| blob | 7d66736b13b6b89e8160c60cb25c2d3ab56c94cf |
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 {
1393 }
1397 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1399 {
1404 {
1411 }
1412 }
1417 }
1420 }
1422 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1423 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1424 return NULL_TREE. */
1426 static tree
1428 {
1441 }
1442 \f
1443 /* Split a tree IN into a constant, literal and variable parts that could be
1444 combined with CODE to make IN. "constant" means an expression with
1445 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1446 commutative arithmetic operation. Store the constant part into *CONP,
1447 the literal in *LITP and return the variable part. If a part isn't
1448 present, set it to null. If the tree does not decompose in this way,
1449 return the entire tree as the variable part and the other parts as null.
1451 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1452 case, we negate an operand that was subtracted. Except if it is a
1453 literal for which we use *MINUS_LITP instead.
1455 If NEGATE_P is true, we are negating all of IN, again except a literal
1456 for which we use *MINUS_LITP instead.
1458 If IN is itself a literal or constant, return it as appropriate.
1460 Note that we do not guarantee that any of the three values will be the
1461 same type as IN, but they will have the same signedness and mode. */
1463 static tree
1466 {
1473 /* Strip any conversions that don't change the machine mode or signedness. */
1480 /* We can associate addition and subtraction together (even
1481 though the C standard doesn't say so) for integers because
1482 the value is not affected. For reals, the value might be
1483 affected, so we can't. */
1486 {
1492 /* First see if either of the operands is a literal, then a constant. */
1503 /* If we haven't dealt with either operand, this is not a case we can
1504 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1509 else
1512 /* Now do any needed negations. */
1519 }
1522 else
1526 {
1533 }
1536 }
1538 /* Re-associate trees split by the above function. T1 and T2 are either
1539 expressions to associate or null. Return the new expression, if any. If
1540 we build an operation, do it in TYPE and with CODE. */
1542 static tree
1544 {
1550 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1551 try to fold this since we will have infinite recursion. But do
1552 deal with any NEGATE_EXPRs. */
1555 {
1557 {
1566 }
1568 {
1571 }
1575 }
1579 }
1580 \f
1581 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1582 for use in int_const_binop, size_binop and size_diffop. */
1584 static bool
1586 {
1593 {
1602 }
1607 }
1610 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1611 to produce a new constant. Return NULL_TREE if we don't know how
1612 to evaluate CODE at compile-time.
1614 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1616 tree
1618 {
1622 HOST_WIDE_INT hi;
1624 HOST_WIDE_INT garbageh;
1625 tree t;
1628 int is_sizetype
1638 {
1654 /* It's unclear from the C standard whether shifts can overflow.
1655 The following code ignores overflow; perhaps a C standard
1656 interpretation ruling is needed. */
1685 /* This is a shortcut for a common special case. */
1690 {
1696 }
1698 /* ... fall through ... */
1704 {
1707 }
1710 {
1713 }
1720 /* This is a shortcut for a common special case. */
1725 {
1730 }
1732 /* ... fall through ... */
1750 else
1756 else
1762 }
1765 {
1768 /* Propagate overflow flags ourselves. */
1771 {
1774 }
1775 }
1776 else
1782 }
1784 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1785 constant. We assume ARG1 and ARG2 have the same data type, or at least
1786 are the same kind of constant and the same machine mode. Return zero if
1787 combining the constants is not allowed in the current operating mode.
1789 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1791 static tree
1793 {
1794 /* Sanity check for the recursive cases. */
1805 {
1807 REAL_VALUE_TYPE d1;
1808 REAL_VALUE_TYPE d2;
1809 REAL_VALUE_TYPE value;
1810 REAL_VALUE_TYPE result;
1814 /* The following codes are handled by real_arithmetic. */
1816 {
1827 }
1835 /* Don't perform operation if we honor signaling NaNs and
1836 either operand is a NaN. */
1841 /* Don't perform operation if it would raise a division
1842 by zero exception. */
1848 /* If either operand is a NaN, just return it. Otherwise, set up
1849 for floating-point trap; we return an overflow. */
1858 /* Don't constant fold this floating point operation if
1859 the result has overflowed and flag_trapping_math. */
1867 /* Don't constant fold this floating point operation if the
1868 result may dependent upon the run-time rounding mode and
1869 flag_rounding_math is set, or if GCC's software emulation
1870 is unable to accurately represent the result. */
1881 }
1884 {
1893 {
1904 notrunc);
1908 notrunc);
1912 {
1913 tree magsquared
1917 notrunc);
1918 tree t1
1922 notrunc);
1923 tree t2
1927 notrunc);
1934 }
1939 }
1943 }
1946 }
1948 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1949 indicates which particular sizetype to create. */
1951 tree
1953 {
1955 }
1956 \f
1957 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1958 is a tree code. The type of the result is taken from the operands.
1959 Both must be equivalent integer types, ala int_binop_types_match_p.
1960 If the operands are constant, so is the result. */
1962 tree
1964 {
1973 /* Handle the special case of two integer constants faster. */
1975 {
1976 /* And some specific cases even faster than that. */
1978 {
1983 }
1985 {
1988 }
1990 {
1993 }
1995 /* Handle general case of two integer constants. */
1997 }
2000 }
2002 /* Given two values, either both of sizetype or both of bitsizetype,
2003 compute the difference between the two values. Return the value
2004 in signed type corresponding to the type of the operands. */
2006 tree
2008 {
2010 tree ctype;
2015 /* If the type is already signed, just do the simple thing. */
2023 else
2026 /* If either operand is not a constant, do the conversions to the signed
2027 type and subtract. The hardware will do the right thing with any
2028 overflow in the subtraction. */
2033 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2034 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2035 overflow) and negate (which can't either). Special-case a result
2036 of zero while we're here. */
2041 else
2045 }
2046 \f
2047 /* A subroutine of fold_convert_const handling conversions of an
2048 INTEGER_CST to another integer type. */
2050 static tree
2052 {
2053 tree t;
2055 /* Given an integer constant, make new constant with new type,
2056 appropriately sign-extended or truncated. */
2059 /* Don't set the overflow when
2060 converting a pointer */
2068 }
2070 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2071 to an integer type. */
2073 static tree
2075 {
2077 tree t;
2079 /* The following code implements the floating point to integer
2080 conversion rules required by the Java Language Specification,
2081 that IEEE NaNs are mapped to zero and values that overflow
2082 the target precision saturate, i.e. values greater than
2083 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2084 are mapped to INT_MIN. These semantics are allowed by the
2085 C and C++ standards that simply state that the behavior of
2086 FP-to-integer conversion is unspecified upon overflow. */
2089 REAL_VALUE_TYPE r;
2093 {
2100 }
2102 /* If R is NaN, return zero and show we have an overflow. */
2104 {
2108 }
2110 /* See if R is less than the lower bound or greater than the
2111 upper bound. */
2114 {
2118 {
2122 }
2123 }
2126 {
2129 {
2132 {
2136 }
2137 }
2138 }
2146 }
2148 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2149 to another floating point type. */
2151 static tree
2153 {
2154 REAL_VALUE_TYPE value;
2155 tree t;
2162 }
2164 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2165 type TYPE. If no simplification can be done return NULL_TREE. */
2167 static tree
2169 {
2174 {
2179 }
2181 {
2186 }
2188 }
2190 /* Construct a vector of zero elements of vector type TYPE. */
2192 static tree
2194 {
2205 }
2207 /* Convert expression ARG to type TYPE. Used by the middle-end for
2208 simple conversions in preference to calling the front-end's convert. */
2210 tree
2212 {
2214 tree tem;
2230 {
2235 {
2239 }
2244 {
2247 }
2254 {
2258 }
2260 {
2264 }
2267 {
2282 }
2286 {
2295 {
2299 {
2303 }
2311 }
2315 }
2333 }
2334 }
2335 \f
2336 /* Return false if expr can be assumed not to be an lvalue, true
2337 otherwise. */
2339 static bool
2341 {
2342 /* We only need to wrap lvalue tree codes. */
2344 {
2379 /* Assume the worst for front-end tree codes. */
2383 }
2386 }
2388 /* Return an expr equal to X but certainly not valid as an lvalue. */
2390 tree
2392 {
2393 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2394 us. */
2401 }
2403 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2404 Zero means allow extended lvalues. */
2408 /* When pedantic, return an expr equal to X but certainly not valid as a
2409 pedantic lvalue. Otherwise, return X. */
2411 static tree
2413 {
2416 else
2418 }
2419 \f
2420 /* Given a tree comparison code, return the code that is the logical inverse
2421 of the given code. It is not safe to do this for floating-point
2422 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2423 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2425 enum tree_code
2427 {
2432 {
2463 }
2464 }
2466 /* Similar, but return the comparison that results if the operands are
2467 swapped. This is safe for floating-point. */
2469 enum tree_code
2471 {
2473 {
2499 }
2500 }
2503 /* Convert a comparison tree code from an enum tree_code representation
2504 into a compcode bit-based encoding. This function is the inverse of
2505 compcode_to_comparison. */
2507 static enum comparison_code
2509 {
2511 {
2542 }
2543 }
2545 /* Convert a compcode bit-based encoding of a comparison operator back
2546 to GCC's enum tree_code representation. This function is the
2547 inverse of comparison_to_compcode. */
2549 static enum tree_code
2551 {
2553 {
2584 }
2585 }
2587 /* Return a tree for the comparison which is the combination of
2588 doing the AND or OR (depending on CODE) of the two operations LCODE
2589 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2590 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2591 if this makes the transformation invalid. */
2593 tree
2597 {
2604 {
2615 }
2618 {
2619 /* Eliminate unordered comparisons, as well as LTGT and ORD
2620 which are not used unless the mode has NaNs. */
2626 }
2628 {
2629 /* Check that the original operation and the optimized ones will trap
2630 under the same condition. */
2641 /* In a short-circuited boolean expression the LHS might be
2642 such that the RHS, if evaluated, will never trap. For
2643 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2644 if neither x nor y is NaN. (This is a mixed blessing: for
2645 example, the expression above will never trap, hence
2646 optimizing it to x < y would be invalid). */
2651 /* If the comparison was short-circuited, and only the RHS
2652 trapped, we may now generate a spurious trap. */
2657 /* If we changed the conditions that cause a trap, we lose. */
2660 }
2666 else
2669 }
2671 /* Return nonzero if CODE is a tree code that represents a truth value. */
2673 static int
2675 {
2680 }
2681 \f
2682 /* Return nonzero if two operands (typically of the same tree node)
2683 are necessarily equal. If either argument has side-effects this
2684 function returns zero. FLAGS modifies behavior as follows:
2686 If OEP_ONLY_CONST is set, only return nonzero for constants.
2687 This function tests whether the operands are indistinguishable;
2688 it does not test whether they are equal using C's == operation.
2689 The distinction is important for IEEE floating point, because
2690 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2691 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2693 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2694 even though it may hold multiple values during a function.
2695 This is because a GCC tree node guarantees that nothing else is
2696 executed between the evaluation of its "operands" (which may often
2697 be evaluated in arbitrary order). Hence if the operands themselves
2698 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2699 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2700 unset means assuming isochronic (or instantaneous) tree equivalence.
2701 Unless comparing arbitrary expression trees, such as from different
2702 statements, this flag can usually be left unset.
2704 If OEP_PURE_SAME is set, then pure functions with identical arguments
2705 are considered the same. It is used when the caller has other ways
2706 to ensure that global memory is unchanged in between. */
2708 int
2710 {
2711 /* If either is ERROR_MARK, they aren't equal. */
2715 /* If both types don't have the same signedness, then we can't consider
2716 them equal. We must check this before the STRIP_NOPS calls
2717 because they may change the signedness of the arguments. */
2721 /* If both types don't have the same precision, then it is not safe
2722 to strip NOPs. */
2729 /* In case both args are comparisons but with different comparison
2730 code, try to swap the comparison operands of one arg to produce
2731 a match and compare that variant. */
2735 {
2743 }
2746 /* This is needed for conversions and for COMPONENT_REF.
2747 Might as well play it safe and always test this. */
2753 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2754 We don't care about side effects in that case because the SAVE_EXPR
2755 takes care of that for us. In all other cases, two expressions are
2756 equal if they have no side effects. If we have two identical
2757 expressions with side effects that should be treated the same due
2758 to the only side effects being identical SAVE_EXPR's, that will
2759 be detected in the recursive calls below. */
2765 /* Next handle constant cases, those for which we can return 1 even
2766 if ONLY_CONST is set. */
2769 {
2780 {
2781 /* If we do not distinguish between signed and unsigned zero,
2782 consider them equal. */
2785 }
2789 {
2795 {
2797 flags))
2801 }
2804 }
2808 flags)
2810 flags));
2823 }
2828 /* Define macros to test an operand from arg0 and arg1 for equality and a
2829 variant that allows null and views null as being different from any
2830 non-null value. In the latter case, if either is null, the both
2831 must be; otherwise, do the normal comparison. */
2832 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2833 TREE_OPERAND (arg1, N), flags)
2835 #define OP_SAME_WITH_NULL(N) \
2836 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2837 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2840 {
2842 /* Two conversions are equal only if signedness and modes match. */
2844 {
2854 }
2864 /* For commutative ops, allow the other order. */
2872 /* If either of the pointer (or reference) expressions we are
2873 dereferencing contain a side effect, these cannot be equal. */
2879 {
2889 /* Operands 2 and 3 may be null. */
2896 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2897 may be NULL when we're called to compare MEM_EXPRs. */
2907 }
2911 {
2926 /* Otherwise take into account this is a commutative operation. */
2933 /* If the CALL_EXPRs call different functions, then they
2934 clearly can not be equal. */
2938 {
2942 else
2946 }
2948 /* Now see if all the arguments are the same. operand_equal_p
2949 does not handle TREE_LIST, so we walk the operands here
2950 feeding them to operand_equal_p. */
2954 {
2956 flags))
2961 }
2963 /* If we get here and both argument lists are exhausted
2964 then the CALL_EXPRs are equal. */
2969 }
2972 /* Consider __builtin_sqrt equal to sqrt. */
2980 }
2982 #undef OP_SAME
2983 #undef OP_SAME_WITH_NULL
2984 }
2985 \f
2986 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2987 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2989 When in doubt, return 0. */
2991 static int
2993 {
3005 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3006 and see if the inner values are the same. This removes any
3007 signedness comparison, which doesn't matter here. */
3014 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3015 actual comparison operand, ARG0.
3017 First throw away any conversions to wider types
3018 already present in the operands. */
3027 {
3030 /* Make sure shorter operand is extended the right way
3031 to match the longer operand. */
3037 }
3040 }
3041 \f
3042 /* See if ARG is an expression that is either a comparison or is performing
3043 arithmetic on comparisons. The comparisons must only be comparing
3044 two different values, which will be stored in *CVAL1 and *CVAL2; if
3045 they are nonzero it means that some operands have already been found.
3046 No variables may be used anywhere else in the expression except in the
3047 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3048 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3050 If this is true, return 1. Otherwise, return zero. */
3052 static int
3054 {
3058 /* We can handle some of the tcc_expression cases here. */
3068 {
3069 /* If we've already found a CVAL1 or CVAL2, this expression is
3070 two complex to handle. */
3076 }
3079 {
3102 /* First see if we can handle the first operand, then the second. For
3103 the second operand, we know *CVAL1 can't be zero. It must be that
3104 one side of the comparison is each of the values; test for the
3105 case where this isn't true by failing if the two operands
3106 are the same. */
3115 ;
3119 ;
3120 else
3124 ;
3128 ;
3129 else
3136 }
3137 }
3138 \f
3139 /* ARG is a tree that is known to contain just arithmetic operations and
3140 comparisons. Evaluate the operations in the tree substituting NEW0 for
3141 any occurrence of OLD0 as an operand of a comparison and likewise for
3142 NEW1 and OLD1. */
3144 static tree
3146 {
3151 /* We can handle some of the tcc_expression cases here. */
3159 {
3174 {
3191 }
3192 /* Fall through - ??? */
3195 {
3199 /* We need to check both for exact equality and tree equality. The
3200 former will be true if the operand has a side-effect. In that
3201 case, we know the operand occurred exactly once. */
3214 }
3218 }
3219 }
3220 \f
3221 /* Return a tree for the case when the result of an expression is RESULT
3222 converted to TYPE and OMITTED was previously an operand of the expression
3223 but is now not needed (e.g., we folded OMITTED * 0).
