| blob | ca07cf16720427edfad48c1e39044ede0fccbdc9 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide, size_binop
31 and force_fit_type_double.
33 fold takes a tree as argument and returns a simplified tree.
35 size_binop takes a tree code for an arithmetic operation
36 and two operands that are trees, and produces a tree for the
37 result, assuming the type comes from `sizetype'.
39 size_int takes an integer value, and creates a tree constant
40 with type from `sizetype'.
42 force_fit_type_double takes a constant, an overflowable flag and a
43 prior overflow indicator. It forces the value to fit the type and
44 sets TREE_OVERFLOW.
46 Note: Since the folders get called on non-gimple code as well as
47 gimple code, we need to handle GIMPLE tuples as well as their
48 corresponding tree equivalents. */
70 /* Nonzero if we are folding constants inside an initializer; zero
71 otherwise. */
74 /* The following constants represent a bit based encoding of GCC's
75 comparison operators. This encoding simplifies transformations
76 on relational comparison operators, such as AND and OR. */
94 };
125 tree);
147 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
148 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
149 and SUM1. Then this yields nonzero if overflow occurred during the
150 addition.
152 Overflow occurs if A and B have the same sign, but A and SUM differ in
153 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
154 sign. */
155 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
156 \f
157 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
158 We do that by representing the two-word integer in 4 words, with only
159 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
160 number. The value of the word is LOWPART + HIGHPART * BASE. */
162 #define LOWPART(x) \
163 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
164 #define HIGHPART(x) \
165 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
166 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
168 /* Unpack a two-word integer into 4 words.
169 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
170 WORDS points to the array of HOST_WIDE_INTs. */
172 static void
174 {
179 }
181 /* Pack an array of 4 words into a two-word integer.
182 WORDS points to the array of words.
183 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
185 static void
188 {
191 }
192 \f
193 /* Force the double-word integer L1, H1 to be within the range of the
194 integer type TYPE. Stores the properly truncated and sign-extended
195 double-word integer in *LV, *HV. Returns true if the operation
196 overflows, that is, argument and result are different. */
198 int
201 {
210 else
213 /* Size types *are* sign extended. */
218 /* First clear all bits that are beyond the type's precision. */
220 ;
223 else
224 {
228 }
230 /* Then do sign extension if necessary. */
236 {
237 /* Sign extend top half? */
241 }
243 {
246 }
247 else
248 {
249 /* Sign extend bottom half? */
251 {
254 }
255 }
260 /* If the value didn't fit, signal overflow. */
262 }
264 /* We force the double-int HIGH:LOW to the range of the type TYPE by
265 sign or zero extending it.
266 OVERFLOWABLE indicates if we are interested
267 in overflow of the value, when >0 we are only interested in signed
268 overflow, for <0 we are interested in any overflow. OVERFLOWED
269 indicates whether overflow has already occurred. CONST_OVERFLOWED
270 indicates whether constant overflow has already occurred. We force
271 T's value to be within range of T's type (by setting to 0 or 1 all
272 the bits outside the type's range). We set TREE_OVERFLOWED if,
273 OVERFLOWED is nonzero,
274 or OVERFLOWABLE is >0 and signed overflow occurs
275 or OVERFLOWABLE is <0 and any overflow occurs
276 We return a new tree node for the extended double-int. The node
277 is shared if no overflow flags are set. */
279 tree
283 {
287 /* Size types *are* sign extended. */
294 /* If we need to set overflow flags, return a new unshared node. */
296 {
300 {
307 }
308 }
310 /* Else build a shared node. */
312 }
313 \f
314 /* Add two doubleword integers with doubleword result.
315 Return nonzero if the operation overflows according to UNSIGNED_P.
316 Each argument is given as two `HOST_WIDE_INT' pieces.
317 One argument is L1 and H1; the other, L2 and H2.
318 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
320 int
325 {
327 HOST_WIDE_INT h;
337 else
339 }
341 /* Negate a doubleword integer with doubleword result.
342 Return nonzero if the operation overflows, assuming it's signed.
343 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
344 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
346 int
349 {
351 {
355 }
356 else
357 {
361 }
362 }
363 \f
364 /* Multiply two doubleword integers with doubleword result.
365 Return nonzero if the operation overflows according to UNSIGNED_P.
366 Each argument is given as two `HOST_WIDE_INT' pieces.
367 One argument is L1 and H1; the other, L2 and H2.
368 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
370 int
375 {
390 {
393 {
395 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
397 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
401 }
403 }
408 /* Unsigned overflow is immediate. */
412 /* Check for signed overflow by calculating the signed representation of the
413 top half of the result; it should agree with the low half's sign bit. */
415 {
418 }
420 {
423 }
425 }
426 \f
427 /* Shift the doubleword integer in L1, H1 left by COUNT places
428 keeping only PREC bits of result.
429 Shift right if COUNT is negative.
430 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
431 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
433 void
437 {
441 {
444 }
450 {
451 /* Shifting by the host word size is undefined according to the
452 ANSI standard, so we must handle this as a special case. */
455 }
457 {
460 }
461 else
462 {
466 }
468 /* Sign extend all bits that are beyond the precision. */
476 ;
478 {
481 }
482 else
483 {
487 }
488 }
490 /* Shift the doubleword integer in L1, H1 right by COUNT places
491 keeping only PREC bits of result. COUNT must be positive.
492 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
493 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
495 void
500 {
503 signmask = (arith
511 {
512 /* Shifting by the host word size is undefined according to the
513 ANSI standard, so we must handle this as a special case. */
516 }
518 {
521 }
522 else
523 {
527 }
529 /* Zero / sign extend all bits that are beyond the precision. */
532 {
535 }
537 ;
539 {
542 }
543 else
544 {
548 }
549 }
550 \f
551 /* Rotate the doubleword integer in L1, H1 left by COUNT places
552 keeping only PREC bits of result.
553 Rotate right if COUNT is negative.
554 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
556 void
560 {
572 }
574 /* Rotate the doubleword integer in L1, H1 left by COUNT places
575 keeping only PREC bits of result. COUNT must be positive.
576 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
578 void
582 {
594 }
595 \f
596 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
597 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
598 CODE is a tree code for a kind of division, one of
599 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
600 or EXACT_DIV_EXPR
601 It controls how the quotient is rounded to an integer.
602 Return nonzero if the operation overflows.
603 UNS nonzero says do unsigned division. */
605 int
608 HOST_WIDE_INT hnum_orig,
610 HOST_WIDE_INT hden_orig,
614 {
630 /* Calculate quotient sign and convert operands to unsigned. */
632 {
634 {
636 /* (minimum integer) / (-1) is the only overflow case. */
640 }
642 {
645 }
646 }
651 /* This unsigned division rounds toward zero. */
654 }
658 /* hden != 0 already checked. */
663 }
673 /* Special code for when the divisor < BASE. */
675 {
676 /* hnum != 0 already checked. */
678 {
682 }
683 }
684 else
685 {
686 /* Full double precision division,
687 with thanks to Don Knuth's "Seminumerical Algorithms". */
691 /* Find the highest nonzero divisor digit. */
694 {
697 }
699 /* Insure that the first digit of the divisor is at least BASE/2.
700 This is required by the quotient digit estimation algorithm. */
707 {
711 }
716 {
721 }
722 }
726 /* Main loop */
728 {
729 /* Guess the next quotient digit, quo_est, by dividing the first
730 two remaining dividend digits by the high order quotient digit.
731 quo_est is never low and is at most 2 high. */
738 else
741 /* Refine quo_est so it's usually correct, and at most one high. */
746 quo_est--;
748 /* Try QUO_EST as the quotient digit, by multiplying the
749 divisor by QUO_EST and subtracting from the remaining dividend.
750 Keep in mind that QUO_EST is the I - 1st digit. */
754 {
760 }
762 /* If quo_est was high by one, then num[i] went negative and
763 we need to correct things. */
765 {
766 quo_est--;
769 {
773 }
776 }
778 /* Store the quotient digit. */
780 }
781 }
785 finish_up:
786 /* If result is negative, make it so. */
790 /* Compute trial remainder: rem = num - (quo * den) */
796 {
805 {
806 /* quo = quo - 1; */
809 }
810 else
817 {
820 }
821 else
827 {
833 /* Get absolute values. */
839 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
848 {
850 /* quo = quo - 1; */
853 else
854 /* quo = quo + 1; */
857 }
858 else
860 }
865 }
867 /* Compute true remainder: rem = num - (quo * den) */
872 }
874 /* If ARG2 divides ARG1 with zero remainder, carries out the division
875 of type CODE and returns the quotient.
876 Otherwise returns NULL_TREE. */
878 tree
880 {
890 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
891 &obj[some_exotic_number]. */
893 {
897 type);
898 }
899 else
910 }
911 \f
912 /* This is nonzero if we should defer warnings about undefined
913 overflow. This facility exists because these warnings are a
914 special case. The code to estimate loop iterations does not want
915 to issue any warnings, since it works with expressions which do not
916 occur in user code. Various bits of cleanup code call fold(), but
917 only use the result if it has certain characteristics (e.g., is a
918 constant); that code only wants to issue a warning if the result is
919 used. */
923 /* If a warning about undefined overflow is deferred, this is the
924 warning. Note that this may cause us to turn two warnings into
925 one, but that is fine since it is sufficient to only give one
926 warning per expression. */
930 /* If a warning about undefined overflow is deferred, this is the
931 level at which the warning should be emitted. */
935 /* Start deferring overflow warnings. We could use a stack here to
936 permit nested calls, but at present it is not necessary. */
938 void
940 {
942 }
944 /* Stop deferring overflow warnings. If there is a pending warning,
945 and ISSUE is true, then issue the warning if appropriate. STMT is
946 the statement with which the warning should be associated (used for
947 location information); STMT may be NULL. CODE is the level of the
948 warning--a warn_strict_overflow_code value. This function will use
949 the smaller of CODE and the deferred code when deciding whether to
950 issue the warning. CODE may be zero to mean to always use the
951 deferred code. */
953 void
955 {
957 location_t locus;
962 {
968 }
979 /* Use the smallest code level when deciding to issue the
980 warning. */
989 else
992 }
994 /* Stop deferring overflow warnings, ignoring any deferred
995 warnings. */
997 void
999 {
1001 }
1003 /* Whether we are deferring overflow warnings. */
1005 bool
1007 {
1009 }
1011 /* This is called when we fold something based on the fact that signed
1012 overflow is undefined. */
1014 static void
1016 {
1018 {
1021 {
1024 }
1025 }
1028 }
1029 \f
1030 /* Return true if the built-in mathematical function specified by CODE
1031 is odd, i.e. -f(x) == f(-x). */
1033 static bool
1035 {
1037 {
1071 }
1073 }
1075 /* Check whether we may negate an integer constant T without causing
1076 overflow. */
1078 bool
1080 {
1083 tree type;
1093 {
1098 }
1099 else
1104 }
1106 /* Determine whether an expression T can be cheaply negated using
1107 the function negate_expr without introducing undefined overflow. */
1109 static bool
1111 {
1112 tree type;
1121 {
1126 /* Check that -CST will not overflow type. */
1152 /* -(A + B) -> (-B) - A. */
1157 /* -(A + B) -> (-A) - B. */
1161 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1171 /* Fall through. */
1184 /* In general we can't negate A / B, because if A is INT_MIN and
1185 B is 1, we may turn this into INT_MIN / -1 which is undefined
1186 and actually traps on some architectures. But if overflow is
1187 undefined, we can negate, because - (INT_MIN / 1) is an
1188 overflow. */
1196 /* Negate -((double)float) as (double)(-float). */
1198 {
1202 }
1206 /* Negate -f(x) as f(-x). */
1212 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1214 {
1220 }
1225 }
1227 }
1229 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1230 simplification is possible.
1231 If negate_expr_p would return true for T, NULL_TREE will never be
1232 returned. */
1234 static tree
1236 {
1238 tree tem;
1241 {
1242 /* Convert - (~A) to A + 1. */
1258 /* Two's complement FP formats, such as c4x, may overflow. */
1268 {
1277 }
1299 {
1300 /* -(A + B) -> (-B) - A. */
1304 {
1308 }
1310 /* -(A + B) -> (-A) - B. */
1312 {
1316 }
1317 }
1321 /* - (A - B) -> B - A */
1333 /* Fall through. */
1337 {
1346 }
1354 /* In general we can't negate A / B, because if A is INT_MIN and
1355 B is 1, we may turn this into INT_MIN / -1 which is undefined
1356 and actually traps on some architectures. But if overflow is
1357 undefined, we can negate, because - (INT_MIN / 1) is an
1358 overflow. */
1360 {
1365 {
1372 }
1375 {
1382 }
1383 }
1387 /* Convert -((double)float) into (double)(-float). */
1389 {
1393 }
1397 /* Negate -f(x) as f(-x). */
1400 {
1406 }
1410 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1412 {
1417 {
1424 }
1425 }
1430 }
1433 }
1435 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1436 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1437 return NULL_TREE. */
1439 static tree
1441 {
1454 }
1455 \f
1456 /* Split a tree IN into a constant, literal and variable parts that could be
1457 combined with CODE to make IN. "constant" means an expression with
1458 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1459 commutative arithmetic operation. Store the constant part into *CONP,
1460 the literal in *LITP and return the variable part. If a part isn't
1461 present, set it to null. If the tree does not decompose in this way,
1462 return the entire tree as the variable part and the other parts as null.
1464 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1465 case, we negate an operand that was subtracted. Except if it is a
1466 literal for which we use *MINUS_LITP instead.
1468 If NEGATE_P is true, we are negating all of IN, again except a literal
1469 for which we use *MINUS_LITP instead.
1471 If IN is itself a literal or constant, return it as appropriate.
1473 Note that we do not guarantee that any of the three values will be the
1474 same type as IN, but they will have the same signedness and mode. */
1476 static tree
1479 {
1486 /* Strip any conversions that don't change the machine mode or signedness. */
1495 /* We can associate addition and subtraction together (even
1496 though the C standard doesn't say so) for integers because
1497 the value is not affected. For reals, the value might be
1498 affected, so we can't. */
1501 {
1507 /* First see if either of the operands is a literal, then a constant. */
1520 /* If we haven't dealt with either operand, this is not a case we can
1521 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1526 else
1529 /* Now do any needed negations. */
1536 }
1539 else
1543 {
1550 }
1553 }
1555 /* Re-associate trees split by the above function. T1 and T2 are either
1556 expressions to associate or null. Return the new expression, if any. If
1557 we build an operation, do it in TYPE and with CODE. */
1559 static tree
1561 {
1567 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1568 try to fold this since we will have infinite recursion. But do
1569 deal with any NEGATE_EXPRs. */
1572 {
1574 {
1583 }
1585 {
1588 }
1592 }
1596 }
1597 \f
1598 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1599 for use in int_const_binop, size_binop and size_diffop. */
1601 static bool
1603 {
1610 {
1619 }
1624 }
1627 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1628 to produce a new constant. Return NULL_TREE if we don't know how
1629 to evaluate CODE at compile-time.
1631 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1633 tree
1635 {
1639 HOST_WIDE_INT hi;
1641 HOST_WIDE_INT garbageh;
1642 tree t;
1645 int is_sizetype
1655 {
1671 /* It's unclear from the C standard whether shifts can overflow.
1672 The following code ignores overflow; perhaps a C standard
1673 interpretation ruling is needed. */
1702 /* This is a shortcut for a common special case. */
1707 {
1713 }
1715 /* ... fall through ... */
1721 {
1724 }
1727 {
1730 }
1737 /* This is a shortcut for a common special case. */
1742 {
1747 }
1749 /* ... fall through ... */
1767 else
1773 else
1779 }
1782 {
1785 /* Propagate overflow flags ourselves. */
1788 {
1791 }
1792 }
1793 else
1799 }
1801 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1802 constant. We assume ARG1 and ARG2 have the same data type, or at least
1803 are the same kind of constant and the same machine mode. Return zero if
1804 combining the constants is not allowed in the current operating mode.
1806 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1808 static tree
1810 {
1811 /* Sanity check for the recursive cases. */
1822 {
1824 REAL_VALUE_TYPE d1;
1825 REAL_VALUE_TYPE d2;
1826 REAL_VALUE_TYPE value;
1827 REAL_VALUE_TYPE result;
1831 /* The following codes are handled by real_arithmetic. */
1833 {
1844 }
1852 /* Don't perform operation if we honor signaling NaNs and
1853 either operand is a NaN. */
1858 /* Don't perform operation if it would raise a division
1859 by zero exception. */
1865 /* If either operand is a NaN, just return it. Otherwise, set up
1866 for floating-point trap; we return an overflow. */
1875 /* Don't constant fold this floating point operation if
1876 the result has overflowed and flag_trapping_math. */
1884 /* Don't constant fold this floating point operation if the
1885 result may dependent upon the run-time rounding mode and
1886 flag_rounding_math is set, or if GCC's software emulation
1887 is unable to accurately represent the result. */
1897 }
1900 {
1901 FIXED_VALUE_TYPE f1;
1902 FIXED_VALUE_TYPE f2;
1903 FIXED_VALUE_TYPE result;
1908 /* The following codes are handled by fixed_arithmetic. */
1910 {
1927 }
1934 /* Propagate overflow flags. */
1938 }
1941 {
1950 {
1961 notrunc);
1965 notrunc);
1969 {
1970 tree magsquared
1974 notrunc);
1975 tree t1
1979 notrunc);
1980 tree t2
1984 notrunc);
1991 }
1996 }
2000 }
2003 {
2015 {
2018 /* The trailing elements can be empty and should be treated as 0 */
2021 else
2022 {
2025 }
2029 else
2030 {
2033 }
2037 /* It is possible that const_binop cannot handle the given
2038 code and return NULL_TREE */
2043 }
2045 }
2047 }
2049 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2050 indicates which particular sizetype to create. */
2052 tree
2054 {
2056 }
2057 \f
2058 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2059 is a tree code. The type of the result is taken from the operands.
2060 Both must be equivalent integer types, ala int_binop_types_match_p.
2061 If the operands are constant, so is the result. */
2063 tree
2065 {
2074 /* Handle the special case of two integer constants faster. */
2076 {
2077 /* And some specific cases even faster than that. */
2079 {
2084 }
2086 {
2089 }
2091 {
2094 }
2096 /* Handle general case of two integer constants. */
2098 }
2101 }
2103 /* Given two values, either both of sizetype or both of bitsizetype,
2104 compute the difference between the two values. Return the value
2105 in signed type corresponding to the type of the operands. */
2107 tree
2109 {
2111 tree ctype;
2116 /* If the type is already signed, just do the simple thing. */
2124 else
2127 /* If either operand is not a constant, do the conversions to the signed
2128 type and subtract. The hardware will do the right thing with any
2129 overflow in the subtraction. */
2134 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2135 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2136 overflow) and negate (which can't either). Special-case a result
2137 of zero while we're here. */
2142 else
2146 }
2147 \f
2148 /* A subroutine of fold_convert_const handling conversions of an
2149 INTEGER_CST to another integer type. */
2151 static tree
2153 {
2154 tree t;
2156 /* Given an integer constant, make new constant with new type,
2157 appropriately sign-extended or truncated. */
2160 /* Don't set the overflow when
2161 converting from a pointer, */
2163 /* or to a sizetype with same signedness
2164 and the precision is unchanged.
