| blob | e1126219689c4bc1cac7dacb4634e183ef942b2a |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide, size_binop
31 and force_fit_type_double.
33 fold takes a tree as argument and returns a simplified tree.
35 size_binop takes a tree code for an arithmetic operation
36 and two operands that are trees, and produces a tree for the
37 result, assuming the type comes from `sizetype'.
39 size_int takes an integer value, and creates a tree constant
40 with type from `sizetype'.
42 force_fit_type_double takes a constant, an overflowable flag and a
43 prior overflow indicator. It forces the value to fit the type and
44 sets TREE_OVERFLOW.
46 Note: Since the folders get called on non-gimple code as well as
47 gimple code, we need to handle GIMPLE tuples as well as their
48 corresponding tree equivalents. */
70 /* Nonzero if we are folding constants inside an initializer; zero
71 otherwise. */
74 /* The following constants represent a bit based encoding of GCC's
75 comparison operators. This encoding simplifies transformations
76 on relational comparison operators, such as AND and OR. */
94 };
116 HOST_WIDE_INT *,
152 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
153 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
154 and SUM1. Then this yields nonzero if overflow occurred during the
155 addition.
157 Overflow occurs if A and B have the same sign, but A and SUM differ in
158 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
159 sign. */
160 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
161 \f
162 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
163 We do that by representing the two-word integer in 4 words, with only
164 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
165 number. The value of the word is LOWPART + HIGHPART * BASE. */
167 #define LOWPART(x) \
168 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
169 #define HIGHPART(x) \
170 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
171 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
173 /* Unpack a two-word integer into 4 words.
174 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
175 WORDS points to the array of HOST_WIDE_INTs. */
177 static void
179 {
184 }
186 /* Pack an array of 4 words into a two-word integer.
187 WORDS points to the array of words.
188 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
190 static void
193 {
196 }
197 \f
198 /* Force the double-word integer L1, H1 to be within the range of the
199 integer type TYPE. Stores the properly truncated and sign-extended
200 double-word integer in *LV, *HV. Returns true if the operation
201 overflows, that is, argument and result are different. */
203 int
206 {
212 /* Size types *are* sign extended. */
217 /* First clear all bits that are beyond the type's precision. */
219 ;
222 else
223 {
227 }
229 /* Then do sign extension if necessary. */
235 {
236 /* Sign extend top half? */
240 }
242 {
245 }
246 else
247 {
248 /* Sign extend bottom half? */
250 {
253 }
254 }
259 /* If the value didn't fit, signal overflow. */
261 }
263 /* We force the double-int HIGH:LOW to the range of the type TYPE by
264 sign or zero extending it.
265 OVERFLOWABLE indicates if we are interested
266 in overflow of the value, when >0 we are only interested in signed
267 overflow, for <0 we are interested in any overflow. OVERFLOWED
268 indicates whether overflow has already occurred. CONST_OVERFLOWED
269 indicates whether constant overflow has already occurred. We force
270 T's value to be within range of T's type (by setting to 0 or 1 all
271 the bits outside the type's range). We set TREE_OVERFLOWED if,
272 OVERFLOWED is nonzero,
273 or OVERFLOWABLE is >0 and signed overflow occurs
274 or OVERFLOWABLE is <0 and any overflow occurs
275 We return a new tree node for the extended double-int. The node
276 is shared if no overflow flags are set. */
278 tree
282 {
286 /* Size types *are* sign extended. */
293 /* If we need to set overflow flags, return a new unshared node. */
295 {
299 {
306 }
307 }
309 /* Else build a shared node. */
311 }
312 \f
313 /* Add two doubleword integers with doubleword result.
314 Return nonzero if the operation overflows according to UNSIGNED_P.
315 Each argument is given as two `HOST_WIDE_INT' pieces.
316 One argument is L1 and H1; the other, L2 and H2.
317 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
319 int
324 {
326 HOST_WIDE_INT h;
336 else
338 }
340 /* Negate a doubleword integer with doubleword result.
341 Return nonzero if the operation overflows, assuming it's signed.
342 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
343 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
345 int
348 {
350 {
354 }
355 else
356 {
360 }
361 }
362 \f
363 /* Multiply two doubleword integers with doubleword result.
364 Return nonzero if the operation overflows according to UNSIGNED_P.
365 Each argument is given as two `HOST_WIDE_INT' pieces.
366 One argument is L1 and H1; the other, L2 and H2.
367 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
369 int
374 {
389 {
392 {
394 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
396 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
400 }
402 }
407 /* Unsigned overflow is immediate. */
411 /* Check for signed overflow by calculating the signed representation of the
412 top half of the result; it should agree with the low half's sign bit. */
414 {
417 }
419 {
422 }
424 }
425 \f
426 /* Shift the doubleword integer in L1, H1 left by COUNT places
427 keeping only PREC bits of result.
428 Shift right if COUNT is negative.
429 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
430 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
432 void
436 {
440 {
443 }
449 {
450 /* Shifting by the host word size is undefined according to the
451 ANSI standard, so we must handle this as a special case. */
454 }
456 {
459 }
460 else
461 {
465 }
467 /* Sign extend all bits that are beyond the precision. */
475 ;
477 {
480 }
481 else
482 {
486 }
487 }
489 /* Shift the doubleword integer in L1, H1 right by COUNT places
490 keeping only PREC bits of result. COUNT must be positive.
491 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
492 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
494 void
499 {
502 signmask = (arith
510 {
511 /* Shifting by the host word size is undefined according to the
512 ANSI standard, so we must handle this as a special case. */
515 }
517 {
520 }
521 else
522 {
526 }
528 /* Zero / sign extend all bits that are beyond the precision. */
531 {
534 }
536 ;
538 {
541 }
542 else
543 {
547 }
548 }
549 \f
550 /* Rotate the doubleword integer in L1, H1 left by COUNT places
551 keeping only PREC bits of result.
552 Rotate right if COUNT is negative.
553 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
555 void
559 {
571 }
573 /* Rotate the doubleword integer in L1, H1 left by COUNT places
574 keeping only PREC bits of result. COUNT must be positive.
575 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
577 void
581 {
593 }
594 \f
595 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
596 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
597 CODE is a tree code for a kind of division, one of
598 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
599 or EXACT_DIV_EXPR
600 It controls how the quotient is rounded to an integer.
601 Return nonzero if the operation overflows.
602 UNS nonzero says do unsigned division. */
604 int
607 HOST_WIDE_INT hnum_orig,
609 HOST_WIDE_INT hden_orig,
613 {
629 /* Calculate quotient sign and convert operands to unsigned. */
631 {
633 {
635 /* (minimum integer) / (-1) is the only overflow case. */
639 }
641 {
644 }
645 }
650 /* This unsigned division rounds toward zero. */
653 }
657 /* hden != 0 already checked. */
662 }
672 /* Special code for when the divisor < BASE. */
674 {
675 /* hnum != 0 already checked. */
677 {
681 }
682 }
683 else
684 {
685 /* Full double precision division,
686 with thanks to Don Knuth's "Seminumerical Algorithms". */
690 /* Find the highest nonzero divisor digit. */
693 {
696 }
698 /* Insure that the first digit of the divisor is at least BASE/2.
699 This is required by the quotient digit estimation algorithm. */
706 {
710 }
715 {
720 }
721 }
725 /* Main loop */
727 {
728 /* Guess the next quotient digit, quo_est, by dividing the first
729 two remaining dividend digits by the high order quotient digit.
730 quo_est is never low and is at most 2 high. */
737 else
740 /* Refine quo_est so it's usually correct, and at most one high. */
745 quo_est--;
747 /* Try QUO_EST as the quotient digit, by multiplying the
748 divisor by QUO_EST and subtracting from the remaining dividend.
749 Keep in mind that QUO_EST is the I - 1st digit. */
753 {
759 }
761 /* If quo_est was high by one, then num[i] went negative and
762 we need to correct things. */
764 {
765 quo_est--;
768 {
772 }
775 }
777 /* Store the quotient digit. */
779 }
780 }
784 finish_up:
785 /* If result is negative, make it so. */
789 /* Compute trial remainder: rem = num - (quo * den) */
795 {
804 {
805 /* quo = quo - 1; */
808 }
809 else
816 {
819 }
820 else
826 {
832 /* Get absolute values. */
838 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
847 {
849 /* quo = quo - 1; */
852 else
853 /* quo = quo + 1; */
856 }
857 else
859 }
864 }
866 /* Compute true remainder: rem = num - (quo * den) */
871 }
873 /* If ARG2 divides ARG1 with zero remainder, carries out the division
874 of type CODE and returns the quotient.
875 Otherwise returns NULL_TREE. */
877 tree
879 {
886 /* The sign of the division is according to operand two, that
887 does the correct thing for POINTER_PLUS_EXPR where we want
888 a signed division. */
905 }
906 \f
907 /* This is nonzero if we should defer warnings about undefined
908 overflow. This facility exists because these warnings are a
909 special case. The code to estimate loop iterations does not want
910 to issue any warnings, since it works with expressions which do not
911 occur in user code. Various bits of cleanup code call fold(), but
912 only use the result if it has certain characteristics (e.g., is a
913 constant); that code only wants to issue a warning if the result is
914 used. */
918 /* If a warning about undefined overflow is deferred, this is the
919 warning. Note that this may cause us to turn two warnings into
920 one, but that is fine since it is sufficient to only give one
921 warning per expression. */
925 /* If a warning about undefined overflow is deferred, this is the
926 level at which the warning should be emitted. */
930 /* Start deferring overflow warnings. We could use a stack here to
931 permit nested calls, but at present it is not necessary. */
933 void
935 {
937 }
939 /* Stop deferring overflow warnings. If there is a pending warning,
940 and ISSUE is true, then issue the warning if appropriate. STMT is
941 the statement with which the warning should be associated (used for
942 location information); STMT may be NULL. CODE is the level of the
943 warning--a warn_strict_overflow_code value. This function will use
944 the smaller of CODE and the deferred code when deciding whether to
945 issue the warning. CODE may be zero to mean to always use the
946 deferred code. */
948 void
950 {
952 location_t locus;
957 {
963 }
974 /* Use the smallest code level when deciding to issue the
975 warning. */
984 else
987 }
989 /* Stop deferring overflow warnings, ignoring any deferred
990 warnings. */
992 void
994 {
996 }
998 /* Whether we are deferring overflow warnings. */
1000 bool
1002 {
1004 }
1006 /* This is called when we fold something based on the fact that signed
1007 overflow is undefined. */
1009 static void
1011 {
1013 {
1016 {
1019 }
1020 }
1023 }
1024 \f
1025 /* Return true if the built-in mathematical function specified by CODE
1026 is odd, i.e. -f(x) == f(-x). */
1028 static bool
1030 {
1032 {
1066 }
1068 }
1070 /* Check whether we may negate an integer constant T without causing
1071 overflow. */
1073 bool
1075 {
1078 tree type;
1088 {
1093 }
1094 else
1099 }
1101 /* Determine whether an expression T can be cheaply negated using
1102 the function negate_expr without introducing undefined overflow. */
1104 static bool
1106 {
1107 tree type;
1116 {
1121 /* Check that -CST will not overflow type. */
1147 /* -(A + B) -> (-B) - A. */
1152 /* -(A + B) -> (-A) - B. */
1156 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1166 /* Fall through. */
1179 /* In general we can't negate A / B, because if A is INT_MIN and
1180 B is 1, we may turn this into INT_MIN / -1 which is undefined
1181 and actually traps on some architectures. But if overflow is
1182 undefined, we can negate, because - (INT_MIN / 1) is an
1183 overflow. */
1191 /* Negate -((double)float) as (double)(-float). */
1193 {
1197 }
1201 /* Negate -f(x) as f(-x). */
1207 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1209 {
1215 }
1220 }
1222 }
1224 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1225 simplification is possible.
1226 If negate_expr_p would return true for T, NULL_TREE will never be
1227 returned. */
1229 static tree
1231 {
1233 tree tem;
1236 {
1237 /* Convert - (~A) to A + 1. */
1253 /* Two's complement FP formats, such as c4x, may overflow. */
1263 {
1272 }
1294 {
1295 /* -(A + B) -> (-B) - A. */
1299 {
1303 }
1305 /* -(A + B) -> (-A) - B. */
1307 {
1311 }
1312 }
1316 /* - (A - B) -> B - A */
1328 /* Fall through. */
1332 {
1341 }
1349 /* In general we can't negate A / B, because if A is INT_MIN and
1350 B is 1, we may turn this into INT_MIN / -1 which is undefined
1351 and actually traps on some architectures. But if overflow is
1352 undefined, we can negate, because - (INT_MIN / 1) is an
1353 overflow. */
1355 {
1360 {
1367 }
1370 {
1377 }
1378 }
1382 /* Convert -((double)float) into (double)(-float). */
1384 {
1388 }
1392 /* Negate -f(x) as f(-x). */
1395 {
1401 }
1405 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1407 {
1412 {
1419 }
1420 }
1425 }
1428 }
1430 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1431 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1432 return NULL_TREE. */
1434 static tree
1436 {
1438 location_t loc;
1449 {
1452 }
1454 }
1455 \f
1456 /* Split a tree IN into a constant, literal and variable parts that could be
1457 combined with CODE to make IN. "constant" means an expression with
1458 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1459 commutative arithmetic operation. Store the constant part into *CONP,
1460 the literal in *LITP and return the variable part. If a part isn't
1461 present, set it to null. If the tree does not decompose in this way,
1462 return the entire tree as the variable part and the other parts as null.
1464 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1465 case, we negate an operand that was subtracted. Except if it is a
1466 literal for which we use *MINUS_LITP instead.
1468 If NEGATE_P is true, we are negating all of IN, again except a literal
1469 for which we use *MINUS_LITP instead.
1471 If IN is itself a literal or constant, return it as appropriate.
1473 Note that we do not guarantee that any of the three values will be the
1474 same type as IN, but they will have the same signedness and mode. */
1476 static tree
1479 {
1486 /* Strip any conversions that don't change the machine mode or signedness. */
1495 /* We can associate addition and subtraction together (even
1496 though the C standard doesn't say so) for integers because
1497 the value is not affected. For reals, the value might be
1498 affected, so we can't. */
1501 {
1507 /* First see if either of the operands is a literal, then a constant. */
1520 /* If we haven't dealt with either operand, this is not a case we can
1521 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1526 else
1529 /* Now do any needed negations. */
1536 }
1539 else
1543 {
1550 }
1553 }
1555 /* Re-associate trees split by the above function. T1 and T2 are
1556 either expressions to associate or null. Return the new
1557 expression, if any. LOC is the location of the new expression. If
1558 we build an operation, do it in TYPE and with CODE. */
1560 static tree
1562 {
1563 tree tem;
1570 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1571 try to fold this since we will have infinite recursion. But do
1572 deal with any NEGATE_EXPRs. */
1575 {
1577 {
1586 }
1588 {
1591 }
1596 }
1600 associate_trees_exit:
1603 }
1604 \f
1605 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1606 for use in int_const_binop, size_binop and size_diffop. */
1608 static bool
1610 {
1617 {
1626 }
1631 }
1634 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1635 to produce a new constant. Return NULL_TREE if we don't know how
1636 to evaluate CODE at compile-time.
1638 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1640 tree
1642 {
1646 HOST_WIDE_INT hi;
1648 HOST_WIDE_INT garbageh;
1649 tree t;
1652 int is_sizetype
1662 {
1678 /* It's unclear from the C standard whether shifts can overflow.
1679 The following code ignores overflow; perhaps a C standard
1680 interpretation ruling is needed. */
1709 /* This is a shortcut for a common special case. */
1714 {
1720 }
1722 /* ... fall through ... */
1728 {
1731 }
1734 {
1737 }
1744 /* This is a shortcut for a common special case. */
1749 {
1754 }
1756 /* ... fall through ... */
1774 else
1780 else
1786 }
1789 {
1792 /* Propagate overflow flags ourselves. */
1795 {
1798 }
1799 }
1800 else
1806 }
1808 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1809 constant. We assume ARG1 and ARG2 have the same data type, or at least
1810 are the same kind of constant and the same machine mode. Return zero if
1811 combining the constants is not allowed in the current operating mode.
1813 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1815 static tree
1817 {
1818 /* Sanity check for the recursive cases. */
1829 {
1831 REAL_VALUE_TYPE d1;
1832 REAL_VALUE_TYPE d2;
1833 REAL_VALUE_TYPE value;
1834 REAL_VALUE_TYPE result;
1838 /* The following codes are handled by real_arithmetic. */
1840 {
1851 }
1859 /* Don't perform operation if we honor signaling NaNs and
1860 either operand is a NaN. */
1865 /* Don't perform operation if it would raise a division
1866 by zero exception. */
1872 /* If either operand is a NaN, just return it. Otherwise, set up
1873 for floating-point trap; we return an overflow. */
1882 /* Don't constant fold this floating point operation if
1883 the result has overflowed and flag_trapping_math. */
1891 /* Don't constant fold this floating point operation if the
1892 result may dependent upon the run-time rounding mode and
1893 flag_rounding_math is set, or if GCC's software emulation
1894 is unable to accurately represent the result. */
1904 }
1907 {
1908 FIXED_VALUE_TYPE f1;
1909 FIXED_VALUE_TYPE f2;
1910 FIXED_VALUE_TYPE result;
1915 /* The following codes are handled by fixed_arithmetic. */
1917 {
1934 }
1941 /* Propagate overflow flags. */
1945 }
1948 {
1957 {
1968 mpc_mul);
1973 notrunc);
1977 notrunc);
1984 mpc_div);
1985 /* Fallthru ... */
1991 {
1992 /* Keep this algorithm in sync with
1993 tree-complex.c:expand_complex_div_straight().
1995 Expand complex division to scalars, straightforward algorithm.
1996 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1997 t = br*br + bi*bi
1998 */
1999 tree magsquared
2003 notrunc);
2004 tree t1
2008 notrunc);
2009 tree t2
2013 notrunc);
2017 }
2018 else
2019 {
2020 /* Keep this algorithm in sync with
2021 tree-complex.c:expand_complex_div_wide().
2023 Expand complex division to scalars, modified algorithm to minimize
2024 overflow with wide input ranges. */
2030 {
2031 /* In the TRUE branch, we compute
2032 ratio = br/bi;
2033 div = (br * ratio) + bi;
2034 tr = (ar * ratio) + ai;
2035 ti = (ai * ratio) - ar;
2036 tr = tr / div;
2037 ti = ti / div; */
2041 notrunc),
2042 notrunc);
2050 }
2051 else
2052 {
2053 /* In the FALSE branch, we compute
2054 ratio = d/c;
2055 divisor = (d * ratio) + c;
2056 tr = (b * ratio) + a;
2057 ti = b - (a * ratio);
2058 tr = tr / div;
2059 ti = ti / div; */
2063 notrunc),
2064 notrunc);
2073 }
2074 }
2079 }
2083 }
2086 {
2098 {
2101 /* The trailing elements can be empty and should be treated as 0 */
2104 else
2105 {
2108 }
2112 else
2113 {
2116 }
2120 /* It is possible that const_binop cannot handle the given
2121 code and return NULL_TREE */
2126 }
2128 }
2130 }
2132 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2133 indicates which particular sizetype to create. */
2135 tree
2137 {
2139 }
2140 \f
2141 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2142 is a tree code. The type of the result is taken from the operands.