3225 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3226 the conversion of RESULT to TYPE. */
3228 tree
3230 {
3237 }
3239 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3241 static tree
3243 {
3250 }
3252 /* Return a tree for the case when the result of an expression is RESULT
3253 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3254 of the expression but are now not needed.
3256 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3257 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3258 evaluated before OMITTED2. Otherwise, if neither has side effects,
3259 just do the conversion of RESULT to TYPE. */
3261 tree
3263 {
3272 }
3274 \f
3275 /* Return a simplified tree node for the truth-negation of ARG. This
3276 never alters ARG itself. We assume that ARG is an operation that
3277 returns a truth value (0 or 1).
3279 FIXME: one would think we would fold the result, but it causes
3280 problems with the dominator optimizer. */
3282 tree
3284 {
3288 /* If this is a comparison, we can simply invert it, except for
3289 floating-point non-equality comparisons, in which case we just
3290 enclose a TRUTH_NOT_EXPR around what we have. */
3293 {
3296 && flag_trapping_math
3300 else
3301 {
3306 else
3309 }
3310 }
3313 {
3328 /* Here we can invert either operand. We invert the first operand
3329 unless the second operand is a TRUTH_NOT_EXPR in which case our
3330 result is the XOR of the first operand with the inside of the
3331 negation of the second operand. */
3336 else
3355 {
3358 /* A COND_EXPR may have a throw as one operand, which
3359 then has void type. Just leave void operands
3360 as they are. */
3366 }
3399 }
3402 }
3404 /* Return a simplified tree node for the truth-negation of ARG. This
3405 never alters ARG itself. We assume that ARG is an operation that
3406 returns a truth value (0 or 1).
3408 FIXME: one would think we would fold the result, but it causes
3409 problems with the dominator optimizer. */
3411 tree
3413 {
3414 tree tem;
3424 }
3426 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3427 operands are another bit-wise operation with a common input. If so,
3428 distribute the bit operations to save an operation and possibly two if
3429 constants are involved. For example, convert
3430 (A | B) & (A | C) into A | (B & C)
3431 Further simplification will occur if B and C are constants.
3433 If this optimization cannot be done, 0 will be returned. */
3435 static tree
3437 {
3438 tree common;
3448 {
3452 }
3454 {
3458 }
3460 {
3464 }
3466 {
3470 }
3471 else
3476 }
3478 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3479 with code CODE. This optimization is unsafe. */
3480 static tree
3482 {
3486 /* (A / C) +- (B / C) -> (A +- B) / C. */
3496 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3501 {
3513 }
3516 }
3517 \f
3518 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3519 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3521 static tree
3524 {
3525 tree result;
3528 {
3535 }
3543 }
3545 /* Optimize a bit-field compare.
3547 There are two cases: First is a compare against a constant and the
3548 second is a comparison of two items where the fields are at the same
3549 bit position relative to the start of a chunk (byte, halfword, word)
3550 large enough to contain it. In these cases we can avoid the shift
3551 implicit in bitfield extractions.
3553 For constants, we emit a compare of the shifted constant with the
3554 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3555 compared. For two fields at the same position, we do the ANDs with the
3556 similar mask and compare the result of the ANDs.
3558 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3559 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3560 are the left and right operands of the comparison, respectively.
3562 If the optimization described above can be done, we return the resulting
3563 tree. Otherwise we return zero. */
3565 static tree
3568 {
3577 tree mask;
3578 tree offset;
3580 /* Get all the information about the extractions being done. If the bit size
3581 if the same as the size of the underlying object, we aren't doing an
3582 extraction at all and so can do nothing. We also don't want to
3583 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3584 then will no longer be able to replace it. */
3592 {
3593 /* If this is not a constant, we can only do something if bit positions,
3594 sizes, and signedness are the same. */
3602 }
3604 /* See if we can find a mode to refer to this field. We should be able to,
3605 but fail if we can't. */
3614 /* Set signed and unsigned types of the precision of this mode for the
3615 shifts below. */
3619 /* Compute the bit position and size for the new reference and our offset
3620 within it. If the new reference is the same size as the original, we
3621 won't optimize anything, so return zero. */
3631 /* Make the mask to be used against the extracted field. */
3638 /* If not comparing with constant, just rework the comparison
3639 and return. */
3643 unsigned_type,
3646 mask),
3649 unsigned_type,
3652 mask));
3654 /* Otherwise, we are handling the constant case. See if the constant is too
3655 big for the field. Warn and return a tree of for 0 (false) if so. We do
3656 this not only for its own sake, but to avoid having to test for this
3657 error case below. If we didn't, we might generate wrong code.
3659 For unsigned fields, the constant shifted right by the field length should
3660 be all zero. For signed fields, the high-order bits should agree with
3661 the sign bit. */
3664 {
3668 {
3672 }
3673 }
3674 else
3675 {
3679 {
3683 }
3684 }
3686 /* Single-bit compares should always be against zero. */
3688 {
3691 }
3693 /* Make a new bitfield reference, shift the constant over the
3694 appropriate number of bits and mask it with the computed mask
3695 (in case this was a signed field). If we changed it, make a new one. */
3698 {
3701 }
3711 rhs);
3712 }
3713 \f
3714 /* Subroutine for fold_truthop: decode a field reference.
3716 If EXP is a comparison reference, we return the innermost reference.
3718 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3719 set to the starting bit number.
3721 If the innermost field can be completely contained in a mode-sized
3722 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3724 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3725 otherwise it is not changed.
3727 *PUNSIGNEDP is set to the signedness of the field.
3729 *PMASK is set to the mask used. This is either contained in a
3730 BIT_AND_EXPR or derived from the width of the field.
3732 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3734 Return 0 if this is not a component reference or is one that we can't
3735 do anything with. */
3737 static tree
3742 {
3746 tree unsigned_type;
3749 /* All the optimizations using this function assume integer fields.
3750 There are problems with FP fields since the type_for_size call
3751 below can fail for, e.g., XFmode. */
3755 /* We are interested in the bare arrangement of bits, so strip everything
3756 that doesn't affect the machine mode. However, record the type of the
3757 outermost expression if it may matter below. */
3765 {
3771 }
3780 /* If the number of bits in the reference is the same as the bitsize of
3781 the outer type, then the outer type gives the signedness. Otherwise
3782 (in case of a small bitfield) the signedness is unchanged. */
3786 /* Compute the mask to access the bitfield. */
3795 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3803 }
3805 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3806 bit positions. */
3808 static int
3810 {
3813 tree tmask;
3817 return
3824 }
3826 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3827 represents the sign bit of EXP's type. If EXP represents a sign
3828 or zero extension, also test VAL against the unextended type.
3829 The return value is the (sub)expression whose sign bit is VAL,
3830 or NULL_TREE otherwise. */
3832 static tree
3834 {
3838 tree t;
3840 /* Tree EXP must have an integral type. */
3845 /* Tree VAL must be an integer constant. */
3852 {
3859 }
3860 else
3861 {
3868 }
3870 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3871 treat VAL as if it were unsigned. */
3876 /* Handle extension from a narrower type. */
3882 }
3884 /* Subroutine for fold_truthop: determine if an operand is simple enough
3885 to be evaluated unconditionally. */
3887 static int
3889 {
3890 /* Strip any conversions that don't change the machine mode. */
3899 /* Don't regard global variables as simple. They may be
3900 allocated in ways unknown to the compiler (shared memory,
3901 #pragma weak, etc). */
3904 /* Loading a static variable is unduly expensive, but global
3905 registers aren't expensive. */
3907 }
3908 \f
3909 /* The following functions are subroutines to fold_range_test and allow it to
3910 try to change a logical combination of comparisons into a range test.
3912 For example, both
3913 X == 2 || X == 3 || X == 4 || X == 5
3914 and
3915 X >= 2 && X <= 5
3916 are converted to
3917 (unsigned) (X - 2) <= 3
3919 We describe each set of comparisons as being either inside or outside
3920 a range, using a variable named like IN_P, and then describe the
3921 range with a lower and upper bound. If one of the bounds is omitted,
3922 it represents either the highest or lowest value of the type.
3924 In the comments below, we represent a range by two numbers in brackets
3925 preceded by a "+" to designate being inside that range, or a "-" to
3926 designate being outside that range, so the condition can be inverted by
3927 flipping the prefix. An omitted bound is represented by a "-". For
3928 example, "- [-, 10]" means being outside the range starting at the lowest
3929 possible value and ending at 10, in other words, being greater than 10.
3930 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3931 always false.
3933 We set up things so that the missing bounds are handled in a consistent
3934 manner so neither a missing bound nor "true" and "false" need to be
3935 handled using a special case. */
3937 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3938 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3939 and UPPER1_P are nonzero if the respective argument is an upper bound
3940 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3941 must be specified for a comparison. ARG1 will be converted to ARG0's
3942 type if both are specified. */
3944 static tree
3947 {
3948 tree tem;
3952 /* If neither arg represents infinity, do the normal operation.
3953 Else, if not a comparison, return infinity. Else handle the special
3954 comparison rules. Note that most of the cases below won't occur, but
3955 are handled for consistency. */
3958 {
3963 }
3968 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3969 for neither. In real maths, we cannot assume open ended ranges are
3970 the same. But, this is computer arithmetic, where numbers are finite.
3971 We can therefore make the transformation of any unbounded range with
3972 the value Z, Z being greater than any representable number. This permits
3973 us to treat unbounded ranges as equal. */
3977 {
3998 }
4001 }
4002 \f
4003 /* Given EXP, a logical expression, set the range it is testing into
4004 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4005 actually being tested. *PLOW and *PHIGH will be made of the same
4006 type as the returned expression. If EXP is not a comparison, we
4007 will most likely not be returning a useful value and range. Set
4008 *STRICT_OVERFLOW_P to true if the return value is only valid
4009 because signed overflow is undefined; otherwise, do not change
4010 *STRICT_OVERFLOW_P. */
4012 static tree
4015 {
4022 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4023 and see if we can refine the range. Some of the cases below may not
4024 happen, but it doesn't seem worth worrying about this. We "continue"
4025 the outer loop when we've changed something; otherwise we "break"
4026 the switch, which will "break" the while. */
4032 {
4037 {
4049 }
4052 {
4059 /* We can only do something if the range is testing for zero
4060 and if the second operand is an integer constant. Note that
4061 saying something is "in" the range we make is done by
4062 complementing IN_P since it will set in the initial case of
4063 being not equal to zero; "out" is leaving it alone. */
4070 {
4091 }
4093 /* If this is an unsigned comparison, we also know that EXP is
4094 greater than or equal to zero. We base the range tests we make
4095 on that fact, so we record it here so we can parse existing
4096 range tests. We test arg0_type since often the return type
4097 of, e.g. EQ_EXPR, is boolean. */
4099 {
4103 NULL_TREE))
4108 /* If the high bound is missing, but we have a nonzero low
4109 bound, reverse the range so it goes from zero to the low bound
4110 minus 1. */
4112 {
4117 }
4118 }
4124 /* (-x) IN [a,b] -> x in [-b, -a] */
4136 /* ~ X -> -X - 1 */
4145 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4146 move a constant to the other side. */
4151 /* If EXP is signed, any overflow in the computation is undefined,
4152 so we don't worry about it so long as our computations on
4153 the bounds don't overflow. For unsigned, overflow is defined
4154 and this is exactly the right thing. */
4166 /* Check for an unsigned range which has wrapped around the maximum
4167 value thus making n_high < n_low, and normalize it. */
4169 {
4175 /* If the range is of the form +/- [ x+1, x ], we won't
4176 be able to normalize it. But then, it represents the
4177 whole range or the empty set, so make it
4178 +/- [ -, - ]. */
4182 else
4184 }
4185 else
4209 /* If we're converting arg0 from an unsigned type, to exp,
4210 a signed type, we will be doing the comparison as unsigned.
4211 The tests above have already verified that LOW and HIGH
4212 are both positive.
4214 So we have to ensure that we will handle large unsigned
4215 values the same way that the current signed bounds treat
4216 negative values. */
4219 {
4220 tree high_positive;
4224 /* A range without an upper bound is, naturally, unbounded.
4225 Since convert would have cropped a very large value, use
4226 the max value for the destination type. */
4227 high_positive
4234 high_positive),
4237 /* If the low bound is specified, "and" the range with the
4238 range for which the original unsigned value will be
4239 positive. */
4241 {
4245 integer_zero_node),
4246 high_positive))
4250 }
4251 else
4252 {
4253 /* Otherwise, "or" the range with the range of the input
4254 that will be interpreted as negative. */
4258 integer_zero_node),
4259 high_positive))
4263 }
4264 }
4272 }
4275 }
4277 /* If EXP is a constant, we can evaluate whether this is true or false. */
4279 {
4286 }
4290 }
4291 \f
4292 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4293 type, TYPE, return an expression to test if EXP is in (or out of, depending
4294 on IN_P) the range. Return 0 if the test couldn't be created. */
4296 static tree
4298 {
4300 tree value;
4302 #ifdef HAVE_canonicalize_funcptr_for_compare
4303 /* Disable this optimization for function pointer expressions
4304 on targets that require function pointer canonicalization. */
4309 #endif
4312 {
4318 }
4336 {
4338 {
4342 }
4344 }
4346 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4348 {
4350 HOST_WIDE_INT hi;
4355 {
4358 }
4359 else
4360 {
4363 }
4366 {
4368 {
4371 }
4374 }
4375 }
4377 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4378 This requires wrap-around arithmetics for the type of the expression. */
4380 {
4382 /* There is no requirement that LOW be within the range of ETYPE
4383 if the latter is a subtype. It must, however, be within the base
4384 type of ETYPE. So be sure we do the subtraction in that type. */
4397 }
4399 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4402 {
4405 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4406 for the type in question, as we rely on this here. */
4416 else
4418 }
4432 }
4433 \f
4434 /* Return the predecessor of VAL in its type, handling the infinite case. */
4436 static tree
4438 {
4444 else
4446 }
4448 /* Return the successor of VAL in its type, handling the infinite case. */
4450 static tree
4452 {
4458 else
4460 }
4462 /* Given two ranges, see if we can merge them into one. Return 1 if we
4463 can, 0 if we can't. Set the output range into the specified parameters. */
4465 static int
4468 {
4472 tree tem;
4482 /* Make range 0 be the range that starts first, or ends last if they
4483 start at the same value. Swap them if it isn't. */
4486 || (lowequal
4489 {
4493 }
4495 /* Now flag two cases, whether the ranges are disjoint or whether the
4496 second range is totally subsumed in the first. Note that the tests
4497 below are simplified by the ones above. */
4503 /* We now have four cases, depending on whether we are including or
4504 excluding the two ranges. */
4506 {
4507 /* If they don't overlap, the result is false. If the second range
4508 is a subset it is the result. Otherwise, the range is from the start
4509 of the second to the end of the first. */
4514 else
4516 }
4519 {
4520 /* If they don't overlap, the result is the first range. If they are
4521 equal, the result is false. If the second range is a subset of the
4522 first, and the ranges begin at the same place, we go from just after
4523 the end of the second range to the end of the first. If the second
4524 range is not a subset of the first, or if it is a subset and both
4525 ranges end at the same place, the range starts at the start of the
4526 first range and ends just before the second range.
