| blob | 803c7a549afbfa4ec6293bc3ec835abfb5ec1b97 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide, size_binop
31 and force_fit_type_double.
33 fold takes a tree as argument and returns a simplified tree.
35 size_binop takes a tree code for an arithmetic operation
36 and two operands that are trees, and produces a tree for the
37 result, assuming the type comes from `sizetype'.
39 size_int takes an integer value, and creates a tree constant
40 with type from `sizetype'.
42 force_fit_type_double takes a constant, an overflowable flag and a
43 prior overflow indicator. It forces the value to fit the type and
44 sets TREE_OVERFLOW.
46 Note: Since the folders get called on non-gimple code as well as
47 gimple code, we need to handle GIMPLE tuples as well as their
48 corresponding tree equivalents. */
70 /* Nonzero if we are folding constants inside an initializer; zero
71 otherwise. */
74 /* The following constants represent a bit based encoding of GCC's
75 comparison operators. This encoding simplifies transformations
76 on relational comparison operators, such as AND and OR. */
94 };
116 HOST_WIDE_INT *,
152 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
153 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
154 and SUM1. Then this yields nonzero if overflow occurred during the
155 addition.
157 Overflow occurs if A and B have the same sign, but A and SUM differ in
158 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
159 sign. */
160 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
161 \f
162 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
163 We do that by representing the two-word integer in 4 words, with only
164 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
165 number. The value of the word is LOWPART + HIGHPART * BASE. */
167 #define LOWPART(x) \
168 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
169 #define HIGHPART(x) \
170 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
171 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
173 /* Unpack a two-word integer into 4 words.
174 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
175 WORDS points to the array of HOST_WIDE_INTs. */
177 static void
179 {
184 }
186 /* Pack an array of 4 words into a two-word integer.
187 WORDS points to the array of words.
188 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
190 static void
193 {
196 }
197 \f
198 /* Force the double-word integer L1, H1 to be within the range of the
199 integer type TYPE. Stores the properly truncated and sign-extended
200 double-word integer in *LV, *HV. Returns true if the operation
201 overflows, that is, argument and result are different. */
203 int
206 {
215 else
218 /* Size types *are* sign extended. */
223 /* First clear all bits that are beyond the type's precision. */
225 ;
228 else
229 {
233 }
235 /* Then do sign extension if necessary. */
241 {
242 /* Sign extend top half? */
246 }
248 {
251 }
252 else
253 {
254 /* Sign extend bottom half? */
256 {
259 }
260 }
265 /* If the value didn't fit, signal overflow. */
267 }
269 /* We force the double-int HIGH:LOW to the range of the type TYPE by
270 sign or zero extending it.
271 OVERFLOWABLE indicates if we are interested
272 in overflow of the value, when >0 we are only interested in signed
273 overflow, for <0 we are interested in any overflow. OVERFLOWED
274 indicates whether overflow has already occurred. CONST_OVERFLOWED
275 indicates whether constant overflow has already occurred. We force
276 T's value to be within range of T's type (by setting to 0 or 1 all
277 the bits outside the type's range). We set TREE_OVERFLOWED if,
278 OVERFLOWED is nonzero,
279 or OVERFLOWABLE is >0 and signed overflow occurs
280 or OVERFLOWABLE is <0 and any overflow occurs
281 We return a new tree node for the extended double-int. The node
282 is shared if no overflow flags are set. */
284 tree
288 {
292 /* Size types *are* sign extended. */
299 /* If we need to set overflow flags, return a new unshared node. */
301 {
305 {
312 }
313 }
315 /* Else build a shared node. */
317 }
318 \f
319 /* Add two doubleword integers with doubleword result.
320 Return nonzero if the operation overflows according to UNSIGNED_P.
321 Each argument is given as two `HOST_WIDE_INT' pieces.
322 One argument is L1 and H1; the other, L2 and H2.
323 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
325 int
330 {
332 HOST_WIDE_INT h;
342 else
344 }
346 /* Negate a doubleword integer with doubleword result.
347 Return nonzero if the operation overflows, assuming it's signed.
348 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
349 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
351 int
354 {
356 {
360 }
361 else
362 {
366 }
367 }
368 \f
369 /* Multiply two doubleword integers with doubleword result.
370 Return nonzero if the operation overflows according to UNSIGNED_P.
371 Each argument is given as two `HOST_WIDE_INT' pieces.
372 One argument is L1 and H1; the other, L2 and H2.
373 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
375 int
380 {
395 {
398 {
400 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
402 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
406 }
408 }
413 /* Unsigned overflow is immediate. */
417 /* Check for signed overflow by calculating the signed representation of the
418 top half of the result; it should agree with the low half's sign bit. */
420 {
423 }
425 {
428 }
430 }
431 \f
432 /* Shift the doubleword integer in L1, H1 left by COUNT places
433 keeping only PREC bits of result.
434 Shift right if COUNT is negative.
435 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
436 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
438 void
442 {
446 {
449 }
455 {
456 /* Shifting by the host word size is undefined according to the
457 ANSI standard, so we must handle this as a special case. */
460 }
462 {
465 }
466 else
467 {
471 }
473 /* Sign extend all bits that are beyond the precision. */
481 ;
483 {
486 }
487 else
488 {
492 }
493 }
495 /* Shift the doubleword integer in L1, H1 right by COUNT places
496 keeping only PREC bits of result. COUNT must be positive.
497 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
498 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
500 void
505 {
508 signmask = (arith
516 {
517 /* Shifting by the host word size is undefined according to the
518 ANSI standard, so we must handle this as a special case. */
521 }
523 {
526 }
527 else
528 {
532 }
534 /* Zero / sign extend all bits that are beyond the precision. */
537 {
540 }
542 ;
544 {
547 }
548 else
549 {
553 }
554 }
555 \f
556 /* Rotate the doubleword integer in L1, H1 left by COUNT places
557 keeping only PREC bits of result.
558 Rotate right if COUNT is negative.
559 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
561 void
565 {
577 }
579 /* Rotate the doubleword integer in L1, H1 left by COUNT places
580 keeping only PREC bits of result. COUNT must be positive.
581 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
583 void
587 {
599 }
600 \f
601 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
602 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
603 CODE is a tree code for a kind of division, one of
604 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
605 or EXACT_DIV_EXPR
606 It controls how the quotient is rounded to an integer.
607 Return nonzero if the operation overflows.
608 UNS nonzero says do unsigned division. */
610 int
613 HOST_WIDE_INT hnum_orig,
615 HOST_WIDE_INT hden_orig,
619 {
635 /* Calculate quotient sign and convert operands to unsigned. */
637 {
639 {
641 /* (minimum integer) / (-1) is the only overflow case. */
645 }
647 {
650 }
651 }
656 /* This unsigned division rounds toward zero. */
659 }
663 /* hden != 0 already checked. */
668 }
678 /* Special code for when the divisor < BASE. */
680 {
681 /* hnum != 0 already checked. */
683 {
687 }
688 }
689 else
690 {
691 /* Full double precision division,
692 with thanks to Don Knuth's "Seminumerical Algorithms". */
696 /* Find the highest nonzero divisor digit. */
699 {
702 }
704 /* Insure that the first digit of the divisor is at least BASE/2.
705 This is required by the quotient digit estimation algorithm. */
712 {
716 }
721 {
726 }
727 }
731 /* Main loop */
733 {
734 /* Guess the next quotient digit, quo_est, by dividing the first
735 two remaining dividend digits by the high order quotient digit.
736 quo_est is never low and is at most 2 high. */
743 else
746 /* Refine quo_est so it's usually correct, and at most one high. */
751 quo_est--;
753 /* Try QUO_EST as the quotient digit, by multiplying the
754 divisor by QUO_EST and subtracting from the remaining dividend.
755 Keep in mind that QUO_EST is the I - 1st digit. */
759 {
765 }
767 /* If quo_est was high by one, then num[i] went negative and
768 we need to correct things. */
770 {
771 quo_est--;
774 {
778 }
781 }
783 /* Store the quotient digit. */
785 }
786 }
790 finish_up:
791 /* If result is negative, make it so. */
795 /* Compute trial remainder: rem = num - (quo * den) */
801 {
810 {
811 /* quo = quo - 1; */
814 }
815 else
822 {
825 }
826 else
832 {
838 /* Get absolute values. */
844 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
853 {
855 /* quo = quo - 1; */
858 else
859 /* quo = quo + 1; */
862 }
863 else
865 }
870 }
872 /* Compute true remainder: rem = num - (quo * den) */
877 }
879 /* If ARG2 divides ARG1 with zero remainder, carries out the division
880 of type CODE and returns the quotient.
881 Otherwise returns NULL_TREE. */
883 tree
885 {
895 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
896 &obj[some_exotic_number]. */
898 {
902 type);
903 }
904 else
915 }
916 \f
917 /* This is nonzero if we should defer warnings about undefined
918 overflow. This facility exists because these warnings are a
919 special case. The code to estimate loop iterations does not want
920 to issue any warnings, since it works with expressions which do not
921 occur in user code. Various bits of cleanup code call fold(), but
922 only use the result if it has certain characteristics (e.g., is a
923 constant); that code only wants to issue a warning if the result is
924 used. */
928 /* If a warning about undefined overflow is deferred, this is the
929 warning. Note that this may cause us to turn two warnings into
930 one, but that is fine since it is sufficient to only give one
931 warning per expression. */
935 /* If a warning about undefined overflow is deferred, this is the
936 level at which the warning should be emitted. */
940 /* Start deferring overflow warnings. We could use a stack here to
941 permit nested calls, but at present it is not necessary. */
943 void
945 {
947 }
949 /* Stop deferring overflow warnings. If there is a pending warning,
950 and ISSUE is true, then issue the warning if appropriate. STMT is
951 the statement with which the warning should be associated (used for
952 location information); STMT may be NULL. CODE is the level of the
953 warning--a warn_strict_overflow_code value. This function will use
954 the smaller of CODE and the deferred code when deciding whether to
955 issue the warning. CODE may be zero to mean to always use the
956 deferred code. */
958 void
960 {
962 location_t locus;
967 {
973 }
984 /* Use the smallest code level when deciding to issue the
985 warning. */
994 else
997 }
999 /* Stop deferring overflow warnings, ignoring any deferred
1000 warnings. */
1002 void
1004 {
1006 }
1008 /* Whether we are deferring overflow warnings. */
1010 bool
1012 {
1014 }
1016 /* This is called when we fold something based on the fact that signed
1017 overflow is undefined. */
1019 static void
1021 {
1023 {
1026 {
1029 }
1030 }
1033 }
1034 \f
1035 /* Return true if the built-in mathematical function specified by CODE
1036 is odd, i.e. -f(x) == f(-x). */
1038 static bool
1040 {
1042 {
1076 }
1078 }
1080 /* Check whether we may negate an integer constant T without causing
1081 overflow. */
1083 bool
1085 {
1088 tree type;
1098 {
1103 }
1104 else
1109 }
1111 /* Determine whether an expression T can be cheaply negated using
1112 the function negate_expr without introducing undefined overflow. */
1114 static bool
1116 {
1117 tree type;
1126 {
1131 /* Check that -CST will not overflow type. */
1157 /* -(A + B) -> (-B) - A. */
1162 /* -(A + B) -> (-A) - B. */
1166 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1176 /* Fall through. */
1189 /* In general we can't negate A / B, because if A is INT_MIN and
1190 B is 1, we may turn this into INT_MIN / -1 which is undefined
1191 and actually traps on some architectures. But if overflow is
1192 undefined, we can negate, because - (INT_MIN / 1) is an
1193 overflow. */
1201 /* Negate -((double)float) as (double)(-float). */
1203 {
1207 }
1211 /* Negate -f(x) as f(-x). */
1217 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1219 {
1225 }
1230 }
1232 }
1234 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1235 simplification is possible.
1236 If negate_expr_p would return true for T, NULL_TREE will never be
1237 returned. */
1239 static tree
1241 {
1243 tree tem;
1246 {
1247 /* Convert - (~A) to A + 1. */
1263 /* Two's complement FP formats, such as c4x, may overflow. */
1273 {
1282 }
1304 {
1305 /* -(A + B) -> (-B) - A. */
1309 {
1313 }
1315 /* -(A + B) -> (-A) - B. */
1317 {
1321 }
1322 }
1326 /* - (A - B) -> B - A */
1338 /* Fall through. */
1342 {
1351 }
1359 /* In general we can't negate A / B, because if A is INT_MIN and
1360 B is 1, we may turn this into INT_MIN / -1 which is undefined
1361 and actually traps on some architectures. But if overflow is
1362 undefined, we can negate, because - (INT_MIN / 1) is an
1363 overflow. */
1365 {
1370 {
1377 }
1380 {
1387 }
1388 }
1392 /* Convert -((double)float) into (double)(-float). */
1394 {
1398 }
1402 /* Negate -f(x) as f(-x). */
1405 {
1411 }
1415 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1417 {
1422 {
1429 }
1430 }
1435 }
1438 }
1440 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1441 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1442 return NULL_TREE. */
1444 static tree
1446 {
1448 location_t loc;
1459 {
1462 }
1464 }
1465 \f
1466 /* Split a tree IN into a constant, literal and variable parts that could be
1467 combined with CODE to make IN. "constant" means an expression with
1468 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1469 commutative arithmetic operation. Store the constant part into *CONP,
1470 the literal in *LITP and return the variable part. If a part isn't
1471 present, set it to null. If the tree does not decompose in this way,
1472 return the entire tree as the variable part and the other parts as null.
1474 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1475 case, we negate an operand that was subtracted. Except if it is a
1476 literal for which we use *MINUS_LITP instead.
1478 If NEGATE_P is true, we are negating all of IN, again except a literal
1479 for which we use *MINUS_LITP instead.
1481 If IN is itself a literal or constant, return it as appropriate.
1483 Note that we do not guarantee that any of the three values will be the
1484 same type as IN, but they will have the same signedness and mode. */
1486 static tree
1489 {
1496 /* Strip any conversions that don't change the machine mode or signedness. */
1505 /* We can associate addition and subtraction together (even
1506 though the C standard doesn't say so) for integers because
1507 the value is not affected. For reals, the value might be
1508 affected, so we can't. */
1511 {
1517 /* First see if either of the operands is a literal, then a constant. */
1530 /* If we haven't dealt with either operand, this is not a case we can
1531 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1536 else
1539 /* Now do any needed negations. */
1546 }
1549 else
1553 {
1560 }
1563 }
1565 /* Re-associate trees split by the above function. T1 and T2 are
1566 either expressions to associate or null. Return the new
1567 expression, if any. LOC is the location of the new expression. If
1568 we build an operation, do it in TYPE and with CODE. */
1570 static tree
1572 {
1573 tree tem;
1580 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1581 try to fold this since we will have infinite recursion. But do
1582 deal with any NEGATE_EXPRs. */
1585 {
1587 {
1596 }
1598 {
1601 }
1606 }
1610 associate_trees_exit:
1613 }
1614 \f
1615 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1616 for use in int_const_binop, size_binop and size_diffop. */
1618 static bool
1620 {
1627 {
1636 }
1641 }
1644 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1645 to produce a new constant. Return NULL_TREE if we don't know how
1646 to evaluate CODE at compile-time.
1648 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1650 tree
1652 {
1656 HOST_WIDE_INT hi;
1658 HOST_WIDE_INT garbageh;
1659 tree t;
1662 int is_sizetype
1672 {
1688 /* It's unclear from the C standard whether shifts can overflow.
1689 The following code ignores overflow; perhaps a C standard
1690 interpretation ruling is needed. */
1719 /* This is a shortcut for a common special case. */
1724 {
1730 }
1732 /* ... fall through ... */
1738 {
1741 }
1744 {
1747 }
1754 /* This is a shortcut for a common special case. */
1759 {
1764 }
1766 /* ... fall through ... */
1784 else
1790 else
1796 }
1799 {
1802 /* Propagate overflow flags ourselves. */
1805 {
1808 }
1809 }
1810 else
1816 }
1818 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1819 constant. We assume ARG1 and ARG2 have the same data type, or at least
1820 are the same kind of constant and the same machine mode. Return zero if
1821 combining the constants is not allowed in the current operating mode.
1823 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1825 static tree
1827 {
1828 /* Sanity check for the recursive cases. */
1839 {
1841 REAL_VALUE_TYPE d1;
1842 REAL_VALUE_TYPE d2;
1843 REAL_VALUE_TYPE value;
1844 REAL_VALUE_TYPE result;
1848 /* The following codes are handled by real_arithmetic. */
1850 {
1861 }
1869 /* Don't perform operation if we honor signaling NaNs and
1870 either operand is a NaN. */
1875 /* Don't perform operation if it would raise a division
1876 by zero exception. */
1882 /* If either operand is a NaN, just return it. Otherwise, set up
1883 for floating-point trap; we return an overflow. */
1892 /* Don't constant fold this floating point operation if
1893 the result has overflowed and flag_trapping_math. */
1901 /* Don't constant fold this floating point operation if the
1902 result may dependent upon the run-time rounding mode and
1903 flag_rounding_math is set, or if GCC's software emulation
1904 is unable to accurately represent the result. */
1914 }
1917 {
1918 FIXED_VALUE_TYPE f1;
1919 FIXED_VALUE_TYPE f2;
1920 FIXED_VALUE_TYPE result;
1925 /* The following codes are handled by fixed_arithmetic. */
1927 {
1944 }
1951 /* Propagate overflow flags. */
1955 }
1958 {
1967 {
1978 notrunc);
1982 notrunc);
1986 {
1987 tree magsquared
1991 notrunc);
1992 tree t1
1996 notrunc);
1997 tree t2
2001 notrunc);
2008 }
2013 }
2017 }
2020 {
2032 {
2035 /* The trailing elements can be empty and should be treated as 0 */
2038 else
2039 {
2042 }
2046 else
2047 {
2050 }
2054 /* It is possible that const_binop cannot handle the given
2055 code and return NULL_TREE */
2060 }
2062 }
2064 }
2066 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2067 indicates which particular sizetype to create. */
2069 tree
2071 {
2073 }
2074 \f
2075 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2076 is a tree code. The type of the result is taken from the operands.
2077 Both must be equivalent integer types, ala int_binop_types_match_p.
2078 If the operands are constant, so is the result. */
2080 tree
2082 {
2091 /* Handle the special case of two integer constants faster. */
2093 {
2094 /* And some specific cases even faster than that. */
2096 {
2101 }
2103 {
2106 }
2108 {
2111 }
2113 /* Handle general case of two integer constants. */
2115 }
2118 }
2120 /* Given two values, either both of sizetype or both of bitsizetype,
2121 compute the difference between the two values. Return the value
2122 in signed type corresponding to the type of the operands. */
2124 tree
2126 {
2128 tree ctype;
2133 /* If the type is already signed, just do the simple thing. */
2141 else
2144 /* If either operand is not a constant, do the conversions to the signed
2145 type and subtract. The hardware will do the right thing with any
2146 overflow in the subtraction. */
2152 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2153 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2154 overflow) and negate (which can't either). Special-case a result
2155 of zero while we're here. */
2161 else
2165 MINUS_EXPR,
2167 }
2168 \f
2169 /* A subroutine of fold_convert_const handling conversions of an
2170 INTEGER_CST to another integer type. */
2172 static tree
2174 {
2175 tree t;
2177 /* Given an integer constant, make new constant with new type,
2178 appropriately sign-extended or truncated. */
2181 /* Don't set the overflow when
2182 converting from a pointer, */
2184 /* or to a sizetype with same signedness
2185 and the precision is unchanged.
