| blob | 03598a59a6f0ca3b2e46688ba4a970c734d56741 |
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, 2010
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 /* Similar, if either does not have a type (like a released SSA name),
3174 they aren't equal. */
3178 /* Check equality of integer constants before bailing out due to
3179 precision differences. */
3183 /* If both types don't have the same signedness, then we can't consider
3184 them equal. We must check this before the STRIP_NOPS calls
3185 because they may change the signedness of the arguments. As pointers
3186 strictly don't have a signedness, require either two pointers or
3187 two non-pointers as well. */
3192 /* We cannot consider pointers to different address space equal. */
3198 /* If both types don't have the same precision, then it is not safe
3199 to strip NOPs. */
3206 /* In case both args are comparisons but with different comparison
3207 code, try to swap the comparison operands of one arg to produce
3208 a match and compare that variant. */
3212 {
3220 }
3223 /* This is needed for conversions and for COMPONENT_REF.
3224 Might as well play it safe and always test this. */
3230 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3231 We don't care about side effects in that case because the SAVE_EXPR
3232 takes care of that for us. In all other cases, two expressions are
3233 equal if they have no side effects. If we have two identical
3234 expressions with side effects that should be treated the same due
3235 to the only side effects being identical SAVE_EXPR's, that will
3236 be detected in the recursive calls below. */
3242 /* Next handle constant cases, those for which we can return 1 even
3243 if ONLY_CONST is set. */
3246 {
3261 {
3262 /* If we do not distinguish between signed and unsigned zero,
3263 consider them equal. */
3266 }
3270 {
3276 {
3278 flags))
3282 }
3285 }
3289 flags)
3291 flags));
3304 }
3309 /* Define macros to test an operand from arg0 and arg1 for equality and a
3310 variant that allows null and views null as being different from any
3311 non-null value. In the latter case, if either is null, the both
3312 must be; otherwise, do the normal comparison. */
3313 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3314 TREE_OPERAND (arg1, N), flags)
3316 #define OP_SAME_WITH_NULL(N) \
3317 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3318 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3321 {
3323 /* Two conversions are equal only if signedness and modes match. */
3325 {
3326 CASE_CONVERT:
3334 }
3344 /* For commutative ops, allow the other order. */
3352 /* If either of the pointer (or reference) expressions we are
3353 dereferencing contain a side effect, these cannot be equal. */
3359 {
3369 /* Operands 2 and 3 may be null.
3370 Compare the array index by value if it is constant first as we
3371 may have different types but same value here. */
3380 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3381 may be NULL when we're called to compare MEM_EXPRs. */
3391 }
3395 {
3410 /* Otherwise take into account this is a commutative operation. */
3421 }
3425 {
3427 /* If the CALL_EXPRs call different functions, then they
3428 clearly can not be equal. */
3430 flags))
3433 {
3437 else
3441 }
3443 /* Now see if all the arguments are the same. */
3444 {
3455 /* If we get here and both argument lists are exhausted
3456 then the CALL_EXPRs are equal. */
3458 }
3461 }
3464 /* Consider __builtin_sqrt equal to sqrt. */
3472 }
3474 #undef OP_SAME
3475 #undef OP_SAME_WITH_NULL
3476 }
3477 \f
3478 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3479 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3481 When in doubt, return 0. */
3483 static int
3485 {
3497 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3498 and see if the inner values are the same. This removes any
3499 signedness comparison, which doesn't matter here. */
3506 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3507 actual comparison operand, ARG0.
3509 First throw away any conversions to wider types
3510 already present in the operands. */
3519 {
3522 /* Make sure shorter operand is extended the right way
3523 to match the longer operand. */
3529 }
3532 }
3533 \f
3534 /* See if ARG is an expression that is either a comparison or is performing
3535 arithmetic on comparisons. The comparisons must only be comparing
3536 two different values, which will be stored in *CVAL1 and *CVAL2; if
3537 they are nonzero it means that some operands have already been found.
3538 No variables may be used anywhere else in the expression except in the
3539 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3540 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3542 If this is true, return 1. Otherwise, return zero. */
3544 static int
3546 {
3550 /* We can handle some of the tcc_expression cases here. */
3560 {
3561 /* If we've already found a CVAL1 or CVAL2, this expression is
3562 two complex to handle. */
3568 }
3571 {
3594 /* First see if we can handle the first operand, then the second. For
3595 the second operand, we know *CVAL1 can't be zero. It must be that
3596 one side of the comparison is each of the values; test for the
3597 case where this isn't true by failing if the two operands
3598 are the same. */
3607 ;
3611 ;
3612 else
3616 ;
3620 ;
3621 else
3628 }
3629 }
3630 \f
3631 /* ARG is a tree that is known to contain just arithmetic operations and
3632 comparisons. Evaluate the operations in the tree substituting NEW0 for
3633 any occurrence of OLD0 as an operand of a comparison and likewise for
3634 NEW1 and OLD1. */
3636 static tree
3639 {
3644 /* We can handle some of the tcc_expression cases here. */
3652 {
3667 {
3686 }
3687 /* Fall through - ??? */
3690 {
3694 /* We need to check both for exact equality and tree equality. The
3695 former will be true if the operand has a side-effect. In that
3696 case, we know the operand occurred exactly once. */
3709 }
3713 }
3714 }
3715 \f
3716 /* Return a tree for the case when the result of an expression is RESULT
3717 converted to TYPE and OMITTED was previously an operand of the expression
3718 but is now not needed (e.g., we folded OMITTED * 0).
3720 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3721 the conversion of RESULT to TYPE. */
3723 tree
3725 {
3728 /* If the resulting operand is an empty statement, just return the omitted
3729 statement casted to void. */
3731 {
3734 }
3737 {
3740 }
3744 omit_one_operand_exit:
3747 }
3749 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3751 static tree
3753 tree omitted)
3754 {
3757 /* If the resulting operand is an empty statement, just return the omitted
3758 statement casted to void. */
3760 {
3763 }
3766 {
3769 }
3773 pedantic_omit_one_operand_exit:
3776 }
3778 /* Return a tree for the case when the result of an expression is RESULT
3779 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3780 of the expression but are now not needed.
3782 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3783 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3784 evaluated before OMITTED2. Otherwise, if neither has side effects,
3785 just do the conversion of RESULT to TYPE. */
3787 tree
3790 {
3794 {
3797 }
3799 {
3802 }
3805 }
3807 \f
3808 /* Return a simplified tree node for the truth-negation of ARG. This
3809 never alters ARG itself. We assume that ARG is an operation that
3810 returns a truth value (0 or 1).
3812 FIXME: one would think we would fold the result, but it causes
3813 problems with the dominator optimizer. */
3815 tree
3817 {
3822 /* If this is a comparison, we can simply invert it, except for
3823 floating-point non-equality comparisons, in which case we just
3824 enclose a TRUTH_NOT_EXPR around what we have. */
3827 {
3830 && flag_trapping_math
3842 }
3845 {
3874 /* Here we can invert either operand. We invert the first operand
3875 unless the second operand is a TRUTH_NOT_EXPR in which case our
3876 result is the XOR of the first operand with the inside of the
3877 negation of the second operand. */
3882 else
3916 {
3927 /* A COND_EXPR may have a throw as one operand, which
3928 then has void type. Just leave void operands
3929 as they are. */
3936 }
3953 CASE_CONVERT:
3955 {
3958 }
3960 /* ... fall through ... */
3991 }
3997 }
3999 /* Return a simplified tree node for the truth-negation of ARG. This
4000 never alters ARG itself. We assume that ARG is an operation that
4001 returns a truth value (0 or 1).
4003 FIXME: one would think we would fold the result, but it causes
4004 problems with the dominator optimizer. */
4006 tree
4008 {
4009 tree tem;
4016 {
4019 }
4022 }
4024 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
4025 operands are another bit-wise operation with a common input. If so,
4026 distribute the bit operations to save an operation and possibly two if
4027 constants are involved. For example, convert
4028 (A | B) & (A | C) into A | (B & C)
4029 Further simplification will occur if B and C are constants.
4031 If this optimization cannot be done, 0 will be returned. */
4033 static tree
4036 {
4037 tree common;
4047 {
4051 }
4053 {
4057 }
4059 {
4063 }
4065 {
4069 }
4070 else
4078 }
4080 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
4081 with code CODE. This optimization is unsafe. */
4082 static tree
4085 {
4089 /* (A / C) +- (B / C) -> (A +- B) / C. */
4099 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
4104 {
4116 }
4119 }
4120 \f
4121 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4122 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
4124 static tree
4127 {
4131 {
4138 }
4153 }
4155 /* Optimize a bit-field compare.
4157 There are two cases: First is a compare against a constant and the
4158 second is a comparison of two items where the fields are at the same
4159 bit position relative to the start of a chunk (byte, halfword, word)
4160 large enough to contain it. In these cases we can avoid the shift
4161 implicit in bitfield extractions.
4163 For constants, we emit a compare of the shifted constant with the
4164 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4165 compared. For two fields at the same position, we do the ANDs with the
4166 similar mask and compare the result of the ANDs.
4168 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4169 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4170 are the left and right operands of the comparison, respectively.
4172 If the optimization described above can be done, we return the resulting
4173 tree. Otherwise we return zero. */
4175 static tree
4178 {
4187 tree mask;
4188 tree offset;
4190 /* Get all the information about the extractions being done. If the bit size
4191 if the same as the size of the underlying object, we aren't doing an
4192 extraction at all and so can do nothing. We also don't want to
4193 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4194 then will no longer be able to replace it. */
4202 {
4203 /* If this is not a constant, we can only do something if bit positions,
4204 sizes, and signedness are the same. */
4212 }
4214 /* See if we can find a mode to refer to this field. We should be able to,
4215 but fail if we can't. */
4224 /* Set signed and unsigned types of the precision of this mode for the
4225 shifts below. */
4229 /* Compute the bit position and size for the new reference and our offset
4230 within it. If the new reference is the same size as the original, we
4231 won't optimize anything, so return zero. */
4241 /* Make the mask to be used against the extracted field. */
4248 /* If not comparing with constant, just rework the comparison
4249 and return. */
4253 unsigned_type,
4256 mask),
4259 unsigned_type,
4262 mask));
4264 /* Otherwise, we are handling the constant case. See if the constant is too
4265 big for the field. Warn and return a tree of for 0 (false) if so. We do
4266 this not only for its own sake, but to avoid having to test for this
4267 error case below. If we didn't, we might generate wrong code.
4269 For unsigned fields, the constant shifted right by the field length should
4270 be all zero. For signed fields, the high-order bits should agree with
4271 the sign bit. */
4274 {
4279 {
4283 }
4284 }
4285 else
4286 {
4291 {
4295 }
4296 }
4298 /* Single-bit compares should always be against zero. */
4300 {
4303 }
4305 /* Make a new bitfield reference, shift the constant over the
4306 appropriate number of bits and mask it with the computed mask
4307 (in case this was a signed field). If we changed it, make a new one. */
4310 {
4313 }
4323 rhs);
4326 }
4327 \f
4328 /* Subroutine for fold_truthop: decode a field reference.
4330 If EXP is a comparison reference, we return the innermost reference.
4332 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4333 set to the starting bit number.
4335 If the innermost field can be completely contained in a mode-sized
4336 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4338 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4339 otherwise it is not changed.
4341 *PUNSIGNEDP is set to the signedness of the field.
4343 *PMASK is set to the mask used. This is either contained in a
4344 BIT_AND_EXPR or derived from the width of the field.
4346 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4348 Return 0 if this is not a component reference or is one that we can't
4349 do anything with. */
4351 static tree
4356 {
4360 tree unsigned_type;
4363 /* All the optimizations using this function assume integer fields.
4364 There are problems with FP fields since the type_for_size call
4365 below can fail for, e.g., XFmode. */
4369 /* We are interested in the bare arrangement of bits, so strip everything
4370 that doesn't affect the machine mode. However, record the type of the
4371 outermost expression if it may matter below. */
4378 {
4384 }
4393 /* If the number of bits in the reference is the same as the bitsize of
4394 the outer type, then the outer type gives the signedness. Otherwise
4395 (in case of a small bitfield) the signedness is unchanged. */
4399 /* Compute the mask to access the bitfield. */
4408 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4416 }
4418 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4419 bit positions. */
4421 static int
4423 {
4426 tree tmask;
4430 return
4437 }
4439 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4440 represents the sign bit of EXP's type. If EXP represents a sign
4441 or zero extension, also test VAL against the unextended type.
4442 The return value is the (sub)expression whose sign bit is VAL,
4443 or NULL_TREE otherwise. */
4445 static tree
4447 {
4451 tree t;
4453 /* Tree EXP must have an integral type. */
4458 /* Tree VAL must be an integer constant. */
4465 {
4472 }
4473 else
4474 {
4481 }
4483 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4484 treat VAL as if it were unsigned. */
4489 /* Handle extension from a narrower type. */
4495 }
4497 /* Subroutine for fold_truthop: determine if an operand is simple enough
4498 to be evaluated unconditionally. */
4500 static int
4502 {
4503 /* Strip any conversions that don't change the machine mode. */
4512 /* Don't regard global variables as simple. They may be
4513 allocated in ways unknown to the compiler (shared memory,
4514 #pragma weak, etc). */
4517 /* Loading a static variable is unduly expensive, but global
4518 registers aren't expensive. */
4520 }
4521 \f
4522 /* The following functions are subroutines to fold_range_test and allow it to
4523 try to change a logical combination of comparisons into a range test.
4525 For example, both
4526 X == 2 || X == 3 || X == 4 || X == 5
4527 and
4528 X >= 2 && X <= 5
4529 are converted to
4530 (unsigned) (X - 2) <= 3
4532 We describe each set of comparisons as being either inside or outside
4533 a range, using a variable named like IN_P, and then describe the
4534 range with a lower and upper bound. If one of the bounds is omitted,
4535 it represents either the highest or lowest value of the type.
4537 In the comments below, we represent a range by two numbers in brackets
4538 preceded by a "+" to designate being inside that range, or a "-" to
4539 designate being outside that range, so the condition can be inverted by
4540 flipping the prefix. An omitted bound is represented by a "-". For
4541 example, "- [-, 10]" means being outside the range starting at the lowest
4542 possible value and ending at 10, in other words, being greater than 10.
4543 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4544 always false.
4546 We set up things so that the missing bounds are handled in a consistent
4547 manner so neither a missing bound nor "true" and "false" need to be
4548 handled using a special case. */
4550 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4551 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4552 and UPPER1_P are nonzero if the respective argument is an upper bound
4553 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4554 must be specified for a comparison. ARG1 will be converted to ARG0's
4555 type if both are specified. */
4557 static tree
4560 {
4561 tree tem;
4565 /* If neither arg represents infinity, do the normal operation.
4566 Else, if not a comparison, return infinity. Else handle the special
4567 comparison rules. Note that most of the cases below won't occur, but
4568 are handled for consistency. */
4571 {
4576 }
4581 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4582 for neither. In real maths, we cannot assume open ended ranges are
4583 the same. But, this is computer arithmetic, where numbers are finite.
