| blob | d896d7a16750b80b7054ac61cb22832d2165938d |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2015 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 *,
158 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
159 Otherwise, return LOC. */
161 static location_t
163 {
166 }
168 /* Similar to protected_set_expr_location, but never modify x in place,
169 if location can and needs to be set, unshare it. */
173 {
179 {
182 }
184 }
185 \f
186 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
187 division and returns the quotient. Otherwise returns
188 NULL_TREE. */
190 tree
192 {
193 widest_int quo;
200 }
201 \f
202 /* This is nonzero if we should defer warnings about undefined
203 overflow. This facility exists because these warnings are a
204 special case. The code to estimate loop iterations does not want
205 to issue any warnings, since it works with expressions which do not
206 occur in user code. Various bits of cleanup code call fold(), but
207 only use the result if it has certain characteristics (e.g., is a
208 constant); that code only wants to issue a warning if the result is
209 used. */
213 /* If a warning about undefined overflow is deferred, this is the
214 warning. Note that this may cause us to turn two warnings into
215 one, but that is fine since it is sufficient to only give one
216 warning per expression. */
220 /* If a warning about undefined overflow is deferred, this is the
221 level at which the warning should be emitted. */
225 /* Start deferring overflow warnings. We could use a stack here to
226 permit nested calls, but at present it is not necessary. */
228 void
230 {
232 }
234 /* Stop deferring overflow warnings. If there is a pending warning,
235 and ISSUE is true, then issue the warning if appropriate. STMT is
236 the statement with which the warning should be associated (used for
237 location information); STMT may be NULL. CODE is the level of the
238 warning--a warn_strict_overflow_code value. This function will use
239 the smaller of CODE and the deferred code when deciding whether to
240 issue the warning. CODE may be zero to mean to always use the
241 deferred code. */
243 void
245 {
247 location_t locus;
252 {
258 }
269 /* Use the smallest code level when deciding to issue the
270 warning. */
279 else
282 }
284 /* Stop deferring overflow warnings, ignoring any deferred
285 warnings. */
287 void
289 {
291 }
293 /* Whether we are deferring overflow warnings. */
295 bool
297 {
299 }
301 /* This is called when we fold something based on the fact that signed
302 overflow is undefined. */
304 static void
306 {
308 {
311 {
314 }
315 }
318 }
319 \f
320 /* Return true if the built-in mathematical function specified by CODE
321 is odd, i.e. -f(x) == f(-x). */
323 static bool
325 {
327 {
361 }
363 }
365 /* Check whether we may negate an integer constant T without causing
366 overflow. */
368 bool
370 {
371 tree type;
380 }
382 /* Determine whether an expression T can be cheaply negated using
383 the function negate_expr without introducing undefined overflow. */
385 static bool
387 {
388 tree type;
397 {
402 /* Check that -CST will not overflow type. */
415 /* We want to canonicalize to positive real constants. Pretend
416 that only negative ones can be easily negated. */
424 {
435 }
448 /* -(A + B) -> (-B) - A. */
453 /* -(A + B) -> (-A) - B. */
457 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
467 /* Fall through. */
478 /* In general we can't negate A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. But if overflow is
481 undefined, we can negate, because - (INT_MIN / 1) is an
482 overflow. */
484 {
487 /* If overflow is undefined then we have to be careful because
488 we ask whether it's ok to associate the negate with the
489 division which is not ok for example for
490 -((a - b) / c) where (-(a - b)) / c may invoke undefined
491 overflow because of negating INT_MIN. So do not use
492 negate_expr_p here but open-code the two important cases. */
497 }
503 /* Negate -((double)float) as (double)(-float). */
505 {
509 }
513 /* Negate -f(x) as f(-x). */
519 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
521 {
525 }
530 }
532 }
534 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
535 simplification is possible.
536 If negate_expr_p would return true for T, NULL_TREE will never be
537 returned. */
539 static tree
541 {
543 tree tem;
546 {
547 /* Convert - (~A) to A + 1. */
573 {
578 }
582 {
587 {
591 }
594 }
617 {
618 /* -(A + B) -> (-B) - A. */
622 {
626 }
628 /* -(A + B) -> (-A) - B. */
630 {
634 }
635 }
639 /* - (A - B) -> B - A */
651 /* Fall through. */
655 {
664 }
670 /* In general we can't negate A / B, because if A is INT_MIN and
671 B is 1, we may turn this into INT_MIN / -1 which is undefined
672 and actually traps on some architectures. But if overflow is
673 undefined, we can negate, because - (INT_MIN / 1) is an
674 overflow. */
676 {
681 {
688 }
689 /* If overflow is undefined then we have to be careful because
690 we ask whether it's ok to associate the negate with the
691 division which is not ok for example for
692 -((a - b) / c) where (-(a - b)) / c may invoke undefined
693 overflow because of negating INT_MIN. So do not use
694 negate_expr_p here but open-code the two important cases. */
703 }
707 /* Convert -((double)float) into (double)(-float). */
709 {
713 }
717 /* Negate -f(x) as f(-x). */
720 {
726 }
730 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
732 {
735 {
742 }
743 }
748 }
751 }
753 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
754 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
755 return NULL_TREE. */
757 static tree
759 {
761 location_t loc;
774 }
775 \f
776 /* Split a tree IN into a constant, literal and variable parts that could be
777 combined with CODE to make IN. "constant" means an expression with
778 TREE_CONSTANT but that isn't an actual constant. CODE must be a
779 commutative arithmetic operation. Store the constant part into *CONP,
780 the literal in *LITP and return the variable part. If a part isn't
781 present, set it to null. If the tree does not decompose in this way,
782 return the entire tree as the variable part and the other parts as null.
784 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
785 case, we negate an operand that was subtracted. Except if it is a
786 literal for which we use *MINUS_LITP instead.
788 If NEGATE_P is true, we are negating all of IN, again except a literal
789 for which we use *MINUS_LITP instead.
791 If IN is itself a literal or constant, return it as appropriate.
793 Note that we do not guarantee that any of the three values will be the
794 same type as IN, but they will have the same signedness and mode. */
796 static tree
799 {
806 /* Strip any conversions that don't change the machine mode or signedness. */
815 /* We can associate addition and subtraction together (even
816 though the C standard doesn't say so) for integers because
817 the value is not affected. For reals, the value might be
818 affected, so we can't. */
821 {
827 /* First see if either of the operands is a literal, then a constant. */
840 /* If we haven't dealt with either operand, this is not a case we can
841 decompose. Otherwise, VAR is either of the ones remaining, if any. */
846 else
849 /* Now do any needed negations. */
856 }
859 {
860 /* -X - 1 is folded to ~X, undo that here. */
863 }
866 else
870 {
877 }
880 }
882 /* Re-associate trees split by the above function. T1 and T2 are
883 either expressions to associate or null. Return the new
884 expression, if any. LOC is the location of the new expression. If
885 we build an operation, do it in TYPE and with CODE. */
887 static tree
889 {
895 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
896 try to fold this since we will have infinite recursion. But do
897 deal with any NEGATE_EXPRs. */
900 {
902 {
915 }
917 {
920 }
924 }
928 }
929 \f
930 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
931 for use in int_const_binop, size_binop and size_diffop. */
933 static bool
935 {
942 {
951 }
956 }
959 /* Combine two integer constants ARG1 and ARG2 under operation CODE
960 to produce a new constant. Return NULL_TREE if we don't know how
961 to evaluate CODE at compile-time. */
963 static tree
966 {
967 wide_int res;
968 tree t;
977 {
993 {
997 else
999 }
1002 /* It's unclear from the C standard whether shifts can overflow.
1003 The following code ignores overflow; perhaps a C standard
1004 interpretation ruling is needed. */
1006 else
1013 {
1017 else
1019 }
1023 else
1102 }
1110 }
1112 tree
1114 {
1116 }
1118 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1119 constant. We assume ARG1 and ARG2 have the same data type, or at least
1120 are the same kind of constant and the same machine mode. Return zero if
1121 combining the constants is not allowed in the current operating mode. */
1123 static tree
1125 {
1126 /* Sanity check for the recursive cases. */
1134 {
1140 }
1143 {
1144 machine_mode mode;
1145 REAL_VALUE_TYPE d1;
1146 REAL_VALUE_TYPE d2;
1147 REAL_VALUE_TYPE value;
1148 REAL_VALUE_TYPE result;
1152 /* The following codes are handled by real_arithmetic. */
1154 {
1165 }
1173 /* Don't perform operation if we honor signaling NaNs and
1174 either operand is a NaN. */
1179 /* Don't perform operation if it would raise a division
1180 by zero exception. */
1186 /* If either operand is a NaN, just return it. Otherwise, set up
1187 for floating-point trap; we return an overflow. */
1196 /* Don't constant fold this floating point operation if
1197 the result has overflowed and flag_trapping_math. */
1205 /* Don't constant fold this floating point operation if the
1206 result may dependent upon the run-time rounding mode and
1207 flag_rounding_math is set, or if GCC's software emulation
1208 is unable to accurately represent the result. */
1218 }
1221 {
1222 FIXED_VALUE_TYPE f1;
1223 FIXED_VALUE_TYPE f2;
1224 FIXED_VALUE_TYPE result;
1229 /* The following codes are handled by fixed_arithmetic. */
1231 {
1243 {
1250 }
1255 }
1262 /* Propagate overflow flags. */
1266 }
1269 {
1278 {
1289 mpc_mul);
1303 mpc_div);
1304 /* Fallthru ... */
1310 {
1311 /* Keep this algorithm in sync with
1312 tree-complex.c:expand_complex_div_straight().
1314 Expand complex division to scalars, straightforward algorithm.
1315 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1316 t = br*br + bi*bi
1317 */
1318 tree magsquared
1322 tree t1
1326 tree t2
1333 }
1334 else
1335 {
1336 /* Keep this algorithm in sync with
1337 tree-complex.c:expand_complex_div_wide().
1339 Expand complex division to scalars, modified algorithm to minimize
1340 overflow with wide input ranges. */
1346 {
1347 /* In the TRUE branch, we compute
1348 ratio = br/bi;
1349 div = (br * ratio) + bi;
1350 tr = (ar * ratio) + ai;
1351 ti = (ai * ratio) - ar;
1352 tr = tr / div;
1353 ti = ti / div; */
1364 }
1365 else
1366 {
1367 /* In the FALSE branch, we compute
1368 ratio = d/c;
1369 divisor = (d * ratio) + c;
1370 tr = (b * ratio) + a;
1371 ti = b - (a * ratio);
1372 tr = tr / div;
1373 ti = ti / div; */
1385 }
1386 }
1391 }
1395 }
1399 {
1405 {
1411 /* It is possible that const_binop cannot handle the given
1412 code and return NULL_TREE */
1415 }
1418 }
1420 /* Shifts allow a scalar offset for a vector. */
1423 {
1429 {
1434 /* It is possible that const_binop cannot handle the given
1435 code and return NULL_TREE. */
1438 }
1441 }
1443 }
1445 /* Overload that adds a TYPE parameter to be able to dispatch
1446 to fold_relational_const. */
1448 tree
1450 {
1454 /* ??? Until we make the const_binop worker take the type of the
1455 result as argument put those cases that need it here. */
1457 {
1468 {
1484 {
1490 }
1493 }
1499 {
1524 {
1537 }
1540 }
1543 }
1548 /* 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 {
2918 /* Require equal access sizes, and similar pointer types.
2919 We can have incomplete types for array references of
2920 variable-sized arrays from the Fortran frontend
2921 though. Also verify the types are compatible. */
2929 || (alias_ptr_types_compatible_p
2941 /* TARGET_MEM_REF require equal extra operands. */
2949 /* Operands 2 and 3 may be null.
2950 Compare the array index by value if it is constant first as we
2951 may have different types but same value here. */
2962 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2963 may be NULL when we're called to compare MEM_EXPRs. */
2978 }
2982 {
3000 /* The multiplcation operands are commutative. */
3001 /* FALLTHRU */
3009 /* Otherwise take into account this is a commutative operation. */
3022 }
3026 {
3030 /* If not both CALL_EXPRs are either internal or normal function
3031 functions, then they are not equal. */
3034 {
3035 /* If the CALL_EXPRs call different internal functions, then they
3036 are not equal. */
3039 }
3040 else
3041 {
3042 /* If the CALL_EXPRs call different functions, then they are not
3043 equal. */
3045 flags))
3047 }
3049 {
3053 else
3057 }
3059 /* Now see if all the arguments are the same. */
3060 {
3071 /* If we get here and both argument lists are exhausted
3072 then the CALL_EXPRs are equal. */
3074 }
3077 }
3080 /* Consider __builtin_sqrt equal to sqrt. */
3088 }
3090 #undef OP_SAME
3091 #undef OP_SAME_WITH_NULL
3092 }
3093 \f
3094 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3095 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3097 When in doubt, return 0. */
3099 static int
3101 {
3113 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3114 and see if the inner values are the same. This removes any
3115 signedness comparison, which doesn't matter here. */
3122 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3123 actual comparison operand, ARG0.
3125 First throw away any conversions to wider types
3126 already present in the operands. */
3135 {
3138 /* Make sure shorter operand is extended the right way
3139 to match the longer operand. */
3145 }
3148 }
3149 \f
3150 /* See if ARG is an expression that is either a comparison or is performing
3151 arithmetic on comparisons. The comparisons must only be comparing
3152 two different values, which will be stored in *CVAL1 and *CVAL2; if
3153 they are nonzero it means that some operands have already been found.
3154 No variables may be used anywhere else in the expression except in the
3155 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3156 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3158 If this is true, return 1. Otherwise, return zero. */
3160 static int
3162 {
3166 /* We can handle some of the tcc_expression cases here. */
3176 {
3177 /* If we've already found a CVAL1 or CVAL2, this expression is
3178 two complex to handle. */
3184 }
3187 {
3210 /* First see if we can handle the first operand, then the second. For
3211 the second operand, we know *CVAL1 can't be zero. It must be that
3212 one side of the comparison is each of the values; test for the
3213 case where this isn't true by failing if the two operands
3214 are the same. */
3223 ;
3227 ;
3228 else
3232 ;
3236 ;
3237 else
3244 }
3245 }
3246 \f
3247 /* ARG is a tree that is known to contain just arithmetic operations and
3248 comparisons. Evaluate the operations in the tree substituting NEW0 for
3249 any occurrence of OLD0 as an operand of a comparison and likewise for
3250 NEW1 and OLD1. */
3252 static tree
3255 {
3260 /* We can handle some of the tcc_expression cases here. */
3268 {
3283 {
3302 }
3303 /* Fall through - ??? */
3306 {
3310 /* We need to check both for exact equality and tree equality. The
3311 former will be true if the operand has a side-effect. In that
3312 case, we know the operand occurred exactly once. */
3325 }
3329 }
3330 }
3331 \f
3332 /* Return a tree for the case when the result of an expression is RESULT
3333 converted to TYPE and OMITTED was previously an operand of the expression
3334 but is now not needed (e.g., we folded OMITTED * 0).
3336 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3337 the conversion of RESULT to TYPE. */
3339 tree
3341 {
3344 /* If the resulting operand is an empty statement, just return the omitted
3345 statement casted to void. */
3355 }
3357 /* Return a tree for the case when the result of an expression is RESULT
3358 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3359 of the expression but are now not needed.
3361 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3362 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3363 evaluated before OMITTED2. Otherwise, if neither has side effects,
3364 just do the conversion of RESULT to TYPE. */
3366 tree
3369 {
3378 }
3380 \f
3381 /* Return a simplified tree node for the truth-negation of ARG. This
3382 never alters ARG itself. We assume that ARG is an operation that
3383 returns a truth value (0 or 1).
