| blob | 40a580e77a65dfbae8f3277b794e339047b6360c |
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 {
889 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
890 &obj[some_exotic_number]. */
892 {
896 type);
897 }
898 else
909 }
910 \f
911 /* This is nonzero if we should defer warnings about undefined
912 overflow. This facility exists because these warnings are a
913 special case. The code to estimate loop iterations does not want
914 to issue any warnings, since it works with expressions which do not
915 occur in user code. Various bits of cleanup code call fold(), but
916 only use the result if it has certain characteristics (e.g., is a
917 constant); that code only wants to issue a warning if the result is
918 used. */
922 /* If a warning about undefined overflow is deferred, this is the
923 warning. Note that this may cause us to turn two warnings into
924 one, but that is fine since it is sufficient to only give one
925 warning per expression. */
929 /* If a warning about undefined overflow is deferred, this is the
930 level at which the warning should be emitted. */
934 /* Start deferring overflow warnings. We could use a stack here to
935 permit nested calls, but at present it is not necessary. */
937 void
939 {
941 }
943 /* Stop deferring overflow warnings. If there is a pending warning,
944 and ISSUE is true, then issue the warning if appropriate. STMT is
945 the statement with which the warning should be associated (used for
946 location information); STMT may be NULL. CODE is the level of the
947 warning--a warn_strict_overflow_code value. This function will use
948 the smaller of CODE and the deferred code when deciding whether to
949 issue the warning. CODE may be zero to mean to always use the
950 deferred code. */
952 void
954 {
956 location_t locus;
961 {
967 }
978 /* Use the smallest code level when deciding to issue the
979 warning. */
988 else
991 }
993 /* Stop deferring overflow warnings, ignoring any deferred
994 warnings. */
996 void
998 {
1000 }
1002 /* Whether we are deferring overflow warnings. */
1004 bool
1006 {
1008 }
1010 /* This is called when we fold something based on the fact that signed
1011 overflow is undefined. */
1013 static void
1015 {
1017 {
1020 {
1023 }
1024 }
1027 }
1028 \f
1029 /* Return true if the built-in mathematical function specified by CODE
1030 is odd, i.e. -f(x) == f(-x). */
1032 static bool
1034 {
1036 {
1070 }
1072 }
1074 /* Check whether we may negate an integer constant T without causing
1075 overflow. */
1077 bool
1079 {
1082 tree type;
1092 {
1097 }
1098 else
1103 }
1105 /* Determine whether an expression T can be cheaply negated using
1106 the function negate_expr without introducing undefined overflow. */
1108 static bool
1110 {
1111 tree type;
1120 {
1125 /* Check that -CST will not overflow type. */
1151 /* -(A + B) -> (-B) - A. */
1156 /* -(A + B) -> (-A) - B. */
1160 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1170 /* Fall through. */
1183 /* In general we can't negate A / B, because if A is INT_MIN and
1184 B is 1, we may turn this into INT_MIN / -1 which is undefined
1185 and actually traps on some architectures. But if overflow is
1186 undefined, we can negate, because - (INT_MIN / 1) is an
1187 overflow. */
1195 /* Negate -((double)float) as (double)(-float). */
1197 {
1201 }
1205 /* Negate -f(x) as f(-x). */
1211 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1213 {
1219 }
1224 }
1226 }
1228 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1229 simplification is possible.
1230 If negate_expr_p would return true for T, NULL_TREE will never be
1231 returned. */
1233 static tree
1235 {
1237 tree tem;
1240 {
1241 /* Convert - (~A) to A + 1. */
1257 /* Two's complement FP formats, such as c4x, may overflow. */
1267 {
1276 }
1298 {
1299 /* -(A + B) -> (-B) - A. */
1303 {
1307 }
1309 /* -(A + B) -> (-A) - B. */
1311 {
1315 }
1316 }
1320 /* - (A - B) -> B - A */
1332 /* Fall through. */
1336 {
1345 }
1353 /* In general we can't negate A / B, because if A is INT_MIN and
1354 B is 1, we may turn this into INT_MIN / -1 which is undefined
1355 and actually traps on some architectures. But if overflow is
1356 undefined, we can negate, because - (INT_MIN / 1) is an
1357 overflow. */
1359 {
1364 {
1371 }
1374 {
1381 }
1382 }
1386 /* Convert -((double)float) into (double)(-float). */
1388 {
1392 }
1396 /* Negate -f(x) as f(-x). */
1399 {
1405 }
1409 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1411 {
1416 {
1423 }
1424 }
1429 }
1432 }
1434 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1435 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1436 return NULL_TREE. */
1438 static tree
1440 {
1442 location_t loc;
1453 {
1456 }
1458 }
1459 \f
1460 /* Split a tree IN into a constant, literal and variable parts that could be
1461 combined with CODE to make IN. "constant" means an expression with
1462 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1463 commutative arithmetic operation. Store the constant part into *CONP,
1464 the literal in *LITP and return the variable part. If a part isn't
1465 present, set it to null. If the tree does not decompose in this way,
1466 return the entire tree as the variable part and the other parts as null.
1468 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1469 case, we negate an operand that was subtracted. Except if it is a
1470 literal for which we use *MINUS_LITP instead.
1472 If NEGATE_P is true, we are negating all of IN, again except a literal
1473 for which we use *MINUS_LITP instead.
1475 If IN is itself a literal or constant, return it as appropriate.
1477 Note that we do not guarantee that any of the three values will be the
1478 same type as IN, but they will have the same signedness and mode. */
1480 static tree
1483 {
1490 /* Strip any conversions that don't change the machine mode or signedness. */
1499 /* We can associate addition and subtraction together (even
1500 though the C standard doesn't say so) for integers because
1501 the value is not affected. For reals, the value might be
1502 affected, so we can't. */
1505 {
1511 /* First see if either of the operands is a literal, then a constant. */
1524 /* If we haven't dealt with either operand, this is not a case we can
1525 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1530 else
1533 /* Now do any needed negations. */
1540 }
1543 else
1547 {
1554 }
1557 }
1559 /* Re-associate trees split by the above function. T1 and T2 are
1560 either expressions to associate or null. Return the new
1561 expression, if any. LOC is the location of the new expression. If
1562 we build an operation, do it in TYPE and with CODE. */
1564 static tree
1566 {
1567 tree tem;
1574 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1575 try to fold this since we will have infinite recursion. But do
1576 deal with any NEGATE_EXPRs. */
1579 {
1581 {
1590 }
1592 {
1595 }
1600 }
1604 associate_trees_exit:
1607 }
1608 \f
1609 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1610 for use in int_const_binop, size_binop and size_diffop. */
1612 static bool
1614 {
1621 {
1630 }
1635 }
1638 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1639 to produce a new constant. Return NULL_TREE if we don't know how
1640 to evaluate CODE at compile-time.
1642 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1644 tree
1646 {
1650 HOST_WIDE_INT hi;
1652 HOST_WIDE_INT garbageh;
1653 tree t;
1656 int is_sizetype
1666 {
1682 /* It's unclear from the C standard whether shifts can overflow.
1683 The following code ignores overflow; perhaps a C standard
1684 interpretation ruling is needed. */
1713 /* This is a shortcut for a common special case. */
1718 {
1724 }
1726 /* ... fall through ... */
1732 {
1735 }
1738 {
1741 }
1748 /* This is a shortcut for a common special case. */
1753 {
1758 }
1760 /* ... fall through ... */
1778 else
1784 else
1790 }
1793 {
1796 /* Propagate overflow flags ourselves. */
1799 {
1802 }
1803 }
1804 else
1810 }
1812 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1813 constant. We assume ARG1 and ARG2 have the same data type, or at least
1814 are the same kind of constant and the same machine mode. Return zero if
1815 combining the constants is not allowed in the current operating mode.
1817 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1819 static tree
1821 {
1822 /* Sanity check for the recursive cases. */
1833 {
1835 REAL_VALUE_TYPE d1;
1836 REAL_VALUE_TYPE d2;
1837 REAL_VALUE_TYPE value;
1838 REAL_VALUE_TYPE result;
1842 /* The following codes are handled by real_arithmetic. */
1844 {
1855 }
1863 /* Don't perform operation if we honor signaling NaNs and
1864 either operand is a NaN. */
1869 /* Don't perform operation if it would raise a division
1870 by zero exception. */
1876 /* If either operand is a NaN, just return it. Otherwise, set up
1877 for floating-point trap; we return an overflow. */
1886 /* Don't constant fold this floating point operation if
1887 the result has overflowed and flag_trapping_math. */
1895 /* Don't constant fold this floating point operation if the
1896 result may dependent upon the run-time rounding mode and
1897 flag_rounding_math is set, or if GCC's software emulation
1898 is unable to accurately represent the result. */
1908 }
1911 {
1912 FIXED_VALUE_TYPE f1;
1913 FIXED_VALUE_TYPE f2;
1914 FIXED_VALUE_TYPE result;
1919 /* The following codes are handled by fixed_arithmetic. */
1921 {
1938 }
1945 /* Propagate overflow flags. */
1949 }
1952 {
1961 {
1969 #ifdef HAVE_mpc
1973 mpc_mul);
1974 #endif
1979 notrunc);
1983 notrunc);
1987 #ifdef HAVE_mpc
1991 mpc_div);
1992 /* Fallthru ... */
1993 #endif
2000 {
2001 /* Keep this algorithm in sync with
2002 tree-complex.c:expand_complex_div_straight().
2004 Expand complex division to scalars, straightforward algorithm.
2005 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
2006 t = br*br + bi*bi
2007 */
2008 tree magsquared
2012 notrunc);
2013 tree t1
2017 notrunc);
2018 tree t2
2022 notrunc);
2026 }
2027 else
2028 {
2029 /* Keep this algorithm in sync with
2030 tree-complex.c:expand_complex_div_wide().
2032 Expand complex division to scalars, modified algorithm to minimize
2033 overflow with wide input ranges. */
2039 {
2040 /* In the TRUE branch, we compute
2041 ratio = br/bi;
2042 div = (br * ratio) + bi;
2043 tr = (ar * ratio) + ai;
2044 ti = (ai * ratio) - ar;
2045 tr = tr / div;
2046 ti = ti / div; */
2050 notrunc),
2051 notrunc);
2059 }
2060 else
2061 {
2062 /* In the FALSE branch, we compute
2063 ratio = d/c;
2064 divisor = (d * ratio) + c;
2065 tr = (b * ratio) + a;
2066 ti = b - (a * ratio);
2067 tr = tr / div;
2068 ti = ti / div; */
2072 notrunc),
2073 notrunc);
2082 }
2083 }
2088 }
2092 }
2095 {
2107 {
2110 /* The trailing elements can be empty and should be treated as 0 */
2113 else
2114 {
2117 }
2121 else
2122 {
2125 }
2129 /* It is possible that const_binop cannot handle the given
2130 code and return NULL_TREE */
2135 }
2137 }
2139 }
2141 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2142 indicates which particular sizetype to create. */
2144 tree
2146 {
2148 }
2149 \f
2150 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2151 is a tree code. The type of the result is taken from the operands.
2152 Both must be equivalent integer types, ala int_binop_types_match_p.
2153 If the operands are constant, so is the result. */
2155 tree
2157 {
2166 /* Handle the special case of two integer constants faster. */
2168 {
2169 /* And some specific cases even faster than that. */
2171 {
2176 }
2178 {
2181 }
2183 {
2186 }
2188 /* Handle general case of two integer constants. */
2190 }
2193 }
2195 /* Given two values, either both of sizetype or both of bitsizetype,
2196 compute the difference between the two values. Return the value
2197 in signed type corresponding to the type of the operands. */
2199 tree
2201 {
2203 tree ctype;
2208 /* If the type is already signed, just do the simple thing. */
2216 else
2219 /* If either operand is not a constant, do the conversions to the signed
2220 type and subtract. The hardware will do the right thing with any
2221 overflow in the subtraction. */
2227 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2228 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2229 overflow) and negate (which can't either). Special-case a result
2230 of zero while we're here. */
2236 else
2240 MINUS_EXPR,
2242 }
2243 \f
2244 /* A subroutine of fold_convert_const handling conversions of an
2245 INTEGER_CST to another integer type. */
2247 static tree
2249 {
2250 tree t;
2252 /* Given an integer constant, make new constant with new type,
2253 appropriately sign-extended or truncated. */
2256 /* Don't set the overflow when
2257 converting from a pointer, */
2259 /* or to a sizetype with same signedness
2260 and the precision is unchanged.
2261 ??? sizetype is always sign-extended,
2262 but its signedness depends on the
2263 frontend. Thus we see spurious overflows
2264 here if we do not check this. */
2279 }
2281 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2282 to an integer type. */
2284 static tree
2286 {
2288 tree t;
2290 /* The following code implements the floating point to integer
2291 conversion rules required by the Java Language Specification,
2292 that IEEE NaNs are mapped to zero and values that overflow
2293 the target precision saturate, i.e. values greater than
2294 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2295 are mapped to INT_MIN. These semantics are allowed by the
2296 C and C++ standards that simply state that the behavior of
2297 FP-to-integer conversion is unspecified upon overflow. */
2300 REAL_VALUE_TYPE r;
2304 {
2311 }
2313 /* If R is NaN, return zero and show we have an overflow. */
2315 {
2319 }
2321 /* See if R is less than the lower bound or greater than the
2322 upper bound. */
2325 {
2329 {
2333 }
2334 }
2337 {
2340 {
2343 {
2347 }
2348 }
2349 }
2357 }
2359 /* A subroutine of fold_convert_const handling conversions of a
2360 FIXED_CST to an integer type. */
2362 static tree
2364 {
2365 tree t;
2369 /* Right shift FIXED_CST to temp by fbit. */
2373 {
2378 /* Left shift temp to temp_trunc by fbit. */
2383 }
2384 else
2385 {
2390 }
2392 /* If FIXED_CST is negative, we need to round the value toward 0.
2393 By checking if the fractional bits are not zero to add 1 to temp. */
2396 {
2397 double_int one;
2401 }
2403 /* Given a fixed-point constant, make new constant with new type,
2404 appropriately sign-extended or truncated. */
2412 }
2414 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2415 to another floating point type. */
2417 static tree
2419 {
2420 REAL_VALUE_TYPE value;
2421 tree t;
2426 /* If converting an infinity or NAN to a representation that doesn't
2427 have one, set the overflow bit so that we can produce some kind of
2428 error message at the appropriate point if necessary. It's not the
2429 most user-friendly message, but it's better than nothing. */
2436 /* Regular overflow, conversion produced an infinity in a mode that
2437 can't represent them. */
2442 else
2445 }
2447 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2448 to a floating point type. */
2450 static tree
2452 {
2453 REAL_VALUE_TYPE value;
2454 tree t;
2461 }
2463 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2464 to another fixed-point type. */
2466 static tree
2468 {
2469 FIXED_VALUE_TYPE value;
2470 tree t;
2477 /* Propagate overflow flags. */
2481 }
2483 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2484 to a fixed-point type. */
2486 static tree
2488 {
2489 FIXED_VALUE_TYPE value;
2490 tree t;
2499 /* Propagate overflow flags. */
2503 }
2505 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2506 to a fixed-point type. */
2508 static tree
2510 {
2511 FIXED_VALUE_TYPE value;
2512 tree t;
2520 /* Propagate overflow flags. */
2524 }
2526 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2527 type TYPE. If no simplification can be done return NULL_TREE. */
2529 static tree
2531 {
2537 {
2544 }
2546 {
2553 }
2555 {
2562 }
2564 }
2566 /* Construct a vector of zero elements of vector type TYPE. */
2568 static tree
2570 {
2581 }
2583 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2585 bool
2587 {
2602 {
2621 }
2622 }
2624 /* Convert expression ARG to type TYPE. Used by the middle-end for
2625 simple conversions in preference to calling the front-end's convert. */
2627 tree
2629 {
2631 tree tem;
2645 {
2648 /* Handle conversions between pointers to different address spaces. */
2653 /* fall through */
2658 {
2662 }
2676 {
2680 }
2682 {
2686 }
2688 {
2692 }
2695 {
2713 }
2718 {
2722 }
2725 {
2739 }
2743 {
2752 integer_zero_node));
2754 {
2758 {
2764 }
2772 }
2776 }
2794 }
2795 fold_convert_exit:
2798 }
2799 \f
2800 /* Return false if expr can be assumed not to be an lvalue, true
2801 otherwise. */
2803 static bool
2805 {
2806 /* We only need to wrap lvalue tree codes. */
2808 {
2840 /* Assume the worst for front-end tree codes. */
2844 }
2847 }
2849 /* Return an expr equal to X but certainly not valid as an lvalue. */
2851 tree
2853 {
2854 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2855 us. */
2864 }
2866 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2867 Zero means allow extended lvalues. */
2871 /* When pedantic, return an expr equal to X but certainly not valid as a
2872 pedantic lvalue. Otherwise, return X. */
2874 static tree
2876 {
2881 }
2882 \f
2883 /* Given a tree comparison code, return the code that is the logical inverse
2884 of the given code. It is not safe to do this for floating-point
2885 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2886 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2888 enum tree_code
2890 {
2895 {
2926 }
2927 }
2929 /* Similar, but return the comparison that results if the operands are
2930 swapped. This is safe for floating-point. */
2932 enum tree_code
2934 {
2936 {
2962 }
2963 }
2966 /* Convert a comparison tree code from an enum tree_code representation
2967 into a compcode bit-based encoding. This function is the inverse of
2968 compcode_to_comparison. */
2970 static enum comparison_code
2972 {
2974 {
3005 }
3006 }
3008 /* Convert a compcode bit-based encoding of a comparison operator back
3009 to GCC's enum tree_code representation. This function is the
3010 inverse of comparison_to_compcode. */
3012 static enum tree_code
3014 {
3016 {
3047 }
3048 }
3050 /* Return a tree for the comparison which is the combination of
3051 doing the AND or OR (depending on CODE) of the two operations LCODE
3052 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
3053 the possibility of trapping if the mode has NaNs, and return NULL_TREE
3054 if this makes the transformation invalid. */
3056 tree
3061 {
3068 {
3079 }
3082 {
3083 /* Eliminate unordered comparisons, as well as LTGT and ORD
3084 which are not used unless the mode has NaNs. */
3090 }
3092 {
3093 /* Check that the original operation and the optimized ones will trap
3094 under the same condition. */
3105 /* In a short-circuited boolean expression the LHS might be
3106 such that the RHS, if evaluated, will never trap. For
3107 example, in ORD (x, y) && (x < y), we evaluate the RHS only
3108 if neither x nor y is NaN. (This is a mixed blessing: for
3109 example, the expression above will never trap, hence
3110 optimizing it to x < y would be invalid). */
3115 /* If the comparison was short-circuited, and only the RHS
3116 trapped, we may now generate a spurious trap. */
3121 /* If we changed the conditions that cause a trap, we lose. */
3124 }
3130 else
3131 {
3136 }
3137 }
3138 \f
3139 /* Return nonzero if two operands (typically of the same tree node)
3140 are necessarily equal. If either argument has side-effects this
3141 function returns zero. FLAGS modifies behavior as follows:
3143 If OEP_ONLY_CONST is set, only return nonzero for constants.
3144 This function tests whether the operands are indistinguishable;
3145 it does not test whether they are equal using C's == operation.
