| blob | da4d50d5e9496e4931d239c7631362d0405f662e |
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 };
127 tree);
148 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
149 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
150 and SUM1. Then this yields nonzero if overflow occurred during the
151 addition.
153 Overflow occurs if A and B have the same sign, but A and SUM differ in
154 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
155 sign. */
156 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
157 \f
158 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
159 We do that by representing the two-word integer in 4 words, with only
160 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
161 number. The value of the word is LOWPART + HIGHPART * BASE. */
163 #define LOWPART(x) \
164 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
165 #define HIGHPART(x) \
166 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
167 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
169 /* Unpack a two-word integer into 4 words.
170 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
171 WORDS points to the array of HOST_WIDE_INTs. */
173 static void
175 {
180 }
182 /* Pack an array of 4 words into a two-word integer.
183 WORDS points to the array of words.
184 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
186 static void
189 {
192 }
193 \f
194 /* Force the double-word integer L1, H1 to be within the range of the
195 integer type TYPE. Stores the properly truncated and sign-extended
196 double-word integer in *LV, *HV. Returns true if the operation
197 overflows, that is, argument and result are different. */
199 int
202 {
211 else
214 /* Size types *are* sign extended. */
219 /* First clear all bits that are beyond the type's precision. */
221 ;
224 else
225 {
229 }
231 /* Then do sign extension if necessary. */
237 {
238 /* Sign extend top half? */
242 }
244 {
247 }
248 else
249 {
250 /* Sign extend bottom half? */
252 {
255 }
256 }
261 /* If the value didn't fit, signal overflow. */
263 }
265 /* We force the double-int HIGH:LOW to the range of the type TYPE by
266 sign or zero extending it.
267 OVERFLOWABLE indicates if we are interested
268 in overflow of the value, when >0 we are only interested in signed
269 overflow, for <0 we are interested in any overflow. OVERFLOWED
270 indicates whether overflow has already occurred. CONST_OVERFLOWED
271 indicates whether constant overflow has already occurred. We force
272 T's value to be within range of T's type (by setting to 0 or 1 all
273 the bits outside the type's range). We set TREE_OVERFLOWED if,
274 OVERFLOWED is nonzero,
275 or OVERFLOWABLE is >0 and signed overflow occurs
276 or OVERFLOWABLE is <0 and any overflow occurs
277 We return a new tree node for the extended double-int. The node
278 is shared if no overflow flags are set. */
280 tree
284 {
288 /* Size types *are* sign extended. */
295 /* If we need to set overflow flags, return a new unshared node. */
297 {
301 {
308 }
309 }
311 /* Else build a shared node. */
313 }
314 \f
315 /* Add two doubleword integers with doubleword result.
316 Return nonzero if the operation overflows according to UNSIGNED_P.
317 Each argument is given as two `HOST_WIDE_INT' pieces.
318 One argument is L1 and H1; the other, L2 and H2.
319 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
321 int
326 {
328 HOST_WIDE_INT h;
338 else
340 }
342 /* Negate a doubleword integer with doubleword result.
343 Return nonzero if the operation overflows, assuming it's signed.
344 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
345 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
347 int
350 {
352 {
356 }
357 else
358 {
362 }
363 }
364 \f
365 /* Multiply two doubleword integers with doubleword result.
366 Return nonzero if the operation overflows according to UNSIGNED_P.
367 Each argument is given as two `HOST_WIDE_INT' pieces.
368 One argument is L1 and H1; the other, L2 and H2.
369 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
371 int
376 {
391 {
394 {
396 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
398 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
402 }
404 }
409 /* Unsigned overflow is immediate. */
413 /* Check for signed overflow by calculating the signed representation of the
414 top half of the result; it should agree with the low half's sign bit. */
416 {
419 }
421 {
424 }
426 }
427 \f
428 /* Shift the doubleword integer in L1, H1 left by COUNT places
429 keeping only PREC bits of result.
430 Shift right if COUNT is negative.
431 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
432 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
434 void
438 {
442 {
445 }
451 {
452 /* Shifting by the host word size is undefined according to the
453 ANSI standard, so we must handle this as a special case. */
456 }
458 {
461 }
462 else
463 {
467 }
469 /* Sign extend all bits that are beyond the precision. */
477 ;
479 {
482 }
483 else
484 {
488 }
489 }
491 /* Shift the doubleword integer in L1, H1 right by COUNT places
492 keeping only PREC bits of result. COUNT must be positive.
493 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
494 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
496 void
501 {
504 signmask = (arith
512 {
513 /* Shifting by the host word size is undefined according to the
514 ANSI standard, so we must handle this as a special case. */
517 }
519 {
522 }
523 else
524 {
528 }
530 /* Zero / sign extend all bits that are beyond the precision. */
533 {
536 }
538 ;
540 {
543 }
544 else
545 {
549 }
550 }
551 \f
552 /* Rotate the doubleword integer in L1, H1 left by COUNT places
553 keeping only PREC bits of result.
554 Rotate right if COUNT is negative.
555 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
557 void
561 {
573 }
575 /* Rotate the doubleword integer in L1, H1 left by COUNT places
576 keeping only PREC bits of result. COUNT must be positive.
577 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
579 void
583 {
595 }
596 \f
597 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
598 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
599 CODE is a tree code for a kind of division, one of
600 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
601 or EXACT_DIV_EXPR
602 It controls how the quotient is rounded to an integer.
603 Return nonzero if the operation overflows.
604 UNS nonzero says do unsigned division. */
606 int
609 HOST_WIDE_INT hnum_orig,
611 HOST_WIDE_INT hden_orig,
615 {
631 /* Calculate quotient sign and convert operands to unsigned. */
633 {
635 {
637 /* (minimum integer) / (-1) is the only overflow case. */
641 }
643 {
646 }
647 }
652 /* This unsigned division rounds toward zero. */
655 }
659 /* hden != 0 already checked. */
664 }
674 /* Special code for when the divisor < BASE. */
676 {
677 /* hnum != 0 already checked. */
679 {
683 }
684 }
685 else
686 {
687 /* Full double precision division,
688 with thanks to Don Knuth's "Seminumerical Algorithms". */
692 /* Find the highest nonzero divisor digit. */
695 {
698 }
700 /* Insure that the first digit of the divisor is at least BASE/2.
701 This is required by the quotient digit estimation algorithm. */
708 {
712 }
717 {
722 }
723 }
727 /* Main loop */
729 {
730 /* Guess the next quotient digit, quo_est, by dividing the first
731 two remaining dividend digits by the high order quotient digit.
732 quo_est is never low and is at most 2 high. */
739 else
742 /* Refine quo_est so it's usually correct, and at most one high. */
747 quo_est--;
749 /* Try QUO_EST as the quotient digit, by multiplying the
750 divisor by QUO_EST and subtracting from the remaining dividend.
751 Keep in mind that QUO_EST is the I - 1st digit. */
755 {
761 }
763 /* If quo_est was high by one, then num[i] went negative and
764 we need to correct things. */
766 {
767 quo_est--;
770 {
774 }
777 }
779 /* Store the quotient digit. */
781 }
782 }
786 finish_up:
787 /* If result is negative, make it so. */
791 /* Compute trial remainder: rem = num - (quo * den) */
797 {
806 {
807 /* quo = quo - 1; */
810 }
811 else
818 {
821 }
822 else
828 {
834 /* Get absolute values. */
840 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
849 {
851 /* quo = quo - 1; */
854 else
855 /* quo = quo + 1; */
858 }
859 else
861 }
866 }
868 /* Compute true remainder: rem = num - (quo * den) */
873 }
875 /* If ARG2 divides ARG1 with zero remainder, carries out the division
876 of type CODE and returns the quotient.
877 Otherwise returns NULL_TREE. */
879 static tree
881 {
891 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
892 &obj[some_exotic_number]. */
894 {
898 type);
899 }
900 else
911 }
912 \f
913 /* This is nonzero if we should defer warnings about undefined
914 overflow. This facility exists because these warnings are a
915 special case. The code to estimate loop iterations does not want
916 to issue any warnings, since it works with expressions which do not
917 occur in user code. Various bits of cleanup code call fold(), but
918 only use the result if it has certain characteristics (e.g., is a
919 constant); that code only wants to issue a warning if the result is
920 used. */
924 /* If a warning about undefined overflow is deferred, this is the
925 warning. Note that this may cause us to turn two warnings into
926 one, but that is fine since it is sufficient to only give one
927 warning per expression. */
931 /* If a warning about undefined overflow is deferred, this is the
932 level at which the warning should be emitted. */
936 /* Start deferring overflow warnings. We could use a stack here to
937 permit nested calls, but at present it is not necessary. */
939 void
941 {
943 }
945 /* Stop deferring overflow warnings. If there is a pending warning,
946 and ISSUE is true, then issue the warning if appropriate. STMT is
947 the statement with which the warning should be associated (used for
948 location information); STMT may be NULL. CODE is the level of the
949 warning--a warn_strict_overflow_code value. This function will use
950 the smaller of CODE and the deferred code when deciding whether to
951 issue the warning. CODE may be zero to mean to always use the
952 deferred code. */
954 void
956 {
958 location_t locus;
963 {
969 }
980 /* Use the smallest code level when deciding to issue the
981 warning. */
990 else
993 }
995 /* Stop deferring overflow warnings, ignoring any deferred
996 warnings. */
998 void
1000 {
1002 }
1004 /* Whether we are deferring overflow warnings. */
1006 bool
1008 {
1010 }
1012 /* This is called when we fold something based on the fact that signed
1013 overflow is undefined. */
1015 static void
1017 {
1019 {
1022 {
1025 }
1026 }
1029 }
1030 \f
1031 /* Return true if the built-in mathematical function specified by CODE
1032 is odd, i.e. -f(x) == f(-x). */
1034 static bool
1036 {
1038 {
1072 }
1074 }
1076 /* Check whether we may negate an integer constant T without causing
1077 overflow. */
1079 bool
1081 {
1084 tree type;
1094 {
1099 }
1100 else
1105 }
1107 /* Determine whether an expression T can be cheaply negated using
1108 the function negate_expr without introducing undefined overflow. */
1110 static bool
1112 {
1113 tree type;
1122 {
1127 /* Check that -CST will not overflow type. */
1153 /* -(A + B) -> (-B) - A. */
1158 /* -(A + B) -> (-A) - B. */
1162 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1172 /* Fall through. */
1185 /* In general we can't negate A / B, because if A is INT_MIN and
1186 B is 1, we may turn this into INT_MIN / -1 which is undefined
1187 and actually traps on some architectures. But if overflow is
1188 undefined, we can negate, because - (INT_MIN / 1) is an
1189 overflow. */
1197 /* Negate -((double)float) as (double)(-float). */
1199 {
1203 }
1207 /* Negate -f(x) as f(-x). */
1213 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1215 {
1221 }
1226 }
1228 }
1230 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1231 simplification is possible.
1232 If negate_expr_p would return true for T, NULL_TREE will never be
1233 returned. */
1235 static tree
1237 {
1239 tree tem;
1242 {
1243 /* Convert - (~A) to A + 1. */
1259 /* Two's complement FP formats, such as c4x, may overflow. */
1269 {
1278 }
1300 {
1301 /* -(A + B) -> (-B) - A. */
1305 {
1309 }
1311 /* -(A + B) -> (-A) - B. */
1313 {
1317 }
1318 }
1322 /* - (A - B) -> B - A */
1334 /* Fall through. */
1338 {
1347 }
1355 /* In general we can't negate A / B, because if A is INT_MIN and
1356 B is 1, we may turn this into INT_MIN / -1 which is undefined
1357 and actually traps on some architectures. But if overflow is
1358 undefined, we can negate, because - (INT_MIN / 1) is an
1359 overflow. */
1361 {
1366 {
1373 }
1376 {
1383 }
1384 }
1388 /* Convert -((double)float) into (double)(-float). */
1390 {
1394 }
1398 /* Negate -f(x) as f(-x). */
1401 {
1407 }
1411 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1413 {
1418 {
1425 }
1426 }
1431 }
1434 }
1436 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1437 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1438 return NULL_TREE. */
1440 static tree
1442 {
1455 }
1456 \f
1457 /* Split a tree IN into a constant, literal and variable parts that could be
1458 combined with CODE to make IN. "constant" means an expression with
1459 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1460 commutative arithmetic operation. Store the constant part into *CONP,
1461 the literal in *LITP and return the variable part. If a part isn't
1462 present, set it to null. If the tree does not decompose in this way,
1463 return the entire tree as the variable part and the other parts as null.
1465 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1466 case, we negate an operand that was subtracted. Except if it is a
1467 literal for which we use *MINUS_LITP instead.
1469 If NEGATE_P is true, we are negating all of IN, again except a literal
1470 for which we use *MINUS_LITP instead.
1472 If IN is itself a literal or constant, return it as appropriate.
1474 Note that we do not guarantee that any of the three values will be the
1475 same type as IN, but they will have the same signedness and mode. */
1477 static tree
1480 {
1487 /* Strip any conversions that don't change the machine mode or signedness. */
1496 /* We can associate addition and subtraction together (even
1497 though the C standard doesn't say so) for integers because
1498 the value is not affected. For reals, the value might be
1499 affected, so we can't. */
1502 {
1508 /* First see if either of the operands is a literal, then a constant. */
1521 /* If we haven't dealt with either operand, this is not a case we can
1522 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1527 else
1530 /* Now do any needed negations. */
1537 }
1540 else
1544 {
1551 }
1554 }
1556 /* Re-associate trees split by the above function. T1 and T2 are either
1557 expressions to associate or null. Return the new expression, if any. If
1558 we build an operation, do it in TYPE and with CODE. */
1560 static tree
1562 {
1568 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1569 try to fold this since we will have infinite recursion. But do
1570 deal with any NEGATE_EXPRs. */
1573 {
1575 {
1584 }
1586 {
1589 }
1593 }
1597 }
1598 \f
1599 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1600 for use in int_const_binop, size_binop and size_diffop. */
1602 static bool
1604 {
1611 {
1620 }
1625 }
1628 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1629 to produce a new constant. Return NULL_TREE if we don't know how
1630 to evaluate CODE at compile-time.
1632 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1634 tree
1636 {
1640 HOST_WIDE_INT hi;
1642 HOST_WIDE_INT garbageh;
1643 tree t;
1646 int is_sizetype
1656 {
1672 /* It's unclear from the C standard whether shifts can overflow.
1673 The following code ignores overflow; perhaps a C standard
1674 interpretation ruling is needed. */
1703 /* This is a shortcut for a common special case. */
1708 {
1714 }
1716 /* ... fall through ... */
1722 {
1725 }
1728 {
1731 }
1738 /* This is a shortcut for a common special case. */
1743 {
1748 }
1750 /* ... fall through ... */
1768 else
1774 else
1780 }
1783 {
1786 /* Propagate overflow flags ourselves. */
1789 {
1792 }
1793 }
1794 else
1800 }
1802 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1803 constant. We assume ARG1 and ARG2 have the same data type, or at least
1804 are the same kind of constant and the same machine mode. Return zero if
1805 combining the constants is not allowed in the current operating mode.
1807 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1809 static tree
1811 {
1812 /* Sanity check for the recursive cases. */
1823 {
1825 REAL_VALUE_TYPE d1;
1826 REAL_VALUE_TYPE d2;
1827 REAL_VALUE_TYPE value;
1828 REAL_VALUE_TYPE result;
1832 /* The following codes are handled by real_arithmetic. */
1834 {
1845 }
1853 /* Don't perform operation if we honor signaling NaNs and
1854 either operand is a NaN. */
1859 /* Don't perform operation if it would raise a division
1860 by zero exception. */
1866 /* If either operand is a NaN, just return it. Otherwise, set up
1867 for floating-point trap; we return an overflow. */
1876 /* Don't constant fold this floating point operation if
1877 the result has overflowed and flag_trapping_math. */
1885 /* Don't constant fold this floating point operation if the
1886 result may dependent upon the run-time rounding mode and
1887 flag_rounding_math is set, or if GCC's software emulation
1888 is unable to accurately represent the result. */
1898 }
1901 {
1902 FIXED_VALUE_TYPE f1;
1903 FIXED_VALUE_TYPE f2;
1904 FIXED_VALUE_TYPE result;
1909 /* The following codes are handled by fixed_arithmetic. */
1911 {
1928 }
1935 /* Propagate overflow flags. */
1937 {
1940 }
1944 }
1947 {
1956 {
1967 notrunc);
1971 notrunc);
1975 {
1976 tree magsquared
1980 notrunc);
1981 tree t1
1985 notrunc);
1986 tree t2
1990 notrunc);
1997 }
2002 }
2006 }
2009 }
2011 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2012 indicates which particular sizetype to create. */
2014 tree
2016 {
2018 }
2019 \f
2020 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2021 is a tree code. The type of the result is taken from the operands.
2022 Both must be equivalent integer types, ala int_binop_types_match_p.
2023 If the operands are constant, so is the result. */
2025 tree
2027 {
2036 /* Handle the special case of two integer constants faster. */
2038 {
2039 /* And some specific cases even faster than that. */
2041 {
2046 }
2048 {
2051 }
2053 {
2056 }
2058 /* Handle general case of two integer constants. */
2060 }
2063 }
2065 /* Given two values, either both of sizetype or both of bitsizetype,
2066 compute the difference between the two values. Return the value
2067 in signed type corresponding to the type of the operands. */
2069 tree
2071 {
2073 tree ctype;
2078 /* If the type is already signed, just do the simple thing. */
2086 else
2089 /* If either operand is not a constant, do the conversions to the signed
2090 type and subtract. The hardware will do the right thing with any
2091 overflow in the subtraction. */
2096 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2097 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2098 overflow) and negate (which can't either). Special-case a result
2099 of zero while we're here. */
2104 else
2108 }
2109 \f
2110 /* A subroutine of fold_convert_const handling conversions of an
2111 INTEGER_CST to another integer type. */
2113 static tree
2115 {
2116 tree t;
2118 /* Given an integer constant, make new constant with new type,
2119 appropriately sign-extended or truncated. */
2122 /* Don't set the overflow when
2123 converting from a pointer, */
2125 /* or to a sizetype with same signedness
2126 and the precision is unchanged.
2127 ??? sizetype is always sign-extended,
2128 but its signedness depends on the
2129 frontend. Thus we see spurious overflows
2130 here if we do not check this. */
2145 }
2147 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2148 to an integer type. */
2150 static tree
2152 {
2154 tree t;
2156 /* The following code implements the floating point to integer
2157 conversion rules required by the Java Language Specification,
2158 that IEEE NaNs are mapped to zero and values that overflow
2159 the target precision saturate, i.e. values greater than
2160 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2161 are mapped to INT_MIN. These semantics are allowed by the
2162 C and C++ standards that simply state that the behavior of
2163 FP-to-integer conversion is unspecified upon overflow. */
2166 REAL_VALUE_TYPE r;
2170 {
2177 }
2179 /* If R is NaN, return zero and show we have an overflow. */
2181 {
2185 }
2187 /* See if R is less than the lower bound or greater than the
2188 upper bound. */
2191 {
2195 {
2199 }
2200 }
2203 {
2206 {
2209 {
2213 }
2214 }
2215 }
2223 }
2225 /* A subroutine of fold_convert_const handling conversions of a
2226 FIXED_CST to an integer type. */
2228 static tree
2230 {
2231 tree t;
2235 /* Right shift FIXED_CST to temp by fbit. */
2239 {
2244 /* Left shift temp to temp_trunc by fbit. */
2249 }
2250 else
2251 {
2256 }
2258 /* If FIXED_CST is negative, we need to round the value toward 0.