3385 FIXME: one would think we would fold the result, but it causes
3386 problems with the dominator optimizer. */
3388 static tree
3390 {
3395 /* If this is a comparison, we can simply invert it, except for
3396 floating-point non-equality comparisons, in which case we just
3397 enclose a TRUTH_NOT_EXPR around what we have. */
3400 {
3403 && flag_trapping_math
3414 }
3417 {
3436 /* Here we can invert either operand. We invert the first operand
3437 unless the second operand is a TRUTH_NOT_EXPR in which case our
3438 result is the XOR of the first operand with the inside of the
3439 negation of the second operand. */
3444 else
3467 {
3474 /* A COND_EXPR may have a throw as one operand, which
3475 then has void type. Just leave void operands
3476 as they are. */
3482 }
3494 CASE_CONVERT:
3498 /* ... fall through ... */
3520 }
3521 }
3523 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3524 assume that ARG is an operation that returns a truth value (0 or 1
3525 for scalars, 0 or -1 for vectors). Return the folded expression if
3526 folding is successful. Otherwise, return NULL_TREE. */
3528 static tree
3530 {
3533 ? BIT_NOT_EXPR
3536 }
3538 /* Return a simplified tree node for the truth-negation of ARG. This
3539 never alters ARG itself. We assume that ARG is an operation that
3540 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3542 tree
3544 {
3550 ? BIT_NOT_EXPR
3553 }
3555 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3556 operands are another bit-wise operation with a common input. If so,
3557 distribute the bit operations to save an operation and possibly two if
3558 constants are involved. For example, convert
3559 (A | B) & (A | C) into A | (B & C)
3560 Further simplification will occur if B and C are constants.
3562 If this optimization cannot be done, 0 will be returned. */
3564 static tree
3567 {
3568 tree common;
3578 {
3582 }
3584 {
3588 }
3590 {
3594 }
3596 {
3600 }
3601 else
3609 }
3611 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3612 with code CODE. This optimization is unsafe. */
3613 static tree
3616 {
3620 /* (A / C) +- (B / C) -> (A +- B) / C. */
3630 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3635 {
3647 }
3650 }
3651 \f
3652 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3653 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3655 static tree
3658 {
3662 {
3669 }
3683 }
3685 /* Optimize a bit-field compare.
3687 There are two cases: First is a compare against a constant and the
3688 second is a comparison of two items where the fields are at the same
3689 bit position relative to the start of a chunk (byte, halfword, word)
3690 large enough to contain it. In these cases we can avoid the shift
3691 implicit in bitfield extractions.
3693 For constants, we emit a compare of the shifted constant with the
3694 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3695 compared. For two fields at the same position, we do the ANDs with the
3696 similar mask and compare the result of the ANDs.
3698 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3699 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3700 are the left and right operands of the comparison, respectively.
3702 If the optimization described above can be done, we return the resulting
3703 tree. Otherwise we return zero. */
3705 static tree
3708 {
3711 tree unsigned_type;
3717 tree mask;
3718 tree offset;
3720 /* Get all the information about the extractions being done. If the bit size
3721 if the same as the size of the underlying object, we aren't doing an
3722 extraction at all and so can do nothing. We also don't want to
3723 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3724 then will no longer be able to replace it. */
3732 {
3733 /* If this is not a constant, we can only do something if bit positions,
3734 sizes, and signedness are the same. */
3742 }
3744 /* See if we can find a mode to refer to this field. We should be able to,
3745 but fail if we can't. */
3754 /* Set signed and unsigned types of the precision of this mode for the
3755 shifts below. */
3758 /* Compute the bit position and size for the new reference and our offset
3759 within it. If the new reference is the same size as the original, we
3760 won't optimize anything, so return zero. */
3770 /* Make the mask to be used against the extracted field. */
3777 /* If not comparing with constant, just rework the comparison
3778 and return. */
3782 unsigned_type,
3785 mask),
3788 unsigned_type,
3791 mask));
3793 /* Otherwise, we are handling the constant case. See if the constant is too
3794 big for the field. Warn and return a tree of for 0 (false) if so. We do
3795 this not only for its own sake, but to avoid having to test for this
3796 error case below. If we didn't, we might generate wrong code.
3798 For unsigned fields, the constant shifted right by the field length should
3799 be all zero. For signed fields, the high-order bits should agree with
3800 the sign bit. */
3803 {
3805 {
3809 }
3810 }
3811 else
3812 {
3815 {
3819 }
3820 }
3822 /* Single-bit compares should always be against zero. */
3824 {
3827 }
3829 /* Make a new bitfield reference, shift the constant over the
3830 appropriate number of bits and mask it with the computed mask
3831 (in case this was a signed field). If we changed it, make a new one. */
3838 mask);
3843 }
3844 \f
3845 /* Subroutine for fold_truth_andor_1: decode a field reference.
3847 If EXP is a comparison reference, we return the innermost reference.
3849 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3850 set to the starting bit number.
3852 If the innermost field can be completely contained in a mode-sized
3853 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3855 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3856 otherwise it is not changed.
3858 *PUNSIGNEDP is set to the signedness of the field.
3860 *PMASK is set to the mask used. This is either contained in a
3861 BIT_AND_EXPR or derived from the width of the field.
3863 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3865 Return 0 if this is not a component reference or is one that we can't
3866 do anything with. */
3868 static tree
3873 {
3877 tree unsigned_type;
3880 /* All the optimizations using this function assume integer fields.
3881 There are problems with FP fields since the type_for_size call
3882 below can fail for, e.g., XFmode. */
3886 /* We are interested in the bare arrangement of bits, so strip everything
3887 that doesn't affect the machine mode. However, record the type of the
3888 outermost expression if it may matter below. */
3895 {
3901 }
3910 /* If the number of bits in the reference is the same as the bitsize of
3911 the outer type, then the outer type gives the signedness. Otherwise
3912 (in case of a small bitfield) the signedness is unchanged. */
3916 /* Compute the mask to access the bitfield. */
3925 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3933 }
3935 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3936 bit positions and MASK is SIGNED. */
3938 static int
3940 {
3944 /* If this function returns true when the type of the mask is
3945 UNSIGNED, then there will be errors. In particular see
3946 gcc.c-torture/execute/990326-1.c. There does not appear to be
3947 any documentation paper trail as to why this is so. But the pre
3948 wide-int worked with that restriction and it has been preserved
3949 here. */
3954 }
3956 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3957 represents the sign bit of EXP's type. If EXP represents a sign
3958 or zero extension, also test VAL against the unextended type.
3959 The return value is the (sub)expression whose sign bit is VAL,
3960 or NULL_TREE otherwise. */
3962 tree
3964 {
3966 tree t;
3968 /* Tree EXP must have an integral type. */
3973 /* Tree VAL must be an integer constant. */
3982 /* Handle extension from a narrower type. */
3988 }
3990 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3991 to be evaluated unconditionally. */
3993 static int
3995 {
3996 /* Strip any conversions that don't change the machine mode. */
4005 /* Don't regard global variables as simple. They may be
4006 allocated in ways unknown to the compiler (shared memory,
4007 #pragma weak, etc). */
4010 /* Weakrefs are not safe to be read, since they can be NULL.
4011 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4012 have DECL_WEAK flag set. */
4014 /* Loading a static variable is unduly expensive, but global
4015 registers aren't expensive. */
4017 }
4019 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4020 to be evaluated unconditionally.
4021 I addition to simple_operand_p, we assume that comparisons, conversions,
4022 and logic-not operations are simple, if their operands are simple, too. */
4024 static bool
4026 {
4046 }
4048 \f
4049 /* The following functions are subroutines to fold_range_test and allow it to
4050 try to change a logical combination of comparisons into a range test.
4052 For example, both
4053 X == 2 || X == 3 || X == 4 || X == 5
4054 and
4055 X >= 2 && X <= 5
4056 are converted to
4057 (unsigned) (X - 2) <= 3
4059 We describe each set of comparisons as being either inside or outside
4060 a range, using a variable named like IN_P, and then describe the
4061 range with a lower and upper bound. If one of the bounds is omitted,
4062 it represents either the highest or lowest value of the type.
4064 In the comments below, we represent a range by two numbers in brackets
4065 preceded by a "+" to designate being inside that range, or a "-" to
4066 designate being outside that range, so the condition can be inverted by
4067 flipping the prefix. An omitted bound is represented by a "-". For
4068 example, "- [-, 10]" means being outside the range starting at the lowest
4069 possible value and ending at 10, in other words, being greater than 10.
4070 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4071 always false.
4073 We set up things so that the missing bounds are handled in a consistent
4074 manner so neither a missing bound nor "true" and "false" need to be
4075 handled using a special case. */
4077 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4078 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4079 and UPPER1_P are nonzero if the respective argument is an upper bound
4080 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4081 must be specified for a comparison. ARG1 will be converted to ARG0's
4082 type if both are specified. */
4084 static tree
4087 {
4088 tree tem;
4092 /* If neither arg represents infinity, do the normal operation.
4093 Else, if not a comparison, return infinity. Else handle the special
4094 comparison rules. Note that most of the cases below won't occur, but
4095 are handled for consistency. */
4098 {
4103 }
4108 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4109 for neither. In real maths, we cannot assume open ended ranges are
4110 the same. But, this is computer arithmetic, where numbers are finite.
4111 We can therefore make the transformation of any unbounded range with
4112 the value Z, Z being greater than any representable number. This permits
4113 us to treat unbounded ranges as equal. */
4117 {
4138 }
4141 }
4142 \f
4143 /* Helper routine for make_range. Perform one step for it, return
4144 new expression if the loop should continue or NULL_TREE if it should
4145 stop. */
4147 tree
4151 {
4157 {
4159 /* We can only do something if the range is testing for zero. */
4168 /* We can only do something if the range is testing for zero
4169 and if the second operand is an integer constant. Note that
4170 saying something is "in" the range we make is done by
4171 complementing IN_P since it will set in the initial case of
4172 being not equal to zero; "out" is leaving it alone. */
4179 {
4200 }
4202 /* If this is an unsigned comparison, we also know that EXP is
4203 greater than or equal to zero. We base the range tests we make
4204 on that fact, so we record it here so we can parse existing
4205 range tests. We test arg0_type since often the return type
4206 of, e.g. EQ_EXPR, is boolean. */
4208 {
4212 NULL_TREE))
4217 /* If the high bound is missing, but we have a nonzero low
4218 bound, reverse the range so it goes from zero to the low bound
4219 minus 1. */
4221 {
4226 }
4227 }
4235 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4236 low and high are non-NULL, then normalize will DTRT. */
4239 {
4244 }
4246 /* (-x) IN [a,b] -> x in [-b, -a] */
4258 /* ~ X -> -X - 1 */
4267 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4268 move a constant to the other side. */
4273 /* If EXP is signed, any overflow in the computation is undefined,
4274 so we don't worry about it so long as our computations on
4275 the bounds don't overflow. For unsigned, overflow is defined
4276 and this is exactly the right thing. */
4288 normalize:
4289 /* Check for an unsigned range which has wrapped around the maximum
4290 value thus making n_high < n_low, and normalize it. */
4292 {
4298 /* If the range is of the form +/- [ x+1, x ], we won't
4299 be able to normalize it. But then, it represents the
4300 whole range or the empty set, so make it
4301 +/- [ -, - ]. */
4305 else
4307 }
4308 else
4316 CASE_CONVERT:
4334 /* If we're converting arg0 from an unsigned type, to exp,
4335 a signed type, we will be doing the comparison as unsigned.
4336 The tests above have already verified that LOW and HIGH
4337 are both positive.
4339 So we have to ensure that we will handle large unsigned
4340 values the same way that the current signed bounds treat
4341 negative values. */
4344 {
4345 tree high_positive;
4346 tree equiv_type;
4347 /* For fixed-point modes, we need to pass the saturating flag
4348 as the 2nd parameter. */
4350 equiv_type
4353 else
4354 equiv_type
4357 /* A range without an upper bound is, naturally, unbounded.
4358 Since convert would have cropped a very large value, use
4359 the max value for the destination type. */
4360 high_positive
4367 high_positive),
4370 /* If the low bound is specified, "and" the range with the
4371 range for which the original unsigned value will be
4372 positive. */
4374 {
4377 integer_zero_node),
4378 high_positive))
4382 }
4383 else
4384 {
4385 /* Otherwise, "or" the range with the range of the input
4386 that will be interpreted as negative. */
4389 integer_zero_node),
4390 high_positive))
4394 }
4395 }
4404 }
4405 }
4407 /* Given EXP, a logical expression, set the range it is testing into
4408 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4409 actually being tested. *PLOW and *PHIGH will be made of the same
4410 type as the returned expression. If EXP is not a comparison, we
4411 will most likely not be returning a useful value and range. Set
4412 *STRICT_OVERFLOW_P to true if the return value is only valid
4413 because signed overflow is undefined; otherwise, do not change
4414 *STRICT_OVERFLOW_P. */
4416 tree
4419 {
4427 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4428 and see if we can refine the range. Some of the cases below may not
4429 happen, but it doesn't seem worth worrying about this. We "continue"
4430 the outer loop when we've changed something; otherwise we "break"
4431 the switch, which will "break" the while. */
4437 {
4443 {
4451 }
4460 }
4462 /* If EXP is a constant, we can evaluate whether this is true or false. */
4464 {
4471 }
4475 }
4476 \f
4477 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4478 type, TYPE, return an expression to test if EXP is in (or out of, depending
4479 on IN_P) the range. Return 0 if the test couldn't be created. */
4481 tree
4484 {
4487 /* Disable this optimization for function pointer expressions
4488 on targets that require function pointer canonicalization. */
4495 {
4501 }
4519 {
4521 {
4525 }
4527 }
4529 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4531 {
4535 {
4537 {
4540 etype
4542 else
4545 }
4548 }
4549 }
4551 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4552 This requires wrap-around arithmetics for the type of the expression.
4553 First make sure that arithmetics in this type is valid, then make sure
4554 that it wraps around. */
4560 {
4563 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4564 for the type in question, as we rely on this here. */
4574 else
4576 }
4586 {
4588 {
4593 }
4595 }
4603 }
4604 \f
4605 /* Return the predecessor of VAL in its type, handling the infinite case. */
4607 static tree
4609 {
4615 else
4618 }
4620 /* Return the successor of VAL in its type, handling the infinite case. */
4622 static tree
4624 {
4630 else
4633 }
4635 /* Given two ranges, see if we can merge them into one. Return 1 if we
4636 can, 0 if we can't. Set the output range into the specified parameters. */
4638 bool
4641 {
4645 tree tem;
4655 /* Make range 0 be the range that starts first, or ends last if they
4656 start at the same value. Swap them if it isn't. */
4659 || (lowequal
4662 {
4666 }
4668 /* Now flag two cases, whether the ranges are disjoint or whether the
4669 second range is totally subsumed in the first. Note that the tests
4670 below are simplified by the ones above. */
4676 /* We now have four cases, depending on whether we are including or
4677 excluding the two ranges. */
4679 {
4680 /* If they don't overlap, the result is false. If the second range
4681 is a subset it is the result. Otherwise, the range is from the start
4682 of the second to the end of the first. */
4687 else
4689 }
4692 {
4693 /* If they don't overlap, the result is the first range. If they are
4694 equal, the result is false. If the second range is a subset of the
4695 first, and the ranges begin at the same place, we go from just after
4696 the end of the second range to the end of the first. If the second
4697 range is not a subset of the first, or if it is a subset and both
4698 ranges end at the same place, the range starts at the start of the
4699 first range and ends just before the second range.
