /* See if R is less than the lower bound or greater than the
2216 upper bound. */
2219 {
2223 {
2227 }
2228 }
2231 {
2234 {
2237 {
2241 }
2242 }
2243 }
2251 }
2253 /* A subroutine of fold_convert_const handling conversions of a
2254 FIXED_CST to an integer type. */
2256 static tree
2258 {
2259 tree t;
2263 /* Right shift FIXED_CST to temp by fbit. */
2267 {
2272 /* Left shift temp to temp_trunc by fbit. */
2277 }
2278 else
2279 {
2284 }
2286 /* If FIXED_CST is negative, we need to round the value toward 0.
2287 By checking if the fractional bits are not zero to add 1 to temp. */
2290 {
2291 double_int one;
2295 }
2297 /* Given a fixed-point constant, make new constant with new type,
2298 appropriately sign-extended or truncated. */
2306 }
2308 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2309 to another floating point type. */
2311 static tree
2313 {
2314 REAL_VALUE_TYPE value;
2315 tree t;
2322 }
2324 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2325 to a floating point type. */
2327 static tree
2329 {
2330 REAL_VALUE_TYPE value;
2331 tree t;
2340 }
2342 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2343 to another fixed-point type. */
2345 static tree
2347 {
2348 FIXED_VALUE_TYPE value;
2349 tree t;
2356 /* Propagate overflow flags. */
2358 {
2361 }
2365 }
2367 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2368 to a fixed-point type. */
2370 static tree
2372 {
2373 FIXED_VALUE_TYPE value;
2374 tree t;
2383 /* Propagate overflow flags. */
2385 {
2388 }
2392 }
2394 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2395 to a fixed-point type. */
2397 static tree
2399 {
2400 FIXED_VALUE_TYPE value;
2401 tree t;
2409 /* Propagate overflow flags. */
2411 {
2414 }
2418 }
2420 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2421 type TYPE. If no simplification can be done return NULL_TREE. */
2423 static tree
2425 {
2431 {
2438 }
2440 {
2447 }
2449 {
2456 }
2458 }
2460 /* Construct a vector of zero elements of vector type TYPE. */
2462 static tree
2464 {
2475 }
2477 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2479 bool
2481 {
2496 {
2515 }
2516 }
2518 /* Convert expression ARG to type TYPE. Used by the middle-end for
2519 simple conversions in preference to calling the front-end's convert. */
2521 tree
2523 {
2525 tree tem;
2539 {
2544 {
2548 }
2553 {
2556 }
2563 {
2567 }
2569 {
2573 }
2575 {
2579 }
2582 {
2600 }
2605 {
2609 }
2612 {
2626 }
2630 {
2640 {
2644 {
2648 }
2656 }
2660 }
2678 }
2679 }
2680 \f
2681 /* Return false if expr can be assumed not to be an lvalue, true
2682 otherwise. */
2684 static bool
2686 {
2687 /* We only need to wrap lvalue tree codes. */
2689 {
2723 /* Assume the worst for front-end tree codes. */
2727 }
2730 }
2732 /* Return an expr equal to X but certainly not valid as an lvalue. */
2734 tree
2736 {
2737 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2738 us. */
2745 }
2747 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2748 Zero means allow extended lvalues. */
2752 /* When pedantic, return an expr equal to X but certainly not valid as a
2753 pedantic lvalue. Otherwise, return X. */
2755 static tree
2757 {
2760 else
2762 }
2763 \f
2764 /* Given a tree comparison code, return the code that is the logical inverse
2765 of the given code. It is not safe to do this for floating-point
2766 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2767 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2769 enum tree_code
2771 {
2776 {
2807 }
2808 }
2810 /* Similar, but return the comparison that results if the operands are
2811 swapped. This is safe for floating-point. */
2813 enum tree_code
2815 {
2817 {
2843 }
2844 }
2847 /* Convert a comparison tree code from an enum tree_code representation
2848 into a compcode bit-based encoding. This function is the inverse of
2849 compcode_to_comparison. */
2851 static enum comparison_code
2853 {
2855 {
2886 }
2887 }
2889 /* Convert a compcode bit-based encoding of a comparison operator back
2890 to GCC's enum tree_code representation. This function is the
2891 inverse of comparison_to_compcode. */
2893 static enum tree_code
2895 {
2897 {
2928 }
2929 }
2931 /* Return a tree for the comparison which is the combination of
2932 doing the AND or OR (depending on CODE) of the two operations LCODE
2933 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2934 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2935 if this makes the transformation invalid. */
2937 tree
2941 {
2948 {
2959 }
2962 {
2963 /* Eliminate unordered comparisons, as well as LTGT and ORD
2964 which are not used unless the mode has NaNs. */
2970 }
2972 {
2973 /* Check that the original operation and the optimized ones will trap
2974 under the same condition. */
2985 /* In a short-circuited boolean expression the LHS might be
2986 such that the RHS, if evaluated, will never trap. For
2987 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2988 if neither x nor y is NaN. (This is a mixed blessing: for
2989 example, the expression above will never trap, hence
2990 optimizing it to x < y would be invalid). */
2995 /* If the comparison was short-circuited, and only the RHS
2996 trapped, we may now generate a spurious trap. */
3001 /* If we changed the conditions that cause a trap, we lose. */
3004 }
3010 else
3013 }
3014 \f
3015 /* Return nonzero if two operands (typically of the same tree node)
3016 are necessarily equal. If either argument has side-effects this
3017 function returns zero. FLAGS modifies behavior as follows:
3019 If OEP_ONLY_CONST is set, only return nonzero for constants.
3020 This function tests whether the operands are indistinguishable;
3021 it does not test whether they are equal using C's == operation.
3022 The distinction is important for IEEE floating point, because
3023 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3024 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3026 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3027 even though it may hold multiple values during a function.
3028 This is because a GCC tree node guarantees that nothing else is
3029 executed between the evaluation of its "operands" (which may often
3030 be evaluated in arbitrary order). Hence if the operands themselves
3031 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3032 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3033 unset means assuming isochronic (or instantaneous) tree equivalence.
3034 Unless comparing arbitrary expression trees, such as from different
3035 statements, this flag can usually be left unset.
3037 If OEP_PURE_SAME is set, then pure functions with identical arguments
3038 are considered the same. It is used when the caller has other ways
3039 to ensure that global memory is unchanged in between. */
3041 int
3043 {
3044 /* If either is ERROR_MARK, they aren't equal. */
3048 /* Check equality of integer constants before bailing out due to
3049 precision differences. */
3053 /* If both types don't have the same signedness, then we can't consider
3054 them equal. We must check this before the STRIP_NOPS calls
3055 because they may change the signedness of the arguments. As pointers
3056 strictly don't have a signedness, require either two pointers or
3057 two non-pointers as well. */
3062 /* If both types don't have the same precision, then it is not safe
3063 to strip NOPs. */
3070 /* In case both args are comparisons but with different comparison
3071 code, try to swap the comparison operands of one arg to produce
3072 a match and compare that variant. */
3076 {
3084 }
3087 /* This is needed for conversions and for COMPONENT_REF.
3088 Might as well play it safe and always test this. */
3094 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3095 We don't care about side effects in that case because the SAVE_EXPR
3096 takes care of that for us. In all other cases, two expressions are
3097 equal if they have no side effects. If we have two identical
3098 expressions with side effects that should be treated the same due
3099 to the only side effects being identical SAVE_EXPR's, that will
3100 be detected in the recursive calls below. */
3106 /* Next handle constant cases, those for which we can return 1 even
3107 if ONLY_CONST is set. */
3110 {
3125 {
3126 /* If we do not distinguish between signed and unsigned zero,
3127 consider them equal. */
3130 }
3134 {
3140 {
3142 flags))
3146 }
3149 }
3153 flags)
3155 flags));
3168 }
3173 /* Define macros to test an operand from arg0 and arg1 for equality and a
3174 variant that allows null and views null as being different from any
3175 non-null value. In the latter case, if either is null, the both
3176 must be; otherwise, do the normal comparison. */
3177 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3178 TREE_OPERAND (arg1, N), flags)
3180 #define OP_SAME_WITH_NULL(N) \
3181 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3182 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3185 {
3187 /* Two conversions are equal only if signedness and modes match. */
3189 {
3190 CASE_CONVERT:
3198 }
3208 /* For commutative ops, allow the other order. */
3216 /* If either of the pointer (or reference) expressions we are
3217 dereferencing contain a side effect, these cannot be equal. */
3223 {
3233 /* Operands 2 and 3 may be null.
3234 Compare the array index by value if it is constant first as we
3235 may have different types but same value here. */
3244 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3245 may be NULL when we're called to compare MEM_EXPRs. */
3255 }
3259 {
3274 /* Otherwise take into account this is a commutative operation. */
3285 }
3289 {
3291 /* If the CALL_EXPRs call different functions, then they
3292 clearly can not be equal. */
3294 flags))
3297 {
3301 else
3305 }
3307 /* Now see if all the arguments are the same. */
3308 {
3319 /* If we get here and both argument lists are exhausted
3320 then the CALL_EXPRs are equal. */
3322 }
3325 }
3328 /* Consider __builtin_sqrt equal to sqrt. */
3336 }
3338 #undef OP_SAME
3339 #undef OP_SAME_WITH_NULL
3340 }
3341 \f
3342 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3343 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3345 When in doubt, return 0. */
3347 static int
3349 {
3361 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3362 and see if the inner values are the same. This removes any
3363 signedness comparison, which doesn't matter here. */
3370 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3371 actual comparison operand, ARG0.
3373 First throw away any conversions to wider types
3374 already present in the operands. */
3383 {
3386 /* Make sure shorter operand is extended the right way
3387 to match the longer operand. */
3393 }
3396 }
3397 \f
3398 /* See if ARG is an expression that is either a comparison or is performing
3399 arithmetic on comparisons. The comparisons must only be comparing
3400 two different values, which will be stored in *CVAL1 and *CVAL2; if
3401 they are nonzero it means that some operands have already been found.
3402 No variables may be used anywhere else in the expression except in the
3403 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3404 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3406 If this is true, return 1. Otherwise, return zero. */
3408 static int
3410 {
3414 /* We can handle some of the tcc_expression cases here. */
3424 {
3425 /* If we've already found a CVAL1 or CVAL2, this expression is
3426 two complex to handle. */
3432 }
3435 {
3458 /* First see if we can handle the first operand, then the second. For
3459 the second operand, we know *CVAL1 can't be zero. It must be that
3460 one side of the comparison is each of the values; test for the
3461 case where this isn't true by failing if the two operands
3462 are the same. */
3471 ;
3475 ;
3476 else
3480 ;
3484 ;
3485 else
3492 }
3493 }
3494 \f
3495 /* ARG is a tree that is known to contain just arithmetic operations and
3496 comparisons. Evaluate the operations in the tree substituting NEW0 for
3497 any occurrence of OLD0 as an operand of a comparison and likewise for
3498 NEW1 and OLD1. */
3500 static tree
3502 {
3507 /* We can handle some of the tcc_expression cases here. */
3515 {
3530 {
3547 }
3548 /* Fall through - ??? */
3551 {
3555 /* We need to check both for exact equality and tree equality. The
3556 former will be true if the operand has a side-effect. In that
3557 case, we know the operand occurred exactly once. */
3570 }
3574 }
3575 }
3576 \f
3577 /* Return a tree for the case when the result of an expression is RESULT
3578 converted to TYPE and OMITTED was previously an operand of the expression
3579 but is now not needed (e.g., we folded OMITTED * 0).
3581 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3582 the conversion of RESULT to TYPE. */
3584 tree
3586 {
3589 /* If the resulting operand is an empty statement, just return the omitted
3590 statement casted to void. */
3598 }
3600 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3602 static tree
3604 {
3607 /* If the resulting operand is an empty statement, just return the omitted
3608 statement casted to void. */
3616 }
3618 /* Return a tree for the case when the result of an expression is RESULT
3619 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3620 of the expression but are now not needed.
3622 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3623 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3624 evaluated before OMITTED2. Otherwise, if neither has side effects,
3625 just do the conversion of RESULT to TYPE. */
3627 tree
3629 {
3638 }
3640 \f
3641 /* Return a simplified tree node for the truth-negation of ARG. This
3642 never alters ARG itself. We assume that ARG is an operation that
3643 returns a truth value (0 or 1).
3645 FIXME: one would think we would fold the result, but it causes
3646 problems with the dominator optimizer. */
3648 tree
3650 {
3654 /* If this is a comparison, we can simply invert it, except for
3655 floating-point non-equality comparisons, in which case we just
3656 enclose a TRUTH_NOT_EXPR around what we have. */
3659 {
3662 && flag_trapping_math
3666 else
3667 {
3672 else
3675 }
3676 }
3679 {
3694 /* Here we can invert either operand. We invert the first operand
3695 unless the second operand is a TRUTH_NOT_EXPR in which case our
3696 result is the XOR of the first operand with the inside of the
3697 negation of the second operand. */
3702 else
3721 {
3724 /* A COND_EXPR may have a throw as one operand, which
3725 then has void type. Just leave void operands
3726 as they are. */
3732 }
3765 }
3768 }
3770 /* Return a simplified tree node for the truth-negation of ARG. This
3771 never alters ARG itself. We assume that ARG is an operation that
3772 returns a truth value (0 or 1).
3774 FIXME: one would think we would fold the result, but it causes
3775 problems with the dominator optimizer. */
3777 tree
3779 {
3780 tree tem;
3790 }
3792 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3793 operands are another bit-wise operation with a common input. If so,
3794 distribute the bit operations to save an operation and possibly two if
3795 constants are involved. For example, convert
3796 (A | B) & (A | C) into A | (B & C)
3797 Further simplification will occur if B and C are constants.
3799 If this optimization cannot be done, 0 will be returned. */
3801 static tree
3803 {
3804 tree common;
3814 {
3818 }
3820 {
3824 }
3826 {
3830 }
3832 {
3836 }
3837 else
3845 }
3847 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3848 with code CODE. This optimization is unsafe. */
3849 static tree
3851 {
3855 /* (A / C) +- (B / C) -> (A +- B) / C. */
3865 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3870 {
3882 }
3885 }
3886 \f
3887 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3888 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3890 static tree
3893 {
3897 {
3904 }
3918 }
3920 /* Optimize a bit-field compare.
3922 There are two cases: First is a compare against a constant and the
3923 second is a comparison of two items where the fields are at the same
3924 bit position relative to the start of a chunk (byte, halfword, word)
3925 large enough to contain it. In these cases we can avoid the shift
3926 implicit in bitfield extractions.
3928 For constants, we emit a compare of the shifted constant with the
3929 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3930 compared. For two fields at the same position, we do the ANDs with the
3931 similar mask and compare the result of the ANDs.
3933 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3934 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3935 are the left and right operands of the comparison, respectively.
3937 If the optimization described above can be done, we return the resulting
3938 tree. Otherwise we return zero. */
3940 static tree
3943 {
3952 tree mask;
3953 tree offset;
3955 /* Get all the information about the extractions being done. If the bit size
3956 if the same as the size of the underlying object, we aren't doing an
3957 extraction at all and so can do nothing. We also don't want to
3958 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3959 then will no longer be able to replace it. */
3967 {
3968 /* If this is not a constant, we can only do something if bit positions,
3969 sizes, and signedness are the same. */
3977 }
3979 /* See if we can find a mode to refer to this field. We should be able to,
3980 but fail if we can't. */
3989 /* Set signed and unsigned types of the precision of this mode for the
3990 shifts below. */
3994 /* Compute the bit position and size for the new reference and our offset
3995 within it. If the new reference is the same size as the original, we
3996 won't optimize anything, so return zero. */
4006 /* Make the mask to be used against the extracted field. */
4013 /* If not comparing with constant, just rework the comparison
4014 and return. */
4018 unsigned_type,
4021 mask),
4024 unsigned_type,
4027 mask));
4029 /* Otherwise, we are handling the constant case. See if the constant is too
4030 big for the field. Warn and return a tree of for 0 (false) if so. We do
4031 this not only for its own sake, but to avoid having to test for this
4032 error case below. If we didn't, we might generate wrong code.
4034 For unsigned fields, the constant shifted right by the field length should
4035 be all zero. For signed fields, the high-order bits should agree with
4036 the sign bit. */
4039 {
4043 {
4047 }
4048 }
4049 else
4050 {
4054 {
4058 }
4059 }
4061 /* Single-bit compares should always be against zero. */
4063 {
4066 }
4068 /* Make a new bitfield reference, shift the constant over the
4069 appropriate number of bits and mask it with the computed mask
4070 (in case this was a signed field). If we changed it, make a new one. */
4073 {
4076 }
4086 rhs);
4087 }
4088 \f
4089 /* Subroutine for fold_truthop: decode a field reference.
