| blob | c74f8910374a97a3388d622cdf70210a8fcfd554 |
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 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
10 version.
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 for more details.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
20 02110-1301, USA. */
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. */
62 /* The following constants represent a bit based encoding of GCC's
63 comparison operators. This encoding simplifies transformations
64 on relational comparison operators, such as AND and OR. */
82 };
114 tree);
136 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
137 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
138 and SUM1. Then this yields nonzero if overflow occurred during the
139 addition.
141 Overflow occurs if A and B have the same sign, but A and SUM differ in
142 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
143 sign. */
144 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
145 \f
146 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
147 We do that by representing the two-word integer in 4 words, with only
148 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
149 number. The value of the word is LOWPART + HIGHPART * BASE. */
151 #define LOWPART(x) \
152 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
153 #define HIGHPART(x) \
154 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
155 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
157 /* Unpack a two-word integer into 4 words.
158 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
159 WORDS points to the array of HOST_WIDE_INTs. */
161 static void
163 {
168 }
170 /* Pack an array of 4 words into a two-word integer.
171 WORDS points to the array of words.
172 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
174 static void
177 {
180 }
181 \f
182 /* T is an INT_CST node. OVERFLOWABLE indicates if we are interested
183 in overflow of the value, when >0 we are only interested in signed
184 overflow, for <0 we are interested in any overflow. OVERFLOWED
185 indicates whether overflow has already occurred. CONST_OVERFLOWED
186 indicates whether constant overflow has already occurred. We force
187 T's value to be within range of T's type (by setting to 0 or 1 all
188 the bits outside the type's range). We set TREE_OVERFLOWED if,
189 OVERFLOWED is nonzero,
190 or OVERFLOWABLE is >0 and signed overflow occurs
191 or OVERFLOWABLE is <0 and any overflow occurs
192 We set TREE_CONSTANT_OVERFLOWED if,
193 CONST_OVERFLOWED is nonzero
194 or we set TREE_OVERFLOWED.
195 We return either the original T, or a copy. */
197 tree
200 {
202 HOST_WIDE_INT high;
214 else
216 /* Size types *are* sign extended. */
221 /* First clear all bits that are beyond the type's precision. */
224 ;
227 else
228 {
232 }
239 {
240 /* Sign extend top half? */
244 }
246 {
249 }
250 else
251 {
252 /* Sign extend bottom half? */
254 {
257 }
258 }
260 /* If the value changed, return a new node. */
263 {
269 {
273 }
275 {
278 }
279 }
282 }
283 \f
284 /* Add two doubleword integers with doubleword result.
285 Each argument is given as two `HOST_WIDE_INT' pieces.
286 One argument is L1 and H1; the other, L2 and H2.
287 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
289 int
293 {
295 HOST_WIDE_INT h;
303 }
305 /* Negate a doubleword integer with doubleword result.
306 Return nonzero if the operation overflows, assuming it's signed.
307 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
308 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
310 int
313 {
315 {
319 }
320 else
321 {
325 }
326 }
327 \f
328 /* Multiply two doubleword integers with doubleword result.
329 Return nonzero if the operation overflows, assuming it's signed.
330 Each argument is given as two `HOST_WIDE_INT' pieces.
331 One argument is L1 and H1; the other, L2 and H2.
332 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
334 int
338 {
353 {
356 {
358 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
360 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
364 }
366 }
370 /* Check for overflow by calculating the top half of the answer in full;
371 it should agree with the low half's sign bit. */
374 {
377 }
379 {
382 }
384 }
385 \f
386 /* Shift the doubleword integer in L1, H1 left by COUNT places
387 keeping only PREC bits of result.
388 Shift right if COUNT is negative.
389 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
390 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
392 void
396 {
400 {
403 }
409 {
410 /* Shifting by the host word size is undefined according to the
411 ANSI standard, so we must handle this as a special case. */
414 }
416 {
419 }
420 else
421 {
425 }
427 /* Sign extend all bits that are beyond the precision. */
435 ;
437 {
440 }
441 else
442 {
446 }
447 }
449 /* Shift the doubleword integer in L1, H1 right by COUNT places
450 keeping only PREC bits of result. COUNT must be positive.
451 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
452 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
454 void
459 {
462 signmask = (arith
470 {
471 /* Shifting by the host word size is undefined according to the
472 ANSI standard, so we must handle this as a special case. */
475 }
477 {
480 }
481 else
482 {
486 }
488 /* Zero / sign extend all bits that are beyond the precision. */
491 {
494 }
496 ;
498 {
501 }
502 else
503 {
507 }
508 }
509 \f
510 /* Rotate the doubleword integer in L1, H1 left by COUNT places
511 keeping only PREC bits of result.
512 Rotate right if COUNT is negative.
513 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
515 void
519 {
531 }
533 /* Rotate the doubleword integer in L1, H1 left by COUNT places
534 keeping only PREC bits of result. COUNT must be positive.
535 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
537 void
541 {
553 }
554 \f
555 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
556 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
557 CODE is a tree code for a kind of division, one of
558 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
559 or EXACT_DIV_EXPR
560 It controls how the quotient is rounded to an integer.
561 Return nonzero if the operation overflows.
562 UNS nonzero says do unsigned division. */
564 int
567 HOST_WIDE_INT hnum_orig,
569 HOST_WIDE_INT hden_orig,
573 {
589 /* Calculate quotient sign and convert operands to unsigned. */
591 {
593 {
595 /* (minimum integer) / (-1) is the only overflow case. */
599 }
601 {
604 }
605 }
610 /* This unsigned division rounds toward zero. */
613 }
617 /* hden != 0 already checked. */
622 }
632 /* Special code for when the divisor < BASE. */
634 {
635 /* hnum != 0 already checked. */
637 {
641 }
642 }
643 else
644 {
645 /* Full double precision division,
646 with thanks to Don Knuth's "Seminumerical Algorithms". */
650 /* Find the highest nonzero divisor digit. */
653 {
656 }
658 /* Insure that the first digit of the divisor is at least BASE/2.
659 This is required by the quotient digit estimation algorithm. */
666 {
670 }
675 {
680 }
681 }
685 /* Main loop */
687 {
688 /* Guess the next quotient digit, quo_est, by dividing the first
689 two remaining dividend digits by the high order quotient digit.
690 quo_est is never low and is at most 2 high. */
697 else
700 /* Refine quo_est so it's usually correct, and at most one high. */
705 quo_est--;
707 /* Try QUO_EST as the quotient digit, by multiplying the
708 divisor by QUO_EST and subtracting from the remaining dividend.
709 Keep in mind that QUO_EST is the I - 1st digit. */
713 {
719 }
721 /* If quo_est was high by one, then num[i] went negative and
722 we need to correct things. */
724 {
725 quo_est--;
728 {
732 }
735 }
737 /* Store the quotient digit. */
739 }
740 }
744 finish_up:
745 /* If result is negative, make it so. */
749 /* Compute trial remainder: rem = num - (quo * den) */
755 {
764 {
765 /* quo = quo - 1; */
768 }
769 else
776 {
779 }
780 else
786 {
792 /* Get absolute values. */
798 /* If (2 * abs (lrem) >= abs (lden)) */
807 {
809 /* quo = quo - 1; */
812 else
813 /* quo = quo + 1; */
816 }
817 else
819 }
824 }
826 /* Compute true remainder: rem = num - (quo * den) */
831 }
833 /* If ARG2 divides ARG1 with zero remainder, carries out the division
834 of type CODE and returns the quotient.
835 Otherwise returns NULL_TREE. */
837 static tree
839 {
858 }
859 \f
860 /* Return true if built-in mathematical function specified by CODE
861 preserves the sign of it argument, i.e. -f(x) == f(-x). */
863 static bool
865 {
867 {
884 }
886 }
888 /* Check whether we may negate an integer constant T without causing
889 overflow. */
891 bool
893 {
896 tree type;
906 {
911 }
912 else
917 }
919 /* Determine whether an expression T can be cheaply negated using
920 the function negate_expr. */
922 static bool
924 {
925 tree type;
934 {
939 /* Check that -CST will not overflow type. */
953 /* -(A + B) -> (-B) - A. */
958 /* -(A + B) -> (-A) - B. */
962 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
971 /* Fall through. */
980 /* Negate -((double)float) as (double)(-float). */
982 {
986 }
990 /* Negate -f(x) as f(-x). */
996 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
998 {
1004 }
1009 }
1011 }
1013 /* Given T, an expression, return the negation of T. Allow for T to be
1014 null, in which case return null. */
1016 static tree
1018 {
1019 tree type;
1020 tree tem;
1029 {
1040 /* Two's complement FP formats, such as c4x, may overflow. */
1046 {
1055 }
1063 {
1064 /* -(A + B) -> (-B) - A. */
1068 {
1073 }
1075 /* -(A + B) -> (-A) - B. */
1077 {
1082 }
1083 }
1087 /* - (A - B) -> B - A */
1100 /* Fall through. */
1104 {
1117 }
1121 /* Convert -((double)float) into (double)(-float). */
1123 {
1127 }
1131 /* Negate -f(x) as f(-x). */
1134 {
1141 }
1145 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1147 {
1152 {
1159 }
1160 }
1165 }
1169 }
1170 \f
1171 /* Split a tree IN into a constant, literal and variable parts that could be
1172 combined with CODE to make IN. "constant" means an expression with
1173 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1174 commutative arithmetic operation. Store the constant part into *CONP,
1175 the literal in *LITP and return the variable part. If a part isn't
1176 present, set it to null. If the tree does not decompose in this way,
1177 return the entire tree as the variable part and the other parts as null.
1179 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1180 case, we negate an operand that was subtracted. Except if it is a
1181 literal for which we use *MINUS_LITP instead.
1183 If NEGATE_P is true, we are negating all of IN, again except a literal
1184 for which we use *MINUS_LITP instead.
1186 If IN is itself a literal or constant, return it as appropriate.
1188 Note that we do not guarantee that any of the three values will be the
1189 same type as IN, but they will have the same signedness and mode. */
1191 static tree
1194 {
1201 /* Strip any conversions that don't change the machine mode or signedness. */
1208 /* We can associate addition and subtraction together (even
1209 though the C standard doesn't say so) for integers because
1210 the value is not affected. For reals, the value might be
1211 affected, so we can't. */
1214 {
1220 /* First see if either of the operands is a literal, then a constant. */
1231 /* If we haven't dealt with either operand, this is not a case we can
1232 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1237 else
1240 /* Now do any needed negations. */
1247 }
1250 else
1254 {
1261 }
1264 }
1266 /* Re-associate trees split by the above function. T1 and T2 are either
1267 expressions to associate or null. Return the new expression, if any. If
1268 we build an operation, do it in TYPE and with CODE. */
1270 static tree
1272 {
1278 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1279 try to fold this since we will have infinite recursion. But do
1280 deal with any NEGATE_EXPRs. */
1283 {
1285 {
1294 }
1296 {
1299 }
1303 }
1307 }
1308 \f
1309 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1310 to produce a new constant.
1312 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1314 tree
1316 {
1320 HOST_WIDE_INT hi;
1322 HOST_WIDE_INT garbageh;
1323 tree t;
1326 int is_sizetype
1336 {
1352 /* It's unclear from the C standard whether shifts can overflow.
1353 The following code ignores overflow; perhaps a C standard
1354 interpretation ruling is needed. */
1383 /* This is a shortcut for a common special case. */
1388 {
1394 }
1396 /* ... fall through ... */
1400 {
1403 }
1406 {
1409 }
1416 /* This is a shortcut for a common special case. */
1421 {
1426 }
1428 /* ... fall through ... */
1444 else
1450 else
1456 }
1461 {
1462 /* Propagate overflow flags ourselves. */
1465 {
1469 }
1471 {
1474 }
1475 }
1476 else
1484 }
1486 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1487 constant. We assume ARG1 and ARG2 have the same data type, or at least
1488 are the same kind of constant and the same machine mode.
1490 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1492 static tree
1494 {
1502 {
1504 REAL_VALUE_TYPE d1;
1505 REAL_VALUE_TYPE d2;
1506 REAL_VALUE_TYPE value;
1507 REAL_VALUE_TYPE result;
1517 /* Don't perform operation if we honor signaling NaNs and
1518 either operand is a NaN. */
1523 /* Don't perform operation if it would raise a division
1524 by zero exception. */
1530 /* If either operand is a NaN, just return it. Otherwise, set up
1531 for floating-point trap; we return an overflow. */
1540 /* Don't constant fold this floating point operation if the
1541 result may dependent upon the run-time rounding mode and
1542 flag_rounding_math is set, or if GCC's software emulation
1543 is unable to accurately represent the result. */
1559 }
1561 {
1567 tree t;
1570 {
1590 notrunc),
1596 notrunc));
1600 {
1602 tree magsquared
1606 notrunc);
1611 notrunc);
1615 notrunc);
1618 {
1621 }
1622 else
1623 {
1628 }
1631 }
1636 }
1638 }
1640 }
1642 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1643 indicates which particular sizetype to create. */
1645 tree
1647 {
1649 }
1650 \f
1651 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1652 is a tree code. The type of the result is taken from the operands.
