| blob | 342e3760bdf0f524fca78ab0671c6a94c02efdda |
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 {
1975 #ifdef HAVE_mpc
1978 #endif
1983 notrunc);
1987 notrunc);
1991 #ifdef HAVE_mpc
1994 #endif
1996 {
1997 tree magsquared
2001 notrunc);
2002 tree t1
2006 notrunc);
2007 tree t2
2011 notrunc);
2018 }
2023 }
2027 }
2030 {
2042 {
2045 /* The trailing elements can be empty and should be treated as 0 */
2048 else
2049 {
2052 }
2056 else
2057 {
2060 }
2064 /* It is possible that const_binop cannot handle the given
2065 code and return NULL_TREE */
2070 }
2072 }
2074 }
2076 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2077 indicates which particular sizetype to create. */
2079 tree
2081 {
2083 }
2084 \f
2085 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2086 is a tree code. The type of the result is taken from the operands.
2087 Both must be equivalent integer types, ala int_binop_types_match_p.
2088 If the operands are constant, so is the result. */
2090 tree
2092 {
2101 /* Handle the special case of two integer constants faster. */
2103 {
2104 /* And some specific cases even faster than that. */
2106 {
2111 }
2113 {
2116 }
2118 {
2121 }
2123 /* Handle general case of two integer constants. */
2125 }
2128 }
2130 /* Given two values, either both of sizetype or both of bitsizetype,
2131 compute the difference between the two values. Return the value
2132 in signed type corresponding to the type of the operands. */
2134 tree
2136 {
2138 tree ctype;
2143 /* If the type is already signed, just do the simple thing. */
2151 else
2154 /* If either operand is not a constant, do the conversions to the signed
2155 type and subtract. The hardware will do the right thing with any
2156 overflow in the subtraction. */
2162 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2163 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2164 overflow) and negate (which can't either). Special-case a result
2165 of zero while we're here. */
2171 else
2175 MINUS_EXPR,
2177 }
2178 \f
2179 /* A subroutine of fold_convert_const handling conversions of an
2180 INTEGER_CST to another integer type. */
2182 static tree
2184 {
2185 tree t;
2187 /* Given an integer constant, make new constant with new type,
2188 appropriately sign-extended or truncated. */
2191 /* Don't set the overflow when
2192 converting from a pointer, */
2194 /* or to a sizetype with same signedness
2195 and the precision is unchanged.
2196 ??? sizetype is always sign-extended,
2197 but its signedness depends on the
2198 frontend. Thus we see spurious overflows
2199 here if we do not check this. */
2214 }
2216 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2217 to an integer type. */
2219 static tree
2221 {
2223 tree t;
2225 /* The following code implements the floating point to integer
2226 conversion rules required by the Java Language Specification,
2227 that IEEE NaNs are mapped to zero and values that overflow
2228 the target precision saturate, i.e. values greater than
2229 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2230 are mapped to INT_MIN. These semantics are allowed by the
2231 C and C++ standards that simply state that the behavior of
2232 FP-to-integer conversion is unspecified upon overflow. */
2235 REAL_VALUE_TYPE r;
2239 {
2246 }
2248 /* If R is NaN, return zero and show we have an overflow. */
2250 {
2254 }
2256 /* See if R is less than the lower bound or greater than the
2257 upper bound. */
2260 {
2264 {
2268 }
2269 }
2272 {
2275 {
2278 {
2282 }
2283 }
2284 }
2292 }
2294 /* A subroutine of fold_convert_const handling conversions of a
2295 FIXED_CST to an integer type. */
2297 static tree
2299 {
2300 tree t;
2304 /* Right shift FIXED_CST to temp by fbit. */
2308 {
2313 /* Left shift temp to temp_trunc by fbit. */
2318 }
2319 else
2320 {
2325 }
2327 /* If FIXED_CST is negative, we need to round the value toward 0.
2328 By checking if the fractional bits are not zero to add 1 to temp. */
2331 {
2332 double_int one;
2336 }
2338 /* Given a fixed-point constant, make new constant with new type,
2339 appropriately sign-extended or truncated. */
2347 }
2349 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2350 to another floating point type. */
2352 static tree
2354 {
2355 REAL_VALUE_TYPE value;
2356 tree t;
2361 /* If converting an infinity or NAN to a representation that doesn't
2362 have one, set the overflow bit so that we can produce some kind of
2363 error message at the appropriate point if necessary. It's not the
2364 most user-friendly message, but it's better than nothing. */
2371 /* Regular overflow, conversion produced an infinity in a mode that
2372 can't represent them. */
2377 else
2380 }
2382 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2383 to a floating point type. */
2385 static tree
2387 {
2388 REAL_VALUE_TYPE value;
2389 tree t;
2396 }
2398 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2399 to another fixed-point type. */
2401 static tree
2403 {
2404 FIXED_VALUE_TYPE value;
2405 tree t;
2412 /* Propagate overflow flags. */
2416 }
2418 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2419 to a fixed-point type. */
2421 static tree
2423 {
2424 FIXED_VALUE_TYPE value;
2425 tree t;
2434 /* Propagate overflow flags. */
2438 }
2440 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2441 to a fixed-point type. */
2443 static tree
2445 {
2446 FIXED_VALUE_TYPE value;
2447 tree t;
2455 /* Propagate overflow flags. */
2459 }
2461 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2462 type TYPE. If no simplification can be done return NULL_TREE. */
2464 static tree
2466 {
2472 {
2479 }
2481 {
2488 }
2490 {
2497 }
2499 }
2501 /* Construct a vector of zero elements of vector type TYPE. */
2503 static tree
2505 {
2516 }
2518 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2520 bool
2522 {
2537 {
2556 }
2557 }
2559 /* Convert expression ARG to type TYPE. Used by the middle-end for
2560 simple conversions in preference to calling the front-end's convert. */
2562 tree
2564 {
2566 tree tem;
2580 {
2585 {
2589 }
2603 {
2607 }
2609 {
2613 }
2615 {
2619 }
2622 {
2640 }
2645 {
2649 }
2652 {
2666 }
2670 {
2679 integer_zero_node));
2681 {
2685 {
2691 }
2699 }
2703 }
2721 }
2722 fold_convert_exit:
2725 }
2726 \f
2727 /* Return false if expr can be assumed not to be an lvalue, true
2728 otherwise. */
2730 static bool
2732 {
2733 /* We only need to wrap lvalue tree codes. */
2735 {
2769 /* Assume the worst for front-end tree codes. */
2773 }
2776 }
2778 /* Return an expr equal to X but certainly not valid as an lvalue. */
2780 tree
2782 {
2783 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2784 us. */
2793 }
2795 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2796 Zero means allow extended lvalues. */
2800 /* When pedantic, return an expr equal to X but certainly not valid as a
2801 pedantic lvalue. Otherwise, return X. */
2803 static tree
2805 {
2810 }
2811 \f
2812 /* Given a tree comparison code, return the code that is the logical inverse
2813 of the given code. It is not safe to do this for floating-point
2814 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2815 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2817 enum tree_code
2819 {
2824 {
2855 }
2856 }
2858 /* Similar, but return the comparison that results if the operands are
2859 swapped. This is safe for floating-point. */
2861 enum tree_code
2863 {
2865 {
2891 }
2892 }
2895 /* Convert a comparison tree code from an enum tree_code representation
2896 into a compcode bit-based encoding. This function is the inverse of
2897 compcode_to_comparison. */
2899 static enum comparison_code
2901 {
2903 {
2934 }
2935 }
2937 /* Convert a compcode bit-based encoding of a comparison operator back
2938 to GCC's enum tree_code representation. This function is the
2939 inverse of comparison_to_compcode. */
2941 static enum tree_code
2943 {
2945 {
2976 }
2977 }
2979 /* Return a tree for the comparison which is the combination of
2980 doing the AND or OR (depending on CODE) of the two operations LCODE
2981 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2982 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2983 if this makes the transformation invalid. */
2985 tree
2990 {
2997 {
3008 }
3011 {
3012 /* Eliminate unordered comparisons, as well as LTGT and ORD
3013 which are not used unless the mode has NaNs. */
3019 }
3021 {
3022 /* Check that the original operation and the optimized ones will trap
3023 under the same condition. */
3034 /* In a short-circuited boolean expression the LHS might be
3035 such that the RHS, if evaluated, will never trap. For
3036 example, in ORD (x, y) && (x < y), we evaluate the RHS only
3037 if neither x nor y is NaN. (This is a mixed blessing: for
3038 example, the expression above will never trap, hence
3039 optimizing it to x < y would be invalid). */
3044 /* If the comparison was short-circuited, and only the RHS
3045 trapped, we may now generate a spurious trap. */
3050 /* If we changed the conditions that cause a trap, we lose. */
3053 }
3059 else
3060 {
3065 }
3066 }
3067 \f
3068 /* Return nonzero if two operands (typically of the same tree node)
3069 are necessarily equal. If either argument has side-effects this
3070 function returns zero. FLAGS modifies behavior as follows:
3072 If OEP_ONLY_CONST is set, only return nonzero for constants.
3073 This function tests whether the operands are indistinguishable;
3074 it does not test whether they are equal using C's == operation.
3075 The distinction is important for IEEE floating point, because
3076 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3077 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3079 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3080 even though it may hold multiple values during a function.
3081 This is because a GCC tree node guarantees that nothing else is
3082 executed between the evaluation of its "operands" (which may often
3083 be evaluated in arbitrary order). Hence if the operands themselves
3084 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3085 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3086 unset means assuming isochronic (or instantaneous) tree equivalence.
3087 Unless comparing arbitrary expression trees, such as from different
3088 statements, this flag can usually be left unset.
3090 If OEP_PURE_SAME is set, then pure functions with identical arguments
3091 are considered the same. It is used when the caller has other ways
3092 to ensure that global memory is unchanged in between. */
3094 int
3096 {
3097 /* If either is ERROR_MARK, they aren't equal. */
3101 /* Check equality of integer constants before bailing out due to
3102 precision differences. */
3106 /* If both types don't have the same signedness, then we can't consider
3107 them equal. We must check this before the STRIP_NOPS calls
3108 because they may change the signedness of the arguments. As pointers
3109 strictly don't have a signedness, require either two pointers or
3110 two non-pointers as well. */
3115 /* If both types don't have the same precision, then it is not safe
3116 to strip NOPs. */
3123 /* In case both args are comparisons but with different comparison
3124 code, try to swap the comparison operands of one arg to produce
3125 a match and compare that variant. */
3129 {
3137 }
3140 /* This is needed for conversions and for COMPONENT_REF.
3141 Might as well play it safe and always test this. */
3147 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3148 We don't care about side effects in that case because the SAVE_EXPR
3149 takes care of that for us. In all other cases, two expressions are
3150 equal if they have no side effects. If we have two identical
3151 expressions with side effects that should be treated the same due
3152 to the only side effects being identical SAVE_EXPR's, that will
3153 be detected in the recursive calls below. */
3159 /* Next handle constant cases, those for which we can return 1 even
3160 if ONLY_CONST is set. */
3163 {
3178 {
3179 /* If we do not distinguish between signed and unsigned zero,
3180 consider them equal. */
3183 }
3187 {
3193 {
3195 flags))
3199 }
3202 }
3206 flags)
3208 flags));
3221 }
3226 /* Define macros to test an operand from arg0 and arg1 for equality and a
3227 variant that allows null and views null as being different from any
3228 non-null value. In the latter case, if either is null, the both
3229 must be; otherwise, do the normal comparison. */
3230 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3231 TREE_OPERAND (arg1, N), flags)
3233 #define OP_SAME_WITH_NULL(N) \
3234 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3235 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3238 {
3240 /* Two conversions are equal only if signedness and modes match. */
3242 {
3243 CASE_CONVERT:
3251 }
3261 /* For commutative ops, allow the other order. */
3269 /* If either of the pointer (or reference) expressions we are
3270 dereferencing contain a side effect, these cannot be equal. */
3276 {
3286 /* Operands 2 and 3 may be null.
3287 Compare the array index by value if it is constant first as we
3288 may have different types but same value here. */
3297 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3298 may be NULL when we're called to compare MEM_EXPRs. */
3308 }
3312 {
3327 /* Otherwise take into account this is a commutative operation. */
3338 }
3342 {
3344 /* If the CALL_EXPRs call different functions, then they
3345 clearly can not be equal. */
3347 flags))
3350 {
3354 else
3358 }
3360 /* Now see if all the arguments are the same. */
3361 {
3372 /* If we get here and both argument lists are exhausted
3373 then the CALL_EXPRs are equal. */
3375 }
3378 }
3381 /* Consider __builtin_sqrt equal to sqrt. */
3389 }
3391 #undef OP_SAME
3392 #undef OP_SAME_WITH_NULL
3393 }
3394 \f
3395 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3396 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3398 When in doubt, return 0. */
3400 static int
3402 {
3414 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3415 and see if the inner values are the same. This removes any
3416 signedness comparison, which doesn't matter here. */
3423 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3424 actual comparison operand, ARG0.
3426 First throw away any conversions to wider types
3427 already present in the operands. */
3436 {
3439 /* Make sure shorter operand is extended the right way
3440 to match the longer operand. */
3446 }
3449 }
3450 \f
3451 /* See if ARG is an expression that is either a comparison or is performing
3452 arithmetic on comparisons. The comparisons must only be comparing
3453 two different values, which will be stored in *CVAL1 and *CVAL2; if
3454 they are nonzero it means that some operands have already been found.
3455 No variables may be used anywhere else in the expression except in the
3456 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3457 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3459 If this is true, return 1. Otherwise, return zero. */
3461 static int
3463 {
3467 /* We can handle some of the tcc_expression cases here. */
3477 {
3478 /* If we've already found a CVAL1 or CVAL2, this expression is
3479 two complex to handle. */
3485 }
3488 {
3511 /* First see if we can handle the first operand, then the second. For
3512 the second operand, we know *CVAL1 can't be zero. It must be that
3513 one side of the comparison is each of the values; test for the
3514 case where this isn't true by failing if the two operands
3515 are the same. */
3524 ;
3528 ;
3529 else
3533 ;
3537 ;
3538 else
3545 }
3546 }
3547 \f
3548 /* ARG is a tree that is known to contain just arithmetic operations and
3549 comparisons. Evaluate the operations in the tree substituting NEW0 for
3550 any occurrence of OLD0 as an operand of a comparison and likewise for
3551 NEW1 and OLD1. */
3553 static tree
3556 {
3561 /* We can handle some of the tcc_expression cases here. */
3569 {
3584 {
3603 }
3604 /* Fall through - ??? */
3607 {
3611 /* We need to check both for exact equality and tree equality. The
3612 former will be true if the operand has a side-effect. In that
3613 case, we know the operand occurred exactly once. */
3626 }
3630 }
3631 }
3632 \f
3633 /* Return a tree for the case when the result of an expression is RESULT
3634 converted to TYPE and OMITTED was previously an operand of the expression
3635 but is now not needed (e.g., we folded OMITTED * 0).
3637 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3638 the conversion of RESULT to TYPE. */
3640 tree
3642 {
3645 /* If the resulting operand is an empty statement, just return the omitted
3646 statement casted to void. */
3648 {
3651 }
3654 {
3657 }
3661 omit_one_operand_exit:
3664 }
3666 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3668 static tree
3670 tree omitted)
3671 {
3674 /* If the resulting operand is an empty statement, just return the omitted
3675 statement casted to void. */
3677 {
3680 }
3683 {
3686 }
3690 pedantic_omit_one_operand_exit:
3693 }
3695 /* Return a tree for the case when the result of an expression is RESULT
3696 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3697 of the expression but are now not needed.
3699 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3700 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3701 evaluated before OMITTED2. Otherwise, if neither has side effects,
3702 just do the conversion of RESULT to TYPE. */
3704 tree
3707 {
3711 {
3714 }
3716 {
3719 }
3722 }
3724 \f
3725 /* Return a simplified tree node for the truth-negation of ARG. This
3726 never alters ARG itself. We assume that ARG is an operation that
3727 returns a truth value (0 or 1).
3729 FIXME: one would think we would fold the result, but it causes
3730 problems with the dominator optimizer. */
3732 tree
3734 {
3739 /* If this is a comparison, we can simply invert it, except for
3740 floating-point non-equality comparisons, in which case we just
3741 enclose a TRUTH_NOT_EXPR around what we have. */
3744 {
3747 && flag_trapping_math
3759 }
3762 {
3791 /* Here we can invert either operand. We invert the first operand
3792 unless the second operand is a TRUTH_NOT_EXPR in which case our
3793 result is the XOR of the first operand with the inside of the
3794 negation of the second operand. */
3799 else
3833 {
3844 /* A COND_EXPR may have a throw as one operand, which
3845 then has void type. Just leave void operands
3846 as they are. */
3853 }
3870 CASE_CONVERT:
3872 {
3875 }
3877 /* ... fall through ... */
3908 }
3914 }
3916 /* Return a simplified tree node for the truth-negation of ARG. This
3917 never alters ARG itself. We assume that ARG is an operation that
3918 returns a truth value (0 or 1).
