| blob | 782a30200ce96ec257aca585b7ca9dbab341fdd7 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 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.
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 takes a constant, an overflowable flag and prior
43 overflow indicators. It forces the value to fit the type and sets
44 TREE_OVERFLOW and TREE_CONSTANT_OVERFLOW as appropriate. */
63 /* Non-zero if we are folding constants inside an initializer; zero
64 otherwise. */
67 /* The following constants represent a bit based encoding of GCC's
68 comparison operators. This encoding simplifies transformations
69 on relational comparison operators, such as AND and OR. */
87 };
121 tree);
146 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
147 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
148 and SUM1. Then this yields nonzero if overflow occurred during the
149 addition.
151 Overflow occurs if A and B have the same sign, but A and SUM differ in
152 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
153 sign. */
154 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
155 \f
156 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
157 We do that by representing the two-word integer in 4 words, with only
158 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
159 number. The value of the word is LOWPART + HIGHPART * BASE. */
161 #define LOWPART(x) \
162 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
163 #define HIGHPART(x) \
164 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
165 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
167 /* Unpack a two-word integer into 4 words.
168 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
169 WORDS points to the array of HOST_WIDE_INTs. */
171 static void
173 {
178 }
180 /* Pack an array of 4 words into a two-word integer.
181 WORDS points to the array of words.
182 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
184 static void
187 {
190 }
191 \f
192 /* T is an INT_CST node. OVERFLOWABLE indicates if we are interested
193 in overflow of the value, when >0 we are only interested in signed
194 overflow, for <0 we are interested in any overflow. OVERFLOWED
195 indicates whether overflow has already occurred. CONST_OVERFLOWED
196 indicates whether constant overflow has already occurred. We force
197 T's value to be within range of T's type (by setting to 0 or 1 all
198 the bits outside the type's range). We set TREE_OVERFLOWED if,
199 OVERFLOWED is nonzero,
200 or OVERFLOWABLE is >0 and signed overflow occurs
201 or OVERFLOWABLE is <0 and any overflow occurs
202 We set TREE_CONSTANT_OVERFLOWED if,
203 CONST_OVERFLOWED is nonzero
204 or we set TREE_OVERFLOWED.
205 We return either the original T, or a copy. */
207 tree
210 {
212 HOST_WIDE_INT high;
224 else
226 /* Size types *are* sign extended. */
231 /* First clear all bits that are beyond the type's precision. */
234 ;
237 else
238 {
242 }
249 {
250 /* Sign extend top half? */
254 }
256 {
259 }
260 else
261 {
262 /* Sign extend bottom half? */
264 {
267 }
268 }
270 /* If the value changed, return a new node. */
273 {
279 {
283 }
285 {
288 }
289 }
292 }
293 \f
294 /* Add two doubleword integers with doubleword result.
295 Return nonzero if the operation overflows according to UNSIGNED_P.
296 Each argument is given as two `HOST_WIDE_INT' pieces.
297 One argument is L1 and H1; the other, L2 and H2.
298 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
300 int
305 {
307 HOST_WIDE_INT h;
317 else
319 }
321 /* Negate a doubleword integer with doubleword result.
322 Return nonzero if the operation overflows, assuming it's signed.
323 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
324 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
326 int
329 {
331 {
335 }
336 else
337 {
341 }
342 }
343 \f
344 /* Multiply two doubleword integers with doubleword result.
345 Return nonzero if the operation overflows according to UNSIGNED_P.
346 Each argument is given as two `HOST_WIDE_INT' pieces.
347 One argument is L1 and H1; the other, L2 and H2.
348 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
350 int
355 {
370 {
373 {
375 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
377 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
381 }
383 }
388 /* Unsigned overflow is immediate. */
392 /* Check for signed overflow by calculating the signed representation of the
393 top half of the result; it should agree with the low half's sign bit. */
395 {
398 }
400 {
403 }
405 }
406 \f
407 /* Shift the doubleword integer in L1, H1 left by COUNT places
408 keeping only PREC bits of result.
409 Shift right if COUNT is negative.
410 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
411 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
413 void
417 {
421 {
424 }
430 {
431 /* Shifting by the host word size is undefined according to the
432 ANSI standard, so we must handle this as a special case. */
435 }
437 {
440 }
441 else
442 {
446 }
448 /* Sign extend all bits that are beyond the precision. */
456 ;
458 {
461 }
462 else
463 {
467 }
468 }
470 /* Shift the doubleword integer in L1, H1 right by COUNT places
471 keeping only PREC bits of result. COUNT must be positive.
472 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
473 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
475 void
480 {
483 signmask = (arith
491 {
492 /* Shifting by the host word size is undefined according to the
493 ANSI standard, so we must handle this as a special case. */
496 }
498 {
501 }
502 else
503 {
507 }
509 /* Zero / sign extend all bits that are beyond the precision. */
512 {
515 }
517 ;
519 {
522 }
523 else
524 {
528 }
529 }
530 \f
531 /* Rotate the doubleword integer in L1, H1 left by COUNT places
532 keeping only PREC bits of result.
533 Rotate right if COUNT is negative.
534 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
536 void
540 {
552 }
554 /* Rotate the doubleword integer in L1, H1 left by COUNT places
555 keeping only PREC bits of result. COUNT must be positive.
556 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
558 void
562 {
574 }
575 \f
576 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
577 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
578 CODE is a tree code for a kind of division, one of
579 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
580 or EXACT_DIV_EXPR
581 It controls how the quotient is rounded to an integer.
582 Return nonzero if the operation overflows.
583 UNS nonzero says do unsigned division. */
585 int
588 HOST_WIDE_INT hnum_orig,
590 HOST_WIDE_INT hden_orig,
594 {
610 /* Calculate quotient sign and convert operands to unsigned. */
612 {
614 {
616 /* (minimum integer) / (-1) is the only overflow case. */
620 }
622 {
625 }
626 }
631 /* This unsigned division rounds toward zero. */
634 }
638 /* hden != 0 already checked. */
643 }
653 /* Special code for when the divisor < BASE. */
655 {
656 /* hnum != 0 already checked. */
658 {
662 }
663 }
664 else
665 {
666 /* Full double precision division,
667 with thanks to Don Knuth's "Seminumerical Algorithms". */
671 /* Find the highest nonzero divisor digit. */
674 {
677 }
679 /* Insure that the first digit of the divisor is at least BASE/2.
680 This is required by the quotient digit estimation algorithm. */
687 {
691 }
696 {
701 }
702 }
706 /* Main loop */
708 {
709 /* Guess the next quotient digit, quo_est, by dividing the first
710 two remaining dividend digits by the high order quotient digit.
711 quo_est is never low and is at most 2 high. */
718 else
721 /* Refine quo_est so it's usually correct, and at most one high. */
726 quo_est--;
728 /* Try QUO_EST as the quotient digit, by multiplying the
729 divisor by QUO_EST and subtracting from the remaining dividend.
730 Keep in mind that QUO_EST is the I - 1st digit. */
734 {
740 }
742 /* If quo_est was high by one, then num[i] went negative and
743 we need to correct things. */
745 {
746 quo_est--;
749 {
753 }
756 }
758 /* Store the quotient digit. */
760 }
761 }
765 finish_up:
766 /* If result is negative, make it so. */
770 /* Compute trial remainder: rem = num - (quo * den) */
776 {
785 {
786 /* quo = quo - 1; */
789 }
790 else
797 {
800 }
801 else
807 {
813 /* Get absolute values. */
819 /* If (2 * abs (lrem) >= abs (lden)) */
828 {
830 /* quo = quo - 1; */
833 else
834 /* quo = quo + 1; */
837 }
838 else
840 }
845 }
847 /* Compute true remainder: rem = num - (quo * den) */
852 }
854 /* If ARG2 divides ARG1 with zero remainder, carries out the division
855 of type CODE and returns the quotient.
856 Otherwise returns NULL_TREE. */
858 static tree
860 {
879 }
880 \f
881 /* This is non-zero if we should defer warnings about undefined
882 overflow. This facility exists because these warnings are a
883 special case. The code to estimate loop iterations does not want
884 to issue any warnings, since it works with expressions which do not
885 occur in user code. Various bits of cleanup code call fold(), but
886 only use the result if it has certain characteristics (e.g., is a
887 constant); that code only wants to issue a warning if the result is
888 used. */
892 /* If a warning about undefined overflow is deferred, this is the
893 warning. Note that this may cause us to turn two warnings into
894 one, but that is fine since it is sufficient to only give one
895 warning per expression. */
899 /* If a warning about undefined overflow is deferred, this is the
900 level at which the warning should be emitted. */
904 /* Start deferring overflow warnings. We could use a stack here to
905 permit nested calls, but at present it is not necessary. */
907 void
909 {
911 }
913 /* Stop deferring overflow warnings. If there is a pending warning,
914 and ISSUE is true, then issue the warning if appropriate. STMT is
915 the statement with which the warning should be associated (used for
916 location information); STMT may be NULL. CODE is the level of the
917 warning--a warn_strict_overflow_code value. This function will use
918 the smaller of CODE and the deferred code when deciding whether to
919 issue the warning. CODE may be zero to mean to always use the
920 deferred code. */
922 void
924 {
926 location_t locus;
931 {
937 }
945 /* Use the smallest code level when deciding to issue the
946 warning. */
955 else
958 }
960 /* Stop deferring overflow warnings, ignoring any deferred
961 warnings. */
963 void
965 {
967 }
969 /* Whether we are deferring overflow warnings. */
971 bool
973 {
975 }
977 /* This is called when we fold something based on the fact that signed
978 overflow is undefined. */
980 static void
982 {
985 {
988 {
991 }
992 }
995 }
996 \f
997 /* Return true if the built-in mathematical function specified by CODE
998 is odd, i.e. -f(x) == f(-x). */
1000 static bool
1002 {
1004 {
1018 }
1020 }
1022 /* Check whether we may negate an integer constant T without causing
1023 overflow. */
1025 bool
1027 {
1030 tree type;
1040 {
1045 }
1046 else
1051 }
1053 /* Determine whether an expression T can be cheaply negated using
1054 the function negate_expr without introducing undefined overflow. */
1056 static bool
1058 {
1059 tree type;
1068 {
1073 /* Check that -CST will not overflow type. */
1090 /* -(A + B) -> (-B) - A. */
1095 /* -(A + B) -> (-A) - B. */
1099 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1108 /* Fall through. */
1121 /* In general we can't negate A / B, because if A is INT_MIN and
1122 B is 1, we may turn this into INT_MIN / -1 which is undefined
1123 and actually traps on some architectures. But if overflow is
1124 undefined, we can negate, because - (INT_MIN / 1) is an
1125 overflow. */
1133 /* Negate -((double)float) as (double)(-float). */
1135 {
1139 }
1143 /* Negate -f(x) as f(-x). */
1149 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1151 {
1157 }
1162 }
1164 }
1166 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1167 simplification is possible.
1168 If negate_expr_p would return true for T, NULL_TREE will never be
1169 returned. */
1171 static tree
1173 {
1175 tree tem;
1178 {
1179 /* Convert - (~A) to A + 1. */
1195 /* Two's complement FP formats, such as c4x, may overflow. */
1201 {
1210 }
1218 {
1219 /* -(A + B) -> (-B) - A. */
1223 {
1227 }
1229 /* -(A + B) -> (-A) - B. */
1231 {
1235 }
1236 }
1240 /* - (A - B) -> B - A */
1251 /* Fall through. */
1255 {
1264 }
1272 /* In general we can't negate A / B, because if A is INT_MIN and
1273 B is 1, we may turn this into INT_MIN / -1 which is undefined
1274 and actually traps on some architectures. But if overflow is
1275 undefined, we can negate, because - (INT_MIN / 1) is an
1276 overflow. */
1278 {
1283 {
1290 }
1293 {
1300 }
1301 }
1305 /* Convert -((double)float) into (double)(-float). */
1307 {
1311 }
1315 /* Negate -f(x) as f(-x). */
1318 {
1325 }
1329 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1331 {
1336 {
1343 }
1344 }
1349 }
1352 }
1354 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1355 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1356 return NULL_TREE. */
1358 static tree
1360 {
1373 }
1374 \f
1375 /* Split a tree IN into a constant, literal and variable parts that could be
1376 combined with CODE to make IN. "constant" means an expression with
1377 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1378 commutative arithmetic operation. Store the constant part into *CONP,
1379 the literal in *LITP and return the variable part. If a part isn't
1380 present, set it to null. If the tree does not decompose in this way,
1381 return the entire tree as the variable part and the other parts as null.
1383 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1384 case, we negate an operand that was subtracted. Except if it is a
1385 literal for which we use *MINUS_LITP instead.
1387 If NEGATE_P is true, we are negating all of IN, again except a literal
1388 for which we use *MINUS_LITP instead.
1390 If IN is itself a literal or constant, return it as appropriate.
1392 Note that we do not guarantee that any of the three values will be the
1393 same type as IN, but they will have the same signedness and mode. */
1395 static tree
1398 {
1405 /* Strip any conversions that don't change the machine mode or signedness. */
1412 /* We can associate addition and subtraction together (even
1413 though the C standard doesn't say so) for integers because
1414 the value is not affected. For reals, the value might be
1415 affected, so we can't. */
1418 {
1424 /* First see if either of the operands is a literal, then a constant. */
1435 /* If we haven't dealt with either operand, this is not a case we can
1436 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1441 else
1444 /* Now do any needed negations. */
1451 }
1454 else
1458 {
1465 }
1468 }
1470 /* Re-associate trees split by the above function. T1 and T2 are either
1471 expressions to associate or null. Return the new expression, if any. If
1472 we build an operation, do it in TYPE and with CODE. */
1474 static tree
1476 {
1482 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1483 try to fold this since we will have infinite recursion. But do
1484 deal with any NEGATE_EXPRs. */
1487 {
1489 {
1498 }
1500 {
1503 }
1507 }
1511 }
1512 \f
1513 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1514 to produce a new constant. Return NULL_TREE if we don't know how
1515 to evaluate CODE at compile-time.
1517 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1519 tree
1521 {
1525 HOST_WIDE_INT hi;
1527 HOST_WIDE_INT garbageh;
1528 tree t;
1531 int is_sizetype
1541 {
1557 /* It's unclear from the C standard whether shifts can overflow.
1558 The following code ignores overflow; perhaps a C standard
1559 interpretation ruling is needed. */
1588 /* This is a shortcut for a common special case. */
1593 {
1599 }
1601 /* ... fall through ... */
1607 {
1610 }
1613 {
1616 }
1623 /* This is a shortcut for a common special case. */
1628 {
1633 }
1635 /* ... fall through ... */
1653 else
1659 else
1665 }
1670 {
1671 /* Propagate overflow flags ourselves. */
1674 {
1678 }
1680 {
1683 }
1684 }
1685 else
1693 }
1695 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1696 constant. We assume ARG1 and ARG2 have the same data type, or at least
1697 are the same kind of constant and the same machine mode. Return zero if
1698 combining the constants is not allowed in the current operating mode.
1700 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1702 static tree
1704 {
1705 /* Sanity check for the recursive cases. */
1716 {
1718 REAL_VALUE_TYPE d1;
1719 REAL_VALUE_TYPE d2;
1720 REAL_VALUE_TYPE value;
1721 REAL_VALUE_TYPE result;
1725 /* The following codes are handled by real_arithmetic. */
1727 {
1738 }
1746 /* Don't perform operation if we honor signaling NaNs and
1747 either operand is a NaN. */
1752 /* Don't perform operation if it would raise a division
1753 by zero exception. */
1759 /* If either operand is a NaN, just return it. Otherwise, set up
1760 for floating-point trap; we return an overflow. */
1769 /* Don't constant fold this floating point operation if
1770 the result has overflowed and flag_trapping_math. */
1778 /* Don't constant fold this floating point operation if the
1779 result may dependent upon the run-time rounding mode and
1780 flag_rounding_math is set, or if GCC's software emulation
1781 is unable to accurately represent the result. */
1796 }
1799 {
1808 {
1819 notrunc);
1823 notrunc);
1827 {
1828 tree magsquared
1832 notrunc);
1833 tree t1
1837 notrunc);
1838 tree t2
1842 notrunc);
1849 }
1854 }
1858 }
1861 }
1863 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1864 indicates which particular sizetype to create. */
1866 tree
1868 {
1870 }
1871 \f
1872 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1873 is a tree code. The type of the result is taken from the operands.