4527 Otherwise, we can't describe this as a single range. */
4533 {
4537 }
4539 {
4543 }
4544 else
4546 }
4549 {
4550 /* If they don't overlap, the result is the second range. If the second
4551 is a subset of the first, the result is false. Otherwise,
4552 the range starts just after the first range and ends at the
4553 end of the second. */
4558 else
4559 {
4563 }
4564 }
4566 else
4567 {
4568 /* The case where we are excluding both ranges. Here the complex case
4569 is if they don't overlap. In that case, the only time we have a
4570 range is if they are adjacent. If the second is a subset of the
4571 first, the result is the first. Otherwise, the range to exclude
4572 starts at the beginning of the first range and ends at the end of the
4573 second. */
4575 {
4580 else
4581 {
4582 /* Canonicalize - [min, x] into - [-, x]. */
4585 {
4590 /* FALLTHROUGH */
4603 }
4605 /* Canonicalize - [x, max] into - [x, -]. */
4608 {
4613 /* FALLTHROUGH */
4628 }
4630 /* The ranges might be also adjacent between the maximum and
4631 minimum values of the given type. For
4632 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4633 return + [x + 1, y - 1]. */
4635 {
4642 }
4643 else
4645 }
4646 }
4649 else
4651 }
4655 }
4656 \f
4658 /* Subroutine of fold, looking inside expressions of the form
4659 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4660 of the COND_EXPR. This function is being used also to optimize
4661 A op B ? C : A, by reversing the comparison first.
4663 Return a folded expression whose code is not a COND_EXPR
4664 anymore, or NULL_TREE if no folding opportunity is found. */
4666 static tree
4668 {
4673 tree tem;
4678 /* If we have A op 0 ? A : -A, consider applying the following
4679 transformations:
4681 A == 0? A : -A same as -A
4682 A != 0? A : -A same as A
4683 A >= 0? A : -A same as abs (A)
4684 A > 0? A : -A same as abs (A)
4685 A <= 0? A : -A same as -abs (A)
4686 A < 0? A : -A same as -abs (A)
4688 None of these transformations work for modes with signed
4689 zeros. If A is +/-0, the first two transformations will
4690 change the sign of the result (from +0 to -0, or vice
4691 versa). The last four will fix the sign of the result,
4692 even though the original expressions could be positive or
4693 negative, depending on the sign of A.
4695 Note that all these transformations are correct if A is
4696 NaN, since the two alternatives (A and -A) are also NaNs. */
4702 /* In the case that A is of the form X-Y, '-A' (arg2) may
4703 have already been folded to Y-X, check for that. */
4711 {
4723 /* Fall through. */
4745 }
4747 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4748 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4749 both transformations are correct when A is NaN: A != 0
4750 is then true, and A == 0 is false. */
4753 {
4758 }
4760 /* Try some transformations of A op B ? A : B.
4762 A == B? A : B same as B
4763 A != B? A : B same as A
4764 A >= B? A : B same as max (A, B)
4765 A > B? A : B same as max (B, A)
4766 A <= B? A : B same as min (A, B)
4767 A < B? A : B same as min (B, A)
4769 As above, these transformations don't work in the presence
4770 of signed zeros. For example, if A and B are zeros of
4771 opposite sign, the first two transformations will change
4772 the sign of the result. In the last four, the original
4773 expressions give different results for (A=+0, B=-0) and
4774 (A=-0, B=+0), but the transformed expressions do not.
4776 The first two transformations are correct if either A or B
4777 is a NaN. In the first transformation, the condition will
4778 be false, and B will indeed be chosen. In the case of the
4779 second transformation, the condition A != B will be true,
4780 and A will be chosen.
4782 The conversions to max() and min() are not correct if B is
4783 a number and A is not. The conditions in the original
4784 expressions will be false, so all four give B. The min()
4785 and max() versions would give a NaN instead. */
4787 /* Avoid these transformations if the COND_EXPR may be used
4788 as an lvalue in the C++ front-end. PR c++/19199. */
4789 && (in_gimple_form
4794 {
4799 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4801 {
4805 }
4808 {
4817 /* In C++ a ?: expression can be an lvalue, so put the
4818 operand which will be used if they are equal first
4819 so that we can convert this back to the
4820 corresponding COND_EXPR. */
4822 {
4829 }
4836 {
4843 }
4856 }
4857 }
4859 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4860 we might still be able to simplify this. For example,
4861 if C1 is one less or one more than C2, this might have started
4862 out as a MIN or MAX and been transformed by this function.
4863 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4869 {
4871 /* We can replace A with C1 in this case. */
4876 /* If C1 is C2 + 1, this is min(A, C2). */
4878 OEP_ONLY_CONST)
4882 OEP_ONLY_CONST))
4888 /* If C1 is C2 - 1, this is min(A, C2). */
4890 OEP_ONLY_CONST)
4894 OEP_ONLY_CONST))
4900 /* If C1 is C2 - 1, this is max(A, C2). */
4902 OEP_ONLY_CONST)
4906 OEP_ONLY_CONST))
4912 /* If C1 is C2 + 1, this is max(A, C2). */
4914 OEP_ONLY_CONST)
4918 OEP_ONLY_CONST))
4926 }
4929 }
4932 \f
4933 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4934 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4935 #endif
4937 /* EXP is some logical combination of boolean tests. See if we can
4938 merge it into some range test. Return the new tree if so. */
4940 static tree
4942 {
4950 tree tem;
4954 /* If this is an OR operation, invert both sides; we will invert
4955 again at the end. */
4959 /* If both expressions are the same, if we can merge the ranges, and we
4960 can build the range test, return it or it inverted. If one of the
4961 ranges is always true or always false, consider it to be the same
4962 expression as the other. */
4970 {
4974 }
4976 /* On machines where the branch cost is expensive, if this is a
4977 short-circuited branch and the underlying object on both sides
4978 is the same, make a non-short-circuit operation. */
4984 {
4985 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4986 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4987 which cases we can't do this. */
4995 {
5004 {
5007 WARN_STRICT_OVERFLOW_COMPARISON);
5011 }
5012 }
5013 }
5016 }
5017 \f
5018 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5019 bit value. Arrange things so the extra bits will be set to zero if and
5020 only if C is signed-extended to its full width. If MASK is nonzero,
5021 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5023 static tree
5025 {
5028 tree temp;
5033 /* We work by getting just the sign bit into the low-order bit, then
5034 into the high-order bit, then sign-extend. We then XOR that value
5035 with C. */
5039 /* We must use a signed type in order to get an arithmetic right shift.
5040 However, we must also avoid introducing accidental overflows, so that
5041 a subsequent call to integer_zerop will work. Hence we must
5042 do the type conversion here. At this point, the constant is either
5043 zero or one, and the conversion to a signed type can never overflow.
5044 We could get an overflow if this conversion is done anywhere else. */
5053 /* If necessary, convert the type back to match the type of C. */
5058 }
5059 \f
5060 /* Find ways of folding logical expressions of LHS and RHS:
5061 Try to merge two comparisons to the same innermost item.
5062 Look for range tests like "ch >= '0' && ch <= '9'".
5063 Look for combinations of simple terms on machines with expensive branches
5064 and evaluate the RHS unconditionally.
5066 For example, if we have p->a == 2 && p->b == 4 and we can make an
5067 object large enough to span both A and B, we can do this with a comparison
5068 against the object ANDed with the a mask.
5070 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5071 operations to do this with one comparison.
5073 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5074 function and the one above.
5076 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5077 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5079 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5080 two operands.
5082 We return the simplified tree or 0 if no optimization is possible. */
5084 static tree
5086 {
5087 /* If this is the "or" of two comparisons, we can do something if
5088 the comparisons are NE_EXPR. If this is the "and", we can do something
5089 if the comparisons are EQ_EXPR. I.e.,
5090 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5092 WANTED_CODE is this operation code. For single bit fields, we can
5093 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5094 comparison for one-bit fields. */
5116 /* Start by getting the comparison codes. Fail if anything is volatile.
5117 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5118 it were surrounded with a NE_EXPR. */
5127 {
5131 }
5134 {
5138 }
5149 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5152 {
5153 tree result;
5156 {
5161 }
5164 {
5170 }
5171 }
5176 /* If the RHS can be evaluated unconditionally and its operands are
5177 simple, it wins to evaluate the RHS unconditionally on machines
5178 with expensive branches. In this case, this isn't a comparison
5179 that can be merged. Avoid doing this if the RHS is a floating-point
5180 comparison since those can trap. */
5186 {
5187 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5197 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5208 {
5212 }
5213 }
5215 /* See if the comparisons can be merged. Then get all the parameters for
5216 each side. */
5240 /* It must be true that the inner operation on the lhs of each
5241 comparison must be the same if we are to be able to do anything.
5242 Then see if we have constants. If not, the same must be true for
5243 the rhs's. */
5254 else
5257 /* If either comparison code is not correct for our logical operation,
5258 fail. However, we can convert a one-bit comparison against zero into
5259 the opposite comparison against that bit being set in the field. */
5263 {
5265 {
5266 /* Make the left operand unsigned, since we are only interested
5267 in the value of one bit. Otherwise we are doing the wrong
5268 thing below. */
5271 }
5272 else
5274 }
5276 /* This is analogous to the code for l_const above. */
5278 {
5280 {
5283 }
5284 else
5286 }
5288 /* See if we can find a mode that contains both fields being compared on
5289 the left. If we can't, fail. Otherwise, update all constants and masks
5290 to be relative to a field of that size. */
5295 volatilep);
5305 {
5308 }
5316 {
5324 {
5328 }
5329 }
5331 {
5339 {
5343 }
5344 }
5346 /* If the right sides are not constant, do the same for it. Also,
5347 disallow this optimization if a size or signedness mismatch occurs
5348 between the left and right sides. */
5350 {
5353 /* Make sure the two fields on the right
5354 correspond to the left without being swapped. */
5362 volatilep);
5372 {
5375 }
5382 /* Make a mask that corresponds to both fields being compared.
5383 Do this for both items being compared. If the operands are the
5384 same size and the bits being compared are in the same position
5385 then we can do this by masking both and comparing the masked
5386 results. */
5390 {
5402 }
5404 /* There is still another way we can do something: If both pairs of
5405 fields being compared are adjacent, we may be able to make a wider
5406 field containing them both.
5408 Note that we still must mask the lhs/rhs expressions. Furthermore,
5409 the mask must be shifted to account for the shift done by
5410 make_bit_field_ref. */
5415 {
5416 tree type;
5428 /* Convert to the smaller type before masking out unwanted bits. */
5431 {
5433 {
5437 }
5439 {
5443 }
5444 }
5453 }
5456 }
5458 /* Handle the case of comparisons with constants. If there is something in
5459 common between the masks, those bits of the constants must be the same.
5460 If not, the condition is always false. Test for this to avoid generating
5461 incorrect code below. */
5466 {
5468 {
5471 }
5472 else
5473 {
5476 }
5477 }
5479 /* Construct the expression we will return. First get the component
5480 reference we will make. Unless the mask is all ones the width of
5481 that field, perform the mask operation. Then compare with the
5482 merged constant. */
5492 }
5493 \f
5494 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5495 constant. */
5497 static tree
5499 {
5503 tree minmax_const;
5505 tree inner;
5515 /* If something does not permit us to optimize, return the original tree. */
5523 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5524 and GT_EXPR, doing the rest with recursive calls using logical
5525 simplifications. */
5527 {
5529 {
5535 }
5538 return
5540 optimize_minmax_comparison
5542 optimize_minmax_comparison
5547 /* MAX (X, 0) == 0 -> X <= 0 */
5551 /* MAX (X, 0) == 5 -> X == 5 */
5555 /* MAX (X, 0) == -1 -> false */
5559 /* MIN (X, 0) == 0 -> X >= 0 */
5563 /* MIN (X, 0) == 5 -> false */
5566 else
5567 /* MIN (X, 0) == -1 -> X == -1 */
5572 /* MAX (X, 0) > 0 -> X > 0
5573 MAX (X, 0) > 5 -> X > 5 */
5577 /* MAX (X, 0) > -1 -> true */
5581 /* MIN (X, 0) > 0 -> false
5582 MIN (X, 0) > 5 -> false */
5585 else
5586 /* MIN (X, 0) > -1 -> X > -1 */
5591 }
5592 }
5593 \f
5594 /* T is an integer expression that is being multiplied, divided, or taken a
5595 modulus (CODE says which and what kind of divide or modulus) by a
5596 constant C. See if we can eliminate that operation by folding it with
5597 other operations already in T. WIDE_TYPE, if non-null, is a type that
5598 should be used for the computation if wider than our type.
5600 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5601 (X * 2) + (Y * 4). We must, however, be assured that either the original
5602 expression would not overflow or that overflow is undefined for the type
5603 in the language in question.
5605 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5606 the machine has a multiply-accumulate insn or that this is part of an
5607 addressing calculation.
5609 If we return a non-null expression, it is an equivalent form of the
5610 original computation, but need not be in the original type.
5612 We set *STRICT_OVERFLOW_P to true if the return values depends on
5613 signed overflow being undefined. Otherwise we do not change
5614 *STRICT_OVERFLOW_P. */
5616 static tree
5619 {
5620 /* To avoid exponential search depth, refuse to allow recursion past
5621 three levels. Beyond that (1) it's highly unlikely that we'll find
5622 something interesting and (2) we've probably processed it before
5623 when we built the inner expression. */
5626 tree ret;
5631 depth++;
5633 depth--;
5636 }
5638 static tree
5641 {
5652 /* Don't deal with constants of zero here; they confuse the code below. */
5662 /* Note that we need not handle conditional operations here since fold
5663 already handles those cases. So just do arithmetic here. */
5665 {
5667 /* For a constant, we can always simplify if we are a multiply
5668 or (for divide and modulus) if it is a multiple of our constant. */
5676 /* If op0 is an expression ... */
5681 /* ... and is unsigned, and its type is smaller than ctype,
5682 then we cannot pass through as widening. */
5688 /* ... or this is a truncation (t is narrower than op0),
5689 then we cannot pass through this narrowing. */
5692 /* ... or signedness changes for division or modulus,
5693 then we cannot pass through this conversion. */
5699 /* Pass the constant down and see if we can make a simplification. If
5700 we can, replace this expression with the inner simplification for
5701 possible later conversion to our or some other type. */
5706 code == MULT_EXPR
5708 strict_overflow_p))))
5713 /* If widening the type changes it from signed to unsigned, then we
5714 must avoid building ABS_EXPR itself as unsigned. */
5716 {
5720 {
5723 }
5725 }
5726 /* FALLTHROUGH */
5734 /* If widening the type changes the signedness, then we can't perform
5735 this optimization as that changes the result. */
5739 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5745 {
5752 }
5756 /* If the second operand is constant, this is a multiplication
5757 or floor division, by a power of two, so we can treat it that
5758 way unless the multiplier or divisor overflows. Signed
5759 left-shift overflow is implementation-defined rather than
5760 undefined in C90, so do not convert signed left shift into
5761 multiplication. */
5764 /* const_binop may not detect overflow correctly,
5765 so check for it explicitly here. */
5770 size_one_node,
5780 /* See if we can eliminate the operation on both sides. If we can, we
5781 can return a new PLUS or MINUS. If we can't, the only remaining
5782 cases where we can do anything are if the second operand is a
5783 constant. */
5789 /* If not multiplication, we can only do this if both operands
5790 are divisible by c. */
5793 {
5798 }
5800 /* If this was a subtraction, negate OP1 and set it to be an addition.