3920 FIXME: one would think we would fold the result, but it causes
3921 problems with the dominator optimizer. */
3923 tree
3925 {
3926 tree tem;
3933 {
3936 }
3939 }
3941 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3942 operands are another bit-wise operation with a common input. If so,
3943 distribute the bit operations to save an operation and possibly two if
3944 constants are involved. For example, convert
3945 (A | B) & (A | C) into A | (B & C)
3946 Further simplification will occur if B and C are constants.
3948 If this optimization cannot be done, 0 will be returned. */
3950 static tree
3953 {
3954 tree common;
3964 {
3968 }
3970 {
3974 }
3976 {
3980 }
3982 {
3986 }
3987 else
3995 }
3997 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3998 with code CODE. This optimization is unsafe. */
3999 static tree
4002 {
4006 /* (A / C) +- (B / C) -> (A +- B) / C. */
4016 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
4021 {
4033 }
4036 }
4037 \f
4038 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
4039 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
4041 static tree
4044 {
4048 {
4055 }
4070 }
4072 /* Optimize a bit-field compare.
4074 There are two cases: First is a compare against a constant and the
4075 second is a comparison of two items where the fields are at the same
4076 bit position relative to the start of a chunk (byte, halfword, word)
4077 large enough to contain it. In these cases we can avoid the shift
4078 implicit in bitfield extractions.
4080 For constants, we emit a compare of the shifted constant with the
4081 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4082 compared. For two fields at the same position, we do the ANDs with the
4083 similar mask and compare the result of the ANDs.
4085 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4086 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4087 are the left and right operands of the comparison, respectively.
4089 If the optimization described above can be done, we return the resulting
4090 tree. Otherwise we return zero. */
4092 static tree
4095 {
4104 tree mask;
4105 tree offset;
4107 /* Get all the information about the extractions being done. If the bit size
4108 if the same as the size of the underlying object, we aren't doing an
4109 extraction at all and so can do nothing. We also don't want to
4110 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4111 then will no longer be able to replace it. */
4119 {
4120 /* If this is not a constant, we can only do something if bit positions,
4121 sizes, and signedness are the same. */
4129 }
4131 /* See if we can find a mode to refer to this field. We should be able to,
4132 but fail if we can't. */
4141 /* Set signed and unsigned types of the precision of this mode for the
4142 shifts below. */
4146 /* Compute the bit position and size for the new reference and our offset
4147 within it. If the new reference is the same size as the original, we
4148 won't optimize anything, so return zero. */
4158 /* Make the mask to be used against the extracted field. */
4165 /* If not comparing with constant, just rework the comparison
4166 and return. */
4170 unsigned_type,
4173 mask),
4176 unsigned_type,
4179 mask));
4181 /* Otherwise, we are handling the constant case. See if the constant is too
4182 big for the field. Warn and return a tree of for 0 (false) if so. We do
4183 this not only for its own sake, but to avoid having to test for this
4184 error case below. If we didn't, we might generate wrong code.
4186 For unsigned fields, the constant shifted right by the field length should
4187 be all zero. For signed fields, the high-order bits should agree with
4188 the sign bit. */
4191 {
4196 {
4200 }
4201 }
4202 else
4203 {
4208 {
4212 }
4213 }
4215 /* Single-bit compares should always be against zero. */
4217 {
4220 }
4222 /* Make a new bitfield reference, shift the constant over the
4223 appropriate number of bits and mask it with the computed mask
4224 (in case this was a signed field). If we changed it, make a new one. */
4227 {
4230 }
4240 rhs);
4243 }
4244 \f
4245 /* Subroutine for fold_truthop: decode a field reference.
4247 If EXP is a comparison reference, we return the innermost reference.
4249 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4250 set to the starting bit number.
4252 If the innermost field can be completely contained in a mode-sized
4253 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4255 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4256 otherwise it is not changed.
4258 *PUNSIGNEDP is set to the signedness of the field.
4260 *PMASK is set to the mask used. This is either contained in a
4261 BIT_AND_EXPR or derived from the width of the field.
4263 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4265 Return 0 if this is not a component reference or is one that we can't
4266 do anything with. */
4268 static tree
4273 {
4277 tree unsigned_type;
4280 /* All the optimizations using this function assume integer fields.
4281 There are problems with FP fields since the type_for_size call
4282 below can fail for, e.g., XFmode. */
4286 /* We are interested in the bare arrangement of bits, so strip everything
4287 that doesn't affect the machine mode. However, record the type of the
4288 outermost expression if it may matter below. */
4295 {
4301 }
4310 /* If the number of bits in the reference is the same as the bitsize of
4311 the outer type, then the outer type gives the signedness. Otherwise
4312 (in case of a small bitfield) the signedness is unchanged. */
4316 /* Compute the mask to access the bitfield. */
4325 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4333 }
4335 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4336 bit positions. */
4338 static int
4340 {
4343 tree tmask;
4347 return
4354 }
4356 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4357 represents the sign bit of EXP's type. If EXP represents a sign
4358 or zero extension, also test VAL against the unextended type.
4359 The return value is the (sub)expression whose sign bit is VAL,
4360 or NULL_TREE otherwise. */
4362 static tree
4364 {
4368 tree t;
4370 /* Tree EXP must have an integral type. */
4375 /* Tree VAL must be an integer constant. */
4382 {
4389 }
4390 else
4391 {
4398 }
4400 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4401 treat VAL as if it were unsigned. */
4406 /* Handle extension from a narrower type. */
4412 }
4414 /* Subroutine for fold_truthop: determine if an operand is simple enough
4415 to be evaluated unconditionally. */
4417 static int
4419 {
4420 /* Strip any conversions that don't change the machine mode. */
4429 /* Don't regard global variables as simple. They may be
4430 allocated in ways unknown to the compiler (shared memory,
4431 #pragma weak, etc). */
4434 /* Loading a static variable is unduly expensive, but global
4435 registers aren't expensive. */
4437 }
4438 \f
4439 /* The following functions are subroutines to fold_range_test and allow it to
4440 try to change a logical combination of comparisons into a range test.
4442 For example, both
4443 X == 2 || X == 3 || X == 4 || X == 5
4444 and
4445 X >= 2 && X <= 5
4446 are converted to
4447 (unsigned) (X - 2) <= 3
4449 We describe each set of comparisons as being either inside or outside
4450 a range, using a variable named like IN_P, and then describe the
4451 range with a lower and upper bound. If one of the bounds is omitted,
4452 it represents either the highest or lowest value of the type.
4454 In the comments below, we represent a range by two numbers in brackets
4455 preceded by a "+" to designate being inside that range, or a "-" to
4456 designate being outside that range, so the condition can be inverted by
4457 flipping the prefix. An omitted bound is represented by a "-". For
4458 example, "- [-, 10]" means being outside the range starting at the lowest
4459 possible value and ending at 10, in other words, being greater than 10.
4460 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4461 always false.
4463 We set up things so that the missing bounds are handled in a consistent
4464 manner so neither a missing bound nor "true" and "false" need to be
4465 handled using a special case. */
4467 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4468 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4469 and UPPER1_P are nonzero if the respective argument is an upper bound
4470 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4471 must be specified for a comparison. ARG1 will be converted to ARG0's
4472 type if both are specified. */
4474 static tree
4477 {
4478 tree tem;
4482 /* If neither arg represents infinity, do the normal operation.
4483 Else, if not a comparison, return infinity. Else handle the special
4484 comparison rules. Note that most of the cases below won't occur, but
4485 are handled for consistency. */
4488 {
4493 }
4498 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4499 for neither. In real maths, we cannot assume open ended ranges are
4500 the same. But, this is computer arithmetic, where numbers are finite.
4501 We can therefore make the transformation of any unbounded range with
4502 the value Z, Z being greater than any representable number. This permits
4503 us to treat unbounded ranges as equal. */
4507 {
4528 }
4531 }
4532 \f
4533 /* Given EXP, a logical expression, set the range it is testing into
4534 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4535 actually being tested. *PLOW and *PHIGH will be made of the same
4536 type as the returned expression. If EXP is not a comparison, we
4537 will most likely not be returning a useful value and range. Set
4538 *STRICT_OVERFLOW_P to true if the return value is only valid
4539 because signed overflow is undefined; otherwise, do not change
4540 *STRICT_OVERFLOW_P. */
4542 tree
4545 {
4553 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4554 and see if we can refine the range. Some of the cases below may not
4555 happen, but it doesn't seem worth worrying about this. We "continue"
4556 the outer loop when we've changed something; otherwise we "break"
4557 the switch, which will "break" the while. */
4563 {
4568 {
4580 }
4583 {
4590 /* We can only do something if the range is testing for zero
4591 and if the second operand is an integer constant. Note that
4592 saying something is "in" the range we make is done by
4593 complementing IN_P since it will set in the initial case of
4594 being not equal to zero; "out" is leaving it alone. */
4601 {
4622 }
4624 /* If this is an unsigned comparison, we also know that EXP is
4625 greater than or equal to zero. We base the range tests we make
4626 on that fact, so we record it here so we can parse existing
4627 range tests. We test arg0_type since often the return type
4628 of, e.g. EQ_EXPR, is boolean. */
4630 {
4634 NULL_TREE))
4639 /* If the high bound is missing, but we have a nonzero low
4640 bound, reverse the range so it goes from zero to the low bound
4641 minus 1. */
4643 {
4648 }
4649 }
4655 /* (-x) IN [a,b] -> x in [-b, -a] */
4667 /* ~ X -> -X - 1 */
4677 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4678 move a constant to the other side. */
4683 /* If EXP is signed, any overflow in the computation is undefined,
4684 so we don't worry about it so long as our computations on
4685 the bounds don't overflow. For unsigned, overflow is defined
4686 and this is exactly the right thing. */
4698 /* Check for an unsigned range which has wrapped around the maximum
4699 value thus making n_high < n_low, and normalize it. */
4701 {
4707 /* If the range is of the form +/- [ x+1, x ], we won't
4708 be able to normalize it. But then, it represents the
4709 whole range or the empty set, so make it
4710 +/- [ -, - ]. */
4714 else
4716 }
4717 else
4741 /* If we're converting arg0 from an unsigned type, to exp,
4742 a signed type, we will be doing the comparison as unsigned.
4743 The tests above have already verified that LOW and HIGH
4744 are both positive.
4746 So we have to ensure that we will handle large unsigned
4747 values the same way that the current signed bounds treat
4748 negative values. */
4751 {
4752 tree high_positive;
4753 tree equiv_type;
4754 /* For fixed-point modes, we need to pass the saturating flag
4755 as the 2nd parameter. */
4760 else
4764 /* A range without an upper bound is, naturally, unbounded.
4765 Since convert would have cropped a very large value, use
4766 the max value for the destination type. */
4767 high_positive
4774 high_positive),
4777 /* If the low bound is specified, "and" the range with the
4778 range for which the original unsigned value will be
4779 positive. */
4781 {
4785 integer_zero_node),
4786 high_positive))
4790 }
4791 else
4792 {
4793 /* Otherwise, "or" the range with the range of the input
4794 that will be interpreted as negative. */
4798 integer_zero_node),
4799 high_positive))
4803 }
4804 }
4812 }
4815 }
4817 /* If EXP is a constant, we can evaluate whether this is true or false. */
4819 {
4826 }
4830 }
4831 \f
4832 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4833 type, TYPE, return an expression to test if EXP is in (or out of, depending
4834 on IN_P) the range. Return 0 if the test couldn't be created. */
4836 tree
4839 {
4842 #ifdef HAVE_canonicalize_funcptr_for_compare
4843 /* Disable this optimization for function pointer expressions
4844 on targets that require function pointer canonicalization. */
4849 #endif
4852 {
4858 }
4876 {
4878 {
4882 }
4884 }
4886 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4888 {
4890 HOST_WIDE_INT hi;
4895 {
4898 }
4899 else
4900 {
4903 }
4906 {
4908 {
4911 etype
4913 else
4916 }
4919 }
4920 }
4922 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4923 This requires wrap-around arithmetics for the type of the expression.
4924 First make sure that arithmetics in this type is valid, then make sure
4925 that it wraps around. */
4931 {
4934 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4935 for the type in question, as we rely on this here. */
4945 else
4947 }
4957 {
4959 {
4966 }
4968 }
4976 }
4977 \f
4978 /* Return the predecessor of VAL in its type, handling the infinite case. */
4980 static tree
4982 {
4988 else
4990 }
4992 /* Return the successor of VAL in its type, handling the infinite case. */
4994 static tree
4996 {
5002 else
5004 }
5006 /* Given two ranges, see if we can merge them into one. Return 1 if we
5007 can, 0 if we can't. Set the output range into the specified parameters. */
5009 bool
5012 {
5016 tree tem;
5026 /* Make range 0 be the range that starts first, or ends last if they
5027 start at the same value. Swap them if it isn't. */
5030 || (lowequal
5033 {
5037 }
5039 /* Now flag two cases, whether the ranges are disjoint or whether the
5040 second range is totally subsumed in the first. Note that the tests
5041 below are simplified by the ones above. */
5047 /* We now have four cases, depending on whether we are including or
5048 excluding the two ranges. */
5050 {
5051 /* If they don't overlap, the result is false. If the second range
5052 is a subset it is the result. Otherwise, the range is from the start
5053 of the second to the end of the first. */
5058 else
5060 }
5063 {
5064 /* If they don't overlap, the result is the first range. If they are
5065 equal, the result is false. If the second range is a subset of the
5066 first, and the ranges begin at the same place, we go from just after
5067 the end of the second range to the end of the first. If the second
5068 range is not a subset of the first, or if it is a subset and both
5069 ranges end at the same place, the range starts at the start of the
5070 first range and ends just before the second range.
5071 Otherwise, we can't describe this as a single range. */
5077 {
5082 {
5083 /* We are in the weird situation where high0 > high1 but
5084 high1 has no successor. Punt. */
5086 }
5087 }
5089 {
5094 {
5095 /* low0 < low1 but low1 has no predecessor. Punt. */
5097 }
5098 }
5099 else
5101 }
5104 {
5105 /* If they don't overlap, the result is the second range. If the second
5106 is a subset of the first, the result is false. Otherwise,
5107 the range starts just after the first range and ends at the
5108 end of the second. */
5113 else
5114 {
5119 {
5120 /* high1 > high0 but high0 has no successor. Punt. */
5122 }
5123 }
5124 }
5126 else
5127 {
5128 /* The case where we are excluding both ranges. Here the complex case
5129 is if they don't overlap. In that case, the only time we have a
5130 range is if they are adjacent. If the second is a subset of the
5131 first, the result is the first. Otherwise, the range to exclude
5132 starts at the beginning of the first range and ends at the end of the
5133 second. */
5135 {
5140 else
5141 {
5142 /* Canonicalize - [min, x] into - [-, x]. */
5145 {
5150 /* FALLTHROUGH */
5163 }
5165 /* Canonicalize - [x, max] into - [x, -]. */
5168 {
5173 /* FALLTHROUGH */
5188 }
5190 /* The ranges might be also adjacent between the maximum and
5191 minimum values of the given type. For
5192 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5193 return + [x + 1, y - 1]. */
5195 {
5202 }
5203 else
5205 }
5206 }
5209 else
5211 }
5215 }
5216 \f
5218 /* Subroutine of fold, looking inside expressions of the form
5219 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5220 of the COND_EXPR. This function is being used also to optimize
5221 A op B ? C : A, by reversing the comparison first.
5223 Return a folded expression whose code is not a COND_EXPR
5224 anymore, or NULL_TREE if no folding opportunity is found. */
5226 static tree
5229 {
5234 tree tem;
5239 /* If we have A op 0 ? A : -A, consider applying the following
5240 transformations:
5242 A == 0? A : -A same as -A
5243 A != 0? A : -A same as A
5244 A >= 0? A : -A same as abs (A)
5245 A > 0? A : -A same as abs (A)
5246 A <= 0? A : -A same as -abs (A)
5247 A < 0? A : -A same as -abs (A)
5249 None of these transformations work for modes with signed
5250 zeros. If A is +/-0, the first two transformations will
5251 change the sign of the result (from +0 to -0, or vice
5252 versa). The last four will fix the sign of the result,
5253 even though the original expressions could be positive or
5254 negative, depending on the sign of A.
5256 Note that all these transformations are correct if A is
5257 NaN, since the two alternatives (A and -A) are also NaNs. */
5264 /* In the case that A is of the form X-Y, '-A' (arg2) may
5265 have already been folded to Y-X, check for that. */
5273 {
5287 /* Fall through. */
5309 }
5311 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5312 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5313 both transformations are correct when A is NaN: A != 0
5314 is then true, and A == 0 is false. */
5318 {
5323 }
5325 /* Try some transformations of A op B ? A : B.
5327 A == B? A : B same as B
5328 A != B? A : B same as A
5329 A >= B? A : B same as max (A, B)
5330 A > B? A : B same as max (B, A)
5331 A <= B? A : B same as min (A, B)
5332 A < B? A : B same as min (B, A)
5334 As above, these transformations don't work in the presence
5335 of signed zeros. For example, if A and B are zeros of
5336 opposite sign, the first two transformations will change
5337 the sign of the result. In the last four, the original
5338 expressions give different results for (A=+0, B=-0) and
5339 (A=-0, B=+0), but the transformed expressions do not.
