| blob | e9e3f9b128c9949848099ab06851b7c1d873666e |
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 }
1301 {
1302 /* -(A + B) -> (-B) - A. */
1306 {
1310 }
1312 /* -(A + B) -> (-A) - B. */
1314 {
1318 }
1319 }
1323 /* - (A - B) -> B - A */
1335 /* Fall through. */
1339 {
1348 }
1356 /* In general we can't negate A / B, because if A is INT_MIN and
1357 B is 1, we may turn this into INT_MIN / -1 which is undefined
1358 and actually traps on some architectures. But if overflow is
1359 undefined, we can negate, because - (INT_MIN / 1) is an
1360 overflow. */
1362 {
1367 {
1374 }
1377 {
1384 }
1385 }
1389 /* Convert -((double)float) into (double)(-float). */
1391 {
1395 }
1399 /* Negate -f(x) as f(-x). */
1402 {
1408 }
1412 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1414 {
1419 {
1426 }
1427 }
1432 }
1435 }
1437 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1438 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1439 return NULL_TREE. */
1441 static tree
1443 {
1456 }
1457 \f
1458 /* Split a tree IN into a constant, literal and variable parts that could be
1459 combined with CODE to make IN. "constant" means an expression with
1460 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1461 commutative arithmetic operation. Store the constant part into *CONP,
1462 the literal in *LITP and return the variable part. If a part isn't
1463 present, set it to null. If the tree does not decompose in this way,
1464 return the entire tree as the variable part and the other parts as null.
1466 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1467 case, we negate an operand that was subtracted. Except if it is a
1468 literal for which we use *MINUS_LITP instead.
1470 If NEGATE_P is true, we are negating all of IN, again except a literal
1471 for which we use *MINUS_LITP instead.
1473 If IN is itself a literal or constant, return it as appropriate.
1475 Note that we do not guarantee that any of the three values will be the
1476 same type as IN, but they will have the same signedness and mode. */
1478 static tree
1481 {
1488 /* Strip any conversions that don't change the machine mode or signedness. */
1497 /* We can associate addition and subtraction together (even
1498 though the C standard doesn't say so) for integers because
1499 the value is not affected. For reals, the value might be
1500 affected, so we can't. */
1503 {
1509 /* First see if either of the operands is a literal, then a constant. */
1522 /* If we haven't dealt with either operand, this is not a case we can
1523 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1528 else
1531 /* Now do any needed negations. */
1538 }
1541 else
1545 {
1552 }
1555 }
1557 /* Re-associate trees split by the above function. T1 and T2 are either
1558 expressions to associate or null. Return the new expression, if any. If
1559 we build an operation, do it in TYPE and with CODE. */
1561 static tree
1563 {
1569 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1570 try to fold this since we will have infinite recursion. But do
1571 deal with any NEGATE_EXPRs. */
1574 {
1576 {
1585 }
1587 {
1590 }
1594 }
1598 }
1599 \f
1600 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1601 for use in int_const_binop, size_binop and size_diffop. */
1603 static bool
1605 {
1612 {
1621 }
1626 }
1629 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1630 to produce a new constant. Return NULL_TREE if we don't know how
1631 to evaluate CODE at compile-time.
1633 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1635 tree
1637 {
1641 HOST_WIDE_INT hi;
1643 HOST_WIDE_INT garbageh;
1644 tree t;
1647 int is_sizetype
1657 {
1673 /* It's unclear from the C standard whether shifts can overflow.
1674 The following code ignores overflow; perhaps a C standard
1675 interpretation ruling is needed. */
1707 /* This is a shortcut for a common special case. */
1712 {
1718 }
1720 /* ... fall through ... */
1726 {
1729 }
1732 {
1735 }
1742 /* This is a shortcut for a common special case. */
1747 {
1752 }
1754 /* ... fall through ... */
1772 else
1778 else
1784 }
1787 {
1790 /* Propagate overflow flags ourselves. */
1793 {
1796 }
1797 }
1798 else
1804 }
1806 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1807 constant. We assume ARG1 and ARG2 have the same data type, or at least
1808 are the same kind of constant and the same machine mode. Return zero if
1809 combining the constants is not allowed in the current operating mode.
1811 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1813 static tree
1815 {
1816 /* Sanity check for the recursive cases. */
1827 {
1829 REAL_VALUE_TYPE d1;
1830 REAL_VALUE_TYPE d2;
1831 REAL_VALUE_TYPE value;
1832 REAL_VALUE_TYPE result;
1836 /* The following codes are handled by real_arithmetic. */
1838 {
1849 }
1857 /* Don't perform operation if we honor signaling NaNs and
1858 either operand is a NaN. */
1863 /* Don't perform operation if it would raise a division
1864 by zero exception. */
1870 /* If either operand is a NaN, just return it. Otherwise, set up
1871 for floating-point trap; we return an overflow. */
1880 /* Don't constant fold this floating point operation if
1881 the result has overflowed and flag_trapping_math. */
1889 /* Don't constant fold this floating point operation if the
1890 result may dependent upon the run-time rounding mode and
1891 flag_rounding_math is set, or if GCC's software emulation
1892 is unable to accurately represent the result. */
1902 }
1905 {
1906 FIXED_VALUE_TYPE f1;
1907 FIXED_VALUE_TYPE f2;
1908 FIXED_VALUE_TYPE result;
1913 /* The following codes are handled by fixed_arithmetic. */
1915 {
1932 }
1939 /* Propagate overflow flags. */
1941 {
1944 }
1948 }
1951 {
1960 {
1971 notrunc);
1975 notrunc);
1979 {
1980 tree magsquared
1984 notrunc);
1985 tree t1
1989 notrunc);
1990 tree t2
1994 notrunc);
2001 }
2006 }
2010 }
2013 }
2015 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2016 indicates which particular sizetype to create. */
2018 tree
2020 {
2022 }
2023 \f
2024 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2025 is a tree code. The type of the result is taken from the operands.
2026 Both must be equivalent integer types, ala int_binop_types_match_p.
2027 If the operands are constant, so is the result. */
2029 tree
2031 {
2040 /* Handle the special case of two integer constants faster. */
2042 {
2043 /* And some specific cases even faster than that. */
2045 {
2050 }
2052 {
2055 }
2057 {
2060 }
2062 /* Handle general case of two integer constants. */
2064 }
2067 }
2069 /* Given two values, either both of sizetype or both of bitsizetype,
2070 compute the difference between the two values. Return the value
2071 in signed type corresponding to the type of the operands. */
2073 tree
2075 {
2077 tree ctype;
2082 /* If the type is already signed, just do the simple thing. */
2090 else
2093 /* If either operand is not a constant, do the conversions to the signed
2094 type and subtract. The hardware will do the right thing with any
2095 overflow in the subtraction. */
2100 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2101 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2102 overflow) and negate (which can't either). Special-case a result
2103 of zero while we're here. */
2108 else
2112 }
2113 \f
2114 /* A subroutine of fold_convert_const handling conversions of an
2115 INTEGER_CST to another integer type. */
2117 static tree
2119 {
2120 tree t;
2122 /* Given an integer constant, make new constant with new type,
2123 appropriately sign-extended or truncated. */
2126 /* Don't set the overflow when
2127 converting from a pointer, */
2129 /* or to a sizetype with same signedness
2130 and the precision is unchanged.
2131 ??? sizetype is always sign-extended,
2132 but its signedness depends on the
2133 frontend. Thus we see spurious overflows
2134 here if we do not check this. */
2149 }
2151 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2152 to an integer type. */
2154 static tree
2156 {
2158 tree t;
2160 /* The following code implements the floating point to integer
2161 conversion rules required by the Java Language Specification,
2162 that IEEE NaNs are mapped to zero and values that overflow
2163 the target precision saturate, i.e. values greater than
2164 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2165 are mapped to INT_MIN. These semantics are allowed by the
2166 C and C++ standards that simply state that the behavior of
2167 FP-to-integer conversion is unspecified upon overflow. */
2170 REAL_VALUE_TYPE r;
2174 {
2181 }
2183 /* If R is NaN, return zero and show we have an overflow. */
2185 {
2189 }
2191 /* See if R is less than the lower bound or greater than the
2192 upper bound. */
2195 {
2199 {
2203 }
2204 }
2207 {
2210 {
2213 {
2217 }
2218 }
2219 }
2227 }
2229 /* A subroutine of fold_convert_const handling conversions of a
2230 FIXED_CST to an integer type. */
2232 static tree
2234 {
2235 tree t;
2239 /* Right shift FIXED_CST to temp by fbit. */
2243 {
2248 /* Left shift temp to temp_trunc by fbit. */
2253 }
2254 else
2255 {
2260 }
2262 /* If FIXED_CST is negative, we need to round the value toward 0.
2263 By checking if the fractional bits are not zero to add 1 to temp. */
2266 {
2267 double_int one;
2271 }
2273 /* Given a fixed-point constant, make new constant with new type,
2274 appropriately sign-extended or truncated. */
2282 }
2284 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2285 to another floating point type. */
2287 static tree
2289 {
2290 REAL_VALUE_TYPE value;
2291 tree t;
2298 }
2300 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2301 to a floating point type. */
2303 static tree
2305 {
2306 REAL_VALUE_TYPE value;
2307 tree t;
2316 }
2318 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2319 to another fixed-point type. */
2321 static tree
2323 {
2324 FIXED_VALUE_TYPE value;
2325 tree t;
2332 /* Propagate overflow flags. */
2334 {
2337 }
2341 }
2343 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2344 to a fixed-point type. */
2346 static tree
2348 {
2349 FIXED_VALUE_TYPE value;
2350 tree t;
2359 /* Propagate overflow flags. */
2361 {
2364 }
2368 }
2370 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2371 to a fixed-point type. */
2373 static tree
2375 {
2376 FIXED_VALUE_TYPE value;
2377 tree t;
2385 /* Propagate overflow flags. */
2387 {
2390 }
2394 }
2396 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2397 type TYPE. If no simplification can be done return NULL_TREE. */
2399 static tree
2401 {
2407 {
2414 }
2416 {
2423 }
2425 {
2432 }
2434 }
2436 /* Construct a vector of zero elements of vector type TYPE. */
2438 static tree
2440 {
2451 }
2453 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2455 bool
2457 {
2472 {
2491 }
2492 }
2494 /* Convert expression ARG to type TYPE. Used by the middle-end for
2495 simple conversions in preference to calling the front-end's convert. */
2497 tree
2499 {
2501 tree tem;
2515 {
2520 {
2524 }
2529 {
2532 }
2539 {
2543 }
2545 {
2549 }
2551 {
2555 }
2558 {
2576 }
2581 {
2585 }
2588 {
2602 }
2606 {
2616 {
2620 {
2624 }
2632 }
2636 }
2654 }
2655 }
2656 \f
2657 /* Return false if expr can be assumed not to be an lvalue, true
2658 otherwise. */
2660 static bool
2662 {
2663 /* We only need to wrap lvalue tree codes. */
2665 {
2699 /* Assume the worst for front-end tree codes. */
2703 }
2706 }
2708 /* Return an expr equal to X but certainly not valid as an lvalue. */
2710 tree
2712 {
2713 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2714 us. */
2721 }
2723 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2724 Zero means allow extended lvalues. */
2728 /* When pedantic, return an expr equal to X but certainly not valid as a
2729 pedantic lvalue. Otherwise, return X. */
2731 static tree
2733 {
2736 else
2738 }
2739 \f
2740 /* Given a tree comparison code, return the code that is the logical inverse
2741 of the given code. It is not safe to do this for floating-point
2742 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2743 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2745 enum tree_code
2747 {
2752 {
2783 }
2784 }
2786 /* Similar, but return the comparison that results if the operands are
2787 swapped. This is safe for floating-point. */
2789 enum tree_code
2791 {
2793 {
2819 }
2820 }
2823 /* Convert a comparison tree code from an enum tree_code representation
2824 into a compcode bit-based encoding. This function is the inverse of
2825 compcode_to_comparison. */
2827 static enum comparison_code
2829 {
2831 {
2862 }
2863 }
2865 /* Convert a compcode bit-based encoding of a comparison operator back
2866 to GCC's enum tree_code representation. This function is the
2867 inverse of comparison_to_compcode. */
2869 static enum tree_code
2871 {
2873 {
2904 }
2905 }
2907 /* Return a tree for the comparison which is the combination of
2908 doing the AND or OR (depending on CODE) of the two operations LCODE
2909 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2910 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2911 if this makes the transformation invalid. */
2913 tree
2917 {
2924 {
2935 }
2938 {
2939 /* Eliminate unordered comparisons, as well as LTGT and ORD
2940 which are not used unless the mode has NaNs. */
2946 }
2948 {
2949 /* Check that the original operation and the optimized ones will trap
2950 under the same condition. */
2961 /* In a short-circuited boolean expression the LHS might be
2962 such that the RHS, if evaluated, will never trap. For
2963 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2964 if neither x nor y is NaN. (This is a mixed blessing: for
2965 example, the expression above will never trap, hence
2966 optimizing it to x < y would be invalid). */
2971 /* If the comparison was short-circuited, and only the RHS
2972 trapped, we may now generate a spurious trap. */
2977 /* If we changed the conditions that cause a trap, we lose. */
2980 }
2986 else
2989 }
2990 \f
2991 /* Return nonzero if two operands (typically of the same tree node)
2992 are necessarily equal. If either argument has side-effects this
2993 function returns zero. FLAGS modifies behavior as follows:
2995 If OEP_ONLY_CONST is set, only return nonzero for constants.
2996 This function tests whether the operands are indistinguishable;
2997 it does not test whether they are equal using C's == operation.
2998 The distinction is important for IEEE floating point, because
2999 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3000 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3002 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3003 even though it may hold multiple values during a function.
3004 This is because a GCC tree node guarantees that nothing else is
3005 executed between the evaluation of its "operands" (which may often
3006 be evaluated in arbitrary order). Hence if the operands themselves
3007 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3008 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3009 unset means assuming isochronic (or instantaneous) tree equivalence.
3010 Unless comparing arbitrary expression trees, such as from different
3011 statements, this flag can usually be left unset.
3013 If OEP_PURE_SAME is set, then pure functions with identical arguments
3014 are considered the same. It is used when the caller has other ways
3015 to ensure that global memory is unchanged in between. */
3017 int
3019 {
3020 /* If either is ERROR_MARK, they aren't equal. */
3024 /* Check equality of integer constants before bailing out due to
3025 precision differences. */
3029 /* If both types don't have the same signedness, then we can't consider
3030 them equal. We must check this before the STRIP_NOPS calls
3031 because they may change the signedness of the arguments. As pointers
3032 strictly don't have a signedness, require either two pointers or
3033 two non-pointers as well. */
3038 /* If both types don't have the same precision, then it is not safe
3039 to strip NOPs. */
3046 /* In case both args are comparisons but with different comparison
3047 code, try to swap the comparison operands of one arg to produce
3048 a match and compare that variant. */
3052 {
3060 }
3063 /* This is needed for conversions and for COMPONENT_REF.
3064 Might as well play it safe and always test this. */
3070 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3071 We don't care about side effects in that case because the SAVE_EXPR
3072 takes care of that for us. In all other cases, two expressions are
3073 equal if they have no side effects. If we have two identical
3074 expressions with side effects that should be treated the same due
3075 to the only side effects being identical SAVE_EXPR's, that will
3076 be detected in the recursive calls below. */
3082 /* Next handle constant cases, those for which we can return 1 even
3083 if ONLY_CONST is set. */
3086 {
3101 {
3102 /* If we do not distinguish between signed and unsigned zero,
3103 consider them equal. */
3106 }
3110 {
3116 {
3118 flags))
3122 }
3125 }
3129 flags)
3131 flags));
3144 }
3149 /* Define macros to test an operand from arg0 and arg1 for equality and a
3150 variant that allows null and views null as being different from any
3151 non-null value. In the latter case, if either is null, the both
3152 must be; otherwise, do the normal comparison. */
3153 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3154 TREE_OPERAND (arg1, N), flags)
3156 #define OP_SAME_WITH_NULL(N) \
3157 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3158 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3161 {
3163 /* Two conversions are equal only if signedness and modes match. */
3165 {
3166 CASE_CONVERT:
3174 }
3184 /* For commutative ops, allow the other order. */
3192 /* If either of the pointer (or reference) expressions we are
3193 dereferencing contain a side effect, these cannot be equal. */
3199 {
3209 /* Operands 2 and 3 may be null.
3210 Compare the array index by value if it is constant first as we
3211 may have different types but same value here. */
3220 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3221 may be NULL when we're called to compare MEM_EXPRs. */
3231 }
3235 {
3250 /* Otherwise take into account this is a commutative operation. */
3261 }
3265 {
3267 /* If the CALL_EXPRs call different functions, then they
3268 clearly can not be equal. */
3270 flags))
3273 {
3277 else
3281 }
3283 /* Now see if all the arguments are the same. */
3284 {
3295 /* If we get here and both argument lists are exhausted
3296 then the CALL_EXPRs are equal. */
3298 }
3301 }
3304 /* Consider __builtin_sqrt equal to sqrt. */
3312 }
3314 #undef OP_SAME
3315 #undef OP_SAME_WITH_NULL
3316 }
3317 \f
3318 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3319 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3321 When in doubt, return 0. */
3323 static int
3325 {
3337 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3338 and see if the inner values are the same. This removes any
3339 signedness comparison, which doesn't matter here. */
3346 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3347 actual comparison operand, ARG0.
