| blob | e6769a650a8836b3af76c343cca3b5a0a2241de4 |
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
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 };
125 tree);
146 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
147 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
148 and SUM1. Then this yields nonzero if overflow occurred during the
149 addition.
151 Overflow occurs if A and B have the same sign, but A and SUM differ in
152 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
153 sign. */
154 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
155 \f
156 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
157 We do that by representing the two-word integer in 4 words, with only
158 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
159 number. The value of the word is LOWPART + HIGHPART * BASE. */
161 #define LOWPART(x) \
162 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
163 #define HIGHPART(x) \
164 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
165 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
167 /* Unpack a two-word integer into 4 words.
168 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
169 WORDS points to the array of HOST_WIDE_INTs. */
171 static void
173 {
178 }
180 /* Pack an array of 4 words into a two-word integer.
181 WORDS points to the array of words.
182 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
184 static void
187 {
190 }
191 \f
192 /* Force the double-word integer L1, H1 to be within the range of the
193 integer type TYPE. Stores the properly truncated and sign-extended
194 double-word integer in *LV, *HV. Returns true if the operation
195 overflows, that is, argument and result are different. */
197 int
200 {
209 else
212 /* Size types *are* sign extended. */
217 /* First clear all bits that are beyond the type's precision. */
219 ;
222 else
223 {
227 }
229 /* Then do sign extension if necessary. */
235 {
236 /* Sign extend top half? */
240 }
242 {
245 }
246 else
247 {
248 /* Sign extend bottom half? */
250 {
253 }
254 }
259 /* If the value didn't fit, signal overflow. */
261 }
263 /* We force the double-int HIGH:LOW to the range of the type TYPE by
264 sign or zero extending it.
265 OVERFLOWABLE indicates if we are interested
266 in overflow of the value, when >0 we are only interested in signed
267 overflow, for <0 we are interested in any overflow. OVERFLOWED
268 indicates whether overflow has already occurred. CONST_OVERFLOWED
269 indicates whether constant overflow has already occurred. We force
270 T's value to be within range of T's type (by setting to 0 or 1 all
271 the bits outside the type's range). We set TREE_OVERFLOWED if,
272 OVERFLOWED is nonzero,
273 or OVERFLOWABLE is >0 and signed overflow occurs
274 or OVERFLOWABLE is <0 and any overflow occurs
275 We return a new tree node for the extended double-int. The node
276 is shared if no overflow flags are set. */
278 tree
282 {
286 /* Size types *are* sign extended. */
293 /* If we need to set overflow flags, return a new unshared node. */
295 {
299 {
306 }
307 }
309 /* Else build a shared node. */
311 }
312 \f
313 /* Add two doubleword integers with doubleword result.
314 Return nonzero if the operation overflows according to UNSIGNED_P.
315 Each argument is given as two `HOST_WIDE_INT' pieces.
316 One argument is L1 and H1; the other, L2 and H2.
317 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
319 int
324 {
326 HOST_WIDE_INT h;
336 else
338 }
340 /* Negate a doubleword integer with doubleword result.
341 Return nonzero if the operation overflows, assuming it's signed.
342 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
343 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
345 int
348 {
350 {
354 }
355 else
356 {
360 }
361 }
362 \f
363 /* Multiply two doubleword integers with doubleword result.
364 Return nonzero if the operation overflows according to UNSIGNED_P.
365 Each argument is given as two `HOST_WIDE_INT' pieces.
366 One argument is L1 and H1; the other, L2 and H2.
367 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
369 int
374 {
389 {
392 {
394 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
396 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
400 }
402 }
407 /* Unsigned overflow is immediate. */
411 /* Check for signed overflow by calculating the signed representation of the
412 top half of the result; it should agree with the low half's sign bit. */
414 {
417 }
419 {
422 }
424 }
425 \f
426 /* Shift the doubleword integer in L1, H1 left by COUNT places
427 keeping only PREC bits of result.
428 Shift right if COUNT is negative.
429 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
430 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
432 void
436 {
440 {
443 }
449 {
450 /* Shifting by the host word size is undefined according to the
451 ANSI standard, so we must handle this as a special case. */
454 }
456 {
459 }
460 else
461 {
465 }
467 /* Sign extend all bits that are beyond the precision. */
475 ;
477 {
480 }
481 else
482 {
486 }
487 }
489 /* Shift the doubleword integer in L1, H1 right by COUNT places
490 keeping only PREC bits of result. COUNT must be positive.
491 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
492 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
494 void
499 {
502 signmask = (arith
510 {
511 /* Shifting by the host word size is undefined according to the
512 ANSI standard, so we must handle this as a special case. */
515 }
517 {
520 }
521 else
522 {
526 }
528 /* Zero / sign extend all bits that are beyond the precision. */
531 {
534 }
536 ;
538 {
541 }
542 else
543 {
547 }
548 }
549 \f
550 /* Rotate the doubleword integer in L1, H1 left by COUNT places
551 keeping only PREC bits of result.
552 Rotate right if COUNT is negative.
553 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
555 void
559 {
571 }
573 /* Rotate the doubleword integer in L1, H1 left by COUNT places
574 keeping only PREC bits of result. COUNT must be positive.
575 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
577 void
581 {
593 }
594 \f
595 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
596 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
597 CODE is a tree code for a kind of division, one of
598 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
599 or EXACT_DIV_EXPR
600 It controls how the quotient is rounded to an integer.
601 Return nonzero if the operation overflows.
602 UNS nonzero says do unsigned division. */
604 int
607 HOST_WIDE_INT hnum_orig,
609 HOST_WIDE_INT hden_orig,
613 {
629 /* Calculate quotient sign and convert operands to unsigned. */
631 {
633 {
635 /* (minimum integer) / (-1) is the only overflow case. */
639 }
641 {
644 }
645 }
650 /* This unsigned division rounds toward zero. */
653 }
657 /* hden != 0 already checked. */
662 }
672 /* Special code for when the divisor < BASE. */
674 {
675 /* hnum != 0 already checked. */
677 {
681 }
682 }
683 else
684 {
685 /* Full double precision division,
686 with thanks to Don Knuth's "Seminumerical Algorithms". */
690 /* Find the highest nonzero divisor digit. */
693 {
696 }
698 /* Insure that the first digit of the divisor is at least BASE/2.
699 This is required by the quotient digit estimation algorithm. */
706 {
710 }
715 {
720 }
721 }
725 /* Main loop */
727 {
728 /* Guess the next quotient digit, quo_est, by dividing the first
729 two remaining dividend digits by the high order quotient digit.
730 quo_est is never low and is at most 2 high. */
737 else
740 /* Refine quo_est so it's usually correct, and at most one high. */
745 quo_est--;
747 /* Try QUO_EST as the quotient digit, by multiplying the
748 divisor by QUO_EST and subtracting from the remaining dividend.
749 Keep in mind that QUO_EST is the I - 1st digit. */
753 {
759 }
761 /* If quo_est was high by one, then num[i] went negative and
762 we need to correct things. */
764 {
765 quo_est--;
768 {
772 }
775 }
777 /* Store the quotient digit. */
779 }
780 }
784 finish_up:
785 /* If result is negative, make it so. */
789 /* Compute trial remainder: rem = num - (quo * den) */
795 {
804 {
805 /* quo = quo - 1; */
808 }
809 else
816 {
819 }
820 else
826 {
832 /* Get absolute values. */
838 /* If (2 * abs (lrem) >= abs (lden)) */
847 {
849 /* quo = quo - 1; */
852 else
853 /* quo = quo + 1; */
856 }
857 else
859 }
864 }
866 /* Compute true remainder: rem = num - (quo * den) */
871 }
873 /* If ARG2 divides ARG1 with zero remainder, carries out the division
874 of type CODE and returns the quotient.
875 Otherwise returns NULL_TREE. */
877 static tree
879 {
889 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
890 &obj[some_exotic_number]. */
892 {
896 type);
897 }
898 else
909 }
910 \f
911 /* This is nonzero if we should defer warnings about undefined
912 overflow. This facility exists because these warnings are a
913 special case. The code to estimate loop iterations does not want
914 to issue any warnings, since it works with expressions which do not
915 occur in user code. Various bits of cleanup code call fold(), but
916 only use the result if it has certain characteristics (e.g., is a
917 constant); that code only wants to issue a warning if the result is
918 used. */
922 /* If a warning about undefined overflow is deferred, this is the
923 warning. Note that this may cause us to turn two warnings into
924 one, but that is fine since it is sufficient to only give one
925 warning per expression. */
929 /* If a warning about undefined overflow is deferred, this is the
930 level at which the warning should be emitted. */
934 /* Start deferring overflow warnings. We could use a stack here to
935 permit nested calls, but at present it is not necessary. */
937 void
939 {
941 }
943 /* Stop deferring overflow warnings. If there is a pending warning,
944 and ISSUE is true, then issue the warning if appropriate. STMT is
945 the statement with which the warning should be associated (used for
946 location information); STMT may be NULL. CODE is the level of the
947 warning--a warn_strict_overflow_code value. This function will use
948 the smaller of CODE and the deferred code when deciding whether to
949 issue the warning. CODE may be zero to mean to always use the
950 deferred code. */
952 void
954 {
956 location_t locus;
961 {
967 }
978 /* Use the smallest code level when deciding to issue the
979 warning. */
988 else
991 }
993 /* Stop deferring overflow warnings, ignoring any deferred
994 warnings. */
996 void
998 {
1000 }
1002 /* Whether we are deferring overflow warnings. */
1004 bool
1006 {
1008 }
1010 /* This is called when we fold something based on the fact that signed
1011 overflow is undefined. */
1013 static void
1015 {
1017 {
1020 {
1023 }
1024 }
1027 }
1028 \f
1029 /* Return true if the built-in mathematical function specified by CODE
1030 is odd, i.e. -f(x) == f(-x). */
1032 static bool
1034 {
1036 {
1070 }
1072 }
1074 /* Check whether we may negate an integer constant T without causing
1075 overflow. */
1077 bool
1079 {
1082 tree type;
1092 {
1097 }
1098 else
1103 }
1105 /* Determine whether an expression T can be cheaply negated using
1106 the function negate_expr without introducing undefined overflow. */
1108 static bool
1110 {
1111 tree type;
1120 {
1125 /* Check that -CST will not overflow type. */
1151 /* -(A + B) -> (-B) - A. */
1156 /* -(A + B) -> (-A) - B. */
1160 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1170 /* Fall through. */
1183 /* In general we can't negate A / B, because if A is INT_MIN and
1184 B is 1, we may turn this into INT_MIN / -1 which is undefined
1185 and actually traps on some architectures. But if overflow is
1186 undefined, we can negate, because - (INT_MIN / 1) is an
1187 overflow. */
1195 /* Negate -((double)float) as (double)(-float). */
1197 {
1201 }
1205 /* Negate -f(x) as f(-x). */
1211 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1213 {
1219 }
1224 }
1226 }
1228 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1229 simplification is possible.
1230 If negate_expr_p would return true for T, NULL_TREE will never be
1231 returned. */
1233 static tree
1235 {
1237 tree tem;
1240 {
1241 /* Convert - (~A) to A + 1. */
1257 /* Two's complement FP formats, such as c4x, may overflow. */
1267 {
1276 }
1298 {
1299 /* -(A + B) -> (-B) - A. */
1303 {
1307 }
1309 /* -(A + B) -> (-A) - B. */
1311 {
1315 }
1316 }
1320 /* - (A - B) -> B - A */
1332 /* Fall through. */
1336 {
1345 }
1353 /* In general we can't negate A / B, because if A is INT_MIN and
1354 B is 1, we may turn this into INT_MIN / -1 which is undefined
1355 and actually traps on some architectures. But if overflow is
1356 undefined, we can negate, because - (INT_MIN / 1) is an
1357 overflow. */
1359 {
1364 {
1371 }
1374 {
1381 }
1382 }
1386 /* Convert -((double)float) into (double)(-float). */
1388 {
1392 }
1396 /* Negate -f(x) as f(-x). */
1399 {
1405 }
1409 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1411 {
1416 {
1423 }
1424 }
1429 }
1432 }
1434 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1435 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1436 return NULL_TREE. */
1438 static tree
1440 {
1453 }
1454 \f
1455 /* Split a tree IN into a constant, literal and variable parts that could be
1456 combined with CODE to make IN. "constant" means an expression with
1457 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1458 commutative arithmetic operation. Store the constant part into *CONP,
1459 the literal in *LITP and return the variable part. If a part isn't
1460 present, set it to null. If the tree does not decompose in this way,
1461 return the entire tree as the variable part and the other parts as null.
1463 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1464 case, we negate an operand that was subtracted. Except if it is a
1465 literal for which we use *MINUS_LITP instead.
1467 If NEGATE_P is true, we are negating all of IN, again except a literal
1468 for which we use *MINUS_LITP instead.
1470 If IN is itself a literal or constant, return it as appropriate.
1472 Note that we do not guarantee that any of the three values will be the
1473 same type as IN, but they will have the same signedness and mode. */
1475 static tree
1478 {
1485 /* Strip any conversions that don't change the machine mode or signedness. */
1494 /* We can associate addition and subtraction together (even
1495 though the C standard doesn't say so) for integers because
1496 the value is not affected. For reals, the value might be
1497 affected, so we can't. */
1500 {
1506 /* First see if either of the operands is a literal, then a constant. */
1519 /* If we haven't dealt with either operand, this is not a case we can
1520 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1525 else
1528 /* Now do any needed negations. */
1535 }
1538 else
1542 {
1549 }
1552 }
1554 /* Re-associate trees split by the above function. T1 and T2 are either
1555 expressions to associate or null. Return the new expression, if any. If
1556 we build an operation, do it in TYPE and with CODE. */
1558 static tree
1560 {
1566 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1567 try to fold this since we will have infinite recursion. But do
1568 deal with any NEGATE_EXPRs. */
1571 {
1573 {
1582 }
1584 {
1587 }
1591 }
1595 }
1596 \f
1597 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1598 for use in int_const_binop, size_binop and size_diffop. */
1600 static bool
1602 {
1609 {
1618 }
1623 }
1626 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1627 to produce a new constant. Return NULL_TREE if we don't know how
1628 to evaluate CODE at compile-time.
1630 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1632 tree
1634 {
1638 HOST_WIDE_INT hi;
1640 HOST_WIDE_INT garbageh;
1641 tree t;
1644 int is_sizetype
1654 {
1670 /* It's unclear from the C standard whether shifts can overflow.
1671 The following code ignores overflow; perhaps a C standard
1672 interpretation ruling is needed. */
1701 /* This is a shortcut for a common special case. */
1706 {
1712 }
1714 /* ... fall through ... */
1720 {
1723 }
1726 {
1729 }
1736 /* This is a shortcut for a common special case. */
1741 {
1746 }
1748 /* ... fall through ... */
1766 else
1772 else
1778 }
1781 {
1784 /* Propagate overflow flags ourselves. */
1787 {
1790 }
1791 }
1792 else
1798 }
1800 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1801 constant. We assume ARG1 and ARG2 have the same data type, or at least
1802 are the same kind of constant and the same machine mode. Return zero if
1803 combining the constants is not allowed in the current operating mode.
1805 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1807 static tree
1809 {
1810 /* Sanity check for the recursive cases. */
1821 {
1823 REAL_VALUE_TYPE d1;
1824 REAL_VALUE_TYPE d2;
1825 REAL_VALUE_TYPE value;
1826 REAL_VALUE_TYPE result;
1830 /* The following codes are handled by real_arithmetic. */
1832 {
1843 }
1851 /* Don't perform operation if we honor signaling NaNs and
1852 either operand is a NaN. */
1857 /* Don't perform operation if it would raise a division
1858 by zero exception. */
1864 /* If either operand is a NaN, just return it. Otherwise, set up
1865 for floating-point trap; we return an overflow. */
1874 /* Don't constant fold this floating point operation if
1875 the result has overflowed and flag_trapping_math. */
1883 /* Don't constant fold this floating point operation if the
1884 result may dependent upon the run-time rounding mode and
1885 flag_rounding_math is set, or if GCC's software emulation
1886 is unable to accurately represent the result. */
1896 }
1899 {
1900 FIXED_VALUE_TYPE f1;
1901 FIXED_VALUE_TYPE f2;
1902 FIXED_VALUE_TYPE result;
1907 /* The following codes are handled by fixed_arithmetic. */
1909 {
1926 }
1933 /* Propagate overflow flags. */
1935 {
1938 }
1942 }
1945 {
1954 {
1965 notrunc);
1969 notrunc);
1973 {
1974 tree magsquared
1978 notrunc);
1979 tree t1
1983 notrunc);
1984 tree t2
1988 notrunc);
1995 }
2000 }
2004 }
2007 }
2009 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2010 indicates which particular sizetype to create. */
2012 tree
2014 {
2016 }
2017 \f
2018 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2019 is a tree code. The type of the result is taken from the operands.
2020 Both must be equivalent integer types, ala int_binop_types_match_p.
2021 If the operands are constant, so is the result. */
2023 tree
2025 {
2034 /* Handle the special case of two integer constants faster. */
2036 {
2037 /* And some specific cases even faster than that. */
2039 {
2044 }
2046 {
2049 }
2051 {
2054 }
2056 /* Handle general case of two integer constants. */
2058 }
2061 }
2063 /* Given two values, either both of sizetype or both of bitsizetype,
2064 compute the difference between the two values. Return the value
2065 in signed type corresponding to the type of the operands. */
2067 tree
2069 {
2071 tree ctype;
2076 /* If the type is already signed, just do the simple thing. */
2084 else
2087 /* If either operand is not a constant, do the conversions to the signed
2088 type and subtract. The hardware will do the right thing with any
2089 overflow in the subtraction. */
2094 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2095 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2096 overflow) and negate (which can't either). Special-case a result
2097 of zero while we're here. */
2102 else
2106 }
2107 \f
2108 /* A subroutine of fold_convert_const handling conversions of an
2109 INTEGER_CST to another integer type. */
2111 static tree
2113 {
2114 tree t;
2116 /* Given an integer constant, make new constant with new type,
2117 appropriately sign-extended or truncated. */
2120 /* Don't set the overflow when
2121 converting from a pointer, */
2123 /* or to a sizetype with same signedness
2124 and the precision is unchanged.
