| blob | 83771207c49bc919eb3e040f54b3b940736e00ac |
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. */
103 /* Nonzero if we are folding constants inside an initializer; zero
104 otherwise. */
107 /* The following constants represent a bit based encoding of GCC's
108 comparison operators. This encoding simplifies transformations
109 on relational comparison operators, such as AND and OR. */
127 };
145 HOST_WIDE_INT *,
178 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
179 Otherwise, return LOC. */
181 static location_t
183 {
186 }
188 /* Similar to protected_set_expr_location, but never modify x in place,
189 if location can and needs to be set, unshare it. */
193 {
199 {
202 }
204 }
205 \f
206 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
207 division and returns the quotient. Otherwise returns
208 NULL_TREE. */
210 tree
212 {
213 widest_int quo;
220 }
221 \f
222 /* This is nonzero if we should defer warnings about undefined
223 overflow. This facility exists because these warnings are a
224 special case. The code to estimate loop iterations does not want
225 to issue any warnings, since it works with expressions which do not
226 occur in user code. Various bits of cleanup code call fold(), but
227 only use the result if it has certain characteristics (e.g., is a
228 constant); that code only wants to issue a warning if the result is
229 used. */
233 /* If a warning about undefined overflow is deferred, this is the
234 warning. Note that this may cause us to turn two warnings into
235 one, but that is fine since it is sufficient to only give one
236 warning per expression. */
240 /* If a warning about undefined overflow is deferred, this is the
241 level at which the warning should be emitted. */
245 /* Start deferring overflow warnings. We could use a stack here to
246 permit nested calls, but at present it is not necessary. */
248 void
250 {
252 }
254 /* Stop deferring overflow warnings. If there is a pending warning,
255 and ISSUE is true, then issue the warning if appropriate. STMT is
256 the statement with which the warning should be associated (used for
257 location information); STMT may be NULL. CODE is the level of the
258 warning--a warn_strict_overflow_code value. This function will use
259 the smaller of CODE and the deferred code when deciding whether to
260 issue the warning. CODE may be zero to mean to always use the
261 deferred code. */
263 void
265 {
267 location_t locus;
272 {
278 }
289 /* Use the smallest code level when deciding to issue the
290 warning. */
299 else
302 }
304 /* Stop deferring overflow warnings, ignoring any deferred
305 warnings. */
307 void
309 {
311 }
313 /* Whether we are deferring overflow warnings. */
315 bool
317 {
319 }
321 /* This is called when we fold something based on the fact that signed
322 overflow is undefined. */
324 static void
326 {
328 {
331 {
334 }
335 }
338 }
339 \f
340 /* Return true if the built-in mathematical function specified by CODE
341 is odd, i.e. -f(x) == f(-x). */
343 static bool
345 {
347 {
381 }
383 }
385 /* Check whether we may negate an integer constant T without causing
386 overflow. */
388 bool
390 {
391 tree type;
400 }
402 /* Determine whether an expression T can be cheaply negated using
403 the function negate_expr without introducing undefined overflow. */
405 static bool
407 {
408 tree type;
417 {
422 /* Check that -CST will not overflow type. */
435 /* We want to canonicalize to positive real constants. Pretend
436 that only negative ones can be easily negated. */
444 {
455 }
468 /* -(A + B) -> (-B) - A. */
473 /* -(A + B) -> (-A) - B. */
477 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
487 /* Fall through. */
498 /* In general we can't negate A / B, because if A is INT_MIN and
499 B is 1, we may turn this into INT_MIN / -1 which is undefined
500 and actually traps on some architectures. But if overflow is
501 undefined, we can negate, because - (INT_MIN / 1) is an
502 overflow. */
504 {
507 /* If overflow is undefined then we have to be careful because
508 we ask whether it's ok to associate the negate with the
509 division which is not ok for example for
510 -((a - b) / c) where (-(a - b)) / c may invoke undefined
511 overflow because of negating INT_MIN. So do not use
512 negate_expr_p here but open-code the two important cases. */
517 }
523 /* Negate -((double)float) as (double)(-float). */
525 {
529 }
533 /* Negate -f(x) as f(-x). */
539 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
541 {
545 }
550 }
552 }
554 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
555 simplification is possible.
556 If negate_expr_p would return true for T, NULL_TREE will never be
557 returned. */
559 static tree
561 {
563 tree tem;
566 {
567 /* Convert - (~A) to A + 1. */
593 {
598 }
602 {
607 {
611 }
614 }
637 {
638 /* -(A + B) -> (-B) - A. */
642 {
646 }
648 /* -(A + B) -> (-A) - B. */
650 {
654 }
655 }
659 /* - (A - B) -> B - A */
671 /* Fall through. */
675 {
684 }
690 /* In general we can't negate A / B, because if A is INT_MIN and
691 B is 1, we may turn this into INT_MIN / -1 which is undefined
692 and actually traps on some architectures. But if overflow is
693 undefined, we can negate, because - (INT_MIN / 1) is an
694 overflow. */
696 {
701 {
708 }
709 /* If overflow is undefined then we have to be careful because
710 we ask whether it's ok to associate the negate with the
711 division which is not ok for example for
712 -((a - b) / c) where (-(a - b)) / c may invoke undefined
713 overflow because of negating INT_MIN. So do not use
714 negate_expr_p here but open-code the two important cases. */
723 }
727 /* Convert -((double)float) into (double)(-float). */
729 {
733 }
737 /* Negate -f(x) as f(-x). */
740 {
746 }
750 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
752 {
755 {
762 }
763 }
768 }
771 }
773 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
774 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
775 return NULL_TREE. */
777 static tree
779 {
781 location_t loc;
794 }
795 \f
796 /* Split a tree IN into a constant, literal and variable parts that could be
797 combined with CODE to make IN. "constant" means an expression with
798 TREE_CONSTANT but that isn't an actual constant. CODE must be a
799 commutative arithmetic operation. Store the constant part into *CONP,
800 the literal in *LITP and return the variable part. If a part isn't
801 present, set it to null. If the tree does not decompose in this way,
802 return the entire tree as the variable part and the other parts as null.
804 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
805 case, we negate an operand that was subtracted. Except if it is a
806 literal for which we use *MINUS_LITP instead.
808 If NEGATE_P is true, we are negating all of IN, again except a literal
809 for which we use *MINUS_LITP instead.
811 If IN is itself a literal or constant, return it as appropriate.
813 Note that we do not guarantee that any of the three values will be the
814 same type as IN, but they will have the same signedness and mode. */
816 static tree
819 {
826 /* Strip any conversions that don't change the machine mode or signedness. */
835 /* We can associate addition and subtraction together (even
836 though the C standard doesn't say so) for integers because
837 the value is not affected. For reals, the value might be
838 affected, so we can't. */
841 {
847 /* First see if either of the operands is a literal, then a constant. */
860 /* If we haven't dealt with either operand, this is not a case we can
861 decompose. Otherwise, VAR is either of the ones remaining, if any. */
866 else
869 /* Now do any needed negations. */
876 }
879 {
880 /* -X - 1 is folded to ~X, undo that here. */
883 }
886 else
890 {
897 }
900 }
902 /* Re-associate trees split by the above function. T1 and T2 are
903 either expressions to associate or null. Return the new
904 expression, if any. LOC is the location of the new expression. If
905 we build an operation, do it in TYPE and with CODE. */
907 static tree
909 {
915 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
916 try to fold this since we will have infinite recursion. But do
917 deal with any NEGATE_EXPRs. */
920 {
922 {
935 }
937 {
940 }
944 }
948 }
949 \f
950 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
951 for use in int_const_binop, size_binop and size_diffop. */
953 static bool
955 {
962 {
971 }
976 }
979 /* Combine two integer constants ARG1 and ARG2 under operation CODE
980 to produce a new constant. Return NULL_TREE if we don't know how
981 to evaluate CODE at compile-time. */
983 static tree
986 {
987 wide_int res;
988 tree t;
997 {
1013 {
1017 else
1019 }
1022 /* It's unclear from the C standard whether shifts can overflow.
1023 The following code ignores overflow; perhaps a C standard
1024 interpretation ruling is needed. */
1026 else
1033 {
1037 else
1039 }
1043 else
1122 }
1130 }
1132 tree
1134 {
1136 }
1138 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1139 constant. We assume ARG1 and ARG2 have the same data type, or at least
1140 are the same kind of constant and the same machine mode. Return zero if
1141 combining the constants is not allowed in the current operating mode. */
1143 static tree
1145 {
1146 /* Sanity check for the recursive cases. */
1154 {
1160 }
1163 {
1164 machine_mode mode;
1165 REAL_VALUE_TYPE d1;
1166 REAL_VALUE_TYPE d2;
1167 REAL_VALUE_TYPE value;
1168 REAL_VALUE_TYPE result;
1172 /* The following codes are handled by real_arithmetic. */
1174 {
1185 }
1193 /* Don't perform operation if we honor signaling NaNs and
1194 either operand is a NaN. */
1199 /* Don't perform operation if it would raise a division
1200 by zero exception. */
1206 /* If either operand is a NaN, just return it. Otherwise, set up
1207 for floating-point trap; we return an overflow. */
1216 /* Don't constant fold this floating point operation if
1217 the result has overflowed and flag_trapping_math. */
1225 /* Don't constant fold this floating point operation if the
1226 result may dependent upon the run-time rounding mode and
1227 flag_rounding_math is set, or if GCC's software emulation
1228 is unable to accurately represent the result. */
1238 }
1241 {
1242 FIXED_VALUE_TYPE f1;
1243 FIXED_VALUE_TYPE f2;
1244 FIXED_VALUE_TYPE result;
1249 /* The following codes are handled by fixed_arithmetic. */
1251 {
1263 {
1270 }
1275 }
1282 /* Propagate overflow flags. */
1286 }
1289 {
1298 {
1309 mpc_mul);
1323 mpc_div);
1324 /* Fallthru ... */
1330 {
1331 /* Keep this algorithm in sync with
1332 tree-complex.c:expand_complex_div_straight().
1334 Expand complex division to scalars, straightforward algorithm.
1335 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1336 t = br*br + bi*bi
1337 */
1338 tree magsquared
1342 tree t1
1346 tree t2
1353 }
1354 else
1355 {
1356 /* Keep this algorithm in sync with
1357 tree-complex.c:expand_complex_div_wide().
1359 Expand complex division to scalars, modified algorithm to minimize
1360 overflow with wide input ranges. */
1366 {
1367 /* In the TRUE branch, we compute
1368 ratio = br/bi;
1369 div = (br * ratio) + bi;
1370 tr = (ar * ratio) + ai;
1371 ti = (ai * ratio) - ar;
1372 tr = tr / div;
1373 ti = ti / div; */
1384 }
1385 else
1386 {
1387 /* In the FALSE branch, we compute
1388 ratio = d/c;
1389 divisor = (d * ratio) + c;
1390 tr = (b * ratio) + a;
1391 ti = b - (a * ratio);
1392 tr = tr / div;
1393 ti = ti / div; */
1405 }
1406 }
1411 }
1415 }
1419 {
1425 {
1431 /* It is possible that const_binop cannot handle the given
1432 code and return NULL_TREE */
1435 }
1438 }
1440 /* Shifts allow a scalar offset for a vector. */
1443 {
1449 {
1454 /* It is possible that const_binop cannot handle the given
1455 code and return NULL_TREE. */
1458 }
1461 }
1463 }
1465 /* Overload that adds a TYPE parameter to be able to dispatch
1466 to fold_relational_const. */
1468 tree
1470 {
1474 /* ??? Until we make the const_binop worker take the type of the
1475 result as argument put those cases that need it here. */
1477 {
1488 {
1504 {
1510 }
1513 }
1519 {
1544 {
1557 }
1560 }
1563 }
1568 /* Make sure type and arg0 have the same saturating flag. */
1573 }
1575 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1576 Return zero if computing the constants is not possible. */
1578 tree
1580 {
1582 {
1583 CASE_CONVERT:
1598 {
1599 /* Can't call fold_negate_const directly here as that doesn't
1600 handle all cases and we might not be able to negate some
1601 constants. */
1606 }
1615 {
1619 }
1625 /* Perform BIT_NOT_EXPR on each element individually. */
1627 {
1629 tree elem;
1634 {
1640 }
1643 }
1665 {
1684 else
1688 {
1692 }
1695 }
1700 {
1714 {
1719 }
1722 {
1726 }
1729 }
1733 }
1736 }
1738 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1739 indicates which particular sizetype to create. */
1741 tree
1743 {
1745 }
1746 \f
1747 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1748 is a tree code. The type of the result is taken from the operands.
1749 Both must be equivalent integer types, ala int_binop_types_match_p.
1750 If the operands are constant, so is the result. */
1752 tree
1754 {
1763 /* Handle the special case of two integer constants faster. */
1765 {
1766 /* And some specific cases even faster than that. */
1768 {
1773 }
1775 {
1778 }
1780 {
1783 }
1785 /* Handle general case of two integer constants. For sizetype
1786 constant calculations we always want to know about overflow,
1787 even in the unsigned case. */
1789 }
1792 }
1794 /* Given two values, either both of sizetype or both of bitsizetype,
1795 compute the difference between the two values. Return the value
1796 in signed type corresponding to the type of the operands. */
1798 tree
1800 {
1802 tree ctype;
1807 /* If the type is already signed, just do the simple thing. */
1815 else
1818 /* If either operand is not a constant, do the conversions to the signed
1819 type and subtract. The hardware will do the right thing with any
1820 overflow in the subtraction. */
1826 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1827 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1828 overflow) and negate (which can't either). Special-case a result
1829 of zero while we're here. */
1835 else
1839 MINUS_EXPR,
1841 }
1842 \f
1843 /* A subroutine of fold_convert_const handling conversions of an
1844 INTEGER_CST to another integer type. */
1846 static tree
1848 {
1849 /* Given an integer constant, make new constant with new type,
1850 appropriately sign-extended or truncated. Use widest_int
1851 so that any extension is done according ARG1's type. */
1855 }
1857 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1858 to an integer type. */
1860 static tree
1862 {
1864 tree t;
1866 /* The following code implements the floating point to integer
1867 conversion rules required by the Java Language Specification,
1868 that IEEE NaNs are mapped to zero and values that overflow
1869 the target precision saturate, i.e. values greater than
1870 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1871 are mapped to INT_MIN. These semantics are allowed by the
1872 C and C++ standards that simply state that the behavior of
1873 FP-to-integer conversion is unspecified upon overflow. */
1875 wide_int val;
1876 REAL_VALUE_TYPE r;
1880 {
1887 }
1889 /* If R is NaN, return zero and show we have an overflow. */
1891 {
1894 }
1896 /* See if R is less than the lower bound or greater than the
1897 upper bound. */
1900 {
1904 {
1907 }
1908 }
1911 {
1914 {
1917 {
1920 }
1921 }
1922 }
1929 }
1931 /* A subroutine of fold_convert_const handling conversions of a
1932 FIXED_CST to an integer type. */
1934 static tree
1936 {
1937 tree t;
1941 /* Right shift FIXED_CST to temp by fbit. */
1945 {
1947 HOST_BITS_PER_DOUBLE_INT,
1950 /* Left shift temp to temp_trunc by fbit. */
1952 HOST_BITS_PER_DOUBLE_INT,
1954 }
1955 else
1956 {
1959 }
1961 /* If FIXED_CST is negative, we need to round the value toward 0.
1962 By checking if the fractional bits are not zero to add 1 to temp. */
1968 /* Given a fixed-point constant, make new constant with new type,
1969 appropriately sign-extended or truncated. */
1977 }
1979 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1980 to another floating point type. */
1982 static tree
1984 {
1985 REAL_VALUE_TYPE value;
1986 tree t;
1991 /* If converting an infinity or NAN to a representation that doesn't
1992 have one, set the overflow bit so that we can produce some kind of
1993 error message at the appropriate point if necessary. It's not the
1994 most user-friendly message, but it's better than nothing. */
2001 /* Regular overflow, conversion produced an infinity in a mode that
2002 can't represent them. */
2007 else
2010 }
2012 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2013 to a floating point type. */
2015 static tree
2017 {
2018 REAL_VALUE_TYPE value;
2019 tree t;
2026 }
2028 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2029 to another fixed-point type. */
2031 static tree
2033 {
2034 FIXED_VALUE_TYPE value;
2035 tree t;
2042 /* Propagate overflow flags. */
2046 }
2048 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2049 to a fixed-point type. */
2051 static tree
2053 {
2054 FIXED_VALUE_TYPE value;
2055 tree t;
2057 double_int di;
2064 else
2072 /* Propagate overflow flags. */
2076 }
2078 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2079 to a fixed-point type. */
2081 static tree
2083 {
2084 FIXED_VALUE_TYPE value;
2085 tree t;
2093 /* Propagate overflow flags. */
2097 }
2099 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2100 type TYPE. If no simplification can be done return NULL_TREE. */
2102 static tree
2104 {
2110 {
2117 }
2119 {
2126 }
2128 {
2135 }
2137 }
2139 /* Construct a vector of zero elements of vector type TYPE. */
2141 static tree
2143 {
2144 tree t;
2148 }
2150 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2152 bool
2154 {
2169 {
2188 }
2189 }
2191 /* Convert expression ARG to type TYPE. Used by the middle-end for
2192 simple conversions in preference to calling the front-end's convert. */
2194 tree
2196 {
2198 tree tem;
2209 {
2212 /* Handle conversions between pointers to different address spaces. */
2217 /* fall through */
2222 {
2226 }
2240 {
2244 }
2246 {
2250 }
2252 {
2256 }
2259 {
2277 }
2282 {
2286 }
2289 {
2303 }
2307 {
2316 integer_zero_node));
2318 {
2322 {
2328 }
2336 }
2340 }
2358 }
2359 fold_convert_exit:
2362 }
2363 \f
2364 /* Return false if expr can be assumed not to be an lvalue, true
2365 otherwise. */
2367 static bool
2369 {
2370 /* We only need to wrap lvalue tree codes. */
2372 {
2403 /* Assume the worst for front-end tree codes. */
2407 }
2410 }
2412 /* Return an expr equal to X but certainly not valid as an lvalue. */
2414 tree
2416 {
2417 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2418 us. */
2425 }
2427 /* When pedantic, return an expr equal to X but certainly not valid as a
2428 pedantic lvalue. Otherwise, return X. */
2430 static tree
2432 {
2434 }
2435 \f
2436 /* Given a tree comparison code, return the code that is the logical inverse.
