| blob | 7bf48060cd145f53e272005239b6606b98e505a1 |
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 };
147 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
148 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
149 and SUM1. Then this yields nonzero if overflow occurred during the
150 addition.
152 Overflow occurs if A and B have the same sign, but A and SUM differ in
153 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
154 sign. */
155 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
156 \f
157 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
158 We do that by representing the two-word integer in 4 words, with only
159 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
160 number. The value of the word is LOWPART + HIGHPART * BASE. */
162 #define LOWPART(x) \
163 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
164 #define HIGHPART(x) \
165 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
166 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
168 /* Unpack a two-word integer into 4 words.
169 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
170 WORDS points to the array of HOST_WIDE_INTs. */
172 static void
174 {
179 }
181 /* Pack an array of 4 words into a two-word integer.
182 WORDS points to the array of words.
183 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
185 static void
188 {
191 }
192 \f
193 /* Force the double-word integer L1, H1 to be within the range of the
194 integer type TYPE. Stores the properly truncated and sign-extended
195 double-word integer in *LV, *HV. Returns true if the operation
196 overflows, that is, argument and result are different. */
198 int
201 {
210 else
213 /* Size types *are* sign extended. */
218 /* First clear all bits that are beyond the type's precision. */
220 ;
223 else
224 {
228 }
230 /* Then do sign extension if necessary. */
236 {
237 /* Sign extend top half? */
241 }
243 {
246 }
247 else
248 {
249 /* Sign extend bottom half? */
251 {
254 }
255 }
260 /* If the value didn't fit, signal overflow. */
262 }
264 /* We force the double-int HIGH:LOW to the range of the type TYPE by
265 sign or zero extending it.
266 OVERFLOWABLE indicates if we are interested
267 in overflow of the value, when >0 we are only interested in signed
268 overflow, for <0 we are interested in any overflow. OVERFLOWED
269 indicates whether overflow has already occurred. CONST_OVERFLOWED
270 indicates whether constant overflow has already occurred. We force
271 T's value to be within range of T's type (by setting to 0 or 1 all
272 the bits outside the type's range). We set TREE_OVERFLOWED if,
273 OVERFLOWED is nonzero,
274 or OVERFLOWABLE is >0 and signed overflow occurs
275 or OVERFLOWABLE is <0 and any overflow occurs
276 We return a new tree node for the extended double-int. The node
277 is shared if no overflow flags are set. */
279 tree
283 {
287 /* Size types *are* sign extended. */
294 /* If we need to set overflow flags, return a new unshared node. */
296 {
300 {
307 }
308 }
310 /* Else build a shared node. */
312 }
313 \f
314 /* Add two doubleword integers with doubleword result.
315 Return nonzero if the operation overflows according to UNSIGNED_P.
316 Each argument is given as two `HOST_WIDE_INT' pieces.
317 One argument is L1 and H1; the other, L2 and H2.
318 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
320 int
325 {
327 HOST_WIDE_INT h;
341 else
343 }
345 /* Negate a doubleword integer with doubleword result.
346 Return nonzero if the operation overflows, assuming it's signed.
347 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
348 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
350 int
353 {
355 {
359 }
360 else
361 {
365 }
366 }
367 \f
368 /* Multiply two doubleword integers with doubleword result.
369 Return nonzero if the operation overflows according to UNSIGNED_P.
370 Each argument is given as two `HOST_WIDE_INT' pieces.
371 One argument is L1 and H1; the other, L2 and H2.
372 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
374 int
379 {
394 {
397 {
399 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
401 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
405 }
407 }
412 /* Unsigned overflow is immediate. */
416 /* Check for signed overflow by calculating the signed representation of the
417 top half of the result; it should agree with the low half's sign bit. */
419 {
422 }
424 {
427 }
429 }
430 \f
431 /* Shift the doubleword integer in L1, H1 left by COUNT places
432 keeping only PREC bits of result.
433 Shift right if COUNT is negative.
434 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
435 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
437 void
441 {
445 {
448 }
454 {
455 /* Shifting by the host word size is undefined according to the
456 ANSI standard, so we must handle this as a special case. */
459 }
461 {
464 }
465 else
466 {
470 }
472 /* Sign extend all bits that are beyond the precision. */
480 ;
482 {
485 }
486 else
487 {
491 }
492 }
494 /* Shift the doubleword integer in L1, H1 right by COUNT places
495 keeping only PREC bits of result. COUNT must be positive.
496 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
497 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
499 void
504 {
507 signmask = (arith
515 {
516 /* Shifting by the host word size is undefined according to the
517 ANSI standard, so we must handle this as a special case. */
520 }
522 {
525 }
526 else
527 {
531 }
533 /* Zero / sign extend all bits that are beyond the precision. */
536 {
539 }
541 ;
543 {
546 }
547 else
548 {
552 }
553 }
554 \f
555 /* Rotate the doubleword integer in L1, H1 left by COUNT places
556 keeping only PREC bits of result.
557 Rotate right if COUNT is negative.
558 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
560 void
564 {
576 }
578 /* Rotate the doubleword integer in L1, H1 left by COUNT places
579 keeping only PREC bits of result. COUNT must be positive.
580 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
582 void
586 {
598 }
599 \f
600 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
601 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
602 CODE is a tree code for a kind of division, one of
603 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
604 or EXACT_DIV_EXPR
605 It controls how the quotient is rounded to an integer.
606 Return nonzero if the operation overflows.
607 UNS nonzero says do unsigned division. */
609 int
612 HOST_WIDE_INT hnum_orig,
614 HOST_WIDE_INT hden_orig,
618 {
634 /* Calculate quotient sign and convert operands to unsigned. */
636 {
638 {
640 /* (minimum integer) / (-1) is the only overflow case. */
644 }
646 {
649 }
650 }
655 /* This unsigned division rounds toward zero. */
658 }
662 /* hden != 0 already checked. */
667 }
677 /* Special code for when the divisor < BASE. */
679 {
680 /* hnum != 0 already checked. */
682 {
686 }
687 }
688 else
689 {
690 /* Full double precision division,
691 with thanks to Don Knuth's "Seminumerical Algorithms". */
695 /* Find the highest nonzero divisor digit. */
698 {
701 }
703 /* Insure that the first digit of the divisor is at least BASE/2.
704 This is required by the quotient digit estimation algorithm. */
711 {
715 }
720 {
725 }
726 }
730 /* Main loop */
732 {
733 /* Guess the next quotient digit, quo_est, by dividing the first
734 two remaining dividend digits by the high order quotient digit.
735 quo_est is never low and is at most 2 high. */
742 else
745 /* Refine quo_est so it's usually correct, and at most one high. */
750 quo_est--;
752 /* Try QUO_EST as the quotient digit, by multiplying the
753 divisor by QUO_EST and subtracting from the remaining dividend.
754 Keep in mind that QUO_EST is the I - 1st digit. */
758 {
764 }
766 /* If quo_est was high by one, then num[i] went negative and
767 we need to correct things. */
769 {
770 quo_est--;
773 {
777 }
780 }
782 /* Store the quotient digit. */
784 }
785 }
789 finish_up:
790 /* If result is negative, make it so. */
794 /* Compute trial remainder: rem = num - (quo * den) */
800 {
809 {
810 /* quo = quo - 1; */
813 }
814 else
821 {
824 }
825 else
831 {
837 /* Get absolute values. */
843 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
852 {
854 /* quo = quo - 1; */
857 else
858 /* quo = quo + 1; */
861 }
862 else
864 }
869 }
871 /* Compute true remainder: rem = num - (quo * den) */
876 }
878 /* If ARG2 divides ARG1 with zero remainder, carries out the division
879 of type CODE and returns the quotient.
880 Otherwise returns NULL_TREE. */
882 tree
884 {
894 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
895 &obj[some_exotic_number]. */
897 {
901 type);
902 }
903 else
914 }
915 \f
916 /* This is nonzero if we should defer warnings about undefined
917 overflow. This facility exists because these warnings are a
918 special case. The code to estimate loop iterations does not want
919 to issue any warnings, since it works with expressions which do not
920 occur in user code. Various bits of cleanup code call fold(), but
921 only use the result if it has certain characteristics (e.g., is a
922 constant); that code only wants to issue a warning if the result is
923 used. */
927 /* If a warning about undefined overflow is deferred, this is the
928 warning. Note that this may cause us to turn two warnings into
929 one, but that is fine since it is sufficient to only give one
930 warning per expression. */
934 /* If a warning about undefined overflow is deferred, this is the
935 level at which the warning should be emitted. */
939 /* Start deferring overflow warnings. We could use a stack here to
940 permit nested calls, but at present it is not necessary. */
942 void
944 {
946 }
948 /* Stop deferring overflow warnings. If there is a pending warning,
949 and ISSUE is true, then issue the warning if appropriate. STMT is
950 the statement with which the warning should be associated (used for
951 location information); STMT may be NULL. CODE is the level of the
952 warning--a warn_strict_overflow_code value. This function will use
953 the smaller of CODE and the deferred code when deciding whether to
954 issue the warning. CODE may be zero to mean to always use the
955 deferred code. */
957 void
959 {
961 location_t locus;
966 {
972 }
983 /* Use the smallest code level when deciding to issue the
984 warning. */
993 else
996 }
998 /* Stop deferring overflow warnings, ignoring any deferred
999 warnings. */
1001 void
1003 {
1005 }
1007 /* Whether we are deferring overflow warnings. */
1009 bool
1011 {
1013 }
1015 /* This is called when we fold something based on the fact that signed
1016 overflow is undefined. */
1018 static void
1020 {
1022 {
1025 {
1028 }
1029 }
1032 }
1033 \f
1034 /* Return true if the built-in mathematical function specified by CODE
1035 is odd, i.e. -f(x) == f(-x). */
1037 static bool
1039 {
1041 {
1075 }
1077 }
1079 /* Check whether we may negate an integer constant T without causing
1080 overflow. */
1082 bool
1084 {
1087 tree type;
1097 {
1102 }
1103 else
1108 }
1110 /* Determine whether an expression T can be cheaply negated using
1111 the function negate_expr without introducing undefined overflow. */
1113 static bool
1115 {
1116 tree type;
1125 {
1156 /* -(A + B) -> (-B) - A. */
1161 /* -(A + B) -> (-A) - B. */
1166 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1177 /* Fall through. */
1190 /* In general we can't negate A / B, because if A is INT_MIN and
1191 B is 1, we may turn this into INT_MIN / -1 which is undefined
1192 and actually traps on some architectures. */
1198 CASE_CONVERT:
1199 /* Negate -((double)float) as (double)(-float). */
1201 {
1205 }
1209 /* Negate -f(x) as f(-x). */
1215 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1217 {
1223 }
1228 }
1230 }
1232 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1233 simplification is possible.
1234 If negate_expr_p would return true for T, NULL_TREE will never be
1235 returned. */
1237 static tree
1239 {
1241 tree tem;
1244 {
1245 /* Convert - (~A) to A + 1. */
1261 /* Two's complement FP formats, such as c4x, may overflow. */
1271 {
1280 }
1304 {
1305 /* -(A + B) -> (-B) - A. */
1309 {
1313 }
1315 /* -(A + B) -> (-A) - B. */
1317 {
1321 }
1322 }
1327 /* - (A - B) -> B - A */
1340 /* Fall through. */
1344 {
1353 }
1361 /* In general we can't negate A / B, because if A is INT_MIN and
1362 B is 1, we may turn this into INT_MIN / -1 which is undefined
1363 and actually traps on some architectures. */
1365 {
1374 }
1377 CASE_CONVERT:
1378 /* Convert -((double)float) into (double)(-float). */
1380 {
1384 }
1388 /* Negate -f(x) as f(-x). */
1391 {
1397 }
1401 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1403 {
1408 {
1415 }
1416 }
1421 }
1424 }
1426 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1427 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1428 return NULL_TREE. */
1430 static tree
1432 {
1445 }
1446 \f
1447 /* Split a tree IN into a constant, literal and variable parts that could be
1448 combined with CODE to make IN. "constant" means an expression with
1449 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1450 commutative arithmetic operation. Store the constant part into *CONP,
1451 the literal in *LITP and return the variable part. If a part isn't
1452 present, set it to null. If the tree does not decompose in this way,
1453 return the entire tree as the variable part and the other parts as null.
1455 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1456 case, we negate an operand that was subtracted. Except if it is a
1457 literal for which we use *MINUS_LITP instead.
1459 If NEGATE_P is true, we are negating all of IN, again except a literal
1460 for which we use *MINUS_LITP instead.
1462 If IN is itself a literal or constant, return it as appropriate.
1464 Note that we do not guarantee that any of the three values will be the
1465 same type as IN, but they will have the same signedness and mode. */
1467 static tree
1470 {
1477 /* Strip any conversions that don't change the machine mode or signedness. */
1486 /* We can associate addition and subtraction together (even
1487 though the C standard doesn't say so) for integers because
1488 the value is not affected. For reals, the value might be
1489 affected, so we can't. */
1492 {
1498 /* First see if either of the operands is a literal, then a constant. */
1511 /* If we haven't dealt with either operand, this is not a case we can
1512 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1517 else
1520 /* Now do any needed negations. */
1527 }
1530 else
1534 {
1541 }
1544 }
1546 /* Re-associate trees split by the above function. T1 and T2 are either
1547 expressions to associate or null. Return the new expression, if any. If
1548 we build an operation, do it in TYPE and with CODE. */
1550 static tree
1552 {
1558 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1559 try to fold this since we will have infinite recursion. But do
1560 deal with any NEGATE_EXPRs. */
1564 {
1566 {
1575 }
1577 {
1580 }
1584 }
1588 }
1589 \f
1590 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1591 for use in int_const_binop, size_binop and size_diffop. */
1593 static bool
1595 {
1602 {
1611 }
1616 }
1619 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1620 to produce a new constant in *LOWP, *HIP. Return -1 if we don't know how
1621 to evaluate CODE at compile-time otherwise return 1 if the
1622 operation overflowed and 0 if not. */
1624 int
1627 {
1631 HOST_WIDE_INT hi;
1633 HOST_WIDE_INT garbageh;
1644 {
1660 /* It's unclear from the C standard whether shifts can overflow.
1661 The following code ignores overflow; perhaps a C standard
1662 interpretation ruling is needed. */
1688 else
1701 /* This is a shortcut for a common special case. */
1706 {
1712 }
1714 /* ... fall through ... */
1720 {
1723 }
1726 {
1729 }
1736 /* This is a shortcut for a common special case. */
1741 {
1746 }
1748 /* ... fall through ... */
1766 else
1772 else
1778 }
1784 }
1786 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1787 to produce a new constant. Return NULL_TREE if we don't know how
1788 to evaluate CODE at compile-time.
1790 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1792 tree
1795 {
1797 HOST_WIDE_INT hi;
1798 tree t;
1801 int is_sizetype
1810 {
1813 /* Propagate overflow flags ourselves. */
1816 {
1819 }
1820 }
1821 else
1827 }
1829 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1830 constant. We assume ARG1 and ARG2 have the same data type, or at least
1831 are the same kind of constant and the same machine mode. Return zero if
1832 combining the constants is not allowed in the current operating mode.
1834 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1836 static tree
1838 {
1839 /* Sanity check for the recursive cases. */
1850 {
1852 REAL_VALUE_TYPE d1;
1853 REAL_VALUE_TYPE d2;
1854 REAL_VALUE_TYPE value;
1855 REAL_VALUE_TYPE result;
1859 /* The following codes are handled by real_arithmetic. */
1861 {
1872 }
1880 /* Don't perform operation if we honor signaling NaNs and
1881 either operand is a NaN. */
1886 /* Don't perform operation if it would raise a division
1887 by zero exception. */
1893 /* If either operand is a NaN, just return it. Otherwise, set up
1894 for floating-point trap; we return an overflow. */
1903 /* Don't constant fold this floating point operation if
1904 the result has overflowed and flag_trapping_math. */
1912 /* Don't constant fold this floating point operation if the
1913 result may dependent upon the run-time rounding mode and
1914 flag_rounding_math is set, or if GCC's software emulation
1915 is unable to accurately represent the result. */
1925 }
1928 {
1929 FIXED_VALUE_TYPE f1;
1930 FIXED_VALUE_TYPE f2;
1931 FIXED_VALUE_TYPE result;
1936 /* The following codes are handled by fixed_arithmetic. */
1938 {
1955 }
1962 /* Propagate overflow flags. */
1966 }
1969 {
1978 {
1989 notrunc);
1993 notrunc);
1997 {
1998 tree magsquared
2002 notrunc);
2003 tree t1
2007 notrunc);
2008 tree t2
2012 notrunc);
2019 }
2024 }
2028 }
2031 {
2043 {
2046 /* The trailing elements can be empty and should be treated as 0 */
2049 else
2050 {
2053 }
2057 else
2058 {
2061 }
2065 /* It is possible that const_binop cannot handle the given
2066 code and return NULL_TREE */
2071 }
2073 }
2075 }
2077 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2078 indicates which particular sizetype to create. */
2080 tree
2082 {
2084 }
2085 \f
2086 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2087 is a tree code. The type of the result is taken from the operands.
2088 Both must be equivalent integer types, ala int_binop_types_match_p.
2089 If the operands are constant, so is the result. */
2091 tree
2093 {
2102 /* Handle the special case of two integer constants faster. */
2104 {
2105 /* And some specific cases even faster than that. */
2107 {
2112 }
2114 {
2117 }
2119 {
2122 }
2124 /* Handle general case of two integer constants. */
2126 }
2129 }
2131 /* Given two values, either both of sizetype or both of bitsizetype,
2132 compute the difference between the two values. Return the value
2133 in signed type corresponding to the type of the operands. */
2135 tree
2137 {
2139 tree ctype;
2144 /* If the type is already signed, just do the simple thing. */
2152 else
2155 /* If either operand is not a constant, do the conversions to the signed
2156 type and subtract. The hardware will do the right thing with any
2157 overflow in the subtraction. */
2162 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2163 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2164 overflow) and negate (which can't either). Special-case a result
2165 of zero while we're here. */
2170 else
2174 }
2175 \f
2176 /* A subroutine of fold_convert_const handling conversions of an
2177 INTEGER_CST to another integer type. */
2179 static tree
2181 {
2182 tree t;
2184 /* Given an integer constant, make new constant with new type,
2185 appropriately sign-extended or truncated. */
2188 /* Don't set the overflow when
2189 converting from a pointer, */
2191 /* or to a sizetype with same signedness
2192 and the precision is unchanged.
