| blob | 292b89f94961274532569b11c99ab4093131f246 |
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;
340 else
342 }
344 /* Negate a doubleword integer with doubleword result.
345 Return nonzero if the operation overflows, assuming it's signed.
346 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
347 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
349 int
352 {
354 {
358 }
359 else
360 {
364 }
365 }
366 \f
367 /* Multiply two doubleword integers with doubleword result.
368 Return nonzero if the operation overflows according to UNSIGNED_P.
369 Each argument is given as two `HOST_WIDE_INT' pieces.
370 One argument is L1 and H1; the other, L2 and H2.
371 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
373 int
378 {
393 {
396 {
398 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
400 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
404 }
406 }
411 /* Unsigned overflow is immediate. */
415 /* Check for signed overflow by calculating the signed representation of the
416 top half of the result; it should agree with the low half's sign bit. */
418 {
421 }
423 {
426 }
428 }
429 \f
430 /* Shift the doubleword integer in L1, H1 left by COUNT places
431 keeping only PREC bits of result.
432 Shift right if COUNT is negative.
433 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
434 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
436 void
440 {
444 {
447 }
453 {
454 /* Shifting by the host word size is undefined according to the
455 ANSI standard, so we must handle this as a special case. */
458 }
460 {
463 }
464 else
465 {
469 }
471 /* Sign extend all bits that are beyond the precision. */
479 ;
481 {
484 }
485 else
486 {
490 }
491 }
493 /* Shift the doubleword integer in L1, H1 right by COUNT places
494 keeping only PREC bits of result. COUNT must be positive.
495 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
496 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
498 void
503 {
506 signmask = (arith
514 {
515 /* Shifting by the host word size is undefined according to the
516 ANSI standard, so we must handle this as a special case. */
519 }
521 {
524 }
525 else
526 {
530 }
532 /* Zero / sign extend all bits that are beyond the precision. */
535 {
538 }
540 ;
542 {
545 }
546 else
547 {
551 }
552 }
553 \f
554 /* Rotate the doubleword integer in L1, H1 left by COUNT places
555 keeping only PREC bits of result.
556 Rotate right if COUNT is negative.
557 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
559 void
563 {
575 }
577 /* Rotate the doubleword integer in L1, H1 left by COUNT places
578 keeping only PREC bits of result. COUNT must be positive.
579 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
581 void
585 {
597 }
598 \f
599 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
600 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
601 CODE is a tree code for a kind of division, one of
602 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
603 or EXACT_DIV_EXPR
604 It controls how the quotient is rounded to an integer.
605 Return nonzero if the operation overflows.
606 UNS nonzero says do unsigned division. */
608 int
611 HOST_WIDE_INT hnum_orig,
613 HOST_WIDE_INT hden_orig,
617 {
633 /* Calculate quotient sign and convert operands to unsigned. */
635 {
637 {
639 /* (minimum integer) / (-1) is the only overflow case. */
643 }
645 {
648 }
649 }
654 /* This unsigned division rounds toward zero. */
657 }
661 /* hden != 0 already checked. */
666 }
676 /* Special code for when the divisor < BASE. */
678 {
679 /* hnum != 0 already checked. */
681 {
685 }
686 }
687 else
688 {
689 /* Full double precision division,
690 with thanks to Don Knuth's "Seminumerical Algorithms". */
694 /* Find the highest nonzero divisor digit. */
697 {
700 }
702 /* Insure that the first digit of the divisor is at least BASE/2.
703 This is required by the quotient digit estimation algorithm. */
710 {
714 }
719 {
724 }
725 }
729 /* Main loop */
731 {
732 /* Guess the next quotient digit, quo_est, by dividing the first
733 two remaining dividend digits by the high order quotient digit.
734 quo_est is never low and is at most 2 high. */
741 else
744 /* Refine quo_est so it's usually correct, and at most one high. */
749 quo_est--;
751 /* Try QUO_EST as the quotient digit, by multiplying the
752 divisor by QUO_EST and subtracting from the remaining dividend.
753 Keep in mind that QUO_EST is the I - 1st digit. */
757 {
763 }
765 /* If quo_est was high by one, then num[i] went negative and
766 we need to correct things. */
768 {
769 quo_est--;
772 {
776 }
779 }
781 /* Store the quotient digit. */
783 }
784 }
788 finish_up:
789 /* If result is negative, make it so. */
793 /* Compute trial remainder: rem = num - (quo * den) */
799 {
808 {
809 /* quo = quo - 1; */
812 }
813 else
820 {
823 }
824 else
830 {
836 /* Get absolute values. */
842 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
851 {
853 /* quo = quo - 1; */
856 else
857 /* quo = quo + 1; */
860 }
861 else
863 }
868 }
870 /* Compute true remainder: rem = num - (quo * den) */
875 }
877 /* If ARG2 divides ARG1 with zero remainder, carries out the division
878 of type CODE and returns the quotient.
879 Otherwise returns NULL_TREE. */
881 tree
883 {
890 /* The sign of the division is according to operand two, that
891 does the correct thing for POINTER_PLUS_EXPR where we want
892 a signed division. */
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. */
1136 /* We want to canonicalize to positive real constants. Pretend
1137 that only negative ones can be easily negated. */
1155 /* -(A + B) -> (-B) - A. */
1160 /* -(A + B) -> (-A) - B. */
1164 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1174 /* Fall through. */
1187 /* In general we can't negate A / B, because if A is INT_MIN and
1188 B is 1, we may turn this into INT_MIN / -1 which is undefined
1189 and actually traps on some architectures. But if overflow is
1190 undefined, we can negate, because - (INT_MIN / 1) is an
1191 overflow. */
1199 /* Negate -((double)float) as (double)(-float). */
1201 {
1205 }
1209 /* Negate -f(x) as f(-x). */
1215 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1217 {
1223 }
1228 }
1230 }
1232 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1233 simplification is possible.
1234 If negate_expr_p would return true for T, NULL_TREE will never be
1235 returned. */
1237 static tree
1239 {
1241 tree tem;
1244 {
1245 /* Convert - (~A) to A + 1. */
1261 /* Two's complement FP formats, such as c4x, may overflow. */
1271 {
1280 }
1302 {
1303 /* -(A + B) -> (-B) - A. */
1307 {
1311 }
1313 /* -(A + B) -> (-A) - B. */
1315 {
1319 }
1320 }
1324 /* - (A - B) -> B - A */
1336 /* Fall through. */
1340 {
1349 }
1357 /* In general we can't negate A / B, because if A is INT_MIN and
1358 B is 1, we may turn this into INT_MIN / -1 which is undefined
1359 and actually traps on some architectures. But if overflow is
1360 undefined, we can negate, because - (INT_MIN / 1) is an
1361 overflow. */
1363 {
1368 {
1375 }
1378 {
1385 }
1386 }
1390 /* Convert -((double)float) into (double)(-float). */
1392 {
1396 }
1400 /* Negate -f(x) as f(-x). */
1403 {
1409 }
1413 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1415 {
1420 {
1427 }
1428 }
1433 }
1436 }
1438 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1439 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1440 return NULL_TREE. */
1442 static tree
1444 {
1446 location_t loc;
1457 {
1460 }
1462 }
1463 \f
1464 /* Split a tree IN into a constant, literal and variable parts that could be
1465 combined with CODE to make IN. "constant" means an expression with
1466 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1467 commutative arithmetic operation. Store the constant part into *CONP,
1468 the literal in *LITP and return the variable part. If a part isn't
1469 present, set it to null. If the tree does not decompose in this way,
1470 return the entire tree as the variable part and the other parts as null.
1472 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1473 case, we negate an operand that was subtracted. Except if it is a
1474 literal for which we use *MINUS_LITP instead.
1476 If NEGATE_P is true, we are negating all of IN, again except a literal
1477 for which we use *MINUS_LITP instead.
1479 If IN is itself a literal or constant, return it as appropriate.
1481 Note that we do not guarantee that any of the three values will be the
1482 same type as IN, but they will have the same signedness and mode. */
1484 static tree
1487 {
1494 /* Strip any conversions that don't change the machine mode or signedness. */
1503 /* We can associate addition and subtraction together (even
1504 though the C standard doesn't say so) for integers because
1505 the value is not affected. For reals, the value might be
1506 affected, so we can't. */
1509 {
1515 /* First see if either of the operands is a literal, then a constant. */
1528 /* If we haven't dealt with either operand, this is not a case we can
1529 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1534 else
1537 /* Now do any needed negations. */
1544 }
1547 else
1551 {
1558 }
1561 }
1563 /* Re-associate trees split by the above function. T1 and T2 are
1564 either expressions to associate or null. Return the new
1565 expression, if any. LOC is the location of the new expression. If
1566 we build an operation, do it in TYPE and with CODE. */
1568 static tree
1570 {
1571 tree tem;
1578 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1579 try to fold this since we will have infinite recursion. But do
1580 deal with any NEGATE_EXPRs. */
1583 {
1585 {
1594 }
1596 {
1599 }
1604 }
1608 associate_trees_exit:
1611 }
1612 \f
1613 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1614 for use in int_const_binop, size_binop and size_diffop. */
1616 static bool
1618 {
1625 {
1634 }
1639 }
1642 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1643 to produce a new constant. Return NULL_TREE if we don't know how
1644 to evaluate CODE at compile-time.
1646 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1648 tree
1650 {
1654 HOST_WIDE_INT hi;
1656 HOST_WIDE_INT garbageh;
1657 tree t;
1660 int is_sizetype
1670 {
1686 /* It's unclear from the C standard whether shifts can overflow.
1687 The following code ignores overflow; perhaps a C standard
1688 interpretation ruling is needed. */
1717 /* This is a shortcut for a common special case. */
1722 {
1728 }
1730 /* ... fall through ... */
1736 {
1739 }
1742 {
1745 }
1752 /* This is a shortcut for a common special case. */
1757 {
1762 }
1764 /* ... fall through ... */
1782 else
1788 else
1794 }
1797 {
1800 /* Propagate overflow flags ourselves. */
1803 {
1806 }
1807 }
1808 else
1814 }
1816 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1817 constant. We assume ARG1 and ARG2 have the same data type, or at least
1818 are the same kind of constant and the same machine mode. Return zero if
1819 combining the constants is not allowed in the current operating mode.
1821 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1823 static tree
1825 {
1826 /* Sanity check for the recursive cases. */
1837 {
1839 REAL_VALUE_TYPE d1;
1840 REAL_VALUE_TYPE d2;
1841 REAL_VALUE_TYPE value;
1842 REAL_VALUE_TYPE result;
1846 /* The following codes are handled by real_arithmetic. */
1848 {
1859 }
1867 /* Don't perform operation if we honor signaling NaNs and
1868 either operand is a NaN. */
1873 /* Don't perform operation if it would raise a division
1874 by zero exception. */
1880 /* If either operand is a NaN, just return it. Otherwise, set up
1881 for floating-point trap; we return an overflow. */
1890 /* Don't constant fold this floating point operation if
1891 the result has overflowed and flag_trapping_math. */
1899 /* Don't constant fold this floating point operation if the
1900 result may dependent upon the run-time rounding mode and
1901 flag_rounding_math is set, or if GCC's software emulation
1902 is unable to accurately represent the result. */
1912 }
1915 {
1916 FIXED_VALUE_TYPE f1;
1917 FIXED_VALUE_TYPE f2;
1918 FIXED_VALUE_TYPE result;
1923 /* The following codes are handled by fixed_arithmetic. */
1925 {
1942 }
1949 /* Propagate overflow flags. */
1953 }
1956 {
1965 {
1976 mpc_mul);
1981 notrunc);
1985 notrunc);
1992 mpc_div);
1993 /* Fallthru ... */
1999 {
2000 /* Keep this algorithm in sync with
2001 tree-complex.c:expand_complex_div_straight().
2003 Expand complex division to scalars, straightforward algorithm.
2004 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
2005 t = br*br + bi*bi
2006 */
2007 tree magsquared
2011 notrunc);
2012 tree t1
2016 notrunc);
2017 tree t2
2021 notrunc);
2025 }
2026 else
2027 {
2028 /* Keep this algorithm in sync with
2029 tree-complex.c:expand_complex_div_wide().
2031 Expand complex division to scalars, modified algorithm to minimize
2032 overflow with wide input ranges. */
2038 {
2039 /* In the TRUE branch, we compute
2040 ratio = br/bi;
2041 div = (br * ratio) + bi;
2042 tr = (ar * ratio) + ai;
2043 ti = (ai * ratio) - ar;
2044 tr = tr / div;
2045 ti = ti / div; */
2049 notrunc),
2050 notrunc);
2058 }
2059 else
2060 {
2061 /* In the FALSE branch, we compute
2062 ratio = d/c;
2063 divisor = (d * ratio) + c;
2064 tr = (b * ratio) + a;
2065 ti = b - (a * ratio);
2066 tr = tr / div;
2067 ti = ti / div; */
2071 notrunc),
2072 notrunc);
2081 }
2082 }
2087 }
2091 }
2094 {
2106 {
2109 /* The trailing elements can be empty and should be treated as 0 */
2112 else
2113 {
2116 }
2120 else
2121 {
2124 }
2128 /* It is possible that const_binop cannot handle the given
2129 code and return NULL_TREE */
2134 }
2136 }
2138 }
2140 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2141 indicates which particular sizetype to create. */
2143 tree
2145 {
2147 }
2148 \f
2149 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2150 is a tree code. The type of the result is taken from the operands.
2151 Both must be equivalent integer types, ala int_binop_types_match_p.
2152 If the operands are constant, so is the result. */
2154 tree
2156 {
2165 /* Handle the special case of two integer constants faster. */
2167 {
2168 /* And some specific cases even faster than that. */
2170 {
2175 }
2177 {
2180 }
2182 {
2185 }
2187 /* Handle general case of two integer constants. */
2189 }
2192 }
2194 /* Given two values, either both of sizetype or both of bitsizetype,
2195 compute the difference between the two values. Return the value
2196 in signed type corresponding to the type of the operands. */
2198 tree
2200 {
2202 tree ctype;
2207 /* If the type is already signed, just do the simple thing. */
2215 else
2218 /* If either operand is not a constant, do the conversions to the signed
2219 type and subtract. The hardware will do the right thing with any
2220 overflow in the subtraction. */
2226 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2227 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2228 overflow) and negate (which can't either). Special-case a result
2229 of zero while we're here. */
2235 else
2239 MINUS_EXPR,
2241 }
2242 \f
2243 /* A subroutine of fold_convert_const handling conversions of an
2244 INTEGER_CST to another integer type. */
2246 static tree
2248 {
2249 tree t;
2251 /* Given an integer constant, make new constant with new type,
2252 appropriately sign-extended or truncated. */
2255 /* Don't set the overflow when
2256 converting from a pointer, */
2258 /* or to a sizetype with same signedness
2259 and the precision is unchanged.
2260 ??? sizetype is always sign-extended,
2261 but its signedness depends on the
2262 frontend. Thus we see spurious overflows
2263 here if we do not check this. */
2278 }
2280 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2281 to an integer type. */
2283 static tree
2285 {
2287 tree t;
2289 /* The following code implements the floating point to integer
2290 conversion rules required by the Java Language Specification,
2291 that IEEE NaNs are mapped to zero and values that overflow
2292 the target precision saturate, i.e. values greater than
2293 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2294 are mapped to INT_MIN. These semantics are allowed by the
2295 C and C++ standards that simply state that the behavior of
2296 FP-to-integer conversion is unspecified upon overflow. */
2299 REAL_VALUE_TYPE r;
2303 {
2310 }
2312 /* If R is NaN, return zero and show we have an overflow. */
2314 {
2318 }
2320 /* See if R is less than the lower bound or greater than the
2321 upper bound. */
2324 {
2328 {
2332 }
2333 }
2336 {
2339 {
2342 {
2346 }
2347 }
2348 }
2356 }
2358 /* A subroutine of fold_convert_const handling conversions of a
2359 FIXED_CST to an integer type. */
2361 static tree
2363 {
2364 tree t;
2368 /* Right shift FIXED_CST to temp by fbit. */
2372 {
2377 /* Left shift temp to temp_trunc by fbit. */
2382 }
2383 else
2384 {
2389 }
2391 /* If FIXED_CST is negative, we need to round the value toward 0.