1874 Both must be the same type integer type and it must be a size type.
1875 If the operands are constant, so is the result. */
1877 tree
1879 {
1888 /* Handle the special case of two integer constants faster. */
1890 {
1891 /* And some specific cases even faster than that. */
1900 /* Handle general case of two integer constants. */
1902 }
1905 }
1907 /* Given two values, either both of sizetype or both of bitsizetype,
1908 compute the difference between the two values. Return the value
1909 in signed type corresponding to the type of the operands. */
1911 tree
1913 {
1915 tree ctype;
1920 /* If the type is already signed, just do the simple thing. */
1926 /* If either operand is not a constant, do the conversions to the signed
1927 type and subtract. The hardware will do the right thing with any
1928 overflow in the subtraction. */
1933 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1934 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1935 overflow) and negate (which can't either). Special-case a result
1936 of zero while we're here. */
1941 else
1945 }
1946 \f
1947 /* A subroutine of fold_convert_const handling conversions of an
1948 INTEGER_CST to another integer type. */
1950 static tree
1952 {
1953 tree t;
1955 /* Given an integer constant, make new constant with new type,
1956 appropriately sign-extended or truncated. */
1961 /* Don't set the overflow when
1962 converting a pointer */
1971 }
1973 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1974 to an integer type. */
1976 static tree
1978 {
1980 tree t;
1982 /* The following code implements the floating point to integer
1983 conversion rules required by the Java Language Specification,
1984 that IEEE NaNs are mapped to zero and values that overflow
1985 the target precision saturate, i.e. values greater than
1986 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1987 are mapped to INT_MIN. These semantics are allowed by the
1988 C and C++ standards that simply state that the behavior of
1989 FP-to-integer conversion is unspecified upon overflow. */
1992 REAL_VALUE_TYPE r;
1996 {
2015 }
2017 /* If R is NaN, return zero and show we have an overflow. */
2019 {
2023 }
2025 /* See if R is less than the lower bound or greater than the
2026 upper bound. */
2029 {
2033 {
2037 }
2038 }
2041 {
2044 {
2047 {
2051 }
2052 }
2053 }
2063 }
2065 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2066 to another floating point type. */
2068 static tree
2070 {
2071 REAL_VALUE_TYPE value;
2072 tree t;
2081 }
2083 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2084 type TYPE. If no simplification can be done return NULL_TREE. */
2086 static tree
2088 {
2093 {
2098 }
2100 {
2105 }
2107 }
2109 /* Construct a vector of zero elements of vector type TYPE. */
2111 static tree
2113 {
2124 }
2126 /* Convert expression ARG to type TYPE. Used by the middle-end for
2127 simple conversions in preference to calling the front-end's convert. */
2129 tree
2131 {
2133 tree tem;
2149 {
2154 {
2158 }
2163 {
2166 }
2173 {
2177 }
2179 {
2183 }
2186 {
2201 }
2205 {
2214 {
2218 {
2222 }
2230 }
2234 }
2249 }
2250 }
2251 \f
2252 /* Return false if expr can be assumed not to be an lvalue, true
2253 otherwise. */
2255 static bool
2257 {
2258 /* We only need to wrap lvalue tree codes. */
2260 {
2294 /* Assume the worst for front-end tree codes. */
2298 }
2301 }
2303 /* Return an expr equal to X but certainly not valid as an lvalue. */
2305 tree
2307 {
2308 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2309 us. */
2316 }
2318 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2319 Zero means allow extended lvalues. */
2323 /* When pedantic, return an expr equal to X but certainly not valid as a
2324 pedantic lvalue. Otherwise, return X. */
2326 static tree
2328 {
2331 else
2333 }
2334 \f
2335 /* Given a tree comparison code, return the code that is the logical inverse
2336 of the given code. It is not safe to do this for floating-point
2337 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2338 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2340 enum tree_code
2342 {
2347 {
2378 }
2379 }
2381 /* Similar, but return the comparison that results if the operands are
2382 swapped. This is safe for floating-point. */
2384 enum tree_code
2386 {
2388 {
2414 }
2415 }
2418 /* Convert a comparison tree code from an enum tree_code representation
2419 into a compcode bit-based encoding. This function is the inverse of
2420 compcode_to_comparison. */
2422 static enum comparison_code
2424 {
2426 {
2457 }
2458 }
2460 /* Convert a compcode bit-based encoding of a comparison operator back
2461 to GCC's enum tree_code representation. This function is the
2462 inverse of comparison_to_compcode. */
2464 static enum tree_code
2466 {
2468 {
2499 }
2500 }
2502 /* Return a tree for the comparison which is the combination of
2503 doing the AND or OR (depending on CODE) of the two operations LCODE
2504 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2505 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2506 if this makes the transformation invalid. */
2508 tree
2512 {
2519 {
2530 }
2533 {
2534 /* Eliminate unordered comparisons, as well as LTGT and ORD
2535 which are not used unless the mode has NaNs. */
2541 }
2543 {
2544 /* Check that the original operation and the optimized ones will trap
2545 under the same condition. */
2556 /* In a short-circuited boolean expression the LHS might be
2557 such that the RHS, if evaluated, will never trap. For
2558 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2559 if neither x nor y is NaN. (This is a mixed blessing: for
2560 example, the expression above will never trap, hence
2561 optimizing it to x < y would be invalid). */
2566 /* If the comparison was short-circuited, and only the RHS
2567 trapped, we may now generate a spurious trap. */
2572 /* If we changed the conditions that cause a trap, we lose. */
2575 }
2581 else
2584 }
2586 /* Return nonzero if CODE is a tree code that represents a truth value. */
2588 static int
2590 {
2595 }
2596 \f
2597 /* Return nonzero if two operands (typically of the same tree node)
2598 are necessarily equal. If either argument has side-effects this
2599 function returns zero. FLAGS modifies behavior as follows:
2601 If OEP_ONLY_CONST is set, only return nonzero for constants.
2602 This function tests whether the operands are indistinguishable;
2603 it does not test whether they are equal using C's == operation.
2604 The distinction is important for IEEE floating point, because
2605 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2606 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2608 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2609 even though it may hold multiple values during a function.
2610 This is because a GCC tree node guarantees that nothing else is
2611 executed between the evaluation of its "operands" (which may often
2612 be evaluated in arbitrary order). Hence if the operands themselves
2613 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2614 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2615 unset means assuming isochronic (or instantaneous) tree equivalence.
2616 Unless comparing arbitrary expression trees, such as from different
2617 statements, this flag can usually be left unset.
2619 If OEP_PURE_SAME is set, then pure functions with identical arguments
2620 are considered the same. It is used when the caller has other ways
2621 to ensure that global memory is unchanged in between. */
2623 int
2625 {
2626 /* If either is ERROR_MARK, they aren't equal. */
2630 /* If both types don't have the same signedness, then we can't consider
2631 them equal. We must check this before the STRIP_NOPS calls
2632 because they may change the signedness of the arguments. */
2636 /* If both types don't have the same precision, then it is not safe
2637 to strip NOPs. */
2644 /* In case both args are comparisons but with different comparison
2645 code, try to swap the comparison operands of one arg to produce
2646 a match and compare that variant. */
2650 {
2658 }
2661 /* This is needed for conversions and for COMPONENT_REF.
2662 Might as well play it safe and always test this. */
2668 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2669 We don't care about side effects in that case because the SAVE_EXPR
2670 takes care of that for us. In all other cases, two expressions are
2671 equal if they have no side effects. If we have two identical
2672 expressions with side effects that should be treated the same due
2673 to the only side effects being identical SAVE_EXPR's, that will
2674 be detected in the recursive calls below. */
2680 /* Next handle constant cases, those for which we can return 1 even
2681 if ONLY_CONST is set. */
2684 {
2697 {
2707 {
2709 flags))
2713 }
2716 }
2720 flags)
2722 flags));
2735 }
2740 /* Define macros to test an operand from arg0 and arg1 for equality and a
2741 variant that allows null and views null as being different from any
2742 non-null value. In the latter case, if either is null, the both
2743 must be; otherwise, do the normal comparison. */
2744 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2745 TREE_OPERAND (arg1, N), flags)
2747 #define OP_SAME_WITH_NULL(N) \
2748 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2749 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2752 {
2754 /* Two conversions are equal only if signedness and modes match. */
2756 {
2769 }
2779 /* For commutative ops, allow the other order. */
2787 /* If either of the pointer (or reference) expressions we are
2788 dereferencing contain a side effect, these cannot be equal. */
2794 {
2804 /* Operands 2 and 3 may be null. */
2811 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2812 may be NULL when we're called to compare MEM_EXPRs. */
2822 }
2826 {
2841 /* Otherwise take into account this is a commutative operation. */
2848 /* If the CALL_EXPRs call different functions, then they
2849 clearly can not be equal. */
2853 {
2857 else
2861 }
2863 /* Now see if all the arguments are the same. operand_equal_p
2864 does not handle TREE_LIST, so we walk the operands here
2865 feeding them to operand_equal_p. */
2869 {
2871 flags))
2876 }
2878 /* If we get here and both argument lists are exhausted
2879 then the CALL_EXPRs are equal. */
2884 }
2887 /* Consider __builtin_sqrt equal to sqrt. */
2895 }
2897 #undef OP_SAME
2898 #undef OP_SAME_WITH_NULL
2899 }
2900 \f
2901 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2902 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2904 When in doubt, return 0. */
2906 static int
2908 {
2920 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2921 and see if the inner values are the same. This removes any
2922 signedness comparison, which doesn't matter here. */
2929 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2930 actual comparison operand, ARG0.
2932 First throw away any conversions to wider types
2933 already present in the operands. */
2942 {
2945 /* Make sure shorter operand is extended the right way
2946 to match the longer operand. */
2952 }
2955 }
2956 \f
2957 /* See if ARG is an expression that is either a comparison or is performing
2958 arithmetic on comparisons. The comparisons must only be comparing
2959 two different values, which will be stored in *CVAL1 and *CVAL2; if
2960 they are nonzero it means that some operands have already been found.
2961 No variables may be used anywhere else in the expression except in the
2962 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2963 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2965 If this is true, return 1. Otherwise, return zero. */
2967 static int
2969 {
2973 /* We can handle some of the tcc_expression cases here. */
2983 {
2984 /* If we've already found a CVAL1 or CVAL2, this expression is
2985 two complex to handle. */
2991 }
2994 {
3017 /* First see if we can handle the first operand, then the second. For
3018 the second operand, we know *CVAL1 can't be zero. It must be that
3019 one side of the comparison is each of the values; test for the
3020 case where this isn't true by failing if the two operands
3021 are the same. */
3030 ;
3034 ;
3035 else
3039 ;
3043 ;
3044 else
3051 }
3052 }
3053 \f
3054 /* ARG is a tree that is known to contain just arithmetic operations and
3055 comparisons. Evaluate the operations in the tree substituting NEW0 for
3056 any occurrence of OLD0 as an operand of a comparison and likewise for
3057 NEW1 and OLD1. */
3059 static tree
3061 {
3066 /* We can handle some of the tcc_expression cases here. */
3074 {
3089 {
3106 }
3107 /* Fall through - ??? */
3110 {
3114 /* We need to check both for exact equality and tree equality. The
3115 former will be true if the operand has a side-effect. In that
3116 case, we know the operand occurred exactly once. */
3129 }
3133 }
3134 }
3135 \f
3136 /* Return a tree for the case when the result of an expression is RESULT
3137 converted to TYPE and OMITTED was previously an operand of the expression
3138 but is now not needed (e.g., we folded OMITTED * 0).
3140 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3141 the conversion of RESULT to TYPE. */
3143 tree
3145 {
3152 }
3154 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3156 static tree
3158 {
3165 }
3167 /* Return a tree for the case when the result of an expression is RESULT
3168 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3169 of the expression but are now not needed.
3171 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3172 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3173 evaluated before OMITTED2. Otherwise, if neither has side effects,
3174 just do the conversion of RESULT to TYPE. */
3176 tree
3178 {
3187 }
3189 \f
3190 /* Return a simplified tree node for the truth-negation of ARG. This
3191 never alters ARG itself. We assume that ARG is an operation that
3192 returns a truth value (0 or 1).
3194 FIXME: one would think we would fold the result, but it causes
3195 problems with the dominator optimizer. */
3197 tree
3199 {
3203 /* If this is a comparison, we can simply invert it, except for
3204 floating-point non-equality comparisons, in which case we just
3205 enclose a TRUTH_NOT_EXPR around what we have. */
3208 {
3211 && flag_trapping_math
3215 else
3216 {
3221 else
3224 }
3225 }
3228 {
3243 /* Here we can invert either operand. We invert the first operand
3244 unless the second operand is a TRUTH_NOT_EXPR in which case our
3245 result is the XOR of the first operand with the inside of the
3246 negation of the second operand. */
3251 else
3270 {
3273 /* A COND_EXPR may have a throw as one operand, which
3274 then has void type. Just leave void operands
3275 as they are. */
3281 }
3314 }
3317 }
3319 /* Return a simplified tree node for the truth-negation of ARG. This
3320 never alters ARG itself. We assume that ARG is an operation that
3321 returns a truth value (0 or 1).
3323 FIXME: one would think we would fold the result, but it causes
3324 problems with the dominator optimizer. */
3326 tree
3328 {
3329 tree tem;
3339 }
3341 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3342 operands are another bit-wise operation with a common input. If so,
3343 distribute the bit operations to save an operation and possibly two if
3344 constants are involved. For example, convert
3345 (A | B) & (A | C) into A | (B & C)
3346 Further simplification will occur if B and C are constants.
3348 If this optimization cannot be done, 0 will be returned. */
3350 static tree
3352 {
3353 tree common;
3363 {
3367 }
3369 {
3373 }
3375 {
3379 }
3381 {
3385 }
3386 else
3391 }
3393 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3394 with code CODE. This optimization is unsafe. */
3395 static tree
3397 {
3401 /* (A / C) +- (B / C) -> (A +- B) / C. */
3411 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3416 {
3428 }
3431 }
3432 \f
3433 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3434 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3436 static tree
3439 {
3440 tree result;
3443 {
3450 }
3458 }
3460 /* Optimize a bit-field compare.
3462 There are two cases: First is a compare against a constant and the
3463 second is a comparison of two items where the fields are at the same
3464 bit position relative to the start of a chunk (byte, halfword, word)
3465 large enough to contain it. In these cases we can avoid the shift
3466 implicit in bitfield extractions.
3468 For constants, we emit a compare of the shifted constant with the
3469 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3470 compared. For two fields at the same position, we do the ANDs with the
3471 similar mask and compare the result of the ANDs.
3473 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3474 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3475 are the left and right operands of the comparison, respectively.
3477 If the optimization described above can be done, we return the resulting
3478 tree. Otherwise we return zero. */
3480 static tree
3483 {
3492 tree mask;
3493 tree offset;
3495 /* Get all the information about the extractions being done. If the bit size
3496 if the same as the size of the underlying object, we aren't doing an
3497 extraction at all and so can do nothing. We also don't want to
3498 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3499 then will no longer be able to replace it. */
3507 {
3508 /* If this is not a constant, we can only do something if bit positions,
3509 sizes, and signedness are the same. */
3517 }
3519 /* See if we can find a mode to refer to this field. We should be able to,
3520 but fail if we can't. */
3529 /* Set signed and unsigned types of the precision of this mode for the
3530 shifts below. */
3534 /* Compute the bit position and size for the new reference and our offset
3535 within it. If the new reference is the same size as the original, we
3536 won't optimize anything, so return zero. */
3546 /* Make the mask to be used against the extracted field. */
3555 /* If not comparing with constant, just rework the comparison
3556 and return. */
3561 mask),
3565 mask));
3567 /* Otherwise, we are handling the constant case. See if the constant is too
3568 big for the field. Warn and return a tree of for 0 (false) if so. We do
3569 this not only for its own sake, but to avoid having to test for this
3570 error case below. If we didn't, we might generate wrong code.
3572 For unsigned fields, the constant shifted right by the field length should
3573 be all zero. For signed fields, the high-order bits should agree with
3574 the sign bit. */
3577 {
3581 {
3585 }
3586 }
3587 else
3588 {
3592 {
3596 }
3597 }
3599 /* Single-bit compares should always be against zero. */
3601 {
3604 }
3606 /* Make a new bitfield reference, shift the constant over the
3607 appropriate number of bits and mask it with the computed mask
3608 (in case this was a signed field). If we changed it, make a new one. */
3611 {
3614 }
3624 rhs);
3625 }
3626 \f
3627 /* Subroutine for fold_truthop: decode a field reference.
3629 If EXP is a comparison reference, we return the innermost reference.
3631 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3632 set to the starting bit number.
3634 If the innermost field can be completely contained in a mode-sized
3635 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3637 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3638 otherwise it is not changed.
