| blob | 67c52b4a836905851bc5ac087ecb5c912f1363d8 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide, size_binop
31 and force_fit_type_double.
33 fold takes a tree as argument and returns a simplified tree.
35 size_binop takes a tree code for an arithmetic operation
36 and two operands that are trees, and produces a tree for the
37 result, assuming the type comes from `sizetype'.
39 size_int takes an integer value, and creates a tree constant
40 with type from `sizetype'.
42 force_fit_type_double takes a constant, an overflowable flag and a
43 prior overflow indicator. It forces the value to fit the type and
44 sets TREE_OVERFLOW.
46 Note: Since the folders get called on non-gimple code as well as
47 gimple code, we need to handle GIMPLE tuples as well as their
48 corresponding tree equivalents. */
70 /* Nonzero if we are folding constants inside an initializer; zero
71 otherwise. */
74 /* The following constants represent a bit based encoding of GCC's
75 comparison operators. This encoding simplifies transformations
76 on relational comparison operators, such as AND and OR. */
94 };
127 tree);
148 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
149 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
150 and SUM1. Then this yields nonzero if overflow occurred during the
151 addition.
153 Overflow occurs if A and B have the same sign, but A and SUM differ in
154 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
155 sign. */
156 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
157 \f
158 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
159 We do that by representing the two-word integer in 4 words, with only
160 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
161 number. The value of the word is LOWPART + HIGHPART * BASE. */
163 #define LOWPART(x) \
164 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
165 #define HIGHPART(x) \
166 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
167 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
169 /* Unpack a two-word integer into 4 words.
170 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
171 WORDS points to the array of HOST_WIDE_INTs. */
173 static void
175 {
180 }
182 /* Pack an array of 4 words into a two-word integer.
183 WORDS points to the array of words.
184 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
186 static void
189 {
192 }
193 \f
194 /* Force the double-word integer L1, H1 to be within the range of the
195 integer type TYPE. Stores the properly truncated and sign-extended
196 double-word integer in *LV, *HV. Returns true if the operation
197 overflows, that is, argument and result are different. */
199 int
202 {
211 else
214 /* Size types *are* sign extended. */
219 /* First clear all bits that are beyond the type's precision. */
221 ;
224 else
225 {
229 }
231 /* Then do sign extension if necessary. */
237 {
238 /* Sign extend top half? */
242 }
244 {
247 }
248 else
249 {
250 /* Sign extend bottom half? */
252 {
255 }
256 }
261 /* If the value didn't fit, signal overflow. */
263 }
265 /* We force the double-int HIGH:LOW to the range of the type TYPE by
266 sign or zero extending it.
267 OVERFLOWABLE indicates if we are interested
268 in overflow of the value, when >0 we are only interested in signed
269 overflow, for <0 we are interested in any overflow. OVERFLOWED
270 indicates whether overflow has already occurred. CONST_OVERFLOWED
271 indicates whether constant overflow has already occurred. We force
272 T's value to be within range of T's type (by setting to 0 or 1 all
273 the bits outside the type's range). We set TREE_OVERFLOWED if,
274 OVERFLOWED is nonzero,
275 or OVERFLOWABLE is >0 and signed overflow occurs
276 or OVERFLOWABLE is <0 and any overflow occurs
277 We return a new tree node for the extended double-int. The node
278 is shared if no overflow flags are set. */
280 tree
284 {
288 /* Size types *are* sign extended. */
295 /* If we need to set overflow flags, return a new unshared node. */
297 {
301 {
308 }
309 }
311 /* Else build a shared node. */
313 }
314 \f
315 /* Add two doubleword integers with doubleword result.
316 Return nonzero if the operation overflows according to UNSIGNED_P.
317 Each argument is given as two `HOST_WIDE_INT' pieces.
318 One argument is L1 and H1; the other, L2 and H2.
319 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
321 int
326 {
328 HOST_WIDE_INT h;
338 else
340 }
342 /* Negate a doubleword integer with doubleword result.
343 Return nonzero if the operation overflows, assuming it's signed.
344 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
345 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
347 int
350 {
352 {
356 }
357 else
358 {
362 }
363 }
364 \f
365 /* Multiply two doubleword integers with doubleword result.
366 Return nonzero if the operation overflows according to UNSIGNED_P.
367 Each argument is given as two `HOST_WIDE_INT' pieces.
368 One argument is L1 and H1; the other, L2 and H2.
369 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
371 int
376 {
391 {
394 {
396 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
398 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
402 }
404 }
409 /* Unsigned overflow is immediate. */
413 /* Check for signed overflow by calculating the signed representation of the
414 top half of the result; it should agree with the low half's sign bit. */
416 {
419 }
421 {
424 }
426 }
427 \f
428 /* Shift the doubleword integer in L1, H1 left by COUNT places
429 keeping only PREC bits of result.
430 Shift right if COUNT is negative.
431 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
432 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
434 void
438 {
442 {
445 }
451 {
452 /* Shifting by the host word size is undefined according to the
453 ANSI standard, so we must handle this as a special case. */
456 }
458 {
461 }
462 else
463 {
467 }
469 /* Sign extend all bits that are beyond the precision. */
477 ;
479 {
482 }
483 else
484 {
488 }
489 }
491 /* Shift the doubleword integer in L1, H1 right by COUNT places
492 keeping only PREC bits of result. COUNT must be positive.
493 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
494 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
496 void
501 {
504 signmask = (arith
512 {
513 /* Shifting by the host word size is undefined according to the
514 ANSI standard, so we must handle this as a special case. */
517 }
519 {
522 }
523 else
524 {
528 }
530 /* Zero / sign extend all bits that are beyond the precision. */
533 {
536 }
538 ;
540 {
543 }
544 else
545 {
549 }
550 }
551 \f
552 /* Rotate the doubleword integer in L1, H1 left by COUNT places
553 keeping only PREC bits of result.
554 Rotate right if COUNT is negative.
555 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
557 void
561 {
573 }
575 /* Rotate the doubleword integer in L1, H1 left by COUNT places
576 keeping only PREC bits of result. COUNT must be positive.
577 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
579 void
583 {
595 }
596 \f
597 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
598 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
599 CODE is a tree code for a kind of division, one of
600 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
601 or EXACT_DIV_EXPR
602 It controls how the quotient is rounded to an integer.
603 Return nonzero if the operation overflows.
604 UNS nonzero says do unsigned division. */
606 int
609 HOST_WIDE_INT hnum_orig,
611 HOST_WIDE_INT hden_orig,
615 {
631 /* Calculate quotient sign and convert operands to unsigned. */
633 {
635 {
637 /* (minimum integer) / (-1) is the only overflow case. */
641 }
643 {
646 }
647 }
652 /* This unsigned division rounds toward zero. */
655 }
659 /* hden != 0 already checked. */
664 }
674 /* Special code for when the divisor < BASE. */
676 {
677 /* hnum != 0 already checked. */
679 {
683 }
684 }
685 else
686 {
687 /* Full double precision division,
688 with thanks to Don Knuth's "Seminumerical Algorithms". */
692 /* Find the highest nonzero divisor digit. */
695 {
698 }
700 /* Insure that the first digit of the divisor is at least BASE/2.
701 This is required by the quotient digit estimation algorithm. */
708 {
712 }
717 {
722 }
723 }
727 /* Main loop */
729 {
730 /* Guess the next quotient digit, quo_est, by dividing the first
731 two remaining dividend digits by the high order quotient digit.
732 quo_est is never low and is at most 2 high. */
739 else
742 /* Refine quo_est so it's usually correct, and at most one high. */
747 quo_est--;
749 /* Try QUO_EST as the quotient digit, by multiplying the
750 divisor by QUO_EST and subtracting from the remaining dividend.
751 Keep in mind that QUO_EST is the I - 1st digit. */
755 {
761 }
763 /* If quo_est was high by one, then num[i] went negative and
764 we need to correct things. */
766 {
767 quo_est--;
770 {
774 }
777 }
779 /* Store the quotient digit. */
781 }
782 }
786 finish_up:
787 /* If result is negative, make it so. */
791 /* Compute trial remainder: rem = num - (quo * den) */
797 {
806 {
807 /* quo = quo - 1; */
810 }
811 else
818 {
821 }
822 else
828 {
834 /* Get absolute values. */
840 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
849 {
851 /* quo = quo - 1; */
854 else
855 /* quo = quo + 1; */
858 }
859 else
861 }
866 }
868 /* Compute true remainder: rem = num - (quo * den) */
873 }
875 /* If ARG2 divides ARG1 with zero remainder, carries out the division
876 of type CODE and returns the quotient.
877 Otherwise returns NULL_TREE. */
879 static tree
881 {
891 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
892 &obj[some_exotic_number]. */
894 {
898 type);
899 }
900 else
911 }
912 \f
913 /* This is nonzero if we should defer warnings about undefined
914 overflow. This facility exists because these warnings are a
915 special case. The code to estimate loop iterations does not want
916 to issue any warnings, since it works with expressions which do not
917 occur in user code. Various bits of cleanup code call fold(), but
918 only use the result if it has certain characteristics (e.g., is a
919 constant); that code only wants to issue a warning if the result is
920 used. */
924 /* If a warning about undefined overflow is deferred, this is the
925 warning. Note that this may cause us to turn two warnings into
926 one, but that is fine since it is sufficient to only give one
927 warning per expression. */
931 /* If a warning about undefined overflow is deferred, this is the
932 level at which the warning should be emitted. */
936 /* Start deferring overflow warnings. We could use a stack here to
937 permit nested calls, but at present it is not necessary. */
939 void
941 {
943 }
945 /* Stop deferring overflow warnings. If there is a pending warning,
946 and ISSUE is true, then issue the warning if appropriate. STMT is
947 the statement with which the warning should be associated (used for
948 location information); STMT may be NULL. CODE is the level of the
949 warning--a warn_strict_overflow_code value. This function will use
950 the smaller of CODE and the deferred code when deciding whether to
951 issue the warning. CODE may be zero to mean to always use the
952 deferred code. */
954 void
956 {
958 location_t locus;
963 {
969 }
980 /* Use the smallest code level when deciding to issue the
981 warning. */
990 else
993 }
995 /* Stop deferring overflow warnings, ignoring any deferred
996 warnings. */
998 void
1000 {
1002 }
1004 /* Whether we are deferring overflow warnings. */
1006 bool
1008 {
1010 }
1012 /* This is called when we fold something based on the fact that signed
1013 overflow is undefined. */
1015 static void
1017 {
1019 {
1022 {
1025 }
1026 }
1029 }
1030 \f
1031 /* Return true if the built-in mathematical function specified by CODE
1032 is odd, i.e. -f(x) == f(-x). */
1034 static bool
1036 {
1038 {
1072 }
1074 }
1076 /* Check whether we may negate an integer constant T without causing
1077 overflow. */
1079 bool
1081 {
1084 tree type;
1094 {
1099 }
1100 else
1105 }
1107 /* Determine whether an expression T can be cheaply negated using
1108 the function negate_expr without introducing undefined overflow. */
1110 static bool
1112 {
1113 tree type;
1122 {
1127 /* Check that -CST will not overflow type. */
1153 /* -(A + B) -> (-B) - A. */
1158 /* -(A + B) -> (-A) - B. */
1162 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1172 /* Fall through. */
1185 /* In general we can't negate A / B, because if A is INT_MIN and
1186 B is 1, we may turn this into INT_MIN / -1 which is undefined
1187 and actually traps on some architectures. But if overflow is
1188 undefined, we can negate, because - (INT_MIN / 1) is an
1189 overflow. */
1197 /* Negate -((double)float) as (double)(-float). */
1199 {
1203 }
1207 /* Negate -f(x) as f(-x). */
1213 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1215 {
1221 }
1226 }
1228 }
1230 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1231 simplification is possible.
1232 If negate_expr_p would return true for T, NULL_TREE will never be
1233 returned. */
1235 static tree
1237 {
1239 tree tem;
1242 {
1243 /* Convert - (~A) to A + 1. */
1259 /* Two's complement FP formats, such as c4x, may overflow. */
1269 {
1278 }
1300 {
1301 /* -(A + B) -> (-B) - A. */
1305 {
1309 }
1311 /* -(A + B) -> (-A) - B. */
1313 {
1317 }
1318 }
1322 /* - (A - B) -> B - A */
1334 /* Fall through. */
1338 {
1347 }
1355 /* In general we can't negate A / B, because if A is INT_MIN and
1356 B is 1, we may turn this into INT_MIN / -1 which is undefined
1357 and actually traps on some architectures. But if overflow is
1358 undefined, we can negate, because - (INT_MIN / 1) is an
1359 overflow. */
1361 {
1366 {
1373 }
1376 {
1383 }
1384 }
1388 /* Convert -((double)float) into (double)(-float). */
1390 {
1394 }
1398 /* Negate -f(x) as f(-x). */
1401 {
1407 }
1411 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1413 {
1418 {
1425 }
1426 }
1431 }
1434 }
1436 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1437 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1438 return NULL_TREE. */
1440 static tree
1442 {
1455 }
1456 \f
1457 /* Split a tree IN into a constant, literal and variable parts that could be
1458 combined with CODE to make IN. "constant" means an expression with
1459 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1460 commutative arithmetic operation. Store the constant part into *CONP,
1461 the literal in *LITP and return the variable part. If a part isn't
1462 present, set it to null. If the tree does not decompose in this way,
1463 return the entire tree as the variable part and the other parts as null.
1465 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1466 case, we negate an operand that was subtracted. Except if it is a
1467 literal for which we use *MINUS_LITP instead.
1469 If NEGATE_P is true, we are negating all of IN, again except a literal
1470 for which we use *MINUS_LITP instead.
1472 If IN is itself a literal or constant, return it as appropriate.
1474 Note that we do not guarantee that any of the three values will be the
1475 same type as IN, but they will have the same signedness and mode. */
1477 static tree
1480 {
1487 /* Strip any conversions that don't change the machine mode or signedness. */
1496 /* We can associate addition and subtraction together (even
1497 though the C standard doesn't say so) for integers because
1498 the value is not affected. For reals, the value might be
1499 affected, so we can't. */
1502 {
1508 /* First see if either of the operands is a literal, then a constant. */
1521 /* If we haven't dealt with either operand, this is not a case we can
1522 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1527 else
1530 /* Now do any needed negations. */
1537 }
1540 else
1544 {
1551 }
1554 }
1556 /* Re-associate trees split by the above function. T1 and T2 are either
1557 expressions to associate or null. Return the new expression, if any. If
1558 we build an operation, do it in TYPE and with CODE. */
1560 static tree
1562 {
1568 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1569 try to fold this since we will have infinite recursion. But do
1570 deal with any NEGATE_EXPRs. */
1573 {
1575 {
1584 }
1586 {
1589 }
1593 }
1597 }
1598 \f
1599 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1600 for use in int_const_binop, size_binop and size_diffop. */
1602 static bool
1604 {
1611 {
1620 }
1625 }
1628 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1629 to produce a new constant. Return NULL_TREE if we don't know how
1630 to evaluate CODE at compile-time.
1632 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1634 tree
1636 {
1640 HOST_WIDE_INT hi;
1642 HOST_WIDE_INT garbageh;
1643 tree t;
1646 int is_sizetype
1656 {
1672 /* It's unclear from the C standard whether shifts can overflow.
1673 The following code ignores overflow; perhaps a C standard
1674 interpretation ruling is needed. */
1703 /* This is a shortcut for a common special case. */
1708 {
1714 }
1716 /* ... fall through ... */
1722 {
1725 }
1728 {
1731 }
1738 /* This is a shortcut for a common special case. */
1743 {
1748 }
1750 /* ... fall through ... */
1768 else
1774 else
1780 }
1783 {
1786 /* Propagate overflow flags ourselves. */
1789 {
1792 }
1793 }
1794 else
1800 }
1802 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1803 constant. We assume ARG1 and ARG2 have the same data type, or at least
1804 are the same kind of constant and the same machine mode. Return zero if
1805 combining the constants is not allowed in the current operating mode.
1807 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1809 static tree
1811 {
1812 /* Sanity check for the recursive cases. */
1823 {
1825 REAL_VALUE_TYPE d1;
1826 REAL_VALUE_TYPE d2;
1827 REAL_VALUE_TYPE value;
1828 REAL_VALUE_TYPE result;
1832 /* The following codes are handled by real_arithmetic. */
1834 {
1845 }
1853 /* Don't perform operation if we honor signaling NaNs and
1854 either operand is a NaN. */
1859 /* Don't perform operation if it would raise a division
1860 by zero exception. */
1866 /* If either operand is a NaN, just return it. Otherwise, set up
1867 for floating-point trap; we return an overflow. */
1876 /* Don't constant fold this floating point operation if
1877 the result has overflowed and flag_trapping_math. */
1885 /* Don't constant fold this floating point operation if the
1886 result may dependent upon the run-time rounding mode and
1887 flag_rounding_math is set, or if GCC's software emulation
1888 is unable to accurately represent the result. */
1898 }
1901 {
1902 FIXED_VALUE_TYPE f1;
1903 FIXED_VALUE_TYPE f2;
1904 FIXED_VALUE_TYPE result;
1909 /* The following codes are handled by fixed_arithmetic. */
1911 {
1928 }
1935 /* Propagate overflow flags. */
1937 {
1940 }
1944 }
1947 {
1956 {
1967 notrunc);
1971 notrunc);
1975 {
1976 tree magsquared
1980 notrunc);
1981 tree t1
1985 notrunc);
1986 tree t2
1990 notrunc);
1997 }
2002 }
2006 }
2009 }
2011 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2012 indicates which particular sizetype to create. */
2014 tree
2016 {
2018 }
2019 \f
2020 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2021 is a tree code. The type of the result is taken from the operands.
2022 Both must be equivalent integer types, ala int_binop_types_match_p.
2023 If the operands are constant, so is the result. */
2025 tree
2027 {
2036 /* Handle the special case of two integer constants faster. */
2038 {
2039 /* And some specific cases even faster than that. */
2041 {
2046 }
2048 {
2051 }
2053 {
2056 }
2058 /* Handle general case of two integer constants. */
2060 }
2063 }
2065 /* Given two values, either both of sizetype or both of bitsizetype,
2066 compute the difference between the two values. Return the value
2067 in signed type corresponding to the type of the operands. */
2069 tree
2071 {
2073 tree ctype;
2078 /* If the type is already signed, just do the simple thing. */
2086 else
2089 /* If either operand is not a constant, do the conversions to the signed
2090 type and subtract. The hardware will do the right thing with any
2091 overflow in the subtraction. */
2096 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2097 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2098 overflow) and negate (which can't either). Special-case a result
2099 of zero while we're here. */
2104 else
2108 }
2109 \f
2110 /* A subroutine of fold_convert_const handling conversions of an
2111 INTEGER_CST to another integer type. */
2113 static tree
2115 {
2116 tree t;
2118 /* Given an integer constant, make new constant with new type,
2119 appropriately sign-extended or truncated. */
2122 /* Don't set the overflow when
2123 converting from a pointer, */
2125 /* or to a sizetype with same signedness
2126 and the precision is unchanged.