4091 If EXP is a comparison reference, we return the innermost reference.
4093 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4094 set to the starting bit number.
4096 If the innermost field can be completely contained in a mode-sized
4097 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4099 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4100 otherwise it is not changed.
4102 *PUNSIGNEDP is set to the signedness of the field.
4104 *PMASK is set to the mask used. This is either contained in a
4105 BIT_AND_EXPR or derived from the width of the field.
4107 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4109 Return 0 if this is not a component reference or is one that we can't
4110 do anything with. */
4112 static tree
4117 {
4121 tree unsigned_type;
4124 /* All the optimizations using this function assume integer fields.
4125 There are problems with FP fields since the type_for_size call
4126 below can fail for, e.g., XFmode. */
4130 /* We are interested in the bare arrangement of bits, so strip everything
4131 that doesn't affect the machine mode. However, record the type of the
4132 outermost expression if it may matter below. */
4139 {
4145 }
4154 /* If the number of bits in the reference is the same as the bitsize of
4155 the outer type, then the outer type gives the signedness. Otherwise
4156 (in case of a small bitfield) the signedness is unchanged. */
4160 /* Compute the mask to access the bitfield. */
4169 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4177 }
4179 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4180 bit positions. */
4182 static int
4184 {
4187 tree tmask;
4191 return
4198 }
4200 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4201 represents the sign bit of EXP's type. If EXP represents a sign
4202 or zero extension, also test VAL against the unextended type.
4203 The return value is the (sub)expression whose sign bit is VAL,
4204 or NULL_TREE otherwise. */
4206 static tree
4208 {
4212 tree t;
4214 /* Tree EXP must have an integral type. */
4219 /* Tree VAL must be an integer constant. */
4226 {
4233 }
4234 else
4235 {
4242 }
4244 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4245 treat VAL as if it were unsigned. */
4250 /* Handle extension from a narrower type. */
4256 }
4258 /* Subroutine for fold_truthop: determine if an operand is simple enough
4259 to be evaluated unconditionally. */
4261 static int
4263 {
4264 /* Strip any conversions that don't change the machine mode. */
4273 /* Don't regard global variables as simple. They may be
4274 allocated in ways unknown to the compiler (shared memory,
4275 #pragma weak, etc). */
4278 /* Loading a static variable is unduly expensive, but global
4279 registers aren't expensive. */
4281 }
4282 \f
4283 /* The following functions are subroutines to fold_range_test and allow it to
4284 try to change a logical combination of comparisons into a range test.
4286 For example, both
4287 X == 2 || X == 3 || X == 4 || X == 5
4288 and
4289 X >= 2 && X <= 5
4290 are converted to
4291 (unsigned) (X - 2) <= 3
4293 We describe each set of comparisons as being either inside or outside
4294 a range, using a variable named like IN_P, and then describe the
4295 range with a lower and upper bound. If one of the bounds is omitted,
4296 it represents either the highest or lowest value of the type.
4298 In the comments below, we represent a range by two numbers in brackets
4299 preceded by a "+" to designate being inside that range, or a "-" to
4300 designate being outside that range, so the condition can be inverted by
4301 flipping the prefix. An omitted bound is represented by a "-". For
4302 example, "- [-, 10]" means being outside the range starting at the lowest
4303 possible value and ending at 10, in other words, being greater than 10.
4304 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4305 always false.
4307 We set up things so that the missing bounds are handled in a consistent
4308 manner so neither a missing bound nor "true" and "false" need to be
4309 handled using a special case. */
4311 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4312 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4313 and UPPER1_P are nonzero if the respective argument is an upper bound
4314 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4315 must be specified for a comparison. ARG1 will be converted to ARG0's
4316 type if both are specified. */
4318 static tree
4321 {
4322 tree tem;
4326 /* If neither arg represents infinity, do the normal operation.
4327 Else, if not a comparison, return infinity. Else handle the special
4328 comparison rules. Note that most of the cases below won't occur, but
4329 are handled for consistency. */
4332 {
4337 }
4342 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4343 for neither. In real maths, we cannot assume open ended ranges are
4344 the same. But, this is computer arithmetic, where numbers are finite.
4345 We can therefore make the transformation of any unbounded range with
4346 the value Z, Z being greater than any representable number. This permits
4347 us to treat unbounded ranges as equal. */
4351 {
4372 }
4375 }
4376 \f
4377 /* Given EXP, a logical expression, set the range it is testing into
4378 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4379 actually being tested. *PLOW and *PHIGH will be made of the same
4380 type as the returned expression. If EXP is not a comparison, we
4381 will most likely not be returning a useful value and range. Set
4382 *STRICT_OVERFLOW_P to true if the return value is only valid
4383 because signed overflow is undefined; otherwise, do not change
4384 *STRICT_OVERFLOW_P. */
4386 static tree
4389 {
4396 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4397 and see if we can refine the range. Some of the cases below may not
4398 happen, but it doesn't seem worth worrying about this. We "continue"
4399 the outer loop when we've changed something; otherwise we "break"
4400 the switch, which will "break" the while. */
4406 {
4411 {
4423 }
4426 {
4433 /* We can only do something if the range is testing for zero
4434 and if the second operand is an integer constant. Note that
4435 saying something is "in" the range we make is done by
4436 complementing IN_P since it will set in the initial case of
4437 being not equal to zero; "out" is leaving it alone. */
4444 {
4465 }
4467 /* If this is an unsigned comparison, we also know that EXP is
4468 greater than or equal to zero. We base the range tests we make
4469 on that fact, so we record it here so we can parse existing
4470 range tests. We test arg0_type since often the return type
4471 of, e.g. EQ_EXPR, is boolean. */
4473 {
4477 NULL_TREE))
4482 /* If the high bound is missing, but we have a nonzero low
4483 bound, reverse the range so it goes from zero to the low bound
4484 minus 1. */
4486 {
4491 }
4492 }
4498 /* (-x) IN [a,b] -> x in [-b, -a] */
4510 /* ~ X -> -X - 1 */
4519 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4520 move a constant to the other side. */
4525 /* If EXP is signed, any overflow in the computation is undefined,
4526 so we don't worry about it so long as our computations on
4527 the bounds don't overflow. For unsigned, overflow is defined
4528 and this is exactly the right thing. */
4540 /* Check for an unsigned range which has wrapped around the maximum
4541 value thus making n_high < n_low, and normalize it. */
4543 {
4549 /* If the range is of the form +/- [ x+1, x ], we won't
4550 be able to normalize it. But then, it represents the
4551 whole range or the empty set, so make it
4552 +/- [ -, - ]. */
4556 else
4558 }
4559 else
4583 /* If we're converting arg0 from an unsigned type, to exp,
4584 a signed type, we will be doing the comparison as unsigned.
4585 The tests above have already verified that LOW and HIGH
4586 are both positive.
4588 So we have to ensure that we will handle large unsigned
4589 values the same way that the current signed bounds treat
4590 negative values. */
4593 {
4594 tree high_positive;
4595 tree equiv_type;
4596 /* For fixed-point modes, we need to pass the saturating flag
4597 as the 2nd parameter. */
4602 else
4606 /* A range without an upper bound is, naturally, unbounded.
4607 Since convert would have cropped a very large value, use
4608 the max value for the destination type. */
4609 high_positive
4616 high_positive),
4619 /* If the low bound is specified, "and" the range with the
4620 range for which the original unsigned value will be
4621 positive. */
4623 {
4627 integer_zero_node),
4628 high_positive))
4632 }
4633 else
4634 {
4635 /* Otherwise, "or" the range with the range of the input
4636 that will be interpreted as negative. */
4640 integer_zero_node),
4641 high_positive))
4645 }
4646 }
4654 }
4657 }
4659 /* If EXP is a constant, we can evaluate whether this is true or false. */
4661 {
4668 }
4672 }
4673 \f
4674 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4675 type, TYPE, return an expression to test if EXP is in (or out of, depending
4676 on IN_P) the range. Return 0 if the test couldn't be created. */
4678 static tree
4680 {
4682 tree value;
4684 #ifdef HAVE_canonicalize_funcptr_for_compare
4685 /* Disable this optimization for function pointer expressions
4686 on targets that require function pointer canonicalization. */
4691 #endif
4694 {
4700 }
4718 {
4720 {
4724 }
4726 }
4728 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4730 {
4732 HOST_WIDE_INT hi;
4737 {
4740 }
4741 else
4742 {
4745 }
4748 {
4750 {
4753 etype
4755 else
4758 }
4761 }
4762 }
4764 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4765 This requires wrap-around arithmetics for the type of the expression. */
4767 {
4769 /* There is no requirement that LOW be within the range of ETYPE
4770 if the latter is a subtype. It must, however, be within the base
4771 type of ETYPE. So be sure we do the subtraction in that type. */
4784 }
4794 {
4796 {
4802 }
4804 }
4812 }
4813 \f
4814 /* Return the predecessor of VAL in its type, handling the infinite case. */
4816 static tree
4818 {
4824 else
4826 }
4828 /* Return the successor of VAL in its type, handling the infinite case. */
4830 static tree
4832 {
4838 else
4840 }
4842 /* Given two ranges, see if we can merge them into one. Return 1 if we
4843 can, 0 if we can't. Set the output range into the specified parameters. */
4845 static int
4848 {
4852 tree tem;
4862 /* Make range 0 be the range that starts first, or ends last if they
4863 start at the same value. Swap them if it isn't. */
4866 || (lowequal
4869 {
4873 }
4875 /* Now flag two cases, whether the ranges are disjoint or whether the
4876 second range is totally subsumed in the first. Note that the tests
4877 below are simplified by the ones above. */
4883 /* We now have four cases, depending on whether we are including or
4884 excluding the two ranges. */
4886 {
4887 /* If they don't overlap, the result is false. If the second range
4888 is a subset it is the result. Otherwise, the range is from the start
4889 of the second to the end of the first. */
4894 else
4896 }
4899 {
4900 /* If they don't overlap, the result is the first range. If they are
4901 equal, the result is false. If the second range is a subset of the
4902 first, and the ranges begin at the same place, we go from just after
4903 the end of the second range to the end of the first. If the second
4904 range is not a subset of the first, or if it is a subset and both
4905 ranges end at the same place, the range starts at the start of the
4906 first range and ends just before the second range.
4907 Otherwise, we can't describe this as a single range. */
4913 {
4918 {
4919 /* We are in the weird situation where high0 > high1 but
4920 high1 has no successor. Punt. */
4922 }
4923 }
4925 {
4930 {
4931 /* low0 < low1 but low1 has no predecessor. Punt. */
4933 }
4934 }
4935 else
4937 }
4940 {
4941 /* If they don't overlap, the result is the second range. If the second
4942 is a subset of the first, the result is false. Otherwise,
4943 the range starts just after the first range and ends at the
4944 end of the second. */
4949 else
4950 {
4955 {
4956 /* high1 > high0 but high0 has no successor. Punt. */
4958 }
4959 }
4960 }
4962 else
4963 {
4964 /* The case where we are excluding both ranges. Here the complex case
4965 is if they don't overlap. In that case, the only time we have a
4966 range is if they are adjacent. If the second is a subset of the
4967 first, the result is the first. Otherwise, the range to exclude
4968 starts at the beginning of the first range and ends at the end of the
4969 second. */
4971 {
4976 else
4977 {
4978 /* Canonicalize - [min, x] into - [-, x]. */
4981 {
4986 /* FALLTHROUGH */
4999 }
5001 /* Canonicalize - [x, max] into - [x, -]. */
5004 {
5009 /* FALLTHROUGH */
5024 }
5026 /* The ranges might be also adjacent between the maximum and
5027 minimum values of the given type. For
5028 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5029 return + [x + 1, y - 1]. */
5031 {
5038 }
5039 else
5041 }
5042 }
5045 else
5047 }
5051 }
5052 \f
5054 /* Subroutine of fold, looking inside expressions of the form
5055 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5056 of the COND_EXPR. This function is being used also to optimize
5057 A op B ? C : A, by reversing the comparison first.
5059 Return a folded expression whose code is not a COND_EXPR
5060 anymore, or NULL_TREE if no folding opportunity is found. */
5062 static tree
5064 {
5069 tree tem;
5074 /* If we have A op 0 ? A : -A, consider applying the following
5075 transformations:
5077 A == 0? A : -A same as -A
5078 A != 0? A : -A same as A
5079 A >= 0? A : -A same as abs (A)
5080 A > 0? A : -A same as abs (A)
5081 A <= 0? A : -A same as -abs (A)
5082 A < 0? A : -A same as -abs (A)
5084 None of these transformations work for modes with signed
5085 zeros. If A is +/-0, the first two transformations will
5086 change the sign of the result (from +0 to -0, or vice
5087 versa). The last four will fix the sign of the result,
5088 even though the original expressions could be positive or
5089 negative, depending on the sign of A.
5091 Note that all these transformations are correct if A is
5092 NaN, since the two alternatives (A and -A) are also NaNs. */
5099 /* In the case that A is of the form X-Y, '-A' (arg2) may
5100 have already been folded to Y-X, check for that. */
5108 {
5120 /* Fall through. */
5142 }
5144 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5145 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5146 both transformations are correct when A is NaN: A != 0
5147 is then true, and A == 0 is false. */
5151 {
5156 }
5158 /* Try some transformations of A op B ? A : B.
5160 A == B? A : B same as B
5161 A != B? A : B same as A
5162 A >= B? A : B same as max (A, B)
5163 A > B? A : B same as max (B, A)
5164 A <= B? A : B same as min (A, B)
5165 A < B? A : B same as min (B, A)
5167 As above, these transformations don't work in the presence
5168 of signed zeros. For example, if A and B are zeros of
5169 opposite sign, the first two transformations will change
5170 the sign of the result. In the last four, the original
5171 expressions give different results for (A=+0, B=-0) and
5172 (A=-0, B=+0), but the transformed expressions do not.
5174 The first two transformations are correct if either A or B
5175 is a NaN. In the first transformation, the condition will
5176 be false, and B will indeed be chosen. In the case of the
5177 second transformation, the condition A != B will be true,
5178 and A will be chosen.
5180 The conversions to max() and min() are not correct if B is
5181 a number and A is not. The conditions in the original
5182 expressions will be false, so all four give B. The min()
5183 and max() versions would give a NaN instead. */
5186 /* Avoid these transformations if the COND_EXPR may be used
5187 as an lvalue in the C++ front-end. PR c++/19199. */
5188 && (in_gimple_form
5193 {
5198 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5200 {
5204 }
5207 {
5216 /* In C++ a ?: expression can be an lvalue, so put the
5217 operand which will be used if they are equal first
5218 so that we can convert this back to the
5219 corresponding COND_EXPR. */
5221 {
5228 }
5235 {
5242 }
5255 }
5256 }
5258 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5259 we might still be able to simplify this. For example,
5260 if C1 is one less or one more than C2, this might have started
5261 out as a MIN or MAX and been transformed by this function.
5262 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5268 {
5270 /* We can replace A with C1 in this case. */
5275 /* If C1 is C2 + 1, this is min(A, C2). */
5277 OEP_ONLY_CONST)
5281 OEP_ONLY_CONST))
5283 type,
5285 arg2));
5289 /* If C1 is C2 - 1, this is min(A, C2). */
5291 OEP_ONLY_CONST)
5295 OEP_ONLY_CONST))
5297 type,
5299 arg2));
5303 /* If C1 is C2 - 1, this is max(A, C2). */
5305 OEP_ONLY_CONST)
5309 OEP_ONLY_CONST))
5311 type,
5313 arg2));
5317 /* If C1 is C2 + 1, this is max(A, C2). */
5319 OEP_ONLY_CONST)
5323 OEP_ONLY_CONST))
5325 type,
5327 arg2));
5333 }
5336 }
5339 \f
5340 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5341 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5342 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5343 false) >= 2)
5344 #endif
5346 /* EXP is some logical combination of boolean tests. See if we can
5347 merge it into some range test. Return the new tree if so. */
5349 static tree
5351 {
5359 tree tem;
5363 /* If this is an OR operation, invert both sides; we will invert
5364 again at the end. */
5368 /* If both expressions are the same, if we can merge the ranges, and we
5369 can build the range test, return it or it inverted. If one of the
5370 ranges is always true or always false, consider it to be the same
5371 expression as the other. */
5379 {
5383 }
5385 /* On machines where the branch cost is expensive, if this is a
5386 short-circuited branch and the underlying object on both sides
5387 is the same, make a non-short-circuit operation. */
5393 {
5394 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5395 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5396 which cases we can't do this. */
5404 {
5413 {
5416 WARN_STRICT_OVERFLOW_COMPARISON);
5420 }
5421 }
5422 }
5425 }
5426 \f
5427 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5428 bit value. Arrange things so the extra bits will be set to zero if and
5429 only if C is signed-extended to its full width. If MASK is nonzero,
5430 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5432 static tree
5434 {
5437 tree temp;
5442 /* We work by getting just the sign bit into the low-order bit, then
5443 into the high-order bit, then sign-extend. We then XOR that value
5444 with C. */
5448 /* We must use a signed type in order to get an arithmetic right shift.
