| blob | daad1ba3d41f5ba6840bc5f23c9598c8ff709d35 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, 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 COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
21 02110-1301, USA. */
23 /*@@ This file should be rewritten to use an arbitrary precision
24 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
25 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
26 @@ The routines that translate from the ap rep should
27 @@ warn if precision et. al. is lost.
28 @@ This would also make life easier when this technology is used
29 @@ for cross-compilers. */
31 /* The entry points in this file are fold, size_int_wide, size_binop
32 and force_fit_type_double.
34 fold takes a tree as argument and returns a simplified tree.
36 size_binop takes a tree code for an arithmetic operation
37 and two operands that are trees, and produces a tree for the
38 result, assuming the type comes from `sizetype'.
40 size_int takes an integer value, and creates a tree constant
41 with type from `sizetype'.
43 force_fit_type_double takes a constant, an overflowable flag and a
44 prior overflow indicator. It forces the value to fit the type and
45 sets TREE_OVERFLOW.
47 Note: Since the folders get called on non-gimple code as well as
48 gimple code, we need to handle GIMPLE tuples as well as their
49 corresponding tree equivalents. */
68 /* Non-zero if we are folding constants inside an initializer; zero
69 otherwise. */
72 /* The following constants represent a bit based encoding of GCC's
73 comparison operators. This encoding simplifies transformations
74 on relational comparison operators, such as AND and OR. */
92 };
126 tree);
150 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
151 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
152 and SUM1. Then this yields nonzero if overflow occurred during the
153 addition.
155 Overflow occurs if A and B have the same sign, but A and SUM differ in
156 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
157 sign. */
158 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
159 \f
160 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
161 We do that by representing the two-word integer in 4 words, with only
162 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
163 number. The value of the word is LOWPART + HIGHPART * BASE. */
165 #define LOWPART(x) \
166 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
167 #define HIGHPART(x) \
168 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
169 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
171 /* Unpack a two-word integer into 4 words.
172 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
173 WORDS points to the array of HOST_WIDE_INTs. */
175 static void
177 {
182 }
184 /* Pack an array of 4 words into a two-word integer.
185 WORDS points to the array of words.
186 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
188 static void
191 {
194 }
195 \f
196 /* Force the double-word integer L1, H1 to be within the range of the
197 integer type TYPE. Stores the properly truncated and sign-extended
198 double-word integer in *LV, *HV. Returns true if the operation
199 overflows, that is, argument and result are different. */
201 int
204 {
213 else
216 /* Size types *are* sign extended. */
221 /* First clear all bits that are beyond the type's precision. */
223 ;
226 else
227 {
231 }
233 /* Then do sign extension if necessary. */
239 {
240 /* Sign extend top half? */
244 }
246 {
249 }
250 else
251 {
252 /* Sign extend bottom half? */
254 {
257 }
258 }
263 /* If the value didn't fit, signal overflow. */
265 }
267 /* We force the double-int HIGH:LOW to the range of the type TYPE by
268 sign or zero extending it.
269 OVERFLOWABLE indicates if we are interested
270 in overflow of the value, when >0 we are only interested in signed
271 overflow, for <0 we are interested in any overflow. OVERFLOWED
272 indicates whether overflow has already occurred. CONST_OVERFLOWED
273 indicates whether constant overflow has already occurred. We force
274 T's value to be within range of T's type (by setting to 0 or 1 all
275 the bits outside the type's range). We set TREE_OVERFLOWED if,
276 OVERFLOWED is nonzero,
277 or OVERFLOWABLE is >0 and signed overflow occurs
278 or OVERFLOWABLE is <0 and any overflow occurs
279 We return a new tree node for the extended double-int. The node
280 is shared if no overflow flags are set. */
282 tree
286 {
290 /* Size types *are* sign extended. */
297 /* If we need to set overflow flags, return a new unshared node. */
299 {
303 {
310 }
311 }
313 /* Else build a shared node. */
315 }
316 \f
317 /* Add two doubleword integers with doubleword result.
318 Return nonzero if the operation overflows according to UNSIGNED_P.
319 Each argument is given as two `HOST_WIDE_INT' pieces.
320 One argument is L1 and H1; the other, L2 and H2.
321 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
323 int
328 {
330 HOST_WIDE_INT h;
340 else
342 }
344 /* Negate a doubleword integer with doubleword result.
345 Return nonzero if the operation overflows, assuming it's signed.
346 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
347 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
349 int
352 {
354 {
358 }
359 else
360 {
364 }
365 }
366 \f
367 /* Multiply two doubleword integers with doubleword result.
368 Return nonzero if the operation overflows according to UNSIGNED_P.
369 Each argument is given as two `HOST_WIDE_INT' pieces.
370 One argument is L1 and H1; the other, L2 and H2.
371 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
373 int
378 {
393 {
396 {
398 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
400 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
404 }
406 }
411 /* Unsigned overflow is immediate. */
415 /* Check for signed overflow by calculating the signed representation of the
416 top half of the result; it should agree with the low half's sign bit. */
418 {
421 }
423 {
426 }
428 }
429 \f
430 /* Shift the doubleword integer in L1, H1 left by COUNT places
431 keeping only PREC bits of result.
432 Shift right if COUNT is negative.
433 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
434 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
436 void
440 {
444 {
447 }
453 {
454 /* Shifting by the host word size is undefined according to the
455 ANSI standard, so we must handle this as a special case. */
458 }
460 {
463 }
464 else
465 {
469 }
471 /* Sign extend all bits that are beyond the precision. */
479 ;
481 {
484 }
485 else
486 {
490 }
491 }
493 /* Shift the doubleword integer in L1, H1 right by COUNT places
494 keeping only PREC bits of result. COUNT must be positive.
495 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
496 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
498 void
503 {
506 signmask = (arith
514 {
515 /* Shifting by the host word size is undefined according to the
516 ANSI standard, so we must handle this as a special case. */
519 }
521 {
524 }
525 else
526 {
530 }
532 /* Zero / sign extend all bits that are beyond the precision. */
535 {
538 }
540 ;
542 {
545 }
546 else
547 {
551 }
552 }
553 \f
554 /* Rotate the doubleword integer in L1, H1 left by COUNT places
555 keeping only PREC bits of result.
556 Rotate right if COUNT is negative.
557 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
559 void
563 {
575 }
577 /* Rotate the doubleword integer in L1, H1 left by COUNT places
578 keeping only PREC bits of result. COUNT must be positive.
579 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
581 void
585 {
597 }
598 \f
599 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
600 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
601 CODE is a tree code for a kind of division, one of
602 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
603 or EXACT_DIV_EXPR
604 It controls how the quotient is rounded to an integer.
605 Return nonzero if the operation overflows.
606 UNS nonzero says do unsigned division. */
608 int
611 HOST_WIDE_INT hnum_orig,
613 HOST_WIDE_INT hden_orig,
617 {
633 /* Calculate quotient sign and convert operands to unsigned. */
635 {
637 {
639 /* (minimum integer) / (-1) is the only overflow case. */
643 }
645 {
648 }
649 }
654 /* This unsigned division rounds toward zero. */
657 }
661 /* hden != 0 already checked. */
666 }
676 /* Special code for when the divisor < BASE. */
678 {
679 /* hnum != 0 already checked. */
681 {
685 }
686 }
687 else
688 {
689 /* Full double precision division,
690 with thanks to Don Knuth's "Seminumerical Algorithms". */
694 /* Find the highest nonzero divisor digit. */
697 {
700 }
702 /* Insure that the first digit of the divisor is at least BASE/2.
703 This is required by the quotient digit estimation algorithm. */
710 {
714 }
719 {
724 }
725 }
729 /* Main loop */
731 {
732 /* Guess the next quotient digit, quo_est, by dividing the first
733 two remaining dividend digits by the high order quotient digit.
734 quo_est is never low and is at most 2 high. */
741 else
744 /* Refine quo_est so it's usually correct, and at most one high. */
749 quo_est--;
751 /* Try QUO_EST as the quotient digit, by multiplying the
752 divisor by QUO_EST and subtracting from the remaining dividend.
753 Keep in mind that QUO_EST is the I - 1st digit. */
757 {
763 }
765 /* If quo_est was high by one, then num[i] went negative and
766 we need to correct things. */
768 {
769 quo_est--;
772 {
776 }
779 }
781 /* Store the quotient digit. */
783 }
784 }
788 finish_up:
789 /* If result is negative, make it so. */
793 /* Compute trial remainder: rem = num - (quo * den) */
799 {
808 {
809 /* quo = quo - 1; */
812 }
813 else
820 {
823 }
824 else
830 {
836 /* Get absolute values. */
842 /* If (2 * abs (lrem) >= abs (lden)) */
851 {
853 /* quo = quo - 1; */
856 else
857 /* quo = quo + 1; */
860 }
861 else
863 }
868 }
870 /* Compute true remainder: rem = num - (quo * den) */
875 }
877 /* If ARG2 divides ARG1 with zero remainder, carries out the division
878 of type CODE and returns the quotient.
879 Otherwise returns NULL_TREE. */
881 static tree
883 {
902 }
903 \f
904 /* This is non-zero if we should defer warnings about undefined
905 overflow. This facility exists because these warnings are a
906 special case. The code to estimate loop iterations does not want
907 to issue any warnings, since it works with expressions which do not
908 occur in user code. Various bits of cleanup code call fold(), but
909 only use the result if it has certain characteristics (e.g., is a
910 constant); that code only wants to issue a warning if the result is
911 used. */
915 /* If a warning about undefined overflow is deferred, this is the
916 warning. Note that this may cause us to turn two warnings into
917 one, but that is fine since it is sufficient to only give one
918 warning per expression. */
922 /* If a warning about undefined overflow is deferred, this is the
923 level at which the warning should be emitted. */
927 /* Start deferring overflow warnings. We could use a stack here to
928 permit nested calls, but at present it is not necessary. */
930 void
932 {
934 }
936 /* Stop deferring overflow warnings. If there is a pending warning,
937 and ISSUE is true, then issue the warning if appropriate. STMT is
938 the statement with which the warning should be associated (used for
939 location information); STMT may be NULL. CODE is the level of the
940 warning--a warn_strict_overflow_code value. This function will use
941 the smaller of CODE and the deferred code when deciding whether to
942 issue the warning. CODE may be zero to mean to always use the
943 deferred code. */
945 void
947 {
949 location_t locus;
954 {
960 }
968 /* Use the smallest code level when deciding to issue the
969 warning. */
978 else
981 }
983 /* Stop deferring overflow warnings, ignoring any deferred
984 warnings. */
986 void
988 {
990 }
992 /* Whether we are deferring overflow warnings. */
994 bool
996 {
998 }
1000 /* This is called when we fold something based on the fact that signed
1001 overflow is undefined. */
1003 static void
1005 {
1008 {
1011 {
1014 }
1015 }
1018 }
1019 \f
1020 /* Return true if the built-in mathematical function specified by CODE
1021 is odd, i.e. -f(x) == f(-x). */
1023 static bool
1025 {
1027 {
1061 }
1063 }
1065 /* Check whether we may negate an integer constant T without causing
1066 overflow. */
1068 bool
1070 {
1073 tree type;
1083 {
1088 }
1089 else
1094 }
1096 /* Determine whether an expression T can be cheaply negated using
1097 the function negate_expr without introducing undefined overflow. */
1099 static bool
1101 {
1102 tree type;
1111 {
1116 /* Check that -CST will not overflow type. */
1141 /* -(A + B) -> (-B) - A. */
1146 /* -(A + B) -> (-A) - B. */
1150 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1160 /* Fall through. */
1173 /* In general we can't negate A / B, because if A is INT_MIN and
1174 B is 1, we may turn this into INT_MIN / -1 which is undefined
1175 and actually traps on some architectures. But if overflow is
1176 undefined, we can negate, because - (INT_MIN / 1) is an
1177 overflow. */
1185 /* Negate -((double)float) as (double)(-float). */
1187 {
1191 }
1195 /* Negate -f(x) as f(-x). */
1201 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1203 {
1209 }
1214 }
1216 }
1218 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1219 simplification is possible.
1220 If negate_expr_p would return true for T, NULL_TREE will never be
1221 returned. */
1223 static tree
1225 {
1227 tree tem;
1230 {
1231 /* Convert - (~A) to A + 1. */
1247 /* Two's complement FP formats, such as c4x, may overflow. */
1253 {
1262 }
1284 {
1285 /* -(A + B) -> (-B) - A. */
1289 {
1293 }
1295 /* -(A + B) -> (-A) - B. */
1297 {
1301 }
1302 }
1306 /* - (A - B) -> B - A */
1318 /* Fall through. */
1322 {
1331 }
1339 /* In general we can't negate A / B, because if A is INT_MIN and
1340 B is 1, we may turn this into INT_MIN / -1 which is undefined
1341 and actually traps on some architectures. But if overflow is
1342 undefined, we can negate, because - (INT_MIN / 1) is an
1343 overflow. */
1345 {
1350 {
1357 }
1360 {
1367 }
1368 }
1372 /* Convert -((double)float) into (double)(-float). */
1374 {
1378 }
1382 /* Negate -f(x) as f(-x). */
1385 {
1391 }
1395 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1397 {
1402 {
1409 }
1410 }
1415 }
1418 }
1420 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1421 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1422 return NULL_TREE. */
1424 static tree
1426 {
1439 }
1440 \f
1441 /* Split a tree IN into a constant, literal and variable parts that could be
1442 combined with CODE to make IN. "constant" means an expression with
1443 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1444 commutative arithmetic operation. Store the constant part into *CONP,
1445 the literal in *LITP and return the variable part. If a part isn't
1446 present, set it to null. If the tree does not decompose in this way,
1447 return the entire tree as the variable part and the other parts as null.
1449 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1450 case, we negate an operand that was subtracted. Except if it is a
1451 literal for which we use *MINUS_LITP instead.
1453 If NEGATE_P is true, we are negating all of IN, again except a literal
1454 for which we use *MINUS_LITP instead.
1456 If IN is itself a literal or constant, return it as appropriate.
1458 Note that we do not guarantee that any of the three values will be the
1459 same type as IN, but they will have the same signedness and mode. */
1461 static tree
1464 {
1471 /* Strip any conversions that don't change the machine mode or signedness. */
1478 /* We can associate addition and subtraction together (even
1479 though the C standard doesn't say so) for integers because
1480 the value is not affected. For reals, the value might be
1481 affected, so we can't. */
1484 {
1490 /* First see if either of the operands is a literal, then a constant. */
1501 /* If we haven't dealt with either operand, this is not a case we can
1502 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1507 else
1510 /* Now do any needed negations. */
1517 }
1520 else
1524 {
1531 }
1534 }
1536 /* Re-associate trees split by the above function. T1 and T2 are either
1537 expressions to associate or null. Return the new expression, if any. If
1538 we build an operation, do it in TYPE and with CODE. */
1540 static tree
1542 {
1548 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1549 try to fold this since we will have infinite recursion. But do
1550 deal with any NEGATE_EXPRs. */
1553 {
1555 {
1564 }
1566 {
1569 }
1573 }
1577 }
1578 \f
1579 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1580 for use in int_const_binop, size_binop and size_diffop. */
1582 static bool
1584 {
1591 {
1600 }
1605 }
1608 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1609 to produce a new constant. Return NULL_TREE if we don't know how
1610 to evaluate CODE at compile-time.
1612 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1614 tree
1616 {
1620 HOST_WIDE_INT hi;
1622 HOST_WIDE_INT garbageh;
1623 tree t;
1626 int is_sizetype
1636 {
1652 /* It's unclear from the C standard whether shifts can overflow.
1653 The following code ignores overflow; perhaps a C standard
1654 interpretation ruling is needed. */
1683 /* This is a shortcut for a common special case. */
1688 {
1694 }
1696 /* ... fall through ... */
1702 {
1705 }
1708 {
1711 }
1718 /* This is a shortcut for a common special case. */
1723 {
1728 }
1730 /* ... fall through ... */
1748 else
1754 else
1760 }
1763 {
1766 /* Propagate overflow flags ourselves. */
1769 {
1772 }
1773 }
1774 else
1780 }
1782 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1783 constant. We assume ARG1 and ARG2 have the same data type, or at least
1784 are the same kind of constant and the same machine mode. Return zero if
1785 combining the constants is not allowed in the current operating mode.
1787 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1789 static tree
1791 {
1792 /* Sanity check for the recursive cases. */
1803 {
1805 REAL_VALUE_TYPE d1;
1806 REAL_VALUE_TYPE d2;
1807 REAL_VALUE_TYPE value;
1808 REAL_VALUE_TYPE result;
1812 /* The following codes are handled by real_arithmetic. */
1814 {
1825 }
1833 /* Don't perform operation if we honor signaling NaNs and
1834 either operand is a NaN. */
1839 /* Don't perform operation if it would raise a division
1840 by zero exception. */
1846 /* If either operand is a NaN, just return it. Otherwise, set up
1847 for floating-point trap; we return an overflow. */
1856 /* Don't constant fold this floating point operation if
1857 the result has overflowed and flag_trapping_math. */
1865 /* Don't constant fold this floating point operation if the
1866 result may dependent upon the run-time rounding mode and
1867 flag_rounding_math is set, or if GCC's software emulation
1868 is unable to accurately represent the result. */
1879 }
1882 {
1891 {
1902 notrunc);
1906 notrunc);
1910 {
1911 tree magsquared
1915 notrunc);
1916 tree t1
1920 notrunc);
1921 tree t2
1925 notrunc);
1932 }
1937 }
1941 }
1944 }
1946 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1947 indicates which particular sizetype to create. */
1949 tree
1951 {
1953 }
1954 \f
1955 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1956 is a tree code. The type of the result is taken from the operands.
