| blob | 07da71ae1968b181339e82e1b2cf452ed01c1a5d |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
129 HOST_WIDE_INT *,
162 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
163 Otherwise, return LOC. */
165 static location_t
167 {
170 }
172 /* Similar to protected_set_expr_location, but never modify x in place,
173 if location can and needs to be set, unshare it. */
177 {
183 {
186 }
188 }
189 \f
190 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
191 division and returns the quotient. Otherwise returns
192 NULL_TREE. */
194 tree
196 {
197 widest_int quo;
204 }
205 \f
206 /* This is nonzero if we should defer warnings about undefined
207 overflow. This facility exists because these warnings are a
208 special case. The code to estimate loop iterations does not want
209 to issue any warnings, since it works with expressions which do not
210 occur in user code. Various bits of cleanup code call fold(), but
211 only use the result if it has certain characteristics (e.g., is a
212 constant); that code only wants to issue a warning if the result is
213 used. */
217 /* If a warning about undefined overflow is deferred, this is the
218 warning. Note that this may cause us to turn two warnings into
219 one, but that is fine since it is sufficient to only give one
220 warning per expression. */
224 /* If a warning about undefined overflow is deferred, this is the
225 level at which the warning should be emitted. */
229 /* Start deferring overflow warnings. We could use a stack here to
230 permit nested calls, but at present it is not necessary. */
232 void
234 {
236 }
238 /* Stop deferring overflow warnings. If there is a pending warning,
239 and ISSUE is true, then issue the warning if appropriate. STMT is
240 the statement with which the warning should be associated (used for
241 location information); STMT may be NULL. CODE is the level of the
242 warning--a warn_strict_overflow_code value. This function will use
243 the smaller of CODE and the deferred code when deciding whether to
244 issue the warning. CODE may be zero to mean to always use the
245 deferred code. */
247 void
249 {
251 location_t locus;
256 {
262 }
273 /* Use the smallest code level when deciding to issue the
274 warning. */
283 else
286 }
288 /* Stop deferring overflow warnings, ignoring any deferred
289 warnings. */
291 void
293 {
295 }
297 /* Whether we are deferring overflow warnings. */
299 bool
301 {
303 }
305 /* This is called when we fold something based on the fact that signed
306 overflow is undefined. */
308 static void
310 {
312 {
315 {
318 }
319 }
322 }
323 \f
324 /* Return true if the built-in mathematical function specified by CODE
325 is odd, i.e. -f(x) == f(-x). */
327 static bool
329 {
331 {
365 }
367 }
369 /* Check whether we may negate an integer constant T without causing
370 overflow. */
372 bool
374 {
375 tree type;
384 }
386 /* Determine whether an expression T can be cheaply negated using
387 the function negate_expr without introducing undefined overflow. */
389 static bool
391 {
392 tree type;
401 {
406 /* Check that -CST will not overflow type. */
419 /* We want to canonicalize to positive real constants. Pretend
420 that only negative ones can be easily negated. */
428 {
439 }
452 /* -(A + B) -> (-B) - A. */
457 /* -(A + B) -> (-A) - B. */
461 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
471 /* Fall through. */
482 /* In general we can't negate A / B, because if A is INT_MIN and
483 B is 1, we may turn this into INT_MIN / -1 which is undefined
484 and actually traps on some architectures. But if overflow is
485 undefined, we can negate, because - (INT_MIN / 1) is an
486 overflow. */
488 {
491 /* If overflow is undefined then we have to be careful because
492 we ask whether it's ok to associate the negate with the
493 division which is not ok for example for
494 -((a - b) / c) where (-(a - b)) / c may invoke undefined
495 overflow because of negating INT_MIN. So do not use
496 negate_expr_p here but open-code the two important cases. */
501 }
507 /* Negate -((double)float) as (double)(-float). */
509 {
513 }
517 /* Negate -f(x) as f(-x). */
523 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
525 {
529 }
534 }
536 }
538 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
539 simplification is possible.
540 If negate_expr_p would return true for T, NULL_TREE will never be
541 returned. */
543 static tree
545 {
547 tree tem;
550 {
551 /* Convert - (~A) to A + 1. */
577 {
582 }
586 {
591 {
595 }
598 }
621 {
622 /* -(A + B) -> (-B) - A. */
626 {
630 }
632 /* -(A + B) -> (-A) - B. */
634 {
638 }
639 }
643 /* - (A - B) -> B - A */
655 /* Fall through. */
659 {
668 }
674 /* In general we can't negate A / B, because if A is INT_MIN and
675 B is 1, we may turn this into INT_MIN / -1 which is undefined
676 and actually traps on some architectures. But if overflow is
677 undefined, we can negate, because - (INT_MIN / 1) is an
678 overflow. */
680 {
685 {
692 }
693 /* If overflow is undefined then we have to be careful because
694 we ask whether it's ok to associate the negate with the
695 division which is not ok for example for
696 -((a - b) / c) where (-(a - b)) / c may invoke undefined
697 overflow because of negating INT_MIN. So do not use
698 negate_expr_p here but open-code the two important cases. */
707 }
711 /* Convert -((double)float) into (double)(-float). */
713 {
717 }
721 /* Negate -f(x) as f(-x). */
724 {
730 }
734 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
736 {
739 {
746 }
747 }
752 }
755 }
757 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
758 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
759 return NULL_TREE. */
761 static tree
763 {
765 location_t loc;
778 }
779 \f
780 /* Split a tree IN into a constant, literal and variable parts that could be
781 combined with CODE to make IN. "constant" means an expression with
782 TREE_CONSTANT but that isn't an actual constant. CODE must be a
783 commutative arithmetic operation. Store the constant part into *CONP,
784 the literal in *LITP and return the variable part. If a part isn't
785 present, set it to null. If the tree does not decompose in this way,
786 return the entire tree as the variable part and the other parts as null.
788 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
789 case, we negate an operand that was subtracted. Except if it is a
790 literal for which we use *MINUS_LITP instead.
792 If NEGATE_P is true, we are negating all of IN, again except a literal
793 for which we use *MINUS_LITP instead.
795 If IN is itself a literal or constant, return it as appropriate.
797 Note that we do not guarantee that any of the three values will be the
798 same type as IN, but they will have the same signedness and mode. */
800 static tree
803 {
810 /* Strip any conversions that don't change the machine mode or signedness. */
819 /* We can associate addition and subtraction together (even
820 though the C standard doesn't say so) for integers because
821 the value is not affected. For reals, the value might be
822 affected, so we can't. */
825 {
831 /* First see if either of the operands is a literal, then a constant. */
844 /* If we haven't dealt with either operand, this is not a case we can
845 decompose. Otherwise, VAR is either of the ones remaining, if any. */
850 else
853 /* Now do any needed negations. */
860 }
863 {
864 /* -X - 1 is folded to ~X, undo that here. */
867 }
870 else
874 {
881 }
884 }
886 /* Re-associate trees split by the above function. T1 and T2 are
887 either expressions to associate or null. Return the new
888 expression, if any. LOC is the location of the new expression. If
889 we build an operation, do it in TYPE and with CODE. */
891 static tree
893 {
899 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
900 try to fold this since we will have infinite recursion. But do
901 deal with any NEGATE_EXPRs. */
904 {
906 {
919 }
921 {
924 }
928 }
932 }
933 \f
934 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
935 for use in int_const_binop, size_binop and size_diffop. */
937 static bool
939 {
946 {
955 }
960 }
963 /* Combine two integer constants ARG1 and ARG2 under operation CODE
964 to produce a new constant. Return NULL_TREE if we don't know how
965 to evaluate CODE at compile-time. */
967 static tree
970 {
971 wide_int res;
972 tree t;
981 {
997 {
1001 else
1003 }
1006 /* It's unclear from the C standard whether shifts can overflow.
1007 The following code ignores overflow; perhaps a C standard
1008 interpretation ruling is needed. */
1010 else
1017 {
1021 else
1023 }
1027 else
1106 }
1114 }
1116 tree
1118 {
1120 }
1122 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1123 constant. We assume ARG1 and ARG2 have the same data type, or at least
1124 are the same kind of constant and the same machine mode. Return zero if
1125 combining the constants is not allowed in the current operating mode. */
1127 static tree
1129 {
1130 /* Sanity check for the recursive cases. */
1138 {
1144 }
1147 {
1148 machine_mode mode;
1149 REAL_VALUE_TYPE d1;
1150 REAL_VALUE_TYPE d2;
1151 REAL_VALUE_TYPE value;
1152 REAL_VALUE_TYPE result;
1156 /* The following codes are handled by real_arithmetic. */
1158 {
1169 }
1177 /* Don't perform operation if we honor signaling NaNs and
1178 either operand is a NaN. */
1183 /* Don't perform operation if it would raise a division
1184 by zero exception. */
1190 /* If either operand is a NaN, just return it. Otherwise, set up
1191 for floating-point trap; we return an overflow. */
1200 /* Don't constant fold this floating point operation if
1201 the result has overflowed and flag_trapping_math. */
1209 /* Don't constant fold this floating point operation if the
1210 result may dependent upon the run-time rounding mode and
1211 flag_rounding_math is set, or if GCC's software emulation
1212 is unable to accurately represent the result. */
1222 }
1225 {
1226 FIXED_VALUE_TYPE f1;
1227 FIXED_VALUE_TYPE f2;
1228 FIXED_VALUE_TYPE result;
1233 /* The following codes are handled by fixed_arithmetic. */
1235 {
1247 {
1254 }
1259 }
1266 /* Propagate overflow flags. */
1270 }
1273 {
1282 {
1293 mpc_mul);
1307 mpc_div);
1308 /* Fallthru ... */
1314 {
1315 /* Keep this algorithm in sync with
1316 tree-complex.c:expand_complex_div_straight().
1318 Expand complex division to scalars, straightforward algorithm.
1319 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1320 t = br*br + bi*bi
1321 */
1322 tree magsquared
1326 tree t1
1330 tree t2
1337 }
1338 else
1339 {
1340 /* Keep this algorithm in sync with
1341 tree-complex.c:expand_complex_div_wide().
1343 Expand complex division to scalars, modified algorithm to minimize
1344 overflow with wide input ranges. */
1350 {
1351 /* In the TRUE branch, we compute
1352 ratio = br/bi;
1353 div = (br * ratio) + bi;
1354 tr = (ar * ratio) + ai;
1355 ti = (ai * ratio) - ar;
1356 tr = tr / div;
1357 ti = ti / div; */
1368 }
1369 else
1370 {
1371 /* In the FALSE branch, we compute
1372 ratio = d/c;
1373 divisor = (d * ratio) + c;
1374 tr = (b * ratio) + a;
1375 ti = b - (a * ratio);
1376 tr = tr / div;
1377 ti = ti / div; */
1389 }
1390 }
1395 }
1399 }
1403 {
1409 {
1415 /* It is possible that const_binop cannot handle the given
1416 code and return NULL_TREE */
1419 }
1422 }
1424 /* Shifts allow a scalar offset for a vector. */
1427 {
1433 {
1438 /* It is possible that const_binop cannot handle the given
1439 code and return NULL_TREE. */
1442 }
1445 }
1447 }
1449 /* Overload that adds a TYPE parameter to be able to dispatch
1450 to fold_relational_const. */
1452 tree
1454 {
1458 /* ??? Until we make the const_binop worker take the type of the
1459 result as argument put those cases that need it here. */
1461 {
1472 {
1488 {
1494 }
1497 }
1503 {
1528 {
1541 }
1544 }
1547 }
1549 /* Make sure type and arg0 have the same saturating flag. */
1553 }
1555 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1556 Return zero if computing the constants is not possible. */
1558 tree
1560 {
1562 {
1563 CASE_CONVERT:
1578 {
1579 /* Can't call fold_negate_const directly here as that doesn't
1580 handle all cases and we might not be able to negate some
1581 constants. */
1586 }
1595 {
1599 }
1605 /* Perform BIT_NOT_EXPR on each element individually. */
1607 {
1609 tree elem;
1614 {
1620 }
1623 }
1645 {
1664 else
1668 {
1672 }
1675 }
1680 {
1694 {
1699 }
1702 {
1706 }
1709 }
1713 }
1716 }
1718 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1719 indicates which particular sizetype to create. */
1721 tree
1723 {
1725 }
1726 \f
1727 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1728 is a tree code. The type of the result is taken from the operands.
1729 Both must be equivalent integer types, ala int_binop_types_match_p.
1730 If the operands are constant, so is the result. */
1732 tree
1734 {
1743 /* Handle the special case of two integer constants faster. */
1745 {
1746 /* And some specific cases even faster than that. */
1748 {
1753 }
1755 {
1758 }
1760 {
1763 }
1765 /* Handle general case of two integer constants. For sizetype
1766 constant calculations we always want to know about overflow,
1767 even in the unsigned case. */
1769 }
1772 }
1774 /* Given two values, either both of sizetype or both of bitsizetype,
1775 compute the difference between the two values. Return the value
1776 in signed type corresponding to the type of the operands. */
1778 tree
1780 {
1782 tree ctype;
1787 /* If the type is already signed, just do the simple thing. */
1795 else
1798 /* If either operand is not a constant, do the conversions to the signed
1799 type and subtract. The hardware will do the right thing with any
1800 overflow in the subtraction. */
1806 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1807 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1808 overflow) and negate (which can't either). Special-case a result
1809 of zero while we're here. */
1815 else
1819 MINUS_EXPR,
1821 }
1822 \f
1823 /* A subroutine of fold_convert_const handling conversions of an
1824 INTEGER_CST to another integer type. */
1826 static tree
1828 {
1829 /* Given an integer constant, make new constant with new type,
1830 appropriately sign-extended or truncated. Use widest_int
1831 so that any extension is done according ARG1's type. */
1835 }
1837 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1838 to an integer type. */
1840 static tree
1842 {
1844 tree t;
1846 /* The following code implements the floating point to integer
1847 conversion rules required by the Java Language Specification,
1848 that IEEE NaNs are mapped to zero and values that overflow
1849 the target precision saturate, i.e. values greater than
1850 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1851 are mapped to INT_MIN. These semantics are allowed by the
1852 C and C++ standards that simply state that the behavior of
1853 FP-to-integer conversion is unspecified upon overflow. */
1855 wide_int val;
1856 REAL_VALUE_TYPE r;
1860 {
1867 }
1869 /* If R is NaN, return zero and show we have an overflow. */
1871 {
1874 }
1876 /* See if R is less than the lower bound or greater than the
1877 upper bound. */
1880 {
1884 {
1887 }
1888 }
1891 {
1894 {
1897 {
1900 }
1901 }
1902 }
1909 }
1911 /* A subroutine of fold_convert_const handling conversions of a
1912 FIXED_CST to an integer type. */
1914 static tree
1916 {
1917 tree t;
1921 /* Right shift FIXED_CST to temp by fbit. */
1925 {
1927 HOST_BITS_PER_DOUBLE_INT,
1930 /* Left shift temp to temp_trunc by fbit. */
1932 HOST_BITS_PER_DOUBLE_INT,
1934 }
1935 else
1936 {
1939 }
1941 /* If FIXED_CST is negative, we need to round the value toward 0.
1942 By checking if the fractional bits are not zero to add 1 to temp. */
1948 /* Given a fixed-point constant, make new constant with new type,
1949 appropriately sign-extended or truncated. */
1957 }
1959 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1960 to another floating point type. */
1962 static tree
1964 {
1965 REAL_VALUE_TYPE value;
1966 tree t;
1971 /* If converting an infinity or NAN to a representation that doesn't
1972 have one, set the overflow bit so that we can produce some kind of
1973 error message at the appropriate point if necessary. It's not the
1974 most user-friendly message, but it's better than nothing. */
1981 /* Regular overflow, conversion produced an infinity in a mode that
1982 can't represent them. */
1987 else
1990 }
1992 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1993 to a floating point type. */
1995 static tree
1997 {
1998 REAL_VALUE_TYPE value;
1999 tree t;
2006 }
2008 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2009 to another fixed-point type. */
2011 static tree
2013 {
2014 FIXED_VALUE_TYPE value;
2015 tree t;
2022 /* Propagate overflow flags. */
2026 }
2028 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2029 to a fixed-point type. */
2031 static tree
2033 {
2034 FIXED_VALUE_TYPE value;
2035 tree t;
2037 double_int di;
2044 else
2052 /* Propagate overflow flags. */
2056 }
2058 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2059 to a fixed-point type. */
2061 static tree
2063 {
2064 FIXED_VALUE_TYPE value;
2065 tree t;
2073 /* Propagate overflow flags. */
2077 }
2079 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2080 type TYPE. If no simplification can be done return NULL_TREE. */
2082 static tree
2084 {
2090 {
2097 }
2099 {
2106 }
2108 {
2115 }
2117 }
2119 /* Construct a vector of zero elements of vector type TYPE. */
2121 static tree
2123 {
2124 tree t;
2128 }
2130 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2132 bool
2134 {
2149 {
2168 }
2169 }
2171 /* Convert expression ARG to type TYPE. Used by the middle-end for
2172 simple conversions in preference to calling the front-end's convert. */
2174 tree
2176 {
2178 tree tem;
2189 {
2192 /* Handle conversions between pointers to different address spaces. */
2197 /* fall through */
2202 {
2206 }
2220 {
2224 }
2226 {
2230 }
2232 {
2236 }
2239 {
2257 }
2262 {
2266 }
2269 {
2283 }
2287 {
2296 integer_zero_node));
2298 {
2302 {
2308 }
2316 }
2320 }
2338 }
2339 fold_convert_exit:
2342 }
2343 \f
2344 /* Return false if expr can be assumed not to be an lvalue, true
2345 otherwise. */
2347 static bool
2349 {
2350 /* We only need to wrap lvalue tree codes. */
2352 {
2383 /* Assume the worst for front-end tree codes. */
2387 }
2390 }
2392 /* Return an expr equal to X but certainly not valid as an lvalue. */
2394 tree
2396 {
2397 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2398 us. */
2405 }
2407 /* When pedantic, return an expr equal to X but certainly not valid as a
2408 pedantic lvalue. Otherwise, return X. */
2410 static tree
2412 {
2414 }
2415 \f
2416 /* Given a tree comparison code, return the code that is the logical inverse.