3640 *PUNSIGNEDP is set to the signedness of the field.
3642 *PMASK is set to the mask used. This is either contained in a
3643 BIT_AND_EXPR or derived from the width of the field.
3645 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3647 Return 0 if this is not a component reference or is one that we can't
3648 do anything with. */
3650 static tree
3655 {
3659 tree unsigned_type;
3662 /* All the optimizations using this function assume integer fields.
3663 There are problems with FP fields since the type_for_size call
3664 below can fail for, e.g., XFmode. */
3668 /* We are interested in the bare arrangement of bits, so strip everything
3669 that doesn't affect the machine mode. However, record the type of the
3670 outermost expression if it may matter below. */
3678 {
3684 }
3693 /* If the number of bits in the reference is the same as the bitsize of
3694 the outer type, then the outer type gives the signedness. Otherwise
3695 (in case of a small bitfield) the signedness is unchanged. */
3699 /* Compute the mask to access the bitfield. */
3709 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3717 }
3719 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3720 bit positions. */
3722 static int
3724 {
3727 tree tmask;
3732 return
3739 }
3741 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3742 represents the sign bit of EXP's type. If EXP represents a sign
3743 or zero extension, also test VAL against the unextended type.
3744 The return value is the (sub)expression whose sign bit is VAL,
3745 or NULL_TREE otherwise. */
3747 static tree
3749 {
3753 tree t;
3755 /* Tree EXP must have an integral type. */
3760 /* Tree VAL must be an integer constant. */
3767 {
3774 }
3775 else
3776 {
3783 }
3785 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3786 treat VAL as if it were unsigned. */
3791 /* Handle extension from a narrower type. */
3797 }
3799 /* Subroutine for fold_truthop: determine if an operand is simple enough
3800 to be evaluated unconditionally. */
3802 static int
3804 {
3805 /* Strip any conversions that don't change the machine mode. */
3814 /* Don't regard global variables as simple. They may be
3815 allocated in ways unknown to the compiler (shared memory,
3816 #pragma weak, etc). */
3819 /* Loading a static variable is unduly expensive, but global
3820 registers aren't expensive. */
3822 }
3823 \f
3824 /* The following functions are subroutines to fold_range_test and allow it to
3825 try to change a logical combination of comparisons into a range test.
3827 For example, both
3828 X == 2 || X == 3 || X == 4 || X == 5
3829 and
3830 X >= 2 && X <= 5
3831 are converted to
3832 (unsigned) (X - 2) <= 3
3834 We describe each set of comparisons as being either inside or outside
3835 a range, using a variable named like IN_P, and then describe the
3836 range with a lower and upper bound. If one of the bounds is omitted,
3837 it represents either the highest or lowest value of the type.
3839 In the comments below, we represent a range by two numbers in brackets
3840 preceded by a "+" to designate being inside that range, or a "-" to
3841 designate being outside that range, so the condition can be inverted by
3842 flipping the prefix. An omitted bound is represented by a "-". For
3843 example, "- [-, 10]" means being outside the range starting at the lowest
3844 possible value and ending at 10, in other words, being greater than 10.
3845 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3846 always false.
3848 We set up things so that the missing bounds are handled in a consistent
3849 manner so neither a missing bound nor "true" and "false" need to be
3850 handled using a special case. */
3852 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3853 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3854 and UPPER1_P are nonzero if the respective argument is an upper bound
3855 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3856 must be specified for a comparison. ARG1 will be converted to ARG0's
3857 type if both are specified. */
3859 static tree
3862 {
3863 tree tem;
3867 /* If neither arg represents infinity, do the normal operation.
3868 Else, if not a comparison, return infinity. Else handle the special
3869 comparison rules. Note that most of the cases below won't occur, but
3870 are handled for consistency. */
3873 {
3878 }
3883 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3884 for neither. In real maths, we cannot assume open ended ranges are
3885 the same. But, this is computer arithmetic, where numbers are finite.
3886 We can therefore make the transformation of any unbounded range with
3887 the value Z, Z being greater than any representable number. This permits
3888 us to treat unbounded ranges as equal. */
3892 {
3913 }
3916 }
3917 \f
3918 /* Given EXP, a logical expression, set the range it is testing into
3919 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
3920 actually being tested. *PLOW and *PHIGH will be made of the same
3921 type as the returned expression. If EXP is not a comparison, we
3922 will most likely not be returning a useful value and range. Set
3923 *STRICT_OVERFLOW_P to true if the return value is only valid
3924 because signed overflow is undefined; otherwise, do not change
3925 *STRICT_OVERFLOW_P. */
3927 static tree
3930 {
3937 /* Start with simply saying "EXP != 0" and then look at the code of EXP
3938 and see if we can refine the range. Some of the cases below may not
3939 happen, but it doesn't seem worth worrying about this. We "continue"
3940 the outer loop when we've changed something; otherwise we "break"
3941 the switch, which will "break" the while. */
3947 {
3952 {
3964 }
3967 {
3974 /* We can only do something if the range is testing for zero
3975 and if the second operand is an integer constant. Note that
3976 saying something is "in" the range we make is done by
3977 complementing IN_P since it will set in the initial case of
3978 being not equal to zero; "out" is leaving it alone. */
3985 {
4006 }
4008 /* If this is an unsigned comparison, we also know that EXP is
4009 greater than or equal to zero. We base the range tests we make
4010 on that fact, so we record it here so we can parse existing
4011 range tests. We test arg0_type since often the return type
4012 of, e.g. EQ_EXPR, is boolean. */
4014 {
4018 NULL_TREE))
4023 /* If the high bound is missing, but we have a nonzero low
4024 bound, reverse the range so it goes from zero to the low bound
4025 minus 1. */
4027 {
4032 }
4033 }
4039 /* (-x) IN [a,b] -> x in [-b, -a] */
4051 /* ~ X -> -X - 1 */
4060 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4061 move a constant to the other side. */
4066 /* If EXP is signed, any overflow in the computation is undefined,
4067 so we don't worry about it so long as our computations on
4068 the bounds don't overflow. For unsigned, overflow is defined
4069 and this is exactly the right thing. */
4081 /* Check for an unsigned range which has wrapped around the maximum
4082 value thus making n_high < n_low, and normalize it. */
4084 {
4090 /* If the range is of the form +/- [ x+1, x ], we won't
4091 be able to normalize it. But then, it represents the
4092 whole range or the empty set, so make it
4093 +/- [ -, - ]. */
4097 else
4099 }
4100 else
4124 /* If we're converting arg0 from an unsigned type, to exp,
4125 a signed type, we will be doing the comparison as unsigned.
4126 The tests above have already verified that LOW and HIGH
4127 are both positive.
4129 So we have to ensure that we will handle large unsigned
4130 values the same way that the current signed bounds treat
4131 negative values. */
4134 {
4135 tree high_positive;
4139 /* A range without an upper bound is, naturally, unbounded.
4140 Since convert would have cropped a very large value, use
4141 the max value for the destination type. */
4142 high_positive
4149 high_positive),
4151 integer_one_node));
4153 /* If the low bound is specified, "and" the range with the
4154 range for which the original unsigned value will be
4155 positive. */
4157 {
4161 integer_zero_node),
4162 high_positive))
4166 }
4167 else
4168 {
4169 /* Otherwise, "or" the range with the range of the input
4170 that will be interpreted as negative. */
4174 integer_zero_node),
4175 high_positive))
4179 }
4180 }
4188 }
4191 }
4193 /* If EXP is a constant, we can evaluate whether this is true or false. */
4195 {
4202 }
4206 }
4207 \f
4208 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4209 type, TYPE, return an expression to test if EXP is in (or out of, depending
4210 on IN_P) the range. Return 0 if the test couldn't be created. */
4212 static tree
4214 {
4216 tree value;
4218 #ifdef HAVE_canonicalize_funcptr_for_compare
4219 /* Disable this optimization for function pointer expressions
4220 on targets that require function pointer canonicalization. */
4225 #endif
4228 {
4234 }
4252 {
4254 {
4258 }
4260 }
4262 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4264 {
4266 HOST_WIDE_INT hi;
4271 {
4274 }
4275 else
4276 {
4279 }
4282 {
4284 {
4287 }
4290 }
4291 }
4293 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4294 This requires wrap-around arithmetics for the type of the expression. */
4296 {
4298 /* There is no requirement that LOW be within the range of ETYPE
4299 if the latter is a subtype. It must, however, be within the base
4300 type of ETYPE. So be sure we do the subtraction in that type. */
4313 }
4315 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4318 {
4321 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4322 for the type in question, as we rely on this here. */
4332 else
4334 }
4348 }
4349 \f
4350 /* Return the predecessor of VAL in its type, handling the infinite case. */
4352 static tree
4354 {
4360 else
4362 }
4364 /* Return the successor of VAL in its type, handling the infinite case. */
4366 static tree
4368 {
4374 else
4376 }
4378 /* Given two ranges, see if we can merge them into one. Return 1 if we
4379 can, 0 if we can't. Set the output range into the specified parameters. */
4381 static int
4384 {
4388 tree tem;
4398 /* Make range 0 be the range that starts first, or ends last if they
4399 start at the same value. Swap them if it isn't. */
4402 || (lowequal
4405 {
4409 }
4411 /* Now flag two cases, whether the ranges are disjoint or whether the
4412 second range is totally subsumed in the first. Note that the tests
4413 below are simplified by the ones above. */
4419 /* We now have four cases, depending on whether we are including or
4420 excluding the two ranges. */
4422 {
4423 /* If they don't overlap, the result is false. If the second range
4424 is a subset it is the result. Otherwise, the range is from the start
4425 of the second to the end of the first. */
4430 else
4432 }
4435 {
4436 /* If they don't overlap, the result is the first range. If they are
4437 equal, the result is false. If the second range is a subset of the
4438 first, and the ranges begin at the same place, we go from just after
4439 the end of the second range to the end of the first. If the second
4440 range is not a subset of the first, or if it is a subset and both
4441 ranges end at the same place, the range starts at the start of the
4442 first range and ends just before the second range.
4443 Otherwise, we can't describe this as a single range. */
4449 {
4454 {
4455 /* We are in the weird situation where high0 > high1 but
4456 high1 has no successor. Punt. */
4458 }
4459 }
4461 {
4466 {
4467 /* low0 < low1 but low1 has no predecessor. Punt. */
4469 }
4470 }
4471 else
4473 }
4476 {
4477 /* If they don't overlap, the result is the second range. If the second
4478 is a subset of the first, the result is false. Otherwise,
4479 the range starts just after the first range and ends at the
4480 end of the second. */
4485 else
4486 {
4491 {
4492 /* high1 > high0 but high0 has no successor. Punt. */
4494 }
4495 }
4496 }
4498 else
4499 {
4500 /* The case where we are excluding both ranges. Here the complex case
4501 is if they don't overlap. In that case, the only time we have a
4502 range is if they are adjacent. If the second is a subset of the
4503 first, the result is the first. Otherwise, the range to exclude
4504 starts at the beginning of the first range and ends at the end of the
4505 second. */
4507 {
4512 else
4513 {
4514 /* Canonicalize - [min, x] into - [-, x]. */
4517 {
4522 /* FALLTHROUGH */
4535 }
4537 /* Canonicalize - [x, max] into - [x, -]. */
4540 {
4545 /* FALLTHROUGH */
4560 }
4562 /* The ranges might be also adjacent between the maximum and
4563 minimum values of the given type. For
4564 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4565 return + [x + 1, y - 1]. */
4567 {
4574 }
4575 else
4577 }
4578 }
4581 else
4583 }
4587 }
4588 \f
4590 /* Subroutine of fold, looking inside expressions of the form
4591 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4592 of the COND_EXPR. This function is being used also to optimize
4593 A op B ? C : A, by reversing the comparison first.
4595 Return a folded expression whose code is not a COND_EXPR
4596 anymore, or NULL_TREE if no folding opportunity is found. */
4598 static tree
4600 {
4605 tree tem;
4610 /* If we have A op 0 ? A : -A, consider applying the following
4611 transformations:
4613 A == 0? A : -A same as -A
4614 A != 0? A : -A same as A
4615 A >= 0? A : -A same as abs (A)
4616 A > 0? A : -A same as abs (A)
4617 A <= 0? A : -A same as -abs (A)
4618 A < 0? A : -A same as -abs (A)
4620 None of these transformations work for modes with signed
4621 zeros. If A is +/-0, the first two transformations will
4622 change the sign of the result (from +0 to -0, or vice
4623 versa). The last four will fix the sign of the result,
4624 even though the original expressions could be positive or
4625 negative, depending on the sign of A.
4627 Note that all these transformations are correct if A is
4628 NaN, since the two alternatives (A and -A) are also NaNs. */
4634 /* In the case that A is of the form X-Y, '-A' (arg2) may
4635 have already been folded to Y-X, check for that. */
4643 {
4655 /* Fall through. */
4677 }
4679 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4680 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4681 both transformations are correct when A is NaN: A != 0
4682 is then true, and A == 0 is false. */
4685 {
4690 }
4692 /* Try some transformations of A op B ? A : B.
4694 A == B? A : B same as B
4695 A != B? A : B same as A
4696 A >= B? A : B same as max (A, B)
4697 A > B? A : B same as max (B, A)
4698 A <= B? A : B same as min (A, B)
4699 A < B? A : B same as min (B, A)
4701 As above, these transformations don't work in the presence
4702 of signed zeros. For example, if A and B are zeros of
4703 opposite sign, the first two transformations will change
4704 the sign of the result. In the last four, the original
4705 expressions give different results for (A=+0, B=-0) and
4706 (A=-0, B=+0), but the transformed expressions do not.
4708 The first two transformations are correct if either A or B
4709 is a NaN. In the first transformation, the condition will
4710 be false, and B will indeed be chosen. In the case of the
4711 second transformation, the condition A != B will be true,
4712 and A will be chosen.
4714 The conversions to max() and min() are not correct if B is
4715 a number and A is not. The conditions in the original
4716 expressions will be false, so all four give B. The min()
4717 and max() versions would give a NaN instead. */
4719 /* Avoid these transformations if the COND_EXPR may be used
4720 as an lvalue in the C++ front-end. PR c++/19199. */
4721 && (in_gimple_form
4726 {
4731 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4733 {
4737 }
4740 {
4749 /* In C++ a ?: expression can be an lvalue, so put the
4750 operand which will be used if they are equal first
4751 so that we can convert this back to the
4752 corresponding COND_EXPR. */
4754 {
4761 }
4768 {
4775 }
4788 }
4789 }
4791 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4792 we might still be able to simplify this. For example,
4793 if C1 is one less or one more than C2, this might have started
4794 out as a MIN or MAX and been transformed by this function.
4795 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4801 {
4803 /* We can replace A with C1 in this case. */
4808 /* If C1 is C2 + 1, this is min(A, C2). */
4810 OEP_ONLY_CONST)
4814 OEP_ONLY_CONST))
4820 /* If C1 is C2 - 1, this is min(A, C2). */
4822 OEP_ONLY_CONST)
4826 OEP_ONLY_CONST))
4832 /* If C1 is C2 - 1, this is max(A, C2). */
4834 OEP_ONLY_CONST)
4838 OEP_ONLY_CONST))
4844 /* If C1 is C2 + 1, this is max(A, C2). */
4846 OEP_ONLY_CONST)
4850 OEP_ONLY_CONST))
4858 }
4861 }
4864 \f
4865 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4866 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4867 #endif
4869 /* EXP is some logical combination of boolean tests. See if we can
4870 merge it into some range test. Return the new tree if so. */
4872 static tree
4874 {
4882 tree tem;
4886 /* If this is an OR operation, invert both sides; we will invert
4887 again at the end. */
4891 /* If both expressions are the same, if we can merge the ranges, and we
4892 can build the range test, return it or it inverted. If one of the
4893 ranges is always true or always false, consider it to be the same
4894 expression as the other. */
4902 {
4906 }
4908 /* On machines where the branch cost is expensive, if this is a
4909 short-circuited branch and the underlying object on both sides
4910 is the same, make a non-short-circuit operation. */
4916 {
4917 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4918 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4919 which cases we can't do this. */
4927 {
4936 {
4939 WARN_STRICT_OVERFLOW_COMPARISON);
4943 }
4944 }
4945 }
4948 }
4949 \f
4950 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
4951 bit value. Arrange things so the extra bits will be set to zero if and
4952 only if C is signed-extended to its full width. If MASK is nonzero,
4953 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4955 static tree
4957 {
4960 tree temp;
4965 /* We work by getting just the sign bit into the low-order bit, then
4966 into the high-order bit, then sign-extend. We then XOR that value
4967 with C. */
4971 /* We must use a signed type in order to get an arithmetic right shift.