2437 It is generally not safe to do this for floating-point comparisons, except
2438 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2439 ERROR_MARK in this case. */
2441 enum tree_code
2443 {
2449 {
2480 }
2481 }
2483 /* Similar, but return the comparison that results if the operands are
2484 swapped. This is safe for floating-point. */
2486 enum tree_code
2488 {
2490 {
2516 }
2517 }
2520 /* Convert a comparison tree code from an enum tree_code representation
2521 into a compcode bit-based encoding. This function is the inverse of
2522 compcode_to_comparison. */
2524 static enum comparison_code
2526 {
2528 {
2559 }
2560 }
2562 /* Convert a compcode bit-based encoding of a comparison operator back
2563 to GCC's enum tree_code representation. This function is the
2564 inverse of comparison_to_compcode. */
2566 static enum tree_code
2568 {
2570 {
2601 }
2602 }
2604 /* Return a tree for the comparison which is the combination of
2605 doing the AND or OR (depending on CODE) of the two operations LCODE
2606 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2607 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2608 if this makes the transformation invalid. */
2610 tree
2615 {
2622 {
2633 }
2636 {
2637 /* Eliminate unordered comparisons, as well as LTGT and ORD
2638 which are not used unless the mode has NaNs. */
2644 }
2646 {
2647 /* Check that the original operation and the optimized ones will trap
2648 under the same condition. */
2659 /* In a short-circuited boolean expression the LHS might be
2660 such that the RHS, if evaluated, will never trap. For
2661 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2662 if neither x nor y is NaN. (This is a mixed blessing: for
2663 example, the expression above will never trap, hence
2664 optimizing it to x < y would be invalid). */
2669 /* If the comparison was short-circuited, and only the RHS
2670 trapped, we may now generate a spurious trap. */
2675 /* If we changed the conditions that cause a trap, we lose. */
2678 }
2684 else
2685 {
2690 }
2691 }
2692 \f
2693 /* Return nonzero if two operands (typically of the same tree node)
2694 are necessarily equal. If either argument has side-effects this
2695 function returns zero. FLAGS modifies behavior as follows:
2697 If OEP_ONLY_CONST is set, only return nonzero for constants.
2698 This function tests whether the operands are indistinguishable;
2699 it does not test whether they are equal using C's == operation.
2700 The distinction is important for IEEE floating point, because
2701 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2702 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2704 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2705 even though it may hold multiple values during a function.
2706 This is because a GCC tree node guarantees that nothing else is
2707 executed between the evaluation of its "operands" (which may often
2708 be evaluated in arbitrary order). Hence if the operands themselves
2709 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2710 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2711 unset means assuming isochronic (or instantaneous) tree equivalence.
2712 Unless comparing arbitrary expression trees, such as from different
2713 statements, this flag can usually be left unset.
2715 If OEP_PURE_SAME is set, then pure functions with identical arguments
2716 are considered the same. It is used when the caller has other ways
2717 to ensure that global memory is unchanged in between. */
2719 int
2721 {
2722 /* If either is ERROR_MARK, they aren't equal. */
2728 /* Similar, if either does not have a type (like a released SSA name),
2729 they aren't equal. */
2733 /* Check equality of integer constants before bailing out due to
2734 precision differences. */
2738 /* If both types don't have the same signedness, then we can't consider
2739 them equal. We must check this before the STRIP_NOPS calls
2740 because they may change the signedness of the arguments. As pointers
2741 strictly don't have a signedness, require either two pointers or
2742 two non-pointers as well. */
2747 /* We cannot consider pointers to different address space equal. */
2753 /* If both types don't have the same precision, then it is not safe
2754 to strip NOPs. */
2762 /* In case both args are comparisons but with different comparison
2763 code, try to swap the comparison operands of one arg to produce
2764 a match and compare that variant. */
2768 {
2776 }
2779 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2783 /* This is needed for conversions and for COMPONENT_REF.
2784 Might as well play it safe and always test this. */
2790 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2791 We don't care about side effects in that case because the SAVE_EXPR
2792 takes care of that for us. In all other cases, two expressions are
2793 equal if they have no side effects. If we have two identical
2794 expressions with side effects that should be treated the same due
2795 to the only side effects being identical SAVE_EXPR's, that will
2796 be detected in the recursive calls below.
2797 If we are taking an invariant address of two identical objects
2798 they are necessarily equal as well. */
2805 /* Next handle constant cases, those for which we can return 1 even
2806 if ONLY_CONST is set. */
2809 {
2824 {
2825 /* If we do not distinguish between signed and unsigned zero,
2826 consider them equal. */
2829 }
2833 {
2840 {
2844 }
2846 }
2850 flags)
2852 flags));
2866 }
2871 /* Define macros to test an operand from arg0 and arg1 for equality and a
2872 variant that allows null and views null as being different from any
2873 non-null value. In the latter case, if either is null, the both
2874 must be; otherwise, do the normal comparison. */
2875 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2876 TREE_OPERAND (arg1, N), flags)
2878 #define OP_SAME_WITH_NULL(N) \
2879 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2880 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2883 {
2885 /* Two conversions are equal only if signedness and modes match. */
2887 {
2888 CASE_CONVERT:
2896 }
2906 /* For commutative ops, allow the other order. */
2914 /* If either of the pointer (or reference) expressions we are
2915 dereferencing contain a side effect, these cannot be equal,
2916 but their addresses can be. */
2923 {
2934 /* Require equal extra operands and then fall through to MEM_REF
2935 handling of the two common operands. */
2940 /* Fallthru. */
2943 /* Require equal access sizes, and similar pointer types.
2944 We can have incomplete types for array references of
2945 variable-sized arrays from the Fortran frontend
2946 though. Also verify the types are compatible. */
2953 && alias_ptr_types_compatible_p
2960 /* Operands 2 and 3 may be null.
2961 Compare the array index by value if it is constant first as we
2962 may have different types but same value here. */
2973 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2974 may be NULL when we're called to compare MEM_EXPRs. */
2989 }
2993 {
3007 /* The multiplcation operands are commutative. */
3008 /* FALLTHRU */
3016 /* Otherwise take into account this is a commutative operation. */
3029 }
3033 {
3035 /* If the CALL_EXPRs call different functions, then they
3036 clearly can not be equal. */
3038 flags))
3041 {
3045 else
3049 }
3051 /* Now see if all the arguments are the same. */
3052 {
3063 /* If we get here and both argument lists are exhausted
3064 then the CALL_EXPRs are equal. */
3066 }
3069 }
3072 /* Consider __builtin_sqrt equal to sqrt. */
3080 }
3082 #undef OP_SAME
3083 #undef OP_SAME_WITH_NULL
3084 }
3085 \f
3086 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3087 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3089 When in doubt, return 0. */
3091 static int
3093 {
3105 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3106 and see if the inner values are the same. This removes any
3107 signedness comparison, which doesn't matter here. */
3114 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3115 actual comparison operand, ARG0.
3117 First throw away any conversions to wider types
3118 already present in the operands. */
3127 {
3130 /* Make sure shorter operand is extended the right way
3131 to match the longer operand. */
3137 }
3140 }
3141 \f
3142 /* See if ARG is an expression that is either a comparison or is performing
3143 arithmetic on comparisons. The comparisons must only be comparing
3144 two different values, which will be stored in *CVAL1 and *CVAL2; if
3145 they are nonzero it means that some operands have already been found.
3146 No variables may be used anywhere else in the expression except in the
3147 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3148 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3150 If this is true, return 1. Otherwise, return zero. */
3152 static int
3154 {
3158 /* We can handle some of the tcc_expression cases here. */
3168 {
3169 /* If we've already found a CVAL1 or CVAL2, this expression is
3170 two complex to handle. */
3176 }
3179 {
3202 /* First see if we can handle the first operand, then the second. For
3203 the second operand, we know *CVAL1 can't be zero. It must be that
3204 one side of the comparison is each of the values; test for the
3205 case where this isn't true by failing if the two operands
3206 are the same. */
3215 ;
3219 ;
3220 else
3224 ;
3228 ;
3229 else
3236 }
3237 }
3238 \f
3239 /* ARG is a tree that is known to contain just arithmetic operations and
3240 comparisons. Evaluate the operations in the tree substituting NEW0 for
3241 any occurrence of OLD0 as an operand of a comparison and likewise for
3242 NEW1 and OLD1. */
3244 static tree
3247 {
3252 /* We can handle some of the tcc_expression cases here. */
3260 {
3275 {
3294 }
3295 /* Fall through - ??? */
3298 {
3302 /* We need to check both for exact equality and tree equality. The
3303 former will be true if the operand has a side-effect. In that
3304 case, we know the operand occurred exactly once. */
3317 }
3321 }
3322 }
3323 \f
3324 /* Return a tree for the case when the result of an expression is RESULT
3325 converted to TYPE and OMITTED was previously an operand of the expression
3326 but is now not needed (e.g., we folded OMITTED * 0).
3328 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3329 the conversion of RESULT to TYPE. */
3331 tree
3333 {
3336 /* If the resulting operand is an empty statement, just return the omitted
3337 statement casted to void. */
3347 }
3349 /* Return a tree for the case when the result of an expression is RESULT
3350 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3351 of the expression but are now not needed.
3353 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3354 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3355 evaluated before OMITTED2. Otherwise, if neither has side effects,
3356 just do the conversion of RESULT to TYPE. */
3358 tree
3361 {
3370 }
3372 \f
3373 /* Return a simplified tree node for the truth-negation of ARG. This
3374 never alters ARG itself. We assume that ARG is an operation that
3375 returns a truth value (0 or 1).
3377 FIXME: one would think we would fold the result, but it causes
3378 problems with the dominator optimizer. */
3380 static tree
3382 {
3387 /* If this is a comparison, we can simply invert it, except for
3388 floating-point non-equality comparisons, in which case we just
3389 enclose a TRUTH_NOT_EXPR around what we have. */
3392 {
3395 && flag_trapping_math
3406 }
3409 {
3428 /* Here we can invert either operand. We invert the first operand
3429 unless the second operand is a TRUTH_NOT_EXPR in which case our
3430 result is the XOR of the first operand with the inside of the
3431 negation of the second operand. */
3436 else
3459 {
3466 /* A COND_EXPR may have a throw as one operand, which
3467 then has void type. Just leave void operands
3468 as they are. */
3474 }
3486 CASE_CONVERT:
3490 /* ... fall through ... */
3512 }
3513 }
3515 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3516 assume that ARG is an operation that returns a truth value (0 or 1
3517 for scalars, 0 or -1 for vectors). Return the folded expression if
3518 folding is successful. Otherwise, return NULL_TREE. */
3520 static tree
3522 {
3525 ? BIT_NOT_EXPR
3528 }
3530 /* Return a simplified tree node for the truth-negation of ARG. This
3531 never alters ARG itself. We assume that ARG is an operation that
3532 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3534 tree
3536 {
3542 ? BIT_NOT_EXPR
3545 }
3547 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3548 operands are another bit-wise operation with a common input. If so,
3549 distribute the bit operations to save an operation and possibly two if
3550 constants are involved. For example, convert
3551 (A | B) & (A | C) into A | (B & C)
3552 Further simplification will occur if B and C are constants.
3554 If this optimization cannot be done, 0 will be returned. */
3556 static tree
3559 {
3560 tree common;
3570 {
3574 }
3576 {
3580 }
3582 {
3586 }
3588 {
3592 }
3593 else
3601 }
3603 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3604 with code CODE. This optimization is unsafe. */
3605 static tree
3608 {
3612 /* (A / C) +- (B / C) -> (A +- B) / C. */
3622 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3627 {
3639 }
3642 }
3643 \f
3644 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3645 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3647 static tree
3650 {
3654 {
3661 }
3675 }
3677 /* Optimize a bit-field compare.
3679 There are two cases: First is a compare against a constant and the
3680 second is a comparison of two items where the fields are at the same
3681 bit position relative to the start of a chunk (byte, halfword, word)
3682 large enough to contain it. In these cases we can avoid the shift
3683 implicit in bitfield extractions.
3685 For constants, we emit a compare of the shifted constant with the
3686 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3687 compared. For two fields at the same position, we do the ANDs with the
3688 similar mask and compare the result of the ANDs.
3690 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3691 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3692 are the left and right operands of the comparison, respectively.
3694 If the optimization described above can be done, we return the resulting
3695 tree. Otherwise we return zero. */
3697 static tree
3700 {
3703 tree unsigned_type;
3709 tree mask;
3710 tree offset;
3712 /* Get all the information about the extractions being done. If the bit size
3713 if the same as the size of the underlying object, we aren't doing an
3714 extraction at all and so can do nothing. We also don't want to
3715 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3716 then will no longer be able to replace it. */
3724 {
3725 /* If this is not a constant, we can only do something if bit positions,
3726 sizes, and signedness are the same. */
3734 }
3736 /* See if we can find a mode to refer to this field. We should be able to,
3737 but fail if we can't. */
3746 /* Set signed and unsigned types of the precision of this mode for the
3747 shifts below. */
3750 /* Compute the bit position and size for the new reference and our offset
3751 within it. If the new reference is the same size as the original, we
3752 won't optimize anything, so return zero. */
3762 /* Make the mask to be used against the extracted field. */
3769 /* If not comparing with constant, just rework the comparison
3770 and return. */
3774 unsigned_type,
3777 mask),
3780 unsigned_type,
3783 mask));
3785 /* Otherwise, we are handling the constant case. See if the constant is too
3786 big for the field. Warn and return a tree of for 0 (false) if so. We do
3787 this not only for its own sake, but to avoid having to test for this
3788 error case below. If we didn't, we might generate wrong code.
3790 For unsigned fields, the constant shifted right by the field length should
3791 be all zero. For signed fields, the high-order bits should agree with
3792 the sign bit. */
3795 {
3797 {
3801 }
3802 }
3803 else
3804 {
3807 {
3811 }
3812 }
3814 /* Single-bit compares should always be against zero. */
3816 {
3819 }
3821 /* Make a new bitfield reference, shift the constant over the
3822 appropriate number of bits and mask it with the computed mask
3823 (in case this was a signed field). If we changed it, make a new one. */
3830 mask);
3835 }
3836 \f
3837 /* Subroutine for fold_truth_andor_1: decode a field reference.
3839 If EXP is a comparison reference, we return the innermost reference.
3841 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3842 set to the starting bit number.
3844 If the innermost field can be completely contained in a mode-sized
3845 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3847 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3848 otherwise it is not changed.
3850 *PUNSIGNEDP is set to the signedness of the field.
3852 *PMASK is set to the mask used. This is either contained in a
3853 BIT_AND_EXPR or derived from the width of the field.
3855 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3857 Return 0 if this is not a component reference or is one that we can't
3858 do anything with. */
3860 static tree
3865 {
3869 tree unsigned_type;
3872 /* All the optimizations using this function assume integer fields.
3873 There are problems with FP fields since the type_for_size call
3874 below can fail for, e.g., XFmode. */
3878 /* We are interested in the bare arrangement of bits, so strip everything
3879 that doesn't affect the machine mode. However, record the type of the
3880 outermost expression if it may matter below. */
3887 {
3893 }
3902 /* If the number of bits in the reference is the same as the bitsize of
3903 the outer type, then the outer type gives the signedness. Otherwise
3904 (in case of a small bitfield) the signedness is unchanged. */
3908 /* Compute the mask to access the bitfield. */
3917 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3925 }
3927 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3928 bit positions and MASK is SIGNED. */
3930 static int
3932 {
3936 /* If this function returns true when the type of the mask is
3937 UNSIGNED, then there will be errors. In particular see
3938 gcc.c-torture/execute/990326-1.c. There does not appear to be
3939 any documentation paper trail as to why this is so. But the pre
3940 wide-int worked with that restriction and it has been preserved
3941 here. */
3946 }
3948 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3949 represents the sign bit of EXP's type. If EXP represents a sign
3950 or zero extension, also test VAL against the unextended type.
3951 The return value is the (sub)expression whose sign bit is VAL,
3952 or NULL_TREE otherwise. */
3954 tree
3956 {
3958 tree t;
3960 /* Tree EXP must have an integral type. */
3965 /* Tree VAL must be an integer constant. */
3974 /* Handle extension from a narrower type. */
3980 }
3982 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3983 to be evaluated unconditionally. */
3985 static int
3987 {
3988 /* Strip any conversions that don't change the machine mode. */
3997 /* Don't regard global variables as simple. They may be
3998 allocated in ways unknown to the compiler (shared memory,
3999 #pragma weak, etc). */
4002 /* Weakrefs are not safe to be read, since they can be NULL.
4003 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4004 have DECL_WEAK flag set. */
4006 /* Loading a static variable is unduly expensive, but global
4007 registers aren't expensive. */
4009 }
4011 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4012 to be evaluated unconditionally.
4013 I addition to simple_operand_p, we assume that comparisons, conversions,
4014 and logic-not operations are simple, if their operands are simple, too. */
4016 static bool
4018 {
4038 }
4040 \f
4041 /* The following functions are subroutines to fold_range_test and allow it to
4042 try to change a logical combination of comparisons into a range test.
4044 For example, both
4045 X == 2 || X == 3 || X == 4 || X == 5
4046 and
4047 X >= 2 && X <= 5
4048 are converted to
4049 (unsigned) (X - 2) <= 3
4051 We describe each set of comparisons as being either inside or outside
4052 a range, using a variable named like IN_P, and then describe the
4053 range with a lower and upper bound. If one of the bounds is omitted,
4054 it represents either the highest or lowest value of the type.
4056 In the comments below, we represent a range by two numbers in brackets
4057 preceded by a "+" to designate being inside that range, or a "-" to
4058 designate being outside that range, so the condition can be inverted by
4059 flipping the prefix. An omitted bound is represented by a "-". For
4060 example, "- [-, 10]" means being outside the range starting at the lowest
4061 possible value and ending at 10, in other words, being greater than 10.
4062 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4063 always false.
4065 We set up things so that the missing bounds are handled in a consistent
4066 manner so neither a missing bound nor "true" and "false" need to be
4067 handled using a special case. */
4069 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4070 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4071 and UPPER1_P are nonzero if the respective argument is an upper bound
4072 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4073 must be specified for a comparison. ARG1 will be converted to ARG0's
4074 type if both are specified. */
4076 static tree
4079 {
4080 tree tem;
4084 /* If neither arg represents infinity, do the normal operation.
4085 Else, if not a comparison, return infinity. Else handle the special
4086 comparison rules. Note that most of the cases below won't occur, but
4087 are handled for consistency. */
4090 {
4095 }
4100 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4101 for neither. In real maths, we cannot assume open ended ranges are
4102 the same. But, this is computer arithmetic, where numbers are finite.