2125 ??? sizetype is always sign-extended,
2126 but its signedness depends on the
2127 frontend. Thus we see spurious overflows
2128 here if we do not check this. */
2143 }
2145 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2146 to an integer type. */
2148 static tree
2150 {
2152 tree t;
2154 /* The following code implements the floating point to integer
2155 conversion rules required by the Java Language Specification,
2156 that IEEE NaNs are mapped to zero and values that overflow
2157 the target precision saturate, i.e. values greater than
2158 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2159 are mapped to INT_MIN. These semantics are allowed by the
2160 C and C++ standards that simply state that the behavior of
2161 FP-to-integer conversion is unspecified upon overflow. */
2164 REAL_VALUE_TYPE r;
2168 {
2175 }
2177 /* If R is NaN, return zero and show we have an overflow. */
2179 {
2183 }
2185 /* See if R is less than the lower bound or greater than the
2186 upper bound. */
2189 {
2193 {
2197 }
2198 }
2201 {
2204 {
2207 {
2211 }
2212 }
2213 }
2221 }
2223 /* A subroutine of fold_convert_const handling conversions of a
2224 FIXED_CST to an integer type. */
2226 static tree
2228 {
2229 tree t;
2233 /* Right shift FIXED_CST to temp by fbit. */
2237 {
2242 /* Left shift temp to temp_trunc by fbit. */
2247 }
2248 else
2249 {
2254 }
2256 /* If FIXED_CST is negative, we need to round the value toward 0.
2257 By checking if the fractional bits are not zero to add 1 to temp. */
2260 {
2261 double_int one;
2265 }
2267 /* Given a fixed-point constant, make new constant with new type,
2268 appropriately sign-extended or truncated. */
2276 }
2278 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2279 to another floating point type. */
2281 static tree
2283 {
2284 REAL_VALUE_TYPE value;
2285 tree t;
2292 }
2294 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2295 to a floating point type. */
2297 static tree
2299 {
2300 REAL_VALUE_TYPE value;
2301 tree t;
2310 }
2312 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2313 to another fixed-point type. */
2315 static tree
2317 {
2318 FIXED_VALUE_TYPE value;
2319 tree t;
2326 /* Propagate overflow flags. */
2328 {
2331 }
2335 }
2337 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2338 to a fixed-point type. */
2340 static tree
2342 {
2343 FIXED_VALUE_TYPE value;
2344 tree t;
2353 /* Propagate overflow flags. */
2355 {
2358 }
2362 }
2364 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2365 to a fixed-point type. */
2367 static tree
2369 {
2370 FIXED_VALUE_TYPE value;
2371 tree t;
2379 /* Propagate overflow flags. */
2381 {
2384 }
2388 }
2390 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2391 type TYPE. If no simplification can be done return NULL_TREE. */
2393 static tree
2395 {
2401 {
2408 }
2410 {
2417 }
2419 {
2426 }
2428 }
2430 /* Construct a vector of zero elements of vector type TYPE. */
2432 static tree
2434 {
2445 }
2447 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2449 bool
2451 {
2466 {
2485 }
2486 }
2488 /* Convert expression ARG to type TYPE. Used by the middle-end for
2489 simple conversions in preference to calling the front-end's convert. */
2491 tree
2493 {
2495 tree tem;
2509 {
2514 {
2518 }
2523 {
2526 }
2533 {
2537 }
2539 {
2543 }
2545 {
2549 }
2552 {
2570 }
2575 {
2579 }
2582 {
2596 }
2600 {
2610 {
2614 {
2618 }
2626 }
2630 }
2648 }
2649 }
2650 \f
2651 /* Return false if expr can be assumed not to be an lvalue, true
2652 otherwise. */
2654 static bool
2656 {
2657 /* We only need to wrap lvalue tree codes. */
2659 {
2693 /* Assume the worst for front-end tree codes. */
2697 }
2700 }
2702 /* Return an expr equal to X but certainly not valid as an lvalue. */
2704 tree
2706 {
2707 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2708 us. */
2715 }
2717 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2718 Zero means allow extended lvalues. */
2722 /* When pedantic, return an expr equal to X but certainly not valid as a
2723 pedantic lvalue. Otherwise, return X. */
2725 static tree
2727 {
2730 else
2732 }
2733 \f
2734 /* Given a tree comparison code, return the code that is the logical inverse
2735 of the given code. It is not safe to do this for floating-point
2736 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2737 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2739 enum tree_code
2741 {
2746 {
2777 }
2778 }
2780 /* Similar, but return the comparison that results if the operands are
2781 swapped. This is safe for floating-point. */
2783 enum tree_code
2785 {
2787 {
2813 }
2814 }
2817 /* Convert a comparison tree code from an enum tree_code representation
2818 into a compcode bit-based encoding. This function is the inverse of
2819 compcode_to_comparison. */
2821 static enum comparison_code
2823 {
2825 {
2856 }
2857 }
2859 /* Convert a compcode bit-based encoding of a comparison operator back
2860 to GCC's enum tree_code representation. This function is the
2861 inverse of comparison_to_compcode. */
2863 static enum tree_code
2865 {
2867 {
2898 }
2899 }
2901 /* Return a tree for the comparison which is the combination of
2902 doing the AND or OR (depending on CODE) of the two operations LCODE
2903 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2904 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2905 if this makes the transformation invalid. */
2907 tree
2911 {
2918 {
2929 }
2932 {
2933 /* Eliminate unordered comparisons, as well as LTGT and ORD
2934 which are not used unless the mode has NaNs. */
2940 }
2942 {
2943 /* Check that the original operation and the optimized ones will trap
2944 under the same condition. */
2955 /* In a short-circuited boolean expression the LHS might be
2956 such that the RHS, if evaluated, will never trap. For
2957 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2958 if neither x nor y is NaN. (This is a mixed blessing: for
2959 example, the expression above will never trap, hence
2960 optimizing it to x < y would be invalid). */
2965 /* If the comparison was short-circuited, and only the RHS
2966 trapped, we may now generate a spurious trap. */
2971 /* If we changed the conditions that cause a trap, we lose. */
2974 }
2980 else
2983 }
2985 /* Return nonzero if CODE is a tree code that represents a truth value. */
2987 static int
2989 {
2994 }
2995 \f
2996 /* Return nonzero if two operands (typically of the same tree node)
2997 are necessarily equal. If either argument has side-effects this
2998 function returns zero. FLAGS modifies behavior as follows:
3000 If OEP_ONLY_CONST is set, only return nonzero for constants.
3001 This function tests whether the operands are indistinguishable;
3002 it does not test whether they are equal using C's == operation.
3003 The distinction is important for IEEE floating point, because
3004 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3005 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3007 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3008 even though it may hold multiple values during a function.
3009 This is because a GCC tree node guarantees that nothing else is
3010 executed between the evaluation of its "operands" (which may often
3011 be evaluated in arbitrary order). Hence if the operands themselves
3012 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3013 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3014 unset means assuming isochronic (or instantaneous) tree equivalence.
3015 Unless comparing arbitrary expression trees, such as from different
3016 statements, this flag can usually be left unset.
3018 If OEP_PURE_SAME is set, then pure functions with identical arguments
3019 are considered the same. It is used when the caller has other ways
3020 to ensure that global memory is unchanged in between. */
3022 int
3024 {
3025 /* If either is ERROR_MARK, they aren't equal. */
3029 /* Check equality of integer constants before bailing out due to
3030 precision differences. */
3034 /* If both types don't have the same signedness, then we can't consider
3035 them equal. We must check this before the STRIP_NOPS calls
3036 because they may change the signedness of the arguments. As pointers
3037 strictly don't have a signedness, require either two pointers or
3038 two non-pointers as well. */
3043 /* If both types don't have the same precision, then it is not safe
3044 to strip NOPs. */
3051 /* In case both args are comparisons but with different comparison
3052 code, try to swap the comparison operands of one arg to produce
3053 a match and compare that variant. */
3057 {
3065 }
3068 /* This is needed for conversions and for COMPONENT_REF.
3069 Might as well play it safe and always test this. */
3075 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3076 We don't care about side effects in that case because the SAVE_EXPR
3077 takes care of that for us. In all other cases, two expressions are
3078 equal if they have no side effects. If we have two identical
3079 expressions with side effects that should be treated the same due
3080 to the only side effects being identical SAVE_EXPR's, that will
3081 be detected in the recursive calls below. */
3087 /* Next handle constant cases, those for which we can return 1 even
3088 if ONLY_CONST is set. */
3091 {
3106 {
3107 /* If we do not distinguish between signed and unsigned zero,
3108 consider them equal. */
3111 }
3115 {
3121 {
3123 flags))
3127 }
3130 }
3134 flags)
3136 flags));
3149 }
3154 /* Define macros to test an operand from arg0 and arg1 for equality and a
3155 variant that allows null and views null as being different from any
3156 non-null value. In the latter case, if either is null, the both
3157 must be; otherwise, do the normal comparison. */
3158 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3159 TREE_OPERAND (arg1, N), flags)
3161 #define OP_SAME_WITH_NULL(N) \
3162 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3163 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3166 {
3168 /* Two conversions are equal only if signedness and modes match. */
3170 {
3171 CASE_CONVERT:
3179 }
3189 /* For commutative ops, allow the other order. */
3197 /* If either of the pointer (or reference) expressions we are
3198 dereferencing contain a side effect, these cannot be equal. */
3204 {
3214 /* Operands 2 and 3 may be null.
3215 Compare the array index by value if it is constant first as we
3216 may have different types but same value here. */
3225 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3226 may be NULL when we're called to compare MEM_EXPRs. */
3236 }
3240 {
3255 /* Otherwise take into account this is a commutative operation. */
3266 }
3270 {
3272 /* If the CALL_EXPRs call different functions, then they
3273 clearly can not be equal. */
3275 flags))
3278 {
3282 else
3286 }
3288 /* Now see if all the arguments are the same. */
3289 {
3300 /* If we get here and both argument lists are exhausted
3301 then the CALL_EXPRs are equal. */
3303 }
3306 }
3309 /* Consider __builtin_sqrt equal to sqrt. */
3317 }
3319 #undef OP_SAME
3320 #undef OP_SAME_WITH_NULL
3321 }
3322 \f
3323 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3324 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3326 When in doubt, return 0. */
3328 static int
3330 {
3342 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3343 and see if the inner values are the same. This removes any
3344 signedness comparison, which doesn't matter here. */
3351 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3352 actual comparison operand, ARG0.
3354 First throw away any conversions to wider types
3355 already present in the operands. */
3364 {
3367 /* Make sure shorter operand is extended the right way
3368 to match the longer operand. */
3374 }
3377 }
3378 \f
3379 /* See if ARG is an expression that is either a comparison or is performing
3380 arithmetic on comparisons. The comparisons must only be comparing
3381 two different values, which will be stored in *CVAL1 and *CVAL2; if
3382 they are nonzero it means that some operands have already been found.
3383 No variables may be used anywhere else in the expression except in the
3384 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3385 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3387 If this is true, return 1. Otherwise, return zero. */
3389 static int
3391 {
3395 /* We can handle some of the tcc_expression cases here. */
3405 {
3406 /* If we've already found a CVAL1 or CVAL2, this expression is
3407 two complex to handle. */
3413 }
3416 {
3439 /* First see if we can handle the first operand, then the second. For
3440 the second operand, we know *CVAL1 can't be zero. It must be that
3441 one side of the comparison is each of the values; test for the
3442 case where this isn't true by failing if the two operands
3443 are the same. */
3452 ;
3456 ;
3457 else
3461 ;
3465 ;
3466 else
3473 }
3474 }
3475 \f
3476 /* ARG is a tree that is known to contain just arithmetic operations and
3477 comparisons. Evaluate the operations in the tree substituting NEW0 for
3478 any occurrence of OLD0 as an operand of a comparison and likewise for
3479 NEW1 and OLD1. */
3481 static tree
3483 {
3488 /* We can handle some of the tcc_expression cases here. */
3496 {
3511 {
3528 }
3529 /* Fall through - ??? */
3532 {
3536 /* We need to check both for exact equality and tree equality. The
3537 former will be true if the operand has a side-effect. In that
3538 case, we know the operand occurred exactly once. */
3551 }
3555 }
3556 }
3557 \f
3558 /* Return a tree for the case when the result of an expression is RESULT
3559 converted to TYPE and OMITTED was previously an operand of the expression
3560 but is now not needed (e.g., we folded OMITTED * 0).
3562 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3563 the conversion of RESULT to TYPE. */
3565 tree
3567 {
3570 /* If the resulting operand is an empty statement, just return the omitted
3571 statement casted to void. */
3579 }
3581 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3583 static tree
3585 {
3588 /* If the resulting operand is an empty statement, just return the omitted
3589 statement casted to void. */
3597 }
3599 /* Return a tree for the case when the result of an expression is RESULT
3600 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3601 of the expression but are now not needed.
3603 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3604 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3605 evaluated before OMITTED2. Otherwise, if neither has side effects,
3606 just do the conversion of RESULT to TYPE. */
3608 tree
3610 {
3619 }
3621 \f
3622 /* Return a simplified tree node for the truth-negation of ARG. This
3623 never alters ARG itself. We assume that ARG is an operation that
3624 returns a truth value (0 or 1).
3626 FIXME: one would think we would fold the result, but it causes
3627 problems with the dominator optimizer. */
3629 tree
3631 {
3635 /* If this is a comparison, we can simply invert it, except for
3636 floating-point non-equality comparisons, in which case we just
3637 enclose a TRUTH_NOT_EXPR around what we have. */
3640 {
3643 && flag_trapping_math
3647 else
3648 {
3653 else
3656 }
3657 }
3660 {
3675 /* Here we can invert either operand. We invert the first operand
3676 unless the second operand is a TRUTH_NOT_EXPR in which case our
3677 result is the XOR of the first operand with the inside of the
3678 negation of the second operand. */
3683 else
3702 {
3705 /* A COND_EXPR may have a throw as one operand, which
3706 then has void type. Just leave void operands
3707 as they are. */
3713 }
3746 }
3749 }
3751 /* Return a simplified tree node for the truth-negation of ARG. This
3752 never alters ARG itself. We assume that ARG is an operation that
3753 returns a truth value (0 or 1).
3755 FIXME: one would think we would fold the result, but it causes
3756 problems with the dominator optimizer. */
3758 tree
3760 {
3761 tree tem;
3771 }
3773 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3774 operands are another bit-wise operation with a common input. If so,
3775 distribute the bit operations to save an operation and possibly two if
3776 constants are involved. For example, convert
3777 (A | B) & (A | C) into A | (B & C)
3778 Further simplification will occur if B and C are constants.
3780 If this optimization cannot be done, 0 will be returned. */
3782 static tree
3784 {
3785 tree common;
3795 {
3799 }
3801 {
3805 }
3807 {
3811 }
3813 {
3817 }
3818 else
3823 }
3825 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3826 with code CODE. This optimization is unsafe. */
3827 static tree
3829 {
3833 /* (A / C) +- (B / C) -> (A +- B) / C. */
3843 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3848 {
3860 }
3863 }
3864 \f
3865 /* Subroutine for fold_truthop: decode a field reference.
3867 If EXP is a comparison reference, we return the innermost reference.
3869 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3870 set to the starting bit number.
3872 If the innermost field can be completely contained in a mode-sized
3873 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3875 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3876 otherwise it is not changed.
3878 *PUNSIGNEDP is set to the signedness of the field.
3880 *PMASK is set to the mask used. This is either contained in a
3881 BIT_AND_EXPR or derived from the width of the field.
3883 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3885 Return 0 if this is not a component reference or is one that we can't
3886 do anything with. */
3888 static tree
3893 {
3897 tree unsigned_type;
3900 /* All the optimizations using this function assume integer fields.
3901 There are problems with FP fields since the type_for_size call
3902 below can fail for, e.g., XFmode. */
3906 /* We are interested in the bare arrangement of bits, so strip everything
3907 that doesn't affect the machine mode. However, record the type of the
3908 outermost expression if it may matter below. */
3915 {
3921 }
3930 /* If the number of bits in the reference is the same as the bitsize of
3931 the outer type, then the outer type gives the signedness. Otherwise
3932 (in case of a small bitfield) the signedness is unchanged. */
3936 /* Compute the mask to access the bitfield. */
3945 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3953 }
3955 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3956 represents the sign bit of EXP's type. If EXP represents a sign
3957 or zero extension, also test VAL against the unextended type.
3958 The return value is the (sub)expression whose sign bit is VAL,
3959 or NULL_TREE otherwise. */
3961 static tree
3963 {
3967 tree t;
3969 /* Tree EXP must have an integral type. */
3974 /* Tree VAL must be an integer constant. */
3981 {
3988 }
3989 else
3990 {
3997 }
3999 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4000 treat VAL as if it were unsigned. */
4005 /* Handle extension from a narrower type. */
4011 }
4013 /* Subroutine for fold_truthop: determine if an operand is simple enough
4014 to be evaluated unconditionally. */
4016 static int
4018 {
4019 /* Strip any conversions that don't change the machine mode. */
4028 /* Don't regard global variables as simple. They may be
4029 allocated in ways unknown to the compiler (shared memory,
4030 #pragma weak, etc). */
4033 /* Loading a static variable is unduly expensive, but global
4034 registers aren't expensive. */
4036 }
4037 \f
4038 /* The following functions are subroutines to fold_range_test and allow it to
4039 try to change a logical combination of comparisons into a range test.
4041 For example, both
4042 X == 2 || X == 3 || X == 4 || X == 5
4043 and
4044 X >= 2 && X <= 5
4045 are converted to
4046 (unsigned) (X - 2) <= 3
4048 We describe each set of comparisons as being either inside or outside
4049 a range, using a variable named like IN_P, and then describe the
4050 range with a lower and upper bound. If one of the bounds is omitted,
4051 it represents either the highest or lowest value of the type.
4053 In the comments below, we represent a range by two numbers in brackets
4054 preceded by a "+" to designate being inside that range, or a "-" to
4055 designate being outside that range, so the condition can be inverted by
4056 flipping the prefix. An omitted bound is represented by a "-". For
4057 example, "- [-, 10]" means being outside the range starting at the lowest
4058 possible value and ending at 10, in other words, being greater than 10.
4059 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4060 always false.
4062 We set up things so that the missing bounds are handled in a consistent
4063 manner so neither a missing bound nor "true" and "false" need to be
4064 handled using a special case. */
4066 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4067 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4068 and UPPER1_P are nonzero if the respective argument is an upper bound
4069 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4070 must be specified for a comparison. ARG1 will be converted to ARG0's
4071 type if both are specified. */
4073 static tree
4076 {
4077 tree tem;
4081 /* If neither arg represents infinity, do the normal operation.