4584 We can therefore make the transformation of any unbounded range with
4585 the value Z, Z being greater than any representable number. This permits
4586 us to treat unbounded ranges as equal. */
4590 {
4611 }
4614 }
4615 \f
4616 /* Given EXP, a logical expression, set the range it is testing into
4617 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4618 actually being tested. *PLOW and *PHIGH will be made of the same
4619 type as the returned expression. If EXP is not a comparison, we
4620 will most likely not be returning a useful value and range. Set
4621 *STRICT_OVERFLOW_P to true if the return value is only valid
4622 because signed overflow is undefined; otherwise, do not change
4623 *STRICT_OVERFLOW_P. */
4625 tree
4628 {
4636 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4637 and see if we can refine the range. Some of the cases below may not
4638 happen, but it doesn't seem worth worrying about this. We "continue"
4639 the outer loop when we've changed something; otherwise we "break"
4640 the switch, which will "break" the while. */
4646 {
4651 {
4663 }
4666 {
4673 /* We can only do something if the range is testing for zero
4674 and if the second operand is an integer constant. Note that
4675 saying something is "in" the range we make is done by
4676 complementing IN_P since it will set in the initial case of
4677 being not equal to zero; "out" is leaving it alone. */
4684 {
4705 }
4707 /* If this is an unsigned comparison, we also know that EXP is
4708 greater than or equal to zero. We base the range tests we make
4709 on that fact, so we record it here so we can parse existing
4710 range tests. We test arg0_type since often the return type
4711 of, e.g. EQ_EXPR, is boolean. */
4713 {
4717 NULL_TREE))
4722 /* If the high bound is missing, but we have a nonzero low
4723 bound, reverse the range so it goes from zero to the low bound
4724 minus 1. */
4726 {
4731 }
4732 }
4738 /* (-x) IN [a,b] -> x in [-b, -a] */
4750 /* ~ X -> -X - 1 */
4760 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4761 move a constant to the other side. */
4766 /* If EXP is signed, any overflow in the computation is undefined,
4767 so we don't worry about it so long as our computations on
4768 the bounds don't overflow. For unsigned, overflow is defined
4769 and this is exactly the right thing. */
4781 /* Check for an unsigned range which has wrapped around the maximum
4782 value thus making n_high < n_low, and normalize it. */
4784 {
4790 /* If the range is of the form +/- [ x+1, x ], we won't
4791 be able to normalize it. But then, it represents the
4792 whole range or the empty set, so make it
4793 +/- [ -, - ]. */
4797 else
4799 }
4800 else
4824 /* If we're converting arg0 from an unsigned type, to exp,
4825 a signed type, we will be doing the comparison as unsigned.
4826 The tests above have already verified that LOW and HIGH
4827 are both positive.
4829 So we have to ensure that we will handle large unsigned
4830 values the same way that the current signed bounds treat
4831 negative values. */
4834 {
4835 tree high_positive;
4836 tree equiv_type;
4837 /* For fixed-point modes, we need to pass the saturating flag
4838 as the 2nd parameter. */
4843 else
4847 /* A range without an upper bound is, naturally, unbounded.
4848 Since convert would have cropped a very large value, use
4849 the max value for the destination type. */
4850 high_positive
4857 high_positive),
4860 /* If the low bound is specified, "and" the range with the
4861 range for which the original unsigned value will be
4862 positive. */
4864 {
4868 integer_zero_node),
4869 high_positive))
4873 }
4874 else
4875 {
4876 /* Otherwise, "or" the range with the range of the input
4877 that will be interpreted as negative. */
4881 integer_zero_node),
4882 high_positive))
4886 }
4887 }
4895 }
4898 }
4900 /* If EXP is a constant, we can evaluate whether this is true or false. */
4902 {
4909 }
4913 }
4914 \f
4915 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4916 type, TYPE, return an expression to test if EXP is in (or out of, depending
4917 on IN_P) the range. Return 0 if the test couldn't be created. */
4919 tree
4922 {
4925 #ifdef HAVE_canonicalize_funcptr_for_compare
4926 /* Disable this optimization for function pointer expressions
4927 on targets that require function pointer canonicalization. */
4932 #endif
4935 {
4941 }
4959 {
4961 {
4965 }
4967 }
4969 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4971 {
4973 HOST_WIDE_INT hi;
4978 {
4981 }
4982 else
4983 {
4986 }
4989 {
4991 {
4994 etype
4996 else
4999 }
5002 }
5003 }
5005 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5006 This requires wrap-around arithmetics for the type of the expression.
5007 First make sure that arithmetics in this type is valid, then make sure
5008 that it wraps around. */
5014 {
5017 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
5018 for the type in question, as we rely on this here. */
5028 else
5030 }
5040 {
5042 {
5049 }
5051 }
5059 }
5060 \f
5061 /* Return the predecessor of VAL in its type, handling the infinite case. */
5063 static tree
5065 {
5071 else
5073 }
5075 /* Return the successor of VAL in its type, handling the infinite case. */
5077 static tree
5079 {
5085 else
5087 }
5089 /* Given two ranges, see if we can merge them into one. Return 1 if we
5090 can, 0 if we can't. Set the output range into the specified parameters. */
5092 bool
5095 {
5099 tree tem;
5109 /* Make range 0 be the range that starts first, or ends last if they
5110 start at the same value. Swap them if it isn't. */
5113 || (lowequal
5116 {
5120 }
5122 /* Now flag two cases, whether the ranges are disjoint or whether the
5123 second range is totally subsumed in the first. Note that the tests
5124 below are simplified by the ones above. */
5130 /* We now have four cases, depending on whether we are including or
5131 excluding the two ranges. */
5133 {
5134 /* If they don't overlap, the result is false. If the second range
5135 is a subset it is the result. Otherwise, the range is from the start
5136 of the second to the end of the first. */
5141 else
5143 }
5146 {
5147 /* If they don't overlap, the result is the first range. If they are
5148 equal, the result is false. If the second range is a subset of the
5149 first, and the ranges begin at the same place, we go from just after
5150 the end of the second range to the end of the first. If the second
5151 range is not a subset of the first, or if it is a subset and both
5152 ranges end at the same place, the range starts at the start of the
5153 first range and ends just before the second range.
5154 Otherwise, we can't describe this as a single range. */
5160 {
5165 {
5166 /* We are in the weird situation where high0 > high1 but
5167 high1 has no successor. Punt. */
5169 }
5170 }
5172 {
5177 {
5178 /* low0 < low1 but low1 has no predecessor. Punt. */
5180 }
5181 }
5182 else
5184 }
5187 {
5188 /* If they don't overlap, the result is the second range. If the second
5189 is a subset of the first, the result is false. Otherwise,
5190 the range starts just after the first range and ends at the
5191 end of the second. */
5196 else
5197 {
5202 {
5203 /* high1 > high0 but high0 has no successor. Punt. */
5205 }
5206 }
5207 }
5209 else
5210 {
5211 /* The case where we are excluding both ranges. Here the complex case
5212 is if they don't overlap. In that case, the only time we have a
5213 range is if they are adjacent. If the second is a subset of the
5214 first, the result is the first. Otherwise, the range to exclude
5215 starts at the beginning of the first range and ends at the end of the
5216 second. */
5218 {
5223 else
5224 {
5225 /* Canonicalize - [min, x] into - [-, x]. */
5228 {
5233 /* FALLTHROUGH */
5246 }
5248 /* Canonicalize - [x, max] into - [x, -]. */
5251 {
5256 /* FALLTHROUGH */
5271 }
5273 /* The ranges might be also adjacent between the maximum and
5274 minimum values of the given type. For
5275 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5276 return + [x + 1, y - 1]. */
5278 {
5285 }
5286 else
5288 }
5289 }
5292 else
5294 }
5298 }
5299 \f
5301 /* Subroutine of fold, looking inside expressions of the form
5302 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5303 of the COND_EXPR. This function is being used also to optimize
5304 A op B ? C : A, by reversing the comparison first.
5306 Return a folded expression whose code is not a COND_EXPR
5307 anymore, or NULL_TREE if no folding opportunity is found. */
5309 static tree
5312 {
5317 tree tem;
5322 /* If we have A op 0 ? A : -A, consider applying the following
5323 transformations:
5325 A == 0? A : -A same as -A
5326 A != 0? A : -A same as A
5327 A >= 0? A : -A same as abs (A)
5328 A > 0? A : -A same as abs (A)
5329 A <= 0? A : -A same as -abs (A)
5330 A < 0? A : -A same as -abs (A)
5332 None of these transformations work for modes with signed
5333 zeros. If A is +/-0, the first two transformations will
5334 change the sign of the result (from +0 to -0, or vice
5335 versa). The last four will fix the sign of the result,
5336 even though the original expressions could be positive or
5337 negative, depending on the sign of A.
5339 Note that all these transformations are correct if A is
5340 NaN, since the two alternatives (A and -A) are also NaNs. */
5347 /* In the case that A is of the form X-Y, '-A' (arg2) may
5348 have already been folded to Y-X, check for that. */
5356 {
5370 /* Fall through. */
5392 }
5394 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5395 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5396 both transformations are correct when A is NaN: A != 0
5397 is then true, and A == 0 is false. */
5401 {
5406 }
5408 /* Try some transformations of A op B ? A : B.
5410 A == B? A : B same as B
5411 A != B? A : B same as A
5412 A >= B? A : B same as max (A, B)
5413 A > B? A : B same as max (B, A)
5414 A <= B? A : B same as min (A, B)
5415 A < B? A : B same as min (B, A)
5417 As above, these transformations don't work in the presence
5418 of signed zeros. For example, if A and B are zeros of
5419 opposite sign, the first two transformations will change
5420 the sign of the result. In the last four, the original
5421 expressions give different results for (A=+0, B=-0) and
5422 (A=-0, B=+0), but the transformed expressions do not.
5424 The first two transformations are correct if either A or B
5425 is a NaN. In the first transformation, the condition will
5426 be false, and B will indeed be chosen. In the case of the
5427 second transformation, the condition A != B will be true,
5428 and A will be chosen.
5430 The conversions to max() and min() are not correct if B is
5431 a number and A is not. The conditions in the original
5432 expressions will be false, so all four give B. The min()
5433 and max() versions would give a NaN instead. */
5436 /* Avoid these transformations if the COND_EXPR may be used
5437 as an lvalue in the C++ front-end. PR c++/19199. */
5438 && (in_gimple_form
5443 {
5448 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5450 {
5454 }
5457 {
5466 /* In C++ a ?: expression can be an lvalue, so put the
5467 operand which will be used if they are equal first
5468 so that we can convert this back to the
5469 corresponding COND_EXPR. */
5471 {
5480 }
5487 {
5496 }
5511 }
5512 }
5514 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5515 we might still be able to simplify this. For example,
5516 if C1 is one less or one more than C2, this might have started
5517 out as a MIN or MAX and been transformed by this function.
5518 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5524 {
5528 /* We can replace A with C1 in this case. */
5533 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5534 MIN_EXPR, to preserve the signedness of the comparison. */
5536 OEP_ONLY_CONST)
5540 OEP_ONLY_CONST))
5541 {
5544 arg2));
5547 }
5551 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5552 as above. */
5554 OEP_ONLY_CONST)
5558 OEP_ONLY_CONST))
5559 {
5562 arg2));
5565 }
5569 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5570 MAX_EXPR, to preserve the signedness of the comparison. */
5572 OEP_ONLY_CONST)
5576 OEP_ONLY_CONST))
5577 {
5580 arg2));
5582 }
5586 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5588 OEP_ONLY_CONST)
5592 OEP_ONLY_CONST))
5593 {
5596 arg2));
5598 }
5604 }
5607 }
5610 \f
5611 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5612 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5613 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5614 false) >= 2)
5615 #endif
5617 /* EXP is some logical combination of boolean tests. See if we can
5618 merge it into some range test. Return the new tree if so. */
5620 static tree
5623 {
5631 tree tem;
5635 /* If this is an OR operation, invert both sides; we will invert
5636 again at the end. */
5640 /* If both expressions are the same, if we can merge the ranges, and we
5641 can build the range test, return it or it inverted. If one of the
5642 ranges is always true or always false, consider it to be the same
5643 expression as the other. */
5651 {
5655 }
5657 /* On machines where the branch cost is expensive, if this is a
5658 short-circuited branch and the underlying object on both sides
5659 is the same, make a non-short-circuit operation. */
5665 {
5666 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5667 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5668 which cases we can't do this. */
5670 {
5676 }
5680 {
5689 {
5692 WARN_STRICT_OVERFLOW_COMPARISON);
5698 }
5699 }
5700 }
5703 }
5704 \f
5705 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5706 bit value. Arrange things so the extra bits will be set to zero if and
5707 only if C is signed-extended to its full width. If MASK is nonzero,
5708 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5710 static tree
5712 {
5715 tree temp;
5720 /* We work by getting just the sign bit into the low-order bit, then
5721 into the high-order bit, then sign-extend. We then XOR that value
5722 with C. */
5726 /* We must use a signed type in order to get an arithmetic right shift.
5727 However, we must also avoid introducing accidental overflows, so that
5728 a subsequent call to integer_zerop will work. Hence we must
5729 do the type conversion here. At this point, the constant is either
5730 zero or one, and the conversion to a signed type can never overflow.
5731 We could get an overflow if this conversion is done anywhere else. */
5741 /* If necessary, convert the type back to match the type of C. */
5747 }
5748 \f
5749 /* Find ways of folding logical expressions of LHS and RHS:
5750 Try to merge two comparisons to the same innermost item.
5751 Look for range tests like "ch >= '0' && ch <= '9'".
5752 Look for combinations of simple terms on machines with expensive branches
5753 and evaluate the RHS unconditionally.
5755 For example, if we have p->a == 2 && p->b == 4 and we can make an
5756 object large enough to span both A and B, we can do this with a comparison
5757 against the object ANDed with the a mask.
5759 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5760 operations to do this with one comparison.
5762 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5763 function and the one above.
5765 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5766 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5768 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5769 two operands.
5771 We return the simplified tree or 0 if no optimization is possible. */
5773 static tree
5776 {
5777 /* If this is the "or" of two comparisons, we can do something if
5778 the comparisons are NE_EXPR. If this is the "and", we can do something
5779 if the comparisons are EQ_EXPR. I.e.,
5780 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5782 WANTED_CODE is this operation code. For single bit fields, we can
5783 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5784 comparison for one-bit fields. */
5806 /* Start by getting the comparison codes. Fail if anything is volatile.
5807 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5808 it were surrounded with a NE_EXPR. */
5817 {
5821 }
5824 {
5828 }
5839 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5842 {
5843 tree result;
5846 {
5851 }
5854 {
5860 }
5861 }
5866 /* If the RHS can be evaluated unconditionally and its operands are
5867 simple, it wins to evaluate the RHS unconditionally on machines
5868 with expensive branches. In this case, this isn't a comparison
5869 that can be merged. Avoid doing this if the RHS is a floating-point
5870 comparison since those can trap. */
5877 {
5878 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5884 {
5890 }
5892 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5898 {
5904 }
5907 {
5909 {
5912 }
5914 }
5915 }
5917 /* See if the comparisons can be merged. Then get all the parameters for
5918 each side. */
5942 /* It must be true that the inner operation on the lhs of each
5943 comparison must be the same if we are to be able to do anything.
5944 Then see if we have constants. If not, the same must be true for
5945 the rhs's. */
5956 else
5959 /* If either comparison code is not correct for our logical operation,
5960 fail. However, we can convert a one-bit comparison against zero into
5961 the opposite comparison against that bit being set in the field. */
5965 {
5967 {
5968 /* Make the left operand unsigned, since we are only interested
5969 in the value of one bit. Otherwise we are doing the wrong
5970 thing below. */
5973 }
5974 else
5976 }
5978 /* This is analogous to the code for l_const above. */
5980 {
5982 {
5985 }
5986 else
5988 }
5990 /* See if we can find a mode that contains both fields being compared on
5991 the left. If we can't, fail. Otherwise, update all constants and masks
5992 to be relative to a field of that size. */
5997 volatilep);
6007 {
6010 }
6018 {
6026 {
6030 }
6031 }
6033 {
6041 {
6045 }
6046 }
6048 /* If the right sides are not constant, do the same for it. Also,
6049 disallow this optimization if a size or signedness mismatch occurs
6050 between the left and right sides. */
6052 {
6055 /* Make sure the two fields on the right
6056 correspond to the left without being swapped. */
6064 volatilep);
6074 {
6077 }
6086 /* Make a mask that corresponds to both fields being compared.
6087 Do this for both items being compared. If the operands are the
6088 same size and the bits being compared are in the same position
6089 then we can do this by masking both and comparing the masked
6090 results. */
6094 {
6107 }
6109 /* There is still another way we can do something: If both pairs of
6110 fields being compared are adjacent, we may be able to make a wider
6111 field containing them both.