2186 ??? sizetype is always sign-extended,
2187 but its signedness depends on the
2188 frontend. Thus we see spurious overflows
2189 here if we do not check this. */
2204 }
2206 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2207 to an integer type. */
2209 static tree
2211 {
2213 tree t;
2215 /* The following code implements the floating point to integer
2216 conversion rules required by the Java Language Specification,
2217 that IEEE NaNs are mapped to zero and values that overflow
2218 the target precision saturate, i.e. values greater than
2219 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2220 are mapped to INT_MIN. These semantics are allowed by the
2221 C and C++ standards that simply state that the behavior of
2222 FP-to-integer conversion is unspecified upon overflow. */
2225 REAL_VALUE_TYPE r;
2229 {
2236 }
2238 /* If R is NaN, return zero and show we have an overflow. */
2240 {
2244 }
2246 /* See if R is less than the lower bound or greater than the
2247 upper bound. */
2250 {
2254 {
2258 }
2259 }
2262 {
2265 {
2268 {
2272 }
2273 }
2274 }
2282 }
2284 /* A subroutine of fold_convert_const handling conversions of a
2285 FIXED_CST to an integer type. */
2287 static tree
2289 {
2290 tree t;
2294 /* Right shift FIXED_CST to temp by fbit. */
2298 {
2303 /* Left shift temp to temp_trunc by fbit. */
2308 }
2309 else
2310 {
2315 }
2317 /* If FIXED_CST is negative, we need to round the value toward 0.
2318 By checking if the fractional bits are not zero to add 1 to temp. */
2321 {
2322 double_int one;
2326 }
2328 /* Given a fixed-point constant, make new constant with new type,
2329 appropriately sign-extended or truncated. */
2337 }
2339 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2340 to another floating point type. */
2342 static tree
2344 {
2345 REAL_VALUE_TYPE value;
2346 tree t;
2351 /* If converting an infinity or NAN to a representation that doesn't
2352 have one, set the overflow bit so that we can produce some kind of
2353 error message at the appropriate point if necessary. It's not the
2354 most user-friendly message, but it's better than nothing. */
2361 /* Regular overflow, conversion produced an infinity in a mode that
2362 can't represent them. */
2367 else
2370 }
2372 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2373 to a floating point type. */
2375 static tree
2377 {
2378 REAL_VALUE_TYPE value;
2379 tree t;
2386 }
2388 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2389 to another fixed-point type. */
2391 static tree
2393 {
2394 FIXED_VALUE_TYPE value;
2395 tree t;
2402 /* Propagate overflow flags. */
2406 }
2408 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2409 to a fixed-point type. */
2411 static tree
2413 {
2414 FIXED_VALUE_TYPE value;
2415 tree t;
2424 /* Propagate overflow flags. */
2428 }
2430 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2431 to a fixed-point type. */
2433 static tree
2435 {
2436 FIXED_VALUE_TYPE value;
2437 tree t;
2445 /* Propagate overflow flags. */
2449 }
2451 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2452 type TYPE. If no simplification can be done return NULL_TREE. */
2454 static tree
2456 {
2462 {
2469 }
2471 {
2478 }
2480 {
2487 }
2489 }
2491 /* Construct a vector of zero elements of vector type TYPE. */
2493 static tree
2495 {
2506 }
2508 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2510 bool
2512 {
2527 {
2546 }
2547 }
2549 /* Convert expression ARG to type TYPE. Used by the middle-end for
2550 simple conversions in preference to calling the front-end's convert. */
2552 tree
2554 {
2556 tree tem;
2570 {
2575 {
2579 }
2593 {
2597 }
2599 {
2603 }
2605 {
2609 }
2612 {
2630 }
2635 {
2639 }
2642 {
2656 }
2660 {
2669 integer_zero_node));
2671 {
2675 {
2681 }
2689 }
2693 }
2711 }
2712 fold_convert_exit:
2715 }
2716 \f
2717 /* Return false if expr can be assumed not to be an lvalue, true
2718 otherwise. */
2720 static bool
2722 {
2723 /* We only need to wrap lvalue tree codes. */
2725 {
2759 /* Assume the worst for front-end tree codes. */
2763 }
2766 }
2768 /* Return an expr equal to X but certainly not valid as an lvalue. */
2770 tree
2772 {
2773 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2774 us. */
2783 }
2785 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2786 Zero means allow extended lvalues. */
2790 /* When pedantic, return an expr equal to X but certainly not valid as a
2791 pedantic lvalue. Otherwise, return X. */
2793 static tree
2795 {
2800 }
2801 \f
2802 /* Given a tree comparison code, return the code that is the logical inverse
2803 of the given code. It is not safe to do this for floating-point
2804 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2805 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2807 enum tree_code
2809 {
2814 {
2845 }
2846 }
2848 /* Similar, but return the comparison that results if the operands are
2849 swapped. This is safe for floating-point. */
2851 enum tree_code
2853 {
2855 {
2881 }
2882 }
2885 /* Convert a comparison tree code from an enum tree_code representation
2886 into a compcode bit-based encoding. This function is the inverse of
2887 compcode_to_comparison. */
2889 static enum comparison_code
2891 {
2893 {
2924 }
2925 }
2927 /* Convert a compcode bit-based encoding of a comparison operator back
2928 to GCC's enum tree_code representation. This function is the
2929 inverse of comparison_to_compcode. */
2931 static enum tree_code
2933 {
2935 {
2966 }
2967 }
2969 /* Return a tree for the comparison which is the combination of
2970 doing the AND or OR (depending on CODE) of the two operations LCODE
2971 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2972 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2973 if this makes the transformation invalid. */
2975 tree
2980 {
2987 {
2998 }
3001 {
3002 /* Eliminate unordered comparisons, as well as LTGT and ORD
3003 which are not used unless the mode has NaNs. */
3009 }
3011 {
3012 /* Check that the original operation and the optimized ones will trap
3013 under the same condition. */
3024 /* In a short-circuited boolean expression the LHS might be
3025 such that the RHS, if evaluated, will never trap. For
3026 example, in ORD (x, y) && (x < y), we evaluate the RHS only
3027 if neither x nor y is NaN. (This is a mixed blessing: for
3028 example, the expression above will never trap, hence
3029 optimizing it to x < y would be invalid). */
3034 /* If the comparison was short-circuited, and only the RHS
3035 trapped, we may now generate a spurious trap. */
3040 /* If we changed the conditions that cause a trap, we lose. */
3043 }
3049 else
3050 {
3055 }
3056 }
3057 \f
3058 /* Return nonzero if two operands (typically of the same tree node)
3059 are necessarily equal. If either argument has side-effects this
3060 function returns zero. FLAGS modifies behavior as follows:
3062 If OEP_ONLY_CONST is set, only return nonzero for constants.
3063 This function tests whether the operands are indistinguishable;
3064 it does not test whether they are equal using C's == operation.
3065 The distinction is important for IEEE floating point, because
3066 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3067 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3069 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3070 even though it may hold multiple values during a function.
3071 This is because a GCC tree node guarantees that nothing else is
3072 executed between the evaluation of its "operands" (which may often
3073 be evaluated in arbitrary order). Hence if the operands themselves
3074 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3075 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3076 unset means assuming isochronic (or instantaneous) tree equivalence.
3077 Unless comparing arbitrary expression trees, such as from different
3078 statements, this flag can usually be left unset.
3080 If OEP_PURE_SAME is set, then pure functions with identical arguments
3081 are considered the same. It is used when the caller has other ways
3082 to ensure that global memory is unchanged in between. */
3084 int
3086 {
3087 /* If either is ERROR_MARK, they aren't equal. */
3091 /* Check equality of integer constants before bailing out due to
3092 precision differences. */
3096 /* If both types don't have the same signedness, then we can't consider
3097 them equal. We must check this before the STRIP_NOPS calls
3098 because they may change the signedness of the arguments. As pointers
3099 strictly don't have a signedness, require either two pointers or
3100 two non-pointers as well. */
3105 /* If both types don't have the same precision, then it is not safe
3106 to strip NOPs. */
3113 /* In case both args are comparisons but with different comparison
3114 code, try to swap the comparison operands of one arg to produce
3115 a match and compare that variant. */
3119 {
3127 }
3130 /* This is needed for conversions and for COMPONENT_REF.
3131 Might as well play it safe and always test this. */
3137 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3138 We don't care about side effects in that case because the SAVE_EXPR
3139 takes care of that for us. In all other cases, two expressions are
3140 equal if they have no side effects. If we have two identical
3141 expressions with side effects that should be treated the same due
3142 to the only side effects being identical SAVE_EXPR's, that will
3143 be detected in the recursive calls below. */
3149 /* Next handle constant cases, those for which we can return 1 even
3150 if ONLY_CONST is set. */
3153 {
3168 {
3169 /* If we do not distinguish between signed and unsigned zero,
3170 consider them equal. */
3173 }
3177 {
3183 {
3185 flags))
3189 }
3192 }
3196 flags)
3198 flags));
3211 }
3216 /* Define macros to test an operand from arg0 and arg1 for equality and a
3217 variant that allows null and views null as being different from any
3218 non-null value. In the latter case, if either is null, the both
3219 must be; otherwise, do the normal comparison. */
3220 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3221 TREE_OPERAND (arg1, N), flags)
3223 #define OP_SAME_WITH_NULL(N) \
3224 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3225 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3228 {
3230 /* Two conversions are equal only if signedness and modes match. */
3232 {
3233 CASE_CONVERT:
3241 }
3251 /* For commutative ops, allow the other order. */
3259 /* If either of the pointer (or reference) expressions we are
3260 dereferencing contain a side effect, these cannot be equal. */
3266 {
3276 /* Operands 2 and 3 may be null.
3277 Compare the array index by value if it is constant first as we
3278 may have different types but same value here. */
3287 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3288 may be NULL when we're called to compare MEM_EXPRs. */
3298 }
3302 {
3317 /* Otherwise take into account this is a commutative operation. */
3328 }
3332 {
3334 /* If the CALL_EXPRs call different functions, then they
3335 clearly can not be equal. */
3337 flags))
3340 {
3344 else
3348 }
3350 /* Now see if all the arguments are the same. */
3351 {
3362 /* If we get here and both argument lists are exhausted
3363 then the CALL_EXPRs are equal. */
3365 }
3368 }
3371 /* Consider __builtin_sqrt equal to sqrt. */
3379 }
3381 #undef OP_SAME
3382 #undef OP_SAME_WITH_NULL
3383 }
3384 \f
3385 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3386 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3388 When in doubt, return 0. */
3390 static int
3392 {
3404 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3405 and see if the inner values are the same. This removes any
3406 signedness comparison, which doesn't matter here. */
3413 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3414 actual comparison operand, ARG0.
3416 First throw away any conversions to wider types
3417 already present in the operands. */
3426 {
3429 /* Make sure shorter operand is extended the right way
3430 to match the longer operand. */
3436 }
3439 }
3440 \f
3441 /* See if ARG is an expression that is either a comparison or is performing
3442 arithmetic on comparisons. The comparisons must only be comparing
3443 two different values, which will be stored in *CVAL1 and *CVAL2; if
3444 they are nonzero it means that some operands have already been found.
3445 No variables may be used anywhere else in the expression except in the
3446 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3447 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3449 If this is true, return 1. Otherwise, return zero. */
3451 static int
3453 {
3457 /* We can handle some of the tcc_expression cases here. */
3467 {
3468 /* If we've already found a CVAL1 or CVAL2, this expression is
3469 two complex to handle. */
3475 }
3478 {
3501 /* First see if we can handle the first operand, then the second. For
3502 the second operand, we know *CVAL1 can't be zero. It must be that
3503 one side of the comparison is each of the values; test for the
3504 case where this isn't true by failing if the two operands
3505 are the same. */
3514 ;
3518 ;
3519 else
3523 ;
3527 ;
3528 else
3535 }
3536 }
3537 \f
3538 /* ARG is a tree that is known to contain just arithmetic operations and
3539 comparisons. Evaluate the operations in the tree substituting NEW0 for
3540 any occurrence of OLD0 as an operand of a comparison and likewise for
3541 NEW1 and OLD1. */
3543 static tree
3546 {
3551 /* We can handle some of the tcc_expression cases here. */
3559 {
3574 {
3593 }
3594 /* Fall through - ??? */
3597 {
3601 /* We need to check both for exact equality and tree equality. The
3602 former will be true if the operand has a side-effect. In that
3603 case, we know the operand occurred exactly once. */
3616 }
3620 }
3621 }
3622 \f
3623 /* Return a tree for the case when the result of an expression is RESULT
3624 converted to TYPE and OMITTED was previously an operand of the expression
3625 but is now not needed (e.g., we folded OMITTED * 0).
3627 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3628 the conversion of RESULT to TYPE. */
3630 tree
3632 {
3635 /* If the resulting operand is an empty statement, just return the omitted
3636 statement casted to void. */
3638 {
3641 }
3644 {
3647 }
3651 omit_one_operand_exit:
3654 }
3656 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3658 static tree
3660 tree omitted)
3661 {
3664 /* If the resulting operand is an empty statement, just return the omitted
3665 statement casted to void. */
3667 {
3670 }
3673 {
3676 }
3680 pedantic_omit_one_operand_exit:
3683 }
3685 /* Return a tree for the case when the result of an expression is RESULT
3686 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3687 of the expression but are now not needed.
3689 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3690 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3691 evaluated before OMITTED2. Otherwise, if neither has side effects,
3692 just do the conversion of RESULT to TYPE. */
3694 tree
3697 {
3701 {
3704 }
3706 {
3709 }
3712 }
3714 \f
3715 /* Return a simplified tree node for the truth-negation of ARG. This
3716 never alters ARG itself. We assume that ARG is an operation that
3717 returns a truth value (0 or 1).
3719 FIXME: one would think we would fold the result, but it causes
3720 problems with the dominator optimizer. */
3722 tree
3724 {
3729 /* If this is a comparison, we can simply invert it, except for
3730 floating-point non-equality comparisons, in which case we just
3731 enclose a TRUTH_NOT_EXPR around what we have. */
3734 {
3737 && flag_trapping_math
3749 }
3752 {
3781 /* Here we can invert either operand. We invert the first operand
3782 unless the second operand is a TRUTH_NOT_EXPR in which case our
3783 result is the XOR of the first operand with the inside of the
3784 negation of the second operand. */
3789 else
3823 {
3834 /* A COND_EXPR may have a throw as one operand, which
3835 then has void type. Just leave void operands
3836 as they are. */
3843 }
3860 CASE_CONVERT:
3862 {
3865 }
3867 /* ... fall through ... */
3898 }
3904 }
3906 /* Return a simplified tree node for the truth-negation of ARG. This
3907 never alters ARG itself. We assume that ARG is an operation that
3908 returns a truth value (0 or 1).
3910 FIXME: one would think we would fold the result, but it causes
3911 problems with the dominator optimizer. */
3913 tree
3915 {
3916 tree tem;
3923 {
3926 }
3929 }
3931 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3932 operands are another bit-wise operation with a common input. If so,
3933 distribute the bit operations to save an operation and possibly two if
3934 constants are involved. For example, convert
3935 (A | B) & (A | C) into A | (B & C)
3936 Further simplification will occur if B and C are constants.
3938 If this optimization cannot be done, 0 will be returned. */
3940 static tree
3943 {
3944 tree common;
3954 {
3958 }
3960 {
3964 }
3966 {
3970 }
3972 {
3976 }
3977 else
3985 }
3987 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3988 with code CODE. This optimization is unsafe. */
3989 static tree
3992 {
3996 /* (A / C) +- (B / C) -> (A +- B) / C. */
4006 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
4011 {
4023 }
4026 }
4027 \f
4028 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4029 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
4031 static tree
4034 {
4038 {
4045 }
4060 }
4062 /* Optimize a bit-field compare.
4064 There are two cases: First is a compare against a constant and the
4065 second is a comparison of two items where the fields are at the same
4066 bit position relative to the start of a chunk (byte, halfword, word)
4067 large enough to contain it. In these cases we can avoid the shift
4068 implicit in bitfield extractions.
4070 For constants, we emit a compare of the shifted constant with the
4071 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4072 compared. For two fields at the same position, we do the ANDs with the
4073 similar mask and compare the result of the ANDs.
4075 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4076 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4077 are the left and right operands of the comparison, respectively.
4079 If the optimization described above can be done, we return the resulting
4080 tree. Otherwise we return zero. */
4082 static tree
4085 {
4094 tree mask;
4095 tree offset;
4097 /* Get all the information about the extractions being done. If the bit size
4098 if the same as the size of the underlying object, we aren't doing an
4099 extraction at all and so can do nothing. We also don't want to
4100 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4101 then will no longer be able to replace it. */
4109 {
4110 /* If this is not a constant, we can only do something if bit positions,
4111 sizes, and signedness are the same. */
4119 }
4121 /* See if we can find a mode to refer to this field. We should be able to,
4122 but fail if we can't. */
4131 /* Set signed and unsigned types of the precision of this mode for the
4132 shifts below. */
4136 /* Compute the bit position and size for the new reference and our offset
4137 within it. If the new reference is the same size as the original, we
4138 won't optimize anything, so return zero. */
4148 /* Make the mask to be used against the extracted field. */
4155 /* If not comparing with constant, just rework the comparison
4156 and return. */
4160 unsigned_type,
4163 mask),
4166 unsigned_type,
4169 mask));
4171 /* Otherwise, we are handling the constant case. See if the constant is too
4172 big for the field. Warn and return a tree of for 0 (false) if so. We do
4173 this not only for its own sake, but to avoid having to test for this
4174 error case below. If we didn't, we might generate wrong code.
4176 For unsigned fields, the constant shifted right by the field length should
4177 be all zero. For signed fields, the high-order bits should agree with
4178 the sign bit. */
4181 {
4186 {
4190 }
4191 }
4192 else
4193 {
4198 {
4202 }
4203 }
4205 /* Single-bit compares should always be against zero. */
4207 {
4210 }
4212 /* Make a new bitfield reference, shift the constant over the
4213 appropriate number of bits and mask it with the computed mask
4214 (in case this was a signed field). If we changed it, make a new one. */
4217 {
4220 }
4230 rhs);
4233 }
4234 \f
4235 /* Subroutine for fold_truthop: decode a field reference.
4237 If EXP is a comparison reference, we return the innermost reference.
4239 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4240 set to the starting bit number.
4242 If the innermost field can be completely contained in a mode-sized
4243 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4245 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4246 otherwise it is not changed.
4248 *PUNSIGNEDP is set to the signedness of the field.
4250 *PMASK is set to the mask used. This is either contained in a
4251 BIT_AND_EXPR or derived from the width of the field.
4253 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4255 Return 0 if this is not a component reference or is one that we can't
4256 do anything with. */
4258 static tree
4263 {
4267 tree unsigned_type;
4270 /* All the optimizations using this function assume integer fields.
