| blob | 1476ee0b1edecba7ca86a927518efd0ef2b11624 |
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 {
2938 /* Require equal access sizes, and similar pointer types.
2939 We can have incomplete types for array references of
2940 variable-sized arrays from the Fortran frontend
2941 though. Also verify the types are compatible. */
2949 || (alias_ptr_types_compatible_p
2961 /* TARGET_MEM_REF require equal extra operands. */
2969 /* Operands 2 and 3 may be null.
2970 Compare the array index by value if it is constant first as we
2971 may have different types but same value here. */
2982 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2983 may be NULL when we're called to compare MEM_EXPRs. */
2998 }
3002 {
3020 /* The multiplcation operands are commutative. */
3021 /* FALLTHRU */
3029 /* Otherwise take into account this is a commutative operation. */
3042 }
3046 {
3050 /* If not both CALL_EXPRs are either internal or normal function
3051 functions, then they are not equal. */
3054 {
3055 /* If the CALL_EXPRs call different internal functions, then they
3056 are not equal. */
3059 }
3060 else
3061 {
3062 /* If the CALL_EXPRs call different functions, then they are not
3063 equal. */
3065 flags))
3067 }
3069 {
3073 else
3077 }
3079 /* Now see if all the arguments are the same. */
3080 {
3091 /* If we get here and both argument lists are exhausted
3092 then the CALL_EXPRs are equal. */
3094 }
3097 }
3100 /* Consider __builtin_sqrt equal to sqrt. */
3108 }
3110 #undef OP_SAME
3111 #undef OP_SAME_WITH_NULL
3112 }
3113 \f
3114 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3115 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3117 When in doubt, return 0. */
3119 static int
3121 {
3133 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3134 and see if the inner values are the same. This removes any
3135 signedness comparison, which doesn't matter here. */
3142 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3143 actual comparison operand, ARG0.
3145 First throw away any conversions to wider types
3146 already present in the operands. */
3155 {
3158 /* Make sure shorter operand is extended the right way
3159 to match the longer operand. */
3165 }
3168 }
3169 \f
3170 /* See if ARG is an expression that is either a comparison or is performing
3171 arithmetic on comparisons. The comparisons must only be comparing
3172 two different values, which will be stored in *CVAL1 and *CVAL2; if
3173 they are nonzero it means that some operands have already been found.
3174 No variables may be used anywhere else in the expression except in the
3175 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3176 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3178 If this is true, return 1. Otherwise, return zero. */
3180 static int
3182 {
3186 /* We can handle some of the tcc_expression cases here. */
3196 {
3197 /* If we've already found a CVAL1 or CVAL2, this expression is
3198 two complex to handle. */
3204 }
3207 {
3230 /* First see if we can handle the first operand, then the second. For
3231 the second operand, we know *CVAL1 can't be zero. It must be that
3232 one side of the comparison is each of the values; test for the
3233 case where this isn't true by failing if the two operands
3234 are the same. */
3243 ;
3247 ;
3248 else
3252 ;
3256 ;
3257 else
3264 }
3265 }
3266 \f
3267 /* ARG is a tree that is known to contain just arithmetic operations and
3268 comparisons. Evaluate the operations in the tree substituting NEW0 for
3269 any occurrence of OLD0 as an operand of a comparison and likewise for
3270 NEW1 and OLD1. */
3272 static tree
3275 {
3280 /* We can handle some of the tcc_expression cases here. */
3288 {
3303 {
3322 }
3323 /* Fall through - ??? */
3326 {
3330 /* We need to check both for exact equality and tree equality. The
3331 former will be true if the operand has a side-effect. In that
3332 case, we know the operand occurred exactly once. */
3345 }
3349 }
3350 }
3351 \f
3352 /* Return a tree for the case when the result of an expression is RESULT
3353 converted to TYPE and OMITTED was previously an operand of the expression
3354 but is now not needed (e.g., we folded OMITTED * 0).
3356 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3357 the conversion of RESULT to TYPE. */
3359 tree
3361 {
3364 /* If the resulting operand is an empty statement, just return the omitted
3365 statement casted to void. */
3375 }
3377 /* Return a tree for the case when the result of an expression is RESULT
3378 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3379 of the expression but are now not needed.
3381 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3382 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3383 evaluated before OMITTED2. Otherwise, if neither has side effects,
3384 just do the conversion of RESULT to TYPE. */
3386 tree
3389 {
3398 }
3400 \f
3401 /* Return a simplified tree node for the truth-negation of ARG. This
3402 never alters ARG itself. We assume that ARG is an operation that
3403 returns a truth value (0 or 1).