5341 The first two transformations are correct if either A or B
5342 is a NaN. In the first transformation, the condition will
5343 be false, and B will indeed be chosen. In the case of the
5344 second transformation, the condition A != B will be true,
5345 and A will be chosen.
5347 The conversions to max() and min() are not correct if B is
5348 a number and A is not. The conditions in the original
5349 expressions will be false, so all four give B. The min()
5350 and max() versions would give a NaN instead. */
5353 /* Avoid these transformations if the COND_EXPR may be used
5354 as an lvalue in the C++ front-end. PR c++/19199. */
5355 && (in_gimple_form
5360 {
5365 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5367 {
5371 }
5374 {
5383 /* In C++ a ?: expression can be an lvalue, so put the
5384 operand which will be used if they are equal first
5385 so that we can convert this back to the
5386 corresponding COND_EXPR. */
5388 {
5397 }
5404 {
5413 }
5428 }
5429 }
5431 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5432 we might still be able to simplify this. For example,
5433 if C1 is one less or one more than C2, this might have started
5434 out as a MIN or MAX and been transformed by this function.
5435 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5441 {
5445 /* We can replace A with C1 in this case. */
5450 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5451 MIN_EXPR, to preserve the signedness of the comparison. */
5453 OEP_ONLY_CONST)
5457 OEP_ONLY_CONST))
5458 {
5461 arg2));
5464 }
5468 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5469 as above. */
5471 OEP_ONLY_CONST)
5475 OEP_ONLY_CONST))
5476 {
5479 arg2));
5482 }
5486 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5487 MAX_EXPR, to preserve the signedness of the comparison. */
5489 OEP_ONLY_CONST)
5493 OEP_ONLY_CONST))
5494 {
5497 arg2));
5499 }
5503 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5505 OEP_ONLY_CONST)
5509 OEP_ONLY_CONST))
5510 {
5513 arg2));
5515 }
5521 }
5524 }
5527 \f
5528 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5529 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5530 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5531 false) >= 2)
5532 #endif
5534 /* EXP is some logical combination of boolean tests. See if we can
5535 merge it into some range test. Return the new tree if so. */
5537 static tree
5540 {
5548 tree tem;
5552 /* If this is an OR operation, invert both sides; we will invert
5553 again at the end. */
5557 /* If both expressions are the same, if we can merge the ranges, and we
5558 can build the range test, return it or it inverted. If one of the
5559 ranges is always true or always false, consider it to be the same
5560 expression as the other. */
5568 {
5572 }
5574 /* On machines where the branch cost is expensive, if this is a
5575 short-circuited branch and the underlying object on both sides
5576 is the same, make a non-short-circuit operation. */
5582 {
5583 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5584 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5585 which cases we can't do this. */
5587 {
5593 }
5597 {
5606 {
5609 WARN_STRICT_OVERFLOW_COMPARISON);
5615 }
5616 }
5617 }
5620 }
5621 \f
5622 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5623 bit value. Arrange things so the extra bits will be set to zero if and
5624 only if C is signed-extended to its full width. If MASK is nonzero,
5625 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5627 static tree
5629 {
5632 tree temp;
5637 /* We work by getting just the sign bit into the low-order bit, then
5638 into the high-order bit, then sign-extend. We then XOR that value
5639 with C. */
5643 /* We must use a signed type in order to get an arithmetic right shift.
5644 However, we must also avoid introducing accidental overflows, so that
5645 a subsequent call to integer_zerop will work. Hence we must
5646 do the type conversion here. At this point, the constant is either
5647 zero or one, and the conversion to a signed type can never overflow.
5648 We could get an overflow if this conversion is done anywhere else. */
5658 /* If necessary, convert the type back to match the type of C. */
5664 }
5665 \f
5666 /* Find ways of folding logical expressions of LHS and RHS:
5667 Try to merge two comparisons to the same innermost item.
5668 Look for range tests like "ch >= '0' && ch <= '9'".
5669 Look for combinations of simple terms on machines with expensive branches
5670 and evaluate the RHS unconditionally.
5672 For example, if we have p->a == 2 && p->b == 4 and we can make an
5673 object large enough to span both A and B, we can do this with a comparison
5674 against the object ANDed with the a mask.
5676 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5677 operations to do this with one comparison.
5679 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5680 function and the one above.
5682 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5683 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5685 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5686 two operands.
5688 We return the simplified tree or 0 if no optimization is possible. */
5690 static tree
5693 {
5694 /* If this is the "or" of two comparisons, we can do something if
5695 the comparisons are NE_EXPR. If this is the "and", we can do something
5696 if the comparisons are EQ_EXPR. I.e.,
5697 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5699 WANTED_CODE is this operation code. For single bit fields, we can
5700 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5701 comparison for one-bit fields. */
5723 /* Start by getting the comparison codes. Fail if anything is volatile.
5724 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5725 it were surrounded with a NE_EXPR. */
5734 {
5738 }
5741 {
5745 }
5756 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5759 {
5760 tree result;
5763 {
5768 }
5771 {
5777 }
5778 }
5783 /* If the RHS can be evaluated unconditionally and its operands are
5784 simple, it wins to evaluate the RHS unconditionally on machines
5785 with expensive branches. In this case, this isn't a comparison
5786 that can be merged. Avoid doing this if the RHS is a floating-point
5787 comparison since those can trap. */
5794 {
5795 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5801 {
5807 }
5809 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5815 {
5821 }
5824 {
5826 {
5829 }
5831 }
5832 }
5834 /* See if the comparisons can be merged. Then get all the parameters for
5835 each side. */
5859 /* It must be true that the inner operation on the lhs of each
5860 comparison must be the same if we are to be able to do anything.
5861 Then see if we have constants. If not, the same must be true for
5862 the rhs's. */
5873 else
5876 /* If either comparison code is not correct for our logical operation,
5877 fail. However, we can convert a one-bit comparison against zero into
5878 the opposite comparison against that bit being set in the field. */
5882 {
5884 {
5885 /* Make the left operand unsigned, since we are only interested
5886 in the value of one bit. Otherwise we are doing the wrong
5887 thing below. */
5890 }
5891 else
5893 }
5895 /* This is analogous to the code for l_const above. */
5897 {
5899 {
5902 }
5903 else
5905 }
5907 /* See if we can find a mode that contains both fields being compared on
5908 the left. If we can't, fail. Otherwise, update all constants and masks
5909 to be relative to a field of that size. */
5914 volatilep);
5924 {
5927 }
5935 {
5943 {
5947 }
5948 }
5950 {
5958 {
5962 }
5963 }
5965 /* If the right sides are not constant, do the same for it. Also,
5966 disallow this optimization if a size or signedness mismatch occurs
5967 between the left and right sides. */
5969 {
5972 /* Make sure the two fields on the right
5973 correspond to the left without being swapped. */
5981 volatilep);
5991 {
5994 }
6003 /* Make a mask that corresponds to both fields being compared.
6004 Do this for both items being compared. If the operands are the
6005 same size and the bits being compared are in the same position
6006 then we can do this by masking both and comparing the masked
6007 results. */
6011 {
6024 }
6026 /* There is still another way we can do something: If both pairs of
6027 fields being compared are adjacent, we may be able to make a wider
6028 field containing them both.
6030 Note that we still must mask the lhs/rhs expressions. Furthermore,
6031 the mask must be shifted to account for the shift done by
6032 make_bit_field_ref. */
6037 {
6038 tree type;
6052 /* Convert to the smaller type before masking out unwanted bits. */
6055 {
6057 {
6061 }
6063 {
6067 }
6068 }
6078 }
6081 }
6083 /* Handle the case of comparisons with constants. If there is something in
6084 common between the masks, those bits of the constants must be the same.
6085 If not, the condition is always false. Test for this to avoid generating
6086 incorrect code below. */
6091 {
6093 {
6096 }
6097 else
6098 {
6101 }
6102 }
6104 /* Construct the expression we will return. First get the component
6105 reference we will make. Unless the mask is all ones the width of
6106 that field, perform the mask operation. Then compare with the
6107 merged constant. */
6113 {
6116 }
6121 fold_truthop_exit:
6124 }
6125 \f
6126 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
6127 constant. */
6129 static tree
6132 {
6135 tree comp_const;
6136 tree minmax_const;
6138 tree inner;
6149 /* If something does not permit us to optimize, return the original tree. */
6157 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6158 and GT_EXPR, doing the rest with recursive calls using logical
6159 simplifications. */
6161 {
6163 {
6164 tree tem
6171 }
6174 return
6176 optimize_minmax_comparison
6178 optimize_minmax_comparison
6183 /* MAX (X, 0) == 0 -> X <= 0 */
6187 /* MAX (X, 0) == 5 -> X == 5 */
6191 /* MAX (X, 0) == -1 -> false */
6195 /* MIN (X, 0) == 0 -> X >= 0 */
6199 /* MIN (X, 0) == 5 -> false */
6202 else
6203 /* MIN (X, 0) == -1 -> X == -1 */
6208 /* MAX (X, 0) > 0 -> X > 0
6209 MAX (X, 0) > 5 -> X > 5 */
6213 /* MAX (X, 0) > -1 -> true */
6217 /* MIN (X, 0) > 0 -> false
6218 MIN (X, 0) > 5 -> false */
6221 else
6222 /* MIN (X, 0) > -1 -> X > -1 */
6227 }
6228 }
6229 \f
6230 /* T is an integer expression that is being multiplied, divided, or taken a
6231 modulus (CODE says which and what kind of divide or modulus) by a
6232 constant C. See if we can eliminate that operation by folding it with
6233 other operations already in T. WIDE_TYPE, if non-null, is a type that
6234 should be used for the computation if wider than our type.
6236 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6237 (X * 2) + (Y * 4). We must, however, be assured that either the original
6238 expression would not overflow or that overflow is undefined for the type
6239 in the language in question.
6241 If we return a non-null expression, it is an equivalent form of the
6242 original computation, but need not be in the original type.
6244 We set *STRICT_OVERFLOW_P to true if the return values depends on
6245 signed overflow being undefined. Otherwise we do not change
6246 *STRICT_OVERFLOW_P. */
6248 static tree
6251 {
6252 /* To avoid exponential search depth, refuse to allow recursion past
6253 three levels. Beyond that (1) it's highly unlikely that we'll find
6254 something interesting and (2) we've probably processed it before
6255 when we built the inner expression. */
6258 tree ret;
6263 depth++;
6265 depth--;
6268 }
6270 static tree
6273 {
6284 /* Don't deal with constants of zero here; they confuse the code below. */
6294 /* Note that we need not handle conditional operations here since fold
6295 already handles those cases. So just do arithmetic here. */
6297 {
6299 /* For a constant, we can always simplify if we are a multiply
6300 or (for divide and modulus) if it is a multiple of our constant. */
6308 /* If op0 is an expression ... */
6314 /* ... and has wrapping overflow, and its type is smaller
6315 than ctype, then we cannot pass through as widening. */
6321 /* ... or this is a truncation (t is narrower than op0),
6322 then we cannot pass through this narrowing. */
6325 /* ... or signedness changes for division or modulus,
6326 then we cannot pass through this conversion. */
6330 /* ... or has undefined overflow while the converted to
6331 type has not, we cannot do the operation in the inner type
6332 as that would introduce undefined overflow. */
6337 /* Pass the constant down and see if we can make a simplification. If
6338 we can, replace this expression with the inner simplification for
6339 possible later conversion to our or some other type. */
6344 code == MULT_EXPR
6346 strict_overflow_p))))
6351 /* If widening the type changes it from signed to unsigned, then we
6352 must avoid building ABS_EXPR itself as unsigned. */
6354 {
6358 {
6361 }
6363 }
6364 /* If the constant is negative, we cannot simplify this. */
6367 /* FALLTHROUGH */
6375 /* If widening the type changes the signedness, then we can't perform
6376 this optimization as that changes the result. */
6380 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6386 {
6393 }
6397 /* If the second operand is constant, this is a multiplication
6398 or floor division, by a power of two, so we can treat it that
6399 way unless the multiplier or divisor overflows. Signed
6400 left-shift overflow is implementation-defined rather than
6401 undefined in C90, so do not convert signed left shift into
6402 multiplication. */
6405 /* const_binop may not detect overflow correctly,
6406 so check for it explicitly here. */
6411 size_one_node,
6416 ctype,
6418 t1),
6423 /* See if we can eliminate the operation on both sides. If we can, we
6424 can return a new PLUS or MINUS. If we can't, the only remaining
6425 cases where we can do anything are if the second operand is a
6426 constant. */
6432 /* If not multiplication, we can only do this if both operands
6433 are divisible by c. */
6436 {
6441 }
6443 /* If this was a subtraction, negate OP1 and set it to be an addition.
6444 This simplifies the logic below. */
6451 /* If either OP1 or C are negative, this optimization is not safe for
6452 some of the division and remainder types while for others we need
6453 to change the code. */
6455 {
6463 }
6465 /* If it's a multiply or a division/modulus operation of a multiple
6466 of our constant, do the operation and verify it doesn't overflow. */
6469 {
6472 /* We allow the constant to overflow with wrapping semantics. */
6476 }
6477 else
6480 /* If we have an unsigned type is not a sizetype, we cannot widen
6481 the operation since it will change the result if the original
6482 computation overflowed. */
6488 /* If we were able to eliminate our operation from the first side,
6489 apply our operation to the second side and reform the PLUS. */
6493 /* The last case is if we are a multiply. In that case, we can
6494 apply the distributive law to commute the multiply and addition
6495 if the multiplication of the constants doesn't overflow. */
6501 op1);
6506 /* We have a special case here if we are doing something like
6507 (C * 8) % 4 since we know that's zero. */
6510 /* If the multiplication can overflow we cannot optimize this.
6511 ??? Until we can properly mark individual operations as
6512 not overflowing we need to treat sizetype special here as
6513 stor-layout relies on this opimization to make
6514 DECL_FIELD_BIT_OFFSET always a constant. */
6520 {
6523 }
6525 /* ... fall through ... */
6529 /* If we can extract our operation from the LHS, do so and return a
6530 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6531 do something only if the second operand is a constant. */
6545 /* If these are the same operation types, we can associate them
6546 assuming no overflow. */
6559 /* If these operations "cancel" each other, we have the main
6560 optimizations of this pass, which occur when either constant is a
6561 multiple of the other, in which case we replace this with either an
6562 operation or CODE or TCODE.
6564 If we have an unsigned type that is not a sizetype, we cannot do
6565 this since it will change the result if the original computation
6566 overflowed. */
6574 {
6576 {
6583 }
6585 {
6592 }
6593 }
6598 }
6601 }
6602 \f
6603 /* Return a node which has the indicated constant VALUE (either 0 or
6604 1), and is of the indicated TYPE. */
6606 tree
6608 {
6613 else
6615 }
6618 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6619 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6620 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6621 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6622 COND is the first argument to CODE; otherwise (as in the example
6623 given here), it is the second argument. TYPE is the type of the
6624 original expression. Return NULL_TREE if no simplification is
6625 possible. */
6627 static tree
6632 {
6639 /* This transformation is only worthwhile if we don't have to wrap
6640 arg in a SAVE_EXPR, and the operation can be simplified on at least
6641 one of the branches once its pushed inside the COND_EXPR. */
6646 {
6650 /* If this operand throws an expression, then it does not make
6651 sense to try to perform a logical or arithmetic operation
6652 involving it. */
6657 }
6658 else
6659 {
6664 }
6668 {
6672 else
6674 }
6676 {
6680 else
6682 }
6686 }
6688 \f
6689 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6691 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6692 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6693 ADDEND is the same as X.
6695 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6696 and finite. The problematic cases are when X is zero, and its mode
6697 has signed zeros. In the case of rounding towards -infinity,
6698 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6699 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6701 bool
6703 {
6707 /* Don't allow the fold with -fsignaling-nans. */
6711 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6715 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6720 /* The mode has signed zeros, and we have to honor their sign.
6721 In this situation, there is only one case we can return true for.
6722 X - 0 is the same as X unless rounding towards -infinity is
6723 supported. */
6725 }
6727 /* Subroutine of fold() that checks comparisons of built-in math
6728 functions against real constants.
6730 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6731 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6732 is the type of the result and ARG0 and ARG1 are the operands of the
6733 comparison. ARG1 must be a TREE_REAL_CST.
6735 The function returns the constant folded tree if a simplification
6736 can be made, and NULL_TREE otherwise. */
6738 static tree
6742 {
6743 REAL_VALUE_TYPE c;
6746 {
6752 {
6753 /* sqrt(x) < y is always false, if y is negative. */
6757 /* sqrt(x) > y is always true, if y is negative and we
6758 don't care about NaNs, i.e. negative values of x. */
6762 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6765 }
6767 {
6768 REAL_VALUE_TYPE c2;
6774 {
6775 /* sqrt(x) > y is x == +Inf, when y is very large. */
6780 /* sqrt(x) > y is always false, when y is very large
6781 and we don't care about infinities. */
6783 }
6785 /* sqrt(x) > c is the same as x > c*c. */
6788 }
6790 {
6791 REAL_VALUE_TYPE c2;
6797 {
6798 /* sqrt(x) < y is always true, when y is a very large
6799 value and we don't care about NaNs or Infinities. */
6803 /* sqrt(x) < y is x != +Inf when y is very large and we
6804 don't care about NaNs. */
6809 /* sqrt(x) < y is x >= 0 when y is very large and we
6810 don't care about Infinities. */
6815 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6824 dconst0)),
6827 c2)));
6828 }
6830 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6835 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6838 {
6843 dconst0)),
6846 c2)));
6847 }
6848 }
6849 }
6852 }
6854 /* Subroutine of fold() that optimizes comparisons against Infinities,
6855 either +Inf or -Inf.