2165 ??? sizetype is always sign-extended,
2166 but its signedness depends on the
2167 frontend. Thus we see spurious overflows
2168 here if we do not check this. */
2183 }
2185 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2186 to an integer type. */
2188 static tree
2190 {
2192 tree t;
2194 /* The following code implements the floating point to integer
2195 conversion rules required by the Java Language Specification,
2196 that IEEE NaNs are mapped to zero and values that overflow
2197 the target precision saturate, i.e. values greater than
2198 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2199 are mapped to INT_MIN. These semantics are allowed by the
2200 C and C++ standards that simply state that the behavior of
2201 FP-to-integer conversion is unspecified upon overflow. */
2204 REAL_VALUE_TYPE r;
2208 {
2215 }
2217 /* If R is NaN, return zero and show we have an overflow. */
2219 {
2223 }
2225 /* See if R is less than the lower bound or greater than the
2226 upper bound. */
2229 {
2233 {
2237 }
2238 }
2241 {
2244 {
2247 {
2251 }
2252 }
2253 }
2261 }
2263 /* A subroutine of fold_convert_const handling conversions of a
2264 FIXED_CST to an integer type. */
2266 static tree
2268 {
2269 tree t;
2273 /* Right shift FIXED_CST to temp by fbit. */
2277 {
2282 /* Left shift temp to temp_trunc by fbit. */
2287 }
2288 else
2289 {
2294 }
2296 /* If FIXED_CST is negative, we need to round the value toward 0.
2297 By checking if the fractional bits are not zero to add 1 to temp. */
2300 {
2301 double_int one;
2305 }
2307 /* Given a fixed-point constant, make new constant with new type,
2308 appropriately sign-extended or truncated. */
2316 }
2318 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2319 to another floating point type. */
2321 static tree
2323 {
2324 REAL_VALUE_TYPE value;
2325 tree t;
2332 }
2334 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2335 to a floating point type. */
2337 static tree
2339 {
2340 REAL_VALUE_TYPE value;
2341 tree t;
2348 }
2350 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2351 to another fixed-point type. */
2353 static tree
2355 {
2356 FIXED_VALUE_TYPE value;
2357 tree t;
2364 /* Propagate overflow flags. */
2368 }
2370 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2371 to a fixed-point type. */
2373 static tree
2375 {
2376 FIXED_VALUE_TYPE value;
2377 tree t;
2386 /* Propagate overflow flags. */
2390 }
2392 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2393 to a fixed-point type. */
2395 static tree
2397 {
2398 FIXED_VALUE_TYPE value;
2399 tree t;
2407 /* Propagate overflow flags. */
2411 }
2413 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2414 type TYPE. If no simplification can be done return NULL_TREE. */
2416 static tree
2418 {
2424 {
2431 }
2433 {
2440 }
2442 {
2449 }
2451 }
2453 /* Construct a vector of zero elements of vector type TYPE. */
2455 static tree
2457 {
2468 }
2470 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2472 bool
2474 {
2489 {
2508 }
2509 }
2511 /* Convert expression ARG to type TYPE. Used by the middle-end for
2512 simple conversions in preference to calling the front-end's convert. */
2514 tree
2516 {
2518 tree tem;
2532 {
2537 {
2541 }
2546 {
2549 }
2556 {
2560 }
2562 {
2566 }
2568 {
2572 }
2575 {
2593 }
2598 {
2602 }
2605 {
2619 }
2623 {
2633 {
2637 {
2641 }
2649 }
2653 }
2671 }
2672 }
2673 \f
2674 /* Return false if expr can be assumed not to be an lvalue, true
2675 otherwise. */
2677 static bool
2679 {
2680 /* We only need to wrap lvalue tree codes. */
2682 {
2716 /* Assume the worst for front-end tree codes. */
2720 }
2723 }
2725 /* Return an expr equal to X but certainly not valid as an lvalue. */
2727 tree
2729 {
2730 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2731 us. */
2738 }
2740 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2741 Zero means allow extended lvalues. */
2745 /* When pedantic, return an expr equal to X but certainly not valid as a
2746 pedantic lvalue. Otherwise, return X. */
2748 static tree
2750 {
2753 else
2755 }
2756 \f
2757 /* Given a tree comparison code, return the code that is the logical inverse
2758 of the given code. It is not safe to do this for floating-point
2759 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2760 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2762 enum tree_code
2764 {
2769 {
2800 }
2801 }
2803 /* Similar, but return the comparison that results if the operands are
2804 swapped. This is safe for floating-point. */
2806 enum tree_code
2808 {
2810 {
2836 }
2837 }
2840 /* Convert a comparison tree code from an enum tree_code representation
2841 into a compcode bit-based encoding. This function is the inverse of
2842 compcode_to_comparison. */
2844 static enum comparison_code
2846 {
2848 {
2879 }
2880 }
2882 /* Convert a compcode bit-based encoding of a comparison operator back
2883 to GCC's enum tree_code representation. This function is the
2884 inverse of comparison_to_compcode. */
2886 static enum tree_code
2888 {
2890 {
2921 }
2922 }
2924 /* Return a tree for the comparison which is the combination of
2925 doing the AND or OR (depending on CODE) of the two operations LCODE
2926 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2927 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2928 if this makes the transformation invalid. */
2930 tree
2934 {
2941 {
2952 }
2955 {
2956 /* Eliminate unordered comparisons, as well as LTGT and ORD
2957 which are not used unless the mode has NaNs. */
2963 }
2965 {
2966 /* Check that the original operation and the optimized ones will trap
2967 under the same condition. */
2978 /* In a short-circuited boolean expression the LHS might be
2979 such that the RHS, if evaluated, will never trap. For
2980 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2981 if neither x nor y is NaN. (This is a mixed blessing: for
2982 example, the expression above will never trap, hence
2983 optimizing it to x < y would be invalid). */
2988 /* If the comparison was short-circuited, and only the RHS
2989 trapped, we may now generate a spurious trap. */
2994 /* If we changed the conditions that cause a trap, we lose. */
2997 }
3003 else
3006 }
3007 \f
3008 /* Return nonzero if two operands (typically of the same tree node)
3009 are necessarily equal. If either argument has side-effects this
3010 function returns zero. FLAGS modifies behavior as follows:
3012 If OEP_ONLY_CONST is set, only return nonzero for constants.
3013 This function tests whether the operands are indistinguishable;
3014 it does not test whether they are equal using C's == operation.
3015 The distinction is important for IEEE floating point, because
3016 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3017 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3019 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3020 even though it may hold multiple values during a function.
3021 This is because a GCC tree node guarantees that nothing else is
3022 executed between the evaluation of its "operands" (which may often
3023 be evaluated in arbitrary order). Hence if the operands themselves
3024 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3025 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3026 unset means assuming isochronic (or instantaneous) tree equivalence.
3027 Unless comparing arbitrary expression trees, such as from different
3028 statements, this flag can usually be left unset.
3030 If OEP_PURE_SAME is set, then pure functions with identical arguments
3031 are considered the same. It is used when the caller has other ways
3032 to ensure that global memory is unchanged in between. */
3034 int
3036 {
3037 /* If either is ERROR_MARK, they aren't equal. */
3041 /* Check equality of integer constants before bailing out due to
3042 precision differences. */
3046 /* If both types don't have the same signedness, then we can't consider
3047 them equal. We must check this before the STRIP_NOPS calls
3048 because they may change the signedness of the arguments. As pointers
3049 strictly don't have a signedness, require either two pointers or
3050 two non-pointers as well. */
3055 /* If both types don't have the same precision, then it is not safe
3056 to strip NOPs. */
3063 /* In case both args are comparisons but with different comparison
3064 code, try to swap the comparison operands of one arg to produce
3065 a match and compare that variant. */
3069 {
3077 }
3080 /* This is needed for conversions and for COMPONENT_REF.
3081 Might as well play it safe and always test this. */
3087 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3088 We don't care about side effects in that case because the SAVE_EXPR
3089 takes care of that for us. In all other cases, two expressions are
3090 equal if they have no side effects. If we have two identical
3091 expressions with side effects that should be treated the same due
3092 to the only side effects being identical SAVE_EXPR's, that will
3093 be detected in the recursive calls below. */
3099 /* Next handle constant cases, those for which we can return 1 even
3100 if ONLY_CONST is set. */
3103 {
3118 {
3119 /* If we do not distinguish between signed and unsigned zero,
3120 consider them equal. */
3123 }
3127 {
3133 {
3135 flags))
3139 }
3142 }
3146 flags)
3148 flags));
3161 }
3166 /* Define macros to test an operand from arg0 and arg1 for equality and a
3167 variant that allows null and views null as being different from any
3168 non-null value. In the latter case, if either is null, the both
3169 must be; otherwise, do the normal comparison. */
3170 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3171 TREE_OPERAND (arg1, N), flags)
3173 #define OP_SAME_WITH_NULL(N) \
3174 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3175 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3178 {
3180 /* Two conversions are equal only if signedness and modes match. */
3182 {
3183 CASE_CONVERT:
3191 }
3201 /* For commutative ops, allow the other order. */
3209 /* If either of the pointer (or reference) expressions we are
3210 dereferencing contain a side effect, these cannot be equal. */
3216 {
3226 /* Operands 2 and 3 may be null.
3227 Compare the array index by value if it is constant first as we
3228 may have different types but same value here. */
3237 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3238 may be NULL when we're called to compare MEM_EXPRs. */
3248 }
3252 {
3267 /* Otherwise take into account this is a commutative operation. */
3278 }
3282 {
3284 /* If the CALL_EXPRs call different functions, then they
3285 clearly can not be equal. */
3287 flags))
3290 {
3294 else
3298 }
3300 /* Now see if all the arguments are the same. */
3301 {
3312 /* If we get here and both argument lists are exhausted
3313 then the CALL_EXPRs are equal. */
3315 }
3318 }
3321 /* Consider __builtin_sqrt equal to sqrt. */
3329 }
3331 #undef OP_SAME
3332 #undef OP_SAME_WITH_NULL
3333 }
3334 \f
3335 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3336 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3338 When in doubt, return 0. */
3340 static int
3342 {
3354 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3355 and see if the inner values are the same. This removes any
3356 signedness comparison, which doesn't matter here. */
3363 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3364 actual comparison operand, ARG0.
3366 First throw away any conversions to wider types
3367 already present in the operands. */
3376 {
3379 /* Make sure shorter operand is extended the right way
3380 to match the longer operand. */
3386 }
3389 }
3390 \f
3391 /* See if ARG is an expression that is either a comparison or is performing
3392 arithmetic on comparisons. The comparisons must only be comparing
3393 two different values, which will be stored in *CVAL1 and *CVAL2; if
3394 they are nonzero it means that some operands have already been found.
3395 No variables may be used anywhere else in the expression except in the
3396 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3397 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3399 If this is true, return 1. Otherwise, return zero. */
3401 static int
3403 {
3407 /* We can handle some of the tcc_expression cases here. */
3417 {
3418 /* If we've already found a CVAL1 or CVAL2, this expression is
3419 two complex to handle. */
3425 }
3428 {
3451 /* First see if we can handle the first operand, then the second. For
3452 the second operand, we know *CVAL1 can't be zero. It must be that
3453 one side of the comparison is each of the values; test for the
3454 case where this isn't true by failing if the two operands
3455 are the same. */
3464 ;
3468 ;
3469 else
3473 ;
3477 ;
3478 else
3485 }
3486 }
3487 \f
3488 /* ARG is a tree that is known to contain just arithmetic operations and
3489 comparisons. Evaluate the operations in the tree substituting NEW0 for
3490 any occurrence of OLD0 as an operand of a comparison and likewise for
3491 NEW1 and OLD1. */
3493 static tree
3495 {
3500 /* We can handle some of the tcc_expression cases here. */
3508 {
3523 {
3540 }
3541 /* Fall through - ??? */
3544 {
3548 /* We need to check both for exact equality and tree equality. The
3549 former will be true if the operand has a side-effect. In that
3550 case, we know the operand occurred exactly once. */
3563 }
3567 }
3568 }
3569 \f
3570 /* Return a tree for the case when the result of an expression is RESULT
3571 converted to TYPE and OMITTED was previously an operand of the expression
3572 but is now not needed (e.g., we folded OMITTED * 0).
3574 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3575 the conversion of RESULT to TYPE. */
3577 tree
3579 {
3582 /* If the resulting operand is an empty statement, just return the omitted
3583 statement casted to void. */
3591 }
3593 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3595 static tree
3597 {
3600 /* If the resulting operand is an empty statement, just return the omitted
3601 statement casted to void. */
3609 }
3611 /* Return a tree for the case when the result of an expression is RESULT
3612 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3613 of the expression but are now not needed.
3615 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3616 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3617 evaluated before OMITTED2. Otherwise, if neither has side effects,
3618 just do the conversion of RESULT to TYPE. */
3620 tree
3622 {
3631 }
3633 \f
3634 /* Return a simplified tree node for the truth-negation of ARG. This
3635 never alters ARG itself. We assume that ARG is an operation that
3636 returns a truth value (0 or 1).
3638 FIXME: one would think we would fold the result, but it causes
3639 problems with the dominator optimizer. */
3641 tree
3643 {
3647 /* If this is a comparison, we can simply invert it, except for
3648 floating-point non-equality comparisons, in which case we just
3649 enclose a TRUTH_NOT_EXPR around what we have. */
3652 {
3655 && flag_trapping_math
3668 }
3671 {
3688 /* Here we can invert either operand. We invert the first operand
3689 unless the second operand is a TRUTH_NOT_EXPR in which case our
3690 result is the XOR of the first operand with the inside of the
3691 negation of the second operand. */
3696 else
3718 {
3721 /* A COND_EXPR may have a throw as one operand, which
3722 then has void type. Just leave void operands
3723 as they are. */
3730 }
3742 {
3745 }
3747 /* ... fall through ... */
3773 }
3779 }
3781 /* Return a simplified tree node for the truth-negation of ARG. This
3782 never alters ARG itself. We assume that ARG is an operation that
3783 returns a truth value (0 or 1).
3785 FIXME: one would think we would fold the result, but it causes
3786 problems with the dominator optimizer. */
3788 tree
3790 {
3791 tree tem;
3801 }
3803 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3804 operands are another bit-wise operation with a common input. If so,
3805 distribute the bit operations to save an operation and possibly two if
3806 constants are involved. For example, convert
3807 (A | B) & (A | C) into A | (B & C)
3808 Further simplification will occur if B and C are constants.
3810 If this optimization cannot be done, 0 will be returned. */
3812 static tree
3814 {
3815 tree common;
3825 {
3829 }
3831 {
3835 }
3837 {
3841 }
3843 {
3847 }
3848 else
3856 }
3858 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3859 with code CODE. This optimization is unsafe. */
3860 static tree
3862 {
3866 /* (A / C) +- (B / C) -> (A +- B) / C. */
3876 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3881 {
3893 }
3896 }
3897 \f
3898 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3899 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3901 static tree
3904 {
3908 {
3915 }
3929 }
3931 /* Optimize a bit-field compare.
3933 There are two cases: First is a compare against a constant and the
3934 second is a comparison of two items where the fields are at the same
3935 bit position relative to the start of a chunk (byte, halfword, word)
3936 large enough to contain it. In these cases we can avoid the shift
3937 implicit in bitfield extractions.
3939 For constants, we emit a compare of the shifted constant with the
3940 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3941 compared. For two fields at the same position, we do the ANDs with the
3942 similar mask and compare the result of the ANDs.
3944 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3945 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3946 are the left and right operands of the comparison, respectively.
3948 If the optimization described above can be done, we return the resulting
3949 tree. Otherwise we return zero. */
3951 static tree
3954 {
3963 tree mask;
3964 tree offset;
3966 /* Get all the information about the extractions being done. If the bit size
3967 if the same as the size of the underlying object, we aren't doing an
3968 extraction at all and so can do nothing. We also don't want to
3969 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3970 then will no longer be able to replace it. */
3978 {
3979 /* If this is not a constant, we can only do something if bit positions,
3980 sizes, and signedness are the same. */
3988 }
3990 /* See if we can find a mode to refer to this field. We should be able to,
3991 but fail if we can't. */
4000 /* Set signed and unsigned types of the precision of this mode for the
4001 shifts below. */
4005 /* Compute the bit position and size for the new reference and our offset
4006 within it. If the new reference is the same size as the original, we
4007 won't optimize anything, so return zero. */
4017 /* Make the mask to be used against the extracted field. */
4024 /* If not comparing with constant, just rework the comparison
4025 and return. */
4029 unsigned_type,
4032 mask),
4035 unsigned_type,
4038 mask));
4040 /* Otherwise, we are handling the constant case. See if the constant is too
4041 big for the field. Warn and return a tree of for 0 (false) if so. We do
4042 this not only for its own sake, but to avoid having to test for this
4043 error case below. If we didn't, we might generate wrong code.
4045 For unsigned fields, the constant shifted right by the field length should
4046 be all zero. For signed fields, the high-order bits should agree with
4047 the sign bit. */
4050 {
4054 {
4058 }
4059 }
4060 else
4061 {
4065 {
4069 }
4070 }
4072 /* Single-bit compares should always be against zero. */
4074 {
4077 }
4079 /* Make a new bitfield reference, shift the constant over the
4080 appropriate number of bits and mask it with the computed mask
4081 (in case this was a signed field). If we changed it, make a new one. */
4084 {
4087 }
4097 rhs);
4098 }
4099 \f
4100 /* Subroutine for fold_truthop: decode a field reference.
4102 If EXP is a comparison reference, we return the innermost reference.
4104 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4105 set to the starting bit number.
4107 If the innermost field can be completely contained in a mode-sized
4108 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4110 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4111 otherwise it is not changed.
4113 *PUNSIGNEDP is set to the signedness of the field.
4115 *PMASK is set to the mask used. This is either contained in a
4116 BIT_AND_EXPR or derived from the width of the field.
4118 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4120 Return 0 if this is not a component reference or is one that we can't
4121 do anything with. */
4123 static tree
4128 {
4132 tree unsigned_type;
4135 /* All the optimizations using this function assume integer fields.
4136 There are problems with FP fields since the type_for_size call
4137 below can fail for, e.g., XFmode. */
4141 /* We are interested in the bare arrangement of bits, so strip everything
4142 that doesn't affect the machine mode. However, record the type of the
4143 outermost expression if it may matter below. */
4150 {
4156 }
4165 /* If the number of bits in the reference is the same as the bitsize of
4166 the outer type, then the outer type gives the signedness. Otherwise
4167 (in case of a small bitfield) the signedness is unchanged. */
4171 /* Compute the mask to access the bitfield. */
4180 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4188 }
4190 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4191 bit positions. */
4193 static int
4195 {
4198 tree tmask;
4202 return
4209 }
4211 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4212 represents the sign bit of EXP's type. If EXP represents a sign
4213 or zero extension, also test VAL against the unextended type.
