| blob | 433ec6085ab10d1986cb6dac7ece4d4e4314eda3 |
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 };
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;
2330 /* If converting an infinity or NAN to a representation that doesn't
2331 have one, set the overflow bit so that we can produce some kind of
2332 error message at the appropriate point if necessary. It's not the
2333 most user-friendly message, but it's better than nothing. */
2340 /* Regular overflow, conversion produced an infinity in a mode that
2341 can't represent them. */
2346 else
2349 }
2351 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2352 to a floating point type. */
2354 static tree
2356 {
2357 REAL_VALUE_TYPE value;
2358 tree t;
2365 }
2367 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2368 to another fixed-point type. */
2370 static tree
2372 {
2373 FIXED_VALUE_TYPE value;
2374 tree t;
2381 /* Propagate overflow flags. */
2385 }
2387 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2388 to a fixed-point type. */
2390 static tree
2392 {
2393 FIXED_VALUE_TYPE value;
2394 tree t;
2403 /* Propagate overflow flags. */
2407 }
2409 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2410 to a fixed-point type. */
2412 static tree
2414 {
2415 FIXED_VALUE_TYPE value;
2416 tree t;
2424 /* Propagate overflow flags. */
2428 }
2430 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2431 type TYPE. If no simplification can be done return NULL_TREE. */
2433 static tree
2435 {
2441 {
2448 }
2450 {
2457 }
2459 {
2466 }
2468 }
2470 /* Construct a vector of zero elements of vector type TYPE. */
2472 static tree
2474 {
2485 }
2487 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2489 bool
2491 {
2506 {
2525 }
2526 }
2528 /* Convert expression ARG to type TYPE. Used by the middle-end for
2529 simple conversions in preference to calling the front-end's convert. */
2531 tree
2533 {
2535 tree tem;
2549 {
2554 {
2558 }
2563 {
2566 }
2573 {
2577 }
2579 {
2583 }
2585 {
2589 }
2592 {
2610 }
2615 {
2619 }
2622 {
2636 }
2640 {
2649 integer_zero_node));
2651 {
2655 {
2659 }
2667 }
2671 }
2689 }
2690 }
2691 \f
2692 /* Return false if expr can be assumed not to be an lvalue, true
2693 otherwise. */
2695 static bool
2697 {
2698 /* We only need to wrap lvalue tree codes. */
2700 {
2734 /* Assume the worst for front-end tree codes. */
2738 }
2741 }
2743 /* Return an expr equal to X but certainly not valid as an lvalue. */
2745 tree
2747 {
2748 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2749 us. */
2756 }
2758 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2759 Zero means allow extended lvalues. */
2763 /* When pedantic, return an expr equal to X but certainly not valid as a
2764 pedantic lvalue. Otherwise, return X. */
2766 static tree
2768 {
2771 else
2773 }
2774 \f
2775 /* Given a tree comparison code, return the code that is the logical inverse
2776 of the given code. It is not safe to do this for floating-point
2777 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2778 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2780 enum tree_code
2782 {
2787 {
2818 }
2819 }
2821 /* Similar, but return the comparison that results if the operands are
2822 swapped. This is safe for floating-point. */
2824 enum tree_code
2826 {
2828 {
2854 }
2855 }
2858 /* Convert a comparison tree code from an enum tree_code representation
2859 into a compcode bit-based encoding. This function is the inverse of
2860 compcode_to_comparison. */
2862 static enum comparison_code
2864 {
2866 {
2897 }
2898 }
2900 /* Convert a compcode bit-based encoding of a comparison operator back
2901 to GCC's enum tree_code representation. This function is the
2902 inverse of comparison_to_compcode. */
2904 static enum tree_code
2906 {
2908 {
2939 }
2940 }
2942 /* Return a tree for the comparison which is the combination of
2943 doing the AND or OR (depending on CODE) of the two operations LCODE
2944 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2945 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2946 if this makes the transformation invalid. */
2948 tree
2952 {
2959 {
2970 }
2973 {
2974 /* Eliminate unordered comparisons, as well as LTGT and ORD
2975 which are not used unless the mode has NaNs. */
2981 }
2983 {
2984 /* Check that the original operation and the optimized ones will trap
2985 under the same condition. */
2996 /* In a short-circuited boolean expression the LHS might be
2997 such that the RHS, if evaluated, will never trap. For
2998 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2999 if neither x nor y is NaN. (This is a mixed blessing: for
3000 example, the expression above will never trap, hence
3001 optimizing it to x < y would be invalid). */
3006 /* If the comparison was short-circuited, and only the RHS
3007 trapped, we may now generate a spurious trap. */
3012 /* If we changed the conditions that cause a trap, we lose. */
3015 }
3021 else
3022 {
3027 }
3028 }
3029 \f
3030 /* Return nonzero if two operands (typically of the same tree node)
3031 are necessarily equal. If either argument has side-effects this
3032 function returns zero. FLAGS modifies behavior as follows:
3034 If OEP_ONLY_CONST is set, only return nonzero for constants.
3035 This function tests whether the operands are indistinguishable;
3036 it does not test whether they are equal using C's == operation.
3037 The distinction is important for IEEE floating point, because
3038 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3039 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3041 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3042 even though it may hold multiple values during a function.
3043 This is because a GCC tree node guarantees that nothing else is
3044 executed between the evaluation of its "operands" (which may often
3045 be evaluated in arbitrary order). Hence if the operands themselves
3046 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3047 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3048 unset means assuming isochronic (or instantaneous) tree equivalence.
3049 Unless comparing arbitrary expression trees, such as from different
3050 statements, this flag can usually be left unset.
3052 If OEP_PURE_SAME is set, then pure functions with identical arguments
3053 are considered the same. It is used when the caller has other ways
3054 to ensure that global memory is unchanged in between. */
3056 int
3058 {
3059 /* If either is ERROR_MARK, they aren't equal. */
3063 /* Check equality of integer constants before bailing out due to
3064 precision differences. */
3068 /* If both types don't have the same signedness, then we can't consider
3069 them equal. We must check this before the STRIP_NOPS calls
3070 because they may change the signedness of the arguments. As pointers
3071 strictly don't have a signedness, require either two pointers or
3072 two non-pointers as well. */
3077 /* If both types don't have the same precision, then it is not safe
3078 to strip NOPs. */
3085 /* In case both args are comparisons but with different comparison
3086 code, try to swap the comparison operands of one arg to produce
3087 a match and compare that variant. */
3091 {
3099 }
3102 /* This is needed for conversions and for COMPONENT_REF.
3103 Might as well play it safe and always test this. */
3109 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3110 We don't care about side effects in that case because the SAVE_EXPR
3111 takes care of that for us. In all other cases, two expressions are
3112 equal if they have no side effects. If we have two identical
3113 expressions with side effects that should be treated the same due
3114 to the only side effects being identical SAVE_EXPR's, that will
3115 be detected in the recursive calls below. */
3121 /* Next handle constant cases, those for which we can return 1 even
3122 if ONLY_CONST is set. */
3125 {
3140 {
3141 /* If we do not distinguish between signed and unsigned zero,
3142 consider them equal. */
3145 }
3149 {
3155 {
3157 flags))
3161 }
3164 }
3168 flags)
3170 flags));
3183 }
3188 /* Define macros to test an operand from arg0 and arg1 for equality and a
3189 variant that allows null and views null as being different from any
3190 non-null value. In the latter case, if either is null, the both
3191 must be; otherwise, do the normal comparison. */
3192 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3193 TREE_OPERAND (arg1, N), flags)
3195 #define OP_SAME_WITH_NULL(N) \
3196 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3197 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3200 {
3202 /* Two conversions are equal only if signedness and modes match. */
3204 {
3205 CASE_CONVERT:
3213 }
3223 /* For commutative ops, allow the other order. */
3231 /* If either of the pointer (or reference) expressions we are
3232 dereferencing contain a side effect, these cannot be equal. */
3238 {
3248 /* Operands 2 and 3 may be null.
3249 Compare the array index by value if it is constant first as we
3250 may have different types but same value here. */
3259 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3260 may be NULL when we're called to compare MEM_EXPRs. */
3270 }
3274 {
3289 /* Otherwise take into account this is a commutative operation. */
3300 }
3304 {
3306 /* If the CALL_EXPRs call different functions, then they
3307 clearly can not be equal. */
3309 flags))
3312 {
3316 else
3320 }
3322 /* Now see if all the arguments are the same. */
3323 {
3334 /* If we get here and both argument lists are exhausted
3335 then the CALL_EXPRs are equal. */
3337 }
3340 }
3343 /* Consider __builtin_sqrt equal to sqrt. */
3351 }
3353 #undef OP_SAME
3354 #undef OP_SAME_WITH_NULL
3355 }
3356 \f
3357 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3358 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3360 When in doubt, return 0. */
3362 static int
3364 {
3376 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3377 and see if the inner values are the same. This removes any
3378 signedness comparison, which doesn't matter here. */
3385 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3386 actual comparison operand, ARG0.
3388 First throw away any conversions to wider types
3389 already present in the operands. */
3398 {
3401 /* Make sure shorter operand is extended the right way
3402 to match the longer operand. */
3408 }
3411 }
3412 \f
3413 /* See if ARG is an expression that is either a comparison or is performing
3414 arithmetic on comparisons. The comparisons must only be comparing
3415 two different values, which will be stored in *CVAL1 and *CVAL2; if
3416 they are nonzero it means that some operands have already been found.
3417 No variables may be used anywhere else in the expression except in the
3418 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3419 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3421 If this is true, return 1. Otherwise, return zero. */
3423 static int
3425 {
3429 /* We can handle some of the tcc_expression cases here. */
3439 {
3440 /* If we've already found a CVAL1 or CVAL2, this expression is
3441 two complex to handle. */
3447 }
3450 {
3473 /* First see if we can handle the first operand, then the second. For
3474 the second operand, we know *CVAL1 can't be zero. It must be that
3475 one side of the comparison is each of the values; test for the
3476 case where this isn't true by failing if the two operands
3477 are the same. */
3486 ;
3490 ;
3491 else
3495 ;
3499 ;
3500 else
3507 }
3508 }
3509 \f
3510 /* ARG is a tree that is known to contain just arithmetic operations and
3511 comparisons. Evaluate the operations in the tree substituting NEW0 for
3512 any occurrence of OLD0 as an operand of a comparison and likewise for
3513 NEW1 and OLD1. */
3515 static tree
3517 {
3522 /* We can handle some of the tcc_expression cases here. */
3530 {
3545 {
3562 }
3563 /* Fall through - ??? */
3566 {
3570 /* We need to check both for exact equality and tree equality. The
3571 former will be true if the operand has a side-effect. In that
3572 case, we know the operand occurred exactly once. */
3585 }
3589 }
3590 }
3591 \f
3592 /* Return a tree for the case when the result of an expression is RESULT
3593 converted to TYPE and OMITTED was previously an operand of the expression
3594 but is now not needed (e.g., we folded OMITTED * 0).
3596 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3597 the conversion of RESULT to TYPE. */
3599 tree
3601 {
3604 /* If the resulting operand is an empty statement, just return the omitted
3605 statement casted to void. */
3613 }
3615 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3617 static tree
3619 {
3622 /* If the resulting operand is an empty statement, just return the omitted
3623 statement casted to void. */
3631 }
3633 /* Return a tree for the case when the result of an expression is RESULT
3634 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3635 of the expression but are now not needed.
3637 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3638 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3639 evaluated before OMITTED2. Otherwise, if neither has side effects,
3640 just do the conversion of RESULT to TYPE. */
3642 tree
3644 {
3653 }
3655 \f
3656 /* Return a simplified tree node for the truth-negation of ARG. This
3657 never alters ARG itself. We assume that ARG is an operation that
3658 returns a truth value (0 or 1).
3660 FIXME: one would think we would fold the result, but it causes
3661 problems with the dominator optimizer. */
3663 tree
3665 {
3669 /* If this is a comparison, we can simply invert it, except for
3670 floating-point non-equality comparisons, in which case we just
3671 enclose a TRUTH_NOT_EXPR around what we have. */
3674 {
3677 && flag_trapping_math
3690 }
3693 {
3710 /* Here we can invert either operand. We invert the first operand
3711 unless the second operand is a TRUTH_NOT_EXPR in which case our
3712 result is the XOR of the first operand with the inside of the
3713 negation of the second operand. */
3718 else
3740 {
3743 /* A COND_EXPR may have a throw as one operand, which
3744 then has void type. Just leave void operands
3745 as they are. */
3752 }
3762 CASE_CONVERT:
3764 {
3767 }
3769 /* ... fall through ... */
3794 }
3800 }
3802 /* Return a simplified tree node for the truth-negation of ARG. This
3803 never alters ARG itself. We assume that ARG is an operation that
3804 returns a truth value (0 or 1).
3806 FIXME: one would think we would fold the result, but it causes
3807 problems with the dominator optimizer. */
3809 tree
3811 {
3812 tree tem;
3822 }
3824 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3825 operands are another bit-wise operation with a common input. If so,
3826 distribute the bit operations to save an operation and possibly two if
3827 constants are involved. For example, convert
3828 (A | B) & (A | C) into A | (B & C)
3829 Further simplification will occur if B and C are constants.
3831 If this optimization cannot be done, 0 will be returned. */
3833 static tree
3835 {
3836 tree common;
3846 {
3850 }
3852 {
3856 }
3858 {
3862 }
3864 {
3868 }
3869 else
3877 }
3879 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3880 with code CODE. This optimization is unsafe. */
3881 static tree
3883 {
3887 /* (A / C) +- (B / C) -> (A +- B) / C. */
3897 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3902 {
3914 }
3917 }
3918 \f
3919 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3920 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3922 static tree
3925 {
3929 {
3936 }
3950 }
3952 /* Optimize a bit-field compare.
3954 There are two cases: First is a compare against a constant and the
3955 second is a comparison of two items where the fields are at the same
3956 bit position relative to the start of a chunk (byte, halfword, word)
3957 large enough to contain it. In these cases we can avoid the shift
3958 implicit in bitfield extractions.
3960 For constants, we emit a compare of the shifted constant with the
3961 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3962 compared. For two fields at the same position, we do the ANDs with the
3963 similar mask and compare the result of the ANDs.
3965 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3966 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3967 are the left and right operands of the comparison, respectively.
3969 If the optimization described above can be done, we return the resulting
3970 tree. Otherwise we return zero. */
3972 static tree
3975 {
3984 tree mask;
3985 tree offset;
3987 /* Get all the information about the extractions being done. If the bit size
3988 if the same as the size of the underlying object, we aren't doing an
3989 extraction at all and so can do nothing. We also don't want to
3990 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3991 then will no longer be able to replace it. */
3999 {
4000 /* If this is not a constant, we can only do something if bit positions,
4001 sizes, and signedness are the same. */
4009 }
4011 /* See if we can find a mode to refer to this field. We should be able to,
4012 but fail if we can't. */
4021 /* Set signed and unsigned types of the precision of this mode for the
4022 shifts below. */
4026 /* Compute the bit position and size for the new reference and our offset
4027 within it. If the new reference is the same size as the original, we
4028 won't optimize anything, so return zero. */
4038 /* Make the mask to be used against the extracted field. */
4045 /* If not comparing with constant, just rework the comparison
4046 and return. */
4050 unsigned_type,
4053 mask),
4056 unsigned_type,
4059 mask));
4061 /* Otherwise, we are handling the constant case. See if the constant is too
4062 big for the field. Warn and return a tree of for 0 (false) if so. We do
4063 this not only for its own sake, but to avoid having to test for this
4064 error case below. If we didn't, we might generate wrong code.
4066 For unsigned fields, the constant shifted right by the field length should
4067 be all zero. For signed fields, the high-order bits should agree with
4068 the sign bit. */
4071 {
4075 {
4079 }
4080 }
4081 else
4082 {
4086 {
4090 }
4091 }
4093 /* Single-bit compares should always be against zero. */
4095 {
4098 }
4100 /* Make a new bitfield reference, shift the constant over the
4101 appropriate number of bits and mask it with the computed mask
4102 (in case this was a signed field). If we changed it, make a new one. */
4105 {
4108 }
4118 rhs);
4119 }
4120 \f
4121 /* Subroutine for fold_truthop: decode a field reference.