2127 ??? sizetype is always sign-extended,
2128 but its signedness depends on the
2129 frontend. Thus we see spurious overflows
2130 here if we do not check this. */
2145 }
2147 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2148 to an integer type. */
2150 static tree
2152 {
2154 tree t;
2156 /* The following code implements the floating point to integer
2157 conversion rules required by the Java Language Specification,
2158 that IEEE NaNs are mapped to zero and values that overflow
2159 the target precision saturate, i.e. values greater than
2160 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2161 are mapped to INT_MIN. These semantics are allowed by the
2162 C and C++ standards that simply state that the behavior of
2163 FP-to-integer conversion is unspecified upon overflow. */
2166 REAL_VALUE_TYPE r;
2170 {
2177 }
2179 /* If R is NaN, return zero and show we have an overflow. */
2181 {
2185 }
2187 /* See if R is less than the lower bound or greater than the
2188 upper bound. */
2191 {
2195 {
2199 }
2200 }
2203 {
2206 {
2209 {
2213 }
2214 }
2215 }
2223 }
2225 /* A subroutine of fold_convert_const handling conversions of a
2226 FIXED_CST to an integer type. */
2228 static tree
2230 {
2231 tree t;
2235 /* Right shift FIXED_CST to temp by fbit. */
2239 {
2244 /* Left shift temp to temp_trunc by fbit. */
2249 }
2250 else
2251 {
2256 }
2258 /* If FIXED_CST is negative, we need to round the value toward 0.
2259 By checking if the fractional bits are not zero to add 1 to temp. */
2262 {
2263 double_int one;
2267 }
2269 /* Given a fixed-point constant, make new constant with new type,
2270 appropriately sign-extended or truncated. */
2278 }
2280 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2281 to another floating point type. */
2283 static tree
2285 {
2286 REAL_VALUE_TYPE value;
2287 tree t;
2294 }
2296 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2297 to a floating point type. */
2299 static tree
2301 {
2302 REAL_VALUE_TYPE value;
2303 tree t;
2312 }
2314 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2315 to another fixed-point type. */
2317 static tree
2319 {
2320 FIXED_VALUE_TYPE value;
2321 tree t;
2328 /* Propagate overflow flags. */
2330 {
2333 }
2337 }
2339 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2340 to a fixed-point type. */
2342 static tree
2344 {
2345 FIXED_VALUE_TYPE value;
2346 tree t;
2355 /* Propagate overflow flags. */
2357 {
2360 }
2364 }
2366 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2367 to a fixed-point type. */
2369 static tree
2371 {
2372 FIXED_VALUE_TYPE value;
2373 tree t;
2381 /* Propagate overflow flags. */
2383 {
2386 }
2390 }
2392 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2393 type TYPE. If no simplification can be done return NULL_TREE. */
2395 static tree
2397 {
2403 {
2410 }
2412 {
2419 }
2421 {
2428 }
2430 }
2432 /* Construct a vector of zero elements of vector type TYPE. */
2434 static tree
2436 {
2447 }
2449 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2451 bool
2453 {
2468 {
2487 }
2488 }
2490 /* Convert expression ARG to type TYPE. Used by the middle-end for
2491 simple conversions in preference to calling the front-end's convert. */
2493 tree
2495 {
2497 tree tem;
2511 {
2516 {
2520 }
2525 {
2528 }
2535 {
2539 }
2541 {
2545 }
2547 {
2551 }
2554 {
2572 }
2577 {
2581 }
2584 {
2598 }
2602 {
2611 integer_zero_node));
2613 {
2617 {
2621 }
2629 }
2633 }
2651 }
2652 }
2653 \f
2654 /* Return false if expr can be assumed not to be an lvalue, true
2655 otherwise. */
2657 static bool
2659 {
2660 /* We only need to wrap lvalue tree codes. */
2662 {
2696 /* Assume the worst for front-end tree codes. */
2700 }
2703 }
2705 /* Return an expr equal to X but certainly not valid as an lvalue. */
2707 tree
2709 {
2710 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2711 us. */
2718 }
2720 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2721 Zero means allow extended lvalues. */
2725 /* When pedantic, return an expr equal to X but certainly not valid as a
2726 pedantic lvalue. Otherwise, return X. */
2728 static tree
2730 {
2733 else
2735 }
2736 \f
2737 /* Given a tree comparison code, return the code that is the logical inverse
2738 of the given code. It is not safe to do this for floating-point
2739 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2740 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2742 enum tree_code
2744 {
2749 {
2780 }
2781 }
2783 /* Similar, but return the comparison that results if the operands are
2784 swapped. This is safe for floating-point. */
2786 enum tree_code
2788 {
2790 {
2816 }
2817 }
2820 /* Convert a comparison tree code from an enum tree_code representation
2821 into a compcode bit-based encoding. This function is the inverse of
2822 compcode_to_comparison. */
2824 static enum comparison_code
2826 {
2828 {
2859 }
2860 }
2862 /* Convert a compcode bit-based encoding of a comparison operator back
2863 to GCC's enum tree_code representation. This function is the
2864 inverse of comparison_to_compcode. */
2866 static enum tree_code
2868 {
2870 {
2901 }
2902 }
2904 /* Return a tree for the comparison which is the combination of
2905 doing the AND or OR (depending on CODE) of the two operations LCODE
2906 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2907 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2908 if this makes the transformation invalid. */
2910 tree
2914 {
2921 {
2932 }
2935 {
2936 /* Eliminate unordered comparisons, as well as LTGT and ORD
2937 which are not used unless the mode has NaNs. */
2943 }
2945 {
2946 /* Check that the original operation and the optimized ones will trap
2947 under the same condition. */
2958 /* In a short-circuited boolean expression the LHS might be
2959 such that the RHS, if evaluated, will never trap. For
2960 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2961 if neither x nor y is NaN. (This is a mixed blessing: for
2962 example, the expression above will never trap, hence
2963 optimizing it to x < y would be invalid). */
2968 /* If the comparison was short-circuited, and only the RHS
2969 trapped, we may now generate a spurious trap. */
2974 /* If we changed the conditions that cause a trap, we lose. */
2977 }
2983 else
2986 }
2987 \f
2988 /* Return nonzero if two operands (typically of the same tree node)
2989 are necessarily equal. If either argument has side-effects this
2990 function returns zero. FLAGS modifies behavior as follows:
2992 If OEP_ONLY_CONST is set, only return nonzero for constants.
2993 This function tests whether the operands are indistinguishable;
2994 it does not test whether they are equal using C's == operation.
2995 The distinction is important for IEEE floating point, because
2996 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2997 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2999 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3000 even though it may hold multiple values during a function.
3001 This is because a GCC tree node guarantees that nothing else is
3002 executed between the evaluation of its "operands" (which may often
3003 be evaluated in arbitrary order). Hence if the operands themselves
3004 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3005 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3006 unset means assuming isochronic (or instantaneous) tree equivalence.
3007 Unless comparing arbitrary expression trees, such as from different
3008 statements, this flag can usually be left unset.
3010 If OEP_PURE_SAME is set, then pure functions with identical arguments
3011 are considered the same. It is used when the caller has other ways
3012 to ensure that global memory is unchanged in between. */
3014 int
3016 {
3017 /* If either is ERROR_MARK, they aren't equal. */
3021 /* Check equality of integer constants before bailing out due to
3022 precision differences. */
3026 /* If both types don't have the same signedness, then we can't consider
3027 them equal. We must check this before the STRIP_NOPS calls
3028 because they may change the signedness of the arguments. As pointers
3029 strictly don't have a signedness, require either two pointers or
3030 two non-pointers as well. */
3035 /* If both types don't have the same precision, then it is not safe
3036 to strip NOPs. */
3043 /* In case both args are comparisons but with different comparison
3044 code, try to swap the comparison operands of one arg to produce
3045 a match and compare that variant. */
3049 {
3057 }
3060 /* This is needed for conversions and for COMPONENT_REF.
3061 Might as well play it safe and always test this. */
3067 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3068 We don't care about side effects in that case because the SAVE_EXPR
3069 takes care of that for us. In all other cases, two expressions are
3070 equal if they have no side effects. If we have two identical
3071 expressions with side effects that should be treated the same due
3072 to the only side effects being identical SAVE_EXPR's, that will
3073 be detected in the recursive calls below. */
3079 /* Next handle constant cases, those for which we can return 1 even
3080 if ONLY_CONST is set. */
3083 {
3098 {
3099 /* If we do not distinguish between signed and unsigned zero,
3100 consider them equal. */
3103 }
3107 {
3113 {
3115 flags))
3119 }
3122 }
3126 flags)
3128 flags));
3141 }
3146 /* Define macros to test an operand from arg0 and arg1 for equality and a
3147 variant that allows null and views null as being different from any
3148 non-null value. In the latter case, if either is null, the both
3149 must be; otherwise, do the normal comparison. */
3150 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3151 TREE_OPERAND (arg1, N), flags)
3153 #define OP_SAME_WITH_NULL(N) \
3154 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3155 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3158 {
3160 /* Two conversions are equal only if signedness and modes match. */
3162 {
3163 CASE_CONVERT:
3171 }
3181 /* For commutative ops, allow the other order. */
3189 /* If either of the pointer (or reference) expressions we are
3190 dereferencing contain a side effect, these cannot be equal. */
3196 {
3206 /* Operands 2 and 3 may be null.
3207 Compare the array index by value if it is constant first as we
3208 may have different types but same value here. */
3217 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3218 may be NULL when we're called to compare MEM_EXPRs. */
3228 }
3232 {
3247 /* Otherwise take into account this is a commutative operation. */
3258 }
3262 {
3264 /* If the CALL_EXPRs call different functions, then they
3265 clearly can not be equal. */
3267 flags))
3270 {
3274 else
3278 }
3280 /* Now see if all the arguments are the same. */
3281 {
3292 /* If we get here and both argument lists are exhausted
3293 then the CALL_EXPRs are equal. */
3295 }
3298 }
3301 /* Consider __builtin_sqrt equal to sqrt. */
3309 }
3311 #undef OP_SAME
3312 #undef OP_SAME_WITH_NULL
3313 }
3314 \f
3315 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3316 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3318 When in doubt, return 0. */
3320 static int
3322 {
3334 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3335 and see if the inner values are the same. This removes any
3336 signedness comparison, which doesn't matter here. */
3343 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3344 actual comparison operand, ARG0.
3346 First throw away any conversions to wider types
3347 already present in the operands. */
3356 {
3359 /* Make sure shorter operand is extended the right way
3360 to match the longer operand. */
3366 }
3369 }
3370 \f
3371 /* See if ARG is an expression that is either a comparison or is performing
3372 arithmetic on comparisons. The comparisons must only be comparing
3373 two different values, which will be stored in *CVAL1 and *CVAL2; if
3374 they are nonzero it means that some operands have already been found.
3375 No variables may be used anywhere else in the expression except in the
3376 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3377 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3379 If this is true, return 1. Otherwise, return zero. */
3381 static int
3383 {
3387 /* We can handle some of the tcc_expression cases here. */
3397 {
3398 /* If we've already found a CVAL1 or CVAL2, this expression is
3399 two complex to handle. */
3405 }
3408 {
3431 /* First see if we can handle the first operand, then the second. For
3432 the second operand, we know *CVAL1 can't be zero. It must be that
3433 one side of the comparison is each of the values; test for the
3434 case where this isn't true by failing if the two operands
3435 are the same. */
3444 ;
3448 ;
3449 else
3453 ;
3457 ;
3458 else
3465 }
3466 }
3467 \f
3468 /* ARG is a tree that is known to contain just arithmetic operations and
3469 comparisons. Evaluate the operations in the tree substituting NEW0 for
3470 any occurrence of OLD0 as an operand of a comparison and likewise for
3471 NEW1 and OLD1. */
3473 static tree
3475 {
3480 /* We can handle some of the tcc_expression cases here. */
3488 {
3503 {
3520 }
3521 /* Fall through - ??? */
3524 {
3528 /* We need to check both for exact equality and tree equality. The
3529 former will be true if the operand has a side-effect. In that
3530 case, we know the operand occurred exactly once. */
3543 }
3547 }
3548 }
3549 \f
3550 /* Return a tree for the case when the result of an expression is RESULT
3551 converted to TYPE and OMITTED was previously an operand of the expression
3552 but is now not needed (e.g., we folded OMITTED * 0).
3554 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3555 the conversion of RESULT to TYPE. */
3557 tree
3559 {
3562 /* If the resulting operand is an empty statement, just return the omitted
3563 statement casted to void. */
3571 }
3573 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3575 static tree
3577 {
3580 /* If the resulting operand is an empty statement, just return the omitted
3581 statement casted to void. */
3589 }
3591 /* Return a tree for the case when the result of an expression is RESULT
3592 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3593 of the expression but are now not needed.
3595 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3596 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3597 evaluated before OMITTED2. Otherwise, if neither has side effects,
3598 just do the conversion of RESULT to TYPE. */
3600 tree
3602 {
3611 }
3613 \f
3614 /* Return a simplified tree node for the truth-negation of ARG. This
3615 never alters ARG itself. We assume that ARG is an operation that
3616 returns a truth value (0 or 1).
3618 FIXME: one would think we would fold the result, but it causes
3619 problems with the dominator optimizer. */
3621 tree
3623 {
3627 /* If this is a comparison, we can simply invert it, except for
3628 floating-point non-equality comparisons, in which case we just
3629 enclose a TRUTH_NOT_EXPR around what we have. */
3632 {
3635 && flag_trapping_math
3639 else
3640 {
3645 else
3648 }
3649 }
3652 {
3667 /* Here we can invert either operand. We invert the first operand
3668 unless the second operand is a TRUTH_NOT_EXPR in which case our
3669 result is the XOR of the first operand with the inside of the
3670 negation of the second operand. */
3675 else
3694 {
3697 /* A COND_EXPR may have a throw as one operand, which
3698 then has void type. Just leave void operands
3699 as they are. */
3705 }
3738 }
3741 }
3743 /* Return a simplified tree node for the truth-negation of ARG. This
3744 never alters ARG itself. We assume that ARG is an operation that
3745 returns a truth value (0 or 1).
3747 FIXME: one would think we would fold the result, but it causes
3748 problems with the dominator optimizer. */
3750 tree
3752 {
3753 tree tem;
3763 }
3765 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3766 operands are another bit-wise operation with a common input. If so,
3767 distribute the bit operations to save an operation and possibly two if
3768 constants are involved. For example, convert
3769 (A | B) & (A | C) into A | (B & C)
3770 Further simplification will occur if B and C are constants.
3772 If this optimization cannot be done, 0 will be returned. */
3774 static tree
3776 {
3777 tree common;
3787 {
3791 }
3793 {
3797 }
3799 {
3803 }
3805 {
3809 }
3810 else
3818 }
3820 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3821 with code CODE. This optimization is unsafe. */
3822 static tree
3824 {
3828 /* (A / C) +- (B / C) -> (A +- B) / C. */
3838 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3843 {
3855 }
3858 }
3859 \f
3860 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3861 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3863 static tree
3866 {
3870 {
3877 }
3891 }
3893 /* Optimize a bit-field compare.
3895 There are two cases: First is a compare against a constant and the
3896 second is a comparison of two items where the fields are at the same
3897 bit position relative to the start of a chunk (byte, halfword, word)
3898 large enough to contain it. In these cases we can avoid the shift
3899 implicit in bitfield extractions.
3901 For constants, we emit a compare of the shifted constant with the
3902 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3903 compared. For two fields at the same position, we do the ANDs with the
3904 similar mask and compare the result of the ANDs.
3906 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3907 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3908 are the left and right operands of the comparison, respectively.
3910 If the optimization described above can be done, we return the resulting
3911 tree. Otherwise we return zero. */
3913 static tree
3916 {
3925 tree mask;
3926 tree offset;
3928 /* Get all the information about the extractions being done. If the bit size
3929 if the same as the size of the underlying object, we aren't doing an
3930 extraction at all and so can do nothing. We also don't want to
3931 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3932 then will no longer be able to replace it. */
3940 {
3941 /* If this is not a constant, we can only do something if bit positions,
3942 sizes, and signedness are the same. */
3950 }
3952 /* See if we can find a mode to refer to this field. We should be able to,
3953 but fail if we can't. */
3962 /* Set signed and unsigned types of the precision of this mode for the
3963 shifts below. */
3967 /* Compute the bit position and size for the new reference and our offset
3968 within it. If the new reference is the same size as the original, we
3969 won't optimize anything, so return zero. */
3979 /* Make the mask to be used against the extracted field. */
3986 /* If not comparing with constant, just rework the comparison
3987 and return. */
3991 unsigned_type,
3994 mask),
3997 unsigned_type,
4000 mask));
4002 /* Otherwise, we are handling the constant case. See if the constant is too
4003 big for the field. Warn and return a tree of for 0 (false) if so. We do
4004 this not only for its own sake, but to avoid having to test for this
4005 error case below. If we didn't, we might generate wrong code.
4007 For unsigned fields, the constant shifted right by the field length should
4008 be all zero. For signed fields, the high-order bits should agree with
4009 the sign bit. */
4012 {
4016 {
4020 }
4021 }
4022 else
4023 {
4027 {
4031 }
4032 }
4034 /* Single-bit compares should always be against zero. */
4036 {
4039 }
4041 /* Make a new bitfield reference, shift the constant over the
4042 appropriate number of bits and mask it with the computed mask
4043 (in case this was a signed field). If we changed it, make a new one. */
4046 {
4049 }
4059 rhs);
4060 }
4061 \f
4062 /* Subroutine for fold_truthop: decode a field reference.
4064 If EXP is a comparison reference, we return the innermost reference.
4066 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4067 set to the starting bit number.
4069 If the innermost field can be completely contained in a mode-sized
4070 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4072 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4073 otherwise it is not changed.
4075 *PUNSIGNEDP is set to the signedness of the field.
4077 *PMASK is set to the mask used. This is either contained in a
4078 BIT_AND_EXPR or derived from the width of the field.
4080 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4082 Return 0 if this is not a component reference or is one that we can't
4083 do anything with. */
4085 static tree
4090 {
4094 tree unsigned_type;
4097 /* All the optimizations using this function assume integer fields.
4098 There are problems with FP fields since the type_for_size call
4099 below can fail for, e.g., XFmode. */
4103 /* We are interested in the bare arrangement of bits, so strip everything
4104 that doesn't affect the machine mode. However, record the type of the
4105 outermost expression if it may matter below. */
4112 {
4118 }
4127 /* If the number of bits in the reference is the same as the bitsize of
4128 the outer type, then the outer type gives the signedness. Otherwise
4129 (in case of a small bitfield) the signedness is unchanged. */
4133 /* Compute the mask to access the bitfield. */
4142 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4150 }
4152 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4153 bit positions. */
4155 static int
4157 {
4160 tree tmask;
4164 return
4171 }
4173 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4174 represents the sign bit of EXP's type. If EXP represents a sign
4175 or zero extension, also test VAL against the unextended type.