6857 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6858 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6859 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6861 The function returns the constant folded tree if a simplification
6862 can be made, and NULL_TREE otherwise. */
6864 static tree
6867 {
6869 REAL_VALUE_TYPE max;
6870 tree temp;
6875 /* For negative infinity swap the sense of the comparison. */
6881 {
6883 /* x > +Inf is always false, if with ignore sNANs. */
6889 /* x <= +Inf is always true, if we don't case about NaNs. */
6893 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6896 {
6899 }
6904 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6910 /* x < +Inf is always equal to x <= DBL_MAX. */
6916 /* x != +Inf is always equal to !(x > DBL_MAX). */
6928 }
6931 }
6933 /* Subroutine of fold() that optimizes comparisons of a division by
6934 a nonzero integer constant against an integer constant, i.e.
6935 X/C1 op C2.
6937 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6938 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6939 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6941 The function returns the constant folded tree if a simplification
6942 can be made, and NULL_TREE otherwise. */
6944 static tree
6947 {
6952 HOST_WIDE_INT hpart;
6957 /* We have to do this the hard way to detect unsigned overflow.
6958 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6969 {
6974 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6982 }
6984 {
6988 {
7007 }
7008 }
7009 else
7010 {
7011 /* A negative divisor reverses the relational operators. */
7017 {
7036 }
7037 }
7040 {
7061 {
7064 }
7069 {
7072 }
7077 {
7080 }
7085 {
7088 }
7093 }
7096 }
7099 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7100 equality/inequality test, then return a simplified form of the test
7101 using a sign testing. Otherwise return NULL. TYPE is the desired
7102 result type. */
7104 static tree
7107 tree result_type)
7108 {
7109 /* If this is testing a single bit, we can optimize the test. */
7113 {
7114 /* If we have (A & C) != 0 where C is the sign bit of A, convert
7115 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
7119 /* This is only a win if casting to a signed type is cheap,
7120 i.e. when arg00's type is not a partial mode. */
7123 {
7126 result_type,
7129 }
7130 }
7133 }
7135 /* If CODE with arguments ARG0 and ARG1 represents a single bit
7136 equality/inequality test, then return a simplified form of
7137 the test using shifts and logical operations. Otherwise return
7138 NULL. TYPE is the desired result type. */
7140 tree
7143 {
7144 /* If this is testing a single bit, we can optimize the test. */
7148 {
7157 /* First, see if we can fold the single bit test into a sign-bit
7158 test. */
7160 result_type);
7164 /* Otherwise we have (A & C) != 0 where C is a single bit,
7165 convert that into ((A >> C2) & 1). Where C2 = log2(C).
7166 Similarly for (A & C) == 0. */
7168 /* If INNER is a right shift of a constant and it plus BITNUM does
7169 not overflow, adjust BITNUM and INNER. */
7176 {
7179 }
7181 /* If we are going to be able to omit the AND below, we must do our
7182 operations as unsigned. If we must use the AND, we have a choice.
7183 Normally unsigned is faster, but for some machines signed is. */
7184 #ifdef LOAD_EXTEND_OP
7187 #else
7189 #endif
7205 /* Put the AND last so it can combine with more things. */
7208 /* Make sure to return the proper type. */
7212 }
7214 }
7216 /* Check whether we are allowed to reorder operands arg0 and arg1,
7217 such that the evaluation of arg1 occurs before arg0. */
7219 static bool
7221 {
7228 }
7230 /* Test whether it is preferable two swap two operands, ARG0 and
7231 ARG1, for example because ARG0 is an integer constant and ARG1
7232 isn't. If REORDER is true, only recommend swapping if we can
7233 evaluate the operands in reverse order. */
7235 bool
7237 {
7273 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7274 for commutative and comparison operators. Ensuring a canonical
7275 form allows the optimizers to find additional redundancies without
7276 having to explicitly check for both orderings. */
7282 /* Put SSA_NAMEs last. */
7288 /* Put variables last. */
7295 }
7297 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7298 ARG0 is extended to a wider type. */
7300 static tree
7303 {
7305 tree arg1_unw;
7314 #ifdef HAVE_canonicalize_funcptr_for_compare
7315 /* Disable this optimization if we're casting a function pointer
7316 type on targets that require function pointer canonicalization. */
7321 #endif
7328 /* If possible, express the comparison in the shorter mode. */
7348 /* If we are comparing with the integer that does not fit into the range
7349 of the shorter type, the result is known. */
7360 {
7387 }
7390 }
7392 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7393 ARG0 just the signedness is changed. */
7395 static tree
7398 {
7399 tree arg0_inner;
7409 #ifdef HAVE_canonicalize_funcptr_for_compare
7410 /* Disable this optimization if we're casting a function pointer
7411 type on targets that require function pointer canonicalization. */
7416 #endif
7436 else
7440 }
7442 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7443 step of the array. Reconstructs s and delta in the case of s *
7444 delta being an integer constant (and thus already folded). ADDR is
7445 the address. MULT is the multiplicative expression. If the
7446 function succeeds, the new address expression is returned.
7447 Otherwise NULL_TREE is returned. LOC is the location of the
7448 resulting expression. */
7450 static tree
7452 {
7456 tree itype;
7459 /* Strip the nops that might be added when converting op1 to sizetype. */
7462 /* Canonicalize op1 into a possibly non-constant delta
7463 and an INTEGER_CST s. */
7465 {
7472 {
7475 }
7477 {
7480 }
7481 else
7483 }
7485 {
7488 }
7489 else
7490 {
7491 /* Simulate we are delta * 1. */
7494 }
7497 {
7499 {
7500 /* Remember if this was a multi-dimensional array. */
7513 {
7516 }
7517 else
7518 {
7519 /* Try if delta is a multiple of step. */
7524 }
7526 /* Only fold here if we can verify we do not overflow one
7527 dimension of a multi-dimensional array. */
7529 {
7530 tree tmp;
7546 }
7549 }
7550 else
7555 }
7557 /* We found the suitable array reference. So copy everything up to it,
7558 and replace the index. */
7566 {
7570 }
7578 }
7581 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7582 means A >= Y && A != MAX, but in this case we know that
7583 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7585 static tree
7587 {
7594 else
7603 {
7606 }
7608 {
7611 }
7612 else
7619 {
7620 /* Convert the pointer types into integer before taking the difference. */
7624 }
7625 else
7632 }
7634 /* Fold a sum or difference of at least one multiplication.
7635 Returns the folded tree or NULL if no simplification could be made. */
7637 static tree
7640 {
7644 /* (A * C) +- (B * C) -> (A+-B) * C.
7645 (A * C) +- A -> A * (C+-1).
7646 We are most concerned about the case where C is a constant,
7647 but other combinations show up during loop reduction. Since
7648 it is not difficult, try all four possibilities. */
7651 {
7654 }
7656 {
7659 }
7660 else
7661 {
7662 /* We cannot generate constant 1 for fract. */
7667 }
7669 {
7672 }
7674 {
7676 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7677 the purpose of this canonicalization. */
7681 {
7684 }
7685 else
7687 }
7688 else
7689 {
7690 /* We cannot generate constant 1 for fract. */
7695 }
7707 /* No identical multiplicands; see if we can find a common
7708 power-of-two factor in non-power-of-two multiplies. This
7709 can help in multi-dimensional array access. */
7712 {
7715 tree maybe_same;
7719 /* Move min of absolute values to int11. */
7722 {
7727 }
7728 else
7732 /* The remainder should not be a constant, otherwise we
7733 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7734 increased the number of multiplications necessary. */
7736 {
7744 }
7745 }
7755 }
7757 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7758 specified by EXPR into the buffer PTR of length LEN bytes.
7759 Return the number of bytes placed in the buffer, or zero
7760 upon failure. */
7762 static int
7764 {
7775 {
7779 else
7784 {
7791 else
7793 }
7794 else
7797 }
7799 }
7802 /* Subroutine of native_encode_expr. Encode the REAL_CST
7803 specified by EXPR into the buffer PTR of length LEN bytes.
7804 Return the number of bytes placed in the buffer, or zero
7805 upon failure. */
7807 static int
7809 {
7815 /* There are always 32 bits in each long, no matter the size of
7816 the hosts long. We handle floating point representations with
7817 up to 192 bits. */
7828 {
7833 {
7840 else
7842 }
7843 else
7846 }
7848 }
7850 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7851 specified by EXPR into the buffer PTR of length LEN bytes.
7852 Return the number of bytes placed in the buffer, or zero
7853 upon failure. */
7855 static int
7857 {
7859 tree part;
7870 }
7873 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7874 specified by EXPR into the buffer PTR of length LEN bytes.
7875 Return the number of bytes placed in the buffer, or zero
7876 upon failure. */
7878 static int
7880 {
7890 {
7892 {
7895 }
7896 else
7900 {
7903 }
7904 else
7905 {
7909 }
7911 }
7913 }
7916 /* Subroutine of native_encode_expr. Encode the STRING_CST
7917 specified by EXPR into the buffer PTR of length LEN bytes.
7918 Return the number of bytes placed in the buffer, or zero
7919 upon failure. */
7921 static int
7923 {
7925 HOST_WIDE_INT total_bytes;
7936 {
7940 }
7941 else
7944 }
7947 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7948 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7949 buffer PTR of length LEN bytes. Return the number of bytes
7950 placed in the buffer, or zero upon failure. */
7952 int
7954 {
7956 {
7974 }
7975 }
7978 /* Subroutine of native_interpret_expr. Interpret the contents of
7979 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7980 If the buffer cannot be interpreted, return NULL_TREE. */
7982 static tree
7984 {
7998 {
8001 {
8008 else
8010 }
8011 else
8017 else
8020 }
8023 }
8026 /* Subroutine of native_interpret_expr. Interpret the contents of
8027 the buffer PTR of length LEN as a REAL_CST of type TYPE.
8028 If the buffer cannot be interpreted, return NULL_TREE. */
8030 static tree
8032 {
8037 /* There are always 32 bits in each long, no matter the size of
8038 the hosts long. We handle floating point representations with
8039 up to 192 bits. */
8040 REAL_VALUE_TYPE r;
8051 {
8054 {
8061 else
8063 }
8064 else
8069 }
8073 }
8076 /* Subroutine of native_interpret_expr. Interpret the contents of
8077 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
8078 If the buffer cannot be interpreted, return NULL_TREE. */
8080 static tree
8082 {
8097 }
8100 /* Subroutine of native_interpret_expr. Interpret the contents of
8101 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
8102 If the buffer cannot be interpreted, return NULL_TREE. */
8104 static tree
8106 {
8118 {
8123 }
8125 }
8128 /* Subroutine of fold_view_convert_expr. Interpret the contents of
8129 the buffer PTR of length LEN as a constant of type TYPE. For
8130 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
8131 we return a REAL_CST, etc... If the buffer cannot be interpreted,
8132 return NULL_TREE. */
8134 tree
8136 {
8138 {
8155 }
8156 }
8159 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
8160 TYPE at compile-time. If we're unable to perform the conversion
8161 return NULL_TREE. */
8163 static tree
8165 {
8166 /* We support up to 512-bit values (for V8DFmode). */
8170 /* Check that the host and target are sane. */
8179 }
8181 /* Build an expression for the address of T. Folds away INDIRECT_REF
8182 to avoid confusing the gimplify process. */
8184 tree
8186 {
8187 /* The size of the object is not relevant when talking about its address. */
8191 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8194 {
8198 {
8201 }
8202 }
8204 {
8209 }
8210 else
8211 {
8214 }
8217 }
8219 /* Build an expression for the address of T. */
8221 tree
8223 {
8227 }
8229 /* Fold a unary expression of code CODE and type TYPE with operand
8230 OP0. Return the folded expression if folding is successful.
8231 Otherwise, return NULL_TREE. */
8233 tree
8235 {
8236 tree tem;
8237 tree arg0;
8245 {
8248 {
8249 /* Don't use STRIP_NOPS, because signedness of argument type
8250 matters. */
8252 }
8253 else
8254 {
8255 /* Strip any conversions that don't change the mode. This
8256 is safe for every expression, except for a comparison
8257 expression because its signedness is derived from its
8258 operands.
8260 Note that this is done as an internal manipulation within
8261 the constant folder, in order to find the simplest
8262 representation of the arguments so that their form can be
8263 studied. In any cases, the appropriate type conversions
8264 should be put back in the tree that will get out of the
8265 constant folder. */
8267 }
8268 }
8271 {
8278 {
8292 /* If this was a conversion, and all we did was to move into
8293 inside the COND_EXPR, bring it back out. But leave it if
8294 it is a conversion from integer to integer and the
8295 result precision is no wider than a word since such a
8296 conversion is cheap and may be optimized away by combine,
8297 while it couldn't if it were outside the COND_EXPR. Then return
8298 so we don't get into an infinite recursion loop taking the
8299 conversion out and then back in. */
8311 && (INTEGRAL_TYPE_P
8315 {
8324 }
8326 }
8328 {
8330 {
8334 }
8338 integer_one_node),
8340 integer_zero_node));
8341 }
8342 }
8345 {
8347 /* Re-association barriers around constants and other re-association
8348 barriers can be removed. */
8354 CASE_CONVERT:
8360 /* If we have (type) (a CMP b) and type is an integral type, return
8361 new expression involving the new type. */
8366 /* Handle cases of two conversions in a row. */
8368 {
8390 /* In addition to the cases of two conversions in a row
8391 handled below, if we are converting something to its own
8392 type via an object of identical or wider precision, neither
8393 conversion is needed. */
8400 /* Likewise, if the intermediate and initial types are either both
8401 float or both integer, we don't need the middle conversion if the
8402 former is wider than the latter and doesn't change the signedness
8403 (for integers). Avoid this if the final type is a pointer since
8404 then we sometimes need the middle conversion. Likewise if the
8405 final type has a precision not equal to the size of its mode. */
8414 && ! final_ptr
8418 /* If we have a sign-extension of a zero-extended value, we can
8419 replace that by a single zero-extension. */
8425 /* Two conversions in a row are not needed unless:
8426 - some conversion is floating-point (overstrict for now), or
8427 - some conversion is a vector (overstrict for now), or
8428 - the intermediate type is narrower than both initial and
8429 final, or
8430 - the intermediate type and innermost type differ in signedness,
8431 and the outermost type is wider than the intermediate, or
8432 - the initial type is a pointer type and the precisions of the
8433 intermediate and final types differ, or
8434 - the final type is a pointer type and the precisions of the
8435 initial and intermediate types differ. */
8449 }
8451 /* Handle (T *)&A.B.C for A being of type T and B and C
8452 living at offset zero. This occurs frequently in
8453 C++ upcasting and then accessing the base. */
8457 {
8459 tree offset;
8465 /* If the reference was to a (constant) zero offset, we can use
8466 the address of the base if it has the same base type
8467 as the result type. */
8473 }
8477 /* Detect assigning a bitfield. */
8479 && DECL_BIT_FIELD
8481 {
8482 /* Don't leave an assignment inside a conversion
8483 unless assigning a bitfield. */
8485 /* First do the assignment, then return converted constant. */
8491 }
8493 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8494 constants (if x has signed type, the sign bit cannot be set
8495 in c). This folds extension into the BIT_AND_EXPR.
8496 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8497 very likely don't have maximal range for their precision and this
8498 transformation effectively doesn't preserve non-maximal ranges. */
8502 {
8513 <= HOST_BITS_PER_WIDE_INT
8515 {
8522 #ifdef LOAD_EXTEND_OP
8524 && !flag_syntax_only
8527 {
8531 }
8532 #endif
8533 }
8535 {
8541 }
8542 }
8544 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8545 when one of the new casts will fold away. Conservatively we assume
8546 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8552 {
8560 }
8562 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8563 of the same precision, and X is an integer type not narrower than
8564 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8570 {
8576 }
8578 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8579 type of X and Y (integer types only). */
8584 {
8585 /* Be careful not to introduce new overflows. */
8586 tree mult_type;
8589 else
8593 {
8600 }
8601 }
8617 /* For integral conversions with the same precision or pointer
8618 conversions use a NOP_EXPR instead. */
8626 /* Strip inner integral conversions that do not change the precision. */
8650 /* Convert fabs((double)float) into (double)fabsf(float). */
8653 {
8659 targ0));
8660 }
8661 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8667 /* Strip sign ops from argument. */
8669 {
8674 }
8681 {
8687 }
8689 {
8694 }
8704 /* Convert ~ (-A) to A - 1. */
8709 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8718 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8733 /* Perform BIT_NOT_EXPR on each element individually. */
8735 {
8740 {
8742 {
8748 }
8749 else
8752 }
8755 }
8760 /* The argument to invert_truthvalue must have Boolean type. */
8764 /* Note that the operand of this must be an int
8765 and its values must be 0 or 1.