4123 If EXP is a comparison reference, we return the innermost reference.
4125 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4126 set to the starting bit number.
4128 If the innermost field can be completely contained in a mode-sized
4129 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4131 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4132 otherwise it is not changed.
4134 *PUNSIGNEDP is set to the signedness of the field.
4136 *PMASK is set to the mask used. This is either contained in a
4137 BIT_AND_EXPR or derived from the width of the field.
4139 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4141 Return 0 if this is not a component reference or is one that we can't
4142 do anything with. */
4144 static tree
4149 {
4153 tree unsigned_type;
4156 /* All the optimizations using this function assume integer fields.
4157 There are problems with FP fields since the type_for_size call
4158 below can fail for, e.g., XFmode. */
4162 /* We are interested in the bare arrangement of bits, so strip everything
4163 that doesn't affect the machine mode. However, record the type of the
4164 outermost expression if it may matter below. */
4171 {
4177 }
4186 /* If the number of bits in the reference is the same as the bitsize of
4187 the outer type, then the outer type gives the signedness. Otherwise
4188 (in case of a small bitfield) the signedness is unchanged. */
4192 /* Compute the mask to access the bitfield. */
4201 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4209 }
4211 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4212 bit positions. */
4214 static int
4216 {
4219 tree tmask;
4223 return
4230 }
4232 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4233 represents the sign bit of EXP's type. If EXP represents a sign
4234 or zero extension, also test VAL against the unextended type.
4235 The return value is the (sub)expression whose sign bit is VAL,
4236 or NULL_TREE otherwise. */
4238 static tree
4240 {
4244 tree t;
4246 /* Tree EXP must have an integral type. */
4251 /* Tree VAL must be an integer constant. */
4258 {
4265 }
4266 else
4267 {
4274 }
4276 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4277 treat VAL as if it were unsigned. */
4282 /* Handle extension from a narrower type. */
4288 }
4290 /* Subroutine for fold_truthop: determine if an operand is simple enough
4291 to be evaluated unconditionally. */
4293 static int
4295 {
4296 /* Strip any conversions that don't change the machine mode. */
4305 /* Don't regard global variables as simple. They may be
4306 allocated in ways unknown to the compiler (shared memory,
4307 #pragma weak, etc). */
4310 /* Loading a static variable is unduly expensive, but global
4311 registers aren't expensive. */
4313 }
4314 \f
4315 /* The following functions are subroutines to fold_range_test and allow it to
4316 try to change a logical combination of comparisons into a range test.
4318 For example, both
4319 X == 2 || X == 3 || X == 4 || X == 5
4320 and
4321 X >= 2 && X <= 5
4322 are converted to
4323 (unsigned) (X - 2) <= 3
4325 We describe each set of comparisons as being either inside or outside
4326 a range, using a variable named like IN_P, and then describe the
4327 range with a lower and upper bound. If one of the bounds is omitted,
4328 it represents either the highest or lowest value of the type.
4330 In the comments below, we represent a range by two numbers in brackets
4331 preceded by a "+" to designate being inside that range, or a "-" to
4332 designate being outside that range, so the condition can be inverted by
4333 flipping the prefix. An omitted bound is represented by a "-". For
4334 example, "- [-, 10]" means being outside the range starting at the lowest
4335 possible value and ending at 10, in other words, being greater than 10.
4336 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4337 always false.
4339 We set up things so that the missing bounds are handled in a consistent
4340 manner so neither a missing bound nor "true" and "false" need to be
4341 handled using a special case. */
4343 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4344 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4345 and UPPER1_P are nonzero if the respective argument is an upper bound
4346 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4347 must be specified for a comparison. ARG1 will be converted to ARG0's
4348 type if both are specified. */
4350 static tree
4353 {
4354 tree tem;
4358 /* If neither arg represents infinity, do the normal operation.
4359 Else, if not a comparison, return infinity. Else handle the special
4360 comparison rules. Note that most of the cases below won't occur, but
4361 are handled for consistency. */
4364 {
4369 }
4374 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4375 for neither. In real maths, we cannot assume open ended ranges are
4376 the same. But, this is computer arithmetic, where numbers are finite.
4377 We can therefore make the transformation of any unbounded range with
4378 the value Z, Z being greater than any representable number. This permits
4379 us to treat unbounded ranges as equal. */
4383 {
4404 }
4407 }
4408 \f
4409 /* Given EXP, a logical expression, set the range it is testing into
4410 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4411 actually being tested. *PLOW and *PHIGH will be made of the same
4412 type as the returned expression. If EXP is not a comparison, we
4413 will most likely not be returning a useful value and range. Set
4414 *STRICT_OVERFLOW_P to true if the return value is only valid
4415 because signed overflow is undefined; otherwise, do not change
4416 *STRICT_OVERFLOW_P. */
4418 tree
4421 {
4428 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4429 and see if we can refine the range. Some of the cases below may not
4430 happen, but it doesn't seem worth worrying about this. We "continue"
4431 the outer loop when we've changed something; otherwise we "break"
4432 the switch, which will "break" the while. */
4438 {
4443 {
4455 }
4458 {
4465 /* We can only do something if the range is testing for zero
4466 and if the second operand is an integer constant. Note that
4467 saying something is "in" the range we make is done by
4468 complementing IN_P since it will set in the initial case of
4469 being not equal to zero; "out" is leaving it alone. */
4476 {
4497 }
4499 /* If this is an unsigned comparison, we also know that EXP is
4500 greater than or equal to zero. We base the range tests we make
4501 on that fact, so we record it here so we can parse existing
4502 range tests. We test arg0_type since often the return type
4503 of, e.g. EQ_EXPR, is boolean. */
4505 {
4509 NULL_TREE))
4514 /* If the high bound is missing, but we have a nonzero low
4515 bound, reverse the range so it goes from zero to the low bound
4516 minus 1. */
4518 {
4523 }
4524 }
4530 /* (-x) IN [a,b] -> x in [-b, -a] */
4542 /* ~ X -> -X - 1 */
4551 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4552 move a constant to the other side. */
4557 /* If EXP is signed, any overflow in the computation is undefined,
4558 so we don't worry about it so long as our computations on
4559 the bounds don't overflow. For unsigned, overflow is defined
4560 and this is exactly the right thing. */
4572 /* Check for an unsigned range which has wrapped around the maximum
4573 value thus making n_high < n_low, and normalize it. */
4575 {
4581 /* If the range is of the form +/- [ x+1, x ], we won't
4582 be able to normalize it. But then, it represents the
4583 whole range or the empty set, so make it
4584 +/- [ -, - ]. */
4588 else
4590 }
4591 else
4615 /* If we're converting arg0 from an unsigned type, to exp,
4616 a signed type, we will be doing the comparison as unsigned.
4617 The tests above have already verified that LOW and HIGH
4618 are both positive.
4620 So we have to ensure that we will handle large unsigned
4621 values the same way that the current signed bounds treat
4622 negative values. */
4625 {
4626 tree high_positive;
4627 tree equiv_type;
4628 /* For fixed-point modes, we need to pass the saturating flag
4629 as the 2nd parameter. */
4634 else
4638 /* A range without an upper bound is, naturally, unbounded.
4639 Since convert would have cropped a very large value, use
4640 the max value for the destination type. */
4641 high_positive
4648 high_positive),
4651 /* If the low bound is specified, "and" the range with the
4652 range for which the original unsigned value will be
4653 positive. */
4655 {
4659 integer_zero_node),
4660 high_positive))
4664 }
4665 else
4666 {
4667 /* Otherwise, "or" the range with the range of the input
4668 that will be interpreted as negative. */
4672 integer_zero_node),
4673 high_positive))
4677 }
4678 }
4686 }
4689 }
4691 /* If EXP is a constant, we can evaluate whether this is true or false. */
4693 {
4700 }
4704 }
4705 \f
4706 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4707 type, TYPE, return an expression to test if EXP is in (or out of, depending
4708 on IN_P) the range. Return 0 if the test couldn't be created. */
4710 tree
4712 {
4715 #ifdef HAVE_canonicalize_funcptr_for_compare
4716 /* Disable this optimization for function pointer expressions
4717 on targets that require function pointer canonicalization. */
4722 #endif
4725 {
4731 }
4749 {
4751 {
4755 }
4757 }
4759 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4761 {
4763 HOST_WIDE_INT hi;
4768 {
4771 }
4772 else
4773 {
4776 }
4779 {
4781 {
4784 etype
4786 else
4789 }
4792 }
4793 }
4795 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4796 This requires wrap-around arithmetics for the type of the expression.
4797 First make sure that arithmetics in this type is valid, then make sure
4798 that it wraps around. */
4804 {
4807 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4808 for the type in question, as we rely on this here. */
4818 else
4820 }
4830 {
4832 {
4838 }
4840 }
4848 }
4849 \f
4850 /* Return the predecessor of VAL in its type, handling the infinite case. */
4852 static tree
4854 {
4860 else
4862 }
4864 /* Return the successor of VAL in its type, handling the infinite case. */
4866 static tree
4868 {
4874 else
4876 }
4878 /* Given two ranges, see if we can merge them into one. Return 1 if we
4879 can, 0 if we can't. Set the output range into the specified parameters. */
4881 bool
4884 {
4888 tree tem;
4898 /* Make range 0 be the range that starts first, or ends last if they
4899 start at the same value. Swap them if it isn't. */
4902 || (lowequal
4905 {
4909 }
4911 /* Now flag two cases, whether the ranges are disjoint or whether the
4912 second range is totally subsumed in the first. Note that the tests
4913 below are simplified by the ones above. */
4919 /* We now have four cases, depending on whether we are including or
4920 excluding the two ranges. */
4922 {
4923 /* If they don't overlap, the result is false. If the second range
4924 is a subset it is the result. Otherwise, the range is from the start
4925 of the second to the end of the first. */
4930 else
4932 }
4935 {
4936 /* If they don't overlap, the result is the first range. If they are
4937 equal, the result is false. If the second range is a subset of the
4938 first, and the ranges begin at the same place, we go from just after
4939 the end of the second range to the end of the first. If the second
4940 range is not a subset of the first, or if it is a subset and both
4941 ranges end at the same place, the range starts at the start of the
4942 first range and ends just before the second range.
4943 Otherwise, we can't describe this as a single range. */
4949 {
4954 {
4955 /* We are in the weird situation where high0 > high1 but
4956 high1 has no successor. Punt. */
4958 }
4959 }
4961 {
4966 {
4967 /* low0 < low1 but low1 has no predecessor. Punt. */
4969 }
4970 }
4971 else
4973 }
4976 {
4977 /* If they don't overlap, the result is the second range. If the second
4978 is a subset of the first, the result is false. Otherwise,
4979 the range starts just after the first range and ends at the
4980 end of the second. */
4985 else
4986 {
4991 {
4992 /* high1 > high0 but high0 has no successor. Punt. */
4994 }
4995 }
4996 }
4998 else
4999 {
5000 /* The case where we are excluding both ranges. Here the complex case
5001 is if they don't overlap. In that case, the only time we have a
5002 range is if they are adjacent. If the second is a subset of the
5003 first, the result is the first. Otherwise, the range to exclude
5004 starts at the beginning of the first range and ends at the end of the
5005 second. */
5007 {
5012 else
5013 {
5014 /* Canonicalize - [min, x] into - [-, x]. */
5017 {
5022 /* FALLTHROUGH */
5035 }
5037 /* Canonicalize - [x, max] into - [x, -]. */
5040 {
5045 /* FALLTHROUGH */
5060 }
5062 /* The ranges might be also adjacent between the maximum and
5063 minimum values of the given type. For
5064 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5065 return + [x + 1, y - 1]. */
5067 {
5074 }
5075 else
5077 }
5078 }
5081 else
5083 }
5087 }
5088 \f
5090 /* Subroutine of fold, looking inside expressions of the form
5091 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5092 of the COND_EXPR. This function is being used also to optimize
5093 A op B ? C : A, by reversing the comparison first.
5095 Return a folded expression whose code is not a COND_EXPR
5096 anymore, or NULL_TREE if no folding opportunity is found. */
5098 static tree
5100 {
5105 tree tem;
5110 /* If we have A op 0 ? A : -A, consider applying the following
5111 transformations:
5113 A == 0? A : -A same as -A
5114 A != 0? A : -A same as A
5115 A >= 0? A : -A same as abs (A)
5116 A > 0? A : -A same as abs (A)
5117 A <= 0? A : -A same as -abs (A)
5118 A < 0? A : -A same as -abs (A)
5120 None of these transformations work for modes with signed
5121 zeros. If A is +/-0, the first two transformations will
5122 change the sign of the result (from +0 to -0, or vice
5123 versa). The last four will fix the sign of the result,
5124 even though the original expressions could be positive or
5125 negative, depending on the sign of A.
5127 Note that all these transformations are correct if A is
5128 NaN, since the two alternatives (A and -A) are also NaNs. */
5135 /* In the case that A is of the form X-Y, '-A' (arg2) may
5136 have already been folded to Y-X, check for that. */
5144 {
5156 /* Fall through. */
5178 }
5180 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5181 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5182 both transformations are correct when A is NaN: A != 0
5183 is then true, and A == 0 is false. */
5187 {
5192 }
5194 /* Try some transformations of A op B ? A : B.
5196 A == B? A : B same as B
5197 A != B? A : B same as A
5198 A >= B? A : B same as max (A, B)
5199 A > B? A : B same as max (B, A)
5200 A <= B? A : B same as min (A, B)
5201 A < B? A : B same as min (B, A)
5203 As above, these transformations don't work in the presence
5204 of signed zeros. For example, if A and B are zeros of
5205 opposite sign, the first two transformations will change
5206 the sign of the result. In the last four, the original
5207 expressions give different results for (A=+0, B=-0) and
5208 (A=-0, B=+0), but the transformed expressions do not.
5210 The first two transformations are correct if either A or B
5211 is a NaN. In the first transformation, the condition will
5212 be false, and B will indeed be chosen. In the case of the
5213 second transformation, the condition A != B will be true,
5214 and A will be chosen.
5216 The conversions to max() and min() are not correct if B is
5217 a number and A is not. The conditions in the original
5218 expressions will be false, so all four give B. The min()
5219 and max() versions would give a NaN instead. */
5222 /* Avoid these transformations if the COND_EXPR may be used
5223 as an lvalue in the C++ front-end. PR c++/19199. */
5224 && (in_gimple_form
5229 {
5234 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5236 {
5240 }
5243 {
5252 /* In C++ a ?: expression can be an lvalue, so put the
5253 operand which will be used if they are equal first
5254 so that we can convert this back to the
5255 corresponding COND_EXPR. */
5257 {
5264 }
5271 {
5278 }
5291 }
5292 }
5294 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5295 we might still be able to simplify this. For example,
5296 if C1 is one less or one more than C2, this might have started
5297 out as a MIN or MAX and been transformed by this function.