4700 Otherwise, we can't describe this as a single range. */
4706 {
4711 {
4712 /* We are in the weird situation where high0 > high1 but
4713 high1 has no successor. Punt. */
4715 }
4716 }
4718 {
4723 {
4724 /* low0 < low1 but low1 has no predecessor. Punt. */
4726 }
4727 }
4728 else
4730 }
4733 {
4734 /* If they don't overlap, the result is the second range. If the second
4735 is a subset of the first, the result is false. Otherwise,
4736 the range starts just after the first range and ends at the
4737 end of the second. */
4742 else
4743 {
4748 {
4749 /* high1 > high0 but high0 has no successor. Punt. */
4751 }
4752 }
4753 }
4755 else
4756 {
4757 /* The case where we are excluding both ranges. Here the complex case
4758 is if they don't overlap. In that case, the only time we have a
4759 range is if they are adjacent. If the second is a subset of the
4760 first, the result is the first. Otherwise, the range to exclude
4761 starts at the beginning of the first range and ends at the end of the
4762 second. */
4764 {
4769 else
4770 {
4771 /* Canonicalize - [min, x] into - [-, x]. */
4774 {
4779 /* FALLTHROUGH */
4792 }
4794 /* Canonicalize - [x, max] into - [x, -]. */
4797 {
4802 /* FALLTHROUGH */
4818 }
4820 /* The ranges might be also adjacent between the maximum and
4821 minimum values of the given type. For
4822 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4823 return + [x + 1, y - 1]. */
4825 {
4832 }
4833 else
4835 }
4836 }
4839 else
4841 }
4845 }
4846 \f
4848 /* Subroutine of fold, looking inside expressions of the form
4849 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4850 of the COND_EXPR. This function is being used also to optimize
4851 A op B ? C : A, by reversing the comparison first.
4853 Return a folded expression whose code is not a COND_EXPR
4854 anymore, or NULL_TREE if no folding opportunity is found. */
4856 static tree
4859 {
4864 tree tem;
4869 /* If we have A op 0 ? A : -A, consider applying the following
4870 transformations:
4872 A == 0? A : -A same as -A
4873 A != 0? A : -A same as A
4874 A >= 0? A : -A same as abs (A)
4875 A > 0? A : -A same as abs (A)
4876 A <= 0? A : -A same as -abs (A)
4877 A < 0? A : -A same as -abs (A)
4879 None of these transformations work for modes with signed
4880 zeros. If A is +/-0, the first two transformations will
4881 change the sign of the result (from +0 to -0, or vice
4882 versa). The last four will fix the sign of the result,
4883 even though the original expressions could be positive or
4884 negative, depending on the sign of A.
4886 Note that all these transformations are correct if A is
4887 NaN, since the two alternatives (A and -A) are also NaNs. */
4894 /* In the case that A is of the form X-Y, '-A' (arg2) may
4895 have already been folded to Y-X, check for that. */
4903 {
4917 /* Fall through. */
4939 }
4941 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4942 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4943 both transformations are correct when A is NaN: A != 0
4944 is then true, and A == 0 is false. */
4948 {
4953 }
4955 /* Try some transformations of A op B ? A : B.
4957 A == B? A : B same as B
4958 A != B? A : B same as A
4959 A >= B? A : B same as max (A, B)
4960 A > B? A : B same as max (B, A)
4961 A <= B? A : B same as min (A, B)
4962 A < B? A : B same as min (B, A)
4964 As above, these transformations don't work in the presence
4965 of signed zeros. For example, if A and B are zeros of
4966 opposite sign, the first two transformations will change
4967 the sign of the result. In the last four, the original
4968 expressions give different results for (A=+0, B=-0) and
4969 (A=-0, B=+0), but the transformed expressions do not.
4971 The first two transformations are correct if either A or B
4972 is a NaN. In the first transformation, the condition will
4973 be false, and B will indeed be chosen. In the case of the
4974 second transformation, the condition A != B will be true,
4975 and A will be chosen.
4977 The conversions to max() and min() are not correct if B is
4978 a number and A is not. The conditions in the original
4979 expressions will be false, so all four give B. The min()
4980 and max() versions would give a NaN instead. */
4983 /* Avoid these transformations if the COND_EXPR may be used
4984 as an lvalue in the C++ front-end. PR c++/19199. */
4985 && (in_gimple_form
4991 {
4996 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4998 {
5002 }
5005 {
5014 /* In C++ a ?: expression can be an lvalue, so put the
5015 operand which will be used if they are equal first
5016 so that we can convert this back to the
5017 corresponding COND_EXPR. */
5019 {
5028 }
5035 {
5044 }
5059 }
5060 }
5062 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5063 we might still be able to simplify this. For example,
5064 if C1 is one less or one more than C2, this might have started
5065 out as a MIN or MAX and been transformed by this function.
5066 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5072 {
5076 /* We can replace A with C1 in this case. */
5081 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5082 MIN_EXPR, to preserve the signedness of the comparison. */
5084 OEP_ONLY_CONST)
5088 OEP_ONLY_CONST))
5089 {
5092 arg2));
5095 }
5099 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5100 as above. */
5102 OEP_ONLY_CONST)
5106 OEP_ONLY_CONST))
5107 {
5110 arg2));
5113 }
5117 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5118 MAX_EXPR, to preserve the signedness of the comparison. */
5120 OEP_ONLY_CONST)
5124 OEP_ONLY_CONST))
5125 {
5128 arg2));
5130 }
5134 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5136 OEP_ONLY_CONST)
5140 OEP_ONLY_CONST))
5141 {
5144 arg2));
5146 }
5152 }
5155 }
5158 \f
5159 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5160 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5161 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5162 false) >= 2)
5163 #endif
5165 /* EXP is some logical combination of boolean tests. See if we can
5166 merge it into some range test. Return the new tree if so. */
5168 static tree
5171 {
5187 /* If this is an OR operation, invert both sides; we will invert
5188 again at the end. */
5192 /* If both expressions are the same, if we can merge the ranges, and we
5193 can build the range test, return it or it inverted. If one of the
5194 ranges is always true or always false, consider it to be the same
5195 expression as the other. */
5203 {
5207 }
5209 /* On machines where the branch cost is expensive, if this is a
5210 short-circuited branch and the underlying object on both sides
5211 is the same, make a non-short-circuit operation. */
5217 {
5218 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5219 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5220 which cases we can't do this. */
5228 {
5237 {
5240 WARN_STRICT_OVERFLOW_COMPARISON);
5244 }
5245 }
5246 }
5249 }
5250 \f
5251 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5252 bit value. Arrange things so the extra bits will be set to zero if and
5253 only if C is signed-extended to its full width. If MASK is nonzero,
5254 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5256 static tree
5258 {
5261 tree temp;
5266 /* We work by getting just the sign bit into the low-order bit, then
5267 into the high-order bit, then sign-extend. We then XOR that value
5268 with C. */
5271 /* We must use a signed type in order to get an arithmetic right shift.
5272 However, we must also avoid introducing accidental overflows, so that
5273 a subsequent call to integer_zerop will work. Hence we must
5274 do the type conversion here. At this point, the constant is either
5275 zero or one, and the conversion to a signed type can never overflow.
5276 We could get an overflow if this conversion is done anywhere else. */
5285 /* If necessary, convert the type back to match the type of C. */
5290 }
5291 \f
5292 /* For an expression that has the form
5293 (A && B) || ~B
5294 or
5295 (A || B) && ~B,
5296 we can drop one of the inner expressions and simplify to
5297 A || ~B
5298 or
5299 A && ~B
5300 LOC is the location of the resulting expression. OP is the inner
5301 logical operation; the left-hand side in the examples above, while CMPOP
5302 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5303 removing a condition that guards another, as in
5304 (A != NULL && A->...) || A == NULL
5305 which we must not transform. If RHS_ONLY is true, only eliminate the
5306 right-most operand of the inner logical operation. */
5308 static tree
5311 {
5329 {
5332 {
5335 }
5336 }
5338 {
5341 {
5344 }
5345 }
5360 }
5362 /* Find ways of folding logical expressions of LHS and RHS:
5363 Try to merge two comparisons to the same innermost item.
5364 Look for range tests like "ch >= '0' && ch <= '9'".
5365 Look for combinations of simple terms on machines with expensive branches
5366 and evaluate the RHS unconditionally.
5368 For example, if we have p->a == 2 && p->b == 4 and we can make an
5369 object large enough to span both A and B, we can do this with a comparison
5370 against the object ANDed with the a mask.
5372 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5373 operations to do this with one comparison.
5375 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5376 function and the one above.
5378 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5379 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5381 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5382 two operands.
5384 We return the simplified tree or 0 if no optimization is possible. */
5386 static tree
5389 {
5390 /* If this is the "or" of two comparisons, we can do something if
5391 the comparisons are NE_EXPR. If this is the "and", we can do something
5392 if the comparisons are EQ_EXPR. I.e.,
5393 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5395 WANTED_CODE is this operation code. For single bit fields, we can
5396 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5397 comparison for one-bit fields. */
5417 /* Start by getting the comparison codes. Fail if anything is volatile.
5418 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5419 it were surrounded with a NE_EXPR. */
5428 {
5432 }
5435 {
5439 }
5450 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5453 {
5456 {
5461 }
5464 {
5470 }
5471 }
5476 /* If the RHS can be evaluated unconditionally and its operands are
5477 simple, it wins to evaluate the RHS unconditionally on machines
5478 with expensive branches. In this case, this isn't a comparison
5479 that can be merged. */
5486 {
5487 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5498 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5508 }
5510 /* See if the comparisons can be merged. Then get all the parameters for
5511 each side. */
5535 /* It must be true that the inner operation on the lhs of each
5536 comparison must be the same if we are to be able to do anything.
5537 Then see if we have constants. If not, the same must be true for
5538 the rhs's. */
5549 else
5552 /* If either comparison code is not correct for our logical operation,
5553 fail. However, we can convert a one-bit comparison against zero into
5554 the opposite comparison against that bit being set in the field. */
5558 {
5560 {
5561 /* Make the left operand unsigned, since we are only interested
5562 in the value of one bit. Otherwise we are doing the wrong
5563 thing below. */
5566 }
5567 else
5569 }
5571 /* This is analogous to the code for l_const above. */
5573 {
5575 {
5578 }
5579 else
5581 }
5583 /* See if we can find a mode that contains both fields being compared on
5584 the left. If we can't, fail. Otherwise, update all constants and masks
5585 to be relative to a field of that size. */
5590 volatilep);
5600 {
5603 }
5611 {
5618 {
5622 }
5623 }
5625 {
5632 {
5636 }
5637 }
5639 /* If the right sides are not constant, do the same for it. Also,
5640 disallow this optimization if a size or signedness mismatch occurs
5641 between the left and right sides. */
5643 {
5646 /* Make sure the two fields on the right
5647 correspond to the left without being swapped. */
5655 volatilep);
5665 {
5668 }
5677 /* Make a mask that corresponds to both fields being compared.
5678 Do this for both items being compared. If the operands are the
5679 same size and the bits being compared are in the same position
5680 then we can do this by masking both and comparing the masked
5681 results. */
5685 {
5697 }
5699 /* There is still another way we can do something: If both pairs of
5700 fields being compared are adjacent, we may be able to make a wider
5701 field containing them both.
5703 Note that we still must mask the lhs/rhs expressions. Furthermore,
5704 the mask must be shifted to account for the shift done by
5705 make_bit_field_ref. */
5710 {
5711 tree type;
5725 /* Convert to the smaller type before masking out unwanted bits. */
5728 {
5730 {
5734 }
5736 {
5740 }
5741 }
5750 }
5753 }
5755 /* Handle the case of comparisons with constants. If there is something in
5756 common between the masks, those bits of the constants must be the same.
5757 If not, the condition is always false. Test for this to avoid generating
5758 incorrect code below. */
5763 {
5765 {
5768 }
5769 else
5770 {
5773 }
5774 }
5776 /* Construct the expression we will return. First get the component
5777 reference we will make. Unless the mask is all ones the width of
5778 that field, perform the mask operation. Then compare with the
5779 merged constant. */
5789 }
5790 \f
5791 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5792 constant. */
5794 static tree
5797 {
5800 tree comp_const;
5801 tree minmax_const;
5803 tree inner;
5814 /* If something does not permit us to optimize, return the original tree. */
5822 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5823 and GT_EXPR, doing the rest with recursive calls using logical
5824 simplifications. */
5826 {
5828 {
5829 tree tem
5836 }
5839 return
5841 optimize_minmax_comparison
5843 optimize_minmax_comparison
5848 /* MAX (X, 0) == 0 -> X <= 0 */
5852 /* MAX (X, 0) == 5 -> X == 5 */
5856 /* MAX (X, 0) == -1 -> false */
5860 /* MIN (X, 0) == 0 -> X >= 0 */
5864 /* MIN (X, 0) == 5 -> false */
5867 else
5868 /* MIN (X, 0) == -1 -> X == -1 */
5873 /* MAX (X, 0) > 0 -> X > 0
5874 MAX (X, 0) > 5 -> X > 5 */
5878 /* MAX (X, 0) > -1 -> true */
5882 /* MIN (X, 0) > 0 -> false
5883 MIN (X, 0) > 5 -> false */
5886 else
5887 /* MIN (X, 0) > -1 -> X > -1 */
5892 }
5893 }
5894 \f
5895 /* T is an integer expression that is being multiplied, divided, or taken a
5896 modulus (CODE says which and what kind of divide or modulus) by a
5897 constant C. See if we can eliminate that operation by folding it with
5898 other operations already in T. WIDE_TYPE, if non-null, is a type that
5899 should be used for the computation if wider than our type.
5901 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5902 (X * 2) + (Y * 4). We must, however, be assured that either the original
5903 expression would not overflow or that overflow is undefined for the type
5904 in the language in question.
5906 If we return a non-null expression, it is an equivalent form of the
5907 original computation, but need not be in the original type.
5909 We set *STRICT_OVERFLOW_P to true if the return values depends on
5910 signed overflow being undefined. Otherwise we do not change
5911 *STRICT_OVERFLOW_P. */
5913 static tree
5916 {
5917 /* To avoid exponential search depth, refuse to allow recursion past
5918 three levels. Beyond that (1) it's highly unlikely that we'll find
5919 something interesting and (2) we've probably processed it before
5920 when we built the inner expression. */
5923 tree ret;
5928 depth++;
5930 depth--;
5933 }
5935 static tree
5938 {
5949 /* Don't deal with constants of zero here; they confuse the code below. */
5959 /* Note that we need not handle conditional operations here since fold
5960 already handles those cases. So just do arithmetic here. */
5962 {
5964 /* For a constant, we can always simplify if we are a multiply
5965 or (for divide and modulus) if it is a multiple of our constant. */
5973 /* If op0 is an expression ... */
5979 /* ... and has wrapping overflow, and its type is smaller
5980 than ctype, then we cannot pass through as widening. */
5985 /* ... or this is a truncation (t is narrower than op0),
5986 then we cannot pass through this narrowing. */
5989 /* ... or signedness changes for division or modulus,
5990 then we cannot pass through this conversion. */
5994 /* ... or has undefined overflow while the converted to
5995 type has not, we cannot do the operation in the inner type
5996 as that would introduce undefined overflow. */
6002 /* Pass the constant down and see if we can make a simplification. If
6003 we can, replace this expression with the inner simplification for
6004 possible later conversion to our or some other type. */
6009 code == MULT_EXPR
6011 strict_overflow_p))))
6016 /* If widening the type changes it from signed to unsigned, then we
6017 must avoid building ABS_EXPR itself as unsigned. */
6019 {
6023 {
6026 }
6028 }
6029 /* If the constant is negative, we cannot simplify this. */
6032 /* FALLTHROUGH */
6034 /* For division and modulus, type can't be unsigned, as e.g.
6035 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6036 For signed types, even with wrapping overflow, this is fine. */
6045 /* If widening the type changes the signedness, then we can't perform
6046 this optimization as that changes the result. */
6050 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6056 {
6063 }
6067 /* If the second operand is constant, this is a multiplication
6068 or floor division, by a power of two, so we can treat it that
6069 way unless the multiplier or divisor overflows. Signed
6070 left-shift overflow is implementation-defined rather than
6071 undefined in C90, so do not convert signed left shift into
6072 multiplication. */
6075 /* const_binop may not detect overflow correctly,
6076 so check for it explicitly here. */
6080 size_one_node,
6081 op1)))
6085 ctype,
6087 t1),
6092 /* See if we can eliminate the operation on both sides. If we can, we
6093 can return a new PLUS or MINUS. If we can't, the only remaining
6094 cases where we can do anything are if the second operand is a
6095 constant. */
6101 /* If not multiplication, we can only do this if both operands
6102 are divisible by c. */
6105 {
6110 }
6112 /* If this was a subtraction, negate OP1 and set it to be an addition.