4103 We can therefore make the transformation of any unbounded range with
4104 the value Z, Z being greater than any representable number. This permits
4105 us to treat unbounded ranges as equal. */
4109 {
4130 }
4133 }
4134 \f
4135 /* Helper routine for make_range. Perform one step for it, return
4136 new expression if the loop should continue or NULL_TREE if it should
4137 stop. */
4139 tree
4143 {
4149 {
4151 /* We can only do something if the range is testing for zero. */
4160 /* We can only do something if the range is testing for zero
4161 and if the second operand is an integer constant. Note that
4162 saying something is "in" the range we make is done by
4163 complementing IN_P since it will set in the initial case of
4164 being not equal to zero; "out" is leaving it alone. */
4171 {
4192 }
4194 /* If this is an unsigned comparison, we also know that EXP is
4195 greater than or equal to zero. We base the range tests we make
4196 on that fact, so we record it here so we can parse existing
4197 range tests. We test arg0_type since often the return type
4198 of, e.g. EQ_EXPR, is boolean. */
4200 {
4204 NULL_TREE))
4209 /* If the high bound is missing, but we have a nonzero low
4210 bound, reverse the range so it goes from zero to the low bound
4211 minus 1. */
4213 {
4218 }
4219 }
4227 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4228 low and high are non-NULL, then normalize will DTRT. */
4231 {
4236 }
4238 /* (-x) IN [a,b] -> x in [-b, -a] */
4250 /* ~ X -> -X - 1 */
4259 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4260 move a constant to the other side. */
4265 /* If EXP is signed, any overflow in the computation is undefined,
4266 so we don't worry about it so long as our computations on
4267 the bounds don't overflow. For unsigned, overflow is defined
4268 and this is exactly the right thing. */
4280 normalize:
4281 /* Check for an unsigned range which has wrapped around the maximum
4282 value thus making n_high < n_low, and normalize it. */
4284 {
4290 /* If the range is of the form +/- [ x+1, x ], we won't
4291 be able to normalize it. But then, it represents the
4292 whole range or the empty set, so make it
4293 +/- [ -, - ]. */
4297 else
4299 }
4300 else
4308 CASE_CONVERT:
4326 /* If we're converting arg0 from an unsigned type, to exp,
4327 a signed type, we will be doing the comparison as unsigned.
4328 The tests above have already verified that LOW and HIGH
4329 are both positive.
4331 So we have to ensure that we will handle large unsigned
4332 values the same way that the current signed bounds treat
4333 negative values. */
4336 {
4337 tree high_positive;
4338 tree equiv_type;
4339 /* For fixed-point modes, we need to pass the saturating flag
4340 as the 2nd parameter. */
4342 equiv_type
4345 else
4346 equiv_type
4349 /* A range without an upper bound is, naturally, unbounded.
4350 Since convert would have cropped a very large value, use
4351 the max value for the destination type. */
4352 high_positive
4359 high_positive),
4362 /* If the low bound is specified, "and" the range with the
4363 range for which the original unsigned value will be
4364 positive. */
4366 {
4369 integer_zero_node),
4370 high_positive))
4374 }
4375 else
4376 {
4377 /* Otherwise, "or" the range with the range of the input
4378 that will be interpreted as negative. */
4381 integer_zero_node),
4382 high_positive))
4386 }
4387 }
4396 }
4397 }
4399 /* Given EXP, a logical expression, set the range it is testing into
4400 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4401 actually being tested. *PLOW and *PHIGH will be made of the same
4402 type as the returned expression. If EXP is not a comparison, we
4403 will most likely not be returning a useful value and range. Set
4404 *STRICT_OVERFLOW_P to true if the return value is only valid
4405 because signed overflow is undefined; otherwise, do not change
4406 *STRICT_OVERFLOW_P. */
4408 tree
4411 {
4419 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4420 and see if we can refine the range. Some of the cases below may not
4421 happen, but it doesn't seem worth worrying about this. We "continue"
4422 the outer loop when we've changed something; otherwise we "break"
4423 the switch, which will "break" the while. */
4429 {
4435 {
4443 }
4452 }
4454 /* If EXP is a constant, we can evaluate whether this is true or false. */
4456 {
4463 }
4467 }
4468 \f
4469 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4470 type, TYPE, return an expression to test if EXP is in (or out of, depending
4471 on IN_P) the range. Return 0 if the test couldn't be created. */
4473 tree
4476 {
4479 #ifdef HAVE_canonicalize_funcptr_for_compare
4480 /* Disable this optimization for function pointer expressions
4481 on targets that require function pointer canonicalization. */
4486 #endif
4489 {
4495 }
4513 {
4515 {
4519 }
4521 }
4523 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4525 {
4529 {
4531 {
4534 etype
4536 else
4539 }
4542 }
4543 }
4545 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4546 This requires wrap-around arithmetics for the type of the expression.
4547 First make sure that arithmetics in this type is valid, then make sure
4548 that it wraps around. */
4554 {
4557 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4558 for the type in question, as we rely on this here. */
4568 else
4570 }
4580 {
4582 {
4587 }
4589 }
4597 }
4598 \f
4599 /* Return the predecessor of VAL in its type, handling the infinite case. */
4601 static tree
4603 {
4609 else
4612 }
4614 /* Return the successor of VAL in its type, handling the infinite case. */
4616 static tree
4618 {
4624 else
4627 }
4629 /* Given two ranges, see if we can merge them into one. Return 1 if we
4630 can, 0 if we can't. Set the output range into the specified parameters. */
4632 bool
4635 {
4639 tree tem;
4649 /* Make range 0 be the range that starts first, or ends last if they
4650 start at the same value. Swap them if it isn't. */
4653 || (lowequal
4656 {
4660 }
4662 /* Now flag two cases, whether the ranges are disjoint or whether the
4663 second range is totally subsumed in the first. Note that the tests
4664 below are simplified by the ones above. */
4670 /* We now have four cases, depending on whether we are including or
4671 excluding the two ranges. */
4673 {
4674 /* If they don't overlap, the result is false. If the second range
4675 is a subset it is the result. Otherwise, the range is from the start
4676 of the second to the end of the first. */
4681 else
4683 }
4686 {
4687 /* If they don't overlap, the result is the first range. If they are
4688 equal, the result is false. If the second range is a subset of the
4689 first, and the ranges begin at the same place, we go from just after
4690 the end of the second range to the end of the first. If the second
4691 range is not a subset of the first, or if it is a subset and both
4692 ranges end at the same place, the range starts at the start of the
4693 first range and ends just before the second range.
4694 Otherwise, we can't describe this as a single range. */
4700 {
4705 {
4706 /* We are in the weird situation where high0 > high1 but
4707 high1 has no successor. Punt. */
4709 }
4710 }
4712 {
4717 {
4718 /* low0 < low1 but low1 has no predecessor. Punt. */
4720 }
4721 }
4722 else
4724 }
4727 {
4728 /* If they don't overlap, the result is the second range. If the second
4729 is a subset of the first, the result is false. Otherwise,
4730 the range starts just after the first range and ends at the
4731 end of the second. */
4736 else
4737 {
4742 {
4743 /* high1 > high0 but high0 has no successor. Punt. */
4745 }
4746 }
4747 }
4749 else
4750 {
4751 /* The case where we are excluding both ranges. Here the complex case
4752 is if they don't overlap. In that case, the only time we have a
4753 range is if they are adjacent. If the second is a subset of the
4754 first, the result is the first. Otherwise, the range to exclude
4755 starts at the beginning of the first range and ends at the end of the
4756 second. */
4758 {
4763 else
4764 {
4765 /* Canonicalize - [min, x] into - [-, x]. */
4768 {
4773 /* FALLTHROUGH */
4786 }
4788 /* Canonicalize - [x, max] into - [x, -]. */
4791 {
4796 /* FALLTHROUGH */
4812 }
4814 /* The ranges might be also adjacent between the maximum and
4815 minimum values of the given type. For
4816 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4817 return + [x + 1, y - 1]. */
4819 {
4826 }
4827 else
4829 }
4830 }
4833 else
4835 }
4839 }
4840 \f
4842 /* Subroutine of fold, looking inside expressions of the form
4843 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4844 of the COND_EXPR. This function is being used also to optimize
4845 A op B ? C : A, by reversing the comparison first.
4847 Return a folded expression whose code is not a COND_EXPR
4848 anymore, or NULL_TREE if no folding opportunity is found. */
4850 static tree
4853 {
4858 tree tem;
4863 /* If we have A op 0 ? A : -A, consider applying the following
4864 transformations:
4866 A == 0? A : -A same as -A
4867 A != 0? A : -A same as A
4868 A >= 0? A : -A same as abs (A)
4869 A > 0? A : -A same as abs (A)
4870 A <= 0? A : -A same as -abs (A)
4871 A < 0? A : -A same as -abs (A)
4873 None of these transformations work for modes with signed
4874 zeros. If A is +/-0, the first two transformations will
4875 change the sign of the result (from +0 to -0, or vice
4876 versa). The last four will fix the sign of the result,
4877 even though the original expressions could be positive or
4878 negative, depending on the sign of A.
4880 Note that all these transformations are correct if A is
4881 NaN, since the two alternatives (A and -A) are also NaNs. */
4888 /* In the case that A is of the form X-Y, '-A' (arg2) may
4889 have already been folded to Y-X, check for that. */
4897 {
4911 /* Fall through. */
4933 }
4935 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4936 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4937 both transformations are correct when A is NaN: A != 0
4938 is then true, and A == 0 is false. */
4942 {
4947 }
4949 /* Try some transformations of A op B ? A : B.
4951 A == B? A : B same as B
4952 A != B? A : B same as A
4953 A >= B? A : B same as max (A, B)
4954 A > B? A : B same as max (B, A)
4955 A <= B? A : B same as min (A, B)
4956 A < B? A : B same as min (B, A)
4958 As above, these transformations don't work in the presence
4959 of signed zeros. For example, if A and B are zeros of
4960 opposite sign, the first two transformations will change
4961 the sign of the result. In the last four, the original
4962 expressions give different results for (A=+0, B=-0) and
4963 (A=-0, B=+0), but the transformed expressions do not.
4965 The first two transformations are correct if either A or B
4966 is a NaN. In the first transformation, the condition will
4967 be false, and B will indeed be chosen. In the case of the
4968 second transformation, the condition A != B will be true,
4969 and A will be chosen.
4971 The conversions to max() and min() are not correct if B is
4972 a number and A is not. The conditions in the original
4973 expressions will be false, so all four give B. The min()
4974 and max() versions would give a NaN instead. */
4977 /* Avoid these transformations if the COND_EXPR may be used
4978 as an lvalue in the C++ front-end. PR c++/19199. */
4979 && (in_gimple_form
4985 {
4990 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4992 {
4996 }
4999 {
5008 /* In C++ a ?: expression can be an lvalue, so put the
5009 operand which will be used if they are equal first
5010 so that we can convert this back to the
5011 corresponding COND_EXPR. */
5013 {
5022 }
5029 {
5038 }
5053 }
5054 }
5056 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5057 we might still be able to simplify this. For example,
5058 if C1 is one less or one more than C2, this might have started
5059 out as a MIN or MAX and been transformed by this function.
5060 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5066 {
5070 /* We can replace A with C1 in this case. */
5075 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5076 MIN_EXPR, to preserve the signedness of the comparison. */
5078 OEP_ONLY_CONST)
5082 OEP_ONLY_CONST))
5083 {
5086 arg2));
5089 }
5093 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5094 as above. */
5096 OEP_ONLY_CONST)
5100 OEP_ONLY_CONST))
5101 {
5104 arg2));
5107 }
5111 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5112 MAX_EXPR, to preserve the signedness of the comparison. */
5114 OEP_ONLY_CONST)
5118 OEP_ONLY_CONST))
5119 {
5122 arg2));
5124 }
5128 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5130 OEP_ONLY_CONST)
5134 OEP_ONLY_CONST))
5135 {
5138 arg2));
5140 }
5146 }
5149 }
5152 \f
5153 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5154 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5155 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5156 false) >= 2)
5157 #endif
5159 /* EXP is some logical combination of boolean tests. See if we can
5160 merge it into some range test. Return the new tree if so. */
5162 static tree
5165 {
5181 /* If this is an OR operation, invert both sides; we will invert
5182 again at the end. */
5186 /* If both expressions are the same, if we can merge the ranges, and we
5187 can build the range test, return it or it inverted. If one of the
5188 ranges is always true or always false, consider it to be the same
5189 expression as the other. */
5197 {
5201 }
5203 /* On machines where the branch cost is expensive, if this is a
5204 short-circuited branch and the underlying object on both sides
5205 is the same, make a non-short-circuit operation. */
5211 {
5212 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5213 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5214 which cases we can't do this. */
5222 {
5231 {
5234 WARN_STRICT_OVERFLOW_COMPARISON);
5238 }
5239 }
5240 }
5243 }
5244 \f
5245 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5246 bit value. Arrange things so the extra bits will be set to zero if and
5247 only if C is signed-extended to its full width. If MASK is nonzero,
5248 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5250 static tree
5252 {
5255 tree temp;
5260 /* We work by getting just the sign bit into the low-order bit, then
5261 into the high-order bit, then sign-extend. We then XOR that value
5262 with C. */
5265 /* We must use a signed type in order to get an arithmetic right shift.
5266 However, we must also avoid introducing accidental overflows, so that
5267 a subsequent call to integer_zerop will work. Hence we must
5268 do the type conversion here. At this point, the constant is either
5269 zero or one, and the conversion to a signed type can never overflow.
5270 We could get an overflow if this conversion is done anywhere else. */
5279 /* If necessary, convert the type back to match the type of C. */
5284 }
5285 \f
5286 /* For an expression that has the form
5287 (A && B) || ~B
5288 or
5289 (A || B) && ~B,
5290 we can drop one of the inner expressions and simplify to
5291 A || ~B
5292 or
5293 A && ~B
5294 LOC is the location of the resulting expression. OP is the inner
5295 logical operation; the left-hand side in the examples above, while CMPOP
5296 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5297 removing a condition that guards another, as in
5298 (A != NULL && A->...) || A == NULL
5299 which we must not transform. If RHS_ONLY is true, only eliminate the
5300 right-most operand of the inner logical operation. */
5302 static tree
5305 {
5323 {
5326 {
5329 }
5330 }
5332 {
5335 {
5338 }
5339 }
5354 }
5356 /* Find ways of folding logical expressions of LHS and RHS:
5357 Try to merge two comparisons to the same innermost item.
5358 Look for range tests like "ch >= '0' && ch <= '9'".
5359 Look for combinations of simple terms on machines with expensive branches
5360 and evaluate the RHS unconditionally.
5362 For example, if we have p->a == 2 && p->b == 4 and we can make an
5363 object large enough to span both A and B, we can do this with a comparison
5364 against the object ANDed with the a mask.
5366 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5367 operations to do this with one comparison.
5369 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5370 function and the one above.
5372 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5373 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5375 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5376 two operands.
5378 We return the simplified tree or 0 if no optimization is possible. */
5380 static tree
5383 {
5384 /* If this is the "or" of two comparisons, we can do something if
5385 the comparisons are NE_EXPR. If this is the "and", we can do something
5386 if the comparisons are EQ_EXPR. I.e.,
5387 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5389 WANTED_CODE is this operation code. For single bit fields, we can
5390 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5391 comparison for one-bit fields. */
5411 /* Start by getting the comparison codes. Fail if anything is volatile.
5412 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5413 it were surrounded with a NE_EXPR. */
5422 {
5426 }
5429 {
5433 }
5444 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5447 {
5450 {
5455 }
5458 {
5464 }
5465 }
5470 /* If the RHS can be evaluated unconditionally and its operands are
5471 simple, it wins to evaluate the RHS unconditionally on machines
5472 with expensive branches. In this case, this isn't a comparison
5473 that can be merged. */
5480 {
5481 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5492 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5502 }
5504 /* See if the comparisons can be merged. Then get all the parameters for
5505 each side. */
5529 /* It must be true that the inner operation on the lhs of each
5530 comparison must be the same if we are to be able to do anything.
5531 Then see if we have constants. If not, the same must be true for
5532 the rhs's. */
5543 else
5546 /* If either comparison code is not correct for our logical operation,
5547 fail. However, we can convert a one-bit comparison against zero into
5548 the opposite comparison against that bit being set in the field. */
5552 {
5554 {
5555 /* Make the left operand unsigned, since we are only interested
5556 in the value of one bit. Otherwise we are doing the wrong
5557 thing below. */
5560 }
5561 else
5563 }
5565 /* This is analogous to the code for l_const above. */
5567 {
5569 {
5572 }
5573 else
5575 }
5577 /* See if we can find a mode that contains both fields being compared on
5578 the left. If we can't, fail. Otherwise, update all constants and masks
5579 to be relative to a field of that size. */
5584 volatilep);
5594 {
5597 }
5605 {
5612 {
5616 }
5617 }
5619 {
5626 {
5630 }
5631 }
5633 /* If the right sides are not constant, do the same for it. Also,
5634 disallow this optimization if a size or signedness mismatch occurs
5635 between the left and right sides. */
5637 {
5640 /* Make sure the two fields on the right
5641 correspond to the left without being swapped. */
5649 volatilep);
5659 {
5662 }
5671 /* Make a mask that corresponds to both fields being compared.
5672 Do this for both items being compared. If the operands are the
5673 same size and the bits being compared are in the same position
5674 then we can do this by masking both and comparing the masked
5675 results. */
5679 {
5691 }
5693 /* There is still another way we can do something: If both pairs of
5694 fields being compared are adjacent, we may be able to make a wider
5695 field containing them both.
5697 Note that we still must mask the lhs/rhs expressions. Furthermore,
5698 the mask must be shifted to account for the shift done by
5699 make_bit_field_ref. */
5704 {
5705 tree type;
5719 /* Convert to the smaller type before masking out unwanted bits. */
5722 {
5724 {
5728 }
5730 {
5734 }
5735 }
5744 }
5747 }
5749 /* Handle the case of comparisons with constants. If there is something in
5750 common between the masks, those bits of the constants must be the same.
5751 If not, the condition is always false. Test for this to avoid generating
5752 incorrect code below. */
5757 {
5759 {
5762 }
5763 else
5764 {
5767 }
5768 }
5770 /* Construct the expression we will return. First get the component
5771 reference we will make. Unless the mask is all ones the width of
5772 that field, perform the mask operation. Then compare with the
5773 merged constant. */
5783 }
5784 \f
5785 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5786 constant. */
5788 static tree
5791 {
5794 tree comp_const;
5795 tree minmax_const;
5797 tree inner;
5808 /* If something does not permit us to optimize, return the original tree. */
5816 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5817 and GT_EXPR, doing the rest with recursive calls using logical
5818 simplifications. */
5820 {
5822 {
5823 tree tem
5830 }
5833 return
5835 optimize_minmax_comparison
5837 optimize_minmax_comparison
5842 /* MAX (X, 0) == 0 -> X <= 0 */
5846 /* MAX (X, 0) == 5 -> X == 5 */
5850 /* MAX (X, 0) == -1 -> false */
5854 /* MIN (X, 0) == 0 -> X >= 0 */
5858 /* MIN (X, 0) == 5 -> false */
5861 else
5862 /* MIN (X, 0) == -1 -> X == -1 */
5867 /* MAX (X, 0) > 0 -> X > 0
5868 MAX (X, 0) > 5 -> X > 5 */
5872 /* MAX (X, 0) > -1 -> true */
5876 /* MIN (X, 0) > 0 -> false
5877 MIN (X, 0) > 5 -> false */
5880 else
5881 /* MIN (X, 0) > -1 -> X > -1 */
5886 }
5887 }
5888 \f
5889 /* T is an integer expression that is being multiplied, divided, or taken a
5890 modulus (CODE says which and what kind of divide or modulus) by a
5891 constant C. See if we can eliminate that operation by folding it with
5892 other operations already in T. WIDE_TYPE, if non-null, is a type that
5893 should be used for the computation if wider than our type.