2143 Both must be equivalent integer types, ala int_binop_types_match_p.
2144 If the operands are constant, so is the result. */
2146 tree
2148 {
2157 /* Handle the special case of two integer constants faster. */
2159 {
2160 /* And some specific cases even faster than that. */
2162 {
2167 }
2169 {
2172 }
2174 {
2177 }
2179 /* Handle general case of two integer constants. */
2181 }
2184 }
2186 /* Given two values, either both of sizetype or both of bitsizetype,
2187 compute the difference between the two values. Return the value
2188 in signed type corresponding to the type of the operands. */
2190 tree
2192 {
2194 tree ctype;
2199 /* If the type is already signed, just do the simple thing. */
2207 else
2210 /* If either operand is not a constant, do the conversions to the signed
2211 type and subtract. The hardware will do the right thing with any
2212 overflow in the subtraction. */
2218 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2219 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2220 overflow) and negate (which can't either). Special-case a result
2221 of zero while we're here. */
2227 else
2231 MINUS_EXPR,
2233 }
2234 \f
2235 /* A subroutine of fold_convert_const handling conversions of an
2236 INTEGER_CST to another integer type. */
2238 static tree
2240 {
2241 tree t;
2243 /* Given an integer constant, make new constant with new type,
2244 appropriately sign-extended or truncated. */
2247 /* Don't set the overflow when
2248 converting from a pointer, */
2250 /* or to a sizetype with same signedness
2251 and the precision is unchanged.
2252 ??? sizetype is always sign-extended,
2253 but its signedness depends on the
2254 frontend. Thus we see spurious overflows
2255 here if we do not check this. */
2270 }
2272 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2273 to an integer type. */
2275 static tree
2277 {
2279 tree t;
2281 /* The following code implements the floating point to integer
2282 conversion rules required by the Java Language Specification,
2283 that IEEE NaNs are mapped to zero and values that overflow
2284 the target precision saturate, i.e. values greater than
2285 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2286 are mapped to INT_MIN. These semantics are allowed by the
2287 C and C++ standards that simply state that the behavior of
2288 FP-to-integer conversion is unspecified upon overflow. */
2291 REAL_VALUE_TYPE r;
2295 {
2302 }
2304 /* If R is NaN, return zero and show we have an overflow. */
2306 {
2310 }
2312 /* See if R is less than the lower bound or greater than the
2313 upper bound. */
2316 {
2320 {
2324 }
2325 }
2328 {
2331 {
2334 {
2338 }
2339 }
2340 }
2348 }
2350 /* A subroutine of fold_convert_const handling conversions of a
2351 FIXED_CST to an integer type. */
2353 static tree
2355 {
2356 tree t;
2360 /* Right shift FIXED_CST to temp by fbit. */
2364 {
2369 /* Left shift temp to temp_trunc by fbit. */
2374 }
2375 else
2376 {
2381 }
2383 /* If FIXED_CST is negative, we need to round the value toward 0.
2384 By checking if the fractional bits are not zero to add 1 to temp. */
2387 {
2388 double_int one;
2392 }
2394 /* Given a fixed-point constant, make new constant with new type,
2395 appropriately sign-extended or truncated. */
2403 }
2405 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2406 to another floating point type. */
2408 static tree
2410 {
2411 REAL_VALUE_TYPE value;
2412 tree t;
2417 /* If converting an infinity or NAN to a representation that doesn't
2418 have one, set the overflow bit so that we can produce some kind of
2419 error message at the appropriate point if necessary. It's not the
2420 most user-friendly message, but it's better than nothing. */
2427 /* Regular overflow, conversion produced an infinity in a mode that
2428 can't represent them. */
2433 else
2436 }
2438 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2439 to a floating point type. */
2441 static tree
2443 {
2444 REAL_VALUE_TYPE value;
2445 tree t;
2452 }
2454 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2455 to another fixed-point type. */
2457 static tree
2459 {
2460 FIXED_VALUE_TYPE value;
2461 tree t;
2468 /* Propagate overflow flags. */
2472 }
2474 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2475 to a fixed-point type. */
2477 static tree
2479 {
2480 FIXED_VALUE_TYPE value;
2481 tree t;
2490 /* Propagate overflow flags. */
2494 }
2496 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2497 to a fixed-point type. */
2499 static tree
2501 {
2502 FIXED_VALUE_TYPE value;
2503 tree t;
2511 /* Propagate overflow flags. */
2515 }
2517 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2518 type TYPE. If no simplification can be done return NULL_TREE. */
2520 static tree
2522 {
2528 {
2535 }
2537 {
2544 }
2546 {
2553 }
2555 }
2557 /* Construct a vector of zero elements of vector type TYPE. */
2559 static tree
2561 {
2572 }
2574 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2576 bool
2578 {
2593 {
2612 }
2613 }
2615 /* Convert expression ARG to type TYPE. Used by the middle-end for
2616 simple conversions in preference to calling the front-end's convert. */
2618 tree
2620 {
2622 tree tem;
2636 {
2639 /* Handle conversions between pointers to different address spaces. */
2644 /* fall through */
2649 {
2653 }
2667 {
2671 }
2673 {
2677 }
2679 {
2683 }
2686 {
2704 }
2709 {
2713 }
2716 {
2730 }
2734 {
2743 integer_zero_node));
2745 {
2749 {
2755 }
2763 }
2767 }
2785 }
2786 fold_convert_exit:
2789 }
2790 \f
2791 /* Return false if expr can be assumed not to be an lvalue, true
2792 otherwise. */
2794 static bool
2796 {
2797 /* We only need to wrap lvalue tree codes. */
2799 {
2831 /* Assume the worst for front-end tree codes. */
2835 }
2838 }
2840 /* Return an expr equal to X but certainly not valid as an lvalue. */
2842 tree
2844 {
2845 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2846 us. */
2855 }
2857 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2858 Zero means allow extended lvalues. */
2862 /* When pedantic, return an expr equal to X but certainly not valid as a
2863 pedantic lvalue. Otherwise, return X. */
2865 static tree
2867 {
2872 }
2873 \f
2874 /* Given a tree comparison code, return the code that is the logical inverse
2875 of the given code. It is not safe to do this for floating-point
2876 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2877 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2879 enum tree_code
2881 {
2886 {
2917 }
2918 }
2920 /* Similar, but return the comparison that results if the operands are
2921 swapped. This is safe for floating-point. */
2923 enum tree_code
2925 {
2927 {
2953 }
2954 }
2957 /* Convert a comparison tree code from an enum tree_code representation
2958 into a compcode bit-based encoding. This function is the inverse of
2959 compcode_to_comparison. */
2961 static enum comparison_code
2963 {
2965 {
2996 }
2997 }
2999 /* Convert a compcode bit-based encoding of a comparison operator back
3000 to GCC's enum tree_code representation. This function is the
3001 inverse of comparison_to_compcode. */
3003 static enum tree_code
3005 {
3007 {
3038 }
3039 }
3041 /* Return a tree for the comparison which is the combination of
3042 doing the AND or OR (depending on CODE) of the two operations LCODE
3043 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
3044 the possibility of trapping if the mode has NaNs, and return NULL_TREE
3045 if this makes the transformation invalid. */
3047 tree
3052 {
3059 {
3070 }
3073 {
3074 /* Eliminate unordered comparisons, as well as LTGT and ORD
3075 which are not used unless the mode has NaNs. */
3081 }
3083 {
3084 /* Check that the original operation and the optimized ones will trap
3085 under the same condition. */
3096 /* In a short-circuited boolean expression the LHS might be
3097 such that the RHS, if evaluated, will never trap. For
3098 example, in ORD (x, y) && (x < y), we evaluate the RHS only
3099 if neither x nor y is NaN. (This is a mixed blessing: for
3100 example, the expression above will never trap, hence
3101 optimizing it to x < y would be invalid). */
3106 /* If the comparison was short-circuited, and only the RHS
3107 trapped, we may now generate a spurious trap. */
3112 /* If we changed the conditions that cause a trap, we lose. */
3115 }
3121 else
3122 {
3127 }
3128 }
3129 \f
3130 /* Return nonzero if two operands (typically of the same tree node)
3131 are necessarily equal. If either argument has side-effects this
3132 function returns zero. FLAGS modifies behavior as follows:
3134 If OEP_ONLY_CONST is set, only return nonzero for constants.
3135 This function tests whether the operands are indistinguishable;
3136 it does not test whether they are equal using C's == operation.
3137 The distinction is important for IEEE floating point, because
3138 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3139 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3141 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3142 even though it may hold multiple values during a function.
3143 This is because a GCC tree node guarantees that nothing else is
3144 executed between the evaluation of its "operands" (which may often
3145 be evaluated in arbitrary order). Hence if the operands themselves
3146 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3147 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3148 unset means assuming isochronic (or instantaneous) tree equivalence.
3149 Unless comparing arbitrary expression trees, such as from different
3150 statements, this flag can usually be left unset.
3152 If OEP_PURE_SAME is set, then pure functions with identical arguments
3153 are considered the same. It is used when the caller has other ways
3154 to ensure that global memory is unchanged in between. */
3156 int
3158 {
3159 /* If either is ERROR_MARK, they aren't equal. */
3163 /* Check equality of integer constants before bailing out due to
3164 precision differences. */
3168 /* If both types don't have the same signedness, then we can't consider
3169 them equal. We must check this before the STRIP_NOPS calls
3170 because they may change the signedness of the arguments. As pointers
3171 strictly don't have a signedness, require either two pointers or
3172 two non-pointers as well. */
3177 /* We cannot consider pointers to different address space equal. */
3183 /* If both types don't have the same precision, then it is not safe
3184 to strip NOPs. */
3191 /* In case both args are comparisons but with different comparison
3192 code, try to swap the comparison operands of one arg to produce
3193 a match and compare that variant. */
3197 {
3205 }
3208 /* This is needed for conversions and for COMPONENT_REF.
3209 Might as well play it safe and always test this. */
3215 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3216 We don't care about side effects in that case because the SAVE_EXPR
3217 takes care of that for us. In all other cases, two expressions are
3218 equal if they have no side effects. If we have two identical
3219 expressions with side effects that should be treated the same due
3220 to the only side effects being identical SAVE_EXPR's, that will
3221 be detected in the recursive calls below. */
3227 /* Next handle constant cases, those for which we can return 1 even
3228 if ONLY_CONST is set. */
3231 {
3246 {
3247 /* If we do not distinguish between signed and unsigned zero,
3248 consider them equal. */
3251 }
3255 {
3261 {
3263 flags))
3267 }
3270 }
3274 flags)
3276 flags));
3289 }
3294 /* Define macros to test an operand from arg0 and arg1 for equality and a
3295 variant that allows null and views null as being different from any
3296 non-null value. In the latter case, if either is null, the both
3297 must be; otherwise, do the normal comparison. */
3298 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3299 TREE_OPERAND (arg1, N), flags)
3301 #define OP_SAME_WITH_NULL(N) \
3302 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3303 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3306 {
3308 /* Two conversions are equal only if signedness and modes match. */
3310 {
3311 CASE_CONVERT:
3319 }
3329 /* For commutative ops, allow the other order. */
3337 /* If either of the pointer (or reference) expressions we are
3338 dereferencing contain a side effect, these cannot be equal. */
3344 {
3354 /* Operands 2 and 3 may be null.
3355 Compare the array index by value if it is constant first as we
3356 may have different types but same value here. */
3365 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3366 may be NULL when we're called to compare MEM_EXPRs. */
3376 }
3380 {
3395 /* Otherwise take into account this is a commutative operation. */
3406 }
3410 {
3412 /* If the CALL_EXPRs call different functions, then they
3413 clearly can not be equal. */
3415 flags))
3418 {
3422 else
3426 }
3428 /* Now see if all the arguments are the same. */
3429 {
3440 /* If we get here and both argument lists are exhausted
3441 then the CALL_EXPRs are equal. */
3443 }
3446 }
3449 /* Consider __builtin_sqrt equal to sqrt. */
3457 }
3459 #undef OP_SAME
3460 #undef OP_SAME_WITH_NULL
3461 }
3462 \f
3463 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3464 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3466 When in doubt, return 0. */
3468 static int
3470 {
3482 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3483 and see if the inner values are the same. This removes any
3484 signedness comparison, which doesn't matter here. */
3491 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3492 actual comparison operand, ARG0.
3494 First throw away any conversions to wider types
3495 already present in the operands. */
3504 {
3507 /* Make sure shorter operand is extended the right way
3508 to match the longer operand. */
3514 }
3517 }
3518 \f
3519 /* See if ARG is an expression that is either a comparison or is performing
3520 arithmetic on comparisons. The comparisons must only be comparing
3521 two different values, which will be stored in *CVAL1 and *CVAL2; if
3522 they are nonzero it means that some operands have already been found.
3523 No variables may be used anywhere else in the expression except in the
3524 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3525 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3527 If this is true, return 1. Otherwise, return zero. */
3529 static int
3531 {
3535 /* We can handle some of the tcc_expression cases here. */
3545 {
3546 /* If we've already found a CVAL1 or CVAL2, this expression is
3547 two complex to handle. */
3553 }
3556 {
3579 /* First see if we can handle the first operand, then the second. For
3580 the second operand, we know *CVAL1 can't be zero. It must be that
3581 one side of the comparison is each of the values; test for the
3582 case where this isn't true by failing if the two operands
3583 are the same. */
3592 ;
3596 ;
3597 else
3601 ;
3605 ;
3606 else
3613 }
3614 }
3615 \f
3616 /* ARG is a tree that is known to contain just arithmetic operations and
3617 comparisons. Evaluate the operations in the tree substituting NEW0 for
3618 any occurrence of OLD0 as an operand of a comparison and likewise for
3619 NEW1 and OLD1. */
3621 static tree
3624 {
3629 /* We can handle some of the tcc_expression cases here. */
3637 {
3652 {
3671 }
3672 /* Fall through - ??? */
3675 {
3679 /* We need to check both for exact equality and tree equality. The
3680 former will be true if the operand has a side-effect. In that
3681 case, we know the operand occurred exactly once. */
3694 }
3698 }
3699 }
3700 \f
3701 /* Return a tree for the case when the result of an expression is RESULT
3702 converted to TYPE and OMITTED was previously an operand of the expression
3703 but is now not needed (e.g., we folded OMITTED * 0).
3705 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3706 the conversion of RESULT to TYPE. */
3708 tree
3710 {
3713 /* If the resulting operand is an empty statement, just return the omitted
3714 statement casted to void. */
3716 {
3719 }
3722 {
3725 }
3729 omit_one_operand_exit:
3732 }
3734 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3736 static tree
3738 tree omitted)
3739 {
3742 /* If the resulting operand is an empty statement, just return the omitted
3743 statement casted to void. */
3745 {
3748 }
3751 {
3754 }
3758 pedantic_omit_one_operand_exit:
3761 }
3763 /* Return a tree for the case when the result of an expression is RESULT
3764 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3765 of the expression but are now not needed.
3767 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3768 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3769 evaluated before OMITTED2. Otherwise, if neither has side effects,
3770 just do the conversion of RESULT to TYPE. */
3772 tree
3775 {
3779 {
3782 }
3784 {
3787 }
3790 }
3792 \f
3793 /* Return a simplified tree node for the truth-negation of ARG. This
3794 never alters ARG itself. We assume that ARG is an operation that
3795 returns a truth value (0 or 1).
3797 FIXME: one would think we would fold the result, but it causes
3798 problems with the dominator optimizer. */
3800 tree
3802 {
3807 /* If this is a comparison, we can simply invert it, except for
3808 floating-point non-equality comparisons, in which case we just
3809 enclose a TRUTH_NOT_EXPR around what we have. */
3812 {
3815 && flag_trapping_math
3827 }
3830 {
3859 /* Here we can invert either operand. We invert the first operand
3860 unless the second operand is a TRUTH_NOT_EXPR in which case our
3861 result is the XOR of the first operand with the inside of the
3862 negation of the second operand. */
3867 else
3901 {
3912 /* A COND_EXPR may have a throw as one operand, which
3913 then has void type. Just leave void operands
3914 as they are. */
3921 }
3938 CASE_CONVERT:
3940 {
3943 }
3945 /* ... fall through ... */
3976 }
3982 }
3984 /* Return a simplified tree node for the truth-negation of ARG. This
3985 never alters ARG itself. We assume that ARG is an operation that
3986 returns a truth value (0 or 1).
3988 FIXME: one would think we would fold the result, but it causes
3989 problems with the dominator optimizer. */
3991 tree
3993 {
3994 tree tem;
4001 {
4004 }
4007 }
4009 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
4010 operands are another bit-wise operation with a common input. If so,
4011 distribute the bit operations to save an operation and possibly two if
4012 constants are involved. For example, convert
4013 (A | B) & (A | C) into A | (B & C)
4014 Further simplification will occur if B and C are constants.
4016 If this optimization cannot be done, 0 will be returned. */
4018 static tree
4021 {
4022 tree common;
4032 {
4036 }
4038 {
4042 }
4044 {
4048 }
4050 {
4054 }
4055 else
4063 }
4065 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
4066 with code CODE. This optimization is unsafe. */
4067 static tree
4070 {
4074 /* (A / C) +- (B / C) -> (A +- B) / C. */
4084 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
4089 {
4101 }
4104 }
4105 \f
4106 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4107 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
4109 static tree
4112 {
4116 {
4123 }
4138 }
4140 /* Optimize a bit-field compare.
4142 There are two cases: First is a compare against a constant and the
4143 second is a comparison of two items where the fields are at the same
4144 bit position relative to the start of a chunk (byte, halfword, word)
4145 large enough to contain it. In these cases we can avoid the shift
4146 implicit in bitfield extractions.
4148 For constants, we emit a compare of the shifted constant with the
4149 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4150 compared. For two fields at the same position, we do the ANDs with the
4151 similar mask and compare the result of the ANDs.
4153 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4154 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4155 are the left and right operands of the comparison, respectively.
4157 If the optimization described above can be done, we return the resulting
4158 tree. Otherwise we return zero. */
4160 static tree
4163 {
4172 tree mask;
4173 tree offset;
4175 /* Get all the information about the extractions being done. If the bit size
4176 if the same as the size of the underlying object, we aren't doing an
4177 extraction at all and so can do nothing. We also don't want to
4178 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4179 then will no longer be able to replace it. */
4187 {
4188 /* If this is not a constant, we can only do something if bit positions,
4189 sizes, and signedness are the same. */
4197 }
4199 /* See if we can find a mode to refer to this field. We should be able to,
4200 but fail if we can't. */
4209 /* Set signed and unsigned types of the precision of this mode for the
4210 shifts below. */
4214 /* Compute the bit position and size for the new reference and our offset
4215 within it. If the new reference is the same size as the original, we
4216 won't optimize anything, so return zero. */
4226 /* Make the mask to be used against the extracted field. */
4233 /* If not comparing with constant, just rework the comparison
4234 and return. */
4238 unsigned_type,
4241 mask),
4244 unsigned_type,
4247 mask));
4249 /* Otherwise, we are handling the constant case. See if the constant is too
4250 big for the field. Warn and return a tree of for 0 (false) if so. We do
4251 this not only for its own sake, but to avoid having to test for this
4252 error case below. If we didn't, we might generate wrong code.
4254 For unsigned fields, the constant shifted right by the field length should
4255 be all zero. For signed fields, the high-order bits should agree with
4256 the sign bit. */
4259 {
4264 {
4268 }
4269 }
4270 else
4271 {
4276 {
4280 }
4281 }
4283 /* Single-bit compares should always be against zero. */
4285 {
4288 }
4290 /* Make a new bitfield reference, shift the constant over the
4291 appropriate number of bits and mask it with the computed mask
4292 (in case this was a signed field). If we changed it, make a new one. */
4295 {
4298 }
4308 rhs);
4311 }
4312 \f
4313 /* Subroutine for fold_truthop: decode a field reference.