4176 The return value is the (sub)expression whose sign bit is VAL,
4177 or NULL_TREE otherwise. */
4179 static tree
4181 {
4185 tree t;
4187 /* Tree EXP must have an integral type. */
4192 /* Tree VAL must be an integer constant. */
4199 {
4206 }
4207 else
4208 {
4215 }
4217 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4218 treat VAL as if it were unsigned. */
4223 /* Handle extension from a narrower type. */
4229 }
4231 /* Subroutine for fold_truthop: determine if an operand is simple enough
4232 to be evaluated unconditionally. */
4234 static int
4236 {
4237 /* Strip any conversions that don't change the machine mode. */
4246 /* Don't regard global variables as simple. They may be
4247 allocated in ways unknown to the compiler (shared memory,
4248 #pragma weak, etc). */
4251 /* Loading a static variable is unduly expensive, but global
4252 registers aren't expensive. */
4254 }
4255 \f
4256 /* The following functions are subroutines to fold_range_test and allow it to
4257 try to change a logical combination of comparisons into a range test.
4259 For example, both
4260 X == 2 || X == 3 || X == 4 || X == 5
4261 and
4262 X >= 2 && X <= 5
4263 are converted to
4264 (unsigned) (X - 2) <= 3
4266 We describe each set of comparisons as being either inside or outside
4267 a range, using a variable named like IN_P, and then describe the
4268 range with a lower and upper bound. If one of the bounds is omitted,
4269 it represents either the highest or lowest value of the type.
4271 In the comments below, we represent a range by two numbers in brackets
4272 preceded by a "+" to designate being inside that range, or a "-" to
4273 designate being outside that range, so the condition can be inverted by
4274 flipping the prefix. An omitted bound is represented by a "-". For
4275 example, "- [-, 10]" means being outside the range starting at the lowest
4276 possible value and ending at 10, in other words, being greater than 10.
4277 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4278 always false.
4280 We set up things so that the missing bounds are handled in a consistent
4281 manner so neither a missing bound nor "true" and "false" need to be
4282 handled using a special case. */
4284 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4285 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4286 and UPPER1_P are nonzero if the respective argument is an upper bound
4287 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4288 must be specified for a comparison. ARG1 will be converted to ARG0's
4289 type if both are specified. */
4291 static tree
4294 {
4295 tree tem;
4299 /* If neither arg represents infinity, do the normal operation.
4300 Else, if not a comparison, return infinity. Else handle the special
4301 comparison rules. Note that most of the cases below won't occur, but
4302 are handled for consistency. */
4305 {
4310 }
4315 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4316 for neither. In real maths, we cannot assume open ended ranges are
4317 the same. But, this is computer arithmetic, where numbers are finite.
4318 We can therefore make the transformation of any unbounded range with
4319 the value Z, Z being greater than any representable number. This permits
4320 us to treat unbounded ranges as equal. */
4324 {
4345 }
4348 }
4349 \f
4350 /* Given EXP, a logical expression, set the range it is testing into
4351 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4352 actually being tested. *PLOW and *PHIGH will be made of the same
4353 type as the returned expression. If EXP is not a comparison, we
4354 will most likely not be returning a useful value and range. Set
4355 *STRICT_OVERFLOW_P to true if the return value is only valid
4356 because signed overflow is undefined; otherwise, do not change
4357 *STRICT_OVERFLOW_P. */
4359 static tree
4362 {
4369 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4370 and see if we can refine the range. Some of the cases below may not
4371 happen, but it doesn't seem worth worrying about this. We "continue"
4372 the outer loop when we've changed something; otherwise we "break"
4373 the switch, which will "break" the while. */
4379 {
4384 {
4396 }
4399 {
4406 /* We can only do something if the range is testing for zero
4407 and if the second operand is an integer constant. Note that
4408 saying something is "in" the range we make is done by
4409 complementing IN_P since it will set in the initial case of
4410 being not equal to zero; "out" is leaving it alone. */
4417 {
4438 }
4440 /* If this is an unsigned comparison, we also know that EXP is
4441 greater than or equal to zero. We base the range tests we make
4442 on that fact, so we record it here so we can parse existing
4443 range tests. We test arg0_type since often the return type
4444 of, e.g. EQ_EXPR, is boolean. */
4446 {
4450 NULL_TREE))
4455 /* If the high bound is missing, but we have a nonzero low
4456 bound, reverse the range so it goes from zero to the low bound
4457 minus 1. */
4459 {
4464 }
4465 }
4471 /* (-x) IN [a,b] -> x in [-b, -a] */
4483 /* ~ X -> -X - 1 */
4492 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4493 move a constant to the other side. */
4498 /* If EXP is signed, any overflow in the computation is undefined,
4499 so we don't worry about it so long as our computations on
4500 the bounds don't overflow. For unsigned, overflow is defined
4501 and this is exactly the right thing. */
4513 /* Check for an unsigned range which has wrapped around the maximum
4514 value thus making n_high < n_low, and normalize it. */
4516 {
4522 /* If the range is of the form +/- [ x+1, x ], we won't
4523 be able to normalize it. But then, it represents the
4524 whole range or the empty set, so make it
4525 +/- [ -, - ]. */
4529 else
4531 }
4532 else
4556 /* If we're converting arg0 from an unsigned type, to exp,
4557 a signed type, we will be doing the comparison as unsigned.
4558 The tests above have already verified that LOW and HIGH
4559 are both positive.
4561 So we have to ensure that we will handle large unsigned
4562 values the same way that the current signed bounds treat
4563 negative values. */
4566 {
4567 tree high_positive;
4568 tree equiv_type;
4569 /* For fixed-point modes, we need to pass the saturating flag
4570 as the 2nd parameter. */
4575 else
4579 /* A range without an upper bound is, naturally, unbounded.
4580 Since convert would have cropped a very large value, use
4581 the max value for the destination type. */
4582 high_positive
4589 high_positive),
4592 /* If the low bound is specified, "and" the range with the
4593 range for which the original unsigned value will be
4594 positive. */
4596 {
4600 integer_zero_node),
4601 high_positive))
4605 }
4606 else
4607 {
4608 /* Otherwise, "or" the range with the range of the input
4609 that will be interpreted as negative. */
4613 integer_zero_node),
4614 high_positive))
4618 }
4619 }
4627 }
4630 }
4632 /* If EXP is a constant, we can evaluate whether this is true or false. */
4634 {
4641 }
4645 }
4646 \f
4647 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4648 type, TYPE, return an expression to test if EXP is in (or out of, depending
4649 on IN_P) the range. Return 0 if the test couldn't be created. */
4651 static tree
4653 {
4655 tree value;
4657 #ifdef HAVE_canonicalize_funcptr_for_compare
4658 /* Disable this optimization for function pointer expressions
4659 on targets that require function pointer canonicalization. */
4664 #endif
4667 {
4673 }
4691 {
4693 {
4697 }
4699 }
4701 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4703 {
4705 HOST_WIDE_INT hi;
4710 {
4713 }
4714 else
4715 {
4718 }
4721 {
4723 {
4726 etype
4728 else
4731 }
4734 }
4735 }
4737 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4738 This requires wrap-around arithmetics for the type of the expression. */
4740 {
4742 /* There is no requirement that LOW be within the range of ETYPE
4743 if the latter is a subtype. It must, however, be within the base
4744 type of ETYPE. So be sure we do the subtraction in that type. */
4757 }
4759 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4762 {
4765 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4766 for the type in question, as we rely on this here. */
4776 else
4778 }
4788 {
4790 {
4796 }
4798 }
4806 }
4807 \f
4808 /* Return the predecessor of VAL in its type, handling the infinite case. */
4810 static tree
4812 {
4818 else
4820 }
4822 /* Return the successor of VAL in its type, handling the infinite case. */
4824 static tree
4826 {
4832 else
4834 }
4836 /* Given two ranges, see if we can merge them into one. Return 1 if we
4837 can, 0 if we can't. Set the output range into the specified parameters. */
4839 static int
4842 {
4846 tree tem;
4856 /* Make range 0 be the range that starts first, or ends last if they
4857 start at the same value. Swap them if it isn't. */
4860 || (lowequal
4863 {
4867 }
4869 /* Now flag two cases, whether the ranges are disjoint or whether the
4870 second range is totally subsumed in the first. Note that the tests
4871 below are simplified by the ones above. */
4877 /* We now have four cases, depending on whether we are including or
4878 excluding the two ranges. */
4880 {
4881 /* If they don't overlap, the result is false. If the second range
4882 is a subset it is the result. Otherwise, the range is from the start
4883 of the second to the end of the first. */
4888 else
4890 }
4893 {
4894 /* If they don't overlap, the result is the first range. If they are
4895 equal, the result is false. If the second range is a subset of the
4896 first, and the ranges begin at the same place, we go from just after
4897 the end of the second range to the end of the first. If the second
4898 range is not a subset of the first, or if it is a subset and both
4899 ranges end at the same place, the range starts at the start of the
4900 first range and ends just before the second range.
4901 Otherwise, we can't describe this as a single range. */
4907 {
4912 {
4913 /* We are in the weird situation where high0 > high1 but
4914 high1 has no successor. Punt. */
4916 }
4917 }
4919 {
4924 {
4925 /* low0 < low1 but low1 has no predecessor. Punt. */
4927 }
4928 }
4929 else
4931 }
4934 {
4935 /* If they don't overlap, the result is the second range. If the second
4936 is a subset of the first, the result is false. Otherwise,
4937 the range starts just after the first range and ends at the
4938 end of the second. */
4943 else
4944 {
4949 {
4950 /* high1 > high0 but high0 has no successor. Punt. */
4952 }
4953 }
4954 }
4956 else
4957 {
4958 /* The case where we are excluding both ranges. Here the complex case
4959 is if they don't overlap. In that case, the only time we have a
4960 range is if they are adjacent. If the second is a subset of the
4961 first, the result is the first. Otherwise, the range to exclude
4962 starts at the beginning of the first range and ends at the end of the
4963 second. */
4965 {
4970 else
4971 {
4972 /* Canonicalize - [min, x] into - [-, x]. */
4975 {
4980 /* FALLTHROUGH */
4993 }
4995 /* Canonicalize - [x, max] into - [x, -]. */
4998 {
5003 /* FALLTHROUGH */
5018 }
5020 /* The ranges might be also adjacent between the maximum and
5021 minimum values of the given type. For
5022 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5023 return + [x + 1, y - 1]. */
5025 {
5032 }
5033 else
5035 }
5036 }
5039 else
5041 }
5045 }
5046 \f
5048 /* Subroutine of fold, looking inside expressions of the form
5049 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5050 of the COND_EXPR. This function is being used also to optimize
5051 A op B ? C : A, by reversing the comparison first.
5053 Return a folded expression whose code is not a COND_EXPR
5054 anymore, or NULL_TREE if no folding opportunity is found. */
5056 static tree
5058 {
5063 tree tem;
5068 /* If we have A op 0 ? A : -A, consider applying the following
5069 transformations:
5071 A == 0? A : -A same as -A
5072 A != 0? A : -A same as A
5073 A >= 0? A : -A same as abs (A)
5074 A > 0? A : -A same as abs (A)
5075 A <= 0? A : -A same as -abs (A)
5076 A < 0? A : -A same as -abs (A)
5078 None of these transformations work for modes with signed
5079 zeros. If A is +/-0, the first two transformations will
5080 change the sign of the result (from +0 to -0, or vice
5081 versa). The last four will fix the sign of the result,
5082 even though the original expressions could be positive or
5083 negative, depending on the sign of A.
5085 Note that all these transformations are correct if A is
5086 NaN, since the two alternatives (A and -A) are also NaNs. */
5093 /* In the case that A is of the form X-Y, '-A' (arg2) may
5094 have already been folded to Y-X, check for that. */
5102 {
5114 /* Fall through. */
5136 }
5138 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5139 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5140 both transformations are correct when A is NaN: A != 0
5141 is then true, and A == 0 is false. */
5145 {
5150 }
5152 /* Try some transformations of A op B ? A : B.
5154 A == B? A : B same as B
5155 A != B? A : B same as A
5156 A >= B? A : B same as max (A, B)
5157 A > B? A : B same as max (B, A)
5158 A <= B? A : B same as min (A, B)
5159 A < B? A : B same as min (B, A)
5161 As above, these transformations don't work in the presence
5162 of signed zeros. For example, if A and B are zeros of
5163 opposite sign, the first two transformations will change
5164 the sign of the result. In the last four, the original
5165 expressions give different results for (A=+0, B=-0) and
5166 (A=-0, B=+0), but the transformed expressions do not.
5168 The first two transformations are correct if either A or B
5169 is a NaN. In the first transformation, the condition will
5170 be false, and B will indeed be chosen. In the case of the
5171 second transformation, the condition A != B will be true,
5172 and A will be chosen.
5174 The conversions to max() and min() are not correct if B is
5175 a number and A is not. The conditions in the original
5176 expressions will be false, so all four give B. The min()
5177 and max() versions would give a NaN instead. */
5180 /* Avoid these transformations if the COND_EXPR may be used
5181 as an lvalue in the C++ front-end. PR c++/19199. */
5182 && (in_gimple_form
5187 {
5192 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5194 {
5198 }
5201 {
5210 /* In C++ a ?: expression can be an lvalue, so put the
5211 operand which will be used if they are equal first
5212 so that we can convert this back to the
5213 corresponding COND_EXPR. */
5215 {
5222 }
5229 {
5236 }
5249 }
5250 }
5252 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5253 we might still be able to simplify this. For example,
5254 if C1 is one less or one more than C2, this might have started
5255 out as a MIN or MAX and been transformed by this function.
5256 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5262 {
5264 /* We can replace A with C1 in this case. */
5269 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5270 MIN_EXPR, to preserve the signedness of the comparison. */
5272 OEP_ONLY_CONST)
5276 OEP_ONLY_CONST))
5277 {
5281 }
5285 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5286 as above. */
5288 OEP_ONLY_CONST)
5292 OEP_ONLY_CONST))
5293 {
5297 }
5301 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5302 MAX_EXPR, to preserve the signedness of the comparison. */
5304 OEP_ONLY_CONST)
5308 OEP_ONLY_CONST))
5309 {
5313 }
5317 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5319 OEP_ONLY_CONST)
5323 OEP_ONLY_CONST))
5324 {
5328 }
5334 }
5337 }
5340 \f
5341 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5342 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5343 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5344 false) >= 2)
5345 #endif
5347 /* EXP is some logical combination of boolean tests. See if we can
5348 merge it into some range test. Return the new tree if so. */
5350 static tree
5352 {
5360 tree tem;
5364 /* If this is an OR operation, invert both sides; we will invert
5365 again at the end. */
5369 /* If both expressions are the same, if we can merge the ranges, and we
5370 can build the range test, return it or it inverted. If one of the
5371 ranges is always true or always false, consider it to be the same
5372 expression as the other. */
5380 {
5384 }
5386 /* On machines where the branch cost is expensive, if this is a
5387 short-circuited branch and the underlying object on both sides
5388 is the same, make a non-short-circuit operation. */
5394 {
5395 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5396 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5397 which cases we can't do this. */
5405 {
5414 {
5417 WARN_STRICT_OVERFLOW_COMPARISON);
5421 }
5422 }
5423 }
5426 }
5427 \f
5428 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5429 bit value. Arrange things so the extra bits will be set to zero if and
5430 only if C is signed-extended to its full width. If MASK is nonzero,
5431 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5433 static tree
5435 {
5438 tree temp;
5443 /* We work by getting just the sign bit into the low-order bit, then
5444 into the high-order bit, then sign-extend. We then XOR that value
5445 with C. */
5449 /* We must use a signed type in order to get an arithmetic right shift.
5450 However, we must also avoid introducing accidental overflows, so that
5451 a subsequent call to integer_zerop will work. Hence we must
5452 do the type conversion here. At this point, the constant is either
5453 zero or one, and the conversion to a signed type can never overflow.
5454 We could get an overflow if this conversion is done anywhere else. */
5463 /* If necessary, convert the type back to match the type of C. */
5468 }
5469 \f
5470 /* Find ways of folding logical expressions of LHS and RHS:
5471 Try to merge two comparisons to the same innermost item.
5472 Look for range tests like "ch >= '0' && ch <= '9'".
5473 Look for combinations of simple terms on machines with expensive branches
5474 and evaluate the RHS unconditionally.
5476 For example, if we have p->a == 2 && p->b == 4 and we can make an
5477 object large enough to span both A and B, we can do this with a comparison
5478 against the object ANDed with the a mask.
5480 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5481 operations to do this with one comparison.
5483 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5484 function and the one above.
5486 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5487 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5489 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5490 two operands.
5492 We return the simplified tree or 0 if no optimization is possible. */
5494 static tree
5496 {
5497 /* If this is the "or" of two comparisons, we can do something if
5498 the comparisons are NE_EXPR. If this is the "and", we can do something
5499 if the comparisons are EQ_EXPR. I.e.,
5500 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5502 WANTED_CODE is this operation code. For single bit fields, we can
5503 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5504 comparison for one-bit fields. */
5526 /* Start by getting the comparison codes. Fail if anything is volatile.
5527 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5528 it were surrounded with a NE_EXPR. */
5537 {
5541 }
5544 {
5548 }
5559 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5562 {
5563 tree result;
5566 {
5571 }
5574 {
5580 }
5581 }
5586 /* If the RHS can be evaluated unconditionally and its operands are
5587 simple, it wins to evaluate the RHS unconditionally on machines
5588 with expensive branches. In this case, this isn't a comparison
5589 that can be merged. Avoid doing this if the RHS is a floating-point
5590 comparison since those can trap. */
5597 {
5598 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5609 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5621 {
5625 }
5626 }
5628 /* See if the comparisons can be merged. Then get all the parameters for
5629 each side. */
5653 /* It must be true that the inner operation on the lhs of each
5654 comparison must be the same if we are to be able to do anything.
5655 Then see if we have constants. If not, the same must be true for
5656 the rhs's. */
5667 else
5670 /* If either comparison code is not correct for our logical operation,
5671 fail. However, we can convert a one-bit comparison against zero into
5672 the opposite comparison against that bit being set in the field. */
5676 {
5678 {
5679 /* Make the left operand unsigned, since we are only interested
5680 in the value of one bit. Otherwise we are doing the wrong
5681 thing below. */
5684 }
5685 else
5687 }
5689 /* This is analogous to the code for l_const above. */
5691 {
5693 {
5696 }
5697 else
5699 }
5701 /* See if we can find a mode that contains both fields being compared on
5702 the left. If we can't, fail. Otherwise, update all constants and masks
5703 to be relative to a field of that size. */
5708 volatilep);
5718 {
5721 }
5729 {
5737 {
5741 }
5742 }
5744 {
5752 {
5756 }
5757 }
5759 /* If the right sides are not constant, do the same for it. Also,
5760 disallow this optimization if a size or signedness mismatch occurs
5761 between the left and right sides. */
5763 {
5766 /* Make sure the two fields on the right
5767 correspond to the left without being swapped. */
5775 volatilep);
5785 {
5788 }
5795 /* Make a mask that corresponds to both fields being compared.