6113 Note that we still must mask the lhs/rhs expressions. Furthermore,
6114 the mask must be shifted to account for the shift done by
6115 make_bit_field_ref. */
6120 {
6121 tree type;
6135 /* Convert to the smaller type before masking out unwanted bits. */
6138 {
6140 {
6144 }
6146 {
6150 }
6151 }
6161 }
6164 }
6166 /* Handle the case of comparisons with constants. If there is something in
6167 common between the masks, those bits of the constants must be the same.
6168 If not, the condition is always false. Test for this to avoid generating
6169 incorrect code below. */
6174 {
6176 {
6179 }
6180 else
6181 {
6184 }
6185 }
6187 /* Construct the expression we will return. First get the component
6188 reference we will make. Unless the mask is all ones the width of
6189 that field, perform the mask operation. Then compare with the
6190 merged constant. */
6196 {
6199 }
6204 fold_truthop_exit:
6207 }
6208 \f
6209 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
6210 constant. */
6212 static tree
6215 {
6218 tree comp_const;
6219 tree minmax_const;
6221 tree inner;
6232 /* If something does not permit us to optimize, return the original tree. */
6240 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6241 and GT_EXPR, doing the rest with recursive calls using logical
6242 simplifications. */
6244 {
6246 {
6247 tree tem
6254 }
6257 return
6259 optimize_minmax_comparison
6261 optimize_minmax_comparison
6266 /* MAX (X, 0) == 0 -> X <= 0 */
6270 /* MAX (X, 0) == 5 -> X == 5 */
6274 /* MAX (X, 0) == -1 -> false */
6278 /* MIN (X, 0) == 0 -> X >= 0 */
6282 /* MIN (X, 0) == 5 -> false */
6285 else
6286 /* MIN (X, 0) == -1 -> X == -1 */
6291 /* MAX (X, 0) > 0 -> X > 0
6292 MAX (X, 0) > 5 -> X > 5 */
6296 /* MAX (X, 0) > -1 -> true */
6300 /* MIN (X, 0) > 0 -> false
6301 MIN (X, 0) > 5 -> false */
6304 else
6305 /* MIN (X, 0) > -1 -> X > -1 */
6310 }
6311 }
6312 \f
6313 /* T is an integer expression that is being multiplied, divided, or taken a
6314 modulus (CODE says which and what kind of divide or modulus) by a
6315 constant C. See if we can eliminate that operation by folding it with
6316 other operations already in T. WIDE_TYPE, if non-null, is a type that
6317 should be used for the computation if wider than our type.
6319 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6320 (X * 2) + (Y * 4). We must, however, be assured that either the original
6321 expression would not overflow or that overflow is undefined for the type
6322 in the language in question.
6324 If we return a non-null expression, it is an equivalent form of the
6325 original computation, but need not be in the original type.
6327 We set *STRICT_OVERFLOW_P to true if the return values depends on
6328 signed overflow being undefined. Otherwise we do not change
6329 *STRICT_OVERFLOW_P. */
6331 static tree
6334 {
6335 /* To avoid exponential search depth, refuse to allow recursion past
6336 three levels. Beyond that (1) it's highly unlikely that we'll find
6337 something interesting and (2) we've probably processed it before
6338 when we built the inner expression. */
6341 tree ret;
6346 depth++;
6348 depth--;
6351 }
6353 static tree
6356 {
6367 /* Don't deal with constants of zero here; they confuse the code below. */
6377 /* Note that we need not handle conditional operations here since fold
6378 already handles those cases. So just do arithmetic here. */
6380 {
6382 /* For a constant, we can always simplify if we are a multiply
6383 or (for divide and modulus) if it is a multiple of our constant. */
6391 /* If op0 is an expression ... */
6397 /* ... and has wrapping overflow, and its type is smaller
6398 than ctype, then we cannot pass through as widening. */
6404 /* ... or this is a truncation (t is narrower than op0),
6405 then we cannot pass through this narrowing. */
6408 /* ... or signedness changes for division or modulus,
6409 then we cannot pass through this conversion. */
6413 /* ... or has undefined overflow while the converted to
6414 type has not, we cannot do the operation in the inner type
6415 as that would introduce undefined overflow. */
6420 /* Pass the constant down and see if we can make a simplification. If
6421 we can, replace this expression with the inner simplification for
6422 possible later conversion to our or some other type. */
6427 code == MULT_EXPR
6429 strict_overflow_p))))
6434 /* If widening the type changes it from signed to unsigned, then we
6435 must avoid building ABS_EXPR itself as unsigned. */
6437 {
6441 {
6444 }
6446 }
6447 /* If the constant is negative, we cannot simplify this. */
6450 /* FALLTHROUGH */
6458 /* If widening the type changes the signedness, then we can't perform
6459 this optimization as that changes the result. */
6463 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6469 {
6476 }
6480 /* If the second operand is constant, this is a multiplication
6481 or floor division, by a power of two, so we can treat it that
6482 way unless the multiplier or divisor overflows. Signed
6483 left-shift overflow is implementation-defined rather than
6484 undefined in C90, so do not convert signed left shift into
6485 multiplication. */
6488 /* const_binop may not detect overflow correctly,
6489 so check for it explicitly here. */
6494 size_one_node,
6499 ctype,
6501 t1),
6506 /* See if we can eliminate the operation on both sides. If we can, we
6507 can return a new PLUS or MINUS. If we can't, the only remaining
6508 cases where we can do anything are if the second operand is a
6509 constant. */
6515 /* If not multiplication, we can only do this if both operands
6516 are divisible by c. */
6519 {
6524 }
6526 /* If this was a subtraction, negate OP1 and set it to be an addition.
6527 This simplifies the logic below. */
6529 {
6531 /* If OP1 was not easily negatable, the constant may be OP0. */
6533 {
6540 }
6541 }
6546 /* If either OP1 or C are negative, this optimization is not safe for
6547 some of the division and remainder types while for others we need
6548 to change the code. */
6550 {
6558 }
6560 /* If it's a multiply or a division/modulus operation of a multiple
6561 of our constant, do the operation and verify it doesn't overflow. */
6564 {
6567 /* We allow the constant to overflow with wrapping semantics. */
6571 }
6572 else
6575 /* If we have an unsigned type is not a sizetype, we cannot widen
6576 the operation since it will change the result if the original
6577 computation overflowed. */
6583 /* If we were able to eliminate our operation from the first side,
6584 apply our operation to the second side and reform the PLUS. */
6588 /* The last case is if we are a multiply. In that case, we can
6589 apply the distributive law to commute the multiply and addition
6590 if the multiplication of the constants doesn't overflow. */
6596 op1);
6601 /* We have a special case here if we are doing something like
6602 (C * 8) % 4 since we know that's zero. */
6605 /* If the multiplication can overflow we cannot optimize this.
6606 ??? Until we can properly mark individual operations as
6607 not overflowing we need to treat sizetype special here as
6608 stor-layout relies on this opimization to make
6609 DECL_FIELD_BIT_OFFSET always a constant. */
6615 {
6618 }
6620 /* ... fall through ... */
6624 /* If we can extract our operation from the LHS, do so and return a
6625 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6626 do something only if the second operand is a constant. */
6640 /* If these are the same operation types, we can associate them
6641 assuming no overflow. */
6654 /* If these operations "cancel" each other, we have the main
6655 optimizations of this pass, which occur when either constant is a
6656 multiple of the other, in which case we replace this with either an
6657 operation or CODE or TCODE.
6659 If we have an unsigned type that is not a sizetype, we cannot do
6660 this since it will change the result if the original computation
6661 overflowed. */
6669 {
6671 {
6678 }
6680 {
6687 }
6688 }
6693 }
6696 }
6697 \f
6698 /* Return a node which has the indicated constant VALUE (either 0 or
6699 1), and is of the indicated TYPE. */
6701 tree
6703 {
6708 else
6710 }
6713 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6714 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6715 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6716 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6717 COND is the first argument to CODE; otherwise (as in the example
6718 given here), it is the second argument. TYPE is the type of the
6719 original expression. Return NULL_TREE if no simplification is
6720 possible. */
6722 static tree
6727 {
6734 /* This transformation is only worthwhile if we don't have to wrap
6735 arg in a SAVE_EXPR, and the operation can be simplified on at least
6736 one of the branches once its pushed inside the COND_EXPR. */
6741 {
6745 /* If this operand throws an expression, then it does not make
6746 sense to try to perform a logical or arithmetic operation
6747 involving it. */
6752 }
6753 else
6754 {
6759 }
6763 {
6767 else
6769 }
6771 {
6775 else
6777 }
6781 }
6783 \f
6784 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6786 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6787 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6788 ADDEND is the same as X.
6790 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6791 and finite. The problematic cases are when X is zero, and its mode
6792 has signed zeros. In the case of rounding towards -infinity,
6793 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6794 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6796 bool
6798 {
6802 /* Don't allow the fold with -fsignaling-nans. */
6806 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6810 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6815 /* The mode has signed zeros, and we have to honor their sign.
6816 In this situation, there is only one case we can return true for.
6817 X - 0 is the same as X unless rounding towards -infinity is
6818 supported. */
6820 }
6822 /* Subroutine of fold() that checks comparisons of built-in math
6823 functions against real constants.
6825 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6826 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6827 is the type of the result and ARG0 and ARG1 are the operands of the
6828 comparison. ARG1 must be a TREE_REAL_CST.
6830 The function returns the constant folded tree if a simplification
6831 can be made, and NULL_TREE otherwise. */
6833 static tree
6837 {
6838 REAL_VALUE_TYPE c;
6841 {
6847 {
6848 /* sqrt(x) < y is always false, if y is negative. */
6852 /* sqrt(x) > y is always true, if y is negative and we
6853 don't care about NaNs, i.e. negative values of x. */
6857 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6860 }
6862 {
6863 REAL_VALUE_TYPE c2;
6869 {
6870 /* sqrt(x) > y is x == +Inf, when y is very large. */
6875 /* sqrt(x) > y is always false, when y is very large
6876 and we don't care about infinities. */
6878 }
6880 /* sqrt(x) > c is the same as x > c*c. */
6883 }
6885 {
6886 REAL_VALUE_TYPE c2;
6892 {
6893 /* sqrt(x) < y is always true, when y is a very large
6894 value and we don't care about NaNs or Infinities. */
6898 /* sqrt(x) < y is x != +Inf when y is very large and we
6899 don't care about NaNs. */
6904 /* sqrt(x) < y is x >= 0 when y is very large and we
6905 don't care about Infinities. */
6910 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6919 dconst0)),
6922 c2)));
6923 }
6925 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6930 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6933 {
6938 dconst0)),
6941 c2)));
6942 }
6943 }
6944 }
6947 }
6949 /* Subroutine of fold() that optimizes comparisons against Infinities,
6950 either +Inf or -Inf.
6952 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6953 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6954 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6956 The function returns the constant folded tree if a simplification
6957 can be made, and NULL_TREE otherwise. */
6959 static tree
6962 {
6964 REAL_VALUE_TYPE max;
6965 tree temp;
6970 /* For negative infinity swap the sense of the comparison. */
6976 {
6978 /* x > +Inf is always false, if with ignore sNANs. */
6984 /* x <= +Inf is always true, if we don't case about NaNs. */
6988 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6991 {
6994 }
6999 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
7005 /* x < +Inf is always equal to x <= DBL_MAX. */
7011 /* x != +Inf is always equal to !(x > DBL_MAX). */
7023 }
7026 }
7028 /* Subroutine of fold() that optimizes comparisons of a division by
7029 a nonzero integer constant against an integer constant, i.e.
7030 X/C1 op C2.
7032 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
7033 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
7034 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
7036 The function returns the constant folded tree if a simplification
7037 can be made, and NULL_TREE otherwise. */
7039 static tree
7042 {
7047 HOST_WIDE_INT hpart;
7052 /* We have to do this the hard way to detect unsigned overflow.
7053 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
7064 {
7069 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
7077 }
7079 {
7083 {
7102 }
7103 }
7104 else
7105 {
7106 /* A negative divisor reverses the relational operators. */
7112 {
7131 }
7132 }
7135 {
7156 {
7159 }
7164 {
7167 }
7172 {
7175 }
7180 {
7183 }
7188 }
7191 }
7194 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7195 equality/inequality test, then return a simplified form of the test
7196 using a sign testing. Otherwise return NULL. TYPE is the desired
7197 result type. */
7199 static tree
7202 tree result_type)
7203 {
7204 /* If this is testing a single bit, we can optimize the test. */
7208 {
7209 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7210 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7214 /* This is only a win if casting to a signed type is cheap,
7215 i.e. when arg00's type is not a partial mode. */
7218 {
7221 result_type,
7224 }
7225 }
7228 }
7230 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7231 equality/inequality test, then return a simplified form of
7232 the test using shifts and logical operations. Otherwise return
7233 NULL. TYPE is the desired result type. */
7235 tree
7238 {
7239 /* If this is testing a single bit, we can optimize the test. */
7243 {
7252 /* First, see if we can fold the single bit test into a sign-bit
7253 test. */
7255 result_type);
7259 /* Otherwise we have (A & C) != 0 where C is a single bit,
7260 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7261 Similarly for (A & C) == 0. */
7263 /* If INNER is a right shift of a constant and it plus BITNUM does
7264 not overflow, adjust BITNUM and INNER. */
7271 {
7274 }
7276 /* If we are going to be able to omit the AND below, we must do our
7277 operations as unsigned. If we must use the AND, we have a choice.
7278 Normally unsigned is faster, but for some machines signed is. */
7279 #ifdef LOAD_EXTEND_OP
7282 #else
7284 #endif
7300 /* Put the AND last so it can combine with more things. */
7303 /* Make sure to return the proper type. */
7307 }
7309 }
7311 /* Check whether we are allowed to reorder operands arg0 and arg1,
7312 such that the evaluation of arg1 occurs before arg0. */
7314 static bool
7316 {
7323 }
7325 /* Test whether it is preferable two swap two operands, ARG0 and
7326 ARG1, for example because ARG0 is an integer constant and ARG1
7327 isn't. If REORDER is true, only recommend swapping if we can
7328 evaluate the operands in reverse order. */
7330 bool
7332 {
7368 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7369 for commutative and comparison operators. Ensuring a canonical
7370 form allows the optimizers to find additional redundancies without
7371 having to explicitly check for both orderings. */
7377 /* Put SSA_NAMEs last. */
7383 /* Put variables last. */
7390 }
7392 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7393 ARG0 is extended to a wider type. */
7395 static tree
7398 {
7400 tree arg1_unw;
7409 #ifdef HAVE_canonicalize_funcptr_for_compare
7410 /* Disable this optimization if we're casting a function pointer
7411 type on targets that require function pointer canonicalization. */
7416 #endif
7423 /* If possible, express the comparison in the shorter mode. */
7443 /* If we are comparing with the integer that does not fit into the range
7444 of the shorter type, the result is known. */
7455 {
7482 }
7485 }
7487 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7488 ARG0 just the signedness is changed. */
7490 static tree
7493 {
7494 tree arg0_inner;
7504 #ifdef HAVE_canonicalize_funcptr_for_compare
7505 /* Disable this optimization if we're casting a function pointer
7506 type on targets that require function pointer canonicalization. */
7511 #endif
7531 else
7535 }
7537 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7538 step of the array. Reconstructs s and delta in the case of s *
7539 delta being an integer constant (and thus already folded). ADDR is
7540 the address. MULT is the multiplicative expression. If the
7541 function succeeds, the new address expression is returned.
