| blob | c8e2f514c7181e754a079be899ed29e24f5c30b9 |
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
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 2, 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 COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
21 02110-1301, USA. */
23 /*@@ This file should be rewritten to use an arbitrary precision
24 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
25 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
26 @@ The routines that translate from the ap rep should
27 @@ warn if precision et. al. is lost.
28 @@ This would also make life easier when this technology is used
29 @@ for cross-compilers. */
31 /* The entry points in this file are fold, size_int_wide, size_binop
32 and force_fit_type_double.
34 fold takes a tree as argument and returns a simplified tree.
36 size_binop takes a tree code for an arithmetic operation
37 and two operands that are trees, and produces a tree for the
38 result, assuming the type comes from `sizetype'.
40 size_int takes an integer value, and creates a tree constant
41 with type from `sizetype'.
43 force_fit_type_double takes a constant, an overflowable flag and a
44 prior overflow indicator. It forces the value to fit the type and
45 sets TREE_OVERFLOW.
47 Note: Since the folders get called on non-gimple code as well as
48 gimple code, we need to handle GIMPLE tuples as well as their
49 corresponding tree equivalents. */
68 /* Non-zero if we are folding constants inside an initializer; zero
69 otherwise. */
72 /* The following constants represent a bit based encoding of GCC's
73 comparison operators. This encoding simplifies transformations
74 on relational comparison operators, such as AND and OR. */
92 };
126 tree);
151 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
152 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
153 and SUM1. Then this yields nonzero if overflow occurred during the
154 addition.
156 Overflow occurs if A and B have the same sign, but A and SUM differ in
157 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
158 sign. */
159 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
160 \f
161 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
162 We do that by representing the two-word integer in 4 words, with only
163 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
164 number. The value of the word is LOWPART + HIGHPART * BASE. */
166 #define LOWPART(x) \
167 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
168 #define HIGHPART(x) \
169 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
170 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
172 /* Unpack a two-word integer into 4 words.
173 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
174 WORDS points to the array of HOST_WIDE_INTs. */
176 static void
178 {
183 }
185 /* Pack an array of 4 words into a two-word integer.
186 WORDS points to the array of words.
187 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
189 static void
192 {
195 }
196 \f
197 /* Force the double-word integer L1, H1 to be within the range of the
198 integer type TYPE. Stores the properly truncated and sign-extended
199 double-word integer in *LV, *HV. Returns true if the operation
200 overflows, that is, argument and result are different. */
202 int
205 {
214 else
217 /* Size types *are* sign extended. */
222 /* First clear all bits that are beyond the type's precision. */
224 ;
227 else
228 {
232 }
234 /* Then do sign extension if necessary. */
240 {
241 /* Sign extend top half? */
245 }
247 {
250 }
251 else
252 {
253 /* Sign extend bottom half? */
255 {
258 }
259 }
264 /* If the value didn't fit, signal overflow. */
266 }
268 /* We force the double-int HIGH:LOW to the range of the type TYPE by
269 sign or zero extending it.
270 OVERFLOWABLE indicates if we are interested
271 in overflow of the value, when >0 we are only interested in signed
272 overflow, for <0 we are interested in any overflow. OVERFLOWED
273 indicates whether overflow has already occurred. CONST_OVERFLOWED
274 indicates whether constant overflow has already occurred. We force
275 T's value to be within range of T's type (by setting to 0 or 1 all
276 the bits outside the type's range). We set TREE_OVERFLOWED if,
277 OVERFLOWED is nonzero,
278 or OVERFLOWABLE is >0 and signed overflow occurs
279 or OVERFLOWABLE is <0 and any overflow occurs
280 We return a new tree node for the extended double-int. The node
281 is shared if no overflow flags are set. */
283 tree
287 {
291 /* Size types *are* sign extended. */
298 /* If we need to set overflow flags, return a new unshared node. */
300 {
304 {
311 }
312 }
314 /* Else build a shared node. */
316 }
317 \f
318 /* Add two doubleword integers with doubleword result.
319 Return nonzero if the operation overflows according to UNSIGNED_P.
320 Each argument is given as two `HOST_WIDE_INT' pieces.
321 One argument is L1 and H1; the other, L2 and H2.
322 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
324 int
329 {
331 HOST_WIDE_INT h;
341 else
343 }
345 /* Negate a doubleword integer with doubleword result.
346 Return nonzero if the operation overflows, assuming it's signed.
347 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
348 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
350 int
353 {
355 {
359 }
360 else
361 {
365 }
366 }
367 \f
368 /* Multiply two doubleword integers with doubleword result.
369 Return nonzero if the operation overflows according to UNSIGNED_P.
370 Each argument is given as two `HOST_WIDE_INT' pieces.
371 One argument is L1 and H1; the other, L2 and H2.
372 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
374 int
379 {
394 {
397 {
399 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
401 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
405 }
407 }
412 /* Unsigned overflow is immediate. */
416 /* Check for signed overflow by calculating the signed representation of the
417 top half of the result; it should agree with the low half's sign bit. */
419 {
422 }
424 {
427 }
429 }
430 \f
431 /* Shift the doubleword integer in L1, H1 left by COUNT places
432 keeping only PREC bits of result.
433 Shift right if COUNT is negative.
434 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
435 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
437 void
441 {
445 {
448 }
454 {
455 /* Shifting by the host word size is undefined according to the
456 ANSI standard, so we must handle this as a special case. */
459 }
461 {
464 }
465 else
466 {
470 }
472 /* Sign extend all bits that are beyond the precision. */
480 ;
482 {
485 }
486 else
487 {
491 }
492 }
494 /* Shift the doubleword integer in L1, H1 right by COUNT places
495 keeping only PREC bits of result. COUNT must be positive.
496 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
497 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
499 void
504 {
507 signmask = (arith
515 {
516 /* Shifting by the host word size is undefined according to the
517 ANSI standard, so we must handle this as a special case. */
520 }
522 {
525 }
526 else
527 {
531 }
533 /* Zero / sign extend all bits that are beyond the precision. */
536 {
539 }
541 ;
543 {
546 }
547 else
548 {
552 }
553 }
554 \f
555 /* Rotate the doubleword integer in L1, H1 left by COUNT places
556 keeping only PREC bits of result.
557 Rotate right if COUNT is negative.
558 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
560 void
564 {
576 }
578 /* Rotate the doubleword integer in L1, H1 left by COUNT places
579 keeping only PREC bits of result. COUNT must be positive.
580 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
582 void
586 {
598 }
599 \f
600 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
601 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
602 CODE is a tree code for a kind of division, one of
603 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
604 or EXACT_DIV_EXPR
605 It controls how the quotient is rounded to an integer.
606 Return nonzero if the operation overflows.
607 UNS nonzero says do unsigned division. */
609 int
612 HOST_WIDE_INT hnum_orig,
614 HOST_WIDE_INT hden_orig,
618 {
634 /* Calculate quotient sign and convert operands to unsigned. */
636 {
638 {
640 /* (minimum integer) / (-1) is the only overflow case. */
644 }
646 {
649 }
650 }
655 /* This unsigned division rounds toward zero. */
658 }
662 /* hden != 0 already checked. */
667 }
677 /* Special code for when the divisor < BASE. */
679 {
680 /* hnum != 0 already checked. */
682 {
686 }
687 }
688 else
689 {
690 /* Full double precision division,
691 with thanks to Don Knuth's "Seminumerical Algorithms". */
695 /* Find the highest nonzero divisor digit. */
698 {
701 }
703 /* Insure that the first digit of the divisor is at least BASE/2.
704 This is required by the quotient digit estimation algorithm. */
711 {
715 }
720 {
725 }
726 }
730 /* Main loop */
732 {
733 /* Guess the next quotient digit, quo_est, by dividing the first
734 two remaining dividend digits by the high order quotient digit.
735 quo_est is never low and is at most 2 high. */
742 else
745 /* Refine quo_est so it's usually correct, and at most one high. */
750 quo_est--;
752 /* Try QUO_EST as the quotient digit, by multiplying the
753 divisor by QUO_EST and subtracting from the remaining dividend.
754 Keep in mind that QUO_EST is the I - 1st digit. */
758 {
764 }
766 /* If quo_est was high by one, then num[i] went negative and
767 we need to correct things. */
769 {
770 quo_est--;
773 {
777 }
780 }
782 /* Store the quotient digit. */
784 }
785 }
789 finish_up:
790 /* If result is negative, make it so. */
794 /* Compute trial remainder: rem = num - (quo * den) */
800 {
809 {
810 /* quo = quo - 1; */
813 }
814 else
821 {
824 }
825 else
831 {
837 /* Get absolute values. */
843 /* If (2 * abs (lrem) >= abs (lden)) */
852 {
854 /* quo = quo - 1; */
857 else
858 /* quo = quo + 1; */
861 }
862 else
864 }
869 }
871 /* Compute true remainder: rem = num - (quo * den) */
876 }
878 /* If ARG2 divides ARG1 with zero remainder, carries out the division
879 of type CODE and returns the quotient.
880 Otherwise returns NULL_TREE. */
882 static tree
884 {
903 }
904 \f
905 /* This is non-zero if we should defer warnings about undefined
906 overflow. This facility exists because these warnings are a
907 special case. The code to estimate loop iterations does not want
908 to issue any warnings, since it works with expressions which do not
909 occur in user code. Various bits of cleanup code call fold(), but
910 only use the result if it has certain characteristics (e.g., is a
911 constant); that code only wants to issue a warning if the result is
912 used. */
916 /* If a warning about undefined overflow is deferred, this is the
917 warning. Note that this may cause us to turn two warnings into
918 one, but that is fine since it is sufficient to only give one
919 warning per expression. */
923 /* If a warning about undefined overflow is deferred, this is the
924 level at which the warning should be emitted. */
928 /* Start deferring overflow warnings. We could use a stack here to
929 permit nested calls, but at present it is not necessary. */
931 void
933 {
935 }
937 /* Stop deferring overflow warnings. If there is a pending warning,
938 and ISSUE is true, then issue the warning if appropriate. STMT is
939 the statement with which the warning should be associated (used for
940 location information); STMT may be NULL. CODE is the level of the
941 warning--a warn_strict_overflow_code value. This function will use
942 the smaller of CODE and the deferred code when deciding whether to
943 issue the warning. CODE may be zero to mean to always use the
944 deferred code. */
946 void
948 {
950 location_t locus;
955 {
961 }
969 /* Use the smallest code level when deciding to issue the
970 warning. */
979 else
982 }
984 /* Stop deferring overflow warnings, ignoring any deferred
985 warnings. */
987 void
989 {
991 }
993 /* Whether we are deferring overflow warnings. */
995 bool
997 {
999 }
1001 /* This is called when we fold something based on the fact that signed
1002 overflow is undefined. */
1004 static void
1006 {
1009 {
1012 {
1015 }
1016 }
1019 }
1020 \f
1021 /* Return true if the built-in mathematical function specified by CODE
1022 is odd, i.e. -f(x) == f(-x). */
1024 static bool
1026 {
1028 {
1062 }
1064 }
1066 /* Check whether we may negate an integer constant T without causing
1067 overflow. */
1069 bool
1071 {
1074 tree type;
1084 {
1089 }
1090 else
1095 }
1097 /* Determine whether an expression T can be cheaply negated using
1098 the function negate_expr without introducing undefined overflow. */
1100 static bool
1102 {
1103 tree type;
1112 {
1117 /* Check that -CST will not overflow type. */
1142 /* -(A + B) -> (-B) - A. */
1147 /* -(A + B) -> (-A) - B. */
1151 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1161 /* Fall through. */
1174 /* In general we can't negate A / B, because if A is INT_MIN and
1175 B is 1, we may turn this into INT_MIN / -1 which is undefined
1176 and actually traps on some architectures. But if overflow is
1177 undefined, we can negate, because - (INT_MIN / 1) is an
1178 overflow. */
1186 /* Negate -((double)float) as (double)(-float). */
1188 {
1192 }
1196 /* Negate -f(x) as f(-x). */
1202 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1204 {
1210 }
1215 }
1217 }
1219 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1220 simplification is possible.
1221 If negate_expr_p would return true for T, NULL_TREE will never be
1222 returned. */
1224 static tree
1226 {
1228 tree tem;
1231 {
1232 /* Convert - (~A) to A + 1. */
1248 /* Two's complement FP formats, such as c4x, may overflow. */
1254 {
1263 }
1285 {
1286 /* -(A + B) -> (-B) - A. */
1290 {
1294 }
1296 /* -(A + B) -> (-A) - B. */
1298 {
1302 }
1303 }
1307 /* - (A - B) -> B - A */
1319 /* Fall through. */
1323 {
1332 }
1340 /* In general we can't negate A / B, because if A is INT_MIN and
1341 B is 1, we may turn this into INT_MIN / -1 which is undefined
1342 and actually traps on some architectures. But if overflow is
1343 undefined, we can negate, because - (INT_MIN / 1) is an
1344 overflow. */
1346 {
1351 {
1358 }
1361 {
1368 }
1369 }
1373 /* Convert -((double)float) into (double)(-float). */
1375 {
1379 }
1383 /* Negate -f(x) as f(-x). */
1386 {
1392 }
1396 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1398 {
1403 {
1410 }
1411 }
1416 }
1419 }
1421 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1422 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1423 return NULL_TREE. */
1425 static tree
1427 {
1440 }
1441 \f
1442 /* Split a tree IN into a constant, literal and variable parts that could be
1443 combined with CODE to make IN. "constant" means an expression with
1444 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1445 commutative arithmetic operation. Store the constant part into *CONP,
1446 the literal in *LITP and return the variable part. If a part isn't
1447 present, set it to null. If the tree does not decompose in this way,
1448 return the entire tree as the variable part and the other parts as null.
1450 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1451 case, we negate an operand that was subtracted. Except if it is a
1452 literal for which we use *MINUS_LITP instead.
1454 If NEGATE_P is true, we are negating all of IN, again except a literal
1455 for which we use *MINUS_LITP instead.
1457 If IN is itself a literal or constant, return it as appropriate.
1459 Note that we do not guarantee that any of the three values will be the
1460 same type as IN, but they will have the same signedness and mode. */
1462 static tree
1465 {
1472 /* Strip any conversions that don't change the machine mode or signedness. */
1479 /* We can associate addition and subtraction together (even
1480 though the C standard doesn't say so) for integers because
1481 the value is not affected. For reals, the value might be
1482 affected, so we can't. */
1485 {
1491 /* First see if either of the operands is a literal, then a constant. */
1502 /* If we haven't dealt with either operand, this is not a case we can
1503 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1508 else
1511 /* Now do any needed negations. */
1518 }
1521 else
1525 {
1532 }
1535 }
1537 /* Re-associate trees split by the above function. T1 and T2 are either
1538 expressions to associate or null. Return the new expression, if any. If
1539 we build an operation, do it in TYPE and with CODE. */
1541 static tree
1543 {
1549 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1550 try to fold this since we will have infinite recursion. But do
1551 deal with any NEGATE_EXPRs. */
1554 {
1556 {
1565 }
1567 {
1570 }
1574 }
1578 }
1579 \f
1580 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1581 for use in int_const_binop, size_binop and size_diffop. */
1583 static bool
1585 {
1592 {
1601 }
1606 }
1609 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1610 to produce a new constant. Return NULL_TREE if we don't know how
1611 to evaluate CODE at compile-time.
1613 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1615 tree
1617 {
1621 HOST_WIDE_INT hi;
1623 HOST_WIDE_INT garbageh;
1624 tree t;
1627 int is_sizetype
1637 {
1653 /* It's unclear from the C standard whether shifts can overflow.
1654 The following code ignores overflow; perhaps a C standard
1655 interpretation ruling is needed. */
1684 /* This is a shortcut for a common special case. */
1689 {
1695 }
1697 /* ... fall through ... */
1703 {
1706 }
1709 {
1712 }
1719 /* This is a shortcut for a common special case. */
1724 {
1729 }
1731 /* ... fall through ... */
1749 else
1755 else
1761 }
1764 {
1767 /* Propagate overflow flags ourselves. */
1770 {
1773 }
1774 }
1775 else
1781 }
1783 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1784 constant. We assume ARG1 and ARG2 have the same data type, or at least
1785 are the same kind of constant and the same machine mode. Return zero if
1786 combining the constants is not allowed in the current operating mode.
1788 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1790 static tree
1792 {
1793 /* Sanity check for the recursive cases. */
1804 {
1806 REAL_VALUE_TYPE d1;
1807 REAL_VALUE_TYPE d2;
1808 REAL_VALUE_TYPE value;
1809 REAL_VALUE_TYPE result;
1813 /* The following codes are handled by real_arithmetic. */
1815 {
1826 }
1834 /* Don't perform operation if we honor signaling NaNs and
1835 either operand is a NaN. */
1840 /* Don't perform operation if it would raise a division
1841 by zero exception. */
1847 /* If either operand is a NaN, just return it. Otherwise, set up
1848 for floating-point trap; we return an overflow. */
1857 /* Don't constant fold this floating point operation if
1858 the result has overflowed and flag_trapping_math. */
1866 /* Don't constant fold this floating point operation if the
1867 result may dependent upon the run-time rounding mode and
1868 flag_rounding_math is set, or if GCC's software emulation
1869 is unable to accurately represent the result. */
1880 }
1883 {
1892 {
1903 notrunc);
1907 notrunc);
1911 {
1912 tree magsquared
1916 notrunc);
1917 tree t1
1921 notrunc);
1922 tree t2
1926 notrunc);
1933 }
1938 }
1942 }
1945 }
1947 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1948 indicates which particular sizetype to create. */
1950 tree
1952 {
1954 }
1955 \f
1956 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1957 is a tree code. The type of the result is taken from the operands.
