| blob | dd2f62d4a4b4b44ab4b2387ae876cdb438c91205 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide, size_binop
31 and force_fit_type_double.
33 fold takes a tree as argument and returns a simplified tree.
35 size_binop takes a tree code for an arithmetic operation
36 and two operands that are trees, and produces a tree for the
37 result, assuming the type comes from `sizetype'.
39 size_int takes an integer value, and creates a tree constant
40 with type from `sizetype'.
42 force_fit_type_double takes a constant, an overflowable flag and a
43 prior overflow indicator. It forces the value to fit the type and
44 sets TREE_OVERFLOW.
46 Note: Since the folders get called on non-gimple code as well as
47 gimple code, we need to handle GIMPLE tuples as well as their
48 corresponding tree equivalents. */
70 /* Nonzero if we are folding constants inside an initializer; zero
71 otherwise. */
74 /* The following constants represent a bit based encoding of GCC's
75 comparison operators. This encoding simplifies transformations
76 on relational comparison operators, such as AND and OR. */
94 };
125 tree);
147 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
148 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
149 and SUM1. Then this yields nonzero if overflow occurred during the
150 addition.
152 Overflow occurs if A and B have the same sign, but A and SUM differ in
153 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
154 sign. */
155 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
156 \f
157 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
158 We do that by representing the two-word integer in 4 words, with only
159 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
160 number. The value of the word is LOWPART + HIGHPART * BASE. */
162 #define LOWPART(x) \
163 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
164 #define HIGHPART(x) \
165 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
166 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
168 /* Unpack a two-word integer into 4 words.
169 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
170 WORDS points to the array of HOST_WIDE_INTs. */
172 static void
174 {
179 }
181 /* Pack an array of 4 words into a two-word integer.
182 WORDS points to the array of words.
183 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
185 static void
188 {
191 }
192 \f
193 /* Force the double-word integer L1, H1 to be within the range of the
194 integer type TYPE. Stores the properly truncated and sign-extended
195 double-word integer in *LV, *HV. Returns true if the operation
196 overflows, that is, argument and result are different. */
198 int
201 {
210 else
213 /* Size types *are* sign extended. */
218 /* First clear all bits that are beyond the type's precision. */
220 ;
223 else
224 {
228 }
230 /* Then do sign extension if necessary. */
236 {
237 /* Sign extend top half? */
241 }
243 {
246 }
247 else
248 {
249 /* Sign extend bottom half? */
251 {
254 }
255 }
260 /* If the value didn't fit, signal overflow. */
262 }
264 /* We force the double-int HIGH:LOW to the range of the type TYPE by
265 sign or zero extending it.
266 OVERFLOWABLE indicates if we are interested
267 in overflow of the value, when >0 we are only interested in signed
268 overflow, for <0 we are interested in any overflow. OVERFLOWED
269 indicates whether overflow has already occurred. CONST_OVERFLOWED
270 indicates whether constant overflow has already occurred. We force
271 T's value to be within range of T's type (by setting to 0 or 1 all
272 the bits outside the type's range). We set TREE_OVERFLOWED if,
273 OVERFLOWED is nonzero,
274 or OVERFLOWABLE is >0 and signed overflow occurs
275 or OVERFLOWABLE is <0 and any overflow occurs
276 We return a new tree node for the extended double-int. The node
277 is shared if no overflow flags are set. */
279 tree
283 {
287 /* Size types *are* sign extended. */
294 /* If we need to set overflow flags, return a new unshared node. */
296 {
300 {
307 }
308 }
310 /* Else build a shared node. */
312 }
313 \f
314 /* Add two doubleword integers with doubleword result.
315 Return nonzero if the operation overflows according to UNSIGNED_P.
316 Each argument is given as two `HOST_WIDE_INT' pieces.
317 One argument is L1 and H1; the other, L2 and H2.
318 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
320 int
325 {
327 HOST_WIDE_INT h;
337 else
339 }
341 /* Negate a doubleword integer with doubleword result.
342 Return nonzero if the operation overflows, assuming it's signed.
343 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
344 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
346 int
349 {
351 {
355 }
356 else
357 {
361 }
362 }
363 \f
364 /* Multiply two doubleword integers with doubleword result.
365 Return nonzero if the operation overflows according to UNSIGNED_P.
366 Each argument is given as two `HOST_WIDE_INT' pieces.
367 One argument is L1 and H1; the other, L2 and H2.
368 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
370 int
375 {
390 {
393 {
395 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
397 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
401 }
403 }
408 /* Unsigned overflow is immediate. */
412 /* Check for signed overflow by calculating the signed representation of the
413 top half of the result; it should agree with the low half's sign bit. */
415 {
418 }
420 {
423 }
425 }
426 \f
427 /* Shift the doubleword integer in L1, H1 left by COUNT places
428 keeping only PREC bits of result.
429 Shift right if COUNT is negative.
430 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
431 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
433 void
437 {
441 {
444 }
450 {
451 /* Shifting by the host word size is undefined according to the
452 ANSI standard, so we must handle this as a special case. */
455 }
457 {
460 }
461 else
462 {
466 }
468 /* Sign extend all bits that are beyond the precision. */
476 ;
478 {
481 }
482 else
483 {
487 }
488 }
490 /* Shift the doubleword integer in L1, H1 right by COUNT places
491 keeping only PREC bits of result. COUNT must be positive.
492 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
493 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
495 void
500 {
503 signmask = (arith
511 {
512 /* Shifting by the host word size is undefined according to the
513 ANSI standard, so we must handle this as a special case. */
516 }
518 {
521 }
522 else
523 {
527 }
529 /* Zero / sign extend all bits that are beyond the precision. */
532 {
535 }
537 ;
539 {
542 }
543 else
544 {
548 }
549 }
550 \f
551 /* Rotate the doubleword integer in L1, H1 left by COUNT places
552 keeping only PREC bits of result.
553 Rotate right if COUNT is negative.
554 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
556 void
560 {
572 }
574 /* Rotate the doubleword integer in L1, H1 left by COUNT places
575 keeping only PREC bits of result. COUNT must be positive.
576 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
578 void
582 {
594 }
595 \f
596 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
597 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
598 CODE is a tree code for a kind of division, one of
599 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
600 or EXACT_DIV_EXPR
601 It controls how the quotient is rounded to an integer.
602 Return nonzero if the operation overflows.
603 UNS nonzero says do unsigned division. */
605 int
608 HOST_WIDE_INT hnum_orig,
610 HOST_WIDE_INT hden_orig,
614 {
630 /* Calculate quotient sign and convert operands to unsigned. */
632 {
634 {
636 /* (minimum integer) / (-1) is the only overflow case. */
640 }
642 {
645 }
646 }
651 /* This unsigned division rounds toward zero. */
654 }
658 /* hden != 0 already checked. */
663 }
673 /* Special code for when the divisor < BASE. */
675 {
676 /* hnum != 0 already checked. */
678 {
682 }
683 }
684 else
685 {
686 /* Full double precision division,
687 with thanks to Don Knuth's "Seminumerical Algorithms". */
691 /* Find the highest nonzero divisor digit. */
694 {
697 }
699 /* Insure that the first digit of the divisor is at least BASE/2.
700 This is required by the quotient digit estimation algorithm. */
707 {
711 }
716 {
721 }
722 }
726 /* Main loop */
728 {
729 /* Guess the next quotient digit, quo_est, by dividing the first
730 two remaining dividend digits by the high order quotient digit.
731 quo_est is never low and is at most 2 high. */
738 else
741 /* Refine quo_est so it's usually correct, and at most one high. */
746 quo_est--;
748 /* Try QUO_EST as the quotient digit, by multiplying the
749 divisor by QUO_EST and subtracting from the remaining dividend.
750 Keep in mind that QUO_EST is the I - 1st digit. */
754 {
760 }
762 /* If quo_est was high by one, then num[i] went negative and
763 we need to correct things. */
765 {
766 quo_est--;
769 {
773 }
776 }
778 /* Store the quotient digit. */
780 }
781 }
785 finish_up:
786 /* If result is negative, make it so. */
790 /* Compute trial remainder: rem = num - (quo * den) */
796 {
805 {
806 /* quo = quo - 1; */
809 }
810 else
817 {
820 }
821 else
827 {
833 /* Get absolute values. */
839 /* If (2 * abs (lrem) >= abs (lden)), adjust the quotient. */
848 {
850 /* quo = quo - 1; */
853 else
854 /* quo = quo + 1; */
857 }
858 else
860 }
865 }
867 /* Compute true remainder: rem = num - (quo * den) */
872 }
874 /* If ARG2 divides ARG1 with zero remainder, carries out the division
875 of type CODE and returns the quotient.
876 Otherwise returns NULL_TREE. */
878 tree
880 {
890 /* &obj[0] + -128 really should be compiled as &obj[-8] rather than
891 &obj[some_exotic_number]. */
893 {
897 type);
898 }
899 else
910 }
911 \f
912 /* This is nonzero if we should defer warnings about undefined
913 overflow. This facility exists because these warnings are a
914 special case. The code to estimate loop iterations does not want
915 to issue any warnings, since it works with expressions which do not
916 occur in user code. Various bits of cleanup code call fold(), but
917 only use the result if it has certain characteristics (e.g., is a
918 constant); that code only wants to issue a warning if the result is
919 used. */
923 /* If a warning about undefined overflow is deferred, this is the
924 warning. Note that this may cause us to turn two warnings into
925 one, but that is fine since it is sufficient to only give one
926 warning per expression. */
930 /* If a warning about undefined overflow is deferred, this is the
931 level at which the warning should be emitted. */
935 /* Start deferring overflow warnings. We could use a stack here to
936 permit nested calls, but at present it is not necessary. */
938 void
940 {
942 }
944 /* Stop deferring overflow warnings. If there is a pending warning,
945 and ISSUE is true, then issue the warning if appropriate. STMT is
946 the statement with which the warning should be associated (used for
947 location information); STMT may be NULL. CODE is the level of the
948 warning--a warn_strict_overflow_code value. This function will use
949 the smaller of CODE and the deferred code when deciding whether to
950 issue the warning. CODE may be zero to mean to always use the
951 deferred code. */
953 void
955 {
957 location_t locus;
962 {
968 }
979 /* Use the smallest code level when deciding to issue the
980 warning. */
989 else
992 }
994 /* Stop deferring overflow warnings, ignoring any deferred
995 warnings. */
997 void
999 {
1001 }
1003 /* Whether we are deferring overflow warnings. */
1005 bool
1007 {
1009 }
1011 /* This is called when we fold something based on the fact that signed
1012 overflow is undefined. */
1014 static void
1016 {
1018 {
1021 {
1024 }
1025 }
1028 }
1029 \f
1030 /* Return true if the built-in mathematical function specified by CODE
1031 is odd, i.e. -f(x) == f(-x). */
1033 static bool
1035 {
1037 {
1071 }
1073 }
1075 /* Check whether we may negate an integer constant T without causing
1076 overflow. */
1078 bool
1080 {
1083 tree type;
1093 {
1098 }
1099 else
1104 }
1106 /* Determine whether an expression T can be cheaply negated using
1107 the function negate_expr without introducing undefined overflow. */
1109 static bool
1111 {
1112 tree type;
1121 {
1126 /* Check that -CST will not overflow type. */
1152 /* -(A + B) -> (-B) - A. */
1157 /* -(A + B) -> (-A) - B. */
1161 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1171 /* Fall through. */
1184 /* In general we can't negate A / B, because if A is INT_MIN and
1185 B is 1, we may turn this into INT_MIN / -1 which is undefined
1186 and actually traps on some architectures. But if overflow is
1187 undefined, we can negate, because - (INT_MIN / 1) is an
1188 overflow. */
1196 /* Negate -((double)float) as (double)(-float). */
1198 {
1202 }
1206 /* Negate -f(x) as f(-x). */
1212 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1214 {
1220 }
1225 }
1227 }
1229 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1230 simplification is possible.
1231 If negate_expr_p would return true for T, NULL_TREE will never be
1232 returned. */
1234 static tree
1236 {
1238 tree tem;
1241 {
1242 /* Convert - (~A) to A + 1. */
1258 /* Two's complement FP formats, such as c4x, may overflow. */
1268 {
1277 }
1299 {
1300 /* -(A + B) -> (-B) - A. */
1304 {
1308 }
1310 /* -(A + B) -> (-A) - B. */
1312 {
1316 }
1317 }
1321 /* - (A - B) -> B - A */
1333 /* Fall through. */
1337 {
1346 }
1354 /* In general we can't negate A / B, because if A is INT_MIN and
1355 B is 1, we may turn this into INT_MIN / -1 which is undefined
1356 and actually traps on some architectures. But if overflow is
1357 undefined, we can negate, because - (INT_MIN / 1) is an
1358 overflow. */
1360 {
1365 {
1372 }
1375 {
1382 }
1383 }
1387 /* Convert -((double)float) into (double)(-float). */
1389 {
1393 }
1397 /* Negate -f(x) as f(-x). */
1400 {
1406 }
1410 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1412 {
1417 {
1424 }
1425 }
1430 }
1433 }
1435 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1436 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1437 return NULL_TREE. */
1439 static tree
1441 {
1454 }
1455 \f
1456 /* Split a tree IN into a constant, literal and variable parts that could be
1457 combined with CODE to make IN. "constant" means an expression with
1458 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1459 commutative arithmetic operation. Store the constant part into *CONP,
1460 the literal in *LITP and return the variable part. If a part isn't
1461 present, set it to null. If the tree does not decompose in this way,
1462 return the entire tree as the variable part and the other parts as null.
1464 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1465 case, we negate an operand that was subtracted. Except if it is a
1466 literal for which we use *MINUS_LITP instead.
1468 If NEGATE_P is true, we are negating all of IN, again except a literal
1469 for which we use *MINUS_LITP instead.
1471 If IN is itself a literal or constant, return it as appropriate.
1473 Note that we do not guarantee that any of the three values will be the
1474 same type as IN, but they will have the same signedness and mode. */
1476 static tree
1479 {
1486 /* Strip any conversions that don't change the machine mode or signedness. */
1495 /* We can associate addition and subtraction together (even
1496 though the C standard doesn't say so) for integers because
1497 the value is not affected. For reals, the value might be
1498 affected, so we can't. */
1501 {
1507 /* First see if either of the operands is a literal, then a constant. */
1520 /* If we haven't dealt with either operand, this is not a case we can
1521 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1526 else
1529 /* Now do any needed negations. */
1536 }
1539 else
1543 {
1550 }
1553 }
1555 /* Re-associate trees split by the above function. T1 and T2 are either
1556 expressions to associate or null. Return the new expression, if any. If
1557 we build an operation, do it in TYPE and with CODE. */
1559 static tree
1561 {
1567 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1568 try to fold this since we will have infinite recursion. But do
1569 deal with any NEGATE_EXPRs. */
1572 {
1574 {
1583 }
1585 {
1588 }
1592 }
1596 }
1597 \f
1598 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1599 for use in int_const_binop, size_binop and size_diffop. */
1601 static bool
1603 {
1610 {
1619 }
1624 }
1627 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1628 to produce a new constant. Return NULL_TREE if we don't know how
1629 to evaluate CODE at compile-time.
1631 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1633 tree
1635 {
1639 HOST_WIDE_INT hi;
1641 HOST_WIDE_INT garbageh;
1642 tree t;
1645 int is_sizetype
1655 {
1671 /* It's unclear from the C standard whether shifts can overflow.
1672 The following code ignores overflow; perhaps a C standard
1673 interpretation ruling is needed. */
1702 /* This is a shortcut for a common special case. */
1707 {
1713 }
1715 /* ... fall through ... */
1721 {
1724 }
1727 {
1730 }
1737 /* This is a shortcut for a common special case. */
1742 {
1747 }
1749 /* ... fall through ... */
1767 else
1773 else
1779 }
1782 {
1785 /* Propagate overflow flags ourselves. */
1788 {
1791 }
1792 }
1793 else
1799 }
1801 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1802 constant. We assume ARG1 and ARG2 have the same data type, or at least
1803 are the same kind of constant and the same machine mode. Return zero if
1804 combining the constants is not allowed in the current operating mode.
1806 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1808 static tree
1810 {
1811 /* Sanity check for the recursive cases. */
1822 {
1824 REAL_VALUE_TYPE d1;
1825 REAL_VALUE_TYPE d2;
1826 REAL_VALUE_TYPE value;
1827 REAL_VALUE_TYPE result;
1831 /* The following codes are handled by real_arithmetic. */
1833 {
1844 }
1852 /* Don't perform operation if we honor signaling NaNs and
1853 either operand is a NaN. */
1858 /* Don't perform operation if it would raise a division
1859 by zero exception. */
1865 /* If either operand is a NaN, just return it. Otherwise, set up
1866 for floating-point trap; we return an overflow. */
1875 /* Don't constant fold this floating point operation if
1876 the result has overflowed and flag_trapping_math. */
1884 /* Don't constant fold this floating point operation if the
1885 result may dependent upon the run-time rounding mode and
1886 flag_rounding_math is set, or if GCC's software emulation
1887 is unable to accurately represent the result. */
1897 }
1900 {
1901 FIXED_VALUE_TYPE f1;
1902 FIXED_VALUE_TYPE f2;
1903 FIXED_VALUE_TYPE result;
1908 /* The following codes are handled by fixed_arithmetic. */
1910 {
1927 }
1934 /* Propagate overflow flags. */
1938 }
1941 {
1950 {
1961 notrunc);
1965 notrunc);
1969 {
1970 tree magsquared
1974 notrunc);
1975 tree t1
1979 notrunc);
1980 tree t2
1984 notrunc);
1991 }
1996 }
2000 }
2003 {
2015 {
2018 /* The trailing elements can be empty and should be treated as 0 */
2021 else
2022 {
2025 }
2029 else
2030 {
2033 }
2037 /* It is possible that const_binop cannot handle the given
2038 code and return NULL_TREE */
2043 }
2045 }
2047 }
2049 /* Create a size type INT_CST node with NUMBER sign extended. KIND
2050 indicates which particular sizetype to create. */
2052 tree
2054 {
2056 }
2057 \f
2058 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
2059 is a tree code. The type of the result is taken from the operands.
2060 Both must be equivalent integer types, ala int_binop_types_match_p.
2061 If the operands are constant, so is the result. */
2063 tree
2065 {
2074 /* Handle the special case of two integer constants faster. */
2076 {
2077 /* And some specific cases even faster than that. */
2079 {
2084 }
2086 {
2089 }
2091 {
2094 }
2096 /* Handle general case of two integer constants. */
2098 }
2101 }
2103 /* Given two values, either both of sizetype or both of bitsizetype,
2104 compute the difference between the two values. Return the value
2105 in signed type corresponding to the type of the operands. */
2107 tree
2109 {
2111 tree ctype;
2116 /* If the type is already signed, just do the simple thing. */
2124 else
2127 /* If either operand is not a constant, do the conversions to the signed
2128 type and subtract. The hardware will do the right thing with any
2129 overflow in the subtraction. */
2134 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2135 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2136 overflow) and negate (which can't either). Special-case a result
2137 of zero while we're here. */
2142 else
2146 }
2147 \f
2148 /* A subroutine of fold_convert_const handling conversions of an
2149 INTEGER_CST to another integer type. */
2151 static tree
2153 {
2154 tree t;
2156 /* Given an integer constant, make new constant with new type,
2157 appropriately sign-extended or truncated. */
2160 /* Don't set the overflow when
2161 converting from a pointer, */
2163 /* or to a sizetype with same signedness
2164 and the precision is unchanged.