8766 ("true" is a fixed value perhaps depending on the language,
8767 but we don't handle values other than 1 correctly yet.) */
8782 {
8790 }
8792 {
8797 }
8799 {
8803 {
8812 }
8813 }
8825 {
8833 }
8835 {
8839 }
8841 {
8845 {
8854 }
8855 }
8861 }
8864 /* If the operation was a conversion do _not_ mark a resulting constant
8865 with TREE_OVERFLOW if the original constant was not. These conversions
8866 have implementation defined behavior and retaining the TREE_OVERFLOW
8867 flag here would confuse later passes such as VRP. */
8868 tree
8871 {
8880 }
8882 /* Fold a binary expression of code CODE and type TYPE with operands
8883 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8884 Return the folded expression if folding is successful. Otherwise,
8885 return NULL_TREE. */
8887 static tree
8889 {
8896 else
8899 /* MIN (MAX (a, b), b) == b. */
8904 /* MIN (MAX (b, a), b) == b. */
8910 /* MIN (a, MAX (a, b)) == a. */
8916 /* MIN (a, MAX (b, a)) == a. */
8923 }
8925 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8926 by changing CODE to reduce the magnitude of constants involved in
8927 ARG0 of the comparison.
8928 Returns a canonicalized comparison tree if a simplification was
8929 possible, otherwise returns NULL_TREE.
8930 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8931 valid if signed overflow is undefined. */
8933 static tree
8937 {
8943 /* Match A +- CST code arg1 and CST code arg1. We can change the
8944 first form only if overflow is undefined. */
8946 /* In principle pointers also have undefined overflow behavior,
8947 but that causes problems elsewhere. */
8955 /* Identify the constant in arg0 and its sign. */
8958 else
8962 /* Overflowed constants and zero will cause problems. */
8967 /* See if we can reduce the magnitude of the constant in
8968 arg0 by changing the comparison code. */
8970 {
8971 /* CST <= arg1 -> CST-1 < arg1. */
8974 /* -CST < arg1 -> -CST-1 <= arg1. */
8977 /* CST > arg1 -> CST-1 >= arg1. */
8980 /* -CST >= arg1 -> -CST-1 > arg1. */
8983 else
8985 /* arg1 code' CST' might be more canonical. */
8987 }
8988 else
8989 {
8990 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8994 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8998 /* A + CST <= arg1 -> A + CST-1 < arg1. */
9002 /* A - CST >= arg1 -> A - CST-1 > arg1. */
9006 else
9009 }
9011 /* Now build the constant reduced in magnitude. But not if that
9012 would produce one outside of its types range. */
9020 /* We cannot swap the comparison here as that would cause us to
9021 endlessly recurse. */
9029 /* If swapping might yield to a more canonical form, do so. */
9032 else
9034 }
9036 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
9037 overflow further. Try to decrease the magnitude of constants involved
9038 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
9039 and put sole constants at the second argument position.
9040 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
9042 static tree
9045 {
9046 tree t;
9051 /* Try canonicalization by simplifying arg0. */
9056 {
9060 }
9062 /* Try canonicalization by simplifying arg1 using the swapped
9063 comparison. */
9071 }
9073 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
9074 space. This is used to avoid issuing overflow warnings for
9075 expressions like &p->x which can not wrap. */
9077 static bool
9079 {
9090 {
9093 }
9096 else
9097 {
9100 }
9115 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
9116 array. */
9118 {
9119 HOST_WIDE_INT base_size;
9124 }
9127 }
9129 /* Subroutine of fold_binary. This routine performs all of the
9130 transformations that are common to the equality/inequality
9131 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9132 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9133 fold_binary should call fold_binary. Fold a comparison with
9134 tree code CODE and type TYPE with operands OP0 and OP1. Return
9135 the folded comparison or NULL_TREE. */
9137 static tree
9140 {
9153 /* If one arg is a real or integer constant, put it last. */
9157 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
9164 {
9168 tree lhs;
9175 /* If the constant operation overflowed this can be
9176 simplified as a comparison against INT_MAX/INT_MIN. */
9179 {
9183 /* Get the sign of the constant on the lhs if the
9184 operation were VARIABLE + CONST1. */
9188 /* The sign of the constant determines if we overflowed
9189 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9190 Canonicalize to the INT_MIN overflow by swapping the comparison
9191 if necessary. */
9195 /* We now can look at the canonicalized case
9196 VARIABLE + 1 CODE2 INT_MIN
9197 and decide on the result. */
9206 }
9211 {
9213 "when changing X +- C1 cmp C2 to "
9215 WARN_STRICT_OVERFLOW_COMPARISON);
9217 }
9218 }
9220 /* For comparisons of pointers we can decompose it to a compile time
9221 comparison of the base objects and the offsets into the object.
9222 This requires at least one operand being an ADDR_EXPR or a
9223 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9229 {
9236 /* Get base and offset for the access. Strip ADDR_EXPR for
9237 get_inner_reference, but put it back by stripping INDIRECT_REF
9238 off the base object if possible. indirect_baseN will be true
9239 if baseN is not an address but refers to the object itself. */
9242 {
9248 else
9250 }
9252 {
9255 }
9259 {
9265 else
9267 }
9269 {
9272 }
9274 /* If we have equivalent bases we might be able to simplify. */
9277 {
9278 /* We can fold this expression to a constant if the non-constant
9279 offset parts are equal. */
9287 {
9294 "occur when comparing P +- C1 with "
9296 WARN_STRICT_OVERFLOW_CONDITIONAL);
9299 {
9313 }
9314 }
9315 /* We can simplify the comparison to a comparison of the variable
9316 offset parts if the constant offset parts are equal.
9317 Be careful to use signed size type here because otherwise we
9318 mess with array offsets in the wrong way. This is possible
9319 because pointer arithmetic is restricted to retain within an
9320 object and overflow on pointer differences is undefined as of
9321 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9325 {
9326 tree signed_size_type_node;
9329 /* By converting to signed size type we cover middle-end pointer
9330 arithmetic which operates on unsigned pointer types of size
9331 type size and ARRAY_REF offsets which are properly sign or
9332 zero extended from their type in case it is narrower than
9333 size type. */
9336 else
9338 offset0);
9341 else
9343 offset1);
9350 "occur when comparing P +- C1 with "
9352 WARN_STRICT_OVERFLOW_COMPARISON);
9355 }
9356 }
9357 /* For non-equal bases we can simplify if they are addresses
9358 of local binding decls or constants. */
9360 /* We know that !operand_equal_p (base0, base1, 0)
9361 because the if condition was false. But make
9362 sure two decls are not the same. */
9376 {
9383 }
9384 /* For equal offsets we can simplify to a comparison of the
9385 base addresses. */
9387 && (indirect_base0
9389 && (indirect_base1
9394 {
9400 }
9401 }
9403 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9404 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9405 the resulting offset is smaller in absolute value than the
9406 original one. */
9414 {
9419 tree cst;
9421 "occur when combining constants around "
9424 /* Put the constant on the side where it doesn't overflow and is
9425 of lower absolute value than before. */
9431 {
9434 variable1,
9438 }
9445 {
9450 variable2);
9451 }
9452 }
9454 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9455 signed arithmetic case. That form is created by the compiler
9456 often enough for folding it to be of value. One example is in
9457 computing loop trip counts after Operator Strength Reduction. */
9463 {
9472 "eliminating multiplication in comparison "
9474 WARN_STRICT_OVERFLOW_COMPARISON);
9476 /* If const1 is negative we swap the sense of the comparison. */
9481 }
9488 {
9496 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9502 /* (-a) CMP (-b) -> b CMP a */
9509 {
9510 REAL_VALUE_TYPE cst;
9513 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9520 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9521 /* a CMP (-0) -> a CMP 0 */
9526 /* x != NaN is always true, other ops are always false. */
9529 {
9532 }
9534 /* Fold comparisons against infinity. */
9537 {
9541 }
9542 }
9544 /* If this is a comparison of a real constant with a PLUS_EXPR
9545 or a MINUS_EXPR of a real constant, we can convert it into a
9546 comparison with a revised real constant as long as no overflow
9547 occurs when unsafe_math_optimizations are enabled. */
9559 /* Likewise, we can simplify a comparison of a real constant with
9560 a MINUS_EXPR whose first operand is also a real constant, i.e.
9561 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9562 floating-point types only if -fassociative-math is set. */
9573 /* Fold comparisons against built-in math functions. */
9575 && flag_unsafe_math_optimizations
9577 {
9581 {
9585 }
9586 }
9587 }
9591 {
9592 /* If we are widening one operand of an integer comparison,
9593 see if the other operand is similarly being widened. Perhaps we
9594 can do the comparison in the narrower type. */
9599 /* Or if we are changing signedness. */
9603 }
9605 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9606 constant, we can simplify it. */
9611 {
9615 }
9617 /* Simplify comparison of something with itself. (For IEEE
9618 floating-point, we can only do some of these simplifications.) */
9620 {
9622 {
9637 /* For NE, we can only do this simplification if integer
9638 or we don't honor IEEE floating point NaNs. */
9642 /* ... fall through ... */
9648 }
9649 }
9651 /* If we are comparing an expression that just has comparisons
9652 of two integer values, arithmetic expressions of those comparisons,
9653 and constants, we can simplify it. There are only three cases
9654 to check: the two values can either be equal, the first can be
9655 greater, or the second can be greater. Fold the expression for
9656 those three values. Since each value must be 0 or 1, we have
9657 eight possibilities, each of which corresponds to the constant 0
9658 or 1 or one of the six possible comparisons.
9660 This handles common cases like (a > b) == 0 but also handles
9661 expressions like ((x > y) - (y > x)) > 0, which supposedly
9662 occur in macroized code. */
9665 {
9670 /* Don't handle degenerate cases here; they should already
9671 have been handled anyway. */
9680 {
9684 /* We can't just pass T to eval_subst in case cval1 or cval2
9685 was the same as ARG1. */
9687 tree high_result
9691 arg1);
9692 tree equal_result
9696 arg1);
9697 tree low_result
9701 arg1);
9703 /* All three of these results should be 0 or 1. Confirm they are.
9704 Then use those values to select the proper code to use. */
9709 {
9710 /* Make a 3-bit mask with the high-order bit being the
9711 value for `>', the next for '=', and the low for '<'. */
9715 {
9717 /* Always false. */
9738 /* Always true. */
9740 }
9743 {
9747 }
9749 }
9750 }
9751 }
9753 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9754 into a single range test. */
9762 {
9766 }
9768 /* Fold ~X op ~Y as Y op X. */
9771 {
9777 }
9779 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9782 {
9788 }
9791 }
9794 /* Subroutine of fold_binary. Optimize complex multiplications of the
9795 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9796 argument EXPR represents the expression "z" of type TYPE. */
9798 static tree
9800 {
9805 {
9808 }
9810 {
9813 }
9814 else
9815 {
9819 }
9828 }
9831 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9832 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9833 guarantees that P and N have the same least significant log2(M) bits.
9834 N is not otherwise constrained. In particular, N is not normalized to
9835 0 <= N < M as is common. In general, the precise value of P is unknown.
9836 M is chosen as large as possible such that constant N can be determined.
9838 Returns M and sets *RESIDUE to N.
9840 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9841 account. This is not always possible due to PR 35705.
9842 */
9844 static unsigned HOST_WIDE_INT
9847 {
9854 {
9857 {
9859 tree offset;
9867 {
9870 else
9871 /* We don't handle more complicated offset expressions. */
9873 }
9874 }
9879 }
9881 {
9889 allow_func_align);
9895 {
9898 }
9900 {
9903 {
9906 /* Compute the greatest power-of-2 divisor of op1. */
9910 /* If align is non-zero and less than *modulus, replace
9911 *modulus with align., If align is 0, then either op1 is 0
9912 or the greatest power-of-2 divisor of op1 doesn't fit in an
9913 unsigned HOST_WIDE_INT. In either case, no additional
9914 constraint is imposed. */
9919 }
9920 }
9921 }
9923 /* If we get here, we were unable to determine anything useful about the
9924 expression. */
9926 }
9929 /* Fold a binary expression of code CODE and type TYPE with operands
9930 OP0 and OP1. LOC is the location of the resulting expression.
9931 Return the folded expression if folding is successful. Otherwise,
9932 return NULL_TREE. */
9934 tree
9937 {
9951 /* Strip any conversions that don't change the mode. This is
9952 safe for every expression, except for a comparison expression
9953 because its signedness is derived from its operands. So, in
9954 the latter case, only strip conversions that don't change the
9955 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9956 preserved.
9958 Note that this is done as an internal manipulation within the
9959 constant folder, in order to find the simplest representation
9960 of the arguments so that their form can be studied. In any
9961 cases, the appropriate type conversions should be put back in
9962 the tree that will get out of the constant folder. */
9965 {
9968 }
9969 else
9970 {
9973 }
9975 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9976 constant but we can't do arithmetic on them. */
9983 {
9985 {
9986 /* Make sure type and arg0 have the same saturating flag. */
9990 }
9993 else
9997 {
10001 }
10002 }
10004 /* If this is a commutative operation, and ARG0 is a constant, move it
10005 to ARG1 to reduce the number of tests below. */
10010 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10012 First check for cases where an arithmetic operation is applied to a
10013 compound, conditional, or comparison operation. Push the arithmetic
10014 operation inside the compound or conditional to see if any folding
10015 can then be done. Convert comparison to conditional for this purpose.
10016 The also optimizes non-constant cases that used to be done in
10017 expand_expr.
10019 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10020 one of the operands is a comparison and the other is a comparison, a
10021 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10022 code below would make the expression more complex. Change it to a
10023 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10024 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10036 {
10040 boolean_type_node,
10048 }
10052 {
10054 {
10061 }
10064 {
10071 }
10074 {
10080 }
10083 {
10089 }
10090 }
10093 {
10095 /* 0 +p index -> (type)index */
10099 /* PTR +p 0 -> PTR */
10103 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10109 arg1),
10111 arg0)));
10113 /* index +p PTR -> PTR +p index */
10120 /* (PTR +p B) +p A -> PTR +p (B + A) */
10122 {
10123 tree inner;
10132 }
10134 /* PTR_CST +p CST -> CST1 */
10139 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10140 of the array. Loop optimizer sometimes produce this type of
10141 expressions. */
10143 {
10148 }
10153 /* A + (-B) -> A - B */
10159 /* (-A) + B -> B - A */
10168 {
10169 /* Convert ~A + 1 to -A. */
10176 /* ~X + X is -1. */
10179 {
10184 {
10187 }
10188 }
10190 /* X + ~X is -1. */
10193 {
10198 {
10201 }
10202 }
10204 /* X + (X / CST) * -CST is X % CST. */
10209 {
10218 cst0));
10219 }
10220 }
10222 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
10223 same or one. Make sure type is not saturating.
10224 fold_plusminus_mult_expr will re-associate. */
10229 {
10233 }
10236 {
10240 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10241 with a constant, and the two constants have no bits in common,
10242 we should treat this as a BIT_IOR_EXPR since this may produce more
10243 simplifications. */
10251 {
10254 }
10256 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10257 (plus (plus (mult) (mult)) (foo)) so that we can
10258 take advantage of the factoring cases below. */
10265 {
10271 else
10284 parg0),
10286 marg)),
10290 return
10296 parg1)));
10297 }
10298 }
10299 else
10300 {
10301 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10305 /* Likewise if the operands are reversed. */
10309 /* Convert X + -C into X - C. */
10312 {
10318 }
10320 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10321 to __complex__ ( x, y ). This is not the same for SNaNs or
10322 if signed zeros are involved. */
10326 {
10333 {
10337 {
10343 }
10345 {
10351 }
10352 }
10353 }
10361 /* Convert x+x into x*2.0. */
10367 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10368 We associate floats only if the user has specified
10369 -fassociative-math. */
10373 {
10378 {
10379 tree tree0;
10382 }
10383 }
10384 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10385 We associate floats only if the user has specified
10386 -fassociative-math. */
10390 {
10395 {
10396 tree tree0;
10399 }
10400 }
10401 }
10403 bit_rotate:
10404 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10405 is a rotate of A by C1 bits. */
10406 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10407 is a rotate of A by B bits. */
10408 {
10410 tree rtype;
10419 /* Only create rotates in complete modes. Other cases are not
10420 expanded properly. */
10422 {
10438 {
10442 code0 == LSHIFT_EXPR
10446 }
10448 {
10456 TYPE_PRECISION
10460 return
10463 ? LROTATE_EXPR
10467 }
10469 {
10477 TYPE_PRECISION
10481 return fold_convert_loc
10484 ? LROTATE_EXPR
10488 }
10489 }
10490 }
10492 associate:
10493 /* In most languages, can't associate operations on floats through
10494 parentheses. Rather than remember where the parentheses were, we
10495 don't associate floats at all, unless the user has specified
10496 -fassociative-math.