1653 Both must be the same type integer type and it must be a size type.
1654 If the operands are constant, so is the result. */
1656 tree
1658 {
1664 /* Handle the special case of two integer constants faster. */
1666 {
1667 /* And some specific cases even faster than that. */
1676 /* Handle general case of two integer constants. */
1678 }
1684 }
1686 /* Given two values, either both of sizetype or both of bitsizetype,
1687 compute the difference between the two values. Return the value
1688 in signed type corresponding to the type of the operands. */
1690 tree
1692 {
1694 tree ctype;
1699 /* If the type is already signed, just do the simple thing. */
1705 /* If either operand is not a constant, do the conversions to the signed
1706 type and subtract. The hardware will do the right thing with any
1707 overflow in the subtraction. */
1712 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1713 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1714 overflow) and negate (which can't either). Special-case a result
1715 of zero while we're here. */
1720 else
1724 }
1725 \f
1726 /* A subroutine of fold_convert_const handling conversions of an
1727 INTEGER_CST to another integer type. */
1729 static tree
1731 {
1732 tree t;
1734 /* Given an integer constant, make new constant with new type,
1735 appropriately sign-extended or truncated. */
1740 /* Don't set the overflow when
1741 converting a pointer */
1750 }
1752 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1753 to an integer type. */
1755 static tree
1757 {
1759 tree t;
1761 /* The following code implements the floating point to integer
1762 conversion rules required by the Java Language Specification,
1763 that IEEE NaNs are mapped to zero and values that overflow
1764 the target precision saturate, i.e. values greater than
1765 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1766 are mapped to INT_MIN. These semantics are allowed by the
1767 C and C++ standards that simply state that the behavior of
1768 FP-to-integer conversion is unspecified upon overflow. */
1771 REAL_VALUE_TYPE r;
1775 {
1794 }
1796 /* If R is NaN, return zero and show we have an overflow. */
1798 {
1802 }
1804 /* See if R is less than the lower bound or greater than the
1805 upper bound. */
1808 {
1812 {
1816 }
1817 }
1820 {
1823 {
1826 {
1830 }
1831 }
1832 }
1842 }
1844 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1845 to another floating point type. */
1847 static tree
1849 {
1850 REAL_VALUE_TYPE value;
1851 tree t;
1860 }
1862 /* Attempt to fold type conversion operation CODE of expression ARG1 to
1863 type TYPE. If no simplification can be done return NULL_TREE. */
1865 static tree
1867 {
1872 {
1877 }
1879 {
1884 }
1886 }
1888 /* Construct a vector of zero elements of vector type TYPE. */
1890 static tree
1892 {
1903 }
1905 /* Convert expression ARG to type TYPE. Used by the middle-end for
1906 simple conversions in preference to calling the front-end's convert. */
1908 tree
1910 {
1912 tree tem;
1928 {
1933 {
1937 }
1942 {
1945 }
1952 {
1956 }
1958 {
1962 }
1965 {
1981 }
1985 {
1994 {
1998 {
2002 }
2010 }
2014 }
2029 }
2030 }
2031 \f
2032 /* Return false if expr can be assumed not to be an lvalue, true
2033 otherwise. */
2035 static bool
2037 {
2038 /* We only need to wrap lvalue tree codes. */
2040 {
2074 /* Assume the worst for front-end tree codes. */
2078 }
2081 }
2083 /* Return an expr equal to X but certainly not valid as an lvalue. */
2085 tree
2087 {
2088 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2089 us. */
2096 }
2098 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2099 Zero means allow extended lvalues. */
2103 /* When pedantic, return an expr equal to X but certainly not valid as a
2104 pedantic lvalue. Otherwise, return X. */
2106 static tree
2108 {
2111 else
2113 }
2114 \f
2115 /* Given a tree comparison code, return the code that is the logical inverse
2116 of the given code. It is not safe to do this for floating-point
2117 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2118 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2120 enum tree_code
2122 {
2127 {
2158 }
2159 }
2161 /* Similar, but return the comparison that results if the operands are
2162 swapped. This is safe for floating-point. */
2164 enum tree_code
2166 {
2168 {
2194 }
2195 }
2198 /* Convert a comparison tree code from an enum tree_code representation
2199 into a compcode bit-based encoding. This function is the inverse of
2200 compcode_to_comparison. */
2202 static enum comparison_code
2204 {
2206 {
2237 }
2238 }
2240 /* Convert a compcode bit-based encoding of a comparison operator back
2241 to GCC's enum tree_code representation. This function is the
2242 inverse of comparison_to_compcode. */
2244 static enum tree_code
2246 {
2248 {
2279 }
2280 }
2282 /* Return a tree for the comparison which is the combination of
2283 doing the AND or OR (depending on CODE) of the two operations LCODE
2284 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2285 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2286 if this makes the transformation invalid. */
2288 tree
2292 {
2299 {
2310 }
2313 {
2314 /* Eliminate unordered comparisons, as well as LTGT and ORD
2315 which are not used unless the mode has NaNs. */
2321 }
2323 {
2324 /* Check that the original operation and the optimized ones will trap
2325 under the same condition. */
2336 /* In a short-circuited boolean expression the LHS might be
2337 such that the RHS, if evaluated, will never trap. For
2338 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2339 if neither x nor y is NaN. (This is a mixed blessing: for
2340 example, the expression above will never trap, hence
2341 optimizing it to x < y would be invalid). */
2346 /* If the comparison was short-circuited, and only the RHS
2347 trapped, we may now generate a spurious trap. */
2352 /* If we changed the conditions that cause a trap, we lose. */
2355 }
2361 else
2364 }
2366 /* Return nonzero if CODE is a tree code that represents a truth value. */
2368 static int
2370 {
2375 }
2376 \f
2377 /* Return nonzero if two operands (typically of the same tree node)
2378 are necessarily equal. If either argument has side-effects this
2379 function returns zero. FLAGS modifies behavior as follows:
2381 If OEP_ONLY_CONST is set, only return nonzero for constants.
2382 This function tests whether the operands are indistinguishable;
2383 it does not test whether they are equal using C's == operation.
2384 The distinction is important for IEEE floating point, because
2385 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2386 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2388 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2389 even though it may hold multiple values during a function.
2390 This is because a GCC tree node guarantees that nothing else is
2391 executed between the evaluation of its "operands" (which may often
2392 be evaluated in arbitrary order). Hence if the operands themselves
2393 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2394 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2395 unset means assuming isochronic (or instantaneous) tree equivalence.
2396 Unless comparing arbitrary expression trees, such as from different
2397 statements, this flag can usually be left unset.
2399 If OEP_PURE_SAME is set, then pure functions with identical arguments
2400 are considered the same. It is used when the caller has other ways
2401 to ensure that global memory is unchanged in between. */
2403 int
2405 {
2406 /* If either is ERROR_MARK, they aren't equal. */
2410 /* If both types don't have the same signedness, then we can't consider
2411 them equal. We must check this before the STRIP_NOPS calls
2412 because they may change the signedness of the arguments. */
2420 /* This is needed for conversions and for COMPONENT_REF.
2421 Might as well play it safe and always test this. */
2427 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2428 We don't care about side effects in that case because the SAVE_EXPR
2429 takes care of that for us. In all other cases, two expressions are
2430 equal if they have no side effects. If we have two identical
2431 expressions with side effects that should be treated the same due
2432 to the only side effects being identical SAVE_EXPR's, that will
2433 be detected in the recursive calls below. */
2439 /* Next handle constant cases, those for which we can return 1 even
2440 if ONLY_CONST is set. */
2443 {
2456 {
2466 {
2468 flags))
2472 }
2475 }
2479 flags)
2481 flags));
2494 }
2499 /* Define macros to test an operand from arg0 and arg1 for equality and a
2500 variant that allows null and views null as being different from any
2501 non-null value. In the latter case, if either is null, the both
2502 must be; otherwise, do the normal comparison. */
2503 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2504 TREE_OPERAND (arg1, N), flags)
2506 #define OP_SAME_WITH_NULL(N) \
2507 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2508 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2511 {
2513 /* Two conversions are equal only if signedness and modes match. */
2515 {
2528 }
2538 /* For commutative ops, allow the other order. */
2546 /* If either of the pointer (or reference) expressions we are
2547 dereferencing contain a side effect, these cannot be equal. */
2553 {
2563 /* Operands 2 and 3 may be null. */
2570 /* Handle operand 2 the same as for ARRAY_REF. */
2578 }
2582 {
2597 /* Otherwise take into account this is a commutative operation. */
2604 /* If the CALL_EXPRs call different functions, then they
2605 clearly can not be equal. */
2609 {
2613 else
2617 }
2619 /* Now see if all the arguments are the same. operand_equal_p
2620 does not handle TREE_LIST, so we walk the operands here
2621 feeding them to operand_equal_p. */
2625 {
2627 flags))
2632 }
2634 /* If we get here and both argument lists are exhausted
2635 then the CALL_EXPRs are equal. */
2640 }
2643 /* Consider __builtin_sqrt equal to sqrt. */
2651 }
2653 #undef OP_SAME
2654 #undef OP_SAME_WITH_NULL
2655 }
2656 \f
2657 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2658 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2660 When in doubt, return 0. */
2662 static int
2664 {
2676 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2677 and see if the inner values are the same. This removes any
2678 signedness comparison, which doesn't matter here. */
2685 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2686 actual comparison operand, ARG0.
2688 First throw away any conversions to wider types
2689 already present in the operands. */
2698 {
2701 /* Make sure shorter operand is extended the right way
2702 to match the longer operand. */
2708 }
2711 }
2712 \f
2713 /* See if ARG is an expression that is either a comparison or is performing
2714 arithmetic on comparisons. The comparisons must only be comparing
2715 two different values, which will be stored in *CVAL1 and *CVAL2; if
2716 they are nonzero it means that some operands have already been found.
2717 No variables may be used anywhere else in the expression except in the
2718 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2719 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2721 If this is true, return 1. Otherwise, return zero. */
2723 static int
2725 {
2729 /* We can handle some of the tcc_expression cases here. */
2739 {
2740 /* If we've already found a CVAL1 or CVAL2, this expression is
2741 two complex to handle. */
2747 }
2750 {
2773 /* First see if we can handle the first operand, then the second. For
2774 the second operand, we know *CVAL1 can't be zero. It must be that
2775 one side of the comparison is each of the values; test for the
2776 case where this isn't true by failing if the two operands
2777 are the same. */
2786 ;
2790 ;
2791 else
2795 ;
2799 ;
2800 else
2807 }
2808 }
2809 \f
2810 /* ARG is a tree that is known to contain just arithmetic operations and
2811 comparisons. Evaluate the operations in the tree substituting NEW0 for
2812 any occurrence of OLD0 as an operand of a comparison and likewise for
2813 NEW1 and OLD1. */
2815 static tree
2817 {
2822 /* We can handle some of the tcc_expression cases here. */
2830 {
2845 {
2862 }
2863 /* Fall through - ??? */
2866 {
2870 /* We need to check both for exact equality and tree equality. The
2871 former will be true if the operand has a side-effect. In that
2872 case, we know the operand occurred exactly once. */
2885 }
2889 }
2890 }
2891 \f
2892 /* Return a tree for the case when the result of an expression is RESULT
2893 converted to TYPE and OMITTED was previously an operand of the expression
2894 but is now not needed (e.g., we folded OMITTED * 0).
2896 If OMITTED has side effects, we must evaluate it. Otherwise, just do
2897 the conversion of RESULT to TYPE. */
2899 tree
2901 {
2908 }
2910 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
2912 static tree
2914 {
2921 }
2923 /* Return a tree for the case when the result of an expression is RESULT
2924 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
2925 of the expression but are now not needed.
2927 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
2928 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
2929 evaluated before OMITTED2. Otherwise, if neither has side effects,
2930 just do the conversion of RESULT to TYPE. */
2932 tree
2934 {
2943 }
2945 \f
2946 /* Return a simplified tree node for the truth-negation of ARG. This
2947 never alters ARG itself. We assume that ARG is an operation that
2948 returns a truth value (0 or 1).
2950 FIXME: one would think we would fold the result, but it causes
2951 problems with the dominator optimizer. */
2952 tree
2954 {
2961 /* If this is a comparison, we can simply invert it, except for
2962 floating-point non-equality comparisons, in which case we just
2963 enclose a TRUTH_NOT_EXPR around what we have. */
2966 {
2969 && flag_trapping_math
2973 else
2974 {
2979 else
2982 }
2983 }
2986 {
3001 /* Here we can invert either operand. We invert the first operand
3002 unless the second operand is a TRUTH_NOT_EXPR in which case our
3003 result is the XOR of the first operand with the inside of the
3004 negation of the second operand. */
3009 else
3063 }
3066 }
3068 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3069 operands are another bit-wise operation with a common input. If so,
3070 distribute the bit operations to save an operation and possibly two if
3071 constants are involved. For example, convert
3072 (A | B) & (A | C) into A | (B & C)
3073 Further simplification will occur if B and C are constants.
3075 If this optimization cannot be done, 0 will be returned. */
3077 static tree
3079 {
3080 tree common;
3090 {
3094 }
3096 {
3100 }
3102 {
3106 }
3108 {
3112 }
3113 else
3118 }
3120 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3121 with code CODE. This optimization is unsafe. */
3122 static tree
3124 {
3128 /* (A / C) +- (B / C) -> (A +- B) / C. */
3138 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3143 {
3155 }
3158 }
3159 \f
3160 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3161 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3163 static tree
3166 {
3167 tree result;
3170 {
3177 }
3185 }
3187 /* Optimize a bit-field compare.
3189 There are two cases: First is a compare against a constant and the
3190 second is a comparison of two items where the fields are at the same
3191 bit position relative to the start of a chunk (byte, halfword, word)
3192 large enough to contain it. In these cases we can avoid the shift
3193 implicit in bitfield extractions.
3195 For constants, we emit a compare of the shifted constant with the
3196 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3197 compared. For two fields at the same position, we do the ANDs with the
3198 similar mask and compare the result of the ANDs.
3200 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3201 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3202 are the left and right operands of the comparison, respectively.
3204 If the optimization described above can be done, we return the resulting
3205 tree. Otherwise we return zero. */
3207 static tree
3210 {
3219 tree mask;
3220 tree offset;
3222 /* Get all the information about the extractions being done. If the bit size
3223 if the same as the size of the underlying object, we aren't doing an
3224 extraction at all and so can do nothing. We also don't want to
3225 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3226 then will no longer be able to replace it. */
3234 {
3235 /* If this is not a constant, we can only do something if bit positions,
3236 sizes, and signedness are the same. */
3244 }
3246 /* See if we can find a mode to refer to this field. We should be able to,
3247 but fail if we can't. */
3256 /* Set signed and unsigned types of the precision of this mode for the
3257 shifts below. */
3261 /* Compute the bit position and size for the new reference and our offset
3262 within it. If the new reference is the same size as the original, we
3263 won't optimize anything, so return zero. */
3273 /* Make the mask to be used against the extracted field. */
3282 /* If not comparing with constant, just rework the comparison
3283 and return. */
3288 mask),
3292 mask));
3294 /* Otherwise, we are handling the constant case. See if the constant is too
3295 big for the field. Warn and return a tree of for 0 (false) if so. We do
3296 this not only for its own sake, but to avoid having to test for this
3297 error case below. If we didn't, we might generate wrong code.