3349 First throw away any conversions to wider types
3350 already present in the operands. */
3359 {
3362 /* Make sure shorter operand is extended the right way
3363 to match the longer operand. */
3369 }
3372 }
3373 \f
3374 /* See if ARG is an expression that is either a comparison or is performing
3375 arithmetic on comparisons. The comparisons must only be comparing
3376 two different values, which will be stored in *CVAL1 and *CVAL2; if
3377 they are nonzero it means that some operands have already been found.
3378 No variables may be used anywhere else in the expression except in the
3379 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3380 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3382 If this is true, return 1. Otherwise, return zero. */
3384 static int
3386 {
3390 /* We can handle some of the tcc_expression cases here. */
3400 {
3401 /* If we've already found a CVAL1 or CVAL2, this expression is
3402 two complex to handle. */
3408 }
3411 {
3434 /* First see if we can handle the first operand, then the second. For
3435 the second operand, we know *CVAL1 can't be zero. It must be that
3436 one side of the comparison is each of the values; test for the
3437 case where this isn't true by failing if the two operands
3438 are the same. */
3447 ;
3451 ;
3452 else
3456 ;
3460 ;
3461 else
3468 }
3469 }
3470 \f
3471 /* ARG is a tree that is known to contain just arithmetic operations and
3472 comparisons. Evaluate the operations in the tree substituting NEW0 for
3473 any occurrence of OLD0 as an operand of a comparison and likewise for
3474 NEW1 and OLD1. */
3476 static tree
3478 {
3483 /* We can handle some of the tcc_expression cases here. */
3491 {
3506 {
3523 }
3524 /* Fall through - ??? */
3527 {
3531 /* We need to check both for exact equality and tree equality. The
3532 former will be true if the operand has a side-effect. In that
3533 case, we know the operand occurred exactly once. */
3546 }
3550 }
3551 }
3552 \f
3553 /* Return a tree for the case when the result of an expression is RESULT
3554 converted to TYPE and OMITTED was previously an operand of the expression
3555 but is now not needed (e.g., we folded OMITTED * 0).
3557 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3558 the conversion of RESULT to TYPE. */
3560 tree
3562 {
3565 /* If the resulting operand is an empty statement, just return the omitted
3566 statement casted to void. */
3574 }
3576 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3578 static tree
3580 {
3583 /* If the resulting operand is an empty statement, just return the omitted
3584 statement casted to void. */
3592 }
3594 /* Return a tree for the case when the result of an expression is RESULT
3595 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3596 of the expression but are now not needed.
3598 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3599 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3600 evaluated before OMITTED2. Otherwise, if neither has side effects,
3601 just do the conversion of RESULT to TYPE. */
3603 tree
3605 {
3614 }
3616 \f
3617 /* Return a simplified tree node for the truth-negation of ARG. This
3618 never alters ARG itself. We assume that ARG is an operation that
3619 returns a truth value (0 or 1).
3621 FIXME: one would think we would fold the result, but it causes
3622 problems with the dominator optimizer. */
3624 tree
3626 {
3630 /* If this is a comparison, we can simply invert it, except for
3631 floating-point non-equality comparisons, in which case we just
3632 enclose a TRUTH_NOT_EXPR around what we have. */
3635 {
3638 && flag_trapping_math
3642 else
3643 {
3648 else
3651 }
3652 }
3655 {
3670 /* Here we can invert either operand. We invert the first operand
3671 unless the second operand is a TRUTH_NOT_EXPR in which case our
3672 result is the XOR of the first operand with the inside of the
3673 negation of the second operand. */
3678 else
3697 {
3700 /* A COND_EXPR may have a throw as one operand, which
3701 then has void type. Just leave void operands
3702 as they are. */
3708 }
3741 }
3744 }
3746 /* Return a simplified tree node for the truth-negation of ARG. This
3747 never alters ARG itself. We assume that ARG is an operation that
3748 returns a truth value (0 or 1).
3750 FIXME: one would think we would fold the result, but it causes
3751 problems with the dominator optimizer. */
3753 tree
3755 {
3756 tree tem;
3766 }
3768 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3769 operands are another bit-wise operation with a common input. If so,
3770 distribute the bit operations to save an operation and possibly two if
3771 constants are involved. For example, convert
3772 (A | B) & (A | C) into A | (B & C)
3773 Further simplification will occur if B and C are constants.
3775 If this optimization cannot be done, 0 will be returned. */
3777 static tree
3779 {
3780 tree common;
3790 {
3794 }
3796 {
3800 }
3802 {
3806 }
3808 {
3812 }
3813 else
3821 }
3823 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3824 with code CODE. This optimization is unsafe. */
3825 static tree
3827 {
3831 /* (A / C) +- (B / C) -> (A +- B) / C. */
3841 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3846 {
3858 }
3861 }
3862 \f
3863 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3864 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3866 static tree
3869 {
3873 {
3880 }
3894 }
3896 /* Optimize a bit-field compare.
3898 There are two cases: First is a compare against a constant and the
3899 second is a comparison of two items where the fields are at the same
3900 bit position relative to the start of a chunk (byte, halfword, word)
3901 large enough to contain it. In these cases we can avoid the shift
3902 implicit in bitfield extractions.
3904 For constants, we emit a compare of the shifted constant with the
3905 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3906 compared. For two fields at the same position, we do the ANDs with the
3907 similar mask and compare the result of the ANDs.
3909 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3910 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3911 are the left and right operands of the comparison, respectively.
3913 If the optimization described above can be done, we return the resulting
3914 tree. Otherwise we return zero. */
3916 static tree
3919 {
3928 tree mask;
3929 tree offset;
3931 /* Get all the information about the extractions being done. If the bit size
3932 if the same as the size of the underlying object, we aren't doing an
3933 extraction at all and so can do nothing. We also don't want to
3934 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3935 then will no longer be able to replace it. */
3943 {
3944 /* If this is not a constant, we can only do something if bit positions,
3945 sizes, and signedness are the same. */
3953 }
3955 /* See if we can find a mode to refer to this field. We should be able to,
3956 but fail if we can't. */
3965 /* Set signed and unsigned types of the precision of this mode for the
3966 shifts below. */
3970 /* Compute the bit position and size for the new reference and our offset
3971 within it. If the new reference is the same size as the original, we
3972 won't optimize anything, so return zero. */
3982 /* Make the mask to be used against the extracted field. */
3989 /* If not comparing with constant, just rework the comparison
3990 and return. */
3994 unsigned_type,
3997 mask),
4000 unsigned_type,
4003 mask));
4005 /* Otherwise, we are handling the constant case. See if the constant is too
4006 big for the field. Warn and return a tree of for 0 (false) if so. We do
4007 this not only for its own sake, but to avoid having to test for this
4008 error case below. If we didn't, we might generate wrong code.
4010 For unsigned fields, the constant shifted right by the field length should
4011 be all zero. For signed fields, the high-order bits should agree with
4012 the sign bit. */
4015 {
4019 {
4023 }
4024 }
4025 else
4026 {
4030 {
4034 }
4035 }
4037 /* Single-bit compares should always be against zero. */
4039 {
4042 }
4044 /* Make a new bitfield reference, shift the constant over the
4045 appropriate number of bits and mask it with the computed mask
4046 (in case this was a signed field). If we changed it, make a new one. */
4049 {
4052 }
4062 rhs);
4063 }
4064 \f
4065 /* Subroutine for fold_truthop: decode a field reference.
4067 If EXP is a comparison reference, we return the innermost reference.
4069 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4070 set to the starting bit number.
4072 If the innermost field can be completely contained in a mode-sized
4073 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4075 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4076 otherwise it is not changed.
4078 *PUNSIGNEDP is set to the signedness of the field.
4080 *PMASK is set to the mask used. This is either contained in a
4081 BIT_AND_EXPR or derived from the width of the field.
4083 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4085 Return 0 if this is not a component reference or is one that we can't
4086 do anything with. */
4088 static tree
4093 {
4097 tree unsigned_type;
4100 /* All the optimizations using this function assume integer fields.
4101 There are problems with FP fields since the type_for_size call
4102 below can fail for, e.g., XFmode. */
4106 /* We are interested in the bare arrangement of bits, so strip everything
4107 that doesn't affect the machine mode. However, record the type of the
4108 outermost expression if it may matter below. */
4115 {
4121 }
4130 /* If the number of bits in the reference is the same as the bitsize of
4131 the outer type, then the outer type gives the signedness. Otherwise
4132 (in case of a small bitfield) the signedness is unchanged. */
4136 /* Compute the mask to access the bitfield. */
4145 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4153 }
4155 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4156 bit positions. */
4158 static int
4160 {
4163 tree tmask;
4167 return
4174 }
4176 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4177 represents the sign bit of EXP's type. If EXP represents a sign
4178 or zero extension, also test VAL against the unextended type.
4179 The return value is the (sub)expression whose sign bit is VAL,
4180 or NULL_TREE otherwise. */
4182 static tree
4184 {
4188 tree t;
4190 /* Tree EXP must have an integral type. */
4195 /* Tree VAL must be an integer constant. */
4202 {
4209 }
4210 else
4211 {
4218 }
4220 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4221 treat VAL as if it were unsigned. */
4226 /* Handle extension from a narrower type. */
4232 }
4234 /* Subroutine for fold_truthop: determine if an operand is simple enough
4235 to be evaluated unconditionally. */
4237 static int
4239 {
4240 /* Strip any conversions that don't change the machine mode. */
4249 /* Don't regard global variables as simple. They may be
4250 allocated in ways unknown to the compiler (shared memory,
4251 #pragma weak, etc). */
4254 /* Loading a static variable is unduly expensive, but global
4255 registers aren't expensive. */
4257 }
4258 \f
4259 /* The following functions are subroutines to fold_range_test and allow it to
4260 try to change a logical combination of comparisons into a range test.
4262 For example, both
4263 X == 2 || X == 3 || X == 4 || X == 5
4264 and
4265 X >= 2 && X <= 5
4266 are converted to
4267 (unsigned) (X - 2) <= 3
4269 We describe each set of comparisons as being either inside or outside
4270 a range, using a variable named like IN_P, and then describe the
4271 range with a lower and upper bound. If one of the bounds is omitted,
4272 it represents either the highest or lowest value of the type.
4274 In the comments below, we represent a range by two numbers in brackets
4275 preceded by a "+" to designate being inside that range, or a "-" to
4276 designate being outside that range, so the condition can be inverted by
4277 flipping the prefix. An omitted bound is represented by a "-". For
4278 example, "- [-, 10]" means being outside the range starting at the lowest
4279 possible value and ending at 10, in other words, being greater than 10.
4280 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4281 always false.
4283 We set up things so that the missing bounds are handled in a consistent
4284 manner so neither a missing bound nor "true" and "false" need to be
4285 handled using a special case. */
4287 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4288 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4289 and UPPER1_P are nonzero if the respective argument is an upper bound
4290 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4291 must be specified for a comparison. ARG1 will be converted to ARG0's
4292 type if both are specified. */
4294 static tree
4297 {
4298 tree tem;
4302 /* If neither arg represents infinity, do the normal operation.
4303 Else, if not a comparison, return infinity. Else handle the special
4304 comparison rules. Note that most of the cases below won't occur, but
4305 are handled for consistency. */
4308 {
4313 }
4318 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4319 for neither. In real maths, we cannot assume open ended ranges are
4320 the same. But, this is computer arithmetic, where numbers are finite.
4321 We can therefore make the transformation of any unbounded range with
4322 the value Z, Z being greater than any representable number. This permits
4323 us to treat unbounded ranges as equal. */
4327 {
4348 }
4351 }
4352 \f
4353 /* Given EXP, a logical expression, set the range it is testing into
4354 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4355 actually being tested. *PLOW and *PHIGH will be made of the same
4356 type as the returned expression. If EXP is not a comparison, we
4357 will most likely not be returning a useful value and range. Set
4358 *STRICT_OVERFLOW_P to true if the return value is only valid
4359 because signed overflow is undefined; otherwise, do not change
4360 *STRICT_OVERFLOW_P. */
4362 static tree
4365 {
4372 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4373 and see if we can refine the range. Some of the cases below may not
4374 happen, but it doesn't seem worth worrying about this. We "continue"
4375 the outer loop when we've changed something; otherwise we "break"
4376 the switch, which will "break" the while. */
4382 {
4387 {
4399 }
4402 {
4409 /* We can only do something if the range is testing for zero
4410 and if the second operand is an integer constant. Note that
4411 saying something is "in" the range we make is done by
4412 complementing IN_P since it will set in the initial case of
4413 being not equal to zero; "out" is leaving it alone. */
4420 {
4441 }
4443 /* If this is an unsigned comparison, we also know that EXP is
4444 greater than or equal to zero. We base the range tests we make
4445 on that fact, so we record it here so we can parse existing
4446 range tests. We test arg0_type since often the return type
4447 of, e.g. EQ_EXPR, is boolean. */
4449 {
4453 NULL_TREE))
4458 /* If the high bound is missing, but we have a nonzero low
4459 bound, reverse the range so it goes from zero to the low bound
4460 minus 1. */
4462 {
4467 }
4468 }
4474 /* (-x) IN [a,b] -> x in [-b, -a] */
4486 /* ~ X -> -X - 1 */
4495 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4496 move a constant to the other side. */
4501 /* If EXP is signed, any overflow in the computation is undefined,
4502 so we don't worry about it so long as our computations on
4503 the bounds don't overflow. For unsigned, overflow is defined
4504 and this is exactly the right thing. */
4516 /* Check for an unsigned range which has wrapped around the maximum
4517 value thus making n_high < n_low, and normalize it. */
4519 {
4525 /* If the range is of the form +/- [ x+1, x ], we won't
4526 be able to normalize it. But then, it represents the
4527 whole range or the empty set, so make it
4528 +/- [ -, - ]. */
4532 else
4534 }
4535 else
4559 /* If we're converting arg0 from an unsigned type, to exp,
4560 a signed type, we will be doing the comparison as unsigned.
4561 The tests above have already verified that LOW and HIGH
4562 are both positive.
4564 So we have to ensure that we will handle large unsigned
4565 values the same way that the current signed bounds treat
4566 negative values. */
4569 {
4570 tree high_positive;
4571 tree equiv_type;
4572 /* For fixed-point modes, we need to pass the saturating flag
4573 as the 2nd parameter. */
4578 else
4582 /* A range without an upper bound is, naturally, unbounded.
4583 Since convert would have cropped a very large value, use
4584 the max value for the destination type. */
4585 high_positive
4592 high_positive),
4595 /* If the low bound is specified, "and" the range with the
4596 range for which the original unsigned value will be
4597 positive. */
4599 {
4603 integer_zero_node),
4604 high_positive))
4608 }
4609 else
4610 {
4611 /* Otherwise, "or" the range with the range of the input
4612 that will be interpreted as negative. */
4616 integer_zero_node),
4617 high_positive))
4621 }
4622 }
4630 }
4633 }
4635 /* If EXP is a constant, we can evaluate whether this is true or false. */
4637 {
4644 }
4648 }
4649 \f
4650 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4651 type, TYPE, return an expression to test if EXP is in (or out of, depending
4652 on IN_P) the range. Return 0 if the test couldn't be created. */
4654 static tree
4656 {
4658 tree value;
4660 #ifdef HAVE_canonicalize_funcptr_for_compare
4661 /* Disable this optimization for function pointer expressions
4662 on targets that require function pointer canonicalization. */
4667 #endif
4670 {
4676 }
4694 {
4696 {
4700 }
4702 }
4704 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4706 {
4708 HOST_WIDE_INT hi;
4713 {
4716 }
4717 else
4718 {
4721 }
4724 {
4726 {
4729 etype
4731 else
4734 }
4737 }
4738 }
4740 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4741 This requires wrap-around arithmetics for the type of the expression. */
4743 {
4745 /* There is no requirement that LOW be within the range of ETYPE
4746 if the latter is a subtype. It must, however, be within the base
4747 type of ETYPE. So be sure we do the subtraction in that type. */
4760 }
4762 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4765 {
4768 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4769 for the type in question, as we rely on this here. */
4779 else
4781 }
4791 {
4793 {
4799 }
4801 }
4809 }
4810 \f
4811 /* Return the predecessor of VAL in its type, handling the infinite case. */
4813 static tree
4815 {
4821 else
4823 }
4825 /* Return the successor of VAL in its type, handling the infinite case. */
4827 static tree
4829 {
4835 else
4837 }
4839 /* Given two ranges, see if we can merge them into one. Return 1 if we
4840 can, 0 if we can't. Set the output range into the specified parameters. */
4842 static int
4845 {
4849 tree tem;
4859 /* Make range 0 be the range that starts first, or ends last if they
4860 start at the same value. Swap them if it isn't. */
4863 || (lowequal
4866 {
4870 }
4872 /* Now flag two cases, whether the ranges are disjoint or whether the
4873 second range is totally subsumed in the first. Note that the tests
4874 below are simplified by the ones above. */
4880 /* We now have four cases, depending on whether we are including or
4881 excluding the two ranges. */
4883 {
4884 /* If they don't overlap, the result is false. If the second range
4885 is a subset it is the result. Otherwise, the range is from the start
4886 of the second to the end of the first. */
4891 else
4893 }
4896 {
4897 /* If they don't overlap, the result is the first range. If they are
4898 equal, the result is false. If the second range is a subset of the
4899 first, and the ranges begin at the same place, we go from just after
4900 the end of the second range to the end of the first. If the second
4901 range is not a subset of the first, or if it is a subset and both
4902 ranges end at the same place, the range starts at the start of the
4903 first range and ends just before the second range.