2259 By checking if the fractional bits are not zero to add 1 to temp. */
2262 {
2263 double_int one;
2267 }
2269 /* Given a fixed-point constant, make new constant with new type,
2270 appropriately sign-extended or truncated. */
2278 }
2280 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2281 to another floating point type. */
2283 static tree
2285 {
2286 REAL_VALUE_TYPE value;
2287 tree t;
2294 }
2296 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2297 to a floating point type. */
2299 static tree
2301 {
2302 REAL_VALUE_TYPE value;
2303 tree t;
2312 }
2314 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2315 to another fixed-point type. */
2317 static tree
2319 {
2320 FIXED_VALUE_TYPE value;
2321 tree t;
2328 /* Propagate overflow flags. */
2330 {
2333 }
2337 }
2339 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2340 to a fixed-point type. */
2342 static tree
2344 {
2345 FIXED_VALUE_TYPE value;
2346 tree t;
2355 /* Propagate overflow flags. */
2357 {
2360 }
2364 }
2366 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2367 to a fixed-point type. */
2369 static tree
2371 {
2372 FIXED_VALUE_TYPE value;
2373 tree t;
2381 /* Propagate overflow flags. */
2383 {
2386 }
2390 }
2392 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2393 type TYPE. If no simplification can be done return NULL_TREE. */
2395 static tree
2397 {
2403 {
2410 }
2412 {
2419 }
2421 {
2428 }
2430 }
2432 /* Construct a vector of zero elements of vector type TYPE. */
2434 static tree
2436 {
2447 }
2449 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2451 bool
2453 {
2468 {
2487 }
2488 }
2490 /* Convert expression ARG to type TYPE. Used by the middle-end for
2491 simple conversions in preference to calling the front-end's convert. */
2493 tree
2495 {
2497 tree tem;
2511 {
2516 {
2520 }
2525 {
2528 }
2535 {
2539 }
2541 {
2545 }
2547 {
2551 }
2554 {
2572 }
2577 {
2581 }
2584 {
2598 }
2602 {
2612 {
2616 {
2620 }
2628 }
2632 }
2650 }
2651 }
2652 \f
2653 /* Return false if expr can be assumed not to be an lvalue, true
2654 otherwise. */
2656 static bool
2658 {
2659 /* We only need to wrap lvalue tree codes. */
2661 {
2695 /* Assume the worst for front-end tree codes. */
2699 }
2702 }
2704 /* Return an expr equal to X but certainly not valid as an lvalue. */
2706 tree
2708 {
2709 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2710 us. */
2717 }
2719 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2720 Zero means allow extended lvalues. */
2724 /* When pedantic, return an expr equal to X but certainly not valid as a
2725 pedantic lvalue. Otherwise, return X. */
2727 static tree
2729 {
2732 else
2734 }
2735 \f
2736 /* Given a tree comparison code, return the code that is the logical inverse
2737 of the given code. It is not safe to do this for floating-point
2738 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2739 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2741 enum tree_code
2743 {
2748 {
2779 }
2780 }
2782 /* Similar, but return the comparison that results if the operands are
2783 swapped. This is safe for floating-point. */
2785 enum tree_code
2787 {
2789 {
2815 }
2816 }
2819 /* Convert a comparison tree code from an enum tree_code representation
2820 into a compcode bit-based encoding. This function is the inverse of
2821 compcode_to_comparison. */
2823 static enum comparison_code
2825 {
2827 {
2858 }
2859 }
2861 /* Convert a compcode bit-based encoding of a comparison operator back
2862 to GCC's enum tree_code representation. This function is the
2863 inverse of comparison_to_compcode. */
2865 static enum tree_code
2867 {
2869 {
2900 }
2901 }
2903 /* Return a tree for the comparison which is the combination of
2904 doing the AND or OR (depending on CODE) of the two operations LCODE
2905 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2906 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2907 if this makes the transformation invalid. */
2909 tree
2913 {
2920 {
2931 }
2934 {
2935 /* Eliminate unordered comparisons, as well as LTGT and ORD
2936 which are not used unless the mode has NaNs. */
2942 }
2944 {
2945 /* Check that the original operation and the optimized ones will trap
2946 under the same condition. */
2957 /* In a short-circuited boolean expression the LHS might be
2958 such that the RHS, if evaluated, will never trap. For
2959 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2960 if neither x nor y is NaN. (This is a mixed blessing: for
2961 example, the expression above will never trap, hence
2962 optimizing it to x < y would be invalid). */
2967 /* If the comparison was short-circuited, and only the RHS
2968 trapped, we may now generate a spurious trap. */
2973 /* If we changed the conditions that cause a trap, we lose. */
2976 }
2982 else
2985 }
2986 \f
2987 /* Return nonzero if two operands (typically of the same tree node)
2988 are necessarily equal. If either argument has side-effects this
2989 function returns zero. FLAGS modifies behavior as follows:
2991 If OEP_ONLY_CONST is set, only return nonzero for constants.
2992 This function tests whether the operands are indistinguishable;
2993 it does not test whether they are equal using C's == operation.
2994 The distinction is important for IEEE floating point, because
2995 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2996 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2998 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2999 even though it may hold multiple values during a function.
3000 This is because a GCC tree node guarantees that nothing else is
3001 executed between the evaluation of its "operands" (which may often
3002 be evaluated in arbitrary order). Hence if the operands themselves
3003 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3004 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3005 unset means assuming isochronic (or instantaneous) tree equivalence.
3006 Unless comparing arbitrary expression trees, such as from different
3007 statements, this flag can usually be left unset.
3009 If OEP_PURE_SAME is set, then pure functions with identical arguments
3010 are considered the same. It is used when the caller has other ways
3011 to ensure that global memory is unchanged in between. */
3013 int
3015 {
3016 /* If either is ERROR_MARK, they aren't equal. */
3020 /* Check equality of integer constants before bailing out due to
3021 precision differences. */
3025 /* If both types don't have the same signedness, then we can't consider
3026 them equal. We must check this before the STRIP_NOPS calls
3027 because they may change the signedness of the arguments. As pointers
3028 strictly don't have a signedness, require either two pointers or
3029 two non-pointers as well. */
3034 /* If both types don't have the same precision, then it is not safe
3035 to strip NOPs. */
3042 /* In case both args are comparisons but with different comparison
3043 code, try to swap the comparison operands of one arg to produce
3044 a match and compare that variant. */
3048 {
3056 }
3059 /* This is needed for conversions and for COMPONENT_REF.
3060 Might as well play it safe and always test this. */
3066 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3067 We don't care about side effects in that case because the SAVE_EXPR
3068 takes care of that for us. In all other cases, two expressions are
3069 equal if they have no side effects. If we have two identical
3070 expressions with side effects that should be treated the same due
3071 to the only side effects being identical SAVE_EXPR's, that will
3072 be detected in the recursive calls below. */
3078 /* Next handle constant cases, those for which we can return 1 even
3079 if ONLY_CONST is set. */
3082 {
3097 {
3098 /* If we do not distinguish between signed and unsigned zero,
3099 consider them equal. */
3102 }
3106 {
3112 {
3114 flags))
3118 }
3121 }
3125 flags)
3127 flags));
3140 }
3145 /* Define macros to test an operand from arg0 and arg1 for equality and a
3146 variant that allows null and views null as being different from any
3147 non-null value. In the latter case, if either is null, the both
3148 must be; otherwise, do the normal comparison. */
3149 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3150 TREE_OPERAND (arg1, N), flags)
3152 #define OP_SAME_WITH_NULL(N) \
3153 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3154 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3157 {
3159 /* Two conversions are equal only if signedness and modes match. */
3161 {
3162 CASE_CONVERT:
3170 }
3180 /* For commutative ops, allow the other order. */
3188 /* If either of the pointer (or reference) expressions we are
3189 dereferencing contain a side effect, these cannot be equal. */
3195 {
3205 /* Operands 2 and 3 may be null.
3206 Compare the array index by value if it is constant first as we
3207 may have different types but same value here. */
3216 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3217 may be NULL when we're called to compare MEM_EXPRs. */
3227 }
3231 {
3246 /* Otherwise take into account this is a commutative operation. */
3257 }
3261 {
3263 /* If the CALL_EXPRs call different functions, then they
3264 clearly can not be equal. */
3266 flags))
3269 {
3273 else
3277 }
3279 /* Now see if all the arguments are the same. */
3280 {
3291 /* If we get here and both argument lists are exhausted
3292 then the CALL_EXPRs are equal. */
3294 }
3297 }
3300 /* Consider __builtin_sqrt equal to sqrt. */
3308 }
3310 #undef OP_SAME
3311 #undef OP_SAME_WITH_NULL
3312 }
3313 \f
3314 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3315 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3317 When in doubt, return 0. */
3319 static int
3321 {
3333 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3334 and see if the inner values are the same. This removes any
3335 signedness comparison, which doesn't matter here. */
3342 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3343 actual comparison operand, ARG0.
3345 First throw away any conversions to wider types
3346 already present in the operands. */
3355 {
3358 /* Make sure shorter operand is extended the right way
3359 to match the longer operand. */
3365 }
3368 }
3369 \f
3370 /* See if ARG is an expression that is either a comparison or is performing
3371 arithmetic on comparisons. The comparisons must only be comparing
3372 two different values, which will be stored in *CVAL1 and *CVAL2; if
3373 they are nonzero it means that some operands have already been found.
3374 No variables may be used anywhere else in the expression except in the
3375 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3376 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3378 If this is true, return 1. Otherwise, return zero. */
3380 static int
3382 {
3386 /* We can handle some of the tcc_expression cases here. */
3396 {
3397 /* If we've already found a CVAL1 or CVAL2, this expression is
3398 two complex to handle. */
3404 }
3407 {
3430 /* First see if we can handle the first operand, then the second. For
3431 the second operand, we know *CVAL1 can't be zero. It must be that
3432 one side of the comparison is each of the values; test for the
3433 case where this isn't true by failing if the two operands
3434 are the same. */
3443 ;
3447 ;
3448 else
3452 ;
3456 ;
3457 else
3464 }
3465 }
3466 \f
3467 /* ARG is a tree that is known to contain just arithmetic operations and
3468 comparisons. Evaluate the operations in the tree substituting NEW0 for
3469 any occurrence of OLD0 as an operand of a comparison and likewise for
3470 NEW1 and OLD1. */
3472 static tree
3474 {
3479 /* We can handle some of the tcc_expression cases here. */
3487 {
3502 {
3519 }
3520 /* Fall through - ??? */
3523 {
3527 /* We need to check both for exact equality and tree equality. The
3528 former will be true if the operand has a side-effect. In that
3529 case, we know the operand occurred exactly once. */
3542 }
3546 }
3547 }
3548 \f
3549 /* Return a tree for the case when the result of an expression is RESULT
3550 converted to TYPE and OMITTED was previously an operand of the expression
3551 but is now not needed (e.g., we folded OMITTED * 0).
3553 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3554 the conversion of RESULT to TYPE. */
3556 tree
3558 {
3561 /* If the resulting operand is an empty statement, just return the omitted
3562 statement casted to void. */
3570 }
3572 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3574 static tree
3576 {
3579 /* If the resulting operand is an empty statement, just return the omitted
3580 statement casted to void. */
3588 }
3590 /* Return a tree for the case when the result of an expression is RESULT
3591 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3592 of the expression but are now not needed.
3594 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3595 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3596 evaluated before OMITTED2. Otherwise, if neither has side effects,
3597 just do the conversion of RESULT to TYPE. */
3599 tree
3601 {
3610 }
3612 \f
3613 /* Return a simplified tree node for the truth-negation of ARG. This
3614 never alters ARG itself. We assume that ARG is an operation that
3615 returns a truth value (0 or 1).
3617 FIXME: one would think we would fold the result, but it causes
3618 problems with the dominator optimizer. */
3620 tree
3622 {
3626 /* If this is a comparison, we can simply invert it, except for
3627 floating-point non-equality comparisons, in which case we just
3628 enclose a TRUTH_NOT_EXPR around what we have. */
3631 {
3634 && flag_trapping_math
3638 else
3639 {
3644 else
3647 }
3648 }
3651 {
3666 /* Here we can invert either operand. We invert the first operand
3667 unless the second operand is a TRUTH_NOT_EXPR in which case our
3668 result is the XOR of the first operand with the inside of the
3669 negation of the second operand. */
3674 else
3693 {
3696 /* A COND_EXPR may have a throw as one operand, which
3697 then has void type. Just leave void operands
3698 as they are. */
3704 }
3737 }
3740 }
3742 /* Return a simplified tree node for the truth-negation of ARG. This
3743 never alters ARG itself. We assume that ARG is an operation that
3744 returns a truth value (0 or 1).
3746 FIXME: one would think we would fold the result, but it causes
3747 problems with the dominator optimizer. */
3749 tree
3751 {
3752 tree tem;
3762 }
3764 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3765 operands are another bit-wise operation with a common input. If so,
3766 distribute the bit operations to save an operation and possibly two if
3767 constants are involved. For example, convert
3768 (A | B) & (A | C) into A | (B & C)
3769 Further simplification will occur if B and C are constants.
3771 If this optimization cannot be done, 0 will be returned. */
3773 static tree
3775 {
3776 tree common;
3786 {
3790 }
3792 {
3796 }
3798 {
3802 }
3804 {
3808 }
3809 else
3817 }
3819 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3820 with code CODE. This optimization is unsafe. */
3821 static tree
3823 {
3827 /* (A / C) +- (B / C) -> (A +- B) / C. */
3837 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3842 {
3854 }
3857 }
3858 \f
3859 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3860 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3862 static tree
3865 {
3869 {
3876 }
3890 }
3892 /* Optimize a bit-field compare.
3894 There are two cases: First is a compare against a constant and the
3895 second is a comparison of two items where the fields are at the same
3896 bit position relative to the start of a chunk (byte, halfword, word)
3897 large enough to contain it. In these cases we can avoid the shift
3898 implicit in bitfield extractions.
3900 For constants, we emit a compare of the shifted constant with the
3901 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3902 compared. For two fields at the same position, we do the ANDs with the
3903 similar mask and compare the result of the ANDs.
3905 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3906 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3907 are the left and right operands of the comparison, respectively.
3909 If the optimization described above can be done, we return the resulting
3910 tree. Otherwise we return zero. */
3912 static tree
3915 {
3924 tree mask;
3925 tree offset;
3927 /* Get all the information about the extractions being done. If the bit size
3928 if the same as the size of the underlying object, we aren't doing an
3929 extraction at all and so can do nothing. We also don't want to
3930 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3931 then will no longer be able to replace it. */
3939 {
3940 /* If this is not a constant, we can only do something if bit positions,
3941 sizes, and signedness are the same. */
3949 }
3951 /* See if we can find a mode to refer to this field. We should be able to,
3952 but fail if we can't. */
3961 /* Set signed and unsigned types of the precision of this mode for the
3962 shifts below. */
3966 /* Compute the bit position and size for the new reference and our offset
3967 within it. If the new reference is the same size as the original, we
3968 won't optimize anything, so return zero. */
3978 /* Make the mask to be used against the extracted field. */
3985 /* If not comparing with constant, just rework the comparison
3986 and return. */
3990 unsigned_type,
3993 mask),
3996 unsigned_type,
3999 mask));
4001 /* Otherwise, we are handling the constant case. See if the constant is too
4002 big for the field. Warn and return a tree of for 0 (false) if so. We do
4003 this not only for its own sake, but to avoid having to test for this
4004 error case below. If we didn't, we might generate wrong code.
4006 For unsigned fields, the constant shifted right by the field length should
4007 be all zero. For signed fields, the high-order bits should agree with
4008 the sign bit. */
4011 {
4015 {
4019 }
4020 }
4021 else
4022 {
4026 {
4030 }
4031 }
4033 /* Single-bit compares should always be against zero. */
4035 {
4038 }
4040 /* Make a new bitfield reference, shift the constant over the
4041 appropriate number of bits and mask it with the computed mask
4042 (in case this was a signed field). If we changed it, make a new one. */
4045 {
4048 }
4058 rhs);
4059 }
4060 \f
4061 /* Subroutine for fold_truthop: decode a field reference.
4063 If EXP is a comparison reference, we return the innermost reference.
4065 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4066 set to the starting bit number.
4068 If the innermost field can be completely contained in a mode-sized
4069 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4071 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4072 otherwise it is not changed.
4074 *PUNSIGNEDP is set to the signedness of the field.
4076 *PMASK is set to the mask used. This is either contained in a
4077 BIT_AND_EXPR or derived from the width of the field.
4079 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4081 Return 0 if this is not a component reference or is one that we can't
4082 do anything with. */
4084 static tree
4089 {
4093 tree unsigned_type;
4096 /* All the optimizations using this function assume integer fields.
4097 There are problems with FP fields since the type_for_size call
4098 below can fail for, e.g., XFmode. */
4102 /* We are interested in the bare arrangement of bits, so strip everything
4103 that doesn't affect the machine mode. However, record the type of the
4104 outermost expression if it may matter below. */
4111 {
4117 }
4126 /* If the number of bits in the reference is the same as the bitsize of
4127 the outer type, then the outer type gives the signedness. Otherwise
4128 (in case of a small bitfield) the signedness is unchanged. */
4132 /* Compute the mask to access the bitfield. */
4141 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4149 }
4151 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4152 bit positions. */
4154 static int
4156 {
4159 tree tmask;
4163 return
4170 }
4172 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4173 represents the sign bit of EXP's type. If EXP represents a sign
4174 or zero extension, also test VAL against the unextended type.
4175 The return value is the (sub)expression whose sign bit is VAL,
4176 or NULL_TREE otherwise. */
4178 static tree
4180 {
4184 tree t;
4186 /* Tree EXP must have an integral type. */
4191 /* Tree VAL must be an integer constant. */
4198 {
4205 }
4206 else
4207 {
4214 }
4216 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4217 treat VAL as if it were unsigned. */
4222 /* Handle extension from a narrower type. */
4228 }
4230 /* Subroutine for fold_truthop: determine if an operand is simple enough
4231 to be evaluated unconditionally. */
4233 static int
4235 {
4236 /* Strip any conversions that don't change the machine mode. */
4245 /* Don't regard global variables as simple. They may be
4246 allocated in ways unknown to the compiler (shared memory,
4247 #pragma weak, etc). */
4250 /* Loading a static variable is unduly expensive, but global
4251 registers aren't expensive. */
4253 }
4254 \f
4255 /* The following functions are subroutines to fold_range_test and allow it to
4256 try to change a logical combination of comparisons into a range test.