7542 Otherwise NULL_TREE is returned. LOC is the location of the
7543 resulting expression. */
7545 static tree
7547 {
7551 tree itype;
7554 /* Strip the nops that might be added when converting op1 to sizetype. */
7557 /* Canonicalize op1 into a possibly non-constant delta
7558 and an INTEGER_CST s. */
7560 {
7567 {
7570 }
7572 {
7575 }
7576 else
7578 }
7580 {
7583 }
7584 else
7585 {
7586 /* Simulate we are delta * 1. */
7589 }
7592 {
7594 {
7595 tree domain;
7597 /* Remember if this was a multi-dimensional array. */
7611 {
7614 }
7615 else
7616 {
7617 /* Try if delta is a multiple of step. */
7622 }
7624 /* Only fold here if we can verify we do not overflow one
7625 dimension of a multi-dimensional array. */
7627 {
7628 tree tmp;
7643 }
7646 }
7647 else
7652 }
7654 /* We found the suitable array reference. So copy everything up to it,
7655 and replace the index. */
7663 {
7667 }
7675 }
7678 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7679 means A >= Y && A != MAX, but in this case we know that
7680 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7682 static tree
7684 {
7691 else
7700 {
7703 }
7705 {
7708 }
7709 else
7716 {
7717 /* Convert the pointer types into integer before taking the difference. */
7721 }
7722 else
7729 }
7731 /* Fold a sum or difference of at least one multiplication.
7732 Returns the folded tree or NULL if no simplification could be made. */
7734 static tree
7737 {
7741 /* (A * C) +- (B * C) -> (A+-B) * C.
7742 (A * C) +- A -> A * (C+-1).
7743 We are most concerned about the case where C is a constant,
7744 but other combinations show up during loop reduction. Since
7745 it is not difficult, try all four possibilities. */
7748 {
7751 }
7753 {
7756 }
7757 else
7758 {
7759 /* We cannot generate constant 1 for fract. */
7764 }
7766 {
7769 }
7771 {
7773 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7774 the purpose of this canonicalization. */
7778 {
7781 }
7782 else
7784 }
7785 else
7786 {
7787 /* We cannot generate constant 1 for fract. */
7792 }
7804 /* No identical multiplicands; see if we can find a common
7805 power-of-two factor in non-power-of-two multiplies. This
7806 can help in multi-dimensional array access. */
7809 {
7812 tree maybe_same;
7816 /* Move min of absolute values to int11. */
7819 {
7824 }
7825 else
7829 /* The remainder should not be a constant, otherwise we
7830 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7831 increased the number of multiplications necessary. */
7833 {
7841 }
7842 }
7852 }
7854 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7855 specified by EXPR into the buffer PTR of length LEN bytes.
7856 Return the number of bytes placed in the buffer, or zero
7857 upon failure. */
7859 static int
7861 {
7872 {
7876 else
7881 {
7888 else
7890 }
7891 else
7894 }
7896 }
7899 /* Subroutine of native_encode_expr. Encode the REAL_CST
7900 specified by EXPR into the buffer PTR of length LEN bytes.
7901 Return the number of bytes placed in the buffer, or zero
7902 upon failure. */
7904 static int
7906 {
7912 /* There are always 32 bits in each long, no matter the size of
7913 the hosts long. We handle floating point representations with
7914 up to 192 bits. */
7925 {
7930 {
7937 else
7939 }
7940 else
7943 }
7945 }
7947 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7948 specified by EXPR into the buffer PTR of length LEN bytes.
7949 Return the number of bytes placed in the buffer, or zero
7950 upon failure. */
7952 static int
7954 {
7956 tree part;
7967 }
7970 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7971 specified by EXPR into the buffer PTR of length LEN bytes.
7972 Return the number of bytes placed in the buffer, or zero
7973 upon failure. */
7975 static int
7977 {
7987 {
7989 {
7992 }
7993 else
7997 {
8000 }
8001 else
8002 {
8006 }
8008 }
8010 }
8013 /* Subroutine of native_encode_expr. Encode the STRING_CST
8014 specified by EXPR into the buffer PTR of length LEN bytes.
8015 Return the number of bytes placed in the buffer, or zero
8016 upon failure. */
8018 static int
8020 {
8022 HOST_WIDE_INT total_bytes;
8033 {
8037 }
8038 else
8041 }
8044 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
8045 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
8046 buffer PTR of length LEN bytes. Return the number of bytes
8047 placed in the buffer, or zero upon failure. */
8049 int
8051 {
8053 {
8071 }
8072 }
8075 /* Subroutine of native_interpret_expr. Interpret the contents of
8076 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
8077 If the buffer cannot be interpreted, return NULL_TREE. */
8079 static tree
8081 {
8095 {
8098 {
8105 else
8107 }
8108 else
8114 else
8117 }
8120 }
8123 /* Subroutine of native_interpret_expr. Interpret the contents of
8124 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8125 If the buffer cannot be interpreted, return NULL_TREE. */
8127 static tree
8129 {
8134 /* There are always 32 bits in each long, no matter the size of
8135 the hosts long. We handle floating point representations with
8136 up to 192 bits. */
8137 REAL_VALUE_TYPE r;
8148 {
8151 {
8158 else
8160 }
8161 else
8166 }
8170 }
8173 /* Subroutine of native_interpret_expr. Interpret the contents of
8174 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8175 If the buffer cannot be interpreted, return NULL_TREE. */
8177 static tree
8179 {
8194 }
8197 /* Subroutine of native_interpret_expr. Interpret the contents of
8198 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8199 If the buffer cannot be interpreted, return NULL_TREE. */
8201 static tree
8203 {
8215 {
8220 }
8222 }
8225 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8226 the buffer PTR of length LEN as a constant of type TYPE. For
8227 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8228 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8229 return NULL_TREE. */
8231 tree
8233 {
8235 {
8252 }
8253 }
8256 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
8257 TYPE at compile-time. If we're unable to perform the conversion
8258 return NULL_TREE. */
8260 static tree
8262 {
8263 /* We support up to 512-bit values (for V8DFmode). */
8267 /* Check that the host and target are sane. */
8276 }
8278 /* Build an expression for the address of T. Folds away INDIRECT_REF
8279 to avoid confusing the gimplify process. */
8281 tree
8283 {
8284 /* The size of the object is not relevant when talking about its address. */
8288 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8291 {
8295 {
8298 }
8299 }
8301 {
8306 }
8307 else
8308 {
8311 }
8314 }
8316 /* Build an expression for the address of T. */
8318 tree
8320 {
8324 }
8326 /* Fold a unary expression of code CODE and type TYPE with operand
8327 OP0. Return the folded expression if folding is successful.
8328 Otherwise, return NULL_TREE. */
8330 tree
8332 {
8333 tree tem;
8334 tree arg0;
8342 {
8345 {
8346 /* Don't use STRIP_NOPS, because signedness of argument type
8347 matters. */
8349 }
8350 else
8351 {
8352 /* Strip any conversions that don't change the mode. This
8353 is safe for every expression, except for a comparison
8354 expression because its signedness is derived from its
8355 operands.
8357 Note that this is done as an internal manipulation within
8358 the constant folder, in order to find the simplest
8359 representation of the arguments so that their form can be
8360 studied. In any cases, the appropriate type conversions
8361 should be put back in the tree that will get out of the
8362 constant folder. */
8364 }
8365 }
8368 {
8375 {
8389 /* If this was a conversion, and all we did was to move into
8390 inside the COND_EXPR, bring it back out. But leave it if
8391 it is a conversion from integer to integer and the
8392 result precision is no wider than a word since such a
8393 conversion is cheap and may be optimized away by combine,
8394 while it couldn't if it were outside the COND_EXPR. Then return
8395 so we don't get into an infinite recursion loop taking the
8396 conversion out and then back in. */
8408 && (INTEGRAL_TYPE_P
8412 {
8421 }
8423 }
8425 {
8427 {
8431 }
8435 integer_one_node),
8437 integer_zero_node));
8438 }
8439 }
8442 {
8444 /* Re-association barriers around constants and other re-association
8445 barriers can be removed. */
8451 CASE_CONVERT:
8457 /* If we have (type) (a CMP b) and type is an integral type, return
8458 new expression involving the new type. */
8463 /* Handle cases of two conversions in a row. */
8465 {
8487 /* In addition to the cases of two conversions in a row
8488 handled below, if we are converting something to its own
8489 type via an object of identical or wider precision, neither
8490 conversion is needed. */
8497 /* Likewise, if the intermediate and initial types are either both
8498 float or both integer, we don't need the middle conversion if the
8499 former is wider than the latter and doesn't change the signedness
8500 (for integers). Avoid this if the final type is a pointer since
8501 then we sometimes need the middle conversion. Likewise if the
8502 final type has a precision not equal to the size of its mode. */
8511 && ! final_ptr
8515 /* If we have a sign-extension of a zero-extended value, we can
8516 replace that by a single zero-extension. */
8522 /* Two conversions in a row are not needed unless:
8523 - some conversion is floating-point (overstrict for now), or
8524 - some conversion is a vector (overstrict for now), or
8525 - the intermediate type is narrower than both initial and
8526 final, or
8527 - the intermediate type and innermost type differ in signedness,
8528 and the outermost type is wider than the intermediate, or
8529 - the initial type is a pointer type and the precisions of the
8530 intermediate and final types differ, or
8531 - the final type is a pointer type and the precisions of the
8532 initial and intermediate types differ. */
8546 }
8548 /* Handle (T *)&A.B.C for A being of type T and B and C
8549 living at offset zero. This occurs frequently in
8550 C++ upcasting and then accessing the base. */
8554 {
8556 tree offset;
8562 /* If the reference was to a (constant) zero offset, we can use
8563 the address of the base if it has the same base type
8564 as the result type and the pointer type is unqualified. */
8571 }
8575 /* Detect assigning a bitfield. */
8577 && DECL_BIT_FIELD
8579 {
8580 /* Don't leave an assignment inside a conversion
8581 unless assigning a bitfield. */
8583 /* First do the assignment, then return converted constant. */
8589 }
8591 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8592 constants (if x has signed type, the sign bit cannot be set
8593 in c). This folds extension into the BIT_AND_EXPR.
8594 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8595 very likely don't have maximal range for their precision and this
8596 transformation effectively doesn't preserve non-maximal ranges. */
8600 {
8611 <= HOST_BITS_PER_WIDE_INT
8613 {
8620 #ifdef LOAD_EXTEND_OP
8622 && !flag_syntax_only
8625 {
8629 }
8630 #endif
8631 }
8633 {
8639 }
8640 }
8642 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8643 when one of the new casts will fold away. Conservatively we assume
8644 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8650 {
8658 }
8660 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8661 of the same precision, and X is an integer type not narrower than
8662 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8668 {
8674 }
8676 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8677 type of X and Y (integer types only). */
8682 {
8683 /* Be careful not to introduce new overflows. */
8684 tree mult_type;
8687 else
8691 {
8698 }
8699 }
8720 /* For integral conversions with the same precision or pointer
8721 conversions use a NOP_EXPR instead. */
8729 /* Strip inner integral conversions that do not change the precision. */
8753 /* Convert fabs((double)float) into (double)fabsf(float). */
8756 {
8762 targ0));
8763 }
8764 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8770 /* Strip sign ops from argument. */
8772 {
8777 }
8784 {
8790 }
8792 {
8797 }
8807 /* Convert ~ (-A) to A - 1. */
8812 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8821 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8836 /* Perform BIT_NOT_EXPR on each element individually. */
8838 {
8843 {
8845 {
8851 }
8852 else
8855 }
8858 }
8863 /* The argument to invert_truthvalue must have Boolean type. */
8867 /* Note that the operand of this must be an int
8868 and its values must be 0 or 1.
8869 ("true" is a fixed value perhaps depending on the language,
8870 but we don't handle values other than 1 correctly yet.) */
8885 {
8893 }
8895 {
8900 }
8902 {
8906 {
8915 }
8916 }
8928 {
8936 }
8938 {
8942 }
8944 {
8948 {
8957 }
8958 }
8962 /* Fold *&X to X if X is an lvalue. */
8964 {
8971 }
8977 }
8980 /* If the operation was a conversion do _not_ mark a resulting constant
8981 with TREE_OVERFLOW if the original constant was not. These conversions
8982 have implementation defined behavior and retaining the TREE_OVERFLOW
8983 flag here would confuse later passes such as VRP. */
8984 tree
8987 {
8996 }
8998 /* Fold a binary expression of code CODE and type TYPE with operands
8999 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
9000 Return the folded expression if folding is successful. Otherwise,
9001 return NULL_TREE. */
9003 static tree
9005 {
9012 else
9015 /* MIN (MAX (a, b), b) == b. */
9020 /* MIN (MAX (b, a), b) == b. */
9026 /* MIN (a, MAX (a, b)) == a. */
9032 /* MIN (a, MAX (b, a)) == a. */
9039 }
9041 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
9042 by changing CODE to reduce the magnitude of constants involved in
9043 ARG0 of the comparison.
9044 Returns a canonicalized comparison tree if a simplification was
9045 possible, otherwise returns NULL_TREE.
9046 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
9047 valid if signed overflow is undefined. */
9049 static tree
9053 {
9059 /* Match A +- CST code arg1 and CST code arg1. We can change the
9060 first form only if overflow is undefined. */
9062 /* In principle pointers also have undefined overflow behavior,
9063 but that causes problems elsewhere. */
9071 /* Identify the constant in arg0 and its sign. */
9074 else
9078 /* Overflowed constants and zero will cause problems. */
9083 /* See if we can reduce the magnitude of the constant in
9084 arg0 by changing the comparison code. */
9086 {
9087 /* CST <= arg1 -> CST-1 < arg1. */
9090 /* -CST < arg1 -> -CST-1 <= arg1. */
9093 /* CST > arg1 -> CST-1 >= arg1. */
9096 /* -CST >= arg1 -> -CST-1 > arg1. */
9099 else
9101 /* arg1 code' CST' might be more canonical. */
9103 }
9104 else
9105 {
9106 /* A - CST < arg1 -> A - CST-1 <= arg1. */
9110 /* A + CST > arg1 -> A + CST-1 >= arg1. */
9114 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9118 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9122 else
9125 }
9127 /* Now build the constant reduced in magnitude. But not if that
9128 would produce one outside of its types range. */
9136 /* We cannot swap the comparison here as that would cause us to
9137 endlessly recurse. */
9145 /* If swapping might yield to a more canonical form, do so. */
9148 else
9150 }
9152 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9153 overflow further. Try to decrease the magnitude of constants involved
9154 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9155 and put sole constants at the second argument position.
9156 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9158 static tree
9161 {
9162 tree t;
9167 /* Try canonicalization by simplifying arg0. */
9172 {
9176 }
9178 /* Try canonicalization by simplifying arg1 using the swapped
9179 comparison. */
9187 }
9189 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9190 space. This is used to avoid issuing overflow warnings for
9191 expressions like &p->x which can not wrap. */
9193 static bool
9195 {
9206 {
9209 }
9212 else
9213 {
9216 }
9231 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9232 array. */
9234 {
9235 HOST_WIDE_INT base_size;
9240 }
9243 }
9245 /* Subroutine of fold_binary. This routine performs all of the
9246 transformations that are common to the equality/inequality
9247 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9248 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9249 fold_binary should call fold_binary. Fold a comparison with
9250 tree code CODE and type TYPE with operands OP0 and OP1. Return
9251 the folded comparison or NULL_TREE. */
9253 static tree
9256 {
9269 /* If one arg is a real or integer constant, put it last. */
9273 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
9280 {
9284 tree lhs;
9291 /* If the constant operation overflowed this can be
9292 simplified as a comparison against INT_MAX/INT_MIN. */
9295 {
9299 /* Get the sign of the constant on the lhs if the
9300 operation were VARIABLE + CONST1. */
9304 /* The sign of the constant determines if we overflowed
9305 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9306 Canonicalize to the INT_MIN overflow by swapping the comparison
9307 if necessary. */
9311 /* We now can look at the canonicalized case
9312 VARIABLE + 1 CODE2 INT_MIN
9313 and decide on the result. */
9322 }
9327 {
9329 "when changing X +- C1 cmp C2 to "
9331 WARN_STRICT_OVERFLOW_COMPARISON);
9333 }
9334 }
9336 /* For comparisons of pointers we can decompose it to a compile time
9337 comparison of the base objects and the offsets into the object.