5801 This simplifies the logic below. */
5808 /* If either OP1 or C are negative, this optimization is not safe for
5809 some of the division and remainder types while for others we need
5810 to change the code. */
5812 {
5820 }
5822 /* If it's a multiply or a division/modulus operation of a multiple
5823 of our constant, do the operation and verify it doesn't overflow. */
5826 {
5829 /* We allow the constant to overflow with wrapping semantics. */
5833 }
5834 else
5837 /* If we have an unsigned type is not a sizetype, we cannot widen
5838 the operation since it will change the result if the original
5839 computation overflowed. */
5845 /* If we were able to eliminate our operation from the first side,
5846 apply our operation to the second side and reform the PLUS. */
5850 /* The last case is if we are a multiply. In that case, we can
5851 apply the distributive law to commute the multiply and addition
5852 if the multiplication of the constants doesn't overflow. */
5858 op1);
5863 /* We have a special case here if we are doing something like
5864 (C * 8) % 4 since we know that's zero. */
5871 /* ... fall through ... */
5875 /* If we can extract our operation from the LHS, do so and return a
5876 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5877 do something only if the second operand is a constant. */
5891 /* If these are the same operation types, we can associate them
5892 assuming no overflow. */
5899 /* If these operations "cancel" each other, we have the main
5900 optimizations of this pass, which occur when either constant is a
5901 multiple of the other, in which case we replace this with either an
5902 operation or CODE or TCODE.
5904 If we have an unsigned type that is not a sizetype, we cannot do
5905 this since it will change the result if the original computation
5906 overflowed. */
5913 {
5915 {
5922 }
5924 {
5931 }
5932 }
5937 }
5940 }
5941 \f
5942 /* Return a node which has the indicated constant VALUE (either 0 or
5943 1), and is of the indicated TYPE. */
5945 tree
5947 {
5952 else
5954 }
5957 /* Return true if expr looks like an ARRAY_REF and set base and
5958 offset to the appropriate trees. If there is no offset,
5959 offset is set to NULL_TREE. Base will be canonicalized to
5960 something you can get the element type from using
5961 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5962 in bytes to the base. */
5964 static bool
5966 {
5967 /* One canonical form is a PLUS_EXPR with the first
5968 argument being an ADDR_EXPR with a possible NOP_EXPR
5969 attached. */
5971 {
5974 /* Strip NOP_EXPRs here because the C frontends and/or
5975 folders present us (int *)&x.a + 4B possibly. */
5978 {
5982 else
5986 }
5987 }
5988 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5989 which we transform into an ADDR_EXPR with appropriate
5990 offset. For other arguments to the ADDR_EXPR we assume
5991 zero offset and as such do not care about the ADDR_EXPR
5992 type and strip possible nops from it. */
5994 {
5997 {
6002 }
6003 else
6004 {
6005 /* Handle array-to-pointer decay as &a. */
6008 else
6011 }
6013 }
6014 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
6017 {
6021 }
6024 }
6027 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6028 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6029 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6030 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6031 COND is the first argument to CODE; otherwise (as in the example
6032 given here), it is the second argument. TYPE is the type of the
6033 original expression. Return NULL_TREE if no simplification is
6034 possible. */
6036 static tree
6040 {
6047 /* This transformation is only worthwhile if we don't have to wrap
6048 arg in a SAVE_EXPR, and the operation can be simplified on at least
6049 one of the branches once its pushed inside the COND_EXPR. */
6054 {
6058 /* If this operand throws an expression, then it does not make
6059 sense to try to perform a logical or arithmetic operation
6060 involving it. */
6065 }
6066 else
6067 {
6072 }
6076 {
6080 else
6082 }
6084 {
6088 else
6090 }
6094 }
6096 \f
6097 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6099 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6100 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6101 ADDEND is the same as X.
6103 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6104 and finite. The problematic cases are when X is zero, and its mode
6105 has signed zeros. In the case of rounding towards -infinity,
6106 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6107 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6109 static bool
6111 {
6115 /* Don't allow the fold with -fsignaling-nans. */
6119 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6123 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6128 /* The mode has signed zeros, and we have to honor their sign.
6129 In this situation, there is only one case we can return true for.
6130 X - 0 is the same as X unless rounding towards -infinity is
6131 supported. */
6133 }
6135 /* Subroutine of fold() that checks comparisons of built-in math
6136 functions against real constants.
6138 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6139 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6140 is the type of the result and ARG0 and ARG1 are the operands of the
6141 comparison. ARG1 must be a TREE_REAL_CST.
6143 The function returns the constant folded tree if a simplification
6144 can be made, and NULL_TREE otherwise. */
6146 static tree
6149 {
6150 REAL_VALUE_TYPE c;
6153 {
6159 {
6160 /* sqrt(x) < y is always false, if y is negative. */
6164 /* sqrt(x) > y is always true, if y is negative and we
6165 don't care about NaNs, i.e. negative values of x. */
6169 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6172 }
6174 {
6175 REAL_VALUE_TYPE c2;
6181 {
6182 /* sqrt(x) > y is x == +Inf, when y is very large. */
6187 /* sqrt(x) > y is always false, when y is very large
6188 and we don't care about infinities. */
6190 }
6192 /* sqrt(x) > c is the same as x > c*c. */
6195 }
6197 {
6198 REAL_VALUE_TYPE c2;
6204 {
6205 /* sqrt(x) < y is always true, when y is a very large
6206 value and we don't care about NaNs or Infinities. */
6210 /* sqrt(x) < y is x != +Inf when y is very large and we
6211 don't care about NaNs. */
6216 /* sqrt(x) < y is x >= 0 when y is very large and we
6217 don't care about Infinities. */
6222 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6231 dconst0)),
6234 c2)));
6235 }
6237 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6242 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6245 {
6250 dconst0)),
6253 c2)));
6254 }
6255 }
6256 }
6259 }
6261 /* Subroutine of fold() that optimizes comparisons against Infinities,
6262 either +Inf or -Inf.
6264 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6265 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6266 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6268 The function returns the constant folded tree if a simplification
6269 can be made, and NULL_TREE otherwise. */
6271 static tree
6273 {
6275 REAL_VALUE_TYPE max;
6276 tree temp;
6281 /* For negative infinity swap the sense of the comparison. */
6287 {
6289 /* x > +Inf is always false, if with ignore sNANs. */
6295 /* x <= +Inf is always true, if we don't case about NaNs. */
6299 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6302 {
6305 }
6310 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6316 /* x < +Inf is always equal to x <= DBL_MAX. */
6322 /* x != +Inf is always equal to !(x > DBL_MAX). */
6334 }
6337 }
6339 /* Subroutine of fold() that optimizes comparisons of a division by
6340 a nonzero integer constant against an integer constant, i.e.
6341 X/C1 op C2.
6343 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6344 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6345 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6347 The function returns the constant folded tree if a simplification
6348 can be made, and NULL_TREE otherwise. */
6350 static tree
6352 {
6357 HOST_WIDE_INT hpart;
6362 /* We have to do this the hard way to detect unsigned overflow.
6363 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6374 {
6379 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6387 }
6389 {
6393 {
6412 }
6413 }
6414 else
6415 {
6416 /* A negative divisor reverses the relational operators. */
6422 {
6441 }
6442 }
6445 {
6466 {
6469 }
6474 {
6477 }
6482 {
6485 }
6490 {
6493 }
6498 }
6501 }
6504 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6505 equality/inequality test, then return a simplified form of the test
6506 using a sign testing. Otherwise return NULL. TYPE is the desired
6507 result type. */
6509 static tree
6511 tree result_type)
6512 {
6513 /* If this is testing a single bit, we can optimize the test. */
6517 {
6518 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6519 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6523 /* This is only a win if casting to a signed type is cheap,
6524 i.e. when arg00's type is not a partial mode. */
6527 {
6532 }
6533 }
6536 }
6538 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6539 equality/inequality test, then return a simplified form of
6540 the test using shifts and logical operations. Otherwise return
6541 NULL. TYPE is the desired result type. */
6543 tree
6545 tree result_type)
6546 {
6547 /* If this is testing a single bit, we can optimize the test. */
6551 {
6560 /* First, see if we can fold the single bit test into a sign-bit
6561 test. */
6563 result_type);
6567 /* Otherwise we have (A & C) != 0 where C is a single bit,
6568 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6569 Similarly for (A & C) == 0. */
6571 /* If INNER is a right shift of a constant and it plus BITNUM does
6572 not overflow, adjust BITNUM and INNER. */
6579 {
6582 }
6584 /* If we are going to be able to omit the AND below, we must do our
6585 operations as unsigned. If we must use the AND, we have a choice.
6586 Normally unsigned is faster, but for some machines signed is. */
6587 #ifdef LOAD_EXTEND_OP
6590 #else
6592 #endif
6608 /* Put the AND last so it can combine with more things. */
6611 /* Make sure to return the proper type. */
6615 }
6617 }
6619 /* Check whether we are allowed to reorder operands arg0 and arg1,
6620 such that the evaluation of arg1 occurs before arg0. */
6622 static bool
6624 {
6631 }
6633 /* Test whether it is preferable two swap two operands, ARG0 and
6634 ARG1, for example because ARG0 is an integer constant and ARG1
6635 isn't. If REORDER is true, only recommend swapping if we can
6636 evaluate the operands in reverse order. */
6638 bool
6640 {
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. */
6686 }
6688 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6689 ARG0 is extended to a wider type. */
6691 static tree
6693 {
6695 tree arg1_unw;
6704 #ifdef HAVE_canonicalize_funcptr_for_compare
6705 /* Disable this optimization if we're casting a function pointer
6706 type on targets that require function pointer canonicalization. */
6711 #endif
6718 /* If possible, express the comparison in the shorter mode. */
6734 /* If we are comparing with the integer that does not fit into the range
6735 of the shorter type, the result is known. */
6746 {
6773 }
6776 }
6778 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6779 ARG0 just the signedness is changed. */
6781 static tree
6784 {
6785 tree arg0_inner;
6796 #ifdef HAVE_canonicalize_funcptr_for_compare
6797 /* Disable this optimization if we're casting a function pointer
6798 type on targets that require function pointer canonicalization. */
6803 #endif
6823 else
6827 }
6829 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6830 step of the array. Reconstructs s and delta in the case of s * delta
6831 being an integer constant (and thus already folded).
6832 ADDR is the address. MULT is the multiplicative expression.
6833 If the function succeeds, the new address expression is returned. Otherwise
6834 NULL_TREE is returned. */
6836 static tree
6838 {
6842 tree itype;
6845 /* Canonicalize op1 into a possibly non-constant delta
6846 and an INTEGER_CST s. */
6848 {
6855 {
6858 }
6860 {
6863 }
6864 else
6866 }
6868 {
6871 }
6872 else
6873 {
6874 /* Simulate we are delta * 1. */
6877 }
6880 {
6882 {
6883 /* Remember if this was a multi-dimensional array. */
6896 {
6899 }
6900 else
6901 {
6902 /* Try if delta is a multiple of step. */
6907 }
6909 /* Only fold here if we can verify we do not overflow one
6910 dimension of a multi-dimensional array. */
6912 {
6913 tree tmp;
6929 }
6932 }
6933 else
6938 }
6940 /* We found the suitable array reference. So copy everything up to it,
6941 and replace the index. */
6948 {
6952 }
6960 }
6963 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6964 means A >= Y && A != MAX, but in this case we know that
6965 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6967 static tree
6969 {
6976 else
6985 {
6988 }
6990 {
6993 }
6994 else
7005 }
7007 /* Fold a sum or difference of at least one multiplication.
7008 Returns the folded tree or NULL if no simplification could be made. */
7010 static tree
7012 {
7016 /* (A * C) +- (B * C) -> (A+-B) * C.
7017 (A * C) +- A -> A * (C+-1).
7018 We are most concerned about the case where C is a constant,
7019 but other combinations show up during loop reduction. Since
7020 it is not difficult, try all four possibilities. */
7023 {
7026 }
7027 else
7028 {
7031 }
7033 {
7036 }
7037 else
7038 {
7041 }
7053 /* No identical multiplicands; see if we can find a common
7054 power-of-two factor in non-power-of-two multiplies. This
7055 can help in multi-dimensional array access. */
7058 {
7061 tree maybe_same;
7065 /* Move min of absolute values to int11. */
7068 {
7073 }
7074 else
7078 {
7086 }
7087 }
7097 }
7099 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7100 specified by EXPR into the buffer PTR of length LEN bytes.
7101 Return the number of bytes placed in the buffer, or zero
7102 upon failure. */
7104 static int
7106 {
7117 {
7121 else
7126 {
7133 else
7135 }
7136 else
7139 }
7141 }
7144 /* Subroutine of native_encode_expr. Encode the REAL_CST
7145 specified by EXPR into the buffer PTR of length LEN bytes.
7146 Return the number of bytes placed in the buffer, or zero
7147 upon failure. */
7149 static int
7151 {
7157 /* There are always 32 bits in each long, no matter the size of
7158 the hosts long. We handle floating point representations with
7159 up to 192 bits. */
7169 {
7174 {
7181 else
7183 }
7184 else
7187 }
7189 }
7191 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7192 specified by EXPR into the buffer PTR of length LEN bytes.
7193 Return the number of bytes placed in the buffer, or zero
7194 upon failure. */
7196 static int
7198 {
7200 tree part;
7211 }
7214 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7215 specified by EXPR into the buffer PTR of length LEN bytes.
7216 Return the number of bytes placed in the buffer, or zero
7217 upon failure. */
7219 static int
7221 {
7231 {
7233 {
7236 }
7237 else
7241 {
7244 }
7245 else
7246 {
7250 }
7252 }
7254 }
7257 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7258 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7259 buffer PTR of length LEN bytes. Return the number of bytes
7260 placed in the buffer, or zero upon failure. */
7262 static int
7264 {
7266 {
7281 }
7282 }
7285 /* Subroutine of native_interpret_expr. Interpret the contents of
7286 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7287 If the buffer cannot be interpreted, return NULL_TREE. */
7289 static tree
7291 {
7305 {
7308 {
7315 else
7317 }
7318 else
7324 else
7327 }
7330 }
7333 /* Subroutine of native_interpret_expr. Interpret the contents of
7334 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7335 If the buffer cannot be interpreted, return NULL_TREE. */
7337 static tree
7339 {
7344 /* There are always 32 bits in each long, no matter the size of
7345 the hosts long. We handle floating point representations with
7346 up to 192 bits. */
7347 REAL_VALUE_TYPE r;
7357 {
7360 {
7367 else
7369 }
7370 else
7375 }
7379 }
7382 /* Subroutine of native_interpret_expr. Interpret the contents of
7383 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7384 If the buffer cannot be interpreted, return NULL_TREE. */
7386 static tree
7388 {
7403 }
7406 /* Subroutine of native_interpret_expr. Interpret the contents of
7407 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7408 If the buffer cannot be interpreted, return NULL_TREE. */
7410 static tree
7412 {
7424 {
7429 }
7431 }
7434 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7435 the buffer PTR of length LEN as a constant of type TYPE. For
7436 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7437 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7438 return NULL_TREE. */
7440 static tree
7442 {
7444 {
7461 }
7462 }
7465 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7466 TYPE at compile-time. If we're unable to perform the conversion
7467 return NULL_TREE. */
7469 static tree
7471 {
7472 /* We support up to 512-bit values (for V8DFmode). */
7476 /* Check that the host and target are sane. */
7485 }
7488 /* Fold a unary expression of code CODE and type TYPE with operand
7489 OP0. Return the folded expression if folding is successful.
7490 Otherwise, return NULL_TREE. */
7492 tree
7494 {
7495 tree tem;
7496 tree arg0;
7504 {
7507 {
7508 /* Don't use STRIP_NOPS, because signedness of argument type
7509 matters. */
7511 }
7512 else
7513 {
7514 /* Strip any conversions that don't change the mode. This
7515 is safe for every expression, except for a comparison
7516 expression because its signedness is derived from its
7517 operands.