1957 Both must be equivalent integer types, ala int_binop_types_match_p.
1958 If the operands are constant, so is the result. */
1960 tree
1962 {
1971 /* Handle the special case of two integer constants faster. */
1973 {
1974 /* And some specific cases even faster than that. */
1976 {
1981 }
1983 {
1986 }
1988 {
1991 }
1993 /* Handle general case of two integer constants. */
1995 }
1998 }
2000 /* Given two values, either both of sizetype or both of bitsizetype,
2001 compute the difference between the two values. Return the value
2002 in signed type corresponding to the type of the operands. */
2004 tree
2006 {
2008 tree ctype;
2013 /* If the type is already signed, just do the simple thing. */
2021 else
2024 /* If either operand is not a constant, do the conversions to the signed
2025 type and subtract. The hardware will do the right thing with any
2026 overflow in the subtraction. */
2031 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2032 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2033 overflow) and negate (which can't either). Special-case a result
2034 of zero while we're here. */
2039 else
2043 }
2044 \f
2045 /* A subroutine of fold_convert_const handling conversions of an
2046 INTEGER_CST to another integer type. */
2048 static tree
2050 {
2051 tree t;
2053 /* Given an integer constant, make new constant with new type,
2054 appropriately sign-extended or truncated. */
2057 /* Don't set the overflow when
2058 converting a pointer */
2066 }
2068 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2069 to an integer type. */
2071 static tree
2073 {
2075 tree t;
2077 /* The following code implements the floating point to integer
2078 conversion rules required by the Java Language Specification,
2079 that IEEE NaNs are mapped to zero and values that overflow
2080 the target precision saturate, i.e. values greater than
2081 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2082 are mapped to INT_MIN. These semantics are allowed by the
2083 C and C++ standards that simply state that the behavior of
2084 FP-to-integer conversion is unspecified upon overflow. */
2087 REAL_VALUE_TYPE r;
2091 {
2098 }
2100 /* If R is NaN, return zero and show we have an overflow. */
2102 {
2106 }
2108 /* See if R is less than the lower bound or greater than the
2109 upper bound. */
2112 {
2116 {
2120 }
2121 }
2124 {
2127 {
2130 {
2134 }
2135 }
2136 }
2144 }
2146 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2147 to another floating point type. */
2149 static tree
2151 {
2152 REAL_VALUE_TYPE value;
2153 tree t;
2160 }
2162 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2163 type TYPE. If no simplification can be done return NULL_TREE. */
2165 static tree
2167 {
2172 {
2177 }
2179 {
2184 }
2186 }
2188 /* Construct a vector of zero elements of vector type TYPE. */
2190 static tree
2192 {
2203 }
2205 /* Convert expression ARG to type TYPE. Used by the middle-end for
2206 simple conversions in preference to calling the front-end's convert. */
2208 tree
2210 {
2212 tree tem;
2228 {
2233 {
2237 }
2242 {
2245 }
2252 {
2256 }
2258 {
2262 }
2265 {
2280 }
2284 {
2293 {
2297 {
2301 }
2309 }
2313 }
2331 }
2332 }
2333 \f
2334 /* Return false if expr can be assumed not to be an lvalue, true
2335 otherwise. */
2337 static bool
2339 {
2340 /* We only need to wrap lvalue tree codes. */
2342 {
2377 /* Assume the worst for front-end tree codes. */
2381 }
2384 }
2386 /* Return an expr equal to X but certainly not valid as an lvalue. */
2388 tree
2390 {
2391 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2392 us. */
2399 }
2401 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2402 Zero means allow extended lvalues. */
2406 /* When pedantic, return an expr equal to X but certainly not valid as a
2407 pedantic lvalue. Otherwise, return X. */
2409 static tree
2411 {
2414 else
2416 }
2417 \f
2418 /* Given a tree comparison code, return the code that is the logical inverse
2419 of the given code. It is not safe to do this for floating-point
2420 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2421 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2423 enum tree_code
2425 {
2430 {
2461 }
2462 }
2464 /* Similar, but return the comparison that results if the operands are
2465 swapped. This is safe for floating-point. */
2467 enum tree_code
2469 {
2471 {
2497 }
2498 }
2501 /* Convert a comparison tree code from an enum tree_code representation
2502 into a compcode bit-based encoding. This function is the inverse of
2503 compcode_to_comparison. */
2505 static enum comparison_code
2507 {
2509 {
2540 }
2541 }
2543 /* Convert a compcode bit-based encoding of a comparison operator back
2544 to GCC's enum tree_code representation. This function is the
2545 inverse of comparison_to_compcode. */
2547 static enum tree_code
2549 {
2551 {
2582 }
2583 }
2585 /* Return a tree for the comparison which is the combination of
2586 doing the AND or OR (depending on CODE) of the two operations LCODE
2587 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2588 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2589 if this makes the transformation invalid. */
2591 tree
2595 {
2602 {
2613 }
2616 {
2617 /* Eliminate unordered comparisons, as well as LTGT and ORD
2618 which are not used unless the mode has NaNs. */
2624 }
2626 {
2627 /* Check that the original operation and the optimized ones will trap
2628 under the same condition. */
2639 /* In a short-circuited boolean expression the LHS might be
2640 such that the RHS, if evaluated, will never trap. For
2641 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2642 if neither x nor y is NaN. (This is a mixed blessing: for
2643 example, the expression above will never trap, hence
2644 optimizing it to x < y would be invalid). */
2649 /* If the comparison was short-circuited, and only the RHS
2650 trapped, we may now generate a spurious trap. */
2655 /* If we changed the conditions that cause a trap, we lose. */
2658 }
2664 else
2667 }
2669 /* Return nonzero if CODE is a tree code that represents a truth value. */
2671 static int
2673 {
2678 }
2679 \f
2680 /* Return nonzero if two operands (typically of the same tree node)
2681 are necessarily equal. If either argument has side-effects this
2682 function returns zero. FLAGS modifies behavior as follows:
2684 If OEP_ONLY_CONST is set, only return nonzero for constants.
2685 This function tests whether the operands are indistinguishable;
2686 it does not test whether they are equal using C's == operation.
2687 The distinction is important for IEEE floating point, because
2688 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2689 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2691 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2692 even though it may hold multiple values during a function.
2693 This is because a GCC tree node guarantees that nothing else is
2694 executed between the evaluation of its "operands" (which may often
2695 be evaluated in arbitrary order). Hence if the operands themselves
2696 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2697 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2698 unset means assuming isochronic (or instantaneous) tree equivalence.
2699 Unless comparing arbitrary expression trees, such as from different
2700 statements, this flag can usually be left unset.
2702 If OEP_PURE_SAME is set, then pure functions with identical arguments
2703 are considered the same. It is used when the caller has other ways
2704 to ensure that global memory is unchanged in between. */
2706 int
2708 {
2709 /* If either is ERROR_MARK, they aren't equal. */
2713 /* If both types don't have the same signedness, then we can't consider
2714 them equal. We must check this before the STRIP_NOPS calls
2715 because they may change the signedness of the arguments. */
2719 /* If both types don't have the same precision, then it is not safe
2720 to strip NOPs. */
2727 /* In case both args are comparisons but with different comparison
2728 code, try to swap the comparison operands of one arg to produce
2729 a match and compare that variant. */
2733 {
2741 }
2744 /* This is needed for conversions and for COMPONENT_REF.
2745 Might as well play it safe and always test this. */
2751 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2752 We don't care about side effects in that case because the SAVE_EXPR
2753 takes care of that for us. In all other cases, two expressions are
2754 equal if they have no side effects. If we have two identical
2755 expressions with side effects that should be treated the same due
2756 to the only side effects being identical SAVE_EXPR's, that will
2757 be detected in the recursive calls below. */
2763 /* Next handle constant cases, those for which we can return 1 even
2764 if ONLY_CONST is set. */
2767 {
2778 {
2779 /* If we do not distinguish between signed and unsigned zero,
2780 consider them equal. */
2783 }
2787 {
2793 {
2795 flags))
2799 }
2802 }
2806 flags)
2808 flags));
2821 }
2826 /* Define macros to test an operand from arg0 and arg1 for equality and a
2827 variant that allows null and views null as being different from any
2828 non-null value. In the latter case, if either is null, the both
2829 must be; otherwise, do the normal comparison. */
2830 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2831 TREE_OPERAND (arg1, N), flags)
2833 #define OP_SAME_WITH_NULL(N) \
2834 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2835 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2838 {
2840 /* Two conversions are equal only if signedness and modes match. */
2842 {
2852 }
2862 /* For commutative ops, allow the other order. */
2870 /* If either of the pointer (or reference) expressions we are
2871 dereferencing contain a side effect, these cannot be equal. */
2877 {
2887 /* Operands 2 and 3 may be null. */
2894 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2895 may be NULL when we're called to compare MEM_EXPRs. */
2905 }
2909 {
2924 /* Otherwise take into account this is a commutative operation. */
2932 }
2936 {
2938 /* If the CALL_EXPRs call different functions, then they
2939 clearly can not be equal. */
2941 flags))
2944 {
2948 else
2952 }
2954 /* Now see if all the arguments are the same. */
2955 {
2966 /* If we get here and both argument lists are exhausted
2967 then the CALL_EXPRs are equal. */
2969 }
2972 }
2975 /* Consider __builtin_sqrt equal to sqrt. */
2983 }
2985 #undef OP_SAME
2986 #undef OP_SAME_WITH_NULL
2987 }
2988 \f
2989 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2990 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2992 When in doubt, return 0. */
2994 static int
2996 {
3008 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3009 and see if the inner values are the same. This removes any
3010 signedness comparison, which doesn't matter here. */
3017 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3018 actual comparison operand, ARG0.
3020 First throw away any conversions to wider types
3021 already present in the operands. */
3030 {
3033 /* Make sure shorter operand is extended the right way
3034 to match the longer operand. */
3040 }
3043 }
3044 \f
3045 /* See if ARG is an expression that is either a comparison or is performing
3046 arithmetic on comparisons. The comparisons must only be comparing
3047 two different values, which will be stored in *CVAL1 and *CVAL2; if
3048 they are nonzero it means that some operands have already been found.
3049 No variables may be used anywhere else in the expression except in the
3050 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3051 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3053 If this is true, return 1. Otherwise, return zero. */
3055 static int
3057 {
3061 /* We can handle some of the tcc_expression cases here. */
3071 {
3072 /* If we've already found a CVAL1 or CVAL2, this expression is
3073 two complex to handle. */
3079 }
3082 {
3105 /* First see if we can handle the first operand, then the second. For
3106 the second operand, we know *CVAL1 can't be zero. It must be that
3107 one side of the comparison is each of the values; test for the
3108 case where this isn't true by failing if the two operands
3109 are the same. */
3118 ;
3122 ;
3123 else
3127 ;
3131 ;
3132 else
3139 }
3140 }
3141 \f
3142 /* ARG is a tree that is known to contain just arithmetic operations and
3143 comparisons. Evaluate the operations in the tree substituting NEW0 for
3144 any occurrence of OLD0 as an operand of a comparison and likewise for
3145 NEW1 and OLD1. */
3147 static tree
3149 {
3154 /* We can handle some of the tcc_expression cases here. */
3162 {
3177 {
3194 }
3195 /* Fall through - ??? */
3198 {
3202 /* We need to check both for exact equality and tree equality. The
3203 former will be true if the operand has a side-effect. In that
3204 case, we know the operand occurred exactly once. */
3217 }
3221 }
3222 }
3223 \f
3224 /* Return a tree for the case when the result of an expression is RESULT
3225 converted to TYPE and OMITTED was previously an operand of the expression
3226 but is now not needed (e.g., we folded OMITTED * 0).
3228 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3229 the conversion of RESULT to TYPE. */
3231 tree
3233 {
3240 }
3242 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3244 static tree
3246 {
3253 }
3255 /* Return a tree for the case when the result of an expression is RESULT
3256 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3257 of the expression but are now not needed.
3259 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3260 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3261 evaluated before OMITTED2. Otherwise, if neither has side effects,
3262 just do the conversion of RESULT to TYPE. */
3264 tree
3266 {
3275 }
3277 \f
3278 /* Return a simplified tree node for the truth-negation of ARG. This
3279 never alters ARG itself. We assume that ARG is an operation that
3280 returns a truth value (0 or 1).
3282 FIXME: one would think we would fold the result, but it causes
3283 problems with the dominator optimizer. */
3285 tree
3287 {
3291 /* If this is a comparison, we can simply invert it, except for
3292 floating-point non-equality comparisons, in which case we just
3293 enclose a TRUTH_NOT_EXPR around what we have. */
3296 {
3299 && flag_trapping_math
3303 else
3304 {
3309 else
3312 }
3313 }
3316 {
3331 /* Here we can invert either operand. We invert the first operand
3332 unless the second operand is a TRUTH_NOT_EXPR in which case our
3333 result is the XOR of the first operand with the inside of the
3334 negation of the second operand. */
3339 else
3358 {
3361 /* A COND_EXPR may have a throw as one operand, which
3362 then has void type. Just leave void operands
3363 as they are. */
3369 }
3402 }
3405 }
3407 /* Return a simplified tree node for the truth-negation of ARG. This
3408 never alters ARG itself. We assume that ARG is an operation that
3409 returns a truth value (0 or 1).
3411 FIXME: one would think we would fold the result, but it causes
3412 problems with the dominator optimizer. */
3414 tree
3416 {
3417 tree tem;
3427 }
3429 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3430 operands are another bit-wise operation with a common input. If so,
3431 distribute the bit operations to save an operation and possibly two if
3432 constants are involved. For example, convert
3433 (A | B) & (A | C) into A | (B & C)
3434 Further simplification will occur if B and C are constants.
3436 If this optimization cannot be done, 0 will be returned. */
3438 static tree
3440 {
3441 tree common;
3451 {
3455 }
3457 {
3461 }
3463 {
3467 }
3469 {
3473 }
3474 else
3479 }
3481 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3482 with code CODE. This optimization is unsafe. */
3483 static tree
3485 {
3489 /* (A / C) +- (B / C) -> (A +- B) / C. */
3499 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3504 {
3516 }
3519 }
3520 \f
3521 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3522 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3524 static tree
3527 {
3528 tree result;
3531 {
3538 }
3546 }
3548 /* Optimize a bit-field compare.
3550 There are two cases: First is a compare against a constant and the
3551 second is a comparison of two items where the fields are at the same
3552 bit position relative to the start of a chunk (byte, halfword, word)
3553 large enough to contain it. In these cases we can avoid the shift
3554 implicit in bitfield extractions.
3556 For constants, we emit a compare of the shifted constant with the
3557 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3558 compared. For two fields at the same position, we do the ANDs with the
3559 similar mask and compare the result of the ANDs.
3561 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3562 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3563 are the left and right operands of the comparison, respectively.
3565 If the optimization described above can be done, we return the resulting
3566 tree. Otherwise we return zero. */
3568 static tree
3571 {
3580 tree mask;
3581 tree offset;
3583 /* Get all the information about the extractions being done. If the bit size
3584 if the same as the size of the underlying object, we aren't doing an
3585 extraction at all and so can do nothing. We also don't want to
3586 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3587 then will no longer be able to replace it. */
3595 {
3596 /* If this is not a constant, we can only do something if bit positions,
3597 sizes, and signedness are the same. */
3605 }
3607 /* See if we can find a mode to refer to this field. We should be able to,
3608 but fail if we can't. */
3617 /* Set signed and unsigned types of the precision of this mode for the
3618 shifts below. */
3622 /* Compute the bit position and size for the new reference and our offset
3623 within it. If the new reference is the same size as the original, we
3624 won't optimize anything, so return zero. */
3634 /* Make the mask to be used against the extracted field. */
3641 /* If not comparing with constant, just rework the comparison
3642 and return. */
3646 unsigned_type,
3649 mask),
3652 unsigned_type,
3655 mask));
3657 /* Otherwise, we are handling the constant case. See if the constant is too
3658 big for the field. Warn and return a tree of for 0 (false) if so. We do
3659 this not only for its own sake, but to avoid having to test for this
3660 error case below. If we didn't, we might generate wrong code.
3662 For unsigned fields, the constant shifted right by the field length should
3663 be all zero. For signed fields, the high-order bits should agree with
3664 the sign bit. */
3667 {
3671 {
3675 }
3676 }
3677 else
3678 {
3682 {
3686 }
3687 }
3689 /* Single-bit compares should always be against zero. */
3691 {
3694 }
3696 /* Make a new bitfield reference, shift the constant over the
3697 appropriate number of bits and mask it with the computed mask
3698 (in case this was a signed field). If we changed it, make a new one. */
3701 {
3704 }
3714 rhs);
3715 }
3716 \f
3717 /* Subroutine for fold_truthop: decode a field reference.
3719 If EXP is a comparison reference, we return the innermost reference.
3721 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3722 set to the starting bit number.
3724 If the innermost field can be completely contained in a mode-sized
3725 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3727 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3728 otherwise it is not changed.
3730 *PUNSIGNEDP is set to the signedness of the field.
3732 *PMASK is set to the mask used. This is either contained in a
3733 BIT_AND_EXPR or derived from the width of the field.
3735 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3737 Return 0 if this is not a component reference or is one that we can't
3738 do anything with. */
3740 static tree
3745 {
3749 tree unsigned_type;
3752 /* All the optimizations using this function assume integer fields.