2165 ??? sizetype is always sign-extended,
2166 but its signedness depends on the
2167 frontend. Thus we see spurious overflows
2168 here if we do not check this. */
2183 }
2185 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2186 to an integer type. */
2188 static tree
2190 {
2192 tree t;
2194 /* The following code implements the floating point to integer
2195 conversion rules required by the Java Language Specification,
2196 that IEEE NaNs are mapped to zero and values that overflow
2197 the target precision saturate, i.e. values greater than
2198 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2199 are mapped to INT_MIN. These semantics are allowed by the
2200 C and C++ standards that simply state that the behavior of
2201 FP-to-integer conversion is unspecified upon overflow. */
2204 REAL_VALUE_TYPE r;
2208 {
2215 }
2217 /* If R is NaN, return zero and show we have an overflow. */
2219 {
2223 }
2225 /* See if R is less than the lower bound or greater than the
2226 upper bound. */
2229 {
2233 {
2237 }
2238 }
2241 {
2244 {
2247 {
2251 }
2252 }
2253 }
2261 }
2263 /* A subroutine of fold_convert_const handling conversions of a
2264 FIXED_CST to an integer type. */
2266 static tree
2268 {
2269 tree t;
2273 /* Right shift FIXED_CST to temp by fbit. */
2277 {
2282 /* Left shift temp to temp_trunc by fbit. */
2287 }
2288 else
2289 {
2294 }
2296 /* If FIXED_CST is negative, we need to round the value toward 0.
2297 By checking if the fractional bits are not zero to add 1 to temp. */
2300 {
2301 double_int one;
2305 }
2307 /* Given a fixed-point constant, make new constant with new type,
2308 appropriately sign-extended or truncated. */
2316 }
2318 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2319 to another floating point type. */
2321 static tree
2323 {
2324 REAL_VALUE_TYPE value;
2325 tree t;
2332 }
2334 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2335 to a floating point type. */
2337 static tree
2339 {
2340 REAL_VALUE_TYPE value;
2341 tree t;
2348 }
2350 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2351 to another fixed-point type. */
2353 static tree
2355 {
2356 FIXED_VALUE_TYPE value;
2357 tree t;
2364 /* Propagate overflow flags. */
2368 }
2370 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2371 to a fixed-point type. */
2373 static tree
2375 {
2376 FIXED_VALUE_TYPE value;
2377 tree t;
2386 /* Propagate overflow flags. */
2390 }
2392 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2393 to a fixed-point type. */
2395 static tree
2397 {
2398 FIXED_VALUE_TYPE value;
2399 tree t;
2407 /* Propagate overflow flags. */
2411 }
2413 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2414 type TYPE. If no simplification can be done return NULL_TREE. */
2416 static tree
2418 {
2424 {
2431 }
2433 {
2440 }
2442 {
2449 }
2451 }
2453 /* Construct a vector of zero elements of vector type TYPE. */
2455 static tree
2457 {
2468 }
2470 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2472 bool
2474 {
2489 {
2508 }
2509 }
2511 /* Convert expression ARG to type TYPE. Used by the middle-end for
2512 simple conversions in preference to calling the front-end's convert. */
2514 tree
2516 {
2518 tree tem;
2532 {
2537 {
2541 }
2546 {
2549 }
2556 {
2560 }
2562 {
2566 }
2568 {
2572 }
2575 {
2593 }
2598 {
2602 }
2605 {
2619 }
2623 {
2633 {
2637 {
2641 }
2649 }
2653 }
2671 }
2672 }
2673 \f
2674 /* Return false if expr can be assumed not to be an lvalue, true
2675 otherwise. */
2677 static bool
2679 {
2680 /* We only need to wrap lvalue tree codes. */
2682 {
2716 /* Assume the worst for front-end tree codes. */
2720 }
2723 }
2725 /* Return an expr equal to X but certainly not valid as an lvalue. */
2727 tree
2729 {
2730 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2731 us. */
2738 }
2740 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2741 Zero means allow extended lvalues. */
2745 /* When pedantic, return an expr equal to X but certainly not valid as a
2746 pedantic lvalue. Otherwise, return X. */
2748 static tree
2750 {
2753 else
2755 }
2756 \f
2757 /* Given a tree comparison code, return the code that is the logical inverse
2758 of the given code. It is not safe to do this for floating-point
2759 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2760 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2762 enum tree_code
2764 {
2769 {
2800 }
2801 }
2803 /* Similar, but return the comparison that results if the operands are
2804 swapped. This is safe for floating-point. */
2806 enum tree_code
2808 {
2810 {
2836 }
2837 }
2840 /* Convert a comparison tree code from an enum tree_code representation
2841 into a compcode bit-based encoding. This function is the inverse of
2842 compcode_to_comparison. */
2844 static enum comparison_code
2846 {
2848 {
2879 }
2880 }
2882 /* Convert a compcode bit-based encoding of a comparison operator back
2883 to GCC's enum tree_code representation. This function is the
2884 inverse of comparison_to_compcode. */
2886 static enum tree_code
2888 {
2890 {
2921 }
2922 }
2924 /* Return a tree for the comparison which is the combination of
2925 doing the AND or OR (depending on CODE) of the two operations LCODE
2926 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2927 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2928 if this makes the transformation invalid. */
2930 tree
2934 {
2941 {
2952 }
2955 {
2956 /* Eliminate unordered comparisons, as well as LTGT and ORD
2957 which are not used unless the mode has NaNs. */
2963 }
2965 {
2966 /* Check that the original operation and the optimized ones will trap
2967 under the same condition. */
2978 /* In a short-circuited boolean expression the LHS might be
2979 such that the RHS, if evaluated, will never trap. For
2980 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2981 if neither x nor y is NaN. (This is a mixed blessing: for
2982 example, the expression above will never trap, hence
2983 optimizing it to x < y would be invalid). */
2988 /* If the comparison was short-circuited, and only the RHS
2989 trapped, we may now generate a spurious trap. */
2994 /* If we changed the conditions that cause a trap, we lose. */
2997 }
3003 else
3006 }
3007 \f
3008 /* Return nonzero if two operands (typically of the same tree node)
3009 are necessarily equal. If either argument has side-effects this
3010 function returns zero. FLAGS modifies behavior as follows:
3012 If OEP_ONLY_CONST is set, only return nonzero for constants.
3013 This function tests whether the operands are indistinguishable;
3014 it does not test whether they are equal using C's == operation.
3015 The distinction is important for IEEE floating point, because
3016 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
3017 (2) two NaNs may be indistinguishable, but NaN!=NaN.
3019 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
3020 even though it may hold multiple values during a function.
3021 This is because a GCC tree node guarantees that nothing else is
3022 executed between the evaluation of its "operands" (which may often
3023 be evaluated in arbitrary order). Hence if the operands themselves
3024 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
3025 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
3026 unset means assuming isochronic (or instantaneous) tree equivalence.
3027 Unless comparing arbitrary expression trees, such as from different
3028 statements, this flag can usually be left unset.
3030 If OEP_PURE_SAME is set, then pure functions with identical arguments
3031 are considered the same. It is used when the caller has other ways
3032 to ensure that global memory is unchanged in between. */
3034 int
3036 {
3037 /* If either is ERROR_MARK, they aren't equal. */
3041 /* Check equality of integer constants before bailing out due to
3042 precision differences. */
3046 /* If both types don't have the same signedness, then we can't consider
3047 them equal. We must check this before the STRIP_NOPS calls
3048 because they may change the signedness of the arguments. As pointers
3049 strictly don't have a signedness, require either two pointers or
3050 two non-pointers as well. */
3055 /* If both types don't have the same precision, then it is not safe
3056 to strip NOPs. */
3063 /* In case both args are comparisons but with different comparison
3064 code, try to swap the comparison operands of one arg to produce
3065 a match and compare that variant. */
3069 {
3077 }
3080 /* This is needed for conversions and for COMPONENT_REF.
3081 Might as well play it safe and always test this. */
3087 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3088 We don't care about side effects in that case because the SAVE_EXPR
3089 takes care of that for us. In all other cases, two expressions are
3090 equal if they have no side effects. If we have two identical
3091 expressions with side effects that should be treated the same due
3092 to the only side effects being identical SAVE_EXPR's, that will
3093 be detected in the recursive calls below. */
3099 /* Next handle constant cases, those for which we can return 1 even
3100 if ONLY_CONST is set. */
3103 {
3118 {
3119 /* If we do not distinguish between signed and unsigned zero,
3120 consider them equal. */
3123 }
3127 {
3133 {
3135 flags))
3139 }
3142 }
3146 flags)
3148 flags));
3161 }
3166 /* Define macros to test an operand from arg0 and arg1 for equality and a
3167 variant that allows null and views null as being different from any
3168 non-null value. In the latter case, if either is null, the both
3169 must be; otherwise, do the normal comparison. */
3170 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3171 TREE_OPERAND (arg1, N), flags)
3173 #define OP_SAME_WITH_NULL(N) \
3174 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3175 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3178 {
3180 /* Two conversions are equal only if signedness and modes match. */
3182 {
3183 CASE_CONVERT:
3191 }
3201 /* For commutative ops, allow the other order. */
3209 /* If either of the pointer (or reference) expressions we are
3210 dereferencing contain a side effect, these cannot be equal. */
3216 {
3226 /* Operands 2 and 3 may be null.
3227 Compare the array index by value if it is constant first as we
3228 may have different types but same value here. */
3237 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3238 may be NULL when we're called to compare MEM_EXPRs. */
3248 }
3252 {
3267 /* Otherwise take into account this is a commutative operation. */
3278 }
3282 {
3284 /* If the CALL_EXPRs call different functions, then they
3285 clearly can not be equal. */
3287 flags))
3290 {
3294 else
3298 }
3300 /* Now see if all the arguments are the same. */
3301 {
3312 /* If we get here and both argument lists are exhausted
3313 then the CALL_EXPRs are equal. */
3315 }
3318 }
3321 /* Consider __builtin_sqrt equal to sqrt. */
3329 }
3331 #undef OP_SAME
3332 #undef OP_SAME_WITH_NULL
3333 }
3334 \f
3335 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3336 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3338 When in doubt, return 0. */
3340 static int
3342 {
3354 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3355 and see if the inner values are the same. This removes any
3356 signedness comparison, which doesn't matter here. */
3363 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3364 actual comparison operand, ARG0.
3366 First throw away any conversions to wider types
3367 already present in the operands. */
3376 {
3379 /* Make sure shorter operand is extended the right way
3380 to match the longer operand. */
3386 }
3389 }
3390 \f
3391 /* See if ARG is an expression that is either a comparison or is performing
3392 arithmetic on comparisons. The comparisons must only be comparing
3393 two different values, which will be stored in *CVAL1 and *CVAL2; if
3394 they are nonzero it means that some operands have already been found.
3395 No variables may be used anywhere else in the expression except in the
3396 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3397 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3399 If this is true, return 1. Otherwise, return zero. */
3401 static int
3403 {
3407 /* We can handle some of the tcc_expression cases here. */
3417 {
3418 /* If we've already found a CVAL1 or CVAL2, this expression is
3419 two complex to handle. */
3425 }
3428 {
3451 /* First see if we can handle the first operand, then the second. For
3452 the second operand, we know *CVAL1 can't be zero. It must be that
3453 one side of the comparison is each of the values; test for the
3454 case where this isn't true by failing if the two operands
3455 are the same. */
3464 ;
3468 ;
3469 else
3473 ;
3477 ;
3478 else
3485 }
3486 }
3487 \f
3488 /* ARG is a tree that is known to contain just arithmetic operations and
3489 comparisons. Evaluate the operations in the tree substituting NEW0 for
3490 any occurrence of OLD0 as an operand of a comparison and likewise for
3491 NEW1 and OLD1. */
3493 static tree
3495 {
3500 /* We can handle some of the tcc_expression cases here. */
3508 {
3523 {
3540 }
3541 /* Fall through - ??? */
3544 {
3548 /* We need to check both for exact equality and tree equality. The
3549 former will be true if the operand has a side-effect. In that
3550 case, we know the operand occurred exactly once. */
3563 }
3567 }
3568 }
3569 \f
3570 /* Return a tree for the case when the result of an expression is RESULT
3571 converted to TYPE and OMITTED was previously an operand of the expression
3572 but is now not needed (e.g., we folded OMITTED * 0).
3574 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3575 the conversion of RESULT to TYPE. */
3577 tree
3579 {
3582 /* If the resulting operand is an empty statement, just return the omitted
3583 statement casted to void. */
3591 }
3593 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3595 static tree
3597 {
3600 /* If the resulting operand is an empty statement, just return the omitted
3601 statement casted to void. */
3609 }
3611 /* Return a tree for the case when the result of an expression is RESULT
3612 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3613 of the expression but are now not needed.
3615 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3616 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3617 evaluated before OMITTED2. Otherwise, if neither has side effects,
3618 just do the conversion of RESULT to TYPE. */
3620 tree
3622 {
3631 }
3633 \f
3634 /* Return a simplified tree node for the truth-negation of ARG. This
3635 never alters ARG itself. We assume that ARG is an operation that
3636 returns a truth value (0 or 1).
3638 FIXME: one would think we would fold the result, but it causes
3639 problems with the dominator optimizer. */
3641 tree
3643 {
3647 /* If this is a comparison, we can simply invert it, except for
3648 floating-point non-equality comparisons, in which case we just
3649 enclose a TRUTH_NOT_EXPR around what we have. */
3652 {
3655 && flag_trapping_math
3659 else
3660 {
3665 else
3668 }
3669 }
3672 {
3687 /* Here we can invert either operand. We invert the first operand
3688 unless the second operand is a TRUTH_NOT_EXPR in which case our
3689 result is the XOR of the first operand with the inside of the
3690 negation of the second operand. */
3695 else
3714 {
3717 /* A COND_EXPR may have a throw as one operand, which
3718 then has void type. Just leave void operands
3719 as they are. */
3725 }
3758 }
3761 }
3763 /* Return a simplified tree node for the truth-negation of ARG. This
3764 never alters ARG itself. We assume that ARG is an operation that
3765 returns a truth value (0 or 1).
3767 FIXME: one would think we would fold the result, but it causes
3768 problems with the dominator optimizer. */
3770 tree
3772 {
3773 tree tem;
3783 }
3785 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3786 operands are another bit-wise operation with a common input. If so,
3787 distribute the bit operations to save an operation and possibly two if
3788 constants are involved. For example, convert
3789 (A | B) & (A | C) into A | (B & C)
3790 Further simplification will occur if B and C are constants.
3792 If this optimization cannot be done, 0 will be returned. */
3794 static tree
3796 {
3797 tree common;
3807 {
3811 }
3813 {
3817 }
3819 {
3823 }
3825 {
3829 }
3830 else
3838 }
3840 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3841 with code CODE. This optimization is unsafe. */
3842 static tree
3844 {
3848 /* (A / C) +- (B / C) -> (A +- B) / C. */
3858 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3863 {
3875 }
3878 }
3879 \f
3880 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3881 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3883 static tree
3886 {
3890 {
3897 }
3911 }
3913 /* Optimize a bit-field compare.
3915 There are two cases: First is a compare against a constant and the
3916 second is a comparison of two items where the fields are at the same
3917 bit position relative to the start of a chunk (byte, halfword, word)
3918 large enough to contain it. In these cases we can avoid the shift
3919 implicit in bitfield extractions.
3921 For constants, we emit a compare of the shifted constant with the
3922 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3923 compared. For two fields at the same position, we do the ANDs with the
3924 similar mask and compare the result of the ANDs.
3926 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3927 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3928 are the left and right operands of the comparison, respectively.
3930 If the optimization described above can be done, we return the resulting
3931 tree. Otherwise we return zero. */
3933 static tree
3936 {
3945 tree mask;
3946 tree offset;
3948 /* Get all the information about the extractions being done. If the bit size
3949 if the same as the size of the underlying object, we aren't doing an
3950 extraction at all and so can do nothing. We also don't want to
3951 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3952 then will no longer be able to replace it. */
3960 {
3961 /* If this is not a constant, we can only do something if bit positions,
3962 sizes, and signedness are the same. */
3970 }
3972 /* See if we can find a mode to refer to this field. We should be able to,
3973 but fail if we can't. */
3982 /* Set signed and unsigned types of the precision of this mode for the
3983 shifts below. */
3987 /* Compute the bit position and size for the new reference and our offset
3988 within it. If the new reference is the same size as the original, we
3989 won't optimize anything, so return zero. */
3999 /* Make the mask to be used against the extracted field. */
4006 /* If not comparing with constant, just rework the comparison
4007 and return. */
4011 unsigned_type,
4014 mask),
4017 unsigned_type,
4020 mask));
4022 /* Otherwise, we are handling the constant case. See if the constant is too
4023 big for the field. Warn and return a tree of for 0 (false) if so. We do
4024 this not only for its own sake, but to avoid having to test for this
4025 error case below. If we didn't, we might generate wrong code.
4027 For unsigned fields, the constant shifted right by the field length should
4028 be all zero. For signed fields, the high-order bits should agree with
4029 the sign bit. */
4032 {
4036 {
4040 }
4041 }
4042 else
4043 {
4047 {
4051 }
4052 }
4054 /* Single-bit compares should always be against zero. */
4056 {
4059 }
4061 /* Make a new bitfield reference, shift the constant over the
4062 appropriate number of bits and mask it with the computed mask
4063 (in case this was a signed field). If we changed it, make a new one. */
4066 {
4069 }
4079 rhs);
4080 }
4081 \f
4082 /* Subroutine for fold_truthop: decode a field reference.
4084 If EXP is a comparison reference, we return the innermost reference.
4086 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4087 set to the starting bit number.
4089 If the innermost field can be completely contained in a mode-sized
4090 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4092 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4093 otherwise it is not changed.
4095 *PUNSIGNEDP is set to the signedness of the field.
4097 *PMASK is set to the mask used. This is either contained in a
4098 BIT_AND_EXPR or derived from the width of the field.
4100 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4102 Return 0 if this is not a component reference or is one that we can't
4103 do anything with. */
4105 static tree
4110 {
4114 tree unsigned_type;
4117 /* All the optimizations using this function assume integer fields.
4118 There are problems with FP fields since the type_for_size call
4119 below can fail for, e.g., XFmode. */
4123 /* We are interested in the bare arrangement of bits, so strip everything
4124 that doesn't affect the machine mode. However, record the type of the
4125 outermost expression if it may matter below. */
4132 {
4138 }
4147 /* If the number of bits in the reference is the same as the bitsize of
4148 the outer type, then the outer type gives the signedness. Otherwise
4149 (in case of a small bitfield) the signedness is unchanged. */
4153 /* Compute the mask to access the bitfield. */
4162 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4170 }
4172 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4173 bit positions. */
4175 static int
4177 {
4180 tree tmask;
4184 return
4191 }
4193 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4194 represents the sign bit of EXP's type. If EXP represents a sign
4195 or zero extension, also test VAL against the unextended type.