4258 For example, both
4259 X == 2 || X == 3 || X == 4 || X == 5
4260 and
4261 X >= 2 && X <= 5
4262 are converted to
4263 (unsigned) (X - 2) <= 3
4265 We describe each set of comparisons as being either inside or outside
4266 a range, using a variable named like IN_P, and then describe the
4267 range with a lower and upper bound. If one of the bounds is omitted,
4268 it represents either the highest or lowest value of the type.
4270 In the comments below, we represent a range by two numbers in brackets
4271 preceded by a "+" to designate being inside that range, or a "-" to
4272 designate being outside that range, so the condition can be inverted by
4273 flipping the prefix. An omitted bound is represented by a "-". For
4274 example, "- [-, 10]" means being outside the range starting at the lowest
4275 possible value and ending at 10, in other words, being greater than 10.
4276 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4277 always false.
4279 We set up things so that the missing bounds are handled in a consistent
4280 manner so neither a missing bound nor "true" and "false" need to be
4281 handled using a special case. */
4283 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4284 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4285 and UPPER1_P are nonzero if the respective argument is an upper bound
4286 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4287 must be specified for a comparison. ARG1 will be converted to ARG0's
4288 type if both are specified. */
4290 static tree
4293 {
4294 tree tem;
4298 /* If neither arg represents infinity, do the normal operation.
4299 Else, if not a comparison, return infinity. Else handle the special
4300 comparison rules. Note that most of the cases below won't occur, but
4301 are handled for consistency. */
4304 {
4309 }
4314 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4315 for neither. In real maths, we cannot assume open ended ranges are
4316 the same. But, this is computer arithmetic, where numbers are finite.
4317 We can therefore make the transformation of any unbounded range with
4318 the value Z, Z being greater than any representable number. This permits
4319 us to treat unbounded ranges as equal. */
4323 {
4344 }
4347 }
4348 \f
4349 /* Given EXP, a logical expression, set the range it is testing into
4350 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4351 actually being tested. *PLOW and *PHIGH will be made of the same
4352 type as the returned expression. If EXP is not a comparison, we
4353 will most likely not be returning a useful value and range. Set
4354 *STRICT_OVERFLOW_P to true if the return value is only valid
4355 because signed overflow is undefined; otherwise, do not change
4356 *STRICT_OVERFLOW_P. */
4358 static tree
4361 {
4368 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4369 and see if we can refine the range. Some of the cases below may not
4370 happen, but it doesn't seem worth worrying about this. We "continue"
4371 the outer loop when we've changed something; otherwise we "break"
4372 the switch, which will "break" the while. */
4378 {
4383 {
4395 }
4398 {
4405 /* We can only do something if the range is testing for zero
4406 and if the second operand is an integer constant. Note that
4407 saying something is "in" the range we make is done by
4408 complementing IN_P since it will set in the initial case of
4409 being not equal to zero; "out" is leaving it alone. */
4416 {
4437 }
4439 /* If this is an unsigned comparison, we also know that EXP is
4440 greater than or equal to zero. We base the range tests we make
4441 on that fact, so we record it here so we can parse existing
4442 range tests. We test arg0_type since often the return type
4443 of, e.g. EQ_EXPR, is boolean. */
4445 {
4449 NULL_TREE))
4454 /* If the high bound is missing, but we have a nonzero low
4455 bound, reverse the range so it goes from zero to the low bound
4456 minus 1. */
4458 {
4463 }
4464 }
4470 /* (-x) IN [a,b] -> x in [-b, -a] */
4482 /* ~ X -> -X - 1 */
4491 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4492 move a constant to the other side. */
4497 /* If EXP is signed, any overflow in the computation is undefined,
4498 so we don't worry about it so long as our computations on
4499 the bounds don't overflow. For unsigned, overflow is defined
4500 and this is exactly the right thing. */
4512 /* Check for an unsigned range which has wrapped around the maximum
4513 value thus making n_high < n_low, and normalize it. */
4515 {
4521 /* If the range is of the form +/- [ x+1, x ], we won't
4522 be able to normalize it. But then, it represents the
4523 whole range or the empty set, so make it
4524 +/- [ -, - ]. */
4528 else
4530 }
4531 else
4555 /* If we're converting arg0 from an unsigned type, to exp,
4556 a signed type, we will be doing the comparison as unsigned.
4557 The tests above have already verified that LOW and HIGH
4558 are both positive.
4560 So we have to ensure that we will handle large unsigned
4561 values the same way that the current signed bounds treat
4562 negative values. */
4565 {
4566 tree high_positive;
4567 tree equiv_type;
4568 /* For fixed-point modes, we need to pass the saturating flag
4569 as the 2nd parameter. */
4574 else
4578 /* A range without an upper bound is, naturally, unbounded.
4579 Since convert would have cropped a very large value, use
4580 the max value for the destination type. */
4581 high_positive
4588 high_positive),
4591 /* If the low bound is specified, "and" the range with the
4592 range for which the original unsigned value will be
4593 positive. */
4595 {
4599 integer_zero_node),
4600 high_positive))
4604 }
4605 else
4606 {
4607 /* Otherwise, "or" the range with the range of the input
4608 that will be interpreted as negative. */
4612 integer_zero_node),
4613 high_positive))
4617 }
4618 }
4626 }
4629 }
4631 /* If EXP is a constant, we can evaluate whether this is true or false. */
4633 {
4640 }
4644 }
4645 \f
4646 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4647 type, TYPE, return an expression to test if EXP is in (or out of, depending
4648 on IN_P) the range. Return 0 if the test couldn't be created. */
4650 static tree
4652 {
4654 tree value;
4656 #ifdef HAVE_canonicalize_funcptr_for_compare
4657 /* Disable this optimization for function pointer expressions
4658 on targets that require function pointer canonicalization. */
4663 #endif
4666 {
4672 }
4690 {
4692 {
4696 }
4698 }
4700 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4702 {
4704 HOST_WIDE_INT hi;
4709 {
4712 }
4713 else
4714 {
4717 }
4720 {
4722 {
4725 etype
4727 else
4730 }
4733 }
4734 }
4736 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4737 This requires wrap-around arithmetics for the type of the expression. */
4739 {
4741 /* There is no requirement that LOW be within the range of ETYPE
4742 if the latter is a subtype. It must, however, be within the base
4743 type of ETYPE. So be sure we do the subtraction in that type. */
4756 }
4758 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4761 {
4764 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4765 for the type in question, as we rely on this here. */
4775 else
4777 }
4787 {
4789 {
4795 }
4797 }
4805 }
4806 \f
4807 /* Return the predecessor of VAL in its type, handling the infinite case. */
4809 static tree
4811 {
4817 else
4819 }
4821 /* Return the successor of VAL in its type, handling the infinite case. */
4823 static tree
4825 {
4831 else
4833 }
4835 /* Given two ranges, see if we can merge them into one. Return 1 if we
4836 can, 0 if we can't. Set the output range into the specified parameters. */
4838 static int
4841 {
4845 tree tem;
4855 /* Make range 0 be the range that starts first, or ends last if they
4856 start at the same value. Swap them if it isn't. */
4859 || (lowequal
4862 {
4866 }
4868 /* Now flag two cases, whether the ranges are disjoint or whether the
4869 second range is totally subsumed in the first. Note that the tests
4870 below are simplified by the ones above. */
4876 /* We now have four cases, depending on whether we are including or
4877 excluding the two ranges. */
4879 {
4880 /* If they don't overlap, the result is false. If the second range
4881 is a subset it is the result. Otherwise, the range is from the start
4882 of the second to the end of the first. */
4887 else
4889 }
4892 {
4893 /* If they don't overlap, the result is the first range. If they are
4894 equal, the result is false. If the second range is a subset of the
4895 first, and the ranges begin at the same place, we go from just after
4896 the end of the second range to the end of the first. If the second
4897 range is not a subset of the first, or if it is a subset and both
4898 ranges end at the same place, the range starts at the start of the
4899 first range and ends just before the second range.
4900 Otherwise, we can't describe this as a single range. */
4906 {
4911 {
4912 /* We are in the weird situation where high0 > high1 but
4913 high1 has no successor. Punt. */
4915 }
4916 }
4918 {
4923 {
4924 /* low0 < low1 but low1 has no predecessor. Punt. */
4926 }
4927 }
4928 else
4930 }
4933 {
4934 /* If they don't overlap, the result is the second range. If the second
4935 is a subset of the first, the result is false. Otherwise,
4936 the range starts just after the first range and ends at the
4937 end of the second. */
4942 else
4943 {
4948 {
4949 /* high1 > high0 but high0 has no successor. Punt. */
4951 }
4952 }
4953 }
4955 else
4956 {
4957 /* The case where we are excluding both ranges. Here the complex case
4958 is if they don't overlap. In that case, the only time we have a
4959 range is if they are adjacent. If the second is a subset of the
4960 first, the result is the first. Otherwise, the range to exclude
4961 starts at the beginning of the first range and ends at the end of the
4962 second. */
4964 {
4969 else
4970 {
4971 /* Canonicalize - [min, x] into - [-, x]. */
4974 {
4979 /* FALLTHROUGH */
4992 }
4994 /* Canonicalize - [x, max] into - [x, -]. */
4997 {
5002 /* FALLTHROUGH */
5017 }
5019 /* The ranges might be also adjacent between the maximum and
5020 minimum values of the given type. For
5021 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5022 return + [x + 1, y - 1]. */
5024 {
5031 }
5032 else
5034 }
5035 }
5038 else
5040 }
5044 }
5045 \f
5047 /* Subroutine of fold, looking inside expressions of the form
5048 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5049 of the COND_EXPR. This function is being used also to optimize
5050 A op B ? C : A, by reversing the comparison first.
5052 Return a folded expression whose code is not a COND_EXPR
5053 anymore, or NULL_TREE if no folding opportunity is found. */
5055 static tree
5057 {
5062 tree tem;
5067 /* If we have A op 0 ? A : -A, consider applying the following
5068 transformations:
5070 A == 0? A : -A same as -A
5071 A != 0? A : -A same as A
5072 A >= 0? A : -A same as abs (A)
5073 A > 0? A : -A same as abs (A)
5074 A <= 0? A : -A same as -abs (A)
5075 A < 0? A : -A same as -abs (A)
5077 None of these transformations work for modes with signed
5078 zeros. If A is +/-0, the first two transformations will
5079 change the sign of the result (from +0 to -0, or vice
5080 versa). The last four will fix the sign of the result,
5081 even though the original expressions could be positive or
5082 negative, depending on the sign of A.
5084 Note that all these transformations are correct if A is
5085 NaN, since the two alternatives (A and -A) are also NaNs. */
5092 /* In the case that A is of the form X-Y, '-A' (arg2) may
5093 have already been folded to Y-X, check for that. */
5101 {
5113 /* Fall through. */
5135 }
5137 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5138 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5139 both transformations are correct when A is NaN: A != 0
5140 is then true, and A == 0 is false. */
5144 {
5149 }
5151 /* Try some transformations of A op B ? A : B.
5153 A == B? A : B same as B
5154 A != B? A : B same as A
5155 A >= B? A : B same as max (A, B)
5156 A > B? A : B same as max (B, A)
5157 A <= B? A : B same as min (A, B)
5158 A < B? A : B same as min (B, A)
5160 As above, these transformations don't work in the presence
5161 of signed zeros. For example, if A and B are zeros of
5162 opposite sign, the first two transformations will change
5163 the sign of the result. In the last four, the original
5164 expressions give different results for (A=+0, B=-0) and
5165 (A=-0, B=+0), but the transformed expressions do not.
5167 The first two transformations are correct if either A or B
5168 is a NaN. In the first transformation, the condition will
5169 be false, and B will indeed be chosen. In the case of the
5170 second transformation, the condition A != B will be true,
5171 and A will be chosen.
5173 The conversions to max() and min() are not correct if B is
5174 a number and A is not. The conditions in the original
5175 expressions will be false, so all four give B. The min()
5176 and max() versions would give a NaN instead. */
5179 /* Avoid these transformations if the COND_EXPR may be used
5180 as an lvalue in the C++ front-end. PR c++/19199. */
5181 && (in_gimple_form
5186 {
5191 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5193 {
5197 }
5200 {
5209 /* In C++ a ?: expression can be an lvalue, so put the
5210 operand which will be used if they are equal first
5211 so that we can convert this back to the
5212 corresponding COND_EXPR. */
5214 {
5221 }
5228 {
5235 }
5248 }
5249 }
5251 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5252 we might still be able to simplify this. For example,
5253 if C1 is one less or one more than C2, this might have started
5254 out as a MIN or MAX and been transformed by this function.
5255 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5261 {
5263 /* We can replace A with C1 in this case. */
5268 /* If C1 is C2 + 1, this is min(A, C2). */
5270 OEP_ONLY_CONST)
5274 OEP_ONLY_CONST))
5276 type,
5278 arg2));
5282 /* If C1 is C2 - 1, this is min(A, C2). */
5284 OEP_ONLY_CONST)
5288 OEP_ONLY_CONST))
5290 type,
5292 arg2));
5296 /* If C1 is C2 - 1, this is max(A, C2). */
5298 OEP_ONLY_CONST)
5302 OEP_ONLY_CONST))
5304 type,
5306 arg2));
5310 /* If C1 is C2 + 1, this is max(A, C2). */
5312 OEP_ONLY_CONST)
5316 OEP_ONLY_CONST))
5318 type,
5320 arg2));
5326 }
5329 }
5332 \f
5333 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5334 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5335 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5336 false) >= 2)
5337 #endif
5339 /* EXP is some logical combination of boolean tests. See if we can
5340 merge it into some range test. Return the new tree if so. */
5342 static tree
5344 {
5352 tree tem;
5356 /* If this is an OR operation, invert both sides; we will invert
5357 again at the end. */
5361 /* If both expressions are the same, if we can merge the ranges, and we
5362 can build the range test, return it or it inverted. If one of the
5363 ranges is always true or always false, consider it to be the same
5364 expression as the other. */
5372 {
5376 }
5378 /* On machines where the branch cost is expensive, if this is a
5379 short-circuited branch and the underlying object on both sides
5380 is the same, make a non-short-circuit operation. */
5386 {
5387 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5388 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5389 which cases we can't do this. */
5397 {
5406 {
5409 WARN_STRICT_OVERFLOW_COMPARISON);
5413 }
5414 }
5415 }
5418 }
5419 \f
5420 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5421 bit value. Arrange things so the extra bits will be set to zero if and
5422 only if C is signed-extended to its full width. If MASK is nonzero,
5423 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5425 static tree
5427 {
5430 tree temp;
5435 /* We work by getting just the sign bit into the low-order bit, then
5436 into the high-order bit, then sign-extend. We then XOR that value
5437 with C. */
5441 /* We must use a signed type in order to get an arithmetic right shift.
5442 However, we must also avoid introducing accidental overflows, so that
5443 a subsequent call to integer_zerop will work. Hence we must
5444 do the type conversion here. At this point, the constant is either
5445 zero or one, and the conversion to a signed type can never overflow.
5446 We could get an overflow if this conversion is done anywhere else. */
5455 /* If necessary, convert the type back to match the type of C. */
5460 }
5461 \f
5462 /* Find ways of folding logical expressions of LHS and RHS:
5463 Try to merge two comparisons to the same innermost item.
5464 Look for range tests like "ch >= '0' && ch <= '9'".
5465 Look for combinations of simple terms on machines with expensive branches
5466 and evaluate the RHS unconditionally.
5468 For example, if we have p->a == 2 && p->b == 4 and we can make an
5469 object large enough to span both A and B, we can do this with a comparison
5470 against the object ANDed with the a mask.
5472 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5473 operations to do this with one comparison.
5475 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5476 function and the one above.
5478 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5479 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5481 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5482 two operands.
5484 We return the simplified tree or 0 if no optimization is possible. */
5486 static tree
5488 {
5489 /* If this is the "or" of two comparisons, we can do something if
5490 the comparisons are NE_EXPR. If this is the "and", we can do something
5491 if the comparisons are EQ_EXPR. I.e.,
5492 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5494 WANTED_CODE is this operation code. For single bit fields, we can
5495 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5496 comparison for one-bit fields. */
5518 /* Start by getting the comparison codes. Fail if anything is volatile.
5519 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5520 it were surrounded with a NE_EXPR. */
5529 {
5533 }
5536 {
5540 }
5551 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5554 {
5555 tree result;
5558 {
5563 }
5566 {
5572 }
5573 }
5578 /* If the RHS can be evaluated unconditionally and its operands are
5579 simple, it wins to evaluate the RHS unconditionally on machines
5580 with expensive branches. In this case, this isn't a comparison
5581 that can be merged. Avoid doing this if the RHS is a floating-point
5582 comparison since those can trap. */
5589 {
5590 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5601 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5613 {
5617 }
5618 }
5620 /* See if the comparisons can be merged. Then get all the parameters for
5621 each side. */
5645 /* It must be true that the inner operation on the lhs of each
5646 comparison must be the same if we are to be able to do anything.
5647 Then see if we have constants. If not, the same must be true for
5648 the rhs's. */
5659 else
5662 /* If either comparison code is not correct for our logical operation,
5663 fail. However, we can convert a one-bit comparison against zero into
5664 the opposite comparison against that bit being set in the field. */
5668 {
5670 {
5671 /* Make the left operand unsigned, since we are only interested
5672 in the value of one bit. Otherwise we are doing the wrong
5673 thing below. */
5676 }
5677 else
5679 }
5681 /* This is analogous to the code for l_const above. */
5683 {
5685 {
5688 }
5689 else
5691 }
5693 /* See if we can find a mode that contains both fields being compared on
5694 the left. If we can't, fail. Otherwise, update all constants and masks
5695 to be relative to a field of that size. */
5700 volatilep);
5710 {
5713 }
5721 {
5729 {
5733 }
5734 }
5736 {
5744 {
5748 }
5749 }
5751 /* If the right sides are not constant, do the same for it. Also,
5752 disallow this optimization if a size or signedness mismatch occurs
5753 between the left and right sides. */
5755 {
5758 /* Make sure the two fields on the right
5759 correspond to the left without being swapped. */
5767 volatilep);
5777 {
5780 }
5787 /* Make a mask that corresponds to both fields being compared.
5788 Do this for both items being compared. If the operands are the
5789 same size and the bits being compared are in the same position
5790 then we can do this by masking both and comparing the masked
5791 results. */
5795 {
5807 }
5809 /* There is still another way we can do something: If both pairs of
5810 fields being compared are adjacent, we may be able to make a wider
5811 field containing them both.