3146 The distinction is important for IEEE floating point, because
3147 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3148 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3150 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3151 even though it may hold multiple values during a function.
3152 This is because a GCC tree node guarantees that nothing else is
3153 executed between the evaluation of its "operands" (which may often
3154 be evaluated in arbitrary order). Hence if the operands themselves
3155 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3156 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3157 unset means assuming isochronic (or instantaneous) tree equivalence.
3158 Unless comparing arbitrary expression trees, such as from different
3159 statements, this flag can usually be left unset.
3161 If OEP_PURE_SAME is set, then pure functions with identical arguments
3162 are considered the same. It is used when the caller has other ways
3163 to ensure that global memory is unchanged in between. */
3165 int
3167 {
3168 /* If either is ERROR_MARK, they aren't equal. */
3172 /* Check equality of integer constants before bailing out due to
3173 precision differences. */
3177 /* If both types don't have the same signedness, then we can't consider
3178 them equal. We must check this before the STRIP_NOPS calls
3179 because they may change the signedness of the arguments. As pointers
3180 strictly don't have a signedness, require either two pointers or
3181 two non-pointers as well. */
3186 /* We cannot consider pointers to different address space equal. */
3192 /* If both types don't have the same precision, then it is not safe
3193 to strip NOPs. */
3200 /* In case both args are comparisons but with different comparison
3201 code, try to swap the comparison operands of one arg to produce
3202 a match and compare that variant. */
3206 {
3214 }
3217 /* This is needed for conversions and for COMPONENT_REF.
3218 Might as well play it safe and always test this. */
3224 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3225 We don't care about side effects in that case because the SAVE_EXPR
3226 takes care of that for us. In all other cases, two expressions are
3227 equal if they have no side effects. If we have two identical
3228 expressions with side effects that should be treated the same due
3229 to the only side effects being identical SAVE_EXPR's, that will
3230 be detected in the recursive calls below. */
3236 /* Next handle constant cases, those for which we can return 1 even
3237 if ONLY_CONST is set. */
3240 {
3255 {
3256 /* If we do not distinguish between signed and unsigned zero,
3257 consider them equal. */
3260 }
3264 {
3270 {
3272 flags))
3276 }
3279 }
3283 flags)
3285 flags));
3298 }
3303 /* Define macros to test an operand from arg0 and arg1 for equality and a
3304 variant that allows null and views null as being different from any
3305 non-null value. In the latter case, if either is null, the both
3306 must be; otherwise, do the normal comparison. */
3307 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3308 TREE_OPERAND (arg1, N), flags)
3310 #define OP_SAME_WITH_NULL(N) \
3311 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3312 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3315 {
3317 /* Two conversions are equal only if signedness and modes match. */
3319 {
3320 CASE_CONVERT:
3328 }
3338 /* For commutative ops, allow the other order. */
3346 /* If either of the pointer (or reference) expressions we are
3347 dereferencing contain a side effect, these cannot be equal. */
3353 {
3363 /* Operands 2 and 3 may be null.
3364 Compare the array index by value if it is constant first as we
3365 may have different types but same value here. */
3374 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3375 may be NULL when we're called to compare MEM_EXPRs. */
3385 }
3389 {
3404 /* Otherwise take into account this is a commutative operation. */
3415 }
3419 {
3421 /* If the CALL_EXPRs call different functions, then they
3422 clearly can not be equal. */
3424 flags))
3427 {
3431 else
3435 }
3437 /* Now see if all the arguments are the same. */
3438 {
3449 /* If we get here and both argument lists are exhausted
3450 then the CALL_EXPRs are equal. */
3452 }
3455 }
3458 /* Consider __builtin_sqrt equal to sqrt. */
3466 }
3468 #undef OP_SAME
3469 #undef OP_SAME_WITH_NULL
3470 }
3471 \f
3472 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3473 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3475 When in doubt, return 0. */
3477 static int
3479 {
3491 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3492 and see if the inner values are the same. This removes any
3493 signedness comparison, which doesn't matter here. */
3500 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3501 actual comparison operand, ARG0.
3503 First throw away any conversions to wider types
3504 already present in the operands. */
3513 {
3516 /* Make sure shorter operand is extended the right way
3517 to match the longer operand. */
3523 }
3526 }
3527 \f
3528 /* See if ARG is an expression that is either a comparison or is performing
3529 arithmetic on comparisons. The comparisons must only be comparing
3530 two different values, which will be stored in *CVAL1 and *CVAL2; if
3531 they are nonzero it means that some operands have already been found.
3532 No variables may be used anywhere else in the expression except in the
3533 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3534 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3536 If this is true, return 1. Otherwise, return zero. */
3538 static int
3540 {
3544 /* We can handle some of the tcc_expression cases here. */
3554 {
3555 /* If we've already found a CVAL1 or CVAL2, this expression is
3556 two complex to handle. */
3562 }
3565 {
3588 /* First see if we can handle the first operand, then the second. For
3589 the second operand, we know *CVAL1 can't be zero. It must be that
3590 one side of the comparison is each of the values; test for the
3591 case where this isn't true by failing if the two operands
3592 are the same. */
3601 ;
3605 ;
3606 else
3610 ;
3614 ;
3615 else
3622 }
3623 }
3624 \f
3625 /* ARG is a tree that is known to contain just arithmetic operations and
3626 comparisons. Evaluate the operations in the tree substituting NEW0 for
3627 any occurrence of OLD0 as an operand of a comparison and likewise for
3628 NEW1 and OLD1. */
3630 static tree
3633 {
3638 /* We can handle some of the tcc_expression cases here. */
3646 {
3661 {
3680 }
3681 /* Fall through - ??? */
3684 {
3688 /* We need to check both for exact equality and tree equality. The
3689 former will be true if the operand has a side-effect. In that
3690 case, we know the operand occurred exactly once. */
3703 }
3707 }
3708 }
3709 \f
3710 /* Return a tree for the case when the result of an expression is RESULT
3711 converted to TYPE and OMITTED was previously an operand of the expression
3712 but is now not needed (e.g., we folded OMITTED * 0).
3714 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3715 the conversion of RESULT to TYPE. */
3717 tree
3719 {
3722 /* If the resulting operand is an empty statement, just return the omitted
3723 statement casted to void. */
3725 {
3728 }
3731 {
3734 }
3738 omit_one_operand_exit:
3741 }
3743 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3745 static tree
3747 tree omitted)
3748 {
3751 /* If the resulting operand is an empty statement, just return the omitted
3752 statement casted to void. */
3754 {
3757 }
3760 {
3763 }
3767 pedantic_omit_one_operand_exit:
3770 }
3772 /* Return a tree for the case when the result of an expression is RESULT
3773 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3774 of the expression but are now not needed.
3776 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3777 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3778 evaluated before OMITTED2. Otherwise, if neither has side effects,
3779 just do the conversion of RESULT to TYPE. */
3781 tree
3784 {
3788 {
3791 }
3793 {
3796 }
3799 }
3801 \f
3802 /* Return a simplified tree node for the truth-negation of ARG. This
3803 never alters ARG itself. We assume that ARG is an operation that
3804 returns a truth value (0 or 1).
3806 FIXME: one would think we would fold the result, but it causes
3807 problems with the dominator optimizer. */
3809 tree
3811 {
3816 /* If this is a comparison, we can simply invert it, except for
3817 floating-point non-equality comparisons, in which case we just
3818 enclose a TRUTH_NOT_EXPR around what we have. */
3821 {
3824 && flag_trapping_math
3836 }
3839 {
3868 /* Here we can invert either operand. We invert the first operand
3869 unless the second operand is a TRUTH_NOT_EXPR in which case our
3870 result is the XOR of the first operand with the inside of the
3871 negation of the second operand. */
3876 else
3910 {
3921 /* A COND_EXPR may have a throw as one operand, which
3922 then has void type. Just leave void operands
3923 as they are. */
3930 }
3947 CASE_CONVERT:
3949 {
3952 }
3954 /* ... fall through ... */
3985 }
3991 }
3993 /* Return a simplified tree node for the truth-negation of ARG. This
3994 never alters ARG itself. We assume that ARG is an operation that
3995 returns a truth value (0 or 1).
3997 FIXME: one would think we would fold the result, but it causes
3998 problems with the dominator optimizer. */
4000 tree
4002 {
4003 tree tem;
4010 {
4013 }
4016 }
4018 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
4019 operands are another bit-wise operation with a common input. If so,
4020 distribute the bit operations to save an operation and possibly two if
4021 constants are involved. For example, convert
4022 (A | B) & (A | C) into A | (B & C)
4023 Further simplification will occur if B and C are constants.
4025 If this optimization cannot be done, 0 will be returned. */
4027 static tree
4030 {
4031 tree common;
4041 {
4045 }
4047 {
4051 }
4053 {
4057 }
4059 {
4063 }
4064 else
4072 }
4074 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
4075 with code CODE. This optimization is unsafe. */
4076 static tree
4079 {
4083 /* (A / C) +- (B / C) -> (A +- B) / C. */
4093 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
4098 {
4110 }
4113 }
4114 \f
4115 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4116 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
4118 static tree
4121 {
4125 {
4132 }
4147 }
4149 /* Optimize a bit-field compare.
4151 There are two cases: First is a compare against a constant and the
4152 second is a comparison of two items where the fields are at the same
4153 bit position relative to the start of a chunk (byte, halfword, word)
4154 large enough to contain it. In these cases we can avoid the shift
4155 implicit in bitfield extractions.
4157 For constants, we emit a compare of the shifted constant with the
4158 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4159 compared. For two fields at the same position, we do the ANDs with the
4160 similar mask and compare the result of the ANDs.
4162 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4163 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4164 are the left and right operands of the comparison, respectively.
4166 If the optimization described above can be done, we return the resulting
4167 tree. Otherwise we return zero. */
4169 static tree
4172 {
4181 tree mask;
4182 tree offset;
4184 /* Get all the information about the extractions being done. If the bit size
4185 if the same as the size of the underlying object, we aren't doing an
4186 extraction at all and so can do nothing. We also don't want to
4187 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4188 then will no longer be able to replace it. */
4196 {
4197 /* If this is not a constant, we can only do something if bit positions,
4198 sizes, and signedness are the same. */
4206 }
4208 /* See if we can find a mode to refer to this field. We should be able to,
4209 but fail if we can't. */
4218 /* Set signed and unsigned types of the precision of this mode for the
4219 shifts below. */
4223 /* Compute the bit position and size for the new reference and our offset
4224 within it. If the new reference is the same size as the original, we
4225 won't optimize anything, so return zero. */
4235 /* Make the mask to be used against the extracted field. */
4242 /* If not comparing with constant, just rework the comparison
4243 and return. */
4247 unsigned_type,
4250 mask),
4253 unsigned_type,
4256 mask));
4258 /* Otherwise, we are handling the constant case. See if the constant is too
4259 big for the field. Warn and return a tree of for 0 (false) if so. We do
4260 this not only for its own sake, but to avoid having to test for this
4261 error case below. If we didn't, we might generate wrong code.
4263 For unsigned fields, the constant shifted right by the field length should
4264 be all zero. For signed fields, the high-order bits should agree with
4265 the sign bit. */
4268 {
4273 {
4277 }
4278 }
4279 else
4280 {
4285 {
4289 }
4290 }
4292 /* Single-bit compares should always be against zero. */
4294 {
4297 }
4299 /* Make a new bitfield reference, shift the constant over the
4300 appropriate number of bits and mask it with the computed mask
4301 (in case this was a signed field). If we changed it, make a new one. */
4304 {
4307 }
4317 rhs);
4320 }
4321 \f
4322 /* Subroutine for fold_truthop: decode a field reference.
4324 If EXP is a comparison reference, we return the innermost reference.
4326 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4327 set to the starting bit number.
4329 If the innermost field can be completely contained in a mode-sized
4330 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4332 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4333 otherwise it is not changed.
4335 *PUNSIGNEDP is set to the signedness of the field.
4337 *PMASK is set to the mask used. This is either contained in a
4338 BIT_AND_EXPR or derived from the width of the field.
4340 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4342 Return 0 if this is not a component reference or is one that we can't
4343 do anything with. */
4345 static tree
4350 {
4354 tree unsigned_type;
4357 /* All the optimizations using this function assume integer fields.
4358 There are problems with FP fields since the type_for_size call
4359 below can fail for, e.g., XFmode. */
4363 /* We are interested in the bare arrangement of bits, so strip everything
4364 that doesn't affect the machine mode. However, record the type of the
4365 outermost expression if it may matter below. */
4372 {
4378 }
4387 /* If the number of bits in the reference is the same as the bitsize of
4388 the outer type, then the outer type gives the signedness. Otherwise
4389 (in case of a small bitfield) the signedness is unchanged. */
4393 /* Compute the mask to access the bitfield. */
4402 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4410 }
4412 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4413 bit positions. */
4415 static int
4417 {
4420 tree tmask;
4424 return
4431 }
4433 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4434 represents the sign bit of EXP's type. If EXP represents a sign
4435 or zero extension, also test VAL against the unextended type.
4436 The return value is the (sub)expression whose sign bit is VAL,
4437 or NULL_TREE otherwise. */
4439 static tree
4441 {
4445 tree t;
4447 /* Tree EXP must have an integral type. */
4452 /* Tree VAL must be an integer constant. */
4459 {
4466 }
4467 else
4468 {
4475 }
4477 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4478 treat VAL as if it were unsigned. */
4483 /* Handle extension from a narrower type. */
4489 }
4491 /* Subroutine for fold_truthop: determine if an operand is simple enough
4492 to be evaluated unconditionally. */
4494 static int
4496 {
4497 /* Strip any conversions that don't change the machine mode. */
4506 /* Don't regard global variables as simple. They may be
4507 allocated in ways unknown to the compiler (shared memory,
4508 #pragma weak, etc). */
4511 /* Loading a static variable is unduly expensive, but global
4512 registers aren't expensive. */
4514 }
4515 \f
4516 /* The following functions are subroutines to fold_range_test and allow it to
4517 try to change a logical combination of comparisons into a range test.
4519 For example, both
4520 X == 2 || X == 3 || X == 4 || X == 5
4521 and
4522 X >= 2 && X <= 5
4523 are converted to
4524 (unsigned) (X - 2) <= 3
4526 We describe each set of comparisons as being either inside or outside
4527 a range, using a variable named like IN_P, and then describe the
4528 range with a lower and upper bound. If one of the bounds is omitted,
4529 it represents either the highest or lowest value of the type.
4531 In the comments below, we represent a range by two numbers in brackets
4532 preceded by a "+" to designate being inside that range, or a "-" to
4533 designate being outside that range, so the condition can be inverted by
4534 flipping the prefix. An omitted bound is represented by a "-". For
4535 example, "- [-, 10]" means being outside the range starting at the lowest
4536 possible value and ending at 10, in other words, being greater than 10.
4537 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4538 always false.
4540 We set up things so that the missing bounds are handled in a consistent
4541 manner so neither a missing bound nor "true" and "false" need to be
4542 handled using a special case. */
4544 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4545 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4546 and UPPER1_P are nonzero if the respective argument is an upper bound
4547 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4548 must be specified for a comparison. ARG1 will be converted to ARG0's
4549 type if both are specified. */
4551 static tree
4554 {
4555 tree tem;
4559 /* If neither arg represents infinity, do the normal operation.
4560 Else, if not a comparison, return infinity. Else handle the special
4561 comparison rules. Note that most of the cases below won't occur, but
4562 are handled for consistency. */
4565 {
4570 }
4575 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4576 for neither. In real maths, we cannot assume open ended ranges are
4577 the same. But, this is computer arithmetic, where numbers are finite.
4578 We can therefore make the transformation of any unbounded range with
4579 the value Z, Z being greater than any representable number. This permits
4580 us to treat unbounded ranges as equal. */
4584 {
4605 }
4608 }
4609 \f
4610 /* Given EXP, a logical expression, set the range it is testing into
4611 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4612 actually being tested. *PLOW and *PHIGH will be made of the same
4613 type as the returned expression. If EXP is not a comparison, we
4614 will most likely not be returning a useful value and range. Set
4615 *STRICT_OVERFLOW_P to true if the return value is only valid
4616 because signed overflow is undefined; otherwise, do not change
4617 *STRICT_OVERFLOW_P. */
4619 tree
4622 {
4630 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4631 and see if we can refine the range. Some of the cases below may not
4632 happen, but it doesn't seem worth worrying about this. We "continue"
4633 the outer loop when we've changed something; otherwise we "break"
4634 the switch, which will "break" the while. */
4640 {
4645 {
4657 }
4660 {
4667 /* We can only do something if the range is testing for zero
4668 and if the second operand is an integer constant. Note that
4669 saying something is "in" the range we make is done by
4670 complementing IN_P since it will set in the initial case of
4671 being not equal to zero; "out" is leaving it alone. */
4678 {
4699 }
4701 /* If this is an unsigned comparison, we also know that EXP is
4702 greater than or equal to zero. We base the range tests we make
4703 on that fact, so we record it here so we can parse existing
4704 range tests. We test arg0_type since often the return type
4705 of, e.g. EQ_EXPR, is boolean. */
4707 {
4711 NULL_TREE))
4716 /* If the high bound is missing, but we have a nonzero low
4717 bound, reverse the range so it goes from zero to the low bound
4718 minus 1. */
4720 {
4725 }
4726 }
4732 /* (-x) IN [a,b] -> x in [-b, -a] */
4744 /* ~ X -> -X - 1 */
4754 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4755 move a constant to the other side. */
4760 /* If EXP is signed, any overflow in the computation is undefined,
4761 so we don't worry about it so long as our computations on
4762 the bounds don't overflow. For unsigned, overflow is defined
4763 and this is exactly the right thing. */
4775 /* Check for an unsigned range which has wrapped around the maximum
4776 value thus making n_high < n_low, and normalize it. */
4778 {
4784 /* If the range is of the form +/- [ x+1, x ], we won't
4785 be able to normalize it. But then, it represents the
4786 whole range or the empty set, so make it
4787 +/- [ -, - ]. */
4791 else
4793 }
4794 else
4818 /* If we're converting arg0 from an unsigned type, to exp,
4819 a signed type, we will be doing the comparison as unsigned.