4196 The return value is the (sub)expression whose sign bit is VAL,
4197 or NULL_TREE otherwise. */
4199 static tree
4201 {
4205 tree t;
4207 /* Tree EXP must have an integral type. */
4212 /* Tree VAL must be an integer constant. */
4219 {
4226 }
4227 else
4228 {
4235 }
4237 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
4238 treat VAL as if it were unsigned. */
4243 /* Handle extension from a narrower type. */
4249 }
4251 /* Subroutine for fold_truthop: determine if an operand is simple enough
4252 to be evaluated unconditionally. */
4254 static int
4256 {
4257 /* Strip any conversions that don't change the machine mode. */
4266 /* Don't regard global variables as simple. They may be
4267 allocated in ways unknown to the compiler (shared memory,
4268 #pragma weak, etc). */
4271 /* Loading a static variable is unduly expensive, but global
4272 registers aren't expensive. */
4274 }
4275 \f
4276 /* The following functions are subroutines to fold_range_test and allow it to
4277 try to change a logical combination of comparisons into a range test.
4279 For example, both
4280 X == 2 || X == 3 || X == 4 || X == 5
4281 and
4282 X >= 2 && X <= 5
4283 are converted to
4284 (unsigned) (X - 2) <= 3
4286 We describe each set of comparisons as being either inside or outside
4287 a range, using a variable named like IN_P, and then describe the
4288 range with a lower and upper bound. If one of the bounds is omitted,
4289 it represents either the highest or lowest value of the type.
4291 In the comments below, we represent a range by two numbers in brackets
4292 preceded by a "+" to designate being inside that range, or a "-" to
4293 designate being outside that range, so the condition can be inverted by
4294 flipping the prefix. An omitted bound is represented by a "-". For
4295 example, "- [-, 10]" means being outside the range starting at the lowest
4296 possible value and ending at 10, in other words, being greater than 10.
4297 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4298 always false.
4300 We set up things so that the missing bounds are handled in a consistent
4301 manner so neither a missing bound nor "true" and "false" need to be
4302 handled using a special case. */
4304 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4305 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4306 and UPPER1_P are nonzero if the respective argument is an upper bound
4307 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4308 must be specified for a comparison. ARG1 will be converted to ARG0's
4309 type if both are specified. */
4311 static tree
4314 {
4315 tree tem;
4319 /* If neither arg represents infinity, do the normal operation.
4320 Else, if not a comparison, return infinity. Else handle the special
4321 comparison rules. Note that most of the cases below won't occur, but
4322 are handled for consistency. */
4325 {
4330 }
4335 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4336 for neither. In real maths, we cannot assume open ended ranges are
4337 the same. But, this is computer arithmetic, where numbers are finite.
4338 We can therefore make the transformation of any unbounded range with
4339 the value Z, Z being greater than any representable number. This permits
4340 us to treat unbounded ranges as equal. */
4344 {
4365 }
4368 }
4369 \f
4370 /* Given EXP, a logical expression, set the range it is testing into
4371 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4372 actually being tested. *PLOW and *PHIGH will be made of the same
4373 type as the returned expression. If EXP is not a comparison, we
4374 will most likely not be returning a useful value and range. Set
4375 *STRICT_OVERFLOW_P to true if the return value is only valid
4376 because signed overflow is undefined; otherwise, do not change
4377 *STRICT_OVERFLOW_P. */
4379 static tree
4382 {
4389 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4390 and see if we can refine the range. Some of the cases below may not
4391 happen, but it doesn't seem worth worrying about this. We "continue"
4392 the outer loop when we've changed something; otherwise we "break"
4393 the switch, which will "break" the while. */
4399 {
4404 {
4416 }
4419 {
4426 /* We can only do something if the range is testing for zero
4427 and if the second operand is an integer constant. Note that
4428 saying something is "in" the range we make is done by
4429 complementing IN_P since it will set in the initial case of
4430 being not equal to zero; "out" is leaving it alone. */
4437 {
4458 }
4460 /* If this is an unsigned comparison, we also know that EXP is
4461 greater than or equal to zero. We base the range tests we make
4462 on that fact, so we record it here so we can parse existing
4463 range tests. We test arg0_type since often the return type
4464 of, e.g. EQ_EXPR, is boolean. */
4466 {
4470 NULL_TREE))
4475 /* If the high bound is missing, but we have a nonzero low
4476 bound, reverse the range so it goes from zero to the low bound
4477 minus 1. */
4479 {
4484 }
4485 }
4491 /* (-x) IN [a,b] -> x in [-b, -a] */
4503 /* ~ X -> -X - 1 */
4512 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4513 move a constant to the other side. */
4518 /* If EXP is signed, any overflow in the computation is undefined,
4519 so we don't worry about it so long as our computations on
4520 the bounds don't overflow. For unsigned, overflow is defined
4521 and this is exactly the right thing. */
4533 /* Check for an unsigned range which has wrapped around the maximum
4534 value thus making n_high < n_low, and normalize it. */
4536 {
4542 /* If the range is of the form +/- [ x+1, x ], we won't
4543 be able to normalize it. But then, it represents the
4544 whole range or the empty set, so make it
4545 +/- [ -, - ]. */
4549 else
4551 }
4552 else
4576 /* If we're converting arg0 from an unsigned type, to exp,
4577 a signed type, we will be doing the comparison as unsigned.
4578 The tests above have already verified that LOW and HIGH
4579 are both positive.
4581 So we have to ensure that we will handle large unsigned
4582 values the same way that the current signed bounds treat
4583 negative values. */
4586 {
4587 tree high_positive;
4588 tree equiv_type;
4589 /* For fixed-point modes, we need to pass the saturating flag
4590 as the 2nd parameter. */
4595 else
4599 /* A range without an upper bound is, naturally, unbounded.
4600 Since convert would have cropped a very large value, use
4601 the max value for the destination type. */
4602 high_positive
4609 high_positive),
4612 /* If the low bound is specified, "and" the range with the
4613 range for which the original unsigned value will be
4614 positive. */
4616 {
4620 integer_zero_node),
4621 high_positive))
4625 }
4626 else
4627 {
4628 /* Otherwise, "or" the range with the range of the input
4629 that will be interpreted as negative. */
4633 integer_zero_node),
4634 high_positive))
4638 }
4639 }
4647 }
4650 }
4652 /* If EXP is a constant, we can evaluate whether this is true or false. */
4654 {
4661 }
4665 }
4666 \f
4667 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4668 type, TYPE, return an expression to test if EXP is in (or out of, depending
4669 on IN_P) the range. Return 0 if the test couldn't be created. */
4671 static tree
4673 {
4675 tree value;
4677 #ifdef HAVE_canonicalize_funcptr_for_compare
4678 /* Disable this optimization for function pointer expressions
4679 on targets that require function pointer canonicalization. */
4684 #endif
4687 {
4693 }
4711 {
4713 {
4717 }
4719 }
4721 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4723 {
4725 HOST_WIDE_INT hi;
4730 {
4733 }
4734 else
4735 {
4738 }
4741 {
4743 {
4746 etype
4748 else
4751 }
4754 }
4755 }
4757 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4758 This requires wrap-around arithmetics for the type of the expression. */
4760 {
4762 /* There is no requirement that LOW be within the range of ETYPE
4763 if the latter is a subtype. It must, however, be within the base
4764 type of ETYPE. So be sure we do the subtraction in that type. */
4777 }
4779 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4782 {
4785 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4786 for the type in question, as we rely on this here. */
4796 else
4798 }
4808 {
4810 {
4816 }
4818 }
4826 }
4827 \f
4828 /* Return the predecessor of VAL in its type, handling the infinite case. */
4830 static tree
4832 {
4838 else
4840 }
4842 /* Return the successor of VAL in its type, handling the infinite case. */
4844 static tree
4846 {
4852 else
4854 }
4856 /* Given two ranges, see if we can merge them into one. Return 1 if we
4857 can, 0 if we can't. Set the output range into the specified parameters. */
4859 static int
4862 {
4866 tree tem;
4876 /* Make range 0 be the range that starts first, or ends last if they
4877 start at the same value. Swap them if it isn't. */
4880 || (lowequal
4883 {
4887 }
4889 /* Now flag two cases, whether the ranges are disjoint or whether the
4890 second range is totally subsumed in the first. Note that the tests
4891 below are simplified by the ones above. */
4897 /* We now have four cases, depending on whether we are including or
4898 excluding the two ranges. */
4900 {
4901 /* If they don't overlap, the result is false. If the second range
4902 is a subset it is the result. Otherwise, the range is from the start
4903 of the second to the end of the first. */
4908 else
4910 }
4913 {
4914 /* If they don't overlap, the result is the first range. If they are
4915 equal, the result is false. If the second range is a subset of the
4916 first, and the ranges begin at the same place, we go from just after
4917 the end of the second range to the end of the first. If the second
4918 range is not a subset of the first, or if it is a subset and both
4919 ranges end at the same place, the range starts at the start of the
4920 first range and ends just before the second range.
4921 Otherwise, we can't describe this as a single range. */
4927 {
4932 {
4933 /* We are in the weird situation where high0 > high1 but
4934 high1 has no successor. Punt. */
4936 }
4937 }
4939 {
4944 {
4945 /* low0 < low1 but low1 has no predecessor. Punt. */
4947 }
4948 }
4949 else
4951 }
4954 {
4955 /* If they don't overlap, the result is the second range. If the second
4956 is a subset of the first, the result is false. Otherwise,
4957 the range starts just after the first range and ends at the
4958 end of the second. */
4963 else
4964 {
4969 {
4970 /* high1 > high0 but high0 has no successor. Punt. */
4972 }
4973 }
4974 }
4976 else
4977 {
4978 /* The case where we are excluding both ranges. Here the complex case
4979 is if they don't overlap. In that case, the only time we have a
4980 range is if they are adjacent. If the second is a subset of the
4981 first, the result is the first. Otherwise, the range to exclude
4982 starts at the beginning of the first range and ends at the end of the
4983 second. */
4985 {
4990 else
4991 {
4992 /* Canonicalize - [min, x] into - [-, x]. */
4995 {
5000 /* FALLTHROUGH */
5013 }
5015 /* Canonicalize - [x, max] into - [x, -]. */
5018 {
5023 /* FALLTHROUGH */
5038 }
5040 /* The ranges might be also adjacent between the maximum and
5041 minimum values of the given type. For
5042 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5043 return + [x + 1, y - 1]. */
5045 {
5052 }
5053 else
5055 }
5056 }
5059 else
5061 }
5065 }
5066 \f
5068 /* Subroutine of fold, looking inside expressions of the form
5069 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5070 of the COND_EXPR. This function is being used also to optimize
5071 A op B ? C : A, by reversing the comparison first.
5073 Return a folded expression whose code is not a COND_EXPR
5074 anymore, or NULL_TREE if no folding opportunity is found. */
5076 static tree
5078 {
5083 tree tem;
5088 /* If we have A op 0 ? A : -A, consider applying the following
5089 transformations:
5091 A == 0? A : -A same as -A
5092 A != 0? A : -A same as A
5093 A >= 0? A : -A same as abs (A)
5094 A > 0? A : -A same as abs (A)
5095 A <= 0? A : -A same as -abs (A)
5096 A < 0? A : -A same as -abs (A)
5098 None of these transformations work for modes with signed
5099 zeros. If A is +/-0, the first two transformations will
5100 change the sign of the result (from +0 to -0, or vice
5101 versa). The last four will fix the sign of the result,
5102 even though the original expressions could be positive or
5103 negative, depending on the sign of A.
5105 Note that all these transformations are correct if A is
5106 NaN, since the two alternatives (A and -A) are also NaNs. */
5113 /* In the case that A is of the form X-Y, '-A' (arg2) may
5114 have already been folded to Y-X, check for that. */
5122 {
5134 /* Fall through. */
5156 }
5158 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5159 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5160 both transformations are correct when A is NaN: A != 0
5161 is then true, and A == 0 is false. */
5165 {
5170 }
5172 /* Try some transformations of A op B ? A : B.
5174 A == B? A : B same as B
5175 A != B? A : B same as A
5176 A >= B? A : B same as max (A, B)
5177 A > B? A : B same as max (B, A)
5178 A <= B? A : B same as min (A, B)
5179 A < B? A : B same as min (B, A)
5181 As above, these transformations don't work in the presence
5182 of signed zeros. For example, if A and B are zeros of
5183 opposite sign, the first two transformations will change
5184 the sign of the result. In the last four, the original
5185 expressions give different results for (A=+0, B=-0) and
5186 (A=-0, B=+0), but the transformed expressions do not.
5188 The first two transformations are correct if either A or B
5189 is a NaN. In the first transformation, the condition will
5190 be false, and B will indeed be chosen. In the case of the
5191 second transformation, the condition A != B will be true,
5192 and A will be chosen.
5194 The conversions to max() and min() are not correct if B is
5195 a number and A is not. The conditions in the original
5196 expressions will be false, so all four give B. The min()
5197 and max() versions would give a NaN instead. */
5200 /* Avoid these transformations if the COND_EXPR may be used
5201 as an lvalue in the C++ front-end. PR c++/19199. */
5202 && (in_gimple_form
5207 {
5212 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5214 {
5218 }
5221 {
5230 /* In C++ a ?: expression can be an lvalue, so put the
5231 operand which will be used if they are equal first
5232 so that we can convert this back to the
5233 corresponding COND_EXPR. */
5235 {
5242 }
5249 {
5256 }
5269 }
5270 }
5272 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5273 we might still be able to simplify this. For example,
5274 if C1 is one less or one more than C2, this might have started
5275 out as a MIN or MAX and been transformed by this function.
5276 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5282 {
5284 /* We can replace A with C1 in this case. */
5289 /* If C1 is C2 + 1, this is min(A, C2). */
5291 OEP_ONLY_CONST)
5295 OEP_ONLY_CONST))
5297 type,
5299 arg2));
5303 /* If C1 is C2 - 1, this is min(A, C2). */
5305 OEP_ONLY_CONST)
5309 OEP_ONLY_CONST))
5311 type,
5313 arg2));
5317 /* If C1 is C2 - 1, this is max(A, C2). */
5319 OEP_ONLY_CONST)
5323 OEP_ONLY_CONST))
5325 type,
5327 arg2));
5331 /* If C1 is C2 + 1, this is max(A, C2). */
5333 OEP_ONLY_CONST)
5337 OEP_ONLY_CONST))
5339 type,
5341 arg2));
5347 }
5350 }
5353 \f
5354 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5355 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5356 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5357 false) >= 2)
5358 #endif
5360 /* EXP is some logical combination of boolean tests. See if we can
5361 merge it into some range test. Return the new tree if so. */
5363 static tree
5365 {
5373 tree tem;
5377 /* If this is an OR operation, invert both sides; we will invert
5378 again at the end. */
5382 /* If both expressions are the same, if we can merge the ranges, and we
5383 can build the range test, return it or it inverted. If one of the
5384 ranges is always true or always false, consider it to be the same
5385 expression as the other. */
5393 {
5397 }
5399 /* On machines where the branch cost is expensive, if this is a
5400 short-circuited branch and the underlying object on both sides
5401 is the same, make a non-short-circuit operation. */
5407 {
5408 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5409 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5410 which cases we can't do this. */
5418 {
5427 {
5430 WARN_STRICT_OVERFLOW_COMPARISON);
5434 }
5435 }
5436 }
5439 }
5440 \f
5441 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5442 bit value. Arrange things so the extra bits will be set to zero if and
5443 only if C is signed-extended to its full width. If MASK is nonzero,
5444 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5446 static tree
5448 {
5451 tree temp;
5456 /* We work by getting just the sign bit into the low-order bit, then
5457 into the high-order bit, then sign-extend. We then XOR that value
5458 with C. */
5462 /* We must use a signed type in order to get an arithmetic right shift.
5463 However, we must also avoid introducing accidental overflows, so that
5464 a subsequent call to integer_zerop will work. Hence we must
5465 do the type conversion here. At this point, the constant is either
5466 zero or one, and the conversion to a signed type can never overflow.
5467 We could get an overflow if this conversion is done anywhere else. */
5476 /* If necessary, convert the type back to match the type of C. */
5481 }
5482 \f
5483 /* Find ways of folding logical expressions of LHS and RHS:
5484 Try to merge two comparisons to the same innermost item.
5485 Look for range tests like "ch >= '0' && ch <= '9'".
5486 Look for combinations of simple terms on machines with expensive branches
5487 and evaluate the RHS unconditionally.
5489 For example, if we have p->a == 2 && p->b == 4 and we can make an
5490 object large enough to span both A and B, we can do this with a comparison
5491 against the object ANDed with the a mask.
5493 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5494 operations to do this with one comparison.
5496 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5497 function and the one above.
5499 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5500 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5502 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5503 two operands.
5505 We return the simplified tree or 0 if no optimization is possible. */
5507 static tree
5509 {
5510 /* If this is the "or" of two comparisons, we can do something if
5511 the comparisons are NE_EXPR. If this is the "and", we can do something
5512 if the comparisons are EQ_EXPR. I.e.,
5513 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5515 WANTED_CODE is this operation code. For single bit fields, we can
5516 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5517 comparison for one-bit fields. */
5539 /* Start by getting the comparison codes. Fail if anything is volatile.
5540 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5541 it were surrounded with a NE_EXPR. */
5550 {
5554 }
5557 {
5561 }
5572 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5575 {
5576 tree result;
5579 {
5584 }
5587 {
5593 }
5594 }
5599 /* If the RHS can be evaluated unconditionally and its operands are
5600 simple, it wins to evaluate the RHS unconditionally on machines
5601 with expensive branches. In this case, this isn't a comparison
5602 that can be merged. Avoid doing this if the RHS is a floating-point
5603 comparison since those can trap. */
5610 {
5611 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5622 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5634 {
5638 }
5639 }
5641 /* See if the comparisons can be merged. Then get all the parameters for
5642 each side. */
5666 /* It must be true that the inner operation on the lhs of each
5667 comparison must be the same if we are to be able to do anything.
5668 Then see if we have constants. If not, the same must be true for
5669 the rhs's. */
5680 else
5683 /* If either comparison code is not correct for our logical operation,
5684 fail. However, we can convert a one-bit comparison against zero into
5685 the opposite comparison against that bit being set in the field. */
5689 {
5691 {
5692 /* Make the left operand unsigned, since we are only interested
5693 in the value of one bit. Otherwise we are doing the wrong
5694 thing below. */
5697 }
5698 else
5700 }
5702 /* This is analogous to the code for l_const above. */
5704 {
5706 {
5709 }
5710 else
5712 }
5714 /* See if we can find a mode that contains both fields being compared on
5715 the left. If we can't, fail. Otherwise, update all constants and masks
5716 to be relative to a field of that size. */
5721 volatilep);
5731 {
5734 }
5742 {
5750 {
5754 }
5755 }
5757 {
5765 {
5769 }
5770 }
5772 /* If the right sides are not constant, do the same for it. Also,
5773 disallow this optimization if a size or signedness mismatch occurs
5774 between the left and right sides. */
5776 {
5779 /* Make sure the two fields on the right
5780 correspond to the left without being swapped. */
5788 volatilep);
5798 {
5801 }
5808 /* Make a mask that corresponds to both fields being compared.