3405 FIXME: one would think we would fold the result, but it causes
3406 problems with the dominator optimizer. */
3408 static tree
3410 {
3415 /* If this is a comparison, we can simply invert it, except for
3416 floating-point non-equality comparisons, in which case we just
3417 enclose a TRUTH_NOT_EXPR around what we have. */
3420 {
3423 && flag_trapping_math
3434 }
3437 {
3456 /* Here we can invert either operand. We invert the first operand
3457 unless the second operand is a TRUTH_NOT_EXPR in which case our
3458 result is the XOR of the first operand with the inside of the
3459 negation of the second operand. */
3464 else
3487 {
3494 /* A COND_EXPR may have a throw as one operand, which
3495 then has void type. Just leave void operands
3496 as they are. */
3502 }
3514 CASE_CONVERT:
3518 /* ... fall through ... */
3540 }
3541 }
3543 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3544 assume that ARG is an operation that returns a truth value (0 or 1
3545 for scalars, 0 or -1 for vectors). Return the folded expression if
3546 folding is successful. Otherwise, return NULL_TREE. */
3548 static tree
3550 {
3553 ? BIT_NOT_EXPR
3556 }
3558 /* Return a simplified tree node for the truth-negation of ARG. This
3559 never alters ARG itself. We assume that ARG is an operation that
3560 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3562 tree
3564 {
3570 ? BIT_NOT_EXPR
3573 }
3575 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3576 operands are another bit-wise operation with a common input. If so,
3577 distribute the bit operations to save an operation and possibly two if
3578 constants are involved. For example, convert
3579 (A | B) & (A | C) into A | (B & C)
3580 Further simplification will occur if B and C are constants.
3582 If this optimization cannot be done, 0 will be returned. */
3584 static tree
3587 {
3588 tree common;
3598 {
3602 }
3604 {
3608 }
3610 {
3614 }
3616 {
3620 }
3621 else
3629 }
3631 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3632 with code CODE. This optimization is unsafe. */
3633 static tree
3636 {
3640 /* (A / C) +- (B / C) -> (A +- B) / C. */
3650 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3655 {
3667 }
3670 }
3671 \f
3672 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3673 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3675 static tree
3678 {
3682 {
3689 }
3703 }
3705 /* Optimize a bit-field compare.
3707 There are two cases: First is a compare against a constant and the
3708 second is a comparison of two items where the fields are at the same
3709 bit position relative to the start of a chunk (byte, halfword, word)
3710 large enough to contain it. In these cases we can avoid the shift
3711 implicit in bitfield extractions.
3713 For constants, we emit a compare of the shifted constant with the
3714 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3715 compared. For two fields at the same position, we do the ANDs with the
3716 similar mask and compare the result of the ANDs.
3718 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3719 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3720 are the left and right operands of the comparison, respectively.
3722 If the optimization described above can be done, we return the resulting
3723 tree. Otherwise we return zero. */
3725 static tree
3728 {
3731 tree unsigned_type;
3737 tree mask;
3738 tree offset;
3740 /* Get all the information about the extractions being done. If the bit size
3741 if the same as the size of the underlying object, we aren't doing an
3742 extraction at all and so can do nothing. We also don't want to
3743 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3744 then will no longer be able to replace it. */
3752 {
3753 /* If this is not a constant, we can only do something if bit positions,
3754 sizes, and signedness are the same. */
3762 }
3764 /* See if we can find a mode to refer to this field. We should be able to,
3765 but fail if we can't. */
3774 /* Set signed and unsigned types of the precision of this mode for the
3775 shifts below. */
3778 /* Compute the bit position and size for the new reference and our offset
3779 within it. If the new reference is the same size as the original, we
3780 won't optimize anything, so return zero. */
3790 /* Make the mask to be used against the extracted field. */
3797 /* If not comparing with constant, just rework the comparison
3798 and return. */
3802 unsigned_type,
3805 mask),
3808 unsigned_type,
3811 mask));
3813 /* Otherwise, we are handling the constant case. See if the constant is too
3814 big for the field. Warn and return a tree of for 0 (false) if so. We do
3815 this not only for its own sake, but to avoid having to test for this
3816 error case below. If we didn't, we might generate wrong code.
3818 For unsigned fields, the constant shifted right by the field length should
3819 be all zero. For signed fields, the high-order bits should agree with
3820 the sign bit. */
3823 {
3825 {
3829 }
3830 }
3831 else
3832 {
3835 {
3839 }
3840 }
3842 /* Single-bit compares should always be against zero. */
3844 {
3847 }
3849 /* Make a new bitfield reference, shift the constant over the
3850 appropriate number of bits and mask it with the computed mask
3851 (in case this was a signed field). If we changed it, make a new one. */
3858 mask);
3863 }
3864 \f
3865 /* Subroutine for fold_truth_andor_1: decode a field reference.
3867 If EXP is a comparison reference, we return the innermost reference.
3869 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3870 set to the starting bit number.
