| blob | 14b9f100b517281536c8e82bf54b209dd9cc3182 |
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
3004 {
3009 }
3010 }
3011 \f
3012 /* Return nonzero if two operands (typically of the same tree node)
3013 are necessarily equal. If either argument has side-effects this
3014 function returns zero. FLAGS modifies behavior as follows:
3016 If OEP_ONLY_CONST is set, only return nonzero for constants.
3017 This function tests whether the operands are indistinguishable;
3018 it does not test whether they are equal using C's == operation.
3019 The distinction is important for IEEE floating point, because
3020 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3021 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3023 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3024 even though it may hold multiple values during a function.
3025 This is because a GCC tree node guarantees that nothing else is
3026 executed between the evaluation of its "operands" (which may often
3027 be evaluated in arbitrary order). Hence if the operands themselves
3028 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3029 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3030 unset means assuming isochronic (or instantaneous) tree equivalence.
3031 Unless comparing arbitrary expression trees, such as from different
3032 statements, this flag can usually be left unset.
3034 If OEP_PURE_SAME is set, then pure functions with identical arguments
3035 are considered the same. It is used when the caller has other ways
3036 to ensure that global memory is unchanged in between. */
3038 int
3040 {
3041 /* If either is ERROR_MARK, they aren't equal. */
3045 /* Check equality of integer constants before bailing out due to
3046 precision differences. */
3050 /* If both types don't have the same signedness, then we can't consider
3051 them equal. We must check this before the STRIP_NOPS calls
3052 because they may change the signedness of the arguments. As pointers
3053 strictly don't have a signedness, require either two pointers or
3054 two non-pointers as well. */
3059 /* If both types don't have the same precision, then it is not safe
3060 to strip NOPs. */
3067 /* In case both args are comparisons but with different comparison
3068 code, try to swap the comparison operands of one arg to produce
3069 a match and compare that variant. */
3073 {
3081 }
3084 /* This is needed for conversions and for COMPONENT_REF.
3085 Might as well play it safe and always test this. */
3091 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3092 We don't care about side effects in that case because the SAVE_EXPR
3093 takes care of that for us. In all other cases, two expressions are
3094 equal if they have no side effects. If we have two identical
3095 expressions with side effects that should be treated the same due
3096 to the only side effects being identical SAVE_EXPR's, that will
3097 be detected in the recursive calls below. */
3103 /* Next handle constant cases, those for which we can return 1 even
3104 if ONLY_CONST is set. */
3107 {
3122 {
3123 /* If we do not distinguish between signed and unsigned zero,
3124 consider them equal. */
3127 }
3131 {
3137 {
3139 flags))
3143 }
3146 }
3150 flags)
3152 flags));
3165 }
3170 /* Define macros to test an operand from arg0 and arg1 for equality and a
3171 variant that allows null and views null as being different from any
3172 non-null value. In the latter case, if either is null, the both
3173 must be; otherwise, do the normal comparison. */
3174 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3175 TREE_OPERAND (arg1, N), flags)
3177 #define OP_SAME_WITH_NULL(N) \
3178 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3179 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3182 {
3184 /* Two conversions are equal only if signedness and modes match. */
3186 {
3187 CASE_CONVERT:
3195 }
3205 /* For commutative ops, allow the other order. */
3213 /* If either of the pointer (or reference) expressions we are
3214 dereferencing contain a side effect, these cannot be equal. */
3220 {
3230 /* Operands 2 and 3 may be null.
3231 Compare the array index by value if it is constant first as we
3232 may have different types but same value here. */
3241 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3242 may be NULL when we're called to compare MEM_EXPRs. */
3252 }
3256 {
3271 /* Otherwise take into account this is a commutative operation. */
3282 }
3286 {
3288 /* If the CALL_EXPRs call different functions, then they
3289 clearly can not be equal. */
3291 flags))
3294 {
3298 else
3302 }
3304 /* Now see if all the arguments are the same. */
3305 {
3316 /* If we get here and both argument lists are exhausted
3317 then the CALL_EXPRs are equal. */
3319 }
3322 }
3325 /* Consider __builtin_sqrt equal to sqrt. */
3333 }
3335 #undef OP_SAME
3336 #undef OP_SAME_WITH_NULL
3337 }
3338 \f
3339 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3340 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3342 When in doubt, return 0. */
3344 static int
3346 {
3358 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3359 and see if the inner values are the same. This removes any
3360 signedness comparison, which doesn't matter here. */
3367 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3368 actual comparison operand, ARG0.
3370 First throw away any conversions to wider types
3371 already present in the operands. */
3380 {
3383 /* Make sure shorter operand is extended the right way
3384 to match the longer operand. */
3390 }
3393 }
3394 \f
3395 /* See if ARG is an expression that is either a comparison or is performing
3396 arithmetic on comparisons. The comparisons must only be comparing
3397 two different values, which will be stored in *CVAL1 and *CVAL2; if
3398 they are nonzero it means that some operands have already been found.
3399 No variables may be used anywhere else in the expression except in the
3400 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3401 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3403 If this is true, return 1. Otherwise, return zero. */
3405 static int
3407 {
3411 /* We can handle some of the tcc_expression cases here. */
3421 {
3422 /* If we've already found a CVAL1 or CVAL2, this expression is
3423 two complex to handle. */
3429 }
3432 {
3455 /* First see if we can handle the first operand, then the second. For
3456 the second operand, we know *CVAL1 can't be zero. It must be that
3457 one side of the comparison is each of the values; test for the
3458 case where this isn't true by failing if the two operands
3459 are the same. */
3468 ;
3472 ;
3473 else
3477 ;
3481 ;
3482 else
3489 }
3490 }
3491 \f
3492 /* ARG is a tree that is known to contain just arithmetic operations and
3493 comparisons. Evaluate the operations in the tree substituting NEW0 for
3494 any occurrence of OLD0 as an operand of a comparison and likewise for
3495 NEW1 and OLD1. */
3497 static tree
3499 {
3504 /* We can handle some of the tcc_expression cases here. */
3512 {
3527 {
3544 }
3545 /* Fall through - ??? */
3548 {
3552 /* We need to check both for exact equality and tree equality. The
3553 former will be true if the operand has a side-effect. In that
3554 case, we know the operand occurred exactly once. */
3567 }
3571 }
3572 }
3573 \f
3574 /* Return a tree for the case when the result of an expression is RESULT
3575 converted to TYPE and OMITTED was previously an operand of the expression
3576 but is now not needed (e.g., we folded OMITTED * 0).
3578 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3579 the conversion of RESULT to TYPE. */
3581 tree
3583 {
3586 /* If the resulting operand is an empty statement, just return the omitted
3587 statement casted to void. */
3595 }
3597 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3599 static tree
3601 {
3604 /* If the resulting operand is an empty statement, just return the omitted
3605 statement casted to void. */
3613 }
3615 /* Return a tree for the case when the result of an expression is RESULT
3616 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3617 of the expression but are now not needed.
3619 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3620 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3621 evaluated before OMITTED2. Otherwise, if neither has side effects,
3622 just do the conversion of RESULT to TYPE. */
3624 tree
3626 {
3635 }
3637 \f
3638 /* Return a simplified tree node for the truth-negation of ARG. This
3639 never alters ARG itself. We assume that ARG is an operation that
3640 returns a truth value (0 or 1).
3642 FIXME: one would think we would fold the result, but it causes
3643 problems with the dominator optimizer. */
3645 tree
3647 {
3651 /* If this is a comparison, we can simply invert it, except for
3652 floating-point non-equality comparisons, in which case we just
3653 enclose a TRUTH_NOT_EXPR around what we have. */
3656 {
3659 && flag_trapping_math
3672 }
3675 {
3692 /* Here we can invert either operand. We invert the first operand
3693 unless the second operand is a TRUTH_NOT_EXPR in which case our
3694 result is the XOR of the first operand with the inside of the
3695 negation of the second operand. */
3700 else
3722 {
3725 /* A COND_EXPR may have a throw as one operand, which
3726 then has void type. Just leave void operands
3727 as they are. */
3734 }
3746 {
3749 }
3751 /* ... fall through ... */
3777 }
3783 }
3785 /* Return a simplified tree node for the truth-negation of ARG. This
3786 never alters ARG itself. We assume that ARG is an operation that
3787 returns a truth value (0 or 1).
3789 FIXME: one would think we would fold the result, but it causes
3790 problems with the dominator optimizer. */
3792 tree
3794 {
3795 tree tem;
3805 }
3807 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3808 operands are another bit-wise operation with a common input. If so,
3809 distribute the bit operations to save an operation and possibly two if
3810 constants are involved. For example, convert
3811 (A | B) & (A | C) into A | (B & C)
3812 Further simplification will occur if B and C are constants.
3814 If this optimization cannot be done, 0 will be returned. */
3816 static tree
3818 {
3819 tree common;
3829 {
3833 }
3835 {
3839 }
3841 {
3845 }
3847 {
3851 }
3852 else
3860 }
3862 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3863 with code CODE. This optimization is unsafe. */
3864 static tree
3866 {
3870 /* (A / C) +- (B / C) -> (A +- B) / C. */
3880 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3885 {
3897 }
3900 }
3901 \f
3902 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3903 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3905 static tree
3908 {
3912 {
3919 }
3933 }
3935 /* Optimize a bit-field compare.
3937 There are two cases: First is a compare against a constant and the
3938 second is a comparison of two items where the fields are at the same
3939 bit position relative to the start of a chunk (byte, halfword, word)
3940 large enough to contain it. In these cases we can avoid the shift
3941 implicit in bitfield extractions.
3943 For constants, we emit a compare of the shifted constant with the
3944 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3945 compared. For two fields at the same position, we do the ANDs with the
3946 similar mask and compare the result of the ANDs.
3948 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3949 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3950 are the left and right operands of the comparison, respectively.
3952 If the optimization described above can be done, we return the resulting
3953 tree. Otherwise we return zero. */
3955 static tree
3958 {
3967 tree mask;
3968 tree offset;
3970 /* Get all the information about the extractions being done. If the bit size
3971 if the same as the size of the underlying object, we aren't doing an
3972 extraction at all and so can do nothing. We also don't want to
3973 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3974 then will no longer be able to replace it. */
3982 {
3983 /* If this is not a constant, we can only do something if bit positions,
3984 sizes, and signedness are the same. */
3992 }
3994 /* See if we can find a mode to refer to this field. We should be able to,
3995 but fail if we can't. */
4004 /* Set signed and unsigned types of the precision of this mode for the
4005 shifts below. */
4009 /* Compute the bit position and size for the new reference and our offset
4010 within it. If the new reference is the same size as the original, we
4011 won't optimize anything, so return zero. */
4021 /* Make the mask to be used against the extracted field. */
4028 /* If not comparing with constant, just rework the comparison
4029 and return. */
4033 unsigned_type,
4036 mask),
4039 unsigned_type,
4042 mask));
4044 /* Otherwise, we are handling the constant case. See if the constant is too
4045 big for the field. Warn and return a tree of for 0 (false) if so. We do
4046 this not only for its own sake, but to avoid having to test for this
4047 error case below. If we didn't, we might generate wrong code.
4049 For unsigned fields, the constant shifted right by the field length should
4050 be all zero. For signed fields, the high-order bits should agree with
4051 the sign bit. */
4054 {
4058 {
4062 }
4063 }
4064 else
4065 {
4069 {
4073 }
4074 }
4076 /* Single-bit compares should always be against zero. */
4078 {
4081 }
4083 /* Make a new bitfield reference, shift the constant over the
4084 appropriate number of bits and mask it with the computed mask
4085 (in case this was a signed field). If we changed it, make a new one. */
4088 {
4091 }
4101 rhs);
4102 }
4103 \f
4104 /* Subroutine for fold_truthop: decode a field reference.
4106 If EXP is a comparison reference, we return the innermost reference.
4108 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4109 set to the starting bit number.
4111 If the innermost field can be completely contained in a mode-sized
4112 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4114 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4115 otherwise it is not changed.
4117 *PUNSIGNEDP is set to the signedness of the field.
4119 *PMASK is set to the mask used. This is either contained in a
4120 BIT_AND_EXPR or derived from the width of the field.
4122 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4124 Return 0 if this is not a component reference or is one that we can't
4125 do anything with. */
4127 static tree
4132 {
4136 tree unsigned_type;
4139 /* All the optimizations using this function assume integer fields.
4140 There are problems with FP fields since the type_for_size call
4141 below can fail for, e.g., XFmode. */
4145 /* We are interested in the bare arrangement of bits, so strip everything
4146 that doesn't affect the machine mode. However, record the type of the
4147 outermost expression if it may matter below. */
4154 {
4160 }
4169 /* If the number of bits in the reference is the same as the bitsize of
4170 the outer type, then the outer type gives the signedness. Otherwise
4171 (in case of a small bitfield) the signedness is unchanged. */
4175 /* Compute the mask to access the bitfield. */
4184 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4192 }
4194 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4195 bit positions. */
4197 static int
4199 {
4202 tree tmask;
4206 return
4213 }
4215 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4216 represents the sign bit of EXP's type. If EXP represents a sign
4217 or zero extension, also test VAL against the unextended type.
4218 The return value is the (sub)expression whose sign bit is VAL,
4219 or NULL_TREE otherwise. */
4221 static tree
4223 {
4227 tree t;
4229 /* Tree EXP must have an integral type. */
4234 /* Tree VAL must be an integer constant. */
4241 {
4248 }
4249 else
4250 {
4257 }
4259 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4260 treat VAL as if it were unsigned. */
4265 /* Handle extension from a narrower type. */
4271 }
4273 /* Subroutine for fold_truthop: determine if an operand is simple enough
4274 to be evaluated unconditionally. */
4276 static int
4278 {
4279 /* Strip any conversions that don't change the machine mode. */
4288 /* Don't regard global variables as simple. They may be
4289 allocated in ways unknown to the compiler (shared memory,
4290 #pragma weak, etc). */
4293 /* Loading a static variable is unduly expensive, but global
4294 registers aren't expensive. */
4296 }
4297 \f
4298 /* The following functions are subroutines to fold_range_test and allow it to
4299 try to change a logical combination of comparisons into a range test.
4301 For example, both
4302 X == 2 || X == 3 || X == 4 || X == 5
4303 and
4304 X >= 2 && X <= 5
4305 are converted to
4306 (unsigned) (X - 2) <= 3
4308 We describe each set of comparisons as being either inside or outside
4309 a range, using a variable named like IN_P, and then describe the
4310 range with a lower and upper bound. If one of the bounds is omitted,
4311 it represents either the highest or lowest value of the type.
4313 In the comments below, we represent a range by two numbers in brackets
4314 preceded by a "+" to designate being inside that range, or a "-" to
4315 designate being outside that range, so the condition can be inverted by
4316 flipping the prefix. An omitted bound is represented by a "-". For
4317 example, "- [-, 10]" means being outside the range starting at the lowest
4318 possible value and ending at 10, in other words, being greater than 10.
4319 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4320 always false.
4322 We set up things so that the missing bounds are handled in a consistent
4323 manner so neither a missing bound nor "true" and "false" need to be
4324 handled using a special case. */
4326 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4327 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4328 and UPPER1_P are nonzero if the respective argument is an upper bound
4329 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4330 must be specified for a comparison. ARG1 will be converted to ARG0's
4331 type if both are specified. */
4333 static tree
4336 {
4337 tree tem;
4341 /* If neither arg represents infinity, do the normal operation.
4342 Else, if not a comparison, return infinity. Else handle the special
4343 comparison rules. Note that most of the cases below won't occur, but
4344 are handled for consistency. */
4347 {
4352 }
4357 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4358 for neither. In real maths, we cannot assume open ended ranges are
4359 the same. But, this is computer arithmetic, where numbers are finite.