5796 Do this for both items being compared. If the operands are the
5797 same size and the bits being compared are in the same position
5798 then we can do this by masking both and comparing the masked
5799 results. */
5803 {
5815 }
5817 /* There is still another way we can do something: If both pairs of
5818 fields being compared are adjacent, we may be able to make a wider
5819 field containing them both.
5821 Note that we still must mask the lhs/rhs expressions. Furthermore,
5822 the mask must be shifted to account for the shift done by
5823 make_bit_field_ref. */
5828 {
5829 tree type;
5841 /* Convert to the smaller type before masking out unwanted bits. */
5844 {
5846 {
5850 }
5852 {
5856 }
5857 }
5866 }
5869 }
5871 /* Handle the case of comparisons with constants. If there is something in
5872 common between the masks, those bits of the constants must be the same.
5873 If not, the condition is always false. Test for this to avoid generating
5874 incorrect code below. */
5879 {
5881 {
5884 }
5885 else
5886 {
5889 }
5890 }
5892 /* Construct the expression we will return. First get the component
5893 reference we will make. Unless the mask is all ones the width of
5894 that field, perform the mask operation. Then compare with the
5895 merged constant. */
5905 }
5906 \f
5907 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5908 constant. */
5910 static tree
5912 {
5915 tree comp_const;
5916 tree minmax_const;
5918 tree inner;
5929 /* If something does not permit us to optimize, return the original tree. */
5937 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5938 and GT_EXPR, doing the rest with recursive calls using logical
5939 simplifications. */
5941 {
5943 {
5949 }
5952 return
5954 optimize_minmax_comparison
5956 optimize_minmax_comparison
5961 /* MAX (X, 0) == 0 -> X <= 0 */
5965 /* MAX (X, 0) == 5 -> X == 5 */
5969 /* MAX (X, 0) == -1 -> false */
5973 /* MIN (X, 0) == 0 -> X >= 0 */
5977 /* MIN (X, 0) == 5 -> false */
5980 else
5981 /* MIN (X, 0) == -1 -> X == -1 */
5986 /* MAX (X, 0) > 0 -> X > 0
5987 MAX (X, 0) > 5 -> X > 5 */
5991 /* MAX (X, 0) > -1 -> true */
5995 /* MIN (X, 0) > 0 -> false
5996 MIN (X, 0) > 5 -> false */
5999 else
6000 /* MIN (X, 0) > -1 -> X > -1 */
6005 }
6006 }
6007 \f
6008 /* T is an integer expression that is being multiplied, divided, or taken a
6009 modulus (CODE says which and what kind of divide or modulus) by a
6010 constant C. See if we can eliminate that operation by folding it with
6011 other operations already in T. WIDE_TYPE, if non-null, is a type that
6012 should be used for the computation if wider than our type.
6014 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6015 (X * 2) + (Y * 4). We must, however, be assured that either the original
6016 expression would not overflow or that overflow is undefined for the type
6017 in the language in question.
6019 If we return a non-null expression, it is an equivalent form of the
6020 original computation, but need not be in the original type.
6022 We set *STRICT_OVERFLOW_P to true if the return values depends on
6023 signed overflow being undefined. Otherwise we do not change
6024 *STRICT_OVERFLOW_P. */
6026 static tree
6029 {
6030 /* To avoid exponential search depth, refuse to allow recursion past
6031 three levels. Beyond that (1) it's highly unlikely that we'll find
6032 something interesting and (2) we've probably processed it before
6033 when we built the inner expression. */
6036 tree ret;
6041 depth++;
6043 depth--;
6046 }
6048 static tree
6051 {
6062 /* Don't deal with constants of zero here; they confuse the code below. */
6072 /* Note that we need not handle conditional operations here since fold
6073 already handles those cases. So just do arithmetic here. */
6075 {
6077 /* For a constant, we can always simplify if we are a multiply
6078 or (for divide and modulus) if it is a multiple of our constant. */
6086 /* If op0 is an expression ... */
6092 /* ... and has wrapping overflow, and its type is smaller
6093 than ctype, then we cannot pass through as widening. */
6099 /* ... or this is a truncation (t is narrower than op0),
6100 then we cannot pass through this narrowing. */
6103 /* ... or signedness changes for division or modulus,
6104 then we cannot pass through this conversion. */
6108 /* ... or has undefined overflow while the converted to
6109 type has not, we cannot do the operation in the inner type
6110 as that would introduce undefined overflow. */
6115 /* Pass the constant down and see if we can make a simplification. If
6116 we can, replace this expression with the inner simplification for
6117 possible later conversion to our or some other type. */
6122 code == MULT_EXPR
6124 strict_overflow_p))))
6129 /* If widening the type changes it from signed to unsigned, then we
6130 must avoid building ABS_EXPR itself as unsigned. */
6132 {
6136 {
6139 }
6141 }
6142 /* If the constant is negative, we cannot simplify this. */
6145 /* FALLTHROUGH */
6153 /* If widening the type changes the signedness, then we can't perform
6154 this optimization as that changes the result. */
6158 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6164 {
6171 }
6175 /* If the second operand is constant, this is a multiplication
6176 or floor division, by a power of two, so we can treat it that
6177 way unless the multiplier or divisor overflows. Signed
6178 left-shift overflow is implementation-defined rather than
6179 undefined in C90, so do not convert signed left shift into
6180 multiplication. */
6183 /* const_binop may not detect overflow correctly,
6184 so check for it explicitly here. */
6189 size_one_node,
6199 /* See if we can eliminate the operation on both sides. If we can, we
6200 can return a new PLUS or MINUS. If we can't, the only remaining
6201 cases where we can do anything are if the second operand is a
6202 constant. */
6208 /* If not multiplication, we can only do this if both operands
6209 are divisible by c. */
6212 {
6217 }
6219 /* If this was a subtraction, negate OP1 and set it to be an addition.
6220 This simplifies the logic below. */
6227 /* If either OP1 or C are negative, this optimization is not safe for
6228 some of the division and remainder types while for others we need
6229 to change the code. */
6231 {
6239 }
6241 /* If it's a multiply or a division/modulus operation of a multiple
6242 of our constant, do the operation and verify it doesn't overflow. */
6245 {
6248 /* We allow the constant to overflow with wrapping semantics. */
6252 }
6253 else
6256 /* If we have an unsigned type is not a sizetype, we cannot widen
6257 the operation since it will change the result if the original
6258 computation overflowed. */
6264 /* If we were able to eliminate our operation from the first side,
6265 apply our operation to the second side and reform the PLUS. */
6269 /* The last case is if we are a multiply. In that case, we can
6270 apply the distributive law to commute the multiply and addition
6271 if the multiplication of the constants doesn't overflow. */
6277 op1);
6282 /* We have a special case here if we are doing something like
6283 (C * 8) % 4 since we know that's zero. */
6286 /* If the multiplication can overflow we cannot optimize this.
6287 ??? Until we can properly mark individual operations as
6288 not overflowing we need to treat sizetype special here as
6289 stor-layout relies on this opimization to make
6290 DECL_FIELD_BIT_OFFSET always a constant. */
6296 {
6299 }
6301 /* ... fall through ... */
6305 /* If we can extract our operation from the LHS, do so and return a
6306 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6307 do something only if the second operand is a constant. */
6321 /* If these are the same operation types, we can associate them
6322 assuming no overflow. */
6334 /* If these operations "cancel" each other, we have the main
6335 optimizations of this pass, which occur when either constant is a
6336 multiple of the other, in which case we replace this with either an
6337 operation or CODE or TCODE.
6339 If we have an unsigned type that is not a sizetype, we cannot do
6340 this since it will change the result if the original computation
6341 overflowed. */
6349 {
6351 {
6358 }
6360 {
6367 }
6368 }
6373 }
6376 }
6377 \f
6378 /* Return a node which has the indicated constant VALUE (either 0 or
6379 1), and is of the indicated TYPE. */
6381 tree
6383 {
6388 else
6390 }
6393 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6394 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6395 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6396 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6397 COND is the first argument to CODE; otherwise (as in the example
6398 given here), it is the second argument. TYPE is the type of the
6399 original expression. Return NULL_TREE if no simplification is
6400 possible. */
6402 static tree
6406 {
6413 /* This transformation is only worthwhile if we don't have to wrap
6414 arg in a SAVE_EXPR, and the operation can be simplified on at least
6415 one of the branches once its pushed inside the COND_EXPR. */
6420 {
6424 /* If this operand throws an expression, then it does not make
6425 sense to try to perform a logical or arithmetic operation
6426 involving it. */
6431 }
6432 else
6433 {
6438 }
6442 {
6446 else
6448 }
6450 {
6454 else
6456 }
6460 }
6462 \f
6463 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6465 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6466 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6467 ADDEND is the same as X.
6469 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6470 and finite. The problematic cases are when X is zero, and its mode
6471 has signed zeros. In the case of rounding towards -infinity,
6472 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6473 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6475 bool
6477 {
6481 /* Don't allow the fold with -fsignaling-nans. */
6485 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6489 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6494 /* The mode has signed zeros, and we have to honor their sign.
6495 In this situation, there is only one case we can return true for.
6496 X - 0 is the same as X unless rounding towards -infinity is
6497 supported. */
6499 }
6501 /* Subroutine of fold() that checks comparisons of built-in math
6502 functions against real constants.
6504 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6505 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6506 is the type of the result and ARG0 and ARG1 are the operands of the
6507 comparison. ARG1 must be a TREE_REAL_CST.
6509 The function returns the constant folded tree if a simplification
6510 can be made, and NULL_TREE otherwise. */
6512 static tree
6515 {
6516 REAL_VALUE_TYPE c;
6519 {
6525 {
6526 /* sqrt(x) < y is always false, if y is negative. */
6530 /* sqrt(x) > y is always true, if y is negative and we
6531 don't care about NaNs, i.e. negative values of x. */
6535 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6538 }
6540 {
6541 REAL_VALUE_TYPE c2;
6547 {
6548 /* sqrt(x) > y is x == +Inf, when y is very large. */
6553 /* sqrt(x) > y is always false, when y is very large
6554 and we don't care about infinities. */
6556 }
6558 /* sqrt(x) > c is the same as x > c*c. */
6561 }
6563 {
6564 REAL_VALUE_TYPE c2;
6570 {
6571 /* sqrt(x) < y is always true, when y is a very large
6572 value and we don't care about NaNs or Infinities. */
6576 /* sqrt(x) < y is x != +Inf when y is very large and we
6577 don't care about NaNs. */
6582 /* sqrt(x) < y is x >= 0 when y is very large and we
6583 don't care about Infinities. */
6588 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6597 dconst0)),
6600 c2)));
6601 }
6603 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6608 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6611 {
6616 dconst0)),
6619 c2)));
6620 }
6621 }
6622 }
6625 }
6627 /* Subroutine of fold() that optimizes comparisons against Infinities,
6628 either +Inf or -Inf.
6630 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6631 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6632 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6634 The function returns the constant folded tree if a simplification
6635 can be made, and NULL_TREE otherwise. */
6637 static tree
6639 {
6641 REAL_VALUE_TYPE max;
6642 tree temp;
6647 /* For negative infinity swap the sense of the comparison. */
6653 {
6655 /* x > +Inf is always false, if with ignore sNANs. */
6661 /* x <= +Inf is always true, if we don't case about NaNs. */
6665 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6668 {
6671 }
6676 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6682 /* x < +Inf is always equal to x <= DBL_MAX. */
6688 /* x != +Inf is always equal to !(x > DBL_MAX). */
6700 }
6703 }
6705 /* Subroutine of fold() that optimizes comparisons of a division by
6706 a nonzero integer constant against an integer constant, i.e.
6707 X/C1 op C2.
6709 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6710 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6711 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6713 The function returns the constant folded tree if a simplification
6714 can be made, and NULL_TREE otherwise. */
6716 static tree
6718 {
6723 HOST_WIDE_INT hpart;
6728 /* We have to do this the hard way to detect unsigned overflow.
6729 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6740 {
6745 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6753 }
6755 {
6759 {
6778 }
6779 }
6780 else
6781 {
6782 /* A negative divisor reverses the relational operators. */
6788 {
6807 }
6808 }
6811 {
6832 {
6835 }
6840 {
6843 }
6848 {
6851 }
6856 {
6859 }
6864 }
6867 }
6870 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6871 equality/inequality test, then return a simplified form of the test
6872 using a sign testing. Otherwise return NULL. TYPE is the desired
6873 result type. */
6875 static tree
6877 tree result_type)
6878 {
6879 /* If this is testing a single bit, we can optimize the test. */
6883 {
6884 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6885 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6889 /* This is only a win if casting to a signed type is cheap,
6890 i.e. when arg00's type is not a partial mode. */
6893 {
6898 }
6899 }
6902 }
6904 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6905 equality/inequality test, then return a simplified form of
6906 the test using shifts and logical operations. Otherwise return
6907 NULL. TYPE is the desired result type. */
6909 tree
6911 tree result_type)
6912 {
6913 /* If this is testing a single bit, we can optimize the test. */
6917 {
6926 /* First, see if we can fold the single bit test into a sign-bit
6927 test. */
6929 result_type);
6933 /* Otherwise we have (A & C) != 0 where C is a single bit,
6934 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6935 Similarly for (A & C) == 0. */
6937 /* If INNER is a right shift of a constant and it plus BITNUM does
6938 not overflow, adjust BITNUM and INNER. */
6945 {
6948 }
6950 /* If we are going to be able to omit the AND below, we must do our
6951 operations as unsigned. If we must use the AND, we have a choice.
6952 Normally unsigned is faster, but for some machines signed is. */
6953 #ifdef LOAD_EXTEND_OP
6956 #else
6958 #endif
6974 /* Put the AND last so it can combine with more things. */
6977 /* Make sure to return the proper type. */
6981 }
6983 }
6985 /* Check whether we are allowed to reorder operands arg0 and arg1,
6986 such that the evaluation of arg1 occurs before arg0. */
6988 static bool
6990 {
6997 }
6999 /* Test whether it is preferable two swap two operands, ARG0 and
7000 ARG1, for example because ARG0 is an integer constant and ARG1
7001 isn't. If REORDER is true, only recommend swapping if we can
7002 evaluate the operands in reverse order. */
7004 bool
7006 {
7042 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7043 for commutative and comparison operators. Ensuring a canonical
7044 form allows the optimizers to find additional redundancies without
7045 having to explicitly check for both orderings. */
7051 /* Put SSA_NAMEs last. */
7057 /* Put variables last. */
7064 }
7066 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7067 ARG0 is extended to a wider type. */
7069 static tree
7071 {
7073 tree arg1_unw;
7082 #ifdef HAVE_canonicalize_funcptr_for_compare
7083 /* Disable this optimization if we're casting a function pointer
7084 type on targets that require function pointer canonicalization. */
7089 #endif
7096 /* If possible, express the comparison in the shorter mode. */
7116 /* If we are comparing with the integer that does not fit into the range
7117 of the shorter type, the result is known. */
7128 {
7155 }
7158 }
7160 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7161 ARG0 just the signedness is changed. */
7163 static tree
7166 {
7167 tree arg0_inner;
7177 #ifdef HAVE_canonicalize_funcptr_for_compare
7178 /* Disable this optimization if we're casting a function pointer
7179 type on targets that require function pointer canonicalization. */
7184 #endif
7189 /* If the conversion is from an integral subtype to its basetype
7190 leave it alone. */
7209 else
7213 }
7215 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7216 step of the array. Reconstructs s and delta in the case of s * delta
7217 being an integer constant (and thus already folded).
7218 ADDR is the address. MULT is the multiplicative expression.
7219 If the function succeeds, the new address expression is returned. Otherwise
7220 NULL_TREE is returned. */
7222 static tree
7224 {
7228 tree itype;
7231 /* Strip the nops that might be added when converting op1 to sizetype. */
7234 /* Canonicalize op1 into a possibly non-constant delta
7235 and an INTEGER_CST s. */
7237 {
7244 {
7247 }
7249 {
7252 }
7253 else
7255 }
7257 {
7260 }
7261 else
7262 {
7263 /* Simulate we are delta * 1. */
7266 }
7269 {
7271 {
7272 /* Remember if this was a multi-dimensional array. */
7285 {
7288 }
7289 else
7290 {
7291 /* Try if delta is a multiple of step. */
7296 }
7298 /* Only fold here if we can verify we do not overflow one
7299 dimension of a multi-dimensional array. */
7301 {
7302 tree tmp;
7318 }
7321 }
7322 else
7327 }
7329 /* We found the suitable array reference. So copy everything up to it,
7330 and replace the index. */
7337 {
7341 }
7349 }
7352 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7353 means A >= Y && A != MAX, but in this case we know that
7354 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7356 static tree
7358 {
7365 else
7374 {
7377 }
7379 {
7382 }
7383 else
7390 {
7391 /* Convert the pointer types into integer before taking the difference. */
7395 }
7396 else
7403 }
7405 /* Fold a sum or difference of at least one multiplication.
7406 Returns the folded tree or NULL if no simplification could be made. */
7408 static tree
7410 {
7414 /* (A * C) +- (B * C) -> (A+-B) * C.
7415 (A * C) +- A -> A * (C+-1).
7416 We are most concerned about the case where C is a constant,
7417 but other combinations show up during loop reduction. Since
7418 it is not difficult, try all four possibilities. */
7421 {
7424 }
7426 {
7429 }
7430 else
7431 {
7432 /* We cannot generate constant 1 for fract. */
7437 }
7439 {
7442 }
7444 {
7446 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7447 the purpose of this canonicalization. */
7451 {
7454 }
7455 else
7457 }
7458 else
7459 {
7460 /* We cannot generate constant 1 for fract. */
7465 }
7477 /* No identical multiplicands; see if we can find a common
7478 power-of-two factor in non-power-of-two multiplies. This
7479 can help in multi-dimensional array access. */
7482 {
7485 tree maybe_same;
7489 /* Move min of absolute values to int11. */
7492 {
7497 }
7498 else
7502 {
7510 }
7511 }
7521 }
7523 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7524 specified by EXPR into the buffer PTR of length LEN bytes.
7525 Return the number of bytes placed in the buffer, or zero
7526 upon failure. */
7528 static int
7530 {
7541 {
7545 else
7550 {
7557 else
7559 }
7560 else
7563 }
7565 }
7568 /* Subroutine of native_encode_expr. Encode the REAL_CST
7569 specified by EXPR into the buffer PTR of length LEN bytes.
7570 Return the number of bytes placed in the buffer, or zero
7571 upon failure. */
7573 static int
7575 {
7581 /* There are always 32 bits in each long, no matter the size of
7582 the hosts long. We handle floating point representations with
7583 up to 192 bits. */
7594 {
7599 {
7606 else
7608 }
7609 else
7612 }
7614 }
7616 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7617 specified by EXPR into the buffer PTR of length LEN bytes.