2417 It is generally not safe to do this for floating-point comparisons, except
2418 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2419 ERROR_MARK in this case. */
2421 enum tree_code
2423 {
2429 {
2460 }
2461 }
2463 /* Similar, but return the comparison that results if the operands are
2464 swapped. This is safe for floating-point. */
2466 enum tree_code
2468 {
2470 {
2496 }
2497 }
2500 /* Convert a comparison tree code from an enum tree_code representation
2501 into a compcode bit-based encoding. This function is the inverse of
2502 compcode_to_comparison. */
2504 static enum comparison_code
2506 {
2508 {
2539 }
2540 }
2542 /* Convert a compcode bit-based encoding of a comparison operator back
2543 to GCC's enum tree_code representation. This function is the
2544 inverse of comparison_to_compcode. */
2546 static enum tree_code
2548 {
2550 {
2581 }
2582 }
2584 /* Return a tree for the comparison which is the combination of
2585 doing the AND or OR (depending on CODE) of the two operations LCODE
2586 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2587 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2588 if this makes the transformation invalid. */
2590 tree
2595 {
2602 {
2613 }
2616 {
2617 /* Eliminate unordered comparisons, as well as LTGT and ORD
2618 which are not used unless the mode has NaNs. */
2624 }
2626 {
2627 /* Check that the original operation and the optimized ones will trap
2628 under the same condition. */
2639 /* In a short-circuited boolean expression the LHS might be
2640 such that the RHS, if evaluated, will never trap. For
2641 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2642 if neither x nor y is NaN. (This is a mixed blessing: for
2643 example, the expression above will never trap, hence
2644 optimizing it to x < y would be invalid). */
2649 /* If the comparison was short-circuited, and only the RHS
2650 trapped, we may now generate a spurious trap. */
2655 /* If we changed the conditions that cause a trap, we lose. */
2658 }
2664 else
2665 {
2670 }
2671 }
2672 \f
2673 /* Return nonzero if two operands (typically of the same tree node)
2674 are necessarily equal. If either argument has side-effects this
2675 function returns zero. FLAGS modifies behavior as follows:
2677 If OEP_ONLY_CONST is set, only return nonzero for constants.
2678 This function tests whether the operands are indistinguishable;
2679 it does not test whether they are equal using C's == operation.
2680 The distinction is important for IEEE floating point, because
2681 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2682 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2684 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2685 even though it may hold multiple values during a function.
2686 This is because a GCC tree node guarantees that nothing else is
2687 executed between the evaluation of its "operands" (which may often
2688 be evaluated in arbitrary order). Hence if the operands themselves
2689 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2690 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2691 unset means assuming isochronic (or instantaneous) tree equivalence.
2692 Unless comparing arbitrary expression trees, such as from different
2693 statements, this flag can usually be left unset.
2695 If OEP_PURE_SAME is set, then pure functions with identical arguments
2696 are considered the same. It is used when the caller has other ways
2697 to ensure that global memory is unchanged in between. */
2699 int
2701 {
2702 /* If either is ERROR_MARK, they aren't equal. */
2708 /* Similar, if either does not have a type (like a released SSA name),
2709 they aren't equal. */
2713 /* Check equality of integer constants before bailing out due to
2714 precision differences. */
2718 /* If both types don't have the same signedness, then we can't consider
2719 them equal. We must check this before the STRIP_NOPS calls
2720 because they may change the signedness of the arguments. As pointers
2721 strictly don't have a signedness, require either two pointers or
2722 two non-pointers as well. */
2727 /* We cannot consider pointers to different address space equal. */
2733 /* If both types don't have the same precision, then it is not safe
2734 to strip NOPs. */
2742 /* In case both args are comparisons but with different comparison
2743 code, try to swap the comparison operands of one arg to produce
2744 a match and compare that variant. */
2748 {
2756 }
2759 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2763 /* This is needed for conversions and for COMPONENT_REF.
2764 Might as well play it safe and always test this. */
2770 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2771 We don't care about side effects in that case because the SAVE_EXPR
2772 takes care of that for us. In all other cases, two expressions are
2773 equal if they have no side effects. If we have two identical
2774 expressions with side effects that should be treated the same due
2775 to the only side effects being identical SAVE_EXPR's, that will
2776 be detected in the recursive calls below.
2777 If we are taking an invariant address of two identical objects
2778 they are necessarily equal as well. */
2785 /* Next handle constant cases, those for which we can return 1 even
2786 if ONLY_CONST is set. */
2789 {
2804 {
2805 /* If we do not distinguish between signed and unsigned zero,
2806 consider them equal. */
2809 }
2813 {
2820 {
2824 }
2826 }
2830 flags)
2832 flags));
2846 }
2851 /* Define macros to test an operand from arg0 and arg1 for equality and a
2852 variant that allows null and views null as being different from any
2853 non-null value. In the latter case, if either is null, the both
2854 must be; otherwise, do the normal comparison. */
2855 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2856 TREE_OPERAND (arg1, N), flags)
2858 #define OP_SAME_WITH_NULL(N) \
2859 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2860 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2863 {
2865 /* Two conversions are equal only if signedness and modes match. */
2867 {
2868 CASE_CONVERT:
2876 }
2886 /* For commutative ops, allow the other order. */
2894 /* If either of the pointer (or reference) expressions we are
2895 dereferencing contain a side effect, these cannot be equal,
2896 but their addresses can be. */
2903 {
2914 /* Require equal extra operands and then fall through to MEM_REF
2915 handling of the two common operands. */
2920 /* Fallthru. */
2923 /* Require equal access sizes, and similar pointer types.
2924 We can have incomplete types for array references of
2925 variable-sized arrays from the Fortran frontend
2926 though. Also verify the types are compatible. */
2933 && alias_ptr_types_compatible_p
2940 /* Operands 2 and 3 may be null.
2941 Compare the array index by value if it is constant first as we
2942 may have different types but same value here. */
2953 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2954 may be NULL when we're called to compare MEM_EXPRs. */
2969 }
2973 {
2987 /* The multiplcation operands are commutative. */
2988 /* FALLTHRU */
2996 /* Otherwise take into account this is a commutative operation. */
3009 }
3013 {
3015 /* If the CALL_EXPRs call different functions, then they
3016 clearly can not be equal. */
3018 flags))
3021 {
3025 else
3029 }
3031 /* Now see if all the arguments are the same. */
3032 {
3043 /* If we get here and both argument lists are exhausted
3044 then the CALL_EXPRs are equal. */
3046 }
3049 }
3052 /* Consider __builtin_sqrt equal to sqrt. */
3060 }
3062 #undef OP_SAME
3063 #undef OP_SAME_WITH_NULL
3064 }
3065 \f
3066 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3067 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3069 When in doubt, return 0. */
3071 static int
3073 {
3085 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3086 and see if the inner values are the same. This removes any
3087 signedness comparison, which doesn't matter here. */
3094 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3095 actual comparison operand, ARG0.
3097 First throw away any conversions to wider types
3098 already present in the operands. */
3107 {
3110 /* Make sure shorter operand is extended the right way
3111 to match the longer operand. */
3117 }
3120 }
3121 \f
3122 /* See if ARG is an expression that is either a comparison or is performing
3123 arithmetic on comparisons. The comparisons must only be comparing
3124 two different values, which will be stored in *CVAL1 and *CVAL2; if
3125 they are nonzero it means that some operands have already been found.
3126 No variables may be used anywhere else in the expression except in the
3127 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3128 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3130 If this is true, return 1. Otherwise, return zero. */
3132 static int
3134 {
3138 /* We can handle some of the tcc_expression cases here. */
3148 {
3149 /* If we've already found a CVAL1 or CVAL2, this expression is
3150 two complex to handle. */
3156 }
3159 {
3182 /* First see if we can handle the first operand, then the second. For
3183 the second operand, we know *CVAL1 can't be zero. It must be that
3184 one side of the comparison is each of the values; test for the
3185 case where this isn't true by failing if the two operands
3186 are the same. */
3195 ;
3199 ;
3200 else
3204 ;
3208 ;
3209 else
3216 }
3217 }
3218 \f
3219 /* ARG is a tree that is known to contain just arithmetic operations and
3220 comparisons. Evaluate the operations in the tree substituting NEW0 for
3221 any occurrence of OLD0 as an operand of a comparison and likewise for
3222 NEW1 and OLD1. */
3224 static tree
3227 {
3232 /* We can handle some of the tcc_expression cases here. */
3240 {
3255 {
3274 }
3275 /* Fall through - ??? */
3278 {
3282 /* We need to check both for exact equality and tree equality. The
3283 former will be true if the operand has a side-effect. In that
3284 case, we know the operand occurred exactly once. */
3297 }
3301 }
3302 }
3303 \f
3304 /* Return a tree for the case when the result of an expression is RESULT
3305 converted to TYPE and OMITTED was previously an operand of the expression
3306 but is now not needed (e.g., we folded OMITTED * 0).
3308 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3309 the conversion of RESULT to TYPE. */
3311 tree
3313 {
3316 /* If the resulting operand is an empty statement, just return the omitted
3317 statement casted to void. */
3327 }
3329 /* Return a tree for the case when the result of an expression is RESULT
3330 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3331 of the expression but are now not needed.
3333 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3334 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3335 evaluated before OMITTED2. Otherwise, if neither has side effects,
3336 just do the conversion of RESULT to TYPE. */
3338 tree
3341 {
3350 }
3352 \f
3353 /* Return a simplified tree node for the truth-negation of ARG. This
3354 never alters ARG itself. We assume that ARG is an operation that
3355 returns a truth value (0 or 1).
3357 FIXME: one would think we would fold the result, but it causes
3358 problems with the dominator optimizer. */
3360 static tree
3362 {
3367 /* If this is a comparison, we can simply invert it, except for
3368 floating-point non-equality comparisons, in which case we just
3369 enclose a TRUTH_NOT_EXPR around what we have. */
3372 {
3375 && flag_trapping_math
3386 }
3389 {
3408 /* Here we can invert either operand. We invert the first operand
3409 unless the second operand is a TRUTH_NOT_EXPR in which case our
3410 result is the XOR of the first operand with the inside of the
3411 negation of the second operand. */
3416 else
3439 {
3446 /* A COND_EXPR may have a throw as one operand, which
3447 then has void type. Just leave void operands
3448 as they are. */
3454 }
3466 CASE_CONVERT:
3470 /* ... fall through ... */
3492 }
3493 }
3495 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3496 assume that ARG is an operation that returns a truth value (0 or 1
3497 for scalars, 0 or -1 for vectors). Return the folded expression if
3498 folding is successful. Otherwise, return NULL_TREE. */
3500 static tree
3502 {
3505 ? BIT_NOT_EXPR
3508 }
3510 /* Return a simplified tree node for the truth-negation of ARG. This
3511 never alters ARG itself. We assume that ARG is an operation that
3512 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3514 tree
3516 {
3522 ? BIT_NOT_EXPR
3525 }
3527 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3528 operands are another bit-wise operation with a common input. If so,
3529 distribute the bit operations to save an operation and possibly two if
3530 constants are involved. For example, convert
3531 (A | B) & (A | C) into A | (B & C)
3532 Further simplification will occur if B and C are constants.
3534 If this optimization cannot be done, 0 will be returned. */
3536 static tree
3539 {
3540 tree common;
3550 {
3554 }
3556 {
3560 }
3562 {
3566 }
3568 {
3572 }
3573 else
3581 }
3583 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3584 with code CODE. This optimization is unsafe. */
3585 static tree
3588 {
3592 /* (A / C) +- (B / C) -> (A +- B) / C. */
3602 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3607 {
3619 }
3622 }
3623 \f
3624 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3625 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3627 static tree
3630 {
3634 {
3641 }
3655 }
3657 /* Optimize a bit-field compare.
3659 There are two cases: First is a compare against a constant and the
3660 second is a comparison of two items where the fields are at the same
3661 bit position relative to the start of a chunk (byte, halfword, word)
3662 large enough to contain it. In these cases we can avoid the shift
3663 implicit in bitfield extractions.
3665 For constants, we emit a compare of the shifted constant with the
3666 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3667 compared. For two fields at the same position, we do the ANDs with the
3668 similar mask and compare the result of the ANDs.
3670 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3671 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3672 are the left and right operands of the comparison, respectively.
3674 If the optimization described above can be done, we return the resulting
3675 tree. Otherwise we return zero. */
3677 static tree
3680 {
3683 tree unsigned_type;
3689 tree mask;
3690 tree offset;
3692 /* Get all the information about the extractions being done. If the bit size
3693 if the same as the size of the underlying object, we aren't doing an
3694 extraction at all and so can do nothing. We also don't want to
3695 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3696 then will no longer be able to replace it. */
3704 {
3705 /* If this is not a constant, we can only do something if bit positions,
3706 sizes, and signedness are the same. */
3714 }
3716 /* See if we can find a mode to refer to this field. We should be able to,
3717 but fail if we can't. */
3726 /* Set signed and unsigned types of the precision of this mode for the
3727 shifts below. */
3730 /* Compute the bit position and size for the new reference and our offset
3731 within it. If the new reference is the same size as the original, we
3732 won't optimize anything, so return zero. */
3742 /* Make the mask to be used against the extracted field. */
3749 /* If not comparing with constant, just rework the comparison
3750 and return. */
3754 unsigned_type,
3757 mask),
3760 unsigned_type,
3763 mask));
3765 /* Otherwise, we are handling the constant case. See if the constant is too
3766 big for the field. Warn and return a tree of for 0 (false) if so. We do
3767 this not only for its own sake, but to avoid having to test for this
3768 error case below. If we didn't, we might generate wrong code.
3770 For unsigned fields, the constant shifted right by the field length should
3771 be all zero. For signed fields, the high-order bits should agree with
3772 the sign bit. */
3775 {
3777 {
3781 }
3782 }
3783 else
3784 {
3787 {
3791 }
3792 }
3794 /* Single-bit compares should always be against zero. */
3796 {
3799 }
3801 /* Make a new bitfield reference, shift the constant over the
3802 appropriate number of bits and mask it with the computed mask
3803 (in case this was a signed field). If we changed it, make a new one. */
3810 mask);
3815 }
3816 \f
3817 /* Subroutine for fold_truth_andor_1: decode a field reference.
3819 If EXP is a comparison reference, we return the innermost reference.
3821 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3822 set to the starting bit number.
3824 If the innermost field can be completely contained in a mode-sized
3825 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3827 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3828 otherwise it is not changed.
3830 *PUNSIGNEDP is set to the signedness of the field.
3832 *PMASK is set to the mask used. This is either contained in a
3833 BIT_AND_EXPR or derived from the width of the field.
3835 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3837 Return 0 if this is not a component reference or is one that we can't
3838 do anything with. */
3840 static tree
3845 {
3849 tree unsigned_type;
3852 /* All the optimizations using this function assume integer fields.
3853 There are problems with FP fields since the type_for_size call
3854 below can fail for, e.g., XFmode. */
3858 /* We are interested in the bare arrangement of bits, so strip everything
3859 that doesn't affect the machine mode. However, record the type of the
3860 outermost expression if it may matter below. */
3867 {
3873 }
3882 /* If the number of bits in the reference is the same as the bitsize of
3883 the outer type, then the outer type gives the signedness. Otherwise
3884 (in case of a small bitfield) the signedness is unchanged. */
3888 /* Compute the mask to access the bitfield. */
3897 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3905 }
3907 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3908 bit positions and MASK is SIGNED. */
3910 static int
3912 {
3916 /* If this function returns true when the type of the mask is
3917 UNSIGNED, then there will be errors. In particular see
3918 gcc.c-torture/execute/990326-1.c. There does not appear to be
3919 any documentation paper trail as to why this is so. But the pre
3920 wide-int worked with that restriction and it has been preserved
3921 here. */
3926 }
3928 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3929 represents the sign bit of EXP's type. If EXP represents a sign
3930 or zero extension, also test VAL against the unextended type.
3931 The return value is the (sub)expression whose sign bit is VAL,
3932 or NULL_TREE otherwise. */
3934 tree
3936 {
3938 tree t;
3940 /* Tree EXP must have an integral type. */
3945 /* Tree VAL must be an integer constant. */
3954 /* Handle extension from a narrower type. */
3960 }
3962 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3963 to be evaluated unconditionally. */
3965 static int
3967 {
3968 /* Strip any conversions that don't change the machine mode. */
3977 /* Don't regard global variables as simple. They may be
3978 allocated in ways unknown to the compiler (shared memory,
3979 #pragma weak, etc). */
3982 /* Weakrefs are not safe to be read, since they can be NULL.
3983 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3984 have DECL_WEAK flag set. */
3986 /* Loading a static variable is unduly expensive, but global
3987 registers aren't expensive. */
3989 }
3991 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3992 to be evaluated unconditionally.
3993 I addition to simple_operand_p, we assume that comparisons, conversions,
3994 and logic-not operations are simple, if their operands are simple, too. */
3996 static bool
3998 {
4018 }
4020 \f
4021 /* The following functions are subroutines to fold_range_test and allow it to
4022 try to change a logical combination of comparisons into a range test.
4024 For example, both
4025 X == 2 || X == 3 || X == 4 || X == 5
4026 and
4027 X >= 2 && X <= 5
4028 are converted to
4029 (unsigned) (X - 2) <= 3
4031 We describe each set of comparisons as being either inside or outside
4032 a range, using a variable named like IN_P, and then describe the
4033 range with a lower and upper bound. If one of the bounds is omitted,
4034 it represents either the highest or lowest value of the type.
4036 In the comments below, we represent a range by two numbers in brackets
4037 preceded by a "+" to designate being inside that range, or a "-" to
4038 designate being outside that range, so the condition can be inverted by
4039 flipping the prefix. An omitted bound is represented by a "-". For
4040 example, "- [-, 10]" means being outside the range starting at the lowest
4041 possible value and ending at 10, in other words, being greater than 10.
4042 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4043 always false.
4045 We set up things so that the missing bounds are handled in a consistent
4046 manner so neither a missing bound nor "true" and "false" need to be
4047 handled using a special case. */
4049 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4050 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4051 and UPPER1_P are nonzero if the respective argument is an upper bound
4052 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4053 must be specified for a comparison. ARG1 will be converted to ARG0's
4054 type if both are specified. */
4056 static tree
4059 {
4060 tree tem;
4064 /* If neither arg represents infinity, do the normal operation.
4065 Else, if not a comparison, return infinity. Else handle the special
4066 comparison rules. Note that most of the cases below won't occur, but
4067 are handled for consistency. */
4070 {
4075 }
4080 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4081 for neither. In real maths, we cannot assume open ended ranges are
4082 the same. But, this is computer arithmetic, where numbers are finite.