4315 If EXP is a comparison reference, we return the innermost reference.
4317 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4318 set to the starting bit number.
4320 If the innermost field can be completely contained in a mode-sized
4321 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4323 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4324 otherwise it is not changed.
4326 *PUNSIGNEDP is set to the signedness of the field.
4328 *PMASK is set to the mask used. This is either contained in a
4329 BIT_AND_EXPR or derived from the width of the field.
4331 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4333 Return 0 if this is not a component reference or is one that we can't
4334 do anything with. */
4336 static tree
4341 {
4345 tree unsigned_type;
4348 /* All the optimizations using this function assume integer fields.
4349 There are problems with FP fields since the type_for_size call
4350 below can fail for, e.g., XFmode. */
4354 /* We are interested in the bare arrangement of bits, so strip everything
4355 that doesn't affect the machine mode. However, record the type of the
4356 outermost expression if it may matter below. */
4363 {
4369 }
4378 /* If the number of bits in the reference is the same as the bitsize of
4379 the outer type, then the outer type gives the signedness. Otherwise
4380 (in case of a small bitfield) the signedness is unchanged. */
4384 /* Compute the mask to access the bitfield. */
4393 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4401 }
4403 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4404 bit positions. */
4406 static int
4408 {
4411 tree tmask;
4415 return
4422 }
4424 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4425 represents the sign bit of EXP's type. If EXP represents a sign
4426 or zero extension, also test VAL against the unextended type.
4427 The return value is the (sub)expression whose sign bit is VAL,
4428 or NULL_TREE otherwise. */
4430 static tree
4432 {
4436 tree t;
4438 /* Tree EXP must have an integral type. */
4443 /* Tree VAL must be an integer constant. */
4450 {
4457 }
4458 else
4459 {
4466 }
4468 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4469 treat VAL as if it were unsigned. */
4474 /* Handle extension from a narrower type. */
4480 }
4482 /* Subroutine for fold_truthop: determine if an operand is simple enough
4483 to be evaluated unconditionally. */
4485 static int
4487 {
4488 /* Strip any conversions that don't change the machine mode. */
4497 /* Don't regard global variables as simple. They may be
4498 allocated in ways unknown to the compiler (shared memory,
4499 #pragma weak, etc). */
4502 /* Loading a static variable is unduly expensive, but global
4503 registers aren't expensive. */
4505 }
4506 \f
4507 /* The following functions are subroutines to fold_range_test and allow it to
4508 try to change a logical combination of comparisons into a range test.
4510 For example, both
4511 X == 2 || X == 3 || X == 4 || X == 5
4512 and
4513 X >= 2 && X <= 5
4514 are converted to
4515 (unsigned) (X - 2) <= 3
4517 We describe each set of comparisons as being either inside or outside
4518 a range, using a variable named like IN_P, and then describe the
4519 range with a lower and upper bound. If one of the bounds is omitted,
4520 it represents either the highest or lowest value of the type.
4522 In the comments below, we represent a range by two numbers in brackets
4523 preceded by a "+" to designate being inside that range, or a "-" to
4524 designate being outside that range, so the condition can be inverted by
4525 flipping the prefix. An omitted bound is represented by a "-". For
4526 example, "- [-, 10]" means being outside the range starting at the lowest
4527 possible value and ending at 10, in other words, being greater than 10.
4528 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4529 always false.
4531 We set up things so that the missing bounds are handled in a consistent
4532 manner so neither a missing bound nor "true" and "false" need to be
4533 handled using a special case. */
4535 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4536 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4537 and UPPER1_P are nonzero if the respective argument is an upper bound
4538 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4539 must be specified for a comparison. ARG1 will be converted to ARG0's
4540 type if both are specified. */
4542 static tree
4545 {
4546 tree tem;
4550 /* If neither arg represents infinity, do the normal operation.
4551 Else, if not a comparison, return infinity. Else handle the special
4552 comparison rules. Note that most of the cases below won't occur, but
4553 are handled for consistency. */
4556 {
4561 }
4566 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4567 for neither. In real maths, we cannot assume open ended ranges are
4568 the same. But, this is computer arithmetic, where numbers are finite.
4569 We can therefore make the transformation of any unbounded range with
4570 the value Z, Z being greater than any representable number. This permits
4571 us to treat unbounded ranges as equal. */
4575 {
4596 }
4599 }
4600 \f
4601 /* Given EXP, a logical expression, set the range it is testing into
4602 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4603 actually being tested. *PLOW and *PHIGH will be made of the same
4604 type as the returned expression. If EXP is not a comparison, we
4605 will most likely not be returning a useful value and range. Set
4606 *STRICT_OVERFLOW_P to true if the return value is only valid
4607 because signed overflow is undefined; otherwise, do not change
4608 *STRICT_OVERFLOW_P. */
4610 tree
4613 {
4621 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4622 and see if we can refine the range. Some of the cases below may not
4623 happen, but it doesn't seem worth worrying about this. We "continue"
4624 the outer loop when we've changed something; otherwise we "break"
4625 the switch, which will "break" the while. */
4631 {
4636 {
4648 }
4651 {
4658 /* We can only do something if the range is testing for zero
4659 and if the second operand is an integer constant. Note that
4660 saying something is "in" the range we make is done by
4661 complementing IN_P since it will set in the initial case of
4662 being not equal to zero; "out" is leaving it alone. */
4669 {
4690 }
4692 /* If this is an unsigned comparison, we also know that EXP is
4693 greater than or equal to zero. We base the range tests we make
4694 on that fact, so we record it here so we can parse existing
4695 range tests. We test arg0_type since often the return type
4696 of, e.g. EQ_EXPR, is boolean. */
4698 {
4702 NULL_TREE))
4707 /* If the high bound is missing, but we have a nonzero low
4708 bound, reverse the range so it goes from zero to the low bound
4709 minus 1. */
4711 {
4716 }
4717 }
4723 /* (-x) IN [a,b] -> x in [-b, -a] */
4735 /* ~ X -> -X - 1 */
4745 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4746 move a constant to the other side. */
4751 /* If EXP is signed, any overflow in the computation is undefined,
4752 so we don't worry about it so long as our computations on
4753 the bounds don't overflow. For unsigned, overflow is defined
4754 and this is exactly the right thing. */
4766 /* Check for an unsigned range which has wrapped around the maximum
4767 value thus making n_high < n_low, and normalize it. */
4769 {
4775 /* If the range is of the form +/- [ x+1, x ], we won't
4776 be able to normalize it. But then, it represents the
4777 whole range or the empty set, so make it
4778 +/- [ -, - ]. */
4782 else
4784 }
4785 else
4809 /* If we're converting arg0 from an unsigned type, to exp,
4810 a signed type, we will be doing the comparison as unsigned.
4811 The tests above have already verified that LOW and HIGH
4812 are both positive.
4814 So we have to ensure that we will handle large unsigned
4815 values the same way that the current signed bounds treat
4816 negative values. */
4819 {
4820 tree high_positive;
4821 tree equiv_type;
4822 /* For fixed-point modes, we need to pass the saturating flag
4823 as the 2nd parameter. */
4828 else
4832 /* A range without an upper bound is, naturally, unbounded.
4833 Since convert would have cropped a very large value, use
4834 the max value for the destination type. */
4835 high_positive
4842 high_positive),
4845 /* If the low bound is specified, "and" the range with the
4846 range for which the original unsigned value will be
4847 positive. */
4849 {
4853 integer_zero_node),
4854 high_positive))
4858 }
4859 else
4860 {
4861 /* Otherwise, "or" the range with the range of the input
4862 that will be interpreted as negative. */
4866 integer_zero_node),
4867 high_positive))
4871 }
4872 }
4880 }
4883 }
4885 /* If EXP is a constant, we can evaluate whether this is true or false. */
4887 {
4894 }
4898 }
4899 \f
4900 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4901 type, TYPE, return an expression to test if EXP is in (or out of, depending
4902 on IN_P) the range. Return 0 if the test couldn't be created. */
4904 tree
4907 {
4910 #ifdef HAVE_canonicalize_funcptr_for_compare
4911 /* Disable this optimization for function pointer expressions
4912 on targets that require function pointer canonicalization. */
4917 #endif
4920 {
4926 }
4944 {
4946 {
4950 }
4952 }
4954 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4956 {
4958 HOST_WIDE_INT hi;
4963 {
4966 }
4967 else
4968 {
4971 }
4974 {
4976 {
4979 etype
4981 else
4984 }
4987 }
4988 }
4990 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4991 This requires wrap-around arithmetics for the type of the expression.
4992 First make sure that arithmetics in this type is valid, then make sure
4993 that it wraps around. */
4999 {
5002 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5003 for the type in question, as we rely on this here. */
5013 else
5015 }
5025 {
5027 {
5034 }
5036 }
5044 }
5045 \f
5046 /* Return the predecessor of VAL in its type, handling the infinite case. */
5048 static tree
5050 {
5056 else
5058 }
5060 /* Return the successor of VAL in its type, handling the infinite case. */
5062 static tree
5064 {
5070 else
5072 }
5074 /* Given two ranges, see if we can merge them into one. Return 1 if we
5075 can, 0 if we can't. Set the output range into the specified parameters. */
5077 bool
5080 {
5084 tree tem;
5094 /* Make range 0 be the range that starts first, or ends last if they
5095 start at the same value. Swap them if it isn't. */
5098 || (lowequal
5101 {
5105 }
5107 /* Now flag two cases, whether the ranges are disjoint or whether the
5108 second range is totally subsumed in the first. Note that the tests
5109 below are simplified by the ones above. */
5115 /* We now have four cases, depending on whether we are including or
5116 excluding the two ranges. */
5118 {
5119 /* If they don't overlap, the result is false. If the second range
5120 is a subset it is the result. Otherwise, the range is from the start
5121 of the second to the end of the first. */
5126 else
5128 }
5131 {
5132 /* If they don't overlap, the result is the first range. If they are
5133 equal, the result is false. If the second range is a subset of the
5134 first, and the ranges begin at the same place, we go from just after
5135 the end of the second range to the end of the first. If the second
5136 range is not a subset of the first, or if it is a subset and both
5137 ranges end at the same place, the range starts at the start of the
5138 first range and ends just before the second range.
5139 Otherwise, we can't describe this as a single range. */
5145 {
5150 {
5151 /* We are in the weird situation where high0 > high1 but
5152 high1 has no successor. Punt. */
5154 }
5155 }
5157 {
5162 {
5163 /* low0 < low1 but low1 has no predecessor. Punt. */
5165 }
5166 }
5167 else
5169 }
5172 {
5173 /* If they don't overlap, the result is the second range. If the second
5174 is a subset of the first, the result is false. Otherwise,
5175 the range starts just after the first range and ends at the
5176 end of the second. */
5181 else
5182 {
5187 {
5188 /* high1 > high0 but high0 has no successor. Punt. */
5190 }
5191 }
5192 }
5194 else
5195 {
5196 /* The case where we are excluding both ranges. Here the complex case
5197 is if they don't overlap. In that case, the only time we have a
5198 range is if they are adjacent. If the second is a subset of the
5199 first, the result is the first. Otherwise, the range to exclude
5200 starts at the beginning of the first range and ends at the end of the
5201 second. */
5203 {
5208 else
5209 {
5210 /* Canonicalize - [min, x] into - [-, x]. */
5213 {
5218 /* FALLTHROUGH */
5231 }
5233 /* Canonicalize - [x, max] into - [x, -]. */
5236 {
5241 /* FALLTHROUGH */
5256 }
5258 /* The ranges might be also adjacent between the maximum and
5259 minimum values of the given type. For
5260 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5261 return + [x + 1, y - 1]. */
5263 {
5270 }
5271 else
5273 }
5274 }
5277 else
5279 }
5283 }
5284 \f
5286 /* Subroutine of fold, looking inside expressions of the form
5287 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5288 of the COND_EXPR. This function is being used also to optimize
5289 A op B ? C : A, by reversing the comparison first.
5291 Return a folded expression whose code is not a COND_EXPR
5292 anymore, or NULL_TREE if no folding opportunity is found. */
5294 static tree
5297 {
5302 tree tem;
5307 /* If we have A op 0 ? A : -A, consider applying the following
5308 transformations:
5310 A == 0? A : -A same as -A
5311 A != 0? A : -A same as A
5312 A >= 0? A : -A same as abs (A)
5313 A > 0? A : -A same as abs (A)
5314 A <= 0? A : -A same as -abs (A)
5315 A < 0? A : -A same as -abs (A)
5317 None of these transformations work for modes with signed
5318 zeros. If A is +/-0, the first two transformations will
5319 change the sign of the result (from +0 to -0, or vice
5320 versa). The last four will fix the sign of the result,
5321 even though the original expressions could be positive or
5322 negative, depending on the sign of A.
5324 Note that all these transformations are correct if A is
5325 NaN, since the two alternatives (A and -A) are also NaNs. */
5332 /* In the case that A is of the form X-Y, '-A' (arg2) may
5333 have already been folded to Y-X, check for that. */
5341 {
5355 /* Fall through. */
5377 }
5379 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5380 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5381 both transformations are correct when A is NaN: A != 0
5382 is then true, and A == 0 is false. */
5386 {
5391 }
5393 /* Try some transformations of A op B ? A : B.
5395 A == B? A : B same as B
5396 A != B? A : B same as A
5397 A >= B? A : B same as max (A, B)
5398 A > B? A : B same as max (B, A)
5399 A <= B? A : B same as min (A, B)
5400 A < B? A : B same as min (B, A)
5402 As above, these transformations don't work in the presence
5403 of signed zeros. For example, if A and B are zeros of
5404 opposite sign, the first two transformations will change
5405 the sign of the result. In the last four, the original
5406 expressions give different results for (A=+0, B=-0) and
5407 (A=-0, B=+0), but the transformed expressions do not.
5409 The first two transformations are correct if either A or B
5410 is a NaN. In the first transformation, the condition will
5411 be false, and B will indeed be chosen. In the case of the
5412 second transformation, the condition A != B will be true,
5413 and A will be chosen.
5415 The conversions to max() and min() are not correct if B is
5416 a number and A is not. The conditions in the original
5417 expressions will be false, so all four give B. The min()
5418 and max() versions would give a NaN instead. */
5421 /* Avoid these transformations if the COND_EXPR may be used
5422 as an lvalue in the C++ front-end. PR c++/19199. */
5423 && (in_gimple_form
5428 {
5433 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5435 {
5439 }
5442 {
5451 /* In C++ a ?: expression can be an lvalue, so put the
5452 operand which will be used if they are equal first
5453 so that we can convert this back to the
5454 corresponding COND_EXPR. */
5456 {
5465 }
5472 {
5481 }
5496 }
5497 }
5499 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5500 we might still be able to simplify this. For example,
5501 if C1 is one less or one more than C2, this might have started
5502 out as a MIN or MAX and been transformed by this function.
5503 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5509 {
5513 /* We can replace A with C1 in this case. */
5518 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5519 MIN_EXPR, to preserve the signedness of the comparison. */
5521 OEP_ONLY_CONST)
5525 OEP_ONLY_CONST))
5526 {
5529 arg2));
5532 }
5536 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5537 as above. */
5539 OEP_ONLY_CONST)
5543 OEP_ONLY_CONST))
5544 {
5547 arg2));
5550 }
5554 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5555 MAX_EXPR, to preserve the signedness of the comparison. */
5557 OEP_ONLY_CONST)
5561 OEP_ONLY_CONST))
5562 {
5565 arg2));
5567 }
5571 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5573 OEP_ONLY_CONST)
5577 OEP_ONLY_CONST))
5578 {
5581 arg2));
5583 }
5589 }
5592 }
5595 \f
5596 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5597 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5598 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5599 false) >= 2)
5600 #endif
5602 /* EXP is some logical combination of boolean tests. See if we can
5603 merge it into some range test. Return the new tree if so. */
5605 static tree
5608 {
5616 tree tem;
5620 /* If this is an OR operation, invert both sides; we will invert
5621 again at the end. */
5625 /* If both expressions are the same, if we can merge the ranges, and we
5626 can build the range test, return it or it inverted. If one of the
5627 ranges is always true or always false, consider it to be the same
5628 expression as the other. */
5636 {
5640 }
5642 /* On machines where the branch cost is expensive, if this is a
5643 short-circuited branch and the underlying object on both sides
5644 is the same, make a non-short-circuit operation. */
5650 {
5651 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5652 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5653 which cases we can't do this. */
5655 {
5661 }
5665 {
5674 {
5677 WARN_STRICT_OVERFLOW_COMPARISON);
5683 }
5684 }
5685 }
5688 }
5689 \f
5690 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5691 bit value. Arrange things so the extra bits will be set to zero if and
5692 only if C is signed-extended to its full width. If MASK is nonzero,
5693 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5695 static tree
5697 {
5700 tree temp;
5705 /* We work by getting just the sign bit into the low-order bit, then
5706 into the high-order bit, then sign-extend. We then XOR that value
5707 with C. */
5711 /* We must use a signed type in order to get an arithmetic right shift.
5712 However, we must also avoid introducing accidental overflows, so that
5713 a subsequent call to integer_zerop will work. Hence we must
5714 do the type conversion here. At this point, the constant is either
5715 zero or one, and the conversion to a signed type can never overflow.
5716 We could get an overflow if this conversion is done anywhere else. */
5726 /* If necessary, convert the type back to match the type of C. */
5732 }
5733 \f
5734 /* Find ways of folding logical expressions of LHS and RHS:
5735 Try to merge two comparisons to the same innermost item.
5736 Look for range tests like "ch >= '0' && ch <= '9'".
5737 Look for combinations of simple terms on machines with expensive branches
5738 and evaluate the RHS unconditionally.
5740 For example, if we have p->a == 2 && p->b == 4 and we can make an
5741 object large enough to span both A and B, we can do this with a comparison
5742 against the object ANDed with the a mask.
5744 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5745 operations to do this with one comparison.
5747 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5748 function and the one above.
5750 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5751 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5753 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5754 two operands.
5756 We return the simplified tree or 0 if no optimization is possible. */
5758 static tree
5761 {
5762 /* If this is the "or" of two comparisons, we can do something if
5763 the comparisons are NE_EXPR. If this is the "and", we can do something
5764 if the comparisons are EQ_EXPR. I.e.,
5765 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5767 WANTED_CODE is this operation code. For single bit fields, we can
5768 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5769 comparison for one-bit fields. */
5791 /* Start by getting the comparison codes. Fail if anything is volatile.
5792 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5793 it were surrounded with a NE_EXPR. */
5802 {
5806 }
5809 {
5813 }
5824 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5827 {
5828 tree result;
5831 {
5836 }
5839 {
5845 }
5846 }
5851 /* If the RHS can be evaluated unconditionally and its operands are
5852 simple, it wins to evaluate the RHS unconditionally on machines
5853 with expensive branches. In this case, this isn't a comparison
5854 that can be merged. Avoid doing this if the RHS is a floating-point
5855 comparison since those can trap. */
5862 {
5863 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5869 {
5875 }
5877 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5883 {
5889 }
5892 {
5894 {
5897 }
5899 }
5900 }
5902 /* See if the comparisons can be merged. Then get all the parameters for
5903 each side. */
5927 /* It must be true that the inner operation on the lhs of each
5928 comparison must be the same if we are to be able to do anything.