4820 The tests above have already verified that LOW and HIGH
4821 are both positive.
4823 So we have to ensure that we will handle large unsigned
4824 values the same way that the current signed bounds treat
4825 negative values. */
4828 {
4829 tree high_positive;
4830 tree equiv_type;
4831 /* For fixed-point modes, we need to pass the saturating flag
4832 as the 2nd parameter. */
4837 else
4841 /* A range without an upper bound is, naturally, unbounded.
4842 Since convert would have cropped a very large value, use
4843 the max value for the destination type. */
4844 high_positive
4851 high_positive),
4854 /* If the low bound is specified, "and" the range with the
4855 range for which the original unsigned value will be
4856 positive. */
4858 {
4862 integer_zero_node),
4863 high_positive))
4867 }
4868 else
4869 {
4870 /* Otherwise, "or" the range with the range of the input
4871 that will be interpreted as negative. */
4875 integer_zero_node),
4876 high_positive))
4880 }
4881 }
4889 }
4892 }
4894 /* If EXP is a constant, we can evaluate whether this is true or false. */
4896 {
4903 }
4907 }
4908 \f
4909 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4910 type, TYPE, return an expression to test if EXP is in (or out of, depending
4911 on IN_P) the range. Return 0 if the test couldn't be created. */
4913 tree
4916 {
4919 #ifdef HAVE_canonicalize_funcptr_for_compare
4920 /* Disable this optimization for function pointer expressions
4921 on targets that require function pointer canonicalization. */
4926 #endif
4929 {
4935 }
4953 {
4955 {
4959 }
4961 }
4963 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4965 {
4967 HOST_WIDE_INT hi;
4972 {
4975 }
4976 else
4977 {
4980 }
4983 {
4985 {
4988 etype
4990 else
4993 }
4996 }
4997 }
4999 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5000 This requires wrap-around arithmetics for the type of the expression.
5001 First make sure that arithmetics in this type is valid, then make sure
5002 that it wraps around. */
5008 {
5011 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5012 for the type in question, as we rely on this here. */
5022 else
5024 }
5034 {
5036 {
5043 }
5045 }
5053 }
5054 \f
5055 /* Return the predecessor of VAL in its type, handling the infinite case. */
5057 static tree
5059 {
5065 else
5067 }
5069 /* Return the successor of VAL in its type, handling the infinite case. */
5071 static tree
5073 {
5079 else
5081 }
5083 /* Given two ranges, see if we can merge them into one. Return 1 if we
5084 can, 0 if we can't. Set the output range into the specified parameters. */
5086 bool
5089 {
5093 tree tem;
5103 /* Make range 0 be the range that starts first, or ends last if they
5104 start at the same value. Swap them if it isn't. */
5107 || (lowequal
5110 {
5114 }
5116 /* Now flag two cases, whether the ranges are disjoint or whether the
5117 second range is totally subsumed in the first. Note that the tests
5118 below are simplified by the ones above. */
5124 /* We now have four cases, depending on whether we are including or
5125 excluding the two ranges. */
5127 {
5128 /* If they don't overlap, the result is false. If the second range
5129 is a subset it is the result. Otherwise, the range is from the start
5130 of the second to the end of the first. */
5135 else
5137 }
5140 {
5141 /* If they don't overlap, the result is the first range. If they are
5142 equal, the result is false. If the second range is a subset of the
5143 first, and the ranges begin at the same place, we go from just after
5144 the end of the second range to the end of the first. If the second
5145 range is not a subset of the first, or if it is a subset and both
5146 ranges end at the same place, the range starts at the start of the
5147 first range and ends just before the second range.
5148 Otherwise, we can't describe this as a single range. */
5154 {
5159 {
5160 /* We are in the weird situation where high0 > high1 but
5161 high1 has no successor. Punt. */
5163 }
5164 }
5166 {
5171 {
5172 /* low0 < low1 but low1 has no predecessor. Punt. */
5174 }
5175 }
5176 else
5178 }
5181 {
5182 /* If they don't overlap, the result is the second range. If the second
5183 is a subset of the first, the result is false. Otherwise,
5184 the range starts just after the first range and ends at the
5185 end of the second. */
5190 else
5191 {
5196 {
5197 /* high1 > high0 but high0 has no successor. Punt. */
5199 }
5200 }
5201 }
5203 else
5204 {
5205 /* The case where we are excluding both ranges. Here the complex case
5206 is if they don't overlap. In that case, the only time we have a
5207 range is if they are adjacent. If the second is a subset of the
5208 first, the result is the first. Otherwise, the range to exclude
5209 starts at the beginning of the first range and ends at the end of the
5210 second. */
5212 {
5217 else
5218 {
5219 /* Canonicalize - [min, x] into - [-, x]. */
5222 {
5227 /* FALLTHROUGH */
5240 }
5242 /* Canonicalize - [x, max] into - [x, -]. */
5245 {
5250 /* FALLTHROUGH */
5265 }
5267 /* The ranges might be also adjacent between the maximum and
5268 minimum values of the given type. For
5269 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5270 return + [x + 1, y - 1]. */
5272 {
5279 }
5280 else
5282 }
5283 }
5286 else
5288 }
5292 }
5293 \f
5295 /* Subroutine of fold, looking inside expressions of the form
5296 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5297 of the COND_EXPR. This function is being used also to optimize
5298 A op B ? C : A, by reversing the comparison first.
5300 Return a folded expression whose code is not a COND_EXPR
5301 anymore, or NULL_TREE if no folding opportunity is found. */
5303 static tree
5306 {
5311 tree tem;
5316 /* If we have A op 0 ? A : -A, consider applying the following
5317 transformations:
5319 A == 0? A : -A same as -A
5320 A != 0? A : -A same as A
5321 A >= 0? A : -A same as abs (A)
5322 A > 0? A : -A same as abs (A)
5323 A <= 0? A : -A same as -abs (A)
5324 A < 0? A : -A same as -abs (A)
5326 None of these transformations work for modes with signed
5327 zeros. If A is +/-0, the first two transformations will
5328 change the sign of the result (from +0 to -0, or vice
5329 versa). The last four will fix the sign of the result,
5330 even though the original expressions could be positive or
5331 negative, depending on the sign of A.
5333 Note that all these transformations are correct if A is
5334 NaN, since the two alternatives (A and -A) are also NaNs. */
5341 /* In the case that A is of the form X-Y, '-A' (arg2) may
5342 have already been folded to Y-X, check for that. */
5350 {
5364 /* Fall through. */
5386 }
5388 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5389 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5390 both transformations are correct when A is NaN: A != 0
5391 is then true, and A == 0 is false. */
5395 {
5400 }
5402 /* Try some transformations of A op B ? A : B.
5404 A == B? A : B same as B
5405 A != B? A : B same as A
5406 A >= B? A : B same as max (A, B)
5407 A > B? A : B same as max (B, A)
5408 A <= B? A : B same as min (A, B)
5409 A < B? A : B same as min (B, A)
5411 As above, these transformations don't work in the presence
5412 of signed zeros. For example, if A and B are zeros of
5413 opposite sign, the first two transformations will change
5414 the sign of the result. In the last four, the original
5415 expressions give different results for (A=+0, B=-0) and
5416 (A=-0, B=+0), but the transformed expressions do not.
5418 The first two transformations are correct if either A or B
5419 is a NaN. In the first transformation, the condition will
5420 be false, and B will indeed be chosen. In the case of the
5421 second transformation, the condition A != B will be true,
5422 and A will be chosen.
5424 The conversions to max() and min() are not correct if B is
5425 a number and A is not. The conditions in the original
5426 expressions will be false, so all four give B. The min()
5427 and max() versions would give a NaN instead. */
5430 /* Avoid these transformations if the COND_EXPR may be used
5431 as an lvalue in the C++ front-end. PR c++/19199. */
5432 && (in_gimple_form
5437 {
5442 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5444 {
5448 }
5451 {
5460 /* In C++ a ?: expression can be an lvalue, so put the
5461 operand which will be used if they are equal first
5462 so that we can convert this back to the
5463 corresponding COND_EXPR. */
5465 {
5474 }
5481 {
5490 }
5505 }
5506 }
5508 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5509 we might still be able to simplify this. For example,
5510 if C1 is one less or one more than C2, this might have started
5511 out as a MIN or MAX and been transformed by this function.
5512 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5518 {
5522 /* We can replace A with C1 in this case. */
5527 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5528 MIN_EXPR, to preserve the signedness of the comparison. */
5530 OEP_ONLY_CONST)
5534 OEP_ONLY_CONST))
5535 {
5538 arg2));
5541 }
5545 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5546 as above. */
5548 OEP_ONLY_CONST)
5552 OEP_ONLY_CONST))
5553 {
5556 arg2));
5559 }
5563 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5564 MAX_EXPR, to preserve the signedness of the comparison. */
5566 OEP_ONLY_CONST)
5570 OEP_ONLY_CONST))
5571 {
5574 arg2));
5576 }
5580 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5582 OEP_ONLY_CONST)
5586 OEP_ONLY_CONST))
5587 {
5590 arg2));
5592 }
5598 }
5601 }
5604 \f
5605 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5606 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5607 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5608 false) >= 2)
5609 #endif
5611 /* EXP is some logical combination of boolean tests. See if we can
5612 merge it into some range test. Return the new tree if so. */
5614 static tree
5617 {
5625 tree tem;
5629 /* If this is an OR operation, invert both sides; we will invert
5630 again at the end. */
5634 /* If both expressions are the same, if we can merge the ranges, and we
5635 can build the range test, return it or it inverted. If one of the
5636 ranges is always true or always false, consider it to be the same
5637 expression as the other. */
5645 {
5649 }
5651 /* On machines where the branch cost is expensive, if this is a
5652 short-circuited branch and the underlying object on both sides
5653 is the same, make a non-short-circuit operation. */
5659 {
5660 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5661 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5662 which cases we can't do this. */
5664 {
5670 }
5674 {
5683 {
5686 WARN_STRICT_OVERFLOW_COMPARISON);
5692 }
5693 }
5694 }
5697 }
5698 \f
5699 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5700 bit value. Arrange things so the extra bits will be set to zero if and
5701 only if C is signed-extended to its full width. If MASK is nonzero,
5702 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5704 static tree
5706 {
5709 tree temp;
5714 /* We work by getting just the sign bit into the low-order bit, then
5715 into the high-order bit, then sign-extend. We then XOR that value
5716 with C. */
5720 /* We must use a signed type in order to get an arithmetic right shift.
5721 However, we must also avoid introducing accidental overflows, so that
5722 a subsequent call to integer_zerop will work. Hence we must
5723 do the type conversion here. At this point, the constant is either
5724 zero or one, and the conversion to a signed type can never overflow.
5725 We could get an overflow if this conversion is done anywhere else. */
5735 /* If necessary, convert the type back to match the type of C. */
5741 }
5742 \f
5743 /* Find ways of folding logical expressions of LHS and RHS:
5744 Try to merge two comparisons to the same innermost item.
5745 Look for range tests like "ch >= '0' && ch <= '9'".
5746 Look for combinations of simple terms on machines with expensive branches
5747 and evaluate the RHS unconditionally.
5749 For example, if we have p->a == 2 && p->b == 4 and we can make an
5750 object large enough to span both A and B, we can do this with a comparison
5751 against the object ANDed with the a mask.
5753 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5754 operations to do this with one comparison.
5756 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5757 function and the one above.
5759 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5760 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5762 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5763 two operands.
5765 We return the simplified tree or 0 if no optimization is possible. */
5767 static tree
5770 {
5771 /* If this is the "or" of two comparisons, we can do something if
5772 the comparisons are NE_EXPR. If this is the "and", we can do something
5773 if the comparisons are EQ_EXPR. I.e.,
5774 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5776 WANTED_CODE is this operation code. For single bit fields, we can
5777 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5778 comparison for one-bit fields. */
5800 /* Start by getting the comparison codes. Fail if anything is volatile.
5801 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5802 it were surrounded with a NE_EXPR. */
5811 {
5815 }
5818 {
5822 }
5833 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5836 {
5837 tree result;
5840 {
5845 }
5848 {
5854 }
5855 }
5860 /* If the RHS can be evaluated unconditionally and its operands are
5861 simple, it wins to evaluate the RHS unconditionally on machines
5862 with expensive branches. In this case, this isn't a comparison
5863 that can be merged. Avoid doing this if the RHS is a floating-point
5864 comparison since those can trap. */
5871 {
5872 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5878 {
5884 }
5886 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5892 {
5898 }
5901 {
5903 {
5906 }
5908 }
5909 }
5911 /* See if the comparisons can be merged. Then get all the parameters for
5912 each side. */
5936 /* It must be true that the inner operation on the lhs of each
5937 comparison must be the same if we are to be able to do anything.
5938 Then see if we have constants. If not, the same must be true for
5939 the rhs's. */
5950 else
5953 /* If either comparison code is not correct for our logical operation,
5954 fail. However, we can convert a one-bit comparison against zero into
5955 the opposite comparison against that bit being set in the field. */
5959 {
5961 {
5962 /* Make the left operand unsigned, since we are only interested
5963 in the value of one bit. Otherwise we are doing the wrong
5964 thing below. */
5967 }
5968 else
5970 }
5972 /* This is analogous to the code for l_const above. */
5974 {
5976 {
5979 }
5980 else
5982 }
5984 /* See if we can find a mode that contains both fields being compared on
5985 the left. If we can't, fail. Otherwise, update all constants and masks
5986 to be relative to a field of that size. */
5991 volatilep);
6001 {
6004 }
6012 {
6020 {
6024 }
6025 }
6027 {
6035 {
6039 }
6040 }
6042 /* If the right sides are not constant, do the same for it. Also,
6043 disallow this optimization if a size or signedness mismatch occurs
6044 between the left and right sides. */
6046 {
6049 /* Make sure the two fields on the right
6050 correspond to the left without being swapped. */
6058 volatilep);
6068 {
6071 }
6080 /* Make a mask that corresponds to both fields being compared.
6081 Do this for both items being compared. If the operands are the
6082 same size and the bits being compared are in the same position
6083 then we can do this by masking both and comparing the masked
6084 results. */
6088 {
6101 }
6103 /* There is still another way we can do something: If both pairs of
6104 fields being compared are adjacent, we may be able to make a wider
6105 field containing them both.
6107 Note that we still must mask the lhs/rhs expressions. Furthermore,
6108 the mask must be shifted to account for the shift done by
6109 make_bit_field_ref. */
6114 {
6115 tree type;
6129 /* Convert to the smaller type before masking out unwanted bits. */
6132 {
6134 {
6138 }
6140 {
6144 }
6145 }
6155 }
6158 }
6160 /* Handle the case of comparisons with constants. If there is something in
6161 common between the masks, those bits of the constants must be the same.
6162 If not, the condition is always false. Test for this to avoid generating
6163 incorrect code below. */
6168 {
6170 {
6173 }
6174 else
6175 {
6178 }
6179 }
6181 /* Construct the expression we will return. First get the component
6182 reference we will make. Unless the mask is all ones the width of
6183 that field, perform the mask operation. Then compare with the
6184 merged constant. */
6190 {
6193 }
6198 fold_truthop_exit:
6201 }
6202 \f
6203 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
6204 constant. */
6206 static tree
6209 {
6212 tree comp_const;
6213 tree minmax_const;
6215 tree inner;
6226 /* If something does not permit us to optimize, return the original tree. */
6234 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6235 and GT_EXPR, doing the rest with recursive calls using logical
6236 simplifications. */
6238 {
6240 {
6241 tree tem
6248 }
6251 return
6253 optimize_minmax_comparison
6255 optimize_minmax_comparison
6260 /* MAX (X, 0) == 0 -> X <= 0 */
6264 /* MAX (X, 0) == 5 -> X == 5 */
6268 /* MAX (X, 0) == -1 -> false */
6272 /* MIN (X, 0) == 0 -> X >= 0 */
6276 /* MIN (X, 0) == 5 -> false */
6279 else
6280 /* MIN (X, 0) == -1 -> X == -1 */
6285 /* MAX (X, 0) > 0 -> X > 0
6286 MAX (X, 0) > 5 -> X > 5 */
6290 /* MAX (X, 0) > -1 -> true */
6294 /* MIN (X, 0) > 0 -> false
6295 MIN (X, 0) > 5 -> false */
6298 else
6299 /* MIN (X, 0) > -1 -> X > -1 */
6304 }
6305 }
6306 \f
6307 /* T is an integer expression that is being multiplied, divided, or taken a
6308 modulus (CODE says which and what kind of divide or modulus) by a
6309 constant C. See if we can eliminate that operation by folding it with
6310 other operations already in T. WIDE_TYPE, if non-null, is a type that
6311 should be used for the computation if wider than our type.
6313 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6314 (X * 2) + (Y * 4). We must, however, be assured that either the original
6315 expression would not overflow or that overflow is undefined for the type
6316 in the language in question.
6318 If we return a non-null expression, it is an equivalent form of the
6319 original computation, but need not be in the original type.