7519 Note that this is done as an internal manipulation within
7520 the constant folder, in order to find the simplest
7521 representation of the arguments so that their form can be
7522 studied. In any cases, the appropriate type conversions
7523 should be put back in the tree that will get out of the
7524 constant folder. */
7526 }
7527 }
7530 {
7535 {
7545 /* If this was a conversion, and all we did was to move into
7546 inside the COND_EXPR, bring it back out. But leave it if
7547 it is a conversion from integer to integer and the
7548 result precision is no wider than a word since such a
7549 conversion is cheap and may be optimized away by combine,
7550 while it couldn't if it were outside the COND_EXPR. Then return
7551 so we don't get into an infinite recursion loop taking the
7552 conversion out and then back in. */
7564 && (INTEGRAL_TYPE_P
7576 }
7578 {
7580 {
7584 }
7588 integer_one_node),
7590 integer_zero_node));
7591 }
7592 }
7595 {
7603 /* If we have (type) (a CMP b) and type is an integral type, return
7604 new expression involving the new type. */
7609 /* Handle cases of two conversions in a row. */
7612 {
7634 /* In addition to the cases of two conversions in a row
7635 handled below, if we are converting something to its own
7636 type via an object of identical or wider precision, neither
7637 conversion is needed. */
7644 /* Likewise, if the intermediate and final types are either both
7645 float or both integer, we don't need the middle conversion if
7646 it is wider than the final type and doesn't change the signedness
7647 (for integers). Avoid this if the final type is a pointer
7648 since then we sometimes need the inner conversion. Likewise if
7649 the outer has a precision not equal to the size of its mode. */
7658 && ! final_ptr
7662 /* If we have a sign-extension of a zero-extended value, we can
7663 replace that by a single zero-extension. */
7669 /* Two conversions in a row are not needed unless:
7670 - some conversion is floating-point (overstrict for now), or
7671 - some conversion is a vector (overstrict for now), or
7672 - the intermediate type is narrower than both initial and
7673 final, or
7674 - the intermediate type and innermost type differ in signedness,
7675 and the outermost type is wider than the intermediate, or
7676 - the initial type is a pointer type and the precisions of the
7677 intermediate and final types differ, or
7678 - the final type is a pointer type and the precisions of the
7679 initial and intermediate types differ.
7680 - the final type is a pointer type and the initial type not
7681 - the initial type is a pointer to an array and the final type
7682 not. */
7696 && ! (inside_ptr
7700 }
7702 /* Handle (T *)&A.B.C for A being of type T and B and C
7703 living at offset zero. This occurs frequently in
7704 C++ upcasting and then accessing the base. */
7708 {
7710 tree offset;
7716 /* If the reference was to a (constant) zero offset, we can use
7717 the address of the base if it has the same base type
7718 as the result type. */
7723 }
7728 /* Detect assigning a bitfield. */
7730 && DECL_BIT_FIELD
7732 {
7733 /* Don't leave an assignment inside a conversion
7734 unless assigning a bitfield. */
7736 /* First do the assignment, then return converted constant. */
7741 }
7743 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7744 constants (if x has signed type, the sign bit cannot be set
7745 in c). This folds extension into the BIT_AND_EXPR. */
7750 {
7760 <= HOST_BITS_PER_WIDE_INT
7762 {
7769 #ifdef LOAD_EXTEND_OP
7771 && !flag_syntax_only
7774 {
7778 }
7779 #endif
7780 }
7782 {
7788 }
7789 }
7791 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
7792 T2 being pointers to types of the same size. */
7797 {
7809 }
7811 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7812 of the same precision, and X is a integer type not narrower than
7813 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7820 {
7825 }
7848 /* Convert fabs((double)float) into (double)fabsf(float). */
7851 {
7856 targ0));
7857 }
7858 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7864 /* Strip sign ops from argument. */
7866 {
7870 }
7877 {
7882 }
7884 {
7889 }
7899 /* Convert ~ (-A) to A - 1. */
7903 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7910 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7927 /* The argument to invert_truthvalue must have Boolean type. */
7931 /* Note that the operand of this must be an int
7932 and its values must be 0 or 1.
7933 ("true" is a fixed value perhaps depending on the language,
7934 but we don't handle values other than 1 correctly yet.) */
7949 {
7957 }
7959 {
7963 }
7965 {
7969 {
7979 }
7980 }
7992 {
8000 }
8002 {
8006 }
8008 {
8012 {
8022 }
8023 }
8029 }
8031 /* Fold a binary expression of code CODE and type TYPE with operands
8032 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8033 Return the folded expression if folding is successful. Otherwise,
8034 return NULL_TREE. */
8036 static tree
8038 {
8045 else
8048 /* MIN (MAX (a, b), b) == b. */
8053 /* MIN (MAX (b, a), b) == b. */
8059 /* MIN (a, MAX (a, b)) == a. */
8065 /* MIN (a, MAX (b, a)) == a. */
8072 }
8074 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8075 by changing CODE to reduce the magnitude of constants involved in
8076 ARG0 of the comparison.
8077 Returns a canonicalized comparison tree if a simplification was
8078 possible, otherwise returns NULL_TREE.
8079 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8080 valid if signed overflow is undefined. */
8082 static tree
8086 {
8092 /* Match A +- CST code arg1 and CST code arg1. */
8099 /* Identify the constant in arg0 and its sign. */
8102 else
8106 /* Overflowed constants and zero will cause problems. */
8111 /* See if we can reduce the magnitude of the constant in
8112 arg0 by changing the comparison code. */
8114 {
8115 /* CST <= arg1 -> CST-1 < arg1. */
8118 /* -CST < arg1 -> -CST-1 <= arg1. */
8121 /* CST > arg1 -> CST-1 >= arg1. */
8124 /* -CST >= arg1 -> -CST-1 > arg1. */
8127 else
8129 /* arg1 code' CST' might be more canonical. */
8131 }
8132 else
8133 {
8134 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8138 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8142 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8146 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8150 else
8153 }
8155 /* Now build the constant reduced in magnitude. */
8161 /* If swapping might yield to a more canonical form, do so. */
8164 else
8166 }
8168 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8169 overflow further. Try to decrease the magnitude of constants involved
8170 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8171 and put sole constants at the second argument position.
8172 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8174 static tree
8177 {
8178 tree t;
8183 /* In principle pointers also have undefined overflow behavior,
8184 but that causes problems elsewhere. */
8189 /* Try canonicalization by simplifying arg0. */
8194 {
8198 }
8200 /* Try canonicalization by simplifying arg1 using the swapped
8201 comparison. */
8209 }
8211 /* Subroutine of fold_binary. This routine performs all of the
8212 transformations that are common to the equality/inequality
8213 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8214 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8215 fold_binary should call fold_binary. Fold a comparison with
8216 tree code CODE and type TYPE with operands OP0 and OP1. Return
8217 the folded comparison or NULL_TREE. */
8219 static tree
8221 {
8234 /* If one arg is a real or integer constant, put it last. */
8238 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8245 {
8249 tree lhs;
8256 /* If the constant operation overflowed this can be
8257 simplified as a comparison against INT_MAX/INT_MIN. */
8260 {
8264 /* Get the sign of the constant on the lhs if the
8265 operation were VARIABLE + CONST1. */
8269 /* The sign of the constant determines if we overflowed
8270 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8271 Canonicalize to the INT_MIN overflow by swapping the comparison
8272 if necessary. */
8276 /* We now can look at the canonicalized case
8277 VARIABLE + 1 CODE2 INT_MIN
8278 and decide on the result. */
8287 }
8292 {
8294 "when changing X +- C1 cmp C2 to "
8296 WARN_STRICT_OVERFLOW_COMPARISON);
8298 }
8299 }
8301 /* For comparisons of pointers we can decompose it to a compile time
8302 comparison of the base objects and the offsets into the object.
8303 This requires at least one operand being an ADDR_EXPR to do more
8304 than the operand_equal_p test below. */
8308 {
8315 /* Get base and offset for the access. Strip ADDR_EXPR for
8316 get_inner_reference, but put it back by stripping INDIRECT_REF
8317 off the base object if possible. */
8320 {
8326 else
8328 }
8332 {
8336 /* We have to make sure to have an indirect/non-indirect base1
8337 just the same as we did for base0. */
8343 }
8347 /* If we have equivalent bases we might be able to simplify. */
8350 {
8351 /* We can fold this expression to a constant if the non-constant
8352 offset parts are equal. */
8356 {
8358 {
8372 }
8373 }
8374 /* We can simplify the comparison to a comparison of the variable
8375 offset parts if the constant offset parts are equal.
8376 Be careful to use signed size type here because otherwise we
8377 mess with array offsets in the wrong way. This is possible
8378 because pointer arithmetic is restricted to retain within an
8379 object and overflow on pointer differences is undefined as of
8380 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8382 {
8383 tree signed_size_type_node;
8386 /* By converting to signed size type we cover middle-end pointer
8387 arithmetic which operates on unsigned pointer types of size
8388 type size and ARRAY_REF offsets which are properly sign or
8389 zero extended from their type in case it is narrower than
8390 size type. */
8393 else
8397 else
8401 }
8402 }
8403 }
8405 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8406 same object, then we can fold this to a comparison of the two offsets in
8407 signed size type. This is possible because pointer arithmetic is
8408 restricted to retain within an object and overflow on pointer differences
8409 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8411 We check flag_wrapv directly because pointers types are unsigned,
8412 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8413 normally what we want to avoid certain odd overflow cases, but
8414 not here. */
8416 && !flag_wrapv
8418 {
8424 {
8425 tree signed_size_type_node;
8428 /* By converting to signed size type we cover middle-end pointer
8429 arithmetic which operates on unsigned pointer types of size
8430 type size and ARRAY_REF offsets which are properly sign or
8431 zero extended from their type in case it is narrower than
8432 size type. */
8435 else
8439 else
8443 }
8444 }
8446 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8447 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8448 the resulting offset is smaller in absolute value than the
8449 original one. */
8457 {
8462 tree cst;
8464 "occur when combining constants around "
8467 /* Put the constant on the side where it doesn't overflow and is
8468 of lower absolute value than before. */
8474 {
8477 variable1,
8480 }
8487 {
8492 variable2);
8493 }
8494 }
8496 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8497 signed arithmetic case. That form is created by the compiler
8498 often enough for folding it to be of value. One example is in
8499 computing loop trip counts after Operator Strength Reduction. */
8505 {
8514 "eliminating multiplication in comparison "
8516 WARN_STRICT_OVERFLOW_COMPARISON);
8518 /* If const1 is negative we swap the sense of the comparison. */
8523 }
8530 {
8538 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8543 /* (-a) CMP (-b) -> b CMP a */
8550 {
8551 REAL_VALUE_TYPE cst;
8554 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8561 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8562 /* a CMP (-0) -> a CMP 0 */
8567 /* x != NaN is always true, other ops are always false. */
8570 {
8573 }
8575 /* Fold comparisons against infinity. */
8577 {
8581 }
8582 }
8584 /* If this is a comparison of a real constant with a PLUS_EXPR
8585 or a MINUS_EXPR of a real constant, we can convert it into a
8586 comparison with a revised real constant as long as no overflow
8587 occurs when unsafe_math_optimizations are enabled. */
8599 /* Likewise, we can simplify a comparison of a real constant with
8600 a MINUS_EXPR whose first operand is also a real constant, i.e.
8601 (c1 - x) < c2 becomes x > c1-c2. */
8612 /* Fold comparisons against built-in math functions. */
8614 && flag_unsafe_math_optimizations
8616 {
8620 {
8624 }
8625 }
8626 }
8628 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
8632 /* This optimization is invalid for ordered comparisons
8633 if CONST+INCR overflows or if foo+incr might overflow.
8634 This optimization is invalid for floating point due to rounding.
8635 For pointer types we assume overflow doesn't happen. */
8639 {
8643 {
8649 }
8650 else
8651 {
8657 }
8660 /* If VAROP is a reference to a bitfield, we must mask
8661 the constant by the width of the field. */
8666 {
8671 /* First check whether the comparison would come out
8672 always the same. If we don't do that we would
8673 change the meaning with the masking. */
8686 }
8689 }
8694 {
8695 /* If we are widening one operand of an integer comparison,
8696 see if the other operand is similarly being widened. Perhaps we
8697 can do the comparison in the narrower type. */
8702 /* Or if we are changing signedness. */
8706 }
8708 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8709 constant, we can simplify it. */
8714 {
8718 }
8720 /* Simplify comparison of something with itself. (For IEEE
8721 floating-point, we can only do some of these simplifications.) */
8723 {
8725 {
8740 /* For NE, we can only do this simplification if integer
8741 or we don't honor IEEE floating point NaNs. */
8745 /* ... fall through ... */
8751 }
8752 }
8754 /* If we are comparing an expression that just has comparisons
8755 of two integer values, arithmetic expressions of those comparisons,
8756 and constants, we can simplify it. There are only three cases
8757 to check: the two values can either be equal, the first can be
8758 greater, or the second can be greater. Fold the expression for
8759 those three values. Since each value must be 0 or 1, we have
8760 eight possibilities, each of which corresponds to the constant 0
8761 or 1 or one of the six possible comparisons.
8763 This handles common cases like (a > b) == 0 but also handles
8764 expressions like ((x > y) - (y > x)) > 0, which supposedly
8765 occur in macroized code. */
8768 {
8773 /* Don't handle degenerate cases here; they should already
8774 have been handled anyway. */
8783 {
8787 /* We can't just pass T to eval_subst in case cval1 or cval2
8788 was the same as ARG1. */
8790 tree high_result
8794 arg1);
8795 tree equal_result
8799 arg1);
8800 tree low_result
8804 arg1);
8806 /* All three of these results should be 0 or 1. Confirm they are.
8807 Then use those values to select the proper code to use. */
8812 {
8813 /* Make a 3-bit mask with the high-order bit being the
8814 value for `>', the next for '=', and the low for '<'. */
8818 {
8820 /* Always false. */
8841 /* Always true. */
8843 }
8848 }
8849 }
8850 }
8852 /* Fold a comparison of the address of COMPONENT_REFs with the same
8853 type and component to a comparison of the address of the base
8854 object. In short, &x->a OP &y->a to x OP y and
8855 &x->a OP &y.a to x OP &y */
8860 {
8864 {
8870 }
8871 }
8873 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8874 into a single range test. */
8882 {
8886 }
8888 /* Fold ~X op ~Y as Y op X. */
8895 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
8903 }
8906 /* Subroutine of fold_binary. Optimize complex multiplications of the
8907 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8908 argument EXPR represents the expression "z" of type TYPE. */
8910 static tree
8912 {
8917 {
8920 }
8922 {
8925 }
8926 else
8927 {
8931 }
8940 }
8943 /* Fold a binary expression of code CODE and type TYPE with operands
8944 OP0 and OP1. Return the folded expression if folding is
8945 successful. Otherwise, return NULL_TREE. */
8947 tree
8949 {
8964 /* Strip any conversions that don't change the mode. This is
8965 safe for every expression, except for a comparison expression
8966 because its signedness is derived from its operands. So, in
8967 the latter case, only strip conversions that don't change the
8968 signedness.
8970 Note that this is done as an internal manipulation within the
8971 constant folder, in order to find the simplest representation
8972 of the arguments so that their form can be studied. In any
8973 cases, the appropriate type conversions should be put back in
8974 the tree that will get out of the constant folder. */
8977 {
8980 }
8981 else
8982 {
8985 }
8987 /* Note that TREE_CONSTANT isn't enough: static var addresses are
8988 constant but we can't do arithmetic on them. */
8993 {
8998 else
9002 {
9006 }
9007 }
9009 /* If this is a commutative operation, and ARG0 is a constant, move it
9010 to ARG1 to reduce the number of tests below. */
9015 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9017 First check for cases where an arithmetic operation is applied to a
9018 compound, conditional, or comparison operation. Push the arithmetic
9019 operation inside the compound or conditional to see if any folding
9020 can then be done. Convert comparison to conditional for this purpose.