5929 Then see if we have constants. If not, the same must be true for
5930 the rhs's. */
5941 else
5944 /* If either comparison code is not correct for our logical operation,
5945 fail. However, we can convert a one-bit comparison against zero into
5946 the opposite comparison against that bit being set in the field. */
5950 {
5952 {
5953 /* Make the left operand unsigned, since we are only interested
5954 in the value of one bit. Otherwise we are doing the wrong
5955 thing below. */
5958 }
5959 else
5961 }
5963 /* This is analogous to the code for l_const above. */
5965 {
5967 {
5970 }
5971 else
5973 }
5975 /* See if we can find a mode that contains both fields being compared on
5976 the left. If we can't, fail. Otherwise, update all constants and masks
5977 to be relative to a field of that size. */
5982 volatilep);
5992 {
5995 }
6003 {
6011 {
6015 }
6016 }
6018 {
6026 {
6030 }
6031 }
6033 /* If the right sides are not constant, do the same for it. Also,
6034 disallow this optimization if a size or signedness mismatch occurs
6035 between the left and right sides. */
6037 {
6040 /* Make sure the two fields on the right
6041 correspond to the left without being swapped. */
6049 volatilep);
6059 {
6062 }
6071 /* Make a mask that corresponds to both fields being compared.
6072 Do this for both items being compared. If the operands are the
6073 same size and the bits being compared are in the same position
6074 then we can do this by masking both and comparing the masked
6075 results. */
6079 {
6092 }
6094 /* There is still another way we can do something: If both pairs of
6095 fields being compared are adjacent, we may be able to make a wider
6096 field containing them both.
6098 Note that we still must mask the lhs/rhs expressions. Furthermore,
6099 the mask must be shifted to account for the shift done by
6100 make_bit_field_ref. */
6105 {
6106 tree type;
6120 /* Convert to the smaller type before masking out unwanted bits. */
6123 {
6125 {
6129 }
6131 {
6135 }
6136 }
6146 }
6149 }
6151 /* Handle the case of comparisons with constants. If there is something in
6152 common between the masks, those bits of the constants must be the same.
6153 If not, the condition is always false. Test for this to avoid generating
6154 incorrect code below. */
6159 {
6161 {
6164 }
6165 else
6166 {
6169 }
6170 }
6172 /* Construct the expression we will return. First get the component
6173 reference we will make. Unless the mask is all ones the width of
6174 that field, perform the mask operation. Then compare with the
6175 merged constant. */
6181 {
6184 }
6189 fold_truthop_exit:
6192 }
6193 \f
6194 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
6195 constant. */
6197 static tree
6200 {
6203 tree comp_const;
6204 tree minmax_const;
6206 tree inner;
6217 /* If something does not permit us to optimize, return the original tree. */
6225 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6226 and GT_EXPR, doing the rest with recursive calls using logical
6227 simplifications. */
6229 {
6231 {
6232 tree tem
6239 }
6242 return
6244 optimize_minmax_comparison
6246 optimize_minmax_comparison
6251 /* MAX (X, 0) == 0 -> X <= 0 */
6255 /* MAX (X, 0) == 5 -> X == 5 */
6259 /* MAX (X, 0) == -1 -> false */
6263 /* MIN (X, 0) == 0 -> X >= 0 */
6267 /* MIN (X, 0) == 5 -> false */
6270 else
6271 /* MIN (X, 0) == -1 -> X == -1 */
6276 /* MAX (X, 0) > 0 -> X > 0
6277 MAX (X, 0) > 5 -> X > 5 */
6281 /* MAX (X, 0) > -1 -> true */
6285 /* MIN (X, 0) > 0 -> false
6286 MIN (X, 0) > 5 -> false */
6289 else
6290 /* MIN (X, 0) > -1 -> X > -1 */
6295 }
6296 }
6297 \f
6298 /* T is an integer expression that is being multiplied, divided, or taken a
6299 modulus (CODE says which and what kind of divide or modulus) by a
6300 constant C. See if we can eliminate that operation by folding it with
6301 other operations already in T. WIDE_TYPE, if non-null, is a type that
6302 should be used for the computation if wider than our type.
6304 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6305 (X * 2) + (Y * 4). We must, however, be assured that either the original
6306 expression would not overflow or that overflow is undefined for the type
6307 in the language in question.
6309 If we return a non-null expression, it is an equivalent form of the
6310 original computation, but need not be in the original type.
6312 We set *STRICT_OVERFLOW_P to true if the return values depends on
6313 signed overflow being undefined. Otherwise we do not change
6314 *STRICT_OVERFLOW_P. */
6316 static tree
6319 {
6320 /* To avoid exponential search depth, refuse to allow recursion past
6321 three levels. Beyond that (1) it's highly unlikely that we'll find
6322 something interesting and (2) we've probably processed it before
6323 when we built the inner expression. */
6326 tree ret;
6331 depth++;
6333 depth--;
6336 }
6338 static tree
6341 {
6352 /* Don't deal with constants of zero here; they confuse the code below. */
6362 /* Note that we need not handle conditional operations here since fold
6363 already handles those cases. So just do arithmetic here. */
6365 {
6367 /* For a constant, we can always simplify if we are a multiply
6368 or (for divide and modulus) if it is a multiple of our constant. */
6376 /* If op0 is an expression ... */
6382 /* ... and has wrapping overflow, and its type is smaller
6383 than ctype, then we cannot pass through as widening. */
6389 /* ... or this is a truncation (t is narrower than op0),
6390 then we cannot pass through this narrowing. */
6393 /* ... or signedness changes for division or modulus,
6394 then we cannot pass through this conversion. */
6398 /* ... or has undefined overflow while the converted to
6399 type has not, we cannot do the operation in the inner type
6400 as that would introduce undefined overflow. */
6405 /* Pass the constant down and see if we can make a simplification. If
6406 we can, replace this expression with the inner simplification for
6407 possible later conversion to our or some other type. */
6412 code == MULT_EXPR
6414 strict_overflow_p))))
6419 /* If widening the type changes it from signed to unsigned, then we
6420 must avoid building ABS_EXPR itself as unsigned. */
6422 {
6426 {
6429 }
6431 }
6432 /* If the constant is negative, we cannot simplify this. */
6435 /* FALLTHROUGH */
6443 /* If widening the type changes the signedness, then we can't perform
6444 this optimization as that changes the result. */
6448 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6454 {
6461 }
6465 /* If the second operand is constant, this is a multiplication
6466 or floor division, by a power of two, so we can treat it that
6467 way unless the multiplier or divisor overflows. Signed
6468 left-shift overflow is implementation-defined rather than
6469 undefined in C90, so do not convert signed left shift into
6470 multiplication. */
6473 /* const_binop may not detect overflow correctly,
6474 so check for it explicitly here. */
6479 size_one_node,
6484 ctype,
6486 t1),
6491 /* See if we can eliminate the operation on both sides. If we can, we
6492 can return a new PLUS or MINUS. If we can't, the only remaining
6493 cases where we can do anything are if the second operand is a
6494 constant. */
6500 /* If not multiplication, we can only do this if both operands
6501 are divisible by c. */
6504 {
6509 }
6511 /* If this was a subtraction, negate OP1 and set it to be an addition.
6512 This simplifies the logic below. */
6514 {
6516 /* If OP1 was not easily negatable, the constant may be OP0. */
6518 {
6525 }
6526 }
6531 /* If either OP1 or C are negative, this optimization is not safe for
6532 some of the division and remainder types while for others we need
6533 to change the code. */
6535 {
6543 }
6545 /* If it's a multiply or a division/modulus operation of a multiple
6546 of our constant, do the operation and verify it doesn't overflow. */
6549 {
6552 /* We allow the constant to overflow with wrapping semantics. */
6556 }
6557 else
6560 /* If we have an unsigned type is not a sizetype, we cannot widen
6561 the operation since it will change the result if the original
6562 computation overflowed. */
6568 /* If we were able to eliminate our operation from the first side,
6569 apply our operation to the second side and reform the PLUS. */
6573 /* The last case is if we are a multiply. In that case, we can
6574 apply the distributive law to commute the multiply and addition
6575 if the multiplication of the constants doesn't overflow. */
6581 op1);
6586 /* We have a special case here if we are doing something like
6587 (C * 8) % 4 since we know that's zero. */
6590 /* If the multiplication can overflow we cannot optimize this.
6591 ??? Until we can properly mark individual operations as
6592 not overflowing we need to treat sizetype special here as
6593 stor-layout relies on this opimization to make
6594 DECL_FIELD_BIT_OFFSET always a constant. */
6600 {
6603 }
6605 /* ... fall through ... */
6609 /* If we can extract our operation from the LHS, do so and return a
6610 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6611 do something only if the second operand is a constant. */
6625 /* If these are the same operation types, we can associate them
6626 assuming no overflow. */
6639 /* If these operations "cancel" each other, we have the main
6640 optimizations of this pass, which occur when either constant is a
6641 multiple of the other, in which case we replace this with either an
6642 operation or CODE or TCODE.
6644 If we have an unsigned type that is not a sizetype, we cannot do
6645 this since it will change the result if the original computation
6646 overflowed. */
6654 {
6656 {
6663 }
6665 {
6672 }
6673 }
6678 }
6681 }
6682 \f
6683 /* Return a node which has the indicated constant VALUE (either 0 or
6684 1), and is of the indicated TYPE. */
6686 tree
6688 {
6693 else
6695 }
6698 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6699 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6700 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6701 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6702 COND is the first argument to CODE; otherwise (as in the example
6703 given here), it is the second argument. TYPE is the type of the
6704 original expression. Return NULL_TREE if no simplification is
6705 possible. */
6707 static tree
6712 {
6719 /* This transformation is only worthwhile if we don't have to wrap
6720 arg in a SAVE_EXPR, and the operation can be simplified on at least
6721 one of the branches once its pushed inside the COND_EXPR. */
6726 {
6730 /* If this operand throws an expression, then it does not make
6731 sense to try to perform a logical or arithmetic operation
6732 involving it. */
6737 }
6738 else
6739 {
6744 }
6748 {
6752 else
6754 }
6756 {
6760 else
6762 }
6766 }
6768 \f
6769 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6771 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6772 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6773 ADDEND is the same as X.
6775 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6776 and finite. The problematic cases are when X is zero, and its mode
6777 has signed zeros. In the case of rounding towards -infinity,
6778 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6779 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6781 bool
6783 {
6787 /* Don't allow the fold with -fsignaling-nans. */
6791 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6795 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6800 /* The mode has signed zeros, and we have to honor their sign.
6801 In this situation, there is only one case we can return true for.
6802 X - 0 is the same as X unless rounding towards -infinity is
6803 supported. */
6805 }
6807 /* Subroutine of fold() that checks comparisons of built-in math
6808 functions against real constants.
6810 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6811 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6812 is the type of the result and ARG0 and ARG1 are the operands of the
6813 comparison. ARG1 must be a TREE_REAL_CST.
6815 The function returns the constant folded tree if a simplification
6816 can be made, and NULL_TREE otherwise. */
6818 static tree
6822 {
6823 REAL_VALUE_TYPE c;
6826 {
6832 {
6833 /* sqrt(x) < y is always false, if y is negative. */
6837 /* sqrt(x) > y is always true, if y is negative and we
6838 don't care about NaNs, i.e. negative values of x. */
6842 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6845 }
6847 {
6848 REAL_VALUE_TYPE c2;
6854 {
6855 /* sqrt(x) > y is x == +Inf, when y is very large. */
6860 /* sqrt(x) > y is always false, when y is very large
6861 and we don't care about infinities. */
6863 }
6865 /* sqrt(x) > c is the same as x > c*c. */
6868 }
6870 {
6871 REAL_VALUE_TYPE c2;
6877 {
6878 /* sqrt(x) < y is always true, when y is a very large
6879 value and we don't care about NaNs or Infinities. */
6883 /* sqrt(x) < y is x != +Inf when y is very large and we
6884 don't care about NaNs. */
6889 /* sqrt(x) < y is x >= 0 when y is very large and we
6890 don't care about Infinities. */
6895 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6904 dconst0)),
6907 c2)));
6908 }
6910 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6915 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6918 {
6923 dconst0)),
6926 c2)));
6927 }
6928 }
6929 }
6932 }
6934 /* Subroutine of fold() that optimizes comparisons against Infinities,
6935 either +Inf or -Inf.
6937 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6938 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6939 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6941 The function returns the constant folded tree if a simplification
6942 can be made, and NULL_TREE otherwise. */
6944 static tree
6947 {
6949 REAL_VALUE_TYPE max;
6950 tree temp;
6955 /* For negative infinity swap the sense of the comparison. */
6961 {
6963 /* x > +Inf is always false, if with ignore sNANs. */
6969 /* x <= +Inf is always true, if we don't case about NaNs. */
6973 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6976 {
6979 }
6984 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6990 /* x < +Inf is always equal to x <= DBL_MAX. */
6996 /* x != +Inf is always equal to !(x > DBL_MAX). */
7008 }
7011 }
7013 /* Subroutine of fold() that optimizes comparisons of a division by
7014 a nonzero integer constant against an integer constant, i.e.
7015 X/C1 op C2.
7017 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7018 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
7019 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
7021 The function returns the constant folded tree if a simplification
7022 can be made, and NULL_TREE otherwise. */
7024 static tree
7027 {
7032 HOST_WIDE_INT hpart;
7037 /* We have to do this the hard way to detect unsigned overflow.
7038 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
7049 {
7054 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
7062 }
7064 {
7068 {
7087 }
7088 }
7089 else
7090 {
7091 /* A negative divisor reverses the relational operators. */
7097 {
7116 }
7117 }
7120 {
7141 {
7144 }
7149 {
7152 }
7157 {
7160 }
7165 {
7168 }
7173 }
7176 }
7179 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7180 equality/inequality test, then return a simplified form of the test
7181 using a sign testing. Otherwise return NULL. TYPE is the desired
7182 result type. */
7184 static tree
7187 tree result_type)
7188 {
7189 /* If this is testing a single bit, we can optimize the test. */
7193 {
7194 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7195 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7199 /* This is only a win if casting to a signed type is cheap,
7200 i.e. when arg00's type is not a partial mode. */
7203 {
7206 result_type,
7209 }
7210 }
7213 }
7215 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7216 equality/inequality test, then return a simplified form of
7217 the test using shifts and logical operations. Otherwise return
7218 NULL. TYPE is the desired result type. */
7220 tree
7223 {
7224 /* If this is testing a single bit, we can optimize the test. */
7228 {
7237 /* First, see if we can fold the single bit test into a sign-bit
7238 test. */
7240 result_type);
7244 /* Otherwise we have (A & C) != 0 where C is a single bit,
7245 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7246 Similarly for (A & C) == 0. */
7248 /* If INNER is a right shift of a constant and it plus BITNUM does
7249 not overflow, adjust BITNUM and INNER. */
7256 {
7259 }
7261 /* If we are going to be able to omit the AND below, we must do our
7262 operations as unsigned. If we must use the AND, we have a choice.
7263 Normally unsigned is faster, but for some machines signed is. */
7264 #ifdef LOAD_EXTEND_OP
7267 #else
7269 #endif
7285 /* Put the AND last so it can combine with more things. */
7288 /* Make sure to return the proper type. */
7292 }
7294 }
7296 /* Check whether we are allowed to reorder operands arg0 and arg1,
7297 such that the evaluation of arg1 occurs before arg0. */
7299 static bool
7301 {
7308 }
7310 /* Test whether it is preferable two swap two operands, ARG0 and
7311 ARG1, for example because ARG0 is an integer constant and ARG1
7312 isn't. If REORDER is true, only recommend swapping if we can
7313 evaluate the operands in reverse order. */
7315 bool
7317 {
7353 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7354 for commutative and comparison operators. Ensuring a canonical
7355 form allows the optimizers to find additional redundancies without
7356 having to explicitly check for both orderings. */
7362 /* Put SSA_NAMEs last. */
7368 /* Put variables last. */
7375 }
7377 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7378 ARG0 is extended to a wider type. */
7380 static tree
7383 {
7385 tree arg1_unw;
7394 #ifdef HAVE_canonicalize_funcptr_for_compare
7395 /* Disable this optimization if we're casting a function pointer
7396 type on targets that require function pointer canonicalization. */
7401 #endif
7408 /* If possible, express the comparison in the shorter mode. */
7428 /* If we are comparing with the integer that does not fit into the range
7429 of the shorter type, the result is known. */
7440 {
7467 }
7470 }
7472 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7473 ARG0 just the signedness is changed. */
7475 static tree
7478 {
7479 tree arg0_inner;
7489 #ifdef HAVE_canonicalize_funcptr_for_compare
7490 /* Disable this optimization if we're casting a function pointer
7491 type on targets that require function pointer canonicalization. */
7496 #endif
7516 else
7520 }
7522 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7523 step of the array. Reconstructs s and delta in the case of s *
7524 delta being an integer constant (and thus already folded). ADDR is
7525 the address. MULT is the multiplicative expression. If the
7526 function succeeds, the new address expression is returned.
7527 Otherwise NULL_TREE is returned. LOC is the location of the
7528 resulting expression. */
7530 static tree
7532 {
7536 tree itype;
7539 /* Strip the nops that might be added when converting op1 to sizetype. */
7542 /* Canonicalize op1 into a possibly non-constant delta
7543 and an INTEGER_CST s. */
7545 {
7552 {
7555 }
7557 {
7560 }
7561 else
7563 }
7565 {
7568 }
7569 else
7570 {
7571 /* Simulate we are delta * 1. */
7574 }
7577 {
7579 {
7580 tree domain;
7582 /* Remember if this was a multi-dimensional array. */
7596 {
7599 }
7600 else
7601 {
7602 /* Try if delta is a multiple of step. */
7607 }
7609 /* Only fold here if we can verify we do not overflow one
7610 dimension of a multi-dimensional array. */
7612 {
7613 tree tmp;
7628 }
7631 }
7632 else
7637 }
7639 /* We found the suitable array reference. So copy everything up to it,
7640 and replace the index. */
7648 {
7652 }
7660 }
7663 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7664 means A >= Y && A != MAX, but in this case we know that
7665 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7667 static tree
7669 {
7676 else
7685 {
7688 }
7690 {
7693 }
7694 else
7701 {
7702 /* Convert the pointer types into integer before taking the difference. */
7706 }
7707 else
7714 }
7716 /* Fold a sum or difference of at least one multiplication.
7717 Returns the folded tree or NULL if no simplification could be made. */
7719 static tree
7722 {
7726 /* (A * C) +- (B * C) -> (A+-B) * C.
7727 (A * C) +- A -> A * (C+-1).
7728 We are most concerned about the case where C is a constant,
7729 but other combinations show up during loop reduction. Since
7730 it is not difficult, try all four possibilities. */
7733 {
7736 }
7738 {
7741 }
7742 else
7743 {
7744 /* We cannot generate constant 1 for fract. */
7749 }
7751 {
7754 }
7756 {
7758 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7759 the purpose of this canonicalization. */
7763 {
7766 }
7767 else
7769 }
7770 else
7771 {
7772 /* We cannot generate constant 1 for fract. */
7777 }
7789 /* No identical multiplicands; see if we can find a common
7790 power-of-two factor in non-power-of-two multiplies. This
7791 can help in multi-dimensional array access. */
7794 {
7797 tree maybe_same;
7801 /* Move min of absolute values to int11. */
7804 {
7809 }
7810 else
7814 /* The remainder should not be a constant, otherwise we
7815 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7816 increased the number of multiplications necessary. */
7818 {
7826 }
7827 }
7837 }
7839 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7840 specified by EXPR into the buffer PTR of length LEN bytes.