4214 The return value is the (sub)expression whose sign bit is VAL,
4215 or NULL_TREE otherwise. */
4217 static tree
4219 {
4223 tree t;
4225 /* Tree EXP must have an integral type. */
4230 /* Tree VAL must be an integer constant. */
4237 {
4244 }
4245 else
4246 {
4253 }
4255 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4256 treat VAL as if it were unsigned. */
4261 /* Handle extension from a narrower type. */
4267 }
4269 /* Subroutine for fold_truthop: determine if an operand is simple enough
4270 to be evaluated unconditionally. */
4272 static int
4274 {
4275 /* Strip any conversions that don't change the machine mode. */
4284 /* Don't regard global variables as simple. They may be
4285 allocated in ways unknown to the compiler (shared memory,
4286 #pragma weak, etc). */
4289 /* Loading a static variable is unduly expensive, but global
4290 registers aren't expensive. */
4292 }
4293 \f
4294 /* The following functions are subroutines to fold_range_test and allow it to
4295 try to change a logical combination of comparisons into a range test.
4297 For example, both
4298 X == 2 || X == 3 || X == 4 || X == 5
4299 and
4300 X >= 2 && X <= 5
4301 are converted to
4302 (unsigned) (X - 2) <= 3
4304 We describe each set of comparisons as being either inside or outside
4305 a range, using a variable named like IN_P, and then describe the
4306 range with a lower and upper bound. If one of the bounds is omitted,
4307 it represents either the highest or lowest value of the type.
4309 In the comments below, we represent a range by two numbers in brackets
4310 preceded by a "+" to designate being inside that range, or a "-" to
4311 designate being outside that range, so the condition can be inverted by
4312 flipping the prefix. An omitted bound is represented by a "-". For
4313 example, "- [-, 10]" means being outside the range starting at the lowest
4314 possible value and ending at 10, in other words, being greater than 10.
4315 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4316 always false.
4318 We set up things so that the missing bounds are handled in a consistent
4319 manner so neither a missing bound nor "true" and "false" need to be
4320 handled using a special case. */
4322 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4323 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4324 and UPPER1_P are nonzero if the respective argument is an upper bound
4325 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4326 must be specified for a comparison. ARG1 will be converted to ARG0's
4327 type if both are specified. */
4329 static tree
4332 {
4333 tree tem;
4337 /* If neither arg represents infinity, do the normal operation.
4338 Else, if not a comparison, return infinity. Else handle the special
4339 comparison rules. Note that most of the cases below won't occur, but
4340 are handled for consistency. */
4343 {
4348 }
4353 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4354 for neither. In real maths, we cannot assume open ended ranges are
4355 the same. But, this is computer arithmetic, where numbers are finite.
4356 We can therefore make the transformation of any unbounded range with
4357 the value Z, Z being greater than any representable number. This permits
4358 us to treat unbounded ranges as equal. */
4362 {
4383 }
4386 }
4387 \f
4388 /* Given EXP, a logical expression, set the range it is testing into
4389 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4390 actually being tested. *PLOW and *PHIGH will be made of the same
4391 type as the returned expression. If EXP is not a comparison, we
4392 will most likely not be returning a useful value and range. Set
4393 *STRICT_OVERFLOW_P to true if the return value is only valid
4394 because signed overflow is undefined; otherwise, do not change
4395 *STRICT_OVERFLOW_P. */
4397 static tree
4400 {
4407 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4408 and see if we can refine the range. Some of the cases below may not
4409 happen, but it doesn't seem worth worrying about this. We "continue"
4410 the outer loop when we've changed something; otherwise we "break"
4411 the switch, which will "break" the while. */
4417 {
4422 {
4434 }
4437 {
4444 /* We can only do something if the range is testing for zero
4445 and if the second operand is an integer constant. Note that
4446 saying something is "in" the range we make is done by
4447 complementing IN_P since it will set in the initial case of
4448 being not equal to zero; "out" is leaving it alone. */
4455 {
4476 }
4478 /* If this is an unsigned comparison, we also know that EXP is
4479 greater than or equal to zero. We base the range tests we make
4480 on that fact, so we record it here so we can parse existing
4481 range tests. We test arg0_type since often the return type
4482 of, e.g. EQ_EXPR, is boolean. */
4484 {
4488 NULL_TREE))
4493 /* If the high bound is missing, but we have a nonzero low
4494 bound, reverse the range so it goes from zero to the low bound
4495 minus 1. */
4497 {
4502 }
4503 }
4509 /* (-x) IN [a,b] -> x in [-b, -a] */
4521 /* ~ X -> -X - 1 */
4530 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4531 move a constant to the other side. */
4536 /* If EXP is signed, any overflow in the computation is undefined,
4537 so we don't worry about it so long as our computations on
4538 the bounds don't overflow. For unsigned, overflow is defined
4539 and this is exactly the right thing. */
4551 /* Check for an unsigned range which has wrapped around the maximum
4552 value thus making n_high < n_low, and normalize it. */
4554 {
4560 /* If the range is of the form +/- [ x+1, x ], we won't
4561 be able to normalize it. But then, it represents the
4562 whole range or the empty set, so make it
4563 +/- [ -, - ]. */
4567 else
4569 }
4570 else
4594 /* If we're converting arg0 from an unsigned type, to exp,
4595 a signed type, we will be doing the comparison as unsigned.
4596 The tests above have already verified that LOW and HIGH
4597 are both positive.
4599 So we have to ensure that we will handle large unsigned
4600 values the same way that the current signed bounds treat
4601 negative values. */
4604 {
4605 tree high_positive;
4606 tree equiv_type;
4607 /* For fixed-point modes, we need to pass the saturating flag
4608 as the 2nd parameter. */
4613 else
4617 /* A range without an upper bound is, naturally, unbounded.
4618 Since convert would have cropped a very large value, use
4619 the max value for the destination type. */
4620 high_positive
4627 high_positive),
4630 /* If the low bound is specified, "and" the range with the
4631 range for which the original unsigned value will be
4632 positive. */
4634 {
4638 integer_zero_node),
4639 high_positive))
4643 }
4644 else
4645 {
4646 /* Otherwise, "or" the range with the range of the input
4647 that will be interpreted as negative. */
4651 integer_zero_node),
4652 high_positive))
4656 }
4657 }
4665 }
4668 }
4670 /* If EXP is a constant, we can evaluate whether this is true or false. */
4672 {
4679 }
4683 }
4684 \f
4685 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4686 type, TYPE, return an expression to test if EXP is in (or out of, depending
4687 on IN_P) the range. Return 0 if the test couldn't be created. */
4689 static tree
4691 {
4695 #ifdef HAVE_canonicalize_funcptr_for_compare
4696 /* Disable this optimization for function pointer expressions
4697 on targets that require function pointer canonicalization. */
4702 #endif
4705 {
4711 }
4729 {
4731 {
4735 }
4737 }
4739 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4741 {
4743 HOST_WIDE_INT hi;
4748 {
4751 }
4752 else
4753 {
4756 }
4759 {
4761 {
4764 etype
4766 else
4769 }
4772 }
4773 }
4775 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4776 This requires wrap-around arithmetics for the type of the expression. */
4779 {
4783 /* There is no requirement that LOW be within the range of ETYPE
4784 if the latter is a subtype. It must, however, be within the base
4785 type of ETYPE. So be sure we do the subtraction in that type. */
4787 {
4789 /* But not in an enumeral or boolean type though. */
4791 }
4800 }
4802 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4805 {
4808 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4809 for the type in question, as we rely on this here. */
4819 else
4821 }
4831 {
4833 {
4839 }
4841 }
4849 }
4850 \f
4851 /* Return the predecessor of VAL in its type, handling the infinite case. */
4853 static tree
4855 {
4861 else
4863 }
4865 /* Return the successor of VAL in its type, handling the infinite case. */
4867 static tree
4869 {
4875 else
4877 }
4879 /* Given two ranges, see if we can merge them into one. Return 1 if we
4880 can, 0 if we can't. Set the output range into the specified parameters. */
4882 static int
4885 {
4889 tree tem;
4899 /* Make range 0 be the range that starts first, or ends last if they
4900 start at the same value. Swap them if it isn't. */
4903 || (lowequal
4906 {
4910 }
4912 /* Now flag two cases, whether the ranges are disjoint or whether the
4913 second range is totally subsumed in the first. Note that the tests
4914 below are simplified by the ones above. */
4920 /* We now have four cases, depending on whether we are including or
4921 excluding the two ranges. */
4923 {
4924 /* If they don't overlap, the result is false. If the second range
4925 is a subset it is the result. Otherwise, the range is from the start
4926 of the second to the end of the first. */
4931 else
4933 }
4936 {
4937 /* If they don't overlap, the result is the first range. If they are
4938 equal, the result is false. If the second range is a subset of the
4939 first, and the ranges begin at the same place, we go from just after
4940 the end of the second range to the end of the first. If the second
4941 range is not a subset of the first, or if it is a subset and both
4942 ranges end at the same place, the range starts at the start of the
4943 first range and ends just before the second range.
4944 Otherwise, we can't describe this as a single range. */
4950 {
4955 {
4956 /* We are in the weird situation where high0 > high1 but
4957 high1 has no successor. Punt. */
4959 }
4960 }
4962 {
4967 {
4968 /* low0 < low1 but low1 has no predecessor. Punt. */
4970 }
4971 }
4972 else
4974 }
4977 {
4978 /* If they don't overlap, the result is the second range. If the second
4979 is a subset of the first, the result is false. Otherwise,
4980 the range starts just after the first range and ends at the
4981 end of the second. */
4986 else
4987 {
4992 {
4993 /* high1 > high0 but high0 has no successor. Punt. */
4995 }
4996 }
4997 }
4999 else
5000 {
5001 /* The case where we are excluding both ranges. Here the complex case
5002 is if they don't overlap. In that case, the only time we have a
5003 range is if they are adjacent. If the second is a subset of the
5004 first, the result is the first. Otherwise, the range to exclude
5005 starts at the beginning of the first range and ends at the end of the
5006 second. */
5008 {
5013 else
5014 {
5015 /* Canonicalize - [min, x] into - [-, x]. */
5018 {
5023 /* FALLTHROUGH */
5036 }
5038 /* Canonicalize - [x, max] into - [x, -]. */
5041 {
5046 /* FALLTHROUGH */
5061 }
5063 /* The ranges might be also adjacent between the maximum and
5064 minimum values of the given type. For
5065 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5066 return + [x + 1, y - 1]. */
5068 {
5075 }
5076 else
5078 }
5079 }
5082 else
5084 }
5088 }
5089 \f
5091 /* Subroutine of fold, looking inside expressions of the form
5092 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5093 of the COND_EXPR. This function is being used also to optimize
5094 A op B ? C : A, by reversing the comparison first.
5096 Return a folded expression whose code is not a COND_EXPR
5097 anymore, or NULL_TREE if no folding opportunity is found. */
5099 static tree
5101 {
5106 tree tem;
5111 /* If we have A op 0 ? A : -A, consider applying the following
5112 transformations:
5114 A == 0? A : -A same as -A
5115 A != 0? A : -A same as A
5116 A >= 0? A : -A same as abs (A)
5117 A > 0? A : -A same as abs (A)
5118 A <= 0? A : -A same as -abs (A)
5119 A < 0? A : -A same as -abs (A)
5121 None of these transformations work for modes with signed
5122 zeros. If A is +/-0, the first two transformations will
5123 change the sign of the result (from +0 to -0, or vice
5124 versa). The last four will fix the sign of the result,
5125 even though the original expressions could be positive or
5126 negative, depending on the sign of A.
5128 Note that all these transformations are correct if A is
5129 NaN, since the two alternatives (A and -A) are also NaNs. */
5136 /* In the case that A is of the form X-Y, '-A' (arg2) may
5137 have already been folded to Y-X, check for that. */
5145 {
5157 /* Fall through. */
5179 }
5181 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5182 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5183 both transformations are correct when A is NaN: A != 0
5184 is then true, and A == 0 is false. */
5188 {
5193 }
5195 /* Try some transformations of A op B ? A : B.
5197 A == B? A : B same as B
5198 A != B? A : B same as A
5199 A >= B? A : B same as max (A, B)
5200 A > B? A : B same as max (B, A)
5201 A <= B? A : B same as min (A, B)
5202 A < B? A : B same as min (B, A)
5204 As above, these transformations don't work in the presence
5205 of signed zeros. For example, if A and B are zeros of
5206 opposite sign, the first two transformations will change
5207 the sign of the result. In the last four, the original
5208 expressions give different results for (A=+0, B=-0) and
5209 (A=-0, B=+0), but the transformed expressions do not.
5211 The first two transformations are correct if either A or B
5212 is a NaN. In the first transformation, the condition will
5213 be false, and B will indeed be chosen. In the case of the
5214 second transformation, the condition A != B will be true,
5215 and A will be chosen.
5217 The conversions to max() and min() are not correct if B is
5218 a number and A is not. The conditions in the original
5219 expressions will be false, so all four give B. The min()
5220 and max() versions would give a NaN instead. */
5223 /* Avoid these transformations if the COND_EXPR may be used
5224 as an lvalue in the C++ front-end. PR c++/19199. */
5225 && (in_gimple_form
5230 {
5235 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5237 {
5241 }
5244 {
5253 /* In C++ a ?: expression can be an lvalue, so put the
5254 operand which will be used if they are equal first
5255 so that we can convert this back to the
5256 corresponding COND_EXPR. */
5258 {
5265 }
5272 {
5279 }
5292 }
5293 }
5295 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5296 we might still be able to simplify this. For example,
5297 if C1 is one less or one more than C2, this might have started
5298 out as a MIN or MAX and been transformed by this function.
5299 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5305 {
5307 /* We can replace A with C1 in this case. */
5312 /* If C1 is C2 + 1, this is min(A, C2). */
5314 OEP_ONLY_CONST)
5318 OEP_ONLY_CONST))
5320 type,
5322 arg2));
5326 /* If C1 is C2 - 1, this is min(A, C2). */
5328 OEP_ONLY_CONST)
5332 OEP_ONLY_CONST))
5334 type,
5336 arg2));
5340 /* If C1 is C2 - 1, this is max(A, C2). */
5342 OEP_ONLY_CONST)
5346 OEP_ONLY_CONST))
5348 type,
5350 arg2));
5354 /* If C1 is C2 + 1, this is max(A, C2). */
5356 OEP_ONLY_CONST)
5360 OEP_ONLY_CONST))
5362 type,
5364 arg2));
5370 }
5373 }
5376 \f
5377 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5378 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5379 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5380 false) >= 2)
5381 #endif
5383 /* EXP is some logical combination of boolean tests. See if we can
5384 merge it into some range test. Return the new tree if so. */
5386 static tree
5388 {
5396 tree tem;
5400 /* If this is an OR operation, invert both sides; we will invert
5401 again at the end. */
5405 /* If both expressions are the same, if we can merge the ranges, and we
5406 can build the range test, return it or it inverted. If one of the
5407 ranges is always true or always false, consider it to be the same
5408 expression as the other. */
5416 {
5420 }
5422 /* On machines where the branch cost is expensive, if this is a
5423 short-circuited branch and the underlying object on both sides
5424 is the same, make a non-short-circuit operation. */
5430 {
5431 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5432 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5433 which cases we can't do this. */
5441 {
5450 {
5453 WARN_STRICT_OVERFLOW_COMPARISON);
5457 }
5458 }
5459 }
5462 }
5463 \f
5464 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5465 bit value. Arrange things so the extra bits will be set to zero if and
5466 only if C is signed-extended to its full width. If MASK is nonzero,
5467 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5469 static tree
5471 {
5474 tree temp;
5479 /* We work by getting just the sign bit into the low-order bit, then
5480 into the high-order bit, then sign-extend. We then XOR that value
5481 with C. */
5485 /* We must use a signed type in order to get an arithmetic right shift.
5486 However, we must also avoid introducing accidental overflows, so that
5487 a subsequent call to integer_zerop will work. Hence we must
5488 do the type conversion here. At this point, the constant is either
5489 zero or one, and the conversion to a signed type can never overflow.
5490 We could get an overflow if this conversion is done anywhere else. */
5499 /* If necessary, convert the type back to match the type of C. */
5504 }
5505 \f
5506 /* Find ways of folding logical expressions of LHS and RHS:
5507 Try to merge two comparisons to the same innermost item.
5508 Look for range tests like "ch >= '0' && ch <= '9'".
5509 Look for combinations of simple terms on machines with expensive branches
5510 and evaluate the RHS unconditionally.
5512 For example, if we have p->a == 2 && p->b == 4 and we can make an
5513 object large enough to span both A and B, we can do this with a comparison
5514 against the object ANDed with the a mask.
5516 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5517 operations to do this with one comparison.
5519 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5520 function and the one above.
5522 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5523 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5525 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5526 two operands.
5528 We return the simplified tree or 0 if no optimization is possible. */
5530 static tree
5532 {
5533 /* If this is the "or" of two comparisons, we can do something if
5534 the comparisons are NE_EXPR. If this is the "and", we can do something
5535 if the comparisons are EQ_EXPR. I.e.,
5536 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5538 WANTED_CODE is this operation code. For single bit fields, we can
5539 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5540 comparison for one-bit fields. */
5562 /* Start by getting the comparison codes. Fail if anything is volatile.
5563 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5564 it were surrounded with a NE_EXPR. */
5573 {
5577 }
5580 {
5584 }
5595 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5598 {
5599 tree result;
5602 {
5607 }
5610 {
5616 }
5617 }
5622 /* If the RHS can be evaluated unconditionally and its operands are
5623 simple, it wins to evaluate the RHS unconditionally on machines
5624 with expensive branches. In this case, this isn't a comparison
5625 that can be merged. Avoid doing this if the RHS is a floating-point
5626 comparison since those can trap. */
5633 {
5634 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5645 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5657 {
5661 }
5662 }
5664 /* See if the comparisons can be merged. Then get all the parameters for
5665 each side. */
5689 /* It must be true that the inner operation on the lhs of each
5690 comparison must be the same if we are to be able to do anything.
5691 Then see if we have constants. If not, the same must be true for
5692 the rhs's. */
5703 else
5706 /* If either comparison code is not correct for our logical operation,
5707 fail. However, we can convert a one-bit comparison against zero into
5708 the opposite comparison against that bit being set in the field. */
5712 {
5714 {
5715 /* Make the left operand unsigned, since we are only interested
5716 in the value of one bit. Otherwise we are doing the wrong
5717 thing below. */
5720 }
5721 else
5723 }
5725 /* This is analogous to the code for l_const above. */
5727 {
5729 {
5732 }
5733 else
5735 }
5737 /* See if we can find a mode that contains both fields being compared on
5738 the left. If we can't, fail. Otherwise, update all constants and masks
5739 to be relative to a field of that size. */
5744 volatilep);
5754 {
5757 }
5765 {
5773 {
5777 }
5778 }
5780 {
5788 {
5792 }
5793 }
5795 /* If the right sides are not constant, do the same for it. Also,
5796 disallow this optimization if a size or signedness mismatch occurs
5797 between the left and right sides. */
5799 {
5802 /* Make sure the two fields on the right
5803 correspond to the left without being swapped. */
5811 volatilep);
5821 {
5824 }
5831 /* Make a mask that corresponds to both fields being compared.