2392 By checking if the fractional bits are not zero to add 1 to temp. */
2395 {
2396 double_int one;
2400 }
2402 /* Given a fixed-point constant, make new constant with new type,
2403 appropriately sign-extended or truncated. */
2411 }
2413 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2414 to another floating point type. */
2416 static tree
2418 {
2419 REAL_VALUE_TYPE value;
2420 tree t;
2425 /* If converting an infinity or NAN to a representation that doesn't
2426 have one, set the overflow bit so that we can produce some kind of
2427 error message at the appropriate point if necessary. It's not the
2428 most user-friendly message, but it's better than nothing. */
2435 /* Regular overflow, conversion produced an infinity in a mode that
2436 can't represent them. */
2441 else
2444 }
2446 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2447 to a floating point type. */
2449 static tree
2451 {
2452 REAL_VALUE_TYPE value;
2453 tree t;
2460 }
2462 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2463 to another fixed-point type. */
2465 static tree
2467 {
2468 FIXED_VALUE_TYPE value;
2469 tree t;
2476 /* Propagate overflow flags. */
2480 }
2482 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2483 to a fixed-point type. */
2485 static tree
2487 {
2488 FIXED_VALUE_TYPE value;
2489 tree t;
2498 /* Propagate overflow flags. */
2502 }
2504 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2505 to a fixed-point type. */
2507 static tree
2509 {
2510 FIXED_VALUE_TYPE value;
2511 tree t;
2519 /* Propagate overflow flags. */
2523 }
2525 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2526 type TYPE. If no simplification can be done return NULL_TREE. */
2528 static tree
2530 {
2536 {
2543 }
2545 {
2552 }
2554 {
2561 }
2563 }
2565 /* Construct a vector of zero elements of vector type TYPE. */
2567 static tree
2569 {
2580 }
2582 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2584 bool
2586 {
2601 {
2620 }
2621 }
2623 /* Convert expression ARG to type TYPE. Used by the middle-end for
2624 simple conversions in preference to calling the front-end's convert. */
2626 tree
2628 {
2630 tree tem;
2644 {
2647 /* Handle conversions between pointers to different address spaces. */
2652 /* fall through */
2657 {
2661 }
2675 {
2679 }
2681 {
2685 }
2687 {
2691 }
2694 {
2712 }
2717 {
2721 }
2724 {
2738 }
2742 {
2751 integer_zero_node));
2753 {
2757 {
2763 }
2771 }
2775 }
2793 }
2794 fold_convert_exit:
2797 }
2798 \f
2799 /* Return false if expr can be assumed not to be an lvalue, true
2800 otherwise. */
2802 static bool
2804 {
2805 /* We only need to wrap lvalue tree codes. */
2807 {
2839 /* Assume the worst for front-end tree codes. */
2843 }
2846 }
2848 /* Return an expr equal to X but certainly not valid as an lvalue. */
2850 tree
2852 {
2853 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2854 us. */
2863 }
2865 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2866 Zero means allow extended lvalues. */
2870 /* When pedantic, return an expr equal to X but certainly not valid as a
2871 pedantic lvalue. Otherwise, return X. */
2873 static tree
2875 {
2880 }
2881 \f
2882 /* Given a tree comparison code, return the code that is the logical inverse
2883 of the given code. It is not safe to do this for floating-point
2884 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2885 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2887 enum tree_code
2889 {
2894 {
2925 }
2926 }
2928 /* Similar, but return the comparison that results if the operands are
2929 swapped. This is safe for floating-point. */
2931 enum tree_code
2933 {
2935 {
2961 }
2962 }
2965 /* Convert a comparison tree code from an enum tree_code representation
2966 into a compcode bit-based encoding. This function is the inverse of
2967 compcode_to_comparison. */
2969 static enum comparison_code
2971 {
2973 {
3004 }
3005 }
3007 /* Convert a compcode bit-based encoding of a comparison operator back
3008 to GCC's enum tree_code representation. This function is the
3009 inverse of comparison_to_compcode. */
3011 static enum tree_code
3013 {
3015 {
3046 }
3047 }
3049 /* Return a tree for the comparison which is the combination of
3050 doing the AND or OR (depending on CODE) of the two operations LCODE
3051 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
3052 the possibility of trapping if the mode has NaNs, and return NULL_TREE
3053 if this makes the transformation invalid. */
3055 tree
3060 {
3067 {
3078 }
3081 {
3082 /* Eliminate unordered comparisons, as well as LTGT and ORD
3083 which are not used unless the mode has NaNs. */
3089 }
3091 {
3092 /* Check that the original operation and the optimized ones will trap
3093 under the same condition. */
3104 /* In a short-circuited boolean expression the LHS might be
3105 such that the RHS, if evaluated, will never trap. For
3106 example, in ORD (x, y) && (x < y), we evaluate the RHS only
3107 if neither x nor y is NaN. (This is a mixed blessing: for
3108 example, the expression above will never trap, hence
3109 optimizing it to x < y would be invalid). */
3114 /* If the comparison was short-circuited, and only the RHS
3115 trapped, we may now generate a spurious trap. */
3120 /* If we changed the conditions that cause a trap, we lose. */
3123 }
3129 else
3130 {
3135 }
3136 }
3137 \f
3138 /* Return nonzero if two operands (typically of the same tree node)
3139 are necessarily equal. If either argument has side-effects this
3140 function returns zero. FLAGS modifies behavior as follows:
3142 If OEP_ONLY_CONST is set, only return nonzero for constants.
3143 This function tests whether the operands are indistinguishable;
3144 it does not test whether they are equal using C's == operation.
3145 The distinction is important for IEEE floating point, because
3146 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3147 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3149 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3150 even though it may hold multiple values during a function.
3151 This is because a GCC tree node guarantees that nothing else is
3152 executed between the evaluation of its "operands" (which may often
3153 be evaluated in arbitrary order). Hence if the operands themselves
3154 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3155 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3156 unset means assuming isochronic (or instantaneous) tree equivalence.
3157 Unless comparing arbitrary expression trees, such as from different
3158 statements, this flag can usually be left unset.
3160 If OEP_PURE_SAME is set, then pure functions with identical arguments
3161 are considered the same. It is used when the caller has other ways
3162 to ensure that global memory is unchanged in between. */
3164 int
3166 {
3167 /* If either is ERROR_MARK, they aren't equal. */
3173 /* Check equality of integer constants before bailing out due to
3174 precision differences. */
3178 /* If both types don't have the same signedness, then we can't consider
3179 them equal. We must check this before the STRIP_NOPS calls
3180 because they may change the signedness of the arguments. As pointers
3181 strictly don't have a signedness, require either two pointers or
3182 two non-pointers as well. */
3187 /* We cannot consider pointers to different address space equal. */
3193 /* If both types don't have the same precision, then it is not safe
3194 to strip NOPs. */
3201 /* In case both args are comparisons but with different comparison
3202 code, try to swap the comparison operands of one arg to produce
3203 a match and compare that variant. */
3207 {
3215 }
3218 /* This is needed for conversions and for COMPONENT_REF.
3219 Might as well play it safe and always test this. */
3225 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3226 We don't care about side effects in that case because the SAVE_EXPR
3227 takes care of that for us. In all other cases, two expressions are
3228 equal if they have no side effects. If we have two identical
3229 expressions with side effects that should be treated the same due
3230 to the only side effects being identical SAVE_EXPR's, that will
3231 be detected in the recursive calls below. */
3237 /* Next handle constant cases, those for which we can return 1 even
3238 if ONLY_CONST is set. */
3241 {
3256 {
3257 /* If we do not distinguish between signed and unsigned zero,
3258 consider them equal. */
3261 }
3265 {
3271 {
3273 flags))
3277 }
3280 }
3284 flags)
3286 flags));
3299 }
3304 /* Define macros to test an operand from arg0 and arg1 for equality and a
3305 variant that allows null and views null as being different from any
3306 non-null value. In the latter case, if either is null, the both
3307 must be; otherwise, do the normal comparison. */
3308 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3309 TREE_OPERAND (arg1, N), flags)
3311 #define OP_SAME_WITH_NULL(N) \
3312 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3313 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3316 {
3318 /* Two conversions are equal only if signedness and modes match. */
3320 {
3321 CASE_CONVERT:
3329 }
3339 /* For commutative ops, allow the other order. */
3347 /* If either of the pointer (or reference) expressions we are
3348 dereferencing contain a side effect, these cannot be equal. */
3354 {
3364 /* Operands 2 and 3 may be null.
3365 Compare the array index by value if it is constant first as we
3366 may have different types but same value here. */
3375 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3376 may be NULL when we're called to compare MEM_EXPRs. */
3386 }
3390 {
3405 /* Otherwise take into account this is a commutative operation. */
3416 }
3420 {
3422 /* If the CALL_EXPRs call different functions, then they
3423 clearly can not be equal. */
3425 flags))
3428 {
3432 else
3436 }
3438 /* Now see if all the arguments are the same. */
3439 {
3450 /* If we get here and both argument lists are exhausted
3451 then the CALL_EXPRs are equal. */
3453 }
3456 }
3459 /* Consider __builtin_sqrt equal to sqrt. */
3467 }
3469 #undef OP_SAME
3470 #undef OP_SAME_WITH_NULL
3471 }
3472 \f
3473 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3474 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3476 When in doubt, return 0. */
3478 static int
3480 {
3492 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3493 and see if the inner values are the same. This removes any
3494 signedness comparison, which doesn't matter here. */
3501 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3502 actual comparison operand, ARG0.
3504 First throw away any conversions to wider types
3505 already present in the operands. */
3514 {
3517 /* Make sure shorter operand is extended the right way
3518 to match the longer operand. */
3524 }
3527 }
3528 \f
3529 /* See if ARG is an expression that is either a comparison or is performing
3530 arithmetic on comparisons. The comparisons must only be comparing
3531 two different values, which will be stored in *CVAL1 and *CVAL2; if
3532 they are nonzero it means that some operands have already been found.
3533 No variables may be used anywhere else in the expression except in the
3534 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3535 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3537 If this is true, return 1. Otherwise, return zero. */
3539 static int
3541 {
3545 /* We can handle some of the tcc_expression cases here. */
3555 {
3556 /* If we've already found a CVAL1 or CVAL2, this expression is
3557 two complex to handle. */
3563 }
3566 {
3589 /* First see if we can handle the first operand, then the second. For
3590 the second operand, we know *CVAL1 can't be zero. It must be that
3591 one side of the comparison is each of the values; test for the
3592 case where this isn't true by failing if the two operands
3593 are the same. */
3602 ;
3606 ;
3607 else
3611 ;
3615 ;
3616 else
3623 }
3624 }
3625 \f
3626 /* ARG is a tree that is known to contain just arithmetic operations and
3627 comparisons. Evaluate the operations in the tree substituting NEW0 for
3628 any occurrence of OLD0 as an operand of a comparison and likewise for
3629 NEW1 and OLD1. */
3631 static tree
3634 {
3639 /* We can handle some of the tcc_expression cases here. */
3647 {
3662 {
3681 }
3682 /* Fall through - ??? */
3685 {
3689 /* We need to check both for exact equality and tree equality. The
3690 former will be true if the operand has a side-effect. In that
3691 case, we know the operand occurred exactly once. */
3704 }
3708 }
3709 }
3710 \f
3711 /* Return a tree for the case when the result of an expression is RESULT
3712 converted to TYPE and OMITTED was previously an operand of the expression
3713 but is now not needed (e.g., we folded OMITTED * 0).
3715 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3716 the conversion of RESULT to TYPE. */
3718 tree
3720 {
3723 /* If the resulting operand is an empty statement, just return the omitted
3724 statement casted to void. */
3726 {
3729 }
3732 {
3735 }
3739 omit_one_operand_exit:
3742 }
3744 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3746 static tree
3748 tree omitted)
3749 {
3752 /* If the resulting operand is an empty statement, just return the omitted
3753 statement casted to void. */
3755 {
3758 }
3761 {
3764 }
3768 pedantic_omit_one_operand_exit:
3771 }
3773 /* Return a tree for the case when the result of an expression is RESULT
3774 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3775 of the expression but are now not needed.
3777 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3778 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3779 evaluated before OMITTED2. Otherwise, if neither has side effects,
3780 just do the conversion of RESULT to TYPE. */
3782 tree
3785 {
3789 {
3792 }
3794 {
3797 }
3800 }
3802 \f
3803 /* Return a simplified tree node for the truth-negation of ARG. This
3804 never alters ARG itself. We assume that ARG is an operation that
3805 returns a truth value (0 or 1).
3807 FIXME: one would think we would fold the result, but it causes
3808 problems with the dominator optimizer. */
3810 tree
3812 {
3817 /* If this is a comparison, we can simply invert it, except for
3818 floating-point non-equality comparisons, in which case we just
3819 enclose a TRUTH_NOT_EXPR around what we have. */
3822 {
3825 && flag_trapping_math
3837 }
3840 {
3869 /* Here we can invert either operand. We invert the first operand
3870 unless the second operand is a TRUTH_NOT_EXPR in which case our
3871 result is the XOR of the first operand with the inside of the
3872 negation of the second operand. */
3877 else
3911 {
3922 /* A COND_EXPR may have a throw as one operand, which
3923 then has void type. Just leave void operands
3924 as they are. */
3931 }
3948 CASE_CONVERT:
3950 {
3953 }
3955 /* ... fall through ... */
3986 }
3992 }
3994 /* Return a simplified tree node for the truth-negation of ARG. This
3995 never alters ARG itself. We assume that ARG is an operation that
3996 returns a truth value (0 or 1).
3998 FIXME: one would think we would fold the result, but it causes
3999 problems with the dominator optimizer. */
4001 tree
4003 {
4004 tree tem;
4011 {
4014 }
4017 }
4019 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
4020 operands are another bit-wise operation with a common input. If so,
4021 distribute the bit operations to save an operation and possibly two if
4022 constants are involved. For example, convert
4023 (A | B) & (A | C) into A | (B & C)
4024 Further simplification will occur if B and C are constants.
4026 If this optimization cannot be done, 0 will be returned. */
4028 static tree
4031 {
4032 tree common;
4042 {
4046 }
4048 {
4052 }
4054 {
4058 }
4060 {
4064 }
4065 else
4073 }
4075 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
4076 with code CODE. This optimization is unsafe. */
4077 static tree
4080 {
4084 /* (A / C) +- (B / C) -> (A +- B) / C. */
4094 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
4099 {
4111 }
4114 }
4115 \f
4116 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4117 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
4119 static tree
4122 {
4126 {
4133 }
4148 }
4150 /* Optimize a bit-field compare.
4152 There are two cases: First is a compare against a constant and the
4153 second is a comparison of two items where the fields are at the same
4154 bit position relative to the start of a chunk (byte, halfword, word)
4155 large enough to contain it. In these cases we can avoid the shift
4156 implicit in bitfield extractions.
4158 For constants, we emit a compare of the shifted constant with the
4159 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4160 compared. For two fields at the same position, we do the ANDs with the
4161 similar mask and compare the result of the ANDs.
4163 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4164 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4165 are the left and right operands of the comparison, respectively.
4167 If the optimization described above can be done, we return the resulting
4168 tree. Otherwise we return zero. */
4170 static tree
4173 {
4182 tree mask;
4183 tree offset;
4185 /* Get all the information about the extractions being done. If the bit size
4186 if the same as the size of the underlying object, we aren't doing an
4187 extraction at all and so can do nothing. We also don't want to
4188 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4189 then will no longer be able to replace it. */
4197 {
4198 /* If this is not a constant, we can only do something if bit positions,
4199 sizes, and signedness are the same. */
4207 }
4209 /* See if we can find a mode to refer to this field. We should be able to,
4210 but fail if we can't. */
4219 /* Set signed and unsigned types of the precision of this mode for the
4220 shifts below. */
4224 /* Compute the bit position and size for the new reference and our offset
4225 within it. If the new reference is the same size as the original, we
4226 won't optimize anything, so return zero. */
4236 /* Make the mask to be used against the extracted field. */
4243 /* If not comparing with constant, just rework the comparison
4244 and return. */
4248 unsigned_type,
4251 mask),
4254 unsigned_type,
4257 mask));
4259 /* Otherwise, we are handling the constant case. See if the constant is too
4260 big for the field. Warn and return a tree of for 0 (false) if so. We do
4261 this not only for its own sake, but to avoid having to test for this
4262 error case below. If we didn't, we might generate wrong code.
4264 For unsigned fields, the constant shifted right by the field length should
4265 be all zero. For signed fields, the high-order bits should agree with
4266 the sign bit. */
4269 {
4274 {
4278 }
4279 }
4280 else
4281 {
4286 {
4290 }
4291 }
4293 /* Single-bit compares should always be against zero. */
4295 {
4298 }
4300 /* Make a new bitfield reference, shift the constant over the
4301 appropriate number of bits and mask it with the computed mask
4302 (in case this was a signed field). If we changed it, make a new one. */
4305 {
4308 }
4318 rhs);
4321 }
4322 \f
4323 /* Subroutine for fold_truthop: decode a field reference.
4325 If EXP is a comparison reference, we return the innermost reference.
4327 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4328 set to the starting bit number.
4330 If the innermost field can be completely contained in a mode-sized
4331 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4333 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4334 otherwise it is not changed.
4336 *PUNSIGNEDP is set to the signedness of the field.
4338 *PMASK is set to the mask used. This is either contained in a
4339 BIT_AND_EXPR or derived from the width of the field.
4341 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4343 Return 0 if this is not a component reference or is one that we can't
4344 do anything with. */
4346 static tree
4351 {
4355 tree unsigned_type;
4358 /* All the optimizations using this function assume integer fields.
4359 There are problems with FP fields since the type_for_size call
4360 below can fail for, e.g., XFmode. */
4364 /* We are interested in the bare arrangement of bits, so strip everything
4365 that doesn't affect the machine mode. However, record the type of the
4366 outermost expression if it may matter below. */
4373 {
4379 }
4388 /* If the number of bits in the reference is the same as the bitsize of
4389 the outer type, then the outer type gives the signedness. Otherwise
4390 (in case of a small bitfield) the signedness is unchanged. */
4394 /* Compute the mask to access the bitfield. */
4403 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4411 }
4413 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4414 bit positions. */
4416 static int
4418 {
4421 tree tmask;
4425 return
4432 }
4434 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4435 represents the sign bit of EXP's type. If EXP represents a sign
4436 or zero extension, also test VAL against the unextended type.
4437 The return value is the (sub)expression whose sign bit is VAL,
4438 or NULL_TREE otherwise. */
4440 static tree
4442 {
4446 tree t;
4448 /* Tree EXP must have an integral type. */
4453 /* Tree VAL must be an integer constant. */
4460 {
4467 }
4468 else
4469 {
4476 }
4478 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4479 treat VAL as if it were unsigned. */
4484 /* Handle extension from a narrower type. */
4490 }
4492 /* Subroutine for fold_truthop: determine if an operand is simple enough
4493 to be evaluated unconditionally. */
4495 static int
4497 {
4498 /* Strip any conversions that don't change the machine mode. */
4507 /* Don't regard global variables as simple. They may be
4508 allocated in ways unknown to the compiler (shared memory,
4509 #pragma weak, etc). */
4512 /* Loading a static variable is unduly expensive, but global
4513 registers aren't expensive. */
4515 }
4516 \f
4517 /* The following functions are subroutines to fold_range_test and allow it to
4518 try to change a logical combination of comparisons into a range test.
4520 For example, both
4521 X == 2 || X == 3 || X == 4 || X == 5
4522 and
4523 X >= 2 && X <= 5
4524 are converted to
4525 (unsigned) (X - 2) <= 3
4527 We describe each set of comparisons as being either inside or outside
4528 a range, using a variable named like IN_P, and then describe the
4529 range with a lower and upper bound. If one of the bounds is omitted,
4530 it represents either the highest or lowest value of the type.
4532 In the comments below, we represent a range by two numbers in brackets
4533 preceded by a "+" to designate being inside that range, or a "-" to
4534 designate being outside that range, so the condition can be inverted by
4535 flipping the prefix. An omitted bound is represented by a "-". For
4536 example, "- [-, 10]" means being outside the range starting at the lowest
4537 possible value and ending at 10, in other words, being greater than 10.
4538 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4539 always false.
4541 We set up things so that the missing bounds are handled in a consistent
4542 manner so neither a missing bound nor "true" and "false" need to be
4543 handled using a special case. */
4545 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4546 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4547 and UPPER1_P are nonzero if the respective argument is an upper bound
4548 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4549 must be specified for a comparison. ARG1 will be converted to ARG0's
4550 type if both are specified. */
4552 static tree
4555 {
4556 tree tem;
4560 /* If neither arg represents infinity, do the normal operation.
4561 Else, if not a comparison, return infinity. Else handle the special
4562 comparison rules. Note that most of the cases below won't occur, but
4563 are handled for consistency. */
4566 {
4571 }
4576 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4577 for neither. In real maths, we cannot assume open ended ranges are
4578 the same. But, this is computer arithmetic, where numbers are finite.