4904 Otherwise, we can't describe this as a single range. */
4910 {
4915 {
4916 /* We are in the weird situation where high0 > high1 but
4917 high1 has no successor. Punt. */
4919 }
4920 }
4922 {
4927 {
4928 /* low0 < low1 but low1 has no predecessor. Punt. */
4930 }
4931 }
4932 else
4934 }
4937 {
4938 /* If they don't overlap, the result is the second range. If the second
4939 is a subset of the first, the result is false. Otherwise,
4940 the range starts just after the first range and ends at the
4941 end of the second. */
4946 else
4947 {
4952 {
4953 /* high1 > high0 but high0 has no successor. Punt. */
4955 }
4956 }
4957 }
4959 else
4960 {
4961 /* The case where we are excluding both ranges. Here the complex case
4962 is if they don't overlap. In that case, the only time we have a
4963 range is if they are adjacent. If the second is a subset of the
4964 first, the result is the first. Otherwise, the range to exclude
4965 starts at the beginning of the first range and ends at the end of the
4966 second. */
4968 {
4973 else
4974 {
4975 /* Canonicalize - [min, x] into - [-, x]. */
4978 {
4983 /* FALLTHROUGH */
4996 }
4998 /* Canonicalize - [x, max] into - [x, -]. */
5001 {
5006 /* FALLTHROUGH */
5021 }
5023 /* The ranges might be also adjacent between the maximum and
5024 minimum values of the given type. For
5025 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5026 return + [x + 1, y - 1]. */
5028 {
5035 }
5036 else
5038 }
5039 }
5042 else
5044 }
5048 }
5049 \f
5051 /* Subroutine of fold, looking inside expressions of the form
5052 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5053 of the COND_EXPR. This function is being used also to optimize
5054 A op B ? C : A, by reversing the comparison first.
5056 Return a folded expression whose code is not a COND_EXPR
5057 anymore, or NULL_TREE if no folding opportunity is found. */
5059 static tree
5061 {
5066 tree tem;
5071 /* If we have A op 0 ? A : -A, consider applying the following
5072 transformations:
5074 A == 0? A : -A same as -A
5075 A != 0? A : -A same as A
5076 A >= 0? A : -A same as abs (A)
5077 A > 0? A : -A same as abs (A)
5078 A <= 0? A : -A same as -abs (A)
5079 A < 0? A : -A same as -abs (A)
5081 None of these transformations work for modes with signed
5082 zeros. If A is +/-0, the first two transformations will
5083 change the sign of the result (from +0 to -0, or vice
5084 versa). The last four will fix the sign of the result,
5085 even though the original expressions could be positive or
5086 negative, depending on the sign of A.
5088 Note that all these transformations are correct if A is
5089 NaN, since the two alternatives (A and -A) are also NaNs. */
5096 /* In the case that A is of the form X-Y, '-A' (arg2) may
5097 have already been folded to Y-X, check for that. */
5105 {
5117 /* Fall through. */
5139 }
5141 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5142 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5143 both transformations are correct when A is NaN: A != 0
5144 is then true, and A == 0 is false. */
5148 {
5153 }
5155 /* Try some transformations of A op B ? A : B.
5157 A == B? A : B same as B
5158 A != B? A : B same as A
5159 A >= B? A : B same as max (A, B)
5160 A > B? A : B same as max (B, A)
5161 A <= B? A : B same as min (A, B)
5162 A < B? A : B same as min (B, A)
5164 As above, these transformations don't work in the presence
5165 of signed zeros. For example, if A and B are zeros of
5166 opposite sign, the first two transformations will change
5167 the sign of the result. In the last four, the original
5168 expressions give different results for (A=+0, B=-0) and
5169 (A=-0, B=+0), but the transformed expressions do not.
5171 The first two transformations are correct if either A or B
5172 is a NaN. In the first transformation, the condition will
5173 be false, and B will indeed be chosen. In the case of the
5174 second transformation, the condition A != B will be true,
5175 and A will be chosen.
5177 The conversions to max() and min() are not correct if B is
5178 a number and A is not. The conditions in the original
5179 expressions will be false, so all four give B. The min()
5180 and max() versions would give a NaN instead. */
5183 /* Avoid these transformations if the COND_EXPR may be used
5184 as an lvalue in the C++ front-end. PR c++/19199. */
5185 && (in_gimple_form
5190 {
5195 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5197 {
5201 }
5204 {
5213 /* In C++ a ?: expression can be an lvalue, so put the
5214 operand which will be used if they are equal first
5215 so that we can convert this back to the
5216 corresponding COND_EXPR. */
5218 {
5225 }
5232 {
5239 }
5252 }
5253 }
5255 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5256 we might still be able to simplify this. For example,
5257 if C1 is one less or one more than C2, this might have started
5258 out as a MIN or MAX and been transformed by this function.
5259 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5265 {
5267 /* We can replace A with C1 in this case. */
5272 /* If C1 is C2 + 1, this is min(A, C2). */
5274 OEP_ONLY_CONST)
5278 OEP_ONLY_CONST))
5280 type,
5282 arg2));
5286 /* If C1 is C2 - 1, this is min(A, C2). */
5288 OEP_ONLY_CONST)
5292 OEP_ONLY_CONST))
5294 type,
5296 arg2));
5300 /* If C1 is C2 - 1, this is max(A, C2). */
5302 OEP_ONLY_CONST)
5306 OEP_ONLY_CONST))
5308 type,
5310 arg2));
5314 /* If C1 is C2 + 1, this is max(A, C2). */
5316 OEP_ONLY_CONST)
5320 OEP_ONLY_CONST))
5322 type,
5324 arg2));
5330 }
5333 }
5336 \f
5337 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5338 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5339 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5340 false) >= 2)
5341 #endif
5343 /* EXP is some logical combination of boolean tests. See if we can
5344 merge it into some range test. Return the new tree if so. */
5346 static tree
5348 {
5356 tree tem;
5360 /* If this is an OR operation, invert both sides; we will invert
5361 again at the end. */
5365 /* If both expressions are the same, if we can merge the ranges, and we
5366 can build the range test, return it or it inverted. If one of the
5367 ranges is always true or always false, consider it to be the same
5368 expression as the other. */
5376 {
5380 }
5382 /* On machines where the branch cost is expensive, if this is a
5383 short-circuited branch and the underlying object on both sides
5384 is the same, make a non-short-circuit operation. */
5390 {
5391 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5392 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5393 which cases we can't do this. */
5401 {
5410 {
5413 WARN_STRICT_OVERFLOW_COMPARISON);
5417 }
5418 }
5419 }
5422 }
5423 \f
5424 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5425 bit value. Arrange things so the extra bits will be set to zero if and
5426 only if C is signed-extended to its full width. If MASK is nonzero,
5427 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5429 static tree
5431 {
5434 tree temp;
5439 /* We work by getting just the sign bit into the low-order bit, then
5440 into the high-order bit, then sign-extend. We then XOR that value
5441 with C. */
5445 /* We must use a signed type in order to get an arithmetic right shift.
5446 However, we must also avoid introducing accidental overflows, so that
5447 a subsequent call to integer_zerop will work. Hence we must
5448 do the type conversion here. At this point, the constant is either
5449 zero or one, and the conversion to a signed type can never overflow.
5450 We could get an overflow if this conversion is done anywhere else. */
5459 /* If necessary, convert the type back to match the type of C. */
5464 }
5465 \f
5466 /* Find ways of folding logical expressions of LHS and RHS:
5467 Try to merge two comparisons to the same innermost item.
5468 Look for range tests like "ch >= '0' && ch <= '9'".
5469 Look for combinations of simple terms on machines with expensive branches
5470 and evaluate the RHS unconditionally.
5472 For example, if we have p->a == 2 && p->b == 4 and we can make an
5473 object large enough to span both A and B, we can do this with a comparison
5474 against the object ANDed with the a mask.
5476 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5477 operations to do this with one comparison.
5479 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5480 function and the one above.
5482 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5483 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5485 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5486 two operands.
5488 We return the simplified tree or 0 if no optimization is possible. */
5490 static tree
5492 {
5493 /* If this is the "or" of two comparisons, we can do something if
5494 the comparisons are NE_EXPR. If this is the "and", we can do something
5495 if the comparisons are EQ_EXPR. I.e.,
5496 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5498 WANTED_CODE is this operation code. For single bit fields, we can
5499 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5500 comparison for one-bit fields. */
5522 /* Start by getting the comparison codes. Fail if anything is volatile.
5523 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5524 it were surrounded with a NE_EXPR. */
5533 {
5537 }
5540 {
5544 }
5555 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5558 {
5559 tree result;
5562 {
5567 }
5570 {
5576 }
5577 }
5582 /* If the RHS can be evaluated unconditionally and its operands are
5583 simple, it wins to evaluate the RHS unconditionally on machines
5584 with expensive branches. In this case, this isn't a comparison
5585 that can be merged. Avoid doing this if the RHS is a floating-point
5586 comparison since those can trap. */
5593 {
5594 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5605 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5617 {
5621 }
5622 }
5624 /* See if the comparisons can be merged. Then get all the parameters for
5625 each side. */
5649 /* It must be true that the inner operation on the lhs of each
5650 comparison must be the same if we are to be able to do anything.
5651 Then see if we have constants. If not, the same must be true for
5652 the rhs's. */
5663 else
5666 /* If either comparison code is not correct for our logical operation,
5667 fail. However, we can convert a one-bit comparison against zero into
5668 the opposite comparison against that bit being set in the field. */
5672 {
5674 {
5675 /* Make the left operand unsigned, since we are only interested
5676 in the value of one bit. Otherwise we are doing the wrong
5677 thing below. */
5680 }
5681 else
5683 }
5685 /* This is analogous to the code for l_const above. */
5687 {
5689 {
5692 }
5693 else
5695 }
5697 /* See if we can find a mode that contains both fields being compared on
5698 the left. If we can't, fail. Otherwise, update all constants and masks
5699 to be relative to a field of that size. */
5704 volatilep);
5714 {
5717 }
5725 {
5733 {
5737 }
5738 }
5740 {
5748 {
5752 }
5753 }
5755 /* If the right sides are not constant, do the same for it. Also,
5756 disallow this optimization if a size or signedness mismatch occurs
5757 between the left and right sides. */
5759 {
5762 /* Make sure the two fields on the right
5763 correspond to the left without being swapped. */
5771 volatilep);
5781 {
5784 }
5791 /* Make a mask that corresponds to both fields being compared.
5792 Do this for both items being compared. If the operands are the
5793 same size and the bits being compared are in the same position
5794 then we can do this by masking both and comparing the masked
5795 results. */
5799 {
5811 }
5813 /* There is still another way we can do something: If both pairs of
5814 fields being compared are adjacent, we may be able to make a wider
5815 field containing them both.
5817 Note that we still must mask the lhs/rhs expressions. Furthermore,
5818 the mask must be shifted to account for the shift done by
5819 make_bit_field_ref. */
5824 {
5825 tree type;
5837 /* Convert to the smaller type before masking out unwanted bits. */
5840 {
5842 {
5846 }
5848 {
5852 }
5853 }
5862 }
5865 }
5867 /* Handle the case of comparisons with constants. If there is something in
5868 common between the masks, those bits of the constants must be the same.
5869 If not, the condition is always false. Test for this to avoid generating
5870 incorrect code below. */
5875 {
5877 {
5880 }
5881 else
5882 {
5885 }
5886 }
5888 /* Construct the expression we will return. First get the component
5889 reference we will make. Unless the mask is all ones the width of
5890 that field, perform the mask operation. Then compare with the
5891 merged constant. */
5901 }
5902 \f
5903 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5904 constant. */
5906 static tree
5908 {
5911 tree comp_const;
5912 tree minmax_const;
5914 tree inner;
5925 /* If something does not permit us to optimize, return the original tree. */
5933 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5934 and GT_EXPR, doing the rest with recursive calls using logical
5935 simplifications. */
5937 {
5939 {
5945 }
5948 return
5950 optimize_minmax_comparison
5952 optimize_minmax_comparison
5957 /* MAX (X, 0) == 0 -> X <= 0 */
5961 /* MAX (X, 0) == 5 -> X == 5 */
5965 /* MAX (X, 0) == -1 -> false */
5969 /* MIN (X, 0) == 0 -> X >= 0 */
5973 /* MIN (X, 0) == 5 -> false */
5976 else
5977 /* MIN (X, 0) == -1 -> X == -1 */
5982 /* MAX (X, 0) > 0 -> X > 0
5983 MAX (X, 0) > 5 -> X > 5 */
5987 /* MAX (X, 0) > -1 -> true */
5991 /* MIN (X, 0) > 0 -> false
5992 MIN (X, 0) > 5 -> false */
5995 else
5996 /* MIN (X, 0) > -1 -> X > -1 */
6001 }
6002 }
6003 \f
6004 /* T is an integer expression that is being multiplied, divided, or taken a
6005 modulus (CODE says which and what kind of divide or modulus) by a
6006 constant C. See if we can eliminate that operation by folding it with
6007 other operations already in T. WIDE_TYPE, if non-null, is a type that
6008 should be used for the computation if wider than our type.
6010 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6011 (X * 2) + (Y * 4). We must, however, be assured that either the original
6012 expression would not overflow or that overflow is undefined for the type
6013 in the language in question.
6015 If we return a non-null expression, it is an equivalent form of the
6016 original computation, but need not be in the original type.
6018 We set *STRICT_OVERFLOW_P to true if the return values depends on
6019 signed overflow being undefined. Otherwise we do not change
6020 *STRICT_OVERFLOW_P. */
6022 static tree
6025 {
6026 /* To avoid exponential search depth, refuse to allow recursion past
6027 three levels. Beyond that (1) it's highly unlikely that we'll find
6028 something interesting and (2) we've probably processed it before
6029 when we built the inner expression. */
6032 tree ret;
6037 depth++;
6039 depth--;
6042 }
6044 static tree
6047 {
6058 /* Don't deal with constants of zero here; they confuse the code below. */
6068 /* Note that we need not handle conditional operations here since fold
6069 already handles those cases. So just do arithmetic here. */
6071 {
6073 /* For a constant, we can always simplify if we are a multiply
6074 or (for divide and modulus) if it is a multiple of our constant. */
6082 /* If op0 is an expression ... */
6088 /* ... and has wrapping overflow, and its type is smaller
6089 than ctype, then we cannot pass through as widening. */
6095 /* ... or this is a truncation (t is narrower than op0),
6096 then we cannot pass through this narrowing. */
6099 /* ... or signedness changes for division or modulus,
6100 then we cannot pass through this conversion. */
6104 /* ... or has undefined overflow while the converted to
6105 type has not, we cannot do the operation in the inner type
6106 as that would introduce undefined overflow. */
6111 /* Pass the constant down and see if we can make a simplification. If
6112 we can, replace this expression with the inner simplification for
6113 possible later conversion to our or some other type. */
6118 code == MULT_EXPR
6120 strict_overflow_p))))
6125 /* If widening the type changes it from signed to unsigned, then we
6126 must avoid building ABS_EXPR itself as unsigned. */
6128 {
6132 {
6135 }
6137 }
6138 /* If the constant is negative, we cannot simplify this. */
6141 /* FALLTHROUGH */
6149 /* If widening the type changes the signedness, then we can't perform
6150 this optimization as that changes the result. */
6154 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6160 {
6167 }
6171 /* If the second operand is constant, this is a multiplication
6172 or floor division, by a power of two, so we can treat it that
6173 way unless the multiplier or divisor overflows. Signed
6174 left-shift overflow is implementation-defined rather than
6175 undefined in C90, so do not convert signed left shift into
6176 multiplication. */
6179 /* const_binop may not detect overflow correctly,
6180 so check for it explicitly here. */
6185 size_one_node,
6195 /* See if we can eliminate the operation on both sides. If we can, we
6196 can return a new PLUS or MINUS. If we can't, the only remaining
6197 cases where we can do anything are if the second operand is a
6198 constant. */
6204 /* If not multiplication, we can only do this if both operands
6205 are divisible by c. */
6208 {
6213 }
6215 /* If this was a subtraction, negate OP1 and set it to be an addition.
6216 This simplifies the logic below. */
6223 /* If either OP1 or C are negative, this optimization is not safe for
6224 some of the division and remainder types while for others we need
6225 to change the code. */
6227 {
6235 }
6237 /* If it's a multiply or a division/modulus operation of a multiple
6238 of our constant, do the operation and verify it doesn't overflow. */
6241 {
6244 /* We allow the constant to overflow with wrapping semantics. */
6248 }
6249 else
6252 /* If we have an unsigned type is not a sizetype, we cannot widen
6253 the operation since it will change the result if the original
6254 computation overflowed. */
6260 /* If we were able to eliminate our operation from the first side,
6261 apply our operation to the second side and reform the PLUS. */
6265 /* The last case is if we are a multiply. In that case, we can
6266 apply the distributive law to commute the multiply and addition
6267 if the multiplication of the constants doesn't overflow. */
6273 op1);
6278 /* We have a special case here if we are doing something like
6279 (C * 8) % 4 since we know that's zero. */
6282 /* If the multiplication can overflow we cannot optimize this.
6283 ??? Until we can properly mark individual operations as
6284 not overflowing we need to treat sizetype special here as
6285 stor-layout relies on this opimization to make
6286 DECL_FIELD_BIT_OFFSET always a constant. */
6292 {
6295 }
6297 /* ... fall through ... */
6301 /* If we can extract our operation from the LHS, do so and return a
6302 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6303 do something only if the second operand is a constant. */
6317 /* If these are the same operation types, we can associate them
6318 assuming no overflow. */
6330 /* If these operations "cancel" each other, we have the main
6331 optimizations of this pass, which occur when either constant is a
6332 multiple of the other, in which case we replace this with either an
6333 operation or CODE or TCODE.