4083 We can therefore make the transformation of any unbounded range with
4084 the value Z, Z being greater than any representable number. This permits
4085 us to treat unbounded ranges as equal. */
4089 {
4110 }
4113 }
4114 \f
4115 /* Helper routine for make_range. Perform one step for it, return
4116 new expression if the loop should continue or NULL_TREE if it should
4117 stop. */
4119 tree
4123 {
4129 {
4131 /* We can only do something if the range is testing for zero. */
4140 /* We can only do something if the range is testing for zero
4141 and if the second operand is an integer constant. Note that
4142 saying something is "in" the range we make is done by
4143 complementing IN_P since it will set in the initial case of
4144 being not equal to zero; "out" is leaving it alone. */
4151 {
4172 }
4174 /* If this is an unsigned comparison, we also know that EXP is
4175 greater than or equal to zero. We base the range tests we make
4176 on that fact, so we record it here so we can parse existing
4177 range tests. We test arg0_type since often the return type
4178 of, e.g. EQ_EXPR, is boolean. */
4180 {
4184 NULL_TREE))
4189 /* If the high bound is missing, but we have a nonzero low
4190 bound, reverse the range so it goes from zero to the low bound
4191 minus 1. */
4193 {
4198 }
4199 }
4207 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4208 low and high are non-NULL, then normalize will DTRT. */
4211 {
4216 }
4218 /* (-x) IN [a,b] -> x in [-b, -a] */
4230 /* ~ X -> -X - 1 */
4239 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4240 move a constant to the other side. */
4245 /* If EXP is signed, any overflow in the computation is undefined,
4246 so we don't worry about it so long as our computations on
4247 the bounds don't overflow. For unsigned, overflow is defined
4248 and this is exactly the right thing. */
4260 normalize:
4261 /* Check for an unsigned range which has wrapped around the maximum
4262 value thus making n_high < n_low, and normalize it. */
4264 {
4270 /* If the range is of the form +/- [ x+1, x ], we won't
4271 be able to normalize it. But then, it represents the
4272 whole range or the empty set, so make it
4273 +/- [ -, - ]. */
4277 else
4279 }
4280 else
4288 CASE_CONVERT:
4306 /* If we're converting arg0 from an unsigned type, to exp,
4307 a signed type, we will be doing the comparison as unsigned.
4308 The tests above have already verified that LOW and HIGH
4309 are both positive.
4311 So we have to ensure that we will handle large unsigned
4312 values the same way that the current signed bounds treat
4313 negative values. */
4316 {
4317 tree high_positive;
4318 tree equiv_type;
4319 /* For fixed-point modes, we need to pass the saturating flag
4320 as the 2nd parameter. */
4322 equiv_type
4325 else
4326 equiv_type
4329 /* A range without an upper bound is, naturally, unbounded.
4330 Since convert would have cropped a very large value, use
4331 the max value for the destination type. */
4332 high_positive
4339 high_positive),
4342 /* If the low bound is specified, "and" the range with the
4343 range for which the original unsigned value will be
4344 positive. */
4346 {
4349 integer_zero_node),
4350 high_positive))
4354 }
4355 else
4356 {
4357 /* Otherwise, "or" the range with the range of the input
4358 that will be interpreted as negative. */
4361 integer_zero_node),
4362 high_positive))
4366 }
4367 }
4376 }
4377 }
4379 /* Given EXP, a logical expression, set the range it is testing into
4380 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4381 actually being tested. *PLOW and *PHIGH will be made of the same
4382 type as the returned expression. If EXP is not a comparison, we
4383 will most likely not be returning a useful value and range. Set
4384 *STRICT_OVERFLOW_P to true if the return value is only valid
4385 because signed overflow is undefined; otherwise, do not change
4386 *STRICT_OVERFLOW_P. */
4388 tree
4391 {
4399 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4400 and see if we can refine the range. Some of the cases below may not
4401 happen, but it doesn't seem worth worrying about this. We "continue"
4402 the outer loop when we've changed something; otherwise we "break"
4403 the switch, which will "break" the while. */
4409 {
4415 {
4423 }
4432 }
4434 /* If EXP is a constant, we can evaluate whether this is true or false. */
4436 {
4443 }
4447 }
4448 \f
4449 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4450 type, TYPE, return an expression to test if EXP is in (or out of, depending
4451 on IN_P) the range. Return 0 if the test couldn't be created. */
4453 tree
4456 {
4459 #ifdef HAVE_canonicalize_funcptr_for_compare
4460 /* Disable this optimization for function pointer expressions
4461 on targets that require function pointer canonicalization. */
4466 #endif
4469 {
4475 }
4493 {
4495 {
4499 }
4501 }
4503 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4505 {
4509 {
4511 {
4514 etype
4516 else
4519 }
4522 }
4523 }
4525 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4526 This requires wrap-around arithmetics for the type of the expression.
4527 First make sure that arithmetics in this type is valid, then make sure
4528 that it wraps around. */
4534 {
4537 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4538 for the type in question, as we rely on this here. */
4548 else
4550 }
4560 {
4562 {
4567 }
4569 }
4577 }
4578 \f
4579 /* Return the predecessor of VAL in its type, handling the infinite case. */
4581 static tree
4583 {
4589 else
4592 }
4594 /* Return the successor of VAL in its type, handling the infinite case. */
4596 static tree
4598 {
4604 else
4607 }
4609 /* Given two ranges, see if we can merge them into one. Return 1 if we
4610 can, 0 if we can't. Set the output range into the specified parameters. */
4612 bool
4615 {
4619 tree tem;
4629 /* Make range 0 be the range that starts first, or ends last if they
4630 start at the same value. Swap them if it isn't. */
4633 || (lowequal
4636 {
4640 }
4642 /* Now flag two cases, whether the ranges are disjoint or whether the
4643 second range is totally subsumed in the first. Note that the tests
4644 below are simplified by the ones above. */
4650 /* We now have four cases, depending on whether we are including or
4651 excluding the two ranges. */
4653 {
4654 /* If they don't overlap, the result is false. If the second range
4655 is a subset it is the result. Otherwise, the range is from the start
4656 of the second to the end of the first. */
4661 else
4663 }
4666 {
4667 /* If they don't overlap, the result is the first range. If they are
4668 equal, the result is false. If the second range is a subset of the
4669 first, and the ranges begin at the same place, we go from just after
4670 the end of the second range to the end of the first. If the second
4671 range is not a subset of the first, or if it is a subset and both
4672 ranges end at the same place, the range starts at the start of the
4673 first range and ends just before the second range.
4674 Otherwise, we can't describe this as a single range. */
4680 {
4685 {
4686 /* We are in the weird situation where high0 > high1 but
4687 high1 has no successor. Punt. */
4689 }
4690 }
4692 {
4697 {
4698 /* low0 < low1 but low1 has no predecessor. Punt. */
4700 }
4701 }
4702 else
4704 }
4707 {
4708 /* If they don't overlap, the result is the second range. If the second
4709 is a subset of the first, the result is false. Otherwise,
4710 the range starts just after the first range and ends at the
4711 end of the second. */
4716 else
4717 {
4722 {
4723 /* high1 > high0 but high0 has no successor. Punt. */
4725 }
4726 }
4727 }
4729 else
4730 {
4731 /* The case where we are excluding both ranges. Here the complex case
4732 is if they don't overlap. In that case, the only time we have a
4733 range is if they are adjacent. If the second is a subset of the
4734 first, the result is the first. Otherwise, the range to exclude
4735 starts at the beginning of the first range and ends at the end of the
4736 second. */
4738 {
4743 else
4744 {
4745 /* Canonicalize - [min, x] into - [-, x]. */
4748 {
4753 /* FALLTHROUGH */
4766 }
4768 /* Canonicalize - [x, max] into - [x, -]. */
4771 {
4776 /* FALLTHROUGH */
4792 }
4794 /* The ranges might be also adjacent between the maximum and
4795 minimum values of the given type. For
4796 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4797 return + [x + 1, y - 1]. */
4799 {
4806 }
4807 else
4809 }
4810 }
4813 else
4815 }
4819 }
4820 \f
4822 /* Subroutine of fold, looking inside expressions of the form
4823 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4824 of the COND_EXPR. This function is being used also to optimize
4825 A op B ? C : A, by reversing the comparison first.
4827 Return a folded expression whose code is not a COND_EXPR
4828 anymore, or NULL_TREE if no folding opportunity is found. */
4830 static tree
4833 {
4838 tree tem;
4843 /* If we have A op 0 ? A : -A, consider applying the following
4844 transformations:
4846 A == 0? A : -A same as -A
4847 A != 0? A : -A same as A
4848 A >= 0? A : -A same as abs (A)
4849 A > 0? A : -A same as abs (A)
4850 A <= 0? A : -A same as -abs (A)
4851 A < 0? A : -A same as -abs (A)
4853 None of these transformations work for modes with signed
4854 zeros. If A is +/-0, the first two transformations will
4855 change the sign of the result (from +0 to -0, or vice
4856 versa). The last four will fix the sign of the result,
4857 even though the original expressions could be positive or
4858 negative, depending on the sign of A.
4860 Note that all these transformations are correct if A is
4861 NaN, since the two alternatives (A and -A) are also NaNs. */
4868 /* In the case that A is of the form X-Y, '-A' (arg2) may
4869 have already been folded to Y-X, check for that. */
4877 {
4891 /* Fall through. */
4913 }
4915 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4916 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4917 both transformations are correct when A is NaN: A != 0
4918 is then true, and A == 0 is false. */
4922 {
4927 }
4929 /* Try some transformations of A op B ? A : B.
4931 A == B? A : B same as B
4932 A != B? A : B same as A
4933 A >= B? A : B same as max (A, B)
4934 A > B? A : B same as max (B, A)
4935 A <= B? A : B same as min (A, B)
4936 A < B? A : B same as min (B, A)
4938 As above, these transformations don't work in the presence
4939 of signed zeros. For example, if A and B are zeros of
4940 opposite sign, the first two transformations will change
4941 the sign of the result. In the last four, the original
4942 expressions give different results for (A=+0, B=-0) and
4943 (A=-0, B=+0), but the transformed expressions do not.
4945 The first two transformations are correct if either A or B
4946 is a NaN. In the first transformation, the condition will
4947 be false, and B will indeed be chosen. In the case of the
4948 second transformation, the condition A != B will be true,
4949 and A will be chosen.
4951 The conversions to max() and min() are not correct if B is
4952 a number and A is not. The conditions in the original
4953 expressions will be false, so all four give B. The min()
4954 and max() versions would give a NaN instead. */
4957 /* Avoid these transformations if the COND_EXPR may be used
4958 as an lvalue in the C++ front-end. PR c++/19199. */
4959 && (in_gimple_form
4965 {
4970 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4972 {
4976 }
4979 {
4988 /* In C++ a ?: expression can be an lvalue, so put the
4989 operand which will be used if they are equal first
4990 so that we can convert this back to the
4991 corresponding COND_EXPR. */
4993 {
5002 }
5009 {
5018 }
5033 }
5034 }
5036 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5037 we might still be able to simplify this. For example,
5038 if C1 is one less or one more than C2, this might have started
5039 out as a MIN or MAX and been transformed by this function.
5040 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5046 {
5050 /* We can replace A with C1 in this case. */
5055 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5056 MIN_EXPR, to preserve the signedness of the comparison. */
5058 OEP_ONLY_CONST)
5062 OEP_ONLY_CONST))
5063 {
5066 arg2));
5069 }
5073 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5074 as above. */
5076 OEP_ONLY_CONST)
5080 OEP_ONLY_CONST))
5081 {
5084 arg2));
5087 }
5091 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5092 MAX_EXPR, to preserve the signedness of the comparison. */
5094 OEP_ONLY_CONST)
5098 OEP_ONLY_CONST))
5099 {
5102 arg2));
5104 }
5108 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5110 OEP_ONLY_CONST)
5114 OEP_ONLY_CONST))
5115 {
5118 arg2));
5120 }
5126 }
5129 }
5132 \f
5133 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5134 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5135 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5136 false) >= 2)
5137 #endif
5139 /* EXP is some logical combination of boolean tests. See if we can
5140 merge it into some range test. Return the new tree if so. */
5142 static tree
5145 {
5161 /* If this is an OR operation, invert both sides; we will invert
5162 again at the end. */
5166 /* If both expressions are the same, if we can merge the ranges, and we
5167 can build the range test, return it or it inverted. If one of the
5168 ranges is always true or always false, consider it to be the same
5169 expression as the other. */
5177 {
5181 }
5183 /* On machines where the branch cost is expensive, if this is a
5184 short-circuited branch and the underlying object on both sides
5185 is the same, make a non-short-circuit operation. */
5191 {
5192 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5193 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5194 which cases we can't do this. */
5202 {
5211 {
5214 WARN_STRICT_OVERFLOW_COMPARISON);
5218 }
5219 }
5220 }
5223 }
5224 \f
5225 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5226 bit value. Arrange things so the extra bits will be set to zero if and
5227 only if C is signed-extended to its full width. If MASK is nonzero,
5228 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5230 static tree
5232 {
5235 tree temp;
5240 /* We work by getting just the sign bit into the low-order bit, then
5241 into the high-order bit, then sign-extend. We then XOR that value
5242 with C. */
5245 /* We must use a signed type in order to get an arithmetic right shift.
5246 However, we must also avoid introducing accidental overflows, so that
5247 a subsequent call to integer_zerop will work. Hence we must
5248 do the type conversion here. At this point, the constant is either
5249 zero or one, and the conversion to a signed type can never overflow.
5250 We could get an overflow if this conversion is done anywhere else. */
5259 /* If necessary, convert the type back to match the type of C. */
5264 }
5265 \f
5266 /* For an expression that has the form
5267 (A && B) || ~B
5268 or
5269 (A || B) && ~B,
5270 we can drop one of the inner expressions and simplify to
5271 A || ~B
5272 or
5273 A && ~B
5274 LOC is the location of the resulting expression. OP is the inner
5275 logical operation; the left-hand side in the examples above, while CMPOP
5276 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5277 removing a condition that guards another, as in
5278 (A != NULL && A->...) || A == NULL
5279 which we must not transform. If RHS_ONLY is true, only eliminate the
5280 right-most operand of the inner logical operation. */
5282 static tree
5285 {
5303 {
5306 {
5309 }
5310 }
5312 {
5315 {
5318 }
5319 }
5334 }
5336 /* Find ways of folding logical expressions of LHS and RHS:
5337 Try to merge two comparisons to the same innermost item.
5338 Look for range tests like "ch >= '0' && ch <= '9'".
5339 Look for combinations of simple terms on machines with expensive branches
5340 and evaluate the RHS unconditionally.
5342 For example, if we have p->a == 2 && p->b == 4 and we can make an
5343 object large enough to span both A and B, we can do this with a comparison
5344 against the object ANDed with the a mask.
5346 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5347 operations to do this with one comparison.
5349 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5350 function and the one above.
5352 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5353 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5355 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5356 two operands.
5358 We return the simplified tree or 0 if no optimization is possible. */
5360 static tree
5363 {
5364 /* If this is the "or" of two comparisons, we can do something if
5365 the comparisons are NE_EXPR. If this is the "and", we can do something
5366 if the comparisons are EQ_EXPR. I.e.,
5367 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5369 WANTED_CODE is this operation code. For single bit fields, we can
5370 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5371 comparison for one-bit fields. */
5391 /* Start by getting the comparison codes. Fail if anything is volatile.
5392 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5393 it were surrounded with a NE_EXPR. */
5402 {
5406 }
5409 {
5413 }
5424 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5427 {
5430 {
5435 }
5438 {
5444 }
5445 }
5450 /* If the RHS can be evaluated unconditionally and its operands are
5451 simple, it wins to evaluate the RHS unconditionally on machines
5452 with expensive branches. In this case, this isn't a comparison
5453 that can be merged. */
5460 {
5461 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5472 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5482 }
5484 /* See if the comparisons can be merged. Then get all the parameters for
5485 each side. */
5509 /* It must be true that the inner operation on the lhs of each
5510 comparison must be the same if we are to be able to do anything.
5511 Then see if we have constants. If not, the same must be true for
5512 the rhs's. */
5523 else
5526 /* If either comparison code is not correct for our logical operation,
5527 fail. However, we can convert a one-bit comparison against zero into
5528 the opposite comparison against that bit being set in the field. */
5532 {
5534 {
5535 /* Make the left operand unsigned, since we are only interested
5536 in the value of one bit. Otherwise we are doing the wrong
5537 thing below. */
5540 }
5541 else
5543 }
5545 /* This is analogous to the code for l_const above. */
5547 {
5549 {
5552 }
5553 else
5555 }
5557 /* See if we can find a mode that contains both fields being compared on
5558 the left. If we can't, fail. Otherwise, update all constants and masks
5559 to be relative to a field of that size. */
5564 volatilep);
5574 {
5577 }
5585 {
5592 {
5596 }
5597 }
5599 {
5606 {
5610 }
5611 }
5613 /* If the right sides are not constant, do the same for it. Also,
5614 disallow this optimization if a size or signedness mismatch occurs
5615 between the left and right sides. */
5617 {
5620 /* Make sure the two fields on the right
5621 correspond to the left without being swapped. */
5629 volatilep);
5639 {
5642 }
5651 /* Make a mask that corresponds to both fields being compared.
5652 Do this for both items being compared. If the operands are the
5653 same size and the bits being compared are in the same position
5654 then we can do this by masking both and comparing the masked
5655 results. */
5659 {
5671 }
5673 /* There is still another way we can do something: If both pairs of
5674 fields being compared are adjacent, we may be able to make a wider
5675 field containing them both.
5677 Note that we still must mask the lhs/rhs expressions. Furthermore,
5678 the mask must be shifted to account for the shift done by
5679 make_bit_field_ref. */
5684 {
5685 tree type;
5699 /* Convert to the smaller type before masking out unwanted bits. */
5702 {
5704 {
5708 }
5710 {
5714 }
5715 }
5724 }
5727 }
5729 /* Handle the case of comparisons with constants. If there is something in
5730 common between the masks, those bits of the constants must be the same.
5731 If not, the condition is always false. Test for this to avoid generating
5732 incorrect code below. */
5737 {
5739 {
5742 }
5743 else
5744 {
5747 }
5748 }
5750 /* Construct the expression we will return. First get the component
5751 reference we will make. Unless the mask is all ones the width of
5752 that field, perform the mask operation. Then compare with the
5753 merged constant. */
5763 }
5764 \f
5765 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5766 constant. */
5768 static tree
5771 {
5774 tree comp_const;
5775 tree minmax_const;
5777 tree inner;
5788 /* If something does not permit us to optimize, return the original tree. */
5796 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5797 and GT_EXPR, doing the rest with recursive calls using logical
5798 simplifications. */
5800 {
5802 {
5803 tree tem
5810 }
5813 return
5815 optimize_minmax_comparison
5817 optimize_minmax_comparison
5822 /* MAX (X, 0) == 0 -> X <= 0 */
5826 /* MAX (X, 0) == 5 -> X == 5 */
5830 /* MAX (X, 0) == -1 -> false */
5834 /* MIN (X, 0) == 0 -> X >= 0 */
5838 /* MIN (X, 0) == 5 -> false */
5841 else
5842 /* MIN (X, 0) == -1 -> X == -1 */
5847 /* MAX (X, 0) > 0 -> X > 0
5848 MAX (X, 0) > 5 -> X > 5 */
5852 /* MAX (X, 0) > -1 -> true */
5856 /* MIN (X, 0) > 0 -> false
5857 MIN (X, 0) > 5 -> false */
5860 else
5861 /* MIN (X, 0) > -1 -> X > -1 */
5866 }
5867 }
5868 \f
5869 /* T is an integer expression that is being multiplied, divided, or taken a
5870 modulus (CODE says which and what kind of divide or modulus) by a
5871 constant C. See if we can eliminate that operation by folding it with
5872 other operations already in T. WIDE_TYPE, if non-null, is a type that
5873 should be used for the computation if wider than our type.