1958 Both must be equivalent integer types, ala int_binop_types_match_p.
1959 If the operands are constant, so is the result. */
1961 tree
1963 {
1972 /* Handle the special case of two integer constants faster. */
1974 {
1975 /* And some specific cases even faster than that. */
1977 {
1982 }
1984 {
1987 }
1989 {
1992 }
1994 /* Handle general case of two integer constants. */
1996 }
1999 }
2001 /* Given two values, either both of sizetype or both of bitsizetype,
2002 compute the difference between the two values. Return the value
2003 in signed type corresponding to the type of the operands. */
2005 tree
2007 {
2009 tree ctype;
2014 /* If the type is already signed, just do the simple thing. */
2022 else
2025 /* If either operand is not a constant, do the conversions to the signed
2026 type and subtract. The hardware will do the right thing with any
2027 overflow in the subtraction. */
2032 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2033 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2034 overflow) and negate (which can't either). Special-case a result
2035 of zero while we're here. */
2040 else
2044 }
2045 \f
2046 /* A subroutine of fold_convert_const handling conversions of an
2047 INTEGER_CST to another integer type. */
2049 static tree
2051 {
2052 tree t;
2054 /* Given an integer constant, make new constant with new type,
2055 appropriately sign-extended or truncated. */
2058 /* Don't set the overflow when
2059 converting a pointer */
2067 }
2069 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2070 to an integer type. */
2072 static tree
2074 {
2076 tree t;
2078 /* The following code implements the floating point to integer
2079 conversion rules required by the Java Language Specification,
2080 that IEEE NaNs are mapped to zero and values that overflow
2081 the target precision saturate, i.e. values greater than
2082 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2083 are mapped to INT_MIN. These semantics are allowed by the
2084 C and C++ standards that simply state that the behavior of
2085 FP-to-integer conversion is unspecified upon overflow. */
2088 REAL_VALUE_TYPE r;
2092 {
2099 }
2101 /* If R is NaN, return zero and show we have an overflow. */
2103 {
2107 }
2109 /* See if R is less than the lower bound or greater than the
2110 upper bound. */
2113 {
2117 {
2121 }
2122 }
2125 {
2128 {
2131 {
2135 }
2136 }
2137 }
2145 }
2147 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2148 to another floating point type. */
2150 static tree
2152 {
2153 REAL_VALUE_TYPE value;
2154 tree t;
2161 }
2163 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2164 type TYPE. If no simplification can be done return NULL_TREE. */
2166 static tree
2168 {
2173 {
2178 }
2180 {
2185 }
2187 }
2189 /* Construct a vector of zero elements of vector type TYPE. */
2191 static tree
2193 {
2204 }
2206 /* Convert expression ARG to type TYPE. Used by the middle-end for
2207 simple conversions in preference to calling the front-end's convert. */
2209 tree
2211 {
2213 tree tem;
2229 {
2234 {
2238 }
2243 {
2246 }
2253 {
2257 }
2259 {
2263 }
2266 {
2281 }
2285 {
2294 {
2298 {
2302 }
2310 }
2314 }
2332 }
2333 }
2334 \f
2335 /* Return false if expr can be assumed not to be an lvalue, true
2336 otherwise. */
2338 static bool
2340 {
2341 /* We only need to wrap lvalue tree codes. */
2343 {
2378 /* Assume the worst for front-end tree codes. */
2382 }
2385 }
2387 /* Return an expr equal to X but certainly not valid as an lvalue. */
2389 tree
2391 {
2392 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2393 us. */
2400 }
2402 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2403 Zero means allow extended lvalues. */
2407 /* When pedantic, return an expr equal to X but certainly not valid as a
2408 pedantic lvalue. Otherwise, return X. */
2410 static tree
2412 {
2415 else
2417 }
2418 \f
2419 /* Given a tree comparison code, return the code that is the logical inverse
2420 of the given code. It is not safe to do this for floating-point
2421 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2422 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2424 enum tree_code
2426 {
2431 {
2462 }
2463 }
2465 /* Similar, but return the comparison that results if the operands are
2466 swapped. This is safe for floating-point. */
2468 enum tree_code
2470 {
2472 {
2498 }
2499 }
2502 /* Convert a comparison tree code from an enum tree_code representation
2503 into a compcode bit-based encoding. This function is the inverse of
2504 compcode_to_comparison. */
2506 static enum comparison_code
2508 {
2510 {
2541 }
2542 }
2544 /* Convert a compcode bit-based encoding of a comparison operator back
2545 to GCC's enum tree_code representation. This function is the
2546 inverse of comparison_to_compcode. */
2548 static enum tree_code
2550 {
2552 {
2583 }
2584 }
2586 /* Return a tree for the comparison which is the combination of
2587 doing the AND or OR (depending on CODE) of the two operations LCODE
2588 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2589 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2590 if this makes the transformation invalid. */
2592 tree
2596 {
2603 {
2614 }
2617 {
2618 /* Eliminate unordered comparisons, as well as LTGT and ORD
2619 which are not used unless the mode has NaNs. */
2625 }
2627 {
2628 /* Check that the original operation and the optimized ones will trap
2629 under the same condition. */
2640 /* In a short-circuited boolean expression the LHS might be
2641 such that the RHS, if evaluated, will never trap. For
2642 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2643 if neither x nor y is NaN. (This is a mixed blessing: for
2644 example, the expression above will never trap, hence
2645 optimizing it to x < y would be invalid). */
2650 /* If the comparison was short-circuited, and only the RHS
2651 trapped, we may now generate a spurious trap. */
2656 /* If we changed the conditions that cause a trap, we lose. */
2659 }
2665 else
2668 }
2670 /* Return nonzero if CODE is a tree code that represents a truth value. */
2672 static int
2674 {
2679 }
2680 \f
2681 /* Return nonzero if two operands (typically of the same tree node)
2682 are necessarily equal. If either argument has side-effects this
2683 function returns zero. FLAGS modifies behavior as follows:
2685 If OEP_ONLY_CONST is set, only return nonzero for constants.
2686 This function tests whether the operands are indistinguishable;
2687 it does not test whether they are equal using C's == operation.
2688 The distinction is important for IEEE floating point, because
2689 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2690 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2692 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2693 even though it may hold multiple values during a function.
2694 This is because a GCC tree node guarantees that nothing else is
2695 executed between the evaluation of its "operands" (which may often
2696 be evaluated in arbitrary order). Hence if the operands themselves
2697 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2698 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2699 unset means assuming isochronic (or instantaneous) tree equivalence.
2700 Unless comparing arbitrary expression trees, such as from different
2701 statements, this flag can usually be left unset.
2703 If OEP_PURE_SAME is set, then pure functions with identical arguments
2704 are considered the same. It is used when the caller has other ways
2705 to ensure that global memory is unchanged in between. */
2707 int
2709 {
2710 /* If either is ERROR_MARK, they aren't equal. */
2714 /* If both types don't have the same signedness, then we can't consider
2715 them equal. We must check this before the STRIP_NOPS calls
2716 because they may change the signedness of the arguments. */
2720 /* If both types don't have the same precision, then it is not safe
2721 to strip NOPs. */
2728 /* In case both args are comparisons but with different comparison
2729 code, try to swap the comparison operands of one arg to produce
2730 a match and compare that variant. */
2734 {
2742 }
2745 /* This is needed for conversions and for COMPONENT_REF.
2746 Might as well play it safe and always test this. */
2752 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2753 We don't care about side effects in that case because the SAVE_EXPR
2754 takes care of that for us. In all other cases, two expressions are
2755 equal if they have no side effects. If we have two identical
2756 expressions with side effects that should be treated the same due
2757 to the only side effects being identical SAVE_EXPR's, that will
2758 be detected in the recursive calls below. */
2764 /* Next handle constant cases, those for which we can return 1 even
2765 if ONLY_CONST is set. */
2768 {
2779 {
2780 /* If we do not distinguish between signed and unsigned zero,
2781 consider them equal. */
2784 }
2788 {
2794 {
2796 flags))
2800 }
2803 }
2807 flags)
2809 flags));
2822 }
2827 /* Define macros to test an operand from arg0 and arg1 for equality and a
2828 variant that allows null and views null as being different from any
2829 non-null value. In the latter case, if either is null, the both
2830 must be; otherwise, do the normal comparison. */
2831 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2832 TREE_OPERAND (arg1, N), flags)
2834 #define OP_SAME_WITH_NULL(N) \
2835 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2836 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2839 {
2841 /* Two conversions are equal only if signedness and modes match. */
2843 {
2853 }
2863 /* For commutative ops, allow the other order. */
2871 /* If either of the pointer (or reference) expressions we are
2872 dereferencing contain a side effect, these cannot be equal. */
2878 {
2888 /* Operands 2 and 3 may be null. */
2895 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2896 may be NULL when we're called to compare MEM_EXPRs. */
2906 }
2910 {
2925 /* Otherwise take into account this is a commutative operation. */
2933 }
2937 {
2939 /* If the CALL_EXPRs call different functions, then they
2940 clearly can not be equal. */
2942 flags))
2945 {
2949 else
2953 }
2955 /* Now see if all the arguments are the same. */
2956 {
2967 /* If we get here and both argument lists are exhausted
2968 then the CALL_EXPRs are equal. */
2970 }
2973 }
2976 /* Consider __builtin_sqrt equal to sqrt. */
2984 }
2986 #undef OP_SAME
2987 #undef OP_SAME_WITH_NULL
2988 }
2989 \f
2990 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2991 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2993 When in doubt, return 0. */
2995 static int
2997 {
3009 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3010 and see if the inner values are the same. This removes any
3011 signedness comparison, which doesn't matter here. */
3018 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3019 actual comparison operand, ARG0.
3021 First throw away any conversions to wider types
3022 already present in the operands. */
3031 {
3034 /* Make sure shorter operand is extended the right way
3035 to match the longer operand. */
3041 }
3044 }
3045 \f
3046 /* See if ARG is an expression that is either a comparison or is performing
3047 arithmetic on comparisons. The comparisons must only be comparing
3048 two different values, which will be stored in *CVAL1 and *CVAL2; if
3049 they are nonzero it means that some operands have already been found.
3050 No variables may be used anywhere else in the expression except in the
3051 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3052 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3054 If this is true, return 1. Otherwise, return zero. */
3056 static int
3058 {
3062 /* We can handle some of the tcc_expression cases here. */
3072 {
3073 /* If we've already found a CVAL1 or CVAL2, this expression is
3074 two complex to handle. */
3080 }
3083 {
3106 /* First see if we can handle the first operand, then the second. For
3107 the second operand, we know *CVAL1 can't be zero. It must be that
3108 one side of the comparison is each of the values; test for the
3109 case where this isn't true by failing if the two operands
3110 are the same. */
3119 ;
3123 ;
3124 else
3128 ;
3132 ;
3133 else
3140 }
3141 }
3142 \f
3143 /* ARG is a tree that is known to contain just arithmetic operations and
3144 comparisons. Evaluate the operations in the tree substituting NEW0 for
3145 any occurrence of OLD0 as an operand of a comparison and likewise for
3146 NEW1 and OLD1. */
3148 static tree
3150 {
3155 /* We can handle some of the tcc_expression cases here. */
3163 {
3178 {
3195 }
3196 /* Fall through - ??? */
3199 {
3203 /* We need to check both for exact equality and tree equality. The
3204 former will be true if the operand has a side-effect. In that
3205 case, we know the operand occurred exactly once. */
3218 }
3222 }
3223 }
3224 \f
3225 /* Return a tree for the case when the result of an expression is RESULT
3226 converted to TYPE and OMITTED was previously an operand of the expression
3227 but is now not needed (e.g., we folded OMITTED * 0).
3229 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3230 the conversion of RESULT to TYPE. */
3232 tree
3234 {
3241 }
3243 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3245 static tree
3247 {
3254 }
3256 /* Return a tree for the case when the result of an expression is RESULT
3257 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3258 of the expression but are now not needed.
3260 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3261 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3262 evaluated before OMITTED2. Otherwise, if neither has side effects,
3263 just do the conversion of RESULT to TYPE. */
3265 tree
3267 {
3276 }
3278 \f
3279 /* Return a simplified tree node for the truth-negation of ARG. This
3280 never alters ARG itself. We assume that ARG is an operation that
3281 returns a truth value (0 or 1).
3283 FIXME: one would think we would fold the result, but it causes
3284 problems with the dominator optimizer. */
3286 tree
3288 {
3292 /* If this is a comparison, we can simply invert it, except for
3293 floating-point non-equality comparisons, in which case we just
3294 enclose a TRUTH_NOT_EXPR around what we have. */
3297 {
3300 && flag_trapping_math
3304 else
3305 {
3310 else
3313 }
3314 }
3317 {
3332 /* Here we can invert either operand. We invert the first operand
3333 unless the second operand is a TRUTH_NOT_EXPR in which case our
3334 result is the XOR of the first operand with the inside of the
3335 negation of the second operand. */
3340 else
3359 {
3362 /* A COND_EXPR may have a throw as one operand, which
3363 then has void type. Just leave void operands
3364 as they are. */
3370 }
3403 }
3406 }
3408 /* Return a simplified tree node for the truth-negation of ARG. This
3409 never alters ARG itself. We assume that ARG is an operation that
3410 returns a truth value (0 or 1).
3412 FIXME: one would think we would fold the result, but it causes
3413 problems with the dominator optimizer. */
3415 tree
3417 {
3418 tree tem;
3428 }
3430 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3431 operands are another bit-wise operation with a common input. If so,
3432 distribute the bit operations to save an operation and possibly two if
3433 constants are involved. For example, convert
3434 (A | B) & (A | C) into A | (B & C)
3435 Further simplification will occur if B and C are constants.
3437 If this optimization cannot be done, 0 will be returned. */
3439 static tree
3441 {
3442 tree common;
3452 {
3456 }
3458 {
3462 }
3464 {
3468 }
3470 {
3474 }
3475 else
3480 }
3482 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3483 with code CODE. This optimization is unsafe. */
3484 static tree
3486 {
3490 /* (A / C) +- (B / C) -> (A +- B) / C. */
3500 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3505 {
3517 }
3520 }
3521 \f
3522 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3523 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3525 static tree
3528 {
3529 tree result;
3532 {
3539 }
3547 }
3549 /* Optimize a bit-field compare.
3551 There are two cases: First is a compare against a constant and the
3552 second is a comparison of two items where the fields are at the same
3553 bit position relative to the start of a chunk (byte, halfword, word)
3554 large enough to contain it. In these cases we can avoid the shift
3555 implicit in bitfield extractions.
3557 For constants, we emit a compare of the shifted constant with the
3558 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3559 compared. For two fields at the same position, we do the ANDs with the
3560 similar mask and compare the result of the ANDs.
3562 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3563 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3564 are the left and right operands of the comparison, respectively.
3566 If the optimization described above can be done, we return the resulting
3567 tree. Otherwise we return zero. */
3569 static tree
3572 {
3581 tree mask;
3582 tree offset;
3584 /* Get all the information about the extractions being done. If the bit size
3585 if the same as the size of the underlying object, we aren't doing an
3586 extraction at all and so can do nothing. We also don't want to
3587 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3588 then will no longer be able to replace it. */
3596 {
3597 /* If this is not a constant, we can only do something if bit positions,
3598 sizes, and signedness are the same. */
3606 }
3608 /* See if we can find a mode to refer to this field. We should be able to,
3609 but fail if we can't. */
3618 /* Set signed and unsigned types of the precision of this mode for the
3619 shifts below. */
3623 /* Compute the bit position and size for the new reference and our offset
3624 within it. If the new reference is the same size as the original, we
3625 won't optimize anything, so return zero. */
3635 /* Make the mask to be used against the extracted field. */
3642 /* If not comparing with constant, just rework the comparison
3643 and return. */
3647 unsigned_type,
3650 mask),
3653 unsigned_type,
3656 mask));
3658 /* Otherwise, we are handling the constant case. See if the constant is too
3659 big for the field. Warn and return a tree of for 0 (false) if so. We do
3660 this not only for its own sake, but to avoid having to test for this
3661 error case below. If we didn't, we might generate wrong code.
3663 For unsigned fields, the constant shifted right by the field length should
3664 be all zero. For signed fields, the high-order bits should agree with
3665 the sign bit. */
3668 {
3672 {
3676 }
3677 }
3678 else
3679 {
3683 {
3687 }
3688 }
3690 /* Single-bit compares should always be against zero. */
3692 {
3695 }
3697 /* Make a new bitfield reference, shift the constant over the
3698 appropriate number of bits and mask it with the computed mask
3699 (in case this was a signed field). If we changed it, make a new one. */
3702 {
3705 }
3715 rhs);
3716 }
3717 \f
3718 /* Subroutine for fold_truthop: decode a field reference.
3720 If EXP is a comparison reference, we return the innermost reference.
3722 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3723 set to the starting bit number.
3725 If the innermost field can be completely contained in a mode-sized
3726 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3728 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3729 otherwise it is not changed.
3731 *PUNSIGNEDP is set to the signedness of the field.
3733 *PMASK is set to the mask used. This is either contained in a
3734 BIT_AND_EXPR or derived from the width of the field.
3736 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3738 Return 0 if this is not a component reference or is one that we can't
3739 do anything with. */
3741 static tree
3746 {
3750 tree unsigned_type;
3753 /* All the optimizations using this function assume integer fields.