4360 We can therefore make the transformation of any unbounded range with
4361 the value Z, Z being greater than any representable number. This permits
4362 us to treat unbounded ranges as equal. */
4366 {
4387 }
4390 }
4391 \f
4392 /* Given EXP, a logical expression, set the range it is testing into
4393 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4394 actually being tested. *PLOW and *PHIGH will be made of the same
4395 type as the returned expression. If EXP is not a comparison, we
4396 will most likely not be returning a useful value and range. Set
4397 *STRICT_OVERFLOW_P to true if the return value is only valid
4398 because signed overflow is undefined; otherwise, do not change
4399 *STRICT_OVERFLOW_P. */
4401 static tree
4404 {
4411 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4412 and see if we can refine the range. Some of the cases below may not
4413 happen, but it doesn't seem worth worrying about this. We "continue"
4414 the outer loop when we've changed something; otherwise we "break"
4415 the switch, which will "break" the while. */
4421 {
4426 {
4438 }
4441 {
4448 /* We can only do something if the range is testing for zero
4449 and if the second operand is an integer constant. Note that
4450 saying something is "in" the range we make is done by
4451 complementing IN_P since it will set in the initial case of
4452 being not equal to zero; "out" is leaving it alone. */
4459 {
4480 }
4482 /* If this is an unsigned comparison, we also know that EXP is
4483 greater than or equal to zero. We base the range tests we make
4484 on that fact, so we record it here so we can parse existing
4485 range tests. We test arg0_type since often the return type
4486 of, e.g. EQ_EXPR, is boolean. */
4488 {
4492 NULL_TREE))
4497 /* If the high bound is missing, but we have a nonzero low
4498 bound, reverse the range so it goes from zero to the low bound
4499 minus 1. */
4501 {
4506 }
4507 }
4513 /* (-x) IN [a,b] -> x in [-b, -a] */
4525 /* ~ X -> -X - 1 */
4534 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4535 move a constant to the other side. */
4540 /* If EXP is signed, any overflow in the computation is undefined,
4541 so we don't worry about it so long as our computations on
4542 the bounds don't overflow. For unsigned, overflow is defined
4543 and this is exactly the right thing. */
4555 /* Check for an unsigned range which has wrapped around the maximum
4556 value thus making n_high < n_low, and normalize it. */
4558 {
4564 /* If the range is of the form +/- [ x+1, x ], we won't
4565 be able to normalize it. But then, it represents the
4566 whole range or the empty set, so make it
4567 +/- [ -, - ]. */
4571 else
4573 }
4574 else
4598 /* If we're converting arg0 from an unsigned type, to exp,
4599 a signed type, we will be doing the comparison as unsigned.
4600 The tests above have already verified that LOW and HIGH
4601 are both positive.
4603 So we have to ensure that we will handle large unsigned
4604 values the same way that the current signed bounds treat
4605 negative values. */
4608 {
4609 tree high_positive;
4610 tree equiv_type;
4611 /* For fixed-point modes, we need to pass the saturating flag
4612 as the 2nd parameter. */
4617 else
4621 /* A range without an upper bound is, naturally, unbounded.
4622 Since convert would have cropped a very large value, use
4623 the max value for the destination type. */
4624 high_positive
4631 high_positive),
4634 /* If the low bound is specified, "and" the range with the
4635 range for which the original unsigned value will be
4636 positive. */
4638 {
4642 integer_zero_node),
4643 high_positive))
4647 }
4648 else
4649 {
4650 /* Otherwise, "or" the range with the range of the input
4651 that will be interpreted as negative. */
4655 integer_zero_node),
4656 high_positive))
4660 }
4661 }
4669 }
4672 }
4674 /* If EXP is a constant, we can evaluate whether this is true or false. */
4676 {
4683 }
4687 }
4688 \f
4689 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4690 type, TYPE, return an expression to test if EXP is in (or out of, depending
4691 on IN_P) the range. Return 0 if the test couldn't be created. */
4693 static tree
4695 {
4699 #ifdef HAVE_canonicalize_funcptr_for_compare
4700 /* Disable this optimization for function pointer expressions
4701 on targets that require function pointer canonicalization. */
4706 #endif
4709 {
4715 }
4733 {
4735 {
4739 }
4741 }
4743 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4745 {
4747 HOST_WIDE_INT hi;
4752 {
4755 }
4756 else
4757 {
4760 }
4763 {
4765 {
4768 etype
4770 else
4773 }
4776 }
4777 }
4779 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4780 This requires wrap-around arithmetics for the type of the expression. */
4783 {
4787 /* There is no requirement that LOW be within the range of ETYPE
4788 if the latter is a subtype. It must, however, be within the base
4789 type of ETYPE. So be sure we do the subtraction in that type. */
4791 {
4793 /* But not in an enumeral or boolean type though. */
4795 }
4804 }
4806 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4809 {
4812 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4813 for the type in question, as we rely on this here. */
4823 else
4825 }
4835 {
4837 {
4843 }
4845 }
4853 }
4854 \f
4855 /* Return the predecessor of VAL in its type, handling the infinite case. */
4857 static tree
4859 {
4865 else
4867 }
4869 /* Return the successor of VAL in its type, handling the infinite case. */
4871 static tree
4873 {
4879 else
4881 }
4883 /* Given two ranges, see if we can merge them into one. Return 1 if we
4884 can, 0 if we can't. Set the output range into the specified parameters. */
4886 static int
4889 {
4893 tree tem;
4903 /* Make range 0 be the range that starts first, or ends last if they
4904 start at the same value. Swap them if it isn't. */
4907 || (lowequal
4910 {
4914 }
4916 /* Now flag two cases, whether the ranges are disjoint or whether the
4917 second range is totally subsumed in the first. Note that the tests
4918 below are simplified by the ones above. */
4924 /* We now have four cases, depending on whether we are including or
4925 excluding the two ranges. */
4927 {
4928 /* If they don't overlap, the result is false. If the second range
4929 is a subset it is the result. Otherwise, the range is from the start
4930 of the second to the end of the first. */
4935 else
4937 }
4940 {
4941 /* If they don't overlap, the result is the first range. If they are
4942 equal, the result is false. If the second range is a subset of the
4943 first, and the ranges begin at the same place, we go from just after
4944 the end of the second range to the end of the first. If the second
4945 range is not a subset of the first, or if it is a subset and both
4946 ranges end at the same place, the range starts at the start of the
4947 first range and ends just before the second range.
4948 Otherwise, we can't describe this as a single range. */
4954 {
4959 {
4960 /* We are in the weird situation where high0 > high1 but
4961 high1 has no successor. Punt. */
4963 }
4964 }
4966 {
4971 {
4972 /* low0 < low1 but low1 has no predecessor. Punt. */
4974 }
4975 }
4976 else
4978 }
4981 {
4982 /* If they don't overlap, the result is the second range. If the second
4983 is a subset of the first, the result is false. Otherwise,
4984 the range starts just after the first range and ends at the
4985 end of the second. */
4990 else
4991 {
4996 {
4997 /* high1 > high0 but high0 has no successor. Punt. */
4999 }
5000 }
5001 }
5003 else
5004 {
5005 /* The case where we are excluding both ranges. Here the complex case
5006 is if they don't overlap. In that case, the only time we have a
5007 range is if they are adjacent. If the second is a subset of the
5008 first, the result is the first. Otherwise, the range to exclude
5009 starts at the beginning of the first range and ends at the end of the
5010 second. */
5012 {
5017 else
5018 {
5019 /* Canonicalize - [min, x] into - [-, x]. */
5022 {
5027 /* FALLTHROUGH */
5040 }
5042 /* Canonicalize - [x, max] into - [x, -]. */
5045 {
5050 /* FALLTHROUGH */
5065 }
5067 /* The ranges might be also adjacent between the maximum and
5068 minimum values of the given type. For
5069 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5070 return + [x + 1, y - 1]. */
5072 {
5079 }
5080 else
5082 }
5083 }
5086 else
5088 }
5092 }
5093 \f
5095 /* Subroutine of fold, looking inside expressions of the form
5096 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5097 of the COND_EXPR. This function is being used also to optimize
5098 A op B ? C : A, by reversing the comparison first.
5100 Return a folded expression whose code is not a COND_EXPR
5101 anymore, or NULL_TREE if no folding opportunity is found. */
5103 static tree
5105 {
5110 tree tem;
5115 /* If we have A op 0 ? A : -A, consider applying the following
5116 transformations:
5118 A == 0? A : -A same as -A
5119 A != 0? A : -A same as A
5120 A >= 0? A : -A same as abs (A)
5121 A > 0? A : -A same as abs (A)
5122 A <= 0? A : -A same as -abs (A)
5123 A < 0? A : -A same as -abs (A)
5125 None of these transformations work for modes with signed
5126 zeros. If A is +/-0, the first two transformations will
5127 change the sign of the result (from +0 to -0, or vice
5128 versa). The last four will fix the sign of the result,
5129 even though the original expressions could be positive or
5130 negative, depending on the sign of A.
5132 Note that all these transformations are correct if A is
5133 NaN, since the two alternatives (A and -A) are also NaNs. */
5140 /* In the case that A is of the form X-Y, '-A' (arg2) may
5141 have already been folded to Y-X, check for that. */
5149 {
5161 /* Fall through. */
5183 }
5185 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5186 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5187 both transformations are correct when A is NaN: A != 0
5188 is then true, and A == 0 is false. */
5192 {
5197 }
5199 /* Try some transformations of A op B ? A : B.
5201 A == B? A : B same as B
5202 A != B? A : B same as A
5203 A >= B? A : B same as max (A, B)
5204 A > B? A : B same as max (B, A)
5205 A <= B? A : B same as min (A, B)
5206 A < B? A : B same as min (B, A)
5208 As above, these transformations don't work in the presence
5209 of signed zeros. For example, if A and B are zeros of
5210 opposite sign, the first two transformations will change
5211 the sign of the result. In the last four, the original
5212 expressions give different results for (A=+0, B=-0) and
5213 (A=-0, B=+0), but the transformed expressions do not.
5215 The first two transformations are correct if either A or B
5216 is a NaN. In the first transformation, the condition will
5217 be false, and B will indeed be chosen. In the case of the
5218 second transformation, the condition A != B will be true,
5219 and A will be chosen.
5221 The conversions to max() and min() are not correct if B is
5222 a number and A is not. The conditions in the original
5223 expressions will be false, so all four give B. The min()
5224 and max() versions would give a NaN instead. */
5227 /* Avoid these transformations if the COND_EXPR may be used
5228 as an lvalue in the C++ front-end. PR c++/19199. */
5229 && (in_gimple_form
5234 {
5239 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5241 {
5245 }
5248 {
5257 /* In C++ a ?: expression can be an lvalue, so put the
5258 operand which will be used if they are equal first
5259 so that we can convert this back to the
5260 corresponding COND_EXPR. */
5262 {
5269 }
5276 {
5283 }
5296 }
5297 }
5299 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5300 we might still be able to simplify this. For example,
5301 if C1 is one less or one more than C2, this might have started
5302 out as a MIN or MAX and been transformed by this function.
5303 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5309 {
5311 /* We can replace A with C1 in this case. */
5316 /* If C1 is C2 + 1, this is min(A, C2). */
5318 OEP_ONLY_CONST)
5322 OEP_ONLY_CONST))
5324 type,
5326 arg2));
5330 /* If C1 is C2 - 1, this is min(A, C2). */
5332 OEP_ONLY_CONST)
5336 OEP_ONLY_CONST))
5338 type,
5340 arg2));
5344 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5345 MAX_EXPR, to preserve the signedness of the comparison. */
5347 OEP_ONLY_CONST)
5351 OEP_ONLY_CONST))
5354 arg00,
5356 arg2))));
5360 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5362 OEP_ONLY_CONST)
5366 OEP_ONLY_CONST))
5369 arg00,
5371 arg2))));
5377 }
5380 }
5383 \f
5384 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5385 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5386 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5387 false) >= 2)
5388 #endif
5390 /* EXP is some logical combination of boolean tests. See if we can
5391 merge it into some range test. Return the new tree if so. */
5393 static tree
5395 {
5403 tree tem;
5407 /* If this is an OR operation, invert both sides; we will invert
5408 again at the end. */
5412 /* If both expressions are the same, if we can merge the ranges, and we
5413 can build the range test, return it or it inverted. If one of the
5414 ranges is always true or always false, consider it to be the same
5415 expression as the other. */
5423 {
5427 }
5429 /* On machines where the branch cost is expensive, if this is a
5430 short-circuited branch and the underlying object on both sides
5431 is the same, make a non-short-circuit operation. */
5437 {
5438 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5439 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5440 which cases we can't do this. */
5448 {
5457 {
5460 WARN_STRICT_OVERFLOW_COMPARISON);
5464 }
5465 }
5466 }
5469 }
5470 \f
5471 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5472 bit value. Arrange things so the extra bits will be set to zero if and
5473 only if C is signed-extended to its full width. If MASK is nonzero,
5474 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5476 static tree
5478 {
5481 tree temp;
5486 /* We work by getting just the sign bit into the low-order bit, then
5487 into the high-order bit, then sign-extend. We then XOR that value
5488 with C. */
5492 /* We must use a signed type in order to get an arithmetic right shift.
5493 However, we must also avoid introducing accidental overflows, so that
5494 a subsequent call to integer_zerop will work. Hence we must
5495 do the type conversion here. At this point, the constant is either
5496 zero or one, and the conversion to a signed type can never overflow.
5497 We could get an overflow if this conversion is done anywhere else. */
5506 /* If necessary, convert the type back to match the type of C. */
5511 }
5512 \f
5513 /* Find ways of folding logical expressions of LHS and RHS:
5514 Try to merge two comparisons to the same innermost item.
5515 Look for range tests like "ch >= '0' && ch <= '9'".
5516 Look for combinations of simple terms on machines with expensive branches
5517 and evaluate the RHS unconditionally.
5519 For example, if we have p->a == 2 && p->b == 4 and we can make an
5520 object large enough to span both A and B, we can do this with a comparison
5521 against the object ANDed with the a mask.
5523 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5524 operations to do this with one comparison.
5526 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5527 function and the one above.
5529 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5530 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5532 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5533 two operands.
5535 We return the simplified tree or 0 if no optimization is possible. */
5537 static tree
5539 {
5540 /* If this is the "or" of two comparisons, we can do something if
5541 the comparisons are NE_EXPR. If this is the "and", we can do something
5542 if the comparisons are EQ_EXPR. I.e.,
5543 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5545 WANTED_CODE is this operation code. For single bit fields, we can
5546 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5547 comparison for one-bit fields. */
5569 /* Start by getting the comparison codes. Fail if anything is volatile.
5570 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5571 it were surrounded with a NE_EXPR. */
5580 {
5584 }
5587 {
5591 }
5602 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5605 {
5606 tree result;
5609 {
5614 }
5617 {
5623 }
5624 }
5629 /* If the RHS can be evaluated unconditionally and its operands are
5630 simple, it wins to evaluate the RHS unconditionally on machines
5631 with expensive branches. In this case, this isn't a comparison
5632 that can be merged. Avoid doing this if the RHS is a floating-point
5633 comparison since those can trap. */
5640 {
5641 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5652 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5664 {
5668 }
5669 }
5671 /* See if the comparisons can be merged. Then get all the parameters for
5672 each side. */
5696 /* It must be true that the inner operation on the lhs of each
5697 comparison must be the same if we are to be able to do anything.
5698 Then see if we have constants. If not, the same must be true for
5699 the rhs's. */
5710 else
5713 /* If either comparison code is not correct for our logical operation,
5714 fail. However, we can convert a one-bit comparison against zero into
5715 the opposite comparison against that bit being set in the field. */
5719 {
5721 {
5722 /* Make the left operand unsigned, since we are only interested
5723 in the value of one bit. Otherwise we are doing the wrong
5724 thing below. */
5727 }
5728 else
5730 }
5732 /* This is analogous to the code for l_const above. */
5734 {
5736 {
5739 }
5740 else
5742 }
5744 /* See if we can find a mode that contains both fields being compared on
5745 the left. If we can't, fail. Otherwise, update all constants and masks
5746 to be relative to a field of that size. */
5751 volatilep);
5761 {
5764 }
5772 {
5780 {
5784 }
5785 }
5787 {
5795 {
5799 }
5800 }
5802 /* If the right sides are not constant, do the same for it. Also,
5803 disallow this optimization if a size or signedness mismatch occurs
5804 between the left and right sides. */
5806 {
5809 /* Make sure the two fields on the right
5810 correspond to the left without being swapped. */
5818 volatilep);
5828 {
5831 }
5838 /* Make a mask that corresponds to both fields being compared.