6113 This simplifies the logic below. */
6115 {
6117 /* If OP1 was not easily negatable, the constant may be OP0. */
6119 {
6122 }
6123 }
6128 /* If either OP1 or C are negative, this optimization is not safe for
6129 some of the division and remainder types while for others we need
6130 to change the code. */
6132 {
6140 }
6142 /* If it's a multiply or a division/modulus operation of a multiple
6143 of our constant, do the operation and verify it doesn't overflow. */
6146 {
6149 /* We allow the constant to overflow with wrapping semantics. */
6153 }
6154 else
6157 /* If we have an unsigned type, we cannot widen the operation since it
6158 will change the result if the original computation overflowed. */
6162 /* If we were able to eliminate our operation from the first side,
6163 apply our operation to the second side and reform the PLUS. */
6167 /* The last case is if we are a multiply. In that case, we can
6168 apply the distributive law to commute the multiply and addition
6169 if the multiplication of the constants doesn't overflow
6170 and overflow is defined. With undefined overflow
6171 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6177 op1);
6182 /* We have a special case here if we are doing something like
6183 (C * 8) % 4 since we know that's zero. */
6186 /* If the multiplication can overflow we cannot optimize this. */
6190 {
6193 }
6195 /* ... fall through ... */
6199 /* If we can extract our operation from the LHS, do so and return a
6200 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6201 do something only if the second operand is a constant. */
6215 /* If these are the same operation types, we can associate them
6216 assuming no overflow. */
6218 {
6230 }
6232 /* If these operations "cancel" each other, we have the main
6233 optimizations of this pass, which occur when either constant is a
6234 multiple of the other, in which case we replace this with either an
6235 operation or CODE or TCODE.
6237 If we have an unsigned type, we cannot do this since it will change
6238 the result if the original computation overflowed. */
6245 {
6247 {
6254 }
6256 {
6263 }
6264 }
6269 }
6272 }
6273 \f
6274 /* Return a node which has the indicated constant VALUE (either 0 or
6275 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6276 and is of the indicated TYPE. */
6278 tree
6280 {
6289 else
6291 }
6294 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6295 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6296 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6297 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6298 COND is the first argument to CODE; otherwise (as in the example
6299 given here), it is the second argument. TYPE is the type of the
6300 original expression. Return NULL_TREE if no simplification is
6301 possible. */
6303 static tree
6308 {
6318 {
6322 /* If this operand throws an expression, then it does not make
6323 sense to try to perform a logical or arithmetic operation
6324 involving it. */
6329 }
6330 else
6331 {
6336 }
6341 /* This transformation is only worthwhile if we don't have to wrap ARG
6342 in a SAVE_EXPR and the operation can be simplified without recursing
6343 on at least one of the branches once its pushed inside the COND_EXPR. */
6352 {
6356 else
6358 }
6360 {
6364 else
6366 }
6368 /* Check that we have simplified at least one of the branches. */
6373 }
6375 \f
6376 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6378 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6379 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6380 ADDEND is the same as X.
6382 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6383 and finite. The problematic cases are when X is zero, and its mode
6384 has signed zeros. In the case of rounding towards -infinity,
6385 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6386 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6388 bool
6390 {
6394 /* Don't allow the fold with -fsignaling-nans. */
6398 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6402 /* In a vector or complex, we would need to check the sign of all zeros. */
6406 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6410 /* The mode has signed zeros, and we have to honor their sign.
6411 In this situation, there is only one case we can return true for.
6412 X - 0 is the same as X unless rounding towards -infinity is
6413 supported. */
6415 }
6417 /* Subroutine of fold() that optimizes comparisons of a division by
6418 a nonzero integer constant against an integer constant, i.e.
6419 X/C1 op C2.
6421 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6422 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6423 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6425 The function returns the constant folded tree if a simplification
6426 can be made, and NULL_TREE otherwise. */
6428 static tree
6431 {
6439 /* We have to do this the hard way to detect unsigned overflow.
6440 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6446 {
6451 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6455 }
6457 {
6461 {
6480 }
6481 }
6482 else
6483 {
6484 /* A negative divisor reverses the relational operators. */
6490 {
6509 }
6510 }
6513 {
6534 {
6537 }
6542 {
6545 }
6550 {
6553 }
6558 {
6561 }
6566 }
6569 }
6572 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6573 equality/inequality test, then return a simplified form of the test
6574 using a sign testing. Otherwise return NULL. TYPE is the desired
6575 result type. */
6577 static tree
6580 tree result_type)
6581 {
6582 /* If this is testing a single bit, we can optimize the test. */
6586 {
6587 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6588 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6592 /* This is only a win if casting to a signed type is cheap,
6593 i.e. when arg00's type is not a partial mode. */
6596 {
6599 result_type,
6602 }
6603 }
6606 }
6608 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6609 equality/inequality test, then return a simplified form of
6610 the test using shifts and logical operations. Otherwise return
6611 NULL. TYPE is the desired result type. */
6613 tree
6616 {
6617 /* If this is testing a single bit, we can optimize the test. */
6621 {
6630 /* First, see if we can fold the single bit test into a sign-bit
6631 test. */
6633 result_type);
6637 /* Otherwise we have (A & C) != 0 where C is a single bit,
6638 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6639 Similarly for (A & C) == 0. */
6641 /* If INNER is a right shift of a constant and it plus BITNUM does
6642 not overflow, adjust BITNUM and INNER. */
6648 {
6651 }
6653 /* If we are going to be able to omit the AND below, we must do our
6654 operations as unsigned. If we must use the AND, we have a choice.
6655 Normally unsigned is faster, but for some machines signed is. */
6656 #ifdef LOAD_EXTEND_OP
6659 #else
6661 #endif
6677 /* Put the AND last so it can combine with more things. */
6680 /* Make sure to return the proper type. */
6684 }
6686 }
6688 /* Check whether we are allowed to reorder operands arg0 and arg1,
6689 such that the evaluation of arg1 occurs before arg0. */
6691 static bool
6693 {
6700 }
6702 /* Test whether it is preferable two swap two operands, ARG0 and
6703 ARG1, for example because ARG0 is an integer constant and ARG1
6704 isn't. If REORDER is true, only recommend swapping if we can
6705 evaluate the operands in reverse order. */
6707 bool
6709 {
6727 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6728 for commutative and comparison operators. Ensuring a canonical
6729 form allows the optimizers to find additional redundancies without
6730 having to explicitly check for both orderings. */
6736 /* Put SSA_NAMEs last. */
6742 /* Put variables last. */
6749 }
6751 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6752 ARG0 is extended to a wider type. */
6754 static tree
6757 {
6759 tree arg1_unw;
6768 /* Disable this optimization if we're casting a function pointer
6769 type on targets that require function pointer canonicalization. */
6780 /* If possible, express the comparison in the shorter mode. */
6800 /* If we are comparing with the integer that does not fit into the range
6801 of the shorter type, the result is known. */
6812 {
6839 }
6842 }
6844 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6845 ARG0 just the signedness is changed. */
6847 static tree
6850 {
6851 tree arg0_inner;
6861 /* Disable this optimization if we're casting a function pointer
6862 type on targets that require function pointer canonicalization. */
6887 else
6891 }
6894 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6895 means A >= Y && A != MAX, but in this case we know that
6896 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6898 static tree
6900 {
6907 else
6916 {
6919 }
6921 {
6924 }
6925 else
6932 {
6933 /* Convert the pointer types into integer before taking the difference. */
6937 }
6938 else
6945 }
6947 /* Fold a sum or difference of at least one multiplication.
6948 Returns the folded tree or NULL if no simplification could be made. */
6950 static tree
6953 {
6957 /* (A * C) +- (B * C) -> (A+-B) * C.
6958 (A * C) +- A -> A * (C+-1).
6959 We are most concerned about the case where C is a constant,
6960 but other combinations show up during loop reduction. Since
6961 it is not difficult, try all four possibilities. */
6964 {
6967 }
6969 {
6972 }
6973 else
6974 {
6975 /* We cannot generate constant 1 for fract. */
6980 }
6982 {
6985 }
6987 {
6989 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6990 the purpose of this canonicalization. */
6994 {
6997 }
6998 else
7000 }
7001 else
7002 {
7003 /* We cannot generate constant 1 for fract. */
7008 }
7020 /* No identical multiplicands; see if we can find a common
7021 power-of-two factor in non-power-of-two multiplies. This
7022 can help in multi-dimensional array access. */
7025 {
7028 tree maybe_same;
7032 /* Move min of absolute values to int11. */
7034 {
7039 }
7040 else
7044 /* The remainder should not be a constant, otherwise we
7045 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7046 increased the number of multiplications necessary. */
7048 {
7056 }
7057 }
7067 }
7069 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7070 specified by EXPR into the buffer PTR of length LEN bytes.
7071 Return the number of bytes placed in the buffer, or zero
7072 upon failure. */
7074 static int
7076 {
7090 {
7092 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7093 number of bytes. */
7097 {
7104 else
7106 }
7107 else
7112 }
7114 }
7117 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7118 specified by EXPR into the buffer PTR of length LEN bytes.
7119 Return the number of bytes placed in the buffer, or zero
7120 upon failure. */
7122 static int
7124 {
7128 FIXED_VALUE_TYPE value;
7144 }
7147 /* Subroutine of native_encode_expr. Encode the REAL_CST
7148 specified by EXPR into the buffer PTR of length LEN bytes.
7149 Return the number of bytes placed in the buffer, or zero
7150 upon failure. */
7152 static int
7154 {
7160 /* There are always 32 bits in each long, no matter the size of
7161 the hosts long. We handle floating point representations with
7162 up to 192 bits. */
7176 {
7181 {
7188 else
7190 }
7191 else
7197 }
7199 }
7201 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7202 specified by EXPR into the buffer PTR of length LEN bytes.
7203 Return the number of bytes placed in the buffer, or zero
7204 upon failure. */
7206 static int
7208 {
7210 tree part;
7225 }
7228 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7229 specified by EXPR into the buffer PTR of length LEN bytes.
7230 Return the number of bytes placed in the buffer, or zero
7231 upon failure. */
7233 static int
7235 {
7245 {
7247 {
7250 }
7261 }
7263 }
7266 /* Subroutine of native_encode_expr. Encode the STRING_CST
7267 specified by EXPR into the buffer PTR of length LEN bytes.
7268 Return the number of bytes placed in the buffer, or zero
7269 upon failure. */
7271 static int
7273 {
7275 HOST_WIDE_INT total_bytes;
7289 {
7292 {
7295 }
7298 }
7299 else
7302 }
7305 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7306 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7307 buffer PTR of length LEN bytes. If OFF is not -1 then start
7308 the encoding at byte offset OFF and encode at most LEN bytes.
7309 Return the number of bytes placed in the buffer, or zero upon failure. */
7311 int
7313 {
7315 {
7336 }
7337 }
7340 /* Subroutine of native_interpret_expr. Interpret the contents of
7341 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7342 If the buffer cannot be interpreted, return NULL_TREE. */
7344 static tree
7346 {
7356 }
7359 /* Subroutine of native_interpret_expr. Interpret the contents of
7360 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7361 If the buffer cannot be interpreted, return NULL_TREE. */
7363 static tree
7365 {
7367 double_int result;
7368 FIXED_VALUE_TYPE fixed_value;
7378 }
7381 /* Subroutine of native_interpret_expr. Interpret the contents of
7382 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7383 If the buffer cannot be interpreted, return NULL_TREE. */
7385 static tree
7387 {
7392 /* There are always 32 bits in each long, no matter the size of
7393 the hosts long. We handle floating point representations with
7394 up to 192 bits. */
7395 REAL_VALUE_TYPE r;
7406 {
7409 {
7416 else
7418 }
7419 else
7424 }
7428 }
7431 /* Subroutine of native_interpret_expr. Interpret the contents of
7432 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7433 If the buffer cannot be interpreted, return NULL_TREE. */
7435 static tree
7437 {
7452 }
7455 /* Subroutine of native_interpret_expr. Interpret the contents of
7456 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7457 If the buffer cannot be interpreted, return NULL_TREE. */
7459 static tree
7461 {
7474 {
7479 }
7481 }
7484 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7485 the buffer PTR of length LEN as a constant of type TYPE. For
7486 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7487 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7488 return NULL_TREE. */
7490 tree
7492 {
7494 {
7516 }
7517 }
7519 /* Returns true if we can interpret the contents of a native encoding
7520 as TYPE. */
7522 static bool
7524 {
7526 {
7539 }
7540 }
7542 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7543 TYPE at compile-time. If we're unable to perform the conversion
7544 return NULL_TREE. */
7546 static tree
7548 {
7549 /* We support up to 512-bit values (for V8DFmode). */
7553 /* Check that the host and target are sane. */
7562 }
7564 /* Build an expression for the address of T. Folds away INDIRECT_REF
7565 to avoid confusing the gimplify process. */
7567 tree
7569 {
7570 /* The size of the object is not relevant when talking about its address. */
7575 {
7580 }
7590 {
7595 }
7596 else
7600 }
7602 /* Build an expression for the address of T. */
7604 tree
7606 {
7610 }
7612 /* Fold a unary expression of code CODE and type TYPE with operand
7613 OP0. Return the folded expression if folding is successful.
7614 Otherwise, return NULL_TREE. */
7616 tree
7618 {
7619 tree tem;
7620 tree arg0;
7628 {
7631 {
7632 /* Don't use STRIP_NOPS, because signedness of argument type
7633 matters. */
7635 }
7636 else
7637 {
7638 /* Strip any conversions that don't change the mode. This
7639 is safe for every expression, except for a comparison
7640 expression because its signedness is derived from its
7641 operands.
7643 Note that this is done as an internal manipulation within
7644 the constant folder, in order to find the simplest
7645 representation of the arguments so that their form can be
7646 studied. In any cases, the appropriate type conversions
7647 should be put back in the tree that will get out of the
7648 constant folder. */
7650 }
7653 {
7656 {
7660 }
7661 }
7662 }
7669 {
7676 {
7690 /* If this was a conversion, and all we did was to move into
7691 inside the COND_EXPR, bring it back out. But leave it if
7692 it is a conversion from integer to integer and the
7693 result precision is no wider than a word since such a
7694 conversion is cheap and may be optimized away by combine,
7695 while it couldn't if it were outside the COND_EXPR. Then return
7696 so we don't get into an infinite recursion loop taking the
7697 conversion out and then back in. */
7709 && (INTEGRAL_TYPE_P
7722 }
7723 }
7726 {
7732 CASE_CONVERT:
7736 {
7737 /* If we have (type) (a CMP b) and type is an integral type, return
7738 new expression involving the new type. Canonicalize
7739 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7740 non-integral type.
7741 Do not fold the result as that would not simplify further, also
7742 folding again results in recursions. */
7752 }
7754 /* Handle (T *)&A.B.C for A being of type T and B and C
7755 living at offset zero. This occurs frequently in
7756 C++ upcasting and then accessing the base. */
7760 {
7762 tree offset;
7763 machine_mode mode;
7768 /* If the reference was to a (constant) zero offset, we can use
7769 the address of the base if it has the same base type
7770 as the result type and the pointer type is unqualified. */
7777 }
7781 /* Detect assigning a bitfield. */
7783 && DECL_BIT_FIELD
7785 {
7786 /* Don't leave an assignment inside a conversion
7787 unless assigning a bitfield. */
7789 /* First do the assignment, then return converted constant. */
7794 }
7796 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7797 constants (if x has signed type, the sign bit cannot be set
7798 in c). This folds extension into the BIT_AND_EXPR.
7799 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7800 very likely don't have maximal range for their precision and this
7801 transformation effectively doesn't preserve non-maximal ranges. */
7805 {
7816 <= HOST_BITS_PER_WIDE_INT
7818 {
7822 cst &= HOST_WIDE_INT_M1U
7825 #ifdef LOAD_EXTEND_OP
7827 && !flag_syntax_only
7830 {
7834 }
7835 #endif
7836 }
7838 {
7843 }
7844 }
7846 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7847 when one of the new casts will fold away. Conservatively we assume
7848 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7855 {
7859 return fold_build_pointer_plus_loc
7861 }
7863 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7864 of the same precision, and X is an integer type not narrower than
7865 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7871 {
7877 }
7879 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7880 type of X and Y (integer types only). */
7885 {
7886 /* Be careful not to introduce new overflows. */
7887 tree mult_type;
7890 else
7894 {
7901 }
7902 }
7920 /* Convert fabs((double)float) into (double)fabsf(float). */
7923 {
7929 targ0));
7930 }
7932 /* Strip sign ops from argument. */
7934 {
7939 }
7946 {
7952 }
7958 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7977 /* Note that the operand of this must be an int
7978 and its values must be 0 or 1.