3754 There are problems with FP fields since the type_for_size call
3755 below can fail for, e.g., XFmode. */
3759 /* We are interested in the bare arrangement of bits, so strip everything
3760 that doesn't affect the machine mode. However, record the type of the
3761 outermost expression if it may matter below. */
3769 {
3775 }
3784 /* If the number of bits in the reference is the same as the bitsize of
3785 the outer type, then the outer type gives the signedness. Otherwise
3786 (in case of a small bitfield) the signedness is unchanged. */
3790 /* Compute the mask to access the bitfield. */
3799 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3807 }
3809 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3810 bit positions. */
3812 static int
3814 {
3817 tree tmask;
3821 return
3828 }
3830 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3831 represents the sign bit of EXP's type. If EXP represents a sign
3832 or zero extension, also test VAL against the unextended type.
3833 The return value is the (sub)expression whose sign bit is VAL,
3834 or NULL_TREE otherwise. */
3836 static tree
3838 {
3842 tree t;
3844 /* Tree EXP must have an integral type. */
3849 /* Tree VAL must be an integer constant. */
3856 {
3863 }
3864 else
3865 {
3872 }
3874 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3875 treat VAL as if it were unsigned. */
3880 /* Handle extension from a narrower type. */
3886 }
3888 /* Subroutine for fold_truthop: determine if an operand is simple enough
3889 to be evaluated unconditionally. */
3891 static int
3893 {
3894 /* Strip any conversions that don't change the machine mode. */
3903 /* Don't regard global variables as simple. They may be
3904 allocated in ways unknown to the compiler (shared memory,
3905 #pragma weak, etc). */
3908 /* Loading a static variable is unduly expensive, but global
3909 registers aren't expensive. */
3911 }
3912 \f
3913 /* The following functions are subroutines to fold_range_test and allow it to
3914 try to change a logical combination of comparisons into a range test.
3916 For example, both
3917 X == 2 || X == 3 || X == 4 || X == 5
3918 and
3919 X >= 2 && X <= 5
3920 are converted to
3921 (unsigned) (X - 2) <= 3
3923 We describe each set of comparisons as being either inside or outside
3924 a range, using a variable named like IN_P, and then describe the
3925 range with a lower and upper bound. If one of the bounds is omitted,
3926 it represents either the highest or lowest value of the type.
3928 In the comments below, we represent a range by two numbers in brackets
3929 preceded by a "+" to designate being inside that range, or a "-" to
3930 designate being outside that range, so the condition can be inverted by
3931 flipping the prefix. An omitted bound is represented by a "-". For
3932 example, "- [-, 10]" means being outside the range starting at the lowest
3933 possible value and ending at 10, in other words, being greater than 10.
3934 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3935 always false.
3937 We set up things so that the missing bounds are handled in a consistent
3938 manner so neither a missing bound nor "true" and "false" need to be
3939 handled using a special case. */
3941 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3942 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3943 and UPPER1_P are nonzero if the respective argument is an upper bound
3944 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3945 must be specified for a comparison. ARG1 will be converted to ARG0's
3946 type if both are specified. */
3948 static tree
3951 {
3952 tree tem;
3956 /* If neither arg represents infinity, do the normal operation.
3957 Else, if not a comparison, return infinity. Else handle the special
3958 comparison rules. Note that most of the cases below won't occur, but
3959 are handled for consistency. */
3962 {
3967 }
3972 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3973 for neither. In real maths, we cannot assume open ended ranges are
3974 the same. But, this is computer arithmetic, where numbers are finite.
3975 We can therefore make the transformation of any unbounded range with
3976 the value Z, Z being greater than any representable number. This permits
3977 us to treat unbounded ranges as equal. */
3981 {
4002 }
4005 }
4006 \f
4007 /* Given EXP, a logical expression, set the range it is testing into
4008 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4009 actually being tested. *PLOW and *PHIGH will be made of the same
4010 type as the returned expression. If EXP is not a comparison, we
4011 will most likely not be returning a useful value and range. Set
4012 *STRICT_OVERFLOW_P to true if the return value is only valid
4013 because signed overflow is undefined; otherwise, do not change
4014 *STRICT_OVERFLOW_P. */
4016 static tree
4019 {
4026 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4027 and see if we can refine the range. Some of the cases below may not
4028 happen, but it doesn't seem worth worrying about this. We "continue"
4029 the outer loop when we've changed something; otherwise we "break"
4030 the switch, which will "break" the while. */
4036 {
4041 {
4053 }
4056 {
4063 /* We can only do something if the range is testing for zero
4064 and if the second operand is an integer constant. Note that
4065 saying something is "in" the range we make is done by
4066 complementing IN_P since it will set in the initial case of
4067 being not equal to zero; "out" is leaving it alone. */
4074 {
4095 }
4097 /* If this is an unsigned comparison, we also know that EXP is
4098 greater than or equal to zero. We base the range tests we make
4099 on that fact, so we record it here so we can parse existing
4100 range tests. We test arg0_type since often the return type
4101 of, e.g. EQ_EXPR, is boolean. */
4103 {
4107 NULL_TREE))
4112 /* If the high bound is missing, but we have a nonzero low
4113 bound, reverse the range so it goes from zero to the low bound
4114 minus 1. */
4116 {
4121 }
4122 }
4128 /* (-x) IN [a,b] -> x in [-b, -a] */
4140 /* ~ X -> -X - 1 */
4149 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4150 move a constant to the other side. */
4155 /* If EXP is signed, any overflow in the computation is undefined,
4156 so we don't worry about it so long as our computations on
4157 the bounds don't overflow. For unsigned, overflow is defined
4158 and this is exactly the right thing. */
4170 /* Check for an unsigned range which has wrapped around the maximum
4171 value thus making n_high < n_low, and normalize it. */
4173 {
4179 /* If the range is of the form +/- [ x+1, x ], we won't
4180 be able to normalize it. But then, it represents the
4181 whole range or the empty set, so make it
4182 +/- [ -, - ]. */
4186 else
4188 }
4189 else
4213 /* If we're converting arg0 from an unsigned type, to exp,
4214 a signed type, we will be doing the comparison as unsigned.
4215 The tests above have already verified that LOW and HIGH
4216 are both positive.
4218 So we have to ensure that we will handle large unsigned
4219 values the same way that the current signed bounds treat
4220 negative values. */
4223 {
4224 tree high_positive;
4228 /* A range without an upper bound is, naturally, unbounded.
4229 Since convert would have cropped a very large value, use
4230 the max value for the destination type. */
4231 high_positive
4238 high_positive),
4241 /* If the low bound is specified, "and" the range with the
4242 range for which the original unsigned value will be
4243 positive. */
4245 {
4249 integer_zero_node),
4250 high_positive))
4254 }
4255 else
4256 {
4257 /* Otherwise, "or" the range with the range of the input
4258 that will be interpreted as negative. */
4262 integer_zero_node),
4263 high_positive))
4267 }
4268 }
4276 }
4279 }
4281 /* If EXP is a constant, we can evaluate whether this is true or false. */
4283 {
4290 }
4294 }
4295 \f
4296 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4297 type, TYPE, return an expression to test if EXP is in (or out of, depending
4298 on IN_P) the range. Return 0 if the test couldn't be created. */
4300 static tree
4302 {
4304 tree value;
4306 #ifdef HAVE_canonicalize_funcptr_for_compare
4307 /* Disable this optimization for function pointer expressions
4308 on targets that require function pointer canonicalization. */
4313 #endif
4316 {
4322 }
4340 {
4342 {
4346 }
4348 }
4350 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4352 {
4354 HOST_WIDE_INT hi;
4359 {
4362 }
4363 else
4364 {
4367 }
4370 {
4372 {
4375 }
4378 }
4379 }
4381 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4382 This requires wrap-around arithmetics for the type of the expression. */
4384 {
4386 /* There is no requirement that LOW be within the range of ETYPE
4387 if the latter is a subtype. It must, however, be within the base
4388 type of ETYPE. So be sure we do the subtraction in that type. */
4401 }
4403 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4406 {
4409 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4410 for the type in question, as we rely on this here. */
4420 else
4422 }
4436 }
4437 \f
4438 /* Return the predecessor of VAL in its type, handling the infinite case. */
4440 static tree
4442 {
4448 else
4450 }
4452 /* Return the successor of VAL in its type, handling the infinite case. */
4454 static tree
4456 {
4462 else
4464 }
4466 /* Given two ranges, see if we can merge them into one. Return 1 if we
4467 can, 0 if we can't. Set the output range into the specified parameters. */
4469 static int
4472 {
4476 tree tem;
4486 /* Make range 0 be the range that starts first, or ends last if they
4487 start at the same value. Swap them if it isn't. */
4490 || (lowequal
4493 {
4497 }
4499 /* Now flag two cases, whether the ranges are disjoint or whether the
4500 second range is totally subsumed in the first. Note that the tests
4501 below are simplified by the ones above. */
4507 /* We now have four cases, depending on whether we are including or
4508 excluding the two ranges. */
4510 {
4511 /* If they don't overlap, the result is false. If the second range
4512 is a subset it is the result. Otherwise, the range is from the start
4513 of the second to the end of the first. */
4518 else
4520 }
4523 {
4524 /* If they don't overlap, the result is the first range. If they are
4525 equal, the result is false. If the second range is a subset of the
4526 first, and the ranges begin at the same place, we go from just after
4527 the end of the second range to the end of the first. If the second
4528 range is not a subset of the first, or if it is a subset and both
4529 ranges end at the same place, the range starts at the start of the
4530 first range and ends just before the second range.
4531 Otherwise, we can't describe this as a single range. */
4537 {
4541 }
4543 {
4547 }
4548 else
4550 }
4553 {
4554 /* If they don't overlap, the result is the second range. If the second
4555 is a subset of the first, the result is false. Otherwise,
4556 the range starts just after the first range and ends at the
4557 end of the second. */
4562 else
4563 {
4567 }
4568 }
4570 else
4571 {
4572 /* The case where we are excluding both ranges. Here the complex case
4573 is if they don't overlap. In that case, the only time we have a
4574 range is if they are adjacent. If the second is a subset of the
4575 first, the result is the first. Otherwise, the range to exclude
4576 starts at the beginning of the first range and ends at the end of the
4577 second. */
4579 {
4584 else
4585 {
4586 /* Canonicalize - [min, x] into - [-, x]. */
4589 {
4594 /* FALLTHROUGH */
4607 }
4609 /* Canonicalize - [x, max] into - [x, -]. */
4612 {
4617 /* FALLTHROUGH */
4632 }
4634 /* The ranges might be also adjacent between the maximum and
4635 minimum values of the given type. For
4636 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4637 return + [x + 1, y - 1]. */
4639 {
4646 }
4647 else
4649 }
4650 }
4653 else
4655 }
4659 }
4660 \f
4662 /* Subroutine of fold, looking inside expressions of the form
4663 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4664 of the COND_EXPR. This function is being used also to optimize
4665 A op B ? C : A, by reversing the comparison first.
4667 Return a folded expression whose code is not a COND_EXPR
4668 anymore, or NULL_TREE if no folding opportunity is found. */
4670 static tree
4672 {
4677 tree tem;
4682 /* If we have A op 0 ? A : -A, consider applying the following
4683 transformations:
4685 A == 0? A : -A same as -A
4686 A != 0? A : -A same as A
4687 A >= 0? A : -A same as abs (A)
4688 A > 0? A : -A same as abs (A)
4689 A <= 0? A : -A same as -abs (A)
4690 A < 0? A : -A same as -abs (A)
4692 None of these transformations work for modes with signed
4693 zeros. If A is +/-0, the first two transformations will
4694 change the sign of the result (from +0 to -0, or vice
4695 versa). The last four will fix the sign of the result,
4696 even though the original expressions could be positive or
4697 negative, depending on the sign of A.
4699 Note that all these transformations are correct if A is
4700 NaN, since the two alternatives (A and -A) are also NaNs. */
4706 /* In the case that A is of the form X-Y, '-A' (arg2) may
4707 have already been folded to Y-X, check for that. */
4715 {
4727 /* Fall through. */
4749 }
4751 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4752 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4753 both transformations are correct when A is NaN: A != 0
4754 is then true, and A == 0 is false. */
4757 {
4762 }
4764 /* Try some transformations of A op B ? A : B.
4766 A == B? A : B same as B
4767 A != B? A : B same as A
4768 A >= B? A : B same as max (A, B)
4769 A > B? A : B same as max (B, A)
4770 A <= B? A : B same as min (A, B)
4771 A < B? A : B same as min (B, A)
4773 As above, these transformations don't work in the presence
4774 of signed zeros. For example, if A and B are zeros of
4775 opposite sign, the first two transformations will change
4776 the sign of the result. In the last four, the original
4777 expressions give different results for (A=+0, B=-0) and
4778 (A=-0, B=+0), but the transformed expressions do not.
4780 The first two transformations are correct if either A or B
4781 is a NaN. In the first transformation, the condition will
4782 be false, and B will indeed be chosen. In the case of the
4783 second transformation, the condition A != B will be true,
4784 and A will be chosen.
4786 The conversions to max() and min() are not correct if B is
4787 a number and A is not. The conditions in the original
4788 expressions will be false, so all four give B. The min()
4789 and max() versions would give a NaN instead. */
4791 /* Avoid these transformations if the COND_EXPR may be used
4792 as an lvalue in the C++ front-end. PR c++/19199. */
4793 && (in_gimple_form
4798 {
4803 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4805 {
4809 }
4812 {
4821 /* In C++ a ?: expression can be an lvalue, so put the
4822 operand which will be used if they are equal first
4823 so that we can convert this back to the
4824 corresponding COND_EXPR. */
4826 {
4833 }
4840 {
4847 }
4860 }
4861 }
4863 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4864 we might still be able to simplify this. For example,
4865 if C1 is one less or one more than C2, this might have started
4866 out as a MIN or MAX and been transformed by this function.
4867 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4873 {
4875 /* We can replace A with C1 in this case. */
4880 /* If C1 is C2 + 1, this is min(A, C2). */
4882 OEP_ONLY_CONST)
4886 OEP_ONLY_CONST))
4892 /* If C1 is C2 - 1, this is min(A, C2). */
4894 OEP_ONLY_CONST)
4898 OEP_ONLY_CONST))
4904 /* If C1 is C2 - 1, this is max(A, C2). */
4906 OEP_ONLY_CONST)
4910 OEP_ONLY_CONST))
4916 /* If C1 is C2 + 1, this is max(A, C2). */
4918 OEP_ONLY_CONST)
4922 OEP_ONLY_CONST))
4930 }
4933 }
4936 \f
4937 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4938 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4939 #endif
4941 /* EXP is some logical combination of boolean tests. See if we can
4942 merge it into some range test. Return the new tree if so. */
4944 static tree
4946 {
4954 tree tem;
4958 /* If this is an OR operation, invert both sides; we will invert
4959 again at the end. */
4963 /* If both expressions are the same, if we can merge the ranges, and we
4964 can build the range test, return it or it inverted. If one of the
4965 ranges is always true or always false, consider it to be the same
4966 expression as the other. */
4974 {
4978 }
4980 /* On machines where the branch cost is expensive, if this is a
4981 short-circuited branch and the underlying object on both sides
4982 is the same, make a non-short-circuit operation. */
4988 {
4989 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4990 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4991 which cases we can't do this. */
4999 {
5008 {
5011 WARN_STRICT_OVERFLOW_COMPARISON);
5015 }
5016 }
5017 }
5020 }
5021 \f
5022 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5023 bit value. Arrange things so the extra bits will be set to zero if and
5024 only if C is signed-extended to its full width. If MASK is nonzero,
5025 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5027 static tree
5029 {
5032 tree temp;
5037 /* We work by getting just the sign bit into the low-order bit, then
5038 into the high-order bit, then sign-extend. We then XOR that value
5039 with C. */
5043 /* We must use a signed type in order to get an arithmetic right shift.
5044 However, we must also avoid introducing accidental overflows, so that
5045 a subsequent call to integer_zerop will work. Hence we must
5046 do the type conversion here. At this point, the constant is either
5047 zero or one, and the conversion to a signed type can never overflow.
5048 We could get an overflow if this conversion is done anywhere else. */
5057 /* If necessary, convert the type back to match the type of C. */
5062 }
5063 \f
5064 /* Find ways of folding logical expressions of LHS and RHS:
5065 Try to merge two comparisons to the same innermost item.
5066 Look for range tests like "ch >= '0' && ch <= '9'".
5067 Look for combinations of simple terms on machines with expensive branches
5068 and evaluate the RHS unconditionally.
5070 For example, if we have p->a == 2 && p->b == 4 and we can make an
5071 object large enough to span both A and B, we can do this with a comparison
5072 against the object ANDed with the a mask.
5074 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5075 operations to do this with one comparison.
5077 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5078 function and the one above.
5080 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5081 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5083 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5084 two operands.
5086 We return the simplified tree or 0 if no optimization is possible. */
5088 static tree
5090 {
5091 /* If this is the "or" of two comparisons, we can do something if
5092 the comparisons are NE_EXPR. If this is the "and", we can do something
5093 if the comparisons are EQ_EXPR. I.e.,
5094 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5096 WANTED_CODE is this operation code. For single bit fields, we can
5097 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5098 comparison for one-bit fields. */
5120 /* Start by getting the comparison codes. Fail if anything is volatile.