9021 The also optimizes non-constant cases that used to be done in
9022 expand_expr.
9024 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9025 one of the operands is a comparison and the other is a comparison, a
9026 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9027 code below would make the expression more complex. Change it to a
9028 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9029 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9041 {
9045 boolean_type_node,
9053 }
9057 {
9069 {
9075 }
9078 {
9084 }
9085 }
9088 {
9090 /* A + (-B) -> A - B */
9095 /* (-A) + B -> B - A */
9101 /* Convert ~A + 1 to -A. */
9107 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9108 same or one. */
9112 {
9116 }
9119 {
9123 /* ~X + X is -1. */
9127 {
9130 }
9132 /* X + ~X is -1. */
9136 {
9139 }
9141 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9142 with a constant, and the two constants have no bits in common,
9143 we should treat this as a BIT_IOR_EXPR since this may produce more
9144 simplifications. */
9152 {
9155 }
9157 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9158 (plus (plus (mult) (mult)) (foo)) so that we can
9159 take advantage of the factoring cases below. */
9166 {
9172 else
9194 parg1)));
9195 }
9197 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
9198 of the array. Loop optimizer sometimes produce this type of
9199 expressions. */
9201 {
9205 }
9207 {
9211 }
9212 }
9213 else
9214 {
9215 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9219 /* Likewise if the operands are reversed. */
9223 /* Convert X + -C into X - C. */
9226 {
9232 }
9234 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9235 to __complex__ ( x, y ). This is not the same for SNaNs or
9236 if signed zeros are involved. */
9240 {
9247 {
9251 {
9257 }
9259 {
9265 }
9266 }
9267 }
9275 /* Convert x+x into x*2.0. */
9281 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
9285 {
9290 {
9291 tree tree0;
9294 }
9295 }
9296 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
9300 {
9305 {
9306 tree tree0;
9309 }
9310 }
9311 }
9313 bit_rotate:
9314 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9315 is a rotate of A by C1 bits. */
9316 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9317 is a rotate of A by B bits. */
9318 {
9327 {
9346 {
9354 TYPE_PRECISION
9359 ? LROTATE_EXPR
9362 }
9364 {
9372 TYPE_PRECISION
9377 ? LROTATE_EXPR
9380 }
9381 }
9382 }
9384 associate:
9385 /* In most languages, can't associate operations on floats through
9386 parentheses. Rather than remember where the parentheses were, we
9387 don't associate floats at all, unless the user has specified
9388 -funsafe-math-optimizations. */
9391 {
9395 /* Split both trees into variables, constants, and literals. Then
9396 associate each group together, the constants with literals,
9397 then the result with variables. This increases the chances of
9398 literals being recombined later and of generating relocatable
9399 expressions for the sum of a constant and literal. */
9404 /* Only do something if we found more than two objects. Otherwise,
9405 nothing has changed and we risk infinite recursion. */
9410 {
9411 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9420 /* Preserve the MINUS_EXPR if the negative part of the literal is
9421 greater than the positive part. Otherwise, the multiplicative
9422 folding code (i.e extract_muldiv) may be fooled in case
9423 unsigned constants are subtracted, like in the following
9424 example: ((X*2 + 4) - 8U)/2. */
9426 {
9430 {
9434 }
9435 else
9436 {
9440 }
9441 }
9443 {
9448 else
9449 {
9455 }
9456 }
9461 }
9462 }
9467 /* A - (-B) -> A + B */
9470 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9478 /* Convert -A - 1 to ~A. */
9486 /* Convert -1 - A to ~A. */
9492 {
9498 /* Fold A - (A & B) into ~B & A. */
9501 {
9506 arg0);
9511 arg0);
9512 }
9514 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9515 any power of 2 minus 1. */
9520 {
9526 {
9530 }
9531 }
9532 }
9534 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9538 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9539 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9540 (-ARG1 + ARG0) reduces to -ARG1. */
9544 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9545 __complex__ ( x, -y ). This is not the same for SNaNs or if
9546 signed zeros are involved. */
9550 {
9557 {
9561 {
9563 arg1r ? arg1r
9568 }
9570 {
9574 arg1i ? arg1i
9577 }
9578 }
9579 }
9581 /* Fold &x - &x. This can happen from &x.foo - &x.
9582 This is unsafe for certain floats even in non-IEEE formats.
9583 In IEEE, it is unsafe because it does wrong for NaNs.
9584 Also note that operand_equal_p is always false if an operand
9585 is volatile. */
9591 /* A - B -> A + (-B) if B is easily negatable. */
9594 /* Avoid this transformation if B is a positive REAL_CST. */
9602 /* Try folding difference of addresses. */
9603 {
9604 HOST_WIDE_INT diff;
9610 }
9612 /* Fold &a[i] - &a[j] to i-j. */
9617 {
9622 {
9630 }
9631 }
9633 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9634 of the array. Loop optimizer sometimes produce this type of
9635 expressions. */
9637 {
9641 }
9649 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9650 same or one. */
9654 {
9658 }
9663 /* (-A) * (-B) -> A * B */
9674 {
9679 /* Transform x * -1 into -x. */
9682 /* Transform x * -C into -x * C if x is easily negatable. */
9691 /* (a * (1 << b)) is (a << b) */
9707 {
9710 "occur when simplifying "
9712 WARN_STRICT_OVERFLOW_MISC);
9714 }
9716 /* Optimize z * conj(z) for integer complex numbers. */
9723 }
9724 else
9725 {
9726 /* Maybe fold x * 0 to 0. The expressions aren't the same
9727 when x is NaN, since x * 0 is also NaN. Nor are they the
9728 same in modes with signed zeros, since multiplying a
9729 negative value by 0 gives -0, not +0. */
9734 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9739 /* Transform x * -1.0 into -x. */
9744 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9749 {
9755 }
9757 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9759 {
9762 {
9765 }
9766 }
9768 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9769 This is not the same for NaNs or if signed zeros are
9770 involved. */
9776 {
9788 }
9790 /* Optimize z * conj(z) for floating point complex numbers.
9791 Guarded by flag_unsafe_math_optimizations as non-finite
9792 imaginary components don't produce scalar results. */
9803 {
9807 /* Optimizations of root(...)*root(...). */
9809 {
9814 /* Optimize sqrt(x)*sqrt(x) as x. */
9820 /* Optimize root(x)*root(y) as root(x*y). */
9825 }
9827 /* Optimize expN(x)*expN(y) as expN(x+y). */
9829 {
9836 }
9838 /* Optimizations of pow(...)*pow(...). */
9842 {
9850 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9852 {
9857 arg01));
9859 }
9861 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9863 {
9868 arg));
9870 }
9871 }
9873 /* Optimize tan(x)*cos(x) as sin(x). */
9882 {
9888 }
9890 /* Optimize x*pow(x,c) as pow(x,c+1). */
9894 {
9901 {
9903 REAL_VALUE_TYPE c;
9912 }
9913 }
9915 /* Optimize pow(x,c)*x as pow(x,c+1). */
9919 {
9926 {
9928 REAL_VALUE_TYPE c;
9937 }
9938 }
9940 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9943 {
9947 {
9952 }
9953 }
9954 }
9955 }
9959 bit_ior:
9967 /* ~X | X is -1. */
9970 {
9973 }
9975 /* X | ~X is -1. */
9978 {
9981 }
9983 /* Canonicalize (X & C1) | C2. */
9987 {
9995 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10000 {
10004 }
10005 else
10006 {
10010 }
10012 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10017 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
10027 arg1);
10028 }
10030 /* (X & Y) | Y is (X, Y). */
10034 /* (X & Y) | X is (Y, X). */
10039 /* X | (X & Y) is (Y, X). */
10044 /* X | (Y & X) is (Y, X). */
10054 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10056 This results in more efficient code for machines without a NAND
10057 instruction. Combine will canonicalize to the first form
10058 which will allow use of NAND instructions provided by the
10059 backend if they exist. */
10062 {
10067 }
10069 /* See if this can be simplified into a rotate first. If that
10070 is unsuccessful continue in the association code. */
10081 /* ~X ^ X is -1. */
10084 {
10087 }
10089 /* X ^ ~X is -1. */
10092 {
10095 }
10097 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10098 with a constant, and the two constants have no bits in common,
10099 we should treat this as a BIT_IOR_EXPR since this may produce more
10100 simplifications. */
10108 {
10111 }
10113 /* (X | Y) ^ X -> Y & ~ X*/
10116 {
10119 arg1);
10123 }
10125 /* (Y | X) ^ X -> Y & ~ X*/
10128 {
10131 arg1);
10135 }
10137 /* X ^ (X | Y) -> Y & ~ X*/
10140 {
10143 arg0);
10147 }
10149 /* X ^ (Y | X) -> Y & ~ X*/
10152 {
10155 arg0);
10159 }
10161 /* Convert ~X ^ ~Y to X ^ Y. */
10168 /* Convert ~X ^ C to X ^ ~C. */
10175 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10182 /* Fold (X & Y) ^ Y as ~X & Y. */
10185 {
10190 }
10191 /* Fold (X & Y) ^ X as ~Y & X. */
10195 {
10200 }
10201 /* Fold X ^ (X & Y) as X & ~Y. */
10204 {
10209 }
10210 /* Fold X ^ (Y & X) as ~Y & X. */
10214 {
10219 }
10221 /* See if this can be simplified into a rotate first. If that
10222 is unsuccessful continue in the association code. */
10233 /* ~X & X is always zero. */
10238 /* X & ~X is always zero. */
10243 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10253 /* (X | Y) & Y is (X, Y). */
10257 /* (X | Y) & X is (Y, X). */
10262 /* X & (X | Y) is (Y, X). */
10267 /* X & (Y | X) is (Y, X). */
10273 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10277 {
10283 }
10284 /* Fold ~X & 1 as (X & 1) == 0. */
10287 {
10293 }
10295 /* Fold (X ^ Y) & Y as ~X & Y. */
10298 {
10303 }
10304 /* Fold (X ^ Y) & X as ~Y & X. */
10308 {
10313 }
10314 /* Fold X & (X ^ Y) as X & ~Y. */
10317 {
10322 }
10323 /* Fold X & (Y ^ X) as ~Y & X. */
10327 {
10332 }
10337 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10340 {
10341 unsigned int prec
10348 }
10350 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10352 This results in more efficient code for machines without a NOR
10353 instruction. Combine will canonicalize to the first form
10354 which will allow use of NOR instructions provided by the
10355 backend if they exist. */
10358 {
10363 }
10368 /* Don't touch a floating-point divide by zero unless the mode
10369 of the constant can represent infinity. */
10375 /* Optimize A / A to 1.0 if we don't care about
10376 NaNs or Infinities. Skip the transformation
10377 for non-real operands. */
10382 {
10386 }
10388 /* The complex version of the above A / A optimization. */
10391 {
10395 {
10397 /* omit_two_operands will call fold_convert for us. */
10399 }
10400 }
10402 /* (-A) / (-B) -> A / B */
10412 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
10417 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
10422 /* If ARG1 is a constant, we can convert this to a multiply by the
10423 reciprocal. This does not have the same rounding properties,
10424 so only do this if -funsafe-math-optimizations. We can actually
10425 always safely do it if ARG1 is a power of two, but it's hard to
10426 tell if it is or not in a portable manner. */
10428 {
10433 /* Find the reciprocal if optimizing and the result is exact. */
10435 {
10436 REAL_VALUE_TYPE r;
10439 {
10443 }
10444 }
10445 }
10446 /* Convert A/B/C to A/(B*C). */
10453 /* Convert A/(B/C) to (A/B)*C. */
10461 /* Convert C1/(X*C2) into (C1/C2)/X. */
10466 {
10472 }
10475 {
10479 /* Optimize sin(x)/cos(x) as tan(x). */
10485 {
10491 }
10493 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10499 {
10503 {
10508 }
10509 }
10511 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10512 NaNs or Infinities. */
10516 {
10523 {
10529 }
10530 }
10532 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10533 NaNs or Infinities. */
10537 {
10544 {
10548 {
10553 tmp);
10554 }
10555 }
10556 }
10558 /* Optimize pow(x,c)/x as pow(x,c-1). */
10562 {
10568 {
10570 REAL_VALUE_TYPE c;
10579 }
10580 }
10582 /* Optimize x/expN(y) into x*expN(-y). */
10584 {
10591 }
10593 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10597 {
10606 }
10607 }
10612 /* Simplify A / (B << N) where A and B are positive and B is
10613 a power of 2, to A >> (N + log2(B)). */
10618 {
10621 {
10628 WARN_STRICT_OVERFLOW_MISC);
10634 }
10635 }
10636 /* Fall thru */
10645 /* X / -1 is -X. */
10652 /* Convert -A / -B to A / B when the type is signed and overflow is
10653 undefined. */
10657 {
10660 "when distributing negation across "
10662 WARN_STRICT_OVERFLOW_MISC);
10665 }
10669 {
10672 "when distributing negation across "
10674 WARN_STRICT_OVERFLOW_MISC);
10677 }
10679 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10680 operation, EXACT_DIV_EXPR.
10682 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10683 At one time others generated faster code, it's not clear if they do
10684 after the last round to changes to the DIV code in expmed.c. */
10693 {
10697 WARN_STRICT_OVERFLOW_MISC);
10699 }
10707 /* X % 1 is always zero, but be sure to preserve any side
10708 effects in X. */
10712 /* X % 0, return X % 0 unchanged so that we can get the
10713 proper warnings and errors. */
10717 /* 0 % X is always zero, but be sure to preserve any side
10718 effects in X. Place this after checking for X == 0. */
10722 /* X % -1 is zero. */
10729 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10730 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10735 {
10737 /* Also optimize A % (C << N) where C is a power of 2,
10738 to A & ((C << N) - 1). */
10743 {
10748 "occur when simplifying "
10750 WARN_STRICT_OVERFLOW_MISC);
10754 }
10755 }
10757 /* X % -C is the same as X % C. */
10764 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10769 /* X % -Y is the same as X % Y. */
10780 {
10784 WARN_STRICT_OVERFLOW_MISC);
10786 }
10797 /* Optimize -1 >> x for arithmetic right shifts. */
10800 /* ... fall through ... */
10803 shift:
10809 /* Since negative shift count is not well-defined,
10810 don't try to compute it in the compiler. */
10814 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10819 {
10823 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10824 being well defined. */
10826 {
10831 else
10833 }
10837 }
10839 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10840 into x & ((unsigned)-1 >> c) for unsigned types. */
10848 {
10851 tree lshift;
10852 tree arg00;
10855 {
10862 }
10863 }
10865 /* Rewrite an LROTATE_EXPR by a constant into an
10866 RROTATE_EXPR by a new constant. */
10868 {
10873 }
10875 /* If we have a rotate of a bit operation with the rotate count and
10876 the second operand of the bit operation both constant,
10877 permute the two operations. */
10889 /* Two consecutive rotates adding up to the width of the mode can
10890 be ignored. */
10927 /* Note that the operands of this must be ints
10928 and their values must be 0 or 1.
10929 ("true" is a fixed value perhaps depending on the language.) */
10930 /* If first arg is constant zero, return it. */
10934 /* If either arg is constant true, drop it. */
10938 /* Preserve sequence points. */
10941 /* If second arg is constant zero, result is zero, but first arg
10942 must be evaluated. */
10945 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10946 case will be handled here. */
10950 /* !X && X is always false. */
10954 /* X && !X is always false. */
10959 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10960 means A >= Y && A != MAX, but in this case we know that
10961 A < X <= MAX. */
10965 {
10973 }
10975 truth_andor:
10976 /* We only do these simplifications if we are optimizing. */
10980 /* Check for things like (A || B) && (A || C). We can convert this
10981 to A || (B && C). Note that either operator can be any of the four
10982 truth and/or operations and the transformation will still be
10983 valid. Also note that we only care about order for the
10984 ANDIF and ORIF operators. If B contains side effects, this
10985 might change the truth-value of A. */
10992 {
11012 /* This case if tricky because we must either have commutative
11013 operators or else A10 must not have side-effects. */
11019 a01);
11020 }
11022 /* See if we can build a range comparison. */
11026 /* Check for the possibility of merging component references. If our
11027 lhs is another similar operation, try to merge its rhs with our
11028 rhs. Then try to merge our lhs and rhs. */
11040 /* Note that the operands of this must be ints
11041 and their values must be 0 or true.