5875 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5876 (X * 2) + (Y * 4). We must, however, be assured that either the original
5877 expression would not overflow or that overflow is undefined for the type
5878 in the language in question.
5880 If we return a non-null expression, it is an equivalent form of the
5881 original computation, but need not be in the original type.
5883 We set *STRICT_OVERFLOW_P to true if the return values depends on
5884 signed overflow being undefined. Otherwise we do not change
5885 *STRICT_OVERFLOW_P. */
5887 static tree
5890 {
5891 /* To avoid exponential search depth, refuse to allow recursion past
5892 three levels. Beyond that (1) it's highly unlikely that we'll find
5893 something interesting and (2) we've probably processed it before
5894 when we built the inner expression. */
5897 tree ret;
5902 depth++;
5904 depth--;
5907 }
5909 static tree
5912 {
5923 /* Don't deal with constants of zero here; they confuse the code below. */
5933 /* Note that we need not handle conditional operations here since fold
5934 already handles those cases. So just do arithmetic here. */
5936 {
5938 /* For a constant, we can always simplify if we are a multiply
5939 or (for divide and modulus) if it is a multiple of our constant. */
5947 /* If op0 is an expression ... */
5953 /* ... and has wrapping overflow, and its type is smaller
5954 than ctype, then we cannot pass through as widening. */
5959 /* ... or this is a truncation (t is narrower than op0),
5960 then we cannot pass through this narrowing. */
5963 /* ... or signedness changes for division or modulus,
5964 then we cannot pass through this conversion. */
5968 /* ... or has undefined overflow while the converted to
5969 type has not, we cannot do the operation in the inner type
5970 as that would introduce undefined overflow. */
5976 /* Pass the constant down and see if we can make a simplification. If
5977 we can, replace this expression with the inner simplification for
5978 possible later conversion to our or some other type. */
5983 code == MULT_EXPR
5985 strict_overflow_p))))
5990 /* If widening the type changes it from signed to unsigned, then we
5991 must avoid building ABS_EXPR itself as unsigned. */
5993 {
5997 {
6000 }
6002 }
6003 /* If the constant is negative, we cannot simplify this. */
6006 /* FALLTHROUGH */
6008 /* For division and modulus, type can't be unsigned, as e.g.
6009 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6010 For signed types, even with wrapping overflow, this is fine. */
6019 /* If widening the type changes the signedness, then we can't perform
6020 this optimization as that changes the result. */
6024 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6030 {
6037 }
6041 /* If the second operand is constant, this is a multiplication
6042 or floor division, by a power of two, so we can treat it that
6043 way unless the multiplier or divisor overflows. Signed
6044 left-shift overflow is implementation-defined rather than
6045 undefined in C90, so do not convert signed left shift into
6046 multiplication. */
6049 /* const_binop may not detect overflow correctly,
6050 so check for it explicitly here. */
6054 size_one_node,
6055 op1)))
6059 ctype,
6061 t1),
6066 /* See if we can eliminate the operation on both sides. If we can, we
6067 can return a new PLUS or MINUS. If we can't, the only remaining
6068 cases where we can do anything are if the second operand is a
6069 constant. */
6075 /* If not multiplication, we can only do this if both operands
6076 are divisible by c. */
6079 {
6084 }
6086 /* If this was a subtraction, negate OP1 and set it to be an addition.
6087 This simplifies the logic below. */
6089 {
6091 /* If OP1 was not easily negatable, the constant may be OP0. */
6093 {
6100 }
6101 }
6106 /* If either OP1 or C are negative, this optimization is not safe for
6107 some of the division and remainder types while for others we need
6108 to change the code. */
6110 {
6118 }
6120 /* If it's a multiply or a division/modulus operation of a multiple
6121 of our constant, do the operation and verify it doesn't overflow. */
6124 {
6127 /* We allow the constant to overflow with wrapping semantics. */
6131 }
6132 else
6135 /* If we have an unsigned type, we cannot widen the operation since it
6136 will change the result if the original computation overflowed. */
6140 /* If we were able to eliminate our operation from the first side,
6141 apply our operation to the second side and reform the PLUS. */
6145 /* The last case is if we are a multiply. In that case, we can
6146 apply the distributive law to commute the multiply and addition
6147 if the multiplication of the constants doesn't overflow
6148 and overflow is defined. With undefined overflow
6149 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6155 op1);
6160 /* We have a special case here if we are doing something like
6161 (C * 8) % 4 since we know that's zero. */
6164 /* If the multiplication can overflow we cannot optimize this. */
6168 {
6171 }
6173 /* ... fall through ... */
6177 /* If we can extract our operation from the LHS, do so and return a
6178 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6179 do something only if the second operand is a constant. */
6193 /* If these are the same operation types, we can associate them
6194 assuming no overflow. */
6196 {
6208 }
6210 /* If these operations "cancel" each other, we have the main
6211 optimizations of this pass, which occur when either constant is a
6212 multiple of the other, in which case we replace this with either an
6213 operation or CODE or TCODE.
6215 If we have an unsigned type, we cannot do this since it will change
6216 the result if the original computation overflowed. */
6223 {
6225 {
6232 }
6234 {
6241 }
6242 }
6247 }
6250 }
6251 \f
6252 /* Return a node which has the indicated constant VALUE (either 0 or
6253 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6254 and is of the indicated TYPE. */
6256 tree
6258 {
6267 else
6269 }
6272 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6273 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6274 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6275 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6276 COND is the first argument to CODE; otherwise (as in the example
6277 given here), it is the second argument. TYPE is the type of the
6278 original expression. Return NULL_TREE if no simplification is
6279 possible. */
6281 static tree
6286 {
6296 {
6300 /* If this operand throws an expression, then it does not make
6301 sense to try to perform a logical or arithmetic operation
6302 involving it. */
6307 }
6308 else
6309 {
6314 }
6319 /* This transformation is only worthwhile if we don't have to wrap ARG
6320 in a SAVE_EXPR and the operation can be simplified without recursing
6321 on at least one of the branches once its pushed inside the COND_EXPR. */
6330 {
6334 else
6336 }
6338 {
6342 else
6344 }
6346 /* Check that we have simplified at least one of the branches. */
6351 }
6353 \f
6354 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6356 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6357 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6358 ADDEND is the same as X.
6360 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6361 and finite. The problematic cases are when X is zero, and its mode
6362 has signed zeros. In the case of rounding towards -infinity,
6363 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6364 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6366 bool
6368 {
6372 /* Don't allow the fold with -fsignaling-nans. */
6376 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6380 /* In a vector or complex, we would need to check the sign of all zeros. */
6384 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6388 /* The mode has signed zeros, and we have to honor their sign.
6389 In this situation, there is only one case we can return true for.
6390 X - 0 is the same as X unless rounding towards -infinity is
6391 supported. */
6393 }
6395 /* Subroutine of fold() that checks comparisons of built-in math
6396 functions against real constants.
6398 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6399 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6400 is the type of the result and ARG0 and ARG1 are the operands of the
6401 comparison. ARG1 must be a TREE_REAL_CST.
6403 The function returns the constant folded tree if a simplification
6404 can be made, and NULL_TREE otherwise. */
6406 static tree
6410 {
6411 REAL_VALUE_TYPE c;
6414 {
6420 {
6421 /* sqrt(x) < y is always false, if y is negative. */
6425 /* sqrt(x) > y is always true, if y is negative and we
6426 don't care about NaNs, i.e. negative values of x. */
6430 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6433 }
6435 {
6436 REAL_VALUE_TYPE c2;
6442 {
6443 /* sqrt(x) > y is x == +Inf, when y is very large. */
6448 /* sqrt(x) > y is always false, when y is very large
6449 and we don't care about infinities. */
6451 }
6453 /* sqrt(x) > c is the same as x > c*c. */
6456 }
6458 {
6459 REAL_VALUE_TYPE c2;
6465 {
6466 /* sqrt(x) < y is always true, when y is a very large
6467 value and we don't care about NaNs or Infinities. */
6471 /* sqrt(x) < y is x != +Inf when y is very large and we
6472 don't care about NaNs. */
6477 /* sqrt(x) < y is x >= 0 when y is very large and we
6478 don't care about Infinities. */
6483 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6488 dconst0)),
6491 c2)));
6492 }
6494 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6499 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6504 dconst0)),
6507 c2)));
6508 }
6509 }
6512 }
6514 /* Subroutine of fold() that optimizes comparisons against Infinities,
6515 either +Inf or -Inf.
6517 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6518 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6519 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6521 The function returns the constant folded tree if a simplification
6522 can be made, and NULL_TREE otherwise. */
6524 static tree
6527 {
6528 machine_mode mode;
6529 REAL_VALUE_TYPE max;
6530 tree temp;
6535 /* For negative infinity swap the sense of the comparison. */
6541 {
6543 /* x > +Inf is always false, if with ignore sNANs. */
6549 /* x <= +Inf is always true, if we don't case about NaNs. */
6553 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6559 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6565 /* x < +Inf is always equal to x <= DBL_MAX. */
6571 /* x != +Inf is always equal to !(x > DBL_MAX). */
6583 }
6586 }
6588 /* Subroutine of fold() that optimizes comparisons of a division by
6589 a nonzero integer constant against an integer constant, i.e.
6590 X/C1 op C2.
6592 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6593 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6594 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6596 The function returns the constant folded tree if a simplification
6597 can be made, and NULL_TREE otherwise. */
6599 static tree
6602 {
6610 /* We have to do this the hard way to detect unsigned overflow.
6611 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6617 {
6622 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6626 }
6628 {
6632 {
6651 }
6652 }
6653 else
6654 {
6655 /* A negative divisor reverses the relational operators. */
6661 {
6680 }
6681 }
6684 {
6705 {
6708 }
6713 {
6716 }
6721 {
6724 }
6729 {
6732 }
6737 }
6740 }
6743 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6744 equality/inequality test, then return a simplified form of the test
6745 using a sign testing. Otherwise return NULL. TYPE is the desired
6746 result type. */
6748 static tree
6751 tree result_type)
6752 {
6753 /* If this is testing a single bit, we can optimize the test. */
6757 {
6758 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6759 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6763 /* This is only a win if casting to a signed type is cheap,
6764 i.e. when arg00's type is not a partial mode. */
6767 {
6770 result_type,
6773 }
6774 }
6777 }
6779 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6780 equality/inequality test, then return a simplified form of
6781 the test using shifts and logical operations. Otherwise return
6782 NULL. TYPE is the desired result type. */
6784 tree
6787 {
6788 /* If this is testing a single bit, we can optimize the test. */
6792 {
6801 /* First, see if we can fold the single bit test into a sign-bit
6802 test. */
6804 result_type);
6808 /* Otherwise we have (A & C) != 0 where C is a single bit,
6809 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6810 Similarly for (A & C) == 0. */
6812 /* If INNER is a right shift of a constant and it plus BITNUM does
6813 not overflow, adjust BITNUM and INNER. */
6819 {
6822 }
6824 /* If we are going to be able to omit the AND below, we must do our
6825 operations as unsigned. If we must use the AND, we have a choice.
6826 Normally unsigned is faster, but for some machines signed is. */
6827 #ifdef LOAD_EXTEND_OP
6830 #else
6832 #endif
6848 /* Put the AND last so it can combine with more things. */
6851 /* Make sure to return the proper type. */
6855 }
6857 }
6859 /* Check whether we are allowed to reorder operands arg0 and arg1,
6860 such that the evaluation of arg1 occurs before arg0. */
6862 static bool
6864 {
6871 }
6873 /* Test whether it is preferable two swap two operands, ARG0 and
6874 ARG1, for example because ARG0 is an integer constant and ARG1
6875 isn't. If REORDER is true, only recommend swapping if we can
6876 evaluate the operands in reverse order. */
6878 bool
6880 {
6898 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6899 for commutative and comparison operators. Ensuring a canonical
6900 form allows the optimizers to find additional redundancies without
6901 having to explicitly check for both orderings. */
6907 /* Put SSA_NAMEs last. */
6913 /* Put variables last. */
6920 }
6922 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6923 ARG0 is extended to a wider type. */
6925 static tree
6928 {
6930 tree arg1_unw;
6939 #ifdef HAVE_canonicalize_funcptr_for_compare
6940 /* Disable this optimization if we're casting a function pointer
6941 type on targets that require function pointer canonicalization. */
6946 #endif
6953 /* If possible, express the comparison in the shorter mode. */
6973 /* If we are comparing with the integer that does not fit into the range
6974 of the shorter type, the result is known. */
6985 {
7012 }
7015 }
7017 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7018 ARG0 just the signedness is changed. */
7020 static tree
7023 {
7024 tree arg0_inner;
7034 #ifdef HAVE_canonicalize_funcptr_for_compare
7035 /* Disable this optimization if we're casting a function pointer
7036 type on targets that require function pointer canonicalization. */
7041 #endif
7062 else
7066 }
7069 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7070 means A >= Y && A != MAX, but in this case we know that
7071 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7073 static tree
7075 {
7082 else
7091 {
7094 }
7096 {
7099 }
7100 else
7107 {
7108 /* Convert the pointer types into integer before taking the difference. */
7112 }
7113 else
7120 }
7122 /* Fold a sum or difference of at least one multiplication.
7123 Returns the folded tree or NULL if no simplification could be made. */
7125 static tree
7128 {
7132 /* (A * C) +- (B * C) -> (A+-B) * C.
7133 (A * C) +- A -> A * (C+-1).
7134 We are most concerned about the case where C is a constant,
7135 but other combinations show up during loop reduction. Since
7136 it is not difficult, try all four possibilities. */
7139 {
7142 }
7144 {
7147 }
7148 else
7149 {
7150 /* We cannot generate constant 1 for fract. */
7155 }
7157 {
7160 }
7162 {
7164 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7165 the purpose of this canonicalization. */
7169 {
7172 }
7173 else
7175 }
7176 else
7177 {
7178 /* We cannot generate constant 1 for fract. */
7183 }
7195 /* No identical multiplicands; see if we can find a common
7196 power-of-two factor in non-power-of-two multiplies. This
7197 can help in multi-dimensional array access. */
7200 {
7203 tree maybe_same;
7207 /* Move min of absolute values to int11. */
7209 {
7214 }
7215 else
7219 /* The remainder should not be a constant, otherwise we
7220 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7221 increased the number of multiplications necessary. */
7223 {
7231 }
7232 }
7242 }
7244 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7245 specified by EXPR into the buffer PTR of length LEN bytes.
7246 Return the number of bytes placed in the buffer, or zero
7247 upon failure. */
7249 static int
7251 {
7265 {
7267 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7268 number of bytes. */
7272 {
7279 else
7281 }
7282 else
7287 }
7289 }
7292 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7293 specified by EXPR into the buffer PTR of length LEN bytes.
7294 Return the number of bytes placed in the buffer, or zero
7295 upon failure. */
7297 static int
7299 {
7303 FIXED_VALUE_TYPE value;
7319 }
7322 /* Subroutine of native_encode_expr. Encode the REAL_CST
7323 specified by EXPR into the buffer PTR of length LEN bytes.
7324 Return the number of bytes placed in the buffer, or zero
7325 upon failure. */
7327 static int
7329 {
7335 /* There are always 32 bits in each long, no matter the size of
7336 the hosts long. We handle floating point representations with
7337 up to 192 bits. */
7351 {
7356 {
7363 else
7365 }
7366 else
7372 }
7374 }
7376 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7377 specified by EXPR into the buffer PTR of length LEN bytes.
7378 Return the number of bytes placed in the buffer, or zero
7379 upon failure. */
7381 static int
7383 {
7385 tree part;
7400 }
7403 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7404 specified by EXPR into the buffer PTR of length LEN bytes.
7405 Return the number of bytes placed in the buffer, or zero
7406 upon failure. */
7408 static int
7410 {
7420 {
7422 {
7425 }
7436 }
7438 }
7441 /* Subroutine of native_encode_expr. Encode the STRING_CST
7442 specified by EXPR into the buffer PTR of length LEN bytes.
7443 Return the number of bytes placed in the buffer, or zero
7444 upon failure. */
7446 static int
7448 {
7450 HOST_WIDE_INT total_bytes;
7464 {
7467 {
7470 }
7473 }
7474 else
7477 }
7480 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7481 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7482 buffer PTR of length LEN bytes. If OFF is not -1 then start
7483 the encoding at byte offset OFF and encode at most LEN bytes.
7484 Return the number of bytes placed in the buffer, or zero upon failure. */
7486 int
7488 {
7490 {
7511 }
7512 }
7515 /* Subroutine of native_interpret_expr. Interpret the contents of
7516 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7517 If the buffer cannot be interpreted, return NULL_TREE. */
7519 static tree
7521 {
7531 }
7534 /* Subroutine of native_interpret_expr. Interpret the contents of
7535 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7536 If the buffer cannot be interpreted, return NULL_TREE. */
7538 static tree
7540 {
7542 double_int result;
7543 FIXED_VALUE_TYPE fixed_value;
7553 }
7556 /* Subroutine of native_interpret_expr. Interpret the contents of
7557 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7558 If the buffer cannot be interpreted, return NULL_TREE. */
7560 static tree
7562 {
7567 /* There are always 32 bits in each long, no matter the size of
7568 the hosts long. We handle floating point representations with
7569 up to 192 bits. */
7570 REAL_VALUE_TYPE r;
7581 {
7584 {
7591 else
7593 }
7594 else
7599 }
7603 }
7606 /* Subroutine of native_interpret_expr. Interpret the contents of
7607 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7608 If the buffer cannot be interpreted, return NULL_TREE. */
7610 static tree
7612 {
7627 }
7630 /* Subroutine of native_interpret_expr. Interpret the contents of
7631 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7632 If the buffer cannot be interpreted, return NULL_TREE. */
7634 static tree
7636 {
7649 {
7654 }
7656 }
7659 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7660 the buffer PTR of length LEN as a constant of type TYPE. For
7661 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7662 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7663 return NULL_TREE. */
7665 tree
7667 {
7669 {
7691 }
7692 }
7694 /* Returns true if we can interpret the contents of a native encoding
7695 as TYPE. */
7697 static bool
7699 {
7701 {
7714 }
7715 }
7717 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7718 TYPE at compile-time. If we're unable to perform the conversion
7719 return NULL_TREE. */
7721 static tree
7723 {
7724 /* We support up to 512-bit values (for V8DFmode). */
7728 /* Check that the host and target are sane. */
7737 }
7739 /* Build an expression for the address of T. Folds away INDIRECT_REF
7740 to avoid confusing the gimplify process. */
7742 tree
7744 {
7745 /* The size of the object is not relevant when talking about its address. */
7750 {
7755 }
7765 {
7770 }
7771 else
7775 }
7777 /* Build an expression for the address of T. */
7779 tree
7781 {
7785 }
7787 /* Fold a unary expression of code CODE and type TYPE with operand
7788 OP0. Return the folded expression if folding is successful.
7789 Otherwise, return NULL_TREE. */
7791 tree
7793 {
7794 tree tem;
7795 tree arg0;
7803 {
7806 {
7807 /* Don't use STRIP_NOPS, because signedness of argument type
7808 matters. */
7810 }
7811 else
7812 {
7813 /* Strip any conversions that don't change the mode. This
7814 is safe for every expression, except for a comparison
7815 expression because its signedness is derived from its
7816 operands.