4579 We can therefore make the transformation of any unbounded range with
4580 the value Z, Z being greater than any representable number. This permits
4581 us to treat unbounded ranges as equal. */
4585 {
4606 }
4609 }
4610 \f
4611 /* Given EXP, a logical expression, set the range it is testing into
4612 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4613 actually being tested. *PLOW and *PHIGH will be made of the same
4614 type as the returned expression. If EXP is not a comparison, we
4615 will most likely not be returning a useful value and range. Set
4616 *STRICT_OVERFLOW_P to true if the return value is only valid
4617 because signed overflow is undefined; otherwise, do not change
4618 *STRICT_OVERFLOW_P. */
4620 tree
4623 {
4631 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4632 and see if we can refine the range. Some of the cases below may not
4633 happen, but it doesn't seem worth worrying about this. We "continue"
4634 the outer loop when we've changed something; otherwise we "break"
4635 the switch, which will "break" the while. */
4641 {
4646 {
4658 }
4661 {
4668 /* We can only do something if the range is testing for zero
4669 and if the second operand is an integer constant. Note that
4670 saying something is "in" the range we make is done by
4671 complementing IN_P since it will set in the initial case of
4672 being not equal to zero; "out" is leaving it alone. */
4679 {
4700 }
4702 /* If this is an unsigned comparison, we also know that EXP is
4703 greater than or equal to zero. We base the range tests we make
4704 on that fact, so we record it here so we can parse existing
4705 range tests. We test arg0_type since often the return type
4706 of, e.g. EQ_EXPR, is boolean. */
4708 {
4712 NULL_TREE))
4717 /* If the high bound is missing, but we have a nonzero low
4718 bound, reverse the range so it goes from zero to the low bound
4719 minus 1. */
4721 {
4726 }
4727 }
4733 /* (-x) IN [a,b] -> x in [-b, -a] */
4745 /* ~ X -> -X - 1 */
4755 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4756 move a constant to the other side. */
4761 /* If EXP is signed, any overflow in the computation is undefined,
4762 so we don't worry about it so long as our computations on
4763 the bounds don't overflow. For unsigned, overflow is defined
4764 and this is exactly the right thing. */
4776 /* Check for an unsigned range which has wrapped around the maximum
4777 value thus making n_high < n_low, and normalize it. */
4779 {
4785 /* If the range is of the form +/- [ x+1, x ], we won't
4786 be able to normalize it. But then, it represents the
4787 whole range or the empty set, so make it
4788 +/- [ -, - ]. */
4792 else
4794 }
4795 else
4819 /* If we're converting arg0 from an unsigned type, to exp,
4820 a signed type, we will be doing the comparison as unsigned.
4821 The tests above have already verified that LOW and HIGH
4822 are both positive.
4824 So we have to ensure that we will handle large unsigned
4825 values the same way that the current signed bounds treat
4826 negative values. */
4829 {
4830 tree high_positive;
4831 tree equiv_type;
4832 /* For fixed-point modes, we need to pass the saturating flag
4833 as the 2nd parameter. */
4838 else
4842 /* A range without an upper bound is, naturally, unbounded.
4843 Since convert would have cropped a very large value, use
4844 the max value for the destination type. */
4845 high_positive
4852 high_positive),
4855 /* If the low bound is specified, "and" the range with the
4856 range for which the original unsigned value will be
4857 positive. */
4859 {
4863 integer_zero_node),
4864 high_positive))
4868 }
4869 else
4870 {
4871 /* Otherwise, "or" the range with the range of the input
4872 that will be interpreted as negative. */
4876 integer_zero_node),
4877 high_positive))
4881 }
4882 }
4890 }
4893 }
4895 /* If EXP is a constant, we can evaluate whether this is true or false. */
4897 {
4904 }
4908 }
4909 \f
4910 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4911 type, TYPE, return an expression to test if EXP is in (or out of, depending
4912 on IN_P) the range. Return 0 if the test couldn't be created. */
4914 tree
4917 {
4920 #ifdef HAVE_canonicalize_funcptr_for_compare
4921 /* Disable this optimization for function pointer expressions
4922 on targets that require function pointer canonicalization. */
4927 #endif
4930 {
4936 }
4954 {
4956 {
4960 }
4962 }
4964 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4966 {
4968 HOST_WIDE_INT hi;
4973 {
4976 }
4977 else
4978 {
4981 }
4984 {
4986 {
4989 etype
4991 else
4994 }
4997 }
4998 }
5000 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5001 This requires wrap-around arithmetics for the type of the expression.
5002 First make sure that arithmetics in this type is valid, then make sure
5003 that it wraps around. */
5009 {
5012 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5013 for the type in question, as we rely on this here. */
5023 else
5025 }
5035 {
5037 {
5044 }
5046 }
5054 }
5055 \f
5056 /* Return the predecessor of VAL in its type, handling the infinite case. */
5058 static tree
5060 {
5066 else
5068 }
5070 /* Return the successor of VAL in its type, handling the infinite case. */
5072 static tree
5074 {
5080 else
5082 }
5084 /* Given two ranges, see if we can merge them into one. Return 1 if we
5085 can, 0 if we can't. Set the output range into the specified parameters. */
5087 bool
5090 {
5094 tree tem;
5104 /* Make range 0 be the range that starts first, or ends last if they
5105 start at the same value. Swap them if it isn't. */
5108 || (lowequal
5111 {
5115 }
5117 /* Now flag two cases, whether the ranges are disjoint or whether the
5118 second range is totally subsumed in the first. Note that the tests
5119 below are simplified by the ones above. */
5125 /* We now have four cases, depending on whether we are including or
5126 excluding the two ranges. */
5128 {
5129 /* If they don't overlap, the result is false. If the second range
5130 is a subset it is the result. Otherwise, the range is from the start
5131 of the second to the end of the first. */
5136 else
5138 }
5141 {
5142 /* If they don't overlap, the result is the first range. If they are
5143 equal, the result is false. If the second range is a subset of the
5144 first, and the ranges begin at the same place, we go from just after
5145 the end of the second range to the end of the first. If the second
5146 range is not a subset of the first, or if it is a subset and both
5147 ranges end at the same place, the range starts at the start of the
5148 first range and ends just before the second range.
5149 Otherwise, we can't describe this as a single range. */
5155 {
5160 {
5161 /* We are in the weird situation where high0 > high1 but
5162 high1 has no successor. Punt. */
5164 }
5165 }
5167 {
5172 {
5173 /* low0 < low1 but low1 has no predecessor. Punt. */
5175 }
5176 }
5177 else
5179 }
5182 {
5183 /* If they don't overlap, the result is the second range. If the second
5184 is a subset of the first, the result is false. Otherwise,
5185 the range starts just after the first range and ends at the
5186 end of the second. */
5191 else
5192 {
5197 {
5198 /* high1 > high0 but high0 has no successor. Punt. */
5200 }
5201 }
5202 }
5204 else
5205 {
5206 /* The case where we are excluding both ranges. Here the complex case
5207 is if they don't overlap. In that case, the only time we have a
5208 range is if they are adjacent. If the second is a subset of the
5209 first, the result is the first. Otherwise, the range to exclude
5210 starts at the beginning of the first range and ends at the end of the
5211 second. */
5213 {
5218 else
5219 {
5220 /* Canonicalize - [min, x] into - [-, x]. */
5223 {
5228 /* FALLTHROUGH */
5241 }
5243 /* Canonicalize - [x, max] into - [x, -]. */
5246 {
5251 /* FALLTHROUGH */
5266 }
5268 /* The ranges might be also adjacent between the maximum and
5269 minimum values of the given type. For
5270 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5271 return + [x + 1, y - 1]. */
5273 {
5280 }
5281 else
5283 }
5284 }
5287 else
5289 }
5293 }
5294 \f
5296 /* Subroutine of fold, looking inside expressions of the form
5297 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5298 of the COND_EXPR. This function is being used also to optimize
5299 A op B ? C : A, by reversing the comparison first.
5301 Return a folded expression whose code is not a COND_EXPR
5302 anymore, or NULL_TREE if no folding opportunity is found. */
5304 static tree
5307 {
5312 tree tem;
5317 /* If we have A op 0 ? A : -A, consider applying the following
5318 transformations:
5320 A == 0? A : -A same as -A
5321 A != 0? A : -A same as 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)
5325 A < 0? A : -A same as -abs (A)
5327 None of these transformations work for modes with signed
5328 zeros. If A is +/-0, the first two transformations will
5329 change the sign of the result (from +0 to -0, or vice
5330 versa). The last four will fix the sign of the result,
5331 even though the original expressions could be positive or
5332 negative, depending on the sign of A.
5334 Note that all these transformations are correct if A is
5335 NaN, since the two alternatives (A and -A) are also NaNs. */
5342 /* In the case that A is of the form X-Y, '-A' (arg2) may
5343 have already been folded to Y-X, check for that. */
5351 {
5365 /* Fall through. */
5387 }
5389 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5390 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5391 both transformations are correct when A is NaN: A != 0
5392 is then true, and A == 0 is false. */
5396 {
5401 }
5403 /* Try some transformations of A op B ? A : B.
5405 A == B? A : B same as B
5406 A != B? A : B same as A
5407 A >= B? A : B same as max (A, B)
5408 A > B? A : B same as max (B, A)
5409 A <= B? A : B same as min (A, B)
5410 A < B? A : B same as min (B, A)
5412 As above, these transformations don't work in the presence
5413 of signed zeros. For example, if A and B are zeros of
5414 opposite sign, the first two transformations will change
5415 the sign of the result. In the last four, the original
5416 expressions give different results for (A=+0, B=-0) and
5417 (A=-0, B=+0), but the transformed expressions do not.
5419 The first two transformations are correct if either A or B
5420 is a NaN. In the first transformation, the condition will
5421 be false, and B will indeed be chosen. In the case of the
5422 second transformation, the condition A != B will be true,
5423 and A will be chosen.
5425 The conversions to max() and min() are not correct if B is
5426 a number and A is not. The conditions in the original
5427 expressions will be false, so all four give B. The min()
5428 and max() versions would give a NaN instead. */
5431 /* Avoid these transformations if the COND_EXPR may be used
5432 as an lvalue in the C++ front-end. PR c++/19199. */
5433 && (in_gimple_form
5438 {
5443 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5445 {
5449 }
5452 {
5461 /* In C++ a ?: expression can be an lvalue, so put the
5462 operand which will be used if they are equal first
5463 so that we can convert this back to the
5464 corresponding COND_EXPR. */
5466 {
5475 }
5482 {
5491 }
5506 }
5507 }
5509 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5510 we might still be able to simplify this. For example,
5511 if C1 is one less or one more than C2, this might have started
5512 out as a MIN or MAX and been transformed by this function.
5513 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5519 {
5523 /* We can replace A with C1 in this case. */
5528 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5529 MIN_EXPR, to preserve the signedness of the comparison. */
5531 OEP_ONLY_CONST)
5535 OEP_ONLY_CONST))
5536 {
5539 arg2));
5542 }
5546 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5547 as above. */
5549 OEP_ONLY_CONST)
5553 OEP_ONLY_CONST))
5554 {
5557 arg2));
5560 }
5564 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5565 MAX_EXPR, to preserve the signedness of the comparison. */
5567 OEP_ONLY_CONST)
5571 OEP_ONLY_CONST))
5572 {
5575 arg2));
5577 }
5581 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5583 OEP_ONLY_CONST)
5587 OEP_ONLY_CONST))
5588 {
5591 arg2));
5593 }
5599 }
5602 }
5605 \f
5606 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5607 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5608 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5609 false) >= 2)
5610 #endif
5612 /* EXP is some logical combination of boolean tests. See if we can
5613 merge it into some range test. Return the new tree if so. */
5615 static tree
5618 {
5626 tree tem;
5630 /* If this is an OR operation, invert both sides; we will invert
5631 again at the end. */
5635 /* If both expressions are the same, if we can merge the ranges, and we
5636 can build the range test, return it or it inverted. If one of the
5637 ranges is always true or always false, consider it to be the same
5638 expression as the other. */
5646 {
5650 }
5652 /* On machines where the branch cost is expensive, if this is a
5653 short-circuited branch and the underlying object on both sides
5654 is the same, make a non-short-circuit operation. */
5660 {
5661 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5662 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5663 which cases we can't do this. */
5665 {
5671 }
5675 {
5684 {
5687 WARN_STRICT_OVERFLOW_COMPARISON);
5693 }
5694 }
5695 }
5698 }
5699 \f
5700 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5701 bit value. Arrange things so the extra bits will be set to zero if and
5702 only if C is signed-extended to its full width. If MASK is nonzero,
5703 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5705 static tree
5707 {
5710 tree temp;
5715 /* We work by getting just the sign bit into the low-order bit, then
5716 into the high-order bit, then sign-extend. We then XOR that value
5717 with C. */
5721 /* We must use a signed type in order to get an arithmetic right shift.
5722 However, we must also avoid introducing accidental overflows, so that
5723 a subsequent call to integer_zerop will work. Hence we must
5724 do the type conversion here. At this point, the constant is either
5725 zero or one, and the conversion to a signed type can never overflow.
5726 We could get an overflow if this conversion is done anywhere else. */
5736 /* If necessary, convert the type back to match the type of C. */
5742 }
5743 \f
5744 /* Find ways of folding logical expressions of LHS and RHS:
5745 Try to merge two comparisons to the same innermost item.
5746 Look for range tests like "ch >= '0' && ch <= '9'".
5747 Look for combinations of simple terms on machines with expensive branches
5748 and evaluate the RHS unconditionally.
5750 For example, if we have p->a == 2 && p->b == 4 and we can make an
5751 object large enough to span both A and B, we can do this with a comparison
5752 against the object ANDed with the a mask.
5754 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5755 operations to do this with one comparison.
5757 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5758 function and the one above.
5760 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5761 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5763 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5764 two operands.
5766 We return the simplified tree or 0 if no optimization is possible. */
5768 static tree
5771 {
5772 /* If this is the "or" of two comparisons, we can do something if
5773 the comparisons are NE_EXPR. If this is the "and", we can do something
5774 if the comparisons are EQ_EXPR. I.e.,
5775 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5777 WANTED_CODE is this operation code. For single bit fields, we can
5778 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5779 comparison for one-bit fields. */
5801 /* Start by getting the comparison codes. Fail if anything is volatile.
5802 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5803 it were surrounded with a NE_EXPR. */
5812 {
5816 }
5819 {
5823 }
5834 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5837 {
5838 tree result;
5841 {
5846 }
5849 {
5855 }
5856 }
5861 /* If the RHS can be evaluated unconditionally and its operands are
5862 simple, it wins to evaluate the RHS unconditionally on machines
5863 with expensive branches. In this case, this isn't a comparison
5864 that can be merged. Avoid doing this if the RHS is a floating-point
5865 comparison since those can trap. */
5872 {
5873 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5879 {
5885 }
5887 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5893 {
5899 }
5902 {
5904 {
5907 }
5909 }
5910 }
5912 /* See if the comparisons can be merged. Then get all the parameters for
5913 each side. */
5937 /* It must be true that the inner operation on the lhs of each
5938 comparison must be the same if we are to be able to do anything.
5939 Then see if we have constants. If not, the same must be true for
5940 the rhs's. */
5951 else
5954 /* If either comparison code is not correct for our logical operation,
5955 fail. However, we can convert a one-bit comparison against zero into
5956 the opposite comparison against that bit being set in the field. */
5960 {
5962 {
5963 /* Make the left operand unsigned, since we are only interested
5964 in the value of one bit. Otherwise we are doing the wrong
5965 thing below. */
5968 }
5969 else
5971 }
5973 /* This is analogous to the code for l_const above. */
5975 {
5977 {
5980 }
5981 else
5983 }
5985 /* See if we can find a mode that contains both fields being compared on
5986 the left. If we can't, fail. Otherwise, update all constants and masks
5987 to be relative to a field of that size. */
5992 volatilep);
6002 {
6005 }
6013 {
6021 {
6025 }
6026 }
6028 {
6036 {
6040 }
6041 }
6043 /* If the right sides are not constant, do the same for it. Also,
6044 disallow this optimization if a size or signedness mismatch occurs
6045 between the left and right sides. */
6047 {
6050 /* Make sure the two fields on the right
6051 correspond to the left without being swapped. */
6059 volatilep);
6069 {
6072 }
6081 /* Make a mask that corresponds to both fields being compared.
6082 Do this for both items being compared. If the operands are the
6083 same size and the bits being compared are in the same position
6084 then we can do this by masking both and comparing the masked
6085 results. */
6089 {
6102 }
6104 /* There is still another way we can do something: If both pairs of
6105 fields being compared are adjacent, we may be able to make a wider
6106 field containing them both.
6108 Note that we still must mask the lhs/rhs expressions. Furthermore,
6109 the mask must be shifted to account for the shift done by
6110 make_bit_field_ref. */
6115 {
6116 tree type;
6130 /* Convert to the smaller type before masking out unwanted bits. */
6133 {
6135 {
6139 }
6141 {
6145 }
6146 }
6156 }
6159 }
6161 /* Handle the case of comparisons with constants. If there is something in
6162 common between the masks, those bits of the constants must be the same.
6163 If not, the condition is always false. Test for this to avoid generating
6164 incorrect code below. */
6169 {
6171 {
6174 }
6175 else
6176 {
6179 }
6180 }
6182 /* Construct the expression we will return. First get the component
6183 reference we will make. Unless the mask is all ones the width of
6184 that field, perform the mask operation. Then compare with the
6185 merged constant. */
6191 {
6194 }
6199 fold_truthop_exit:
6202 }
6203 \f
6204 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
6205 constant. */
6207 static tree
6210 {
6213 tree comp_const;
6214 tree minmax_const;
6216 tree inner;
6227 /* If something does not permit us to optimize, return the original tree. */
6235 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6236 and GT_EXPR, doing the rest with recursive calls using logical
6237 simplifications. */
6239 {
6241 {
6242 tree tem
6249 }
6252 return
6254 optimize_minmax_comparison
6256 optimize_minmax_comparison
6261 /* MAX (X, 0) == 0 -> X <= 0 */
6265 /* MAX (X, 0) == 5 -> X == 5 */
6269 /* MAX (X, 0) == -1 -> false */
6273 /* MIN (X, 0) == 0 -> X >= 0 */
6277 /* MIN (X, 0) == 5 -> false */
6280 else
6281 /* MIN (X, 0) == -1 -> X == -1 */
6286 /* MAX (X, 0) > 0 -> X > 0
6287 MAX (X, 0) > 5 -> X > 5 */
6291 /* MAX (X, 0) > -1 -> true */
6295 /* MIN (X, 0) > 0 -> false
6296 MIN (X, 0) > 5 -> false */
6299 else
6300 /* MIN (X, 0) > -1 -> X > -1 */
6305 }
6306 }
6307 \f
6308 /* T is an integer expression that is being multiplied, divided, or taken a
6309 modulus (CODE says which and what kind of divide or modulus) by a
6310 constant C. See if we can eliminate that operation by folding it with
6311 other operations already in T. WIDE_TYPE, if non-null, is a type that
6312 should be used for the computation if wider than our type.