5832 Do this for both items being compared. If the operands are the
5833 same size and the bits being compared are in the same position
5834 then we can do this by masking both and comparing the masked
5835 results. */
5839 {
5851 }
5853 /* There is still another way we can do something: If both pairs of
5854 fields being compared are adjacent, we may be able to make a wider
5855 field containing them both.
5857 Note that we still must mask the lhs/rhs expressions. Furthermore,
5858 the mask must be shifted to account for the shift done by
5859 make_bit_field_ref. */
5864 {
5865 tree type;
5877 /* Convert to the smaller type before masking out unwanted bits. */
5880 {
5882 {
5886 }
5888 {
5892 }
5893 }
5902 }
5905 }
5907 /* Handle the case of comparisons with constants. If there is something in
5908 common between the masks, those bits of the constants must be the same.
5909 If not, the condition is always false. Test for this to avoid generating
5910 incorrect code below. */
5915 {
5917 {
5920 }
5921 else
5922 {
5925 }
5926 }
5928 /* Construct the expression we will return. First get the component
5929 reference we will make. Unless the mask is all ones the width of
5930 that field, perform the mask operation. Then compare with the
5931 merged constant. */
5941 }
5942 \f
5943 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5944 constant. */
5946 static tree
5948 {
5951 tree comp_const;
5952 tree minmax_const;
5954 tree inner;
5965 /* If something does not permit us to optimize, return the original tree. */
5973 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5974 and GT_EXPR, doing the rest with recursive calls using logical
5975 simplifications. */
5977 {
5979 {
5985 }
5988 return
5990 optimize_minmax_comparison
5992 optimize_minmax_comparison
5997 /* MAX (X, 0) == 0 -> X <= 0 */
6001 /* MAX (X, 0) == 5 -> X == 5 */
6005 /* MAX (X, 0) == -1 -> false */
6009 /* MIN (X, 0) == 0 -> X >= 0 */
6013 /* MIN (X, 0) == 5 -> false */
6016 else
6017 /* MIN (X, 0) == -1 -> X == -1 */
6022 /* MAX (X, 0) > 0 -> X > 0
6023 MAX (X, 0) > 5 -> X > 5 */
6027 /* MAX (X, 0) > -1 -> true */
6031 /* MIN (X, 0) > 0 -> false
6032 MIN (X, 0) > 5 -> false */
6035 else
6036 /* MIN (X, 0) > -1 -> X > -1 */
6041 }
6042 }
6043 \f
6044 /* T is an integer expression that is being multiplied, divided, or taken a
6045 modulus (CODE says which and what kind of divide or modulus) by a
6046 constant C. See if we can eliminate that operation by folding it with
6047 other operations already in T. WIDE_TYPE, if non-null, is a type that
6048 should be used for the computation if wider than our type.
6050 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6051 (X * 2) + (Y * 4). We must, however, be assured that either the original
6052 expression would not overflow or that overflow is undefined for the type
6053 in the language in question.
6055 If we return a non-null expression, it is an equivalent form of the
6056 original computation, but need not be in the original type.
6058 We set *STRICT_OVERFLOW_P to true if the return values depends on
6059 signed overflow being undefined. Otherwise we do not change
6060 *STRICT_OVERFLOW_P. */
6062 static tree
6065 {
6066 /* To avoid exponential search depth, refuse to allow recursion past
6067 three levels. Beyond that (1) it's highly unlikely that we'll find
6068 something interesting and (2) we've probably processed it before
6069 when we built the inner expression. */
6072 tree ret;
6077 depth++;
6079 depth--;
6082 }
6084 static tree
6087 {
6098 /* Don't deal with constants of zero here; they confuse the code below. */
6108 /* Note that we need not handle conditional operations here since fold
6109 already handles those cases. So just do arithmetic here. */
6111 {
6113 /* For a constant, we can always simplify if we are a multiply
6114 or (for divide and modulus) if it is a multiple of our constant. */
6122 /* If op0 is an expression ... */
6128 /* ... and has wrapping overflow, and its type is smaller
6129 than ctype, then we cannot pass through as widening. */
6135 /* ... or this is a truncation (t is narrower than op0),
6136 then we cannot pass through this narrowing. */
6139 /* ... or signedness changes for division or modulus,
6140 then we cannot pass through this conversion. */
6144 /* ... or has undefined overflow while the converted to
6145 type has not, we cannot do the operation in the inner type
6146 as that would introduce undefined overflow. */
6151 /* Pass the constant down and see if we can make a simplification. If
6152 we can, replace this expression with the inner simplification for
6153 possible later conversion to our or some other type. */
6158 code == MULT_EXPR
6160 strict_overflow_p))))
6165 /* If widening the type changes it from signed to unsigned, then we
6166 must avoid building ABS_EXPR itself as unsigned. */
6168 {
6172 {
6175 }
6177 }
6178 /* If the constant is negative, we cannot simplify this. */
6181 /* FALLTHROUGH */
6189 /* If widening the type changes the signedness, then we can't perform
6190 this optimization as that changes the result. */
6194 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6200 {
6207 }
6211 /* If the second operand is constant, this is a multiplication
6212 or floor division, by a power of two, so we can treat it that
6213 way unless the multiplier or divisor overflows. Signed
6214 left-shift overflow is implementation-defined rather than
6215 undefined in C90, so do not convert signed left shift into
6216 multiplication. */
6219 /* const_binop may not detect overflow correctly,
6220 so check for it explicitly here. */
6225 size_one_node,
6235 /* See if we can eliminate the operation on both sides. If we can, we
6236 can return a new PLUS or MINUS. If we can't, the only remaining
6237 cases where we can do anything are if the second operand is a
6238 constant. */
6244 /* If not multiplication, we can only do this if both operands
6245 are divisible by c. */
6248 {
6253 }
6255 /* If this was a subtraction, negate OP1 and set it to be an addition.
6256 This simplifies the logic below. */
6263 /* If either OP1 or C are negative, this optimization is not safe for
6264 some of the division and remainder types while for others we need
6265 to change the code. */
6267 {
6275 }
6277 /* If it's a multiply or a division/modulus operation of a multiple
6278 of our constant, do the operation and verify it doesn't overflow. */
6281 {
6284 /* We allow the constant to overflow with wrapping semantics. */
6288 }
6289 else
6292 /* If we have an unsigned type is not a sizetype, we cannot widen
6293 the operation since it will change the result if the original
6294 computation overflowed. */
6300 /* If we were able to eliminate our operation from the first side,
6301 apply our operation to the second side and reform the PLUS. */
6305 /* The last case is if we are a multiply. In that case, we can
6306 apply the distributive law to commute the multiply and addition
6307 if the multiplication of the constants doesn't overflow. */
6313 op1);
6318 /* We have a special case here if we are doing something like
6319 (C * 8) % 4 since we know that's zero. */
6322 /* If the multiplication can overflow we cannot optimize this.
6323 ??? Until we can properly mark individual operations as
6324 not overflowing we need to treat sizetype special here as
6325 stor-layout relies on this opimization to make
6326 DECL_FIELD_BIT_OFFSET always a constant. */
6332 {
6335 }
6337 /* ... fall through ... */
6341 /* If we can extract our operation from the LHS, do so and return a
6342 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6343 do something only if the second operand is a constant. */
6357 /* If these are the same operation types, we can associate them
6358 assuming no overflow. */
6370 /* If these operations "cancel" each other, we have the main
6371 optimizations of this pass, which occur when either constant is a
6372 multiple of the other, in which case we replace this with either an
6373 operation or CODE or TCODE.
6375 If we have an unsigned type that is not a sizetype, we cannot do
6376 this since it will change the result if the original computation
6377 overflowed. */
6385 {
6387 {
6394 }
6396 {
6403 }
6404 }
6409 }
6412 }
6413 \f
6414 /* Return a node which has the indicated constant VALUE (either 0 or
6415 1), and is of the indicated TYPE. */
6417 tree
6419 {
6424 else
6426 }
6429 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6430 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6431 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6432 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6433 COND is the first argument to CODE; otherwise (as in the example
6434 given here), it is the second argument. TYPE is the type of the
6435 original expression. Return NULL_TREE if no simplification is
6436 possible. */
6438 static tree
6442 {
6449 /* This transformation is only worthwhile if we don't have to wrap
6450 arg in a SAVE_EXPR, and the operation can be simplified on at least
6451 one of the branches once its pushed inside the COND_EXPR. */
6456 {
6460 /* If this operand throws an expression, then it does not make
6461 sense to try to perform a logical or arithmetic operation
6462 involving it. */
6467 }
6468 else
6469 {
6474 }
6478 {
6482 else
6484 }
6486 {
6490 else
6492 }
6496 }
6498 \f
6499 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6501 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6502 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6503 ADDEND is the same as X.
6505 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6506 and finite. The problematic cases are when X is zero, and its mode
6507 has signed zeros. In the case of rounding towards -infinity,
6508 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6509 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6511 bool
6513 {
6517 /* Don't allow the fold with -fsignaling-nans. */
6521 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6525 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6530 /* The mode has signed zeros, and we have to honor their sign.
6531 In this situation, there is only one case we can return true for.
6532 X - 0 is the same as X unless rounding towards -infinity is
6533 supported. */
6535 }
6537 /* Subroutine of fold() that checks comparisons of built-in math
6538 functions against real constants.
6540 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6541 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6542 is the type of the result and ARG0 and ARG1 are the operands of the
6543 comparison. ARG1 must be a TREE_REAL_CST.
6545 The function returns the constant folded tree if a simplification
6546 can be made, and NULL_TREE otherwise. */
6548 static tree
6551 {
6552 REAL_VALUE_TYPE c;
6555 {
6561 {
6562 /* sqrt(x) < y is always false, if y is negative. */
6566 /* sqrt(x) > y is always true, if y is negative and we
6567 don't care about NaNs, i.e. negative values of x. */
6571 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6574 }
6576 {
6577 REAL_VALUE_TYPE c2;
6583 {
6584 /* sqrt(x) > y is x == +Inf, when y is very large. */
6589 /* sqrt(x) > y is always false, when y is very large
6590 and we don't care about infinities. */
6592 }
6594 /* sqrt(x) > c is the same as x > c*c. */
6597 }
6599 {
6600 REAL_VALUE_TYPE c2;
6606 {
6607 /* sqrt(x) < y is always true, when y is a very large
6608 value and we don't care about NaNs or Infinities. */
6612 /* sqrt(x) < y is x != +Inf when y is very large and we
6613 don't care about NaNs. */
6618 /* sqrt(x) < y is x >= 0 when y is very large and we
6619 don't care about Infinities. */
6624 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6633 dconst0)),
6636 c2)));
6637 }
6639 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6644 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6647 {
6652 dconst0)),
6655 c2)));
6656 }
6657 }
6658 }
6661 }
6663 /* Subroutine of fold() that optimizes comparisons against Infinities,
6664 either +Inf or -Inf.
6666 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6667 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6668 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6670 The function returns the constant folded tree if a simplification
6671 can be made, and NULL_TREE otherwise. */
6673 static tree
6675 {
6677 REAL_VALUE_TYPE max;
6678 tree temp;
6683 /* For negative infinity swap the sense of the comparison. */
6689 {
6691 /* x > +Inf is always false, if with ignore sNANs. */
6697 /* x <= +Inf is always true, if we don't case about NaNs. */
6701 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6704 {
6707 }
6712 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6718 /* x < +Inf is always equal to x <= DBL_MAX. */
6724 /* x != +Inf is always equal to !(x > DBL_MAX). */
6736 }
6739 }
6741 /* Subroutine of fold() that optimizes comparisons of a division by
6742 a nonzero integer constant against an integer constant, i.e.
6743 X/C1 op C2.
6745 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6746 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6747 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6749 The function returns the constant folded tree if a simplification
6750 can be made, and NULL_TREE otherwise. */
6752 static tree
6754 {
6759 HOST_WIDE_INT hpart;
6764 /* We have to do this the hard way to detect unsigned overflow.
6765 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6776 {
6781 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6789 }
6791 {
6795 {
6814 }
6815 }
6816 else
6817 {
6818 /* A negative divisor reverses the relational operators. */
6824 {
6843 }
6844 }
6847 {
6868 {
6871 }
6876 {
6879 }
6884 {
6887 }
6892 {
6895 }
6900 }
6903 }
6906 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6907 equality/inequality test, then return a simplified form of the test
6908 using a sign testing. Otherwise return NULL. TYPE is the desired
6909 result type. */
6911 static tree
6913 tree result_type)
6914 {
6915 /* If this is testing a single bit, we can optimize the test. */
6919 {
6920 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6921 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6925 /* This is only a win if casting to a signed type is cheap,
6926 i.e. when arg00's type is not a partial mode. */
6929 {
6934 }
6935 }
6938 }
6940 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6941 equality/inequality test, then return a simplified form of
6942 the test using shifts and logical operations. Otherwise return
6943 NULL. TYPE is the desired result type. */
6945 tree
6947 tree result_type)
6948 {
6949 /* If this is testing a single bit, we can optimize the test. */
6953 {
6962 /* First, see if we can fold the single bit test into a sign-bit
6963 test. */
6965 result_type);
6969 /* Otherwise we have (A & C) != 0 where C is a single bit,
6970 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6971 Similarly for (A & C) == 0. */
6973 /* If INNER is a right shift of a constant and it plus BITNUM does
6974 not overflow, adjust BITNUM and INNER. */
6981 {
6984 }
6986 /* If we are going to be able to omit the AND below, we must do our
6987 operations as unsigned. If we must use the AND, we have a choice.
6988 Normally unsigned is faster, but for some machines signed is. */
6989 #ifdef LOAD_EXTEND_OP
6992 #else
6994 #endif
7010 /* Put the AND last so it can combine with more things. */
7013 /* Make sure to return the proper type. */
7017 }
7019 }
7021 /* Check whether we are allowed to reorder operands arg0 and arg1,
7022 such that the evaluation of arg1 occurs before arg0. */
7024 static bool
7026 {
7033 }
7035 /* Test whether it is preferable two swap two operands, ARG0 and
7036 ARG1, for example because ARG0 is an integer constant and ARG1
7037 isn't. If REORDER is true, only recommend swapping if we can
7038 evaluate the operands in reverse order. */
7040 bool
7042 {
7078 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7079 for commutative and comparison operators. Ensuring a canonical
7080 form allows the optimizers to find additional redundancies without
7081 having to explicitly check for both orderings. */
7087 /* Put SSA_NAMEs last. */
7093 /* Put variables last. */
7100 }
7102 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7103 ARG0 is extended to a wider type. */
7105 static tree
7107 {
7109 tree arg1_unw;
7118 #ifdef HAVE_canonicalize_funcptr_for_compare
7119 /* Disable this optimization if we're casting a function pointer
7120 type on targets that require function pointer canonicalization. */
7125 #endif
7132 /* If possible, express the comparison in the shorter mode. */
7152 /* If we are comparing with the integer that does not fit into the range
7153 of the shorter type, the result is known. */
7164 {
7191 }
7194 }
7196 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7197 ARG0 just the signedness is changed. */
7199 static tree
7202 {
7203 tree arg0_inner;
7213 #ifdef HAVE_canonicalize_funcptr_for_compare
7214 /* Disable this optimization if we're casting a function pointer
7215 type on targets that require function pointer canonicalization. */
7220 #endif
7225 /* If the conversion is from an integral subtype to its basetype
7226 leave it alone. */
7245 else
7249 }
7251 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7252 step of the array. Reconstructs s and delta in the case of s * delta
7253 being an integer constant (and thus already folded).
7254 ADDR is the address. MULT is the multiplicative expression.
7255 If the function succeeds, the new address expression is returned. Otherwise
7256 NULL_TREE is returned. */
7258 static tree
7260 {
7264 tree itype;
7267 /* Strip the nops that might be added when converting op1 to sizetype. */
7270 /* Canonicalize op1 into a possibly non-constant delta
7271 and an INTEGER_CST s. */
7273 {
7280 {
7283 }
7285 {
7288 }
7289 else
7291 }
7293 {
7296 }
7297 else
7298 {
7299 /* Simulate we are delta * 1. */
7302 }
7305 {
7307 {
7308 /* Remember if this was a multi-dimensional array. */
7321 {
7324 }
7325 else
7326 {
7327 /* Try if delta is a multiple of step. */
7332 }
7334 /* Only fold here if we can verify we do not overflow one
7335 dimension of a multi-dimensional array. */
7337 {
7338 tree tmp;
7354 }
7357 }
7358 else
7363 }
7365 /* We found the suitable array reference. So copy everything up to it,
7366 and replace the index. */
7373 {
7377 }
7385 }
7388 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7389 means A >= Y && A != MAX, but in this case we know that
7390 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7392 static tree
7394 {
7401 else
7410 {
7413 }
7415 {
7418 }
7419 else
7426 {
7427 /* Convert the pointer types into integer before taking the difference. */
7431 }
7432 else
7439 }
7441 /* Fold a sum or difference of at least one multiplication.
7442 Returns the folded tree or NULL if no simplification could be made. */
7444 static tree
7446 {
7450 /* (A * C) +- (B * C) -> (A+-B) * C.
7451 (A * C) +- A -> A * (C+-1).
7452 We are most concerned about the case where C is a constant,
7453 but other combinations show up during loop reduction. Since
7454 it is not difficult, try all four possibilities. */
7457 {
7460 }
7462 {
7465 }
7466 else
7467 {
7468 /* We cannot generate constant 1 for fract. */
7473 }
7475 {
7478 }
7480 {
7482 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7483 the purpose of this canonicalization. */
7487 {
7490 }
7491 else
7493 }
7494 else
7495 {
7496 /* We cannot generate constant 1 for fract. */
7501 }
7513 /* No identical multiplicands; see if we can find a common
7514 power-of-two factor in non-power-of-two multiplies. This
7515 can help in multi-dimensional array access. */
7518 {
7521 tree maybe_same;
7525 /* Move min of absolute values to int11. */
7528 {
7533 }
7534 else
7538 /* The remainder should not be a constant, otherwise we
7539 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7540 increased the number of multiplications necessary. */
7542 {
7550 }
7551 }
7561 }
7563 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7564 specified by EXPR into the buffer PTR of length LEN bytes.
7565 Return the number of bytes placed in the buffer, or zero
7566 upon failure. */
7568 static int
7570 {
7581 {
7585 else
7590 {
7597 else
7599 }
7600 else
7603 }
7605 }
7608 /* Subroutine of native_encode_expr. Encode the REAL_CST
7609 specified by EXPR into the buffer PTR of length LEN bytes.