5839 Do this for both items being compared. If the operands are the
5840 same size and the bits being compared are in the same position
5841 then we can do this by masking both and comparing the masked
5842 results. */
5846 {
5858 }
5860 /* There is still another way we can do something: If both pairs of
5861 fields being compared are adjacent, we may be able to make a wider
5862 field containing them both.
5864 Note that we still must mask the lhs/rhs expressions. Furthermore,
5865 the mask must be shifted to account for the shift done by
5866 make_bit_field_ref. */
5871 {
5872 tree type;
5884 /* Convert to the smaller type before masking out unwanted bits. */
5887 {
5889 {
5893 }
5895 {
5899 }
5900 }
5909 }
5912 }
5914 /* Handle the case of comparisons with constants. If there is something in
5915 common between the masks, those bits of the constants must be the same.
5916 If not, the condition is always false. Test for this to avoid generating
5917 incorrect code below. */
5922 {
5924 {
5927 }
5928 else
5929 {
5932 }
5933 }
5935 /* Construct the expression we will return. First get the component
5936 reference we will make. Unless the mask is all ones the width of
5937 that field, perform the mask operation. Then compare with the
5938 merged constant. */
5948 }
5949 \f
5950 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5951 constant. */
5953 static tree
5955 {
5958 tree comp_const;
5959 tree minmax_const;
5961 tree inner;
5972 /* If something does not permit us to optimize, return the original tree. */
5980 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5981 and GT_EXPR, doing the rest with recursive calls using logical
5982 simplifications. */
5984 {
5986 {
5992 }
5995 return
5997 optimize_minmax_comparison
5999 optimize_minmax_comparison
6004 /* MAX (X, 0) == 0 -> X <= 0 */
6008 /* MAX (X, 0) == 5 -> X == 5 */
6012 /* MAX (X, 0) == -1 -> false */
6016 /* MIN (X, 0) == 0 -> X >= 0 */
6020 /* MIN (X, 0) == 5 -> false */
6023 else
6024 /* MIN (X, 0) == -1 -> X == -1 */
6029 /* MAX (X, 0) > 0 -> X > 0
6030 MAX (X, 0) > 5 -> X > 5 */
6034 /* MAX (X, 0) > -1 -> true */
6038 /* MIN (X, 0) > 0 -> false
6039 MIN (X, 0) > 5 -> false */
6042 else
6043 /* MIN (X, 0) > -1 -> X > -1 */
6048 }
6049 }
6050 \f
6051 /* T is an integer expression that is being multiplied, divided, or taken a
6052 modulus (CODE says which and what kind of divide or modulus) by a
6053 constant C. See if we can eliminate that operation by folding it with
6054 other operations already in T. WIDE_TYPE, if non-null, is a type that
6055 should be used for the computation if wider than our type.
6057 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6058 (X * 2) + (Y * 4). We must, however, be assured that either the original
6059 expression would not overflow or that overflow is undefined for the type
6060 in the language in question.
6062 If we return a non-null expression, it is an equivalent form of the
6063 original computation, but need not be in the original type.
6065 We set *STRICT_OVERFLOW_P to true if the return values depends on
6066 signed overflow being undefined. Otherwise we do not change
6067 *STRICT_OVERFLOW_P. */
6069 static tree
6072 {
6073 /* To avoid exponential search depth, refuse to allow recursion past
6074 three levels. Beyond that (1) it's highly unlikely that we'll find
6075 something interesting and (2) we've probably processed it before
6076 when we built the inner expression. */
6079 tree ret;
6084 depth++;
6086 depth--;
6089 }
6091 static tree
6094 {
6105 /* Don't deal with constants of zero here; they confuse the code below. */
6115 /* Note that we need not handle conditional operations here since fold
6116 already handles those cases. So just do arithmetic here. */
6118 {
6120 /* For a constant, we can always simplify if we are a multiply
6121 or (for divide and modulus) if it is a multiple of our constant. */
6129 /* If op0 is an expression ... */
6135 /* ... and has wrapping overflow, and its type is smaller
6136 than ctype, then we cannot pass through as widening. */
6142 /* ... or this is a truncation (t is narrower than op0),
6143 then we cannot pass through this narrowing. */
6146 /* ... or signedness changes for division or modulus,
6147 then we cannot pass through this conversion. */
6151 /* ... or has undefined overflow while the converted to
6152 type has not, we cannot do the operation in the inner type
6153 as that would introduce undefined overflow. */
6158 /* Pass the constant down and see if we can make a simplification. If
6159 we can, replace this expression with the inner simplification for
6160 possible later conversion to our or some other type. */
6165 code == MULT_EXPR
6167 strict_overflow_p))))
6172 /* If widening the type changes it from signed to unsigned, then we
6173 must avoid building ABS_EXPR itself as unsigned. */
6175 {
6179 {
6182 }
6184 }
6185 /* If the constant is negative, we cannot simplify this. */
6188 /* FALLTHROUGH */
6196 /* If widening the type changes the signedness, then we can't perform
6197 this optimization as that changes the result. */
6201 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6207 {
6214 }
6218 /* If the second operand is constant, this is a multiplication
6219 or floor division, by a power of two, so we can treat it that
6220 way unless the multiplier or divisor overflows. Signed
6221 left-shift overflow is implementation-defined rather than
6222 undefined in C90, so do not convert signed left shift into
6223 multiplication. */
6226 /* const_binop may not detect overflow correctly,
6227 so check for it explicitly here. */
6232 size_one_node,
6242 /* See if we can eliminate the operation on both sides. If we can, we
6243 can return a new PLUS or MINUS. If we can't, the only remaining
6244 cases where we can do anything are if the second operand is a
6245 constant. */
6251 /* If not multiplication, we can only do this if both operands
6252 are divisible by c. */
6255 {
6260 }
6262 /* If this was a subtraction, negate OP1 and set it to be an addition.
6263 This simplifies the logic below. */
6270 /* If either OP1 or C are negative, this optimization is not safe for
6271 some of the division and remainder types while for others we need
6272 to change the code. */
6274 {
6282 }
6284 /* If it's a multiply or a division/modulus operation of a multiple
6285 of our constant, do the operation and verify it doesn't overflow. */
6288 {
6291 /* We allow the constant to overflow with wrapping semantics. */
6295 }
6296 else
6299 /* If we have an unsigned type is not a sizetype, we cannot widen
6300 the operation since it will change the result if the original
6301 computation overflowed. */
6307 /* If we were able to eliminate our operation from the first side,
6308 apply our operation to the second side and reform the PLUS. */
6312 /* The last case is if we are a multiply. In that case, we can
6313 apply the distributive law to commute the multiply and addition
6314 if the multiplication of the constants doesn't overflow. */
6320 op1);
6325 /* We have a special case here if we are doing something like
6326 (C * 8) % 4 since we know that's zero. */
6329 /* If the multiplication can overflow we cannot optimize this.
6330 ??? Until we can properly mark individual operations as
6331 not overflowing we need to treat sizetype special here as
6332 stor-layout relies on this opimization to make
6333 DECL_FIELD_BIT_OFFSET always a constant. */
6339 {
6342 }
6344 /* ... fall through ... */
6348 /* If we can extract our operation from the LHS, do so and return a
6349 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6350 do something only if the second operand is a constant. */
6364 /* If these are the same operation types, we can associate them
6365 assuming no overflow. */
6377 /* If these operations "cancel" each other, we have the main
6378 optimizations of this pass, which occur when either constant is a
6379 multiple of the other, in which case we replace this with either an
6380 operation or CODE or TCODE.
6382 If we have an unsigned type that is not a sizetype, we cannot do
6383 this since it will change the result if the original computation
6384 overflowed. */
6392 {
6394 {
6401 }
6403 {
6410 }
6411 }
6416 }
6419 }
6420 \f
6421 /* Return a node which has the indicated constant VALUE (either 0 or
6422 1), and is of the indicated TYPE. */
6424 tree
6426 {
6431 else
6433 }
6436 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6437 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6438 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6439 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6440 COND is the first argument to CODE; otherwise (as in the example
6441 given here), it is the second argument. TYPE is the type of the
6442 original expression. Return NULL_TREE if no simplification is
6443 possible. */
6445 static tree
6449 {
6456 /* This transformation is only worthwhile if we don't have to wrap
6457 arg in a SAVE_EXPR, and the operation can be simplified on at least
6458 one of the branches once its pushed inside the COND_EXPR. */
6463 {
6467 /* If this operand throws an expression, then it does not make
6468 sense to try to perform a logical or arithmetic operation
6469 involving it. */
6474 }
6475 else
6476 {
6481 }
6485 {
6489 else
6491 }
6493 {
6497 else
6499 }
6503 }
6505 \f
6506 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6508 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6509 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6510 ADDEND is the same as X.
6512 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6513 and finite. The problematic cases are when X is zero, and its mode
6514 has signed zeros. In the case of rounding towards -infinity,
6515 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6516 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6518 bool
6520 {
6524 /* Don't allow the fold with -fsignaling-nans. */
6528 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6532 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6537 /* The mode has signed zeros, and we have to honor their sign.
6538 In this situation, there is only one case we can return true for.
6539 X - 0 is the same as X unless rounding towards -infinity is
6540 supported. */
6542 }
6544 /* Subroutine of fold() that checks comparisons of built-in math
6545 functions against real constants.
6547 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6548 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6549 is the type of the result and ARG0 and ARG1 are the operands of the
6550 comparison. ARG1 must be a TREE_REAL_CST.
6552 The function returns the constant folded tree if a simplification
6553 can be made, and NULL_TREE otherwise. */
6555 static tree
6558 {
6559 REAL_VALUE_TYPE c;
6562 {
6568 {
6569 /* sqrt(x) < y is always false, if y is negative. */
6573 /* sqrt(x) > y is always true, if y is negative and we
6574 don't care about NaNs, i.e. negative values of x. */
6578 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6581 }
6583 {
6584 REAL_VALUE_TYPE c2;
6590 {
6591 /* sqrt(x) > y is x == +Inf, when y is very large. */
6596 /* sqrt(x) > y is always false, when y is very large
6597 and we don't care about infinities. */
6599 }
6601 /* sqrt(x) > c is the same as x > c*c. */
6604 }
6606 {
6607 REAL_VALUE_TYPE c2;
6613 {
6614 /* sqrt(x) < y is always true, when y is a very large
6615 value and we don't care about NaNs or Infinities. */
6619 /* sqrt(x) < y is x != +Inf when y is very large and we
6620 don't care about NaNs. */
6625 /* sqrt(x) < y is x >= 0 when y is very large and we
6626 don't care about Infinities. */
6631 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6640 dconst0)),
6643 c2)));
6644 }
6646 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6651 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6654 {
6659 dconst0)),
6662 c2)));
6663 }
6664 }
6665 }
6668 }
6670 /* Subroutine of fold() that optimizes comparisons against Infinities,
6671 either +Inf or -Inf.
6673 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6674 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6675 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6677 The function returns the constant folded tree if a simplification
6678 can be made, and NULL_TREE otherwise. */
6680 static tree
6682 {
6684 REAL_VALUE_TYPE max;
6685 tree temp;
6690 /* For negative infinity swap the sense of the comparison. */
6696 {
6698 /* x > +Inf is always false, if with ignore sNANs. */
6704 /* x <= +Inf is always true, if we don't case about NaNs. */
6708 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6711 {
6714 }
6719 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6725 /* x < +Inf is always equal to x <= DBL_MAX. */
6731 /* x != +Inf is always equal to !(x > DBL_MAX). */
6743 }
6746 }
6748 /* Subroutine of fold() that optimizes comparisons of a division by
6749 a nonzero integer constant against an integer constant, i.e.
6750 X/C1 op C2.
6752 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6753 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6754 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6756 The function returns the constant folded tree if a simplification
6757 can be made, and NULL_TREE otherwise. */
6759 static tree
6761 {
6766 HOST_WIDE_INT hpart;
6771 /* We have to do this the hard way to detect unsigned overflow.
6772 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6783 {
6788 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6796 }
6798 {
6802 {
6821 }
6822 }
6823 else
6824 {
6825 /* A negative divisor reverses the relational operators. */
6831 {
6850 }
6851 }
6854 {
6875 {
6878 }
6883 {
6886 }
6891 {
6894 }
6899 {
6902 }
6907 }
6910 }
6913 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6914 equality/inequality test, then return a simplified form of the test
6915 using a sign testing. Otherwise return NULL. TYPE is the desired
6916 result type. */
6918 static tree
6920 tree result_type)
6921 {
6922 /* If this is testing a single bit, we can optimize the test. */
6926 {
6927 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6928 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6932 /* This is only a win if casting to a signed type is cheap,
6933 i.e. when arg00's type is not a partial mode. */
6936 {
6941 }
6942 }
6945 }
6947 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6948 equality/inequality test, then return a simplified form of
6949 the test using shifts and logical operations. Otherwise return
6950 NULL. TYPE is the desired result type. */
6952 tree
6954 tree result_type)
6955 {
6956 /* If this is testing a single bit, we can optimize the test. */
6960 {
6969 /* First, see if we can fold the single bit test into a sign-bit
6970 test. */
6972 result_type);
6976 /* Otherwise we have (A & C) != 0 where C is a single bit,
6977 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6978 Similarly for (A & C) == 0. */
6980 /* If INNER is a right shift of a constant and it plus BITNUM does
6981 not overflow, adjust BITNUM and INNER. */
6988 {
6991 }
6993 /* If we are going to be able to omit the AND below, we must do our
6994 operations as unsigned. If we must use the AND, we have a choice.
6995 Normally unsigned is faster, but for some machines signed is. */
6996 #ifdef LOAD_EXTEND_OP
6999 #else
7001 #endif
7017 /* Put the AND last so it can combine with more things. */
7020 /* Make sure to return the proper type. */
7024 }
7026 }
7028 /* Check whether we are allowed to reorder operands arg0 and arg1,
7029 such that the evaluation of arg1 occurs before arg0. */
7031 static bool
7033 {
7040 }
7042 /* Test whether it is preferable two swap two operands, ARG0 and
7043 ARG1, for example because ARG0 is an integer constant and ARG1
7044 isn't. If REORDER is true, only recommend swapping if we can
7045 evaluate the operands in reverse order. */
7047 bool
7049 {
7085 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7086 for commutative and comparison operators. Ensuring a canonical
7087 form allows the optimizers to find additional redundancies without
7088 having to explicitly check for both orderings. */
7094 /* Put SSA_NAMEs last. */
7100 /* Put variables last. */
7107 }
7109 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7110 ARG0 is extended to a wider type. */
7112 static tree
7114 {
7116 tree arg1_unw;
7125 #ifdef HAVE_canonicalize_funcptr_for_compare
7126 /* Disable this optimization if we're casting a function pointer
7127 type on targets that require function pointer canonicalization. */
7132 #endif
7139 /* If possible, express the comparison in the shorter mode. */
7159 /* If we are comparing with the integer that does not fit into the range
7160 of the shorter type, the result is known. */
7171 {
7198 }
7201 }
7203 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7204 ARG0 just the signedness is changed. */
7206 static tree
7209 {
7210 tree arg0_inner;
7220 #ifdef HAVE_canonicalize_funcptr_for_compare
7221 /* Disable this optimization if we're casting a function pointer
7222 type on targets that require function pointer canonicalization. */
7227 #endif
7232 /* If the conversion is from an integral subtype to its basetype
7233 leave it alone. */
7252 else
7256 }
7258 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7259 step of the array. Reconstructs s and delta in the case of s * delta
7260 being an integer constant (and thus already folded).