5449 However, we must also avoid introducing accidental overflows, so that
5450 a subsequent call to integer_zerop will work. Hence we must
5451 do the type conversion here. At this point, the constant is either
5452 zero or one, and the conversion to a signed type can never overflow.
5453 We could get an overflow if this conversion is done anywhere else. */
5462 /* If necessary, convert the type back to match the type of C. */
5467 }
5468 \f
5469 /* Find ways of folding logical expressions of LHS and RHS:
5470 Try to merge two comparisons to the same innermost item.
5471 Look for range tests like "ch >= '0' && ch <= '9'".
5472 Look for combinations of simple terms on machines with expensive branches
5473 and evaluate the RHS unconditionally.
5475 For example, if we have p->a == 2 && p->b == 4 and we can make an
5476 object large enough to span both A and B, we can do this with a comparison
5477 against the object ANDed with the a mask.
5479 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5480 operations to do this with one comparison.
5482 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5483 function and the one above.
5485 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5486 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5488 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5489 two operands.
5491 We return the simplified tree or 0 if no optimization is possible. */
5493 static tree
5495 {
5496 /* If this is the "or" of two comparisons, we can do something if
5497 the comparisons are NE_EXPR. If this is the "and", we can do something
5498 if the comparisons are EQ_EXPR. I.e.,
5499 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5501 WANTED_CODE is this operation code. For single bit fields, we can
5502 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5503 comparison for one-bit fields. */
5525 /* Start by getting the comparison codes. Fail if anything is volatile.
5526 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5527 it were surrounded with a NE_EXPR. */
5536 {
5540 }
5543 {
5547 }
5558 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5561 {
5562 tree result;
5565 {
5570 }
5573 {
5579 }
5580 }
5585 /* If the RHS can be evaluated unconditionally and its operands are
5586 simple, it wins to evaluate the RHS unconditionally on machines
5587 with expensive branches. In this case, this isn't a comparison
5588 that can be merged. Avoid doing this if the RHS is a floating-point
5589 comparison since those can trap. */
5596 {
5597 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5608 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5620 {
5624 }
5625 }
5627 /* See if the comparisons can be merged. Then get all the parameters for
5628 each side. */
5652 /* It must be true that the inner operation on the lhs of each
5653 comparison must be the same if we are to be able to do anything.
5654 Then see if we have constants. If not, the same must be true for
5655 the rhs's. */
5666 else
5669 /* If either comparison code is not correct for our logical operation,
5670 fail. However, we can convert a one-bit comparison against zero into
5671 the opposite comparison against that bit being set in the field. */
5675 {
5677 {
5678 /* Make the left operand unsigned, since we are only interested
5679 in the value of one bit. Otherwise we are doing the wrong
5680 thing below. */
5683 }
5684 else
5686 }
5688 /* This is analogous to the code for l_const above. */
5690 {
5692 {
5695 }
5696 else
5698 }
5700 /* See if we can find a mode that contains both fields being compared on
5701 the left. If we can't, fail. Otherwise, update all constants and masks
5702 to be relative to a field of that size. */
5707 volatilep);
5717 {
5720 }
5728 {
5736 {
5740 }
5741 }
5743 {
5751 {
5755 }
5756 }
5758 /* If the right sides are not constant, do the same for it. Also,
5759 disallow this optimization if a size or signedness mismatch occurs
5760 between the left and right sides. */
5762 {
5765 /* Make sure the two fields on the right
5766 correspond to the left without being swapped. */
5774 volatilep);
5784 {
5787 }
5794 /* Make a mask that corresponds to both fields being compared.
5795 Do this for both items being compared. If the operands are the
5796 same size and the bits being compared are in the same position
5797 then we can do this by masking both and comparing the masked
5798 results. */
5802 {
5814 }
5816 /* There is still another way we can do something: If both pairs of
5817 fields being compared are adjacent, we may be able to make a wider
5818 field containing them both.
5820 Note that we still must mask the lhs/rhs expressions. Furthermore,
5821 the mask must be shifted to account for the shift done by
5822 make_bit_field_ref. */
5827 {
5828 tree type;
5840 /* Convert to the smaller type before masking out unwanted bits. */
5843 {
5845 {
5849 }
5851 {
5855 }
5856 }
5865 }
5868 }
5870 /* Handle the case of comparisons with constants. If there is something in
5871 common between the masks, those bits of the constants must be the same.
5872 If not, the condition is always false. Test for this to avoid generating
5873 incorrect code below. */
5878 {
5880 {
5883 }
5884 else
5885 {
5888 }
5889 }
5891 /* Construct the expression we will return. First get the component
5892 reference we will make. Unless the mask is all ones the width of
5893 that field, perform the mask operation. Then compare with the
5894 merged constant. */
5904 }
5905 \f
5906 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5907 constant. */
5909 static tree
5911 {
5914 tree comp_const;
5915 tree minmax_const;
5917 tree inner;
5928 /* If something does not permit us to optimize, return the original tree. */
5936 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5937 and GT_EXPR, doing the rest with recursive calls using logical
5938 simplifications. */
5940 {
5942 {
5948 }
5951 return
5953 optimize_minmax_comparison
5955 optimize_minmax_comparison
5960 /* MAX (X, 0) == 0 -> X <= 0 */
5964 /* MAX (X, 0) == 5 -> X == 5 */
5968 /* MAX (X, 0) == -1 -> false */
5972 /* MIN (X, 0) == 0 -> X >= 0 */
5976 /* MIN (X, 0) == 5 -> false */
5979 else
5980 /* MIN (X, 0) == -1 -> X == -1 */
5985 /* MAX (X, 0) > 0 -> X > 0
5986 MAX (X, 0) > 5 -> X > 5 */
5990 /* MAX (X, 0) > -1 -> true */
5994 /* MIN (X, 0) > 0 -> false
5995 MIN (X, 0) > 5 -> false */
5998 else
5999 /* MIN (X, 0) > -1 -> X > -1 */
6004 }
6005 }
6006 \f
6007 /* T is an integer expression that is being multiplied, divided, or taken a
6008 modulus (CODE says which and what kind of divide or modulus) by a
6009 constant C. See if we can eliminate that operation by folding it with
6010 other operations already in T. WIDE_TYPE, if non-null, is a type that
6011 should be used for the computation if wider than our type.
6013 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6014 (X * 2) + (Y * 4). We must, however, be assured that either the original
6015 expression would not overflow or that overflow is undefined for the type
6016 in the language in question.
6018 If we return a non-null expression, it is an equivalent form of the
6019 original computation, but need not be in the original type.
6021 We set *STRICT_OVERFLOW_P to true if the return values depends on
6022 signed overflow being undefined. Otherwise we do not change
6023 *STRICT_OVERFLOW_P. */
6025 static tree
6028 {
6029 /* To avoid exponential search depth, refuse to allow recursion past
6030 three levels. Beyond that (1) it's highly unlikely that we'll find
6031 something interesting and (2) we've probably processed it before
6032 when we built the inner expression. */
6035 tree ret;
6040 depth++;
6042 depth--;
6045 }
6047 static tree
6050 {
6061 /* Don't deal with constants of zero here; they confuse the code below. */
6071 /* Note that we need not handle conditional operations here since fold
6072 already handles those cases. So just do arithmetic here. */
6074 {
6076 /* For a constant, we can always simplify if we are a multiply
6077 or (for divide and modulus) if it is a multiple of our constant. */
6085 /* If op0 is an expression ... */
6091 /* ... and has wrapping overflow, and its type is smaller
6092 than ctype, then we cannot pass through as widening. */
6098 /* ... or this is a truncation (t is narrower than op0),
6099 then we cannot pass through this narrowing. */
6102 /* ... or signedness changes for division or modulus,
6103 then we cannot pass through this conversion. */
6107 /* ... or has undefined overflow while the converted to
6108 type has not, we cannot do the operation in the inner type
6109 as that would introduce undefined overflow. */
6114 /* Pass the constant down and see if we can make a simplification. If
6115 we can, replace this expression with the inner simplification for
6116 possible later conversion to our or some other type. */
6121 code == MULT_EXPR
6123 strict_overflow_p))))
6128 /* If widening the type changes it from signed to unsigned, then we
6129 must avoid building ABS_EXPR itself as unsigned. */
6131 {
6135 {
6138 }
6140 }
6141 /* If the constant is negative, we cannot simplify this. */
6144 /* FALLTHROUGH */
6152 /* If widening the type changes the signedness, then we can't perform
6153 this optimization as that changes the result. */
6157 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6163 {
6170 }
6174 /* If the second operand is constant, this is a multiplication
6175 or floor division, by a power of two, so we can treat it that
6176 way unless the multiplier or divisor overflows. Signed
6177 left-shift overflow is implementation-defined rather than
6178 undefined in C90, so do not convert signed left shift into
6179 multiplication. */
6182 /* const_binop may not detect overflow correctly,
6183 so check for it explicitly here. */
6188 size_one_node,
6198 /* See if we can eliminate the operation on both sides. If we can, we
6199 can return a new PLUS or MINUS. If we can't, the only remaining
6200 cases where we can do anything are if the second operand is a
6201 constant. */
6207 /* If not multiplication, we can only do this if both operands
6208 are divisible by c. */
6211 {
6216 }
6218 /* If this was a subtraction, negate OP1 and set it to be an addition.
6219 This simplifies the logic below. */
6226 /* If either OP1 or C are negative, this optimization is not safe for
6227 some of the division and remainder types while for others we need
6228 to change the code. */
6230 {
6238 }
6240 /* If it's a multiply or a division/modulus operation of a multiple
6241 of our constant, do the operation. */
6244 {
6249 }
6250 else
6253 /* If we have an unsigned type is not a sizetype, we cannot widen
6254 the operation since it will change the result if the original
6255 computation overflowed. */
6261 /* If we were able to eliminate our operation from the first side,
6262 apply our operation to the second side and reform the PLUS. */
6266 /* The last case is if we are a multiply. In that case, we can
6267 apply the distributive law to commute the multiply and addition
6268 if the multiplication of the constants doesn't overflow. */
6274 op1);
6279 /* We have a special case here if we are doing something like
6280 (C * 8) % 4 since we know that's zero. */
6283 /* If the multiplication can overflow we cannot optimize this.
6284 ??? Until we can properly mark individual operations as
6285 not overflowing we need to treat sizetype special here as
6286 stor-layout relies on this opimization to make
6287 DECL_FIELD_BIT_OFFSET always a constant. */
6293 {
6296 }
6298 /* ... fall through ... */
6302 /* If we can extract our operation from the LHS, do so and return a
6303 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6304 do something only if the second operand is a constant. */
6318 /* If these are the same operation types, we can associate them
6319 assuming no overflow. */
6331 /* If these operations "cancel" each other, we have the main
6332 optimizations of this pass, which occur when either constant is a
6333 multiple of the other, in which case we replace this with either an
6334 operation or CODE or TCODE.
6336 If we have an unsigned type that is not a sizetype, we cannot do
6337 this since it will change the result if the original computation
6338 overflowed. */
6346 {
6348 {
6355 }
6357 {
6364 }
6365 }
6370 }
6373 }
6374 \f
6375 /* Return a node which has the indicated constant VALUE (either 0 or
6376 1), and is of the indicated TYPE. */
6378 tree
6380 {
6385 else
6387 }
6390 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6391 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6392 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6393 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6394 COND is the first argument to CODE; otherwise (as in the example
6395 given here), it is the second argument. TYPE is the type of the
6396 original expression. Return NULL_TREE if no simplification is
6397 possible. */
6399 static tree
6403 {
6410 /* This transformation is only worthwhile if we don't have to wrap
6411 arg in a SAVE_EXPR, and the operation can be simplified on at least
6412 one of the branches once its pushed inside the COND_EXPR. */
6417 {
6421 /* If this operand throws an expression, then it does not make
6422 sense to try to perform a logical or arithmetic operation
6423 involving it. */
6428 }
6429 else
6430 {
6435 }
6439 {
6443 else
6445 }
6447 {
6451 else
6453 }
6457 }
6459 \f
6460 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6462 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6463 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6464 ADDEND is the same as X.
6466 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6467 and finite. The problematic cases are when X is zero, and its mode
6468 has signed zeros. In the case of rounding towards -infinity,
6469 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6470 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6472 bool
6474 {
6478 /* Don't allow the fold with -fsignaling-nans. */
6482 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6486 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6491 /* The mode has signed zeros, and we have to honor their sign.
6492 In this situation, there is only one case we can return true for.
6493 X - 0 is the same as X unless rounding towards -infinity is
6494 supported. */
6496 }
6498 /* Subroutine of fold() that checks comparisons of built-in math
6499 functions against real constants.
6501 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6502 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6503 is the type of the result and ARG0 and ARG1 are the operands of the
6504 comparison. ARG1 must be a TREE_REAL_CST.
6506 The function returns the constant folded tree if a simplification
6507 can be made, and NULL_TREE otherwise. */
6509 static tree
6512 {
6513 REAL_VALUE_TYPE c;
6516 {
6522 {
6523 /* sqrt(x) < y is always false, if y is negative. */
6527 /* sqrt(x) > y is always true, if y is negative and we
6528 don't care about NaNs, i.e. negative values of x. */
6532 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6535 }
6537 {
6538 REAL_VALUE_TYPE c2;
6544 {
6545 /* sqrt(x) > y is x == +Inf, when y is very large. */
6550 /* sqrt(x) > y is always false, when y is very large
6551 and we don't care about infinities. */
6553 }
6555 /* sqrt(x) > c is the same as x > c*c. */
6558 }
6560 {
6561 REAL_VALUE_TYPE c2;
6567 {
6568 /* sqrt(x) < y is always true, when y is a very large
6569 value and we don't care about NaNs or Infinities. */
6573 /* sqrt(x) < y is x != +Inf when y is very large and we
6574 don't care about NaNs. */
6579 /* sqrt(x) < y is x >= 0 when y is very large and we
6580 don't care about Infinities. */
6585 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6594 dconst0)),
6597 c2)));
6598 }
6600 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6605 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6608 {
6613 dconst0)),
6616 c2)));
6617 }
6618 }
6619 }
6622 }
6624 /* Subroutine of fold() that optimizes comparisons against Infinities,
6625 either +Inf or -Inf.
6627 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6628 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6629 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6631 The function returns the constant folded tree if a simplification
6632 can be made, and NULL_TREE otherwise. */
6634 static tree
6636 {
6638 REAL_VALUE_TYPE max;
6639 tree temp;
6644 /* For negative infinity swap the sense of the comparison. */
6650 {
6652 /* x > +Inf is always false, if with ignore sNANs. */
6658 /* x <= +Inf is always true, if we don't case about NaNs. */
6662 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6665 {
6668 }
6673 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6679 /* x < +Inf is always equal to x <= DBL_MAX. */
6685 /* x != +Inf is always equal to !(x > DBL_MAX). */
6697 }
6700 }
6702 /* Subroutine of fold() that optimizes comparisons of a division by
6703 a nonzero integer constant against an integer constant, i.e.
6704 X/C1 op C2.
6706 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6707 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6708 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6710 The function returns the constant folded tree if a simplification
6711 can be made, and NULL_TREE otherwise. */
6713 static tree
6715 {
6720 HOST_WIDE_INT hpart;
6725 /* We have to do this the hard way to detect unsigned overflow.