6314 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6315 (X * 2) + (Y * 4). We must, however, be assured that either the original
6316 expression would not overflow or that overflow is undefined for the type
6317 in the language in question.
6319 If we return a non-null expression, it is an equivalent form of the
6320 original computation, but need not be in the original type.
6322 We set *STRICT_OVERFLOW_P to true if the return values depends on
6323 signed overflow being undefined. Otherwise we do not change
6324 *STRICT_OVERFLOW_P. */
6326 static tree
6329 {
6330 /* To avoid exponential search depth, refuse to allow recursion past
6331 three levels. Beyond that (1) it's highly unlikely that we'll find
6332 something interesting and (2) we've probably processed it before
6333 when we built the inner expression. */
6336 tree ret;
6341 depth++;
6343 depth--;
6346 }
6348 static tree
6351 {
6362 /* Don't deal with constants of zero here; they confuse the code below. */
6372 /* Note that we need not handle conditional operations here since fold
6373 already handles those cases. So just do arithmetic here. */
6375 {
6377 /* For a constant, we can always simplify if we are a multiply
6378 or (for divide and modulus) if it is a multiple of our constant. */
6386 /* If op0 is an expression ... */
6392 /* ... and has wrapping overflow, and its type is smaller
6393 than ctype, then we cannot pass through as widening. */
6399 /* ... or this is a truncation (t is narrower than op0),
6400 then we cannot pass through this narrowing. */
6403 /* ... or signedness changes for division or modulus,
6404 then we cannot pass through this conversion. */
6408 /* ... or has undefined overflow while the converted to
6409 type has not, we cannot do the operation in the inner type
6410 as that would introduce undefined overflow. */
6415 /* Pass the constant down and see if we can make a simplification. If
6416 we can, replace this expression with the inner simplification for
6417 possible later conversion to our or some other type. */
6422 code == MULT_EXPR
6424 strict_overflow_p))))
6429 /* If widening the type changes it from signed to unsigned, then we
6430 must avoid building ABS_EXPR itself as unsigned. */
6432 {
6436 {
6439 }
6441 }
6442 /* If the constant is negative, we cannot simplify this. */
6445 /* FALLTHROUGH */
6453 /* If widening the type changes the signedness, then we can't perform
6454 this optimization as that changes the result. */
6458 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6464 {
6471 }
6475 /* If the second operand is constant, this is a multiplication
6476 or floor division, by a power of two, so we can treat it that
6477 way unless the multiplier or divisor overflows. Signed
6478 left-shift overflow is implementation-defined rather than
6479 undefined in C90, so do not convert signed left shift into
6480 multiplication. */
6483 /* const_binop may not detect overflow correctly,
6484 so check for it explicitly here. */
6489 size_one_node,
6494 ctype,
6496 t1),
6501 /* See if we can eliminate the operation on both sides. If we can, we
6502 can return a new PLUS or MINUS. If we can't, the only remaining
6503 cases where we can do anything are if the second operand is a
6504 constant. */
6510 /* If not multiplication, we can only do this if both operands
6511 are divisible by c. */
6514 {
6519 }
6521 /* If this was a subtraction, negate OP1 and set it to be an addition.
6522 This simplifies the logic below. */
6524 {
6526 /* If OP1 was not easily negatable, the constant may be OP0. */
6528 {
6535 }
6536 }
6541 /* If either OP1 or C are negative, this optimization is not safe for
6542 some of the division and remainder types while for others we need
6543 to change the code. */
6545 {
6553 }
6555 /* If it's a multiply or a division/modulus operation of a multiple
6556 of our constant, do the operation and verify it doesn't overflow. */
6559 {
6562 /* We allow the constant to overflow with wrapping semantics. */
6566 }
6567 else
6570 /* If we have an unsigned type is not a sizetype, we cannot widen
6571 the operation since it will change the result if the original
6572 computation overflowed. */
6578 /* If we were able to eliminate our operation from the first side,
6579 apply our operation to the second side and reform the PLUS. */
6583 /* The last case is if we are a multiply. In that case, we can
6584 apply the distributive law to commute the multiply and addition
6585 if the multiplication of the constants doesn't overflow. */
6591 op1);
6596 /* We have a special case here if we are doing something like
6597 (C * 8) % 4 since we know that's zero. */
6600 /* If the multiplication can overflow we cannot optimize this.
6601 ??? Until we can properly mark individual operations as
6602 not overflowing we need to treat sizetype special here as
6603 stor-layout relies on this opimization to make
6604 DECL_FIELD_BIT_OFFSET always a constant. */
6610 {
6613 }
6615 /* ... fall through ... */
6619 /* If we can extract our operation from the LHS, do so and return a
6620 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6621 do something only if the second operand is a constant. */
6635 /* If these are the same operation types, we can associate them
6636 assuming no overflow. */
6649 /* If these operations "cancel" each other, we have the main
6650 optimizations of this pass, which occur when either constant is a
6651 multiple of the other, in which case we replace this with either an
6652 operation or CODE or TCODE.
6654 If we have an unsigned type that is not a sizetype, we cannot do
6655 this since it will change the result if the original computation
6656 overflowed. */
6664 {
6666 {
6673 }
6675 {
6682 }
6683 }
6688 }
6691 }
6692 \f
6693 /* Return a node which has the indicated constant VALUE (either 0 or
6694 1), and is of the indicated TYPE. */
6696 tree
6698 {
6703 else
6705 }
6708 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6709 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6710 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6711 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6712 COND is the first argument to CODE; otherwise (as in the example
6713 given here), it is the second argument. TYPE is the type of the
6714 original expression. Return NULL_TREE if no simplification is
6715 possible. */
6717 static tree
6722 {
6729 /* This transformation is only worthwhile if we don't have to wrap
6730 arg in a SAVE_EXPR, and the operation can be simplified on at least
6731 one of the branches once its pushed inside the COND_EXPR. */
6736 {
6740 /* If this operand throws an expression, then it does not make
6741 sense to try to perform a logical or arithmetic operation
6742 involving it. */
6747 }
6748 else
6749 {
6754 }
6758 {
6762 else
6764 }
6766 {
6770 else
6772 }
6776 }
6778 \f
6779 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6781 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6782 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6783 ADDEND is the same as X.
6785 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6786 and finite. The problematic cases are when X is zero, and its mode
6787 has signed zeros. In the case of rounding towards -infinity,
6788 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6789 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6791 bool
6793 {
6797 /* Don't allow the fold with -fsignaling-nans. */
6801 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6805 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6810 /* The mode has signed zeros, and we have to honor their sign.
6811 In this situation, there is only one case we can return true for.
6812 X - 0 is the same as X unless rounding towards -infinity is
6813 supported. */
6815 }
6817 /* Subroutine of fold() that checks comparisons of built-in math
6818 functions against real constants.
6820 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6821 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6822 is the type of the result and ARG0 and ARG1 are the operands of the
6823 comparison. ARG1 must be a TREE_REAL_CST.
6825 The function returns the constant folded tree if a simplification
6826 can be made, and NULL_TREE otherwise. */
6828 static tree
6832 {
6833 REAL_VALUE_TYPE c;
6836 {
6842 {
6843 /* sqrt(x) < y is always false, if y is negative. */
6847 /* sqrt(x) > y is always true, if y is negative and we
6848 don't care about NaNs, i.e. negative values of x. */
6852 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6855 }
6857 {
6858 REAL_VALUE_TYPE c2;
6864 {
6865 /* sqrt(x) > y is x == +Inf, when y is very large. */
6870 /* sqrt(x) > y is always false, when y is very large
6871 and we don't care about infinities. */
6873 }
6875 /* sqrt(x) > c is the same as x > c*c. */
6878 }
6880 {
6881 REAL_VALUE_TYPE c2;
6887 {
6888 /* sqrt(x) < y is always true, when y is a very large
6889 value and we don't care about NaNs or Infinities. */
6893 /* sqrt(x) < y is x != +Inf when y is very large and we
6894 don't care about NaNs. */
6899 /* sqrt(x) < y is x >= 0 when y is very large and we
6900 don't care about Infinities. */
6905 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6914 dconst0)),
6917 c2)));
6918 }
6920 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6925 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6928 {
6933 dconst0)),
6936 c2)));
6937 }
6938 }
6939 }
6942 }
6944 /* Subroutine of fold() that optimizes comparisons against Infinities,
6945 either +Inf or -Inf.
6947 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6948 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6949 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6951 The function returns the constant folded tree if a simplification
6952 can be made, and NULL_TREE otherwise. */
6954 static tree
6957 {
6959 REAL_VALUE_TYPE max;
6960 tree temp;
6965 /* For negative infinity swap the sense of the comparison. */
6971 {
6973 /* x > +Inf is always false, if with ignore sNANs. */
6979 /* x <= +Inf is always true, if we don't case about NaNs. */
6983 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6986 {
6989 }
6994 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
7000 /* x < +Inf is always equal to x <= DBL_MAX. */
7006 /* x != +Inf is always equal to !(x > DBL_MAX). */
7018 }
7021 }
7023 /* Subroutine of fold() that optimizes comparisons of a division by
7024 a nonzero integer constant against an integer constant, i.e.
7025 X/C1 op C2.
7027 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7028 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
7029 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
7031 The function returns the constant folded tree if a simplification
7032 can be made, and NULL_TREE otherwise. */
7034 static tree
7037 {
7042 HOST_WIDE_INT hpart;
7047 /* We have to do this the hard way to detect unsigned overflow.
7048 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
7059 {
7064 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
7072 }
7074 {
7078 {
7097 }
7098 }
7099 else
7100 {
7101 /* A negative divisor reverses the relational operators. */
7107 {
7126 }
7127 }
7130 {
7151 {
7154 }
7159 {
7162 }
7167 {
7170 }
7175 {
7178 }
7183 }
7186 }
7189 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7190 equality/inequality test, then return a simplified form of the test
7191 using a sign testing. Otherwise return NULL. TYPE is the desired
7192 result type. */
7194 static tree
7197 tree result_type)
7198 {
7199 /* If this is testing a single bit, we can optimize the test. */
7203 {
7204 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7205 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7209 /* This is only a win if casting to a signed type is cheap,
7210 i.e. when arg00's type is not a partial mode. */
7213 {
7216 result_type,
7219 }
7220 }
7223 }
7225 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7226 equality/inequality test, then return a simplified form of
7227 the test using shifts and logical operations. Otherwise return
7228 NULL. TYPE is the desired result type. */
7230 tree
7233 {
7234 /* If this is testing a single bit, we can optimize the test. */
7238 {
7247 /* First, see if we can fold the single bit test into a sign-bit
7248 test. */
7250 result_type);
7254 /* Otherwise we have (A & C) != 0 where C is a single bit,
7255 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7256 Similarly for (A & C) == 0. */
7258 /* If INNER is a right shift of a constant and it plus BITNUM does
7259 not overflow, adjust BITNUM and INNER. */
7266 {
7269 }
7271 /* If we are going to be able to omit the AND below, we must do our
7272 operations as unsigned. If we must use the AND, we have a choice.
7273 Normally unsigned is faster, but for some machines signed is. */
7274 #ifdef LOAD_EXTEND_OP
7277 #else
7279 #endif
7295 /* Put the AND last so it can combine with more things. */
7298 /* Make sure to return the proper type. */
7302 }
7304 }
7306 /* Check whether we are allowed to reorder operands arg0 and arg1,
7307 such that the evaluation of arg1 occurs before arg0. */
7309 static bool
7311 {
7318 }
7320 /* Test whether it is preferable two swap two operands, ARG0 and
7321 ARG1, for example because ARG0 is an integer constant and ARG1
7322 isn't. If REORDER is true, only recommend swapping if we can
7323 evaluate the operands in reverse order. */
7325 bool
7327 {
7363 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7364 for commutative and comparison operators. Ensuring a canonical
7365 form allows the optimizers to find additional redundancies without
7366 having to explicitly check for both orderings. */
7372 /* Put SSA_NAMEs last. */
7378 /* Put variables last. */
7385 }
7387 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7388 ARG0 is extended to a wider type. */
7390 static tree
7393 {
7395 tree arg1_unw;
7404 #ifdef HAVE_canonicalize_funcptr_for_compare
7405 /* Disable this optimization if we're casting a function pointer
7406 type on targets that require function pointer canonicalization. */
7411 #endif
7418 /* If possible, express the comparison in the shorter mode. */
7438 /* If we are comparing with the integer that does not fit into the range
7439 of the shorter type, the result is known. */
7450 {
7477 }
7480 }
7482 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7483 ARG0 just the signedness is changed. */
7485 static tree
7488 {
7489 tree arg0_inner;
7499 #ifdef HAVE_canonicalize_funcptr_for_compare
7500 /* Disable this optimization if we're casting a function pointer
7501 type on targets that require function pointer canonicalization. */
7506 #endif
7526 else
7530 }
7532 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7533 step of the array. Reconstructs s and delta in the case of s *
7534 delta being an integer constant (and thus already folded). ADDR is
7535 the address. MULT is the multiplicative expression. If the
7536 function succeeds, the new address expression is returned.
7537 Otherwise NULL_TREE is returned. LOC is the location of the
7538 resulting expression. */
7540 static tree
7542 {
7546 tree itype;
7549 /* Strip the nops that might be added when converting op1 to sizetype. */
7552 /* Canonicalize op1 into a possibly non-constant delta
7553 and an INTEGER_CST s. */
7555 {
7562 {
7565 }
7567 {
7570 }
7571 else
7573 }
7575 {
7578 }
7579 else
7580 {
7581 /* Simulate we are delta * 1. */
7584 }
7587 {
7589 {
7590 tree domain;
7592 /* Remember if this was a multi-dimensional array. */
7606 {
7609 }
7610 else
7611 {
7612 /* Try if delta is a multiple of step. */
7617 }
7619 /* Only fold here if we can verify we do not overflow one
7620 dimension of a multi-dimensional array. */
7622 {
7623 tree tmp;
7638 }
7641 }
7642 else
7647 }
7649 /* We found the suitable array reference. So copy everything up to it,
7650 and replace the index. */
7658 {
7662 }
7670 }
7673 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7674 means A >= Y && A != MAX, but in this case we know that
7675 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7677 static tree
7679 {
7686 else
7695 {
7698 }
7700 {
7703 }
7704 else
7711 {
7712 /* Convert the pointer types into integer before taking the difference. */
7716 }
7717 else
7724 }
7726 /* Fold a sum or difference of at least one multiplication.
7727 Returns the folded tree or NULL if no simplification could be made. */
7729 static tree
7732 {
7736 /* (A * C) +- (B * C) -> (A+-B) * C.
7737 (A * C) +- A -> A * (C+-1).
7738 We are most concerned about the case where C is a constant,
7739 but other combinations show up during loop reduction. Since
7740 it is not difficult, try all four possibilities. */
7743 {
7746 }
7748 {
7751 }
7752 else
7753 {
7754 /* We cannot generate constant 1 for fract. */
7759 }
7761 {
7764 }
7766 {
7768 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7769 the purpose of this canonicalization. */
7773 {
7776 }
7777 else
7779 }
7780 else
7781 {
7782 /* We cannot generate constant 1 for fract. */
7787 }
7799 /* No identical multiplicands; see if we can find a common
7800 power-of-two factor in non-power-of-two multiplies. This
7801 can help in multi-dimensional array access. */
7804 {
7807 tree maybe_same;
7811 /* Move min of absolute values to int11. */
7814 {
7819 }
7820 else
7824 /* The remainder should not be a constant, otherwise we
7825 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7826 increased the number of multiplications necessary. */
7828 {
7836 }
7837 }
7847 }
7849 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7850 specified by EXPR into the buffer PTR of length LEN bytes.
7851 Return the number of bytes placed in the buffer, or zero
7852 upon failure. */
7854 static int
7856 {
7867 {
7871 else
7876 {
7883 else
7885 }
7886 else
7889 }
7891 }
7894 /* Subroutine of native_encode_expr. Encode the REAL_CST
7895 specified by EXPR into the buffer PTR of length LEN bytes.
7896 Return the number of bytes placed in the buffer, or zero
7897 upon failure. */
7899 static int
7901 {
7907 /* There are always 32 bits in each long, no matter the size of
7908 the hosts long. We handle floating point representations with
7909 up to 192 bits. */
7920 {
7925 {
7932 else
7934 }
7935 else
7938 }
7940 }
7942 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7943 specified by EXPR into the buffer PTR of length LEN bytes.
7944 Return the number of bytes placed in the buffer, or zero
7945 upon failure. */
7947 static int
7949 {
7951 tree part;
7962 }
7965 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7966 specified by EXPR into the buffer PTR of length LEN bytes.
7967 Return the number of bytes placed in the buffer, or zero
7968 upon failure. */
7970 static int
7972 {
7982 {
7984 {
7987 }
7988 else
7992 {
7995 }
7996 else
7997 {
8001 }
8003 }
8005 }
8008 /* Subroutine of native_encode_expr. Encode the STRING_CST
8009 specified by EXPR into the buffer PTR of length LEN bytes.
8010 Return the number of bytes placed in the buffer, or zero
8011 upon failure. */
8013 static int
8015 {
8017 HOST_WIDE_INT total_bytes;
8028 {
8032 }
8033 else
8036 }
8039 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
8040 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
8041 buffer PTR of length LEN bytes. Return the number of bytes
8042 placed in the buffer, or zero upon failure. */
8044 int
8046 {
8048 {
8066 }
8067 }
8070 /* Subroutine of native_interpret_expr. Interpret the contents of
8071 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8072 If the buffer cannot be interpreted, return NULL_TREE. */
8074 static tree
8076 {
8090 {
8093 {
8100 else
8102 }
8103 else
8109 else
8112 }
8115 }
8118 /* Subroutine of native_interpret_expr. Interpret the contents of
8119 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8120 If the buffer cannot be interpreted, return NULL_TREE. */
8122 static tree
8124 {
8129 /* There are always 32 bits in each long, no matter the size of
8130 the hosts long. We handle floating point representations with
8131 up to 192 bits. */
8132 REAL_VALUE_TYPE r;
8143 {
8146 {
8153 else
8155 }
8156 else
8161 }
8165 }
8168 /* Subroutine of native_interpret_expr. Interpret the contents of
8169 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8170 If the buffer cannot be interpreted, return NULL_TREE. */
8172 static tree
8174 {
8189 }
8192 /* Subroutine of native_interpret_expr. Interpret the contents of
8193 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8194 If the buffer cannot be interpreted, return NULL_TREE. */
8196 static tree
8198 {
8210 {
8215 }
8217 }
8220 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8221 the buffer PTR of length LEN as a constant of type TYPE. For
8222 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8223 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8224 return NULL_TREE. */
8226 tree
8228 {
8230 {
8247 }
8248 }
8251 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
8252 TYPE at compile-time. If we're unable to perform the conversion
8253 return NULL_TREE. */
8255 static tree
8257 {
8258 /* We support up to 512-bit values (for V8DFmode). */
8262 /* Check that the host and target are sane. */
8271 }
8273 /* Build an expression for the address of T. Folds away INDIRECT_REF
8274 to avoid confusing the gimplify process. */
8276 tree
8278 {
8279 /* The size of the object is not relevant when talking about its address. */
8283 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8286 {
8290 {
8293 }
8294 }
8296 {
8301 }
8302 else
8303 {
8306 }
8309 }
8311 /* Build an expression for the address of T. */
8313 tree
8315 {
8319 }
8321 /* Fold a unary expression of code CODE and type TYPE with operand
8322 OP0. Return the folded expression if folding is successful.
8323 Otherwise, return NULL_TREE. */
8325 tree
8327 {
8328 tree tem;
8329 tree arg0;
8337 {
8340 {
8341 /* Don't use STRIP_NOPS, because signedness of argument type
8342 matters. */
8344 }
8345 else
8346 {
8347 /* Strip any conversions that don't change the mode. This
8348 is safe for every expression, except for a comparison
8349 expression because its signedness is derived from its
8350 operands.