4972 However, we must also avoid introducing accidental overflows, so that
4973 a subsequent call to integer_zerop will work. Hence we must
4974 do the type conversion here. At this point, the constant is either
4975 zero or one, and the conversion to a signed type can never overflow.
4976 We could get an overflow if this conversion is done anywhere else. */
4985 /* If necessary, convert the type back to match the type of C. */
4990 }
4991 \f
4992 /* Find ways of folding logical expressions of LHS and RHS:
4993 Try to merge two comparisons to the same innermost item.
4994 Look for range tests like "ch >= '0' && ch <= '9'".
4995 Look for combinations of simple terms on machines with expensive branches
4996 and evaluate the RHS unconditionally.
4998 For example, if we have p->a == 2 && p->b == 4 and we can make an
4999 object large enough to span both A and B, we can do this with a comparison
5000 against the object ANDed with the a mask.
5002 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5003 operations to do this with one comparison.
5005 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5006 function and the one above.
5008 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5009 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5011 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5012 two operands.
5014 We return the simplified tree or 0 if no optimization is possible. */
5016 static tree
5018 {
5019 /* If this is the "or" of two comparisons, we can do something if
5020 the comparisons are NE_EXPR. If this is the "and", we can do something
5021 if the comparisons are EQ_EXPR. I.e.,
5022 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5024 WANTED_CODE is this operation code. For single bit fields, we can
5025 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5026 comparison for one-bit fields. */
5048 /* Start by getting the comparison codes. Fail if anything is volatile.
5049 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5050 it were surrounded with a NE_EXPR. */
5059 {
5063 }
5066 {
5070 }
5081 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5084 {
5085 tree result;
5088 {
5093 }
5096 {
5102 }
5103 }
5108 /* If the RHS can be evaluated unconditionally and its operands are
5109 simple, it wins to evaluate the RHS unconditionally on machines
5110 with expensive branches. In this case, this isn't a comparison
5111 that can be merged. Avoid doing this if the RHS is a floating-point
5112 comparison since those can trap. */
5118 {
5119 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5129 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5140 {
5144 }
5145 }
5147 /* See if the comparisons can be merged. Then get all the parameters for
5148 each side. */
5172 /* It must be true that the inner operation on the lhs of each
5173 comparison must be the same if we are to be able to do anything.
5174 Then see if we have constants. If not, the same must be true for
5175 the rhs's. */
5186 else
5189 /* If either comparison code is not correct for our logical operation,
5190 fail. However, we can convert a one-bit comparison against zero into
5191 the opposite comparison against that bit being set in the field. */
5195 {
5197 {
5198 /* Make the left operand unsigned, since we are only interested
5199 in the value of one bit. Otherwise we are doing the wrong
5200 thing below. */
5203 }
5204 else
5206 }
5208 /* This is analogous to the code for l_const above. */
5210 {
5212 {
5215 }
5216 else
5218 }
5220 /* After this point all optimizations will generate bit-field
5221 references, which we might not want. */
5225 /* See if we can find a mode that contains both fields being compared on
5226 the left. If we can't, fail. Otherwise, update all constants and masks
5227 to be relative to a field of that size. */
5232 volatilep);
5242 {
5245 }
5253 {
5261 {
5265 }
5266 }
5268 {
5276 {
5280 }
5281 }
5283 /* If the right sides are not constant, do the same for it. Also,
5284 disallow this optimization if a size or signedness mismatch occurs
5285 between the left and right sides. */
5287 {
5290 /* Make sure the two fields on the right
5291 correspond to the left without being swapped. */
5299 volatilep);
5309 {
5312 }
5319 /* Make a mask that corresponds to both fields being compared.
5320 Do this for both items being compared. If the operands are the
5321 same size and the bits being compared are in the same position
5322 then we can do this by masking both and comparing the masked
5323 results. */
5327 {
5339 }
5341 /* There is still another way we can do something: If both pairs of
5342 fields being compared are adjacent, we may be able to make a wider
5343 field containing them both.
5345 Note that we still must mask the lhs/rhs expressions. Furthermore,
5346 the mask must be shifted to account for the shift done by
5347 make_bit_field_ref. */
5352 {
5353 tree type;
5365 /* Convert to the smaller type before masking out unwanted bits. */
5368 {
5370 {
5374 }
5376 {
5380 }
5381 }
5390 }
5393 }
5395 /* Handle the case of comparisons with constants. If there is something in
5396 common between the masks, those bits of the constants must be the same.
5397 If not, the condition is always false. Test for this to avoid generating
5398 incorrect code below. */
5403 {
5405 {
5408 }
5409 else
5410 {
5413 }
5414 }
5416 /* Construct the expression we will return. First get the component
5417 reference we will make. Unless the mask is all ones the width of
5418 that field, perform the mask operation. Then compare with the
5419 merged constant. */
5429 }
5430 \f
5431 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5432 constant. */
5434 static tree
5436 {
5440 tree minmax_const;
5442 tree inner;
5452 /* If something does not permit us to optimize, return the original tree. */
5460 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5461 and GT_EXPR, doing the rest with recursive calls using logical
5462 simplifications. */
5464 {
5466 {
5472 }
5475 return
5477 optimize_minmax_comparison
5479 optimize_minmax_comparison
5484 /* MAX (X, 0) == 0 -> X <= 0 */
5488 /* MAX (X, 0) == 5 -> X == 5 */
5492 /* MAX (X, 0) == -1 -> false */
5496 /* MIN (X, 0) == 0 -> X >= 0 */
5500 /* MIN (X, 0) == 5 -> false */
5503 else
5504 /* MIN (X, 0) == -1 -> X == -1 */
5509 /* MAX (X, 0) > 0 -> X > 0
5510 MAX (X, 0) > 5 -> X > 5 */
5514 /* MAX (X, 0) > -1 -> true */
5518 /* MIN (X, 0) > 0 -> false
5519 MIN (X, 0) > 5 -> false */
5522 else
5523 /* MIN (X, 0) > -1 -> X > -1 */
5528 }
5529 }
5530 \f
5531 /* T is an integer expression that is being multiplied, divided, or taken a
5532 modulus (CODE says which and what kind of divide or modulus) by a
5533 constant C. See if we can eliminate that operation by folding it with
5534 other operations already in T. WIDE_TYPE, if non-null, is a type that
5535 should be used for the computation if wider than our type.
5537 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5538 (X * 2) + (Y * 4). We must, however, be assured that either the original
5539 expression would not overflow or that overflow is undefined for the type
5540 in the language in question.
5542 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5543 the machine has a multiply-accumulate insn or that this is part of an
5544 addressing calculation.
5546 If we return a non-null expression, it is an equivalent form of the
5547 original computation, but need not be in the original type.
5549 We set *STRICT_OVERFLOW_P to true if the return values depends on
5550 signed overflow being undefined. Otherwise we do not change
5551 *STRICT_OVERFLOW_P. */
5553 static tree
5556 {
5557 /* To avoid exponential search depth, refuse to allow recursion past
5558 three levels. Beyond that (1) it's highly unlikely that we'll find
5559 something interesting and (2) we've probably processed it before
5560 when we built the inner expression. */
5563 tree ret;
5568 depth++;
5570 depth--;
5573 }
5575 static tree
5578 {
5589 /* Don't deal with constants of zero here; they confuse the code below. */
5599 /* Note that we need not handle conditional operations here since fold
5600 already handles those cases. So just do arithmetic here. */
5602 {
5604 /* For a constant, we can always simplify if we are a multiply
5605 or (for divide and modulus) if it is a multiple of our constant. */
5613 /* If op0 is an expression ... */
5618 /* ... and is unsigned, and its type is smaller than ctype,
5619 then we cannot pass through as widening. */
5625 /* ... or this is a truncation (t is narrower than op0),
5626 then we cannot pass through this narrowing. */
5629 /* ... or signedness changes for division or modulus,
5630 then we cannot pass through this conversion. */
5636 /* Pass the constant down and see if we can make a simplification. If
5637 we can, replace this expression with the inner simplification for
5638 possible later conversion to our or some other type. */
5643 code == MULT_EXPR
5645 strict_overflow_p))))
5650 /* If widening the type changes it from signed to unsigned, then we
5651 must avoid building ABS_EXPR itself as unsigned. */
5653 {
5657 {
5660 }
5662 }
5663 /* If the constant is negative, we cannot simplify this. */
5666 /* FALLTHROUGH */
5674 /* If widening the type changes the signedness, then we can't perform
5675 this optimization as that changes the result. */
5679 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5685 {
5692 }
5696 /* If the second operand is constant, this is a multiplication
5697 or floor division, by a power of two, so we can treat it that
5698 way unless the multiplier or divisor overflows. Signed
5699 left-shift overflow is implementation-defined rather than
5700 undefined in C90, so do not convert signed left shift into
5701 multiplication. */
5704 /* const_binop may not detect overflow correctly,
5705 so check for it explicitly here. */
5710 size_one_node,
5720 /* See if we can eliminate the operation on both sides. If we can, we
5721 can return a new PLUS or MINUS. If we can't, the only remaining
5722 cases where we can do anything are if the second operand is a
5723 constant. */
5729 /* If not multiplication, we can only do this if both operands
5730 are divisible by c. */
5733 {
5738 }
5740 /* If this was a subtraction, negate OP1 and set it to be an addition.
5741 This simplifies the logic below. */
5748 /* If either OP1 or C are negative, this optimization is not safe for
5749 some of the division and remainder types while for others we need
5750 to change the code. */
5752 {
5760 }
5762 /* If it's a multiply or a division/modulus operation of a multiple
5763 of our constant, do the operation and verify it doesn't overflow. */
5766 {
5769 /* We allow the constant to overflow with wrapping semantics. */
5773 }
5774 else
5777 /* If we have an unsigned type is not a sizetype, we cannot widen
5778 the operation since it will change the result if the original
5779 computation overflowed. */
5785 /* If we were able to eliminate our operation from the first side,
5786 apply our operation to the second side and reform the PLUS. */
5790 /* The last case is if we are a multiply. In that case, we can
5791 apply the distributive law to commute the multiply and addition
5792 if the multiplication of the constants doesn't overflow. */
5798 op1);
5803 /* We have a special case here if we are doing something like
5804 (C * 8) % 4 since we know that's zero. */
5811 /* ... fall through ... */
5815 /* If we can extract our operation from the LHS, do so and return a
5816 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5817 do something only if the second operand is a constant. */
5831 /* If these are the same operation types, we can associate them
5832 assuming no overflow. */
5839 /* If these operations "cancel" each other, we have the main
5840 optimizations of this pass, which occur when either constant is a
5841 multiple of the other, in which case we replace this with either an
5842 operation or CODE or TCODE.
5844 If we have an unsigned type that is not a sizetype, we cannot do
5845 this since it will change the result if the original computation
5846 overflowed. */
5853 {
5855 {
5862 }
5864 {
5871 }
5872 }
5877 }
5880 }
5881 \f
5882 /* Return a node which has the indicated constant VALUE (either 0 or
5883 1), and is of the indicated TYPE. */
5885 tree
5887 {
5892 else
5894 }
5897 /* Return true if expr looks like an ARRAY_REF and set base and
5898 offset to the appropriate trees. If there is no offset,
5899 offset is set to NULL_TREE. Base will be canonicalized to
5900 something you can get the element type from using
5901 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5902 in bytes to the base. */
5904 static bool
5906 {
5907 /* One canonical form is a PLUS_EXPR with the first
5908 argument being an ADDR_EXPR with a possible NOP_EXPR
5909 attached. */
5911 {
5914 /* Strip NOP_EXPRs here because the C frontends and/or
5915 folders present us (int *)&x.a + 4B possibly. */
5918 {
5922 else
5926 }
5927 }
5928 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5929 which we transform into an ADDR_EXPR with appropriate
5930 offset. For other arguments to the ADDR_EXPR we assume
5931 zero offset and as such do not care about the ADDR_EXPR
5932 type and strip possible nops from it. */
5934 {
5937 {
5942 }
5943 else
5944 {
5945 /* Handle array-to-pointer decay as &a. */
5948 else
5951 }
5953 }
5954 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
5957 {
5961 }
5964 }
5967 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
5968 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
5969 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
5970 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
5971 COND is the first argument to CODE; otherwise (as in the example
5972 given here), it is the second argument. TYPE is the type of the
5973 original expression. Return NULL_TREE if no simplification is
5974 possible. */
5976 static tree
5980 {
5987 /* This transformation is only worthwhile if we don't have to wrap
5988 arg in a SAVE_EXPR, and the operation can be simplified on at least
5989 one of the branches once its pushed inside the COND_EXPR. */
5994 {
5998 /* If this operand throws an expression, then it does not make
5999 sense to try to perform a logical or arithmetic operation
6000 involving it. */
6005 }
6006 else
6007 {
6012 }
6016 {
6020 else
6022 }
6024 {
6028 else
6030 }
6034 }
6036 \f
6037 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6039 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6040 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6041 ADDEND is the same as X.
6043 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6044 and finite. The problematic cases are when X is zero, and its mode
6045 has signed zeros. In the case of rounding towards -infinity,
6046 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6047 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6049 static bool
6051 {
6055 /* Don't allow the fold with -fsignaling-nans. */
6059 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6063 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6068 /* The mode has signed zeros, and we have to honor their sign.
6069 In this situation, there is only one case we can return true for.
6070 X - 0 is the same as X unless rounding towards -infinity is
6071 supported. */
6073 }
6075 /* Subroutine of fold() that checks comparisons of built-in math
6076 functions against real constants.
6078 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6079 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6080 is the type of the result and ARG0 and ARG1 are the operands of the
6081 comparison. ARG1 must be a TREE_REAL_CST.
6083 The function returns the constant folded tree if a simplification
6084 can be made, and NULL_TREE otherwise. */
6086 static tree
6089 {
6090 REAL_VALUE_TYPE c;
6093 {
6099 {
6100 /* sqrt(x) < y is always false, if y is negative. */
6104 /* sqrt(x) > y is always true, if y is negative and we
6105 don't care about NaNs, i.e. negative values of x. */
6109 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6112 }
6114 {
6115 REAL_VALUE_TYPE c2;
6121 {
6122 /* sqrt(x) > y is x == +Inf, when y is very large. */
6127 /* sqrt(x) > y is always false, when y is very large
6128 and we don't care about infinities. */
6130 }
6132 /* sqrt(x) > c is the same as x > c*c. */
6135 }
6137 {
6138 REAL_VALUE_TYPE c2;
6144 {
6145 /* sqrt(x) < y is always true, when y is a very large
6146 value and we don't care about NaNs or Infinities. */
6150 /* sqrt(x) < y is x != +Inf when y is very large and we
6151 don't care about NaNs. */
6156 /* sqrt(x) < y is x >= 0 when y is very large and we
6157 don't care about Infinities. */
6162 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6171 dconst0)),
6174 c2)));
6175 }
6177 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6182 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6185 {
6190 dconst0)),
6193 c2)));
6194 }
6195 }
6196 }
6199 }
6201 /* Subroutine of fold() that optimizes comparisons against Infinities,
6202 either +Inf or -Inf.
6204 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6205 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6206 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6208 The function returns the constant folded tree if a simplification
6209 can be made, and NULL_TREE otherwise. */
6211 static tree
6213 {
6215 REAL_VALUE_TYPE max;
6216 tree temp;
6221 /* For negative infinity swap the sense of the comparison. */
6227 {
6229 /* x > +Inf is always false, if with ignore sNANs. */
6235 /* x <= +Inf is always true, if we don't case about NaNs. */
6239 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6242 {
6245 }
6250 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6256 /* x < +Inf is always equal to x <= DBL_MAX. */
6262 /* x != +Inf is always equal to !(x > DBL_MAX). */
6268 /* The transformation below creates non-gimple code and thus is
6269 not appropriate if we are in gimple form. */
6279 }
6282 }
6284 /* Subroutine of fold() that optimizes comparisons of a division by
6285 a nonzero integer constant against an integer constant, i.e.
6286 X/C1 op C2.
6288 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6289 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6290 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6292 The function returns the constant folded tree if a simplification
6293 can be made, and NULL_TREE otherwise. */
6295 static tree
6297 {
6302 HOST_WIDE_INT hpart;
6307 /* We have to do this the hard way to detect unsigned overflow.