10497 And, we need to make sure type is not saturating. */
10501 {
10506 /* Split both trees into variables, constants, and literals. Then
10507 associate each group together, the constants with literals,
10508 then the result with variables. This increases the chances of
10509 literals being recombined later and of generating relocatable
10510 expressions for the sum of a constant and literal. */
10515 /* With undefined overflow we can only associate constants
10516 with one variable. */
10520 {
10528 /* The only case we can still associate with two variables
10529 is if they are the same, modulo negation. */
10532 }
10534 /* Only do something if we found more than two objects. Otherwise,
10535 nothing has changed and we risk infinite recursion. */
10541 {
10542 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10551 /* Preserve the MINUS_EXPR if the negative part of the literal is
10552 greater than the positive part. Otherwise, the multiplicative
10553 folding code (i.e extract_muldiv) may be fooled in case
10554 unsigned constants are subtracted, like in the following
10555 example: ((X*2 + 4) - 8U)/2. */
10557 {
10561 {
10565 }
10566 else
10567 {
10571 }
10572 }
10574 {
10576 return
10580 else
10581 {
10584 return
10588 }
10589 }
10592 return
10595 }
10596 }
10601 /* Pointer simplifications for subtraction, simple reassociations. */
10603 {
10604 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10607 {
10617 }
10618 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10620 {
10627 }
10628 }
10629 /* A - (-B) -> A + B */
10634 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10645 /* Convert -A - 1 to ~A. */
10654 /* Convert -1 - A to ~A. */
10660 /* X - (X / CST) * CST is X % CST. */
10668 return
10674 {
10680 /* Fold A - (A & B) into ~B & A. */
10683 {
10685 {
10692 }
10694 {
10701 }
10702 }
10704 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10705 any power of 2 minus 1. */
10710 {
10716 {
10720 }
10721 }
10722 }
10724 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10728 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10729 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10730 (-ARG1 + ARG0) reduces to -ARG1. */
10734 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10735 __complex__ ( x, -y ). This is not the same for SNaNs or if
10736 signed zeros are involved. */
10740 {
10747 {
10751 {
10753 arg1r ? arg1r
10758 }
10760 {
10764 arg1i ? arg1i
10767 }
10768 }
10769 }
10771 /* Fold &x - &x. This can happen from &x.foo - &x.
10772 This is unsafe for certain floats even in non-IEEE formats.
10773 In IEEE, it is unsafe because it does wrong for NaNs.
10774 Also note that operand_equal_p is always false if an operand
10775 is volatile. */
10781 /* A - B -> A + (-B) if B is easily negatable. */
10784 /* Avoid this transformation if B is a positive REAL_CST. */
10793 /* Try folding difference of addresses. */
10794 {
10795 HOST_WIDE_INT diff;
10801 }
10803 /* Fold &a[i] - &a[j] to i-j. */
10808 {
10813 {
10821 }
10822 }
10825 && flag_unsafe_math_optimizations
10831 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10832 same or one. Make sure type is not saturating.
10833 fold_plusminus_mult_expr will re-associate. */
10838 {
10842 }
10847 /* (-A) * (-B) -> A * B */
10862 {
10867 /* Transform x * -1 into -x. Make sure to do the negation
10868 on the original operand with conversions not stripped
10869 because we can only strip non-sign-changing conversions. */
10872 /* Transform x * -C into -x * C if x is easily negatable. */
10881 tem);
10883 /* (a * (1 << b)) is (a << b) */
10893 /* (A + A) * C -> A * 2 * C */
10909 {
10912 "occur when simplifying "
10914 WARN_STRICT_OVERFLOW_MISC);
10916 }
10918 /* Optimize z * conj(z) for integer complex numbers. */
10925 }
10926 else
10927 {
10928 /* Maybe fold x * 0 to 0. The expressions aren't the same
10929 when x is NaN, since x * 0 is also NaN. Nor are they the
10930 same in modes with signed zeros, since multiplying a
10931 negative value by 0 gives -0, not +0. */
10936 /* In IEEE floating point, x*1 is not equivalent to x for snans.
10937 Likewise for complex arithmetic with signed zeros. */
10944 /* Transform x * -1.0 into -x. */
10951 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10952 the result for floating point types due to rounding so it is applied
10953 only if -fassociative-math was specify. */
10958 {
10964 }
10966 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10968 {
10971 {
10974 }
10975 }
10977 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10978 This is not the same for NaNs or if signed zeros are
10979 involved. */
10985 {
10988 return
10994 return
10999 }
11001 /* Optimize z * conj(z) for floating point complex numbers.
11002 Guarded by flag_unsafe_math_optimizations as non-finite
11003 imaginary components don't produce scalar results. */
11014 {
11018 /* Optimizations of root(...)*root(...). */
11020 {
11025 /* Optimize sqrt(x)*sqrt(x) as x. */
11031 /* Optimize root(x)*root(y) as root(x*y). */
11035 }
11037 /* Optimize expN(x)*expN(y) as expN(x+y). */
11039 {
11045 }
11047 /* Optimizations of pow(...)*pow(...). */
11051 {
11057 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11059 {
11064 }
11066 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11068 {
11073 }
11074 }
11076 /* Optimize tan(x)*cos(x) as sin(x). */
11085 {
11091 }
11093 /* Optimize x*pow(x,c) as pow(x,c+1). */
11097 {
11103 {
11105 REAL_VALUE_TYPE c;
11106 tree arg;
11112 }
11113 }
11115 /* Optimize pow(x,c)*x as pow(x,c+1). */
11119 {
11125 {
11127 REAL_VALUE_TYPE c;
11128 tree arg;
11134 }
11135 }
11137 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
11140 {
11144 {
11147 }
11148 }
11149 }
11150 }
11154 bit_ior:
11162 /* ~X | X is -1. */
11165 {
11169 }
11171 /* X | ~X is -1. */
11174 {
11178 }
11180 /* Canonicalize (X & C1) | C2. */
11184 {
11192 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11198 {
11202 }
11203 else
11204 {
11208 }
11210 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11215 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11216 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11217 mode which allows further optimizations. */
11227 {
11228 unsigned HOST_WIDE_INT mask
11232 {
11236 }
11237 }
11244 arg1);
11245 }
11247 /* (X & Y) | Y is (X, Y). */
11251 /* (X & Y) | X is (Y, X). */
11256 /* X | (X & Y) is (Y, X). */
11261 /* X | (Y & X) is (Y, X). */
11271 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11273 This results in more efficient code for machines without a NAND
11274 instruction. Combine will canonicalize to the first form
11275 which will allow use of NAND instructions provided by the
11276 backend if they exist. */
11279 {
11280 return
11287 }
11289 /* See if this can be simplified into a rotate first. If that
11290 is unsuccessful continue in the association code. */
11301 /* ~X ^ X is -1. */
11304 {
11308 }
11310 /* X ^ ~X is -1. */
11313 {
11317 }
11319 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11320 with a constant, and the two constants have no bits in common,
11321 we should treat this as a BIT_IOR_EXPR since this may produce more
11322 simplifications. */
11330 {
11333 }
11335 /* (X | Y) ^ X -> Y & ~ X*/
11338 {
11341 arg1);
11346 }
11348 /* (Y | X) ^ X -> Y & ~ X*/
11351 {
11354 arg1);
11359 }
11361 /* X ^ (X | Y) -> Y & ~ X*/
11364 {
11367 arg0);
11372 }
11374 /* X ^ (Y | X) -> Y & ~ X*/
11377 {
11380 arg0);
11385 }
11387 /* Convert ~X ^ ~Y to X ^ Y. */
11396 /* Convert ~X ^ C to X ^ ~C. */
11404 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11411 /* Fold (X & Y) ^ Y as ~X & Y. */
11414 {
11419 }
11420 /* Fold (X & Y) ^ X as ~Y & X. */
11424 {
11429 }
11430 /* Fold X ^ (X & Y) as X & ~Y. */
11433 {
11438 }
11439 /* Fold X ^ (Y & X) as ~Y & X. */
11443 {
11448 }
11450 /* See if this can be simplified into a rotate first. If that
11451 is unsuccessful continue in the association code. */
11462 /* ~X & X is always zero. */
11467 /* X & ~X is always zero. */
11472 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11476 {
11482 return
11486 }
11488 /* (X | Y) & Y is (X, Y). */
11492 /* (X | Y) & X is (Y, X). */
11497 /* X & (X | Y) is (Y, X). */
11502 /* X & (Y | X) is (Y, X). */
11508 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11512 {
11518 }
11519 /* Fold ~X & 1 as (X & 1) == 0. */
11522 {
11528 }
11530 /* Fold (X ^ Y) & Y as ~X & Y. */
11533 {
11538 }
11539 /* Fold (X ^ Y) & X as ~Y & X. */
11543 {
11548 }
11549 /* Fold X & (X ^ Y) as X & ~Y. */
11552 {
11557 }
11558 /* Fold X & (Y ^ X) as ~Y & X. */
11562 {
11567 }
11572 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11575 {
11576 unsigned int prec
11582 return
11584 }
11586 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11588 This results in more efficient code for machines without a NOR
11589 instruction. Combine will canonicalize to the first form
11590 which will allow use of NOR instructions provided by the
11591 backend if they exist. */
11594 {
11601 }
11603 /* If arg0 is derived from the address of an object or function, we may
11604 be able to fold this expression using the object or function's
11605 alignment. */
11607 {
11614 /* This works because modulus is a power of 2. If this weren't the
11615 case, we'd have to replace it by its greatest power-of-2
11616 divisor: modulus & -modulus. */
11619 }
11621 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11622 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11623 if the new mask might be further optimized. */
11632 {
11634 unsigned HOST_WIDE_INT mask
11644 {
11647 /* See if more bits can be proven as zero because of
11648 zero extension. */
11651 {
11656 {
11658 /* See if we can shorten the right shift. */
11661 }
11662 }
11666 /* For arithmetic shift if sign bit could be set, zerobits
11667 can contain actually sign bits, so no transformation is
11668 possible, unless MASK masks them all away. In that
11669 case the shift needs to be converted into logical shift. */
11672 {
11675 else
11677 }
11678 }
11680 /* ((X << 16) & 0xff00) is (X, 0). */
11687 {
11690 /* Only do the transformation if NEWMASK is some integer
11691 mode's mask. */
11698 {
11699 tree newmaskt;
11702 {
11708 }
11709 else
11714 }
11715 }
11716 }
11721 /* Don't touch a floating-point divide by zero unless the mode
11722 of the constant can represent infinity. */
11728 /* Optimize A / A to 1.0 if we don't care about
11729 NaNs or Infinities. Skip the transformation
11730 for non-real operands. */
11735 {
11739 }
11741 /* The complex version of the above A / A optimization. */
11744 {
11748 {
11750 /* omit_two_operands will call fold_convert for us. */
11752 }
11753 }
11755 /* (-A) / (-B) -> A / B */
11765 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11770 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11776 /* If ARG1 is a constant, we can convert this to a multiply by the
11777 reciprocal. This does not have the same rounding properties,
11778 so only do this if -freciprocal-math. We can actually
11779 always safely do it if ARG1 is a power of two, but it's hard to
11780 tell if it is or not in a portable manner. */
11782 {
11787 /* Find the reciprocal if optimizing and the result is exact. */
11789 {
11790 REAL_VALUE_TYPE r;
11793 {
11797 }
11798 }
11799 }
11800 /* Convert A/B/C to A/(B*C). */
11807 /* Convert A/(B/C) to (A/B)*C. */
11815 /* Convert C1/(X*C2) into (C1/C2)/X. */
11820 {
11826 }
11829 {
11833 /* Optimize sin(x)/cos(x) as tan(x). */
11839 {
11844 }
11846 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11852 {
11856 {
11861 }
11862 }
11864 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11865 NaNs or Infinities. */
11869 {
11876 {
11881 }
11882 }
11884 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11885 NaNs or Infinities. */
11889 {
11896 {
11900 {
11904 tmp);
11905 }
11906 }
11907 }
11909 /* Optimize pow(x,c)/x as pow(x,c-1). */
11913 {
11919 {
11921 REAL_VALUE_TYPE c;
11922 tree arg;
11928 }
11929 }
11931 /* Optimize a/root(b/c) into a*root(c/b). */
11933 {
11937 {
11946 }
11947 }
11949 /* Optimize x/expN(y) into x*expN(-y). */
11951 {
11958 }
11960 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11964 {
11972 }
11973 }
11978 /* Simplify A / (B << N) where A and B are positive and B is
11979 a power of 2, to A >> (N + log2(B)). */
11984 {
11987 {
11994 WARN_STRICT_OVERFLOW_MISC);
12000 }
12001 }
12003 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
12004 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12010 /* Fall thru */
12019 /* X / -1 is -X. */
12026 /* Convert -A / -B to A / B when the type is signed and overflow is
12027 undefined. */
12031 {
12034 "when distributing negation across "
12036 WARN_STRICT_OVERFLOW_MISC);
12042 }
12046 {
12049 "when distributing negation across "
12051 WARN_STRICT_OVERFLOW_MISC);
12057 }
12059 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12060 operation, EXACT_DIV_EXPR.
12062 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12063 At one time others generated faster code, it's not clear if they do
12064 after the last round to changes to the DIV code in expmed.c. */
12073 {
12077 WARN_STRICT_OVERFLOW_MISC);
12079 }
12087 /* X % 1 is always zero, but be sure to preserve any side
12088 effects in X. */
12092 /* X % 0, return X % 0 unchanged so that we can get the
12093 proper warnings and errors. */
12097 /* 0 % X is always zero, but be sure to preserve any side
12098 effects in X. Place this after checking for X == 0. */
12102 /* X % -1 is zero. */
12109 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12110 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12115 {
12117 /* Also optimize A % (C << N) where C is a power of 2,
12118 to A & ((C << N) - 1). */
12123 {
12128 "occur when simplifying "
12130 WARN_STRICT_OVERFLOW_MISC);
12134 }
12135 }
12137 /* X % -C is the same as X % C. */
12144 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12151 /* X % -Y is the same as X % Y. */
12163 {
12167 WARN_STRICT_OVERFLOW_MISC);
12169 }
12180 /* Optimize -1 >> x for arithmetic right shifts. */
12184 /* ... fall through ... */
12187 shift:
12193 /* Since negative shift count is not well-defined,
12194 don't try to compute it in the compiler. */
12198 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12203 {
12207 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12208 being well defined. */
12210 {
12216 else
12218 }
12222 }
12224 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12225 into x & ((unsigned)-1 >> c) for unsigned types. */
12233 {
12236 tree lshift;
12237 tree arg00;
12240 {
12247 }
12248 }
12250 /* Rewrite an LROTATE_EXPR by a constant into an
12251 RROTATE_EXPR by a new constant. */
12253 {
12258 }
12260 /* If we have a rotate of a bit operation with the rotate count and
12261 the second operand of the bit operation both constant,
12262 permute the two operations. */
12274 /* Two consecutive rotates adding up to the precision of the
12275 type can be ignored. */
12286 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12287 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12288 if the latter can be further optimized. */
12293 {
12297 arg1);
12301 arg1);
12305 }
12333 /* Note that the operands of this must be ints
12334 and their values must be 0 or 1.
12335 ("true" is a fixed value perhaps depending on the language.) */
12336 /* If first arg is constant zero, return it. */
12340 /* If either arg is constant true, drop it. */
12344 /* Preserve sequence points. */
12347 /* If second arg is constant zero, result is zero, but first arg
12348 must be evaluated. */
12351 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12352 case will be handled here. */
12356 /* !X && X is always false. */
12360 /* X && !X is always false. */
12365 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12366 means A >= Y && A != MAX, but in this case we know that
12367 A < X <= MAX. */
12371 {
12379 }
12381 truth_andor:
12382 /* We only do these simplifications if we are optimizing. */
12386 /* Check for things like (A || B) && (A || C). We can convert this
12387 to A || (B && C). Note that either operator can be any of the four
12388 truth and/or operations and the transformation will still be
12389 valid. Also note that we only care about order for the
12390 ANDIF and ORIF operators. If B contains side effects, this
12391 might change the truth-value of A. */
12398 {
12418 /* This case if tricky because we must either have commutative
12419 operators or else A10 must not have side-effects. */
12425 a01);
12426 }
12428 /* See if we can build a range comparison. */
12432 /* Check for the possibility of merging component references. If our
12433 lhs is another similar operation, try to merge its rhs with our
12434 rhs. Then try to merge our lhs and rhs. */
12446 /* Note that the operands of this must be ints
12447 and their values must be 0 or true.
12448 ("true" is a fixed value perhaps depending on the language.) */
12449 /* If first arg is constant true, return it. */
12453 /* If either arg is constant zero, drop it. */
12457 /* Preserve sequence points. */
12460 /* If second arg is constant true, result is true, but we must
12461 evaluate first arg. */
12464 /* Likewise for first arg, but note this only occurs here for
12465 TRUTH_OR_EXPR. */
12469 /* !X || X is always true. */
12473 /* X || !X is always true. */
12481 /* If the second arg is constant zero, drop it. */
12484 /* If the second arg is constant true, this is a logical inversion. */
12486 {
12487 /* Only call invert_truthvalue if operand is a truth value. */
12490 else
12493 }
12494 /* Identical arguments cancel to zero. */
12498 /* !X ^ X is always true. */
12503 /* X ^ !X is always true. */
12516 /* bool_var != 0 becomes bool_var. */
12521 /* bool_var == 1 becomes bool_var. */
12526 /* bool_var != 1 becomes !bool_var. */
12532 /* bool_var == 0 becomes !bool_var. */
12538 /* If this is an equality comparison of the address of two non-weak,
12539 unaliased symbols neither of which are extern (since we do not
12540 have access to attributes for externs), then we know the result. */
12553 {
12554 /* We know that we're looking at the address of two
12555 non-weak, unaliased, static _DECL nodes.