5298 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5304 {
5306 /* We can replace A with C1 in this case. */
5311 /* If C1 is C2 + 1, this is min(A, C2). */
5313 OEP_ONLY_CONST)
5317 OEP_ONLY_CONST))
5319 type,
5321 arg2));
5325 /* If C1 is C2 - 1, this is min(A, C2). */
5327 OEP_ONLY_CONST)
5331 OEP_ONLY_CONST))
5333 type,
5335 arg2));
5339 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5340 MAX_EXPR, to preserve the signedness of the comparison. */
5342 OEP_ONLY_CONST)
5346 OEP_ONLY_CONST))
5349 arg00,
5351 arg2))));
5355 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5357 OEP_ONLY_CONST)
5361 OEP_ONLY_CONST))
5364 arg00,
5366 arg2))));
5372 }
5375 }
5378 \f
5379 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5380 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5381 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5382 false) >= 2)
5383 #endif
5385 /* EXP is some logical combination of boolean tests. See if we can
5386 merge it into some range test. Return the new tree if so. */
5388 static tree
5390 {
5398 tree tem;
5402 /* If this is an OR operation, invert both sides; we will invert
5403 again at the end. */
5407 /* If both expressions are the same, if we can merge the ranges, and we
5408 can build the range test, return it or it inverted. If one of the
5409 ranges is always true or always false, consider it to be the same
5410 expression as the other. */
5418 {
5422 }
5424 /* On machines where the branch cost is expensive, if this is a
5425 short-circuited branch and the underlying object on both sides
5426 is the same, make a non-short-circuit operation. */
5432 {
5433 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5434 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5435 which cases we can't do this. */
5443 {
5452 {
5455 WARN_STRICT_OVERFLOW_COMPARISON);
5459 }
5460 }
5461 }
5464 }
5465 \f
5466 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5467 bit value. Arrange things so the extra bits will be set to zero if and
5468 only if C is signed-extended to its full width. If MASK is nonzero,
5469 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5471 static tree
5473 {
5476 tree temp;
5481 /* We work by getting just the sign bit into the low-order bit, then
5482 into the high-order bit, then sign-extend. We then XOR that value
5483 with C. */
5487 /* We must use a signed type in order to get an arithmetic right shift.
5488 However, we must also avoid introducing accidental overflows, so that
5489 a subsequent call to integer_zerop will work. Hence we must
5490 do the type conversion here. At this point, the constant is either
5491 zero or one, and the conversion to a signed type can never overflow.
5492 We could get an overflow if this conversion is done anywhere else. */
5501 /* If necessary, convert the type back to match the type of C. */
5506 }
5507 \f
5508 /* Find ways of folding logical expressions of LHS and RHS:
5509 Try to merge two comparisons to the same innermost item.
5510 Look for range tests like "ch >= '0' && ch <= '9'".
5511 Look for combinations of simple terms on machines with expensive branches
5512 and evaluate the RHS unconditionally.
5514 For example, if we have p->a == 2 && p->b == 4 and we can make an
5515 object large enough to span both A and B, we can do this with a comparison
5516 against the object ANDed with the a mask.
5518 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5519 operations to do this with one comparison.
5521 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5522 function and the one above.
5524 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5525 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5527 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5528 two operands.
5530 We return the simplified tree or 0 if no optimization is possible. */
5532 static tree
5534 {
5535 /* If this is the "or" of two comparisons, we can do something if
5536 the comparisons are NE_EXPR. If this is the "and", we can do something
5537 if the comparisons are EQ_EXPR. I.e.,
5538 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5540 WANTED_CODE is this operation code. For single bit fields, we can
5541 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5542 comparison for one-bit fields. */
5564 /* Start by getting the comparison codes. Fail if anything is volatile.
5565 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5566 it were surrounded with a NE_EXPR. */
5575 {
5579 }
5582 {
5586 }
5597 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5600 {
5601 tree result;
5604 {
5609 }
5612 {
5618 }
5619 }
5624 /* If the RHS can be evaluated unconditionally and its operands are
5625 simple, it wins to evaluate the RHS unconditionally on machines
5626 with expensive branches. In this case, this isn't a comparison
5627 that can be merged. Avoid doing this if the RHS is a floating-point
5628 comparison since those can trap. */
5635 {
5636 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5647 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5659 {
5663 }
5664 }
5666 /* See if the comparisons can be merged. Then get all the parameters for
5667 each side. */
5691 /* It must be true that the inner operation on the lhs of each
5692 comparison must be the same if we are to be able to do anything.
5693 Then see if we have constants. If not, the same must be true for
5694 the rhs's. */
5705 else
5708 /* If either comparison code is not correct for our logical operation,
5709 fail. However, we can convert a one-bit comparison against zero into
5710 the opposite comparison against that bit being set in the field. */
5714 {
5716 {
5717 /* Make the left operand unsigned, since we are only interested
5718 in the value of one bit. Otherwise we are doing the wrong
5719 thing below. */
5722 }
5723 else
5725 }
5727 /* This is analogous to the code for l_const above. */
5729 {
5731 {
5734 }
5735 else
5737 }
5739 /* See if we can find a mode that contains both fields being compared on
5740 the left. If we can't, fail. Otherwise, update all constants and masks
5741 to be relative to a field of that size. */
5746 volatilep);
5756 {
5759 }
5767 {
5775 {
5779 }
5780 }
5782 {
5790 {
5794 }
5795 }
5797 /* If the right sides are not constant, do the same for it. Also,
5798 disallow this optimization if a size or signedness mismatch occurs
5799 between the left and right sides. */
5801 {
5804 /* Make sure the two fields on the right
5805 correspond to the left without being swapped. */
5813 volatilep);
5823 {
5826 }
5833 /* Make a mask that corresponds to both fields being compared.
5834 Do this for both items being compared. If the operands are the
5835 same size and the bits being compared are in the same position
5836 then we can do this by masking both and comparing the masked
5837 results. */
5841 {
5853 }
5855 /* There is still another way we can do something: If both pairs of
5856 fields being compared are adjacent, we may be able to make a wider
5857 field containing them both.
5859 Note that we still must mask the lhs/rhs expressions. Furthermore,
5860 the mask must be shifted to account for the shift done by
5861 make_bit_field_ref. */
5866 {
5867 tree type;
5879 /* Convert to the smaller type before masking out unwanted bits. */
5882 {
5884 {
5888 }
5890 {
5894 }
5895 }
5904 }
5907 }
5909 /* Handle the case of comparisons with constants. If there is something in
5910 common between the masks, those bits of the constants must be the same.
5911 If not, the condition is always false. Test for this to avoid generating
5912 incorrect code below. */
5917 {
5919 {
5922 }
5923 else
5924 {
5927 }
5928 }
5930 /* Construct the expression we will return. First get the component
5931 reference we will make. Unless the mask is all ones the width of
5932 that field, perform the mask operation. Then compare with the
5933 merged constant. */
5943 }
5944 \f
5945 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5946 constant. */
5948 static tree
5950 {
5953 tree comp_const;
5954 tree minmax_const;
5956 tree inner;
5967 /* If something does not permit us to optimize, return the original tree. */
5975 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5976 and GT_EXPR, doing the rest with recursive calls using logical
5977 simplifications. */
5979 {
5981 {
5987 }
5990 return
5992 optimize_minmax_comparison
5994 optimize_minmax_comparison
5999 /* MAX (X, 0) == 0 -> X <= 0 */
6003 /* MAX (X, 0) == 5 -> X == 5 */
6007 /* MAX (X, 0) == -1 -> false */
6011 /* MIN (X, 0) == 0 -> X >= 0 */
6015 /* MIN (X, 0) == 5 -> false */
6018 else
6019 /* MIN (X, 0) == -1 -> X == -1 */
6024 /* MAX (X, 0) > 0 -> X > 0
6025 MAX (X, 0) > 5 -> X > 5 */
6029 /* MAX (X, 0) > -1 -> true */
6033 /* MIN (X, 0) > 0 -> false
6034 MIN (X, 0) > 5 -> false */
6037 else
6038 /* MIN (X, 0) > -1 -> X > -1 */
6043 }
6044 }
6045 \f
6046 /* T is an integer expression that is being multiplied, divided, or taken a
6047 modulus (CODE says which and what kind of divide or modulus) by a
6048 constant C. See if we can eliminate that operation by folding it with
6049 other operations already in T. WIDE_TYPE, if non-null, is a type that
6050 should be used for the computation if wider than our type.
6052 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6053 (X * 2) + (Y * 4). We must, however, be assured that either the original
6054 expression would not overflow or that overflow is undefined for the type
6055 in the language in question.
6057 If we return a non-null expression, it is an equivalent form of the
6058 original computation, but need not be in the original type.
6060 We set *STRICT_OVERFLOW_P to true if the return values depends on
6061 signed overflow being undefined. Otherwise we do not change
6062 *STRICT_OVERFLOW_P. */
6064 static tree
6067 {
6068 /* To avoid exponential search depth, refuse to allow recursion past
6069 three levels. Beyond that (1) it's highly unlikely that we'll find
6070 something interesting and (2) we've probably processed it before
6071 when we built the inner expression. */
6074 tree ret;
6079 depth++;
6081 depth--;
6084 }
6086 static tree
6089 {
6100 /* Don't deal with constants of zero here; they confuse the code below. */
6110 /* Note that we need not handle conditional operations here since fold
6111 already handles those cases. So just do arithmetic here. */
6113 {
6115 /* For a constant, we can always simplify if we are a multiply
6116 or (for divide and modulus) if it is a multiple of our constant. */
6124 /* If op0 is an expression ... */
6130 /* ... and has wrapping overflow, and its type is smaller
6131 than ctype, then we cannot pass through as widening. */
6137 /* ... or this is a truncation (t is narrower than op0),
6138 then we cannot pass through this narrowing. */
6141 /* ... or signedness changes for division or modulus,
6142 then we cannot pass through this conversion. */
6146 /* ... or has undefined overflow while the converted to
6147 type has not, we cannot do the operation in the inner type
6148 as that would introduce undefined overflow. */
6153 /* Pass the constant down and see if we can make a simplification. If
6154 we can, replace this expression with the inner simplification for
6155 possible later conversion to our or some other type. */
6160 code == MULT_EXPR
6162 strict_overflow_p))))
6167 /* If widening the type changes it from signed to unsigned, then we
6168 must avoid building ABS_EXPR itself as unsigned. */
6170 {
6174 {
6177 }
6179 }
6180 /* If the constant is negative, we cannot simplify this. */
6183 /* FALLTHROUGH */
6191 /* If widening the type changes the signedness, then we can't perform
6192 this optimization as that changes the result. */
6196 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6202 {
6209 }
6213 /* If the second operand is constant, this is a multiplication
6214 or floor division, by a power of two, so we can treat it that
6215 way unless the multiplier or divisor overflows. Signed
6216 left-shift overflow is implementation-defined rather than
6217 undefined in C90, so do not convert signed left shift into
6218 multiplication. */
6221 /* const_binop may not detect overflow correctly,
6222 so check for it explicitly here. */
6227 size_one_node,
6237 /* See if we can eliminate the operation on both sides. If we can, we
6238 can return a new PLUS or MINUS. If we can't, the only remaining
6239 cases where we can do anything are if the second operand is a
6240 constant. */
6246 /* If not multiplication, we can only do this if both operands
6247 are divisible by c. */
6250 {
6255 }
6257 /* If this was a subtraction, negate OP1 and set it to be an addition.
6258 This simplifies the logic below. */
6265 /* If either OP1 or C are negative, this optimization is not safe for
6266 some of the division and remainder types while for others we need
6267 to change the code. */
6269 {
6277 }
6279 /* If it's a multiply or a division/modulus operation of a multiple
6280 of our constant, do the operation and verify it doesn't overflow. */
6283 {
6286 /* We allow the constant to overflow with wrapping semantics. */
6290 }
6291 else
6294 /* If we have an unsigned type is not a sizetype, we cannot widen
6295 the operation since it will change the result if the original
6296 computation overflowed. */
6302 /* If we were able to eliminate our operation from the first side,
6303 apply our operation to the second side and reform the PLUS. */
6307 /* The last case is if we are a multiply. In that case, we can
6308 apply the distributive law to commute the multiply and addition
6309 if the multiplication of the constants doesn't overflow. */
6315 op1);
6320 /* We have a special case here if we are doing something like
6321 (C * 8) % 4 since we know that's zero. */
6324 /* If the multiplication can overflow we cannot optimize this.
6325 ??? Until we can properly mark individual operations as
6326 not overflowing we need to treat sizetype special here as
6327 stor-layout relies on this opimization to make
6328 DECL_FIELD_BIT_OFFSET always a constant. */
6334 {
6337 }
6339 /* ... fall through ... */
6343 /* If we can extract our operation from the LHS, do so and return a
6344 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6345 do something only if the second operand is a constant. */
6359 /* If these are the same operation types, we can associate them
6360 assuming no overflow. */
6372 /* If these operations "cancel" each other, we have the main
6373 optimizations of this pass, which occur when either constant is a
6374 multiple of the other, in which case we replace this with either an
6375 operation or CODE or TCODE.
6377 If we have an unsigned type that is not a sizetype, we cannot do
6378 this since it will change the result if the original computation
6379 overflowed. */
6387 {
6389 {
6396 }
6398 {
6405 }
6406 }
6411 }
6414 }
6415 \f
6416 /* Return a node which has the indicated constant VALUE (either 0 or
6417 1), and is of the indicated TYPE. */
6419 tree
6421 {
6426 else
6428 }
6431 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6432 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6433 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6434 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6435 COND is the first argument to CODE; otherwise (as in the example
6436 given here), it is the second argument. TYPE is the type of the
6437 original expression. Return NULL_TREE if no simplification is
6438 possible. */
6440 static tree
6444 {
6451 /* This transformation is only worthwhile if we don't have to wrap
6452 arg in a SAVE_EXPR, and the operation can be simplified on at least
6453 one of the branches once its pushed inside the COND_EXPR. */
6458 {
6462 /* If this operand throws an expression, then it does not make
6463 sense to try to perform a logical or arithmetic operation
6464 involving it. */
6469 }
6470 else
6471 {
6476 }
6480 {
6484 else
6486 }
6488 {
6492 else
6494 }
6498 }
6500 \f
6501 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6503 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6504 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6505 ADDEND is the same as X.
6507 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6508 and finite. The problematic cases are when X is zero, and its mode
6509 has signed zeros. In the case of rounding towards -infinity,
6510 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6511 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6513 bool
6515 {
6519 /* Don't allow the fold with -fsignaling-nans. */
6523 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6527 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6532 /* The mode has signed zeros, and we have to honor their sign.
6533 In this situation, there is only one case we can return true for.
6534 X - 0 is the same as X unless rounding towards -infinity is
6535 supported. */
6537 }
6539 /* Subroutine of fold() that checks comparisons of built-in math
6540 functions against real constants.
6542 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6543 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6544 is the type of the result and ARG0 and ARG1 are the operands of the
6545 comparison. ARG1 must be a TREE_REAL_CST.
6547 The function returns the constant folded tree if a simplification
6548 can be made, and NULL_TREE otherwise. */
6550 static tree
6553 {
6554 REAL_VALUE_TYPE c;
6557 {
6563 {
6564 /* sqrt(x) < y is always false, if y is negative. */
6568 /* sqrt(x) > y is always true, if y is negative and we
6569 don't care about NaNs, i.e. negative values of x. */
6573 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6576 }
6578 {
6579 REAL_VALUE_TYPE c2;
6585 {
6586 /* sqrt(x) > y is x == +Inf, when y is very large. */
6591 /* sqrt(x) > y is always false, when y is very large
6592 and we don't care about infinities. */
6594 }
6596 /* sqrt(x) > c is the same as x > c*c. */
6599 }
6601 {
6602 REAL_VALUE_TYPE c2;
6608 {
6609 /* sqrt(x) < y is always true, when y is a very large
6610 value and we don't care about NaNs or Infinities. */
6614 /* sqrt(x) < y is x != +Inf when y is very large and we
6615 don't care about NaNs. */
6620 /* sqrt(x) < y is x >= 0 when y is very large and we
6621 don't care about Infinities. */
6626 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6635 dconst0)),
6638 c2)));
6639 }
6641 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6646 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6649 {
6654 dconst0)),
6657 c2)));
6658 }
6659 }
6660 }
6663 }
6665 /* Subroutine of fold() that optimizes comparisons against Infinities,
6666 either +Inf or -Inf.