6335 If we have an unsigned type that is not a sizetype, we cannot do
6336 this since it will change the result if the original computation
6337 overflowed. */
6345 {
6347 {
6354 }
6356 {
6363 }
6364 }
6369 }
6372 }
6373 \f
6374 /* Return a node which has the indicated constant VALUE (either 0 or
6375 1), and is of the indicated TYPE. */
6377 tree
6379 {
6384 else
6386 }
6389 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6390 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6391 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6392 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6393 COND is the first argument to CODE; otherwise (as in the example
6394 given here), it is the second argument. TYPE is the type of the
6395 original expression. Return NULL_TREE if no simplification is
6396 possible. */
6398 static tree
6402 {
6409 /* This transformation is only worthwhile if we don't have to wrap
6410 arg in a SAVE_EXPR, and the operation can be simplified on at least
6411 one of the branches once its pushed inside the COND_EXPR. */
6416 {
6420 /* If this operand throws an expression, then it does not make
6421 sense to try to perform a logical or arithmetic operation
6422 involving it. */
6427 }
6428 else
6429 {
6434 }
6438 {
6442 else
6444 }
6446 {
6450 else
6452 }
6456 }
6458 \f
6459 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6461 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6462 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6463 ADDEND is the same as X.
6465 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6466 and finite. The problematic cases are when X is zero, and its mode
6467 has signed zeros. In the case of rounding towards -infinity,
6468 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6469 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6471 bool
6473 {
6477 /* Don't allow the fold with -fsignaling-nans. */
6481 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6485 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6490 /* The mode has signed zeros, and we have to honor their sign.
6491 In this situation, there is only one case we can return true for.
6492 X - 0 is the same as X unless rounding towards -infinity is
6493 supported. */
6495 }
6497 /* Subroutine of fold() that checks comparisons of built-in math
6498 functions against real constants.
6500 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6501 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6502 is the type of the result and ARG0 and ARG1 are the operands of the
6503 comparison. ARG1 must be a TREE_REAL_CST.
6505 The function returns the constant folded tree if a simplification
6506 can be made, and NULL_TREE otherwise. */
6508 static tree
6511 {
6512 REAL_VALUE_TYPE c;
6515 {
6521 {
6522 /* sqrt(x) < y is always false, if y is negative. */
6526 /* sqrt(x) > y is always true, if y is negative and we
6527 don't care about NaNs, i.e. negative values of x. */
6531 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6534 }
6536 {
6537 REAL_VALUE_TYPE c2;
6543 {
6544 /* sqrt(x) > y is x == +Inf, when y is very large. */
6549 /* sqrt(x) > y is always false, when y is very large
6550 and we don't care about infinities. */
6552 }
6554 /* sqrt(x) > c is the same as x > c*c. */
6557 }
6559 {
6560 REAL_VALUE_TYPE c2;
6566 {
6567 /* sqrt(x) < y is always true, when y is a very large
6568 value and we don't care about NaNs or Infinities. */
6572 /* sqrt(x) < y is x != +Inf when y is very large and we
6573 don't care about NaNs. */
6578 /* sqrt(x) < y is x >= 0 when y is very large and we
6579 don't care about Infinities. */
6584 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6593 dconst0)),
6596 c2)));
6597 }
6599 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6604 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6607 {
6612 dconst0)),
6615 c2)));
6616 }
6617 }
6618 }
6621 }
6623 /* Subroutine of fold() that optimizes comparisons against Infinities,
6624 either +Inf or -Inf.
6626 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6627 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6628 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6630 The function returns the constant folded tree if a simplification
6631 can be made, and NULL_TREE otherwise. */
6633 static tree
6635 {
6637 REAL_VALUE_TYPE max;
6638 tree temp;
6643 /* For negative infinity swap the sense of the comparison. */
6649 {
6651 /* x > +Inf is always false, if with ignore sNANs. */
6657 /* x <= +Inf is always true, if we don't case about NaNs. */
6661 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6664 {
6667 }
6672 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6678 /* x < +Inf is always equal to x <= DBL_MAX. */
6684 /* x != +Inf is always equal to !(x > DBL_MAX). */
6696 }
6699 }
6701 /* Subroutine of fold() that optimizes comparisons of a division by
6702 a nonzero integer constant against an integer constant, i.e.
6703 X/C1 op C2.
6705 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6706 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6707 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6709 The function returns the constant folded tree if a simplification
6710 can be made, and NULL_TREE otherwise. */
6712 static tree
6714 {
6719 HOST_WIDE_INT hpart;
6724 /* We have to do this the hard way to detect unsigned overflow.
6725 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6736 {
6741 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6749 }
6751 {
6755 {
6774 }
6775 }
6776 else
6777 {
6778 /* A negative divisor reverses the relational operators. */
6784 {
6803 }
6804 }
6807 {
6828 {
6831 }
6836 {
6839 }
6844 {
6847 }
6852 {
6855 }
6860 }
6863 }
6866 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6867 equality/inequality test, then return a simplified form of the test
6868 using a sign testing. Otherwise return NULL. TYPE is the desired
6869 result type. */
6871 static tree
6873 tree result_type)
6874 {
6875 /* If this is testing a single bit, we can optimize the test. */
6879 {
6880 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6881 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6885 /* This is only a win if casting to a signed type is cheap,
6886 i.e. when arg00's type is not a partial mode. */
6889 {
6894 }
6895 }
6898 }
6900 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6901 equality/inequality test, then return a simplified form of
6902 the test using shifts and logical operations. Otherwise return
6903 NULL. TYPE is the desired result type. */
6905 tree
6907 tree result_type)
6908 {
6909 /* If this is testing a single bit, we can optimize the test. */
6913 {
6922 /* First, see if we can fold the single bit test into a sign-bit
6923 test. */
6925 result_type);
6929 /* Otherwise we have (A & C) != 0 where C is a single bit,
6930 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6931 Similarly for (A & C) == 0. */
6933 /* If INNER is a right shift of a constant and it plus BITNUM does
6934 not overflow, adjust BITNUM and INNER. */
6941 {
6944 }
6946 /* If we are going to be able to omit the AND below, we must do our
6947 operations as unsigned. If we must use the AND, we have a choice.
6948 Normally unsigned is faster, but for some machines signed is. */
6949 #ifdef LOAD_EXTEND_OP
6952 #else
6954 #endif
6970 /* Put the AND last so it can combine with more things. */
6973 /* Make sure to return the proper type. */
6977 }
6979 }
6981 /* Check whether we are allowed to reorder operands arg0 and arg1,
6982 such that the evaluation of arg1 occurs before arg0. */
6984 static bool
6986 {
6993 }
6995 /* Test whether it is preferable two swap two operands, ARG0 and
6996 ARG1, for example because ARG0 is an integer constant and ARG1
6997 isn't. If REORDER is true, only recommend swapping if we can
6998 evaluate the operands in reverse order. */
7000 bool
7002 {
7038 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7039 for commutative and comparison operators. Ensuring a canonical
7040 form allows the optimizers to find additional redundancies without
7041 having to explicitly check for both orderings. */
7047 /* Put SSA_NAMEs last. */
7053 /* Put variables last. */
7060 }
7062 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7063 ARG0 is extended to a wider type. */
7065 static tree
7067 {
7069 tree arg1_unw;
7078 #ifdef HAVE_canonicalize_funcptr_for_compare
7079 /* Disable this optimization if we're casting a function pointer
7080 type on targets that require function pointer canonicalization. */
7085 #endif
7092 /* If possible, express the comparison in the shorter mode. */
7112 /* If we are comparing with the integer that does not fit into the range
7113 of the shorter type, the result is known. */
7124 {
7151 }
7154 }
7156 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7157 ARG0 just the signedness is changed. */
7159 static tree
7162 {
7163 tree arg0_inner;
7173 #ifdef HAVE_canonicalize_funcptr_for_compare
7174 /* Disable this optimization if we're casting a function pointer
7175 type on targets that require function pointer canonicalization. */
7180 #endif
7185 /* If the conversion is from an integral subtype to its basetype
7186 leave it alone. */
7205 else
7209 }
7211 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7212 step of the array. Reconstructs s and delta in the case of s * delta
7213 being an integer constant (and thus already folded).
7214 ADDR is the address. MULT is the multiplicative expression.
7215 If the function succeeds, the new address expression is returned. Otherwise
7216 NULL_TREE is returned. */
7218 static tree
7220 {
7224 tree itype;
7227 /* Strip the nops that might be added when converting op1 to sizetype. */
7230 /* Canonicalize op1 into a possibly non-constant delta
7231 and an INTEGER_CST s. */
7233 {
7240 {
7243 }
7245 {
7248 }
7249 else
7251 }
7253 {
7256 }
7257 else
7258 {
7259 /* Simulate we are delta * 1. */
7262 }
7265 {
7267 {
7268 /* Remember if this was a multi-dimensional array. */
7281 {
7284 }
7285 else
7286 {
7287 /* Try if delta is a multiple of step. */
7292 }
7294 /* Only fold here if we can verify we do not overflow one
7295 dimension of a multi-dimensional array. */
7297 {
7298 tree tmp;
7314 }
7317 }
7318 else
7323 }
7325 /* We found the suitable array reference. So copy everything up to it,
7326 and replace the index. */
7333 {
7337 }
7345 }
7348 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7349 means A >= Y && A != MAX, but in this case we know that
7350 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7352 static tree
7354 {
7361 else
7370 {
7373 }
7375 {
7378 }
7379 else
7386 {
7387 /* Convert the pointer types into integer before taking the difference. */
7391 }
7392 else
7399 }
7401 /* Fold a sum or difference of at least one multiplication.
7402 Returns the folded tree or NULL if no simplification could be made. */
7404 static tree
7406 {
7410 /* (A * C) +- (B * C) -> (A+-B) * C.
7411 (A * C) +- A -> A * (C+-1).
7412 We are most concerned about the case where C is a constant,
7413 but other combinations show up during loop reduction. Since
7414 it is not difficult, try all four possibilities. */
7417 {
7420 }
7422 {
7425 }
7426 else
7427 {
7428 /* We cannot generate constant 1 for fract. */
7433 }
7435 {
7438 }
7440 {
7442 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7443 the purpose of this canonicalization. */
7447 {
7450 }
7451 else
7453 }
7454 else
7455 {
7456 /* We cannot generate constant 1 for fract. */
7461 }
7473 /* No identical multiplicands; see if we can find a common
7474 power-of-two factor in non-power-of-two multiplies. This
7475 can help in multi-dimensional array access. */
7478 {
7481 tree maybe_same;
7485 /* Move min of absolute values to int11. */
7488 {
7493 }
7494 else
7498 {
7506 }
7507 }
7517 }
7519 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7520 specified by EXPR into the buffer PTR of length LEN bytes.
7521 Return the number of bytes placed in the buffer, or zero
7522 upon failure. */
7524 static int
7526 {
7537 {
7541 else
7546 {
7553 else
7555 }
7556 else
7559 }
7561 }
7564 /* Subroutine of native_encode_expr. Encode the REAL_CST
7565 specified by EXPR into the buffer PTR of length LEN bytes.
7566 Return the number of bytes placed in the buffer, or zero
7567 upon failure. */
7569 static int
7571 {
7577 /* There are always 32 bits in each long, no matter the size of
7578 the hosts long. We handle floating point representations with
7579 up to 192 bits. */
7590 {
7595 {
7602 else
7604 }
7605 else
7608 }
7610 }
7612 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7613 specified by EXPR into the buffer PTR of length LEN bytes.
7614 Return the number of bytes placed in the buffer, or zero
7615 upon failure. */
7617 static int
7619 {
7621 tree part;
7632 }
7635 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7636 specified by EXPR into the buffer PTR of length LEN bytes.
7637 Return the number of bytes placed in the buffer, or zero
7638 upon failure. */
7640 static int
7642 {
7652 {
7654 {
7657 }
7658 else
7662 {
7665 }
7666 else
7667 {
7671 }
7673 }
7675 }
7678 /* Subroutine of native_encode_expr. Encode the STRING_CST
7679 specified by EXPR into the buffer PTR of length LEN bytes.
7680 Return the number of bytes placed in the buffer, or zero
7681 upon failure. */
7683 static int
7685 {
7687 HOST_WIDE_INT total_bytes;
7698 {
7702 }
7703 else
7706 }
7709 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7710 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7711 buffer PTR of length LEN bytes. Return the number of bytes
7712 placed in the buffer, or zero upon failure. */
7714 int
7716 {
7718 {
7736 }
7737 }
7740 /* Subroutine of native_interpret_expr. Interpret the contents of
7741 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7742 If the buffer cannot be interpreted, return NULL_TREE. */
7744 static tree
7746 {
7760 {
7763 {
7770 else
7772 }
7773 else
7779 else
7782 }
7785 }
7788 /* Subroutine of native_interpret_expr. Interpret the contents of
7789 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7790 If the buffer cannot be interpreted, return NULL_TREE. */
7792 static tree
7794 {
7799 /* There are always 32 bits in each long, no matter the size of
7800 the hosts long. We handle floating point representations with
7801 up to 192 bits. */
7802 REAL_VALUE_TYPE r;
7813 {
7816 {
7823 else
7825 }
7826 else
7831 }
7835 }
7838 /* Subroutine of native_interpret_expr. Interpret the contents of
7839 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7840 If the buffer cannot be interpreted, return NULL_TREE. */
7842 static tree
7844 {
7859 }
7862 /* Subroutine of native_interpret_expr. Interpret the contents of
7863 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7864 If the buffer cannot be interpreted, return NULL_TREE. */
7866 static tree
7868 {
7880 {
7885 }
7887 }
7890 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7891 the buffer PTR of length LEN as a constant of type TYPE. For
7892 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7893 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7894 return NULL_TREE. */
7896 tree
7898 {
7900 {
7917 }
7918 }
7921 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7922 TYPE at compile-time. If we're unable to perform the conversion
7923 return NULL_TREE. */
7925 static tree
7927 {
7928 /* We support up to 512-bit values (for V8DFmode). */
7932 /* Check that the host and target are sane. */
7941 }
7943 /* Build an expression for the address of T. Folds away INDIRECT_REF
7944 to avoid confusing the gimplify process. When IN_FOLD is true
7945 avoid modifications of T. */
7947 static tree
7949 {
7950 /* The size of the object is not relevant when talking about its address. */
7954 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7957 {
7962 }
7964 {
7974 }
7975 else
7979 }
7981 /* Build an expression for the address of T with type PTRTYPE. This
7982 function modifies the input parameter 'T' by sometimes setting the
7983 TREE_ADDRESSABLE flag. */
7985 tree
7987 {
7989 }
7991 /* Build an expression for the address of T. This function modifies
7992 the input parameter 'T' by sometimes setting the TREE_ADDRESSABLE
7993 flag. When called from fold functions, use fold_addr_expr instead. */
7995 tree
7997 {
8001 }
8003 /* Same as build_fold_addr_expr, builds an expression for the address
8004 of T, but avoids touching the input node 't'. Fold functions
8005 should use this version. */
8007 static tree
8009 {
8013 }
8015 /* Fold a unary expression of code CODE and type TYPE with operand
8016 OP0. Return the folded expression if folding is successful.
8017 Otherwise, return NULL_TREE. */
8019 tree
8021 {
8022 tree tem;
8023 tree arg0;
8031 {
8034 {
8035 /* Don't use STRIP_NOPS, because signedness of argument type
8036 matters. */
8038 }
8039 else
8040 {
8041 /* Strip any conversions that don't change the mode. This
8042 is safe for every expression, except for a comparison
8043 expression because its signedness is derived from its
8044 operands.
8046 Note that this is done as an internal manipulation within
8047 the constant folder, in order to find the simplest
8048 representation of the arguments so that their form can be
8049 studied. In any cases, the appropriate type conversions
8050 should be put back in the tree that will get out of the
8051 constant folder. */
8053 }
8054 }
8057 {
8064 {
8076 /* If this was a conversion, and all we did was to move into
8077 inside the COND_EXPR, bring it back out. But leave it if
8078 it is a conversion from integer to integer and the
8079 result precision is no wider than a word since such a
8080 conversion is cheap and may be optimized away by combine,
8081 while it couldn't if it were outside the COND_EXPR. Then return
8082 so we don't get into an infinite recursion loop taking the
8083 conversion out and then back in. */
8095 && (INTEGRAL_TYPE_P
8107 }
8109 {
8111 {
8115 }
8119 integer_one_node),
8121 integer_zero_node));
8122 }
8123 }
8126 {
8128 /* Re-association barriers around constants and other re-association
8129 barriers can be removed. */
8135 CASE_CONVERT:
8141 /* If we have (type) (a CMP b) and type is an integral type, return
8142 new expression involving the new type. */
8147 /* Handle cases of two conversions in a row. */
8149 {
8171 /* In addition to the cases of two conversions in a row
8172 handled below, if we are converting something to its own
8173 type via an object of identical or wider precision, neither
8174 conversion is needed. */
8181 /* Likewise, if the intermediate and final types are either both
8182 float or both integer, we don't need the middle conversion if
8183 it is wider than the final type and doesn't change the signedness
8184 (for integers). Avoid this if the final type is a pointer
8185 since then we sometimes need the inner conversion. Likewise if
8186 the outer has a precision not equal to the size of its mode. */
8195 && ! final_ptr
8199 /* If we have a sign-extension of a zero-extended value, we can
8200 replace that by a single zero-extension. */
8206 /* Two conversions in a row are not needed unless:
8207 - some conversion is floating-point (overstrict for now), or
8208 - some conversion is a vector (overstrict for now), or
8209 - the intermediate type is narrower than both initial and
8210 final, or
8211 - the intermediate type and innermost type differ in signedness,
8212 and the outermost type is wider than the intermediate, or
8213 - the initial type is a pointer type and the precisions of the
8214 intermediate and final types differ, or
8215 - the final type is a pointer type and the precisions of the
8216 initial and intermediate types differ. */
8230 }
8232 /* Handle (T *)&A.B.C for A being of type T and B and C
8233 living at offset zero. This occurs frequently in
8234 C++ upcasting and then accessing the base. */
8238 {
8240 tree offset;
8246 /* If the reference was to a (constant) zero offset, we can use
8247 the address of the base if it has the same base type
8248 as the result type. */
8253 }
8257 /* Detect assigning a bitfield. */
8259 && DECL_BIT_FIELD
8261 {
8262 /* Don't leave an assignment inside a conversion
8263 unless assigning a bitfield. */
8265 /* First do the assignment, then return converted constant. */
8270 }
8272 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8273 constants (if x has signed type, the sign bit cannot be set
8274 in c). This folds extension into the BIT_AND_EXPR.