4082 Else, if not a comparison, return infinity. Else handle the special
4083 comparison rules. Note that most of the cases below won't occur, but
4084 are handled for consistency. */
4087 {
4092 }
4097 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4098 for neither. In real maths, we cannot assume open ended ranges are
4099 the same. But, this is computer arithmetic, where numbers are finite.
4100 We can therefore make the transformation of any unbounded range with
4101 the value Z, Z being greater than any representable number. This permits
4102 us to treat unbounded ranges as equal. */
4106 {
4127 }
4130 }
4131 \f
4132 /* Given EXP, a logical expression, set the range it is testing into
4133 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4134 actually being tested. *PLOW and *PHIGH will be made of the same
4135 type as the returned expression. If EXP is not a comparison, we
4136 will most likely not be returning a useful value and range. Set
4137 *STRICT_OVERFLOW_P to true if the return value is only valid
4138 because signed overflow is undefined; otherwise, do not change
4139 *STRICT_OVERFLOW_P. */
4141 static tree
4144 {
4151 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4152 and see if we can refine the range. Some of the cases below may not
4153 happen, but it doesn't seem worth worrying about this. We "continue"
4154 the outer loop when we've changed something; otherwise we "break"
4155 the switch, which will "break" the while. */
4161 {
4166 {
4178 }
4181 {
4188 /* We can only do something if the range is testing for zero
4189 and if the second operand is an integer constant. Note that
4190 saying something is "in" the range we make is done by
4191 complementing IN_P since it will set in the initial case of
4192 being not equal to zero; "out" is leaving it alone. */
4199 {
4220 }
4222 /* If this is an unsigned comparison, we also know that EXP is
4223 greater than or equal to zero. We base the range tests we make
4224 on that fact, so we record it here so we can parse existing
4225 range tests. We test arg0_type since often the return type
4226 of, e.g. EQ_EXPR, is boolean. */
4228 {
4232 NULL_TREE))
4237 /* If the high bound is missing, but we have a nonzero low
4238 bound, reverse the range so it goes from zero to the low bound
4239 minus 1. */
4241 {
4246 }
4247 }
4253 /* (-x) IN [a,b] -> x in [-b, -a] */
4265 /* ~ X -> -X - 1 */
4274 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4275 move a constant to the other side. */
4280 /* If EXP is signed, any overflow in the computation is undefined,
4281 so we don't worry about it so long as our computations on
4282 the bounds don't overflow. For unsigned, overflow is defined
4283 and this is exactly the right thing. */
4295 /* Check for an unsigned range which has wrapped around the maximum
4296 value thus making n_high < n_low, and normalize it. */
4298 {
4304 /* If the range is of the form +/- [ x+1, x ], we won't
4305 be able to normalize it. But then, it represents the
4306 whole range or the empty set, so make it
4307 +/- [ -, - ]. */
4311 else
4313 }
4314 else
4338 /* If we're converting arg0 from an unsigned type, to exp,
4339 a signed type, we will be doing the comparison as unsigned.
4340 The tests above have already verified that LOW and HIGH
4341 are both positive.
4343 So we have to ensure that we will handle large unsigned
4344 values the same way that the current signed bounds treat
4345 negative values. */
4348 {
4349 tree high_positive;
4350 tree equiv_type;
4351 /* For fixed-point modes, we need to pass the saturating flag
4352 as the 2nd parameter. */
4357 else
4361 /* A range without an upper bound is, naturally, unbounded.
4362 Since convert would have cropped a very large value, use
4363 the max value for the destination type. */
4364 high_positive
4371 high_positive),
4374 /* If the low bound is specified, "and" the range with the
4375 range for which the original unsigned value will be
4376 positive. */
4378 {
4382 integer_zero_node),
4383 high_positive))
4387 }
4388 else
4389 {
4390 /* Otherwise, "or" the range with the range of the input
4391 that will be interpreted as negative. */
4395 integer_zero_node),
4396 high_positive))
4400 }
4401 }
4409 }
4412 }
4414 /* If EXP is a constant, we can evaluate whether this is true or false. */
4416 {
4423 }
4427 }
4428 \f
4429 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4430 type, TYPE, return an expression to test if EXP is in (or out of, depending
4431 on IN_P) the range. Return 0 if the test couldn't be created. */
4433 static tree
4435 {
4437 tree value;
4439 #ifdef HAVE_canonicalize_funcptr_for_compare
4440 /* Disable this optimization for function pointer expressions
4441 on targets that require function pointer canonicalization. */
4446 #endif
4449 {
4455 }
4473 {
4475 {
4479 }
4481 }
4483 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4485 {
4487 HOST_WIDE_INT hi;
4492 {
4495 }
4496 else
4497 {
4500 }
4503 {
4505 {
4508 }
4511 }
4512 }
4514 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4515 This requires wrap-around arithmetics for the type of the expression. */
4517 {
4519 /* There is no requirement that LOW be within the range of ETYPE
4520 if the latter is a subtype. It must, however, be within the base
4521 type of ETYPE. So be sure we do the subtraction in that type. */
4534 }
4536 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4539 {
4542 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4543 for the type in question, as we rely on this here. */
4553 else
4555 }
4565 {
4567 {
4573 }
4575 }
4583 }
4584 \f
4585 /* Return the predecessor of VAL in its type, handling the infinite case. */
4587 static tree
4589 {
4595 else
4597 }
4599 /* Return the successor of VAL in its type, handling the infinite case. */
4601 static tree
4603 {
4609 else
4611 }
4613 /* Given two ranges, see if we can merge them into one. Return 1 if we
4614 can, 0 if we can't. Set the output range into the specified parameters. */
4616 static int
4619 {
4623 tree tem;
4633 /* Make range 0 be the range that starts first, or ends last if they
4634 start at the same value. Swap them if it isn't. */
4637 || (lowequal
4640 {
4644 }
4646 /* Now flag two cases, whether the ranges are disjoint or whether the
4647 second range is totally subsumed in the first. Note that the tests
4648 below are simplified by the ones above. */
4654 /* We now have four cases, depending on whether we are including or
4655 excluding the two ranges. */
4657 {
4658 /* If they don't overlap, the result is false. If the second range
4659 is a subset it is the result. Otherwise, the range is from the start
4660 of the second to the end of the first. */
4665 else
4667 }
4670 {
4671 /* If they don't overlap, the result is the first range. If they are
4672 equal, the result is false. If the second range is a subset of the
4673 first, and the ranges begin at the same place, we go from just after
4674 the end of the second range to the end of the first. If the second
4675 range is not a subset of the first, or if it is a subset and both
4676 ranges end at the same place, the range starts at the start of the
4677 first range and ends just before the second range.
4678 Otherwise, we can't describe this as a single range. */
4684 {
4689 {
4690 /* We are in the weird situation where high0 > high1 but
4691 high1 has no successor. Punt. */
4693 }
4694 }
4696 {
4701 {
4702 /* low0 < low1 but low1 has no predecessor. Punt. */
4704 }
4705 }
4706 else
4708 }
4711 {
4712 /* If they don't overlap, the result is the second range. If the second
4713 is a subset of the first, the result is false. Otherwise,
4714 the range starts just after the first range and ends at the
4715 end of the second. */
4720 else
4721 {
4726 {
4727 /* high1 > high0 but high0 has no successor. Punt. */
4729 }
4730 }
4731 }
4733 else
4734 {
4735 /* The case where we are excluding both ranges. Here the complex case
4736 is if they don't overlap. In that case, the only time we have a
4737 range is if they are adjacent. If the second is a subset of the
4738 first, the result is the first. Otherwise, the range to exclude
4739 starts at the beginning of the first range and ends at the end of the
4740 second. */
4742 {
4747 else
4748 {
4749 /* Canonicalize - [min, x] into - [-, x]. */
4752 {
4757 /* FALLTHROUGH */
4770 }
4772 /* Canonicalize - [x, max] into - [x, -]. */
4775 {
4780 /* FALLTHROUGH */
4795 }
4797 /* The ranges might be also adjacent between the maximum and
4798 minimum values of the given type. For
4799 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4800 return + [x + 1, y - 1]. */
4802 {
4809 }
4810 else
4812 }
4813 }
4816 else
4818 }
4822 }
4823 \f
4825 /* Subroutine of fold, looking inside expressions of the form
4826 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4827 of the COND_EXPR. This function is being used also to optimize
4828 A op B ? C : A, by reversing the comparison first.
4830 Return a folded expression whose code is not a COND_EXPR
4831 anymore, or NULL_TREE if no folding opportunity is found. */
4833 static tree
4835 {
4840 tree tem;
4845 /* If we have A op 0 ? A : -A, consider applying the following
4846 transformations:
4848 A == 0? A : -A same as -A
4849 A != 0? A : -A same as A
4850 A >= 0? A : -A same as abs (A)
4851 A > 0? A : -A same as abs (A)
4852 A <= 0? A : -A same as -abs (A)
4853 A < 0? A : -A same as -abs (A)
4855 None of these transformations work for modes with signed
4856 zeros. If A is +/-0, the first two transformations will
4857 change the sign of the result (from +0 to -0, or vice
4858 versa). The last four will fix the sign of the result,
4859 even though the original expressions could be positive or
4860 negative, depending on the sign of A.
4862 Note that all these transformations are correct if A is
4863 NaN, since the two alternatives (A and -A) are also NaNs. */
4870 /* In the case that A is of the form X-Y, '-A' (arg2) may
4871 have already been folded to Y-X, check for that. */
4879 {
4891 /* Fall through. */
4913 }
4915 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4916 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4917 both transformations are correct when A is NaN: A != 0
4918 is then true, and A == 0 is false. */
4922 {
4927 }
4929 /* Try some transformations of A op B ? A : B.
4931 A == B? A : B same as B
4932 A != B? A : B same as A
4933 A >= B? A : B same as max (A, B)
4934 A > B? A : B same as max (B, A)
4935 A <= B? A : B same as min (A, B)
4936 A < B? A : B same as min (B, A)
4938 As above, these transformations don't work in the presence
4939 of signed zeros. For example, if A and B are zeros of
4940 opposite sign, the first two transformations will change
4941 the sign of the result. In the last four, the original
4942 expressions give different results for (A=+0, B=-0) and
4943 (A=-0, B=+0), but the transformed expressions do not.
4945 The first two transformations are correct if either A or B
4946 is a NaN. In the first transformation, the condition will
4947 be false, and B will indeed be chosen. In the case of the
4948 second transformation, the condition A != B will be true,
4949 and A will be chosen.
4951 The conversions to max() and min() are not correct if B is
4952 a number and A is not. The conditions in the original
4953 expressions will be false, so all four give B. The min()
4954 and max() versions would give a NaN instead. */
4957 /* Avoid these transformations if the COND_EXPR may be used
4958 as an lvalue in the C++ front-end. PR c++/19199. */
4959 && (in_gimple_form
4964 {
4969 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4971 {
4975 }
4978 {
4987 /* In C++ a ?: expression can be an lvalue, so put the
4988 operand which will be used if they are equal first
4989 so that we can convert this back to the
4990 corresponding COND_EXPR. */
4992 {
4999 }
5006 {
5013 }
5026 }
5027 }
5029 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5030 we might still be able to simplify this. For example,
5031 if C1 is one less or one more than C2, this might have started
5032 out as a MIN or MAX and been transformed by this function.
5033 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5039 {
5041 /* We can replace A with C1 in this case. */
5046 /* If C1 is C2 + 1, this is min(A, C2). */
5048 OEP_ONLY_CONST)
5052 OEP_ONLY_CONST))
5054 type,
5056 arg2));
5060 /* If C1 is C2 - 1, this is min(A, C2). */
5062 OEP_ONLY_CONST)
5066 OEP_ONLY_CONST))
5068 type,
5070 arg2));
5074 /* If C1 is C2 - 1, this is max(A, C2). */
5076 OEP_ONLY_CONST)
5080 OEP_ONLY_CONST))
5082 type,
5084 arg2));
5088 /* If C1 is C2 + 1, this is max(A, C2). */
5090 OEP_ONLY_CONST)
5094 OEP_ONLY_CONST))
5096 type,
5098 arg2));
5104 }
5107 }
5110 \f
5111 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5112 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
5113 #endif
5115 /* EXP is some logical combination of boolean tests. See if we can
5116 merge it into some range test. Return the new tree if so. */
5118 static tree
5120 {
5128 tree tem;
5132 /* If this is an OR operation, invert both sides; we will invert
5133 again at the end. */
5137 /* If both expressions are the same, if we can merge the ranges, and we
5138 can build the range test, return it or it inverted. If one of the
5139 ranges is always true or always false, consider it to be the same
5140 expression as the other. */
5148 {
5152 }
5154 /* On machines where the branch cost is expensive, if this is a
5155 short-circuited branch and the underlying object on both sides
5156 is the same, make a non-short-circuit operation. */
5162 {
5163 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5164 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5165 which cases we can't do this. */
5173 {
5182 {
5185 WARN_STRICT_OVERFLOW_COMPARISON);
5189 }
5190 }
5191 }
5194 }
5195 \f
5196 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5197 bit value. Arrange things so the extra bits will be set to zero if and
5198 only if C is signed-extended to its full width. If MASK is nonzero,
5199 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5201 static tree
5203 {
5206 tree temp;
5211 /* We work by getting just the sign bit into the low-order bit, then
5212 into the high-order bit, then sign-extend. We then XOR that value
5213 with C. */
5217 /* We must use a signed type in order to get an arithmetic right shift.
5218 However, we must also avoid introducing accidental overflows, so that
5219 a subsequent call to integer_zerop will work. Hence we must
5220 do the type conversion here. At this point, the constant is either
5221 zero or one, and the conversion to a signed type can never overflow.
5222 We could get an overflow if this conversion is done anywhere else. */
5231 /* If necessary, convert the type back to match the type of C. */
5236 }
5237 \f
5238 /* Find ways of folding logical expressions of LHS and RHS:
5239 Try to merge two comparisons to the same innermost item.
5240 Look for range tests like "ch >= '0' && ch <= '9'".
5241 Look for combinations of simple terms on machines with expensive branches
5242 and evaluate the RHS unconditionally.
5244 For example, if we have p->a == 2 && p->b == 4 and we can make an
5245 object large enough to span both A and B, we can do this with a comparison
5246 against the object ANDed with the a mask.
5248 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5249 operations to do this with one comparison.
5251 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5252 function and the one above.
5254 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5255 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5257 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5258 two operands.
5260 We return the simplified tree or 0 if no optimization is possible. */
5262 static tree
5264 {
5265 /* If this is the "or" of two comparisons, we can do something if
5266 the comparisons are NE_EXPR. If this is the "and", we can do something
5267 if the comparisons are EQ_EXPR. I.e.,
5268 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5270 WANTED_CODE is this operation code. For single bit fields, we can
5271 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5272 comparison for one-bit fields. */
5294 /* Start by getting the comparison codes. Fail if anything is volatile.
5295 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5296 it were surrounded with a NE_EXPR. */
5305 {
5309 }
5312 {
5316 }
5327 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5330 {
5331 tree result;
5334 {
5339 }
5342 {
5348 }
5349 }
5354 /* If the RHS can be evaluated unconditionally and its operands are
5355 simple, it wins to evaluate the RHS unconditionally on machines
5356 with expensive branches. In this case, this isn't a comparison
5357 that can be merged. Avoid doing this if the RHS is a floating-point
5358 comparison since those can trap. */
5364 {
5365 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5376 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5388 {
5392 }
5393 }
5395 /* See if the comparisons can be merged. Then get all the parameters for
5396 each side. */
5420 /* It must be true that the inner operation on the lhs of each
5421 comparison must be the same if we are to be able to do anything.
5422 Then see if we have constants. If not, the same must be true for
5423 the rhs's. */
5434 else
5437 /* If either comparison code is not correct for our logical operation,
5438 fail. However, we can convert a one-bit comparison against zero into
5439 the opposite comparison against that bit being set in the field. */
5443 {
5445 {
5446 /* Make the left operand unsigned, since we are only interested
5447 in the value of one bit. Otherwise we are doing the wrong
5448 thing below. */
5451 }
5452 else
5454 }
5456 /* This is analogous to the code for l_const above. */
5458 {
5460 {
5463 }
5464 else
5466 }
5468 /* See if we can find a mode that contains both fields being compared on
5469 the left. If we can't, fail. Otherwise, update all constants and masks
5470 to be relative to a field of that size. */
5475 volatilep);
5485 {
5488 }
5496 {
5504 {
5508 }
5509 }
5511 {
5519 {
5523 }
5524 }
5526 /* Handle the case of comparisons with constants. If there is something in
5527 common between the masks, those bits of the constants must be the same.
5528 If not, the condition is always false. Test for this to avoid generating
5529 incorrect code below. */
5534 {
5536 {
5539 }
5540 else
5541 {
5544 }
5545 }
5548 }
5549 \f
5550 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5551 constant. */
5553 static tree
5555 {
5558 tree comp_const;
5559 tree minmax_const;
5561 tree inner;
5572 /* If something does not permit us to optimize, return the original tree. */
5580 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5581 and GT_EXPR, doing the rest with recursive calls using logical
5582 simplifications. */
5584 {
5586 {
5592 }
5595 return
5597 optimize_minmax_comparison
5599 optimize_minmax_comparison
5604 /* MAX (X, 0) == 0 -> X <= 0 */
5608 /* MAX (X, 0) == 5 -> X == 5 */
5612 /* MAX (X, 0) == -1 -> false */
5616 /* MIN (X, 0) == 0 -> X >= 0 */
5620 /* MIN (X, 0) == 5 -> false */
5623 else
5624 /* MIN (X, 0) == -1 -> X == -1 */
5629 /* MAX (X, 0) > 0 -> X > 0
5630 MAX (X, 0) > 5 -> X > 5 */
5634 /* MAX (X, 0) > -1 -> true */
5638 /* MIN (X, 0) > 0 -> false
5639 MIN (X, 0) > 5 -> false */
5642 else
5643 /* MIN (X, 0) > -1 -> X > -1 */
5648 }
5649 }
5650 \f
5651 /* T is an integer expression that is being multiplied, divided, or taken a
5652 modulus (CODE says which and what kind of divide or modulus) by a
5653 constant C. See if we can eliminate that operation by folding it with
5654 other operations already in T. WIDE_TYPE, if non-null, is a type that
5655 should be used for the computation if wider than our type.