5809 Do this for both items being compared. If the operands are the
5810 same size and the bits being compared are in the same position
5811 then we can do this by masking both and comparing the masked
5812 results. */
5816 {
5828 }
5830 /* There is still another way we can do something: If both pairs of
5831 fields being compared are adjacent, we may be able to make a wider
5832 field containing them both.
5834 Note that we still must mask the lhs/rhs expressions. Furthermore,
5835 the mask must be shifted to account for the shift done by
5836 make_bit_field_ref. */
5841 {
5842 tree type;
5854 /* Convert to the smaller type before masking out unwanted bits. */
5857 {
5859 {
5863 }
5865 {
5869 }
5870 }
5879 }
5882 }
5884 /* Handle the case of comparisons with constants. If there is something in
5885 common between the masks, those bits of the constants must be the same.
5886 If not, the condition is always false. Test for this to avoid generating
5887 incorrect code below. */
5892 {
5894 {
5897 }
5898 else
5899 {
5902 }
5903 }
5905 /* Construct the expression we will return. First get the component
5906 reference we will make. Unless the mask is all ones the width of
5907 that field, perform the mask operation. Then compare with the
5908 merged constant. */
5918 }
5919 \f
5920 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5921 constant. */
5923 static tree
5925 {
5928 tree comp_const;
5929 tree minmax_const;
5931 tree inner;
5942 /* If something does not permit us to optimize, return the original tree. */
5950 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5951 and GT_EXPR, doing the rest with recursive calls using logical
5952 simplifications. */
5954 {
5956 {
5962 }
5965 return
5967 optimize_minmax_comparison
5969 optimize_minmax_comparison
5974 /* MAX (X, 0) == 0 -> X <= 0 */
5978 /* MAX (X, 0) == 5 -> X == 5 */
5982 /* MAX (X, 0) == -1 -> false */
5986 /* MIN (X, 0) == 0 -> X >= 0 */
5990 /* MIN (X, 0) == 5 -> false */
5993 else
5994 /* MIN (X, 0) == -1 -> X == -1 */
5999 /* MAX (X, 0) > 0 -> X > 0
6000 MAX (X, 0) > 5 -> X > 5 */
6004 /* MAX (X, 0) > -1 -> true */
6008 /* MIN (X, 0) > 0 -> false
6009 MIN (X, 0) > 5 -> false */
6012 else
6013 /* MIN (X, 0) > -1 -> X > -1 */
6018 }
6019 }
6020 \f
6021 /* T is an integer expression that is being multiplied, divided, or taken a
6022 modulus (CODE says which and what kind of divide or modulus) by a
6023 constant C. See if we can eliminate that operation by folding it with
6024 other operations already in T. WIDE_TYPE, if non-null, is a type that
6025 should be used for the computation if wider than our type.
6027 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6028 (X * 2) + (Y * 4). We must, however, be assured that either the original
6029 expression would not overflow or that overflow is undefined for the type
6030 in the language in question.
6032 If we return a non-null expression, it is an equivalent form of the
6033 original computation, but need not be in the original type.
6035 We set *STRICT_OVERFLOW_P to true if the return values depends on
6036 signed overflow being undefined. Otherwise we do not change
6037 *STRICT_OVERFLOW_P. */
6039 static tree
6042 {
6043 /* To avoid exponential search depth, refuse to allow recursion past
6044 three levels. Beyond that (1) it's highly unlikely that we'll find
6045 something interesting and (2) we've probably processed it before
6046 when we built the inner expression. */
6049 tree ret;
6054 depth++;
6056 depth--;
6059 }
6061 static tree
6064 {
6075 /* Don't deal with constants of zero here; they confuse the code below. */
6085 /* Note that we need not handle conditional operations here since fold
6086 already handles those cases. So just do arithmetic here. */
6088 {
6090 /* For a constant, we can always simplify if we are a multiply
6091 or (for divide and modulus) if it is a multiple of our constant. */
6099 /* If op0 is an expression ... */
6105 /* ... and has wrapping overflow, and its type is smaller
6106 than ctype, then we cannot pass through as widening. */
6112 /* ... or this is a truncation (t is narrower than op0),
6113 then we cannot pass through this narrowing. */
6116 /* ... or signedness changes for division or modulus,
6117 then we cannot pass through this conversion. */
6121 /* ... or has undefined overflow while the converted to
6122 type has not, we cannot do the operation in the inner type
6123 as that would introduce undefined overflow. */
6128 /* Pass the constant down and see if we can make a simplification. If
6129 we can, replace this expression with the inner simplification for
6130 possible later conversion to our or some other type. */
6135 code == MULT_EXPR
6137 strict_overflow_p))))
6142 /* If widening the type changes it from signed to unsigned, then we
6143 must avoid building ABS_EXPR itself as unsigned. */
6145 {
6149 {
6152 }
6154 }
6155 /* If the constant is negative, we cannot simplify this. */
6158 /* FALLTHROUGH */
6166 /* If widening the type changes the signedness, then we can't perform
6167 this optimization as that changes the result. */
6171 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6177 {
6184 }
6188 /* If the second operand is constant, this is a multiplication
6189 or floor division, by a power of two, so we can treat it that
6190 way unless the multiplier or divisor overflows. Signed
6191 left-shift overflow is implementation-defined rather than
6192 undefined in C90, so do not convert signed left shift into
6193 multiplication. */
6196 /* const_binop may not detect overflow correctly,
6197 so check for it explicitly here. */
6202 size_one_node,
6212 /* See if we can eliminate the operation on both sides. If we can, we
6213 can return a new PLUS or MINUS. If we can't, the only remaining
6214 cases where we can do anything are if the second operand is a
6215 constant. */
6221 /* If not multiplication, we can only do this if both operands
6222 are divisible by c. */
6225 {
6230 }
6232 /* If this was a subtraction, negate OP1 and set it to be an addition.
6233 This simplifies the logic below. */
6240 /* If either OP1 or C are negative, this optimization is not safe for
6241 some of the division and remainder types while for others we need
6242 to change the code. */
6244 {
6252 }
6254 /* If it's a multiply or a division/modulus operation of a multiple
6255 of our constant, do the operation and verify it doesn't overflow. */
6258 {
6261 /* We allow the constant to overflow with wrapping semantics. */
6265 }
6266 else
6269 /* If we have an unsigned type is not a sizetype, we cannot widen
6270 the operation since it will change the result if the original
6271 computation overflowed. */
6277 /* If we were able to eliminate our operation from the first side,
6278 apply our operation to the second side and reform the PLUS. */
6282 /* The last case is if we are a multiply. In that case, we can
6283 apply the distributive law to commute the multiply and addition
6284 if the multiplication of the constants doesn't overflow. */
6290 op1);
6295 /* We have a special case here if we are doing something like
6296 (C * 8) % 4 since we know that's zero. */
6299 /* If the multiplication can overflow we cannot optimize this.
6300 ??? Until we can properly mark individual operations as
6301 not overflowing we need to treat sizetype special here as
6302 stor-layout relies on this opimization to make
6303 DECL_FIELD_BIT_OFFSET always a constant. */
6309 {
6312 }
6314 /* ... fall through ... */
6318 /* If we can extract our operation from the LHS, do so and return a
6319 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6320 do something only if the second operand is a constant. */
6334 /* If these are the same operation types, we can associate them
6335 assuming no overflow. */
6347 /* If these operations "cancel" each other, we have the main
6348 optimizations of this pass, which occur when either constant is a
6349 multiple of the other, in which case we replace this with either an
6350 operation or CODE or TCODE.
6352 If we have an unsigned type that is not a sizetype, we cannot do
6353 this since it will change the result if the original computation
6354 overflowed. */
6362 {
6364 {
6371 }
6373 {
6380 }
6381 }
6386 }
6389 }
6390 \f
6391 /* Return a node which has the indicated constant VALUE (either 0 or
6392 1), and is of the indicated TYPE. */
6394 tree
6396 {
6401 else
6403 }
6406 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6407 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6408 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6409 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6410 COND is the first argument to CODE; otherwise (as in the example
6411 given here), it is the second argument. TYPE is the type of the
6412 original expression. Return NULL_TREE if no simplification is
6413 possible. */
6415 static tree
6419 {
6426 /* This transformation is only worthwhile if we don't have to wrap
6427 arg in a SAVE_EXPR, and the operation can be simplified on at least
6428 one of the branches once its pushed inside the COND_EXPR. */
6433 {
6437 /* If this operand throws an expression, then it does not make
6438 sense to try to perform a logical or arithmetic operation
6439 involving it. */
6444 }
6445 else
6446 {
6451 }
6455 {
6459 else
6461 }
6463 {
6467 else
6469 }
6473 }
6475 \f
6476 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6478 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6479 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6480 ADDEND is the same as X.
6482 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6483 and finite. The problematic cases are when X is zero, and its mode
6484 has signed zeros. In the case of rounding towards -infinity,
6485 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6486 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6488 bool
6490 {
6494 /* Don't allow the fold with -fsignaling-nans. */
6498 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6502 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6507 /* The mode has signed zeros, and we have to honor their sign.
6508 In this situation, there is only one case we can return true for.
6509 X - 0 is the same as X unless rounding towards -infinity is
6510 supported. */
6512 }
6514 /* Subroutine of fold() that checks comparisons of built-in math
6515 functions against real constants.
6517 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6518 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6519 is the type of the result and ARG0 and ARG1 are the operands of the
6520 comparison. ARG1 must be a TREE_REAL_CST.
6522 The function returns the constant folded tree if a simplification
6523 can be made, and NULL_TREE otherwise. */
6525 static tree
6528 {
6529 REAL_VALUE_TYPE c;
6532 {
6538 {
6539 /* sqrt(x) < y is always false, if y is negative. */
6543 /* sqrt(x) > y is always true, if y is negative and we
6544 don't care about NaNs, i.e. negative values of x. */
6548 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6551 }
6553 {
6554 REAL_VALUE_TYPE c2;
6560 {
6561 /* sqrt(x) > y is x == +Inf, when y is very large. */
6566 /* sqrt(x) > y is always false, when y is very large
6567 and we don't care about infinities. */
6569 }
6571 /* sqrt(x) > c is the same as x > c*c. */
6574 }
6576 {
6577 REAL_VALUE_TYPE c2;
6583 {
6584 /* sqrt(x) < y is always true, when y is a very large
6585 value and we don't care about NaNs or Infinities. */
6589 /* sqrt(x) < y is x != +Inf when y is very large and we
6590 don't care about NaNs. */
6595 /* sqrt(x) < y is x >= 0 when y is very large and we
6596 don't care about Infinities. */
6601 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6610 dconst0)),
6613 c2)));
6614 }
6616 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6621 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6624 {
6629 dconst0)),
6632 c2)));
6633 }
6634 }
6635 }
6638 }
6640 /* Subroutine of fold() that optimizes comparisons against Infinities,
6641 either +Inf or -Inf.
6643 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6644 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6645 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6647 The function returns the constant folded tree if a simplification
6648 can be made, and NULL_TREE otherwise. */
6650 static tree
6652 {
6654 REAL_VALUE_TYPE max;
6655 tree temp;
6660 /* For negative infinity swap the sense of the comparison. */
6666 {
6668 /* x > +Inf is always false, if with ignore sNANs. */
6674 /* x <= +Inf is always true, if we don't case about NaNs. */
6678 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6681 {
6684 }
6689 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6695 /* x < +Inf is always equal to x <= DBL_MAX. */
6701 /* x != +Inf is always equal to !(x > DBL_MAX). */
6713 }
6716 }
6718 /* Subroutine of fold() that optimizes comparisons of a division by
6719 a nonzero integer constant against an integer constant, i.e.
6720 X/C1 op C2.
6722 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6723 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6724 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6726 The function returns the constant folded tree if a simplification
6727 can be made, and NULL_TREE otherwise. */
6729 static tree
6731 {
6736 HOST_WIDE_INT hpart;
6741 /* We have to do this the hard way to detect unsigned overflow.
6742 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6753 {
6758 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6766 }
6768 {
6772 {
6791 }
6792 }
6793 else
6794 {
6795 /* A negative divisor reverses the relational operators. */
6801 {
6820 }
6821 }
6824 {
6845 {
6848 }
6853 {
6856 }
6861 {
6864 }
6869 {
6872 }
6877 }
6880 }
6883 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6884 equality/inequality test, then return a simplified form of the test
6885 using a sign testing. Otherwise return NULL. TYPE is the desired
6886 result type. */
6888 static tree
6890 tree result_type)
6891 {
6892 /* If this is testing a single bit, we can optimize the test. */
6896 {
6897 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6898 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6902 /* This is only a win if casting to a signed type is cheap,
6903 i.e. when arg00's type is not a partial mode. */
6906 {
6911 }
6912 }
6915 }
6917 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6918 equality/inequality test, then return a simplified form of
6919 the test using shifts and logical operations. Otherwise return
6920 NULL. TYPE is the desired result type. */
6922 tree
6924 tree result_type)
6925 {
6926 /* If this is testing a single bit, we can optimize the test. */
6930 {
6939 /* First, see if we can fold the single bit test into a sign-bit
6940 test. */
6942 result_type);
6946 /* Otherwise we have (A & C) != 0 where C is a single bit,
6947 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6948 Similarly for (A & C) == 0. */
6950 /* If INNER is a right shift of a constant and it plus BITNUM does
6951 not overflow, adjust BITNUM and INNER. */
6958 {
6961 }
6963 /* If we are going to be able to omit the AND below, we must do our
6964 operations as unsigned. If we must use the AND, we have a choice.
6965 Normally unsigned is faster, but for some machines signed is. */
6966 #ifdef LOAD_EXTEND_OP
6969 #else
6971 #endif
6987 /* Put the AND last so it can combine with more things. */
6990 /* Make sure to return the proper type. */
6994 }
6996 }
6998 /* Check whether we are allowed to reorder operands arg0 and arg1,
6999 such that the evaluation of arg1 occurs before arg0. */
7001 static bool
7003 {
7010 }
7012 /* Test whether it is preferable two swap two operands, ARG0 and
7013 ARG1, for example because ARG0 is an integer constant and ARG1
7014 isn't. If REORDER is true, only recommend swapping if we can
7015 evaluate the operands in reverse order. */
7017 bool
7019 {
7055 /* It is preferable to swap two SSA_NAME to ensure a canonical form
7056 for commutative and comparison operators. Ensuring a canonical
7057 form allows the optimizers to find additional redundancies without
7058 having to explicitly check for both orderings. */
7064 /* Put SSA_NAMEs last. */
7070 /* Put variables last. */
7077 }
7079 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
7080 ARG0 is extended to a wider type. */
7082 static tree
7084 {
7086 tree arg1_unw;
7095 #ifdef HAVE_canonicalize_funcptr_for_compare
7096 /* Disable this optimization if we're casting a function pointer
7097 type on targets that require function pointer canonicalization. */
7102 #endif
7109 /* If possible, express the comparison in the shorter mode. */
7129 /* If we are comparing with the integer that does not fit into the range
7130 of the shorter type, the result is known. */
7141 {
7168 }
7171 }
7173 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7174 ARG0 just the signedness is changed. */
7176 static tree
7179 {
7180 tree arg0_inner;
7190 #ifdef HAVE_canonicalize_funcptr_for_compare
7191 /* Disable this optimization if we're casting a function pointer
7192 type on targets that require function pointer canonicalization. */
7197 #endif
7202 /* If the conversion is from an integral subtype to its basetype
7203 leave it alone. */
7222 else
7226 }
7228 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
7229 step of the array. Reconstructs s and delta in the case of s * delta
7230 being an integer constant (and thus already folded).
7231 ADDR is the address. MULT is the multiplicative expression.
7232 If the function succeeds, the new address expression is returned. Otherwise
7233 NULL_TREE is returned. */
7235 static tree
7237 {
7241 tree itype;
7244 /* Strip the nops that might be added when converting op1 to sizetype. */
7247 /* Canonicalize op1 into a possibly non-constant delta
7248 and an INTEGER_CST s. */
7250 {
7257 {
7260 }
7262 {
7265 }
7266 else
7268 }
7270 {
7273 }
7274 else
7275 {
7276 /* Simulate we are delta * 1. */
7279 }
7282 {
7284 {
7285 /* Remember if this was a multi-dimensional array. */
7298 {
7301 }
7302 else
7303 {
7304 /* Try if delta is a multiple of step. */
7309 }
7311 /* Only fold here if we can verify we do not overflow one
7312 dimension of a multi-dimensional array. */
7314 {
7315 tree tmp;
7331 }
7334 }
7335 else
7340 }
7342 /* We found the suitable array reference. So copy everything up to it,
7343 and replace the index. */
7350 {
7354 }
7362 }
7365 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7366 means A >= Y && A != MAX, but in this case we know that
7367 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7369 static tree
7371 {
7378 else
7387 {
7390 }
7392 {
7395 }
7396 else
7403 {
7404 /* Convert the pointer types into integer before taking the difference. */
7408 }
7409 else
7416 }
7418 /* Fold a sum or difference of at least one multiplication.
7419 Returns the folded tree or NULL if no simplification could be made. */
7421 static tree
7423 {
7427 /* (A * C) +- (B * C) -> (A+-B) * C.
7428 (A * C) +- A -> A * (C+-1).
7429 We are most concerned about the case where C is a constant,
7430 but other combinations show up during loop reduction. Since
7431 it is not difficult, try all four possibilities. */
7434 {
7437 }
7439 {
7442 }
7443 else
7444 {
7445 /* We cannot generate constant 1 for fract. */
7450 }
7452 {
7455 }
7457 {
7459 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7460 the purpose of this canonicalization. */
7464 {
7467 }
7468 else
7470 }
7471 else
7472 {
7473 /* We cannot generate constant 1 for fract. */
7478 }
7490 /* No identical multiplicands; see if we can find a common
7491 power-of-two factor in non-power-of-two multiplies. This
7492 can help in multi-dimensional array access. */
7495 {
7498 tree maybe_same;
7502 /* Move min of absolute values to int11. */
7505 {
7510 }
7511 else
7515 /* The remainder should not be a constant, otherwise we
7516 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7517 increased the number of multiplications necessary. */
7519 {
7527 }
7528 }
7538 }
7540 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7541 specified by EXPR into the buffer PTR of length LEN bytes.
7542 Return the number of bytes placed in the buffer, or zero
7543 upon failure. */
7545 static int
7547 {
7558 {
7562 else
7567 {
7574 else
7576 }
7577 else
7580 }
7582 }
7585 /* Subroutine of native_encode_expr. Encode the REAL_CST
7586 specified by EXPR into the buffer PTR of length LEN bytes.