7979 ("true" is a fixed value perhaps depending on the language,
7980 but we don't handle values other than 1 correctly yet.) */
7990 {
7998 }
8000 {
8005 }
8007 {
8011 {
8020 }
8021 }
8028 {
8036 }
8038 {
8042 }
8044 {
8048 {
8057 }
8058 }
8062 /* Fold *&X to X if X is an lvalue. */
8064 {
8071 }
8077 }
8080 /* If the operation was a conversion do _not_ mark a resulting constant
8081 with TREE_OVERFLOW if the original constant was not. These conversions
8082 have implementation defined behavior and retaining the TREE_OVERFLOW
8083 flag here would confuse later passes such as VRP. */
8084 tree
8087 {
8096 }
8098 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8099 operands OP0 and OP1. LOC is the location of the resulting expression.
8100 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8101 Return the folded expression if folding is successful. Otherwise,
8102 return NULL_TREE. */
8103 static tree
8106 {
8107 tree tem;
8109 /* We only do these simplifications if we are optimizing. */
8113 /* Check for things like (A || B) && (A || C). We can convert this
8114 to A || (B && C). Note that either operator can be any of the four
8115 truth and/or operations and the transformation will still be
8116 valid. Also note that we only care about order for the
8117 ANDIF and ORIF operators. If B contains side effects, this
8118 might change the truth-value of A. */
8125 {
8145 /* This case if tricky because we must either have commutative
8146 operators or else A10 must not have side-effects. */
8152 a01);
8153 }
8155 /* See if we can build a range comparison. */
8161 {
8165 }
8169 {
8173 }
8175 /* Check for the possibility of merging component references. If our
8176 lhs is another similar operation, try to merge its rhs with our
8177 rhs. Then try to merge our lhs and rhs. */
8191 {
8198 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8199 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8200 We don't want to pack more than two leafs to a non-IF AND/OR
8201 expression.
8202 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8203 equal to IF-CODE, then we don't want to add right-hand operand.
8204 If the inner right-hand side of left-hand operand has
8205 side-effects, or isn't simple, then we can't add to it,
8206 as otherwise we might destroy if-sequence. */
8209 /* Needed for sequence points to handle trappings, and
8210 side-effects. */
8212 {
8214 arg1);
8216 tem);
8217 }
8218 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8219 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8222 /* Needed for sequence points to handle trappings, and
8223 side-effects. */
8225 {
8230 }
8231 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8232 into (A OR B).
8233 For sequence point consistancy, we need to check for trapping,
8234 and side-effects. */
8238 }
8241 }
8243 /* Fold a binary expression of code CODE and type TYPE with operands
8244 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8245 Return the folded expression if folding is successful. Otherwise,
8246 return NULL_TREE. */
8248 static tree
8250 {
8257 else
8260 /* MIN (MAX (a, b), b) == b. */
8265 /* MIN (MAX (b, a), b) == b. */
8271 /* MIN (a, MAX (a, b)) == a. */
8277 /* MIN (a, MAX (b, a)) == a. */
8284 }
8286 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8287 by changing CODE to reduce the magnitude of constants involved in
8288 ARG0 of the comparison.
8289 Returns a canonicalized comparison tree if a simplification was
8290 possible, otherwise returns NULL_TREE.
8291 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8292 valid if signed overflow is undefined. */
8294 static tree
8298 {
8304 /* Match A +- CST code arg1 and CST code arg1. We can change the
8305 first form only if overflow is undefined. */
8308 /* In principle pointers also have undefined overflow behavior,
8309 but that causes problems elsewhere. */
8317 /* Identify the constant in arg0 and its sign. */
8320 else
8324 /* Overflowed constants and zero will cause problems. */
8329 /* See if we can reduce the magnitude of the constant in
8330 arg0 by changing the comparison code. */
8332 {
8333 /* CST <= arg1 -> CST-1 < arg1. */
8336 /* -CST < arg1 -> -CST-1 <= arg1. */
8339 /* CST > arg1 -> CST-1 >= arg1. */
8342 /* -CST >= arg1 -> -CST-1 > arg1. */
8345 else
8347 /* arg1 code' CST' might be more canonical. */
8349 }
8350 else
8351 {
8352 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8356 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8360 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8364 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8368 else
8371 }
8373 /* Now build the constant reduced in magnitude. But not if that
8374 would produce one outside of its types range. */
8382 /* We cannot swap the comparison here as that would cause us to
8383 endlessly recurse. */
8392 /* If swapping might yield to a more canonical form, do so. */
8395 else
8397 }
8399 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8400 overflow further. Try to decrease the magnitude of constants involved
8401 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8402 and put sole constants at the second argument position.
8403 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8405 static tree
8408 {
8409 tree t;
8414 /* Try canonicalization by simplifying arg0. */
8419 {
8423 }
8425 /* Try canonicalization by simplifying arg1 using the swapped
8426 comparison. */
8434 }
8436 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8437 space. This is used to avoid issuing overflow warnings for
8438 expressions like &p->x which can not wrap. */
8440 static bool
8442 {
8449 wide_int wi_offset;
8455 else
8471 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8472 array. */
8474 {
8475 HOST_WIDE_INT base_size;
8480 }
8483 }
8485 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8486 kind INTEGER_CST. This makes sure to properly sign-extend the
8487 constant. */
8489 static HOST_WIDE_INT
8491 {
8497 }
8499 /* Subroutine of fold_binary. This routine performs all of the
8500 transformations that are common to the equality/inequality
8501 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8502 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8503 fold_binary should call fold_binary. Fold a comparison with
8504 tree code CODE and type TYPE with operands OP0 and OP1. Return
8505 the folded comparison or NULL_TREE. */
8507 static tree
8510 {
8520 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8522 && (equality_code
8529 {
8530 const enum tree_code
8537 /* If the constant operation overflowed this can be
8538 simplified as a comparison against INT_MAX/INT_MIN. */
8541 {
8545 /* Get the sign of the constant on the lhs if the
8546 operation were VARIABLE + CONST1. */
8550 /* The sign of the constant determines if we overflowed
8551 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8552 Canonicalize to the INT_MIN overflow by swapping the comparison
8553 if necessary. */
8557 /* We now can look at the canonicalized case
8558 VARIABLE + 1 CODE2 INT_MIN
8559 and decide on the result. */
8561 {
8565 return
8571 return
8576 }
8577 }
8578 else
8579 {
8582 "when changing X +- C1 cmp C2 to "
8584 WARN_STRICT_OVERFLOW_COMPARISON);
8586 }
8587 }
8589 /* For comparisons of pointers we can decompose it to a compile time
8590 comparison of the base objects and the offsets into the object.
8591 This requires at least one operand being an ADDR_EXPR or a
8592 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8598 {
8601 machine_mode mode;
8605 /* Get base and offset for the access. Strip ADDR_EXPR for
8606 get_inner_reference, but put it back by stripping INDIRECT_REF
8607 off the base object if possible. indirect_baseN will be true
8608 if baseN is not an address but refers to the object itself. */
8611 {
8617 else
8619 }
8621 {
8625 {
8628 }
8631 {
8636 {
8639 }
8640 }
8641 }
8645 {
8651 else
8653 }
8655 {
8659 {
8662 }
8665 {
8670 {
8673 }
8674 }
8675 }
8677 /* A local variable can never be pointed to by
8678 the default SSA name of an incoming parameter. */
8680 && indirect_base0
8683 && !indirect_base1
8688 && indirect_base1
8691 && !indirect_base0
8695 {
8700 }
8701 /* If we have equivalent bases we might be able to simplify. */
8704 {
8705 /* We can fold this expression to a constant if the non-constant
8706 offset parts are equal. */
8715 {
8721 "occur when comparing P +- C1 with "
8723 WARN_STRICT_OVERFLOW_CONDITIONAL);
8726 {
8740 }
8741 }
8742 /* We can simplify the comparison to a comparison of the variable
8743 offset parts if the constant offset parts are equal.
8744 Be careful to use signed sizetype here because otherwise we
8745 mess with array offsets in the wrong way. This is possible
8746 because pointer arithmetic is restricted to retain within an
8747 object and overflow on pointer differences is undefined as of
8748 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8750 && (equality_code
8753 {
8754 /* By converting to signed sizetype we cover middle-end pointer
8755 arithmetic which operates on unsigned pointer types of size
8756 type size and ARRAY_REF offsets which are properly sign or
8757 zero extended from their type in case it is narrower than
8758 sizetype. */
8761 else
8765 else
8772 "occur when comparing P +- C1 with "
8774 WARN_STRICT_OVERFLOW_COMPARISON);
8777 }
8778 }
8779 /* For non-equal bases we can simplify if they are addresses
8780 declarations with different addresses. */
8782 /* We know that !operand_equal_p (base0, base1, 0)
8783 because the if condition was false. But make
8784 sure two decls are not the same. */
8790 /* Watch for aliases. */
8795 {
8802 }
8803 /* For equal offsets we can simplify to a comparison of the
8804 base addresses. */
8806 && (indirect_base0
8808 && (indirect_base1
8813 {
8819 }
8820 }
8822 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8823 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8824 the resulting offset is smaller in absolute value than the
8825 original one and has the same sign. */
8834 {
8839 tree cst;
8841 "occur when combining constants around "
8844 /* Put the constant on the side where it doesn't overflow and is
8845 of lower absolute value and of same sign than before. */
8852 {
8855 variable1,
8859 }
8867 {
8873 variable2);
8874 }
8875 }
8883 {
8884 /* If we are widening one operand of an integer comparison,
8885 see if the other operand is similarly being widened. Perhaps we
8886 can do the comparison in the narrower type. */
8891 /* Or if we are changing signedness. */
8895 }
8897 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8898 constant, we can simplify it. */
8903 {
8907 }
8909 /* If we are comparing an expression that just has comparisons
8910 of two integer values, arithmetic expressions of those comparisons,
8911 and constants, we can simplify it. There are only three cases
8912 to check: the two values can either be equal, the first can be
8913 greater, or the second can be greater. Fold the expression for
8914 those three values. Since each value must be 0 or 1, we have
8915 eight possibilities, each of which corresponds to the constant 0
8916 or 1 or one of the six possible comparisons.
8918 This handles common cases like (a > b) == 0 but also handles
8919 expressions like ((x > y) - (y > x)) > 0, which supposedly
8920 occur in macroized code. */
8923 {
8928 /* Don't handle degenerate cases here; they should already
8929 have been handled anyway. */
8938 {
8942 /* We can't just pass T to eval_subst in case cval1 or cval2
8943 was the same as ARG1. */
8945 tree high_result
8949 arg1);
8950 tree equal_result
8954 arg1);
8955 tree low_result
8959 arg1);
8961 /* All three of these results should be 0 or 1. Confirm they are.
8962 Then use those values to select the proper code to use. */
8967 {
8968 /* Make a 3-bit mask with the high-order bit being the
8969 value for `>', the next for '=', and the low for '<'. */
8973 {
8975 /* Always false. */
8996 /* Always true. */
8998 }
9001 {
9005 }
9007 }
9008 }
9009 }
9011 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9012 into a single range test. */
9020 {
9024 }
9027 }
9030 /* Subroutine of fold_binary. Optimize complex multiplications of the
9031 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9032 argument EXPR represents the expression "z" of type TYPE. */
9034 static tree
9036 {
9041 {
9044 }
9046 {
9049 }
9050 else
9051 {
9055 }
9064 }
9067 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9068 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9070 static bool
9072 {
9076 {
9079 }
9081 {
9087 else
9089 }
9090 else
9096 }
9098 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9099 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9100 NULL_TREE otherwise. */
9102 static tree
9104 {
9121 {
9125 }
9128 {
9134 }
9135 else
9137 }
9139 /* Try to fold a pointer difference of type TYPE two address expressions of
9140 array references AREF0 and AREF1 using location LOC. Return a
9141 simplified expression for the difference or NULL_TREE. */
9143 static tree
9146 {
9151 /* If the bases are array references as well, recurse. If the bases
9152 are pointer indirections compute the difference of the pointers.
9153 If the bases are equal, we are set. */
9156 && (base_offset
9164 {
9170 base_offset,
9173 }
9175 }
9177 /* If the real or vector real constant CST of type TYPE has an exact
9178 inverse, return it, else return NULL. */
9180 tree
9182 {
9183 REAL_VALUE_TYPE r;
9185 machine_mode mode;
9189 {
9205 {
9210 }
9216 }
9217 }
9219 /* Mask out the tz least significant bits of X of type TYPE where
9220 tz is the number of trailing zeroes in Y. */
9221 static wide_int
9223 {
9228 }
9230 /* Return true when T is an address and is known to be nonzero.
9231 For floating point we further ensure that T is not denormal.
9232 Similar logic is present in nonzero_address in rtlanal.h.
9234 If the return value is based on the assumption that signed overflow
9235 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9236 change *STRICT_OVERFLOW_P. */
9238 static bool
9240 {
9244 /* Doing something useful for floating point would need more work. */
9250 {
9253 strict_overflow_p);
9259 strict_overflow_p);
9267 }
9270 {
9273 strict_overflow_p);
9281 strict_overflow_p);
9296 strict_overflow_p);
9300 strict_overflow_p);
9303 {
9315 }
9319 }
9321 }
9323 /* Return true when T is an address and is known to be nonzero.
9324 Handle warnings about undefined signed overflow. */
9326 static bool
9328 {
9335 "determining that expression is always "
9337 WARN_STRICT_OVERFLOW_MISC);
9339 }
9341 /* Fold a binary expression of code CODE and type TYPE with operands
9342 OP0 and OP1. LOC is the location of the resulting expression.
9343 Return the folded expression if folding is successful. Otherwise,
9344 return NULL_TREE. */
9346 tree
9349 {
9364 /* Strip any conversions that don't change the mode. This is
9365 safe for every expression, except for a comparison expression
9366 because its signedness is derived from its operands. So, in
9367 the latter case, only strip conversions that don't change the
9368 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9369 preserved.
9371 Note that this is done as an internal manipulation within the
9372 constant folder, in order to find the simplest representation
9373 of the arguments so that their form can be studied. In any
9374 cases, the appropriate type conversions should be put back in
9375 the tree that will get out of the constant folder. */
9378 {
9381 }
9382 else
9383 {
9386 }
9388 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9389 constant but we can't do arithmetic on them. */
9391 {
9394 {
9398 }
9399 }
9401 /* If this is a commutative operation, and ARG0 is a constant, move it
9402 to ARG1 to reduce the number of tests below. */
9407 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9408 to ARG1 to reduce the number of tests below. */
9417 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9419 First check for cases where an arithmetic operation is applied to a
9420 compound, conditional, or comparison operation. Push the arithmetic
9421 operation inside the compound or conditional to see if any folding
9422 can then be done. Convert comparison to conditional for this purpose.
9423 The also optimizes non-constant cases that used to be done in
9424 expand_expr.