6321 We set *STRICT_OVERFLOW_P to true if the return values depends on
6322 signed overflow being undefined. Otherwise we do not change
6323 *STRICT_OVERFLOW_P. */
6325 static tree
6328 {
6329 /* To avoid exponential search depth, refuse to allow recursion past
6330 three levels. Beyond that (1) it's highly unlikely that we'll find
6331 something interesting and (2) we've probably processed it before
6332 when we built the inner expression. */
6335 tree ret;
6340 depth++;
6342 depth--;
6345 }
6347 static tree
6350 {
6361 /* Don't deal with constants of zero here; they confuse the code below. */
6371 /* Note that we need not handle conditional operations here since fold
6372 already handles those cases. So just do arithmetic here. */
6374 {
6376 /* For a constant, we can always simplify if we are a multiply
6377 or (for divide and modulus) if it is a multiple of our constant. */
6385 /* If op0 is an expression ... */
6391 /* ... and has wrapping overflow, and its type is smaller
6392 than ctype, then we cannot pass through as widening. */
6398 /* ... or this is a truncation (t is narrower than op0),
6399 then we cannot pass through this narrowing. */
6402 /* ... or signedness changes for division or modulus,
6403 then we cannot pass through this conversion. */
6407 /* ... or has undefined overflow while the converted to
6408 type has not, we cannot do the operation in the inner type
6409 as that would introduce undefined overflow. */
6414 /* Pass the constant down and see if we can make a simplification. If
6415 we can, replace this expression with the inner simplification for
6416 possible later conversion to our or some other type. */
6421 code == MULT_EXPR
6423 strict_overflow_p))))
6428 /* If widening the type changes it from signed to unsigned, then we
6429 must avoid building ABS_EXPR itself as unsigned. */
6431 {
6435 {
6438 }
6440 }
6441 /* If the constant is negative, we cannot simplify this. */
6444 /* FALLTHROUGH */
6452 /* If widening the type changes the signedness, then we can't perform
6453 this optimization as that changes the result. */
6457 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6463 {
6470 }
6474 /* If the second operand is constant, this is a multiplication
6475 or floor division, by a power of two, so we can treat it that
6476 way unless the multiplier or divisor overflows. Signed
6477 left-shift overflow is implementation-defined rather than
6478 undefined in C90, so do not convert signed left shift into
6479 multiplication. */
6482 /* const_binop may not detect overflow correctly,
6483 so check for it explicitly here. */
6488 size_one_node,
6493 ctype,
6495 t1),
6500 /* See if we can eliminate the operation on both sides. If we can, we
6501 can return a new PLUS or MINUS. If we can't, the only remaining
6502 cases where we can do anything are if the second operand is a
6503 constant. */
6509 /* If not multiplication, we can only do this if both operands
6510 are divisible by c. */
6513 {
6518 }
6520 /* If this was a subtraction, negate OP1 and set it to be an addition.
6521 This simplifies the logic below. */
6523 {
6525 /* If OP1 was not easily negatable, the constant may be OP0. */
6527 {
6534 }
6535 }
6540 /* If either OP1 or C are negative, this optimization is not safe for
6541 some of the division and remainder types while for others we need
6542 to change the code. */
6544 {
6552 }
6554 /* If it's a multiply or a division/modulus operation of a multiple
6555 of our constant, do the operation and verify it doesn't overflow. */
6558 {
6561 /* We allow the constant to overflow with wrapping semantics. */
6565 }
6566 else
6569 /* If we have an unsigned type is not a sizetype, we cannot widen
6570 the operation since it will change the result if the original
6571 computation overflowed. */
6577 /* If we were able to eliminate our operation from the first side,
6578 apply our operation to the second side and reform the PLUS. */
6582 /* The last case is if we are a multiply. In that case, we can
6583 apply the distributive law to commute the multiply and addition
6584 if the multiplication of the constants doesn't overflow. */
6590 op1);
6595 /* We have a special case here if we are doing something like
6596 (C * 8) % 4 since we know that's zero. */
6599 /* If the multiplication can overflow we cannot optimize this.
6600 ??? Until we can properly mark individual operations as
6601 not overflowing we need to treat sizetype special here as
6602 stor-layout relies on this opimization to make
6603 DECL_FIELD_BIT_OFFSET always a constant. */
6609 {
6612 }
6614 /* ... fall through ... */
6618 /* If we can extract our operation from the LHS, do so and return a
6619 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6620 do something only if the second operand is a constant. */
6634 /* If these are the same operation types, we can associate them
6635 assuming no overflow. */
6648 /* If these operations "cancel" each other, we have the main
6649 optimizations of this pass, which occur when either constant is a
6650 multiple of the other, in which case we replace this with either an
6651 operation or CODE or TCODE.
6653 If we have an unsigned type that is not a sizetype, we cannot do
6654 this since it will change the result if the original computation
6655 overflowed. */
6663 {
6665 {
6672 }
6674 {
6681 }
6682 }
6687 }
6690 }
6691 \f
6692 /* Return a node which has the indicated constant VALUE (either 0 or
6693 1), and is of the indicated TYPE. */
6695 tree
6697 {
6702 else
6704 }
6707 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6708 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6709 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6710 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6711 COND is the first argument to CODE; otherwise (as in the example
6712 given here), it is the second argument. TYPE is the type of the
6713 original expression. Return NULL_TREE if no simplification is
6714 possible. */
6716 static tree
6721 {
6728 /* This transformation is only worthwhile if we don't have to wrap
6729 arg in a SAVE_EXPR, and the operation can be simplified on at least
6730 one of the branches once its pushed inside the COND_EXPR. */
6735 {
6739 /* If this operand throws an expression, then it does not make
6740 sense to try to perform a logical or arithmetic operation
6741 involving it. */
6746 }
6747 else
6748 {
6753 }
6757 {
6761 else
6763 }
6765 {
6769 else
6771 }
6775 }
6777 \f
6778 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6780 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6781 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6782 ADDEND is the same as X.
6784 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6785 and finite. The problematic cases are when X is zero, and its mode
6786 has signed zeros. In the case of rounding towards -infinity,
6787 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6788 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6790 bool
6792 {
6796 /* Don't allow the fold with -fsignaling-nans. */
6800 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6804 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6809 /* The mode has signed zeros, and we have to honor their sign.
6810 In this situation, there is only one case we can return true for.
6811 X - 0 is the same as X unless rounding towards -infinity is
6812 supported. */
6814 }
6816 /* Subroutine of fold() that checks comparisons of built-in math
6817 functions against real constants.
6819 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6820 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6821 is the type of the result and ARG0 and ARG1 are the operands of the
6822 comparison. ARG1 must be a TREE_REAL_CST.
6824 The function returns the constant folded tree if a simplification
6825 can be made, and NULL_TREE otherwise. */
6827 static tree
6831 {
6832 REAL_VALUE_TYPE c;
6835 {
6841 {
6842 /* sqrt(x) < y is always false, if y is negative. */
6846 /* sqrt(x) > y is always true, if y is negative and we
6847 don't care about NaNs, i.e. negative values of x. */
6851 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6854 }
6856 {
6857 REAL_VALUE_TYPE c2;
6863 {
6864 /* sqrt(x) > y is x == +Inf, when y is very large. */
6869 /* sqrt(x) > y is always false, when y is very large
6870 and we don't care about infinities. */
6872 }
6874 /* sqrt(x) > c is the same as x > c*c. */
6877 }
6879 {
6880 REAL_VALUE_TYPE c2;
6886 {
6887 /* sqrt(x) < y is always true, when y is a very large
6888 value and we don't care about NaNs or Infinities. */
6892 /* sqrt(x) < y is x != +Inf when y is very large and we
6893 don't care about NaNs. */
6898 /* sqrt(x) < y is x >= 0 when y is very large and we
6899 don't care about Infinities. */
6904 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6913 dconst0)),
6916 c2)));
6917 }
6919 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6924 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6927 {
6932 dconst0)),
6935 c2)));
6936 }
6937 }
6938 }
6941 }
6943 /* Subroutine of fold() that optimizes comparisons against Infinities,
6944 either +Inf or -Inf.
6946 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6947 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6948 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6950 The function returns the constant folded tree if a simplification
6951 can be made, and NULL_TREE otherwise. */
6953 static tree
6956 {
6958 REAL_VALUE_TYPE max;
6959 tree temp;
6964 /* For negative infinity swap the sense of the comparison. */
6970 {
6972 /* x > +Inf is always false, if with ignore sNANs. */
6978 /* x <= +Inf is always true, if we don't case about NaNs. */
6982 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6985 {
6988 }
6993 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6999 /* x < +Inf is always equal to x <= DBL_MAX. */
7005 /* x != +Inf is always equal to !(x > DBL_MAX). */
7017 }
7020 }
7022 /* Subroutine of fold() that optimizes comparisons of a division by
7023 a nonzero integer constant against an integer constant, i.e.
7024 X/C1 op C2.
7026 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7027 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
7028 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
7030 The function returns the constant folded tree if a simplification
7031 can be made, and NULL_TREE otherwise. */
7033 static tree
7036 {
7041 HOST_WIDE_INT hpart;
7046 /* We have to do this the hard way to detect unsigned overflow.
7047 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
7058 {
7063 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
7071 }
7073 {
7077 {
7096 }
7097 }
7098 else
7099 {
7100 /* A negative divisor reverses the relational operators. */
7106 {
7125 }
7126 }
7129 {
7150 {
7153 }
7158 {
7161 }
7166 {
7169 }
7174 {
7177 }
7182 }
7185 }
7188 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7189 equality/inequality test, then return a simplified form of the test
7190 using a sign testing. Otherwise return NULL. TYPE is the desired
7191 result type. */
7193 static tree
7196 tree result_type)
7197 {
7198 /* If this is testing a single bit, we can optimize the test. */
7202 {
7203 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7204 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7208 /* This is only a win if casting to a signed type is cheap,
7209 i.e. when arg00's type is not a partial mode. */
7212 {
7215 result_type,
7218 }
7219 }
7222 }
7224 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7225 equality/inequality test, then return a simplified form of
7226 the test using shifts and logical operations. Otherwise return
7227 NULL. TYPE is the desired result type. */
7229 tree
7232 {
7233 /* If this is testing a single bit, we can optimize the test. */
7237 {
7246 /* First, see if we can fold the single bit test into a sign-bit
7247 test. */
7249 result_type);
7253 /* Otherwise we have (A & C) != 0 where C is a single bit,
7254 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7255 Similarly for (A & C) == 0. */
7257 /* If INNER is a right shift of a constant and it plus BITNUM does
7258 not overflow, adjust BITNUM and INNER. */
7265 {
7268 }
7270 /* If we are going to be able to omit the AND below, we must do our
7271 operations as unsigned. If we must use the AND, we have a choice.
7272 Normally unsigned is faster, but for some machines signed is. */
7273 #ifdef LOAD_EXTEND_OP
7276 #else
7278 #endif
7294 /* Put the AND last so it can combine with more things. */
7297 /* Make sure to return the proper type. */
7301 }
7303 }
7305 /* Check whether we are allowed to reorder operands arg0 and arg1,
7306 such that the evaluation of arg1 occurs before arg0. */
7308 static bool
7310 {
7317 }
7319 /* Test whether it is preferable two swap two operands, ARG0 and
7320 ARG1, for example because ARG0 is an integer constant and ARG1
7321 isn't. If REORDER is true, only recommend swapping if we can
7322 evaluate the operands in reverse order. */
7324 bool
7326 {
7362 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7363 for commutative and comparison operators. Ensuring a canonical
7364 form allows the optimizers to find additional redundancies without
7365 having to explicitly check for both orderings. */
7371 /* Put SSA_NAMEs last. */
7377 /* Put variables last. */
7384 }
7386 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7387 ARG0 is extended to a wider type. */
7389 static tree
7392 {
7394 tree arg1_unw;
7403 #ifdef HAVE_canonicalize_funcptr_for_compare
7404 /* Disable this optimization if we're casting a function pointer
7405 type on targets that require function pointer canonicalization. */
7410 #endif
7417 /* If possible, express the comparison in the shorter mode. */
7437 /* If we are comparing with the integer that does not fit into the range
7438 of the shorter type, the result is known. */
7449 {
7476 }
7479 }
7481 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7482 ARG0 just the signedness is changed. */
7484 static tree
7487 {
7488 tree arg0_inner;
7498 #ifdef HAVE_canonicalize_funcptr_for_compare
7499 /* Disable this optimization if we're casting a function pointer
7500 type on targets that require function pointer canonicalization. */
7505 #endif
7525 else
7529 }
7531 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7532 step of the array. Reconstructs s and delta in the case of s *
7533 delta being an integer constant (and thus already folded). ADDR is
7534 the address. MULT is the multiplicative expression. If the
7535 function succeeds, the new address expression is returned.
7536 Otherwise NULL_TREE is returned. LOC is the location of the
7537 resulting expression. */
7539 static tree
7541 {
7545 tree itype;
7548 /* Strip the nops that might be added when converting op1 to sizetype. */
7551 /* Canonicalize op1 into a possibly non-constant delta
7552 and an INTEGER_CST s. */
7554 {
7561 {
7564 }
7566 {
7569 }
7570 else
7572 }
7574 {
7577 }
7578 else
7579 {
7580 /* Simulate we are delta * 1. */
7583 }
7586 {
7588 {
7589 /* Remember if this was a multi-dimensional array. */
7602 {
7605 }
7606 else
7607 {
7608 /* Try if delta is a multiple of step. */
7613 }
7615 /* Only fold here if we can verify we do not overflow one
7616 dimension of a multi-dimensional array. */
7618 {
7619 tree tmp;
7635 }
7638 }
7639 else
7644 }
7646 /* We found the suitable array reference. So copy everything up to it,
7647 and replace the index. */
7655 {
7659 }
7667 }
7670 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7671 means A >= Y && A != MAX, but in this case we know that
7672 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7674 static tree
7676 {
7683 else
7692 {
7695 }
7697 {
7700 }
7701 else
7708 {
7709 /* Convert the pointer types into integer before taking the difference. */
7713 }
7714 else
7721 }
7723 /* Fold a sum or difference of at least one multiplication.
7724 Returns the folded tree or NULL if no simplification could be made. */
7726 static tree
7729 {
7733 /* (A * C) +- (B * C) -> (A+-B) * C.
7734 (A * C) +- A -> A * (C+-1).
7735 We are most concerned about the case where C is a constant,
7736 but other combinations show up during loop reduction. Since
7737 it is not difficult, try all four possibilities. */
7740 {
7743 }
7745 {
7748 }
7749 else
7750 {
7751 /* We cannot generate constant 1 for fract. */
7756 }
7758 {
7761 }
7763 {
7765 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7766 the purpose of this canonicalization. */
7770 {
7773 }
7774 else
7776 }
7777 else
7778 {
7779 /* We cannot generate constant 1 for fract. */
7784 }
7796 /* No identical multiplicands; see if we can find a common
7797 power-of-two factor in non-power-of-two multiplies. This
7798 can help in multi-dimensional array access. */
7801 {
7804 tree maybe_same;
7808 /* Move min of absolute values to int11. */
7811 {
7816 }
7817 else
7821 /* The remainder should not be a constant, otherwise we
7822 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7823 increased the number of multiplications necessary. */
7825 {
7833 }
7834 }
7844 }
7846 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7847 specified by EXPR into the buffer PTR of length LEN bytes.
7848 Return the number of bytes placed in the buffer, or zero
7849 upon failure. */
7851 static int
7853 {
7864 {
7868 else
7873 {
7880 else
7882 }
7883 else
7886 }
7888 }
7891 /* Subroutine of native_encode_expr. Encode the REAL_CST
7892 specified by EXPR into the buffer PTR of length LEN bytes.
7893 Return the number of bytes placed in the buffer, or zero
7894 upon failure. */
7896 static int
7898 {
7904 /* There are always 32 bits in each long, no matter the size of
7905 the hosts long. We handle floating point representations with
7906 up to 192 bits. */
7917 {
7922 {
7929 else
7931 }
7932 else
7935 }
7937 }
7939 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7940 specified by EXPR into the buffer PTR of length LEN bytes.
7941 Return the number of bytes placed in the buffer, or zero
7942 upon failure. */
7944 static int
7946 {
7948 tree part;
7959 }
7962 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7963 specified by EXPR into the buffer PTR of length LEN bytes.
7964 Return the number of bytes placed in the buffer, or zero
7965 upon failure. */
7967 static int
7969 {
7979 {
7981 {
7984 }
7985 else
7989 {
7992 }
7993 else
7994 {
7998 }
8000 }
8002 }
8005 /* Subroutine of native_encode_expr. Encode the STRING_CST
8006 specified by EXPR into the buffer PTR of length LEN bytes.
8007 Return the number of bytes placed in the buffer, or zero
8008 upon failure. */
8010 static int
8012 {
8014 HOST_WIDE_INT total_bytes;
8025 {
8029 }
8030 else
8033 }
8036 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
8037 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
8038 buffer PTR of length LEN bytes. Return the number of bytes
8039 placed in the buffer, or zero upon failure. */
8041 int
8043 {
8045 {
8063 }
8064 }
8067 /* Subroutine of native_interpret_expr. Interpret the contents of
8068 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8069 If the buffer cannot be interpreted, return NULL_TREE. */
8071 static tree
8073 {
8087 {
8090 {
8097 else
8099 }
8100 else
8106 else
8109 }
8112 }
8115 /* Subroutine of native_interpret_expr. Interpret the contents of
8116 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8117 If the buffer cannot be interpreted, return NULL_TREE. */
8119 static tree
8121 {
8126 /* There are always 32 bits in each long, no matter the size of
8127 the hosts long. We handle floating point representations with
8128 up to 192 bits. */
8129 REAL_VALUE_TYPE r;
8140 {
8143 {
8150 else
8152 }
8153 else
8158 }
8162 }
8165 /* Subroutine of native_interpret_expr. Interpret the contents of
8166 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8167 If the buffer cannot be interpreted, return NULL_TREE. */
8169 static tree
8171 {
8186 }
8189 /* Subroutine of native_interpret_expr. Interpret the contents of
8190 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8191 If the buffer cannot be interpreted, return NULL_TREE. */
8193 static tree
8195 {
8207 {
8212 }
8214 }
8217 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8218 the buffer PTR of length LEN as a constant of type TYPE. For
8219 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8220 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8221 return NULL_TREE. */
8223 tree
8225 {
8227 {
8244 }
8245 }
8248 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
8249 TYPE at compile-time. If we're unable to perform the conversion
8250 return NULL_TREE. */
8252 static tree
8254 {
8255 /* We support up to 512-bit values (for V8DFmode). */
8259 /* Check that the host and target are sane. */
8268 }
8270 /* Build an expression for the address of T. Folds away INDIRECT_REF
8271 to avoid confusing the gimplify process. */
8273 tree
8275 {
8276 /* The size of the object is not relevant when talking about its address. */
8280 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8283 {
8287 {
8290 }
8291 }
8293 {
8298 }
8299 else
8300 {
8303 }
8306 }
8308 /* Build an expression for the address of T. */
8310 tree
8312 {
8316 }
8318 /* Fold a unary expression of code CODE and type TYPE with operand
8319 OP0. Return the folded expression if folding is successful.
8320 Otherwise, return NULL_TREE. */
8322 tree
8324 {
8325 tree tem;
8326 tree arg0;
8334 {
8337 {
8338 /* Don't use STRIP_NOPS, because signedness of argument type
8339 matters. */
8341 }
8342 else
8343 {
8344 /* Strip any conversions that don't change the mode. This
8345 is safe for every expression, except for a comparison
8346 expression because its signedness is derived from its
8347 operands.