7261 ADDR is the address. MULT is the multiplicative expression.
7262 If the function succeeds, the new address expression is returned. Otherwise
7263 NULL_TREE is returned. */
7265 static tree
7267 {
7271 tree itype;
7274 /* Strip the nops that might be added when converting op1 to sizetype. */
7277 /* Canonicalize op1 into a possibly non-constant delta
7278 and an INTEGER_CST s. */
7280 {
7287 {
7290 }
7292 {
7295 }
7296 else
7298 }
7300 {
7303 }
7304 else
7305 {
7306 /* Simulate we are delta * 1. */
7309 }
7312 {
7314 {
7315 /* Remember if this was a multi-dimensional array. */
7328 {
7331 }
7332 else
7333 {
7334 /* Try if delta is a multiple of step. */
7339 }
7341 /* Only fold here if we can verify we do not overflow one
7342 dimension of a multi-dimensional array. */
7344 {
7345 tree tmp;
7361 }
7364 }
7365 else
7370 }
7372 /* We found the suitable array reference. So copy everything up to it,
7373 and replace the index. */
7380 {
7384 }
7392 }
7395 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7396 means A >= Y && A != MAX, but in this case we know that
7397 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7399 static tree
7401 {
7408 else
7417 {
7420 }
7422 {
7425 }
7426 else
7433 {
7434 /* Convert the pointer types into integer before taking the difference. */
7438 }
7439 else
7446 }
7448 /* Fold a sum or difference of at least one multiplication.
7449 Returns the folded tree or NULL if no simplification could be made. */
7451 static tree
7453 {
7457 /* (A * C) +- (B * C) -> (A+-B) * C.
7458 (A * C) +- A -> A * (C+-1).
7459 We are most concerned about the case where C is a constant,
7460 but other combinations show up during loop reduction. Since
7461 it is not difficult, try all four possibilities. */
7464 {
7467 }
7469 {
7472 }
7473 else
7474 {
7475 /* We cannot generate constant 1 for fract. */
7480 }
7482 {
7485 }
7487 {
7489 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7490 the purpose of this canonicalization. */
7494 {
7497 }
7498 else
7500 }
7501 else
7502 {
7503 /* We cannot generate constant 1 for fract. */
7508 }
7520 /* No identical multiplicands; see if we can find a common
7521 power-of-two factor in non-power-of-two multiplies. This
7522 can help in multi-dimensional array access. */
7525 {
7528 tree maybe_same;
7532 /* Move min of absolute values to int11. */
7535 {
7540 }
7541 else
7545 /* The remainder should not be a constant, otherwise we
7546 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7547 increased the number of multiplications necessary. */
7549 {
7557 }
7558 }
7568 }
7570 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7571 specified by EXPR into the buffer PTR of length LEN bytes.
7572 Return the number of bytes placed in the buffer, or zero
7573 upon failure. */
7575 static int
7577 {
7588 {
7592 else
7597 {
7604 else
7606 }
7607 else
7610 }
7612 }
7615 /* Subroutine of native_encode_expr. Encode the REAL_CST
7616 specified by EXPR into the buffer PTR of length LEN bytes.
7617 Return the number of bytes placed in the buffer, or zero
7618 upon failure. */
7620 static int
7622 {
7628 /* There are always 32 bits in each long, no matter the size of
7629 the hosts long. We handle floating point representations with
7630 up to 192 bits. */
7641 {
7646 {
7653 else
7655 }
7656 else
7659 }
7661 }
7663 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7664 specified by EXPR into the buffer PTR of length LEN bytes.
7665 Return the number of bytes placed in the buffer, or zero
7666 upon failure. */
7668 static int
7670 {
7672 tree part;
7683 }
7686 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7687 specified by EXPR into the buffer PTR of length LEN bytes.
7688 Return the number of bytes placed in the buffer, or zero
7689 upon failure. */
7691 static int
7693 {
7703 {
7705 {
7708 }
7709 else
7713 {
7716 }
7717 else
7718 {
7722 }
7724 }
7726 }
7729 /* Subroutine of native_encode_expr. Encode the STRING_CST
7730 specified by EXPR into the buffer PTR of length LEN bytes.
7731 Return the number of bytes placed in the buffer, or zero
7732 upon failure. */
7734 static int
7736 {
7738 HOST_WIDE_INT total_bytes;
7749 {
7753 }
7754 else
7757 }
7760 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7761 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7762 buffer PTR of length LEN bytes. Return the number of bytes
7763 placed in the buffer, or zero upon failure. */
7765 int
7767 {
7769 {
7787 }
7788 }
7791 /* Subroutine of native_interpret_expr. Interpret the contents of
7792 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7793 If the buffer cannot be interpreted, return NULL_TREE. */
7795 static tree
7797 {
7811 {
7814 {
7821 else
7823 }
7824 else
7830 else
7833 }
7836 }
7839 /* Subroutine of native_interpret_expr. Interpret the contents of
7840 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7841 If the buffer cannot be interpreted, return NULL_TREE. */
7843 static tree
7845 {
7850 /* There are always 32 bits in each long, no matter the size of
7851 the hosts long. We handle floating point representations with
7852 up to 192 bits. */
7853 REAL_VALUE_TYPE r;
7864 {
7867 {
7874 else
7876 }
7877 else
7882 }
7886 }
7889 /* Subroutine of native_interpret_expr. Interpret the contents of
7890 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7891 If the buffer cannot be interpreted, return NULL_TREE. */
7893 static tree
7895 {
7910 }
7913 /* Subroutine of native_interpret_expr. Interpret the contents of
7914 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7915 If the buffer cannot be interpreted, return NULL_TREE. */
7917 static tree
7919 {
7931 {
7936 }
7938 }
7941 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7942 the buffer PTR of length LEN as a constant of type TYPE. For
7943 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7944 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7945 return NULL_TREE. */
7947 tree
7949 {
7951 {
7968 }
7969 }
7972 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7973 TYPE at compile-time. If we're unable to perform the conversion
7974 return NULL_TREE. */
7976 static tree
7978 {
7979 /* We support up to 512-bit values (for V8DFmode). */
7983 /* Check that the host and target are sane. */
7992 }
7994 /* Build an expression for the address of T. Folds away INDIRECT_REF
7995 to avoid confusing the gimplify process. */
7997 tree
7999 {
8000 /* The size of the object is not relevant when talking about its address. */
8004 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
8007 {
8012 }
8013 else
8017 }
8019 /* Build an expression for the address of T. */
8021 tree
8023 {
8027 }
8029 /* Fold a unary expression of code CODE and type TYPE with operand
8030 OP0. Return the folded expression if folding is successful.
8031 Otherwise, return NULL_TREE. */
8033 tree
8035 {
8036 tree tem;
8037 tree arg0;
8045 {
8048 {
8049 /* Don't use STRIP_NOPS, because signedness of argument type
8050 matters. */
8052 }
8053 else
8054 {
8055 /* Strip any conversions that don't change the mode. This
8056 is safe for every expression, except for a comparison
8057 expression because its signedness is derived from its
8058 operands.
8060 Note that this is done as an internal manipulation within
8061 the constant folder, in order to find the simplest
8062 representation of the arguments so that their form can be
8063 studied. In any cases, the appropriate type conversions
8064 should be put back in the tree that will get out of the
8065 constant folder. */
8067 }
8068 }
8071 {
8078 {
8090 /* If this was a conversion, and all we did was to move into
8091 inside the COND_EXPR, bring it back out. But leave it if
8092 it is a conversion from integer to integer and the
8093 result precision is no wider than a word since such a
8094 conversion is cheap and may be optimized away by combine,
8095 while it couldn't if it were outside the COND_EXPR. Then return
8096 so we don't get into an infinite recursion loop taking the
8097 conversion out and then back in. */
8109 && (INTEGRAL_TYPE_P
8121 }
8123 {
8125 {
8129 }
8133 integer_one_node),
8135 integer_zero_node));
8136 }
8137 }
8140 {
8142 /* Re-association barriers around constants and other re-association
8143 barriers can be removed. */
8149 CASE_CONVERT:
8155 /* If we have (type) (a CMP b) and type is an integral type, return
8156 new expression involving the new type. */
8161 /* Handle cases of two conversions in a row. */
8163 {
8185 /* In addition to the cases of two conversions in a row
8186 handled below, if we are converting something to its own
8187 type via an object of identical or wider precision, neither
8188 conversion is needed. */
8195 /* Likewise, if the intermediate and initial types are either both
8196 float or both integer, we don't need the middle conversion if the
8197 former is wider than the latter and doesn't change the signedness
8198 (for integers). Avoid this if the final type is a pointer since
8199 then we sometimes need the middle conversion. Likewise if the
8200 final type has a precision not equal to the size of its mode. */
8209 && ! final_ptr
8213 /* If we have a sign-extension of a zero-extended value, we can
8214 replace that by a single zero-extension. */
8220 /* Two conversions in a row are not needed unless:
8221 - some conversion is floating-point (overstrict for now), or
8222 - some conversion is a vector (overstrict for now), or
8223 - the intermediate type is narrower than both initial and
8224 final, or
8225 - the intermediate type and innermost type differ in signedness,
8226 and the outermost type is wider than the intermediate, or
8227 - the initial type is a pointer type and the precisions of the
8228 intermediate and final types differ, or
8229 - the final type is a pointer type and the precisions of the
8230 initial and intermediate types differ. */
8244 }
8246 /* Handle (T *)&A.B.C for A being of type T and B and C
8247 living at offset zero. This occurs frequently in
8248 C++ upcasting and then accessing the base. */
8252 {
8254 tree offset;
8260 /* If the reference was to a (constant) zero offset, we can use
8261 the address of the base if it has the same base type
8262 as the result type. */
8267 }
8271 /* Detect assigning a bitfield. */
8273 && DECL_BIT_FIELD
8275 {
8276 /* Don't leave an assignment inside a conversion
8277 unless assigning a bitfield. */
8279 /* First do the assignment, then return converted constant. */
8284 }
8286 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8287 constants (if x has signed type, the sign bit cannot be set
8288 in c). This folds extension into the BIT_AND_EXPR.
8289 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8290 very likely don't have maximal range for their precision and this
8291 transformation effectively doesn't preserve non-maximal ranges. */
8295 /* Not if the conversion is to the sub-type. */
8297 {
8307 <= HOST_BITS_PER_WIDE_INT
8309 {
8316 #ifdef LOAD_EXTEND_OP
8318 && !flag_syntax_only
8321 {
8325 }
8326 #endif
8327 }
8329 {
8335 }
8336 }
8338 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8339 when one of the new casts will fold away. Conservatively we assume
8340 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8346 {
8352 }
8354 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8355 of the same precision, and X is an integer type not narrower than
8356 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8362 {
8367 }
8369 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8370 type of X and Y (integer types only). */
8375 {
8376 /* Be careful not to introduce new overflows. */
8377 tree mult_type;
8380 else
8384 {
8391 }
8392 }
8407 /* For integral conversions with the same precision or pointer
8408 conversions use a NOP_EXPR instead. */
8414 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8415 a sub-type to its base type as generated by the Ada FE. */
8420 /* Strip inner integral conversions that do not change the precision. */
8443 /* Convert fabs((double)float) into (double)fabsf(float). */
8446 {
8451 targ0));
8452 }
8453 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8459 /* Strip sign ops from argument. */
8461 {
8465 }
8472 {
8477 }
8479 {
8484 }
8494 /* Convert ~ (-A) to A - 1. */
8499 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8507 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8520 /* Perform BIT_NOT_EXPR on each element individually. */
8522 {
8527 {
8529 {
8535 }
8536 else
8539 }
8542 }
8547 /* The argument to invert_truthvalue must have Boolean type. */
8551 /* Note that the operand of this must be an int
8552 and its values must be 0 or 1.
8553 ("true" is a fixed value perhaps depending on the language,
8554 but we don't handle values other than 1 correctly yet.) */
8569 {
8577 }
8579 {
8583 }
8585 {
8589 {
8598 }
8599 }
8611 {
8619 }
8621 {
8625 }
8627 {
8631 {
8640 }
8641 }
8647 }
8650 /* If the operation was a conversion do _not_ mark a resulting constant
8651 with TREE_OVERFLOW if the original constant was not. These conversions
8652 have implementation defined behavior and retaining the TREE_OVERFLOW
8653 flag here would confuse later passes such as VRP. */
8654 tree
8656 {
8665 }
8667 /* Fold a binary expression of code CODE and type TYPE with operands
8668 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8669 Return the folded expression if folding is successful. Otherwise,
8670 return NULL_TREE. */
8672 static tree
8674 {
8681 else
8684 /* MIN (MAX (a, b), b) == b. */
8689 /* MIN (MAX (b, a), b) == b. */
8695 /* MIN (a, MAX (a, b)) == a. */
8701 /* MIN (a, MAX (b, a)) == a. */
8708 }
8710 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8711 by changing CODE to reduce the magnitude of constants involved in
8712 ARG0 of the comparison.
8713 Returns a canonicalized comparison tree if a simplification was
8714 possible, otherwise returns NULL_TREE.
8715 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8716 valid if signed overflow is undefined. */
8718 static tree
8722 {
8728 /* Match A +- CST code arg1 and CST code arg1. We can change the
8729 first form only if overflow is undefined. */
8731 /* In principle pointers also have undefined overflow behavior,
8732 but that causes problems elsewhere. */
8740 /* Identify the constant in arg0 and its sign. */
8743 else
8747 /* Overflowed constants and zero will cause problems. */
8752 /* See if we can reduce the magnitude of the constant in
8753 arg0 by changing the comparison code. */
8755 {
8756 /* CST <= arg1 -> CST-1 < arg1. */
8759 /* -CST < arg1 -> -CST-1 <= arg1. */
8762 /* CST > arg1 -> CST-1 >= arg1. */
8765 /* -CST >= arg1 -> -CST-1 > arg1. */
8768 else
8770 /* arg1 code' CST' might be more canonical. */
8772 }
8773 else
8774 {
8775 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8779 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8783 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8787 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8791 else
8794 }
8796 /* Now build the constant reduced in magnitude. But not if that
8797 would produce one outside of its types range. */
8805 /* We cannot swap the comparison here as that would cause us to
8806 endlessly recurse. */
8814 /* If swapping might yield to a more canonical form, do so. */
8817 else
8819 }
8821 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8822 overflow further. Try to decrease the magnitude of constants involved
8823 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8824 and put sole constants at the second argument position.
8825 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8827 static tree
8830 {
8831 tree t;
8836 /* Try canonicalization by simplifying arg0. */
8841 {
8845 }
8847 /* Try canonicalization by simplifying arg1 using the swapped
8848 comparison. */
8856 }
8858 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8859 space. This is used to avoid issuing overflow warnings for
8860 expressions like &p->x which can not wrap. */
8862 static bool
8864 {
8875 {
8878 }
8881 else
8882 {
8885 }
8900 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8901 array. */
8903 {
8904 HOST_WIDE_INT base_size;
8909 }
8912 }
8914 /* Subroutine of fold_binary. This routine performs all of the
8915 transformations that are common to the equality/inequality
8916 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8917 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8918 fold_binary should call fold_binary. Fold a comparison with
8919 tree code CODE and type TYPE with operands OP0 and OP1. Return
8920 the folded comparison or NULL_TREE. */
8922 static tree
8924 {
8937 /* If one arg is a real or integer constant, put it last. */
8941 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8948 {
8952 tree lhs;
8959 /* If the constant operation overflowed this can be
8960 simplified as a comparison against INT_MAX/INT_MIN. */
8963 {
8967 /* Get the sign of the constant on the lhs if the
8968 operation were VARIABLE + CONST1. */
8972 /* The sign of the constant determines if we overflowed
8973 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8974 Canonicalize to the INT_MIN overflow by swapping the comparison
8975 if necessary. */
8979 /* We now can look at the canonicalized case
8980 VARIABLE + 1 CODE2 INT_MIN
8981 and decide on the result. */
8990 }
8995 {
8997 "when changing X +- C1 cmp C2 to "
8999 WARN_STRICT_OVERFLOW_COMPARISON);
9001 }
9002 }
9004 /* For comparisons of pointers we can decompose it to a compile time
9005 comparison of the base objects and the offsets into the object.