3299 For unsigned fields, the constant shifted right by the field length should
3300 be all zero. For signed fields, the high-order bits should agree with
3301 the sign bit. */
3304 {
3308 {
3312 }
3313 }
3314 else
3315 {
3319 {
3323 }
3324 }
3326 /* Single-bit compares should always be against zero. */
3328 {
3331 }
3333 /* Make a new bitfield reference, shift the constant over the
3334 appropriate number of bits and mask it with the computed mask
3335 (in case this was a signed field). If we changed it, make a new one. */
3338 {
3341 }
3351 rhs);
3352 }
3353 \f
3354 /* Subroutine for fold_truthop: decode a field reference.
3356 If EXP is a comparison reference, we return the innermost reference.
3358 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3359 set to the starting bit number.
3361 If the innermost field can be completely contained in a mode-sized
3362 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3364 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3365 otherwise it is not changed.
3367 *PUNSIGNEDP is set to the signedness of the field.
3369 *PMASK is set to the mask used. This is either contained in a
3370 BIT_AND_EXPR or derived from the width of the field.
3372 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3374 Return 0 if this is not a component reference or is one that we can't
3375 do anything with. */
3377 static tree
3382 {
3386 tree unsigned_type;
3389 /* All the optimizations using this function assume integer fields.
3390 There are problems with FP fields since the type_for_size call
3391 below can fail for, e.g., XFmode. */
3395 /* We are interested in the bare arrangement of bits, so strip everything
3396 that doesn't affect the machine mode. However, record the type of the
3397 outermost expression if it may matter below. */
3405 {
3411 }
3420 /* If the number of bits in the reference is the same as the bitsize of
3421 the outer type, then the outer type gives the signedness. Otherwise
3422 (in case of a small bitfield) the signedness is unchanged. */
3426 /* Compute the mask to access the bitfield. */
3436 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3444 }
3446 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3447 bit positions. */
3449 static int
3451 {
3454 tree tmask;
3459 return
3466 }
3468 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3469 represents the sign bit of EXP's type. If EXP represents a sign
3470 or zero extension, also test VAL against the unextended type.
3471 The return value is the (sub)expression whose sign bit is VAL,
3472 or NULL_TREE otherwise. */
3474 static tree
3476 {
3480 tree t;
3482 /* Tree EXP must have an integral type. */
3487 /* Tree VAL must be an integer constant. */
3494 {
3501 }
3502 else
3503 {
3510 }
3512 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3513 treat VAL as if it were unsigned. */
3518 /* Handle extension from a narrower type. */
3524 }
3526 /* Subroutine for fold_truthop: determine if an operand is simple enough
3527 to be evaluated unconditionally. */
3529 static int
3531 {
3532 /* Strip any conversions that don't change the machine mode. */
3541 /* Don't regard global variables as simple. They may be
3542 allocated in ways unknown to the compiler (shared memory,
3543 #pragma weak, etc). */
3546 /* Loading a static variable is unduly expensive, but global
3547 registers aren't expensive. */
3549 }
3550 \f
3551 /* The following functions are subroutines to fold_range_test and allow it to
3552 try to change a logical combination of comparisons into a range test.
3554 For example, both
3555 X == 2 || X == 3 || X == 4 || X == 5
3556 and
3557 X >= 2 && X <= 5
3558 are converted to
3559 (unsigned) (X - 2) <= 3
3561 We describe each set of comparisons as being either inside or outside
3562 a range, using a variable named like IN_P, and then describe the
3563 range with a lower and upper bound. If one of the bounds is omitted,
3564 it represents either the highest or lowest value of the type.
3566 In the comments below, we represent a range by two numbers in brackets
3567 preceded by a "+" to designate being inside that range, or a "-" to
3568 designate being outside that range, so the condition can be inverted by
3569 flipping the prefix. An omitted bound is represented by a "-". For
3570 example, "- [-, 10]" means being outside the range starting at the lowest
3571 possible value and ending at 10, in other words, being greater than 10.
3572 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3573 always false.
3575 We set up things so that the missing bounds are handled in a consistent
3576 manner so neither a missing bound nor "true" and "false" need to be
3577 handled using a special case. */
3579 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3580 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3581 and UPPER1_P are nonzero if the respective argument is an upper bound
3582 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3583 must be specified for a comparison. ARG1 will be converted to ARG0's
3584 type if both are specified. */
3586 static tree
3589 {
3590 tree tem;
3594 /* If neither arg represents infinity, do the normal operation.
3595 Else, if not a comparison, return infinity. Else handle the special
3596 comparison rules. Note that most of the cases below won't occur, but
3597 are handled for consistency. */
3600 {
3605 }
3610 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3611 for neither. In real maths, we cannot assume open ended ranges are
3612 the same. But, this is computer arithmetic, where numbers are finite.
3613 We can therefore make the transformation of any unbounded range with
3614 the value Z, Z being greater than any representable number. This permits
3615 us to treat unbounded ranges as equal. */
3619 {
3640 }
3643 }
3644 \f
3645 /* Given EXP, a logical expression, set the range it is testing into
3646 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
3647 actually being tested. *PLOW and *PHIGH will be made of the same type
3648 as the returned expression. If EXP is not a comparison, we will most
3649 likely not be returning a useful value and range. */
3651 static tree
3653 {
3660 /* Start with simply saying "EXP != 0" and then look at the code of EXP
3661 and see if we can refine the range. Some of the cases below may not
3662 happen, but it doesn't seem worth worrying about this. We "continue"
3663 the outer loop when we've changed something; otherwise we "break"
3664 the switch, which will "break" the while. */
3670 {
3675 {
3687 }
3690 {
3697 /* We can only do something if the range is testing for zero
3698 and if the second operand is an integer constant. Note that
3699 saying something is "in" the range we make is done by
3700 complementing IN_P since it will set in the initial case of
3701 being not equal to zero; "out" is leaving it alone. */
3708 {
3729 }
3731 /* If this is an unsigned comparison, we also know that EXP is
3732 greater than or equal to zero. We base the range tests we make
3733 on that fact, so we record it here so we can parse existing
3734 range tests. We test arg0_type since often the return type
3735 of, e.g. EQ_EXPR, is boolean. */
3737 {
3741 NULL_TREE))
3746 /* If the high bound is missing, but we have a nonzero low
3747 bound, reverse the range so it goes from zero to the low bound
3748 minus 1. */
3750 {
3755 }
3756 }
3762 /* (-x) IN [a,b] -> x in [-b, -a] */
3774 /* ~ X -> -X - 1 */
3783 /* If EXP is signed, any overflow in the computation is undefined,
3784 so we don't worry about it so long as our computations on
3785 the bounds don't overflow. For unsigned, overflow is defined
3786 and this is exactly the right thing. */
3795 /* Check for an unsigned range which has wrapped around the maximum
3796 value thus making n_high < n_low, and normalize it. */
3798 {
3804 /* If the range is of the form +/- [ x+1, x ], we won't
3805 be able to normalize it. But then, it represents the
3806 whole range or the empty set, so make it
3807 +/- [ -, - ]. */
3811 else
3813 }
3814 else
3838 /* If we're converting arg0 from an unsigned type, to exp,
3839 a signed type, we will be doing the comparison as unsigned.
3840 The tests above have already verified that LOW and HIGH
3841 are both positive.
3843 So we have to ensure that we will handle large unsigned
3844 values the same way that the current signed bounds treat
3845 negative values. */
3848 {
3849 tree high_positive;
3853 /* A range without an upper bound is, naturally, unbounded.
3854 Since convert would have cropped a very large value, use
3855 the max value for the destination type. */
3856 high_positive
3863 high_positive),
3865 integer_one_node));
3867 /* If the low bound is specified, "and" the range with the
3868 range for which the original unsigned value will be
3869 positive. */
3871 {
3875 integer_zero_node),
3876 high_positive))
3880 }
3881 else
3882 {
3883 /* Otherwise, "or" the range with the range of the input
3884 that will be interpreted as negative. */
3888 integer_zero_node),
3889 high_positive))
3893 }
3894 }
3902 }
3905 }
3907 /* If EXP is a constant, we can evaluate whether this is true or false. */
3909 {
3916 }
3920 }
3921 \f
3922 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
3923 type, TYPE, return an expression to test if EXP is in (or out of, depending
3924 on IN_P) the range. Return 0 if the test couldn't be created. */
3926 static tree
3928 {
3930 tree value;
3933 {
3939 }
3957 {
3959 {
3963 }
3965 }
3967 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
3969 {
3971 HOST_WIDE_INT hi;
3976 {
3979 }
3980 else
3981 {
3984 }
3987 {
3989 {
3992 }
3995 }
3996 }
4000 {
4003 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4004 for the type in question, as we rely on this here. */
4006 {
4017 {
4023 }
4027 }
4028 }
4034 value);
4037 }
4038 \f
4039 /* Given two ranges, see if we can merge them into one. Return 1 if we
4040 can, 0 if we can't. Set the output range into the specified parameters. */
4042 static int
4045 {
4049 tree tem;
4059 /* Make range 0 be the range that starts first, or ends last if they
4060 start at the same value. Swap them if it isn't. */
4063 || (lowequal
4066 {
4070 }
4072 /* Now flag two cases, whether the ranges are disjoint or whether the
4073 second range is totally subsumed in the first. Note that the tests
4074 below are simplified by the ones above. */
4080 /* We now have four cases, depending on whether we are including or
4081 excluding the two ranges. */
4083 {
4084 /* If they don't overlap, the result is false. If the second range
4085 is a subset it is the result. Otherwise, the range is from the start
4086 of the second to the end of the first. */
4091 else
4093 }
4096 {
4097 /* If they don't overlap, the result is the first range. If they are
4098 equal, the result is false. If the second range is a subset of the
4099 first, and the ranges begin at the same place, we go from just after
4100 the end of the first range to the end of the second. If the second
4101 range is not a subset of the first, or if it is a subset and both
4102 ranges end at the same place, the range starts at the start of the
4103 first range and ends just before the second range.
4104 Otherwise, we can't describe this as a single range. */
4110 {
4114 }
4116 {
4120 }
4121 else
4123 }
4126 {
4127 /* If they don't overlap, the result is the second range. If the second
4128 is a subset of the first, the result is false. Otherwise,
4129 the range starts just after the first range and ends at the
4130 end of the second. */
4135 else
4136 {
4140 }
4141 }
4143 else
4144 {
4145 /* The case where we are excluding both ranges. Here the complex case
4146 is if they don't overlap. In that case, the only time we have a
4147 range is if they are adjacent. If the second is a subset of the
4148 first, the result is the first. Otherwise, the range to exclude
4149 starts at the beginning of the first range and ends at the end of the
4150 second. */
4152 {
4159 else
4160 {
4161 /* Canonicalize - [min, x] into - [-, x]. */
4164 {
4169 /* FALLTHROUGH */
4183 }
4185 /* Canonicalize - [x, max] into - [x, -]. */
4188 {
4193 /* FALLTHROUGH */
4209 }
4211 /* The ranges might be also adjacent between the maximum and
4212 minimum values of the given type. For
4213 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4214 return + [x + 1, y - 1]. */
4216 {
4225 }
4226 else
4228 }
4229 }
4232 else
4234 }
4238 }
4239 \f
4241 /* Subroutine of fold, looking inside expressions of the form
4242 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4243 of the COND_EXPR. This function is being used also to optimize
4244 A op B ? C : A, by reversing the comparison first.
4246 Return a folded expression whose code is not a COND_EXPR
4247 anymore, or NULL_TREE if no folding opportunity is found. */
4249 static tree
4251 {
4256 tree tem;
4261 /* If we have A op 0 ? A : -A, consider applying the following
4262 transformations:
4264 A == 0? A : -A same as -A
4265 A != 0? A : -A same as A
4266 A >= 0? A : -A same as abs (A)
4267 A > 0? A : -A same as abs (A)
4268 A <= 0? A : -A same as -abs (A)
4269 A < 0? A : -A same as -abs (A)
4271 None of these transformations work for modes with signed
4272 zeros. If A is +/-0, the first two transformations will
4273 change the sign of the result (from +0 to -0, or vice
4274 versa). The last four will fix the sign of the result,
4275 even though the original expressions could be positive or
4276 negative, depending on the sign of A.
4278 Note that all these transformations are correct if A is
4279 NaN, since the two alternatives (A and -A) are also NaNs. */
4285 /* In the case that A is of the form X-Y, '-A' (arg2) may
4286 have already been folded to Y-X, check for that. */
4294 {
4306 /* Fall through. */
4328 }
4330 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4331 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4332 both transformations are correct when A is NaN: A != 0
4333 is then true, and A == 0 is false. */
4336 {
4341 }
4343 /* Try some transformations of A op B ? A : B.
4345 A == B? A : B same as B
4346 A != B? A : B same as A
4347 A >= B? A : B same as max (A, B)
4348 A > B? A : B same as max (B, A)
4349 A <= B? A : B same as min (A, B)
4350 A < B? A : B same as min (B, A)
4352 As above, these transformations don't work in the presence
4353 of signed zeros. For example, if A and B are zeros of
4354 opposite sign, the first two transformations will change
4355 the sign of the result. In the last four, the original
4356 expressions give different results for (A=+0, B=-0) and
4357 (A=-0, B=+0), but the transformed expressions do not.
4359 The first two transformations are correct if either A or B
4360 is a NaN. In the first transformation, the condition will
4361 be false, and B will indeed be chosen. In the case of the
4362 second transformation, the condition A != B will be true,
4363 and A will be chosen.
4365 The conversions to max() and min() are not correct if B is
4366 a number and A is not. The conditions in the original
4367 expressions will be false, so all four give B. The min()
4368 and max() versions would give a NaN instead. */
4370 /* Avoid these transformations if the COND_EXPR may be used
4371 as an lvalue in the C++ front-end. PR c++/19199. */
4372 && (in_gimple_form
4376 {
4381 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4383 {
4387 }
4390 {
4399 /* In C++ a ?: expression can be an lvalue, so put the
4400 operand which will be used if they are equal first
4401 so that we can convert this back to the
4402 corresponding COND_EXPR. */
4404 {
4411 }
4418 {
4425 }
4438 }
4439 }
4441 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4442 we might still be able to simplify this. For example,
4443 if C1 is one less or one more than C2, this might have started
4444 out as a MIN or MAX and been transformed by this function.