7841 Return the number of bytes placed in the buffer, or zero
7842 upon failure. */
7844 static int
7846 {
7857 {
7861 else
7866 {
7873 else
7875 }
7876 else
7879 }
7881 }
7884 /* Subroutine of native_encode_expr. Encode the REAL_CST
7885 specified by EXPR into the buffer PTR of length LEN bytes.
7886 Return the number of bytes placed in the buffer, or zero
7887 upon failure. */
7889 static int
7891 {
7897 /* There are always 32 bits in each long, no matter the size of
7898 the hosts long. We handle floating point representations with
7899 up to 192 bits. */
7910 {
7915 {
7922 else
7924 }
7925 else
7928 }
7930 }
7932 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7933 specified by EXPR into the buffer PTR of length LEN bytes.
7934 Return the number of bytes placed in the buffer, or zero
7935 upon failure. */
7937 static int
7939 {
7941 tree part;
7952 }
7955 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7956 specified by EXPR into the buffer PTR of length LEN bytes.
7957 Return the number of bytes placed in the buffer, or zero
7958 upon failure. */
7960 static int
7962 {
7972 {
7974 {
7977 }
7978 else
7982 {
7985 }
7986 else
7987 {
7991 }
7993 }
7995 }
7998 /* Subroutine of native_encode_expr. Encode the STRING_CST
7999 specified by EXPR into the buffer PTR of length LEN bytes.
8000 Return the number of bytes placed in the buffer, or zero
8001 upon failure. */
8003 static int
8005 {
8007 HOST_WIDE_INT total_bytes;
8018 {
8022 }
8023 else
8026 }
8029 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
8030 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
8031 buffer PTR of length LEN bytes. Return the number of bytes
8032 placed in the buffer, or zero upon failure. */
8034 int
8036 {
8038 {
8056 }
8057 }
8060 /* Subroutine of native_interpret_expr. Interpret the contents of
8061 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8062 If the buffer cannot be interpreted, return NULL_TREE. */
8064 static tree
8066 {
8080 {
8083 {
8090 else
8092 }
8093 else
8099 else
8102 }
8105 }
8108 /* Subroutine of native_interpret_expr. Interpret the contents of
8109 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8110 If the buffer cannot be interpreted, return NULL_TREE. */
8112 static tree
8114 {
8119 /* There are always 32 bits in each long, no matter the size of
8120 the hosts long. We handle floating point representations with
8121 up to 192 bits. */
8122 REAL_VALUE_TYPE r;
8133 {
8136 {
8143 else
8145 }
8146 else
8151 }
8155 }
8158 /* Subroutine of native_interpret_expr. Interpret the contents of
8159 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8160 If the buffer cannot be interpreted, return NULL_TREE. */
8162 static tree
8164 {
8179 }
8182 /* Subroutine of native_interpret_expr. Interpret the contents of
8183 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8184 If the buffer cannot be interpreted, return NULL_TREE. */
8186 static tree
8188 {
8200 {
8205 }
8207 }
8210 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8211 the buffer PTR of length LEN as a constant of type TYPE. For
8212 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8213 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8214 return NULL_TREE. */
8216 tree
8218 {
8220 {
8237 }
8238 }
8241 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
8242 TYPE at compile-time. If we're unable to perform the conversion
8243 return NULL_TREE. */
8245 static tree
8247 {
8248 /* We support up to 512-bit values (for V8DFmode). */
8252 /* Check that the host and target are sane. */
8261 }
8263 /* Build an expression for the address of T. Folds away INDIRECT_REF
8264 to avoid confusing the gimplify process. */
8266 tree
8268 {
8269 /* The size of the object is not relevant when talking about its address. */
8273 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8276 {
8280 {
8283 }
8284 }
8286 {
8291 }
8292 else
8293 {
8296 }
8299 }
8301 /* Build an expression for the address of T. */
8303 tree
8305 {
8309 }
8311 /* Fold a unary expression of code CODE and type TYPE with operand
8312 OP0. Return the folded expression if folding is successful.
8313 Otherwise, return NULL_TREE. */
8315 tree
8317 {
8318 tree tem;
8319 tree arg0;
8327 {
8330 {
8331 /* Don't use STRIP_NOPS, because signedness of argument type
8332 matters. */
8334 }
8335 else
8336 {
8337 /* Strip any conversions that don't change the mode. This
8338 is safe for every expression, except for a comparison
8339 expression because its signedness is derived from its
8340 operands.
8342 Note that this is done as an internal manipulation within
8343 the constant folder, in order to find the simplest
8344 representation of the arguments so that their form can be
8345 studied. In any cases, the appropriate type conversions
8346 should be put back in the tree that will get out of the
8347 constant folder. */
8349 }
8350 }
8353 {
8360 {
8374 /* If this was a conversion, and all we did was to move into
8375 inside the COND_EXPR, bring it back out. But leave it if
8376 it is a conversion from integer to integer and the
8377 result precision is no wider than a word since such a
8378 conversion is cheap and may be optimized away by combine,
8379 while it couldn't if it were outside the COND_EXPR. Then return
8380 so we don't get into an infinite recursion loop taking the
8381 conversion out and then back in. */
8393 && (INTEGRAL_TYPE_P
8397 {
8406 }
8408 }
8410 {
8412 {
8416 }
8420 integer_one_node),
8422 integer_zero_node));
8423 }
8424 }
8427 {
8429 /* Re-association barriers around constants and other re-association
8430 barriers can be removed. */
8436 CASE_CONVERT:
8442 /* If we have (type) (a CMP b) and type is an integral type, return
8443 new expression involving the new type. */
8448 /* Handle cases of two conversions in a row. */
8450 {
8472 /* In addition to the cases of two conversions in a row
8473 handled below, if we are converting something to its own
8474 type via an object of identical or wider precision, neither
8475 conversion is needed. */
8482 /* Likewise, if the intermediate and initial types are either both
8483 float or both integer, we don't need the middle conversion if the
8484 former is wider than the latter and doesn't change the signedness
8485 (for integers). Avoid this if the final type is a pointer since
8486 then we sometimes need the middle conversion. Likewise if the
8487 final type has a precision not equal to the size of its mode. */
8496 && ! final_ptr
8500 /* If we have a sign-extension of a zero-extended value, we can
8501 replace that by a single zero-extension. */
8507 /* Two conversions in a row are not needed unless:
8508 - some conversion is floating-point (overstrict for now), or
8509 - some conversion is a vector (overstrict for now), or
8510 - the intermediate type is narrower than both initial and
8511 final, or
8512 - the intermediate type and innermost type differ in signedness,
8513 and the outermost type is wider than the intermediate, or
8514 - the initial type is a pointer type and the precisions of the
8515 intermediate and final types differ, or
8516 - the final type is a pointer type and the precisions of the
8517 initial and intermediate types differ. */
8531 }
8533 /* Handle (T *)&A.B.C for A being of type T and B and C
8534 living at offset zero. This occurs frequently in
8535 C++ upcasting and then accessing the base. */
8539 {
8541 tree offset;
8547 /* If the reference was to a (constant) zero offset, we can use
8548 the address of the base if it has the same base type
8549 as the result type. */
8555 }
8559 /* Detect assigning a bitfield. */
8561 && DECL_BIT_FIELD
8563 {
8564 /* Don't leave an assignment inside a conversion
8565 unless assigning a bitfield. */
8567 /* First do the assignment, then return converted constant. */
8573 }
8575 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8576 constants (if x has signed type, the sign bit cannot be set
8577 in c). This folds extension into the BIT_AND_EXPR.
8578 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8579 very likely don't have maximal range for their precision and this
8580 transformation effectively doesn't preserve non-maximal ranges. */
8584 {
8595 <= HOST_BITS_PER_WIDE_INT
8597 {
8604 #ifdef LOAD_EXTEND_OP
8606 && !flag_syntax_only
8609 {
8613 }
8614 #endif
8615 }
8617 {
8623 }
8624 }
8626 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8627 when one of the new casts will fold away. Conservatively we assume
8628 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8634 {
8642 }
8644 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8645 of the same precision, and X is an integer type not narrower than
8646 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8652 {
8658 }
8660 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8661 type of X and Y (integer types only). */
8666 {
8667 /* Be careful not to introduce new overflows. */
8668 tree mult_type;
8671 else
8675 {
8682 }
8683 }
8704 /* For integral conversions with the same precision or pointer
8705 conversions use a NOP_EXPR instead. */
8713 /* Strip inner integral conversions that do not change the precision. */
8737 /* Convert fabs((double)float) into (double)fabsf(float). */
8740 {
8746 targ0));
8747 }
8748 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8754 /* Strip sign ops from argument. */
8756 {
8761 }
8768 {
8774 }
8776 {
8781 }
8791 /* Convert ~ (-A) to A - 1. */
8796 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8805 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8820 /* Perform BIT_NOT_EXPR on each element individually. */
8822 {
8827 {
8829 {
8835 }
8836 else
8839 }
8842 }
8847 /* The argument to invert_truthvalue must have Boolean type. */
8851 /* Note that the operand of this must be an int
8852 and its values must be 0 or 1.
8853 ("true" is a fixed value perhaps depending on the language,
8854 but we don't handle values other than 1 correctly yet.) */
8869 {
8877 }
8879 {
8884 }
8886 {
8890 {
8899 }
8900 }
8912 {
8920 }
8922 {
8926 }
8928 {
8932 {
8941 }
8942 }
8948 }
8951 /* If the operation was a conversion do _not_ mark a resulting constant
8952 with TREE_OVERFLOW if the original constant was not. These conversions
8953 have implementation defined behavior and retaining the TREE_OVERFLOW
8954 flag here would confuse later passes such as VRP. */
8955 tree
8958 {
8967 }
8969 /* Fold a binary expression of code CODE and type TYPE with operands
8970 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8971 Return the folded expression if folding is successful. Otherwise,
8972 return NULL_TREE. */
8974 static tree
8976 {
8983 else
8986 /* MIN (MAX (a, b), b) == b. */
8991 /* MIN (MAX (b, a), b) == b. */
8997 /* MIN (a, MAX (a, b)) == a. */
9003 /* MIN (a, MAX (b, a)) == a. */
9010 }
9012 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9013 by changing CODE to reduce the magnitude of constants involved in
9014 ARG0 of the comparison.
9015 Returns a canonicalized comparison tree if a simplification was
9016 possible, otherwise returns NULL_TREE.
9017 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9018 valid if signed overflow is undefined. */
9020 static tree
9024 {
9030 /* Match A +- CST code arg1 and CST code arg1. We can change the
9031 first form only if overflow is undefined. */
9033 /* In principle pointers also have undefined overflow behavior,
9034 but that causes problems elsewhere. */
9042 /* Identify the constant in arg0 and its sign. */
9045 else
9049 /* Overflowed constants and zero will cause problems. */
9054 /* See if we can reduce the magnitude of the constant in
9055 arg0 by changing the comparison code. */
9057 {
9058 /* CST <= arg1 -> CST-1 < arg1. */
9061 /* -CST < arg1 -> -CST-1 <= arg1. */
9064 /* CST > arg1 -> CST-1 >= arg1. */
9067 /* -CST >= arg1 -> -CST-1 > arg1. */
9070 else
9072 /* arg1 code' CST' might be more canonical. */
9074 }
9075 else
9076 {
9077 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9081 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9085 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9089 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9093 else
9096 }
9098 /* Now build the constant reduced in magnitude. But not if that
9099 would produce one outside of its types range. */
9107 /* We cannot swap the comparison here as that would cause us to
9108 endlessly recurse. */
9116 /* If swapping might yield to a more canonical form, do so. */
9119 else
9121 }
9123 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9124 overflow further. Try to decrease the magnitude of constants involved
9125 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9126 and put sole constants at the second argument position.
9127 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9129 static tree
9132 {
9133 tree t;
9138 /* Try canonicalization by simplifying arg0. */
9143 {
9147 }
9149 /* Try canonicalization by simplifying arg1 using the swapped
9150 comparison. */
9158 }
9160 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9161 space. This is used to avoid issuing overflow warnings for
9162 expressions like &p->x which can not wrap. */
9164 static bool
9166 {
9177 {
9180 }
9183 else
9184 {
9187 }
9202 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9203 array. */
9205 {
9206 HOST_WIDE_INT base_size;
9211 }
9214 }
9216 /* Subroutine of fold_binary. This routine performs all of the
9217 transformations that are common to the equality/inequality
9218 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9219 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9220 fold_binary should call fold_binary. Fold a comparison with
9221 tree code CODE and type TYPE with operands OP0 and OP1. Return
9222 the folded comparison or NULL_TREE. */
9224 static tree
9227 {
9240 /* If one arg is a real or integer constant, put it last. */
9244 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
9251 {
9255 tree lhs;
9262 /* If the constant operation overflowed this can be
9263 simplified as a comparison against INT_MAX/INT_MIN. */
9266 {
9270 /* Get the sign of the constant on the lhs if the
9271 operation were VARIABLE + CONST1. */
9275 /* The sign of the constant determines if we overflowed
9276 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9277 Canonicalize to the INT_MIN overflow by swapping the comparison
9278 if necessary. */
9282 /* We now can look at the canonicalized case
9283 VARIABLE + 1 CODE2 INT_MIN
9284 and decide on the result. */
9293 }
9298 {
9300 "when changing X +- C1 cmp C2 to "
9302 WARN_STRICT_OVERFLOW_COMPARISON);
9304 }
9305 }
9307 /* For comparisons of pointers we can decompose it to a compile time
9308 comparison of the base objects and the offsets into the object.
9309 This requires at least one operand being an ADDR_EXPR or a
9310 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9316 {
9323 /* Get base and offset for the access. Strip ADDR_EXPR for
9324 get_inner_reference, but put it back by stripping INDIRECT_REF
9325 off the base object if possible. indirect_baseN will be true
9326 if baseN is not an address but refers to the object itself. */
9329 {
9335 else
9337 }
9339 {
9342 }
9346 {
9352 else
9354 }
9356 {
9359 }
9361 /* If we have equivalent bases we might be able to simplify. */
9364 {
9365 /* We can fold this expression to a constant if the non-constant
9366 offset parts are equal. */
9374 {
9381 "occur when comparing P +- C1 with "
9383 WARN_STRICT_OVERFLOW_CONDITIONAL);
9386 {
9400 }
9401 }
9402 /* We can simplify the comparison to a comparison of the variable
9403 offset parts if the constant offset parts are equal.
9404 Be careful to use signed size type here because otherwise we
9405 mess with array offsets in the wrong way. This is possible
9406 because pointer arithmetic is restricted to retain within an
9407 object and overflow on pointer differences is undefined as of
9408 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9412 {
9413 tree signed_size_type_node;
9416 /* By converting to signed size type we cover middle-end pointer
9417 arithmetic which operates on unsigned pointer types of size
9418 type size and ARRAY_REF offsets which are properly sign or
9419 zero extended from their type in case it is narrower than
9420 size type. */
9423 else
9425 offset0);
9428 else
9430 offset1);
9437 "occur when comparing P +- C1 with "
9439 WARN_STRICT_OVERFLOW_COMPARISON);
9442 }
9443 }
9444 /* For non-equal bases we can simplify if they are addresses
9445 of local binding decls or constants. */
9447 /* We know that !operand_equal_p (base0, base1, 0)
9448 because the if condition was false. But make
9449 sure two decls are not the same. */
9463 {
9470 }
9471 /* For equal offsets we can simplify to a comparison of the
9472 base addresses. */
9474 && (indirect_base0
9476 && (indirect_base1
9481 {
9487 }
9488 }
9490 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9491 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9492 the resulting offset is smaller in absolute value than the
9493 original one. */
9501 {
9506 tree cst;
9508 "occur when combining constants around "
9511 /* Put the constant on the side where it doesn't overflow and is
9512 of lower absolute value than before. */
9518 {
9521 variable1,
9525 }
9532 {
9537 variable2);
9538 }
9539 }
9541 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9542 signed arithmetic case. That form is created by the compiler
9543 often enough for folding it to be of value. One example is in
9544 computing loop trip counts after Operator Strength Reduction. */
9550 {
9559 "eliminating multiplication in comparison "
9561 WARN_STRICT_OVERFLOW_COMPARISON);
9563 /* If const1 is negative we swap the sense of the comparison. */
9568 }
9575 {
9583 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9589 /* (-a) CMP (-b) -> b CMP a */
9596 {
9597 REAL_VALUE_TYPE cst;
9600 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9607 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9608 /* a CMP (-0) -> a CMP 0 */
9613 /* x != NaN is always true, other ops are always false. */
9616 {
9619 }
9621 /* Fold comparisons against infinity. */
9624 {
9628 }
9629 }
9631 /* If this is a comparison of a real constant with a PLUS_EXPR
9632 or a MINUS_EXPR of a real constant, we can convert it into a
9633 comparison with a revised real constant as long as no overflow
9634 occurs when unsafe_math_optimizations are enabled. */
9646 /* Likewise, we can simplify a comparison of a real constant with
9647 a MINUS_EXPR whose first operand is also a real constant, i.e.
9648 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9649 floating-point types only if -fassociative-math is set. */
9660 /* Fold comparisons against built-in math functions. */
9662 && flag_unsafe_math_optimizations
9664 {
9668 {
9672 }
9673 }
9674 }
9678 {
9679 /* If we are widening one operand of an integer comparison,
9680 see if the other operand is similarly being widened. Perhaps we
9681 can do the comparison in the narrower type. */
9686 /* Or if we are changing signedness. */
9690 }
9692 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9693 constant, we can simplify it. */
9698 {
9702 }
9704 /* Simplify comparison of something with itself. (For IEEE
9705 floating-point, we can only do some of these simplifications.) */
9707 {
9709 {
9724 /* For NE, we can only do this simplification if integer
9725 or we don't honor IEEE floating point NaNs. */
9729 /* ... fall through ... */
9735 }
9736 }
9738 /* If we are comparing an expression that just has comparisons
9739 of two integer values, arithmetic expressions of those comparisons,
9740 and constants, we can simplify it. There are only three cases
9741 to check: the two values can either be equal, the first can be
9742 greater, or the second can be greater. Fold the expression for
9743 those three values. Since each value must be 0 or 1, we have
9744 eight possibilities, each of which corresponds to the constant 0
9745 or 1 or one of the six possible comparisons.
9747 This handles common cases like (a > b) == 0 but also handles
9748 expressions like ((x > y) - (y > x)) > 0, which supposedly
9749 occur in macroized code. */
9752 {
9757 /* Don't handle degenerate cases here; they should already
9758 have been handled anyway. */
9767 {
9771 /* We can't just pass T to eval_subst in case cval1 or cval2
9772 was the same as ARG1. */
9774 tree high_result
9778 arg1);
9779 tree equal_result
9783 arg1);
9784 tree low_result
9788 arg1);
9790 /* All three of these results should be 0 or 1. Confirm they are.