5813 Note that we still must mask the lhs/rhs expressions. Furthermore,
5814 the mask must be shifted to account for the shift done by
5815 make_bit_field_ref. */
5820 {
5821 tree type;
5833 /* Convert to the smaller type before masking out unwanted bits. */
5836 {
5838 {
5842 }
5844 {
5848 }
5849 }
5858 }
5861 }
5863 /* Handle the case of comparisons with constants. If there is something in
5864 common between the masks, those bits of the constants must be the same.
5865 If not, the condition is always false. Test for this to avoid generating
5866 incorrect code below. */
5871 {
5873 {
5876 }
5877 else
5878 {
5881 }
5882 }
5884 /* Construct the expression we will return. First get the component
5885 reference we will make. Unless the mask is all ones the width of
5886 that field, perform the mask operation. Then compare with the
5887 merged constant. */
5897 }
5898 \f
5899 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5900 constant. */
5902 static tree
5904 {
5907 tree comp_const;
5908 tree minmax_const;
5910 tree inner;
5921 /* If something does not permit us to optimize, return the original tree. */
5929 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5930 and GT_EXPR, doing the rest with recursive calls using logical
5931 simplifications. */
5933 {
5935 {
5941 }
5944 return
5946 optimize_minmax_comparison
5948 optimize_minmax_comparison
5953 /* MAX (X, 0) == 0 -> X <= 0 */
5957 /* MAX (X, 0) == 5 -> X == 5 */
5961 /* MAX (X, 0) == -1 -> false */
5965 /* MIN (X, 0) == 0 -> X >= 0 */
5969 /* MIN (X, 0) == 5 -> false */
5972 else
5973 /* MIN (X, 0) == -1 -> X == -1 */
5978 /* MAX (X, 0) > 0 -> X > 0
5979 MAX (X, 0) > 5 -> X > 5 */
5983 /* MAX (X, 0) > -1 -> true */
5987 /* MIN (X, 0) > 0 -> false
5988 MIN (X, 0) > 5 -> false */
5991 else
5992 /* MIN (X, 0) > -1 -> X > -1 */
5997 }
5998 }
5999 \f
6000 /* T is an integer expression that is being multiplied, divided, or taken a
6001 modulus (CODE says which and what kind of divide or modulus) by a
6002 constant C. See if we can eliminate that operation by folding it with
6003 other operations already in T. WIDE_TYPE, if non-null, is a type that
6004 should be used for the computation if wider than our type.
6006 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6007 (X * 2) + (Y * 4). We must, however, be assured that either the original
6008 expression would not overflow or that overflow is undefined for the type
6009 in the language in question.
6011 If we return a non-null expression, it is an equivalent form of the
6012 original computation, but need not be in the original type.
6014 We set *STRICT_OVERFLOW_P to true if the return values depends on
6015 signed overflow being undefined. Otherwise we do not change
6016 *STRICT_OVERFLOW_P. */
6018 static tree
6021 {
6022 /* To avoid exponential search depth, refuse to allow recursion past
6023 three levels. Beyond that (1) it's highly unlikely that we'll find
6024 something interesting and (2) we've probably processed it before
6025 when we built the inner expression. */
6028 tree ret;
6033 depth++;
6035 depth--;
6038 }
6040 static tree
6043 {
6054 /* Don't deal with constants of zero here; they confuse the code below. */
6064 /* Note that we need not handle conditional operations here since fold
6065 already handles those cases. So just do arithmetic here. */
6067 {
6069 /* For a constant, we can always simplify if we are a multiply
6070 or (for divide and modulus) if it is a multiple of our constant. */
6078 /* If op0 is an expression ... */
6084 /* ... and has wrapping overflow, and its type is smaller
6085 than ctype, then we cannot pass through as widening. */
6091 /* ... or this is a truncation (t is narrower than op0),
6092 then we cannot pass through this narrowing. */
6095 /* ... or signedness changes for division or modulus,
6096 then we cannot pass through this conversion. */
6100 /* ... or has undefined overflow while the converted to
6101 type has not, we cannot do the operation in the inner type
6102 as that would introduce undefined overflow. */
6107 /* Pass the constant down and see if we can make a simplification. If
6108 we can, replace this expression with the inner simplification for
6109 possible later conversion to our or some other type. */
6114 code == MULT_EXPR
6116 strict_overflow_p))))
6121 /* If widening the type changes it from signed to unsigned, then we
6122 must avoid building ABS_EXPR itself as unsigned. */
6124 {
6128 {
6131 }
6133 }
6134 /* If the constant is negative, we cannot simplify this. */
6137 /* FALLTHROUGH */
6145 /* If widening the type changes the signedness, then we can't perform
6146 this optimization as that changes the result. */
6150 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6156 {
6163 }
6167 /* If the second operand is constant, this is a multiplication
6168 or floor division, by a power of two, so we can treat it that
6169 way unless the multiplier or divisor overflows. Signed
6170 left-shift overflow is implementation-defined rather than
6171 undefined in C90, so do not convert signed left shift into
6172 multiplication. */
6175 /* const_binop may not detect overflow correctly,
6176 so check for it explicitly here. */
6181 size_one_node,
6191 /* See if we can eliminate the operation on both sides. If we can, we
6192 can return a new PLUS or MINUS. If we can't, the only remaining
6193 cases where we can do anything are if the second operand is a
6194 constant. */
6200 /* If not multiplication, we can only do this if both operands
6201 are divisible by c. */
6204 {
6209 }
6211 /* If this was a subtraction, negate OP1 and set it to be an addition.
6212 This simplifies the logic below. */
6219 /* If either OP1 or C are negative, this optimization is not safe for
6220 some of the division and remainder types while for others we need
6221 to change the code. */
6223 {
6231 }
6233 /* If it's a multiply or a division/modulus operation of a multiple
6234 of our constant, do the operation and verify it doesn't overflow. */
6237 {
6240 /* We allow the constant to overflow with wrapping semantics. */
6244 }
6245 else
6248 /* If we have an unsigned type is not a sizetype, we cannot widen
6249 the operation since it will change the result if the original
6250 computation overflowed. */
6256 /* If we were able to eliminate our operation from the first side,
6257 apply our operation to the second side and reform the PLUS. */
6261 /* The last case is if we are a multiply. In that case, we can
6262 apply the distributive law to commute the multiply and addition
6263 if the multiplication of the constants doesn't overflow. */
6269 op1);
6274 /* We have a special case here if we are doing something like
6275 (C * 8) % 4 since we know that's zero. */
6278 /* If the multiplication can overflow we cannot optimize this.
6279 ??? Until we can properly mark individual operations as
6280 not overflowing we need to treat sizetype special here as
6281 stor-layout relies on this opimization to make
6282 DECL_FIELD_BIT_OFFSET always a constant. */
6288 {
6291 }
6293 /* ... fall through ... */
6297 /* If we can extract our operation from the LHS, do so and return a
6298 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6299 do something only if the second operand is a constant. */
6313 /* If these are the same operation types, we can associate them
6314 assuming no overflow. */
6326 /* If these operations "cancel" each other, we have the main
6327 optimizations of this pass, which occur when either constant is a
6328 multiple of the other, in which case we replace this with either an
6329 operation or CODE or TCODE.
6331 If we have an unsigned type that is not a sizetype, we cannot do
6332 this since it will change the result if the original computation
6333 overflowed. */
6341 {
6343 {
6350 }
6352 {
6359 }
6360 }
6365 }
6368 }
6369 \f
6370 /* Return a node which has the indicated constant VALUE (either 0 or
6371 1), and is of the indicated TYPE. */
6373 tree
6375 {
6380 else
6382 }
6385 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6386 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6387 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6388 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6389 COND is the first argument to CODE; otherwise (as in the example
6390 given here), it is the second argument. TYPE is the type of the
6391 original expression. Return NULL_TREE if no simplification is
6392 possible. */
6394 static tree
6398 {
6405 /* This transformation is only worthwhile if we don't have to wrap
6406 arg in a SAVE_EXPR, and the operation can be simplified on at least
6407 one of the branches once its pushed inside the COND_EXPR. */
6412 {
6416 /* If this operand throws an expression, then it does not make
6417 sense to try to perform a logical or arithmetic operation
6418 involving it. */
6423 }
6424 else
6425 {
6430 }
6434 {
6438 else
6440 }
6442 {
6446 else
6448 }
6452 }
6454 \f
6455 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6457 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6458 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6459 ADDEND is the same as X.
6461 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6462 and finite. The problematic cases are when X is zero, and its mode
6463 has signed zeros. In the case of rounding towards -infinity,
6464 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6465 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6467 bool
6469 {
6473 /* Don't allow the fold with -fsignaling-nans. */
6477 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6481 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6486 /* The mode has signed zeros, and we have to honor their sign.
6487 In this situation, there is only one case we can return true for.
6488 X - 0 is the same as X unless rounding towards -infinity is
6489 supported. */
6491 }
6493 /* Subroutine of fold() that checks comparisons of built-in math
6494 functions against real constants.
6496 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6497 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6498 is the type of the result and ARG0 and ARG1 are the operands of the
6499 comparison. ARG1 must be a TREE_REAL_CST.
6501 The function returns the constant folded tree if a simplification
6502 can be made, and NULL_TREE otherwise. */
6504 static tree
6507 {
6508 REAL_VALUE_TYPE c;
6511 {
6517 {
6518 /* sqrt(x) < y is always false, if y is negative. */
6522 /* sqrt(x) > y is always true, if y is negative and we
6523 don't care about NaNs, i.e. negative values of x. */
6527 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6530 }
6532 {
6533 REAL_VALUE_TYPE c2;
6539 {
6540 /* sqrt(x) > y is x == +Inf, when y is very large. */
6545 /* sqrt(x) > y is always false, when y is very large
6546 and we don't care about infinities. */
6548 }
6550 /* sqrt(x) > c is the same as x > c*c. */
6553 }
6555 {
6556 REAL_VALUE_TYPE c2;
6562 {
6563 /* sqrt(x) < y is always true, when y is a very large
6564 value and we don't care about NaNs or Infinities. */
6568 /* sqrt(x) < y is x != +Inf when y is very large and we
6569 don't care about NaNs. */
6574 /* sqrt(x) < y is x >= 0 when y is very large and we
6575 don't care about Infinities. */
6580 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6589 dconst0)),
6592 c2)));
6593 }
6595 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6600 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6603 {
6608 dconst0)),
6611 c2)));
6612 }
6613 }
6614 }
6617 }
6619 /* Subroutine of fold() that optimizes comparisons against Infinities,
6620 either +Inf or -Inf.
6622 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6623 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6624 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6626 The function returns the constant folded tree if a simplification
6627 can be made, and NULL_TREE otherwise. */
6629 static tree
6631 {
6633 REAL_VALUE_TYPE max;
6634 tree temp;
6639 /* For negative infinity swap the sense of the comparison. */
6645 {
6647 /* x > +Inf is always false, if with ignore sNANs. */
6653 /* x <= +Inf is always true, if we don't case about NaNs. */
6657 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6660 {
6663 }
6668 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6674 /* x < +Inf is always equal to x <= DBL_MAX. */
6680 /* x != +Inf is always equal to !(x > DBL_MAX). */
6692 }
6695 }
6697 /* Subroutine of fold() that optimizes comparisons of a division by
6698 a nonzero integer constant against an integer constant, i.e.
6699 X/C1 op C2.
6701 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6702 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6703 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6705 The function returns the constant folded tree if a simplification
6706 can be made, and NULL_TREE otherwise. */
6708 static tree
6710 {
6715 HOST_WIDE_INT hpart;
6720 /* We have to do this the hard way to detect unsigned overflow.
6721 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6732 {
6737 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6745 }
6747 {
6751 {
6770 }
6771 }
6772 else
6773 {
6774 /* A negative divisor reverses the relational operators. */
6780 {
6799 }
6800 }
6803 {
6824 {
6827 }
6832 {
6835 }
6840 {
6843 }
6848 {
6851 }
6856 }
6859 }
6862 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6863 equality/inequality test, then return a simplified form of the test
6864 using a sign testing. Otherwise return NULL. TYPE is the desired
6865 result type. */
6867 static tree
6869 tree result_type)
6870 {
6871 /* If this is testing a single bit, we can optimize the test. */
6875 {
6876 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6877 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6881 /* This is only a win if casting to a signed type is cheap,
6882 i.e. when arg00's type is not a partial mode. */
6885 {
6890 }
6891 }
6894 }
6896 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6897 equality/inequality test, then return a simplified form of
6898 the test using shifts and logical operations. Otherwise return
6899 NULL. TYPE is the desired result type. */
6901 tree
6903 tree result_type)
6904 {
6905 /* If this is testing a single bit, we can optimize the test. */
6909 {
6918 /* First, see if we can fold the single bit test into a sign-bit
6919 test. */
6921 result_type);
6925 /* Otherwise we have (A & C) != 0 where C is a single bit,
6926 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6927 Similarly for (A & C) == 0. */
6929 /* If INNER is a right shift of a constant and it plus BITNUM does
6930 not overflow, adjust BITNUM and INNER. */
6937 {
6940 }
6942 /* If we are going to be able to omit the AND below, we must do our
6943 operations as unsigned. If we must use the AND, we have a choice.
6944 Normally unsigned is faster, but for some machines signed is. */
6945 #ifdef LOAD_EXTEND_OP
6948 #else
6950 #endif
6966 /* Put the AND last so it can combine with more things. */
6969 /* Make sure to return the proper type. */
6973 }
6975 }
6977 /* Check whether we are allowed to reorder operands arg0 and arg1,
6978 such that the evaluation of arg1 occurs before arg0. */
6980 static bool
6982 {
6989 }
6991 /* Test whether it is preferable two swap two operands, ARG0 and
6992 ARG1, for example because ARG0 is an integer constant and ARG1
6993 isn't. If REORDER is true, only recommend swapping if we can
6994 evaluate the operands in reverse order. */
6996 bool
6998 {
7034 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7035 for commutative and comparison operators. Ensuring a canonical
7036 form allows the optimizers to find additional redundancies without
7037 having to explicitly check for both orderings. */
7043 /* Put SSA_NAMEs last. */
7049 /* Put variables last. */
7056 }
7058 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7059 ARG0 is extended to a wider type. */
7061 static tree
7063 {
7065 tree arg1_unw;
7074 #ifdef HAVE_canonicalize_funcptr_for_compare
7075 /* Disable this optimization if we're casting a function pointer
7076 type on targets that require function pointer canonicalization. */
7081 #endif
7088 /* If possible, express the comparison in the shorter mode. */
7108 /* If we are comparing with the integer that does not fit into the range
7109 of the shorter type, the result is known. */
7120 {
7147 }
7150 }
7152 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7153 ARG0 just the signedness is changed. */
7155 static tree
7158 {
7159 tree arg0_inner;
7169 #ifdef HAVE_canonicalize_funcptr_for_compare
7170 /* Disable this optimization if we're casting a function pointer
7171 type on targets that require function pointer canonicalization. */
7176 #endif
7181 /* If the conversion is from an integral subtype to its basetype
7182 leave it alone. */
7201 else
7205 }
7207 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7208 step of the array. Reconstructs s and delta in the case of s * delta
7209 being an integer constant (and thus already folded).
7210 ADDR is the address. MULT is the multiplicative expression.
7211 If the function succeeds, the new address expression is returned. Otherwise
7212 NULL_TREE is returned. */
7214 static tree
7216 {
7220 tree itype;
7223 /* Strip the nops that might be added when converting op1 to sizetype. */
7226 /* Canonicalize op1 into a possibly non-constant delta
7227 and an INTEGER_CST s. */
7229 {
7236 {
7239 }
7241 {
7244 }
7245 else
7247 }
7249 {
7252 }
7253 else
7254 {
7255 /* Simulate we are delta * 1. */
7258 }
7261 {
7263 {
7264 /* Remember if this was a multi-dimensional array. */
7277 {
7280 }
7281 else
7282 {
7283 /* Try if delta is a multiple of step. */
7288 }
7290 /* Only fold here if we can verify we do not overflow one
7291 dimension of a multi-dimensional array. */
7293 {
7294 tree tmp;
7310 }
7313 }
7314 else
7319 }
7321 /* We found the suitable array reference. So copy everything up to it,
7322 and replace the index. */
7329 {
7333 }
7341 }
7344 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7345 means A >= Y && A != MAX, but in this case we know that
7346 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7348 static tree
7350 {
7357 else
7366 {
7369 }
7371 {
7374 }
7375 else
7382 {
7383 /* Convert the pointer types into integer before taking the difference. */
7387 }
7388 else
7395 }
7397 /* Fold a sum or difference of at least one multiplication.
7398 Returns the folded tree or NULL if no simplification could be made. */
7400 static tree
7402 {
7406 /* (A * C) +- (B * C) -> (A+-B) * C.
7407 (A * C) +- A -> A * (C+-1).
7408 We are most concerned about the case where C is a constant,
7409 but other combinations show up during loop reduction. Since
7410 it is not difficult, try all four possibilities. */
7413 {
7416 }
7418 {
7421 }
7422 else
7423 {
7424 /* We cannot generate constant 1 for fract. */
7429 }
7431 {
7434 }
7436 {
7438 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7439 the purpose of this canonicalization. */
7443 {
7446 }
7447 else
7449 }
7450 else
7451 {
7452 /* We cannot generate constant 1 for fract. */
7457 }
7469 /* No identical multiplicands; see if we can find a common
7470 power-of-two factor in non-power-of-two multiplies. This
7471 can help in multi-dimensional array access. */
7474 {
7477 tree maybe_same;
7481 /* Move min of absolute values to int11. */
7484 {
7489 }
7490 else
7494 {
7502 }
7503 }
7513 }
7515 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7516 specified by EXPR into the buffer PTR of length LEN bytes.
7517 Return the number of bytes placed in the buffer, or zero
7518 upon failure. */
7520 static int
7522 {
7533 {
7537 else
7542 {
7549 else
7551 }
7552 else
7555 }
7557 }
7560 /* Subroutine of native_encode_expr. Encode the REAL_CST
7561 specified by EXPR into the buffer PTR of length LEN bytes.
7562 Return the number of bytes placed in the buffer, or zero
7563 upon failure. */
7565 static int
7567 {
7573 /* There are always 32 bits in each long, no matter the size of
7574 the hosts long. We handle floating point representations with
7575 up to 192 bits. */
7586 {
7591 {
7598 else
7600 }
7601 else
7604 }
7606 }
7608 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7609 specified by EXPR into the buffer PTR of length LEN bytes.
7610 Return the number of bytes placed in the buffer, or zero
7611 upon failure. */
7613 static int
7615 {
7617 tree part;
7628 }
7631 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7632 specified by EXPR into the buffer PTR of length LEN bytes.
7633 Return the number of bytes placed in the buffer, or zero
7634 upon failure. */
7636 static int
7638 {
7648 {
7650 {
7653 }
7654 else
7658 {
7661 }
7662 else
7663 {
7667 }
7669 }
7671 }
7674 /* Subroutine of native_encode_expr. Encode the STRING_CST
7675 specified by EXPR into the buffer PTR of length LEN bytes.