9426 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9427 one of the operands is a comparison and the other is a comparison, a
9428 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9429 code below would make the expression more complex. Change it to a
9430 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9431 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9444 {
9448 boolean_type_node,
9456 }
9460 {
9462 {
9467 tem);
9468 }
9471 {
9476 tem);
9477 }
9482 {
9488 }
9493 {
9499 }
9500 }
9503 {
9505 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9508 {
9514 }
9516 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9519 {
9520 tree base;
9521 HOST_WIDE_INT coffset;
9530 }
9535 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9541 arg1),
9543 arg0)));
9549 {
9550 /* X + (X / CST) * -CST is X % CST. */
9555 {
9564 cst0));
9565 }
9566 }
9568 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9569 one. Make sure the type is not saturating and has the signedness of
9570 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9571 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9578 {
9582 }
9585 {
9586 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9587 with a constant, and the two constants have no bits in common,
9588 we should treat this as a BIT_IOR_EXPR since this may produce more
9589 simplifications. */
9596 {
9599 }
9601 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9602 (plus (plus (mult) (mult)) (foo)) so that we can
9603 take advantage of the factoring cases below. */
9612 {
9618 else
9631 parg0),
9633 marg)),
9637 return
9643 parg1)));
9644 }
9645 }
9646 else
9647 {
9648 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9649 to __complex__ ( x, y ). This is not the same for SNaNs or
9650 if signed zeros are involved. */
9654 {
9661 {
9665 {
9671 }
9673 {
9679 }
9680 }
9681 }
9689 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9690 We associate floats only if the user has specified
9691 -fassociative-math. */
9695 {
9700 {
9701 tree tree0;
9704 }
9705 }
9706 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9707 We associate floats only if the user has specified
9708 -fassociative-math. */
9712 {
9717 {
9718 tree tree0;
9721 }
9722 }
9723 }
9725 bit_rotate:
9726 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9727 is a rotate of A by C1 bits. */
9728 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9729 is a rotate of A by B bits. */
9730 {
9732 tree rtype;
9741 /* Only create rotates in complete modes. Other cases are not
9742 expanded properly. */
9745 {
9759 {
9763 code0 == LSHIFT_EXPR
9767 }
9769 {
9777 element_precision
9781 return
9784 ? LROTATE_EXPR
9789 }
9791 {
9799 element_precision
9803 return fold_convert_loc
9806 ? LROTATE_EXPR
9810 }
9811 }
9812 }
9814 associate:
9815 /* In most languages, can't associate operations on floats through
9816 parentheses. Rather than remember where the parentheses were, we
9817 don't associate floats at all, unless the user has specified
9818 -fassociative-math.
9819 And, we need to make sure type is not saturating. */
9823 {
9829 /* Split both trees into variables, constants, and literals. Then
9830 associate each group together, the constants with literals,
9831 then the result with variables. This increases the chances of
9832 literals being recombined later and of generating relocatable
9833 expressions for the sum of a constant and literal. */
9838 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9842 /* With undefined overflow prefer doing association in a type
9843 which wraps on overflow, if that is one of the operand types. */
9846 {
9854 }
9856 /* With undefined overflow we can only associate constants with one
9857 variable, and constants whose association doesn't overflow. */
9860 {
9862 {
9880 /* The only case we can still associate with two variables
9881 is if they are the same, modulo negation and bit-pattern
9882 preserving conversions. */
9885 }
9886 }
9888 /* Only do something if we found more than two objects. Otherwise,
9889 nothing has changed and we risk infinite recursion. */
9895 {
9907 /* Preserve the MINUS_EXPR if the negative part of the literal is
9908 greater than the positive part. Otherwise, the multiplicative
9909 folding code (i.e extract_muldiv) may be fooled in case
9910 unsigned constants are subtracted, like in the following
9911 example: ((X*2 + 4) - 8U)/2. */
9913 {
9917 {
9921 }
9922 else
9923 {
9927 }
9928 }
9930 /* Don't introduce overflows through reassociation. */
9937 {
9939 return
9943 else
9944 {
9947 return
9951 }
9952 }
9955 return
9958 }
9959 }
9964 /* Pointer simplifications for subtraction, simple reassociations. */
9966 {
9967 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
9970 {
9980 }
9981 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
9983 {
9990 }
9991 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
9992 simplifies. */
9994 {
10001 arg10);
10004 }
10005 }
10006 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10017 {
10018 /* Fold A - (A & B) into ~B & A. */
10021 {
10023 {
10030 }
10032 {
10039 }
10040 }
10042 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10043 any power of 2 minus 1. */
10048 {
10054 {
10058 }
10059 }
10060 }
10062 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10063 __complex__ ( x, -y ). This is not the same for SNaNs or if
10064 signed zeros are involved. */
10068 {
10075 {
10079 {
10081 arg1r ? arg1r
10086 }
10088 {
10092 arg1i ? arg1i
10095 }
10096 }
10097 }
10099 /* A - B -> A + (-B) if B is easily negatable. */
10103 /* Avoid this transformation if B is a positive REAL_CST. */
10112 /* Fold &a[i] - &a[j] to i-j. */
10117 {
10123 }
10126 && flag_unsafe_math_optimizations
10132 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10133 one. Make sure the type is not saturating and has the signedness of
10134 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10135 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10142 {
10146 }
10151 /* (-A) * (-B) -> A * B */
10166 {
10167 /* Transform x * -C into -x * C if x is easily negatable. */
10176 tem);
10178 /* (a * (1 << b)) is (a << b) */
10188 /* (A + A) * C -> A * 2 * C */
10200 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10201 sign-changing only. */
10211 {
10214 "occur when simplifying "
10216 WARN_STRICT_OVERFLOW_MISC);
10218 }
10220 /* Optimize z * conj(z) for integer complex numbers. */
10227 }
10228 else
10229 {
10230 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10231 the result for floating point types due to rounding so it is applied
10232 only if -fassociative-math was specify. */
10237 {
10239 arg1);
10243 }
10245 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10247 {
10250 {
10253 }
10254 }
10256 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10257 This is not the same for NaNs or if signed zeros are
10258 involved. */
10264 {
10267 return
10273 return
10278 }
10280 /* Optimize z * conj(z) for floating point complex numbers.
10281 Guarded by flag_unsafe_math_optimizations as non-finite
10282 imaginary components don't produce scalar results. */
10293 {
10297 /* Optimizations of root(...)*root(...). */
10299 {
10304 /* Optimize sqrt(x)*sqrt(x) as x. */
10310 /* Optimize root(x)*root(y) as root(x*y). */
10314 }
10316 /* Optimize expN(x)*expN(y) as expN(x+y). */
10318 {
10324 }
10326 /* Optimizations of pow(...)*pow(...). */
10330 {
10336 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10338 {
10343 }
10345 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10347 {
10352 }
10353 }
10355 /* Optimize tan(x)*cos(x) as sin(x). */
10364 {
10370 }
10372 /* Optimize x*pow(x,c) as pow(x,c+1). */
10376 {
10382 {
10384 REAL_VALUE_TYPE c;
10385 tree arg;
10391 }
10392 }
10394 /* Optimize pow(x,c)*x as pow(x,c+1). */
10398 {
10404 {
10406 REAL_VALUE_TYPE c;
10407 tree arg;
10413 }
10414 }
10416 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10418 && optimize
10420 {
10424 {
10427 }
10428 }
10429 }
10430 }
10434 bit_ior:
10435 /* Canonicalize (X & C1) | C2. */
10439 {
10444 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10452 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10457 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10458 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10459 mode which allows further optimizations. */
10464 {
10468 {
10471 }
10472 }
10479 c3)),
10480 arg1);
10481 }
10483 /* (X & ~Y) | (~X & Y) is X ^ Y */
10486 {
10503 }
10509 /* See if this can be simplified into a rotate first. If that
10510 is unsuccessful continue in the association code. */
10514 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10522 /* See if this can be simplified into a rotate first. If that
10523 is unsuccessful continue in the association code. */
10527 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
10535 /* X & ~X , X & (X == 0), and X & !X are always zero. */
10543 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10548 {
10549 tree tem2;
10556 }
10557 /* Fold ~X & 1 as (X & 1) == 0. */
10561 {
10562 tree tem2;
10569 }
10570 /* Fold !X & 1 as X == 0. */
10573 {
10577 }
10579 /* Fold (X ^ Y) & Y as ~X & Y. */
10582 {
10587 }
10588 /* Fold (X ^ Y) & X as ~Y & X. */
10592 {
10597 }
10598 /* Fold X & (X ^ Y) as X & ~Y. */
10601 {
10606 }
10607 /* Fold X & (Y ^ X) as ~Y & X. */
10611 {
10616 }
10618 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10619 multiple of 1 << CST. */
10621 {
10628 }
10630 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10631 bits from CST2. */
10635 {
10643 {
10644 /* Avoid the transform if arg1 is a mask of some
10645 mode which allows further optimizations. */
10652 }
10653 }
10655 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10656 ((A & N) + B) & M -> (A + B) & M
10657 Similarly if (N & M) == 0,
10658 ((A | N) + B) & M -> (A + B) & M
10659 and for - instead of + (or unary - instead of +)
10660 and/or ^ instead of |.
10661 If B is constant and (B & M) == 0, fold into A & M. */
10663 {
10672 {
10675 wide_int cst0;
10677 /* Now we know that arg0 is (C + D) or (C - D) or
10678 -C and arg1 (M) is == (1LL << cst) - 1.
10679 Store C into PMOP[0] and D into PMOP[1]. */
10683 {
10686 }
10693 {
10703 {
10706 }
10709 /* If C or D is of the form (A & N) where
10710 (N & M) == M, or of the form (A | N) or
10711 (A ^ N) where (N & M) == 0, replace it with A. */
10715 /* If C or D is a N where (N & M) == 0, it can be
10716 omitted (assumed 0). */
10724 }
10726 /* Only build anything new if we optimized one or both arguments
10727 above. */
10731 {
10734 {
10735 /* Perform the operations in a type that has defined
10736 overflow behavior. */
10742 }
10747 {
10755 else
10757 }
10760 else
10763 /* TEM is now the new binary +, - or unary - replacement. */
10767 }
10768 }
10769 }
10774 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10777 {
10782 return
10784 }
10789 /* Don't touch a floating-point divide by zero unless the mode
10790 of the constant can represent infinity. */
10796 /* (-A) / (-B) -> A / B */
10806 /* Convert A/B/C to A/(B*C). */
10813 /* Convert A/(B/C) to (A/B)*C. */
10821 /* Convert C1/(X*C2) into (C1/C2)/X. */
10826 {
10832 }
10835 {
10839 /* Optimize sin(x)/cos(x) as tan(x). */
10845 {
10850 }
10852 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10858 {
10862 {
10867 }
10868 }
10870 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10871 NaNs or Infinities. */
10875 {
10882 {
10887 }
10888 }
10890 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10891 NaNs or Infinities. */
10895 {
10902 {
10906 {
10910 tmp);
10911 }
10912 }
10913 }
10915 /* Optimize pow(x,c)/x as pow(x,c-1). */
10919 {
10925 {
10927 REAL_VALUE_TYPE c;
10928 tree arg;
10934 }
10935 }
10937 /* Optimize a/root(b/c) into a*root(c/b). */
10939 {
10943 {
10952 }
10953 }
10955 /* Optimize x/expN(y) into x*expN(-y). */
10957 {
10964 }
10966 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10970 {
10978 }
10979 }
10983 /* Optimize (X & (-A)) / A where A is a power of 2,
10984 to X >> log2(A) */
10988 {
10996 }
10997 }
10999 /* Fall through */
11002 /* Simplify A / (B << N) where A and B are positive and B is
11003 a power of 2, to A >> (N + log2(B)). */
11008 {
11011 {
11019 WARN_STRICT_OVERFLOW_MISC);
11025 }
11026 }
11028 /* Fall through */
11036 /* Convert -A / -B to A / B when the type is signed and overflow is
11037 undefined. */
11041 {
11044 "when distributing negation across "
11046 WARN_STRICT_OVERFLOW_MISC);
11052 }
11056 {
11059 "when distributing negation across "
11061 WARN_STRICT_OVERFLOW_MISC);
11067 }
11069 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11070 operation, EXACT_DIV_EXPR.
11072 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11073 At one time others generated faster code, it's not clear if they do
11074 after the last round to changes to the DIV code in expmed.c. */
11083 {
11087 WARN_STRICT_OVERFLOW_MISC);
11089 }
11101 {
11105 WARN_STRICT_OVERFLOW_MISC);
11107 }
11115 /* Since negative shift count is not well-defined,
11116 don't try to compute it in the compiler. */
11122 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11127 {
11131 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11132 being well defined. */
11134 {
11140 else
11142 }
11146 }
11148 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11149 into x & ((unsigned)-1 >> c) for unsigned types. */
11157 {
11160 tree lshift;
11161 tree arg00;
11164 {
11171 }
11172 }
11174 /* If we have a rotate of a bit operation with the rotate count and
11175 the second operand of the bit operation both constant,
11176 permute the two operations. */
11188 /* Two consecutive rotates adding up to the some integer
11189 multiple of the precision of the type can be ignored. */
11197 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11198 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11199 if the latter can be further optimized. */
11204 {
11208 arg1);
11212 arg1);
11216 }
11233 /* Note that the operands of this must be ints
11234 and their values must be 0 or 1.
11235 ("true" is a fixed value perhaps depending on the language.) */
11236 /* If first arg is constant zero, return it. */
11240 /* If either arg is constant true, drop it. */
11244 /* Preserve sequence points. */
11247 /* If second arg is constant zero, result is zero, but first arg
11248 must be evaluated. */
11251 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11252 case will be handled here. */
11256 /* !X && X is always false. */
11260 /* X && !X is always false. */
11265 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
11266 means A >= Y && A != MAX, but in this case we know that
11267 A < X <= MAX. */
11271 {
11279 }
11288 /* Note that the operands of this must be ints
11289 and their values must be 0 or true.
11290 ("true" is a fixed value perhaps depending on the language.) */
11291 /* If first arg is constant true, return it. */
11295 /* If either arg is constant zero, drop it. */
11299 /* Preserve sequence points. */
11302 /* If second arg is constant true, result is true, but we must
11303 evaluate first arg. */
11306 /* Likewise for first arg, but note this only occurs here for
11307 TRUTH_OR_EXPR. */
11311 /* !X || X is always true. */
11315 /* X || !X is always true. */
11320 /* (X && !Y) || (!X && Y) is X ^ Y */
11323 {
11340 }
11349 /* If the second arg is constant zero, drop it. */
11352 /* If the second arg is constant true, this is a logical inversion. */
11354 {
11357 }
11358 /* Identical arguments cancel to zero. */
11362 /* !X ^ X is always true. */
11367 /* X ^ !X is always true. */
11383 /* bool_var != 0 becomes bool_var. */
11388 /* bool_var == 1 becomes bool_var. */
11393 /* bool_var != 1 becomes !bool_var. */
11400 /* bool_var == 0 becomes !bool_var. */
11407 /* !exp != 0 becomes !exp */
11412 /* If this is an equality comparison of the address of two non-weak,
11413 unaliased symbols neither of which are extern (since we do not
11414 have access to attributes for externs), then we know the result. */
11419 {
11427 else
11432 type);
11433 }
11435 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11443 arg1),
11446 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
11455 {
11459 val,
11463 }
11465 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
11472 {
11474 code == NE_EXPR
11477 }
11479 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11484 /* If this is an EQ or NE comparison with zero and ARG0 is
11485 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11486 two operations, but the latter can be done in one less insn
11487 on machines that have only two-operand insns or on which a
11488 constant cannot be the first operand. */
11491 {
11496 {
11503 arg1);
11504 }
11507 {
11514 arg1);
11515 }
11516 }
11518 /* If this is an NE or EQ comparison of zero against the result of a
11519 signed MOD operation whose second operand is a power of 2, make
11520 the MOD operation unsigned since it is simpler and equivalent. */
11528 {
11538 }
11540 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11541 C1 is a valid shift constant, and C2 is a power of two, i.e.