12557 It is both wasteful and incorrect to call operand_equal_p
12558 to compare the two ADDR_EXPR nodes. It is wasteful in that
12559 all we need to do is test pointer equality for the arguments
12560 to the two ADDR_EXPR nodes. It is incorrect to use
12561 operand_equal_p as that function is NOT equivalent to a
12562 C equality test. It can in fact return false for two
12563 objects which would test as equal using the C equality
12564 operator. */
12568 type);
12569 }
12571 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12572 a MINUS_EXPR of a constant, we can convert it into a comparison with
12573 a revised constant as long as no overflow occurs. */
12581 arg1),
12586 /* Similarly for a NEGATE_EXPR. */
12594 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12602 arg1),
12605 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12612 {
12616 val,
12620 }
12622 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12627 {
12629 code == NE_EXPR
12632 }
12634 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12635 for !=. Don't do this for ordered comparisons due to overflow. */
12641 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12646 /* If this is an EQ or NE comparison with zero and ARG0 is
12647 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12648 two operations, but the latter can be done in one less insn
12649 on machines that have only two-operand insns or on which a
12650 constant cannot be the first operand. */
12653 {
12658 {
12665 arg1);
12666 }
12669 {
12676 arg1);
12677 }
12678 }
12680 /* If this is an NE or EQ comparison of zero against the result of a
12681 signed MOD operation whose second operand is a power of 2, make
12682 the MOD operation unsigned since it is simpler and equivalent. */
12690 {
12700 }
12702 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12703 C1 is a valid shift constant, and C2 is a power of two, i.e.
12704 a single bit. */
12708 == INTEGER_CST
12711 {
12716 /* Check for a valid shift count. */
12719 {
12723 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12724 can be rewritten as (X & (C2 << C1)) != 0. */
12726 {
12730 }
12731 /* Otherwise, for signed (arithmetic) shifts,
12732 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12733 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12737 /* Otherwise, of unsigned (logical) shifts,
12738 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12739 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12740 else
12744 arg000);
12745 }
12746 }
12748 /* If this is an NE comparison of zero with an AND of one, remove the
12749 comparison since the AND will give the correct value. */
12756 /* If we have (A & C) == C where C is a power of 2, convert this into
12757 (A & C) != 0. Similarly for NE_EXPR. */
12763 integer_zero_node));
12765 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12766 bit, then fold the expression into A < 0 or A >= 0. */
12771 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12772 Similarly for NE_EXPR. */
12776 {
12785 }
12787 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12788 Similarly for NE_EXPR. */
12792 {
12799 }
12801 /* If this is a comparison of a field, we may be able to simplify it. */
12804 /* Handle the constant case even without -O
12805 to make sure the warnings are given. */
12807 {
12811 }
12813 /* Optimize comparisons of strlen vs zero to a compare of the
12814 first character of the string vs zero. To wit,
12815 strlen(ptr) == 0 => *ptr == 0
12816 strlen(ptr) != 0 => *ptr != 0
12817 Other cases should reduce to one of these two (or a constant)
12818 due to the return value of strlen being unsigned. */
12821 {
12829 {
12834 }
12835 }
12837 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12838 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12842 {
12849 {
12851 {
12854 }
12857 }
12858 }
12860 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12866 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12871 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12878 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12886 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12887 (X & C) == 0 when C is a single bit. */
12892 {
12898 }
12900 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12901 constant C is a power of two, i.e. a single bit. */
12908 {
12912 }
12914 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12915 when is C is a power of two, i.e. a single bit. */
12922 {
12928 }
12932 {
12935 }
12937 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12944 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12947 {
12960 arg01),
12969 arg01),
12978 arg00),
12987 arg00),
12989 }
12993 {
13000 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
13001 operand_equal_p guarantees no side-effects so we don't need
13002 to use omit_one_operand on Z. */
13012 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13020 arg10);
13021 }
13023 /* Attempt to simplify equality/inequality comparisons of complex
13024 values. Only lower the comparison if the result is known or
13025 can be simplified to a single scalar comparison. */
13030 {
13035 {
13038 }
13039 else
13040 {
13043 }
13046 {
13049 }
13050 else
13051 {
13054 }
13058 {
13060 {
13065 }
13066 else
13067 {
13072 }
13073 }
13077 {
13079 {
13084 }
13085 else
13086 {
13091 }
13092 }
13093 }
13105 /* Transform comparisons of the form X +- C CMP X. */
13112 {
13119 else
13122 /* (X - c) > X becomes false. */
13126 {
13130 "occur when assuming that (X - c) > X "
13132 WARN_STRICT_OVERFLOW_ALL);
13134 }
13136 /* Likewise (X + c) < X becomes false. */
13140 {
13144 "occur when assuming that "
13146 WARN_STRICT_OVERFLOW_ALL);
13148 }
13150 /* Convert (X - c) <= X to true. */
13155 {
13159 "occur when assuming that "
13161 WARN_STRICT_OVERFLOW_ALL);
13163 }
13165 /* Convert (X + c) >= X to true. */
13170 {
13174 "occur when assuming that "
13176 WARN_STRICT_OVERFLOW_ALL);
13178 }
13181 {
13182 /* Convert X + c > X and X - c < X to true for integers. */
13186 {
13189 "not occur when assuming that "
13191 WARN_STRICT_OVERFLOW_ALL);
13193 }
13198 {
13201 "not occur when assuming that "
13203 WARN_STRICT_OVERFLOW_ALL);
13205 }
13207 /* Convert X + c <= X and X - c >= X to false for integers. */
13211 {
13214 "not occur when assuming that "
13216 WARN_STRICT_OVERFLOW_ALL);
13218 }
13223 {
13226 "not occur when assuming that "
13228 WARN_STRICT_OVERFLOW_ALL);
13230 }
13231 }
13232 }
13234 /* Comparisons with the highest or lowest possible integer of
13235 the specified precision will have known values. */
13236 {
13243 {
13244 HOST_WIDE_INT signed_max_hi;
13249 {
13256 {
13260 }
13261 else
13262 {
13266 }
13267 }
13268 else
13269 {
13278 {
13281 }
13282 else
13283 {
13286 }
13287 }
13292 {
13305 /* The GE_EXPR and LT_EXPR cases above are not normally
13306 reached because of previous transformations. */
13310 }
13312 == max_hi
13315 {
13322 arg1);
13328 arg0),
13329 arg1);
13332 }
13334 == min_hi
13337 {
13352 }
13354 == min_hi
13357 {
13363 arg1);
13368 arg0),
13369 arg1);
13372 }
13377 /* We will flip the signedness of the comparison operator
13378 associated with the mode of arg1, so the sign bit is
13379 specified by this mode. Check that arg1 is the signed
13380 max associated with this sign bit. */
13382 /* signed_type does not work on pointer types. */
13384 {
13385 /* The following case also applies to X < signed_max+1
13386 and X >= signed_max+1 because previous transformations. */
13388 {
13389 tree st;
13395 }
13396 }
13397 }
13398 }
13400 /* If we are comparing an ABS_EXPR with a constant, we can
13401 convert all the cases into explicit comparisons, but they may
13402 well not be faster than doing the ABS and one comparison.
13403 But ABS (X) <= C is a range comparison, which becomes a subtraction
13404 and a comparison, and is probably faster. */
13418 /* Convert ABS_EXPR<x> >= 0 to true. */
13425 {
13428 "when simplifying comparison of "
13430 WARN_STRICT_OVERFLOW_CONDITIONAL);
13432 }
13434 /* Convert ABS_EXPR<x> < 0 to false. */
13439 {
13442 "when simplifying comparison of "
13444 WARN_STRICT_OVERFLOW_CONDITIONAL);
13446 }
13448 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13449 and similarly for >= into !=. */
13454 {
13460 }
13467 {
13476 }
13489 {
13493 }
13495 /* If the first operand is NaN, the result is constant. */
13499 {
13501 ? integer_zero_node
13504 }
13506 /* If the second operand is NaN, the result is constant. */
13510 {
13512 ? integer_zero_node
13515 }
13517 /* Simplify unordered comparison of something with itself. */
13523 && !flag_trapping_math
13527 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13528 {
13540 }
13545 /* When pedantic, a compound expression can be neither an lvalue
13546 nor an integer constant expression. */
13549 /* Don't let (0, 0) be null pointer constant. */
13563 /* An ASSERT_EXPR should never be passed to fold_binary. */
13569 fold_binary_exit:
13572 }
13574 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13575 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13576 of GOTO_EXPR. */
13578 static tree
13580 {
13582 {
13589 /* ... fall through ... */
13593 }
13594 }
13596 /* Return whether the sub-tree ST contains a label which is accessible from
13597 outside the sub-tree. */
13599 static bool
13601 {
13602 return
13604 }
13606 /* Fold a ternary expression of code CODE and type TYPE with operands
13607 OP0, OP1, and OP2. Return the folded expression if folding is
13608 successful. Otherwise, return NULL_TREE. */
13610 tree
13613 {
13614 tree tem;
13621 /* Strip any conversions that don't change the mode. This is safe
13622 for every expression, except for a comparison expression because
13623 its signedness is derived from its operands. So, in the latter
13624 case, only strip conversions that don't change the signedness.
13626 Note that this is done as an internal manipulation within the
13627 constant folder, in order to find the simplest representation of
13628 the arguments so that their form can be studied. In any cases,
13629 the appropriate type conversions should be put back in the tree
13630 that will get out of the constant folder. */
13632 {
13635 }
13638 {
13641 }
13644 {
13648 {
13654 }
13658 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13659 so all simple results must be passed through pedantic_non_lvalue. */
13661 {
13664 /* Only optimize constant conditions when the selected branch
13665 has the same type as the COND_EXPR. This avoids optimizing
13666 away "c ? x : throw", where the throw has a void type.
13667 Avoid throwing away that operand which contains label. */
13674 }
13678 /* If we have A op B ? A : C, we may be able to convert this to a
13679 simpler expression, depending on the operation and the values
13680 of B and C. Signed zeros prevent all of these transformations,
13681 for reasons given above each one.
13683 Also try swapping the arguments and inverting the conditional. */
13688 {
13692 }
13696 op2,
13699 {
13702 {
13706 }
13707 }
13709 /* If the second operand is simpler than the third, swap them
13710 since that produces better jump optimization results. */
13713 {
13714 /* See if this can be inverted. If it can't, possibly because
13715 it was a floating-point inequality comparison, don't do
13716 anything. */
13720 }
13722 /* Convert A ? 1 : 0 to simply A. */
13725 /* If we try to convert OP0 to our type, the
13726 call to fold will try to move the conversion inside
13727 a COND, which will recurse. In that case, the COND_EXPR
13728 is probably the best choice, so leave it alone. */
13732 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13733 over COND_EXPR in cases such as floating point comparisons. */
13740 arg0)));
13742 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13747 {
13748 /* sign_bit_p only checks ARG1 bits within A's precision.
13749 If <sign bit of A> has wider type than A, bits outside
13750 of A's precision in <sign bit of A> need to be checked.
13751 If they are all 0, this optimization needs to be done
13752 in unsigned A's type, if they are all 1 in signed A's type,
13753 otherwise this can't be done. */
13758 {
13760 HOST_WIDE_INT mask_hi;
13762 tree tem_type;
13770 {
13774 }
13775 else
13776 {
13780 }
13782 {
13786 }
13787 else
13793 {
13796 }
13799 {
13802 }
13803 else
13805 }
13808 return
13814 arg1)));
13815 }
13817 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13818 already handled above. */
13823 {
13832 }
13834 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13835 is probably obsolete because the first operand should be a
13836 truth value (that's why we have the two cases above), but let's
13837 leave it in until we can confirm this for all front-ends. */
13849 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13855 arg1);
13857 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13861 {
13862 /* Only perform transformation if ARG0 is easily inverted. */
13867 arg1);
13868 }
13870 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13874 {
13875 /* Only perform transformation if ARG0 is easily inverted. */
13880 op2);
13881 }
13883 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13889 op2);
13894 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13895 of fold_ternary on them. */
13902 {
13911 {
13916 else
13917 {
13919 tree value;
13923 }
13928 else
13930 }
13931 }
13933 /* A bit-field-ref that referenced the full argument can be stripped. */
13944 }
13946 /* Perform constant folding and related simplification of EXPR.
13947 The related simplifications include x*1 => x, x*0 => 0, etc.,
13948 and application of the associative law.
13949 NOP_EXPR conversions may be removed freely (as long as we
13950 are careful not to change the type of the overall expression).
13951 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13952 but we can constant-fold them if they have constant operands. */
13954 #ifdef ENABLE_FOLD_CHECKING
13955 # define fold(x) fold_1 (x)
13957 static
13958 #endif
13959 tree
13961 {
13965 tree tem;
13968 /* Return right away if a constant. */
13972 /* CALL_EXPR-like objects with variable numbers of operands are
13973 treated specially. */
13975 {
13977 {
13980 }
13982 }
13985 {
13990 {
14008 }
14009 }
14012 {
14014 {
14021 {
14026 /* Find a matching index by means of a binary search. */
14028 {
14044 else
14046 }
14047 }
14050 }
14058 }
14060 #ifdef ENABLE_FOLD_CHECKING
14061 #undef fold
14067 /* When --enable-checking=fold, compute a digest of expr before
14068 and after actual fold call to see if fold did not accidentally
14069 change original expr. */
14071 tree
14073 {
14074 tree ret;
14077 htab_t ht;
14096 }
14098 void
14100 {
14103 htab_t ht;
14113 }
14115 static void
14117 {
14119 }
14121 static void
14123 {
14129 recursive_label:
14143 {
14144 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14148 }
14155 {
14156 /* Allow these fields to be modified. */
14157 tree tmp;
14165 {
14168 }
14169 }
14178 {
14181 {
14195 }
14199 {
14212 }
14229 {
14235 }
14240 {
14244 }
14255 {
14258 }
14268 }
14269 }
14271 /* Helper function for outputting the checksum of a tree T. When
14272 debugging with gdb, you can "define mynext" to be "next" followed
14273 by "call debug_fold_checksum (op0)", then just trace down till the
14274 outputs differ. */
14276 void
14278 {
14293 }
14295 #endif
14297 /* Fold a unary tree expression with code CODE of type TYPE with an
14298 operand OP0. LOC is the location of the resulting expression.
14299 Return a folded expression if successful. Otherwise, return a tree
14300 expression with code CODE of type TYPE with an operand OP0. */
14302 tree
14305 {
14306 tree tem;
14307 #ifdef ENABLE_FOLD_CHECKING
14310 htab_t ht;
14317 #endif
14321 {
14324 }
14326 #ifdef ENABLE_FOLD_CHECKING
14334 #endif
14336 }
14338 /* Fold a binary tree expression with code CODE of type TYPE with
14339 operands OP0 and OP1. LOC is the location of the resulting
14340 expression. Return a folded expression if successful. Otherwise,
14341 return a tree expression with code CODE of type TYPE with operands
14342 OP0 and OP1. */
14344 tree
14347 MEM_STAT_DECL)
14348 {
14349 tree tem;
14350 #ifdef ENABLE_FOLD_CHECKING
14356 htab_t ht;
14368 #endif
14372 {
14375 }
14377 #ifdef ENABLE_FOLD_CHECKING
14393 #endif
14395 }
14397 /* Fold a ternary tree expression with code CODE of type TYPE with
14398 operands OP0, OP1, and OP2. Return a folded expression if
14399 successful. Otherwise, return a tree expression with code CODE of
14400 type TYPE with operands OP0, OP1, and OP2. */
14402 tree
14405 {
14406 tree tem;
14407 #ifdef ENABLE_FOLD_CHECKING
14415 htab_t ht;
14432 #endif
14437 {
14440 }
14442 #ifdef ENABLE_FOLD_CHECKING
14466 #endif
14468 }
14470 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14471 arguments in ARGARRAY, and a null static chain.