3753 There are problems with FP fields since the type_for_size call
3754 below can fail for, e.g., XFmode. */
3758 /* We are interested in the bare arrangement of bits, so strip everything
3759 that doesn't affect the machine mode. However, record the type of the
3760 outermost expression if it may matter below. */
3768 {
3774 }
3783 /* If the number of bits in the reference is the same as the bitsize of
3784 the outer type, then the outer type gives the signedness. Otherwise
3785 (in case of a small bitfield) the signedness is unchanged. */
3789 /* Compute the mask to access the bitfield. */
3798 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3806 }
3808 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3809 bit positions. */
3811 static int
3813 {
3816 tree tmask;
3820 return
3827 }
3829 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3830 represents the sign bit of EXP's type. If EXP represents a sign
3831 or zero extension, also test VAL against the unextended type.
3832 The return value is the (sub)expression whose sign bit is VAL,
3833 or NULL_TREE otherwise. */
3835 static tree
3837 {
3841 tree t;
3843 /* Tree EXP must have an integral type. */
3848 /* Tree VAL must be an integer constant. */
3855 {
3862 }
3863 else
3864 {
3871 }
3873 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3874 treat VAL as if it were unsigned. */
3879 /* Handle extension from a narrower type. */
3885 }
3887 /* Subroutine for fold_truthop: determine if an operand is simple enough
3888 to be evaluated unconditionally. */
3890 static int
3892 {
3893 /* Strip any conversions that don't change the machine mode. */
3902 /* Don't regard global variables as simple. They may be
3903 allocated in ways unknown to the compiler (shared memory,
3904 #pragma weak, etc). */
3907 /* Loading a static variable is unduly expensive, but global
3908 registers aren't expensive. */
3910 }
3911 \f
3912 /* The following functions are subroutines to fold_range_test and allow it to
3913 try to change a logical combination of comparisons into a range test.
3915 For example, both
3916 X == 2 || X == 3 || X == 4 || X == 5
3917 and
3918 X >= 2 && X <= 5
3919 are converted to
3920 (unsigned) (X - 2) <= 3
3922 We describe each set of comparisons as being either inside or outside
3923 a range, using a variable named like IN_P, and then describe the
3924 range with a lower and upper bound. If one of the bounds is omitted,
3925 it represents either the highest or lowest value of the type.
3927 In the comments below, we represent a range by two numbers in brackets
3928 preceded by a "+" to designate being inside that range, or a "-" to
3929 designate being outside that range, so the condition can be inverted by
3930 flipping the prefix. An omitted bound is represented by a "-". For
3931 example, "- [-, 10]" means being outside the range starting at the lowest
3932 possible value and ending at 10, in other words, being greater than 10.
3933 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3934 always false.
3936 We set up things so that the missing bounds are handled in a consistent
3937 manner so neither a missing bound nor "true" and "false" need to be
3938 handled using a special case. */
3940 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3941 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3942 and UPPER1_P are nonzero if the respective argument is an upper bound
3943 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3944 must be specified for a comparison. ARG1 will be converted to ARG0's
3945 type if both are specified. */
3947 static tree
3950 {
3951 tree tem;
3955 /* If neither arg represents infinity, do the normal operation.
3956 Else, if not a comparison, return infinity. Else handle the special
3957 comparison rules. Note that most of the cases below won't occur, but
3958 are handled for consistency. */
3961 {
3966 }
3971 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3972 for neither. In real maths, we cannot assume open ended ranges are
3973 the same. But, this is computer arithmetic, where numbers are finite.
3974 We can therefore make the transformation of any unbounded range with
3975 the value Z, Z being greater than any representable number. This permits
3976 us to treat unbounded ranges as equal. */
3980 {
4001 }
4004 }
4005 \f
4006 /* Given EXP, a logical expression, set the range it is testing into
4007 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4008 actually being tested. *PLOW and *PHIGH will be made of the same
4009 type as the returned expression. If EXP is not a comparison, we
4010 will most likely not be returning a useful value and range. Set
4011 *STRICT_OVERFLOW_P to true if the return value is only valid
4012 because signed overflow is undefined; otherwise, do not change
4013 *STRICT_OVERFLOW_P. */
4015 static tree
4018 {
4025 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4026 and see if we can refine the range. Some of the cases below may not
4027 happen, but it doesn't seem worth worrying about this. We "continue"
4028 the outer loop when we've changed something; otherwise we "break"
4029 the switch, which will "break" the while. */
4035 {
4040 {
4052 }
4055 {
4062 /* We can only do something if the range is testing for zero
4063 and if the second operand is an integer constant. Note that
4064 saying something is "in" the range we make is done by
4065 complementing IN_P since it will set in the initial case of
4066 being not equal to zero; "out" is leaving it alone. */
4073 {
4094 }
4096 /* If this is an unsigned comparison, we also know that EXP is
4097 greater than or equal to zero. We base the range tests we make
4098 on that fact, so we record it here so we can parse existing
4099 range tests. We test arg0_type since often the return type
4100 of, e.g. EQ_EXPR, is boolean. */
4102 {
4106 NULL_TREE))
4111 /* If the high bound is missing, but we have a nonzero low
4112 bound, reverse the range so it goes from zero to the low bound
4113 minus 1. */
4115 {
4120 }
4121 }
4127 /* (-x) IN [a,b] -> x in [-b, -a] */
4139 /* ~ X -> -X - 1 */
4148 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4149 move a constant to the other side. */
4154 /* If EXP is signed, any overflow in the computation is undefined,
4155 so we don't worry about it so long as our computations on
4156 the bounds don't overflow. For unsigned, overflow is defined
4157 and this is exactly the right thing. */
4169 /* Check for an unsigned range which has wrapped around the maximum
4170 value thus making n_high < n_low, and normalize it. */
4172 {
4178 /* If the range is of the form +/- [ x+1, x ], we won't
4179 be able to normalize it. But then, it represents the
4180 whole range or the empty set, so make it
4181 +/- [ -, - ]. */
4185 else
4187 }
4188 else
4212 /* If we're converting arg0 from an unsigned type, to exp,
4213 a signed type, we will be doing the comparison as unsigned.
4214 The tests above have already verified that LOW and HIGH
4215 are both positive.
4217 So we have to ensure that we will handle large unsigned
4218 values the same way that the current signed bounds treat
4219 negative values. */
4222 {
4223 tree high_positive;
4227 /* A range without an upper bound is, naturally, unbounded.
4228 Since convert would have cropped a very large value, use
4229 the max value for the destination type. */
4230 high_positive
4237 high_positive),
4240 /* If the low bound is specified, "and" the range with the
4241 range for which the original unsigned value will be
4242 positive. */
4244 {
4248 integer_zero_node),
4249 high_positive))
4253 }
4254 else
4255 {
4256 /* Otherwise, "or" the range with the range of the input
4257 that will be interpreted as negative. */
4261 integer_zero_node),
4262 high_positive))
4266 }
4267 }
4275 }
4278 }
4280 /* If EXP is a constant, we can evaluate whether this is true or false. */
4282 {
4289 }
4293 }
4294 \f
4295 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4296 type, TYPE, return an expression to test if EXP is in (or out of, depending
4297 on IN_P) the range. Return 0 if the test couldn't be created. */
4299 static tree
4301 {
4303 tree value;
4305 #ifdef HAVE_canonicalize_funcptr_for_compare
4306 /* Disable this optimization for function pointer expressions
4307 on targets that require function pointer canonicalization. */
4312 #endif
4315 {
4321 }
4339 {
4341 {
4345 }
4347 }
4349 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4351 {
4353 HOST_WIDE_INT hi;
4358 {
4361 }
4362 else
4363 {
4366 }
4369 {
4371 {
4374 }
4377 }
4378 }
4380 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4381 This requires wrap-around arithmetics for the type of the expression. */
4383 {
4385 /* There is no requirement that LOW be within the range of ETYPE
4386 if the latter is a subtype. It must, however, be within the base
4387 type of ETYPE. So be sure we do the subtraction in that type. */
4400 }
4402 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4405 {
4408 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4409 for the type in question, as we rely on this here. */
4419 else
4421 }
4435 }
4436 \f
4437 /* Return the predecessor of VAL in its type, handling the infinite case. */
4439 static tree
4441 {
4447 else
4449 }
4451 /* Return the successor of VAL in its type, handling the infinite case. */
4453 static tree
4455 {
4461 else
4463 }
4465 /* Given two ranges, see if we can merge them into one. Return 1 if we
4466 can, 0 if we can't. Set the output range into the specified parameters. */
4468 static int
4471 {
4475 tree tem;
4485 /* Make range 0 be the range that starts first, or ends last if they
4486 start at the same value. Swap them if it isn't. */
4489 || (lowequal
4492 {
4496 }
4498 /* Now flag two cases, whether the ranges are disjoint or whether the
4499 second range is totally subsumed in the first. Note that the tests
4500 below are simplified by the ones above. */
4506 /* We now have four cases, depending on whether we are including or
4507 excluding the two ranges. */
4509 {
4510 /* If they don't overlap, the result is false. If the second range
4511 is a subset it is the result. Otherwise, the range is from the start
4512 of the second to the end of the first. */
4517 else
4519 }
4522 {
4523 /* If they don't overlap, the result is the first range. If they are
4524 equal, the result is false. If the second range is a subset of the
4525 first, and the ranges begin at the same place, we go from just after
4526 the end of the second range to the end of the first. If the second
4527 range is not a subset of the first, or if it is a subset and both
4528 ranges end at the same place, the range starts at the start of the
4529 first range and ends just before the second range.
4530 Otherwise, we can't describe this as a single range. */
4536 {
4540 }
4542 {
4546 }
4547 else
4549 }
4552 {
4553 /* If they don't overlap, the result is the second range. If the second
4554 is a subset of the first, the result is false. Otherwise,
4555 the range starts just after the first range and ends at the
4556 end of the second. */
4561 else
4562 {
4566 }
4567 }
4569 else
4570 {
4571 /* The case where we are excluding both ranges. Here the complex case
4572 is if they don't overlap. In that case, the only time we have a
4573 range is if they are adjacent. If the second is a subset of the
4574 first, the result is the first. Otherwise, the range to exclude
4575 starts at the beginning of the first range and ends at the end of the
4576 second. */
4578 {
4583 else
4584 {
4585 /* Canonicalize - [min, x] into - [-, x]. */
4588 {
4593 /* FALLTHROUGH */
4606 }
4608 /* Canonicalize - [x, max] into - [x, -]. */
4611 {
4616 /* FALLTHROUGH */
4631 }
4633 /* The ranges might be also adjacent between the maximum and
4634 minimum values of the given type. For
4635 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4636 return + [x + 1, y - 1]. */
4638 {
4645 }
4646 else
4648 }
4649 }
4652 else
4654 }
4658 }
4659 \f
4661 /* Subroutine of fold, looking inside expressions of the form
4662 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4663 of the COND_EXPR. This function is being used also to optimize
4664 A op B ? C : A, by reversing the comparison first.
4666 Return a folded expression whose code is not a COND_EXPR
4667 anymore, or NULL_TREE if no folding opportunity is found. */
4669 static tree
4671 {
4676 tree tem;
4681 /* If we have A op 0 ? A : -A, consider applying the following
4682 transformations:
4684 A == 0? A : -A same as -A
4685 A != 0? A : -A same as A
4686 A >= 0? A : -A same as abs (A)
4687 A > 0? A : -A same as abs (A)
4688 A <= 0? A : -A same as -abs (A)
4689 A < 0? A : -A same as -abs (A)
4691 None of these transformations work for modes with signed
4692 zeros. If A is +/-0, the first two transformations will
4693 change the sign of the result (from +0 to -0, or vice
4694 versa). The last four will fix the sign of the result,
4695 even though the original expressions could be positive or
4696 negative, depending on the sign of A.
4698 Note that all these transformations are correct if A is
4699 NaN, since the two alternatives (A and -A) are also NaNs. */
4705 /* In the case that A is of the form X-Y, '-A' (arg2) may
4706 have already been folded to Y-X, check for that. */
4714 {
4726 /* Fall through. */
4748 }
4750 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4751 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4752 both transformations are correct when A is NaN: A != 0
4753 is then true, and A == 0 is false. */
4756 {
4761 }
4763 /* Try some transformations of A op B ? A : B.
4765 A == B? A : B same as B
4766 A != B? A : B same as A
4767 A >= B? A : B same as max (A, B)
4768 A > B? A : B same as max (B, A)
4769 A <= B? A : B same as min (A, B)
4770 A < B? A : B same as min (B, A)
4772 As above, these transformations don't work in the presence
4773 of signed zeros. For example, if A and B are zeros of
4774 opposite sign, the first two transformations will change
4775 the sign of the result. In the last four, the original
4776 expressions give different results for (A=+0, B=-0) and
4777 (A=-0, B=+0), but the transformed expressions do not.
4779 The first two transformations are correct if either A or B
4780 is a NaN. In the first transformation, the condition will
4781 be false, and B will indeed be chosen. In the case of the
4782 second transformation, the condition A != B will be true,
4783 and A will be chosen.
4785 The conversions to max() and min() are not correct if B is
4786 a number and A is not. The conditions in the original
4787 expressions will be false, so all four give B. The min()
4788 and max() versions would give a NaN instead. */
4790 /* Avoid these transformations if the COND_EXPR may be used
4791 as an lvalue in the C++ front-end. PR c++/19199. */
4792 && (in_gimple_form
4797 {
4802 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4804 {
4808 }
4811 {
4820 /* In C++ a ?: expression can be an lvalue, so put the
4821 operand which will be used if they are equal first
4822 so that we can convert this back to the
4823 corresponding COND_EXPR. */
4825 {
4832 }
4839 {
4846 }
4859 }
4860 }
4862 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4863 we might still be able to simplify this. For example,
4864 if C1 is one less or one more than C2, this might have started
4865 out as a MIN or MAX and been transformed by this function.
4866 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4872 {
4874 /* We can replace A with C1 in this case. */
4879 /* If C1 is C2 + 1, this is min(A, C2). */
4881 OEP_ONLY_CONST)
4885 OEP_ONLY_CONST))
4891 /* If C1 is C2 - 1, this is min(A, C2). */
4893 OEP_ONLY_CONST)
4897 OEP_ONLY_CONST))
4903 /* If C1 is C2 - 1, this is max(A, C2). */
4905 OEP_ONLY_CONST)
4909 OEP_ONLY_CONST))
4915 /* If C1 is C2 + 1, this is max(A, C2). */
4917 OEP_ONLY_CONST)
4921 OEP_ONLY_CONST))
4929 }
4932 }
4935 \f
4936 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4937 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4938 #endif
4940 /* EXP is some logical combination of boolean tests. See if we can
4941 merge it into some range test. Return the new tree if so. */
4943 static tree
4945 {
4953 tree tem;
4957 /* If this is an OR operation, invert both sides; we will invert
4958 again at the end. */
4962 /* If both expressions are the same, if we can merge the ranges, and we
4963 can build the range test, return it or it inverted. If one of the
4964 ranges is always true or always false, consider it to be the same
4965 expression as the other. */
4973 {
4977 }
4979 /* On machines where the branch cost is expensive, if this is a
4980 short-circuited branch and the underlying object on both sides
4981 is the same, make a non-short-circuit operation. */
4987 {
4988 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4989 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4990 which cases we can't do this. */
4998 {
5007 {
5010 WARN_STRICT_OVERFLOW_COMPARISON);
5014 }
5015 }
5016 }
5019 }
5020 \f
5021 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5022 bit value. Arrange things so the extra bits will be set to zero if and
5023 only if C is signed-extended to its full width. If MASK is nonzero,
5024 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5026 static tree
5028 {
5031 tree temp;
5036 /* We work by getting just the sign bit into the low-order bit, then
5037 into the high-order bit, then sign-extend. We then XOR that value
5038 with C. */
5042 /* We must use a signed type in order to get an arithmetic right shift.
5043 However, we must also avoid introducing accidental overflows, so that
5044 a subsequent call to integer_zerop will work. Hence we must
5045 do the type conversion here. At this point, the constant is either
5046 zero or one, and the conversion to a signed type can never overflow.
5047 We could get an overflow if this conversion is done anywhere else. */
5056 /* If necessary, convert the type back to match the type of C. */
5061 }
5062 \f
5063 /* Find ways of folding logical expressions of LHS and RHS:
5064 Try to merge two comparisons to the same innermost item.
5065 Look for range tests like "ch >= '0' && ch <= '9'".
5066 Look for combinations of simple terms on machines with expensive branches
5067 and evaluate the RHS unconditionally.
5069 For example, if we have p->a == 2 && p->b == 4 and we can make an
5070 object large enough to span both A and B, we can do this with a comparison
5071 against the object ANDed with the a mask.
5073 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5074 operations to do this with one comparison.
5076 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5077 function and the one above.
5079 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5080 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5082 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5083 two operands.
5085 We return the simplified tree or 0 if no optimization is possible. */
5087 static tree
5089 {
5090 /* If this is the "or" of two comparisons, we can do something if
5091 the comparisons are NE_EXPR. If this is the "and", we can do something
5092 if the comparisons are EQ_EXPR. I.e.,
5093 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5095 WANTED_CODE is this operation code. For single bit fields, we can
5096 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5097 comparison for one-bit fields. */
5119 /* Start by getting the comparison codes. Fail if anything is volatile.
5120 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5121 it were surrounded with a NE_EXPR. */
5130 {
5134 }
5137 {
5141 }
5152 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5155 {
5156 tree result;
5159 {
5164 }
5167 {
5173 }
5174 }
5179 /* If the RHS can be evaluated unconditionally and its operands are
5180 simple, it wins to evaluate the RHS unconditionally on machines
5181 with expensive branches. In this case, this isn't a comparison
5182 that can be merged. Avoid doing this if the RHS is a floating-point
5183 comparison since those can trap. */
5189 {
5190 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5200 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5211 {
5215 }
5216 }
5218 /* See if the comparisons can be merged. Then get all the parameters for
5219 each side. */
5243 /* It must be true that the inner operation on the lhs of each
5244 comparison must be the same if we are to be able to do anything.