7587 Return the number of bytes placed in the buffer, or zero
7588 upon failure. */
7590 static int
7592 {
7598 /* There are always 32 bits in each long, no matter the size of
7599 the hosts long. We handle floating point representations with
7600 up to 192 bits. */
7611 {
7616 {
7623 else
7625 }
7626 else
7629 }
7631 }
7633 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7634 specified by EXPR into the buffer PTR of length LEN bytes.
7635 Return the number of bytes placed in the buffer, or zero
7636 upon failure. */
7638 static int
7640 {
7642 tree part;
7653 }
7656 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7657 specified by EXPR into the buffer PTR of length LEN bytes.
7658 Return the number of bytes placed in the buffer, or zero
7659 upon failure. */
7661 static int
7663 {
7673 {
7675 {
7678 }
7679 else
7683 {
7686 }
7687 else
7688 {
7692 }
7694 }
7696 }
7699 /* Subroutine of native_encode_expr. Encode the STRING_CST
7700 specified by EXPR into the buffer PTR of length LEN bytes.
7701 Return the number of bytes placed in the buffer, or zero
7702 upon failure. */
7704 static int
7706 {
7708 HOST_WIDE_INT total_bytes;
7719 {
7723 }
7724 else
7727 }
7730 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7731 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7732 buffer PTR of length LEN bytes. Return the number of bytes
7733 placed in the buffer, or zero upon failure. */
7735 int
7737 {
7739 {
7757 }
7758 }
7761 /* Subroutine of native_interpret_expr. Interpret the contents of
7762 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7763 If the buffer cannot be interpreted, return NULL_TREE. */
7765 static tree
7767 {
7781 {
7784 {
7791 else
7793 }
7794 else
7800 else
7803 }
7806 }
7809 /* Subroutine of native_interpret_expr. Interpret the contents of
7810 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7811 If the buffer cannot be interpreted, return NULL_TREE. */
7813 static tree
7815 {
7820 /* There are always 32 bits in each long, no matter the size of
7821 the hosts long. We handle floating point representations with
7822 up to 192 bits. */
7823 REAL_VALUE_TYPE r;
7834 {
7837 {
7844 else
7846 }
7847 else
7852 }
7856 }
7859 /* Subroutine of native_interpret_expr. Interpret the contents of
7860 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7861 If the buffer cannot be interpreted, return NULL_TREE. */
7863 static tree
7865 {
7880 }
7883 /* Subroutine of native_interpret_expr. Interpret the contents of
7884 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7885 If the buffer cannot be interpreted, return NULL_TREE. */
7887 static tree
7889 {
7901 {
7906 }
7908 }
7911 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7912 the buffer PTR of length LEN as a constant of type TYPE. For
7913 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7914 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7915 return NULL_TREE. */
7917 tree
7919 {
7921 {
7938 }
7939 }
7942 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7943 TYPE at compile-time. If we're unable to perform the conversion
7944 return NULL_TREE. */
7946 static tree
7948 {
7949 /* We support up to 512-bit values (for V8DFmode). */
7953 /* Check that the host and target are sane. */
7962 }
7964 /* Build an expression for the address of T. Folds away INDIRECT_REF
7965 to avoid confusing the gimplify process. */
7967 tree
7969 {
7970 /* The size of the object is not relevant when talking about its address. */
7974 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
7977 {
7982 }
7983 else
7987 }
7989 /* Build an expression for the address of T. */
7991 tree
7993 {
7997 }
7999 /* Fold a unary expression of code CODE and type TYPE with operand
8000 OP0. Return the folded expression if folding is successful.
8001 Otherwise, return NULL_TREE. */
8003 tree
8005 {
8006 tree tem;
8007 tree arg0;
8015 {
8018 {
8019 /* Don't use STRIP_NOPS, because signedness of argument type
8020 matters. */
8022 }
8023 else
8024 {
8025 /* Strip any conversions that don't change the mode. This
8026 is safe for every expression, except for a comparison
8027 expression because its signedness is derived from its
8028 operands.
8030 Note that this is done as an internal manipulation within
8031 the constant folder, in order to find the simplest
8032 representation of the arguments so that their form can be
8033 studied. In any cases, the appropriate type conversions
8034 should be put back in the tree that will get out of the
8035 constant folder. */
8037 }
8038 }
8041 {
8048 {
8060 /* If this was a conversion, and all we did was to move into
8061 inside the COND_EXPR, bring it back out. But leave it if
8062 it is a conversion from integer to integer and the
8063 result precision is no wider than a word since such a
8064 conversion is cheap and may be optimized away by combine,
8065 while it couldn't if it were outside the COND_EXPR. Then return
8066 so we don't get into an infinite recursion loop taking the
8067 conversion out and then back in. */
8079 && (INTEGRAL_TYPE_P
8091 }
8093 {
8095 {
8099 }
8103 integer_one_node),
8105 integer_zero_node));
8106 }
8107 }
8110 {
8112 /* Re-association barriers around constants and other re-association
8113 barriers can be removed. */
8119 CASE_CONVERT:
8125 /* If we have (type) (a CMP b) and type is an integral type, return
8126 new expression involving the new type. */
8131 /* Handle cases of two conversions in a row. */
8133 {
8155 /* In addition to the cases of two conversions in a row
8156 handled below, if we are converting something to its own
8157 type via an object of identical or wider precision, neither
8158 conversion is needed. */
8165 /* Likewise, if the intermediate and initial types are either both
8166 float or both integer, we don't need the middle conversion if the
8167 former is wider than the latter and doesn't change the signedness
8168 (for integers). Avoid this if the final type is a pointer since
8169 then we sometimes need the middle conversion. Likewise if the
8170 final type has a precision not equal to the size of its mode. */
8179 && ! final_ptr
8183 /* If we have a sign-extension of a zero-extended value, we can
8184 replace that by a single zero-extension. */
8190 /* Two conversions in a row are not needed unless:
8191 - some conversion is floating-point (overstrict for now), or
8192 - some conversion is a vector (overstrict for now), or
8193 - the intermediate type is narrower than both initial and
8194 final, or
8195 - the intermediate type and innermost type differ in signedness,
8196 and the outermost type is wider than the intermediate, or
8197 - the initial type is a pointer type and the precisions of the
8198 intermediate and final types differ, or
8199 - the final type is a pointer type and the precisions of the
8200 initial and intermediate types differ. */
8214 }
8216 /* Handle (T *)&A.B.C for A being of type T and B and C
8217 living at offset zero. This occurs frequently in
8218 C++ upcasting and then accessing the base. */
8222 {
8224 tree offset;
8230 /* If the reference was to a (constant) zero offset, we can use
8231 the address of the base if it has the same base type
8232 as the result type. */
8237 }
8241 /* Detect assigning a bitfield. */
8243 && DECL_BIT_FIELD
8245 {
8246 /* Don't leave an assignment inside a conversion
8247 unless assigning a bitfield. */
8249 /* First do the assignment, then return converted constant. */
8254 }
8256 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8257 constants (if x has signed type, the sign bit cannot be set
8258 in c). This folds extension into the BIT_AND_EXPR.
8259 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8260 very likely don't have maximal range for their precision and this
8261 transformation effectively doesn't preserve non-maximal ranges. */
8265 /* Not if the conversion is to the sub-type. */
8267 {
8277 <= HOST_BITS_PER_WIDE_INT
8279 {
8286 #ifdef LOAD_EXTEND_OP
8288 && !flag_syntax_only
8291 {
8295 }
8296 #endif
8297 }
8299 {
8305 }
8306 }
8308 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8309 when one of the new casts will fold away. Conservatively we assume
8310 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8316 {
8322 }
8324 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8325 of the same precision, and X is an integer type not narrower than
8326 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8332 {
8337 }
8339 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8340 type of X and Y (integer types only). */
8345 {
8346 /* Be careful not to introduce new overflows. */
8347 tree mult_type;
8350 else
8354 {
8361 }
8362 }
8377 /* For integral conversions with the same precision or pointer
8378 conversions use a NOP_EXPR instead. */
8384 /* Do not muck with VIEW_CONVERT_EXPRs that convert from
8385 a sub-type to its base type as generated by the Ada FE. */
8390 /* Strip inner integral conversions that do not change the precision. */
8413 /* Convert fabs((double)float) into (double)fabsf(float). */
8416 {
8421 targ0));
8422 }
8423 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8429 /* Strip sign ops from argument. */
8431 {
8435 }
8442 {
8447 }
8449 {
8454 }
8464 /* Convert ~ (-A) to A - 1. */
8469 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8477 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8490 /* Perform BIT_NOT_EXPR on each element individually. */
8492 {
8497 {
8499 {
8505 }
8506 else
8509 }
8512 }
8517 /* The argument to invert_truthvalue must have Boolean type. */
8521 /* Note that the operand of this must be an int
8522 and its values must be 0 or 1.
8523 ("true" is a fixed value perhaps depending on the language,
8524 but we don't handle values other than 1 correctly yet.) */
8539 {
8547 }
8549 {
8553 }
8555 {
8559 {
8568 }
8569 }
8581 {
8589 }
8591 {
8595 }
8597 {
8601 {
8610 }
8611 }
8617 }
8620 /* If the operation was a conversion do _not_ mark a resulting constant
8621 with TREE_OVERFLOW if the original constant was not. These conversions
8622 have implementation defined behavior and retaining the TREE_OVERFLOW
8623 flag here would confuse later passes such as VRP. */
8624 tree
8626 {
8635 }
8637 /* Fold a binary expression of code CODE and type TYPE with operands
8638 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8639 Return the folded expression if folding is successful. Otherwise,
8640 return NULL_TREE. */
8642 static tree
8644 {
8651 else
8654 /* MIN (MAX (a, b), b) == b. */
8659 /* MIN (MAX (b, a), b) == b. */
8665 /* MIN (a, MAX (a, b)) == a. */
8671 /* MIN (a, MAX (b, a)) == a. */
8678 }
8680 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8681 by changing CODE to reduce the magnitude of constants involved in
8682 ARG0 of the comparison.
8683 Returns a canonicalized comparison tree if a simplification was
8684 possible, otherwise returns NULL_TREE.
8685 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8686 valid if signed overflow is undefined. */
8688 static tree
8692 {
8698 /* Match A +- CST code arg1 and CST code arg1. We can change the
8699 first form only if overflow is undefined. */
8701 /* In principle pointers also have undefined overflow behavior,
8702 but that causes problems elsewhere. */
8710 /* Identify the constant in arg0 and its sign. */
8713 else
8717 /* Overflowed constants and zero will cause problems. */
8722 /* See if we can reduce the magnitude of the constant in
8723 arg0 by changing the comparison code. */
8725 {
8726 /* CST <= arg1 -> CST-1 < arg1. */
8729 /* -CST < arg1 -> -CST-1 <= arg1. */
8732 /* CST > arg1 -> CST-1 >= arg1. */
8735 /* -CST >= arg1 -> -CST-1 > arg1. */
8738 else
8740 /* arg1 code' CST' might be more canonical. */
8742 }
8743 else
8744 {
8745 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8749 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8753 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8757 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8761 else
8764 }
8766 /* Now build the constant reduced in magnitude. But not if that
8767 would produce one outside of its types range. */
8775 /* We cannot swap the comparison here as that would cause us to
8776 endlessly recurse. */
8784 /* If swapping might yield to a more canonical form, do so. */
8787 else
8789 }
8791 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8792 overflow further. Try to decrease the magnitude of constants involved
8793 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8794 and put sole constants at the second argument position.
8795 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8797 static tree
8800 {
8801 tree t;
8806 /* Try canonicalization by simplifying arg0. */
8811 {
8815 }
8817 /* Try canonicalization by simplifying arg1 using the swapped
8818 comparison. */
8826 }
8828 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8829 space. This is used to avoid issuing overflow warnings for
8830 expressions like &p->x which can not wrap. */
8832 static bool
8834 {
8845 {
8848 }
8851 else
8852 {
8855 }
8870 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8871 array. */
8873 {
8874 HOST_WIDE_INT base_size;
8879 }
8882 }
8884 /* Subroutine of fold_binary. This routine performs all of the
8885 transformations that are common to the equality/inequality
8886 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8887 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8888 fold_binary should call fold_binary. Fold a comparison with
8889 tree code CODE and type TYPE with operands OP0 and OP1. Return
8890 the folded comparison or NULL_TREE. */
8892 static tree
8894 {
8907 /* If one arg is a real or integer constant, put it last. */
8911 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8918 {
8922 tree lhs;
8929 /* If the constant operation overflowed this can be
8930 simplified as a comparison against INT_MAX/INT_MIN. */
8933 {
8937 /* Get the sign of the constant on the lhs if the
8938 operation were VARIABLE + CONST1. */
8942 /* The sign of the constant determines if we overflowed
8943 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8944 Canonicalize to the INT_MIN overflow by swapping the comparison
8945 if necessary. */
8949 /* We now can look at the canonicalized case
8950 VARIABLE + 1 CODE2 INT_MIN
8951 and decide on the result. */
8960 }
8965 {
8967 "when changing X +- C1 cmp C2 to "
8969 WARN_STRICT_OVERFLOW_COMPARISON);
8971 }
8972 }
8974 /* For comparisons of pointers we can decompose it to a compile time
8975 comparison of the base objects and the offsets into the object.
8976 This requires at least one operand being an ADDR_EXPR or a
8977 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8983 {
8990 /* Get base and offset for the access. Strip ADDR_EXPR for
8991 get_inner_reference, but put it back by stripping INDIRECT_REF
8992 off the base object if possible. indirect_baseN will be true
8993 if baseN is not an address but refers to the object itself. */
8996 {
9002 else
9004 }
9006 {
9009 }
9013 {
9019 else
9021 }
9023 {
9026 }
9028 /* If we have equivalent bases we might be able to simplify. */
9031 {
9032 /* We can fold this expression to a constant if the non-constant
9033 offset parts are equal. */
9041 {
9048 "occur when comparing P +- C1 with "
9050 WARN_STRICT_OVERFLOW_CONDITIONAL);
9053 {
9067 }
9068 }
9069 /* We can simplify the comparison to a comparison of the variable
9070 offset parts if the constant offset parts are equal.
9071 Be careful to use signed size type here because otherwise we
9072 mess with array offsets in the wrong way. This is possible
9073 because pointer arithmetic is restricted to retain within an
9074 object and overflow on pointer differences is undefined as of
9075 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9079 {
9080 tree signed_size_type_node;
9083 /* By converting to signed size type we cover middle-end pointer
9084 arithmetic which operates on unsigned pointer types of size
9085 type size and ARRAY_REF offsets which are properly sign or
9086 zero extended from their type in case it is narrower than
9087 size type. */
9090 else
9094 else
9102 "occur when comparing P +- C1 with "
9104 WARN_STRICT_OVERFLOW_COMPARISON);
9107 }
9108 }
9109 /* For non-equal bases we can simplify if they are addresses
9110 of local binding decls or constants. */
9112 /* We know that !operand_equal_p (base0, base1, 0)
9113 because the if condition was false. But make
9114 sure two decls are not the same. */
9128 {
9133 }
9134 /* For equal offsets we can simplify to a comparison of the
9135 base addresses. */
9137 && (indirect_base0
9139 && (indirect_base1
9144 {
9150 }
9151 }
9153 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9154 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9155 the resulting offset is smaller in absolute value than the
9156 original one. */
9164 {
9169 tree cst;
9171 "occur when combining constants around "
9174 /* Put the constant on the side where it doesn't overflow and is
9175 of lower absolute value than before. */
9181 {
9184 variable1,
9187 }
9194 {
9199 variable2);
9200 }
9201 }
9203 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9204 signed arithmetic case. That form is created by the compiler
9205 often enough for folding it to be of value. One example is in
9206 computing loop trip counts after Operator Strength Reduction. */
9212 {
9221 "eliminating multiplication in comparison "
9223 WARN_STRICT_OVERFLOW_COMPARISON);
9225 /* If const1 is negative we swap the sense of the comparison. */
9230 }
9237 {
9245 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9250 /* (-a) CMP (-b) -> b CMP a */
9257 {
9258 REAL_VALUE_TYPE cst;
9261 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9268 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9269 /* a CMP (-0) -> a CMP 0 */
9274 /* x != NaN is always true, other ops are always false. */
9277 {
9280 }
9282 /* Fold comparisons against infinity. */
9285 {
9289 }
9290 }
9292 /* If this is a comparison of a real constant with a PLUS_EXPR
9293 or a MINUS_EXPR of a real constant, we can convert it into a
9294 comparison with a revised real constant as long as no overflow
9295 occurs when unsafe_math_optimizations are enabled. */
9307 /* Likewise, we can simplify a comparison of a real constant with
9308 a MINUS_EXPR whose first operand is also a real constant, i.e.
9309 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9310 floating-point types only if -fassociative-math is set. */
9321 /* Fold comparisons against built-in math functions. */
9323 && flag_unsafe_math_optimizations
9325 {
9329 {
9333 }
9334 }
9335 }
9339 {
9340 /* If we are widening one operand of an integer comparison,
9341 see if the other operand is similarly being widened. Perhaps we
9342 can do the comparison in the narrower type. */
9347 /* Or if we are changing signedness. */
9351 }
9353 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9354 constant, we can simplify it. */
9359 {
9363 }
9365 /* Simplify comparison of something with itself. (For IEEE
9366 floating-point, we can only do some of these simplifications.) */
9368 {
9370 {
9385 /* For NE, we can only do this simplification if integer
9386 or we don't honor IEEE floating point NaNs. */
9390 /* ... fall through ... */
9396 }
9397 }
9399 /* If we are comparing an expression that just has comparisons
9400 of two integer values, arithmetic expressions of those comparisons,
9401 and constants, we can simplify it. There are only three cases
9402 to check: the two values can either be equal, the first can be
9403 greater, or the second can be greater. Fold the expression for
9404 those three values. Since each value must be 0 or 1, we have
9405 eight possibilities, each of which corresponds to the constant 0
9406 or 1 or one of the six possible comparisons.
9408 This handles common cases like (a > b) == 0 but also handles
9409 expressions like ((x > y) - (y > x)) > 0, which supposedly
9410 occur in macroized code. */
9413 {
9418 /* Don't handle degenerate cases here; they should already
9419 have been handled anyway. */
9428 {
9432 /* We can't just pass T to eval_subst in case cval1 or cval2
9433 was the same as ARG1. */
9435 tree high_result
9439 arg1);
9440 tree equal_result
9444 arg1);
9445 tree low_result
9449 arg1);
9451 /* All three of these results should be 0 or 1. Confirm they are.
9452 Then use those values to select the proper code to use. */
9457 {
9458 /* Make a 3-bit mask with the high-order bit being the
9459 value for `>', the next for '=', and the low for '<'. */
9463 {
9465 /* Always false. */
9486 /* Always true. */
9488 }
9493 }
9494 }
9495 }
9497 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9498 into a single range test. */
9506 {
9510 }
9512 /* Fold ~X op ~Y as Y op X. */
9515 {
9520 }
9522 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9525 {
9531 }
9534 }
9537 /* Subroutine of fold_binary. Optimize complex multiplications of the
9538 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9539 argument EXPR represents the expression "z" of type TYPE. */
9541 static tree
9543 {
9548 {
9551 }
9553 {
9556 }
9557 else
9558 {
9562 }
9571 }
9574 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9575 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9576 guarantees that P and N have the same least significant log2(M) bits.