8349 Note that this is done as an internal manipulation within
8350 the constant folder, in order to find the simplest
8351 representation of the arguments so that their form can be
8352 studied. In any cases, the appropriate type conversions
8353 should be put back in the tree that will get out of the
8354 constant folder. */
8356 }
8357 }
8360 {
8367 {
8381 /* If this was a conversion, and all we did was to move into
8382 inside the COND_EXPR, bring it back out. But leave it if
8383 it is a conversion from integer to integer and the
8384 result precision is no wider than a word since such a
8385 conversion is cheap and may be optimized away by combine,
8386 while it couldn't if it were outside the COND_EXPR. Then return
8387 so we don't get into an infinite recursion loop taking the
8388 conversion out and then back in. */
8400 && (INTEGRAL_TYPE_P
8404 {
8413 }
8415 }
8417 {
8419 {
8423 }
8427 integer_one_node),
8429 integer_zero_node));
8430 }
8431 }
8434 {
8436 /* Re-association barriers around constants and other re-association
8437 barriers can be removed. */
8443 CASE_CONVERT:
8449 /* If we have (type) (a CMP b) and type is an integral type, return
8450 new expression involving the new type. */
8455 /* Handle cases of two conversions in a row. */
8457 {
8479 /* In addition to the cases of two conversions in a row
8480 handled below, if we are converting something to its own
8481 type via an object of identical or wider precision, neither
8482 conversion is needed. */
8489 /* Likewise, if the intermediate and initial types are either both
8490 float or both integer, we don't need the middle conversion if the
8491 former is wider than the latter and doesn't change the signedness
8492 (for integers). Avoid this if the final type is a pointer since
8493 then we sometimes need the middle conversion. Likewise if the
8494 final type has a precision not equal to the size of its mode. */
8503 && ! final_ptr
8507 /* If we have a sign-extension of a zero-extended value, we can
8508 replace that by a single zero-extension. */
8514 /* Two conversions in a row are not needed unless:
8515 - some conversion is floating-point (overstrict for now), or
8516 - some conversion is a vector (overstrict for now), or
8517 - the intermediate type is narrower than both initial and
8518 final, or
8519 - the intermediate type and innermost type differ in signedness,
8520 and the outermost type is wider than the intermediate, or
8521 - the initial type is a pointer type and the precisions of the
8522 intermediate and final types differ, or
8523 - the final type is a pointer type and the precisions of the
8524 initial and intermediate types differ. */
8538 }
8540 /* Handle (T *)&A.B.C for A being of type T and B and C
8541 living at offset zero. This occurs frequently in
8542 C++ upcasting and then accessing the base. */
8546 {
8548 tree offset;
8554 /* If the reference was to a (constant) zero offset, we can use
8555 the address of the base if it has the same base type
8556 as the result type. */
8562 }
8566 /* Detect assigning a bitfield. */
8568 && DECL_BIT_FIELD
8570 {
8571 /* Don't leave an assignment inside a conversion
8572 unless assigning a bitfield. */
8574 /* First do the assignment, then return converted constant. */
8580 }
8582 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8583 constants (if x has signed type, the sign bit cannot be set
8584 in c). This folds extension into the BIT_AND_EXPR.
8585 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8586 very likely don't have maximal range for their precision and this
8587 transformation effectively doesn't preserve non-maximal ranges. */
8591 {
8602 <= HOST_BITS_PER_WIDE_INT
8604 {
8611 #ifdef LOAD_EXTEND_OP
8613 && !flag_syntax_only
8616 {
8620 }
8621 #endif
8622 }
8624 {
8630 }
8631 }
8633 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8634 when one of the new casts will fold away. Conservatively we assume
8635 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8641 {
8649 }
8651 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8652 of the same precision, and X is an integer type not narrower than
8653 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8659 {
8665 }
8667 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8668 type of X and Y (integer types only). */
8673 {
8674 /* Be careful not to introduce new overflows. */
8675 tree mult_type;
8678 else
8682 {
8689 }
8690 }
8711 /* For integral conversions with the same precision or pointer
8712 conversions use a NOP_EXPR instead. */
8720 /* Strip inner integral conversions that do not change the precision. */
8744 /* Convert fabs((double)float) into (double)fabsf(float). */
8747 {
8753 targ0));
8754 }
8755 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8761 /* Strip sign ops from argument. */
8763 {
8768 }
8775 {
8781 }
8783 {
8788 }
8798 /* Convert ~ (-A) to A - 1. */
8803 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8812 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8827 /* Perform BIT_NOT_EXPR on each element individually. */
8829 {
8834 {
8836 {
8842 }
8843 else
8846 }
8849 }
8854 /* The argument to invert_truthvalue must have Boolean type. */
8858 /* Note that the operand of this must be an int
8859 and its values must be 0 or 1.
8860 ("true" is a fixed value perhaps depending on the language,
8861 but we don't handle values other than 1 correctly yet.) */
8876 {
8884 }
8886 {
8891 }
8893 {
8897 {
8906 }
8907 }
8919 {
8927 }
8929 {
8933 }
8935 {
8939 {
8948 }
8949 }
8955 }
8958 /* If the operation was a conversion do _not_ mark a resulting constant
8959 with TREE_OVERFLOW if the original constant was not. These conversions
8960 have implementation defined behavior and retaining the TREE_OVERFLOW
8961 flag here would confuse later passes such as VRP. */
8962 tree
8965 {
8974 }
8976 /* Fold a binary expression of code CODE and type TYPE with operands
8977 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8978 Return the folded expression if folding is successful. Otherwise,
8979 return NULL_TREE. */
8981 static tree
8983 {
8990 else
8993 /* MIN (MAX (a, b), b) == b. */
8998 /* MIN (MAX (b, a), b) == b. */
9004 /* MIN (a, MAX (a, b)) == a. */
9010 /* MIN (a, MAX (b, a)) == a. */
9017 }
9019 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9020 by changing CODE to reduce the magnitude of constants involved in
9021 ARG0 of the comparison.
9022 Returns a canonicalized comparison tree if a simplification was
9023 possible, otherwise returns NULL_TREE.
9024 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9025 valid if signed overflow is undefined. */
9027 static tree
9031 {
9037 /* Match A +- CST code arg1 and CST code arg1. We can change the
9038 first form only if overflow is undefined. */
9040 /* In principle pointers also have undefined overflow behavior,
9041 but that causes problems elsewhere. */
9049 /* Identify the constant in arg0 and its sign. */
9052 else
9056 /* Overflowed constants and zero will cause problems. */
9061 /* See if we can reduce the magnitude of the constant in
9062 arg0 by changing the comparison code. */
9064 {
9065 /* CST <= arg1 -> CST-1 < arg1. */
9068 /* -CST < arg1 -> -CST-1 <= arg1. */
9071 /* CST > arg1 -> CST-1 >= arg1. */
9074 /* -CST >= arg1 -> -CST-1 > arg1. */
9077 else
9079 /* arg1 code' CST' might be more canonical. */
9081 }
9082 else
9083 {
9084 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9088 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9092 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9096 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9100 else
9103 }
9105 /* Now build the constant reduced in magnitude. But not if that
9106 would produce one outside of its types range. */
9114 /* We cannot swap the comparison here as that would cause us to
9115 endlessly recurse. */
9123 /* If swapping might yield to a more canonical form, do so. */
9126 else
9128 }
9130 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9131 overflow further. Try to decrease the magnitude of constants involved
9132 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9133 and put sole constants at the second argument position.
9134 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9136 static tree
9139 {
9140 tree t;
9145 /* Try canonicalization by simplifying arg0. */
9150 {
9154 }
9156 /* Try canonicalization by simplifying arg1 using the swapped
9157 comparison. */
9165 }
9167 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9168 space. This is used to avoid issuing overflow warnings for
9169 expressions like &p->x which can not wrap. */
9171 static bool
9173 {
9184 {
9187 }
9190 else
9191 {
9194 }
9209 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9210 array. */
9212 {
9213 HOST_WIDE_INT base_size;
9218 }
9221 }
9223 /* Subroutine of fold_binary. This routine performs all of the
9224 transformations that are common to the equality/inequality
9225 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9226 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9227 fold_binary should call fold_binary. Fold a comparison with
9228 tree code CODE and type TYPE with operands OP0 and OP1. Return
9229 the folded comparison or NULL_TREE. */
9231 static tree
9234 {
9247 /* If one arg is a real or integer constant, put it last. */
9251 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
9258 {
9262 tree lhs;
9269 /* If the constant operation overflowed this can be
9270 simplified as a comparison against INT_MAX/INT_MIN. */
9273 {
9277 /* Get the sign of the constant on the lhs if the
9278 operation were VARIABLE + CONST1. */
9282 /* The sign of the constant determines if we overflowed
9283 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9284 Canonicalize to the INT_MIN overflow by swapping the comparison
9285 if necessary. */
9289 /* We now can look at the canonicalized case
9290 VARIABLE + 1 CODE2 INT_MIN
9291 and decide on the result. */
9300 }
9305 {
9307 "when changing X +- C1 cmp C2 to "
9309 WARN_STRICT_OVERFLOW_COMPARISON);
9311 }
9312 }
9314 /* For comparisons of pointers we can decompose it to a compile time
9315 comparison of the base objects and the offsets into the object.
9316 This requires at least one operand being an ADDR_EXPR or a
9317 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9323 {
9330 /* Get base and offset for the access. Strip ADDR_EXPR for
9331 get_inner_reference, but put it back by stripping INDIRECT_REF
9332 off the base object if possible. indirect_baseN will be true
9333 if baseN is not an address but refers to the object itself. */
9336 {
9342 else
9344 }
9346 {
9349 }
9353 {
9359 else
9361 }
9363 {
9366 }
9368 /* If we have equivalent bases we might be able to simplify. */
9371 {
9372 /* We can fold this expression to a constant if the non-constant
9373 offset parts are equal. */
9381 {
9388 "occur when comparing P +- C1 with "
9390 WARN_STRICT_OVERFLOW_CONDITIONAL);
9393 {
9407 }
9408 }
9409 /* We can simplify the comparison to a comparison of the variable
9410 offset parts if the constant offset parts are equal.
9411 Be careful to use signed size type here because otherwise we
9412 mess with array offsets in the wrong way. This is possible
9413 because pointer arithmetic is restricted to retain within an
9414 object and overflow on pointer differences is undefined as of
9415 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9419 {
9420 tree signed_size_type_node;
9423 /* By converting to signed size type we cover middle-end pointer
9424 arithmetic which operates on unsigned pointer types of size
9425 type size and ARRAY_REF offsets which are properly sign or
9426 zero extended from their type in case it is narrower than
9427 size type. */
9430 else
9432 offset0);
9435 else
9437 offset1);
9444 "occur when comparing P +- C1 with "
9446 WARN_STRICT_OVERFLOW_COMPARISON);
9449 }
9450 }
9451 /* For non-equal bases we can simplify if they are addresses
9452 of local binding decls or constants. */
9454 /* We know that !operand_equal_p (base0, base1, 0)
9455 because the if condition was false. But make
9456 sure two decls are not the same. */
9470 {
9477 }
9478 /* For equal offsets we can simplify to a comparison of the
9479 base addresses. */
9481 && (indirect_base0
9483 && (indirect_base1
9488 {
9494 }
9495 }
9497 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9498 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9499 the resulting offset is smaller in absolute value than the
9500 original one. */
9508 {
9513 tree cst;
9515 "occur when combining constants around "
9518 /* Put the constant on the side where it doesn't overflow and is
9519 of lower absolute value than before. */
9525 {
9528 variable1,
9532 }
9539 {
9544 variable2);
9545 }
9546 }
9548 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9549 signed arithmetic case. That form is created by the compiler
9550 often enough for folding it to be of value. One example is in
9551 computing loop trip counts after Operator Strength Reduction. */
9557 {
9566 "eliminating multiplication in comparison "
9568 WARN_STRICT_OVERFLOW_COMPARISON);
9570 /* If const1 is negative we swap the sense of the comparison. */
9575 }
9582 {
9590 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9596 /* (-a) CMP (-b) -> b CMP a */
9603 {
9604 REAL_VALUE_TYPE cst;
9607 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9614 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9615 /* a CMP (-0) -> a CMP 0 */
9620 /* x != NaN is always true, other ops are always false. */
9623 {
9626 }
9628 /* Fold comparisons against infinity. */
9631 {
9635 }
9636 }
9638 /* If this is a comparison of a real constant with a PLUS_EXPR
9639 or a MINUS_EXPR of a real constant, we can convert it into a
9640 comparison with a revised real constant as long as no overflow
9641 occurs when unsafe_math_optimizations are enabled. */
9653 /* Likewise, we can simplify a comparison of a real constant with
9654 a MINUS_EXPR whose first operand is also a real constant, i.e.
9655 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9656 floating-point types only if -fassociative-math is set. */
9667 /* Fold comparisons against built-in math functions. */
9669 && flag_unsafe_math_optimizations
9671 {
9675 {
9679 }
9680 }
9681 }
9685 {
9686 /* If we are widening one operand of an integer comparison,
9687 see if the other operand is similarly being widened. Perhaps we
9688 can do the comparison in the narrower type. */
9693 /* Or if we are changing signedness. */
9697 }
9699 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9700 constant, we can simplify it. */
9705 {
9709 }
9711 /* Simplify comparison of something with itself. (For IEEE
9712 floating-point, we can only do some of these simplifications.) */
9714 {
9716 {
9731 /* For NE, we can only do this simplification if integer
9732 or we don't honor IEEE floating point NaNs. */
9736 /* ... fall through ... */
9742 }
9743 }
9745 /* If we are comparing an expression that just has comparisons
9746 of two integer values, arithmetic expressions of those comparisons,
9747 and constants, we can simplify it. There are only three cases
9748 to check: the two values can either be equal, the first can be
9749 greater, or the second can be greater. Fold the expression for
9750 those three values. Since each value must be 0 or 1, we have
9751 eight possibilities, each of which corresponds to the constant 0
9752 or 1 or one of the six possible comparisons.
9754 This handles common cases like (a > b) == 0 but also handles
9755 expressions like ((x > y) - (y > x)) > 0, which supposedly
9756 occur in macroized code. */
9759 {
9764 /* Don't handle degenerate cases here; they should already
9765 have been handled anyway. */
9774 {
9778 /* We can't just pass T to eval_subst in case cval1 or cval2
9779 was the same as ARG1. */
9781 tree high_result
9785 arg1);
9786 tree equal_result
9790 arg1);
9791 tree low_result
9795 arg1);
9797 /* All three of these results should be 0 or 1. Confirm they are.
9798 Then use those values to select the proper code to use. */
9803 {
9804 /* Make a 3-bit mask with the high-order bit being the
9805 value for `>', the next for '=', and the low for '<'. */
9809 {
9811 /* Always false. */
9832 /* Always true. */
9834 }
9837 {
9841 }
9843 }
9844 }
9845 }
9847 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9848 into a single range test. */
9856 {
9860 }
9862 /* Fold ~X op ~Y as Y op X. */
9865 {
9871 }
9873 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9876 {
9882 }
9885 }
9888 /* Subroutine of fold_binary. Optimize complex multiplications of the
9889 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9890 argument EXPR represents the expression "z" of type TYPE. */
9892 static tree
9894 {
9899 {
9902 }
9904 {
9907 }
9908 else
9909 {
9913 }
9922 }
9925 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9926 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9927 guarantees that P and N have the same least significant log2(M) bits.
9928 N is not otherwise constrained. In particular, N is not normalized to
9929 0 <= N < M as is common. In general, the precise value of P is unknown.
9930 M is chosen as large as possible such that constant N can be determined.
9932 Returns M and sets *RESIDUE to N.
9934 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9935 account. This is not always possible due to PR 35705.
9936 */
9938 static unsigned HOST_WIDE_INT
9941 {
9948 {
9951 {
9953 tree offset;
9961 {
9964 else
9965 /* We don't handle more complicated offset expressions. */
9967 }
9968 }
9973 }
9975 {
9983 allow_func_align);
9989 {
9992 }
9994 {
9997 {
10000 /* Compute the greatest power-of-2 divisor of op1. */
10004 /* If align is non-zero and less than *modulus, replace
10005 *modulus with align., If align is 0, then either op1 is 0
10006 or the greatest power-of-2 divisor of op1 doesn't fit in an
10007 unsigned HOST_WIDE_INT. In either case, no additional
10008 constraint is imposed. */
10013 }
10014 }
10015 }
10017 /* If we get here, we were unable to determine anything useful about the
10018 expression. */
10020 }
10023 /* Fold a binary expression of code CODE and type TYPE with operands
10024 OP0 and OP1. LOC is the location of the resulting expression.
10025 Return the folded expression if folding is successful. Otherwise,
10026 return NULL_TREE. */
10028 tree
10031 {
10045 /* Strip any conversions that don't change the mode. This is
10046 safe for every expression, except for a comparison expression
10047 because its signedness is derived from its operands. So, in
10048 the latter case, only strip conversions that don't change the
10049 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10050 preserved.
10052 Note that this is done as an internal manipulation within the
10053 constant folder, in order to find the simplest representation
10054 of the arguments so that their form can be studied. In any
10055 cases, the appropriate type conversions should be put back in
10056 the tree that will get out of the constant folder. */
10059 {
10062 }
10063 else
10064 {
10067 }
10069 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10070 constant but we can't do arithmetic on them. */
10077 {
10079 {
10080 /* Make sure type and arg0 have the same saturating flag. */
10084 }
10087 else
10091 {
10095 }
10096 }
10098 /* If this is a commutative operation, and ARG0 is a constant, move it
10099 to ARG1 to reduce the number of tests below. */
10104 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10106 First check for cases where an arithmetic operation is applied to a
10107 compound, conditional, or comparison operation. Push the arithmetic
10108 operation inside the compound or conditional to see if any folding
10109 can then be done. Convert comparison to conditional for this purpose.
10110 The also optimizes non-constant cases that used to be done in
10111 expand_expr.