5121 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5122 it were surrounded with a NE_EXPR. */
5131 {
5135 }
5138 {
5142 }
5153 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5156 {
5157 tree result;
5160 {
5165 }
5168 {
5174 }
5175 }
5180 /* If the RHS can be evaluated unconditionally and its operands are
5181 simple, it wins to evaluate the RHS unconditionally on machines
5182 with expensive branches. In this case, this isn't a comparison
5183 that can be merged. Avoid doing this if the RHS is a floating-point
5184 comparison since those can trap. */
5190 {
5191 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5201 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5212 {
5216 }
5217 }
5219 /* See if the comparisons can be merged. Then get all the parameters for
5220 each side. */
5244 /* It must be true that the inner operation on the lhs of each
5245 comparison must be the same if we are to be able to do anything.
5246 Then see if we have constants. If not, the same must be true for
5247 the rhs's. */
5258 else
5261 /* If either comparison code is not correct for our logical operation,
5262 fail. However, we can convert a one-bit comparison against zero into
5263 the opposite comparison against that bit being set in the field. */
5267 {
5269 {
5270 /* Make the left operand unsigned, since we are only interested
5271 in the value of one bit. Otherwise we are doing the wrong
5272 thing below. */
5275 }
5276 else
5278 }
5280 /* This is analogous to the code for l_const above. */
5282 {
5284 {
5287 }
5288 else
5290 }
5292 /* See if we can find a mode that contains both fields being compared on
5293 the left. If we can't, fail. Otherwise, update all constants and masks
5294 to be relative to a field of that size. */
5299 volatilep);
5309 {
5312 }
5320 {
5328 {
5332 }
5333 }
5335 {
5343 {
5347 }
5348 }
5350 /* If the right sides are not constant, do the same for it. Also,
5351 disallow this optimization if a size or signedness mismatch occurs
5352 between the left and right sides. */
5354 {
5357 /* Make sure the two fields on the right
5358 correspond to the left without being swapped. */
5366 volatilep);
5376 {
5379 }
5386 /* Make a mask that corresponds to both fields being compared.
5387 Do this for both items being compared. If the operands are the
5388 same size and the bits being compared are in the same position
5389 then we can do this by masking both and comparing the masked
5390 results. */
5394 {
5406 }
5408 /* There is still another way we can do something: If both pairs of
5409 fields being compared are adjacent, we may be able to make a wider
5410 field containing them both.
5412 Note that we still must mask the lhs/rhs expressions. Furthermore,
5413 the mask must be shifted to account for the shift done by
5414 make_bit_field_ref. */
5419 {
5420 tree type;
5432 /* Convert to the smaller type before masking out unwanted bits. */
5435 {
5437 {
5441 }
5443 {
5447 }
5448 }
5457 }
5460 }
5462 /* Handle the case of comparisons with constants. If there is something in
5463 common between the masks, those bits of the constants must be the same.
5464 If not, the condition is always false. Test for this to avoid generating
5465 incorrect code below. */
5470 {
5472 {
5475 }
5476 else
5477 {
5480 }
5481 }
5483 /* Construct the expression we will return. First get the component
5484 reference we will make. Unless the mask is all ones the width of
5485 that field, perform the mask operation. Then compare with the
5486 merged constant. */
5496 }
5497 \f
5498 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5499 constant. */
5501 static tree
5503 {
5507 tree minmax_const;
5509 tree inner;
5519 /* If something does not permit us to optimize, return the original tree. */
5527 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5528 and GT_EXPR, doing the rest with recursive calls using logical
5529 simplifications. */
5531 {
5533 {
5539 }
5542 return
5544 optimize_minmax_comparison
5546 optimize_minmax_comparison
5551 /* MAX (X, 0) == 0 -> X <= 0 */
5555 /* MAX (X, 0) == 5 -> X == 5 */
5559 /* MAX (X, 0) == -1 -> false */
5563 /* MIN (X, 0) == 0 -> X >= 0 */
5567 /* MIN (X, 0) == 5 -> false */
5570 else
5571 /* MIN (X, 0) == -1 -> X == -1 */
5576 /* MAX (X, 0) > 0 -> X > 0
5577 MAX (X, 0) > 5 -> X > 5 */
5581 /* MAX (X, 0) > -1 -> true */
5585 /* MIN (X, 0) > 0 -> false
5586 MIN (X, 0) > 5 -> false */
5589 else
5590 /* MIN (X, 0) > -1 -> X > -1 */
5595 }
5596 }
5597 \f
5598 /* T is an integer expression that is being multiplied, divided, or taken a
5599 modulus (CODE says which and what kind of divide or modulus) by a
5600 constant C. See if we can eliminate that operation by folding it with
5601 other operations already in T. WIDE_TYPE, if non-null, is a type that
5602 should be used for the computation if wider than our type.
5604 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5605 (X * 2) + (Y * 4). We must, however, be assured that either the original
5606 expression would not overflow or that overflow is undefined for the type
5607 in the language in question.
5609 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5610 the machine has a multiply-accumulate insn or that this is part of an
5611 addressing calculation.
5613 If we return a non-null expression, it is an equivalent form of the
5614 original computation, but need not be in the original type.
5616 We set *STRICT_OVERFLOW_P to true if the return values depends on
5617 signed overflow being undefined. Otherwise we do not change
5618 *STRICT_OVERFLOW_P. */
5620 static tree
5623 {
5624 /* To avoid exponential search depth, refuse to allow recursion past
5625 three levels. Beyond that (1) it's highly unlikely that we'll find
5626 something interesting and (2) we've probably processed it before
5627 when we built the inner expression. */
5630 tree ret;
5635 depth++;
5637 depth--;
5640 }
5642 static tree
5645 {
5656 /* Don't deal with constants of zero here; they confuse the code below. */
5666 /* Note that we need not handle conditional operations here since fold
5667 already handles those cases. So just do arithmetic here. */
5669 {
5671 /* For a constant, we can always simplify if we are a multiply
5672 or (for divide and modulus) if it is a multiple of our constant. */
5680 /* If op0 is an expression ... */
5686 /* ... and is unsigned, and its type is smaller than ctype,
5687 then we cannot pass through as widening. */
5693 /* ... or this is a truncation (t is narrower than op0),
5694 then we cannot pass through this narrowing. */
5697 /* ... or signedness changes for division or modulus,
5698 then we cannot pass through this conversion. */
5704 /* Pass the constant down and see if we can make a simplification. If
5705 we can, replace this expression with the inner simplification for
5706 possible later conversion to our or some other type. */
5711 code == MULT_EXPR
5713 strict_overflow_p))))
5718 /* If widening the type changes it from signed to unsigned, then we
5719 must avoid building ABS_EXPR itself as unsigned. */
5721 {
5725 {
5728 }
5730 }
5731 /* FALLTHROUGH */
5739 /* If widening the type changes the signedness, then we can't perform
5740 this optimization as that changes the result. */
5744 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5750 {
5757 }
5761 /* If the second operand is constant, this is a multiplication
5762 or floor division, by a power of two, so we can treat it that
5763 way unless the multiplier or divisor overflows. Signed
5764 left-shift overflow is implementation-defined rather than
5765 undefined in C90, so do not convert signed left shift into
5766 multiplication. */
5769 /* const_binop may not detect overflow correctly,
5770 so check for it explicitly here. */
5775 size_one_node,
5785 /* See if we can eliminate the operation on both sides. If we can, we
5786 can return a new PLUS or MINUS. If we can't, the only remaining
5787 cases where we can do anything are if the second operand is a
5788 constant. */
5794 /* If not multiplication, we can only do this if both operands
5795 are divisible by c. */
5798 {
5803 }
5805 /* If this was a subtraction, negate OP1 and set it to be an addition.
5806 This simplifies the logic below. */
5813 /* If either OP1 or C are negative, this optimization is not safe for
5814 some of the division and remainder types while for others we need
5815 to change the code. */
5817 {
5825 }
5827 /* If it's a multiply or a division/modulus operation of a multiple
5828 of our constant, do the operation and verify it doesn't overflow. */
5831 {
5834 /* We allow the constant to overflow with wrapping semantics. */
5838 }
5839 else
5842 /* If we have an unsigned type is not a sizetype, we cannot widen
5843 the operation since it will change the result if the original
5844 computation overflowed. */
5850 /* If we were able to eliminate our operation from the first side,
5851 apply our operation to the second side and reform the PLUS. */
5855 /* The last case is if we are a multiply. In that case, we can
5856 apply the distributive law to commute the multiply and addition
5857 if the multiplication of the constants doesn't overflow. */
5863 op1);
5868 /* We have a special case here if we are doing something like
5869 (C * 8) % 4 since we know that's zero. */
5876 /* ... fall through ... */
5880 /* If we can extract our operation from the LHS, do so and return a
5881 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5882 do something only if the second operand is a constant. */
5896 /* If these are the same operation types, we can associate them
5897 assuming no overflow. */
5904 /* If these operations "cancel" each other, we have the main
5905 optimizations of this pass, which occur when either constant is a
5906 multiple of the other, in which case we replace this with either an
5907 operation or CODE or TCODE.
5909 If we have an unsigned type that is not a sizetype, we cannot do
5910 this since it will change the result if the original computation
5911 overflowed. */
5918 {
5920 {
5927 }
5929 {
5936 }
5937 }
5942 }
5945 }
5946 \f
5947 /* Return a node which has the indicated constant VALUE (either 0 or
5948 1), and is of the indicated TYPE. */
5950 tree
5952 {
5957 else
5959 }
5962 /* Return true if expr looks like an ARRAY_REF and set base and
5963 offset to the appropriate trees. If there is no offset,
5964 offset is set to NULL_TREE. Base will be canonicalized to
5965 something you can get the element type from using
5966 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5967 in bytes to the base. */
5969 static bool
5971 {
5972 /* One canonical form is a PLUS_EXPR with the first
5973 argument being an ADDR_EXPR with a possible NOP_EXPR
5974 attached. */
5976 {
5979 /* Strip NOP_EXPRs here because the C frontends and/or
5980 folders present us (int *)&x.a + 4B possibly. */
5983 {
5987 else
5991 }
5992 }
5993 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5994 which we transform into an ADDR_EXPR with appropriate
5995 offset. For other arguments to the ADDR_EXPR we assume
5996 zero offset and as such do not care about the ADDR_EXPR
5997 type and strip possible nops from it. */
5999 {
6002 {
6007 }
6008 else
6009 {
6010 /* Handle array-to-pointer decay as &a. */
6013 else
6016 }
6018 }
6019 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
6022 {
6026 }
6029 }
6032 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6033 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6034 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6035 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6036 COND is the first argument to CODE; otherwise (as in the example
6037 given here), it is the second argument. TYPE is the type of the
6038 original expression. Return NULL_TREE if no simplification is
6039 possible. */
6041 static tree
6045 {
6052 /* This transformation is only worthwhile if we don't have to wrap
6053 arg in a SAVE_EXPR, and the operation can be simplified on at least
6054 one of the branches once its pushed inside the COND_EXPR. */
6059 {
6063 /* If this operand throws an expression, then it does not make
6064 sense to try to perform a logical or arithmetic operation
6065 involving it. */
6070 }
6071 else
6072 {
6077 }
6081 {
6085 else
6087 }
6089 {
6093 else
6095 }
6099 }
6101 \f
6102 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6104 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6105 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6106 ADDEND is the same as X.
6108 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6109 and finite. The problematic cases are when X is zero, and its mode
6110 has signed zeros. In the case of rounding towards -infinity,
6111 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6112 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6114 static bool
6116 {
6120 /* Don't allow the fold with -fsignaling-nans. */
6124 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6128 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6133 /* The mode has signed zeros, and we have to honor their sign.
6134 In this situation, there is only one case we can return true for.
6135 X - 0 is the same as X unless rounding towards -infinity is
6136 supported. */
6138 }
6140 /* Subroutine of fold() that checks comparisons of built-in math
6141 functions against real constants.
6143 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6144 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6145 is the type of the result and ARG0 and ARG1 are the operands of the
6146 comparison. ARG1 must be a TREE_REAL_CST.
6148 The function returns the constant folded tree if a simplification
6149 can be made, and NULL_TREE otherwise. */
6151 static tree
6154 {
6155 REAL_VALUE_TYPE c;
6158 {
6164 {
6165 /* sqrt(x) < y is always false, if y is negative. */
6169 /* sqrt(x) > y is always true, if y is negative and we
6170 don't care about NaNs, i.e. negative values of x. */
6174 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6177 }
6179 {
6180 REAL_VALUE_TYPE c2;
6186 {
6187 /* sqrt(x) > y is x == +Inf, when y is very large. */
6192 /* sqrt(x) > y is always false, when y is very large
6193 and we don't care about infinities. */
6195 }
6197 /* sqrt(x) > c is the same as x > c*c. */
6200 }
6202 {
6203 REAL_VALUE_TYPE c2;
6209 {
6210 /* sqrt(x) < y is always true, when y is a very large
6211 value and we don't care about NaNs or Infinities. */
6215 /* sqrt(x) < y is x != +Inf when y is very large and we
6216 don't care about NaNs. */
6221 /* sqrt(x) < y is x >= 0 when y is very large and we
6222 don't care about Infinities. */
6227 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6236 dconst0)),
6239 c2)));
6240 }
6242 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6247 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6250 {
6255 dconst0)),
6258 c2)));
6259 }
6260 }
6261 }
6264 }
6266 /* Subroutine of fold() that optimizes comparisons against Infinities,
6267 either +Inf or -Inf.
6269 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6270 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6271 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6273 The function returns the constant folded tree if a simplification
6274 can be made, and NULL_TREE otherwise. */
6276 static tree
6278 {
6280 REAL_VALUE_TYPE max;
6281 tree temp;
6286 /* For negative infinity swap the sense of the comparison. */
6292 {
6294 /* x > +Inf is always false, if with ignore sNANs. */
6300 /* x <= +Inf is always true, if we don't case about NaNs. */
6304 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6307 {
6310 }
6315 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6321 /* x < +Inf is always equal to x <= DBL_MAX. */
6327 /* x != +Inf is always equal to !(x > DBL_MAX). */
6339 }
6342 }
6344 /* Subroutine of fold() that optimizes comparisons of a division by
6345 a nonzero integer constant against an integer constant, i.e.
6346 X/C1 op C2.
6348 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6349 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6350 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6352 The function returns the constant folded tree if a simplification
6353 can be made, and NULL_TREE otherwise. */
6355 static tree
6357 {
6362 HOST_WIDE_INT hpart;
6367 /* We have to do this the hard way to detect unsigned overflow.
6368 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6379 {
6384 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6392 }
6394 {
6398 {
6417 }
6418 }
6419 else
6420 {
6421 /* A negative divisor reverses the relational operators. */
6427 {
6446 }
6447 }
6450 {
6471 {
6474 }
6479 {
6482 }
6487 {
6490 }
6495 {
6498 }
6503 }
6506 }
6509 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6510 equality/inequality test, then return a simplified form of the test
6511 using a sign testing. Otherwise return NULL. TYPE is the desired
6512 result type. */
6514 static tree
6516 tree result_type)
6517 {
6518 /* If this is testing a single bit, we can optimize the test. */
6522 {
6523 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6524 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6528 /* This is only a win if casting to a signed type is cheap,
6529 i.e. when arg00's type is not a partial mode. */
6532 {
6537 }
6538 }
6541 }
6543 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6544 equality/inequality test, then return a simplified form of
6545 the test using shifts and logical operations. Otherwise return
6546 NULL. TYPE is the desired result type. */
6548 tree
6550 tree result_type)
6551 {
6552 /* If this is testing a single bit, we can optimize the test. */
6556 {
6565 /* First, see if we can fold the single bit test into a sign-bit
6566 test. */
6568 result_type);
6572 /* Otherwise we have (A & C) != 0 where C is a single bit,
6573 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6574 Similarly for (A & C) == 0. */
6576 /* If INNER is a right shift of a constant and it plus BITNUM does
6577 not overflow, adjust BITNUM and INNER. */
6584 {
6587 }
6589 /* If we are going to be able to omit the AND below, we must do our
6590 operations as unsigned. If we must use the AND, we have a choice.
6591 Normally unsigned is faster, but for some machines signed is. */
6592 #ifdef LOAD_EXTEND_OP
6595 #else
6597 #endif
6613 /* Put the AND last so it can combine with more things. */
6616 /* Make sure to return the proper type. */
6620 }
6622 }
6624 /* Check whether we are allowed to reorder operands arg0 and arg1,
6625 such that the evaluation of arg1 occurs before arg0. */
6627 static bool
6629 {
6636 }
6638 /* Test whether it is preferable two swap two operands, ARG0 and
6639 ARG1, for example because ARG0 is an integer constant and ARG1
6640 isn't. If REORDER is true, only recommend swapping if we can
6641 evaluate the operands in reverse order. */
6643 bool
6645 {
6676 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6677 for commutative and comparison operators. Ensuring a canonical
6678 form allows the optimizers to find additional redundancies without
6679 having to explicitly check for both orderings. */
6685 /* Put SSA_NAMEs last. */
6691 /* Put variables last. */
6698 }
6700 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6701 ARG0 is extended to a wider type. */
6703 static tree
6705 {
6707 tree arg1_unw;
6716 #ifdef HAVE_canonicalize_funcptr_for_compare
6717 /* Disable this optimization if we're casting a function pointer
6718 type on targets that require function pointer canonicalization. */
6723 #endif
6730 /* If possible, express the comparison in the shorter mode. */
6746 /* If we are comparing with the integer that does not fit into the range
6747 of the shorter type, the result is known. */
6758 {
6785 }
6788 }
6790 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6791 ARG0 just the signedness is changed. */
6793 static tree
6796 {
6797 tree arg0_inner;
6808 #ifdef HAVE_canonicalize_funcptr_for_compare
6809 /* Disable this optimization if we're casting a function pointer
6810 type on targets that require function pointer canonicalization. */
6815 #endif
6835 else
6839 }
6841 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6842 step of the array. Reconstructs s and delta in the case of s * delta
6843 being an integer constant (and thus already folded).