4445 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4451 {
4453 /* We can replace A with C1 in this case. */
4458 /* If C1 is C2 + 1, this is min(A, C2). */
4460 OEP_ONLY_CONST)
4464 OEP_ONLY_CONST))
4470 /* If C1 is C2 - 1, this is min(A, C2). */
4472 OEP_ONLY_CONST)
4476 OEP_ONLY_CONST))
4482 /* If C1 is C2 - 1, this is max(A, C2). */
4484 OEP_ONLY_CONST)
4488 OEP_ONLY_CONST))
4494 /* If C1 is C2 + 1, this is max(A, C2). */
4496 OEP_ONLY_CONST)
4500 OEP_ONLY_CONST))
4508 }
4511 }
4514 \f
4515 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4516 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4517 #endif
4519 /* EXP is some logical combination of boolean tests. See if we can
4520 merge it into some range test. Return the new tree if so. */
4522 static tree
4524 {
4531 tree tem;
4533 /* If this is an OR operation, invert both sides; we will invert
4534 again at the end. */
4538 /* If both expressions are the same, if we can merge the ranges, and we
4539 can build the range test, return it or it inverted. If one of the
4540 ranges is always true or always false, consider it to be the same
4541 expression as the other. */
4551 /* On machines where the branch cost is expensive, if this is a
4552 short-circuited branch and the underlying object on both sides
4553 is the same, make a non-short-circuit operation. */
4559 {
4560 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4561 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4562 which cases we can't do this. */
4570 {
4582 }
4583 }
4586 }
4587 \f
4588 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
4589 bit value. Arrange things so the extra bits will be set to zero if and
4590 only if C is signed-extended to its full width. If MASK is nonzero,
4591 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4593 static tree
4595 {
4598 tree temp;
4603 /* We work by getting just the sign bit into the low-order bit, then
4604 into the high-order bit, then sign-extend. We then XOR that value
4605 with C. */
4609 /* We must use a signed type in order to get an arithmetic right shift.
4610 However, we must also avoid introducing accidental overflows, so that
4611 a subsequent call to integer_zerop will work. Hence we must
4612 do the type conversion here. At this point, the constant is either
4613 zero or one, and the conversion to a signed type can never overflow.
4614 We could get an overflow if this conversion is done anywhere else. */
4623 /* If necessary, convert the type back to match the type of C. */
4628 }
4629 \f
4630 /* Find ways of folding logical expressions of LHS and RHS:
4631 Try to merge two comparisons to the same innermost item.
4632 Look for range tests like "ch >= '0' && ch <= '9'".
4633 Look for combinations of simple terms on machines with expensive branches
4634 and evaluate the RHS unconditionally.
4636 For example, if we have p->a == 2 && p->b == 4 and we can make an
4637 object large enough to span both A and B, we can do this with a comparison
4638 against the object ANDed with the a mask.
4640 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
4641 operations to do this with one comparison.
4643 We check for both normal comparisons and the BIT_AND_EXPRs made this by
4644 function and the one above.
4646 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
4647 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
4649 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
4650 two operands.
4652 We return the simplified tree or 0 if no optimization is possible. */
4654 static tree
4656 {
4657 /* If this is the "or" of two comparisons, we can do something if
4658 the comparisons are NE_EXPR. If this is the "and", we can do something
4659 if the comparisons are EQ_EXPR. I.e.,
4660 (a->b == 2 && a->c == 4) can become (a->new == NEW).
4662 WANTED_CODE is this operation code. For single bit fields, we can
4663 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
4664 comparison for one-bit fields. */
4684 /* Start by getting the comparison codes. Fail if anything is volatile.
4685 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
4686 it were surrounded with a NE_EXPR. */
4695 {
4699 }
4702 {
4706 }
4717 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
4720 {
4721 tree result;
4724 {
4729 }
4732 {
4738 }
4739 }
4744 /* If the RHS can be evaluated unconditionally and its operands are
4745 simple, it wins to evaluate the RHS unconditionally on machines
4746 with expensive branches. In this case, this isn't a comparison
4747 that can be merged. Avoid doing this if the RHS is a floating-point
4748 comparison since those can trap. */
4754 {
4755 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
4765 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
4777 }
4779 /* See if the comparisons can be merged. Then get all the parameters for
4780 each side. */
4804 /* It must be true that the inner operation on the lhs of each
4805 comparison must be the same if we are to be able to do anything.
4806 Then see if we have constants. If not, the same must be true for
4807 the rhs's. */
4818 else
4821 /* If either comparison code is not correct for our logical operation,
4822 fail. However, we can convert a one-bit comparison against zero into
4823 the opposite comparison against that bit being set in the field. */
4827 {
4829 {
4830 /* Make the left operand unsigned, since we are only interested
4831 in the value of one bit. Otherwise we are doing the wrong
4832 thing below. */
4835 }
4836 else
4838 }
4840 /* This is analogous to the code for l_const above. */
4842 {
4844 {
4847 }
4848 else
4850 }
4852 /* After this point all optimizations will generate bit-field
4853 references, which we might not want. */
4857 /* See if we can find a mode that contains both fields being compared on
4858 the left. If we can't, fail. Otherwise, update all constants and masks
4859 to be relative to a field of that size. */
4864 volatilep);
4874 {
4877 }
4885 {
4893 {
4897 }
4898 }
4900 {
4908 {
4912 }
4913 }
4915 /* If the right sides are not constant, do the same for it. Also,
4916 disallow this optimization if a size or signedness mismatch occurs
4917 between the left and right sides. */
4919 {
4922 /* Make sure the two fields on the right
4923 correspond to the left without being swapped. */
4931 volatilep);
4941 {
4944 }
4951 /* Make a mask that corresponds to both fields being compared.
4952 Do this for both items being compared. If the operands are the
4953 same size and the bits being compared are in the same position
4954 then we can do this by masking both and comparing the masked
4955 results. */
4959 {
4971 }
4973 /* There is still another way we can do something: If both pairs of
4974 fields being compared are adjacent, we may be able to make a wider
4975 field containing them both.
4977 Note that we still must mask the lhs/rhs expressions. Furthermore,
4978 the mask must be shifted to account for the shift done by
4979 make_bit_field_ref. */
4984 {
4985 tree type;
4997 /* Convert to the smaller type before masking out unwanted bits. */
5000 {
5002 {
5006 }
5008 {
5012 }
5013 }
5022 }
5025 }
5027 /* Handle the case of comparisons with constants. If there is something in
5028 common between the masks, those bits of the constants must be the same.
5029 If not, the condition is always false. Test for this to avoid generating
5030 incorrect code below. */
5035 {
5037 {
5040 }
5041 else
5042 {
5045 }
5046 }
5048 /* Construct the expression we will return. First get the component
5049 reference we will make. Unless the mask is all ones the width of
5050 that field, perform the mask operation. Then compare with the
5051 merged constant. */
5061 }
5062 \f
5063 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5064 constant. */
5066 static tree
5068 {
5072 tree minmax_const;
5074 tree inner;
5084 /* If something does not permit us to optimize, return the original tree. */
5092 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5093 and GT_EXPR, doing the rest with recursive calls using logical
5094 simplifications. */
5096 {
5098 {
5099 /* FIXME: We should be able to invert code without building a
5100 scratch tree node, but doing so would require us to
5101 duplicate a part of invert_truthvalue here. */
5108 }
5111 return
5113 optimize_minmax_comparison
5115 optimize_minmax_comparison
5120 /* MAX (X, 0) == 0 -> X <= 0 */
5124 /* MAX (X, 0) == 5 -> X == 5 */
5128 /* MAX (X, 0) == -1 -> false */
5132 /* MIN (X, 0) == 0 -> X >= 0 */
5136 /* MIN (X, 0) == 5 -> false */
5139 else
5140 /* MIN (X, 0) == -1 -> X == -1 */
5145 /* MAX (X, 0) > 0 -> X > 0
5146 MAX (X, 0) > 5 -> X > 5 */
5150 /* MAX (X, 0) > -1 -> true */
5154 /* MIN (X, 0) > 0 -> false
5155 MIN (X, 0) > 5 -> false */
5158 else
5159 /* MIN (X, 0) > -1 -> X > -1 */
5164 }
5165 }
5166 \f
5167 /* T is an integer expression that is being multiplied, divided, or taken a
5168 modulus (CODE says which and what kind of divide or modulus) by a
5169 constant C. See if we can eliminate that operation by folding it with
5170 other operations already in T. WIDE_TYPE, if non-null, is a type that
5171 should be used for the computation if wider than our type.
5173 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5174 (X * 2) + (Y * 4). We must, however, be assured that either the original
5175 expression would not overflow or that overflow is undefined for the type
5176 in the language in question.
5178 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5179 the machine has a multiply-accumulate insn or that this is part of an
5180 addressing calculation.
5182 If we return a non-null expression, it is an equivalent form of the
5183 original computation, but need not be in the original type. */
5185 static tree
5187 {
5188 /* To avoid exponential search depth, refuse to allow recursion past
5189 three levels. Beyond that (1) it's highly unlikely that we'll find
5190 something interesting and (2) we've probably processed it before
5191 when we built the inner expression. */
5194 tree ret;
5199 depth++;
5201 depth--;
5204 }
5206 static tree
5208 {
5218 /* Don't deal with constants of zero here; they confuse the code below. */
5228 /* Note that we need not handle conditional operations here since fold
5229 already handles those cases. So just do arithmetic here. */
5231 {
5233 /* For a constant, we can always simplify if we are a multiply
5234 or (for divide and modulus) if it is a multiple of our constant. */
5242 /* If op0 is an expression ... */
5247 /* ... and is unsigned, and its type is smaller than ctype,
5248 then we cannot pass through as widening. */
5254 /* ... or this is a truncation (t is narrower than op0),
5255 then we cannot pass through this narrowing. */
5258 /* ... or signedness changes for division or modulus,
5259 then we cannot pass through this conversion. */
5265 /* Pass the constant down and see if we can make a simplification. If
5266 we can, replace this expression with the inner simplification for
5267 possible later conversion to our or some other type. */
5272 code == MULT_EXPR
5278 /* If widening the type changes it from signed to unsigned, then we
5279 must avoid building ABS_EXPR itself as unsigned. */
5281 {
5284 {
5287 }
5289 }
5290 /* FALLTHROUGH */
5297 /* If widening the type changes the signedness, then we can't perform
5298 this optimization as that changes the result. */
5302 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5305 {
5311 }
5315 /* If the second operand is constant, this is a multiplication
5316 or floor division, by a power of two, so we can treat it that
5317 way unless the multiplier or divisor overflows. Signed
5318 left-shift overflow is implementation-defined rather than
5319 undefined in C90, so do not convert signed left shift into
5320 multiplication. */
5323 /* const_binop may not detect overflow correctly,
5324 so check for it explicitly here. */
5329 size_one_node,
5339 /* See if we can eliminate the operation on both sides. If we can, we
5340 can return a new PLUS or MINUS. If we can't, the only remaining
5341 cases where we can do anything are if the second operand is a
5342 constant. */
5347 /* If not multiplication, we can only do this if both operands
5348 are divisible by c. */
5354 /* If this was a subtraction, negate OP1 and set it to be an addition.
5355 This simplifies the logic below. */
5362 /* If either OP1 or C are negative, this optimization is not safe for
5363 some of the division and remainder types while for others we need
5364 to change the code. */
5366 {
5374 }
5376 /* If it's a multiply or a division/modulus operation of a multiple
5377 of our constant, do the operation and verify it doesn't overflow. */
5380 {
5383 /* We allow the constant to overflow with wrapping semantics. */
5387 }
5388 else
5391 /* If we have an unsigned type is not a sizetype, we cannot widen
5392 the operation since it will change the result if the original
5393 computation overflowed. */
5399 /* If we were able to eliminate our operation from the first side,
5400 apply our operation to the second side and reform the PLUS. */
5404 /* The last case is if we are a multiply. In that case, we can
5405 apply the distributive law to commute the multiply and addition
5406 if the multiplication of the constants doesn't overflow. */
5412 op1);
5417 /* We have a special case here if we are doing something like
5418 (C * 8) % 4 since we know that's zero. */
5425 /* ... fall through ... */
5429 /* If we can extract our operation from the LHS, do so and return a
5430 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5431 do something only if the second operand is a constant. */
5443 /* If these are the same operation types, we can associate them
5444 assuming no overflow. */
5451 /* If these operations "cancel" each other, we have the main
5452 optimizations of this pass, which occur when either constant is a
5453 multiple of the other, in which case we replace this with either an
5454 operation or CODE or TCODE.
5456 If we have an unsigned type that is not a sizetype, we cannot do
5457 this since it will change the result if the original computation
5458 overflowed. */
5461 && ! flag_wrapv
5466 {
5477 }
5482 }
5485 }
5486 \f
5487 /* Return a node which has the indicated constant VALUE (either 0 or
5488 1), and is of the indicated TYPE. */
5490 tree
5492 {
5497 else
5499 }
5502 /* Return true if expr looks like an ARRAY_REF and set base and
5503 offset to the appropriate trees. If there is no offset,
5504 offset is set to NULL_TREE. Base will be canonicalized to
5505 something you can get the element type from using
5506 TREE_TYPE (TREE_TYPE (base)). */
5508 static bool
5510 {
5511 /* One canonical form is a PLUS_EXPR with the first
5512 argument being an ADDR_EXPR with a possible NOP_EXPR
5513 attached. */
5515 {
5518 /* Strip NOP_EXPRs here because the C frontends and/or
5519 folders present us (int *)&x.a + 4B possibly. */
5522 {
5526 else
5530 }
5531 }
5532 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5533 which we transform into an ADDR_EXPR with appropriate
5534 offset. For other arguments to the ADDR_EXPR we assume
5535 zero offset and as such do not care about the ADDR_EXPR
5536 type and strip possible nops from it. */
5538 {
5541 {
5544 }
5545 else
5546 {
5547 /* Handle array-to-pointer decay as &a. */
5550 else
5553 }
5555 }
5556 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
5559 {
5563 }
5566 }
5569 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
5570 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
5571 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
5572 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
5573 COND is the first argument to CODE; otherwise (as in the example
5574 given here), it is the second argument. TYPE is the type of the
5575 original expression. Return NULL_TREE if no simplification is
5576 possible. */
5578 static tree
5582 {
5589 /* This transformation is only worthwhile if we don't have to wrap
5590 arg in a SAVE_EXPR, and the operation can be simplified on at least
5591 one of the branches once its pushed inside the COND_EXPR. */
5596 {
5600 /* If this operand throws an expression, then it does not make
5601 sense to try to perform a logical or arithmetic operation
5602 involving it. */
5607 }
5608 else
5609 {
5614 }
5618 {
5622 else
5624 }
5626 {
5630 else
5632 }
5636 }
5638 \f
5639 /* Subroutine of fold() that checks for the addition of +/- 0.0.