6726 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6737 {
6742 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6750 }
6752 {
6756 {
6775 }
6776 }
6777 else
6778 {
6779 /* A negative divisor reverses the relational operators. */
6785 {
6804 }
6805 }
6808 {
6829 {
6832 }
6837 {
6840 }
6845 {
6848 }
6853 {
6856 }
6861 }
6864 }
6867 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6868 equality/inequality test, then return a simplified form of the test
6869 using a sign testing. Otherwise return NULL. TYPE is the desired
6870 result type. */
6872 static tree
6874 tree result_type)
6875 {
6876 /* If this is testing a single bit, we can optimize the test. */
6880 {
6881 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6882 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6886 /* This is only a win if casting to a signed type is cheap,
6887 i.e. when arg00's type is not a partial mode. */
6890 {
6895 }
6896 }
6899 }
6901 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6902 equality/inequality test, then return a simplified form of
6903 the test using shifts and logical operations. Otherwise return
6904 NULL. TYPE is the desired result type. */
6906 tree
6908 tree result_type)
6909 {
6910 /* If this is testing a single bit, we can optimize the test. */
6914 {
6923 /* First, see if we can fold the single bit test into a sign-bit
6924 test. */
6926 result_type);
6930 /* Otherwise we have (A & C) != 0 where C is a single bit,
6931 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6932 Similarly for (A & C) == 0. */
6934 /* If INNER is a right shift of a constant and it plus BITNUM does
6935 not overflow, adjust BITNUM and INNER. */
6942 {
6945 }
6947 /* If we are going to be able to omit the AND below, we must do our
6948 operations as unsigned. If we must use the AND, we have a choice.
6949 Normally unsigned is faster, but for some machines signed is. */
6950 #ifdef LOAD_EXTEND_OP
6953 #else
6955 #endif
6971 /* Put the AND last so it can combine with more things. */
6974 /* Make sure to return the proper type. */
6978 }
6980 }
6982 /* Check whether we are allowed to reorder operands arg0 and arg1,
6983 such that the evaluation of arg1 occurs before arg0. */
6985 static bool
6987 {
6994 }
6996 /* Test whether it is preferable two swap two operands, ARG0 and
6997 ARG1, for example because ARG0 is an integer constant and ARG1
6998 isn't. If REORDER is true, only recommend swapping if we can
6999 evaluate the operands in reverse order. */
7001 bool
7003 {
7039 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7040 for commutative and comparison operators. Ensuring a canonical
7041 form allows the optimizers to find additional redundancies without
7042 having to explicitly check for both orderings. */
7048 /* Put SSA_NAMEs last. */
7054 /* Put variables last. */
7061 }
7063 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7064 ARG0 is extended to a wider type. */
7066 static tree
7068 {
7070 tree arg1_unw;
7079 #ifdef HAVE_canonicalize_funcptr_for_compare
7080 /* Disable this optimization if we're casting a function pointer
7081 type on targets that require function pointer canonicalization. */
7086 #endif
7093 /* If possible, express the comparison in the shorter mode. */
7113 /* If we are comparing with the integer that does not fit into the range
7114 of the shorter type, the result is known. */
7125 {
7152 }
7155 }
7157 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7158 ARG0 just the signedness is changed. */
7160 static tree
7163 {
7164 tree arg0_inner;
7174 #ifdef HAVE_canonicalize_funcptr_for_compare
7175 /* Disable this optimization if we're casting a function pointer
7176 type on targets that require function pointer canonicalization. */
7181 #endif
7186 /* If the conversion is from an integral subtype to its basetype
7187 leave it alone. */
7206 else
7210 }
7212 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7213 step of the array. Reconstructs s and delta in the case of s * delta
7214 being an integer constant (and thus already folded).
7215 ADDR is the address. MULT is the multiplicative expression.
7216 If the function succeeds, the new address expression is returned. Otherwise
7217 NULL_TREE is returned. */
7219 static tree
7221 {
7225 tree itype;
7228 /* Strip the nops that might be added when converting op1 to sizetype. */
7231 /* Canonicalize op1 into a possibly non-constant delta
7232 and an INTEGER_CST s. */
7234 {
7241 {
7244 }
7246 {
7249 }
7250 else
7252 }
7254 {
7257 }
7258 else
7259 {
7260 /* Simulate we are delta * 1. */
7263 }
7266 {
7268 {
7269 /* Remember if this was a multi-dimensional array. */
7282 {
7285 }
7286 else
7287 {
7288 /* Try if delta is a multiple of step. */
7293 }
7295 /* Only fold here if we can verify we do not overflow one
7296 dimension of a multi-dimensional array. */
7298 {
7299 tree tmp;
7315 }
7318 }
7319 else
7324 }
7326 /* We found the suitable array reference. So copy everything up to it,
7327 and replace the index. */
7334 {
7338 }
7346 }
7349 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7350 means A >= Y && A != MAX, but in this case we know that
7351 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7353 static tree
7355 {
7362 else
7371 {
7374 }
7376 {
7379 }
7380 else
7387 {
7388 /* Convert the pointer types into integer before taking the difference. */
7392 }
7393 else
7400 }
7402 /* Fold a sum or difference of at least one multiplication.
7403 Returns the folded tree or NULL if no simplification could be made. */
7405 static tree
7407 {
7411 /* (A * C) +- (B * C) -> (A+-B) * C.
7412 (A * C) +- A -> A * (C+-1).
7413 We are most concerned about the case where C is a constant,
7414 but other combinations show up during loop reduction. Since
7415 it is not difficult, try all four possibilities. */
7418 {
7421 }
7423 {
7426 }
7427 else
7428 {
7429 /* We cannot generate constant 1 for fract. */
7434 }
7436 {
7439 }
7441 {
7443 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7444 the purpose of this canonicalization. */
7448 {
7451 }
7452 else
7454 }
7455 else
7456 {
7457 /* We cannot generate constant 1 for fract. */
7462 }
7474 /* No identical multiplicands; see if we can find a common
7475 power-of-two factor in non-power-of-two multiplies. This
7476 can help in multi-dimensional array access. */
7479 {
7482 tree maybe_same;
7486 /* Move min of absolute values to int11. */
7489 {
7494 }
7495 else
7499 {
7507 }
7508 }
7518 }
7520 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7521 specified by EXPR into the buffer PTR of length LEN bytes.
7522 Return the number of bytes placed in the buffer, or zero
7523 upon failure. */
7525 static int
7527 {
7538 {
7542 else
7547 {
7554 else
7556 }
7557 else
7560 }
7562 }
7565 /* Subroutine of native_encode_expr. Encode the REAL_CST
7566 specified by EXPR into the buffer PTR of length LEN bytes.
7567 Return the number of bytes placed in the buffer, or zero
7568 upon failure. */
7570 static int
7572 {
7578 /* There are always 32 bits in each long, no matter the size of
7579 the hosts long. We handle floating point representations with
7580 up to 192 bits. */
7591 {
7596 {
7603 else
7605 }
7606 else
7609 }
7611 }
7613 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7614 specified by EXPR into the buffer PTR of length LEN bytes.
7615 Return the number of bytes placed in the buffer, or zero
7616 upon failure. */
7618 static int
7620 {
7622 tree part;
7633 }
7636 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7637 specified by EXPR into the buffer PTR of length LEN bytes.
7638 Return the number of bytes placed in the buffer, or zero
7639 upon failure. */
7641 static int
7643 {
7653 {
7655 {
7658 }
7659 else
7663 {
7666 }
7667 else
7668 {
7672 }
7674 }
7676 }
7679 /* Subroutine of native_encode_expr. Encode the STRING_CST
7680 specified by EXPR into the buffer PTR of length LEN bytes.
7681 Return the number of bytes placed in the buffer, or zero
7682 upon failure. */
7684 static int
7686 {
7688 HOST_WIDE_INT total_bytes;
7699 {
7703 }
7704 else
7707 }
7710 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7711 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7712 buffer PTR of length LEN bytes. Return the number of bytes
7713 placed in the buffer, or zero upon failure. */
7715 int
7717 {
7719 {
7737 }
7738 }
7741 /* Subroutine of native_interpret_expr. Interpret the contents of
7742 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7743 If the buffer cannot be interpreted, return NULL_TREE. */
7745 static tree
7747 {
7761 {
7764 {
7771 else
7773 }
7774 else
7780 else
7783 }
7786 }
7789 /* Subroutine of native_interpret_expr. Interpret the contents of
7790 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7791 If the buffer cannot be interpreted, return NULL_TREE. */
7793 static tree
7795 {
7800 /* There are always 32 bits in each long, no matter the size of
7801 the hosts long. We handle floating point representations with
7802 up to 192 bits. */
7803 REAL_VALUE_TYPE r;
7814 {
7817 {
7824 else
7826 }
7827 else
7832 }
7836 }
7839 /* Subroutine of native_interpret_expr. Interpret the contents of
7840 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7841 If the buffer cannot be interpreted, return NULL_TREE. */
7843 static tree
7845 {
7860 }
7863 /* Subroutine of native_interpret_expr. Interpret the contents of
7864 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7865 If the buffer cannot be interpreted, return NULL_TREE. */
7867 static tree
7869 {
7881 {
7886 }
7888 }
7891 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7892 the buffer PTR of length LEN as a constant of type TYPE. For
7893 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7894 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7895 return NULL_TREE. */
7897 tree
7899 {
7901 {
7918 }
7919 }
7922 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7923 TYPE at compile-time. If we're unable to perform the conversion
7924 return NULL_TREE. */
7926 static tree
7928 {
7929 /* We support up to 512-bit values (for V8DFmode). */
7933 /* Check that the host and target are sane. */
7942 }
7944 /* Build an expression for the address of T. Folds away INDIRECT_REF
7945 to avoid confusing the gimplify process. When IN_FOLD is true
7946 avoid modifications of T. */
7948 static tree
7950 {
7951 /* The size of the object is not relevant when talking about its address. */
7955 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7958 {
7963 }
7965 {
7975 }
7976 else
7980 }
7982 /* Build an expression for the address of T with type PTRTYPE. This
7983 function modifies the input parameter 'T' by sometimes setting the
7984 TREE_ADDRESSABLE flag. */
7986 tree
7988 {
7990 }
7992 /* Build an expression for the address of T. This function modifies
7993 the input parameter 'T' by sometimes setting the TREE_ADDRESSABLE
7994 flag. When called from fold functions, use fold_addr_expr instead. */
7996 tree
7998 {
8002 }
8004 /* Same as build_fold_addr_expr, builds an expression for the address
8005 of T, but avoids touching the input node 't'. Fold functions
8006 should use this version. */
8008 static tree
8010 {
8014 }
8016 /* Fold a unary expression of code CODE and type TYPE with operand
8017 OP0. Return the folded expression if folding is successful.
8018 Otherwise, return NULL_TREE. */
8020 tree
8022 {
8023 tree tem;
8024 tree arg0;
8032 {
8035 {
8036 /* Don't use STRIP_NOPS, because signedness of argument type
8037 matters. */
8039 }
8040 else
8041 {
8042 /* Strip any conversions that don't change the mode. This
8043 is safe for every expression, except for a comparison
8044 expression because its signedness is derived from its
8045 operands.
8047 Note that this is done as an internal manipulation within
8048 the constant folder, in order to find the simplest
8049 representation of the arguments so that their form can be
8050 studied. In any cases, the appropriate type conversions
8051 should be put back in the tree that will get out of the
8052 constant folder. */
8054 }
8055 }
8058 {
8065 {
8077 /* If this was a conversion, and all we did was to move into
8078 inside the COND_EXPR, bring it back out. But leave it if
8079 it is a conversion from integer to integer and the
8080 result precision is no wider than a word since such a
8081 conversion is cheap and may be optimized away by combine,
8082 while it couldn't if it were outside the COND_EXPR. Then return
8083 so we don't get into an infinite recursion loop taking the
8084 conversion out and then back in. */
8096 && (INTEGRAL_TYPE_P
8108 }
8110 {
8112 {
8116 }
8120 integer_one_node),
8122 integer_zero_node));
8123 }
8124 }
8127 {
8129 /* Re-association barriers around constants and other re-association
8130 barriers can be removed. */
8136 CASE_CONVERT:
8142 /* If we have (type) (a CMP b) and type is an integral type, return
8143 new expression involving the new type. */
8148 /* Handle cases of two conversions in a row. */
8150 {
8172 /* In addition to the cases of two conversions in a row
8173 handled below, if we are converting something to its own
8174 type via an object of identical or wider precision, neither
8175 conversion is needed. */
8182 /* Likewise, if the intermediate and final types are either both
8183 float or both integer, we don't need the middle conversion if
8184 it is wider than the final type and doesn't change the signedness
8185 (for integers). Avoid this if the final type is a pointer
8186 since then we sometimes need the inner conversion. Likewise if
8187 the outer has a precision not equal to the size of its mode. */
8196 && ! final_ptr
8200 /* If we have a sign-extension of a zero-extended value, we can
8201 replace that by a single zero-extension. */
8207 /* Two conversions in a row are not needed unless:
8208 - some conversion is floating-point (overstrict for now), or
8209 - some conversion is a vector (overstrict for now), or
8210 - the intermediate type is narrower than both initial and
8211 final, or
8212 - the intermediate type and innermost type differ in signedness,
8213 and the outermost type is wider than the intermediate, or
8214 - the initial type is a pointer type and the precisions of the
8215 intermediate and final types differ, or
8216 - the final type is a pointer type and the precisions of the
8217 initial and intermediate types differ. */
8231 }
8233 /* Handle (T *)&A.B.C for A being of type T and B and C
8234 living at offset zero. This occurs frequently in
8235 C++ upcasting and then accessing the base. */
8239 {
8241 tree offset;
8247 /* If the reference was to a (constant) zero offset, we can use
8248 the address of the base if it has the same base type
8249 as the result type. */
8254 }
8258 /* Detect assigning a bitfield. */
8260 && DECL_BIT_FIELD
8262 {
8263 /* Don't leave an assignment inside a conversion
8264 unless assigning a bitfield. */
8266 /* First do the assignment, then return converted constant. */
8271 }
8273 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8274 constants (if x has signed type, the sign bit cannot be set
8275 in c). This folds extension into the BIT_AND_EXPR.
8276 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8277 very likely don't have maximal range for their precision and this
8278 transformation effectively doesn't preserve non-maximal ranges. */
8282 /* Not if the conversion is to the sub-type. */
8284 {
8294 <= HOST_BITS_PER_WIDE_INT
8296 {
8303 #ifdef LOAD_EXTEND_OP
8305 && !flag_syntax_only
8308 {
8312 }
8313 #endif
8314 }
8316 {
8322 }
8323 }
8325 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type. */
8328 {
8334 }
8336 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8337 of the same precision, and X is an integer type not narrower than
8338 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8344 {
8349 }
8351 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8352 type of X and Y (integer types only). */
8357 {
8358 /* Be careful to fall back to MULT_EXPR from MULTNV_EXPR. */
8364 }
8379 /* For integral conversions with the same precision or pointer
8380 conversions use a NOP_EXPR instead. */
8386 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8387 a sub-type to its base type as generated by the Ada FE. */
8392 /* Strip inner integral conversions that do not change the precision. */
8416 /* Convert fabs((double)float) into (double)fabsf(float). */
8419 {
8424 targ0));
8425 }
8426 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8432 /* Strip sign ops from argument. */
8434 {
8438 }
8445 {
8450 }
8452 {
8457 }
8467 /* Convert ~ (-A) to A - 1. */
8472 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8480 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8493 /* Perform BIT_NOT_EXPR on each element individually. */
8495 {
8500 {
8502 {
8508 }
8509 else
8512 }
8515 }
8520 /* The argument to invert_truthvalue must have Boolean type. */
8524 /* Note that the operand of this must be an int
8525 and its values must be 0 or 1.
8526 ("true" is a fixed value perhaps depending on the language,
8527 but we don't handle values other than 1 correctly yet.) */
8542 {
8550 }
8552 {
8556 }
8558 {
8562 {
8571 }
8572 }
8584 {
8592 }
8594 {
8598 }
8600 {
8604 {
8613 }
8614 }
8620 }
8623 /* If the operation was a conversion do _not_ mark a resulting constant
8624 with TREE_OVERFLOW if the original constant was not. These conversions
8625 have implementation defined behavior and retaining the TREE_OVERFLOW
8626 flag here would confuse later passes such as VRP. */
8627 tree
8629 {
8638 }
8640 /* Fold a binary expression of code CODE and type TYPE with operands
8641 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8642 Return the folded expression if folding is successful. Otherwise,
8643 return NULL_TREE. */
8645 static tree
8647 {
8654 else
8657 /* MIN (MAX (a, b), b) == b. */
8662 /* MIN (MAX (b, a), b) == b. */
8668 /* MIN (a, MAX (a, b)) == a. */
8674 /* MIN (a, MAX (b, a)) == a. */
8681 }
8683 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8684 by changing CODE to reduce the magnitude of constants involved in
8685 ARG0 of the comparison.
8686 Returns a canonicalized comparison tree if a simplification was
8687 possible, otherwise returns NULL_TREE.