5895 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5896 (X * 2) + (Y * 4). We must, however, be assured that either the original
5897 expression would not overflow or that overflow is undefined for the type
5898 in the language in question.
5900 If we return a non-null expression, it is an equivalent form of the
5901 original computation, but need not be in the original type.
5903 We set *STRICT_OVERFLOW_P to true if the return values depends on
5904 signed overflow being undefined. Otherwise we do not change
5905 *STRICT_OVERFLOW_P. */
5907 static tree
5910 {
5911 /* To avoid exponential search depth, refuse to allow recursion past
5912 three levels. Beyond that (1) it's highly unlikely that we'll find
5913 something interesting and (2) we've probably processed it before
5914 when we built the inner expression. */
5917 tree ret;
5922 depth++;
5924 depth--;
5927 }
5929 static tree
5932 {
5943 /* Don't deal with constants of zero here; they confuse the code below. */
5953 /* Note that we need not handle conditional operations here since fold
5954 already handles those cases. So just do arithmetic here. */
5956 {
5958 /* For a constant, we can always simplify if we are a multiply
5959 or (for divide and modulus) if it is a multiple of our constant. */
5967 /* If op0 is an expression ... */
5973 /* ... and has wrapping overflow, and its type is smaller
5974 than ctype, then we cannot pass through as widening. */
5979 /* ... or this is a truncation (t is narrower than op0),
5980 then we cannot pass through this narrowing. */
5983 /* ... or signedness changes for division or modulus,
5984 then we cannot pass through this conversion. */
5988 /* ... or has undefined overflow while the converted to
5989 type has not, we cannot do the operation in the inner type
5990 as that would introduce undefined overflow. */
5996 /* Pass the constant down and see if we can make a simplification. If
5997 we can, replace this expression with the inner simplification for
5998 possible later conversion to our or some other type. */
6003 code == MULT_EXPR
6005 strict_overflow_p))))
6010 /* If widening the type changes it from signed to unsigned, then we
6011 must avoid building ABS_EXPR itself as unsigned. */
6013 {
6017 {
6020 }
6022 }
6023 /* If the constant is negative, we cannot simplify this. */
6026 /* FALLTHROUGH */
6028 /* For division and modulus, type can't be unsigned, as e.g.
6029 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6030 For signed types, even with wrapping overflow, this is fine. */
6039 /* If widening the type changes the signedness, then we can't perform
6040 this optimization as that changes the result. */
6044 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6050 {
6057 }
6061 /* If the second operand is constant, this is a multiplication
6062 or floor division, by a power of two, so we can treat it that
6063 way unless the multiplier or divisor overflows. Signed
6064 left-shift overflow is implementation-defined rather than
6065 undefined in C90, so do not convert signed left shift into
6066 multiplication. */
6069 /* const_binop may not detect overflow correctly,
6070 so check for it explicitly here. */
6074 size_one_node,
6075 op1)))
6079 ctype,
6081 t1),
6086 /* See if we can eliminate the operation on both sides. If we can, we
6087 can return a new PLUS or MINUS. If we can't, the only remaining
6088 cases where we can do anything are if the second operand is a
6089 constant. */
6095 /* If not multiplication, we can only do this if both operands
6096 are divisible by c. */
6099 {
6104 }
6106 /* If this was a subtraction, negate OP1 and set it to be an addition.
6107 This simplifies the logic below. */
6109 {
6111 /* If OP1 was not easily negatable, the constant may be OP0. */
6113 {
6120 }
6121 }
6126 /* If either OP1 or C are negative, this optimization is not safe for
6127 some of the division and remainder types while for others we need
6128 to change the code. */
6130 {
6138 }
6140 /* If it's a multiply or a division/modulus operation of a multiple
6141 of our constant, do the operation and verify it doesn't overflow. */
6144 {
6147 /* We allow the constant to overflow with wrapping semantics. */
6151 }
6152 else
6155 /* If we have an unsigned type, we cannot widen the operation since it
6156 will change the result if the original computation overflowed. */
6160 /* If we were able to eliminate our operation from the first side,
6161 apply our operation to the second side and reform the PLUS. */
6165 /* The last case is if we are a multiply. In that case, we can
6166 apply the distributive law to commute the multiply and addition
6167 if the multiplication of the constants doesn't overflow
6168 and overflow is defined. With undefined overflow
6169 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6175 op1);
6180 /* We have a special case here if we are doing something like
6181 (C * 8) % 4 since we know that's zero. */
6184 /* If the multiplication can overflow we cannot optimize this. */
6188 {
6191 }
6193 /* ... fall through ... */
6197 /* If we can extract our operation from the LHS, do so and return a
6198 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6199 do something only if the second operand is a constant. */
6213 /* If these are the same operation types, we can associate them
6214 assuming no overflow. */
6216 {
6228 }
6230 /* If these operations "cancel" each other, we have the main
6231 optimizations of this pass, which occur when either constant is a
6232 multiple of the other, in which case we replace this with either an
6233 operation or CODE or TCODE.
6235 If we have an unsigned type, we cannot do this since it will change
6236 the result if the original computation overflowed. */
6243 {
6245 {
6252 }
6254 {
6261 }
6262 }
6267 }
6270 }
6271 \f
6272 /* Return a node which has the indicated constant VALUE (either 0 or
6273 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6274 and is of the indicated TYPE. */
6276 tree
6278 {
6287 else
6289 }
6292 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6293 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6294 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6295 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6296 COND is the first argument to CODE; otherwise (as in the example
6297 given here), it is the second argument. TYPE is the type of the
6298 original expression. Return NULL_TREE if no simplification is
6299 possible. */
6301 static tree
6306 {
6316 {
6320 /* If this operand throws an expression, then it does not make
6321 sense to try to perform a logical or arithmetic operation
6322 involving it. */
6327 }
6328 else
6329 {
6334 }
6339 /* This transformation is only worthwhile if we don't have to wrap ARG
6340 in a SAVE_EXPR and the operation can be simplified without recursing
6341 on at least one of the branches once its pushed inside the COND_EXPR. */
6350 {
6354 else
6356 }
6358 {
6362 else
6364 }
6366 /* Check that we have simplified at least one of the branches. */
6371 }
6373 \f
6374 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6376 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6377 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6378 ADDEND is the same as X.
6380 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6381 and finite. The problematic cases are when X is zero, and its mode
6382 has signed zeros. In the case of rounding towards -infinity,
6383 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6384 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6386 bool
6388 {
6392 /* Don't allow the fold with -fsignaling-nans. */
6396 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6400 /* In a vector or complex, we would need to check the sign of all zeros. */
6404 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6408 /* The mode has signed zeros, and we have to honor their sign.
6409 In this situation, there is only one case we can return true for.
6410 X - 0 is the same as X unless rounding towards -infinity is
6411 supported. */
6413 }
6415 /* Subroutine of fold() that checks comparisons of built-in math
6416 functions against real constants.
6418 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6419 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6420 is the type of the result and ARG0 and ARG1 are the operands of the
6421 comparison. ARG1 must be a TREE_REAL_CST.
6423 The function returns the constant folded tree if a simplification
6424 can be made, and NULL_TREE otherwise. */
6426 static tree
6430 {
6431 REAL_VALUE_TYPE c;
6434 {
6440 {
6441 /* sqrt(x) < y is always false, if y is negative. */
6445 /* sqrt(x) > y is always true, if y is negative and we
6446 don't care about NaNs, i.e. negative values of x. */
6450 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6453 }
6455 {
6456 REAL_VALUE_TYPE c2;
6462 {
6463 /* sqrt(x) > y is x == +Inf, when y is very large. */
6468 /* sqrt(x) > y is always false, when y is very large
6469 and we don't care about infinities. */
6471 }
6473 /* sqrt(x) > c is the same as x > c*c. */
6476 }
6478 {
6479 REAL_VALUE_TYPE c2;
6485 {
6486 /* sqrt(x) < y is always true, when y is a very large
6487 value and we don't care about NaNs or Infinities. */
6491 /* sqrt(x) < y is x != +Inf when y is very large and we
6492 don't care about NaNs. */
6497 /* sqrt(x) < y is x >= 0 when y is very large and we
6498 don't care about Infinities. */
6503 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6508 dconst0)),
6511 c2)));
6512 }
6514 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6519 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6524 dconst0)),
6527 c2)));
6528 }
6529 }
6532 }
6534 /* Subroutine of fold() that optimizes comparisons against Infinities,
6535 either +Inf or -Inf.
6537 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6538 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6539 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6541 The function returns the constant folded tree if a simplification
6542 can be made, and NULL_TREE otherwise. */
6544 static tree
6547 {
6548 machine_mode mode;
6549 REAL_VALUE_TYPE max;
6550 tree temp;
6555 /* For negative infinity swap the sense of the comparison. */
6561 {
6563 /* x > +Inf is always false, if with ignore sNANs. */
6569 /* x <= +Inf is always true, if we don't case about NaNs. */
6573 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6579 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6585 /* x < +Inf is always equal to x <= DBL_MAX. */
6591 /* x != +Inf is always equal to !(x > DBL_MAX). */
6603 }
6606 }
6608 /* Subroutine of fold() that optimizes comparisons of a division by
6609 a nonzero integer constant against an integer constant, i.e.
6610 X/C1 op C2.
6612 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6613 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6614 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6616 The function returns the constant folded tree if a simplification
6617 can be made, and NULL_TREE otherwise. */
6619 static tree
6622 {
6630 /* We have to do this the hard way to detect unsigned overflow.
6631 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6637 {
6642 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6646 }
6648 {
6652 {
6671 }
6672 }
6673 else
6674 {
6675 /* A negative divisor reverses the relational operators. */
6681 {
6700 }
6701 }
6704 {
6725 {
6728 }
6733 {
6736 }
6741 {
6744 }
6749 {
6752 }
6757 }
6760 }
6763 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6764 equality/inequality test, then return a simplified form of the test
6765 using a sign testing. Otherwise return NULL. TYPE is the desired
6766 result type. */
6768 static tree
6771 tree result_type)
6772 {
6773 /* If this is testing a single bit, we can optimize the test. */
6777 {
6778 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6779 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6783 /* This is only a win if casting to a signed type is cheap,
6784 i.e. when arg00's type is not a partial mode. */
6787 {
6790 result_type,
6793 }
6794 }
6797 }
6799 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6800 equality/inequality test, then return a simplified form of
6801 the test using shifts and logical operations. Otherwise return
6802 NULL. TYPE is the desired result type. */
6804 tree
6807 {
6808 /* If this is testing a single bit, we can optimize the test. */
6812 {
6821 /* First, see if we can fold the single bit test into a sign-bit
6822 test. */
6824 result_type);
6828 /* Otherwise we have (A & C) != 0 where C is a single bit,
6829 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6830 Similarly for (A & C) == 0. */
6832 /* If INNER is a right shift of a constant and it plus BITNUM does
6833 not overflow, adjust BITNUM and INNER. */
6839 {
6842 }
6844 /* If we are going to be able to omit the AND below, we must do our
6845 operations as unsigned. If we must use the AND, we have a choice.
6846 Normally unsigned is faster, but for some machines signed is. */
6847 #ifdef LOAD_EXTEND_OP
6850 #else
6852 #endif
6868 /* Put the AND last so it can combine with more things. */
6871 /* Make sure to return the proper type. */
6875 }
6877 }
6879 /* Check whether we are allowed to reorder operands arg0 and arg1,
6880 such that the evaluation of arg1 occurs before arg0. */
6882 static bool
6884 {
6891 }
6893 /* Test whether it is preferable two swap two operands, ARG0 and
6894 ARG1, for example because ARG0 is an integer constant and ARG1
6895 isn't. If REORDER is true, only recommend swapping if we can
6896 evaluate the operands in reverse order. */
6898 bool
6900 {
6918 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6919 for commutative and comparison operators. Ensuring a canonical
6920 form allows the optimizers to find additional redundancies without
6921 having to explicitly check for both orderings. */
6927 /* Put SSA_NAMEs last. */
6933 /* Put variables last. */
6940 }
6942 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6943 ARG0 is extended to a wider type. */
6945 static tree
6948 {
6950 tree arg1_unw;
6959 #ifdef HAVE_canonicalize_funcptr_for_compare
6960 /* Disable this optimization if we're casting a function pointer
6961 type on targets that require function pointer canonicalization. */
6966 #endif
6973 /* If possible, express the comparison in the shorter mode. */
6993 /* If we are comparing with the integer that does not fit into the range
6994 of the shorter type, the result is known. */
7005 {
7032 }
7035 }
7037 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7038 ARG0 just the signedness is changed. */
7040 static tree
7043 {
7044 tree arg0_inner;
7054 #ifdef HAVE_canonicalize_funcptr_for_compare
7055 /* Disable this optimization if we're casting a function pointer
7056 type on targets that require function pointer canonicalization. */
7061 #endif
7082 else
7086 }
7089 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7090 means A >= Y && A != MAX, but in this case we know that
7091 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7093 static tree
7095 {
7102 else
7111 {
7114 }
7116 {
7119 }
7120 else
7127 {
7128 /* Convert the pointer types into integer before taking the difference. */
7132 }
7133 else
7140 }
7142 /* Fold a sum or difference of at least one multiplication.
7143 Returns the folded tree or NULL if no simplification could be made. */
7145 static tree
7148 {
7152 /* (A * C) +- (B * C) -> (A+-B) * C.
7153 (A * C) +- A -> A * (C+-1).
7154 We are most concerned about the case where C is a constant,
7155 but other combinations show up during loop reduction. Since
7156 it is not difficult, try all four possibilities. */
7159 {
7162 }
7164 {
7167 }
7168 else
7169 {
7170 /* We cannot generate constant 1 for fract. */
7175 }
7177 {
7180 }
7182 {
7184 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7185 the purpose of this canonicalization. */
7189 {
7192 }
7193 else
7195 }
7196 else
7197 {
7198 /* We cannot generate constant 1 for fract. */
7203 }
7215 /* No identical multiplicands; see if we can find a common
7216 power-of-two factor in non-power-of-two multiplies. This
7217 can help in multi-dimensional array access. */
7220 {
7223 tree maybe_same;
7227 /* Move min of absolute values to int11. */
7229 {
7234 }
7235 else
7239 /* The remainder should not be a constant, otherwise we
7240 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7241 increased the number of multiplications necessary. */
7243 {
7251 }
7252 }
7262 }
7264 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7265 specified by EXPR into the buffer PTR of length LEN bytes.
7266 Return the number of bytes placed in the buffer, or zero
7267 upon failure. */
7269 static int
7271 {
7285 {
7287 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7288 number of bytes. */
7292 {
7299 else
7301 }
7302 else
7307 }
7309 }
7312 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7313 specified by EXPR into the buffer PTR of length LEN bytes.
7314 Return the number of bytes placed in the buffer, or zero
7315 upon failure. */
7317 static int
7319 {
7323 FIXED_VALUE_TYPE value;
7339 }
7342 /* Subroutine of native_encode_expr. Encode the REAL_CST
7343 specified by EXPR into the buffer PTR of length LEN bytes.
7344 Return the number of bytes placed in the buffer, or zero
7345 upon failure. */
7347 static int
7349 {
7355 /* There are always 32 bits in each long, no matter the size of
7356 the hosts long. We handle floating point representations with
7357 up to 192 bits. */
7371 {
7376 {
7383 else
7385 }
7386 else
7392 }
7394 }
7396 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7397 specified by EXPR into the buffer PTR of length LEN bytes.
7398 Return the number of bytes placed in the buffer, or zero
7399 upon failure. */
7401 static int
7403 {
7405 tree part;
7420 }
7423 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7424 specified by EXPR into the buffer PTR of length LEN bytes.
7425 Return the number of bytes placed in the buffer, or zero
7426 upon failure. */
7428 static int
7430 {
7440 {
7442 {
7445 }
7456 }
7458 }
7461 /* Subroutine of native_encode_expr. Encode the STRING_CST
7462 specified by EXPR into the buffer PTR of length LEN bytes.
7463 Return the number of bytes placed in the buffer, or zero
7464 upon failure. */
7466 static int
7468 {
7470 HOST_WIDE_INT total_bytes;
7484 {
7487 {
7490 }
7493 }
7494 else
7497 }
7500 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7501 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7502 buffer PTR of length LEN bytes. If OFF is not -1 then start
7503 the encoding at byte offset OFF and encode at most LEN bytes.
7504 Return the number of bytes placed in the buffer, or zero upon failure. */
7506 int
7508 {
7510 {
7531 }
7532 }
7535 /* Subroutine of native_interpret_expr. Interpret the contents of
7536 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7537 If the buffer cannot be interpreted, return NULL_TREE. */
7539 static tree
7541 {
7551 }
7554 /* Subroutine of native_interpret_expr. Interpret the contents of
7555 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7556 If the buffer cannot be interpreted, return NULL_TREE. */
7558 static tree
7560 {
7562 double_int result;
7563 FIXED_VALUE_TYPE fixed_value;
7573 }
7576 /* Subroutine of native_interpret_expr. Interpret the contents of
7577 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7578 If the buffer cannot be interpreted, return NULL_TREE. */
7580 static tree
7582 {
7587 /* There are always 32 bits in each long, no matter the size of
7588 the hosts long. We handle floating point representations with
7589 up to 192 bits. */
7590 REAL_VALUE_TYPE r;
7601 {
7604 {
7611 else
7613 }
7614 else
7619 }
7623 }
7626 /* Subroutine of native_interpret_expr. Interpret the contents of
7627 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7628 If the buffer cannot be interpreted, return NULL_TREE. */
7630 static tree
7632 {
7647 }
7650 /* Subroutine of native_interpret_expr. Interpret the contents of
7651 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7652 If the buffer cannot be interpreted, return NULL_TREE. */
7654 static tree
7656 {
7669 {
7674 }
7676 }
7679 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7680 the buffer PTR of length LEN as a constant of type TYPE. For
7681 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7682 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7683 return NULL_TREE. */
7685 tree
7687 {
7689 {
7711 }
7712 }
7714 /* Returns true if we can interpret the contents of a native encoding
7715 as TYPE. */
7717 static bool
7719 {
7721 {
7734 }
7735 }
7737 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7738 TYPE at compile-time. If we're unable to perform the conversion
7739 return NULL_TREE. */
7741 static tree
7743 {
7744 /* We support up to 512-bit values (for V8DFmode). */
7748 /* Check that the host and target are sane. */
7757 }
7759 /* Build an expression for the address of T. Folds away INDIRECT_REF
7760 to avoid confusing the gimplify process. */
7762 tree
7764 {
7765 /* The size of the object is not relevant when talking about its address. */
7770 {
7775 }
7785 {
7790 }
7791 else
7795 }
7797 /* Build an expression for the address of T. */
7799 tree
7801 {
7805 }
7807 /* Fold a unary expression of code CODE and type TYPE with operand
7808 OP0. Return the folded expression if folding is successful.
7809 Otherwise, return NULL_TREE. */
7811 tree
7813 {
7814 tree tem;
7815 tree arg0;
7823 {
7826 {
7827 /* Don't use STRIP_NOPS, because signedness of argument type
7828 matters. */
7830 }
7831 else
7832 {
7833 /* Strip any conversions that don't change the mode. This
7834 is safe for every expression, except for a comparison
7835 expression because its signedness is derived from its
7836 operands.