11542 a single bit. */
11546 == INTEGER_CST
11549 {
11554 /* Check for a valid shift count. */
11556 {
11560 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11561 can be rewritten as (X & (C2 << C1)) != 0. */
11563 {
11568 }
11569 /* Otherwise, for signed (arithmetic) shifts,
11570 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11571 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11575 /* Otherwise, of unsigned (logical) shifts,
11576 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11577 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11578 else
11582 arg000);
11583 }
11584 }
11586 /* If we have (A & C) == C where C is a power of 2, convert this into
11587 (A & C) != 0. Similarly for NE_EXPR. */
11593 integer_zero_node));
11595 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11596 bit, then fold the expression into A < 0 or A >= 0. */
11601 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11602 Similarly for NE_EXPR. */
11606 {
11610 tree dandnotc
11613 notc);
11617 }
11619 /* If this is a comparison of a field, we may be able to simplify it. */
11622 /* Handle the constant case even without -O
11623 to make sure the warnings are given. */
11625 {
11629 }
11631 /* Optimize comparisons of strlen vs zero to a compare of the
11632 first character of the string vs zero. To wit,
11633 strlen(ptr) == 0 => *ptr == 0
11634 strlen(ptr) != 0 => *ptr != 0
11635 Other cases should reduce to one of these two (or a constant)
11636 due to the return value of strlen being unsigned. */
11639 {
11647 {
11652 }
11653 }
11655 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11656 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11660 {
11665 {
11667 {
11670 }
11673 }
11674 }
11676 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11677 (X & C) == 0 when C is a single bit. */
11682 {
11689 arg1));
11690 }
11692 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11693 constant C is a power of two, i.e. a single bit. */
11700 {
11704 }
11706 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11707 when is C is a power of two, i.e. a single bit. */
11714 {
11720 }
11724 {
11727 }
11729 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11732 {
11745 arg01),
11754 arg01),
11763 arg00),
11772 arg00),
11774 }
11778 {
11785 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11786 operand_equal_p guarantees no side-effects so we don't need
11787 to use omit_one_operand on Z. */
11791 arg10));
11795 arg11));
11799 arg10));
11803 arg11));
11805 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11808 {
11814 }
11815 }
11817 /* Attempt to simplify equality/inequality comparisons of complex
11818 values. Only lower the comparison if the result is known or
11819 can be simplified to a single scalar comparison. */
11824 {
11829 {
11832 }
11833 else
11834 {
11837 }
11840 {
11843 }
11844 else
11845 {
11848 }
11852 {
11854 {
11859 }
11860 else
11861 {
11866 }
11867 }
11871 {
11873 {
11878 }
11879 else
11880 {
11885 }
11886 }
11887 }
11899 /* Transform comparisons of the form X +- C CMP X. */
11906 {
11913 else
11916 /* (X - c) > X becomes false. */
11920 {
11924 "occur when assuming that (X - c) > X "
11926 WARN_STRICT_OVERFLOW_ALL);
11928 }
11930 /* Likewise (X + c) < X becomes false. */
11934 {
11938 "occur when assuming that "
11940 WARN_STRICT_OVERFLOW_ALL);
11942 }
11944 /* Convert (X - c) <= X to true. */
11949 {
11953 "occur when assuming that "
11955 WARN_STRICT_OVERFLOW_ALL);
11957 }
11959 /* Convert (X + c) >= X to true. */
11964 {
11968 "occur when assuming that "
11970 WARN_STRICT_OVERFLOW_ALL);
11972 }
11975 {
11976 /* Convert X + c > X and X - c < X to true for integers. */
11980 {
11983 "not occur when assuming that "
11985 WARN_STRICT_OVERFLOW_ALL);
11987 }
11992 {
11995 "not occur when assuming that "
11997 WARN_STRICT_OVERFLOW_ALL);
11999 }
12001 /* Convert X + c <= X and X - c >= X to false for integers. */
12005 {
12008 "not occur when assuming that "
12010 WARN_STRICT_OVERFLOW_ALL);
12012 }
12017 {
12020 "not occur when assuming that "
12022 WARN_STRICT_OVERFLOW_ALL);
12024 }
12025 }
12026 }
12028 /* Comparisons with the highest or lowest possible integer of
12029 the specified precision will have known values. */
12030 {
12036 {
12043 {
12056 /* The GE_EXPR and LT_EXPR cases above are not normally
12057 reached because of previous transformations. */
12061 }
12064 {
12071 arg1);
12077 arg0),
12078 arg1);
12081 }
12084 {
12099 }
12102 {
12109 arg1);
12115 arg0),
12116 arg1);
12119 }
12123 /* We will flip the signedness of the comparison operator
12124 associated with the mode of arg1, so the sign bit is
12125 specified by this mode. Check that arg1 is the signed
12126 max associated with this sign bit. */
12128 /* signed_type does not work on pointer types. */
12130 {
12131 /* The following case also applies to X < signed_max+1
12132 and X >= signed_max+1 because previous transformations. */
12134 {
12140 }
12141 }
12142 }
12143 }
12145 /* If we are comparing an ABS_EXPR with a constant, we can
12146 convert all the cases into explicit comparisons, but they may
12147 well not be faster than doing the ABS and one comparison.
12148 But ABS (X) <= C is a range comparison, which becomes a subtraction
12149 and a comparison, and is probably faster. */
12163 /* Convert ABS_EXPR<x> >= 0 to true. */
12170 {
12173 "when simplifying comparison of "
12175 WARN_STRICT_OVERFLOW_CONDITIONAL);
12178 arg0);
12179 }
12181 /* Convert ABS_EXPR<x> < 0 to false. */
12186 {
12189 "when simplifying comparison of "
12191 WARN_STRICT_OVERFLOW_CONDITIONAL);
12194 arg0);
12195 }
12197 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12198 and similarly for >= into !=. */
12208 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
12209 otherwise Y might be >= # of bits in X's type and thus e.g.
12210 (unsigned char) (1 << Y) for Y 15 might be 0.
12211 If the cast is widening, then 1 << Y should have unsigned type,
12212 otherwise if Y is number of bits in the signed shift type minus 1,
12213 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
12214 31 might be 0xffffffff80000000. */
12225 {
12231 }
12244 {
12248 }
12250 /* If the first operand is NaN, the result is constant. */
12254 {
12256 ? integer_zero_node
12259 }
12261 /* If the second operand is NaN, the result is constant. */
12265 {
12267 ? integer_zero_node
12270 }
12272 /* Simplify unordered comparison of something with itself. */
12278 && !flag_trapping_math
12282 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12283 {
12295 }
12300 /* When pedantic, a compound expression can be neither an lvalue
12301 nor an integer constant expression. */
12304 /* Don't let (0, 0) be null pointer constant. */
12310 /* An ASSERT_EXPR should never be passed to fold_binary. */
12316 }
12318 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
12319 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
12320 of GOTO_EXPR. */
12322 static tree
12324 {
12326 {
12333 /* ... fall through ... */
12337 }
12338 }
12340 /* Return whether the sub-tree ST contains a label which is accessible from
12341 outside the sub-tree. */
12343 static bool
12345 {
12346 return
12348 }
12350 /* Fold a ternary expression of code CODE and type TYPE with operands
12351 OP0, OP1, and OP2. Return the folded expression if folding is
12352 successful. Otherwise, return NULL_TREE. */
12354 tree
12357 {
12358 tree tem;
12365 /* If this is a commutative operation, and OP0 is a constant, move it
12366 to OP1 to reduce the number of tests below. */
12375 /* Strip any conversions that don't change the mode. This is safe
12376 for every expression, except for a comparison expression because
12377 its signedness is derived from its operands. So, in the latter
12378 case, only strip conversions that don't change the signedness.
12380 Note that this is done as an internal manipulation within the
12381 constant folder, in order to find the simplest representation of
12382 the arguments so that their form can be studied. In any cases,
12383 the appropriate type conversions should be put back in the tree
12384 that will get out of the constant folder. */
12386 {
12389 }
12392 {
12395 }
12398 {
12401 }
12404 {
12408 {
12414 }
12419 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12420 so all simple results must be passed through pedantic_non_lvalue. */
12422 {
12425 /* Only optimize constant conditions when the selected branch
12426 has the same type as the COND_EXPR. This avoids optimizing
12427 away "c ? x : throw", where the throw has a void type.
12428 Avoid throwing away that operand which contains label. */
12435 }
12437 {
12442 {
12447 {
12455 }
12459 }
12460 }
12462 /* If we have A op B ? A : C, we may be able to convert this to a
12463 simpler expression, depending on the operation and the values
12464 of B and C. Signed zeros prevent all of these transformations,
12465 for reasons given above each one.
12467 Also try swapping the arguments and inverting the conditional. */
12472 {
12476 }
12480 op2,
12483 {
12487 {
12491 }
12492 }
12494 /* If the second operand is simpler than the third, swap them
12495 since that produces better jump optimization results. */
12498 {
12500 /* See if this can be inverted. If it can't, possibly because
12501 it was a floating-point inequality comparison, don't do
12502 anything. */
12506 }
12508 /* Convert A ? 1 : 0 to simply A. */
12513 /* If we try to convert OP0 to our type, the
12514 call to fold will try to move the conversion inside
12515 a COND, which will recurse. In that case, the COND_EXPR
12516 is probably the best choice, so leave it alone. */
12520 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12521 over COND_EXPR in cases such as floating point comparisons. */
12530 arg0)));
12532 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12537 {
12538 /* sign_bit_p looks through both zero and sign extensions,
12539 but for this optimization only sign extensions are
12540 usable. */
12543 {
12546 {
12549 }
12551 }
12552 /* sign_bit_p only checks ARG1 bits within A's precision.
12553 If <sign bit of A> has wider type than A, bits outside
12554 of A's precision in <sign bit of A> need to be checked.
12555 If they are all 0, this optimization needs to be done
12556 in unsigned A's type, if they are all 1 in signed A's type,
12557 otherwise this can't be done. */
12563 {
12565 tree tem_type;
12578 {
12581 }
12583 {
12586 }
12587 else
12589 }
12592 return
12598 arg1)));
12599 }
12601 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12602 already handled above. */
12607 {
12616 }
12618 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12619 is probably obsolete because the first operand should be a
12620 truth value (that's why we have the two cases above), but let's
12621 leave it in until we can confirm this for all front-ends. */
12633 /* Disable the transformations below for vectors, since
12634 fold_binary_op_with_conditional_arg may undo them immediately,
12635 yielding an infinite loop. */
12639 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12648 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12653 {
12655 /* Only perform transformation if ARG0 is easily inverted. */
12659 ? BIT_IOR_EXPR
12662 arg1);
12663 }
12665 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
12670 {
12672 /* Only perform transformation if ARG0 is easily inverted. */
12678 op2);
12679 }
12681 /* Convert A ? 1 : B into A || B if A and B are truth values. */
12693 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
12694 of fold_ternary on them. */
12704 {
12714 {
12719 {
12727 }
12729 /* Constructor elements can be subvectors. */
12732 {
12736 }
12738 /* We keep an exact subset of the constructor elements. */
12740 {
12746 {
12750 }
12758 CONSTRUCTOR_ELT
12761 }
12762 /* The bitfield references a single constructor element. */
12764 {
12769 else
12773 }
12774 }
12775 }
12777 /* A bit-field-ref that referenced the full argument can be stripped. */
12783 /* On constants we can use native encode/interpret to constant
12784 fold (nearly) all BIT_FIELD_REFs. */
12788 /* This limitation should not be necessary, we just need to
12789 round this up to mode size. */
12791 /* Need bit-shifting of the buffer to relax the following. */
12793 {
12798 /* ??? We cannot tell native_encode_expr to start at
12799 some random byte only. So limit us to a reasonable amount
12800 of work. */
12802 {
12807 {
12813 }
12814 }
12815 }
12820 /* For integers we can decompose the FMA if possible. */
12832 {
12848 {
12853 /* Make sure that the perm value is in an acceptable
12854 range. */
12863 else
12868 }
12871 {
12876 }
12881 {
12886 }
12892 {
12896 }
12901 /* Some targets are deficient and fail to expand a single
12902 argument permutation while still allowing an equivalent
12903 2-argument version. */
12907 {
12910 }
12913 {
12920 }
12924 }
12930 }
12932 /* Perform constant folding and related simplification of EXPR.
12933 The related simplifications include x*1 => x, x*0 => 0, etc.,
12934 and application of the associative law.
12935 NOP_EXPR conversions may be removed freely (as long as we
12936 are careful not to change the type of the overall expression).
12937 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12938 but we can constant-fold them if they have constant operands. */
12940 #ifdef ENABLE_FOLD_CHECKING
12941 # define fold(x) fold_1 (x)
12943 static
12944 #endif
12945 tree
12947 {
12951 tree tem;
12954 /* Return right away if a constant. */
12958 /* CALL_EXPR-like objects with variable numbers of operands are
12959 treated specially. */
12961 {
12963 {
12966 }
12968 }
12971 {
12976 {
12994 }
12995 }
12998 {
13000 {
13007 {
13012 /* Find a matching index by means of a binary search. */
13014 {
13030 else
13032 }
13033 }
13036 }
13038 /* Return a VECTOR_CST if possible. */
13040 {
13047 tree value;
13050 {
13054 {
13057 }
13058 else
13060 }
13065 }
13073 }
13075 #ifdef ENABLE_FOLD_CHECKING
13076 #undef fold
13083 /* When --enable-checking=fold, compute a digest of expr before
13084 and after actual fold call to see if fold did not accidentally
13085 change original expr. */
13087 tree
13089 {
13090 tree ret;
13110 }
13112 void
13114 {
13125 }
13127 static void
13129 {
13131 }
13133 static void
13136 {
13142 recursive_label:
13152 {
13153 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
13158 }
13165 {
13166 /* Allow these fields to be modified. */
13167 tree tmp;
13175 {
13178 }
13179 }
13190 {
13193 {
13208 }
13212 {
13225 }
13242 {
13248 }
13251 {
13253 {
13256 }
13258 }
13269 {
13272 }
13282 }
13283 }
13285 /* Helper function for outputting the checksum of a tree T. When
13286 debugging with gdb, you can "define mynext" to be "next" followed
13287 by "call debug_fold_checksum (op0)", then just trace down till the
13288 outputs differ. */
13290 DEBUG_FUNCTION void
13292 {
13307 }
13309 #endif
13311 /* Fold a unary tree expression with code CODE of type TYPE with an
13312 operand OP0. LOC is the location of the resulting expression.
13313 Return a folded expression if successful. Otherwise, return a tree
13314 expression with code CODE of type TYPE with an operand OP0. */
13316 tree
13319 {
13320 tree tem;
13321 #ifdef ENABLE_FOLD_CHECKING
13330 #endif
13336 #ifdef ENABLE_FOLD_CHECKING
13343 #endif
13345 }
13347 /* Fold a binary tree expression with code CODE of type TYPE with
13348 operands OP0 and OP1. LOC is the location of the resulting
13349 expression. Return a folded expression if successful. Otherwise,
13350 return a tree expression with code CODE of type TYPE with operands
13351 OP0 and OP1. */
13353 tree
13356 MEM_STAT_DECL)
13357 {
13358 tree tem;
13359 #ifdef ENABLE_FOLD_CHECKING
13376 #endif
13382 #ifdef ENABLE_FOLD_CHECKING
13397 #endif
13399 }
13401 /* Fold a ternary tree expression with code CODE of type TYPE with
13402 operands OP0, OP1, and OP2. Return a folded expression if
13403 successful. Otherwise, return a tree expression with code CODE of
13404 type TYPE with operands OP0, OP1, and OP2. */
13406 tree
13409 {
13410 tree tem;
13411 #ifdef ENABLE_FOLD_CHECKING
13435 #endif
13442 #ifdef ENABLE_FOLD_CHECKING
13465 #endif
13467 }
13469 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
13470 arguments in ARGARRAY, and a null static chain.
13471 Return a folded expression if successful. Otherwise, return a CALL_EXPR
13472 of type TYPE from the given operands as constructed by build_call_array. */
13474 tree
13477 {
13478 tree tem;
13479 #ifdef ENABLE_FOLD_CHECKING
13498 #endif
13504 #ifdef ENABLE_FOLD_CHECKING
13520 #endif
13522 }
13524 /* Perform constant folding and related simplification of initializer
13525 expression EXPR. These behave identically to "fold_buildN" but ignore
13526 potential run-time traps and exceptions that fold must preserve. */
13528 #define START_FOLD_INIT \
13529 int saved_signaling_nans = flag_signaling_nans;\
13530 int saved_trapping_math = flag_trapping_math;\
13531 int saved_rounding_math = flag_rounding_math;\
13532 int saved_trapv = flag_trapv;\
13533 int saved_folding_initializer = folding_initializer;\
13534 flag_signaling_nans = 0;\
13535 flag_trapping_math = 0;\
13536 flag_rounding_math = 0;\
13537 flag_trapv = 0;\
13538 folding_initializer = 1;
13540 #define END_FOLD_INIT \
13541 flag_signaling_nans = saved_signaling_nans;\
13542 flag_trapping_math = saved_trapping_math;\
13543 flag_rounding_math = saved_rounding_math;\
13544 flag_trapv = saved_trapv;\
13545 folding_initializer = saved_folding_initializer;
13547 tree
13550 {
13551 tree result;
13552 START_FOLD_INIT;
13556 END_FOLD_INIT;
13558 }
13560 tree
13563 {
13564 tree result;
13565 START_FOLD_INIT;
13569 END_FOLD_INIT;
13571 }
13573 tree
13576 {
13577 tree result;
13578 START_FOLD_INIT;
13582 END_FOLD_INIT;
13584 }
13586 #undef START_FOLD_INIT
13587 #undef END_FOLD_INIT
13589 /* Determine if first argument is a multiple of second argument. Return 0 if
13590 it is not, or we cannot easily determined it to be.