6844 ADDR is the address. MULT is the multiplicative expression.
6845 If the function succeeds, the new address expression is returned. Otherwise
6846 NULL_TREE is returned. */
6848 static tree
6850 {
6854 tree itype;
6857 /* Canonicalize op1 into a possibly non-constant delta
6858 and an INTEGER_CST s. */
6860 {
6867 {
6870 }
6872 {
6875 }
6876 else
6878 }
6880 {
6883 }
6884 else
6885 {
6886 /* Simulate we are delta * 1. */
6889 }
6892 {
6894 {
6895 /* Remember if this was a multi-dimensional array. */
6908 {
6911 }
6912 else
6913 {
6914 /* Try if delta is a multiple of step. */
6919 }
6921 /* Only fold here if we can verify we do not overflow one
6922 dimension of a multi-dimensional array. */
6924 {
6925 tree tmp;
6941 }
6944 }
6945 else
6950 }
6952 /* We found the suitable array reference. So copy everything up to it,
6953 and replace the index. */
6960 {
6964 }
6972 }
6975 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6976 means A >= Y && A != MAX, but in this case we know that
6977 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6979 static tree
6981 {
6988 else
6997 {
7000 }
7002 {
7005 }
7006 else
7017 }
7019 /* Fold a sum or difference of at least one multiplication.
7020 Returns the folded tree or NULL if no simplification could be made. */
7022 static tree
7024 {
7028 /* (A * C) +- (B * C) -> (A+-B) * C.
7029 (A * C) +- A -> A * (C+-1).
7030 We are most concerned about the case where C is a constant,
7031 but other combinations show up during loop reduction. Since
7032 it is not difficult, try all four possibilities. */
7035 {
7038 }
7039 else
7040 {
7043 }
7045 {
7048 }
7049 else
7050 {
7053 }
7065 /* No identical multiplicands; see if we can find a common
7066 power-of-two factor in non-power-of-two multiplies. This
7067 can help in multi-dimensional array access. */
7070 {
7073 tree maybe_same;
7077 /* Move min of absolute values to int11. */
7080 {
7085 }
7086 else
7090 {
7098 }
7099 }
7109 }
7111 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7112 specified by EXPR into the buffer PTR of length LEN bytes.
7113 Return the number of bytes placed in the buffer, or zero
7114 upon failure. */
7116 static int
7118 {
7129 {
7133 else
7138 {
7145 else
7147 }
7148 else
7151 }
7153 }
7156 /* Subroutine of native_encode_expr. Encode the REAL_CST
7157 specified by EXPR into the buffer PTR of length LEN bytes.
7158 Return the number of bytes placed in the buffer, or zero
7159 upon failure. */
7161 static int
7163 {
7169 /* There are always 32 bits in each long, no matter the size of
7170 the hosts long. We handle floating point representations with
7171 up to 192 bits. */
7181 {
7186 {
7193 else
7195 }
7196 else
7199 }
7201 }
7203 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7204 specified by EXPR into the buffer PTR of length LEN bytes.
7205 Return the number of bytes placed in the buffer, or zero
7206 upon failure. */
7208 static int
7210 {
7212 tree part;
7223 }
7226 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7227 specified by EXPR into the buffer PTR of length LEN bytes.
7228 Return the number of bytes placed in the buffer, or zero
7229 upon failure. */
7231 static int
7233 {
7243 {
7245 {
7248 }
7249 else
7253 {
7256 }
7257 else
7258 {
7262 }
7264 }
7266 }
7269 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7270 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7271 buffer PTR of length LEN bytes. Return the number of bytes
7272 placed in the buffer, or zero upon failure. */
7274 static int
7276 {
7278 {
7293 }
7294 }
7297 /* Subroutine of native_interpret_expr. Interpret the contents of
7298 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7299 If the buffer cannot be interpreted, return NULL_TREE. */
7301 static tree
7303 {
7317 {
7320 {
7327 else
7329 }
7330 else
7336 else
7339 }
7342 }
7345 /* Subroutine of native_interpret_expr. Interpret the contents of
7346 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7347 If the buffer cannot be interpreted, return NULL_TREE. */
7349 static tree
7351 {
7356 /* There are always 32 bits in each long, no matter the size of
7357 the hosts long. We handle floating point representations with
7358 up to 192 bits. */
7359 REAL_VALUE_TYPE r;
7369 {
7372 {
7379 else
7381 }
7382 else
7387 }
7391 }
7394 /* Subroutine of native_interpret_expr. Interpret the contents of
7395 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7396 If the buffer cannot be interpreted, return NULL_TREE. */
7398 static tree
7400 {
7415 }
7418 /* Subroutine of native_interpret_expr. Interpret the contents of
7419 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7420 If the buffer cannot be interpreted, return NULL_TREE. */
7422 static tree
7424 {
7436 {
7441 }
7443 }
7446 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7447 the buffer PTR of length LEN as a constant of type TYPE. For
7448 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7449 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7450 return NULL_TREE. */
7452 static tree
7454 {
7456 {
7473 }
7474 }
7477 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7478 TYPE at compile-time. If we're unable to perform the conversion
7479 return NULL_TREE. */
7481 static tree
7483 {
7484 /* We support up to 512-bit values (for V8DFmode). */
7488 /* Check that the host and target are sane. */
7497 }
7500 /* Fold a unary expression of code CODE and type TYPE with operand
7501 OP0. Return the folded expression if folding is successful.
7502 Otherwise, return NULL_TREE. */
7504 tree
7506 {
7507 tree tem;
7508 tree arg0;
7516 {
7519 {
7520 /* Don't use STRIP_NOPS, because signedness of argument type
7521 matters. */
7523 }
7524 else
7525 {
7526 /* Strip any conversions that don't change the mode. This
7527 is safe for every expression, except for a comparison
7528 expression because its signedness is derived from its
7529 operands.
7531 Note that this is done as an internal manipulation within
7532 the constant folder, in order to find the simplest
7533 representation of the arguments so that their form can be
7534 studied. In any cases, the appropriate type conversions
7535 should be put back in the tree that will get out of the
7536 constant folder. */
7538 }
7539 }
7542 {
7547 {
7557 /* If this was a conversion, and all we did was to move into
7558 inside the COND_EXPR, bring it back out. But leave it if
7559 it is a conversion from integer to integer and the
7560 result precision is no wider than a word since such a
7561 conversion is cheap and may be optimized away by combine,
7562 while it couldn't if it were outside the COND_EXPR. Then return
7563 so we don't get into an infinite recursion loop taking the
7564 conversion out and then back in. */
7576 && (INTEGRAL_TYPE_P
7588 }
7590 {
7592 {
7596 }
7600 integer_one_node),
7602 integer_zero_node));
7603 }
7604 }
7607 {
7615 /* If we have (type) (a CMP b) and type is an integral type, return
7616 new expression involving the new type. */
7621 /* Handle cases of two conversions in a row. */
7624 {
7646 /* In addition to the cases of two conversions in a row
7647 handled below, if we are converting something to its own
7648 type via an object of identical or wider precision, neither
7649 conversion is needed. */
7656 /* Likewise, if the intermediate and final types are either both
7657 float or both integer, we don't need the middle conversion if
7658 it is wider than the final type and doesn't change the signedness
7659 (for integers). Avoid this if the final type is a pointer
7660 since then we sometimes need the inner conversion. Likewise if
7661 the outer has a precision not equal to the size of its mode. */
7670 && ! final_ptr
7674 /* If we have a sign-extension of a zero-extended value, we can
7675 replace that by a single zero-extension. */
7681 /* Two conversions in a row are not needed unless:
7682 - some conversion is floating-point (overstrict for now), or
7683 - some conversion is a vector (overstrict for now), or
7684 - the intermediate type is narrower than both initial and
7685 final, or
7686 - the intermediate type and innermost type differ in signedness,
7687 and the outermost type is wider than the intermediate, or
7688 - the initial type is a pointer type and the precisions of the
7689 intermediate and final types differ, or
7690 - the final type is a pointer type and the precisions of the
7691 initial and intermediate types differ.
7692 - the final type is a pointer type and the initial type not
7693 - the initial type is a pointer to an array and the final type
7694 not. */
7708 && ! (inside_ptr
7712 }
7714 /* Handle (T *)&A.B.C for A being of type T and B and C
7715 living at offset zero. This occurs frequently in
7716 C++ upcasting and then accessing the base. */
7720 {
7722 tree offset;
7728 /* If the reference was to a (constant) zero offset, we can use
7729 the address of the base if it has the same base type
7730 as the result type. */
7735 }
7740 /* Detect assigning a bitfield. */
7742 && DECL_BIT_FIELD
7744 {
7745 /* Don't leave an assignment inside a conversion
7746 unless assigning a bitfield. */
7748 /* First do the assignment, then return converted constant. */
7753 }
7755 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7756 constants (if x has signed type, the sign bit cannot be set
7757 in c). This folds extension into the BIT_AND_EXPR. */
7762 {
7772 <= HOST_BITS_PER_WIDE_INT
7774 {
7781 #ifdef LOAD_EXTEND_OP
7783 && !flag_syntax_only
7786 {
7790 }
7791 #endif
7792 }
7794 {
7800 }
7801 }
7803 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
7804 T2 being pointers to types of the same size. */
7809 {
7821 }
7823 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7824 of the same precision, and X is a integer type not narrower than
7825 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7832 {
7837 }
7860 /* Convert fabs((double)float) into (double)fabsf(float). */
7863 {
7868 targ0));
7869 }
7870 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7876 /* Strip sign ops from argument. */
7878 {
7882 }
7889 {
7894 }
7896 {
7901 }
7911 /* Convert ~ (-A) to A - 1. */
7915 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7922 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7939 /* The argument to invert_truthvalue must have Boolean type. */
7943 /* Note that the operand of this must be an int
7944 and its values must be 0 or 1.
7945 ("true" is a fixed value perhaps depending on the language,
7946 but we don't handle values other than 1 correctly yet.) */
7961 {
7969 }
7971 {
7975 }
7977 {
7981 {
7990 }
7991 }
8003 {
8011 }
8013 {
8017 }
8019 {
8023 {
8032 }
8033 }
8039 }
8041 /* Fold a binary expression of code CODE and type TYPE with operands
8042 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8043 Return the folded expression if folding is successful. Otherwise,
8044 return NULL_TREE. */
8046 static tree
8048 {
8055 else
8058 /* MIN (MAX (a, b), b) == b. */
8063 /* MIN (MAX (b, a), b) == b. */
8069 /* MIN (a, MAX (a, b)) == a. */
8075 /* MIN (a, MAX (b, a)) == a. */
8082 }
8084 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8085 by changing CODE to reduce the magnitude of constants involved in
8086 ARG0 of the comparison.
8087 Returns a canonicalized comparison tree if a simplification was
8088 possible, otherwise returns NULL_TREE.
8089 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8090 valid if signed overflow is undefined. */
8092 static tree
8096 {
8102 /* Match A +- CST code arg1 and CST code arg1. */
8109 /* Identify the constant in arg0 and its sign. */
8112 else
8116 /* Overflowed constants and zero will cause problems. */
8121 /* See if we can reduce the magnitude of the constant in
8122 arg0 by changing the comparison code. */
8124 {
8125 /* CST <= arg1 -> CST-1 < arg1. */
8128 /* -CST < arg1 -> -CST-1 <= arg1. */
8131 /* CST > arg1 -> CST-1 >= arg1. */
8134 /* -CST >= arg1 -> -CST-1 > arg1. */
8137 else
8139 /* arg1 code' CST' might be more canonical. */
8141 }
8142 else
8143 {
8144 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8148 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8152 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8156 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8160 else
8163 }
8165 /* Now build the constant reduced in magnitude. */
8171 /* If swapping might yield to a more canonical form, do so. */
8174 else
8176 }
8178 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8179 overflow further. Try to decrease the magnitude of constants involved
8180 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8181 and put sole constants at the second argument position.
8182 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8184 static tree
8187 {
8188 tree t;
8193 /* In principle pointers also have undefined overflow behavior,
8194 but that causes problems elsewhere. */
8199 /* Try canonicalization by simplifying arg0. */
8204 {
8208 }
8210 /* Try canonicalization by simplifying arg1 using the swapped
8211 comparison. */
8219 }
8221 /* Subroutine of fold_binary. This routine performs all of the
8222 transformations that are common to the equality/inequality
8223 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8224 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8225 fold_binary should call fold_binary. Fold a comparison with
8226 tree code CODE and type TYPE with operands OP0 and OP1. Return
8227 the folded comparison or NULL_TREE. */
8229 static tree
8231 {
8244 /* If one arg is a real or integer constant, put it last. */
8248 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8255 {
8259 tree lhs;
8266 /* If the constant operation overflowed this can be
8267 simplified as a comparison against INT_MAX/INT_MIN. */
8270 {
8274 /* Get the sign of the constant on the lhs if the
8275 operation were VARIABLE + CONST1. */
8279 /* The sign of the constant determines if we overflowed
8280 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8281 Canonicalize to the INT_MIN overflow by swapping the comparison
8282 if necessary. */
8286 /* We now can look at the canonicalized case
8287 VARIABLE + 1 CODE2 INT_MIN
8288 and decide on the result. */
8297 }
8302 {
8304 "when changing X +- C1 cmp C2 to "
8306 WARN_STRICT_OVERFLOW_COMPARISON);
8308 }
8309 }
8311 /* For comparisons of pointers we can decompose it to a compile time
8312 comparison of the base objects and the offsets into the object.
8313 This requires at least one operand being an ADDR_EXPR to do more
8314 than the operand_equal_p test below. */
8318 {
8325 /* Get base and offset for the access. Strip ADDR_EXPR for
8326 get_inner_reference, but put it back by stripping INDIRECT_REF
8327 off the base object if possible. */
8330 {
8336 else
8338 }
8342 {
8346 /* We have to make sure to have an indirect/non-indirect base1
8347 just the same as we did for base0. */
8353 }
8357 /* If we have equivalent bases we might be able to simplify. */
8360 {
8361 /* We can fold this expression to a constant if the non-constant
8362 offset parts are equal. */
8366 {
8368 {
8382 }
8383 }
8384 /* We can simplify the comparison to a comparison of the variable
8385 offset parts if the constant offset parts are equal.
8386 Be careful to use signed size type here because otherwise we
8387 mess with array offsets in the wrong way. This is possible
8388 because pointer arithmetic is restricted to retain within an
8389 object and overflow on pointer differences is undefined as of
8390 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8392 {
8393 tree signed_size_type_node;
8396 /* By converting to signed size type we cover middle-end pointer
8397 arithmetic which operates on unsigned pointer types of size
8398 type size and ARRAY_REF offsets which are properly sign or
8399 zero extended from their type in case it is narrower than
8400 size type. */
8403 else
8407 else
8411 }
8412 }
8413 }
8415 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8416 same object, then we can fold this to a comparison of the two offsets in
8417 signed size type. This is possible because pointer arithmetic is
8418 restricted to retain within an object and overflow on pointer differences
8419 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8421 We check flag_wrapv directly because pointers types are unsigned,
8422 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8423 normally what we want to avoid certain odd overflow cases, but
8424 not here. */
8426 && !flag_wrapv
8428 {
8434 {
8435 tree signed_size_type_node;
8438 /* By converting to signed size type we cover middle-end pointer
8439 arithmetic which operates on unsigned pointer types of size
8440 type size and ARRAY_REF offsets which are properly sign or
8441 zero extended from their type in case it is narrower than
8442 size type. */
8445 else
8449 else
8453 }
8454 }
8456 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8457 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8458 the resulting offset is smaller in absolute value than the
8459 original one. */
8467 {
8472 tree cst;
8474 "occur when combining constants around "
8477 /* Put the constant on the side where it doesn't overflow and is
8478 of lower absolute value than before. */
8484 {
8487 variable1,
8490 }
8497 {
8502 variable2);
8503 }
8504 }
8506 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8507 signed arithmetic case. That form is created by the compiler
8508 often enough for folding it to be of value. One example is in
8509 computing loop trip counts after Operator Strength Reduction. */
8515 {
8524 "eliminating multiplication in comparison "
8526 WARN_STRICT_OVERFLOW_COMPARISON);
8528 /* If const1 is negative we swap the sense of the comparison. */
8533 }
8540 {
8548 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8553 /* (-a) CMP (-b) -> b CMP a */
8560 {
8561 REAL_VALUE_TYPE cst;
8564 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8571 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8572 /* a CMP (-0) -> a CMP 0 */
8577 /* x != NaN is always true, other ops are always false. */
8580 {
8583 }
8585 /* Fold comparisons against infinity. */
8587 {
8591 }
8592 }
8594 /* If this is a comparison of a real constant with a PLUS_EXPR
8595 or a MINUS_EXPR of a real constant, we can convert it into a
8596 comparison with a revised real constant as long as no overflow
8597 occurs when unsafe_math_optimizations are enabled. */
8609 /* Likewise, we can simplify a comparison of a real constant with
8610 a MINUS_EXPR whose first operand is also a real constant, i.e.
8611 (c1 - x) < c2 becomes x > c1-c2. */
8622 /* Fold comparisons against built-in math functions. */
8624 && flag_unsafe_math_optimizations
8626 {
8630 {
8634 }
8635 }
8636 }
8638 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
8642 /* This optimization is invalid for ordered comparisons
8643 if CONST+INCR overflows or if foo+incr might overflow.