8688 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8689 valid if signed overflow is undefined. */
8691 static tree
8695 {
8701 /* Match A +- CST code arg1 and CST code arg1. We can change the
8702 first form only if the operation does not wrap. */
8704 but that causes problems elsewhere. */
8711 /* Identify the constant in arg0 and its sign. */
8714 else
8718 /* Overflowed constants and zero will cause problems. */
8723 /* See if we can reduce the magnitude of the constant in
8724 arg0 by changing the comparison code. */
8726 {
8727 /* CST <= arg1 -> CST-1 < arg1. */
8730 /* -CST < arg1 -> -CST-1 <= arg1. */
8733 /* CST > arg1 -> CST-1 >= arg1. */
8736 /* -CST >= arg1 -> -CST-1 > arg1. */
8739 else
8741 /* arg1 code' CST' might be more canonical. */
8743 }
8744 else
8745 {
8746 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8750 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8754 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8758 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8762 else
8766 }
8768 /* Now build the constant reduced in magnitude. But not if that
8769 would produce one outside of its types range. */
8777 /* We cannot swap the comparison here as that would cause us to
8778 endlessly recurse. */
8783 /* If A - CST didn't overflow so does A - (CST - 1). So it is safe
8784 to keep the *NV_EXPR variants. */
8788 /* If swapping might yield to a more canonical form, do so. */
8791 else
8793 }
8795 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8796 overflow further. Try to decrease the magnitude of constants involved
8797 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8798 and put sole constants at the second argument position.
8799 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8801 static tree
8804 {
8805 tree t;
8810 /* Try canonicalization by simplifying arg0. */
8815 {
8819 }
8821 /* Try canonicalization by simplifying arg1 using the swapped
8822 comparison. */
8830 }
8832 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8833 space. This is used to avoid issuing overflow warnings for
8834 expressions like &p->x which can not wrap. */
8836 static bool
8838 {
8849 {
8852 }
8855 else
8856 {
8859 }
8874 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8875 array. */
8877 {
8878 HOST_WIDE_INT base_size;
8883 }
8886 }
8888 /* Subroutine of fold_binary. This routine performs all of the
8889 transformations that are common to the equality/inequality
8890 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8891 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8892 fold_binary should call fold_binary. Fold a comparison with
8893 tree code CODE and type TYPE with operands OP0 and OP1. Return
8894 the folded comparison or NULL_TREE. */
8896 static tree
8898 {
8911 /* If one arg is a real or integer constant, put it last. */
8915 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1
8916 if the original addition does not overflow. */
8920 {
8924 tree lhs;
8927 HOST_WIDE_INT hi;
8936 /* If there was overflow on combining the two constants we have to
8937 flip the comparison code. */
8944 "when changing X +- C1 cmp C2 to "
8946 WARN_STRICT_OVERFLOW_COMPARISON);
8948 }
8950 /* For comparisons of pointers we can decompose it to a compile time
8951 comparison of the base objects and the offsets into the object.
8952 This requires at least one operand being an ADDR_EXPR or a
8953 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8959 {
8967 /* Get base and offset for the access. Strip ADDR_EXPR for
8968 get_inner_reference, but put it back by stripping INDIRECT_REF
8969 off the base object if possible. indirect_baseN will be true
8970 if baseN is not an address but refers to the object itself. */
8973 {
8979 else
8981 }
8983 {
8988 }
8992 {
8998 else
9000 }
9002 {
9007 }
9009 /* If we have equivalent bases we might be able to simplify. */
9012 {
9013 /* We can fold this expression to a constant if the non-constant
9014 offset parts are equal. */
9021 {
9028 "occur when comparing P +- C1 with "
9030 WARN_STRICT_OVERFLOW_CONDITIONAL);
9033 {
9047 }
9048 }
9049 /* We can simplify the comparison to a comparison of the variable
9050 offset parts if the constant offset parts are equal.
9051 Be careful to use signed size type here because otherwise we
9052 mess with array offsets in the wrong way. This is possible
9053 because pointer arithmetic is restricted to retain within an
9054 object and overflow on pointer differences is undefined as of
9055 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9059 {
9060 tree signed_size_type_node;
9063 /* By converting to signed size type we cover middle-end pointer
9064 arithmetic which operates on unsigned pointer types of size
9065 type size and ARRAY_REF offsets which are properly sign or
9066 zero extended from their type in case it is narrower than
9067 size type. */
9070 else
9074 else
9082 "occur when comparing P +- C1 with "
9084 WARN_STRICT_OVERFLOW_COMPARISON);
9087 }
9088 }
9089 /* For non-equal bases we can simplify if they are addresses
9090 of local binding decls or constants. */
9092 /* We know that !operand_equal_p (base0, base1, 0)
9093 because the if condition was false. But make
9094 sure two decls are not the same. */
9108 {
9113 }
9114 /* For equal offsets we can simplify to a comparison of the
9115 base addresses. */
9117 && (indirect_base0
9119 && (indirect_base1
9124 {
9130 }
9131 }
9133 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9134 X CMP Y +- C2 +- C1 if X +- C1 does not overflow.. This is then
9135 valid if the resulting offset is smaller in absolute value than the
9136 original one. */
9143 {
9148 tree cst;
9150 HOST_WIDE_INT hi;
9153 "occur when combining constants around "
9156 /* Put the constant on the side where it doesn't overflow and is
9157 of lower absolute value than before if the operation on
9158 the other side doesn't overflow. */
9160 {
9169 {
9173 variable1,
9177 }
9178 }
9181 {
9190 {
9197 variable2);
9198 }
9199 }
9200 }
9202 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9203 signed arithmetic case. That form is created by the compiler
9204 often enough for folding it to be of value. One example is in
9205 computing loop trip counts after Operator Strength Reduction. */
9211 {
9220 "eliminating multiplication in comparison "
9222 WARN_STRICT_OVERFLOW_COMPARISON);
9224 /* If const1 is negative we swap the sense of the comparison. */
9229 }
9236 {
9244 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9249 /* (-a) CMP (-b) -> b CMP a */
9256 {
9257 REAL_VALUE_TYPE cst;
9260 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9267 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9268 /* a CMP (-0) -> a CMP 0 */
9273 /* x != NaN is always true, other ops are always false. */
9276 {
9279 }
9281 /* Fold comparisons against infinity. */
9283 {
9287 }
9288 }
9290 /* If this is a comparison of a real constant with a PLUS_EXPR
9291 or a MINUS_EXPR of a real constant, we can convert it into a
9292 comparison with a revised real constant as long as no overflow
9293 occurs when unsafe_math_optimizations are enabled. */
9305 /* Likewise, we can simplify a comparison of a real constant with
9306 a MINUS_EXPR whose first operand is also a real constant, i.e.
9307 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9308 floating-point types only if -fassociative-math is set. */
9319 /* Fold comparisons against built-in math functions. */
9321 && flag_unsafe_math_optimizations
9323 {
9327 {
9331 }
9332 }
9333 }
9337 {
9338 /* If we are widening one operand of an integer comparison,
9339 see if the other operand is similarly being widened. Perhaps we
9340 can do the comparison in the narrower type. */
9345 /* Or if we are changing signedness. */
9349 }
9351 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9352 constant, we can simplify it. */
9357 {
9361 }
9363 /* Simplify comparison of something with itself. (For IEEE
9364 floating-point, we can only do some of these simplifications.) */
9366 {
9368 {
9383 /* For NE, we can only do this simplification if integer
9384 or we don't honor IEEE floating point NaNs. */
9388 /* ... fall through ... */
9394 }
9395 }
9397 /* If we are comparing an expression that just has comparisons
9398 of two integer values, arithmetic expressions of those comparisons,
9399 and constants, we can simplify it. There are only three cases
9400 to check: the two values can either be equal, the first can be
9401 greater, or the second can be greater. Fold the expression for
9402 those three values. Since each value must be 0 or 1, we have
9403 eight possibilities, each of which corresponds to the constant 0
9404 or 1 or one of the six possible comparisons.
9406 This handles common cases like (a > b) == 0 but also handles
9407 expressions like ((x > y) - (y > x)) > 0, which supposedly
9408 occur in macroized code. */
9411 {
9416 /* Don't handle degenerate cases here; they should already
9417 have been handled anyway. */
9426 {
9430 /* We can't just pass T to eval_subst in case cval1 or cval2
9431 was the same as ARG1. */
9433 tree high_result
9437 arg1);
9438 tree equal_result
9442 arg1);
9443 tree low_result
9447 arg1);
9449 /* All three of these results should be 0 or 1. Confirm they are.
9450 Then use those values to select the proper code to use. */
9455 {
9456 /* Make a 3-bit mask with the high-order bit being the
9457 value for `>', the next for '=', and the low for '<'. */
9461 {
9463 /* Always false. */
9484 /* Always true. */
9486 }
9491 }
9492 }
9493 }
9495 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9496 into a single range test. */
9504 {
9508 }
9510 /* Fold ~X op ~Y as Y op X. */
9513 {
9518 }
9520 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9523 {
9529 }
9532 }
9535 /* Subroutine of fold_binary. Optimize complex multiplications of the
9536 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9537 argument EXPR represents the expression "z" of type TYPE. */
9539 static tree
9541 {
9546 {
9549 }
9551 {
9554 }
9555 else
9556 {
9560 }
9569 }
9572 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9573 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9574 guarantees that P and N have the same least significant log2(M) bits.
9575 N is not otherwise constrained. In particular, N is not normalized to
9576 0 <= N < M as is common. In general, the precise value of P is unknown.
9577 M is chosen as large as possible such that constant N can be determined.
9579 Returns M and sets *RESIDUE to N. */
9581 static unsigned HOST_WIDE_INT
9583 {
9590 {
9593 {
9595 tree offset;
9603 {
9606 else
9607 /* We don't handle more complicated offset expressions. */
9609 }
9610 }
9614 }
9616 {
9629 {
9632 }
9634 {
9637 {
9640 /* Compute the greatest power-of-2 divisor of op1. */
9644 /* If align is non-zero and less than *modulus, replace
9645 *modulus with align., If align is 0, then either op1 is 0
9646 or the greatest power-of-2 divisor of op1 doesn't fit in an
9647 unsigned HOST_WIDE_INT. In either case, no additional
9648 constraint is imposed. */
9653 }
9654 }
9655 }
9657 /* If we get here, we were unable to determine anything useful about the
9658 expression. */
9660 }
9663 /* Fold a binary expression of code CODE and type TYPE with operands
9664 OP0 and OP1. Return the folded expression if folding is
9665 successful. Otherwise, return NULL_TREE. */
9667 tree
9669 {
9683 /* Strip any conversions that don't change the mode. This is
9684 safe for every expression, except for a comparison expression
9685 because its signedness is derived from its operands. So, in
9686 the latter case, only strip conversions that don't change the
9687 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9688 preserved.
9690 Note that this is done as an internal manipulation within the
9691 constant folder, in order to find the simplest representation
9692 of the arguments so that their form can be studied. In any
9693 cases, the appropriate type conversions should be put back in
9694 the tree that will get out of the constant folder. */
9697 {
9700 }
9701 else
9702 {
9705 }
9707 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9708 constant but we can't do arithmetic on them. */
9715 {
9717 {
9718 /* Make sure type and arg0 have the same saturating flag. */
9722 }
9725 else
9729 {
9733 }
9734 }
9736 /* If this is a commutative operation, and ARG0 is a constant, move it
9737 to ARG1 to reduce the number of tests below. */
9742 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9744 First check for cases where an arithmetic operation is applied to a
9745 compound, conditional, or comparison operation. Push the arithmetic
9746 operation inside the compound or conditional to see if any folding
9747 can then be done. Convert comparison to conditional for this purpose.
9748 The also optimizes non-constant cases that used to be done in
9749 expand_expr.
9751 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9752 one of the operands is a comparison and the other is a comparison, a
9753 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9754 code below would make the expression more complex. Change it to a
9755 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9756 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9768 {
9772 boolean_type_node,
9780 }
9784 {
9790 op1));
9799 {
9805 }
9808 {
9814 }
9815 }
9818 {
9821 /* 0 +p index -> (type)index */
9825 /* PTR +p 0 -> PTR */
9829 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9836 /* index +p PTR -> PTR +p index */
9843 /* (PTR +p B) +p A -> PTR +p (B + A) */
9845 {
9846 tree inner;
9858 }
9860 /* PTR_CST +p CST -> CST1 */
9864 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9865 of the array. Loop optimizer sometimes produce this type of
9866 expressions. */
9868 {
9872 }
9878 /* A + (-B) -> A - B */
9883 /* (-A) + B -> B - A */
9891 {
9892 /* Convert ~A + 1 to -A. */
9898 /* ~X + X is -1. */
9901 {
9906 {
9909 }
9910 }
9912 /* X + ~X is -1. */
9915 {
9920 {
9923 }
9924 }
9926 /* X + (X / CST) * -CST is X % CST. */
9931 {
9939 }
9940 }
9942 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9943 same or one. Make sure type is not saturating.
9944 fold_plusminus_mult_expr will re-associate. */
9949 {
9953 }
9956 {
9960 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9961 with a constant, and the two constants have no bits in common,
9962 we should treat this as a BIT_IOR_EXPR since this may produce more
9963 simplifications. */
9971 {
9974 }
9976 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9977 (plus (plus (mult) (mult)) (foo)) so that we can
9978 take advantage of the factoring cases below. */
9983 {
9989 else
10011 parg1)));
10012 }
10013 }
10014 else
10015 {
10016 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10020 /* Likewise if the operands are reversed. */
10024 /* Convert X + -C into X - C. */
10027 {
10033 }
10035 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10036 to __complex__ ( x, y ). This is not the same for SNaNs or
10037 if signed zeros are involved. */
10041 {
10048 {
10052 {
10058 }
10060 {
10066 }
10067 }
10068 }
10076 /* Convert x+x into x*2.0. */
10082 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10083 We associate floats only if the user has specified
10084 -fassociative-math. */
10088 {
10093 {
10094 tree tree0;
10097 }
10098 }
10099 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10100 We associate floats only if the user has specified
10101 -fassociative-math. */
10105 {
10110 {
10111 tree tree0;
10114 }
10115 }
10116 }
10118 bit_rotate:
10119 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10120 is a rotate of A by C1 bits. */
10121 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10122 is a rotate of A by B bits. */
10123 {
10125 tree rtype;
10134 /* Only create rotates in complete modes. Other cases are not
10135 expanded properly. */
10137 {
10156 {
10164 TYPE_PRECISION
10169 ? LROTATE_EXPR
10172 }
10174 {
10182 TYPE_PRECISION
10187 ? LROTATE_EXPR
10190 }
10191 }
10192 }
10194 associate:
10195 /* In most languages, can't associate operations on floats through
10196 parentheses. Rather than remember where the parentheses were, we
10197 don't associate floats at all, unless the user has specified
10198 -fassociative-math.
10199 And, we need to make sure type is not saturating. */
10203 {
10207 /* Split both trees into variables, constants, and literals. Then
10208 associate each group together, the constants with literals,
10209 then the result with variables. This increases the chances of
10210 literals being recombined later and of generating relocatable
10211 expressions for the sum of a constant and literal. */
10216 /* Only do something if we found more than two objects. Otherwise,
10217 nothing has changed and we risk infinite recursion. */
10222 {
10223 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10232 /* Preserve the MINUS_EXPR if the negative part of the literal is
10233 greater than the positive part. Otherwise, the multiplicative
10234 folding code (i.e extract_muldiv) may be fooled in case
10235 unsigned constants are subtracted, like in the following
10236 example: ((X*2 + 4) - 8U)/2. */
10238 {
10242 {
10246 }
10247 else
10248 {
10252 }
10253 }
10255 {
10260 else
10261 {
10267 }
10268 }
10273 }
10274 }
10280 /* Pointer simplifications for subtraction, simple reassociations. */
10282 {
10283 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10286 {
10294 }
10295 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming
10296 PTR0 - PTR1 simplifies. */
10298 {
10305 }
10306 }
10308 /* A - (-B) -> A + B */
10312 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10321 /* Convert -A - 1 to ~A. */
10330 /* Convert -1 - A to ~A. */
10336 /* X - (X / CST) * CST is X % CST. */
10349 {
10355 /* Fold A - (A & B) into ~B & A. */
10358 {
10360 {
10365 }
10367 {
10372 }
10373 }
10375 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10376 any power of 2 minus 1. */
10381 {
10387 {
10391 }
10392 }
10393 }
10395 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10399 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10400 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10401 (-ARG1 + ARG0) reduces to -ARG1. */
10405 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10406 __complex__ ( x, -y ). This is not the same for SNaNs or if
10407 signed zeros are involved. */
10411 {
10418 {
10422 {
10424 arg1r ? arg1r
10429 }
10431 {
10435 arg1i ? arg1i
10438 }
10439 }
10440 }
10442 /* Fold &x - &x. This can happen from &x.foo - &x.