7818 Note that this is done as an internal manipulation within
7819 the constant folder, in order to find the simplest
7820 representation of the arguments so that their form can be
7821 studied. In any cases, the appropriate type conversions
7822 should be put back in the tree that will get out of the
7823 constant folder. */
7825 }
7828 {
7831 {
7835 }
7836 }
7837 }
7844 {
7851 {
7865 /* If this was a conversion, and all we did was to move into
7866 inside the COND_EXPR, bring it back out. But leave it if
7867 it is a conversion from integer to integer and the
7868 result precision is no wider than a word since such a
7869 conversion is cheap and may be optimized away by combine,
7870 while it couldn't if it were outside the COND_EXPR. Then return
7871 so we don't get into an infinite recursion loop taking the
7872 conversion out and then back in. */
7884 && (INTEGRAL_TYPE_P
7897 }
7898 }
7901 {
7907 CASE_CONVERT:
7911 {
7912 /* If we have (type) (a CMP b) and type is an integral type, return
7913 new expression involving the new type. Canonicalize
7914 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7915 non-integral type.
7916 Do not fold the result as that would not simplify further, also
7917 folding again results in recursions. */
7927 }
7929 /* Handle (T *)&A.B.C for A being of type T and B and C
7930 living at offset zero. This occurs frequently in
7931 C++ upcasting and then accessing the base. */
7935 {
7937 tree offset;
7938 machine_mode mode;
7943 /* If the reference was to a (constant) zero offset, we can use
7944 the address of the base if it has the same base type
7945 as the result type and the pointer type is unqualified. */
7952 }
7956 /* Detect assigning a bitfield. */
7958 && DECL_BIT_FIELD
7960 {
7961 /* Don't leave an assignment inside a conversion
7962 unless assigning a bitfield. */
7964 /* First do the assignment, then return converted constant. */
7969 }
7971 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7972 constants (if x has signed type, the sign bit cannot be set
7973 in c). This folds extension into the BIT_AND_EXPR.
7974 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7975 very likely don't have maximal range for their precision and this
7976 transformation effectively doesn't preserve non-maximal ranges. */
7980 {
7991 <= HOST_BITS_PER_WIDE_INT
7993 {
7997 cst &= HOST_WIDE_INT_M1U
8000 #ifdef LOAD_EXTEND_OP
8002 && !flag_syntax_only
8005 {
8009 }
8010 #endif
8011 }
8013 {
8018 }
8019 }
8021 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8022 when one of the new casts will fold away. Conservatively we assume
8023 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8030 {
8034 return fold_build_pointer_plus_loc
8036 }
8038 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8039 of the same precision, and X is an integer type not narrower than
8040 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8046 {
8052 }
8054 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8055 type of X and Y (integer types only). */
8060 {
8061 /* Be careful not to introduce new overflows. */
8062 tree mult_type;
8065 else
8069 {
8076 }
8077 }
8095 /* Convert fabs((double)float) into (double)fabsf(float). */
8098 {
8104 targ0));
8105 }
8106 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8110 /* Strip sign ops from argument. */
8112 {
8117 }
8124 {
8130 }
8136 /* Convert ~ (-A) to A - 1. */
8141 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8147 {
8148 /* Perform the negation in ARG0's type and only then convert
8149 to TYPE as to avoid introducing undefined behavior. */
8154 }
8155 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8174 /* Note that the operand of this must be an int
8175 and its values must be 0 or 1.
8176 ("true" is a fixed value perhaps depending on the language,
8177 but we don't handle values other than 1 correctly yet.) */
8187 {
8195 }
8197 {
8202 }
8204 {
8208 {
8217 }
8218 }
8225 {
8233 }
8235 {
8239 }
8241 {
8245 {
8254 }
8255 }
8259 /* Fold *&X to X if X is an lvalue. */
8261 {
8268 }
8274 }
8277 /* If the operation was a conversion do _not_ mark a resulting constant
8278 with TREE_OVERFLOW if the original constant was not. These conversions
8279 have implementation defined behavior and retaining the TREE_OVERFLOW
8280 flag here would confuse later passes such as VRP. */
8281 tree
8284 {
8293 }
8295 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8296 operands OP0 and OP1. LOC is the location of the resulting expression.
8297 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8298 Return the folded expression if folding is successful. Otherwise,
8299 return NULL_TREE. */
8300 static tree
8303 {
8304 tree tem;
8306 /* We only do these simplifications if we are optimizing. */
8310 /* Check for things like (A || B) && (A || C). We can convert this
8311 to A || (B && C). Note that either operator can be any of the four
8312 truth and/or operations and the transformation will still be
8313 valid. Also note that we only care about order for the
8314 ANDIF and ORIF operators. If B contains side effects, this
8315 might change the truth-value of A. */
8322 {
8342 /* This case if tricky because we must either have commutative
8343 operators or else A10 must not have side-effects. */
8349 a01);
8350 }
8352 /* See if we can build a range comparison. */
8358 {
8362 }
8366 {
8370 }
8372 /* Check for the possibility of merging component references. If our
8373 lhs is another similar operation, try to merge its rhs with our
8374 rhs. Then try to merge our lhs and rhs. */
8388 {
8395 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8396 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8397 We don't want to pack more than two leafs to a non-IF AND/OR
8398 expression.
8399 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8400 equal to IF-CODE, then we don't want to add right-hand operand.
8401 If the inner right-hand side of left-hand operand has
8402 side-effects, or isn't simple, then we can't add to it,
8403 as otherwise we might destroy if-sequence. */
8406 /* Needed for sequence points to handle trappings, and
8407 side-effects. */
8409 {
8411 arg1);
8413 tem);
8414 }
8415 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8416 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8419 /* Needed for sequence points to handle trappings, and
8420 side-effects. */
8422 {
8427 }
8428 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8429 into (A OR B).
8430 For sequence point consistancy, we need to check for trapping,
8431 and side-effects. */
8435 }
8438 }
8440 /* Fold a binary expression of code CODE and type TYPE with operands
8441 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8442 Return the folded expression if folding is successful. Otherwise,
8443 return NULL_TREE. */
8445 static tree
8447 {
8454 else
8457 /* MIN (MAX (a, b), b) == b. */
8462 /* MIN (MAX (b, a), b) == b. */
8468 /* MIN (a, MAX (a, b)) == a. */
8474 /* MIN (a, MAX (b, a)) == a. */
8481 }
8483 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8484 by changing CODE to reduce the magnitude of constants involved in
8485 ARG0 of the comparison.
8486 Returns a canonicalized comparison tree if a simplification was
8487 possible, otherwise returns NULL_TREE.
8488 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8489 valid if signed overflow is undefined. */
8491 static tree
8495 {
8501 /* Match A +- CST code arg1 and CST code arg1. We can change the
8502 first form only if overflow is undefined. */
8505 /* In principle pointers also have undefined overflow behavior,
8506 but that causes problems elsewhere. */
8514 /* Identify the constant in arg0 and its sign. */
8517 else
8521 /* Overflowed constants and zero will cause problems. */
8526 /* See if we can reduce the magnitude of the constant in
8527 arg0 by changing the comparison code. */
8529 {
8530 /* CST <= arg1 -> CST-1 < arg1. */
8533 /* -CST < arg1 -> -CST-1 <= arg1. */
8536 /* CST > arg1 -> CST-1 >= arg1. */
8539 /* -CST >= arg1 -> -CST-1 > arg1. */
8542 else
8544 /* arg1 code' CST' might be more canonical. */
8546 }
8547 else
8548 {
8549 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8553 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8557 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8561 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8565 else
8568 }
8570 /* Now build the constant reduced in magnitude. But not if that
8571 would produce one outside of its types range. */
8579 /* We cannot swap the comparison here as that would cause us to
8580 endlessly recurse. */
8589 /* If swapping might yield to a more canonical form, do so. */
8592 else
8594 }
8596 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8597 overflow further. Try to decrease the magnitude of constants involved
8598 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8599 and put sole constants at the second argument position.
8600 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8602 static tree
8605 {
8606 tree t;
8611 /* Try canonicalization by simplifying arg0. */
8616 {
8620 }
8622 /* Try canonicalization by simplifying arg1 using the swapped
8623 comparison. */
8631 }
8633 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8634 space. This is used to avoid issuing overflow warnings for
8635 expressions like &p->x which can not wrap. */
8637 static bool
8639 {
8646 wide_int wi_offset;
8652 else
8668 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8669 array. */
8671 {
8672 HOST_WIDE_INT base_size;
8677 }
8680 }
8682 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8683 kind INTEGER_CST. This makes sure to properly sign-extend the
8684 constant. */
8686 static HOST_WIDE_INT
8688 {
8694 }
8696 /* Subroutine of fold_binary. This routine performs all of the
8697 transformations that are common to the equality/inequality
8698 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8699 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8700 fold_binary should call fold_binary. Fold a comparison with
8701 tree code CODE and type TYPE with operands OP0 and OP1. Return
8702 the folded comparison or NULL_TREE. */
8704 static tree
8707 {
8717 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8719 && (equality_code
8726 {
8727 const enum tree_code
8734 /* If the constant operation overflowed this can be
8735 simplified as a comparison against INT_MAX/INT_MIN. */
8738 {
8742 /* Get the sign of the constant on the lhs if the
8743 operation were VARIABLE + CONST1. */
8747 /* The sign of the constant determines if we overflowed
8748 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8749 Canonicalize to the INT_MIN overflow by swapping the comparison
8750 if necessary. */
8754 /* We now can look at the canonicalized case
8755 VARIABLE + 1 CODE2 INT_MIN
8756 and decide on the result. */
8758 {
8762 return
8768 return
8773 }
8774 }
8775 else
8776 {
8779 "when changing X +- C1 cmp C2 to "
8781 WARN_STRICT_OVERFLOW_COMPARISON);
8783 }
8784 }
8786 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8788 && equality_code
8790 {
8791 /* ??? The transformation is valid for the other operators if overflow
8792 is undefined for the type, but performing it here badly interacts
8793 with the transformation in fold_cond_expr_with_comparison which
8794 attempts to synthetize ABS_EXPR. */
8798 WARN_STRICT_OVERFLOW_COMPARISON);
8801 }
8803 /* For comparisons of pointers we can decompose it to a compile time
8804 comparison of the base objects and the offsets into the object.
8805 This requires at least one operand being an ADDR_EXPR or a
8806 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8812 {
8815 machine_mode mode;
8819 /* Get base and offset for the access. Strip ADDR_EXPR for
8820 get_inner_reference, but put it back by stripping INDIRECT_REF
8821 off the base object if possible. indirect_baseN will be true
8822 if baseN is not an address but refers to the object itself. */
8825 {
8831 else
8833 }
8835 {
8839 {
8842 }
8845 {
8850 {
8853 }
8854 }
8855 }
8859 {
8865 else
8867 }
8869 {
8873 {
8876 }
8879 {
8884 {
8887 }
8888 }
8889 }
8891 /* A local variable can never be pointed to by
8892 the default SSA name of an incoming parameter. */
8894 && indirect_base0
8897 && !indirect_base1
8902 && indirect_base1
8905 && !indirect_base0
8909 {
8914 }
8915 /* If we have equivalent bases we might be able to simplify. */
8918 {
8919 /* We can fold this expression to a constant if the non-constant
8920 offset parts are equal. */
8929 {
8935 "occur when comparing P +- C1 with "
8937 WARN_STRICT_OVERFLOW_CONDITIONAL);
8940 {
8954 }
8955 }
8956 /* We can simplify the comparison to a comparison of the variable
8957 offset parts if the constant offset parts are equal.
8958 Be careful to use signed sizetype here because otherwise we
8959 mess with array offsets in the wrong way. This is possible
8960 because pointer arithmetic is restricted to retain within an
8961 object and overflow on pointer differences is undefined as of
8962 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8964 && (equality_code
8967 {
8968 /* By converting to signed sizetype we cover middle-end pointer
8969 arithmetic which operates on unsigned pointer types of size
8970 type size and ARRAY_REF offsets which are properly sign or
8971 zero extended from their type in case it is narrower than
8972 sizetype. */
8975 else
8979 else
8986 "occur when comparing P +- C1 with "
8988 WARN_STRICT_OVERFLOW_COMPARISON);
8991 }
8992 }
8993 /* For non-equal bases we can simplify if they are addresses
8994 declarations with different addresses. */
8996 /* We know that !operand_equal_p (base0, base1, 0)
8997 because the if condition was false. But make
8998 sure two decls are not the same. */
9004 /* Watch for aliases. */
9009 {
9016 }
9017 /* For equal offsets we can simplify to a comparison of the
9018 base addresses. */
9020 && (indirect_base0
9022 && (indirect_base1
9027 {
9033 }
9034 }
9036 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9037 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9038 the resulting offset is smaller in absolute value than the
9039 original one and has the same sign. */
9048 {
9053 tree cst;
9055 "occur when combining constants around "
9058 /* Put the constant on the side where it doesn't overflow and is
9059 of lower absolute value and of same sign than before. */
9066 {
9069 variable1,
9073 }
9081 {
9087 variable2);
9088 }
9089 }
9091 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9092 signed arithmetic case. That form is created by the compiler
9093 often enough for folding it to be of value. One example is in
9094 computing loop trip counts after Operator Strength Reduction. */
9101 {
9107 /* Handle unfolded multiplication by zero. */
9112 "eliminating multiplication in comparison "
9114 WARN_STRICT_OVERFLOW_COMPARISON);
9116 /* If const1 is negative we swap the sense of the comparison. */
9121 }
9128 {
9136 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9142 /* (-a) CMP (-b) -> b CMP a */
9149 {
9150 REAL_VALUE_TYPE cst;
9153 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9160 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9161 /* a CMP (-0) -> a CMP 0 */
9166 /* x != NaN is always true, other ops are always false. */
9169 {
9172 }
9174 /* Fold comparisons against infinity. */
9177 {
9181 }
9182 }
9184 /* If this is a comparison of a real constant with a PLUS_EXPR
9185 or a MINUS_EXPR of a real constant, we can convert it into a
9186 comparison with a revised real constant as long as no overflow
9187 occurs when unsafe_math_optimizations are enabled. */
9199 /* Likewise, we can simplify a comparison of a real constant with
9200 a MINUS_EXPR whose first operand is also a real constant, i.e.
9201 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9202 floating-point types only if -fassociative-math is set. */
9208 arg1))
9213 /* Fold comparisons against built-in math functions. */
9215 && flag_unsafe_math_optimizations
9217 {
9221 {
9225 }
9226 }
9227 }
9231 {
9232 /* If we are widening one operand of an integer comparison,
9233 see if the other operand is similarly being widened. Perhaps we
9234 can do the comparison in the narrower type. */
9239 /* Or if we are changing signedness. */
9243 }
9245 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9246 constant, we can simplify it. */
9251 {
9255 }
9257 /* Simplify comparison of something with itself. (For IEEE
9258 floating-point, we can only do some of these simplifications.) */
9260 {
9262 {
9277 /* For NE, we can only do this simplification if integer
9278 or we don't honor IEEE floating point NaNs. */
9282 /* ... fall through ... */
9288 }
9289 }
9291 /* If we are comparing an expression that just has comparisons
9292 of two integer values, arithmetic expressions of those comparisons,
9293 and constants, we can simplify it. There are only three cases
9294 to check: the two values can either be equal, the first can be
9295 greater, or the second can be greater. Fold the expression for
9296 those three values. Since each value must be 0 or 1, we have
9297 eight possibilities, each of which corresponds to the constant 0
9298 or 1 or one of the six possible comparisons.
9300 This handles common cases like (a > b) == 0 but also handles
9301 expressions like ((x > y) - (y > x)) > 0, which supposedly
9302 occur in macroized code. */
9305 {
9310 /* Don't handle degenerate cases here; they should already
9311 have been handled anyway. */
9320 {
9324 /* We can't just pass T to eval_subst in case cval1 or cval2
9325 was the same as ARG1. */
9327 tree high_result
9331 arg1);
9332 tree equal_result
9336 arg1);
9337 tree low_result
9341 arg1);
9343 /* All three of these results should be 0 or 1. Confirm they are.
9344 Then use those values to select the proper code to use. */
9349 {
9350 /* Make a 3-bit mask with the high-order bit being the
9351 value for `>', the next for '=', and the low for '<'. */
9355 {
9357 /* Always false. */
9378 /* Always true. */
9380 }
9383 {
9387 }
9389 }
9390 }
9391 }
9393 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9394 into a single range test. */
9402 {
9406 }
9408 /* Fold ~X op ~Y as Y op X. */
9411 {
9417 }
9419 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9422 {
9428 }
9431 }
9434 /* Subroutine of fold_binary. Optimize complex multiplications of the
9435 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9436 argument EXPR represents the expression "z" of type TYPE. */
9438 static tree
9440 {
9445 {
9448 }
9450 {
9453 }
9454 else
9455 {
9459 }
9468 }
9471 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9472 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9473 guarantees that P and N have the same least significant log2(M) bits.
9474 N is not otherwise constrained. In particular, N is not normalized to
9475 0 <= N < M as is common. In general, the precise value of P is unknown.
9476 M is chosen as large as possible such that constant N can be determined.
9478 Returns M and sets *RESIDUE to N.
9480 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9481 account. This is not always possible due to PR 35705.