8275 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8276 very likely don't have maximal range for their precision and this
8277 transformation effectively doesn't preserve non-maximal ranges. */
8281 /* Not if the conversion is to the sub-type. */
8283 {
8293 <= HOST_BITS_PER_WIDE_INT
8295 {
8302 #ifdef LOAD_EXTEND_OP
8304 && !flag_syntax_only
8307 {
8311 }
8312 #endif
8313 }
8315 {
8321 }
8322 }
8324 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8325 when one of the new casts will fold away. Conservatively we assume
8326 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8332 {
8338 }
8340 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8341 of the same precision, and X is an integer type not narrower than
8342 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8348 {
8353 }
8355 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8356 type of X and Y (integer types only). */
8361 {
8362 /* Be careful not to introduce new overflows. */
8363 tree mult_type;
8366 else
8370 {
8377 }
8378 }
8393 /* For integral conversions with the same precision or pointer
8394 conversions use a NOP_EXPR instead. */
8400 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8401 a sub-type to its base type as generated by the Ada FE. */
8406 /* Strip inner integral conversions that do not change the precision. */
8430 /* Convert fabs((double)float) into (double)fabsf(float). */
8433 {
8438 targ0));
8439 }
8440 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8446 /* Strip sign ops from argument. */
8448 {
8452 }
8459 {
8464 }
8466 {
8471 }
8481 /* Convert ~ (-A) to A - 1. */
8486 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8494 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8507 /* Perform BIT_NOT_EXPR on each element individually. */
8509 {
8514 {
8516 {
8522 }
8523 else
8526 }
8529 }
8534 /* The argument to invert_truthvalue must have Boolean type. */
8538 /* Note that the operand of this must be an int
8539 and its values must be 0 or 1.
8540 ("true" is a fixed value perhaps depending on the language,
8541 but we don't handle values other than 1 correctly yet.) */
8556 {
8564 }
8566 {
8570 }
8572 {
8576 {
8585 }
8586 }
8598 {
8606 }
8608 {
8612 }
8614 {
8618 {
8627 }
8628 }
8634 }
8637 /* If the operation was a conversion do _not_ mark a resulting constant
8638 with TREE_OVERFLOW if the original constant was not. These conversions
8639 have implementation defined behavior and retaining the TREE_OVERFLOW
8640 flag here would confuse later passes such as VRP. */
8641 tree
8643 {
8652 }
8654 /* Fold a binary expression of code CODE and type TYPE with operands
8655 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8656 Return the folded expression if folding is successful. Otherwise,
8657 return NULL_TREE. */
8659 static tree
8661 {
8668 else
8671 /* MIN (MAX (a, b), b) == b. */
8676 /* MIN (MAX (b, a), b) == b. */
8682 /* MIN (a, MAX (a, b)) == a. */
8688 /* MIN (a, MAX (b, a)) == a. */
8695 }
8697 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8698 by changing CODE to reduce the magnitude of constants involved in
8699 ARG0 of the comparison.
8700 Returns a canonicalized comparison tree if a simplification was
8701 possible, otherwise returns NULL_TREE.
8702 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8703 valid if signed overflow is undefined. */
8705 static tree
8709 {
8715 /* Match A +- CST code arg1 and CST code arg1. We can change the
8716 first form only if overflow is undefined. */
8718 /* In principle pointers also have undefined overflow behavior,
8719 but that causes problems elsewhere. */
8727 /* Identify the constant in arg0 and its sign. */
8730 else
8734 /* Overflowed constants and zero will cause problems. */
8739 /* See if we can reduce the magnitude of the constant in
8740 arg0 by changing the comparison code. */
8742 {
8743 /* CST <= arg1 -> CST-1 < arg1. */
8746 /* -CST < arg1 -> -CST-1 <= arg1. */
8749 /* CST > arg1 -> CST-1 >= arg1. */
8752 /* -CST >= arg1 -> -CST-1 > arg1. */
8755 else
8757 /* arg1 code' CST' might be more canonical. */
8759 }
8760 else
8761 {
8762 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8766 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8770 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8774 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8778 else
8781 }
8783 /* Now build the constant reduced in magnitude. But not if that
8784 would produce one outside of its types range. */
8792 /* We cannot swap the comparison here as that would cause us to
8793 endlessly recurse. */
8801 /* If swapping might yield to a more canonical form, do so. */
8804 else
8806 }
8808 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8809 overflow further. Try to decrease the magnitude of constants involved
8810 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8811 and put sole constants at the second argument position.
8812 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8814 static tree
8817 {
8818 tree t;
8823 /* Try canonicalization by simplifying arg0. */
8828 {
8832 }
8834 /* Try canonicalization by simplifying arg1 using the swapped
8835 comparison. */
8843 }
8845 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8846 space. This is used to avoid issuing overflow warnings for
8847 expressions like &p->x which can not wrap. */
8849 static bool
8851 {
8862 {
8865 }
8868 else
8869 {
8872 }
8887 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8888 array. */
8890 {
8891 HOST_WIDE_INT base_size;
8896 }
8899 }
8901 /* Subroutine of fold_binary. This routine performs all of the
8902 transformations that are common to the equality/inequality
8903 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8904 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8905 fold_binary should call fold_binary. Fold a comparison with
8906 tree code CODE and type TYPE with operands OP0 and OP1. Return
8907 the folded comparison or NULL_TREE. */
8909 static tree
8911 {
8924 /* If one arg is a real or integer constant, put it last. */
8928 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8935 {
8939 tree lhs;
8946 /* If the constant operation overflowed this can be
8947 simplified as a comparison against INT_MAX/INT_MIN. */
8950 {
8954 /* Get the sign of the constant on the lhs if the
8955 operation were VARIABLE + CONST1. */
8959 /* The sign of the constant determines if we overflowed
8960 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8961 Canonicalize to the INT_MIN overflow by swapping the comparison
8962 if necessary. */
8966 /* We now can look at the canonicalized case
8967 VARIABLE + 1 CODE2 INT_MIN
8968 and decide on the result. */
8977 }
8982 {
8984 "when changing X +- C1 cmp C2 to "
8986 WARN_STRICT_OVERFLOW_COMPARISON);
8988 }
8989 }
8991 /* For comparisons of pointers we can decompose it to a compile time
8992 comparison of the base objects and the offsets into the object.
8993 This requires at least one operand being an ADDR_EXPR or a
8994 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9000 {
9007 /* Get base and offset for the access. Strip ADDR_EXPR for
9008 get_inner_reference, but put it back by stripping INDIRECT_REF
9009 off the base object if possible. indirect_baseN will be true
9010 if baseN is not an address but refers to the object itself. */
9013 {
9019 else
9021 }
9023 {
9026 }
9030 {
9036 else
9038 }
9040 {
9043 }
9045 /* If we have equivalent bases we might be able to simplify. */
9048 {
9049 /* We can fold this expression to a constant if the non-constant
9050 offset parts are equal. */
9058 {
9065 "occur when comparing P +- C1 with "
9067 WARN_STRICT_OVERFLOW_CONDITIONAL);
9070 {
9084 }
9085 }
9086 /* We can simplify the comparison to a comparison of the variable
9087 offset parts if the constant offset parts are equal.
9088 Be careful to use signed size type here because otherwise we
9089 mess with array offsets in the wrong way. This is possible
9090 because pointer arithmetic is restricted to retain within an
9091 object and overflow on pointer differences is undefined as of
9092 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9096 {
9097 tree signed_size_type_node;
9100 /* By converting to signed size type we cover middle-end pointer
9101 arithmetic which operates on unsigned pointer types of size
9102 type size and ARRAY_REF offsets which are properly sign or
9103 zero extended from their type in case it is narrower than
9104 size type. */
9107 else
9111 else
9119 "occur when comparing P +- C1 with "
9121 WARN_STRICT_OVERFLOW_COMPARISON);
9124 }
9125 }
9126 /* For non-equal bases we can simplify if they are addresses
9127 of local binding decls or constants. */
9129 /* We know that !operand_equal_p (base0, base1, 0)
9130 because the if condition was false. But make
9131 sure two decls are not the same. */
9145 {
9150 }
9151 /* For equal offsets we can simplify to a comparison of the
9152 base addresses. */
9154 && (indirect_base0
9156 && (indirect_base1
9161 {
9167 }
9168 }
9170 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9171 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9172 the resulting offset is smaller in absolute value than the
9173 original one. */
9181 {
9186 tree cst;
9188 "occur when combining constants around "
9191 /* Put the constant on the side where it doesn't overflow and is
9192 of lower absolute value than before. */
9198 {
9201 variable1,
9204 }
9211 {
9216 variable2);
9217 }
9218 }
9220 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9221 signed arithmetic case. That form is created by the compiler
9222 often enough for folding it to be of value. One example is in
9223 computing loop trip counts after Operator Strength Reduction. */
9229 {
9238 "eliminating multiplication in comparison "
9240 WARN_STRICT_OVERFLOW_COMPARISON);
9242 /* If const1 is negative we swap the sense of the comparison. */
9247 }
9254 {
9262 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9267 /* (-a) CMP (-b) -> b CMP a */
9274 {
9275 REAL_VALUE_TYPE cst;
9278 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9285 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9286 /* a CMP (-0) -> a CMP 0 */
9291 /* x != NaN is always true, other ops are always false. */
9294 {
9297 }
9299 /* Fold comparisons against infinity. */
9301 {
9305 }
9306 }
9308 /* If this is a comparison of a real constant with a PLUS_EXPR
9309 or a MINUS_EXPR of a real constant, we can convert it into a
9310 comparison with a revised real constant as long as no overflow
9311 occurs when unsafe_math_optimizations are enabled. */
9323 /* Likewise, we can simplify a comparison of a real constant with
9324 a MINUS_EXPR whose first operand is also a real constant, i.e.
9325 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9326 floating-point types only if -fassociative-math is set. */
9337 /* Fold comparisons against built-in math functions. */
9339 && flag_unsafe_math_optimizations
9341 {
9345 {
9349 }
9350 }
9351 }
9355 {
9356 /* If we are widening one operand of an integer comparison,
9357 see if the other operand is similarly being widened. Perhaps we
9358 can do the comparison in the narrower type. */
9363 /* Or if we are changing signedness. */
9367 }
9369 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9370 constant, we can simplify it. */
9375 {
9379 }
9381 /* Simplify comparison of something with itself. (For IEEE
9382 floating-point, we can only do some of these simplifications.) */
9384 {
9386 {
9401 /* For NE, we can only do this simplification if integer
9402 or we don't honor IEEE floating point NaNs. */
9406 /* ... fall through ... */
9412 }
9413 }
9415 /* If we are comparing an expression that just has comparisons
9416 of two integer values, arithmetic expressions of those comparisons,
9417 and constants, we can simplify it. There are only three cases
9418 to check: the two values can either be equal, the first can be
9419 greater, or the second can be greater. Fold the expression for
9420 those three values. Since each value must be 0 or 1, we have
9421 eight possibilities, each of which corresponds to the constant 0
9422 or 1 or one of the six possible comparisons.
9424 This handles common cases like (a > b) == 0 but also handles
9425 expressions like ((x > y) - (y > x)) > 0, which supposedly
9426 occur in macroized code. */
9429 {
9434 /* Don't handle degenerate cases here; they should already
9435 have been handled anyway. */
9444 {
9448 /* We can't just pass T to eval_subst in case cval1 or cval2
9449 was the same as ARG1. */
9451 tree high_result
9455 arg1);
9456 tree equal_result
9460 arg1);
9461 tree low_result
9465 arg1);
9467 /* All three of these results should be 0 or 1. Confirm they are.
9468 Then use those values to select the proper code to use. */
9473 {
9474 /* Make a 3-bit mask with the high-order bit being the
9475 value for `>', the next for '=', and the low for '<'. */
9479 {
9481 /* Always false. */
9502 /* Always true. */
9504 }
9509 }
9510 }
9511 }
9513 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9514 into a single range test. */
9522 {
9526 }
9528 /* Fold ~X op ~Y as Y op X. */
9531 {
9536 }
9538 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9541 {
9547 }
9550 }
9553 /* Subroutine of fold_binary. Optimize complex multiplications of the
9554 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9555 argument EXPR represents the expression "z" of type TYPE. */
9557 static tree
9559 {
9564 {
9567 }
9569 {
9572 }
9573 else
9574 {
9578 }
9587 }
9590 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9591 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9592 guarantees that P and N have the same least significant log2(M) bits.
9593 N is not otherwise constrained. In particular, N is not normalized to
9594 0 <= N < M as is common. In general, the precise value of P is unknown.
9595 M is chosen as large as possible such that constant N can be determined.
9597 Returns M and sets *RESIDUE to N. */
9599 static unsigned HOST_WIDE_INT
9601 {
9608 {
9611 {
9613 tree offset;
9621 {
9624 else
9625 /* We don't handle more complicated offset expressions. */
9627 }
9628 }
9632 }
9634 {
9647 {
9650 }
9652 {
9655 {
9658 /* Compute the greatest power-of-2 divisor of op1. */
9662 /* If align is non-zero and less than *modulus, replace
9663 *modulus with align., If align is 0, then either op1 is 0
9664 or the greatest power-of-2 divisor of op1 doesn't fit in an
9665 unsigned HOST_WIDE_INT. In either case, no additional
9666 constraint is imposed. */
9671 }
9672 }
9673 }
9675 /* If we get here, we were unable to determine anything useful about the
9676 expression. */
9678 }
9681 /* Fold a binary expression of code CODE and type TYPE with operands
9682 OP0 and OP1. Return the folded expression if folding is
9683 successful. Otherwise, return NULL_TREE. */
9685 tree
9687 {
9701 /* Strip any conversions that don't change the mode. This is
9702 safe for every expression, except for a comparison expression
9703 because its signedness is derived from its operands. So, in
9704 the latter case, only strip conversions that don't change the
9705 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9706 preserved.
9708 Note that this is done as an internal manipulation within the
9709 constant folder, in order to find the simplest representation
9710 of the arguments so that their form can be studied. In any
9711 cases, the appropriate type conversions should be put back in
9712 the tree that will get out of the constant folder. */
9715 {
9718 }
9719 else
9720 {
9723 }
9725 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9726 constant but we can't do arithmetic on them. */
9733 {
9735 {
9736 /* Make sure type and arg0 have the same saturating flag. */
9740 }
9743 else
9747 {
9751 }
9752 }
9754 /* If this is a commutative operation, and ARG0 is a constant, move it
9755 to ARG1 to reduce the number of tests below. */
9760 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9762 First check for cases where an arithmetic operation is applied to a
9763 compound, conditional, or comparison operation. Push the arithmetic
9764 operation inside the compound or conditional to see if any folding
9765 can then be done. Convert comparison to conditional for this purpose.
9766 The also optimizes non-constant cases that used to be done in
9767 expand_expr.
9769 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9770 one of the operands is a comparison and the other is a comparison, a
9771 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9772 code below would make the expression more complex. Change it to a
9773 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9774 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9786 {
9790 boolean_type_node,
9798 }
9802 {
9808 op1));
9817 {
9823 }
9826 {
9832 }
9833 }
9836 {
9839 /* 0 +p index -> (type)index */
9843 /* PTR +p 0 -> PTR */
9847 /* PTR_CST +p CST -> CST1 */
9851 /* ??? Auditing required. */
9855 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9862 /* index +p PTR -> PTR +p index */
9869 /* (PTR +p B) +p A -> PTR +p (B + A) */
9871 {
9872 tree inner;
9880 }
9882 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9883 of the array. Loop optimizer sometimes produce this type of
9884 expressions. */
9886 {
9890 }
9897 {
9900 }
9902 /* ??? Auditing required. */
9906 /* A + (-B) -> A - B */
9911 /* (-A) + B -> B - A */
9919 {
9920 /* Convert ~A + 1 to -A. */
9926 /* ~X + X is -1. */
9929 {
9934 {
9937 }
9938 }
9940 /* X + ~X is -1. */
9943 {
9948 {
9951 }
9952 }
9954 /* X + (X / CST) * -CST is X % CST. */
9959 {
9967 }
9968 }
9970 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9971 same or one. Make sure type is not saturating.