7618 Return the number of bytes placed in the buffer, or zero
7619 upon failure. */
7621 static int
7623 {
7625 tree part;
7636 }
7639 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7640 specified by EXPR into the buffer PTR of length LEN bytes.
7641 Return the number of bytes placed in the buffer, or zero
7642 upon failure. */
7644 static int
7646 {
7656 {
7658 {
7661 }
7662 else
7666 {
7669 }
7670 else
7671 {
7675 }
7677 }
7679 }
7682 /* Subroutine of native_encode_expr. Encode the STRING_CST
7683 specified by EXPR into the buffer PTR of length LEN bytes.
7684 Return the number of bytes placed in the buffer, or zero
7685 upon failure. */
7687 static int
7689 {
7691 HOST_WIDE_INT total_bytes;
7702 {
7706 }
7707 else
7710 }
7713 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7714 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7715 buffer PTR of length LEN bytes. Return the number of bytes
7716 placed in the buffer, or zero upon failure. */
7718 int
7720 {
7722 {
7740 }
7741 }
7744 /* Subroutine of native_interpret_expr. Interpret the contents of
7745 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7746 If the buffer cannot be interpreted, return NULL_TREE. */
7748 static tree
7750 {
7764 {
7767 {
7774 else
7776 }
7777 else
7783 else
7786 }
7789 }
7792 /* Subroutine of native_interpret_expr. Interpret the contents of
7793 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7794 If the buffer cannot be interpreted, return NULL_TREE. */
7796 static tree
7798 {
7803 /* There are always 32 bits in each long, no matter the size of
7804 the hosts long. We handle floating point representations with
7805 up to 192 bits. */
7806 REAL_VALUE_TYPE r;
7817 {
7820 {
7827 else
7829 }
7830 else
7835 }
7839 }
7842 /* Subroutine of native_interpret_expr. Interpret the contents of
7843 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7844 If the buffer cannot be interpreted, return NULL_TREE. */
7846 static tree
7848 {
7863 }
7866 /* Subroutine of native_interpret_expr. Interpret the contents of
7867 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7868 If the buffer cannot be interpreted, return NULL_TREE. */
7870 static tree
7872 {
7884 {
7889 }
7891 }
7894 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7895 the buffer PTR of length LEN as a constant of type TYPE. For
7896 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7897 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7898 return NULL_TREE. */
7900 tree
7902 {
7904 {
7921 }
7922 }
7925 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7926 TYPE at compile-time. If we're unable to perform the conversion
7927 return NULL_TREE. */
7929 static tree
7931 {
7932 /* We support up to 512-bit values (for V8DFmode). */
7936 /* Check that the host and target are sane. */
7945 }
7947 /* Build an expression for the address of T. Folds away INDIRECT_REF
7948 to avoid confusing the gimplify process. When IN_FOLD is true
7949 avoid modifications of T. */
7951 static tree
7953 {
7954 /* The size of the object is not relevant when talking about its address. */
7958 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7961 {
7966 }
7968 {
7978 }
7979 else
7983 }
7985 /* Build an expression for the address of T with type PTRTYPE. This
7986 function modifies the input parameter 'T' by sometimes setting the
7987 TREE_ADDRESSABLE flag. */
7989 tree
7991 {
7993 }
7995 /* Build an expression for the address of T. This function modifies
7996 the input parameter 'T' by sometimes setting the TREE_ADDRESSABLE
7997 flag. When called from fold functions, use fold_addr_expr instead. */
7999 tree
8001 {
8005 }
8007 /* Same as build_fold_addr_expr, builds an expression for the address
8008 of T, but avoids touching the input node 't'. Fold functions
8009 should use this version. */
8011 static tree
8013 {
8017 }
8019 /* Fold a unary expression of code CODE and type TYPE with operand
8020 OP0. Return the folded expression if folding is successful.
8021 Otherwise, return NULL_TREE. */
8023 tree
8025 {
8026 tree tem;
8027 tree arg0;
8035 {
8038 {
8039 /* Don't use STRIP_NOPS, because signedness of argument type
8040 matters. */
8042 }
8043 else
8044 {
8045 /* Strip any conversions that don't change the mode. This
8046 is safe for every expression, except for a comparison
8047 expression because its signedness is derived from its
8048 operands.
8050 Note that this is done as an internal manipulation within
8051 the constant folder, in order to find the simplest
8052 representation of the arguments so that their form can be
8053 studied. In any cases, the appropriate type conversions
8054 should be put back in the tree that will get out of the
8055 constant folder. */
8057 }
8058 }
8061 {
8068 {
8080 /* If this was a conversion, and all we did was to move into
8081 inside the COND_EXPR, bring it back out. But leave it if
8082 it is a conversion from integer to integer and the
8083 result precision is no wider than a word since such a
8084 conversion is cheap and may be optimized away by combine,
8085 while it couldn't if it were outside the COND_EXPR. Then return
8086 so we don't get into an infinite recursion loop taking the
8087 conversion out and then back in. */
8099 && (INTEGRAL_TYPE_P
8111 }
8113 {
8115 {
8119 }
8123 integer_one_node),
8125 integer_zero_node));
8126 }
8127 }
8130 {
8132 /* Re-association barriers around constants and other re-association
8133 barriers can be removed. */
8139 CASE_CONVERT:
8145 /* If we have (type) (a CMP b) and type is an integral type, return
8146 new expression involving the new type. */
8151 /* Handle cases of two conversions in a row. */
8153 {
8175 /* In addition to the cases of two conversions in a row
8176 handled below, if we are converting something to its own
8177 type via an object of identical or wider precision, neither
8178 conversion is needed. */
8185 /* Likewise, if the intermediate and initial types are either both
8186 float or both integer, we don't need the middle conversion if the
8187 former is wider than the latter and doesn't change the signedness
8188 (for integers). Avoid this if the final type is a pointer since
8189 then we sometimes need the middle conversion. Likewise if the
8190 final type has a precision not equal to the size of its mode. */
8199 && ! final_ptr
8203 /* If we have a sign-extension of a zero-extended value, we can
8204 replace that by a single zero-extension. */
8210 /* Two conversions in a row are not needed unless:
8211 - some conversion is floating-point (overstrict for now), or
8212 - some conversion is a vector (overstrict for now), or
8213 - the intermediate type is narrower than both initial and
8214 final, or
8215 - the intermediate type and innermost type differ in signedness,
8216 and the outermost type is wider than the intermediate, or
8217 - the initial type is a pointer type and the precisions of the
8218 intermediate and final types differ, or
8219 - the final type is a pointer type and the precisions of the
8220 initial and intermediate types differ. */
8234 }
8236 /* Handle (T *)&A.B.C for A being of type T and B and C
8237 living at offset zero. This occurs frequently in
8238 C++ upcasting and then accessing the base. */
8242 {
8244 tree offset;
8250 /* If the reference was to a (constant) zero offset, we can use
8251 the address of the base if it has the same base type
8252 as the result type. */
8257 }
8261 /* Detect assigning a bitfield. */
8263 && DECL_BIT_FIELD
8265 {
8266 /* Don't leave an assignment inside a conversion
8267 unless assigning a bitfield. */
8269 /* First do the assignment, then return converted constant. */
8274 }
8276 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8277 constants (if x has signed type, the sign bit cannot be set
8278 in c). This folds extension into the BIT_AND_EXPR.
8279 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8280 very likely don't have maximal range for their precision and this
8281 transformation effectively doesn't preserve non-maximal ranges. */
8285 /* Not if the conversion is to the sub-type. */
8287 {
8297 <= HOST_BITS_PER_WIDE_INT
8299 {
8306 #ifdef LOAD_EXTEND_OP
8308 && !flag_syntax_only
8311 {
8315 }
8316 #endif
8317 }
8319 {
8325 }
8326 }
8328 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8329 when one of the new casts will fold away. Conservatively we assume
8330 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8336 {
8342 }
8344 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8345 of the same precision, and X is an integer type not narrower than
8346 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8352 {
8357 }
8359 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8360 type of X and Y (integer types only). */
8365 {
8366 /* Be careful not to introduce new overflows. */
8367 tree mult_type;
8370 else
8374 {
8381 }
8382 }
8397 /* For integral conversions with the same precision or pointer
8398 conversions use a NOP_EXPR instead. */
8404 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8405 a sub-type to its base type as generated by the Ada FE. */
8410 /* Strip inner integral conversions that do not change the precision. */
8433 /* Convert fabs((double)float) into (double)fabsf(float). */
8436 {
8441 targ0));
8442 }
8443 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8449 /* Strip sign ops from argument. */
8451 {
8455 }
8462 {
8467 }
8469 {
8474 }
8484 /* Convert ~ (-A) to A - 1. */
8489 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8497 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8510 /* Perform BIT_NOT_EXPR on each element individually. */
8512 {
8517 {
8519 {
8525 }
8526 else
8529 }
8532 }
8537 /* The argument to invert_truthvalue must have Boolean type. */
8541 /* Note that the operand of this must be an int
8542 and its values must be 0 or 1.
8543 ("true" is a fixed value perhaps depending on the language,
8544 but we don't handle values other than 1 correctly yet.) */
8559 {
8567 }
8569 {
8573 }
8575 {
8579 {
8588 }
8589 }
8601 {
8609 }
8611 {
8615 }
8617 {
8621 {
8630 }
8631 }
8637 }
8640 /* If the operation was a conversion do _not_ mark a resulting constant
8641 with TREE_OVERFLOW if the original constant was not. These conversions
8642 have implementation defined behavior and retaining the TREE_OVERFLOW
8643 flag here would confuse later passes such as VRP. */
8644 tree
8646 {
8655 }
8657 /* Fold a binary expression of code CODE and type TYPE with operands
8658 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8659 Return the folded expression if folding is successful. Otherwise,
8660 return NULL_TREE. */
8662 static tree
8664 {
8671 else
8674 /* MIN (MAX (a, b), b) == b. */
8679 /* MIN (MAX (b, a), b) == b. */
8685 /* MIN (a, MAX (a, b)) == a. */
8691 /* MIN (a, MAX (b, a)) == a. */
8698 }
8700 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8701 by changing CODE to reduce the magnitude of constants involved in
8702 ARG0 of the comparison.
8703 Returns a canonicalized comparison tree if a simplification was
8704 possible, otherwise returns NULL_TREE.
8705 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8706 valid if signed overflow is undefined. */
8708 static tree
8712 {
8718 /* Match A +- CST code arg1 and CST code arg1. We can change the
8719 first form only if overflow is undefined. */
8721 /* In principle pointers also have undefined overflow behavior,
8722 but that causes problems elsewhere. */
8730 /* Identify the constant in arg0 and its sign. */
8733 else
8737 /* Overflowed constants and zero will cause problems. */
8742 /* See if we can reduce the magnitude of the constant in
8743 arg0 by changing the comparison code. */
8745 {
8746 /* CST <= arg1 -> CST-1 < arg1. */
8749 /* -CST < arg1 -> -CST-1 <= arg1. */
8752 /* CST > arg1 -> CST-1 >= arg1. */
8755 /* -CST >= arg1 -> -CST-1 > arg1. */
8758 else
8760 /* arg1 code' CST' might be more canonical. */
8762 }
8763 else
8764 {
8765 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8769 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8773 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8777 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8781 else
8784 }
8786 /* Now build the constant reduced in magnitude. But not if that
8787 would produce one outside of its types range. */
8795 /* We cannot swap the comparison here as that would cause us to
8796 endlessly recurse. */
8804 /* If swapping might yield to a more canonical form, do so. */
8807 else
8809 }
8811 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8812 overflow further. Try to decrease the magnitude of constants involved
8813 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8814 and put sole constants at the second argument position.
8815 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8817 static tree
8820 {
8821 tree t;
8826 /* Try canonicalization by simplifying arg0. */
8831 {
8835 }
8837 /* Try canonicalization by simplifying arg1 using the swapped
8838 comparison. */
8846 }
8848 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8849 space. This is used to avoid issuing overflow warnings for
8850 expressions like &p->x which can not wrap. */
8852 static bool
8854 {
8865 {
8868 }
8871 else
8872 {
8875 }
8890 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8891 array. */
8893 {
8894 HOST_WIDE_INT base_size;
8899 }
8902 }
8904 /* Subroutine of fold_binary. This routine performs all of the
8905 transformations that are common to the equality/inequality
8906 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8907 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8908 fold_binary should call fold_binary. Fold a comparison with
8909 tree code CODE and type TYPE with operands OP0 and OP1. Return
8910 the folded comparison or NULL_TREE. */
8912 static tree
8914 {
8927 /* If one arg is a real or integer constant, put it last. */
8931 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8938 {
8942 tree lhs;
8949 /* If the constant operation overflowed this can be
8950 simplified as a comparison against INT_MAX/INT_MIN. */
8953 {
8957 /* Get the sign of the constant on the lhs if the
8958 operation were VARIABLE + CONST1. */
8962 /* The sign of the constant determines if we overflowed
8963 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8964 Canonicalize to the INT_MIN overflow by swapping the comparison
8965 if necessary. */
8969 /* We now can look at the canonicalized case
8970 VARIABLE + 1 CODE2 INT_MIN
8971 and decide on the result. */
8980 }
8985 {
8987 "when changing X +- C1 cmp C2 to "
8989 WARN_STRICT_OVERFLOW_COMPARISON);
8991 }
8992 }
8994 /* For comparisons of pointers we can decompose it to a compile time
8995 comparison of the base objects and the offsets into the object.
8996 This requires at least one operand being an ADDR_EXPR or a
8997 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9003 {
9010 /* Get base and offset for the access. Strip ADDR_EXPR for
9011 get_inner_reference, but put it back by stripping INDIRECT_REF
9012 off the base object if possible. indirect_baseN will be true
9013 if baseN is not an address but refers to the object itself. */
9016 {
9022 else
9024 }
9026 {
9029 }
9033 {
9039 else
9041 }
9043 {
9046 }
9048 /* If we have equivalent bases we might be able to simplify. */
9051 {
9052 /* We can fold this expression to a constant if the non-constant
9053 offset parts are equal. */
9061 {
9068 "occur when comparing P +- C1 with "
9070 WARN_STRICT_OVERFLOW_CONDITIONAL);
9073 {
9087 }
9088 }
9089 /* We can simplify the comparison to a comparison of the variable
9090 offset parts if the constant offset parts are equal.
9091 Be careful to use signed size type here because otherwise we
9092 mess with array offsets in the wrong way. This is possible
9093 because pointer arithmetic is restricted to retain within an
9094 object and overflow on pointer differences is undefined as of
9095 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9099 {
9100 tree signed_size_type_node;
9103 /* By converting to signed size type we cover middle-end pointer
9104 arithmetic which operates on unsigned pointer types of size
9105 type size and ARRAY_REF offsets which are properly sign or
9106 zero extended from their type in case it is narrower than
9107 size type. */
9110 else
9114 else
9122 "occur when comparing P +- C1 with "
9124 WARN_STRICT_OVERFLOW_COMPARISON);
9127 }
9128 }
9129 /* For non-equal bases we can simplify if they are addresses
9130 of local binding decls or constants. */
9132 /* We know that !operand_equal_p (base0, base1, 0)
9133 because the if condition was false. But make
9134 sure two decls are not the same. */
9148 {
9153 }
9154 /* For equal offsets we can simplify to a comparison of the
9155 base addresses. */
9157 && (indirect_base0
9159 && (indirect_base1
9164 {
9170 }
9171 }
9173 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9174 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9175 the resulting offset is smaller in absolute value than the
9176 original one. */
9184 {
9189 tree cst;
9191 "occur when combining constants around "
9194 /* Put the constant on the side where it doesn't overflow and is
9195 of lower absolute value than before. */
9201 {
9204 variable1,
9207 }
9214 {
9219 variable2);
9220 }
9221 }
9223 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9224 signed arithmetic case. That form is created by the compiler
9225 often enough for folding it to be of value. One example is in
9226 computing loop trip counts after Operator Strength Reduction. */
9232 {
9241 "eliminating multiplication in comparison "
9243 WARN_STRICT_OVERFLOW_COMPARISON);
9245 /* If const1 is negative we swap the sense of the comparison. */
9250 }
9257 {
9265 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9270 /* (-a) CMP (-b) -> b CMP a */
9277 {
9278 REAL_VALUE_TYPE cst;
9281 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9288 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9289 /* a CMP (-0) -> a CMP 0 */
9294 /* x != NaN is always true, other ops are always false. */
9297 {
9300 }
9302 /* Fold comparisons against infinity. */
9305 {
9309 }
9310 }
9312 /* If this is a comparison of a real constant with a PLUS_EXPR
9313 or a MINUS_EXPR of a real constant, we can convert it into a
9314 comparison with a revised real constant as long as no overflow
9315 occurs when unsafe_math_optimizations are enabled. */
9327 /* Likewise, we can simplify a comparison of a real constant with
9328 a MINUS_EXPR whose first operand is also a real constant, i.e.
9329 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9330 floating-point types only if -fassociative-math is set. */
9341 /* Fold comparisons against built-in math functions. */
9343 && flag_unsafe_math_optimizations
9345 {
9349 {
9353 }
9354 }
9355 }
9359 {
9360 /* If we are widening one operand of an integer comparison,
9361 see if the other operand is similarly being widened. Perhaps we
9362 can do the comparison in the narrower type. */
9367 /* Or if we are changing signedness. */
9371 }
9373 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9374 constant, we can simplify it. */
9379 {
9383 }
9385 /* Simplify comparison of something with itself. (For IEEE
9386 floating-point, we can only do some of these simplifications.) */
9388 {
9390 {
9405 /* For NE, we can only do this simplification if integer
9406 or we don't honor IEEE floating point NaNs. */
9410 /* ... fall through ... */
9416 }
9417 }
9419 /* If we are comparing an expression that just has comparisons
9420 of two integer values, arithmetic expressions of those comparisons,
9421 and constants, we can simplify it. There are only three cases
9422 to check: the two values can either be equal, the first can be
9423 greater, or the second can be greater. Fold the expression for
9424 those three values. Since each value must be 0 or 1, we have
9425 eight possibilities, each of which corresponds to the constant 0
9426 or 1 or one of the six possible comparisons.
9428 This handles common cases like (a > b) == 0 but also handles
9429 expressions like ((x > y) - (y > x)) > 0, which supposedly
9430 occur in macroized code. */
9433 {
9438 /* Don't handle degenerate cases here; they should already
9439 have been handled anyway. */
9448 {
9452 /* We can't just pass T to eval_subst in case cval1 or cval2
9453 was the same as ARG1. */
9455 tree high_result
9459 arg1);
9460 tree equal_result
9464 arg1);
9465 tree low_result
9469 arg1);
9471 /* All three of these results should be 0 or 1. Confirm they are.