5657 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5658 (X * 2) + (Y * 4). We must, however, be assured that either the original
5659 expression would not overflow or that overflow is undefined for the type
5660 in the language in question.
5662 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5663 the machine has a multiply-accumulate insn or that this is part of an
5664 addressing calculation.
5666 If we return a non-null expression, it is an equivalent form of the
5667 original computation, but need not be in the original type.
5669 We set *STRICT_OVERFLOW_P to true if the return values depends on
5670 signed overflow being undefined. Otherwise we do not change
5671 *STRICT_OVERFLOW_P. */
5673 static tree
5676 {
5677 /* To avoid exponential search depth, refuse to allow recursion past
5678 three levels. Beyond that (1) it's highly unlikely that we'll find
5679 something interesting and (2) we've probably processed it before
5680 when we built the inner expression. */
5683 tree ret;
5688 depth++;
5690 depth--;
5693 }
5695 static tree
5698 {
5709 /* Don't deal with constants of zero here; they confuse the code below. */
5719 /* Note that we need not handle conditional operations here since fold
5720 already handles those cases. So just do arithmetic here. */
5722 {
5724 /* For a constant, we can always simplify if we are a multiply
5725 or (for divide and modulus) if it is a multiple of our constant. */
5733 /* If op0 is an expression ... */
5739 /* ... and has wrapping overflow, and its type is smaller
5740 than ctype, then we cannot pass through as widening. */
5746 /* ... or this is a truncation (t is narrower than op0),
5747 then we cannot pass through this narrowing. */
5750 /* ... or signedness changes for division or modulus,
5751 then we cannot pass through this conversion. */
5755 /* ... or has undefined overflow while the converted to
5756 type has not, we cannot do the operation in the inner type
5757 as that would introduce undefined overflow. */
5762 /* Pass the constant down and see if we can make a simplification. If
5763 we can, replace this expression with the inner simplification for
5764 possible later conversion to our or some other type. */
5769 code == MULT_EXPR
5771 strict_overflow_p))))
5776 /* If widening the type changes it from signed to unsigned, then we
5777 must avoid building ABS_EXPR itself as unsigned. */
5779 {
5783 {
5786 }
5788 }
5789 /* If the constant is negative, we cannot simplify this. */
5792 /* FALLTHROUGH */
5800 /* If widening the type changes the signedness, then we can't perform
5801 this optimization as that changes the result. */
5805 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5811 {
5818 }
5822 /* If the second operand is constant, this is a multiplication
5823 or floor division, by a power of two, so we can treat it that
5824 way unless the multiplier or divisor overflows. Signed
5825 left-shift overflow is implementation-defined rather than
5826 undefined in C90, so do not convert signed left shift into
5827 multiplication. */
5830 /* const_binop may not detect overflow correctly,
5831 so check for it explicitly here. */
5836 size_one_node,
5846 /* See if we can eliminate the operation on both sides. If we can, we
5847 can return a new PLUS or MINUS. If we can't, the only remaining
5848 cases where we can do anything are if the second operand is a
5849 constant. */
5855 /* If not multiplication, we can only do this if both operands
5856 are divisible by c. */
5859 {
5864 }
5866 /* If this was a subtraction, negate OP1 and set it to be an addition.
5867 This simplifies the logic below. */
5874 /* If either OP1 or C are negative, this optimization is not safe for
5875 some of the division and remainder types while for others we need
5876 to change the code. */
5878 {
5886 }
5888 /* If it's a multiply or a division/modulus operation of a multiple
5889 of our constant, do the operation and verify it doesn't overflow. */
5892 {
5895 /* We allow the constant to overflow with wrapping semantics. */
5899 }
5900 else
5903 /* If we have an unsigned type is not a sizetype, we cannot widen
5904 the operation since it will change the result if the original
5905 computation overflowed. */
5911 /* If we were able to eliminate our operation from the first side,
5912 apply our operation to the second side and reform the PLUS. */
5916 /* The last case is if we are a multiply. In that case, we can
5917 apply the distributive law to commute the multiply and addition
5918 if the multiplication of the constants doesn't overflow. */
5924 op1);
5929 /* We have a special case here if we are doing something like
5930 (C * 8) % 4 since we know that's zero. */
5933 /* If the multiplication can overflow we cannot optimize this.
5934 ??? Until we can properly mark individual operations as
5935 not overflowing we need to treat sizetype special here as
5936 stor-layout relies on this opimization to make
5937 DECL_FIELD_BIT_OFFSET always a constant. */
5943 {
5946 }
5948 /* ... fall through ... */
5952 /* If we can extract our operation from the LHS, do so and return a
5953 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5954 do something only if the second operand is a constant. */
5968 /* If these are the same operation types, we can associate them
5969 assuming no overflow. */
5981 /* If these operations "cancel" each other, we have the main
5982 optimizations of this pass, which occur when either constant is a
5983 multiple of the other, in which case we replace this with either an
5984 operation or CODE or TCODE.
5986 If we have an unsigned type that is not a sizetype, we cannot do
5987 this since it will change the result if the original computation
5988 overflowed. */
5996 {
5998 {
6005 }
6007 {
6014 }
6015 }
6020 }
6023 }
6024 \f
6025 /* Return a node which has the indicated constant VALUE (either 0 or
6026 1), and is of the indicated TYPE. */
6028 tree
6030 {
6035 else
6037 }
6040 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6041 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6042 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6043 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6044 COND is the first argument to CODE; otherwise (as in the example
6045 given here), it is the second argument. TYPE is the type of the
6046 original expression. Return NULL_TREE if no simplification is
6047 possible. */
6049 static tree
6053 {
6060 /* This transformation is only worthwhile if we don't have to wrap
6061 arg in a SAVE_EXPR, and the operation can be simplified on at least
6062 one of the branches once its pushed inside the COND_EXPR. */
6067 {
6071 /* If this operand throws an expression, then it does not make
6072 sense to try to perform a logical or arithmetic operation
6073 involving it. */
6078 }
6079 else
6080 {
6085 }
6089 {
6093 else
6095 }
6097 {
6101 else
6103 }
6107 }
6109 \f
6110 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6112 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6113 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6114 ADDEND is the same as X.
6116 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6117 and finite. The problematic cases are when X is zero, and its mode
6118 has signed zeros. In the case of rounding towards -infinity,
6119 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6120 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6122 bool
6124 {
6128 /* Don't allow the fold with -fsignaling-nans. */
6132 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6136 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6141 /* The mode has signed zeros, and we have to honor their sign.
6142 In this situation, there is only one case we can return true for.
6143 X - 0 is the same as X unless rounding towards -infinity is
6144 supported. */
6146 }
6148 /* Subroutine of fold() that checks comparisons of built-in math
6149 functions against real constants.
6151 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6152 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6153 is the type of the result and ARG0 and ARG1 are the operands of the
6154 comparison. ARG1 must be a TREE_REAL_CST.
6156 The function returns the constant folded tree if a simplification
6157 can be made, and NULL_TREE otherwise. */
6159 static tree
6162 {
6163 REAL_VALUE_TYPE c;
6166 {
6172 {
6173 /* sqrt(x) < y is always false, if y is negative. */
6177 /* sqrt(x) > y is always true, if y is negative and we
6178 don't care about NaNs, i.e. negative values of x. */
6182 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6185 }
6187 {
6188 REAL_VALUE_TYPE c2;
6194 {
6195 /* sqrt(x) > y is x == +Inf, when y is very large. */
6200 /* sqrt(x) > y is always false, when y is very large
6201 and we don't care about infinities. */
6203 }
6205 /* sqrt(x) > c is the same as x > c*c. */
6208 }
6210 {
6211 REAL_VALUE_TYPE c2;
6217 {
6218 /* sqrt(x) < y is always true, when y is a very large
6219 value and we don't care about NaNs or Infinities. */
6223 /* sqrt(x) < y is x != +Inf when y is very large and we
6224 don't care about NaNs. */
6229 /* sqrt(x) < y is x >= 0 when y is very large and we
6230 don't care about Infinities. */
6235 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6244 dconst0)),
6247 c2)));
6248 }
6250 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6255 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6258 {
6263 dconst0)),
6266 c2)));
6267 }
6268 }
6269 }
6272 }
6274 /* Subroutine of fold() that optimizes comparisons against Infinities,
6275 either +Inf or -Inf.
6277 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6278 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6279 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6281 The function returns the constant folded tree if a simplification
6282 can be made, and NULL_TREE otherwise. */
6284 static tree
6286 {
6288 REAL_VALUE_TYPE max;
6289 tree temp;
6294 /* For negative infinity swap the sense of the comparison. */
6300 {
6302 /* x > +Inf is always false, if with ignore sNANs. */
6308 /* x <= +Inf is always true, if we don't case about NaNs. */
6312 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6315 {
6318 }
6323 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6329 /* x < +Inf is always equal to x <= DBL_MAX. */
6335 /* x != +Inf is always equal to !(x > DBL_MAX). */
6347 }
6350 }
6352 /* Subroutine of fold() that optimizes comparisons of a division by
6353 a nonzero integer constant against an integer constant, i.e.
6354 X/C1 op C2.
6356 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6357 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6358 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6360 The function returns the constant folded tree if a simplification
6361 can be made, and NULL_TREE otherwise. */
6363 static tree
6365 {
6370 HOST_WIDE_INT hpart;
6375 /* We have to do this the hard way to detect unsigned overflow.
6376 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6387 {
6392 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6400 }
6402 {
6406 {
6425 }
6426 }
6427 else
6428 {
6429 /* A negative divisor reverses the relational operators. */
6435 {
6454 }
6455 }
6458 {
6479 {
6482 }
6487 {
6490 }
6495 {
6498 }
6503 {
6506 }
6511 }
6514 }
6517 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6518 equality/inequality test, then return a simplified form of the test
6519 using a sign testing. Otherwise return NULL. TYPE is the desired
6520 result type. */
6522 static tree
6524 tree result_type)
6525 {
6526 /* If this is testing a single bit, we can optimize the test. */
6530 {
6531 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6532 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6536 /* This is only a win if casting to a signed type is cheap,
6537 i.e. when arg00's type is not a partial mode. */
6540 {
6545 }
6546 }
6549 }
6551 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6552 equality/inequality test, then return a simplified form of
6553 the test using shifts and logical operations. Otherwise return
6554 NULL. TYPE is the desired result type. */
6556 tree
6558 tree result_type)
6559 {
6560 /* If this is testing a single bit, we can optimize the test. */
6564 {
6573 /* First, see if we can fold the single bit test into a sign-bit
6574 test. */
6576 result_type);
6580 /* Otherwise we have (A & C) != 0 where C is a single bit,
6581 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6582 Similarly for (A & C) == 0. */
6584 /* If INNER is a right shift of a constant and it plus BITNUM does
6585 not overflow, adjust BITNUM and INNER. */
6592 {
6595 }
6597 /* If we are going to be able to omit the AND below, we must do our
6598 operations as unsigned. If we must use the AND, we have a choice.
6599 Normally unsigned is faster, but for some machines signed is. */
6600 #ifdef LOAD_EXTEND_OP
6603 #else
6605 #endif
6621 /* Put the AND last so it can combine with more things. */
6624 /* Make sure to return the proper type. */
6628 }
6630 }
6632 /* Check whether we are allowed to reorder operands arg0 and arg1,
6633 such that the evaluation of arg1 occurs before arg0. */
6635 static bool
6637 {
6644 }
6646 /* Test whether it is preferable two swap two operands, ARG0 and
6647 ARG1, for example because ARG0 is an integer constant and ARG1
6648 isn't. If REORDER is true, only recommend swapping if we can
6649 evaluate the operands in reverse order. */
6651 bool
6653 {
6689 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6690 for commutative and comparison operators. Ensuring a canonical
6691 form allows the optimizers to find additional redundancies without
6692 having to explicitly check for both orderings. */
6698 /* Put SSA_NAMEs last. */
6704 /* Put variables last. */
6711 }
6713 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6714 ARG0 is extended to a wider type. */
6716 static tree
6718 {
6720 tree arg1_unw;
6729 #ifdef HAVE_canonicalize_funcptr_for_compare
6730 /* Disable this optimization if we're casting a function pointer
6731 type on targets that require function pointer canonicalization. */
6736 #endif
6743 /* If possible, express the comparison in the shorter mode. */
6763 /* If we are comparing with the integer that does not fit into the range
6764 of the shorter type, the result is known. */
6775 {
6802 }
6805 }
6807 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6808 ARG0 just the signedness is changed. */
6810 static tree
6813 {
6814 tree arg0_inner;
6824 #ifdef HAVE_canonicalize_funcptr_for_compare
6825 /* Disable this optimization if we're casting a function pointer
6826 type on targets that require function pointer canonicalization. */
6831 #endif
6836 /* If the conversion is from an integral subtype to its basetype
6837 leave it alone. */
6856 else
6860 }
6862 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
6863 step of the array. Reconstructs s and delta in the case of s * delta
6864 being an integer constant (and thus already folded).
6865 ADDR is the address. MULT is the multiplicative expression.
6866 If the function succeeds, the new address expression is returned. Otherwise
6867 NULL_TREE is returned. */
6869 static tree
6871 {
6875 tree itype;
6878 /* Strip the nops that might be added when converting op1 to sizetype. */
6881 /* Canonicalize op1 into a possibly non-constant delta
6882 and an INTEGER_CST s. */
6884 {
6891 {
6894 }
6896 {
6899 }
6900 else
6902 }
6904 {
6907 }
6908 else
6909 {
6910 /* Simulate we are delta * 1. */
6913 }
6916 {
6918 {
6919 /* Remember if this was a multi-dimensional array. */
6932 {
6935 }
6936 else
6937 {
6938 /* Try if delta is a multiple of step. */
6943 }
6945 /* Only fold here if we can verify we do not overflow one
6946 dimension of a multi-dimensional array. */
6948 {
6949 tree tmp;
6965 }
6968 }
6969 else
6974 }
6976 /* We found the suitable array reference. So copy everything up to it,
6977 and replace the index. */
6984 {
6988 }
6996 }
6999 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7000 means A >= Y && A != MAX, but in this case we know that
7001 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7003 static tree
7005 {
7012 else
7021 {
7024 }
7026 {
7029 }
7030 else
7037 {
7038 /* Convert the pointer types into integer before taking the difference. */
7042 }
7043 else
7050 }
7052 /* Fold a sum or difference of at least one multiplication.
7053 Returns the folded tree or NULL if no simplification could be made. */
7055 static tree
7057 {
7061 /* (A * C) +- (B * C) -> (A+-B) * C.
7062 (A * C) +- A -> A * (C+-1).
7063 We are most concerned about the case where C is a constant,
7064 but other combinations show up during loop reduction. Since
7065 it is not difficult, try all four possibilities. */
7068 {
7071 }
7073 {
7076 }
7077 else
7078 {
7079 /* We cannot generate constant 1 for fract. */
7084 }
7086 {
7089 }
7091 {
7094 }
7095 else
7096 {
7097 /* We cannot generate constant 1 for fract. */
7102 }
7114 /* No identical multiplicands; see if we can find a common
7115 power-of-two factor in non-power-of-two multiplies. This
7116 can help in multi-dimensional array access. */
7119 {
7122 tree maybe_same;
7126 /* Move min of absolute values to int11. */
7129 {
7134 }
7135 else
7139 {
7147 }
7148 }
7158 }
7160 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7161 specified by EXPR into the buffer PTR of length LEN bytes.
7162 Return the number of bytes placed in the buffer, or zero
7163 upon failure. */
7165 static int
7167 {
7178 {
7182 else
7187 {
7194 else
7196 }
7197 else
7200 }
7202 }
7205 /* Subroutine of native_encode_expr. Encode the REAL_CST
7206 specified by EXPR into the buffer PTR of length LEN bytes.
7207 Return the number of bytes placed in the buffer, or zero
7208 upon failure. */
7210 static int
7212 {
7218 /* There are always 32 bits in each long, no matter the size of
7219 the hosts long. We handle floating point representations with
7220 up to 192 bits. */
7231 {
7236 {
7243 else
7245 }
7246 else
7249 }
7251 }
7253 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7254 specified by EXPR into the buffer PTR of length LEN bytes.
7255 Return the number of bytes placed in the buffer, or zero
7256 upon failure. */
7258 static int
7260 {
7262 tree part;
7273 }
7276 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7277 specified by EXPR into the buffer PTR of length LEN bytes.
7278 Return the number of bytes placed in the buffer, or zero
7279 upon failure. */
7281 static int
7283 {
7293 {
7295 {
7298 }
7299 else
7303 {
7306 }
7307 else
7308 {
7312 }
7314 }
7316 }
7319 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7320 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7321 buffer PTR of length LEN bytes. Return the number of bytes
7322 placed in the buffer, or zero upon failure. */
7324 int
7326 {
7328 {
7343 }
7344 }
7347 /* Subroutine of native_interpret_expr. Interpret the contents of
7348 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7349 If the buffer cannot be interpreted, return NULL_TREE. */
7351 static tree
7353 {
7367 {
7370 {
7377 else
7379 }
7380 else
7386 else
7389 }
7392 }
7395 /* Subroutine of native_interpret_expr. Interpret the contents of
7396 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7397 If the buffer cannot be interpreted, return NULL_TREE. */
7399 static tree
7401 {
7406 /* There are always 32 bits in each long, no matter the size of
7407 the hosts long. We handle floating point representations with
7408 up to 192 bits. */
7409 REAL_VALUE_TYPE r;
7420 {
7423 {
7430 else
7432 }
7433 else
7438 }
7442 }
7445 /* Subroutine of native_interpret_expr. Interpret the contents of
7446 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7447 If the buffer cannot be interpreted, return NULL_TREE. */
7449 static tree
7451 {
7466 }
7469 /* Subroutine of native_interpret_expr. Interpret the contents of
7470 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7471 If the buffer cannot be interpreted, return NULL_TREE. */
7473 static tree
7475 {
7487 {
7492 }
7494 }
7497 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7498 the buffer PTR of length LEN as a constant of type TYPE. For
7499 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7500 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7501 return NULL_TREE. */
7503 tree
7505 {
7507 {
7524 }
7525 }
7528 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7529 TYPE at compile-time. If we're unable to perform the conversion
7530 return NULL_TREE. */
7532 static tree
7534 {
7535 /* We support up to 512-bit values (for V8DFmode). */
7539 /* Check that the host and target are sane. */
7548 }
7550 /* Build an expression for the address of T. Folds away INDIRECT_REF
7551 to avoid confusing the gimplify process. When IN_FOLD is true
7552 avoid modifications of T. */
7554 static tree
7556 {
7557 /* The size of the object is not relevant when talking about its address. */
7561 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7564 {
7569 }
7571 {
7581 }
7582 else
7586 }
7588 /* Build an expression for the address of T with type PTRTYPE. This
7589 function modifies the input parameter 'T' by sometimes setting the
7590 TREE_ADDRESSABLE flag. */
7592 tree
7594 {
7596 }
7598 /* Build an expression for the address of T. This function modifies
7599 the input parameter 'T' by sometimes setting the TREE_ADDRESSABLE
7600 flag. When called from fold functions, use fold_addr_expr instead. */
7602 tree
7604 {
7608 }
7610 /* Same as build_fold_addr_expr, builds an expression for the address
7611 of T, but avoids touching the input node 't'. Fold functions
7612 should use this version. */
7614 static tree
7616 {
7620 }
7622 /* Fold a unary expression of code CODE and type TYPE with operand
7623 OP0. Return the folded expression if folding is successful.
7624 Otherwise, return NULL_TREE. */
7626 tree
7628 {
7629 tree tem;
7630 tree arg0;
7638 {
7641 {
7642 /* Don't use STRIP_NOPS, because signedness of argument type
7643 matters. */
7645 }
7646 else
7647 {
7648 /* Strip any conversions that don't change the mode. This
7649 is safe for every expression, except for a comparison
7650 expression because its signedness is derived from its
7651 operands.