5245 Then see if we have constants. If not, the same must be true for
5246 the rhs's. */
5257 else
5260 /* If either comparison code is not correct for our logical operation,
5261 fail. However, we can convert a one-bit comparison against zero into
5262 the opposite comparison against that bit being set in the field. */
5266 {
5268 {
5269 /* Make the left operand unsigned, since we are only interested
5270 in the value of one bit. Otherwise we are doing the wrong
5271 thing below. */
5274 }
5275 else
5277 }
5279 /* This is analogous to the code for l_const above. */
5281 {
5283 {
5286 }
5287 else
5289 }
5291 /* See if we can find a mode that contains both fields being compared on
5292 the left. If we can't, fail. Otherwise, update all constants and masks
5293 to be relative to a field of that size. */
5298 volatilep);
5308 {
5311 }
5319 {
5327 {
5331 }
5332 }
5334 {
5342 {
5346 }
5347 }
5349 /* If the right sides are not constant, do the same for it. Also,
5350 disallow this optimization if a size or signedness mismatch occurs
5351 between the left and right sides. */
5353 {
5356 /* Make sure the two fields on the right
5357 correspond to the left without being swapped. */
5365 volatilep);
5375 {
5378 }
5385 /* Make a mask that corresponds to both fields being compared.
5386 Do this for both items being compared. If the operands are the
5387 same size and the bits being compared are in the same position
5388 then we can do this by masking both and comparing the masked
5389 results. */
5393 {
5405 }
5407 /* There is still another way we can do something: If both pairs of
5408 fields being compared are adjacent, we may be able to make a wider
5409 field containing them both.
5411 Note that we still must mask the lhs/rhs expressions. Furthermore,
5412 the mask must be shifted to account for the shift done by
5413 make_bit_field_ref. */
5418 {
5419 tree type;
5431 /* Convert to the smaller type before masking out unwanted bits. */
5434 {
5436 {
5440 }
5442 {
5446 }
5447 }
5456 }
5459 }
5461 /* Handle the case of comparisons with constants. If there is something in
5462 common between the masks, those bits of the constants must be the same.
5463 If not, the condition is always false. Test for this to avoid generating
5464 incorrect code below. */
5469 {
5471 {
5474 }
5475 else
5476 {
5479 }
5480 }
5482 /* Construct the expression we will return. First get the component
5483 reference we will make. Unless the mask is all ones the width of
5484 that field, perform the mask operation. Then compare with the
5485 merged constant. */
5495 }
5496 \f
5497 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5498 constant. */
5500 static tree
5502 {
5506 tree minmax_const;
5508 tree inner;
5518 /* If something does not permit us to optimize, return the original tree. */
5526 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5527 and GT_EXPR, doing the rest with recursive calls using logical
5528 simplifications. */
5530 {
5532 {
5538 }
5541 return
5543 optimize_minmax_comparison
5545 optimize_minmax_comparison
5550 /* MAX (X, 0) == 0 -> X <= 0 */
5554 /* MAX (X, 0) == 5 -> X == 5 */
5558 /* MAX (X, 0) == -1 -> false */
5562 /* MIN (X, 0) == 0 -> X >= 0 */
5566 /* MIN (X, 0) == 5 -> false */
5569 else
5570 /* MIN (X, 0) == -1 -> X == -1 */
5575 /* MAX (X, 0) > 0 -> X > 0
5576 MAX (X, 0) > 5 -> X > 5 */
5580 /* MAX (X, 0) > -1 -> true */
5584 /* MIN (X, 0) > 0 -> false
5585 MIN (X, 0) > 5 -> false */
5588 else
5589 /* MIN (X, 0) > -1 -> X > -1 */
5594 }
5595 }
5596 \f
5597 /* T is an integer expression that is being multiplied, divided, or taken a
5598 modulus (CODE says which and what kind of divide or modulus) by a
5599 constant C. See if we can eliminate that operation by folding it with
5600 other operations already in T. WIDE_TYPE, if non-null, is a type that
5601 should be used for the computation if wider than our type.
5603 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5604 (X * 2) + (Y * 4). We must, however, be assured that either the original
5605 expression would not overflow or that overflow is undefined for the type
5606 in the language in question.
5608 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5609 the machine has a multiply-accumulate insn or that this is part of an
5610 addressing calculation.
5612 If we return a non-null expression, it is an equivalent form of the
5613 original computation, but need not be in the original type.
5615 We set *STRICT_OVERFLOW_P to true if the return values depends on
5616 signed overflow being undefined. Otherwise we do not change
5617 *STRICT_OVERFLOW_P. */
5619 static tree
5622 {
5623 /* To avoid exponential search depth, refuse to allow recursion past
5624 three levels. Beyond that (1) it's highly unlikely that we'll find
5625 something interesting and (2) we've probably processed it before
5626 when we built the inner expression. */
5629 tree ret;
5634 depth++;
5636 depth--;
5639 }
5641 static tree
5644 {
5655 /* Don't deal with constants of zero here; they confuse the code below. */
5665 /* Note that we need not handle conditional operations here since fold
5666 already handles those cases. So just do arithmetic here. */
5668 {
5670 /* For a constant, we can always simplify if we are a multiply
5671 or (for divide and modulus) if it is a multiple of our constant. */
5679 /* If op0 is an expression ... */
5685 /* ... and is unsigned, and its type is smaller than ctype,
5686 then we cannot pass through as widening. */
5692 /* ... or this is a truncation (t is narrower than op0),
5693 then we cannot pass through this narrowing. */
5696 /* ... or signedness changes for division or modulus,
5697 then we cannot pass through this conversion. */
5703 /* Pass the constant down and see if we can make a simplification. If
5704 we can, replace this expression with the inner simplification for
5705 possible later conversion to our or some other type. */
5710 code == MULT_EXPR
5712 strict_overflow_p))))
5717 /* If widening the type changes it from signed to unsigned, then we
5718 must avoid building ABS_EXPR itself as unsigned. */
5720 {
5724 {
5727 }
5729 }
5730 /* FALLTHROUGH */
5738 /* If widening the type changes the signedness, then we can't perform
5739 this optimization as that changes the result. */
5743 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5749 {
5756 }
5760 /* If the second operand is constant, this is a multiplication
5761 or floor division, by a power of two, so we can treat it that
5762 way unless the multiplier or divisor overflows. Signed
5763 left-shift overflow is implementation-defined rather than
5764 undefined in C90, so do not convert signed left shift into
5765 multiplication. */
5768 /* const_binop may not detect overflow correctly,
5769 so check for it explicitly here. */
5774 size_one_node,
5784 /* See if we can eliminate the operation on both sides. If we can, we
5785 can return a new PLUS or MINUS. If we can't, the only remaining
5786 cases where we can do anything are if the second operand is a
5787 constant. */
5793 /* If not multiplication, we can only do this if both operands
5794 are divisible by c. */
5797 {
5802 }
5804 /* If this was a subtraction, negate OP1 and set it to be an addition.
5805 This simplifies the logic below. */
5812 /* If either OP1 or C are negative, this optimization is not safe for
5813 some of the division and remainder types while for others we need
5814 to change the code. */
5816 {
5824 }
5826 /* If it's a multiply or a division/modulus operation of a multiple
5827 of our constant, do the operation and verify it doesn't overflow. */
5830 {
5833 /* We allow the constant to overflow with wrapping semantics. */
5837 }
5838 else
5841 /* If we have an unsigned type is not a sizetype, we cannot widen
5842 the operation since it will change the result if the original
5843 computation overflowed. */
5849 /* If we were able to eliminate our operation from the first side,
5850 apply our operation to the second side and reform the PLUS. */
5854 /* The last case is if we are a multiply. In that case, we can
5855 apply the distributive law to commute the multiply and addition
5856 if the multiplication of the constants doesn't overflow. */
5862 op1);
5867 /* We have a special case here if we are doing something like
5868 (C * 8) % 4 since we know that's zero. */
5875 /* ... fall through ... */
5879 /* If we can extract our operation from the LHS, do so and return a
5880 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5881 do something only if the second operand is a constant. */
5895 /* If these are the same operation types, we can associate them
5896 assuming no overflow. */
5903 /* If these operations "cancel" each other, we have the main
5904 optimizations of this pass, which occur when either constant is a
5905 multiple of the other, in which case we replace this with either an
5906 operation or CODE or TCODE.
5908 If we have an unsigned type that is not a sizetype, we cannot do
5909 this since it will change the result if the original computation
5910 overflowed. */
5917 {
5919 {
5926 }
5928 {
5935 }
5936 }
5941 }
5944 }
5945 \f
5946 /* Return a node which has the indicated constant VALUE (either 0 or
5947 1), and is of the indicated TYPE. */
5949 tree
5951 {
5956 else
5958 }
5961 /* Return true if expr looks like an ARRAY_REF and set base and
5962 offset to the appropriate trees. If there is no offset,
5963 offset is set to NULL_TREE. Base will be canonicalized to
5964 something you can get the element type from using
5965 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5966 in bytes to the base. */
5968 static bool
5970 {
5971 /* One canonical form is a PLUS_EXPR with the first
5972 argument being an ADDR_EXPR with a possible NOP_EXPR
5973 attached. */
5975 {
5978 /* Strip NOP_EXPRs here because the C frontends and/or
5979 folders present us (int *)&x.a + 4B possibly. */
5982 {
5986 else
5990 }
5991 }
5992 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5993 which we transform into an ADDR_EXPR with appropriate
5994 offset. For other arguments to the ADDR_EXPR we assume
5995 zero offset and as such do not care about the ADDR_EXPR
5996 type and strip possible nops from it. */
5998 {
6001 {
6006 }
6007 else
6008 {
6009 /* Handle array-to-pointer decay as &a. */
6012 else
6015 }
6017 }
6018 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
6021 {
6025 }
6028 }
6031 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6032 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6033 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6034 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6035 COND is the first argument to CODE; otherwise (as in the example
6036 given here), it is the second argument. TYPE is the type of the
6037 original expression. Return NULL_TREE if no simplification is
6038 possible. */
6040 static tree
6044 {
6051 /* This transformation is only worthwhile if we don't have to wrap
6052 arg in a SAVE_EXPR, and the operation can be simplified on at least
6053 one of the branches once its pushed inside the COND_EXPR. */
6058 {
6062 /* If this operand throws an expression, then it does not make
6063 sense to try to perform a logical or arithmetic operation
6064 involving it. */
6069 }
6070 else
6071 {
6076 }
6080 {
6084 else
6086 }
6088 {
6092 else
6094 }
6098 }
6100 \f
6101 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6103 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6104 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6105 ADDEND is the same as X.
6107 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6108 and finite. The problematic cases are when X is zero, and its mode
6109 has signed zeros. In the case of rounding towards -infinity,
6110 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6111 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6113 static bool
6115 {
6119 /* Don't allow the fold with -fsignaling-nans. */
6123 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6127 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6132 /* The mode has signed zeros, and we have to honor their sign.
6133 In this situation, there is only one case we can return true for.
6134 X - 0 is the same as X unless rounding towards -infinity is
6135 supported. */
6137 }
6139 /* Subroutine of fold() that checks comparisons of built-in math
6140 functions against real constants.
6142 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6143 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6144 is the type of the result and ARG0 and ARG1 are the operands of the
6145 comparison. ARG1 must be a TREE_REAL_CST.
6147 The function returns the constant folded tree if a simplification
6148 can be made, and NULL_TREE otherwise. */
6150 static tree
6153 {
6154 REAL_VALUE_TYPE c;
6157 {
6163 {
6164 /* sqrt(x) < y is always false, if y is negative. */
6168 /* sqrt(x) > y is always true, if y is negative and we
6169 don't care about NaNs, i.e. negative values of x. */
6173 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6176 }
6178 {
6179 REAL_VALUE_TYPE c2;
6185 {
6186 /* sqrt(x) > y is x == +Inf, when y is very large. */
6191 /* sqrt(x) > y is always false, when y is very large
6192 and we don't care about infinities. */
6194 }
6196 /* sqrt(x) > c is the same as x > c*c. */
6199 }
6201 {
6202 REAL_VALUE_TYPE c2;
6208 {
6209 /* sqrt(x) < y is always true, when y is a very large
6210 value and we don't care about NaNs or Infinities. */
6214 /* sqrt(x) < y is x != +Inf when y is very large and we
6215 don't care about NaNs. */
6220 /* sqrt(x) < y is x >= 0 when y is very large and we
6221 don't care about Infinities. */
6226 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6235 dconst0)),
6238 c2)));
6239 }
6241 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6246 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6249 {
6254 dconst0)),
6257 c2)));
6258 }
6259 }
6260 }
6263 }
6265 /* Subroutine of fold() that optimizes comparisons against Infinities,
6266 either +Inf or -Inf.
6268 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6269 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6270 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6272 The function returns the constant folded tree if a simplification
6273 can be made, and NULL_TREE otherwise. */
6275 static tree
6277 {
6279 REAL_VALUE_TYPE max;
6280 tree temp;
6285 /* For negative infinity swap the sense of the comparison. */
6291 {
6293 /* x > +Inf is always false, if with ignore sNANs. */
6299 /* x <= +Inf is always true, if we don't case about NaNs. */
6303 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6306 {
6309 }
6314 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6320 /* x < +Inf is always equal to x <= DBL_MAX. */
6326 /* x != +Inf is always equal to !(x > DBL_MAX). */
6338 }
6341 }
6343 /* Subroutine of fold() that optimizes comparisons of a division by
6344 a nonzero integer constant against an integer constant, i.e.
6345 X/C1 op C2.
6347 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6348 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6349 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6351 The function returns the constant folded tree if a simplification
6352 can be made, and NULL_TREE otherwise. */
6354 static tree
6356 {
6361 HOST_WIDE_INT hpart;
6366 /* We have to do this the hard way to detect unsigned overflow.
6367 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6378 {
6383 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6391 }
6393 {
6397 {
6416 }
6417 }
6418 else
6419 {
6420 /* A negative divisor reverses the relational operators. */
6426 {
6445 }
6446 }
6449 {
6470 {
6473 }
6478 {
6481 }
6486 {
6489 }
6494 {
6497 }
6502 }
6505 }
6508 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6509 equality/inequality test, then return a simplified form of the test
6510 using a sign testing. Otherwise return NULL. TYPE is the desired
6511 result type. */
6513 static tree
6515 tree result_type)
6516 {
6517 /* If this is testing a single bit, we can optimize the test. */
6521 {
6522 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6523 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6527 /* This is only a win if casting to a signed type is cheap,
6528 i.e. when arg00's type is not a partial mode. */
6531 {
6536 }
6537 }
6540 }
6542 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6543 equality/inequality test, then return a simplified form of
6544 the test using shifts and logical operations. Otherwise return
6545 NULL. TYPE is the desired result type. */
6547 tree
6549 tree result_type)
6550 {
6551 /* If this is testing a single bit, we can optimize the test. */
6555 {
6564 /* First, see if we can fold the single bit test into a sign-bit
6565 test. */
6567 result_type);
6571 /* Otherwise we have (A & C) != 0 where C is a single bit,
6572 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6573 Similarly for (A & C) == 0. */
6575 /* If INNER is a right shift of a constant and it plus BITNUM does
6576 not overflow, adjust BITNUM and INNER. */
6583 {
6586 }
6588 /* If we are going to be able to omit the AND below, we must do our
6589 operations as unsigned. If we must use the AND, we have a choice.
6590 Normally unsigned is faster, but for some machines signed is. */
6591 #ifdef LOAD_EXTEND_OP
6594 #else
6596 #endif
6612 /* Put the AND last so it can combine with more things. */
6615 /* Make sure to return the proper type. */
6619 }
6621 }
6623 /* Check whether we are allowed to reorder operands arg0 and arg1,
6624 such that the evaluation of arg1 occurs before arg0. */
6626 static bool
6628 {
6635 }
6637 /* Test whether it is preferable two swap two operands, ARG0 and
6638 ARG1, for example because ARG0 is an integer constant and ARG1
6639 isn't. If REORDER is true, only recommend swapping if we can
6640 evaluate the operands in reverse order. */
6642 bool
6644 {
6675 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6676 for commutative and comparison operators. Ensuring a canonical
6677 form allows the optimizers to find additional redundancies without
6678 having to explicitly check for both orderings. */
6684 /* Put SSA_NAMEs last. */
6690 /* Put variables last. */
6697 }
6699 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6700 ARG0 is extended to a wider type. */
6702 static tree
6704 {
6706 tree arg1_unw;
6715 #ifdef HAVE_canonicalize_funcptr_for_compare
6716 /* Disable this optimization if we're casting a function pointer
6717 type on targets that require function pointer canonicalization. */
6722 #endif
6729 /* If possible, express the comparison in the shorter mode. */
6745 /* If we are comparing with the integer that does not fit into the range
6746 of the shorter type, the result is known. */
6757 {
6784 }
6787 }
6789 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6790 ARG0 just the signedness is changed. */
6792 static tree
6795 {
6796 tree arg0_inner;
6807 #ifdef HAVE_canonicalize_funcptr_for_compare
6808 /* Disable this optimization if we're casting a function pointer
6809 type on targets that require function pointer canonicalization. */
6814 #endif
6834 else
6838 }
6840 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6841 step of the array. Reconstructs s and delta in the case of s * delta
6842 being an integer constant (and thus already folded).