9472 Then use those values to select the proper code to use. */
9477 {
9478 /* Make a 3-bit mask with the high-order bit being the
9479 value for `>', the next for '=', and the low for '<'. */
9483 {
9485 /* Always false. */
9506 /* Always true. */
9508 }
9513 }
9514 }
9515 }
9517 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9518 into a single range test. */
9526 {
9530 }
9532 /* Fold ~X op ~Y as Y op X. */
9535 {
9540 }
9542 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9545 {
9551 }
9554 }
9557 /* Subroutine of fold_binary. Optimize complex multiplications of the
9558 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9559 argument EXPR represents the expression "z" of type TYPE. */
9561 static tree
9563 {
9568 {
9571 }
9573 {
9576 }
9577 else
9578 {
9582 }
9591 }
9594 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9595 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9596 guarantees that P and N have the same least significant log2(M) bits.
9597 N is not otherwise constrained. In particular, N is not normalized to
9598 0 <= N < M as is common. In general, the precise value of P is unknown.
9599 M is chosen as large as possible such that constant N can be determined.
9601 Returns M and sets *RESIDUE to N. */
9603 static unsigned HOST_WIDE_INT
9605 {
9612 {
9615 {
9617 tree offset;
9625 {
9628 else
9629 /* We don't handle more complicated offset expressions. */
9631 }
9632 }
9636 }
9638 {
9651 {
9654 }
9656 {
9659 {
9662 /* Compute the greatest power-of-2 divisor of op1. */
9666 /* If align is non-zero and less than *modulus, replace
9667 *modulus with align., If align is 0, then either op1 is 0
9668 or the greatest power-of-2 divisor of op1 doesn't fit in an
9669 unsigned HOST_WIDE_INT. In either case, no additional
9670 constraint is imposed. */
9675 }
9676 }
9677 }
9679 /* If we get here, we were unable to determine anything useful about the
9680 expression. */
9682 }
9685 /* Fold a binary expression of code CODE and type TYPE with operands
9686 OP0 and OP1. Return the folded expression if folding is
9687 successful. Otherwise, return NULL_TREE. */
9689 tree
9691 {
9705 /* Strip any conversions that don't change the mode. This is
9706 safe for every expression, except for a comparison expression
9707 because its signedness is derived from its operands. So, in
9708 the latter case, only strip conversions that don't change the
9709 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9710 preserved.
9712 Note that this is done as an internal manipulation within the
9713 constant folder, in order to find the simplest representation
9714 of the arguments so that their form can be studied. In any
9715 cases, the appropriate type conversions should be put back in
9716 the tree that will get out of the constant folder. */
9719 {
9722 }
9723 else
9724 {
9727 }
9729 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9730 constant but we can't do arithmetic on them. */
9737 {
9739 {
9740 /* Make sure type and arg0 have the same saturating flag. */
9744 }
9747 else
9751 {
9755 }
9756 }
9758 /* If this is a commutative operation, and ARG0 is a constant, move it
9759 to ARG1 to reduce the number of tests below. */
9764 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9766 First check for cases where an arithmetic operation is applied to a
9767 compound, conditional, or comparison operation. Push the arithmetic
9768 operation inside the compound or conditional to see if any folding
9769 can then be done. Convert comparison to conditional for this purpose.
9770 The also optimizes non-constant cases that used to be done in
9771 expand_expr.
9773 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9774 one of the operands is a comparison and the other is a comparison, a
9775 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9776 code below would make the expression more complex. Change it to a
9777 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9778 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9790 {
9794 boolean_type_node,
9802 }
9806 {
9812 op1));
9821 {
9827 }
9830 {
9836 }
9837 }
9840 {
9842 /* 0 +p index -> (type)index */
9846 /* PTR +p 0 -> PTR */
9850 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9857 /* index +p PTR -> PTR +p index */
9864 /* (PTR +p B) +p A -> PTR +p (B + A) */
9866 {
9867 tree inner;
9875 }
9877 /* PTR_CST +p CST -> CST1 */
9881 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9882 of the array. Loop optimizer sometimes produce this type of
9883 expressions. */
9885 {
9889 }
9894 /* A + (-B) -> A - B */
9899 /* (-A) + B -> B - A */
9907 {
9908 /* Convert ~A + 1 to -A. */
9914 /* ~X + X is -1. */
9917 {
9922 {
9925 }
9926 }
9928 /* X + ~X is -1. */
9931 {
9936 {
9939 }
9940 }
9942 /* X + (X / CST) * -CST is X % CST. */
9947 {
9955 }
9956 }
9958 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9959 same or one. Make sure type is not saturating.
9960 fold_plusminus_mult_expr will re-associate. */
9965 {
9969 }
9972 {
9976 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9977 with a constant, and the two constants have no bits in common,
9978 we should treat this as a BIT_IOR_EXPR since this may produce more
9979 simplifications. */
9987 {
9990 }
9992 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9993 (plus (plus (mult) (mult)) (foo)) so that we can
9994 take advantage of the factoring cases below. */
10001 {
10007 else
10029 parg1)));
10030 }
10031 }
10032 else
10033 {
10034 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10038 /* Likewise if the operands are reversed. */
10042 /* Convert X + -C into X - C. */
10045 {
10051 }
10053 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10054 to __complex__ ( x, y ). This is not the same for SNaNs or
10055 if signed zeros are involved. */
10059 {
10066 {
10070 {
10076 }
10078 {
10084 }
10085 }
10086 }
10094 /* Convert x+x into x*2.0. */
10100 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10101 We associate floats only if the user has specified
10102 -fassociative-math. */
10106 {
10111 {
10112 tree tree0;
10115 }
10116 }
10117 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10118 We associate floats only if the user has specified
10119 -fassociative-math. */
10123 {
10128 {
10129 tree tree0;
10132 }
10133 }
10134 }
10136 bit_rotate:
10137 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10138 is a rotate of A by C1 bits. */
10139 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10140 is a rotate of A by B bits. */
10141 {
10143 tree rtype;
10152 /* Only create rotates in complete modes. Other cases are not
10153 expanded properly. */
10155 {
10174 {
10182 TYPE_PRECISION
10187 ? LROTATE_EXPR
10190 }
10192 {
10200 TYPE_PRECISION
10205 ? LROTATE_EXPR
10208 }
10209 }
10210 }
10212 associate:
10213 /* In most languages, can't associate operations on floats through
10214 parentheses. Rather than remember where the parentheses were, we
10215 don't associate floats at all, unless the user has specified
10216 -fassociative-math.
10217 And, we need to make sure type is not saturating. */
10221 {
10226 /* Split both trees into variables, constants, and literals. Then
10227 associate each group together, the constants with literals,
10228 then the result with variables. This increases the chances of
10229 literals being recombined later and of generating relocatable
10230 expressions for the sum of a constant and literal. */
10235 /* With undefined overflow we can only associate constants
10236 with one variable. */
10240 {
10248 /* The only case we can still associate with two variables
10249 is if they are the same, modulo negation. */
10252 }
10254 /* Only do something if we found more than two objects. Otherwise,
10255 nothing has changed and we risk infinite recursion. */
10261 {
10262 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10271 /* Preserve the MINUS_EXPR if the negative part of the literal is
10272 greater than the positive part. Otherwise, the multiplicative
10273 folding code (i.e extract_muldiv) may be fooled in case
10274 unsigned constants are subtracted, like in the following
10275 example: ((X*2 + 4) - 8U)/2. */
10277 {
10281 {
10285 }
10286 else
10287 {
10291 }
10292 }
10294 {
10299 else
10300 {
10306 }
10307 }
10312 }
10313 }
10318 /* Pointer simplifications for subtraction, simple reassociations. */
10320 {
10321 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10324 {
10332 }
10333 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10335 {
10341 }
10342 }
10343 /* A - (-B) -> A + B */
10347 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10356 /* Convert -A - 1 to ~A. */
10364 /* Convert -1 - A to ~A. */
10370 /* X - (X / CST) * CST is X % CST. */
10383 {
10389 /* Fold A - (A & B) into ~B & A. */
10392 {
10394 {
10399 }
10401 {
10406 }
10407 }
10409 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10410 any power of 2 minus 1. */
10415 {
10421 {
10425 }
10426 }
10427 }
10429 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10433 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10434 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10435 (-ARG1 + ARG0) reduces to -ARG1. */
10439 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10440 __complex__ ( x, -y ). This is not the same for SNaNs or if
10441 signed zeros are involved. */
10445 {
10452 {
10456 {
10458 arg1r ? arg1r
10463 }
10465 {
10469 arg1i ? arg1i
10472 }
10473 }
10474 }
10476 /* Fold &x - &x. This can happen from &x.foo - &x.
10477 This is unsafe for certain floats even in non-IEEE formats.
10478 In IEEE, it is unsafe because it does wrong for NaNs.
10479 Also note that operand_equal_p is always false if an operand
10480 is volatile. */
10486 /* A - B -> A + (-B) if B is easily negatable. */
10489 /* Avoid this transformation if B is a positive REAL_CST. */
10497 /* Try folding difference of addresses. */
10498 {
10499 HOST_WIDE_INT diff;
10505 }
10507 /* Fold &a[i] - &a[j] to i-j. */
10512 {
10517 {
10525 }
10526 }
10534 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10535 same or one. Make sure type is not saturating.
10536 fold_plusminus_mult_expr will re-associate. */
10541 {
10545 }
10550 /* (-A) * (-B) -> A * B */
10561 {
10566 /* Transform x * -1 into -x. Make sure to do the negation
10567 on the original operand with conversions not stripped
10568 because we can only strip non-sign-changing conversions. */
10571 /* Transform x * -C into -x * C if x is easily negatable. */
10580 /* (a * (1 << b)) is (a << b) */
10590 /* (A + A) * C -> A * 2 * C */
10605 {
10608 "occur when simplifying "
10610 WARN_STRICT_OVERFLOW_MISC);
10612 }
10614 /* Optimize z * conj(z) for integer complex numbers. */
10621 }
10622 else
10623 {
10624 /* Maybe fold x * 0 to 0. The expressions aren't the same
10625 when x is NaN, since x * 0 is also NaN. Nor are they the
10626 same in modes with signed zeros, since multiplying a
10627 negative value by 0 gives -0, not +0. */
10632 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10637 /* Transform x * -1.0 into -x. */
10642 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10643 the result for floating point types due to rounding so it is applied
10644 only if -fassociative-math was specify. */
10649 {
10655 }
10657 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10659 {
10662 {
10665 }
10666 }
10668 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10669 This is not the same for NaNs or if signed zeros are
10670 involved. */
10676 {
10688 }
10690 /* Optimize z * conj(z) for floating point complex numbers.
10691 Guarded by flag_unsafe_math_optimizations as non-finite
10692 imaginary components don't produce scalar results. */
10703 {
10707 /* Optimizations of root(...)*root(...). */
10709 {
10714 /* Optimize sqrt(x)*sqrt(x) as x. */
10720 /* Optimize root(x)*root(y) as root(x*y). */
10724 }
10726 /* Optimize expN(x)*expN(y) as expN(x+y). */
10728 {
10734 }
10736 /* Optimizations of pow(...)*pow(...). */
10740 {
10746 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10748 {
10752 }
10754 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10756 {
10760 }
10761 }
10763 /* Optimize tan(x)*cos(x) as sin(x). */
10772 {
10777 }
10779 /* Optimize x*pow(x,c) as pow(x,c+1). */
10783 {
10789 {
10791 REAL_VALUE_TYPE c;
10792 tree arg;
10798 }
10799 }
10801 /* Optimize pow(x,c)*x as pow(x,c+1). */
10805 {
10811 {
10813 REAL_VALUE_TYPE c;
10814 tree arg;
10820 }
10821 }
10823 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10826 {
10830 {
10833 }
10834 }
10835 }
10836 }
10840 bit_ior:
10848 /* ~X | X is -1. */
10851 {
10855 }
10857 /* X | ~X is -1. */
10860 {
10864 }
10866 /* Canonicalize (X & C1) | C2. */
10870 {
10878 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10883 {
10887 }
10888 else
10889 {
10893 }
10895 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10900 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10901 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10902 mode which allows further optimizations. */
10912 {
10913 unsigned HOST_WIDE_INT mask
10917 {
10921 }
10922 }
10929 arg1);
10930 }
10932 /* (X & Y) | Y is (X, Y). */
10936 /* (X & Y) | X is (Y, X). */
10941 /* X | (X & Y) is (Y, X). */
10946 /* X | (Y & X) is (Y, X). */
10956 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10958 This results in more efficient code for machines without a NAND
10959 instruction. Combine will canonicalize to the first form
10960 which will allow use of NAND instructions provided by the
10961 backend if they exist. */
10964 {
10971 }
10973 /* See if this can be simplified into a rotate first. If that
10974 is unsuccessful continue in the association code. */
10985 /* ~X ^ X is -1. */
10988 {
10992 }
10994 /* X ^ ~X is -1. */
10997 {
11001 }
11003 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11004 with a constant, and the two constants have no bits in common,
11005 we should treat this as a BIT_IOR_EXPR since this may produce more
11006 simplifications. */
11014 {
11017 }
11019 /* (X | Y) ^ X -> Y & ~ X*/
11022 {
11025 arg1);
11029 }
11031 /* (Y | X) ^ X -> Y & ~ X*/
11034 {
11037 arg1);
11041 }
11043 /* X ^ (X | Y) -> Y & ~ X*/
11046 {
11049 arg0);
11053 }
11055 /* X ^ (Y | X) -> Y & ~ X*/
11058 {
11061 arg0);
11065 }
11067 /* Convert ~X ^ ~Y to X ^ Y. */
11074 /* Convert ~X ^ C to X ^ ~C. */
11081 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11088 /* Fold (X & Y) ^ Y as ~X & Y. */
11091 {
11096 }
11097 /* Fold (X & Y) ^ X as ~Y & X. */
11101 {
11106 }
11107 /* Fold X ^ (X & Y) as X & ~Y. */
11110 {
11115 }
11116 /* Fold X ^ (Y & X) as ~Y & X. */
11120 {
11125 }
11127 /* See if this can be simplified into a rotate first. If that
11128 is unsuccessful continue in the association code. */
11139 /* ~X & X is always zero. */
11144 /* X & ~X is always zero. */
11149 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11153 {
11161 }
11163 /* (X | Y) & Y is (X, Y). */
11167 /* (X | Y) & X is (Y, X). */
11172 /* X & (X | Y) is (Y, X). */
11177 /* X & (Y | X) is (Y, X). */
11183 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11187 {
11193 }
11194 /* Fold ~X & 1 as (X & 1) == 0. */
11197 {
11203 }
11205 /* Fold (X ^ Y) & Y as ~X & Y. */
11208 {
11213 }
11214 /* Fold (X ^ Y) & X as ~Y & X. */
11218 {
11223 }
11224 /* Fold X & (X ^ Y) as X & ~Y. */
11227 {
11232 }
11233 /* Fold X & (Y ^ X) as ~Y & X. */
11237 {
11242 }
11247 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11250 {
11251 unsigned int prec
11258 }
11260 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11262 This results in more efficient code for machines without a NOR
11263 instruction. Combine will canonicalize to the first form
11264 which will allow use of NOR instructions provided by the
11265 backend if they exist. */
11268 {
11275 }
11277 /* If arg0 is derived from the address of an object or function, we may
11278 be able to fold this expression using the object or function's
11279 alignment. */
11281 {
11287 /* This works because modulus is a power of 2. If this weren't the
11288 case, we'd have to replace it by its greatest power-of-2
11289 divisor: modulus & -modulus. */
11292 }
11294 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11295 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11296 if the new mask might be further optimized. */
11305 {
11307 unsigned HOST_WIDE_INT mask
11317 {
11320 /* See if more bits can be proven as zero because of
11321 zero extension. */
11324 {
11329 {
11331 /* See if we can shorten the right shift. */
11334 }
11335 }
11339 /* For arithmetic shift if sign bit could be set, zerobits
11340 can contain actually sign bits, so no transformation is
11341 possible, unless MASK masks them all away. In that
11342 case the shift needs to be converted into logical shift. */
11345 {
11348 else
11350 }
11351 }
11353 /* ((X << 16) & 0xff00) is (X, 0). */
11359 {
11362 /* Only do the transformation if NEWMASK is some integer
11363 mode's mask. */
11370 {
11371 tree newmaskt;
11374 {
11380 }
11381 else
11386 }
11387 }
11388 }
11393 /* Don't touch a floating-point divide by zero unless the mode
11394 of the constant can represent infinity. */
11400 /* Optimize A / A to 1.0 if we don't care about
11401 NaNs or Infinities. Skip the transformation
11402 for non-real operands. */
11407 {
11411 }
11413 /* The complex version of the above A / A optimization. */
11416 {
11420 {
11422 /* omit_two_operands will call fold_convert for us. */
11424 }
11425 }
11427 /* (-A) / (-B) -> A / B */
11437 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11442 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11447 /* If ARG1 is a constant, we can convert this to a multiply by the
11448 reciprocal. This does not have the same rounding properties,
11449 so only do this if -freciprocal-math. We can actually
11450 always safely do it if ARG1 is a power of two, but it's hard to
11451 tell if it is or not in a portable manner. */
11453 {
11458 /* Find the reciprocal if optimizing and the result is exact. */
11460 {
11461 REAL_VALUE_TYPE r;
11464 {
11468 }
11469 }
11470 }
11471 /* Convert A/B/C to A/(B*C). */
11478 /* Convert A/(B/C) to (A/B)*C. */
11486 /* Convert C1/(X*C2) into (C1/C2)/X. */
11491 {
11497 }
11500 {
11504 /* Optimize sin(x)/cos(x) as tan(x). */
11510 {
11515 }
11517 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11523 {
11527 {
11531 }
11532 }
11534 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11535 NaNs or Infinities. */
11539 {
11546 {
11551 }
11552 }
11554 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11555 NaNs or Infinities. */
11559 {
11566 {
11570 {
11574 tmp);
11575 }
11576 }
11577 }
11579 /* Optimize pow(x,c)/x as pow(x,c-1). */
11583 {
11589 {
11591 REAL_VALUE_TYPE c;
11592 tree arg;
11598 }
11599 }
11601 /* Optimize a/root(b/c) into a*root(c/b). */
11603 {
11607 {
11616 }
11617 }
11619 /* Optimize x/expN(y) into x*expN(-y). */
11621 {
11626 }
11628 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11632 {
11639 }
11640 }
11645 /* Simplify A / (B << N) where A and B are positive and B is
11646 a power of 2, to A >> (N + log2(B)). */
11651 {
11654 {
11661 WARN_STRICT_OVERFLOW_MISC);
11667 }
11668 }
11670 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11671 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11677 /* Fall thru */
11686 /* X / -1 is -X. */
11693 /* Convert -A / -B to A / B when the type is signed and overflow is
11694 undefined. */
11698 {
11701 "when distributing negation across "
11703 WARN_STRICT_OVERFLOW_MISC);
11707 }
11711 {
11714 "when distributing negation across "
11716 WARN_STRICT_OVERFLOW_MISC);
11720 }
11722 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11723 operation, EXACT_DIV_EXPR.