4271 There are problems with FP fields since the type_for_size call
4272 below can fail for, e.g., XFmode. */
4276 /* We are interested in the bare arrangement of bits, so strip everything
4277 that doesn't affect the machine mode. However, record the type of the
4278 outermost expression if it may matter below. */
4285 {
4291 }
4300 /* If the number of bits in the reference is the same as the bitsize of
4301 the outer type, then the outer type gives the signedness. Otherwise
4302 (in case of a small bitfield) the signedness is unchanged. */
4306 /* Compute the mask to access the bitfield. */
4315 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4323 }
4325 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4326 bit positions. */
4328 static int
4330 {
4333 tree tmask;
4337 return
4344 }
4346 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4347 represents the sign bit of EXP's type. If EXP represents a sign
4348 or zero extension, also test VAL against the unextended type.
4349 The return value is the (sub)expression whose sign bit is VAL,
4350 or NULL_TREE otherwise. */
4352 static tree
4354 {
4358 tree t;
4360 /* Tree EXP must have an integral type. */
4365 /* Tree VAL must be an integer constant. */
4372 {
4379 }
4380 else
4381 {
4388 }
4390 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4391 treat VAL as if it were unsigned. */
4396 /* Handle extension from a narrower type. */
4402 }
4404 /* Subroutine for fold_truthop: determine if an operand is simple enough
4405 to be evaluated unconditionally. */
4407 static int
4409 {
4410 /* Strip any conversions that don't change the machine mode. */
4419 /* Don't regard global variables as simple. They may be
4420 allocated in ways unknown to the compiler (shared memory,
4421 #pragma weak, etc). */
4424 /* Loading a static variable is unduly expensive, but global
4425 registers aren't expensive. */
4427 }
4428 \f
4429 /* The following functions are subroutines to fold_range_test and allow it to
4430 try to change a logical combination of comparisons into a range test.
4432 For example, both
4433 X == 2 || X == 3 || X == 4 || X == 5
4434 and
4435 X >= 2 && X <= 5
4436 are converted to
4437 (unsigned) (X - 2) <= 3
4439 We describe each set of comparisons as being either inside or outside
4440 a range, using a variable named like IN_P, and then describe the
4441 range with a lower and upper bound. If one of the bounds is omitted,
4442 it represents either the highest or lowest value of the type.
4444 In the comments below, we represent a range by two numbers in brackets
4445 preceded by a "+" to designate being inside that range, or a "-" to
4446 designate being outside that range, so the condition can be inverted by
4447 flipping the prefix. An omitted bound is represented by a "-". For
4448 example, "- [-, 10]" means being outside the range starting at the lowest
4449 possible value and ending at 10, in other words, being greater than 10.
4450 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4451 always false.
4453 We set up things so that the missing bounds are handled in a consistent
4454 manner so neither a missing bound nor "true" and "false" need to be
4455 handled using a special case. */
4457 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4458 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4459 and UPPER1_P are nonzero if the respective argument is an upper bound
4460 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4461 must be specified for a comparison. ARG1 will be converted to ARG0's
4462 type if both are specified. */
4464 static tree
4467 {
4468 tree tem;
4472 /* If neither arg represents infinity, do the normal operation.
4473 Else, if not a comparison, return infinity. Else handle the special
4474 comparison rules. Note that most of the cases below won't occur, but
4475 are handled for consistency. */
4478 {
4483 }
4488 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4489 for neither. In real maths, we cannot assume open ended ranges are
4490 the same. But, this is computer arithmetic, where numbers are finite.
4491 We can therefore make the transformation of any unbounded range with
4492 the value Z, Z being greater than any representable number. This permits
4493 us to treat unbounded ranges as equal. */
4497 {
4518 }
4521 }
4522 \f
4523 /* Given EXP, a logical expression, set the range it is testing into
4524 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4525 actually being tested. *PLOW and *PHIGH will be made of the same
4526 type as the returned expression. If EXP is not a comparison, we
4527 will most likely not be returning a useful value and range. Set
4528 *STRICT_OVERFLOW_P to true if the return value is only valid
4529 because signed overflow is undefined; otherwise, do not change
4530 *STRICT_OVERFLOW_P. */
4532 tree
4535 {
4543 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4544 and see if we can refine the range. Some of the cases below may not
4545 happen, but it doesn't seem worth worrying about this. We "continue"
4546 the outer loop when we've changed something; otherwise we "break"
4547 the switch, which will "break" the while. */
4553 {
4558 {
4570 }
4573 {
4580 /* We can only do something if the range is testing for zero
4581 and if the second operand is an integer constant. Note that
4582 saying something is "in" the range we make is done by
4583 complementing IN_P since it will set in the initial case of
4584 being not equal to zero; "out" is leaving it alone. */
4591 {
4612 }
4614 /* If this is an unsigned comparison, we also know that EXP is
4615 greater than or equal to zero. We base the range tests we make
4616 on that fact, so we record it here so we can parse existing
4617 range tests. We test arg0_type since often the return type
4618 of, e.g. EQ_EXPR, is boolean. */
4620 {
4624 NULL_TREE))
4629 /* If the high bound is missing, but we have a nonzero low
4630 bound, reverse the range so it goes from zero to the low bound
4631 minus 1. */
4633 {
4638 }
4639 }
4645 /* (-x) IN [a,b] -> x in [-b, -a] */
4657 /* ~ X -> -X - 1 */
4667 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4668 move a constant to the other side. */
4673 /* If EXP is signed, any overflow in the computation is undefined,
4674 so we don't worry about it so long as our computations on
4675 the bounds don't overflow. For unsigned, overflow is defined
4676 and this is exactly the right thing. */
4688 /* Check for an unsigned range which has wrapped around the maximum
4689 value thus making n_high < n_low, and normalize it. */
4691 {
4697 /* If the range is of the form +/- [ x+1, x ], we won't
4698 be able to normalize it. But then, it represents the
4699 whole range or the empty set, so make it
4700 +/- [ -, - ]. */
4704 else
4706 }
4707 else
4731 /* If we're converting arg0 from an unsigned type, to exp,
4732 a signed type, we will be doing the comparison as unsigned.
4733 The tests above have already verified that LOW and HIGH
4734 are both positive.
4736 So we have to ensure that we will handle large unsigned
4737 values the same way that the current signed bounds treat
4738 negative values. */
4741 {
4742 tree high_positive;
4743 tree equiv_type;
4744 /* For fixed-point modes, we need to pass the saturating flag
4745 as the 2nd parameter. */
4750 else
4754 /* A range without an upper bound is, naturally, unbounded.
4755 Since convert would have cropped a very large value, use
4756 the max value for the destination type. */
4757 high_positive
4764 high_positive),
4767 /* If the low bound is specified, "and" the range with the
4768 range for which the original unsigned value will be
4769 positive. */
4771 {
4775 integer_zero_node),
4776 high_positive))
4780 }
4781 else
4782 {
4783 /* Otherwise, "or" the range with the range of the input
4784 that will be interpreted as negative. */
4788 integer_zero_node),
4789 high_positive))
4793 }
4794 }
4802 }
4805 }
4807 /* If EXP is a constant, we can evaluate whether this is true or false. */
4809 {
4816 }
4820 }
4821 \f
4822 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4823 type, TYPE, return an expression to test if EXP is in (or out of, depending
4824 on IN_P) the range. Return 0 if the test couldn't be created. */
4826 tree
4829 {
4832 #ifdef HAVE_canonicalize_funcptr_for_compare
4833 /* Disable this optimization for function pointer expressions
4834 on targets that require function pointer canonicalization. */
4839 #endif
4842 {
4848 }
4866 {
4868 {
4872 }
4874 }
4876 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4878 {
4880 HOST_WIDE_INT hi;
4885 {
4888 }
4889 else
4890 {
4893 }
4896 {
4898 {
4901 etype
4903 else
4906 }
4909 }
4910 }
4912 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4913 This requires wrap-around arithmetics for the type of the expression.
4914 First make sure that arithmetics in this type is valid, then make sure
4915 that it wraps around. */
4921 {
4924 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4925 for the type in question, as we rely on this here. */
4935 else
4937 }
4947 {
4949 {
4956 }
4958 }
4966 }
4967 \f
4968 /* Return the predecessor of VAL in its type, handling the infinite case. */
4970 static tree
4972 {
4978 else
4980 }
4982 /* Return the successor of VAL in its type, handling the infinite case. */
4984 static tree
4986 {
4992 else
4994 }
4996 /* Given two ranges, see if we can merge them into one. Return 1 if we
4997 can, 0 if we can't. Set the output range into the specified parameters. */
4999 bool
5002 {
5006 tree tem;
5016 /* Make range 0 be the range that starts first, or ends last if they
5017 start at the same value. Swap them if it isn't. */
5020 || (lowequal
5023 {
5027 }
5029 /* Now flag two cases, whether the ranges are disjoint or whether the
5030 second range is totally subsumed in the first. Note that the tests
5031 below are simplified by the ones above. */
5037 /* We now have four cases, depending on whether we are including or
5038 excluding the two ranges. */
5040 {
5041 /* If they don't overlap, the result is false. If the second range
5042 is a subset it is the result. Otherwise, the range is from the start
5043 of the second to the end of the first. */
5048 else
5050 }
5053 {
5054 /* If they don't overlap, the result is the first range. If they are
5055 equal, the result is false. If the second range is a subset of the
5056 first, and the ranges begin at the same place, we go from just after
5057 the end of the second range to the end of the first. If the second
5058 range is not a subset of the first, or if it is a subset and both
5059 ranges end at the same place, the range starts at the start of the
5060 first range and ends just before the second range.
5061 Otherwise, we can't describe this as a single range. */
5067 {
5072 {
5073 /* We are in the weird situation where high0 > high1 but
5074 high1 has no successor. Punt. */
5076 }
5077 }
5079 {
5084 {
5085 /* low0 < low1 but low1 has no predecessor. Punt. */
5087 }
5088 }
5089 else
5091 }
5094 {
5095 /* If they don't overlap, the result is the second range. If the second
5096 is a subset of the first, the result is false. Otherwise,
5097 the range starts just after the first range and ends at the
5098 end of the second. */
5103 else
5104 {
5109 {
5110 /* high1 > high0 but high0 has no successor. Punt. */
5112 }
5113 }
5114 }
5116 else
5117 {
5118 /* The case where we are excluding both ranges. Here the complex case
5119 is if they don't overlap. In that case, the only time we have a
5120 range is if they are adjacent. If the second is a subset of the
5121 first, the result is the first. Otherwise, the range to exclude
5122 starts at the beginning of the first range and ends at the end of the
5123 second. */
5125 {
5130 else
5131 {
5132 /* Canonicalize - [min, x] into - [-, x]. */
5135 {
5140 /* FALLTHROUGH */
5153 }
5155 /* Canonicalize - [x, max] into - [x, -]. */
5158 {
5163 /* FALLTHROUGH */
5178 }
5180 /* The ranges might be also adjacent between the maximum and
5181 minimum values of the given type. For
5182 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5183 return + [x + 1, y - 1]. */
5185 {
5192 }
5193 else
5195 }
5196 }
5199 else
5201 }
5205 }
5206 \f
5208 /* Subroutine of fold, looking inside expressions of the form
5209 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5210 of the COND_EXPR. This function is being used also to optimize
5211 A op B ? C : A, by reversing the comparison first.
5213 Return a folded expression whose code is not a COND_EXPR
5214 anymore, or NULL_TREE if no folding opportunity is found. */
5216 static tree
5219 {
5224 tree tem;
5229 /* If we have A op 0 ? A : -A, consider applying the following
5230 transformations:
5232 A == 0? A : -A same as -A
5233 A != 0? A : -A same as A
5234 A >= 0? A : -A same as abs (A)
5235 A > 0? A : -A same as abs (A)
5236 A <= 0? A : -A same as -abs (A)
5237 A < 0? A : -A same as -abs (A)
5239 None of these transformations work for modes with signed
5240 zeros. If A is +/-0, the first two transformations will
5241 change the sign of the result (from +0 to -0, or vice
5242 versa). The last four will fix the sign of the result,
5243 even though the original expressions could be positive or
5244 negative, depending on the sign of A.
5246 Note that all these transformations are correct if A is
5247 NaN, since the two alternatives (A and -A) are also NaNs. */
5254 /* In the case that A is of the form X-Y, '-A' (arg2) may
5255 have already been folded to Y-X, check for that. */
5263 {
5277 /* Fall through. */
5299 }
5301 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5302 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5303 both transformations are correct when A is NaN: A != 0
5304 is then true, and A == 0 is false. */
5308 {
5313 }
5315 /* Try some transformations of A op B ? A : B.
5317 A == B? A : B same as B
5318 A != B? A : B same as A
5319 A >= B? A : B same as max (A, B)
5320 A > B? A : B same as max (B, A)
5321 A <= B? A : B same as min (A, B)
5322 A < B? A : B same as min (B, A)
5324 As above, these transformations don't work in the presence
5325 of signed zeros. For example, if A and B are zeros of
5326 opposite sign, the first two transformations will change
5327 the sign of the result. In the last four, the original
5328 expressions give different results for (A=+0, B=-0) and
5329 (A=-0, B=+0), but the transformed expressions do not.
5331 The first two transformations are correct if either A or B
5332 is a NaN. In the first transformation, the condition will
5333 be false, and B will indeed be chosen. In the case of the
5334 second transformation, the condition A != B will be true,
5335 and A will be chosen.
5337 The conversions to max() and min() are not correct if B is
5338 a number and A is not. The conditions in the original
5339 expressions will be false, so all four give B. The min()
5340 and max() versions would give a NaN instead. */
5343 /* Avoid these transformations if the COND_EXPR may be used
5344 as an lvalue in the C++ front-end. PR c++/19199. */
5345 && (in_gimple_form
5350 {
5355 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5357 {
5361 }
5364 {
5373 /* In C++ a ?: expression can be an lvalue, so put the
5374 operand which will be used if they are equal first
5375 so that we can convert this back to the
5376 corresponding COND_EXPR. */
5378 {
5387 }
5394 {
5403 }
5418 }
5419 }
5421 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5422 we might still be able to simplify this. For example,
5423 if C1 is one less or one more than C2, this might have started
5424 out as a MIN or MAX and been transformed by this function.
5425 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5431 {
5435 /* We can replace A with C1 in this case. */
5440 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5441 MIN_EXPR, to preserve the signedness of the comparison. */
5443 OEP_ONLY_CONST)
5447 OEP_ONLY_CONST))
5448 {
5451 arg2));
5454 }
5458 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5459 as above. */
5461 OEP_ONLY_CONST)
5465 OEP_ONLY_CONST))
5466 {
5469 arg2));
5472 }
5476 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5477 MAX_EXPR, to preserve the signedness of the comparison. */
5479 OEP_ONLY_CONST)
5483 OEP_ONLY_CONST))
5484 {
5487 arg2));
5489 }
5493 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5495 OEP_ONLY_CONST)
5499 OEP_ONLY_CONST))
5500 {
5503 arg2));
5505 }
5511 }
5514 }
5517 \f
5518 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5519 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5520 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5521 false) >= 2)
5522 #endif
5524 /* EXP is some logical combination of boolean tests. See if we can
5525 merge it into some range test. Return the new tree if so. */
5527 static tree
5530 {
5538 tree tem;
5542 /* If this is an OR operation, invert both sides; we will invert
5543 again at the end. */
5547 /* If both expressions are the same, if we can merge the ranges, and we
5548 can build the range test, return it or it inverted. If one of the
5549 ranges is always true or always false, consider it to be the same
5550 expression as the other. */
5558 {
5562 }
5564 /* On machines where the branch cost is expensive, if this is a
5565 short-circuited branch and the underlying object on both sides
5566 is the same, make a non-short-circuit operation. */
5572 {
5573 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5574 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5575 which cases we can't do this. */
5577 {
5583 }
5587 {
5596 {
5599 WARN_STRICT_OVERFLOW_COMPARISON);
5605 }
5606 }
5607 }
5610 }
5611 \f
5612 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5613 bit value. Arrange things so the extra bits will be set to zero if and
5614 only if C is signed-extended to its full width. If MASK is nonzero,
5615 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5617 static tree
5619 {
5622 tree temp;
5627 /* We work by getting just the sign bit into the low-order bit, then
5628 into the high-order bit, then sign-extend. We then XOR that value
5629 with C. */
5633 /* We must use a signed type in order to get an arithmetic right shift.
5634 However, we must also avoid introducing accidental overflows, so that
5635 a subsequent call to integer_zerop will work. Hence we must
5636 do the type conversion here. At this point, the constant is either
5637 zero or one, and the conversion to a signed type can never overflow.
5638 We could get an overflow if this conversion is done anywhere else. */
5648 /* If necessary, convert the type back to match the type of C. */
5654 }
5655 \f
5656 /* Find ways of folding logical expressions of LHS and RHS:
5657 Try to merge two comparisons to the same innermost item.
5658 Look for range tests like "ch >= '0' && ch <= '9'".
5659 Look for combinations of simple terms on machines with expensive branches
5660 and evaluate the RHS unconditionally.
5662 For example, if we have p->a == 2 && p->b == 4 and we can make an
5663 object large enough to span both A and B, we can do this with a comparison
5664 against the object ANDed with the a mask.
5666 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5667 operations to do this with one comparison.
5669 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5670 function and the one above.
5672 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5673 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5675 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5676 two operands.
5678 We return the simplified tree or 0 if no optimization is possible. */
5680 static tree
5683 {
5684 /* If this is the "or" of two comparisons, we can do something if
5685 the comparisons are NE_EXPR. If this is the "and", we can do something
5686 if the comparisons are EQ_EXPR. I.e.,
5687 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5689 WANTED_CODE is this operation code. For single bit fields, we can
5690 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5691 comparison for one-bit fields. */
5713 /* Start by getting the comparison codes. Fail if anything is volatile.
5714 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5715 it were surrounded with a NE_EXPR. */
5724 {
5728 }
5731 {
5735 }
5746 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5749 {
5750 tree result;
5753 {
5758 }
5761 {
5767 }
5768 }
5773 /* If the RHS can be evaluated unconditionally and its operands are
5774 simple, it wins to evaluate the RHS unconditionally on machines
5775 with expensive branches. In this case, this isn't a comparison
5776 that can be merged. Avoid doing this if the RHS is a floating-point
5777 comparison since those can trap. */
5784 {
5785 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5791 {
5797 }
5799 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5805 {
5811 }
5814 {
5816 {
5819 }
5821 }
5822 }
5824 /* See if the comparisons can be merged. Then get all the parameters for
5825 each side. */
5849 /* It must be true that the inner operation on the lhs of each
5850 comparison must be the same if we are to be able to do anything.