9791 Then use those values to select the proper code to use. */
9796 {
9797 /* Make a 3-bit mask with the high-order bit being the
9798 value for `>', the next for '=', and the low for '<'. */
9802 {
9804 /* Always false. */
9825 /* Always true. */
9827 }
9830 {
9834 }
9836 }
9837 }
9838 }
9840 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9841 into a single range test. */
9849 {
9853 }
9855 /* Fold ~X op ~Y as Y op X. */
9858 {
9864 }
9866 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9869 {
9875 }
9878 }
9881 /* Subroutine of fold_binary. Optimize complex multiplications of the
9882 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9883 argument EXPR represents the expression "z" of type TYPE. */
9885 static tree
9887 {
9892 {
9895 }
9897 {
9900 }
9901 else
9902 {
9906 }
9915 }
9918 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9919 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9920 guarantees that P and N have the same least significant log2(M) bits.
9921 N is not otherwise constrained. In particular, N is not normalized to
9922 0 <= N < M as is common. In general, the precise value of P is unknown.
9923 M is chosen as large as possible such that constant N can be determined.
9925 Returns M and sets *RESIDUE to N.
9927 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9928 account. This is not always possible due to PR 35705.
9929 */
9931 static unsigned HOST_WIDE_INT
9934 {
9941 {
9944 {
9946 tree offset;
9954 {
9957 else
9958 /* We don't handle more complicated offset expressions. */
9960 }
9961 }
9966 }
9968 {
9976 allow_func_align);
9982 {
9985 }
9987 {
9990 {
9993 /* Compute the greatest power-of-2 divisor of op1. */
9997 /* If align is non-zero and less than *modulus, replace
9998 *modulus with align., If align is 0, then either op1 is 0
9999 or the greatest power-of-2 divisor of op1 doesn't fit in an
10000 unsigned HOST_WIDE_INT. In either case, no additional
10001 constraint is imposed. */
10006 }
10007 }
10008 }
10010 /* If we get here, we were unable to determine anything useful about the
10011 expression. */
10013 }
10016 /* Fold a binary expression of code CODE and type TYPE with operands
10017 OP0 and OP1. LOC is the location of the resulting expression.
10018 Return the folded expression if folding is successful. Otherwise,
10019 return NULL_TREE. */
10021 tree
10024 {
10038 /* Strip any conversions that don't change the mode. This is
10039 safe for every expression, except for a comparison expression
10040 because its signedness is derived from its operands. So, in
10041 the latter case, only strip conversions that don't change the
10042 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10043 preserved.
10045 Note that this is done as an internal manipulation within the
10046 constant folder, in order to find the simplest representation
10047 of the arguments so that their form can be studied. In any
10048 cases, the appropriate type conversions should be put back in
10049 the tree that will get out of the constant folder. */
10052 {
10055 }
10056 else
10057 {
10060 }
10062 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10063 constant but we can't do arithmetic on them. */
10070 {
10072 {
10073 /* Make sure type and arg0 have the same saturating flag. */
10077 }
10080 else
10084 {
10088 }
10089 }
10091 /* If this is a commutative operation, and ARG0 is a constant, move it
10092 to ARG1 to reduce the number of tests below. */
10097 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10099 First check for cases where an arithmetic operation is applied to a
10100 compound, conditional, or comparison operation. Push the arithmetic
10101 operation inside the compound or conditional to see if any folding
10102 can then be done. Convert comparison to conditional for this purpose.
10103 The also optimizes non-constant cases that used to be done in
10104 expand_expr.
10106 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10107 one of the operands is a comparison and the other is a comparison, a
10108 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10109 code below would make the expression more complex. Change it to a
10110 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10111 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10123 {
10127 boolean_type_node,
10135 }
10139 {
10141 {
10147 }
10150 {
10156 }
10159 {
10165 }
10168 {
10174 }
10175 }
10178 {
10180 /* 0 +p index -> (type)index */
10184 /* PTR +p 0 -> PTR */
10188 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10194 arg1),
10196 arg0)));
10198 /* index +p PTR -> PTR +p index */
10205 /* (PTR +p B) +p A -> PTR +p (B + A) */
10207 {
10208 tree inner;
10217 }
10219 /* PTR_CST +p CST -> CST1 */
10224 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10225 of the array. Loop optimizer sometimes produce this type of
10226 expressions. */
10228 {
10233 }
10238 /* A + (-B) -> A - B */
10244 /* (-A) + B -> B - A */
10253 {
10254 /* Convert ~A + 1 to -A. */
10261 /* ~X + X is -1. */
10264 {
10269 {
10272 }
10273 }
10275 /* X + ~X is -1. */
10278 {
10283 {
10286 }
10287 }
10289 /* X + (X / CST) * -CST is X % CST. */
10294 {
10303 cst0));
10304 }
10305 }
10307 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
10308 same or one. Make sure type is not saturating.
10309 fold_plusminus_mult_expr will re-associate. */
10314 {
10318 }
10321 {
10325 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10326 with a constant, and the two constants have no bits in common,
10327 we should treat this as a BIT_IOR_EXPR since this may produce more
10328 simplifications. */
10336 {
10339 }
10341 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10342 (plus (plus (mult) (mult)) (foo)) so that we can
10343 take advantage of the factoring cases below. */
10350 {
10356 else
10369 parg0),
10371 marg)),
10375 return
10381 parg1)));
10382 }
10383 }
10384 else
10385 {
10386 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10390 /* Likewise if the operands are reversed. */
10394 /* Convert X + -C into X - C. */
10397 {
10403 }
10405 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10406 to __complex__ ( x, y ). This is not the same for SNaNs or
10407 if signed zeros are involved. */
10411 {
10418 {
10422 {
10428 }
10430 {
10436 }
10437 }
10438 }
10446 /* Convert x+x into x*2.0. */
10452 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10453 We associate floats only if the user has specified
10454 -fassociative-math. */
10458 {
10463 {
10464 tree tree0;
10467 }
10468 }
10469 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10470 We associate floats only if the user has specified
10471 -fassociative-math. */
10475 {
10480 {
10481 tree tree0;
10484 }
10485 }
10486 }
10488 bit_rotate:
10489 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10490 is a rotate of A by C1 bits. */
10491 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10492 is a rotate of A by B bits. */
10493 {
10495 tree rtype;
10504 /* Only create rotates in complete modes. Other cases are not
10505 expanded properly. */
10507 {
10523 {
10527 code0 == LSHIFT_EXPR
10531 }
10533 {
10541 TYPE_PRECISION
10545 return
10548 ? LROTATE_EXPR
10552 }
10554 {
10562 TYPE_PRECISION
10566 return fold_convert_loc
10569 ? LROTATE_EXPR
10573 }
10574 }
10575 }
10577 associate:
10578 /* In most languages, can't associate operations on floats through
10579 parentheses. Rather than remember where the parentheses were, we
10580 don't associate floats at all, unless the user has specified
10581 -fassociative-math.
10582 And, we need to make sure type is not saturating. */
10586 {
10591 /* Split both trees into variables, constants, and literals. Then
10592 associate each group together, the constants with literals,
10593 then the result with variables. This increases the chances of
10594 literals being recombined later and of generating relocatable
10595 expressions for the sum of a constant and literal. */
10600 /* With undefined overflow we can only associate constants
10601 with one variable. */
10605 {
10613 /* The only case we can still associate with two variables
10614 is if they are the same, modulo negation. */
10617 }
10619 /* Only do something if we found more than two objects. Otherwise,
10620 nothing has changed and we risk infinite recursion. */
10626 {
10627 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10636 /* Preserve the MINUS_EXPR if the negative part of the literal is
10637 greater than the positive part. Otherwise, the multiplicative
10638 folding code (i.e extract_muldiv) may be fooled in case
10639 unsigned constants are subtracted, like in the following
10640 example: ((X*2 + 4) - 8U)/2. */
10642 {
10646 {
10650 }
10651 else
10652 {
10656 }
10657 }
10659 {
10661 return
10665 else
10666 {
10669 return
10673 }
10674 }
10677 return
10680 }
10681 }
10686 /* Pointer simplifications for subtraction, simple reassociations. */
10688 {
10689 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10692 {
10702 }
10703 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10705 {
10712 }
10713 }
10714 /* A - (-B) -> A + B */
10719 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10730 /* Convert -A - 1 to ~A. */
10739 /* Convert -1 - A to ~A. */
10745 /* X - (X / CST) * CST is X % CST. */
10753 return
10759 {
10765 /* Fold A - (A & B) into ~B & A. */
10768 {
10770 {
10777 }
10779 {
10786 }
10787 }
10789 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10790 any power of 2 minus 1. */
10795 {
10801 {
10805 }
10806 }
10807 }
10809 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10813 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10814 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10815 (-ARG1 + ARG0) reduces to -ARG1. */
10819 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10820 __complex__ ( x, -y ). This is not the same for SNaNs or if
10821 signed zeros are involved. */
10825 {
10832 {
10836 {
10838 arg1r ? arg1r
10843 }
10845 {
10849 arg1i ? arg1i
10852 }
10853 }
10854 }
10856 /* Fold &x - &x. This can happen from &x.foo - &x.
10857 This is unsafe for certain floats even in non-IEEE formats.
10858 In IEEE, it is unsafe because it does wrong for NaNs.
10859 Also note that operand_equal_p is always false if an operand
10860 is volatile. */
10866 /* A - B -> A + (-B) if B is easily negatable. */
10869 /* Avoid this transformation if B is a positive REAL_CST. */
10878 /* Try folding difference of addresses. */
10879 {
10880 HOST_WIDE_INT diff;
10886 }
10888 /* Fold &a[i] - &a[j] to i-j. */
10893 {
10898 {
10906 }
10907 }
10910 && flag_unsafe_math_optimizations
10916 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10917 same or one. Make sure type is not saturating.
10918 fold_plusminus_mult_expr will re-associate. */
10923 {
10927 }
10932 /* (-A) * (-B) -> A * B */
10947 {
10952 /* Transform x * -1 into -x. Make sure to do the negation
10953 on the original operand with conversions not stripped
10954 because we can only strip non-sign-changing conversions. */
10957 /* Transform x * -C into -x * C if x is easily negatable. */
10966 tem);
10968 /* (a * (1 << b)) is (a << b) */
10978 /* (A + A) * C -> A * 2 * C */
10994 {
10997 "occur when simplifying "
10999 WARN_STRICT_OVERFLOW_MISC);
11001 }
11003 /* Optimize z * conj(z) for integer complex numbers. */
11010 }
11011 else
11012 {
11013 /* Maybe fold x * 0 to 0. The expressions aren't the same
11014 when x is NaN, since x * 0 is also NaN. Nor are they the
11015 same in modes with signed zeros, since multiplying a
11016 negative value by 0 gives -0, not +0. */
11021 /* In IEEE floating point, x*1 is not equivalent to x for snans.
11022 Likewise for complex arithmetic with signed zeros. */
11029 /* Transform x * -1.0 into -x. */
11036 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
11037 the result for floating point types due to rounding so it is applied
11038 only if -fassociative-math was specify. */
11043 {
11049 }
11051 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
11053 {
11056 {
11059 }
11060 }
11062 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11063 This is not the same for NaNs or if signed zeros are
11064 involved. */
11070 {
11073 return
11079 return
11084 }
11086 /* Optimize z * conj(z) for floating point complex numbers.
11087 Guarded by flag_unsafe_math_optimizations as non-finite
11088 imaginary components don't produce scalar results. */
11099 {
11103 /* Optimizations of root(...)*root(...). */
11105 {
11110 /* Optimize sqrt(x)*sqrt(x) as x. */
11116 /* Optimize root(x)*root(y) as root(x*y). */
11120 }
11122 /* Optimize expN(x)*expN(y) as expN(x+y). */
11124 {
11130 }
11132 /* Optimizations of pow(...)*pow(...). */
11136 {
11142 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11144 {
11149 }
11151 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11153 {
11158 }
11159 }
11161 /* Optimize tan(x)*cos(x) as sin(x). */
11170 {
11176 }
11178 /* Optimize x*pow(x,c) as pow(x,c+1). */
11182 {
11188 {
11190 REAL_VALUE_TYPE c;
11191 tree arg;
11197 }
11198 }
11200 /* Optimize pow(x,c)*x as pow(x,c+1). */
11204 {
11210 {
11212 REAL_VALUE_TYPE c;
11213 tree arg;
11219 }
11220 }
11222 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
11225 {
11229 {
11232 }
11233 }
11234 }
11235 }
11239 bit_ior:
11247 /* ~X | X is -1. */
11250 {
11254 }
11256 /* X | ~X is -1. */
11259 {
11263 }
11265 /* Canonicalize (X & C1) | C2. */
11269 {
11277 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11283 {
11287 }
11288 else
11289 {
11293 }
11295 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11300 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11301 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11302 mode which allows further optimizations. */
11312 {
11313 unsigned HOST_WIDE_INT mask
11317 {
11321 }
11322 }
11329 arg1);
11330 }
11332 /* (X & Y) | Y is (X, Y). */
11336 /* (X & Y) | X is (Y, X). */
11341 /* X | (X & Y) is (Y, X). */
11346 /* X | (Y & X) is (Y, X). */
11356 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11358 This results in more efficient code for machines without a NAND
11359 instruction. Combine will canonicalize to the first form
11360 which will allow use of NAND instructions provided by the
11361 backend if they exist. */
11364 {
11365 return
11372 }
11374 /* See if this can be simplified into a rotate first. If that
11375 is unsuccessful continue in the association code. */
11386 /* ~X ^ X is -1. */
11389 {
11393 }
11395 /* X ^ ~X is -1. */
11398 {
11402 }
11404 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11405 with a constant, and the two constants have no bits in common,
11406 we should treat this as a BIT_IOR_EXPR since this may produce more
11407 simplifications. */
11415 {
11418 }
11420 /* (X | Y) ^ X -> Y & ~ X*/
11423 {
11426 arg1);
11431 }
11433 /* (Y | X) ^ X -> Y & ~ X*/
11436 {
11439 arg1);
11444 }
11446 /* X ^ (X | Y) -> Y & ~ X*/
11449 {
11452 arg0);
11457 }
11459 /* X ^ (Y | X) -> Y & ~ X*/
11462 {
11465 arg0);
11470 }
11472 /* Convert ~X ^ ~Y to X ^ Y. */
11481 /* Convert ~X ^ C to X ^ ~C. */
11489 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11496 /* Fold (X & Y) ^ Y as ~X & Y. */
11499 {
11504 }
11505 /* Fold (X & Y) ^ X as ~Y & X. */
11509 {
11514 }
11515 /* Fold X ^ (X & Y) as X & ~Y. */
11518 {
11523 }
11524 /* Fold X ^ (Y & X) as ~Y & X. */
11528 {
11533 }
11535 /* See if this can be simplified into a rotate first. If that
11536 is unsuccessful continue in the association code. */
11547 /* ~X & X is always zero. */
11552 /* X & ~X is always zero. */
11557 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11561 {
11567 return
11571 }
11573 /* (X | Y) & Y is (X, Y). */
11577 /* (X | Y) & X is (Y, X). */
11582 /* X & (X | Y) is (Y, X). */
11587 /* X & (Y | X) is (Y, X). */
11593 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11597 {
11603 }
11604 /* Fold ~X & 1 as (X & 1) == 0. */
11607 {
11613 }
11615 /* Fold (X ^ Y) & Y as ~X & Y. */
11618 {
11623 }
11624 /* Fold (X ^ Y) & X as ~Y & X. */
11628 {
11633 }
11634 /* Fold X & (X ^ Y) as X & ~Y. */
11637 {
11642 }
11643 /* Fold X & (Y ^ X) as ~Y & X. */
11647 {
11652 }
11657 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11660 {
11661 unsigned int prec
11667 return
11669 }
11671 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11673 This results in more efficient code for machines without a NOR
11674 instruction. Combine will canonicalize to the first form
11675 which will allow use of NOR instructions provided by the
11676 backend if they exist. */
11679 {
11686 }
11688 /* If arg0 is derived from the address of an object or function, we may
11689 be able to fold this expression using the object or function's
11690 alignment. */
11692 {
11699 /* This works because modulus is a power of 2. If this weren't the
11700 case, we'd have to replace it by its greatest power-of-2
11701 divisor: modulus & -modulus. */
11704 }
11706 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11707 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11708 if the new mask might be further optimized. */
11717 {
11719 unsigned HOST_WIDE_INT mask
11729 {
11732 /* See if more bits can be proven as zero because of
11733 zero extension. */
11736 {
11741 {
11743 /* See if we can shorten the right shift. */
11746 }
11747 }
11751 /* For arithmetic shift if sign bit could be set, zerobits
11752 can contain actually sign bits, so no transformation is
11753 possible, unless MASK masks them all away. In that
11754 case the shift needs to be converted into logical shift. */
11757 {
11760 else
11762 }
11763 }
11765 /* ((X << 16) & 0xff00) is (X, 0). */
11772 {
11775 /* Only do the transformation if NEWMASK is some integer
11776 mode's mask. */
11783 {
11784 tree newmaskt;
11787 {
11793 }
11794 else
11799 }
11800 }
11801 }
11806 /* Don't touch a floating-point divide by zero unless the mode
11807 of the constant can represent infinity. */
11813 /* Optimize A / A to 1.0 if we don't care about
11814 NaNs or Infinities. Skip the transformation
11815 for non-real operands. */
11820 {
11824 }
11826 /* The complex version of the above A / A optimization. */
11829 {
11833 {
11835 /* omit_two_operands will call fold_convert for us. */
11837 }
11838 }
11840 /* (-A) / (-B) -> A / B */
11850 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11855 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11861 /* If ARG1 is a constant, we can convert this to a multiply by the
11862 reciprocal. This does not have the same rounding properties,
11863 so only do this if -freciprocal-math. We can actually
11864 always safely do it if ARG1 is a power of two, but it's hard to
11865 tell if it is or not in a portable manner. */
11867 {
11872 /* Find the reciprocal if optimizing and the result is exact. */
11874 {
11875 REAL_VALUE_TYPE r;
11878 {
11882 }
11883 }
11884 }
11885 /* Convert A/B/C to A/(B*C). */
11892 /* Convert A/(B/C) to (A/B)*C. */
11900 /* Convert C1/(X*C2) into (C1/C2)/X. */
11905 {
11911 }
11914 {
11918 /* Optimize sin(x)/cos(x) as tan(x). */
11924 {
11929 }
11931 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11937 {
11941 {
11946 }
11947 }
11949 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11950 NaNs or Infinities. */
11954 {
11961 {
11966 }
11967 }
11969 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11970 NaNs or Infinities. */
11974 {
11981 {
11985 {
11989 tmp);
11990 }
11991 }
11992 }
11994 /* Optimize pow(x,c)/x as pow(x,c-1). */
11998 {
12004 {
12006 REAL_VALUE_TYPE c;
12007 tree arg;
12013 }
12014 }
12016 /* Optimize a/root(b/c) into a*root(c/b). */
12018 {
12022 {
12031 }
12032 }
12034 /* Optimize x/expN(y) into x*expN(-y). */
12036 {
12043 }
12045 /* Optimize x/pow(y,z) into x*pow(y,-z). */
12049 {
12057 }
12058 }
12063 /* Simplify A / (B << N) where A and B are positive and B is
12064 a power of 2, to A >> (N + log2(B)). */
12069 {
12072 {
12079 WARN_STRICT_OVERFLOW_MISC);
12085 }
12086 }
12088 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
12089 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12095 /* Fall thru */
12104 /* X / -1 is -X. */
12111 /* Convert -A / -B to A / B when the type is signed and overflow is
12112 undefined. */
12116 {
12119 "when distributing negation across "
12121 WARN_STRICT_OVERFLOW_MISC);
12127 }
12131 {
12134 "when distributing negation across "
12136 WARN_STRICT_OVERFLOW_MISC);
12142 }
12144 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12145 operation, EXACT_DIV_EXPR.