8644 This optimization is invalid for floating point due to rounding.
8645 For pointer types we assume overflow doesn't happen. */
8649 {
8653 {
8659 }
8660 else
8661 {
8667 }
8670 /* If VAROP is a reference to a bitfield, we must mask
8671 the constant by the width of the field. */
8676 {
8681 /* First check whether the comparison would come out
8682 always the same. If we don't do that we would
8683 change the meaning with the masking. */
8696 }
8699 }
8704 {
8705 /* If we are widening one operand of an integer comparison,
8706 see if the other operand is similarly being widened. Perhaps we
8707 can do the comparison in the narrower type. */
8712 /* Or if we are changing signedness. */
8716 }
8718 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8719 constant, we can simplify it. */
8724 {
8728 }
8730 /* Simplify comparison of something with itself. (For IEEE
8731 floating-point, we can only do some of these simplifications.) */
8733 {
8735 {
8750 /* For NE, we can only do this simplification if integer
8751 or we don't honor IEEE floating point NaNs. */
8755 /* ... fall through ... */
8761 }
8762 }
8764 /* If we are comparing an expression that just has comparisons
8765 of two integer values, arithmetic expressions of those comparisons,
8766 and constants, we can simplify it. There are only three cases
8767 to check: the two values can either be equal, the first can be
8768 greater, or the second can be greater. Fold the expression for
8769 those three values. Since each value must be 0 or 1, we have
8770 eight possibilities, each of which corresponds to the constant 0
8771 or 1 or one of the six possible comparisons.
8773 This handles common cases like (a > b) == 0 but also handles
8774 expressions like ((x > y) - (y > x)) > 0, which supposedly
8775 occur in macroized code. */
8778 {
8783 /* Don't handle degenerate cases here; they should already
8784 have been handled anyway. */
8793 {
8797 /* We can't just pass T to eval_subst in case cval1 or cval2
8798 was the same as ARG1. */
8800 tree high_result
8804 arg1);
8805 tree equal_result
8809 arg1);
8810 tree low_result
8814 arg1);
8816 /* All three of these results should be 0 or 1. Confirm they are.
8817 Then use those values to select the proper code to use. */
8822 {
8823 /* Make a 3-bit mask with the high-order bit being the
8824 value for `>', the next for '=', and the low for '<'. */
8828 {
8830 /* Always false. */
8851 /* Always true. */
8853 }
8858 }
8859 }
8860 }
8862 /* If this is a comparison of complex values and both sides
8863 are COMPLEX_CST, do the comparison by parts to fold the
8864 comparison. */
8869 {
8882 }
8885 /* Fold a comparison of the address of COMPONENT_REFs with the same
8886 type and component to a comparison of the address of the base
8887 object. In short, &x->a OP &y->a to x OP y and
8888 &x->a OP &y.a to x OP &y */
8893 {
8897 {
8903 }
8904 }
8906 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8907 into a single range test. */
8915 {
8919 }
8921 /* Fold ~X op ~Y as Y op X. */
8928 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
8936 }
8939 /* Subroutine of fold_binary. Optimize complex multiplications of the
8940 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8941 argument EXPR represents the expression "z" of type TYPE. */
8943 static tree
8945 {
8950 {
8953 }
8955 {
8958 }
8959 else
8960 {
8964 }
8973 }
8976 /* Fold a binary expression of code CODE and type TYPE with operands
8977 OP0 and OP1. Return the folded expression if folding is
8978 successful. Otherwise, return NULL_TREE. */
8980 tree
8982 {
8997 /* Strip any conversions that don't change the mode. This is
8998 safe for every expression, except for a comparison expression
8999 because its signedness is derived from its operands. So, in
9000 the latter case, only strip conversions that don't change the
9001 signedness.
9003 Note that this is done as an internal manipulation within the
9004 constant folder, in order to find the simplest representation
9005 of the arguments so that their form can be studied. In any
9006 cases, the appropriate type conversions should be put back in
9007 the tree that will get out of the constant folder. */
9010 {
9013 }
9014 else
9015 {
9018 }
9020 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9021 constant but we can't do arithmetic on them. */
9026 {
9031 else
9035 {
9039 }
9040 }
9042 /* If this is a commutative operation, and ARG0 is a constant, move it
9043 to ARG1 to reduce the number of tests below. */
9048 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9050 First check for cases where an arithmetic operation is applied to a
9051 compound, conditional, or comparison operation. Push the arithmetic
9052 operation inside the compound or conditional to see if any folding
9053 can then be done. Convert comparison to conditional for this purpose.
9054 The also optimizes non-constant cases that used to be done in
9055 expand_expr.
9057 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9058 one of the operands is a comparison and the other is a comparison, a
9059 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9060 code below would make the expression more complex. Change it to a
9061 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9062 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9074 {
9078 boolean_type_node,
9086 }
9090 {
9102 {
9108 }
9111 {
9117 }
9118 }
9121 {
9123 /* A + (-B) -> A - B */
9128 /* (-A) + B -> B - A */
9134 /* Convert ~A + 1 to -A. */
9140 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9141 same or one. */
9145 {
9149 }
9152 {
9156 /* ~X + X is -1. */
9160 {
9163 }
9165 /* X + ~X is -1. */
9169 {
9172 }
9174 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9175 with a constant, and the two constants have no bits in common,
9176 we should treat this as a BIT_IOR_EXPR since this may produce more
9177 simplifications. */
9185 {
9188 }
9190 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9191 (plus (plus (mult) (mult)) (foo)) so that we can
9192 take advantage of the factoring cases below. */
9199 {
9205 else
9227 parg1)));
9228 }
9230 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
9231 of the array. Loop optimizer sometimes produce this type of
9232 expressions. */
9234 {
9238 }
9240 {
9244 }
9245 }
9246 else
9247 {
9248 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9252 /* Likewise if the operands are reversed. */
9256 /* Convert X + -C into X - C. */
9259 {
9265 }
9267 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9268 to __complex__ ( x, y ). This is not the same for SNaNs or
9269 if signed zeros are involved. */
9273 {
9280 {
9284 {
9290 }
9292 {
9298 }
9299 }
9300 }
9308 /* Convert x+x into x*2.0. */
9314 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
9318 {
9323 {
9324 tree tree0;
9327 }
9328 }
9329 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
9333 {
9338 {
9339 tree tree0;
9342 }
9343 }
9344 }
9346 bit_rotate:
9347 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9348 is a rotate of A by C1 bits. */
9349 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9350 is a rotate of A by B bits. */
9351 {
9360 {
9379 {
9387 TYPE_PRECISION
9392 ? LROTATE_EXPR
9395 }
9397 {
9405 TYPE_PRECISION
9410 ? LROTATE_EXPR
9413 }
9414 }
9415 }
9417 associate:
9418 /* In most languages, can't associate operations on floats through
9419 parentheses. Rather than remember where the parentheses were, we
9420 don't associate floats at all, unless the user has specified
9421 -funsafe-math-optimizations. */
9424 {
9429 /* Split both trees into variables, constants, and literals. Then
9430 associate each group together, the constants with literals,
9431 then the result with variables. This increases the chances of
9432 literals being recombined later and of generating relocatable
9433 expressions for the sum of a constant and literal. */
9438 /* With undefined overflow we can only associate constants
9439 with one variable. */
9443 {
9451 /* The only case we can still associate with two variables
9452 is if they are the same, modulo negation. */
9455 }
9457 /* Only do something if we found more than two objects. Otherwise,
9458 nothing has changed and we risk infinite recursion. */
9464 {
9465 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9474 /* Preserve the MINUS_EXPR if the negative part of the literal is
9475 greater than the positive part. Otherwise, the multiplicative
9476 folding code (i.e extract_muldiv) may be fooled in case
9477 unsigned constants are subtracted, like in the following
9478 example: ((X*2 + 4) - 8U)/2. */
9480 {
9484 {
9488 }
9489 else
9490 {
9494 }
9495 }
9497 {
9502 else
9503 {
9509 }
9510 }
9515 }
9516 }
9521 /* A - (-B) -> A + B */
9524 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9532 /* Convert -A - 1 to ~A. */
9540 /* Convert -1 - A to ~A. */
9546 {
9552 /* Fold A - (A & B) into ~B & A. */
9555 {
9560 arg0);
9565 arg0);
9566 }
9568 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9569 any power of 2 minus 1. */
9574 {
9580 {
9584 }
9585 }
9586 }
9588 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9592 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9593 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9594 (-ARG1 + ARG0) reduces to -ARG1. */
9598 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9599 __complex__ ( x, -y ). This is not the same for SNaNs or if
9600 signed zeros are involved. */
9604 {
9611 {
9615 {
9617 arg1r ? arg1r
9622 }
9624 {
9628 arg1i ? arg1i
9631 }
9632 }
9633 }
9635 /* Fold &x - &x. This can happen from &x.foo - &x.
9636 This is unsafe for certain floats even in non-IEEE formats.
9637 In IEEE, it is unsafe because it does wrong for NaNs.
9638 Also note that operand_equal_p is always false if an operand
9639 is volatile. */
9645 /* A - B -> A + (-B) if B is easily negatable. */
9648 /* Avoid this transformation if B is a positive REAL_CST. */
9656 /* Try folding difference of addresses. */
9657 {
9658 HOST_WIDE_INT diff;
9664 }
9666 /* Fold &a[i] - &a[j] to i-j. */
9671 {
9676 {
9684 }
9685 }
9687 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9688 of the array. Loop optimizer sometimes produce this type of
9689 expressions. */
9691 {
9695 }
9703 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9704 same or one. */
9708 {
9712 }
9717 /* (-A) * (-B) -> A * B */
9728 {
9733 /* Transform x * -1 into -x. */
9736 /* Transform x * -C into -x * C if x is easily negatable. */
9745 /* (a * (1 << b)) is (a << b) */
9761 {
9764 "occur when simplifying "
9766 WARN_STRICT_OVERFLOW_MISC);
9768 }
9770 /* Optimize z * conj(z) for integer complex numbers. */
9777 }
9778 else
9779 {
9780 /* Maybe fold x * 0 to 0. The expressions aren't the same
9781 when x is NaN, since x * 0 is also NaN. Nor are they the
9782 same in modes with signed zeros, since multiplying a
9783 negative value by 0 gives -0, not +0. */
9788 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9793 /* Transform x * -1.0 into -x. */
9798 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9803 {
9809 }
9811 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9813 {
9816 {
9819 }
9820 }
9822 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9823 This is not the same for NaNs or if signed zeros are
9824 involved. */
9830 {
9842 }
9844 /* Optimize z * conj(z) for floating point complex numbers.
9845 Guarded by flag_unsafe_math_optimizations as non-finite
9846 imaginary components don't produce scalar results. */
9857 {
9861 /* Optimizations of root(...)*root(...). */
9863 {
9868 /* Optimize sqrt(x)*sqrt(x) as x. */
9874 /* Optimize root(x)*root(y) as root(x*y). */
9878 }
9880 /* Optimize expN(x)*expN(y) as expN(x+y). */
9882 {
9888 }
9890 /* Optimizations of pow(...)*pow(...). */
9894 {
9900 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9902 {
9906 }
9908 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9910 {
9914 }
9915 }
9917 /* Optimize tan(x)*cos(x) as sin(x). */
9926 {
9931 }
9933 /* Optimize x*pow(x,c) as pow(x,c+1). */
9937 {
9943 {
9945 REAL_VALUE_TYPE c;
9946 tree arg;
9952 }
9953 }
9955 /* Optimize pow(x,c)*x as pow(x,c+1). */
9959 {
9965 {
9967 REAL_VALUE_TYPE c;
9968 tree arg;
9974 }
9975 }
9977 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9980 {
9984 {
9987 }
9988 }
9989 }
9990 }
9994 bit_ior:
10002 /* ~X | X is -1. */
10005 {
10008 }
10010 /* X | ~X is -1. */
10013 {
10016 }
10018 /* Canonicalize (X & C1) | C2. */
10022 {
10030 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10035 {
10039 }
10040 else
10041 {
10045 }
10047 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10052 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
10062 arg1);
10063 }
10065 /* (X & Y) | Y is (X, Y). */
10069 /* (X & Y) | X is (Y, X). */
10074 /* X | (X & Y) is (Y, X). */
10079 /* X | (Y & X) is (Y, X). */
10089 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10091 This results in more efficient code for machines without a NAND
10092 instruction. Combine will canonicalize to the first form
10093 which will allow use of NAND instructions provided by the
10094 backend if they exist. */
10097 {
10102 }
10104 /* See if this can be simplified into a rotate first. If that
10105 is unsuccessful continue in the association code. */
10116 /* ~X ^ X is -1. */
10119 {
10122 }
10124 /* X ^ ~X is -1. */
10127 {
10130 }
10132 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10133 with a constant, and the two constants have no bits in common,
10134 we should treat this as a BIT_IOR_EXPR since this may produce more
10135 simplifications. */
10143 {
10146 }
10148 /* (X | Y) ^ X -> Y & ~ X*/
10151 {
10154 arg1);
10158 }
10160 /* (Y | X) ^ X -> Y & ~ X*/
10163 {
10166 arg1);
10170 }
10172 /* X ^ (X | Y) -> Y & ~ X*/
10175 {
10178 arg0);
10182 }
10184 /* X ^ (Y | X) -> Y & ~ X*/
10187 {
10190 arg0);
10194 }
10196 /* Convert ~X ^ ~Y to X ^ Y. */
10203 /* Convert ~X ^ C to X ^ ~C. */
10210 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10217 /* Fold (X & Y) ^ Y as ~X & Y. */
10220 {
10225 }
10226 /* Fold (X & Y) ^ X as ~Y & X. */
10230 {
10235 }
10236 /* Fold X ^ (X & Y) as X & ~Y. */
10239 {
10244 }
10245 /* Fold X ^ (Y & X) as ~Y & X. */
10249 {
10254 }
10256 /* See if this can be simplified into a rotate first. If that
10257 is unsuccessful continue in the association code. */
10268 /* ~X & X is always zero. */
10273 /* X & ~X is always zero. */
10278 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10288 /* (X | Y) & Y is (X, Y). */
10292 /* (X | Y) & X is (Y, X). */
10297 /* X & (X | Y) is (Y, X). */
10302 /* X & (Y | X) is (Y, X). */
10308 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10312 {
10318 }
10319 /* Fold ~X & 1 as (X & 1) == 0. */
10322 {
10328 }
10330 /* Fold (X ^ Y) & Y as ~X & Y. */
10333 {
10338 }
10339 /* Fold (X ^ Y) & X as ~Y & X. */
10343 {
10348 }
10349 /* Fold X & (X ^ Y) as X & ~Y. */
10352 {
10357 }
10358 /* Fold X & (Y ^ X) as ~Y & X. */
10362 {
10367 }
10372 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10375 {
10376 unsigned int prec
10383 }
10385 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10387 This results in more efficient code for machines without a NOR
10388 instruction. Combine will canonicalize to the first form
10389 which will allow use of NOR instructions provided by the
10390 backend if they exist. */
10393 {
10398 }
10403 /* Don't touch a floating-point divide by zero unless the mode
10404 of the constant can represent infinity. */
10410 /* Optimize A / A to 1.0 if we don't care about
10411 NaNs or Infinities. Skip the transformation
10412 for non-real operands. */
10417 {
10421 }
10423 /* The complex version of the above A / A optimization. */
10426 {
10430 {
10432 /* omit_two_operands will call fold_convert for us. */
10434 }
10435 }
10437 /* (-A) / (-B) -> A / B */
10447 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
10452 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
10457 /* If ARG1 is a constant, we can convert this to a multiply by the
10458 reciprocal. This does not have the same rounding properties,
10459 so only do this if -funsafe-math-optimizations. We can actually
10460 always safely do it if ARG1 is a power of two, but it's hard to
10461 tell if it is or not in a portable manner. */
10463 {
10468 /* Find the reciprocal if optimizing and the result is exact. */
10470 {
10471 REAL_VALUE_TYPE r;
10474 {
10478 }
10479 }
10480 }
10481 /* Convert A/B/C to A/(B*C). */
10488 /* Convert A/(B/C) to (A/B)*C. */
10496 /* Convert C1/(X*C2) into (C1/C2)/X. */
10501 {
10507 }
10510 {
10514 /* Optimize sin(x)/cos(x) as tan(x). */
10520 {
10525 }
10527 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10533 {
10537 {
10541 }
10542 }
10544 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10545 NaNs or Infinities. */
10549 {
10556 {
10561 }
10562 }
10564 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10565 NaNs or Infinities. */
10569 {
10576 {
10580 {
10584 tmp);
10585 }
10586 }
10587 }
10589 /* Optimize pow(x,c)/x as pow(x,c-1). */
10593 {
10599 {
10601 REAL_VALUE_TYPE c;
10602 tree arg;
10608 }
10609 }
10611 /* Optimize x/expN(y) into x*expN(-y). */
10613 {
10618 }
10620 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10624 {
10631 }
10632 }
10637 /* Simplify A / (B << N) where A and B are positive and B is
10638 a power of 2, to A >> (N + log2(B)). */
10643 {
10646 {
10653 WARN_STRICT_OVERFLOW_MISC);
10659 }
10660 }
10661 /* Fall thru */
10670 /* X / -1 is -X. */
10677 /* Convert -A / -B to A / B when the type is signed and overflow is
10678 undefined. */
10682 {
10685 "when distributing negation across "
10687 WARN_STRICT_OVERFLOW_MISC);
10690 }
10694 {
10697 "when distributing negation across "
10699 WARN_STRICT_OVERFLOW_MISC);
10702 }
10704 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10705 operation, EXACT_DIV_EXPR.