6308 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6319 {
6323 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6332 }
6334 {
6337 {
6356 }
6357 }
6358 else
6359 {
6360 /* A negative divisor reverses the relational operators. */
6365 {
6384 }
6385 }
6388 {
6409 {
6412 }
6417 {
6420 }
6425 {
6428 }
6433 {
6436 }
6441 }
6444 }
6447 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6448 equality/inequality test, then return a simplified form of the test
6449 using a sign testing. Otherwise return NULL. TYPE is the desired
6450 result type. */
6452 static tree
6454 tree result_type)
6455 {
6456 /* If this is testing a single bit, we can optimize the test. */
6460 {
6461 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6462 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6466 /* This is only a win if casting to a signed type is cheap,
6467 i.e. when arg00's type is not a partial mode. */
6470 {
6475 }
6476 }
6479 }
6481 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6482 equality/inequality test, then return a simplified form of
6483 the test using shifts and logical operations. Otherwise return
6484 NULL. TYPE is the desired result type. */
6486 tree
6488 tree result_type)
6489 {
6490 /* If this is testing a single bit, we can optimize the test. */
6494 {
6501 tree tem;
6503 /* First, see if we can fold the single bit test into a sign-bit
6504 test. */
6506 result_type);
6510 /* Otherwise we have (A & C) != 0 where C is a single bit,
6511 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6512 Similarly for (A & C) == 0. */
6514 /* If INNER is a right shift of a constant and it plus BITNUM does
6515 not overflow, adjust BITNUM and INNER. */
6522 {
6525 }
6527 /* If we are going to be able to omit the AND below, we must do our
6528 operations as unsigned. If we must use the AND, we have a choice.
6529 Normally unsigned is faster, but for some machines signed is. */
6530 #ifdef LOAD_EXTEND_OP
6533 #else
6535 #endif
6550 /* Put the AND last so it can combine with more things. */
6554 /* Make sure to return the proper type. */
6558 }
6560 }
6562 /* Check whether we are allowed to reorder operands arg0 and arg1,
6563 such that the evaluation of arg1 occurs before arg0. */
6565 static bool
6567 {
6574 }
6576 /* Test whether it is preferable two swap two operands, ARG0 and
6577 ARG1, for example because ARG0 is an integer constant and ARG1
6578 isn't. If REORDER is true, only recommend swapping if we can
6579 evaluate the operands in reverse order. */
6581 bool
6583 {
6619 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6620 for commutative and comparison operators. Ensuring a canonical
6621 form allows the optimizers to find additional redundancies without
6622 having to explicitly check for both orderings. */
6629 }
6631 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6632 ARG0 is extended to a wider type. */
6634 static tree
6636 {
6638 tree arg1_unw;
6647 #ifdef HAVE_canonicalize_funcptr_for_compare
6648 /* Disable this optimization if we're casting a function pointer
6649 type on targets that require function pointer canonicalization. */
6654 #endif
6661 /* If possible, express the comparison in the shorter mode. */
6677 /* If we are comparing with the integer that does not fit into the range
6678 of the shorter type, the result is known. */
6689 {
6716 }
6719 }
6721 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6722 ARG0 just the signedness is changed. */
6724 static tree
6727 {
6739 #ifdef HAVE_canonicalize_funcptr_for_compare
6740 /* Disable this optimization if we're casting a function pointer
6741 type on targets that require function pointer canonicalization. */
6746 #endif
6763 {
6770 }
6771 else
6775 }
6777 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6778 step of the array. Reconstructs s and delta in the case of s * delta
6779 being an integer constant (and thus already folded).
6780 ADDR is the address. MULT is the multiplicative expression.
6781 If the function succeeds, the new address expression is returned. Otherwise
6782 NULL_TREE is returned. */
6784 static tree
6786 {
6790 tree itype;
6792 /* Canonicalize op1 into a possibly non-constant delta
6793 and an INTEGER_CST s. */
6795 {
6802 {
6805 }
6807 {
6810 }
6811 else
6813 }
6815 {
6818 }
6819 else
6820 {
6821 /* Simulate we are delta * 1. */
6824 }
6827 {
6829 {
6839 {
6842 }
6843 else
6844 {
6845 /* Try if delta is a multiple of step. */
6850 }
6853 }
6857 }
6859 /* We found the suitable array reference. So copy everything up to it,
6860 and replace the index. */
6867 {
6871 }
6879 }
6882 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6883 means A >= Y && A != MAX, but in this case we know that
6884 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6886 static tree
6888 {
6895 else
6904 {
6907 }
6909 {
6912 }
6913 else
6924 }
6926 /* Fold a sum or difference of at least one multiplication.
6927 Returns the folded tree or NULL if no simplification could be made. */
6929 static tree
6931 {
6935 /* (A * C) +- (B * C) -> (A+-B) * C.
6936 (A * C) +- A -> A * (C+-1).
6937 We are most concerned about the case where C is a constant,
6938 but other combinations show up during loop reduction. Since
6939 it is not difficult, try all four possibilities. */
6942 {
6945 }
6946 else
6947 {
6950 }
6952 {
6955 }
6956 else
6957 {
6960 }
6972 /* No identical multiplicands; see if we can find a common
6973 power-of-two factor in non-power-of-two multiplies. This
6974 can help in multi-dimensional array access. */
6977 {
6980 tree maybe_same;
6984 /* Move min of absolute values to int11. */
6987 {
6992 }
6993 else
6997 {
7005 }
7006 }
7016 }
7018 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7019 specified by EXPR into the buffer PTR of length LEN bytes.
7020 Return the number of bytes placed in the buffer, or zero
7021 upon failure. */
7023 static int
7025 {
7036 {
7040 else
7045 {
7052 else
7054 }
7055 else
7058 }
7060 }
7063 /* Subroutine of native_encode_expr. Encode the REAL_CST
7064 specified by EXPR into the buffer PTR of length LEN bytes.
7065 Return the number of bytes placed in the buffer, or zero
7066 upon failure. */
7068 static int
7070 {
7076 /* There are always 32 bits in each long, no matter the size of
7077 the hosts long. We handle floating point representations with
7078 up to 192 bits. */
7089 {
7094 {
7101 else
7103 }
7104 else
7107 }
7109 }
7111 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7112 specified by EXPR into the buffer PTR of length LEN bytes.
7113 Return the number of bytes placed in the buffer, or zero
7114 upon failure. */
7116 static int
7118 {
7120 tree part;
7131 }
7134 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7135 specified by EXPR into the buffer PTR of length LEN bytes.
7136 Return the number of bytes placed in the buffer, or zero
7137 upon failure. */
7139 static int
7141 {
7151 {
7153 {
7156 }
7157 else
7161 {
7164 }
7165 else
7166 {
7170 }
7172 }
7174 }
7177 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7178 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7179 buffer PTR of length LEN bytes. Return the number of bytes
7180 placed in the buffer, or zero upon failure. */
7182 static int
7184 {
7186 {
7201 }
7202 }
7205 /* Subroutine of native_interpret_expr. Interpret the contents of
7206 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7207 If the buffer cannot be interpreted, return NULL_TREE. */
7209 static tree
7211 {
7225 {
7228 {
7235 else
7237 }
7238 else
7244 else
7247 }
7251 }
7254 /* Subroutine of native_interpret_expr. Interpret the contents of
7255 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7256 If the buffer cannot be interpreted, return NULL_TREE. */
7258 static tree
7260 {
7265 /* There are always 32 bits in each long, no matter the size of
7266 the hosts long. We handle floating point representations with
7267 up to 192 bits. */
7268 REAL_VALUE_TYPE r;
7279 {
7282 {
7289 else
7291 }
7292 else
7297 }
7301 }
7304 /* Subroutine of native_interpret_expr. Interpret the contents of
7305 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7306 If the buffer cannot be interpreted, return NULL_TREE. */
7308 static tree
7310 {
7325 }
7328 /* Subroutine of native_interpret_expr. Interpret the contents of
7329 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7330 If the buffer cannot be interpreted, return NULL_TREE. */
7332 static tree
7334 {
7346 {
7351 }
7353 }
7356 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7357 the buffer PTR of length LEN as a constant of type TYPE. For
7358 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7359 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7360 return NULL_TREE. */
7362 static tree
7364 {
7366 {
7383 }
7384 }
7387 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7388 TYPE at compile-time. If we're unable to perform the conversion
7389 return NULL_TREE. */
7391 static tree
7393 {
7394 /* We support up to 512-bit values (for V8DFmode). */
7398 /* Check that the host and target are sane. */
7407 }
7410 /* Fold a unary expression of code CODE and type TYPE with operand
7411 OP0. Return the folded expression if folding is successful.
7412 Otherwise, return NULL_TREE. */
7414 tree
7416 {
7417 tree tem;
7418 tree arg0;
7426 {
7429 {
7430 /* Don't use STRIP_NOPS, because signedness of argument type
7431 matters. */
7433 }
7434 else
7435 {
7436 /* Strip any conversions that don't change the mode. This
7437 is safe for every expression, except for a comparison
7438 expression because its signedness is derived from its
7439 operands.
7441 Note that this is done as an internal manipulation within
7442 the constant folder, in order to find the simplest
7443 representation of the arguments so that their form can be
7444 studied. In any cases, the appropriate type conversions
7445 should be put back in the tree that will get out of the
7446 constant folder. */
7448 }
7449 }
7452 {
7457 {
7467 /* If this was a conversion, and all we did was to move into
7468 inside the COND_EXPR, bring it back out. But leave it if
7469 it is a conversion from integer to integer and the
7470 result precision is no wider than a word since such a
7471 conversion is cheap and may be optimized away by combine,
7472 while it couldn't if it were outside the COND_EXPR. Then return
7473 so we don't get into an infinite recursion loop taking the
7474 conversion out and then back in. */
7486 && (INTEGRAL_TYPE_P
7498 }
7500 {
7502 {
7506 }
7510 integer_one_node),
7512 integer_zero_node));
7513 }
7514 }
7517 {
7528 /* If we have (type) (a CMP b) and type is an integral type, return
7529 new expression involving the new type. */
7534 /* Handle cases of two conversions in a row. */
7537 {
7559 /* In addition to the cases of two conversions in a row
7560 handled below, if we are converting something to its own
7561 type via an object of identical or wider precision, neither
7562 conversion is needed. */
7569 /* Likewise, if the intermediate and final types are either both
7570 float or both integer, we don't need the middle conversion if
7571 it is wider than the final type and doesn't change the signedness
7572 (for integers). Avoid this if the final type is a pointer
7573 since then we sometimes need the inner conversion. Likewise if
7574 the outer has a precision not equal to the size of its mode. */
7583 && ! final_ptr
7587 /* If we have a sign-extension of a zero-extended value, we can
7588 replace that by a single zero-extension. */
7594 /* Two conversions in a row are not needed unless:
7595 - some conversion is floating-point (overstrict for now), or
7596 - some conversion is a vector (overstrict for now), or
7597 - the intermediate type is narrower than both initial and
7598 final, or
7599 - the intermediate type and innermost type differ in signedness,
7600 and the outermost type is wider than the intermediate, or
7601 - the initial type is a pointer type and the precisions of the
7602 intermediate and final types differ, or
7603 - the final type is a pointer type and the precisions of the
7604 initial and intermediate types differ.
7605 - the final type is a pointer type and the initial type not
7606 - the initial type is a pointer to an array and the final type
7607 not. */
7608 /* Java pointer type conversions generate checks in some
7609 cases, so we explicitly disallow this optimization. */
7623 && ! (inside_ptr
7629 }
7631 /* Handle (T *)&A.B.C for A being of type T and B and C
7632 living at offset zero. This occurs frequently in
7633 C++ upcasting and then accessing the base. */
7637 {
7639 tree offset;
7645 /* If the reference was to a (constant) zero offset, we can use
7646 the address of the base if it has the same base type
7647 as the result type. */
7652 }
7656 /* Detect assigning a bitfield. */
7659 {
7660 /* Don't leave an assignment inside a conversion
7661 unless assigning a bitfield. */
7663 /* First do the assignment, then return converted constant. */
7668 }
7670 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7671 constants (if x has signed type, the sign bit cannot be set
7672 in c). This folds extension into the BIT_AND_EXPR. */
7677 {
7687 <= HOST_BITS_PER_WIDE_INT
7689 {
7696 #ifdef LOAD_EXTEND_OP
7698 && !flag_syntax_only
7701 {
7705 }
7706 #endif
7707 }
7709 {
7716 }
7717 }
7719 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
7720 T2 being pointers to types of the same size. */
7725 {
7737 }
7739 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7740 of the same precision, and X is a integer type not narrower than
7741 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7748 {
7753 }
7774 /* Convert fabs((double)float) into (double)fabsf(float). */
7777 {
7782 targ0));
7783 }
7784 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7790 /* Strip sign ops from argument. */
7792 {
7796 }
7803 {
7808 }
7810 {
7815 }
7825 /* Convert ~ (-A) to A - 1. */
7829 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7836 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7853 /* The argument to invert_truthvalue must have Boolean type. */
7857 /* Note that the operand of this must be an int
7858 and its values must be 0 or 1.
7859 ("true" is a fixed value perhaps depending on the language,
7860 but we don't handle values other than 1 correctly yet.) */
7875 {
7883 }
7885 {
7889 }
7901 {
7909 }
7911 {
7915 }
7921 }
7923 /* Fold a binary expression of code CODE and type TYPE with operands
7924 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
7925 Return the folded expression if folding is successful. Otherwise,
7926 return NULL_TREE. */
7928 static tree
7930 {
7937 else
7940 /* MIN (MAX (a, b), b) == b. */
7945 /* MIN (MAX (b, a), b) == b. */
7951 /* MIN (a, MAX (a, b)) == a. */
7957 /* MIN (a, MAX (b, a)) == a. */
7964 }
7966 /* Subroutine of fold_binary. This routine performs all of the
7967 transformations that are common to the equality/inequality
7968 operators (EQ_EXPR and NE_EXPR) and the ordering operators
7969 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
7970 fold_binary should call fold_binary. Fold a comparison with
7971 tree code CODE and type TYPE with operands OP0 and OP1. Return
7972 the folded comparison or NULL_TREE. */
7974 static tree
7976 {
7989 /* If one arg is a real or integer constant, put it last. */
7993 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8000 {
8004 tree lhs;
8013 {
8015 "when changing X +- C1 cmp C2 to "
8017 WARN_STRICT_OVERFLOW_COMPARISON);
8019 }
8020 }
8022 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8023 same object, then we can fold this to a comparison of the two offsets in
8024 signed size type. This is possible because pointer arithmetic is
8025 restricted to retain within an object and overflow on pointer differences
8026 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8028 We check flag_wrapv directly because pointers types are unsigned,
8029 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8030 normally what we want to avoid certain odd overflow cases, but
8031 not here. */
8033 && !flag_wrapv
8035 {
8041 {
8042 tree signed_size_type_node;
8045 /* By converting to signed size type we cover middle-end pointer
8046 arithmetic which operates on unsigned pointer types of size
8047 type size and ARRAY_REF offsets which are properly sign or
8048 zero extended from their type in case it is narrower than
8049 size type. */
8052 else
8056 else
8060 }
8061 }
8064 {
8072 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8077 /* (-a) CMP (-b) -> b CMP a */
8084 {
8085 REAL_VALUE_TYPE cst;
8088 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8095 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8096 /* a CMP (-0) -> a CMP 0 */
8101 /* x != NaN is always true, other ops are always false. */
8104 {
8107 }
8109 /* Fold comparisons against infinity. */
8111 {
8115 }
8116 }
8118 /* If this is a comparison of a real constant with a PLUS_EXPR
8119 or a MINUS_EXPR of a real constant, we can convert it into a
8120 comparison with a revised real constant as long as no overflow
8121 occurs when unsafe_math_optimizations are enabled. */
8133 /* Likewise, we can simplify a comparison of a real constant with
8134 a MINUS_EXPR whose first operand is also a real constant, i.e.
8135 (c1 - x) < c2 becomes x > c1-c2. */
8146 /* Fold comparisons against built-in math functions. */
8148 && flag_unsafe_math_optimizations
8150 {
8154 {
8158 }
8159 }
8160 }
8162 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
8166 /* This optimization is invalid for ordered comparisons
8167 if CONST+INCR overflows or if foo+incr might overflow.