5851 Then see if we have constants. If not, the same must be true for
5852 the rhs's. */
5863 else
5866 /* If either comparison code is not correct for our logical operation,
5867 fail. However, we can convert a one-bit comparison against zero into
5868 the opposite comparison against that bit being set in the field. */
5872 {
5874 {
5875 /* Make the left operand unsigned, since we are only interested
5876 in the value of one bit. Otherwise we are doing the wrong
5877 thing below. */
5880 }
5881 else
5883 }
5885 /* This is analogous to the code for l_const above. */
5887 {
5889 {
5892 }
5893 else
5895 }
5897 /* See if we can find a mode that contains both fields being compared on
5898 the left. If we can't, fail. Otherwise, update all constants and masks
5899 to be relative to a field of that size. */
5904 volatilep);
5914 {
5917 }
5925 {
5933 {
5937 }
5938 }
5940 {
5948 {
5952 }
5953 }
5955 /* If the right sides are not constant, do the same for it. Also,
5956 disallow this optimization if a size or signedness mismatch occurs
5957 between the left and right sides. */
5959 {
5962 /* Make sure the two fields on the right
5963 correspond to the left without being swapped. */
5971 volatilep);
5981 {
5984 }
5993 /* Make a mask that corresponds to both fields being compared.
5994 Do this for both items being compared. If the operands are the
5995 same size and the bits being compared are in the same position
5996 then we can do this by masking both and comparing the masked
5997 results. */
6001 {
6014 }
6016 /* There is still another way we can do something: If both pairs of
6017 fields being compared are adjacent, we may be able to make a wider
6018 field containing them both.
6020 Note that we still must mask the lhs/rhs expressions. Furthermore,
6021 the mask must be shifted to account for the shift done by
6022 make_bit_field_ref. */
6027 {
6028 tree type;
6042 /* Convert to the smaller type before masking out unwanted bits. */
6045 {
6047 {
6051 }
6053 {
6057 }
6058 }
6068 }
6071 }
6073 /* Handle the case of comparisons with constants. If there is something in
6074 common between the masks, those bits of the constants must be the same.
6075 If not, the condition is always false. Test for this to avoid generating
6076 incorrect code below. */
6081 {
6083 {
6086 }
6087 else
6088 {
6091 }
6092 }
6094 /* Construct the expression we will return. First get the component
6095 reference we will make. Unless the mask is all ones the width of
6096 that field, perform the mask operation. Then compare with the
6097 merged constant. */
6103 {
6106 }
6111 fold_truthop_exit:
6114 }
6115 \f
6116 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
6117 constant. */
6119 static tree
6122 {
6125 tree comp_const;
6126 tree minmax_const;
6128 tree inner;
6139 /* If something does not permit us to optimize, return the original tree. */
6147 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6148 and GT_EXPR, doing the rest with recursive calls using logical
6149 simplifications. */
6151 {
6153 {
6154 tree tem
6161 }
6164 return
6166 optimize_minmax_comparison
6168 optimize_minmax_comparison
6173 /* MAX (X, 0) == 0 -> X <= 0 */
6177 /* MAX (X, 0) == 5 -> X == 5 */
6181 /* MAX (X, 0) == -1 -> false */
6185 /* MIN (X, 0) == 0 -> X >= 0 */
6189 /* MIN (X, 0) == 5 -> false */
6192 else
6193 /* MIN (X, 0) == -1 -> X == -1 */
6198 /* MAX (X, 0) > 0 -> X > 0
6199 MAX (X, 0) > 5 -> X > 5 */
6203 /* MAX (X, 0) > -1 -> true */
6207 /* MIN (X, 0) > 0 -> false
6208 MIN (X, 0) > 5 -> false */
6211 else
6212 /* MIN (X, 0) > -1 -> X > -1 */
6217 }
6218 }
6219 \f
6220 /* T is an integer expression that is being multiplied, divided, or taken a
6221 modulus (CODE says which and what kind of divide or modulus) by a
6222 constant C. See if we can eliminate that operation by folding it with
6223 other operations already in T. WIDE_TYPE, if non-null, is a type that
6224 should be used for the computation if wider than our type.
6226 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6227 (X * 2) + (Y * 4). We must, however, be assured that either the original
6228 expression would not overflow or that overflow is undefined for the type
6229 in the language in question.
6231 If we return a non-null expression, it is an equivalent form of the
6232 original computation, but need not be in the original type.
6234 We set *STRICT_OVERFLOW_P to true if the return values depends on
6235 signed overflow being undefined. Otherwise we do not change
6236 *STRICT_OVERFLOW_P. */
6238 static tree
6241 {
6242 /* To avoid exponential search depth, refuse to allow recursion past
6243 three levels. Beyond that (1) it's highly unlikely that we'll find
6244 something interesting and (2) we've probably processed it before
6245 when we built the inner expression. */
6248 tree ret;
6253 depth++;
6255 depth--;
6258 }
6260 static tree
6263 {
6274 /* Don't deal with constants of zero here; they confuse the code below. */
6284 /* Note that we need not handle conditional operations here since fold
6285 already handles those cases. So just do arithmetic here. */
6287 {
6289 /* For a constant, we can always simplify if we are a multiply
6290 or (for divide and modulus) if it is a multiple of our constant. */
6298 /* If op0 is an expression ... */
6304 /* ... and has wrapping overflow, and its type is smaller
6305 than ctype, then we cannot pass through as widening. */
6311 /* ... or this is a truncation (t is narrower than op0),
6312 then we cannot pass through this narrowing. */
6315 /* ... or signedness changes for division or modulus,
6316 then we cannot pass through this conversion. */
6320 /* ... or has undefined overflow while the converted to
6321 type has not, we cannot do the operation in the inner type
6322 as that would introduce undefined overflow. */
6327 /* Pass the constant down and see if we can make a simplification. If
6328 we can, replace this expression with the inner simplification for
6329 possible later conversion to our or some other type. */
6334 code == MULT_EXPR
6336 strict_overflow_p))))
6341 /* If widening the type changes it from signed to unsigned, then we
6342 must avoid building ABS_EXPR itself as unsigned. */
6344 {
6348 {
6351 }
6353 }
6354 /* If the constant is negative, we cannot simplify this. */
6357 /* FALLTHROUGH */
6365 /* If widening the type changes the signedness, then we can't perform
6366 this optimization as that changes the result. */
6370 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6376 {
6383 }
6387 /* If the second operand is constant, this is a multiplication
6388 or floor division, by a power of two, so we can treat it that
6389 way unless the multiplier or divisor overflows. Signed
6390 left-shift overflow is implementation-defined rather than
6391 undefined in C90, so do not convert signed left shift into
6392 multiplication. */
6395 /* const_binop may not detect overflow correctly,
6396 so check for it explicitly here. */
6401 size_one_node,
6406 ctype,
6408 t1),
6413 /* See if we can eliminate the operation on both sides. If we can, we
6414 can return a new PLUS or MINUS. If we can't, the only remaining
6415 cases where we can do anything are if the second operand is a
6416 constant. */
6422 /* If not multiplication, we can only do this if both operands
6423 are divisible by c. */
6426 {
6431 }
6433 /* If this was a subtraction, negate OP1 and set it to be an addition.
6434 This simplifies the logic below. */
6441 /* If either OP1 or C are negative, this optimization is not safe for
6442 some of the division and remainder types while for others we need
6443 to change the code. */
6445 {
6453 }
6455 /* If it's a multiply or a division/modulus operation of a multiple
6456 of our constant, do the operation and verify it doesn't overflow. */
6459 {
6462 /* We allow the constant to overflow with wrapping semantics. */
6466 }
6467 else
6470 /* If we have an unsigned type is not a sizetype, we cannot widen
6471 the operation since it will change the result if the original
6472 computation overflowed. */
6478 /* If we were able to eliminate our operation from the first side,
6479 apply our operation to the second side and reform the PLUS. */
6483 /* The last case is if we are a multiply. In that case, we can
6484 apply the distributive law to commute the multiply and addition
6485 if the multiplication of the constants doesn't overflow. */
6491 op1);
6496 /* We have a special case here if we are doing something like
6497 (C * 8) % 4 since we know that's zero. */
6500 /* If the multiplication can overflow we cannot optimize this.
6501 ??? Until we can properly mark individual operations as
6502 not overflowing we need to treat sizetype special here as
6503 stor-layout relies on this opimization to make
6504 DECL_FIELD_BIT_OFFSET always a constant. */
6510 {
6513 }
6515 /* ... fall through ... */
6519 /* If we can extract our operation from the LHS, do so and return a
6520 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6521 do something only if the second operand is a constant. */
6535 /* If these are the same operation types, we can associate them
6536 assuming no overflow. */
6549 /* If these operations "cancel" each other, we have the main
6550 optimizations of this pass, which occur when either constant is a
6551 multiple of the other, in which case we replace this with either an
6552 operation or CODE or TCODE.
6554 If we have an unsigned type that is not a sizetype, we cannot do
6555 this since it will change the result if the original computation
6556 overflowed. */
6564 {
6566 {
6573 }
6575 {
6582 }
6583 }
6588 }
6591 }
6592 \f
6593 /* Return a node which has the indicated constant VALUE (either 0 or
6594 1), and is of the indicated TYPE. */
6596 tree
6598 {
6603 else
6605 }
6608 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6609 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6610 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6611 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6612 COND is the first argument to CODE; otherwise (as in the example
6613 given here), it is the second argument. TYPE is the type of the
6614 original expression. Return NULL_TREE if no simplification is
6615 possible. */
6617 static tree
6622 {
6629 /* This transformation is only worthwhile if we don't have to wrap
6630 arg in a SAVE_EXPR, and the operation can be simplified on at least
6631 one of the branches once its pushed inside the COND_EXPR. */
6636 {
6640 /* If this operand throws an expression, then it does not make
6641 sense to try to perform a logical or arithmetic operation
6642 involving it. */
6647 }
6648 else
6649 {
6654 }
6658 {
6662 else
6664 }
6666 {
6670 else
6672 }
6676 }
6678 \f
6679 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6681 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6682 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6683 ADDEND is the same as X.
6685 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6686 and finite. The problematic cases are when X is zero, and its mode
6687 has signed zeros. In the case of rounding towards -infinity,
6688 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6689 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6691 bool
6693 {
6697 /* Don't allow the fold with -fsignaling-nans. */
6701 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6705 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6710 /* The mode has signed zeros, and we have to honor their sign.
6711 In this situation, there is only one case we can return true for.
6712 X - 0 is the same as X unless rounding towards -infinity is
6713 supported. */
6715 }
6717 /* Subroutine of fold() that checks comparisons of built-in math
6718 functions against real constants.
6720 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6721 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6722 is the type of the result and ARG0 and ARG1 are the operands of the
6723 comparison. ARG1 must be a TREE_REAL_CST.
6725 The function returns the constant folded tree if a simplification
6726 can be made, and NULL_TREE otherwise. */
6728 static tree
6732 {
6733 REAL_VALUE_TYPE c;
6736 {
6742 {
6743 /* sqrt(x) < y is always false, if y is negative. */
6747 /* sqrt(x) > y is always true, if y is negative and we
6748 don't care about NaNs, i.e. negative values of x. */
6752 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6755 }
6757 {
6758 REAL_VALUE_TYPE c2;
6764 {
6765 /* sqrt(x) > y is x == +Inf, when y is very large. */
6770 /* sqrt(x) > y is always false, when y is very large
6771 and we don't care about infinities. */
6773 }
6775 /* sqrt(x) > c is the same as x > c*c. */
6778 }
6780 {
6781 REAL_VALUE_TYPE c2;
6787 {
6788 /* sqrt(x) < y is always true, when y is a very large
6789 value and we don't care about NaNs or Infinities. */
6793 /* sqrt(x) < y is x != +Inf when y is very large and we
6794 don't care about NaNs. */
6799 /* sqrt(x) < y is x >= 0 when y is very large and we
6800 don't care about Infinities. */
6805 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6814 dconst0)),
6817 c2)));
6818 }
6820 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6825 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6828 {
6833 dconst0)),
6836 c2)));
6837 }
6838 }
6839 }
6842 }
6844 /* Subroutine of fold() that optimizes comparisons against Infinities,
6845 either +Inf or -Inf.
6847 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6848 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6849 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6851 The function returns the constant folded tree if a simplification
6852 can be made, and NULL_TREE otherwise. */
6854 static tree
6857 {
6859 REAL_VALUE_TYPE max;
6860 tree temp;
6865 /* For negative infinity swap the sense of the comparison. */
6871 {
6873 /* x > +Inf is always false, if with ignore sNANs. */
6879 /* x <= +Inf is always true, if we don't case about NaNs. */
6883 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6886 {
6889 }
6894 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6900 /* x < +Inf is always equal to x <= DBL_MAX. */
6906 /* x != +Inf is always equal to !(x > DBL_MAX). */
6918 }
6921 }
6923 /* Subroutine of fold() that optimizes comparisons of a division by
6924 a nonzero integer constant against an integer constant, i.e.
6925 X/C1 op C2.
6927 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6928 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6929 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6931 The function returns the constant folded tree if a simplification
6932 can be made, and NULL_TREE otherwise. */
6934 static tree
6937 {
6942 HOST_WIDE_INT hpart;
6947 /* We have to do this the hard way to detect unsigned overflow.
6948 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6959 {
6964 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6972 }
6974 {
6978 {
6997 }
6998 }
6999 else
7000 {
7001 /* A negative divisor reverses the relational operators. */
7007 {
7026 }
7027 }
7030 {
7051 {
7054 }
7059 {
7062 }
7067 {
7070 }
7075 {
7078 }
7083 }
7086 }
7089 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7090 equality/inequality test, then return a simplified form of the test
7091 using a sign testing. Otherwise return NULL. TYPE is the desired
7092 result type. */
7094 static tree
7097 tree result_type)
7098 {
7099 /* If this is testing a single bit, we can optimize the test. */
7103 {
7104 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7105 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7109 /* This is only a win if casting to a signed type is cheap,
7110 i.e. when arg00's type is not a partial mode. */
7113 {
7116 result_type,
7119 }
7120 }
7123 }
7125 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7126 equality/inequality test, then return a simplified form of
7127 the test using shifts and logical operations. Otherwise return
7128 NULL. TYPE is the desired result type. */
7130 tree
7133 {
7134 /* If this is testing a single bit, we can optimize the test. */
7138 {
7147 /* First, see if we can fold the single bit test into a sign-bit
7148 test. */
7150 result_type);
7154 /* Otherwise we have (A & C) != 0 where C is a single bit,
7155 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7156 Similarly for (A & C) == 0. */
7158 /* If INNER is a right shift of a constant and it plus BITNUM does
7159 not overflow, adjust BITNUM and INNER. */
7166 {
7169 }
7171 /* If we are going to be able to omit the AND below, we must do our
7172 operations as unsigned. If we must use the AND, we have a choice.
7173 Normally unsigned is faster, but for some machines signed is. */
7174 #ifdef LOAD_EXTEND_OP
7177 #else
7179 #endif
7195 /* Put the AND last so it can combine with more things. */
7198 /* Make sure to return the proper type. */
7202 }
7204 }
7206 /* Check whether we are allowed to reorder operands arg0 and arg1,
7207 such that the evaluation of arg1 occurs before arg0. */
7209 static bool
7211 {
7218 }
7220 /* Test whether it is preferable two swap two operands, ARG0 and
7221 ARG1, for example because ARG0 is an integer constant and ARG1
7222 isn't. If REORDER is true, only recommend swapping if we can
7223 evaluate the operands in reverse order. */
7225 bool
7227 {
7263 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7264 for commutative and comparison operators. Ensuring a canonical
7265 form allows the optimizers to find additional redundancies without
7266 having to explicitly check for both orderings. */
7272 /* Put SSA_NAMEs last. */
7278 /* Put variables last. */
7285 }
7287 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7288 ARG0 is extended to a wider type. */
7290 static tree
7293 {
7295 tree arg1_unw;
7304 #ifdef HAVE_canonicalize_funcptr_for_compare
7305 /* Disable this optimization if we're casting a function pointer
7306 type on targets that require function pointer canonicalization. */
7311 #endif
7318 /* If possible, express the comparison in the shorter mode. */
7338 /* If we are comparing with the integer that does not fit into the range
7339 of the shorter type, the result is known. */
7350 {
7377 }
7380 }
7382 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7383 ARG0 just the signedness is changed. */
7385 static tree
7388 {
7389 tree arg0_inner;
7399 #ifdef HAVE_canonicalize_funcptr_for_compare
7400 /* Disable this optimization if we're casting a function pointer
7401 type on targets that require function pointer canonicalization. */
7406 #endif
7426 else
7430 }
7432 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7433 step of the array. Reconstructs s and delta in the case of s *
7434 delta being an integer constant (and thus already folded). ADDR is
7435 the address. MULT is the multiplicative expression. If the
7436 function succeeds, the new address expression is returned.
7437 Otherwise NULL_TREE is returned. LOC is the location of the
7438 resulting expression. */
7440 static tree
7442 {
7446 tree itype;
7449 /* Strip the nops that might be added when converting op1 to sizetype. */
7452 /* Canonicalize op1 into a possibly non-constant delta
7453 and an INTEGER_CST s. */
7455 {
7462 {
7465 }
7467 {
7470 }
7471 else
7473 }
7475 {
7478 }
7479 else
7480 {
7481 /* Simulate we are delta * 1. */
7484 }
7487 {
7489 {
7490 /* Remember if this was a multi-dimensional array. */
7503 {
7506 }
7507 else
7508 {
7509 /* Try if delta is a multiple of step. */
7514 }
7516 /* Only fold here if we can verify we do not overflow one
7517 dimension of a multi-dimensional array. */
7519 {
7520 tree tmp;
7536 }
7539 }
7540 else
7545 }
7547 /* We found the suitable array reference. So copy everything up to it,
7548 and replace the index. */
7556 {
7560 }
7568 }
7571 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7572 means A >= Y && A != MAX, but in this case we know that
7573 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7575 static tree
7577 {
7584 else
7593 {
7596 }
7598 {
7601 }
7602 else
7609 {
7610 /* Convert the pointer types into integer before taking the difference. */
7614 }
7615 else
7622 }
7624 /* Fold a sum or difference of at least one multiplication.
7625 Returns the folded tree or NULL if no simplification could be made. */
7627 static tree
7630 {
7634 /* (A * C) +- (B * C) -> (A+-B) * C.
7635 (A * C) +- A -> A * (C+-1).
7636 We are most concerned about the case where C is a constant,
7637 but other combinations show up during loop reduction. Since
7638 it is not difficult, try all four possibilities. */
7641 {
7644 }
7646 {
7649 }
7650 else
7651 {
7652 /* We cannot generate constant 1 for fract. */
7657 }
7659 {
7662 }
7664 {
7666 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7667 the purpose of this canonicalization. */
7671 {
7674 }
7675 else
7677 }
7678 else
7679 {
7680 /* We cannot generate constant 1 for fract. */
7685 }
7697 /* No identical multiplicands; see if we can find a common
7698 power-of-two factor in non-power-of-two multiplies. This
7699 can help in multi-dimensional array access. */
7702 {
7705 tree maybe_same;
7709 /* Move min of absolute values to int11. */
7712 {
7717 }
7718 else
7722 /* The remainder should not be a constant, otherwise we
7723 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7724 increased the number of multiplications necessary. */
7726 {
7734 }
7735 }
7745 }
7747 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7748 specified by EXPR into the buffer PTR of length LEN bytes.
7749 Return the number of bytes placed in the buffer, or zero
7750 upon failure. */
7752 static int
7754 {
7765 {
7769 else
7774 {
7781 else
7783 }
7784 else
7787 }
7789 }
7792 /* Subroutine of native_encode_expr. Encode the REAL_CST
7793 specified by EXPR into the buffer PTR of length LEN bytes.