3872 If the innermost field can be completely contained in a mode-sized
3873 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3875 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3876 otherwise it is not changed.
3878 *PUNSIGNEDP is set to the signedness of the field.
3880 *PMASK is set to the mask used. This is either contained in a
3881 BIT_AND_EXPR or derived from the width of the field.
3883 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3885 Return 0 if this is not a component reference or is one that we can't
3886 do anything with. */
3888 static tree
3893 {
3897 tree unsigned_type;
3900 /* All the optimizations using this function assume integer fields.
3901 There are problems with FP fields since the type_for_size call
3902 below can fail for, e.g., XFmode. */
3906 /* We are interested in the bare arrangement of bits, so strip everything
3907 that doesn't affect the machine mode. However, record the type of the
3908 outermost expression if it may matter below. */
3915 {
3921 }
3930 /* If the number of bits in the reference is the same as the bitsize of
3931 the outer type, then the outer type gives the signedness. Otherwise
3932 (in case of a small bitfield) the signedness is unchanged. */
3936 /* Compute the mask to access the bitfield. */
3945 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3953 }
3955 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3956 bit positions and MASK is SIGNED. */
3958 static int
3960 {
3964 /* If this function returns true when the type of the mask is
3965 UNSIGNED, then there will be errors. In particular see
3966 gcc.c-torture/execute/990326-1.c. There does not appear to be
3967 any documentation paper trail as to why this is so. But the pre
3968 wide-int worked with that restriction and it has been preserved
3969 here. */
3974 }
3976 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3977 represents the sign bit of EXP's type. If EXP represents a sign
3978 or zero extension, also test VAL against the unextended type.
3979 The return value is the (sub)expression whose sign bit is VAL,
3980 or NULL_TREE otherwise. */
3982 tree
3984 {
3986 tree t;
3988 /* Tree EXP must have an integral type. */
3993 /* Tree VAL must be an integer constant. */
4002 /* Handle extension from a narrower type. */
4008 }
4010 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4011 to be evaluated unconditionally. */
4013 static int
4015 {
4016 /* Strip any conversions that don't change the machine mode. */
4025 /* Don't regard global variables as simple. They may be
4026 allocated in ways unknown to the compiler (shared memory,
4027 #pragma weak, etc). */
4030 /* Weakrefs are not safe to be read, since they can be NULL.
4031 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4032 have DECL_WEAK flag set. */
4034 /* Loading a static variable is unduly expensive, but global
4035 registers aren't expensive. */
4037 }
4039 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4040 to be evaluated unconditionally.
4041 I addition to simple_operand_p, we assume that comparisons, conversions,
4042 and logic-not operations are simple, if their operands are simple, too. */
4044 static bool
4046 {
4066 }
4068 \f
4069 /* The following functions are subroutines to fold_range_test and allow it to
4070 try to change a logical combination of comparisons into a range test.
4072 For example, both
4073 X == 2 || X == 3 || X == 4 || X == 5
4074 and
4075 X >= 2 && X <= 5
4076 are converted to
4077 (unsigned) (X - 2) <= 3
4079 We describe each set of comparisons as being either inside or outside
4080 a range, using a variable named like IN_P, and then describe the
4081 range with a lower and upper bound. If one of the bounds is omitted,
4082 it represents either the highest or lowest value of the type.
4084 In the comments below, we represent a range by two numbers in brackets
4085 preceded by a "+" to designate being inside that range, or a "-" to
4086 designate being outside that range, so the condition can be inverted by
4087 flipping the prefix. An omitted bound is represented by a "-". For
4088 example, "- [-, 10]" means being outside the range starting at the lowest
4089 possible value and ending at 10, in other words, being greater than 10.
4090 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4091 always false.
4093 We set up things so that the missing bounds are handled in a consistent
4094 manner so neither a missing bound nor "true" and "false" need to be
4095 handled using a special case. */
4097 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4098 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4099 and UPPER1_P are nonzero if the respective argument is an upper bound
4100 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4101 must be specified for a comparison. ARG1 will be converted to ARG0's
4102 type if both are specified. */
4104 static tree
4107 {
4108 tree tem;
4112 /* If neither arg represents infinity, do the normal operation.
4113 Else, if not a comparison, return infinity. Else handle the special
4114 comparison rules. Note that most of the cases below won't occur, but
4115 are handled for consistency. */
4118 {
4123 }
4128 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4129 for neither. In real maths, we cannot assume open ended ranges are
4130 the same. But, this is computer arithmetic, where numbers are finite.