9338 This requires at least one operand being an ADDR_EXPR or a
9339 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9345 {
9352 /* Get base and offset for the access. Strip ADDR_EXPR for
9353 get_inner_reference, but put it back by stripping INDIRECT_REF
9354 off the base object if possible. indirect_baseN will be true
9355 if baseN is not an address but refers to the object itself. */
9358 {
9364 else
9366 }
9368 {
9371 }
9375 {
9381 else
9383 }
9385 {
9388 }
9390 /* If we have equivalent bases we might be able to simplify. */
9393 {
9394 /* We can fold this expression to a constant if the non-constant
9395 offset parts are equal. */
9403 {
9410 "occur when comparing P +- C1 with "
9412 WARN_STRICT_OVERFLOW_CONDITIONAL);
9415 {
9429 }
9430 }
9431 /* We can simplify the comparison to a comparison of the variable
9432 offset parts if the constant offset parts are equal.
9433 Be careful to use signed size type here because otherwise we
9434 mess with array offsets in the wrong way. This is possible
9435 because pointer arithmetic is restricted to retain within an
9436 object and overflow on pointer differences is undefined as of
9437 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9441 {
9442 tree signed_size_type_node;
9445 /* By converting to signed size type we cover middle-end pointer
9446 arithmetic which operates on unsigned pointer types of size
9447 type size and ARRAY_REF offsets which are properly sign or
9448 zero extended from their type in case it is narrower than
9449 size type. */
9452 else
9454 offset0);
9457 else
9459 offset1);
9466 "occur when comparing P +- C1 with "
9468 WARN_STRICT_OVERFLOW_COMPARISON);
9471 }
9472 }
9473 /* For non-equal bases we can simplify if they are addresses
9474 of local binding decls or constants. */
9476 /* We know that !operand_equal_p (base0, base1, 0)
9477 because the if condition was false. But make
9478 sure two decls are not the same. */
9492 {
9499 }
9500 /* For equal offsets we can simplify to a comparison of the
9501 base addresses. */
9503 && (indirect_base0
9505 && (indirect_base1
9510 {
9516 }
9517 }
9519 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9520 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9521 the resulting offset is smaller in absolute value than the
9522 original one. */
9530 {
9535 tree cst;
9537 "occur when combining constants around "
9540 /* Put the constant on the side where it doesn't overflow and is
9541 of lower absolute value than before. */
9547 {
9550 variable1,
9554 }
9561 {
9566 variable2);
9567 }
9568 }
9570 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9571 signed arithmetic case. That form is created by the compiler
9572 often enough for folding it to be of value. One example is in
9573 computing loop trip counts after Operator Strength Reduction. */
9579 {
9585 /* Handle unfolded multiplication by zero. */
9590 "eliminating multiplication in comparison "
9592 WARN_STRICT_OVERFLOW_COMPARISON);
9594 /* If const1 is negative we swap the sense of the comparison. */
9599 }
9606 {
9614 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9620 /* (-a) CMP (-b) -> b CMP a */
9627 {
9628 REAL_VALUE_TYPE cst;
9631 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9638 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9639 /* a CMP (-0) -> a CMP 0 */
9644 /* x != NaN is always true, other ops are always false. */
9647 {
9650 }
9652 /* Fold comparisons against infinity. */
9655 {
9659 }
9660 }
9662 /* If this is a comparison of a real constant with a PLUS_EXPR
9663 or a MINUS_EXPR of a real constant, we can convert it into a
9664 comparison with a revised real constant as long as no overflow
9665 occurs when unsafe_math_optimizations are enabled. */
9677 /* Likewise, we can simplify a comparison of a real constant with
9678 a MINUS_EXPR whose first operand is also a real constant, i.e.
9679 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9680 floating-point types only if -fassociative-math is set. */
9691 /* Fold comparisons against built-in math functions. */
9693 && flag_unsafe_math_optimizations
9695 {
9699 {
9703 }
9704 }
9705 }
9709 {
9710 /* If we are widening one operand of an integer comparison,
9711 see if the other operand is similarly being widened. Perhaps we
9712 can do the comparison in the narrower type. */
9717 /* Or if we are changing signedness. */
9721 }
9723 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9724 constant, we can simplify it. */
9729 {
9733 }
9735 /* Simplify comparison of something with itself. (For IEEE
9736 floating-point, we can only do some of these simplifications.) */
9738 {
9740 {
9755 /* For NE, we can only do this simplification if integer
9756 or we don't honor IEEE floating point NaNs. */
9760 /* ... fall through ... */
9766 }
9767 }
9769 /* If we are comparing an expression that just has comparisons
9770 of two integer values, arithmetic expressions of those comparisons,
9771 and constants, we can simplify it. There are only three cases
9772 to check: the two values can either be equal, the first can be
9773 greater, or the second can be greater. Fold the expression for
9774 those three values. Since each value must be 0 or 1, we have
9775 eight possibilities, each of which corresponds to the constant 0
9776 or 1 or one of the six possible comparisons.
9778 This handles common cases like (a > b) == 0 but also handles
9779 expressions like ((x > y) - (y > x)) > 0, which supposedly
9780 occur in macroized code. */
9783 {
9788 /* Don't handle degenerate cases here; they should already
9789 have been handled anyway. */
9798 {
9802 /* We can't just pass T to eval_subst in case cval1 or cval2
9803 was the same as ARG1. */
9805 tree high_result
9809 arg1);
9810 tree equal_result
9814 arg1);
9815 tree low_result
9819 arg1);
9821 /* All three of these results should be 0 or 1. Confirm they are.
9822 Then use those values to select the proper code to use. */
9827 {
9828 /* Make a 3-bit mask with the high-order bit being the
9829 value for `>', the next for '=', and the low for '<'. */
9833 {
9835 /* Always false. */
9856 /* Always true. */
9858 }
9861 {
9865 }
9867 }
9868 }
9869 }
9871 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9872 into a single range test. */
9880 {
9884 }
9886 /* Fold ~X op ~Y as Y op X. */
9889 {
9895 }
9897 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9900 {
9906 }
9909 }
9912 /* Subroutine of fold_binary. Optimize complex multiplications of the
9913 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9914 argument EXPR represents the expression "z" of type TYPE. */
9916 static tree
9918 {
9923 {
9926 }
9928 {
9931 }
9932 else
9933 {
9937 }
9946 }
9949 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9950 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9951 guarantees that P and N have the same least significant log2(M) bits.
9952 N is not otherwise constrained. In particular, N is not normalized to
9953 0 <= N < M as is common. In general, the precise value of P is unknown.
9954 M is chosen as large as possible such that constant N can be determined.
9956 Returns M and sets *RESIDUE to N.
9958 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9959 account. This is not always possible due to PR 35705.
9960 */
9962 static unsigned HOST_WIDE_INT
9965 {
9972 {
9975 {
9977 tree offset;
9985 {
9988 else
9989 /* We don't handle more complicated offset expressions. */
9991 }
9992 }
9997 }
9999 {
10007 allow_func_align);
10013 {
10016 }
10018 {
10021 {
10024 /* Compute the greatest power-of-2 divisor of op1. */
10028 /* If align is non-zero and less than *modulus, replace
10029 *modulus with align., If align is 0, then either op1 is 0
10030 or the greatest power-of-2 divisor of op1 doesn't fit in an
10031 unsigned HOST_WIDE_INT. In either case, no additional
10032 constraint is imposed. */
10037 }
10038 }
10039 }
10041 /* If we get here, we were unable to determine anything useful about the
10042 expression. */
10044 }
10047 /* Fold a binary expression of code CODE and type TYPE with operands
10048 OP0 and OP1. LOC is the location of the resulting expression.
10049 Return the folded expression if folding is successful. Otherwise,
10050 return NULL_TREE. */
10052 tree
10055 {
10069 /* Strip any conversions that don't change the mode. This is
10070 safe for every expression, except for a comparison expression
10071 because its signedness is derived from its operands. So, in
10072 the latter case, only strip conversions that don't change the
10073 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10074 preserved.
10076 Note that this is done as an internal manipulation within the
10077 constant folder, in order to find the simplest representation
10078 of the arguments so that their form can be studied. In any
10079 cases, the appropriate type conversions should be put back in
10080 the tree that will get out of the constant folder. */
10083 {
10086 }
10087 else
10088 {
10091 }
10093 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10094 constant but we can't do arithmetic on them. */
10101 {
10103 {
10104 /* Make sure type and arg0 have the same saturating flag. */
10108 }
10111 else
10115 {
10119 }
10120 }
10122 /* If this is a commutative operation, and ARG0 is a constant, move it
10123 to ARG1 to reduce the number of tests below. */
10128 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10130 First check for cases where an arithmetic operation is applied to a
10131 compound, conditional, or comparison operation. Push the arithmetic
10132 operation inside the compound or conditional to see if any folding
10133 can then be done. Convert comparison to conditional for this purpose.
10134 The also optimizes non-constant cases that used to be done in
10135 expand_expr.
10137 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10138 one of the operands is a comparison and the other is a comparison, a
10139 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10140 code below would make the expression more complex. Change it to a
10141 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10142 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10154 {
10158 boolean_type_node,
10166 }
10170 {
10172 {
10178 }
10181 {
10187 }
10190 {
10196 }
10199 {
10205 }
10206 }
10209 {
10211 /* 0 +p index -> (type)index */
10215 /* PTR +p 0 -> PTR */
10219 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10225 arg1),
10227 arg0)));
10229 /* index +p PTR -> PTR +p index */
10236 /* (PTR +p B) +p A -> PTR +p (B + A) */
10238 {
10239 tree inner;
10248 }
10250 /* PTR_CST +p CST -> CST1 */
10255 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10256 of the array. Loop optimizer sometimes produce this type of
10257 expressions. */
10259 {
10264 }
10269 /* A + (-B) -> A - B */
10275 /* (-A) + B -> B - A */
10284 {
10285 /* Convert ~A + 1 to -A. */
10292 /* ~X + X is -1. */
10295 {
10300 {
10303 }
10304 }
10306 /* X + ~X is -1. */
10309 {
10314 {
10317 }
10318 }
10320 /* X + (X / CST) * -CST is X % CST. */
10325 {
10334 cst0));
10335 }
10336 }
10338 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
10339 same or one. Make sure type is not saturating.
10340 fold_plusminus_mult_expr will re-associate. */
10345 {
10349 }
10352 {
10356 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10357 with a constant, and the two constants have no bits in common,
10358 we should treat this as a BIT_IOR_EXPR since this may produce more
10359 simplifications. */
10367 {
10370 }
10372 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10373 (plus (plus (mult) (mult)) (foo)) so that we can
10374 take advantage of the factoring cases below. */
10381 {
10387 else
10400 parg0),
10402 marg)),
10406 return
10412 parg1)));
10413 }
10414 }
10415 else
10416 {
10417 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10421 /* Likewise if the operands are reversed. */
10425 /* Convert X + -C into X - C. */
10428 {
10434 }
10436 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10437 to __complex__ ( x, y ). This is not the same for SNaNs or
10438 if signed zeros are involved. */
10442 {
10449 {
10453 {
10459 }
10461 {
10467 }
10468 }
10469 }
10477 /* Convert x+x into x*2.0. */
10483 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10484 We associate floats only if the user has specified
10485 -fassociative-math. */
10489 {
10494 {
10495 tree tree0;
10498 }
10499 }
10500 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10501 We associate floats only if the user has specified
10502 -fassociative-math. */
10506 {
10511 {
10512 tree tree0;
10515 }
10516 }
10517 }
10519 bit_rotate:
10520 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10521 is a rotate of A by C1 bits. */
10522 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10523 is a rotate of A by B bits. */
10524 {
10526 tree rtype;
10535 /* Only create rotates in complete modes. Other cases are not
10536 expanded properly. */
10538 {
10554 {
10558 code0 == LSHIFT_EXPR
10562 }
10564 {
10572 TYPE_PRECISION
10576 return
10579 ? LROTATE_EXPR
10583 }
10585 {
10593 TYPE_PRECISION
10597 return fold_convert_loc
10600 ? LROTATE_EXPR
10604 }
10605 }
10606 }
10608 associate:
10609 /* In most languages, can't associate operations on floats through
10610 parentheses. Rather than remember where the parentheses were, we
10611 don't associate floats at all, unless the user has specified
10612 -fassociative-math.
10613 And, we need to make sure type is not saturating. */
10617 {
10622 /* Split both trees into variables, constants, and literals. Then
10623 associate each group together, the constants with literals,
10624 then the result with variables. This increases the chances of
10625 literals being recombined later and of generating relocatable
10626 expressions for the sum of a constant and literal. */
10631 /* With undefined overflow we can only associate constants
10632 with one variable. */
10636 {
10644 /* The only case we can still associate with two variables
10645 is if they are the same, modulo negation. */
10648 }
10650 /* Only do something if we found more than two objects. Otherwise,
10651 nothing has changed and we risk infinite recursion. */
10657 {
10658 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10667 /* Preserve the MINUS_EXPR if the negative part of the literal is
10668 greater than the positive part. Otherwise, the multiplicative
10669 folding code (i.e extract_muldiv) may be fooled in case
10670 unsigned constants are subtracted, like in the following
10671 example: ((X*2 + 4) - 8U)/2. */
10673 {
10677 {
10681 }
10682 else
10683 {
10687 }
10688 }
10690 {
10692 return
10696 else
10697 {
10700 return
10704 }
10705 }
10708 return
10711 }
10712 }
10717 /* Pointer simplifications for subtraction, simple reassociations. */
10719 {
10720 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10723 {
10733 }
10734 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10736 {
10743 }
10744 }
10745 /* A - (-B) -> A + B */
10750 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10761 /* Convert -A - 1 to ~A. */
10770 /* Convert -1 - A to ~A. */
10776 /* X - (X / CST) * CST is X % CST. */
10784 return
10790 {
10796 /* Fold A - (A & B) into ~B & A. */
10799 {
10801 {
10808 }
10810 {
10817 }
10818 }
10820 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10821 any power of 2 minus 1. */
10826 {
10832 {
10836 }
10837 }
10838 }
10840 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10844 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10845 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10846 (-ARG1 + ARG0) reduces to -ARG1. */
10850 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10851 __complex__ ( x, -y ). This is not the same for SNaNs or if
10852 signed zeros are involved. */
10856 {
10863 {
10867 {
10869 arg1r ? arg1r
10874 }
10876 {
10880 arg1i ? arg1i
10883 }
10884 }
10885 }
10887 /* Fold &x - &x. This can happen from &x.foo - &x.
10888 This is unsafe for certain floats even in non-IEEE formats.
10889 In IEEE, it is unsafe because it does wrong for NaNs.
10890 Also note that operand_equal_p is always false if an operand
10891 is volatile. */
10897 /* A - B -> A + (-B) if B is easily negatable. */
10900 /* Avoid this transformation if B is a positive REAL_CST. */
10909 /* Try folding difference of addresses. */
10910 {
10911 HOST_WIDE_INT diff;
10917 }
10919 /* Fold &a[i] - &a[j] to i-j. */
10924 {
10929 {
10937 }
10938 }
10941 && flag_unsafe_math_optimizations
10947 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10948 same or one. Make sure type is not saturating.
10949 fold_plusminus_mult_expr will re-associate. */
10954 {
10958 }
10963 /* (-A) * (-B) -> A * B */
10978 {
10983 /* Transform x * -1 into -x. Make sure to do the negation
10984 on the original operand with conversions not stripped
10985 because we can only strip non-sign-changing conversions. */
10988 /* Transform x * -C into -x * C if x is easily negatable. */
10997 tem);
10999 /* (a * (1 << b)) is (a << b) */
11009 /* (A + A) * C -> A * 2 * C */
11025 {
11028 "occur when simplifying "
11030 WARN_STRICT_OVERFLOW_MISC);
11032 }
11034 /* Optimize z * conj(z) for integer complex numbers. */
11041 }
11042 else
11043 {
11044 /* Maybe fold x * 0 to 0. The expressions aren't the same
11045 when x is NaN, since x * 0 is also NaN. Nor are they the
11046 same in modes with signed zeros, since multiplying a
11047 negative value by 0 gives -0, not +0. */
11052 /* In IEEE floating point, x*1 is not equivalent to x for snans.