10113 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10114 one of the operands is a comparison and the other is a comparison, a
10115 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10116 code below would make the expression more complex. Change it to a
10117 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10118 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10130 {
10134 boolean_type_node,
10142 }
10146 {
10148 {
10154 }
10157 {
10163 }
10166 {
10172 }
10175 {
10181 }
10182 }
10185 {
10187 /* 0 +p index -> (type)index */
10191 /* PTR +p 0 -> PTR */
10195 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10201 arg1),
10203 arg0)));
10205 /* index +p PTR -> PTR +p index */
10212 /* (PTR +p B) +p A -> PTR +p (B + A) */
10214 {
10215 tree inner;
10224 }
10226 /* PTR_CST +p CST -> CST1 */
10231 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10232 of the array. Loop optimizer sometimes produce this type of
10233 expressions. */
10235 {
10240 }
10245 /* A + (-B) -> A - B */
10251 /* (-A) + B -> B - A */
10260 {
10261 /* Convert ~A + 1 to -A. */
10268 /* ~X + X is -1. */
10271 {
10276 {
10279 }
10280 }
10282 /* X + ~X is -1. */
10285 {
10290 {
10293 }
10294 }
10296 /* X + (X / CST) * -CST is X % CST. */
10301 {
10310 cst0));
10311 }
10312 }
10314 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
10315 same or one. Make sure type is not saturating.
10316 fold_plusminus_mult_expr will re-associate. */
10321 {
10325 }
10328 {
10332 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10333 with a constant, and the two constants have no bits in common,
10334 we should treat this as a BIT_IOR_EXPR since this may produce more
10335 simplifications. */
10343 {
10346 }
10348 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10349 (plus (plus (mult) (mult)) (foo)) so that we can
10350 take advantage of the factoring cases below. */
10357 {
10363 else
10376 parg0),
10378 marg)),
10382 return
10388 parg1)));
10389 }
10390 }
10391 else
10392 {
10393 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10397 /* Likewise if the operands are reversed. */
10401 /* Convert X + -C into X - C. */
10404 {
10410 }
10412 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10413 to __complex__ ( x, y ). This is not the same for SNaNs or
10414 if signed zeros are involved. */
10418 {
10425 {
10429 {
10435 }
10437 {
10443 }
10444 }
10445 }
10453 /* Convert x+x into x*2.0. */
10459 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10460 We associate floats only if the user has specified
10461 -fassociative-math. */
10465 {
10470 {
10471 tree tree0;
10474 }
10475 }
10476 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10477 We associate floats only if the user has specified
10478 -fassociative-math. */
10482 {
10487 {
10488 tree tree0;
10491 }
10492 }
10493 }
10495 bit_rotate:
10496 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10497 is a rotate of A by C1 bits. */
10498 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10499 is a rotate of A by B bits. */
10500 {
10502 tree rtype;
10511 /* Only create rotates in complete modes. Other cases are not
10512 expanded properly. */
10514 {
10530 {
10534 code0 == LSHIFT_EXPR
10538 }
10540 {
10548 TYPE_PRECISION
10552 return
10555 ? LROTATE_EXPR
10559 }
10561 {
10569 TYPE_PRECISION
10573 return fold_convert_loc
10576 ? LROTATE_EXPR
10580 }
10581 }
10582 }
10584 associate:
10585 /* In most languages, can't associate operations on floats through
10586 parentheses. Rather than remember where the parentheses were, we
10587 don't associate floats at all, unless the user has specified
10588 -fassociative-math.
10589 And, we need to make sure type is not saturating. */
10593 {
10598 /* Split both trees into variables, constants, and literals. Then
10599 associate each group together, the constants with literals,
10600 then the result with variables. This increases the chances of
10601 literals being recombined later and of generating relocatable
10602 expressions for the sum of a constant and literal. */
10607 /* With undefined overflow we can only associate constants
10608 with one variable. */
10612 {
10620 /* The only case we can still associate with two variables
10621 is if they are the same, modulo negation. */
10624 }
10626 /* Only do something if we found more than two objects. Otherwise,
10627 nothing has changed and we risk infinite recursion. */
10633 {
10634 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10643 /* Preserve the MINUS_EXPR if the negative part of the literal is
10644 greater than the positive part. Otherwise, the multiplicative
10645 folding code (i.e extract_muldiv) may be fooled in case
10646 unsigned constants are subtracted, like in the following
10647 example: ((X*2 + 4) - 8U)/2. */
10649 {
10653 {
10657 }
10658 else
10659 {
10663 }
10664 }
10666 {
10668 return
10672 else
10673 {
10676 return
10680 }
10681 }
10684 return
10687 }
10688 }
10693 /* Pointer simplifications for subtraction, simple reassociations. */
10695 {
10696 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10699 {
10709 }
10710 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10712 {
10719 }
10720 }
10721 /* A - (-B) -> A + B */
10726 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10737 /* Convert -A - 1 to ~A. */
10746 /* Convert -1 - A to ~A. */
10752 /* X - (X / CST) * CST is X % CST. */
10760 return
10766 {
10772 /* Fold A - (A & B) into ~B & A. */
10775 {
10777 {
10784 }
10786 {
10793 }
10794 }
10796 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10797 any power of 2 minus 1. */
10802 {
10808 {
10812 }
10813 }
10814 }
10816 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10820 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10821 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10822 (-ARG1 + ARG0) reduces to -ARG1. */
10826 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10827 __complex__ ( x, -y ). This is not the same for SNaNs or if
10828 signed zeros are involved. */
10832 {
10839 {
10843 {
10845 arg1r ? arg1r
10850 }
10852 {
10856 arg1i ? arg1i
10859 }
10860 }
10861 }
10863 /* Fold &x - &x. This can happen from &x.foo - &x.
10864 This is unsafe for certain floats even in non-IEEE formats.
10865 In IEEE, it is unsafe because it does wrong for NaNs.
10866 Also note that operand_equal_p is always false if an operand
10867 is volatile. */
10873 /* A - B -> A + (-B) if B is easily negatable. */
10876 /* Avoid this transformation if B is a positive REAL_CST. */
10885 /* Try folding difference of addresses. */
10886 {
10887 HOST_WIDE_INT diff;
10893 }
10895 /* Fold &a[i] - &a[j] to i-j. */
10900 {
10905 {
10913 }
10914 }
10917 && flag_unsafe_math_optimizations
10923 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10924 same or one. Make sure type is not saturating.
10925 fold_plusminus_mult_expr will re-associate. */
10930 {
10934 }
10939 /* (-A) * (-B) -> A * B */
10954 {
10959 /* Transform x * -1 into -x. Make sure to do the negation
10960 on the original operand with conversions not stripped
10961 because we can only strip non-sign-changing conversions. */
10964 /* Transform x * -C into -x * C if x is easily negatable. */
10973 tem);
10975 /* (a * (1 << b)) is (a << b) */
10985 /* (A + A) * C -> A * 2 * C */
11001 {
11004 "occur when simplifying "
11006 WARN_STRICT_OVERFLOW_MISC);
11008 }
11010 /* Optimize z * conj(z) for integer complex numbers. */
11017 }
11018 else
11019 {
11020 /* Maybe fold x * 0 to 0. The expressions aren't the same
11021 when x is NaN, since x * 0 is also NaN. Nor are they the
11022 same in modes with signed zeros, since multiplying a
11023 negative value by 0 gives -0, not +0. */
11028 /* In IEEE floating point, x*1 is not equivalent to x for snans.
11029 Likewise for complex arithmetic with signed zeros. */
11036 /* Transform x * -1.0 into -x. */
11043 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
11044 the result for floating point types due to rounding so it is applied
11045 only if -fassociative-math was specify. */
11050 {
11056 }
11058 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
11060 {
11063 {
11066 }
11067 }
11069 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11070 This is not the same for NaNs or if signed zeros are
11071 involved. */
11077 {
11080 return
11086 return
11091 }
11093 /* Optimize z * conj(z) for floating point complex numbers.
11094 Guarded by flag_unsafe_math_optimizations as non-finite
11095 imaginary components don't produce scalar results. */
11106 {
11110 /* Optimizations of root(...)*root(...). */
11112 {
11117 /* Optimize sqrt(x)*sqrt(x) as x. */
11123 /* Optimize root(x)*root(y) as root(x*y). */
11127 }
11129 /* Optimize expN(x)*expN(y) as expN(x+y). */
11131 {
11137 }
11139 /* Optimizations of pow(...)*pow(...). */
11143 {
11149 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11151 {
11156 }
11158 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11160 {
11165 }
11166 }
11168 /* Optimize tan(x)*cos(x) as sin(x). */
11177 {
11183 }
11185 /* Optimize x*pow(x,c) as pow(x,c+1). */
11189 {
11195 {
11197 REAL_VALUE_TYPE c;
11198 tree arg;
11204 }
11205 }
11207 /* Optimize pow(x,c)*x as pow(x,c+1). */
11211 {
11217 {
11219 REAL_VALUE_TYPE c;
11220 tree arg;
11226 }
11227 }
11229 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
11232 {
11236 {
11239 }
11240 }
11241 }
11242 }
11246 bit_ior:
11254 /* ~X | X is -1. */
11257 {
11261 }
11263 /* X | ~X is -1. */
11266 {
11270 }
11272 /* Canonicalize (X & C1) | C2. */
11276 {
11284 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11290 {
11294 }
11295 else
11296 {
11300 }
11302 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11307 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11308 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11309 mode which allows further optimizations. */
11319 {
11320 unsigned HOST_WIDE_INT mask
11324 {
11328 }
11329 }
11336 arg1);
11337 }
11339 /* (X & Y) | Y is (X, Y). */
11343 /* (X & Y) | X is (Y, X). */
11348 /* X | (X & Y) is (Y, X). */
11353 /* X | (Y & X) is (Y, X). */
11363 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11365 This results in more efficient code for machines without a NAND
11366 instruction. Combine will canonicalize to the first form
11367 which will allow use of NAND instructions provided by the
11368 backend if they exist. */
11371 {
11372 return
11379 }
11381 /* See if this can be simplified into a rotate first. If that
11382 is unsuccessful continue in the association code. */
11393 /* ~X ^ X is -1. */
11396 {
11400 }
11402 /* X ^ ~X is -1. */
11405 {
11409 }
11411 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11412 with a constant, and the two constants have no bits in common,
11413 we should treat this as a BIT_IOR_EXPR since this may produce more
11414 simplifications. */
11422 {
11425 }
11427 /* (X | Y) ^ X -> Y & ~ X*/
11430 {
11433 arg1);
11438 }
11440 /* (Y | X) ^ X -> Y & ~ X*/
11443 {
11446 arg1);
11451 }
11453 /* X ^ (X | Y) -> Y & ~ X*/
11456 {
11459 arg0);
11464 }
11466 /* X ^ (Y | X) -> Y & ~ X*/
11469 {
11472 arg0);
11477 }
11479 /* Convert ~X ^ ~Y to X ^ Y. */
11488 /* Convert ~X ^ C to X ^ ~C. */
11496 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11503 /* Fold (X & Y) ^ Y as ~X & Y. */
11506 {
11511 }
11512 /* Fold (X & Y) ^ X as ~Y & X. */
11516 {
11521 }
11522 /* Fold X ^ (X & Y) as X & ~Y. */
11525 {
11530 }
11531 /* Fold X ^ (Y & X) as ~Y & X. */
11535 {
11540 }
11542 /* See if this can be simplified into a rotate first. If that
11543 is unsuccessful continue in the association code. */
11554 /* ~X & X is always zero. */
11559 /* X & ~X is always zero. */
11564 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11568 {
11574 return
11578 }
11580 /* (X | Y) & Y is (X, Y). */
11584 /* (X | Y) & X is (Y, X). */
11589 /* X & (X | Y) is (Y, X). */
11594 /* X & (Y | X) is (Y, X). */
11600 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11604 {
11610 }
11611 /* Fold ~X & 1 as (X & 1) == 0. */
11614 {
11620 }
11622 /* Fold (X ^ Y) & Y as ~X & Y. */
11625 {
11630 }
11631 /* Fold (X ^ Y) & X as ~Y & X. */
11635 {
11640 }
11641 /* Fold X & (X ^ Y) as X & ~Y. */
11644 {
11649 }
11650 /* Fold X & (Y ^ X) as ~Y & X. */
11654 {
11659 }
11664 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11667 {
11668 unsigned int prec
11674 return
11676 }
11678 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11680 This results in more efficient code for machines without a NOR
11681 instruction. Combine will canonicalize to the first form
11682 which will allow use of NOR instructions provided by the
11683 backend if they exist. */
11686 {
11693 }
11695 /* If arg0 is derived from the address of an object or function, we may
11696 be able to fold this expression using the object or function's
11697 alignment. */
11699 {
11706 /* This works because modulus is a power of 2. If this weren't the
11707 case, we'd have to replace it by its greatest power-of-2
11708 divisor: modulus & -modulus. */
11711 }
11713 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11714 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11715 if the new mask might be further optimized. */
11724 {
11726 unsigned HOST_WIDE_INT mask
11736 {
11739 /* See if more bits can be proven as zero because of
11740 zero extension. */
11743 {
11748 {
11750 /* See if we can shorten the right shift. */
11753 }
11754 }
11758 /* For arithmetic shift if sign bit could be set, zerobits
11759 can contain actually sign bits, so no transformation is
11760 possible, unless MASK masks them all away. In that
11761 case the shift needs to be converted into logical shift. */
11764 {
11767 else
11769 }
11770 }
11772 /* ((X << 16) & 0xff00) is (X, 0). */
11779 {
11782 /* Only do the transformation if NEWMASK is some integer
11783 mode's mask. */
11790 {
11791 tree newmaskt;
11794 {
11800 }
11801 else
11806 }
11807 }
11808 }
11813 /* Don't touch a floating-point divide by zero unless the mode
11814 of the constant can represent infinity. */
11820 /* Optimize A / A to 1.0 if we don't care about
11821 NaNs or Infinities. Skip the transformation
11822 for non-real operands. */
11827 {
11831 }
11833 /* The complex version of the above A / A optimization. */
11836 {
11840 {
11842 /* omit_two_operands will call fold_convert for us. */
11844 }
11845 }
11847 /* (-A) / (-B) -> A / B */
11857 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11862 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11868 /* If ARG1 is a constant, we can convert this to a multiply by the
11869 reciprocal. This does not have the same rounding properties,
11870 so only do this if -freciprocal-math. We can actually
11871 always safely do it if ARG1 is a power of two, but it's hard to
11872 tell if it is or not in a portable manner. */
11874 {
11879 /* Find the reciprocal if optimizing and the result is exact. */
11881 {
11882 REAL_VALUE_TYPE r;
11885 {
11889 }
11890 }
11891 }
11892 /* Convert A/B/C to A/(B*C). */
11899 /* Convert A/(B/C) to (A/B)*C. */
11907 /* Convert C1/(X*C2) into (C1/C2)/X. */
11912 {
11918 }
11921 {
11925 /* Optimize sin(x)/cos(x) as tan(x). */
11931 {
11936 }
11938 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11944 {
11948 {
11953 }
11954 }
11956 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11957 NaNs or Infinities. */
11961 {
11968 {
11973 }
11974 }
11976 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11977 NaNs or Infinities. */
11981 {
11988 {
11992 {
11996 tmp);
11997 }
11998 }
11999 }
12001 /* Optimize pow(x,c)/x as pow(x,c-1). */
12005 {
12011 {
12013 REAL_VALUE_TYPE c;
12014 tree arg;
12020 }
12021 }
12023 /* Optimize a/root(b/c) into a*root(c/b). */
12025 {
12029 {
12038 }
12039 }
12041 /* Optimize x/expN(y) into x*expN(-y). */
12043 {
12050 }
12052 /* Optimize x/pow(y,z) into x*pow(y,-z). */
12056 {
12064 }
12065 }
12070 /* Simplify A / (B << N) where A and B are positive and B is
12071 a power of 2, to A >> (N + log2(B)). */
12076 {
12079 {
12086 WARN_STRICT_OVERFLOW_MISC);
12092 }
12093 }
12095 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
12096 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12102 /* Fall thru */
12111 /* X / -1 is -X. */
12118 /* Convert -A / -B to A / B when the type is signed and overflow is
12119 undefined. */
12123 {
12126 "when distributing negation across "
12128 WARN_STRICT_OVERFLOW_MISC);
12134 }
12138 {
12141 "when distributing negation across "
12143 WARN_STRICT_OVERFLOW_MISC);
12149 }
12151 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12152 operation, EXACT_DIV_EXPR.
12154 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12155 At one time others generated faster code, it's not clear if they do
12156 after the last round to changes to the DIV code in expmed.c. */
12165 {
12169 WARN_STRICT_OVERFLOW_MISC);
12171 }
12179 /* X % 1 is always zero, but be sure to preserve any side
12180 effects in X. */
12184 /* X % 0, return X % 0 unchanged so that we can get the
12185 proper warnings and errors. */
12189 /* 0 % X is always zero, but be sure to preserve any side
12190 effects in X. Place this after checking for X == 0. */
12194 /* X % -1 is zero. */
12201 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12202 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12207 {
12209 /* Also optimize A % (C << N) where C is a power of 2,
12210 to A & ((C << N) - 1). */
12215 {
12220 "occur when simplifying "
12222 WARN_STRICT_OVERFLOW_MISC);
12226 }
12227 }
12229 /* X % -C is the same as X % C. */
12236 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12243 /* X % -Y is the same as X % Y. */
12255 {
12259 WARN_STRICT_OVERFLOW_MISC);
12261 }
12272 /* Optimize -1 >> x for arithmetic right shifts. */
12276 /* ... fall through ... */
12279 shift:
12285 /* Since negative shift count is not well-defined,
12286 don't try to compute it in the compiler. */
12290 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12295 {
12299 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12300 being well defined. */
12302 {
12308 else
12310 }
12314 }
12316 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12317 into x & ((unsigned)-1 >> c) for unsigned types. */
12325 {
12328 tree lshift;
12329 tree arg00;
12332 {
12339 }
12340 }
12342 /* Rewrite an LROTATE_EXPR by a constant into an
12343 RROTATE_EXPR by a new constant. */
12345 {
12350 }
12352 /* If we have a rotate of a bit operation with the rotate count and
12353 the second operand of the bit operation both constant,
12354 permute the two operations. */
12366 /* Two consecutive rotates adding up to the precision of the
12367 type can be ignored. */
12378 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12379 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12380 if the latter can be further optimized. */
12385 {
12389 arg1);
12393 arg1);
12397 }
12425 /* Note that the operands of this must be ints
12426 and their values must be 0 or 1.