6668 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6669 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6670 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6672 The function returns the constant folded tree if a simplification
6673 can be made, and NULL_TREE otherwise. */
6675 static tree
6677 {
6679 REAL_VALUE_TYPE max;
6680 tree temp;
6685 /* For negative infinity swap the sense of the comparison. */
6691 {
6693 /* x > +Inf is always false, if with ignore sNANs. */
6699 /* x <= +Inf is always true, if we don't case about NaNs. */
6703 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6706 {
6709 }
6714 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6720 /* x < +Inf is always equal to x <= DBL_MAX. */
6726 /* x != +Inf is always equal to !(x > DBL_MAX). */
6738 }
6741 }
6743 /* Subroutine of fold() that optimizes comparisons of a division by
6744 a nonzero integer constant against an integer constant, i.e.
6745 X/C1 op C2.
6747 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6748 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6749 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6751 The function returns the constant folded tree if a simplification
6752 can be made, and NULL_TREE otherwise. */
6754 static tree
6756 {
6761 HOST_WIDE_INT hpart;
6766 /* We have to do this the hard way to detect unsigned overflow.
6767 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6778 {
6783 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6791 }
6793 {
6797 {
6816 }
6817 }
6818 else
6819 {
6820 /* A negative divisor reverses the relational operators. */
6826 {
6845 }
6846 }
6849 {
6870 {
6873 }
6878 {
6881 }
6886 {
6889 }
6894 {
6897 }
6902 }
6905 }
6908 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6909 equality/inequality test, then return a simplified form of the test
6910 using a sign testing. Otherwise return NULL. TYPE is the desired
6911 result type. */
6913 static tree
6915 tree result_type)
6916 {
6917 /* If this is testing a single bit, we can optimize the test. */
6921 {
6922 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6923 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6927 /* This is only a win if casting to a signed type is cheap,
6928 i.e. when arg00's type is not a partial mode. */
6931 {
6936 }
6937 }
6940 }
6942 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6943 equality/inequality test, then return a simplified form of
6944 the test using shifts and logical operations. Otherwise return
6945 NULL. TYPE is the desired result type. */
6947 tree
6949 tree result_type)
6950 {
6951 /* If this is testing a single bit, we can optimize the test. */
6955 {
6964 /* First, see if we can fold the single bit test into a sign-bit
6965 test. */
6967 result_type);
6971 /* Otherwise we have (A & C) != 0 where C is a single bit,
6972 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6973 Similarly for (A & C) == 0. */
6975 /* If INNER is a right shift of a constant and it plus BITNUM does
6976 not overflow, adjust BITNUM and INNER. */
6983 {
6986 }
6988 /* If we are going to be able to omit the AND below, we must do our
6989 operations as unsigned. If we must use the AND, we have a choice.
6990 Normally unsigned is faster, but for some machines signed is. */
6991 #ifdef LOAD_EXTEND_OP
6994 #else
6996 #endif
7012 /* Put the AND last so it can combine with more things. */
7015 /* Make sure to return the proper type. */
7019 }
7021 }
7023 /* Check whether we are allowed to reorder operands arg0 and arg1,
7024 such that the evaluation of arg1 occurs before arg0. */
7026 static bool
7028 {
7035 }
7037 /* Test whether it is preferable two swap two operands, ARG0 and
7038 ARG1, for example because ARG0 is an integer constant and ARG1
7039 isn't. If REORDER is true, only recommend swapping if we can
7040 evaluate the operands in reverse order. */
7042 bool
7044 {
7080 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7081 for commutative and comparison operators. Ensuring a canonical
7082 form allows the optimizers to find additional redundancies without
7083 having to explicitly check for both orderings. */
7089 /* Put SSA_NAMEs last. */
7095 /* Put variables last. */
7102 }
7104 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7105 ARG0 is extended to a wider type. */
7107 static tree
7109 {
7111 tree arg1_unw;
7120 #ifdef HAVE_canonicalize_funcptr_for_compare
7121 /* Disable this optimization if we're casting a function pointer
7122 type on targets that require function pointer canonicalization. */
7127 #endif
7134 /* If possible, express the comparison in the shorter mode. */
7154 /* If we are comparing with the integer that does not fit into the range
7155 of the shorter type, the result is known. */
7166 {
7193 }
7196 }
7198 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7199 ARG0 just the signedness is changed. */
7201 static tree
7204 {
7205 tree arg0_inner;
7215 #ifdef HAVE_canonicalize_funcptr_for_compare
7216 /* Disable this optimization if we're casting a function pointer
7217 type on targets that require function pointer canonicalization. */
7222 #endif
7242 else
7246 }
7248 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7249 step of the array. Reconstructs s and delta in the case of s * delta
7250 being an integer constant (and thus already folded).
7251 ADDR is the address. MULT is the multiplicative expression.
7252 If the function succeeds, the new address expression is returned. Otherwise
7253 NULL_TREE is returned. */
7255 static tree
7257 {
7261 tree itype;
7264 /* Strip the nops that might be added when converting op1 to sizetype. */
7267 /* Canonicalize op1 into a possibly non-constant delta
7268 and an INTEGER_CST s. */
7270 {
7277 {
7280 }
7282 {
7285 }
7286 else
7288 }
7290 {
7293 }
7294 else
7295 {
7296 /* Simulate we are delta * 1. */
7299 }
7302 {
7304 {
7305 /* Remember if this was a multi-dimensional array. */
7318 {
7321 }
7322 else
7323 {
7324 /* Try if delta is a multiple of step. */
7329 }
7331 /* Only fold here if we can verify we do not overflow one
7332 dimension of a multi-dimensional array. */
7334 {
7335 tree tmp;
7351 }
7354 }
7355 else
7360 }
7362 /* We found the suitable array reference. So copy everything up to it,
7363 and replace the index. */
7370 {
7374 }
7382 }
7385 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7386 means A >= Y && A != MAX, but in this case we know that
7387 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7389 static tree
7391 {
7398 else
7407 {
7410 }
7412 {
7415 }
7416 else
7423 {
7424 /* Convert the pointer types into integer before taking the difference. */
7428 }
7429 else
7436 }
7438 /* Fold a sum or difference of at least one multiplication.
7439 Returns the folded tree or NULL if no simplification could be made. */
7441 static tree
7443 {
7447 /* (A * C) +- (B * C) -> (A+-B) * C.
7448 (A * C) +- A -> A * (C+-1).
7449 We are most concerned about the case where C is a constant,
7450 but other combinations show up during loop reduction. Since
7451 it is not difficult, try all four possibilities. */
7454 {
7457 }
7459 {
7462 }
7463 else
7464 {
7465 /* We cannot generate constant 1 for fract. */
7470 }
7472 {
7475 }
7477 {
7479 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7480 the purpose of this canonicalization. */
7484 {
7487 }
7488 else
7490 }
7491 else
7492 {
7493 /* We cannot generate constant 1 for fract. */
7498 }
7510 /* No identical multiplicands; see if we can find a common
7511 power-of-two factor in non-power-of-two multiplies. This
7512 can help in multi-dimensional array access. */
7515 {
7518 tree maybe_same;
7522 /* Move min of absolute values to int11. */
7525 {
7530 }
7531 else
7535 /* The remainder should not be a constant, otherwise we
7536 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7537 increased the number of multiplications necessary. */
7539 {
7547 }
7548 }
7558 }
7560 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7561 specified by EXPR into the buffer PTR of length LEN bytes.
7562 Return the number of bytes placed in the buffer, or zero
7563 upon failure. */
7565 static int
7567 {
7578 {
7582 else
7587 {
7594 else
7596 }
7597 else
7600 }
7602 }
7605 /* Subroutine of native_encode_expr. Encode the REAL_CST
7606 specified by EXPR into the buffer PTR of length LEN bytes.
7607 Return the number of bytes placed in the buffer, or zero
7608 upon failure. */
7610 static int
7612 {
7618 /* There are always 32 bits in each long, no matter the size of
7619 the hosts long. We handle floating point representations with
7620 up to 192 bits. */
7631 {
7636 {
7643 else
7645 }
7646 else
7649 }
7651 }
7653 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7654 specified by EXPR into the buffer PTR of length LEN bytes.
7655 Return the number of bytes placed in the buffer, or zero
7656 upon failure. */
7658 static int
7660 {
7662 tree part;
7673 }
7676 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7677 specified by EXPR into the buffer PTR of length LEN bytes.
7678 Return the number of bytes placed in the buffer, or zero
7679 upon failure. */
7681 static int
7683 {
7693 {
7695 {
7698 }
7699 else
7703 {
7706 }
7707 else
7708 {
7712 }
7714 }
7716 }
7719 /* Subroutine of native_encode_expr. Encode the STRING_CST
7720 specified by EXPR into the buffer PTR of length LEN bytes.
7721 Return the number of bytes placed in the buffer, or zero
7722 upon failure. */
7724 static int
7726 {
7728 HOST_WIDE_INT total_bytes;
7739 {
7743 }
7744 else
7747 }
7750 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7751 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7752 buffer PTR of length LEN bytes. Return the number of bytes
7753 placed in the buffer, or zero upon failure. */
7755 int
7757 {
7759 {
7777 }
7778 }
7781 /* Subroutine of native_interpret_expr. Interpret the contents of
7782 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7783 If the buffer cannot be interpreted, return NULL_TREE. */
7785 static tree
7787 {
7801 {
7804 {
7811 else
7813 }
7814 else
7820 else
7823 }
7826 }
7829 /* Subroutine of native_interpret_expr. Interpret the contents of
7830 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7831 If the buffer cannot be interpreted, return NULL_TREE. */
7833 static tree
7835 {
7840 /* There are always 32 bits in each long, no matter the size of
7841 the hosts long. We handle floating point representations with
7842 up to 192 bits. */
7843 REAL_VALUE_TYPE r;
7854 {
7857 {
7864 else
7866 }
7867 else
7872 }
7876 }
7879 /* Subroutine of native_interpret_expr. Interpret the contents of
7880 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7881 If the buffer cannot be interpreted, return NULL_TREE. */
7883 static tree
7885 {
7900 }
7903 /* Subroutine of native_interpret_expr. Interpret the contents of
7904 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7905 If the buffer cannot be interpreted, return NULL_TREE. */
7907 static tree
7909 {
7921 {
7926 }
7928 }
7931 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7932 the buffer PTR of length LEN as a constant of type TYPE. For
7933 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7934 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7935 return NULL_TREE. */
7937 tree
7939 {
7941 {
7958 }
7959 }
7962 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7963 TYPE at compile-time. If we're unable to perform the conversion
7964 return NULL_TREE. */
7966 static tree
7968 {
7969 /* We support up to 512-bit values (for V8DFmode). */
7973 /* Check that the host and target are sane. */
7982 }
7984 /* Build an expression for the address of T. Folds away INDIRECT_REF
7985 to avoid confusing the gimplify process. */
7987 tree
7989 {
7990 /* The size of the object is not relevant when talking about its address. */
7994 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7997 {
8002 }
8004 {
8009 }
8010 else
8014 }
8016 /* Build an expression for the address of T. */
8018 tree
8020 {
8024 }
8026 /* Fold a unary expression of code CODE and type TYPE with operand
8027 OP0. Return the folded expression if folding is successful.
8028 Otherwise, return NULL_TREE. */
8030 tree
8032 {
8033 tree tem;
8034 tree arg0;
8042 {
8045 {
8046 /* Don't use STRIP_NOPS, because signedness of argument type
8047 matters. */
8049 }
8050 else
8051 {
8052 /* Strip any conversions that don't change the mode. This
8053 is safe for every expression, except for a comparison
8054 expression because its signedness is derived from its
8055 operands.
8057 Note that this is done as an internal manipulation within
8058 the constant folder, in order to find the simplest
8059 representation of the arguments so that their form can be
8060 studied. In any cases, the appropriate type conversions
8061 should be put back in the tree that will get out of the
8062 constant folder. */
8064 }
8065 }
8068 {
8075 {
8087 /* If this was a conversion, and all we did was to move into
8088 inside the COND_EXPR, bring it back out. But leave it if
8089 it is a conversion from integer to integer and the
8090 result precision is no wider than a word since such a
8091 conversion is cheap and may be optimized away by combine,
8092 while it couldn't if it were outside the COND_EXPR. Then return
8093 so we don't get into an infinite recursion loop taking the
8094 conversion out and then back in. */
8106 && (INTEGRAL_TYPE_P
8118 }
8120 {
8122 {
8126 }
8130 integer_one_node),
8132 integer_zero_node));
8133 }
8134 }
8137 {
8139 /* Re-association barriers around constants and other re-association
8140 barriers can be removed. */
8146 CASE_CONVERT:
8152 /* If we have (type) (a CMP b) and type is an integral type, return
8153 new expression involving the new type. */
8158 /* Handle cases of two conversions in a row. */
8160 {
8182 /* In addition to the cases of two conversions in a row
8183 handled below, if we are converting something to its own
8184 type via an object of identical or wider precision, neither
8185 conversion is needed. */
8192 /* Likewise, if the intermediate and initial types are either both
8193 float or both integer, we don't need the middle conversion if the
8194 former is wider than the latter and doesn't change the signedness
8195 (for integers). Avoid this if the final type is a pointer since
8196 then we sometimes need the middle conversion. Likewise if the
8197 final type has a precision not equal to the size of its mode. */
8206 && ! final_ptr
8210 /* If we have a sign-extension of a zero-extended value, we can
8211 replace that by a single zero-extension. */
8217 /* Two conversions in a row are not needed unless:
8218 - some conversion is floating-point (overstrict for now), or
8219 - some conversion is a vector (overstrict for now), or
8220 - the intermediate type is narrower than both initial and
8221 final, or
8222 - the intermediate type and innermost type differ in signedness,
8223 and the outermost type is wider than the intermediate, or
8224 - the initial type is a pointer type and the precisions of the
8225 intermediate and final types differ, or
8226 - the final type is a pointer type and the precisions of the
8227 initial and intermediate types differ. */
8241 }
8243 /* Handle (T *)&A.B.C for A being of type T and B and C
8244 living at offset zero. This occurs frequently in
8245 C++ upcasting and then accessing the base. */
8249 {
8251 tree offset;
8257 /* If the reference was to a (constant) zero offset, we can use
8258 the address of the base if it has the same base type
8259 as the result type. */
8264 }
8268 /* Detect assigning a bitfield. */
8270 && DECL_BIT_FIELD
8272 {
8273 /* Don't leave an assignment inside a conversion
8274 unless assigning a bitfield. */
8276 /* First do the assignment, then return converted constant. */
8281 }
8283 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8284 constants (if x has signed type, the sign bit cannot be set
8285 in c). This folds extension into the BIT_AND_EXPR.
8286 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8287 very likely don't have maximal range for their precision and this
8288 transformation effectively doesn't preserve non-maximal ranges. */
8292 {
8303 <= HOST_BITS_PER_WIDE_INT
8305 {
8312 #ifdef LOAD_EXTEND_OP
8314 && !flag_syntax_only
8317 {
8321 }
8322 #endif
8323 }
8325 {
8331 }
8332 }
8334 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8335 when one of the new casts will fold away. Conservatively we assume
8336 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8342 {
8348 }
8350 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8351 of the same precision, and X is an integer type not narrower than
8352 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8358 {
8363 }
8365 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8366 type of X and Y (integer types only). */
8371 {
8372 /* Be careful not to introduce new overflows. */
8373 tree mult_type;
8376 else
8380 {
8387 }
8388 }
8403 /* For integral conversions with the same precision or pointer
8404 conversions use a NOP_EXPR instead. */
8412 /* Strip inner integral conversions that do not change the precision. */
8435 /* Convert fabs((double)float) into (double)fabsf(float). */
8438 {
8443 targ0));
8444 }
8445 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8451 /* Strip sign ops from argument. */
8453 {
8457 }
8464 {
8469 }
8471 {
8476 }
8486 /* Convert ~ (-A) to A - 1. */
8491 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8499 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8512 /* Perform BIT_NOT_EXPR on each element individually. */
8514 {
8519 {
8521 {
8527 }
8528 else
8531 }
8534 }
8539 /* The argument to invert_truthvalue must have Boolean type. */
8543 /* Note that the operand of this must be an int
8544 and its values must be 0 or 1.