11053 Likewise for complex arithmetic with signed zeros. */
11060 /* Transform x * -1.0 into -x. */
11067 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
11068 the result for floating point types due to rounding so it is applied
11069 only if -fassociative-math was specify. */
11074 {
11080 }
11082 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
11084 {
11087 {
11090 }
11091 }
11093 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11094 This is not the same for NaNs or if signed zeros are
11095 involved. */
11101 {
11104 return
11110 return
11115 }
11117 /* Optimize z * conj(z) for floating point complex numbers.
11118 Guarded by flag_unsafe_math_optimizations as non-finite
11119 imaginary components don't produce scalar results. */
11130 {
11134 /* Optimizations of root(...)*root(...). */
11136 {
11141 /* Optimize sqrt(x)*sqrt(x) as x. */
11147 /* Optimize root(x)*root(y) as root(x*y). */
11151 }
11153 /* Optimize expN(x)*expN(y) as expN(x+y). */
11155 {
11161 }
11163 /* Optimizations of pow(...)*pow(...). */
11167 {
11173 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11175 {
11180 }
11182 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11184 {
11189 }
11190 }
11192 /* Optimize tan(x)*cos(x) as sin(x). */
11201 {
11207 }
11209 /* Optimize x*pow(x,c) as pow(x,c+1). */
11213 {
11219 {
11221 REAL_VALUE_TYPE c;
11222 tree arg;
11228 }
11229 }
11231 /* Optimize pow(x,c)*x as pow(x,c+1). */
11235 {
11241 {
11243 REAL_VALUE_TYPE c;
11244 tree arg;
11250 }
11251 }
11253 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
11256 {
11260 {
11263 }
11264 }
11265 }
11266 }
11270 bit_ior:
11278 /* ~X | X is -1. */
11281 {
11285 }
11287 /* X | ~X is -1. */
11290 {
11294 }
11296 /* Canonicalize (X & C1) | C2. */
11300 {
11308 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11314 {
11318 }
11319 else
11320 {
11324 }
11326 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11331 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11332 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11333 mode which allows further optimizations. */
11343 {
11344 unsigned HOST_WIDE_INT mask
11348 {
11352 }
11353 }
11360 arg1);
11361 }
11363 /* (X & Y) | Y is (X, Y). */
11367 /* (X & Y) | X is (Y, X). */
11372 /* X | (X & Y) is (Y, X). */
11377 /* X | (Y & X) is (Y, X). */
11387 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11389 This results in more efficient code for machines without a NAND
11390 instruction. Combine will canonicalize to the first form
11391 which will allow use of NAND instructions provided by the
11392 backend if they exist. */
11395 {
11396 return
11403 }
11405 /* See if this can be simplified into a rotate first. If that
11406 is unsuccessful continue in the association code. */
11417 /* ~X ^ X is -1. */
11420 {
11424 }
11426 /* X ^ ~X is -1. */
11429 {
11433 }
11435 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11436 with a constant, and the two constants have no bits in common,
11437 we should treat this as a BIT_IOR_EXPR since this may produce more
11438 simplifications. */
11446 {
11449 }
11451 /* (X | Y) ^ X -> Y & ~ X*/
11454 {
11457 arg1);
11462 }
11464 /* (Y | X) ^ X -> Y & ~ X*/
11467 {
11470 arg1);
11475 }
11477 /* X ^ (X | Y) -> Y & ~ X*/
11480 {
11483 arg0);
11488 }
11490 /* X ^ (Y | X) -> Y & ~ X*/
11493 {
11496 arg0);
11501 }
11503 /* Convert ~X ^ ~Y to X ^ Y. */
11512 /* Convert ~X ^ C to X ^ ~C. */
11520 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11527 /* Fold (X & Y) ^ Y as ~X & Y. */
11530 {
11535 }
11536 /* Fold (X & Y) ^ X as ~Y & X. */
11540 {
11545 }
11546 /* Fold X ^ (X & Y) as X & ~Y. */
11549 {
11554 }
11555 /* Fold X ^ (Y & X) as ~Y & X. */
11559 {
11564 }
11566 /* See if this can be simplified into a rotate first. If that
11567 is unsuccessful continue in the association code. */
11578 /* ~X & X is always zero. */
11583 /* X & ~X is always zero. */
11588 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11592 {
11598 return
11602 }
11604 /* (X | Y) & Y is (X, Y). */
11608 /* (X | Y) & X is (Y, X). */
11613 /* X & (X | Y) is (Y, X). */
11618 /* X & (Y | X) is (Y, X). */
11624 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11628 {
11634 }
11635 /* Fold ~X & 1 as (X & 1) == 0. */
11638 {
11644 }
11646 /* Fold (X ^ Y) & Y as ~X & Y. */
11649 {
11654 }
11655 /* Fold (X ^ Y) & X as ~Y & X. */
11659 {
11664 }
11665 /* Fold X & (X ^ Y) as X & ~Y. */
11668 {
11673 }
11674 /* Fold X & (Y ^ X) as ~Y & X. */
11678 {
11683 }
11688 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11691 {
11692 unsigned int prec
11698 return
11700 }
11702 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11704 This results in more efficient code for machines without a NOR
11705 instruction. Combine will canonicalize to the first form
11706 which will allow use of NOR instructions provided by the
11707 backend if they exist. */
11710 {
11717 }
11719 /* If arg0 is derived from the address of an object or function, we may
11720 be able to fold this expression using the object or function's
11721 alignment. */
11723 {
11730 /* This works because modulus is a power of 2. If this weren't the
11731 case, we'd have to replace it by its greatest power-of-2
11732 divisor: modulus & -modulus. */
11735 }
11737 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11738 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11739 if the new mask might be further optimized. */
11748 {
11750 unsigned HOST_WIDE_INT mask
11760 {
11763 /* See if more bits can be proven as zero because of
11764 zero extension. */
11767 {
11772 {
11774 /* See if we can shorten the right shift. */
11777 }
11778 }
11782 /* For arithmetic shift if sign bit could be set, zerobits
11783 can contain actually sign bits, so no transformation is
11784 possible, unless MASK masks them all away. In that
11785 case the shift needs to be converted into logical shift. */
11788 {
11791 else
11793 }
11794 }
11796 /* ((X << 16) & 0xff00) is (X, 0). */
11803 {
11806 /* Only do the transformation if NEWMASK is some integer
11807 mode's mask. */
11814 {
11815 tree newmaskt;
11818 {
11824 }
11825 else
11830 }
11831 }
11832 }
11837 /* Don't touch a floating-point divide by zero unless the mode
11838 of the constant can represent infinity. */
11844 /* Optimize A / A to 1.0 if we don't care about
11845 NaNs or Infinities. Skip the transformation
11846 for non-real operands. */
11851 {
11855 }
11857 /* The complex version of the above A / A optimization. */
11860 {
11864 {
11866 /* omit_two_operands will call fold_convert for us. */
11868 }
11869 }
11871 /* (-A) / (-B) -> A / B */
11881 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11886 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11892 /* If ARG1 is a constant, we can convert this to a multiply by the
11893 reciprocal. This does not have the same rounding properties,
11894 so only do this if -freciprocal-math. We can actually
11895 always safely do it if ARG1 is a power of two, but it's hard to
11896 tell if it is or not in a portable manner. */
11898 {
11903 /* Find the reciprocal if optimizing and the result is exact. */
11905 {
11906 REAL_VALUE_TYPE r;
11909 {
11913 }
11914 }
11915 }
11916 /* Convert A/B/C to A/(B*C). */
11923 /* Convert A/(B/C) to (A/B)*C. */
11931 /* Convert C1/(X*C2) into (C1/C2)/X. */
11936 {
11942 }
11945 {
11949 /* Optimize sin(x)/cos(x) as tan(x). */
11955 {
11960 }
11962 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11968 {
11972 {
11977 }
11978 }
11980 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11981 NaNs or Infinities. */
11985 {
11992 {
11997 }
11998 }
12000 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
12001 NaNs or Infinities. */
12005 {
12012 {
12016 {
12020 tmp);
12021 }
12022 }
12023 }
12025 /* Optimize pow(x,c)/x as pow(x,c-1). */
12029 {
12035 {
12037 REAL_VALUE_TYPE c;
12038 tree arg;
12044 }
12045 }
12047 /* Optimize a/root(b/c) into a*root(c/b). */
12049 {
12053 {
12062 }
12063 }
12065 /* Optimize x/expN(y) into x*expN(-y). */
12067 {
12074 }
12076 /* Optimize x/pow(y,z) into x*pow(y,-z). */
12080 {
12088 }
12089 }
12094 /* Simplify A / (B << N) where A and B are positive and B is
12095 a power of 2, to A >> (N + log2(B)). */
12100 {
12103 {
12110 WARN_STRICT_OVERFLOW_MISC);
12116 }
12117 }
12119 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
12120 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12126 /* Fall thru */
12135 /* X / -1 is -X. */
12142 /* Convert -A / -B to A / B when the type is signed and overflow is
12143 undefined. */
12147 {
12150 "when distributing negation across "
12152 WARN_STRICT_OVERFLOW_MISC);
12158 }
12162 {
12165 "when distributing negation across "
12167 WARN_STRICT_OVERFLOW_MISC);
12173 }
12175 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12176 operation, EXACT_DIV_EXPR.
12178 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12179 At one time others generated faster code, it's not clear if they do
12180 after the last round to changes to the DIV code in expmed.c. */
12189 {
12193 WARN_STRICT_OVERFLOW_MISC);
12195 }
12203 /* X % 1 is always zero, but be sure to preserve any side
12204 effects in X. */
12208 /* X % 0, return X % 0 unchanged so that we can get the
12209 proper warnings and errors. */
12213 /* 0 % X is always zero, but be sure to preserve any side
12214 effects in X. Place this after checking for X == 0. */
12218 /* X % -1 is zero. */
12225 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12226 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12231 {
12233 /* Also optimize A % (C << N) where C is a power of 2,
12234 to A & ((C << N) - 1). */
12239 {
12244 "occur when simplifying "
12246 WARN_STRICT_OVERFLOW_MISC);
12250 }
12251 }
12253 /* X % -C is the same as X % C. */
12260 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12267 /* X % -Y is the same as X % Y. */
12279 {
12283 WARN_STRICT_OVERFLOW_MISC);
12285 }
12296 /* Optimize -1 >> x for arithmetic right shifts. */
12300 /* ... fall through ... */
12303 shift:
12309 /* Since negative shift count is not well-defined,
12310 don't try to compute it in the compiler. */
12314 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12319 {
12323 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12324 being well defined. */
12326 {
12332 else
12334 }
12338 }
12340 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12341 into x & ((unsigned)-1 >> c) for unsigned types. */
12349 {
12352 tree lshift;
12353 tree arg00;
12356 {
12363 }
12364 }
12366 /* Rewrite an LROTATE_EXPR by a constant into an
12367 RROTATE_EXPR by a new constant. */
12369 {
12374 }
12376 /* If we have a rotate of a bit operation with the rotate count and
12377 the second operand of the bit operation both constant,
12378 permute the two operations. */
12390 /* Two consecutive rotates adding up to the precision of the
12391 type can be ignored. */
12402 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12403 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12404 if the latter can be further optimized. */
12409 {
12413 arg1);
12417 arg1);
12421 }
12449 /* Note that the operands of this must be ints
12450 and their values must be 0 or 1.
12451 ("true" is a fixed value perhaps depending on the language.) */
12452 /* If first arg is constant zero, return it. */
12456 /* If either arg is constant true, drop it. */
12460 /* Preserve sequence points. */
12463 /* If second arg is constant zero, result is zero, but first arg
12464 must be evaluated. */
12467 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12468 case will be handled here. */
12472 /* !X && X is always false. */
12476 /* X && !X is always false. */
12481 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12482 means A >= Y && A != MAX, but in this case we know that
12483 A < X <= MAX. */
12487 {
12495 }
12497 truth_andor:
12498 /* We only do these simplifications if we are optimizing. */
12502 /* Check for things like (A || B) && (A || C). We can convert this
12503 to A || (B && C). Note that either operator can be any of the four
12504 truth and/or operations and the transformation will still be
12505 valid. Also note that we only care about order for the
12506 ANDIF and ORIF operators. If B contains side effects, this
12507 might change the truth-value of A. */
12514 {
12534 /* This case if tricky because we must either have commutative
12535 operators or else A10 must not have side-effects. */
12541 a01);
12542 }
12544 /* See if we can build a range comparison. */
12548 /* Check for the possibility of merging component references. If our
12549 lhs is another similar operation, try to merge its rhs with our
12550 rhs. Then try to merge our lhs and rhs. */
12562 /* Note that the operands of this must be ints
12563 and their values must be 0 or true.
12564 ("true" is a fixed value perhaps depending on the language.) */
12565 /* If first arg is constant true, return it. */
12569 /* If either arg is constant zero, drop it. */
12573 /* Preserve sequence points. */
12576 /* If second arg is constant true, result is true, but we must
12577 evaluate first arg. */
12580 /* Likewise for first arg, but note this only occurs here for
12581 TRUTH_OR_EXPR. */
12585 /* !X || X is always true. */
12589 /* X || !X is always true. */
12597 /* If the second arg is constant zero, drop it. */
12600 /* If the second arg is constant true, this is a logical inversion. */
12602 {
12603 /* Only call invert_truthvalue if operand is a truth value. */
12606 else
12609 }
12610 /* Identical arguments cancel to zero. */
12614 /* !X ^ X is always true. */
12619 /* X ^ !X is always true. */
12632 /* bool_var != 0 becomes bool_var. */
12637 /* bool_var == 1 becomes bool_var. */
12642 /* bool_var != 1 becomes !bool_var. */
12648 /* bool_var == 0 becomes !bool_var. */
12654 /* !exp != 0 becomes !exp */
12659 /* If this is an equality comparison of the address of two non-weak,
12660 unaliased symbols neither of which are extern (since we do not
12661 have access to attributes for externs), then we know the result. */
12674 {
12675 /* We know that we're looking at the address of two
12676 non-weak, unaliased, static _DECL nodes.
12678 It is both wasteful and incorrect to call operand_equal_p
12679 to compare the two ADDR_EXPR nodes. It is wasteful in that
12680 all we need to do is test pointer equality for the arguments
12681 to the two ADDR_EXPR nodes. It is incorrect to use
12682 operand_equal_p as that function is NOT equivalent to a
12683 C equality test. It can in fact return false for two
12684 objects which would test as equal using the C equality
12685 operator. */
12689 type);
12690 }
12692 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12693 a MINUS_EXPR of a constant, we can convert it into a comparison with
12694 a revised constant as long as no overflow occurs. */
12702 arg1),
12707 /* Similarly for a NEGATE_EXPR. */
12715 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12723 arg1),
12726 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12733 {
12737 val,
12741 }
12743 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12748 {
12750 code == NE_EXPR
12753 }
12755 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12756 for !=. Don't do this for ordered comparisons due to overflow. */
12762 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12767 /* If this is an EQ or NE comparison with zero and ARG0 is
12768 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12769 two operations, but the latter can be done in one less insn
12770 on machines that have only two-operand insns or on which a
12771 constant cannot be the first operand. */
12774 {
12779 {
12786 arg1);
12787 }
12790 {
12797 arg1);
12798 }
12799 }
12801 /* If this is an NE or EQ comparison of zero against the result of a
12802 signed MOD operation whose second operand is a power of 2, make
12803 the MOD operation unsigned since it is simpler and equivalent. */
12811 {
12821 }
12823 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12824 C1 is a valid shift constant, and C2 is a power of two, i.e.