7610 Return the number of bytes placed in the buffer, or zero
7611 upon failure. */
7613 static int
7615 {
7621 /* There are always 32 bits in each long, no matter the size of
7622 the hosts long. We handle floating point representations with
7623 up to 192 bits. */
7634 {
7639 {
7646 else
7648 }
7649 else
7652 }
7654 }
7656 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7657 specified by EXPR into the buffer PTR of length LEN bytes.
7658 Return the number of bytes placed in the buffer, or zero
7659 upon failure. */
7661 static int
7663 {
7665 tree part;
7676 }
7679 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7680 specified by EXPR into the buffer PTR of length LEN bytes.
7681 Return the number of bytes placed in the buffer, or zero
7682 upon failure. */
7684 static int
7686 {
7696 {
7698 {
7701 }
7702 else
7706 {
7709 }
7710 else
7711 {
7715 }
7717 }
7719 }
7722 /* Subroutine of native_encode_expr. Encode the STRING_CST
7723 specified by EXPR into the buffer PTR of length LEN bytes.
7724 Return the number of bytes placed in the buffer, or zero
7725 upon failure. */
7727 static int
7729 {
7731 HOST_WIDE_INT total_bytes;
7742 {
7746 }
7747 else
7750 }
7753 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7754 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7755 buffer PTR of length LEN bytes. Return the number of bytes
7756 placed in the buffer, or zero upon failure. */
7758 int
7760 {
7762 {
7780 }
7781 }
7784 /* Subroutine of native_interpret_expr. Interpret the contents of
7785 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7786 If the buffer cannot be interpreted, return NULL_TREE. */
7788 static tree
7790 {
7804 {
7807 {
7814 else
7816 }
7817 else
7823 else
7826 }
7829 }
7832 /* Subroutine of native_interpret_expr. Interpret the contents of
7833 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7834 If the buffer cannot be interpreted, return NULL_TREE. */
7836 static tree
7838 {
7843 /* There are always 32 bits in each long, no matter the size of
7844 the hosts long. We handle floating point representations with
7845 up to 192 bits. */
7846 REAL_VALUE_TYPE r;
7857 {
7860 {
7867 else
7869 }
7870 else
7875 }
7879 }
7882 /* Subroutine of native_interpret_expr. Interpret the contents of
7883 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7884 If the buffer cannot be interpreted, return NULL_TREE. */
7886 static tree
7888 {
7903 }
7906 /* Subroutine of native_interpret_expr. Interpret the contents of
7907 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7908 If the buffer cannot be interpreted, return NULL_TREE. */
7910 static tree
7912 {
7924 {
7929 }
7931 }
7934 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7935 the buffer PTR of length LEN as a constant of type TYPE. For
7936 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7937 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7938 return NULL_TREE. */
7940 tree
7942 {
7944 {
7961 }
7962 }
7965 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7966 TYPE at compile-time. If we're unable to perform the conversion
7967 return NULL_TREE. */
7969 static tree
7971 {
7972 /* We support up to 512-bit values (for V8DFmode). */
7976 /* Check that the host and target are sane. */
7985 }
7987 /* Build an expression for the address of T. Folds away INDIRECT_REF
7988 to avoid confusing the gimplify process. */
7990 tree
7992 {
7993 /* The size of the object is not relevant when talking about its address. */
7997 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8000 {
8005 }
8006 else
8010 }
8012 /* Build an expression for the address of T. */
8014 tree
8016 {
8020 }
8022 /* Fold a unary expression of code CODE and type TYPE with operand
8023 OP0. Return the folded expression if folding is successful.
8024 Otherwise, return NULL_TREE. */
8026 tree
8028 {
8029 tree tem;
8030 tree arg0;
8038 {
8041 {
8042 /* Don't use STRIP_NOPS, because signedness of argument type
8043 matters. */
8045 }
8046 else
8047 {
8048 /* Strip any conversions that don't change the mode. This
8049 is safe for every expression, except for a comparison
8050 expression because its signedness is derived from its
8051 operands.
8053 Note that this is done as an internal manipulation within
8054 the constant folder, in order to find the simplest
8055 representation of the arguments so that their form can be
8056 studied. In any cases, the appropriate type conversions
8057 should be put back in the tree that will get out of the
8058 constant folder. */
8060 }
8061 }
8064 {
8071 {
8083 /* If this was a conversion, and all we did was to move into
8084 inside the COND_EXPR, bring it back out. But leave it if
8085 it is a conversion from integer to integer and the
8086 result precision is no wider than a word since such a
8087 conversion is cheap and may be optimized away by combine,
8088 while it couldn't if it were outside the COND_EXPR. Then return
8089 so we don't get into an infinite recursion loop taking the
8090 conversion out and then back in. */
8102 && (INTEGRAL_TYPE_P
8114 }
8116 {
8118 {
8122 }
8126 integer_one_node),
8128 integer_zero_node));
8129 }
8130 }
8133 {
8135 /* Re-association barriers around constants and other re-association
8136 barriers can be removed. */
8142 CASE_CONVERT:
8148 /* If we have (type) (a CMP b) and type is an integral type, return
8149 new expression involving the new type. */
8154 /* Handle cases of two conversions in a row. */
8156 {
8178 /* In addition to the cases of two conversions in a row
8179 handled below, if we are converting something to its own
8180 type via an object of identical or wider precision, neither
8181 conversion is needed. */
8188 /* Likewise, if the intermediate and initial types are either both
8189 float or both integer, we don't need the middle conversion if the
8190 former is wider than the latter and doesn't change the signedness
8191 (for integers). Avoid this if the final type is a pointer since
8192 then we sometimes need the middle conversion. Likewise if the
8193 final type has a precision not equal to the size of its mode. */
8202 && ! final_ptr
8206 /* If we have a sign-extension of a zero-extended value, we can
8207 replace that by a single zero-extension. */
8213 /* Two conversions in a row are not needed unless:
8214 - some conversion is floating-point (overstrict for now), or
8215 - some conversion is a vector (overstrict for now), or
8216 - the intermediate type is narrower than both initial and
8217 final, or
8218 - the intermediate type and innermost type differ in signedness,
8219 and the outermost type is wider than the intermediate, or
8220 - the initial type is a pointer type and the precisions of the
8221 intermediate and final types differ, or
8222 - the final type is a pointer type and the precisions of the
8223 initial and intermediate types differ. */
8237 }
8239 /* Handle (T *)&A.B.C for A being of type T and B and C
8240 living at offset zero. This occurs frequently in
8241 C++ upcasting and then accessing the base. */
8245 {
8247 tree offset;
8253 /* If the reference was to a (constant) zero offset, we can use
8254 the address of the base if it has the same base type
8255 as the result type. */
8260 }
8264 /* Detect assigning a bitfield. */
8266 && DECL_BIT_FIELD
8268 {
8269 /* Don't leave an assignment inside a conversion
8270 unless assigning a bitfield. */
8272 /* First do the assignment, then return converted constant. */
8277 }
8279 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8280 constants (if x has signed type, the sign bit cannot be set
8281 in c). This folds extension into the BIT_AND_EXPR.
8282 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8283 very likely don't have maximal range for their precision and this
8284 transformation effectively doesn't preserve non-maximal ranges. */
8288 /* Not if the conversion is to the sub-type. */
8290 {
8300 <= HOST_BITS_PER_WIDE_INT
8302 {
8309 #ifdef LOAD_EXTEND_OP
8311 && !flag_syntax_only
8314 {
8318 }
8319 #endif
8320 }
8322 {
8328 }
8329 }
8331 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8332 when one of the new casts will fold away. Conservatively we assume
8333 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8339 {
8345 }
8347 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8348 of the same precision, and X is an integer type not narrower than
8349 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8355 {
8360 }
8362 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8363 type of X and Y (integer types only). */
8368 {
8369 /* Be careful not to introduce new overflows. */
8370 tree mult_type;
8373 else
8377 {
8384 }
8385 }
8400 /* For integral conversions with the same precision or pointer
8401 conversions use a NOP_EXPR instead. */
8407 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8408 a sub-type to its base type as generated by the Ada FE. */
8413 /* Strip inner integral conversions that do not change the precision. */
8436 /* Convert fabs((double)float) into (double)fabsf(float). */
8439 {
8444 targ0));
8445 }
8446 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8452 /* Strip sign ops from argument. */
8454 {
8458 }
8465 {
8470 }
8472 {
8477 }
8487 /* Convert ~ (-A) to A - 1. */
8492 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8500 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8513 /* Perform BIT_NOT_EXPR on each element individually. */
8515 {
8520 {
8522 {
8528 }
8529 else
8532 }
8535 }
8540 /* The argument to invert_truthvalue must have Boolean type. */
8544 /* Note that the operand of this must be an int
8545 and its values must be 0 or 1.
8546 ("true" is a fixed value perhaps depending on the language,
8547 but we don't handle values other than 1 correctly yet.) */
8562 {
8570 }
8572 {
8576 }
8578 {
8582 {
8591 }
8592 }
8604 {
8612 }
8614 {
8618 }
8620 {
8624 {
8633 }
8634 }
8640 }
8643 /* If the operation was a conversion do _not_ mark a resulting constant
8644 with TREE_OVERFLOW if the original constant was not. These conversions
8645 have implementation defined behavior and retaining the TREE_OVERFLOW
8646 flag here would confuse later passes such as VRP. */
8647 tree
8649 {
8658 }
8660 /* Fold a binary expression of code CODE and type TYPE with operands
8661 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8662 Return the folded expression if folding is successful. Otherwise,
8663 return NULL_TREE. */
8665 static tree
8667 {
8674 else
8677 /* MIN (MAX (a, b), b) == b. */
8682 /* MIN (MAX (b, a), b) == b. */
8688 /* MIN (a, MAX (a, b)) == a. */
8694 /* MIN (a, MAX (b, a)) == a. */
8701 }
8703 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8704 by changing CODE to reduce the magnitude of constants involved in
8705 ARG0 of the comparison.
8706 Returns a canonicalized comparison tree if a simplification was
8707 possible, otherwise returns NULL_TREE.
8708 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8709 valid if signed overflow is undefined. */
8711 static tree
8715 {
8721 /* Match A +- CST code arg1 and CST code arg1. We can change the
8722 first form only if overflow is undefined. */
8724 /* In principle pointers also have undefined overflow behavior,
8725 but that causes problems elsewhere. */
8733 /* Identify the constant in arg0 and its sign. */
8736 else
8740 /* Overflowed constants and zero will cause problems. */
8745 /* See if we can reduce the magnitude of the constant in
8746 arg0 by changing the comparison code. */
8748 {
8749 /* CST <= arg1 -> CST-1 < arg1. */
8752 /* -CST < arg1 -> -CST-1 <= arg1. */
8755 /* CST > arg1 -> CST-1 >= arg1. */
8758 /* -CST >= arg1 -> -CST-1 > arg1. */
8761 else
8763 /* arg1 code' CST' might be more canonical. */
8765 }
8766 else
8767 {
8768 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8772 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8776 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8780 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8784 else
8787 }
8789 /* Now build the constant reduced in magnitude. But not if that
8790 would produce one outside of its types range. */
8798 /* We cannot swap the comparison here as that would cause us to
8799 endlessly recurse. */
8807 /* If swapping might yield to a more canonical form, do so. */
8810 else
8812 }
8814 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8815 overflow further. Try to decrease the magnitude of constants involved
8816 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8817 and put sole constants at the second argument position.
8818 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8820 static tree
8823 {
8824 tree t;
8829 /* Try canonicalization by simplifying arg0. */
8834 {
8838 }
8840 /* Try canonicalization by simplifying arg1 using the swapped
8841 comparison. */
8849 }
8851 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8852 space. This is used to avoid issuing overflow warnings for
8853 expressions like &p->x which can not wrap. */
8855 static bool
8857 {
8868 {
8871 }
8874 else
8875 {
8878 }
8893 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8894 array. */
8896 {
8897 HOST_WIDE_INT base_size;
8902 }
8905 }
8907 /* Subroutine of fold_binary. This routine performs all of the
8908 transformations that are common to the equality/inequality
8909 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8910 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8911 fold_binary should call fold_binary. Fold a comparison with
8912 tree code CODE and type TYPE with operands OP0 and OP1. Return
8913 the folded comparison or NULL_TREE. */
8915 static tree
8917 {
8930 /* If one arg is a real or integer constant, put it last. */
8934 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8941 {
8945 tree lhs;
8952 /* If the constant operation overflowed this can be
8953 simplified as a comparison against INT_MAX/INT_MIN. */
8956 {
8960 /* Get the sign of the constant on the lhs if the
8961 operation were VARIABLE + CONST1. */
8965 /* The sign of the constant determines if we overflowed
8966 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8967 Canonicalize to the INT_MIN overflow by swapping the comparison
8968 if necessary. */
8972 /* We now can look at the canonicalized case
8973 VARIABLE + 1 CODE2 INT_MIN
8974 and decide on the result. */
8983 }
8988 {
8990 "when changing X +- C1 cmp C2 to "
8992 WARN_STRICT_OVERFLOW_COMPARISON);
8994 }
8995 }
8997 /* For comparisons of pointers we can decompose it to a compile time
8998 comparison of the base objects and the offsets into the object.
8999 This requires at least one operand being an ADDR_EXPR or a
9000 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9006 {
9013 /* Get base and offset for the access. Strip ADDR_EXPR for
9014 get_inner_reference, but put it back by stripping INDIRECT_REF
9015 off the base object if possible. indirect_baseN will be true
9016 if baseN is not an address but refers to the object itself. */
9019 {
9025 else
9027 }
9029 {
9032 }
9036 {
9042 else
9044 }
9046 {
9049 }
9051 /* If we have equivalent bases we might be able to simplify. */
9054 {
9055 /* We can fold this expression to a constant if the non-constant
9056 offset parts are equal. */
9064 {
9071 "occur when comparing P +- C1 with "
9073 WARN_STRICT_OVERFLOW_CONDITIONAL);
9076 {
9090 }
9091 }
9092 /* We can simplify the comparison to a comparison of the variable
9093 offset parts if the constant offset parts are equal.
9094 Be careful to use signed size type here because otherwise we
9095 mess with array offsets in the wrong way. This is possible
9096 because pointer arithmetic is restricted to retain within an
9097 object and overflow on pointer differences is undefined as of
9098 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9102 {
9103 tree signed_size_type_node;
9106 /* By converting to signed size type we cover middle-end pointer
9107 arithmetic which operates on unsigned pointer types of size
9108 type size and ARRAY_REF offsets which are properly sign or
9109 zero extended from their type in case it is narrower than
9110 size type. */
9113 else
9117 else
9125 "occur when comparing P +- C1 with "
9127 WARN_STRICT_OVERFLOW_COMPARISON);
9130 }
9131 }
9132 /* For non-equal bases we can simplify if they are addresses
9133 of local binding decls or constants. */
9135 /* We know that !operand_equal_p (base0, base1, 0)
9136 because the if condition was false. But make
9137 sure two decls are not the same. */
9151 {
9156 }
9157 /* For equal offsets we can simplify to a comparison of the
9158 base addresses. */
9160 && (indirect_base0
9162 && (indirect_base1
9167 {
9173 }
9174 }
9176 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9177 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9178 the resulting offset is smaller in absolute value than the
9179 original one. */
9187 {
9192 tree cst;
9194 "occur when combining constants around "
9197 /* Put the constant on the side where it doesn't overflow and is
9198 of lower absolute value than before. */
9204 {
9207 variable1,
9210 }
9217 {
9222 variable2);
9223 }
9224 }
9226 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9227 signed arithmetic case. That form is created by the compiler
9228 often enough for folding it to be of value. One example is in
9229 computing loop trip counts after Operator Strength Reduction. */
9235 {
9244 "eliminating multiplication in comparison "
9246 WARN_STRICT_OVERFLOW_COMPARISON);
9248 /* If const1 is negative we swap the sense of the comparison. */
9253 }
9260 {
9268 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9273 /* (-a) CMP (-b) -> b CMP a */
9280 {
9281 REAL_VALUE_TYPE cst;
9284 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9291 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9292 /* a CMP (-0) -> a CMP 0 */
9297 /* x != NaN is always true, other ops are always false. */
9300 {
9303 }
9305 /* Fold comparisons against infinity. */
9308 {
9312 }
9313 }
9315 /* If this is a comparison of a real constant with a PLUS_EXPR
9316 or a MINUS_EXPR of a real constant, we can convert it into a
9317 comparison with a revised real constant as long as no overflow
9318 occurs when unsafe_math_optimizations are enabled. */
9330 /* Likewise, we can simplify a comparison of a real constant with
9331 a MINUS_EXPR whose first operand is also a real constant, i.e.
9332 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9333 floating-point types only if -fassociative-math is set. */
9344 /* Fold comparisons against built-in math functions. */
9346 && flag_unsafe_math_optimizations
9348 {
9352 {
9356 }
9357 }
9358 }
9362 {
9363 /* If we are widening one operand of an integer comparison,
9364 see if the other operand is similarly being widened. Perhaps we
9365 can do the comparison in the narrower type. */
9370 /* Or if we are changing signedness. */
9374 }
9376 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9377 constant, we can simplify it. */
9382 {
9386 }
9388 /* Simplify comparison of something with itself. (For IEEE
9389 floating-point, we can only do some of these simplifications.) */
9391 {
9393 {
9408 /* For NE, we can only do this simplification if integer
9409 or we don't honor IEEE floating point NaNs. */
9413 /* ... fall through ... */
9419 }
9420 }
9422 /* If we are comparing an expression that just has comparisons
9423 of two integer values, arithmetic expressions of those comparisons,
9424 and constants, we can simplify it. There are only three cases
9425 to check: the two values can either be equal, the first can be
9426 greater, or the second can be greater. Fold the expression for
9427 those three values. Since each value must be 0 or 1, we have
9428 eight possibilities, each of which corresponds to the constant 0
9429 or 1 or one of the six possible comparisons.
9431 This handles common cases like (a > b) == 0 but also handles
9432 expressions like ((x > y) - (y > x)) > 0, which supposedly
9433 occur in macroized code. */
9436 {
9441 /* Don't handle degenerate cases here; they should already
9442 have been handled anyway. */
9451 {
9455 /* We can't just pass T to eval_subst in case cval1 or cval2
9456 was the same as ARG1. */
9458 tree high_result
9462 arg1);
9463 tree equal_result
9467 arg1);
9468 tree low_result
9472 arg1);
9474 /* All three of these results should be 0 or 1. Confirm they are.
9475 Then use those values to select the proper code to use. */
9480 {
9481 /* Make a 3-bit mask with the high-order bit being the
9482 value for `>', the next for '=', and the low for '<'. */
9486 {
9488 /* Always false. */
9509 /* Always true. */
9511 }
9516 }
9517 }
9518 }
9520 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9521 into a single range test. */
9529 {
9533 }
9535 /* Fold ~X op ~Y as Y op X. */
9538 {
9543 }
9545 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9548 {
9554 }
9557 }
9560 /* Subroutine of fold_binary. Optimize complex multiplications of the
9561 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9562 argument EXPR represents the expression "z" of type TYPE. */
9564 static tree
9566 {
9571 {
9574 }
9576 {
9579 }
9580 else
9581 {
9585 }
9594 }
9597 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9598 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9599 guarantees that P and N have the same least significant log2(M) bits.