8545 ("true" is a fixed value perhaps depending on the language,
8546 but we don't handle values other than 1 correctly yet.) */
8561 {
8569 }
8571 {
8575 }
8577 {
8581 {
8590 }
8591 }
8603 {
8611 }
8613 {
8617 }
8619 {
8623 {
8632 }
8633 }
8639 }
8642 /* If the operation was a conversion do _not_ mark a resulting constant
8643 with TREE_OVERFLOW if the original constant was not. These conversions
8644 have implementation defined behavior and retaining the TREE_OVERFLOW
8645 flag here would confuse later passes such as VRP. */
8646 tree
8648 {
8657 }
8659 /* Fold a binary expression of code CODE and type TYPE with operands
8660 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8661 Return the folded expression if folding is successful. Otherwise,
8662 return NULL_TREE. */
8664 static tree
8666 {
8673 else
8676 /* MIN (MAX (a, b), b) == b. */
8681 /* MIN (MAX (b, a), b) == b. */
8687 /* MIN (a, MAX (a, b)) == a. */
8693 /* MIN (a, MAX (b, a)) == a. */
8700 }
8702 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8703 by changing CODE to reduce the magnitude of constants involved in
8704 ARG0 of the comparison.
8705 Returns a canonicalized comparison tree if a simplification was
8706 possible, otherwise returns NULL_TREE.
8707 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8708 valid if signed overflow is undefined. */
8710 static tree
8714 {
8720 /* Match A +- CST code arg1 and CST code arg1. We can change the
8721 first form only if overflow is undefined. */
8723 /* In principle pointers also have undefined overflow behavior,
8724 but that causes problems elsewhere. */
8732 /* Identify the constant in arg0 and its sign. */
8735 else
8739 /* Overflowed constants and zero will cause problems. */
8744 /* See if we can reduce the magnitude of the constant in
8745 arg0 by changing the comparison code. */
8747 {
8748 /* CST <= arg1 -> CST-1 < arg1. */
8751 /* -CST < arg1 -> -CST-1 <= arg1. */
8754 /* CST > arg1 -> CST-1 >= arg1. */
8757 /* -CST >= arg1 -> -CST-1 > arg1. */
8760 else
8762 /* arg1 code' CST' might be more canonical. */
8764 }
8765 else
8766 {
8767 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8771 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8775 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8779 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8783 else
8786 }
8788 /* Now build the constant reduced in magnitude. But not if that
8789 would produce one outside of its types range. */
8797 /* We cannot swap the comparison here as that would cause us to
8798 endlessly recurse. */
8806 /* If swapping might yield to a more canonical form, do so. */
8809 else
8811 }
8813 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8814 overflow further. Try to decrease the magnitude of constants involved
8815 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8816 and put sole constants at the second argument position.
8817 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8819 static tree
8822 {
8823 tree t;
8828 /* Try canonicalization by simplifying arg0. */
8833 {
8837 }
8839 /* Try canonicalization by simplifying arg1 using the swapped
8840 comparison. */
8848 }
8850 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8851 space. This is used to avoid issuing overflow warnings for
8852 expressions like &p->x which can not wrap. */
8854 static bool
8856 {
8867 {
8870 }
8873 else
8874 {
8877 }
8892 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8893 array. */
8895 {
8896 HOST_WIDE_INT base_size;
8901 }
8904 }
8906 /* Subroutine of fold_binary. This routine performs all of the
8907 transformations that are common to the equality/inequality
8908 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8909 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8910 fold_binary should call fold_binary. Fold a comparison with
8911 tree code CODE and type TYPE with operands OP0 and OP1. Return
8912 the folded comparison or NULL_TREE. */
8914 static tree
8916 {
8929 /* If one arg is a real or integer constant, put it last. */
8933 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8940 {
8944 tree lhs;
8951 /* If the constant operation overflowed this can be
8952 simplified as a comparison against INT_MAX/INT_MIN. */
8955 {
8959 /* Get the sign of the constant on the lhs if the
8960 operation were VARIABLE + CONST1. */
8964 /* The sign of the constant determines if we overflowed
8965 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8966 Canonicalize to the INT_MIN overflow by swapping the comparison
8967 if necessary. */
8971 /* We now can look at the canonicalized case
8972 VARIABLE + 1 CODE2 INT_MIN
8973 and decide on the result. */
8982 }
8987 {
8989 "when changing X +- C1 cmp C2 to "
8991 WARN_STRICT_OVERFLOW_COMPARISON);
8993 }
8994 }
8996 /* For comparisons of pointers we can decompose it to a compile time
8997 comparison of the base objects and the offsets into the object.
8998 This requires at least one operand being an ADDR_EXPR or a
8999 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9005 {
9012 /* Get base and offset for the access. Strip ADDR_EXPR for
9013 get_inner_reference, but put it back by stripping INDIRECT_REF
9014 off the base object if possible. indirect_baseN will be true
9015 if baseN is not an address but refers to the object itself. */
9018 {
9024 else
9026 }
9028 {
9031 }
9035 {
9041 else
9043 }
9045 {
9048 }
9050 /* If we have equivalent bases we might be able to simplify. */
9053 {
9054 /* We can fold this expression to a constant if the non-constant
9055 offset parts are equal. */
9063 {
9070 "occur when comparing P +- C1 with "
9072 WARN_STRICT_OVERFLOW_CONDITIONAL);
9075 {
9089 }
9090 }
9091 /* We can simplify the comparison to a comparison of the variable
9092 offset parts if the constant offset parts are equal.
9093 Be careful to use signed size type here because otherwise we
9094 mess with array offsets in the wrong way. This is possible
9095 because pointer arithmetic is restricted to retain within an
9096 object and overflow on pointer differences is undefined as of
9097 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9101 {
9102 tree signed_size_type_node;
9105 /* By converting to signed size type we cover middle-end pointer
9106 arithmetic which operates on unsigned pointer types of size
9107 type size and ARRAY_REF offsets which are properly sign or
9108 zero extended from their type in case it is narrower than
9109 size type. */
9112 else
9116 else
9124 "occur when comparing P +- C1 with "
9126 WARN_STRICT_OVERFLOW_COMPARISON);
9129 }
9130 }
9131 /* For non-equal bases we can simplify if they are addresses
9132 of local binding decls or constants. */
9134 /* We know that !operand_equal_p (base0, base1, 0)
9135 because the if condition was false. But make
9136 sure two decls are not the same. */
9150 {
9155 }
9156 /* For equal offsets we can simplify to a comparison of the
9157 base addresses. */
9159 && (indirect_base0
9161 && (indirect_base1
9166 {
9172 }
9173 }
9175 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9176 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9177 the resulting offset is smaller in absolute value than the
9178 original one. */
9186 {
9191 tree cst;
9193 "occur when combining constants around "
9196 /* Put the constant on the side where it doesn't overflow and is
9197 of lower absolute value than before. */
9203 {
9206 variable1,
9209 }
9216 {
9221 variable2);
9222 }
9223 }
9225 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9226 signed arithmetic case. That form is created by the compiler
9227 often enough for folding it to be of value. One example is in
9228 computing loop trip counts after Operator Strength Reduction. */
9234 {
9243 "eliminating multiplication in comparison "
9245 WARN_STRICT_OVERFLOW_COMPARISON);
9247 /* If const1 is negative we swap the sense of the comparison. */
9252 }
9259 {
9267 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9272 /* (-a) CMP (-b) -> b CMP a */
9279 {
9280 REAL_VALUE_TYPE cst;
9283 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9290 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9291 /* a CMP (-0) -> a CMP 0 */
9296 /* x != NaN is always true, other ops are always false. */
9299 {
9302 }
9304 /* Fold comparisons against infinity. */
9307 {
9311 }
9312 }
9314 /* If this is a comparison of a real constant with a PLUS_EXPR
9315 or a MINUS_EXPR of a real constant, we can convert it into a
9316 comparison with a revised real constant as long as no overflow
9317 occurs when unsafe_math_optimizations are enabled. */
9329 /* Likewise, we can simplify a comparison of a real constant with
9330 a MINUS_EXPR whose first operand is also a real constant, i.e.
9331 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9332 floating-point types only if -fassociative-math is set. */
9343 /* Fold comparisons against built-in math functions. */
9345 && flag_unsafe_math_optimizations
9347 {
9351 {
9355 }
9356 }
9357 }
9361 {
9362 /* If we are widening one operand of an integer comparison,
9363 see if the other operand is similarly being widened. Perhaps we
9364 can do the comparison in the narrower type. */
9369 /* Or if we are changing signedness. */
9373 }
9375 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9376 constant, we can simplify it. */
9381 {
9385 }
9387 /* Simplify comparison of something with itself. (For IEEE
9388 floating-point, we can only do some of these simplifications.) */
9390 {
9392 {
9407 /* For NE, we can only do this simplification if integer
9408 or we don't honor IEEE floating point NaNs. */
9412 /* ... fall through ... */
9418 }
9419 }
9421 /* If we are comparing an expression that just has comparisons
9422 of two integer values, arithmetic expressions of those comparisons,
9423 and constants, we can simplify it. There are only three cases
9424 to check: the two values can either be equal, the first can be
9425 greater, or the second can be greater. Fold the expression for
9426 those three values. Since each value must be 0 or 1, we have
9427 eight possibilities, each of which corresponds to the constant 0
9428 or 1 or one of the six possible comparisons.
9430 This handles common cases like (a > b) == 0 but also handles
9431 expressions like ((x > y) - (y > x)) > 0, which supposedly
9432 occur in macroized code. */
9435 {
9440 /* Don't handle degenerate cases here; they should already
9441 have been handled anyway. */
9450 {
9454 /* We can't just pass T to eval_subst in case cval1 or cval2
9455 was the same as ARG1. */
9457 tree high_result
9461 arg1);
9462 tree equal_result
9466 arg1);
9467 tree low_result
9471 arg1);
9473 /* All three of these results should be 0 or 1. Confirm they are.
9474 Then use those values to select the proper code to use. */
9479 {
9480 /* Make a 3-bit mask with the high-order bit being the
9481 value for `>', the next for '=', and the low for '<'. */
9485 {
9487 /* Always false. */
9508 /* Always true. */
9510 }
9515 }
9516 }
9517 }
9519 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9520 into a single range test. */
9528 {
9532 }
9534 /* Fold ~X op ~Y as Y op X. */
9537 {
9542 }
9544 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9547 {
9553 }
9556 }
9559 /* Subroutine of fold_binary. Optimize complex multiplications of the
9560 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9561 argument EXPR represents the expression "z" of type TYPE. */
9563 static tree
9565 {
9570 {
9573 }
9575 {
9578 }
9579 else
9580 {
9584 }
9593 }
9596 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9597 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9598 guarantees that P and N have the same least significant log2(M) bits.
9599 N is not otherwise constrained. In particular, N is not normalized to
9600 0 <= N < M as is common. In general, the precise value of P is unknown.
9601 M is chosen as large as possible such that constant N can be determined.
9603 Returns M and sets *RESIDUE to N.
9605 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9606 account. This is not always possible due to PR 35705.
9607 */
9609 static unsigned HOST_WIDE_INT
9612 {
9619 {
9622 {
9624 tree offset;
9632 {
9635 else
9636 /* We don't handle more complicated offset expressions. */
9638 }
9639 }
9644 }
9646 {
9654 allow_func_align);
9660 {
9663 }
9665 {
9668 {
9671 /* Compute the greatest power-of-2 divisor of op1. */
9675 /* If align is non-zero and less than *modulus, replace
9676 *modulus with align., If align is 0, then either op1 is 0
9677 or the greatest power-of-2 divisor of op1 doesn't fit in an
9678 unsigned HOST_WIDE_INT. In either case, no additional
9679 constraint is imposed. */
9684 }
9685 }
9686 }
9688 /* If we get here, we were unable to determine anything useful about the
9689 expression. */
9691 }
9694 /* Fold a binary expression of code CODE and type TYPE with operands
9695 OP0 and OP1. Return the folded expression if folding is
9696 successful. Otherwise, return NULL_TREE. */
9698 tree
9700 {
9714 /* Strip any conversions that don't change the mode. This is
9715 safe for every expression, except for a comparison expression
9716 because its signedness is derived from its operands. So, in
9717 the latter case, only strip conversions that don't change the
9718 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9719 preserved.
9721 Note that this is done as an internal manipulation within the
9722 constant folder, in order to find the simplest representation
9723 of the arguments so that their form can be studied. In any
9724 cases, the appropriate type conversions should be put back in
9725 the tree that will get out of the constant folder. */
9728 {
9731 }
9732 else
9733 {
9736 }
9738 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9739 constant but we can't do arithmetic on them. */
9746 {
9748 {
9749 /* Make sure type and arg0 have the same saturating flag. */
9753 }
9756 else
9760 {
9764 }
9765 }
9767 /* If this is a commutative operation, and ARG0 is a constant, move it
9768 to ARG1 to reduce the number of tests below. */
9773 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9775 First check for cases where an arithmetic operation is applied to a
9776 compound, conditional, or comparison operation. Push the arithmetic
9777 operation inside the compound or conditional to see if any folding
9778 can then be done. Convert comparison to conditional for this purpose.
9779 The also optimizes non-constant cases that used to be done in
9780 expand_expr.
9782 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9783 one of the operands is a comparison and the other is a comparison, a
9784 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9785 code below would make the expression more complex. Change it to a
9786 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9787 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9799 {
9803 boolean_type_node,
9811 }
9815 {
9821 op1));
9830 {
9836 }
9839 {
9845 }
9846 }
9849 {
9851 /* 0 +p index -> (type)index */
9855 /* PTR +p 0 -> PTR */
9859 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9866 /* index +p PTR -> PTR +p index */
9873 /* (PTR +p B) +p A -> PTR +p (B + A) */
9875 {
9876 tree inner;
9884 }
9886 /* PTR_CST +p CST -> CST1 */
9890 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9891 of the array. Loop optimizer sometimes produce this type of
9892 expressions. */
9894 {
9898 }
9903 /* A + (-B) -> A - B */
9908 /* (-A) + B -> B - A */
9916 {
9917 /* Convert ~A + 1 to -A. */
9923 /* ~X + X is -1. */
9926 {
9931 {
9934 }
9935 }
9937 /* X + ~X is -1. */
9940 {
9945 {
9948 }
9949 }
9951 /* X + (X / CST) * -CST is X % CST. */
9956 {
9964 }
9965 }
9967 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9968 same or one. Make sure type is not saturating.
9969 fold_plusminus_mult_expr will re-associate. */
9974 {
9978 }
9981 {
9985 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9986 with a constant, and the two constants have no bits in common,
9987 we should treat this as a BIT_IOR_EXPR since this may produce more
9988 simplifications. */
9996 {
9999 }
10001 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10002 (plus (plus (mult) (mult)) (foo)) so that we can
10003 take advantage of the factoring cases below. */
10010 {
10016 else
10038 parg1)));
10039 }
10040 }
10041 else
10042 {
10043 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10047 /* Likewise if the operands are reversed. */
10051 /* Convert X + -C into X - C. */
10054 {
10060 }
10062 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10063 to __complex__ ( x, y ). This is not the same for SNaNs or
10064 if signed zeros are involved. */
10068 {
10075 {
10079 {
10085 }
10087 {
10093 }
10094 }
10095 }
10103 /* Convert x+x into x*2.0. */
10109 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10110 We associate floats only if the user has specified
10111 -fassociative-math. */
10115 {
10120 {
10121 tree tree0;
10124 }
10125 }
10126 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10127 We associate floats only if the user has specified
10128 -fassociative-math. */
10132 {
10137 {
10138 tree tree0;
10141 }
10142 }
10143 }
10145 bit_rotate:
10146 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10147 is a rotate of A by C1 bits. */
10148 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10149 is a rotate of A by B bits. */
10150 {
10152 tree rtype;
10161 /* Only create rotates in complete modes. Other cases are not
10162 expanded properly. */
10164 {
10184 code0 == LSHIFT_EXPR
10187 {
10195 TYPE_PRECISION
10201 ? LROTATE_EXPR
10205 }
10207 {
10215 TYPE_PRECISION
10221 ? 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.