7838 Note that this is done as an internal manipulation within
7839 the constant folder, in order to find the simplest
7840 representation of the arguments so that their form can be
7841 studied. In any cases, the appropriate type conversions
7842 should be put back in the tree that will get out of the
7843 constant folder. */
7845 }
7848 {
7851 {
7855 }
7856 }
7857 }
7864 {
7871 {
7885 /* If this was a conversion, and all we did was to move into
7886 inside the COND_EXPR, bring it back out. But leave it if
7887 it is a conversion from integer to integer and the
7888 result precision is no wider than a word since such a
7889 conversion is cheap and may be optimized away by combine,
7890 while it couldn't if it were outside the COND_EXPR. Then return
7891 so we don't get into an infinite recursion loop taking the
7892 conversion out and then back in. */
7904 && (INTEGRAL_TYPE_P
7917 }
7918 }
7921 {
7927 CASE_CONVERT:
7931 {
7932 /* If we have (type) (a CMP b) and type is an integral type, return
7933 new expression involving the new type. Canonicalize
7934 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7935 non-integral type.
7936 Do not fold the result as that would not simplify further, also
7937 folding again results in recursions. */
7947 }
7949 /* Handle (T *)&A.B.C for A being of type T and B and C
7950 living at offset zero. This occurs frequently in
7951 C++ upcasting and then accessing the base. */
7955 {
7957 tree offset;
7958 machine_mode mode;
7963 /* If the reference was to a (constant) zero offset, we can use
7964 the address of the base if it has the same base type
7965 as the result type and the pointer type is unqualified. */
7972 }
7976 /* Detect assigning a bitfield. */
7978 && DECL_BIT_FIELD
7980 {
7981 /* Don't leave an assignment inside a conversion
7982 unless assigning a bitfield. */
7984 /* First do the assignment, then return converted constant. */
7989 }
7991 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7992 constants (if x has signed type, the sign bit cannot be set
7993 in c). This folds extension into the BIT_AND_EXPR.
7994 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7995 very likely don't have maximal range for their precision and this
7996 transformation effectively doesn't preserve non-maximal ranges. */
8000 {
8011 <= HOST_BITS_PER_WIDE_INT
8013 {
8017 cst &= HOST_WIDE_INT_M1U
8020 #ifdef LOAD_EXTEND_OP
8022 && !flag_syntax_only
8025 {
8029 }
8030 #endif
8031 }
8033 {
8038 }
8039 }
8041 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8042 when one of the new casts will fold away. Conservatively we assume
8043 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8050 {
8054 return fold_build_pointer_plus_loc
8056 }
8058 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8059 of the same precision, and X is an integer type not narrower than
8060 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8066 {
8072 }
8074 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8075 type of X and Y (integer types only). */
8080 {
8081 /* Be careful not to introduce new overflows. */
8082 tree mult_type;
8085 else
8089 {
8096 }
8097 }
8115 /* Convert fabs((double)float) into (double)fabsf(float). */
8118 {
8124 targ0));
8125 }
8126 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8130 /* Strip sign ops from argument. */
8132 {
8137 }
8144 {
8150 }
8156 /* Convert ~ (-A) to A - 1. */
8161 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8167 {
8168 /* Perform the negation in ARG0's type and only then convert
8169 to TYPE as to avoid introducing undefined behavior. */
8174 }
8175 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8194 /* Note that the operand of this must be an int
8195 and its values must be 0 or 1.
8196 ("true" is a fixed value perhaps depending on the language,
8197 but we don't handle values other than 1 correctly yet.) */
8207 {
8215 }
8217 {
8222 }
8224 {
8228 {
8237 }
8238 }
8245 {
8253 }
8255 {
8259 }
8261 {
8265 {
8274 }
8275 }
8279 /* Fold *&X to X if X is an lvalue. */
8281 {
8288 }
8294 }
8297 /* If the operation was a conversion do _not_ mark a resulting constant
8298 with TREE_OVERFLOW if the original constant was not. These conversions
8299 have implementation defined behavior and retaining the TREE_OVERFLOW
8300 flag here would confuse later passes such as VRP. */
8301 tree
8304 {
8313 }
8315 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8316 operands OP0 and OP1. LOC is the location of the resulting expression.
8317 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8318 Return the folded expression if folding is successful. Otherwise,
8319 return NULL_TREE. */
8320 static tree
8323 {
8324 tree tem;
8326 /* We only do these simplifications if we are optimizing. */
8330 /* Check for things like (A || B) && (A || C). We can convert this
8331 to A || (B && C). Note that either operator can be any of the four
8332 truth and/or operations and the transformation will still be
8333 valid. Also note that we only care about order for the
8334 ANDIF and ORIF operators. If B contains side effects, this
8335 might change the truth-value of A. */
8342 {
8362 /* This case if tricky because we must either have commutative
8363 operators or else A10 must not have side-effects. */
8369 a01);
8370 }
8372 /* See if we can build a range comparison. */
8378 {
8382 }
8386 {
8390 }
8392 /* Check for the possibility of merging component references. If our
8393 lhs is another similar operation, try to merge its rhs with our
8394 rhs. Then try to merge our lhs and rhs. */
8408 {
8415 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8416 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8417 We don't want to pack more than two leafs to a non-IF AND/OR
8418 expression.
8419 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8420 equal to IF-CODE, then we don't want to add right-hand operand.
8421 If the inner right-hand side of left-hand operand has
8422 side-effects, or isn't simple, then we can't add to it,
8423 as otherwise we might destroy if-sequence. */
8426 /* Needed for sequence points to handle trappings, and
8427 side-effects. */
8429 {
8431 arg1);
8433 tem);
8434 }
8435 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8436 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8439 /* Needed for sequence points to handle trappings, and
8440 side-effects. */
8442 {
8447 }
8448 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8449 into (A OR B).
8450 For sequence point consistancy, we need to check for trapping,
8451 and side-effects. */
8455 }
8458 }
8460 /* Fold a binary expression of code CODE and type TYPE with operands
8461 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8462 Return the folded expression if folding is successful. Otherwise,
8463 return NULL_TREE. */
8465 static tree
8467 {
8474 else
8477 /* MIN (MAX (a, b), b) == b. */
8482 /* MIN (MAX (b, a), b) == b. */
8488 /* MIN (a, MAX (a, b)) == a. */
8494 /* MIN (a, MAX (b, a)) == a. */
8501 }
8503 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8504 by changing CODE to reduce the magnitude of constants involved in
8505 ARG0 of the comparison.
8506 Returns a canonicalized comparison tree if a simplification was
8507 possible, otherwise returns NULL_TREE.
8508 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8509 valid if signed overflow is undefined. */
8511 static tree
8515 {
8521 /* Match A +- CST code arg1 and CST code arg1. We can change the
8522 first form only if overflow is undefined. */
8525 /* In principle pointers also have undefined overflow behavior,
8526 but that causes problems elsewhere. */
8534 /* Identify the constant in arg0 and its sign. */
8537 else
8541 /* Overflowed constants and zero will cause problems. */
8546 /* See if we can reduce the magnitude of the constant in
8547 arg0 by changing the comparison code. */
8549 {
8550 /* CST <= arg1 -> CST-1 < arg1. */
8553 /* -CST < arg1 -> -CST-1 <= arg1. */
8556 /* CST > arg1 -> CST-1 >= arg1. */
8559 /* -CST >= arg1 -> -CST-1 > arg1. */
8562 else
8564 /* arg1 code' CST' might be more canonical. */
8566 }
8567 else
8568 {
8569 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8573 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8577 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8581 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8585 else
8588 }
8590 /* Now build the constant reduced in magnitude. But not if that
8591 would produce one outside of its types range. */
8599 /* We cannot swap the comparison here as that would cause us to
8600 endlessly recurse. */
8609 /* If swapping might yield to a more canonical form, do so. */
8612 else
8614 }
8616 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8617 overflow further. Try to decrease the magnitude of constants involved
8618 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8619 and put sole constants at the second argument position.
8620 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8622 static tree
8625 {
8626 tree t;
8631 /* Try canonicalization by simplifying arg0. */
8636 {
8640 }
8642 /* Try canonicalization by simplifying arg1 using the swapped
8643 comparison. */
8651 }
8653 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8654 space. This is used to avoid issuing overflow warnings for
8655 expressions like &p->x which can not wrap. */
8657 static bool
8659 {
8666 wide_int wi_offset;
8672 else
8688 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8689 array. */
8691 {
8692 HOST_WIDE_INT base_size;
8697 }
8700 }
8702 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8703 kind INTEGER_CST. This makes sure to properly sign-extend the
8704 constant. */
8706 static HOST_WIDE_INT
8708 {
8714 }
8716 /* Subroutine of fold_binary. This routine performs all of the
8717 transformations that are common to the equality/inequality
8718 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8719 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8720 fold_binary should call fold_binary. Fold a comparison with
8721 tree code CODE and type TYPE with operands OP0 and OP1. Return
8722 the folded comparison or NULL_TREE. */
8724 static tree
8727 {
8737 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8739 && (equality_code
8746 {
8747 const enum tree_code
8754 /* If the constant operation overflowed this can be
8755 simplified as a comparison against INT_MAX/INT_MIN. */
8758 {
8762 /* Get the sign of the constant on the lhs if the
8763 operation were VARIABLE + CONST1. */
8767 /* The sign of the constant determines if we overflowed
8768 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8769 Canonicalize to the INT_MIN overflow by swapping the comparison
8770 if necessary. */
8774 /* We now can look at the canonicalized case
8775 VARIABLE + 1 CODE2 INT_MIN
8776 and decide on the result. */
8778 {
8782 return
8788 return
8793 }
8794 }
8795 else
8796 {
8799 "when changing X +- C1 cmp C2 to "
8801 WARN_STRICT_OVERFLOW_COMPARISON);
8803 }
8804 }
8806 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8808 && equality_code
8810 {
8811 /* ??? The transformation is valid for the other operators if overflow
8812 is undefined for the type, but performing it here badly interacts
8813 with the transformation in fold_cond_expr_with_comparison which
8814 attempts to synthetize ABS_EXPR. */
8818 WARN_STRICT_OVERFLOW_COMPARISON);
8821 }
8823 /* For comparisons of pointers we can decompose it to a compile time
8824 comparison of the base objects and the offsets into the object.
8825 This requires at least one operand being an ADDR_EXPR or a
8826 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8832 {
8835 machine_mode mode;
8839 /* Get base and offset for the access. Strip ADDR_EXPR for
8840 get_inner_reference, but put it back by stripping INDIRECT_REF
8841 off the base object if possible. indirect_baseN will be true
8842 if baseN is not an address but refers to the object itself. */
8845 {
8851 else
8853 }
8855 {
8859 {
8862 }
8865 {
8870 {
8873 }
8874 }
8875 }
8879 {
8885 else
8887 }
8889 {
8893 {
8896 }
8899 {
8904 {
8907 }
8908 }
8909 }
8911 /* A local variable can never be pointed to by
8912 the default SSA name of an incoming parameter. */
8914 && indirect_base0
8917 && !indirect_base1
8922 && indirect_base1
8925 && !indirect_base0
8929 {
8934 }
8935 /* If we have equivalent bases we might be able to simplify. */
8938 {
8939 /* We can fold this expression to a constant if the non-constant
8940 offset parts are equal. */
8949 {
8955 "occur when comparing P +- C1 with "
8957 WARN_STRICT_OVERFLOW_CONDITIONAL);
8960 {
8974 }
8975 }
8976 /* We can simplify the comparison to a comparison of the variable
8977 offset parts if the constant offset parts are equal.
8978 Be careful to use signed sizetype here because otherwise we
8979 mess with array offsets in the wrong way. This is possible
8980 because pointer arithmetic is restricted to retain within an
8981 object and overflow on pointer differences is undefined as of
8982 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8984 && (equality_code
8987 {
8988 /* By converting to signed sizetype we cover middle-end pointer
8989 arithmetic which operates on unsigned pointer types of size
8990 type size and ARRAY_REF offsets which are properly sign or
8991 zero extended from their type in case it is narrower than
8992 sizetype. */
8995 else
8999 else
9006 "occur when comparing P +- C1 with "
9008 WARN_STRICT_OVERFLOW_COMPARISON);
9011 }
9012 }
9013 /* For non-equal bases we can simplify if they are addresses
9014 declarations with different addresses. */
9016 /* We know that !operand_equal_p (base0, base1, 0)
9017 because the if condition was false. But make
9018 sure two decls are not the same. */
9024 /* Watch for aliases. */
9029 {
9036 }
9037 /* For equal offsets we can simplify to a comparison of the
9038 base addresses. */
9040 && (indirect_base0
9042 && (indirect_base1
9047 {
9053 }
9054 }
9056 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9057 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9058 the resulting offset is smaller in absolute value than the
9059 original one and has the same sign. */
9068 {
9073 tree cst;
9075 "occur when combining constants around "
9078 /* Put the constant on the side where it doesn't overflow and is
9079 of lower absolute value and of same sign than before. */
9086 {
9089 variable1,
9093 }
9101 {
9107 variable2);
9108 }
9109 }
9111 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9112 signed arithmetic case. That form is created by the compiler
9113 often enough for folding it to be of value. One example is in
9114 computing loop trip counts after Operator Strength Reduction. */
9121 {
9127 /* Handle unfolded multiplication by zero. */
9132 "eliminating multiplication in comparison "
9134 WARN_STRICT_OVERFLOW_COMPARISON);
9136 /* If const1 is negative we swap the sense of the comparison. */
9141 }
9148 {
9156 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9162 /* (-a) CMP (-b) -> b CMP a */
9169 {
9170 REAL_VALUE_TYPE cst;
9173 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9180 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9181 /* a CMP (-0) -> a CMP 0 */
9186 /* x != NaN is always true, other ops are always false. */
9189 {
9192 }
9194 /* Fold comparisons against infinity. */
9197 {
9201 }
9202 }
9204 /* If this is a comparison of a real constant with a PLUS_EXPR
9205 or a MINUS_EXPR of a real constant, we can convert it into a
9206 comparison with a revised real constant as long as no overflow
9207 occurs when unsafe_math_optimizations are enabled. */
9219 /* Likewise, we can simplify a comparison of a real constant with
9220 a MINUS_EXPR whose first operand is also a real constant, i.e.
9221 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9222 floating-point types only if -fassociative-math is set. */
9228 arg1))
9233 /* Fold comparisons against built-in math functions. */
9235 && flag_unsafe_math_optimizations
9237 {
9241 {
9245 }
9246 }
9247 }
9251 {
9252 /* If we are widening one operand of an integer comparison,
9253 see if the other operand is similarly being widened. Perhaps we
9254 can do the comparison in the narrower type. */
9259 /* Or if we are changing signedness. */
9263 }
9265 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9266 constant, we can simplify it. */
9271 {
9275 }
9277 /* Simplify comparison of something with itself. (For IEEE
9278 floating-point, we can only do some of these simplifications.) */
9280 {
9282 {
9297 /* For NE, we can only do this simplification if integer
9298 or we don't honor IEEE floating point NaNs. */
9302 /* ... fall through ... */
9308 }
9309 }
9311 /* If we are comparing an expression that just has comparisons
9312 of two integer values, arithmetic expressions of those comparisons,
9313 and constants, we can simplify it. There are only three cases
9314 to check: the two values can either be equal, the first can be
9315 greater, or the second can be greater. Fold the expression for
9316 those three values. Since each value must be 0 or 1, we have
9317 eight possibilities, each of which corresponds to the constant 0
9318 or 1 or one of the six possible comparisons.
9320 This handles common cases like (a > b) == 0 but also handles
9321 expressions like ((x > y) - (y > x)) > 0, which supposedly
9322 occur in macroized code. */
9325 {
9330 /* Don't handle degenerate cases here; they should already
9331 have been handled anyway. */
9340 {
9344 /* We can't just pass T to eval_subst in case cval1 or cval2
9345 was the same as ARG1. */
9347 tree high_result
9351 arg1);
9352 tree equal_result
9356 arg1);
9357 tree low_result
9361 arg1);
9363 /* All three of these results should be 0 or 1. Confirm they are.
9364 Then use those values to select the proper code to use. */
9369 {
9370 /* Make a 3-bit mask with the high-order bit being the
9371 value for `>', the next for '=', and the low for '<'. */
9375 {
9377 /* Always false. */
9398 /* Always true. */
9400 }
9403 {
9407 }
9409 }
9410 }
9411 }
9413 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9414 into a single range test. */
9422 {
9426 }
9428 /* Fold ~X op ~Y as Y op X. */
9431 {
9437 }
9439 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9442 {
9448 }
9451 }
9454 /* Subroutine of fold_binary. Optimize complex multiplications of the
9455 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9456 argument EXPR represents the expression "z" of type TYPE. */
9458 static tree
9460 {
9465 {
9468 }
9470 {
9473 }
9474 else
9475 {
9479 }
9488 }
9491 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9492 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9493 guarantees that P and N have the same least significant log2(M) bits.
9494 N is not otherwise constrained. In particular, N is not normalized to
9495 0 <= N < M as is common. In general, the precise value of P is unknown.
9496 M is chosen as large as possible such that constant N can be determined.
9498 Returns M and sets *RESIDUE to N.
9500 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9501 account. This is not always possible due to PR 35705.