9577 N is not otherwise constrained. In particular, N is not normalized to
9578 0 <= N < M as is common. In general, the precise value of P is unknown.
9579 M is chosen as large as possible such that constant N can be determined.
9581 Returns M and sets *RESIDUE to N.
9583 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9584 account. This is not always possible due to PR 35705.
9585 */
9587 static unsigned HOST_WIDE_INT
9590 {
9597 {
9600 {
9602 tree offset;
9610 {
9613 else
9614 /* We don't handle more complicated offset expressions. */
9616 }
9617 }
9622 }
9624 {
9632 allow_func_align);
9638 {
9641 }
9643 {
9646 {
9649 /* Compute the greatest power-of-2 divisor of op1. */
9653 /* If align is non-zero and less than *modulus, replace
9654 *modulus with align., If align is 0, then either op1 is 0
9655 or the greatest power-of-2 divisor of op1 doesn't fit in an
9656 unsigned HOST_WIDE_INT. In either case, no additional
9657 constraint is imposed. */
9662 }
9663 }
9664 }
9666 /* If we get here, we were unable to determine anything useful about the
9667 expression. */
9669 }
9672 /* Fold a binary expression of code CODE and type TYPE with operands
9673 OP0 and OP1. Return the folded expression if folding is
9674 successful. Otherwise, return NULL_TREE. */
9676 tree
9678 {
9692 /* Strip any conversions that don't change the mode. This is
9693 safe for every expression, except for a comparison expression
9694 because its signedness is derived from its operands. So, in
9695 the latter case, only strip conversions that don't change the
9696 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9697 preserved.
9699 Note that this is done as an internal manipulation within the
9700 constant folder, in order to find the simplest representation
9701 of the arguments so that their form can be studied. In any
9702 cases, the appropriate type conversions should be put back in
9703 the tree that will get out of the constant folder. */
9706 {
9709 }
9710 else
9711 {
9714 }
9716 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9717 constant but we can't do arithmetic on them. */
9724 {
9726 {
9727 /* Make sure type and arg0 have the same saturating flag. */
9731 }
9734 else
9738 {
9742 }
9743 }
9745 /* If this is a commutative operation, and ARG0 is a constant, move it
9746 to ARG1 to reduce the number of tests below. */
9751 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9753 First check for cases where an arithmetic operation is applied to a
9754 compound, conditional, or comparison operation. Push the arithmetic
9755 operation inside the compound or conditional to see if any folding
9756 can then be done. Convert comparison to conditional for this purpose.
9757 The also optimizes non-constant cases that used to be done in
9758 expand_expr.
9760 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9761 one of the operands is a comparison and the other is a comparison, a
9762 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9763 code below would make the expression more complex. Change it to a
9764 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9765 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9777 {
9781 boolean_type_node,
9789 }
9793 {
9799 op1));
9808 {
9814 }
9817 {
9823 }
9824 }
9827 {
9829 /* 0 +p index -> (type)index */
9833 /* PTR +p 0 -> PTR */
9837 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9844 /* index +p PTR -> PTR +p index */
9851 /* (PTR +p B) +p A -> PTR +p (B + A) */
9853 {
9854 tree inner;
9862 }
9864 /* PTR_CST +p CST -> CST1 */
9868 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9869 of the array. Loop optimizer sometimes produce this type of
9870 expressions. */
9872 {
9876 }
9881 /* A + (-B) -> A - B */
9886 /* (-A) + B -> B - A */
9894 {
9895 /* Convert ~A + 1 to -A. */
9901 /* ~X + X is -1. */
9904 {
9909 {
9912 }
9913 }
9915 /* X + ~X is -1. */
9918 {
9923 {
9926 }
9927 }
9929 /* X + (X / CST) * -CST is X % CST. */
9934 {
9942 }
9943 }
9945 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9946 same or one. Make sure type is not saturating.
9947 fold_plusminus_mult_expr will re-associate. */
9952 {
9956 }
9959 {
9963 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9964 with a constant, and the two constants have no bits in common,
9965 we should treat this as a BIT_IOR_EXPR since this may produce more
9966 simplifications. */
9974 {
9977 }
9979 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9980 (plus (plus (mult) (mult)) (foo)) so that we can
9981 take advantage of the factoring cases below. */
9988 {
9994 else
10016 parg1)));
10017 }
10018 }
10019 else
10020 {
10021 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10025 /* Likewise if the operands are reversed. */
10029 /* Convert X + -C into X - C. */
10032 {
10038 }
10040 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10041 to __complex__ ( x, y ). This is not the same for SNaNs or
10042 if signed zeros are involved. */
10046 {
10053 {
10057 {
10063 }
10065 {
10071 }
10072 }
10073 }
10081 /* Convert x+x into x*2.0. */
10087 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10088 We associate floats only if the user has specified
10089 -fassociative-math. */
10093 {
10098 {
10099 tree tree0;
10102 }
10103 }
10104 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10105 We associate floats only if the user has specified
10106 -fassociative-math. */
10110 {
10115 {
10116 tree tree0;
10119 }
10120 }
10121 }
10123 bit_rotate:
10124 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10125 is a rotate of A by C1 bits. */
10126 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10127 is a rotate of A by B bits. */
10128 {
10130 tree rtype;
10139 /* Only create rotates in complete modes. Other cases are not
10140 expanded properly. */
10142 {
10161 {
10169 TYPE_PRECISION
10174 ? LROTATE_EXPR
10177 }
10179 {
10187 TYPE_PRECISION
10192 ? LROTATE_EXPR
10195 }
10196 }
10197 }
10199 associate:
10200 /* In most languages, can't associate operations on floats through
10201 parentheses. Rather than remember where the parentheses were, we
10202 don't associate floats at all, unless the user has specified
10203 -fassociative-math.
10204 And, we need to make sure type is not saturating. */
10208 {
10213 /* Split both trees into variables, constants, and literals. Then
10214 associate each group together, the constants with literals,
10215 then the result with variables. This increases the chances of
10216 literals being recombined later and of generating relocatable
10217 expressions for the sum of a constant and literal. */
10222 /* With undefined overflow we can only associate constants
10223 with one variable. */
10227 {
10235 /* The only case we can still associate with two variables
10236 is if they are the same, modulo negation. */
10239 }
10241 /* Only do something if we found more than two objects. Otherwise,
10242 nothing has changed and we risk infinite recursion. */
10248 {
10249 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10258 /* Preserve the MINUS_EXPR if the negative part of the literal is
10259 greater than the positive part. Otherwise, the multiplicative
10260 folding code (i.e extract_muldiv) may be fooled in case
10261 unsigned constants are subtracted, like in the following
10262 example: ((X*2 + 4) - 8U)/2. */
10264 {
10268 {
10272 }
10273 else
10274 {
10278 }
10279 }
10281 {
10286 else
10287 {
10293 }
10294 }
10299 }
10300 }
10305 /* Pointer simplifications for subtraction, simple reassociations. */
10307 {
10308 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10311 {
10319 }
10320 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10322 {
10328 }
10329 }
10330 /* A - (-B) -> A + B */
10334 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10343 /* Convert -A - 1 to ~A. */
10351 /* Convert -1 - A to ~A. */
10357 /* X - (X / CST) * CST is X % CST. */
10370 {
10376 /* Fold A - (A & B) into ~B & A. */
10379 {
10381 {
10386 }
10388 {
10393 }
10394 }
10396 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10397 any power of 2 minus 1. */
10402 {
10408 {
10412 }
10413 }
10414 }
10416 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10420 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10421 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10422 (-ARG1 + ARG0) reduces to -ARG1. */
10426 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10427 __complex__ ( x, -y ). This is not the same for SNaNs or if
10428 signed zeros are involved. */
10432 {
10439 {
10443 {
10445 arg1r ? arg1r
10450 }
10452 {
10456 arg1i ? arg1i
10459 }
10460 }
10461 }
10463 /* Fold &x - &x. This can happen from &x.foo - &x.
10464 This is unsafe for certain floats even in non-IEEE formats.
10465 In IEEE, it is unsafe because it does wrong for NaNs.
10466 Also note that operand_equal_p is always false if an operand
10467 is volatile. */
10473 /* A - B -> A + (-B) if B is easily negatable. */
10476 /* Avoid this transformation if B is a positive REAL_CST. */
10484 /* Try folding difference of addresses. */
10485 {
10486 HOST_WIDE_INT diff;
10492 }
10494 /* Fold &a[i] - &a[j] to i-j. */
10499 {
10504 {
10512 }
10513 }
10521 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10522 same or one. Make sure type is not saturating.
10523 fold_plusminus_mult_expr will re-associate. */
10528 {
10532 }
10537 /* (-A) * (-B) -> A * B */
10548 {
10553 /* Transform x * -1 into -x. Make sure to do the negation
10554 on the original operand with conversions not stripped
10555 because we can only strip non-sign-changing conversions. */
10558 /* Transform x * -C into -x * C if x is easily negatable. */
10567 /* (a * (1 << b)) is (a << b) */
10577 /* (A + A) * C -> A * 2 * C */
10592 {
10595 "occur when simplifying "
10597 WARN_STRICT_OVERFLOW_MISC);
10599 }
10601 /* Optimize z * conj(z) for integer complex numbers. */
10608 }
10609 else
10610 {
10611 /* Maybe fold x * 0 to 0. The expressions aren't the same
10612 when x is NaN, since x * 0 is also NaN. Nor are they the
10613 same in modes with signed zeros, since multiplying a
10614 negative value by 0 gives -0, not +0. */
10619 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
10624 /* Transform x * -1.0 into -x. */
10629 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10630 the result for floating point types due to rounding so it is applied
10631 only if -fassociative-math was specify. */
10636 {
10642 }
10644 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10646 {
10649 {
10652 }
10653 }
10655 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10656 This is not the same for NaNs or if signed zeros are
10657 involved. */
10663 {
10675 }
10677 /* Optimize z * conj(z) for floating point complex numbers.
10678 Guarded by flag_unsafe_math_optimizations as non-finite
10679 imaginary components don't produce scalar results. */
10690 {
10694 /* Optimizations of root(...)*root(...). */
10696 {
10701 /* Optimize sqrt(x)*sqrt(x) as x. */
10707 /* Optimize root(x)*root(y) as root(x*y). */
10711 }
10713 /* Optimize expN(x)*expN(y) as expN(x+y). */
10715 {
10721 }
10723 /* Optimizations of pow(...)*pow(...). */
10727 {
10733 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10735 {
10739 }
10741 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10743 {
10747 }
10748 }
10750 /* Optimize tan(x)*cos(x) as sin(x). */
10759 {
10764 }
10766 /* Optimize x*pow(x,c) as pow(x,c+1). */
10770 {
10776 {
10778 REAL_VALUE_TYPE c;
10779 tree arg;
10785 }
10786 }
10788 /* Optimize pow(x,c)*x as pow(x,c+1). */
10792 {
10798 {
10800 REAL_VALUE_TYPE c;
10801 tree arg;
10807 }
10808 }
10810 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10813 {
10817 {
10820 }
10821 }
10822 }
10823 }
10827 bit_ior:
10835 /* ~X | X is -1. */
10838 {
10842 }
10844 /* X | ~X is -1. */
10847 {
10851 }
10853 /* Canonicalize (X & C1) | C2. */
10857 {
10865 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10870 {
10874 }
10875 else
10876 {
10880 }
10882 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10887 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10888 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10889 mode which allows further optimizations. */
10899 {
10900 unsigned HOST_WIDE_INT mask
10904 {
10908 }
10909 }
10916 arg1);
10917 }
10919 /* (X & Y) | Y is (X, Y). */
10923 /* (X & Y) | X is (Y, X). */
10928 /* X | (X & Y) is (Y, X). */
10933 /* X | (Y & X) is (Y, X). */
10943 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10945 This results in more efficient code for machines without a NAND
10946 instruction. Combine will canonicalize to the first form
10947 which will allow use of NAND instructions provided by the
10948 backend if they exist. */
10951 {
10958 }
10960 /* See if this can be simplified into a rotate first. If that
10961 is unsuccessful continue in the association code. */
10972 /* ~X ^ X is -1. */
10975 {
10979 }
10981 /* X ^ ~X is -1. */
10984 {
10988 }
10990 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10991 with a constant, and the two constants have no bits in common,
10992 we should treat this as a BIT_IOR_EXPR since this may produce more
10993 simplifications. */
11001 {
11004 }
11006 /* (X | Y) ^ X -> Y & ~ X*/
11009 {
11012 arg1);
11016 }
11018 /* (Y | X) ^ X -> Y & ~ X*/
11021 {
11024 arg1);
11028 }
11030 /* X ^ (X | Y) -> Y & ~ X*/
11033 {
11036 arg0);
11040 }
11042 /* X ^ (Y | X) -> Y & ~ X*/
11045 {
11048 arg0);
11052 }
11054 /* Convert ~X ^ ~Y to X ^ Y. */
11061 /* Convert ~X ^ C to X ^ ~C. */
11068 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11075 /* Fold (X & Y) ^ Y as ~X & Y. */
11078 {
11083 }
11084 /* Fold (X & Y) ^ X as ~Y & X. */
11088 {
11093 }
11094 /* Fold X ^ (X & Y) as X & ~Y. */
11097 {
11102 }
11103 /* Fold X ^ (Y & X) as ~Y & X. */
11107 {
11112 }
11114 /* See if this can be simplified into a rotate first. If that
11115 is unsuccessful continue in the association code. */
11126 /* ~X & X is always zero. */
11131 /* X & ~X is always zero. */
11136 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11140 {
11148 }
11150 /* (X | Y) & Y is (X, Y). */
11154 /* (X | Y) & X is (Y, X). */
11159 /* X & (X | Y) is (Y, X). */
11164 /* X & (Y | X) is (Y, X). */
11170 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11174 {
11180 }
11181 /* Fold ~X & 1 as (X & 1) == 0. */
11184 {
11190 }
11192 /* Fold (X ^ Y) & Y as ~X & Y. */
11195 {
11200 }
11201 /* Fold (X ^ Y) & X as ~Y & X. */
11205 {
11210 }
11211 /* Fold X & (X ^ Y) as X & ~Y. */
11214 {
11219 }
11220 /* Fold X & (Y ^ X) as ~Y & X. */
11224 {
11229 }
11234 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11237 {
11238 unsigned int prec
11245 }
11247 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11249 This results in more efficient code for machines without a NOR
11250 instruction. Combine will canonicalize to the first form
11251 which will allow use of NOR instructions provided by the
11252 backend if they exist. */
11255 {
11262 }
11264 /* If arg0 is derived from the address of an object or function, we may
11265 be able to fold this expression using the object or function's
11266 alignment. */
11268 {
11275 /* This works because modulus is a power of 2. If this weren't the
11276 case, we'd have to replace it by its greatest power-of-2
11277 divisor: modulus & -modulus. */
11280 }
11282 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11283 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11284 if the new mask might be further optimized. */
11293 {
11295 unsigned HOST_WIDE_INT mask
11305 {
11308 /* See if more bits can be proven as zero because of
11309 zero extension. */
11312 {
11317 {
11319 /* See if we can shorten the right shift. */
11322 }
11323 }
11327 /* For arithmetic shift if sign bit could be set, zerobits
11328 can contain actually sign bits, so no transformation is
11329 possible, unless MASK masks them all away. In that
11330 case the shift needs to be converted into logical shift. */
11333 {
11336 else
11338 }
11339 }
11341 /* ((X << 16) & 0xff00) is (X, 0). */
11347 {
11350 /* Only do the transformation if NEWMASK is some integer
11351 mode's mask. */
11358 {
11360 {
11366 }
11367 else
11371 newmask));
11372 }
11373 }
11374 }
11379 /* Don't touch a floating-point divide by zero unless the mode
11380 of the constant can represent infinity. */
11386 /* Optimize A / A to 1.0 if we don't care about
11387 NaNs or Infinities. Skip the transformation
11388 for non-real operands. */
11393 {
11397 }
11399 /* The complex version of the above A / A optimization. */
11402 {
11406 {
11408 /* omit_two_operands will call fold_convert for us. */
11410 }
11411 }
11413 /* (-A) / (-B) -> A / B */
11423 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11428 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11433 /* If ARG1 is a constant, we can convert this to a multiply by the
11434 reciprocal. This does not have the same rounding properties,
11435 so only do this if -freciprocal-math. We can actually
11436 always safely do it if ARG1 is a power of two, but it's hard to
11437 tell if it is or not in a portable manner. */
11439 {
11444 /* Find the reciprocal if optimizing and the result is exact. */
11446 {
11447 REAL_VALUE_TYPE r;
11450 {
11454 }
11455 }
11456 }
11457 /* Convert A/B/C to A/(B*C). */
11464 /* Convert A/(B/C) to (A/B)*C. */
11472 /* Convert C1/(X*C2) into (C1/C2)/X. */
11477 {
11483 }
11486 {
11490 /* Optimize sin(x)/cos(x) as tan(x). */
11496 {
11501 }
11503 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11509 {
11513 {
11517 }
11518 }
11520 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11521 NaNs or Infinities. */
11525 {
11532 {
11537 }
11538 }
11540 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11541 NaNs or Infinities. */
11545 {
11552 {
11556 {
11560 tmp);
11561 }
11562 }
11563 }
11565 /* Optimize pow(x,c)/x as pow(x,c-1). */
11569 {
11575 {
11577 REAL_VALUE_TYPE c;
11578 tree arg;
11584 }
11585 }
11587 /* Optimize a/root(b/c) into a*root(c/b). */
11589 {
11593 {
11602 }
11603 }
11605 /* Optimize x/expN(y) into x*expN(-y). */
11607 {
11612 }
11614 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11618 {
11625 }
11626 }
11631 /* Simplify A / (B << N) where A and B are positive and B is
11632 a power of 2, to A >> (N + log2(B)). */
11637 {
11640 {
11647 WARN_STRICT_OVERFLOW_MISC);
11653 }
11654 }
11656 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11657 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11663 /* Fall thru */
11672 /* X / -1 is -X. */
11679 /* Convert -A / -B to A / B when the type is signed and overflow is
11680 undefined. */
11684 {
11687 "when distributing negation across "
11689 WARN_STRICT_OVERFLOW_MISC);
11693 }
11697 {
11700 "when distributing negation across "
11702 WARN_STRICT_OVERFLOW_MISC);
11706 }
11708 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11709 operation, EXACT_DIV_EXPR.