8168 This optimization is invalid for floating point due to rounding.
8169 For pointer types we assume overflow doesn't happen. */
8173 {
8177 {
8183 }
8184 else
8185 {
8191 }
8194 /* If VAROP is a reference to a bitfield, we must mask
8195 the constant by the width of the field. */
8200 {
8205 /* First check whether the comparison would come out
8206 always the same. If we don't do that we would
8207 change the meaning with the masking. */
8220 }
8223 }
8228 {
8229 /* If we are widening one operand of an integer comparison,
8230 see if the other operand is similarly being widened. Perhaps we
8231 can do the comparison in the narrower type. */
8236 /* Or if we are changing signedness. */
8240 }
8242 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8243 constant, we can simplify it. */
8248 {
8252 }
8254 /* Simplify comparison of something with itself. (For IEEE
8255 floating-point, we can only do some of these simplifications.) */
8257 {
8259 {
8274 /* For NE, we can only do this simplification if integer
8275 or we don't honor IEEE floating point NaNs. */
8279 /* ... fall through ... */
8285 }
8286 }
8288 /* If we are comparing an expression that just has comparisons
8289 of two integer values, arithmetic expressions of those comparisons,
8290 and constants, we can simplify it. There are only three cases
8291 to check: the two values can either be equal, the first can be
8292 greater, or the second can be greater. Fold the expression for
8293 those three values. Since each value must be 0 or 1, we have
8294 eight possibilities, each of which corresponds to the constant 0
8295 or 1 or one of the six possible comparisons.
8297 This handles common cases like (a > b) == 0 but also handles
8298 expressions like ((x > y) - (y > x)) > 0, which supposedly
8299 occur in macroized code. */
8302 {
8307 /* Don't handle degenerate cases here; they should already
8308 have been handled anyway. */
8317 {
8321 /* We can't just pass T to eval_subst in case cval1 or cval2
8322 was the same as ARG1. */
8324 tree high_result
8328 arg1);
8329 tree equal_result
8333 arg1);
8334 tree low_result
8338 arg1);
8340 /* All three of these results should be 0 or 1. Confirm they are.
8341 Then use those values to select the proper code to use. */
8346 {
8347 /* Make a 3-bit mask with the high-order bit being the
8348 value for `>', the next for '=', and the low for '<'. */
8352 {
8354 /* Always false. */
8375 /* Always true. */
8377 }
8382 }
8383 }
8384 }
8386 /* Fold a comparison of the address of COMPONENT_REFs with the same
8387 type and component to a comparison of the address of the base
8388 object. In short, &x->a OP &y->a to x OP y and
8389 &x->a OP &y.a to x OP &y */
8394 {
8398 {
8404 }
8405 }
8407 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8408 into a single range test. */
8416 {
8420 }
8423 }
8426 /* Subroutine of fold_binary. Optimize complex multiplications of the
8427 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8428 argument EXPR represents the expression "z" of type TYPE. */
8430 static tree
8432 {
8437 {
8440 }
8442 {
8445 }
8446 else
8447 {
8451 }
8460 }
8463 /* Fold a binary expression of code CODE and type TYPE with operands
8464 OP0 and OP1. Return the folded expression if folding is
8465 successful. Otherwise, return NULL_TREE. */
8467 tree
8469 {
8483 /* Strip any conversions that don't change the mode. This is
8484 safe for every expression, except for a comparison expression
8485 because its signedness is derived from its operands. So, in
8486 the latter case, only strip conversions that don't change the
8487 signedness.
8489 Note that this is done as an internal manipulation within the
8490 constant folder, in order to find the simplest representation
8491 of the arguments so that their form can be studied. In any
8492 cases, the appropriate type conversions should be put back in
8493 the tree that will get out of the constant folder. */
8496 {
8499 }
8500 else
8501 {
8504 }
8506 /* Note that TREE_CONSTANT isn't enough: static var addresses are
8507 constant but we can't do arithmetic on them. */
8512 {
8517 else
8521 {
8525 }
8526 }
8528 /* If this is a commutative operation, and ARG0 is a constant, move it
8529 to ARG1 to reduce the number of tests below. */
8534 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
8536 First check for cases where an arithmetic operation is applied to a
8537 compound, conditional, or comparison operation. Push the arithmetic
8538 operation inside the compound or conditional to see if any folding
8539 can then be done. Convert comparison to conditional for this purpose.
8540 The also optimizes non-constant cases that used to be done in
8541 expand_expr.
8543 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
8544 one of the operands is a comparison and the other is a comparison, a
8545 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
8546 code below would make the expression more complex. Change it to a
8547 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
8548 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
8560 {
8564 boolean_type_node,
8572 }
8576 {
8588 {
8594 }
8597 {
8603 }
8604 }
8607 {
8609 /* A + (-B) -> A - B */
8614 /* (-A) + B -> B - A */
8620 /* Convert ~A + 1 to -A. */
8626 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
8627 same or one. */
8631 {
8635 }
8638 {
8642 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
8643 with a constant, and the two constants have no bits in common,
8644 we should treat this as a BIT_IOR_EXPR since this may produce more
8645 simplifications. */
8653 {
8656 }
8658 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
8659 (plus (plus (mult) (mult)) (foo)) so that we can
8660 take advantage of the factoring cases below. */
8667 {
8673 else
8695 parg1)));
8696 }
8698 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
8699 of the array. Loop optimizer sometimes produce this type of
8700 expressions. */
8702 {
8706 }
8708 {
8712 }
8713 }
8714 else
8715 {
8716 /* See if ARG1 is zero and X + ARG1 reduces to X. */
8720 /* Likewise if the operands are reversed. */
8724 /* Convert X + -C into X - C. */
8727 {
8733 }
8741 /* Convert x+x into x*2.0. */
8747 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
8751 {
8756 {
8757 tree tree0;
8760 }
8761 }
8762 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
8766 {
8771 {
8772 tree tree0;
8775 }
8776 }
8777 }
8779 bit_rotate:
8780 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
8781 is a rotate of A by C1 bits. */
8782 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
8783 is a rotate of A by B bits. */
8784 {
8793 {
8812 {
8820 TYPE_PRECISION
8825 ? LROTATE_EXPR
8828 }
8830 {
8838 TYPE_PRECISION
8843 ? LROTATE_EXPR
8846 }
8847 }
8848 }
8850 associate:
8851 /* In most languages, can't associate operations on floats through
8852 parentheses. Rather than remember where the parentheses were, we
8853 don't associate floats at all, unless the user has specified
8854 -funsafe-math-optimizations. */
8857 {
8862 /* Split both trees into variables, constants, and literals. Then
8863 associate each group together, the constants with literals,
8864 then the result with variables. This increases the chances of
8865 literals being recombined later and of generating relocatable
8866 expressions for the sum of a constant and literal. */
8871 /* With undefined overflow we can only associate constants
8872 with one variable. */
8877 {
8885 /* The only case we can still associate with two variables
8886 is if they are the same, modulo negation. */
8889 }
8891 /* Only do something if we found more than two objects. Otherwise,
8892 nothing has changed and we risk infinite recursion. */
8898 {
8899 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
8908 /* Preserve the MINUS_EXPR if the negative part of the literal is
8909 greater than the positive part. Otherwise, the multiplicative
8910 folding code (i.e extract_muldiv) may be fooled in case
8911 unsigned constants are subtracted, like in the following
8912 example: ((X*2 + 4) - 8U)/2. */
8914 {
8918 {
8922 }
8923 else
8924 {
8928 }
8929 }
8931 {
8936 else
8937 {
8943 }
8944 }
8949 }
8950 }
8955 /* A - (-B) -> A + B */
8958 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
8966 /* Convert -A - 1 to ~A. */
8973 /* Convert -1 - A to ~A. */
8979 {
8985 /* Fold A - (A & B) into ~B & A. */
8988 {
8993 arg0);
8998 arg0);
8999 }
9001 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9002 any power of 2 minus 1. */
9007 {
9013 {
9017 }
9018 }
9019 }
9021 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9025 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9026 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9027 (-ARG1 + ARG0) reduces to -ARG1. */
9031 /* Fold &x - &x. This can happen from &x.foo - &x.
9032 This is unsafe for certain floats even in non-IEEE formats.
9033 In IEEE, it is unsafe because it does wrong for NaNs.
9034 Also note that operand_equal_p is always false if an operand
9035 is volatile. */
9041 /* A - B -> A + (-B) if B is easily negatable. */
9044 /* Avoid this transformation if B is a positive REAL_CST. */
9052 /* Try folding difference of addresses. */
9053 {
9054 HOST_WIDE_INT diff;
9060 }
9062 /* Fold &a[i] - &a[j] to i-j. */
9067 {
9072 {
9080 }
9081 }
9083 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9084 of the array. Loop optimizer sometimes produce this type of
9085 expressions. */
9087 {
9091 }
9099 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9100 same or one. */
9104 {
9108 }
9113 /* (-A) * (-B) -> A * B */
9124 {
9129 /* Transform x * -1 into -x. */
9133 /* (a * (1 << b)) is (a << b) */
9149 {
9152 "occur when simplifying "
9154 WARN_STRICT_OVERFLOW_MISC);
9156 }
9158 /* Optimize z * conj(z) for integer complex numbers. */
9165 }
9166 else
9167 {
9168 /* Maybe fold x * 0 to 0. The expressions aren't the same
9169 when x is NaN, since x * 0 is also NaN. Nor are they the
9170 same in modes with signed zeros, since multiplying a
9171 negative value by 0 gives -0, not +0. */
9176 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9181 /* Transform x * -1.0 into -x. */
9186 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9191 {
9197 }
9199 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9201 {
9204 {
9207 }
9208 }
9210 /* Optimize z * conj(z) for floating point complex numbers.
9211 Guarded by flag_unsafe_math_optimizations as non-finite
9212 imaginary components don't produce scalar results. */
9223 {
9227 /* Optimizations of root(...)*root(...). */
9229 {
9234 /* Optimize sqrt(x)*sqrt(x) as x. */
9240 /* Optimize root(x)*root(y) as root(x*y). */
9245 }
9247 /* Optimize expN(x)*expN(y) as expN(x+y). */
9249 {
9256 }
9258 /* Optimizations of pow(...)*pow(...). */
9262 {
9270 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9272 {
9277 arg01));
9279 }
9281 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9283 {
9288 arg));
9290 }
9291 }
9293 /* Optimize tan(x)*cos(x) as sin(x). */
9302 {
9308 }
9310 /* Optimize x*pow(x,c) as pow(x,c+1). */
9314 {
9321 {
9323 REAL_VALUE_TYPE c;
9332 }
9333 }
9335 /* Optimize pow(x,c)*x as pow(x,c+1). */
9339 {
9346 {
9348 REAL_VALUE_TYPE c;
9357 }
9358 }
9360 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9363 {
9367 {
9372 }
9373 }
9374 }
9375 }
9379 bit_ior:
9387 /* ~X | X is -1. */
9391 {
9395 }
9397 /* X | ~X is -1. */
9401 {
9405 }
9407 /* Canonicalize (X & C1) | C2. */
9411 {
9419 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9424 {
9428 }
9429 else
9430 {
9434 }
9436 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9441 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
9451 arg1);
9452 }
9454 /* (X & Y) | Y is (X, Y). */
9458 /* (X & Y) | X is (Y, X). */
9463 /* X | (X & Y) is (Y, X). */
9468 /* X | (Y & X) is (Y, X). */
9478 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
9480 This results in more efficient code for machines without a NAND
9481 instruction. Combine will canonicalize to the first form
9482 which will allow use of NAND instructions provided by the
9483 backend if they exist. */
9486 {
9491 }
9493 /* See if this can be simplified into a rotate first. If that
9494 is unsuccessful continue in the association code. */
9505 /* ~X ^ X is -1. */
9509 {
9513 }
9515 /* X ^ ~X is -1. */
9519 {
9523 }
9525 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
9526 with a constant, and the two constants have no bits in common,
9527 we should treat this as a BIT_IOR_EXPR since this may produce more
9528 simplifications. */
9536 {
9539 }
9541 /* (X | Y) ^ X -> Y & ~ X*/
9544 {
9547 arg1);
9551 }
9553 /* (Y | X) ^ X -> Y & ~ X*/
9556 {
9559 arg1);
9563 }
9565 /* X ^ (X | Y) -> Y & ~ X*/
9568 {
9571 arg0);
9575 }
9577 /* X ^ (Y | X) -> Y & ~ X*/
9580 {
9583 arg0);
9587 }
9589 /* Convert ~X ^ ~Y to X ^ Y. */
9596 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9603 /* Fold (X & Y) ^ Y as ~X & Y. */
9606 {
9611 }
9612 /* Fold (X & Y) ^ X as ~Y & X. */
9616 {
9621 }
9622 /* Fold X ^ (X & Y) as X & ~Y. */
9625 {
9630 }
9631 /* Fold X ^ (Y & X) as ~Y & X. */
9635 {
9640 }
9642 /* See if this can be simplified into a rotate first. If that
9643 is unsuccessful continue in the association code. */
9654 /* ~X & X is always zero. */
9659 /* X & ~X is always zero. */
9664 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
9674 /* (X | Y) & Y is (X, Y). */
9678 /* (X | Y) & X is (Y, X). */
9683 /* X & (X | Y) is (Y, X). */
9688 /* X & (Y | X) is (Y, X). */
9694 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9698 {
9704 }
9705 /* Fold ~X & 1 as (X & 1) == 0. */
9708 {
9714 }
9716 /* Fold (X ^ Y) & Y as ~X & Y. */
9719 {
9724 }
9725 /* Fold (X ^ Y) & X as ~Y & X. */
9729 {
9734 }
9735 /* Fold X & (X ^ Y) as X & ~Y. */
9738 {
9743 }
9744 /* Fold X & (Y ^ X) as ~Y & X. */
9748 {
9753 }
9758 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
9761 {
9762 unsigned int prec
9769 }
9771 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
9773 This results in more efficient code for machines without a NOR
9774 instruction. Combine will canonicalize to the first form
9775 which will allow use of NOR instructions provided by the
9776 backend if they exist. */
9779 {
9784 }
9789 /* Don't touch a floating-point divide by zero unless the mode
9790 of the constant can represent infinity. */
9796 /* Optimize A / A to 1.0 if we don't care about
9797 NaNs or Infinities. Skip the transformation
9798 for non-real operands. */
9803 {
9807 }
9809 /* The complex version of the above A / A optimization. */
9812 {
9816 {
9818 /* omit_two_operands will call fold_convert for us. */
9820 }
9821 }
9823 /* (-A) / (-B) -> A / B */
9833 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
9838 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
9843 /* If ARG1 is a constant, we can convert this to a multiply by the
9844 reciprocal. This does not have the same rounding properties,
9845 so only do this if -funsafe-math-optimizations. We can actually
9846 always safely do it if ARG1 is a power of two, but it's hard to
9847 tell if it is or not in a portable manner. */
9849 {
9854 /* Find the reciprocal if optimizing and the result is exact. */
9856 {
9857 REAL_VALUE_TYPE r;
9860 {
9864 }
9865 }
9866 }
9867 /* Convert A/B/C to A/(B*C). */
9874 /* Convert A/(B/C) to (A/B)*C. */
9882 /* Convert C1/(X*C2) into (C1/C2)/X. */
9887 {
9893 }
9896 {
9900 /* Optimize sin(x)/cos(x) as tan(x). */
9906 {
9912 }
9914 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
9920 {
9924 {
9929 }
9930 }
9932 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
9933 NaNs or Infinities. */
9937 {
9944 {
9950 }
9951 }
9953 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
9954 NaNs or Infinities. */
9958 {
9965 {
9969 {
9974 tmp);
9975 }
9976 }
9977 }
9979 /* Optimize pow(x,c)/x as pow(x,c-1). */
9983 {
9989 {
9991 REAL_VALUE_TYPE c;
10000 }
10001 }
10003 /* Optimize x/expN(y) into x*expN(-y). */
10005 {
10012 }
10014 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10018 {
10027 }
10028 }
10033 /* Simplify A / (B << N) where A and B are positive and B is
10034 a power of 2, to A >> (N + log2(B)). */
10039 {
10042 {
10049 WARN_STRICT_OVERFLOW_MISC);
10055 }
10056 }
10057 /* Fall thru */
10066 /* X / -1 is -X. */
10073 /* Convert -A / -B to A / B when the type is signed and overflow is
10074 undefined. */
10078 {
10081 "when distributing negation across "
10083 WARN_STRICT_OVERFLOW_MISC);
10086 }
10090 {
10093 "when distributing negation across "
10095 WARN_STRICT_OVERFLOW_MISC);
10098 }
10100 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10101 operation, EXACT_DIV_EXPR.