2193 ??? sizetype is always sign-extended,
2194 but its signedness depends on the
2195 frontend. Thus we see spurious overflows
2196 here if we do not check this. */
2211 }
2213 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2214 to an integer type. */
2216 static tree
2218 {
2220 tree t;
2222 /* The following code implements the floating point to integer
2223 conversion rules required by the Java Language Specification,
2224 that IEEE NaNs are mapped to zero and values that overflow
2225 the target precision saturate, i.e. values greater than
2226 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2227 are mapped to INT_MIN. These semantics are allowed by the
2228 C and C++ standards that simply state that the behavior of
2229 FP-to-integer conversion is unspecified upon overflow. */
2232 REAL_VALUE_TYPE r;
2236 {
2243 }
2245 /* If R is NaN, return zero and show we have an overflow. */
2247 {
2251 }
2253 /* See if R is less than the lower bound or greater than the
2254 upper bound. */
2257 {
2261 {
2265 }
2266 }
2269 {
2272 {
2275 {
2279 }
2280 }
2281 }
2289 }
2291 /* A subroutine of fold_convert_const handling conversions of a
2292 FIXED_CST to an integer type. */
2294 static tree
2296 {
2297 tree t;
2301 /* Right shift FIXED_CST to temp by fbit. */
2305 {
2310 /* Left shift temp to temp_trunc by fbit. */
2315 }
2316 else
2317 {
2322 }
2324 /* If FIXED_CST is negative, we need to round the value toward 0.
2325 By checking if the fractional bits are not zero to add 1 to temp. */
2328 {
2329 double_int one;
2333 }
2335 /* Given a fixed-point constant, make new constant with new type,
2336 appropriately sign-extended or truncated. */
2344 }
2346 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2347 to another floating point type. */
2349 static tree
2351 {
2352 REAL_VALUE_TYPE value;
2353 tree t;
2358 /* If converting an infinity or NAN to a representation that doesn't
2359 have one, set the overflow bit so that we can produce some kind of
2360 error message at the appropriate point if necessary. It's not the
2361 most user-friendly message, but it's better than nothing. */
2368 /* Regular overflow, conversion produced an infinity in a mode that
2369 can't represent them. */
2374 else
2377 }
2379 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2380 to a floating point type. */
2382 static tree
2384 {
2385 REAL_VALUE_TYPE value;
2386 tree t;
2393 }
2395 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2396 to another fixed-point type. */
2398 static tree
2400 {
2401 FIXED_VALUE_TYPE value;
2402 tree t;
2409 /* Propagate overflow flags. */
2413 }
2415 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2416 to a fixed-point type. */
2418 static tree
2420 {
2421 FIXED_VALUE_TYPE value;
2422 tree t;
2431 /* Propagate overflow flags. */
2435 }
2437 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2438 to a fixed-point type. */
2440 static tree
2442 {
2443 FIXED_VALUE_TYPE value;
2444 tree t;
2452 /* Propagate overflow flags. */
2456 }
2458 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2459 type TYPE. If no simplification can be done return NULL_TREE. */
2461 static tree
2463 {
2469 {
2476 }
2478 {
2485 }
2487 {
2494 }
2496 }
2498 /* Construct a vector of zero elements of vector type TYPE. */
2500 static tree
2502 {
2513 }
2515 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2517 bool
2519 {
2534 {
2553 }
2554 }
2556 /* Convert expression ARG to type TYPE. Used by the middle-end for
2557 simple conversions in preference to calling the front-end's convert. */
2559 tree
2561 {
2563 tree tem;
2577 {
2582 {
2586 }
2591 {
2594 }
2601 {
2605 }
2607 {
2611 }
2613 {
2617 }
2620 {
2638 }
2643 {
2647 }
2650 {
2664 }
2668 {
2677 integer_zero_node));
2679 {
2683 {
2687 }
2695 }
2699 }
2717 }
2718 }
2719 \f
2720 /* Return false if expr can be assumed not to be an lvalue, true
2721 otherwise. */
2723 static bool
2725 {
2726 /* We only need to wrap lvalue tree codes. */
2728 {
2762 /* Assume the worst for front-end tree codes. */
2766 }
2769 }
2771 /* Return an expr equal to X but certainly not valid as an lvalue. */
2773 tree
2775 {
2776 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2777 us. */
2784 }
2786 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2787 Zero means allow extended lvalues. */
2791 /* When pedantic, return an expr equal to X but certainly not valid as a
2792 pedantic lvalue. Otherwise, return X. */
2794 static tree
2796 {
2799 else
2801 }
2802 \f
2803 /* Given a tree comparison code, return the code that is the logical inverse
2804 of the given code. It is not safe to do this for floating-point
2805 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2806 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2808 enum tree_code
2810 {
2815 {
2846 }
2847 }
2849 /* Similar, but return the comparison that results if the operands are
2850 swapped. This is safe for floating-point. */
2852 enum tree_code
2854 {
2856 {
2882 }
2883 }
2886 /* Convert a comparison tree code from an enum tree_code representation
2887 into a compcode bit-based encoding. This function is the inverse of
2888 compcode_to_comparison. */
2890 static enum comparison_code
2892 {
2894 {
2925 }
2926 }
2928 /* Convert a compcode bit-based encoding of a comparison operator back
2929 to GCC's enum tree_code representation. This function is the
2930 inverse of comparison_to_compcode. */
2932 static enum tree_code
2934 {
2936 {
2967 }
2968 }
2970 /* Return a tree for the comparison which is the combination of
2971 doing the AND or OR (depending on CODE) of the two operations LCODE
2972 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2973 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2974 if this makes the transformation invalid. */
2976 tree
2980 {
2987 {
2998 }
3001 {
3002 /* Eliminate unordered comparisons, as well as LTGT and ORD
3003 which are not used unless the mode has NaNs. */
3009 }
3011 {
3012 /* Check that the original operation and the optimized ones will trap
3013 under the same condition. */
3024 /* In a short-circuited boolean expression the LHS might be
3025 such that the RHS, if evaluated, will never trap. For
3026 example, in ORD (x, y) && (x < y), we evaluate the RHS only
3027 if neither x nor y is NaN. (This is a mixed blessing: for
3028 example, the expression above will never trap, hence
3029 optimizing it to x < y would be invalid). */
3034 /* If the comparison was short-circuited, and only the RHS
3035 trapped, we may now generate a spurious trap. */
3040 /* If we changed the conditions that cause a trap, we lose. */
3043 }
3049 else
3050 {
3055 }
3056 }
3057 \f
3058 /* Return nonzero if two operands (typically of the same tree node)
3059 are necessarily equal. If either argument has side-effects this
3060 function returns zero. FLAGS modifies behavior as follows:
3062 If OEP_ONLY_CONST is set, only return nonzero for constants.
3063 This function tests whether the operands are indistinguishable;
3064 it does not test whether they are equal using C's == operation.
3065 The distinction is important for IEEE floating point, because
3066 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3067 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3069 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3070 even though it may hold multiple values during a function.
3071 This is because a GCC tree node guarantees that nothing else is
3072 executed between the evaluation of its "operands" (which may often
3073 be evaluated in arbitrary order). Hence if the operands themselves
3074 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3075 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3076 unset means assuming isochronic (or instantaneous) tree equivalence.
3077 Unless comparing arbitrary expression trees, such as from different
3078 statements, this flag can usually be left unset.
3080 If OEP_PURE_SAME is set, then pure functions with identical arguments
3081 are considered the same. It is used when the caller has other ways
3082 to ensure that global memory is unchanged in between. */
3084 int
3086 {
3087 /* If either is ERROR_MARK, they aren't equal. */
3091 /* Check equality of integer constants before bailing out due to
3092 precision differences. */
3096 /* If both types don't have the same signedness, then we can't consider
3097 them equal. We must check this before the STRIP_NOPS calls
3098 because they may change the signedness of the arguments. As pointers
3099 strictly don't have a signedness, require either two pointers or
3100 two non-pointers as well. */
3105 /* If both types don't have the same precision, then it is not safe
3106 to strip NOPs. */
3113 /* In case both args are comparisons but with different comparison
3114 code, try to swap the comparison operands of one arg to produce
3115 a match and compare that variant. */
3119 {
3127 }
3130 /* This is needed for conversions and for COMPONENT_REF.
3131 Might as well play it safe and always test this. */
3137 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3138 We don't care about side effects in that case because the SAVE_EXPR
3139 takes care of that for us. In all other cases, two expressions are
3140 equal if they have no side effects. If we have two identical
3141 expressions with side effects that should be treated the same due
3142 to the only side effects being identical SAVE_EXPR's, that will
3143 be detected in the recursive calls below. */
3149 /* Next handle constant cases, those for which we can return 1 even
3150 if ONLY_CONST is set. */
3153 {
3168 {
3169 /* If we do not distinguish between signed and unsigned zero,
3170 consider them equal. */
3173 }
3177 {
3183 {
3185 flags))
3189 }
3192 }
3196 flags)
3198 flags));
3211 }
3216 /* Define macros to test an operand from arg0 and arg1 for equality and a
3217 variant that allows null and views null as being different from any
3218 non-null value. In the latter case, if either is null, the both
3219 must be; otherwise, do the normal comparison. */
3220 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3221 TREE_OPERAND (arg1, N), flags)
3223 #define OP_SAME_WITH_NULL(N) \
3224 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3225 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3228 {
3230 /* Two conversions are equal only if signedness and modes match. */
3232 {
3233 CASE_CONVERT:
3241 }
3251 /* For commutative ops, allow the other order. */
3259 /* If either of the pointer (or reference) expressions we are
3260 dereferencing contain a side effect, these cannot be equal. */
3266 {
3276 /* Operands 2 and 3 may be null.
3277 Compare the array index by value if it is constant first as we
3278 may have different types but same value here. */
3287 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3288 may be NULL when we're called to compare MEM_EXPRs. */
3298 }
3302 {
3317 /* Otherwise take into account this is a commutative operation. */
3328 }
3332 {
3334 /* If the CALL_EXPRs call different functions, then they
3335 clearly can not be equal. */
3337 flags))
3340 {
3344 else
3348 }
3350 /* Now see if all the arguments are the same. */
3351 {
3362 /* If we get here and both argument lists are exhausted
3363 then the CALL_EXPRs are equal. */
3365 }
3368 }
3371 /* Consider __builtin_sqrt equal to sqrt. */
3379 }
3381 #undef OP_SAME
3382 #undef OP_SAME_WITH_NULL
3383 }
3384 \f
3385 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3386 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3388 When in doubt, return 0. */
3390 static int
3392 {
3404 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3405 and see if the inner values are the same. This removes any
3406 signedness comparison, which doesn't matter here. */
3413 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3414 actual comparison operand, ARG0.
3416 First throw away any conversions to wider types
3417 already present in the operands. */
3426 {
3429 /* Make sure shorter operand is extended the right way
3430 to match the longer operand. */
3436 }
3439 }
3440 \f
3441 /* See if ARG is an expression that is either a comparison or is performing
3442 arithmetic on comparisons. The comparisons must only be comparing
3443 two different values, which will be stored in *CVAL1 and *CVAL2; if
3444 they are nonzero it means that some operands have already been found.
3445 No variables may be used anywhere else in the expression except in the
3446 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3447 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3449 If this is true, return 1. Otherwise, return zero. */
3451 static int
3453 {
3457 /* We can handle some of the tcc_expression cases here. */
3467 {
3468 /* If we've already found a CVAL1 or CVAL2, this expression is
3469 two complex to handle. */
3475 }
3478 {
3501 /* First see if we can handle the first operand, then the second. For
3502 the second operand, we know *CVAL1 can't be zero. It must be that
3503 one side of the comparison is each of the values; test for the
3504 case where this isn't true by failing if the two operands
3505 are the same. */
3514 ;
3518 ;
3519 else
3523 ;
3527 ;
3528 else
3535 }
3536 }
3537 \f
3538 /* ARG is a tree that is known to contain just arithmetic operations and
3539 comparisons. Evaluate the operations in the tree substituting NEW0 for
3540 any occurrence of OLD0 as an operand of a comparison and likewise for
3541 NEW1 and OLD1. */
3543 static tree
3545 {
3550 /* We can handle some of the tcc_expression cases here. */
3558 {
3573 {
3590 }
3591 /* Fall through - ??? */
3594 {
3598 /* We need to check both for exact equality and tree equality. The
3599 former will be true if the operand has a side-effect. In that
3600 case, we know the operand occurred exactly once. */
3613 }
3617 }
3618 }
3619 \f
3620 /* Return a tree for the case when the result of an expression is RESULT
3621 converted to TYPE and OMITTED was previously an operand of the expression
3622 but is now not needed (e.g., we folded OMITTED * 0).
3624 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3625 the conversion of RESULT to TYPE. */
3627 tree
3629 {
3632 /* If the resulting operand is an empty statement, just return the omitted
3633 statement casted to void. */
3641 }
3643 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3645 static tree
3647 {
3650 /* If the resulting operand is an empty statement, just return the omitted
3651 statement casted to void. */
3659 }
3661 /* Return a tree for the case when the result of an expression is RESULT
3662 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3663 of the expression but are now not needed.
3665 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3666 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3667 evaluated before OMITTED2. Otherwise, if neither has side effects,
3668 just do the conversion of RESULT to TYPE. */
3670 tree
3672 {
3681 }
3683 \f
3684 /* Return a simplified tree node for the truth-negation of ARG. This
3685 never alters ARG itself. We assume that ARG is an operation that
3686 returns a truth value (0 or 1).
3688 FIXME: one would think we would fold the result, but it causes
3689 problems with the dominator optimizer. */
3691 tree
3693 {
3697 /* If this is a comparison, we can simply invert it, except for
3698 floating-point non-equality comparisons, in which case we just
3699 enclose a TRUTH_NOT_EXPR around what we have. */
3702 {
3705 && flag_trapping_math
3718 }
3721 {
3738 /* Here we can invert either operand. We invert the first operand
3739 unless the second operand is a TRUTH_NOT_EXPR in which case our
3740 result is the XOR of the first operand with the inside of the
3741 negation of the second operand. */
3746 else
3768 {
3771 /* A COND_EXPR may have a throw as one operand, which
3772 then has void type. Just leave void operands
3773 as they are. */
3780 }
3790 CASE_CONVERT:
3792 {
3795 }
3797 /* ... fall through ... */
3822 }
3828 }
3830 /* Return a simplified tree node for the truth-negation of ARG. This
3831 never alters ARG itself. We assume that ARG is an operation that
3832 returns a truth value (0 or 1).
3834 FIXME: one would think we would fold the result, but it causes
3835 problems with the dominator optimizer. */
3837 tree
3839 {
3840 tree tem;
3850 }
3852 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3853 operands are another bit-wise operation with a common input. If so,
3854 distribute the bit operations to save an operation and possibly two if
3855 constants are involved. For example, convert
3856 (A | B) & (A | C) into A | (B & C)
3857 Further simplification will occur if B and C are constants.
3859 If this optimization cannot be done, 0 will be returned. */
3861 static tree
3863 {
3864 tree common;
3874 {
3878 }
3880 {
3884 }
3886 {
3890 }
3892 {
3896 }
3897 else
3905 }
3907 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3908 with code CODE. This optimization is unsafe. */
3909 static tree
3911 {
3915 /* (A / C) +- (B / C) -> (A +- B) / C. */
3925 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3930 {
3942 }
3945 }
3946 \f
3947 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3948 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3950 static tree
3953 {
3957 {
3964 }
3978 }
3980 /* Optimize a bit-field compare.
3982 There are two cases: First is a compare against a constant and the
3983 second is a comparison of two items where the fields are at the same
3984 bit position relative to the start of a chunk (byte, halfword, word)
3985 large enough to contain it. In these cases we can avoid the shift
3986 implicit in bitfield extractions.
3988 For constants, we emit a compare of the shifted constant with the
3989 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3990 compared. For two fields at the same position, we do the ANDs with the
3991 similar mask and compare the result of the ANDs.
3993 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3994 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3995 are the left and right operands of the comparison, respectively.
3997 If the optimization described above can be done, we return the resulting
3998 tree. Otherwise we return zero. */
4000 static tree
4003 {
4012 tree mask;
4013 tree offset;
4015 /* Get all the information about the extractions being done. If the bit size
4016 if the same as the size of the underlying object, we aren't doing an
4017 extraction at all and so can do nothing. We also don't want to
4018 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4019 then will no longer be able to replace it. */
4027 {
4028 /* If this is not a constant, we can only do something if bit positions,
4029 sizes, and signedness are the same. */
4037 }
4039 /* See if we can find a mode to refer to this field. We should be able to,
4040 but fail if we can't. */
4049 /* Set signed and unsigned types of the precision of this mode for the
4050 shifts below. */
4054 /* Compute the bit position and size for the new reference and our offset
4055 within it. If the new reference is the same size as the original, we
4056 won't optimize anything, so return zero. */
4066 /* Make the mask to be used against the extracted field. */
4073 /* If not comparing with constant, just rework the comparison
4074 and return. */
4078 unsigned_type,
4081 mask),
4084 unsigned_type,
4087 mask));
4089 /* Otherwise, we are handling the constant case. See if the constant is too
4090 big for the field. Warn and return a tree of for 0 (false) if so. We do
4091 this not only for its own sake, but to avoid having to test for this
4092 error case below. If we didn't, we might generate wrong code.
4094 For unsigned fields, the constant shifted right by the field length should
4095 be all zero. For signed fields, the high-order bits should agree with
4096 the sign bit. */
4099 {
4103 {
4107 }
4108 }
4109 else
4110 {
4114 {
4118 }
4119 }
4121 /* Single-bit compares should always be against zero. */
4123 {
4126 }
4128 /* Make a new bitfield reference, shift the constant over the
4129 appropriate number of bits and mask it with the computed mask
4130 (in case this was a signed field). If we changed it, make a new one. */
4133 {
4136 }
4146 rhs);
4147 }
4148 \f
4149 /* Subroutine for fold_truthop: decode a field reference.
4151 If EXP is a comparison reference, we return the innermost reference.
4153 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4154 set to the starting bit number.
4156 If the innermost field can be completely contained in a mode-sized
4157 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4159 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4160 otherwise it is not changed.
4162 *PUNSIGNEDP is set to the signedness of the field.
4164 *PMASK is set to the mask used. This is either contained in a
4165 BIT_AND_EXPR or derived from the width of the field.
4167 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4169 Return 0 if this is not a component reference or is one that we can't
4170 do anything with. */
4172 static tree
4177 {
4181 tree unsigned_type;
4184 /* All the optimizations using this function assume integer fields.
4185 There are problems with FP fields since the type_for_size call
4186 below can fail for, e.g., XFmode. */
4190 /* We are interested in the bare arrangement of bits, so strip everything
4191 that doesn't affect the machine mode. However, record the type of the
4192 outermost expression if it may matter below. */
4199 {
4205 }
4214 /* If the number of bits in the reference is the same as the bitsize of
4215 the outer type, then the outer type gives the signedness. Otherwise
4216 (in case of a small bitfield) the signedness is unchanged. */
4220 /* Compute the mask to access the bitfield. */
4229 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4237 }
4239 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4240 bit positions. */
4242 static int
4244 {
4247 tree tmask;
4251 return
4258 }
4260 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4261 represents the sign bit of EXP's type. If EXP represents a sign
4262 or zero extension, also test VAL against the unextended type.