11711 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11712 At one time others generated faster code, it's not clear if they do
11713 after the last round to changes to the DIV code in expmed.c. */
11722 {
11726 WARN_STRICT_OVERFLOW_MISC);
11728 }
11736 /* X % 1 is always zero, but be sure to preserve any side
11737 effects in X. */
11741 /* X % 0, return X % 0 unchanged so that we can get the
11742 proper warnings and errors. */
11746 /* 0 % X is always zero, but be sure to preserve any side
11747 effects in X. Place this after checking for X == 0. */
11751 /* X % -1 is zero. */
11758 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11759 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11764 {
11766 /* Also optimize A % (C << N) where C is a power of 2,
11767 to A & ((C << N) - 1). */
11772 {
11777 "occur when simplifying "
11779 WARN_STRICT_OVERFLOW_MISC);
11783 }
11784 }
11786 /* X % -C is the same as X % C. */
11793 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11798 /* X % -Y is the same as X % Y. */
11809 {
11813 WARN_STRICT_OVERFLOW_MISC);
11815 }
11826 /* Optimize -1 >> x for arithmetic right shifts. */
11830 /* ... fall through ... */
11833 shift:
11839 /* Since negative shift count is not well-defined,
11840 don't try to compute it in the compiler. */
11844 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11849 {
11853 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11854 being well defined. */
11856 {
11861 else
11863 }
11867 }
11869 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11870 into x & ((unsigned)-1 >> c) for unsigned types. */
11878 {
11881 tree lshift;
11882 tree arg00;
11885 {
11892 }
11893 }
11895 /* Rewrite an LROTATE_EXPR by a constant into an
11896 RROTATE_EXPR by a new constant. */
11898 {
11903 }
11905 /* If we have a rotate of a bit operation with the rotate count and
11906 the second operand of the bit operation both constant,
11907 permute the two operations. */
11919 /* Two consecutive rotates adding up to the precision of the
11920 type can be ignored. */
11931 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11932 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11933 if the latter can be further optimized. */
11938 {
11941 arg1);
11944 arg1);
11948 }
11976 /* Note that the operands of this must be ints
11977 and their values must be 0 or 1.
11978 ("true" is a fixed value perhaps depending on the language.) */
11979 /* If first arg is constant zero, return it. */
11983 /* If either arg is constant true, drop it. */
11987 /* Preserve sequence points. */
11990 /* If second arg is constant zero, result is zero, but first arg
11991 must be evaluated. */
11994 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11995 case will be handled here. */
11999 /* !X && X is always false. */
12003 /* X && !X is always false. */
12008 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12009 means A >= Y && A != MAX, but in this case we know that
12010 A < X <= MAX. */
12014 {
12022 }
12024 truth_andor:
12025 /* We only do these simplifications if we are optimizing. */
12029 /* Check for things like (A || B) && (A || C). We can convert this
12030 to A || (B && C). Note that either operator can be any of the four
12031 truth and/or operations and the transformation will still be
12032 valid. Also note that we only care about order for the
12033 ANDIF and ORIF operators. If B contains side effects, this
12034 might change the truth-value of A. */
12041 {
12061 /* This case if tricky because we must either have commutative
12062 operators or else A10 must not have side-effects. */
12068 a01);
12069 }
12071 /* See if we can build a range comparison. */
12075 /* Check for the possibility of merging component references. If our
12076 lhs is another similar operation, try to merge its rhs with our
12077 rhs. Then try to merge our lhs and rhs. */
12089 /* Note that the operands of this must be ints
12090 and their values must be 0 or true.
12091 ("true" is a fixed value perhaps depending on the language.) */
12092 /* If first arg is constant true, return it. */
12096 /* If either arg is constant zero, drop it. */
12100 /* Preserve sequence points. */
12103 /* If second arg is constant true, result is true, but we must
12104 evaluate first arg. */
12107 /* Likewise for first arg, but note this only occurs here for
12108 TRUTH_OR_EXPR. */
12112 /* !X || X is always true. */
12116 /* X || !X is always true. */
12124 /* If the second arg is constant zero, drop it. */
12127 /* If the second arg is constant true, this is a logical inversion. */
12129 {
12130 /* Only call invert_truthvalue if operand is a truth value. */
12133 else
12136 }
12137 /* Identical arguments cancel to zero. */
12141 /* !X ^ X is always true. */
12146 /* X ^ !X is always true. */
12159 /* bool_var != 0 becomes bool_var. */
12164 /* bool_var == 1 becomes bool_var. */
12169 /* bool_var != 1 becomes !bool_var. */
12174 /* bool_var == 0 becomes !bool_var. */
12179 /* If this is an equality comparison of the address of two non-weak,
12180 unaliased symbols neither of which are extern (since we do not
12181 have access to attributes for externs), then we know the result. */
12194 {
12195 /* We know that we're looking at the address of two
12196 non-weak, unaliased, static _DECL nodes.
12198 It is both wasteful and incorrect to call operand_equal_p
12199 to compare the two ADDR_EXPR nodes. It is wasteful in that
12200 all we need to do is test pointer equality for the arguments
12201 to the two ADDR_EXPR nodes. It is incorrect to use
12202 operand_equal_p as that function is NOT equivalent to a
12203 C equality test. It can in fact return false for two
12204 objects which would test as equal using the C equality
12205 operator. */
12209 type);
12210 }
12212 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12213 a MINUS_EXPR of a constant, we can convert it into a comparison with
12214 a revised constant as long as no overflow occurs. */
12226 /* Similarly for a NEGATE_EXPR. */
12234 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12243 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12250 {
12254 val,
12258 }
12260 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12265 {
12267 code == NE_EXPR
12270 }
12272 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12273 for !=. Don't do this for ordered comparisons due to overflow. */
12279 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12284 /* If this is an EQ or NE comparison with zero and ARG0 is
12285 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12286 two operations, but the latter can be done in one less insn
12287 on machines that have only two-operand insns or on which a
12288 constant cannot be the first operand. */
12291 {
12296 {
12303 }
12306 {
12313 }
12314 }
12316 /* If this is an NE or EQ comparison of zero against the result of a
12317 signed MOD operation whose second operand is a power of 2, make
12318 the MOD operation unsigned since it is simpler and equivalent. */
12326 {
12336 }
12338 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12339 C1 is a valid shift constant, and C2 is a power of two, i.e.
12340 a single bit. */
12344 == INTEGER_CST
12347 {
12352 /* Check for a valid shift count. */
12355 {
12359 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12360 can be rewritten as (X & (C2 << C1)) != 0. */
12362 {
12366 }
12367 /* Otherwise, for signed (arithmetic) shifts,
12368 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12369 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12373 /* Otherwise, of unsigned (logical) shifts,
12374 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12375 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12376 else
12380 arg000);
12381 }
12382 }
12384 /* If this is an NE comparison of zero with an AND of one, remove the
12385 comparison since the AND will give the correct value. */
12392 /* If we have (A & C) == C where C is a power of 2, convert this into
12393 (A & C) != 0. Similarly for NE_EXPR. */
12399 integer_zero_node));
12401 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12402 bit, then fold the expression into A < 0 or A >= 0. */
12407 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12408 Similarly for NE_EXPR. */
12412 {
12421 }
12423 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12424 Similarly for NE_EXPR. */
12428 {
12435 }
12437 /* If this is a comparison of a field, we may be able to simplify it. */
12440 /* Handle the constant case even without -O
12441 to make sure the warnings are given. */
12443 {
12447 }
12449 /* Optimize comparisons of strlen vs zero to a compare of the
12450 first character of the string vs zero. To wit,
12451 strlen(ptr) == 0 => *ptr == 0
12452 strlen(ptr) != 0 => *ptr != 0
12453 Other cases should reduce to one of these two (or a constant)
12454 due to the return value of strlen being unsigned. */
12457 {
12465 {
12469 }
12470 }
12472 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12473 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12477 {
12484 {
12486 {
12489 }
12492 }
12493 }
12495 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12501 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12506 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12513 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12521 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12522 (X & C) == 0 when C is a single bit. */
12527 {
12533 }
12535 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12536 constant C is a power of two, i.e. a single bit. */
12543 {
12547 }
12549 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12550 when is C is a power of two, i.e. a single bit. */
12557 {
12563 }
12567 {
12570 }
12572 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12579 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12582 {
12594 arg01),
12602 arg01),
12610 arg00),
12618 arg00),
12620 }
12624 {
12631 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12632 operand_equal_p guarantees no side-effects so we don't need
12633 to use omit_one_operand on Z. */
12643 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12650 arg10);
12651 }
12653 /* Attempt to simplify equality/inequality comparisons of complex
12654 values. Only lower the comparison if the result is known or
12655 can be simplified to a single scalar comparison. */
12660 {
12665 {
12668 }
12669 else
12670 {
12673 }
12676 {
12679 }
12680 else
12681 {
12684 }
12688 {
12690 {
12695 }
12696 else
12697 {
12702 }
12703 }
12707 {
12709 {
12714 }
12715 else
12716 {
12721 }
12722 }
12723 }
12735 /* Transform comparisons of the form X +- C CMP X. */
12742 {
12749 else
12752 /* (X - c) > X becomes false. */
12756 {
12760 "occur when assuming that (X - c) > X "
12762 WARN_STRICT_OVERFLOW_ALL);
12764 }
12766 /* Likewise (X + c) < X becomes false. */
12770 {
12774 "occur when assuming that "
12776 WARN_STRICT_OVERFLOW_ALL);
12778 }
12780 /* Convert (X - c) <= X to true. */
12785 {
12789 "occur when assuming that "
12791 WARN_STRICT_OVERFLOW_ALL);
12793 }
12795 /* Convert (X + c) >= X to true. */
12800 {
12804 "occur when assuming that "
12806 WARN_STRICT_OVERFLOW_ALL);
12808 }
12811 {
12812 /* Convert X + c > X and X - c < X to true for integers. */
12816 {
12819 "not occur when assuming that "
12821 WARN_STRICT_OVERFLOW_ALL);
12823 }
12828 {
12831 "not occur when assuming that "
12833 WARN_STRICT_OVERFLOW_ALL);
12835 }
12837 /* Convert X + c <= X and X - c >= X to false for integers. */
12841 {
12844 "not occur when assuming that "
12846 WARN_STRICT_OVERFLOW_ALL);
12848 }
12853 {
12856 "not occur when assuming that "
12858 WARN_STRICT_OVERFLOW_ALL);
12860 }
12861 }
12862 }
12864 /* Comparisons with the highest or lowest possible integer of
12865 the specified precision will have known values. */
12866 {
12873 {
12874 HOST_WIDE_INT signed_max_hi;
12879 {
12886 {
12890 }
12891 else
12892 {
12896 }
12897 }
12898 else
12899 {
12908 {
12911 }
12912 else
12913 {
12916 }
12917 }
12922 {
12935 /* The GE_EXPR and LT_EXPR cases above are not normally
12936 reached because of previous transformations. */
12940 }
12942 == max_hi
12945 {
12951 arg1);
12957 arg1);
12960 }
12962 == min_hi
12965 {
12980 }
12982 == min_hi
12985 {
12990 arg1);
12995 arg1);
12998 }
13003 /* We will flip the signedness of the comparison operator
13004 associated with the mode of arg1, so the sign bit is
13005 specified by this mode. Check that arg1 is the signed
13006 max associated with this sign bit. */
13008 /* signed_type does not work on pointer types. */
13010 {
13011 /* The following case also applies to X < signed_max+1
13012 and X >= signed_max+1 because previous transformations. */
13014 {
13015 tree st;
13020 }
13021 }
13022 }
13023 }
13025 /* If we are comparing an ABS_EXPR with a constant, we can
13026 convert all the cases into explicit comparisons, but they may
13027 well not be faster than doing the ABS and one comparison.
13028 But ABS (X) <= C is a range comparison, which becomes a subtraction
13029 and a comparison, and is probably faster. */
13043 /* Convert ABS_EXPR<x> >= 0 to true. */
13050 {
13053 "when simplifying comparison of "
13055 WARN_STRICT_OVERFLOW_CONDITIONAL);
13057 }
13059 /* Convert ABS_EXPR<x> < 0 to false. */
13064 {
13067 "when simplifying comparison of "
13069 WARN_STRICT_OVERFLOW_CONDITIONAL);
13071 }
13073 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13074 and similarly for >= into !=. */
13089 return
13108 {
13112 }
13114 /* If the first operand is NaN, the result is constant. */
13118 {
13120 ? integer_zero_node
13123 }
13125 /* If the second operand is NaN, the result is constant. */
13129 {
13131 ? integer_zero_node
13134 }
13136 /* Simplify unordered comparison of something with itself. */
13142 && !flag_trapping_math
13146 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13147 {
13158 }
13163 /* When pedantic, a compound expression can be neither an lvalue
13164 nor an integer constant expression. */
13167 /* Don't let (0, 0) be null pointer constant. */
13181 /* An ASSERT_EXPR should never be passed to fold_binary. */
13187 }
13189 /* Callback for walk_tree, looking for LABEL_EXPR.
13190 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
13191 Do not check the sub-tree of GOTO_EXPR. */
13193 static tree
13197 {
13199 {
13204 /* no break */
13207 }
13208 }
13210 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
13211 accessible from outside the sub-tree. Returns NULL_TREE if no
13212 addressable label is found. */
13214 static bool
13216 {
13218 }
13220 /* Fold a ternary expression of code CODE and type TYPE with operands
13221 OP0, OP1, and OP2. Return the folded expression if folding is
13222 successful. Otherwise, return NULL_TREE. */
13224 tree
13226 {
13227 tree tem;
13234 /* Strip any conversions that don't change the mode. This is safe
13235 for every expression, except for a comparison expression because
13236 its signedness is derived from its operands. So, in the latter
13237 case, only strip conversions that don't change the signedness.
13239 Note that this is done as an internal manipulation within the
13240 constant folder, in order to find the simplest representation of
13241 the arguments so that their form can be studied. In any cases,
13242 the appropriate type conversions should be put back in the tree
13243 that will get out of the constant folder. */
13245 {
13248 }
13251 {
13254 }
13257 {
13261 {
13267 }
13271 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13272 so all simple results must be passed through pedantic_non_lvalue. */
13274 {
13277 /* Only optimize constant conditions when the selected branch
13278 has the same type as the COND_EXPR. This avoids optimizing
13279 away "c ? x : throw", where the throw has a void type.
13280 Avoid throwing away that operand which contains label. */
13287 }
13291 /* If we have A op B ? A : C, we may be able to convert this to a
13292 simpler expression, depending on the operation and the values
13293 of B and C. Signed zeros prevent all of these transformations,
13294 for reasons given above each one.
13296 Also try swapping the arguments and inverting the conditional. */
13301 {
13305 }
13309 op2,
13312 {
13315 {
13319 }
13320 }
13322 /* If the second operand is simpler than the third, swap them
13323 since that produces better jump optimization results. */
13326 {
13327 /* See if this can be inverted. If it can't, possibly because
13328 it was a floating-point inequality comparison, don't do
13329 anything. */
13333 }
13335 /* Convert A ? 1 : 0 to simply A. */
13338 /* If we try to convert OP0 to our type, the
13339 call to fold will try to move the conversion inside
13340 a COND, which will recurse. In that case, the COND_EXPR
13341 is probably the best choice, so leave it alone. */
13345 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13346 over COND_EXPR in cases such as floating point comparisons. */
13353 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13358 {
13359 /* sign_bit_p only checks ARG1 bits within A's precision.
13360 If <sign bit of A> has wider type than A, bits outside
13361 of A's precision in <sign bit of A> need to be checked.
13362 If they are all 0, this optimization needs to be done
13363 in unsigned A's type, if they are all 1 in signed A's type,
13364 otherwise this can't be done. */
13369 {
13371 HOST_WIDE_INT mask_hi;
13373 tree tem_type;
13381 {
13385 }
13386 else
13387 {
13391 }
13393 {
13397 }
13398 else
13404 {
13407 }
13410 {
13413 }
13414 else
13416 }
13423 arg1)));
13424 }
13426 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13427 already handled above. */
13432 {
13441 }
13443 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13444 is probably obsolete because the first operand should be a
13445 truth value (that's why we have the two cases above), but let's
13446 leave it in until we can confirm this for all front-ends. */
13457 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13463 arg1);
13465 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13469 {
13470 /* Only perform transformation if ARG0 is easily inverted. */
13475 arg1);
13476 }
13478 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13482 {
13483 /* Only perform transformation if ARG0 is easily inverted. */
13488 op2);
13489 }
13491 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13497 op2);
13502 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13503 of fold_ternary on them. */
13510 {
13519 {
13524 else
13525 {
13527 tree value;
13531 }
13536 else
13538 }
13539 }
13541 /* A bit-field-ref that referenced the full argument can be stripped. */
13552 }
13554 /* Perform constant folding and related simplification of EXPR.
13555 The related simplifications include x*1 => x, x*0 => 0, etc.,
13556 and application of the associative law.
13557 NOP_EXPR conversions may be removed freely (as long as we
13558 are careful not to change the type of the overall expression).
13559 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13560 but we can constant-fold them if they have constant operands. */
13562 #ifdef ENABLE_FOLD_CHECKING
13563 # define fold(x) fold_1 (x)
13565 static
13566 #endif
13567 tree
13569 {
13573 tree tem;
13575 /* Return right away if a constant. */
13579 /* CALL_EXPR-like objects with variable numbers of operands are
13580 treated specially. */
13582 {
13584 {
13587 }
13589 }
13592 {
13597 {
13615 }
13616 }
13619 {
13621 {
13628 {
13633 /* Find a matching index by means of a binary search. */
13635 {
13651 else
13653 }
13654 }
13657 }
13665 }
13667 #ifdef ENABLE_FOLD_CHECKING
13668 #undef fold
13674 /* When --enable-checking=fold, compute a digest of expr before
13675 and after actual fold call to see if fold did not accidentally
13676 change original expr. */
13678 tree
13680 {
13681 tree ret;
13684 htab_t ht;
13703 }
13705 void
13707 {
13710 htab_t ht;
13720 }
13722 static void
13724 {
13726 }
13728 static void
13730 {
13736 recursive_label:
13750 {
13751 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13755 }
13762 {
13763 /* Allow these fields to be modified. */
13764 tree tmp;
13772 {
13775 }
13776 }
13785 {
13788 {
13802 }
13806 {
13819 }
13836 {
13842 }
13847 {
13851 }
13862 {
13865 }
13875 }
13876 }
13878 /* Helper function for outputting the checksum of a tree T. When
13879 debugging with gdb, you can "define mynext" to be "next" followed
13880 by "call debug_fold_checksum (op0)", then just trace down till the
13881 outputs differ. */
13883 void
13885 {
13900 }
13902 #endif
13904 /* Fold a unary tree expression with code CODE of type TYPE with an
13905 operand OP0. Return a folded expression if successful. Otherwise,
13906 return a tree expression with code CODE of type TYPE with an
13907 operand OP0. */
13909 tree
13911 {
13912 tree tem;
13913 #ifdef ENABLE_FOLD_CHECKING
13916 htab_t ht;
13923 #endif
13929 #ifdef ENABLE_FOLD_CHECKING
13937 #endif
13939 }
13941 /* Fold a binary tree expression with code CODE of type TYPE with
13942 operands OP0 and OP1. Return a folded expression if successful.