7676 Return the number of bytes placed in the buffer, or zero
7677 upon failure. */
7679 static int
7681 {
7683 HOST_WIDE_INT total_bytes;
7694 {
7698 }
7699 else
7702 }
7705 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7706 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7707 buffer PTR of length LEN bytes. Return the number of bytes
7708 placed in the buffer, or zero upon failure. */
7710 int
7712 {
7714 {
7732 }
7733 }
7736 /* Subroutine of native_interpret_expr. Interpret the contents of
7737 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7738 If the buffer cannot be interpreted, return NULL_TREE. */
7740 static tree
7742 {
7756 {
7759 {
7766 else
7768 }
7769 else
7775 else
7778 }
7781 }
7784 /* Subroutine of native_interpret_expr. Interpret the contents of
7785 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7786 If the buffer cannot be interpreted, return NULL_TREE. */
7788 static tree
7790 {
7795 /* There are always 32 bits in each long, no matter the size of
7796 the hosts long. We handle floating point representations with
7797 up to 192 bits. */
7798 REAL_VALUE_TYPE r;
7809 {
7812 {
7819 else
7821 }
7822 else
7827 }
7831 }
7834 /* Subroutine of native_interpret_expr. Interpret the contents of
7835 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7836 If the buffer cannot be interpreted, return NULL_TREE. */
7838 static tree
7840 {
7855 }
7858 /* Subroutine of native_interpret_expr. Interpret the contents of
7859 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7860 If the buffer cannot be interpreted, return NULL_TREE. */
7862 static tree
7864 {
7876 {
7881 }
7883 }
7886 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7887 the buffer PTR of length LEN as a constant of type TYPE. For
7888 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7889 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7890 return NULL_TREE. */
7892 tree
7894 {
7896 {
7913 }
7914 }
7917 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7918 TYPE at compile-time. If we're unable to perform the conversion
7919 return NULL_TREE. */
7921 static tree
7923 {
7924 /* We support up to 512-bit values (for V8DFmode). */
7928 /* Check that the host and target are sane. */
7937 }
7939 /* Build an expression for the address of T. Folds away INDIRECT_REF
7940 to avoid confusing the gimplify process. When IN_FOLD is true
7941 avoid modifications of T. */
7943 static tree
7945 {
7946 /* The size of the object is not relevant when talking about its address. */
7950 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7953 {
7958 }
7960 {
7970 }
7971 else
7975 }
7977 /* Build an expression for the address of T with type PTRTYPE. This
7978 function modifies the input parameter 'T' by sometimes setting the
7979 TREE_ADDRESSABLE flag. */
7981 tree
7983 {
7985 }
7987 /* Build an expression for the address of T. This function modifies
7988 the input parameter 'T' by sometimes setting the TREE_ADDRESSABLE
7989 flag. When called from fold functions, use fold_addr_expr instead. */
7991 tree
7993 {
7997 }
7999 /* Same as build_fold_addr_expr, builds an expression for the address
8000 of T, but avoids touching the input node 't'. Fold functions
8001 should use this version. */
8003 static tree
8005 {
8009 }
8011 /* Fold a unary expression of code CODE and type TYPE with operand
8012 OP0. Return the folded expression if folding is successful.
8013 Otherwise, return NULL_TREE. */
8015 tree
8017 {
8018 tree tem;
8019 tree arg0;
8027 {
8030 {
8031 /* Don't use STRIP_NOPS, because signedness of argument type
8032 matters. */
8034 }
8035 else
8036 {
8037 /* Strip any conversions that don't change the mode. This
8038 is safe for every expression, except for a comparison
8039 expression because its signedness is derived from its
8040 operands.
8042 Note that this is done as an internal manipulation within
8043 the constant folder, in order to find the simplest
8044 representation of the arguments so that their form can be
8045 studied. In any cases, the appropriate type conversions
8046 should be put back in the tree that will get out of the
8047 constant folder. */
8049 }
8050 }
8053 {
8060 {
8072 /* If this was a conversion, and all we did was to move into
8073 inside the COND_EXPR, bring it back out. But leave it if
8074 it is a conversion from integer to integer and the
8075 result precision is no wider than a word since such a
8076 conversion is cheap and may be optimized away by combine,
8077 while it couldn't if it were outside the COND_EXPR. Then return
8078 so we don't get into an infinite recursion loop taking the
8079 conversion out and then back in. */
8091 && (INTEGRAL_TYPE_P
8103 }
8105 {
8107 {
8111 }
8115 integer_one_node),
8117 integer_zero_node));
8118 }
8119 }
8122 {
8124 /* Re-association barriers around constants and other re-association
8125 barriers can be removed. */
8131 CASE_CONVERT:
8137 /* If we have (type) (a CMP b) and type is an integral type, return
8138 new expression involving the new type. */
8143 /* Handle cases of two conversions in a row. */
8145 {
8167 /* In addition to the cases of two conversions in a row
8168 handled below, if we are converting something to its own
8169 type via an object of identical or wider precision, neither
8170 conversion is needed. */
8177 /* Likewise, if the intermediate and final types are either both
8178 float or both integer, we don't need the middle conversion if
8179 it is wider than the final type and doesn't change the signedness
8180 (for integers). Avoid this if the final type is a pointer
8181 since then we sometimes need the inner conversion. Likewise if
8182 the outer has a precision not equal to the size of its mode. */
8191 && ! final_ptr
8195 /* If we have a sign-extension of a zero-extended value, we can
8196 replace that by a single zero-extension. */
8202 /* Two conversions in a row are not needed unless:
8203 - some conversion is floating-point (overstrict for now), or
8204 - some conversion is a vector (overstrict for now), or
8205 - the intermediate type is narrower than both initial and
8206 final, or
8207 - the intermediate type and innermost type differ in signedness,
8208 and the outermost type is wider than the intermediate, or
8209 - the initial type is a pointer type and the precisions of the
8210 intermediate and final types differ, or
8211 - the final type is a pointer type and the precisions of the
8212 initial and intermediate types differ. */
8226 }
8228 /* Handle (T *)&A.B.C for A being of type T and B and C
8229 living at offset zero. This occurs frequently in
8230 C++ upcasting and then accessing the base. */
8234 {
8236 tree offset;
8242 /* If the reference was to a (constant) zero offset, we can use
8243 the address of the base if it has the same base type
8244 as the result type. */
8249 }
8253 /* Detect assigning a bitfield. */
8255 && DECL_BIT_FIELD
8257 {
8258 /* Don't leave an assignment inside a conversion
8259 unless assigning a bitfield. */
8261 /* First do the assignment, then return converted constant. */
8266 }
8268 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8269 constants (if x has signed type, the sign bit cannot be set
8270 in c). This folds extension into the BIT_AND_EXPR.
8271 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8272 very likely don't have maximal range for their precision and this
8273 transformation effectively doesn't preserve non-maximal ranges. */
8277 /* Not if the conversion is to the sub-type. */
8279 {
8289 <= HOST_BITS_PER_WIDE_INT
8291 {
8298 #ifdef LOAD_EXTEND_OP
8300 && !flag_syntax_only
8303 {
8307 }
8308 #endif
8309 }
8311 {
8317 }
8318 }
8320 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8321 when one of the new casts will fold away. Conservatively we assume
8322 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8328 {
8334 }
8336 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8337 of the same precision, and X is an integer type not narrower than
8338 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8344 {
8349 }
8351 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8352 type of X and Y (integer types only). */
8357 {
8358 /* Be careful not to introduce new overflows. */
8359 tree mult_type;
8362 else
8366 {
8373 }
8374 }
8389 /* For integral conversions with the same precision or pointer
8390 conversions use a NOP_EXPR instead. */
8396 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8397 a sub-type to its base type as generated by the Ada FE. */
8402 /* Strip inner integral conversions that do not change the precision. */
8425 /* Convert fabs((double)float) into (double)fabsf(float). */
8428 {
8433 targ0));
8434 }
8435 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8441 /* Strip sign ops from argument. */
8443 {
8447 }
8454 {
8459 }
8461 {
8466 }
8476 /* Convert ~ (-A) to A - 1. */
8481 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8489 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8502 /* Perform BIT_NOT_EXPR on each element individually. */
8504 {
8509 {
8511 {
8517 }
8518 else
8521 }
8524 }
8529 /* The argument to invert_truthvalue must have Boolean type. */
8533 /* Note that the operand of this must be an int
8534 and its values must be 0 or 1.
8535 ("true" is a fixed value perhaps depending on the language,
8536 but we don't handle values other than 1 correctly yet.) */
8551 {
8559 }
8561 {
8565 }
8567 {
8571 {
8580 }
8581 }
8593 {
8601 }
8603 {
8607 }
8609 {
8613 {
8622 }
8623 }
8629 }
8632 /* If the operation was a conversion do _not_ mark a resulting constant
8633 with TREE_OVERFLOW if the original constant was not. These conversions
8634 have implementation defined behavior and retaining the TREE_OVERFLOW
8635 flag here would confuse later passes such as VRP. */
8636 tree
8638 {
8647 }
8649 /* Fold a binary expression of code CODE and type TYPE with operands
8650 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8651 Return the folded expression if folding is successful. Otherwise,
8652 return NULL_TREE. */
8654 static tree
8656 {
8663 else
8666 /* MIN (MAX (a, b), b) == b. */
8671 /* MIN (MAX (b, a), b) == b. */
8677 /* MIN (a, MAX (a, b)) == a. */
8683 /* MIN (a, MAX (b, a)) == a. */
8690 }
8692 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8693 by changing CODE to reduce the magnitude of constants involved in
8694 ARG0 of the comparison.
8695 Returns a canonicalized comparison tree if a simplification was
8696 possible, otherwise returns NULL_TREE.
8697 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8698 valid if signed overflow is undefined. */
8700 static tree
8704 {
8710 /* Match A +- CST code arg1 and CST code arg1. We can change the
8711 first form only if overflow is undefined. */
8713 /* In principle pointers also have undefined overflow behavior,
8714 but that causes problems elsewhere. */
8722 /* Identify the constant in arg0 and its sign. */
8725 else
8729 /* Overflowed constants and zero will cause problems. */
8734 /* See if we can reduce the magnitude of the constant in
8735 arg0 by changing the comparison code. */
8737 {
8738 /* CST <= arg1 -> CST-1 < arg1. */
8741 /* -CST < arg1 -> -CST-1 <= arg1. */
8744 /* CST > arg1 -> CST-1 >= arg1. */
8747 /* -CST >= arg1 -> -CST-1 > arg1. */
8750 else
8752 /* arg1 code' CST' might be more canonical. */
8754 }
8755 else
8756 {
8757 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8761 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8765 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8769 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8773 else
8776 }
8778 /* Now build the constant reduced in magnitude. But not if that
8779 would produce one outside of its types range. */
8787 /* We cannot swap the comparison here as that would cause us to
8788 endlessly recurse. */
8796 /* If swapping might yield to a more canonical form, do so. */
8799 else
8801 }
8803 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8804 overflow further. Try to decrease the magnitude of constants involved
8805 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8806 and put sole constants at the second argument position.
8807 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8809 static tree
8812 {
8813 tree t;
8818 /* Try canonicalization by simplifying arg0. */
8823 {
8827 }
8829 /* Try canonicalization by simplifying arg1 using the swapped
8830 comparison. */
8838 }
8840 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8841 space. This is used to avoid issuing overflow warnings for
8842 expressions like &p->x which can not wrap. */
8844 static bool
8846 {
8857 {
8860 }
8863 else
8864 {
8867 }
8882 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8883 array. */
8885 {
8886 HOST_WIDE_INT base_size;
8891 }
8894 }
8896 /* Subroutine of fold_binary. This routine performs all of the
8897 transformations that are common to the equality/inequality
8898 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8899 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8900 fold_binary should call fold_binary. Fold a comparison with
8901 tree code CODE and type TYPE with operands OP0 and OP1. Return
8902 the folded comparison or NULL_TREE. */
8904 static tree
8906 {
8919 /* If one arg is a real or integer constant, put it last. */
8923 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8930 {
8934 tree lhs;
8941 /* If the constant operation overflowed this can be
8942 simplified as a comparison against INT_MAX/INT_MIN. */
8945 {
8949 /* Get the sign of the constant on the lhs if the
8950 operation were VARIABLE + CONST1. */
8954 /* The sign of the constant determines if we overflowed
8955 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8956 Canonicalize to the INT_MIN overflow by swapping the comparison
8957 if necessary. */
8961 /* We now can look at the canonicalized case
8962 VARIABLE + 1 CODE2 INT_MIN
8963 and decide on the result. */
8972 }
8977 {
8979 "when changing X +- C1 cmp C2 to "
8981 WARN_STRICT_OVERFLOW_COMPARISON);
8983 }
8984 }
8986 /* For comparisons of pointers we can decompose it to a compile time
8987 comparison of the base objects and the offsets into the object.
8988 This requires at least one operand being an ADDR_EXPR or a
8989 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8995 {
9002 /* Get base and offset for the access. Strip ADDR_EXPR for
9003 get_inner_reference, but put it back by stripping INDIRECT_REF
9004 off the base object if possible. indirect_baseN will be true
9005 if baseN is not an address but refers to the object itself. */
9008 {
9014 else
9016 }
9018 {
9021 }
9025 {
9031 else
9033 }
9035 {
9038 }
9040 /* If we have equivalent bases we might be able to simplify. */
9043 {
9044 /* We can fold this expression to a constant if the non-constant
9045 offset parts are equal. */
9053 {
9060 "occur when comparing P +- C1 with "
9062 WARN_STRICT_OVERFLOW_CONDITIONAL);
9065 {
9079 }
9080 }
9081 /* We can simplify the comparison to a comparison of the variable
9082 offset parts if the constant offset parts are equal.
9083 Be careful to use signed size type here because otherwise we
9084 mess with array offsets in the wrong way. This is possible
9085 because pointer arithmetic is restricted to retain within an
9086 object and overflow on pointer differences is undefined as of
9087 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9091 {
9092 tree signed_size_type_node;
9095 /* By converting to signed size type we cover middle-end pointer
9096 arithmetic which operates on unsigned pointer types of size
9097 type size and ARRAY_REF offsets which are properly sign or
9098 zero extended from their type in case it is narrower than
9099 size type. */
9102 else
9106 else
9114 "occur when comparing P +- C1 with "
9116 WARN_STRICT_OVERFLOW_COMPARISON);
9119 }
9120 }
9121 /* For non-equal bases we can simplify if they are addresses
9122 of local binding decls or constants. */
9124 /* We know that !operand_equal_p (base0, base1, 0)
9125 because the if condition was false. But make
9126 sure two decls are not the same. */
9140 {
9145 }
9146 /* For equal offsets we can simplify to a comparison of the
9147 base addresses. */
9149 && (indirect_base0
9151 && (indirect_base1
9156 {
9162 }
9163 }
9165 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9166 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9167 the resulting offset is smaller in absolute value than the
9168 original one. */
9176 {
9181 tree cst;
9183 "occur when combining constants around "
9186 /* Put the constant on the side where it doesn't overflow and is
9187 of lower absolute value than before. */
9193 {
9196 variable1,
9199 }
9206 {
9211 variable2);
9212 }
9213 }
9215 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9216 signed arithmetic case. That form is created by the compiler
9217 often enough for folding it to be of value. One example is in
9218 computing loop trip counts after Operator Strength Reduction. */
9224 {
9233 "eliminating multiplication in comparison "
9235 WARN_STRICT_OVERFLOW_COMPARISON);
9237 /* If const1 is negative we swap the sense of the comparison. */
9242 }
9249 {
9257 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9262 /* (-a) CMP (-b) -> b CMP a */
9269 {
9270 REAL_VALUE_TYPE cst;
9273 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9280 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9281 /* a CMP (-0) -> a CMP 0 */
9286 /* x != NaN is always true, other ops are always false. */
9289 {
9292 }
9294 /* Fold comparisons against infinity. */
9296 {
9300 }
9301 }
9303 /* If this is a comparison of a real constant with a PLUS_EXPR
9304 or a MINUS_EXPR of a real constant, we can convert it into a
9305 comparison with a revised real constant as long as no overflow
9306 occurs when unsafe_math_optimizations are enabled. */
9318 /* Likewise, we can simplify a comparison of a real constant with
9319 a MINUS_EXPR whose first operand is also a real constant, i.e.
9320 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9321 floating-point types only if -fassociative-math is set. */
9332 /* Fold comparisons against built-in math functions. */
9334 && flag_unsafe_math_optimizations
9336 {
9340 {
9344 }
9345 }
9346 }
9350 {
9351 /* If we are widening one operand of an integer comparison,
9352 see if the other operand is similarly being widened. Perhaps we
9353 can do the comparison in the narrower type. */
9358 /* Or if we are changing signedness. */
9362 }
9364 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9365 constant, we can simplify it. */
9370 {
9374 }
9376 /* Simplify comparison of something with itself. (For IEEE
9377 floating-point, we can only do some of these simplifications.) */
9379 {
9381 {
9396 /* For NE, we can only do this simplification if integer
9397 or we don't honor IEEE floating point NaNs. */
9401 /* ... fall through ... */
9407 }
9408 }
9410 /* If we are comparing an expression that just has comparisons
9411 of two integer values, arithmetic expressions of those comparisons,
9412 and constants, we can simplify it. There are only three cases
9413 to check: the two values can either be equal, the first can be
9414 greater, or the second can be greater. Fold the expression for
9415 those three values. Since each value must be 0 or 1, we have
9416 eight possibilities, each of which corresponds to the constant 0
9417 or 1 or one of the six possible comparisons.
9419 This handles common cases like (a > b) == 0 but also handles
9420 expressions like ((x > y) - (y > x)) > 0, which supposedly
9421 occur in macroized code. */
9424 {
9429 /* Don't handle degenerate cases here; they should already
9430 have been handled anyway. */
9439 {
9443 /* We can't just pass T to eval_subst in case cval1 or cval2
9444 was the same as ARG1. */
9446 tree high_result
9450 arg1);
9451 tree equal_result
9455 arg1);
9456 tree low_result
9460 arg1);
9462 /* All three of these results should be 0 or 1. Confirm they are.
9463 Then use those values to select the proper code to use. */
9468 {
9469 /* Make a 3-bit mask with the high-order bit being the
9470 value for `>', the next for '=', and the low for '<'. */
9474 {
9476 /* Always false. */
9497 /* Always true. */
9499 }
9504 }
9505 }
9506 }
9508 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9509 into a single range test. */
9517 {
9521 }
9523 /* Fold ~X op ~Y as Y op X. */
9526 {
9531 }
9533 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9536 {
9542 }
9545 }
9548 /* Subroutine of fold_binary. Optimize complex multiplications of the
9549 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9550 argument EXPR represents the expression "z" of type TYPE. */
9552 static tree
9554 {
9559 {
9562 }
9564 {
9567 }
9568 else
9569 {
9573 }
9582 }
9585 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9586 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9587 guarantees that P and N have the same least significant log2(M) bits.