9600 N is not otherwise constrained. In particular, N is not normalized to
9601 0 <= N < M as is common. In general, the precise value of P is unknown.
9602 M is chosen as large as possible such that constant N can be determined.
9604 Returns M and sets *RESIDUE to N.
9606 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9607 account. This is not always possible due to PR 35705.
9608 */
9610 static unsigned HOST_WIDE_INT
9613 {
9620 {
9623 {
9625 tree offset;
9633 {
9636 else
9637 /* We don't handle more complicated offset expressions. */
9639 }
9640 }
9645 }
9647 {
9655 allow_func_align);
9661 {
9664 }
9666 {
9669 {
9672 /* Compute the greatest power-of-2 divisor of op1. */
9676 /* If align is non-zero and less than *modulus, replace
9677 *modulus with align., If align is 0, then either op1 is 0
9678 or the greatest power-of-2 divisor of op1 doesn't fit in an
9679 unsigned HOST_WIDE_INT. In either case, no additional
9680 constraint is imposed. */
9685 }
9686 }
9687 }
9689 /* If we get here, we were unable to determine anything useful about the
9690 expression. */
9692 }
9695 /* Fold a binary expression of code CODE and type TYPE with operands
9696 OP0 and OP1. Return the folded expression if folding is
9697 successful. Otherwise, return NULL_TREE. */
9699 tree
9701 {
9715 /* Strip any conversions that don't change the mode. This is
9716 safe for every expression, except for a comparison expression
9717 because its signedness is derived from its operands. So, in
9718 the latter case, only strip conversions that don't change the
9719 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9720 preserved.
9722 Note that this is done as an internal manipulation within the
9723 constant folder, in order to find the simplest representation
9724 of the arguments so that their form can be studied. In any
9725 cases, the appropriate type conversions should be put back in
9726 the tree that will get out of the constant folder. */
9729 {
9732 }
9733 else
9734 {
9737 }
9739 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9740 constant but we can't do arithmetic on them. */
9747 {
9749 {
9750 /* Make sure type and arg0 have the same saturating flag. */
9754 }
9757 else
9761 {
9765 }
9766 }
9768 /* If this is a commutative operation, and ARG0 is a constant, move it
9769 to ARG1 to reduce the number of tests below. */
9774 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9776 First check for cases where an arithmetic operation is applied to a
9777 compound, conditional, or comparison operation. Push the arithmetic
9778 operation inside the compound or conditional to see if any folding
9779 can then be done. Convert comparison to conditional for this purpose.
9780 The also optimizes non-constant cases that used to be done in
9781 expand_expr.
9783 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9784 one of the operands is a comparison and the other is a comparison, a
9785 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9786 code below would make the expression more complex. Change it to a
9787 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9788 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9800 {
9804 boolean_type_node,
9812 }
9816 {
9822 op1));
9831 {
9837 }
9840 {
9846 }
9847 }
9850 {
9852 /* 0 +p index -> (type)index */
9856 /* PTR +p 0 -> PTR */
9860 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9867 /* index +p PTR -> PTR +p index */
9874 /* (PTR +p B) +p A -> PTR +p (B + A) */
9876 {
9877 tree inner;
9885 }
9887 /* PTR_CST +p CST -> CST1 */
9891 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9892 of the array. Loop optimizer sometimes produce this type of
9893 expressions. */
9895 {
9899 }
9904 /* A + (-B) -> A - B */
9909 /* (-A) + B -> B - A */
9917 {
9918 /* Convert ~A + 1 to -A. */
9924 /* ~X + X is -1. */
9927 {
9932 {
9935 }
9936 }
9938 /* X + ~X is -1. */
9941 {
9946 {
9949 }
9950 }
9952 /* X + (X / CST) * -CST is X % CST. */
9957 {
9965 }
9966 }
9968 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9969 same or one. Make sure type is not saturating.
9970 fold_plusminus_mult_expr will re-associate. */
9975 {
9979 }
9982 {
9986 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9987 with a constant, and the two constants have no bits in common,
9988 we should treat this as a BIT_IOR_EXPR since this may produce more
9989 simplifications. */
9997 {
10000 }
10002 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10003 (plus (plus (mult) (mult)) (foo)) so that we can
10004 take advantage of the factoring cases below. */
10011 {
10017 else
10039 parg1)));
10040 }
10041 }
10042 else
10043 {
10044 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10048 /* Likewise if the operands are reversed. */
10052 /* Convert X + -C into X - C. */
10055 {
10061 }
10063 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10064 to __complex__ ( x, y ). This is not the same for SNaNs or
10065 if signed zeros are involved. */
10069 {
10076 {
10080 {
10086 }
10088 {
10094 }
10095 }
10096 }
10104 /* Convert x+x into x*2.0. */
10110 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10111 We associate floats only if the user has specified
10112 -fassociative-math. */
10116 {
10121 {
10122 tree tree0;
10125 }
10126 }
10127 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10128 We associate floats only if the user has specified
10129 -fassociative-math. */
10133 {
10138 {
10139 tree tree0;
10142 }
10143 }
10144 }
10146 bit_rotate:
10147 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10148 is a rotate of A by C1 bits. */
10149 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10150 is a rotate of A by B bits. */
10151 {
10153 tree rtype;
10162 /* Only create rotates in complete modes. Other cases are not
10163 expanded properly. */
10165 {
10184 {
10192 TYPE_PRECISION
10197 ? LROTATE_EXPR
10200 }
10202 {
10210 TYPE_PRECISION
10215 ? LROTATE_EXPR
10218 }
10219 }
10220 }
10222 associate:
10223 /* In most languages, can't associate operations on floats through
10224 parentheses. Rather than remember where the parentheses were, we
10225 don't associate floats at all, unless the user has specified
10226 -fassociative-math.
10227 And, we need to make sure type is not saturating. */
10231 {
10236 /* Split both trees into variables, constants, and literals. Then
10237 associate each group together, the constants with literals,
10238 then the result with variables. This increases the chances of
10239 literals being recombined later and of generating relocatable
10240 expressions for the sum of a constant and literal. */
10245 /* With undefined overflow we can only associate constants
10246 with one variable. */
10250 {
10258 /* The only case we can still associate with two variables
10259 is if they are the same, modulo negation. */
10262 }
10264 /* Only do something if we found more than two objects. Otherwise,
10265 nothing has changed and we risk infinite recursion. */
10271 {
10272 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10281 /* Preserve the MINUS_EXPR if the negative part of the literal is
10282 greater than the positive part. Otherwise, the multiplicative
10283 folding code (i.e extract_muldiv) may be fooled in case
10284 unsigned constants are subtracted, like in the following
10285 example: ((X*2 + 4) - 8U)/2. */
10287 {
10291 {
10295 }
10296 else
10297 {
10301 }
10302 }
10304 {
10309 else
10310 {
10316 }
10317 }
10322 }
10323 }
10328 /* Pointer simplifications for subtraction, simple reassociations. */
10330 {
10331 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10334 {
10342 }
10343 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10345 {
10351 }
10352 }
10353 /* A - (-B) -> A + B */
10357 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10366 /* Convert -A - 1 to ~A. */
10374 /* Convert -1 - A to ~A. */
10380 /* X - (X / CST) * CST is X % CST. */
10393 {
10399 /* Fold A - (A & B) into ~B & A. */
10402 {
10404 {
10409 }
10411 {
10416 }
10417 }
10419 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10420 any power of 2 minus 1. */
10425 {
10431 {
10435 }
10436 }
10437 }
10439 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10443 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10444 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10445 (-ARG1 + ARG0) reduces to -ARG1. */
10449 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10450 __complex__ ( x, -y ). This is not the same for SNaNs or if
10451 signed zeros are involved. */
10455 {
10462 {
10466 {
10468 arg1r ? arg1r
10473 }
10475 {
10479 arg1i ? arg1i
10482 }
10483 }
10484 }
10486 /* Fold &x - &x. This can happen from &x.foo - &x.
10487 This is unsafe for certain floats even in non-IEEE formats.
10488 In IEEE, it is unsafe because it does wrong for NaNs.
10489 Also note that operand_equal_p is always false if an operand
10490 is volatile. */
10496 /* A - B -> A + (-B) if B is easily negatable. */
10499 /* Avoid this transformation if B is a positive REAL_CST. */
10507 /* Try folding difference of addresses. */
10508 {
10509 HOST_WIDE_INT diff;
10515 }
10517 /* Fold &a[i] - &a[j] to i-j. */
10522 {
10527 {
10535 }
10536 }
10544 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10545 same or one. Make sure type is not saturating.
10546 fold_plusminus_mult_expr will re-associate. */
10551 {
10555 }
10560 /* (-A) * (-B) -> A * B */
10571 {
10576 /* Transform x * -1 into -x. Make sure to do the negation
10577 on the original operand with conversions not stripped
10578 because we can only strip non-sign-changing conversions. */
10581 /* Transform x * -C into -x * C if x is easily negatable. */
10590 /* (a * (1 << b)) is (a << b) */
10600 /* (A + A) * C -> A * 2 * C */
10615 {
10618 "occur when simplifying "
10620 WARN_STRICT_OVERFLOW_MISC);
10622 }
10624 /* Optimize z * conj(z) for integer complex numbers. */
10631 }
10632 else
10633 {
10634 /* Maybe fold x * 0 to 0. The expressions aren't the same
10635 when x is NaN, since x * 0 is also NaN. Nor are they the
10636 same in modes with signed zeros, since multiplying a
10637 negative value by 0 gives -0, not +0. */
10642 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10647 /* Transform x * -1.0 into -x. */
10652 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10653 the result for floating point types due to rounding so it is applied
10654 only if -fassociative-math was specify. */
10659 {
10665 }
10667 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10669 {
10672 {
10675 }
10676 }
10678 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10679 This is not the same for NaNs or if signed zeros are
10680 involved. */
10686 {
10698 }
10700 /* Optimize z * conj(z) for floating point complex numbers.
10701 Guarded by flag_unsafe_math_optimizations as non-finite
10702 imaginary components don't produce scalar results. */
10713 {
10717 /* Optimizations of root(...)*root(...). */
10719 {
10724 /* Optimize sqrt(x)*sqrt(x) as x. */
10730 /* Optimize root(x)*root(y) as root(x*y). */
10734 }
10736 /* Optimize expN(x)*expN(y) as expN(x+y). */
10738 {
10744 }
10746 /* Optimizations of pow(...)*pow(...). */
10750 {
10756 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10758 {
10762 }
10764 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10766 {
10770 }
10771 }
10773 /* Optimize tan(x)*cos(x) as sin(x). */
10782 {
10787 }
10789 /* Optimize x*pow(x,c) as pow(x,c+1). */
10793 {
10799 {
10801 REAL_VALUE_TYPE c;
10802 tree arg;
10808 }
10809 }
10811 /* Optimize pow(x,c)*x as pow(x,c+1). */
10815 {
10821 {
10823 REAL_VALUE_TYPE c;
10824 tree arg;
10830 }
10831 }
10833 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10836 {
10840 {
10843 }
10844 }
10845 }
10846 }
10850 bit_ior:
10858 /* ~X | X is -1. */
10861 {
10865 }
10867 /* X | ~X is -1. */
10870 {
10874 }
10876 /* Canonicalize (X & C1) | C2. */
10880 {
10888 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10893 {
10897 }
10898 else
10899 {
10903 }
10905 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10910 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10911 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10912 mode which allows further optimizations. */
10922 {
10923 unsigned HOST_WIDE_INT mask
10927 {
10931 }
10932 }
10939 arg1);
10940 }
10942 /* (X & Y) | Y is (X, Y). */
10946 /* (X & Y) | X is (Y, X). */
10951 /* X | (X & Y) is (Y, X). */
10956 /* X | (Y & X) is (Y, X). */
10966 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10968 This results in more efficient code for machines without a NAND
10969 instruction. Combine will canonicalize to the first form
10970 which will allow use of NAND instructions provided by the
10971 backend if they exist. */
10974 {
10981 }
10983 /* See if this can be simplified into a rotate first. If that
10984 is unsuccessful continue in the association code. */
10995 /* ~X ^ X is -1. */
10998 {
11002 }
11004 /* X ^ ~X is -1. */
11007 {
11011 }
11013 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11014 with a constant, and the two constants have no bits in common,
11015 we should treat this as a BIT_IOR_EXPR since this may produce more
11016 simplifications. */
11024 {
11027 }
11029 /* (X | Y) ^ X -> Y & ~ X*/
11032 {
11035 arg1);
11039 }
11041 /* (Y | X) ^ X -> Y & ~ X*/
11044 {
11047 arg1);
11051 }
11053 /* X ^ (X | Y) -> Y & ~ X*/
11056 {
11059 arg0);
11063 }
11065 /* X ^ (Y | X) -> Y & ~ X*/
11068 {
11071 arg0);
11075 }
11077 /* Convert ~X ^ ~Y to X ^ Y. */
11084 /* Convert ~X ^ C to X ^ ~C. */
11091 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11098 /* Fold (X & Y) ^ Y as ~X & Y. */
11101 {
11106 }
11107 /* Fold (X & Y) ^ X as ~Y & X. */
11111 {
11116 }
11117 /* Fold X ^ (X & Y) as X & ~Y. */
11120 {
11125 }
11126 /* Fold X ^ (Y & X) as ~Y & X. */
11130 {
11135 }
11137 /* See if this can be simplified into a rotate first. If that
11138 is unsuccessful continue in the association code. */
11149 /* ~X & X is always zero. */
11154 /* X & ~X is always zero. */
11159 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11163 {
11171 }
11173 /* (X | Y) & Y is (X, Y). */
11177 /* (X | Y) & X is (Y, X). */
11182 /* X & (X | Y) is (Y, X). */
11187 /* X & (Y | X) is (Y, X). */
11193 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11197 {
11203 }
11204 /* Fold ~X & 1 as (X & 1) == 0. */
11207 {
11213 }
11215 /* Fold (X ^ Y) & Y as ~X & Y. */
11218 {
11223 }
11224 /* Fold (X ^ Y) & X as ~Y & X. */
11228 {
11233 }
11234 /* Fold X & (X ^ Y) as X & ~Y. */
11237 {
11242 }
11243 /* Fold X & (Y ^ X) as ~Y & X. */
11247 {
11252 }
11257 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11260 {
11261 unsigned int prec
11268 }
11270 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11272 This results in more efficient code for machines without a NOR
11273 instruction. Combine will canonicalize to the first form
11274 which will allow use of NOR instructions provided by the
11275 backend if they exist. */
11278 {
11285 }
11287 /* If arg0 is derived from the address of an object or function, we may
11288 be able to fold this expression using the object or function's
11289 alignment. */
11291 {
11298 /* This works because modulus is a power of 2. If this weren't the
11299 case, we'd have to replace it by its greatest power-of-2
11300 divisor: modulus & -modulus. */
11303 }
11305 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11306 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11307 if the new mask might be further optimized. */
11316 {
11318 unsigned HOST_WIDE_INT mask
11328 {
11331 /* See if more bits can be proven as zero because of
11332 zero extension. */
11335 {
11340 {
11342 /* See if we can shorten the right shift. */
11345 }
11346 }
11350 /* For arithmetic shift if sign bit could be set, zerobits
11351 can contain actually sign bits, so no transformation is
11352 possible, unless MASK masks them all away. In that
11353 case the shift needs to be converted into logical shift. */
11356 {
11359 else
11361 }
11362 }
11364 /* ((X << 16) & 0xff00) is (X, 0). */
11370 {
11373 /* Only do the transformation if NEWMASK is some integer
11374 mode's mask. */
11381 {
11383 {
11389 }
11390 else
11394 newmask));
11395 }
11396 }
11397 }
11402 /* Don't touch a floating-point divide by zero unless the mode
11403 of the constant can represent infinity. */
11409 /* Optimize A / A to 1.0 if we don't care about
11410 NaNs or Infinities. Skip the transformation
11411 for non-real operands. */
11416 {
11420 }
11422 /* The complex version of the above A / A optimization. */
11425 {
11429 {
11431 /* omit_two_operands will call fold_convert for us. */
11433 }
11434 }
11436 /* (-A) / (-B) -> A / B */
11446 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11451 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11456 /* If ARG1 is a constant, we can convert this to a multiply by the
11457 reciprocal. This does not have the same rounding properties,
11458 so only do this if -freciprocal-math. We can actually
11459 always safely do it if ARG1 is a power of two, but it's hard to
11460 tell if it is or not in a portable manner. */
11462 {
11467 /* Find the reciprocal if optimizing and the result is exact. */
11469 {
11470 REAL_VALUE_TYPE r;
11473 {
11477 }
11478 }
11479 }
11480 /* Convert A/B/C to A/(B*C). */
11487 /* Convert A/(B/C) to (A/B)*C. */
11495 /* Convert C1/(X*C2) into (C1/C2)/X. */
11500 {
11506 }
11509 {
11513 /* Optimize sin(x)/cos(x) as tan(x). */
11519 {
11524 }
11526 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11532 {
11536 {
11540 }
11541 }
11543 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11544 NaNs or Infinities. */
11548 {
11555 {
11560 }
11561 }
11563 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11564 NaNs or Infinities. */
11568 {
11575 {
11579 {
11583 tmp);
11584 }
11585 }
11586 }
11588 /* Optimize pow(x,c)/x as pow(x,c-1). */
11592 {
11598 {
11600 REAL_VALUE_TYPE c;
11601 tree arg;
11607 }
11608 }
11610 /* Optimize a/root(b/c) into a*root(c/b). */
11612 {
11616 {
11625 }
11626 }
11628 /* Optimize x/expN(y) into x*expN(-y). */
11630 {
11635 }
11637 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11641 {
11648 }
11649 }
11654 /* Simplify A / (B << N) where A and B are positive and B is
11655 a power of 2, to A >> (N + log2(B)). */
11660 {
11663 {
11670 WARN_STRICT_OVERFLOW_MISC);
11676 }
11677 }
11679 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11680 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11686 /* Fall thru */
11695 /* X / -1 is -X. */
11702 /* Convert -A / -B to A / B when the type is signed and overflow is
11703 undefined. */
11707 {
11710 "when distributing negation across "
11712 WARN_STRICT_OVERFLOW_MISC);
11716 }
11720 {
11723 "when distributing negation across "
11725 WARN_STRICT_OVERFLOW_MISC);
11729 }
11731 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11732 operation, EXACT_DIV_EXPR.