10103 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10104 At one time others generated faster code, it's not clear if they do
10105 after the last round to changes to the DIV code in expmed.c. */
10114 {
10118 WARN_STRICT_OVERFLOW_MISC);
10120 }
10128 /* X % 1 is always zero, but be sure to preserve any side
10129 effects in X. */
10133 /* X % 0, return X % 0 unchanged so that we can get the
10134 proper warnings and errors. */
10138 /* 0 % X is always zero, but be sure to preserve any side
10139 effects in X. Place this after checking for X == 0. */
10143 /* X % -1 is zero. */
10150 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10151 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10156 {
10158 /* Also optimize A % (C << N) where C is a power of 2,
10159 to A & ((C << N) - 1). */
10164 {
10169 "occur when simplifying "
10171 WARN_STRICT_OVERFLOW_MISC);
10175 }
10176 }
10178 /* X % -C is the same as X % C. */
10185 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10190 /* X % -Y is the same as X % Y. */
10201 {
10205 WARN_STRICT_OVERFLOW_MISC);
10207 }
10218 /* Optimize -1 >> x for arithmetic right shifts. */
10221 /* ... fall through ... */
10224 shift:
10230 /* Since negative shift count is not well-defined,
10231 don't try to compute it in the compiler. */
10235 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10240 {
10244 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10245 being well defined. */
10247 {
10252 else
10254 }
10258 }
10260 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10261 into x & ((unsigned)-1 >> c) for unsigned types. */
10269 {
10272 tree lshift;
10273 tree arg00;
10276 {
10283 }
10284 }
10286 /* Rewrite an LROTATE_EXPR by a constant into an
10287 RROTATE_EXPR by a new constant. */
10289 {
10295 }
10297 /* If we have a rotate of a bit operation with the rotate count and
10298 the second operand of the bit operation both constant,
10299 permute the two operations. */
10311 /* Two consecutive rotates adding up to the width of the mode can
10312 be ignored. */
10349 /* Note that the operands of this must be ints
10350 and their values must be 0 or 1.
10351 ("true" is a fixed value perhaps depending on the language.) */
10352 /* If first arg is constant zero, return it. */
10356 /* If either arg is constant true, drop it. */
10360 /* Preserve sequence points. */
10363 /* If second arg is constant zero, result is zero, but first arg
10364 must be evaluated. */
10367 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10368 case will be handled here. */
10372 /* !X && X is always false. */
10376 /* X && !X is always false. */
10381 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10382 means A >= Y && A != MAX, but in this case we know that
10383 A < X <= MAX. */
10387 {
10395 }
10397 truth_andor:
10398 /* We only do these simplifications if we are optimizing. */
10402 /* Check for things like (A || B) && (A || C). We can convert this
10403 to A || (B && C). Note that either operator can be any of the four
10404 truth and/or operations and the transformation will still be
10405 valid. Also note that we only care about order for the
10406 ANDIF and ORIF operators. If B contains side effects, this
10407 might change the truth-value of A. */
10414 {
10434 /* This case if tricky because we must either have commutative
10435 operators or else A10 must not have side-effects. */
10441 a01);
10442 }
10444 /* See if we can build a range comparison. */
10448 /* Check for the possibility of merging component references. If our
10449 lhs is another similar operation, try to merge its rhs with our
10450 rhs. Then try to merge our lhs and rhs. */
10462 /* Note that the operands of this must be ints
10463 and their values must be 0 or true.
10464 ("true" is a fixed value perhaps depending on the language.) */
10465 /* If first arg is constant true, return it. */
10469 /* If either arg is constant zero, drop it. */
10473 /* Preserve sequence points. */
10476 /* If second arg is constant true, result is true, but we must
10477 evaluate first arg. */
10480 /* Likewise for first arg, but note this only occurs here for
10481 TRUTH_OR_EXPR. */
10485 /* !X || X is always true. */
10489 /* X || !X is always true. */
10497 /* If the second arg is constant zero, drop it. */
10500 /* If the second arg is constant true, this is a logical inversion. */
10502 {
10503 /* Only call invert_truthvalue if operand is a truth value. */
10506 else
10509 }
10510 /* Identical arguments cancel to zero. */
10514 /* !X ^ X is always true. */
10519 /* X ^ !X is always true. */
10532 /* bool_var != 0 becomes bool_var. */
10537 /* bool_var == 1 becomes bool_var. */
10542 /* bool_var != 1 becomes !bool_var. */
10547 /* bool_var == 0 becomes !bool_var. */
10552 /* ~a != C becomes a != ~C where C is a constant. Likewise for ==. */
10555 {
10560 }
10562 /* If this is an equality comparison of the address of a non-weak
10563 object against zero, then we know the result. */
10570 /* If this is an equality comparison of the address of two non-weak,
10571 unaliased symbols neither of which are extern (since we do not
10572 have access to attributes for externs), then we know the result. */
10585 {
10586 /* We know that we're looking at the address of two
10587 non-weak, unaliased, static _DECL nodes.
10589 It is both wasteful and incorrect to call operand_equal_p
10590 to compare the two ADDR_EXPR nodes. It is wasteful in that
10591 all we need to do is test pointer equality for the arguments
10592 to the two ADDR_EXPR nodes. It is incorrect to use
10593 operand_equal_p as that function is NOT equivalent to a
10594 C equality test. It can in fact return false for two
10595 objects which would test as equal using the C equality
10596 operator. */
10600 type);
10601 }
10603 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
10604 a MINUS_EXPR of a constant, we can convert it into a comparison with
10605 a revised constant as long as no overflow occurs. */
10617 /* Similarly for a NEGATE_EXPR. */
10625 /* If we have X - Y == 0, we can convert that to X == Y and similarly
10626 for !=. Don't do this for ordered comparisons due to overflow. */
10632 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
10637 /* If this is an EQ or NE comparison with zero and ARG0 is
10638 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10639 two operations, but the latter can be done in one less insn
10640 on machines that have only two-operand insns or on which a
10641 constant cannot be the first operand. */
10644 {
10649 {
10656 }
10659 {
10666 }
10667 }
10669 /* If this is an NE or EQ comparison of zero against the result of a
10670 signed MOD operation whose second operand is a power of 2, make
10671 the MOD operation unsigned since it is simpler and equivalent. */
10679 {
10689 }
10691 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10692 C1 is a valid shift constant, and C2 is a power of two, i.e.
10693 a single bit. */
10697 == INTEGER_CST
10700 {
10705 /* Check for a valid shift count. */
10708 {
10712 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10713 can be rewritten as (X & (C2 << C1)) != 0. */
10715 {
10719 }
10720 /* Otherwise, for signed (arithmetic) shifts,
10721 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10722 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10726 /* Otherwise, of unsigned (logical) shifts,
10727 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10728 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10729 else
10733 arg000);
10734 }
10735 }
10737 /* If this is an NE comparison of zero with an AND of one, remove the
10738 comparison since the AND will give the correct value. */
10745 /* If we have (A & C) == C where C is a power of 2, convert this into
10746 (A & C) != 0. Similarly for NE_EXPR. */
10752 integer_zero_node));
10754 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
10755 bit, then fold the expression into A < 0 or A >= 0. */
10760 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10761 Similarly for NE_EXPR. */
10765 {
10774 }
10776 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
10777 Similarly for NE_EXPR. */
10781 {
10788 }
10790 /* If this is a comparison of a field, we may be able to simplify it. */
10794 /* Handle the constant case even without -O
10795 to make sure the warnings are given. */
10797 {
10801 }
10803 /* Optimize comparisons of strlen vs zero to a compare of the
10804 first character of the string vs zero. To wit,
10805 strlen(ptr) == 0 => *ptr == 0
10806 strlen(ptr) != 0 => *ptr != 0
10807 Other cases should reduce to one of these two (or a constant)
10808 due to the return value of strlen being unsigned. */
10811 {
10813 tree arglist;
10821 {
10825 }
10826 }
10828 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10829 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10833 {
10840 {
10842 {
10845 }
10848 }
10849 }
10851 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
10857 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
10862 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
10869 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
10877 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10878 (X & C) == 0 when C is a single bit. */
10883 {
10889 }
10891 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10892 constant C is a power of two, i.e. a single bit. */
10899 {
10903 }
10905 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10906 when is C is a power of two, i.e. a single bit. */
10913 {
10919 }
10923 {
10926 }
10937 /* Transform comparisons of the form X +- C CMP X. */
10944 {
10951 else
10954 /* (X - c) > X becomes false. */
10958 {
10962 "occur when assuming that (X - c) > X "
10964 WARN_STRICT_OVERFLOW_ALL);
10966 }
10968 /* Likewise (X + c) < X becomes false. */
10972 {
10976 "occur when assuming that "
10978 WARN_STRICT_OVERFLOW_ALL);
10980 }
10982 /* Convert (X - c) <= X to true. */
10987 {
10991 "occur when assuming that "
10993 WARN_STRICT_OVERFLOW_ALL);
10995 }
10997 /* Convert (X + c) >= X to true. */
11002 {
11006 "occur when assuming that "
11008 WARN_STRICT_OVERFLOW_ALL);
11010 }
11013 {
11014 /* Convert X + c > X and X - c < X to true for integers. */
11018 {
11021 "not occur when assuming that "
11023 WARN_STRICT_OVERFLOW_ALL);
11025 }
11030 {
11033 "not occur when assuming that "
11035 WARN_STRICT_OVERFLOW_ALL);
11037 }
11039 /* Convert X + c <= X and X - c >= X to false for integers. */
11043 {
11046 "not occur when assuming that "
11048 WARN_STRICT_OVERFLOW_ALL);
11050 }
11055 {
11058 "not occur when assuming that "
11060 WARN_STRICT_OVERFLOW_ALL);
11062 }
11063 }
11064 }
11066 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11067 This transformation affects the cases which are handled in later
11068 optimizations involving comparisons with non-negative constants. */
11072 {
11074 {
11079 }
11081 {
11086 }
11087 }
11089 /* Comparisons with the highest or lowest possible integer of
11090 the specified size will have known values. */
11091 {
11099 {
11100 HOST_WIDE_INT signed_max_hi;
11105 {
11112 {
11116 }
11117 else
11118 {
11122 }
11123 }
11124 else
11125 {
11134 {
11137 }
11138 else
11139 {
11142 }
11143 }
11148 {
11161 /* The GE_EXPR and LT_EXPR cases above are not normally
11162 reached because of previous transformations. */
11166 }
11168 == max_hi
11171 {
11176 arg1);
11181 arg1);
11184 }
11186 == min_hi
11189 {
11204 }
11206 == min_hi
11209 {
11214 arg1);
11219 arg1);
11222 }
11228 /* signed_type does not work on pointer types. */
11230 {
11231 /* The following case also applies to X < signed_max+1
11232 and X >= signed_max+1 because previous transformations. */
11234 {
11235 tree st;
11240 }
11241 }
11242 }
11243 }
11245 /* If we are comparing an ABS_EXPR with a constant, we can
11246 convert all the cases into explicit comparisons, but they may
11247 well not be faster than doing the ABS and one comparison.
11248 But ABS (X) <= C is a range comparison, which becomes a subtraction
11249 and a comparison, and is probably faster. */
11263 /* Convert ABS_EXPR<x> >= 0 to true. */
11270 {
11273 "when simplifying comparison of "
11275 WARN_STRICT_OVERFLOW_CONDITIONAL);
11277 }
11279 /* Convert ABS_EXPR<x> < 0 to false. */
11284 {
11287 "when simplifying comparison of "
11289 WARN_STRICT_OVERFLOW_CONDITIONAL);
11291 }
11293 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11294 and similarly for >= into !=. */
11310 return
11329 {
11333 }
11335 /* If the first operand is NaN, the result is constant. */
11339 {
11341 ? integer_zero_node
11344 }
11346 /* If the second operand is NaN, the result is constant. */
11350 {
11352 ? integer_zero_node
11355 }
11357 /* Simplify unordered comparison of something with itself. */
11363 && !flag_trapping_math
11367 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11368 {
11379 }
11384 /* When pedantic, a compound expression can be neither an lvalue
11385 nor an integer constant expression. */
11388 /* Don't let (0, 0) be null pointer constant. */
11402 /* An ASSERT_EXPR should never be passed to fold_binary. */
11408 }
11410 /* Callback for walk_tree, looking for LABEL_EXPR.
11411 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
11412 Do not check the sub-tree of GOTO_EXPR. */
11414 static tree
11418 {
11420 {
11425 /* no break */
11428 }
11429 }
11431 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
11432 accessible from outside the sub-tree. Returns NULL_TREE if no
11433 addressable label is found. */
11435 static bool
11437 {
11439 }
11441 /* Fold a ternary expression of code CODE and type TYPE with operands
11442 OP0, OP1, and OP2. Return the folded expression if folding is
11443 successful. Otherwise, return NULL_TREE. */
11445 tree
11447 {
11448 tree tem;
11455 /* Strip any conversions that don't change the mode. This is safe
11456 for every expression, except for a comparison expression because
11457 its signedness is derived from its operands. So, in the latter
11458 case, only strip conversions that don't change the signedness.
11460 Note that this is done as an internal manipulation within the
11461 constant folder, in order to find the simplest representation of
11462 the arguments so that their form can be studied. In any cases,
11463 the appropriate type conversions should be put back in the tree
11464 that will get out of the constant folder. */
11466 {
11469 }
11472 {
11475 }
11478 {
11482 {
11488 }
11492 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11493 so all simple results must be passed through pedantic_non_lvalue. */
11495 {
11498 /* Only optimize constant conditions when the selected branch
11499 has the same type as the COND_EXPR. This avoids optimizing
11500 away "c ? x : throw", where the throw has a void type.
11501 Avoid throwing away that operand which contains label. */
11508 }
11512 /* If we have A op B ? A : C, we may be able to convert this to a
11513 simpler expression, depending on the operation and the values
11514 of B and C. Signed zeros prevent all of these transformations,
11515 for reasons given above each one.
11517 Also try swapping the arguments and inverting the conditional. */
11522 {
11526 }
11530 op2,
11533 {
11536 {
11540 }
11541 }
11543 /* If the second operand is simpler than the third, swap them
11544 since that produces better jump optimization results. */
11547 {
11548 /* See if this can be inverted. If it can't, possibly because
11549 it was a floating-point inequality comparison, don't do
11550 anything. */
11554 }
11556 /* Convert A ? 1 : 0 to simply A. */
11559 /* If we try to convert OP0 to our type, the
11560 call to fold will try to move the conversion inside
11561 a COND, which will recurse. In that case, the COND_EXPR
11562 is probably the best choice, so leave it alone. */
11566 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11567 over COND_EXPR in cases such as floating point comparisons. */
11574 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11579 {
11580 /* sign_bit_p only checks ARG1 bits within A's precision.
11581 If <sign bit of A> has wider type than A, bits outside
11582 of A's precision in <sign bit of A> need to be checked.
11583 If they are all 0, this optimization needs to be done
11584 in unsigned A's type, if they are all 1 in signed A's type,
11585 otherwise this can't be done. */
11590 {
11592 HOST_WIDE_INT mask_hi;
11594 tree tem_type;
11602 {
11606 }
11607 else
11608 {
11612 }
11614 {
11618 }
11619 else
11625 {
11628 }
11631 {
11634 }
11635 else
11637 }
11644 arg1)));
11645 }
11647 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11648 already handled above. */
11653 {
11662 }
11664 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11665 is probably obsolete because the first operand should be a
11666 truth value (that's why we have the two cases above), but let's
11667 leave it in until we can confirm this for all front-ends. */
11678 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11684 arg1);
11686 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11690 {
11691 /* Only perform transformation if ARG0 is easily inverted. */
11696 arg1);
11697 }
11699 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11703 {
11704 /* Only perform transformation if ARG0 is easily inverted. */
11709 op2);
11710 }
11712 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11718 op2);
11723 /* Check for a built-in function. */
11735 {
11744 {
11750 else
11752 }
11753 }
11759 }
11761 /* Perform constant folding and related simplification of EXPR.
11762 The related simplifications include x*1 => x, x*0 => 0, etc.,
11763 and application of the associative law.
11764 NOP_EXPR conversions may be removed freely (as long as we
11765 are careful not to change the type of the overall expression).
11766 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11767 but we can constant-fold them if they have constant operands. */
11769 #ifdef ENABLE_FOLD_CHECKING
11770 # define fold(x) fold_1 (x)
11772 static
11773 #endif
11774 tree
11776 {
11780 tree tem;
11782 /* Return right away if a constant. */
11787 {
11792 {
11810 }
11811 }
11814 {
11821 }
11823 #ifdef ENABLE_FOLD_CHECKING
11824 #undef fold
11830 /* When --enable-checking=fold, compute a digest of expr before
11831 and after actual fold call to see if fold did not accidentally
11832 change original expr. */
11834 tree
11836 {
11837 tree ret;
11840 htab_t ht;
11859 }
11861 void
11863 {
11866 htab_t ht;
11876 }
11878 static void
11880 {
11882 }
11884 static void
11886 {
11892 recursive_label:
11906 {
11907 /* Allow DECL_ASSEMBLER_NAME to be modified. */
11911 }
11916 {
11917 /* Allow these fields to be modified. */
11924 {
11927 }
11928 }
11936 {
11939 {
11953 }
11957 {
11970 }
11986 {
11992 }
11997 {
12001 }
12012 {
12015 }
12025 }
12026 }
12028 #endif
12030 /* Fold a unary tree expression with code CODE of type TYPE with an
12031 operand OP0. Return a folded expression if successful. Otherwise,
12032 return a tree expression with code CODE of type TYPE with an
12033 operand OP0. */
12035 tree
12037 {
12038 tree tem;
12039 #ifdef ENABLE_FOLD_CHECKING
12042 htab_t ht;
12049 #endif
12055 #ifdef ENABLE_FOLD_CHECKING
12063 #endif
12065 }
12067 /* Fold a binary tree expression with code CODE of type TYPE with
12068 operands OP0 and OP1. Return a folded expression if successful.