9006 This requires at least one operand being an ADDR_EXPR or a
9007 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9013 {
9020 /* Get base and offset for the access. Strip ADDR_EXPR for
9021 get_inner_reference, but put it back by stripping INDIRECT_REF
9022 off the base object if possible. indirect_baseN will be true
9023 if baseN is not an address but refers to the object itself. */
9026 {
9032 else
9034 }
9036 {
9039 }
9043 {
9049 else
9051 }
9053 {
9056 }
9058 /* If we have equivalent bases we might be able to simplify. */
9061 {
9062 /* We can fold this expression to a constant if the non-constant
9063 offset parts are equal. */
9071 {
9078 "occur when comparing P +- C1 with "
9080 WARN_STRICT_OVERFLOW_CONDITIONAL);
9083 {
9097 }
9098 }
9099 /* We can simplify the comparison to a comparison of the variable
9100 offset parts if the constant offset parts are equal.
9101 Be careful to use signed size type here because otherwise we
9102 mess with array offsets in the wrong way. This is possible
9103 because pointer arithmetic is restricted to retain within an
9104 object and overflow on pointer differences is undefined as of
9105 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9109 {
9110 tree signed_size_type_node;
9113 /* By converting to signed size type we cover middle-end pointer
9114 arithmetic which operates on unsigned pointer types of size
9115 type size and ARRAY_REF offsets which are properly sign or
9116 zero extended from their type in case it is narrower than
9117 size type. */
9120 else
9124 else
9132 "occur when comparing P +- C1 with "
9134 WARN_STRICT_OVERFLOW_COMPARISON);
9137 }
9138 }
9139 /* For non-equal bases we can simplify if they are addresses
9140 of local binding decls or constants. */
9142 /* We know that !operand_equal_p (base0, base1, 0)
9143 because the if condition was false. But make
9144 sure two decls are not the same. */
9158 {
9163 }
9164 /* For equal offsets we can simplify to a comparison of the
9165 base addresses. */
9167 && (indirect_base0
9169 && (indirect_base1
9174 {
9180 }
9181 }
9183 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9184 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9185 the resulting offset is smaller in absolute value than the
9186 original one. */
9194 {
9199 tree cst;
9201 "occur when combining constants around "
9204 /* Put the constant on the side where it doesn't overflow and is
9205 of lower absolute value than before. */
9211 {
9214 variable1,
9217 }
9224 {
9229 variable2);
9230 }
9231 }
9233 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9234 signed arithmetic case. That form is created by the compiler
9235 often enough for folding it to be of value. One example is in
9236 computing loop trip counts after Operator Strength Reduction. */
9242 {
9251 "eliminating multiplication in comparison "
9253 WARN_STRICT_OVERFLOW_COMPARISON);
9255 /* If const1 is negative we swap the sense of the comparison. */
9260 }
9267 {
9275 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9280 /* (-a) CMP (-b) -> b CMP a */
9287 {
9288 REAL_VALUE_TYPE cst;
9291 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9298 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9299 /* a CMP (-0) -> a CMP 0 */
9304 /* x != NaN is always true, other ops are always false. */
9307 {
9310 }
9312 /* Fold comparisons against infinity. */
9315 {
9319 }
9320 }
9322 /* If this is a comparison of a real constant with a PLUS_EXPR
9323 or a MINUS_EXPR of a real constant, we can convert it into a
9324 comparison with a revised real constant as long as no overflow
9325 occurs when unsafe_math_optimizations are enabled. */
9337 /* Likewise, we can simplify a comparison of a real constant with
9338 a MINUS_EXPR whose first operand is also a real constant, i.e.
9339 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9340 floating-point types only if -fassociative-math is set. */
9351 /* Fold comparisons against built-in math functions. */
9353 && flag_unsafe_math_optimizations
9355 {
9359 {
9363 }
9364 }
9365 }
9369 {
9370 /* If we are widening one operand of an integer comparison,
9371 see if the other operand is similarly being widened. Perhaps we
9372 can do the comparison in the narrower type. */
9377 /* Or if we are changing signedness. */
9381 }
9383 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9384 constant, we can simplify it. */
9389 {
9393 }
9395 /* Simplify comparison of something with itself. (For IEEE
9396 floating-point, we can only do some of these simplifications.) */
9398 {
9400 {
9415 /* For NE, we can only do this simplification if integer
9416 or we don't honor IEEE floating point NaNs. */
9420 /* ... fall through ... */
9426 }
9427 }
9429 /* If we are comparing an expression that just has comparisons
9430 of two integer values, arithmetic expressions of those comparisons,
9431 and constants, we can simplify it. There are only three cases
9432 to check: the two values can either be equal, the first can be
9433 greater, or the second can be greater. Fold the expression for
9434 those three values. Since each value must be 0 or 1, we have
9435 eight possibilities, each of which corresponds to the constant 0
9436 or 1 or one of the six possible comparisons.
9438 This handles common cases like (a > b) == 0 but also handles
9439 expressions like ((x > y) - (y > x)) > 0, which supposedly
9440 occur in macroized code. */
9443 {
9448 /* Don't handle degenerate cases here; they should already
9449 have been handled anyway. */
9458 {
9462 /* We can't just pass T to eval_subst in case cval1 or cval2
9463 was the same as ARG1. */
9465 tree high_result
9469 arg1);
9470 tree equal_result
9474 arg1);
9475 tree low_result
9479 arg1);
9481 /* All three of these results should be 0 or 1. Confirm they are.
9482 Then use those values to select the proper code to use. */
9487 {
9488 /* Make a 3-bit mask with the high-order bit being the
9489 value for `>', the next for '=', and the low for '<'. */
9493 {
9495 /* Always false. */
9516 /* Always true. */
9518 }
9523 }
9524 }
9525 }
9527 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9528 into a single range test. */
9536 {
9540 }
9542 /* Fold ~X op ~Y as Y op X. */
9545 {
9550 }
9552 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9555 {
9561 }
9564 }
9567 /* Subroutine of fold_binary. Optimize complex multiplications of the
9568 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9569 argument EXPR represents the expression "z" of type TYPE. */
9571 static tree
9573 {
9578 {
9581 }
9583 {
9586 }
9587 else
9588 {
9592 }
9601 }
9604 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9605 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9606 guarantees that P and N have the same least significant log2(M) bits.
9607 N is not otherwise constrained. In particular, N is not normalized to
9608 0 <= N < M as is common. In general, the precise value of P is unknown.
9609 M is chosen as large as possible such that constant N can be determined.
9611 Returns M and sets *RESIDUE to N.
9613 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9614 account. This is not always possible due to PR 35705.
9615 */
9617 static unsigned HOST_WIDE_INT
9620 {
9627 {
9630 {
9632 tree offset;
9640 {
9643 else
9644 /* We don't handle more complicated offset expressions. */
9646 }
9647 }
9652 }
9654 {
9662 allow_func_align);
9668 {
9671 }
9673 {
9676 {
9679 /* Compute the greatest power-of-2 divisor of op1. */
9683 /* If align is non-zero and less than *modulus, replace
9684 *modulus with align., If align is 0, then either op1 is 0
9685 or the greatest power-of-2 divisor of op1 doesn't fit in an
9686 unsigned HOST_WIDE_INT. In either case, no additional
9687 constraint is imposed. */
9692 }
9693 }
9694 }
9696 /* If we get here, we were unable to determine anything useful about the
9697 expression. */
9699 }
9702 /* Fold a binary expression of code CODE and type TYPE with operands
9703 OP0 and OP1. Return the folded expression if folding is
9704 successful. Otherwise, return NULL_TREE. */
9706 tree
9708 {
9722 /* Strip any conversions that don't change the mode. This is
9723 safe for every expression, except for a comparison expression
9724 because its signedness is derived from its operands. So, in
9725 the latter case, only strip conversions that don't change the
9726 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9727 preserved.
9729 Note that this is done as an internal manipulation within the
9730 constant folder, in order to find the simplest representation
9731 of the arguments so that their form can be studied. In any
9732 cases, the appropriate type conversions should be put back in
9733 the tree that will get out of the constant folder. */
9736 {
9739 }
9740 else
9741 {
9744 }
9746 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9747 constant but we can't do arithmetic on them. */
9754 {
9756 {
9757 /* Make sure type and arg0 have the same saturating flag. */
9761 }
9764 else
9768 {
9772 }
9773 }
9775 /* If this is a commutative operation, and ARG0 is a constant, move it
9776 to ARG1 to reduce the number of tests below. */
9781 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9783 First check for cases where an arithmetic operation is applied to a
9784 compound, conditional, or comparison operation. Push the arithmetic
9785 operation inside the compound or conditional to see if any folding
9786 can then be done. Convert comparison to conditional for this purpose.
9787 The also optimizes non-constant cases that used to be done in
9788 expand_expr.
9790 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9791 one of the operands is a comparison and the other is a comparison, a
9792 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9793 code below would make the expression more complex. Change it to a
9794 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9795 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9807 {
9811 boolean_type_node,
9819 }
9823 {
9829 op1));
9838 {
9844 }
9847 {
9853 }
9854 }
9857 {
9859 /* 0 +p index -> (type)index */
9863 /* PTR +p 0 -> PTR */
9867 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9874 /* index +p PTR -> PTR +p index */
9881 /* (PTR +p B) +p A -> PTR +p (B + A) */
9883 {
9884 tree inner;
9892 }
9894 /* PTR_CST +p CST -> CST1 */
9898 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9899 of the array. Loop optimizer sometimes produce this type of
9900 expressions. */
9902 {
9906 }
9911 /* A + (-B) -> A - B */
9916 /* (-A) + B -> B - A */
9924 {
9925 /* Convert ~A + 1 to -A. */
9931 /* ~X + X is -1. */
9934 {
9939 {
9942 }
9943 }
9945 /* X + ~X is -1. */
9948 {
9953 {
9956 }
9957 }
9959 /* X + (X / CST) * -CST is X % CST. */
9964 {
9972 }
9973 }
9975 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9976 same or one. Make sure type is not saturating.
9977 fold_plusminus_mult_expr will re-associate. */
9982 {
9986 }
9989 {
9993 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9994 with a constant, and the two constants have no bits in common,
9995 we should treat this as a BIT_IOR_EXPR since this may produce more
9996 simplifications. */
10004 {
10007 }
10009 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10010 (plus (plus (mult) (mult)) (foo)) so that we can
10011 take advantage of the factoring cases below. */
10018 {
10024 else
10046 parg1)));
10047 }
10048 }
10049 else
10050 {
10051 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10055 /* Likewise if the operands are reversed. */
10059 /* Convert X + -C into X - C. */
10062 {
10068 }
10070 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10071 to __complex__ ( x, y ). This is not the same for SNaNs or
10072 if signed zeros are involved. */
10076 {
10083 {
10087 {
10093 }
10095 {
10101 }
10102 }
10103 }
10111 /* Convert x+x into x*2.0. */
10117 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10118 We associate floats only if the user has specified
10119 -fassociative-math. */
10123 {
10128 {
10129 tree tree0;
10132 }
10133 }
10134 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10135 We associate floats only if the user has specified
10136 -fassociative-math. */
10140 {
10145 {
10146 tree tree0;
10149 }
10150 }
10151 }
10153 bit_rotate:
10154 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10155 is a rotate of A by C1 bits. */
10156 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10157 is a rotate of A by B bits. */
10158 {
10160 tree rtype;
10169 /* Only create rotates in complete modes. Other cases are not
10170 expanded properly. */
10172 {
10191 {
10199 TYPE_PRECISION
10204 ? LROTATE_EXPR
10207 }
10209 {
10217 TYPE_PRECISION
10222 ? LROTATE_EXPR
10225 }
10226 }
10227 }
10229 associate:
10230 /* In most languages, can't associate operations on floats through
10231 parentheses. Rather than remember where the parentheses were, we
10232 don't associate floats at all, unless the user has specified
10233 -fassociative-math.
10234 And, we need to make sure type is not saturating. */
10238 {
10243 /* Split both trees into variables, constants, and literals. Then
10244 associate each group together, the constants with literals,
10245 then the result with variables. This increases the chances of
10246 literals being recombined later and of generating relocatable
10247 expressions for the sum of a constant and literal. */
10252 /* With undefined overflow we can only associate constants
10253 with one variable. */
10257 {
10265 /* The only case we can still associate with two variables
10266 is if they are the same, modulo negation. */
10269 }
10271 /* Only do something if we found more than two objects. Otherwise,
10272 nothing has changed and we risk infinite recursion. */
10278 {
10279 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10288 /* Preserve the MINUS_EXPR if the negative part of the literal is
10289 greater than the positive part. Otherwise, the multiplicative
10290 folding code (i.e extract_muldiv) may be fooled in case
10291 unsigned constants are subtracted, like in the following
10292 example: ((X*2 + 4) - 8U)/2. */
10294 {
10298 {
10302 }
10303 else
10304 {
10308 }
10309 }
10311 {
10316 else
10317 {
10323 }
10324 }
10329 }
10330 }
10335 /* Pointer simplifications for subtraction, simple reassociations. */
10337 {
10338 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10341 {
10349 }
10350 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10352 {
10358 }
10359 }
10360 /* A - (-B) -> A + B */
10364 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10373 /* Convert -A - 1 to ~A. */
10381 /* Convert -1 - A to ~A. */
10387 /* X - (X / CST) * CST is X % CST. */
10400 {
10406 /* Fold A - (A & B) into ~B & A. */
10409 {
10411 {
10416 }
10418 {
10423 }
10424 }
10426 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10427 any power of 2 minus 1. */
10432 {
10438 {
10442 }
10443 }
10444 }
10446 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10450 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10451 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10452 (-ARG1 + ARG0) reduces to -ARG1. */
10456 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10457 __complex__ ( x, -y ). This is not the same for SNaNs or if
10458 signed zeros are involved. */
10462 {
10469 {
10473 {
10475 arg1r ? arg1r
10480 }
10482 {
10486 arg1i ? arg1i
10489 }
10490 }
10491 }
10493 /* Fold &x - &x. This can happen from &x.foo - &x.
10494 This is unsafe for certain floats even in non-IEEE formats.
10495 In IEEE, it is unsafe because it does wrong for NaNs.
10496 Also note that operand_equal_p is always false if an operand
10497 is volatile. */
10503 /* A - B -> A + (-B) if B is easily negatable. */
10506 /* Avoid this transformation if B is a positive REAL_CST. */
10514 /* Try folding difference of addresses. */
10515 {
10516 HOST_WIDE_INT diff;
10522 }
10524 /* Fold &a[i] - &a[j] to i-j. */
10529 {
10534 {
10542 }
10543 }
10546 && flag_unsafe_math_optimizations
10552 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10553 same or one. Make sure type is not saturating.
10554 fold_plusminus_mult_expr will re-associate. */
10559 {
10563 }
10568 /* (-A) * (-B) -> A * B */
10579 {
10584 /* Transform x * -1 into -x. Make sure to do the negation
10585 on the original operand with conversions not stripped
10586 because we can only strip non-sign-changing conversions. */
10589 /* Transform x * -C into -x * C if x is easily negatable. */
10598 /* (a * (1 << b)) is (a << b) */
10608 /* (A + A) * C -> A * 2 * C */
10623 {
10626 "occur when simplifying "
10628 WARN_STRICT_OVERFLOW_MISC);
10630 }
10632 /* Optimize z * conj(z) for integer complex numbers. */
10639 }
10640 else
10641 {
10642 /* Maybe fold x * 0 to 0. The expressions aren't the same
10643 when x is NaN, since x * 0 is also NaN. Nor are they the
10644 same in modes with signed zeros, since multiplying a
10645 negative value by 0 gives -0, not +0. */
10650 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10655 /* Transform x * -1.0 into -x. */
10660 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10661 the result for floating point types due to rounding so it is applied
10662 only if -fassociative-math was specify. */
10667 {
10673 }
10675 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10677 {
10680 {
10683 }
10684 }
10686 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10687 This is not the same for NaNs or if signed zeros are
10688 involved. */
10694 {
10706 }
10708 /* Optimize z * conj(z) for floating point complex numbers.