9482 */
9484 static unsigned HOST_WIDE_INT
9487 {
9494 {
9499 }
9501 {
9509 allow_func_align);
9515 {
9518 }
9520 {
9523 {
9526 /* Compute the greatest power-of-2 divisor of op1. */
9530 /* If align is non-zero and less than *modulus, replace
9531 *modulus with align., If align is 0, then either op1 is 0
9532 or the greatest power-of-2 divisor of op1 doesn't fit in an
9533 unsigned HOST_WIDE_INT. In either case, no additional
9534 constraint is imposed. */
9539 }
9540 }
9541 }
9543 /* If we get here, we were unable to determine anything useful about the
9544 expression. */
9546 }
9548 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9549 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9551 static bool
9553 {
9557 {
9560 }
9562 {
9568 else
9570 }
9571 else
9577 }
9579 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9580 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9581 NULL_TREE otherwise. */
9583 static tree
9585 {
9602 {
9606 }
9609 {
9615 }
9616 else
9618 }
9620 /* Try to fold a pointer difference of type TYPE two address expressions of
9621 array references AREF0 and AREF1 using location LOC. Return a
9622 simplified expression for the difference or NULL_TREE. */
9624 static tree
9627 {
9632 /* If the bases are array references as well, recurse. If the bases
9633 are pointer indirections compute the difference of the pointers.
9634 If the bases are equal, we are set. */
9637 && (base_offset
9645 {
9651 base_offset,
9654 }
9656 }
9658 /* If the real or vector real constant CST of type TYPE has an exact
9659 inverse, return it, else return NULL. */
9661 tree
9663 {
9664 REAL_VALUE_TYPE r;
9666 machine_mode mode;
9670 {
9686 {
9691 }
9697 }
9698 }
9700 /* Mask out the tz least significant bits of X of type TYPE where
9701 tz is the number of trailing zeroes in Y. */
9702 static wide_int
9704 {
9709 }
9711 /* Return true when T is an address and is known to be nonzero.
9712 For floating point we further ensure that T is not denormal.
9713 Similar logic is present in nonzero_address in rtlanal.h.
9715 If the return value is based on the assumption that signed overflow
9716 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9717 change *STRICT_OVERFLOW_P. */
9719 static bool
9721 {
9725 /* Doing something useful for floating point would need more work. */
9731 {
9734 strict_overflow_p);
9740 strict_overflow_p);
9748 }
9751 {
9754 strict_overflow_p);
9762 strict_overflow_p);
9777 strict_overflow_p);
9781 strict_overflow_p);
9784 {
9796 }
9800 }
9802 }
9804 /* Return true when T is an address and is known to be nonzero.
9805 Handle warnings about undefined signed overflow. */
9807 static bool
9809 {
9816 "determining that expression is always "
9818 WARN_STRICT_OVERFLOW_MISC);
9820 }
9822 /* Fold a binary expression of code CODE and type TYPE with operands
9823 OP0 and OP1. LOC is the location of the resulting expression.
9824 Return the folded expression if folding is successful. Otherwise,
9825 return NULL_TREE. */
9827 tree
9830 {
9845 /* Strip any conversions that don't change the mode. This is
9846 safe for every expression, except for a comparison expression
9847 because its signedness is derived from its operands. So, in
9848 the latter case, only strip conversions that don't change the
9849 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9850 preserved.
9852 Note that this is done as an internal manipulation within the
9853 constant folder, in order to find the simplest representation
9854 of the arguments so that their form can be studied. In any
9855 cases, the appropriate type conversions should be put back in
9856 the tree that will get out of the constant folder. */
9859 {
9862 }
9863 else
9864 {
9867 }
9869 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9870 constant but we can't do arithmetic on them. */
9872 {
9875 {
9879 }
9880 }
9882 /* If this is a commutative operation, and ARG0 is a constant, move it
9883 to ARG1 to reduce the number of tests below. */
9888 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9889 to ARG1 to reduce the number of tests below. */
9898 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9900 First check for cases where an arithmetic operation is applied to a
9901 compound, conditional, or comparison operation. Push the arithmetic
9902 operation inside the compound or conditional to see if any folding
9903 can then be done. Convert comparison to conditional for this purpose.
9904 The also optimizes non-constant cases that used to be done in
9905 expand_expr.
9907 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9908 one of the operands is a comparison and the other is a comparison, a
9909 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9910 code below would make the expression more complex. Change it to a
9911 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9912 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9925 {
9929 boolean_type_node,
9937 }
9941 {
9943 {
9948 tem);
9949 }
9952 {
9957 tem);
9958 }
9963 {
9969 }
9974 {
9980 }
9981 }
9984 {
9986 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9989 {
9995 }
9997 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10000 {
10001 tree base;
10002 HOST_WIDE_INT coffset;
10011 }
10016 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10022 arg1),
10024 arg0)));
10030 {
10031 /* X + (X / CST) * -CST is X % CST. */
10036 {
10045 cst0));
10046 }
10047 }
10049 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10050 one. Make sure the type is not saturating and has the signedness of
10051 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10052 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10059 {
10063 }
10066 {
10067 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10068 with a constant, and the two constants have no bits in common,
10069 we should treat this as a BIT_IOR_EXPR since this may produce more
10070 simplifications. */
10077 {
10080 }
10082 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10083 (plus (plus (mult) (mult)) (foo)) so that we can
10084 take advantage of the factoring cases below. */
10093 {
10099 else
10112 parg0),
10114 marg)),
10118 return
10124 parg1)));
10125 }
10126 }
10127 else
10128 {
10129 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10130 to __complex__ ( x, y ). This is not the same for SNaNs or
10131 if signed zeros are involved. */
10135 {
10142 {
10146 {
10152 }
10154 {
10160 }
10161 }
10162 }
10170 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10171 We associate floats only if the user has specified
10172 -fassociative-math. */
10176 {
10181 {
10182 tree tree0;
10185 }
10186 }
10187 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10188 We associate floats only if the user has specified
10189 -fassociative-math. */
10193 {
10198 {
10199 tree tree0;
10202 }
10203 }
10204 }
10206 bit_rotate:
10207 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10208 is a rotate of A by C1 bits. */
10209 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10210 is a rotate of A by B bits. */
10211 {
10213 tree rtype;
10222 /* Only create rotates in complete modes. Other cases are not
10223 expanded properly. */
10226 {
10240 {
10246 }
10248 {
10256 element_precision
10260 return
10263 ? LROTATE_EXPR
10267 }
10269 {
10277 element_precision
10281 return fold_convert_loc
10284 ? LROTATE_EXPR
10288 }
10289 }
10290 }
10292 associate:
10293 /* In most languages, can't associate operations on floats through
10294 parentheses. Rather than remember where the parentheses were, we
10295 don't associate floats at all, unless the user has specified
10296 -fassociative-math.
10297 And, we need to make sure type is not saturating. */
10301 {
10307 /* Split both trees into variables, constants, and literals. Then
10308 associate each group together, the constants with literals,
10309 then the result with variables. This increases the chances of
10310 literals being recombined later and of generating relocatable
10311 expressions for the sum of a constant and literal. */
10316 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10320 /* With undefined overflow prefer doing association in a type
10321 which wraps on overflow, if that is one of the operand types. */
10324 {
10332 }
10334 /* With undefined overflow we can only associate constants with one
10335 variable, and constants whose association doesn't overflow. */
10338 {
10340 {
10358 /* The only case we can still associate with two variables
10359 is if they are the same, modulo negation and bit-pattern
10360 preserving conversions. */
10363 }
10364 }
10366 /* Only do something if we found more than two objects. Otherwise,
10367 nothing has changed and we risk infinite recursion. */
10373 {
10385 /* Preserve the MINUS_EXPR if the negative part of the literal is
10386 greater than the positive part. Otherwise, the multiplicative
10387 folding code (i.e extract_muldiv) may be fooled in case
10388 unsigned constants are subtracted, like in the following
10389 example: ((X*2 + 4) - 8U)/2. */
10391 {
10395 {
10399 }
10400 else
10401 {
10405 }
10406 }
10408 /* Don't introduce overflows through reassociation. */
10415 {
10417 return
10421 else
10422 {
10425 return
10429 }
10430 }
10433 return
10436 }
10437 }
10442 /* Pointer simplifications for subtraction, simple reassociations. */
10444 {
10445 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10448 {
10458 }
10459 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10461 {
10468 }
10469 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10470 simplifies. */
10472 {
10479 arg10);
10482 }
10483 }
10484 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10494 /* X - (X / Y) * Y is X % Y. */
10502 return
10508 {
10509 /* Fold A - (A & B) into ~B & A. */
10512 {
10514 {
10521 }
10523 {
10530 }
10531 }
10533 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10534 any power of 2 minus 1. */
10539 {
10545 {
10549 }
10550 }
10551 }
10553 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10554 __complex__ ( x, -y ). This is not the same for SNaNs or if
10555 signed zeros are involved. */
10559 {
10566 {
10570 {
10572 arg1r ? arg1r
10577 }
10579 {
10583 arg1i ? arg1i
10586 }
10587 }
10588 }
10590 /* A - B -> A + (-B) if B is easily negatable. */
10594 /* Avoid this transformation if B is a positive REAL_CST. */
10603 /* Try folding difference of addresses. */
10604 {
10605 HOST_WIDE_INT diff;
10611 }
10613 /* Fold &a[i] - &a[j] to i-j. */
10618 {
10624 }
10627 && flag_unsafe_math_optimizations
10633 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10634 one. Make sure the type is not saturating and has the signedness of
10635 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10636 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10643 {
10647 }
10652 /* (-A) * (-B) -> A * B */
10667 {
10668 /* Transform x * -C into -x * C if x is easily negatable. */
10677 tem);
10679 /* (a * (1 << b)) is (a << b) */
10689 /* (A + A) * C -> A * 2 * C */
10701 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10702 sign-changing only. */
10712 {
10715 "occur when simplifying "
10717 WARN_STRICT_OVERFLOW_MISC);
10719 }
10721 /* Optimize z * conj(z) for integer complex numbers. */
10728 }
10729 else
10730 {
10731 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10732 the result for floating point types due to rounding so it is applied
10733 only if -fassociative-math was specify. */
10738 {
10740 arg1);
10744 }
10746 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10748 {
10751 {
10754 }
10755 }
10757 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10758 This is not the same for NaNs or if signed zeros are
10759 involved. */
10765 {
10768 return
10774 return
10779 }
10781 /* Optimize z * conj(z) for floating point complex numbers.
10782 Guarded by flag_unsafe_math_optimizations as non-finite
10783 imaginary components don't produce scalar results. */
10794 {
10798 /* Optimizations of root(...)*root(...). */
10800 {
10805 /* Optimize sqrt(x)*sqrt(x) as x. */
10811 /* Optimize root(x)*root(y) as root(x*y). */
10815 }
10817 /* Optimize expN(x)*expN(y) as expN(x+y). */
10819 {
10825 }
10827 /* Optimizations of pow(...)*pow(...). */
10831 {
10837 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10839 {
10844 }
10846 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10848 {
10853 }
10854 }
10856 /* Optimize tan(x)*cos(x) as sin(x). */
10865 {
10871 }
10873 /* Optimize x*pow(x,c) as pow(x,c+1). */
10877 {
10883 {
10885 REAL_VALUE_TYPE c;
10886 tree arg;
10892 }
10893 }
10895 /* Optimize pow(x,c)*x as pow(x,c+1). */
10899 {
10905 {
10907 REAL_VALUE_TYPE c;
10908 tree arg;
10914 }
10915 }
10917 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10919 && optimize
10921 {
10925 {
10928 }
10929 }
10930 }
10931 }
10935 bit_ior:
10936 /* ~X | X is -1. */
10939 {
10943 }
10945 /* X | ~X is -1. */
10948 {
10952 }
10954 /* Canonicalize (X & C1) | C2. */
10958 {
10963 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10971 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10976 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10977 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10978 mode which allows further optimizations. */
10983 {
10987 {
10990 }
10991 }
10998 c3)),
10999 arg1);
11000 }
11002 /* (X & ~Y) | (~X & Y) is X ^ Y */
11005 {
11022 }
11028 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11030 This results in more efficient code for machines without a NAND
11031 instruction. Combine will canonicalize to the first form
11032 which will allow use of NAND instructions provided by the
11033 backend if they exist. */
11036 {
11037 return
11044 }
11046 /* See if this can be simplified into a rotate first. If that
11047 is unsuccessful continue in the association code. */
11051 /* ~X ^ X is -1. */
11054 {
11058 }
11060 /* X ^ ~X is -1. */
11063 {
11067 }
11069 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11070 with a constant, and the two constants have no bits in common,
11071 we should treat this as a BIT_IOR_EXPR since this may produce more
11072 simplifications. */
11079 {
11082 }
11084 /* (X | Y) ^ X -> Y & ~ X*/
11087 {
11090 arg1);
11095 }
11097 /* (Y | X) ^ X -> Y & ~ X*/
11100 {
11103 arg1);
11108 }
11110 /* X ^ (X | Y) -> Y & ~ X*/
11113 {
11116 arg0);
11121 }
11123 /* X ^ (Y | X) -> Y & ~ X*/
11126 {
11129 arg0);
11134 }
11136 /* Convert ~X ^ ~Y to X ^ Y. */
11145 /* Convert ~X ^ C to X ^ ~C. */
11153 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11161 /* Fold (X & Y) ^ Y as ~X & Y. */
11164 {
11169 }
11170 /* Fold (X & Y) ^ X as ~Y & X. */
11174 {
11179 }
11180 /* Fold X ^ (X & Y) as X & ~Y. */
11183 {
11188 }
11189 /* Fold X ^ (Y & X) as ~Y & X. */
11193 {
11198 }
11200 /* See if this can be simplified into a rotate first. If that
11201 is unsuccessful continue in the association code. */
11205 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11213 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11221 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11226 {
11227 tree tem2;
11234 }
11235 /* Fold ~X & 1 as (X & 1) == 0. */
11239 {
11240 tree tem2;
11247 }
11248 /* Fold !X & 1 as X == 0. */
11251 {
11255 }
11257 /* Fold (X ^ Y) & Y as ~X & Y. */
11260 {
11265 }
11266 /* Fold (X ^ Y) & X as ~Y & X. */
11270 {
11275 }
11276 /* Fold X & (X ^ Y) as X & ~Y. */
11279 {
11284 }
11285 /* Fold X & (Y ^ X) as ~Y & X. */
11289 {
11294 }
11296 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11297 multiple of 1 << CST. */
11299 {
11306 }
11308 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11309 bits from CST2. */
11313 {
11321 {
11322 /* Avoid the transform if arg1 is a mask of some
11323 mode which allows further optimizations. */
11330 }
11331 }
11333 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11334 ((A & N) + B) & M -> (A + B) & M
11335 Similarly if (N & M) == 0,
11336 ((A | N) + B) & M -> (A + B) & M
11337 and for - instead of + (or unary - instead of +)
11338 and/or ^ instead of |.
11339 If B is constant and (B & M) == 0, fold into A & M. */
11341 {
11350 {
11353 wide_int cst0;
11355 /* Now we know that arg0 is (C + D) or (C - D) or
11356 -C and arg1 (M) is == (1LL << cst) - 1.
11357 Store C into PMOP[0] and D into PMOP[1]. */
11361 {
11364 }
11371 {
11381 {
11384 }
11387 /* If C or D is of the form (A & N) where
11388 (N & M) == M, or of the form (A | N) or
11389 (A ^ N) where (N & M) == 0, replace it with A. */
11393 /* If C or D is a N where (N & M) == 0, it can be
11394 omitted (assumed 0). */
11402 }
11404 /* Only build anything new if we optimized one or both arguments
11405 above. */
11409 {
11412 {
11413 /* Perform the operations in a type that has defined
11414 overflow behavior. */
11420 }
11425 {
11433 else
11435 }
11438 else
11441 /* TEM is now the new binary +, - or unary - replacement. */
11445 }
11446 }
11447 }
11452 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11455 {
11460 return
11462 }
11464 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11466 This results in more efficient code for machines without a NOR
11467 instruction. Combine will canonicalize to the first form
11468 which will allow use of NOR instructions provided by the
11469 backend if they exist. */
11472 {
11479 }
11481 /* If arg0 is derived from the address of an object or function, we may
11482 be able to fold this expression using the object or function's
11483 alignment. */
11485 {
11492 /* This works because modulus is a power of 2. If this weren't the
11493 case, we'd have to replace it by its greatest power-of-2
11494 divisor: modulus & -modulus. */
11497 }
11499 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11500 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11501 if the new mask might be further optimized. */
11510 {
11521 {
11524 /* See if more bits can be proven as zero because of
11525 zero extension. */
11528 {
11533 {
11535 /* See if we can shorten the right shift. */
11538 /* Otherwise X >> C1 is all zeros, so we'll optimize
11539 it into (X, 0) later on by making sure zerobits
11540 is all ones. */
11541 }
11542 }
11545 {
11548 }
11549 /* For arithmetic shift if sign bit could be set, zerobits
11550 can contain actually sign bits, so no transformation is
11551 possible, unless MASK masks them all away. In that
11552 case the shift needs to be converted into logical shift. */
11555 {
11558 else
11560 }
11561 }
11563 /* ((X << 16) & 0xff00) is (X, 0). */
11570 {
11571 /* Only do the transformation if NEWMASK is some integer
11572 mode's mask. */
11579 {
11580 tree newmaskt;
11583 {
11589 }
11590 else
11595 }
11596 }
11597 }
11602 /* Don't touch a floating-point divide by zero unless the mode
11603 of the constant can represent infinity. */
11609 /* (-A) / (-B) -> A / B */
11619 /* Convert A/B/C to A/(B*C). */
11626 /* Convert A/(B/C) to (A/B)*C. */
11634 /* Convert C1/(X*C2) into (C1/C2)/X. */
11639 {
11645 }
11648 {
11652 /* Optimize sin(x)/cos(x) as tan(x). */
11658 {
11663 }
11665 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11671 {
11675 {
11680 }
11681 }
11683 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11684 NaNs or Infinities. */
11688 {
11695 {
11700 }
11701 }
11703 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11704 NaNs or Infinities. */
11708 {
11715 {
11719 {
11723 tmp);
11724 }
11725 }
11726 }
11728 /* Optimize pow(x,c)/x as pow(x,c-1). */
11732 {
11738 {
11740 REAL_VALUE_TYPE c;
11741 tree arg;
11747 }
11748 }
11750 /* Optimize a/root(b/c) into a*root(c/b). */
11752 {
11756 {
11765 }
11766 }
11768 /* Optimize x/expN(y) into x*expN(-y). */
11770 {
11777 }
11779 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11783 {
11791 }
11792 }
11796 /* Optimize (X & (-A)) / A where A is a power of 2,
11797 to X >> log2(A) */
11801 {
11809 }
11810 }
11812 /* Fall through */
11815 /* Simplify A / (B << N) where A and B are positive and B is
11816 a power of 2, to A >> (N + log2(B)). */
11821 {
11824 {
11832 WARN_STRICT_OVERFLOW_MISC);
11838 }
11839 }
11841 /* Fall through */
11849 /* Convert -A / -B to A / B when the type is signed and overflow is
11850 undefined. */
11854 {
11857 "when distributing negation across "
11859 WARN_STRICT_OVERFLOW_MISC);
11865 }
11869 {
11872 "when distributing negation across "
11874 WARN_STRICT_OVERFLOW_MISC);
11880 }
11882 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11883 operation, EXACT_DIV_EXPR.