12147 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12148 At one time others generated faster code, it's not clear if they do
12149 after the last round to changes to the DIV code in expmed.c. */
12158 {
12162 WARN_STRICT_OVERFLOW_MISC);
12164 }
12172 /* X % 1 is always zero, but be sure to preserve any side
12173 effects in X. */
12177 /* X % 0, return X % 0 unchanged so that we can get the
12178 proper warnings and errors. */
12182 /* 0 % X is always zero, but be sure to preserve any side
12183 effects in X. Place this after checking for X == 0. */
12187 /* X % -1 is zero. */
12194 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12195 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12200 {
12202 /* Also optimize A % (C << N) where C is a power of 2,
12203 to A & ((C << N) - 1). */
12208 {
12213 "occur when simplifying "
12215 WARN_STRICT_OVERFLOW_MISC);
12219 }
12220 }
12222 /* X % -C is the same as X % C. */
12229 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12236 /* X % -Y is the same as X % Y. */
12248 {
12252 WARN_STRICT_OVERFLOW_MISC);
12254 }
12265 /* Optimize -1 >> x for arithmetic right shifts. */
12269 /* ... fall through ... */
12272 shift:
12278 /* Since negative shift count is not well-defined,
12279 don't try to compute it in the compiler. */
12283 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12288 {
12292 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12293 being well defined. */
12295 {
12301 else
12303 }
12307 }
12309 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12310 into x & ((unsigned)-1 >> c) for unsigned types. */
12318 {
12321 tree lshift;
12322 tree arg00;
12325 {
12332 }
12333 }
12335 /* Rewrite an LROTATE_EXPR by a constant into an
12336 RROTATE_EXPR by a new constant. */
12338 {
12343 }
12345 /* If we have a rotate of a bit operation with the rotate count and
12346 the second operand of the bit operation both constant,
12347 permute the two operations. */
12359 /* Two consecutive rotates adding up to the precision of the
12360 type can be ignored. */
12371 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12372 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12373 if the latter can be further optimized. */
12378 {
12382 arg1);
12386 arg1);
12390 }
12418 /* Note that the operands of this must be ints
12419 and their values must be 0 or 1.
12420 ("true" is a fixed value perhaps depending on the language.) */
12421 /* If first arg is constant zero, return it. */
12425 /* If either arg is constant true, drop it. */
12429 /* Preserve sequence points. */
12432 /* If second arg is constant zero, result is zero, but first arg
12433 must be evaluated. */
12436 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12437 case will be handled here. */
12441 /* !X && X is always false. */
12445 /* X && !X is always false. */
12450 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12451 means A >= Y && A != MAX, but in this case we know that
12452 A < X <= MAX. */
12456 {
12464 }
12466 truth_andor:
12467 /* We only do these simplifications if we are optimizing. */
12471 /* Check for things like (A || B) && (A || C). We can convert this
12472 to A || (B && C). Note that either operator can be any of the four
12473 truth and/or operations and the transformation will still be
12474 valid. Also note that we only care about order for the
12475 ANDIF and ORIF operators. If B contains side effects, this
12476 might change the truth-value of A. */
12483 {
12503 /* This case if tricky because we must either have commutative
12504 operators or else A10 must not have side-effects. */
12510 a01);
12511 }
12513 /* See if we can build a range comparison. */
12517 /* Check for the possibility of merging component references. If our
12518 lhs is another similar operation, try to merge its rhs with our
12519 rhs. Then try to merge our lhs and rhs. */
12531 /* Note that the operands of this must be ints
12532 and their values must be 0 or true.
12533 ("true" is a fixed value perhaps depending on the language.) */
12534 /* If first arg is constant true, return it. */
12538 /* If either arg is constant zero, drop it. */
12542 /* Preserve sequence points. */
12545 /* If second arg is constant true, result is true, but we must
12546 evaluate first arg. */
12549 /* Likewise for first arg, but note this only occurs here for
12550 TRUTH_OR_EXPR. */
12554 /* !X || X is always true. */
12558 /* X || !X is always true. */
12566 /* If the second arg is constant zero, drop it. */
12569 /* If the second arg is constant true, this is a logical inversion. */
12571 {
12572 /* Only call invert_truthvalue if operand is a truth value. */
12575 else
12578 }
12579 /* Identical arguments cancel to zero. */
12583 /* !X ^ X is always true. */
12588 /* X ^ !X is always true. */
12601 /* bool_var != 0 becomes bool_var. */
12606 /* bool_var == 1 becomes bool_var. */
12611 /* bool_var != 1 becomes !bool_var. */
12617 /* bool_var == 0 becomes !bool_var. */
12623 /* !exp != 0 becomes !exp */
12628 /* If this is an equality comparison of the address of two non-weak,
12629 unaliased symbols neither of which are extern (since we do not
12630 have access to attributes for externs), then we know the result. */
12643 {
12644 /* We know that we're looking at the address of two
12645 non-weak, unaliased, static _DECL nodes.
12647 It is both wasteful and incorrect to call operand_equal_p
12648 to compare the two ADDR_EXPR nodes. It is wasteful in that
12649 all we need to do is test pointer equality for the arguments
12650 to the two ADDR_EXPR nodes. It is incorrect to use
12651 operand_equal_p as that function is NOT equivalent to a
12652 C equality test. It can in fact return false for two
12653 objects which would test as equal using the C equality
12654 operator. */
12658 type);
12659 }
12661 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12662 a MINUS_EXPR of a constant, we can convert it into a comparison with
12663 a revised constant as long as no overflow occurs. */
12671 arg1),
12676 /* Similarly for a NEGATE_EXPR. */
12684 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12692 arg1),
12695 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12702 {
12706 val,
12710 }
12712 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12717 {
12719 code == NE_EXPR
12722 }
12724 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12725 for !=. Don't do this for ordered comparisons due to overflow. */
12731 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12736 /* If this is an EQ or NE comparison with zero and ARG0 is
12737 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12738 two operations, but the latter can be done in one less insn
12739 on machines that have only two-operand insns or on which a
12740 constant cannot be the first operand. */
12743 {
12748 {
12755 arg1);
12756 }
12759 {
12766 arg1);
12767 }
12768 }
12770 /* If this is an NE or EQ comparison of zero against the result of a
12771 signed MOD operation whose second operand is a power of 2, make
12772 the MOD operation unsigned since it is simpler and equivalent. */
12780 {
12790 }
12792 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12793 C1 is a valid shift constant, and C2 is a power of two, i.e.
12794 a single bit. */
12798 == INTEGER_CST
12801 {
12806 /* Check for a valid shift count. */
12809 {
12813 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12814 can be rewritten as (X & (C2 << C1)) != 0. */
12816 {
12820 }
12821 /* Otherwise, for signed (arithmetic) shifts,
12822 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12823 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12827 /* Otherwise, of unsigned (logical) shifts,
12828 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12829 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12830 else
12834 arg000);
12835 }
12836 }
12838 /* If this is an NE comparison of zero with an AND of one, remove the
12839 comparison since the AND will give the correct value. */
12846 /* If we have (A & C) == C where C is a power of 2, convert this into
12847 (A & C) != 0. Similarly for NE_EXPR. */
12853 integer_zero_node));
12855 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12856 bit, then fold the expression into A < 0 or A >= 0. */
12861 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12862 Similarly for NE_EXPR. */
12866 {
12875 }
12877 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12878 Similarly for NE_EXPR. */
12882 {
12889 }
12891 /* If this is a comparison of a field, we may be able to simplify it. */
12894 /* Handle the constant case even without -O
12895 to make sure the warnings are given. */
12897 {
12901 }
12903 /* Optimize comparisons of strlen vs zero to a compare of the
12904 first character of the string vs zero. To wit,
12905 strlen(ptr) == 0 => *ptr == 0
12906 strlen(ptr) != 0 => *ptr != 0
12907 Other cases should reduce to one of these two (or a constant)
12908 due to the return value of strlen being unsigned. */
12911 {
12919 {
12924 }
12925 }
12927 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12928 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12932 {
12939 {
12941 {
12944 }
12947 }
12948 }
12950 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12956 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12961 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12968 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12976 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12977 (X & C) == 0 when C is a single bit. */
12982 {
12988 }
12990 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12991 constant C is a power of two, i.e. a single bit. */
12998 {
13002 }
13004 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
13005 when is C is a power of two, i.e. a single bit. */
13012 {
13018 }
13022 {
13025 }
13027 /* Fold -X op -Y as X op Y, where op is eq/ne. */
13034 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
13037 {
13050 arg01),
13059 arg01),
13068 arg00),
13077 arg00),
13079 }
13083 {
13090 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
13091 operand_equal_p guarantees no side-effects so we don't need
13092 to use omit_one_operand on Z. */
13102 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13110 arg10);
13111 }
13113 /* Attempt to simplify equality/inequality comparisons of complex
13114 values. Only lower the comparison if the result is known or
13115 can be simplified to a single scalar comparison. */
13120 {
13125 {
13128 }
13129 else
13130 {
13133 }
13136 {
13139 }
13140 else
13141 {
13144 }
13148 {
13150 {
13155 }
13156 else
13157 {
13162 }
13163 }
13167 {
13169 {
13174 }
13175 else
13176 {
13181 }
13182 }
13183 }
13195 /* Transform comparisons of the form X +- C CMP X. */
13202 {
13209 else
13212 /* (X - c) > X becomes false. */
13216 {
13220 "occur when assuming that (X - c) > X "
13222 WARN_STRICT_OVERFLOW_ALL);
13224 }
13226 /* Likewise (X + c) < X becomes false. */
13230 {
13234 "occur when assuming that "
13236 WARN_STRICT_OVERFLOW_ALL);
13238 }
13240 /* Convert (X - c) <= X to true. */
13245 {
13249 "occur when assuming that "
13251 WARN_STRICT_OVERFLOW_ALL);
13253 }
13255 /* Convert (X + c) >= X to true. */
13260 {
13264 "occur when assuming that "
13266 WARN_STRICT_OVERFLOW_ALL);
13268 }
13271 {
13272 /* Convert X + c > X and X - c < X to true for integers. */
13276 {
13279 "not occur when assuming that "
13281 WARN_STRICT_OVERFLOW_ALL);
13283 }
13288 {
13291 "not occur when assuming that "
13293 WARN_STRICT_OVERFLOW_ALL);
13295 }
13297 /* Convert X + c <= X and X - c >= X to false for integers. */
13301 {
13304 "not occur when assuming that "
13306 WARN_STRICT_OVERFLOW_ALL);
13308 }
13313 {
13316 "not occur when assuming that "
13318 WARN_STRICT_OVERFLOW_ALL);
13320 }
13321 }
13322 }
13324 /* Comparisons with the highest or lowest possible integer of
13325 the specified precision will have known values. */
13326 {
13333 {
13334 HOST_WIDE_INT signed_max_hi;
13339 {
13346 {
13350 }
13351 else
13352 {
13356 }
13357 }
13358 else
13359 {
13368 {
13371 }
13372 else
13373 {
13376 }
13377 }
13382 {
13395 /* The GE_EXPR and LT_EXPR cases above are not normally
13396 reached because of previous transformations. */
13400 }
13402 == max_hi
13405 {
13412 arg1);
13418 arg0),
13419 arg1);
13422 }
13424 == min_hi
13427 {
13442 }
13444 == min_hi
13447 {
13453 arg1);
13458 arg0),
13459 arg1);
13462 }
13467 /* We will flip the signedness of the comparison operator
13468 associated with the mode of arg1, so the sign bit is
13469 specified by this mode. Check that arg1 is the signed
13470 max associated with this sign bit. */
13472 /* signed_type does not work on pointer types. */
13474 {
13475 /* The following case also applies to X < signed_max+1
13476 and X >= signed_max+1 because previous transformations. */
13478 {
13479 tree st;
13485 }
13486 }
13487 }
13488 }
13490 /* If we are comparing an ABS_EXPR with a constant, we can
13491 convert all the cases into explicit comparisons, but they may
13492 well not be faster than doing the ABS and one comparison.
13493 But ABS (X) <= C is a range comparison, which becomes a subtraction
13494 and a comparison, and is probably faster. */
13508 /* Convert ABS_EXPR<x> >= 0 to true. */
13515 {
13518 "when simplifying comparison of "
13520 WARN_STRICT_OVERFLOW_CONDITIONAL);
13522 }
13524 /* Convert ABS_EXPR<x> < 0 to false. */
13529 {
13532 "when simplifying comparison of "
13534 WARN_STRICT_OVERFLOW_CONDITIONAL);
13536 }
13538 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13539 and similarly for >= into !=. */
13544 {
13550 }
13557 {
13566 }
13579 {
13583 }
13585 /* If the first operand is NaN, the result is constant. */
13589 {
13591 ? integer_zero_node
13594 }
13596 /* If the second operand is NaN, the result is constant. */
13600 {
13602 ? integer_zero_node
13605 }
13607 /* Simplify unordered comparison of something with itself. */
13613 && !flag_trapping_math
13617 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13618 {
13630 }
13635 /* When pedantic, a compound expression can be neither an lvalue
13636 nor an integer constant expression. */
13639 /* Don't let (0, 0) be null pointer constant. */
13653 /* An ASSERT_EXPR should never be passed to fold_binary. */
13659 fold_binary_exit:
13662 }
13664 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13665 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13666 of GOTO_EXPR. */
13668 static tree
13670 {
13672 {
13679 /* ... fall through ... */
13683 }
13684 }
13686 /* Return whether the sub-tree ST contains a label which is accessible from
13687 outside the sub-tree. */
13689 static bool
13691 {
13692 return
13694 }
13696 /* Fold a ternary expression of code CODE and type TYPE with operands
13697 OP0, OP1, and OP2. Return the folded expression if folding is
13698 successful. Otherwise, return NULL_TREE. */
13700 tree
13703 {
13704 tree tem;
13711 /* Strip any conversions that don't change the mode. This is safe
13712 for every expression, except for a comparison expression because
13713 its signedness is derived from its operands. So, in the latter
13714 case, only strip conversions that don't change the signedness.
13716 Note that this is done as an internal manipulation within the
13717 constant folder, in order to find the simplest representation of
13718 the arguments so that their form can be studied. In any cases,
13719 the appropriate type conversions should be put back in the tree
13720 that will get out of the constant folder. */
13722 {
13725 }
13728 {
13731 }
13734 {
13738 {
13744 }
13748 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13749 so all simple results must be passed through pedantic_non_lvalue. */
13751 {
13754 /* Only optimize constant conditions when the selected branch
13755 has the same type as the COND_EXPR. This avoids optimizing
13756 away "c ? x : throw", where the throw has a void type.
13757 Avoid throwing away that operand which contains label. */
13764 }
13768 /* If we have A op B ? A : C, we may be able to convert this to a
13769 simpler expression, depending on the operation and the values
13770 of B and C. Signed zeros prevent all of these transformations,
13771 for reasons given above each one.
13773 Also try swapping the arguments and inverting the conditional. */
13778 {
13782 }
13786 op2,
13789 {
13792 {
13796 }
13797 }
13799 /* If the second operand is simpler than the third, swap them
13800 since that produces better jump optimization results. */
13803 {
13804 /* See if this can be inverted. If it can't, possibly because
13805 it was a floating-point inequality comparison, don't do
13806 anything. */
13810 }
13812 /* Convert A ? 1 : 0 to simply A. */
13815 /* If we try to convert OP0 to our type, the
13816 call to fold will try to move the conversion inside
13817 a COND, which will recurse. In that case, the COND_EXPR
13818 is probably the best choice, so leave it alone. */
13822 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13823 over COND_EXPR in cases such as floating point comparisons. */
13830 arg0)));
13832 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13837 {
13838 /* sign_bit_p only checks ARG1 bits within A's precision.
13839 If <sign bit of A> has wider type than A, bits outside
13840 of A's precision in <sign bit of A> need to be checked.
13841 If they are all 0, this optimization needs to be done
13842 in unsigned A's type, if they are all 1 in signed A's type,
13843 otherwise this can't be done. */
13848 {
13850 HOST_WIDE_INT mask_hi;
13852 tree tem_type;
13860 {
13864 }
13865 else
13866 {
13870 }
13872 {
13876 }
13877 else
13883 {
13886 }
13889 {
13892 }
13893 else
13895 }
13898 return
13904 arg1)));
13905 }
13907 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13908 already handled above. */
13913 {
13922 }
13924 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13925 is probably obsolete because the first operand should be a
13926 truth value (that's why we have the two cases above), but let's
13927 leave it in until we can confirm this for all front-ends. */
13939 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13945 arg1);
13947 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13951 {
13952 /* Only perform transformation if ARG0 is easily inverted. */
13957 arg1);
13958 }
13960 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13964 {
13965 /* Only perform transformation if ARG0 is easily inverted. */
13970 op2);
13971 }
13973 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13979 op2);
13984 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13985 of fold_ternary on them. */
13992 {
14001 {
14006 else
14007 {
14009 tree value;
14013 }
14018 else
14020 }
14021 }
14023 /* A bit-field-ref that referenced the full argument can be stripped. */
14034 }
14036 /* Perform constant folding and related simplification of EXPR.
14037 The related simplifications include x*1 => x, x*0 => 0, etc.,
14038 and application of the associative law.
14039 NOP_EXPR conversions may be removed freely (as long as we
14040 are careful not to change the type of the overall expression).
14041 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14042 but we can constant-fold them if they have constant operands. */
14044 #ifdef ENABLE_FOLD_CHECKING
14045 # define fold(x) fold_1 (x)
14047 static
14048 #endif
14049 tree
14051 {
14055 tree tem;
14058 /* Return right away if a constant. */
14062 /* CALL_EXPR-like objects with variable numbers of operands are
14063 treated specially. */
14065 {
14067 {
14070 }
14072 }
14075 {
14080 {
14098 }
14099 }
14102 {
14104 {
14111 {
14116 /* Find a matching index by means of a binary search. */
14118 {
14134 else
14136 }
14137 }
14140 }
14148 }
14150 #ifdef ENABLE_FOLD_CHECKING
14151 #undef fold
14157 /* When --enable-checking=fold, compute a digest of expr before
14158 and after actual fold call to see if fold did not accidentally
14159 change original expr. */
14161 tree
14163 {
14164 tree ret;
14167 htab_t ht;
14186 }
14188 void
14190 {
14193 htab_t ht;
14203 }
14205 static void
14207 {
14209 }
14211 static void
14213 {
14219 recursive_label:
14233 {
14234 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14238 }
14245 {
14246 /* Allow these fields to be modified. */
14247 tree tmp;
14255 {
14258 }
14259 }
14268 {
14271 {
14285 }
14289 {
14302 }
14319 {
14325 }
14330 {
14334 }
14345 {
14348 }
14358 }
14359 }
14361 /* Helper function for outputting the checksum of a tree T. When
14362 debugging with gdb, you can "define mynext" to be "next" followed
14363 by "call debug_fold_checksum (op0)", then just trace down till the
14364 outputs differ. */
14366 void
14368 {
14383 }
14385 #endif
14387 /* Fold a unary tree expression with code CODE of type TYPE with an
14388 operand OP0. LOC is the location of the resulting expression.