9972 fold_plusminus_mult_expr will re-associate. */
9977 {
9981 }
9984 {
9985 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9986 with a constant, and the two constants have no bits in common,
9987 we should treat this as a BIT_IOR_EXPR since this may produce more
9988 simplifications. */
9996 {
9999 }
10001 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10002 (plus (plus (mult) (mult)) (foo)) so that we can
10003 take advantage of the factoring cases below. */
10010 {
10016 else
10038 parg1)));
10039 }
10040 }
10041 else
10042 {
10043 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10047 /* Likewise if the operands are reversed. */
10051 /* Convert X + -C into X - C. */
10054 {
10060 }
10062 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10063 to __complex__ ( x, y ). This is not the same for SNaNs or
10064 if signed zeros are involved. */
10068 {
10075 {
10079 {
10085 }
10087 {
10093 }
10094 }
10095 }
10103 /* Convert x+x into x*2.0. */
10109 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10110 We associate floats only if the user has specified
10111 -fassociative-math. */
10115 {
10120 {
10121 tree tree0;
10124 }
10125 }
10126 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10127 We associate floats only if the user has specified
10128 -fassociative-math. */
10132 {
10137 {
10138 tree tree0;
10141 }
10142 }
10143 }
10145 bit_rotate:
10146 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10147 is a rotate of A by C1 bits. */
10148 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10149 is a rotate of A by B bits. */
10150 {
10152 tree rtype;
10161 /* Only create rotates in complete modes. Other cases are not
10162 expanded properly. */
10164 {
10183 {
10191 TYPE_PRECISION
10196 ? LROTATE_EXPR
10199 }
10201 {
10209 TYPE_PRECISION
10214 ? LROTATE_EXPR
10217 }
10218 }
10219 }
10221 associate:
10222 /* In most languages, can't associate operations on floats through
10223 parentheses. Rather than remember where the parentheses were, we
10224 don't associate floats at all, unless the user has specified
10225 -fassociative-math.
10226 And, we need to make sure type is not saturating. */
10230 {
10235 /* Split both trees into variables, constants, and literals. Then
10236 associate each group together, the constants with literals,
10237 then the result with variables. This increases the chances of
10238 literals being recombined later and of generating relocatable
10239 expressions for the sum of a constant and literal. */
10244 /* With undefined overflow we can only associate constants
10245 with one variable. */
10249 {
10257 /* The only case we can still associate with two variables
10258 is if they are the same, modulo negation. */
10261 }
10263 /* Only do something if we found more than two objects. Otherwise,
10264 nothing has changed and we risk infinite recursion. */
10270 {
10271 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10280 /* Preserve the MINUS_EXPR if the negative part of the literal is
10281 greater than the positive part. Otherwise, the multiplicative
10282 folding code (i.e extract_muldiv) may be fooled in case
10283 unsigned constants are subtracted, like in the following
10284 example: ((X*2 + 4) - 8U)/2. */
10286 {
10290 {
10294 }
10295 else
10296 {
10300 }
10301 }
10303 {
10308 else
10309 {
10315 }
10316 }
10321 }
10322 }
10329 {
10334 }
10336 /* ??? Auditing required. */
10340 /* Pointer simplifications for subtraction, simple reassociations. */
10342 {
10343 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10346 {
10354 }
10355 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10357 {
10363 }
10364 }
10365 /* A - (-B) -> A + B */
10369 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10378 /* Convert -A - 1 to ~A. */
10386 /* Convert -1 - A to ~A. */
10392 /* X - (X / CST) * CST is X % CST. */
10405 {
10406 /* Fold A - (A & B) into ~B & A. */
10409 {
10411 {
10416 }
10418 {
10423 }
10424 }
10426 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10427 any power of 2 minus 1. */
10432 {
10438 {
10442 }
10443 }
10444 }
10446 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10450 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10451 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10452 (-ARG1 + ARG0) reduces to -ARG1. */
10456 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10457 __complex__ ( x, -y ). This is not the same for SNaNs or if
10458 signed zeros are involved. */
10462 {
10469 {
10473 {
10475 arg1r ? arg1r
10480 }
10482 {
10486 arg1i ? arg1i
10489 }
10490 }
10491 }
10493 /* Fold &x - &x. This can happen from &x.foo - &x.
10494 This is unsafe for certain floats even in non-IEEE formats.
10495 In IEEE, it is unsafe because it does wrong for NaNs.
10496 Also note that operand_equal_p is always false if an operand
10497 is volatile. */
10503 /* A - B -> A + (-B) if B is easily negatable. */
10506 /* Avoid this transformation if B is a positive REAL_CST. */
10514 /* Try folding difference of addresses. */
10515 {
10516 HOST_WIDE_INT diff;
10522 }
10524 /* Fold &a[i] - &a[j] to i-j. */
10529 {
10534 {
10542 }
10543 }
10551 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10552 same or one. Make sure type is not saturating.
10553 fold_plusminus_mult_expr will re-associate. */
10558 {
10562 }
10569 {
10574 /* Transform x * -1 into -x. Make sure to do the negation
10575 on the original operand with conversions not stripped
10576 because we can only strip non-sign-changing conversions. */
10579 }
10581 /* ??? Auditing required. */
10585 /* (-A) * (-B) -> A * B */
10596 {
10597 /* Transform x * -C into -x * C if x is easily negatable. */
10606 /* (a * (1 << b)) is (a << b) */
10616 /* (A + A) * C -> A * 2 * C */
10631 {
10634 "occur when simplifying "
10636 WARN_STRICT_OVERFLOW_MISC);
10638 }
10640 /* Optimize z * conj(z) for integer complex numbers. */
10647 }
10648 else
10649 {
10650 /* Maybe fold x * 0 to 0. The expressions aren't the same
10651 when x is NaN, since x * 0 is also NaN. Nor are they the
10652 same in modes with signed zeros, since multiplying a
10653 negative value by 0 gives -0, not +0. */
10658 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10663 /* Transform x * -1.0 into -x. */
10668 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10669 the result for floating point types due to rounding so it is applied
10670 only if -fassociative-math was specify. */
10675 {
10681 }
10683 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10685 {
10688 {
10691 }
10692 }
10694 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10695 This is not the same for NaNs or if signed zeros are
10696 involved. */
10702 {
10714 }
10716 /* Optimize z * conj(z) for floating point complex numbers.
10717 Guarded by flag_unsafe_math_optimizations as non-finite
10718 imaginary components don't produce scalar results. */
10729 {
10733 /* Optimizations of root(...)*root(...). */
10735 {
10740 /* Optimize sqrt(x)*sqrt(x) as x. */
10746 /* Optimize root(x)*root(y) as root(x*y). */
10750 }
10752 /* Optimize expN(x)*expN(y) as expN(x+y). */
10754 {
10760 }
10762 /* Optimizations of pow(...)*pow(...). */
10766 {
10772 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10774 {
10778 }
10780 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10782 {
10786 }
10787 }
10789 /* Optimize tan(x)*cos(x) as sin(x). */
10798 {
10803 }
10805 /* Optimize x*pow(x,c) as pow(x,c+1). */
10809 {
10815 {
10817 REAL_VALUE_TYPE c;
10818 tree arg;
10824 }
10825 }
10827 /* Optimize pow(x,c)*x as pow(x,c+1). */
10831 {
10837 {
10839 REAL_VALUE_TYPE c;
10840 tree arg;
10846 }
10847 }
10849 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10852 {
10856 {
10859 }
10860 }
10861 }
10862 }
10866 bit_ior:
10874 /* ~X | X is -1. */
10877 {
10881 }
10883 /* X | ~X is -1. */
10886 {
10890 }
10892 /* Canonicalize (X & C1) | C2. */
10896 {
10904 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10909 {
10913 }
10914 else
10915 {
10919 }
10921 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10926 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10927 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10928 mode which allows further optimizations. */
10938 {
10939 unsigned HOST_WIDE_INT mask
10943 {
10947 }
10948 }
10955 arg1);
10956 }
10958 /* (X & Y) | Y is (X, Y). */
10962 /* (X & Y) | X is (Y, X). */
10967 /* X | (X & Y) is (Y, X). */
10972 /* X | (Y & X) is (Y, X). */
10982 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10984 This results in more efficient code for machines without a NAND
10985 instruction. Combine will canonicalize to the first form
10986 which will allow use of NAND instructions provided by the
10987 backend if they exist. */
10990 {
10997 }
10999 /* See if this can be simplified into a rotate first. If that
11000 is unsuccessful continue in the association code. */
11011 /* ~X ^ X is -1. */
11014 {
11018 }
11020 /* X ^ ~X is -1. */
11023 {
11027 }
11029 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11030 with a constant, and the two constants have no bits in common,
11031 we should treat this as a BIT_IOR_EXPR since this may produce more
11032 simplifications. */
11040 {
11043 }
11045 /* (X | Y) ^ X -> Y & ~ X*/
11048 {
11051 arg1);
11055 }
11057 /* (Y | X) ^ X -> Y & ~ X*/
11060 {
11063 arg1);
11067 }
11069 /* X ^ (X | Y) -> Y & ~ X*/
11072 {
11075 arg0);
11079 }
11081 /* X ^ (Y | X) -> Y & ~ X*/
11084 {
11087 arg0);
11091 }
11093 /* Convert ~X ^ ~Y to X ^ Y. */
11100 /* Convert ~X ^ C to X ^ ~C. */
11107 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11114 /* Fold (X & Y) ^ Y as ~X & Y. */
11117 {
11122 }
11123 /* Fold (X & Y) ^ X as ~Y & X. */
11127 {
11132 }
11133 /* Fold X ^ (X & Y) as X & ~Y. */
11136 {
11141 }
11142 /* Fold X ^ (Y & X) as ~Y & X. */
11146 {
11151 }
11153 /* See if this can be simplified into a rotate first. If that
11154 is unsuccessful continue in the association code. */
11165 /* ~X & X is always zero. */
11170 /* X & ~X is always zero. */
11175 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11179 {
11187 }
11189 /* (X | Y) & Y is (X, Y). */
11193 /* (X | Y) & X is (Y, X). */
11198 /* X & (X | Y) is (Y, X). */
11203 /* X & (Y | X) is (Y, X). */
11209 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11213 {
11219 }
11220 /* Fold ~X & 1 as (X & 1) == 0. */
11223 {
11229 }
11231 /* Fold (X ^ Y) & Y as ~X & Y. */
11234 {
11239 }
11240 /* Fold (X ^ Y) & X as ~Y & X. */
11244 {
11249 }
11250 /* Fold X & (X ^ Y) as X & ~Y. */
11253 {
11258 }
11259 /* Fold X & (Y ^ X) as ~Y & X. */
11263 {
11268 }
11273 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11276 {
11277 unsigned int prec
11284 }
11286 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11288 This results in more efficient code for machines without a NOR
11289 instruction. Combine will canonicalize to the first form
11290 which will allow use of NOR instructions provided by the
11291 backend if they exist. */
11294 {
11301 }
11303 /* If arg0 is derived from the address of an object or function, we may
11304 be able to fold this expression using the object or function's
11305 alignment. */
11307 {
11313 /* This works because modulus is a power of 2. If this weren't the
11314 case, we'd have to replace it by its greatest power-of-2
11315 divisor: modulus & -modulus. */
11318 }
11320 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11321 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11322 if the new mask might be further optimized. */
11331 {
11333 unsigned HOST_WIDE_INT mask
11343 {
11346 /* See if more bits can be proven as zero because of
11347 zero extension. */
11350 {
11355 {
11357 /* See if we can shorten the right shift. */
11360 }
11361 }
11365 /* For arithmetic shift if sign bit could be set, zerobits
11366 can contain actually sign bits, so no transformation is
11367 possible, unless MASK masks them all away. In that
11368 case the shift needs to be converted into logical shift. */
11371 {
11374 else
11376 }
11377 }
11379 /* ((X << 16) & 0xff00) is (X, 0). */
11385 {
11388 /* Only do the transformation if NEWMASK is some integer
11389 mode's mask. */
11396 {
11398 {
11404 }
11405 else
11409 newmask));
11410 }
11411 }
11412 }
11417 /* Don't touch a floating-point divide by zero unless the mode
11418 of the constant can represent infinity. */
11424 /* Optimize A / A to 1.0 if we don't care about
11425 NaNs or Infinities. Skip the transformation
11426 for non-real operands. */
11431 {
11435 }
11437 /* The complex version of the above A / A optimization. */
11440 {
11444 {
11446 /* omit_two_operands will call fold_convert for us. */
11448 }
11449 }
11451 /* (-A) / (-B) -> A / B */
11461 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11466 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11471 /* If ARG1 is a constant, we can convert this to a multiply by the
11472 reciprocal. This does not have the same rounding properties,
11473 so only do this if -freciprocal-math. We can actually
11474 always safely do it if ARG1 is a power of two, but it's hard to
11475 tell if it is or not in a portable manner. */
11477 {
11482 /* Find the reciprocal if optimizing and the result is exact. */
11484 {
11485 REAL_VALUE_TYPE r;
11488 {
11492 }
11493 }
11494 }
11495 /* Convert A/B/C to A/(B*C). */
11502 /* Convert A/(B/C) to (A/B)*C. */
11510 /* Convert C1/(X*C2) into (C1/C2)/X. */
11515 {
11521 }
11524 {
11528 /* Optimize sin(x)/cos(x) as tan(x). */
11534 {
11539 }
11541 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11547 {
11551 {
11555 }
11556 }
11558 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11559 NaNs or Infinities. */
11563 {
11570 {
11575 }
11576 }
11578 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11579 NaNs or Infinities. */
11583 {
11590 {
11594 {
11598 tmp);
11599 }
11600 }
11601 }
11603 /* Optimize pow(x,c)/x as pow(x,c-1). */
11607 {
11613 {
11615 REAL_VALUE_TYPE c;
11616 tree arg;
11622 }
11623 }
11625 /* Optimize a/root(b/c) into a*root(c/b). */
11627 {
11631 {
11640 }
11641 }
11643 /* Optimize x/expN(y) into x*expN(-y). */
11645 {
11650 }
11652 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11656 {
11663 }
11664 }
11669 /* Simplify A / (B << N) where A and B are positive and B is
11670 a power of 2, to A >> (N + log2(B)). */
11675 {
11678 {
11685 WARN_STRICT_OVERFLOW_MISC);
11691 }
11692 }
11694 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11695 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11701 /* Fall thru */
11710 /* X / -1 is -X. */
11717 /* Convert -A / -B to A / B when the type is signed and overflow is
11718 undefined. */
11722 {
11725 "when distributing negation across "
11727 WARN_STRICT_OVERFLOW_MISC);
11731 }
11735 {
11738 "when distributing negation across "
11740 WARN_STRICT_OVERFLOW_MISC);
11744 }
11746 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11747 operation, EXACT_DIV_EXPR.
11749 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11750 At one time others generated faster code, it's not clear if they do
11751 after the last round to changes to the DIV code in expmed.c. */
11760 {
11764 WARN_STRICT_OVERFLOW_MISC);
11766 }
11774 /* X % 1 is always zero, but be sure to preserve any side
11775 effects in X. */
11779 /* X % 0, return X % 0 unchanged so that we can get the
11780 proper warnings and errors. */
11784 /* 0 % X is always zero, but be sure to preserve any side
11785 effects in X. Place this after checking for X == 0. */
11789 /* X % -1 is zero. */
11796 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11797 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11802 {
11804 /* Also optimize A % (C << N) where C is a power of 2,
11805 to A & ((C << N) - 1). */
11810 {
11815 "occur when simplifying "
11817 WARN_STRICT_OVERFLOW_MISC);
11821 }
11822 }
11824 /* X % -C is the same as X % C. */
11831 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11836 /* X % -Y is the same as X % Y. */
11847 {
11851 WARN_STRICT_OVERFLOW_MISC);
11853 }
11864 /* Optimize -1 >> x for arithmetic right shifts. */
11868 /* ... fall through ... */
11871 shift:
11877 /* Since negative shift count is not well-defined,
11878 don't try to compute it in the compiler. */
11882 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11887 {
11891 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11892 being well defined. */
11894 {
11899 else
11901 }
11905 }
11907 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11908 into x & ((unsigned)-1 >> c) for unsigned types. */
11916 {
11919 tree lshift;
11920 tree arg00;
11923 {
11930 }
11931 }
11933 /* Rewrite an LROTATE_EXPR by a constant into an
11934 RROTATE_EXPR by a new constant. */
11936 {
11941 }
11943 /* If we have a rotate of a bit operation with the rotate count and
11944 the second operand of the bit operation both constant,
11945 permute the two operations. */
11957 /* Two consecutive rotates adding up to the precision of the
11958 type can be ignored. */
11969 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11970 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11971 if the latter can be further optimized. */
11976 {
11979 arg1);
11982 arg1);
11986 }
12014 /* Note that the operands of this must be ints
12015 and their values must be 0 or 1.
12016 ("true" is a fixed value perhaps depending on the language.) */
12017 /* If first arg is constant zero, return it. */
12021 /* If either arg is constant true, drop it. */
12025 /* Preserve sequence points. */
12028 /* If second arg is constant zero, result is zero, but first arg
12029 must be evaluated. */
12032 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12033 case will be handled here. */
12037 /* !X && X is always false. */
12041 /* X && !X is always false. */
12046 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12047 means A >= Y && A != MAX, but in this case we know that
12048 A < X <= MAX. */
12052 {
12060 }
12062 truth_andor:
12063 /* We only do these simplifications if we are optimizing. */
12067 /* Check for things like (A || B) && (A || C). We can convert this
12068 to A || (B && C). Note that either operator can be any of the four
12069 truth and/or operations and the transformation will still be
12070 valid. Also note that we only care about order for the
12071 ANDIF and ORIF operators. If B contains side effects, this
12072 might change the truth-value of A. */
12079 {
12099 /* This case if tricky because we must either have commutative
12100 operators or else A10 must not have side-effects. */
12106 a01);
12107 }
12109 /* See if we can build a range comparison. */
12113 /* Check for the possibility of merging component references. If our
12114 lhs is another similar operation, try to merge its rhs with our
12115 rhs. Then try to merge our lhs and rhs. */
12127 /* Note that the operands of this must be ints
12128 and their values must be 0 or true.