11042 ("true" is a fixed value perhaps depending on the language.) */
11043 /* If first arg is constant true, return it. */
11047 /* If either arg is constant zero, drop it. */
11051 /* Preserve sequence points. */
11054 /* If second arg is constant true, result is true, but we must
11055 evaluate first arg. */
11058 /* Likewise for first arg, but note this only occurs here for
11059 TRUTH_OR_EXPR. */
11063 /* !X || X is always true. */
11067 /* X || !X is always true. */
11075 /* If the second arg is constant zero, drop it. */
11078 /* If the second arg is constant true, this is a logical inversion. */
11080 {
11081 /* Only call invert_truthvalue if operand is a truth value. */
11084 else
11087 }
11088 /* Identical arguments cancel to zero. */
11092 /* !X ^ X is always true. */
11097 /* X ^ !X is always true. */
11110 /* bool_var != 0 becomes bool_var. */
11115 /* bool_var == 1 becomes bool_var. */
11120 /* bool_var != 1 becomes !bool_var. */
11125 /* bool_var == 0 becomes !bool_var. */
11130 /* If this is an equality comparison of the address of a non-weak
11131 object against zero, then we know the result. */
11138 /* If this is an equality comparison of the address of two non-weak,
11139 unaliased symbols neither of which are extern (since we do not
11140 have access to attributes for externs), then we know the result. */
11153 {
11154 /* We know that we're looking at the address of two
11155 non-weak, unaliased, static _DECL nodes.
11157 It is both wasteful and incorrect to call operand_equal_p
11158 to compare the two ADDR_EXPR nodes. It is wasteful in that
11159 all we need to do is test pointer equality for the arguments
11160 to the two ADDR_EXPR nodes. It is incorrect to use
11161 operand_equal_p as that function is NOT equivalent to a
11162 C equality test. It can in fact return false for two
11163 objects which would test as equal using the C equality
11164 operator. */
11168 type);
11169 }
11171 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
11172 a MINUS_EXPR of a constant, we can convert it into a comparison with
11173 a revised constant as long as no overflow occurs. */
11185 /* Similarly for a NEGATE_EXPR. */
11193 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11202 /* If we have X - Y == 0, we can convert that to X == Y and similarly
11203 for !=. Don't do this for ordered comparisons due to overflow. */
11209 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11214 /* If this is an EQ or NE comparison with zero and ARG0 is
11215 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11216 two operations, but the latter can be done in one less insn
11217 on machines that have only two-operand insns or on which a
11218 constant cannot be the first operand. */
11221 {
11226 return
11232 integer_one_node)),
11233 arg1);
11236 return
11242 integer_one_node)),
11243 arg1);
11244 }
11246 /* If this is an NE or EQ comparison of zero against the result of a
11247 signed MOD operation whose second operand is a power of 2, make
11248 the MOD operation unsigned since it is simpler and equivalent. */
11256 {
11266 }
11268 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11269 C1 is a valid shift constant, and C2 is a power of two, i.e.
11270 a single bit. */
11274 == INTEGER_CST
11277 {
11282 /* Check for a valid shift count. */
11285 {
11289 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11290 can be rewritten as (X & (C2 << C1)) != 0. */
11292 {
11296 }
11297 /* Otherwise, for signed (arithmetic) shifts,
11298 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11299 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11303 /* Otherwise, of unsigned (logical) shifts,
11304 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11305 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11306 else
11310 arg000);
11311 }
11312 }
11314 /* If this is an NE comparison of zero with an AND of one, remove the
11315 comparison since the AND will give the correct value. */
11322 /* If we have (A & C) == C where C is a power of 2, convert this into
11323 (A & C) != 0. Similarly for NE_EXPR. */
11329 integer_zero_node));
11331 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11332 bit, then fold the expression into A < 0 or A >= 0. */
11337 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11338 Similarly for NE_EXPR. */
11342 {
11351 }
11353 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11354 Similarly for NE_EXPR. */
11358 {
11365 }
11367 /* If this is a comparison of a field, we may be able to simplify it. */
11370 /* Handle the constant case even without -O
11371 to make sure the warnings are given. */
11373 {
11377 }
11379 /* Optimize comparisons of strlen vs zero to a compare of the
11380 first character of the string vs zero. To wit,
11381 strlen(ptr) == 0 => *ptr == 0
11382 strlen(ptr) != 0 => *ptr != 0
11383 Other cases should reduce to one of these two (or a constant)
11384 due to the return value of strlen being unsigned. */
11387 {
11389 tree arglist;
11397 {
11401 }
11402 }
11404 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11405 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11409 {
11416 {
11418 {
11421 }
11424 }
11425 }
11427 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
11433 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
11438 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
11445 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
11453 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11454 (X & C) == 0 when C is a single bit. */
11459 {
11465 }
11467 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11468 constant C is a power of two, i.e. a single bit. */
11475 {
11479 }
11481 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11482 when is C is a power of two, i.e. a single bit. */
11489 {
11495 }
11499 {
11502 }
11504 /* Fold -X op -Y as X op Y, where op is eq/ne. */
11511 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11514 {
11526 arg01),
11534 arg01),
11542 arg00),
11550 arg00),
11552 }
11556 {
11563 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11564 operand_equal_p guarantees no side-effects so we don't need
11565 to use omit_one_operand on Z. */
11575 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11582 arg10);
11583 }
11594 /* Transform comparisons of the form X +- C CMP X. */
11601 {
11608 else
11611 /* (X - c) > X becomes false. */
11615 {
11619 "occur when assuming that (X - c) > X "
11621 WARN_STRICT_OVERFLOW_ALL);
11623 }
11625 /* Likewise (X + c) < X becomes false. */
11629 {
11633 "occur when assuming that "
11635 WARN_STRICT_OVERFLOW_ALL);
11637 }
11639 /* Convert (X - c) <= X to true. */
11644 {
11648 "occur when assuming that "
11650 WARN_STRICT_OVERFLOW_ALL);
11652 }
11654 /* Convert (X + c) >= X to true. */
11659 {
11663 "occur when assuming that "
11665 WARN_STRICT_OVERFLOW_ALL);
11667 }
11670 {
11671 /* Convert X + c > X and X - c < X to true for integers. */
11675 {
11678 "not occur when assuming that "
11680 WARN_STRICT_OVERFLOW_ALL);
11682 }
11687 {
11690 "not occur when assuming that "
11692 WARN_STRICT_OVERFLOW_ALL);
11694 }
11696 /* Convert X + c <= X and X - c >= X to false for integers. */
11700 {
11703 "not occur when assuming that "
11705 WARN_STRICT_OVERFLOW_ALL);
11707 }
11712 {
11715 "not occur when assuming that "
11717 WARN_STRICT_OVERFLOW_ALL);
11719 }
11720 }
11721 }
11723 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11724 This transformation affects the cases which are handled in later
11725 optimizations involving comparisons with non-negative constants. */
11729 {
11731 {
11736 }
11738 {
11743 }
11744 }
11746 /* Comparisons with the highest or lowest possible integer of
11747 the specified precision will have known values. */
11748 {
11756 {
11757 HOST_WIDE_INT signed_max_hi;
11762 {
11769 {
11773 }
11774 else
11775 {
11779 }
11780 }
11781 else
11782 {
11791 {
11794 }
11795 else
11796 {
11799 }
11800 }
11805 {
11818 /* The GE_EXPR and LT_EXPR cases above are not normally
11819 reached because of previous transformations. */
11823 }
11825 == max_hi
11828 {
11839 }
11841 == min_hi
11844 {
11859 }
11861 == min_hi
11864 {
11873 }
11878 /* We will flip the signedness of the comparison operator
11879 associated with the mode of arg1, so the sign bit is
11880 specified by this mode. Check that arg1 is the signed
11881 max associated with this sign bit. */
11883 /* signed_type does not work on pointer types. */
11885 {
11886 /* The following case also applies to X < signed_max+1
11887 and X >= signed_max+1 because previous transformations. */
11889 {
11896 }
11897 }
11898 }
11899 }
11901 /* If we are comparing an ABS_EXPR with a constant, we can
11902 convert all the cases into explicit comparisons, but they may
11903 well not be faster than doing the ABS and one comparison.
11904 But ABS (X) <= C is a range comparison, which becomes a subtraction
11905 and a comparison, and is probably faster. */
11919 /* Convert ABS_EXPR<x> >= 0 to true. */
11926 {
11929 "when simplifying comparison of "
11931 WARN_STRICT_OVERFLOW_CONDITIONAL);
11933 }
11935 /* Convert ABS_EXPR<x> < 0 to false. */
11940 {
11943 "when simplifying comparison of "
11945 WARN_STRICT_OVERFLOW_CONDITIONAL);
11947 }
11949 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11950 and similarly for >= into !=. */
11966 return
11985 {
11989 }
11991 /* If the first operand is NaN, the result is constant. */
11995 {
11997 ? integer_zero_node
12000 }
12002 /* If the second operand is NaN, the result is constant. */
12006 {
12008 ? integer_zero_node
12011 }
12013 /* Simplify unordered comparison of something with itself. */
12019 && !flag_trapping_math
12023 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12024 {
12035 }
12040 /* When pedantic, a compound expression can be neither an lvalue
12041 nor an integer constant expression. */
12044 /* Don't let (0, 0) be null pointer constant. */
12058 /* An ASSERT_EXPR should never be passed to fold_binary. */
12064 }
12066 /* Callback for walk_tree, looking for LABEL_EXPR.
12067 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
12068 Do not check the sub-tree of GOTO_EXPR. */
12070 static tree
12074 {
12076 {
12081 /* no break */
12084 }
12085 }
12087 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
12088 accessible from outside the sub-tree. Returns NULL_TREE if no
12089 addressable label is found. */
12091 static bool
12093 {
12095 }
12097 /* Fold a ternary expression of code CODE and type TYPE with operands
12098 OP0, OP1, and OP2. Return the folded expression if folding is
12099 successful. Otherwise, return NULL_TREE. */
12101 tree
12103 {
12104 tree tem;
12111 /* Strip any conversions that don't change the mode. This is safe
12112 for every expression, except for a comparison expression because
12113 its signedness is derived from its operands. So, in the latter
12114 case, only strip conversions that don't change the signedness.
12116 Note that this is done as an internal manipulation within the
12117 constant folder, in order to find the simplest representation of
12118 the arguments so that their form can be studied. In any cases,
12119 the appropriate type conversions should be put back in the tree
12120 that will get out of the constant folder. */
12122 {
12125 }
12128 {
12131 }
12134 {
12138 {
12144 }
12148 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12149 so all simple results must be passed through pedantic_non_lvalue. */
12151 {
12154 /* Only optimize constant conditions when the selected branch
12155 has the same type as the COND_EXPR. This avoids optimizing
12156 away "c ? x : throw", where the throw has a void type.
12157 Avoid throwing away that operand which contains label. */
12164 }
12168 /* If we have A op B ? A : C, we may be able to convert this to a
12169 simpler expression, depending on the operation and the values
12170 of B and C. Signed zeros prevent all of these transformations,
12171 for reasons given above each one.
12173 Also try swapping the arguments and inverting the conditional. */
12178 {
12182 }
12186 op2,
12189 {
12192 {
12196 }
12197 }
12199 /* If the second operand is simpler than the third, swap them
12200 since that produces better jump optimization results. */
12203 {
12204 /* See if this can be inverted. If it can't, possibly because
12205 it was a floating-point inequality comparison, don't do
12206 anything. */
12210 }
12212 /* Convert A ? 1 : 0 to simply A. */
12215 /* If we try to convert OP0 to our type, the
12216 call to fold will try to move the conversion inside
12217 a COND, which will recurse. In that case, the COND_EXPR
12218 is probably the best choice, so leave it alone. */
12222 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12223 over COND_EXPR in cases such as floating point comparisons. */
12230 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12235 {
12236 /* sign_bit_p only checks ARG1 bits within A's precision.
12237 If <sign bit of A> has wider type than A, bits outside
12238 of A's precision in <sign bit of A> need to be checked.
12239 If they are all 0, this optimization needs to be done
12240 in unsigned A's type, if they are all 1 in signed A's type,
12241 otherwise this can't be done. */
12246 {
12248 HOST_WIDE_INT mask_hi;
12250 tree tem_type;
12258 {
12262 }
12263 else
12264 {
12268 }
12270 {
12274 }
12275 else
12281 {
12284 }
12287 {
12290 }
12291 else
12293 }
12300 arg1)));
12301 }
12303 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12304 already handled above. */
12309 {
12318 }
12320 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12321 is probably obsolete because the first operand should be a
12322 truth value (that's why we have the two cases above), but let's
12323 leave it in until we can confirm this for all front-ends. */
12334 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12340 arg1);
12342 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12346 {
12347 /* Only perform transformation if ARG0 is easily inverted. */
12352 arg1);
12353 }
12355 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
12359 {
12360 /* Only perform transformation if ARG0 is easily inverted. */
12365 op2);
12366 }
12368 /* Convert A ? 1 : B into A || B if A and B are truth values. */
12374 op2);
12379 /* Check for a built-in function. */
12391 {
12400 {
12406 else
12408 }
12409 }
12415 }
12417 /* Perform constant folding and related simplification of EXPR.
12418 The related simplifications include x*1 => x, x*0 => 0, etc.,
12419 and application of the associative law.
12420 NOP_EXPR conversions may be removed freely (as long as we
12421 are careful not to change the type of the overall expression).
12422 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12423 but we can constant-fold them if they have constant operands. */
12425 #ifdef ENABLE_FOLD_CHECKING
12426 # define fold(x) fold_1 (x)
12428 static
12429 #endif
12430 tree
12432 {
12436 tree tem;
12438 /* Return right away if a constant. */
12444 {
12449 {
12467 }
12468 }
12471 {
12478 }
12480 #ifdef ENABLE_FOLD_CHECKING
12481 #undef fold
12487 /* When --enable-checking=fold, compute a digest of expr before
12488 and after actual fold call to see if fold did not accidentally
12489 change original expr. */
12491 tree
12493 {
12494 tree ret;
12497 htab_t ht;
12516 }
12518 void
12520 {
12523 htab_t ht;
12533 }
12535 static void
12537 {
12539 }
12541 static void
12543 {
12549 recursive_label:
12563 {
12564 /* Allow DECL_ASSEMBLER_NAME to be modified. */
12568 }
12573 {
12574 /* Allow these fields to be modified. */
12581 {
12584 }
12585 }
12593 {
12596 {
12610 }
12614 {
12627 }
12643 {
12649 }
12654 {
12658 }
12669 {
12672 }
12682 }
12683 }
12685 #endif
12687 /* Fold a unary tree expression with code CODE of type TYPE with an
12688 operand OP0. Return a folded expression if successful. Otherwise,
12689 return a tree expression with code CODE of type TYPE with an
12690 operand OP0. */
12692 tree
12694 {
12695 tree tem;
12696 #ifdef ENABLE_FOLD_CHECKING
12699 htab_t ht;
12706 #endif
12712 #ifdef ENABLE_FOLD_CHECKING
12720 #endif
12722 }
12724 /* Fold a binary tree expression with code CODE of type TYPE with
12725 operands OP0 and OP1. Return a folded expression if successful.