9502 */
9504 static unsigned HOST_WIDE_INT
9507 {
9514 {
9519 }
9521 {
9529 allow_func_align);
9535 {
9538 }
9540 {
9543 {
9546 /* Compute the greatest power-of-2 divisor of op1. */
9550 /* If align is non-zero and less than *modulus, replace
9551 *modulus with align., If align is 0, then either op1 is 0
9552 or the greatest power-of-2 divisor of op1 doesn't fit in an
9553 unsigned HOST_WIDE_INT. In either case, no additional
9554 constraint is imposed. */
9559 }
9560 }
9561 }
9563 /* If we get here, we were unable to determine anything useful about the
9564 expression. */
9566 }
9568 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9569 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9571 static bool
9573 {
9577 {
9580 }
9582 {
9588 else
9590 }
9591 else
9597 }
9599 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9600 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9601 NULL_TREE otherwise. */
9603 static tree
9605 {
9622 {
9626 }
9629 {
9635 }
9636 else
9638 }
9640 /* Try to fold a pointer difference of type TYPE two address expressions of
9641 array references AREF0 and AREF1 using location LOC. Return a
9642 simplified expression for the difference or NULL_TREE. */
9644 static tree
9647 {
9652 /* If the bases are array references as well, recurse. If the bases
9653 are pointer indirections compute the difference of the pointers.
9654 If the bases are equal, we are set. */
9657 && (base_offset
9665 {
9671 base_offset,
9674 }
9676 }
9678 /* If the real or vector real constant CST of type TYPE has an exact
9679 inverse, return it, else return NULL. */
9681 tree
9683 {
9684 REAL_VALUE_TYPE r;
9686 machine_mode mode;
9690 {
9706 {
9711 }
9717 }
9718 }
9720 /* Mask out the tz least significant bits of X of type TYPE where
9721 tz is the number of trailing zeroes in Y. */
9722 static wide_int
9724 {
9729 }
9731 /* Return true when T is an address and is known to be nonzero.
9732 For floating point we further ensure that T is not denormal.
9733 Similar logic is present in nonzero_address in rtlanal.h.
9735 If the return value is based on the assumption that signed overflow
9736 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9737 change *STRICT_OVERFLOW_P. */
9739 static bool
9741 {
9745 /* Doing something useful for floating point would need more work. */
9751 {
9754 strict_overflow_p);
9760 strict_overflow_p);
9768 }
9771 {
9774 strict_overflow_p);
9782 strict_overflow_p);
9797 strict_overflow_p);
9801 strict_overflow_p);
9804 {
9816 }
9820 }
9822 }
9824 /* Return true when T is an address and is known to be nonzero.
9825 Handle warnings about undefined signed overflow. */
9827 static bool
9829 {
9836 "determining that expression is always "
9838 WARN_STRICT_OVERFLOW_MISC);
9840 }
9842 /* Fold a binary expression of code CODE and type TYPE with operands
9843 OP0 and OP1. LOC is the location of the resulting expression.
9844 Return the folded expression if folding is successful. Otherwise,
9845 return NULL_TREE. */
9847 tree
9850 {
9865 /* Strip any conversions that don't change the mode. This is
9866 safe for every expression, except for a comparison expression
9867 because its signedness is derived from its operands. So, in
9868 the latter case, only strip conversions that don't change the
9869 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9870 preserved.
9872 Note that this is done as an internal manipulation within the
9873 constant folder, in order to find the simplest representation
9874 of the arguments so that their form can be studied. In any
9875 cases, the appropriate type conversions should be put back in
9876 the tree that will get out of the constant folder. */
9879 {
9882 }
9883 else
9884 {
9887 }
9889 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9890 constant but we can't do arithmetic on them. */
9892 {
9895 {
9899 }
9900 }
9902 /* If this is a commutative operation, and ARG0 is a constant, move it
9903 to ARG1 to reduce the number of tests below. */
9908 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9909 to ARG1 to reduce the number of tests below. */
9918 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9920 First check for cases where an arithmetic operation is applied to a
9921 compound, conditional, or comparison operation. Push the arithmetic
9922 operation inside the compound or conditional to see if any folding
9923 can then be done. Convert comparison to conditional for this purpose.
9924 The also optimizes non-constant cases that used to be done in
9925 expand_expr.
9927 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9928 one of the operands is a comparison and the other is a comparison, a
9929 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9930 code below would make the expression more complex. Change it to a
9931 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9932 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9945 {
9949 boolean_type_node,
9957 }
9961 {
9963 {
9968 tem);
9969 }
9972 {
9977 tem);
9978 }
9983 {
9989 }
9994 {
10000 }
10001 }
10004 {
10006 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10009 {
10015 }
10017 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10020 {
10021 tree base;
10022 HOST_WIDE_INT coffset;
10031 }
10036 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10042 arg1),
10044 arg0)));
10050 {
10051 /* X + (X / CST) * -CST is X % CST. */
10056 {
10065 cst0));
10066 }
10067 }
10069 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10070 one. Make sure the type is not saturating and has the signedness of
10071 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10072 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10079 {
10083 }
10086 {
10087 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10088 with a constant, and the two constants have no bits in common,
10089 we should treat this as a BIT_IOR_EXPR since this may produce more
10090 simplifications. */
10097 {
10100 }
10102 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10103 (plus (plus (mult) (mult)) (foo)) so that we can
10104 take advantage of the factoring cases below. */
10113 {
10119 else
10132 parg0),
10134 marg)),
10138 return
10144 parg1)));
10145 }
10146 }
10147 else
10148 {
10149 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10150 to __complex__ ( x, y ). This is not the same for SNaNs or
10151 if signed zeros are involved. */
10155 {
10162 {
10166 {
10172 }
10174 {
10180 }
10181 }
10182 }
10190 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10191 We associate floats only if the user has specified
10192 -fassociative-math. */
10196 {
10201 {
10202 tree tree0;
10205 }
10206 }
10207 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10208 We associate floats only if the user has specified
10209 -fassociative-math. */
10213 {
10218 {
10219 tree tree0;
10222 }
10223 }
10224 }
10226 bit_rotate:
10227 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10228 is a rotate of A by C1 bits. */
10229 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10230 is a rotate of A by B bits. */
10231 {
10233 tree rtype;
10242 /* Only create rotates in complete modes. Other cases are not
10243 expanded properly. */
10246 {
10260 {
10264 code0 == LSHIFT_EXPR
10268 }
10270 {
10278 element_precision
10282 return
10285 ? LROTATE_EXPR
10290 }
10292 {
10300 element_precision
10304 return fold_convert_loc
10307 ? LROTATE_EXPR
10311 }
10312 }
10313 }
10315 associate:
10316 /* In most languages, can't associate operations on floats through
10317 parentheses. Rather than remember where the parentheses were, we
10318 don't associate floats at all, unless the user has specified
10319 -fassociative-math.
10320 And, we need to make sure type is not saturating. */
10324 {
10330 /* Split both trees into variables, constants, and literals. Then
10331 associate each group together, the constants with literals,
10332 then the result with variables. This increases the chances of
10333 literals being recombined later and of generating relocatable
10334 expressions for the sum of a constant and literal. */
10339 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10343 /* With undefined overflow prefer doing association in a type
10344 which wraps on overflow, if that is one of the operand types. */
10347 {
10355 }
10357 /* With undefined overflow we can only associate constants with one
10358 variable, and constants whose association doesn't overflow. */
10361 {
10363 {
10381 /* The only case we can still associate with two variables
10382 is if they are the same, modulo negation and bit-pattern
10383 preserving conversions. */
10386 }
10387 }
10389 /* Only do something if we found more than two objects. Otherwise,
10390 nothing has changed and we risk infinite recursion. */
10396 {
10408 /* Preserve the MINUS_EXPR if the negative part of the literal is
10409 greater than the positive part. Otherwise, the multiplicative
10410 folding code (i.e extract_muldiv) may be fooled in case
10411 unsigned constants are subtracted, like in the following
10412 example: ((X*2 + 4) - 8U)/2. */
10414 {
10418 {
10422 }
10423 else
10424 {
10428 }
10429 }
10431 /* Don't introduce overflows through reassociation. */
10438 {
10440 return
10444 else
10445 {
10448 return
10452 }
10453 }
10456 return
10459 }
10460 }
10465 /* Pointer simplifications for subtraction, simple reassociations. */
10467 {
10468 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10471 {
10481 }
10482 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10484 {
10491 }
10492 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10493 simplifies. */
10495 {
10502 arg10);
10505 }
10506 }
10507 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10517 /* X - (X / Y) * Y is X % Y. */
10525 return
10531 {
10532 /* Fold A - (A & B) into ~B & A. */
10535 {
10537 {
10544 }
10546 {
10553 }
10554 }
10556 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10557 any power of 2 minus 1. */
10562 {
10568 {
10572 }
10573 }
10574 }
10576 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10577 __complex__ ( x, -y ). This is not the same for SNaNs or if
10578 signed zeros are involved. */
10582 {
10589 {
10593 {
10595 arg1r ? arg1r
10600 }
10602 {
10606 arg1i ? arg1i
10609 }
10610 }
10611 }
10613 /* A - B -> A + (-B) if B is easily negatable. */
10617 /* Avoid this transformation if B is a positive REAL_CST. */
10626 /* Try folding difference of addresses. */
10627 {
10628 HOST_WIDE_INT diff;
10634 }
10636 /* Fold &a[i] - &a[j] to i-j. */
10641 {
10647 }
10650 && flag_unsafe_math_optimizations
10656 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10657 one. Make sure the type is not saturating and has the signedness of
10658 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10659 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10666 {
10670 }
10675 /* (-A) * (-B) -> A * B */
10690 {
10691 /* Transform x * -C into -x * C if x is easily negatable. */
10700 tem);
10702 /* (a * (1 << b)) is (a << b) */
10712 /* (A + A) * C -> A * 2 * C */
10724 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10725 sign-changing only. */
10735 {
10738 "occur when simplifying "
10740 WARN_STRICT_OVERFLOW_MISC);
10742 }
10744 /* Optimize z * conj(z) for integer complex numbers. */
10751 }
10752 else
10753 {
10754 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10755 the result for floating point types due to rounding so it is applied
10756 only if -fassociative-math was specify. */
10761 {
10763 arg1);
10767 }
10769 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10771 {
10774 {
10777 }
10778 }
10780 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10781 This is not the same for NaNs or if signed zeros are
10782 involved. */
10788 {
10791 return
10797 return
10802 }
10804 /* Optimize z * conj(z) for floating point complex numbers.
10805 Guarded by flag_unsafe_math_optimizations as non-finite
10806 imaginary components don't produce scalar results. */
10817 {
10821 /* Optimizations of root(...)*root(...). */
10823 {
10828 /* Optimize sqrt(x)*sqrt(x) as x. */
10834 /* Optimize root(x)*root(y) as root(x*y). */
10838 }
10840 /* Optimize expN(x)*expN(y) as expN(x+y). */
10842 {
10848 }
10850 /* Optimizations of pow(...)*pow(...). */
10854 {
10860 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10862 {
10867 }
10869 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10871 {
10876 }
10877 }
10879 /* Optimize tan(x)*cos(x) as sin(x). */
10888 {
10894 }
10896 /* Optimize x*pow(x,c) as pow(x,c+1). */
10900 {
10906 {
10908 REAL_VALUE_TYPE c;
10909 tree arg;
10915 }
10916 }
10918 /* Optimize pow(x,c)*x as pow(x,c+1). */
10922 {
10928 {
10930 REAL_VALUE_TYPE c;
10931 tree arg;
10937 }
10938 }
10940 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10942 && optimize
10944 {
10948 {
10951 }
10952 }
10953 }
10954 }
10958 bit_ior:
10959 /* ~X | X is -1. */
10962 {
10966 }
10968 /* X | ~X is -1. */
10971 {
10975 }
10977 /* Canonicalize (X & C1) | C2. */
10981 {
10986 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10994 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10999 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11000 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11001 mode which allows further optimizations. */
11006 {
11010 {
11013 }
11014 }
11021 c3)),
11022 arg1);
11023 }
11025 /* (X & ~Y) | (~X & Y) is X ^ Y */
11028 {
11045 }
11051 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11053 This results in more efficient code for machines without a NAND
11054 instruction. Combine will canonicalize to the first form
11055 which will allow use of NAND instructions provided by the
11056 backend if they exist. */
11059 {
11060 return
11067 }
11069 /* See if this can be simplified into a rotate first. If that
11070 is unsuccessful continue in the association code. */
11074 /* ~X ^ X is -1. */
11077 {
11081 }
11083 /* X ^ ~X is -1. */
11086 {
11090 }
11092 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11093 with a constant, and the two constants have no bits in common,
11094 we should treat this as a BIT_IOR_EXPR since this may produce more
11095 simplifications. */
11102 {
11105 }
11107 /* (X | Y) ^ X -> Y & ~ X*/
11110 {
11113 arg1);
11118 }
11120 /* (Y | X) ^ X -> Y & ~ X*/
11123 {
11126 arg1);
11131 }
11133 /* X ^ (X | Y) -> Y & ~ X*/
11136 {
11139 arg0);
11144 }
11146 /* X ^ (Y | X) -> Y & ~ X*/
11149 {
11152 arg0);
11157 }
11159 /* Convert ~X ^ ~Y to X ^ Y. */
11168 /* Convert ~X ^ C to X ^ ~C. */
11176 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11184 /* Fold (X & Y) ^ Y as ~X & Y. */
11187 {
11192 }
11193 /* Fold (X & Y) ^ X as ~Y & X. */
11197 {
11202 }
11203 /* Fold X ^ (X & Y) as X & ~Y. */
11206 {
11211 }
11212 /* Fold X ^ (Y & X) as ~Y & X. */
11216 {
11221 }
11223 /* See if this can be simplified into a rotate first. If that
11224 is unsuccessful continue in the association code. */
11228 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11236 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11244 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11249 {
11250 tree tem2;
11257 }
11258 /* Fold ~X & 1 as (X & 1) == 0. */
11262 {
11263 tree tem2;
11270 }
11271 /* Fold !X & 1 as X == 0. */
11274 {
11278 }
11280 /* Fold (X ^ Y) & Y as ~X & Y. */
11283 {
11288 }
11289 /* Fold (X ^ Y) & X as ~Y & X. */
11293 {
11298 }
11299 /* Fold X & (X ^ Y) as X & ~Y. */
11302 {
11307 }
11308 /* Fold X & (Y ^ X) as ~Y & X. */
11312 {
11317 }
11319 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11320 multiple of 1 << CST. */
11322 {
11329 }
11331 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11332 bits from CST2. */
11336 {
11344 {
11345 /* Avoid the transform if arg1 is a mask of some
11346 mode which allows further optimizations. */
11353 }
11354 }
11356 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11357 ((A & N) + B) & M -> (A + B) & M
11358 Similarly if (N & M) == 0,
11359 ((A | N) + B) & M -> (A + B) & M
11360 and for - instead of + (or unary - instead of +)
11361 and/or ^ instead of |.
11362 If B is constant and (B & M) == 0, fold into A & M. */
11364 {
11373 {
11376 wide_int cst0;
11378 /* Now we know that arg0 is (C + D) or (C - D) or
11379 -C and arg1 (M) is == (1LL << cst) - 1.
11380 Store C into PMOP[0] and D into PMOP[1]. */
11384 {
11387 }
11394 {
11404 {
11407 }
11410 /* If C or D is of the form (A & N) where
11411 (N & M) == M, or of the form (A | N) or
11412 (A ^ N) where (N & M) == 0, replace it with A. */
11416 /* If C or D is a N where (N & M) == 0, it can be
11417 omitted (assumed 0). */
11425 }
11427 /* Only build anything new if we optimized one or both arguments
11428 above. */
11432 {
11435 {
11436 /* Perform the operations in a type that has defined
11437 overflow behavior. */
11443 }
11448 {
11456 else
11458 }
11461 else
11464 /* TEM is now the new binary +, - or unary - replacement. */
11468 }
11469 }
11470 }
11475 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11478 {
11483 return
11485 }
11487 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11489 This results in more efficient code for machines without a NOR
11490 instruction. Combine will canonicalize to the first form
11491 which will allow use of NOR instructions provided by the
11492 backend if they exist. */
11495 {
11502 }
11504 /* If arg0 is derived from the address of an object or function, we may
11505 be able to fold this expression using the object or function's
11506 alignment. */
11508 {
11515 /* This works because modulus is a power of 2. If this weren't the
11516 case, we'd have to replace it by its greatest power-of-2
11517 divisor: modulus & -modulus. */
11520 }
11522 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11523 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11524 if the new mask might be further optimized. */
11533 {
11544 {
11547 /* See if more bits can be proven as zero because of
11548 zero extension. */
11551 {
11556 {
11558 /* See if we can shorten the right shift. */
11561 /* Otherwise X >> C1 is all zeros, so we'll optimize
11562 it into (X, 0) later on by making sure zerobits
11563 is all ones. */
11564 }
11565 }
11568 {
11571 }
11572 /* For arithmetic shift if sign bit could be set, zerobits
11573 can contain actually sign bits, so no transformation is
11574 possible, unless MASK masks them all away. In that
11575 case the shift needs to be converted into logical shift. */
11578 {
11581 else
11583 }
11584 }
11586 /* ((X << 16) & 0xff00) is (X, 0). */
11593 {
11594 /* Only do the transformation if NEWMASK is some integer
11595 mode's mask. */
11602 {
11603 tree newmaskt;
11606 {
11612 }
11613 else
11618 }
11619 }
11620 }
11625 /* Don't touch a floating-point divide by zero unless the mode
11626 of the constant can represent infinity. */
11632 /* (-A) / (-B) -> A / B */
11642 /* Convert A/B/C to A/(B*C). */
11649 /* Convert A/(B/C) to (A/B)*C. */
11657 /* Convert C1/(X*C2) into (C1/C2)/X. */
11662 {
11668 }
11671 {
11675 /* Optimize sin(x)/cos(x) as tan(x). */
11681 {
11686 }
11688 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11694 {
11698 {
11703 }
11704 }
11706 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11707 NaNs or Infinities. */
11711 {
11718 {
11723 }
11724 }
11726 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11727 NaNs or Infinities. */
11731 {
11738 {
11742 {
11746 tmp);
11747 }
11748 }
11749 }
11751 /* Optimize pow(x,c)/x as pow(x,c-1). */
11755 {
11761 {
11763 REAL_VALUE_TYPE c;
11764 tree arg;
11770 }
11771 }
11773 /* Optimize a/root(b/c) into a*root(c/b). */
11775 {
11779 {
11788 }
11789 }
11791 /* Optimize x/expN(y) into x*expN(-y). */
11793 {
11800 }
11802 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11806 {
11814 }
11815 }
11819 /* Optimize (X & (-A)) / A where A is a power of 2,
11820 to X >> log2(A) */
11824 {
11832 }
11833 }
11835 /* Fall through */
11838 /* Simplify A / (B << N) where A and B are positive and B is
11839 a power of 2, to A >> (N + log2(B)). */
11844 {
11847 {
11855 WARN_STRICT_OVERFLOW_MISC);
11861 }
11862 }
11864 /* Fall through */
11872 /* Convert -A / -B to A / B when the type is signed and overflow is
11873 undefined. */
11877 {
11880 "when distributing negation across "
11882 WARN_STRICT_OVERFLOW_MISC);
11888 }
11892 {
11895 "when distributing negation across "
11897 WARN_STRICT_OVERFLOW_MISC);
11903 }
11905 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11906 operation, EXACT_DIV_EXPR.