10443 This is unsafe for certain floats even in non-IEEE formats.
10444 In IEEE, it is unsafe because it does wrong for NaNs.
10445 Also note that operand_equal_p is always false if an operand
10446 is volatile. */
10452 /* A - B -> A + (-B) if B is easily negatable. */
10454 /* Avoid negating constants if that would change overflow
10455 behavior. */
10460 /* Avoid this transformation if B is a positive REAL_CST. */
10464 {
10466 /* If the original subtraction is signed and did not overflow
10467 so does the new addition if the negation of arg1 does not
10468 overflow (which we know for constants only). */
10476 }
10478 /* Try folding difference of addresses. */
10479 {
10480 HOST_WIDE_INT diff;
10486 }
10488 /* Fold &a[i] - &a[j] to i-j. */
10493 {
10498 {
10506 }
10507 }
10515 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10516 same or one. Make sure type is not saturating.
10517 fold_plusminus_mult_expr will re-associate. */
10522 {
10526 }
10533 {
10538 /* Transform x * -1 into -x. Make sure to do the negation
10539 on the original operand with conversions not stripped
10540 because we can only strip non-sign-changing conversions. */
10543 }
10545 /* (-A) * (-B) -> A * B. */
10556 {
10557 /* Transform x * -C into -x * C if x is easily negatable. */
10566 /* (a * (1 << b)) is (a << b) */
10576 /* (A + A) * C -> A * 2 * C */
10591 {
10594 "occur when simplifying "
10596 WARN_STRICT_OVERFLOW_MISC);
10598 }
10600 /* Optimize z * conj(z) for integer complex numbers. */
10607 }
10608 else
10609 {
10610 /* Maybe fold x * 0 to 0. The expressions aren't the same
10611 when x is NaN, since x * 0 is also NaN. Nor are they the
10612 same in modes with signed zeros, since multiplying a
10613 negative value by 0 gives -0, not +0. */
10618 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10623 /* Transform x * -1.0 into -x. */
10628 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10629 the result for floating point types due to rounding so it is applied
10630 only if -fassociative-math was specify. */
10635 {
10641 }
10643 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10645 {
10648 {
10651 }
10652 }
10654 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10655 This is not the same for NaNs or if signed zeros are
10656 involved. */
10662 {
10674 }
10676 /* Optimize z * conj(z) for floating point complex numbers.
10677 Guarded by flag_unsafe_math_optimizations as non-finite
10678 imaginary components don't produce scalar results. */
10689 {
10693 /* Optimizations of root(...)*root(...). */
10695 {
10700 /* Optimize sqrt(x)*sqrt(x) as x. */
10706 /* Optimize root(x)*root(y) as root(x*y). */
10710 }
10712 /* Optimize expN(x)*expN(y) as expN(x+y). */
10714 {
10720 }
10722 /* Optimizations of pow(...)*pow(...). */
10726 {
10732 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10734 {
10738 }
10740 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10742 {
10746 }
10747 }
10749 /* Optimize tan(x)*cos(x) as sin(x). */
10758 {
10763 }
10765 /* Optimize x*pow(x,c) as pow(x,c+1). */
10769 {
10775 {
10777 REAL_VALUE_TYPE c;
10778 tree arg;
10784 }
10785 }
10787 /* Optimize pow(x,c)*x as pow(x,c+1). */
10791 {
10797 {
10799 REAL_VALUE_TYPE c;
10800 tree arg;
10806 }
10807 }
10809 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10812 {
10816 {
10819 }
10820 }
10821 }
10822 }
10826 bit_ior:
10834 /* ~X | X is -1. */
10837 {
10841 }
10843 /* X | ~X is -1. */
10846 {
10850 }
10852 /* Canonicalize (X & C1) | C2. */
10856 {
10864 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10869 {
10873 }
10874 else
10875 {
10879 }
10881 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10886 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10887 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10888 mode which allows further optimizations. */
10898 {
10899 unsigned HOST_WIDE_INT mask
10903 {
10907 }
10908 }
10915 arg1);
10916 }
10918 /* (X & Y) | Y is (X, Y). */
10922 /* (X & Y) | X is (Y, X). */
10927 /* X | (X & Y) is (Y, X). */
10932 /* X | (Y & X) is (Y, X). */
10942 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10944 This results in more efficient code for machines without a NAND
10945 instruction. Combine will canonicalize to the first form
10946 which will allow use of NAND instructions provided by the
10947 backend if they exist. */
10950 {
10957 }
10959 /* See if this can be simplified into a rotate first. If that
10960 is unsuccessful continue in the association code. */
10971 /* ~X ^ X is -1. */
10974 {
10978 }
10980 /* X ^ ~X is -1. */
10983 {
10987 }
10989 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10990 with a constant, and the two constants have no bits in common,
10991 we should treat this as a BIT_IOR_EXPR since this may produce more
10992 simplifications. */
11000 {
11003 }
11005 /* (X | Y) ^ X -> Y & ~ X*/
11008 {
11011 arg1);
11015 }
11017 /* (Y | X) ^ X -> Y & ~ X*/
11020 {
11023 arg1);
11027 }
11029 /* X ^ (X | Y) -> Y & ~ X*/
11032 {
11035 arg0);
11039 }
11041 /* X ^ (Y | X) -> Y & ~ X*/
11044 {
11047 arg0);
11051 }
11053 /* Convert ~X ^ ~Y to X ^ Y. */
11060 /* Convert ~X ^ C to X ^ ~C. */
11067 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11074 /* Fold (X & Y) ^ Y as ~X & Y. */
11077 {
11082 }
11083 /* Fold (X & Y) ^ X as ~Y & X. */
11087 {
11092 }
11093 /* Fold X ^ (X & Y) as X & ~Y. */
11096 {
11101 }
11102 /* Fold X ^ (Y & X) as ~Y & X. */
11106 {
11111 }
11113 /* See if this can be simplified into a rotate first. If that
11114 is unsuccessful continue in the association code. */
11125 /* ~X & X is always zero. */
11130 /* X & ~X is always zero. */
11135 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11139 {
11147 }
11149 /* (X | Y) & Y is (X, Y). */
11153 /* (X | Y) & X is (Y, X). */
11158 /* X & (X | Y) is (Y, X). */
11163 /* X & (Y | X) is (Y, X). */
11169 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11173 {
11179 }
11180 /* Fold ~X & 1 as (X & 1) == 0. */
11183 {
11189 }
11191 /* Fold (X ^ Y) & Y as ~X & Y. */
11194 {
11199 }
11200 /* Fold (X ^ Y) & X as ~Y & X. */
11204 {
11209 }
11210 /* Fold X & (X ^ Y) as X & ~Y. */
11213 {
11218 }
11219 /* Fold X & (Y ^ X) as ~Y & X. */
11223 {
11228 }
11233 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11236 {
11237 unsigned int prec
11244 }
11246 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11248 This results in more efficient code for machines without a NOR
11249 instruction. Combine will canonicalize to the first form
11250 which will allow use of NOR instructions provided by the
11251 backend if they exist. */
11254 {
11261 }
11263 /* If arg0 is derived from the address of an object or function, we may
11264 be able to fold this expression using the object or function's
11265 alignment. */
11267 {
11273 /* This works because modulus is a power of 2. If this weren't the
11274 case, we'd have to replace it by its greatest power-of-2
11275 divisor: modulus & -modulus. */
11278 }
11280 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11281 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11282 if the new mask might be further optimized. */
11291 {
11293 unsigned HOST_WIDE_INT mask
11303 {
11306 /* See if more bits can be proven as zero because of
11307 zero extension. */
11310 {
11315 {
11317 /* See if we can shorten the right shift. */
11320 }
11321 }
11325 /* For arithmetic shift if sign bit could be set, zerobits
11326 can contain actually sign bits, so no transformation is
11327 possible, unless MASK masks them all away. In that
11328 case the shift needs to be converted into logical shift. */
11331 {
11334 else
11336 }
11337 }
11339 /* ((X << 16) & 0xff00) is (X, 0). */
11345 {
11348 /* Only do the transformation if NEWMASK is some integer
11349 mode's mask. */
11356 {
11358 {
11364 }
11365 else
11369 newmask));
11370 }
11371 }
11372 }
11377 /* Don't touch a floating-point divide by zero unless the mode
11378 of the constant can represent infinity. */
11384 /* Optimize A / A to 1.0 if we don't care about
11385 NaNs or Infinities. Skip the transformation
11386 for non-real operands. */
11391 {
11395 }
11397 /* The complex version of the above A / A optimization. */
11400 {
11404 {
11406 /* omit_two_operands will call fold_convert for us. */
11408 }
11409 }
11411 /* (-A) / (-B) -> A / B */
11421 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11426 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11431 /* If ARG1 is a constant, we can convert this to a multiply by the
11432 reciprocal. This does not have the same rounding properties,
11433 so only do this if -freciprocal-math. We can actually
11434 always safely do it if ARG1 is a power of two, but it's hard to
11435 tell if it is or not in a portable manner. */
11437 {
11442 /* Find the reciprocal if optimizing and the result is exact. */
11444 {
11445 REAL_VALUE_TYPE r;
11448 {
11452 }
11453 }
11454 }
11455 /* Convert A/B/C to A/(B*C). */
11462 /* Convert A/(B/C) to (A/B)*C. */
11470 /* Convert C1/(X*C2) into (C1/C2)/X. */
11475 {
11481 }
11484 {
11488 /* Optimize sin(x)/cos(x) as tan(x). */
11494 {
11499 }
11501 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11507 {
11511 {
11515 }
11516 }
11518 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11519 NaNs or Infinities. */
11523 {
11530 {
11535 }
11536 }
11538 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11539 NaNs or Infinities. */
11543 {
11550 {
11554 {
11558 tmp);
11559 }
11560 }
11561 }
11563 /* Optimize pow(x,c)/x as pow(x,c-1). */
11567 {
11573 {
11575 REAL_VALUE_TYPE c;
11576 tree arg;
11582 }
11583 }
11585 /* Optimize a/root(b/c) into a*root(c/b). */
11587 {
11591 {
11600 }
11601 }
11603 /* Optimize x/expN(y) into x*expN(-y). */
11605 {
11610 }
11612 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11616 {
11623 }
11624 }
11629 /* Simplify A / (B << N) where A and B are positive and B is
11630 a power of 2, to A >> (N + log2(B)). */
11635 {
11638 {
11645 WARN_STRICT_OVERFLOW_MISC);
11651 }
11652 }
11654 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11655 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11661 /* Fall thru */
11670 /* X / -1 is -X. */
11677 /* Convert -A / -B to A / B when the type is signed and overflow is
11678 undefined. */
11682 {
11685 "when distributing negation across "
11687 WARN_STRICT_OVERFLOW_MISC);
11691 }
11695 {
11698 "when distributing negation across "
11700 WARN_STRICT_OVERFLOW_MISC);
11704 }
11706 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11707 operation, EXACT_DIV_EXPR.
11709 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11710 At one time others generated faster code, it's not clear if they do
11711 after the last round to changes to the DIV code in expmed.c. */
11720 {
11724 WARN_STRICT_OVERFLOW_MISC);
11726 }
11734 /* X % 1 is always zero, but be sure to preserve any side
11735 effects in X. */
11739 /* X % 0, return X % 0 unchanged so that we can get the
11740 proper warnings and errors. */
11744 /* 0 % X is always zero, but be sure to preserve any side
11745 effects in X. Place this after checking for X == 0. */
11749 /* X % -1 is zero. */
11756 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11757 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11762 {
11764 /* Also optimize A % (C << N) where C is a power of 2,
11765 to A & ((C << N) - 1). */
11770 {
11775 "occur when simplifying "
11777 WARN_STRICT_OVERFLOW_MISC);
11781 }
11782 }
11784 /* X % -C is the same as X % C. */
11791 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11796 /* X % -Y is the same as X % Y. */
11807 {
11811 WARN_STRICT_OVERFLOW_MISC);
11813 }
11824 /* Optimize -1 >> x for arithmetic right shifts. */
11828 /* ... fall through ... */
11831 shift:
11837 /* Since negative shift count is not well-defined,
11838 don't try to compute it in the compiler. */
11842 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11847 {
11851 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11852 being well defined. */
11854 {
11859 else
11861 }
11865 }
11867 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11868 into x & ((unsigned)-1 >> c) for unsigned types. */
11876 {
11879 tree lshift;
11880 tree arg00;
11883 {
11890 }
11891 }
11893 /* Rewrite an LROTATE_EXPR by a constant into an
11894 RROTATE_EXPR by a new constant. */
11896 {
11901 }
11903 /* If we have a rotate of a bit operation with the rotate count and
11904 the second operand of the bit operation both constant,
11905 permute the two operations. */
11917 /* Two consecutive rotates adding up to the precision of the
11918 type can be ignored. */
11929 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11930 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11931 if the latter can be further optimized. */
11936 {
11939 arg1);
11942 arg1);
11946 }
11974 /* Note that the operands of this must be ints
11975 and their values must be 0 or 1.
11976 ("true" is a fixed value perhaps depending on the language.) */
11977 /* If first arg is constant zero, return it. */
11981 /* If either arg is constant true, drop it. */
11985 /* Preserve sequence points. */
11988 /* If second arg is constant zero, result is zero, but first arg
11989 must be evaluated. */
11992 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11993 case will be handled here. */
11997 /* !X && X is always false. */
12001 /* X && !X is always false. */
12006 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12007 means A >= Y && A != MAX, but in this case we know that
12008 A < X <= MAX. */
12012 {
12020 }
12022 truth_andor:
12023 /* We only do these simplifications if we are optimizing. */
12027 /* Check for things like (A || B) && (A || C). We can convert this
12028 to A || (B && C). Note that either operator can be any of the four
12029 truth and/or operations and the transformation will still be
12030 valid. Also note that we only care about order for the
12031 ANDIF and ORIF operators. If B contains side effects, this
12032 might change the truth-value of A. */
12039 {
12059 /* This case if tricky because we must either have commutative
12060 operators or else A10 must not have side-effects. */
12066 a01);
12067 }
12069 /* See if we can build a range comparison. */
12073 /* Check for the possibility of merging component references. If our
12074 lhs is another similar operation, try to merge its rhs with our
12075 rhs. Then try to merge our lhs and rhs. */
12087 /* Note that the operands of this must be ints
12088 and their values must be 0 or true.
12089 ("true" is a fixed value perhaps depending on the language.) */
12090 /* If first arg is constant true, return it. */
12094 /* If either arg is constant zero, drop it. */
12098 /* Preserve sequence points. */
12101 /* If second arg is constant true, result is true, but we must
12102 evaluate first arg. */
12105 /* Likewise for first arg, but note this only occurs here for
12106 TRUTH_OR_EXPR. */
12110 /* !X || X is always true. */
12114 /* X || !X is always true. */
12122 /* If the second arg is constant zero, drop it. */
12125 /* If the second arg is constant true, this is a logical inversion. */
12127 {
12128 /* Only call invert_truthvalue if operand is a truth value. */
12131 else
12134 }
12135 /* Identical arguments cancel to zero. */
12139 /* !X ^ X is always true. */
12144 /* X ^ !X is always true. */
12157 /* bool_var != 0 becomes bool_var. */
12162 /* bool_var == 1 becomes bool_var. */
12167 /* bool_var != 1 becomes !bool_var. */
12172 /* bool_var == 0 becomes !bool_var. */
12177 /* If this is an equality comparison of the address of two non-weak,
12178 unaliased symbols neither of which are extern (since we do not
12179 have access to attributes for externs), then we know the result. */
12192 {
12193 /* We know that we're looking at the address of two
12194 non-weak, unaliased, static _DECL nodes.