4131 We can therefore make the transformation of any unbounded range with
4132 the value Z, Z being greater than any representable number. This permits
4133 us to treat unbounded ranges as equal. */
4137 {
4158 }
4161 }
4162 \f
4163 /* Helper routine for make_range. Perform one step for it, return
4164 new expression if the loop should continue or NULL_TREE if it should
4165 stop. */
4167 tree
4171 {
4177 {
4179 /* We can only do something if the range is testing for zero. */
4188 /* We can only do something if the range is testing for zero
4189 and if the second operand is an integer constant. Note that
4190 saying something is "in" the range we make is done by
4191 complementing IN_P since it will set in the initial case of
4192 being not equal to zero; "out" is leaving it alone. */
4199 {
4220 }
4222 /* If this is an unsigned comparison, we also know that EXP is
4223 greater than or equal to zero. We base the range tests we make
4224 on that fact, so we record it here so we can parse existing
4225 range tests. We test arg0_type since often the return type
4226 of, e.g. EQ_EXPR, is boolean. */
4228 {
4232 NULL_TREE))
4237 /* If the high bound is missing, but we have a nonzero low
4238 bound, reverse the range so it goes from zero to the low bound
4239 minus 1. */
4241 {
4246 }
4247 }
4255 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4256 low and high are non-NULL, then normalize will DTRT. */
4259 {
4264 }
4266 /* (-x) IN [a,b] -> x in [-b, -a] */
4278 /* ~ X -> -X - 1 */
4287 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4288 move a constant to the other side. */
4293 /* If EXP is signed, any overflow in the computation is undefined,
4294 so we don't worry about it so long as our computations on
4295 the bounds don't overflow. For unsigned, overflow is defined
4296 and this is exactly the right thing. */
4308 normalize:
4309 /* Check for an unsigned range which has wrapped around the maximum
4310 value thus making n_high < n_low, and normalize it. */
4312 {
4318 /* If the range is of the form +/- [ x+1, x ], we won't
4319 be able to normalize it. But then, it represents the
4320 whole range or the empty set, so make it
4321 +/- [ -, - ]. */
4325 else
4327 }
4328 else
4336 CASE_CONVERT:
4354 /* If we're converting arg0 from an unsigned type, to exp,
4355 a signed type, we will be doing the comparison as unsigned.
4356 The tests above have already verified that LOW and HIGH
4357 are both positive.
4359 So we have to ensure that we will handle large unsigned
4360 values the same way that the current signed bounds treat
4361 negative values. */
4364 {
4365 tree high_positive;
4366 tree equiv_type;
4367 /* For fixed-point modes, we need to pass the saturating flag
4368 as the 2nd parameter. */
4370 equiv_type
4373 else
4374 equiv_type
4377 /* A range without an upper bound is, naturally, unbounded.
4378 Since convert would have cropped a very large value, use
4379 the max value for the destination type. */
4380 high_positive
4387 high_positive),
4390 /* If the low bound is specified, "and" the range with the
4391 range for which the original unsigned value will be
4392 positive. */
4394 {
4397 integer_zero_node),
4398 high_positive))
4402 }
4403 else
4404 {
4405 /* Otherwise, "or" the range with the range of the input
4406 that will be interpreted as negative. */
4409 integer_zero_node),
4410 high_positive))
4414 }
4415 }
4424 }
4425 }
4427 /* Given EXP, a logical expression, set the range it is testing into
4428 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4429 actually being tested. *PLOW and *PHIGH will be made of the same
4430 type as the returned expression. If EXP is not a comparison, we
4431 will most likely not be returning a useful value and range. Set
4432 *STRICT_OVERFLOW_P to true if the return value is only valid
4433 because signed overflow is undefined; otherwise, do not change
4434 *STRICT_OVERFLOW_P. */
4436 tree
4439 {
4447 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4448 and see if we can refine the range. Some of the cases below may not
4449 happen, but it doesn't seem worth worrying about this. We "continue"
4450 the outer loop when we've changed something; otherwise we "break"
4451 the switch, which will "break" the while. */
4457 {
4463 {
4471 }
4480 }
4482 /* If EXP is a constant, we can evaluate whether this is true or false. */
4484 {
4491 }
4495 }
4496 \f
4497 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4498 type, TYPE, return an expression to test if EXP is in (or out of, depending
4499 on IN_P) the range. Return 0 if the test couldn't be created. */
4501 tree
4504 {
4507 #ifdef HAVE_canonicalize_funcptr_for_compare
4508 /* Disable this optimization for function pointer expressions
4509 on targets that require function pointer canonicalization. */
4514 #endif
4517 {
4523 }
4541 {
4543 {
4547 }
4549 }
4551 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4553 {
4557 {
4559 {
4562 etype
4564 else
4567 }
4570 }
4571 }
4573 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4574 This requires wrap-around arithmetics for the type of the expression.