7794 Return the number of bytes placed in the buffer, or zero
7795 upon failure. */
7797 static int
7799 {
7805 /* There are always 32 bits in each long, no matter the size of
7806 the hosts long. We handle floating point representations with
7807 up to 192 bits. */
7818 {
7823 {
7830 else
7832 }
7833 else
7836 }
7838 }
7840 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7841 specified by EXPR into the buffer PTR of length LEN bytes.
7842 Return the number of bytes placed in the buffer, or zero
7843 upon failure. */
7845 static int
7847 {
7849 tree part;
7860 }
7863 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7864 specified by EXPR into the buffer PTR of length LEN bytes.
7865 Return the number of bytes placed in the buffer, or zero
7866 upon failure. */
7868 static int
7870 {
7880 {
7882 {
7885 }
7886 else
7890 {
7893 }
7894 else
7895 {
7899 }
7901 }
7903 }
7906 /* Subroutine of native_encode_expr. Encode the STRING_CST
7907 specified by EXPR into the buffer PTR of length LEN bytes.
7908 Return the number of bytes placed in the buffer, or zero
7909 upon failure. */
7911 static int
7913 {
7915 HOST_WIDE_INT total_bytes;
7926 {
7930 }
7931 else
7934 }
7937 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7938 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7939 buffer PTR of length LEN bytes. Return the number of bytes
7940 placed in the buffer, or zero upon failure. */
7942 int
7944 {
7946 {
7964 }
7965 }
7968 /* Subroutine of native_interpret_expr. Interpret the contents of
7969 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7970 If the buffer cannot be interpreted, return NULL_TREE. */
7972 static tree
7974 {
7988 {
7991 {
7998 else
8000 }
8001 else
8007 else
8010 }
8013 }
8016 /* Subroutine of native_interpret_expr. Interpret the contents of
8017 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8018 If the buffer cannot be interpreted, return NULL_TREE. */
8020 static tree
8022 {
8027 /* There are always 32 bits in each long, no matter the size of
8028 the hosts long. We handle floating point representations with
8029 up to 192 bits. */
8030 REAL_VALUE_TYPE r;
8041 {
8044 {
8051 else
8053 }
8054 else
8059 }
8063 }
8066 /* Subroutine of native_interpret_expr. Interpret the contents of
8067 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8068 If the buffer cannot be interpreted, return NULL_TREE. */
8070 static tree
8072 {
8087 }
8090 /* Subroutine of native_interpret_expr. Interpret the contents of
8091 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8092 If the buffer cannot be interpreted, return NULL_TREE. */
8094 static tree
8096 {
8108 {
8113 }
8115 }
8118 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8119 the buffer PTR of length LEN as a constant of type TYPE. For
8120 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8121 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8122 return NULL_TREE. */
8124 tree
8126 {
8128 {
8145 }
8146 }
8149 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
8150 TYPE at compile-time. If we're unable to perform the conversion
8151 return NULL_TREE. */
8153 static tree
8155 {
8156 /* We support up to 512-bit values (for V8DFmode). */
8160 /* Check that the host and target are sane. */
8169 }
8171 /* Build an expression for the address of T. Folds away INDIRECT_REF
8172 to avoid confusing the gimplify process. */
8174 tree
8176 {
8177 /* The size of the object is not relevant when talking about its address. */
8181 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8184 {
8188 {
8191 }
8192 }
8194 {
8199 }
8200 else
8201 {
8204 }
8207 }
8209 /* Build an expression for the address of T. */
8211 tree
8213 {
8217 }
8219 /* Fold a unary expression of code CODE and type TYPE with operand
8220 OP0. Return the folded expression if folding is successful.
8221 Otherwise, return NULL_TREE. */
8223 tree
8225 {
8226 tree tem;
8227 tree arg0;
8235 {
8238 {
8239 /* Don't use STRIP_NOPS, because signedness of argument type
8240 matters. */
8242 }
8243 else
8244 {
8245 /* Strip any conversions that don't change the mode. This
8246 is safe for every expression, except for a comparison
8247 expression because its signedness is derived from its
8248 operands.
8250 Note that this is done as an internal manipulation within
8251 the constant folder, in order to find the simplest
8252 representation of the arguments so that their form can be
8253 studied. In any cases, the appropriate type conversions
8254 should be put back in the tree that will get out of the
8255 constant folder. */
8257 }
8258 }
8261 {
8268 {
8282 /* If this was a conversion, and all we did was to move into
8283 inside the COND_EXPR, bring it back out. But leave it if
8284 it is a conversion from integer to integer and the
8285 result precision is no wider than a word since such a
8286 conversion is cheap and may be optimized away by combine,
8287 while it couldn't if it were outside the COND_EXPR. Then return
8288 so we don't get into an infinite recursion loop taking the
8289 conversion out and then back in. */
8301 && (INTEGRAL_TYPE_P
8305 {
8314 }
8316 }
8318 {
8320 {
8324 }
8328 integer_one_node),
8330 integer_zero_node));
8331 }
8332 }
8335 {
8337 /* Re-association barriers around constants and other re-association
8338 barriers can be removed. */
8344 CASE_CONVERT:
8350 /* If we have (type) (a CMP b) and type is an integral type, return
8351 new expression involving the new type. */
8356 /* Handle cases of two conversions in a row. */
8358 {
8380 /* In addition to the cases of two conversions in a row
8381 handled below, if we are converting something to its own
8382 type via an object of identical or wider precision, neither
8383 conversion is needed. */
8390 /* Likewise, if the intermediate and initial types are either both
8391 float or both integer, we don't need the middle conversion if the
8392 former is wider than the latter and doesn't change the signedness
8393 (for integers). Avoid this if the final type is a pointer since
8394 then we sometimes need the middle conversion. Likewise if the
8395 final type has a precision not equal to the size of its mode. */
8404 && ! final_ptr
8408 /* If we have a sign-extension of a zero-extended value, we can
8409 replace that by a single zero-extension. */
8415 /* Two conversions in a row are not needed unless:
8416 - some conversion is floating-point (overstrict for now), or
8417 - some conversion is a vector (overstrict for now), or
8418 - the intermediate type is narrower than both initial and
8419 final, or
8420 - the intermediate type and innermost type differ in signedness,
8421 and the outermost type is wider than the intermediate, or
8422 - the initial type is a pointer type and the precisions of the
8423 intermediate and final types differ, or
8424 - the final type is a pointer type and the precisions of the
8425 initial and intermediate types differ. */
8439 }
8441 /* Handle (T *)&A.B.C for A being of type T and B and C
8442 living at offset zero. This occurs frequently in
8443 C++ upcasting and then accessing the base. */
8447 {
8449 tree offset;
8455 /* If the reference was to a (constant) zero offset, we can use
8456 the address of the base if it has the same base type
8457 as the result type. */
8463 }
8467 /* Detect assigning a bitfield. */
8469 && DECL_BIT_FIELD
8471 {
8472 /* Don't leave an assignment inside a conversion
8473 unless assigning a bitfield. */
8475 /* First do the assignment, then return converted constant. */
8481 }
8483 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8484 constants (if x has signed type, the sign bit cannot be set
8485 in c). This folds extension into the BIT_AND_EXPR.
8486 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8487 very likely don't have maximal range for their precision and this
8488 transformation effectively doesn't preserve non-maximal ranges. */
8492 {
8503 <= HOST_BITS_PER_WIDE_INT
8505 {
8512 #ifdef LOAD_EXTEND_OP
8514 && !flag_syntax_only
8517 {
8521 }
8522 #endif
8523 }
8525 {
8531 }
8532 }
8534 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8535 when one of the new casts will fold away. Conservatively we assume
8536 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8542 {
8550 }
8552 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8553 of the same precision, and X is an integer type not narrower than
8554 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8560 {
8566 }
8568 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8569 type of X and Y (integer types only). */
8574 {
8575 /* Be careful not to introduce new overflows. */
8576 tree mult_type;
8579 else
8583 {
8590 }
8591 }
8607 /* For integral conversions with the same precision or pointer
8608 conversions use a NOP_EXPR instead. */
8616 /* Strip inner integral conversions that do not change the precision. */
8640 /* Convert fabs((double)float) into (double)fabsf(float). */
8643 {
8649 targ0));
8650 }
8651 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8657 /* Strip sign ops from argument. */
8659 {
8664 }
8671 {
8677 }
8679 {
8684 }
8694 /* Convert ~ (-A) to A - 1. */
8699 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8708 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8723 /* Perform BIT_NOT_EXPR on each element individually. */
8725 {
8730 {
8732 {
8738 }
8739 else
8742 }
8745 }
8750 /* The argument to invert_truthvalue must have Boolean type. */
8754 /* Note that the operand of this must be an int
8755 and its values must be 0 or 1.
8756 ("true" is a fixed value perhaps depending on the language,
8757 but we don't handle values other than 1 correctly yet.) */
8772 {
8780 }
8782 {
8787 }
8789 {
8793 {
8802 }
8803 }
8815 {
8823 }
8825 {
8829 }
8831 {
8835 {
8844 }
8845 }
8851 }
8854 /* If the operation was a conversion do _not_ mark a resulting constant
8855 with TREE_OVERFLOW if the original constant was not. These conversions
8856 have implementation defined behavior and retaining the TREE_OVERFLOW
8857 flag here would confuse later passes such as VRP. */
8858 tree
8861 {
8870 }
8872 /* Fold a binary expression of code CODE and type TYPE with operands
8873 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8874 Return the folded expression if folding is successful. Otherwise,
8875 return NULL_TREE. */
8877 static tree
8879 {
8886 else
8889 /* MIN (MAX (a, b), b) == b. */
8894 /* MIN (MAX (b, a), b) == b. */
8900 /* MIN (a, MAX (a, b)) == a. */
8906 /* MIN (a, MAX (b, a)) == a. */
8913 }
8915 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8916 by changing CODE to reduce the magnitude of constants involved in
8917 ARG0 of the comparison.
8918 Returns a canonicalized comparison tree if a simplification was
8919 possible, otherwise returns NULL_TREE.
8920 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8921 valid if signed overflow is undefined. */
8923 static tree
8927 {
8933 /* Match A +- CST code arg1 and CST code arg1. We can change the
8934 first form only if overflow is undefined. */
8936 /* In principle pointers also have undefined overflow behavior,
8937 but that causes problems elsewhere. */
8945 /* Identify the constant in arg0 and its sign. */
8948 else
8952 /* Overflowed constants and zero will cause problems. */
8957 /* See if we can reduce the magnitude of the constant in
8958 arg0 by changing the comparison code. */
8960 {
8961 /* CST <= arg1 -> CST-1 < arg1. */
8964 /* -CST < arg1 -> -CST-1 <= arg1. */
8967 /* CST > arg1 -> CST-1 >= arg1. */
8970 /* -CST >= arg1 -> -CST-1 > arg1. */
8973 else
8975 /* arg1 code' CST' might be more canonical. */
8977 }
8978 else
8979 {
8980 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8984 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8988 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8992 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8996 else
8999 }
9001 /* Now build the constant reduced in magnitude. But not if that
9002 would produce one outside of its types range. */
9010 /* We cannot swap the comparison here as that would cause us to
9011 endlessly recurse. */
9019 /* If swapping might yield to a more canonical form, do so. */
9022 else
9024 }
9026 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9027 overflow further. Try to decrease the magnitude of constants involved
9028 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9029 and put sole constants at the second argument position.
9030 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9032 static tree
9035 {
9036 tree t;
9041 /* Try canonicalization by simplifying arg0. */
9046 {
9050 }
9052 /* Try canonicalization by simplifying arg1 using the swapped
9053 comparison. */
9061 }
9063 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9064 space. This is used to avoid issuing overflow warnings for
9065 expressions like &p->x which can not wrap. */
9067 static bool
9069 {
9080 {
9083 }
9086 else
9087 {
9090 }
9105 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9106 array. */
9108 {
9109 HOST_WIDE_INT base_size;
9114 }
9117 }
9119 /* Subroutine of fold_binary. This routine performs all of the
9120 transformations that are common to the equality/inequality
9121 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9122 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9123 fold_binary should call fold_binary. Fold a comparison with
9124 tree code CODE and type TYPE with operands OP0 and OP1. Return
9125 the folded comparison or NULL_TREE. */
9127 static tree
9130 {
9143 /* If one arg is a real or integer constant, put it last. */
9147 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
9154 {
9158 tree lhs;
9165 /* If the constant operation overflowed this can be
9166 simplified as a comparison against INT_MAX/INT_MIN. */
9169 {
9173 /* Get the sign of the constant on the lhs if the
9174 operation were VARIABLE + CONST1. */
9178 /* The sign of the constant determines if we overflowed
9179 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9180 Canonicalize to the INT_MIN overflow by swapping the comparison
9181 if necessary. */
9185 /* We now can look at the canonicalized case
9186 VARIABLE + 1 CODE2 INT_MIN
9187 and decide on the result. */
9196 }
9201 {
9203 "when changing X +- C1 cmp C2 to "
9205 WARN_STRICT_OVERFLOW_COMPARISON);
9207 }
9208 }
9210 /* For comparisons of pointers we can decompose it to a compile time
9211 comparison of the base objects and the offsets into the object.
9212 This requires at least one operand being an ADDR_EXPR or a
9213 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9219 {
9226 /* Get base and offset for the access. Strip ADDR_EXPR for
9227 get_inner_reference, but put it back by stripping INDIRECT_REF
9228 off the base object if possible. indirect_baseN will be true
9229 if baseN is not an address but refers to the object itself. */
9232 {
9238 else
9240 }
9242 {
9245 }
9249 {
9255 else
9257 }
9259 {
9262 }
9264 /* If we have equivalent bases we might be able to simplify. */
9267 {
9268 /* We can fold this expression to a constant if the non-constant
9269 offset parts are equal. */
9277 {
9284 "occur when comparing P +- C1 with "
9286 WARN_STRICT_OVERFLOW_CONDITIONAL);
9289 {
9303 }
9304 }
9305 /* We can simplify the comparison to a comparison of the variable
9306 offset parts if the constant offset parts are equal.
9307 Be careful to use signed size type here because otherwise we
9308 mess with array offsets in the wrong way. This is possible
9309 because pointer arithmetic is restricted to retain within an
9310 object and overflow on pointer differences is undefined as of
9311 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9315 {
9316 tree signed_size_type_node;
9319 /* By converting to signed size type we cover middle-end pointer
9320 arithmetic which operates on unsigned pointer types of size
9321 type size and ARRAY_REF offsets which are properly sign or
9322 zero extended from their type in case it is narrower than
9323 size type. */
9326 else
9328 offset0);
9331 else
9333 offset1);
9340 "occur when comparing P +- C1 with "
9342 WARN_STRICT_OVERFLOW_COMPARISON);
9345 }
9346 }
9347 /* For non-equal bases we can simplify if they are addresses
9348 of local binding decls or constants. */
9350 /* We know that !operand_equal_p (base0, base1, 0)
9351 because the if condition was false. But make
9352 sure two decls are not the same. */
9366 {
9373 }
9374 /* For equal offsets we can simplify to a comparison of the
9375 base addresses. */
9377 && (indirect_base0
9379 && (indirect_base1
9384 {
9390 }
9391 }
9393 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9394 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9395 the resulting offset is smaller in absolute value than the
9396 original one. */
9404 {
9409 tree cst;
9411 "occur when combining constants around "
9414 /* Put the constant on the side where it doesn't overflow and is
9415 of lower absolute value than before. */
9421 {
9424 variable1,
9428 }
9435 {
9440 variable2);
9441 }
9442 }
9444 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9445 signed arithmetic case. That form is created by the compiler
9446 often enough for folding it to be of value. One example is in
9447 computing loop trip counts after Operator Strength Reduction. */
9453 {
9462 "eliminating multiplication in comparison "
9464 WARN_STRICT_OVERFLOW_COMPARISON);
9466 /* If const1 is negative we swap the sense of the comparison. */
9471 }
9478 {
9486 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9492 /* (-a) CMP (-b) -> b CMP a */
9499 {
9500 REAL_VALUE_TYPE cst;
9503 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9510 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9511 /* a CMP (-0) -> a CMP 0 */
9516 /* x != NaN is always true, other ops are always false. */
9519 {
9522 }
9524 /* Fold comparisons against infinity. */
9527 {
9531 }
9532 }
9534 /* If this is a comparison of a real constant with a PLUS_EXPR
9535 or a MINUS_EXPR of a real constant, we can convert it into a
9536 comparison with a revised real constant as long as no overflow
9537 occurs when unsafe_math_optimizations are enabled. */
9549 /* Likewise, we can simplify a comparison of a real constant with
9550 a MINUS_EXPR whose first operand is also a real constant, i.e.
9551 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9552 floating-point types only if -fassociative-math is set. */
9563 /* Fold comparisons against built-in math functions. */
9565 && flag_unsafe_math_optimizations
9567 {
9571 {
9575 }
9576 }
9577 }
9581 {
9582 /* If we are widening one operand of an integer comparison,
9583 see if the other operand is similarly being widened. Perhaps we
9584 can do the comparison in the narrower type. */
9589 /* Or if we are changing signedness. */
9593 }
9595 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9596 constant, we can simplify it. */
9601 {
9605 }
9607 /* Simplify comparison of something with itself. (For IEEE
9608 floating-point, we can only do some of these simplifications.) */
9610 {
9612 {
9627 /* For NE, we can only do this simplification if integer
9628 or we don't honor IEEE floating point NaNs. */
9632 /* ... fall through ... */
9638 }
9639 }
9641 /* If we are comparing an expression that just has comparisons
9642 of two integer values, arithmetic expressions of those comparisons,
9643 and constants, we can simplify it. There are only three cases
9644 to check: the two values can either be equal, the first can be
9645 greater, or the second can be greater. Fold the expression for
9646 those three values. Since each value must be 0 or 1, we have
9647 eight possibilities, each of which corresponds to the constant 0
9648 or 1 or one of the six possible comparisons.
9650 This handles common cases like (a > b) == 0 but also handles
9651 expressions like ((x > y) - (y > x)) > 0, which supposedly
9652 occur in macroized code. */
9655 {
9660 /* Don't handle degenerate cases here; they should already
9661 have been handled anyway. */
9670 {
9674 /* We can't just pass T to eval_subst in case cval1 or cval2
9675 was the same as ARG1. */
9677 tree high_result
9681 arg1);
9682 tree equal_result
9686 arg1);
9687 tree low_result
9691 arg1);
9693 /* All three of these results should be 0 or 1. Confirm they are.
9694 Then use those values to select the proper code to use. */
9699 {
9700 /* Make a 3-bit mask with the high-order bit being the
9701 value for `>', the next for '=', and the low for '<'. */
9705 {
9707 /* Always false. */
9728 /* Always true. */
9730 }
9733 {
9737 }
9739 }
9740 }
9741 }
9743 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9744 into a single range test. */
9752 {
9756 }
9758 /* Fold ~X op ~Y as Y op X. */
9761 {
9767 }
9769 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9772 {
9778 }
9781 }
9784 /* Subroutine of fold_binary. Optimize complex multiplications of the
9785 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9786 argument EXPR represents the expression "z" of type TYPE. */
9788 static tree
9790 {
9795 {
9798 }
9800 {
9803 }
9804 else
9805 {
9809 }
9818 }
9821 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9822 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9823 guarantees that P and N have the same least significant log2(M) bits.