12196 It is both wasteful and incorrect to call operand_equal_p
12197 to compare the two ADDR_EXPR nodes. It is wasteful in that
12198 all we need to do is test pointer equality for the arguments
12199 to the two ADDR_EXPR nodes. It is incorrect to use
12200 operand_equal_p as that function is NOT equivalent to a
12201 C equality test. It can in fact return false for two
12202 objects which would test as equal using the C equality
12203 operator. */
12207 type);
12208 }
12210 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12211 a MINUS_EXPR of a constant, we can convert it into a comparison with
12212 a revised constant as long as no overflow occurs. */
12224 /* Similarly for a NEGATE_EXPR. */
12232 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12241 /* Transform comparisons of the form X +- C CMP X. */
12247 {
12254 else
12257 }
12259 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12260 for !=. Don't do this for ordered comparisons due to overflow. */
12266 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12271 /* If this is an EQ or NE comparison with zero and ARG0 is
12272 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12273 two operations, but the latter can be done in one less insn
12274 on machines that have only two-operand insns or on which a
12275 constant cannot be the first operand. */
12278 {
12283 {
12290 }
12293 {
12300 }
12301 }
12303 /* If this is an NE or EQ comparison of zero against the result of a
12304 signed MOD operation whose second operand is a power of 2, make
12305 the MOD operation unsigned since it is simpler and equivalent. */
12313 {
12323 }
12325 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12326 C1 is a valid shift constant, and C2 is a power of two, i.e.
12327 a single bit. */
12331 == INTEGER_CST
12334 {
12339 /* Check for a valid shift count. */
12342 {
12346 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12347 can be rewritten as (X & (C2 << C1)) != 0. */
12349 {
12353 }
12354 /* Otherwise, for signed (arithmetic) shifts,
12355 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12356 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12360 /* Otherwise, of unsigned (logical) shifts,
12361 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12362 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12363 else
12367 arg000);
12368 }
12369 }
12371 /* If this is an NE comparison of zero with an AND of one, remove the
12372 comparison since the AND will give the correct value. */
12379 /* If we have (A & C) == C where C is a power of 2, convert this into
12380 (A & C) != 0. Similarly for NE_EXPR. */
12386 integer_zero_node));
12388 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12389 bit, then fold the expression into A < 0 or A >= 0. */
12394 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12395 Similarly for NE_EXPR. */
12399 {
12408 }
12410 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12411 Similarly for NE_EXPR. */
12415 {
12422 }
12424 /* If this is a comparison of a field, we may be able to simplify it. */
12427 /* Handle the constant case even without -O
12428 to make sure the warnings are given. */
12430 {
12434 }
12436 /* Optimize comparisons of strlen vs zero to a compare of the
12437 first character of the string vs zero. To wit,
12438 strlen(ptr) == 0 => *ptr == 0
12439 strlen(ptr) != 0 => *ptr != 0
12440 Other cases should reduce to one of these two (or a constant)
12441 due to the return value of strlen being unsigned. */
12444 {
12452 {
12456 }
12457 }
12459 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12460 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12464 {
12471 {
12473 {
12476 }
12479 }
12480 }
12482 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12488 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12493 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12500 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12508 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12509 (X & C) == 0 when C is a single bit. */
12514 {
12520 }
12522 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12523 constant C is a power of two, i.e. a single bit. */
12530 {
12534 }
12536 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12537 when is C is a power of two, i.e. a single bit. */
12544 {
12550 }
12554 {
12557 }
12559 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12566 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12569 {
12581 arg01),
12589 arg01),
12597 arg00),
12605 arg00),
12607 }
12611 {
12618 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12619 operand_equal_p guarantees no side-effects so we don't need
12620 to use omit_one_operand on Z. */
12630 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12637 arg10);
12638 }
12640 /* Attempt to simplify equality/inequality comparisons of complex
12641 values. Only lower the comparison if the result is known or
12642 can be simplified to a single scalar comparison. */
12647 {
12652 {
12655 }
12656 else
12657 {
12660 }
12663 {
12666 }
12667 else
12668 {
12671 }
12675 {
12677 {
12682 }
12683 else
12684 {
12689 }
12690 }
12694 {
12696 {
12701 }
12702 else
12703 {
12708 }
12709 }
12710 }
12722 /* Transform comparisons of the form X +- C CMP X. */
12729 {
12736 else
12739 /* (X - c) > X becomes false. */
12743 {
12747 "occur when assuming that (X - c) > X "
12749 WARN_STRICT_OVERFLOW_ALL);
12751 }
12753 /* Likewise (X + c) < X becomes false. */
12757 {
12761 "occur when assuming that "
12763 WARN_STRICT_OVERFLOW_ALL);
12765 }
12767 /* Convert (X - c) <= X to true. */
12772 {
12776 "occur when assuming that "
12778 WARN_STRICT_OVERFLOW_ALL);
12780 }
12782 /* Convert (X + c) >= X to true. */
12787 {
12791 "occur when assuming that "
12793 WARN_STRICT_OVERFLOW_ALL);
12795 }
12798 {
12799 /* Convert X + c > X and X - c < X to true for integers. */
12803 {
12806 "not occur when assuming that "
12808 WARN_STRICT_OVERFLOW_ALL);
12810 }
12815 {
12818 "not occur when assuming that "
12820 WARN_STRICT_OVERFLOW_ALL);
12822 }
12824 /* Convert X + c <= X and X - c >= X to false for integers. */
12828 {
12831 "not occur when assuming that "
12833 WARN_STRICT_OVERFLOW_ALL);
12835 }
12840 {
12843 "not occur when assuming that "
12845 WARN_STRICT_OVERFLOW_ALL);
12847 }
12848 }
12849 }
12851 /* Comparisons with the highest or lowest possible integer of
12852 the specified precision will have known values. */
12853 {
12860 {
12861 HOST_WIDE_INT signed_max_hi;
12866 {
12873 {
12877 }
12878 else
12879 {
12883 }
12884 }
12885 else
12886 {
12895 {
12898 }
12899 else
12900 {
12903 }
12904 }
12909 {
12922 /* The GE_EXPR and LT_EXPR cases above are not normally
12923 reached because of previous transformations. */
12927 }
12929 == max_hi
12932 {
12938 arg1);
12944 arg1);
12947 }
12949 == min_hi
12952 {
12967 }
12969 == min_hi
12972 {
12977 arg1);
12982 arg1);
12985 }
12990 /* We will flip the signedness of the comparison operator
12991 associated with the mode of arg1, so the sign bit is
12992 specified by this mode. Check that arg1 is the signed
12993 max associated with this sign bit. */
12995 /* signed_type does not work on pointer types. */
12997 {
12998 /* The following case also applies to X < signed_max+1
12999 and X >= signed_max+1 because previous transformations. */
13001 {
13002 tree st;
13007 }
13008 }
13009 }
13010 }
13012 /* If we are comparing an ABS_EXPR with a constant, we can
13013 convert all the cases into explicit comparisons, but they may
13014 well not be faster than doing the ABS and one comparison.
13015 But ABS (X) <= C is a range comparison, which becomes a subtraction
13016 and a comparison, and is probably faster. */
13030 /* Convert ABS_EXPR<x> >= 0 to true. */
13037 {
13040 "when simplifying comparison of "
13042 WARN_STRICT_OVERFLOW_CONDITIONAL);
13044 }
13046 /* Convert ABS_EXPR<x> < 0 to false. */
13051 {
13054 "when simplifying comparison of "
13056 WARN_STRICT_OVERFLOW_CONDITIONAL);
13058 }
13060 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13061 and similarly for >= into !=. */
13076 return
13095 {
13099 }
13101 /* If the first operand is NaN, the result is constant. */
13105 {
13107 ? integer_zero_node
13110 }
13112 /* If the second operand is NaN, the result is constant. */
13116 {
13118 ? integer_zero_node
13121 }
13123 /* Simplify unordered comparison of something with itself. */
13129 && !flag_trapping_math
13133 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13134 {
13145 }
13150 /* When pedantic, a compound expression can be neither an lvalue
13151 nor an integer constant expression. */
13154 /* Don't let (0, 0) be null pointer constant. */
13168 /* An ASSERT_EXPR should never be passed to fold_binary. */
13174 }
13176 /* Callback for walk_tree, looking for LABEL_EXPR.
13177 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13178 Do not check the sub-tree of GOTO_EXPR. */
13180 static tree
13184 {
13186 {
13191 /* no break */
13194 }
13195 }
13197 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13198 accessible from outside the sub-tree. Returns NULL_TREE if no
13199 addressable label is found. */
13201 static bool
13203 {
13205 }
13207 /* Fold a ternary expression of code CODE and type TYPE with operands
13208 OP0, OP1, and OP2. Return the folded expression if folding is
13209 successful. Otherwise, return NULL_TREE. */
13211 tree
13213 {
13214 tree tem;
13221 /* Strip any conversions that don't change the mode. This is safe
13222 for every expression, except for a comparison expression because
13223 its signedness is derived from its operands. So, in the latter
13224 case, only strip conversions that don't change the signedness.
13226 Note that this is done as an internal manipulation within the
13227 constant folder, in order to find the simplest representation of
13228 the arguments so that their form can be studied. In any cases,
13229 the appropriate type conversions should be put back in the tree
13230 that will get out of the constant folder. */
13232 {
13235 }
13238 {
13241 }
13244 {
13248 {
13254 }
13258 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13259 so all simple results must be passed through pedantic_non_lvalue. */
13261 {
13264 /* Only optimize constant conditions when the selected branch
13265 has the same type as the COND_EXPR. This avoids optimizing
13266 away "c ? x : throw", where the throw has a void type.
13267 Avoid throwing away that operand which contains label. */
13274 }
13278 /* If we have A op B ? A : C, we may be able to convert this to a
13279 simpler expression, depending on the operation and the values
13280 of B and C. Signed zeros prevent all of these transformations,
13281 for reasons given above each one.
13283 Also try swapping the arguments and inverting the conditional. */
13288 {
13292 }
13296 op2,
13299 {
13302 {
13306 }
13307 }
13309 /* If the second operand is simpler than the third, swap them
13310 since that produces better jump optimization results. */
13313 {
13314 /* See if this can be inverted. If it can't, possibly because
13315 it was a floating-point inequality comparison, don't do
13316 anything. */
13320 }
13322 /* Convert A ? 1 : 0 to simply A. */
13325 /* If we try to convert OP0 to our type, the
13326 call to fold will try to move the conversion inside
13327 a COND, which will recurse. In that case, the COND_EXPR
13328 is probably the best choice, so leave it alone. */
13332 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13333 over COND_EXPR in cases such as floating point comparisons. */
13340 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13345 {
13346 /* sign_bit_p only checks ARG1 bits within A's precision.
13347 If <sign bit of A> has wider type than A, bits outside
13348 of A's precision in <sign bit of A> need to be checked.
13349 If they are all 0, this optimization needs to be done
13350 in unsigned A's type, if they are all 1 in signed A's type,
13351 otherwise this can't be done. */
13356 {
13358 HOST_WIDE_INT mask_hi;
13360 tree tem_type;
13368 {
13372 }
13373 else
13374 {
13378 }
13380 {
13384 }
13385 else
13391 {
13394 }
13397 {
13400 }
13401 else
13403 }
13410 arg1)));
13411 }
13413 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13414 already handled above. */
13419 {
13428 }
13430 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13431 is probably obsolete because the first operand should be a
13432 truth value (that's why we have the two cases above), but let's
13433 leave it in until we can confirm this for all front-ends. */
13444 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13450 arg1);
13452 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13456 {
13457 /* Only perform transformation if ARG0 is easily inverted. */
13462 arg1);
13463 }
13465 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13469 {
13470 /* Only perform transformation if ARG0 is easily inverted. */
13475 op2);
13476 }
13478 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13484 op2);
13489 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13490 of fold_ternary on them. */
13497 {
13506 {
13511 else
13512 {
13514 tree value;
13518 }
13523 else
13525 }
13526 }
13528 /* A bit-field-ref that referenced the full argument can be stripped. */
13539 }
13541 /* Perform constant folding and related simplification of EXPR.
13542 The related simplifications include x*1 => x, x*0 => 0, etc.,
13543 and application of the associative law.
13544 NOP_EXPR conversions may be removed freely (as long as we
13545 are careful not to change the type of the overall expression).
13546 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13547 but we can constant-fold them if they have constant operands. */
13549 #ifdef ENABLE_FOLD_CHECKING
13550 # define fold(x) fold_1 (x)
13552 static
13553 #endif
13554 tree
13556 {
13560 tree tem;
13562 /* Return right away if a constant. */
13566 /* CALL_EXPR-like objects with variable numbers of operands are
13567 treated specially. */
13569 {
13571 {
13574 }
13576 }
13579 {
13584 {
13602 }
13603 }
13606 {
13608 {
13615 {
13620 /* Find a matching index by means of a binary search. */
13622 {
13638 else
13640 }
13641 }
13644 }
13652 }
13654 #ifdef ENABLE_FOLD_CHECKING
13655 #undef fold
13661 /* When --enable-checking=fold, compute a digest of expr before
13662 and after actual fold call to see if fold did not accidentally
13663 change original expr. */
13665 tree
13667 {
13668 tree ret;
13671 htab_t ht;
13690 }
13692 void
13694 {
13697 htab_t ht;
13707 }
13709 static void
13711 {
13713 }
13715 static void
13717 {
13723 recursive_label:
13737 {
13738 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13742 }
13749 {
13750 /* Allow these fields to be modified. */
13751 tree tmp;
13759 {
13762 }
13763 }
13772 {
13775 {
13789 }
13793 {
13806 }
13823 {
13829 }
13834 {
13838 }
13849 {
13852 }
13862 }
13863 }
13865 /* Helper function for outputting the checksum of a tree T. When
13866 debugging with gdb, you can "define mynext" to be "next" followed
13867 by "call debug_fold_checksum (op0)", then just trace down till the
13868 outputs differ. */
13870 void
13872 {
13887 }
13889 #endif
13891 /* Fold a unary tree expression with code CODE of type TYPE with an
13892 operand OP0. Return a folded expression if successful. Otherwise,
13893 return a tree expression with code CODE of type TYPE with an
13894 operand OP0. */
13896 tree
13898 {
13899 tree tem;
13900 #ifdef ENABLE_FOLD_CHECKING
13903 htab_t ht;
13910 #endif
13916 #ifdef ENABLE_FOLD_CHECKING
13924 #endif
13926 }
13928 /* Fold a binary tree expression with code CODE of type TYPE with
13929 operands OP0 and OP1. Return a folded expression if successful.
13930 Otherwise, return a tree expression with code CODE of type TYPE
13931 with operands OP0 and OP1. */
13933 tree
13935 MEM_STAT_DECL)
13936 {
13937 tree tem;
13938 #ifdef ENABLE_FOLD_CHECKING
13944 htab_t ht;
13956 #endif
13962 #ifdef ENABLE_FOLD_CHECKING
13978 #endif
13980 }
13982 /* Fold a ternary tree expression with code CODE of type TYPE with
13983 operands OP0, OP1, and OP2. Return a folded expression if
13984 successful. Otherwise, return a tree expression with code CODE of
13985 type TYPE with operands OP0, OP1, and OP2. */
13987 tree
13989 MEM_STAT_DECL)
13990 {
13991 tree tem;
13992 #ifdef ENABLE_FOLD_CHECKING
14000 htab_t ht;
14017 #endif
14024 #ifdef ENABLE_FOLD_CHECKING
14048 #endif
14050 }
14052 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14053 arguments in ARGARRAY, and a null static chain.
14054 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14055 of type TYPE from the given operands as constructed by build_call_array. */
14057 tree
14059 {
14060 tree tem;
14061 #ifdef ENABLE_FOLD_CHECKING
14067 htab_t ht;
14081 #endif
14085 #ifdef ENABLE_FOLD_CHECKING
14102 #endif
14104 }
14106 /* Perform constant folding and related simplification of initializer
14107 expression EXPR. These behave identically to "fold_buildN" but ignore
14108 potential run-time traps and exceptions that fold must preserve. */
14110 #define START_FOLD_INIT \
14111 int saved_signaling_nans = flag_signaling_nans;\
14112 int saved_trapping_math = flag_trapping_math;\
14113 int saved_rounding_math = flag_rounding_math;\
14114 int saved_trapv = flag_trapv;\
14115 int saved_folding_initializer = folding_initializer;\
14116 flag_signaling_nans = 0;\
14117 flag_trapping_math = 0;\
14118 flag_rounding_math = 0;\
14119 flag_trapv = 0;\
14120 folding_initializer = 1;
14122 #define END_FOLD_INIT \
14123 flag_signaling_nans = saved_signaling_nans;\
14124 flag_trapping_math = saved_trapping_math;\
14125 flag_rounding_math = saved_rounding_math;\
14126 flag_trapv = saved_trapv;\
14127 folding_initializer = saved_folding_initializer;
14129 tree
14131 {
14132 tree result;
14133 START_FOLD_INIT;
14137 END_FOLD_INIT;
14139 }
14141 tree
14143 {
14144 tree result;
14145 START_FOLD_INIT;
14149 END_FOLD_INIT;
14151 }
14153 tree
14155 tree op2)
14156 {
14157 tree result;
14158 START_FOLD_INIT;
14162 END_FOLD_INIT;
14164 }
14166 tree
14169 {
14170 tree result;
14171 START_FOLD_INIT;
14175 END_FOLD_INIT;
14177 }
14179 #undef START_FOLD_INIT
14180 #undef END_FOLD_INIT
14182 /* Determine if first argument is a multiple of second argument. Return 0 if
14183 it is not, or we cannot easily determined it to be.