10707 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10708 At one time others generated faster code, it's not clear if they do
10709 after the last round to changes to the DIV code in expmed.c. */
10718 {
10722 WARN_STRICT_OVERFLOW_MISC);
10724 }
10732 /* X % 1 is always zero, but be sure to preserve any side
10733 effects in X. */
10737 /* X % 0, return X % 0 unchanged so that we can get the
10738 proper warnings and errors. */
10742 /* 0 % X is always zero, but be sure to preserve any side
10743 effects in X. Place this after checking for X == 0. */
10747 /* X % -1 is zero. */
10754 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10755 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10760 {
10762 /* Also optimize A % (C << N) where C is a power of 2,
10763 to A & ((C << N) - 1). */
10768 {
10773 "occur when simplifying "
10775 WARN_STRICT_OVERFLOW_MISC);
10779 }
10780 }
10782 /* X % -C is the same as X % C. */
10789 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10794 /* X % -Y is the same as X % Y. */
10805 {
10809 WARN_STRICT_OVERFLOW_MISC);
10811 }
10822 /* Optimize -1 >> x for arithmetic right shifts. */
10825 /* ... fall through ... */
10828 shift:
10834 /* Since negative shift count is not well-defined,
10835 don't try to compute it in the compiler. */
10839 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10844 {
10848 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10849 being well defined. */
10851 {
10856 else
10858 }
10862 }
10864 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10865 into x & ((unsigned)-1 >> c) for unsigned types. */
10873 {
10876 tree lshift;
10877 tree arg00;
10880 {
10887 }
10888 }
10890 /* Rewrite an LROTATE_EXPR by a constant into an
10891 RROTATE_EXPR by a new constant. */
10893 {
10898 }
10900 /* If we have a rotate of a bit operation with the rotate count and
10901 the second operand of the bit operation both constant,
10902 permute the two operations. */
10914 /* Two consecutive rotates adding up to the width of the mode can
10915 be ignored. */
10952 /* Note that the operands of this must be ints
10953 and their values must be 0 or 1.
10954 ("true" is a fixed value perhaps depending on the language.) */
10955 /* If first arg is constant zero, return it. */
10959 /* If either arg is constant true, drop it. */
10963 /* Preserve sequence points. */
10966 /* If second arg is constant zero, result is zero, but first arg
10967 must be evaluated. */
10970 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10971 case will be handled here. */
10975 /* !X && X is always false. */
10979 /* X && !X is always false. */
10984 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10985 means A >= Y && A != MAX, but in this case we know that
10986 A < X <= MAX. */
10990 {
10998 }
11000 truth_andor:
11001 /* We only do these simplifications if we are optimizing. */
11005 /* Check for things like (A || B) && (A || C). We can convert this
11006 to A || (B && C). Note that either operator can be any of the four
11007 truth and/or operations and the transformation will still be
11008 valid. Also note that we only care about order for the
11009 ANDIF and ORIF operators. If B contains side effects, this
11010 might change the truth-value of A. */
11017 {
11037 /* This case if tricky because we must either have commutative
11038 operators or else A10 must not have side-effects. */
11044 a01);
11045 }
11047 /* See if we can build a range comparison. */
11051 /* Check for the possibility of merging component references. If our
11052 lhs is another similar operation, try to merge its rhs with our
11053 rhs. Then try to merge our lhs and rhs. */
11065 /* Note that the operands of this must be ints
11066 and their values must be 0 or true.
11067 ("true" is a fixed value perhaps depending on the language.) */
11068 /* If first arg is constant true, return it. */
11072 /* If either arg is constant zero, drop it. */
11076 /* Preserve sequence points. */
11079 /* If second arg is constant true, result is true, but we must
11080 evaluate first arg. */
11083 /* Likewise for first arg, but note this only occurs here for
11084 TRUTH_OR_EXPR. */
11088 /* !X || X is always true. */
11092 /* X || !X is always true. */
11100 /* If the second arg is constant zero, drop it. */
11103 /* If the second arg is constant true, this is a logical inversion. */
11105 {
11106 /* Only call invert_truthvalue if operand is a truth value. */
11109 else
11112 }
11113 /* Identical arguments cancel to zero. */
11117 /* !X ^ X is always true. */
11122 /* X ^ !X is always true. */
11135 /* bool_var != 0 becomes bool_var. */
11140 /* bool_var == 1 becomes bool_var. */
11145 /* bool_var != 1 becomes !bool_var. */
11150 /* bool_var == 0 becomes !bool_var. */
11155 /* If this is an equality comparison of the address of a non-weak
11156 object against zero, then we know the result. */
11163 /* If this is an equality comparison of the address of two non-weak,
11164 unaliased symbols neither of which are extern (since we do not
11165 have access to attributes for externs), then we know the result. */
11178 {
11179 /* We know that we're looking at the address of two
11180 non-weak, unaliased, static _DECL nodes.
11182 It is both wasteful and incorrect to call operand_equal_p
11183 to compare the two ADDR_EXPR nodes. It is wasteful in that
11184 all we need to do is test pointer equality for the arguments
11185 to the two ADDR_EXPR nodes. It is incorrect to use
11186 operand_equal_p as that function is NOT equivalent to a
11187 C equality test. It can in fact return false for two
11188 objects which would test as equal using the C equality
11189 operator. */
11193 type);
11194 }
11196 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
11197 a MINUS_EXPR of a constant, we can convert it into a comparison with
11198 a revised constant as long as no overflow occurs. */
11210 /* Similarly for a NEGATE_EXPR. */
11218 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11227 /* Transform comparisons of the form X +- C CMP X. */
11233 {
11240 else
11243 }
11245 /* If we have X - Y == 0, we can convert that to X == Y and similarly
11246 for !=. Don't do this for ordered comparisons due to overflow. */
11252 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11257 /* If this is an EQ or NE comparison with zero and ARG0 is
11258 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11259 two operations, but the latter can be done in one less insn
11260 on machines that have only two-operand insns or on which a
11261 constant cannot be the first operand. */
11264 {
11269 return
11275 integer_one_node)),
11276 arg1);
11279 return
11285 integer_one_node)),
11286 arg1);
11287 }
11289 /* If this is an NE or EQ comparison of zero against the result of a
11290 signed MOD operation whose second operand is a power of 2, make
11291 the MOD operation unsigned since it is simpler and equivalent. */
11299 {
11309 }
11311 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11312 C1 is a valid shift constant, and C2 is a power of two, i.e.
11313 a single bit. */
11317 == INTEGER_CST
11320 {
11325 /* Check for a valid shift count. */
11328 {
11332 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11333 can be rewritten as (X & (C2 << C1)) != 0. */
11335 {
11339 }
11340 /* Otherwise, for signed (arithmetic) shifts,
11341 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11342 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11346 /* Otherwise, of unsigned (logical) shifts,
11347 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11348 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11349 else
11353 arg000);
11354 }
11355 }
11357 /* If this is an NE comparison of zero with an AND of one, remove the
11358 comparison since the AND will give the correct value. */
11365 /* If we have (A & C) == C where C is a power of 2, convert this into
11366 (A & C) != 0. Similarly for NE_EXPR. */
11372 integer_zero_node));
11374 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11375 bit, then fold the expression into A < 0 or A >= 0. */
11380 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11381 Similarly for NE_EXPR. */
11385 {
11394 }
11396 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11397 Similarly for NE_EXPR. */
11401 {
11408 }
11410 /* If this is a comparison of a field, we may be able to simplify it. */
11413 /* Handle the constant case even without -O
11414 to make sure the warnings are given. */
11416 {
11420 }
11422 /* Optimize comparisons of strlen vs zero to a compare of the
11423 first character of the string vs zero. To wit,
11424 strlen(ptr) == 0 => *ptr == 0
11425 strlen(ptr) != 0 => *ptr != 0
11426 Other cases should reduce to one of these two (or a constant)
11427 due to the return value of strlen being unsigned. */
11430 {
11438 {
11442 }
11443 }
11445 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11446 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11450 {
11457 {
11459 {
11462 }
11465 }
11466 }
11468 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
11474 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
11479 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
11486 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
11494 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11495 (X & C) == 0 when C is a single bit. */
11500 {
11506 }
11508 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11509 constant C is a power of two, i.e. a single bit. */
11516 {
11520 }
11522 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11523 when is C is a power of two, i.e. a single bit. */
11530 {
11536 }
11540 {
11543 }
11545 /* Fold -X op -Y as X op Y, where op is eq/ne. */
11552 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11555 {
11567 arg01),
11575 arg01),
11583 arg00),
11591 arg00),
11593 }
11597 {
11604 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11605 operand_equal_p guarantees no side-effects so we don't need
11606 to use omit_one_operand on Z. */
11616 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11623 arg10);
11624 }
11635 /* Transform comparisons of the form X +- C CMP X. */
11642 {
11649 else
11652 /* (X - c) > X becomes false. */
11656 {
11660 "occur when assuming that (X - c) > X "
11662 WARN_STRICT_OVERFLOW_ALL);
11664 }
11666 /* Likewise (X + c) < X becomes false. */
11670 {
11674 "occur when assuming that "
11676 WARN_STRICT_OVERFLOW_ALL);
11678 }
11680 /* Convert (X - c) <= X to true. */
11685 {
11689 "occur when assuming that "
11691 WARN_STRICT_OVERFLOW_ALL);
11693 }
11695 /* Convert (X + c) >= X to true. */
11700 {
11704 "occur when assuming that "
11706 WARN_STRICT_OVERFLOW_ALL);
11708 }
11711 {
11712 /* Convert X + c > X and X - c < X to true for integers. */
11716 {
11719 "not occur when assuming that "
11721 WARN_STRICT_OVERFLOW_ALL);
11723 }
11728 {
11731 "not occur when assuming that "
11733 WARN_STRICT_OVERFLOW_ALL);
11735 }
11737 /* Convert X + c <= X and X - c >= X to false for integers. */
11741 {
11744 "not occur when assuming that "
11746 WARN_STRICT_OVERFLOW_ALL);
11748 }
11753 {
11756 "not occur when assuming that "
11758 WARN_STRICT_OVERFLOW_ALL);
11760 }
11761 }
11762 }
11764 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11765 This transformation affects the cases which are handled in later
11766 optimizations involving comparisons with non-negative constants. */
11770 {
11772 {
11777 }
11779 {
11784 }
11785 }
11787 /* Comparisons with the highest or lowest possible integer of
11788 the specified precision will have known values. */
11789 {
11797 {
11798 HOST_WIDE_INT signed_max_hi;
11803 {
11810 {
11814 }
11815 else
11816 {
11820 }
11821 }
11822 else
11823 {
11832 {
11835 }
11836 else
11837 {
11840 }
11841 }
11846 {
11859 /* The GE_EXPR and LT_EXPR cases above are not normally
11860 reached because of previous transformations. */
11864 }
11866 == max_hi
11869 {
11880 }
11882 == min_hi
11885 {
11900 }
11902 == min_hi
11905 {
11914 }
11919 /* We will flip the signedness of the comparison operator
11920 associated with the mode of arg1, so the sign bit is
11921 specified by this mode. Check that arg1 is the signed
11922 max associated with this sign bit. */
11924 /* signed_type does not work on pointer types. */
11926 {
11927 /* The following case also applies to X < signed_max+1
11928 and X >= signed_max+1 because previous transformations. */
11930 {
11937 }
11938 }
11939 }
11940 }
11942 /* If we are comparing an ABS_EXPR with a constant, we can
11943 convert all the cases into explicit comparisons, but they may
11944 well not be faster than doing the ABS and one comparison.
11945 But ABS (X) <= C is a range comparison, which becomes a subtraction
11946 and a comparison, and is probably faster. */
11960 /* Convert ABS_EXPR<x> >= 0 to true. */
11967 {
11970 "when simplifying comparison of "
11972 WARN_STRICT_OVERFLOW_CONDITIONAL);
11974 }
11976 /* Convert ABS_EXPR<x> < 0 to false. */
11981 {
11984 "when simplifying comparison of "
11986 WARN_STRICT_OVERFLOW_CONDITIONAL);
11988 }
11990 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11991 and similarly for >= into !=. */
12007 return
12026 {
12030 }
12032 /* If the first operand is NaN, the result is constant. */
12036 {
12038 ? integer_zero_node
12041 }
12043 /* If the second operand is NaN, the result is constant. */
12047 {
12049 ? integer_zero_node
12052 }
12054 /* Simplify unordered comparison of something with itself. */
12060 && !flag_trapping_math
12064 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12065 {
12076 }
12081 /* When pedantic, a compound expression can be neither an lvalue
12082 nor an integer constant expression. */
12085 /* Don't let (0, 0) be null pointer constant. */
12099 /* An ASSERT_EXPR should never be passed to fold_binary. */
12105 }
12107 /* Callback for walk_tree, looking for LABEL_EXPR.
12108 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
12109 Do not check the sub-tree of GOTO_EXPR. */
12111 static tree
12115 {
12117 {
12122 /* no break */
12125 }
12126 }
12128 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
12129 accessible from outside the sub-tree. Returns NULL_TREE if no
12130 addressable label is found. */
12132 static bool
12134 {
12136 }
12138 /* Fold a ternary expression of code CODE and type TYPE with operands
12139 OP0, OP1, and OP2. Return the folded expression if folding is
12140 successful. Otherwise, return NULL_TREE. */
12142 tree
12144 {
12145 tree tem;
12152 /* Strip any conversions that don't change the mode. This is safe
12153 for every expression, except for a comparison expression because
12154 its signedness is derived from its operands. So, in the latter
12155 case, only strip conversions that don't change the signedness.
12157 Note that this is done as an internal manipulation within the
12158 constant folder, in order to find the simplest representation of
12159 the arguments so that their form can be studied. In any cases,
12160 the appropriate type conversions should be put back in the tree
12161 that will get out of the constant folder. */
12163 {
12166 }
12169 {
12172 }
12175 {
12179 {
12185 }
12189 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12190 so all simple results must be passed through pedantic_non_lvalue. */
12192 {
12195 /* Only optimize constant conditions when the selected branch
12196 has the same type as the COND_EXPR. This avoids optimizing
12197 away "c ? x : throw", where the throw has a void type.
12198 Avoid throwing away that operand which contains label. */
12205 }
12209 /* If we have A op B ? A : C, we may be able to convert this to a
12210 simpler expression, depending on the operation and the values
12211 of B and C. Signed zeros prevent all of these transformations,
12212 for reasons given above each one.
12214 Also try swapping the arguments and inverting the conditional. */
12219 {
12223 }
12227 op2,
12230 {
12233 {
12237 }
12238 }
12240 /* If the second operand is simpler than the third, swap them
12241 since that produces better jump optimization results. */
12244 {
12245 /* See if this can be inverted. If it can't, possibly because
12246 it was a floating-point inequality comparison, don't do
12247 anything. */
12251 }
12253 /* Convert A ? 1 : 0 to simply A. */
12256 /* If we try to convert OP0 to our type, the
12257 call to fold will try to move the conversion inside
12258 a COND, which will recurse. In that case, the COND_EXPR
12259 is probably the best choice, so leave it alone. */
12263 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12264 over COND_EXPR in cases such as floating point comparisons. */
12271 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12276 {
12277 /* sign_bit_p only checks ARG1 bits within A's precision.
12278 If <sign bit of A> has wider type than A, bits outside
12279 of A's precision in <sign bit of A> need to be checked.
12280 If they are all 0, this optimization needs to be done
12281 in unsigned A's type, if they are all 1 in signed A's type,
12282 otherwise this can't be done. */
12287 {
12289 HOST_WIDE_INT mask_hi;
12291 tree tem_type;
12299 {
12303 }
12304 else
12305 {
12309 }
12311 {
12315 }
12316 else
12322 {
12325 }
12328 {
12331 }
12332 else
12334 }
12341 arg1)));
12342 }
12344 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12345 already handled above. */
12350 {
12359 }
12361 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12362 is probably obsolete because the first operand should be a
12363 truth value (that's why we have the two cases above), but let's
12364 leave it in until we can confirm this for all front-ends. */
12375 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12381 arg1);
12383 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12387 {
12388 /* Only perform transformation if ARG0 is easily inverted. */
12393 arg1);
12394 }
12396 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
12400 {
12401 /* Only perform transformation if ARG0 is easily inverted. */
12406 op2);
12407 }
12409 /* Convert A ? 1 : B into A || B if A and B are truth values. */
12415 op2);
12420 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
12421 of fold_ternary on them. */
12429 {
12438 {
12444 else
12446 }
12447 }
12453 }
12455 /* Perform constant folding and related simplification of EXPR.
12456 The related simplifications include x*1 => x, x*0 => 0, etc.,
12457 and application of the associative law.
12458 NOP_EXPR conversions may be removed freely (as long as we
12459 are careful not to change the type of the overall expression).