10651 Likewise for complex arithmetic with signed zeros. */
10658 /* Transform x * -1.0 into -x. */
10665 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10666 the result for floating point types due to rounding so it is applied
10667 only if -fassociative-math was specify. */
10672 {
10678 }
10680 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10682 {
10685 {
10688 }
10689 }
10691 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10692 This is not the same for NaNs or if signed zeros are
10693 involved. */
10699 {
10711 }
10713 /* Optimize z * conj(z) for floating point complex numbers.
10714 Guarded by flag_unsafe_math_optimizations as non-finite
10715 imaginary components don't produce scalar results. */
10726 {
10730 /* Optimizations of root(...)*root(...). */
10732 {
10737 /* Optimize sqrt(x)*sqrt(x) as x. */
10743 /* Optimize root(x)*root(y) as root(x*y). */
10747 }
10749 /* Optimize expN(x)*expN(y) as expN(x+y). */
10751 {
10757 }
10759 /* Optimizations of pow(...)*pow(...). */
10763 {
10769 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10771 {
10775 }
10777 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10779 {
10783 }
10784 }
10786 /* Optimize tan(x)*cos(x) as sin(x). */
10795 {
10800 }
10802 /* Optimize x*pow(x,c) as pow(x,c+1). */
10806 {
10812 {
10814 REAL_VALUE_TYPE c;
10815 tree arg;
10821 }
10822 }
10824 /* Optimize pow(x,c)*x as pow(x,c+1). */
10828 {
10834 {
10836 REAL_VALUE_TYPE c;
10837 tree arg;
10843 }
10844 }
10846 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10849 {
10853 {
10856 }
10857 }
10858 }
10859 }
10863 bit_ior:
10871 /* ~X | X is -1. */
10874 {
10878 }
10880 /* X | ~X is -1. */
10883 {
10887 }
10889 /* Canonicalize (X & C1) | C2. */
10893 {
10901 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10906 {
10910 }
10911 else
10912 {
10916 }
10918 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10923 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10924 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10925 mode which allows further optimizations. */
10935 {
10936 unsigned HOST_WIDE_INT mask
10940 {
10944 }
10945 }
10952 arg1);
10953 }
10955 /* (X & Y) | Y is (X, Y). */
10959 /* (X & Y) | X is (Y, X). */
10964 /* X | (X & Y) is (Y, X). */
10969 /* X | (Y & X) is (Y, X). */
10979 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10981 This results in more efficient code for machines without a NAND
10982 instruction. Combine will canonicalize to the first form
10983 which will allow use of NAND instructions provided by the
10984 backend if they exist. */
10987 {
10994 }
10996 /* See if this can be simplified into a rotate first. If that
10997 is unsuccessful continue in the association code. */
11008 /* ~X ^ X is -1. */
11011 {
11015 }
11017 /* X ^ ~X is -1. */
11020 {
11024 }
11026 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11027 with a constant, and the two constants have no bits in common,
11028 we should treat this as a BIT_IOR_EXPR since this may produce more
11029 simplifications. */
11037 {
11040 }
11042 /* (X | Y) ^ X -> Y & ~ X*/
11045 {
11048 arg1);
11052 }
11054 /* (Y | X) ^ X -> Y & ~ X*/
11057 {
11060 arg1);
11064 }
11066 /* X ^ (X | Y) -> Y & ~ X*/
11069 {
11072 arg0);
11076 }
11078 /* X ^ (Y | X) -> Y & ~ X*/
11081 {
11084 arg0);
11088 }
11090 /* Convert ~X ^ ~Y to X ^ Y. */
11097 /* Convert ~X ^ C to X ^ ~C. */
11104 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11111 /* Fold (X & Y) ^ Y as ~X & Y. */
11114 {
11119 }
11120 /* Fold (X & Y) ^ X as ~Y & X. */
11124 {
11129 }
11130 /* Fold X ^ (X & Y) as X & ~Y. */
11133 {
11138 }
11139 /* Fold X ^ (Y & X) as ~Y & X. */
11143 {
11148 }
11150 /* See if this can be simplified into a rotate first. If that
11151 is unsuccessful continue in the association code. */
11162 /* ~X & X is always zero. */
11167 /* X & ~X is always zero. */
11172 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11176 {
11184 }
11186 /* (X | Y) & Y is (X, Y). */
11190 /* (X | Y) & X is (Y, X). */
11195 /* X & (X | Y) is (Y, X). */
11200 /* X & (Y | X) is (Y, X). */
11206 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11210 {
11216 }
11217 /* Fold ~X & 1 as (X & 1) == 0. */
11220 {
11226 }
11228 /* Fold (X ^ Y) & Y as ~X & Y. */
11231 {
11236 }
11237 /* Fold (X ^ Y) & X as ~Y & X. */
11241 {
11246 }
11247 /* Fold X & (X ^ Y) as X & ~Y. */
11250 {
11255 }
11256 /* Fold X & (Y ^ X) as ~Y & X. */
11260 {
11265 }
11270 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11273 {
11274 unsigned int prec
11281 }
11283 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11285 This results in more efficient code for machines without a NOR
11286 instruction. Combine will canonicalize to the first form
11287 which will allow use of NOR instructions provided by the
11288 backend if they exist. */
11291 {
11298 }
11300 /* If arg0 is derived from the address of an object or function, we may
11301 be able to fold this expression using the object or function's
11302 alignment. */
11304 {
11311 /* This works because modulus is a power of 2. If this weren't the
11312 case, we'd have to replace it by its greatest power-of-2
11313 divisor: modulus & -modulus. */
11316 }
11318 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11319 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11320 if the new mask might be further optimized. */
11329 {
11331 unsigned HOST_WIDE_INT mask
11341 {
11344 /* See if more bits can be proven as zero because of
11345 zero extension. */
11348 {
11353 {
11355 /* See if we can shorten the right shift. */
11358 }
11359 }
11363 /* For arithmetic shift if sign bit could be set, zerobits
11364 can contain actually sign bits, so no transformation is
11365 possible, unless MASK masks them all away. In that
11366 case the shift needs to be converted into logical shift. */
11369 {
11372 else
11374 }
11375 }
11377 /* ((X << 16) & 0xff00) is (X, 0). */
11383 {
11386 /* Only do the transformation if NEWMASK is some integer
11387 mode's mask. */
11394 {
11395 tree newmaskt;
11398 {
11404 }
11405 else
11410 }
11411 }
11412 }
11417 /* Don't touch a floating-point divide by zero unless the mode
11418 of the constant can represent infinity. */
11424 /* Optimize A / A to 1.0 if we don't care about
11425 NaNs or Infinities. Skip the transformation
11426 for non-real operands. */
11431 {
11435 }
11437 /* The complex version of the above A / A optimization. */
11440 {
11444 {
11446 /* omit_two_operands will call fold_convert for us. */
11448 }
11449 }
11451 /* (-A) / (-B) -> A / B */
11461 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11466 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11471 /* If ARG1 is a constant, we can convert this to a multiply by the
11472 reciprocal. This does not have the same rounding properties,
11473 so only do this if -freciprocal-math. We can actually
11474 always safely do it if ARG1 is a power of two, but it's hard to
11475 tell if it is or not in a portable manner. */
11477 {
11482 /* Find the reciprocal if optimizing and the result is exact. */
11484 {
11485 REAL_VALUE_TYPE r;
11488 {
11492 }
11493 }
11494 }
11495 /* Convert A/B/C to A/(B*C). */
11502 /* Convert A/(B/C) to (A/B)*C. */
11510 /* Convert C1/(X*C2) into (C1/C2)/X. */
11515 {
11521 }
11524 {
11528 /* Optimize sin(x)/cos(x) as tan(x). */
11534 {
11539 }
11541 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11547 {
11551 {
11555 }
11556 }
11558 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11559 NaNs or Infinities. */
11563 {
11570 {
11575 }
11576 }
11578 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11579 NaNs or Infinities. */
11583 {
11590 {
11594 {
11598 tmp);
11599 }
11600 }
11601 }
11603 /* Optimize pow(x,c)/x as pow(x,c-1). */
11607 {
11613 {
11615 REAL_VALUE_TYPE c;
11616 tree arg;
11622 }
11623 }
11625 /* Optimize a/root(b/c) into a*root(c/b). */
11627 {
11631 {
11640 }
11641 }
11643 /* Optimize x/expN(y) into x*expN(-y). */
11645 {
11650 }
11652 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11656 {
11663 }
11664 }
11669 /* Simplify A / (B << N) where A and B are positive and B is
11670 a power of 2, to A >> (N + log2(B)). */
11675 {
11678 {
11685 WARN_STRICT_OVERFLOW_MISC);
11691 }
11692 }
11694 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11695 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11701 /* Fall thru */
11710 /* X / -1 is -X. */
11717 /* Convert -A / -B to A / B when the type is signed and overflow is
11718 undefined. */
11722 {
11725 "when distributing negation across "
11727 WARN_STRICT_OVERFLOW_MISC);
11731 }
11735 {
11738 "when distributing negation across "
11740 WARN_STRICT_OVERFLOW_MISC);
11744 }
11746 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11747 operation, EXACT_DIV_EXPR.
11749 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11750 At one time others generated faster code, it's not clear if they do
11751 after the last round to changes to the DIV code in expmed.c. */
11760 {
11764 WARN_STRICT_OVERFLOW_MISC);
11766 }
11774 /* X % 1 is always zero, but be sure to preserve any side
11775 effects in X. */
11779 /* X % 0, return X % 0 unchanged so that we can get the
11780 proper warnings and errors. */
11784 /* 0 % X is always zero, but be sure to preserve any side
11785 effects in X. Place this after checking for X == 0. */
11789 /* X % -1 is zero. */
11796 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11797 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11802 {
11804 /* Also optimize A % (C << N) where C is a power of 2,
11805 to A & ((C << N) - 1). */
11810 {
11815 "occur when simplifying "
11817 WARN_STRICT_OVERFLOW_MISC);
11821 }
11822 }
11824 /* X % -C is the same as X % C. */
11831 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11836 /* X % -Y is the same as X % Y. */
11847 {
11851 WARN_STRICT_OVERFLOW_MISC);
11853 }
11864 /* Optimize -1 >> x for arithmetic right shifts. */
11868 /* ... fall through ... */
11871 shift:
11877 /* Since negative shift count is not well-defined,
11878 don't try to compute it in the compiler. */
11882 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11887 {
11891 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11892 being well defined. */
11894 {
11900 else
11902 }
11906 }
11908 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11909 into x & ((unsigned)-1 >> c) for unsigned types. */
11917 {
11920 tree lshift;
11921 tree arg00;
11924 {
11931 }
11932 }
11934 /* Rewrite an LROTATE_EXPR by a constant into an
11935 RROTATE_EXPR by a new constant. */
11937 {
11942 }
11944 /* If we have a rotate of a bit operation with the rotate count and
11945 the second operand of the bit operation both constant,
11946 permute the two operations. */
11958 /* Two consecutive rotates adding up to the precision of the
11959 type can be ignored. */
11970 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11971 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11972 if the latter can be further optimized. */
11977 {
11980 arg1);
11983 arg1);
11987 }
12015 /* Note that the operands of this must be ints
12016 and their values must be 0 or 1.
12017 ("true" is a fixed value perhaps depending on the language.) */
12018 /* If first arg is constant zero, return it. */
12022 /* If either arg is constant true, drop it. */
12026 /* Preserve sequence points. */
12029 /* If second arg is constant zero, result is zero, but first arg
12030 must be evaluated. */
12033 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12034 case will be handled here. */
12038 /* !X && X is always false. */
12042 /* X && !X is always false. */
12047 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12048 means A >= Y && A != MAX, but in this case we know that
12049 A < X <= MAX. */
12053 {
12061 }
12063 truth_andor:
12064 /* We only do these simplifications if we are optimizing. */
12068 /* Check for things like (A || B) && (A || C). We can convert this
12069 to A || (B && C). Note that either operator can be any of the four
12070 truth and/or operations and the transformation will still be
12071 valid. Also note that we only care about order for the
12072 ANDIF and ORIF operators. If B contains side effects, this
12073 might change the truth-value of A. */
12080 {
12100 /* This case if tricky because we must either have commutative
12101 operators or else A10 must not have side-effects. */
12107 a01);
12108 }
12110 /* See if we can build a range comparison. */
12114 /* Check for the possibility of merging component references. If our
12115 lhs is another similar operation, try to merge its rhs with our
12116 rhs. Then try to merge our lhs and rhs. */
12128 /* Note that the operands of this must be ints
12129 and their values must be 0 or true.
12130 ("true" is a fixed value perhaps depending on the language.) */
12131 /* If first arg is constant true, return it. */
12135 /* If either arg is constant zero, drop it. */
12139 /* Preserve sequence points. */
12142 /* If second arg is constant true, result is true, but we must
12143 evaluate first arg. */
12146 /* Likewise for first arg, but note this only occurs here for
12147 TRUTH_OR_EXPR. */
12151 /* !X || X is always true. */
12155 /* X || !X is always true. */
12163 /* If the second arg is constant zero, drop it. */
12166 /* If the second arg is constant true, this is a logical inversion. */
12168 {
12169 /* Only call invert_truthvalue if operand is a truth value. */
12172 else
12175 }
12176 /* Identical arguments cancel to zero. */
12180 /* !X ^ X is always true. */
12185 /* X ^ !X is always true. */
12198 /* bool_var != 0 becomes bool_var. */
12203 /* bool_var == 1 becomes bool_var. */
12208 /* bool_var != 1 becomes !bool_var. */
12213 /* bool_var == 0 becomes !bool_var. */
12218 /* If this is an equality comparison of the address of two non-weak,
12219 unaliased symbols neither of which are extern (since we do not
12220 have access to attributes for externs), then we know the result. */
12233 {
12234 /* We know that we're looking at the address of two
12235 non-weak, unaliased, static _DECL nodes.
12237 It is both wasteful and incorrect to call operand_equal_p
12238 to compare the two ADDR_EXPR nodes. It is wasteful in that
12239 all we need to do is test pointer equality for the arguments
12240 to the two ADDR_EXPR nodes. It is incorrect to use
12241 operand_equal_p as that function is NOT equivalent to a
12242 C equality test. It can in fact return false for two
12243 objects which would test as equal using the C equality
12244 operator. */
12248 type);
12249 }
12251 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12252 a MINUS_EXPR of a constant, we can convert it into a comparison with
12253 a revised constant as long as no overflow occurs. */
12265 /* Similarly for a NEGATE_EXPR. */
12273 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12282 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12289 {
12293 val,
12297 }
12299 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12304 {
12306 code == NE_EXPR
12309 }
12311 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12312 for !=. Don't do this for ordered comparisons due to overflow. */
12318 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12323 /* If this is an EQ or NE comparison with zero and ARG0 is
12324 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12325 two operations, but the latter can be done in one less insn
12326 on machines that have only two-operand insns or on which a
12327 constant cannot be the first operand. */
12330 {
12335 {
12342 }
12345 {
12352 }
12353 }
12355 /* If this is an NE or EQ comparison of zero against the result of a
12356 signed MOD operation whose second operand is a power of 2, make
12357 the MOD operation unsigned since it is simpler and equivalent. */
12365 {
12375 }
12377 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12378 C1 is a valid shift constant, and C2 is a power of two, i.e.