6843 ADDR is the address. MULT is the multiplicative expression.
6844 If the function succeeds, the new address expression is returned. Otherwise
6845 NULL_TREE is returned. */
6847 static tree
6849 {
6853 tree itype;
6856 /* Canonicalize op1 into a possibly non-constant delta
6857 and an INTEGER_CST s. */
6859 {
6866 {
6869 }
6871 {
6874 }
6875 else
6877 }
6879 {
6882 }
6883 else
6884 {
6885 /* Simulate we are delta * 1. */
6888 }
6891 {
6893 {
6894 /* Remember if this was a multi-dimensional array. */
6907 {
6910 }
6911 else
6912 {
6913 /* Try if delta is a multiple of step. */
6918 }
6920 /* Only fold here if we can verify we do not overflow one
6921 dimension of a multi-dimensional array. */
6923 {
6924 tree tmp;
6940 }
6943 }
6944 else
6949 }
6951 /* We found the suitable array reference. So copy everything up to it,
6952 and replace the index. */
6959 {
6963 }
6971 }
6974 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6975 means A >= Y && A != MAX, but in this case we know that
6976 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6978 static tree
6980 {
6987 else
6996 {
6999 }
7001 {
7004 }
7005 else
7016 }
7018 /* Fold a sum or difference of at least one multiplication.
7019 Returns the folded tree or NULL if no simplification could be made. */
7021 static tree
7023 {
7027 /* (A * C) +- (B * C) -> (A+-B) * C.
7028 (A * C) +- A -> A * (C+-1).
7029 We are most concerned about the case where C is a constant,
7030 but other combinations show up during loop reduction. Since
7031 it is not difficult, try all four possibilities. */
7034 {
7037 }
7038 else
7039 {
7042 }
7044 {
7047 }
7048 else
7049 {
7052 }
7064 /* No identical multiplicands; see if we can find a common
7065 power-of-two factor in non-power-of-two multiplies. This
7066 can help in multi-dimensional array access. */
7069 {
7072 tree maybe_same;
7076 /* Move min of absolute values to int11. */
7079 {
7084 }
7085 else
7089 {
7097 }
7098 }
7108 }
7110 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7111 specified by EXPR into the buffer PTR of length LEN bytes.
7112 Return the number of bytes placed in the buffer, or zero
7113 upon failure. */
7115 static int
7117 {
7128 {
7132 else
7137 {
7144 else
7146 }
7147 else
7150 }
7152 }
7155 /* Subroutine of native_encode_expr. Encode the REAL_CST
7156 specified by EXPR into the buffer PTR of length LEN bytes.
7157 Return the number of bytes placed in the buffer, or zero
7158 upon failure. */
7160 static int
7162 {
7168 /* There are always 32 bits in each long, no matter the size of
7169 the hosts long. We handle floating point representations with
7170 up to 192 bits. */
7180 {
7185 {
7192 else
7194 }
7195 else
7198 }
7200 }
7202 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7203 specified by EXPR into the buffer PTR of length LEN bytes.
7204 Return the number of bytes placed in the buffer, or zero
7205 upon failure. */
7207 static int
7209 {
7211 tree part;
7222 }
7225 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7226 specified by EXPR into the buffer PTR of length LEN bytes.
7227 Return the number of bytes placed in the buffer, or zero
7228 upon failure. */
7230 static int
7232 {
7242 {
7244 {
7247 }
7248 else
7252 {
7255 }
7256 else
7257 {
7261 }
7263 }
7265 }
7268 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7269 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7270 buffer PTR of length LEN bytes. Return the number of bytes
7271 placed in the buffer, or zero upon failure. */
7273 static int
7275 {
7277 {
7292 }
7293 }
7296 /* Subroutine of native_interpret_expr. Interpret the contents of
7297 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7298 If the buffer cannot be interpreted, return NULL_TREE. */
7300 static tree
7302 {
7316 {
7319 {
7326 else
7328 }
7329 else
7335 else
7338 }
7341 }
7344 /* Subroutine of native_interpret_expr. Interpret the contents of
7345 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7346 If the buffer cannot be interpreted, return NULL_TREE. */
7348 static tree
7350 {
7355 /* There are always 32 bits in each long, no matter the size of
7356 the hosts long. We handle floating point representations with
7357 up to 192 bits. */
7358 REAL_VALUE_TYPE r;
7368 {
7371 {
7378 else
7380 }
7381 else
7386 }
7390 }
7393 /* Subroutine of native_interpret_expr. Interpret the contents of
7394 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7395 If the buffer cannot be interpreted, return NULL_TREE. */
7397 static tree
7399 {
7414 }
7417 /* Subroutine of native_interpret_expr. Interpret the contents of
7418 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7419 If the buffer cannot be interpreted, return NULL_TREE. */
7421 static tree
7423 {
7435 {
7440 }
7442 }
7445 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7446 the buffer PTR of length LEN as a constant of type TYPE. For
7447 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7448 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7449 return NULL_TREE. */
7451 static tree
7453 {
7455 {
7472 }
7473 }
7476 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7477 TYPE at compile-time. If we're unable to perform the conversion
7478 return NULL_TREE. */
7480 static tree
7482 {
7483 /* We support up to 512-bit values (for V8DFmode). */
7487 /* Check that the host and target are sane. */
7496 }
7499 /* Fold a unary expression of code CODE and type TYPE with operand
7500 OP0. Return the folded expression if folding is successful.
7501 Otherwise, return NULL_TREE. */
7503 tree
7505 {
7506 tree tem;
7507 tree arg0;
7515 {
7518 {
7519 /* Don't use STRIP_NOPS, because signedness of argument type
7520 matters. */
7522 }
7523 else
7524 {
7525 /* Strip any conversions that don't change the mode. This
7526 is safe for every expression, except for a comparison
7527 expression because its signedness is derived from its
7528 operands.
7530 Note that this is done as an internal manipulation within
7531 the constant folder, in order to find the simplest
7532 representation of the arguments so that their form can be
7533 studied. In any cases, the appropriate type conversions
7534 should be put back in the tree that will get out of the
7535 constant folder. */
7537 }
7538 }
7541 {
7546 {
7556 /* If this was a conversion, and all we did was to move into
7557 inside the COND_EXPR, bring it back out. But leave it if
7558 it is a conversion from integer to integer and the
7559 result precision is no wider than a word since such a
7560 conversion is cheap and may be optimized away by combine,
7561 while it couldn't if it were outside the COND_EXPR. Then return
7562 so we don't get into an infinite recursion loop taking the
7563 conversion out and then back in. */
7575 && (INTEGRAL_TYPE_P
7587 }
7589 {
7591 {
7595 }
7599 integer_one_node),
7601 integer_zero_node));
7602 }
7603 }
7606 {
7614 /* If we have (type) (a CMP b) and type is an integral type, return
7615 new expression involving the new type. */
7620 /* Handle cases of two conversions in a row. */
7623 {
7645 /* In addition to the cases of two conversions in a row
7646 handled below, if we are converting something to its own
7647 type via an object of identical or wider precision, neither
7648 conversion is needed. */
7655 /* Likewise, if the intermediate and final types are either both
7656 float or both integer, we don't need the middle conversion if
7657 it is wider than the final type and doesn't change the signedness
7658 (for integers). Avoid this if the final type is a pointer
7659 since then we sometimes need the inner conversion. Likewise if
7660 the outer has a precision not equal to the size of its mode. */
7669 && ! final_ptr
7673 /* If we have a sign-extension of a zero-extended value, we can
7674 replace that by a single zero-extension. */
7680 /* Two conversions in a row are not needed unless:
7681 - some conversion is floating-point (overstrict for now), or
7682 - some conversion is a vector (overstrict for now), or
7683 - the intermediate type is narrower than both initial and
7684 final, or
7685 - the intermediate type and innermost type differ in signedness,
7686 and the outermost type is wider than the intermediate, or
7687 - the initial type is a pointer type and the precisions of the
7688 intermediate and final types differ, or
7689 - the final type is a pointer type and the precisions of the
7690 initial and intermediate types differ.
7691 - the final type is a pointer type and the initial type not
7692 - the initial type is a pointer to an array and the final type
7693 not. */
7707 && ! (inside_ptr
7711 }
7713 /* Handle (T *)&A.B.C for A being of type T and B and C
7714 living at offset zero. This occurs frequently in
7715 C++ upcasting and then accessing the base. */
7719 {
7721 tree offset;
7727 /* If the reference was to a (constant) zero offset, we can use
7728 the address of the base if it has the same base type
7729 as the result type. */
7734 }
7739 /* Detect assigning a bitfield. */
7741 && DECL_BIT_FIELD
7743 {
7744 /* Don't leave an assignment inside a conversion
7745 unless assigning a bitfield. */
7747 /* First do the assignment, then return converted constant. */
7752 }
7754 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7755 constants (if x has signed type, the sign bit cannot be set
7756 in c). This folds extension into the BIT_AND_EXPR. */
7761 {
7771 <= HOST_BITS_PER_WIDE_INT
7773 {
7780 #ifdef LOAD_EXTEND_OP
7782 && !flag_syntax_only
7785 {
7789 }
7790 #endif
7791 }
7793 {
7799 }
7800 }
7802 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
7803 T2 being pointers to types of the same size. */
7808 {
7820 }
7822 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7823 of the same precision, and X is a integer type not narrower than
7824 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7831 {
7836 }
7859 /* Convert fabs((double)float) into (double)fabsf(float). */
7862 {
7867 targ0));
7868 }
7869 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7875 /* Strip sign ops from argument. */
7877 {
7881 }
7888 {
7893 }
7895 {
7900 }
7910 /* Convert ~ (-A) to A - 1. */
7914 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7921 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7938 /* The argument to invert_truthvalue must have Boolean type. */
7942 /* Note that the operand of this must be an int
7943 and its values must be 0 or 1.
7944 ("true" is a fixed value perhaps depending on the language,
7945 but we don't handle values other than 1 correctly yet.) */
7960 {
7968 }
7970 {
7974 }
7976 {
7980 {
7989 }
7990 }
8002 {
8010 }
8012 {
8016 }
8018 {
8022 {
8031 }
8032 }
8038 }
8040 /* Fold a binary expression of code CODE and type TYPE with operands
8041 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8042 Return the folded expression if folding is successful. Otherwise,
8043 return NULL_TREE. */
8045 static tree
8047 {
8054 else
8057 /* MIN (MAX (a, b), b) == b. */
8062 /* MIN (MAX (b, a), b) == b. */
8068 /* MIN (a, MAX (a, b)) == a. */
8074 /* MIN (a, MAX (b, a)) == a. */
8081 }
8083 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8084 by changing CODE to reduce the magnitude of constants involved in
8085 ARG0 of the comparison.
8086 Returns a canonicalized comparison tree if a simplification was
8087 possible, otherwise returns NULL_TREE.
8088 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8089 valid if signed overflow is undefined. */
8091 static tree
8095 {
8101 /* Match A +- CST code arg1 and CST code arg1. */
8108 /* Identify the constant in arg0 and its sign. */
8111 else
8115 /* Overflowed constants and zero will cause problems. */
8120 /* See if we can reduce the magnitude of the constant in
8121 arg0 by changing the comparison code. */
8123 {
8124 /* CST <= arg1 -> CST-1 < arg1. */
8127 /* -CST < arg1 -> -CST-1 <= arg1. */
8130 /* CST > arg1 -> CST-1 >= arg1. */
8133 /* -CST >= arg1 -> -CST-1 > arg1. */
8136 else
8138 /* arg1 code' CST' might be more canonical. */
8140 }
8141 else
8142 {
8143 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8147 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8151 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8155 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8159 else
8162 }
8164 /* Now build the constant reduced in magnitude. */
8170 /* If swapping might yield to a more canonical form, do so. */
8173 else
8175 }
8177 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8178 overflow further. Try to decrease the magnitude of constants involved
8179 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8180 and put sole constants at the second argument position.
8181 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8183 static tree
8186 {
8187 tree t;
8192 /* In principle pointers also have undefined overflow behavior,
8193 but that causes problems elsewhere. */
8198 /* Try canonicalization by simplifying arg0. */
8203 {
8207 }
8209 /* Try canonicalization by simplifying arg1 using the swapped
8210 comparison. */
8218 }
8220 /* Subroutine of fold_binary. This routine performs all of the
8221 transformations that are common to the equality/inequality
8222 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8223 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8224 fold_binary should call fold_binary. Fold a comparison with
8225 tree code CODE and type TYPE with operands OP0 and OP1. Return
8226 the folded comparison or NULL_TREE. */
8228 static tree
8230 {
8243 /* If one arg is a real or integer constant, put it last. */
8247 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8254 {
8258 tree lhs;
8265 /* If the constant operation overflowed this can be
8266 simplified as a comparison against INT_MAX/INT_MIN. */
8269 {
8273 /* Get the sign of the constant on the lhs if the
8274 operation were VARIABLE + CONST1. */
8278 /* The sign of the constant determines if we overflowed
8279 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8280 Canonicalize to the INT_MIN overflow by swapping the comparison
8281 if necessary. */
8285 /* We now can look at the canonicalized case
8286 VARIABLE + 1 CODE2 INT_MIN
8287 and decide on the result. */
8296 }
8301 {
8303 "when changing X +- C1 cmp C2 to "
8305 WARN_STRICT_OVERFLOW_COMPARISON);
8307 }
8308 }
8310 /* For comparisons of pointers we can decompose it to a compile time
8311 comparison of the base objects and the offsets into the object.
8312 This requires at least one operand being an ADDR_EXPR to do more
8313 than the operand_equal_p test below. */
8317 {
8324 /* Get base and offset for the access. Strip ADDR_EXPR for
8325 get_inner_reference, but put it back by stripping INDIRECT_REF
8326 off the base object if possible. */
8329 {
8335 else
8337 }
8341 {
8345 /* We have to make sure to have an indirect/non-indirect base1
8346 just the same as we did for base0. */
8352 }
8356 /* If we have equivalent bases we might be able to simplify. */
8359 {
8360 /* We can fold this expression to a constant if the non-constant
8361 offset parts are equal. */
8365 {
8367 {
8381 }
8382 }
8383 /* We can simplify the comparison to a comparison of the variable
8384 offset parts if the constant offset parts are equal.
8385 Be careful to use signed size type here because otherwise we
8386 mess with array offsets in the wrong way. This is possible
8387 because pointer arithmetic is restricted to retain within an
8388 object and overflow on pointer differences is undefined as of
8389 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8391 {
8392 tree signed_size_type_node;
8395 /* By converting to signed size type we cover middle-end pointer
8396 arithmetic which operates on unsigned pointer types of size
8397 type size and ARRAY_REF offsets which are properly sign or
8398 zero extended from their type in case it is narrower than
8399 size type. */
8402 else
8406 else
8410 }
8411 }
8412 }
8414 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8415 same object, then we can fold this to a comparison of the two offsets in
8416 signed size type. This is possible because pointer arithmetic is
8417 restricted to retain within an object and overflow on pointer differences
8418 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8420 We check flag_wrapv directly because pointers types are unsigned,
8421 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8422 normally what we want to avoid certain odd overflow cases, but
8423 not here. */
8425 && !flag_wrapv
8427 {
8433 {
8434 tree signed_size_type_node;
8437 /* By converting to signed size type we cover middle-end pointer
8438 arithmetic which operates on unsigned pointer types of size
8439 type size and ARRAY_REF offsets which are properly sign or
8440 zero extended from their type in case it is narrower than
8441 size type. */
8444 else
8448 else
8452 }
8453 }
8455 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8456 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8457 the resulting offset is smaller in absolute value than the
8458 original one. */
8466 {
8471 tree cst;
8473 "occur when combining constants around "
8476 /* Put the constant on the side where it doesn't overflow and is
8477 of lower absolute value than before. */
8483 {
8486 variable1,
8489 }
8496 {
8501 variable2);
8502 }
8503 }
8505 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8506 signed arithmetic case. That form is created by the compiler
8507 often enough for folding it to be of value. One example is in
8508 computing loop trip counts after Operator Strength Reduction. */
8514 {
8523 "eliminating multiplication in comparison "
8525 WARN_STRICT_OVERFLOW_COMPARISON);
8527 /* If const1 is negative we swap the sense of the comparison. */
8532 }
8539 {
8547 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8552 /* (-a) CMP (-b) -> b CMP a */
8559 {
8560 REAL_VALUE_TYPE cst;
8563 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8570 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8571 /* a CMP (-0) -> a CMP 0 */
8576 /* x != NaN is always true, other ops are always false. */
8579 {
8582 }
8584 /* Fold comparisons against infinity. */
8586 {
8590 }
8591 }
8593 /* If this is a comparison of a real constant with a PLUS_EXPR
8594 or a MINUS_EXPR of a real constant, we can convert it into a
8595 comparison with a revised real constant as long as no overflow
8596 occurs when unsafe_math_optimizations are enabled. */
8608 /* Likewise, we can simplify a comparison of a real constant with
8609 a MINUS_EXPR whose first operand is also a real constant, i.e.
8610 (c1 - x) < c2 becomes x > c1-c2. */
8621 /* Fold comparisons against built-in math functions. */
8623 && flag_unsafe_math_optimizations
8625 {
8629 {
8633 }
8634 }
8635 }
8637 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
8641 /* This optimization is invalid for ordered comparisons
8642 if CONST+INCR overflows or if foo+incr might overflow.