12825 a single bit. */
12829 == INTEGER_CST
12832 {
12837 /* Check for a valid shift count. */
12840 {
12844 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12845 can be rewritten as (X & (C2 << C1)) != 0. */
12847 {
12851 }
12852 /* Otherwise, for signed (arithmetic) shifts,
12853 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12854 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12858 /* Otherwise, of unsigned (logical) shifts,
12859 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12860 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12861 else
12865 arg000);
12866 }
12867 }
12869 /* If this is an NE comparison of zero with an AND of one, remove the
12870 comparison since the AND will give the correct value. */
12877 /* If we have (A & C) == C where C is a power of 2, convert this into
12878 (A & C) != 0. Similarly for NE_EXPR. */
12884 integer_zero_node));
12886 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12887 bit, then fold the expression into A < 0 or A >= 0. */
12892 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12893 Similarly for NE_EXPR. */
12897 {
12906 }
12908 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12909 Similarly for NE_EXPR. */
12913 {
12920 }
12922 /* If this is a comparison of a field, we may be able to simplify it. */
12925 /* Handle the constant case even without -O
12926 to make sure the warnings are given. */
12928 {
12932 }
12934 /* Optimize comparisons of strlen vs zero to a compare of the
12935 first character of the string vs zero. To wit,
12936 strlen(ptr) == 0 => *ptr == 0
12937 strlen(ptr) != 0 => *ptr != 0
12938 Other cases should reduce to one of these two (or a constant)
12939 due to the return value of strlen being unsigned. */
12942 {
12950 {
12955 }
12956 }
12958 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12959 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12963 {
12970 {
12972 {
12975 }
12978 }
12979 }
12981 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12987 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12992 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12999 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
13007 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
13008 (X & C) == 0 when C is a single bit. */
13013 {
13019 }
13021 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
13022 constant C is a power of two, i.e. a single bit. */
13029 {
13033 }
13035 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
13036 when is C is a power of two, i.e. a single bit. */
13043 {
13049 }
13053 {
13056 }
13058 /* Fold -X op -Y as X op Y, where op is eq/ne. */
13065 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
13068 {
13081 arg01),
13090 arg01),
13099 arg00),
13108 arg00),
13110 }
13114 {
13121 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
13122 operand_equal_p guarantees no side-effects so we don't need
13123 to use omit_one_operand on Z. */
13133 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13141 arg10);
13142 }
13144 /* Attempt to simplify equality/inequality comparisons of complex
13145 values. Only lower the comparison if the result is known or
13146 can be simplified to a single scalar comparison. */
13151 {
13156 {
13159 }
13160 else
13161 {
13164 }
13167 {
13170 }
13171 else
13172 {
13175 }
13179 {
13181 {
13186 }
13187 else
13188 {
13193 }
13194 }
13198 {
13200 {
13205 }
13206 else
13207 {
13212 }
13213 }
13214 }
13226 /* Transform comparisons of the form X +- C CMP X. */
13233 {
13240 else
13243 /* (X - c) > X becomes false. */
13247 {
13251 "occur when assuming that (X - c) > X "
13253 WARN_STRICT_OVERFLOW_ALL);
13255 }
13257 /* Likewise (X + c) < X becomes false. */
13261 {
13265 "occur when assuming that "
13267 WARN_STRICT_OVERFLOW_ALL);
13269 }
13271 /* Convert (X - c) <= X to true. */
13276 {
13280 "occur when assuming that "
13282 WARN_STRICT_OVERFLOW_ALL);
13284 }
13286 /* Convert (X + c) >= X to true. */
13291 {
13295 "occur when assuming that "
13297 WARN_STRICT_OVERFLOW_ALL);
13299 }
13302 {
13303 /* Convert X + c > X and X - c < X to true for integers. */
13307 {
13310 "not occur when assuming that "
13312 WARN_STRICT_OVERFLOW_ALL);
13314 }
13319 {
13322 "not occur when assuming that "
13324 WARN_STRICT_OVERFLOW_ALL);
13326 }
13328 /* Convert X + c <= X and X - c >= X to false for integers. */
13332 {
13335 "not occur when assuming that "
13337 WARN_STRICT_OVERFLOW_ALL);
13339 }
13344 {
13347 "not occur when assuming that "
13349 WARN_STRICT_OVERFLOW_ALL);
13351 }
13352 }
13353 }
13355 /* Comparisons with the highest or lowest possible integer of
13356 the specified precision will have known values. */
13357 {
13364 {
13365 HOST_WIDE_INT signed_max_hi;
13370 {
13377 {
13381 }
13382 else
13383 {
13387 }
13388 }
13389 else
13390 {
13399 {
13402 }
13403 else
13404 {
13407 }
13408 }
13413 {
13426 /* The GE_EXPR and LT_EXPR cases above are not normally
13427 reached because of previous transformations. */
13431 }
13433 == max_hi
13436 {
13443 arg1);
13449 arg0),
13450 arg1);
13453 }
13455 == min_hi
13458 {
13473 }
13475 == min_hi
13478 {
13484 arg1);
13489 arg0),
13490 arg1);
13493 }
13498 /* We will flip the signedness of the comparison operator
13499 associated with the mode of arg1, so the sign bit is
13500 specified by this mode. Check that arg1 is the signed
13501 max associated with this sign bit. */
13503 /* signed_type does not work on pointer types. */
13505 {
13506 /* The following case also applies to X < signed_max+1
13507 and X >= signed_max+1 because previous transformations. */
13509 {
13510 tree st;
13516 }
13517 }
13518 }
13519 }
13521 /* If we are comparing an ABS_EXPR with a constant, we can
13522 convert all the cases into explicit comparisons, but they may
13523 well not be faster than doing the ABS and one comparison.
13524 But ABS (X) <= C is a range comparison, which becomes a subtraction
13525 and a comparison, and is probably faster. */
13539 /* Convert ABS_EXPR<x> >= 0 to true. */
13546 {
13549 "when simplifying comparison of "
13551 WARN_STRICT_OVERFLOW_CONDITIONAL);
13553 }
13555 /* Convert ABS_EXPR<x> < 0 to false. */
13560 {
13563 "when simplifying comparison of "
13565 WARN_STRICT_OVERFLOW_CONDITIONAL);
13567 }
13569 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13570 and similarly for >= into !=. */
13575 {
13581 }
13588 {
13597 }
13610 {
13614 }
13616 /* If the first operand is NaN, the result is constant. */
13620 {
13622 ? integer_zero_node
13625 }
13627 /* If the second operand is NaN, the result is constant. */
13631 {
13633 ? integer_zero_node
13636 }
13638 /* Simplify unordered comparison of something with itself. */
13644 && !flag_trapping_math
13648 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13649 {
13661 }
13666 /* When pedantic, a compound expression can be neither an lvalue
13667 nor an integer constant expression. */
13670 /* Don't let (0, 0) be null pointer constant. */
13684 /* An ASSERT_EXPR should never be passed to fold_binary. */
13690 fold_binary_exit:
13693 }
13695 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13696 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13697 of GOTO_EXPR. */
13699 static tree
13701 {
13703 {
13710 /* ... fall through ... */
13714 }
13715 }
13717 /* Return whether the sub-tree ST contains a label which is accessible from
13718 outside the sub-tree. */
13720 static bool
13722 {
13723 return
13725 }
13727 /* Fold a ternary expression of code CODE and type TYPE with operands
13728 OP0, OP1, and OP2. Return the folded expression if folding is
13729 successful. Otherwise, return NULL_TREE. */
13731 tree
13734 {
13735 tree tem;
13742 /* Strip any conversions that don't change the mode. This is safe
13743 for every expression, except for a comparison expression because
13744 its signedness is derived from its operands. So, in the latter
13745 case, only strip conversions that don't change the signedness.
13747 Note that this is done as an internal manipulation within the
13748 constant folder, in order to find the simplest representation of
13749 the arguments so that their form can be studied. In any cases,
13750 the appropriate type conversions should be put back in the tree
13751 that will get out of the constant folder. */
13753 {
13756 }
13759 {
13762 }
13765 {
13769 {
13775 }
13779 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13780 so all simple results must be passed through pedantic_non_lvalue. */
13782 {
13785 /* Only optimize constant conditions when the selected branch
13786 has the same type as the COND_EXPR. This avoids optimizing
13787 away "c ? x : throw", where the throw has a void type.
13788 Avoid throwing away that operand which contains label. */
13795 }
13799 /* If we have A op B ? A : C, we may be able to convert this to a
13800 simpler expression, depending on the operation and the values
13801 of B and C. Signed zeros prevent all of these transformations,
13802 for reasons given above each one.
13804 Also try swapping the arguments and inverting the conditional. */
13809 {
13813 }
13817 op2,
13820 {
13823 {
13827 }
13828 }
13830 /* If the second operand is simpler than the third, swap them
13831 since that produces better jump optimization results. */
13834 {
13835 /* See if this can be inverted. If it can't, possibly because
13836 it was a floating-point inequality comparison, don't do
13837 anything. */
13841 }
13843 /* Convert A ? 1 : 0 to simply A. */
13846 /* If we try to convert OP0 to our type, the
13847 call to fold will try to move the conversion inside
13848 a COND, which will recurse. In that case, the COND_EXPR
13849 is probably the best choice, so leave it alone. */
13853 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13854 over COND_EXPR in cases such as floating point comparisons. */
13861 arg0)));
13863 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13868 {
13869 /* sign_bit_p only checks ARG1 bits within A's precision.
13870 If <sign bit of A> has wider type than A, bits outside
13871 of A's precision in <sign bit of A> need to be checked.
13872 If they are all 0, this optimization needs to be done
13873 in unsigned A's type, if they are all 1 in signed A's type,
13874 otherwise this can't be done. */
13879 {
13881 HOST_WIDE_INT mask_hi;
13883 tree tem_type;
13891 {
13895 }
13896 else
13897 {
13901 }
13903 {
13907 }
13908 else
13914 {
13917 }
13920 {
13923 }
13924 else
13926 }
13929 return
13935 arg1)));
13936 }
13938 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13939 already handled above. */
13944 {
13953 }
13955 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13956 is probably obsolete because the first operand should be a
13957 truth value (that's why we have the two cases above), but let's
13958 leave it in until we can confirm this for all front-ends. */
13970 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13976 arg1);
13978 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13982 {
13983 /* Only perform transformation if ARG0 is easily inverted. */
13988 arg1);
13989 }
13991 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13995 {
13996 /* Only perform transformation if ARG0 is easily inverted. */
14001 op2);
14002 }
14004 /* Convert A ? 1 : B into A || B if A and B are truth values. */
14010 op2);
14015 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
14016 of fold_ternary on them. */
14023 {
14032 {
14037 else
14038 {
14040 tree value;
14044 }
14049 else
14051 }
14052 }
14054 /* A bit-field-ref that referenced the full argument can be stripped. */
14065 }
14067 /* Perform constant folding and related simplification of EXPR.
14068 The related simplifications include x*1 => x, x*0 => 0, etc.,
14069 and application of the associative law.
14070 NOP_EXPR conversions may be removed freely (as long as we
14071 are careful not to change the type of the overall expression).
14072 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14073 but we can constant-fold them if they have constant operands. */
14075 #ifdef ENABLE_FOLD_CHECKING
14076 # define fold(x) fold_1 (x)
14078 static
14079 #endif
14080 tree
14082 {
14086 tree tem;
14089 /* Return right away if a constant. */
14093 /* CALL_EXPR-like objects with variable numbers of operands are
14094 treated specially. */
14096 {
14098 {
14101 }
14103 }
14106 {
14111 {
14129 }
14130 }
14133 {
14135 {
14142 {
14147 /* Find a matching index by means of a binary search. */
14149 {
14165 else
14167 }
14168 }
14171 }
14179 }
14181 #ifdef ENABLE_FOLD_CHECKING
14182 #undef fold
14188 /* When --enable-checking=fold, compute a digest of expr before
14189 and after actual fold call to see if fold did not accidentally
14190 change original expr. */
14192 tree
14194 {
14195 tree ret;
14198 htab_t ht;
14217 }
14219 void
14221 {
14224 htab_t ht;
14234 }
14236 static void
14238 {
14240 }
14242 static void
14244 {
14250 recursive_label:
14264 {
14265 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14269 }
14276 {
14277 /* Allow these fields to be modified. */
14278 tree tmp;
14286 {
14289 }
14290 }
14299 {
14302 {
14316 }
14320 {
14333 }
14350 {
14356 }
14361 {
14365 }
14376 {
14379 }
14389 }
14390 }
14392 /* Helper function for outputting the checksum of a tree T. When
14393 debugging with gdb, you can "define mynext" to be "next" followed
14394 by "call debug_fold_checksum (op0)", then just trace down till the
14395 outputs differ. */
14397 void
14399 {
14414 }
14416 #endif
14418 /* Fold a unary tree expression with code CODE of type TYPE with an
14419 operand OP0. LOC is the location of the resulting expression.
14420 Return a folded expression if successful. Otherwise, return a tree
14421 expression with code CODE of type TYPE with an operand OP0. */
14423 tree
14426 {
14427 tree tem;
14428 #ifdef ENABLE_FOLD_CHECKING
14431 htab_t ht;
14438 #endif
14442 {
14445 }
14447 #ifdef ENABLE_FOLD_CHECKING
14455 #endif
14457 }
14459 /* Fold a binary tree expression with code CODE of type TYPE with
14460 operands OP0 and OP1. LOC is the location of the resulting
14461 expression. Return a folded expression if successful. Otherwise,
14462 return a tree expression with code CODE of type TYPE with operands
14463 OP0 and OP1. */
14465 tree
14468 MEM_STAT_DECL)
14469 {
14470 tree tem;
14471 #ifdef ENABLE_FOLD_CHECKING
14477 htab_t ht;
14489 #endif
14493 {
14496 }
14498 #ifdef ENABLE_FOLD_CHECKING
14514 #endif
14516 }
14518 /* Fold a ternary tree expression with code CODE of type TYPE with
14519 operands OP0, OP1, and OP2. Return a folded expression if
14520 successful. Otherwise, return a tree expression with code CODE of
14521 type TYPE with operands OP0, OP1, and OP2. */
14523 tree
14526 {
14527 tree tem;
14528 #ifdef ENABLE_FOLD_CHECKING
14536 htab_t ht;
14553 #endif
14558 {
14561 }
14563 #ifdef ENABLE_FOLD_CHECKING
14587 #endif
14589 }
14591 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14592 arguments in ARGARRAY, and a null static chain.
14593 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14594 of type TYPE from the given operands as constructed by build_call_array. */
14596 tree
14599 {
14600 tree tem;
14601 #ifdef ENABLE_FOLD_CHECKING
14607 htab_t ht;
14621 #endif
14625 #ifdef ENABLE_FOLD_CHECKING
14642 #endif
14644 }
14646 /* Perform constant folding and related simplification of initializer
14647 expression EXPR. These behave identically to "fold_buildN" but ignore
14648 potential run-time traps and exceptions that fold must preserve. */
14650 #define START_FOLD_INIT \
14651 int saved_signaling_nans = flag_signaling_nans;\
14652 int saved_trapping_math = flag_trapping_math;\
14653 int saved_rounding_math = flag_rounding_math;\
14654 int saved_trapv = flag_trapv;\
14655 int saved_folding_initializer = folding_initializer;\
14656 flag_signaling_nans = 0;\
14657 flag_trapping_math = 0;\
14658 flag_rounding_math = 0;\
14659 flag_trapv = 0;\
14660 folding_initializer = 1;
14662 #define END_FOLD_INIT \
14663 flag_signaling_nans = saved_signaling_nans;\
14664 flag_trapping_math = saved_trapping_math;\
14665 flag_rounding_math = saved_rounding_math;\
14666 flag_trapv = saved_trapv;\
14667 folding_initializer = saved_folding_initializer;
14669 tree
14672 {
14673 tree result;
14674 START_FOLD_INIT;
14678 END_FOLD_INIT;
14680 }
14682 tree
14685 {
14686 tree result;
14687 START_FOLD_INIT;
14691 END_FOLD_INIT;
14693 }
14695 tree
14698 {
14699 tree result;
14700 START_FOLD_INIT;
14704 END_FOLD_INIT;
14706 }
14708 tree
14711 {
14712 tree result;
14713 START_FOLD_INIT;
14717 END_FOLD_INIT;
14719 }
14721 #undef START_FOLD_INIT
14722 #undef END_FOLD_INIT
14724 /* Determine if first argument is a multiple of second argument. Return 0 if
14725 it is not, or we cannot easily determined it to be.