11734 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11735 At one time others generated faster code, it's not clear if they do
11736 after the last round to changes to the DIV code in expmed.c. */
11745 {
11749 WARN_STRICT_OVERFLOW_MISC);
11751 }
11759 /* X % 1 is always zero, but be sure to preserve any side
11760 effects in X. */
11764 /* X % 0, return X % 0 unchanged so that we can get the
11765 proper warnings and errors. */
11769 /* 0 % X is always zero, but be sure to preserve any side
11770 effects in X. Place this after checking for X == 0. */
11774 /* X % -1 is zero. */
11781 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11782 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11787 {
11789 /* Also optimize A % (C << N) where C is a power of 2,
11790 to A & ((C << N) - 1). */
11795 {
11800 "occur when simplifying "
11802 WARN_STRICT_OVERFLOW_MISC);
11806 }
11807 }
11809 /* X % -C is the same as X % C. */
11816 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11821 /* X % -Y is the same as X % Y. */
11832 {
11836 WARN_STRICT_OVERFLOW_MISC);
11838 }
11849 /* Optimize -1 >> x for arithmetic right shifts. */
11853 /* ... fall through ... */
11856 shift:
11862 /* Since negative shift count is not well-defined,
11863 don't try to compute it in the compiler. */
11867 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11872 {
11876 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11877 being well defined. */
11879 {
11884 else
11886 }
11890 }
11892 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11893 into x & ((unsigned)-1 >> c) for unsigned types. */
11901 {
11904 tree lshift;
11905 tree arg00;
11908 {
11915 }
11916 }
11918 /* Rewrite an LROTATE_EXPR by a constant into an
11919 RROTATE_EXPR by a new constant. */
11921 {
11926 }
11928 /* If we have a rotate of a bit operation with the rotate count and
11929 the second operand of the bit operation both constant,
11930 permute the two operations. */
11942 /* Two consecutive rotates adding up to the precision of the
11943 type can be ignored. */
11954 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11955 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11956 if the latter can be further optimized. */
11961 {
11964 arg1);
11967 arg1);
11971 }
11999 /* Note that the operands of this must be ints
12000 and their values must be 0 or 1.
12001 ("true" is a fixed value perhaps depending on the language.) */
12002 /* If first arg is constant zero, return it. */
12006 /* If either arg is constant true, drop it. */
12010 /* Preserve sequence points. */
12013 /* If second arg is constant zero, result is zero, but first arg
12014 must be evaluated. */
12017 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12018 case will be handled here. */
12022 /* !X && X is always false. */
12026 /* X && !X is always false. */
12031 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12032 means A >= Y && A != MAX, but in this case we know that
12033 A < X <= MAX. */
12037 {
12045 }
12047 truth_andor:
12048 /* We only do these simplifications if we are optimizing. */
12052 /* Check for things like (A || B) && (A || C). We can convert this
12053 to A || (B && C). Note that either operator can be any of the four
12054 truth and/or operations and the transformation will still be
12055 valid. Also note that we only care about order for the
12056 ANDIF and ORIF operators. If B contains side effects, this
12057 might change the truth-value of A. */
12064 {
12084 /* This case if tricky because we must either have commutative
12085 operators or else A10 must not have side-effects. */
12091 a01);
12092 }
12094 /* See if we can build a range comparison. */
12098 /* Check for the possibility of merging component references. If our
12099 lhs is another similar operation, try to merge its rhs with our
12100 rhs. Then try to merge our lhs and rhs. */
12112 /* Note that the operands of this must be ints
12113 and their values must be 0 or true.
12114 ("true" is a fixed value perhaps depending on the language.) */
12115 /* If first arg is constant true, return it. */
12119 /* If either arg is constant zero, drop it. */
12123 /* Preserve sequence points. */
12126 /* If second arg is constant true, result is true, but we must
12127 evaluate first arg. */
12130 /* Likewise for first arg, but note this only occurs here for
12131 TRUTH_OR_EXPR. */
12135 /* !X || X is always true. */
12139 /* X || !X is always true. */
12147 /* If the second arg is constant zero, drop it. */
12150 /* If the second arg is constant true, this is a logical inversion. */
12152 {
12153 /* Only call invert_truthvalue if operand is a truth value. */
12156 else
12159 }
12160 /* Identical arguments cancel to zero. */
12164 /* !X ^ X is always true. */
12169 /* X ^ !X is always true. */
12182 /* bool_var != 0 becomes bool_var. */
12187 /* bool_var == 1 becomes bool_var. */
12192 /* bool_var != 1 becomes !bool_var. */
12197 /* bool_var == 0 becomes !bool_var. */
12202 /* If this is an equality comparison of the address of two non-weak,
12203 unaliased symbols neither of which are extern (since we do not
12204 have access to attributes for externs), then we know the result. */
12217 {
12218 /* We know that we're looking at the address of two
12219 non-weak, unaliased, static _DECL nodes.
12221 It is both wasteful and incorrect to call operand_equal_p
12222 to compare the two ADDR_EXPR nodes. It is wasteful in that
12223 all we need to do is test pointer equality for the arguments
12224 to the two ADDR_EXPR nodes. It is incorrect to use
12225 operand_equal_p as that function is NOT equivalent to a
12226 C equality test. It can in fact return false for two
12227 objects which would test as equal using the C equality
12228 operator. */
12232 type);
12233 }
12235 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12236 a MINUS_EXPR of a constant, we can convert it into a comparison with
12237 a revised constant as long as no overflow occurs. */
12249 /* Similarly for a NEGATE_EXPR. */
12257 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12266 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12273 {
12277 val,
12281 }
12283 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12288 {
12290 code == NE_EXPR
12293 }
12295 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12296 for !=. Don't do this for ordered comparisons due to overflow. */
12302 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12307 /* If this is an EQ or NE comparison with zero and ARG0 is
12308 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12309 two operations, but the latter can be done in one less insn
12310 on machines that have only two-operand insns or on which a
12311 constant cannot be the first operand. */
12314 {
12319 {
12326 }
12329 {
12336 }
12337 }
12339 /* If this is an NE or EQ comparison of zero against the result of a
12340 signed MOD operation whose second operand is a power of 2, make
12341 the MOD operation unsigned since it is simpler and equivalent. */
12349 {
12359 }
12361 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12362 C1 is a valid shift constant, and C2 is a power of two, i.e.
12363 a single bit. */
12367 == INTEGER_CST
12370 {
12375 /* Check for a valid shift count. */
12378 {
12382 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12383 can be rewritten as (X & (C2 << C1)) != 0. */
12385 {
12389 }
12390 /* Otherwise, for signed (arithmetic) shifts,
12391 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12392 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12396 /* Otherwise, of unsigned (logical) shifts,
12397 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12398 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12399 else
12403 arg000);
12404 }
12405 }
12407 /* If this is an NE comparison of zero with an AND of one, remove the
12408 comparison since the AND will give the correct value. */
12415 /* If we have (A & C) == C where C is a power of 2, convert this into
12416 (A & C) != 0. Similarly for NE_EXPR. */
12422 integer_zero_node));
12424 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12425 bit, then fold the expression into A < 0 or A >= 0. */
12430 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12431 Similarly for NE_EXPR. */
12435 {
12444 }
12446 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12447 Similarly for NE_EXPR. */
12451 {
12458 }
12460 /* If this is a comparison of a field, we may be able to simplify it. */
12463 /* Handle the constant case even without -O
12464 to make sure the warnings are given. */
12466 {
12470 }
12472 /* Optimize comparisons of strlen vs zero to a compare of the
12473 first character of the string vs zero. To wit,
12474 strlen(ptr) == 0 => *ptr == 0
12475 strlen(ptr) != 0 => *ptr != 0
12476 Other cases should reduce to one of these two (or a constant)
12477 due to the return value of strlen being unsigned. */
12480 {
12488 {
12492 }
12493 }
12495 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12496 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12500 {
12507 {
12509 {
12512 }
12515 }
12516 }
12518 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12524 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12529 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12536 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12544 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12545 (X & C) == 0 when C is a single bit. */
12550 {
12556 }
12558 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12559 constant C is a power of two, i.e. a single bit. */
12566 {
12570 }
12572 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12573 when is C is a power of two, i.e. a single bit. */
12580 {
12586 }
12590 {
12593 }
12595 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12602 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12605 {
12617 arg01),
12625 arg01),
12633 arg00),
12641 arg00),
12643 }
12647 {
12654 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12655 operand_equal_p guarantees no side-effects so we don't need
12656 to use omit_one_operand on Z. */
12666 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12673 arg10);
12674 }
12676 /* Attempt to simplify equality/inequality comparisons of complex
12677 values. Only lower the comparison if the result is known or
12678 can be simplified to a single scalar comparison. */
12683 {
12688 {
12691 }
12692 else
12693 {
12696 }
12699 {
12702 }
12703 else
12704 {
12707 }
12711 {
12713 {
12718 }
12719 else
12720 {
12725 }
12726 }
12730 {
12732 {
12737 }
12738 else
12739 {
12744 }
12745 }
12746 }
12758 /* Transform comparisons of the form X +- C CMP X. */
12765 {
12772 else
12775 /* (X - c) > X becomes false. */
12779 {
12783 "occur when assuming that (X - c) > X "
12785 WARN_STRICT_OVERFLOW_ALL);
12787 }
12789 /* Likewise (X + c) < X becomes false. */
12793 {
12797 "occur when assuming that "
12799 WARN_STRICT_OVERFLOW_ALL);
12801 }
12803 /* Convert (X - c) <= X to true. */
12808 {
12812 "occur when assuming that "
12814 WARN_STRICT_OVERFLOW_ALL);
12816 }
12818 /* Convert (X + c) >= X to true. */
12823 {
12827 "occur when assuming that "
12829 WARN_STRICT_OVERFLOW_ALL);
12831 }
12834 {
12835 /* Convert X + c > X and X - c < X to true for integers. */
12839 {
12842 "not occur when assuming that "
12844 WARN_STRICT_OVERFLOW_ALL);
12846 }
12851 {
12854 "not occur when assuming that "
12856 WARN_STRICT_OVERFLOW_ALL);
12858 }
12860 /* Convert X + c <= X and X - c >= X to false for integers. */
12864 {
12867 "not occur when assuming that "
12869 WARN_STRICT_OVERFLOW_ALL);
12871 }
12876 {
12879 "not occur when assuming that "
12881 WARN_STRICT_OVERFLOW_ALL);
12883 }
12884 }
12885 }
12887 /* Comparisons with the highest or lowest possible integer of
12888 the specified precision will have known values. */
12889 {
12896 {
12897 HOST_WIDE_INT signed_max_hi;
12902 {
12909 {
12913 }
12914 else
12915 {
12919 }
12920 }
12921 else
12922 {
12931 {
12934 }
12935 else
12936 {
12939 }
12940 }
12945 {
12958 /* The GE_EXPR and LT_EXPR cases above are not normally
12959 reached because of previous transformations. */
12963 }
12965 == max_hi
12968 {
12974 arg1);
12980 arg1);
12983 }
12985 == min_hi
12988 {
13003 }
13005 == min_hi
13008 {
13013 arg1);
13018 arg1);
13021 }
13026 /* We will flip the signedness of the comparison operator
13027 associated with the mode of arg1, so the sign bit is
13028 specified by this mode. Check that arg1 is the signed
13029 max associated with this sign bit. */
13031 /* signed_type does not work on pointer types. */
13033 {
13034 /* The following case also applies to X < signed_max+1
13035 and X >= signed_max+1 because previous transformations. */
13037 {
13038 tree st;
13043 }
13044 }
13045 }
13046 }
13048 /* If we are comparing an ABS_EXPR with a constant, we can
13049 convert all the cases into explicit comparisons, but they may
13050 well not be faster than doing the ABS and one comparison.
13051 But ABS (X) <= C is a range comparison, which becomes a subtraction
13052 and a comparison, and is probably faster. */
13066 /* Convert ABS_EXPR<x> >= 0 to true. */
13073 {
13076 "when simplifying comparison of "
13078 WARN_STRICT_OVERFLOW_CONDITIONAL);
13080 }
13082 /* Convert ABS_EXPR<x> < 0 to false. */
13087 {
13090 "when simplifying comparison of "
13092 WARN_STRICT_OVERFLOW_CONDITIONAL);
13094 }
13096 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13097 and similarly for >= into !=. */
13112 return
13131 {
13135 }
13137 /* If the first operand is NaN, the result is constant. */
13141 {
13143 ? integer_zero_node
13146 }
13148 /* If the second operand is NaN, the result is constant. */
13152 {
13154 ? integer_zero_node
13157 }
13159 /* Simplify unordered comparison of something with itself. */
13165 && !flag_trapping_math
13169 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13170 {
13181 }
13186 /* When pedantic, a compound expression can be neither an lvalue
13187 nor an integer constant expression. */
13190 /* Don't let (0, 0) be null pointer constant. */
13204 /* An ASSERT_EXPR should never be passed to fold_binary. */
13210 }
13212 /* Callback for walk_tree, looking for LABEL_EXPR.
13213 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13214 Do not check the sub-tree of GOTO_EXPR. */
13216 static tree
13220 {
13222 {
13227 /* no break */
13230 }
13231 }
13233 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13234 accessible from outside the sub-tree. Returns NULL_TREE if no
13235 addressable label is found. */
13237 static bool
13239 {
13241 }
13243 /* Fold a ternary expression of code CODE and type TYPE with operands
13244 OP0, OP1, and OP2. Return the folded expression if folding is
13245 successful. Otherwise, return NULL_TREE. */
13247 tree
13249 {
13250 tree tem;
13257 /* Strip any conversions that don't change the mode. This is safe
13258 for every expression, except for a comparison expression because
13259 its signedness is derived from its operands. So, in the latter
13260 case, only strip conversions that don't change the signedness.
13262 Note that this is done as an internal manipulation within the
13263 constant folder, in order to find the simplest representation of
13264 the arguments so that their form can be studied. In any cases,
13265 the appropriate type conversions should be put back in the tree
13266 that will get out of the constant folder. */
13268 {
13271 }
13274 {
13277 }
13280 {
13284 {
13290 }
13294 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13295 so all simple results must be passed through pedantic_non_lvalue. */
13297 {
13300 /* Only optimize constant conditions when the selected branch
13301 has the same type as the COND_EXPR. This avoids optimizing
13302 away "c ? x : throw", where the throw has a void type.
13303 Avoid throwing away that operand which contains label. */
13310 }
13314 /* If we have A op B ? A : C, we may be able to convert this to a
13315 simpler expression, depending on the operation and the values
13316 of B and C. Signed zeros prevent all of these transformations,
13317 for reasons given above each one.
13319 Also try swapping the arguments and inverting the conditional. */
13324 {
13328 }
13332 op2,
13335 {
13338 {
13342 }
13343 }
13345 /* If the second operand is simpler than the third, swap them
13346 since that produces better jump optimization results. */
13349 {
13350 /* See if this can be inverted. If it can't, possibly because
13351 it was a floating-point inequality comparison, don't do
13352 anything. */
13356 }
13358 /* Convert A ? 1 : 0 to simply A. */
13361 /* If we try to convert OP0 to our type, the
13362 call to fold will try to move the conversion inside
13363 a COND, which will recurse. In that case, the COND_EXPR
13364 is probably the best choice, so leave it alone. */
13368 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13369 over COND_EXPR in cases such as floating point comparisons. */
13376 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13381 {
13382 /* sign_bit_p only checks ARG1 bits within A's precision.
13383 If <sign bit of A> has wider type than A, bits outside
13384 of A's precision in <sign bit of A> need to be checked.
13385 If they are all 0, this optimization needs to be done
13386 in unsigned A's type, if they are all 1 in signed A's type,
13387 otherwise this can't be done. */
13392 {
13394 HOST_WIDE_INT mask_hi;
13396 tree tem_type;
13404 {
13408 }
13409 else
13410 {
13414 }
13416 {
13420 }
13421 else
13427 {
13430 }
13433 {
13436 }
13437 else
13439 }
13446 arg1)));
13447 }
13449 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13450 already handled above. */
13455 {
13464 }
13466 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13467 is probably obsolete because the first operand should be a
13468 truth value (that's why we have the two cases above), but let's
13469 leave it in until we can confirm this for all front-ends. */
13480 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13486 arg1);
13488 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13492 {
13493 /* Only perform transformation if ARG0 is easily inverted. */
13498 arg1);
13499 }
13501 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13505 {
13506 /* Only perform transformation if ARG0 is easily inverted. */
13511 op2);
13512 }
13514 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13520 op2);
13525 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13526 of fold_ternary on them. */
13533 {
13542 {
13547 else
13548 {
13550 tree value;
13554 }
13559 else
13561 }
13562 }
13564 /* A bit-field-ref that referenced the full argument can be stripped. */
13575 }
13577 /* Perform constant folding and related simplification of EXPR.
13578 The related simplifications include x*1 => x, x*0 => 0, etc.,
13579 and application of the associative law.
13580 NOP_EXPR conversions may be removed freely (as long as we
13581 are careful not to change the type of the overall expression).
13582 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13583 but we can constant-fold them if they have constant operands. */
13585 #ifdef ENABLE_FOLD_CHECKING
13586 # define fold(x) fold_1 (x)
13588 static
13589 #endif
13590 tree
13592 {
13596 tree tem;
13598 /* Return right away if a constant. */
13602 /* CALL_EXPR-like objects with variable numbers of operands are
13603 treated specially. */
13605 {
13607 {
13610 }
13612 }
13615 {
13620 {
13638 }
13639 }
13642 {
13644 {
13651 {
13656 /* Find a matching index by means of a binary search. */
13658 {
13674 else
13676 }
13677 }
13680 }
13688 }
13690 #ifdef ENABLE_FOLD_CHECKING
13691 #undef fold
13697 /* When --enable-checking=fold, compute a digest of expr before
13698 and after actual fold call to see if fold did not accidentally
13699 change original expr. */
13701 tree
13703 {
13704 tree ret;
13707 htab_t ht;
13726 }
13728 void
13730 {
13733 htab_t ht;
13743 }
13745 static void
13747 {
13749 }
13751 static void
13753 {
13759 recursive_label:
13773 {
13774 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13778 }
13785 {
13786 /* Allow these fields to be modified. */
13787 tree tmp;
13795 {
13798 }
13799 }
13808 {
13811 {
13825 }
13829 {
13842 }
13859 {
13865 }
13870 {
13874 }
13885 {
13888 }
13898 }
13899 }
13901 /* Helper function for outputting the checksum of a tree T. When
13902 debugging with gdb, you can "define mynext" to be "next" followed
13903 by "call debug_fold_checksum (op0)", then just trace down till the
13904 outputs differ. */
13906 void
13908 {
13923 }
13925 #endif
13927 /* Fold a unary tree expression with code CODE of type TYPE with an
13928 operand OP0. Return a folded expression if successful. Otherwise,
13929 return a tree expression with code CODE of type TYPE with an
13930 operand OP0. */
13932 tree
13934 {
13935 tree tem;
13936 #ifdef ENABLE_FOLD_CHECKING
13939 htab_t ht;
13946 #endif
13952 #ifdef ENABLE_FOLD_CHECKING
13960 #endif
13962 }
13964 /* Fold a binary tree expression with code CODE of type TYPE with
13965 operands OP0 and OP1. Return a folded expression if successful.