4575 First make sure that arithmetics in this type is valid, then make sure
4576 that it wraps around. */
4582 {
4585 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4586 for the type in question, as we rely on this here. */
4596 else
4598 }
4608 {
4610 {
4615 }
4617 }
4625 }
4626 \f
4627 /* Return the predecessor of VAL in its type, handling the infinite case. */
4629 static tree
4631 {
4637 else
4640 }
4642 /* Return the successor of VAL in its type, handling the infinite case. */
4644 static tree
4646 {
4652 else
4655 }
4657 /* Given two ranges, see if we can merge them into one. Return 1 if we
4658 can, 0 if we can't. Set the output range into the specified parameters. */
4660 bool
4663 {
4667 tree tem;
4677 /* Make range 0 be the range that starts first, or ends last if they
4678 start at the same value. Swap them if it isn't. */
4681 || (lowequal
4684 {
4688 }
4690 /* Now flag two cases, whether the ranges are disjoint or whether the
4691 second range is totally subsumed in the first. Note that the tests
4692 below are simplified by the ones above. */
4698 /* We now have four cases, depending on whether we are including or
4699 excluding the two ranges. */
4701 {
4702 /* If they don't overlap, the result is false. If the second range
4703 is a subset it is the result. Otherwise, the range is from the start
4704 of the second to the end of the first. */
4709 else
4711 }
4714 {
4715 /* If they don't overlap, the result is the first range. If they are
4716 equal, the result is false. If the second range is a subset of the
4717 first, and the ranges begin at the same place, we go from just after
4718 the end of the second range to the end of the first. If the second
4719 range is not a subset of the first, or if it is a subset and both
4720 ranges end at the same place, the range starts at the start of the
4721 first range and ends just before the second range.
4722 Otherwise, we can't describe this as a single range. */
4728 {
4733 {
4734 /* We are in the weird situation where high0 > high1 but
4735 high1 has no successor. Punt. */
4737 }
4738 }
4740 {
4745 {
4746 /* low0 < low1 but low1 has no predecessor. Punt. */
4748 }
4749 }
4750 else
4752 }
4755 {
4756 /* If they don't overlap, the result is the second range. If the second
4757 is a subset of the first, the result is false. Otherwise,
4758 the range starts just after the first range and ends at the
4759 end of the second. */
4764 else
4765 {
4770 {
4771 /* high1 > high0 but high0 has no successor. Punt. */
4773 }
4774 }
4775 }
4777 else
4778 {
4779 /* The case where we are excluding both ranges. Here the complex case
4780 is if they don't overlap. In that case, the only time we have a
4781 range is if they are adjacent. If the second is a subset of the
4782 first, the result is the first. Otherwise, the range to exclude
4783 starts at the beginning of the first range and ends at the end of the
4784 second. */
4786 {
4791 else
4792 {
4793 /* Canonicalize - [min, x] into - [-, x]. */
4796 {
4801 /* FALLTHROUGH */
4814 }
4816 /* Canonicalize - [x, max] into - [x, -]. */
4819 {
4824 /* FALLTHROUGH */
4840 }
4842 /* The ranges might be also adjacent between the maximum and
4843 minimum values of the given type. For
4844 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4845 return + [x + 1, y - 1]. */
4847 {
4854 }
4855 else
4857 }
4858 }
4861 else
4863 }
4867 }
4868 \f
4870 /* Subroutine of fold, looking inside expressions of the form
4871 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4872 of the COND_EXPR. This function is being used also to optimize
4873 A op B ? C : A, by reversing the comparison first.
4875 Return a folded expression whose code is not a COND_EXPR
4876 anymore, or NULL_TREE if no folding opportunity is found. */
4878 static tree
4881 {
4886 tree tem;
4891 /* If we have A op 0 ? A : -A, consider applying the following
4892 transformations:
4894 A == 0? A : -A same as -A
4895 A != 0? A : -A same as A
4896 A >= 0? A : -A same as abs (A)
4897 A > 0? A : -A same as abs (A)
4898 A <= 0? A : -A same as -abs (A)
4899 A < 0? A : -A same as -abs (A)
4901 None of these transformations work for modes with signed
4902 zeros. If A is +/-0, the first two transformations will
4903 change the sign of the result (from +0 to -0, or vice
4904 versa). The last four will fix the sign of the result,
4905 even though the original expressions could be positive or
4906 negative, depending on the sign of A.
4908 Note that all these transformations are correct if A is
4909 NaN, since the two alternatives (A and -A) are also NaNs. */
4916 /* In the case that A is of the form X-Y, '-A' (arg2) may
4917 have already been folded to Y-X, check for that. */
4925 {
4939 /* Fall through. */
4961 }
4963 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4964 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4965 both transformations are correct when A is NaN: A != 0
4966 is then true, and A == 0 is false. */
4970 {
4975 }
4977 /* Try some transformations of A op B ? A : B.