13592 An example of the sort of thing we care about (at this point; this routine
13593 could surely be made more general, and expanded to do what the *_DIV_EXPR's
13594 fold cases do now) is discovering that
13596 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13598 is a multiple of
13600 SAVE_EXPR (J * 8)
13602 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13604 This code also handles discovering that
13606 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13608 is a multiple of 8 so we don't have to worry about dealing with a
13609 possible remainder.
13611 Note that we *look* inside a SAVE_EXPR only to determine how it was
13612 calculated; it is not safe for fold to do much of anything else with the
13613 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13614 at run time. For example, the latter example above *cannot* be implemented
13615 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13616 evaluation time of the original SAVE_EXPR is not necessarily the same at
13617 the time the new expression is evaluated. The only optimization of this
13618 sort that would be valid is changing
13620 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13622 divided by 8 to
13624 SAVE_EXPR (I) * SAVE_EXPR (J)
13626 (where the same SAVE_EXPR (J) is used in the original and the
13627 transformed version). */
13629 int
13631 {
13639 {
13641 /* Bitwise and provides a power of two multiple. If the mask is
13642 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13645 /* FALLTHRU */
13658 {
13662 /* const_binop may not detect overflow correctly,
13663 so check for it explicitly here. */
13667 size_one_node,
13668 op1)))
13671 }
13675 /* Can't handle conversions from non-integral or wider integral type. */
13681 /* .. fall through ... */
13698 SIGNED);
13702 }
13703 }
13705 /* Return true if CODE or TYPE is known to be non-negative. */
13707 static bool
13709 {
13712 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
13713 have a signed:1 type (where the value is -1 and 0). */
13716 }
13718 /* Return true if (CODE OP0) is known to be non-negative. If the return
13719 value is based on the assumption that signed overflow is undefined,
13720 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13721 *STRICT_OVERFLOW_P. */
13723 bool
13726 {
13731 {
13733 /* We can't return 1 if flag_wrapv is set because
13734 ABS_EXPR<INT_MIN> = INT_MIN. */
13738 {
13741 }
13748 strict_overflow_p);
13750 CASE_CONVERT:
13751 {
13756 {
13759 strict_overflow_p);
13761 {
13765 strict_overflow_p);
13766 }
13767 }
13769 {
13772 strict_overflow_p);
13776 }
13777 }
13782 }
13784 /* We don't know sign of `t', so be conservative and return false. */
13786 }
13788 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
13789 value is based on the assumption that signed overflow is undefined,
13790 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13791 *STRICT_OVERFLOW_P. */
13793 bool
13796 {
13801 {
13806 strict_overflow_p)
13808 strict_overflow_p));
13810 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13811 both unsigned and at least 2 bits shorter than the result. */
13815 {
13820 {
13824 }
13825 }
13830 {
13831 /* x * x is always non-negative for floating point x
13832 or without overflow. */
13836 {
13841 }
13842 }
13844 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13845 both unsigned and their total bits is shorter than the result. */
13849 {
13868 {
13878 }
13879 }
13885 strict_overflow_p)
13887 strict_overflow_p));
13898 strict_overflow_p)
13900 strict_overflow_p));
13907 strict_overflow_p);
13910 }
13912 /* We don't know sign of `t', so be conservative and return false. */
13914 }
13916 /* Return true if T is known to be non-negative. If the return
13917 value is based on the assumption that signed overflow is undefined,
13918 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13919 *STRICT_OVERFLOW_P. */
13921 bool
13923 {
13928 {
13940 strict_overflow_p)
13942 strict_overflow_p));
13946 }
13947 /* We don't know sign of `t', so be conservative and return false. */
13949 }
13951 /* Return true if T is known to be non-negative. If the return
13952 value is based on the assumption that signed overflow is undefined,
13953 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13954 *STRICT_OVERFLOW_P. */
13956 bool
13959 {
13962 {
13982 /* Always true. */
13986 /* sqrt(-0.0) is -0.0. */
13990 strict_overflow_p);
14027 /* True if the 1st argument is nonnegative. */
14029 strict_overflow_p);
14032 /* True if the 1st OR 2nd arguments are nonnegative. */
14034 strict_overflow_p)
14036 strict_overflow_p)));
14039 /* True if the 1st AND 2nd arguments are nonnegative. */
14041 strict_overflow_p)
14043 strict_overflow_p)));
14046 /* True if the 2nd argument is nonnegative. */
14048 strict_overflow_p);
14051 /* True if the 1st argument is nonnegative or the second
14052 argument is an even integer. */
14057 strict_overflow_p);
14060 /* True if the 1st argument is nonnegative or the second
14061 argument is an even integer valued real. */
14063 {
14064 REAL_VALUE_TYPE c;
14065 HOST_WIDE_INT n;
14070 {
14071 REAL_VALUE_TYPE cint;
14075 }
14076 }
14078 strict_overflow_p);
14082 }
14084 type);
14085 }
14087 /* Return true if T is known to be non-negative. If the return
14088 value is based on the assumption that signed overflow is undefined,
14089 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14090 *STRICT_OVERFLOW_P. */
14092 static bool
14094 {
14100 {
14102 {
14106 /* If the initializer is non-void, then it's a normal expression
14107 that will be assigned to the slot. */
14111 /* Otherwise, the initializer sets the slot in some way. One common
14112 way is an assignment statement at the end of the initializer. */
14114 {
14122 else
14124 }
14128 strict_overflow_p);
14131 }
14134 {
14140 arg0,
14141 arg1,
14142 strict_overflow_p);
14143 }
14147 strict_overflow_p);
14150 strict_overflow_p);
14153 strict_overflow_p);
14158 }
14160 /* We don't know sign of `t', so be conservative and return false. */
14162 }
14164 /* Return true if T is known to be non-negative. If the return
14165 value is based on the assumption that signed overflow is undefined,
14166 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14167 *STRICT_OVERFLOW_P. */
14169 bool
14171 {
14178 {
14185 strict_overflow_p);
14191 strict_overflow_p);
14200 }
14203 {
14211 strict_overflow_p);
14216 strict_overflow_p);
14229 }
14230 }
14232 /* Return true if `t' is known to be non-negative. Handle warnings
14233 about undefined signed overflow. */
14235 bool
14237 {
14244 "determining that expression is always "
14246 WARN_STRICT_OVERFLOW_MISC);
14248 }
14251 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14252 For floating point we further ensure that T is not denormal.
14253 Similar logic is present in nonzero_address in rtlanal.h.
14255 If the return value is based on the assumption that signed overflow
14256 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14257 change *STRICT_OVERFLOW_P. */
14259 bool
14262 {
14264 {
14267 strict_overflow_p);
14270 {
14276 strict_overflow_p));
14277 }
14282 strict_overflow_p);
14286 }
14289 }
14291 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14292 For floating point we further ensure that T is not denormal.
14293 Similar logic is present in nonzero_address in rtlanal.h.
14295 If the return value is based on the assumption that signed overflow
14296 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14297 change *STRICT_OVERFLOW_P. */
14299 bool
14301 tree type,
14302 tree op0,
14304 {
14307 {
14311 {
14312 /* With the presence of negative values it is hard
14313 to say something. */
14320 /* One of operands must be positive and the other non-negative. */
14321 /* We don't set *STRICT_OVERFLOW_P here: even if this value
14322 overflows, on a twos-complement machine the sum of two
14323 nonnegative numbers can never be zero. */
14325 strict_overflow_p)
14327 strict_overflow_p));
14328 }
14333 {
14335 strict_overflow_p)
14337 strict_overflow_p))
14338 {
14341 }
14342 }
14351 {
14354 }
14361 {
14365 /* When both operands are nonzero, then MAX must be too. */
14367 strict_overflow_p))
14370 /* MAX where operand 0 is positive is positive. */
14372 strict_overflow_p);
14373 }
14374 /* MAX where operand 1 is positive is positive. */
14379 {
14383 }
14388 strict_overflow_p)
14390 strict_overflow_p));
14394 }
14397 }
14399 /* Return true when T is an address and is known to be nonzero.
14400 For floating point we further ensure that T is not denormal.
14401 Similar logic is present in nonzero_address in rtlanal.h.
14403 If the return value is based on the assumption that signed overflow
14404 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14405 change *STRICT_OVERFLOW_P. */
14407 bool
14409 {
14412 {
14417 {
14426 /* For objects in symbol table check if we know they are non-zero.
14427 Don't do anything for variables and functions before symtab is built;
14428 it is quite possible that they will be declared weak later. */
14430 {
14436 else
14438 }
14440 /* Function local objects are never NULL. */
14447 /* Constants are never weak. */
14452 }
14460 {
14464 }
14469 }
14471 }
14473 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
14474 attempt to fold the expression to a constant without modifying TYPE,
14475 OP0 or OP1.
14477 If the expression could be simplified to a constant, then return
14478 the constant. If the expression would not be simplified to a
14479 constant, then return NULL_TREE. */
14481 tree
14483 {
14486 }
14488 /* Given the components of a unary expression CODE, TYPE and OP0,
14489 attempt to fold the expression to a constant without modifying
14490 TYPE or OP0.
14492 If the expression could be simplified to a constant, then return
14493 the constant. If the expression would not be simplified to a
14494 constant, then return NULL_TREE. */
14496 tree
14498 {
14501 }
14503 /* If EXP represents referencing an element in a constant string
14504 (either via pointer arithmetic or array indexing), return the
14505 tree representing the value accessed, otherwise return NULL. */
14507 tree
14509 {
14513 {
14515 tree index;
14516 tree string;
14521 else
14522 {
14526 /* Optimize the special-case of a zero lower bound.
14528 We convert the low_bound to sizetype to avoid some problems
14529 with constant folding. (E.g. suppose the lower bound is 1,
14530 and its mode is QI. Without the conversion,l (ARRAY
14531 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
14532 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
14538 }
14551 }
14553 }
14555 /* Return the tree for neg (ARG0) when ARG0 is known to be either
14556 an integer constant, real, or fixed-point constant.
14558 TYPE is the type of the result. */
14560 static tree
14562 {
14566 {
14568 {
14575 }
14582 {
14583 FIXED_VALUE_TYPE f;
14588 /* Propagate overflow flags. */
14592 }
14596 }
14599 }
14601 /* Return the tree for abs (ARG0) when ARG0 is known to be either
14602 an integer constant or real constant.
14604 TYPE is the type of the result. */
14606 tree
14608 {
14612 {
14614 {
14615 /* If the value is unsigned or non-negative, then the absolute value
14616 is the same as the ordinary value. */
14620 /* If the value is negative, then the absolute value is
14621 its negation. */
14622 else
14623 {
14628 }
14629 }
14635 else
14641 }
14644 }
14646 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
14647 constant. TYPE is the type of the result. */
14649 static tree
14651 {
14655 }
14657 /* Given CODE, a relational operator, the target type, TYPE and two
14658 constant operands OP0 and OP1, return the result of the
14659 relational operation. If the result is not a compile time
14660 constant, then return NULL_TREE. */
14662 static tree
14664 {
14667 /* From here on, the only cases we handle are when the result is
14668 known to be a constant. */
14671 {
14675 /* Handle the cases where either operand is a NaN. */
14677 {
14679 {
14707 }
14710 }
14713 }
14716 {
14720 }
14722 /* Handle equality/inequality of complex constants. */
14724 {
14735 else
14737 }
14740 {
14747 {
14759 }
14762 }
14764 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14766 To compute GT, swap the arguments and do LT.
14767 To compute GE, do LT and invert the result.
14768 To compute LE, swap the arguments, do LT and invert the result.
14769 To compute NE, do EQ and invert the result.
14771 Therefore, the code below must handle only EQ and LT. */
14774 {
14777 }
14779 /* Note that it is safe to invert for real values here because we
14780 have already handled the one case that it matters. */
14784 {
14787 }
14789 /* Compute a result for LT or EQ if args permit;
14790 Otherwise return T. */
14792 {
14795 else
14797 }
14798 else
14804 }
14806 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14807 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14808 itself. */
14810 tree
14812 {
14813 /* If the expression does not have side effects then we don't have to wrap
14814 it with a cleanup point expression. */
14818 /* If the expression is a return, check to see if the expression inside the
14819 return has no side effects or the right hand side of the modify expression
14820 inside the return. If either don't have side effects set we don't need to
14821 wrap the expression in a cleanup point expression. Note we don't check the
14822 left hand side of the modify because it should always be a return decl. */
14824 {
14831 }
14834 }
14836 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14837 of an indirection through OP0, or NULL_TREE if no simplification is
14838 possible. */
14840 tree
14842 {
14844 tree subtype;
14852 {
14855 /* *&CONST_DECL -> to the value of the const decl. */
14858 /* *&p => p; make sure to handle *&"str"[cst] here. */
14860 {
14864 else
14866 }
14867 /* *(foo *)&fooarray => fooarray[0] */
14870 && (!in_gimple_form
14872 {
14882 }
14883 /* *(foo *)&complexfoo => __real__ complexfoo */
14887 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14890 {
14894 }
14895 }
14899 {
14905 {
14906 tree op00type;
14910 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14913 {
14925 }
14926 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14929 {
14933 }
14934 /* ((foo *)&fooarray)[1] => fooarray[1] */
14937 {
14947 }
14948 }
14949 }
14951 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14954 && (!in_gimple_form
14956 {
14957 tree type_domain;
14967 NULL_TREE);
14968 }
14971 }
14973 /* Builds an expression for an indirection through T, simplifying some
14974 cases. */
14976 tree
14978 {
14986 }
14988 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14990 tree
14992 {
14997 else
14999 }
15001 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15002 whose result is ignored. The type of the returned tree need not be
15003 the same as the original expression. */
15005 tree
15007 {
15013 {
15024 else
15030 {
15046 }
15051 }
15052 }
15054 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15056 tree
15058 {
15064 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15065 have to do anything. Only do this when we are not given a const,
15066 because in that case, this check is more expensive than just
15067 doing it. */
15069 {
15074 }
15076 /* If divisor is a power of two, simplify this to bit manipulation. */
15078 {
15080 {
15094 }
15095 else
15096 {
15097 tree t;
15103 }
15104 }
15105 else
15106 {
15111 }
15114 }
15116 /* Likewise, but round down. */
15118 tree
15120 {
15127 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15128 have to do anything. Only do this when we are not given a const,
15129 because in that case, this check is more expensive than just
15130 doing it. */
15132 {
15137 }
15139 /* If divisor is a power of two, simplify this to bit manipulation. */
15141 {
15142 tree t;
15146 }
15147 else
15148 {
15153 }
15156 }
15158 /* Returns the pointer to the base of the object addressed by EXP and
15159 extracts the information about the offset of the access, storing it
15160 to PBITPOS and POFFSET. */
15162 static tree
15165 {
15166 tree core;
15167 machine_mode mode;
15169 HOST_WIDE_INT bitsize;
15173 {
15178 }
15179 else
15180 {
15184 }
15187 }
15189 /* Returns true if addresses of E1 and E2 differ by a constant, false
15190 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15192 bool
15194 {
15208 {
15218 }
15220 {
15221 /* If only one of the offsets is non-constant, the difference cannot
15222 be a constant. */
15224 }
15225 else
15230 }
15232 /* Simplify the floating point expression EXP when the sign of the
15233 result is not significant. Return NULL_TREE if no simplification
15234 is possible. */
15236 tree
15238 {
15243 {
15279 {
15282 {
15284 /* Strip copysign function call, return the 1st argument. */
15290 /* Strip sign ops from the argument of "odd" math functions. */
15292 {
15296 }
15298 }
15299 }
15304 }
15306 }
15308 /* Return OFF converted to a pointer offset type suitable as offset for
15309 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
15310 tree
15312 {
15314 }
15316 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
15317 tree
15319 {
15322 }
15324 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
15325 tree
15327 {
15330 }