8352 Note that this is done as an internal manipulation within
8353 the constant folder, in order to find the simplest
8354 representation of the arguments so that their form can be
8355 studied. In any cases, the appropriate type conversions
8356 should be put back in the tree that will get out of the
8357 constant folder. */
8359 }
8360 }
8363 {
8370 {
8384 /* If this was a conversion, and all we did was to move into
8385 inside the COND_EXPR, bring it back out. But leave it if
8386 it is a conversion from integer to integer and the
8387 result precision is no wider than a word since such a
8388 conversion is cheap and may be optimized away by combine,
8389 while it couldn't if it were outside the COND_EXPR. Then return
8390 so we don't get into an infinite recursion loop taking the
8391 conversion out and then back in. */
8403 && (INTEGRAL_TYPE_P
8407 {
8416 }
8418 }
8420 {
8422 {
8426 }
8430 integer_one_node),
8432 integer_zero_node));
8433 }
8434 }
8437 {
8439 /* Re-association barriers around constants and other re-association
8440 barriers can be removed. */
8446 CASE_CONVERT:
8452 /* If we have (type) (a CMP b) and type is an integral type, return
8453 new expression involving the new type. */
8458 /* Handle cases of two conversions in a row. */
8460 {
8482 /* In addition to the cases of two conversions in a row
8483 handled below, if we are converting something to its own
8484 type via an object of identical or wider precision, neither
8485 conversion is needed. */
8492 /* Likewise, if the intermediate and initial types are either both
8493 float or both integer, we don't need the middle conversion if the
8494 former is wider than the latter and doesn't change the signedness
8495 (for integers). Avoid this if the final type is a pointer since
8496 then we sometimes need the middle conversion. Likewise if the
8497 final type has a precision not equal to the size of its mode. */
8506 && ! final_ptr
8510 /* If we have a sign-extension of a zero-extended value, we can
8511 replace that by a single zero-extension. */
8517 /* Two conversions in a row are not needed unless:
8518 - some conversion is floating-point (overstrict for now), or
8519 - some conversion is a vector (overstrict for now), or
8520 - the intermediate type is narrower than both initial and
8521 final, or
8522 - the intermediate type and innermost type differ in signedness,
8523 and the outermost type is wider than the intermediate, or
8524 - the initial type is a pointer type and the precisions of the
8525 intermediate and final types differ, or
8526 - the final type is a pointer type and the precisions of the
8527 initial and intermediate types differ. */
8541 }
8543 /* Handle (T *)&A.B.C for A being of type T and B and C
8544 living at offset zero. This occurs frequently in
8545 C++ upcasting and then accessing the base. */
8549 {
8551 tree offset;
8557 /* If the reference was to a (constant) zero offset, we can use
8558 the address of the base if it has the same base type
8559 as the result type. */
8565 }
8569 /* Detect assigning a bitfield. */
8571 && DECL_BIT_FIELD
8573 {
8574 /* Don't leave an assignment inside a conversion
8575 unless assigning a bitfield. */
8577 /* First do the assignment, then return converted constant. */
8583 }
8585 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8586 constants (if x has signed type, the sign bit cannot be set
8587 in c). This folds extension into the BIT_AND_EXPR.
8588 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8589 very likely don't have maximal range for their precision and this
8590 transformation effectively doesn't preserve non-maximal ranges. */
8594 {
8605 <= HOST_BITS_PER_WIDE_INT
8607 {
8614 #ifdef LOAD_EXTEND_OP
8616 && !flag_syntax_only
8619 {
8623 }
8624 #endif
8625 }
8627 {
8633 }
8634 }
8636 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8637 when one of the new casts will fold away. Conservatively we assume
8638 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8644 {
8652 }
8654 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8655 of the same precision, and X is an integer type not narrower than
8656 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8662 {
8668 }
8670 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8671 type of X and Y (integer types only). */
8676 {
8677 /* Be careful not to introduce new overflows. */
8678 tree mult_type;
8681 else
8685 {
8692 }
8693 }
8714 /* For integral conversions with the same precision or pointer
8715 conversions use a NOP_EXPR instead. */
8723 /* Strip inner integral conversions that do not change the precision. */
8747 /* Convert fabs((double)float) into (double)fabsf(float). */
8750 {
8756 targ0));
8757 }
8758 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8764 /* Strip sign ops from argument. */
8766 {
8771 }
8778 {
8784 }
8786 {
8791 }
8801 /* Convert ~ (-A) to A - 1. */
8806 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8815 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8830 /* Perform BIT_NOT_EXPR on each element individually. */
8832 {
8837 {
8839 {
8845 }
8846 else
8849 }
8852 }
8857 /* The argument to invert_truthvalue must have Boolean type. */
8861 /* Note that the operand of this must be an int
8862 and its values must be 0 or 1.
8863 ("true" is a fixed value perhaps depending on the language,
8864 but we don't handle values other than 1 correctly yet.) */
8879 {
8887 }
8889 {
8894 }
8896 {
8900 {
8909 }
8910 }
8922 {
8930 }
8932 {
8936 }
8938 {
8942 {
8951 }
8952 }
8956 /* Fold *&X to X if X is an lvalue. */
8958 {
8965 }
8971 }
8974 /* If the operation was a conversion do _not_ mark a resulting constant
8975 with TREE_OVERFLOW if the original constant was not. These conversions
8976 have implementation defined behavior and retaining the TREE_OVERFLOW
8977 flag here would confuse later passes such as VRP. */
8978 tree
8981 {
8990 }
8992 /* Fold a binary expression of code CODE and type TYPE with operands
8993 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8994 Return the folded expression if folding is successful. Otherwise,
8995 return NULL_TREE. */
8997 static tree
8999 {
9006 else
9009 /* MIN (MAX (a, b), b) == b. */
9014 /* MIN (MAX (b, a), b) == b. */
9020 /* MIN (a, MAX (a, b)) == a. */
9026 /* MIN (a, MAX (b, a)) == a. */
9033 }
9035 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9036 by changing CODE to reduce the magnitude of constants involved in
9037 ARG0 of the comparison.
9038 Returns a canonicalized comparison tree if a simplification was
9039 possible, otherwise returns NULL_TREE.
9040 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9041 valid if signed overflow is undefined. */
9043 static tree
9047 {
9053 /* Match A +- CST code arg1 and CST code arg1. We can change the
9054 first form only if overflow is undefined. */
9056 /* In principle pointers also have undefined overflow behavior,
9057 but that causes problems elsewhere. */
9065 /* Identify the constant in arg0 and its sign. */
9068 else
9072 /* Overflowed constants and zero will cause problems. */
9077 /* See if we can reduce the magnitude of the constant in
9078 arg0 by changing the comparison code. */
9080 {
9081 /* CST <= arg1 -> CST-1 < arg1. */
9084 /* -CST < arg1 -> -CST-1 <= arg1. */
9087 /* CST > arg1 -> CST-1 >= arg1. */
9090 /* -CST >= arg1 -> -CST-1 > arg1. */
9093 else
9095 /* arg1 code' CST' might be more canonical. */
9097 }
9098 else
9099 {
9100 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9104 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9108 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9112 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9116 else
9119 }
9121 /* Now build the constant reduced in magnitude. But not if that
9122 would produce one outside of its types range. */
9130 /* We cannot swap the comparison here as that would cause us to
9131 endlessly recurse. */
9139 /* If swapping might yield to a more canonical form, do so. */
9142 else
9144 }
9146 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9147 overflow further. Try to decrease the magnitude of constants involved
9148 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9149 and put sole constants at the second argument position.
9150 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9152 static tree
9155 {
9156 tree t;
9161 /* Try canonicalization by simplifying arg0. */
9166 {
9170 }
9172 /* Try canonicalization by simplifying arg1 using the swapped
9173 comparison. */
9181 }
9183 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9184 space. This is used to avoid issuing overflow warnings for
9185 expressions like &p->x which can not wrap. */
9187 static bool
9189 {
9200 {
9203 }
9206 else
9207 {
9210 }
9225 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9226 array. */
9228 {
9229 HOST_WIDE_INT base_size;
9234 }
9237 }
9239 /* Subroutine of fold_binary. This routine performs all of the
9240 transformations that are common to the equality/inequality
9241 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9242 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9243 fold_binary should call fold_binary. Fold a comparison with
9244 tree code CODE and type TYPE with operands OP0 and OP1. Return
9245 the folded comparison or NULL_TREE. */
9247 static tree
9250 {
9263 /* If one arg is a real or integer constant, put it last. */
9267 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
9274 {
9278 tree lhs;
9285 /* If the constant operation overflowed this can be
9286 simplified as a comparison against INT_MAX/INT_MIN. */
9289 {
9293 /* Get the sign of the constant on the lhs if the
9294 operation were VARIABLE + CONST1. */
9298 /* The sign of the constant determines if we overflowed
9299 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9300 Canonicalize to the INT_MIN overflow by swapping the comparison
9301 if necessary. */
9305 /* We now can look at the canonicalized case
9306 VARIABLE + 1 CODE2 INT_MIN
9307 and decide on the result. */
9316 }
9321 {
9323 "when changing X +- C1 cmp C2 to "
9325 WARN_STRICT_OVERFLOW_COMPARISON);
9327 }
9328 }
9330 /* For comparisons of pointers we can decompose it to a compile time
9331 comparison of the base objects and the offsets into the object.
9332 This requires at least one operand being an ADDR_EXPR or a
9333 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9339 {
9346 /* Get base and offset for the access. Strip ADDR_EXPR for
9347 get_inner_reference, but put it back by stripping INDIRECT_REF
9348 off the base object if possible. indirect_baseN will be true
9349 if baseN is not an address but refers to the object itself. */
9352 {
9358 else
9360 }
9362 {
9365 }
9369 {
9375 else
9377 }
9379 {
9382 }
9384 /* If we have equivalent bases we might be able to simplify. */
9387 {
9388 /* We can fold this expression to a constant if the non-constant
9389 offset parts are equal. */
9397 {
9404 "occur when comparing P +- C1 with "
9406 WARN_STRICT_OVERFLOW_CONDITIONAL);
9409 {
9423 }
9424 }
9425 /* We can simplify the comparison to a comparison of the variable
9426 offset parts if the constant offset parts are equal.
9427 Be careful to use signed size type here because otherwise we
9428 mess with array offsets in the wrong way. This is possible
9429 because pointer arithmetic is restricted to retain within an
9430 object and overflow on pointer differences is undefined as of
9431 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9435 {
9436 tree signed_size_type_node;
9439 /* By converting to signed size type we cover middle-end pointer
9440 arithmetic which operates on unsigned pointer types of size
9441 type size and ARRAY_REF offsets which are properly sign or
9442 zero extended from their type in case it is narrower than
9443 size type. */
9446 else
9448 offset0);
9451 else
9453 offset1);
9460 "occur when comparing P +- C1 with "
9462 WARN_STRICT_OVERFLOW_COMPARISON);
9465 }
9466 }
9467 /* For non-equal bases we can simplify if they are addresses
9468 of local binding decls or constants. */
9470 /* We know that !operand_equal_p (base0, base1, 0)
9471 because the if condition was false. But make
9472 sure two decls are not the same. */
9486 {
9493 }
9494 /* For equal offsets we can simplify to a comparison of the
9495 base addresses. */
9497 && (indirect_base0
9499 && (indirect_base1
9504 {
9510 }
9511 }
9513 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9514 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9515 the resulting offset is smaller in absolute value than the
9516 original one. */
9524 {
9529 tree cst;
9531 "occur when combining constants around "
9534 /* Put the constant on the side where it doesn't overflow and is
9535 of lower absolute value than before. */
9541 {
9544 variable1,
9548 }
9555 {
9560 variable2);
9561 }
9562 }
9564 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9565 signed arithmetic case. That form is created by the compiler
9566 often enough for folding it to be of value. One example is in
9567 computing loop trip counts after Operator Strength Reduction. */
9573 {
9582 "eliminating multiplication in comparison "
9584 WARN_STRICT_OVERFLOW_COMPARISON);
9586 /* If const1 is negative we swap the sense of the comparison. */
9591 }
9598 {
9606 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9612 /* (-a) CMP (-b) -> b CMP a */
9619 {
9620 REAL_VALUE_TYPE cst;
9623 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9630 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9631 /* a CMP (-0) -> a CMP 0 */
9636 /* x != NaN is always true, other ops are always false. */
9639 {
9642 }
9644 /* Fold comparisons against infinity. */
9647 {
9651 }
9652 }
9654 /* If this is a comparison of a real constant with a PLUS_EXPR
9655 or a MINUS_EXPR of a real constant, we can convert it into a
9656 comparison with a revised real constant as long as no overflow
9657 occurs when unsafe_math_optimizations are enabled. */
9669 /* Likewise, we can simplify a comparison of a real constant with
9670 a MINUS_EXPR whose first operand is also a real constant, i.e.
9671 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9672 floating-point types only if -fassociative-math is set. */
9683 /* Fold comparisons against built-in math functions. */
9685 && flag_unsafe_math_optimizations
9687 {
9691 {
9695 }
9696 }
9697 }
9701 {
9702 /* If we are widening one operand of an integer comparison,
9703 see if the other operand is similarly being widened. Perhaps we
9704 can do the comparison in the narrower type. */
9709 /* Or if we are changing signedness. */
9713 }
9715 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9716 constant, we can simplify it. */
9721 {
9725 }
9727 /* Simplify comparison of something with itself. (For IEEE
9728 floating-point, we can only do some of these simplifications.) */
9730 {
9732 {
9747 /* For NE, we can only do this simplification if integer
9748 or we don't honor IEEE floating point NaNs. */
9752 /* ... fall through ... */
9758 }
9759 }
9761 /* If we are comparing an expression that just has comparisons
9762 of two integer values, arithmetic expressions of those comparisons,
9763 and constants, we can simplify it. There are only three cases
9764 to check: the two values can either be equal, the first can be
9765 greater, or the second can be greater. Fold the expression for
9766 those three values. Since each value must be 0 or 1, we have
9767 eight possibilities, each of which corresponds to the constant 0
9768 or 1 or one of the six possible comparisons.
9770 This handles common cases like (a > b) == 0 but also handles
9771 expressions like ((x > y) - (y > x)) > 0, which supposedly
9772 occur in macroized code. */
9775 {
9780 /* Don't handle degenerate cases here; they should already
9781 have been handled anyway. */
9790 {
9794 /* We can't just pass T to eval_subst in case cval1 or cval2
9795 was the same as ARG1. */
9797 tree high_result
9801 arg1);
9802 tree equal_result
9806 arg1);
9807 tree low_result
9811 arg1);
9813 /* All three of these results should be 0 or 1. Confirm they are.
9814 Then use those values to select the proper code to use. */
9819 {
9820 /* Make a 3-bit mask with the high-order bit being the
9821 value for `>', the next for '=', and the low for '<'. */
9825 {
9827 /* Always false. */
9848 /* Always true. */
9850 }
9853 {
9857 }
9859 }
9860 }
9861 }
9863 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9864 into a single range test. */
9872 {
9876 }
9878 /* Fold ~X op ~Y as Y op X. */
9881 {
9887 }
9889 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9892 {
9898 }
9901 }
9904 /* Subroutine of fold_binary. Optimize complex multiplications of the
9905 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9906 argument EXPR represents the expression "z" of type TYPE. */
9908 static tree
9910 {
9915 {
9918 }
9920 {
9923 }
9924 else
9925 {
9929 }
9938 }
9941 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9942 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9943 guarantees that P and N have the same least significant log2(M) bits.
9944 N is not otherwise constrained. In particular, N is not normalized to
9945 0 <= N < M as is common. In general, the precise value of P is unknown.
9946 M is chosen as large as possible such that constant N can be determined.
9948 Returns M and sets *RESIDUE to N.
9950 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9951 account. This is not always possible due to PR 35705.
9952 */
9954 static unsigned HOST_WIDE_INT
9957 {
9964 {
9967 {
9969 tree offset;
9977 {
9980 else
9981 /* We don't handle more complicated offset expressions. */
9983 }
9984 }
9989 }
9991 {
9999 allow_func_align);
10005 {
10008 }
10010 {
10013 {
10016 /* Compute the greatest power-of-2 divisor of op1. */
10020 /* If align is non-zero and less than *modulus, replace
10021 *modulus with align., If align is 0, then either op1 is 0
10022 or the greatest power-of-2 divisor of op1 doesn't fit in an
10023 unsigned HOST_WIDE_INT. In either case, no additional
10024 constraint is imposed. */
10029 }
10030 }
10031 }
10033 /* If we get here, we were unable to determine anything useful about the
10034 expression. */
10036 }
10039 /* Fold a binary expression of code CODE and type TYPE with operands
10040 OP0 and OP1. LOC is the location of the resulting expression.
10041 Return the folded expression if folding is successful. Otherwise,
10042 return NULL_TREE. */
10044 tree
10047 {
10061 /* Strip any conversions that don't change the mode. This is
10062 safe for every expression, except for a comparison expression
10063 because its signedness is derived from its operands. So, in
10064 the latter case, only strip conversions that don't change the
10065 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10066 preserved.