9588 N is not otherwise constrained. In particular, N is not normalized to
9589 0 <= N < M as is common. In general, the precise value of P is unknown.
9590 M is chosen as large as possible such that constant N can be determined.
9592 Returns M and sets *RESIDUE to N. */
9594 static unsigned HOST_WIDE_INT
9596 {
9603 {
9606 {
9608 tree offset;
9616 {
9619 else
9620 /* We don't handle more complicated offset expressions. */
9622 }
9623 }
9627 }
9629 {
9642 {
9645 }
9647 {
9650 {
9653 /* Compute the greatest power-of-2 divisor of op1. */
9657 /* If align is non-zero and less than *modulus, replace
9658 *modulus with align., If align is 0, then either op1 is 0
9659 or the greatest power-of-2 divisor of op1 doesn't fit in an
9660 unsigned HOST_WIDE_INT. In either case, no additional
9661 constraint is imposed. */
9666 }
9667 }
9668 }
9670 /* If we get here, we were unable to determine anything useful about the
9671 expression. */
9673 }
9676 /* Fold a binary expression of code CODE and type TYPE with operands
9677 OP0 and OP1. Return the folded expression if folding is
9678 successful. Otherwise, return NULL_TREE. */
9680 tree
9682 {
9696 /* Strip any conversions that don't change the mode. This is
9697 safe for every expression, except for a comparison expression
9698 because its signedness is derived from its operands. So, in
9699 the latter case, only strip conversions that don't change the
9700 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9701 preserved.
9703 Note that this is done as an internal manipulation within the
9704 constant folder, in order to find the simplest representation
9705 of the arguments so that their form can be studied. In any
9706 cases, the appropriate type conversions should be put back in
9707 the tree that will get out of the constant folder. */
9710 {
9713 }
9714 else
9715 {
9718 }
9720 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9721 constant but we can't do arithmetic on them. */
9728 {
9730 {
9731 /* Make sure type and arg0 have the same saturating flag. */
9735 }
9738 else
9742 {
9746 }
9747 }
9749 /* If this is a commutative operation, and ARG0 is a constant, move it
9750 to ARG1 to reduce the number of tests below. */
9755 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9757 First check for cases where an arithmetic operation is applied to a
9758 compound, conditional, or comparison operation. Push the arithmetic
9759 operation inside the compound or conditional to see if any folding
9760 can then be done. Convert comparison to conditional for this purpose.
9761 The also optimizes non-constant cases that used to be done in
9762 expand_expr.
9764 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9765 one of the operands is a comparison and the other is a comparison, a
9766 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9767 code below would make the expression more complex. Change it to a
9768 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9769 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9781 {
9785 boolean_type_node,
9793 }
9797 {
9803 op1));
9812 {
9818 }
9821 {
9827 }
9828 }
9831 {
9833 /* 0 +p index -> (type)index */
9837 /* PTR +p 0 -> PTR */
9841 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9848 /* index +p PTR -> PTR +p index */
9855 /* (PTR +p B) +p A -> PTR +p (B + A) */
9857 {
9858 tree inner;
9866 }
9868 /* PTR_CST +p CST -> CST1 */
9872 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9873 of the array. Loop optimizer sometimes produce this type of
9874 expressions. */
9876 {
9880 }
9885 /* A + (-B) -> A - B */
9890 /* (-A) + B -> B - A */
9898 {
9899 /* Convert ~A + 1 to -A. */
9905 /* ~X + X is -1. */
9908 {
9913 {
9916 }
9917 }
9919 /* X + ~X is -1. */
9922 {
9927 {
9930 }
9931 }
9933 /* X + (X / CST) * -CST is X % CST. */
9938 {
9946 }
9947 }
9949 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9950 same or one. Make sure type is not saturating.
9951 fold_plusminus_mult_expr will re-associate. */
9956 {
9960 }
9963 {
9967 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9968 with a constant, and the two constants have no bits in common,
9969 we should treat this as a BIT_IOR_EXPR since this may produce more
9970 simplifications. */
9978 {
9981 }
9983 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9984 (plus (plus (mult) (mult)) (foo)) so that we can
9985 take advantage of the factoring cases below. */
9992 {
9998 else
10020 parg1)));
10021 }
10022 }
10023 else
10024 {
10025 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10029 /* Likewise if the operands are reversed. */
10033 /* Convert X + -C into X - C. */
10036 {
10042 }
10044 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10045 to __complex__ ( x, y ). This is not the same for SNaNs or
10046 if signed zeros are involved. */
10050 {
10057 {
10061 {
10067 }
10069 {
10075 }
10076 }
10077 }
10085 /* Convert x+x into x*2.0. */
10091 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10092 We associate floats only if the user has specified
10093 -fassociative-math. */
10097 {
10102 {
10103 tree tree0;
10106 }
10107 }
10108 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10109 We associate floats only if the user has specified
10110 -fassociative-math. */
10114 {
10119 {
10120 tree tree0;
10123 }
10124 }
10125 }
10127 bit_rotate:
10128 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10129 is a rotate of A by C1 bits. */
10130 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10131 is a rotate of A by B bits. */
10132 {
10134 tree rtype;
10143 /* Only create rotates in complete modes. Other cases are not
10144 expanded properly. */
10146 {
10165 {
10173 TYPE_PRECISION
10178 ? LROTATE_EXPR
10181 }
10183 {
10191 TYPE_PRECISION
10196 ? LROTATE_EXPR
10199 }
10200 }
10201 }
10203 associate:
10204 /* In most languages, can't associate operations on floats through
10205 parentheses. Rather than remember where the parentheses were, we
10206 don't associate floats at all, unless the user has specified
10207 -fassociative-math.
10208 And, we need to make sure type is not saturating. */
10212 {
10217 /* Split both trees into variables, constants, and literals. Then
10218 associate each group together, the constants with literals,
10219 then the result with variables. This increases the chances of
10220 literals being recombined later and of generating relocatable
10221 expressions for the sum of a constant and literal. */
10226 /* With undefined overflow we can only associate constants
10227 with one variable. */
10231 {
10239 /* The only case we can still associate with two variables
10240 is if they are the same, modulo negation. */
10243 }
10245 /* Only do something if we found more than two objects. Otherwise,
10246 nothing has changed and we risk infinite recursion. */
10252 {
10253 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10262 /* Preserve the MINUS_EXPR if the negative part of the literal is
10263 greater than the positive part. Otherwise, the multiplicative
10264 folding code (i.e extract_muldiv) may be fooled in case
10265 unsigned constants are subtracted, like in the following
10266 example: ((X*2 + 4) - 8U)/2. */
10268 {
10272 {
10276 }
10277 else
10278 {
10282 }
10283 }
10285 {
10290 else
10291 {
10297 }
10298 }
10303 }
10304 }
10309 /* Pointer simplifications for subtraction, simple reassociations. */
10311 {
10312 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10315 {
10323 }
10324 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10326 {
10332 }
10333 }
10334 /* A - (-B) -> A + B */
10338 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10347 /* Convert -A - 1 to ~A. */
10355 /* Convert -1 - A to ~A. */
10361 /* X - (X / CST) * CST is X % CST. */
10374 {
10380 /* Fold A - (A & B) into ~B & A. */
10383 {
10385 {
10390 }
10392 {
10397 }
10398 }
10400 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10401 any power of 2 minus 1. */
10406 {
10412 {
10416 }
10417 }
10418 }
10420 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10424 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10425 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10426 (-ARG1 + ARG0) reduces to -ARG1. */
10430 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10431 __complex__ ( x, -y ). This is not the same for SNaNs or if
10432 signed zeros are involved. */
10436 {
10443 {
10447 {
10449 arg1r ? arg1r
10454 }
10456 {
10460 arg1i ? arg1i
10463 }
10464 }
10465 }
10467 /* Fold &x - &x. This can happen from &x.foo - &x.
10468 This is unsafe for certain floats even in non-IEEE formats.
10469 In IEEE, it is unsafe because it does wrong for NaNs.
10470 Also note that operand_equal_p is always false if an operand
10471 is volatile. */
10477 /* A - B -> A + (-B) if B is easily negatable. */
10480 /* Avoid this transformation if B is a positive REAL_CST. */
10488 /* Try folding difference of addresses. */
10489 {
10490 HOST_WIDE_INT diff;
10496 }
10498 /* Fold &a[i] - &a[j] to i-j. */
10503 {
10508 {
10516 }
10517 }
10525 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10526 same or one. Make sure type is not saturating.
10527 fold_plusminus_mult_expr will re-associate. */
10532 {
10536 }
10541 /* (-A) * (-B) -> A * B */
10552 {
10557 /* Transform x * -1 into -x. Make sure to do the negation
10558 on the original operand with conversions not stripped
10559 because we can only strip non-sign-changing conversions. */
10562 /* Transform x * -C into -x * C if x is easily negatable. */
10571 /* (a * (1 << b)) is (a << b) */
10581 /* (A + A) * C -> A * 2 * C */
10596 {
10599 "occur when simplifying "
10601 WARN_STRICT_OVERFLOW_MISC);
10603 }
10605 /* Optimize z * conj(z) for integer complex numbers. */
10612 }
10613 else
10614 {
10615 /* Maybe fold x * 0 to 0. The expressions aren't the same
10616 when x is NaN, since x * 0 is also NaN. Nor are they the
10617 same in modes with signed zeros, since multiplying a
10618 negative value by 0 gives -0, not +0. */
10623 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10628 /* Transform x * -1.0 into -x. */
10633 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10634 the result for floating point types due to rounding so it is applied
10635 only if -fassociative-math was specify. */
10640 {
10646 }
10648 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10650 {
10653 {
10656 }
10657 }
10659 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10660 This is not the same for NaNs or if signed zeros are
10661 involved. */
10667 {
10679 }
10681 /* Optimize z * conj(z) for floating point complex numbers.
10682 Guarded by flag_unsafe_math_optimizations as non-finite
10683 imaginary components don't produce scalar results. */
10694 {
10698 /* Optimizations of root(...)*root(...). */
10700 {
10705 /* Optimize sqrt(x)*sqrt(x) as x. */
10711 /* Optimize root(x)*root(y) as root(x*y). */
10715 }
10717 /* Optimize expN(x)*expN(y) as expN(x+y). */
10719 {
10725 }
10727 /* Optimizations of pow(...)*pow(...). */
10731 {
10737 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10739 {
10743 }
10745 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10747 {
10751 }
10752 }
10754 /* Optimize tan(x)*cos(x) as sin(x). */
10763 {
10768 }
10770 /* Optimize x*pow(x,c) as pow(x,c+1). */
10774 {
10780 {
10782 REAL_VALUE_TYPE c;
10783 tree arg;
10789 }
10790 }
10792 /* Optimize pow(x,c)*x as pow(x,c+1). */
10796 {
10802 {
10804 REAL_VALUE_TYPE c;
10805 tree arg;
10811 }
10812 }
10814 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10817 {
10821 {
10824 }
10825 }
10826 }
10827 }
10831 bit_ior:
10839 /* ~X | X is -1. */
10842 {
10846 }
10848 /* X | ~X is -1. */
10851 {
10855 }
10857 /* Canonicalize (X & C1) | C2. */
10861 {
10869 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10874 {
10878 }
10879 else
10880 {
10884 }
10886 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10891 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10892 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10893 mode which allows further optimizations. */
10903 {
10904 unsigned HOST_WIDE_INT mask
10908 {
10912 }
10913 }
10920 arg1);
10921 }
10923 /* (X & Y) | Y is (X, Y). */
10927 /* (X & Y) | X is (Y, X). */
10932 /* X | (X & Y) is (Y, X). */
10937 /* X | (Y & X) is (Y, X). */
10947 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10949 This results in more efficient code for machines without a NAND
10950 instruction. Combine will canonicalize to the first form
10951 which will allow use of NAND instructions provided by the
10952 backend if they exist. */
10955 {
10962 }
10964 /* See if this can be simplified into a rotate first. If that
10965 is unsuccessful continue in the association code. */
10976 /* ~X ^ X is -1. */
10979 {
10983 }
10985 /* X ^ ~X is -1. */
10988 {
10992 }
10994 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10995 with a constant, and the two constants have no bits in common,
10996 we should treat this as a BIT_IOR_EXPR since this may produce more
10997 simplifications. */
11005 {
11008 }
11010 /* (X | Y) ^ X -> Y & ~ X*/
11013 {
11016 arg1);
11020 }
11022 /* (Y | X) ^ X -> Y & ~ X*/
11025 {
11028 arg1);
11032 }
11034 /* X ^ (X | Y) -> Y & ~ X*/
11037 {
11040 arg0);
11044 }
11046 /* X ^ (Y | X) -> Y & ~ X*/
11049 {
11052 arg0);
11056 }
11058 /* Convert ~X ^ ~Y to X ^ Y. */
11065 /* Convert ~X ^ C to X ^ ~C. */
11072 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11079 /* Fold (X & Y) ^ Y as ~X & Y. */
11082 {
11087 }
11088 /* Fold (X & Y) ^ X as ~Y & X. */
11092 {
11097 }
11098 /* Fold X ^ (X & Y) as X & ~Y. */
11101 {
11106 }
11107 /* Fold X ^ (Y & X) as ~Y & X. */
11111 {
11116 }
11118 /* See if this can be simplified into a rotate first. If that
11119 is unsuccessful continue in the association code. */
11130 /* ~X & X is always zero. */
11135 /* X & ~X is always zero. */
11140 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11144 {
11152 }
11154 /* (X | Y) & Y is (X, Y). */
11158 /* (X | Y) & X is (Y, X). */
11163 /* X & (X | Y) is (Y, X). */
11168 /* X & (Y | X) is (Y, X). */
11174 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11178 {
11184 }
11185 /* Fold ~X & 1 as (X & 1) == 0. */
11188 {
11194 }
11196 /* Fold (X ^ Y) & Y as ~X & Y. */
11199 {
11204 }
11205 /* Fold (X ^ Y) & X as ~Y & X. */
11209 {
11214 }
11215 /* Fold X & (X ^ Y) as X & ~Y. */
11218 {
11223 }
11224 /* Fold X & (Y ^ X) as ~Y & X. */
11228 {
11233 }
11238 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11241 {
11242 unsigned int prec
11249 }
11251 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11253 This results in more efficient code for machines without a NOR
11254 instruction. Combine will canonicalize to the first form
11255 which will allow use of NOR instructions provided by the
11256 backend if they exist. */
11259 {
11266 }
11268 /* If arg0 is derived from the address of an object or function, we may
11269 be able to fold this expression using the object or function's
11270 alignment. */
11272 {
11278 /* This works because modulus is a power of 2. If this weren't the
11279 case, we'd have to replace it by its greatest power-of-2
11280 divisor: modulus & -modulus. */
11283 }
11285 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11286 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11287 if the new mask might be further optimized. */
11296 {
11298 unsigned HOST_WIDE_INT mask
11308 {
11311 /* See if more bits can be proven as zero because of
11312 zero extension. */
11315 {
11320 {
11322 /* See if we can shorten the right shift. */
11325 }
11326 }
11330 /* For arithmetic shift if sign bit could be set, zerobits
11331 can contain actually sign bits, so no transformation is
11332 possible, unless MASK masks them all away. In that
11333 case the shift needs to be converted into logical shift. */
11336 {
11339 else
11341 }
11342 }
11344 /* ((X << 16) & 0xff00) is (X, 0). */
11350 {
11353 /* Only do the transformation if NEWMASK is some integer
11354 mode's mask. */
11361 {
11363 {
11369 }
11370 else
11374 newmask));
11375 }
11376 }
11377 }
11382 /* Don't touch a floating-point divide by zero unless the mode
11383 of the constant can represent infinity. */
11389 /* Optimize A / A to 1.0 if we don't care about
11390 NaNs or Infinities. Skip the transformation
11391 for non-real operands. */
11396 {
11400 }
11402 /* The complex version of the above A / A optimization. */
11405 {
11409 {
11411 /* omit_two_operands will call fold_convert for us. */
11413 }
11414 }
11416 /* (-A) / (-B) -> A / B */
11426 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11431 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11436 /* If ARG1 is a constant, we can convert this to a multiply by the
11437 reciprocal. This does not have the same rounding properties,
11438 so only do this if -freciprocal-math. We can actually
11439 always safely do it if ARG1 is a power of two, but it's hard to
11440 tell if it is or not in a portable manner. */
11442 {
11447 /* Find the reciprocal if optimizing and the result is exact. */
11449 {
11450 REAL_VALUE_TYPE r;
11453 {
11457 }
11458 }
11459 }
11460 /* Convert A/B/C to A/(B*C). */
11467 /* Convert A/(B/C) to (A/B)*C. */
11475 /* Convert C1/(X*C2) into (C1/C2)/X. */
11480 {
11486 }
11489 {
11493 /* Optimize sin(x)/cos(x) as tan(x). */
11499 {
11504 }
11506 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11512 {
11516 {
11520 }
11521 }
11523 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11524 NaNs or Infinities. */
11528 {
11535 {
11540 }
11541 }
11543 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11544 NaNs or Infinities. */
11548 {
11555 {
11559 {
11563 tmp);
11564 }
11565 }
11566 }
11568 /* Optimize pow(x,c)/x as pow(x,c-1). */
11572 {
11578 {
11580 REAL_VALUE_TYPE c;
11581 tree arg;
11587 }
11588 }
11590 /* Optimize a/root(b/c) into a*root(c/b). */
11592 {
11596 {
11605 }
11606 }
11608 /* Optimize x/expN(y) into x*expN(-y). */
11610 {
11615 }
11617 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11621 {
11628 }
11629 }
11634 /* Simplify A / (B << N) where A and B are positive and B is
11635 a power of 2, to A >> (N + log2(B)). */
11640 {
11643 {
11650 WARN_STRICT_OVERFLOW_MISC);
11656 }
11657 }
11659 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11660 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11666 /* Fall thru */
11675 /* X / -1 is -X. */
11682 /* Convert -A / -B to A / B when the type is signed and overflow is
11683 undefined. */
11687 {
11690 "when distributing negation across "
11692 WARN_STRICT_OVERFLOW_MISC);
11696 }
11700 {
11703 "when distributing negation across "
11705 WARN_STRICT_OVERFLOW_MISC);
11709 }
11711 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11712 operation, EXACT_DIV_EXPR.