4979 A == B? A : B same as B
4980 A != B? A : B same as A
4981 A >= B? A : B same as max (A, B)
4982 A > B? A : B same as max (B, A)
4983 A <= B? A : B same as min (A, B)
4984 A < B? A : B same as min (B, A)
4986 As above, these transformations don't work in the presence
4987 of signed zeros. For example, if A and B are zeros of
4988 opposite sign, the first two transformations will change
4989 the sign of the result. In the last four, the original
4990 expressions give different results for (A=+0, B=-0) and
4991 (A=-0, B=+0), but the transformed expressions do not.
4993 The first two transformations are correct if either A or B
4994 is a NaN. In the first transformation, the condition will
4995 be false, and B will indeed be chosen. In the case of the
4996 second transformation, the condition A != B will be true,
4997 and A will be chosen.
4999 The conversions to max() and min() are not correct if B is
5000 a number and A is not. The conditions in the original
5001 expressions will be false, so all four give B. The min()
5002 and max() versions would give a NaN instead. */
5005 /* Avoid these transformations if the COND_EXPR may be used
5006 as an lvalue in the C++ front-end. PR c++/19199. */
5007 && (in_gimple_form
5013 {
5018 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5020 {
5024 }
5027 {
5036 /* In C++ a ?: expression can be an lvalue, so put the
5037 operand which will be used if they are equal first
5038 so that we can convert this back to the
5039 corresponding COND_EXPR. */
5041 {
5050 }
5057 {
5066 }
5081 }
5082 }
5084 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5085 we might still be able to simplify this. For example,
5086 if C1 is one less or one more than C2, this might have started
5087 out as a MIN or MAX and been transformed by this function.
5088 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5094 {
5098 /* We can replace A with C1 in this case. */
5103 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5104 MIN_EXPR, to preserve the signedness of the comparison. */
5106 OEP_ONLY_CONST)
5110 OEP_ONLY_CONST))
5111 {
5114 arg2));
5117 }
5121 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5122 as above. */
5124 OEP_ONLY_CONST)
5128 OEP_ONLY_CONST))
5129 {
5132 arg2));
5135 }
5139 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5140 MAX_EXPR, to preserve the signedness of the comparison. */
5142 OEP_ONLY_CONST)
5146 OEP_ONLY_CONST))
5147 {
5150 arg2));
5152 }
5156 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5158 OEP_ONLY_CONST)
5162 OEP_ONLY_CONST))
5163 {
5166 arg2));
5168 }
5174 }
5177 }
5180 \f
5181 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5182 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5183 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5184 false) >= 2)
5185 #endif
5187 /* EXP is some logical combination of boolean tests. See if we can
5188 merge it into some range test. Return the new tree if so. */
5190 static tree
5193 {
5209 /* If this is an OR operation, invert both sides; we will invert
5210 again at the end. */
5214 /* If both expressions are the same, if we can merge the ranges, and we
5215 can build the range test, return it or it inverted. If one of the
5216 ranges is always true or always false, consider it to be the same
5217 expression as the other. */
5225 {
5229 }
5231 /* On machines where the branch cost is expensive, if this is a
5232 short-circuited branch and the underlying object on both sides
5233 is the same, make a non-short-circuit operation. */
5239 {
5240 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5241 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5242 which cases we can't do this. */
5250 {
5259 {
5262 WARN_STRICT_OVERFLOW_COMPARISON);
5266 }
5267 }
5268 }
5271 }
5272 \f
5273 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5274 bit value. Arrange things so the extra bits will be set to zero if and
5275 only if C is signed-extended to its full width. If MASK is nonzero,
5276 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5278 static tree
5280 {
5283 tree temp;
5288 /* We work by getting just the sign bit into the low-order bit, then
5289 into the high-order bit, then sign-extend. We then XOR that value
5290 with C. */
5293 /* We must use a signed type in order to get an arithmetic right shift.
5294 However, we must also avoid introducing accidental overflows, so that
5295 a subsequent call to integer_zerop will work. Hence we must
5296 do the type conversion here. At this point, the constant is either
5297 zero or one, and the conversion to a signed type can never overflow.
5298 We could get an overflow if this conversion is done anywhere else. */
5307 /* If necessary, convert the type back to match the type of C. */
5312 }
5313 \f
5314 /* For an expression that has the form
5315 (A && B) || ~B
5316 or
5317 (A || B) && ~B,
5318 we can drop one of the inner expressions and simplify to
5319 A || ~B
5320 or
5321 A && ~B
5322 LOC is the location of the resulting expression. OP is the inner
5323 logical operation; the left-hand side in the examples above, while CMPOP
5324 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5325 removing a condition that guards another, as in
5326 (A != NULL && A->...) || A == NULL
5327 which we must not transform. If RHS_ONLY is true, only eliminate the
5328 right-most operand of the inner logical operation. */
5330 static tree
5333 {
5351 {
5354 {
5357 }
5358 }
5360 {
5363 {
5366 }
5367 }
5382 }
5384 /* Find ways of folding logical expressions of LHS and RHS:
5385 Try to merge two comparisons to the same innermost item.
5386 Look for range tests like "ch >= '0' && ch <= '9'".
5387 Look for combinations of simple terms on machines with expensive branches
5388 and evaluate the RHS unconditionally.