11908 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11909 At one time others generated faster code, it's not clear if they do
11910 after the last round to changes to the DIV code in expmed.c. */
11919 {
11923 WARN_STRICT_OVERFLOW_MISC);
11925 }
11933 /* X % -Y is the same as X % Y. */
11946 {
11950 WARN_STRICT_OVERFLOW_MISC);
11952 }
11954 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11955 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11959 {
11961 /* Also optimize A % (C << N) where C is a power of 2,
11962 to A & ((C << N) - 1). */
11967 {
11968 tree mask
11973 "occur when simplifying "
11975 WARN_STRICT_OVERFLOW_MISC);
11979 }
11980 }
11988 /* Since negative shift count is not well-defined,
11989 don't try to compute it in the compiler. */
11995 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12000 {
12004 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12005 being well defined. */
12007 {
12013 else
12015 }
12019 }
12021 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12022 into x & ((unsigned)-1 >> c) for unsigned types. */
12030 {
12033 tree lshift;
12034 tree arg00;
12037 {
12044 }
12045 }
12047 /* If we have a rotate of a bit operation with the rotate count and
12048 the second operand of the bit operation both constant,
12049 permute the two operations. */
12061 /* Two consecutive rotates adding up to the some integer
12062 multiple of the precision of the type can be ignored. */
12070 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12071 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12072 if the latter can be further optimized. */
12077 {
12081 arg1);
12085 arg1);
12089 }
12106 /* Note that the operands of this must be ints
12107 and their values must be 0 or 1.
12108 ("true" is a fixed value perhaps depending on the language.) */
12109 /* If first arg is constant zero, return it. */
12113 /* If either arg is constant true, drop it. */
12117 /* Preserve sequence points. */
12120 /* If second arg is constant zero, result is zero, but first arg
12121 must be evaluated. */
12124 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12125 case will be handled here. */
12129 /* !X && X is always false. */
12133 /* X && !X is always false. */
12138 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12139 means A >= Y && A != MAX, but in this case we know that
12140 A < X <= MAX. */
12144 {
12152 }
12161 /* Note that the operands of this must be ints
12162 and their values must be 0 or true.
12163 ("true" is a fixed value perhaps depending on the language.) */
12164 /* If first arg is constant true, return it. */
12168 /* If either arg is constant zero, drop it. */
12172 /* Preserve sequence points. */
12175 /* If second arg is constant true, result is true, but we must
12176 evaluate first arg. */
12179 /* Likewise for first arg, but note this only occurs here for
12180 TRUTH_OR_EXPR. */
12184 /* !X || X is always true. */
12188 /* X || !X is always true. */
12193 /* (X && !Y) || (!X && Y) is X ^ Y */
12196 {
12213 }
12222 /* If the second arg is constant zero, drop it. */
12225 /* If the second arg is constant true, this is a logical inversion. */
12227 {
12230 }
12231 /* Identical arguments cancel to zero. */
12235 /* !X ^ X is always true. */
12240 /* X ^ !X is always true. */
12256 /* bool_var != 0 becomes bool_var. */
12261 /* bool_var == 1 becomes bool_var. */
12266 /* bool_var != 1 becomes !bool_var. */
12273 /* bool_var == 0 becomes !bool_var. */
12280 /* !exp != 0 becomes !exp */
12285 /* If this is an equality comparison of the address of two non-weak,
12286 unaliased symbols neither of which are extern (since we do not
12287 have access to attributes for externs), then we know the result. */
12292 {
12300 else
12305 type);
12306 }
12308 /* Similarly for a NEGATE_EXPR. */
12312 arg1)))
12317 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12325 arg1),
12328 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12337 {
12341 val,
12345 }
12347 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12354 {
12356 code == NE_EXPR
12359 }
12361 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12366 /* If this is an EQ or NE comparison with zero and ARG0 is
12367 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12368 two operations, but the latter can be done in one less insn
12369 on machines that have only two-operand insns or on which a
12370 constant cannot be the first operand. */
12373 {
12378 {
12385 arg1);
12386 }
12389 {
12396 arg1);
12397 }
12398 }
12400 /* If this is an NE or EQ comparison of zero against the result of a
12401 signed MOD operation whose second operand is a power of 2, make
12402 the MOD operation unsigned since it is simpler and equivalent. */
12410 {
12420 }
12422 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12423 C1 is a valid shift constant, and C2 is a power of two, i.e.
12424 a single bit. */
12428 == INTEGER_CST
12431 {
12436 /* Check for a valid shift count. */
12438 {
12442 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12443 can be rewritten as (X & (C2 << C1)) != 0. */
12445 {
12450 }
12451 /* Otherwise, for signed (arithmetic) shifts,
12452 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12453 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12457 /* Otherwise, of unsigned (logical) shifts,
12458 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12459 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12460 else
12464 arg000);
12465 }
12466 }
12468 /* If we have (A & C) == C where C is a power of 2, convert this into
12469 (A & C) != 0. Similarly for NE_EXPR. */
12475 integer_zero_node));
12477 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12478 bit, then fold the expression into A < 0 or A >= 0. */
12483 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12484 Similarly for NE_EXPR. */
12488 {
12492 tree dandnotc
12495 notc);
12499 }
12501 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12502 Similarly for NE_EXPR. */
12506 {
12508 tree candnotd
12515 }
12517 /* If this is a comparison of a field, we may be able to simplify it. */
12520 /* Handle the constant case even without -O
12521 to make sure the warnings are given. */
12523 {
12527 }
12529 /* Optimize comparisons of strlen vs zero to a compare of the
12530 first character of the string vs zero. To wit,
12531 strlen(ptr) == 0 => *ptr == 0
12532 strlen(ptr) != 0 => *ptr != 0
12533 Other cases should reduce to one of these two (or a constant)
12534 due to the return value of strlen being unsigned. */
12537 {
12545 {
12550 }
12551 }
12553 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12554 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12558 {
12563 {
12565 {
12568 }
12571 }
12572 }
12574 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12580 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12585 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12592 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12600 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12601 (X & C) == 0 when C is a single bit. */
12606 {
12613 arg1));
12614 }
12616 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12617 constant C is a power of two, i.e. a single bit. */
12624 {
12628 }
12630 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12631 when is C is a power of two, i.e. a single bit. */
12638 {
12644 }
12648 {
12651 }
12653 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12661 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12664 {
12677 arg01),
12686 arg01),
12695 arg00),
12704 arg00),
12706 }
12710 {
12717 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12718 operand_equal_p guarantees no side-effects so we don't need
12719 to use omit_one_operand on Z. */
12723 arg10));
12727 arg11));
12731 arg10));
12735 arg11));
12737 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12740 {
12746 }
12747 }
12749 /* Attempt to simplify equality/inequality comparisons of complex
12750 values. Only lower the comparison if the result is known or
12751 can be simplified to a single scalar comparison. */
12756 {
12761 {
12764 }
12765 else
12766 {
12769 }
12772 {
12775 }
12776 else
12777 {
12780 }
12784 {
12786 {
12791 }
12792 else
12793 {
12798 }
12799 }
12803 {
12805 {
12810 }
12811 else
12812 {
12817 }
12818 }
12819 }
12831 /* Transform comparisons of the form X +- C CMP X. */
12838 {
12845 else
12848 /* (X - c) > X becomes false. */
12852 {
12856 "occur when assuming that (X - c) > X "
12858 WARN_STRICT_OVERFLOW_ALL);
12860 }
12862 /* Likewise (X + c) < X becomes false. */
12866 {
12870 "occur when assuming that "
12872 WARN_STRICT_OVERFLOW_ALL);
12874 }
12876 /* Convert (X - c) <= X to true. */
12881 {
12885 "occur when assuming that "
12887 WARN_STRICT_OVERFLOW_ALL);
12889 }
12891 /* Convert (X + c) >= X to true. */
12896 {
12900 "occur when assuming that "
12902 WARN_STRICT_OVERFLOW_ALL);
12904 }
12907 {
12908 /* Convert X + c > X and X - c < X to true for integers. */
12912 {
12915 "not occur when assuming that "
12917 WARN_STRICT_OVERFLOW_ALL);
12919 }
12924 {
12927 "not occur when assuming that "
12929 WARN_STRICT_OVERFLOW_ALL);
12931 }
12933 /* Convert X + c <= X and X - c >= X to false for integers. */
12937 {
12940 "not occur when assuming that "
12942 WARN_STRICT_OVERFLOW_ALL);
12944 }
12949 {
12952 "not occur when assuming that "
12954 WARN_STRICT_OVERFLOW_ALL);
12956 }
12957 }
12958 }
12960 /* Comparisons with the highest or lowest possible integer of
12961 the specified precision will have known values. */
12962 {
12968 {
12975 {
12988 /* The GE_EXPR and LT_EXPR cases above are not normally
12989 reached because of previous transformations. */
12993 }
12996 {
13003 arg1);
13009 arg0),
13010 arg1);
13013 }
13016 {
13031 }
13034 {
13041 arg1);
13047 arg0),
13048 arg1);
13051 }
13055 /* We will flip the signedness of the comparison operator
13056 associated with the mode of arg1, so the sign bit is
13057 specified by this mode. Check that arg1 is the signed
13058 max associated with this sign bit. */
13060 /* signed_type does not work on pointer types. */
13062 {
13063 /* The following case also applies to X < signed_max+1
13064 and X >= signed_max+1 because previous transformations. */
13066 {
13072 }
13073 }
13074 }
13075 }
13077 /* If we are comparing an ABS_EXPR with a constant, we can
13078 convert all the cases into explicit comparisons, but they may
13079 well not be faster than doing the ABS and one comparison.
13080 But ABS (X) <= C is a range comparison, which becomes a subtraction
13081 and a comparison, and is probably faster. */
13095 /* Convert ABS_EXPR<x> >= 0 to true. */
13102 {
13105 "when simplifying comparison of "
13107 WARN_STRICT_OVERFLOW_CONDITIONAL);
13110 arg0);
13111 }
13113 /* Convert ABS_EXPR<x> < 0 to false. */
13118 {
13121 "when simplifying comparison of "
13123 WARN_STRICT_OVERFLOW_CONDITIONAL);
13126 arg0);
13127 }
13129 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13130 and similarly for >= into !=. */
13140 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13141 otherwise Y might be >= # of bits in X's type and thus e.g.
13142 (unsigned char) (1 << Y) for Y 15 might be 0.
13143 If the cast is widening, then 1 << Y should have unsigned type,
13144 otherwise if Y is number of bits in the signed shift type minus 1,
13145 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13146 31 might be 0xffffffff80000000. */
13157 {
13163 }
13176 {
13180 }
13182 /* If the first operand is NaN, the result is constant. */
13186 {
13188 ? integer_zero_node
13191 }
13193 /* If the second operand is NaN, the result is constant. */
13197 {
13199 ? integer_zero_node
13202 }
13204 /* Simplify unordered comparison of something with itself. */
13210 && !flag_trapping_math
13214 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13215 {
13227 }
13232 /* When pedantic, a compound expression can be neither an lvalue
13233 nor an integer constant expression. */
13236 /* Don't let (0, 0) be null pointer constant. */
13242 /* An ASSERT_EXPR should never be passed to fold_binary. */
13248 }
13250 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13251 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13252 of GOTO_EXPR. */
13254 static tree
13256 {
13258 {
13265 /* ... fall through ... */
13269 }
13270 }
13272 /* Return whether the sub-tree ST contains a label which is accessible from
13273 outside the sub-tree. */
13275 static bool
13277 {
13278 return
13280 }
13282 /* Fold a ternary expression of code CODE and type TYPE with operands
13283 OP0, OP1, and OP2. Return the folded expression if folding is
13284 successful. Otherwise, return NULL_TREE. */
13286 tree
13289 {
13290 tree tem;
13297 /* If this is a commutative operation, and OP0 is a constant, move it
13298 to OP1 to reduce the number of tests below. */
13307 /* Strip any conversions that don't change the mode. This is safe
13308 for every expression, except for a comparison expression because
13309 its signedness is derived from its operands. So, in the latter
13310 case, only strip conversions that don't change the signedness.
13312 Note that this is done as an internal manipulation within the
13313 constant folder, in order to find the simplest representation of
13314 the arguments so that their form can be studied. In any cases,
13315 the appropriate type conversions should be put back in the tree
13316 that will get out of the constant folder. */
13318 {
13321 }
13324 {
13327 }
13330 {
13333 }
13336 {
13340 {
13346 }
13351 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13352 so all simple results must be passed through pedantic_non_lvalue. */
13354 {
13357 /* Only optimize constant conditions when the selected branch
13358 has the same type as the COND_EXPR. This avoids optimizing
13359 away "c ? x : throw", where the throw has a void type.
13360 Avoid throwing away that operand which contains label. */
13367 }
13369 {
13374 {
13379 {
13387 }
13391 }
13392 }
13394 /* If we have A op B ? A : C, we may be able to convert this to a
13395 simpler expression, depending on the operation and the values
13396 of B and C. Signed zeros prevent all of these transformations,
13397 for reasons given above each one.
13399 Also try swapping the arguments and inverting the conditional. */
13404 {
13408 }
13412 op2,
13415 {
13419 {
13423 }
13424 }
13426 /* If the second operand is simpler than the third, swap them
13427 since that produces better jump optimization results. */
13430 {
13432 /* See if this can be inverted. If it can't, possibly because
13433 it was a floating-point inequality comparison, don't do
13434 anything. */
13438 }
13440 /* Convert A ? 1 : 0 to simply A. */
13445 /* If we try to convert OP0 to our type, the
13446 call to fold will try to move the conversion inside
13447 a COND, which will recurse. In that case, the COND_EXPR
13448 is probably the best choice, so leave it alone. */
13452 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13453 over COND_EXPR in cases such as floating point comparisons. */
13462 arg0)));
13464 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13469 {
13470 /* sign_bit_p looks through both zero and sign extensions,
13471 but for this optimization only sign extensions are
13472 usable. */
13475 {
13478 {
13481 }
13483 }
13484 /* sign_bit_p only checks ARG1 bits within A's precision.
13485 If <sign bit of A> has wider type than A, bits outside
13486 of A's precision in <sign bit of A> need to be checked.
13487 If they are all 0, this optimization needs to be done
13488 in unsigned A's type, if they are all 1 in signed A's type,
13489 otherwise this can't be done. */
13495 {
13497 tree tem_type;
13510 {
13513 }
13515 {
13518 }
13519 else
13521 }
13524 return
13530 arg1)));
13531 }
13533 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13534 already handled above. */
13539 {
13548 }
13550 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13551 is probably obsolete because the first operand should be a
13552 truth value (that's why we have the two cases above), but let's
13553 leave it in until we can confirm this for all front-ends. */
13565 /* Disable the transformations below for vectors, since
13566 fold_binary_op_with_conditional_arg may undo them immediately,
13567 yielding an infinite loop. */
13571 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13580 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13585 {
13587 /* Only perform transformation if ARG0 is easily inverted. */
13591 ? BIT_IOR_EXPR
13594 arg1);
13595 }
13597 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13602 {
13604 /* Only perform transformation if ARG0 is easily inverted. */
13610 op2);
13611 }
13613 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13625 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13626 of fold_ternary on them. */
13636 {
13646 {
13651 {
13659 }
13661 /* Constructor elements can be subvectors. */
13664 {
13668 }
13670 /* We keep an exact subset of the constructor elements. */
13672 {
13678 {
13682 }
13690 CONSTRUCTOR_ELT
13693 }
13694 /* The bitfield references a single constructor element. */
13696 {
13701 else
13705 }
13706 }
13707 }
13709 /* A bit-field-ref that referenced the full argument can be stripped. */
13715 /* On constants we can use native encode/interpret to constant
13716 fold (nearly) all BIT_FIELD_REFs. */
13720 /* This limitation should not be necessary, we just need to
13721 round this up to mode size. */
13723 /* Need bit-shifting of the buffer to relax the following. */
13725 {
13730 /* ??? We cannot tell native_encode_expr to start at
13731 some random byte only. So limit us to a reasonable amount
13732 of work. */
13734 {
13739 {
13745 }
13746 }
13747 }
13752 /* For integers we can decompose the FMA if possible. */
13764 {
13780 {
13785 /* Make sure that the perm value is in an acceptable
13786 range. */
13795 else
13800 }
13803 {
13808 }
13813 {
13818 }
13824 {
13828 }
13833 /* Some targets are deficient and fail to expand a single
13834 argument permutation while still allowing an equivalent
13835 2-argument version. */
13839 {
13842 }
13845 {
13852 }
13856 }
13862 }
13864 /* Perform constant folding and related simplification of EXPR.
13865 The related simplifications include x*1 => x, x*0 => 0, etc.,
13866 and application of the associative law.
13867 NOP_EXPR conversions may be removed freely (as long as we
13868 are careful not to change the type of the overall expression).
13869 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13870 but we can constant-fold them if they have constant operands. */
13872 #ifdef ENABLE_FOLD_CHECKING
13873 # define fold(x) fold_1 (x)
13875 static
13876 #endif
13877 tree
13879 {
13883 tree tem;
13886 /* Return right away if a constant. */
13890 /* CALL_EXPR-like objects with variable numbers of operands are
13891 treated specially. */
13893 {
13895 {
13898 }
13900 }
13903 {
13908 {
13926 }
13927 }
13930 {
13932 {
13939 {
13944 /* Find a matching index by means of a binary search. */
13946 {
13962 else
13964 }
13965 }
13968 }
13970 /* Return a VECTOR_CST if possible. */
13972 {
13979 tree value;
13982 {
13986 {
13989 }
13990 else
13992 }
13997 }
14005 }
14007 #ifdef ENABLE_FOLD_CHECKING
14008 #undef fold
14015 /* When --enable-checking=fold, compute a digest of expr before
14016 and after actual fold call to see if fold did not accidentally
14017 change original expr. */
14019 tree
14021 {
14022 tree ret;
14042 }
14044 void
14046 {
14057 }
14059 static void
14061 {
14063 }
14065 static void
14068 {
14074 recursive_label:
14084 {
14085 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
14090 }
14097 {
14098 /* Allow these fields to be modified. */
14099 tree tmp;
14107 {
14110 }
14111 }
14122 {
14125 {
14140 }
14144 {
14157 }
14174 {
14180 }
14183 {
14185 {
14188 }
14190 }
14201 {
14204 }
14214 }
14215 }
14217 /* Helper function for outputting the checksum of a tree T. When
14218 debugging with gdb, you can "define mynext" to be "next" followed
14219 by "call debug_fold_checksum (op0)", then just trace down till the
14220 outputs differ. */
14222 DEBUG_FUNCTION void
14224 {
14239 }
14241 #endif
14243 /* Fold a unary tree expression with code CODE of type TYPE with an
14244 operand OP0. LOC is the location of the resulting expression.