5641 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
5642 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
5643 ADDEND is the same as X.
5645 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
5646 and finite. The problematic cases are when X is zero, and its mode
5647 has signed zeros. In the case of rounding towards -infinity,
5648 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
5649 modes, X + 0 is not the same as X because -0 + 0 is 0. */
5651 static bool
5653 {
5657 /* Don't allow the fold with -fsignaling-nans. */
5661 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
5665 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
5670 /* The mode has signed zeros, and we have to honor their sign.
5671 In this situation, there is only one case we can return true for.
5672 X - 0 is the same as X unless rounding towards -infinity is
5673 supported. */
5675 }
5677 /* Subroutine of fold() that checks comparisons of built-in math
5678 functions against real constants.
5680 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
5681 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
5682 is the type of the result and ARG0 and ARG1 are the operands of the
5683 comparison. ARG1 must be a TREE_REAL_CST.
5685 The function returns the constant folded tree if a simplification
5686 can be made, and NULL_TREE otherwise. */
5688 static tree
5691 {
5692 REAL_VALUE_TYPE c;
5695 {
5701 {
5702 /* sqrt(x) < y is always false, if y is negative. */
5706 /* sqrt(x) > y is always true, if y is negative and we
5707 don't care about NaNs, i.e. negative values of x. */
5711 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
5714 }
5716 {
5717 REAL_VALUE_TYPE c2;
5723 {
5724 /* sqrt(x) > y is x == +Inf, when y is very large. */
5729 /* sqrt(x) > y is always false, when y is very large
5730 and we don't care about infinities. */
5732 }
5734 /* sqrt(x) > c is the same as x > c*c. */
5737 }
5739 {
5740 REAL_VALUE_TYPE c2;
5746 {
5747 /* sqrt(x) < y is always true, when y is a very large
5748 value and we don't care about NaNs or Infinities. */
5752 /* sqrt(x) < y is x != +Inf when y is very large and we
5753 don't care about NaNs. */
5758 /* sqrt(x) < y is x >= 0 when y is very large and we
5759 don't care about Infinities. */
5764 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
5773 dconst0)),
5776 c2)));
5777 }
5779 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
5784 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
5787 {
5792 dconst0)),
5795 c2)));
5796 }
5797 }
5798 }
5801 }
5803 /* Subroutine of fold() that optimizes comparisons against Infinities,
5804 either +Inf or -Inf.
5806 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
5807 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
5808 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
5810 The function returns the constant folded tree if a simplification
5811 can be made, and NULL_TREE otherwise. */
5813 static tree
5815 {
5817 REAL_VALUE_TYPE max;
5818 tree temp;
5823 /* For negative infinity swap the sense of the comparison. */
5829 {
5831 /* x > +Inf is always false, if with ignore sNANs. */
5837 /* x <= +Inf is always true, if we don't case about NaNs. */
5841 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
5844 {
5847 }
5852 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
5858 /* x < +Inf is always equal to x <= DBL_MAX. */
5864 /* x != +Inf is always equal to !(x > DBL_MAX). */
5870 /* The transformation below creates non-gimple code and thus is
5871 not appropriate if we are in gimple form. */
5881 }
5884 }
5886 /* Subroutine of fold() that optimizes comparisons of a division by
5887 a nonzero integer constant against an integer constant, i.e.
5888 X/C1 op C2.
5890 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
5891 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
5892 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
5894 The function returns the constant folded tree if a simplification
5895 can be made, and NULL_TREE otherwise. */
5897 static tree
5899 {
5904 HOST_WIDE_INT hpart;
5907 /* We have to do this the hard way to detect unsigned overflow.
5908 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
5917 {
5921 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
5930 }
5932 {
5935 {
5953 }
5954 }
5955 else
5956 {
5957 /* A negative divisor reverses the relational operators. */
5962 {
5980 }
5981 }
5984 {
6025 }
6028 }
6031 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6032 equality/inequality test, then return a simplified form of the test
6033 using a sign testing. Otherwise return NULL. TYPE is the desired
6034 result type. */
6036 static tree
6038 tree result_type)
6039 {
6040 /* If this is testing a single bit, we can optimize the test. */
6044 {
6045 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6046 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6050 /* This is only a win if casting to a signed type is cheap,
6051 i.e. when arg00's type is not a partial mode. */
6054 {
6059 }
6060 }
6063 }
6065 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6066 equality/inequality test, then return a simplified form of
6067 the test using shifts and logical operations. Otherwise return
6068 NULL. TYPE is the desired result type. */
6070 tree
6072 tree result_type)
6073 {
6074 /* If this is testing a single bit, we can optimize the test. */
6078 {
6085 tree tem;
6087 /* First, see if we can fold the single bit test into a sign-bit
6088 test. */
6090 result_type);
6094 /* Otherwise we have (A & C) != 0 where C is a single bit,
6095 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6096 Similarly for (A & C) == 0. */
6098 /* If INNER is a right shift of a constant and it plus BITNUM does
6099 not overflow, adjust BITNUM and INNER. */
6106 {
6109 }
6111 /* If we are going to be able to omit the AND below, we must do our
6112 operations as unsigned. If we must use the AND, we have a choice.
6113 Normally unsigned is faster, but for some machines signed is. */
6114 #ifdef LOAD_EXTEND_OP
6117 #else
6119 #endif
6134 /* Put the AND last so it can combine with more things. */
6138 /* Make sure to return the proper type. */
6142 }
6144 }
6146 /* Check whether we are allowed to reorder operands arg0 and arg1,
6147 such that the evaluation of arg1 occurs before arg0. */
6149 static bool
6151 {
6158 }
6160 /* Test whether it is preferable two swap two operands, ARG0 and
6161 ARG1, for example because ARG0 is an integer constant and ARG1
6162 isn't. If REORDER is true, only recommend swapping if we can
6163 evaluate the operands in reverse order. */
6165 bool
6167 {
6203 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6204 for commutative and comparison operators. Ensuring a canonical
6205 form allows the optimizers to find additional redundancies without
6206 having to explicitly check for both orderings. */
6213 }
6215 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6216 ARG0 is extended to a wider type. */
6218 static tree
6220 {
6222 tree arg1_unw;
6231 #ifdef HAVE_canonicalize_funcptr_for_compare
6232 /* Disable this optimization if we're casting a function pointer
6233 type on targets that require function pointer canonicalization. */
6238 #endif
6247 /* If possible, express the comparison in the shorter mode. */
6261 /* If we are comparing with the integer that does not fit into the range
6262 of the shorter type, the result is known. */
6273 {
6300 }
6303 }
6305 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6306 ARG0 just the signedness is changed. */
6308 static tree
6311 {
6323 #ifdef HAVE_canonicalize_funcptr_for_compare
6324 /* Disable this optimization if we're casting a function pointer
6325 type on targets that require function pointer canonicalization. */
6330 #endif
6347 {
6354 }
6355 else
6359 }
6361 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6362 step of the array. Reconstructs s and delta in the case of s * delta
6363 being an integer constant (and thus already folded).
6364 ADDR is the address. MULT is the multiplicative expression.
6365 If the function succeeds, the new address expression is returned. Otherwise
6366 NULL_TREE is returned. */
6368 static tree
6370 {
6374 tree itype;
6376 /* Canonicalize op1 into a possibly non-constant delta
6377 and an INTEGER_CST s. */
6379 {
6386 {
6389 }
6391 {
6394 }
6395 else
6397 }
6399 {
6402 }
6403 else
6404 {
6405 /* Simulate we are delta * 1. */
6408 }
6411 {
6413 {
6423 {
6426 }
6427 else
6428 {
6429 /* Try if delta is a multiple of step. */
6434 }
6437 }
6441 }
6443 /* We found the suitable array reference. So copy everything up to it,
6444 and replace the index. */
6451 {
6455 }
6463 }
6466 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6467 means A >= Y && A != MAX, but in this case we know that
6468 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6470 static tree
6472 {
6479 else
6488 {
6491 }
6493 {
6496 }
6497 else
6508 }
6510 /* Fold a unary expression of code CODE and type TYPE with operand
6511 OP0. Return the folded expression if folding is successful.
6512 Otherwise, return NULL_TREE. */
6514 tree
6516 {
6517 tree tem;
6518 tree arg0;
6526 {
6529 {
6530 /* Don't use STRIP_NOPS, because signedness of argument type
6531 matters. */
6533 }
6534 else
6535 {
6536 /* Strip any conversions that don't change the mode. This
6537 is safe for every expression, except for a comparison
6538 expression because its signedness is derived from its
6539 operands.
6541 Note that this is done as an internal manipulation within
6542 the constant folder, in order to find the simplest
6543 representation of the arguments so that their form can be
6544 studied. In any cases, the appropriate type conversions
6545 should be put back in the tree that will get out of the
6546 constant folder. */
6548 }
6549 }
6552 {
6557 {
6567 /* If this was a conversion, and all we did was to move into
6568 inside the COND_EXPR, bring it back out. But leave it if
6569 it is a conversion from integer to integer and the
6570 result precision is no wider than a word since such a
6571 conversion is cheap and may be optimized away by combine,
6572 while it couldn't if it were outside the COND_EXPR. Then return
6573 so we don't get into an infinite recursion loop taking the
6574 conversion out and then back in. */
6586 && (INTEGRAL_TYPE_P
6598 }
6600 {
6602 {
6606 }
6610 integer_one_node),
6612 integer_zero_node));
6613 }
6614 }
6617 {
6628 /* Handle cases of two conversions in a row. */
6631 {
6653 /* In addition to the cases of two conversions in a row
6654 handled below, if we are converting something to its own
6655 type via an object of identical or wider precision, neither
6656 conversion is needed. */
6662 /* Likewise, if the intermediate and final types are either both
6663 float or both integer, we don't need the middle conversion if
6664 it is wider than the final type and doesn't change the signedness
6665 (for integers). Avoid this if the final type is a pointer
6666 since then we sometimes need the inner conversion. Likewise if
6667 the outer has a precision not equal to the size of its mode. */
6676 && ! final_ptr
6680 /* If we have a sign-extension of a zero-extended value, we can
6681 replace that by a single zero-extension. */
6687 /* Two conversions in a row are not needed unless:
6688 - some conversion is floating-point (overstrict for now), or
6689 - some conversion is a vector (overstrict for now), or
6690 - the intermediate type is narrower than both initial and
6691 final, or
6692 - the intermediate type and innermost type differ in signedness,
6693 and the outermost type is wider than the intermediate, or
6694 - the initial type is a pointer type and the precisions of the
6695 intermediate and final types differ, or
6696 - the final type is a pointer type and the precisions of the
6697 initial and intermediate types differ. */
6712 }
6714 /* Handle (T *)&A.B.C for A being of type T and B and C
6715 living at offset zero. This occurs frequently in
6716 C++ upcasting and then accessing the base. */
6720 {
6722 tree offset;
6728 /* If the reference was to a (constant) zero offset, we can use
6729 the address of the base if it has the same base type
6730 as the result type. */
6735 }
6739 /* Detect assigning a bitfield. */
6742 {
6743 /* Don't leave an assignment inside a conversion
6744 unless assigning a bitfield. */
6746 /* First do the assignment, then return converted constant. */
6751 }
6753 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
6754 constants (if x has signed type, the sign bit cannot be set
6755 in c). This folds extension into the BIT_AND_EXPR. */
6760 {
6770 <= HOST_BITS_PER_WIDE_INT
6772 {
6779 #ifdef LOAD_EXTEND_OP
6781 && !flag_syntax_only
6784 {
6788 }
6789 #endif
6790 }
6792 {
6799 }
6800 }
6802 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
6803 T2 being pointers to types of the same size. */
6808 {
6820 }
6833 /* Convert - (~A) to A + 1. */
6844 /* Convert fabs((double)float) into (double)fabsf(float). */
6847 {
6852 targ0));
6853 }
6854 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
6858 /* Strip sign ops from argument. */
6860 {
6864 }
6892 /* Convert ~ (-A) to A - 1. */
6896 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
6903 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
6920 /* The argument to invert_truthvalue must have Boolean type. */
6924 /* Note that the operand of this must be an int
6925 and its values must be 0 or 1.
6926 ("true" is a fixed value perhaps depending on the language,
6927 but we don't handle values other than 1 correctly yet.) */
6929 /* Avoid infinite recursion. */
6969 }
6971 /* Fold a binary expression of code CODE and type TYPE with operands
6972 OP0 and OP1. Return the folded expression if folding is
6973 successful. Otherwise, return NULL_TREE. */
6975 tree
6977 {
6979 tree tem;
6983 /* WINS will be nonzero when the switch is done
6984 if all operands are constant. */
6994 {
6995 tree subop;
6997 /* Strip any conversions that don't change the mode. This is
6998 safe for every expression, except for a comparison expression
6999 because its signedness is derived from its operands. So, in
7000 the latter case, only strip conversions that don't change the
7001 signedness.
7003 Note that this is done as an internal manipulation within the
7004 constant folder, in order to find the simplest representation
7005 of the arguments so that their form can be studied. In any
7006 cases, the appropriate type conversions should be put back in
7007 the tree that will get out of the constant folder. */
7010 else
7015 else
7020 /* Note that TREE_CONSTANT isn't enough:
7021 static var addresses are constant but we can't
7022 do arithmetic on them. */
7024 }
7027 {
7028 tree subop;
7030 /* Strip any conversions that don't change the mode. This is
7031 safe for every expression, except for a comparison expression
7032 because its signedness is derived from its operands. So, in
7033 the latter case, only strip conversions that don't change the
7034 signedness.