5390 For example, if we have p->a == 2 && p->b == 4 and we can make an
5391 object large enough to span both A and B, we can do this with a comparison
5392 against the object ANDed with the a mask.
5394 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5395 operations to do this with one comparison.
5397 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5398 function and the one above.
5400 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5401 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5403 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5404 two operands.
5406 We return the simplified tree or 0 if no optimization is possible. */
5408 static tree
5411 {
5412 /* If this is the "or" of two comparisons, we can do something if
5413 the comparisons are NE_EXPR. If this is the "and", we can do something
5414 if the comparisons are EQ_EXPR. I.e.,
5415 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5417 WANTED_CODE is this operation code. For single bit fields, we can
5418 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5419 comparison for one-bit fields. */
5439 /* Start by getting the comparison codes. Fail if anything is volatile.
5440 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5441 it were surrounded with a NE_EXPR. */
5450 {
5454 }
5457 {
5461 }
5472 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5475 {
5478 {
5483 }
5486 {
5492 }
5493 }
5498 /* If the RHS can be evaluated unconditionally and its operands are
5499 simple, it wins to evaluate the RHS unconditionally on machines
5500 with expensive branches. In this case, this isn't a comparison
5501 that can be merged. */
5508 {
5509 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5520 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5530 }
5532 /* See if the comparisons can be merged. Then get all the parameters for
5533 each side. */
5557 /* It must be true that the inner operation on the lhs of each
5558 comparison must be the same if we are to be able to do anything.
5559 Then see if we have constants. If not, the same must be true for
5560 the rhs's. */
5571 else
5574 /* If either comparison code is not correct for our logical operation,
5575 fail. However, we can convert a one-bit comparison against zero into
5576 the opposite comparison against that bit being set in the field. */
5580 {
5582 {
5583 /* Make the left operand unsigned, since we are only interested
5584 in the value of one bit. Otherwise we are doing the wrong
5585 thing below. */
5588 }
5589 else
5591 }
5593 /* This is analogous to the code for l_const above. */
5595 {
5597 {
5600 }
5601 else
5603 }
5605 /* See if we can find a mode that contains both fields being compared on
5606 the left. If we can't, fail. Otherwise, update all constants and masks
5607 to be relative to a field of that size. */
5612 volatilep);
5622 {
5625 }
5633 {
5640 {
5644 }
5645 }
5647 {
5654 {
5658 }
5659 }
5661 /* If the right sides are not constant, do the same for it. Also,
5662 disallow this optimization if a size or signedness mismatch occurs
5663 between the left and right sides. */
5665 {
5668 /* Make sure the two fields on the right
5669 correspond to the left without being swapped. */
5677 volatilep);
5687 {
5690 }
5699 /* Make a mask that corresponds to both fields being compared.
5700 Do this for both items being compared. If the operands are the
5701 same size and the bits being compared are in the same position
5702 then we can do this by masking both and comparing the masked
5703 results. */
5707 {
5719 }
5721 /* There is still another way we can do something: If both pairs of
5722 fields being compared are adjacent, we may be able to make a wider
5723 field containing them both.
5725 Note that we still must mask the lhs/rhs expressions. Furthermore,
5726 the mask must be shifted to account for the shift done by
5727 make_bit_field_ref. */
5732 {
5733 tree type;
5747 /* Convert to the smaller type before masking out unwanted bits. */
5750 {
5752 {
5756 }
5758 {
5762 }
5763 }
5772 }
5775 }
5777 /* Handle the case of comparisons with constants. If there is something in
5778 common between the masks, those bits of the constants must be the same.