10709 Guarded by flag_unsafe_math_optimizations as non-finite
10710 imaginary components don't produce scalar results. */
10721 {
10725 /* Optimizations of root(...)*root(...). */
10727 {
10732 /* Optimize sqrt(x)*sqrt(x) as x. */
10738 /* Optimize root(x)*root(y) as root(x*y). */
10742 }
10744 /* Optimize expN(x)*expN(y) as expN(x+y). */
10746 {
10752 }
10754 /* Optimizations of pow(...)*pow(...). */
10758 {
10764 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10766 {
10770 }
10772 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10774 {
10778 }
10779 }
10781 /* Optimize tan(x)*cos(x) as sin(x). */
10790 {
10795 }
10797 /* Optimize x*pow(x,c) as pow(x,c+1). */
10801 {
10807 {
10809 REAL_VALUE_TYPE c;
10810 tree arg;
10816 }
10817 }
10819 /* Optimize pow(x,c)*x as pow(x,c+1). */
10823 {
10829 {
10831 REAL_VALUE_TYPE c;
10832 tree arg;
10838 }
10839 }
10841 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10844 {
10848 {
10851 }
10852 }
10853 }
10854 }
10858 bit_ior:
10866 /* ~X | X is -1. */
10869 {
10873 }
10875 /* X | ~X is -1. */
10878 {
10882 }
10884 /* Canonicalize (X & C1) | C2. */
10888 {
10896 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10901 {
10905 }
10906 else
10907 {
10911 }
10913 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10918 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10919 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10920 mode which allows further optimizations. */
10930 {
10931 unsigned HOST_WIDE_INT mask
10935 {
10939 }
10940 }
10947 arg1);
10948 }
10950 /* (X & Y) | Y is (X, Y). */
10954 /* (X & Y) | X is (Y, X). */
10959 /* X | (X & Y) is (Y, X). */
10964 /* X | (Y & X) is (Y, X). */
10974 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10976 This results in more efficient code for machines without a NAND
10977 instruction. Combine will canonicalize to the first form
10978 which will allow use of NAND instructions provided by the
10979 backend if they exist. */
10982 {
10989 }
10991 /* See if this can be simplified into a rotate first. If that
10992 is unsuccessful continue in the association code. */
11003 /* ~X ^ X is -1. */
11006 {
11010 }
11012 /* X ^ ~X is -1. */
11015 {
11019 }
11021 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11022 with a constant, and the two constants have no bits in common,
11023 we should treat this as a BIT_IOR_EXPR since this may produce more
11024 simplifications. */
11032 {
11035 }
11037 /* (X | Y) ^ X -> Y & ~ X*/
11040 {
11043 arg1);
11047 }
11049 /* (Y | X) ^ X -> Y & ~ X*/
11052 {
11055 arg1);
11059 }
11061 /* X ^ (X | Y) -> Y & ~ X*/
11064 {
11067 arg0);
11071 }
11073 /* X ^ (Y | X) -> Y & ~ X*/
11076 {
11079 arg0);
11083 }
11085 /* Convert ~X ^ ~Y to X ^ Y. */
11092 /* Convert ~X ^ C to X ^ ~C. */
11099 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11106 /* Fold (X & Y) ^ Y as ~X & Y. */
11109 {
11114 }
11115 /* Fold (X & Y) ^ X as ~Y & X. */
11119 {
11124 }
11125 /* Fold X ^ (X & Y) as X & ~Y. */
11128 {
11133 }
11134 /* Fold X ^ (Y & X) as ~Y & X. */
11138 {
11143 }
11145 /* See if this can be simplified into a rotate first. If that
11146 is unsuccessful continue in the association code. */
11157 /* ~X & X is always zero. */
11162 /* X & ~X is always zero. */
11167 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11171 {
11179 }
11181 /* (X | Y) & Y is (X, Y). */
11185 /* (X | Y) & X is (Y, X). */
11190 /* X & (X | Y) is (Y, X). */
11195 /* X & (Y | X) is (Y, X). */
11201 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11205 {
11211 }
11212 /* Fold ~X & 1 as (X & 1) == 0. */
11215 {
11221 }
11223 /* Fold (X ^ Y) & Y as ~X & Y. */
11226 {
11231 }
11232 /* Fold (X ^ Y) & X as ~Y & X. */
11236 {
11241 }
11242 /* Fold X & (X ^ Y) as X & ~Y. */
11245 {
11250 }
11251 /* Fold X & (Y ^ X) as ~Y & X. */
11255 {
11260 }
11265 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11268 {
11269 unsigned int prec
11276 }
11278 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11280 This results in more efficient code for machines without a NOR
11281 instruction. Combine will canonicalize to the first form
11282 which will allow use of NOR instructions provided by the
11283 backend if they exist. */
11286 {
11293 }
11295 /* If arg0 is derived from the address of an object or function, we may
11296 be able to fold this expression using the object or function's
11297 alignment. */
11299 {
11306 /* This works because modulus is a power of 2. If this weren't the
11307 case, we'd have to replace it by its greatest power-of-2
11308 divisor: modulus & -modulus. */
11311 }
11313 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11314 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11315 if the new mask might be further optimized. */
11324 {
11326 unsigned HOST_WIDE_INT mask
11336 {
11339 /* See if more bits can be proven as zero because of
11340 zero extension. */
11343 {
11348 {
11350 /* See if we can shorten the right shift. */
11353 }
11354 }
11358 /* For arithmetic shift if sign bit could be set, zerobits
11359 can contain actually sign bits, so no transformation is
11360 possible, unless MASK masks them all away. In that
11361 case the shift needs to be converted into logical shift. */
11364 {
11367 else
11369 }
11370 }
11372 /* ((X << 16) & 0xff00) is (X, 0). */
11378 {
11381 /* Only do the transformation if NEWMASK is some integer
11382 mode's mask. */
11389 {
11391 {
11397 }
11398 else
11402 newmask));
11403 }
11404 }
11405 }
11410 /* Don't touch a floating-point divide by zero unless the mode
11411 of the constant can represent infinity. */
11417 /* Optimize A / A to 1.0 if we don't care about
11418 NaNs or Infinities. Skip the transformation
11419 for non-real operands. */
11424 {
11428 }
11430 /* The complex version of the above A / A optimization. */
11433 {
11437 {
11439 /* omit_two_operands will call fold_convert for us. */
11441 }
11442 }
11444 /* (-A) / (-B) -> A / B */
11454 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11459 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11464 /* If ARG1 is a constant, we can convert this to a multiply by the
11465 reciprocal. This does not have the same rounding properties,
11466 so only do this if -freciprocal-math. We can actually
11467 always safely do it if ARG1 is a power of two, but it's hard to
11468 tell if it is or not in a portable manner. */
11470 {
11475 /* Find the reciprocal if optimizing and the result is exact. */
11477 {
11478 REAL_VALUE_TYPE r;
11481 {
11485 }
11486 }
11487 }
11488 /* Convert A/B/C to A/(B*C). */
11495 /* Convert A/(B/C) to (A/B)*C. */
11503 /* Convert C1/(X*C2) into (C1/C2)/X. */
11508 {
11514 }
11517 {
11521 /* Optimize sin(x)/cos(x) as tan(x). */
11527 {
11532 }
11534 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11540 {
11544 {
11548 }
11549 }
11551 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11552 NaNs or Infinities. */
11556 {
11563 {
11568 }
11569 }
11571 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11572 NaNs or Infinities. */
11576 {
11583 {
11587 {
11591 tmp);
11592 }
11593 }
11594 }
11596 /* Optimize pow(x,c)/x as pow(x,c-1). */
11600 {
11606 {
11608 REAL_VALUE_TYPE c;
11609 tree arg;
11615 }
11616 }
11618 /* Optimize a/root(b/c) into a*root(c/b). */
11620 {
11624 {
11633 }
11634 }
11636 /* Optimize x/expN(y) into x*expN(-y). */
11638 {
11643 }
11645 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11649 {
11656 }
11657 }
11662 /* Simplify A / (B << N) where A and B are positive and B is
11663 a power of 2, to A >> (N + log2(B)). */
11668 {
11671 {
11678 WARN_STRICT_OVERFLOW_MISC);
11684 }
11685 }
11687 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11688 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11694 /* Fall thru */
11703 /* X / -1 is -X. */
11710 /* Convert -A / -B to A / B when the type is signed and overflow is
11711 undefined. */
11715 {
11718 "when distributing negation across "
11720 WARN_STRICT_OVERFLOW_MISC);
11724 }
11728 {
11731 "when distributing negation across "
11733 WARN_STRICT_OVERFLOW_MISC);
11737 }
11739 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11740 operation, EXACT_DIV_EXPR.
11742 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11743 At one time others generated faster code, it's not clear if they do
11744 after the last round to changes to the DIV code in expmed.c. */
11753 {
11757 WARN_STRICT_OVERFLOW_MISC);
11759 }
11767 /* X % 1 is always zero, but be sure to preserve any side
11768 effects in X. */
11772 /* X % 0, return X % 0 unchanged so that we can get the
11773 proper warnings and errors. */
11777 /* 0 % X is always zero, but be sure to preserve any side
11778 effects in X. Place this after checking for X == 0. */
11782 /* X % -1 is zero. */
11789 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11790 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11795 {
11797 /* Also optimize A % (C << N) where C is a power of 2,
11798 to A & ((C << N) - 1). */
11803 {
11808 "occur when simplifying "
11810 WARN_STRICT_OVERFLOW_MISC);
11814 }
11815 }
11817 /* X % -C is the same as X % C. */
11824 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11829 /* X % -Y is the same as X % Y. */
11840 {
11844 WARN_STRICT_OVERFLOW_MISC);
11846 }
11857 /* Optimize -1 >> x for arithmetic right shifts. */
11861 /* ... fall through ... */
11864 shift:
11870 /* Since negative shift count is not well-defined,
11871 don't try to compute it in the compiler. */
11875 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11880 {
11884 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11885 being well defined. */
11887 {
11893 else
11895 }
11899 }
11901 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11902 into x & ((unsigned)-1 >> c) for unsigned types. */
11910 {
11913 tree lshift;
11914 tree arg00;
11917 {
11924 }
11925 }
11927 /* Rewrite an LROTATE_EXPR by a constant into an
11928 RROTATE_EXPR by a new constant. */
11930 {
11935 }
11937 /* If we have a rotate of a bit operation with the rotate count and
11938 the second operand of the bit operation both constant,
11939 permute the two operations. */
11951 /* Two consecutive rotates adding up to the precision of the
11952 type can be ignored. */
11963 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11964 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11965 if the latter can be further optimized. */
11970 {
11973 arg1);
11976 arg1);
11980 }
12008 /* Note that the operands of this must be ints
12009 and their values must be 0 or 1.
12010 ("true" is a fixed value perhaps depending on the language.) */
12011 /* If first arg is constant zero, return it. */
12015 /* If either arg is constant true, drop it. */
12019 /* Preserve sequence points. */
12022 /* If second arg is constant zero, result is zero, but first arg
12023 must be evaluated. */
12026 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12027 case will be handled here. */
12031 /* !X && X is always false. */
12035 /* X && !X is always false. */
12040 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12041 means A >= Y && A != MAX, but in this case we know that
12042 A < X <= MAX. */
12046 {
12054 }
12056 truth_andor:
12057 /* We only do these simplifications if we are optimizing. */
12061 /* Check for things like (A || B) && (A || C). We can convert this
12062 to A || (B && C). Note that either operator can be any of the four
12063 truth and/or operations and the transformation will still be
12064 valid. Also note that we only care about order for the
12065 ANDIF and ORIF operators. If B contains side effects, this
12066 might change the truth-value of A. */
12073 {
12093 /* This case if tricky because we must either have commutative
12094 operators or else A10 must not have side-effects. */
12100 a01);
12101 }
12103 /* See if we can build a range comparison. */
12107 /* Check for the possibility of merging component references. If our
12108 lhs is another similar operation, try to merge its rhs with our
12109 rhs. Then try to merge our lhs and rhs. */
12121 /* Note that the operands of this must be ints
12122 and their values must be 0 or true.
12123 ("true" is a fixed value perhaps depending on the language.) */
12124 /* If first arg is constant true, return it. */
12128 /* If either arg is constant zero, drop it. */
12132 /* Preserve sequence points. */
12135 /* If second arg is constant true, result is true, but we must
12136 evaluate first arg. */
12139 /* Likewise for first arg, but note this only occurs here for
12140 TRUTH_OR_EXPR. */
12144 /* !X || X is always true. */
12148 /* X || !X is always true. */
12156 /* If the second arg is constant zero, drop it. */
12159 /* If the second arg is constant true, this is a logical inversion. */
12161 {
12162 /* Only call invert_truthvalue if operand is a truth value. */
12165 else
12168 }
12169 /* Identical arguments cancel to zero. */
12173 /* !X ^ X is always true. */
12178 /* X ^ !X is always true. */
12191 /* bool_var != 0 becomes bool_var. */
12196 /* bool_var == 1 becomes bool_var. */
12201 /* bool_var != 1 becomes !bool_var. */
12206 /* bool_var == 0 becomes !bool_var. */
12211 /* If this is an equality comparison of the address of two non-weak,
12212 unaliased symbols neither of which are extern (since we do not
12213 have access to attributes for externs), then we know the result. */
12226 {
12227 /* We know that we're looking at the address of two
12228 non-weak, unaliased, static _DECL nodes.
12230 It is both wasteful and incorrect to call operand_equal_p
12231 to compare the two ADDR_EXPR nodes. It is wasteful in that
12232 all we need to do is test pointer equality for the arguments
12233 to the two ADDR_EXPR nodes. It is incorrect to use
12234 operand_equal_p as that function is NOT equivalent to a
12235 C equality test. It can in fact return false for two
12236 objects which would test as equal using the C equality
12237 operator. */
12241 type);
12242 }
12244 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12245 a MINUS_EXPR of a constant, we can convert it into a comparison with
12246 a revised constant as long as no overflow occurs. */
12258 /* Similarly for a NEGATE_EXPR. */
12266 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12275 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12282 {
12286 val,
12290 }
12292 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12297 {
12299 code == NE_EXPR
12302 }
12304 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12305 for !=. Don't do this for ordered comparisons due to overflow. */
12311 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12316 /* If this is an EQ or NE comparison with zero and ARG0 is
12317 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12318 two operations, but the latter can be done in one less insn
12319 on machines that have only two-operand insns or on which a
12320 constant cannot be the first operand. */
12323 {
12328 {
12335 }
12338 {
12345 }
12346 }
12348 /* If this is an NE or EQ comparison of zero against the result of a
12349 signed MOD operation whose second operand is a power of 2, make
12350 the MOD operation unsigned since it is simpler and equivalent. */
12358 {
12368 }
12370 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12371 C1 is a valid shift constant, and C2 is a power of two, i.e.