9824 N is not otherwise constrained. In particular, N is not normalized to
9825 0 <= N < M as is common. In general, the precise value of P is unknown.
9826 M is chosen as large as possible such that constant N can be determined.
9828 Returns M and sets *RESIDUE to N.
9830 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9831 account. This is not always possible due to PR 35705.
9832 */
9834 static unsigned HOST_WIDE_INT
9837 {
9844 {
9847 {
9849 tree offset;
9857 {
9860 else
9861 /* We don't handle more complicated offset expressions. */
9863 }
9864 }
9869 }
9871 {
9879 allow_func_align);
9885 {
9888 }
9890 {
9893 {
9896 /* Compute the greatest power-of-2 divisor of op1. */
9900 /* If align is non-zero and less than *modulus, replace
9901 *modulus with align., If align is 0, then either op1 is 0
9902 or the greatest power-of-2 divisor of op1 doesn't fit in an
9903 unsigned HOST_WIDE_INT. In either case, no additional
9904 constraint is imposed. */
9909 }
9910 }
9911 }
9913 /* If we get here, we were unable to determine anything useful about the
9914 expression. */
9916 }
9919 /* Fold a binary expression of code CODE and type TYPE with operands
9920 OP0 and OP1. LOC is the location of the resulting expression.
9921 Return the folded expression if folding is successful. Otherwise,
9922 return NULL_TREE. */
9924 tree
9927 {
9941 /* Strip any conversions that don't change the mode. This is
9942 safe for every expression, except for a comparison expression
9943 because its signedness is derived from its operands. So, in
9944 the latter case, only strip conversions that don't change the
9945 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9946 preserved.
9948 Note that this is done as an internal manipulation within the
9949 constant folder, in order to find the simplest representation
9950 of the arguments so that their form can be studied. In any
9951 cases, the appropriate type conversions should be put back in
9952 the tree that will get out of the constant folder. */
9955 {
9958 }
9959 else
9960 {
9963 }
9965 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9966 constant but we can't do arithmetic on them. */
9973 {
9975 {
9976 /* Make sure type and arg0 have the same saturating flag. */
9980 }
9983 else
9987 {
9991 }
9992 }
9994 /* If this is a commutative operation, and ARG0 is a constant, move it
9995 to ARG1 to reduce the number of tests below. */
10000 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10002 First check for cases where an arithmetic operation is applied to a
10003 compound, conditional, or comparison operation. Push the arithmetic
10004 operation inside the compound or conditional to see if any folding
10005 can then be done. Convert comparison to conditional for this purpose.
10006 The also optimizes non-constant cases that used to be done in
10007 expand_expr.
10009 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10010 one of the operands is a comparison and the other is a comparison, a
10011 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10012 code below would make the expression more complex. Change it to a
10013 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10014 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10026 {
10030 boolean_type_node,
10038 }
10042 {
10044 {
10051 }
10054 {
10061 }
10064 {
10070 }
10073 {
10079 }
10080 }
10083 {
10085 /* 0 +p index -> (type)index */
10089 /* PTR +p 0 -> PTR */
10093 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10099 arg1),
10101 arg0)));
10103 /* index +p PTR -> PTR +p index */
10110 /* (PTR +p B) +p A -> PTR +p (B + A) */
10112 {
10113 tree inner;
10122 }
10124 /* PTR_CST +p CST -> CST1 */
10129 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10130 of the array. Loop optimizer sometimes produce this type of
10131 expressions. */
10133 {
10138 }
10143 /* A + (-B) -> A - B */
10149 /* (-A) + B -> B - A */
10158 {
10159 /* Convert ~A + 1 to -A. */
10166 /* ~X + X is -1. */
10169 {
10174 {
10177 }
10178 }
10180 /* X + ~X is -1. */
10183 {
10188 {
10191 }
10192 }
10194 /* X + (X / CST) * -CST is X % CST. */
10199 {
10208 cst0));
10209 }
10210 }
10212 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
10213 same or one. Make sure type is not saturating.
10214 fold_plusminus_mult_expr will re-associate. */
10219 {
10223 }
10226 {
10230 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10231 with a constant, and the two constants have no bits in common,
10232 we should treat this as a BIT_IOR_EXPR since this may produce more
10233 simplifications. */
10241 {
10244 }
10246 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10247 (plus (plus (mult) (mult)) (foo)) so that we can
10248 take advantage of the factoring cases below. */
10255 {
10261 else
10274 parg0),
10276 marg)),
10280 return
10286 parg1)));
10287 }
10288 }
10289 else
10290 {
10291 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10295 /* Likewise if the operands are reversed. */
10299 /* Convert X + -C into X - C. */
10302 {
10308 }
10310 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10311 to __complex__ ( x, y ). This is not the same for SNaNs or
10312 if signed zeros are involved. */
10316 {
10323 {
10327 {
10333 }
10335 {
10341 }
10342 }
10343 }
10351 /* Convert x+x into x*2.0. */
10357 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10358 We associate floats only if the user has specified
10359 -fassociative-math. */
10363 {
10368 {
10369 tree tree0;
10372 }
10373 }
10374 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10375 We associate floats only if the user has specified
10376 -fassociative-math. */
10380 {
10385 {
10386 tree tree0;
10389 }
10390 }
10391 }
10393 bit_rotate:
10394 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10395 is a rotate of A by C1 bits. */
10396 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10397 is a rotate of A by B bits. */
10398 {
10400 tree rtype;
10409 /* Only create rotates in complete modes. Other cases are not
10410 expanded properly. */
10412 {
10428 {
10432 code0 == LSHIFT_EXPR
10436 }
10438 {
10446 TYPE_PRECISION
10450 return
10453 ? LROTATE_EXPR
10457 }
10459 {
10467 TYPE_PRECISION
10471 return fold_convert_loc
10474 ? LROTATE_EXPR
10478 }
10479 }
10480 }
10482 associate:
10483 /* In most languages, can't associate operations on floats through
10484 parentheses. Rather than remember where the parentheses were, we
10485 don't associate floats at all, unless the user has specified
10486 -fassociative-math.
10487 And, we need to make sure type is not saturating. */
10491 {
10496 /* Split both trees into variables, constants, and literals. Then
10497 associate each group together, the constants with literals,
10498 then the result with variables. This increases the chances of
10499 literals being recombined later and of generating relocatable
10500 expressions for the sum of a constant and literal. */
10505 /* With undefined overflow we can only associate constants
10506 with one variable. */
10510 {
10518 /* The only case we can still associate with two variables
10519 is if they are the same, modulo negation. */
10522 }
10524 /* Only do something if we found more than two objects. Otherwise,
10525 nothing has changed and we risk infinite recursion. */
10531 {
10532 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10541 /* Preserve the MINUS_EXPR if the negative part of the literal is
10542 greater than the positive part. Otherwise, the multiplicative
10543 folding code (i.e extract_muldiv) may be fooled in case
10544 unsigned constants are subtracted, like in the following
10545 example: ((X*2 + 4) - 8U)/2. */
10547 {
10551 {
10555 }
10556 else
10557 {
10561 }
10562 }
10564 {
10566 return
10570 else
10571 {
10574 return
10578 }
10579 }
10582 return
10585 }
10586 }
10591 /* Pointer simplifications for subtraction, simple reassociations. */
10593 {
10594 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10597 {
10607 }
10608 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10610 {
10617 }
10618 }
10619 /* A - (-B) -> A + B */
10624 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10635 /* Convert -A - 1 to ~A. */
10644 /* Convert -1 - A to ~A. */
10650 /* X - (X / CST) * CST is X % CST. */
10658 return
10664 {
10670 /* Fold A - (A & B) into ~B & A. */
10673 {
10675 {
10682 }
10684 {
10691 }
10692 }
10694 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10695 any power of 2 minus 1. */
10700 {
10706 {
10710 }
10711 }
10712 }
10714 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10718 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10719 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10720 (-ARG1 + ARG0) reduces to -ARG1. */
10724 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10725 __complex__ ( x, -y ). This is not the same for SNaNs or if
10726 signed zeros are involved. */
10730 {
10737 {
10741 {
10743 arg1r ? arg1r
10748 }
10750 {
10754 arg1i ? arg1i
10757 }
10758 }
10759 }
10761 /* Fold &x - &x. This can happen from &x.foo - &x.
10762 This is unsafe for certain floats even in non-IEEE formats.
10763 In IEEE, it is unsafe because it does wrong for NaNs.
10764 Also note that operand_equal_p is always false if an operand
10765 is volatile. */
10771 /* A - B -> A + (-B) if B is easily negatable. */
10774 /* Avoid this transformation if B is a positive REAL_CST. */
10783 /* Try folding difference of addresses. */
10784 {
10785 HOST_WIDE_INT diff;
10791 }
10793 /* Fold &a[i] - &a[j] to i-j. */
10798 {
10803 {
10811 }
10812 }
10815 && flag_unsafe_math_optimizations
10821 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10822 same or one. Make sure type is not saturating.
10823 fold_plusminus_mult_expr will re-associate. */
10828 {
10832 }
10837 /* (-A) * (-B) -> A * B */
10852 {
10857 /* Transform x * -1 into -x. Make sure to do the negation
10858 on the original operand with conversions not stripped
10859 because we can only strip non-sign-changing conversions. */
10862 /* Transform x * -C into -x * C if x is easily negatable. */
10871 tem);
10873 /* (a * (1 << b)) is (a << b) */
10883 /* (A + A) * C -> A * 2 * C */
10899 {
10902 "occur when simplifying "
10904 WARN_STRICT_OVERFLOW_MISC);
10906 }
10908 /* Optimize z * conj(z) for integer complex numbers. */
10915 }
10916 else
10917 {
10918 /* Maybe fold x * 0 to 0. The expressions aren't the same
10919 when x is NaN, since x * 0 is also NaN. Nor are they the
10920 same in modes with signed zeros, since multiplying a
10921 negative value by 0 gives -0, not +0. */
10926 /* In IEEE floating point, x*1 is not equivalent to x for snans.
10927 Likewise for complex arithmetic with signed zeros. */
10934 /* Transform x * -1.0 into -x. */
10941 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10942 the result for floating point types due to rounding so it is applied
10943 only if -fassociative-math was specify. */
10948 {
10954 }
10956 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10958 {
10961 {
10964 }
10965 }
10967 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10968 This is not the same for NaNs or if signed zeros are
10969 involved. */
10975 {
10978 return
10984 return
10989 }
10991 /* Optimize z * conj(z) for floating point complex numbers.
10992 Guarded by flag_unsafe_math_optimizations as non-finite
10993 imaginary components don't produce scalar results. */
11004 {
11008 /* Optimizations of root(...)*root(...). */
11010 {
11015 /* Optimize sqrt(x)*sqrt(x) as x. */
11021 /* Optimize root(x)*root(y) as root(x*y). */
11025 }
11027 /* Optimize expN(x)*expN(y) as expN(x+y). */
11029 {
11035 }
11037 /* Optimizations of pow(...)*pow(...). */
11041 {
11047 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11049 {
11054 }
11056 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11058 {
11063 }
11064 }
11066 /* Optimize tan(x)*cos(x) as sin(x). */
11075 {
11081 }
11083 /* Optimize x*pow(x,c) as pow(x,c+1). */
11087 {
11093 {
11095 REAL_VALUE_TYPE c;
11096 tree arg;
11102 }
11103 }
11105 /* Optimize pow(x,c)*x as pow(x,c+1). */
11109 {
11115 {
11117 REAL_VALUE_TYPE c;
11118 tree arg;
11124 }
11125 }
11127 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
11130 {
11134 {
11137 }
11138 }
11139 }
11140 }
11144 bit_ior:
11152 /* ~X | X is -1. */
11155 {
11159 }
11161 /* X | ~X is -1. */
11164 {
11168 }
11170 /* Canonicalize (X & C1) | C2. */
11174 {
11182 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11188 {
11192 }
11193 else
11194 {
11198 }
11200 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11205 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11206 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11207 mode which allows further optimizations. */
11217 {
11218 unsigned HOST_WIDE_INT mask
11222 {
11226 }
11227 }
11234 arg1);
11235 }
11237 /* (X & Y) | Y is (X, Y). */
11241 /* (X & Y) | X is (Y, X). */
11246 /* X | (X & Y) is (Y, X). */
11251 /* X | (Y & X) is (Y, X). */
11261 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11263 This results in more efficient code for machines without a NAND
11264 instruction. Combine will canonicalize to the first form
11265 which will allow use of NAND instructions provided by the
11266 backend if they exist. */
11269 {
11270 return
11277 }
11279 /* See if this can be simplified into a rotate first. If that
11280 is unsuccessful continue in the association code. */
11291 /* ~X ^ X is -1. */
11294 {
11298 }
11300 /* X ^ ~X is -1. */
11303 {
11307 }
11309 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11310 with a constant, and the two constants have no bits in common,
11311 we should treat this as a BIT_IOR_EXPR since this may produce more
11312 simplifications. */
11320 {
11323 }
11325 /* (X | Y) ^ X -> Y & ~ X*/
11328 {
11331 arg1);
11336 }
11338 /* (Y | X) ^ X -> Y & ~ X*/
11341 {
11344 arg1);
11349 }
11351 /* X ^ (X | Y) -> Y & ~ X*/
11354 {
11357 arg0);
11362 }
11364 /* X ^ (Y | X) -> Y & ~ X*/
11367 {
11370 arg0);
11375 }
11377 /* Convert ~X ^ ~Y to X ^ Y. */
11386 /* Convert ~X ^ C to X ^ ~C. */
11394 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11401 /* Fold (X & Y) ^ Y as ~X & Y. */
11404 {
11409 }
11410 /* Fold (X & Y) ^ X as ~Y & X. */
11414 {
11419 }
11420 /* Fold X ^ (X & Y) as X & ~Y. */
11423 {
11428 }
11429 /* Fold X ^ (Y & X) as ~Y & X. */
11433 {
11438 }
11440 /* See if this can be simplified into a rotate first. If that
11441 is unsuccessful continue in the association code. */
11452 /* ~X & X is always zero. */
11457 /* X & ~X is always zero. */
11462 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11466 {
11472 return
11476 }
11478 /* (X | Y) & Y is (X, Y). */
11482 /* (X | Y) & X is (Y, X). */
11487 /* X & (X | Y) is (Y, X). */
11492 /* X & (Y | X) is (Y, X). */
11498 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11502 {
11508 }
11509 /* Fold ~X & 1 as (X & 1) == 0. */
11512 {
11518 }
11520 /* Fold (X ^ Y) & Y as ~X & Y. */
11523 {
11528 }
11529 /* Fold (X ^ Y) & X as ~Y & X. */
11533 {
11538 }
11539 /* Fold X & (X ^ Y) as X & ~Y. */
11542 {
11547 }
11548 /* Fold X & (Y ^ X) as ~Y & X. */
11552 {
11557 }
11562 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11565 {
11566 unsigned int prec
11572 return
11574 }
11576 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11578 This results in more efficient code for machines without a NOR
11579 instruction. Combine will canonicalize to the first form
11580 which will allow use of NOR instructions provided by the
11581 backend if they exist. */
11584 {
11591 }
11593 /* If arg0 is derived from the address of an object or function, we may
11594 be able to fold this expression using the object or function's
11595 alignment. */
11597 {
11604 /* This works because modulus is a power of 2. If this weren't the
11605 case, we'd have to replace it by its greatest power-of-2
11606 divisor: modulus & -modulus. */
11609 }
11611 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11612 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11613 if the new mask might be further optimized. */
11622 {
11624 unsigned HOST_WIDE_INT mask
11634 {
11637 /* See if more bits can be proven as zero because of
11638 zero extension. */
11641 {
11646 {
11648 /* See if we can shorten the right shift. */
11651 }
11652 }
11656 /* For arithmetic shift if sign bit could be set, zerobits
11657 can contain actually sign bits, so no transformation is
11658 possible, unless MASK masks them all away. In that
11659 case the shift needs to be converted into logical shift. */
11662 {
11665 else
11667 }
11668 }
11670 /* ((X << 16) & 0xff00) is (X, 0). */
11677 {
11680 /* Only do the transformation if NEWMASK is some integer
11681 mode's mask. */
11688 {
11689 tree newmaskt;
11692 {
11698 }
11699 else
11704 }
11705 }
11706 }
11711 /* Don't touch a floating-point divide by zero unless the mode
11712 of the constant can represent infinity. */
11718 /* Optimize A / A to 1.0 if we don't care about
11719 NaNs or Infinities. Skip the transformation
11720 for non-real operands. */
11725 {
11729 }
11731 /* The complex version of the above A / A optimization. */
11734 {
11738 {
11740 /* omit_two_operands will call fold_convert for us. */
11742 }
11743 }
11745 /* (-A) / (-B) -> A / B */
11755 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11760 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11766 /* If ARG1 is a constant, we can convert this to a multiply by the
11767 reciprocal. This does not have the same rounding properties,
11768 so only do this if -freciprocal-math. We can actually
11769 always safely do it if ARG1 is a power of two, but it's hard to
11770 tell if it is or not in a portable manner. */
11772 {
11777 /* Find the reciprocal if optimizing and the result is exact. */
11779 {
11780 REAL_VALUE_TYPE r;
11783 {
11787 }
11788 }
11789 }
11790 /* Convert A/B/C to A/(B*C). */
11797 /* Convert A/(B/C) to (A/B)*C. */
11805 /* Convert C1/(X*C2) into (C1/C2)/X. */
11810 {
11816 }
11819 {
11823 /* Optimize sin(x)/cos(x) as tan(x). */
11829 {
11834 }
11836 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11842 {
11846 {
11851 }
11852 }
11854 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11855 NaNs or Infinities. */
11859 {
11866 {
11871 }
11872 }
11874 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11875 NaNs or Infinities. */
11879 {
11886 {
11890 {
11894 tmp);
11895 }
11896 }
11897 }
11899 /* Optimize pow(x,c)/x as pow(x,c-1). */
11903 {
11909 {
11911 REAL_VALUE_TYPE c;
11912 tree arg;
11918 }
11919 }
11921 /* Optimize a/root(b/c) into a*root(c/b). */
11923 {
11927 {
11936 }
11937 }
11939 /* Optimize x/expN(y) into x*expN(-y). */
11941 {
11948 }
11950 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11954 {
11962 }
11963 }
11968 /* Simplify A / (B << N) where A and B are positive and B is
11969 a power of 2, to A >> (N + log2(B)). */
11974 {
11977 {
11984 WARN_STRICT_OVERFLOW_MISC);
11990 }
11991 }
11993 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11994 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12000 /* Fall thru */
12009 /* X / -1 is -X. */
12016 /* Convert -A / -B to A / B when the type is signed and overflow is
12017 undefined. */
12021 {
12024 "when distributing negation across "
12026 WARN_STRICT_OVERFLOW_MISC);
12032 }
12036 {
12039 "when distributing negation across "
12041 WARN_STRICT_OVERFLOW_MISC);
12047 }
12049 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12050 operation, EXACT_DIV_EXPR.