10068 Note that this is done as an internal manipulation within the
10069 constant folder, in order to find the simplest representation
10070 of the arguments so that their form can be studied. In any
10071 cases, the appropriate type conversions should be put back in
10072 the tree that will get out of the constant folder. */
10075 {
10078 }
10079 else
10080 {
10083 }
10085 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10086 constant but we can't do arithmetic on them. */
10093 {
10095 {
10096 /* Make sure type and arg0 have the same saturating flag. */
10100 }
10103 else
10107 {
10111 }
10112 }
10114 /* If this is a commutative operation, and ARG0 is a constant, move it
10115 to ARG1 to reduce the number of tests below. */
10120 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10122 First check for cases where an arithmetic operation is applied to a
10123 compound, conditional, or comparison operation. Push the arithmetic
10124 operation inside the compound or conditional to see if any folding
10125 can then be done. Convert comparison to conditional for this purpose.
10126 The also optimizes non-constant cases that used to be done in
10127 expand_expr.
10129 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10130 one of the operands is a comparison and the other is a comparison, a
10131 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10132 code below would make the expression more complex. Change it to a
10133 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10134 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10146 {
10150 boolean_type_node,
10158 }
10162 {
10164 {
10170 }
10173 {
10179 }
10182 {
10188 }
10191 {
10197 }
10198 }
10201 {
10203 /* 0 +p index -> (type)index */
10207 /* PTR +p 0 -> PTR */
10211 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10217 arg1),
10219 arg0)));
10221 /* index +p PTR -> PTR +p index */
10228 /* (PTR +p B) +p A -> PTR +p (B + A) */
10230 {
10231 tree inner;
10240 }
10242 /* PTR_CST +p CST -> CST1 */
10247 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10248 of the array. Loop optimizer sometimes produce this type of
10249 expressions. */
10251 {
10256 }
10261 /* A + (-B) -> A - B */
10267 /* (-A) + B -> B - A */
10276 {
10277 /* Convert ~A + 1 to -A. */
10284 /* ~X + X is -1. */
10287 {
10292 {
10295 }
10296 }
10298 /* X + ~X is -1. */
10301 {
10306 {
10309 }
10310 }
10312 /* X + (X / CST) * -CST is X % CST. */
10317 {
10326 cst0));
10327 }
10328 }
10330 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
10331 same or one. Make sure type is not saturating.
10332 fold_plusminus_mult_expr will re-associate. */
10337 {
10341 }
10344 {
10348 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10349 with a constant, and the two constants have no bits in common,
10350 we should treat this as a BIT_IOR_EXPR since this may produce more
10351 simplifications. */
10359 {
10362 }
10364 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10365 (plus (plus (mult) (mult)) (foo)) so that we can
10366 take advantage of the factoring cases below. */
10373 {
10379 else
10392 parg0),
10394 marg)),
10398 return
10404 parg1)));
10405 }
10406 }
10407 else
10408 {
10409 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10413 /* Likewise if the operands are reversed. */
10417 /* Convert X + -C into X - C. */
10420 {
10426 }
10428 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10429 to __complex__ ( x, y ). This is not the same for SNaNs or
10430 if signed zeros are involved. */
10434 {
10441 {
10445 {
10451 }
10453 {
10459 }
10460 }
10461 }
10469 /* Convert x+x into x*2.0. */
10475 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10476 We associate floats only if the user has specified
10477 -fassociative-math. */
10481 {
10486 {
10487 tree tree0;
10490 }
10491 }
10492 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10493 We associate floats only if the user has specified
10494 -fassociative-math. */
10498 {
10503 {
10504 tree tree0;
10507 }
10508 }
10509 }
10511 bit_rotate:
10512 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10513 is a rotate of A by C1 bits. */
10514 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10515 is a rotate of A by B bits. */
10516 {
10518 tree rtype;
10527 /* Only create rotates in complete modes. Other cases are not
10528 expanded properly. */
10530 {
10546 {
10550 code0 == LSHIFT_EXPR
10554 }
10556 {
10564 TYPE_PRECISION
10568 return
10571 ? LROTATE_EXPR
10575 }
10577 {
10585 TYPE_PRECISION
10589 return fold_convert_loc
10592 ? LROTATE_EXPR
10596 }
10597 }
10598 }
10600 associate:
10601 /* In most languages, can't associate operations on floats through
10602 parentheses. Rather than remember where the parentheses were, we
10603 don't associate floats at all, unless the user has specified
10604 -fassociative-math.
10605 And, we need to make sure type is not saturating. */
10609 {
10614 /* Split both trees into variables, constants, and literals. Then
10615 associate each group together, the constants with literals,
10616 then the result with variables. This increases the chances of
10617 literals being recombined later and of generating relocatable
10618 expressions for the sum of a constant and literal. */
10623 /* With undefined overflow we can only associate constants
10624 with one variable. */
10628 {
10636 /* The only case we can still associate with two variables
10637 is if they are the same, modulo negation. */
10640 }
10642 /* Only do something if we found more than two objects. Otherwise,
10643 nothing has changed and we risk infinite recursion. */
10649 {
10650 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10659 /* Preserve the MINUS_EXPR if the negative part of the literal is
10660 greater than the positive part. Otherwise, the multiplicative
10661 folding code (i.e extract_muldiv) may be fooled in case
10662 unsigned constants are subtracted, like in the following
10663 example: ((X*2 + 4) - 8U)/2. */
10665 {
10669 {
10673 }
10674 else
10675 {
10679 }
10680 }
10682 {
10684 return
10688 else
10689 {
10692 return
10696 }
10697 }
10700 return
10703 }
10704 }
10709 /* Pointer simplifications for subtraction, simple reassociations. */
10711 {
10712 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10715 {
10725 }
10726 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10728 {
10735 }
10736 }
10737 /* A - (-B) -> A + B */
10742 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10753 /* Convert -A - 1 to ~A. */
10762 /* Convert -1 - A to ~A. */
10768 /* X - (X / CST) * CST is X % CST. */
10776 return
10782 {
10788 /* Fold A - (A & B) into ~B & A. */
10791 {
10793 {
10800 }
10802 {
10809 }
10810 }
10812 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10813 any power of 2 minus 1. */
10818 {
10824 {
10828 }
10829 }
10830 }
10832 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10836 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10837 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10838 (-ARG1 + ARG0) reduces to -ARG1. */
10842 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10843 __complex__ ( x, -y ). This is not the same for SNaNs or if
10844 signed zeros are involved. */
10848 {
10855 {
10859 {
10861 arg1r ? arg1r
10866 }
10868 {
10872 arg1i ? arg1i
10875 }
10876 }
10877 }
10879 /* Fold &x - &x. This can happen from &x.foo - &x.
10880 This is unsafe for certain floats even in non-IEEE formats.
10881 In IEEE, it is unsafe because it does wrong for NaNs.
10882 Also note that operand_equal_p is always false if an operand
10883 is volatile. */
10889 /* A - B -> A + (-B) if B is easily negatable. */
10892 /* Avoid this transformation if B is a positive REAL_CST. */
10901 /* Try folding difference of addresses. */
10902 {
10903 HOST_WIDE_INT diff;
10909 }
10911 /* Fold &a[i] - &a[j] to i-j. */
10916 {
10921 {
10929 }
10930 }
10933 && flag_unsafe_math_optimizations
10939 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10940 same or one. Make sure type is not saturating.
10941 fold_plusminus_mult_expr will re-associate. */
10946 {
10950 }
10955 /* (-A) * (-B) -> A * B */
10970 {
10975 /* Transform x * -1 into -x. Make sure to do the negation
10976 on the original operand with conversions not stripped
10977 because we can only strip non-sign-changing conversions. */
10980 /* Transform x * -C into -x * C if x is easily negatable. */
10989 tem);
10991 /* (a * (1 << b)) is (a << b) */
11001 /* (A + A) * C -> A * 2 * C */
11017 {
11020 "occur when simplifying "
11022 WARN_STRICT_OVERFLOW_MISC);
11024 }
11026 /* Optimize z * conj(z) for integer complex numbers. */
11033 }
11034 else
11035 {
11036 /* Maybe fold x * 0 to 0. The expressions aren't the same
11037 when x is NaN, since x * 0 is also NaN. Nor are they the
11038 same in modes with signed zeros, since multiplying a
11039 negative value by 0 gives -0, not +0. */
11044 /* In IEEE floating point, x*1 is not equivalent to x for snans.
11045 Likewise for complex arithmetic with signed zeros. */
11052 /* Transform x * -1.0 into -x. */
11059 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
11060 the result for floating point types due to rounding so it is applied
11061 only if -fassociative-math was specify. */
11066 {
11072 }
11074 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
11076 {
11079 {
11082 }
11083 }
11085 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11086 This is not the same for NaNs or if signed zeros are
11087 involved. */
11093 {
11096 return
11102 return
11107 }
11109 /* Optimize z * conj(z) for floating point complex numbers.
11110 Guarded by flag_unsafe_math_optimizations as non-finite
11111 imaginary components don't produce scalar results. */
11122 {
11126 /* Optimizations of root(...)*root(...). */
11128 {
11133 /* Optimize sqrt(x)*sqrt(x) as x. */
11139 /* Optimize root(x)*root(y) as root(x*y). */
11143 }
11145 /* Optimize expN(x)*expN(y) as expN(x+y). */
11147 {
11153 }
11155 /* Optimizations of pow(...)*pow(...). */
11159 {
11165 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11167 {
11172 }
11174 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11176 {
11181 }
11182 }
11184 /* Optimize tan(x)*cos(x) as sin(x). */
11193 {
11199 }
11201 /* Optimize x*pow(x,c) as pow(x,c+1). */
11205 {
11211 {
11213 REAL_VALUE_TYPE c;
11214 tree arg;
11220 }
11221 }
11223 /* Optimize pow(x,c)*x as pow(x,c+1). */
11227 {
11233 {
11235 REAL_VALUE_TYPE c;
11236 tree arg;
11242 }
11243 }
11245 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
11248 {
11252 {
11255 }
11256 }
11257 }
11258 }
11262 bit_ior:
11270 /* ~X | X is -1. */
11273 {
11277 }
11279 /* X | ~X is -1. */
11282 {
11286 }
11288 /* Canonicalize (X & C1) | C2. */
11292 {
11300 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11306 {
11310 }
11311 else
11312 {
11316 }
11318 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11323 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11324 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11325 mode which allows further optimizations. */
11335 {
11336 unsigned HOST_WIDE_INT mask
11340 {
11344 }
11345 }
11352 arg1);
11353 }
11355 /* (X & Y) | Y is (X, Y). */
11359 /* (X & Y) | X is (Y, X). */
11364 /* X | (X & Y) is (Y, X). */
11369 /* X | (Y & X) is (Y, X). */
11379 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11381 This results in more efficient code for machines without a NAND
11382 instruction. Combine will canonicalize to the first form
11383 which will allow use of NAND instructions provided by the
11384 backend if they exist. */
11387 {
11388 return
11395 }
11397 /* See if this can be simplified into a rotate first. If that
11398 is unsuccessful continue in the association code. */
11409 /* ~X ^ X is -1. */
11412 {
11416 }
11418 /* X ^ ~X is -1. */
11421 {
11425 }
11427 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11428 with a constant, and the two constants have no bits in common,
11429 we should treat this as a BIT_IOR_EXPR since this may produce more
11430 simplifications. */
11438 {
11441 }
11443 /* (X | Y) ^ X -> Y & ~ X*/
11446 {
11449 arg1);
11454 }
11456 /* (Y | X) ^ X -> Y & ~ X*/
11459 {
11462 arg1);
11467 }
11469 /* X ^ (X | Y) -> Y & ~ X*/
11472 {
11475 arg0);
11480 }
11482 /* X ^ (Y | X) -> Y & ~ X*/
11485 {
11488 arg0);
11493 }
11495 /* Convert ~X ^ ~Y to X ^ Y. */
11504 /* Convert ~X ^ C to X ^ ~C. */
11512 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11519 /* Fold (X & Y) ^ Y as ~X & Y. */
11522 {
11527 }
11528 /* Fold (X & Y) ^ X as ~Y & X. */
11532 {
11537 }
11538 /* Fold X ^ (X & Y) as X & ~Y. */
11541 {
11546 }
11547 /* Fold X ^ (Y & X) as ~Y & X. */
11551 {
11556 }
11558 /* See if this can be simplified into a rotate first. If that
11559 is unsuccessful continue in the association code. */
11570 /* ~X & X is always zero. */
11575 /* X & ~X is always zero. */
11580 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11584 {
11590 return
11594 }
11596 /* (X | Y) & Y is (X, Y). */
11600 /* (X | Y) & X is (Y, X). */
11605 /* X & (X | Y) is (Y, X). */
11610 /* X & (Y | X) is (Y, X). */
11616 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11620 {
11626 }
11627 /* Fold ~X & 1 as (X & 1) == 0. */
11630 {
11636 }
11638 /* Fold (X ^ Y) & Y as ~X & Y. */
11641 {
11646 }
11647 /* Fold (X ^ Y) & X as ~Y & X. */
11651 {
11656 }
11657 /* Fold X & (X ^ Y) as X & ~Y. */
11660 {
11665 }
11666 /* Fold X & (Y ^ X) as ~Y & X. */
11670 {
11675 }
11680 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11683 {
11684 unsigned int prec
11690 return
11692 }
11694 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11696 This results in more efficient code for machines without a NOR
11697 instruction. Combine will canonicalize to the first form
11698 which will allow use of NOR instructions provided by the
11699 backend if they exist. */
11702 {
11709 }
11711 /* If arg0 is derived from the address of an object or function, we may
11712 be able to fold this expression using the object or function's
11713 alignment. */
11715 {
11722 /* This works because modulus is a power of 2. If this weren't the
11723 case, we'd have to replace it by its greatest power-of-2
11724 divisor: modulus & -modulus. */
11727 }
11729 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11730 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11731 if the new mask might be further optimized. */
11740 {
11742 unsigned HOST_WIDE_INT mask
11752 {
11755 /* See if more bits can be proven as zero because of
11756 zero extension. */
11759 {
11764 {
11766 /* See if we can shorten the right shift. */
11769 }
11770 }
11774 /* For arithmetic shift if sign bit could be set, zerobits
11775 can contain actually sign bits, so no transformation is
11776 possible, unless MASK masks them all away. In that
11777 case the shift needs to be converted into logical shift. */
11780 {
11783 else
11785 }
11786 }
11788 /* ((X << 16) & 0xff00) is (X, 0). */
11795 {
11798 /* Only do the transformation if NEWMASK is some integer
11799 mode's mask. */
11806 {
11807 tree newmaskt;
11810 {
11816 }
11817 else
11822 }
11823 }
11824 }
11829 /* Don't touch a floating-point divide by zero unless the mode
11830 of the constant can represent infinity. */
11836 /* Optimize A / A to 1.0 if we don't care about
11837 NaNs or Infinities. Skip the transformation
11838 for non-real operands. */
11843 {
11847 }
11849 /* The complex version of the above A / A optimization. */
11852 {
11856 {
11858 /* omit_two_operands will call fold_convert for us. */
11860 }
11861 }
11863 /* (-A) / (-B) -> A / B */
11873 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11878 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11884 /* If ARG1 is a constant, we can convert this to a multiply by the
11885 reciprocal. This does not have the same rounding properties,
11886 so only do this if -freciprocal-math. We can actually
11887 always safely do it if ARG1 is a power of two, but it's hard to
11888 tell if it is or not in a portable manner. */
11890 {
11895 /* Find the reciprocal if optimizing and the result is exact. */
11897 {
11898 REAL_VALUE_TYPE r;
11901 {
11905 }
11906 }
11907 }
11908 /* Convert A/B/C to A/(B*C). */
11915 /* Convert A/(B/C) to (A/B)*C. */
11923 /* Convert C1/(X*C2) into (C1/C2)/X. */
11928 {
11934 }
11937 {
11941 /* Optimize sin(x)/cos(x) as tan(x). */
11947 {
11952 }
11954 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11960 {
11964 {
11969 }
11970 }
11972 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11973 NaNs or Infinities. */
11977 {
11984 {
11989 }
11990 }
11992 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11993 NaNs or Infinities. */
11997 {
12004 {
12008 {
12012 tmp);
12013 }
12014 }
12015 }
12017 /* Optimize pow(x,c)/x as pow(x,c-1). */
12021 {
12027 {
12029 REAL_VALUE_TYPE c;
12030 tree arg;
12036 }
12037 }
12039 /* Optimize a/root(b/c) into a*root(c/b). */
12041 {
12045 {
12054 }
12055 }
12057 /* Optimize x/expN(y) into x*expN(-y). */
12059 {
12066 }
12068 /* Optimize x/pow(y,z) into x*pow(y,-z). */
12072 {
12080 }
12081 }
12086 /* Simplify A / (B << N) where A and B are positive and B is
12087 a power of 2, to A >> (N + log2(B)). */
12092 {
12095 {
12102 WARN_STRICT_OVERFLOW_MISC);
12108 }
12109 }
12111 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
12112 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12118 /* Fall thru */
12127 /* X / -1 is -X. */
12134 /* Convert -A / -B to A / B when the type is signed and overflow is
12135 undefined. */
12139 {
12142 "when distributing negation across "
12144 WARN_STRICT_OVERFLOW_MISC);
12150 }
12154 {
12157 "when distributing negation across "
12159 WARN_STRICT_OVERFLOW_MISC);
12165 }
12167 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12168 operation, EXACT_DIV_EXPR.
12170 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12171 At one time others generated faster code, it's not clear if they do
12172 after the last round to changes to the DIV code in expmed.c. */
12181 {
12185 WARN_STRICT_OVERFLOW_MISC);
12187 }
12195 /* X % 1 is always zero, but be sure to preserve any side
12196 effects in X. */
12200 /* X % 0, return X % 0 unchanged so that we can get the
12201 proper warnings and errors. */
12205 /* 0 % X is always zero, but be sure to preserve any side
12206 effects in X. Place this after checking for X == 0. */
12210 /* X % -1 is zero. */
12217 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12218 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12223 {
12225 /* Also optimize A % (C << N) where C is a power of 2,
12226 to A & ((C << N) - 1). */
12231 {
12236 "occur when simplifying "
12238 WARN_STRICT_OVERFLOW_MISC);
12242 }
12243 }
12245 /* X % -C is the same as X % C. */
12252 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12259 /* X % -Y is the same as X % Y. */
12271 {
12275 WARN_STRICT_OVERFLOW_MISC);
12277 }
12288 /* Optimize -1 >> x for arithmetic right shifts. */
12292 /* ... fall through ... */
12295 shift:
12301 /* Since negative shift count is not well-defined,
12302 don't try to compute it in the compiler. */
12306 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12311 {
12315 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12316 being well defined. */
12318 {
12324 else
12326 }
12330 }
12332 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12333 into x & ((unsigned)-1 >> c) for unsigned types. */
12341 {
12344 tree lshift;
12345 tree arg00;
12348 {
12355 }
12356 }
12358 /* Rewrite an LROTATE_EXPR by a constant into an
12359 RROTATE_EXPR by a new constant. */
12361 {
12366 }
12368 /* If we have a rotate of a bit operation with the rotate count and
12369 the second operand of the bit operation both constant,
12370 permute the two operations. */
12382 /* Two consecutive rotates adding up to the precision of the
12383 type can be ignored. */
12394 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12395 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12396 if the latter can be further optimized. */
12401 {
12405 arg1);
12409 arg1);
12413 }
12441 /* Note that the operands of this must be ints
12442 and their values must be 0 or 1.