12372 a single bit. */
12376 == INTEGER_CST
12379 {
12384 /* Check for a valid shift count. */
12387 {
12391 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12392 can be rewritten as (X & (C2 << C1)) != 0. */
12394 {
12398 }
12399 /* Otherwise, for signed (arithmetic) shifts,
12400 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12401 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12405 /* Otherwise, of unsigned (logical) shifts,
12406 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12407 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12408 else
12412 arg000);
12413 }
12414 }
12416 /* If this is an NE comparison of zero with an AND of one, remove the
12417 comparison since the AND will give the correct value. */
12424 /* If we have (A & C) == C where C is a power of 2, convert this into
12425 (A & C) != 0. Similarly for NE_EXPR. */
12431 integer_zero_node));
12433 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12434 bit, then fold the expression into A < 0 or A >= 0. */
12439 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12440 Similarly for NE_EXPR. */
12444 {
12453 }
12455 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12456 Similarly for NE_EXPR. */
12460 {
12467 }
12469 /* If this is a comparison of a field, we may be able to simplify it. */
12472 /* Handle the constant case even without -O
12473 to make sure the warnings are given. */
12475 {
12479 }
12481 /* Optimize comparisons of strlen vs zero to a compare of the
12482 first character of the string vs zero. To wit,
12483 strlen(ptr) == 0 => *ptr == 0
12484 strlen(ptr) != 0 => *ptr != 0
12485 Other cases should reduce to one of these two (or a constant)
12486 due to the return value of strlen being unsigned. */
12489 {
12497 {
12501 }
12502 }
12504 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12505 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12509 {
12516 {
12518 {
12521 }
12524 }
12525 }
12527 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12533 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12538 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12545 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12553 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12554 (X & C) == 0 when C is a single bit. */
12559 {
12565 }
12567 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12568 constant C is a power of two, i.e. a single bit. */
12575 {
12579 }
12581 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12582 when is C is a power of two, i.e. a single bit. */
12589 {
12595 }
12599 {
12602 }
12604 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12611 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12614 {
12626 arg01),
12634 arg01),
12642 arg00),
12650 arg00),
12652 }
12656 {
12663 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12664 operand_equal_p guarantees no side-effects so we don't need
12665 to use omit_one_operand on Z. */
12675 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12682 arg10);
12683 }
12685 /* Attempt to simplify equality/inequality comparisons of complex
12686 values. Only lower the comparison if the result is known or
12687 can be simplified to a single scalar comparison. */
12692 {
12697 {
12700 }
12701 else
12702 {
12705 }
12708 {
12711 }
12712 else
12713 {
12716 }
12720 {
12722 {
12727 }
12728 else
12729 {
12734 }
12735 }
12739 {
12741 {
12746 }
12747 else
12748 {
12753 }
12754 }
12755 }
12767 /* Transform comparisons of the form X +- C CMP X. */
12774 {
12781 else
12784 /* (X - c) > X becomes false. */
12788 {
12792 "occur when assuming that (X - c) > X "
12794 WARN_STRICT_OVERFLOW_ALL);
12796 }
12798 /* Likewise (X + c) < X becomes false. */
12802 {
12806 "occur when assuming that "
12808 WARN_STRICT_OVERFLOW_ALL);
12810 }
12812 /* Convert (X - c) <= X to true. */
12817 {
12821 "occur when assuming that "
12823 WARN_STRICT_OVERFLOW_ALL);
12825 }
12827 /* Convert (X + c) >= X to true. */
12832 {
12836 "occur when assuming that "
12838 WARN_STRICT_OVERFLOW_ALL);
12840 }
12843 {
12844 /* Convert X + c > X and X - c < X to true for integers. */
12848 {
12851 "not occur when assuming that "
12853 WARN_STRICT_OVERFLOW_ALL);
12855 }
12860 {
12863 "not occur when assuming that "
12865 WARN_STRICT_OVERFLOW_ALL);
12867 }
12869 /* Convert X + c <= X and X - c >= X to false for integers. */
12873 {
12876 "not occur when assuming that "
12878 WARN_STRICT_OVERFLOW_ALL);
12880 }
12885 {
12888 "not occur when assuming that "
12890 WARN_STRICT_OVERFLOW_ALL);
12892 }
12893 }
12894 }
12896 /* Comparisons with the highest or lowest possible integer of
12897 the specified precision will have known values. */
12898 {
12905 {
12906 HOST_WIDE_INT signed_max_hi;
12911 {
12918 {
12922 }
12923 else
12924 {
12928 }
12929 }
12930 else
12931 {
12940 {
12943 }
12944 else
12945 {
12948 }
12949 }
12954 {
12967 /* The GE_EXPR and LT_EXPR cases above are not normally
12968 reached because of previous transformations. */
12972 }
12974 == max_hi
12977 {
12983 arg1);
12989 arg1);
12992 }
12994 == min_hi
12997 {
13012 }
13014 == min_hi
13017 {
13022 arg1);
13027 arg1);
13030 }
13035 /* We will flip the signedness of the comparison operator
13036 associated with the mode of arg1, so the sign bit is
13037 specified by this mode. Check that arg1 is the signed
13038 max associated with this sign bit. */
13040 /* signed_type does not work on pointer types. */
13042 {
13043 /* The following case also applies to X < signed_max+1
13044 and X >= signed_max+1 because previous transformations. */
13046 {
13047 tree st;
13052 }
13053 }
13054 }
13055 }
13057 /* If we are comparing an ABS_EXPR with a constant, we can
13058 convert all the cases into explicit comparisons, but they may
13059 well not be faster than doing the ABS and one comparison.
13060 But ABS (X) <= C is a range comparison, which becomes a subtraction
13061 and a comparison, and is probably faster. */
13075 /* Convert ABS_EXPR<x> >= 0 to true. */
13082 {
13085 "when simplifying comparison of "
13087 WARN_STRICT_OVERFLOW_CONDITIONAL);
13089 }
13091 /* Convert ABS_EXPR<x> < 0 to false. */
13096 {
13099 "when simplifying comparison of "
13101 WARN_STRICT_OVERFLOW_CONDITIONAL);
13103 }
13105 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13106 and similarly for >= into !=. */
13121 return
13140 {
13144 }
13146 /* If the first operand is NaN, the result is constant. */
13150 {
13152 ? integer_zero_node
13155 }
13157 /* If the second operand is NaN, the result is constant. */
13161 {
13163 ? integer_zero_node
13166 }
13168 /* Simplify unordered comparison of something with itself. */
13174 && !flag_trapping_math
13178 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13179 {
13190 }
13195 /* When pedantic, a compound expression can be neither an lvalue
13196 nor an integer constant expression. */
13199 /* Don't let (0, 0) be null pointer constant. */
13213 /* An ASSERT_EXPR should never be passed to fold_binary. */
13219 }
13221 /* Callback for walk_tree, looking for LABEL_EXPR.
13222 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13223 Do not check the sub-tree of GOTO_EXPR. */
13225 static tree
13229 {
13231 {
13236 /* no break */
13239 }
13240 }
13242 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13243 accessible from outside the sub-tree. Returns NULL_TREE if no
13244 addressable label is found. */
13246 static bool
13248 {
13250 }
13252 /* Fold a ternary expression of code CODE and type TYPE with operands
13253 OP0, OP1, and OP2. Return the folded expression if folding is
13254 successful. Otherwise, return NULL_TREE. */
13256 tree
13258 {
13259 tree tem;
13266 /* Strip any conversions that don't change the mode. This is safe
13267 for every expression, except for a comparison expression because
13268 its signedness is derived from its operands. So, in the latter
13269 case, only strip conversions that don't change the signedness.
13271 Note that this is done as an internal manipulation within the
13272 constant folder, in order to find the simplest representation of
13273 the arguments so that their form can be studied. In any cases,
13274 the appropriate type conversions should be put back in the tree
13275 that will get out of the constant folder. */
13277 {
13280 }
13283 {
13286 }
13289 {
13293 {
13299 }
13303 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13304 so all simple results must be passed through pedantic_non_lvalue. */
13306 {
13309 /* Only optimize constant conditions when the selected branch
13310 has the same type as the COND_EXPR. This avoids optimizing
13311 away "c ? x : throw", where the throw has a void type.
13312 Avoid throwing away that operand which contains label. */
13319 }
13323 /* If we have A op B ? A : C, we may be able to convert this to a
13324 simpler expression, depending on the operation and the values
13325 of B and C. Signed zeros prevent all of these transformations,
13326 for reasons given above each one.
13328 Also try swapping the arguments and inverting the conditional. */
13333 {
13337 }
13341 op2,
13344 {
13347 {
13351 }
13352 }
13354 /* If the second operand is simpler than the third, swap them
13355 since that produces better jump optimization results. */
13358 {
13359 /* See if this can be inverted. If it can't, possibly because
13360 it was a floating-point inequality comparison, don't do
13361 anything. */
13365 }
13367 /* Convert A ? 1 : 0 to simply A. */
13370 /* If we try to convert OP0 to our type, the
13371 call to fold will try to move the conversion inside
13372 a COND, which will recurse. In that case, the COND_EXPR
13373 is probably the best choice, so leave it alone. */
13377 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13378 over COND_EXPR in cases such as floating point comparisons. */
13385 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13390 {
13391 /* sign_bit_p only checks ARG1 bits within A's precision.
13392 If <sign bit of A> has wider type than A, bits outside
13393 of A's precision in <sign bit of A> need to be checked.
13394 If they are all 0, this optimization needs to be done
13395 in unsigned A's type, if they are all 1 in signed A's type,
13396 otherwise this can't be done. */
13401 {
13403 HOST_WIDE_INT mask_hi;
13405 tree tem_type;
13413 {
13417 }
13418 else
13419 {
13423 }
13425 {
13429 }
13430 else
13436 {
13439 }
13442 {
13445 }
13446 else
13448 }
13455 arg1)));
13456 }
13458 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13459 already handled above. */
13464 {
13473 }
13475 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13476 is probably obsolete because the first operand should be a
13477 truth value (that's why we have the two cases above), but let's
13478 leave it in until we can confirm this for all front-ends. */
13489 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13495 arg1);
13497 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13501 {
13502 /* Only perform transformation if ARG0 is easily inverted. */
13507 arg1);
13508 }
13510 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13514 {
13515 /* Only perform transformation if ARG0 is easily inverted. */
13520 op2);
13521 }
13523 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13529 op2);
13534 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13535 of fold_ternary on them. */
13542 {
13551 {
13556 else
13557 {
13559 tree value;
13563 }
13568 else
13570 }
13571 }
13573 /* A bit-field-ref that referenced the full argument can be stripped. */
13584 }
13586 /* Perform constant folding and related simplification of EXPR.
13587 The related simplifications include x*1 => x, x*0 => 0, etc.,
13588 and application of the associative law.
13589 NOP_EXPR conversions may be removed freely (as long as we
13590 are careful not to change the type of the overall expression).
13591 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13592 but we can constant-fold them if they have constant operands. */
13594 #ifdef ENABLE_FOLD_CHECKING
13595 # define fold(x) fold_1 (x)
13597 static
13598 #endif
13599 tree
13601 {
13605 tree tem;
13607 /* Return right away if a constant. */
13611 /* CALL_EXPR-like objects with variable numbers of operands are
13612 treated specially. */
13614 {
13616 {
13619 }
13621 }
13624 {
13629 {
13647 }
13648 }
13651 {
13653 {
13660 {
13665 /* Find a matching index by means of a binary search. */
13667 {
13683 else
13685 }
13686 }
13689 }
13697 }
13699 #ifdef ENABLE_FOLD_CHECKING
13700 #undef fold
13706 /* When --enable-checking=fold, compute a digest of expr before
13707 and after actual fold call to see if fold did not accidentally
13708 change original expr. */
13710 tree
13712 {
13713 tree ret;
13716 htab_t ht;
13735 }
13737 void
13739 {
13742 htab_t ht;
13752 }
13754 static void
13756 {
13758 }
13760 static void
13762 {
13768 recursive_label:
13782 {
13783 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13787 }
13794 {
13795 /* Allow these fields to be modified. */
13796 tree tmp;
13804 {
13807 }
13808 }
13817 {
13820 {
13834 }
13838 {
13851 }
13868 {
13874 }
13879 {
13883 }
13894 {
13897 }
13907 }
13908 }
13910 /* Helper function for outputting the checksum of a tree T. When
13911 debugging with gdb, you can "define mynext" to be "next" followed
13912 by "call debug_fold_checksum (op0)", then just trace down till the
13913 outputs differ. */
13915 void
13917 {
13932 }
13934 #endif
13936 /* Fold a unary tree expression with code CODE of type TYPE with an
13937 operand OP0. Return a folded expression if successful. Otherwise,
13938 return a tree expression with code CODE of type TYPE with an
13939 operand OP0. */
13941 tree
13943 {
13944 tree tem;
13945 #ifdef ENABLE_FOLD_CHECKING
13948 htab_t ht;
13955 #endif
13961 #ifdef ENABLE_FOLD_CHECKING
13969 #endif
13971 }
13973 /* Fold a binary tree expression with code CODE of type TYPE with
13974 operands OP0 and OP1. Return a folded expression if successful.
13975 Otherwise, return a tree expression with code CODE of type TYPE
13976 with operands OP0 and OP1. */
13978 tree
13980 MEM_STAT_DECL)
13981 {
13982 tree tem;
13983 #ifdef ENABLE_FOLD_CHECKING
13989 htab_t ht;
14001 #endif
14007 #ifdef ENABLE_FOLD_CHECKING
14023 #endif
14025 }
14027 /* Fold a ternary tree expression with code CODE of type TYPE with
14028 operands OP0, OP1, and OP2. Return a folded expression if
14029 successful. Otherwise, return a tree expression with code CODE of
14030 type TYPE with operands OP0, OP1, and OP2. */
14032 tree
14034 MEM_STAT_DECL)
14035 {
14036 tree tem;
14037 #ifdef ENABLE_FOLD_CHECKING
14045 htab_t ht;
14062 #endif
14069 #ifdef ENABLE_FOLD_CHECKING
14093 #endif
14095 }
14097 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14098 arguments in ARGARRAY, and a null static chain.
14099 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14100 of type TYPE from the given operands as constructed by build_call_array. */
14102 tree
14104 {
14105 tree tem;
14106 #ifdef ENABLE_FOLD_CHECKING
14112 htab_t ht;
14126 #endif
14130 #ifdef ENABLE_FOLD_CHECKING
14147 #endif
14149 }
14151 /* Perform constant folding and related simplification of initializer
14152 expression EXPR. These behave identically to "fold_buildN" but ignore
14153 potential run-time traps and exceptions that fold must preserve. */
14155 #define START_FOLD_INIT \
14156 int saved_signaling_nans = flag_signaling_nans;\
14157 int saved_trapping_math = flag_trapping_math;\
14158 int saved_rounding_math = flag_rounding_math;\
14159 int saved_trapv = flag_trapv;\
14160 int saved_folding_initializer = folding_initializer;\
14161 flag_signaling_nans = 0;\
14162 flag_trapping_math = 0;\
14163 flag_rounding_math = 0;\
14164 flag_trapv = 0;\
14165 folding_initializer = 1;
14167 #define END_FOLD_INIT \
14168 flag_signaling_nans = saved_signaling_nans;\
14169 flag_trapping_math = saved_trapping_math;\
14170 flag_rounding_math = saved_rounding_math;\
14171 flag_trapv = saved_trapv;\
14172 folding_initializer = saved_folding_initializer;
14174 tree
14176 {
14177 tree result;
14178 START_FOLD_INIT;
14182 END_FOLD_INIT;
14184 }
14186 tree
14188 {
14189 tree result;
14190 START_FOLD_INIT;
14194 END_FOLD_INIT;
14196 }
14198 tree
14200 tree op2)
14201 {
14202 tree result;
14203 START_FOLD_INIT;
14207 END_FOLD_INIT;
14209 }
14211 tree
14214 {
14215 tree result;
14216 START_FOLD_INIT;
14220 END_FOLD_INIT;
14222 }
14224 #undef START_FOLD_INIT
14225 #undef END_FOLD_INIT
14227 /* Determine if first argument is a multiple of second argument. Return 0 if
14228 it is not, or we cannot easily determined it to be.