12069 Otherwise, return a tree expression with code CODE of type TYPE
12070 with operands OP0 and OP1. */
12072 tree
12074 MEM_STAT_DECL)
12075 {
12076 tree tem;
12077 #ifdef ENABLE_FOLD_CHECKING
12083 htab_t ht;
12095 #endif
12101 #ifdef ENABLE_FOLD_CHECKING
12117 #endif
12119 }
12121 /* Fold a ternary tree expression with code CODE of type TYPE with
12122 operands OP0, OP1, and OP2. Return a folded expression if
12123 successful. Otherwise, return a tree expression with code CODE of
12124 type TYPE with operands OP0, OP1, and OP2. */
12126 tree
12128 MEM_STAT_DECL)
12129 {
12130 tree tem;
12131 #ifdef ENABLE_FOLD_CHECKING
12139 htab_t ht;
12156 #endif
12162 #ifdef ENABLE_FOLD_CHECKING
12186 #endif
12188 }
12190 /* Perform constant folding and related simplification of initializer
12191 expression EXPR. These behave identically to "fold_buildN" but ignore
12192 potential run-time traps and exceptions that fold must preserve. */
12194 #define START_FOLD_INIT \
12195 int saved_signaling_nans = flag_signaling_nans;\
12196 int saved_trapping_math = flag_trapping_math;\
12197 int saved_rounding_math = flag_rounding_math;\
12198 int saved_trapv = flag_trapv;\
12199 int saved_folding_initializer = folding_initializer;\
12200 flag_signaling_nans = 0;\
12201 flag_trapping_math = 0;\
12202 flag_rounding_math = 0;\
12203 flag_trapv = 0;\
12204 folding_initializer = 1;
12206 #define END_FOLD_INIT \
12207 flag_signaling_nans = saved_signaling_nans;\
12208 flag_trapping_math = saved_trapping_math;\
12209 flag_rounding_math = saved_rounding_math;\
12210 flag_trapv = saved_trapv;\
12211 folding_initializer = saved_folding_initializer;
12213 tree
12215 {
12216 tree result;
12217 START_FOLD_INIT;
12221 END_FOLD_INIT;
12223 }
12225 tree
12227 {
12228 tree result;
12229 START_FOLD_INIT;
12233 END_FOLD_INIT;
12235 }
12237 tree
12239 tree op2)
12240 {
12241 tree result;
12242 START_FOLD_INIT;
12246 END_FOLD_INIT;
12248 }
12250 #undef START_FOLD_INIT
12251 #undef END_FOLD_INIT
12253 /* Determine if first argument is a multiple of second argument. Return 0 if
12254 it is not, or we cannot easily determined it to be.
12256 An example of the sort of thing we care about (at this point; this routine
12257 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12258 fold cases do now) is discovering that
12260 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12262 is a multiple of
12264 SAVE_EXPR (J * 8)
12266 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12268 This code also handles discovering that
12270 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12272 is a multiple of 8 so we don't have to worry about dealing with a
12273 possible remainder.
12275 Note that we *look* inside a SAVE_EXPR only to determine how it was
12276 calculated; it is not safe for fold to do much of anything else with the
12277 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12278 at run time. For example, the latter example above *cannot* be implemented
12279 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12280 evaluation time of the original SAVE_EXPR is not necessarily the same at
12281 the time the new expression is evaluated. The only optimization of this
12282 sort that would be valid is changing
12284 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12286 divided by 8 to
12288 SAVE_EXPR (I) * SAVE_EXPR (J)
12290 (where the same SAVE_EXPR (J) is used in the original and the
12291 transformed version). */
12293 static int
12295 {
12303 {
12305 /* Bitwise and provides a power of two multiple. If the mask is
12306 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12309 /* FALLTHRU */
12322 {
12326 /* const_binop may not detect overflow correctly,
12327 so check for it explicitly here. */
12333 size_one_node,
12337 }
12341 /* Can't handle conversions from non-integral or wider integral type. */
12347 /* .. fall through ... */
12363 }
12364 }
12366 /* Return true if `t' is known to be non-negative. If the return
12367 value is based on the assumption that signed overflow is undefined,
12368 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12369 *STRICT_OVERFLOW_P. */
12371 int
12373 {
12381 {
12383 /* Query VRP to see if it has recorded any information about
12384 the range of this object. */
12388 /* We can't return 1 if flag_wrapv is set because
12389 ABS_EXPR<INT_MIN> = INT_MIN. */
12393 {
12396 }
12408 strict_overflow_p)
12410 strict_overflow_p));
12412 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12413 both unsigned and at least 2 bits shorter than the result. */
12417 {
12422 {
12426 }
12427 }
12432 {
12433 /* x * x for floating point x is always non-negative. */
12437 strict_overflow_p)
12439 strict_overflow_p));
12440 }
12442 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12443 both unsigned and their total bits is shorter than the result. */
12447 {
12454 }
12460 strict_overflow_p)
12462 strict_overflow_p));
12473 strict_overflow_p)
12475 strict_overflow_p));
12486 strict_overflow_p);
12491 strict_overflow_p);
12495 strict_overflow_p);
12499 strict_overflow_p)
12501 strict_overflow_p));
12504 {
12509 {
12512 strict_overflow_p);
12514 {
12518 strict_overflow_p);
12519 }
12520 }
12522 {
12525 strict_overflow_p);
12529 }
12530 }
12534 {
12538 /* If the initializer is non-void, then it's a normal expression
12539 that will be assigned to the slot. */
12543 /* Otherwise, the initializer sets the slot in some way. One common
12544 way is an assignment statement at the end of the initializer. */
12546 {
12554 else
12556 }
12560 strict_overflow_p);
12563 }
12566 {
12571 {
12587 /* Always true. */
12591 /* sqrt(-0.0) is -0.0. */
12595 strict_overflow_p);
12625 /* True if the 1st argument is nonnegative. */
12627 strict_overflow_p);
12630 /* True if the 1st OR 2nd arguments are nonnegative. */
12632 strict_overflow_p)
12633 || (tree_expr_nonnegative_warnv_p
12635 strict_overflow_p)));
12638 /* True if the 1st AND 2nd arguments are nonnegative. */
12640 strict_overflow_p)
12641 && (tree_expr_nonnegative_warnv_p
12643 strict_overflow_p)));
12646 /* True if the 2nd argument is nonnegative. */
12649 strict_overflow_p));
12653 }
12654 }
12656 /* ... fall through ... */
12659 {
12663 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12664 have a signed:1 type (where the value is -1 and 0). */
12666 }
12667 }
12669 /* We don't know sign of `t', so be conservative and return false. */
12671 }
12673 /* Return true if `t' is known to be non-negative. Handle warnings
12674 about undefined signed overflow. */
12676 int
12678 {
12686 "determining that expression is always "
12688 WARN_STRICT_OVERFLOW_MISC);
12690 }
12692 /* Return true when T is an address and is known to be nonzero.
12693 For floating point we further ensure that T is not denormal.
12694 Similar logic is present in nonzero_address in rtlanal.h.
12696 If the return value is based on the assumption that signed overflow
12697 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
12698 change *STRICT_OVERFLOW_P. */
12700 bool
12702 {
12706 /* Doing something useful for floating point would need more work. */
12711 {
12713 /* Query VRP to see if it has recorded any information about
12714 the range of this object. */
12719 strict_overflow_p);
12722 /* We used to test for !integer_zerop here. This does not work correctly
12723 if TREE_CONSTANT_OVERFLOW (t). */
12729 {
12730 /* With the presence of negative values it is hard
12731 to say something. */
12738 /* One of operands must be positive and the other non-negative. */
12739 /* We don't set *STRICT_OVERFLOW_P here: even if this value
12740 overflows, on a twos-complement machine the sum of two
12741 nonnegative numbers can never be zero. */
12743 strict_overflow_p)
12745 strict_overflow_p));
12746 }
12751 {
12753 strict_overflow_p)
12755 strict_overflow_p))
12756 {
12759 }
12760 }
12764 {
12770 strict_overflow_p));
12771 }
12775 {
12781 /* Weak declarations may link to NULL. */
12785 /* Constants are never weak. */
12790 }
12798 {
12802 }
12811 {
12814 }
12821 {
12825 /* When both operands are nonzero, then MAX must be too. */
12827 strict_overflow_p))
12830 /* MAX where operand 0 is positive is positive. */
12832 strict_overflow_p);
12833 }
12834 /* MAX where operand 1 is positive is positive. */
12839 {
12843 }
12850 strict_overflow_p);
12855 strict_overflow_p);
12859 strict_overflow_p)
12861 strict_overflow_p));
12868 }
12870 }
12872 /* Return true when T is an address and is known to be nonzero.
12873 Handle warnings about undefined signed overflow. */
12875 bool
12877 {
12884 "determining that expression is always "
12886 WARN_STRICT_OVERFLOW_MISC);
12888 }
12890 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
12891 attempt to fold the expression to a constant without modifying TYPE,
12892 OP0 or OP1.
12894 If the expression could be simplified to a constant, then return
12895 the constant. If the expression would not be simplified to a
12896 constant, then return NULL_TREE. */
12898 tree
12900 {
12903 }
12905 /* Given the components of a unary expression CODE, TYPE and OP0,
12906 attempt to fold the expression to a constant without modifying
12907 TYPE or OP0.
12909 If the expression could be simplified to a constant, then return
12910 the constant. If the expression would not be simplified to a
12911 constant, then return NULL_TREE. */
12913 tree
12915 {
12918 }
12920 /* If EXP represents referencing an element in a constant string
12921 (either via pointer arithmetic or array indexing), return the
12922 tree representing the value accessed, otherwise return NULL. */
12924 tree
12926 {
12930 {
12932 tree index;
12933 tree string;
12937 else
12938 {
12942 /* Optimize the special-case of a zero lower bound.
12944 We convert the low_bound to sizetype to avoid some problems
12945 with constant folding. (E.g. suppose the lower bound is 1,
12946 and its mode is QI. Without the conversion,l (ARRAY
12947 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
12948 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
12953 }
12967 }
12969 }
12971 /* Return the tree for neg (ARG0) when ARG0 is known to be either
12972 an integer constant or real constant.
12974 TYPE is the type of the result. */
12976 static tree
12978 {
12982 {
12984 {
12986 HOST_WIDE_INT high;
12996 }
13004 }
13007 }
13009 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13010 an integer constant or real constant.
13012 TYPE is the type of the result. */
13014 tree
13016 {
13020 {
13022 /* If the value is unsigned, then the absolute value is
13023 the same as the ordinary value. */
13026 /* Similarly, if the value is non-negative. */
13029 /* If the value is negative, then the absolute value is
13030 its negation. */
13031 else
13032 {
13034 HOST_WIDE_INT high;
13041 }
13047 else
13053 }
13056 }
13058 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13059 constant. TYPE is the type of the result. */
13061 static tree
13063 {
13075 }
13077 /* Given CODE, a relational operator, the target type, TYPE and two
13078 constant operands OP0 and OP1, return the result of the
13079 relational operation. If the result is not a compile time
13080 constant, then return NULL_TREE. */
13082 static tree
13084 {
13087 /* From here on, the only cases we handle are when the result is
13088 known to be a constant. */
13091 {
13095 /* Handle the cases where either operand is a NaN. */
13097 {
13099 {
13127 }
13130 }
13133 }
13135 /* Handle equality/inequality of complex constants. */
13137 {
13148 else
13150 }
13152 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13154 To compute GT, swap the arguments and do LT.
13155 To compute GE, do LT and invert the result.
13156 To compute LE, swap the arguments, do LT and invert the result.
13157 To compute NE, do EQ and invert the result.
13159 Therefore, the code below must handle only EQ and LT. */
13162 {
13167 }
13169 /* Note that it is safe to invert for real values here because we
13170 have already handled the one case that it matters. */
13174 {
13177 }
13179 /* Compute a result for LT or EQ if args permit;
13180 Otherwise return T. */
13182 {
13187 else
13189 }
13190 else
13196 }
13198 /* Build an expression for the a clean point containing EXPR with type TYPE.
13199 Don't build a cleanup point expression for EXPR which don't have side
13200 effects. */
13202 tree
13204 {
13205 /* If the expression does not have side effects then we don't have to wrap
13206 it with a cleanup point expression. */
13210 /* If the expression is a return, check to see if the expression inside the
13211 return has no side effects or the right hand side of the modify expression
13212 inside the return. If either don't have side effects set we don't need to
13213 wrap the expression in a cleanup point expression. Note we don't check the
13214 left hand side of the modify because it should always be a return decl. */
13216 {
13223 }
13226 }
13228 /* Build an expression for the address of T. Folds away INDIRECT_REF to
13229 avoid confusing the gimplify process. */
13231 tree
13233 {
13234 /* The size of the object is not relevant when talking about its address. */
13238 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
13241 {
13245 }
13246 else
13247 {
13256 }
13259 }
13261 tree
13263 {
13265 }
13267 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13268 of an indirection through OP0, or NULL_TREE if no simplification is
13269 possible. */
13271 tree
13273 {
13275 tree subtype;
13283 {
13286 /* *&CONST_DECL -> to the value of the const decl. */
13289 /* *&p => p; make sure to handle *&"str"[cst] here. */
13291 {
13295 else
13297 }
13298 /* *(foo *)&fooarray => fooarray[0] */
13301 {
13307 }
13308 /* *(foo *)&complexfoo => __real__ complexfoo */
13312 }
13314 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13317 {
13320 tree op00type;
13327 {
13331 }
13332 }
13334 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
13337 {
13338 tree type_domain;
13345 }
13348 }
13350 /* Builds an expression for an indirection through T, simplifying some
13351 cases. */
13353 tree
13355 {
13361 else
13363 }
13365 /* Given an INDIRECT_REF T, return either T or a simplified version. */
13367 tree
13369 {
13374 else
13376 }
13378 /* Strip non-trapping, non-side-effecting tree nodes from an expression
13379 whose result is ignored. The type of the returned tree need not be
13380 the same as the original expression. */
13382 tree
13384 {
13390 {
13401 else
13407 {
13423 }
13428 }
13429 }
13431 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
13432 This can only be applied to objects of a sizetype. */
13434 tree
13436 {
13443 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
13444 have to do anything. Only do this when we are not given a const,
13445 because in that case, this check is more expensive than just
13446 doing it. */
13448 {
13453 }
13455 /* If divisor is a power of two, simplify this to bit manipulation. */
13457 {
13458 tree t;
13464 }
13465 else
13466 {
13471 }
13474 }
13476 /* Likewise, but round down. */
13478 tree
13480 {
13487 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
13488 have to do anything. Only do this when we are not given a const,
13489 because in that case, this check is more expensive than just
13490 doing it. */
13492 {
13497 }
13499 /* If divisor is a power of two, simplify this to bit manipulation. */
13501 {
13502 tree t;
13506 }
13507 else
13508 {
13513 }
13516 }
13518 /* Returns the pointer to the base of the object addressed by EXP and
13519 extracts the information about the offset of the access, storing it
13520 to PBITPOS and POFFSET. */
13522 static tree
13525 {
13526 tree core;
13529 HOST_WIDE_INT bitsize;
13532 {
13537 }
13538 else
13539 {
13543 }
13546 }
13548 /* Returns true if addresses of E1 and E2 differ by a constant, false
13549 otherwise. If they do, E1 - E2 is stored in *DIFF. */
13551 bool
13553 {
13567 {
13577 }
13579 {
13580 /* If only one of the offsets is non-constant, the difference cannot
13581 be a constant. */
13583 }
13584 else
13589 }
13591 /* Simplify the floating point expression EXP when the sign of the
13592 result is not significant. Return NULL_TREE if no simplification
13593 is possible. */
13595 tree
13597 {
13601 {
13621 }
13623 }