12052 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12053 At one time others generated faster code, it's not clear if they do
12054 after the last round to changes to the DIV code in expmed.c. */
12063 {
12067 WARN_STRICT_OVERFLOW_MISC);
12069 }
12077 /* X % 1 is always zero, but be sure to preserve any side
12078 effects in X. */
12082 /* X % 0, return X % 0 unchanged so that we can get the
12083 proper warnings and errors. */
12087 /* 0 % X is always zero, but be sure to preserve any side
12088 effects in X. Place this after checking for X == 0. */
12092 /* X % -1 is zero. */
12099 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12100 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12105 {
12107 /* Also optimize A % (C << N) where C is a power of 2,
12108 to A & ((C << N) - 1). */
12113 {
12118 "occur when simplifying "
12120 WARN_STRICT_OVERFLOW_MISC);
12124 }
12125 }
12127 /* X % -C is the same as X % C. */
12134 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12141 /* X % -Y is the same as X % Y. */
12153 {
12157 WARN_STRICT_OVERFLOW_MISC);
12159 }
12170 /* Optimize -1 >> x for arithmetic right shifts. */
12174 /* ... fall through ... */
12177 shift:
12183 /* Since negative shift count is not well-defined,
12184 don't try to compute it in the compiler. */
12188 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12193 {
12197 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12198 being well defined. */
12200 {
12206 else
12208 }
12212 }
12214 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12215 into x & ((unsigned)-1 >> c) for unsigned types. */
12223 {
12226 tree lshift;
12227 tree arg00;
12230 {
12237 }
12238 }
12240 /* Rewrite an LROTATE_EXPR by a constant into an
12241 RROTATE_EXPR by a new constant. */
12243 {
12248 }
12250 /* If we have a rotate of a bit operation with the rotate count and
12251 the second operand of the bit operation both constant,
12252 permute the two operations. */
12264 /* Two consecutive rotates adding up to the precision of the
12265 type can be ignored. */
12276 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12277 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12278 if the latter can be further optimized. */
12283 {
12287 arg1);
12291 arg1);
12295 }
12323 /* Note that the operands of this must be ints
12324 and their values must be 0 or 1.
12325 ("true" is a fixed value perhaps depending on the language.) */
12326 /* If first arg is constant zero, return it. */
12330 /* If either arg is constant true, drop it. */
12334 /* Preserve sequence points. */
12337 /* If second arg is constant zero, result is zero, but first arg
12338 must be evaluated. */
12341 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12342 case will be handled here. */
12346 /* !X && X is always false. */
12350 /* X && !X is always false. */
12355 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12356 means A >= Y && A != MAX, but in this case we know that
12357 A < X <= MAX. */
12361 {
12369 }
12371 truth_andor:
12372 /* We only do these simplifications if we are optimizing. */
12376 /* Check for things like (A || B) && (A || C). We can convert this
12377 to A || (B && C). Note that either operator can be any of the four
12378 truth and/or operations and the transformation will still be
12379 valid. Also note that we only care about order for the
12380 ANDIF and ORIF operators. If B contains side effects, this
12381 might change the truth-value of A. */
12388 {
12408 /* This case if tricky because we must either have commutative
12409 operators or else A10 must not have side-effects. */
12415 a01);
12416 }
12418 /* See if we can build a range comparison. */
12422 /* Check for the possibility of merging component references. If our
12423 lhs is another similar operation, try to merge its rhs with our
12424 rhs. Then try to merge our lhs and rhs. */
12436 /* Note that the operands of this must be ints
12437 and their values must be 0 or true.
12438 ("true" is a fixed value perhaps depending on the language.) */
12439 /* If first arg is constant true, return it. */
12443 /* If either arg is constant zero, drop it. */
12447 /* Preserve sequence points. */
12450 /* If second arg is constant true, result is true, but we must
12451 evaluate first arg. */
12454 /* Likewise for first arg, but note this only occurs here for
12455 TRUTH_OR_EXPR. */
12459 /* !X || X is always true. */
12463 /* X || !X is always true. */
12471 /* If the second arg is constant zero, drop it. */
12474 /* If the second arg is constant true, this is a logical inversion. */
12476 {
12477 /* Only call invert_truthvalue if operand is a truth value. */
12480 else
12483 }
12484 /* Identical arguments cancel to zero. */
12488 /* !X ^ X is always true. */
12493 /* X ^ !X is always true. */
12506 /* bool_var != 0 becomes bool_var. */
12511 /* bool_var == 1 becomes bool_var. */
12516 /* bool_var != 1 becomes !bool_var. */
12522 /* bool_var == 0 becomes !bool_var. */
12528 /* If this is an equality comparison of the address of two non-weak,
12529 unaliased symbols neither of which are extern (since we do not
12530 have access to attributes for externs), then we know the result. */
12543 {
12544 /* We know that we're looking at the address of two
12545 non-weak, unaliased, static _DECL nodes.
12547 It is both wasteful and incorrect to call operand_equal_p
12548 to compare the two ADDR_EXPR nodes. It is wasteful in that
12549 all we need to do is test pointer equality for the arguments
12550 to the two ADDR_EXPR nodes. It is incorrect to use
12551 operand_equal_p as that function is NOT equivalent to a
12552 C equality test. It can in fact return false for two
12553 objects which would test as equal using the C equality
12554 operator. */
12558 type);
12559 }
12561 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12562 a MINUS_EXPR of a constant, we can convert it into a comparison with
12563 a revised constant as long as no overflow occurs. */
12571 arg1),
12576 /* Similarly for a NEGATE_EXPR. */
12584 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12592 arg1),
12595 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12602 {
12606 val,
12610 }
12612 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12617 {
12619 code == NE_EXPR
12622 }
12624 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12625 for !=. Don't do this for ordered comparisons due to overflow. */
12631 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12636 /* If this is an EQ or NE comparison with zero and ARG0 is
12637 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12638 two operations, but the latter can be done in one less insn
12639 on machines that have only two-operand insns or on which a
12640 constant cannot be the first operand. */
12643 {
12648 {
12655 arg1);
12656 }
12659 {
12666 arg1);
12667 }
12668 }
12670 /* If this is an NE or EQ comparison of zero against the result of a
12671 signed MOD operation whose second operand is a power of 2, make
12672 the MOD operation unsigned since it is simpler and equivalent. */
12680 {
12690 }
12692 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12693 C1 is a valid shift constant, and C2 is a power of two, i.e.
12694 a single bit. */
12698 == INTEGER_CST
12701 {
12706 /* Check for a valid shift count. */
12709 {
12713 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12714 can be rewritten as (X & (C2 << C1)) != 0. */
12716 {
12720 }
12721 /* Otherwise, for signed (arithmetic) shifts,
12722 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12723 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12727 /* Otherwise, of unsigned (logical) shifts,
12728 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12729 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12730 else
12734 arg000);
12735 }
12736 }
12738 /* If this is an NE comparison of zero with an AND of one, remove the
12739 comparison since the AND will give the correct value. */
12746 /* If we have (A & C) == C where C is a power of 2, convert this into
12747 (A & C) != 0. Similarly for NE_EXPR. */
12753 integer_zero_node));
12755 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12756 bit, then fold the expression into A < 0 or A >= 0. */
12761 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12762 Similarly for NE_EXPR. */
12766 {
12775 }
12777 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12778 Similarly for NE_EXPR. */
12782 {
12789 }
12791 /* If this is a comparison of a field, we may be able to simplify it. */
12794 /* Handle the constant case even without -O
12795 to make sure the warnings are given. */
12797 {
12801 }
12803 /* Optimize comparisons of strlen vs zero to a compare of the
12804 first character of the string vs zero. To wit,
12805 strlen(ptr) == 0 => *ptr == 0
12806 strlen(ptr) != 0 => *ptr != 0
12807 Other cases should reduce to one of these two (or a constant)
12808 due to the return value of strlen being unsigned. */
12811 {
12819 {
12824 }
12825 }
12827 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12828 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12832 {
12839 {
12841 {
12844 }
12847 }
12848 }
12850 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12856 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12861 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12868 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12876 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12877 (X & C) == 0 when C is a single bit. */
12882 {
12888 }
12890 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12891 constant C is a power of two, i.e. a single bit. */
12898 {
12902 }
12904 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12905 when is C is a power of two, i.e. a single bit. */
12912 {
12918 }
12922 {
12925 }
12927 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12934 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12937 {
12950 arg01),
12959 arg01),
12968 arg00),
12977 arg00),
12979 }
12983 {
12990 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12991 operand_equal_p guarantees no side-effects so we don't need
12992 to use omit_one_operand on Z. */
13002 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13010 arg10);
13011 }
13013 /* Attempt to simplify equality/inequality comparisons of complex
13014 values. Only lower the comparison if the result is known or
13015 can be simplified to a single scalar comparison. */
13020 {
13025 {
13028 }
13029 else
13030 {
13033 }
13036 {
13039 }
13040 else
13041 {
13044 }
13048 {
13050 {
13055 }
13056 else
13057 {
13062 }
13063 }
13067 {
13069 {
13074 }
13075 else
13076 {
13081 }
13082 }
13083 }
13095 /* Transform comparisons of the form X +- C CMP X. */
13102 {
13109 else
13112 /* (X - c) > X becomes false. */
13116 {
13120 "occur when assuming that (X - c) > X "
13122 WARN_STRICT_OVERFLOW_ALL);
13124 }
13126 /* Likewise (X + c) < X becomes false. */
13130 {
13134 "occur when assuming that "
13136 WARN_STRICT_OVERFLOW_ALL);
13138 }
13140 /* Convert (X - c) <= X to true. */
13145 {
13149 "occur when assuming that "
13151 WARN_STRICT_OVERFLOW_ALL);
13153 }
13155 /* Convert (X + c) >= X to true. */
13160 {
13164 "occur when assuming that "
13166 WARN_STRICT_OVERFLOW_ALL);
13168 }
13171 {
13172 /* Convert X + c > X and X - c < X to true for integers. */
13176 {
13179 "not occur when assuming that "
13181 WARN_STRICT_OVERFLOW_ALL);
13183 }
13188 {
13191 "not occur when assuming that "
13193 WARN_STRICT_OVERFLOW_ALL);
13195 }
13197 /* Convert X + c <= X and X - c >= X to false for integers. */
13201 {
13204 "not occur when assuming that "
13206 WARN_STRICT_OVERFLOW_ALL);
13208 }
13213 {
13216 "not occur when assuming that "
13218 WARN_STRICT_OVERFLOW_ALL);
13220 }
13221 }
13222 }
13224 /* Comparisons with the highest or lowest possible integer of
13225 the specified precision will have known values. */
13226 {
13233 {
13234 HOST_WIDE_INT signed_max_hi;
13239 {
13246 {
13250 }
13251 else
13252 {
13256 }
13257 }
13258 else
13259 {
13268 {
13271 }
13272 else
13273 {
13276 }
13277 }
13282 {
13295 /* The GE_EXPR and LT_EXPR cases above are not normally
13296 reached because of previous transformations. */
13300 }
13302 == max_hi
13305 {
13312 arg1);
13318 arg0),
13319 arg1);
13322 }
13324 == min_hi
13327 {
13342 }
13344 == min_hi
13347 {
13353 arg1);
13358 arg0),
13359 arg1);
13362 }
13367 /* We will flip the signedness of the comparison operator
13368 associated with the mode of arg1, so the sign bit is
13369 specified by this mode. Check that arg1 is the signed
13370 max associated with this sign bit. */
13372 /* signed_type does not work on pointer types. */
13374 {
13375 /* The following case also applies to X < signed_max+1
13376 and X >= signed_max+1 because previous transformations. */
13378 {
13379 tree st;
13385 }
13386 }
13387 }
13388 }
13390 /* If we are comparing an ABS_EXPR with a constant, we can
13391 convert all the cases into explicit comparisons, but they may
13392 well not be faster than doing the ABS and one comparison.
13393 But ABS (X) <= C is a range comparison, which becomes a subtraction
13394 and a comparison, and is probably faster. */
13408 /* Convert ABS_EXPR<x> >= 0 to true. */
13415 {
13418 "when simplifying comparison of "
13420 WARN_STRICT_OVERFLOW_CONDITIONAL);
13422 }
13424 /* Convert ABS_EXPR<x> < 0 to false. */
13429 {
13432 "when simplifying comparison of "
13434 WARN_STRICT_OVERFLOW_CONDITIONAL);
13436 }
13438 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13439 and similarly for >= into !=. */
13444 {
13450 }
13457 {
13466 }
13479 {
13483 }
13485 /* If the first operand is NaN, the result is constant. */
13489 {
13491 ? integer_zero_node
13494 }
13496 /* If the second operand is NaN, the result is constant. */
13500 {
13502 ? integer_zero_node
13505 }
13507 /* Simplify unordered comparison of something with itself. */
13513 && !flag_trapping_math
13517 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13518 {
13530 }
13535 /* When pedantic, a compound expression can be neither an lvalue
13536 nor an integer constant expression. */
13539 /* Don't let (0, 0) be null pointer constant. */
13553 /* An ASSERT_EXPR should never be passed to fold_binary. */
13559 fold_binary_exit:
13562 }
13564 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13565 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13566 of GOTO_EXPR. */
13568 static tree
13570 {
13572 {
13579 /* ... fall through ... */
13583 }
13584 }
13586 /* Return whether the sub-tree ST contains a label which is accessible from
13587 outside the sub-tree. */
13589 static bool
13591 {
13592 return
13594 }
13596 /* Fold a ternary expression of code CODE and type TYPE with operands
13597 OP0, OP1, and OP2. Return the folded expression if folding is
13598 successful. Otherwise, return NULL_TREE. */
13600 tree
13603 {
13604 tree tem;
13611 /* Strip any conversions that don't change the mode. This is safe
13612 for every expression, except for a comparison expression because
13613 its signedness is derived from its operands. So, in the latter
13614 case, only strip conversions that don't change the signedness.
13616 Note that this is done as an internal manipulation within the
13617 constant folder, in order to find the simplest representation of
13618 the arguments so that their form can be studied. In any cases,
13619 the appropriate type conversions should be put back in the tree
13620 that will get out of the constant folder. */
13622 {
13625 }
13628 {
13631 }
13634 {
13638 {
13644 }
13648 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13649 so all simple results must be passed through pedantic_non_lvalue. */
13651 {
13654 /* Only optimize constant conditions when the selected branch
13655 has the same type as the COND_EXPR. This avoids optimizing
13656 away "c ? x : throw", where the throw has a void type.
13657 Avoid throwing away that operand which contains label. */
13664 }
13668 /* If we have A op B ? A : C, we may be able to convert this to a
13669 simpler expression, depending on the operation and the values
13670 of B and C. Signed zeros prevent all of these transformations,
13671 for reasons given above each one.
13673 Also try swapping the arguments and inverting the conditional. */
13678 {
13682 }
13686 op2,
13689 {
13692 {
13696 }
13697 }
13699 /* If the second operand is simpler than the third, swap them
13700 since that produces better jump optimization results. */
13703 {
13704 /* See if this can be inverted. If it can't, possibly because
13705 it was a floating-point inequality comparison, don't do
13706 anything. */
13710 }
13712 /* Convert A ? 1 : 0 to simply A. */
13715 /* If we try to convert OP0 to our type, the
13716 call to fold will try to move the conversion inside
13717 a COND, which will recurse. In that case, the COND_EXPR
13718 is probably the best choice, so leave it alone. */
13722 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13723 over COND_EXPR in cases such as floating point comparisons. */
13730 arg0)));
13732 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13737 {
13738 /* sign_bit_p only checks ARG1 bits within A's precision.
13739 If <sign bit of A> has wider type than A, bits outside
13740 of A's precision in <sign bit of A> need to be checked.
13741 If they are all 0, this optimization needs to be done
13742 in unsigned A's type, if they are all 1 in signed A's type,
13743 otherwise this can't be done. */
13748 {
13750 HOST_WIDE_INT mask_hi;
13752 tree tem_type;
13760 {
13764 }
13765 else
13766 {
13770 }
13772 {
13776 }
13777 else
13783 {
13786 }
13789 {
13792 }
13793 else
13795 }
13798 return
13804 arg1)));
13805 }
13807 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13808 already handled above. */
13813 {
13822 }
13824 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13825 is probably obsolete because the first operand should be a
13826 truth value (that's why we have the two cases above), but let's
13827 leave it in until we can confirm this for all front-ends. */
13839 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13845 arg1);
13847 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13851 {
13852 /* Only perform transformation if ARG0 is easily inverted. */
13857 arg1);
13858 }
13860 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13864 {
13865 /* Only perform transformation if ARG0 is easily inverted. */
13870 op2);
13871 }
13873 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13879 op2);
13884 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13885 of fold_ternary on them. */
13892 {
13901 {
13906 else
13907 {
13909 tree value;
13913 }
13918 else
13920 }
13921 }
13923 /* A bit-field-ref that referenced the full argument can be stripped. */
13934 }
13936 /* Perform constant folding and related simplification of EXPR.
13937 The related simplifications include x*1 => x, x*0 => 0, etc.,
13938 and application of the associative law.
13939 NOP_EXPR conversions may be removed freely (as long as we
13940 are careful not to change the type of the overall expression).
13941 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13942 but we can constant-fold them if they have constant operands. */
13944 #ifdef ENABLE_FOLD_CHECKING
13945 # define fold(x) fold_1 (x)
13947 static
13948 #endif
13949 tree
13951 {
13955 tree tem;
13958 /* Return right away if a constant. */
13962 /* CALL_EXPR-like objects with variable numbers of operands are
13963 treated specially. */
13965 {
13967 {
13970 }
13972 }
13975 {
13980 {
13998 }
13999 }
14002 {
14004 {
14011 {
14016 /* Find a matching index by means of a binary search. */
14018 {
14034 else
14036 }
14037 }
14040 }
14048 }
14050 #ifdef ENABLE_FOLD_CHECKING
14051 #undef fold
14057 /* When --enable-checking=fold, compute a digest of expr before
14058 and after actual fold call to see if fold did not accidentally
14059 change original expr. */
14061 tree
14063 {
14064 tree ret;
14067 htab_t ht;
14086 }
14088 void
14090 {
14093 htab_t ht;
14103 }
14105 static void
14107 {
14109 }
14111 static void
14113 {
14119 recursive_label:
14133 {
14134 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14138 }
14145 {
14146 /* Allow these fields to be modified. */
14147 tree tmp;
14155 {
14158 }
14159 }
14168 {
14171 {
14185 }
14189 {
14202 }
14219 {
14225 }
14230 {
14234 }
14245 {
14248 }
14258 }
14259 }
14261 /* Helper function for outputting the checksum of a tree T. When
14262 debugging with gdb, you can "define mynext" to be "next" followed
14263 by "call debug_fold_checksum (op0)", then just trace down till the
14264 outputs differ. */
14266 void
14268 {
14283 }
14285 #endif
14287 /* Fold a unary tree expression with code CODE of type TYPE with an
14288 operand OP0. LOC is the location of the resulting expression.