14245 Return a folded expression if successful. Otherwise, return a tree
14246 expression with code CODE of type TYPE with an operand OP0. */
14248 tree
14251 {
14252 tree tem;
14253 #ifdef ENABLE_FOLD_CHECKING
14262 #endif
14268 #ifdef ENABLE_FOLD_CHECKING
14275 #endif
14277 }
14279 /* Fold a binary tree expression with code CODE of type TYPE with
14280 operands OP0 and OP1. LOC is the location of the resulting
14281 expression. Return a folded expression if successful. Otherwise,
14282 return a tree expression with code CODE of type TYPE with operands
14283 OP0 and OP1. */
14285 tree
14288 MEM_STAT_DECL)
14289 {
14290 tree tem;
14291 #ifdef ENABLE_FOLD_CHECKING
14308 #endif
14314 #ifdef ENABLE_FOLD_CHECKING
14329 #endif
14331 }
14333 /* Fold a ternary tree expression with code CODE of type TYPE with
14334 operands OP0, OP1, and OP2. Return a folded expression if
14335 successful. Otherwise, return a tree expression with code CODE of
14336 type TYPE with operands OP0, OP1, and OP2. */
14338 tree
14341 {
14342 tree tem;
14343 #ifdef ENABLE_FOLD_CHECKING
14367 #endif
14374 #ifdef ENABLE_FOLD_CHECKING
14397 #endif
14399 }
14401 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14402 arguments in ARGARRAY, and a null static chain.
14403 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14404 of type TYPE from the given operands as constructed by build_call_array. */
14406 tree
14409 {
14410 tree tem;
14411 #ifdef ENABLE_FOLD_CHECKING
14430 #endif
14436 #ifdef ENABLE_FOLD_CHECKING
14452 #endif
14454 }
14456 /* Perform constant folding and related simplification of initializer
14457 expression EXPR. These behave identically to "fold_buildN" but ignore
14458 potential run-time traps and exceptions that fold must preserve. */
14460 #define START_FOLD_INIT \
14461 int saved_signaling_nans = flag_signaling_nans;\
14462 int saved_trapping_math = flag_trapping_math;\
14463 int saved_rounding_math = flag_rounding_math;\
14464 int saved_trapv = flag_trapv;\
14465 int saved_folding_initializer = folding_initializer;\
14466 flag_signaling_nans = 0;\
14467 flag_trapping_math = 0;\
14468 flag_rounding_math = 0;\
14469 flag_trapv = 0;\
14470 folding_initializer = 1;
14472 #define END_FOLD_INIT \
14473 flag_signaling_nans = saved_signaling_nans;\
14474 flag_trapping_math = saved_trapping_math;\
14475 flag_rounding_math = saved_rounding_math;\
14476 flag_trapv = saved_trapv;\
14477 folding_initializer = saved_folding_initializer;
14479 tree
14482 {
14483 tree result;
14484 START_FOLD_INIT;
14488 END_FOLD_INIT;
14490 }
14492 tree
14495 {
14496 tree result;
14497 START_FOLD_INIT;
14501 END_FOLD_INIT;
14503 }
14505 tree
14508 {
14509 tree result;
14510 START_FOLD_INIT;
14514 END_FOLD_INIT;
14516 }
14518 #undef START_FOLD_INIT
14519 #undef END_FOLD_INIT
14521 /* Determine if first argument is a multiple of second argument. Return 0 if
14522 it is not, or we cannot easily determined it to be.
14524 An example of the sort of thing we care about (at this point; this routine
14525 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14526 fold cases do now) is discovering that
14528 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14530 is a multiple of
14532 SAVE_EXPR (J * 8)
14534 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14536 This code also handles discovering that
14538 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14540 is a multiple of 8 so we don't have to worry about dealing with a
14541 possible remainder.
14543 Note that we *look* inside a SAVE_EXPR only to determine how it was
14544 calculated; it is not safe for fold to do much of anything else with the
14545 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14546 at run time. For example, the latter example above *cannot* be implemented
14547 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14548 evaluation time of the original SAVE_EXPR is not necessarily the same at
14549 the time the new expression is evaluated. The only optimization of this
14550 sort that would be valid is changing
14552 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14554 divided by 8 to
14556 SAVE_EXPR (I) * SAVE_EXPR (J)
14558 (where the same SAVE_EXPR (J) is used in the original and the
14559 transformed version). */
14561 int
14563 {
14571 {
14573 /* Bitwise and provides a power of two multiple. If the mask is
14574 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14577 /* FALLTHRU */
14590 {
14594 /* const_binop may not detect overflow correctly,
14595 so check for it explicitly here. */
14599 size_one_node,
14600 op1)))
14603 }
14607 /* Can't handle conversions from non-integral or wider integral type. */
14613 /* .. fall through ... */
14630 SIGNED);
14634 }
14635 }
14637 /* Return true if CODE or TYPE is known to be non-negative. */
14639 static bool
14641 {
14644 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14645 have a signed:1 type (where the value is -1 and 0). */
14648 }
14650 /* Return true if (CODE OP0) is known to be non-negative. If the return
14651 value is based on the assumption that signed overflow is undefined,
14652 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14653 *STRICT_OVERFLOW_P. */
14655 bool
14658 {
14663 {
14665 /* We can't return 1 if flag_wrapv is set because
14666 ABS_EXPR<INT_MIN> = INT_MIN. */
14670 {
14673 }
14680 strict_overflow_p);
14682 CASE_CONVERT:
14683 {
14688 {
14691 strict_overflow_p);
14693 {
14697 strict_overflow_p);
14698 }
14699 }
14701 {
14704 strict_overflow_p);
14708 }
14709 }
14714 }
14716 /* We don't know sign of `t', so be conservative and return false. */
14718 }
14720 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14721 value is based on the assumption that signed overflow is undefined,
14722 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14723 *STRICT_OVERFLOW_P. */
14725 bool
14728 {
14733 {
14738 strict_overflow_p)
14740 strict_overflow_p));
14742 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14743 both unsigned and at least 2 bits shorter than the result. */
14747 {
14752 {
14756 }
14757 }
14762 {
14763 /* x * x is always non-negative for floating point x
14764 or without overflow. */
14768 {
14773 }
14774 }
14776 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14777 both unsigned and their total bits is shorter than the result. */
14781 {
14800 {
14810 }
14811 }
14817 strict_overflow_p)
14819 strict_overflow_p));
14830 strict_overflow_p)
14832 strict_overflow_p));
14839 strict_overflow_p);
14842 }
14844 /* We don't know sign of `t', so be conservative and return false. */
14846 }
14848 /* Return true if T is known to be non-negative. If the return
14849 value is based on the assumption that signed overflow is undefined,
14850 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14851 *STRICT_OVERFLOW_P. */
14853 bool
14855 {
14860 {
14872 strict_overflow_p)
14874 strict_overflow_p));
14878 }
14879 /* We don't know sign of `t', so be conservative and return false. */
14881 }
14883 /* Return true if T is known to be non-negative. If the return
14884 value is based on the assumption that signed overflow is undefined,
14885 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14886 *STRICT_OVERFLOW_P. */
14888 bool
14891 {
14894 {
14914 /* Always true. */
14918 /* sqrt(-0.0) is -0.0. */
14922 strict_overflow_p);
14959 /* True if the 1st argument is nonnegative. */
14961 strict_overflow_p);
14964 /* True if the 1st OR 2nd arguments are nonnegative. */
14966 strict_overflow_p)
14968 strict_overflow_p)));
14971 /* True if the 1st AND 2nd arguments are nonnegative. */
14973 strict_overflow_p)
14975 strict_overflow_p)));
14978 /* True if the 2nd argument is nonnegative. */
14980 strict_overflow_p);
14983 /* True if the 1st argument is nonnegative or the second
14984 argument is an even integer. */
14989 strict_overflow_p);
14992 /* True if the 1st argument is nonnegative or the second
14993 argument is an even integer valued real. */
14995 {
14996 REAL_VALUE_TYPE c;
14997 HOST_WIDE_INT n;
15002 {
15003 REAL_VALUE_TYPE cint;
15007 }
15008 }
15010 strict_overflow_p);
15014 }
15016 type);
15017 }
15019 /* Return true if T is known to be non-negative. If the return
15020 value is based on the assumption that signed overflow is undefined,
15021 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15022 *STRICT_OVERFLOW_P. */
15024 static bool
15026 {
15032 {
15034 {
15038 /* If the initializer is non-void, then it's a normal expression
15039 that will be assigned to the slot. */
15043 /* Otherwise, the initializer sets the slot in some way. One common
15044 way is an assignment statement at the end of the initializer. */
15046 {
15054 else
15056 }
15060 strict_overflow_p);
15063 }
15066 {
15072 arg0,
15073 arg1,
15074 strict_overflow_p);
15075 }
15079 strict_overflow_p);
15082 strict_overflow_p);
15085 strict_overflow_p);
15090 }
15092 /* We don't know sign of `t', so be conservative and return false. */
15094 }
15096 /* Return true if T is known to be non-negative. If the return
15097 value is based on the assumption that signed overflow is undefined,
15098 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15099 *STRICT_OVERFLOW_P. */
15101 bool
15103 {
15110 {
15117 strict_overflow_p);
15123 strict_overflow_p);
15132 }
15135 {
15143 strict_overflow_p);
15148 strict_overflow_p);
15161 }
15162 }
15164 /* Return true if `t' is known to be non-negative. Handle warnings
15165 about undefined signed overflow. */
15167 bool
15169 {
15176 "determining that expression is always "
15178 WARN_STRICT_OVERFLOW_MISC);
15180 }
15183 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15184 For floating point we further ensure that T is not denormal.
15185 Similar logic is present in nonzero_address in rtlanal.h.
15187 If the return value is based on the assumption that signed overflow
15188 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15189 change *STRICT_OVERFLOW_P. */
15191 bool
15194 {
15196 {
15199 strict_overflow_p);
15202 {
15208 strict_overflow_p));
15209 }
15214 strict_overflow_p);
15218 }
15221 }
15223 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15224 For floating point we further ensure that T is not denormal.
15225 Similar logic is present in nonzero_address in rtlanal.h.
15227 If the return value is based on the assumption that signed overflow
15228 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15229 change *STRICT_OVERFLOW_P. */
15231 bool
15233 tree type,
15234 tree op0,
15236 {
15239 {
15243 {
15244 /* With the presence of negative values it is hard
15245 to say something. */
15252 /* One of operands must be positive and the other non-negative. */
15253 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15254 overflows, on a twos-complement machine the sum of two
15255 nonnegative numbers can never be zero. */
15257 strict_overflow_p)
15259 strict_overflow_p));
15260 }
15265 {
15267 strict_overflow_p)
15269 strict_overflow_p))
15270 {
15273 }
15274 }
15283 {
15286 }
15293 {
15297 /* When both operands are nonzero, then MAX must be too. */
15299 strict_overflow_p))
15302 /* MAX where operand 0 is positive is positive. */
15304 strict_overflow_p);
15305 }
15306 /* MAX where operand 1 is positive is positive. */
15311 {
15315 }
15320 strict_overflow_p)
15322 strict_overflow_p));
15326 }
15329 }
15331 /* Return true when T is an address and is known to be nonzero.
15332 For floating point we further ensure that T is not denormal.
15333 Similar logic is present in nonzero_address in rtlanal.h.
15335 If the return value is based on the assumption that signed overflow
15336 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15337 change *STRICT_OVERFLOW_P. */
15339 bool
15341 {
15344 {
15349 {
15358 /* For objects in symbol table check if we know they are non-zero.
15359 Don't do anything for variables and functions before symtab is built;
15360 it is quite possible that they will be declared weak later. */
15362 {
15368 else
15370 }
15372 /* Function local objects are never NULL. */
15379 /* Constants are never weak. */
15384 }
15392 {
15396 }
15401 }
15403 }
15405 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15406 attempt to fold the expression to a constant without modifying TYPE,
15407 OP0 or OP1.
15409 If the expression could be simplified to a constant, then return
15410 the constant. If the expression would not be simplified to a
15411 constant, then return NULL_TREE. */
15413 tree
15415 {
15418 }
15420 /* Given the components of a unary expression CODE, TYPE and OP0,
15421 attempt to fold the expression to a constant without modifying
15422 TYPE or OP0.
15424 If the expression could be simplified to a constant, then return
15425 the constant. If the expression would not be simplified to a
15426 constant, then return NULL_TREE. */
15428 tree
15430 {
15433 }
15435 /* If EXP represents referencing an element in a constant string
15436 (either via pointer arithmetic or array indexing), return the
15437 tree representing the value accessed, otherwise return NULL. */
15439 tree
15441 {
15445 {
15447 tree index;
15448 tree string;
15453 else
15454 {
15458 /* Optimize the special-case of a zero lower bound.
15460 We convert the low_bound to sizetype to avoid some problems
15461 with constant folding. (E.g. suppose the lower bound is 1,
15462 and its mode is QI. Without the conversion,l (ARRAY
15463 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15464 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15470 }
15483 }
15485 }
15487 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15488 an integer constant, real, or fixed-point constant.
15490 TYPE is the type of the result. */
15492 static tree
15494 {
15498 {
15500 {
15507 }
15514 {
15515 FIXED_VALUE_TYPE f;
15520 /* Propagate overflow flags. */
15524 }
15528 }
15531 }
15533 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15534 an integer constant or real constant.
15536 TYPE is the type of the result. */
15538 tree
15540 {
15544 {
15546 {
15547 /* If the value is unsigned or non-negative, then the absolute value
15548 is the same as the ordinary value. */
15552 /* If the value is negative, then the absolute value is
15553 its negation. */
15554 else
15555 {
15560 }
15561 }
15567 else
15573 }
15576 }
15578 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15579 constant. TYPE is the type of the result. */
15581 static tree
15583 {
15587 }
15589 /* Given CODE, a relational operator, the target type, TYPE and two
15590 constant operands OP0 and OP1, return the result of the
15591 relational operation. If the result is not a compile time
15592 constant, then return NULL_TREE. */
15594 static tree
15596 {
15599 /* From here on, the only cases we handle are when the result is
15600 known to be a constant. */
15603 {
15607 /* Handle the cases where either operand is a NaN. */
15609 {
15611 {
15639 }
15642 }
15645 }
15648 {
15652 }
15654 /* Handle equality/inequality of complex constants. */
15656 {
15667 else
15669 }
15672 {
15679 {
15691 }
15694 }
15696 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15698 To compute GT, swap the arguments and do LT.
15699 To compute GE, do LT and invert the result.
15700 To compute LE, swap the arguments, do LT and invert the result.
15701 To compute NE, do EQ and invert the result.
15703 Therefore, the code below must handle only EQ and LT. */
15706 {
15711 }
15713 /* Note that it is safe to invert for real values here because we
15714 have already handled the one case that it matters. */
15718 {
15721 }
15723 /* Compute a result for LT or EQ if args permit;
15724 Otherwise return T. */
15726 {
15729 else
15731 }
15732 else
15738 }
15740 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15741 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15742 itself. */
15744 tree
15746 {
15747 /* If the expression does not have side effects then we don't have to wrap
15748 it with a cleanup point expression. */
15752 /* If the expression is a return, check to see if the expression inside the
15753 return has no side effects or the right hand side of the modify expression
15754 inside the return. If either don't have side effects set we don't need to
15755 wrap the expression in a cleanup point expression. Note we don't check the
15756 left hand side of the modify because it should always be a return decl. */
15758 {
15765 }
15768 }
15770 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15771 of an indirection through OP0, or NULL_TREE if no simplification is
15772 possible. */
15774 tree
15776 {
15778 tree subtype;
15786 {
15789 /* *&CONST_DECL -> to the value of the const decl. */
15792 /* *&p => p; make sure to handle *&"str"[cst] here. */
15794 {
15798 else
15800 }
15801 /* *(foo *)&fooarray => fooarray[0] */
15804 && (!in_gimple_form
15806 {
15816 }
15817 /* *(foo *)&complexfoo => __real__ complexfoo */
15821 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15824 {
15828 }
15829 }
15833 {
15839 {
15840 tree op00type;
15844 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15847 {
15859 }
15860 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15863 {
15867 }
15868 /* ((foo *)&fooarray)[1] => fooarray[1] */
15871 {
15881 }
15882 }
15883 }
15885 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15888 && (!in_gimple_form
15890 {
15891 tree type_domain;
15901 NULL_TREE);
15902 }
15905 }
15907 /* Builds an expression for an indirection through T, simplifying some
15908 cases. */
15910 tree
15912 {
15920 }
15922 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15924 tree
15926 {
15931 else
15933 }
15935 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15936 whose result is ignored. The type of the returned tree need not be
15937 the same as the original expression. */
15939 tree
15941 {
15947 {
15958 else
15964 {
15980 }
15985 }
15986 }
15988 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15990 tree
15992 {
15998 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15999 have to do anything. Only do this when we are not given a const,
16000 because in that case, this check is more expensive than just
16001 doing it. */
16003 {
16008 }
16010 /* If divisor is a power of two, simplify this to bit manipulation. */
16012 {
16014 {
16028 }
16029 else
16030 {
16031 tree t;
16037 }
16038 }
16039 else
16040 {
16045 }
16048 }
16050 /* Likewise, but round down. */
16052 tree
16054 {
16061 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16062 have to do anything. Only do this when we are not given a const,
16063 because in that case, this check is more expensive than just
16064 doing it. */
16066 {
16071 }
16073 /* If divisor is a power of two, simplify this to bit manipulation. */
16075 {
16076 tree t;
16080 }
16081 else
16082 {
16087 }
16090 }
16092 /* Returns the pointer to the base of the object addressed by EXP and
16093 extracts the information about the offset of the access, storing it
16094 to PBITPOS and POFFSET. */
16096 static tree
16099 {
16100 tree core;
16101 machine_mode mode;
16103 HOST_WIDE_INT bitsize;
16107 {
16112 }
16113 else
16114 {
16118 }
16121 }
16123 /* Returns true if addresses of E1 and E2 differ by a constant, false
16124 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16126 bool
16128 {
16142 {
16152 }
16154 {
16155 /* If only one of the offsets is non-constant, the difference cannot
16156 be a constant. */
16158 }
16159 else
16164 }
16166 /* Simplify the floating point expression EXP when the sign of the
16167 result is not significant. Return NULL_TREE if no simplification
16168 is possible. */
16170 tree
16172 {
16177 {
16213 {
16216 {
16218 /* Strip copysign function call, return the 1st argument. */
16224 /* Strip sign ops from the argument of "odd" math functions. */
16226 {
16230 }
16232 }
16233 }
16238 }
16240 }
16242 /* Return OFF converted to a pointer offset type suitable as offset for
16243 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16244 tree
16246 {
16248 }
16250 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16251 tree
16253 {
16256 }
16258 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16259 tree
16261 {
16264 }