4263 The return value is the (sub)expression whose sign bit is VAL,
4264 or NULL_TREE otherwise. */
4266 static tree
4268 {
4272 tree t;
4274 /* Tree EXP must have an integral type. */
4279 /* Tree VAL must be an integer constant. */
4286 {
4293 }
4294 else
4295 {
4302 }
4304 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4305 treat VAL as if it were unsigned. */
4310 /* Handle extension from a narrower type. */
4316 }
4318 /* Subroutine for fold_truthop: determine if an operand is simple enough
4319 to be evaluated unconditionally. */
4321 static int
4323 {
4324 /* Strip any conversions that don't change the machine mode. */
4333 /* Don't regard global variables as simple. They may be
4334 allocated in ways unknown to the compiler (shared memory,
4335 #pragma weak, etc). */
4338 /* Loading a static variable is unduly expensive, but global
4339 registers aren't expensive. */
4341 }
4342 \f
4343 /* The following functions are subroutines to fold_range_test and allow it to
4344 try to change a logical combination of comparisons into a range test.
4346 For example, both
4347 X == 2 || X == 3 || X == 4 || X == 5
4348 and
4349 X >= 2 && X <= 5
4350 are converted to
4351 (unsigned) (X - 2) <= 3
4353 We describe each set of comparisons as being either inside or outside
4354 a range, using a variable named like IN_P, and then describe the
4355 range with a lower and upper bound. If one of the bounds is omitted,
4356 it represents either the highest or lowest value of the type.
4358 In the comments below, we represent a range by two numbers in brackets
4359 preceded by a "+" to designate being inside that range, or a "-" to
4360 designate being outside that range, so the condition can be inverted by
4361 flipping the prefix. An omitted bound is represented by a "-". For
4362 example, "- [-, 10]" means being outside the range starting at the lowest
4363 possible value and ending at 10, in other words, being greater than 10.
4364 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4365 always false.
4367 We set up things so that the missing bounds are handled in a consistent
4368 manner so neither a missing bound nor "true" and "false" need to be
4369 handled using a special case. */
4371 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4372 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4373 and UPPER1_P are nonzero if the respective argument is an upper bound
4374 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4375 must be specified for a comparison. ARG1 will be converted to ARG0's
4376 type if both are specified. */
4378 static tree
4381 {
4382 tree tem;
4386 /* If neither arg represents infinity, do the normal operation.
4387 Else, if not a comparison, return infinity. Else handle the special
4388 comparison rules. Note that most of the cases below won't occur, but
4389 are handled for consistency. */
4392 {
4397 }
4402 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4403 for neither. In real maths, we cannot assume open ended ranges are
4404 the same. But, this is computer arithmetic, where numbers are finite.
4405 We can therefore make the transformation of any unbounded range with
4406 the value Z, Z being greater than any representable number. This permits
4407 us to treat unbounded ranges as equal. */
4411 {
4432 }
4435 }
4436 \f
4437 /* Given EXP, a logical expression, set the range it is testing into
4438 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4439 actually being tested. *PLOW and *PHIGH will be made of the same
4440 type as the returned expression. If EXP is not a comparison, we
4441 will most likely not be returning a useful value and range. Set
4442 *STRICT_OVERFLOW_P to true if the return value is only valid
4443 because signed overflow is undefined; otherwise, do not change
4444 *STRICT_OVERFLOW_P. */
4446 tree
4449 {
4456 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4457 and see if we can refine the range. Some of the cases below may not
4458 happen, but it doesn't seem worth worrying about this. We "continue"
4459 the outer loop when we've changed something; otherwise we "break"
4460 the switch, which will "break" the while. */
4466 {
4471 {
4483 }
4486 {
4493 /* We can only do something if the range is testing for zero
4494 and if the second operand is an integer constant. Note that
4495 saying something is "in" the range we make is done by
4496 complementing IN_P since it will set in the initial case of
4497 being not equal to zero; "out" is leaving it alone. */
4504 {
4525 }
4527 /* If this is an unsigned comparison, we also know that EXP is
4528 greater than or equal to zero. We base the range tests we make
4529 on that fact, so we record it here so we can parse existing
4530 range tests. We test arg0_type since often the return type
4531 of, e.g. EQ_EXPR, is boolean. */
4533 {
4537 NULL_TREE))
4542 /* If the high bound is missing, but we have a nonzero low
4543 bound, reverse the range so it goes from zero to the low bound
4544 minus 1. */
4546 {
4551 }
4552 }
4558 /* (-x) IN [a,b] -> x in [-b, -a] */
4570 /* ~ X -> -X - 1 */
4579 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4580 move a constant to the other side. */
4585 /* If EXP is signed, any overflow in the computation is undefined,
4586 so we don't worry about it so long as our computations on
4587 the bounds don't overflow. For unsigned, overflow is defined
4588 and this is exactly the right thing. */
4600 /* Check for an unsigned range which has wrapped around the maximum
4601 value thus making n_high < n_low, and normalize it. */
4603 {
4609 /* If the range is of the form +/- [ x+1, x ], we won't
4610 be able to normalize it. But then, it represents the
4611 whole range or the empty set, so make it
4612 +/- [ -, - ]. */
4616 else
4618 }
4619 else
4643 /* If we're converting arg0 from an unsigned type, to exp,
4644 a signed type, we will be doing the comparison as unsigned.
4645 The tests above have already verified that LOW and HIGH
4646 are both positive.
4648 So we have to ensure that we will handle large unsigned
4649 values the same way that the current signed bounds treat
4650 negative values. */
4653 {
4654 tree high_positive;
4655 tree equiv_type;
4656 /* For fixed-point modes, we need to pass the saturating flag
4657 as the 2nd parameter. */
4662 else
4666 /* A range without an upper bound is, naturally, unbounded.
4667 Since convert would have cropped a very large value, use
4668 the max value for the destination type. */
4669 high_positive
4676 high_positive),
4679 /* If the low bound is specified, "and" the range with the
4680 range for which the original unsigned value will be
4681 positive. */
4683 {
4687 integer_zero_node),
4688 high_positive))
4692 }
4693 else
4694 {
4695 /* Otherwise, "or" the range with the range of the input
4696 that will be interpreted as negative. */
4700 integer_zero_node),
4701 high_positive))
4705 }
4706 }
4714 }
4717 }
4719 /* If EXP is a constant, we can evaluate whether this is true or false. */
4721 {
4728 }
4732 }
4733 \f
4734 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4735 type, TYPE, return an expression to test if EXP is in (or out of, depending
4736 on IN_P) the range. Return 0 if the test couldn't be created. */
4738 tree
4740 {
4743 #ifdef HAVE_canonicalize_funcptr_for_compare
4744 /* Disable this optimization for function pointer expressions
4745 on targets that require function pointer canonicalization. */
4750 #endif
4753 {
4759 }
4777 {
4779 {
4783 }
4785 }
4787 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4789 {
4791 HOST_WIDE_INT hi;
4796 {
4799 }
4800 else
4801 {
4804 }
4807 {
4809 {
4812 etype
4814 else
4817 }
4820 }
4821 }
4823 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4824 This requires wrap-around arithmetics for the type of the expression.
4825 First make sure that arithmetics in this type is valid, then make sure
4826 that it wraps around. */
4833 {
4836 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4837 for the type in question, as we rely on this here. */
4847 else
4849 }
4859 {
4861 {
4867 }
4869 }
4877 }
4878 \f
4879 /* Return the predecessor of VAL in its type, handling the infinite case. */
4881 static tree
4883 {
4889 else
4891 }
4893 /* Return the successor of VAL in its type, handling the infinite case. */
4895 static tree
4897 {
4903 else
4905 }
4907 /* Given two ranges, see if we can merge them into one. Return 1 if we
4908 can, 0 if we can't. Set the output range into the specified parameters. */
4910 bool
4913 {
4917 tree tem;
4927 /* Make range 0 be the range that starts first, or ends last if they
4928 start at the same value. Swap them if it isn't. */
4931 || (lowequal
4934 {
4938 }
4940 /* Now flag two cases, whether the ranges are disjoint or whether the
4941 second range is totally subsumed in the first. Note that the tests
4942 below are simplified by the ones above. */
4948 /* We now have four cases, depending on whether we are including or
4949 excluding the two ranges. */
4951 {
4952 /* If they don't overlap, the result is false. If the second range
4953 is a subset it is the result. Otherwise, the range is from the start
4954 of the second to the end of the first. */
4959 else
4961 }
4964 {
4965 /* If they don't overlap, the result is the first range. If they are
4966 equal, the result is false. If the second range is a subset of the
4967 first, and the ranges begin at the same place, we go from just after
4968 the end of the second range to the end of the first. If the second
4969 range is not a subset of the first, or if it is a subset and both
4970 ranges end at the same place, the range starts at the start of the
4971 first range and ends just before the second range.
4972 Otherwise, we can't describe this as a single range. */
4978 {
4983 {
4984 /* We are in the weird situation where high0 > high1 but
4985 high1 has no successor. Punt. */
4987 }
4988 }
4990 {
4995 {
4996 /* low0 < low1 but low1 has no predecessor. Punt. */
4998 }
4999 }
5000 else
5002 }
5005 {
5006 /* If they don't overlap, the result is the second range. If the second
5007 is a subset of the first, the result is false. Otherwise,
5008 the range starts just after the first range and ends at the
5009 end of the second. */
5014 else
5015 {
5020 {
5021 /* high1 > high0 but high0 has no successor. Punt. */
5023 }
5024 }
5025 }
5027 else
5028 {
5029 /* The case where we are excluding both ranges. Here the complex case
5030 is if they don't overlap. In that case, the only time we have a
5031 range is if they are adjacent. If the second is a subset of the
5032 first, the result is the first. Otherwise, the range to exclude
5033 starts at the beginning of the first range and ends at the end of the
5034 second. */
5036 {
5041 else
5042 {
5043 /* Canonicalize - [min, x] into - [-, x]. */
5046 {
5051 /* FALLTHROUGH */
5064 }
5066 /* Canonicalize - [x, max] into - [x, -]. */
5069 {
5074 /* FALLTHROUGH */
5089 }
5091 /* The ranges might be also adjacent between the maximum and
5092 minimum values of the given type. For
5093 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5094 return + [x + 1, y - 1]. */
5096 {
5103 }
5104 else
5106 }
5107 }
5110 else
5112 }
5116 }
5117 \f
5119 /* Subroutine of fold, looking inside expressions of the form
5120 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5121 of the COND_EXPR. This function is being used also to optimize
5122 A op B ? C : A, by reversing the comparison first.
5124 Return a folded expression whose code is not a COND_EXPR
5125 anymore, or NULL_TREE if no folding opportunity is found. */
5127 static tree
5129 {
5134 tree tem;
5139 /* If we have A op 0 ? A : -A, consider applying the following
5140 transformations:
5142 A == 0? A : -A same as -A
5143 A != 0? A : -A same as A
5144 A >= 0? A : -A same as abs (A)
5145 A > 0? A : -A same as abs (A)
5146 A <= 0? A : -A same as -abs (A)
5147 A < 0? A : -A same as -abs (A)
5149 None of these transformations work for modes with signed
5150 zeros. If A is +/-0, the first two transformations will
5151 change the sign of the result (from +0 to -0, or vice
5152 versa). The last four will fix the sign of the result,
5153 even though the original expressions could be positive or
5154 negative, depending on the sign of A.
5156 Note that all these transformations are correct if A is
5157 NaN, since the two alternatives (A and -A) are also NaNs. */
5164 /* In the case that A is of the form X-Y, '-A' (arg2) may
5165 have already been folded to Y-X, check for that. */
5173 {
5185 /* Fall through. */
5207 }
5209 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5210 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5211 both transformations are correct when A is NaN: A != 0
5212 is then true, and A == 0 is false. */
5216 {
5221 }
5223 /* Try some transformations of A op B ? A : B.
5225 A == B? A : B same as B
5226 A != B? A : B same as A
5227 A >= B? A : B same as max (A, B)
5228 A > B? A : B same as max (B, A)
5229 A <= B? A : B same as min (A, B)
5230 A < B? A : B same as min (B, A)
5232 As above, these transformations don't work in the presence
5233 of signed zeros. For example, if A and B are zeros of
5234 opposite sign, the first two transformations will change
5235 the sign of the result. In the last four, the original
5236 expressions give different results for (A=+0, B=-0) and
5237 (A=-0, B=+0), but the transformed expressions do not.
5239 The first two transformations are correct if either A or B
5240 is a NaN. In the first transformation, the condition will
5241 be false, and B will indeed be chosen. In the case of the
5242 second transformation, the condition A != B will be true,
5243 and A will be chosen.
5245 The conversions to max() and min() are not correct if B is
5246 a number and A is not. The conditions in the original
5247 expressions will be false, so all four give B. The min()
5248 and max() versions would give a NaN instead. */
5251 /* Avoid these transformations if the COND_EXPR may be used
5252 as an lvalue in the C++ front-end. PR c++/19199. */
5253 && (in_gimple_form
5258 {
5263 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5265 {
5269 }
5272 {
5281 /* In C++ a ?: expression can be an lvalue, so put the
5282 operand which will be used if they are equal first
5283 so that we can convert this back to the
5284 corresponding COND_EXPR. */
5286 {
5293 }
5300 {
5307 }
5320 }
5321 }
5323 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5324 we might still be able to simplify this. For example,
5325 if C1 is one less or one more than C2, this might have started
5326 out as a MIN or MAX and been transformed by this function.
5327 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5333 {
5337 /* We can replace A with C1 in this case. */
5342 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5343 MIN_EXPR, to preserve the signedness of the comparison. */
5345 OEP_ONLY_CONST)
5349 OEP_ONLY_CONST))
5350 {
5354 }
5358 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5359 as above. */
5361 OEP_ONLY_CONST)
5365 OEP_ONLY_CONST))
5366 {
5370 }
5374 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5375 MAX_EXPR, to preserve the signedness of the comparison. */
5377 OEP_ONLY_CONST)
5381 OEP_ONLY_CONST))
5382 {
5386 }
5390 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5392 OEP_ONLY_CONST)
5396 OEP_ONLY_CONST))
5397 {
5401 }
5407 }
5410 }
5413 \f
5414 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5415 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5416 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5417 false) >= 2)
5418 #endif
5420 /* EXP is some logical combination of boolean tests. See if we can
5421 merge it into some range test. Return the new tree if so. */
5423 static tree
5425 {
5433 tree tem;
5437 /* If this is an OR operation, invert both sides; we will invert
5438 again at the end. */
5442 /* If both expressions are the same, if we can merge the ranges, and we
5443 can build the range test, return it or it inverted. If one of the
5444 ranges is always true or always false, consider it to be the same
5445 expression as the other. */
5453 {
5457 }
5459 /* On machines where the branch cost is expensive, if this is a
5460 short-circuited branch and the underlying object on both sides
5461 is the same, make a non-short-circuit operation. */
5467 {
5468 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5469 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5470 which cases we can't do this. */
5478 {
5487 {
5490 WARN_STRICT_OVERFLOW_COMPARISON);
5494 }
5495 }
5496 }
5499 }
5500 \f
5501 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5502 bit value. Arrange things so the extra bits will be set to zero if and
5503 only if C is signed-extended to its full width. If MASK is nonzero,
5504 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5506 static tree
5508 {
5511 tree temp;
5516 /* We work by getting just the sign bit into the low-order bit, then
5517 into the high-order bit, then sign-extend. We then XOR that value
5518 with C. */
5522 /* We must use a signed type in order to get an arithmetic right shift.
5523 However, we must also avoid introducing accidental overflows, so that
5524 a subsequent call to integer_zerop will work. Hence we must
5525 do the type conversion here. At this point, the constant is either
5526 zero or one, and the conversion to a signed type can never overflow.
5527 We could get an overflow if this conversion is done anywhere else. */
5536 /* If necessary, convert the type back to match the type of C. */
5541 }
5542 \f
5543 /* Find ways of folding logical expressions of LHS and RHS:
5544 Try to merge two comparisons to the same innermost item.
5545 Look for range tests like "ch >= '0' && ch <= '9'".
5546 Look for combinations of simple terms on machines with expensive branches
5547 and evaluate the RHS unconditionally.
5549 For example, if we have p->a == 2 && p->b == 4 and we can make an
5550 object large enough to span both A and B, we can do this with a comparison
5551 against the object ANDed with the a mask.
5553 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5554 operations to do this with one comparison.
5556 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5557 function and the one above.
5559 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5560 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5562 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5563 two operands.
5565 We return the simplified tree or 0 if no optimization is possible. */
5567 static tree
5569 {
5570 /* If this is the "or" of two comparisons, we can do something if
5571 the comparisons are NE_EXPR. If this is the "and", we can do something
5572 if the comparisons are EQ_EXPR. I.e.,
5573 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5575 WANTED_CODE is this operation code. For single bit fields, we can
5576 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5577 comparison for one-bit fields. */
5599 /* Start by getting the comparison codes. Fail if anything is volatile.
5600 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5601 it were surrounded with a NE_EXPR. */
5610 {
5614 }
5617 {
5621 }
5632 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5635 {
5636 tree result;
5639 {
5644 }
5647 {
5653 }
5654 }
5659 /* If the RHS can be evaluated unconditionally and its operands are
5660 simple, it wins to evaluate the RHS unconditionally on machines
5661 with expensive branches. In this case, this isn't a comparison
5662 that can be merged. Avoid doing this if the RHS is a floating-point
5663 comparison since those can trap. */
5670 {
5671 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5682 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5694 {
5698 }
5699 }
5701 /* See if the comparisons can be merged. Then get all the parameters for
5702 each side. */
5726 /* It must be true that the inner operation on the lhs of each
5727 comparison must be the same if we are to be able to do anything.
5728 Then see if we have constants. If not, the same must be true for
5729 the rhs's. */
5740 else
5743 /* If either comparison code is not correct for our logical operation,
5744 fail. However, we can convert a one-bit comparison against zero into
5745 the opposite comparison against that bit being set in the field. */
5749 {
5751 {
5752 /* Make the left operand unsigned, since we are only interested
5753 in the value of one bit. Otherwise we are doing the wrong
5754 thing below. */
5757 }
5758 else
5760 }
5762 /* This is analogous to the code for l_const above. */
5764 {
5766 {
5769 }
5770 else
5772 }
5774 /* See if we can find a mode that contains both fields being compared on
5775 the left. If we can't, fail. Otherwise, update all constants and masks
5776 to be relative to a field of that size. */
5781 volatilep);
5791 {
5794 }
5802 {
5810 {
5814 }
5815 }
5817 {
5825 {
5829 }
5830 }
5832 /* If the right sides are not constant, do the same for it. Also,
5833 disallow this optimization if a size or signedness mismatch occurs
5834 between the left and right sides. */
5836 {
5839 /* Make sure the two fields on the right
5840 correspond to the left without being swapped. */
5848 volatilep);
5858 {
5861 }
5868 /* Make a mask that corresponds to both fields being compared.