7653 Note that this is done as an internal manipulation within
7654 the constant folder, in order to find the simplest
7655 representation of the arguments so that their form can be
7656 studied. In any cases, the appropriate type conversions
7657 should be put back in the tree that will get out of the
7658 constant folder. */
7660 }
7661 }
7664 {
7669 {
7679 /* If this was a conversion, and all we did was to move into
7680 inside the COND_EXPR, bring it back out. But leave it if
7681 it is a conversion from integer to integer and the
7682 result precision is no wider than a word since such a
7683 conversion is cheap and may be optimized away by combine,
7684 while it couldn't if it were outside the COND_EXPR. Then return
7685 so we don't get into an infinite recursion loop taking the
7686 conversion out and then back in. */
7698 && (INTEGRAL_TYPE_P
7710 }
7712 {
7714 {
7718 }
7722 integer_one_node),
7724 integer_zero_node));
7725 }
7726 }
7729 {
7731 /* Re-association barriers around constants and other re-association
7732 barriers can be removed. */
7738 CASE_CONVERT:
7744 /* If we have (type) (a CMP b) and type is an integral type, return
7745 new expression involving the new type. */
7750 /* Handle cases of two conversions in a row. */
7752 {
7774 /* In addition to the cases of two conversions in a row
7775 handled below, if we are converting something to its own
7776 type via an object of identical or wider precision, neither
7777 conversion is needed. */
7784 /* Likewise, if the intermediate and final types are either both
7785 float or both integer, we don't need the middle conversion if
7786 it is wider than the final type and doesn't change the signedness
7787 (for integers). Avoid this if the final type is a pointer
7788 since then we sometimes need the inner conversion. Likewise if
7789 the outer has a precision not equal to the size of its mode. */
7798 && ! final_ptr
7802 /* If we have a sign-extension of a zero-extended value, we can
7803 replace that by a single zero-extension. */
7809 /* Two conversions in a row are not needed unless:
7810 - some conversion is floating-point (overstrict for now), or
7811 - some conversion is a vector (overstrict for now), or
7812 - the intermediate type is narrower than both initial and
7813 final, or
7814 - the intermediate type and innermost type differ in signedness,
7815 and the outermost type is wider than the intermediate, or
7816 - the initial type is a pointer type and the precisions of the
7817 intermediate and final types differ, or
7818 - the final type is a pointer type and the precisions of the
7819 initial and intermediate types differ. */
7833 }
7835 /* Handle (T *)&A.B.C for A being of type T and B and C
7836 living at offset zero. This occurs frequently in
7837 C++ upcasting and then accessing the base. */
7841 {
7843 tree offset;
7849 /* If the reference was to a (constant) zero offset, we can use
7850 the address of the base if it has the same base type
7851 as the result type. */
7856 }
7860 /* Detect assigning a bitfield. */
7862 && DECL_BIT_FIELD
7864 {
7865 /* Don't leave an assignment inside a conversion
7866 unless assigning a bitfield. */
7868 /* First do the assignment, then return converted constant. */
7873 }
7875 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7876 constants (if x has signed type, the sign bit cannot be set
7877 in c). This folds extension into the BIT_AND_EXPR.
7878 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7879 very likely don't have maximal range for their precision and this
7880 transformation effectively doesn't preserve non-maximal ranges. */
7884 {
7894 <= HOST_BITS_PER_WIDE_INT
7896 {
7903 #ifdef LOAD_EXTEND_OP
7905 && !flag_syntax_only
7908 {
7912 }
7913 #endif
7914 }
7916 {
7922 }
7923 }
7925 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7926 when one of the new casts will fold away. Conservatively we assume
7927 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7933 {
7939 }
7941 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7942 of the same precision, and X is an integer type not narrower than
7943 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7949 {
7954 }
7956 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7957 type of X and Y (integer types only). */
7962 {
7963 /* Be careful not to introduce new overflows. */
7964 tree mult_type;
7967 else
7974 }
7989 /* For integral conversions with the same precision or pointer
7990 conversions use a NOP_EXPR instead. */
7996 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
7997 a sub-type to its base type as generated by the Ada FE. */
8002 /* Strip inner integral conversions that do not change the precision. */
8025 /* Convert fabs((double)float) into (double)fabsf(float). */
8028 {
8033 targ0));
8034 }
8035 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8041 /* Strip sign ops from argument. */
8043 {
8047 }
8054 {
8059 }
8061 {
8066 }
8076 /* Convert ~ (-A) to A - 1. */
8081 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8089 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8102 /* Perform BIT_NOT_EXPR on each element individually. */
8104 {
8109 {
8111 {
8117 }
8118 else
8121 }
8124 }
8129 /* The argument to invert_truthvalue must have Boolean type. */
8133 /* Note that the operand of this must be an int
8134 and its values must be 0 or 1.
8135 ("true" is a fixed value perhaps depending on the language,
8136 but we don't handle values other than 1 correctly yet.) */
8151 {
8159 }
8161 {
8165 }
8167 {
8171 {
8180 }
8181 }
8193 {
8201 }
8203 {
8207 }
8209 {
8213 {
8222 }
8223 }
8229 }
8231 /* Fold a binary expression of code CODE and type TYPE with operands
8232 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8233 Return the folded expression if folding is successful. Otherwise,
8234 return NULL_TREE. */
8236 static tree
8238 {
8245 else
8248 /* MIN (MAX (a, b), b) == b. */
8253 /* MIN (MAX (b, a), b) == b. */
8259 /* MIN (a, MAX (a, b)) == a. */
8265 /* MIN (a, MAX (b, a)) == a. */
8272 }
8274 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8275 by changing CODE to reduce the magnitude of constants involved in
8276 ARG0 of the comparison.
8277 Returns a canonicalized comparison tree if a simplification was
8278 possible, otherwise returns NULL_TREE.
8279 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8280 valid if signed overflow is undefined. */
8282 static tree
8286 {
8292 /* Match A +- CST code arg1 and CST code arg1. */
8299 /* Identify the constant in arg0 and its sign. */
8302 else
8306 /* Overflowed constants and zero will cause problems. */
8311 /* See if we can reduce the magnitude of the constant in
8312 arg0 by changing the comparison code. */
8314 {
8315 /* CST <= arg1 -> CST-1 < arg1. */
8318 /* -CST < arg1 -> -CST-1 <= arg1. */
8321 /* CST > arg1 -> CST-1 >= arg1. */
8324 /* -CST >= arg1 -> -CST-1 > arg1. */
8327 else
8329 /* arg1 code' CST' might be more canonical. */
8331 }
8332 else
8333 {
8334 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8338 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8342 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8346 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8350 else
8353 }
8355 /* Now build the constant reduced in magnitude. */
8361 /* If swapping might yield to a more canonical form, do so. */
8364 else
8366 }
8368 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8369 overflow further. Try to decrease the magnitude of constants involved
8370 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8371 and put sole constants at the second argument position.
8372 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8374 static tree
8377 {
8378 tree t;
8383 /* In principle pointers also have undefined overflow behavior,
8384 but that causes problems elsewhere. */
8389 /* Try canonicalization by simplifying arg0. */
8394 {
8398 }
8400 /* Try canonicalization by simplifying arg1 using the swapped
8401 comparison. */
8409 }
8411 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8412 space. This is used to avoid issuing overflow warnings for
8413 expressions like &p->x which can not wrap. */
8415 static bool
8417 {
8428 {
8431 }
8434 else
8435 {
8438 }
8453 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8454 array. */
8456 {
8457 HOST_WIDE_INT base_size;
8462 }
8465 }
8467 /* Subroutine of fold_binary. This routine performs all of the
8468 transformations that are common to the equality/inequality
8469 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8470 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8471 fold_binary should call fold_binary. Fold a comparison with
8472 tree code CODE and type TYPE with operands OP0 and OP1. Return
8473 the folded comparison or NULL_TREE. */
8475 static tree
8477 {
8490 /* If one arg is a real or integer constant, put it last. */
8494 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8501 {
8505 tree lhs;
8512 /* If the constant operation overflowed this can be
8513 simplified as a comparison against INT_MAX/INT_MIN. */
8516 {
8520 /* Get the sign of the constant on the lhs if the
8521 operation were VARIABLE + CONST1. */
8525 /* The sign of the constant determines if we overflowed
8526 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8527 Canonicalize to the INT_MIN overflow by swapping the comparison
8528 if necessary. */
8532 /* We now can look at the canonicalized case
8533 VARIABLE + 1 CODE2 INT_MIN
8534 and decide on the result. */
8543 }
8548 {
8550 "when changing X +- C1 cmp C2 to "
8552 WARN_STRICT_OVERFLOW_COMPARISON);
8554 }
8555 }
8557 /* For comparisons of pointers we can decompose it to a compile time
8558 comparison of the base objects and the offsets into the object.
8559 This requires at least one operand being an ADDR_EXPR or a
8560 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8566 {
8573 /* Get base and offset for the access. Strip ADDR_EXPR for
8574 get_inner_reference, but put it back by stripping INDIRECT_REF
8575 off the base object if possible. indirect_baseN will be true
8576 if baseN is not an address but refers to the object itself. */
8579 {
8585 else
8587 }
8589 {
8592 }
8596 {
8602 else
8604 }
8606 {
8609 }
8611 /* If we have equivalent bases we might be able to simplify. */
8614 {
8615 /* We can fold this expression to a constant if the non-constant
8616 offset parts are equal. */
8624 {
8631 "occur when comparing P +- C1 with "
8633 WARN_STRICT_OVERFLOW_CONDITIONAL);
8636 {
8650 }
8651 }
8652 /* We can simplify the comparison to a comparison of the variable
8653 offset parts if the constant offset parts are equal.
8654 Be careful to use signed size type here because otherwise we
8655 mess with array offsets in the wrong way. This is possible
8656 because pointer arithmetic is restricted to retain within an
8657 object and overflow on pointer differences is undefined as of
8658 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8662 {
8663 tree signed_size_type_node;
8666 /* By converting to signed size type we cover middle-end pointer
8667 arithmetic which operates on unsigned pointer types of size
8668 type size and ARRAY_REF offsets which are properly sign or
8669 zero extended from their type in case it is narrower than
8670 size type. */
8673 else
8677 else
8685 "occur when comparing P +- C1 with "
8687 WARN_STRICT_OVERFLOW_COMPARISON);
8690 }
8691 }
8692 /* For non-equal bases we can simplify if they are addresses
8693 of local binding decls or constants. */
8695 /* We know that !operand_equal_p (base0, base1, 0)
8696 because the if condition was false. But make
8697 sure two decls are not the same. */
8711 {
8716 }
8717 /* For equal offsets we can simplify to a comparison of the
8718 base addresses. */
8720 && (indirect_base0
8722 && (indirect_base1
8727 {
8733 }
8734 }
8736 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8737 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8738 the resulting offset is smaller in absolute value than the
8739 original one. */
8747 {
8752 tree cst;
8754 "occur when combining constants around "
8757 /* Put the constant on the side where it doesn't overflow and is
8758 of lower absolute value than before. */
8764 {
8767 variable1,
8770 }
8777 {
8782 variable2);
8783 }
8784 }
8786 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8787 signed arithmetic case. That form is created by the compiler
8788 often enough for folding it to be of value. One example is in
8789 computing loop trip counts after Operator Strength Reduction. */
8795 {
8804 "eliminating multiplication in comparison "
8806 WARN_STRICT_OVERFLOW_COMPARISON);
8808 /* If const1 is negative we swap the sense of the comparison. */
8813 }
8820 {
8828 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8833 /* (-a) CMP (-b) -> b CMP a */
8840 {
8841 REAL_VALUE_TYPE cst;
8844 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8851 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8852 /* a CMP (-0) -> a CMP 0 */
8857 /* x != NaN is always true, other ops are always false. */
8860 {
8863 }
8865 /* Fold comparisons against infinity. */
8867 {
8871 }
8872 }
8874 /* If this is a comparison of a real constant with a PLUS_EXPR
8875 or a MINUS_EXPR of a real constant, we can convert it into a
8876 comparison with a revised real constant as long as no overflow
8877 occurs when unsafe_math_optimizations are enabled. */
8889 /* Likewise, we can simplify a comparison of a real constant with
8890 a MINUS_EXPR whose first operand is also a real constant, i.e.
8891 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
8892 floating-point types only if -fassociative-math is set. */
8903 /* Fold comparisons against built-in math functions. */
8905 && flag_unsafe_math_optimizations
8907 {
8911 {
8915 }
8916 }
8917 }
8921 {
8922 /* If we are widening one operand of an integer comparison,
8923 see if the other operand is similarly being widened. Perhaps we
8924 can do the comparison in the narrower type. */
8929 /* Or if we are changing signedness. */
8933 }
8935 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8936 constant, we can simplify it. */
8941 {
8945 }
8947 /* Simplify comparison of something with itself. (For IEEE
8948 floating-point, we can only do some of these simplifications.) */
8950 {
8952 {
8967 /* For NE, we can only do this simplification if integer
8968 or we don't honor IEEE floating point NaNs. */
8972 /* ... fall through ... */
8978 }
8979 }
8981 /* If we are comparing an expression that just has comparisons
8982 of two integer values, arithmetic expressions of those comparisons,
8983 and constants, we can simplify it. There are only three cases
8984 to check: the two values can either be equal, the first can be
8985 greater, or the second can be greater. Fold the expression for
8986 those three values. Since each value must be 0 or 1, we have
8987 eight possibilities, each of which corresponds to the constant 0
8988 or 1 or one of the six possible comparisons.
8990 This handles common cases like (a > b) == 0 but also handles
8991 expressions like ((x > y) - (y > x)) > 0, which supposedly
8992 occur in macroized code. */
8995 {
9000 /* Don't handle degenerate cases here; they should already
9001 have been handled anyway. */
9010 {
9014 /* We can't just pass T to eval_subst in case cval1 or cval2
9015 was the same as ARG1. */
9017 tree high_result
9021 arg1);
9022 tree equal_result
9026 arg1);
9027 tree low_result
9031 arg1);
9033 /* All three of these results should be 0 or 1. Confirm they are.
9034 Then use those values to select the proper code to use. */
9039 {
9040 /* Make a 3-bit mask with the high-order bit being the
9041 value for `>', the next for '=', and the low for '<'. */
9045 {
9047 /* Always false. */
9068 /* Always true. */
9070 }
9075 }
9076 }
9077 }
9079 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9080 into a single range test. */
9088 {
9092 }
9094 /* Fold ~X op ~Y as Y op X. */
9097 {
9102 }
9104 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9107 {
9113 }
9116 }
9119 /* Subroutine of fold_binary. Optimize complex multiplications of the
9120 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9121 argument EXPR represents the expression "z" of type TYPE. */
9123 static tree
9125 {
9130 {
9133 }
9135 {
9138 }
9139 else
9140 {
9144 }
9153 }
9156 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9157 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9158 guarantees that P and N have the same least significant log2(M) bits.
9159 N is not otherwise constrained. In particular, N is not normalized to
9160 0 <= N < M as is common. In general, the precise value of P is unknown.
9161 M is chosen as large as possible such that constant N can be determined.
9163 Returns M and sets *RESIDUE to N. */
9165 static unsigned HOST_WIDE_INT
9167 {
9174 {
9177 {
9179 tree offset;
9187 {
9190 else
9191 /* We don't handle more complicated offset expressions. */
9193 }
9194 }
9198 }
9200 {
9213 {
9216 }
9218 {
9221 {
9224 /* Compute the greatest power-of-2 divisor of op1. */
9228 /* If align is non-zero and less than *modulus, replace
9229 *modulus with align., If align is 0, then either op1 is 0
9230 or the greatest power-of-2 divisor of op1 doesn't fit in an
9231 unsigned HOST_WIDE_INT. In either case, no additional
9232 constraint is imposed. */
9237 }
9238 }
9239 }
9241 /* If we get here, we were unable to determine anything useful about the
9242 expression. */
9244 }
9247 /* Fold a binary expression of code CODE and type TYPE with operands
9248 OP0 and OP1. Return the folded expression if folding is
9249 successful. Otherwise, return NULL_TREE. */
9251 tree
9253 {
9267 /* Strip any conversions that don't change the mode. This is
9268 safe for every expression, except for a comparison expression
9269 because its signedness is derived from its operands. So, in
9270 the latter case, only strip conversions that don't change the
9271 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9272 preserved.