11725 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11726 At one time others generated faster code, it's not clear if they do
11727 after the last round to changes to the DIV code in expmed.c. */
11736 {
11740 WARN_STRICT_OVERFLOW_MISC);
11742 }
11750 /* X % 1 is always zero, but be sure to preserve any side
11751 effects in X. */
11755 /* X % 0, return X % 0 unchanged so that we can get the
11756 proper warnings and errors. */
11760 /* 0 % X is always zero, but be sure to preserve any side
11761 effects in X. Place this after checking for X == 0. */
11765 /* X % -1 is zero. */
11772 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11773 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11778 {
11780 /* Also optimize A % (C << N) where C is a power of 2,
11781 to A & ((C << N) - 1). */
11786 {
11791 "occur when simplifying "
11793 WARN_STRICT_OVERFLOW_MISC);
11797 }
11798 }
11800 /* X % -C is the same as X % C. */
11807 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11812 /* X % -Y is the same as X % Y. */
11823 {
11827 WARN_STRICT_OVERFLOW_MISC);
11829 }
11840 /* Optimize -1 >> x for arithmetic right shifts. */
11844 /* ... fall through ... */
11847 shift:
11853 /* Since negative shift count is not well-defined,
11854 don't try to compute it in the compiler. */
11858 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11863 {
11867 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11868 being well defined. */
11870 {
11876 else
11878 }
11882 }
11884 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11885 into x & ((unsigned)-1 >> c) for unsigned types. */
11893 {
11896 tree lshift;
11897 tree arg00;
11900 {
11907 }
11908 }
11910 /* Rewrite an LROTATE_EXPR by a constant into an
11911 RROTATE_EXPR by a new constant. */
11913 {
11918 }
11920 /* If we have a rotate of a bit operation with the rotate count and
11921 the second operand of the bit operation both constant,
11922 permute the two operations. */
11934 /* Two consecutive rotates adding up to the precision of the
11935 type can be ignored. */
11946 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11947 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11948 if the latter can be further optimized. */
11953 {
11956 arg1);
11959 arg1);
11963 }
11991 /* Note that the operands of this must be ints
11992 and their values must be 0 or 1.
11993 ("true" is a fixed value perhaps depending on the language.) */
11994 /* If first arg is constant zero, return it. */
11998 /* If either arg is constant true, drop it. */
12002 /* Preserve sequence points. */
12005 /* If second arg is constant zero, result is zero, but first arg
12006 must be evaluated. */
12009 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12010 case will be handled here. */
12014 /* !X && X is always false. */
12018 /* X && !X is always false. */
12023 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12024 means A >= Y && A != MAX, but in this case we know that
12025 A < X <= MAX. */
12029 {
12037 }
12039 truth_andor:
12040 /* We only do these simplifications if we are optimizing. */
12044 /* Check for things like (A || B) && (A || C). We can convert this
12045 to A || (B && C). Note that either operator can be any of the four
12046 truth and/or operations and the transformation will still be
12047 valid. Also note that we only care about order for the
12048 ANDIF and ORIF operators. If B contains side effects, this
12049 might change the truth-value of A. */
12056 {
12076 /* This case if tricky because we must either have commutative
12077 operators or else A10 must not have side-effects. */
12083 a01);
12084 }
12086 /* See if we can build a range comparison. */
12090 /* Check for the possibility of merging component references. If our
12091 lhs is another similar operation, try to merge its rhs with our
12092 rhs. Then try to merge our lhs and rhs. */
12104 /* Note that the operands of this must be ints
12105 and their values must be 0 or true.
12106 ("true" is a fixed value perhaps depending on the language.) */
12107 /* If first arg is constant true, return it. */
12111 /* If either arg is constant zero, drop it. */
12115 /* Preserve sequence points. */
12118 /* If second arg is constant true, result is true, but we must
12119 evaluate first arg. */
12122 /* Likewise for first arg, but note this only occurs here for
12123 TRUTH_OR_EXPR. */
12127 /* !X || X is always true. */
12131 /* X || !X is always true. */
12139 /* If the second arg is constant zero, drop it. */
12142 /* If the second arg is constant true, this is a logical inversion. */
12144 {
12145 /* Only call invert_truthvalue if operand is a truth value. */
12148 else
12151 }
12152 /* Identical arguments cancel to zero. */
12156 /* !X ^ X is always true. */
12161 /* X ^ !X is always true. */
12174 /* bool_var != 0 becomes bool_var. */
12179 /* bool_var == 1 becomes bool_var. */
12184 /* bool_var != 1 becomes !bool_var. */
12189 /* bool_var == 0 becomes !bool_var. */
12194 /* If this is an equality comparison of the address of two non-weak,
12195 unaliased symbols neither of which are extern (since we do not
12196 have access to attributes for externs), then we know the result. */
12209 {
12210 /* We know that we're looking at the address of two
12211 non-weak, unaliased, static _DECL nodes.
12213 It is both wasteful and incorrect to call operand_equal_p
12214 to compare the two ADDR_EXPR nodes. It is wasteful in that
12215 all we need to do is test pointer equality for the arguments
12216 to the two ADDR_EXPR nodes. It is incorrect to use
12217 operand_equal_p as that function is NOT equivalent to a
12218 C equality test. It can in fact return false for two
12219 objects which would test as equal using the C equality
12220 operator. */
12224 type);
12225 }
12227 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12228 a MINUS_EXPR of a constant, we can convert it into a comparison with
12229 a revised constant as long as no overflow occurs. */
12241 /* Similarly for a NEGATE_EXPR. */
12249 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12258 /* Transform comparisons of the form X +- C CMP X. */
12264 {
12271 else
12274 }
12276 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12277 for !=. Don't do this for ordered comparisons due to overflow. */
12283 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12288 /* If this is an EQ or NE comparison with zero and ARG0 is
12289 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12290 two operations, but the latter can be done in one less insn
12291 on machines that have only two-operand insns or on which a
12292 constant cannot be the first operand. */
12295 {
12300 {
12307 }
12310 {
12317 }
12318 }
12320 /* If this is an NE or EQ comparison of zero against the result of a
12321 signed MOD operation whose second operand is a power of 2, make
12322 the MOD operation unsigned since it is simpler and equivalent. */
12330 {
12340 }
12342 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12343 C1 is a valid shift constant, and C2 is a power of two, i.e.
12344 a single bit. */
12348 == INTEGER_CST
12351 {
12356 /* Check for a valid shift count. */
12359 {
12363 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12364 can be rewritten as (X & (C2 << C1)) != 0. */
12366 {
12370 }
12371 /* Otherwise, for signed (arithmetic) shifts,
12372 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12373 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12377 /* Otherwise, of unsigned (logical) shifts,
12378 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12379 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12380 else
12384 arg000);
12385 }
12386 }
12388 /* If this is an NE comparison of zero with an AND of one, remove the
12389 comparison since the AND will give the correct value. */
12396 /* If we have (A & C) == C where C is a power of 2, convert this into
12397 (A & C) != 0. Similarly for NE_EXPR. */
12403 integer_zero_node));
12405 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12406 bit, then fold the expression into A < 0 or A >= 0. */
12411 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12412 Similarly for NE_EXPR. */
12416 {
12425 }
12427 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12428 Similarly for NE_EXPR. */
12432 {
12439 }
12441 /* If this is a comparison of a field, we may be able to simplify it. */
12444 /* Handle the constant case even without -O
12445 to make sure the warnings are given. */
12447 {
12451 }
12453 /* Optimize comparisons of strlen vs zero to a compare of the
12454 first character of the string vs zero. To wit,
12455 strlen(ptr) == 0 => *ptr == 0
12456 strlen(ptr) != 0 => *ptr != 0
12457 Other cases should reduce to one of these two (or a constant)
12458 due to the return value of strlen being unsigned. */
12461 {
12469 {
12473 }
12474 }
12476 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12477 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12481 {
12488 {
12490 {
12493 }
12496 }
12497 }
12499 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12505 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12510 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12517 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12525 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12526 (X & C) == 0 when C is a single bit. */
12531 {
12537 }
12539 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12540 constant C is a power of two, i.e. a single bit. */
12547 {
12551 }
12553 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12554 when is C is a power of two, i.e. a single bit. */
12561 {
12567 }
12571 {
12574 }
12576 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12583 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12586 {
12598 arg01),
12606 arg01),
12614 arg00),
12622 arg00),
12624 }
12628 {
12635 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12636 operand_equal_p guarantees no side-effects so we don't need
12637 to use omit_one_operand on Z. */
12647 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12654 arg10);
12655 }
12657 /* Attempt to simplify equality/inequality comparisons of complex
12658 values. Only lower the comparison if the result is known or
12659 can be simplified to a single scalar comparison. */
12664 {
12669 {
12672 }
12673 else
12674 {
12677 }
12680 {
12683 }
12684 else
12685 {
12688 }
12692 {
12694 {
12699 }
12700 else
12701 {
12706 }
12707 }
12711 {
12713 {
12718 }
12719 else
12720 {
12725 }
12726 }
12727 }
12739 /* Transform comparisons of the form X +- C CMP X. */
12746 {
12753 else
12756 /* (X - c) > X becomes false. */
12760 {
12764 "occur when assuming that (X - c) > X "
12766 WARN_STRICT_OVERFLOW_ALL);
12768 }
12770 /* Likewise (X + c) < X becomes false. */
12774 {
12778 "occur when assuming that "
12780 WARN_STRICT_OVERFLOW_ALL);
12782 }
12784 /* Convert (X - c) <= X to true. */
12789 {
12793 "occur when assuming that "
12795 WARN_STRICT_OVERFLOW_ALL);
12797 }
12799 /* Convert (X + c) >= X to true. */
12804 {
12808 "occur when assuming that "
12810 WARN_STRICT_OVERFLOW_ALL);
12812 }
12815 {
12816 /* Convert X + c > X and X - c < X to true for integers. */
12820 {
12823 "not occur when assuming that "
12825 WARN_STRICT_OVERFLOW_ALL);
12827 }
12832 {
12835 "not occur when assuming that "
12837 WARN_STRICT_OVERFLOW_ALL);
12839 }
12841 /* Convert X + c <= X and X - c >= X to false for integers. */
12845 {
12848 "not occur when assuming that "
12850 WARN_STRICT_OVERFLOW_ALL);
12852 }
12857 {
12860 "not occur when assuming that "
12862 WARN_STRICT_OVERFLOW_ALL);
12864 }
12865 }
12866 }
12868 /* Comparisons with the highest or lowest possible integer of
12869 the specified precision will have known values. */
12870 {
12877 {
12878 HOST_WIDE_INT signed_max_hi;
12883 {
12890 {
12894 }
12895 else
12896 {
12900 }
12901 }
12902 else
12903 {
12912 {
12915 }
12916 else
12917 {
12920 }
12921 }
12926 {
12939 /* The GE_EXPR and LT_EXPR cases above are not normally
12940 reached because of previous transformations. */
12944 }
12946 == max_hi
12949 {
12955 arg1);
12961 arg1);
12964 }
12966 == min_hi
12969 {
12984 }
12986 == min_hi
12989 {
12994 arg1);
12999 arg1);
13002 }
13007 /* We will flip the signedness of the comparison operator
13008 associated with the mode of arg1, so the sign bit is
13009 specified by this mode. Check that arg1 is the signed
13010 max associated with this sign bit. */
13012 /* signed_type does not work on pointer types. */
13014 {
13015 /* The following case also applies to X < signed_max+1
13016 and X >= signed_max+1 because previous transformations. */
13018 {
13019 tree st;
13024 }
13025 }
13026 }
13027 }
13029 /* If we are comparing an ABS_EXPR with a constant, we can
13030 convert all the cases into explicit comparisons, but they may
13031 well not be faster than doing the ABS and one comparison.
13032 But ABS (X) <= C is a range comparison, which becomes a subtraction
13033 and a comparison, and is probably faster. */
13047 /* Convert ABS_EXPR<x> >= 0 to true. */
13054 {
13057 "when simplifying comparison of "
13059 WARN_STRICT_OVERFLOW_CONDITIONAL);
13061 }
13063 /* Convert ABS_EXPR<x> < 0 to false. */
13068 {
13071 "when simplifying comparison of "
13073 WARN_STRICT_OVERFLOW_CONDITIONAL);
13075 }
13077 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13078 and similarly for >= into !=. */
13093 return
13112 {
13116 }
13118 /* If the first operand is NaN, the result is constant. */
13122 {
13124 ? integer_zero_node
13127 }
13129 /* If the second operand is NaN, the result is constant. */
13133 {
13135 ? integer_zero_node
13138 }
13140 /* Simplify unordered comparison of something with itself. */
13146 && !flag_trapping_math
13150 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13151 {
13162 }
13167 /* When pedantic, a compound expression can be neither an lvalue
13168 nor an integer constant expression. */
13171 /* Don't let (0, 0) be null pointer constant. */
13185 /* An ASSERT_EXPR should never be passed to fold_binary. */
13191 }
13193 /* Callback for walk_tree, looking for LABEL_EXPR.
13194 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13195 Do not check the sub-tree of GOTO_EXPR. */
13197 static tree
13201 {
13203 {
13208 /* no break */
13211 }
13212 }
13214 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13215 accessible from outside the sub-tree. Returns NULL_TREE if no
13216 addressable label is found. */
13218 static bool
13220 {
13222 }
13224 /* Fold a ternary expression of code CODE and type TYPE with operands
13225 OP0, OP1, and OP2. Return the folded expression if folding is
13226 successful. Otherwise, return NULL_TREE. */
13228 tree
13230 {
13231 tree tem;
13238 /* Strip any conversions that don't change the mode. This is safe
13239 for every expression, except for a comparison expression because
13240 its signedness is derived from its operands. So, in the latter
13241 case, only strip conversions that don't change the signedness.
13243 Note that this is done as an internal manipulation within the
13244 constant folder, in order to find the simplest representation of
13245 the arguments so that their form can be studied. In any cases,
13246 the appropriate type conversions should be put back in the tree
13247 that will get out of the constant folder. */
13249 {
13252 }
13255 {
13258 }
13261 {
13265 {
13271 }
13275 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13276 so all simple results must be passed through pedantic_non_lvalue. */
13278 {
13281 /* Only optimize constant conditions when the selected branch
13282 has the same type as the COND_EXPR. This avoids optimizing
13283 away "c ? x : throw", where the throw has a void type.
13284 Avoid throwing away that operand which contains label. */
13291 }
13295 /* If we have A op B ? A : C, we may be able to convert this to a
13296 simpler expression, depending on the operation and the values
13297 of B and C. Signed zeros prevent all of these transformations,
13298 for reasons given above each one.
13300 Also try swapping the arguments and inverting the conditional. */
13305 {
13309 }
13313 op2,
13316 {
13319 {
13323 }
13324 }
13326 /* If the second operand is simpler than the third, swap them
13327 since that produces better jump optimization results. */
13330 {
13331 /* See if this can be inverted. If it can't, possibly because
13332 it was a floating-point inequality comparison, don't do
13333 anything. */
13337 }
13339 /* Convert A ? 1 : 0 to simply A. */
13342 /* If we try to convert OP0 to our type, the
13343 call to fold will try to move the conversion inside
13344 a COND, which will recurse. In that case, the COND_EXPR
13345 is probably the best choice, so leave it alone. */
13349 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13350 over COND_EXPR in cases such as floating point comparisons. */
13357 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13362 {
13363 /* sign_bit_p only checks ARG1 bits within A's precision.
13364 If <sign bit of A> has wider type than A, bits outside
13365 of A's precision in <sign bit of A> need to be checked.
13366 If they are all 0, this optimization needs to be done
13367 in unsigned A's type, if they are all 1 in signed A's type,
13368 otherwise this can't be done. */
13373 {
13375 HOST_WIDE_INT mask_hi;
13377 tree tem_type;
13385 {
13389 }
13390 else
13391 {
13395 }
13397 {
13401 }
13402 else
13408 {
13411 }
13414 {
13417 }
13418 else
13420 }
13427 arg1)));
13428 }
13430 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13431 already handled above. */
13436 {
13445 }
13447 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13448 is probably obsolete because the first operand should be a
13449 truth value (that's why we have the two cases above), but let's
13450 leave it in until we can confirm this for all front-ends. */
13461 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13467 arg1);
13469 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13473 {
13474 /* Only perform transformation if ARG0 is easily inverted. */
13479 arg1);
13480 }
13482 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13486 {
13487 /* Only perform transformation if ARG0 is easily inverted. */
13492 op2);
13493 }
13495 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13501 op2);
13506 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13507 of fold_ternary on them. */
13514 {
13523 {
13528 else
13529 {
13531 tree value;
13535 }
13540 else
13542 }
13543 }
13545 /* A bit-field-ref that referenced the full argument can be stripped. */
13556 }
13558 /* Perform constant folding and related simplification of EXPR.
13559 The related simplifications include x*1 => x, x*0 => 0, etc.,
13560 and application of the associative law.
13561 NOP_EXPR conversions may be removed freely (as long as we
13562 are careful not to change the type of the overall expression).
13563 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13564 but we can constant-fold them if they have constant operands. */
13566 #ifdef ENABLE_FOLD_CHECKING
13567 # define fold(x) fold_1 (x)
13569 static
13570 #endif
13571 tree
13573 {
13577 tree tem;
13579 /* Return right away if a constant. */
13583 /* CALL_EXPR-like objects with variable numbers of operands are
13584 treated specially. */
13586 {
13588 {
13591 }
13593 }
13596 {
13601 {
13619 }
13620 }
13623 {
13625 {
13632 {
13637 /* Find a matching index by means of a binary search. */
13639 {
13655 else
13657 }
13658 }
13661 }
13669 }
13671 #ifdef ENABLE_FOLD_CHECKING
13672 #undef fold
13678 /* When --enable-checking=fold, compute a digest of expr before
13679 and after actual fold call to see if fold did not accidentally
13680 change original expr. */
13682 tree
13684 {
13685 tree ret;
13688 htab_t ht;
13707 }
13709 void
13711 {
13714 htab_t ht;
13724 }
13726 static void
13728 {
13730 }
13732 static void
13734 {
13740 recursive_label:
13754 {
13755 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13759 }
13766 {
13767 /* Allow these fields to be modified. */
13768 tree tmp;
13776 {
13779 }
13780 }
13789 {
13792 {
13806 }
13810 {
13823 }
13840 {
13846 }
13851 {
13855 }
13866 {
13869 }
13879 }
13880 }
13882 /* Helper function for outputting the checksum of a tree T. When
13883 debugging with gdb, you can "define mynext" to be "next" followed
13884 by "call debug_fold_checksum (op0)", then just trace down till the
13885 outputs differ. */
13887 void
13889 {
13904 }
13906 #endif
13908 /* Fold a unary tree expression with code CODE of type TYPE with an
13909 operand OP0. Return a folded expression if successful. Otherwise,
13910 return a tree expression with code CODE of type TYPE with an
13911 operand OP0. */
13913 tree
13915 {
13916 tree tem;
13917 #ifdef ENABLE_FOLD_CHECKING
13920 htab_t ht;
13927 #endif
13933 #ifdef ENABLE_FOLD_CHECKING
13941 #endif
13943 }
13945 /* Fold a binary tree expression with code CODE of type TYPE with
13946 operands OP0 and OP1. Return a folded expression if successful.