12129 ("true" is a fixed value perhaps depending on the language.) */
12130 /* If first arg is constant true, return it. */
12134 /* If either arg is constant zero, drop it. */
12138 /* Preserve sequence points. */
12141 /* If second arg is constant true, result is true, but we must
12142 evaluate first arg. */
12145 /* Likewise for first arg, but note this only occurs here for
12146 TRUTH_OR_EXPR. */
12150 /* !X || X is always true. */
12154 /* X || !X is always true. */
12162 /* If the second arg is constant zero, drop it. */
12165 /* If the second arg is constant true, this is a logical inversion. */
12167 {
12168 /* Only call invert_truthvalue if operand is a truth value. */
12171 else
12174 }
12175 /* Identical arguments cancel to zero. */
12179 /* !X ^ X is always true. */
12184 /* X ^ !X is always true. */
12197 /* bool_var != 0 becomes bool_var. */
12202 /* bool_var == 1 becomes bool_var. */
12207 /* bool_var != 1 becomes !bool_var. */
12212 /* bool_var == 0 becomes !bool_var. */
12217 /* If this is an equality comparison of the address of two non-weak,
12218 unaliased symbols neither of which are extern (since we do not
12219 have access to attributes for externs), then we know the result. */
12232 {
12233 /* We know that we're looking at the address of two
12234 non-weak, unaliased, static _DECL nodes.
12236 It is both wasteful and incorrect to call operand_equal_p
12237 to compare the two ADDR_EXPR nodes. It is wasteful in that
12238 all we need to do is test pointer equality for the arguments
12239 to the two ADDR_EXPR nodes. It is incorrect to use
12240 operand_equal_p as that function is NOT equivalent to a
12241 C equality test. It can in fact return false for two
12242 objects which would test as equal using the C equality
12243 operator. */
12247 type);
12248 }
12250 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12251 a MINUS_EXPR of a constant, we can convert it into a comparison with
12252 a revised constant as long as no overflow occurs. */
12264 /* Similarly for a NEGATE_EXPR. */
12272 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12281 /* Transform comparisons of the form X +- C CMP X. */
12287 {
12294 else
12297 }
12299 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12300 for !=. Don't do this for ordered comparisons due to overflow. */
12306 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12311 /* If this is an EQ or NE comparison with zero and ARG0 is
12312 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12313 two operations, but the latter can be done in one less insn
12314 on machines that have only two-operand insns or on which a
12315 constant cannot be the first operand. */
12318 {
12323 {
12330 }
12333 {
12340 }
12341 }
12343 /* If this is an NE or EQ comparison of zero against the result of a
12344 signed MOD operation whose second operand is a power of 2, make
12345 the MOD operation unsigned since it is simpler and equivalent. */
12353 {
12363 }
12365 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12366 C1 is a valid shift constant, and C2 is a power of two, i.e.
12367 a single bit. */
12371 == INTEGER_CST
12374 {
12379 /* Check for a valid shift count. */
12382 {
12386 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12387 can be rewritten as (X & (C2 << C1)) != 0. */
12389 {
12393 }
12394 /* Otherwise, for signed (arithmetic) shifts,
12395 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12396 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12400 /* Otherwise, of unsigned (logical) shifts,
12401 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12402 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12403 else
12407 arg000);
12408 }
12409 }
12411 /* If this is an NE comparison of zero with an AND of one, remove the
12412 comparison since the AND will give the correct value. */
12419 /* If we have (A & C) == C where C is a power of 2, convert this into
12420 (A & C) != 0. Similarly for NE_EXPR. */
12426 integer_zero_node));
12428 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12429 bit, then fold the expression into A < 0 or A >= 0. */
12434 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12435 Similarly for NE_EXPR. */
12439 {
12448 }
12450 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12451 Similarly for NE_EXPR. */
12455 {
12462 }
12464 /* If this is a comparison of a field, we may be able to simplify it. */
12467 /* Handle the constant case even without -O
12468 to make sure the warnings are given. */
12470 {
12474 }
12476 /* Optimize comparisons of strlen vs zero to a compare of the
12477 first character of the string vs zero. To wit,
12478 strlen(ptr) == 0 => *ptr == 0
12479 strlen(ptr) != 0 => *ptr != 0
12480 Other cases should reduce to one of these two (or a constant)
12481 due to the return value of strlen being unsigned. */
12484 {
12492 {
12496 }
12497 }
12499 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12500 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12504 {
12511 {
12513 {
12516 }
12519 }
12520 }
12522 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12528 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12533 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12540 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12548 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12549 (X & C) == 0 when C is a single bit. */
12554 {
12560 }
12562 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12563 constant C is a power of two, i.e. a single bit. */
12570 {
12574 }
12576 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12577 when is C is a power of two, i.e. a single bit. */
12584 {
12590 }
12594 {
12597 }
12599 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12606 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12609 {
12621 arg01),
12629 arg01),
12637 arg00),
12645 arg00),
12647 }
12651 {
12658 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12659 operand_equal_p guarantees no side-effects so we don't need
12660 to use omit_one_operand on Z. */
12670 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12677 arg10);
12678 }
12680 /* Attempt to simplify equality/inequality comparisons of complex
12681 values. Only lower the comparison if the result is known or
12682 can be simplified to a single scalar comparison. */
12687 {
12692 {
12695 }
12696 else
12697 {
12700 }
12703 {
12706 }
12707 else
12708 {
12711 }
12715 {
12717 {
12722 }
12723 else
12724 {
12729 }
12730 }
12734 {
12736 {
12741 }
12742 else
12743 {
12748 }
12749 }
12750 }
12762 /* Transform comparisons of the form X +- C CMP X. */
12769 {
12776 else
12779 /* (X - c) > X becomes false. */
12783 {
12787 "occur when assuming that (X - c) > X "
12789 WARN_STRICT_OVERFLOW_ALL);
12791 }
12793 /* Likewise (X + c) < X becomes false. */
12797 {
12801 "occur when assuming that "
12803 WARN_STRICT_OVERFLOW_ALL);
12805 }
12807 /* Convert (X - c) <= X to true. */
12812 {
12816 "occur when assuming that "
12818 WARN_STRICT_OVERFLOW_ALL);
12820 }
12822 /* Convert (X + c) >= X to true. */
12827 {
12831 "occur when assuming that "
12833 WARN_STRICT_OVERFLOW_ALL);
12835 }
12838 {
12839 /* Convert X + c > X and X - c < X to true for integers. */
12843 {
12846 "not occur when assuming that "
12848 WARN_STRICT_OVERFLOW_ALL);
12850 }
12855 {
12858 "not occur when assuming that "
12860 WARN_STRICT_OVERFLOW_ALL);
12862 }
12864 /* Convert X + c <= X and X - c >= X to false for integers. */
12868 {
12871 "not occur when assuming that "
12873 WARN_STRICT_OVERFLOW_ALL);
12875 }
12880 {
12883 "not occur when assuming that "
12885 WARN_STRICT_OVERFLOW_ALL);
12887 }
12888 }
12889 }
12891 /* Comparisons with the highest or lowest possible integer of
12892 the specified precision will have known values. */
12893 {
12900 {
12901 HOST_WIDE_INT signed_max_hi;
12906 {
12913 {
12917 }
12918 else
12919 {
12923 }
12924 }
12925 else
12926 {
12935 {
12938 }
12939 else
12940 {
12943 }
12944 }
12949 {
12962 /* The GE_EXPR and LT_EXPR cases above are not normally
12963 reached because of previous transformations. */
12967 }
12969 == max_hi
12972 {
12978 arg1);
12984 arg1);
12987 }
12989 == min_hi
12992 {
13007 }
13009 == min_hi
13012 {
13017 arg1);
13022 arg1);
13025 }
13030 /* We will flip the signedness of the comparison operator
13031 associated with the mode of arg1, so the sign bit is
13032 specified by this mode. Check that arg1 is the signed
13033 max associated with this sign bit. */
13035 /* signed_type does not work on pointer types. */
13037 {
13038 /* The following case also applies to X < signed_max+1
13039 and X >= signed_max+1 because previous transformations. */
13041 {
13042 tree st;
13047 }
13048 }
13049 }
13050 }
13052 /* If we are comparing an ABS_EXPR with a constant, we can
13053 convert all the cases into explicit comparisons, but they may
13054 well not be faster than doing the ABS and one comparison.
13055 But ABS (X) <= C is a range comparison, which becomes a subtraction
13056 and a comparison, and is probably faster. */
13070 /* Convert ABS_EXPR<x> >= 0 to true. */
13077 {
13080 "when simplifying comparison of "
13082 WARN_STRICT_OVERFLOW_CONDITIONAL);
13084 }
13086 /* Convert ABS_EXPR<x> < 0 to false. */
13091 {
13094 "when simplifying comparison of "
13096 WARN_STRICT_OVERFLOW_CONDITIONAL);
13098 }
13100 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13101 and similarly for >= into !=. */
13116 return
13135 {
13139 }
13141 /* If the first operand is NaN, the result is constant. */
13145 {
13147 ? integer_zero_node
13150 }
13152 /* If the second operand is NaN, the result is constant. */
13156 {
13158 ? integer_zero_node
13161 }
13163 /* Simplify unordered comparison of something with itself. */
13169 && !flag_trapping_math
13173 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13174 {
13185 }
13190 /* When pedantic, a compound expression can be neither an lvalue
13191 nor an integer constant expression. */
13194 /* Don't let (0, 0) be null pointer constant. */
13208 /* An ASSERT_EXPR should never be passed to fold_binary. */
13214 }
13216 /* Callback for walk_tree, looking for LABEL_EXPR.
13217 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13218 Do not check the sub-tree of GOTO_EXPR. */
13220 static tree
13224 {
13226 {
13231 /* no break */
13234 }
13235 }
13237 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13238 accessible from outside the sub-tree. Returns NULL_TREE if no
13239 addressable label is found. */
13241 static bool
13243 {
13245 }
13247 /* Fold a ternary expression of code CODE and type TYPE with operands
13248 OP0, OP1, and OP2. Return the folded expression if folding is
13249 successful. Otherwise, return NULL_TREE. */
13251 tree
13253 {
13254 tree tem;
13261 /* Strip any conversions that don't change the mode. This is safe
13262 for every expression, except for a comparison expression because
13263 its signedness is derived from its operands. So, in the latter
13264 case, only strip conversions that don't change the signedness.
13266 Note that this is done as an internal manipulation within the
13267 constant folder, in order to find the simplest representation of
13268 the arguments so that their form can be studied. In any cases,
13269 the appropriate type conversions should be put back in the tree
13270 that will get out of the constant folder. */
13272 {
13275 }
13278 {
13281 }
13284 {
13288 {
13294 }
13298 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13299 so all simple results must be passed through pedantic_non_lvalue. */
13301 {
13304 /* Only optimize constant conditions when the selected branch
13305 has the same type as the COND_EXPR. This avoids optimizing
13306 away "c ? x : throw", where the throw has a void type.
13307 Avoid throwing away that operand which contains label. */
13314 }
13318 /* If we have A op B ? A : C, we may be able to convert this to a
13319 simpler expression, depending on the operation and the values
13320 of B and C. Signed zeros prevent all of these transformations,
13321 for reasons given above each one.
13323 Also try swapping the arguments and inverting the conditional. */
13328 {
13332 }
13336 op2,
13339 {
13342 {
13346 }
13347 }
13349 /* If the second operand is simpler than the third, swap them
13350 since that produces better jump optimization results. */
13353 {
13354 /* See if this can be inverted. If it can't, possibly because
13355 it was a floating-point inequality comparison, don't do
13356 anything. */
13360 }
13362 /* Convert A ? 1 : 0 to simply A. */
13365 /* If we try to convert OP0 to our type, the
13366 call to fold will try to move the conversion inside
13367 a COND, which will recurse. In that case, the COND_EXPR
13368 is probably the best choice, so leave it alone. */
13372 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13373 over COND_EXPR in cases such as floating point comparisons. */
13380 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13385 {
13386 /* sign_bit_p only checks ARG1 bits within A's precision.
13387 If <sign bit of A> has wider type than A, bits outside
13388 of A's precision in <sign bit of A> need to be checked.
13389 If they are all 0, this optimization needs to be done
13390 in unsigned A's type, if they are all 1 in signed A's type,
13391 otherwise this can't be done. */
13396 {
13398 HOST_WIDE_INT mask_hi;
13400 tree tem_type;
13408 {
13412 }
13413 else
13414 {
13418 }
13420 {
13424 }
13425 else
13431 {
13434 }
13437 {
13440 }
13441 else
13443 }
13450 arg1)));
13451 }
13453 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13454 already handled above. */
13459 {
13468 }
13470 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13471 is probably obsolete because the first operand should be a
13472 truth value (that's why we have the two cases above), but let's
13473 leave it in until we can confirm this for all front-ends. */
13484 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13490 arg1);
13492 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13496 {
13497 /* Only perform transformation if ARG0 is easily inverted. */
13502 arg1);
13503 }
13505 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13509 {
13510 /* Only perform transformation if ARG0 is easily inverted. */
13515 op2);
13516 }
13518 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13524 op2);
13529 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13530 of fold_ternary on them. */
13537 {
13546 {
13551 else
13552 {
13554 tree value;
13558 }
13563 else
13565 }
13566 }
13568 /* A bit-field-ref that referenced the full argument can be stripped. */
13579 }
13581 /* Perform constant folding and related simplification of EXPR.
13582 The related simplifications include x*1 => x, x*0 => 0, etc.,
13583 and application of the associative law.
13584 NOP_EXPR conversions may be removed freely (as long as we
13585 are careful not to change the type of the overall expression).
13586 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13587 but we can constant-fold them if they have constant operands. */
13589 #ifdef ENABLE_FOLD_CHECKING
13590 # define fold(x) fold_1 (x)
13592 static
13593 #endif
13594 tree
13596 {
13600 tree tem;
13602 /* Return right away if a constant. */
13606 /* CALL_EXPR-like objects with variable numbers of operands are
13607 treated specially. */
13609 {
13611 {
13614 }
13616 }
13619 {
13624 {
13642 }
13643 }
13646 {
13648 {
13655 {
13660 /* Find a matching index by means of a binary search. */
13662 {
13678 else
13680 }
13681 }
13684 }
13692 }
13694 #ifdef ENABLE_FOLD_CHECKING
13695 #undef fold
13701 /* When --enable-checking=fold, compute a digest of expr before
13702 and after actual fold call to see if fold did not accidentally
13703 change original expr. */
13705 tree
13707 {
13708 tree ret;
13711 htab_t ht;
13730 }
13732 void
13734 {
13737 htab_t ht;
13747 }
13749 static void
13751 {
13753 }
13755 static void
13757 {
13763 recursive_label:
13777 {
13778 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13782 }
13789 {
13790 /* Allow these fields to be modified. */
13791 tree tmp;
13799 {
13802 }
13803 }
13812 {
13815 {
13829 }
13833 {
13846 }
13863 {
13869 }
13874 {
13878 }
13889 {
13892 }
13902 }
13903 }
13905 /* Helper function for outputting the checksum of a tree T. When
13906 debugging with gdb, you can "define mynext" to be "next" followed
13907 by "call debug_fold_checksum (op0)", then just trace down till the
13908 outputs differ. */
13910 void
13912 {
13927 }
13929 #endif
13931 /* Fold a unary tree expression with code CODE of type TYPE with an
13932 operand OP0. Return a folded expression if successful. Otherwise,
13933 return a tree expression with code CODE of type TYPE with an
13934 operand OP0. */
13936 tree
13938 {
13939 tree tem;
13940 #ifdef ENABLE_FOLD_CHECKING
13943 htab_t ht;
13950 #endif
13956 #ifdef ENABLE_FOLD_CHECKING
13964 #endif
13966 }
13968 /* Fold a binary tree expression with code CODE of type TYPE with
13969 operands OP0 and OP1. Return a folded expression if successful.
13970 Otherwise, return a tree expression with code CODE of type TYPE
13971 with operands OP0 and OP1. */
13973 tree
13975 MEM_STAT_DECL)
13976 {
13977 tree tem;
13978 #ifdef ENABLE_FOLD_CHECKING
13984 htab_t ht;
13996 #endif
14002 #ifdef ENABLE_FOLD_CHECKING
14018 #endif
14020 }
14022 /* Fold a ternary tree expression with code CODE of type TYPE with
14023 operands OP0, OP1, and OP2. Return a folded expression if
14024 successful. Otherwise, return a tree expression with code CODE of
14025 type TYPE with operands OP0, OP1, and OP2. */
14027 tree
14029 MEM_STAT_DECL)
14030 {
14031 tree tem;
14032 #ifdef ENABLE_FOLD_CHECKING
14040 htab_t ht;
14057 #endif
14064 #ifdef ENABLE_FOLD_CHECKING
14088 #endif
14090 }
14092 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14093 arguments in ARGARRAY, and a null static chain.