12379 a single bit. */
12383 == INTEGER_CST
12386 {
12391 /* Check for a valid shift count. */
12394 {
12398 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12399 can be rewritten as (X & (C2 << C1)) != 0. */
12401 {
12405 }
12406 /* Otherwise, for signed (arithmetic) shifts,
12407 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12408 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12412 /* Otherwise, of unsigned (logical) shifts,
12413 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12414 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12415 else
12419 arg000);
12420 }
12421 }
12423 /* If this is an NE comparison of zero with an AND of one, remove the
12424 comparison since the AND will give the correct value. */
12431 /* If we have (A & C) == C where C is a power of 2, convert this into
12432 (A & C) != 0. Similarly for NE_EXPR. */
12438 integer_zero_node));
12440 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12441 bit, then fold the expression into A < 0 or A >= 0. */
12446 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12447 Similarly for NE_EXPR. */
12451 {
12460 }
12462 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12463 Similarly for NE_EXPR. */
12467 {
12474 }
12476 /* If this is a comparison of a field, we may be able to simplify it. */
12479 /* Handle the constant case even without -O
12480 to make sure the warnings are given. */
12482 {
12486 }
12488 /* Optimize comparisons of strlen vs zero to a compare of the
12489 first character of the string vs zero. To wit,
12490 strlen(ptr) == 0 => *ptr == 0
12491 strlen(ptr) != 0 => *ptr != 0
12492 Other cases should reduce to one of these two (or a constant)
12493 due to the return value of strlen being unsigned. */
12496 {
12504 {
12508 }
12509 }
12511 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12512 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12516 {
12523 {
12525 {
12528 }
12531 }
12532 }
12534 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12540 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12545 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12552 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12560 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12561 (X & C) == 0 when C is a single bit. */
12566 {
12572 }
12574 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12575 constant C is a power of two, i.e. a single bit. */
12582 {
12586 }
12588 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12589 when is C is a power of two, i.e. a single bit. */
12596 {
12602 }
12606 {
12609 }
12611 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12618 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12621 {
12633 arg01),
12641 arg01),
12649 arg00),
12657 arg00),
12659 }
12663 {
12670 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12671 operand_equal_p guarantees no side-effects so we don't need
12672 to use omit_one_operand on Z. */
12682 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12689 arg10);
12690 }
12692 /* Attempt to simplify equality/inequality comparisons of complex
12693 values. Only lower the comparison if the result is known or
12694 can be simplified to a single scalar comparison. */
12699 {
12704 {
12707 }
12708 else
12709 {
12712 }
12715 {
12718 }
12719 else
12720 {
12723 }
12727 {
12729 {
12734 }
12735 else
12736 {
12741 }
12742 }
12746 {
12748 {
12753 }
12754 else
12755 {
12760 }
12761 }
12762 }
12774 /* Transform comparisons of the form X +- C CMP X. */
12781 {
12788 else
12791 /* (X - c) > X becomes false. */
12795 {
12799 "occur when assuming that (X - c) > X "
12801 WARN_STRICT_OVERFLOW_ALL);
12803 }
12805 /* Likewise (X + c) < X becomes false. */
12809 {
12813 "occur when assuming that "
12815 WARN_STRICT_OVERFLOW_ALL);
12817 }
12819 /* Convert (X - c) <= X to true. */
12824 {
12828 "occur when assuming that "
12830 WARN_STRICT_OVERFLOW_ALL);
12832 }
12834 /* Convert (X + c) >= X to true. */
12839 {
12843 "occur when assuming that "
12845 WARN_STRICT_OVERFLOW_ALL);
12847 }
12850 {
12851 /* Convert X + c > X and X - c < X to true for integers. */
12855 {
12858 "not occur when assuming that "
12860 WARN_STRICT_OVERFLOW_ALL);
12862 }
12867 {
12870 "not occur when assuming that "
12872 WARN_STRICT_OVERFLOW_ALL);
12874 }
12876 /* Convert X + c <= X and X - c >= X to false for integers. */
12880 {
12883 "not occur when assuming that "
12885 WARN_STRICT_OVERFLOW_ALL);
12887 }
12892 {
12895 "not occur when assuming that "
12897 WARN_STRICT_OVERFLOW_ALL);
12899 }
12900 }
12901 }
12903 /* Comparisons with the highest or lowest possible integer of
12904 the specified precision will have known values. */
12905 {
12912 {
12913 HOST_WIDE_INT signed_max_hi;
12918 {
12925 {
12929 }
12930 else
12931 {
12935 }
12936 }
12937 else
12938 {
12947 {
12950 }
12951 else
12952 {
12955 }
12956 }
12961 {
12974 /* The GE_EXPR and LT_EXPR cases above are not normally
12975 reached because of previous transformations. */
12979 }
12981 == max_hi
12984 {
12990 arg1);
12996 arg1);
12999 }
13001 == min_hi
13004 {
13019 }
13021 == min_hi
13024 {
13029 arg1);
13034 arg1);
13037 }
13042 /* We will flip the signedness of the comparison operator
13043 associated with the mode of arg1, so the sign bit is
13044 specified by this mode. Check that arg1 is the signed
13045 max associated with this sign bit. */
13047 /* signed_type does not work on pointer types. */
13049 {
13050 /* The following case also applies to X < signed_max+1
13051 and X >= signed_max+1 because previous transformations. */
13053 {
13054 tree st;
13059 }
13060 }
13061 }
13062 }
13064 /* If we are comparing an ABS_EXPR with a constant, we can
13065 convert all the cases into explicit comparisons, but they may
13066 well not be faster than doing the ABS and one comparison.
13067 But ABS (X) <= C is a range comparison, which becomes a subtraction
13068 and a comparison, and is probably faster. */
13082 /* Convert ABS_EXPR<x> >= 0 to true. */
13089 {
13092 "when simplifying comparison of "
13094 WARN_STRICT_OVERFLOW_CONDITIONAL);
13096 }
13098 /* Convert ABS_EXPR<x> < 0 to false. */
13103 {
13106 "when simplifying comparison of "
13108 WARN_STRICT_OVERFLOW_CONDITIONAL);
13110 }
13112 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13113 and similarly for >= into !=. */
13128 return
13147 {
13151 }
13153 /* If the first operand is NaN, the result is constant. */
13157 {
13159 ? integer_zero_node
13162 }
13164 /* If the second operand is NaN, the result is constant. */
13168 {
13170 ? integer_zero_node
13173 }
13175 /* Simplify unordered comparison of something with itself. */
13181 && !flag_trapping_math
13185 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13186 {
13197 }
13202 /* When pedantic, a compound expression can be neither an lvalue
13203 nor an integer constant expression. */
13206 /* Don't let (0, 0) be null pointer constant. */
13220 /* An ASSERT_EXPR should never be passed to fold_binary. */
13226 }
13228 /* Callback for walk_tree, looking for LABEL_EXPR.
13229 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13230 Do not check the sub-tree of GOTO_EXPR. */
13232 static tree
13236 {
13238 {
13243 /* no break */
13246 }
13247 }
13249 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13250 accessible from outside the sub-tree. Returns NULL_TREE if no
13251 addressable label is found. */
13253 static bool
13255 {
13257 }
13259 /* Fold a ternary expression of code CODE and type TYPE with operands
13260 OP0, OP1, and OP2. Return the folded expression if folding is
13261 successful. Otherwise, return NULL_TREE. */
13263 tree
13265 {
13266 tree tem;
13273 /* Strip any conversions that don't change the mode. This is safe
13274 for every expression, except for a comparison expression because
13275 its signedness is derived from its operands. So, in the latter
13276 case, only strip conversions that don't change the signedness.
13278 Note that this is done as an internal manipulation within the
13279 constant folder, in order to find the simplest representation of
13280 the arguments so that their form can be studied. In any cases,
13281 the appropriate type conversions should be put back in the tree
13282 that will get out of the constant folder. */
13284 {
13287 }
13290 {
13293 }
13296 {
13300 {
13306 }
13310 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13311 so all simple results must be passed through pedantic_non_lvalue. */
13313 {
13316 /* Only optimize constant conditions when the selected branch
13317 has the same type as the COND_EXPR. This avoids optimizing
13318 away "c ? x : throw", where the throw has a void type.
13319 Avoid throwing away that operand which contains label. */
13326 }
13330 /* If we have A op B ? A : C, we may be able to convert this to a
13331 simpler expression, depending on the operation and the values
13332 of B and C. Signed zeros prevent all of these transformations,
13333 for reasons given above each one.
13335 Also try swapping the arguments and inverting the conditional. */
13340 {
13344 }
13348 op2,
13351 {
13354 {
13358 }
13359 }
13361 /* If the second operand is simpler than the third, swap them
13362 since that produces better jump optimization results. */
13365 {
13366 /* See if this can be inverted. If it can't, possibly because
13367 it was a floating-point inequality comparison, don't do
13368 anything. */
13372 }
13374 /* Convert A ? 1 : 0 to simply A. */
13377 /* If we try to convert OP0 to our type, the
13378 call to fold will try to move the conversion inside
13379 a COND, which will recurse. In that case, the COND_EXPR
13380 is probably the best choice, so leave it alone. */
13384 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13385 over COND_EXPR in cases such as floating point comparisons. */
13392 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13397 {
13398 /* sign_bit_p only checks ARG1 bits within A's precision.
13399 If <sign bit of A> has wider type than A, bits outside
13400 of A's precision in <sign bit of A> need to be checked.
13401 If they are all 0, this optimization needs to be done
13402 in unsigned A's type, if they are all 1 in signed A's type,
13403 otherwise this can't be done. */
13408 {
13410 HOST_WIDE_INT mask_hi;
13412 tree tem_type;
13420 {
13424 }
13425 else
13426 {
13430 }
13432 {
13436 }
13437 else
13443 {
13446 }
13449 {
13452 }
13453 else
13455 }
13462 arg1)));
13463 }
13465 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13466 already handled above. */
13471 {
13480 }
13482 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13483 is probably obsolete because the first operand should be a
13484 truth value (that's why we have the two cases above), but let's
13485 leave it in until we can confirm this for all front-ends. */
13496 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13502 arg1);
13504 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13508 {
13509 /* Only perform transformation if ARG0 is easily inverted. */
13514 arg1);
13515 }
13517 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13521 {
13522 /* Only perform transformation if ARG0 is easily inverted. */
13527 op2);
13528 }
13530 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13536 op2);
13541 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13542 of fold_ternary on them. */
13549 {
13558 {
13563 else
13564 {
13566 tree value;
13570 }
13575 else
13577 }
13578 }
13580 /* A bit-field-ref that referenced the full argument can be stripped. */
13591 }
13593 /* Perform constant folding and related simplification of EXPR.
13594 The related simplifications include x*1 => x, x*0 => 0, etc.,
13595 and application of the associative law.
13596 NOP_EXPR conversions may be removed freely (as long as we
13597 are careful not to change the type of the overall expression).
13598 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13599 but we can constant-fold them if they have constant operands. */
13601 #ifdef ENABLE_FOLD_CHECKING
13602 # define fold(x) fold_1 (x)
13604 static
13605 #endif
13606 tree
13608 {
13612 tree tem;
13614 /* Return right away if a constant. */
13618 /* CALL_EXPR-like objects with variable numbers of operands are
13619 treated specially. */
13621 {
13623 {
13626 }
13628 }
13631 {
13636 {
13654 }
13655 }
13658 {
13660 {
13667 {
13672 /* Find a matching index by means of a binary search. */
13674 {
13690 else
13692 }
13693 }
13696 }
13704 }
13706 #ifdef ENABLE_FOLD_CHECKING
13707 #undef fold
13713 /* When --enable-checking=fold, compute a digest of expr before
13714 and after actual fold call to see if fold did not accidentally
13715 change original expr. */
13717 tree
13719 {
13720 tree ret;
13723 htab_t ht;
13742 }
13744 void
13746 {
13749 htab_t ht;
13759 }
13761 static void
13763 {
13765 }
13767 static void
13769 {
13775 recursive_label:
13789 {
13790 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13794 }
13801 {
13802 /* Allow these fields to be modified. */
13803 tree tmp;
13811 {
13814 }
13815 }
13824 {
13827 {
13841 }
13845 {
13858 }
13875 {
13881 }
13886 {
13890 }
13901 {
13904 }
13914 }
13915 }
13917 /* Helper function for outputting the checksum of a tree T. When
13918 debugging with gdb, you can "define mynext" to be "next" followed
13919 by "call debug_fold_checksum (op0)", then just trace down till the
13920 outputs differ. */
13922 void
13924 {
13939 }
13941 #endif
13943 /* Fold a unary tree expression with code CODE of type TYPE with an
13944 operand OP0. Return a folded expression if successful. Otherwise,
13945 return a tree expression with code CODE of type TYPE with an
13946 operand OP0. */
13948 tree
13950 {
13951 tree tem;
13952 #ifdef ENABLE_FOLD_CHECKING
13955 htab_t ht;
13962 #endif
13968 #ifdef ENABLE_FOLD_CHECKING
13976 #endif
13978 }
13980 /* Fold a binary tree expression with code CODE of type TYPE with
13981 operands OP0 and OP1. Return a folded expression if successful.
13982 Otherwise, return a tree expression with code CODE of type TYPE
13983 with operands OP0 and OP1. */
13985 tree
13987 MEM_STAT_DECL)
13988 {
13989 tree tem;
13990 #ifdef ENABLE_FOLD_CHECKING
13996 htab_t ht;
14008 #endif
14014 #ifdef ENABLE_FOLD_CHECKING
14030 #endif
14032 }
14034 /* Fold a ternary tree expression with code CODE of type TYPE with
14035 operands OP0, OP1, and OP2. Return a folded expression if
14036 successful. Otherwise, return a tree expression with code CODE of
14037 type TYPE with operands OP0, OP1, and OP2. */
14039 tree
14041 MEM_STAT_DECL)
14042 {
14043 tree tem;
14044 #ifdef ENABLE_FOLD_CHECKING
14052 htab_t ht;
14069 #endif
14076 #ifdef ENABLE_FOLD_CHECKING
14100 #endif
14102 }
14104 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14105 arguments in ARGARRAY, and a null static chain.
14106 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14107 of type TYPE from the given operands as constructed by build_call_array. */
14109 tree
14111 {
14112 tree tem;
14113 #ifdef ENABLE_FOLD_CHECKING
14119 htab_t ht;
14133 #endif
14137 #ifdef ENABLE_FOLD_CHECKING
14154 #endif
14156 }
14158 /* Perform constant folding and related simplification of initializer
14159 expression EXPR. These behave identically to "fold_buildN" but ignore
14160 potential run-time traps and exceptions that fold must preserve. */
14162 #define START_FOLD_INIT \
14163 int saved_signaling_nans = flag_signaling_nans;\
14164 int saved_trapping_math = flag_trapping_math;\
14165 int saved_rounding_math = flag_rounding_math;\
14166 int saved_trapv = flag_trapv;\
14167 int saved_folding_initializer = folding_initializer;\
14168 flag_signaling_nans = 0;\
14169 flag_trapping_math = 0;\
14170 flag_rounding_math = 0;\
14171 flag_trapv = 0;\
14172 folding_initializer = 1;
14174 #define END_FOLD_INIT \
14175 flag_signaling_nans = saved_signaling_nans;\
14176 flag_trapping_math = saved_trapping_math;\
14177 flag_rounding_math = saved_rounding_math;\
14178 flag_trapv = saved_trapv;\
14179 folding_initializer = saved_folding_initializer;
14181 tree
14183 {
14184 tree result;
14185 START_FOLD_INIT;
14189 END_FOLD_INIT;
14191 }
14193 tree
14195 {
14196 tree result;
14197 START_FOLD_INIT;
14201 END_FOLD_INIT;
14203 }
14205 tree
14207 tree op2)
14208 {
14209 tree result;
14210 START_FOLD_INIT;
14214 END_FOLD_INIT;
14216 }
14218 tree
14221 {
14222 tree result;
14223 START_FOLD_INIT;
14227 END_FOLD_INIT;
14229 }
14231 #undef START_FOLD_INIT
14232 #undef END_FOLD_INIT
14234 /* Determine if first argument is a multiple of second argument. Return 0 if
14235 it is not, or we cannot easily determined it to be.