14185 An example of the sort of thing we care about (at this point; this routine
14186 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14187 fold cases do now) is discovering that
14189 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14191 is a multiple of
14193 SAVE_EXPR (J * 8)
14195 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14197 This code also handles discovering that
14199 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14201 is a multiple of 8 so we don't have to worry about dealing with a
14202 possible remainder.
14204 Note that we *look* inside a SAVE_EXPR only to determine how it was
14205 calculated; it is not safe for fold to do much of anything else with the
14206 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14207 at run time. For example, the latter example above *cannot* be implemented
14208 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14209 evaluation time of the original SAVE_EXPR is not necessarily the same at
14210 the time the new expression is evaluated. The only optimization of this
14211 sort that would be valid is changing
14213 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14215 divided by 8 to
14217 SAVE_EXPR (I) * SAVE_EXPR (J)
14219 (where the same SAVE_EXPR (J) is used in the original and the
14220 transformed version). */
14222 int
14224 {
14232 {
14234 /* Bitwise and provides a power of two multiple. If the mask is
14235 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14238 /* FALLTHRU */
14251 {
14255 /* const_binop may not detect overflow correctly,
14256 so check for it explicitly here. */
14262 size_one_node,
14266 }
14270 /* Can't handle conversions from non-integral or wider integral type. */
14276 /* .. fall through ... */
14293 }
14294 }
14296 /* Return true if CODE or TYPE is known to be non-negative. */
14298 static bool
14300 {
14303 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14304 have a signed:1 type (where the value is -1 and 0). */
14307 }
14309 /* Return true if (CODE OP0) is known to be non-negative. If the return
14310 value is based on the assumption that signed overflow is undefined,
14311 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14312 *STRICT_OVERFLOW_P. */
14314 bool
14317 {
14322 {
14324 /* We can't return 1 if flag_wrapv is set because
14325 ABS_EXPR<INT_MIN> = INT_MIN. */
14334 strict_overflow_p);
14336 CASE_CONVERT:
14337 {
14342 {
14345 strict_overflow_p);
14347 {
14351 strict_overflow_p);
14352 }
14353 }
14355 {
14358 strict_overflow_p);
14362 }
14363 }
14368 }
14370 /* We don't know sign of `t', so be conservative and return false. */
14372 }
14374 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14375 value is based on the assumption that signed overflow is undefined,
14376 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14377 *STRICT_OVERFLOW_P. */
14379 bool
14382 {
14387 {
14390 /* Pointers do not have a "sign". */
14395 {
14399 }
14401 /* Fallthru. */
14405 strict_overflow_p)
14407 strict_overflow_p));
14409 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14410 both unsigned and at least 2 bits shorter than the result. */
14414 {
14419 {
14423 }
14424 }
14429 {
14431 /* x * x without overflowing is always non-negative. */
14436 }
14438 /* Fallthru. */
14441 {
14442 /* x * x for floating point x is always non-negative. */
14446 strict_overflow_p)
14448 strict_overflow_p));
14449 }
14451 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14452 both unsigned and their total bits is shorter than the result. */
14456 {
14475 {
14485 }
14486 }
14492 strict_overflow_p)
14494 strict_overflow_p));
14505 strict_overflow_p)
14507 strict_overflow_p));
14514 strict_overflow_p);
14517 }
14519 /* We don't know sign of `t', so be conservative and return false. */
14521 }
14523 /* Return true if T is known to be non-negative. If the return
14524 value is based on the assumption that signed overflow is undefined,
14525 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14526 *STRICT_OVERFLOW_P. */
14528 bool
14530 {
14535 {
14547 strict_overflow_p)
14549 strict_overflow_p));
14553 }
14554 /* We don't know sign of `t', so be conservative and return false. */
14556 }
14558 /* Return true if T is known to be non-negative. If the return
14559 value is based on the assumption that signed overflow is undefined,
14560 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14561 *STRICT_OVERFLOW_P. */
14563 bool
14566 {
14569 {
14587 /* Always true. */
14591 /* sqrt(-0.0) is -0.0. */
14595 strict_overflow_p);
14628 /* True if the 1st argument is nonnegative. */
14630 strict_overflow_p);
14633 /* True if the 1st OR 2nd arguments are nonnegative. */
14635 strict_overflow_p)
14637 strict_overflow_p)));
14640 /* True if the 1st AND 2nd arguments are nonnegative. */
14642 strict_overflow_p)
14644 strict_overflow_p)));
14647 /* True if the 2nd argument is nonnegative. */
14649 strict_overflow_p);
14652 /* True if the 1st argument is nonnegative or the second
14653 argument is an even integer. */
14658 strict_overflow_p);
14661 /* True if the 1st argument is nonnegative or the second
14662 argument is an even integer valued real. */
14664 {
14665 REAL_VALUE_TYPE c;
14666 HOST_WIDE_INT n;
14671 {
14672 REAL_VALUE_TYPE cint;
14677 }
14678 }
14680 strict_overflow_p);
14684 }
14686 type);
14687 }
14689 /* Return true if T is known to be non-negative. If the return
14690 value is based on the assumption that signed overflow is undefined,
14691 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14692 *STRICT_OVERFLOW_P. */
14694 bool
14696 {
14702 {
14704 {
14708 /* If the initializer is non-void, then it's a normal expression
14709 that will be assigned to the slot. */
14713 /* Otherwise, the initializer sets the slot in some way. One common
14714 way is an assignment statement at the end of the initializer. */
14716 {
14724 else
14726 }
14730 strict_overflow_p);
14733 }
14736 {
14742 arg0,
14743 arg1,
14744 strict_overflow_p);
14745 }
14749 strict_overflow_p);
14752 strict_overflow_p);
14755 strict_overflow_p);
14760 }
14762 /* We don't know sign of `t', so be conservative and return false. */
14764 }
14766 /* Return true if T is known to be non-negative. If the return
14767 value is based on the assumption that signed overflow is undefined,
14768 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14769 *STRICT_OVERFLOW_P. */
14771 bool
14773 {
14780 {
14787 strict_overflow_p);
14793 strict_overflow_p);
14802 }
14805 {
14813 strict_overflow_p);
14818 strict_overflow_p);
14833 }
14834 }
14836 /* Return true if `t' is known to be non-negative. Handle warnings
14837 about undefined signed overflow. */
14839 bool
14841 {
14848 "determining that expression is always "
14850 WARN_STRICT_OVERFLOW_MISC);
14852 }
14855 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14856 For floating point we further ensure that T is not denormal.
14857 Similar logic is present in nonzero_address in rtlanal.h.
14859 If the return value is based on the assumption that signed overflow
14860 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14861 change *STRICT_OVERFLOW_P. */
14863 bool
14866 {
14868 {
14871 strict_overflow_p);
14874 {
14880 strict_overflow_p));
14881 }
14886 strict_overflow_p);
14890 }
14893 }
14895 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14896 For floating point we further ensure that T is not denormal.
14897 Similar logic is present in nonzero_address in rtlanal.h.
14899 If the return value is based on the assumption that signed overflow
14900 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14901 change *STRICT_OVERFLOW_P. */
14903 bool
14905 tree type ATTRIBUTE_UNUSED,
14906 tree op0,
14908 {
14911 {
14915 {
14916 /* With the presence of negative values it is hard
14917 to say something. */
14924 /* One of operands must be positive and the other non-negative. */
14925 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14926 overflows, on a twos-complement machine the sum of two
14927 nonnegative numbers can never be zero. */
14929 strict_overflow_p)
14931 strict_overflow_p));
14932 }
14937 {
14939 strict_overflow_p)
14941 strict_overflow_p))
14942 {
14945 }
14946 }
14955 {
14958 }
14965 {
14969 /* When both operands are nonzero, then MAX must be too. */
14971 strict_overflow_p))
14974 /* MAX where operand 0 is positive is positive. */
14976 strict_overflow_p);
14977 }
14978 /* MAX where operand 1 is positive is positive. */
14983 {
14987 }
14992 strict_overflow_p)
14994 strict_overflow_p));
14998 }
15001 }
15003 /* Return true when T is an address and is known to be nonzero.
15004 For floating point we further ensure that T is not denormal.
15005 Similar logic is present in nonzero_address in rtlanal.h.
15007 If the return value is based on the assumption that signed overflow
15008 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15009 change *STRICT_OVERFLOW_P. */
15011 bool
15013 {
15016 {
15021 {
15027 /* Weak declarations may link to NULL. */
15031 /* Constants are never weak. */
15036 }
15044 {
15048 }
15053 }
15055 }
15057 /* Return true when T is an address and is known to be nonzero.
15058 For floating point we further ensure that T is not denormal.
15059 Similar logic is present in nonzero_address in rtlanal.h.
15061 If the return value is based on the assumption that signed overflow
15062 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15063 change *STRICT_OVERFLOW_P. */
15065 bool
15067 {
15071 /* Doing something useful for floating point would need more work. */
15077 {
15080 strict_overflow_p);
15086 strict_overflow_p);
15094 }
15097 {
15100 strict_overflow_p);
15108 strict_overflow_p);
15125 strict_overflow_p);
15129 strict_overflow_p);
15136 }
15138 }
15140 /* Return true when T is an address and is known to be nonzero.
15141 Handle warnings about undefined signed overflow. */
15143 bool
15145 {
15152 "determining that expression is always "
15154 WARN_STRICT_OVERFLOW_MISC);
15156 }
15158 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15159 attempt to fold the expression to a constant without modifying TYPE,
15160 OP0 or OP1.
15162 If the expression could be simplified to a constant, then return
15163 the constant. If the expression would not be simplified to a
15164 constant, then return NULL_TREE. */
15166 tree
15168 {
15171 }
15173 /* Given the components of a unary expression CODE, TYPE and OP0,
15174 attempt to fold the expression to a constant without modifying
15175 TYPE or OP0.
15177 If the expression could be simplified to a constant, then return
15178 the constant. If the expression would not be simplified to a
15179 constant, then return NULL_TREE. */
15181 tree
15183 {
15186 }
15188 /* If EXP represents referencing an element in a constant string
15189 (either via pointer arithmetic or array indexing), return the
15190 tree representing the value accessed, otherwise return NULL. */
15192 tree
15194 {
15198 {
15200 tree index;
15201 tree string;
15205 else
15206 {
15210 /* Optimize the special-case of a zero lower bound.
15212 We convert the low_bound to sizetype to avoid some problems
15213 with constant folding. (E.g. suppose the lower bound is 1,
15214 and its mode is QI. Without the conversion,l (ARRAY
15215 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15216 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15221 }
15234 }
15236 }
15238 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15239 an integer constant, real, or fixed-point constant.
15241 TYPE is the type of the result. */
15243 static tree
15245 {
15249 {
15251 {
15253 HOST_WIDE_INT high;
15261 }
15268 {
15269 FIXED_VALUE_TYPE f;
15274 /* Propagate overflow flags. */
15276 {
15279 }
15283 }
15287 }
15290 }
15292 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15293 an integer constant or real constant.
15295 TYPE is the type of the result. */
15297 tree
15299 {
15303 {
15305 /* If the value is unsigned, then the absolute value is
15306 the same as the ordinary value. */
15309 /* Similarly, if the value is non-negative. */
15312 /* If the value is negative, then the absolute value is
15313 its negation. */
15314 else
15315 {
15317 HOST_WIDE_INT high;
15323 }
15329 else
15335 }
15338 }
15340 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15341 constant. TYPE is the type of the result. */
15343 static tree
15345 {
15355 }
15357 /* Given CODE, a relational operator, the target type, TYPE and two
15358 constant operands OP0 and OP1, return the result of the
15359 relational operation. If the result is not a compile time
15360 constant, then return NULL_TREE. */
15362 static tree
15364 {
15367 /* From here on, the only cases we handle are when the result is
15368 known to be a constant. */
15371 {
15375 /* Handle the cases where either operand is a NaN. */
15377 {
15379 {
15407 }
15410 }
15413 }
15416 {
15420 }
15422 /* Handle equality/inequality of complex constants. */
15424 {
15435 else
15437 }
15439 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15441 To compute GT, swap the arguments and do LT.
15442 To compute GE, do LT and invert the result.
15443 To compute LE, swap the arguments, do LT and invert the result.
15444 To compute NE, do EQ and invert the result.
15446 Therefore, the code below must handle only EQ and LT. */
15449 {
15454 }
15456 /* Note that it is safe to invert for real values here because we
15457 have already handled the one case that it matters. */
15461 {
15464 }
15466 /* Compute a result for LT or EQ if args permit;
15467 Otherwise return T. */
15469 {
15474 else
15476 }
15477 else
15483 }
15485 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15486 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15487 itself. */
15489 tree
15491 {
15492 /* If the expression does not have side effects then we don't have to wrap
15493 it with a cleanup point expression. */
15497 /* If the expression is a return, check to see if the expression inside the
15498 return has no side effects or the right hand side of the modify expression
15499 inside the return. If either don't have side effects set we don't need to
15500 wrap the expression in a cleanup point expression. Note we don't check the
15501 left hand side of the modify because it should always be a return decl. */
15503 {
15510 }
15513 }
15515 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15516 of an indirection through OP0, or NULL_TREE if no simplification is
15517 possible. */
15519 tree
15521 {
15523 tree subtype;
15531 {
15534 /* *&CONST_DECL -> to the value of the const decl. */
15537 /* *&p => p; make sure to handle *&"str"[cst] here. */
15539 {
15543 else
15545 }
15546 /* *(foo *)&fooarray => fooarray[0] */
15549 {
15555 }
15556 /* *(foo *)&complexfoo => __real__ complexfoo */
15560 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15563 {
15567 }
15568 }
15570 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15573 {
15576 tree op00type;
15583 {
15594 }
15595 }
15598 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15601 {
15604 tree op00type;
15611 {
15615 }
15616 }
15618 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15621 {
15622 tree type_domain;
15629 }
15632 }
15634 /* Builds an expression for an indirection through T, simplifying some
15635 cases. */
15637 tree
15639 {
15645 else
15647 }
15649 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15651 tree
15653 {
15658 else
15660 }
15662 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15663 whose result is ignored. The type of the returned tree need not be
15664 the same as the original expression. */
15666 tree
15668 {
15674 {
15685 else
15691 {
15707 }
15712 }
15713 }
15715 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15716 This can only be applied to objects of a sizetype. */
15718 tree
15720 {
15727 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15728 have to do anything. Only do this when we are not given a const,
15729 because in that case, this check is more expensive than just
15730 doing it. */
15732 {
15737 }
15739 /* If divisor is a power of two, simplify this to bit manipulation. */
15741 {
15743 {
15756 {
15757 high++;
15760 }
15764 }
15765 else
15766 {
15767 tree t;
15773 }
15774 }
15775 else
15776 {
15781 }
15784 }
15786 /* Likewise, but round down. */
15788 tree
15790 {
15797 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15798 have to do anything. Only do this when we are not given a const,
15799 because in that case, this check is more expensive than just
15800 doing it. */
15802 {
15807 }
15809 /* If divisor is a power of two, simplify this to bit manipulation. */
15811 {
15812 tree t;
15816 }
15817 else
15818 {
15823 }
15826 }
15828 /* Returns the pointer to the base of the object addressed by EXP and
15829 extracts the information about the offset of the access, storing it
15830 to PBITPOS and POFFSET. */
15832 static tree
15835 {
15836 tree core;
15839 HOST_WIDE_INT bitsize;
15842 {
15847 }
15848 else
15849 {
15853 }
15856 }
15858 /* Returns true if addresses of E1 and E2 differ by a constant, false
15859 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15861 bool
15863 {
15877 {
15887 }
15889 {
15890 /* If only one of the offsets is non-constant, the difference cannot
15891 be a constant. */
15893 }
15894 else
15899 }
15901 /* Simplify the floating point expression EXP when the sign of the
15902 result is not significant. Return NULL_TREE if no simplification
15903 is possible. */
15905 tree
15907 {
15911 {
15946 {
15949 {
15951 /* Strip copysign function call, return the 1st argument. */
15957 /* Strip sign ops from the argument of "odd" math functions. */
15959 {
15963 }
15965 }
15966 }
15971 }
15973 }