12726 Otherwise, return a tree expression with code CODE of type TYPE
12727 with operands OP0 and OP1. */
12729 tree
12731 MEM_STAT_DECL)
12732 {
12733 tree tem;
12734 #ifdef ENABLE_FOLD_CHECKING
12740 htab_t ht;
12752 #endif
12758 #ifdef ENABLE_FOLD_CHECKING
12774 #endif
12776 }
12778 /* Fold a ternary tree expression with code CODE of type TYPE with
12779 operands OP0, OP1, and OP2. Return a folded expression if
12780 successful. Otherwise, return a tree expression with code CODE of
12781 type TYPE with operands OP0, OP1, and OP2. */
12783 tree
12785 MEM_STAT_DECL)
12786 {
12787 tree tem;
12788 #ifdef ENABLE_FOLD_CHECKING
12796 htab_t ht;
12813 #endif
12819 #ifdef ENABLE_FOLD_CHECKING
12843 #endif
12845 }
12847 /* Perform constant folding and related simplification of initializer
12848 expression EXPR. These behave identically to "fold_buildN" but ignore
12849 potential run-time traps and exceptions that fold must preserve. */
12851 #define START_FOLD_INIT \
12852 int saved_signaling_nans = flag_signaling_nans;\
12853 int saved_trapping_math = flag_trapping_math;\
12854 int saved_rounding_math = flag_rounding_math;\
12855 int saved_trapv = flag_trapv;\
12856 int saved_folding_initializer = folding_initializer;\
12857 flag_signaling_nans = 0;\
12858 flag_trapping_math = 0;\
12859 flag_rounding_math = 0;\
12860 flag_trapv = 0;\
12861 folding_initializer = 1;
12863 #define END_FOLD_INIT \
12864 flag_signaling_nans = saved_signaling_nans;\
12865 flag_trapping_math = saved_trapping_math;\
12866 flag_rounding_math = saved_rounding_math;\
12867 flag_trapv = saved_trapv;\
12868 folding_initializer = saved_folding_initializer;
12870 tree
12872 {
12873 tree result;
12874 START_FOLD_INIT;
12878 END_FOLD_INIT;
12880 }
12882 tree
12884 {
12885 tree result;
12886 START_FOLD_INIT;
12890 END_FOLD_INIT;
12892 }
12894 tree
12896 tree op2)
12897 {
12898 tree result;
12899 START_FOLD_INIT;
12903 END_FOLD_INIT;
12905 }
12907 #undef START_FOLD_INIT
12908 #undef END_FOLD_INIT
12910 /* Determine if first argument is a multiple of second argument. Return 0 if
12911 it is not, or we cannot easily determined it to be.
12913 An example of the sort of thing we care about (at this point; this routine
12914 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12915 fold cases do now) is discovering that
12917 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12919 is a multiple of
12921 SAVE_EXPR (J * 8)
12923 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12925 This code also handles discovering that
12927 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12929 is a multiple of 8 so we don't have to worry about dealing with a
12930 possible remainder.
12932 Note that we *look* inside a SAVE_EXPR only to determine how it was
12933 calculated; it is not safe for fold to do much of anything else with the
12934 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12935 at run time. For example, the latter example above *cannot* be implemented
12936 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12937 evaluation time of the original SAVE_EXPR is not necessarily the same at
12938 the time the new expression is evaluated. The only optimization of this
12939 sort that would be valid is changing
12941 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12943 divided by 8 to
12945 SAVE_EXPR (I) * SAVE_EXPR (J)
12947 (where the same SAVE_EXPR (J) is used in the original and the
12948 transformed version). */
12950 static int
12952 {
12960 {
12962 /* Bitwise and provides a power of two multiple. If the mask is
12963 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12966 /* FALLTHRU */
12979 {
12983 /* const_binop may not detect overflow correctly,
12984 so check for it explicitly here. */
12990 size_one_node,
12994 }
12998 /* Can't handle conversions from non-integral or wider integral type. */
13004 /* .. fall through ... */
13020 }
13021 }
13023 /* Return true if `t' is known to be non-negative. If the return
13024 value is based on the assumption that signed overflow is undefined,
13025 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13026 *STRICT_OVERFLOW_P. */
13028 bool
13030 {
13038 {
13040 /* Query VRP to see if it has recorded any information about
13041 the range of this object. */
13045 /* We can't return 1 if flag_wrapv is set because
13046 ABS_EXPR<INT_MIN> = INT_MIN. */
13050 {
13053 }
13065 strict_overflow_p)
13067 strict_overflow_p));
13069 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13070 both unsigned and at least 2 bits shorter than the result. */
13074 {
13079 {
13083 }
13084 }
13089 {
13090 /* x * x for floating point x is always non-negative. */
13094 strict_overflow_p)
13096 strict_overflow_p));
13097 }
13099 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13100 both unsigned and their total bits is shorter than the result. */
13104 {
13111 }
13117 strict_overflow_p)
13119 strict_overflow_p));
13130 strict_overflow_p)
13132 strict_overflow_p));
13142 strict_overflow_p);
13148 strict_overflow_p);
13152 strict_overflow_p);
13156 strict_overflow_p)
13158 strict_overflow_p));
13161 {
13166 {
13169 strict_overflow_p);
13171 {
13175 strict_overflow_p);
13176 }
13177 }
13179 {
13182 strict_overflow_p);
13186 }
13187 }
13191 {
13195 /* If the initializer is non-void, then it's a normal expression
13196 that will be assigned to the slot. */
13200 /* Otherwise, the initializer sets the slot in some way. One common
13201 way is an assignment statement at the end of the initializer. */
13203 {
13211 else
13213 }
13218 strict_overflow_p);
13221 }
13224 {
13229 {
13247 /* Always true. */
13251 /* sqrt(-0.0) is -0.0. */
13255 strict_overflow_p);
13284 /* True if the 1st argument is nonnegative. */
13286 strict_overflow_p);
13289 /* True if the 1st OR 2nd arguments are nonnegative. */
13291 strict_overflow_p)
13292 || (tree_expr_nonnegative_warnv_p
13294 strict_overflow_p)));
13297 /* True if the 1st AND 2nd arguments are nonnegative. */
13299 strict_overflow_p)
13300 && (tree_expr_nonnegative_warnv_p
13302 strict_overflow_p)));
13305 /* True if the 2nd argument is nonnegative. */
13308 strict_overflow_p));
13311 /* True if the 1st argument is nonnegative or the second
13312 argument is an even integer. */
13314 {
13318 }
13320 strict_overflow_p);
13323 /* True if the 1st argument is nonnegative or the second
13324 argument is an even integer valued real. */
13326 {
13327 REAL_VALUE_TYPE c;
13328 HOST_WIDE_INT n;
13333 {
13334 REAL_VALUE_TYPE cint;
13339 }
13340 }
13342 strict_overflow_p);
13346 }
13347 }
13349 /* ... fall through ... */
13353 /* Truth values evaluate to 0 or 1, which is nonnegative. */
13355 }
13357 /* We don't know sign of `t', so be conservative and return false. */
13359 }
13361 /* Return true if `t' is known to be non-negative. Handle warnings
13362 about undefined signed overflow. */
13364 bool
13366 {
13373 "determining that expression is always "
13375 WARN_STRICT_OVERFLOW_MISC);
13377 }
13379 /* Return true when T is an address and is known to be nonzero.
13380 For floating point we further ensure that T is not denormal.
13381 Similar logic is present in nonzero_address in rtlanal.h.
13383 If the return value is based on the assumption that signed overflow
13384 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13385 change *STRICT_OVERFLOW_P. */
13387 bool
13389 {
13393 /* Doing something useful for floating point would need more work. */
13398 {
13400 /* Query VRP to see if it has recorded any information about
13401 the range of this object. */
13406 strict_overflow_p);
13413 {
13414 /* With the presence of negative values it is hard
13415 to say something. */
13422 /* One of operands must be positive and the other non-negative. */
13423 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13424 overflows, on a twos-complement machine the sum of two
13425 nonnegative numbers can never be zero. */
13427 strict_overflow_p)
13429 strict_overflow_p));
13430 }
13435 {
13437 strict_overflow_p)
13439 strict_overflow_p))
13440 {
13443 }
13444 }
13448 {
13454 strict_overflow_p));
13455 }
13459 {
13465 /* Weak declarations may link to NULL. */
13469 /* Constants are never weak. */
13474 }
13482 {
13486 }
13495 {
13498 }
13505 {
13509 /* When both operands are nonzero, then MAX must be too. */
13511 strict_overflow_p))
13514 /* MAX where operand 0 is positive is positive. */
13516 strict_overflow_p);
13517 }
13518 /* MAX where operand 1 is positive is positive. */
13523 {
13527 }
13535 strict_overflow_p);
13540 strict_overflow_p);
13544 strict_overflow_p)
13546 strict_overflow_p));
13553 }
13555 }
13557 /* Return true when T is an address and is known to be nonzero.
13558 Handle warnings about undefined signed overflow. */
13560 bool
13562 {
13569 "determining that expression is always "
13571 WARN_STRICT_OVERFLOW_MISC);
13573 }
13575 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13576 attempt to fold the expression to a constant without modifying TYPE,
13577 OP0 or OP1.
13579 If the expression could be simplified to a constant, then return
13580 the constant. If the expression would not be simplified to a
13581 constant, then return NULL_TREE. */
13583 tree
13585 {
13588 }
13590 /* Given the components of a unary expression CODE, TYPE and OP0,
13591 attempt to fold the expression to a constant without modifying
13592 TYPE or OP0.
13594 If the expression could be simplified to a constant, then return
13595 the constant. If the expression would not be simplified to a
13596 constant, then return NULL_TREE. */
13598 tree
13600 {
13603 }
13605 /* If EXP represents referencing an element in a constant string
13606 (either via pointer arithmetic or array indexing), return the
13607 tree representing the value accessed, otherwise return NULL. */
13609 tree
13611 {
13615 {
13617 tree index;
13618 tree string;
13622 else
13623 {
13627 /* Optimize the special-case of a zero lower bound.
13629 We convert the low_bound to sizetype to avoid some problems
13630 with constant folding. (E.g. suppose the lower bound is 1,
13631 and its mode is QI. Without the conversion,l (ARRAY
13632 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13633 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
13638 }
13652 }
13654 }
13656 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13657 an integer constant or real constant.
13659 TYPE is the type of the result. */
13661 static tree
13663 {
13667 {
13669 {
13671 HOST_WIDE_INT high;
13679 }
13687 }
13690 }
13692 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13693 an integer constant or real constant.
13695 TYPE is the type of the result. */
13697 tree
13699 {
13703 {
13705 /* If the value is unsigned, then the absolute value is
13706 the same as the ordinary value. */
13709 /* Similarly, if the value is non-negative. */
13712 /* If the value is negative, then the absolute value is
13713 its negation. */
13714 else
13715 {
13717 HOST_WIDE_INT high;
13723 }
13729 else
13735 }
13738 }
13740 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13741 constant. TYPE is the type of the result. */
13743 static tree
13745 {
13755 }
13757 /* Given CODE, a relational operator, the target type, TYPE and two
13758 constant operands OP0 and OP1, return the result of the
13759 relational operation. If the result is not a compile time
13760 constant, then return NULL_TREE. */
13762 static tree
13764 {
13767 /* From here on, the only cases we handle are when the result is
13768 known to be a constant. */
13771 {
13775 /* Handle the cases where either operand is a NaN. */
13777 {
13779 {
13807 }
13810 }
13813 }
13815 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13817 To compute GT, swap the arguments and do LT.
13818 To compute GE, do LT and invert the result.
13819 To compute LE, swap the arguments, do LT and invert the result.
13820 To compute NE, do EQ and invert the result.
13822 Therefore, the code below must handle only EQ and LT. */
13825 {
13830 }
13832 /* Note that it is safe to invert for real values here because we
13833 have already handled the one case that it matters. */
13837 {
13840 }
13842 /* Compute a result for LT or EQ if args permit;
13843 Otherwise return T. */
13845 {
13850 else
13852 }
13853 else
13859 }
13861 /* Build an expression for the a clean point containing EXPR with type TYPE.
13862 Don't build a cleanup point expression for EXPR which don't have side
13863 effects. */
13865 tree
13867 {
13868 /* If the expression does not have side effects then we don't have to wrap
13869 it with a cleanup point expression. */
13873 /* If the expression is a return, check to see if the expression inside the
13874 return has no side effects or the right hand side of the modify expression
13875 inside the return. If either don't have side effects set we don't need to
13876 wrap the expression in a cleanup point expression. Note we don't check the
13877 left hand side of the modify because it should always be a return decl. */
13879 {
13886 }
13889 }
13891 /* Build an expression for the address of T. Folds away INDIRECT_REF to
13892 avoid confusing the gimplify process. */
13894 tree
13896 {
13897 /* The size of the object is not relevant when talking about its address. */
13901 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
13904 {
13908 }
13909 else
13910 {
13919 }
13922 }
13924 tree
13926 {
13928 }
13930 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13931 of an indirection through OP0, or NULL_TREE if no simplification is
13932 possible. */
13934 tree
13936 {
13938 tree subtype;
13946 {
13949 /* *&CONST_DECL -> to the value of the const decl. */
13952 /* *&p => p; make sure to handle *&"str"[cst] here. */
13954 {
13958 else
13960 }
13961 /* *(foo *)&fooarray => fooarray[0] */
13964 {
13970 }
13971 /* *(foo *)&complexfoo => __real__ complexfoo */
13975 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
13978 {
13982 }
13983 }
13985 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13988 {
13991 tree op00type;
13998 {
14002 }
14003 }
14005 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14008 {
14009 tree type_domain;
14016 }
14019 }
14021 /* Builds an expression for an indirection through T, simplifying some
14022 cases. */
14024 tree
14026 {
14032 else
14034 }
14036 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14038 tree
14040 {
14045 else
14047 }
14049 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14050 whose result is ignored. The type of the returned tree need not be
14051 the same as the original expression. */
14053 tree
14055 {
14061 {
14072 else
14078 {
14094 }
14099 }
14100 }
14102 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
14103 This can only be applied to objects of a sizetype. */
14105 tree
14107 {
14114 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14115 have to do anything. Only do this when we are not given a const,
14116 because in that case, this check is more expensive than just
14117 doing it. */
14119 {
14124 }
14126 /* If divisor is a power of two, simplify this to bit manipulation. */
14128 {
14130 {
14143 {
14144 high++;
14147 }
14151 }
14152 else
14153 {
14154 tree t;
14160 }
14161 }
14162 else
14163 {
14168 }
14171 }
14173 /* Likewise, but round down. */
14175 tree
14177 {
14184 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14185 have to do anything. Only do this when we are not given a const,
14186 because in that case, this check is more expensive than just
14187 doing it. */
14189 {
14194 }
14196 /* If divisor is a power of two, simplify this to bit manipulation. */
14198 {
14199 tree t;
14203 }
14204 else
14205 {
14210 }
14213 }
14215 /* Returns the pointer to the base of the object addressed by EXP and
14216 extracts the information about the offset of the access, storing it
14217 to PBITPOS and POFFSET. */
14219 static tree
14222 {
14223 tree core;
14226 HOST_WIDE_INT bitsize;
14229 {
14234 }
14235 else
14236 {
14240 }
14243 }
14245 /* Returns true if addresses of E1 and E2 differ by a constant, false
14246 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14248 bool
14250 {
14264 {
14274 }
14276 {
14277 /* If only one of the offsets is non-constant, the difference cannot
14278 be a constant. */
14280 }
14281 else
14286 }
14288 /* Simplify the floating point expression EXP when the sign of the
14289 result is not significant. Return NULL_TREE if no simplification
14290 is possible. */
14292 tree
14294 {
14298 {
14333 {
14336 {
14338 /* Strip copysign function call, return the 1st argument. */
14344 /* Strip sign ops from the argument of "odd" math functions. */
14346 {
14351 arg0));
14352 }
14354 }
14355 }
14360 }
14362 }