12443 ("true" is a fixed value perhaps depending on the language.) */
12444 /* If first arg is constant zero, return it. */
12448 /* If either arg is constant true, drop it. */
12452 /* Preserve sequence points. */
12455 /* If second arg is constant zero, result is zero, but first arg
12456 must be evaluated. */
12459 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12460 case will be handled here. */
12464 /* !X && X is always false. */
12468 /* X && !X is always false. */
12473 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12474 means A >= Y && A != MAX, but in this case we know that
12475 A < X <= MAX. */
12479 {
12487 }
12489 truth_andor:
12490 /* We only do these simplifications if we are optimizing. */
12494 /* Check for things like (A || B) && (A || C). We can convert this
12495 to A || (B && C). Note that either operator can be any of the four
12496 truth and/or operations and the transformation will still be
12497 valid. Also note that we only care about order for the
12498 ANDIF and ORIF operators. If B contains side effects, this
12499 might change the truth-value of A. */
12506 {
12526 /* This case if tricky because we must either have commutative
12527 operators or else A10 must not have side-effects. */
12533 a01);
12534 }
12536 /* See if we can build a range comparison. */
12540 /* Check for the possibility of merging component references. If our
12541 lhs is another similar operation, try to merge its rhs with our
12542 rhs. Then try to merge our lhs and rhs. */
12554 /* Note that the operands of this must be ints
12555 and their values must be 0 or true.
12556 ("true" is a fixed value perhaps depending on the language.) */
12557 /* If first arg is constant true, return it. */
12561 /* If either arg is constant zero, drop it. */
12565 /* Preserve sequence points. */
12568 /* If second arg is constant true, result is true, but we must
12569 evaluate first arg. */
12572 /* Likewise for first arg, but note this only occurs here for
12573 TRUTH_OR_EXPR. */
12577 /* !X || X is always true. */
12581 /* X || !X is always true. */
12589 /* If the second arg is constant zero, drop it. */
12592 /* If the second arg is constant true, this is a logical inversion. */
12594 {
12595 /* Only call invert_truthvalue if operand is a truth value. */
12598 else
12601 }
12602 /* Identical arguments cancel to zero. */
12606 /* !X ^ X is always true. */
12611 /* X ^ !X is always true. */
12624 /* bool_var != 0 becomes bool_var. */
12629 /* bool_var == 1 becomes bool_var. */
12634 /* bool_var != 1 becomes !bool_var. */
12640 /* bool_var == 0 becomes !bool_var. */
12646 /* !exp != 0 becomes !exp */
12651 /* If this is an equality comparison of the address of two non-weak,
12652 unaliased symbols neither of which are extern (since we do not
12653 have access to attributes for externs), then we know the result. */
12666 {
12667 /* We know that we're looking at the address of two
12668 non-weak, unaliased, static _DECL nodes.
12670 It is both wasteful and incorrect to call operand_equal_p
12671 to compare the two ADDR_EXPR nodes. It is wasteful in that
12672 all we need to do is test pointer equality for the arguments
12673 to the two ADDR_EXPR nodes. It is incorrect to use
12674 operand_equal_p as that function is NOT equivalent to a
12675 C equality test. It can in fact return false for two
12676 objects which would test as equal using the C equality
12677 operator. */
12681 type);
12682 }
12684 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12685 a MINUS_EXPR of a constant, we can convert it into a comparison with
12686 a revised constant as long as no overflow occurs. */
12694 arg1),
12699 /* Similarly for a NEGATE_EXPR. */
12707 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12715 arg1),
12718 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12725 {
12729 val,
12733 }
12735 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12740 {
12742 code == NE_EXPR
12745 }
12747 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12748 for !=. Don't do this for ordered comparisons due to overflow. */
12754 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12759 /* If this is an EQ or NE comparison with zero and ARG0 is
12760 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12761 two operations, but the latter can be done in one less insn
12762 on machines that have only two-operand insns or on which a
12763 constant cannot be the first operand. */
12766 {
12771 {
12778 arg1);
12779 }
12782 {
12789 arg1);
12790 }
12791 }
12793 /* If this is an NE or EQ comparison of zero against the result of a
12794 signed MOD operation whose second operand is a power of 2, make
12795 the MOD operation unsigned since it is simpler and equivalent. */
12803 {
12813 }
12815 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12816 C1 is a valid shift constant, and C2 is a power of two, i.e.
12817 a single bit. */
12821 == INTEGER_CST
12824 {
12829 /* Check for a valid shift count. */
12832 {
12836 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12837 can be rewritten as (X & (C2 << C1)) != 0. */
12839 {
12843 }
12844 /* Otherwise, for signed (arithmetic) shifts,
12845 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12846 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12850 /* Otherwise, of unsigned (logical) shifts,
12851 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12852 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12853 else
12857 arg000);
12858 }
12859 }
12861 /* If this is an NE comparison of zero with an AND of one, remove the
12862 comparison since the AND will give the correct value. */
12869 /* If we have (A & C) == C where C is a power of 2, convert this into
12870 (A & C) != 0. Similarly for NE_EXPR. */
12876 integer_zero_node));
12878 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12879 bit, then fold the expression into A < 0 or A >= 0. */
12884 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12885 Similarly for NE_EXPR. */
12889 {
12898 }
12900 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12901 Similarly for NE_EXPR. */
12905 {
12912 }
12914 /* If this is a comparison of a field, we may be able to simplify it. */
12917 /* Handle the constant case even without -O
12918 to make sure the warnings are given. */
12920 {
12924 }
12926 /* Optimize comparisons of strlen vs zero to a compare of the
12927 first character of the string vs zero. To wit,
12928 strlen(ptr) == 0 => *ptr == 0
12929 strlen(ptr) != 0 => *ptr != 0
12930 Other cases should reduce to one of these two (or a constant)
12931 due to the return value of strlen being unsigned. */
12934 {
12942 {
12947 }
12948 }
12950 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12951 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12955 {
12962 {
12964 {
12967 }
12970 }
12971 }
12973 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12979 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12984 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12991 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12999 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
13000 (X & C) == 0 when C is a single bit. */
13005 {
13011 }
13013 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
13014 constant C is a power of two, i.e. a single bit. */
13021 {
13025 }
13027 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
13028 when is C is a power of two, i.e. a single bit. */
13035 {
13041 }
13045 {
13048 }
13050 /* Fold -X op -Y as X op Y, where op is eq/ne. */
13057 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
13060 {
13073 arg01),
13082 arg01),
13091 arg00),
13100 arg00),
13102 }
13106 {
13113 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
13114 operand_equal_p guarantees no side-effects so we don't need
13115 to use omit_one_operand on Z. */
13125 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13133 arg10);
13134 }
13136 /* Attempt to simplify equality/inequality comparisons of complex
13137 values. Only lower the comparison if the result is known or
13138 can be simplified to a single scalar comparison. */
13143 {
13148 {
13151 }
13152 else
13153 {
13156 }
13159 {
13162 }
13163 else
13164 {
13167 }
13171 {
13173 {
13178 }
13179 else
13180 {
13185 }
13186 }
13190 {
13192 {
13197 }
13198 else
13199 {
13204 }
13205 }
13206 }
13218 /* Transform comparisons of the form X +- C CMP X. */
13225 {
13232 else
13235 /* (X - c) > X becomes false. */
13239 {
13243 "occur when assuming that (X - c) > X "
13245 WARN_STRICT_OVERFLOW_ALL);
13247 }
13249 /* Likewise (X + c) < X becomes false. */
13253 {
13257 "occur when assuming that "
13259 WARN_STRICT_OVERFLOW_ALL);
13261 }
13263 /* Convert (X - c) <= X to true. */
13268 {
13272 "occur when assuming that "
13274 WARN_STRICT_OVERFLOW_ALL);
13276 }
13278 /* Convert (X + c) >= X to true. */
13283 {
13287 "occur when assuming that "
13289 WARN_STRICT_OVERFLOW_ALL);
13291 }
13294 {
13295 /* Convert X + c > X and X - c < X to true for integers. */
13299 {
13302 "not occur when assuming that "
13304 WARN_STRICT_OVERFLOW_ALL);
13306 }
13311 {
13314 "not occur when assuming that "
13316 WARN_STRICT_OVERFLOW_ALL);
13318 }
13320 /* Convert X + c <= X and X - c >= X to false for integers. */
13324 {
13327 "not occur when assuming that "
13329 WARN_STRICT_OVERFLOW_ALL);
13331 }
13336 {
13339 "not occur when assuming that "
13341 WARN_STRICT_OVERFLOW_ALL);
13343 }
13344 }
13345 }
13347 /* Comparisons with the highest or lowest possible integer of
13348 the specified precision will have known values. */
13349 {
13356 {
13357 HOST_WIDE_INT signed_max_hi;
13362 {
13369 {
13373 }
13374 else
13375 {
13379 }
13380 }
13381 else
13382 {
13391 {
13394 }
13395 else
13396 {
13399 }
13400 }
13405 {
13418 /* The GE_EXPR and LT_EXPR cases above are not normally
13419 reached because of previous transformations. */
13423 }
13425 == max_hi
13428 {
13435 arg1);
13441 arg0),
13442 arg1);
13445 }
13447 == min_hi
13450 {
13465 }
13467 == min_hi
13470 {
13476 arg1);
13481 arg0),
13482 arg1);
13485 }
13490 /* We will flip the signedness of the comparison operator
13491 associated with the mode of arg1, so the sign bit is
13492 specified by this mode. Check that arg1 is the signed
13493 max associated with this sign bit. */
13495 /* signed_type does not work on pointer types. */
13497 {
13498 /* The following case also applies to X < signed_max+1
13499 and X >= signed_max+1 because previous transformations. */
13501 {
13502 tree st;
13508 }
13509 }
13510 }
13511 }
13513 /* If we are comparing an ABS_EXPR with a constant, we can
13514 convert all the cases into explicit comparisons, but they may
13515 well not be faster than doing the ABS and one comparison.
13516 But ABS (X) <= C is a range comparison, which becomes a subtraction
13517 and a comparison, and is probably faster. */
13531 /* Convert ABS_EXPR<x> >= 0 to true. */
13538 {
13541 "when simplifying comparison of "
13543 WARN_STRICT_OVERFLOW_CONDITIONAL);
13545 }
13547 /* Convert ABS_EXPR<x> < 0 to false. */
13552 {
13555 "when simplifying comparison of "
13557 WARN_STRICT_OVERFLOW_CONDITIONAL);
13559 }
13561 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13562 and similarly for >= into !=. */
13567 {
13573 }
13580 {
13589 }
13602 {
13606 }
13608 /* If the first operand is NaN, the result is constant. */
13612 {
13614 ? integer_zero_node
13617 }
13619 /* If the second operand is NaN, the result is constant. */
13623 {
13625 ? integer_zero_node
13628 }
13630 /* Simplify unordered comparison of something with itself. */
13636 && !flag_trapping_math
13640 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13641 {
13653 }
13658 /* When pedantic, a compound expression can be neither an lvalue
13659 nor an integer constant expression. */
13662 /* Don't let (0, 0) be null pointer constant. */
13676 /* An ASSERT_EXPR should never be passed to fold_binary. */
13682 fold_binary_exit:
13685 }
13687 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13688 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13689 of GOTO_EXPR. */
13691 static tree
13693 {
13695 {
13702 /* ... fall through ... */
13706 }
13707 }
13709 /* Return whether the sub-tree ST contains a label which is accessible from
13710 outside the sub-tree. */
13712 static bool
13714 {
13715 return
13717 }
13719 /* Fold a ternary expression of code CODE and type TYPE with operands
13720 OP0, OP1, and OP2. Return the folded expression if folding is
13721 successful. Otherwise, return NULL_TREE. */
13723 tree
13726 {
13727 tree tem;
13734 /* Strip any conversions that don't change the mode. This is safe
13735 for every expression, except for a comparison expression because
13736 its signedness is derived from its operands. So, in the latter
13737 case, only strip conversions that don't change the signedness.
13739 Note that this is done as an internal manipulation within the
13740 constant folder, in order to find the simplest representation of
13741 the arguments so that their form can be studied. In any cases,
13742 the appropriate type conversions should be put back in the tree
13743 that will get out of the constant folder. */
13745 {
13748 }
13751 {
13754 }
13757 {
13761 {
13767 }
13771 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13772 so all simple results must be passed through pedantic_non_lvalue. */
13774 {
13777 /* Only optimize constant conditions when the selected branch
13778 has the same type as the COND_EXPR. This avoids optimizing
13779 away "c ? x : throw", where the throw has a void type.
13780 Avoid throwing away that operand which contains label. */
13787 }
13791 /* If we have A op B ? A : C, we may be able to convert this to a
13792 simpler expression, depending on the operation and the values
13793 of B and C. Signed zeros prevent all of these transformations,
13794 for reasons given above each one.
13796 Also try swapping the arguments and inverting the conditional. */
13801 {
13805 }
13809 op2,
13812 {
13815 {
13819 }
13820 }
13822 /* If the second operand is simpler than the third, swap them
13823 since that produces better jump optimization results. */
13826 {
13827 /* See if this can be inverted. If it can't, possibly because
13828 it was a floating-point inequality comparison, don't do
13829 anything. */
13833 }
13835 /* Convert A ? 1 : 0 to simply A. */
13838 /* If we try to convert OP0 to our type, the
13839 call to fold will try to move the conversion inside
13840 a COND, which will recurse. In that case, the COND_EXPR
13841 is probably the best choice, so leave it alone. */
13845 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13846 over COND_EXPR in cases such as floating point comparisons. */
13853 arg0)));
13855 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13860 {
13861 /* sign_bit_p only checks ARG1 bits within A's precision.
13862 If <sign bit of A> has wider type than A, bits outside
13863 of A's precision in <sign bit of A> need to be checked.
13864 If they are all 0, this optimization needs to be done
13865 in unsigned A's type, if they are all 1 in signed A's type,
13866 otherwise this can't be done. */
13871 {
13873 HOST_WIDE_INT mask_hi;
13875 tree tem_type;
13883 {
13887 }
13888 else
13889 {
13893 }
13895 {
13899 }
13900 else
13906 {
13909 }
13912 {
13915 }
13916 else
13918 }
13921 return
13927 arg1)));
13928 }
13930 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13931 already handled above. */
13936 {
13945 }
13947 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13948 is probably obsolete because the first operand should be a
13949 truth value (that's why we have the two cases above), but let's
13950 leave it in until we can confirm this for all front-ends. */
13962 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13968 arg1);
13970 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13974 {
13975 /* Only perform transformation if ARG0 is easily inverted. */
13980 arg1);
13981 }
13983 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13987 {
13988 /* Only perform transformation if ARG0 is easily inverted. */
13993 op2);
13994 }
13996 /* Convert A ? 1 : B into A || B if A and B are truth values. */
14002 op2);
14007 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
14008 of fold_ternary on them. */
14015 {
14024 {
14029 else
14030 {
14032 tree value;
14036 }
14041 else
14043 }
14044 }
14046 /* A bit-field-ref that referenced the full argument can be stripped. */
14057 }
14059 /* Perform constant folding and related simplification of EXPR.
14060 The related simplifications include x*1 => x, x*0 => 0, etc.,
14061 and application of the associative law.
14062 NOP_EXPR conversions may be removed freely (as long as we
14063 are careful not to change the type of the overall expression).
14064 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14065 but we can constant-fold them if they have constant operands. */
14067 #ifdef ENABLE_FOLD_CHECKING
14068 # define fold(x) fold_1 (x)
14070 static
14071 #endif
14072 tree
14074 {
14078 tree tem;
14081 /* Return right away if a constant. */
14085 /* CALL_EXPR-like objects with variable numbers of operands are
14086 treated specially. */
14088 {
14090 {
14093 }
14095 }
14098 {
14103 {
14121 }
14122 }
14125 {
14127 {
14134 {
14139 /* Find a matching index by means of a binary search. */
14141 {
14157 else
14159 }
14160 }
14163 }
14171 }
14173 #ifdef ENABLE_FOLD_CHECKING
14174 #undef fold
14180 /* When --enable-checking=fold, compute a digest of expr before
14181 and after actual fold call to see if fold did not accidentally
14182 change original expr. */
14184 tree
14186 {
14187 tree ret;
14190 htab_t ht;
14209 }
14211 void
14213 {
14216 htab_t ht;
14226 }
14228 static void
14230 {
14232 }
14234 static void
14236 {
14242 recursive_label:
14256 {
14257 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14261 }
14268 {
14269 /* Allow these fields to be modified. */
14270 tree tmp;
14278 {
14281 }
14282 }
14291 {
14294 {
14308 }
14312 {
14325 }
14342 {
14348 }
14353 {
14357 }
14368 {
14371 }
14381 }
14382 }
14384 /* Helper function for outputting the checksum of a tree T. When
14385 debugging with gdb, you can "define mynext" to be "next" followed
14386 by "call debug_fold_checksum (op0)", then just trace down till the
14387 outputs differ. */
14389 void
14391 {
14406 }
14408 #endif
14410 /* Fold a unary tree expression with code CODE of type TYPE with an
14411 operand OP0. LOC is the location of the resulting expression.
14412 Return a folded expression if successful. Otherwise, return a tree
14413 expression with code CODE of type TYPE with an operand OP0. */
14415 tree
14418 {
14419 tree tem;
14420 #ifdef ENABLE_FOLD_CHECKING
14423 htab_t ht;
14430 #endif
14434 {
14437 }
14439 #ifdef ENABLE_FOLD_CHECKING
14447 #endif
14449 }
14451 /* Fold a binary tree expression with code CODE of type TYPE with
14452 operands OP0 and OP1. LOC is the location of the resulting
14453 expression. Return a folded expression if successful. Otherwise,
14454 return a tree expression with code CODE of type TYPE with operands
14455 OP0 and OP1. */
14457 tree
14460 MEM_STAT_DECL)
14461 {
14462 tree tem;
14463 #ifdef ENABLE_FOLD_CHECKING
14469 htab_t ht;
14481 #endif
14485 {
14488 }
14490 #ifdef ENABLE_FOLD_CHECKING
14506 #endif
14508 }
14510 /* Fold a ternary tree expression with code CODE of type TYPE with
14511 operands OP0, OP1, and OP2. Return a folded expression if
14512 successful. Otherwise, return a tree expression with code CODE of
14513 type TYPE with operands OP0, OP1, and OP2. */
14515 tree
14518 {
14519 tree tem;
14520 #ifdef ENABLE_FOLD_CHECKING
14528 htab_t ht;
14545 #endif
14550 {
14553 }
14555 #ifdef ENABLE_FOLD_CHECKING
14579 #endif
14581 }
14583 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14584 arguments in ARGARRAY, and a null static chain.