5869 Do this for both items being compared. If the operands are the
5870 same size and the bits being compared are in the same position
5871 then we can do this by masking both and comparing the masked
5872 results. */
5876 {
5888 }
5890 /* There is still another way we can do something: If both pairs of
5891 fields being compared are adjacent, we may be able to make a wider
5892 field containing them both.
5894 Note that we still must mask the lhs/rhs expressions. Furthermore,
5895 the mask must be shifted to account for the shift done by
5896 make_bit_field_ref. */
5901 {
5902 tree type;
5914 /* Convert to the smaller type before masking out unwanted bits. */
5917 {
5919 {
5923 }
5925 {
5929 }
5930 }
5939 }
5942 }
5944 /* Handle the case of comparisons with constants. If there is something in
5945 common between the masks, those bits of the constants must be the same.
5946 If not, the condition is always false. Test for this to avoid generating
5947 incorrect code below. */
5952 {
5954 {
5957 }
5958 else
5959 {
5962 }
5963 }
5965 /* Construct the expression we will return. First get the component
5966 reference we will make. Unless the mask is all ones the width of
5967 that field, perform the mask operation. Then compare with the
5968 merged constant. */
5978 }
5979 \f
5980 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5981 constant. */
5983 static tree
5985 {
5988 tree comp_const;
5989 tree minmax_const;
5991 tree inner;
6002 /* If something does not permit us to optimize, return the original tree. */
6010 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6011 and GT_EXPR, doing the rest with recursive calls using logical
6012 simplifications. */
6014 {
6016 {
6022 }
6025 return
6027 optimize_minmax_comparison
6029 optimize_minmax_comparison
6034 /* MAX (X, 0) == 0 -> X <= 0 */
6038 /* MAX (X, 0) == 5 -> X == 5 */
6042 /* MAX (X, 0) == -1 -> false */
6046 /* MIN (X, 0) == 0 -> X >= 0 */
6050 /* MIN (X, 0) == 5 -> false */
6053 else
6054 /* MIN (X, 0) == -1 -> X == -1 */
6059 /* MAX (X, 0) > 0 -> X > 0
6060 MAX (X, 0) > 5 -> X > 5 */
6064 /* MAX (X, 0) > -1 -> true */
6068 /* MIN (X, 0) > 0 -> false
6069 MIN (X, 0) > 5 -> false */
6072 else
6073 /* MIN (X, 0) > -1 -> X > -1 */
6078 }
6079 }
6080 \f
6081 /* T is an integer expression that is being multiplied, divided, or taken a
6082 modulus (CODE says which and what kind of divide or modulus) by a
6083 constant C. See if we can eliminate that operation by folding it with
6084 other operations already in T. WIDE_TYPE, if non-null, is a type that
6085 should be used for the computation if wider than our type.
6087 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6088 (X * 2) + (Y * 4). We must, however, be assured that either the original
6089 expression would not overflow or that overflow is undefined for the type
6090 in the language in question.
6092 If we return a non-null expression, it is an equivalent form of the
6093 original computation, but need not be in the original type.
6095 We set *STRICT_OVERFLOW_P to true if the return values depends on
6096 signed overflow being undefined. Otherwise we do not change
6097 *STRICT_OVERFLOW_P. */
6099 static tree
6102 {
6103 /* To avoid exponential search depth, refuse to allow recursion past
6104 three levels. Beyond that (1) it's highly unlikely that we'll find
6105 something interesting and (2) we've probably processed it before
6106 when we built the inner expression. */
6109 tree ret;
6114 depth++;
6116 depth--;
6119 }
6121 static tree
6124 {
6135 /* Don't deal with constants of zero here; they confuse the code below. */
6145 /* Note that we need not handle conditional operations here since fold
6146 already handles those cases. So just do arithmetic here. */
6148 {
6150 /* For a constant, we can always simplify if we are a multiply
6151 or (for divide and modulus) if it is a multiple of our constant. */
6159 /* If op0 is an expression ... */
6165 /* ... and possibly overflows, and its type is smaller
6166 than ctype, then we cannot pass through as widening. */
6168 /* ??? Remove me. */
6173 /* ... or this is a truncation (t is narrower than op0),
6174 then we cannot pass through this narrowing. */
6177 /* ... or signedness changes for division or modulus,
6178 then we cannot pass through this conversion. */
6184 /* Pass the constant down and see if we can make a simplification. If
6185 we can, replace this expression with the inner simplification for
6186 possible later conversion to our or some other type. */
6193 strict_overflow_p))))
6198 /* If widening the type changes it from signed to unsigned, then we
6199 must avoid building ABS_EXPR itself as unsigned. */
6201 {
6205 {
6208 }
6210 }
6211 /* If the constant is negative, we cannot simplify this. */
6214 /* FALLTHROUGH */
6223 /* If widening the type changes the signedness, then we can't perform
6224 this optimization as that changes the result. */
6228 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6234 {
6241 }
6245 /* If the second operand is constant, this is a multiplication
6246 or floor division, by a power of two, so we can treat it that
6247 way unless the multiplier or divisor overflows. Signed
6248 left-shift overflow is implementation-defined rather than
6249 undefined in C90, so do not convert signed left shift into
6250 multiplication. */
6253 /* const_binop may not detect overflow correctly,
6254 so check for it explicitly here. */
6259 size_one_node,
6272 /* See if we can eliminate the operation on both sides. If we can, we
6273 can return a new PLUS or MINUS. If we can't, the only remaining
6274 cases where we can do anything are if the second operand is a
6275 constant. */
6281 /* If not multiplication, we can only do this if both operands
6282 are divisible by c. */
6285 {
6290 }
6292 /* If this was a subtraction, negate OP1 and set it to be an addition.
6293 This simplifies the logic below. */
6300 /* If either OP1 or C are negative, this optimization is not safe for
6301 some of the division and remainder types while for others we need
6302 to change the code. */
6304 {
6312 }
6314 /* If it's a multiply or a division/modulus operation of a multiple
6315 of our constant, do the operation. */
6318 {
6323 }
6324 else
6327 /* If the original operation possibly overflowed we cannot widen
6328 the operation since it will change the result. */
6333 /* If we were able to eliminate our operation from the first side,
6334 apply our operation to the second side and reform the PLUS. */
6340 /* The last case is if we are a multiply. In that case, we can
6341 apply the distributive law to commute the multiply and addition
6342 if the multiplication of the constants doesn't overflow. */
6348 op1);
6354 /* We have a special case here if we are doing something like
6355 (C * 8) % 4 since we know that's zero. */
6358 /* If the multiplication can overflow we cannot optimize this. */
6360 /* ??? Until we can properly mark individual operations as
6361 not overflowing we need to treat sizetype special here as
6362 stor-layout relies on this opimization to make
6363 DECL_FIELD_BIT_OFFSET always a constant. */
6368 {
6371 }
6373 /* ... fall through ... */
6377 /* If we can extract our operation from the LHS, do so and return a
6378 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6379 do something only if the second operand is a constant. */
6395 /* If these are the same operation types, we can associate them
6396 assuming no overflow.
6397 ??? Why only for no overflow? */
6410 /* If these operations "cancel" each other, we have the main
6411 optimizations of this pass, which occur when either constant is a
6412 multiple of the other, in which case we replace this with either an
6413 operation or CODE or TCODE.
6415 If we have an unsigned type that is not a sizetype, we cannot do
6416 this since it will change the result if the original computation
6417 overflowed. */
6423 {
6425 {
6432 }
6434 {
6441 }
6442 }
6447 }
6450 }
6451 \f
6452 /* Return a node which has the indicated constant VALUE (either 0 or
6453 1), and is of the indicated TYPE. */
6455 tree
6457 {
6462 else
6464 }
6467 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6468 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6469 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6470 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6471 COND is the first argument to CODE; otherwise (as in the example
6472 given here), it is the second argument. TYPE is the type of the
6473 original expression. Return NULL_TREE if no simplification is
6474 possible. */
6476 static tree
6480 {
6487 /* This transformation is only worthwhile if we don't have to wrap
6488 arg in a SAVE_EXPR, and the operation can be simplified on at least
6489 one of the branches once its pushed inside the COND_EXPR. */
6494 {
6498 /* If this operand throws an expression, then it does not make
6499 sense to try to perform a logical or arithmetic operation
6500 involving it. */
6505 }
6506 else
6507 {
6512 }
6516 {
6520 else
6522 }
6524 {
6528 else
6530 }
6534 }
6536 \f
6537 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6539 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6540 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6541 ADDEND is the same as X.
6543 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6544 and finite. The problematic cases are when X is zero, and its mode
6545 has signed zeros. In the case of rounding towards -infinity,
6546 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6547 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6549 bool
6551 {
6555 /* Don't allow the fold with -fsignaling-nans. */
6559 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6563 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6568 /* The mode has signed zeros, and we have to honor their sign.
6569 In this situation, there is only one case we can return true for.
6570 X - 0 is the same as X unless rounding towards -infinity is
6571 supported. */
6573 }
6575 /* Subroutine of fold() that checks comparisons of built-in math
6576 functions against real constants.
6578 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6579 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6580 is the type of the result and ARG0 and ARG1 are the operands of the
6581 comparison. ARG1 must be a TREE_REAL_CST.
6583 The function returns the constant folded tree if a simplification
6584 can be made, and NULL_TREE otherwise. */
6586 static tree
6589 {
6590 REAL_VALUE_TYPE c;
6593 {
6599 {
6600 /* sqrt(x) < y is always false, if y is negative. */
6604 /* sqrt(x) > y is always true, if y is negative and we
6605 don't care about NaNs, i.e. negative values of x. */
6609 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6612 }
6614 {
6615 REAL_VALUE_TYPE c2;
6621 {
6622 /* sqrt(x) > y is x == +Inf, when y is very large. */
6627 /* sqrt(x) > y is always false, when y is very large
6628 and we don't care about infinities. */
6630 }
6632 /* sqrt(x) > c is the same as x > c*c. */
6635 }
6637 {
6638 REAL_VALUE_TYPE c2;
6644 {
6645 /* sqrt(x) < y is always true, when y is a very large
6646 value and we don't care about NaNs or Infinities. */
6650 /* sqrt(x) < y is x != +Inf when y is very large and we
6651 don't care about NaNs. */
6656 /* sqrt(x) < y is x >= 0 when y is very large and we
6657 don't care about Infinities. */
6662 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6671 dconst0)),
6674 c2)));
6675 }
6677 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6682 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6685 {
6690 dconst0)),
6693 c2)));
6694 }
6695 }
6696 }
6699 }
6701 /* Subroutine of fold() that optimizes comparisons against Infinities,
6702 either +Inf or -Inf.
6704 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6705 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6706 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6708 The function returns the constant folded tree if a simplification
6709 can be made, and NULL_TREE otherwise. */
6711 static tree
6713 {
6715 REAL_VALUE_TYPE max;
6716 tree temp;
6721 /* For negative infinity swap the sense of the comparison. */
6727 {
6729 /* x > +Inf is always false, if with ignore sNANs. */
6735 /* x <= +Inf is always true, if we don't case about NaNs. */
6739 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6742 {
6745 }
6750 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6756 /* x < +Inf is always equal to x <= DBL_MAX. */
6762 /* x != +Inf is always equal to !(x > DBL_MAX). */
6774 }
6777 }
6779 /* Subroutine of fold() that optimizes comparisons of a division by
6780 a nonzero integer constant against an integer constant, i.e.
6781 X/C1 op C2.
6783 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6784 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6785 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6787 The function returns the constant folded tree if a simplification
6788 can be made, and NULL_TREE otherwise. */
6790 static tree
6792 {
6797 HOST_WIDE_INT hpart;
6802 /* We have to do this the hard way to detect unsigned overflow.
6803 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6814 {
6819 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6827 }
6829 {
6833 {
6852 }
6853 }
6854 else
6855 {
6856 /* A negative divisor reverses the relational operators. */
6862 {
6881 }
6882 }
6885 {
6906 {
6909 }
6914 {
6917 }
6922 {
6925 }
6930 {
6933 }
6938 }
6941 }
6944 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6945 equality/inequality test, then return a simplified form of the test
6946 using a sign testing. Otherwise return NULL. TYPE is the desired
6947 result type. */
6949 static tree
6951 tree result_type)
6952 {
6953 /* If this is testing a single bit, we can optimize the test. */
6957 {
6958 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6959 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6963 /* This is only a win if casting to a signed type is cheap,
6964 i.e. when arg00's type is not a partial mode. */
6967 {
6972 }
6973 }
6976 }
6978 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6979 equality/inequality test, then return a simplified form of
6980 the test using shifts and logical operations. Otherwise return
6981 NULL. TYPE is the desired result type. */
6983 tree
6985 tree result_type)
6986 {
6987 /* If this is testing a single bit, we can optimize the test. */
6991 {
7000 /* First, see if we can fold the single bit test into a sign-bit
7001 test. */
7003 result_type);
7007 /* Otherwise we have (A & C) != 0 where C is a single bit,
7008 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7009 Similarly for (A & C) == 0. */
7011 /* If INNER is a right shift of a constant and it plus BITNUM does
7012 not overflow, adjust BITNUM and INNER. */
7019 {
7022 }
7024 /* If we are going to be able to omit the AND below, we must do our
7025 operations as unsigned. If we must use the AND, we have a choice.
7026 Normally unsigned is faster, but for some machines signed is. */
7027 #ifdef LOAD_EXTEND_OP
7030 #else
7032 #endif
7048 /* Put the AND last so it can combine with more things. */
7051 /* Make sure to return the proper type. */
7055 }
7057 }
7059 /* Check whether we are allowed to reorder operands arg0 and arg1,
7060 such that the evaluation of arg1 occurs before arg0. */
7062 static bool
7064 {
7071 }
7073 /* Test whether it is preferable two swap two operands, ARG0 and
7074 ARG1, for example because ARG0 is an integer constant and ARG1
7075 isn't. If REORDER is true, only recommend swapping if we can
7076 evaluate the operands in reverse order. */
7078 bool
7080 {
7116 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7117 for commutative and comparison operators. Ensuring a canonical
7118 form allows the optimizers to find additional redundancies without
7119 having to explicitly check for both orderings. */
7125 /* Put SSA_NAMEs last. */
7131 /* Put variables last. */
7138 }
7140 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7141 ARG0 is extended to a wider type. */
7143 static tree
7145 {
7147 tree arg1_unw;
7156 #ifdef HAVE_canonicalize_funcptr_for_compare
7157 /* Disable this optimization if we're casting a function pointer
7158 type on targets that require function pointer canonicalization. */
7163 #endif
7170 /* If possible, express the comparison in the shorter mode. */
7190 /* If we are comparing with the integer that does not fit into the range
7191 of the shorter type, the result is known. */
7202 {
7229 }
7232 }
7234 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7235 ARG0 just the signedness is changed. */
7237 static tree
7240 {
7241 tree arg0_inner;
7251 #ifdef HAVE_canonicalize_funcptr_for_compare
7252 /* Disable this optimization if we're casting a function pointer
7253 type on targets that require function pointer canonicalization. */
7258 #endif
7278 else
7282 }
7284 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7285 step of the array. Reconstructs s and delta in the case of s * delta
7286 being an integer constant (and thus already folded).
7287 ADDR is the address. MULT is the multiplicative expression.
7288 If the function succeeds, the new address expression is returned. Otherwise
7289 NULL_TREE is returned. */
7291 static tree
7293 {
7297 tree itype;
7300 /* Strip the nops that might be added when converting op1 to sizetype. */
7303 /* Canonicalize op1 into a possibly non-constant delta
7304 and an INTEGER_CST s. */
7306 {
7313 {
7316 }
7318 {
7321 }
7322 else
7324 }
7326 {
7329 }
7330 else
7331 {
7332 /* Simulate we are delta * 1. */
7335 }
7338 {
7340 {
7341 /* Remember if this was a multi-dimensional array. */
7354 {
7357 }
7358 else
7359 {
7360 /* Try if delta is a multiple of step. */
7365 }
7367 /* Only fold here if we can verify we do not overflow one
7368 dimension of a multi-dimensional array. */
7370 {
7371 tree tmp;
7387 }
7390 }
7391 else
7396 }
7398 /* We found the suitable array reference. So copy everything up to it,
7399 and replace the index. */
7406 {
7410 }
7418 }
7421 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7422 means A >= Y && A != MAX, but in this case we know that
7423 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7425 static tree
7427 {
7434 else
7443 {
7446 }
7448 {
7451 }
7452 else
7459 {
7460 /* Convert the pointer types into integer before taking the difference. */
7464 }
7465 else
7472 }
7474 /* Fold a sum or difference of at least one multiplication.
7475 Returns the folded tree or NULL if no simplification could be made. */
7477 static tree
7479 {
7483 /* (A * C) +- (B * C) -> (A+-B) * C.
7484 (A * C) +- A -> A * (C+-1).
7485 We are most concerned about the case where C is a constant,
7486 but other combinations show up during loop reduction. Since
7487 it is not difficult, try all four possibilities. */
7490 {
7493 }
7495 {
7498 }
7499 else
7500 {
7501 /* We cannot generate constant 1 for fract. */
7506 }
7508 {
7511 }
7513 {
7515 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7516 the purpose of this canonicalization. */
7520 {
7523 }
7524 else
7526 }
7527 else
7528 {
7529 /* We cannot generate constant 1 for fract. */
7534 }
7546 /* No identical multiplicands; see if we can find a common
7547 power-of-two factor in non-power-of-two multiplies. This
7548 can help in multi-dimensional array access. */
7551 {
7554 tree maybe_same;
7558 /* Move min of absolute values to int11. */
7561 {
7566 }
7567 else
7571 /* The remainder should not be a constant, otherwise we
7572 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7573 increased the number of multiplications necessary. */
7575 {
7583 }
7584 }
7594 }
7596 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7597 specified by EXPR into the buffer PTR of length LEN bytes.
7598 Return the number of bytes placed in the buffer, or zero
7599 upon failure. */
7601 static int
7603 {
7614 {
7618 else
7623 {
7630 else
7632 }
7633 else
7636 }
7638 }
7641 /* Subroutine of native_encode_expr. Encode the REAL_CST
7642 specified by EXPR into the buffer PTR of length LEN bytes.
7643 Return the number of bytes placed in the buffer, or zero
7644 upon failure. */
7646 static int
7648 {
7654 /* There are always 32 bits in each long, no matter the size of
7655 the hosts long. We handle floating point representations with
7656 up to 192 bits. */
7667 {
7672 {
7679 else
7681 }
7682 else
7685 }
7687 }
7689 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7690 specified by EXPR into the buffer PTR of length LEN bytes.
7691 Return the number of bytes placed in the buffer, or zero
7692 upon failure. */
7694 static int
7696 {
7698 tree part;
7709 }
7712 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7713 specified by EXPR into the buffer PTR of length LEN bytes.
7714 Return the number of bytes placed in the buffer, or zero
7715 upon failure. */
7717 static int
7719 {
7729 {
7731 {
7734 }
7735 else
7739 {
7742 }
7743 else
7744 {
7748 }
7750 }
7752 }
7755 /* Subroutine of native_encode_expr. Encode the STRING_CST
7756 specified by EXPR into the buffer PTR of length LEN bytes.