9274 Note that this is done as an internal manipulation within the
9275 constant folder, in order to find the simplest representation
9276 of the arguments so that their form can be studied. In any
9277 cases, the appropriate type conversions should be put back in
9278 the tree that will get out of the constant folder. */
9281 {
9284 }
9285 else
9286 {
9289 }
9291 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9292 constant but we can't do arithmetic on them. */
9299 {
9301 {
9302 /* Make sure type and arg0 have the same saturating flag. */
9306 }
9309 else
9313 {
9317 }
9318 }
9320 /* If this is a commutative operation, and ARG0 is a constant, move it
9321 to ARG1 to reduce the number of tests below. */
9326 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9328 First check for cases where an arithmetic operation is applied to a
9329 compound, conditional, or comparison operation. Push the arithmetic
9330 operation inside the compound or conditional to see if any folding
9331 can then be done. Convert comparison to conditional for this purpose.
9332 The also optimizes non-constant cases that used to be done in
9333 expand_expr.
9335 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9336 one of the operands is a comparison and the other is a comparison, a
9337 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9338 code below would make the expression more complex. Change it to a
9339 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9340 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9352 {
9356 boolean_type_node,
9364 }
9368 {
9374 op1));
9383 {
9389 }
9392 {
9398 }
9399 }
9402 {
9404 /* 0 +p index -> (type)index */
9408 /* PTR +p 0 -> PTR */
9412 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9419 /* index +p PTR -> PTR +p index */
9426 /* (PTR +p B) +p A -> PTR +p (B + A) */
9428 {
9429 tree inner;
9437 }
9439 /* PTR_CST +p CST -> CST1 */
9443 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9444 of the array. Loop optimizer sometimes produce this type of
9445 expressions. */
9447 {
9451 }
9456 /* PTR + INT -> (INT)(PTR p+ INT) */
9461 arg0,
9463 /* INT + PTR -> (INT)(PTR p+ INT) */
9468 arg1,
9470 /* A + (-B) -> A - B */
9475 /* (-A) + B -> B - A */
9483 {
9484 /* Convert ~A + 1 to -A. */
9489 /* ~X + X is -1. */
9492 {
9497 {
9500 }
9501 }
9503 /* X + ~X is -1. */
9506 {
9511 {
9514 }
9515 }
9517 /* X + (X / CST) * -CST is X % CST. */
9522 {
9530 }
9531 }
9533 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9534 same or one. Make sure type is not saturating.
9535 fold_plusminus_mult_expr will re-associate. */
9540 {
9544 }
9547 {
9551 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9552 with a constant, and the two constants have no bits in common,
9553 we should treat this as a BIT_IOR_EXPR since this may produce more
9554 simplifications. */
9562 {
9565 }
9567 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9568 (plus (plus (mult) (mult)) (foo)) so that we can
9569 take advantage of the factoring cases below. */
9576 {
9582 else
9604 parg1)));
9605 }
9606 }
9607 else
9608 {
9609 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9613 /* Likewise if the operands are reversed. */
9617 /* Convert X + -C into X - C. */
9620 {
9626 }
9628 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9629 to __complex__ ( x, y ). This is not the same for SNaNs or
9630 if signed zeros are involved. */
9634 {
9641 {
9645 {
9651 }
9653 {
9659 }
9660 }
9661 }
9669 /* Convert x+x into x*2.0. */
9675 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9676 We associate floats only if the user has specified
9677 -fassociative-math. */
9681 {
9686 {
9687 tree tree0;
9690 }
9691 }
9692 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9693 We associate floats only if the user has specified
9694 -fassociative-math. */
9698 {
9703 {
9704 tree tree0;
9707 }
9708 }
9709 }
9711 bit_rotate:
9712 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9713 is a rotate of A by C1 bits. */
9714 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9715 is a rotate of A by B bits. */
9716 {
9718 tree rtype;
9727 /* Only create rotates in complete modes. Other cases are not
9728 expanded properly. */
9730 {
9749 {
9757 TYPE_PRECISION
9762 ? LROTATE_EXPR
9765 }
9767 {
9775 TYPE_PRECISION
9780 ? LROTATE_EXPR
9783 }
9784 }
9785 }
9787 associate:
9788 /* In most languages, can't associate operations on floats through
9789 parentheses. Rather than remember where the parentheses were, we
9790 don't associate floats at all, unless the user has specified
9791 -fassociative-math.
9792 And, we need to make sure type is not saturating. */
9796 {
9801 /* Split both trees into variables, constants, and literals. Then
9802 associate each group together, the constants with literals,
9803 then the result with variables. This increases the chances of
9804 literals being recombined later and of generating relocatable
9805 expressions for the sum of a constant and literal. */
9810 /* With undefined overflow we can only associate constants
9811 with one variable. */
9815 {
9823 /* The only case we can still associate with two variables
9824 is if they are the same, modulo negation. */
9827 }
9829 /* Only do something if we found more than two objects. Otherwise,
9830 nothing has changed and we risk infinite recursion. */
9836 {
9837 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9846 /* Preserve the MINUS_EXPR if the negative part of the literal is
9847 greater than the positive part. Otherwise, the multiplicative
9848 folding code (i.e extract_muldiv) may be fooled in case
9849 unsigned constants are subtracted, like in the following
9850 example: ((X*2 + 4) - 8U)/2. */
9852 {
9856 {
9860 }
9861 else
9862 {
9866 }
9867 }
9869 {
9874 else
9875 {
9881 }
9882 }
9887 }
9888 }
9893 /* Pointer simplifications for subtraction, simple reassociations. */
9895 {
9896 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
9899 {
9907 }
9908 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
9910 {
9916 }
9917 }
9918 /* A - (-B) -> A + B */
9922 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9931 /* Convert -A - 1 to ~A. */
9939 /* Convert -1 - A to ~A. */
9945 /* X - (X / CST) * CST is X % CST. */
9958 {
9964 /* Fold A - (A & B) into ~B & A. */
9967 {
9969 {
9974 }
9976 {
9981 }
9982 }
9984 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9985 any power of 2 minus 1. */
9990 {
9996 {
10000 }
10001 }
10002 }
10004 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10008 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10009 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10010 (-ARG1 + ARG0) reduces to -ARG1. */
10014 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10015 __complex__ ( x, -y ). This is not the same for SNaNs or if
10016 signed zeros are involved. */
10020 {
10027 {
10031 {
10033 arg1r ? arg1r
10038 }
10040 {
10044 arg1i ? arg1i
10047 }
10048 }
10049 }
10051 /* Fold &x - &x. This can happen from &x.foo - &x.
10052 This is unsafe for certain floats even in non-IEEE formats.
10053 In IEEE, it is unsafe because it does wrong for NaNs.
10054 Also note that operand_equal_p is always false if an operand
10055 is volatile. */
10061 /* A - B -> A + (-B) if B is easily negatable. */
10064 /* Avoid this transformation if B is a positive REAL_CST. */
10072 /* Try folding difference of addresses. */
10073 {
10074 HOST_WIDE_INT diff;
10080 }
10082 /* Fold &a[i] - &a[j] to i-j. */
10087 {
10092 {
10100 }
10101 }
10109 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10110 same or one. Make sure type is not saturating.
10111 fold_plusminus_mult_expr will re-associate. */
10116 {
10120 }
10125 /* (-A) * (-B) -> A * B */
10136 {
10141 /* Transform x * -1 into -x. Make sure to do the negation
10142 on the original operand with conversions not stripped
10143 because we can only strip non-sign-changing conversions. */
10146 /* Transform x * -C into -x * C if x is easily negatable. */
10155 /* (a * (1 << b)) is (a << b) */
10165 /* (A + A) * C -> A * 2 * C */
10180 {
10183 "occur when simplifying "
10185 WARN_STRICT_OVERFLOW_MISC);
10187 }
10189 /* Optimize z * conj(z) for integer complex numbers. */
10196 }
10197 else
10198 {
10199 /* Maybe fold x * 0 to 0. The expressions aren't the same
10200 when x is NaN, since x * 0 is also NaN. Nor are they the
10201 same in modes with signed zeros, since multiplying a
10202 negative value by 0 gives -0, not +0. */
10207 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10212 /* Transform x * -1.0 into -x. */
10217 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10218 the result for floating point types due to rounding so it is applied
10219 only if -fassociative-math was specify. */
10224 {
10230 }
10232 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10234 {
10237 {
10240 }
10241 }
10243 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10244 This is not the same for NaNs or if signed zeros are
10245 involved. */
10251 {
10263 }
10265 /* Optimize z * conj(z) for floating point complex numbers.
10266 Guarded by flag_unsafe_math_optimizations as non-finite
10267 imaginary components don't produce scalar results. */
10278 {
10282 /* Optimizations of root(...)*root(...). */
10284 {
10289 /* Optimize sqrt(x)*sqrt(x) as x. */
10295 /* Optimize root(x)*root(y) as root(x*y). */
10299 }
10301 /* Optimize expN(x)*expN(y) as expN(x+y). */
10303 {
10309 }
10311 /* Optimizations of pow(...)*pow(...). */
10315 {
10321 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10323 {
10327 }
10329 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10331 {
10335 }
10336 }
10338 /* Optimize tan(x)*cos(x) as sin(x). */
10347 {
10352 }
10354 /* Optimize x*pow(x,c) as pow(x,c+1). */
10358 {
10364 {
10366 REAL_VALUE_TYPE c;
10367 tree arg;
10373 }
10374 }
10376 /* Optimize pow(x,c)*x as pow(x,c+1). */
10380 {
10386 {
10388 REAL_VALUE_TYPE c;
10389 tree arg;
10395 }
10396 }
10398 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10401 {
10405 {
10408 }
10409 }
10410 }
10411 }
10415 bit_ior:
10423 /* ~X | X is -1. */
10426 {
10430 }
10432 /* X | ~X is -1. */
10435 {
10439 }
10441 /* Canonicalize (X & C1) | C2. */
10445 {
10453 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10458 {
10462 }
10463 else
10464 {
10468 }
10470 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10475 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10476 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10477 mode which allows further optimizations. */
10487 {
10488 unsigned HOST_WIDE_INT mask
10492 {
10496 }
10497 }
10504 arg1);
10505 }
10507 /* (X & Y) | Y is (X, Y). */
10511 /* (X & Y) | X is (Y, X). */
10516 /* X | (X & Y) is (Y, X). */
10521 /* X | (Y & X) is (Y, X). */
10531 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10533 This results in more efficient code for machines without a NAND
10534 instruction. Combine will canonicalize to the first form
10535 which will allow use of NAND instructions provided by the
10536 backend if they exist. */
10539 {
10546 }
10548 /* See if this can be simplified into a rotate first. If that
10549 is unsuccessful continue in the association code. */
10560 /* ~X ^ X is -1. */
10563 {
10567 }
10569 /* X ^ ~X is -1. */
10572 {
10576 }
10578 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10579 with a constant, and the two constants have no bits in common,
10580 we should treat this as a BIT_IOR_EXPR since this may produce more
10581 simplifications. */
10589 {
10592 }
10594 /* (X | Y) ^ X -> Y & ~ X*/
10597 {
10600 arg1);
10604 }
10606 /* (Y | X) ^ X -> Y & ~ X*/
10609 {
10612 arg1);
10616 }
10618 /* X ^ (X | Y) -> Y & ~ X*/
10621 {
10624 arg0);
10628 }
10630 /* X ^ (Y | X) -> Y & ~ X*/
10633 {
10636 arg0);
10640 }
10642 /* Convert ~X ^ ~Y to X ^ Y. */
10649 /* Convert ~X ^ C to X ^ ~C. */
10656 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10663 /* Fold (X & Y) ^ Y as ~X & Y. */
10666 {
10671 }
10672 /* Fold (X & Y) ^ X as ~Y & X. */
10676 {
10681 }
10682 /* Fold X ^ (X & Y) as X & ~Y. */
10685 {
10690 }
10691 /* Fold X ^ (Y & X) as ~Y & X. */
10695 {
10700 }
10702 /* See if this can be simplified into a rotate first. If that
10703 is unsuccessful continue in the association code. */
10714 /* ~X & X is always zero. */
10719 /* X & ~X is always zero. */
10724 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10728 {
10737 }
10739 /* (X | Y) & Y is (X, Y). */
10743 /* (X | Y) & X is (Y, X). */
10748 /* X & (X | Y) is (Y, X). */
10753 /* X & (Y | X) is (Y, X). */
10759 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10763 {
10769 }
10770 /* Fold ~X & 1 as (X & 1) == 0. */
10773 {
10779 }
10781 /* Fold (X ^ Y) & Y as ~X & Y. */
10784 {
10789 }
10790 /* Fold (X ^ Y) & X as ~Y & X. */
10794 {
10799 }
10800 /* Fold X & (X ^ Y) as X & ~Y. */
10803 {
10808 }
10809 /* Fold X & (Y ^ X) as ~Y & X. */
10813 {
10818 }
10823 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10826 {
10827 unsigned int prec
10834 }
10836 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10838 This results in more efficient code for machines without a NOR
10839 instruction. Combine will canonicalize to the first form
10840 which will allow use of NOR instructions provided by the
10841 backend if they exist. */
10844 {
10851 }
10853 /* If arg0 is derived from the address of an object or function, we may
10854 be able to fold this expression using the object or function's
10855 alignment. */
10857 {
10863 /* This works because modulus is a power of 2. If this weren't the
10864 case, we'd have to replace it by its greatest power-of-2
10865 divisor: modulus & -modulus. */
10868 }
10870 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
10871 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
10872 if the new mask might be further optimized. */
10881 {
10883 unsigned HOST_WIDE_INT mask
10893 {
10896 /* See if more bits can be proven as zero because of
10897 zero extension. */
10900 {
10905 {
10907 /* See if we can shorten the right shift. */
10910 }
10911 }
10915 /* For arithmetic shift if sign bit could be set, zerobits
10916 can contain actually sign bits, so no transformation is
10917 possible, unless MASK masks them all away. In that
10918 case the shift needs to be converted into logical shift. */
10921 {
10924 else
10926 }
10927 }
10929 /* ((X << 16) & 0xff00) is (X, 0). */
10935 {
10938 /* Only do the transformation if NEWMASK is some integer
10939 mode's mask. */
10946 {
10948 {
10954 }
10955 else
10959 newmask));
10960 }
10961 }
10962 }
10967 /* Don't touch a floating-point divide by zero unless the mode
10968 of the constant can represent infinity. */
10974 /* Optimize A / A to 1.0 if we don't care about
10975 NaNs or Infinities. Skip the transformation
10976 for non-real operands. */
10981 {
10985 }
10987 /* The complex version of the above A / A optimization. */
10990 {
10994 {
10996 /* omit_two_operands will call fold_convert for us. */
10998 }
10999 }
11001 /* (-A) / (-B) -> A / B */
11011 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11016 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11021 /* If ARG1 is a constant, we can convert this to a multiply by the
11022 reciprocal. This does not have the same rounding properties,
11023 so only do this if -freciprocal-math. We can actually
11024 always safely do it if ARG1 is a power of two, but it's hard to
11025 tell if it is or not in a portable manner. */
11027 {
11032 /* Find the reciprocal if optimizing and the result is exact. */
11034 {
11035 REAL_VALUE_TYPE r;
11038 {
11042 }
11043 }
11044 }
11045 /* Convert A/B/C to A/(B*C). */
11052 /* Convert A/(B/C) to (A/B)*C. */
11060 /* Convert C1/(X*C2) into (C1/C2)/X. */
11065 {
11071 }
11074 {
11078 /* Optimize sin(x)/cos(x) as tan(x). */
11084 {
11089 }
11091 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11097 {
11101 {
11105 }
11106 }
11108 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11109 NaNs or Infinities. */
11113 {
11120 {
11125 }
11126 }
11128 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11129 NaNs or Infinities. */
11133 {
11140 {
11144 {
11148 tmp);
11149 }
11150 }
11151 }
11153 /* Optimize pow(x,c)/x as pow(x,c-1). */
11157 {
11163 {
11165 REAL_VALUE_TYPE c;
11166 tree arg;
11172 }
11173 }
11175 /* Optimize a/root(b/c) into a*root(c/b). */
11177 {
11181 {
11190 }
11191 }
11193 /* Optimize x/expN(y) into x*expN(-y). */
11195 {
11200 }
11202 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11206 {
11213 }
11214 }
11219 /* Simplify A / (B << N) where A and B are positive and B is
11220 a power of 2, to A >> (N + log2(B)). */
11225 {
11228 {
11235 WARN_STRICT_OVERFLOW_MISC);
11241 }
11242 }
11244 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11245 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11251 /* Fall thru */
11260 /* X / -1 is -X. */
11267 /* Convert -A / -B to A / B when the type is signed and overflow is
11268 undefined. */
11272 {
11275 "when distributing negation across "
11277 WARN_STRICT_OVERFLOW_MISC);
11281 }
11285 {
11288 "when distributing negation across "
11290 WARN_STRICT_OVERFLOW_MISC);
11293 }
11295 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11296 operation, EXACT_DIV_EXPR.
11298 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11299 At one time others generated faster code, it's not clear if they do
11300 after the last round to changes to the DIV code in expmed.c. */
11309 {
11313 WARN_STRICT_OVERFLOW_MISC);
11315 }
11323 /* X % 1 is always zero, but be sure to preserve any side
11324 effects in X. */
11328 /* X % 0, return X % 0 unchanged so that we can get the
11329 proper warnings and errors. */
11333 /* 0 % X is always zero, but be sure to preserve any side
11334 effects in X. Place this after checking for X == 0. */
11338 /* X % -1 is zero. */
11345 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11346 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11351 {
11353 /* Also optimize A % (C << N) where C is a power of 2,
11354 to A & ((C << N) - 1). */
11359 {
11364 "occur when simplifying "
11366 WARN_STRICT_OVERFLOW_MISC);
11370 }
11371 }
11373 /* X % -C is the same as X % C. */
11380 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11385 /* X % -Y is the same as X % Y. */
11396 {
11400 WARN_STRICT_OVERFLOW_MISC);
11402 }
11413 /* Optimize -1 >> x for arithmetic right shifts. */
11416 /* ... fall through ... */
11419 shift:
11425 /* Since negative shift count is not well-defined,
11426 don't try to compute it in the compiler. */
11430 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11435 {
11439 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11440 being well defined. */
11442 {
11447 else
11449 }
11453 }
11455 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11456 into x & ((unsigned)-1 >> c) for unsigned types. */
11464 {
11467 tree lshift;
11468 tree arg00;
11471 {
11478 }
11479 }
11481 /* Rewrite an LROTATE_EXPR by a constant into an
11482 RROTATE_EXPR by a new constant. */
11484 {
11489 }
11491 /* If we have a rotate of a bit operation with the rotate count and
11492 the second operand of the bit operation both constant,
11493 permute the two operations. */
11505 /* Two consecutive rotates adding up to the precision of the
11506 type can be ignored. */
11517 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11518 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11519 if the latter can be further optimized. */
11524 {
11527 arg1);
11530 arg1);
11534 }
11562 /* Note that the operands of this must be ints
11563 and their values must be 0 or 1.