7036 Note that this is done as an internal manipulation within the
7037 constant folder, in order to find the simplest representation
7038 of the arguments so that their form can be studied. In any
7039 cases, the appropriate type conversions should be put back in
7040 the tree that will get out of the constant folder. */
7043 else
7048 else
7053 /* Note that TREE_CONSTANT isn't enough:
7054 static var addresses are constant but we can't
7055 do arithmetic on them. */
7057 }
7059 /* If this is a commutative operation, and ARG0 is a constant, move it
7060 to ARG1 to reduce the number of tests below. */
7065 /* Now WINS is set as described above,
7066 ARG0 is the first operand of EXPR,
7067 and ARG1 is the second operand (if it has more than one operand).
7069 First check for cases where an arithmetic operation is applied to a
7070 compound, conditional, or comparison operation. Push the arithmetic
7071 operation inside the compound or conditional to see if any folding
7072 can then be done. Convert comparison to conditional for this purpose.
7073 The also optimizes non-constant cases that used to be done in
7074 expand_expr.
7076 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
7077 one of the operands is a comparison and the other is a comparison, a
7078 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
7079 code below would make the expression more complex. Change it to a
7080 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
7081 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
7093 {
7097 boolean_type_node,
7105 }
7117 {
7121 arg1));
7129 {
7135 }
7138 {
7144 }
7145 }
7148 {
7150 /* A + (-B) -> A - B */
7155 /* (-A) + B -> B - A */
7161 /* Convert ~A + 1 to -A. */
7168 {
7172 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
7173 with a constant, and the two constants have no bits in common,
7174 we should treat this as a BIT_IOR_EXPR since this may produce more
7175 simplifications. */
7183 {
7186 }
7188 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
7189 (plus (plus (mult) (mult)) (foo)) so that we can
7190 take advantage of the factoring cases below. */
7197 {
7203 else
7225 parg1)));
7226 }
7229 {
7233 /* (A * C) + (B * C) -> (A+B) * C.
7234 We are most concerned about the case where C is a constant,
7235 but other combinations show up during loop reduction. Since
7236 it is not difficult, try all four possibilities. */
7253 /* No identical multiplicands; see if we can find a common
7254 power-of-two factor in non-power-of-two multiplies. This
7255 can help in multi-dimensional array access. */
7260 {
7265 /* Move min of absolute values to int11. */
7268 {
7272 }
7275 {
7281 }
7282 }
7290 }
7292 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
7293 of the array. Loop optimizer sometimes produce this type of
7294 expressions. */
7296 {
7300 }
7302 {
7306 }
7307 }
7308 else
7309 {
7310 /* See if ARG1 is zero and X + ARG1 reduces to X. */
7314 /* Likewise if the operands are reversed. */
7318 /* Convert X + -C into X - C. */
7321 {
7327 }
7335 /* Convert x+x into x*2.0. */
7341 /* Convert x*c+x into x*(c+1). */
7347 {
7348 REAL_VALUE_TYPE c;
7354 }
7356 /* Convert x+x*c into x*(c+1). */
7362 {
7363 REAL_VALUE_TYPE c;
7369 }
7371 /* Convert x*c1+x*c2 into x*(c1+c2). */
7381 {
7390 }
7391 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
7395 {
7400 {
7401 tree tree0;
7404 }
7405 }
7406 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
7410 {
7415 {
7416 tree tree0;
7419 }
7420 }
7421 }
7423 bit_rotate:
7424 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
7425 is a rotate of A by C1 bits. */
7426 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
7427 is a rotate of A by B bits. */
7428 {
7437 {
7456 {
7464 TYPE_PRECISION
7469 ? LROTATE_EXPR
7472 }
7474 {
7482 TYPE_PRECISION
7487 ? LROTATE_EXPR
7490 }
7491 }
7492 }
7494 associate:
7495 /* In most languages, can't associate operations on floats through
7496 parentheses. Rather than remember where the parentheses were, we
7497 don't associate floats at all, unless the user has specified
7498 -funsafe-math-optimizations. */
7502 {
7506 /* Split both trees into variables, constants, and literals. Then
7507 associate each group together, the constants with literals,
7508 then the result with variables. This increases the chances of
7509 literals being recombined later and of generating relocatable
7510 expressions for the sum of a constant and literal. */
7515 /* Only do something if we found more than two objects. Otherwise,
7516 nothing has changed and we risk infinite recursion. */
7521 {
7522 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
7531 /* Preserve the MINUS_EXPR if the negative part of the literal is
7532 greater than the positive part. Otherwise, the multiplicative
7533 folding code (i.e extract_muldiv) may be fooled in case
7534 unsigned constants are subtracted, like in the following
7535 example: ((X*2 + 4) - 8U)/2. */
7537 {
7541 {
7545 }
7546 else
7547 {
7551 }
7552 }
7554 {
7559 else
7560 {
7566 }
7567 }
7572 }
7573 }
7575 binary:
7579 {
7580 /* The return value should always have
7581 the same type as the original expression. */
7586 }
7590 /* A - (-B) -> A + B */
7593 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
7601 /* Convert -A - 1 to ~A. */
7607 /* Convert -1 - A to ~A. */
7613 {
7619 /* Fold A - (A & B) into ~B & A. */
7622 {
7627 arg0);
7632 arg0);
7633 }
7635 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
7636 any power of 2 minus 1. */
7641 {
7647 {
7651 }
7652 }
7653 }
7655 /* See if ARG1 is zero and X - ARG1 reduces to X. */
7659 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
7660 ARG0 is zero and X + ARG0 reduces to X, since that would mean
7661 (-ARG1 + ARG0) reduces to -ARG1. */
7665 /* Fold &x - &x. This can happen from &x.foo - &x.
7666 This is unsafe for certain floats even in non-IEEE formats.
7667 In IEEE, it is unsafe because it does wrong for NaNs.
7668 Also note that operand_equal_p is always false if an operand
7669 is volatile. */
7675 /* A - B -> A + (-B) if B is easily negatable. */
7678 /* Avoid this transformation if B is a positive REAL_CST. */
7686 /* Try folding difference of addresses. */
7687 {
7688 HOST_WIDE_INT diff;
7694 }
7696 /* Fold &a[i] - &a[j] to i-j. */
7701 {
7706 {
7714 }
7715 }
7717 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
7718 of the array. Loop optimizer sometimes produce this type of
7719 expressions. */
7721 {
7725 }
7736 {
7737 /* (A * C) - (B * C) -> (A-B) * C. */
7745 /* (A * C1) - (A * C2) -> A * (C1-C2). */
7753 }
7758 /* (-A) * (-B) -> A * B */
7769 {
7774 /* Transform x * -1 into -x. */
7778 /* (a * (1 << b)) is (a << b) */
7794 }
7795 else
7796 {
7797 /* Maybe fold x * 0 to 0. The expressions aren't the same
7798 when x is NaN, since x * 0 is also NaN. Nor are they the
7799 same in modes with signed zeros, since multiplying a
7800 negative value by 0 gives -0, not +0. */
7805 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
7810 /* Transform x * -1.0 into -x. */
7815 /* Convert (C1/X)*C2 into (C1*C2)/X. */
7820 {
7826 }
7828 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
7830 {
7833 {
7836 }
7837 }
7840 {
7844 /* Optimizations of root(...)*root(...). */
7846 {
7851 /* Optimize sqrt(x)*sqrt(x) as x. */
7857 /* Optimize root(x)*root(y) as root(x*y). */
7862 }
7864 /* Optimize expN(x)*expN(y) as expN(x+y). */
7866 {
7873 }
7875 /* Optimizations of pow(...)*pow(...). */
7879 {
7887 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
7889 {
7894 arg01));
7896 }
7898 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
7900 {
7905 arg));
7907 }
7908 }
7910 /* Optimize tan(x)*cos(x) as sin(x). */
7919 {
7925 }
7927 /* Optimize x*pow(x,c) as pow(x,c+1). */
7931 {
7938 {
7940 REAL_VALUE_TYPE c;
7949 }
7950 }
7952 /* Optimize pow(x,c)*x as pow(x,c+1). */
7956 {
7963 {
7965 REAL_VALUE_TYPE c;
7974 }
7975 }
7977 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
7980 {
7984 {
7989 }
7990 }
7991 }
7992 }
7996 bit_ior:
8004 /* ~X | X is -1. */
8007 {
8011 }
8013 /* X | ~X is -1. */
8016 {
8020 }
8026 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
8028 This results in more efficient code for machines without a NAND
8029 instruction. Combine will canonicalize to the first form
8030 which will allow use of NAND instructions provided by the
8031 backend if they exist. */
8034 {
8039 }
8041 /* See if this can be simplified into a rotate first. If that
8042 is unsuccessful continue in the association code. */
8053 /* ~X ^ X is -1. */
8056 {
8060 }
8062 /* X ^ ~X is -1. */
8065 {
8069 }
8071 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
8072 with a constant, and the two constants have no bits in common,
8073 we should treat this as a BIT_IOR_EXPR since this may produce more
8074 simplifications. */
8082 {
8085 }
8087 /* (X | Y) ^ X -> Y & ~ X*/
8090 {
8093 arg1);
8097 }
8099 /* (Y | X) ^ X -> Y & ~ X*/
8102 {
8105 arg1);
8109 }
8111 /* X ^ (X | Y) -> Y & ~ X*/
8114 {
8117 arg0);
8121 }
8123 /* X ^ (Y | X) -> Y & ~ X*/
8126 {
8129 arg0);
8133 }
8135 /* Convert ~X ^ ~Y to X ^ Y. */
8142 /* See if this can be simplified into a rotate first. If that
8143 is unsuccessful continue in the association code. */
8154 /* ~X & X is always zero. */
8159 /* X & ~X is always zero. */
8167 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
8170 {
8171 unsigned int prec
8178 }
8180 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
8182 This results in more efficient code for machines without a NOR
8183 instruction. Combine will canonicalize to the first form
8184 which will allow use of NOR instructions provided by the
8185 backend if they exist. */
8188 {
8193 }
8198 /* Don't touch a floating-point divide by zero unless the mode
8199 of the constant can represent infinity. */
8205 /* (-A) / (-B) -> A / B */
8215 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
8220 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
8225 /* If ARG1 is a constant, we can convert this to a multiply by the
8226 reciprocal. This does not have the same rounding properties,
8227 so only do this if -funsafe-math-optimizations. We can actually
8228 always safely do it if ARG1 is a power of two, but it's hard to
8229 tell if it is or not in a portable manner. */
8231 {
8236 /* Find the reciprocal if optimizing and the result is exact. */
8238 {
8239 REAL_VALUE_TYPE r;
8242 {
8246 }
8247 }
8248 }
8249 /* Convert A/B/C to A/(B*C). */
8256 /* Convert A/(B/C) to (A/B)*C. */
8264 /* Convert C1/(X*C2) into (C1/C2)/X. */
8269 {
8275 }
8278 {
8280 /* Optimize x/expN(y) into x*expN(-y). */
8282 {
8289 }
8291 /* Optimize x/pow(y,z) into x*pow(y,-z). */
8295 {
8304 }
8305 }
8308 {
8312 /* Optimize sin(x)/cos(x) as tan(x). */
8318 {
8324 }
8326 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
8332 {
8336 {
8341 }
8342 }
8344 /* Optimize pow(x,c)/x as pow(x,c-1). */
8348 {
8354 {
8356 REAL_VALUE_TYPE c;
8365 }
8366 }
8367 }
8379 /* X / -1 is -X. */
8386 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
8387 operation, EXACT_DIV_EXPR.
8389 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
8390 At one time others generated faster code, it's not clear if they do
8391 after the last round to changes to the DIV code in expmed.c. */
8406 /* X % 1 is always zero, but be sure to preserve any side
8407 effects in X. */
8411 /* X % 0, return X % 0 unchanged so that we can get the
8412 proper warnings and errors. */
8416 /* 0 % X is always zero, but be sure to preserve any side
8417 effects in X. Place this after checking for X == 0. */
8421 /* X % -1 is zero. */
8428 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
8429 i.e. "X % C" into "X & C2", if X and C are positive. */
8433 {
8435 tree mask;
8440 {
8444 }
8445 else
8446 {
8449 }
8454 }
8456 /* X % -C is the same as X % C. */
8462 && !flag_trapv
8463 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
8468 /* X % -Y is the same as X % Y. */
8489 /* Optimize -1 >> x for arithmetic right shifts. */
8492 /* ... fall through ... */
8495 shift:
8501 /* Since negative shift count is not well-defined,
8502 don't try to compute it in the compiler. */
8506 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
8511 {
8515 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
8516 being well defined. */
8518 {
8523 else
8525 }
8529 }
8531 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
8532 into x & ((unsigned)-1 >> c) for unsigned types. */
8540 {
8543 tree lshift;
8544 tree arg00;
8547 {
8554 }
8555 }
8557 /* Rewrite an LROTATE_EXPR by a constant into an
8558 RROTATE_EXPR by a new constant. */
8560 {
8566 }
8568 /* If we have a rotate of a bit operation with the rotate count and
8569 the second operand of the bit operation both constant,
8570 permute the two operations. */
8582 /* Two consecutive rotates adding up to the width of the mode can
8583 be ignored. */
8614 /* Note that the operands of this must be ints
8615 and their values must be 0 or 1.
8616 ("true" is a fixed value perhaps depending on the language.) */
8617 /* If first arg is constant zero, return it. */
8621 /* If either arg is constant true, drop it. */
8625 /* Preserve sequence points. */
8628 /* If second arg is constant zero, result is zero, but first arg
8629 must be evaluated. */
8632 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
8633 case will be handled here. */
8637 /* !X && X is always false. */
8641 /* X && !X is always false. */
8646 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
8647 means A >= Y && A != MAX, but in this case we know that
8648 A < X <= MAX. */
8652 {
8660 }
8662 truth_andor:
8663 /* We only do these simplifications if we are optimizing. */
8667 /* Check for things like (A || B) && (A || C). We can convert this
8668 to A || (B && C). Note that either operator can be any of the four
8669 truth and/or operations and the transformation will still be
8670 valid. Also note that we only care about order for the
8671 ANDIF and ORIF operators. If B contains side effects, this
8672 might change the truth-value of A. */
8679 {
8699 /* This case if tricky because we must either have commutative
8700 operators or else A10 must not have side-effects. */
8706 a01);
8707 }
8709 /* See if we can build a range comparison. */
8713 /* Check for the possibility of merging component references. If our
8714 lhs is another similar operation, try to merge its rhs with our
8715 rhs. Then try to merge our lhs and rhs. */
8727 /* Note that the operands of this must be ints
8728 and their values must be 0 or true.