8643 This optimization is invalid for floating point due to rounding.
8644 For pointer types we assume overflow doesn't happen. */
8648 {
8652 {
8658 }
8659 else
8660 {
8666 }
8669 /* If VAROP is a reference to a bitfield, we must mask
8670 the constant by the width of the field. */
8675 {
8680 /* First check whether the comparison would come out
8681 always the same. If we don't do that we would
8682 change the meaning with the masking. */
8695 }
8698 }
8703 {
8704 /* If we are widening one operand of an integer comparison,
8705 see if the other operand is similarly being widened. Perhaps we
8706 can do the comparison in the narrower type. */
8711 /* Or if we are changing signedness. */
8715 }
8717 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8718 constant, we can simplify it. */
8723 {
8727 }
8729 /* Simplify comparison of something with itself. (For IEEE
8730 floating-point, we can only do some of these simplifications.) */
8732 {
8734 {
8749 /* For NE, we can only do this simplification if integer
8750 or we don't honor IEEE floating point NaNs. */
8754 /* ... fall through ... */
8760 }
8761 }
8763 /* If we are comparing an expression that just has comparisons
8764 of two integer values, arithmetic expressions of those comparisons,
8765 and constants, we can simplify it. There are only three cases
8766 to check: the two values can either be equal, the first can be
8767 greater, or the second can be greater. Fold the expression for
8768 those three values. Since each value must be 0 or 1, we have
8769 eight possibilities, each of which corresponds to the constant 0
8770 or 1 or one of the six possible comparisons.
8772 This handles common cases like (a > b) == 0 but also handles
8773 expressions like ((x > y) - (y > x)) > 0, which supposedly
8774 occur in macroized code. */
8777 {
8782 /* Don't handle degenerate cases here; they should already
8783 have been handled anyway. */
8792 {
8796 /* We can't just pass T to eval_subst in case cval1 or cval2
8797 was the same as ARG1. */
8799 tree high_result
8803 arg1);
8804 tree equal_result
8808 arg1);
8809 tree low_result
8813 arg1);
8815 /* All three of these results should be 0 or 1. Confirm they are.
8816 Then use those values to select the proper code to use. */
8821 {
8822 /* Make a 3-bit mask with the high-order bit being the
8823 value for `>', the next for '=', and the low for '<'. */
8827 {
8829 /* Always false. */
8850 /* Always true. */
8852 }
8857 }
8858 }
8859 }
8861 /* Fold a comparison of the address of COMPONENT_REFs with the same
8862 type and component to a comparison of the address of the base
8863 object. In short, &x->a OP &y->a to x OP y and
8864 &x->a OP &y.a to x OP &y */
8869 {
8873 {
8879 }
8880 }
8882 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8883 into a single range test. */
8891 {
8895 }
8897 /* Fold ~X op ~Y as Y op X. */
8900 {
8905 }
8907 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
8910 {
8916 }
8919 }
8922 /* Subroutine of fold_binary. Optimize complex multiplications of the
8923 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8924 argument EXPR represents the expression "z" of type TYPE. */
8926 static tree
8928 {
8933 {
8936 }
8938 {
8941 }
8942 else
8943 {
8947 }
8956 }
8959 /* Fold a binary expression of code CODE and type TYPE with operands
8960 OP0 and OP1. Return the folded expression if folding is
8961 successful. Otherwise, return NULL_TREE. */
8963 tree
8965 {
8980 /* Strip any conversions that don't change the mode. This is
8981 safe for every expression, except for a comparison expression
8982 because its signedness is derived from its operands. So, in
8983 the latter case, only strip conversions that don't change the
8984 signedness.
8986 Note that this is done as an internal manipulation within the
8987 constant folder, in order to find the simplest representation
8988 of the arguments so that their form can be studied. In any
8989 cases, the appropriate type conversions should be put back in
8990 the tree that will get out of the constant folder. */
8993 {
8996 }
8997 else
8998 {
9001 }
9003 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9004 constant but we can't do arithmetic on them. */
9009 {
9014 else
9018 {
9022 }
9023 }
9025 /* If this is a commutative operation, and ARG0 is a constant, move it
9026 to ARG1 to reduce the number of tests below. */
9031 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9033 First check for cases where an arithmetic operation is applied to a
9034 compound, conditional, or comparison operation. Push the arithmetic
9035 operation inside the compound or conditional to see if any folding
9036 can then be done. Convert comparison to conditional for this purpose.
9037 The also optimizes non-constant cases that used to be done in
9038 expand_expr.
9040 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9041 one of the operands is a comparison and the other is a comparison, a
9042 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9043 code below would make the expression more complex. Change it to a
9044 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9045 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9057 {
9061 boolean_type_node,
9069 }
9073 {
9085 {
9091 }
9094 {
9100 }
9101 }
9104 {
9106 /* A + (-B) -> A - B */
9111 /* (-A) + B -> B - A */
9117 /* Convert ~A + 1 to -A. */
9123 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9124 same or one. */
9128 {
9132 }
9135 {
9139 /* ~X + X is -1. */
9143 {
9146 }
9148 /* X + ~X is -1. */
9152 {
9155 }
9157 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9158 with a constant, and the two constants have no bits in common,
9159 we should treat this as a BIT_IOR_EXPR since this may produce more
9160 simplifications. */
9168 {
9171 }
9173 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9174 (plus (plus (mult) (mult)) (foo)) so that we can
9175 take advantage of the factoring cases below. */
9182 {
9188 else
9210 parg1)));
9211 }
9213 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
9214 of the array. Loop optimizer sometimes produce this type of
9215 expressions. */
9217 {
9221 }
9223 {
9227 }
9228 }
9229 else
9230 {
9231 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9235 /* Likewise if the operands are reversed. */
9239 /* Convert X + -C into X - C. */
9242 {
9248 }
9250 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9251 to __complex__ ( x, y ). This is not the same for SNaNs or
9252 if signed zeros are involved. */
9256 {
9263 {
9267 {
9273 }
9275 {
9281 }
9282 }
9283 }
9291 /* Convert x+x into x*2.0. */
9297 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
9301 {
9306 {
9307 tree tree0;
9310 }
9311 }
9312 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
9316 {
9321 {
9322 tree tree0;
9325 }
9326 }
9327 }
9329 bit_rotate:
9330 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9331 is a rotate of A by C1 bits. */
9332 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9333 is a rotate of A by B bits. */
9334 {
9343 {
9362 {
9370 TYPE_PRECISION
9375 ? LROTATE_EXPR
9378 }
9380 {
9388 TYPE_PRECISION
9393 ? LROTATE_EXPR
9396 }
9397 }
9398 }
9400 associate:
9401 /* In most languages, can't associate operations on floats through
9402 parentheses. Rather than remember where the parentheses were, we
9403 don't associate floats at all, unless the user has specified
9404 -funsafe-math-optimizations. */
9407 {
9412 /* Split both trees into variables, constants, and literals. Then
9413 associate each group together, the constants with literals,
9414 then the result with variables. This increases the chances of
9415 literals being recombined later and of generating relocatable
9416 expressions for the sum of a constant and literal. */
9421 /* With undefined overflow we can only associate constants
9422 with one variable. */
9426 {
9434 /* The only case we can still associate with two variables
9435 is if they are the same, modulo negation. */
9438 }
9440 /* Only do something if we found more than two objects. Otherwise,
9441 nothing has changed and we risk infinite recursion. */
9447 {
9448 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9457 /* Preserve the MINUS_EXPR if the negative part of the literal is
9458 greater than the positive part. Otherwise, the multiplicative
9459 folding code (i.e extract_muldiv) may be fooled in case
9460 unsigned constants are subtracted, like in the following
9461 example: ((X*2 + 4) - 8U)/2. */
9463 {
9467 {
9471 }
9472 else
9473 {
9477 }
9478 }
9480 {
9485 else
9486 {
9492 }
9493 }
9498 }
9499 }
9504 /* A - (-B) -> A + B */
9507 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9515 /* Convert -A - 1 to ~A. */
9523 /* Convert -1 - A to ~A. */
9529 {
9535 /* Fold A - (A & B) into ~B & A. */
9538 {
9543 arg0);
9548 arg0);
9549 }
9551 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9552 any power of 2 minus 1. */
9557 {
9563 {
9567 }
9568 }
9569 }
9571 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9575 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9576 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9577 (-ARG1 + ARG0) reduces to -ARG1. */
9581 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9582 __complex__ ( x, -y ). This is not the same for SNaNs or if
9583 signed zeros are involved. */
9587 {
9594 {
9598 {
9600 arg1r ? arg1r
9605 }
9607 {
9611 arg1i ? arg1i
9614 }
9615 }
9616 }
9618 /* Fold &x - &x. This can happen from &x.foo - &x.
9619 This is unsafe for certain floats even in non-IEEE formats.
9620 In IEEE, it is unsafe because it does wrong for NaNs.
9621 Also note that operand_equal_p is always false if an operand
9622 is volatile. */
9628 /* A - B -> A + (-B) if B is easily negatable. */
9631 /* Avoid this transformation if B is a positive REAL_CST. */
9639 /* Try folding difference of addresses. */
9640 {
9641 HOST_WIDE_INT diff;
9647 }
9649 /* Fold &a[i] - &a[j] to i-j. */
9654 {
9659 {
9667 }
9668 }
9670 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9671 of the array. Loop optimizer sometimes produce this type of
9672 expressions. */
9674 {
9678 }
9686 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9687 same or one. */
9691 {
9695 }
9700 /* (-A) * (-B) -> A * B */
9711 {
9716 /* Transform x * -1 into -x. */
9719 /* Transform x * -C into -x * C if x is easily negatable. */
9728 /* (a * (1 << b)) is (a << b) */
9744 {
9747 "occur when simplifying "
9749 WARN_STRICT_OVERFLOW_MISC);
9751 }
9753 /* Optimize z * conj(z) for integer complex numbers. */
9760 }
9761 else
9762 {
9763 /* Maybe fold x * 0 to 0. The expressions aren't the same
9764 when x is NaN, since x * 0 is also NaN. Nor are they the
9765 same in modes with signed zeros, since multiplying a
9766 negative value by 0 gives -0, not +0. */
9771 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9776 /* Transform x * -1.0 into -x. */
9781 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9786 {
9792 }
9794 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9796 {
9799 {
9802 }
9803 }
9805 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9806 This is not the same for NaNs or if signed zeros are
9807 involved. */
9813 {
9825 }
9827 /* Optimize z * conj(z) for floating point complex numbers.
9828 Guarded by flag_unsafe_math_optimizations as non-finite
9829 imaginary components don't produce scalar results. */
9840 {
9844 /* Optimizations of root(...)*root(...). */
9846 {
9851 /* Optimize sqrt(x)*sqrt(x) as x. */
9857 /* Optimize root(x)*root(y) as root(x*y). */
9861 }
9863 /* Optimize expN(x)*expN(y) as expN(x+y). */
9865 {
9871 }
9873 /* Optimizations of pow(...)*pow(...). */
9877 {
9883 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9885 {
9889 }
9891 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9893 {
9897 }
9898 }
9900 /* Optimize tan(x)*cos(x) as sin(x). */
9909 {
9914 }
9916 /* Optimize x*pow(x,c) as pow(x,c+1). */
9920 {
9926 {
9928 REAL_VALUE_TYPE c;
9929 tree arg;
9935 }
9936 }
9938 /* Optimize pow(x,c)*x as pow(x,c+1). */
9942 {
9948 {
9950 REAL_VALUE_TYPE c;
9951 tree arg;
9957 }
9958 }
9960 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9963 {
9967 {
9970 }
9971 }
9972 }
9973 }
9977 bit_ior:
9985 /* ~X | X is -1. */
9988 {
9991 }
9993 /* X | ~X is -1. */
9996 {
9999 }
10001 /* Canonicalize (X & C1) | C2. */
10005 {
10013 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10018 {
10022 }
10023 else
10024 {
10028 }
10030 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10035 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
10045 arg1);
10046 }
10048 /* (X & Y) | Y is (X, Y). */
10052 /* (X & Y) | X is (Y, X). */
10057 /* X | (X & Y) is (Y, X). */
10062 /* X | (Y & X) is (Y, X). */
10072 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10074 This results in more efficient code for machines without a NAND
10075 instruction. Combine will canonicalize to the first form
10076 which will allow use of NAND instructions provided by the
10077 backend if they exist. */
10080 {
10085 }
10087 /* See if this can be simplified into a rotate first. If that
10088 is unsuccessful continue in the association code. */
10099 /* ~X ^ X is -1. */
10102 {
10105 }
10107 /* X ^ ~X is -1. */
10110 {
10113 }
10115 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10116 with a constant, and the two constants have no bits in common,
10117 we should treat this as a BIT_IOR_EXPR since this may produce more
10118 simplifications. */
10126 {
10129 }
10131 /* (X | Y) ^ X -> Y & ~ X*/
10134 {
10137 arg1);
10141 }
10143 /* (Y | X) ^ X -> Y & ~ X*/
10146 {
10149 arg1);
10153 }
10155 /* X ^ (X | Y) -> Y & ~ X*/
10158 {
10161 arg0);
10165 }
10167 /* X ^ (Y | X) -> Y & ~ X*/
10170 {
10173 arg0);
10177 }
10179 /* Convert ~X ^ ~Y to X ^ Y. */
10186 /* Convert ~X ^ C to X ^ ~C. */
10193 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10200 /* Fold (X & Y) ^ Y as ~X & Y. */
10203 {
10208 }
10209 /* Fold (X & Y) ^ X as ~Y & X. */
10213 {
10218 }
10219 /* Fold X ^ (X & Y) as X & ~Y. */
10222 {
10227 }
10228 /* Fold X ^ (Y & X) as ~Y & X. */
10232 {
10237 }
10239 /* See if this can be simplified into a rotate first. If that
10240 is unsuccessful continue in the association code. */
10251 /* ~X & X is always zero. */
10256 /* X & ~X is always zero. */
10261 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10271 /* (X | Y) & Y is (X, Y). */
10275 /* (X | Y) & X is (Y, X). */
10280 /* X & (X | Y) is (Y, X). */
10285 /* X & (Y | X) is (Y, X). */
10291 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10295 {
10301 }
10302 /* Fold ~X & 1 as (X & 1) == 0. */
10305 {
10311 }
10313 /* Fold (X ^ Y) & Y as ~X & Y. */
10316 {
10321 }
10322 /* Fold (X ^ Y) & X as ~Y & X. */
10326 {
10331 }
10332 /* Fold X & (X ^ Y) as X & ~Y. */
10335 {
10340 }
10341 /* Fold X & (Y ^ X) as ~Y & X. */
10345 {
10350 }
10355 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10358 {
10359 unsigned int prec
10366 }
10368 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10370 This results in more efficient code for machines without a NOR
10371 instruction. Combine will canonicalize to the first form
10372 which will allow use of NOR instructions provided by the
10373 backend if they exist. */
10376 {
10381 }
10386 /* Don't touch a floating-point divide by zero unless the mode
10387 of the constant can represent infinity. */
10393 /* Optimize A / A to 1.0 if we don't care about
10394 NaNs or Infinities. Skip the transformation
10395 for non-real operands. */
10400 {
10404 }
10406 /* The complex version of the above A / A optimization. */
10409 {
10413 {
10415 /* omit_two_operands will call fold_convert for us. */
10417 }
10418 }
10420 /* (-A) / (-B) -> A / B */
10430 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
10435 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
10440 /* If ARG1 is a constant, we can convert this to a multiply by the
10441 reciprocal. This does not have the same rounding properties,
10442 so only do this if -funsafe-math-optimizations. We can actually
10443 always safely do it if ARG1 is a power of two, but it's hard to
10444 tell if it is or not in a portable manner. */
10446 {
10451 /* Find the reciprocal if optimizing and the result is exact. */
10453 {
10454 REAL_VALUE_TYPE r;
10457 {
10461 }
10462 }
10463 }
10464 /* Convert A/B/C to A/(B*C). */
10471 /* Convert A/(B/C) to (A/B)*C. */
10479 /* Convert C1/(X*C2) into (C1/C2)/X. */
10484 {
10490 }
10493 {
10497 /* Optimize sin(x)/cos(x) as tan(x). */
10503 {
10508 }
10510 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10516 {
10520 {
10524 }
10525 }
10527 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10528 NaNs or Infinities. */
10532 {
10539 {
10544 }
10545 }
10547 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10548 NaNs or Infinities. */
10552 {
10559 {
10563 {
10567 tmp);
10568 }
10569 }
10570 }
10572 /* Optimize pow(x,c)/x as pow(x,c-1). */
10576 {
10582 {
10584 REAL_VALUE_TYPE c;
10585 tree arg;
10591 }
10592 }
10594 /* Optimize x/expN(y) into x*expN(-y). */
10596 {
10601 }
10603 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10607 {
10614 }
10615 }
10620 /* Simplify A / (B << N) where A and B are positive and B is
10621 a power of 2, to A >> (N + log2(B)). */
10626 {
10629 {
10636 WARN_STRICT_OVERFLOW_MISC);
10642 }
10643 }
10644 /* Fall thru */
10653 /* X / -1 is -X. */
10660 /* Convert -A / -B to A / B when the type is signed and overflow is
10661 undefined. */
10665 {
10668 "when distributing negation across "
10670 WARN_STRICT_OVERFLOW_MISC);
10673 }
10677 {
10680 "when distributing negation across "
10682 WARN_STRICT_OVERFLOW_MISC);
10685 }
10687 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10688 operation, EXACT_DIV_EXPR.