11564 ("true" is a fixed value perhaps depending on the language.) */
11565 /* If first arg is constant zero, return it. */
11569 /* If either arg is constant true, drop it. */
11573 /* Preserve sequence points. */
11576 /* If second arg is constant zero, result is zero, but first arg
11577 must be evaluated. */
11580 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11581 case will be handled here. */
11585 /* !X && X is always false. */
11589 /* X && !X is always false. */
11594 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
11595 means A >= Y && A != MAX, but in this case we know that
11596 A < X <= MAX. */
11600 {
11608 }
11610 truth_andor:
11611 /* We only do these simplifications if we are optimizing. */
11615 /* Check for things like (A || B) && (A || C). We can convert this
11616 to A || (B && C). Note that either operator can be any of the four
11617 truth and/or operations and the transformation will still be
11618 valid. Also note that we only care about order for the
11619 ANDIF and ORIF operators. If B contains side effects, this
11620 might change the truth-value of A. */
11627 {
11647 /* This case if tricky because we must either have commutative
11648 operators or else A10 must not have side-effects. */
11654 a01);
11655 }
11657 /* See if we can build a range comparison. */
11661 /* Check for the possibility of merging component references. If our
11662 lhs is another similar operation, try to merge its rhs with our
11663 rhs. Then try to merge our lhs and rhs. */
11675 /* Note that the operands of this must be ints
11676 and their values must be 0 or true.
11677 ("true" is a fixed value perhaps depending on the language.) */
11678 /* If first arg is constant true, return it. */
11682 /* If either arg is constant zero, drop it. */
11686 /* Preserve sequence points. */
11689 /* If second arg is constant true, result is true, but we must
11690 evaluate first arg. */
11693 /* Likewise for first arg, but note this only occurs here for
11694 TRUTH_OR_EXPR. */
11698 /* !X || X is always true. */
11702 /* X || !X is always true. */
11710 /* If the second arg is constant zero, drop it. */
11713 /* If the second arg is constant true, this is a logical inversion. */
11715 {
11716 /* Only call invert_truthvalue if operand is a truth value. */
11719 else
11722 }
11723 /* Identical arguments cancel to zero. */
11727 /* !X ^ X is always true. */
11732 /* X ^ !X is always true. */
11745 /* bool_var != 0 becomes bool_var. */
11750 /* bool_var == 1 becomes bool_var. */
11755 /* bool_var != 1 becomes !bool_var. */
11760 /* bool_var == 0 becomes !bool_var. */
11765 /* If this is an equality comparison of the address of two non-weak,
11766 unaliased symbols neither of which are extern (since we do not
11767 have access to attributes for externs), then we know the result. */
11780 {
11781 /* We know that we're looking at the address of two
11782 non-weak, unaliased, static _DECL nodes.
11784 It is both wasteful and incorrect to call operand_equal_p
11785 to compare the two ADDR_EXPR nodes. It is wasteful in that
11786 all we need to do is test pointer equality for the arguments
11787 to the two ADDR_EXPR nodes. It is incorrect to use
11788 operand_equal_p as that function is NOT equivalent to a
11789 C equality test. It can in fact return false for two
11790 objects which would test as equal using the C equality
11791 operator. */
11795 type);
11796 }
11798 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
11799 a MINUS_EXPR of a constant, we can convert it into a comparison with
11800 a revised constant as long as no overflow occurs. */
11812 /* Similarly for a NEGATE_EXPR. */
11820 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11829 /* Transform comparisons of the form X +- C CMP X. */
11835 {
11842 else
11845 }
11847 /* If we have X - Y == 0, we can convert that to X == Y and similarly
11848 for !=. Don't do this for ordered comparisons due to overflow. */
11854 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11859 /* If this is an EQ or NE comparison with zero and ARG0 is
11860 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11861 two operations, but the latter can be done in one less insn
11862 on machines that have only two-operand insns or on which a
11863 constant cannot be the first operand. */
11866 {
11871 {
11878 }
11881 {
11888 }
11889 }
11891 /* If this is an NE or EQ comparison of zero against the result of a
11892 signed MOD operation whose second operand is a power of 2, make
11893 the MOD operation unsigned since it is simpler and equivalent. */
11901 {
11911 }
11913 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11914 C1 is a valid shift constant, and C2 is a power of two, i.e.
11915 a single bit. */
11919 == INTEGER_CST
11922 {
11927 /* Check for a valid shift count. */
11930 {
11934 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11935 can be rewritten as (X & (C2 << C1)) != 0. */
11937 {
11941 }
11942 /* Otherwise, for signed (arithmetic) shifts,
11943 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11944 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11948 /* Otherwise, of unsigned (logical) shifts,
11949 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11950 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11951 else
11955 arg000);
11956 }
11957 }
11959 /* If this is an NE comparison of zero with an AND of one, remove the
11960 comparison since the AND will give the correct value. */
11967 /* If we have (A & C) == C where C is a power of 2, convert this into
11968 (A & C) != 0. Similarly for NE_EXPR. */
11974 integer_zero_node));
11976 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11977 bit, then fold the expression into A < 0 or A >= 0. */
11982 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11983 Similarly for NE_EXPR. */
11987 {
11996 }
11998 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11999 Similarly for NE_EXPR. */
12003 {
12010 }
12012 /* Optimize comparisons of strlen vs zero to a compare of the
12013 first character of the string vs zero. To wit,
12014 strlen(ptr) == 0 => *ptr == 0
12015 strlen(ptr) != 0 => *ptr != 0
12016 Other cases should reduce to one of these two (or a constant)
12017 due to the return value of strlen being unsigned. */
12020 {
12028 {
12032 }
12033 }
12035 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12036 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12040 {
12047 {
12049 {
12052 }
12055 }
12056 }
12058 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12064 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12069 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12076 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12084 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12085 (X & C) == 0 when C is a single bit. */
12090 {
12096 }
12098 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12099 constant C is a power of two, i.e. a single bit. */
12106 {
12110 }
12112 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12113 when is C is a power of two, i.e. a single bit. */
12120 {
12126 }
12130 {
12133 }
12135 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12142 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12145 {
12157 arg01),
12165 arg01),
12173 arg00),
12181 arg00),
12183 }
12187 {
12194 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12195 operand_equal_p guarantees no side-effects so we don't need
12196 to use omit_one_operand on Z. */
12206 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12213 arg10);
12214 }
12216 /* Attempt to simplify equality/inequality comparisons of complex
12217 values. Only lower the comparison if the result is known or
12218 can be simplified to a single scalar comparison. */
12223 {
12228 {
12231 }
12232 else
12233 {
12236 }
12239 {
12242 }
12243 else
12244 {
12247 }
12251 {
12253 {
12258 }
12259 else
12260 {
12265 }
12266 }
12270 {
12272 {
12277 }
12278 else
12279 {
12284 }
12285 }
12286 }
12298 /* Transform comparisons of the form X +- C CMP X. */
12305 {
12312 else
12315 /* (X - c) > X becomes false. */
12319 {
12323 "occur when assuming that (X - c) > X "
12325 WARN_STRICT_OVERFLOW_ALL);
12327 }
12329 /* Likewise (X + c) < X becomes false. */
12333 {
12337 "occur when assuming that "
12339 WARN_STRICT_OVERFLOW_ALL);
12341 }
12343 /* Convert (X - c) <= X to true. */
12348 {
12352 "occur when assuming that "
12354 WARN_STRICT_OVERFLOW_ALL);
12356 }
12358 /* Convert (X + c) >= X to true. */
12363 {
12367 "occur when assuming that "
12369 WARN_STRICT_OVERFLOW_ALL);
12371 }
12374 {
12375 /* Convert X + c > X and X - c < X to true for integers. */
12379 {
12382 "not occur when assuming that "
12384 WARN_STRICT_OVERFLOW_ALL);
12386 }
12391 {
12394 "not occur when assuming that "
12396 WARN_STRICT_OVERFLOW_ALL);
12398 }
12400 /* Convert X + c <= X and X - c >= X to false for integers. */
12404 {
12407 "not occur when assuming that "
12409 WARN_STRICT_OVERFLOW_ALL);
12411 }
12416 {
12419 "not occur when assuming that "
12421 WARN_STRICT_OVERFLOW_ALL);
12423 }
12424 }
12425 }
12427 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
12428 This transformation affects the cases which are handled in later
12429 optimizations involving comparisons with non-negative constants. */
12433 {
12435 {
12440 }
12442 {
12447 }
12448 }
12450 /* Comparisons with the highest or lowest possible integer of
12451 the specified precision will have known values. */
12452 {
12460 {
12461 HOST_WIDE_INT signed_max_hi;
12466 {
12473 {
12477 }
12478 else
12479 {
12483 }
12484 }
12485 else
12486 {
12495 {
12498 }
12499 else
12500 {
12503 }
12504 }
12509 {
12522 /* The GE_EXPR and LT_EXPR cases above are not normally
12523 reached because of previous transformations. */
12527 }
12529 == max_hi
12532 {
12538 arg1);
12544 arg1);
12547 }
12549 == min_hi
12552 {
12567 }
12569 == min_hi
12572 {
12577 arg1);
12582 arg1);
12585 }
12590 /* We will flip the signedness of the comparison operator
12591 associated with the mode of arg1, so the sign bit is
12592 specified by this mode. Check that arg1 is the signed
12593 max associated with this sign bit. */
12595 /* signed_type does not work on pointer types. */
12597 {
12598 /* The following case also applies to X < signed_max+1
12599 and X >= signed_max+1 because previous transformations. */
12601 {
12602 tree st;
12607 }
12608 }
12609 }
12610 }
12612 /* If we are comparing an ABS_EXPR with a constant, we can
12613 convert all the cases into explicit comparisons, but they may
12614 well not be faster than doing the ABS and one comparison.
12615 But ABS (X) <= C is a range comparison, which becomes a subtraction
12616 and a comparison, and is probably faster. */
12630 /* Convert ABS_EXPR<x> >= 0 to true. */
12637 {
12640 "when simplifying comparison of "
12642 WARN_STRICT_OVERFLOW_CONDITIONAL);
12644 }
12646 /* Convert ABS_EXPR<x> < 0 to false. */
12651 {
12654 "when simplifying comparison of "
12656 WARN_STRICT_OVERFLOW_CONDITIONAL);
12658 }
12660 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12661 and similarly for >= into !=. */
12676 return
12695 {
12699 }
12701 /* If the first operand is NaN, the result is constant. */
12705 {
12707 ? integer_zero_node
12710 }
12712 /* If the second operand is NaN, the result is constant. */
12716 {
12718 ? integer_zero_node
12721 }
12723 /* Simplify unordered comparison of something with itself. */
12729 && !flag_trapping_math
12733 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12734 {
12745 }
12750 /* When pedantic, a compound expression can be neither an lvalue
12751 nor an integer constant expression. */
12754 /* Don't let (0, 0) be null pointer constant. */
12768 /* An ASSERT_EXPR should never be passed to fold_binary. */
12774 }
12776 /* Callback for walk_tree, looking for LABEL_EXPR.
12777 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
12778 Do not check the sub-tree of GOTO_EXPR. */
12780 static tree
12784 {
12786 {
12791 /* no break */
12794 }
12795 }
12797 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
12798 accessible from outside the sub-tree. Returns NULL_TREE if no
12799 addressable label is found. */
12801 static bool
12803 {
12805 }
12807 /* Fold a ternary expression of code CODE and type TYPE with operands
12808 OP0, OP1, and OP2. Return the folded expression if folding is
12809 successful. Otherwise, return NULL_TREE. */
12811 tree
12813 {
12814 tree tem;
12821 /* Strip any conversions that don't change the mode. This is safe
12822 for every expression, except for a comparison expression because
12823 its signedness is derived from its operands. So, in the latter
12824 case, only strip conversions that don't change the signedness.
12826 Note that this is done as an internal manipulation within the
12827 constant folder, in order to find the simplest representation of
12828 the arguments so that their form can be studied. In any cases,
12829 the appropriate type conversions should be put back in the tree
12830 that will get out of the constant folder. */
12832 {
12835 }
12838 {
12841 }
12844 {
12848 {
12854 }
12858 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12859 so all simple results must be passed through pedantic_non_lvalue. */
12861 {
12864 /* Only optimize constant conditions when the selected branch
12865 has the same type as the COND_EXPR. This avoids optimizing
12866 away "c ? x : throw", where the throw has a void type.
12867 Avoid throwing away that operand which contains label. */
12874 }
12878 /* If we have A op B ? A : C, we may be able to convert this to a
12879 simpler expression, depending on the operation and the values
12880 of B and C. Signed zeros prevent all of these transformations,
12881 for reasons given above each one.
12883 Also try swapping the arguments and inverting the conditional. */
12888 {
12892 }
12896 op2,
12899 {
12902 {
12906 }
12907 }
12909 /* If the second operand is simpler than the third, swap them
12910 since that produces better jump optimization results. */
12913 {
12914 /* See if this can be inverted. If it can't, possibly because
12915 it was a floating-point inequality comparison, don't do
12916 anything. */
12920 }
12922 /* Convert A ? 1 : 0 to simply A. */
12925 /* If we try to convert OP0 to our type, the
12926 call to fold will try to move the conversion inside
12927 a COND, which will recurse. In that case, the COND_EXPR
12928 is probably the best choice, so leave it alone. */
12932 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12933 over COND_EXPR in cases such as floating point comparisons. */
12940 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12945 {
12946 /* sign_bit_p only checks ARG1 bits within A's precision.
12947 If <sign bit of A> has wider type than A, bits outside
12948 of A's precision in <sign bit of A> need to be checked.
12949 If they are all 0, this optimization needs to be done
12950 in unsigned A's type, if they are all 1 in signed A's type,
12951 otherwise this can't be done. */
12956 {
12958 HOST_WIDE_INT mask_hi;
12960 tree tem_type;
12968 {
12972 }
12973 else
12974 {
12978 }
12980 {
12984 }
12985 else
12991 {
12994 }
12997 {
13000 }
13001 else
13003 }
13010 arg1)));
13011 }
13013 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13014 already handled above. */
13019 {
13028 }
13030 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13031 is probably obsolete because the first operand should be a
13032 truth value (that's why we have the two cases above), but let's
13033 leave it in until we can confirm this for all front-ends. */
13044 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13050 arg1);
13052 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13056 {
13057 /* Only perform transformation if ARG0 is easily inverted. */
13062 arg1);
13063 }
13065 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13069 {
13070 /* Only perform transformation if ARG0 is easily inverted. */
13075 op2);
13076 }
13078 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13084 op2);
13089 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13090 of fold_ternary on them. */
13097 {
13106 {
13111 else
13112 {
13114 tree value;
13118 }
13123 else
13125 }
13126 }
13128 /* A bit-field-ref that referenced the full argument can be stripped. */
13139 }
13141 /* Perform constant folding and related simplification of EXPR.
13142 The related simplifications include x*1 => x, x*0 => 0, etc.,
13143 and application of the associative law.
13144 NOP_EXPR conversions may be removed freely (as long as we
13145 are careful not to change the type of the overall expression).
13146 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13147 but we can constant-fold them if they have constant operands. */
13149 #ifdef ENABLE_FOLD_CHECKING
13150 # define fold(x) fold_1 (x)
13152 static
13153 #endif
13154 tree
13156 {
13160 tree tem;
13162 /* Return right away if a constant. */
13166 /* CALL_EXPR-like objects with variable numbers of operands are
13167 treated specially. */
13169 {
13171 {
13174 }
13176 }
13179 {
13184 {
13202 }
13203 }
13206 {
13208 {
13215 {
13220 /* Find a matching index by means of a binary search. */
13222 {
13238 else
13240 }
13241 }
13244 }
13252 }
13254 #ifdef ENABLE_FOLD_CHECKING
13255 #undef fold
13261 /* When --enable-checking=fold, compute a digest of expr before
13262 and after actual fold call to see if fold did not accidentally
13263 change original expr. */
13265 tree
13267 {
13268 tree ret;
13271 htab_t ht;
13290 }
13292 void
13294 {
13297 htab_t ht;
13307 }
13309 static void
13311 {
13313 }
13315 static void
13317 {
13323 recursive_label:
13337 {
13338 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13342 }
13347 {
13348 /* Allow these fields to be modified. */
13349 tree tmp;
13356 {
13359 }
13360 }
13369 {
13372 {
13386 }
13390 {
13403 }
13420 {
13426 }
13431 {
13435 }
13446 {
13449 }
13459 }
13460 }
13462 /* Helper function for outputting the checksum of a tree T. When
13463 debugging with gdb, you can "define mynext" to be "next" followed
13464 by "call debug_fold_checksum (op0)", then just trace down till the
13465 outputs differ. */
13467 void
13469 {
13484 }
13486 #endif
13488 /* Fold a unary tree expression with code CODE of type TYPE with an
13489 operand OP0. Return a folded expression if successful. Otherwise,
13490 return a tree expression with code CODE of type TYPE with an
13491 operand OP0. */
13493 tree
13495 {
13496 tree tem;
13497 #ifdef ENABLE_FOLD_CHECKING
13500 htab_t ht;
13507 #endif
13513 #ifdef ENABLE_FOLD_CHECKING
13521 #endif
13523 }
13525 /* Fold a binary tree expression with code CODE of type TYPE with
13526 operands OP0 and OP1. Return a folded expression if successful.
13527 Otherwise, return a tree expression with code CODE of type TYPE
13528 with operands OP0 and OP1. */
13530 tree
13532 MEM_STAT_DECL)
13533 {
13534 tree tem;
13535 #ifdef ENABLE_FOLD_CHECKING
13541 htab_t ht;
13553 #endif
13559 #ifdef ENABLE_FOLD_CHECKING
13575 #endif
13577 }
13579 /* Fold a ternary tree expression with code CODE of type TYPE with
13580 operands OP0, OP1, and OP2. Return a folded expression if
13581 successful. Otherwise, return a tree expression with code CODE of
13582 type TYPE with operands OP0, OP1, and OP2. */
13584 tree
13586 MEM_STAT_DECL)
13587 {
13588 tree tem;
13589 #ifdef ENABLE_FOLD_CHECKING
13597 htab_t ht;
13614 #endif
13621 #ifdef ENABLE_FOLD_CHECKING
13645 #endif
13647 }
13649 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
13650 arguments in ARGARRAY, and a null static chain.