8729 ("true" is a fixed value perhaps depending on the language.) */
8730 /* If first arg is constant true, return it. */
8734 /* If either arg is constant zero, drop it. */
8738 /* Preserve sequence points. */
8741 /* If second arg is constant true, result is true, but we must
8742 evaluate first arg. */
8745 /* Likewise for first arg, but note this only occurs here for
8746 TRUTH_OR_EXPR. */
8750 /* !X || X is always true. */
8754 /* X || !X is always true. */
8762 /* If the second arg is constant zero, drop it. */
8765 /* If the second arg is constant true, this is a logical inversion. */
8767 {
8768 /* Only call invert_truthvalue if operand is a truth value. */
8771 else
8774 }
8775 /* Identical arguments cancel to zero. */
8779 /* !X ^ X is always true. */
8784 /* X ^ !X is always true. */
8797 /* If one arg is a real or integer constant, put it last. */
8801 /* bool_var != 0 becomes bool_var. */
8806 /* bool_var == 1 becomes bool_var. */
8811 /* If this is an equality comparison of the address of a non-weak
8812 object against zero, then we know the result. */
8820 /* If this is an equality comparison of the address of two non-weak,
8821 unaliased symbols neither of which are extern (since we do not
8822 have access to attributes for externs), then we know the result. */
8836 {
8837 /* We know that we're looking at the address of two
8838 non-weak, unaliased, static _DECL nodes.
8840 It is both wasteful and incorrect to call operand_equal_p
8841 to compare the two ADDR_EXPR nodes. It is wasteful in that
8842 all we need to do is test pointer equality for the arguments
8843 to the two ADDR_EXPR nodes. It is incorrect to use
8844 operand_equal_p as that function is NOT equivalent to a
8845 C equality test. It can in fact return false for two
8846 objects which would test as equal using the C equality
8847 operator. */
8851 type);
8852 }
8854 /* If this is a comparison of two exprs that look like an
8855 ARRAY_REF of the same object, then we can fold this to a
8856 comparison of the two offsets. */
8858 {
8864 {
8873 {
8876 }
8884 }
8885 }
8887 /* Transform comparisons of the form X +- C CMP X. */
8896 {
8903 else
8906 /* (X - c) > X becomes false. */
8912 /* Likewise (X + c) < X becomes false. */
8918 /* Convert (X - c) <= X to true. */
8925 /* Convert (X + c) >= X to true. */
8933 {
8934 /* Convert X + c > X and X - c < X to true for integers. */
8945 /* Convert X + c <= X and X - c >= X to false for integers. */
8955 }
8956 }
8958 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8966 {
8970 tree lhs;
8980 }
8983 {
8991 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8996 /* (-a) CMP (-b) -> b CMP a */
9003 {
9004 REAL_VALUE_TYPE cst;
9007 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9009 return
9015 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9016 /* a CMP (-0) -> a CMP 0 */
9021 /* x != NaN is always true, other ops are always false. */
9024 {
9027 }
9029 /* Fold comparisons against infinity. */
9031 {
9035 }
9036 }
9038 /* If this is a comparison of a real constant with a PLUS_EXPR
9039 or a MINUS_EXPR of a real constant, we can convert it into a
9040 comparison with a revised real constant as long as no overflow
9041 occurs when unsafe_math_optimizations are enabled. */
9053 /* Likewise, we can simplify a comparison of a real constant with
9054 a MINUS_EXPR whose first operand is also a real constant, i.e.
9055 (c1 - x) < c2 becomes x > c1-c2. */
9066 /* Fold comparisons against built-in math functions. */
9068 && flag_unsafe_math_optimizations
9070 {
9074 {
9078 }
9079 }
9080 }
9082 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
9086 /* This optimization is invalid for ordered comparisons
9087 if CONST+INCR overflows or if foo+incr might overflow.
9088 This optimization is invalid for floating point due to rounding.
9089 For pointer types we assume overflow doesn't happen. */
9093 {
9097 {
9103 }
9104 else
9105 {
9111 }
9114 /* If VAROP is a reference to a bitfield, we must mask
9115 the constant by the width of the field. */
9120 {
9125 /* First check whether the comparison would come out
9126 always the same. If we don't do that we would
9127 change the meaning with the masking. */
9141 }
9144 }
9146 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
9147 This transformation affects the cases which are handled in later
9148 optimizations involving comparisons with non-negative constants. */
9152 {
9154 {
9169 }
9170 }
9172 /* Comparisons with the highest or lowest possible integer of
9173 the specified size will have known values. */
9174 {
9182 {
9183 HOST_WIDE_INT signed_max_hi;
9188 {
9195 {
9199 }
9200 else
9201 {
9205 }
9206 }
9207 else
9208 {
9217 {
9220 }
9221 else
9222 {
9225 }
9226 }
9231 {
9244 /* The GE_EXPR and LT_EXPR cases above are not normally
9245 reached because of previous transformations. */
9249 }
9251 == max_hi
9254 {
9263 }
9265 == min_hi
9268 {
9283 }
9285 == min_hi
9288 {
9297 }
9303 /* signed_type does not work on pointer types. */
9305 {
9306 /* The following case also applies to X < signed_max+1
9307 and X >= signed_max+1 because previous transformations. */
9309 {
9313 return fold
9317 }
9318 }
9319 }
9320 }
9322 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
9323 a MINUS_EXPR of a constant, we can convert it into a comparison with
9324 a revised constant as long as no overflow occurs. */
9336 /* Similarly for a NEGATE_EXPR. */
9345 /* If we have X - Y == 0, we can convert that to X == Y and similarly
9346 for !=. Don't do this for ordered comparisons due to overflow. */
9355 {
9356 /* If we are widening one operand of an integer comparison,
9357 see if the other operand is similarly being widened. Perhaps we
9358 can do the comparison in the narrower type. */
9363 /* Or if we are changing signedness. */
9367 }
9369 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9370 constant, we can simplify it. */
9375 {
9381 }
9383 /* If we are comparing an ABS_EXPR with a constant, we can
9384 convert all the cases into explicit comparisons, but they may
9385 well not be faster than doing the ABS and one comparison.
9386 But ABS (X) <= C is a range comparison, which becomes a subtraction
9387 and a comparison, and is probably faster. */
9400 /* Convert ABS_EXPR<x> >= 0 to true. */
9408 /* Convert ABS_EXPR<x> < 0 to false. */
9414 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
9420 /* If this is an EQ or NE comparison with zero and ARG0 is
9421 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
9422 two operations, but the latter can be done in one less insn
9423 on machines that have only two-operand insns or on which a
9424 constant cannot be the first operand. */
9427 {
9432 return
9438 integer_one_node)),
9439 arg1);
9442 return
9448 integer_one_node)),
9449 arg1);
9450 }
9452 /* If this is an NE or EQ comparison of zero against the result of a
9453 signed MOD operation whose second operand is a power of 2, make
9454 the MOD operation unsigned since it is simpler and equivalent. */
9463 {
9473 }
9475 /* If this is an NE comparison of zero with an AND of one, remove the
9476 comparison since the AND will give the correct value. */
9482 /* If we have (A & C) == C where C is a power of 2, convert this into
9483 (A & C) != 0. Similarly for NE_EXPR. */
9490 integer_zero_node));
9492 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
9493 bit, then fold the expression into A < 0 or A >= 0. */
9498 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
9499 Similarly for NE_EXPR. */
9504 {
9513 }
9515 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
9516 Similarly for NE_EXPR. */
9521 {
9528 }
9530 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
9531 and similarly for >= into !=. */
9547 return
9555 /* Simplify comparison of something with itself. (For IEEE
9556 floating-point, we can only do some of these simplifications.) */
9558 {
9560 {
9575 /* For NE, we can only do this simplification if integer
9576 or we don't honor IEEE floating point NaNs. */
9580 /* ... fall through ... */
9586 }
9587 }
9589 /* If we are comparing an expression that just has comparisons
9590 of two integer values, arithmetic expressions of those comparisons,
9591 and constants, we can simplify it. There are only three cases
9592 to check: the two values can either be equal, the first can be
9593 greater, or the second can be greater. Fold the expression for
9594 those three values. Since each value must be 0 or 1, we have
9595 eight possibilities, each of which corresponds to the constant 0
9596 or 1 or one of the six possible comparisons.
9598 This handles common cases like (a > b) == 0 but also handles
9599 expressions like ((x > y) - (y > x)) > 0, which supposedly
9600 occur in macroized code. */
9603 {
9608 /* Don't handle degenerate cases here; they should already
9609 have been handled anyway. */
9618 {
9622 /* We can't just pass T to eval_subst in case cval1 or cval2
9623 was the same as ARG1. */
9625 tree high_result
9629 arg1);
9630 tree equal_result
9634 arg1);
9635 tree low_result
9639 arg1);
9641 /* All three of these results should be 0 or 1. Confirm they
9642 are. Then use those values to select the proper code
9643 to use. */
9651 {
9652 /* Make a 3-bit mask with the high-order bit being the
9653 value for `>', the next for '=', and the low for '<'. */
9657 {
9659 /* Always false. */
9680 /* Always true. */
9682 }
9686 else
9688 }
9689 }
9690 }
9692 /* If this is a comparison of a field, we may be able to simplify it. */
9697 /* Handle the constant case even without -O
9698 to make sure the warnings are given. */
9700 {
9704 }
9706 /* Fold a comparison of the address of COMPONENT_REFs with the same
9707 type and component to a comparison of the address of the base
9708 object. In short, &x->a OP &y->a to x OP y and
9709 &x->a OP &y.a to x OP &y */
9714 {
9718 {
9724 }
9725 }
9727 /* Optimize comparisons of strlen vs zero to a compare of the
9728 first character of the string vs zero. To wit,
9729 strlen(ptr) == 0 => *ptr == 0
9730 strlen(ptr) != 0 => *ptr != 0
9731 Other cases should reduce to one of these two (or a constant)
9732 due to the return value of strlen being unsigned. */
9736 {
9738 tree arglist;
9746 {
9750 }
9751 }
9753 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9754 into a single range test. */
9762 {
9766 }
9771 {
9774 }
9788 {
9792 }
9794 /* If the first operand is NaN, the result is constant. */
9798 {
9800 ? integer_zero_node
9803 }
9805 /* If the second operand is NaN, the result is constant. */
9809 {
9811 ? integer_zero_node
9814 }
9816 /* Simplify unordered comparison of something with itself. */
9822 && !flag_trapping_math
9826 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9827 {
9838 }
9843 /* When pedantic, a compound expression can be neither an lvalue
9844 nor an integer constant expression. */
9847 /* Don't let (0, 0) be null pointer constant. */
9858 /* An ASSERT_EXPR should never be passed to fold_binary. */
9864 }
9866 /* Callback for walk_tree, looking for LABEL_EXPR.
9867 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
9868 Do not check the sub-tree of GOTO_EXPR. */
9870 static tree
9874 {
9876 {
9881 /* no break */
9884 }
9885 }
9887 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
9888 accessible from outside the sub-tree. Returns NULL_TREE if no
9889 addressable label is found. */
9891 static bool
9893 {
9895 }
9897 /* Fold a ternary expression of code CODE and type TYPE with operands
9898 OP0, OP1, and OP2. Return the folded expression if folding is
9899 successful. Otherwise, return NULL_TREE. */
9901 tree
9903 {
9904 tree tem;
9911 /* Strip any conversions that don't change the mode. This is safe
9912 for every expression, except for a comparison expression because
9913 its signedness is derived from its operands. So, in the latter
9914 case, only strip conversions that don't change the signedness.
9916 Note that this is done as an internal manipulation within the
9917 constant folder, in order to find the simplest representation of
9918 the arguments so that their form can be studied. In any cases,
9919 the appropriate type conversions should be put back in the tree
9920 that will get out of the constant folder. */
9922 {
9925 }
9928 {
9931 }
9934 {
9938 {
9944 }
9948 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
9949 so all simple results must be passed through pedantic_non_lvalue. */
9951 {
9954 /* Only optimize constant conditions when the selected branch
9955 has the same type as the COND_EXPR. This avoids optimizing
9956 away "c ? x : throw", where the throw has a void type.
9957 Avoid throwing away that operand which contains label. */
9964 }
9968 /* If we have A op B ? A : C, we may be able to convert this to a
9969 simpler expression, depending on the operation and the values
9970 of B and C. Signed zeros prevent all of these transformations,
9971 for reasons given above each one.
9973 Also try swapping the arguments and inverting the conditional. */
9978 {
9982 }
9986 op2,
9989 {
9992 {
9996 }
9997 }
9999 /* If the second operand is simpler than the third, swap them
10000 since that produces better jump optimization results. */
10002 {
10003 /* See if this can be inverted. If it can't, possibly because
10004 it was a floating-point inequality comparison, don't do
10005 anything. */
10010 }
10012 /* Convert A ? 1 : 0 to simply A. */
10015 /* If we try to convert OP0 to our type, the
10016 call to fold will try to move the conversion inside
10017 a COND, which will recurse. In that case, the COND_EXPR
10018 is probably the best choice, so leave it alone. */
10022 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
10023 over COND_EXPR in cases such as floating point comparisons. */
10030 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
10038 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
10039 already handled above. */
10044 {
10053 }
10055 /* A & N ? N : 0 is simply A & N if N is a power of two. This
10056 is probably obsolete because the first operand should be a
10057 truth value (that's why we have the two cases above), but let's
10058 leave it in until we can confirm this for all front-ends. */
10069 /* Convert A ? B : 0 into A && B if A and B are truth values. */
10075 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
10079 {
10080 /* Only perform transformation if ARG0 is easily inverted. */
10084 }
10086 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
10090 {
10091 /* Only perform transformation if ARG0 is easily inverted. */
10095 }
10097 /* Convert A ? 1 : B into A || B if A and B are truth values. */
10106 /* Check for a built-in function. */
10110 {
10116 }
10124 {
10133 {
10139 else
10141 }
10142 }
10148 }
10150 /* Perform constant folding and related simplification of EXPR.