11885 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11886 At one time others generated faster code, it's not clear if they do
11887 after the last round to changes to the DIV code in expmed.c. */
11896 {
11900 WARN_STRICT_OVERFLOW_MISC);
11902 }
11910 /* X % -Y is the same as X % Y. */
11923 {
11927 WARN_STRICT_OVERFLOW_MISC);
11929 }
11931 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11932 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11936 {
11938 /* Also optimize A % (C << N) where C is a power of 2,
11939 to A & ((C << N) - 1). */
11944 {
11945 tree mask
11950 "occur when simplifying "
11952 WARN_STRICT_OVERFLOW_MISC);
11956 }
11957 }
11965 /* Since negative shift count is not well-defined,
11966 don't try to compute it in the compiler. */
11972 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11977 {
11981 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11982 being well defined. */
11984 {
11990 else
11992 }
11996 }
11998 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11999 into x & ((unsigned)-1 >> c) for unsigned types. */
12007 {
12010 tree lshift;
12011 tree arg00;
12014 {
12021 }
12022 }
12024 /* If we have a rotate of a bit operation with the rotate count and
12025 the second operand of the bit operation both constant,
12026 permute the two operations. */
12038 /* Two consecutive rotates adding up to the some integer
12039 multiple of the precision of the type can be ignored. */
12047 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12048 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12049 if the latter can be further optimized. */
12054 {
12058 arg1);
12062 arg1);
12066 }
12083 /* Note that the operands of this must be ints
12084 and their values must be 0 or 1.
12085 ("true" is a fixed value perhaps depending on the language.) */
12086 /* If first arg is constant zero, return it. */
12090 /* If either arg is constant true, drop it. */
12094 /* Preserve sequence points. */
12097 /* If second arg is constant zero, result is zero, but first arg
12098 must be evaluated. */
12101 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12102 case will be handled here. */
12106 /* !X && X is always false. */
12110 /* X && !X is always false. */
12115 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12116 means A >= Y && A != MAX, but in this case we know that
12117 A < X <= MAX. */
12121 {
12129 }
12138 /* Note that the operands of this must be ints
12139 and their values must be 0 or true.
12140 ("true" is a fixed value perhaps depending on the language.) */
12141 /* If first arg is constant true, return it. */
12145 /* If either arg is constant zero, drop it. */
12149 /* Preserve sequence points. */
12152 /* If second arg is constant true, result is true, but we must
12153 evaluate first arg. */
12156 /* Likewise for first arg, but note this only occurs here for
12157 TRUTH_OR_EXPR. */
12161 /* !X || X is always true. */
12165 /* X || !X is always true. */
12170 /* (X && !Y) || (!X && Y) is X ^ Y */
12173 {
12190 }
12199 /* If the second arg is constant zero, drop it. */
12202 /* If the second arg is constant true, this is a logical inversion. */
12204 {
12207 }
12208 /* Identical arguments cancel to zero. */
12212 /* !X ^ X is always true. */
12217 /* X ^ !X is always true. */
12233 /* bool_var != 0 becomes bool_var. */
12238 /* bool_var == 1 becomes bool_var. */
12243 /* bool_var != 1 becomes !bool_var. */
12250 /* bool_var == 0 becomes !bool_var. */
12257 /* !exp != 0 becomes !exp */
12262 /* If this is an equality comparison of the address of two non-weak,
12263 unaliased symbols neither of which are extern (since we do not
12264 have access to attributes for externs), then we know the result. */
12269 {
12277 else
12282 type);
12283 }
12285 /* Similarly for a NEGATE_EXPR. */
12289 arg1)))
12294 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12302 arg1),
12305 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12314 {
12318 val,
12322 }
12324 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12331 {
12333 code == NE_EXPR
12336 }
12338 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12343 /* If this is an EQ or NE comparison with zero and ARG0 is
12344 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12345 two operations, but the latter can be done in one less insn
12346 on machines that have only two-operand insns or on which a
12347 constant cannot be the first operand. */
12350 {
12355 {
12362 arg1);
12363 }
12366 {
12373 arg1);
12374 }
12375 }
12377 /* If this is an NE or EQ comparison of zero against the result of a
12378 signed MOD operation whose second operand is a power of 2, make
12379 the MOD operation unsigned since it is simpler and equivalent. */
12387 {
12397 }
12399 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12400 C1 is a valid shift constant, and C2 is a power of two, i.e.
12401 a single bit. */
12405 == INTEGER_CST
12408 {
12413 /* Check for a valid shift count. */
12415 {
12419 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12420 can be rewritten as (X & (C2 << C1)) != 0. */
12422 {
12427 }
12428 /* Otherwise, for signed (arithmetic) shifts,
12429 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12430 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12434 /* Otherwise, of unsigned (logical) shifts,
12435 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12436 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12437 else
12441 arg000);
12442 }
12443 }
12445 /* If we have (A & C) == C where C is a power of 2, convert this into
12446 (A & C) != 0. Similarly for NE_EXPR. */
12452 integer_zero_node));
12454 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12455 bit, then fold the expression into A < 0 or A >= 0. */
12460 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12461 Similarly for NE_EXPR. */
12465 {
12469 tree dandnotc
12472 notc);
12476 }
12478 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12479 Similarly for NE_EXPR. */
12483 {
12485 tree candnotd
12492 }
12494 /* If this is a comparison of a field, we may be able to simplify it. */
12497 /* Handle the constant case even without -O
12498 to make sure the warnings are given. */
12500 {
12504 }
12506 /* Optimize comparisons of strlen vs zero to a compare of the
12507 first character of the string vs zero. To wit,
12508 strlen(ptr) == 0 => *ptr == 0
12509 strlen(ptr) != 0 => *ptr != 0
12510 Other cases should reduce to one of these two (or a constant)
12511 due to the return value of strlen being unsigned. */
12514 {
12522 {
12527 }
12528 }
12530 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12531 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12535 {
12540 {
12542 {
12545 }
12548 }
12549 }
12551 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12557 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12562 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12569 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12577 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12578 (X & C) == 0 when C is a single bit. */
12583 {
12590 arg1));
12591 }
12593 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12594 constant C is a power of two, i.e. a single bit. */
12601 {
12605 }
12607 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12608 when is C is a power of two, i.e. a single bit. */
12615 {
12621 }
12625 {
12628 }
12630 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12638 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12641 {
12654 arg01),
12663 arg01),
12672 arg00),
12681 arg00),
12683 }
12687 {
12694 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12695 operand_equal_p guarantees no side-effects so we don't need
12696 to use omit_one_operand on Z. */
12700 arg10));
12704 arg11));
12708 arg10));
12712 arg11));
12714 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12717 {
12723 }
12724 }
12726 /* Attempt to simplify equality/inequality comparisons of complex
12727 values. Only lower the comparison if the result is known or
12728 can be simplified to a single scalar comparison. */
12733 {
12738 {
12741 }
12742 else
12743 {
12746 }
12749 {
12752 }
12753 else
12754 {
12757 }
12761 {
12763 {
12768 }
12769 else
12770 {
12775 }
12776 }
12780 {
12782 {
12787 }
12788 else
12789 {
12794 }
12795 }
12796 }
12808 /* Transform comparisons of the form X +- C CMP X. */
12815 {
12822 else
12825 /* (X - c) > X becomes false. */
12829 {
12833 "occur when assuming that (X - c) > X "
12835 WARN_STRICT_OVERFLOW_ALL);
12837 }
12839 /* Likewise (X + c) < X becomes false. */
12843 {
12847 "occur when assuming that "
12849 WARN_STRICT_OVERFLOW_ALL);
12851 }
12853 /* Convert (X - c) <= X to true. */
12858 {
12862 "occur when assuming that "
12864 WARN_STRICT_OVERFLOW_ALL);
12866 }
12868 /* Convert (X + c) >= X to true. */
12873 {
12877 "occur when assuming that "
12879 WARN_STRICT_OVERFLOW_ALL);
12881 }
12884 {
12885 /* Convert X + c > X and X - c < X to true for integers. */
12889 {
12892 "not occur when assuming that "
12894 WARN_STRICT_OVERFLOW_ALL);
12896 }
12901 {
12904 "not occur when assuming that "
12906 WARN_STRICT_OVERFLOW_ALL);
12908 }
12910 /* Convert X + c <= X and X - c >= X to false for integers. */
12914 {
12917 "not occur when assuming that "
12919 WARN_STRICT_OVERFLOW_ALL);
12921 }
12926 {
12929 "not occur when assuming that "
12931 WARN_STRICT_OVERFLOW_ALL);
12933 }
12934 }
12935 }
12937 /* Comparisons with the highest or lowest possible integer of
12938 the specified precision will have known values. */
12939 {
12945 {
12952 {
12965 /* The GE_EXPR and LT_EXPR cases above are not normally
12966 reached because of previous transformations. */
12970 }
12973 {
12980 arg1);
12986 arg0),
12987 arg1);
12990 }
12993 {
13008 }
13011 {
13018 arg1);
13024 arg0),
13025 arg1);
13028 }
13032 /* We will flip the signedness of the comparison operator
13033 associated with the mode of arg1, so the sign bit is
13034 specified by this mode. Check that arg1 is the signed
13035 max associated with this sign bit. */
13037 /* signed_type does not work on pointer types. */
13039 {
13040 /* The following case also applies to X < signed_max+1
13041 and X >= signed_max+1 because previous transformations. */
13043 {
13049 }
13050 }
13051 }
13052 }
13054 /* If we are comparing an ABS_EXPR with a constant, we can
13055 convert all the cases into explicit comparisons, but they may
13056 well not be faster than doing the ABS and one comparison.
13057 But ABS (X) <= C is a range comparison, which becomes a subtraction
13058 and a comparison, and is probably faster. */
13072 /* Convert ABS_EXPR<x> >= 0 to true. */
13079 {
13082 "when simplifying comparison of "
13084 WARN_STRICT_OVERFLOW_CONDITIONAL);
13087 arg0);
13088 }
13090 /* Convert ABS_EXPR<x> < 0 to false. */
13095 {
13098 "when simplifying comparison of "
13100 WARN_STRICT_OVERFLOW_CONDITIONAL);
13103 arg0);
13104 }
13106 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13107 and similarly for >= into !=. */
13117 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13118 otherwise Y might be >= # of bits in X's type and thus e.g.
13119 (unsigned char) (1 << Y) for Y 15 might be 0.
13120 If the cast is widening, then 1 << Y should have unsigned type,
13121 otherwise if Y is number of bits in the signed shift type minus 1,
13122 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13123 31 might be 0xffffffff80000000. */
13134 {
13140 }
13153 {
13157 }
13159 /* If the first operand is NaN, the result is constant. */
13163 {
13165 ? integer_zero_node
13168 }
13170 /* If the second operand is NaN, the result is constant. */
13174 {
13176 ? integer_zero_node
13179 }
13181 /* Simplify unordered comparison of something with itself. */
13187 && !flag_trapping_math
13191 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13192 {
13204 }
13209 /* When pedantic, a compound expression can be neither an lvalue
13210 nor an integer constant expression. */
13213 /* Don't let (0, 0) be null pointer constant. */
13219 /* An ASSERT_EXPR should never be passed to fold_binary. */
13225 }
13227 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13228 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13229 of GOTO_EXPR. */
13231 static tree
13233 {
13235 {
13242 /* ... fall through ... */
13246 }
13247 }
13249 /* Return whether the sub-tree ST contains a label which is accessible from
13250 outside the sub-tree. */
13252 static bool
13254 {
13255 return
13257 }
13259 /* Fold a ternary expression of code CODE and type TYPE with operands
13260 OP0, OP1, and OP2. Return the folded expression if folding is
13261 successful. Otherwise, return NULL_TREE. */
13263 tree
13266 {
13267 tree tem;
13274 /* If this is a commutative operation, and OP0 is a constant, move it
13275 to OP1 to reduce the number of tests below. */
13284 /* Strip any conversions that don't change the mode. This is safe
13285 for every expression, except for a comparison expression because
13286 its signedness is derived from its operands. So, in the latter
13287 case, only strip conversions that don't change the signedness.
13289 Note that this is done as an internal manipulation within the
13290 constant folder, in order to find the simplest representation of
13291 the arguments so that their form can be studied. In any cases,
13292 the appropriate type conversions should be put back in the tree
13293 that will get out of the constant folder. */
13295 {
13298 }
13301 {
13304 }
13307 {
13310 }
13313 {
13317 {
13323 }
13328 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13329 so all simple results must be passed through pedantic_non_lvalue. */
13331 {
13334 /* Only optimize constant conditions when the selected branch
13335 has the same type as the COND_EXPR. This avoids optimizing
13336 away "c ? x : throw", where the throw has a void type.
13337 Avoid throwing away that operand which contains label. */
13344 }
13346 {
13351 {
13356 {
13364 }
13368 }
13369 }
13371 /* If we have A op B ? A : C, we may be able to convert this to a
13372 simpler expression, depending on the operation and the values
13373 of B and C. Signed zeros prevent all of these transformations,
13374 for reasons given above each one.
13376 Also try swapping the arguments and inverting the conditional. */
13381 {
13385 }
13389 op2,
13392 {
13396 {
13400 }
13401 }
13403 /* If the second operand is simpler than the third, swap them
13404 since that produces better jump optimization results. */
13407 {
13409 /* See if this can be inverted. If it can't, possibly because
13410 it was a floating-point inequality comparison, don't do
13411 anything. */
13415 }
13417 /* Convert A ? 1 : 0 to simply A. */
13422 /* If we try to convert OP0 to our type, the
13423 call to fold will try to move the conversion inside
13424 a COND, which will recurse. In that case, the COND_EXPR
13425 is probably the best choice, so leave it alone. */
13429 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13430 over COND_EXPR in cases such as floating point comparisons. */
13439 arg0)));
13441 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13446 {
13447 /* sign_bit_p looks through both zero and sign extensions,
13448 but for this optimization only sign extensions are
13449 usable. */
13452 {
13455 {
13458 }
13460 }
13461 /* sign_bit_p only checks ARG1 bits within A's precision.
13462 If <sign bit of A> has wider type than A, bits outside
13463 of A's precision in <sign bit of A> need to be checked.
13464 If they are all 0, this optimization needs to be done
13465 in unsigned A's type, if they are all 1 in signed A's type,
13466 otherwise this can't be done. */
13472 {
13474 tree tem_type;
13487 {
13490 }
13492 {
13495 }
13496 else
13498 }
13501 return
13507 arg1)));
13508 }
13510 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13511 already handled above. */
13516 {
13525 }
13527 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13528 is probably obsolete because the first operand should be a
13529 truth value (that's why we have the two cases above), but let's
13530 leave it in until we can confirm this for all front-ends. */
13542 /* Disable the transformations below for vectors, since
13543 fold_binary_op_with_conditional_arg may undo them immediately,
13544 yielding an infinite loop. */
13548 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13557 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13562 {
13564 /* Only perform transformation if ARG0 is easily inverted. */
13568 ? BIT_IOR_EXPR
13571 arg1);
13572 }
13574 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13579 {
13581 /* Only perform transformation if ARG0 is easily inverted. */
13587 op2);
13588 }
13590 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13602 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13603 of fold_ternary on them. */
13613 {
13623 {
13628 {
13636 }
13638 /* Constructor elements can be subvectors. */
13641 {
13645 }
13647 /* We keep an exact subset of the constructor elements. */
13649 {
13655 {
13659 }
13667 CONSTRUCTOR_ELT
13670 }
13671 /* The bitfield references a single constructor element. */
13673 {
13678 else
13682 }
13683 }
13684 }
13686 /* A bit-field-ref that referenced the full argument can be stripped. */
13692 /* On constants we can use native encode/interpret to constant
13693 fold (nearly) all BIT_FIELD_REFs. */
13697 /* This limitation should not be necessary, we just need to
13698 round this up to mode size. */
13700 /* Need bit-shifting of the buffer to relax the following. */
13702 {
13707 /* ??? We cannot tell native_encode_expr to start at
13708 some random byte only. So limit us to a reasonable amount
13709 of work. */
13711 {
13716 {
13722 }
13723 }
13724 }
13729 /* For integers we can decompose the FMA if possible. */
13741 {
13757 {
13762 /* Make sure that the perm value is in an acceptable
13763 range. */
13772 else
13777 }
13780 {
13785 }
13790 {
13795 }
13801 {
13805 }
13810 /* Some targets are deficient and fail to expand a single
13811 argument permutation while still allowing an equivalent
13812 2-argument version. */
13816 {
13819 }
13822 {
13829 }
13833 }
13839 }
13841 /* Perform constant folding and related simplification of EXPR.
13842 The related simplifications include x*1 => x, x*0 => 0, etc.,
13843 and application of the associative law.
13844 NOP_EXPR conversions may be removed freely (as long as we
13845 are careful not to change the type of the overall expression).
13846 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13847 but we can constant-fold them if they have constant operands. */
13849 #ifdef ENABLE_FOLD_CHECKING
13850 # define fold(x) fold_1 (x)
13852 static
13853 #endif
13854 tree
13856 {
13860 tree tem;
13863 /* Return right away if a constant. */
13867 /* CALL_EXPR-like objects with variable numbers of operands are
13868 treated specially. */
13870 {
13872 {
13875 }
13877 }
13880 {
13885 {
13903 }
13904 }
13907 {
13909 {
13916 {
13921 /* Find a matching index by means of a binary search. */
13923 {
13939 else
13941 }
13942 }
13945 }
13947 /* Return a VECTOR_CST if possible. */
13949 {
13956 tree value;
13959 {
13963 {
13966 }
13967 else
13969 }
13974 }
13982 }
13984 #ifdef ENABLE_FOLD_CHECKING
13985 #undef fold
13992 /* When --enable-checking=fold, compute a digest of expr before
13993 and after actual fold call to see if fold did not accidentally
13994 change original expr. */
13996 tree
13998 {
13999 tree ret;
14019 }
14021 void
14023 {
14034 }
14036 static void
14038 {
14040 }
14042 static void
14045 {
14051 recursive_label:
14061 {
14062 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14066 }
14073 {
14074 /* Allow these fields to be modified. */
14075 tree tmp;
14083 {
14086 }
14087 }
14098 {
14101 {
14116 }
14120 {
14133 }
14150 {
14156 }
14159 {
14161 {
14164 }
14166 }
14177 {
14180 }
14190 }
14191 }
14193 /* Helper function for outputting the checksum of a tree T. When
14194 debugging with gdb, you can "define mynext" to be "next" followed
14195 by "call debug_fold_checksum (op0)", then just trace down till the
14196 outputs differ. */
14198 DEBUG_FUNCTION void
14200 {
14215 }
14217 #endif
14219 /* Fold a unary tree expression with code CODE of type TYPE with an
14220 operand OP0. LOC is the location of the resulting expression.