14585 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14586 of type TYPE from the given operands as constructed by build_call_array. */
14588 tree
14591 {
14592 tree tem;
14593 #ifdef ENABLE_FOLD_CHECKING
14599 htab_t ht;
14613 #endif
14617 #ifdef ENABLE_FOLD_CHECKING
14634 #endif
14636 }
14638 /* Perform constant folding and related simplification of initializer
14639 expression EXPR. These behave identically to "fold_buildN" but ignore
14640 potential run-time traps and exceptions that fold must preserve. */
14642 #define START_FOLD_INIT \
14643 int saved_signaling_nans = flag_signaling_nans;\
14644 int saved_trapping_math = flag_trapping_math;\
14645 int saved_rounding_math = flag_rounding_math;\
14646 int saved_trapv = flag_trapv;\
14647 int saved_folding_initializer = folding_initializer;\
14648 flag_signaling_nans = 0;\
14649 flag_trapping_math = 0;\
14650 flag_rounding_math = 0;\
14651 flag_trapv = 0;\
14652 folding_initializer = 1;
14654 #define END_FOLD_INIT \
14655 flag_signaling_nans = saved_signaling_nans;\
14656 flag_trapping_math = saved_trapping_math;\
14657 flag_rounding_math = saved_rounding_math;\
14658 flag_trapv = saved_trapv;\
14659 folding_initializer = saved_folding_initializer;
14661 tree
14664 {
14665 tree result;
14666 START_FOLD_INIT;
14670 END_FOLD_INIT;
14672 }
14674 tree
14677 {
14678 tree result;
14679 START_FOLD_INIT;
14683 END_FOLD_INIT;
14685 }
14687 tree
14690 {
14691 tree result;
14692 START_FOLD_INIT;
14696 END_FOLD_INIT;
14698 }
14700 tree
14703 {
14704 tree result;
14705 START_FOLD_INIT;
14709 END_FOLD_INIT;
14711 }
14713 #undef START_FOLD_INIT
14714 #undef END_FOLD_INIT
14716 /* Determine if first argument is a multiple of second argument. Return 0 if
14717 it is not, or we cannot easily determined it to be.
14719 An example of the sort of thing we care about (at this point; this routine
14720 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14721 fold cases do now) is discovering that
14723 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14725 is a multiple of
14727 SAVE_EXPR (J * 8)
14729 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14731 This code also handles discovering that
14733 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14735 is a multiple of 8 so we don't have to worry about dealing with a
14736 possible remainder.
14738 Note that we *look* inside a SAVE_EXPR only to determine how it was
14739 calculated; it is not safe for fold to do much of anything else with the
14740 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14741 at run time. For example, the latter example above *cannot* be implemented
14742 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14743 evaluation time of the original SAVE_EXPR is not necessarily the same at
14744 the time the new expression is evaluated. The only optimization of this
14745 sort that would be valid is changing
14747 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14749 divided by 8 to
14751 SAVE_EXPR (I) * SAVE_EXPR (J)
14753 (where the same SAVE_EXPR (J) is used in the original and the
14754 transformed version). */
14756 int
14758 {
14766 {
14768 /* Bitwise and provides a power of two multiple. If the mask is
14769 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14772 /* FALLTHRU */
14785 {
14789 /* const_binop may not detect overflow correctly,
14790 so check for it explicitly here. */
14796 size_one_node,
14800 }
14804 /* Can't handle conversions from non-integral or wider integral type. */
14810 /* .. fall through ... */
14827 }
14828 }
14830 /* Return true if CODE or TYPE is known to be non-negative. */
14832 static bool
14834 {
14837 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14838 have a signed:1 type (where the value is -1 and 0). */
14841 }
14843 /* Return true if (CODE OP0) is known to be non-negative. If the return
14844 value is based on the assumption that signed overflow is undefined,
14845 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14846 *STRICT_OVERFLOW_P. */
14848 bool
14851 {
14856 {
14858 /* We can't return 1 if flag_wrapv is set because
14859 ABS_EXPR<INT_MIN> = INT_MIN. */
14863 {
14866 }
14873 strict_overflow_p);
14876 {
14881 {
14884 strict_overflow_p);
14886 {
14890 strict_overflow_p);
14891 }
14892 }
14894 {
14897 strict_overflow_p);
14901 }
14902 }
14907 }
14909 /* We don't know sign of `t', so be conservative and return false. */
14911 }
14913 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14914 value is based on the assumption that signed overflow is undefined,
14915 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14916 *STRICT_OVERFLOW_P. */
14918 bool
14921 {
14926 {
14931 strict_overflow_p)
14933 strict_overflow_p));
14935 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14936 both unsigned and at least 2 bits shorter than the result. */
14940 {
14945 {
14949 }
14950 }
14955 {
14956 /* x * x for floating point x is always non-negative. */
14960 strict_overflow_p)
14962 strict_overflow_p));
14963 }
14965 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14966 both unsigned and their total bits is shorter than the result. */
14970 {
14989 {
14999 }
15000 }
15006 strict_overflow_p)
15008 strict_overflow_p));
15019 strict_overflow_p)
15021 strict_overflow_p));
15028 strict_overflow_p);
15031 }
15033 /* We don't know sign of `t', so be conservative and return false. */
15035 }
15037 /* Return true if T is known to be non-negative. If the return
15038 value is based on the assumption that signed overflow is undefined,
15039 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15040 *STRICT_OVERFLOW_P. */
15042 bool
15044 {
15049 {
15061 strict_overflow_p)
15063 strict_overflow_p));
15067 }
15068 /* We don't know sign of `t', so be conservative and return false. */
15070 }
15072 /* Return true if T is known to be non-negative. If the return
15073 value is based on the assumption that signed overflow is undefined,
15074 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15075 *STRICT_OVERFLOW_P. */
15077 bool
15080 {
15083 {
15101 /* Always true. */
15105 /* sqrt(-0.0) is -0.0. */
15109 strict_overflow_p);
15142 /* True if the 1st argument is nonnegative. */
15144 strict_overflow_p);
15147 /* True if the 1st OR 2nd arguments are nonnegative. */
15149 strict_overflow_p)
15151 strict_overflow_p)));
15154 /* True if the 1st AND 2nd arguments are nonnegative. */
15156 strict_overflow_p)
15158 strict_overflow_p)));
15161 /* True if the 2nd argument is nonnegative. */
15163 strict_overflow_p);
15166 /* True if the 1st argument is nonnegative or the second
15167 argument is an even integer. */
15172 strict_overflow_p);
15175 /* True if the 1st argument is nonnegative or the second
15176 argument is an even integer valued real. */
15178 {
15179 REAL_VALUE_TYPE c;
15180 HOST_WIDE_INT n;
15185 {
15186 REAL_VALUE_TYPE cint;
15191 }
15192 }
15194 strict_overflow_p);
15198 }
15200 type);
15201 }
15203 /* Return true if T is known to be non-negative. If the return
15204 value is based on the assumption that signed overflow is undefined,
15205 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15206 *STRICT_OVERFLOW_P. */
15208 bool
15210 {
15216 {
15218 {
15222 /* If the initializer is non-void, then it's a normal expression
15223 that will be assigned to the slot. */
15227 /* Otherwise, the initializer sets the slot in some way. One common
15228 way is an assignment statement at the end of the initializer. */
15230 {
15238 else
15240 }
15244 strict_overflow_p);
15247 }
15250 {
15256 arg0,
15257 arg1,
15258 strict_overflow_p);
15259 }
15263 strict_overflow_p);
15266 strict_overflow_p);
15269 strict_overflow_p);
15274 }
15276 /* We don't know sign of `t', so be conservative and return false. */
15278 }
15280 /* Return true if T is known to be non-negative. If the return
15281 value is based on the assumption that signed overflow is undefined,
15282 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15283 *STRICT_OVERFLOW_P. */
15285 bool
15287 {
15294 {
15301 strict_overflow_p);
15307 strict_overflow_p);
15316 }
15319 {
15327 strict_overflow_p);
15332 strict_overflow_p);
15345 }
15346 }
15348 /* Return true if `t' is known to be non-negative. Handle warnings
15349 about undefined signed overflow. */
15351 bool
15353 {
15360 "determining that expression is always "
15362 WARN_STRICT_OVERFLOW_MISC);
15364 }
15367 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15368 For floating point we further ensure that T is not denormal.
15369 Similar logic is present in nonzero_address in rtlanal.h.
15371 If the return value is based on the assumption that signed overflow
15372 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15373 change *STRICT_OVERFLOW_P. */
15375 bool
15378 {
15380 {
15383 strict_overflow_p);
15386 {
15392 strict_overflow_p));
15393 }
15398 strict_overflow_p);
15402 }
15405 }
15407 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15408 For floating point we further ensure that T is not denormal.
15409 Similar logic is present in nonzero_address in rtlanal.h.
15411 If the return value is based on the assumption that signed overflow
15412 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15413 change *STRICT_OVERFLOW_P. */
15415 bool
15417 tree type,
15418 tree op0,
15420 {
15423 {
15427 {
15428 /* With the presence of negative values it is hard
15429 to say something. */
15436 /* One of operands must be positive and the other non-negative. */
15437 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15438 overflows, on a twos-complement machine the sum of two
15439 nonnegative numbers can never be zero. */
15441 strict_overflow_p)
15443 strict_overflow_p));
15444 }
15449 {
15451 strict_overflow_p)
15453 strict_overflow_p))
15454 {
15457 }
15458 }
15467 {
15470 }
15477 {
15481 /* When both operands are nonzero, then MAX must be too. */
15483 strict_overflow_p))
15486 /* MAX where operand 0 is positive is positive. */
15488 strict_overflow_p);
15489 }
15490 /* MAX where operand 1 is positive is positive. */
15495 {
15499 }
15504 strict_overflow_p)
15506 strict_overflow_p));
15510 }
15513 }
15515 /* Return true when T is an address and is known to be nonzero.
15516 For floating point we further ensure that T is not denormal.
15517 Similar logic is present in nonzero_address in rtlanal.h.
15519 If the return value is based on the assumption that signed overflow
15520 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15521 change *STRICT_OVERFLOW_P. */
15523 bool
15525 {
15528 {
15533 {
15539 /* Weak declarations may link to NULL. Other things may also be NULL
15540 so protect with -fdelete-null-pointer-checks; but not variables
15541 allocated on the stack. */
15543 && (flag_delete_null_pointer_checks
15547 /* Constants are never weak. */
15552 }
15560 {
15564 }
15569 }
15571 }
15573 /* Return true when T is an address and is known to be nonzero.
15574 For floating point we further ensure that T is not denormal.
15575 Similar logic is present in nonzero_address in rtlanal.h.
15577 If the return value is based on the assumption that signed overflow
15578 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15579 change *STRICT_OVERFLOW_P. */
15581 bool
15583 {
15587 /* Doing something useful for floating point would need more work. */
15593 {
15596 strict_overflow_p);
15602 strict_overflow_p);
15610 }
15613 {
15616 strict_overflow_p);
15624 strict_overflow_p);
15639 strict_overflow_p);
15643 strict_overflow_p);
15650 }
15652 }
15654 /* Return true when T is an address and is known to be nonzero.
15655 Handle warnings about undefined signed overflow. */
15657 bool
15659 {
15666 "determining that expression is always "
15668 WARN_STRICT_OVERFLOW_MISC);
15670 }
15672 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15673 attempt to fold the expression to a constant without modifying TYPE,
15674 OP0 or OP1.
15676 If the expression could be simplified to a constant, then return
15677 the constant. If the expression would not be simplified to a
15678 constant, then return NULL_TREE. */
15680 tree
15682 {
15685 }
15687 /* Given the components of a unary expression CODE, TYPE and OP0,
15688 attempt to fold the expression to a constant without modifying
15689 TYPE or OP0.
15691 If the expression could be simplified to a constant, then return
15692 the constant. If the expression would not be simplified to a
15693 constant, then return NULL_TREE. */
15695 tree
15697 {
15700 }
15702 /* If EXP represents referencing an element in a constant string
15703 (either via pointer arithmetic or array indexing), return the
15704 tree representing the value accessed, otherwise return NULL. */
15706 tree
15708 {
15712 {
15714 tree index;
15715 tree string;
15720 else
15721 {
15725 /* Optimize the special-case of a zero lower bound.
15727 We convert the low_bound to sizetype to avoid some problems
15728 with constant folding. (E.g. suppose the lower bound is 1,
15729 and its mode is QI. Without the conversion,l (ARRAY
15730 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15731 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15737 }
15750 }
15752 }
15754 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15755 an integer constant, real, or fixed-point constant.
15757 TYPE is the type of the result. */
15759 static tree
15761 {
15765 {
15767 {
15769 HOST_WIDE_INT high;
15777 }
15784 {
15785 FIXED_VALUE_TYPE f;
15790 /* Propagate overflow flags. */
15794 }
15798 }
15801 }
15803 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15804 an integer constant or real constant.
15806 TYPE is the type of the result. */
15808 tree
15810 {
15814 {
15816 /* If the value is unsigned, then the absolute value is
15817 the same as the ordinary value. */
15820 /* Similarly, if the value is non-negative. */
15823 /* If the value is negative, then the absolute value is
15824 its negation. */
15825 else
15826 {
15828 HOST_WIDE_INT high;
15834 }
15840 else
15846 }
15849 }
15851 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15852 constant. TYPE is the type of the result. */
15854 static tree
15856 {
15866 }
15868 /* Given CODE, a relational operator, the target type, TYPE and two
15869 constant operands OP0 and OP1, return the result of the
15870 relational operation. If the result is not a compile time
15871 constant, then return NULL_TREE. */
15873 static tree
15875 {
15878 /* From here on, the only cases we handle are when the result is
15879 known to be a constant. */
15882 {
15886 /* Handle the cases where either operand is a NaN. */
15888 {
15890 {
15918 }
15921 }
15924 }
15927 {
15931 }
15933 /* Handle equality/inequality of complex constants. */
15935 {
15946 else
15948 }
15950 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15952 To compute GT, swap the arguments and do LT.
15953 To compute GE, do LT and invert the result.
15954 To compute LE, swap the arguments, do LT and invert the result.
15955 To compute NE, do EQ and invert the result.
15957 Therefore, the code below must handle only EQ and LT. */
15960 {
15965 }
15967 /* Note that it is safe to invert for real values here because we
15968 have already handled the one case that it matters. */
15972 {
15975 }
15977 /* Compute a result for LT or EQ if args permit;
15978 Otherwise return T. */
15980 {
15985 else
15987 }
15988 else
15994 }
15996 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15997 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15998 itself. */
16000 tree
16002 {
16003 /* If the expression does not have side effects then we don't have to wrap
16004 it with a cleanup point expression. */
16008 /* If the expression is a return, check to see if the expression inside the
16009 return has no side effects or the right hand side of the modify expression
16010 inside the return. If either don't have side effects set we don't need to
16011 wrap the expression in a cleanup point expression. Note we don't check the
16012 left hand side of the modify because it should always be a return decl. */
16014 {
16021 }
16024 }
16026 /* Given a pointer value OP0 and a type TYPE, return a simplified version
16027 of an indirection through OP0, or NULL_TREE if no simplification is
16028 possible. */
16030 tree
16032 {
16034 tree subtype;
16042 {
16045 /* *&CONST_DECL -> to the value of the const decl. */
16048 /* *&p => p; make sure to handle *&"str"[cst] here. */
16050 {
16054 else
16056 }
16057 /* *(foo *)&fooarray => fooarray[0] */
16060 {
16068 }
16069 /* *(foo *)&complexfoo => __real__ complexfoo */
16073 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16076 {
16080 }
16081 }
16083 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16086 {
16089 tree op00type;
16096 {
16108 }
16109 }
16112 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16115 {
16118 tree op00type;
16125 {
16130 }
16131 }
16133 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16136 {
16137 tree type_domain;
16146 }
16149 }
16151 /* Builds an expression for an indirection through T, simplifying some
16152 cases. */
16154 tree
16156 {
16166 }
16168 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16170 tree
16172 {
16177 else
16179 }
16181 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16182 whose result is ignored. The type of the returned tree need not be
16183 the same as the original expression. */
16185 tree
16187 {
16193 {
16204 else
16210 {
16226 }
16231 }
16232 }
16234 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
16235 This can only be applied to objects of a sizetype. */
16237 tree
16239 {
16246 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16247 have to do anything. Only do this when we are not given a const,
16248 because in that case, this check is more expensive than just
16249 doing it. */
16251 {
16256 }
16258 /* If divisor is a power of two, simplify this to bit manipulation. */
16260 {
16262 {
16275 {
16276 high++;
16279 }
16283 }
16284 else
16285 {
16286 tree t;
16292 }
16293 }
16294 else
16295 {
16300 }
16303 }
16305 /* Likewise, but round down. */
16307 tree
16309 {
16316 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16317 have to do anything. Only do this when we are not given a const,
16318 because in that case, this check is more expensive than just
16319 doing it. */
16321 {
16326 }
16328 /* If divisor is a power of two, simplify this to bit manipulation. */
16330 {
16331 tree t;
16335 }
16336 else
16337 {
16342 }
16345 }
16347 /* Returns the pointer to the base of the object addressed by EXP and
16348 extracts the information about the offset of the access, storing it
16349 to PBITPOS and POFFSET. */
16351 static tree
16354 {
16355 tree core;
16358 HOST_WIDE_INT bitsize;
16362 {
16367 }
16368 else
16369 {
16373 }
16376 }
16378 /* Returns true if addresses of E1 and E2 differ by a constant, false
16379 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16381 bool
16383 {
16397 {
16407 }
16409 {
16410 /* If only one of the offsets is non-constant, the difference cannot
16411 be a constant. */
16413 }
16414 else
16419 }
16421 /* Simplify the floating point expression EXP when the sign of the
16422 result is not significant. Return NULL_TREE if no simplification
16423 is possible. */
16425 tree
16427 {
16432 {
16468 {
16471 {
16473 /* Strip copysign function call, return the 1st argument. */
16479 /* Strip sign ops from the argument of "odd" math functions. */
16481 {
16485 }
16487 }
16488 }
16493 }
16495 }