10151 The related simplifications include x*1 => x, x*0 => 0, etc.,
10152 and application of the associative law.
10153 NOP_EXPR conversions may be removed freely (as long as we
10154 are careful not to change the type of the overall expression).
10155 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
10156 but we can constant-fold them if they have constant operands. */
10158 #ifdef ENABLE_FOLD_CHECKING
10159 # define fold(x) fold_1 (x)
10161 static
10162 #endif
10163 tree
10165 {
10169 tree tem;
10171 /* Return right away if a constant. */
10176 {
10181 {
10199 }
10200 }
10203 {
10210 }
10212 #ifdef ENABLE_FOLD_CHECKING
10213 #undef fold
10219 /* When --enable-checking=fold, compute a digest of expr before
10220 and after actual fold call to see if fold did not accidentally
10221 change original expr. */
10223 tree
10225 {
10226 tree ret;
10229 htab_t ht;
10248 }
10250 void
10252 {
10255 htab_t ht;
10265 }
10267 static void
10269 {
10271 }
10273 static void
10275 {
10281 recursive_label:
10295 {
10296 /* Allow DECL_ASSEMBLER_NAME to be modified. */
10300 }
10305 {
10306 /* Allow these fields to be modified. */
10313 {
10316 }
10317 }
10325 {
10328 {
10342 }
10346 {
10359 }
10393 {
10396 }
10406 }
10407 }
10409 #endif
10411 /* Fold a unary tree expression with code CODE of type TYPE with an
10412 operand OP0. Return a folded expression if successful. Otherwise,
10413 return a tree expression with code CODE of type TYPE with an
10414 operand OP0. */
10416 tree
10418 {
10419 tree tem;
10420 #ifdef ENABLE_FOLD_CHECKING
10423 htab_t ht;
10430 #endif
10436 #ifdef ENABLE_FOLD_CHECKING
10444 #endif
10446 }
10448 /* Fold a binary tree expression with code CODE of type TYPE with
10449 operands OP0 and OP1. Return a folded expression if successful.
10450 Otherwise, return a tree expression with code CODE of type TYPE
10451 with operands OP0 and OP1. */
10453 tree
10455 {
10456 tree tem;
10457 #ifdef ENABLE_FOLD_CHECKING
10463 htab_t ht;
10475 #endif
10481 #ifdef ENABLE_FOLD_CHECKING
10497 #endif
10499 }
10501 /* Fold a ternary tree expression with code CODE of type TYPE with
10502 operands OP0, OP1, and OP2. Return a folded expression if
10503 successful. Otherwise, return a tree expression with code CODE of
10504 type TYPE with operands OP0, OP1, and OP2. */
10506 tree
10509 #ifdef ENABLE_FOLD_CHECKING
10517 htab_t ht;
10534 #endif
10540 #ifdef ENABLE_FOLD_CHECKING
10564 #endif
10566 }
10568 /* Perform constant folding and related simplification of initializer
10569 expression EXPR. This behaves identically to "fold" but ignores
10570 potential run-time traps and exceptions that fold must preserve. */
10572 tree
10574 {
10579 tree result;
10594 }
10596 /* Determine if first argument is a multiple of second argument. Return 0 if
10597 it is not, or we cannot easily determined it to be.
10599 An example of the sort of thing we care about (at this point; this routine
10600 could surely be made more general, and expanded to do what the *_DIV_EXPR's
10601 fold cases do now) is discovering that
10603 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
10605 is a multiple of
10607 SAVE_EXPR (J * 8)
10609 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
10611 This code also handles discovering that
10613 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
10615 is a multiple of 8 so we don't have to worry about dealing with a
10616 possible remainder.
10618 Note that we *look* inside a SAVE_EXPR only to determine how it was
10619 calculated; it is not safe for fold to do much of anything else with the
10620 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
10621 at run time. For example, the latter example above *cannot* be implemented
10622 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
10623 evaluation time of the original SAVE_EXPR is not necessarily the same at
10624 the time the new expression is evaluated. The only optimization of this
10625 sort that would be valid is changing
10627 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
10629 divided by 8 to
10631 SAVE_EXPR (I) * SAVE_EXPR (J)
10633 (where the same SAVE_EXPR (J) is used in the original and the
10634 transformed version). */
10636 static int
10638 {
10646 {
10648 /* Bitwise and provides a power of two multiple. If the mask is
10649 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
10652 /* FALLTHRU */
10665 {
10669 /* const_binop may not detect overflow correctly,
10670 so check for it explicitly here. */
10676 size_one_node,
10680 }
10684 /* Can't handle conversions from non-integral or wider integral type. */
10690 /* .. fall through ... */
10706 }
10707 }
10709 /* Return true if `t' is known to be non-negative. */
10711 int
10713 {
10718 {
10720 /* We can't return 1 if flag_wrapv is set because
10721 ABS_EXPR<INT_MIN> = INT_MIN. */
10737 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
10738 both unsigned and at least 2 bits shorter than the result. */
10742 {
10747 {
10751 }
10752 }
10757 {
10758 /* x * x for floating point x is always non-negative. */
10763 }
10765 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
10766 both unsigned and their total bits is shorter than the result. */
10770 {
10777 }
10806 {
10811 {
10815 {
10819 }
10820 }
10822 {
10828 }
10829 }
10855 {
10859 /* If the initializer is non-void, then it's a normal expression
10860 that will be assigned to the slot. */
10864 /* Otherwise, the initializer sets the slot in some way. One common
10865 way is an assignment statement at the end of the initializer. */
10867 {
10875 else
10877 }
10883 }
10886 {
10891 {
10892 #define CASE_BUILTIN_F(BUILT_IN_FN) \
10893 case BUILT_IN_FN: case BUILT_IN_FN##F: case BUILT_IN_FN##L:
10894 #define CASE_BUILTIN_I(BUILT_IN_FN) \
10895 case BUILT_IN_FN: case BUILT_IN_FN##L: case BUILT_IN_FN##LL:
10913 /* Always true. */
10917 /* sqrt(-0.0) is -0.0. */
10949 /* True if the 1st argument is nonnegative. */
10953 /* True if the 1st OR 2nd arguments are nonnegative. */
10958 /* True if the 1st AND 2nd arguments are nonnegative. */
10963 /* True if the 2nd argument is nonnegative. */
10968 #undef CASE_BUILTIN_F
10969 #undef CASE_BUILTIN_I
10970 }
10971 }
10973 /* ... fall through ... */
10977 /* Truth values evaluate to 0 or 1, which is nonnegative. */
10979 }
10981 /* We don't know sign of `t', so be conservative and return false. */
10983 }
10985 /* Return true when T is an address and is known to be nonzero.
10986 For floating point we further ensure that T is not denormal.
10987 Similar logic is present in nonzero_address in rtlanal.h. */
10989 bool
10991 {
10994 /* Doing something useful for floating point would need more work. */
10999 {
11004 /* We used to test for !integer_zerop here. This does not work correctly
11005 if TREE_CONSTANT_OVERFLOW (t). */
11011 {
11012 /* With the presence of negative values it is hard
11013 to say something. */
11017 /* One of operands must be positive and the other non-negative. */
11020 }
11025 {
11028 }
11032 {
11038 }
11042 {
11048 /* Weak declarations may link to NULL. */
11052 /* Constants are never weak. */
11057 }
11069 {
11070 /* When both operands are nonzero, then MAX must be too. */
11074 /* MAX where operand 0 is positive is positive. */
11076 }
11077 /* MAX where operand 1 is positive is positive. */
11101 }
11103 }
11105 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
11106 attempt to fold the expression to a constant without modifying TYPE,
11107 OP0 or OP1.
11109 If the expression could be simplified to a constant, then return
11110 the constant. If the expression would not be simplified to a
11111 constant, then return NULL_TREE. */
11113 tree
11115 {
11118 }
11120 /* Given the components of a unary expression CODE, TYPE and OP0,
11121 attempt to fold the expression to a constant without modifying
11122 TYPE or OP0.
11124 If the expression could be simplified to a constant, then return
11125 the constant. If the expression would not be simplified to a
11126 constant, then return NULL_TREE. */
11128 tree
11130 {
11133 }
11135 /* If EXP represents referencing an element in a constant string
11136 (either via pointer arithmetic or array indexing), return the
11137 tree representing the value accessed, otherwise return NULL. */
11139 tree
11141 {
11143 {
11145 tree index;
11146 tree string;
11150 else
11151 {
11155 /* Optimize the special-case of a zero lower bound.
11157 We convert the low_bound to sizetype to avoid some problems
11158 with constant folding. (E.g. suppose the lower bound is 1,
11159 and its mode is QI. Without the conversion,l (ARRAY
11160 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
11161 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
11166 }
11180 }
11182 }
11184 /* Return the tree for neg (ARG0) when ARG0 is known to be either
11185 an integer constant or real constant.
11187 TYPE is the type of the result. */
11189 static tree
11191 {
11195 {
11197 {
11199 HOST_WIDE_INT high;
11209 }
11217 }
11220 }
11222 /* Return the tree for abs (ARG0) when ARG0 is known to be either
11223 an integer constant or real constant.
11225 TYPE is the type of the result. */
11227 tree
11229 {
11233 {
11235 /* If the value is unsigned, then the absolute value is
11236 the same as the ordinary value. */
11239 /* Similarly, if the value is non-negative. */
11242 /* If the value is negative, then the absolute value is
11243 its negation. */
11244 else
11245 {
11247 HOST_WIDE_INT high;
11254 }
11260 else
11266 }
11269 }
11271 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
11272 constant. TYPE is the type of the result. */
11274 static tree
11276 {
11288 }
11290 /* Given CODE, a relational operator, the target type, TYPE and two
11291 constant operands OP0 and OP1, return the result of the
11292 relational operation. If the result is not a compile time
11293 constant, then return NULL_TREE. */
11295 static tree
11297 {
11300 /* From here on, the only cases we handle are when the result is
11301 known to be a constant. */
11304 {
11308 /* Handle the cases where either operand is a NaN. */
11310 {
11312 {
11340 }
11343 }
11346 }
11348 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
11350 To compute GT, swap the arguments and do LT.
11351 To compute GE, do LT and invert the result.
11352 To compute LE, swap the arguments, do LT and invert the result.
11353 To compute NE, do EQ and invert the result.
11355 Therefore, the code below must handle only EQ and LT. */
11358 {
11363 }
11365 /* Note that it is safe to invert for real values here because we
11366 have already handled the one case that it matters. */
11370 {
11373 }
11375 /* Compute a result for LT or EQ if args permit;
11376 Otherwise return T. */
11378 {
11383 else
11385 }
11386 else
11392 }
11394 /* Build an expression for the a clean point containing EXPR with type TYPE.
11395 Don't build a cleanup point expression for EXPR which don't have side
11396 effects. */
11398 tree
11400 {
11401 /* If the expression does not have side effects then we don't have to wrap
11402 it with a cleanup point expression. */
11406 /* If the expression is a return, check to see if the expression inside the
11407 return has no side effects or the right hand side of the modify expression
11408 inside the return. If either don't have side effects set we don't need to
11409 wrap the expression in a cleanup point expression. Note we don't check the
11410 left hand side of the modify because it should always be a return decl. */
11412 {
11419 }
11422 }
11424 /* Build an expression for the address of T. Folds away INDIRECT_REF to
11425 avoid confusing the gimplify process. */
11427 tree
11429 {
11430 /* The size of the object is not relevant when talking about its address. */
11434 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
11437 {
11441 }
11442 else
11443 {
11452 }
11455 }
11457 tree
11459 {
11461 }
11463 /* Given a pointer value OP0 and a type TYPE, return a simplified version
11464 of an indirection through OP0, or NULL_TREE if no simplification is
11465 possible. */
11467 tree
11469 {
11471 tree subtype;
11479 {
11482 /* *&p => p */
11485 /* *(foo *)&fooarray => fooarray[0] */
11488 {
11494 }
11495 }
11497 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
11500 {
11501 tree type_domain;
11508 }
11511 }
11513 /* Builds an expression for an indirection through T, simplifying some
11514 cases. */
11516 tree
11518 {
11524 else
11526 }
11528 /* Given an INDIRECT_REF T, return either T or a simplified version. */
11530 tree
11532 {
11537 else
11539 }
11541 /* Strip non-trapping, non-side-effecting tree nodes from an expression
11542 whose result is ignored. The type of the returned tree need not be
11543 the same as the original expression. */
11545 tree
11547 {
11553 {
11564 else
11570 {
11586 }
11591 }
11592 }
11594 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
11595 This can only be applied to objects of a sizetype. */
11597 tree
11599 {
11606 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
11607 have to do anything. Only do this when we are not given a const,
11608 because in that case, this check is more expensive than just
11609 doing it. */
11611 {
11616 }
11618 /* If divisor is a power of two, simplify this to bit manipulation. */
11620 {
11621 tree t;
11627 }
11628 else
11629 {
11634 }
11637 }
11639 /* Likewise, but round down. */
11641 tree
11643 {
11650 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
11651 have to do anything. Only do this when we are not given a const,
11652 because in that case, this check is more expensive than just
11653 doing it. */
11655 {
11660 }
11662 /* If divisor is a power of two, simplify this to bit manipulation. */
11664 {
11665 tree t;
11669 }
11670 else
11671 {
11676 }
11679 }
11681 /* Returns the pointer to the base of the object addressed by EXP and
11682 extracts the information about the offset of the access, storing it
11683 to PBITPOS and POFFSET. */
11685 static tree
11688 {
11689 tree core;
11692 HOST_WIDE_INT bitsize;
11695 {
11700 }
11701 else
11702 {
11706 }
11709 }
11711 /* Returns true if addresses of E1 and E2 differ by a constant, false
11712 otherwise. If they do, E1 - E2 is stored in *DIFF. */
11714 bool
11716 {
11730 {
11740 }
11742 {
11743 /* If only one of the offsets is non-constant, the difference cannot
11744 be a constant. */
11746 }
11747 else
11752 }
11754 /* Simplify the floating point expression EXP when the sign of the
11755 result is not significant. Return NULL_TREE if no simplification
11756 is possible. */
11758 tree
11760 {
11764 {
11784 }
11786 }