14389 Return a folded expression if successful. Otherwise, return a tree
14390 expression with code CODE of type TYPE with an operand OP0. */
14392 tree
14395 {
14396 tree tem;
14397 #ifdef ENABLE_FOLD_CHECKING
14400 htab_t ht;
14407 #endif
14411 {
14414 }
14416 #ifdef ENABLE_FOLD_CHECKING
14424 #endif
14426 }
14428 /* Fold a binary tree expression with code CODE of type TYPE with
14429 operands OP0 and OP1. LOC is the location of the resulting
14430 expression. Return a folded expression if successful. Otherwise,
14431 return a tree expression with code CODE of type TYPE with operands
14432 OP0 and OP1. */
14434 tree
14437 MEM_STAT_DECL)
14438 {
14439 tree tem;
14440 #ifdef ENABLE_FOLD_CHECKING
14446 htab_t ht;
14458 #endif
14462 {
14465 }
14467 #ifdef ENABLE_FOLD_CHECKING
14483 #endif
14485 }
14487 /* Fold a ternary tree expression with code CODE of type TYPE with
14488 operands OP0, OP1, and OP2. Return a folded expression if
14489 successful. Otherwise, return a tree expression with code CODE of
14490 type TYPE with operands OP0, OP1, and OP2. */
14492 tree
14495 {
14496 tree tem;
14497 #ifdef ENABLE_FOLD_CHECKING
14505 htab_t ht;
14522 #endif
14527 {
14530 }
14532 #ifdef ENABLE_FOLD_CHECKING
14556 #endif
14558 }
14560 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14561 arguments in ARGARRAY, and a null static chain.
14562 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14563 of type TYPE from the given operands as constructed by build_call_array. */
14565 tree
14568 {
14569 tree tem;
14570 #ifdef ENABLE_FOLD_CHECKING
14576 htab_t ht;
14590 #endif
14594 #ifdef ENABLE_FOLD_CHECKING
14611 #endif
14613 }
14615 /* Perform constant folding and related simplification of initializer
14616 expression EXPR. These behave identically to "fold_buildN" but ignore
14617 potential run-time traps and exceptions that fold must preserve. */
14619 #define START_FOLD_INIT \
14620 int saved_signaling_nans = flag_signaling_nans;\
14621 int saved_trapping_math = flag_trapping_math;\
14622 int saved_rounding_math = flag_rounding_math;\
14623 int saved_trapv = flag_trapv;\
14624 int saved_folding_initializer = folding_initializer;\
14625 flag_signaling_nans = 0;\
14626 flag_trapping_math = 0;\
14627 flag_rounding_math = 0;\
14628 flag_trapv = 0;\
14629 folding_initializer = 1;
14631 #define END_FOLD_INIT \
14632 flag_signaling_nans = saved_signaling_nans;\
14633 flag_trapping_math = saved_trapping_math;\
14634 flag_rounding_math = saved_rounding_math;\
14635 flag_trapv = saved_trapv;\
14636 folding_initializer = saved_folding_initializer;
14638 tree
14641 {
14642 tree result;
14643 START_FOLD_INIT;
14647 END_FOLD_INIT;
14649 }
14651 tree
14654 {
14655 tree result;
14656 START_FOLD_INIT;
14660 END_FOLD_INIT;
14662 }
14664 tree
14667 {
14668 tree result;
14669 START_FOLD_INIT;
14673 END_FOLD_INIT;
14675 }
14677 tree
14680 {
14681 tree result;
14682 START_FOLD_INIT;
14686 END_FOLD_INIT;
14688 }
14690 #undef START_FOLD_INIT
14691 #undef END_FOLD_INIT
14693 /* Determine if first argument is a multiple of second argument. Return 0 if
14694 it is not, or we cannot easily determined it to be.
14696 An example of the sort of thing we care about (at this point; this routine
14697 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14698 fold cases do now) is discovering that
14700 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14702 is a multiple of
14704 SAVE_EXPR (J * 8)
14706 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14708 This code also handles discovering that
14710 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14712 is a multiple of 8 so we don't have to worry about dealing with a
14713 possible remainder.
14715 Note that we *look* inside a SAVE_EXPR only to determine how it was
14716 calculated; it is not safe for fold to do much of anything else with the
14717 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14718 at run time. For example, the latter example above *cannot* be implemented
14719 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14720 evaluation time of the original SAVE_EXPR is not necessarily the same at
14721 the time the new expression is evaluated. The only optimization of this
14722 sort that would be valid is changing
14724 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14726 divided by 8 to
14728 SAVE_EXPR (I) * SAVE_EXPR (J)
14730 (where the same SAVE_EXPR (J) is used in the original and the
14731 transformed version). */
14733 int
14735 {
14743 {
14745 /* Bitwise and provides a power of two multiple. If the mask is
14746 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14749 /* FALLTHRU */
14762 {
14766 /* const_binop may not detect overflow correctly,
14767 so check for it explicitly here. */
14773 size_one_node,
14777 }
14781 /* Can't handle conversions from non-integral or wider integral type. */
14787 /* .. fall through ... */
14804 }
14805 }
14807 /* Return true if CODE or TYPE is known to be non-negative. */
14809 static bool
14811 {
14814 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14815 have a signed:1 type (where the value is -1 and 0). */
14818 }
14820 /* Return true if (CODE OP0) is known to be non-negative. If the return
14821 value is based on the assumption that signed overflow is undefined,
14822 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14823 *STRICT_OVERFLOW_P. */
14825 bool
14828 {
14833 {
14835 /* We can't return 1 if flag_wrapv is set because
14836 ABS_EXPR<INT_MIN> = INT_MIN. */
14840 {
14843 }
14850 strict_overflow_p);
14853 {
14858 {
14861 strict_overflow_p);
14863 {
14867 strict_overflow_p);
14868 }
14869 }
14871 {
14874 strict_overflow_p);
14878 }
14879 }
14884 }
14886 /* We don't know sign of `t', so be conservative and return false. */
14888 }
14890 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14891 value is based on the assumption that signed overflow is undefined,
14892 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14893 *STRICT_OVERFLOW_P. */
14895 bool
14898 {
14903 {
14908 strict_overflow_p)
14910 strict_overflow_p));
14912 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14913 both unsigned and at least 2 bits shorter than the result. */
14917 {
14922 {
14926 }
14927 }
14932 {
14933 /* x * x for floating point x is always non-negative. */
14937 strict_overflow_p)
14939 strict_overflow_p));
14940 }
14942 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14943 both unsigned and their total bits is shorter than the result. */
14947 {
14966 {
14976 }
14977 }
14983 strict_overflow_p)
14985 strict_overflow_p));
14996 strict_overflow_p)
14998 strict_overflow_p));
15005 strict_overflow_p);
15008 }
15010 /* We don't know sign of `t', so be conservative and return false. */
15012 }
15014 /* Return true if T is known to be non-negative. If the return
15015 value is based on the assumption that signed overflow is undefined,
15016 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15017 *STRICT_OVERFLOW_P. */
15019 bool
15021 {
15026 {
15038 strict_overflow_p)
15040 strict_overflow_p));
15044 }
15045 /* We don't know sign of `t', so be conservative and return false. */
15047 }
15049 /* Return true if T is known to be non-negative. If the return
15050 value is based on the assumption that signed overflow is undefined,
15051 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15052 *STRICT_OVERFLOW_P. */
15054 bool
15057 {
15060 {
15078 /* Always true. */
15082 /* sqrt(-0.0) is -0.0. */
15086 strict_overflow_p);
15119 /* True if the 1st argument is nonnegative. */
15121 strict_overflow_p);
15124 /* True if the 1st OR 2nd arguments are nonnegative. */
15126 strict_overflow_p)
15128 strict_overflow_p)));
15131 /* True if the 1st AND 2nd arguments are nonnegative. */
15133 strict_overflow_p)
15135 strict_overflow_p)));
15138 /* True if the 2nd argument is nonnegative. */
15140 strict_overflow_p);
15143 /* True if the 1st argument is nonnegative or the second
15144 argument is an even integer. */
15149 strict_overflow_p);
15152 /* True if the 1st argument is nonnegative or the second
15153 argument is an even integer valued real. */
15155 {
15156 REAL_VALUE_TYPE c;
15157 HOST_WIDE_INT n;
15162 {
15163 REAL_VALUE_TYPE cint;
15168 }
15169 }
15171 strict_overflow_p);
15175 }
15177 type);
15178 }
15180 /* Return true if T is known to be non-negative. If the return
15181 value is based on the assumption that signed overflow is undefined,
15182 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15183 *STRICT_OVERFLOW_P. */
15185 bool
15187 {
15193 {
15195 {
15199 /* If the initializer is non-void, then it's a normal expression
15200 that will be assigned to the slot. */
15204 /* Otherwise, the initializer sets the slot in some way. One common
15205 way is an assignment statement at the end of the initializer. */
15207 {
15215 else
15217 }
15221 strict_overflow_p);
15224 }
15227 {
15233 arg0,
15234 arg1,
15235 strict_overflow_p);
15236 }
15240 strict_overflow_p);
15243 strict_overflow_p);
15246 strict_overflow_p);
15251 }
15253 /* We don't know sign of `t', so be conservative and return false. */
15255 }
15257 /* Return true if T is known to be non-negative. If the return
15258 value is based on the assumption that signed overflow is undefined,
15259 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15260 *STRICT_OVERFLOW_P. */
15262 bool
15264 {
15271 {
15278 strict_overflow_p);
15284 strict_overflow_p);
15293 }
15296 {
15304 strict_overflow_p);
15309 strict_overflow_p);
15322 }
15323 }
15325 /* Return true if `t' is known to be non-negative. Handle warnings
15326 about undefined signed overflow. */
15328 bool
15330 {
15337 "determining that expression is always "
15339 WARN_STRICT_OVERFLOW_MISC);
15341 }
15344 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15345 For floating point we further ensure that T is not denormal.
15346 Similar logic is present in nonzero_address in rtlanal.h.
15348 If the return value is based on the assumption that signed overflow
15349 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15350 change *STRICT_OVERFLOW_P. */
15352 bool
15355 {
15357 {
15360 strict_overflow_p);
15363 {
15369 strict_overflow_p));
15370 }
15375 strict_overflow_p);
15379 }
15382 }
15384 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15385 For floating point we further ensure that T is not denormal.
15386 Similar logic is present in nonzero_address in rtlanal.h.
15388 If the return value is based on the assumption that signed overflow
15389 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15390 change *STRICT_OVERFLOW_P. */
15392 bool
15394 tree type,
15395 tree op0,
15397 {
15400 {
15404 {
15405 /* With the presence of negative values it is hard
15406 to say something. */
15413 /* One of operands must be positive and the other non-negative. */
15414 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15415 overflows, on a twos-complement machine the sum of two
15416 nonnegative numbers can never be zero. */
15418 strict_overflow_p)
15420 strict_overflow_p));
15421 }
15426 {
15428 strict_overflow_p)
15430 strict_overflow_p))
15431 {
15434 }
15435 }
15444 {
15447 }
15454 {
15458 /* When both operands are nonzero, then MAX must be too. */
15460 strict_overflow_p))
15463 /* MAX where operand 0 is positive is positive. */
15465 strict_overflow_p);
15466 }
15467 /* MAX where operand 1 is positive is positive. */
15472 {
15476 }
15481 strict_overflow_p)
15483 strict_overflow_p));
15487 }
15490 }
15492 /* Return true when T is an address and is known to be nonzero.
15493 For floating point we further ensure that T is not denormal.
15494 Similar logic is present in nonzero_address in rtlanal.h.
15496 If the return value is based on the assumption that signed overflow
15497 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15498 change *STRICT_OVERFLOW_P. */
15500 bool
15502 {
15505 {
15510 {
15516 /* Weak declarations may link to NULL. Other things may also be NULL
15517 so protect with -fdelete-null-pointer-checks; but not variables
15518 allocated on the stack. */
15520 && (flag_delete_null_pointer_checks
15524 /* Constants are never weak. */
15529 }
15537 {
15541 }
15546 }
15548 }
15550 /* Return true when T is an address and is known to be nonzero.
15551 For floating point we further ensure that T is not denormal.
15552 Similar logic is present in nonzero_address in rtlanal.h.
15554 If the return value is based on the assumption that signed overflow
15555 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15556 change *STRICT_OVERFLOW_P. */
15558 bool
15560 {
15564 /* Doing something useful for floating point would need more work. */
15570 {
15573 strict_overflow_p);
15579 strict_overflow_p);
15587 }
15590 {
15593 strict_overflow_p);
15601 strict_overflow_p);
15616 strict_overflow_p);
15620 strict_overflow_p);
15627 }
15629 }
15631 /* Return true when T is an address and is known to be nonzero.
15632 Handle warnings about undefined signed overflow. */
15634 bool
15636 {
15643 "determining that expression is always "
15645 WARN_STRICT_OVERFLOW_MISC);
15647 }
15649 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15650 attempt to fold the expression to a constant without modifying TYPE,
15651 OP0 or OP1.
15653 If the expression could be simplified to a constant, then return
15654 the constant. If the expression would not be simplified to a
15655 constant, then return NULL_TREE. */
15657 tree
15659 {
15662 }
15664 /* Given the components of a unary expression CODE, TYPE and OP0,
15665 attempt to fold the expression to a constant without modifying
15666 TYPE or OP0.
15668 If the expression could be simplified to a constant, then return
15669 the constant. If the expression would not be simplified to a
15670 constant, then return NULL_TREE. */
15672 tree
15674 {
15677 }
15679 /* If EXP represents referencing an element in a constant string
15680 (either via pointer arithmetic or array indexing), return the
15681 tree representing the value accessed, otherwise return NULL. */
15683 tree
15685 {
15689 {
15691 tree index;
15692 tree string;
15697 else
15698 {
15702 /* Optimize the special-case of a zero lower bound.
15704 We convert the low_bound to sizetype to avoid some problems
15705 with constant folding. (E.g. suppose the lower bound is 1,
15706 and its mode is QI. Without the conversion,l (ARRAY
15707 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15708 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15714 }
15727 }
15729 }
15731 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15732 an integer constant, real, or fixed-point constant.
15734 TYPE is the type of the result. */
15736 static tree
15738 {
15742 {
15744 {
15746 HOST_WIDE_INT high;
15754 }
15761 {
15762 FIXED_VALUE_TYPE f;
15767 /* Propagate overflow flags. */
15771 }
15775 }
15778 }
15780 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15781 an integer constant or real constant.
15783 TYPE is the type of the result. */
15785 tree
15787 {
15791 {
15793 /* If the value is unsigned, then the absolute value is
15794 the same as the ordinary value. */
15797 /* Similarly, if the value is non-negative. */
15800 /* If the value is negative, then the absolute value is
15801 its negation. */
15802 else
15803 {
15805 HOST_WIDE_INT high;
15811 }
15817 else
15823 }
15826 }
15828 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15829 constant. TYPE is the type of the result. */
15831 static tree
15833 {
15843 }
15845 /* Given CODE, a relational operator, the target type, TYPE and two
15846 constant operands OP0 and OP1, return the result of the
15847 relational operation. If the result is not a compile time
15848 constant, then return NULL_TREE. */
15850 static tree
15852 {
15855 /* From here on, the only cases we handle are when the result is
15856 known to be a constant. */
15859 {
15863 /* Handle the cases where either operand is a NaN. */
15865 {
15867 {
15895 }
15898 }
15901 }
15904 {
15908 }
15910 /* Handle equality/inequality of complex constants. */
15912 {
15923 else
15925 }
15927 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15929 To compute GT, swap the arguments and do LT.
15930 To compute GE, do LT and invert the result.
15931 To compute LE, swap the arguments, do LT and invert the result.
15932 To compute NE, do EQ and invert the result.
15934 Therefore, the code below must handle only EQ and LT. */
15937 {
15942 }
15944 /* Note that it is safe to invert for real values here because we
15945 have already handled the one case that it matters. */
15949 {
15952 }
15954 /* Compute a result for LT or EQ if args permit;
15955 Otherwise return T. */
15957 {
15962 else
15964 }
15965 else
15971 }
15973 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15974 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15975 itself. */
15977 tree
15979 {
15980 /* If the expression does not have side effects then we don't have to wrap
15981 it with a cleanup point expression. */
15985 /* If the expression is a return, check to see if the expression inside the
15986 return has no side effects or the right hand side of the modify expression
15987 inside the return. If either don't have side effects set we don't need to
15988 wrap the expression in a cleanup point expression. Note we don't check the
15989 left hand side of the modify because it should always be a return decl. */
15991 {
15998 }
16001 }
16003 /* Given a pointer value OP0 and a type TYPE, return a simplified version
16004 of an indirection through OP0, or NULL_TREE if no simplification is
16005 possible. */
16007 tree
16009 {
16011 tree subtype;
16019 {
16022 /* *&CONST_DECL -> to the value of the const decl. */
16025 /* *&p => p; make sure to handle *&"str"[cst] here. */
16027 {
16031 else
16033 }
16034 /* *(foo *)&fooarray => fooarray[0] */
16037 {
16045 }
16046 /* *(foo *)&complexfoo => __real__ complexfoo */
16050 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16053 {
16057 }
16058 }
16060 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16063 {
16066 tree op00type;
16073 {
16085 }
16086 }
16089 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16092 {
16095 tree op00type;
16102 {
16107 }
16108 }
16110 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16113 {
16114 tree type_domain;
16123 }
16126 }
16128 /* Builds an expression for an indirection through T, simplifying some
16129 cases. */
16131 tree
16133 {
16143 }
16145 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16147 tree
16149 {
16154 else
16156 }
16158 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16159 whose result is ignored. The type of the returned tree need not be
16160 the same as the original expression. */
16162 tree
16164 {
16170 {
16181 else
16187 {
16203 }
16208 }
16209 }
16211 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
16212 This can only be applied to objects of a sizetype. */
16214 tree
16216 {
16223 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16224 have to do anything. Only do this when we are not given a const,
16225 because in that case, this check is more expensive than just
16226 doing it. */
16228 {
16233 }
16235 /* If divisor is a power of two, simplify this to bit manipulation. */
16237 {
16239 {
16252 {
16253 high++;
16256 }
16260 }
16261 else
16262 {
16263 tree t;
16269 }
16270 }
16271 else
16272 {
16277 }
16280 }
16282 /* Likewise, but round down. */
16284 tree
16286 {
16293 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16294 have to do anything. Only do this when we are not given a const,
16295 because in that case, this check is more expensive than just
16296 doing it. */
16298 {
16303 }
16305 /* If divisor is a power of two, simplify this to bit manipulation. */
16307 {
16308 tree t;
16312 }
16313 else
16314 {
16319 }
16322 }
16324 /* Returns the pointer to the base of the object addressed by EXP and
16325 extracts the information about the offset of the access, storing it
16326 to PBITPOS and POFFSET. */
16328 static tree
16331 {
16332 tree core;
16335 HOST_WIDE_INT bitsize;
16339 {
16344 }
16345 else
16346 {
16350 }
16353 }
16355 /* Returns true if addresses of E1 and E2 differ by a constant, false
16356 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16358 bool
16360 {
16374 {
16384 }
16386 {
16387 /* If only one of the offsets is non-constant, the difference cannot
16388 be a constant. */
16390 }
16391 else
16396 }
16398 /* Simplify the floating point expression EXP when the sign of the
16399 result is not significant. Return NULL_TREE if no simplification
16400 is possible. */
16402 tree
16404 {
16409 {
16445 {
16448 {
16450 /* Strip copysign function call, return the 1st argument. */
16456 /* Strip sign ops from the argument of "odd" math functions. */
16458 {
16462 }
16464 }
16465 }
16470 }
16472 }