14237 An example of the sort of thing we care about (at this point; this routine
14238 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14239 fold cases do now) is discovering that
14241 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14243 is a multiple of
14245 SAVE_EXPR (J * 8)
14247 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14249 This code also handles discovering that
14251 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14253 is a multiple of 8 so we don't have to worry about dealing with a
14254 possible remainder.
14256 Note that we *look* inside a SAVE_EXPR only to determine how it was
14257 calculated; it is not safe for fold to do much of anything else with the
14258 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14259 at run time. For example, the latter example above *cannot* be implemented
14260 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14261 evaluation time of the original SAVE_EXPR is not necessarily the same at
14262 the time the new expression is evaluated. The only optimization of this
14263 sort that would be valid is changing
14265 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14267 divided by 8 to
14269 SAVE_EXPR (I) * SAVE_EXPR (J)
14271 (where the same SAVE_EXPR (J) is used in the original and the
14272 transformed version). */
14274 int
14276 {
14284 {
14286 /* Bitwise and provides a power of two multiple. If the mask is
14287 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14290 /* FALLTHRU */
14303 {
14307 /* const_binop may not detect overflow correctly,
14308 so check for it explicitly here. */
14314 size_one_node,
14318 }
14322 /* Can't handle conversions from non-integral or wider integral type. */
14328 /* .. fall through ... */
14345 }
14346 }
14348 /* Return true if CODE or TYPE is known to be non-negative. */
14350 static bool
14352 {
14355 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14356 have a signed:1 type (where the value is -1 and 0). */
14359 }
14361 /* Return true if (CODE OP0) is known to be non-negative. If the return
14362 value is based on the assumption that signed overflow is undefined,
14363 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14364 *STRICT_OVERFLOW_P. */
14366 bool
14369 {
14374 {
14376 /* We can't return 1 if flag_wrapv is set because
14377 ABS_EXPR<INT_MIN> = INT_MIN. */
14381 {
14384 }
14391 strict_overflow_p);
14394 {
14399 {
14402 strict_overflow_p);
14404 {
14408 strict_overflow_p);
14409 }
14410 }
14412 {
14415 strict_overflow_p);
14419 }
14420 }
14425 }
14427 /* We don't know sign of `t', so be conservative and return false. */
14429 }
14431 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14432 value is based on the assumption that signed overflow is undefined,
14433 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14434 *STRICT_OVERFLOW_P. */
14436 bool
14439 {
14444 {
14449 strict_overflow_p)
14451 strict_overflow_p));
14453 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14454 both unsigned and at least 2 bits shorter than the result. */
14458 {
14463 {
14467 }
14468 }
14473 {
14474 /* x * x for floating point x is always non-negative. */
14478 strict_overflow_p)
14480 strict_overflow_p));
14481 }
14483 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14484 both unsigned and their total bits is shorter than the result. */
14488 {
14507 {
14517 }
14518 }
14524 strict_overflow_p)
14526 strict_overflow_p));
14537 strict_overflow_p)
14539 strict_overflow_p));
14546 strict_overflow_p);
14549 }
14551 /* We don't know sign of `t', so be conservative and return false. */
14553 }
14555 /* Return true if T is known to be non-negative. If the return
14556 value is based on the assumption that signed overflow is undefined,
14557 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14558 *STRICT_OVERFLOW_P. */
14560 bool
14562 {
14567 {
14579 strict_overflow_p)
14581 strict_overflow_p));
14585 }
14586 /* We don't know sign of `t', so be conservative and return false. */
14588 }
14590 /* Return true if T is known to be non-negative. If the return
14591 value is based on the assumption that signed overflow is undefined,
14592 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14593 *STRICT_OVERFLOW_P. */
14595 bool
14598 {
14601 {
14619 /* Always true. */
14623 /* sqrt(-0.0) is -0.0. */
14627 strict_overflow_p);
14660 /* True if the 1st argument is nonnegative. */
14662 strict_overflow_p);
14665 /* True if the 1st OR 2nd arguments are nonnegative. */
14667 strict_overflow_p)
14669 strict_overflow_p)));
14672 /* True if the 1st AND 2nd arguments are nonnegative. */
14674 strict_overflow_p)
14676 strict_overflow_p)));
14679 /* True if the 2nd argument is nonnegative. */
14681 strict_overflow_p);
14684 /* True if the 1st argument is nonnegative or the second
14685 argument is an even integer. */
14690 strict_overflow_p);
14693 /* True if the 1st argument is nonnegative or the second
14694 argument is an even integer valued real. */
14696 {
14697 REAL_VALUE_TYPE c;
14698 HOST_WIDE_INT n;
14703 {
14704 REAL_VALUE_TYPE cint;
14709 }
14710 }
14712 strict_overflow_p);
14716 }
14718 type);
14719 }
14721 /* Return true if T is known to be non-negative. If the return
14722 value is based on the assumption that signed overflow is undefined,
14723 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14724 *STRICT_OVERFLOW_P. */
14726 bool
14728 {
14734 {
14736 {
14740 /* If the initializer is non-void, then it's a normal expression
14741 that will be assigned to the slot. */
14745 /* Otherwise, the initializer sets the slot in some way. One common
14746 way is an assignment statement at the end of the initializer. */
14748 {
14756 else
14758 }
14762 strict_overflow_p);
14765 }
14768 {
14774 arg0,
14775 arg1,
14776 strict_overflow_p);
14777 }
14781 strict_overflow_p);
14784 strict_overflow_p);
14787 strict_overflow_p);
14792 }
14794 /* We don't know sign of `t', so be conservative and return false. */
14796 }
14798 /* Return true if T is known to be non-negative. If the return
14799 value is based on the assumption that signed overflow is undefined,
14800 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14801 *STRICT_OVERFLOW_P. */
14803 bool
14805 {
14812 {
14819 strict_overflow_p);
14825 strict_overflow_p);
14834 }
14837 {
14845 strict_overflow_p);
14850 strict_overflow_p);
14865 }
14866 }
14868 /* Return true if `t' is known to be non-negative. Handle warnings
14869 about undefined signed overflow. */
14871 bool
14873 {
14880 "determining that expression is always "
14882 WARN_STRICT_OVERFLOW_MISC);
14884 }
14887 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14888 For floating point we further ensure that T is not denormal.
14889 Similar logic is present in nonzero_address in rtlanal.h.
14891 If the return value is based on the assumption that signed overflow
14892 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14893 change *STRICT_OVERFLOW_P. */
14895 bool
14898 {
14900 {
14903 strict_overflow_p);
14906 {
14912 strict_overflow_p));
14913 }
14918 strict_overflow_p);
14922 }
14925 }
14927 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14928 For floating point we further ensure that T is not denormal.
14929 Similar logic is present in nonzero_address in rtlanal.h.
14931 If the return value is based on the assumption that signed overflow
14932 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14933 change *STRICT_OVERFLOW_P. */
14935 bool
14937 tree type,
14938 tree op0,
14940 {
14943 {
14947 {
14948 /* With the presence of negative values it is hard
14949 to say something. */
14956 /* One of operands must be positive and the other non-negative. */
14957 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14958 overflows, on a twos-complement machine the sum of two
14959 nonnegative numbers can never be zero. */
14961 strict_overflow_p)
14963 strict_overflow_p));
14964 }
14969 {
14971 strict_overflow_p)
14973 strict_overflow_p))
14974 {
14977 }
14978 }
14987 {
14990 }
14997 {
15001 /* When both operands are nonzero, then MAX must be too. */
15003 strict_overflow_p))
15006 /* MAX where operand 0 is positive is positive. */
15008 strict_overflow_p);
15009 }
15010 /* MAX where operand 1 is positive is positive. */
15015 {
15019 }
15024 strict_overflow_p)
15026 strict_overflow_p));
15030 }
15033 }
15035 /* Return true when T is an address and is known to be nonzero.
15036 For floating point we further ensure that T is not denormal.
15037 Similar logic is present in nonzero_address in rtlanal.h.
15039 If the return value is based on the assumption that signed overflow
15040 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15041 change *STRICT_OVERFLOW_P. */
15043 bool
15045 {
15048 {
15053 {
15059 /* Weak declarations may link to NULL. Other things may also be NULL
15060 so protect with -fdelete-null-pointer-checks; but not variables
15061 allocated on the stack. */
15063 && (flag_delete_null_pointer_checks
15067 /* Constants are never weak. */
15072 }
15080 {
15084 }
15089 }
15091 }
15093 /* Return true when T is an address and is known to be nonzero.
15094 For floating point we further ensure that T is not denormal.
15095 Similar logic is present in nonzero_address in rtlanal.h.
15097 If the return value is based on the assumption that signed overflow
15098 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15099 change *STRICT_OVERFLOW_P. */
15101 bool
15103 {
15107 /* Doing something useful for floating point would need more work. */
15113 {
15116 strict_overflow_p);
15122 strict_overflow_p);
15130 }
15133 {
15136 strict_overflow_p);
15144 strict_overflow_p);
15161 strict_overflow_p);
15165 strict_overflow_p);
15172 }
15174 }
15176 /* Return true when T is an address and is known to be nonzero.
15177 Handle warnings about undefined signed overflow. */
15179 bool
15181 {
15188 "determining that expression is always "
15190 WARN_STRICT_OVERFLOW_MISC);
15192 }
15194 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15195 attempt to fold the expression to a constant without modifying TYPE,
15196 OP0 or OP1.
15198 If the expression could be simplified to a constant, then return
15199 the constant. If the expression would not be simplified to a
15200 constant, then return NULL_TREE. */
15202 tree
15204 {
15207 }
15209 /* Given the components of a unary expression CODE, TYPE and OP0,
15210 attempt to fold the expression to a constant without modifying
15211 TYPE or OP0.
15213 If the expression could be simplified to a constant, then return
15214 the constant. If the expression would not be simplified to a
15215 constant, then return NULL_TREE. */
15217 tree
15219 {
15222 }
15224 /* If EXP represents referencing an element in a constant string
15225 (either via pointer arithmetic or array indexing), return the
15226 tree representing the value accessed, otherwise return NULL. */
15228 tree
15230 {
15234 {
15236 tree index;
15237 tree string;
15241 else
15242 {
15246 /* Optimize the special-case of a zero lower bound.
15248 We convert the low_bound to sizetype to avoid some problems
15249 with constant folding. (E.g. suppose the lower bound is 1,
15250 and its mode is QI. Without the conversion,l (ARRAY
15251 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15252 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15257 }
15270 }
15272 }
15274 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15275 an integer constant, real, or fixed-point constant.
15277 TYPE is the type of the result. */
15279 static tree
15281 {
15285 {
15287 {
15289 HOST_WIDE_INT high;
15297 }
15304 {
15305 FIXED_VALUE_TYPE f;
15310 /* Propagate overflow flags. */
15314 }
15318 }
15321 }
15323 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15324 an integer constant or real constant.
15326 TYPE is the type of the result. */
15328 tree
15330 {
15334 {
15336 /* If the value is unsigned, then the absolute value is
15337 the same as the ordinary value. */
15340 /* Similarly, if the value is non-negative. */
15343 /* If the value is negative, then the absolute value is
15344 its negation. */
15345 else
15346 {
15348 HOST_WIDE_INT high;
15354 }
15360 else
15366 }
15369 }
15371 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15372 constant. TYPE is the type of the result. */
15374 static tree
15376 {
15386 }
15388 /* Given CODE, a relational operator, the target type, TYPE and two
15389 constant operands OP0 and OP1, return the result of the
15390 relational operation. If the result is not a compile time
15391 constant, then return NULL_TREE. */
15393 static tree
15395 {
15398 /* From here on, the only cases we handle are when the result is
15399 known to be a constant. */
15402 {
15406 /* Handle the cases where either operand is a NaN. */
15408 {
15410 {
15438 }
15441 }
15444 }
15447 {
15451 }
15453 /* Handle equality/inequality of complex constants. */
15455 {
15466 else
15468 }
15470 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15472 To compute GT, swap the arguments and do LT.
15473 To compute GE, do LT and invert the result.
15474 To compute LE, swap the arguments, do LT and invert the result.
15475 To compute NE, do EQ and invert the result.
15477 Therefore, the code below must handle only EQ and LT. */
15480 {
15485 }
15487 /* Note that it is safe to invert for real values here because we
15488 have already handled the one case that it matters. */
15492 {
15495 }
15497 /* Compute a result for LT or EQ if args permit;
15498 Otherwise return T. */
15500 {
15505 else
15507 }
15508 else
15514 }
15516 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15517 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15518 itself. */
15520 tree
15522 {
15523 /* If the expression does not have side effects then we don't have to wrap
15524 it with a cleanup point expression. */
15528 /* If the expression is a return, check to see if the expression inside the
15529 return has no side effects or the right hand side of the modify expression
15530 inside the return. If either don't have side effects set we don't need to
15531 wrap the expression in a cleanup point expression. Note we don't check the
15532 left hand side of the modify because it should always be a return decl. */
15534 {
15541 }
15544 }
15546 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15547 of an indirection through OP0, or NULL_TREE if no simplification is
15548 possible. */
15550 tree
15552 {
15554 tree subtype;
15562 {
15565 /* *&CONST_DECL -> to the value of the const decl. */
15568 /* *&p => p; make sure to handle *&"str"[cst] here. */
15570 {
15574 else
15576 }
15577 /* *(foo *)&fooarray => fooarray[0] */
15580 {
15586 }
15587 /* *(foo *)&complexfoo => __real__ complexfoo */
15591 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15594 {
15598 }
15599 }
15601 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15604 {
15607 tree op00type;
15614 {
15625 }
15626 }
15629 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15632 {
15635 tree op00type;
15642 {
15646 }
15647 }
15649 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15652 {
15653 tree type_domain;
15660 }
15663 }
15665 /* Builds an expression for an indirection through T, simplifying some
15666 cases. */
15668 tree
15670 {
15676 else
15678 }
15680 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15682 tree
15684 {
15689 else
15691 }
15693 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15694 whose result is ignored. The type of the returned tree need not be
15695 the same as the original expression. */
15697 tree
15699 {
15705 {
15716 else
15722 {
15738 }
15743 }
15744 }
15746 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15747 This can only be applied to objects of a sizetype. */
15749 tree
15751 {
15758 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15759 have to do anything. Only do this when we are not given a const,
15760 because in that case, this check is more expensive than just
15761 doing it. */
15763 {
15768 }
15770 /* If divisor is a power of two, simplify this to bit manipulation. */
15772 {
15774 {
15787 {
15788 high++;
15791 }
15795 }
15796 else
15797 {
15798 tree t;
15804 }
15805 }
15806 else
15807 {
15812 }
15815 }
15817 /* Likewise, but round down. */
15819 tree
15821 {
15828 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15829 have to do anything. Only do this when we are not given a const,
15830 because in that case, this check is more expensive than just
15831 doing it. */
15833 {
15838 }
15840 /* If divisor is a power of two, simplify this to bit manipulation. */
15842 {
15843 tree t;
15847 }
15848 else
15849 {
15854 }
15857 }
15859 /* Returns the pointer to the base of the object addressed by EXP and
15860 extracts the information about the offset of the access, storing it
15861 to PBITPOS and POFFSET. */
15863 static tree
15866 {
15867 tree core;
15870 HOST_WIDE_INT bitsize;
15873 {
15878 }
15879 else
15880 {
15884 }
15887 }
15889 /* Returns true if addresses of E1 and E2 differ by a constant, false
15890 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15892 bool
15894 {
15908 {
15918 }
15920 {
15921 /* If only one of the offsets is non-constant, the difference cannot
15922 be a constant. */
15924 }
15925 else
15930 }
15932 /* Simplify the floating point expression EXP when the sign of the
15933 result is not significant. Return NULL_TREE if no simplification
15934 is possible. */
15936 tree
15938 {
15942 {
15977 {
15980 {
15982 /* Strip copysign function call, return the 1st argument. */
15988 /* Strip sign ops from the argument of "odd" math functions. */
15990 {
15994 }
15996 }
15997 }
16002 }
16004 }