12427 ("true" is a fixed value perhaps depending on the language.) */
12428 /* If first arg is constant zero, return it. */
12432 /* If either arg is constant true, drop it. */
12436 /* Preserve sequence points. */
12439 /* If second arg is constant zero, result is zero, but first arg
12440 must be evaluated. */
12443 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12444 case will be handled here. */
12448 /* !X && X is always false. */
12452 /* X && !X is always false. */
12457 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12458 means A >= Y && A != MAX, but in this case we know that
12459 A < X <= MAX. */
12463 {
12471 }
12473 truth_andor:
12474 /* We only do these simplifications if we are optimizing. */
12478 /* Check for things like (A || B) && (A || C). We can convert this
12479 to A || (B && C). Note that either operator can be any of the four
12480 truth and/or operations and the transformation will still be
12481 valid. Also note that we only care about order for the
12482 ANDIF and ORIF operators. If B contains side effects, this
12483 might change the truth-value of A. */
12490 {
12510 /* This case if tricky because we must either have commutative
12511 operators or else A10 must not have side-effects. */
12517 a01);
12518 }
12520 /* See if we can build a range comparison. */
12524 /* Check for the possibility of merging component references. If our
12525 lhs is another similar operation, try to merge its rhs with our
12526 rhs. Then try to merge our lhs and rhs. */
12538 /* Note that the operands of this must be ints
12539 and their values must be 0 or true.
12540 ("true" is a fixed value perhaps depending on the language.) */
12541 /* If first arg is constant true, return it. */
12545 /* If either arg is constant zero, drop it. */
12549 /* Preserve sequence points. */
12552 /* If second arg is constant true, result is true, but we must
12553 evaluate first arg. */
12556 /* Likewise for first arg, but note this only occurs here for
12557 TRUTH_OR_EXPR. */
12561 /* !X || X is always true. */
12565 /* X || !X is always true. */
12573 /* If the second arg is constant zero, drop it. */
12576 /* If the second arg is constant true, this is a logical inversion. */
12578 {
12579 /* Only call invert_truthvalue if operand is a truth value. */
12582 else
12585 }
12586 /* Identical arguments cancel to zero. */
12590 /* !X ^ X is always true. */
12595 /* X ^ !X is always true. */
12608 /* bool_var != 0 becomes bool_var. */
12613 /* bool_var == 1 becomes bool_var. */
12618 /* bool_var != 1 becomes !bool_var. */
12624 /* bool_var == 0 becomes !bool_var. */
12630 /* !exp != 0 becomes !exp */
12635 /* If this is an equality comparison of the address of two non-weak,
12636 unaliased symbols neither of which are extern (since we do not
12637 have access to attributes for externs), then we know the result. */
12650 {
12651 /* We know that we're looking at the address of two
12652 non-weak, unaliased, static _DECL nodes.
12654 It is both wasteful and incorrect to call operand_equal_p
12655 to compare the two ADDR_EXPR nodes. It is wasteful in that
12656 all we need to do is test pointer equality for the arguments
12657 to the two ADDR_EXPR nodes. It is incorrect to use
12658 operand_equal_p as that function is NOT equivalent to a
12659 C equality test. It can in fact return false for two
12660 objects which would test as equal using the C equality
12661 operator. */
12665 type);
12666 }
12668 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12669 a MINUS_EXPR of a constant, we can convert it into a comparison with
12670 a revised constant as long as no overflow occurs. */
12678 arg1),
12683 /* Similarly for a NEGATE_EXPR. */
12691 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12699 arg1),
12702 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12709 {
12713 val,
12717 }
12719 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12724 {
12726 code == NE_EXPR
12729 }
12731 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12732 for !=. Don't do this for ordered comparisons due to overflow. */
12738 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12743 /* If this is an EQ or NE comparison with zero and ARG0 is
12744 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12745 two operations, but the latter can be done in one less insn
12746 on machines that have only two-operand insns or on which a
12747 constant cannot be the first operand. */
12750 {
12755 {
12762 arg1);
12763 }
12766 {
12773 arg1);
12774 }
12775 }
12777 /* If this is an NE or EQ comparison of zero against the result of a
12778 signed MOD operation whose second operand is a power of 2, make
12779 the MOD operation unsigned since it is simpler and equivalent. */
12787 {
12797 }
12799 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12800 C1 is a valid shift constant, and C2 is a power of two, i.e.
12801 a single bit. */
12805 == INTEGER_CST
12808 {
12813 /* Check for a valid shift count. */
12816 {
12820 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12821 can be rewritten as (X & (C2 << C1)) != 0. */
12823 {
12827 }
12828 /* Otherwise, for signed (arithmetic) shifts,
12829 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12830 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12834 /* Otherwise, of unsigned (logical) shifts,
12835 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12836 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12837 else
12841 arg000);
12842 }
12843 }
12845 /* If this is an NE comparison of zero with an AND of one, remove the
12846 comparison since the AND will give the correct value. */
12853 /* If we have (A & C) == C where C is a power of 2, convert this into
12854 (A & C) != 0. Similarly for NE_EXPR. */
12860 integer_zero_node));
12862 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12863 bit, then fold the expression into A < 0 or A >= 0. */
12868 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12869 Similarly for NE_EXPR. */
12873 {
12882 }
12884 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12885 Similarly for NE_EXPR. */
12889 {
12896 }
12898 /* If this is a comparison of a field, we may be able to simplify it. */
12901 /* Handle the constant case even without -O
12902 to make sure the warnings are given. */
12904 {
12908 }
12910 /* Optimize comparisons of strlen vs zero to a compare of the
12911 first character of the string vs zero. To wit,
12912 strlen(ptr) == 0 => *ptr == 0
12913 strlen(ptr) != 0 => *ptr != 0
12914 Other cases should reduce to one of these two (or a constant)
12915 due to the return value of strlen being unsigned. */
12918 {
12926 {
12931 }
12932 }
12934 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12935 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12939 {
12946 {
12948 {
12951 }
12954 }
12955 }
12957 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12963 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12968 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12975 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12983 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12984 (X & C) == 0 when C is a single bit. */
12989 {
12995 }
12997 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12998 constant C is a power of two, i.e. a single bit. */
13005 {
13009 }
13011 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
13012 when is C is a power of two, i.e. a single bit. */
13019 {
13025 }
13029 {
13032 }
13034 /* Fold -X op -Y as X op Y, where op is eq/ne. */
13041 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
13044 {
13057 arg01),
13066 arg01),
13075 arg00),
13084 arg00),
13086 }
13090 {
13097 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
13098 operand_equal_p guarantees no side-effects so we don't need
13099 to use omit_one_operand on Z. */
13109 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13117 arg10);
13118 }
13120 /* Attempt to simplify equality/inequality comparisons of complex
13121 values. Only lower the comparison if the result is known or
13122 can be simplified to a single scalar comparison. */
13127 {
13132 {
13135 }
13136 else
13137 {
13140 }
13143 {
13146 }
13147 else
13148 {
13151 }
13155 {
13157 {
13162 }
13163 else
13164 {
13169 }
13170 }
13174 {
13176 {
13181 }
13182 else
13183 {
13188 }
13189 }
13190 }
13202 /* Transform comparisons of the form X +- C CMP X. */
13209 {
13216 else
13219 /* (X - c) > X becomes false. */
13223 {
13227 "occur when assuming that (X - c) > X "
13229 WARN_STRICT_OVERFLOW_ALL);
13231 }
13233 /* Likewise (X + c) < X becomes false. */
13237 {
13241 "occur when assuming that "
13243 WARN_STRICT_OVERFLOW_ALL);
13245 }
13247 /* Convert (X - c) <= X to true. */
13252 {
13256 "occur when assuming that "
13258 WARN_STRICT_OVERFLOW_ALL);
13260 }
13262 /* Convert (X + c) >= X to true. */
13267 {
13271 "occur when assuming that "
13273 WARN_STRICT_OVERFLOW_ALL);
13275 }
13278 {
13279 /* Convert X + c > X and X - c < X to true for integers. */
13283 {
13286 "not occur when assuming that "
13288 WARN_STRICT_OVERFLOW_ALL);
13290 }
13295 {
13298 "not occur when assuming that "
13300 WARN_STRICT_OVERFLOW_ALL);
13302 }
13304 /* Convert X + c <= X and X - c >= X to false for integers. */
13308 {
13311 "not occur when assuming that "
13313 WARN_STRICT_OVERFLOW_ALL);
13315 }
13320 {
13323 "not occur when assuming that "
13325 WARN_STRICT_OVERFLOW_ALL);
13327 }
13328 }
13329 }
13331 /* Comparisons with the highest or lowest possible integer of
13332 the specified precision will have known values. */
13333 {
13340 {
13341 HOST_WIDE_INT signed_max_hi;
13346 {
13353 {
13357 }
13358 else
13359 {
13363 }
13364 }
13365 else
13366 {
13375 {
13378 }
13379 else
13380 {
13383 }
13384 }
13389 {
13402 /* The GE_EXPR and LT_EXPR cases above are not normally
13403 reached because of previous transformations. */
13407 }
13409 == max_hi
13412 {
13419 arg1);
13425 arg0),
13426 arg1);
13429 }
13431 == min_hi
13434 {
13449 }
13451 == min_hi
13454 {
13460 arg1);
13465 arg0),
13466 arg1);
13469 }
13474 /* We will flip the signedness of the comparison operator
13475 associated with the mode of arg1, so the sign bit is
13476 specified by this mode. Check that arg1 is the signed
13477 max associated with this sign bit. */
13479 /* signed_type does not work on pointer types. */
13481 {
13482 /* The following case also applies to X < signed_max+1
13483 and X >= signed_max+1 because previous transformations. */
13485 {
13486 tree st;
13492 }
13493 }
13494 }
13495 }
13497 /* If we are comparing an ABS_EXPR with a constant, we can
13498 convert all the cases into explicit comparisons, but they may
13499 well not be faster than doing the ABS and one comparison.
13500 But ABS (X) <= C is a range comparison, which becomes a subtraction
13501 and a comparison, and is probably faster. */
13515 /* Convert ABS_EXPR<x> >= 0 to true. */
13522 {
13525 "when simplifying comparison of "
13527 WARN_STRICT_OVERFLOW_CONDITIONAL);
13529 }
13531 /* Convert ABS_EXPR<x> < 0 to false. */
13536 {
13539 "when simplifying comparison of "
13541 WARN_STRICT_OVERFLOW_CONDITIONAL);
13543 }
13545 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13546 and similarly for >= into !=. */
13551 {
13557 }
13564 {
13573 }
13586 {
13590 }
13592 /* If the first operand is NaN, the result is constant. */
13596 {
13598 ? integer_zero_node
13601 }
13603 /* If the second operand is NaN, the result is constant. */
13607 {
13609 ? integer_zero_node
13612 }
13614 /* Simplify unordered comparison of something with itself. */
13620 && !flag_trapping_math
13624 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13625 {
13637 }
13642 /* When pedantic, a compound expression can be neither an lvalue
13643 nor an integer constant expression. */
13646 /* Don't let (0, 0) be null pointer constant. */
13660 /* An ASSERT_EXPR should never be passed to fold_binary. */
13666 fold_binary_exit:
13669 }
13671 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13672 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13673 of GOTO_EXPR. */
13675 static tree
13677 {
13679 {
13686 /* ... fall through ... */
13690 }
13691 }
13693 /* Return whether the sub-tree ST contains a label which is accessible from
13694 outside the sub-tree. */
13696 static bool
13698 {
13699 return
13701 }
13703 /* Fold a ternary expression of code CODE and type TYPE with operands
13704 OP0, OP1, and OP2. Return the folded expression if folding is
13705 successful. Otherwise, return NULL_TREE. */
13707 tree
13710 {
13711 tree tem;
13718 /* Strip any conversions that don't change the mode. This is safe
13719 for every expression, except for a comparison expression because
13720 its signedness is derived from its operands. So, in the latter
13721 case, only strip conversions that don't change the signedness.
13723 Note that this is done as an internal manipulation within the
13724 constant folder, in order to find the simplest representation of
13725 the arguments so that their form can be studied. In any cases,
13726 the appropriate type conversions should be put back in the tree
13727 that will get out of the constant folder. */
13729 {
13732 }
13735 {
13738 }
13741 {
13745 {
13751 }
13755 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13756 so all simple results must be passed through pedantic_non_lvalue. */
13758 {
13761 /* Only optimize constant conditions when the selected branch
13762 has the same type as the COND_EXPR. This avoids optimizing
13763 away "c ? x : throw", where the throw has a void type.
13764 Avoid throwing away that operand which contains label. */
13771 }
13775 /* If we have A op B ? A : C, we may be able to convert this to a
13776 simpler expression, depending on the operation and the values
13777 of B and C. Signed zeros prevent all of these transformations,
13778 for reasons given above each one.
13780 Also try swapping the arguments and inverting the conditional. */
13785 {
13789 }
13793 op2,
13796 {
13799 {
13803 }
13804 }
13806 /* If the second operand is simpler than the third, swap them
13807 since that produces better jump optimization results. */
13810 {
13811 /* See if this can be inverted. If it can't, possibly because
13812 it was a floating-point inequality comparison, don't do
13813 anything. */
13817 }
13819 /* Convert A ? 1 : 0 to simply A. */
13822 /* If we try to convert OP0 to our type, the
13823 call to fold will try to move the conversion inside
13824 a COND, which will recurse. In that case, the COND_EXPR
13825 is probably the best choice, so leave it alone. */
13829 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13830 over COND_EXPR in cases such as floating point comparisons. */
13837 arg0)));
13839 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13844 {
13845 /* sign_bit_p only checks ARG1 bits within A's precision.
13846 If <sign bit of A> has wider type than A, bits outside
13847 of A's precision in <sign bit of A> need to be checked.
13848 If they are all 0, this optimization needs to be done
13849 in unsigned A's type, if they are all 1 in signed A's type,
13850 otherwise this can't be done. */
13855 {
13857 HOST_WIDE_INT mask_hi;
13859 tree tem_type;
13867 {
13871 }
13872 else
13873 {
13877 }
13879 {
13883 }
13884 else
13890 {
13893 }
13896 {
13899 }
13900 else
13902 }
13905 return
13911 arg1)));
13912 }
13914 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13915 already handled above. */
13920 {
13929 }
13931 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13932 is probably obsolete because the first operand should be a
13933 truth value (that's why we have the two cases above), but let's
13934 leave it in until we can confirm this for all front-ends. */
13946 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13952 arg1);
13954 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13958 {
13959 /* Only perform transformation if ARG0 is easily inverted. */
13964 arg1);
13965 }
13967 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13971 {
13972 /* Only perform transformation if ARG0 is easily inverted. */
13977 op2);
13978 }
13980 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13986 op2);
13991 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13992 of fold_ternary on them. */
13999 {
14008 {
14013 else
14014 {
14016 tree value;
14020 }
14025 else
14027 }
14028 }
14030 /* A bit-field-ref that referenced the full argument can be stripped. */
14041 }
14043 /* Perform constant folding and related simplification of EXPR.
14044 The related simplifications include x*1 => x, x*0 => 0, etc.,
14045 and application of the associative law.
14046 NOP_EXPR conversions may be removed freely (as long as we
14047 are careful not to change the type of the overall expression).
14048 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14049 but we can constant-fold them if they have constant operands. */
14051 #ifdef ENABLE_FOLD_CHECKING
14052 # define fold(x) fold_1 (x)
14054 static
14055 #endif
14056 tree
14058 {
14062 tree tem;
14065 /* Return right away if a constant. */
14069 /* CALL_EXPR-like objects with variable numbers of operands are
14070 treated specially. */
14072 {
14074 {
14077 }
14079 }
14082 {
14087 {
14105 }
14106 }
14109 {
14111 {
14118 {
14123 /* Find a matching index by means of a binary search. */
14125 {
14141 else
14143 }
14144 }
14147 }
14155 }
14157 #ifdef ENABLE_FOLD_CHECKING
14158 #undef fold
14164 /* When --enable-checking=fold, compute a digest of expr before
14165 and after actual fold call to see if fold did not accidentally
14166 change original expr. */
14168 tree
14170 {
14171 tree ret;
14174 htab_t ht;
14193 }
14195 void
14197 {
14200 htab_t ht;
14210 }
14212 static void
14214 {
14216 }
14218 static void
14220 {
14226 recursive_label:
14240 {
14241 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14245 }
14252 {
14253 /* Allow these fields to be modified. */
14254 tree tmp;
14262 {
14265 }
14266 }
14275 {
14278 {
14292 }
14296 {
14309 }
14326 {
14332 }
14337 {
14341 }
14352 {
14355 }
14365 }
14366 }
14368 /* Helper function for outputting the checksum of a tree T. When
14369 debugging with gdb, you can "define mynext" to be "next" followed
14370 by "call debug_fold_checksum (op0)", then just trace down till the
14371 outputs differ. */
14373 void
14375 {
14390 }
14392 #endif
14394 /* Fold a unary tree expression with code CODE of type TYPE with an
14395 operand OP0. LOC is the location of the resulting expression.
14396 Return a folded expression if successful. Otherwise, return a tree
14397 expression with code CODE of type TYPE with an operand OP0. */
14399 tree
14402 {
14403 tree tem;
14404 #ifdef ENABLE_FOLD_CHECKING
14407 htab_t ht;
14414 #endif
14418 {
14421 }
14423 #ifdef ENABLE_FOLD_CHECKING
14431 #endif
14433 }
14435 /* Fold a binary tree expression with code CODE of type TYPE with
14436 operands OP0 and OP1. LOC is the location of the resulting
14437 expression. Return a folded expression if successful. Otherwise,
14438 return a tree expression with code CODE of type TYPE with operands
14439 OP0 and OP1. */
14441 tree
14444 MEM_STAT_DECL)
14445 {
14446 tree tem;
14447 #ifdef ENABLE_FOLD_CHECKING
14453 htab_t ht;
14465 #endif
14469 {
14472 }
14474 #ifdef ENABLE_FOLD_CHECKING
14490 #endif
14492 }
14494 /* Fold a ternary tree expression with code CODE of type TYPE with
14495 operands OP0, OP1, and OP2. Return a folded expression if
14496 successful. Otherwise, return a tree expression with code CODE of
14497 type TYPE with operands OP0, OP1, and OP2. */
14499 tree
14502 {
14503 tree tem;
14504 #ifdef ENABLE_FOLD_CHECKING
14512 htab_t ht;
14529 #endif
14534 {
14537 }
14539 #ifdef ENABLE_FOLD_CHECKING
14563 #endif
14565 }
14567 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14568 arguments in ARGARRAY, and a null static chain.