14289 Return a folded expression if successful. Otherwise, return a tree
14290 expression with code CODE of type TYPE with an operand OP0. */
14292 tree
14295 {
14296 tree tem;
14297 #ifdef ENABLE_FOLD_CHECKING
14300 htab_t ht;
14307 #endif
14311 {
14314 }
14316 #ifdef ENABLE_FOLD_CHECKING
14324 #endif
14326 }
14328 /* Fold a binary tree expression with code CODE of type TYPE with
14329 operands OP0 and OP1. LOC is the location of the resulting
14330 expression. Return a folded expression if successful. Otherwise,
14331 return a tree expression with code CODE of type TYPE with operands
14332 OP0 and OP1. */
14334 tree
14337 MEM_STAT_DECL)
14338 {
14339 tree tem;
14340 #ifdef ENABLE_FOLD_CHECKING
14346 htab_t ht;
14358 #endif
14362 {
14365 }
14367 #ifdef ENABLE_FOLD_CHECKING
14383 #endif
14385 }
14387 /* Fold a ternary tree expression with code CODE of type TYPE with
14388 operands OP0, OP1, and OP2. Return a folded expression if
14389 successful. Otherwise, return a tree expression with code CODE of
14390 type TYPE with operands OP0, OP1, and OP2. */
14392 tree
14395 {
14396 tree tem;
14397 #ifdef ENABLE_FOLD_CHECKING
14405 htab_t ht;
14422 #endif
14427 {
14430 }
14432 #ifdef ENABLE_FOLD_CHECKING
14456 #endif
14458 }
14460 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14461 arguments in ARGARRAY, and a null static chain.
14462 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14463 of type TYPE from the given operands as constructed by build_call_array. */
14465 tree
14468 {
14469 tree tem;
14470 #ifdef ENABLE_FOLD_CHECKING
14476 htab_t ht;
14490 #endif
14494 #ifdef ENABLE_FOLD_CHECKING
14511 #endif
14513 }
14515 /* Perform constant folding and related simplification of initializer
14516 expression EXPR. These behave identically to "fold_buildN" but ignore
14517 potential run-time traps and exceptions that fold must preserve. */
14519 #define START_FOLD_INIT \
14520 int saved_signaling_nans = flag_signaling_nans;\
14521 int saved_trapping_math = flag_trapping_math;\
14522 int saved_rounding_math = flag_rounding_math;\
14523 int saved_trapv = flag_trapv;\
14524 int saved_folding_initializer = folding_initializer;\
14525 flag_signaling_nans = 0;\
14526 flag_trapping_math = 0;\
14527 flag_rounding_math = 0;\
14528 flag_trapv = 0;\
14529 folding_initializer = 1;
14531 #define END_FOLD_INIT \
14532 flag_signaling_nans = saved_signaling_nans;\
14533 flag_trapping_math = saved_trapping_math;\
14534 flag_rounding_math = saved_rounding_math;\
14535 flag_trapv = saved_trapv;\
14536 folding_initializer = saved_folding_initializer;
14538 tree
14541 {
14542 tree result;
14543 START_FOLD_INIT;
14547 END_FOLD_INIT;
14549 }
14551 tree
14554 {
14555 tree result;
14556 START_FOLD_INIT;
14560 END_FOLD_INIT;
14562 }
14564 tree
14567 {
14568 tree result;
14569 START_FOLD_INIT;
14573 END_FOLD_INIT;
14575 }
14577 tree
14580 {
14581 tree result;
14582 START_FOLD_INIT;
14586 END_FOLD_INIT;
14588 }
14590 #undef START_FOLD_INIT
14591 #undef END_FOLD_INIT
14593 /* Determine if first argument is a multiple of second argument. Return 0 if
14594 it is not, or we cannot easily determined it to be.
14596 An example of the sort of thing we care about (at this point; this routine
14597 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14598 fold cases do now) is discovering that
14600 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14602 is a multiple of
14604 SAVE_EXPR (J * 8)
14606 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14608 This code also handles discovering that
14610 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14612 is a multiple of 8 so we don't have to worry about dealing with a
14613 possible remainder.
14615 Note that we *look* inside a SAVE_EXPR only to determine how it was
14616 calculated; it is not safe for fold to do much of anything else with the
14617 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14618 at run time. For example, the latter example above *cannot* be implemented
14619 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14620 evaluation time of the original SAVE_EXPR is not necessarily the same at
14621 the time the new expression is evaluated. The only optimization of this
14622 sort that would be valid is changing
14624 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14626 divided by 8 to
14628 SAVE_EXPR (I) * SAVE_EXPR (J)
14630 (where the same SAVE_EXPR (J) is used in the original and the
14631 transformed version). */
14633 int
14635 {
14643 {
14645 /* Bitwise and provides a power of two multiple. If the mask is
14646 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14649 /* FALLTHRU */
14662 {
14666 /* const_binop may not detect overflow correctly,
14667 so check for it explicitly here. */
14673 size_one_node,
14677 }
14681 /* Can't handle conversions from non-integral or wider integral type. */
14687 /* .. fall through ... */
14704 }
14705 }
14707 /* Return true if CODE or TYPE is known to be non-negative. */
14709 static bool
14711 {
14714 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14715 have a signed:1 type (where the value is -1 and 0). */
14718 }
14720 /* Return true if (CODE OP0) is known to be non-negative. If the return
14721 value is based on the assumption that signed overflow is undefined,
14722 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14723 *STRICT_OVERFLOW_P. */
14725 bool
14728 {
14733 {
14735 /* We can't return 1 if flag_wrapv is set because
14736 ABS_EXPR<INT_MIN> = INT_MIN. */
14740 {
14743 }
14750 strict_overflow_p);
14753 {
14758 {
14761 strict_overflow_p);
14763 {
14767 strict_overflow_p);
14768 }
14769 }
14771 {
14774 strict_overflow_p);
14778 }
14779 }
14784 }
14786 /* We don't know sign of `t', so be conservative and return false. */
14788 }
14790 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14791 value is based on the assumption that signed overflow is undefined,
14792 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14793 *STRICT_OVERFLOW_P. */
14795 bool
14798 {
14803 {
14808 strict_overflow_p)
14810 strict_overflow_p));
14812 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14813 both unsigned and at least 2 bits shorter than the result. */
14817 {
14822 {
14826 }
14827 }
14832 {
14833 /* x * x for floating point x is always non-negative. */
14837 strict_overflow_p)
14839 strict_overflow_p));
14840 }
14842 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14843 both unsigned and their total bits is shorter than the result. */
14847 {
14866 {
14876 }
14877 }
14883 strict_overflow_p)
14885 strict_overflow_p));
14896 strict_overflow_p)
14898 strict_overflow_p));
14905 strict_overflow_p);
14908 }
14910 /* We don't know sign of `t', so be conservative and return false. */
14912 }
14914 /* Return true if T is known to be non-negative. If the return
14915 value is based on the assumption that signed overflow is undefined,
14916 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14917 *STRICT_OVERFLOW_P. */
14919 bool
14921 {
14926 {
14938 strict_overflow_p)
14940 strict_overflow_p));
14944 }
14945 /* We don't know sign of `t', so be conservative and return false. */
14947 }
14949 /* Return true if T is known to be non-negative. If the return
14950 value is based on the assumption that signed overflow is undefined,
14951 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14952 *STRICT_OVERFLOW_P. */
14954 bool
14957 {
14960 {
14978 /* Always true. */
14982 /* sqrt(-0.0) is -0.0. */
14986 strict_overflow_p);
15019 /* True if the 1st argument is nonnegative. */
15021 strict_overflow_p);
15024 /* True if the 1st OR 2nd arguments are nonnegative. */
15026 strict_overflow_p)
15028 strict_overflow_p)));
15031 /* True if the 1st AND 2nd arguments are nonnegative. */
15033 strict_overflow_p)
15035 strict_overflow_p)));
15038 /* True if the 2nd argument is nonnegative. */
15040 strict_overflow_p);
15043 /* True if the 1st argument is nonnegative or the second
15044 argument is an even integer. */
15049 strict_overflow_p);
15052 /* True if the 1st argument is nonnegative or the second
15053 argument is an even integer valued real. */
15055 {
15056 REAL_VALUE_TYPE c;
15057 HOST_WIDE_INT n;
15062 {
15063 REAL_VALUE_TYPE cint;
15068 }
15069 }
15071 strict_overflow_p);
15075 }
15077 type);
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
15087 {
15093 {
15095 {
15099 /* If the initializer is non-void, then it's a normal expression
15100 that will be assigned to the slot. */
15104 /* Otherwise, the initializer sets the slot in some way. One common
15105 way is an assignment statement at the end of the initializer. */
15107 {
15115 else
15117 }
15121 strict_overflow_p);
15124 }
15127 {
15133 arg0,
15134 arg1,
15135 strict_overflow_p);
15136 }
15140 strict_overflow_p);
15143 strict_overflow_p);
15146 strict_overflow_p);
15151 }
15153 /* We don't know sign of `t', so be conservative and return false. */
15155 }
15157 /* Return true if T is known to be non-negative. If the return
15158 value is based on the assumption that signed overflow is undefined,
15159 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15160 *STRICT_OVERFLOW_P. */
15162 bool
15164 {
15171 {
15178 strict_overflow_p);
15184 strict_overflow_p);
15193 }
15196 {
15204 strict_overflow_p);
15209 strict_overflow_p);
15224 }
15225 }
15227 /* Return true if `t' is known to be non-negative. Handle warnings
15228 about undefined signed overflow. */
15230 bool
15232 {
15239 "determining that expression is always "
15241 WARN_STRICT_OVERFLOW_MISC);
15243 }
15246 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15247 For floating point we further ensure that T is not denormal.
15248 Similar logic is present in nonzero_address in rtlanal.h.
15250 If the return value is based on the assumption that signed overflow
15251 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15252 change *STRICT_OVERFLOW_P. */
15254 bool
15257 {
15259 {
15262 strict_overflow_p);
15265 {
15271 strict_overflow_p));
15272 }
15277 strict_overflow_p);
15281 }
15284 }
15286 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15287 For floating point we further ensure that T is not denormal.
15288 Similar logic is present in nonzero_address in rtlanal.h.
15290 If the return value is based on the assumption that signed overflow
15291 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15292 change *STRICT_OVERFLOW_P. */
15294 bool
15296 tree type,
15297 tree op0,
15299 {
15302 {
15306 {
15307 /* With the presence of negative values it is hard
15308 to say something. */
15315 /* One of operands must be positive and the other non-negative. */
15316 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15317 overflows, on a twos-complement machine the sum of two
15318 nonnegative numbers can never be zero. */
15320 strict_overflow_p)
15322 strict_overflow_p));
15323 }
15328 {
15330 strict_overflow_p)
15332 strict_overflow_p))
15333 {
15336 }
15337 }
15346 {
15349 }
15356 {
15360 /* When both operands are nonzero, then MAX must be too. */
15362 strict_overflow_p))
15365 /* MAX where operand 0 is positive is positive. */
15367 strict_overflow_p);
15368 }
15369 /* MAX where operand 1 is positive is positive. */
15374 {
15378 }
15383 strict_overflow_p)
15385 strict_overflow_p));
15389 }
15392 }
15394 /* Return true when T is an address and is known to be nonzero.
15395 For floating point we further ensure that T is not denormal.
15396 Similar logic is present in nonzero_address in rtlanal.h.
15398 If the return value is based on the assumption that signed overflow
15399 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15400 change *STRICT_OVERFLOW_P. */
15402 bool
15404 {
15407 {
15412 {
15418 /* Weak declarations may link to NULL. Other things may also be NULL
15419 so protect with -fdelete-null-pointer-checks; but not variables
15420 allocated on the stack. */
15422 && (flag_delete_null_pointer_checks
15426 /* Constants are never weak. */
15431 }
15439 {
15443 }
15448 }
15450 }
15452 /* Return true when T is an address and is known to be nonzero.
15453 For floating point we further ensure that T is not denormal.
15454 Similar logic is present in nonzero_address in rtlanal.h.
15456 If the return value is based on the assumption that signed overflow
15457 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15458 change *STRICT_OVERFLOW_P. */
15460 bool
15462 {
15466 /* Doing something useful for floating point would need more work. */
15472 {
15475 strict_overflow_p);
15481 strict_overflow_p);
15489 }
15492 {
15495 strict_overflow_p);
15503 strict_overflow_p);
15520 strict_overflow_p);
15524 strict_overflow_p);
15531 }
15533 }
15535 /* Return true when T is an address and is known to be nonzero.
15536 Handle warnings about undefined signed overflow. */
15538 bool
15540 {
15547 "determining that expression is always "
15549 WARN_STRICT_OVERFLOW_MISC);
15551 }
15553 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15554 attempt to fold the expression to a constant without modifying TYPE,
15555 OP0 or OP1.
15557 If the expression could be simplified to a constant, then return
15558 the constant. If the expression would not be simplified to a
15559 constant, then return NULL_TREE. */
15561 tree
15563 {
15566 }
15568 /* Given the components of a unary expression CODE, TYPE and OP0,
15569 attempt to fold the expression to a constant without modifying
15570 TYPE or OP0.
15572 If the expression could be simplified to a constant, then return
15573 the constant. If the expression would not be simplified to a
15574 constant, then return NULL_TREE. */
15576 tree
15578 {
15581 }
15583 /* If EXP represents referencing an element in a constant string
15584 (either via pointer arithmetic or array indexing), return the
15585 tree representing the value accessed, otherwise return NULL. */
15587 tree
15589 {
15593 {
15595 tree index;
15596 tree string;
15601 else
15602 {
15606 /* Optimize the special-case of a zero lower bound.
15608 We convert the low_bound to sizetype to avoid some problems
15609 with constant folding. (E.g. suppose the lower bound is 1,
15610 and its mode is QI. Without the conversion,l (ARRAY
15611 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15612 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15618 }
15631 }
15633 }
15635 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15636 an integer constant, real, or fixed-point constant.
15638 TYPE is the type of the result. */
15640 static tree
15642 {
15646 {
15648 {
15650 HOST_WIDE_INT high;
15658 }
15665 {
15666 FIXED_VALUE_TYPE f;
15671 /* Propagate overflow flags. */
15675 }
15679 }
15682 }
15684 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15685 an integer constant or real constant.
15687 TYPE is the type of the result. */
15689 tree
15691 {
15695 {
15697 /* If the value is unsigned, then the absolute value is
15698 the same as the ordinary value. */
15701 /* Similarly, if the value is non-negative. */
15704 /* If the value is negative, then the absolute value is
15705 its negation. */
15706 else
15707 {
15709 HOST_WIDE_INT high;
15715 }
15721 else
15727 }
15730 }
15732 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15733 constant. TYPE is the type of the result. */
15735 static tree
15737 {
15747 }
15749 /* Given CODE, a relational operator, the target type, TYPE and two
15750 constant operands OP0 and OP1, return the result of the
15751 relational operation. If the result is not a compile time
15752 constant, then return NULL_TREE. */
15754 static tree
15756 {
15759 /* From here on, the only cases we handle are when the result is
15760 known to be a constant. */
15763 {
15767 /* Handle the cases where either operand is a NaN. */
15769 {
15771 {
15799 }
15802 }
15805 }
15808 {
15812 }
15814 /* Handle equality/inequality of complex constants. */
15816 {
15827 else
15829 }
15831 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15833 To compute GT, swap the arguments and do LT.
15834 To compute GE, do LT and invert the result.
15835 To compute LE, swap the arguments, do LT and invert the result.
15836 To compute NE, do EQ and invert the result.
15838 Therefore, the code below must handle only EQ and LT. */
15841 {
15846 }
15848 /* Note that it is safe to invert for real values here because we
15849 have already handled the one case that it matters. */
15853 {
15856 }
15858 /* Compute a result for LT or EQ if args permit;
15859 Otherwise return T. */
15861 {
15866 else
15868 }
15869 else
15875 }
15877 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15878 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15879 itself. */
15881 tree
15883 {
15884 /* If the expression does not have side effects then we don't have to wrap
15885 it with a cleanup point expression. */
15889 /* If the expression is a return, check to see if the expression inside the
15890 return has no side effects or the right hand side of the modify expression
15891 inside the return. If either don't have side effects set we don't need to
15892 wrap the expression in a cleanup point expression. Note we don't check the
15893 left hand side of the modify because it should always be a return decl. */
15895 {
15902 }
15905 }
15907 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15908 of an indirection through OP0, or NULL_TREE if no simplification is
15909 possible. */
15911 tree
15913 {
15915 tree subtype;
15923 {
15926 /* *&CONST_DECL -> to the value of the const decl. */
15929 /* *&p => p; make sure to handle *&"str"[cst] here. */
15931 {
15935 else
15937 }
15938 /* *(foo *)&fooarray => fooarray[0] */
15941 {
15949 }
15950 /* *(foo *)&complexfoo => __real__ complexfoo */
15954 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15957 {
15961 }
15962 }
15964 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15967 {
15970 tree op00type;
15977 {
15989 }
15990 }
15993 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15996 {
15999 tree op00type;
16006 {
16011 }
16012 }
16014 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16017 {
16018 tree type_domain;
16027 }
16030 }
16032 /* Builds an expression for an indirection through T, simplifying some
16033 cases. */
16035 tree
16037 {
16047 }
16049 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16051 tree
16053 {
16058 else
16060 }
16062 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16063 whose result is ignored. The type of the returned tree need not be
16064 the same as the original expression. */
16066 tree
16068 {
16074 {
16085 else
16091 {
16107 }
16112 }
16113 }
16115 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
16116 This can only be applied to objects of a sizetype. */
16118 tree
16120 {
16127 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16128 have to do anything. Only do this when we are not given a const,
16129 because in that case, this check is more expensive than just
16130 doing it. */
16132 {
16137 }
16139 /* If divisor is a power of two, simplify this to bit manipulation. */
16141 {
16143 {
16156 {
16157 high++;
16160 }
16164 }
16165 else
16166 {
16167 tree t;
16173 }
16174 }
16175 else
16176 {
16181 }
16184 }
16186 /* Likewise, but round down. */
16188 tree
16190 {
16197 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16198 have to do anything. Only do this when we are not given a const,
16199 because in that case, this check is more expensive than just
16200 doing it. */
16202 {
16207 }
16209 /* If divisor is a power of two, simplify this to bit manipulation. */
16211 {
16212 tree t;
16216 }
16217 else
16218 {
16223 }
16226 }
16228 /* Returns the pointer to the base of the object addressed by EXP and
16229 extracts the information about the offset of the access, storing it
16230 to PBITPOS and POFFSET. */
16232 static tree
16235 {
16236 tree core;
16239 HOST_WIDE_INT bitsize;
16243 {
16248 }
16249 else
16250 {
16254 }
16257 }
16259 /* Returns true if addresses of E1 and E2 differ by a constant, false
16260 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16262 bool
16264 {
16278 {
16288 }
16290 {
16291 /* If only one of the offsets is non-constant, the difference cannot
16292 be a constant. */
16294 }
16295 else
16300 }
16302 /* Simplify the floating point expression EXP when the sign of the
16303 result is not significant. Return NULL_TREE if no simplification
16304 is possible. */
16306 tree
16308 {
16313 {
16349 {
16352 {
16354 /* Strip copysign function call, return the 1st argument. */
16360 /* Strip sign ops from the argument of "odd" math functions. */
16362 {
16366 }
16368 }
16369 }
16374 }
16376 }