7757 Return the number of bytes placed in the buffer, or zero
7758 upon failure. */
7760 static int
7762 {
7764 HOST_WIDE_INT total_bytes;
7775 {
7779 }
7780 else
7783 }
7786 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7787 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7788 buffer PTR of length LEN bytes. Return the number of bytes
7789 placed in the buffer, or zero upon failure. */
7791 int
7793 {
7795 {
7813 }
7814 }
7817 /* Subroutine of native_interpret_expr. Interpret the contents of
7818 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7819 If the buffer cannot be interpreted, return NULL_TREE. */
7821 static tree
7823 {
7837 {
7840 {
7847 else
7849 }
7850 else
7856 else
7859 }
7862 }
7865 /* Subroutine of native_interpret_expr. Interpret the contents of
7866 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7867 If the buffer cannot be interpreted, return NULL_TREE. */
7869 static tree
7871 {
7876 /* There are always 32 bits in each long, no matter the size of
7877 the hosts long. We handle floating point representations with
7878 up to 192 bits. */
7879 REAL_VALUE_TYPE r;
7890 {
7893 {
7900 else
7902 }
7903 else
7908 }
7912 }
7915 /* Subroutine of native_interpret_expr. Interpret the contents of
7916 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7917 If the buffer cannot be interpreted, return NULL_TREE. */
7919 static tree
7921 {
7936 }
7939 /* Subroutine of native_interpret_expr. Interpret the contents of
7940 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7941 If the buffer cannot be interpreted, return NULL_TREE. */
7943 static tree
7945 {
7957 {
7962 }
7964 }
7967 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7968 the buffer PTR of length LEN as a constant of type TYPE. For
7969 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7970 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7971 return NULL_TREE. */
7973 tree
7975 {
7977 {
7994 }
7995 }
7998 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7999 TYPE at compile-time. If we're unable to perform the conversion
8000 return NULL_TREE. */
8002 static tree
8004 {
8005 /* We support up to 512-bit values (for V8DFmode). */
8009 /* Check that the host and target are sane. */
8018 }
8020 /* Build an expression for the address of T. Folds away INDIRECT_REF
8021 to avoid confusing the gimplify process. */
8023 tree
8025 {
8026 /* The size of the object is not relevant when talking about its address. */
8030 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8033 {
8038 }
8040 {
8045 }
8046 else
8050 }
8052 /* Build an expression for the address of T. */
8054 tree
8056 {
8060 }
8062 /* Fold a unary expression of code CODE and type TYPE with operand
8063 OP0. Return the folded expression if folding is successful.
8064 Otherwise, return NULL_TREE. */
8066 tree
8068 {
8069 tree tem;
8070 tree arg0;
8078 {
8081 {
8082 /* Don't use STRIP_NOPS, because signedness of argument type
8083 matters. */
8085 }
8086 else
8087 {
8088 /* Strip any conversions that don't change the mode. This
8089 is safe for every expression, except for a comparison
8090 expression because its signedness is derived from its
8091 operands.
8093 Note that this is done as an internal manipulation within
8094 the constant folder, in order to find the simplest
8095 representation of the arguments so that their form can be
8096 studied. In any cases, the appropriate type conversions
8097 should be put back in the tree that will get out of the
8098 constant folder. */
8100 }
8101 }
8104 {
8111 {
8123 /* If this was a conversion, and all we did was to move into
8124 inside the COND_EXPR, bring it back out. But leave it if
8125 it is a conversion from integer to integer and the
8126 result precision is no wider than a word since such a
8127 conversion is cheap and may be optimized away by combine,
8128 while it couldn't if it were outside the COND_EXPR. Then return
8129 so we don't get into an infinite recursion loop taking the
8130 conversion out and then back in. */
8142 && (INTEGRAL_TYPE_P
8154 }
8156 {
8158 {
8162 }
8166 integer_one_node),
8168 integer_zero_node));
8169 }
8170 }
8173 {
8175 /* Re-association barriers around constants and other re-association
8176 barriers can be removed. */
8182 CASE_CONVERT:
8188 /* If we have (type) (a CMP b) and type is an integral type, return
8189 new expression involving the new type. */
8194 /* Handle cases of two conversions in a row. */
8196 {
8218 /* In addition to the cases of two conversions in a row
8219 handled below, if we are converting something to its own
8220 type via an object of identical or wider precision, neither
8221 conversion is needed. */
8228 /* Likewise, if the intermediate and initial types are either both
8229 float or both integer, we don't need the middle conversion if the
8230 former is wider than the latter and doesn't change the signedness
8231 (for integers). Avoid this if the final type is a pointer since
8232 then we sometimes need the middle conversion. Likewise if the
8233 final type has a precision not equal to the size of its mode. */
8242 && ! final_ptr
8246 /* If we have a sign-extension of a zero-extended value, we can
8247 replace that by a single zero-extension. */
8253 /* Two conversions in a row are not needed unless:
8254 - some conversion is floating-point (overstrict for now), or
8255 - some conversion is a vector (overstrict for now), or
8256 - the intermediate type is narrower than both initial and
8257 final, or
8258 - the intermediate type and innermost type differ in signedness,
8259 and the outermost type is wider than the intermediate, or
8260 - the initial type is a pointer type and the precisions of the
8261 intermediate and final types differ, or
8262 - the final type is a pointer type and the precisions of the
8263 initial and intermediate types differ. */
8277 }
8279 /* Handle (T *)&A.B.C for A being of type T and B and C
8280 living at offset zero. This occurs frequently in
8281 C++ upcasting and then accessing the base. */
8285 {
8287 tree offset;
8293 /* If the reference was to a (constant) zero offset, we can use
8294 the address of the base if it has the same base type
8295 as the result type. */
8300 }
8304 /* Detect assigning a bitfield. */
8306 && DECL_BIT_FIELD
8308 {
8309 /* Don't leave an assignment inside a conversion
8310 unless assigning a bitfield. */
8312 /* First do the assignment, then return converted constant. */
8317 }
8319 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8320 constants (if x has signed type, the sign bit cannot be set
8321 in c). This folds extension into the BIT_AND_EXPR.
8322 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8323 very likely don't have maximal range for their precision and this
8324 transformation effectively doesn't preserve non-maximal ranges. */
8328 {
8339 <= HOST_BITS_PER_WIDE_INT
8341 {
8348 #ifdef LOAD_EXTEND_OP
8350 && !flag_syntax_only
8353 {
8357 }
8358 #endif
8359 }
8361 {
8367 }
8368 }
8370 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type. */
8373 {
8379 }
8381 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8382 of the same precision, and X is an integer type not narrower than
8383 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8389 {
8394 }
8396 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8397 type of X and Y (integer types only). */
8402 {
8403 /* Be careful to fall back to MULT_EXPR from MULTNV_EXPR. */
8409 }
8424 /* For integral conversions with the same precision or pointer
8425 conversions use a NOP_EXPR instead. */
8433 /* Strip inner integral conversions that do not change the precision. */
8457 /* Convert fabs((double)float) into (double)fabsf(float). */
8460 {
8465 targ0));
8466 }
8467 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8473 /* Strip sign ops from argument. */
8475 {
8479 }
8486 {
8491 }
8493 {
8498 }
8508 /* Convert ~ (-A) to A - 1. */
8513 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8521 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8534 /* Perform BIT_NOT_EXPR on each element individually. */
8536 {
8541 {
8543 {
8549 }
8550 else
8553 }
8556 }
8561 /* The argument to invert_truthvalue must have Boolean type. */
8565 /* Note that the operand of this must be an int
8566 and its values must be 0 or 1.
8567 ("true" is a fixed value perhaps depending on the language,
8568 but we don't handle values other than 1 correctly yet.) */
8583 {
8591 }
8593 {
8597 }
8599 {
8603 {
8612 }
8613 }
8625 {
8633 }
8635 {
8639 }
8641 {
8645 {
8654 }
8655 }
8661 }
8664 /* If the operation was a conversion do _not_ mark a resulting constant
8665 with TREE_OVERFLOW if the original constant was not. These conversions
8666 have implementation defined behavior and retaining the TREE_OVERFLOW
8667 flag here would confuse later passes such as VRP. */
8668 tree
8670 {
8679 }
8681 /* Fold a binary expression of code CODE and type TYPE with operands
8682 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8683 Return the folded expression if folding is successful. Otherwise,
8684 return NULL_TREE. */
8686 static tree
8688 {
8695 else
8698 /* MIN (MAX (a, b), b) == b. */
8703 /* MIN (MAX (b, a), b) == b. */
8709 /* MIN (a, MAX (a, b)) == a. */
8715 /* MIN (a, MAX (b, a)) == a. */
8722 }
8724 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8725 by changing CODE to reduce the magnitude of constants involved in
8726 ARG0 of the comparison.
8727 Returns a canonicalized comparison tree if a simplification was
8728 possible, otherwise returns NULL_TREE.
8729 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8730 valid if signed overflow is undefined. */
8732 static tree
8736 {
8742 /* Match A +- CST code arg1 and CST code arg1. We can change the
8743 first form only if the operation does not wrap. */
8745 but that causes problems elsewhere. */
8752 /* Identify the constant in arg0 and its sign. */
8755 else
8759 /* Overflowed constants and zero will cause problems. */
8764 /* See if we can reduce the magnitude of the constant in
8765 arg0 by changing the comparison code. */
8767 {
8768 /* CST <= arg1 -> CST-1 < arg1. */
8771 /* -CST < arg1 -> -CST-1 <= arg1. */
8774 /* CST > arg1 -> CST-1 >= arg1. */
8777 /* -CST >= arg1 -> -CST-1 > arg1. */
8780 else
8782 /* arg1 code' CST' might be more canonical. */
8784 }
8785 else
8786 {
8787 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8791 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8795 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8799 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8803 else
8807 }
8809 /* Now build the constant reduced in magnitude. But not if that
8810 would produce one outside of its types range. */
8818 /* We cannot swap the comparison here as that would cause us to
8819 endlessly recurse. */
8824 /* If A - CST didn't overflow so does A - (CST - 1). So it is safe
8825 to keep the *NV_EXPR variants. */
8829 /* If swapping might yield to a more canonical form, do so. */
8832 else
8834 }
8836 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8837 overflow further. Try to decrease the magnitude of constants involved
8838 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8839 and put sole constants at the second argument position.
8840 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8842 static tree
8845 {
8846 tree t;
8851 /* Try canonicalization by simplifying arg0. */
8856 {
8860 }
8862 /* Try canonicalization by simplifying arg1 using the swapped
8863 comparison. */
8871 }
8873 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8874 space. This is used to avoid issuing overflow warnings for
8875 expressions like &p->x which can not wrap. */
8877 static bool
8879 {
8890 {
8893 }
8896 else
8897 {
8900 }
8915 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8916 array. */
8918 {
8919 HOST_WIDE_INT base_size;
8924 }
8927 }
8929 /* Subroutine of fold_binary. This routine performs all of the
8930 transformations that are common to the equality/inequality
8931 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8932 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8933 fold_binary should call fold_binary. Fold a comparison with
8934 tree code CODE and type TYPE with operands OP0 and OP1. Return
8935 the folded comparison or NULL_TREE. */
8937 static tree
8939 {
8952 /* If one arg is a real or integer constant, put it last. */
8956 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1
8957 if the original addition does not overflow. */
8961 {
8965 tree lhs;
8968 HOST_WIDE_INT hi;
8977 /* If there was overflow on combining the two constants we have to
8978 flip the comparison code. */
8985 "when changing X +- C1 cmp C2 to "
8987 WARN_STRICT_OVERFLOW_COMPARISON);
8989 }
8991 /* For comparisons of pointers we can decompose it to a compile time
8992 comparison of the base objects and the offsets into the object.
8993 This requires at least one operand being an ADDR_EXPR or a
8994 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9000 {
9008 /* Get base and offset for the access. Strip ADDR_EXPR for
9009 get_inner_reference, but put it back by stripping INDIRECT_REF
9010 off the base object if possible. indirect_baseN will be true
9011 if baseN is not an address but refers to the object itself. */
9014 {
9020 else
9022 }
9024 {
9029 }
9033 {
9039 else
9041 }
9043 {
9048 }
9050 /* If we have equivalent bases we might be able to simplify. */
9053 {
9054 /* We can fold this expression to a constant if the non-constant
9055 offset parts are equal. */
9062 {
9069 "occur when comparing P +- C1 with "
9071 WARN_STRICT_OVERFLOW_CONDITIONAL);
9074 {
9088 }
9089 }
9090 /* We can simplify the comparison to a comparison of the variable
9091 offset parts if the constant offset parts are equal.
9092 Be careful to use signed size type here because otherwise we
9093 mess with array offsets in the wrong way. This is possible
9094 because pointer arithmetic is restricted to retain within an
9095 object and overflow on pointer differences is undefined as of
9096 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9100 {
9101 tree signed_size_type_node;
9104 /* By converting to signed size type we cover middle-end pointer
9105 arithmetic which operates on unsigned pointer types of size
9106 type size and ARRAY_REF offsets which are properly sign or
9107 zero extended from their type in case it is narrower than
9108 size type. */
9111 else
9115 else
9123 "occur when comparing P +- C1 with "
9125 WARN_STRICT_OVERFLOW_COMPARISON);
9128 }
9129 }
9130 /* For non-equal bases we can simplify if they are addresses
9131 of local binding decls or constants. */
9133 /* We know that !operand_equal_p (base0, base1, 0)
9134 because the if condition was false. But make
9135 sure two decls are not the same. */
9149 {
9154 }
9155 /* For equal offsets we can simplify to a comparison of the
9156 base addresses. */
9158 && (indirect_base0
9160 && (indirect_base1
9165 {
9171 }
9172 }
9174 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9175 X CMP Y +- C2 +- C1 if X +- C1 does not overflow.. This is then
9176 valid if the resulting offset is smaller in absolute value than the
9177 original one. */
9184 {
9189 tree cst;
9191 HOST_WIDE_INT hi;
9194 "occur when combining constants around "
9197 /* Put the constant on the side where it doesn't overflow and is
9198 of lower absolute value than before if the operation on
9199 the other side doesn't overflow. */
9201 {
9210 {
9214 variable1,
9218 }
9219 }
9222 {
9231 {
9238 variable2);
9239 }
9240 }
9241 }
9243 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9244 signed arithmetic case. That form is created by the compiler
9245 often enough for folding it to be of value. One example is in
9246 computing loop trip counts after Operator Strength Reduction. */
9252 {
9261 "eliminating multiplication in comparison "
9263 WARN_STRICT_OVERFLOW_COMPARISON);
9265 /* If const1 is negative we swap the sense of the comparison. */
9270 }
9277 {
9285 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9290 /* (-a) CMP (-b) -> b CMP a */
9297 {
9298 REAL_VALUE_TYPE cst;
9301 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9308 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9309 /* a CMP (-0) -> a CMP 0 */
9314 /* x != NaN is always true, other ops are always false. */
9317 {
9320 }
9322 /* Fold comparisons against infinity. */
9325 {
9329 }
9330 }
9332 /* If this is a comparison of a real constant with a PLUS_EXPR
9333 or a MINUS_EXPR of a real constant, we can convert it into a
9334 comparison with a revised real constant as long as no overflow
9335 occurs when unsafe_math_optimizations are enabled. */
9347 /* Likewise, we can simplify a comparison of a real constant with
9348 a MINUS_EXPR whose first operand is also a real constant, i.e.
9349 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9350 floating-point types only if -fassociative-math is set. */
9361 /* Fold comparisons against built-in math functions. */
9363 && flag_unsafe_math_optimizations
9365 {
9369 {
9373 }
9374 }
9375 }
9379 {
9380 /* If we are widening one operand of an integer comparison,
9381 see if the other operand is similarly being widened. Perhaps we
9382 can do the comparison in the narrower type. */
9387 /* Or if we are changing signedness. */
9391 }
9393 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9394 constant, we can simplify it. */
9399 {
9403 }
9405 /* Simplify comparison of something with itself. (For IEEE
9406 floating-point, we can only do some of these simplifications.) */
9408 {
9410 {
9425 /* For NE, we can only do this simplification if integer
9426 or we don't honor IEEE floating point NaNs. */
9430 /* ... fall through ... */
9436 }
9437 }
9439 /* If we are comparing an expression that just has comparisons
9440 of two integer values, arithmetic expressions of those comparisons,
9441 and constants, we can simplify it. There are only three cases
9442 to check: the two values can either be equal, the first can be
9443 greater, or the second can be greater. Fold the expression for
9444 those three values. Since each value must be 0 or 1, we have
9445 eight possibilities, each of which corresponds to the constant 0
9446 or 1 or one of the six possible comparisons.
9448 This handles common cases like (a > b) == 0 but also handles
9449 expressions like ((x > y) - (y > x)) > 0, which supposedly
9450 occur in macroized code. */
9453 {
9458 /* Don't handle degenerate cases here; they should already
9459 have been handled anyway. */
9468 {
9472 /* We can't just pass T to eval_subst in case cval1 or cval2
9473 was the same as ARG1. */
9475 tree high_result
9479 arg1);
9480 tree equal_result
9484 arg1);
9485 tree low_result
9489 arg1);
9491 /* All three of these results should be 0 or 1. Confirm they are.
9492 Then use those values to select the proper code to use. */
9497 {
9498 /* Make a 3-bit mask with the high-order bit being the
9499 value for `>', the next for '=', and the low for '<'. */
9503 {
9505 /* Always false. */
9526 /* Always true. */
9528 }
9533 }
9534 }
9535 }
9537 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9538 into a single range test. */
9546 {
9550 }
9552 /* Fold ~X op ~Y as Y op X. */
9555 {
9560 }
9562 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9565 {
9571 }
9574 }
9577 /* Subroutine of fold_binary. Optimize complex multiplications of the
9578 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9579 argument EXPR represents the expression "z" of type TYPE. */
9581 static tree
9583 {
9588 {
9591 }
9593 {
9596 }
9597 else
9598 {
9602 }
9611 }
9614 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9615 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9616 guarantees that P and N have the same least significant log2(M) bits.
9617 N is not otherwise constrained. In particular, N is not normalized to
9618 0 <= N < M as is common. In general, the precise value of P is unknown.
9619 M is chosen as large as possible such that constant N can be determined.
9621 Returns M and sets *RESIDUE to N.
9623 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9624 account. This is not always possible due to PR 35705.