13943 Otherwise, return a tree expression with code CODE of type TYPE
13944 with operands OP0 and OP1. */
13946 tree
13948 MEM_STAT_DECL)
13949 {
13950 tree tem;
13951 #ifdef ENABLE_FOLD_CHECKING
13957 htab_t ht;
13969 #endif
13975 #ifdef ENABLE_FOLD_CHECKING
13991 #endif
13993 }
13995 /* Fold a ternary tree expression with code CODE of type TYPE with
13996 operands OP0, OP1, and OP2. Return a folded expression if
13997 successful. Otherwise, return a tree expression with code CODE of
13998 type TYPE with operands OP0, OP1, and OP2. */
14000 tree
14002 MEM_STAT_DECL)
14003 {
14004 tree tem;
14005 #ifdef ENABLE_FOLD_CHECKING
14013 htab_t ht;
14030 #endif
14037 #ifdef ENABLE_FOLD_CHECKING
14061 #endif
14063 }
14065 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14066 arguments in ARGARRAY, and a null static chain.
14067 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14068 of type TYPE from the given operands as constructed by build_call_array. */
14070 tree
14072 {
14073 tree tem;
14074 #ifdef ENABLE_FOLD_CHECKING
14080 htab_t ht;
14094 #endif
14098 #ifdef ENABLE_FOLD_CHECKING
14115 #endif
14117 }
14119 /* Perform constant folding and related simplification of initializer
14120 expression EXPR. These behave identically to "fold_buildN" but ignore
14121 potential run-time traps and exceptions that fold must preserve. */
14123 #define START_FOLD_INIT \
14124 int saved_signaling_nans = flag_signaling_nans;\
14125 int saved_trapping_math = flag_trapping_math;\
14126 int saved_rounding_math = flag_rounding_math;\
14127 int saved_trapv = flag_trapv;\
14128 int saved_folding_initializer = folding_initializer;\
14129 flag_signaling_nans = 0;\
14130 flag_trapping_math = 0;\
14131 flag_rounding_math = 0;\
14132 flag_trapv = 0;\
14133 folding_initializer = 1;
14135 #define END_FOLD_INIT \
14136 flag_signaling_nans = saved_signaling_nans;\
14137 flag_trapping_math = saved_trapping_math;\
14138 flag_rounding_math = saved_rounding_math;\
14139 flag_trapv = saved_trapv;\
14140 folding_initializer = saved_folding_initializer;
14142 tree
14144 {
14145 tree result;
14146 START_FOLD_INIT;
14150 END_FOLD_INIT;
14152 }
14154 tree
14156 {
14157 tree result;
14158 START_FOLD_INIT;
14162 END_FOLD_INIT;
14164 }
14166 tree
14168 tree op2)
14169 {
14170 tree result;
14171 START_FOLD_INIT;
14175 END_FOLD_INIT;
14177 }
14179 tree
14182 {
14183 tree result;
14184 START_FOLD_INIT;
14188 END_FOLD_INIT;
14190 }
14192 #undef START_FOLD_INIT
14193 #undef END_FOLD_INIT
14195 /* Determine if first argument is a multiple of second argument. Return 0 if
14196 it is not, or we cannot easily determined it to be.
14198 An example of the sort of thing we care about (at this point; this routine
14199 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14200 fold cases do now) is discovering that
14202 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14204 is a multiple of
14206 SAVE_EXPR (J * 8)
14208 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14210 This code also handles discovering that
14212 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14214 is a multiple of 8 so we don't have to worry about dealing with a
14215 possible remainder.
14217 Note that we *look* inside a SAVE_EXPR only to determine how it was
14218 calculated; it is not safe for fold to do much of anything else with the
14219 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14220 at run time. For example, the latter example above *cannot* be implemented
14221 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14222 evaluation time of the original SAVE_EXPR is not necessarily the same at
14223 the time the new expression is evaluated. The only optimization of this
14224 sort that would be valid is changing
14226 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14228 divided by 8 to
14230 SAVE_EXPR (I) * SAVE_EXPR (J)
14232 (where the same SAVE_EXPR (J) is used in the original and the
14233 transformed version). */
14235 int
14237 {
14245 {
14247 /* Bitwise and provides a power of two multiple. If the mask is
14248 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14251 /* FALLTHRU */
14264 {
14268 /* const_binop may not detect overflow correctly,
14269 so check for it explicitly here. */
14275 size_one_node,
14279 }
14283 /* Can't handle conversions from non-integral or wider integral type. */
14289 /* .. fall through ... */
14306 }
14307 }
14309 /* Return true if CODE or TYPE is known to be non-negative. */
14311 static bool
14313 {
14316 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14317 have a signed:1 type (where the value is -1 and 0). */
14320 }
14322 /* Return true if (CODE OP0) is known to be non-negative. If the return
14323 value is based on the assumption that signed overflow is undefined,
14324 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14325 *STRICT_OVERFLOW_P. */
14327 bool
14330 {
14335 {
14337 /* We can't return 1 if flag_wrapv is set because
14338 ABS_EXPR<INT_MIN> = INT_MIN. */
14342 {
14345 }
14352 strict_overflow_p);
14355 {
14360 {
14363 strict_overflow_p);
14365 {
14369 strict_overflow_p);
14370 }
14371 }
14373 {
14376 strict_overflow_p);
14380 }
14381 }
14386 }
14388 /* We don't know sign of `t', so be conservative and return false. */
14390 }
14392 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14393 value is based on the assumption that signed overflow is undefined,
14394 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14395 *STRICT_OVERFLOW_P. */
14397 bool
14400 {
14405 {
14410 strict_overflow_p)
14412 strict_overflow_p));
14414 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14415 both unsigned and at least 2 bits shorter than the result. */
14419 {
14424 {
14428 }
14429 }
14434 {
14435 /* x * x for floating point x is always non-negative. */
14439 strict_overflow_p)
14441 strict_overflow_p));
14442 }
14444 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14445 both unsigned and their total bits is shorter than the result. */
14449 {
14468 {
14478 }
14479 }
14485 strict_overflow_p)
14487 strict_overflow_p));
14498 strict_overflow_p)
14500 strict_overflow_p));
14507 strict_overflow_p);
14510 }
14512 /* We don't know sign of `t', so be conservative and return false. */
14514 }
14516 /* Return true if T is known to be non-negative. If the return
14517 value is based on the assumption that signed overflow is undefined,
14518 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14519 *STRICT_OVERFLOW_P. */
14521 bool
14523 {
14528 {
14540 strict_overflow_p)
14542 strict_overflow_p));
14546 }
14547 /* We don't know sign of `t', so be conservative and return false. */
14549 }
14551 /* Return true if T is known to be non-negative. If the return
14552 value is based on the assumption that signed overflow is undefined,
14553 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14554 *STRICT_OVERFLOW_P. */
14556 bool
14559 {
14562 {
14580 /* Always true. */
14584 /* sqrt(-0.0) is -0.0. */
14588 strict_overflow_p);
14621 /* True if the 1st argument is nonnegative. */
14623 strict_overflow_p);
14626 /* True if the 1st OR 2nd arguments are nonnegative. */
14628 strict_overflow_p)
14630 strict_overflow_p)));
14633 /* True if the 1st AND 2nd arguments are nonnegative. */
14635 strict_overflow_p)
14637 strict_overflow_p)));
14640 /* True if the 2nd argument is nonnegative. */
14642 strict_overflow_p);
14645 /* True if the 1st argument is nonnegative or the second
14646 argument is an even integer. */
14651 strict_overflow_p);
14654 /* True if the 1st argument is nonnegative or the second
14655 argument is an even integer valued real. */
14657 {
14658 REAL_VALUE_TYPE c;
14659 HOST_WIDE_INT n;
14664 {
14665 REAL_VALUE_TYPE cint;
14670 }
14671 }
14673 strict_overflow_p);
14677 }
14679 type);
14680 }
14682 /* Return true if T is known to be non-negative. If the return
14683 value is based on the assumption that signed overflow is undefined,
14684 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14685 *STRICT_OVERFLOW_P. */
14687 bool
14689 {
14695 {
14697 {
14701 /* If the initializer is non-void, then it's a normal expression
14702 that will be assigned to the slot. */
14706 /* Otherwise, the initializer sets the slot in some way. One common
14707 way is an assignment statement at the end of the initializer. */
14709 {
14717 else
14719 }
14723 strict_overflow_p);
14726 }
14729 {
14735 arg0,
14736 arg1,
14737 strict_overflow_p);
14738 }
14742 strict_overflow_p);
14745 strict_overflow_p);
14748 strict_overflow_p);
14753 }
14755 /* We don't know sign of `t', so be conservative and return false. */
14757 }
14759 /* Return true if T is known to be non-negative. If the return
14760 value is based on the assumption that signed overflow is undefined,
14761 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14762 *STRICT_OVERFLOW_P. */
14764 bool
14766 {
14773 {
14780 strict_overflow_p);
14786 strict_overflow_p);
14795 }
14798 {
14806 strict_overflow_p);
14811 strict_overflow_p);
14826 }
14827 }
14829 /* Return true if `t' is known to be non-negative. Handle warnings
14830 about undefined signed overflow. */
14832 bool
14834 {
14841 "determining that expression is always "
14843 WARN_STRICT_OVERFLOW_MISC);
14845 }
14848 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14849 For floating point we further ensure that T is not denormal.
14850 Similar logic is present in nonzero_address in rtlanal.h.
14852 If the return value is based on the assumption that signed overflow
14853 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14854 change *STRICT_OVERFLOW_P. */
14856 bool
14859 {
14861 {
14864 strict_overflow_p);
14867 {
14873 strict_overflow_p));
14874 }
14879 strict_overflow_p);
14883 }
14886 }
14888 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14889 For floating point we further ensure that T is not denormal.
14890 Similar logic is present in nonzero_address in rtlanal.h.
14892 If the return value is based on the assumption that signed overflow
14893 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14894 change *STRICT_OVERFLOW_P. */
14896 bool
14898 tree type,
14899 tree op0,
14901 {
14904 {
14908 {
14909 /* With the presence of negative values it is hard
14910 to say something. */
14917 /* One of operands must be positive and the other non-negative. */
14918 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14919 overflows, on a twos-complement machine the sum of two
14920 nonnegative numbers can never be zero. */
14922 strict_overflow_p)
14924 strict_overflow_p));
14925 }
14930 {
14932 strict_overflow_p)
14934 strict_overflow_p))
14935 {
14938 }
14939 }
14948 {
14951 }
14958 {
14962 /* When both operands are nonzero, then MAX must be too. */
14964 strict_overflow_p))
14967 /* MAX where operand 0 is positive is positive. */
14969 strict_overflow_p);
14970 }
14971 /* MAX where operand 1 is positive is positive. */
14976 {
14980 }
14985 strict_overflow_p)
14987 strict_overflow_p));
14991 }
14994 }
14996 /* Return true when T is an address and is known to be nonzero.
14997 For floating point we further ensure that T is not denormal.
14998 Similar logic is present in nonzero_address in rtlanal.h.
15000 If the return value is based on the assumption that signed overflow
15001 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15002 change *STRICT_OVERFLOW_P. */
15004 bool
15006 {
15009 {
15014 {
15020 /* Weak declarations may link to NULL. Other things may also be NULL
15021 so protect with -fdelete-null-pointer-checks; but not variables
15022 allocated on the stack. */
15024 && (flag_delete_null_pointer_checks
15028 /* Constants are never weak. */
15033 }
15041 {
15045 }
15050 }
15052 }
15054 /* Return true when T is an address and is known to be nonzero.
15055 For floating point we further ensure that T is not denormal.
15056 Similar logic is present in nonzero_address in rtlanal.h.
15058 If the return value is based on the assumption that signed overflow
15059 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15060 change *STRICT_OVERFLOW_P. */
15062 bool
15064 {
15068 /* Doing something useful for floating point would need more work. */
15074 {
15077 strict_overflow_p);
15083 strict_overflow_p);
15091 }
15094 {
15097 strict_overflow_p);
15105 strict_overflow_p);
15122 strict_overflow_p);
15126 strict_overflow_p);
15133 }
15135 }
15137 /* Return true when T is an address and is known to be nonzero.
15138 Handle warnings about undefined signed overflow. */
15140 bool
15142 {
15149 "determining that expression is always "
15151 WARN_STRICT_OVERFLOW_MISC);
15153 }
15155 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15156 attempt to fold the expression to a constant without modifying TYPE,
15157 OP0 or OP1.
15159 If the expression could be simplified to a constant, then return
15160 the constant. If the expression would not be simplified to a
15161 constant, then return NULL_TREE. */
15163 tree
15165 {
15168 }
15170 /* Given the components of a unary expression CODE, TYPE and OP0,
15171 attempt to fold the expression to a constant without modifying
15172 TYPE or OP0.
15174 If the expression could be simplified to a constant, then return
15175 the constant. If the expression would not be simplified to a
15176 constant, then return NULL_TREE. */
15178 tree
15180 {
15183 }
15185 /* If EXP represents referencing an element in a constant string
15186 (either via pointer arithmetic or array indexing), return the
15187 tree representing the value accessed, otherwise return NULL. */
15189 tree
15191 {
15195 {
15197 tree index;
15198 tree string;
15202 else
15203 {
15207 /* Optimize the special-case of a zero lower bound.
15209 We convert the low_bound to sizetype to avoid some problems
15210 with constant folding. (E.g. suppose the lower bound is 1,
15211 and its mode is QI. Without the conversion,l (ARRAY
15212 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15213 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15218 }
15231 }
15233 }
15235 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15236 an integer constant, real, or fixed-point constant.
15238 TYPE is the type of the result. */
15240 static tree
15242 {
15246 {
15248 {
15250 HOST_WIDE_INT high;
15258 }
15265 {
15266 FIXED_VALUE_TYPE f;
15271 /* Propagate overflow flags. */
15275 }
15279 }
15282 }
15284 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15285 an integer constant or real constant.
15287 TYPE is the type of the result. */
15289 tree
15291 {
15295 {
15297 /* If the value is unsigned, then the absolute value is
15298 the same as the ordinary value. */
15301 /* Similarly, if the value is non-negative. */
15304 /* If the value is negative, then the absolute value is
15305 its negation. */
15306 else
15307 {
15309 HOST_WIDE_INT high;
15315 }
15321 else
15327 }
15330 }
15332 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15333 constant. TYPE is the type of the result. */
15335 static tree
15337 {
15347 }
15349 /* Given CODE, a relational operator, the target type, TYPE and two
15350 constant operands OP0 and OP1, return the result of the
15351 relational operation. If the result is not a compile time
15352 constant, then return NULL_TREE. */
15354 static tree
15356 {
15359 /* From here on, the only cases we handle are when the result is
15360 known to be a constant. */
15363 {
15367 /* Handle the cases where either operand is a NaN. */
15369 {
15371 {
15399 }
15402 }
15405 }
15408 {
15412 }
15414 /* Handle equality/inequality of complex constants. */
15416 {
15427 else
15429 }
15431 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15433 To compute GT, swap the arguments and do LT.
15434 To compute GE, do LT and invert the result.
15435 To compute LE, swap the arguments, do LT and invert the result.
15436 To compute NE, do EQ and invert the result.
15438 Therefore, the code below must handle only EQ and LT. */
15441 {
15446 }
15448 /* Note that it is safe to invert for real values here because we
15449 have already handled the one case that it matters. */
15453 {
15456 }
15458 /* Compute a result for LT or EQ if args permit;
15459 Otherwise return T. */
15461 {
15466 else
15468 }
15469 else
15475 }
15477 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15478 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15479 itself. */
15481 tree
15483 {
15484 /* If the expression does not have side effects then we don't have to wrap
15485 it with a cleanup point expression. */
15489 /* If the expression is a return, check to see if the expression inside the
15490 return has no side effects or the right hand side of the modify expression
15491 inside the return. If either don't have side effects set we don't need to
15492 wrap the expression in a cleanup point expression. Note we don't check the
15493 left hand side of the modify because it should always be a return decl. */
15495 {
15502 }
15505 }
15507 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15508 of an indirection through OP0, or NULL_TREE if no simplification is
15509 possible. */
15511 tree
15513 {
15515 tree subtype;
15523 {
15526 /* *&CONST_DECL -> to the value of the const decl. */
15529 /* *&p => p; make sure to handle *&"str"[cst] here. */
15531 {
15535 else
15537 }
15538 /* *(foo *)&fooarray => fooarray[0] */
15541 {
15547 }
15548 /* *(foo *)&complexfoo => __real__ complexfoo */
15552 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15555 {
15559 }
15560 }
15562 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15565 {
15568 tree op00type;
15575 {
15586 }
15587 }
15590 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15593 {
15596 tree op00type;
15603 {
15607 }
15608 }
15610 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15613 {
15614 tree type_domain;
15621 }
15624 }
15626 /* Builds an expression for an indirection through T, simplifying some
15627 cases. */
15629 tree
15631 {
15637 else
15639 }
15641 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15643 tree
15645 {
15650 else
15652 }
15654 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15655 whose result is ignored. The type of the returned tree need not be
15656 the same as the original expression. */
15658 tree
15660 {
15666 {
15677 else
15683 {
15699 }
15704 }
15705 }
15707 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15708 This can only be applied to objects of a sizetype. */
15710 tree
15712 {
15719 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15720 have to do anything. Only do this when we are not given a const,
15721 because in that case, this check is more expensive than just
15722 doing it. */
15724 {
15729 }
15731 /* If divisor is a power of two, simplify this to bit manipulation. */
15733 {
15735 {
15748 {
15749 high++;
15752 }
15756 }
15757 else
15758 {
15759 tree t;
15765 }
15766 }
15767 else
15768 {
15773 }
15776 }
15778 /* Likewise, but round down. */
15780 tree
15782 {
15789 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15790 have to do anything. Only do this when we are not given a const,
15791 because in that case, this check is more expensive than just
15792 doing it. */
15794 {
15799 }
15801 /* If divisor is a power of two, simplify this to bit manipulation. */
15803 {
15804 tree t;
15808 }
15809 else
15810 {
15815 }
15818 }
15820 /* Returns the pointer to the base of the object addressed by EXP and
15821 extracts the information about the offset of the access, storing it
15822 to PBITPOS and POFFSET. */
15824 static tree
15827 {
15828 tree core;
15831 HOST_WIDE_INT bitsize;
15834 {
15839 }
15840 else
15841 {
15845 }
15848 }
15850 /* Returns true if addresses of E1 and E2 differ by a constant, false
15851 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15853 bool
15855 {
15869 {
15879 }
15881 {
15882 /* If only one of the offsets is non-constant, the difference cannot
15883 be a constant. */
15885 }
15886 else
15891 }
15893 /* Simplify the floating point expression EXP when the sign of the
15894 result is not significant. Return NULL_TREE if no simplification
15895 is possible. */
15897 tree
15899 {
15903 {
15938 {
15941 {
15943 /* Strip copysign function call, return the 1st argument. */
15949 /* Strip sign ops from the argument of "odd" math functions. */
15951 {
15955 }
15957 }
15958 }
15963 }
15965 }