11714 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11715 At one time others generated faster code, it's not clear if they do
11716 after the last round to changes to the DIV code in expmed.c. */
11725 {
11729 WARN_STRICT_OVERFLOW_MISC);
11731 }
11739 /* X % 1 is always zero, but be sure to preserve any side
11740 effects in X. */
11744 /* X % 0, return X % 0 unchanged so that we can get the
11745 proper warnings and errors. */
11749 /* 0 % X is always zero, but be sure to preserve any side
11750 effects in X. Place this after checking for X == 0. */
11754 /* X % -1 is zero. */
11761 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11762 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11767 {
11769 /* Also optimize A % (C << N) where C is a power of 2,
11770 to A & ((C << N) - 1). */
11775 {
11780 "occur when simplifying "
11782 WARN_STRICT_OVERFLOW_MISC);
11786 }
11787 }
11789 /* X % -C is the same as X % C. */
11796 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11801 /* X % -Y is the same as X % Y. */
11812 {
11816 WARN_STRICT_OVERFLOW_MISC);
11818 }
11829 /* Optimize -1 >> x for arithmetic right shifts. */
11833 /* ... fall through ... */
11836 shift:
11842 /* Since negative shift count is not well-defined,
11843 don't try to compute it in the compiler. */
11847 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11852 {
11856 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11857 being well defined. */
11859 {
11864 else
11866 }
11870 }
11872 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11873 into x & ((unsigned)-1 >> c) for unsigned types. */
11881 {
11884 tree lshift;
11885 tree arg00;
11888 {
11895 }
11896 }
11898 /* Rewrite an LROTATE_EXPR by a constant into an
11899 RROTATE_EXPR by a new constant. */
11901 {
11906 }
11908 /* If we have a rotate of a bit operation with the rotate count and
11909 the second operand of the bit operation both constant,
11910 permute the two operations. */
11922 /* Two consecutive rotates adding up to the precision of the
11923 type can be ignored. */
11934 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11935 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11936 if the latter can be further optimized. */
11941 {
11944 arg1);
11947 arg1);
11951 }
11979 /* Note that the operands of this must be ints
11980 and their values must be 0 or 1.
11981 ("true" is a fixed value perhaps depending on the language.) */
11982 /* If first arg is constant zero, return it. */
11986 /* If either arg is constant true, drop it. */
11990 /* Preserve sequence points. */
11993 /* If second arg is constant zero, result is zero, but first arg
11994 must be evaluated. */
11997 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11998 case will be handled here. */
12002 /* !X && X is always false. */
12006 /* X && !X is always false. */
12011 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12012 means A >= Y && A != MAX, but in this case we know that
12013 A < X <= MAX. */
12017 {
12025 }
12027 truth_andor:
12028 /* We only do these simplifications if we are optimizing. */
12032 /* Check for things like (A || B) && (A || C). We can convert this
12033 to A || (B && C). Note that either operator can be any of the four
12034 truth and/or operations and the transformation will still be
12035 valid. Also note that we only care about order for the
12036 ANDIF and ORIF operators. If B contains side effects, this
12037 might change the truth-value of A. */
12044 {
12064 /* This case if tricky because we must either have commutative
12065 operators or else A10 must not have side-effects. */
12071 a01);
12072 }
12074 /* See if we can build a range comparison. */
12078 /* Check for the possibility of merging component references. If our
12079 lhs is another similar operation, try to merge its rhs with our
12080 rhs. Then try to merge our lhs and rhs. */
12092 /* Note that the operands of this must be ints
12093 and their values must be 0 or true.
12094 ("true" is a fixed value perhaps depending on the language.) */
12095 /* If first arg is constant true, return it. */
12099 /* If either arg is constant zero, drop it. */
12103 /* Preserve sequence points. */
12106 /* If second arg is constant true, result is true, but we must
12107 evaluate first arg. */
12110 /* Likewise for first arg, but note this only occurs here for
12111 TRUTH_OR_EXPR. */
12115 /* !X || X is always true. */
12119 /* X || !X is always true. */
12127 /* If the second arg is constant zero, drop it. */
12130 /* If the second arg is constant true, this is a logical inversion. */
12132 {
12133 /* Only call invert_truthvalue if operand is a truth value. */
12136 else
12139 }
12140 /* Identical arguments cancel to zero. */
12144 /* !X ^ X is always true. */
12149 /* X ^ !X is always true. */
12162 /* bool_var != 0 becomes bool_var. */
12167 /* bool_var == 1 becomes bool_var. */
12172 /* bool_var != 1 becomes !bool_var. */
12177 /* bool_var == 0 becomes !bool_var. */
12182 /* If this is an equality comparison of the address of two non-weak,
12183 unaliased symbols neither of which are extern (since we do not
12184 have access to attributes for externs), then we know the result. */
12197 {
12198 /* We know that we're looking at the address of two
12199 non-weak, unaliased, static _DECL nodes.
12201 It is both wasteful and incorrect to call operand_equal_p
12202 to compare the two ADDR_EXPR nodes. It is wasteful in that
12203 all we need to do is test pointer equality for the arguments
12204 to the two ADDR_EXPR nodes. It is incorrect to use
12205 operand_equal_p as that function is NOT equivalent to a
12206 C equality test. It can in fact return false for two
12207 objects which would test as equal using the C equality
12208 operator. */
12212 type);
12213 }
12215 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12216 a MINUS_EXPR of a constant, we can convert it into a comparison with
12217 a revised constant as long as no overflow occurs. */
12229 /* Similarly for a NEGATE_EXPR. */
12237 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12246 /* Transform comparisons of the form X +- C CMP X. */
12252 {
12259 else
12262 }
12264 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12265 for !=. Don't do this for ordered comparisons due to overflow. */
12271 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12276 /* If this is an EQ or NE comparison with zero and ARG0 is
12277 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12278 two operations, but the latter can be done in one less insn
12279 on machines that have only two-operand insns or on which a
12280 constant cannot be the first operand. */
12283 {
12288 {
12295 }
12298 {
12305 }
12306 }
12308 /* If this is an NE or EQ comparison of zero against the result of a
12309 signed MOD operation whose second operand is a power of 2, make
12310 the MOD operation unsigned since it is simpler and equivalent. */
12318 {
12328 }
12330 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12331 C1 is a valid shift constant, and C2 is a power of two, i.e.
12332 a single bit. */
12336 == INTEGER_CST
12339 {
12344 /* Check for a valid shift count. */
12347 {
12351 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12352 can be rewritten as (X & (C2 << C1)) != 0. */
12354 {
12358 }
12359 /* Otherwise, for signed (arithmetic) shifts,
12360 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12361 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12365 /* Otherwise, of unsigned (logical) shifts,
12366 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12367 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12368 else
12372 arg000);
12373 }
12374 }
12376 /* If this is an NE comparison of zero with an AND of one, remove the
12377 comparison since the AND will give the correct value. */
12384 /* If we have (A & C) == C where C is a power of 2, convert this into
12385 (A & C) != 0. Similarly for NE_EXPR. */
12391 integer_zero_node));
12393 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12394 bit, then fold the expression into A < 0 or A >= 0. */
12399 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12400 Similarly for NE_EXPR. */
12404 {
12413 }
12415 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12416 Similarly for NE_EXPR. */
12420 {
12427 }
12429 /* If this is a comparison of a field, we may be able to simplify it. */
12432 /* Handle the constant case even without -O
12433 to make sure the warnings are given. */
12435 {
12439 }
12441 /* Optimize comparisons of strlen vs zero to a compare of the
12442 first character of the string vs zero. To wit,
12443 strlen(ptr) == 0 => *ptr == 0
12444 strlen(ptr) != 0 => *ptr != 0
12445 Other cases should reduce to one of these two (or a constant)
12446 due to the return value of strlen being unsigned. */
12449 {
12457 {
12461 }
12462 }
12464 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12465 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12469 {
12476 {
12478 {
12481 }
12484 }
12485 }
12487 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12493 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12498 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12505 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12513 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12514 (X & C) == 0 when C is a single bit. */
12519 {
12525 }
12527 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12528 constant C is a power of two, i.e. a single bit. */
12535 {
12539 }
12541 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12542 when is C is a power of two, i.e. a single bit. */
12549 {
12555 }
12559 {
12562 }
12564 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12571 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12574 {
12586 arg01),
12594 arg01),
12602 arg00),
12610 arg00),
12612 }
12616 {
12623 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12624 operand_equal_p guarantees no side-effects so we don't need
12625 to use omit_one_operand on Z. */
12635 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12642 arg10);
12643 }
12645 /* Attempt to simplify equality/inequality comparisons of complex
12646 values. Only lower the comparison if the result is known or
12647 can be simplified to a single scalar comparison. */
12652 {
12657 {
12660 }
12661 else
12662 {
12665 }
12668 {
12671 }
12672 else
12673 {
12676 }
12680 {
12682 {
12687 }
12688 else
12689 {
12694 }
12695 }
12699 {
12701 {
12706 }
12707 else
12708 {
12713 }
12714 }
12715 }
12727 /* Transform comparisons of the form X +- C CMP X. */
12734 {
12741 else
12744 /* (X - c) > X becomes false. */
12748 {
12752 "occur when assuming that (X - c) > X "
12754 WARN_STRICT_OVERFLOW_ALL);
12756 }
12758 /* Likewise (X + c) < X becomes false. */
12762 {
12766 "occur when assuming that "
12768 WARN_STRICT_OVERFLOW_ALL);
12770 }
12772 /* Convert (X - c) <= X to true. */
12777 {
12781 "occur when assuming that "
12783 WARN_STRICT_OVERFLOW_ALL);
12785 }
12787 /* Convert (X + c) >= X to true. */
12792 {
12796 "occur when assuming that "
12798 WARN_STRICT_OVERFLOW_ALL);
12800 }
12803 {
12804 /* Convert X + c > X and X - c < X to true for integers. */
12808 {
12811 "not occur when assuming that "
12813 WARN_STRICT_OVERFLOW_ALL);
12815 }
12820 {
12823 "not occur when assuming that "
12825 WARN_STRICT_OVERFLOW_ALL);
12827 }
12829 /* Convert X + c <= X and X - c >= X to false for integers. */
12833 {
12836 "not occur when assuming that "
12838 WARN_STRICT_OVERFLOW_ALL);
12840 }
12845 {
12848 "not occur when assuming that "
12850 WARN_STRICT_OVERFLOW_ALL);
12852 }
12853 }
12854 }
12856 /* Comparisons with the highest or lowest possible integer of
12857 the specified precision will have known values. */
12858 {
12865 {
12866 HOST_WIDE_INT signed_max_hi;
12871 {
12878 {
12882 }
12883 else
12884 {
12888 }
12889 }
12890 else
12891 {
12900 {
12903 }
12904 else
12905 {
12908 }
12909 }
12914 {
12927 /* The GE_EXPR and LT_EXPR cases above are not normally
12928 reached because of previous transformations. */
12932 }
12934 == max_hi
12937 {
12943 arg1);
12949 arg1);
12952 }
12954 == min_hi
12957 {
12972 }
12974 == min_hi
12977 {
12982 arg1);
12987 arg1);
12990 }
12995 /* We will flip the signedness of the comparison operator
12996 associated with the mode of arg1, so the sign bit is
12997 specified by this mode. Check that arg1 is the signed
12998 max associated with this sign bit. */
13000 /* signed_type does not work on pointer types. */
13002 {
13003 /* The following case also applies to X < signed_max+1
13004 and X >= signed_max+1 because previous transformations. */
13006 {
13007 tree st;
13012 }
13013 }
13014 }
13015 }
13017 /* If we are comparing an ABS_EXPR with a constant, we can
13018 convert all the cases into explicit comparisons, but they may
13019 well not be faster than doing the ABS and one comparison.
13020 But ABS (X) <= C is a range comparison, which becomes a subtraction
13021 and a comparison, and is probably faster. */
13035 /* Convert ABS_EXPR<x> >= 0 to true. */
13042 {
13045 "when simplifying comparison of "
13047 WARN_STRICT_OVERFLOW_CONDITIONAL);
13049 }
13051 /* Convert ABS_EXPR<x> < 0 to false. */
13056 {
13059 "when simplifying comparison of "
13061 WARN_STRICT_OVERFLOW_CONDITIONAL);
13063 }
13065 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13066 and similarly for >= into !=. */
13081 return
13100 {
13104 }
13106 /* If the first operand is NaN, the result is constant. */
13110 {
13112 ? integer_zero_node
13115 }
13117 /* If the second operand is NaN, the result is constant. */
13121 {
13123 ? integer_zero_node
13126 }
13128 /* Simplify unordered comparison of something with itself. */
13134 && !flag_trapping_math
13138 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13139 {
13150 }
13155 /* When pedantic, a compound expression can be neither an lvalue
13156 nor an integer constant expression. */
13159 /* Don't let (0, 0) be null pointer constant. */
13173 /* An ASSERT_EXPR should never be passed to fold_binary. */
13179 }
13181 /* Callback for walk_tree, looking for LABEL_EXPR.
13182 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13183 Do not check the sub-tree of GOTO_EXPR. */
13185 static tree
13189 {
13191 {
13196 /* no break */
13199 }
13200 }
13202 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13203 accessible from outside the sub-tree. Returns NULL_TREE if no
13204 addressable label is found. */
13206 static bool
13208 {
13210 }
13212 /* Fold a ternary expression of code CODE and type TYPE with operands
13213 OP0, OP1, and OP2. Return the folded expression if folding is
13214 successful. Otherwise, return NULL_TREE. */
13216 tree
13218 {
13219 tree tem;
13226 /* Strip any conversions that don't change the mode. This is safe
13227 for every expression, except for a comparison expression because
13228 its signedness is derived from its operands. So, in the latter
13229 case, only strip conversions that don't change the signedness.
13231 Note that this is done as an internal manipulation within the
13232 constant folder, in order to find the simplest representation of
13233 the arguments so that their form can be studied. In any cases,
13234 the appropriate type conversions should be put back in the tree
13235 that will get out of the constant folder. */
13237 {
13240 }
13243 {
13246 }
13249 {
13253 {
13259 }
13263 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13264 so all simple results must be passed through pedantic_non_lvalue. */
13266 {
13269 /* Only optimize constant conditions when the selected branch
13270 has the same type as the COND_EXPR. This avoids optimizing
13271 away "c ? x : throw", where the throw has a void type.
13272 Avoid throwing away that operand which contains label. */
13279 }
13283 /* If we have A op B ? A : C, we may be able to convert this to a
13284 simpler expression, depending on the operation and the values
13285 of B and C. Signed zeros prevent all of these transformations,
13286 for reasons given above each one.
13288 Also try swapping the arguments and inverting the conditional. */
13293 {
13297 }
13301 op2,
13304 {
13307 {
13311 }
13312 }
13314 /* If the second operand is simpler than the third, swap them
13315 since that produces better jump optimization results. */
13318 {
13319 /* See if this can be inverted. If it can't, possibly because
13320 it was a floating-point inequality comparison, don't do
13321 anything. */
13325 }
13327 /* Convert A ? 1 : 0 to simply A. */
13330 /* If we try to convert OP0 to our type, the
13331 call to fold will try to move the conversion inside
13332 a COND, which will recurse. In that case, the COND_EXPR
13333 is probably the best choice, so leave it alone. */
13337 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13338 over COND_EXPR in cases such as floating point comparisons. */
13345 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13350 {
13351 /* sign_bit_p only checks ARG1 bits within A's precision.
13352 If <sign bit of A> has wider type than A, bits outside
13353 of A's precision in <sign bit of A> need to be checked.
13354 If they are all 0, this optimization needs to be done
13355 in unsigned A's type, if they are all 1 in signed A's type,
13356 otherwise this can't be done. */
13361 {
13363 HOST_WIDE_INT mask_hi;
13365 tree tem_type;
13373 {
13377 }
13378 else
13379 {
13383 }
13385 {
13389 }
13390 else
13396 {
13399 }
13402 {
13405 }
13406 else
13408 }
13415 arg1)));
13416 }
13418 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13419 already handled above. */
13424 {
13433 }
13435 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13436 is probably obsolete because the first operand should be a
13437 truth value (that's why we have the two cases above), but let's
13438 leave it in until we can confirm this for all front-ends. */
13449 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13455 arg1);
13457 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13461 {
13462 /* Only perform transformation if ARG0 is easily inverted. */
13467 arg1);
13468 }
13470 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13474 {
13475 /* Only perform transformation if ARG0 is easily inverted. */
13480 op2);
13481 }
13483 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13489 op2);
13494 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13495 of fold_ternary on them. */
13502 {
13511 {
13516 else
13517 {
13519 tree value;
13523 }
13528 else
13530 }
13531 }
13533 /* A bit-field-ref that referenced the full argument can be stripped. */
13544 }
13546 /* Perform constant folding and related simplification of EXPR.
13547 The related simplifications include x*1 => x, x*0 => 0, etc.,
13548 and application of the associative law.
13549 NOP_EXPR conversions may be removed freely (as long as we
13550 are careful not to change the type of the overall expression).
13551 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13552 but we can constant-fold them if they have constant operands. */
13554 #ifdef ENABLE_FOLD_CHECKING
13555 # define fold(x) fold_1 (x)
13557 static
13558 #endif
13559 tree
13561 {
13565 tree tem;
13567 /* Return right away if a constant. */
13571 /* CALL_EXPR-like objects with variable numbers of operands are
13572 treated specially. */
13574 {
13576 {
13579 }
13581 }
13584 {
13589 {
13607 }
13608 }
13611 {
13613 {
13620 {
13625 /* Find a matching index by means of a binary search. */
13627 {
13643 else
13645 }
13646 }
13649 }
13657 }
13659 #ifdef ENABLE_FOLD_CHECKING
13660 #undef fold
13666 /* When --enable-checking=fold, compute a digest of expr before
13667 and after actual fold call to see if fold did not accidentally
13668 change original expr. */
13670 tree
13672 {
13673 tree ret;
13676 htab_t ht;
13695 }
13697 void
13699 {
13702 htab_t ht;
13712 }
13714 static void
13716 {
13718 }
13720 static void
13722 {
13728 recursive_label:
13742 {
13743 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13747 }
13754 {
13755 /* Allow these fields to be modified. */
13756 tree tmp;
13764 {
13767 }
13768 }
13777 {
13780 {
13794 }
13798 {
13811 }
13828 {
13834 }
13839 {
13843 }
13854 {
13857 }
13867 }
13868 }
13870 /* Helper function for outputting the checksum of a tree T. When
13871 debugging with gdb, you can "define mynext" to be "next" followed
13872 by "call debug_fold_checksum (op0)", then just trace down till the
13873 outputs differ. */
13875 void
13877 {
13892 }
13894 #endif
13896 /* Fold a unary tree expression with code CODE of type TYPE with an
13897 operand OP0. Return a folded expression if successful. Otherwise,
13898 return a tree expression with code CODE of type TYPE with an
13899 operand OP0. */
13901 tree
13903 {
13904 tree tem;
13905 #ifdef ENABLE_FOLD_CHECKING
13908 htab_t ht;
13915 #endif
13921 #ifdef ENABLE_FOLD_CHECKING
13929 #endif
13931 }
13933 /* Fold a binary tree expression with code CODE of type TYPE with
13934 operands OP0 and OP1. Return a folded expression if successful.