9625 */
9627 static unsigned HOST_WIDE_INT
9630 {
9637 {
9640 {
9642 tree offset;
9650 {
9653 else
9654 /* We don't handle more complicated offset expressions. */
9656 }
9657 }
9662 }
9664 {
9672 allow_func_align);
9678 {
9681 }
9683 {
9686 {
9689 /* Compute the greatest power-of-2 divisor of op1. */
9693 /* If align is non-zero and less than *modulus, replace
9694 *modulus with align., If align is 0, then either op1 is 0
9695 or the greatest power-of-2 divisor of op1 doesn't fit in an
9696 unsigned HOST_WIDE_INT. In either case, no additional
9697 constraint is imposed. */
9702 }
9703 }
9704 }
9706 /* If we get here, we were unable to determine anything useful about the
9707 expression. */
9709 }
9712 /* Fold a binary expression of code CODE and type TYPE with operands
9713 OP0 and OP1. Return the folded expression if folding is
9714 successful. Otherwise, return NULL_TREE. */
9716 tree
9718 {
9732 /* Strip any conversions that don't change the mode. This is
9733 safe for every expression, except for a comparison expression
9734 because its signedness is derived from its operands. So, in
9735 the latter case, only strip conversions that don't change the
9736 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9737 preserved.
9739 Note that this is done as an internal manipulation within the
9740 constant folder, in order to find the simplest representation
9741 of the arguments so that their form can be studied. In any
9742 cases, the appropriate type conversions should be put back in
9743 the tree that will get out of the constant folder. */
9746 {
9749 }
9750 else
9751 {
9754 }
9756 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9757 constant but we can't do arithmetic on them. */
9764 {
9766 {
9767 /* Make sure type and arg0 have the same saturating flag. */
9771 }
9774 else
9778 {
9782 }
9783 }
9785 /* If this is a commutative operation, and ARG0 is a constant, move it
9786 to ARG1 to reduce the number of tests below. */
9791 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9793 First check for cases where an arithmetic operation is applied to a
9794 compound, conditional, or comparison operation. Push the arithmetic
9795 operation inside the compound or conditional to see if any folding
9796 can then be done. Convert comparison to conditional for this purpose.
9797 The also optimizes non-constant cases that used to be done in
9798 expand_expr.
9800 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9801 one of the operands is a comparison and the other is a comparison, a
9802 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9803 code below would make the expression more complex. Change it to a
9804 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9805 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9817 {
9821 boolean_type_node,
9829 }
9833 {
9839 op1));
9848 {
9854 }
9857 {
9863 }
9864 }
9867 {
9870 /* 0 +p index -> (type)index */
9874 /* PTR +p 0 -> PTR */
9878 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9885 /* index +p PTR -> PTR +p index */
9892 /* (PTR +p B) +p A -> PTR +p (B + A) */
9894 {
9895 tree inner;
9907 }
9909 /* PTR_CST +p CST -> CST1 */
9913 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9914 of the array. Loop optimizer sometimes produce this type of
9915 expressions. */
9917 {
9921 }
9927 /* A + (-B) -> A - B */
9932 /* (-A) + B -> B - A */
9940 {
9941 /* Convert ~A + 1 to -A. */
9947 /* ~X + X is -1. */
9950 {
9955 {
9958 }
9959 }
9961 /* X + ~X is -1. */
9964 {
9969 {
9972 }
9973 }
9975 /* X + (X / CST) * -CST is X % CST. */
9980 {
9988 }
9989 }
9991 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9992 same or one. Make sure type is not saturating.
9993 fold_plusminus_mult_expr will re-associate. */
9998 {
10002 }
10005 {
10009 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10010 with a constant, and the two constants have no bits in common,
10011 we should treat this as a BIT_IOR_EXPR since this may produce more
10012 simplifications. */
10020 {
10023 }
10025 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10026 (plus (plus (mult) (mult)) (foo)) so that we can
10027 take advantage of the factoring cases below. */
10032 {
10038 else
10060 parg1)));
10061 }
10062 }
10063 else
10064 {
10065 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10069 /* Likewise if the operands are reversed. */
10073 /* Convert X + -C into X - C. */
10076 {
10082 }
10084 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10085 to __complex__ ( x, y ). This is not the same for SNaNs or
10086 if signed zeros are involved. */
10090 {
10097 {
10101 {
10107 }
10109 {
10115 }
10116 }
10117 }
10125 /* Convert x+x into x*2.0. */
10131 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10132 We associate floats only if the user has specified
10133 -fassociative-math. */
10137 {
10142 {
10143 tree tree0;
10146 }
10147 }
10148 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10149 We associate floats only if the user has specified
10150 -fassociative-math. */
10154 {
10159 {
10160 tree tree0;
10163 }
10164 }
10165 }
10167 /* Convert (T1)X + (T1)Y to (T1)(X + Y) if (T1)X is only
10168 a sign-change. */
10174 /* Do not expose arithmetic in Ada subtypes. */
10187 bit_rotate:
10188 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10189 is a rotate of A by C1 bits. */
10190 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10191 is a rotate of A by B bits. */
10192 {
10194 tree rtype;
10203 /* Only create rotates in complete modes. Other cases are not
10204 expanded properly. */
10206 {
10226 code0 == LSHIFT_EXPR
10229 {
10237 TYPE_PRECISION
10243 ? LROTATE_EXPR
10247 }
10249 {
10257 TYPE_PRECISION
10263 ? LROTATE_EXPR
10267 }
10268 }
10269 }
10271 associate:
10272 /* In most languages, can't associate operations on floats through
10273 parentheses. Rather than remember where the parentheses were, we
10274 don't associate floats at all, unless the user has specified
10275 -fassociative-math.
10276 And, we need to make sure type is not saturating. */
10280 {
10284 /* Split both trees into variables, constants, and literals. Then
10285 associate each group together, the constants with literals,
10286 then the result with variables. This increases the chances of
10287 literals being recombined later and of generating relocatable
10288 expressions for the sum of a constant and literal. */
10293 /* Only do something if we found more than two objects. Otherwise,
10294 nothing has changed and we risk infinite recursion. */
10299 {
10300 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10309 /* Preserve the MINUS_EXPR if the negative part of the literal is
10310 greater than the positive part. Otherwise, the multiplicative
10311 folding code (i.e extract_muldiv) may be fooled in case
10312 unsigned constants are subtracted, like in the following
10313 example: ((X*2 + 4) - 8U)/2. */
10315 {
10319 {
10323 }
10324 else
10325 {
10329 }
10330 }
10332 {
10337 else
10338 {
10344 }
10345 }
10350 }
10351 }
10357 /* Pointer simplifications for subtraction, simple reassociations. */
10359 {
10360 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10363 {
10371 }
10372 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming
10373 PTR0 - PTR1 simplifies. */
10375 {
10382 }
10383 }
10385 /* A - (-B) -> A + B */
10389 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10398 /* Convert -A - 1 to ~A. */
10407 /* Convert -1 - A to ~A. */
10413 /* X - (X / CST) * CST is X % CST. */
10426 {
10432 /* Fold A - (A & B) into ~B & A. */
10435 {
10437 {
10442 }
10444 {
10449 }
10450 }
10452 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10453 any power of 2 minus 1. */
10458 {
10464 {
10468 }
10469 }
10470 }
10472 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10476 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10477 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10478 (-ARG1 + ARG0) reduces to -ARG1. */
10482 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10483 __complex__ ( x, -y ). This is not the same for SNaNs or if
10484 signed zeros are involved. */
10488 {
10495 {
10499 {
10501 arg1r ? arg1r
10506 }
10508 {
10512 arg1i ? arg1i
10515 }
10516 }
10517 }
10519 /* Fold &x - &x. This can happen from &x.foo - &x.
10520 This is unsafe for certain floats even in non-IEEE formats.
10521 In IEEE, it is unsafe because it does wrong for NaNs.
10522 Also note that operand_equal_p is always false if an operand
10523 is volatile. */
10529 /* A - B -> A + (-B) if B is easily negatable. */
10531 /* Avoid negating constants if that would change overflow
10532 behavior. */
10537 /* Avoid this transformation if B is a positive REAL_CST. */
10541 {
10543 /* If the original subtraction is signed and did not overflow
10544 so does the new addition if the negation of arg1 does not
10545 overflow (which we know for constants only). */
10553 }
10555 /* Try folding difference of addresses. */
10556 {
10557 HOST_WIDE_INT diff;
10563 }
10565 /* Fold &a[i] - &a[j] to i-j. */
10570 {
10575 {
10583 }
10584 }
10587 && flag_unsafe_math_optimizations
10593 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10594 same or one. Make sure type is not saturating.
10595 fold_plusminus_mult_expr will re-associate. */
10600 {
10604 }
10606 /* Convert (T1)X - (T1)Y to (T1)(X - Y) if (T1)X is only
10607 a sign-change. */
10613 /* Do not expose arithmetic in Ada subtypes. */
10631 {
10636 /* Transform x * -1 into -x. Make sure to do the negation
10637 on the original operand with conversions not stripped
10638 because we can only strip non-sign-changing conversions. */
10641 }
10643 /* (-A) * (-B) -> A * B. */
10654 {
10655 /* Transform x * -C into -x * C if x is easily negatable. */
10664 /* (a * (1 << b)) is (a << b) */
10674 /* (A + A) * C -> A * 2 * C */
10689 {
10692 "occur when simplifying "
10694 WARN_STRICT_OVERFLOW_MISC);
10696 }
10698 /* Optimize z * conj(z) for integer complex numbers. */
10705 }
10706 else
10707 {
10708 /* Maybe fold x * 0 to 0. The expressions aren't the same
10709 when x is NaN, since x * 0 is also NaN. Nor are they the
10710 same in modes with signed zeros, since multiplying a
10711 negative value by 0 gives -0, not +0. */
10716 /* In IEEE floating point, x*1 is not equivalent to x for snans.
10717 Likewise for complex arithmetic with signed zeros. */
10724 /* Transform x * -1.0 into -x. */
10731 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10732 the result for floating point types due to rounding so it is applied
10733 only if -fassociative-math was specify. */
10738 {
10744 }
10746 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10748 {
10751 {
10754 }
10755 }
10757 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10758 This is not the same for NaNs or if signed zeros are
10759 involved. */
10765 {
10777 }
10779 /* Optimize z * conj(z) for floating point complex numbers.
10780 Guarded by flag_unsafe_math_optimizations as non-finite
10781 imaginary components don't produce scalar results. */
10792 {
10796 /* Optimizations of root(...)*root(...). */
10798 {
10803 /* Optimize sqrt(x)*sqrt(x) as x. */
10809 /* Optimize root(x)*root(y) as root(x*y). */
10813 }
10815 /* Optimize expN(x)*expN(y) as expN(x+y). */
10817 {
10823 }
10825 /* Optimizations of pow(...)*pow(...). */
10829 {
10835 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10837 {
10841 }
10843 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10845 {
10849 }
10850 }
10852 /* Optimize tan(x)*cos(x) as sin(x). */
10861 {
10866 }
10868 /* Optimize x*pow(x,c) as pow(x,c+1). */
10872 {
10878 {
10880 REAL_VALUE_TYPE c;
10881 tree arg;
10887 }
10888 }
10890 /* Optimize pow(x,c)*x as pow(x,c+1). */
10894 {
10900 {
10902 REAL_VALUE_TYPE c;
10903 tree arg;
10909 }
10910 }
10912 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10915 {
10919 {
10922 }
10923 }
10924 }
10925 }
10929 bit_ior:
10937 /* ~X | X is -1. */
10940 {
10944 }
10946 /* X | ~X is -1. */
10949 {
10953 }
10955 /* Canonicalize (X & C1) | C2. */
10959 {
10967 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10972 {
10976 }
10977 else
10978 {
10982 }
10984 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10989 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10990 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10991 mode which allows further optimizations. */
11001 {
11002 unsigned HOST_WIDE_INT mask
11006 {
11010 }
11011 }
11018 arg1);
11019 }
11021 /* (X & Y) | Y is (X, Y). */
11025 /* (X & Y) | X is (Y, X). */
11030 /* X | (X & Y) is (Y, X). */
11035 /* X | (Y & X) is (Y, X). */
11045 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11047 This results in more efficient code for machines without a NAND
11048 instruction. Combine will canonicalize to the first form
11049 which will allow use of NAND instructions provided by the
11050 backend if they exist. */
11053 {
11060 }
11062 /* See if this can be simplified into a rotate first. If that
11063 is unsuccessful continue in the association code. */
11074 /* ~X ^ X is -1. */
11077 {
11081 }
11083 /* X ^ ~X is -1. */
11086 {
11090 }
11092 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11093 with a constant, and the two constants have no bits in common,
11094 we should treat this as a BIT_IOR_EXPR since this may produce more
11095 simplifications. */
11103 {
11106 }
11108 /* (X | Y) ^ X -> Y & ~ X*/
11111 {
11114 arg1);
11118 }
11120 /* (Y | X) ^ X -> Y & ~ X*/
11123 {
11126 arg1);
11130 }
11132 /* X ^ (X | Y) -> Y & ~ X*/
11135 {
11138 arg0);
11142 }
11144 /* X ^ (Y | X) -> Y & ~ X*/
11147 {
11150 arg0);
11154 }
11156 /* Convert ~X ^ ~Y to X ^ Y. */
11163 /* Convert ~X ^ C to X ^ ~C. */
11170 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11177 /* Fold (X & Y) ^ Y as ~X & Y. */
11180 {
11185 }
11186 /* Fold (X & Y) ^ X as ~Y & X. */
11190 {
11195 }
11196 /* Fold X ^ (X & Y) as X & ~Y. */
11199 {
11204 }
11205 /* Fold X ^ (Y & X) as ~Y & X. */
11209 {
11214 }
11216 /* See if this can be simplified into a rotate first. If that
11217 is unsuccessful continue in the association code. */
11228 /* ~X & X is always zero. */
11233 /* X & ~X is always zero. */
11238 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11242 {
11250 }
11252 /* (X | Y) & Y is (X, Y). */
11256 /* (X | Y) & X is (Y, X). */
11261 /* X & (X | Y) is (Y, X). */
11266 /* X & (Y | X) is (Y, X). */
11272 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11276 {
11282 }
11283 /* Fold ~X & 1 as (X & 1) == 0. */
11286 {
11292 }
11294 /* Fold (X ^ Y) & Y as ~X & Y. */
11297 {
11302 }
11303 /* Fold (X ^ Y) & X as ~Y & X. */
11307 {
11312 }
11313 /* Fold X & (X ^ Y) as X & ~Y. */
11316 {
11321 }
11322 /* Fold X & (Y ^ X) as ~Y & X. */
11326 {
11331 }
11336 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11339 {
11340 unsigned int prec
11347 }
11349 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11351 This results in more efficient code for machines without a NOR
11352 instruction. Combine will canonicalize to the first form
11353 which will allow use of NOR instructions provided by the
11354 backend if they exist. */
11357 {
11364 }
11366 /* If arg0 is derived from the address of an object or function, we may
11367 be able to fold this expression using the object or function's
11368 alignment. */
11370 {
11377 /* This works because modulus is a power of 2. If this weren't the
11378 case, we'd have to replace it by its greatest power-of-2
11379 divisor: modulus & -modulus. */
11382 }
11384 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11385 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11386 if the new mask might be further optimized. */
11395 {
11397 unsigned HOST_WIDE_INT mask
11407 {
11410 /* See if more bits can be proven as zero because of
11411 zero extension. */
11414 {
11419 {
11421 /* See if we can shorten the right shift. */
11424 }
11425 }
11429 /* For arithmetic shift if sign bit could be set, zerobits
11430 can contain actually sign bits, so no transformation is
11431 possible, unless MASK masks them all away. In that
11432 case the shift needs to be converted into logical shift. */
11435 {
11438 else
11440 }
11441 }
11443 /* ((X << 16) & 0xff00) is (X, 0). */
11449 {
11452 /* Only do the transformation if NEWMASK is some integer
11453 mode's mask. */
11460 {
11461 tree newmaskt;
11464 {
11470 }
11471 else
11476 }
11477 }
11478 }
11483 /* Don't touch a floating-point divide by zero unless the mode
11484 of the constant can represent infinity. */
11490 /* Optimize A / A to 1.0 if we don't care about
11491 NaNs or Infinities. Skip the transformation
11492 for non-real operands. */
11497 {
11501 }
11503 /* The complex version of the above A / A optimization. */
11506 {
11510 {
11512 /* omit_two_operands will call fold_convert for us. */
11514 }
11515 }
11517 /* (-A) / (-B) -> A / B */
11527 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11532 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11537 /* If ARG1 is a constant, we can convert this to a multiply by the
11538 reciprocal. This does not have the same rounding properties,
11539 so only do this if -freciprocal-math. We can actually
11540 always safely do it if ARG1 is a power of two, but it's hard to
11541 tell if it is or not in a portable manner. */
11543 {
11548 /* Find the reciprocal if optimizing and the result is exact. */
11550 {
11551 REAL_VALUE_TYPE r;
11554 {
11558 }
11559 }
11560 }
11561 /* Convert A/B/C to A/(B*C). */
11568 /* Convert A/(B/C) to (A/B)*C. */
11576 /* Convert C1/(X*C2) into (C1/C2)/X. */
11581 {
11587 }
11590 {
11594 /* Optimize sin(x)/cos(x) as tan(x). */
11600 {
11605 }
11607 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11613 {
11617 {
11621 }
11622 }
11624 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11625 NaNs or Infinities. */
11629 {
11636 {
11641 }
11642 }
11644 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11645 NaNs or Infinities. */
11649 {
11656 {
11660 {
11664 tmp);
11665 }
11666 }
11667 }
11669 /* Optimize pow(x,c)/x as pow(x,c-1). */
11673 {
11679 {
11681 REAL_VALUE_TYPE c;
11682 tree arg;
11688 }
11689 }
11691 /* Optimize a/root(b/c) into a*root(c/b). */
11693 {
11697 {
11706 }
11707 }
11709 /* Optimize x/expN(y) into x*expN(-y). */
11711 {
11716 }
11718 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11722 {
11729 }
11730 }
11735 /* Simplify A / (B << N) where A and B are positive and B is
11736 a power of 2, to A >> (N + log2(B)). */
11741 {
11744 {
11751 WARN_STRICT_OVERFLOW_MISC);
11757 }
11758 }
11760 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11761 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11767 /* Fall thru */
11776 /* X / -1 is -X. */
11783 /* Convert -A / -B to A / B when the type is signed and overflow is
11784 undefined. */
11788 {
11791 "when distributing negation across "
11793 WARN_STRICT_OVERFLOW_MISC);
11797 }
11801 {
11804 "when distributing negation across "
11806 WARN_STRICT_OVERFLOW_MISC);
11810 }
11812 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11813 operation, EXACT_DIV_EXPR.