13966 Otherwise, return a tree expression with code CODE of type TYPE
13967 with operands OP0 and OP1. */
13969 tree
13971 MEM_STAT_DECL)
13972 {
13973 tree tem;
13974 #ifdef ENABLE_FOLD_CHECKING
13980 htab_t ht;
13992 #endif
13998 #ifdef ENABLE_FOLD_CHECKING
14014 #endif
14016 }
14018 /* Fold a ternary tree expression with code CODE of type TYPE with
14019 operands OP0, OP1, and OP2. Return a folded expression if
14020 successful. Otherwise, return a tree expression with code CODE of
14021 type TYPE with operands OP0, OP1, and OP2. */
14023 tree
14025 MEM_STAT_DECL)
14026 {
14027 tree tem;
14028 #ifdef ENABLE_FOLD_CHECKING
14036 htab_t ht;
14053 #endif
14060 #ifdef ENABLE_FOLD_CHECKING
14084 #endif
14086 }
14088 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14089 arguments in ARGARRAY, and a null static chain.
14090 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14091 of type TYPE from the given operands as constructed by build_call_array. */
14093 tree
14095 {
14096 tree tem;
14097 #ifdef ENABLE_FOLD_CHECKING
14103 htab_t ht;
14117 #endif
14121 #ifdef ENABLE_FOLD_CHECKING
14138 #endif
14140 }
14142 /* Perform constant folding and related simplification of initializer
14143 expression EXPR. These behave identically to "fold_buildN" but ignore
14144 potential run-time traps and exceptions that fold must preserve. */
14146 #define START_FOLD_INIT \
14147 int saved_signaling_nans = flag_signaling_nans;\
14148 int saved_trapping_math = flag_trapping_math;\
14149 int saved_rounding_math = flag_rounding_math;\
14150 int saved_trapv = flag_trapv;\
14151 int saved_folding_initializer = folding_initializer;\
14152 flag_signaling_nans = 0;\
14153 flag_trapping_math = 0;\
14154 flag_rounding_math = 0;\
14155 flag_trapv = 0;\
14156 folding_initializer = 1;
14158 #define END_FOLD_INIT \
14159 flag_signaling_nans = saved_signaling_nans;\
14160 flag_trapping_math = saved_trapping_math;\
14161 flag_rounding_math = saved_rounding_math;\
14162 flag_trapv = saved_trapv;\
14163 folding_initializer = saved_folding_initializer;
14165 tree
14167 {
14168 tree result;
14169 START_FOLD_INIT;
14173 END_FOLD_INIT;
14175 }
14177 tree
14179 {
14180 tree result;
14181 START_FOLD_INIT;
14185 END_FOLD_INIT;
14187 }
14189 tree
14191 tree op2)
14192 {
14193 tree result;
14194 START_FOLD_INIT;
14198 END_FOLD_INIT;
14200 }
14202 tree
14205 {
14206 tree result;
14207 START_FOLD_INIT;
14211 END_FOLD_INIT;
14213 }
14215 #undef START_FOLD_INIT
14216 #undef END_FOLD_INIT
14218 /* Determine if first argument is a multiple of second argument. Return 0 if
14219 it is not, or we cannot easily determined it to be.
14221 An example of the sort of thing we care about (at this point; this routine
14222 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14223 fold cases do now) is discovering that
14225 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14227 is a multiple of
14229 SAVE_EXPR (J * 8)
14231 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14233 This code also handles discovering that
14235 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14237 is a multiple of 8 so we don't have to worry about dealing with a
14238 possible remainder.
14240 Note that we *look* inside a SAVE_EXPR only to determine how it was
14241 calculated; it is not safe for fold to do much of anything else with the
14242 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14243 at run time. For example, the latter example above *cannot* be implemented
14244 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14245 evaluation time of the original SAVE_EXPR is not necessarily the same at
14246 the time the new expression is evaluated. The only optimization of this
14247 sort that would be valid is changing
14249 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14251 divided by 8 to
14253 SAVE_EXPR (I) * SAVE_EXPR (J)
14255 (where the same SAVE_EXPR (J) is used in the original and the
14256 transformed version). */
14258 int
14260 {
14268 {
14270 /* Bitwise and provides a power of two multiple. If the mask is
14271 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14274 /* FALLTHRU */
14287 {
14291 /* const_binop may not detect overflow correctly,
14292 so check for it explicitly here. */
14298 size_one_node,
14302 }
14306 /* Can't handle conversions from non-integral or wider integral type. */
14312 /* .. fall through ... */
14329 }
14330 }
14332 /* Return true if CODE or TYPE is known to be non-negative. */
14334 static bool
14336 {
14339 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14340 have a signed:1 type (where the value is -1 and 0). */
14343 }
14345 /* Return true if (CODE OP0) is known to be non-negative. If the return
14346 value is based on the assumption that signed overflow is undefined,
14347 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14348 *STRICT_OVERFLOW_P. */
14350 bool
14353 {
14358 {
14360 /* We can't return 1 if flag_wrapv is set because
14361 ABS_EXPR<INT_MIN> = INT_MIN. */
14365 {
14368 }
14375 strict_overflow_p);
14378 {
14383 {
14386 strict_overflow_p);
14388 {
14392 strict_overflow_p);
14393 }
14394 }
14396 {
14399 strict_overflow_p);
14403 }
14404 }
14409 }
14411 /* We don't know sign of `t', so be conservative and return false. */
14413 }
14415 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14416 value is based on the assumption that signed overflow is undefined,
14417 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14418 *STRICT_OVERFLOW_P. */
14420 bool
14423 {
14428 {
14433 strict_overflow_p)
14435 strict_overflow_p));
14437 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14438 both unsigned and at least 2 bits shorter than the result. */
14442 {
14447 {
14451 }
14452 }
14457 {
14458 /* x * x for floating point x is always non-negative. */
14462 strict_overflow_p)
14464 strict_overflow_p));
14465 }
14467 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14468 both unsigned and their total bits is shorter than the result. */
14472 {
14491 {
14501 }
14502 }
14508 strict_overflow_p)
14510 strict_overflow_p));
14521 strict_overflow_p)
14523 strict_overflow_p));
14530 strict_overflow_p);
14533 }
14535 /* We don't know sign of `t', so be conservative and return false. */
14537 }
14539 /* Return true if T is known to be non-negative. If the return
14540 value is based on the assumption that signed overflow is undefined,
14541 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14542 *STRICT_OVERFLOW_P. */
14544 bool
14546 {
14551 {
14563 strict_overflow_p)
14565 strict_overflow_p));
14569 }
14570 /* We don't know sign of `t', so be conservative and return false. */
14572 }
14574 /* Return true if T is known to be non-negative. If the return
14575 value is based on the assumption that signed overflow is undefined,
14576 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14577 *STRICT_OVERFLOW_P. */
14579 bool
14582 {
14585 {
14603 /* Always true. */
14607 /* sqrt(-0.0) is -0.0. */
14611 strict_overflow_p);
14644 /* True if the 1st argument is nonnegative. */
14646 strict_overflow_p);
14649 /* True if the 1st OR 2nd arguments are nonnegative. */
14651 strict_overflow_p)
14653 strict_overflow_p)));
14656 /* True if the 1st AND 2nd arguments are nonnegative. */
14658 strict_overflow_p)
14660 strict_overflow_p)));
14663 /* True if the 2nd argument is nonnegative. */
14665 strict_overflow_p);
14668 /* True if the 1st argument is nonnegative or the second
14669 argument is an even integer. */
14674 strict_overflow_p);
14677 /* True if the 1st argument is nonnegative or the second
14678 argument is an even integer valued real. */
14680 {
14681 REAL_VALUE_TYPE c;
14682 HOST_WIDE_INT n;
14687 {
14688 REAL_VALUE_TYPE cint;
14693 }
14694 }
14696 strict_overflow_p);
14700 }
14702 type);
14703 }
14705 /* Return true if T is known to be non-negative. If the return
14706 value is based on the assumption that signed overflow is undefined,
14707 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14708 *STRICT_OVERFLOW_P. */
14710 bool
14712 {
14718 {
14720 {
14724 /* If the initializer is non-void, then it's a normal expression
14725 that will be assigned to the slot. */
14729 /* Otherwise, the initializer sets the slot in some way. One common
14730 way is an assignment statement at the end of the initializer. */
14732 {
14740 else
14742 }
14746 strict_overflow_p);
14749 }
14752 {
14758 arg0,
14759 arg1,
14760 strict_overflow_p);
14761 }
14765 strict_overflow_p);
14768 strict_overflow_p);
14771 strict_overflow_p);
14776 }
14778 /* We don't know sign of `t', so be conservative and return false. */
14780 }
14782 /* Return true if T is known to be non-negative. If the return
14783 value is based on the assumption that signed overflow is undefined,
14784 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14785 *STRICT_OVERFLOW_P. */
14787 bool
14789 {
14796 {
14803 strict_overflow_p);
14809 strict_overflow_p);
14818 }
14821 {
14829 strict_overflow_p);
14834 strict_overflow_p);
14849 }
14850 }
14852 /* Return true if `t' is known to be non-negative. Handle warnings
14853 about undefined signed overflow. */
14855 bool
14857 {
14864 "determining that expression is always "
14866 WARN_STRICT_OVERFLOW_MISC);
14868 }
14871 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14872 For floating point we further ensure that T is not denormal.
14873 Similar logic is present in nonzero_address in rtlanal.h.
14875 If the return value is based on the assumption that signed overflow
14876 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14877 change *STRICT_OVERFLOW_P. */
14879 bool
14882 {
14884 {
14887 strict_overflow_p);
14890 {
14896 strict_overflow_p));
14897 }
14902 strict_overflow_p);
14906 }
14909 }
14911 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14912 For floating point we further ensure that T is not denormal.
14913 Similar logic is present in nonzero_address in rtlanal.h.
14915 If the return value is based on the assumption that signed overflow
14916 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14917 change *STRICT_OVERFLOW_P. */
14919 bool
14921 tree type,
14922 tree op0,
14924 {
14927 {
14931 {
14932 /* With the presence of negative values it is hard
14933 to say something. */
14940 /* One of operands must be positive and the other non-negative. */
14941 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14942 overflows, on a twos-complement machine the sum of two
14943 nonnegative numbers can never be zero. */
14945 strict_overflow_p)
14947 strict_overflow_p));
14948 }
14953 {
14955 strict_overflow_p)
14957 strict_overflow_p))
14958 {
14961 }
14962 }
14971 {
14974 }
14981 {
14985 /* When both operands are nonzero, then MAX must be too. */
14987 strict_overflow_p))
14990 /* MAX where operand 0 is positive is positive. */
14992 strict_overflow_p);
14993 }
14994 /* MAX where operand 1 is positive is positive. */
14999 {
15003 }
15008 strict_overflow_p)
15010 strict_overflow_p));
15014 }
15017 }
15019 /* Return true when T is an address and is known to be nonzero.
15020 For floating point we further ensure that T is not denormal.
15021 Similar logic is present in nonzero_address in rtlanal.h.
15023 If the return value is based on the assumption that signed overflow
15024 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15025 change *STRICT_OVERFLOW_P. */
15027 bool
15029 {
15032 {
15037 {
15043 /* Weak declarations may link to NULL. Other things may also be NULL
15044 so protect with -fdelete-null-pointer-checks; but not variables
15045 allocated on the stack. */
15047 && (flag_delete_null_pointer_checks
15051 /* Constants are never weak. */
15056 }
15064 {
15068 }
15073 }
15075 }
15077 /* Return true when T is an address and is known to be nonzero.
15078 For floating point we further ensure that T is not denormal.
15079 Similar logic is present in nonzero_address in rtlanal.h.
15081 If the return value is based on the assumption that signed overflow
15082 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15083 change *STRICT_OVERFLOW_P. */
15085 bool
15087 {
15091 /* Doing something useful for floating point would need more work. */
15097 {
15100 strict_overflow_p);
15106 strict_overflow_p);
15114 }
15117 {
15120 strict_overflow_p);
15128 strict_overflow_p);
15145 strict_overflow_p);
15149 strict_overflow_p);
15156 }
15158 }
15160 /* Return true when T is an address and is known to be nonzero.
15161 Handle warnings about undefined signed overflow. */
15163 bool
15165 {
15172 "determining that expression is always "
15174 WARN_STRICT_OVERFLOW_MISC);
15176 }
15178 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15179 attempt to fold the expression to a constant without modifying TYPE,
15180 OP0 or OP1.
15182 If the expression could be simplified to a constant, then return
15183 the constant. If the expression would not be simplified to a
15184 constant, then return NULL_TREE. */
15186 tree
15188 {
15191 }
15193 /* Given the components of a unary expression CODE, TYPE and OP0,
15194 attempt to fold the expression to a constant without modifying
15195 TYPE or OP0.
15197 If the expression could be simplified to a constant, then return
15198 the constant. If the expression would not be simplified to a
15199 constant, then return NULL_TREE. */
15201 tree
15203 {
15206 }
15208 /* If EXP represents referencing an element in a constant string
15209 (either via pointer arithmetic or array indexing), return the
15210 tree representing the value accessed, otherwise return NULL. */
15212 tree
15214 {
15218 {
15220 tree index;
15221 tree string;
15225 else
15226 {
15230 /* Optimize the special-case of a zero lower bound.
15232 We convert the low_bound to sizetype to avoid some problems
15233 with constant folding. (E.g. suppose the lower bound is 1,
15234 and its mode is QI. Without the conversion,l (ARRAY
15235 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15236 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15241 }
15254 }
15256 }
15258 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15259 an integer constant, real, or fixed-point constant.
15261 TYPE is the type of the result. */
15263 static tree
15265 {
15269 {
15271 {
15273 HOST_WIDE_INT high;
15281 }
15288 {
15289 FIXED_VALUE_TYPE f;
15294 /* Propagate overflow flags. */
15298 }
15302 }
15305 }
15307 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15308 an integer constant or real constant.
15310 TYPE is the type of the result. */
15312 tree
15314 {
15318 {
15320 /* If the value is unsigned, then the absolute value is
15321 the same as the ordinary value. */
15324 /* Similarly, if the value is non-negative. */
15327 /* If the value is negative, then the absolute value is
15328 its negation. */
15329 else
15330 {
15332 HOST_WIDE_INT high;
15338 }
15344 else
15350 }
15353 }
15355 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15356 constant. TYPE is the type of the result. */
15358 static tree
15360 {
15370 }
15372 /* Given CODE, a relational operator, the target type, TYPE and two
15373 constant operands OP0 and OP1, return the result of the
15374 relational operation. If the result is not a compile time
15375 constant, then return NULL_TREE. */
15377 static tree
15379 {
15382 /* From here on, the only cases we handle are when the result is
15383 known to be a constant. */
15386 {
15390 /* Handle the cases where either operand is a NaN. */
15392 {
15394 {
15422 }
15425 }
15428 }
15431 {
15435 }
15437 /* Handle equality/inequality of complex constants. */
15439 {
15450 else
15452 }
15454 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15456 To compute GT, swap the arguments and do LT.
15457 To compute GE, do LT and invert the result.
15458 To compute LE, swap the arguments, do LT and invert the result.
15459 To compute NE, do EQ and invert the result.
15461 Therefore, the code below must handle only EQ and LT. */
15464 {
15469 }
15471 /* Note that it is safe to invert for real values here because we
15472 have already handled the one case that it matters. */
15476 {
15479 }
15481 /* Compute a result for LT or EQ if args permit;
15482 Otherwise return T. */
15484 {
15489 else
15491 }
15492 else
15498 }
15500 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15501 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15502 itself. */
15504 tree
15506 {
15507 /* If the expression does not have side effects then we don't have to wrap
15508 it with a cleanup point expression. */
15512 /* If the expression is a return, check to see if the expression inside the
15513 return has no side effects or the right hand side of the modify expression
15514 inside the return. If either don't have side effects set we don't need to
15515 wrap the expression in a cleanup point expression. Note we don't check the
15516 left hand side of the modify because it should always be a return decl. */
15518 {
15525 }
15528 }
15530 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15531 of an indirection through OP0, or NULL_TREE if no simplification is
15532 possible. */
15534 tree
15536 {
15538 tree subtype;
15546 {
15549 /* *&CONST_DECL -> to the value of the const decl. */
15552 /* *&p => p; make sure to handle *&"str"[cst] here. */
15554 {
15558 else
15560 }
15561 /* *(foo *)&fooarray => fooarray[0] */
15564 {
15570 }
15571 /* *(foo *)&complexfoo => __real__ complexfoo */
15575 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15578 {
15582 }
15583 }
15585 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15588 {
15591 tree op00type;
15598 {
15609 }
15610 }
15613 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15616 {
15619 tree op00type;
15626 {
15630 }
15631 }
15633 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15636 {
15637 tree type_domain;
15644 }
15647 }
15649 /* Builds an expression for an indirection through T, simplifying some
15650 cases. */
15652 tree
15654 {
15660 else
15662 }
15664 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15666 tree
15668 {
15673 else
15675 }
15677 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15678 whose result is ignored. The type of the returned tree need not be
15679 the same as the original expression. */
15681 tree
15683 {
15689 {
15700 else
15706 {
15722 }
15727 }
15728 }
15730 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15731 This can only be applied to objects of a sizetype. */
15733 tree
15735 {
15742 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15743 have to do anything. Only do this when we are not given a const,
15744 because in that case, this check is more expensive than just
15745 doing it. */
15747 {
15752 }
15754 /* If divisor is a power of two, simplify this to bit manipulation. */
15756 {
15758 {
15771 {
15772 high++;
15775 }
15779 }
15780 else
15781 {
15782 tree t;
15788 }
15789 }
15790 else
15791 {
15796 }
15799 }
15801 /* Likewise, but round down. */
15803 tree
15805 {
15812 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15813 have to do anything. Only do this when we are not given a const,
15814 because in that case, this check is more expensive than just
15815 doing it. */
15817 {
15822 }
15824 /* If divisor is a power of two, simplify this to bit manipulation. */
15826 {
15827 tree t;
15831 }
15832 else
15833 {
15838 }
15841 }
15843 /* Returns the pointer to the base of the object addressed by EXP and
15844 extracts the information about the offset of the access, storing it
15845 to PBITPOS and POFFSET. */
15847 static tree
15850 {
15851 tree core;
15854 HOST_WIDE_INT bitsize;
15857 {
15862 }
15863 else
15864 {
15868 }
15871 }
15873 /* Returns true if addresses of E1 and E2 differ by a constant, false
15874 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15876 bool
15878 {
15892 {
15902 }
15904 {
15905 /* If only one of the offsets is non-constant, the difference cannot
15906 be a constant. */
15908 }
15909 else
15914 }
15916 /* Simplify the floating point expression EXP when the sign of the
15917 result is not significant. Return NULL_TREE if no simplification
15918 is possible. */
15920 tree
15922 {
15926 {
15961 {
15964 {
15966 /* Strip copysign function call, return the 1st argument. */
15972 /* Strip sign ops from the argument of "odd" math functions. */
15974 {
15978 }
15980 }
15981 }
15986 }
15988 }