10690 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10691 At one time others generated faster code, it's not clear if they do
10692 after the last round to changes to the DIV code in expmed.c. */
10701 {
10705 WARN_STRICT_OVERFLOW_MISC);
10707 }
10715 /* X % 1 is always zero, but be sure to preserve any side
10716 effects in X. */
10720 /* X % 0, return X % 0 unchanged so that we can get the
10721 proper warnings and errors. */
10725 /* 0 % X is always zero, but be sure to preserve any side
10726 effects in X. Place this after checking for X == 0. */
10730 /* X % -1 is zero. */
10737 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10738 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10743 {
10745 /* Also optimize A % (C << N) where C is a power of 2,
10746 to A & ((C << N) - 1). */
10751 {
10756 "occur when simplifying "
10758 WARN_STRICT_OVERFLOW_MISC);
10762 }
10763 }
10765 /* X % -C is the same as X % C. */
10772 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10777 /* X % -Y is the same as X % Y. */
10788 {
10792 WARN_STRICT_OVERFLOW_MISC);
10794 }
10805 /* Optimize -1 >> x for arithmetic right shifts. */
10808 /* ... fall through ... */
10811 shift:
10817 /* Since negative shift count is not well-defined,
10818 don't try to compute it in the compiler. */
10822 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10827 {
10831 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10832 being well defined. */
10834 {
10839 else
10841 }
10845 }
10847 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10848 into x & ((unsigned)-1 >> c) for unsigned types. */
10856 {
10859 tree lshift;
10860 tree arg00;
10863 {
10870 }
10871 }
10873 /* Rewrite an LROTATE_EXPR by a constant into an
10874 RROTATE_EXPR by a new constant. */
10876 {
10881 }
10883 /* If we have a rotate of a bit operation with the rotate count and
10884 the second operand of the bit operation both constant,
10885 permute the two operations. */
10897 /* Two consecutive rotates adding up to the width of the mode can
10898 be ignored. */
10935 /* Note that the operands of this must be ints
10936 and their values must be 0 or 1.
10937 ("true" is a fixed value perhaps depending on the language.) */
10938 /* If first arg is constant zero, return it. */
10942 /* If either arg is constant true, drop it. */
10946 /* Preserve sequence points. */
10949 /* If second arg is constant zero, result is zero, but first arg
10950 must be evaluated. */
10953 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10954 case will be handled here. */
10958 /* !X && X is always false. */
10962 /* X && !X is always false. */
10967 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10968 means A >= Y && A != MAX, but in this case we know that
10969 A < X <= MAX. */
10973 {
10981 }
10983 truth_andor:
10984 /* We only do these simplifications if we are optimizing. */
10988 /* Check for things like (A || B) && (A || C). We can convert this
10989 to A || (B && C). Note that either operator can be any of the four
10990 truth and/or operations and the transformation will still be
10991 valid. Also note that we only care about order for the
10992 ANDIF and ORIF operators. If B contains side effects, this
10993 might change the truth-value of A. */
11000 {
11020 /* This case if tricky because we must either have commutative
11021 operators or else A10 must not have side-effects. */
11027 a01);
11028 }
11030 /* See if we can build a range comparison. */
11034 /* Check for the possibility of merging component references. If our
11035 lhs is another similar operation, try to merge its rhs with our
11036 rhs. Then try to merge our lhs and rhs. */
11048 /* Note that the operands of this must be ints
11049 and their values must be 0 or true.
11050 ("true" is a fixed value perhaps depending on the language.) */
11051 /* If first arg is constant true, return it. */
11055 /* If either arg is constant zero, drop it. */
11059 /* Preserve sequence points. */
11062 /* If second arg is constant true, result is true, but we must
11063 evaluate first arg. */
11066 /* Likewise for first arg, but note this only occurs here for
11067 TRUTH_OR_EXPR. */
11071 /* !X || X is always true. */
11075 /* X || !X is always true. */
11083 /* If the second arg is constant zero, drop it. */
11086 /* If the second arg is constant true, this is a logical inversion. */
11088 {
11089 /* Only call invert_truthvalue if operand is a truth value. */
11092 else
11095 }
11096 /* Identical arguments cancel to zero. */
11100 /* !X ^ X is always true. */
11105 /* X ^ !X is always true. */
11118 /* bool_var != 0 becomes bool_var. */
11123 /* bool_var == 1 becomes bool_var. */
11128 /* bool_var != 1 becomes !bool_var. */
11133 /* bool_var == 0 becomes !bool_var. */
11138 /* If this is an equality comparison of the address of two non-weak,
11139 unaliased symbols neither of which are extern (since we do not
11140 have access to attributes for externs), then we know the result. */
11153 {
11154 /* We know that we're looking at the address of two
11155 non-weak, unaliased, static _DECL nodes.
11157 It is both wasteful and incorrect to call operand_equal_p
11158 to compare the two ADDR_EXPR nodes. It is wasteful in that
11159 all we need to do is test pointer equality for the arguments
11160 to the two ADDR_EXPR nodes. It is incorrect to use
11161 operand_equal_p as that function is NOT equivalent to a
11162 C equality test. It can in fact return false for two
11163 objects which would test as equal using the C equality
11164 operator. */
11168 type);
11169 }
11171 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
11172 a MINUS_EXPR of a constant, we can convert it into a comparison with
11173 a revised constant as long as no overflow occurs. */
11185 /* Similarly for a NEGATE_EXPR. */
11193 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11202 /* Transform comparisons of the form X +- C CMP X. */
11208 {
11215 else
11218 }
11220 /* If we have X - Y == 0, we can convert that to X == Y and similarly
11221 for !=. Don't do this for ordered comparisons due to overflow. */
11227 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11232 /* If this is an EQ or NE comparison with zero and ARG0 is
11233 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11234 two operations, but the latter can be done in one less insn
11235 on machines that have only two-operand insns or on which a
11236 constant cannot be the first operand. */
11239 {
11244 return
11250 integer_one_node)),
11251 arg1);
11254 return
11260 integer_one_node)),
11261 arg1);
11262 }
11264 /* If this is an NE or EQ comparison of zero against the result of a
11265 signed MOD operation whose second operand is a power of 2, make
11266 the MOD operation unsigned since it is simpler and equivalent. */
11274 {
11284 }
11286 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11287 C1 is a valid shift constant, and C2 is a power of two, i.e.
11288 a single bit. */
11292 == INTEGER_CST
11295 {
11300 /* Check for a valid shift count. */
11303 {
11307 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11308 can be rewritten as (X & (C2 << C1)) != 0. */
11310 {
11314 }
11315 /* Otherwise, for signed (arithmetic) shifts,
11316 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11317 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11321 /* Otherwise, of unsigned (logical) shifts,
11322 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11323 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11324 else
11328 arg000);
11329 }
11330 }
11332 /* If this is an NE comparison of zero with an AND of one, remove the
11333 comparison since the AND will give the correct value. */
11340 /* If we have (A & C) == C where C is a power of 2, convert this into
11341 (A & C) != 0. Similarly for NE_EXPR. */
11347 integer_zero_node));
11349 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11350 bit, then fold the expression into A < 0 or A >= 0. */
11355 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11356 Similarly for NE_EXPR. */
11360 {
11369 }
11371 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11372 Similarly for NE_EXPR. */
11376 {
11383 }
11385 /* If this is a comparison of a field, we may be able to simplify it. */
11388 /* Handle the constant case even without -O
11389 to make sure the warnings are given. */
11391 {
11395 }
11397 /* Optimize comparisons of strlen vs zero to a compare of the
11398 first character of the string vs zero. To wit,
11399 strlen(ptr) == 0 => *ptr == 0
11400 strlen(ptr) != 0 => *ptr != 0
11401 Other cases should reduce to one of these two (or a constant)
11402 due to the return value of strlen being unsigned. */
11405 {
11413 {
11417 }
11418 }
11420 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11421 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11425 {
11432 {
11434 {
11437 }
11440 }
11441 }
11443 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
11449 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
11454 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
11461 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
11469 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11470 (X & C) == 0 when C is a single bit. */
11475 {
11481 }
11483 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11484 constant C is a power of two, i.e. a single bit. */
11491 {
11495 }
11497 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11498 when is C is a power of two, i.e. a single bit. */
11505 {
11511 }
11515 {
11518 }
11520 /* Fold -X op -Y as X op Y, where op is eq/ne. */
11527 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11530 {
11542 arg01),
11550 arg01),
11558 arg00),
11566 arg00),
11568 }
11572 {
11579 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11580 operand_equal_p guarantees no side-effects so we don't need
11581 to use omit_one_operand on Z. */
11591 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11598 arg10);
11599 }
11601 /* Attempt to simplify equality/inequality comparisons of complex
11602 values. Only lower the comparison if the result is known or
11603 can be simplified to a single scalar comparison. */
11608 {
11613 {
11616 }
11617 else
11618 {
11621 }
11624 {
11627 }
11628 else
11629 {
11632 }
11636 {
11638 {
11643 }
11644 else
11645 {
11650 }
11651 }
11655 {
11657 {
11662 }
11663 else
11664 {
11669 }
11670 }
11671 }
11683 /* Transform comparisons of the form X +- C CMP X. */
11690 {
11697 else
11700 /* (X - c) > X becomes false. */
11704 {
11708 "occur when assuming that (X - c) > X "
11710 WARN_STRICT_OVERFLOW_ALL);
11712 }
11714 /* Likewise (X + c) < X becomes false. */
11718 {
11722 "occur when assuming that "
11724 WARN_STRICT_OVERFLOW_ALL);
11726 }
11728 /* Convert (X - c) <= X to true. */
11733 {
11737 "occur when assuming that "
11739 WARN_STRICT_OVERFLOW_ALL);
11741 }
11743 /* Convert (X + c) >= X to true. */
11748 {
11752 "occur when assuming that "
11754 WARN_STRICT_OVERFLOW_ALL);
11756 }
11759 {
11760 /* Convert X + c > X and X - c < X to true for integers. */
11764 {
11767 "not occur when assuming that "
11769 WARN_STRICT_OVERFLOW_ALL);
11771 }
11776 {
11779 "not occur when assuming that "
11781 WARN_STRICT_OVERFLOW_ALL);
11783 }
11785 /* Convert X + c <= X and X - c >= X to false for integers. */
11789 {
11792 "not occur when assuming that "
11794 WARN_STRICT_OVERFLOW_ALL);
11796 }
11801 {
11804 "not occur when assuming that "
11806 WARN_STRICT_OVERFLOW_ALL);
11808 }
11809 }
11810 }
11812 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11813 This transformation affects the cases which are handled in later
11814 optimizations involving comparisons with non-negative constants. */
11818 {
11820 {
11825 }
11827 {
11832 }
11833 }
11835 /* Comparisons with the highest or lowest possible integer of
11836 the specified precision will have known values. */
11837 {
11845 {
11846 HOST_WIDE_INT signed_max_hi;
11851 {
11858 {
11862 }
11863 else
11864 {
11868 }
11869 }
11870 else
11871 {
11880 {
11883 }
11884 else
11885 {
11888 }
11889 }
11894 {
11907 /* The GE_EXPR and LT_EXPR cases above are not normally
11908 reached because of previous transformations. */
11912 }
11914 == max_hi
11917 {
11928 }
11930 == min_hi
11933 {
11948 }
11950 == min_hi
11953 {
11962 }
11967 /* We will flip the signedness of the comparison operator
11968 associated with the mode of arg1, so the sign bit is
11969 specified by this mode. Check that arg1 is the signed
11970 max associated with this sign bit. */
11972 /* signed_type does not work on pointer types. */
11974 {
11975 /* The following case also applies to X < signed_max+1
11976 and X >= signed_max+1 because previous transformations. */
11978 {
11985 }
11986 }
11987 }
11988 }
11990 /* If we are comparing an ABS_EXPR with a constant, we can
11991 convert all the cases into explicit comparisons, but they may
11992 well not be faster than doing the ABS and one comparison.
11993 But ABS (X) <= C is a range comparison, which becomes a subtraction
11994 and a comparison, and is probably faster. */
12008 /* Convert ABS_EXPR<x> >= 0 to true. */
12015 {
12018 "when simplifying comparison of "
12020 WARN_STRICT_OVERFLOW_CONDITIONAL);
12022 }
12024 /* Convert ABS_EXPR<x> < 0 to false. */
12029 {
12032 "when simplifying comparison of "
12034 WARN_STRICT_OVERFLOW_CONDITIONAL);
12036 }
12038 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12039 and similarly for >= into !=. */
12055 return
12074 {
12078 }
12080 /* If the first operand is NaN, the result is constant. */
12084 {
12086 ? integer_zero_node
12089 }
12091 /* If the second operand is NaN, the result is constant. */
12095 {
12097 ? integer_zero_node
12100 }
12102 /* Simplify unordered comparison of something with itself. */
12108 && !flag_trapping_math
12112 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12113 {
12124 }
12129 /* When pedantic, a compound expression can be neither an lvalue
12130 nor an integer constant expression. */
12133 /* Don't let (0, 0) be null pointer constant. */
12147 /* An ASSERT_EXPR should never be passed to fold_binary. */
12153 }
12155 /* Callback for walk_tree, looking for LABEL_EXPR.
12156 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
12157 Do not check the sub-tree of GOTO_EXPR. */
12159 static tree
12163 {
12165 {
12170 /* no break */
12173 }
12174 }
12176 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
12177 accessible from outside the sub-tree. Returns NULL_TREE if no
12178 addressable label is found. */
12180 static bool
12182 {
12184 }
12186 /* Fold a ternary expression of code CODE and type TYPE with operands
12187 OP0, OP1, and OP2. Return the folded expression if folding is
12188 successful. Otherwise, return NULL_TREE. */
12190 tree
12192 {
12193 tree tem;
12200 /* Strip any conversions that don't change the mode. This is safe
12201 for every expression, except for a comparison expression because
12202 its signedness is derived from its operands. So, in the latter
12203 case, only strip conversions that don't change the signedness.
12205 Note that this is done as an internal manipulation within the
12206 constant folder, in order to find the simplest representation of
12207 the arguments so that their form can be studied. In any cases,
12208 the appropriate type conversions should be put back in the tree
12209 that will get out of the constant folder. */
12211 {
12214 }
12217 {
12220 }
12223 {
12227 {
12233 }
12237 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12238 so all simple results must be passed through pedantic_non_lvalue. */
12240 {
12243 /* Only optimize constant conditions when the selected branch
12244 has the same type as the COND_EXPR. This avoids optimizing
12245 away "c ? x : throw", where the throw has a void type.
12246 Avoid throwing away that operand which contains label. */
12253 }
12257 /* If we have A op B ? A : C, we may be able to convert this to a
12258 simpler expression, depending on the operation and the values
12259 of B and C. Signed zeros prevent all of these transformations,
12260 for reasons given above each one.
12262 Also try swapping the arguments and inverting the conditional. */
12267 {
12271 }
12275 op2,
12278 {
12281 {
12285 }
12286 }
12288 /* If the second operand is simpler than the third, swap them
12289 since that produces better jump optimization results. */
12292 {
12293 /* See if this can be inverted. If it can't, possibly because
12294 it was a floating-point inequality comparison, don't do
12295 anything. */
12299 }
12301 /* Convert A ? 1 : 0 to simply A. */
12304 /* If we try to convert OP0 to our type, the
12305 call to fold will try to move the conversion inside
12306 a COND, which will recurse. In that case, the COND_EXPR
12307 is probably the best choice, so leave it alone. */
12311 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12312 over COND_EXPR in cases such as floating point comparisons. */
12319 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12324 {
12325 /* sign_bit_p only checks ARG1 bits within A's precision.
12326 If <sign bit of A> has wider type than A, bits outside
12327 of A's precision in <sign bit of A> need to be checked.
12328 If they are all 0, this optimization needs to be done
12329 in unsigned A's type, if they are all 1 in signed A's type,
12330 otherwise this can't be done. */
12335 {
12337 HOST_WIDE_INT mask_hi;
12339 tree tem_type;
12347 {
12351 }
12352 else
12353 {
12357 }
12359 {
12363 }
12364 else
12370 {
12373 }
12376 {
12379 }
12380 else
12382 }
12389 arg1)));
12390 }
12392 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12393 already handled above. */
12398 {
12407 }
12409 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12410 is probably obsolete because the first operand should be a
12411 truth value (that's why we have the two cases above), but let's
12412 leave it in until we can confirm this for all front-ends. */
12423 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12429 arg1);
12431 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12435 {
12436 /* Only perform transformation if ARG0 is easily inverted. */
12441 arg1);
12442 }
12444 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
12448 {
12449 /* Only perform transformation if ARG0 is easily inverted. */
12454 op2);
12455 }
12457 /* Convert A ? 1 : B into A || B if A and B are truth values. */
12463 op2);
12468 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
12469 of fold_ternary on them. */
12477 {
12486 {
12492 else
12494 }
12495 }
12501 }
12503 /* Perform constant folding and related simplification of EXPR.
12504 The related simplifications include x*1 => x, x*0 => 0, etc.,
12505 and application of the associative law.
12506 NOP_EXPR conversions may be removed freely (as long as we
12507 are careful not to change the type of the overall expression).