14221 Return a folded expression if successful. Otherwise, return a tree
14222 expression with code CODE of type TYPE with an operand OP0. */
14224 tree
14227 {
14228 tree tem;
14229 #ifdef ENABLE_FOLD_CHECKING
14238 #endif
14244 #ifdef ENABLE_FOLD_CHECKING
14251 #endif
14253 }
14255 /* Fold a binary tree expression with code CODE of type TYPE with
14256 operands OP0 and OP1. LOC is the location of the resulting
14257 expression. Return a folded expression if successful. Otherwise,
14258 return a tree expression with code CODE of type TYPE with operands
14259 OP0 and OP1. */
14261 tree
14264 MEM_STAT_DECL)
14265 {
14266 tree tem;
14267 #ifdef ENABLE_FOLD_CHECKING
14284 #endif
14290 #ifdef ENABLE_FOLD_CHECKING
14305 #endif
14307 }
14309 /* Fold a ternary tree expression with code CODE of type TYPE with
14310 operands OP0, OP1, and OP2. Return a folded expression if
14311 successful. Otherwise, return a tree expression with code CODE of
14312 type TYPE with operands OP0, OP1, and OP2. */
14314 tree
14317 {
14318 tree tem;
14319 #ifdef ENABLE_FOLD_CHECKING
14343 #endif
14350 #ifdef ENABLE_FOLD_CHECKING
14373 #endif
14375 }
14377 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14378 arguments in ARGARRAY, and a null static chain.
14379 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14380 of type TYPE from the given operands as constructed by build_call_array. */
14382 tree
14385 {
14386 tree tem;
14387 #ifdef ENABLE_FOLD_CHECKING
14406 #endif
14412 #ifdef ENABLE_FOLD_CHECKING
14428 #endif
14430 }
14432 /* Perform constant folding and related simplification of initializer
14433 expression EXPR. These behave identically to "fold_buildN" but ignore
14434 potential run-time traps and exceptions that fold must preserve. */
14436 #define START_FOLD_INIT \
14437 int saved_signaling_nans = flag_signaling_nans;\
14438 int saved_trapping_math = flag_trapping_math;\
14439 int saved_rounding_math = flag_rounding_math;\
14440 int saved_trapv = flag_trapv;\
14441 int saved_folding_initializer = folding_initializer;\
14442 flag_signaling_nans = 0;\
14443 flag_trapping_math = 0;\
14444 flag_rounding_math = 0;\
14445 flag_trapv = 0;\
14446 folding_initializer = 1;
14448 #define END_FOLD_INIT \
14449 flag_signaling_nans = saved_signaling_nans;\
14450 flag_trapping_math = saved_trapping_math;\
14451 flag_rounding_math = saved_rounding_math;\
14452 flag_trapv = saved_trapv;\
14453 folding_initializer = saved_folding_initializer;
14455 tree
14458 {
14459 tree result;
14460 START_FOLD_INIT;
14464 END_FOLD_INIT;
14466 }
14468 tree
14471 {
14472 tree result;
14473 START_FOLD_INIT;
14477 END_FOLD_INIT;
14479 }
14481 tree
14484 {
14485 tree result;
14486 START_FOLD_INIT;
14490 END_FOLD_INIT;
14492 }
14494 #undef START_FOLD_INIT
14495 #undef END_FOLD_INIT
14497 /* Determine if first argument is a multiple of second argument. Return 0 if
14498 it is not, or we cannot easily determined it to be.
14500 An example of the sort of thing we care about (at this point; this routine
14501 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14502 fold cases do now) is discovering that
14504 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14506 is a multiple of
14508 SAVE_EXPR (J * 8)
14510 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14512 This code also handles discovering that
14514 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14516 is a multiple of 8 so we don't have to worry about dealing with a
14517 possible remainder.
14519 Note that we *look* inside a SAVE_EXPR only to determine how it was
14520 calculated; it is not safe for fold to do much of anything else with the
14521 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14522 at run time. For example, the latter example above *cannot* be implemented
14523 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14524 evaluation time of the original SAVE_EXPR is not necessarily the same at
14525 the time the new expression is evaluated. The only optimization of this
14526 sort that would be valid is changing
14528 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14530 divided by 8 to
14532 SAVE_EXPR (I) * SAVE_EXPR (J)
14534 (where the same SAVE_EXPR (J) is used in the original and the
14535 transformed version). */
14537 int
14539 {
14547 {
14549 /* Bitwise and provides a power of two multiple. If the mask is
14550 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14553 /* FALLTHRU */
14566 {
14570 /* const_binop may not detect overflow correctly,
14571 so check for it explicitly here. */
14575 size_one_node,
14576 op1)))
14579 }
14583 /* Can't handle conversions from non-integral or wider integral type. */
14589 /* .. fall through ... */
14606 SIGNED);
14610 }
14611 }
14613 /* Return true if CODE or TYPE is known to be non-negative. */
14615 static bool
14617 {
14620 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14621 have a signed:1 type (where the value is -1 and 0). */
14624 }
14626 /* Return true if (CODE OP0) is known to be non-negative. If the return
14627 value is based on the assumption that signed overflow is undefined,
14628 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14629 *STRICT_OVERFLOW_P. */
14631 bool
14634 {
14639 {
14641 /* We can't return 1 if flag_wrapv is set because
14642 ABS_EXPR<INT_MIN> = INT_MIN. */
14646 {
14649 }
14656 strict_overflow_p);
14658 CASE_CONVERT:
14659 {
14664 {
14667 strict_overflow_p);
14669 {
14673 strict_overflow_p);
14674 }
14675 }
14677 {
14680 strict_overflow_p);
14684 }
14685 }
14690 }
14692 /* We don't know sign of `t', so be conservative and return false. */
14694 }
14696 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14697 value is based on the assumption that signed overflow is undefined,
14698 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14699 *STRICT_OVERFLOW_P. */
14701 bool
14704 {
14709 {
14714 strict_overflow_p)
14716 strict_overflow_p));
14718 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14719 both unsigned and at least 2 bits shorter than the result. */
14723 {
14728 {
14732 }
14733 }
14738 {
14739 /* x * x is always non-negative for floating point x
14740 or without overflow. */
14744 {
14749 }
14750 }
14752 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14753 both unsigned and their total bits is shorter than the result. */
14757 {
14776 {
14786 }
14787 }
14793 strict_overflow_p)
14795 strict_overflow_p));
14806 strict_overflow_p)
14808 strict_overflow_p));
14815 strict_overflow_p);
14818 }
14820 /* We don't know sign of `t', so be conservative and return false. */
14822 }
14824 /* Return true if T is known to be non-negative. If the return
14825 value is based on the assumption that signed overflow is undefined,
14826 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14827 *STRICT_OVERFLOW_P. */
14829 bool
14831 {
14836 {
14848 strict_overflow_p)
14850 strict_overflow_p));
14854 }
14855 /* We don't know sign of `t', so be conservative and return false. */
14857 }
14859 /* Return true if T is known to be non-negative. If the return
14860 value is based on the assumption that signed overflow is undefined,
14861 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14862 *STRICT_OVERFLOW_P. */
14864 bool
14867 {
14870 {
14890 /* Always true. */
14894 /* sqrt(-0.0) is -0.0. */
14898 strict_overflow_p);
14935 /* True if the 1st argument is nonnegative. */
14937 strict_overflow_p);
14940 /* True if the 1st OR 2nd arguments are nonnegative. */
14942 strict_overflow_p)
14944 strict_overflow_p)));
14947 /* True if the 1st AND 2nd arguments are nonnegative. */
14949 strict_overflow_p)
14951 strict_overflow_p)));
14954 /* True if the 2nd argument is nonnegative. */
14956 strict_overflow_p);
14959 /* True if the 1st argument is nonnegative or the second
14960 argument is an even integer. */
14965 strict_overflow_p);
14968 /* True if the 1st argument is nonnegative or the second
14969 argument is an even integer valued real. */
14971 {
14972 REAL_VALUE_TYPE c;
14973 HOST_WIDE_INT n;
14978 {
14979 REAL_VALUE_TYPE cint;
14983 }
14984 }
14986 strict_overflow_p);
14990 }
14992 type);
14993 }
14995 /* Return true if T is known to be non-negative. If the return
14996 value is based on the assumption that signed overflow is undefined,
14997 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14998 *STRICT_OVERFLOW_P. */
15000 static bool
15002 {
15008 {
15010 {
15014 /* If the initializer is non-void, then it's a normal expression
15015 that will be assigned to the slot. */
15019 /* Otherwise, the initializer sets the slot in some way. One common
15020 way is an assignment statement at the end of the initializer. */
15022 {
15030 else
15032 }
15036 strict_overflow_p);
15039 }
15042 {
15048 arg0,
15049 arg1,
15050 strict_overflow_p);
15051 }
15055 strict_overflow_p);
15058 strict_overflow_p);
15061 strict_overflow_p);
15066 }
15068 /* We don't know sign of `t', so be conservative and return false. */
15070 }
15072 /* Return true if T is known to be non-negative. If the return
15073 value is based on the assumption that signed overflow is undefined,
15074 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15075 *STRICT_OVERFLOW_P. */
15077 bool
15079 {
15086 {
15093 strict_overflow_p);
15099 strict_overflow_p);
15108 }
15111 {
15119 strict_overflow_p);
15124 strict_overflow_p);
15137 }
15138 }
15140 /* Return true if `t' is known to be non-negative. Handle warnings
15141 about undefined signed overflow. */
15143 bool
15145 {
15152 "determining that expression is always "
15154 WARN_STRICT_OVERFLOW_MISC);
15156 }
15159 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15160 For floating point we further ensure that T is not denormal.
15161 Similar logic is present in nonzero_address in rtlanal.h.
15163 If the return value is based on the assumption that signed overflow
15164 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15165 change *STRICT_OVERFLOW_P. */
15167 bool
15170 {
15172 {
15175 strict_overflow_p);
15178 {
15184 strict_overflow_p));
15185 }
15190 strict_overflow_p);
15194 }
15197 }
15199 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15200 For floating point we further ensure that T is not denormal.
15201 Similar logic is present in nonzero_address in rtlanal.h.
15203 If the return value is based on the assumption that signed overflow
15204 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15205 change *STRICT_OVERFLOW_P. */
15207 bool
15209 tree type,
15210 tree op0,
15212 {
15215 {
15219 {
15220 /* With the presence of negative values it is hard
15221 to say something. */
15228 /* One of operands must be positive and the other non-negative. */
15229 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15230 overflows, on a twos-complement machine the sum of two
15231 nonnegative numbers can never be zero. */
15233 strict_overflow_p)
15235 strict_overflow_p));
15236 }
15241 {
15243 strict_overflow_p)
15245 strict_overflow_p))
15246 {
15249 }
15250 }
15259 {
15262 }
15269 {
15273 /* When both operands are nonzero, then MAX must be too. */
15275 strict_overflow_p))
15278 /* MAX where operand 0 is positive is positive. */
15280 strict_overflow_p);
15281 }
15282 /* MAX where operand 1 is positive is positive. */
15287 {
15291 }
15296 strict_overflow_p)
15298 strict_overflow_p));
15302 }
15305 }
15307 /* Return true when T is an address and is known to be nonzero.
15308 For floating point we further ensure that T is not denormal.
15309 Similar logic is present in nonzero_address in rtlanal.h.
15311 If the return value is based on the assumption that signed overflow
15312 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15313 change *STRICT_OVERFLOW_P. */
15315 bool
15317 {
15320 {
15325 {
15334 /* For objects in symbol table check if we know they are non-zero.
15335 Don't do anything for variables and functions before symtab is built;
15336 it is quite possible that they will be declared weak later. */
15338 {
15344 else
15346 }
15348 /* Function local objects are never NULL. */
15355 /* Constants are never weak. */
15360 }
15368 {
15372 }
15377 }
15379 }
15381 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15382 attempt to fold the expression to a constant without modifying TYPE,
15383 OP0 or OP1.
15385 If the expression could be simplified to a constant, then return
15386 the constant. If the expression would not be simplified to a
15387 constant, then return NULL_TREE. */
15389 tree
15391 {
15394 }
15396 /* Given the components of a unary expression CODE, TYPE and OP0,
15397 attempt to fold the expression to a constant without modifying
15398 TYPE or OP0.
15400 If the expression could be simplified to a constant, then return
15401 the constant. If the expression would not be simplified to a
15402 constant, then return NULL_TREE. */
15404 tree
15406 {
15409 }
15411 /* If EXP represents referencing an element in a constant string
15412 (either via pointer arithmetic or array indexing), return the
15413 tree representing the value accessed, otherwise return NULL. */
15415 tree
15417 {
15421 {
15423 tree index;
15424 tree string;
15429 else
15430 {
15434 /* Optimize the special-case of a zero lower bound.
15436 We convert the low_bound to sizetype to avoid some problems
15437 with constant folding. (E.g. suppose the lower bound is 1,
15438 and its mode is QI. Without the conversion,l (ARRAY
15439 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15440 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15446 }
15459 }
15461 }
15463 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15464 an integer constant, real, or fixed-point constant.
15466 TYPE is the type of the result. */
15468 static tree
15470 {
15474 {
15476 {
15483 }
15490 {
15491 FIXED_VALUE_TYPE f;
15496 /* Propagate overflow flags. */
15500 }
15504 }
15507 }
15509 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15510 an integer constant or real constant.
15512 TYPE is the type of the result. */
15514 tree
15516 {
15520 {
15522 {
15523 /* If the value is unsigned or non-negative, then the absolute value
15524 is the same as the ordinary value. */
15528 /* If the value is negative, then the absolute value is
15529 its negation. */
15530 else
15531 {
15536 }
15537 }
15543 else
15549 }
15552 }
15554 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15555 constant. TYPE is the type of the result. */
15557 static tree
15559 {
15563 }
15565 /* Given CODE, a relational operator, the target type, TYPE and two
15566 constant operands OP0 and OP1, return the result of the
15567 relational operation. If the result is not a compile time
15568 constant, then return NULL_TREE. */
15570 static tree
15572 {
15575 /* From here on, the only cases we handle are when the result is
15576 known to be a constant. */
15579 {
15583 /* Handle the cases where either operand is a NaN. */
15585 {
15587 {
15615 }
15618 }
15621 }
15624 {
15628 }
15630 /* Handle equality/inequality of complex constants. */
15632 {
15643 else
15645 }
15648 {
15655 {
15667 }
15670 }
15672 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15674 To compute GT, swap the arguments and do LT.
15675 To compute GE, do LT and invert the result.
15676 To compute LE, swap the arguments, do LT and invert the result.
15677 To compute NE, do EQ and invert the result.
15679 Therefore, the code below must handle only EQ and LT. */
15682 {
15687 }
15689 /* Note that it is safe to invert for real values here because we
15690 have already handled the one case that it matters. */
15694 {
15697 }
15699 /* Compute a result for LT or EQ if args permit;
15700 Otherwise return T. */
15702 {
15705 else
15707 }
15708 else
15714 }
15716 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15717 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15718 itself. */
15720 tree
15722 {
15723 /* If the expression does not have side effects then we don't have to wrap
15724 it with a cleanup point expression. */
15728 /* If the expression is a return, check to see if the expression inside the
15729 return has no side effects or the right hand side of the modify expression
15730 inside the return. If either don't have side effects set we don't need to
15731 wrap the expression in a cleanup point expression. Note we don't check the
15732 left hand side of the modify because it should always be a return decl. */
15734 {
15741 }
15744 }
15746 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15747 of an indirection through OP0, or NULL_TREE if no simplification is
15748 possible. */
15750 tree
15752 {
15754 tree subtype;
15762 {
15765 /* *&CONST_DECL -> to the value of the const decl. */
15768 /* *&p => p; make sure to handle *&"str"[cst] here. */
15770 {
15774 else
15776 }
15777 /* *(foo *)&fooarray => fooarray[0] */
15780 && (!in_gimple_form
15782 {
15792 }
15793 /* *(foo *)&complexfoo => __real__ complexfoo */
15797 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15800 {
15804 }
15805 }
15809 {
15815 {
15816 tree op00type;
15820 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15823 {
15835 }
15836 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15839 {
15843 }
15844 /* ((foo *)&fooarray)[1] => fooarray[1] */
15847 {
15857 }
15858 }
15859 }
15861 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15864 && (!in_gimple_form
15866 {
15867 tree type_domain;
15877 NULL_TREE);
15878 }
15881 }
15883 /* Builds an expression for an indirection through T, simplifying some
15884 cases. */
15886 tree
15888 {
15896 }
15898 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15900 tree
15902 {
15907 else
15909 }
15911 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15912 whose result is ignored. The type of the returned tree need not be
15913 the same as the original expression. */
15915 tree
15917 {
15923 {
15934 else
15940 {
15956 }
15961 }
15962 }
15964 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15966 tree
15968 {
15974 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15975 have to do anything. Only do this when we are not given a const,
15976 because in that case, this check is more expensive than just
15977 doing it. */
15979 {
15984 }
15986 /* If divisor is a power of two, simplify this to bit manipulation. */
15988 {
15990 {
16004 }
16005 else
16006 {
16007 tree t;
16013 }
16014 }
16015 else
16016 {
16021 }
16024 }
16026 /* Likewise, but round down. */
16028 tree
16030 {
16037 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16038 have to do anything. Only do this when we are not given a const,
16039 because in that case, this check is more expensive than just
16040 doing it. */
16042 {
16047 }
16049 /* If divisor is a power of two, simplify this to bit manipulation. */
16051 {
16052 tree t;
16056 }
16057 else
16058 {
16063 }
16066 }
16068 /* Returns the pointer to the base of the object addressed by EXP and
16069 extracts the information about the offset of the access, storing it
16070 to PBITPOS and POFFSET. */
16072 static tree
16075 {
16076 tree core;
16077 machine_mode mode;
16079 HOST_WIDE_INT bitsize;
16083 {
16088 }
16089 else
16090 {
16094 }
16097 }
16099 /* Returns true if addresses of E1 and E2 differ by a constant, false
16100 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16102 bool
16104 {
16118 {
16128 }
16130 {
16131 /* If only one of the offsets is non-constant, the difference cannot
16132 be a constant. */
16134 }
16135 else
16140 }
16142 /* Simplify the floating point expression EXP when the sign of the
16143 result is not significant. Return NULL_TREE if no simplification
16144 is possible. */
16146 tree
16148 {
16153 {
16189 {
16192 {
16194 /* Strip copysign function call, return the 1st argument. */
16200 /* Strip sign ops from the argument of "odd" math functions. */
16202 {
16206 }
16208 }
16209 }
16214 }
16216 }