11815 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11816 At one time others generated faster code, it's not clear if they do
11817 after the last round to changes to the DIV code in expmed.c. */
11826 {
11830 WARN_STRICT_OVERFLOW_MISC);
11832 }
11840 /* X % 1 is always zero, but be sure to preserve any side
11841 effects in X. */
11845 /* X % 0, return X % 0 unchanged so that we can get the
11846 proper warnings and errors. */
11850 /* 0 % X is always zero, but be sure to preserve any side
11851 effects in X. Place this after checking for X == 0. */
11855 /* X % -1 is zero. */
11862 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11863 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11868 {
11870 /* Also optimize A % (C << N) where C is a power of 2,
11871 to A & ((C << N) - 1). */
11876 {
11881 "occur when simplifying "
11883 WARN_STRICT_OVERFLOW_MISC);
11887 }
11888 }
11890 /* X % -C is the same as X % C. */
11897 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11902 /* X % -Y is the same as X % Y. */
11913 {
11917 WARN_STRICT_OVERFLOW_MISC);
11919 }
11930 /* Optimize -1 >> x for arithmetic right shifts. */
11934 /* ... fall through ... */
11937 shift:
11943 /* Since negative shift count is not well-defined,
11944 don't try to compute it in the compiler. */
11948 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11953 {
11957 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11958 being well defined. */
11960 {
11966 else
11968 }
11972 }
11974 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11975 into x & ((unsigned)-1 >> c) for unsigned types. */
11983 {
11986 tree lshift;
11987 tree arg00;
11990 {
11997 }
11998 }
12000 /* Rewrite an LROTATE_EXPR by a constant into an
12001 RROTATE_EXPR by a new constant. */
12003 {
12008 }
12010 /* If we have a rotate of a bit operation with the rotate count and
12011 the second operand of the bit operation both constant,
12012 permute the two operations. */
12024 /* Two consecutive rotates adding up to the precision of the
12025 type can be ignored. */
12036 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12037 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12038 if the latter can be further optimized. */
12043 {
12046 arg1);
12049 arg1);
12053 }
12081 /* Note that the operands of this must be ints
12082 and their values must be 0 or 1.
12083 ("true" is a fixed value perhaps depending on the language.) */
12084 /* If first arg is constant zero, return it. */
12088 /* If either arg is constant true, drop it. */
12092 /* Preserve sequence points. */
12095 /* If second arg is constant zero, result is zero, but first arg
12096 must be evaluated. */
12099 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12100 case will be handled here. */
12104 /* !X && X is always false. */
12108 /* X && !X is always false. */
12113 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12114 means A >= Y && A != MAX, but in this case we know that
12115 A < X <= MAX. */
12119 {
12127 }
12129 truth_andor:
12130 /* We only do these simplifications if we are optimizing. */
12134 /* Check for things like (A || B) && (A || C). We can convert this
12135 to A || (B && C). Note that either operator can be any of the four
12136 truth and/or operations and the transformation will still be
12137 valid. Also note that we only care about order for the
12138 ANDIF and ORIF operators. If B contains side effects, this
12139 might change the truth-value of A. */
12146 {
12166 /* This case if tricky because we must either have commutative
12167 operators or else A10 must not have side-effects. */
12173 a01);
12174 }
12176 /* See if we can build a range comparison. */
12180 /* Check for the possibility of merging component references. If our
12181 lhs is another similar operation, try to merge its rhs with our
12182 rhs. Then try to merge our lhs and rhs. */
12194 /* Note that the operands of this must be ints
12195 and their values must be 0 or true.
12196 ("true" is a fixed value perhaps depending on the language.) */
12197 /* If first arg is constant true, return it. */
12201 /* If either arg is constant zero, drop it. */
12205 /* Preserve sequence points. */
12208 /* If second arg is constant true, result is true, but we must
12209 evaluate first arg. */
12212 /* Likewise for first arg, but note this only occurs here for
12213 TRUTH_OR_EXPR. */
12217 /* !X || X is always true. */
12221 /* X || !X is always true. */
12229 /* If the second arg is constant zero, drop it. */
12232 /* If the second arg is constant true, this is a logical inversion. */
12234 {
12235 /* Only call invert_truthvalue if operand is a truth value. */
12238 else
12241 }
12242 /* Identical arguments cancel to zero. */
12246 /* !X ^ X is always true. */
12251 /* X ^ !X is always true. */
12264 /* bool_var != 0 becomes bool_var. */
12269 /* bool_var == 1 becomes bool_var. */
12274 /* bool_var != 1 becomes !bool_var. */
12279 /* bool_var == 0 becomes !bool_var. */
12284 /* If this is an equality comparison of the address of two non-weak,
12285 unaliased symbols neither of which are extern (since we do not
12286 have access to attributes for externs), then we know the result. */
12299 {
12300 /* We know that we're looking at the address of two
12301 non-weak, unaliased, static _DECL nodes.
12303 It is both wasteful and incorrect to call operand_equal_p
12304 to compare the two ADDR_EXPR nodes. It is wasteful in that
12305 all we need to do is test pointer equality for the arguments
12306 to the two ADDR_EXPR nodes. It is incorrect to use
12307 operand_equal_p as that function is NOT equivalent to a
12308 C equality test. It can in fact return false for two
12309 objects which would test as equal using the C equality
12310 operator. */
12314 type);
12315 }
12317 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12318 a MINUS_EXPR of a constant, we can convert it into a comparison with
12319 a revised constant as long as no overflow occurs. */
12331 /* Similarly for a NEGATE_EXPR. */
12339 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12348 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12355 {
12359 val,
12363 }
12365 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12370 {
12372 code == NE_EXPR
12375 }
12377 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12378 for !=. Don't do this for ordered comparisons due to overflow. */
12384 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12389 /* If this is an EQ or NE comparison with zero and ARG0 is
12390 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12391 two operations, but the latter can be done in one less insn
12392 on machines that have only two-operand insns or on which a
12393 constant cannot be the first operand. */
12396 {
12401 {
12408 }
12411 {
12418 }
12419 }
12421 /* If this is an NE or EQ comparison of zero against the result of a
12422 signed MOD operation whose second operand is a power of 2, make
12423 the MOD operation unsigned since it is simpler and equivalent. */
12431 {
12441 }
12443 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12444 C1 is a valid shift constant, and C2 is a power of two, i.e.
12445 a single bit. */
12449 == INTEGER_CST
12452 {
12457 /* Check for a valid shift count. */
12460 {
12464 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12465 can be rewritten as (X & (C2 << C1)) != 0. */
12467 {
12471 }
12472 /* Otherwise, for signed (arithmetic) shifts,
12473 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12474 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12478 /* Otherwise, of unsigned (logical) shifts,
12479 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12480 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12481 else
12485 arg000);
12486 }
12487 }
12489 /* If this is an NE comparison of zero with an AND of one, remove the
12490 comparison since the AND will give the correct value. */
12497 /* If we have (A & C) == C where C is a power of 2, convert this into
12498 (A & C) != 0. Similarly for NE_EXPR. */
12504 integer_zero_node));
12506 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12507 bit, then fold the expression into A < 0 or A >= 0. */
12512 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12513 Similarly for NE_EXPR. */
12517 {
12526 }
12528 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12529 Similarly for NE_EXPR. */
12533 {
12540 }
12542 /* If this is a comparison of a field, we may be able to simplify it. */
12545 /* Handle the constant case even without -O
12546 to make sure the warnings are given. */
12548 {
12552 }
12554 /* Optimize comparisons of strlen vs zero to a compare of the
12555 first character of the string vs zero. To wit,
12556 strlen(ptr) == 0 => *ptr == 0
12557 strlen(ptr) != 0 => *ptr != 0
12558 Other cases should reduce to one of these two (or a constant)
12559 due to the return value of strlen being unsigned. */
12562 {
12570 {
12574 }
12575 }
12577 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12578 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12582 {
12589 {
12591 {
12594 }
12597 }
12598 }
12600 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12606 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12611 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12618 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12626 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12627 (X & C) == 0 when C is a single bit. */
12632 {
12638 }
12640 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12641 constant C is a power of two, i.e. a single bit. */
12648 {
12652 }
12654 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12655 when is C is a power of two, i.e. a single bit. */
12662 {
12668 }
12672 {
12675 }
12677 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12684 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12687 {
12699 arg01),
12707 arg01),
12715 arg00),
12723 arg00),
12725 }
12729 {
12736 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12737 operand_equal_p guarantees no side-effects so we don't need
12738 to use omit_one_operand on Z. */
12748 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12755 arg10);
12756 }
12758 /* Attempt to simplify equality/inequality comparisons of complex
12759 values. Only lower the comparison if the result is known or
12760 can be simplified to a single scalar comparison. */
12765 {
12770 {
12773 }
12774 else
12775 {
12778 }
12781 {
12784 }
12785 else
12786 {
12789 }
12793 {
12795 {
12800 }
12801 else
12802 {
12807 }
12808 }
12812 {
12814 {
12819 }
12820 else
12821 {
12826 }
12827 }
12828 }
12840 /* Transform comparisons of the form X +- C CMP X. */
12847 {
12854 else
12857 /* (X - c) > X becomes false. */
12861 {
12865 "occur when assuming that (X - c) > X "
12867 WARN_STRICT_OVERFLOW_ALL);
12869 }
12871 /* Likewise (X + c) < X becomes false. */
12875 {
12879 "occur when assuming that "
12881 WARN_STRICT_OVERFLOW_ALL);
12883 }
12885 /* Convert (X - c) <= X to true. */
12890 {
12894 "occur when assuming that "
12896 WARN_STRICT_OVERFLOW_ALL);
12898 }
12900 /* Convert (X + c) >= X to true. */
12905 {
12909 "occur when assuming that "
12911 WARN_STRICT_OVERFLOW_ALL);
12913 }
12916 {
12917 /* Convert X + c > X and X - c < X to true for integers. */
12921 {
12924 "not occur when assuming that "
12926 WARN_STRICT_OVERFLOW_ALL);
12928 }
12933 {
12936 "not occur when assuming that "
12938 WARN_STRICT_OVERFLOW_ALL);
12940 }
12942 /* Convert X + c <= X and X - c >= X to false for integers. */
12946 {
12949 "not occur when assuming that "
12951 WARN_STRICT_OVERFLOW_ALL);
12953 }
12958 {
12961 "not occur when assuming that "
12963 WARN_STRICT_OVERFLOW_ALL);
12965 }
12966 }
12967 }
12969 /* Comparisons with the highest or lowest possible integer of
12970 the specified precision will have known values. */
12971 {
12978 {
12979 HOST_WIDE_INT signed_max_hi;
12984 {
12991 {
12995 }
12996 else
12997 {
13001 }
13002 }
13003 else
13004 {
13013 {
13016 }
13017 else
13018 {
13021 }
13022 }
13027 {
13040 /* The GE_EXPR and LT_EXPR cases above are not normally
13041 reached because of previous transformations. */
13045 }
13047 == max_hi
13050 {
13056 arg1);
13062 arg1);
13065 }
13067 == min_hi
13070 {
13085 }
13087 == min_hi
13090 {
13095 arg1);
13100 arg1);
13103 }
13108 /* We will flip the signedness of the comparison operator
13109 associated with the mode of arg1, so the sign bit is
13110 specified by this mode. Check that arg1 is the signed
13111 max associated with this sign bit. */
13113 /* signed_type does not work on pointer types. */
13115 {
13116 /* The following case also applies to X < signed_max+1
13117 and X >= signed_max+1 because previous transformations. */
13119 {
13120 tree st;
13125 }
13126 }
13127 }
13128 }
13130 /* If we are comparing an ABS_EXPR with a constant, we can
13131 convert all the cases into explicit comparisons, but they may
13132 well not be faster than doing the ABS and one comparison.
13133 But ABS (X) <= C is a range comparison, which becomes a subtraction
13134 and a comparison, and is probably faster. */
13148 /* Convert ABS_EXPR<x> >= 0 to true. */
13155 {
13158 "when simplifying comparison of "
13160 WARN_STRICT_OVERFLOW_CONDITIONAL);
13162 }
13164 /* Convert ABS_EXPR<x> < 0 to false. */
13169 {
13172 "when simplifying comparison of "
13174 WARN_STRICT_OVERFLOW_CONDITIONAL);
13176 }
13178 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13179 and similarly for >= into !=. */
13194 return
13213 {
13217 }
13219 /* If the first operand is NaN, the result is constant. */
13223 {
13225 ? integer_zero_node
13228 }
13230 /* If the second operand is NaN, the result is constant. */
13234 {
13236 ? integer_zero_node
13239 }
13241 /* Simplify unordered comparison of something with itself. */
13247 && !flag_trapping_math
13251 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13252 {
13263 }
13268 /* When pedantic, a compound expression can be neither an lvalue
13269 nor an integer constant expression. */
13272 /* Don't let (0, 0) be null pointer constant. */
13286 /* An ASSERT_EXPR should never be passed to fold_binary. */
13292 }
13294 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13295 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13296 of GOTO_EXPR. */
13298 static tree
13300 {
13302 {
13309 /* ... fall through ... */
13313 }
13314 }
13316 /* Return whether the sub-tree ST contains a label which is accessible from
13317 outside the sub-tree. */
13319 static bool
13321 {
13322 return
13324 }
13326 /* Fold a ternary expression of code CODE and type TYPE with operands
13327 OP0, OP1, and OP2. Return the folded expression if folding is
13328 successful. Otherwise, return NULL_TREE. */
13330 tree
13332 {
13333 tree tem;
13340 /* Strip any conversions that don't change the mode. This is safe
13341 for every expression, except for a comparison expression because
13342 its signedness is derived from its operands. So, in the latter
13343 case, only strip conversions that don't change the signedness.
13345 Note that this is done as an internal manipulation within the
13346 constant folder, in order to find the simplest representation of
13347 the arguments so that their form can be studied. In any cases,
13348 the appropriate type conversions should be put back in the tree
13349 that will get out of the constant folder. */
13351 {
13354 }
13357 {
13360 }
13363 {
13367 {
13373 }
13377 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13378 so all simple results must be passed through pedantic_non_lvalue. */
13380 {
13383 /* Only optimize constant conditions when the selected branch
13384 has the same type as the COND_EXPR. This avoids optimizing
13385 away "c ? x : throw", where the throw has a void type.
13386 Avoid throwing away that operand which contains label. */
13393 }
13397 /* If we have A op B ? A : C, we may be able to convert this to a
13398 simpler expression, depending on the operation and the values
13399 of B and C. Signed zeros prevent all of these transformations,
13400 for reasons given above each one.
13402 Also try swapping the arguments and inverting the conditional. */
13407 {
13411 }
13415 op2,
13418 {
13421 {
13425 }
13426 }
13428 /* If the second operand is simpler than the third, swap them
13429 since that produces better jump optimization results. */
13432 {
13433 /* See if this can be inverted. If it can't, possibly because
13434 it was a floating-point inequality comparison, don't do
13435 anything. */
13439 }
13441 /* Convert A ? 1 : 0 to simply A. */
13444 /* If we try to convert OP0 to our type, the
13445 call to fold will try to move the conversion inside
13446 a COND, which will recurse. In that case, the COND_EXPR
13447 is probably the best choice, so leave it alone. */
13451 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13452 over COND_EXPR in cases such as floating point comparisons. */
13459 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13464 {
13465 /* sign_bit_p only checks ARG1 bits within A's precision.
13466 If <sign bit of A> has wider type than A, bits outside
13467 of A's precision in <sign bit of A> need to be checked.
13468 If they are all 0, this optimization needs to be done
13469 in unsigned A's type, if they are all 1 in signed A's type,
13470 otherwise this can't be done. */
13475 {
13477 HOST_WIDE_INT mask_hi;
13479 tree tem_type;
13487 {
13491 }
13492 else
13493 {
13497 }
13499 {
13503 }
13504 else
13510 {
13513 }
13516 {
13519 }
13520 else
13522 }
13529 arg1)));
13530 }
13532 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13533 already handled above. */
13538 {
13547 }
13549 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13550 is probably obsolete because the first operand should be a
13551 truth value (that's why we have the two cases above), but let's
13552 leave it in until we can confirm this for all front-ends. */
13563 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13569 arg1);
13571 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13575 {
13576 /* Only perform transformation if ARG0 is easily inverted. */
13581 arg1);
13582 }
13584 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13588 {
13589 /* Only perform transformation if ARG0 is easily inverted. */
13594 op2);
13595 }
13597 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13603 op2);
13608 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13609 of fold_ternary on them. */
13616 {
13625 {
13630 else
13631 {
13633 tree value;
13637 }
13642 else
13644 }
13645 }
13647 /* A bit-field-ref that referenced the full argument can be stripped. */
13658 }
13660 /* Perform constant folding and related simplification of EXPR.
13661 The related simplifications include x*1 => x, x*0 => 0, etc.,
13662 and application of the associative law.
13663 NOP_EXPR conversions may be removed freely (as long as we
13664 are careful not to change the type of the overall expression).
13665 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13666 but we can constant-fold them if they have constant operands. */
13668 #ifdef ENABLE_FOLD_CHECKING
13669 # define fold(x) fold_1 (x)
13671 static
13672 #endif
13673 tree
13675 {
13679 tree tem;
13681 /* Return right away if a constant. */
13685 /* CALL_EXPR-like objects with variable numbers of operands are
13686 treated specially. */
13688 {
13690 {
13693 }
13695 }
13698 {
13703 {
13721 }
13722 }
13725 {
13727 {
13734 {
13739 /* Find a matching index by means of a binary search. */
13741 {
13757 else
13759 }
13760 }
13763 }
13771 }
13773 #ifdef ENABLE_FOLD_CHECKING
13774 #undef fold
13780 /* When --enable-checking=fold, compute a digest of expr before
13781 and after actual fold call to see if fold did not accidentally
13782 change original expr. */
13784 tree
13786 {
13787 tree ret;
13790 htab_t ht;
13809 }
13811 void
13813 {
13816 htab_t ht;
13826 }
13828 static void
13830 {
13832 }
13834 static void
13836 {
13842 recursive_label:
13856 {
13857 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13861 }
13868 {
13869 /* Allow these fields to be modified. */
13870 tree tmp;
13878 {
13881 }
13882 }
13891 {
13894 {
13908 }
13912 {
13925 }
13942 {
13948 }
13953 {
13957 }
13968 {
13971 }
13981 }
13982 }
13984 /* Helper function for outputting the checksum of a tree T. When
13985 debugging with gdb, you can "define mynext" to be "next" followed
13986 by "call debug_fold_checksum (op0)", then just trace down till the
13987 outputs differ. */
13989 void
13991 {
14006 }
14008 #endif
14010 /* Fold a unary tree expression with code CODE of type TYPE with an
14011 operand OP0. Return a folded expression if successful. Otherwise,
14012 return a tree expression with code CODE of type TYPE with an
14013 operand OP0. */
14015 tree
14017 {
14018 tree tem;
14019 #ifdef ENABLE_FOLD_CHECKING
14022 htab_t ht;
14029 #endif
14035 #ifdef ENABLE_FOLD_CHECKING
14043 #endif
14045 }
14047 /* Fold a binary tree expression with code CODE of type TYPE with
14048 operands OP0 and OP1. Return a folded expression if successful.