14727 An example of the sort of thing we care about (at this point; this routine
14728 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14729 fold cases do now) is discovering that
14731 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14733 is a multiple of
14735 SAVE_EXPR (J * 8)
14737 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14739 This code also handles discovering that
14741 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14743 is a multiple of 8 so we don't have to worry about dealing with a
14744 possible remainder.
14746 Note that we *look* inside a SAVE_EXPR only to determine how it was
14747 calculated; it is not safe for fold to do much of anything else with the
14748 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14749 at run time. For example, the latter example above *cannot* be implemented
14750 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14751 evaluation time of the original SAVE_EXPR is not necessarily the same at
14752 the time the new expression is evaluated. The only optimization of this
14753 sort that would be valid is changing
14755 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14757 divided by 8 to
14759 SAVE_EXPR (I) * SAVE_EXPR (J)
14761 (where the same SAVE_EXPR (J) is used in the original and the
14762 transformed version). */
14764 int
14766 {
14774 {
14776 /* Bitwise and provides a power of two multiple. If the mask is
14777 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14780 /* FALLTHRU */
14793 {
14797 /* const_binop may not detect overflow correctly,
14798 so check for it explicitly here. */
14804 size_one_node,
14808 }
14812 /* Can't handle conversions from non-integral or wider integral type. */
14818 /* .. fall through ... */
14835 }
14836 }
14838 /* Return true if CODE or TYPE is known to be non-negative. */
14840 static bool
14842 {
14845 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14846 have a signed:1 type (where the value is -1 and 0). */
14849 }
14851 /* Return true if (CODE OP0) is known to be non-negative. If the return
14852 value is based on the assumption that signed overflow is undefined,
14853 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14854 *STRICT_OVERFLOW_P. */
14856 bool
14859 {
14864 {
14866 /* We can't return 1 if flag_wrapv is set because
14867 ABS_EXPR<INT_MIN> = INT_MIN. */
14871 {
14874 }
14881 strict_overflow_p);
14884 {
14889 {
14892 strict_overflow_p);
14894 {
14898 strict_overflow_p);
14899 }
14900 }
14902 {
14905 strict_overflow_p);
14909 }
14910 }
14915 }
14917 /* We don't know sign of `t', so be conservative and return false. */
14919 }
14921 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14922 value is based on the assumption that signed overflow is undefined,
14923 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14924 *STRICT_OVERFLOW_P. */
14926 bool
14929 {
14934 {
14939 strict_overflow_p)
14941 strict_overflow_p));
14943 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14944 both unsigned and at least 2 bits shorter than the result. */
14948 {
14953 {
14957 }
14958 }
14963 {
14964 /* x * x for floating point x is always non-negative. */
14968 strict_overflow_p)
14970 strict_overflow_p));
14971 }
14973 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14974 both unsigned and their total bits is shorter than the result. */
14978 {
14997 {
15007 }
15008 }
15014 strict_overflow_p)
15016 strict_overflow_p));
15027 strict_overflow_p)
15029 strict_overflow_p));
15036 strict_overflow_p);
15039 }
15041 /* We don't know sign of `t', so be conservative and return false. */
15043 }
15045 /* Return true if T is known to be non-negative. If the return
15046 value is based on the assumption that signed overflow is undefined,
15047 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15048 *STRICT_OVERFLOW_P. */
15050 bool
15052 {
15057 {
15069 strict_overflow_p)
15071 strict_overflow_p));
15075 }
15076 /* We don't know sign of `t', so be conservative and return false. */
15078 }
15080 /* Return true if T is known to be non-negative. If the return
15081 value is based on the assumption that signed overflow is undefined,
15082 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15083 *STRICT_OVERFLOW_P. */
15085 bool
15088 {
15091 {
15109 /* Always true. */
15113 /* sqrt(-0.0) is -0.0. */
15117 strict_overflow_p);
15150 /* True if the 1st argument is nonnegative. */
15152 strict_overflow_p);
15155 /* True if the 1st OR 2nd arguments are nonnegative. */
15157 strict_overflow_p)
15159 strict_overflow_p)));
15162 /* True if the 1st AND 2nd arguments are nonnegative. */
15164 strict_overflow_p)
15166 strict_overflow_p)));
15169 /* True if the 2nd argument is nonnegative. */
15171 strict_overflow_p);
15174 /* True if the 1st argument is nonnegative or the second
15175 argument is an even integer. */
15180 strict_overflow_p);
15183 /* True if the 1st argument is nonnegative or the second
15184 argument is an even integer valued real. */
15186 {
15187 REAL_VALUE_TYPE c;
15188 HOST_WIDE_INT n;
15193 {
15194 REAL_VALUE_TYPE cint;
15199 }
15200 }
15202 strict_overflow_p);
15206 }
15208 type);
15209 }
15211 /* Return true if T is known to be non-negative. If the return
15212 value is based on the assumption that signed overflow is undefined,
15213 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15214 *STRICT_OVERFLOW_P. */
15216 bool
15218 {
15224 {
15226 {
15230 /* If the initializer is non-void, then it's a normal expression
15231 that will be assigned to the slot. */
15235 /* Otherwise, the initializer sets the slot in some way. One common
15236 way is an assignment statement at the end of the initializer. */
15238 {
15246 else
15248 }
15252 strict_overflow_p);
15255 }
15258 {
15264 arg0,
15265 arg1,
15266 strict_overflow_p);
15267 }
15271 strict_overflow_p);
15274 strict_overflow_p);
15277 strict_overflow_p);
15282 }
15284 /* We don't know sign of `t', so be conservative and return false. */
15286 }
15288 /* Return true if T is known to be non-negative. If the return
15289 value is based on the assumption that signed overflow is undefined,
15290 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15291 *STRICT_OVERFLOW_P. */
15293 bool
15295 {
15302 {
15309 strict_overflow_p);
15315 strict_overflow_p);
15324 }
15327 {
15335 strict_overflow_p);
15340 strict_overflow_p);
15353 }
15354 }
15356 /* Return true if `t' is known to be non-negative. Handle warnings
15357 about undefined signed overflow. */
15359 bool
15361 {
15368 "determining that expression is always "
15370 WARN_STRICT_OVERFLOW_MISC);
15372 }
15375 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15376 For floating point we further ensure that T is not denormal.
15377 Similar logic is present in nonzero_address in rtlanal.h.
15379 If the return value is based on the assumption that signed overflow
15380 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15381 change *STRICT_OVERFLOW_P. */
15383 bool
15386 {
15388 {
15391 strict_overflow_p);
15394 {
15400 strict_overflow_p));
15401 }
15406 strict_overflow_p);
15410 }
15413 }
15415 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15416 For floating point we further ensure that T is not denormal.
15417 Similar logic is present in nonzero_address in rtlanal.h.
15419 If the return value is based on the assumption that signed overflow
15420 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15421 change *STRICT_OVERFLOW_P. */
15423 bool
15425 tree type,
15426 tree op0,
15428 {
15431 {
15435 {
15436 /* With the presence of negative values it is hard
15437 to say something. */
15444 /* One of operands must be positive and the other non-negative. */
15445 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15446 overflows, on a twos-complement machine the sum of two
15447 nonnegative numbers can never be zero. */
15449 strict_overflow_p)
15451 strict_overflow_p));
15452 }
15457 {
15459 strict_overflow_p)
15461 strict_overflow_p))
15462 {
15465 }
15466 }
15475 {
15478 }
15485 {
15489 /* When both operands are nonzero, then MAX must be too. */
15491 strict_overflow_p))
15494 /* MAX where operand 0 is positive is positive. */
15496 strict_overflow_p);
15497 }
15498 /* MAX where operand 1 is positive is positive. */
15503 {
15507 }
15512 strict_overflow_p)
15514 strict_overflow_p));
15518 }
15521 }
15523 /* Return true when T is an address and is known to be nonzero.
15524 For floating point we further ensure that T is not denormal.
15525 Similar logic is present in nonzero_address in rtlanal.h.
15527 If the return value is based on the assumption that signed overflow
15528 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15529 change *STRICT_OVERFLOW_P. */
15531 bool
15533 {
15536 {
15541 {
15547 /* Weak declarations may link to NULL. Other things may also be NULL
15548 so protect with -fdelete-null-pointer-checks; but not variables
15549 allocated on the stack. */
15551 && (flag_delete_null_pointer_checks
15555 /* Constants are never weak. */
15560 }
15568 {
15572 }
15577 }
15579 }
15581 /* Return true when T is an address and is known to be nonzero.
15582 For floating point we further ensure that T is not denormal.
15583 Similar logic is present in nonzero_address in rtlanal.h.
15585 If the return value is based on the assumption that signed overflow
15586 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15587 change *STRICT_OVERFLOW_P. */
15589 bool
15591 {
15595 /* Doing something useful for floating point would need more work. */
15601 {
15604 strict_overflow_p);
15610 strict_overflow_p);
15618 }
15621 {
15624 strict_overflow_p);
15632 strict_overflow_p);
15647 strict_overflow_p);
15651 strict_overflow_p);
15658 }
15660 }
15662 /* Return true when T is an address and is known to be nonzero.
15663 Handle warnings about undefined signed overflow. */
15665 bool
15667 {
15674 "determining that expression is always "
15676 WARN_STRICT_OVERFLOW_MISC);
15678 }
15680 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15681 attempt to fold the expression to a constant without modifying TYPE,
15682 OP0 or OP1.
15684 If the expression could be simplified to a constant, then return
15685 the constant. If the expression would not be simplified to a
15686 constant, then return NULL_TREE. */
15688 tree
15690 {
15693 }
15695 /* Given the components of a unary expression CODE, TYPE and OP0,
15696 attempt to fold the expression to a constant without modifying
15697 TYPE or OP0.
15699 If the expression could be simplified to a constant, then return
15700 the constant. If the expression would not be simplified to a
15701 constant, then return NULL_TREE. */
15703 tree
15705 {
15708 }
15710 /* If EXP represents referencing an element in a constant string
15711 (either via pointer arithmetic or array indexing), return the
15712 tree representing the value accessed, otherwise return NULL. */
15714 tree
15716 {
15720 {
15722 tree index;
15723 tree string;
15728 else
15729 {
15733 /* Optimize the special-case of a zero lower bound.
15735 We convert the low_bound to sizetype to avoid some problems
15736 with constant folding. (E.g. suppose the lower bound is 1,
15737 and its mode is QI. Without the conversion,l (ARRAY
15738 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15739 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15745 }
15758 }
15760 }
15762 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15763 an integer constant, real, or fixed-point constant.
15765 TYPE is the type of the result. */
15767 static tree
15769 {
15773 {
15775 {
15777 HOST_WIDE_INT high;
15785 }
15792 {
15793 FIXED_VALUE_TYPE f;
15798 /* Propagate overflow flags. */
15802 }
15806 }
15809 }
15811 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15812 an integer constant or real constant.
15814 TYPE is the type of the result. */
15816 tree
15818 {
15822 {
15824 /* If the value is unsigned, then the absolute value is
15825 the same as the ordinary value. */
15828 /* Similarly, if the value is non-negative. */
15831 /* If the value is negative, then the absolute value is
15832 its negation. */
15833 else
15834 {
15836 HOST_WIDE_INT high;
15842 }
15848 else
15854 }
15857 }
15859 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15860 constant. TYPE is the type of the result. */
15862 static tree
15864 {
15874 }
15876 /* Given CODE, a relational operator, the target type, TYPE and two
15877 constant operands OP0 and OP1, return the result of the
15878 relational operation. If the result is not a compile time
15879 constant, then return NULL_TREE. */
15881 static tree
15883 {
15886 /* From here on, the only cases we handle are when the result is
15887 known to be a constant. */
15890 {
15894 /* Handle the cases where either operand is a NaN. */
15896 {
15898 {
15926 }
15929 }
15932 }
15935 {
15939 }
15941 /* Handle equality/inequality of complex constants. */
15943 {
15954 else
15956 }
15958 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15960 To compute GT, swap the arguments and do LT.
15961 To compute GE, do LT and invert the result.
15962 To compute LE, swap the arguments, do LT and invert the result.
15963 To compute NE, do EQ and invert the result.
15965 Therefore, the code below must handle only EQ and LT. */
15968 {
15973 }
15975 /* Note that it is safe to invert for real values here because we
15976 have already handled the one case that it matters. */
15980 {
15983 }
15985 /* Compute a result for LT or EQ if args permit;
15986 Otherwise return T. */
15988 {
15993 else
15995 }
15996 else
16002 }
16004 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
16005 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
16006 itself. */
16008 tree
16010 {
16011 /* If the expression does not have side effects then we don't have to wrap
16012 it with a cleanup point expression. */
16016 /* If the expression is a return, check to see if the expression inside the
16017 return has no side effects or the right hand side of the modify expression
16018 inside the return. If either don't have side effects set we don't need to
16019 wrap the expression in a cleanup point expression. Note we don't check the
16020 left hand side of the modify because it should always be a return decl. */
16022 {
16029 }
16032 }
16034 /* Given a pointer value OP0 and a type TYPE, return a simplified version
16035 of an indirection through OP0, or NULL_TREE if no simplification is
16036 possible. */
16038 tree
16040 {
16042 tree subtype;
16050 {
16053 /* *&CONST_DECL -> to the value of the const decl. */
16056 /* *&p => p; make sure to handle *&"str"[cst] here. */
16058 {
16062 else
16064 }
16065 /* *(foo *)&fooarray => fooarray[0] */
16068 {
16076 }
16077 /* *(foo *)&complexfoo => __real__ complexfoo */
16081 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16084 {
16088 }
16089 }
16091 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16094 {
16097 tree op00type;
16104 {
16116 }
16117 }
16120 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16123 {
16126 tree op00type;
16133 {
16138 }
16139 }
16141 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16144 {
16145 tree type_domain;
16154 }
16157 }
16159 /* Builds an expression for an indirection through T, simplifying some
16160 cases. */
16162 tree
16164 {
16174 }
16176 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16178 tree
16180 {
16185 else
16187 }
16189 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16190 whose result is ignored. The type of the returned tree need not be
16191 the same as the original expression. */
16193 tree
16195 {
16201 {
16212 else
16218 {
16234 }
16239 }
16240 }
16242 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
16243 This can only be applied to objects of a sizetype. */
16245 tree
16247 {
16254 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16255 have to do anything. Only do this when we are not given a const,
16256 because in that case, this check is more expensive than just
16257 doing it. */
16259 {
16264 }
16266 /* If divisor is a power of two, simplify this to bit manipulation. */
16268 {
16270 {
16283 {
16284 high++;
16287 }
16291 }
16292 else
16293 {
16294 tree t;
16300 }
16301 }
16302 else
16303 {
16308 }
16311 }
16313 /* Likewise, but round down. */
16315 tree
16317 {
16324 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16325 have to do anything. Only do this when we are not given a const,
16326 because in that case, this check is more expensive than just
16327 doing it. */
16329 {
16334 }
16336 /* If divisor is a power of two, simplify this to bit manipulation. */
16338 {
16339 tree t;
16343 }
16344 else
16345 {
16350 }
16353 }
16355 /* Returns the pointer to the base of the object addressed by EXP and
16356 extracts the information about the offset of the access, storing it
16357 to PBITPOS and POFFSET. */
16359 static tree
16362 {
16363 tree core;
16366 HOST_WIDE_INT bitsize;
16370 {
16375 }
16376 else
16377 {
16381 }
16384 }
16386 /* Returns true if addresses of E1 and E2 differ by a constant, false
16387 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16389 bool
16391 {
16405 {
16415 }
16417 {
16418 /* If only one of the offsets is non-constant, the difference cannot
16419 be a constant. */
16421 }
16422 else
16427 }
16429 /* Simplify the floating point expression EXP when the sign of the
16430 result is not significant. Return NULL_TREE if no simplification
16431 is possible. */
16433 tree
16435 {
16440 {
16476 {
16479 {
16481 /* Strip copysign function call, return the 1st argument. */
16487 /* Strip sign ops from the argument of "odd" math functions. */
16489 {
16493 }
16495 }
16496 }
16501 }
16503 }