14569 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14570 of type TYPE from the given operands as constructed by build_call_array. */
14572 tree
14575 {
14576 tree tem;
14577 #ifdef ENABLE_FOLD_CHECKING
14583 htab_t ht;
14597 #endif
14601 #ifdef ENABLE_FOLD_CHECKING
14618 #endif
14620 }
14622 /* Perform constant folding and related simplification of initializer
14623 expression EXPR. These behave identically to "fold_buildN" but ignore
14624 potential run-time traps and exceptions that fold must preserve. */
14626 #define START_FOLD_INIT \
14627 int saved_signaling_nans = flag_signaling_nans;\
14628 int saved_trapping_math = flag_trapping_math;\
14629 int saved_rounding_math = flag_rounding_math;\
14630 int saved_trapv = flag_trapv;\
14631 int saved_folding_initializer = folding_initializer;\
14632 flag_signaling_nans = 0;\
14633 flag_trapping_math = 0;\
14634 flag_rounding_math = 0;\
14635 flag_trapv = 0;\
14636 folding_initializer = 1;
14638 #define END_FOLD_INIT \
14639 flag_signaling_nans = saved_signaling_nans;\
14640 flag_trapping_math = saved_trapping_math;\
14641 flag_rounding_math = saved_rounding_math;\
14642 flag_trapv = saved_trapv;\
14643 folding_initializer = saved_folding_initializer;
14645 tree
14648 {
14649 tree result;
14650 START_FOLD_INIT;
14654 END_FOLD_INIT;
14656 }
14658 tree
14661 {
14662 tree result;
14663 START_FOLD_INIT;
14667 END_FOLD_INIT;
14669 }
14671 tree
14674 {
14675 tree result;
14676 START_FOLD_INIT;
14680 END_FOLD_INIT;
14682 }
14684 tree
14687 {
14688 tree result;
14689 START_FOLD_INIT;
14693 END_FOLD_INIT;
14695 }
14697 #undef START_FOLD_INIT
14698 #undef END_FOLD_INIT
14700 /* Determine if first argument is a multiple of second argument. Return 0 if
14701 it is not, or we cannot easily determined it to be.
14703 An example of the sort of thing we care about (at this point; this routine
14704 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14705 fold cases do now) is discovering that
14707 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14709 is a multiple of
14711 SAVE_EXPR (J * 8)
14713 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14715 This code also handles discovering that
14717 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14719 is a multiple of 8 so we don't have to worry about dealing with a
14720 possible remainder.
14722 Note that we *look* inside a SAVE_EXPR only to determine how it was
14723 calculated; it is not safe for fold to do much of anything else with the
14724 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14725 at run time. For example, the latter example above *cannot* be implemented
14726 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14727 evaluation time of the original SAVE_EXPR is not necessarily the same at
14728 the time the new expression is evaluated. The only optimization of this
14729 sort that would be valid is changing
14731 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14733 divided by 8 to
14735 SAVE_EXPR (I) * SAVE_EXPR (J)
14737 (where the same SAVE_EXPR (J) is used in the original and the
14738 transformed version). */
14740 int
14742 {
14750 {
14752 /* Bitwise and provides a power of two multiple. If the mask is
14753 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14756 /* FALLTHRU */
14769 {
14773 /* const_binop may not detect overflow correctly,
14774 so check for it explicitly here. */
14780 size_one_node,
14784 }
14788 /* Can't handle conversions from non-integral or wider integral type. */
14794 /* .. fall through ... */
14811 }
14812 }
14814 /* Return true if CODE or TYPE is known to be non-negative. */
14816 static bool
14818 {
14821 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14822 have a signed:1 type (where the value is -1 and 0). */
14825 }
14827 /* Return true if (CODE OP0) is known to be non-negative. If the return
14828 value is based on the assumption that signed overflow is undefined,
14829 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14830 *STRICT_OVERFLOW_P. */
14832 bool
14835 {
14840 {
14842 /* We can't return 1 if flag_wrapv is set because
14843 ABS_EXPR<INT_MIN> = INT_MIN. */
14847 {
14850 }
14857 strict_overflow_p);
14860 {
14865 {
14868 strict_overflow_p);
14870 {
14874 strict_overflow_p);
14875 }
14876 }
14878 {
14881 strict_overflow_p);
14885 }
14886 }
14891 }
14893 /* We don't know sign of `t', so be conservative and return false. */
14895 }
14897 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14898 value is based on the assumption that signed overflow is undefined,
14899 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14900 *STRICT_OVERFLOW_P. */
14902 bool
14905 {
14910 {
14915 strict_overflow_p)
14917 strict_overflow_p));
14919 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14920 both unsigned and at least 2 bits shorter than the result. */
14924 {
14929 {
14933 }
14934 }
14939 {
14940 /* x * x for floating point x is always non-negative. */
14944 strict_overflow_p)
14946 strict_overflow_p));
14947 }
14949 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14950 both unsigned and their total bits is shorter than the result. */
14954 {
14973 {
14983 }
14984 }
14990 strict_overflow_p)
14992 strict_overflow_p));
15003 strict_overflow_p)
15005 strict_overflow_p));
15012 strict_overflow_p);
15015 }
15017 /* We don't know sign of `t', so be conservative and return false. */
15019 }
15021 /* Return true if T is known to be non-negative. If the return
15022 value is based on the assumption that signed overflow is undefined,
15023 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15024 *STRICT_OVERFLOW_P. */
15026 bool
15028 {
15033 {
15045 strict_overflow_p)
15047 strict_overflow_p));
15051 }
15052 /* We don't know sign of `t', so be conservative and return false. */
15054 }
15056 /* Return true if T is known to be non-negative. If the return
15057 value is based on the assumption that signed overflow is undefined,
15058 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15059 *STRICT_OVERFLOW_P. */
15061 bool
15064 {
15067 {
15085 /* Always true. */
15089 /* sqrt(-0.0) is -0.0. */
15093 strict_overflow_p);
15126 /* True if the 1st argument is nonnegative. */
15128 strict_overflow_p);
15131 /* True if the 1st OR 2nd arguments are nonnegative. */
15133 strict_overflow_p)
15135 strict_overflow_p)));
15138 /* True if the 1st AND 2nd arguments are nonnegative. */
15140 strict_overflow_p)
15142 strict_overflow_p)));
15145 /* True if the 2nd argument is nonnegative. */
15147 strict_overflow_p);
15150 /* True if the 1st argument is nonnegative or the second
15151 argument is an even integer. */
15156 strict_overflow_p);
15159 /* True if the 1st argument is nonnegative or the second
15160 argument is an even integer valued real. */
15162 {
15163 REAL_VALUE_TYPE c;
15164 HOST_WIDE_INT n;
15169 {
15170 REAL_VALUE_TYPE cint;
15175 }
15176 }
15178 strict_overflow_p);
15182 }
15184 type);
15185 }
15187 /* Return true if T is known to be non-negative. If the return
15188 value is based on the assumption that signed overflow is undefined,
15189 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15190 *STRICT_OVERFLOW_P. */
15192 bool
15194 {
15200 {
15202 {
15206 /* If the initializer is non-void, then it's a normal expression
15207 that will be assigned to the slot. */
15211 /* Otherwise, the initializer sets the slot in some way. One common
15212 way is an assignment statement at the end of the initializer. */
15214 {
15222 else
15224 }
15228 strict_overflow_p);
15231 }
15234 {
15240 arg0,
15241 arg1,
15242 strict_overflow_p);
15243 }
15247 strict_overflow_p);
15250 strict_overflow_p);
15253 strict_overflow_p);
15258 }
15260 /* We don't know sign of `t', so be conservative and return false. */
15262 }
15264 /* Return true if T is known to be non-negative. If the return
15265 value is based on the assumption that signed overflow is undefined,
15266 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15267 *STRICT_OVERFLOW_P. */
15269 bool
15271 {
15278 {
15285 strict_overflow_p);
15291 strict_overflow_p);
15300 }
15303 {
15311 strict_overflow_p);
15316 strict_overflow_p);
15329 }
15330 }
15332 /* Return true if `t' is known to be non-negative. Handle warnings
15333 about undefined signed overflow. */
15335 bool
15337 {
15344 "determining that expression is always "
15346 WARN_STRICT_OVERFLOW_MISC);
15348 }
15351 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15352 For floating point we further ensure that T is not denormal.
15353 Similar logic is present in nonzero_address in rtlanal.h.
15355 If the return value is based on the assumption that signed overflow
15356 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15357 change *STRICT_OVERFLOW_P. */
15359 bool
15362 {
15364 {
15367 strict_overflow_p);
15370 {
15376 strict_overflow_p));
15377 }
15382 strict_overflow_p);
15386 }
15389 }
15391 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15392 For floating point we further ensure that T is not denormal.
15393 Similar logic is present in nonzero_address in rtlanal.h.
15395 If the return value is based on the assumption that signed overflow
15396 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15397 change *STRICT_OVERFLOW_P. */
15399 bool
15401 tree type,
15402 tree op0,
15404 {
15407 {
15411 {
15412 /* With the presence of negative values it is hard
15413 to say something. */
15420 /* One of operands must be positive and the other non-negative. */
15421 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15422 overflows, on a twos-complement machine the sum of two
15423 nonnegative numbers can never be zero. */
15425 strict_overflow_p)
15427 strict_overflow_p));
15428 }
15433 {
15435 strict_overflow_p)
15437 strict_overflow_p))
15438 {
15441 }
15442 }
15451 {
15454 }
15461 {
15465 /* When both operands are nonzero, then MAX must be too. */
15467 strict_overflow_p))
15470 /* MAX where operand 0 is positive is positive. */
15472 strict_overflow_p);
15473 }
15474 /* MAX where operand 1 is positive is positive. */
15479 {
15483 }
15488 strict_overflow_p)
15490 strict_overflow_p));
15494 }
15497 }
15499 /* Return true when T is an address and is known to be nonzero.
15500 For floating point we further ensure that T is not denormal.
15501 Similar logic is present in nonzero_address in rtlanal.h.
15503 If the return value is based on the assumption that signed overflow
15504 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15505 change *STRICT_OVERFLOW_P. */
15507 bool
15509 {
15512 {
15517 {
15523 /* Weak declarations may link to NULL. Other things may also be NULL
15524 so protect with -fdelete-null-pointer-checks; but not variables
15525 allocated on the stack. */
15527 && (flag_delete_null_pointer_checks
15531 /* Constants are never weak. */
15536 }
15544 {
15548 }
15553 }
15555 }
15557 /* Return true when T is an address and is known to be nonzero.
15558 For floating point we further ensure that T is not denormal.
15559 Similar logic is present in nonzero_address in rtlanal.h.
15561 If the return value is based on the assumption that signed overflow
15562 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15563 change *STRICT_OVERFLOW_P. */
15565 bool
15567 {
15571 /* Doing something useful for floating point would need more work. */
15577 {
15580 strict_overflow_p);
15586 strict_overflow_p);
15594 }
15597 {
15600 strict_overflow_p);
15608 strict_overflow_p);
15623 strict_overflow_p);
15627 strict_overflow_p);
15634 }
15636 }
15638 /* Return true when T is an address and is known to be nonzero.
15639 Handle warnings about undefined signed overflow. */
15641 bool
15643 {
15650 "determining that expression is always "
15652 WARN_STRICT_OVERFLOW_MISC);
15654 }
15656 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15657 attempt to fold the expression to a constant without modifying TYPE,
15658 OP0 or OP1.
15660 If the expression could be simplified to a constant, then return
15661 the constant. If the expression would not be simplified to a
15662 constant, then return NULL_TREE. */
15664 tree
15666 {
15669 }
15671 /* Given the components of a unary expression CODE, TYPE and OP0,
15672 attempt to fold the expression to a constant without modifying
15673 TYPE or OP0.
15675 If the expression could be simplified to a constant, then return
15676 the constant. If the expression would not be simplified to a
15677 constant, then return NULL_TREE. */
15679 tree
15681 {
15684 }
15686 /* If EXP represents referencing an element in a constant string
15687 (either via pointer arithmetic or array indexing), return the
15688 tree representing the value accessed, otherwise return NULL. */
15690 tree
15692 {
15696 {
15698 tree index;
15699 tree string;
15704 else
15705 {
15709 /* Optimize the special-case of a zero lower bound.
15711 We convert the low_bound to sizetype to avoid some problems
15712 with constant folding. (E.g. suppose the lower bound is 1,
15713 and its mode is QI. Without the conversion,l (ARRAY
15714 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15715 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15721 }
15734 }
15736 }
15738 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15739 an integer constant, real, or fixed-point constant.
15741 TYPE is the type of the result. */
15743 static tree
15745 {
15749 {
15751 {
15753 HOST_WIDE_INT high;
15761 }
15768 {
15769 FIXED_VALUE_TYPE f;
15774 /* Propagate overflow flags. */
15778 }
15782 }
15785 }
15787 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15788 an integer constant or real constant.
15790 TYPE is the type of the result. */
15792 tree
15794 {
15798 {
15800 /* If the value is unsigned, then the absolute value is
15801 the same as the ordinary value. */
15804 /* Similarly, if the value is non-negative. */
15807 /* If the value is negative, then the absolute value is
15808 its negation. */
15809 else
15810 {
15812 HOST_WIDE_INT high;
15818 }
15824 else
15830 }
15833 }
15835 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15836 constant. TYPE is the type of the result. */
15838 static tree
15840 {
15850 }
15852 /* Given CODE, a relational operator, the target type, TYPE and two
15853 constant operands OP0 and OP1, return the result of the
15854 relational operation. If the result is not a compile time
15855 constant, then return NULL_TREE. */
15857 static tree
15859 {
15862 /* From here on, the only cases we handle are when the result is
15863 known to be a constant. */
15866 {
15870 /* Handle the cases where either operand is a NaN. */
15872 {
15874 {
15902 }
15905 }
15908 }
15911 {
15915 }
15917 /* Handle equality/inequality of complex constants. */
15919 {
15930 else
15932 }
15934 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15936 To compute GT, swap the arguments and do LT.
15937 To compute GE, do LT and invert the result.
15938 To compute LE, swap the arguments, do LT and invert the result.
15939 To compute NE, do EQ and invert the result.
15941 Therefore, the code below must handle only EQ and LT. */
15944 {
15949 }
15951 /* Note that it is safe to invert for real values here because we
15952 have already handled the one case that it matters. */
15956 {
15959 }
15961 /* Compute a result for LT or EQ if args permit;
15962 Otherwise return T. */
15964 {
15969 else
15971 }
15972 else
15978 }
15980 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15981 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15982 itself. */
15984 tree
15986 {
15987 /* If the expression does not have side effects then we don't have to wrap
15988 it with a cleanup point expression. */
15992 /* If the expression is a return, check to see if the expression inside the
15993 return has no side effects or the right hand side of the modify expression
15994 inside the return. If either don't have side effects set we don't need to
15995 wrap the expression in a cleanup point expression. Note we don't check the
15996 left hand side of the modify because it should always be a return decl. */
15998 {
16005 }
16008 }
16010 /* Given a pointer value OP0 and a type TYPE, return a simplified version
16011 of an indirection through OP0, or NULL_TREE if no simplification is
16012 possible. */
16014 tree
16016 {
16018 tree subtype;
16026 {
16029 /* *&CONST_DECL -> to the value of the const decl. */
16032 /* *&p => p; make sure to handle *&"str"[cst] here. */
16034 {
16038 else
16040 }
16041 /* *(foo *)&fooarray => fooarray[0] */
16044 {
16052 }
16053 /* *(foo *)&complexfoo => __real__ complexfoo */
16057 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16060 {
16064 }
16065 }
16067 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16070 {
16073 tree op00type;
16080 {
16092 }
16093 }
16096 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16099 {
16102 tree op00type;
16109 {
16114 }
16115 }
16117 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16120 {
16121 tree type_domain;
16130 }
16133 }
16135 /* Builds an expression for an indirection through T, simplifying some
16136 cases. */
16138 tree
16140 {
16150 }
16152 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16154 tree
16156 {
16161 else
16163 }
16165 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16166 whose result is ignored. The type of the returned tree need not be
16167 the same as the original expression. */
16169 tree
16171 {
16177 {
16188 else
16194 {
16210 }
16215 }
16216 }
16218 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
16219 This can only be applied to objects of a sizetype. */
16221 tree
16223 {
16230 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16231 have to do anything. Only do this when we are not given a const,
16232 because in that case, this check is more expensive than just
16233 doing it. */
16235 {
16240 }
16242 /* If divisor is a power of two, simplify this to bit manipulation. */
16244 {
16246 {
16259 {
16260 high++;
16263 }
16267 }
16268 else
16269 {
16270 tree t;
16276 }
16277 }
16278 else
16279 {
16284 }
16287 }
16289 /* Likewise, but round down. */
16291 tree
16293 {
16300 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16301 have to do anything. Only do this when we are not given a const,
16302 because in that case, this check is more expensive than just
16303 doing it. */
16305 {
16310 }
16312 /* If divisor is a power of two, simplify this to bit manipulation. */
16314 {
16315 tree t;
16319 }
16320 else
16321 {
16326 }
16329 }
16331 /* Returns the pointer to the base of the object addressed by EXP and
16332 extracts the information about the offset of the access, storing it
16333 to PBITPOS and POFFSET. */
16335 static tree
16338 {
16339 tree core;
16342 HOST_WIDE_INT bitsize;
16346 {
16351 }
16352 else
16353 {
16357 }
16360 }
16362 /* Returns true if addresses of E1 and E2 differ by a constant, false
16363 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16365 bool
16367 {
16381 {
16391 }
16393 {
16394 /* If only one of the offsets is non-constant, the difference cannot
16395 be a constant. */
16397 }
16398 else
16403 }
16405 /* Simplify the floating point expression EXP when the sign of the
16406 result is not significant. Return NULL_TREE if no simplification
16407 is possible. */
16409 tree
16411 {
16416 {
16452 {
16455 {
16457 /* Strip copysign function call, return the 1st argument. */
16463 /* Strip sign ops from the argument of "odd" math functions. */
16465 {
16469 }
16471 }
16472 }
16477 }
16479 }