12508 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12509 but we can constant-fold them if they have constant operands. */
12511 #ifdef ENABLE_FOLD_CHECKING
12512 # define fold(x) fold_1 (x)
12514 static
12515 #endif
12516 tree
12518 {
12522 tree tem;
12524 /* Return right away if a constant. */
12528 /* CALL_EXPR-like objects with variable numbers of operands are
12529 treated specially. */
12531 {
12533 {
12536 }
12538 }
12542 {
12547 {
12565 }
12566 }
12569 {
12576 }
12578 #ifdef ENABLE_FOLD_CHECKING
12579 #undef fold
12585 /* When --enable-checking=fold, compute a digest of expr before
12586 and after actual fold call to see if fold did not accidentally
12587 change original expr. */
12589 tree
12591 {
12592 tree ret;
12595 htab_t ht;
12614 }
12616 void
12618 {
12621 htab_t ht;
12631 }
12633 static void
12635 {
12637 }
12639 static void
12641 {
12647 recursive_label:
12661 {
12662 /* Allow DECL_ASSEMBLER_NAME to be modified. */
12666 }
12671 {
12672 /* Allow these fields to be modified. */
12679 {
12682 }
12683 }
12691 {
12694 {
12708 }
12712 {
12725 }
12742 {
12748 }
12753 {
12757 }
12768 {
12771 }
12781 }
12782 }
12784 #endif
12786 /* Fold a unary tree expression with code CODE of type TYPE with an
12787 operand OP0. Return a folded expression if successful. Otherwise,
12788 return a tree expression with code CODE of type TYPE with an
12789 operand OP0. */
12791 tree
12793 {
12794 tree tem;
12795 #ifdef ENABLE_FOLD_CHECKING
12798 htab_t ht;
12805 #endif
12811 #ifdef ENABLE_FOLD_CHECKING
12819 #endif
12821 }
12823 /* Fold a binary tree expression with code CODE of type TYPE with
12824 operands OP0 and OP1. Return a folded expression if successful.
12825 Otherwise, return a tree expression with code CODE of type TYPE
12826 with operands OP0 and OP1. */
12828 tree
12830 MEM_STAT_DECL)
12831 {
12832 tree tem;
12833 #ifdef ENABLE_FOLD_CHECKING
12839 htab_t ht;
12851 #endif
12857 #ifdef ENABLE_FOLD_CHECKING
12873 #endif
12875 }
12877 /* Fold a ternary tree expression with code CODE of type TYPE with
12878 operands OP0, OP1, and OP2. Return a folded expression if
12879 successful. Otherwise, return a tree expression with code CODE of
12880 type TYPE with operands OP0, OP1, and OP2. */
12882 tree
12884 MEM_STAT_DECL)
12885 {
12886 tree tem;
12887 #ifdef ENABLE_FOLD_CHECKING
12895 htab_t ht;
12912 #endif
12919 #ifdef ENABLE_FOLD_CHECKING
12943 #endif
12945 }
12947 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12948 arguments in ARGARRAY, and a null static chain.
12949 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12950 of type TYPE from the given operands as constructed by build_call_array. */
12952 tree
12954 {
12955 tree tem;
12956 #ifdef ENABLE_FOLD_CHECKING
12962 htab_t ht;
12976 #endif
12980 #ifdef ENABLE_FOLD_CHECKING
12997 #endif
12999 }
13001 /* Perform constant folding and related simplification of initializer
13002 expression EXPR. These behave identically to "fold_buildN" but ignore
13003 potential run-time traps and exceptions that fold must preserve. */
13005 #define START_FOLD_INIT \
13006 int saved_signaling_nans = flag_signaling_nans;\
13007 int saved_trapping_math = flag_trapping_math;\
13008 int saved_rounding_math = flag_rounding_math;\
13009 int saved_trapv = flag_trapv;\
13010 int saved_folding_initializer = folding_initializer;\
13011 flag_signaling_nans = 0;\
13012 flag_trapping_math = 0;\
13013 flag_rounding_math = 0;\
13014 flag_trapv = 0;\
13015 folding_initializer = 1;
13017 #define END_FOLD_INIT \
13018 flag_signaling_nans = saved_signaling_nans;\
13019 flag_trapping_math = saved_trapping_math;\
13020 flag_rounding_math = saved_rounding_math;\
13021 flag_trapv = saved_trapv;\
13022 folding_initializer = saved_folding_initializer;
13024 tree
13026 {
13027 tree result;
13028 START_FOLD_INIT;
13032 END_FOLD_INIT;
13034 }
13036 tree
13038 {
13039 tree result;
13040 START_FOLD_INIT;
13044 END_FOLD_INIT;
13046 }
13048 tree
13050 tree op2)
13051 {
13052 tree result;
13053 START_FOLD_INIT;
13057 END_FOLD_INIT;
13059 }
13061 tree
13064 {
13065 tree result;
13066 START_FOLD_INIT;
13070 END_FOLD_INIT;
13072 }
13074 #undef START_FOLD_INIT
13075 #undef END_FOLD_INIT
13077 /* Determine if first argument is a multiple of second argument. Return 0 if
13078 it is not, or we cannot easily determined it to be.
13080 An example of the sort of thing we care about (at this point; this routine
13081 could surely be made more general, and expanded to do what the *_DIV_EXPR's
13082 fold cases do now) is discovering that
13084 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13086 is a multiple of
13088 SAVE_EXPR (J * 8)
13090 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13092 This code also handles discovering that
13094 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13096 is a multiple of 8 so we don't have to worry about dealing with a
13097 possible remainder.
13099 Note that we *look* inside a SAVE_EXPR only to determine how it was
13100 calculated; it is not safe for fold to do much of anything else with the
13101 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13102 at run time. For example, the latter example above *cannot* be implemented
13103 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13104 evaluation time of the original SAVE_EXPR is not necessarily the same at
13105 the time the new expression is evaluated. The only optimization of this
13106 sort that would be valid is changing
13108 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13110 divided by 8 to
13112 SAVE_EXPR (I) * SAVE_EXPR (J)
13114 (where the same SAVE_EXPR (J) is used in the original and the
13115 transformed version). */
13117 int
13119 {
13127 {
13129 /* Bitwise and provides a power of two multiple. If the mask is
13130 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13133 /* FALLTHRU */
13146 {
13150 /* const_binop may not detect overflow correctly,
13151 so check for it explicitly here. */
13157 size_one_node,
13161 }
13165 /* Can't handle conversions from non-integral or wider integral type. */
13171 /* .. fall through ... */
13187 }
13188 }
13190 /* Return true if `t' is known to be non-negative. If the return
13191 value is based on the assumption that signed overflow is undefined,
13192 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13193 *STRICT_OVERFLOW_P. */
13195 bool
13197 {
13205 {
13207 /* Query VRP to see if it has recorded any information about
13208 the range of this object. */
13212 /* We can't return 1 if flag_wrapv is set because
13213 ABS_EXPR<INT_MIN> = INT_MIN. */
13217 {
13220 }
13232 strict_overflow_p)
13234 strict_overflow_p));
13236 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13237 both unsigned and at least 2 bits shorter than the result. */
13241 {
13246 {
13250 }
13251 }
13256 {
13257 /* x * x for floating point x is always non-negative. */
13261 strict_overflow_p)
13263 strict_overflow_p));
13264 }
13266 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13267 both unsigned and their total bits is shorter than the result. */
13271 {
13278 }
13284 strict_overflow_p)
13286 strict_overflow_p));
13297 strict_overflow_p)
13299 strict_overflow_p));
13310 strict_overflow_p);
13316 strict_overflow_p);
13320 strict_overflow_p);
13324 strict_overflow_p)
13326 strict_overflow_p));
13329 {
13334 {
13337 strict_overflow_p);
13339 {
13343 strict_overflow_p);
13344 }
13345 }
13347 {
13350 strict_overflow_p);
13354 }
13355 }
13359 {
13363 /* If the initializer is non-void, then it's a normal expression
13364 that will be assigned to the slot. */
13368 /* Otherwise, the initializer sets the slot in some way. One common
13369 way is an assignment statement at the end of the initializer. */
13371 {
13379 else
13381 }
13386 strict_overflow_p);
13389 }
13392 {
13396 {
13414 /* Always true. */
13418 /* sqrt(-0.0) is -0.0. */
13422 strict_overflow_p);
13455 /* True if the 1st argument is nonnegative. */
13457 strict_overflow_p);
13460 /* True if the 1st OR 2nd arguments are nonnegative. */
13462 strict_overflow_p)
13464 strict_overflow_p)));
13467 /* True if the 1st AND 2nd arguments are nonnegative. */
13469 strict_overflow_p)
13471 strict_overflow_p)));
13474 /* True if the 2nd argument is nonnegative. */
13476 strict_overflow_p);
13479 /* True if the 1st argument is nonnegative or the second
13480 argument is an even integer. */
13482 {
13486 }
13488 strict_overflow_p);
13491 /* True if the 1st argument is nonnegative or the second
13492 argument is an even integer valued real. */
13494 {
13495 REAL_VALUE_TYPE c;
13496 HOST_WIDE_INT n;
13501 {
13502 REAL_VALUE_TYPE cint;
13507 }
13508 }
13510 strict_overflow_p);
13514 }
13515 }
13517 /* ... fall through ... */
13521 /* Truth values evaluate to 0 or 1, which is nonnegative. */
13523 }
13525 /* We don't know sign of `t', so be conservative and return false. */
13527 }
13529 /* Return true if `t' is known to be non-negative. Handle warnings
13530 about undefined signed overflow. */
13532 bool
13534 {
13541 "determining that expression is always "
13543 WARN_STRICT_OVERFLOW_MISC);
13545 }
13547 /* Return true when T is an address and is known to be nonzero.
13548 For floating point we further ensure that T is not denormal.
13549 Similar logic is present in nonzero_address in rtlanal.h.
13551 If the return value is based on the assumption that signed overflow
13552 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13553 change *STRICT_OVERFLOW_P. */
13555 bool
13557 {
13561 /* Doing something useful for floating point would need more work. */
13566 {
13568 /* Query VRP to see if it has recorded any information about
13569 the range of this object. */
13574 strict_overflow_p);
13581 {
13582 /* With the presence of negative values it is hard
13583 to say something. */
13590 /* One of operands must be positive and the other non-negative. */
13591 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13592 overflows, on a twos-complement machine the sum of two
13593 nonnegative numbers can never be zero. */
13595 strict_overflow_p)
13597 strict_overflow_p));
13598 }
13603 {
13605 strict_overflow_p)
13607 strict_overflow_p))
13608 {
13611 }
13612 }
13616 {
13622 strict_overflow_p));
13623 }
13627 {
13633 /* Weak declarations may link to NULL. */
13637 /* Constants are never weak. */
13642 }
13650 {
13654 }
13663 {
13666 }
13673 {
13677 /* When both operands are nonzero, then MAX must be too. */
13679 strict_overflow_p))
13682 /* MAX where operand 0 is positive is positive. */
13684 strict_overflow_p);
13685 }
13686 /* MAX where operand 1 is positive is positive. */
13691 {
13695 }
13703 strict_overflow_p);
13708 strict_overflow_p);
13712 strict_overflow_p)
13714 strict_overflow_p));
13721 }
13723 }
13725 /* Return true when T is an address and is known to be nonzero.
13726 Handle warnings about undefined signed overflow. */
13728 bool
13730 {
13737 "determining that expression is always "
13739 WARN_STRICT_OVERFLOW_MISC);
13741 }
13743 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13744 attempt to fold the expression to a constant without modifying TYPE,
13745 OP0 or OP1.
13747 If the expression could be simplified to a constant, then return
13748 the constant. If the expression would not be simplified to a
13749 constant, then return NULL_TREE. */
13751 tree
13753 {
13756 }
13758 /* Given the components of a unary expression CODE, TYPE and OP0,
13759 attempt to fold the expression to a constant without modifying
13760 TYPE or OP0.
13762 If the expression could be simplified to a constant, then return
13763 the constant. If the expression would not be simplified to a
13764 constant, then return NULL_TREE. */
13766 tree
13768 {
13771 }
13773 /* If EXP represents referencing an element in a constant string
13774 (either via pointer arithmetic or array indexing), return the
13775 tree representing the value accessed, otherwise return NULL. */
13777 tree
13779 {
13783 {
13785 tree index;
13786 tree string;
13790 else
13791 {
13795 /* Optimize the special-case of a zero lower bound.
13797 We convert the low_bound to sizetype to avoid some problems
13798 with constant folding. (E.g. suppose the lower bound is 1,
13799 and its mode is QI. Without the conversion,l (ARRAY
13800 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13801 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
13806 }
13820 }
13822 }
13824 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13825 an integer constant or real constant.
13827 TYPE is the type of the result. */
13829 static tree
13831 {
13835 {
13837 {
13839 HOST_WIDE_INT high;
13847 }
13855 }
13858 }
13860 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13861 an integer constant or real constant.
13863 TYPE is the type of the result. */
13865 tree
13867 {
13871 {
13873 /* If the value is unsigned, then the absolute value is
13874 the same as the ordinary value. */
13877 /* Similarly, if the value is non-negative. */
13880 /* If the value is negative, then the absolute value is
13881 its negation. */
13882 else
13883 {
13885 HOST_WIDE_INT high;
13891 }
13897 else
13903 }
13906 }
13908 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13909 constant. TYPE is the type of the result. */
13911 static tree
13913 {
13923 }
13925 /* Given CODE, a relational operator, the target type, TYPE and two
13926 constant operands OP0 and OP1, return the result of the
13927 relational operation. If the result is not a compile time
13928 constant, then return NULL_TREE. */
13930 static tree
13932 {
13935 /* From here on, the only cases we handle are when the result is
13936 known to be a constant. */
13939 {
13943 /* Handle the cases where either operand is a NaN. */
13945 {
13947 {
13975 }
13978 }
13981 }
13983 /* Handle equality/inequality of complex constants. */
13985 {
13996 else
13998 }
14000 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14002 To compute GT, swap the arguments and do LT.
14003 To compute GE, do LT and invert the result.
14004 To compute LE, swap the arguments, do LT and invert the result.
14005 To compute NE, do EQ and invert the result.
14007 Therefore, the code below must handle only EQ and LT. */
14010 {
14015 }
14017 /* Note that it is safe to invert for real values here because we
14018 have already handled the one case that it matters. */
14022 {
14025 }
14027 /* Compute a result for LT or EQ if args permit;
14028 Otherwise return T. */
14030 {
14035 else
14037 }
14038 else
14044 }
14046 /* Build an expression for the a clean point containing EXPR with type TYPE.
14047 Don't build a cleanup point expression for EXPR which don't have side
14048 effects. */
14050 tree
14052 {
14053 /* If the expression does not have side effects then we don't have to wrap
14054 it with a cleanup point expression. */
14058 /* If the expression is a return, check to see if the expression inside the
14059 return has no side effects or the right hand side of the modify expression
14060 inside the return. If either don't have side effects set we don't need to
14061 wrap the expression in a cleanup point expression. Note we don't check the
14062 left hand side of the modify because it should always be a return decl. */
14064 {
14071 }
14074 }
14076 /* Build an expression for the address of T. Folds away INDIRECT_REF to
14077 avoid confusing the gimplify process. */
14079 tree
14081 {
14082 /* The size of the object is not relevant when talking about its address. */
14086 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
14089 {
14093 }
14094 else
14095 {
14104 }
14107 }
14109 tree
14111 {
14113 }
14115 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14116 of an indirection through OP0, or NULL_TREE if no simplification is
14117 possible. */
14119 tree
14121 {
14123 tree subtype;
14131 {
14134 /* *&CONST_DECL -> to the value of the const decl. */
14137 /* *&p => p; make sure to handle *&"str"[cst] here. */
14139 {
14143 else
14145 }
14146 /* *(foo *)&fooarray => fooarray[0] */
14149 {
14155 }
14156 /* *(foo *)&complexfoo => __real__ complexfoo */
14160 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14163 {
14167 }
14168 }
14170 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14173 {
14176 tree op00type;
14183 {
14187 }
14188 }
14190 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14193 {
14194 tree type_domain;
14201 }
14204 }
14206 /* Builds an expression for an indirection through T, simplifying some
14207 cases. */
14209 tree
14211 {
14217 else
14219 }
14221 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14223 tree
14225 {
14230 else
14232 }
14234 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14235 whose result is ignored. The type of the returned tree need not be
14236 the same as the original expression. */
14238 tree
14240 {
14246 {
14257 else
14263 {
14279 }
14284 }
14285 }
14287 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
14288 This can only be applied to objects of a sizetype. */
14290 tree
14292 {
14299 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14300 have to do anything. Only do this when we are not given a const,
14301 because in that case, this check is more expensive than just
14302 doing it. */
14304 {
14309 }
14311 /* If divisor is a power of two, simplify this to bit manipulation. */
14313 {
14315 {
14328 {
14329 high++;
14332 }
14336 }
14337 else
14338 {
14339 tree t;
14345 }
14346 }
14347 else
14348 {
14353 }
14356 }
14358 /* Likewise, but round down. */
14360 tree
14362 {
14369 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14370 have to do anything. Only do this when we are not given a const,
14371 because in that case, this check is more expensive than just
14372 doing it. */
14374 {
14379 }
14381 /* If divisor is a power of two, simplify this to bit manipulation. */
14383 {
14384 tree t;
14388 }
14389 else
14390 {
14395 }
14398 }
14400 /* Returns the pointer to the base of the object addressed by EXP and
14401 extracts the information about the offset of the access, storing it
14402 to PBITPOS and POFFSET. */
14404 static tree
14407 {
14408 tree core;
14411 HOST_WIDE_INT bitsize;
14414 {
14419 }
14420 else
14421 {
14425 }
14428 }
14430 /* Returns true if addresses of E1 and E2 differ by a constant, false
14431 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14433 bool
14435 {
14449 {
14459 }
14461 {
14462 /* If only one of the offsets is non-constant, the difference cannot
14463 be a constant. */
14465 }
14466 else
14471 }
14473 /* Simplify the floating point expression EXP when the sign of the
14474 result is not significant. Return NULL_TREE if no simplification
14475 is possible. */
14477 tree
14479 {
14483 {
14518 {
14521 {
14523 /* Strip copysign function call, return the 1st argument. */
14529 /* Strip sign ops from the argument of "odd" math functions. */
14531 {
14535 }
14537 }
14538 }
14543 }
14545 }