13935 Otherwise, return a tree expression with code CODE of type TYPE
13936 with operands OP0 and OP1. */
13938 tree
13940 MEM_STAT_DECL)
13941 {
13942 tree tem;
13943 #ifdef ENABLE_FOLD_CHECKING
13949 htab_t ht;
13961 #endif
13967 #ifdef ENABLE_FOLD_CHECKING
13983 #endif
13985 }
13987 /* Fold a ternary tree expression with code CODE of type TYPE with
13988 operands OP0, OP1, and OP2. Return a folded expression if
13989 successful. Otherwise, return a tree expression with code CODE of
13990 type TYPE with operands OP0, OP1, and OP2. */
13992 tree
13994 MEM_STAT_DECL)
13995 {
13996 tree tem;
13997 #ifdef ENABLE_FOLD_CHECKING
14005 htab_t ht;
14022 #endif
14029 #ifdef ENABLE_FOLD_CHECKING
14053 #endif
14055 }
14057 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14058 arguments in ARGARRAY, and a null static chain.
14059 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14060 of type TYPE from the given operands as constructed by build_call_array. */
14062 tree
14064 {
14065 tree tem;
14066 #ifdef ENABLE_FOLD_CHECKING
14072 htab_t ht;
14086 #endif
14090 #ifdef ENABLE_FOLD_CHECKING
14107 #endif
14109 }
14111 /* Perform constant folding and related simplification of initializer
14112 expression EXPR. These behave identically to "fold_buildN" but ignore
14113 potential run-time traps and exceptions that fold must preserve. */
14115 #define START_FOLD_INIT \
14116 int saved_signaling_nans = flag_signaling_nans;\
14117 int saved_trapping_math = flag_trapping_math;\
14118 int saved_rounding_math = flag_rounding_math;\
14119 int saved_trapv = flag_trapv;\
14120 int saved_folding_initializer = folding_initializer;\
14121 flag_signaling_nans = 0;\
14122 flag_trapping_math = 0;\
14123 flag_rounding_math = 0;\
14124 flag_trapv = 0;\
14125 folding_initializer = 1;
14127 #define END_FOLD_INIT \
14128 flag_signaling_nans = saved_signaling_nans;\
14129 flag_trapping_math = saved_trapping_math;\
14130 flag_rounding_math = saved_rounding_math;\
14131 flag_trapv = saved_trapv;\
14132 folding_initializer = saved_folding_initializer;
14134 tree
14136 {
14137 tree result;
14138 START_FOLD_INIT;
14142 END_FOLD_INIT;
14144 }
14146 tree
14148 {
14149 tree result;
14150 START_FOLD_INIT;
14154 END_FOLD_INIT;
14156 }
14158 tree
14160 tree op2)
14161 {
14162 tree result;
14163 START_FOLD_INIT;
14167 END_FOLD_INIT;
14169 }
14171 tree
14174 {
14175 tree result;
14176 START_FOLD_INIT;
14180 END_FOLD_INIT;
14182 }
14184 #undef START_FOLD_INIT
14185 #undef END_FOLD_INIT
14187 /* Determine if first argument is a multiple of second argument. Return 0 if
14188 it is not, or we cannot easily determined it to be.
14190 An example of the sort of thing we care about (at this point; this routine
14191 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14192 fold cases do now) is discovering that
14194 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14196 is a multiple of
14198 SAVE_EXPR (J * 8)
14200 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14202 This code also handles discovering that
14204 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14206 is a multiple of 8 so we don't have to worry about dealing with a
14207 possible remainder.
14209 Note that we *look* inside a SAVE_EXPR only to determine how it was
14210 calculated; it is not safe for fold to do much of anything else with the
14211 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14212 at run time. For example, the latter example above *cannot* be implemented
14213 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14214 evaluation time of the original SAVE_EXPR is not necessarily the same at
14215 the time the new expression is evaluated. The only optimization of this
14216 sort that would be valid is changing
14218 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14220 divided by 8 to
14222 SAVE_EXPR (I) * SAVE_EXPR (J)
14224 (where the same SAVE_EXPR (J) is used in the original and the
14225 transformed version). */
14227 int
14229 {
14237 {
14239 /* Bitwise and provides a power of two multiple. If the mask is
14240 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14243 /* FALLTHRU */
14256 {
14260 /* const_binop may not detect overflow correctly,
14261 so check for it explicitly here. */
14267 size_one_node,
14271 }
14275 /* Can't handle conversions from non-integral or wider integral type. */
14281 /* .. fall through ... */
14298 }
14299 }
14301 /* Return true if CODE or TYPE is known to be non-negative. */
14303 static bool
14305 {
14308 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14309 have a signed:1 type (where the value is -1 and 0). */
14312 }
14314 /* Return true if (CODE OP0) is known to be non-negative. If the return
14315 value is based on the assumption that signed overflow is undefined,
14316 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14317 *STRICT_OVERFLOW_P. */
14319 bool
14322 {
14327 {
14329 /* We can't return 1 if flag_wrapv is set because
14330 ABS_EXPR<INT_MIN> = INT_MIN. */
14334 {
14337 }
14344 strict_overflow_p);
14347 {
14352 {
14355 strict_overflow_p);
14357 {
14361 strict_overflow_p);
14362 }
14363 }
14365 {
14368 strict_overflow_p);
14372 }
14373 }
14378 }
14380 /* We don't know sign of `t', so be conservative and return false. */
14382 }
14384 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14385 value is based on the assumption that signed overflow is undefined,
14386 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14387 *STRICT_OVERFLOW_P. */
14389 bool
14392 {
14397 {
14402 strict_overflow_p)
14404 strict_overflow_p));
14406 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14407 both unsigned and at least 2 bits shorter than the result. */
14411 {
14416 {
14420 }
14421 }
14426 {
14427 /* x * x for floating point x is always non-negative. */
14431 strict_overflow_p)
14433 strict_overflow_p));
14434 }
14436 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14437 both unsigned and their total bits is shorter than the result. */
14441 {
14460 {
14470 }
14471 }
14477 strict_overflow_p)
14479 strict_overflow_p));
14490 strict_overflow_p)
14492 strict_overflow_p));
14499 strict_overflow_p);
14502 }
14504 /* We don't know sign of `t', so be conservative and return false. */
14506 }
14508 /* Return true if T is known to be non-negative. If the return
14509 value is based on the assumption that signed overflow is undefined,
14510 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14511 *STRICT_OVERFLOW_P. */
14513 bool
14515 {
14520 {
14532 strict_overflow_p)
14534 strict_overflow_p));
14538 }
14539 /* We don't know sign of `t', so be conservative and return false. */
14541 }
14543 /* Return true if T is known to be non-negative. If the return
14544 value is based on the assumption that signed overflow is undefined,
14545 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14546 *STRICT_OVERFLOW_P. */
14548 bool
14551 {
14554 {
14572 /* Always true. */
14576 /* sqrt(-0.0) is -0.0. */
14580 strict_overflow_p);
14613 /* True if the 1st argument is nonnegative. */
14615 strict_overflow_p);
14618 /* True if the 1st OR 2nd arguments are nonnegative. */
14620 strict_overflow_p)
14622 strict_overflow_p)));
14625 /* True if the 1st AND 2nd arguments are nonnegative. */
14627 strict_overflow_p)
14629 strict_overflow_p)));
14632 /* True if the 2nd argument is nonnegative. */
14634 strict_overflow_p);
14637 /* True if the 1st argument is nonnegative or the second
14638 argument is an even integer. */
14643 strict_overflow_p);
14646 /* True if the 1st argument is nonnegative or the second
14647 argument is an even integer valued real. */
14649 {
14650 REAL_VALUE_TYPE c;
14651 HOST_WIDE_INT n;
14656 {
14657 REAL_VALUE_TYPE cint;
14662 }
14663 }
14665 strict_overflow_p);
14669 }
14671 type);
14672 }
14674 /* Return true if T is known to be non-negative. If the return
14675 value is based on the assumption that signed overflow is undefined,
14676 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14677 *STRICT_OVERFLOW_P. */
14679 bool
14681 {
14687 {
14689 {
14693 /* If the initializer is non-void, then it's a normal expression
14694 that will be assigned to the slot. */
14698 /* Otherwise, the initializer sets the slot in some way. One common
14699 way is an assignment statement at the end of the initializer. */
14701 {
14709 else
14711 }
14715 strict_overflow_p);
14718 }
14721 {
14727 arg0,
14728 arg1,
14729 strict_overflow_p);
14730 }
14734 strict_overflow_p);
14737 strict_overflow_p);
14740 strict_overflow_p);
14745 }
14747 /* We don't know sign of `t', so be conservative and return false. */
14749 }
14751 /* Return true if T is known to be non-negative. If the return
14752 value is based on the assumption that signed overflow is undefined,
14753 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14754 *STRICT_OVERFLOW_P. */
14756 bool
14758 {
14765 {
14772 strict_overflow_p);
14778 strict_overflow_p);
14787 }
14790 {
14798 strict_overflow_p);
14803 strict_overflow_p);
14818 }
14819 }
14821 /* Return true if `t' is known to be non-negative. Handle warnings
14822 about undefined signed overflow. */
14824 bool
14826 {
14833 "determining that expression is always "
14835 WARN_STRICT_OVERFLOW_MISC);
14837 }
14840 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14841 For floating point we further ensure that T is not denormal.
14842 Similar logic is present in nonzero_address in rtlanal.h.
14844 If the return value is based on the assumption that signed overflow
14845 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14846 change *STRICT_OVERFLOW_P. */
14848 bool
14851 {
14853 {
14856 strict_overflow_p);
14859 {
14865 strict_overflow_p));
14866 }
14871 strict_overflow_p);
14875 }
14878 }
14880 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14881 For floating point we further ensure that T is not denormal.
14882 Similar logic is present in nonzero_address in rtlanal.h.
14884 If the return value is based on the assumption that signed overflow
14885 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14886 change *STRICT_OVERFLOW_P. */
14888 bool
14890 tree type,
14891 tree op0,
14893 {
14896 {
14900 {
14901 /* With the presence of negative values it is hard
14902 to say something. */
14909 /* One of operands must be positive and the other non-negative. */
14910 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14911 overflows, on a twos-complement machine the sum of two
14912 nonnegative numbers can never be zero. */
14914 strict_overflow_p)
14916 strict_overflow_p));
14917 }
14922 {
14924 strict_overflow_p)
14926 strict_overflow_p))
14927 {
14930 }
14931 }
14940 {
14943 }
14950 {
14954 /* When both operands are nonzero, then MAX must be too. */
14956 strict_overflow_p))
14959 /* MAX where operand 0 is positive is positive. */
14961 strict_overflow_p);
14962 }
14963 /* MAX where operand 1 is positive is positive. */
14968 {
14972 }
14977 strict_overflow_p)
14979 strict_overflow_p));
14983 }
14986 }
14988 /* Return true when T is an address and is known to be nonzero.
14989 For floating point we further ensure that T is not denormal.
14990 Similar logic is present in nonzero_address in rtlanal.h.
14992 If the return value is based on the assumption that signed overflow
14993 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14994 change *STRICT_OVERFLOW_P. */
14996 bool
14998 {
15001 {
15006 {
15012 /* Weak declarations may link to NULL. */
15016 /* Constants are never weak. */
15021 }
15029 {
15033 }
15038 }
15040 }
15042 /* Return true when T is an address and is known to be nonzero.
15043 For floating point we further ensure that T is not denormal.
15044 Similar logic is present in nonzero_address in rtlanal.h.
15046 If the return value is based on the assumption that signed overflow
15047 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15048 change *STRICT_OVERFLOW_P. */
15050 bool
15052 {
15056 /* Doing something useful for floating point would need more work. */
15062 {
15065 strict_overflow_p);
15071 strict_overflow_p);
15079 }
15082 {
15085 strict_overflow_p);
15093 strict_overflow_p);
15110 strict_overflow_p);
15114 strict_overflow_p);
15121 }
15123 }
15125 /* Return true when T is an address and is known to be nonzero.
15126 Handle warnings about undefined signed overflow. */
15128 bool
15130 {
15137 "determining that expression is always "
15139 WARN_STRICT_OVERFLOW_MISC);
15141 }
15143 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15144 attempt to fold the expression to a constant without modifying TYPE,
15145 OP0 or OP1.
15147 If the expression could be simplified to a constant, then return
15148 the constant. If the expression would not be simplified to a
15149 constant, then return NULL_TREE. */
15151 tree
15153 {
15156 }
15158 /* Given the components of a unary expression CODE, TYPE and OP0,
15159 attempt to fold the expression to a constant without modifying
15160 TYPE or OP0.
15162 If the expression could be simplified to a constant, then return
15163 the constant. If the expression would not be simplified to a
15164 constant, then return NULL_TREE. */
15166 tree
15168 {
15171 }
15173 /* If EXP represents referencing an element in a constant string
15174 (either via pointer arithmetic or array indexing), return the
15175 tree representing the value accessed, otherwise return NULL. */
15177 tree
15179 {
15183 {
15185 tree index;
15186 tree string;
15190 else
15191 {
15195 /* Optimize the special-case of a zero lower bound.
15197 We convert the low_bound to sizetype to avoid some problems
15198 with constant folding. (E.g. suppose the lower bound is 1,
15199 and its mode is QI. Without the conversion,l (ARRAY
15200 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15201 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15206 }
15219 }
15221 }
15223 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15224 an integer constant, real, or fixed-point constant.
15226 TYPE is the type of the result. */
15228 static tree
15230 {
15234 {
15236 {
15238 HOST_WIDE_INT high;
15246 }
15253 {
15254 FIXED_VALUE_TYPE f;
15259 /* Propagate overflow flags. */
15261 {
15264 }
15268 }
15272 }
15275 }
15277 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15278 an integer constant or real constant.
15280 TYPE is the type of the result. */
15282 tree
15284 {
15288 {
15290 /* If the value is unsigned, then the absolute value is
15291 the same as the ordinary value. */
15294 /* Similarly, if the value is non-negative. */
15297 /* If the value is negative, then the absolute value is
15298 its negation. */
15299 else
15300 {
15302 HOST_WIDE_INT high;
15308 }
15314 else
15320 }
15323 }
15325 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15326 constant. TYPE is the type of the result. */
15328 static tree
15330 {
15340 }
15342 /* Given CODE, a relational operator, the target type, TYPE and two
15343 constant operands OP0 and OP1, return the result of the
15344 relational operation. If the result is not a compile time
15345 constant, then return NULL_TREE. */
15347 static tree
15349 {
15352 /* From here on, the only cases we handle are when the result is
15353 known to be a constant. */
15356 {
15360 /* Handle the cases where either operand is a NaN. */
15362 {
15364 {
15392 }
15395 }
15398 }
15401 {
15405 }
15407 /* Handle equality/inequality of complex constants. */
15409 {
15420 else
15422 }
15424 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15426 To compute GT, swap the arguments and do LT.
15427 To compute GE, do LT and invert the result.
15428 To compute LE, swap the arguments, do LT and invert the result.
15429 To compute NE, do EQ and invert the result.
15431 Therefore, the code below must handle only EQ and LT. */
15434 {
15439 }
15441 /* Note that it is safe to invert for real values here because we
15442 have already handled the one case that it matters. */
15446 {
15449 }
15451 /* Compute a result for LT or EQ if args permit;
15452 Otherwise return T. */
15454 {
15459 else
15461 }
15462 else
15468 }
15470 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15471 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15472 itself. */
15474 tree
15476 {
15477 /* If the expression does not have side effects then we don't have to wrap
15478 it with a cleanup point expression. */
15482 /* If the expression is a return, check to see if the expression inside the
15483 return has no side effects or the right hand side of the modify expression
15484 inside the return. If either don't have side effects set we don't need to
15485 wrap the expression in a cleanup point expression. Note we don't check the
15486 left hand side of the modify because it should always be a return decl. */
15488 {
15495 }
15498 }
15500 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15501 of an indirection through OP0, or NULL_TREE if no simplification is
15502 possible. */
15504 tree
15506 {
15508 tree subtype;
15516 {
15519 /* *&CONST_DECL -> to the value of the const decl. */
15522 /* *&p => p; make sure to handle *&"str"[cst] here. */
15524 {
15528 else
15530 }
15531 /* *(foo *)&fooarray => fooarray[0] */
15534 {
15540 }
15541 /* *(foo *)&complexfoo => __real__ complexfoo */
15545 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15548 {
15552 }
15553 }
15555 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15558 {
15561 tree op00type;
15568 {
15579 }
15580 }
15583 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15586 {
15589 tree op00type;
15596 {
15600 }
15601 }
15603 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15606 {
15607 tree type_domain;
15614 }
15617 }
15619 /* Builds an expression for an indirection through T, simplifying some
15620 cases. */
15622 tree
15624 {
15630 else
15632 }
15634 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15636 tree
15638 {
15643 else
15645 }
15647 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15648 whose result is ignored. The type of the returned tree need not be
15649 the same as the original expression. */
15651 tree
15653 {
15659 {
15670 else
15676 {
15692 }
15697 }
15698 }
15700 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15701 This can only be applied to objects of a sizetype. */
15703 tree
15705 {
15712 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15713 have to do anything. Only do this when we are not given a const,
15714 because in that case, this check is more expensive than just
15715 doing it. */
15717 {
15722 }
15724 /* If divisor is a power of two, simplify this to bit manipulation. */
15726 {
15728 {
15741 {
15742 high++;
15745 }
15749 }
15750 else
15751 {
15752 tree t;
15758 }
15759 }
15760 else
15761 {
15766 }
15769 }
15771 /* Likewise, but round down. */
15773 tree
15775 {
15782 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15783 have to do anything. Only do this when we are not given a const,
15784 because in that case, this check is more expensive than just
15785 doing it. */
15787 {
15792 }
15794 /* If divisor is a power of two, simplify this to bit manipulation. */
15796 {
15797 tree t;
15801 }
15802 else
15803 {
15808 }
15811 }
15813 /* Returns the pointer to the base of the object addressed by EXP and
15814 extracts the information about the offset of the access, storing it
15815 to PBITPOS and POFFSET. */
15817 static tree
15820 {
15821 tree core;
15824 HOST_WIDE_INT bitsize;
15827 {
15832 }
15833 else
15834 {
15838 }
15841 }
15843 /* Returns true if addresses of E1 and E2 differ by a constant, false
15844 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15846 bool
15848 {
15862 {
15872 }
15874 {
15875 /* If only one of the offsets is non-constant, the difference cannot
15876 be a constant. */
15878 }
15879 else
15884 }
15886 /* Simplify the floating point expression EXP when the sign of the
15887 result is not significant. Return NULL_TREE if no simplification
15888 is possible. */
15890 tree
15892 {
15896 {
15931 {
15934 {
15936 /* Strip copysign function call, return the 1st argument. */
15942 /* Strip sign ops from the argument of "odd" math functions. */
15944 {
15948 }
15950 }
15951 }
15956 }
15958 }