14049 Otherwise, return a tree expression with code CODE of type TYPE
14050 with operands OP0 and OP1. */
14052 tree
14054 MEM_STAT_DECL)
14055 {
14056 tree tem;
14057 #ifdef ENABLE_FOLD_CHECKING
14063 htab_t ht;
14075 #endif
14081 #ifdef ENABLE_FOLD_CHECKING
14097 #endif
14099 }
14101 /* Fold a ternary tree expression with code CODE of type TYPE with
14102 operands OP0, OP1, and OP2. Return a folded expression if
14103 successful. Otherwise, return a tree expression with code CODE of
14104 type TYPE with operands OP0, OP1, and OP2. */
14106 tree
14108 MEM_STAT_DECL)
14109 {
14110 tree tem;
14111 #ifdef ENABLE_FOLD_CHECKING
14119 htab_t ht;
14136 #endif
14143 #ifdef ENABLE_FOLD_CHECKING
14167 #endif
14169 }
14171 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14172 arguments in ARGARRAY, and a null static chain.
14173 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14174 of type TYPE from the given operands as constructed by build_call_array. */
14176 tree
14178 {
14179 tree tem;
14180 #ifdef ENABLE_FOLD_CHECKING
14186 htab_t ht;
14200 #endif
14204 #ifdef ENABLE_FOLD_CHECKING
14221 #endif
14223 }
14225 /* Perform constant folding and related simplification of initializer
14226 expression EXPR. These behave identically to "fold_buildN" but ignore
14227 potential run-time traps and exceptions that fold must preserve. */
14229 #define START_FOLD_INIT \
14230 int saved_signaling_nans = flag_signaling_nans;\
14231 int saved_trapping_math = flag_trapping_math;\
14232 int saved_rounding_math = flag_rounding_math;\
14233 int saved_trapv = flag_trapv;\
14234 int saved_folding_initializer = folding_initializer;\
14235 flag_signaling_nans = 0;\
14236 flag_trapping_math = 0;\
14237 flag_rounding_math = 0;\
14238 flag_trapv = 0;\
14239 folding_initializer = 1;
14241 #define END_FOLD_INIT \
14242 flag_signaling_nans = saved_signaling_nans;\
14243 flag_trapping_math = saved_trapping_math;\
14244 flag_rounding_math = saved_rounding_math;\
14245 flag_trapv = saved_trapv;\
14246 folding_initializer = saved_folding_initializer;
14248 tree
14250 {
14251 tree result;
14252 START_FOLD_INIT;
14256 END_FOLD_INIT;
14258 }
14260 tree
14262 {
14263 tree result;
14264 START_FOLD_INIT;
14268 END_FOLD_INIT;
14270 }
14272 tree
14274 tree op2)
14275 {
14276 tree result;
14277 START_FOLD_INIT;
14281 END_FOLD_INIT;
14283 }
14285 tree
14288 {
14289 tree result;
14290 START_FOLD_INIT;
14294 END_FOLD_INIT;
14296 }
14298 #undef START_FOLD_INIT
14299 #undef END_FOLD_INIT
14301 /* Determine if first argument is a multiple of second argument. Return 0 if
14302 it is not, or we cannot easily determined it to be.
14304 An example of the sort of thing we care about (at this point; this routine
14305 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14306 fold cases do now) is discovering that
14308 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14310 is a multiple of
14312 SAVE_EXPR (J * 8)
14314 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14316 This code also handles discovering that
14318 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14320 is a multiple of 8 so we don't have to worry about dealing with a
14321 possible remainder.
14323 Note that we *look* inside a SAVE_EXPR only to determine how it was
14324 calculated; it is not safe for fold to do much of anything else with the
14325 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14326 at run time. For example, the latter example above *cannot* be implemented
14327 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14328 evaluation time of the original SAVE_EXPR is not necessarily the same at
14329 the time the new expression is evaluated. The only optimization of this
14330 sort that would be valid is changing
14332 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14334 divided by 8 to
14336 SAVE_EXPR (I) * SAVE_EXPR (J)
14338 (where the same SAVE_EXPR (J) is used in the original and the
14339 transformed version). */
14341 int
14343 {
14351 {
14353 /* Bitwise and provides a power of two multiple. If the mask is
14354 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14357 /* FALLTHRU */
14370 {
14374 /* const_binop may not detect overflow correctly,
14375 so check for it explicitly here. */
14381 size_one_node,
14385 }
14389 /* Can't handle conversions from non-integral or wider integral type. */
14395 /* .. fall through ... */
14412 }
14413 }
14415 /* Return true if CODE or TYPE is known to be non-negative. */
14417 static bool
14419 {
14422 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14423 have a signed:1 type (where the value is -1 and 0). */
14426 }
14428 /* Return true if (CODE OP0) is known to be non-negative. If the return
14429 value is based on the assumption that signed overflow is undefined,
14430 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14431 *STRICT_OVERFLOW_P. */
14433 bool
14436 {
14441 {
14443 /* We can't return 1 if flag_wrapv is set because
14444 ABS_EXPR<INT_MIN> = INT_MIN. */
14453 strict_overflow_p);
14455 CASE_CONVERT:
14456 {
14461 {
14464 strict_overflow_p);
14466 {
14470 strict_overflow_p);
14471 }
14472 }
14474 {
14477 strict_overflow_p);
14481 }
14482 }
14487 }
14489 /* We don't know sign of `t', so be conservative and return false. */
14491 }
14493 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14494 value is based on the assumption that signed overflow is undefined,
14495 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14496 *STRICT_OVERFLOW_P. */
14498 bool
14501 {
14506 {
14509 /* Pointers do not have a "sign". */
14514 {
14518 }
14520 /* Fallthru. */
14524 strict_overflow_p)
14526 strict_overflow_p));
14528 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14529 both unsigned and at least 2 bits shorter than the result. */
14533 {
14538 {
14542 }
14543 }
14548 {
14550 /* x * x without overflowing is always non-negative. */
14555 }
14557 /* Fallthru. */
14560 {
14561 /* x * x for floating point x is always non-negative. */
14565 strict_overflow_p)
14567 strict_overflow_p));
14568 }
14570 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14571 both unsigned and their total bits is shorter than the result. */
14575 {
14594 {
14604 }
14605 }
14611 strict_overflow_p)
14613 strict_overflow_p));
14624 strict_overflow_p)
14626 strict_overflow_p));
14633 strict_overflow_p);
14636 }
14638 /* We don't know sign of `t', so be conservative and return false. */
14640 }
14642 /* Return true if T is known to be non-negative. If the return
14643 value is based on the assumption that signed overflow is undefined,
14644 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14645 *STRICT_OVERFLOW_P. */
14647 bool
14649 {
14654 {
14666 strict_overflow_p)
14668 strict_overflow_p));
14672 }
14673 /* We don't know sign of `t', so be conservative and return false. */
14675 }
14677 /* Return true if T is known to be non-negative. If the return
14678 value is based on the assumption that signed overflow is undefined,
14679 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14680 *STRICT_OVERFLOW_P. */
14682 bool
14685 {
14688 {
14706 /* Always true. */
14710 /* sqrt(-0.0) is -0.0. */
14714 strict_overflow_p);
14747 /* True if the 1st argument is nonnegative. */
14749 strict_overflow_p);
14752 /* True if the 1st OR 2nd arguments are nonnegative. */
14754 strict_overflow_p)
14756 strict_overflow_p)));
14759 /* True if the 1st AND 2nd arguments are nonnegative. */
14761 strict_overflow_p)
14763 strict_overflow_p)));
14766 /* True if the 2nd argument is nonnegative. */
14768 strict_overflow_p);
14771 /* True if the 1st argument is nonnegative or the second
14772 argument is an even integer. */
14777 strict_overflow_p);
14780 /* True if the 1st argument is nonnegative or the second
14781 argument is an even integer valued real. */
14783 {
14784 REAL_VALUE_TYPE c;
14785 HOST_WIDE_INT n;
14790 {
14791 REAL_VALUE_TYPE cint;
14796 }
14797 }
14799 strict_overflow_p);
14803 }
14805 type);
14806 }
14808 /* Return true if T is known to be non-negative. If the return
14809 value is based on the assumption that signed overflow is undefined,
14810 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14811 *STRICT_OVERFLOW_P. */
14813 bool
14815 {
14821 {
14823 {
14827 /* If the initializer is non-void, then it's a normal expression
14828 that will be assigned to the slot. */
14832 /* Otherwise, the initializer sets the slot in some way. One common
14833 way is an assignment statement at the end of the initializer. */
14835 {
14843 else
14845 }
14849 strict_overflow_p);
14852 }
14855 {
14861 arg0,
14862 arg1,
14863 strict_overflow_p);
14864 }
14868 strict_overflow_p);
14871 strict_overflow_p);
14874 strict_overflow_p);
14879 }
14881 /* We don't know sign of `t', so be conservative and return false. */
14883 }
14885 /* Return true if T is known to be non-negative. If the return
14886 value is based on the assumption that signed overflow is undefined,
14887 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14888 *STRICT_OVERFLOW_P. */
14890 bool
14892 {
14899 {
14906 strict_overflow_p);
14912 strict_overflow_p);
14921 }
14924 {
14932 strict_overflow_p);
14937 strict_overflow_p);
14952 }
14953 }
14955 /* Return true if `t' is known to be non-negative. Handle warnings
14956 about undefined signed overflow. */
14958 bool
14960 {
14967 "determining that expression is always "
14969 WARN_STRICT_OVERFLOW_MISC);
14971 }
14974 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14975 For floating point we further ensure that T is not denormal.
14976 Similar logic is present in nonzero_address in rtlanal.h.
14978 If the return value is based on the assumption that signed overflow
14979 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14980 change *STRICT_OVERFLOW_P. */
14982 bool
14985 {
14987 {
14990 strict_overflow_p);
14993 {
14999 strict_overflow_p));
15000 }
15005 strict_overflow_p);
15009 }
15012 }
15014 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15015 For floating point we further ensure that T is not denormal.
15016 Similar logic is present in nonzero_address in rtlanal.h.
15018 If the return value is based on the assumption that signed overflow
15019 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15020 change *STRICT_OVERFLOW_P. */
15022 bool
15024 tree type ATTRIBUTE_UNUSED,
15025 tree op0,
15027 {
15030 {
15034 {
15035 /* With the presence of negative values it is hard
15036 to say something. */
15043 /* One of operands must be positive and the other non-negative. */
15044 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15045 overflows, on a twos-complement machine the sum of two
15046 nonnegative numbers can never be zero. */
15048 strict_overflow_p)
15050 strict_overflow_p));
15051 }
15056 {
15058 strict_overflow_p)
15060 strict_overflow_p))
15061 {
15064 }
15065 }
15074 {
15077 }
15084 {
15088 /* When both operands are nonzero, then MAX must be too. */
15090 strict_overflow_p))
15093 /* MAX where operand 0 is positive is positive. */
15095 strict_overflow_p);
15096 }
15097 /* MAX where operand 1 is positive is positive. */
15102 {
15106 }
15111 strict_overflow_p)
15113 strict_overflow_p));
15117 }
15120 }
15122 /* Return true when T is an address and is known to be nonzero.
15123 For floating point we further ensure that T is not denormal.
15124 Similar logic is present in nonzero_address in rtlanal.h.
15126 If the return value is based on the assumption that signed overflow
15127 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15128 change *STRICT_OVERFLOW_P. */
15130 bool
15132 {
15135 {
15140 {
15146 /* Weak declarations may link to NULL. Other things may also be NULL
15147 so protect with -fdelete-null-pointer-checks; but not variables
15148 allocated on the stack. */
15150 && (flag_delete_null_pointer_checks
15154 /* Constants are never weak. */
15159 }
15167 {
15171 }
15176 }
15178 }
15180 /* Return true when T is an address and is known to be nonzero.
15181 For floating point we further ensure that T is not denormal.
15182 Similar logic is present in nonzero_address in rtlanal.h.
15184 If the return value is based on the assumption that signed overflow
15185 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15186 change *STRICT_OVERFLOW_P. */
15188 bool
15190 {
15194 /* Doing something useful for floating point would need more work. */
15200 {
15203 strict_overflow_p);
15209 strict_overflow_p);
15217 }
15220 {
15223 strict_overflow_p);
15231 strict_overflow_p);
15248 strict_overflow_p);
15252 strict_overflow_p);
15259 }
15261 }
15263 /* Return true when T is an address and is known to be nonzero.
15264 Handle warnings about undefined signed overflow. */
15266 bool
15268 {
15275 "determining that expression is always "
15277 WARN_STRICT_OVERFLOW_MISC);
15279 }
15281 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15282 attempt to fold the expression to a constant without modifying TYPE,
15283 OP0 or OP1.
15285 If the expression could be simplified to a constant, then return
15286 the constant. If the expression would not be simplified to a
15287 constant, then return NULL_TREE. */
15289 tree
15291 {
15294 }
15296 /* Given the components of a unary expression CODE, TYPE and OP0,
15297 attempt to fold the expression to a constant without modifying
15298 TYPE or OP0.
15300 If the expression could be simplified to a constant, then return
15301 the constant. If the expression would not be simplified to a
15302 constant, then return NULL_TREE. */
15304 tree
15306 {
15309 }
15311 /* If EXP represents referencing an element in a constant string
15312 (either via pointer arithmetic or array indexing), return the
15313 tree representing the value accessed, otherwise return NULL. */
15315 tree
15317 {
15321 {
15323 tree index;
15324 tree string;
15328 else
15329 {
15333 /* Optimize the special-case of a zero lower bound.
15335 We convert the low_bound to sizetype to avoid some problems
15336 with constant folding. (E.g. suppose the lower bound is 1,
15337 and its mode is QI. Without the conversion,l (ARRAY
15338 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15339 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15344 }
15357 }
15359 }
15361 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15362 an integer constant, real, or fixed-point constant.
15364 TYPE is the type of the result. */
15366 static tree
15368 {
15372 {
15374 {
15376 HOST_WIDE_INT high;
15384 }
15391 {
15392 FIXED_VALUE_TYPE f;
15397 /* Propagate overflow flags. */
15401 }
15405 }
15408 }
15410 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15411 an integer constant or real constant.
15413 TYPE is the type of the result. */
15415 tree
15417 {
15421 {
15423 /* If the value is unsigned, then the absolute value is
15424 the same as the ordinary value. */
15427 /* Similarly, if the value is non-negative. */
15430 /* If the value is negative, then the absolute value is
15431 its negation. */
15432 else
15433 {
15435 HOST_WIDE_INT high;
15441 }
15447 else
15453 }
15456 }
15458 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15459 constant. TYPE is the type of the result. */
15461 static tree
15463 {
15473 }
15475 /* Given CODE, a relational operator, the target type, TYPE and two
15476 constant operands OP0 and OP1, return the result of the
15477 relational operation. If the result is not a compile time
15478 constant, then return NULL_TREE. */
15480 static tree
15482 {
15485 /* From here on, the only cases we handle are when the result is
15486 known to be a constant. */
15489 {
15493 /* Handle the cases where either operand is a NaN. */
15495 {
15497 {
15525 }
15528 }
15531 }
15534 {
15538 }
15540 /* Handle equality/inequality of complex constants. */
15542 {
15553 else
15555 }
15557 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15559 To compute GT, swap the arguments and do LT.
15560 To compute GE, do LT and invert the result.
15561 To compute LE, swap the arguments, do LT and invert the result.
15562 To compute NE, do EQ and invert the result.
15564 Therefore, the code below must handle only EQ and LT. */
15567 {
15572 }
15574 /* Note that it is safe to invert for real values here because we
15575 have already handled the one case that it matters. */
15579 {
15582 }
15584 /* Compute a result for LT or EQ if args permit;
15585 Otherwise return T. */
15587 {
15592 else
15594 }
15595 else
15601 }
15603 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15604 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15605 itself. */
15607 tree
15609 {
15610 /* If the expression does not have side effects then we don't have to wrap
15611 it with a cleanup point expression. */
15615 /* If the expression is a return, check to see if the expression inside the
15616 return has no side effects or the right hand side of the modify expression
15617 inside the return. If either don't have side effects set we don't need to
15618 wrap the expression in a cleanup point expression. Note we don't check the
15619 left hand side of the modify because it should always be a return decl. */
15621 {
15628 }
15631 }
15633 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15634 of an indirection through OP0, or NULL_TREE if no simplification is
15635 possible. */
15637 tree
15639 {
15641 tree subtype;
15649 {
15652 /* *&CONST_DECL -> to the value of the const decl. */
15655 /* *&p => p; make sure to handle *&"str"[cst] here. */
15657 {
15661 else
15663 }
15664 /* *(foo *)&fooarray => fooarray[0] */
15667 {
15673 }
15674 /* *(foo *)&complexfoo => __real__ complexfoo */
15678 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15681 {
15685 }
15686 }
15688 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15691 {
15694 tree op00type;
15701 {
15712 }
15713 }
15716 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15719 {
15722 tree op00type;
15729 {
15733 }
15734 }
15736 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15739 {
15740 tree type_domain;
15747 }
15750 }
15752 /* Builds an expression for an indirection through T, simplifying some
15753 cases. */
15755 tree
15757 {
15763 else
15765 }
15767 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15769 tree
15771 {
15776 else
15778 }
15780 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15781 whose result is ignored. The type of the returned tree need not be
15782 the same as the original expression. */
15784 tree
15786 {
15792 {
15803 else
15809 {
15825 }
15830 }
15831 }
15833 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15834 This can only be applied to objects of a sizetype. */
15836 tree
15838 {
15845 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15846 have to do anything. Only do this when we are not given a const,
15847 because in that case, this check is more expensive than just
15848 doing it. */
15850 {
15855 }
15857 /* If divisor is a power of two, simplify this to bit manipulation. */
15859 {
15861 {
15874 {
15875 high++;
15878 }
15882 }
15883 else
15884 {
15885 tree t;
15891 }
15892 }
15893 else
15894 {
15899 }
15902 }
15904 /* Likewise, but round down. */
15906 tree
15908 {
15915 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15916 have to do anything. Only do this when we are not given a const,
15917 because in that case, this check is more expensive than just
15918 doing it. */
15920 {
15925 }
15927 /* If divisor is a power of two, simplify this to bit manipulation. */
15929 {
15930 tree t;
15934 }
15935 else
15936 {
15941 }
15944 }
15946 /* Returns the pointer to the base of the object addressed by EXP and
15947 extracts the information about the offset of the access, storing it
15948 to PBITPOS and POFFSET. */
15950 static tree
15953 {
15954 tree core;
15957 HOST_WIDE_INT bitsize;
15960 {
15965 }
15966 else
15967 {
15971 }
15974 }
15976 /* Returns true if addresses of E1 and E2 differ by a constant, false
15977 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15979 bool
15981 {
15995 {
16005 }
16007 {
16008 /* If only one of the offsets is non-constant, the difference cannot
16009 be a constant. */
16011 }
16012 else
16017 }
16019 /* Simplify the floating point expression EXP when the sign of the
16020 result is not significant. Return NULL_TREE if no simplification
16021 is possible. */
16023 tree
16025 {
16029 {
16064 {
16067 {
16069 /* Strip copysign function call, return the 1st argument. */
16075 /* Strip sign ops from the argument of "odd" math functions. */
16077 {
16081 }
16083 }
16084 }
16089 }
16091 }