12460 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12461 but we can constant-fold them if they have constant operands. */
12463 #ifdef ENABLE_FOLD_CHECKING
12464 # define fold(x) fold_1 (x)
12466 static
12467 #endif
12468 tree
12470 {
12474 tree tem;
12476 /* Return right away if a constant. */
12480 /* CALL_EXPR-like objects with variable numbers of operands are
12481 treated specially. */
12483 {
12485 {
12488 }
12490 }
12494 {
12499 {
12517 }
12518 }
12521 {
12528 }
12530 #ifdef ENABLE_FOLD_CHECKING
12531 #undef fold
12537 /* When --enable-checking=fold, compute a digest of expr before
12538 and after actual fold call to see if fold did not accidentally
12539 change original expr. */
12541 tree
12543 {
12544 tree ret;
12547 htab_t ht;
12566 }
12568 void
12570 {
12573 htab_t ht;
12583 }
12585 static void
12587 {
12589 }
12591 static void
12593 {
12599 recursive_label:
12613 {
12614 /* Allow DECL_ASSEMBLER_NAME to be modified. */
12618 }
12623 {
12624 /* Allow these fields to be modified. */
12631 {
12634 }
12635 }
12643 {
12646 {
12660 }
12664 {
12677 }
12694 {
12700 }
12705 {
12709 }
12720 {
12723 }
12733 }
12734 }
12736 #endif
12738 /* Fold a unary tree expression with code CODE of type TYPE with an
12739 operand OP0. Return a folded expression if successful. Otherwise,
12740 return a tree expression with code CODE of type TYPE with an
12741 operand OP0. */
12743 tree
12745 {
12746 tree tem;
12747 #ifdef ENABLE_FOLD_CHECKING
12750 htab_t ht;
12757 #endif
12763 #ifdef ENABLE_FOLD_CHECKING
12771 #endif
12773 }
12775 /* Fold a binary tree expression with code CODE of type TYPE with
12776 operands OP0 and OP1. Return a folded expression if successful.
12777 Otherwise, return a tree expression with code CODE of type TYPE
12778 with operands OP0 and OP1. */
12780 tree
12782 MEM_STAT_DECL)
12783 {
12784 tree tem;
12785 #ifdef ENABLE_FOLD_CHECKING
12791 htab_t ht;
12803 #endif
12809 #ifdef ENABLE_FOLD_CHECKING
12825 #endif
12827 }
12829 /* Fold a ternary tree expression with code CODE of type TYPE with
12830 operands OP0, OP1, and OP2. Return a folded expression if
12831 successful. Otherwise, return a tree expression with code CODE of
12832 type TYPE with operands OP0, OP1, and OP2. */
12834 tree
12836 MEM_STAT_DECL)
12837 {
12838 tree tem;
12839 #ifdef ENABLE_FOLD_CHECKING
12847 htab_t ht;
12864 #endif
12871 #ifdef ENABLE_FOLD_CHECKING
12895 #endif
12897 }
12899 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12900 arguments in ARGARRAY, and a null static chain.
12901 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12902 of type TYPE from the given operands as constructed by build_call_array. */
12904 tree
12906 {
12907 tree tem;
12908 #ifdef ENABLE_FOLD_CHECKING
12914 htab_t ht;
12928 #endif
12932 #ifdef ENABLE_FOLD_CHECKING
12949 #endif
12951 }
12953 /* Perform constant folding and related simplification of initializer
12954 expression EXPR. These behave identically to "fold_buildN" but ignore
12955 potential run-time traps and exceptions that fold must preserve. */
12957 #define START_FOLD_INIT \
12958 int saved_signaling_nans = flag_signaling_nans;\
12959 int saved_trapping_math = flag_trapping_math;\
12960 int saved_rounding_math = flag_rounding_math;\
12961 int saved_trapv = flag_trapv;\
12962 int saved_folding_initializer = folding_initializer;\
12963 flag_signaling_nans = 0;\
12964 flag_trapping_math = 0;\
12965 flag_rounding_math = 0;\
12966 flag_trapv = 0;\
12967 folding_initializer = 1;
12969 #define END_FOLD_INIT \
12970 flag_signaling_nans = saved_signaling_nans;\
12971 flag_trapping_math = saved_trapping_math;\
12972 flag_rounding_math = saved_rounding_math;\
12973 flag_trapv = saved_trapv;\
12974 folding_initializer = saved_folding_initializer;
12976 tree
12978 {
12979 tree result;
12980 START_FOLD_INIT;
12984 END_FOLD_INIT;
12986 }
12988 tree
12990 {
12991 tree result;
12992 START_FOLD_INIT;
12996 END_FOLD_INIT;
12998 }
13000 tree
13002 tree op2)
13003 {
13004 tree result;
13005 START_FOLD_INIT;
13009 END_FOLD_INIT;
13011 }
13013 tree
13016 {
13017 tree result;
13018 START_FOLD_INIT;
13022 END_FOLD_INIT;
13024 }
13026 #undef START_FOLD_INIT
13027 #undef END_FOLD_INIT
13029 /* Determine if first argument is a multiple of second argument. Return 0 if
13030 it is not, or we cannot easily determined it to be.
13032 An example of the sort of thing we care about (at this point; this routine
13033 could surely be made more general, and expanded to do what the *_DIV_EXPR's
13034 fold cases do now) is discovering that
13036 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13038 is a multiple of
13040 SAVE_EXPR (J * 8)
13042 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13044 This code also handles discovering that
13046 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13048 is a multiple of 8 so we don't have to worry about dealing with a
13049 possible remainder.
13051 Note that we *look* inside a SAVE_EXPR only to determine how it was
13052 calculated; it is not safe for fold to do much of anything else with the
13053 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13054 at run time. For example, the latter example above *cannot* be implemented
13055 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13056 evaluation time of the original SAVE_EXPR is not necessarily the same at
13057 the time the new expression is evaluated. The only optimization of this
13058 sort that would be valid is changing
13060 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13062 divided by 8 to
13064 SAVE_EXPR (I) * SAVE_EXPR (J)
13066 (where the same SAVE_EXPR (J) is used in the original and the
13067 transformed version). */
13069 static int
13071 {
13079 {
13081 /* Bitwise and provides a power of two multiple. If the mask is
13082 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13085 /* FALLTHRU */
13098 {
13102 /* const_binop may not detect overflow correctly,
13103 so check for it explicitly here. */
13109 size_one_node,
13113 }
13117 /* Can't handle conversions from non-integral or wider integral type. */
13123 /* .. fall through ... */
13139 }
13140 }
13142 /* Return true if `t' is known to be non-negative. If the return
13143 value is based on the assumption that signed overflow is undefined,
13144 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13145 *STRICT_OVERFLOW_P. */
13147 bool
13149 {
13157 {
13159 /* Query VRP to see if it has recorded any information about
13160 the range of this object. */
13164 /* We can't return 1 if flag_wrapv is set because
13165 ABS_EXPR<INT_MIN> = INT_MIN. */
13169 {
13172 }
13184 strict_overflow_p)
13186 strict_overflow_p));
13188 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13189 both unsigned and at least 2 bits shorter than the result. */
13193 {
13198 {
13202 }
13203 }
13208 {
13209 /* x * x for floating point x is always non-negative. */
13213 strict_overflow_p)
13215 strict_overflow_p));
13216 }
13218 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13219 both unsigned and their total bits is shorter than the result. */
13223 {
13230 }
13236 strict_overflow_p)
13238 strict_overflow_p));
13249 strict_overflow_p)
13251 strict_overflow_p));
13261 strict_overflow_p);
13267 strict_overflow_p);
13271 strict_overflow_p);
13275 strict_overflow_p)
13277 strict_overflow_p));
13280 {
13285 {
13288 strict_overflow_p);
13290 {
13294 strict_overflow_p);
13295 }
13296 }
13298 {
13301 strict_overflow_p);
13305 }
13306 }
13310 {
13314 /* If the initializer is non-void, then it's a normal expression
13315 that will be assigned to the slot. */
13319 /* Otherwise, the initializer sets the slot in some way. One common
13320 way is an assignment statement at the end of the initializer. */
13322 {
13330 else
13332 }
13337 strict_overflow_p);
13340 }
13343 {
13347 {
13365 /* Always true. */
13369 /* sqrt(-0.0) is -0.0. */
13373 strict_overflow_p);
13406 /* True if the 1st argument is nonnegative. */
13408 strict_overflow_p);
13411 /* True if the 1st OR 2nd arguments are nonnegative. */
13413 strict_overflow_p)
13415 strict_overflow_p)));
13418 /* True if the 1st AND 2nd arguments are nonnegative. */
13420 strict_overflow_p)
13422 strict_overflow_p)));
13425 /* True if the 2nd argument is nonnegative. */
13427 strict_overflow_p);
13430 /* True if the 1st argument is nonnegative or the second
13431 argument is an even integer. */
13433 {
13437 }
13439 strict_overflow_p);
13442 /* True if the 1st argument is nonnegative or the second
13443 argument is an even integer valued real. */
13445 {
13446 REAL_VALUE_TYPE c;
13447 HOST_WIDE_INT n;
13452 {
13453 REAL_VALUE_TYPE cint;
13458 }
13459 }
13461 strict_overflow_p);
13465 }
13466 }
13468 /* ... fall through ... */
13472 /* Truth values evaluate to 0 or 1, which is nonnegative. */
13474 }
13476 /* We don't know sign of `t', so be conservative and return false. */
13478 }
13480 /* Return true if `t' is known to be non-negative. Handle warnings
13481 about undefined signed overflow. */
13483 bool
13485 {
13492 "determining that expression is always "
13494 WARN_STRICT_OVERFLOW_MISC);
13496 }
13498 /* Return true when T is an address and is known to be nonzero.
13499 For floating point we further ensure that T is not denormal.
13500 Similar logic is present in nonzero_address in rtlanal.h.
13502 If the return value is based on the assumption that signed overflow
13503 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13504 change *STRICT_OVERFLOW_P. */
13506 bool
13508 {
13512 /* Doing something useful for floating point would need more work. */
13517 {
13519 /* Query VRP to see if it has recorded any information about
13520 the range of this object. */
13525 strict_overflow_p);
13532 {
13533 /* With the presence of negative values it is hard
13534 to say something. */
13541 /* One of operands must be positive and the other non-negative. */
13542 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13543 overflows, on a twos-complement machine the sum of two
13544 nonnegative numbers can never be zero. */
13546 strict_overflow_p)
13548 strict_overflow_p));
13549 }
13554 {
13556 strict_overflow_p)
13558 strict_overflow_p))
13559 {
13562 }
13563 }
13567 {
13573 strict_overflow_p));
13574 }
13578 {
13584 /* Weak declarations may link to NULL. */
13588 /* Constants are never weak. */
13593 }
13601 {
13605 }
13614 {
13617 }
13624 {
13628 /* When both operands are nonzero, then MAX must be too. */
13630 strict_overflow_p))
13633 /* MAX where operand 0 is positive is positive. */
13635 strict_overflow_p);
13636 }
13637 /* MAX where operand 1 is positive is positive. */
13642 {
13646 }
13654 strict_overflow_p);
13659 strict_overflow_p);
13663 strict_overflow_p)
13665 strict_overflow_p));
13672 }
13674 }
13676 /* Return true when T is an address and is known to be nonzero.
13677 Handle warnings about undefined signed overflow. */
13679 bool
13681 {
13688 "determining that expression is always "
13690 WARN_STRICT_OVERFLOW_MISC);
13692 }
13694 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13695 attempt to fold the expression to a constant without modifying TYPE,
13696 OP0 or OP1.
13698 If the expression could be simplified to a constant, then return
13699 the constant. If the expression would not be simplified to a
13700 constant, then return NULL_TREE. */
13702 tree
13704 {
13707 }
13709 /* Given the components of a unary expression CODE, TYPE and OP0,
13710 attempt to fold the expression to a constant without modifying
13711 TYPE or OP0.
13713 If the expression could be simplified to a constant, then return
13714 the constant. If the expression would not be simplified to a
13715 constant, then return NULL_TREE. */
13717 tree
13719 {
13722 }
13724 /* If EXP represents referencing an element in a constant string
13725 (either via pointer arithmetic or array indexing), return the
13726 tree representing the value accessed, otherwise return NULL. */
13728 tree
13730 {
13734 {
13736 tree index;
13737 tree string;
13741 else
13742 {
13746 /* Optimize the special-case of a zero lower bound.
13748 We convert the low_bound to sizetype to avoid some problems
13749 with constant folding. (E.g. suppose the lower bound is 1,
13750 and its mode is QI. Without the conversion,l (ARRAY
13751 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13752 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
13757 }
13771 }
13773 }
13775 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13776 an integer constant or real constant.
13778 TYPE is the type of the result. */
13780 static tree
13782 {
13786 {
13788 {
13790 HOST_WIDE_INT high;
13798 }
13806 }
13809 }
13811 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13812 an integer constant or real constant.
13814 TYPE is the type of the result. */
13816 tree
13818 {
13822 {
13824 /* If the value is unsigned, then the absolute value is
13825 the same as the ordinary value. */
13828 /* Similarly, if the value is non-negative. */
13831 /* If the value is negative, then the absolute value is
13832 its negation. */
13833 else
13834 {
13836 HOST_WIDE_INT high;
13842 }
13848 else
13854 }
13857 }
13859 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13860 constant. TYPE is the type of the result. */
13862 static tree
13864 {
13874 }
13876 /* Given CODE, a relational operator, the target type, TYPE and two
13877 constant operands OP0 and OP1, return the result of the
13878 relational operation. If the result is not a compile time
13879 constant, then return NULL_TREE. */
13881 static tree
13883 {
13886 /* From here on, the only cases we handle are when the result is
13887 known to be a constant. */
13890 {
13894 /* Handle the cases where either operand is a NaN. */
13896 {
13898 {
13926 }
13929 }
13932 }
13934 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13936 To compute GT, swap the arguments and do LT.
13937 To compute GE, do LT and invert the result.
13938 To compute LE, swap the arguments, do LT and invert the result.
13939 To compute NE, do EQ and invert the result.
13941 Therefore, the code below must handle only EQ and LT. */
13944 {
13949 }
13951 /* Note that it is safe to invert for real values here because we
13952 have already handled the one case that it matters. */
13956 {
13959 }
13961 /* Compute a result for LT or EQ if args permit;
13962 Otherwise return T. */
13964 {
13969 else
13971 }
13972 else
13978 }
13980 /* Build an expression for the a clean point containing EXPR with type TYPE.
13981 Don't build a cleanup point expression for EXPR which don't have side
13982 effects. */
13984 tree
13986 {
13987 /* If the expression does not have side effects then we don't have to wrap
13988 it with a cleanup point expression. */
13992 /* If the expression is a return, check to see if the expression inside the
13993 return has no side effects or the right hand side of the modify expression
13994 inside the return. If either don't have side effects set we don't need to
13995 wrap the expression in a cleanup point expression. Note we don't check the
13996 left hand side of the modify because it should always be a return decl. */
13998 {
14005 }
14008 }
14010 /* Build an expression for the address of T. Folds away INDIRECT_REF to
14011 avoid confusing the gimplify process. */
14013 tree
14015 {
14016 /* The size of the object is not relevant when talking about its address. */
14020 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
14023 {
14027 }
14028 else
14029 {
14038 }
14041 }
14043 tree
14045 {
14047 }
14049 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14050 of an indirection through OP0, or NULL_TREE if no simplification is
14051 possible. */
14053 tree
14055 {
14057 tree subtype;
14065 {
14068 /* *&CONST_DECL -> to the value of the const decl. */
14071 /* *&p => p; make sure to handle *&"str"[cst] here. */
14073 {
14077 else
14079 }
14080 /* *(foo *)&fooarray => fooarray[0] */
14083 {
14089 }
14090 /* *(foo *)&complexfoo => __real__ complexfoo */
14094 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14097 {
14101 }
14102 }
14104 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14107 {
14110 tree op00type;
14117 {
14121 }
14122 }
14124 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14127 {
14128 tree type_domain;
14135 }
14138 }
14140 /* Builds an expression for an indirection through T, simplifying some
14141 cases. */
14143 tree
14145 {
14151 else
14153 }
14155 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14157 tree
14159 {
14164 else
14166 }
14168 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14169 whose result is ignored. The type of the returned tree need not be
14170 the same as the original expression. */
14172 tree
14174 {
14180 {
14191 else
14197 {
14213 }
14218 }
14219 }
14221 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
14222 This can only be applied to objects of a sizetype. */
14224 tree
14226 {
14233 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14234 have to do anything. Only do this when we are not given a const,
14235 because in that case, this check is more expensive than just
14236 doing it. */
14238 {
14243 }
14245 /* If divisor is a power of two, simplify this to bit manipulation. */
14247 {
14249 {
14262 {
14263 high++;
14266 }
14270 }
14271 else
14272 {
14273 tree t;
14279 }
14280 }
14281 else
14282 {
14287 }
14290 }
14292 /* Likewise, but round down. */
14294 tree
14296 {
14303 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14304 have to do anything. Only do this when we are not given a const,
14305 because in that case, this check is more expensive than just
14306 doing it. */
14308 {
14313 }
14315 /* If divisor is a power of two, simplify this to bit manipulation. */
14317 {
14318 tree t;
14322 }
14323 else
14324 {
14329 }
14332 }
14334 /* Returns the pointer to the base of the object addressed by EXP and
14335 extracts the information about the offset of the access, storing it
14336 to PBITPOS and POFFSET. */
14338 static tree
14341 {
14342 tree core;
14345 HOST_WIDE_INT bitsize;
14348 {
14353 }
14354 else
14355 {
14359 }
14362 }
14364 /* Returns true if addresses of E1 and E2 differ by a constant, false
14365 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14367 bool
14369 {
14383 {
14393 }
14395 {
14396 /* If only one of the offsets is non-constant, the difference cannot
14397 be a constant. */
14399 }
14400 else
14405 }
14407 /* Simplify the floating point expression EXP when the sign of the
14408 result is not significant. Return NULL_TREE if no simplification
14409 is possible. */
14411 tree
14413 {
14417 {
14452 {
14455 {
14457 /* Strip copysign function call, return the 1st argument. */
14463 /* Strip sign ops from the argument of "odd" math functions. */
14465 {
14469 }
14471 }
14472 }
14477 }
14479 }