13947 Otherwise, return a tree expression with code CODE of type TYPE
13948 with operands OP0 and OP1. */
13950 tree
13952 MEM_STAT_DECL)
13953 {
13954 tree tem;
13955 #ifdef ENABLE_FOLD_CHECKING
13961 htab_t ht;
13973 #endif
13979 #ifdef ENABLE_FOLD_CHECKING
13995 #endif
13997 }
13999 /* Fold a ternary tree expression with code CODE of type TYPE with
14000 operands OP0, OP1, and OP2. Return a folded expression if
14001 successful. Otherwise, return a tree expression with code CODE of
14002 type TYPE with operands OP0, OP1, and OP2. */
14004 tree
14006 MEM_STAT_DECL)
14007 {
14008 tree tem;
14009 #ifdef ENABLE_FOLD_CHECKING
14017 htab_t ht;
14034 #endif
14041 #ifdef ENABLE_FOLD_CHECKING
14065 #endif
14067 }
14069 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14070 arguments in ARGARRAY, and a null static chain.
14071 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14072 of type TYPE from the given operands as constructed by build_call_array. */
14074 tree
14076 {
14077 tree tem;
14078 #ifdef ENABLE_FOLD_CHECKING
14084 htab_t ht;
14098 #endif
14102 #ifdef ENABLE_FOLD_CHECKING
14119 #endif
14121 }
14123 /* Perform constant folding and related simplification of initializer
14124 expression EXPR. These behave identically to "fold_buildN" but ignore
14125 potential run-time traps and exceptions that fold must preserve. */
14127 #define START_FOLD_INIT \
14128 int saved_signaling_nans = flag_signaling_nans;\
14129 int saved_trapping_math = flag_trapping_math;\
14130 int saved_rounding_math = flag_rounding_math;\
14131 int saved_trapv = flag_trapv;\
14132 int saved_folding_initializer = folding_initializer;\
14133 flag_signaling_nans = 0;\
14134 flag_trapping_math = 0;\
14135 flag_rounding_math = 0;\
14136 flag_trapv = 0;\
14137 folding_initializer = 1;
14139 #define END_FOLD_INIT \
14140 flag_signaling_nans = saved_signaling_nans;\
14141 flag_trapping_math = saved_trapping_math;\
14142 flag_rounding_math = saved_rounding_math;\
14143 flag_trapv = saved_trapv;\
14144 folding_initializer = saved_folding_initializer;
14146 tree
14148 {
14149 tree result;
14150 START_FOLD_INIT;
14154 END_FOLD_INIT;
14156 }
14158 tree
14160 {
14161 tree result;
14162 START_FOLD_INIT;
14166 END_FOLD_INIT;
14168 }
14170 tree
14172 tree op2)
14173 {
14174 tree result;
14175 START_FOLD_INIT;
14179 END_FOLD_INIT;
14181 }
14183 tree
14186 {
14187 tree result;
14188 START_FOLD_INIT;
14192 END_FOLD_INIT;
14194 }
14196 #undef START_FOLD_INIT
14197 #undef END_FOLD_INIT
14199 /* Determine if first argument is a multiple of second argument. Return 0 if
14200 it is not, or we cannot easily determined it to be.
14202 An example of the sort of thing we care about (at this point; this routine
14203 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14204 fold cases do now) is discovering that
14206 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14208 is a multiple of
14210 SAVE_EXPR (J * 8)
14212 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14214 This code also handles discovering that
14216 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14218 is a multiple of 8 so we don't have to worry about dealing with a
14219 possible remainder.
14221 Note that we *look* inside a SAVE_EXPR only to determine how it was
14222 calculated; it is not safe for fold to do much of anything else with the
14223 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14224 at run time. For example, the latter example above *cannot* be implemented
14225 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14226 evaluation time of the original SAVE_EXPR is not necessarily the same at
14227 the time the new expression is evaluated. The only optimization of this
14228 sort that would be valid is changing
14230 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14232 divided by 8 to
14234 SAVE_EXPR (I) * SAVE_EXPR (J)
14236 (where the same SAVE_EXPR (J) is used in the original and the
14237 transformed version). */
14239 int
14241 {
14249 {
14251 /* Bitwise and provides a power of two multiple. If the mask is
14252 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14255 /* FALLTHRU */
14268 {
14272 /* const_binop may not detect overflow correctly,
14273 so check for it explicitly here. */
14279 size_one_node,
14283 }
14287 /* Can't handle conversions from non-integral or wider integral type. */
14293 /* .. fall through ... */
14310 }
14311 }
14313 /* Return true if CODE or TYPE is known to be non-negative. */
14315 static bool
14317 {
14320 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14321 have a signed:1 type (where the value is -1 and 0). */
14324 }
14326 /* Return true if (CODE OP0) is known to be non-negative. If the return
14327 value is based on the assumption that signed overflow is undefined,
14328 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14329 *STRICT_OVERFLOW_P. */
14331 bool
14334 {
14339 {
14341 /* We can't return 1 if flag_wrapv is set because
14342 ABS_EXPR<INT_MIN> = INT_MIN. */
14346 {
14349 }
14356 strict_overflow_p);
14359 {
14364 {
14367 strict_overflow_p);
14369 {
14373 strict_overflow_p);
14374 }
14375 }
14377 {
14380 strict_overflow_p);
14384 }
14385 }
14390 }
14392 /* We don't know sign of `t', so be conservative and return false. */
14394 }
14396 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14397 value is based on the assumption that signed overflow is undefined,
14398 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14399 *STRICT_OVERFLOW_P. */
14401 bool
14404 {
14409 {
14414 strict_overflow_p)
14416 strict_overflow_p));
14418 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14419 both unsigned and at least 2 bits shorter than the result. */
14423 {
14428 {
14432 }
14433 }
14438 {
14439 /* x * x for floating point x is always non-negative. */
14443 strict_overflow_p)
14445 strict_overflow_p));
14446 }
14448 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14449 both unsigned and their total bits is shorter than the result. */
14453 {
14472 {
14482 }
14483 }
14489 strict_overflow_p)
14491 strict_overflow_p));
14502 strict_overflow_p)
14504 strict_overflow_p));
14511 strict_overflow_p);
14514 }
14516 /* We don't know sign of `t', so be conservative and return false. */
14518 }
14520 /* Return true if T is known to be non-negative. If the return
14521 value is based on the assumption that signed overflow is undefined,
14522 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14523 *STRICT_OVERFLOW_P. */
14525 bool
14527 {
14532 {
14544 strict_overflow_p)
14546 strict_overflow_p));
14550 }
14551 /* We don't know sign of `t', so be conservative and return false. */
14553 }
14555 /* Return true if T is known to be non-negative. If the return
14556 value is based on the assumption that signed overflow is undefined,
14557 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14558 *STRICT_OVERFLOW_P. */
14560 bool
14563 {
14566 {
14584 /* Always true. */
14588 /* sqrt(-0.0) is -0.0. */
14592 strict_overflow_p);
14625 /* True if the 1st argument is nonnegative. */
14627 strict_overflow_p);
14630 /* True if the 1st OR 2nd arguments are nonnegative. */
14632 strict_overflow_p)
14634 strict_overflow_p)));
14637 /* True if the 1st AND 2nd arguments are nonnegative. */
14639 strict_overflow_p)
14641 strict_overflow_p)));
14644 /* True if the 2nd argument is nonnegative. */
14646 strict_overflow_p);
14649 /* True if the 1st argument is nonnegative or the second
14650 argument is an even integer. */
14655 strict_overflow_p);
14658 /* True if the 1st argument is nonnegative or the second
14659 argument is an even integer valued real. */
14661 {
14662 REAL_VALUE_TYPE c;
14663 HOST_WIDE_INT n;
14668 {
14669 REAL_VALUE_TYPE cint;
14674 }
14675 }
14677 strict_overflow_p);
14681 }
14683 type);
14684 }
14686 /* Return true if T is known to be non-negative. If the return
14687 value is based on the assumption that signed overflow is undefined,
14688 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14689 *STRICT_OVERFLOW_P. */
14691 bool
14693 {
14699 {
14701 {
14705 /* If the initializer is non-void, then it's a normal expression
14706 that will be assigned to the slot. */
14710 /* Otherwise, the initializer sets the slot in some way. One common
14711 way is an assignment statement at the end of the initializer. */
14713 {
14721 else
14723 }
14727 strict_overflow_p);
14730 }
14733 {
14739 arg0,
14740 arg1,
14741 strict_overflow_p);
14742 }
14746 strict_overflow_p);
14749 strict_overflow_p);
14752 strict_overflow_p);
14757 }
14759 /* We don't know sign of `t', so be conservative and return false. */
14761 }
14763 /* Return true if T is known to be non-negative. If the return
14764 value is based on the assumption that signed overflow is undefined,
14765 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14766 *STRICT_OVERFLOW_P. */
14768 bool
14770 {
14777 {
14784 strict_overflow_p);
14790 strict_overflow_p);
14799 }
14802 {
14810 strict_overflow_p);
14815 strict_overflow_p);
14830 }
14831 }
14833 /* Return true if `t' is known to be non-negative. Handle warnings
14834 about undefined signed overflow. */
14836 bool
14838 {
14845 "determining that expression is always "
14847 WARN_STRICT_OVERFLOW_MISC);
14849 }
14852 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14853 For floating point we further ensure that T is not denormal.
14854 Similar logic is present in nonzero_address in rtlanal.h.
14856 If the return value is based on the assumption that signed overflow
14857 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14858 change *STRICT_OVERFLOW_P. */
14860 bool
14863 {
14865 {
14868 strict_overflow_p);
14871 {
14877 strict_overflow_p));
14878 }
14883 strict_overflow_p);
14887 }
14890 }
14892 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14893 For floating point we further ensure that T is not denormal.
14894 Similar logic is present in nonzero_address in rtlanal.h.
14896 If the return value is based on the assumption that signed overflow
14897 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14898 change *STRICT_OVERFLOW_P. */
14900 bool
14902 tree type,
14903 tree op0,
14905 {
14908 {
14912 {
14913 /* With the presence of negative values it is hard
14914 to say something. */
14921 /* One of operands must be positive and the other non-negative. */
14922 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14923 overflows, on a twos-complement machine the sum of two
14924 nonnegative numbers can never be zero. */
14926 strict_overflow_p)
14928 strict_overflow_p));
14929 }
14934 {
14936 strict_overflow_p)
14938 strict_overflow_p))
14939 {
14942 }
14943 }
14952 {
14955 }
14962 {
14966 /* When both operands are nonzero, then MAX must be too. */
14968 strict_overflow_p))
14971 /* MAX where operand 0 is positive is positive. */
14973 strict_overflow_p);
14974 }
14975 /* MAX where operand 1 is positive is positive. */
14980 {
14984 }
14989 strict_overflow_p)
14991 strict_overflow_p));
14995 }
14998 }
15000 /* Return true when T is an address and is known to be nonzero.
15001 For floating point we further ensure that T is not denormal.
15002 Similar logic is present in nonzero_address in rtlanal.h.
15004 If the return value is based on the assumption that signed overflow
15005 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15006 change *STRICT_OVERFLOW_P. */
15008 bool
15010 {
15013 {
15018 {
15024 /* Weak declarations may link to NULL. */
15028 /* Constants are never weak. */
15033 }
15041 {
15045 }
15050 }
15052 }
15054 /* Return true when T is an address and is known to be nonzero.
15055 For floating point we further ensure that T is not denormal.
15056 Similar logic is present in nonzero_address in rtlanal.h.
15058 If the return value is based on the assumption that signed overflow
15059 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15060 change *STRICT_OVERFLOW_P. */
15062 bool
15064 {
15068 /* Doing something useful for floating point would need more work. */
15074 {
15077 strict_overflow_p);
15083 strict_overflow_p);
15091 }
15094 {
15097 strict_overflow_p);
15105 strict_overflow_p);
15122 strict_overflow_p);
15126 strict_overflow_p);
15133 }
15135 }
15137 /* Return true when T is an address and is known to be nonzero.
15138 Handle warnings about undefined signed overflow. */
15140 bool
15142 {
15149 "determining that expression is always "
15151 WARN_STRICT_OVERFLOW_MISC);
15153 }
15155 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15156 attempt to fold the expression to a constant without modifying TYPE,
15157 OP0 or OP1.
15159 If the expression could be simplified to a constant, then return
15160 the constant. If the expression would not be simplified to a
15161 constant, then return NULL_TREE. */
15163 tree
15165 {
15168 }
15170 /* Given the components of a unary expression CODE, TYPE and OP0,
15171 attempt to fold the expression to a constant without modifying
15172 TYPE or OP0.
15174 If the expression could be simplified to a constant, then return
15175 the constant. If the expression would not be simplified to a
15176 constant, then return NULL_TREE. */
15178 tree
15180 {
15183 }
15185 /* If EXP represents referencing an element in a constant string
15186 (either via pointer arithmetic or array indexing), return the
15187 tree representing the value accessed, otherwise return NULL. */
15189 tree
15191 {
15195 {
15197 tree index;
15198 tree string;
15202 else
15203 {
15207 /* Optimize the special-case of a zero lower bound.
15209 We convert the low_bound to sizetype to avoid some problems
15210 with constant folding. (E.g. suppose the lower bound is 1,
15211 and its mode is QI. Without the conversion,l (ARRAY
15212 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15213 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15218 }
15231 }
15233 }
15235 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15236 an integer constant, real, or fixed-point constant.
15238 TYPE is the type of the result. */
15240 static tree
15242 {
15246 {
15248 {
15250 HOST_WIDE_INT high;
15258 }
15265 {
15266 FIXED_VALUE_TYPE f;
15271 /* Propagate overflow flags. */
15273 {
15276 }
15280 }
15284 }
15287 }
15289 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15290 an integer constant or real constant.
15292 TYPE is the type of the result. */
15294 tree
15296 {
15300 {
15302 /* If the value is unsigned, then the absolute value is
15303 the same as the ordinary value. */
15306 /* Similarly, if the value is non-negative. */
15309 /* If the value is negative, then the absolute value is
15310 its negation. */
15311 else
15312 {
15314 HOST_WIDE_INT high;
15320 }
15326 else
15332 }
15335 }
15337 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15338 constant. TYPE is the type of the result. */
15340 static tree
15342 {
15352 }
15354 /* Given CODE, a relational operator, the target type, TYPE and two
15355 constant operands OP0 and OP1, return the result of the
15356 relational operation. If the result is not a compile time
15357 constant, then return NULL_TREE. */
15359 static tree
15361 {
15364 /* From here on, the only cases we handle are when the result is
15365 known to be a constant. */
15368 {
15372 /* Handle the cases where either operand is a NaN. */
15374 {
15376 {
15404 }
15407 }
15410 }
15413 {
15417 }
15419 /* Handle equality/inequality of complex constants. */
15421 {
15432 else
15434 }
15436 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15438 To compute GT, swap the arguments and do LT.
15439 To compute GE, do LT and invert the result.
15440 To compute LE, swap the arguments, do LT and invert the result.
15441 To compute NE, do EQ and invert the result.
15443 Therefore, the code below must handle only EQ and LT. */
15446 {
15451 }
15453 /* Note that it is safe to invert for real values here because we
15454 have already handled the one case that it matters. */
15458 {
15461 }
15463 /* Compute a result for LT or EQ if args permit;
15464 Otherwise return T. */
15466 {
15471 else
15473 }
15474 else
15480 }
15482 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15483 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15484 itself. */
15486 tree
15488 {
15489 /* If the expression does not have side effects then we don't have to wrap
15490 it with a cleanup point expression. */
15494 /* If the expression is a return, check to see if the expression inside the
15495 return has no side effects or the right hand side of the modify expression
15496 inside the return. If either don't have side effects set we don't need to
15497 wrap the expression in a cleanup point expression. Note we don't check the
15498 left hand side of the modify because it should always be a return decl. */
15500 {
15507 }
15510 }
15512 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15513 of an indirection through OP0, or NULL_TREE if no simplification is
15514 possible. */
15516 tree
15518 {
15520 tree subtype;
15528 {
15531 /* *&CONST_DECL -> to the value of the const decl. */
15534 /* *&p => p; make sure to handle *&"str"[cst] here. */
15536 {
15540 else
15542 }
15543 /* *(foo *)&fooarray => fooarray[0] */
15546 {
15552 }
15553 /* *(foo *)&complexfoo => __real__ complexfoo */
15557 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15560 {
15564 }
15565 }
15567 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15570 {
15573 tree op00type;
15580 {
15591 }
15592 }
15595 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15598 {
15601 tree op00type;
15608 {
15612 }
15613 }
15615 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15618 {
15619 tree type_domain;
15626 }
15629 }
15631 /* Builds an expression for an indirection through T, simplifying some
15632 cases. */
15634 tree
15636 {
15642 else
15644 }
15646 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15648 tree
15650 {
15655 else
15657 }
15659 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15660 whose result is ignored. The type of the returned tree need not be
15661 the same as the original expression. */
15663 tree
15665 {
15671 {
15682 else
15688 {
15704 }
15709 }
15710 }
15712 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15713 This can only be applied to objects of a sizetype. */
15715 tree
15717 {
15724 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15725 have to do anything. Only do this when we are not given a const,
15726 because in that case, this check is more expensive than just
15727 doing it. */
15729 {
15734 }
15736 /* If divisor is a power of two, simplify this to bit manipulation. */
15738 {
15740 {
15753 {
15754 high++;
15757 }
15761 }
15762 else
15763 {
15764 tree t;
15770 }
15771 }
15772 else
15773 {
15778 }
15781 }
15783 /* Likewise, but round down. */
15785 tree
15787 {
15794 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15795 have to do anything. Only do this when we are not given a const,
15796 because in that case, this check is more expensive than just
15797 doing it. */
15799 {
15804 }
15806 /* If divisor is a power of two, simplify this to bit manipulation. */
15808 {
15809 tree t;
15813 }
15814 else
15815 {
15820 }
15823 }
15825 /* Returns the pointer to the base of the object addressed by EXP and
15826 extracts the information about the offset of the access, storing it
15827 to PBITPOS and POFFSET. */
15829 static tree
15832 {
15833 tree core;
15836 HOST_WIDE_INT bitsize;
15839 {
15844 }
15845 else
15846 {
15850 }
15853 }
15855 /* Returns true if addresses of E1 and E2 differ by a constant, false
15856 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15858 bool
15860 {
15874 {
15884 }
15886 {
15887 /* If only one of the offsets is non-constant, the difference cannot
15888 be a constant. */
15890 }
15891 else
15896 }
15898 /* Simplify the floating point expression EXP when the sign of the
15899 result is not significant. Return NULL_TREE if no simplification
15900 is possible. */
15902 tree
15904 {
15908 {
15943 {
15946 {
15948 /* Strip copysign function call, return the 1st argument. */
15954 /* Strip sign ops from the argument of "odd" math functions. */
15956 {
15960 }
15962 }
15963 }
15968 }
15970 }