13651 Return a folded expression if successful. Otherwise, return a CALL_EXPR
13652 of type TYPE from the given operands as constructed by build_call_array. */
13654 tree
13656 {
13657 tree tem;
13658 #ifdef ENABLE_FOLD_CHECKING
13664 htab_t ht;
13678 #endif
13682 #ifdef ENABLE_FOLD_CHECKING
13699 #endif
13701 }
13703 /* Perform constant folding and related simplification of initializer
13704 expression EXPR. These behave identically to "fold_buildN" but ignore
13705 potential run-time traps and exceptions that fold must preserve. */
13707 #define START_FOLD_INIT \
13708 int saved_signaling_nans = flag_signaling_nans;\
13709 int saved_trapping_math = flag_trapping_math;\
13710 int saved_rounding_math = flag_rounding_math;\
13711 int saved_trapv = flag_trapv;\
13712 int saved_folding_initializer = folding_initializer;\
13713 flag_signaling_nans = 0;\
13714 flag_trapping_math = 0;\
13715 flag_rounding_math = 0;\
13716 flag_trapv = 0;\
13717 folding_initializer = 1;
13719 #define END_FOLD_INIT \
13720 flag_signaling_nans = saved_signaling_nans;\
13721 flag_trapping_math = saved_trapping_math;\
13722 flag_rounding_math = saved_rounding_math;\
13723 flag_trapv = saved_trapv;\
13724 folding_initializer = saved_folding_initializer;
13726 tree
13728 {
13729 tree result;
13730 START_FOLD_INIT;
13734 END_FOLD_INIT;
13736 }
13738 tree
13740 {
13741 tree result;
13742 START_FOLD_INIT;
13746 END_FOLD_INIT;
13748 }
13750 tree
13752 tree op2)
13753 {
13754 tree result;
13755 START_FOLD_INIT;
13759 END_FOLD_INIT;
13761 }
13763 tree
13766 {
13767 tree result;
13768 START_FOLD_INIT;
13772 END_FOLD_INIT;
13774 }
13776 #undef START_FOLD_INIT
13777 #undef END_FOLD_INIT
13779 /* Determine if first argument is a multiple of second argument. Return 0 if
13780 it is not, or we cannot easily determined it to be.
13782 An example of the sort of thing we care about (at this point; this routine
13783 could surely be made more general, and expanded to do what the *_DIV_EXPR's
13784 fold cases do now) is discovering that
13786 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13788 is a multiple of
13790 SAVE_EXPR (J * 8)
13792 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13794 This code also handles discovering that
13796 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13798 is a multiple of 8 so we don't have to worry about dealing with a
13799 possible remainder.
13801 Note that we *look* inside a SAVE_EXPR only to determine how it was
13802 calculated; it is not safe for fold to do much of anything else with the
13803 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13804 at run time. For example, the latter example above *cannot* be implemented
13805 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13806 evaluation time of the original SAVE_EXPR is not necessarily the same at
13807 the time the new expression is evaluated. The only optimization of this
13808 sort that would be valid is changing
13810 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13812 divided by 8 to
13814 SAVE_EXPR (I) * SAVE_EXPR (J)
13816 (where the same SAVE_EXPR (J) is used in the original and the
13817 transformed version). */
13819 int
13821 {
13829 {
13831 /* Bitwise and provides a power of two multiple. If the mask is
13832 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13835 /* FALLTHRU */
13848 {
13852 /* const_binop may not detect overflow correctly,
13853 so check for it explicitly here. */
13859 size_one_node,
13863 }
13867 /* Can't handle conversions from non-integral or wider integral type. */
13873 /* .. fall through ... */
13890 }
13891 }
13893 /* Return true if CODE or TYPE is known to be non-negative. */
13895 static bool
13897 {
13900 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
13901 have a signed:1 type (where the value is -1 and 0). */
13904 }
13906 /* Return true if (CODE OP0) is known to be non-negative. If the return
13907 value is based on the assumption that signed overflow is undefined,
13908 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13909 *STRICT_OVERFLOW_P. */
13911 bool
13914 {
13919 {
13921 /* We can't return 1 if flag_wrapv is set because
13922 ABS_EXPR<INT_MIN> = INT_MIN. */
13926 {
13929 }
13936 strict_overflow_p);
13939 {
13944 {
13947 strict_overflow_p);
13949 {
13953 strict_overflow_p);
13954 }
13955 }
13957 {
13960 strict_overflow_p);
13964 }
13965 }
13970 }
13972 /* We don't know sign of `t', so be conservative and return false. */
13974 }
13976 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
13977 value is based on the assumption that signed overflow is undefined,
13978 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13979 *STRICT_OVERFLOW_P. */
13981 bool
13984 {
13989 {
13994 strict_overflow_p)
13996 strict_overflow_p));
13998 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13999 both unsigned and at least 2 bits shorter than the result. */
14003 {
14008 {
14012 }
14013 }
14018 {
14019 /* x * x for floating point x is always non-negative. */
14023 strict_overflow_p)
14025 strict_overflow_p));
14026 }
14028 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14029 both unsigned and their total bits is shorter than the result. */
14033 {
14040 }
14046 strict_overflow_p)
14048 strict_overflow_p));
14059 strict_overflow_p)
14061 strict_overflow_p));
14068 strict_overflow_p);
14071 }
14073 /* We don't know sign of `t', so be conservative and return false. */
14075 }
14077 /* Return true if T is known to be non-negative. If the return
14078 value is based on the assumption that signed overflow is undefined,
14079 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14080 *STRICT_OVERFLOW_P. */
14082 bool
14084 {
14089 {
14101 strict_overflow_p)
14103 strict_overflow_p));
14107 }
14108 /* We don't know sign of `t', so be conservative and return false. */
14110 }
14112 /* Return true if T is known to be non-negative. If the return
14113 value is based on the assumption that signed overflow is undefined,
14114 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14115 *STRICT_OVERFLOW_P. */
14117 bool
14120 {
14123 {
14141 /* Always true. */
14145 /* sqrt(-0.0) is -0.0. */
14149 strict_overflow_p);
14182 /* True if the 1st argument is nonnegative. */
14184 strict_overflow_p);
14187 /* True if the 1st OR 2nd arguments are nonnegative. */
14189 strict_overflow_p)
14191 strict_overflow_p)));
14194 /* True if the 1st AND 2nd arguments are nonnegative. */
14196 strict_overflow_p)
14198 strict_overflow_p)));
14201 /* True if the 2nd argument is nonnegative. */
14203 strict_overflow_p);
14206 /* True if the 1st argument is nonnegative or the second
14207 argument is an even integer. */
14212 strict_overflow_p);
14215 /* True if the 1st argument is nonnegative or the second
14216 argument is an even integer valued real. */
14218 {
14219 REAL_VALUE_TYPE c;
14220 HOST_WIDE_INT n;
14225 {
14226 REAL_VALUE_TYPE cint;
14231 }
14232 }
14234 strict_overflow_p);
14238 }
14240 type);
14241 }
14243 /* Return true if T is known to be non-negative. If the return
14244 value is based on the assumption that signed overflow is undefined,
14245 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14246 *STRICT_OVERFLOW_P. */
14248 bool
14250 {
14256 {
14258 {
14262 /* If the initializer is non-void, then it's a normal expression
14263 that will be assigned to the slot. */
14267 /* Otherwise, the initializer sets the slot in some way. One common
14268 way is an assignment statement at the end of the initializer. */
14270 {
14278 else
14280 }
14284 strict_overflow_p);
14287 }
14290 {
14296 arg0,
14297 arg1,
14298 strict_overflow_p);
14299 }
14303 strict_overflow_p);
14306 strict_overflow_p);
14309 strict_overflow_p);
14314 }
14316 /* We don't know sign of `t', so be conservative and return false. */
14318 }
14320 /* Return true if T is known to be non-negative. If the return
14321 value is based on the assumption that signed overflow is undefined,
14322 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14323 *STRICT_OVERFLOW_P. */
14325 bool
14327 {
14334 {
14341 strict_overflow_p);
14347 strict_overflow_p);
14356 }
14359 {
14367 strict_overflow_p);
14372 strict_overflow_p);
14387 }
14388 }
14390 /* Return true if `t' is known to be non-negative. Handle warnings
14391 about undefined signed overflow. */
14393 bool
14395 {
14402 "determining that expression is always "
14404 WARN_STRICT_OVERFLOW_MISC);
14406 }
14409 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14410 For floating point we further ensure that T is not denormal.
14411 Similar logic is present in nonzero_address in rtlanal.h.
14413 If the return value is based on the assumption that signed overflow
14414 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14415 change *STRICT_OVERFLOW_P. */
14417 bool
14420 {
14422 {
14425 strict_overflow_p);
14428 {
14434 strict_overflow_p));
14435 }
14440 strict_overflow_p);
14444 }
14447 }
14449 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14450 For floating point we further ensure that T is not denormal.
14451 Similar logic is present in nonzero_address in rtlanal.h.
14453 If the return value is based on the assumption that signed overflow
14454 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14455 change *STRICT_OVERFLOW_P. */
14457 bool
14459 tree type,
14460 tree op0,
14462 {
14465 {
14469 {
14470 /* With the presence of negative values it is hard
14471 to say something. */
14478 /* One of operands must be positive and the other non-negative. */
14479 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14480 overflows, on a twos-complement machine the sum of two
14481 nonnegative numbers can never be zero. */
14483 strict_overflow_p)
14485 strict_overflow_p));
14486 }
14491 {
14493 strict_overflow_p)
14495 strict_overflow_p))
14496 {
14499 }
14500 }
14509 {
14512 }
14519 {
14523 /* When both operands are nonzero, then MAX must be too. */
14525 strict_overflow_p))
14528 /* MAX where operand 0 is positive is positive. */
14530 strict_overflow_p);
14531 }
14532 /* MAX where operand 1 is positive is positive. */
14537 {
14541 }
14546 strict_overflow_p)
14548 strict_overflow_p));
14552 }
14555 }
14557 /* Return true when T is an address and is known to be nonzero.
14558 For floating point we further ensure that T is not denormal.
14559 Similar logic is present in nonzero_address in rtlanal.h.
14561 If the return value is based on the assumption that signed overflow
14562 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14563 change *STRICT_OVERFLOW_P. */
14565 bool
14567 {
14570 {
14575 {
14581 /* Weak declarations may link to NULL. */
14585 /* Constants are never weak. */
14590 }
14598 {
14602 }
14607 }
14609 }
14611 /* Return true when T is an address and is known to be nonzero.
14612 For floating point we further ensure that T is not denormal.
14613 Similar logic is present in nonzero_address in rtlanal.h.
14615 If the return value is based on the assumption that signed overflow
14616 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14617 change *STRICT_OVERFLOW_P. */
14619 bool
14621 {
14625 /* Doing something useful for floating point would need more work. */
14631 {
14634 strict_overflow_p);
14640 strict_overflow_p);
14648 }
14651 {
14654 strict_overflow_p);
14662 strict_overflow_p);
14679 strict_overflow_p);
14683 strict_overflow_p);
14690 }
14692 }
14694 /* Return true when T is an address and is known to be nonzero.
14695 Handle warnings about undefined signed overflow. */
14697 bool
14699 {
14706 "determining that expression is always "
14708 WARN_STRICT_OVERFLOW_MISC);
14710 }
14712 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
14713 attempt to fold the expression to a constant without modifying TYPE,
14714 OP0 or OP1.
14716 If the expression could be simplified to a constant, then return
14717 the constant. If the expression would not be simplified to a
14718 constant, then return NULL_TREE. */
14720 tree
14722 {
14725 }
14727 /* Given the components of a unary expression CODE, TYPE and OP0,
14728 attempt to fold the expression to a constant without modifying
14729 TYPE or OP0.
14731 If the expression could be simplified to a constant, then return
14732 the constant. If the expression would not be simplified to a
14733 constant, then return NULL_TREE. */
14735 tree
14737 {
14740 }
14742 /* If EXP represents referencing an element in a constant string
14743 (either via pointer arithmetic or array indexing), return the
14744 tree representing the value accessed, otherwise return NULL. */
14746 tree
14748 {
14752 {
14754 tree index;
14755 tree string;
14759 else
14760 {
14764 /* Optimize the special-case of a zero lower bound.
14766 We convert the low_bound to sizetype to avoid some problems
14767 with constant folding. (E.g. suppose the lower bound is 1,
14768 and its mode is QI. Without the conversion,l (ARRAY
14769 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
14770 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
14775 }
14788 }
14790 }
14792 /* Return the tree for neg (ARG0) when ARG0 is known to be either
14793 an integer constant, real, or fixed-point constant.
14795 TYPE is the type of the result. */
14797 static tree
14799 {
14803 {
14805 {
14807 HOST_WIDE_INT high;
14815 }
14822 {
14823 FIXED_VALUE_TYPE f;
14828 /* Propagate overflow flags. */
14830 {
14833 }
14837 }
14841 }
14844 }
14846 /* Return the tree for abs (ARG0) when ARG0 is known to be either
14847 an integer constant or real constant.
14849 TYPE is the type of the result. */
14851 tree
14853 {
14857 {
14859 /* If the value is unsigned, then the absolute value is
14860 the same as the ordinary value. */
14863 /* Similarly, if the value is non-negative. */
14866 /* If the value is negative, then the absolute value is
14867 its negation. */
14868 else
14869 {
14871 HOST_WIDE_INT high;
14877 }
14883 else
14889 }
14892 }
14894 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
14895 constant. TYPE is the type of the result. */
14897 static tree
14899 {
14909 }
14911 /* Given CODE, a relational operator, the target type, TYPE and two
14912 constant operands OP0 and OP1, return the result of the
14913 relational operation. If the result is not a compile time
14914 constant, then return NULL_TREE. */
14916 static tree
14918 {
14921 /* From here on, the only cases we handle are when the result is
14922 known to be a constant. */
14925 {
14929 /* Handle the cases where either operand is a NaN. */
14931 {
14933 {
14961 }
14964 }
14967 }
14970 {
14974 }
14976 /* Handle equality/inequality of complex constants. */
14978 {
14989 else
14991 }
14993 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14995 To compute GT, swap the arguments and do LT.
14996 To compute GE, do LT and invert the result.
14997 To compute LE, swap the arguments, do LT and invert the result.
14998 To compute NE, do EQ and invert the result.
15000 Therefore, the code below must handle only EQ and LT. */
15003 {
15008 }
15010 /* Note that it is safe to invert for real values here because we
15011 have already handled the one case that it matters. */
15015 {
15018 }
15020 /* Compute a result for LT or EQ if args permit;
15021 Otherwise return T. */
15023 {
15028 else
15030 }
15031 else
15037 }
15039 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15040 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15041 itself. */
15043 tree
15045 {
15046 /* If the expression does not have side effects then we don't have to wrap
15047 it with a cleanup point expression. */
15051 /* If the expression is a return, check to see if the expression inside the
15052 return has no side effects or the right hand side of the modify expression
15053 inside the return. If either don't have side effects set we don't need to
15054 wrap the expression in a cleanup point expression. Note we don't check the
15055 left hand side of the modify because it should always be a return decl. */
15057 {
15064 }
15067 }
15069 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15070 of an indirection through OP0, or NULL_TREE if no simplification is
15071 possible. */
15073 tree
15075 {
15077 tree subtype;
15085 {
15088 /* *&CONST_DECL -> to the value of the const decl. */
15091 /* *&p => p; make sure to handle *&"str"[cst] here. */
15093 {
15097 else
15099 }
15100 /* *(foo *)&fooarray => fooarray[0] */
15103 {
15109 }
15110 /* *(foo *)&complexfoo => __real__ complexfoo */
15114 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15117 {
15121 }
15122 }
15124 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15127 {
15130 tree op00type;
15137 {
15148 }
15149 }
15152 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15155 {
15158 tree op00type;
15165 {
15169 }
15170 }
15172 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15175 {
15176 tree type_domain;
15183 }
15186 }
15188 /* Builds an expression for an indirection through T, simplifying some
15189 cases. */
15191 tree
15193 {
15199 else
15201 }
15203 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15205 tree
15207 {
15212 else
15214 }
15216 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15217 whose result is ignored. The type of the returned tree need not be
15218 the same as the original expression. */
15220 tree
15222 {
15228 {
15239 else
15245 {
15261 }
15266 }
15267 }
15269 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15270 This can only be applied to objects of a sizetype. */
15272 tree
15274 {
15281 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15282 have to do anything. Only do this when we are not given a const,
15283 because in that case, this check is more expensive than just
15284 doing it. */
15286 {
15291 }
15293 /* If divisor is a power of two, simplify this to bit manipulation. */
15295 {
15297 {
15310 {
15311 high++;
15314 }
15318 }
15319 else
15320 {
15321 tree t;
15327 }
15328 }
15329 else
15330 {
15335 }
15338 }
15340 /* Likewise, but round down. */
15342 tree
15344 {
15351 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15352 have to do anything. Only do this when we are not given a const,
15353 because in that case, this check is more expensive than just
15354 doing it. */
15356 {
15361 }
15363 /* If divisor is a power of two, simplify this to bit manipulation. */
15365 {
15366 tree t;
15370 }
15371 else
15372 {
15377 }
15380 }
15382 /* Returns the pointer to the base of the object addressed by EXP and
15383 extracts the information about the offset of the access, storing it
15384 to PBITPOS and POFFSET. */
15386 static tree
15389 {
15390 tree core;
15393 HOST_WIDE_INT bitsize;
15396 {
15401 }
15402 else
15403 {
15407 }
15410 }
15412 /* Returns true if addresses of E1 and E2 differ by a constant, false
15413 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15415 bool
15417 {
15431 {
15441 }
15443 {
15444 /* If only one of the offsets is non-constant, the difference cannot
15445 be a constant. */
15447 }
15448 else
15453 }
15455 /* Simplify the floating point expression EXP when the sign of the
15456 result is not significant. Return NULL_TREE if no simplification
15457 is possible. */
15459 tree
15461 {
15465 {
15500 {
15503 {
15505 /* Strip copysign function call, return the 1st argument. */
15511 /* Strip sign ops from the argument of "odd" math functions. */
15513 {
15517 }
15519 }
15520 }
15525 }
15527 }