14230 An example of the sort of thing we care about (at this point; this routine
14231 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14232 fold cases do now) is discovering that
14234 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14236 is a multiple of
14238 SAVE_EXPR (J * 8)
14240 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14242 This code also handles discovering that
14244 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14246 is a multiple of 8 so we don't have to worry about dealing with a
14247 possible remainder.
14249 Note that we *look* inside a SAVE_EXPR only to determine how it was
14250 calculated; it is not safe for fold to do much of anything else with the
14251 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14252 at run time. For example, the latter example above *cannot* be implemented
14253 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14254 evaluation time of the original SAVE_EXPR is not necessarily the same at
14255 the time the new expression is evaluated. The only optimization of this
14256 sort that would be valid is changing
14258 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14260 divided by 8 to
14262 SAVE_EXPR (I) * SAVE_EXPR (J)
14264 (where the same SAVE_EXPR (J) is used in the original and the
14265 transformed version). */
14267 int
14269 {
14277 {
14279 /* Bitwise and provides a power of two multiple. If the mask is
14280 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14283 /* FALLTHRU */
14296 {
14300 /* const_binop may not detect overflow correctly,
14301 so check for it explicitly here. */
14307 size_one_node,
14311 }
14315 /* Can't handle conversions from non-integral or wider integral type. */
14321 /* .. fall through ... */
14338 }
14339 }
14341 /* Return true if CODE or TYPE is known to be non-negative. */
14343 static bool
14345 {
14348 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14349 have a signed:1 type (where the value is -1 and 0). */
14352 }
14354 /* Return true if (CODE OP0) is known to be non-negative. If the return
14355 value is based on the assumption that signed overflow is undefined,
14356 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14357 *STRICT_OVERFLOW_P. */
14359 bool
14362 {
14367 {
14369 /* We can't return 1 if flag_wrapv is set because
14370 ABS_EXPR<INT_MIN> = INT_MIN. */
14374 {
14377 }
14384 strict_overflow_p);
14387 {
14392 {
14395 strict_overflow_p);
14397 {
14401 strict_overflow_p);
14402 }
14403 }
14405 {
14408 strict_overflow_p);
14412 }
14413 }
14418 }
14420 /* We don't know sign of `t', so be conservative and return false. */
14422 }
14424 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14425 value is based on the assumption that signed overflow is undefined,
14426 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14427 *STRICT_OVERFLOW_P. */
14429 bool
14432 {
14437 {
14442 strict_overflow_p)
14444 strict_overflow_p));
14446 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14447 both unsigned and at least 2 bits shorter than the result. */
14451 {
14456 {
14460 }
14461 }
14466 {
14467 /* x * x for floating point x is always non-negative. */
14471 strict_overflow_p)
14473 strict_overflow_p));
14474 }
14476 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14477 both unsigned and their total bits is shorter than the result. */
14481 {
14500 {
14510 }
14511 }
14517 strict_overflow_p)
14519 strict_overflow_p));
14530 strict_overflow_p)
14532 strict_overflow_p));
14539 strict_overflow_p);
14542 }
14544 /* We don't know sign of `t', so be conservative and return false. */
14546 }
14548 /* Return true if T is known to be non-negative. If the return
14549 value is based on the assumption that signed overflow is undefined,
14550 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14551 *STRICT_OVERFLOW_P. */
14553 bool
14555 {
14560 {
14572 strict_overflow_p)
14574 strict_overflow_p));
14578 }
14579 /* We don't know sign of `t', so be conservative and return false. */
14581 }
14583 /* Return true if T is known to be non-negative. If the return
14584 value is based on the assumption that signed overflow is undefined,
14585 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14586 *STRICT_OVERFLOW_P. */
14588 bool
14591 {
14594 {
14612 /* Always true. */
14616 /* sqrt(-0.0) is -0.0. */
14620 strict_overflow_p);
14653 /* True if the 1st argument is nonnegative. */
14655 strict_overflow_p);
14658 /* True if the 1st OR 2nd arguments are nonnegative. */
14660 strict_overflow_p)
14662 strict_overflow_p)));
14665 /* True if the 1st AND 2nd arguments are nonnegative. */
14667 strict_overflow_p)
14669 strict_overflow_p)));
14672 /* True if the 2nd argument is nonnegative. */
14674 strict_overflow_p);
14677 /* True if the 1st argument is nonnegative or the second
14678 argument is an even integer. */
14683 strict_overflow_p);
14686 /* True if the 1st argument is nonnegative or the second
14687 argument is an even integer valued real. */
14689 {
14690 REAL_VALUE_TYPE c;
14691 HOST_WIDE_INT n;
14696 {
14697 REAL_VALUE_TYPE cint;
14702 }
14703 }
14705 strict_overflow_p);
14709 }
14711 type);
14712 }
14714 /* Return true if T is known to be non-negative. If the return
14715 value is based on the assumption that signed overflow is undefined,
14716 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14717 *STRICT_OVERFLOW_P. */
14719 bool
14721 {
14727 {
14729 {
14733 /* If the initializer is non-void, then it's a normal expression
14734 that will be assigned to the slot. */
14738 /* Otherwise, the initializer sets the slot in some way. One common
14739 way is an assignment statement at the end of the initializer. */
14741 {
14749 else
14751 }
14755 strict_overflow_p);
14758 }
14761 {
14767 arg0,
14768 arg1,
14769 strict_overflow_p);
14770 }
14774 strict_overflow_p);
14777 strict_overflow_p);
14780 strict_overflow_p);
14785 }
14787 /* We don't know sign of `t', so be conservative and return false. */
14789 }
14791 /* Return true if T is known to be non-negative. If the return
14792 value is based on the assumption that signed overflow is undefined,
14793 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14794 *STRICT_OVERFLOW_P. */
14796 bool
14798 {
14805 {
14812 strict_overflow_p);
14818 strict_overflow_p);
14827 }
14830 {
14838 strict_overflow_p);
14843 strict_overflow_p);
14858 }
14859 }
14861 /* Return true if `t' is known to be non-negative. Handle warnings
14862 about undefined signed overflow. */
14864 bool
14866 {
14873 "determining that expression is always "
14875 WARN_STRICT_OVERFLOW_MISC);
14877 }
14880 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14881 For floating point we further ensure that T is not denormal.
14882 Similar logic is present in nonzero_address in rtlanal.h.
14884 If the return value is based on the assumption that signed overflow
14885 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14886 change *STRICT_OVERFLOW_P. */
14888 bool
14891 {
14893 {
14896 strict_overflow_p);
14899 {
14905 strict_overflow_p));
14906 }
14911 strict_overflow_p);
14915 }
14918 }
14920 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14921 For floating point we further ensure that T is not denormal.
14922 Similar logic is present in nonzero_address in rtlanal.h.
14924 If the return value is based on the assumption that signed overflow
14925 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14926 change *STRICT_OVERFLOW_P. */
14928 bool
14930 tree type,
14931 tree op0,
14933 {
14936 {
14940 {
14941 /* With the presence of negative values it is hard
14942 to say something. */
14949 /* One of operands must be positive and the other non-negative. */
14950 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14951 overflows, on a twos-complement machine the sum of two
14952 nonnegative numbers can never be zero. */
14954 strict_overflow_p)
14956 strict_overflow_p));
14957 }
14962 {
14964 strict_overflow_p)
14966 strict_overflow_p))
14967 {
14970 }
14971 }
14980 {
14983 }
14990 {
14994 /* When both operands are nonzero, then MAX must be too. */
14996 strict_overflow_p))
14999 /* MAX where operand 0 is positive is positive. */
15001 strict_overflow_p);
15002 }
15003 /* MAX where operand 1 is positive is positive. */
15008 {
15012 }
15017 strict_overflow_p)
15019 strict_overflow_p));
15023 }
15026 }
15028 /* Return true when T is an address and is known to be nonzero.
15029 For floating point we further ensure that T is not denormal.
15030 Similar logic is present in nonzero_address in rtlanal.h.
15032 If the return value is based on the assumption that signed overflow
15033 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15034 change *STRICT_OVERFLOW_P. */
15036 bool
15038 {
15041 {
15046 {
15052 /* Weak declarations may link to NULL. Other things may also be NULL
15053 so protect with -fdelete-null-pointer-checks; but not variables
15054 allocated on the stack. */
15056 && (flag_delete_null_pointer_checks
15060 /* Constants are never weak. */
15065 }
15073 {
15077 }
15082 }
15084 }
15086 /* Return true when T is an address and is known to be nonzero.
15087 For floating point we further ensure that T is not denormal.
15088 Similar logic is present in nonzero_address in rtlanal.h.
15090 If the return value is based on the assumption that signed overflow
15091 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15092 change *STRICT_OVERFLOW_P. */
15094 bool
15096 {
15100 /* Doing something useful for floating point would need more work. */
15106 {
15109 strict_overflow_p);
15115 strict_overflow_p);
15123 }
15126 {
15129 strict_overflow_p);
15137 strict_overflow_p);
15154 strict_overflow_p);
15158 strict_overflow_p);
15165 }
15167 }
15169 /* Return true when T is an address and is known to be nonzero.
15170 Handle warnings about undefined signed overflow. */
15172 bool
15174 {
15181 "determining that expression is always "
15183 WARN_STRICT_OVERFLOW_MISC);
15185 }
15187 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15188 attempt to fold the expression to a constant without modifying TYPE,
15189 OP0 or OP1.
15191 If the expression could be simplified to a constant, then return
15192 the constant. If the expression would not be simplified to a
15193 constant, then return NULL_TREE. */
15195 tree
15197 {
15200 }
15202 /* Given the components of a unary expression CODE, TYPE and OP0,
15203 attempt to fold the expression to a constant without modifying
15204 TYPE or OP0.
15206 If the expression could be simplified to a constant, then return
15207 the constant. If the expression would not be simplified to a
15208 constant, then return NULL_TREE. */
15210 tree
15212 {
15215 }
15217 /* If EXP represents referencing an element in a constant string
15218 (either via pointer arithmetic or array indexing), return the
15219 tree representing the value accessed, otherwise return NULL. */
15221 tree
15223 {
15227 {
15229 tree index;
15230 tree string;
15234 else
15235 {
15239 /* Optimize the special-case of a zero lower bound.
15241 We convert the low_bound to sizetype to avoid some problems
15242 with constant folding. (E.g. suppose the lower bound is 1,
15243 and its mode is QI. Without the conversion,l (ARRAY
15244 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15245 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15250 }
15263 }
15265 }
15267 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15268 an integer constant, real, or fixed-point constant.
15270 TYPE is the type of the result. */
15272 static tree
15274 {
15278 {
15280 {
15282 HOST_WIDE_INT high;
15290 }
15297 {
15298 FIXED_VALUE_TYPE f;
15303 /* Propagate overflow flags. */
15307 }
15311 }
15314 }
15316 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15317 an integer constant or real constant.
15319 TYPE is the type of the result. */
15321 tree
15323 {
15327 {
15329 /* If the value is unsigned, then the absolute value is
15330 the same as the ordinary value. */
15333 /* Similarly, if the value is non-negative. */
15336 /* If the value is negative, then the absolute value is
15337 its negation. */
15338 else
15339 {
15341 HOST_WIDE_INT high;
15347 }
15353 else
15359 }
15362 }
15364 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15365 constant. TYPE is the type of the result. */
15367 static tree
15369 {
15379 }
15381 /* Given CODE, a relational operator, the target type, TYPE and two
15382 constant operands OP0 and OP1, return the result of the
15383 relational operation. If the result is not a compile time
15384 constant, then return NULL_TREE. */
15386 static tree
15388 {
15391 /* From here on, the only cases we handle are when the result is
15392 known to be a constant. */
15395 {
15399 /* Handle the cases where either operand is a NaN. */
15401 {
15403 {
15431 }
15434 }
15437 }
15440 {
15444 }
15446 /* Handle equality/inequality of complex constants. */
15448 {
15459 else
15461 }
15463 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15465 To compute GT, swap the arguments and do LT.
15466 To compute GE, do LT and invert the result.
15467 To compute LE, swap the arguments, do LT and invert the result.
15468 To compute NE, do EQ and invert the result.
15470 Therefore, the code below must handle only EQ and LT. */
15473 {
15478 }
15480 /* Note that it is safe to invert for real values here because we
15481 have already handled the one case that it matters. */
15485 {
15488 }
15490 /* Compute a result for LT or EQ if args permit;
15491 Otherwise return T. */
15493 {
15498 else
15500 }
15501 else
15507 }
15509 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15510 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15511 itself. */
15513 tree
15515 {
15516 /* If the expression does not have side effects then we don't have to wrap
15517 it with a cleanup point expression. */
15521 /* If the expression is a return, check to see if the expression inside the
15522 return has no side effects or the right hand side of the modify expression
15523 inside the return. If either don't have side effects set we don't need to
15524 wrap the expression in a cleanup point expression. Note we don't check the
15525 left hand side of the modify because it should always be a return decl. */
15527 {
15534 }
15537 }
15539 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15540 of an indirection through OP0, or NULL_TREE if no simplification is
15541 possible. */
15543 tree
15545 {
15547 tree subtype;
15555 {
15558 /* *&CONST_DECL -> to the value of the const decl. */
15561 /* *&p => p; make sure to handle *&"str"[cst] here. */
15563 {
15567 else
15569 }
15570 /* *(foo *)&fooarray => fooarray[0] */
15573 {
15579 }
15580 /* *(foo *)&complexfoo => __real__ complexfoo */
15584 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15587 {
15591 }
15592 }
15594 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15597 {
15600 tree op00type;
15607 {
15618 }
15619 }
15622 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15625 {
15628 tree op00type;
15635 {
15639 }
15640 }
15642 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15645 {
15646 tree type_domain;
15653 }
15656 }
15658 /* Builds an expression for an indirection through T, simplifying some
15659 cases. */
15661 tree
15663 {
15669 else
15671 }
15673 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15675 tree
15677 {
15682 else
15684 }
15686 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15687 whose result is ignored. The type of the returned tree need not be
15688 the same as the original expression. */
15690 tree
15692 {
15698 {
15709 else
15715 {
15731 }
15736 }
15737 }
15739 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15740 This can only be applied to objects of a sizetype. */
15742 tree
15744 {
15751 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15752 have to do anything. Only do this when we are not given a const,
15753 because in that case, this check is more expensive than just
15754 doing it. */
15756 {
15761 }
15763 /* If divisor is a power of two, simplify this to bit manipulation. */
15765 {
15767 {
15780 {
15781 high++;
15784 }
15788 }
15789 else
15790 {
15791 tree t;
15797 }
15798 }
15799 else
15800 {
15805 }
15808 }
15810 /* Likewise, but round down. */
15812 tree
15814 {
15821 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15822 have to do anything. Only do this when we are not given a const,
15823 because in that case, this check is more expensive than just
15824 doing it. */
15826 {
15831 }
15833 /* If divisor is a power of two, simplify this to bit manipulation. */
15835 {
15836 tree t;
15840 }
15841 else
15842 {
15847 }
15850 }
15852 /* Returns the pointer to the base of the object addressed by EXP and
15853 extracts the information about the offset of the access, storing it
15854 to PBITPOS and POFFSET. */
15856 static tree
15859 {
15860 tree core;
15863 HOST_WIDE_INT bitsize;
15866 {
15871 }
15872 else
15873 {
15877 }
15880 }
15882 /* Returns true if addresses of E1 and E2 differ by a constant, false
15883 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15885 bool
15887 {
15901 {
15911 }
15913 {
15914 /* If only one of the offsets is non-constant, the difference cannot
15915 be a constant. */
15917 }
15918 else
15923 }
15925 /* Simplify the floating point expression EXP when the sign of the
15926 result is not significant. Return NULL_TREE if no simplification
15927 is possible. */
15929 tree
15931 {
15935 {
15970 {
15973 {
15975 /* Strip copysign function call, return the 1st argument. */
15981 /* Strip sign ops from the argument of "odd" math functions. */
15983 {
15987 }
15989 }
15990 }
15995 }
15997 }