14094 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14095 of type TYPE from the given operands as constructed by build_call_array. */
14097 tree
14099 {
14100 tree tem;
14101 #ifdef ENABLE_FOLD_CHECKING
14107 htab_t ht;
14121 #endif
14125 #ifdef ENABLE_FOLD_CHECKING
14142 #endif
14144 }
14146 /* Perform constant folding and related simplification of initializer
14147 expression EXPR. These behave identically to "fold_buildN" but ignore
14148 potential run-time traps and exceptions that fold must preserve. */
14150 #define START_FOLD_INIT \
14151 int saved_signaling_nans = flag_signaling_nans;\
14152 int saved_trapping_math = flag_trapping_math;\
14153 int saved_rounding_math = flag_rounding_math;\
14154 int saved_trapv = flag_trapv;\
14155 int saved_folding_initializer = folding_initializer;\
14156 flag_signaling_nans = 0;\
14157 flag_trapping_math = 0;\
14158 flag_rounding_math = 0;\
14159 flag_trapv = 0;\
14160 folding_initializer = 1;
14162 #define END_FOLD_INIT \
14163 flag_signaling_nans = saved_signaling_nans;\
14164 flag_trapping_math = saved_trapping_math;\
14165 flag_rounding_math = saved_rounding_math;\
14166 flag_trapv = saved_trapv;\
14167 folding_initializer = saved_folding_initializer;
14169 tree
14171 {
14172 tree result;
14173 START_FOLD_INIT;
14177 END_FOLD_INIT;
14179 }
14181 tree
14183 {
14184 tree result;
14185 START_FOLD_INIT;
14189 END_FOLD_INIT;
14191 }
14193 tree
14195 tree op2)
14196 {
14197 tree result;
14198 START_FOLD_INIT;
14202 END_FOLD_INIT;
14204 }
14206 tree
14209 {
14210 tree result;
14211 START_FOLD_INIT;
14215 END_FOLD_INIT;
14217 }
14219 #undef START_FOLD_INIT
14220 #undef END_FOLD_INIT
14222 /* Determine if first argument is a multiple of second argument. Return 0 if
14223 it is not, or we cannot easily determined it to be.
14225 An example of the sort of thing we care about (at this point; this routine
14226 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14227 fold cases do now) is discovering that
14229 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14231 is a multiple of
14233 SAVE_EXPR (J * 8)
14235 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14237 This code also handles discovering that
14239 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14241 is a multiple of 8 so we don't have to worry about dealing with a
14242 possible remainder.
14244 Note that we *look* inside a SAVE_EXPR only to determine how it was
14245 calculated; it is not safe for fold to do much of anything else with the
14246 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14247 at run time. For example, the latter example above *cannot* be implemented
14248 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14249 evaluation time of the original SAVE_EXPR is not necessarily the same at
14250 the time the new expression is evaluated. The only optimization of this
14251 sort that would be valid is changing
14253 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14255 divided by 8 to
14257 SAVE_EXPR (I) * SAVE_EXPR (J)
14259 (where the same SAVE_EXPR (J) is used in the original and the
14260 transformed version). */
14262 int
14264 {
14272 {
14274 /* Bitwise and provides a power of two multiple. If the mask is
14275 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14278 /* FALLTHRU */
14291 {
14295 /* const_binop may not detect overflow correctly,
14296 so check for it explicitly here. */
14302 size_one_node,
14306 }
14310 /* Can't handle conversions from non-integral or wider integral type. */
14316 /* .. fall through ... */
14333 }
14334 }
14336 /* Return true if CODE or TYPE is known to be non-negative. */
14338 static bool
14340 {
14343 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14344 have a signed:1 type (where the value is -1 and 0). */
14347 }
14349 /* Return true if (CODE OP0) is known to be non-negative. If the return
14350 value is based on the assumption that signed overflow is undefined,
14351 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14352 *STRICT_OVERFLOW_P. */
14354 bool
14357 {
14362 {
14364 /* We can't return 1 if flag_wrapv is set because
14365 ABS_EXPR<INT_MIN> = INT_MIN. */
14369 {
14372 }
14379 strict_overflow_p);
14382 {
14387 {
14390 strict_overflow_p);
14392 {
14396 strict_overflow_p);
14397 }
14398 }
14400 {
14403 strict_overflow_p);
14407 }
14408 }
14413 }
14415 /* We don't know sign of `t', so be conservative and return false. */
14417 }
14419 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14420 value is based on the assumption that signed overflow is undefined,
14421 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14422 *STRICT_OVERFLOW_P. */
14424 bool
14427 {
14432 {
14437 strict_overflow_p)
14439 strict_overflow_p));
14441 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14442 both unsigned and at least 2 bits shorter than the result. */
14446 {
14451 {
14455 }
14456 }
14461 {
14462 /* x * x for floating point x is always non-negative. */
14466 strict_overflow_p)
14468 strict_overflow_p));
14469 }
14471 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14472 both unsigned and their total bits is shorter than the result. */
14476 {
14495 {
14505 }
14506 }
14512 strict_overflow_p)
14514 strict_overflow_p));
14525 strict_overflow_p)
14527 strict_overflow_p));
14534 strict_overflow_p);
14537 }
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
14550 {
14555 {
14567 strict_overflow_p)
14569 strict_overflow_p));
14573 }
14574 /* We don't know sign of `t', so be conservative and return false. */
14576 }
14578 /* Return true if T is known to be non-negative. If the return
14579 value is based on the assumption that signed overflow is undefined,
14580 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14581 *STRICT_OVERFLOW_P. */
14583 bool
14586 {
14589 {
14607 /* Always true. */
14611 /* sqrt(-0.0) is -0.0. */
14615 strict_overflow_p);
14648 /* True if the 1st argument is nonnegative. */
14650 strict_overflow_p);
14653 /* True if the 1st OR 2nd arguments are nonnegative. */
14655 strict_overflow_p)
14657 strict_overflow_p)));
14660 /* True if the 1st AND 2nd arguments are nonnegative. */
14662 strict_overflow_p)
14664 strict_overflow_p)));
14667 /* True if the 2nd argument is nonnegative. */
14669 strict_overflow_p);
14672 /* True if the 1st argument is nonnegative or the second
14673 argument is an even integer. */
14678 strict_overflow_p);
14681 /* True if the 1st argument is nonnegative or the second
14682 argument is an even integer valued real. */
14684 {
14685 REAL_VALUE_TYPE c;
14686 HOST_WIDE_INT n;
14691 {
14692 REAL_VALUE_TYPE cint;
14697 }
14698 }
14700 strict_overflow_p);
14704 }
14706 type);
14707 }
14709 /* Return true if T is known to be non-negative. If the return
14710 value is based on the assumption that signed overflow is undefined,
14711 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14712 *STRICT_OVERFLOW_P. */
14714 bool
14716 {
14722 {
14724 {
14728 /* If the initializer is non-void, then it's a normal expression
14729 that will be assigned to the slot. */
14733 /* Otherwise, the initializer sets the slot in some way. One common
14734 way is an assignment statement at the end of the initializer. */
14736 {
14744 else
14746 }
14750 strict_overflow_p);
14753 }
14756 {
14762 arg0,
14763 arg1,
14764 strict_overflow_p);
14765 }
14769 strict_overflow_p);
14772 strict_overflow_p);
14775 strict_overflow_p);
14780 }
14782 /* We don't know sign of `t', so be conservative and return false. */
14784 }
14786 /* Return true if T is known to be non-negative. If the return
14787 value is based on the assumption that signed overflow is undefined,
14788 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14789 *STRICT_OVERFLOW_P. */
14791 bool
14793 {
14800 {
14807 strict_overflow_p);
14813 strict_overflow_p);
14822 }
14825 {
14833 strict_overflow_p);
14838 strict_overflow_p);
14853 }
14854 }
14856 /* Return true if `t' is known to be non-negative. Handle warnings
14857 about undefined signed overflow. */
14859 bool
14861 {
14868 "determining that expression is always "
14870 WARN_STRICT_OVERFLOW_MISC);
14872 }
14875 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14876 For floating point we further ensure that T is not denormal.
14877 Similar logic is present in nonzero_address in rtlanal.h.
14879 If the return value is based on the assumption that signed overflow
14880 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14881 change *STRICT_OVERFLOW_P. */
14883 bool
14886 {
14888 {
14891 strict_overflow_p);
14894 {
14900 strict_overflow_p));
14901 }
14906 strict_overflow_p);
14910 }
14913 }
14915 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14916 For floating point we further ensure that T is not denormal.
14917 Similar logic is present in nonzero_address in rtlanal.h.
14919 If the return value is based on the assumption that signed overflow
14920 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14921 change *STRICT_OVERFLOW_P. */
14923 bool
14925 tree type ATTRIBUTE_UNUSED,
14926 tree op0,
14928 {
14931 {
14935 {
14936 /* With the presence of negative values it is hard
14937 to say something. */
14944 /* One of operands must be positive and the other non-negative. */
14945 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14946 overflows, on a twos-complement machine the sum of two
14947 nonnegative numbers can never be zero. */
14949 strict_overflow_p)
14951 strict_overflow_p));
14952 }
14957 {
14959 strict_overflow_p)
14961 strict_overflow_p))
14962 {
14965 }
14966 }
14975 {
14978 }
14985 {
14989 /* When both operands are nonzero, then MAX must be too. */
14991 strict_overflow_p))
14994 /* MAX where operand 0 is positive is positive. */
14996 strict_overflow_p);
14997 }
14998 /* MAX where operand 1 is positive is positive. */
15003 {
15007 }
15012 strict_overflow_p)
15014 strict_overflow_p));
15018 }
15021 }
15023 /* Return true when T is an address and is known to be nonzero.
15024 For floating point we further ensure that T is not denormal.
15025 Similar logic is present in nonzero_address in rtlanal.h.
15027 If the return value is based on the assumption that signed overflow
15028 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15029 change *STRICT_OVERFLOW_P. */
15031 bool
15033 {
15036 {
15041 {
15047 /* Weak declarations may link to NULL. */
15051 /* Constants are never weak. */
15056 }
15064 {
15068 }
15073 }
15075 }
15077 /* Return true when T is an address and is known to be nonzero.
15078 For floating point we further ensure that T is not denormal.
15079 Similar logic is present in nonzero_address in rtlanal.h.
15081 If the return value is based on the assumption that signed overflow
15082 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15083 change *STRICT_OVERFLOW_P. */
15085 bool
15087 {
15091 /* Doing something useful for floating point would need more work. */
15097 {
15100 strict_overflow_p);
15106 strict_overflow_p);
15114 }
15117 {
15120 strict_overflow_p);
15128 strict_overflow_p);
15145 strict_overflow_p);
15149 strict_overflow_p);
15156 }
15158 }
15160 /* Return true when T is an address and is known to be nonzero.
15161 Handle warnings about undefined signed overflow. */
15163 bool
15165 {
15172 "determining that expression is always "
15174 WARN_STRICT_OVERFLOW_MISC);
15176 }
15178 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15179 attempt to fold the expression to a constant without modifying TYPE,
15180 OP0 or OP1.
15182 If the expression could be simplified to a constant, then return
15183 the constant. If the expression would not be simplified to a
15184 constant, then return NULL_TREE. */
15186 tree
15188 {
15191 }
15193 /* Given the components of a unary expression CODE, TYPE and OP0,
15194 attempt to fold the expression to a constant without modifying
15195 TYPE or OP0.
15197 If the expression could be simplified to a constant, then return
15198 the constant. If the expression would not be simplified to a
15199 constant, then return NULL_TREE. */
15201 tree
15203 {
15206 }
15208 /* If EXP represents referencing an element in a constant string
15209 (either via pointer arithmetic or array indexing), return the
15210 tree representing the value accessed, otherwise return NULL. */
15212 tree
15214 {
15218 {
15220 tree index;
15221 tree string;
15225 else
15226 {
15230 /* Optimize the special-case of a zero lower bound.
15232 We convert the low_bound to sizetype to avoid some problems
15233 with constant folding. (E.g. suppose the lower bound is 1,
15234 and its mode is QI. Without the conversion,l (ARRAY
15235 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15236 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15241 }
15254 }
15256 }
15258 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15259 an integer constant, real, or fixed-point constant.
15261 TYPE is the type of the result. */
15263 static tree
15265 {
15269 {
15271 {
15273 HOST_WIDE_INT high;
15281 }
15288 {
15289 FIXED_VALUE_TYPE f;
15294 /* Propagate overflow flags. */
15296 {
15299 }
15303 }
15307 }
15310 }
15312 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15313 an integer constant or real constant.
15315 TYPE is the type of the result. */
15317 tree
15319 {
15323 {
15325 /* If the value is unsigned, then the absolute value is
15326 the same as the ordinary value. */
15329 /* Similarly, if the value is non-negative. */
15332 /* If the value is negative, then the absolute value is
15333 its negation. */
15334 else
15335 {
15337 HOST_WIDE_INT high;
15343 }
15349 else
15355 }
15358 }
15360 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15361 constant. TYPE is the type of the result. */
15363 static tree
15365 {
15375 }
15377 /* Given CODE, a relational operator, the target type, TYPE and two
15378 constant operands OP0 and OP1, return the result of the
15379 relational operation. If the result is not a compile time
15380 constant, then return NULL_TREE. */
15382 static tree
15384 {
15387 /* From here on, the only cases we handle are when the result is
15388 known to be a constant. */
15391 {
15395 /* Handle the cases where either operand is a NaN. */
15397 {
15399 {
15427 }
15430 }
15433 }
15436 {
15440 }
15442 /* Handle equality/inequality of complex constants. */
15444 {
15455 else
15457 }
15459 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15461 To compute GT, swap the arguments and do LT.
15462 To compute GE, do LT and invert the result.
15463 To compute LE, swap the arguments, do LT and invert the result.
15464 To compute NE, do EQ and invert the result.
15466 Therefore, the code below must handle only EQ and LT. */
15469 {
15474 }
15476 /* Note that it is safe to invert for real values here because we
15477 have already handled the one case that it matters. */
15481 {
15484 }
15486 /* Compute a result for LT or EQ if args permit;
15487 Otherwise return T. */
15489 {
15494 else
15496 }
15497 else
15503 }
15505 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15506 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15507 itself. */
15509 tree
15511 {
15512 /* If the expression does not have side effects then we don't have to wrap
15513 it with a cleanup point expression. */
15517 /* If the expression is a return, check to see if the expression inside the
15518 return has no side effects or the right hand side of the modify expression
15519 inside the return. If either don't have side effects set we don't need to
15520 wrap the expression in a cleanup point expression. Note we don't check the
15521 left hand side of the modify because it should always be a return decl. */
15523 {
15530 }
15533 }
15535 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15536 of an indirection through OP0, or NULL_TREE if no simplification is
15537 possible. */
15539 tree
15541 {
15543 tree subtype;
15551 {
15554 /* *&CONST_DECL -> to the value of the const decl. */
15557 /* *&p => p; make sure to handle *&"str"[cst] here. */
15559 {
15563 else
15565 }
15566 /* *(foo *)&fooarray => fooarray[0] */
15569 {
15575 }
15576 /* *(foo *)&complexfoo => __real__ complexfoo */
15580 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15583 {
15587 }
15588 }
15590 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15593 {
15596 tree op00type;
15603 {
15614 }
15615 }
15618 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15621 {
15624 tree op00type;
15631 {
15635 }
15636 }
15638 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15641 {
15642 tree type_domain;
15649 }
15652 }
15654 /* Builds an expression for an indirection through T, simplifying some
15655 cases. */
15657 tree
15659 {
15665 else
15667 }
15669 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15671 tree
15673 {
15678 else
15680 }
15682 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15683 whose result is ignored. The type of the returned tree need not be
15684 the same as the original expression. */
15686 tree
15688 {
15694 {
15705 else
15711 {
15727 }
15732 }
15733 }
15735 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15736 This can only be applied to objects of a sizetype. */
15738 tree
15740 {
15747 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15748 have to do anything. Only do this when we are not given a const,
15749 because in that case, this check is more expensive than just
15750 doing it. */
15752 {
15757 }
15759 /* If divisor is a power of two, simplify this to bit manipulation. */
15761 {
15763 {
15776 {
15777 high++;
15780 }
15784 }
15785 else
15786 {
15787 tree t;
15793 }
15794 }
15795 else
15796 {
15801 }
15804 }
15806 /* Likewise, but round down. */
15808 tree
15810 {
15817 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15818 have to do anything. Only do this when we are not given a const,
15819 because in that case, this check is more expensive than just
15820 doing it. */
15822 {
15827 }
15829 /* If divisor is a power of two, simplify this to bit manipulation. */
15831 {
15832 tree t;
15836 }
15837 else
15838 {
15843 }
15846 }
15848 /* Returns the pointer to the base of the object addressed by EXP and
15849 extracts the information about the offset of the access, storing it
15850 to PBITPOS and POFFSET. */
15852 static tree
15855 {
15856 tree core;
15859 HOST_WIDE_INT bitsize;
15862 {
15867 }
15868 else
15869 {
15873 }
15876 }
15878 /* Returns true if addresses of E1 and E2 differ by a constant, false
15879 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15881 bool
15883 {
15897 {
15907 }
15909 {
15910 /* If only one of the offsets is non-constant, the difference cannot
15911 be a constant. */
15913 }
15914 else
15919 }
15921 /* Simplify the floating point expression EXP when the sign of the
15922 result is not significant. Return NULL_TREE if no simplification
15923 is possible. */
15925 tree
15927 {
15931 {
15966 {
15969 {
15971 /* Strip copysign function call, return the 1st argument. */
15977 /* Strip sign ops from the argument of "odd" math functions. */
15979 {
15983 }
15985 }
15986 }
15991 }
15993 }