14472 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14473 of type TYPE from the given operands as constructed by build_call_array. */
14475 tree
14478 {
14479 tree tem;
14480 #ifdef ENABLE_FOLD_CHECKING
14486 htab_t ht;
14500 #endif
14504 #ifdef ENABLE_FOLD_CHECKING
14521 #endif
14523 }
14525 /* Perform constant folding and related simplification of initializer
14526 expression EXPR. These behave identically to "fold_buildN" but ignore
14527 potential run-time traps and exceptions that fold must preserve. */
14529 #define START_FOLD_INIT \
14530 int saved_signaling_nans = flag_signaling_nans;\
14531 int saved_trapping_math = flag_trapping_math;\
14532 int saved_rounding_math = flag_rounding_math;\
14533 int saved_trapv = flag_trapv;\
14534 int saved_folding_initializer = folding_initializer;\
14535 flag_signaling_nans = 0;\
14536 flag_trapping_math = 0;\
14537 flag_rounding_math = 0;\
14538 flag_trapv = 0;\
14539 folding_initializer = 1;
14541 #define END_FOLD_INIT \
14542 flag_signaling_nans = saved_signaling_nans;\
14543 flag_trapping_math = saved_trapping_math;\
14544 flag_rounding_math = saved_rounding_math;\
14545 flag_trapv = saved_trapv;\
14546 folding_initializer = saved_folding_initializer;
14548 tree
14551 {
14552 tree result;
14553 START_FOLD_INIT;
14557 END_FOLD_INIT;
14559 }
14561 tree
14564 {
14565 tree result;
14566 START_FOLD_INIT;
14570 END_FOLD_INIT;
14572 }
14574 tree
14577 {
14578 tree result;
14579 START_FOLD_INIT;
14583 END_FOLD_INIT;
14585 }
14587 tree
14590 {
14591 tree result;
14592 START_FOLD_INIT;
14596 END_FOLD_INIT;
14598 }
14600 #undef START_FOLD_INIT
14601 #undef END_FOLD_INIT
14603 /* Determine if first argument is a multiple of second argument. Return 0 if
14604 it is not, or we cannot easily determined it to be.
14606 An example of the sort of thing we care about (at this point; this routine
14607 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14608 fold cases do now) is discovering that
14610 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14612 is a multiple of
14614 SAVE_EXPR (J * 8)
14616 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14618 This code also handles discovering that
14620 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14622 is a multiple of 8 so we don't have to worry about dealing with a
14623 possible remainder.
14625 Note that we *look* inside a SAVE_EXPR only to determine how it was
14626 calculated; it is not safe for fold to do much of anything else with the
14627 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14628 at run time. For example, the latter example above *cannot* be implemented
14629 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14630 evaluation time of the original SAVE_EXPR is not necessarily the same at
14631 the time the new expression is evaluated. The only optimization of this
14632 sort that would be valid is changing
14634 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14636 divided by 8 to
14638 SAVE_EXPR (I) * SAVE_EXPR (J)
14640 (where the same SAVE_EXPR (J) is used in the original and the
14641 transformed version). */
14643 int
14645 {
14653 {
14655 /* Bitwise and provides a power of two multiple. If the mask is
14656 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14659 /* FALLTHRU */
14672 {
14676 /* const_binop may not detect overflow correctly,
14677 so check for it explicitly here. */
14683 size_one_node,
14687 }
14691 /* Can't handle conversions from non-integral or wider integral type. */
14697 /* .. fall through ... */
14714 }
14715 }
14717 /* Return true if CODE or TYPE is known to be non-negative. */
14719 static bool
14721 {
14724 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14725 have a signed:1 type (where the value is -1 and 0). */
14728 }
14730 /* Return true if (CODE OP0) is known to be non-negative. If the return
14731 value is based on the assumption that signed overflow is undefined,
14732 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14733 *STRICT_OVERFLOW_P. */
14735 bool
14738 {
14743 {
14745 /* We can't return 1 if flag_wrapv is set because
14746 ABS_EXPR<INT_MIN> = INT_MIN. */
14750 {
14753 }
14760 strict_overflow_p);
14763 {
14768 {
14771 strict_overflow_p);
14773 {
14777 strict_overflow_p);
14778 }
14779 }
14781 {
14784 strict_overflow_p);
14788 }
14789 }
14794 }
14796 /* We don't know sign of `t', so be conservative and return false. */
14798 }
14800 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14801 value is based on the assumption that signed overflow is undefined,
14802 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14803 *STRICT_OVERFLOW_P. */
14805 bool
14808 {
14813 {
14818 strict_overflow_p)
14820 strict_overflow_p));
14822 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14823 both unsigned and at least 2 bits shorter than the result. */
14827 {
14832 {
14836 }
14837 }
14842 {
14843 /* x * x for floating point x is always non-negative. */
14847 strict_overflow_p)
14849 strict_overflow_p));
14850 }
14852 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14853 both unsigned and their total bits is shorter than the result. */
14857 {
14876 {
14886 }
14887 }
14893 strict_overflow_p)
14895 strict_overflow_p));
14906 strict_overflow_p)
14908 strict_overflow_p));
14915 strict_overflow_p);
14918 }
14920 /* We don't know sign of `t', so be conservative and return false. */
14922 }
14924 /* Return true if T is known to be non-negative. If the return
14925 value is based on the assumption that signed overflow is undefined,
14926 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14927 *STRICT_OVERFLOW_P. */
14929 bool
14931 {
14936 {
14948 strict_overflow_p)
14950 strict_overflow_p));
14954 }
14955 /* We don't know sign of `t', so be conservative and return false. */
14957 }
14959 /* Return true if T is known to be non-negative. If the return
14960 value is based on the assumption that signed overflow is undefined,
14961 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14962 *STRICT_OVERFLOW_P. */
14964 bool
14967 {
14970 {
14988 /* Always true. */
14992 /* sqrt(-0.0) is -0.0. */
14996 strict_overflow_p);
15029 /* True if the 1st argument is nonnegative. */
15031 strict_overflow_p);
15034 /* True if the 1st OR 2nd arguments are nonnegative. */
15036 strict_overflow_p)
15038 strict_overflow_p)));
15041 /* True if the 1st AND 2nd arguments are nonnegative. */
15043 strict_overflow_p)
15045 strict_overflow_p)));
15048 /* True if the 2nd argument is nonnegative. */
15050 strict_overflow_p);
15053 /* True if the 1st argument is nonnegative or the second
15054 argument is an even integer. */
15059 strict_overflow_p);
15062 /* True if the 1st argument is nonnegative or the second
15063 argument is an even integer valued real. */
15065 {
15066 REAL_VALUE_TYPE c;
15067 HOST_WIDE_INT n;
15072 {
15073 REAL_VALUE_TYPE cint;
15078 }
15079 }
15081 strict_overflow_p);
15085 }
15087 type);
15088 }
15090 /* Return true if T is known to be non-negative. If the return
15091 value is based on the assumption that signed overflow is undefined,
15092 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15093 *STRICT_OVERFLOW_P. */
15095 bool
15097 {
15103 {
15105 {
15109 /* If the initializer is non-void, then it's a normal expression
15110 that will be assigned to the slot. */
15114 /* Otherwise, the initializer sets the slot in some way. One common
15115 way is an assignment statement at the end of the initializer. */
15117 {
15125 else
15127 }
15131 strict_overflow_p);
15134 }
15137 {
15143 arg0,
15144 arg1,
15145 strict_overflow_p);
15146 }
15150 strict_overflow_p);
15153 strict_overflow_p);
15156 strict_overflow_p);
15161 }
15163 /* We don't know sign of `t', so be conservative and return false. */
15165 }
15167 /* Return true if T is known to be non-negative. If the return
15168 value is based on the assumption that signed overflow is undefined,
15169 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15170 *STRICT_OVERFLOW_P. */
15172 bool
15174 {
15181 {
15188 strict_overflow_p);
15194 strict_overflow_p);
15203 }
15206 {
15214 strict_overflow_p);
15219 strict_overflow_p);
15234 }
15235 }
15237 /* Return true if `t' is known to be non-negative. Handle warnings
15238 about undefined signed overflow. */
15240 bool
15242 {
15249 "determining that expression is always "
15251 WARN_STRICT_OVERFLOW_MISC);
15253 }
15256 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15257 For floating point we further ensure that T is not denormal.
15258 Similar logic is present in nonzero_address in rtlanal.h.
15260 If the return value is based on the assumption that signed overflow
15261 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15262 change *STRICT_OVERFLOW_P. */
15264 bool
15267 {
15269 {
15272 strict_overflow_p);
15275 {
15281 strict_overflow_p));
15282 }
15287 strict_overflow_p);
15291 }
15294 }
15296 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15297 For floating point we further ensure that T is not denormal.
15298 Similar logic is present in nonzero_address in rtlanal.h.
15300 If the return value is based on the assumption that signed overflow
15301 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15302 change *STRICT_OVERFLOW_P. */
15304 bool
15306 tree type,
15307 tree op0,
15309 {
15312 {
15316 {
15317 /* With the presence of negative values it is hard
15318 to say something. */
15325 /* One of operands must be positive and the other non-negative. */
15326 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15327 overflows, on a twos-complement machine the sum of two
15328 nonnegative numbers can never be zero. */
15330 strict_overflow_p)
15332 strict_overflow_p));
15333 }
15338 {
15340 strict_overflow_p)
15342 strict_overflow_p))
15343 {
15346 }
15347 }
15356 {
15359 }
15366 {
15370 /* When both operands are nonzero, then MAX must be too. */
15372 strict_overflow_p))
15375 /* MAX where operand 0 is positive is positive. */
15377 strict_overflow_p);
15378 }
15379 /* MAX where operand 1 is positive is positive. */
15384 {
15388 }
15393 strict_overflow_p)
15395 strict_overflow_p));
15399 }
15402 }
15404 /* Return true when T is an address and is known to be nonzero.
15405 For floating point we further ensure that T is not denormal.
15406 Similar logic is present in nonzero_address in rtlanal.h.
15408 If the return value is based on the assumption that signed overflow
15409 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15410 change *STRICT_OVERFLOW_P. */
15412 bool
15414 {
15417 {
15422 {
15428 /* Weak declarations may link to NULL. Other things may also be NULL
15429 so protect with -fdelete-null-pointer-checks; but not variables
15430 allocated on the stack. */
15432 && (flag_delete_null_pointer_checks
15436 /* Constants are never weak. */
15441 }
15449 {
15453 }
15458 }
15460 }
15462 /* Return true when T is an address and is known to be nonzero.
15463 For floating point we further ensure that T is not denormal.
15464 Similar logic is present in nonzero_address in rtlanal.h.
15466 If the return value is based on the assumption that signed overflow
15467 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15468 change *STRICT_OVERFLOW_P. */
15470 bool
15472 {
15476 /* Doing something useful for floating point would need more work. */
15482 {
15485 strict_overflow_p);
15491 strict_overflow_p);
15499 }
15502 {
15505 strict_overflow_p);
15513 strict_overflow_p);
15530 strict_overflow_p);
15534 strict_overflow_p);
15541 }
15543 }
15545 /* Return true when T is an address and is known to be nonzero.
15546 Handle warnings about undefined signed overflow. */
15548 bool
15550 {
15557 "determining that expression is always "
15559 WARN_STRICT_OVERFLOW_MISC);
15561 }
15563 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15564 attempt to fold the expression to a constant without modifying TYPE,
15565 OP0 or OP1.
15567 If the expression could be simplified to a constant, then return
15568 the constant. If the expression would not be simplified to a
15569 constant, then return NULL_TREE. */
15571 tree
15573 {
15576 }
15578 /* Given the components of a unary expression CODE, TYPE and OP0,
15579 attempt to fold the expression to a constant without modifying
15580 TYPE or OP0.
15582 If the expression could be simplified to a constant, then return
15583 the constant. If the expression would not be simplified to a
15584 constant, then return NULL_TREE. */
15586 tree
15588 {
15591 }
15593 /* If EXP represents referencing an element in a constant string
15594 (either via pointer arithmetic or array indexing), return the
15595 tree representing the value accessed, otherwise return NULL. */
15597 tree
15599 {
15603 {
15605 tree index;
15606 tree string;
15611 else
15612 {
15616 /* Optimize the special-case of a zero lower bound.
15618 We convert the low_bound to sizetype to avoid some problems
15619 with constant folding. (E.g. suppose the lower bound is 1,
15620 and its mode is QI. Without the conversion,l (ARRAY
15621 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15622 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15628 }
15641 }
15643 }
15645 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15646 an integer constant, real, or fixed-point constant.
15648 TYPE is the type of the result. */
15650 static tree
15652 {
15656 {
15658 {
15660 HOST_WIDE_INT high;
15668 }
15675 {
15676 FIXED_VALUE_TYPE f;
15681 /* Propagate overflow flags. */
15685 }
15689 }
15692 }
15694 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15695 an integer constant or real constant.
15697 TYPE is the type of the result. */
15699 tree
15701 {
15705 {
15707 /* If the value is unsigned, then the absolute value is
15708 the same as the ordinary value. */
15711 /* Similarly, if the value is non-negative. */
15714 /* If the value is negative, then the absolute value is
15715 its negation. */
15716 else
15717 {
15719 HOST_WIDE_INT high;
15725 }
15731 else
15737 }
15740 }
15742 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15743 constant. TYPE is the type of the result. */
15745 static tree
15747 {
15757 }
15759 /* Given CODE, a relational operator, the target type, TYPE and two
15760 constant operands OP0 and OP1, return the result of the
15761 relational operation. If the result is not a compile time
15762 constant, then return NULL_TREE. */
15764 static tree
15766 {
15769 /* From here on, the only cases we handle are when the result is
15770 known to be a constant. */
15773 {
15777 /* Handle the cases where either operand is a NaN. */
15779 {
15781 {
15809 }
15812 }
15815 }
15818 {
15822 }
15824 /* Handle equality/inequality of complex constants. */
15826 {
15837 else
15839 }
15841 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15843 To compute GT, swap the arguments and do LT.
15844 To compute GE, do LT and invert the result.
15845 To compute LE, swap the arguments, do LT and invert the result.
15846 To compute NE, do EQ and invert the result.
15848 Therefore, the code below must handle only EQ and LT. */
15851 {
15856 }
15858 /* Note that it is safe to invert for real values here because we
15859 have already handled the one case that it matters. */
15863 {
15866 }
15868 /* Compute a result for LT or EQ if args permit;
15869 Otherwise return T. */
15871 {
15876 else
15878 }
15879 else
15885 }
15887 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15888 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15889 itself. */
15891 tree
15893 {
15894 /* If the expression does not have side effects then we don't have to wrap
15895 it with a cleanup point expression. */
15899 /* If the expression is a return, check to see if the expression inside the
15900 return has no side effects or the right hand side of the modify expression
15901 inside the return. If either don't have side effects set we don't need to
15902 wrap the expression in a cleanup point expression. Note we don't check the
15903 left hand side of the modify because it should always be a return decl. */
15905 {
15912 }
15915 }
15917 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15918 of an indirection through OP0, or NULL_TREE if no simplification is
15919 possible. */
15921 tree
15923 {
15925 tree subtype;
15933 {
15936 /* *&CONST_DECL -> to the value of the const decl. */
15939 /* *&p => p; make sure to handle *&"str"[cst] here. */
15941 {
15945 else
15947 }
15948 /* *(foo *)&fooarray => fooarray[0] */
15951 {
15959 }
15960 /* *(foo *)&complexfoo => __real__ complexfoo */
15964 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15967 {
15971 }
15972 }
15974 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15977 {
15980 tree op00type;
15987 {
15999 }
16000 }
16003 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16006 {
16009 tree op00type;
16016 {
16021 }
16022 }
16024 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16027 {
16028 tree type_domain;
16037 }
16040 }
16042 /* Builds an expression for an indirection through T, simplifying some
16043 cases. */
16045 tree
16047 {
16057 }
16059 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16061 tree
16063 {
16068 else
16070 }
16072 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16073 whose result is ignored. The type of the returned tree need not be
16074 the same as the original expression. */
16076 tree
16078 {
16084 {
16095 else
16101 {
16117 }
16122 }
16123 }
16125 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
16126 This can only be applied to objects of a sizetype. */
16128 tree
16130 {
16137 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16138 have to do anything. Only do this when we are not given a const,
16139 because in that case, this check is more expensive than just
16140 doing it. */
16142 {
16147 }
16149 /* If divisor is a power of two, simplify this to bit manipulation. */
16151 {
16153 {
16166 {
16167 high++;
16170 }
16174 }
16175 else
16176 {
16177 tree t;
16183 }
16184 }
16185 else
16186 {
16191 }
16194 }
16196 /* Likewise, but round down. */
16198 tree
16200 {
16207 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16208 have to do anything. Only do this when we are not given a const,
16209 because in that case, this check is more expensive than just
16210 doing it. */
16212 {
16217 }
16219 /* If divisor is a power of two, simplify this to bit manipulation. */
16221 {
16222 tree t;
16226 }
16227 else
16228 {
16233 }
16236 }
16238 /* Returns the pointer to the base of the object addressed by EXP and
16239 extracts the information about the offset of the access, storing it
16240 to PBITPOS and POFFSET. */
16242 static tree
16245 {
16246 tree core;
16249 HOST_WIDE_INT bitsize;
16253 {
16258 }
16259 else
16260 {
16264 }
16267 }
16269 /* Returns true if addresses of E1 and E2 differ by a constant, false
16270 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16272 bool
16274 {
16288 {
16298 }
16300 {
16301 /* If only one of the offsets is non-constant, the difference cannot
16302 be a constant. */
16304 }
16305 else
16310 }
16312 /* Simplify the floating point expression EXP when the sign of the
16313 result is not significant. Return NULL_TREE if no simplification
16314 is possible. */
16316 tree
16318 {
16323 {
16359 {
16362 {
16364 /* Strip copysign function call, return the 1st argument. */
16370 /* Strip sign ops from the argument of "odd" math functions. */
16372 {
16376 }
16378 }
16379 }
16384 }
16386 }