5779 If not, the condition is always false. Test for this to avoid generating
5780 incorrect code below. */
5785 {
5787 {
5790 }
5791 else
5792 {
5795 }
5796 }
5798 /* Construct the expression we will return. First get the component
5799 reference we will make. Unless the mask is all ones the width of
5800 that field, perform the mask operation. Then compare with the
5801 merged constant. */
5811 }
5812 \f
5813 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5814 constant. */
5816 static tree
5819 {
5822 tree comp_const;
5823 tree minmax_const;
5825 tree inner;
5836 /* If something does not permit us to optimize, return the original tree. */
5844 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5845 and GT_EXPR, doing the rest with recursive calls using logical
5846 simplifications. */
5848 {
5850 {
5851 tree tem
5858 }
5861 return
5863 optimize_minmax_comparison
5865 optimize_minmax_comparison
5870 /* MAX (X, 0) == 0 -> X <= 0 */
5874 /* MAX (X, 0) == 5 -> X == 5 */
5878 /* MAX (X, 0) == -1 -> false */
5882 /* MIN (X, 0) == 0 -> X >= 0 */
5886 /* MIN (X, 0) == 5 -> false */
5889 else
5890 /* MIN (X, 0) == -1 -> X == -1 */
5895 /* MAX (X, 0) > 0 -> X > 0
5896 MAX (X, 0) > 5 -> X > 5 */
5900 /* MAX (X, 0) > -1 -> true */
5904 /* MIN (X, 0) > 0 -> false
5905 MIN (X, 0) > 5 -> false */
5908 else
5909 /* MIN (X, 0) > -1 -> X > -1 */
5914 }
5915 }
5916 \f
5917 /* T is an integer expression that is being multiplied, divided, or taken a
5918 modulus (CODE says which and what kind of divide or modulus) by a
5919 constant C. See if we can eliminate that operation by folding it with
5920 other operations already in T. WIDE_TYPE, if non-null, is a type that
5921 should be used for the computation if wider than our type.
5923 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5924 (X * 2) + (Y * 4). We must, however, be assured that either the original
5925 expression would not overflow or that overflow is undefined for the type
5926 in the language in question.
5928 If we return a non-null expression, it is an equivalent form of the
5929 original computation, but need not be in the original type.
5931 We set *STRICT_OVERFLOW_P to true if the return values depends on
5932 signed overflow being undefined. Otherwise we do not change
5933 *STRICT_OVERFLOW_P. */
5935 static tree
5938 {
5939 /* To avoid exponential search depth, refuse to allow recursion past
5940 three levels. Beyond that (1) it's highly unlikely that we'll find
5941 something interesting and (2) we've probably processed it before
5942 when we built the inner expression. */
5945 tree ret;
5950 depth++;
5952 depth--;
5955 }
5957 static tree
5960 {
5971 /* Don't deal with constants of zero here; they confuse the code below. */
5981 /* Note that we need not handle conditional operations here since fold
5982 already handles those cases. So just do arithmetic here. */
5984 {
5986 /* For a constant, we can always simplify if we are a multiply
5987 or (for divide and modulus) if it is a multiple of our constant. */
5995 /* If op0 is an expression ... */
6001 /* ... and has wrapping overflow, and its type is smaller
6002 than ctype, then we cannot pass through as widening. */
6007 /* ... or this is a truncation (t is narrower than op0),
6008 then we cannot pass through this narrowing. */
6011 /* ... or signedness changes for division or modulus,
6012 then we cannot pass through this conversion. */
6016 /* ... or has undefined overflow while the converted to
6017 type has not, we cannot do the operation in the inner type
6018 as that would introduce undefined overflow. */
6024 /* Pass the constant down and see if we can make a simplification. If
6025 we can, replace this expression with the inner simplification for
6026 possible later conversion to our or some other type. */
6031 code == MULT_EXPR
6033 strict_overflow_p))))
6038 /* If widening the type changes it from signed to unsigned, then we
6039 must avoid building ABS_EXPR itself as unsigned. */
6041 {
6045 {
6048 }
6050 }
6051 /* If the constant is negative, we cannot simplify this. */
6054 /* FALLTHROUGH */
6056 /* For division and modulus, type can't be unsigned, as e.g.
6057 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6058 For signed types, even with wrapping overflow, this is fine. */
6067 /* If widening the type changes the signedness, then we can't perform
6068 this optimization as that changes the result. */
6072 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6078 {
6085 }
6089 /* If the second operand is constant, this is a multiplication
6090 or floor division, by a power of two, so we can treat it that
6091 way unless the multiplier or divisor overflows. Signed
6092 left-shift overflow is implementation-defined rather than
6093 undefined in C90, so do not convert signed left shift into
6094 multiplication. */
6097 /* const_binop may not detect overflow correctly,
6098 so check for it explicitly here. */
6102 size_one_node,
6103 op1)))
6107 ctype,
6109 t1),
6114 /* See if we can eliminate the operation on both sides. If we can, we
6115 can return a new PLUS or MINUS. If we can't, the only remaining
6116 cases where we can do anything are if the second operand is a
6117 constant. */
6123 /* If not multiplication, we can only do this if both operands
6124 are divisible by c. */
6127 {
6132 }
6134 /* If this was a subtraction, negate OP1 and set it to be an addition.
6135 This simplifies the logic below. */
6137 {
6139 /* If OP1 was not easily negatable, the constant may be OP0. */
6141 {
6144 }
6145 }
6150 /* If either OP1 or C are negative, this optimization is not safe for
6151 some of the division and remainder types while for others we need
6152 to change the code. */
6154 {
6162 }
6164 /* If it's a multiply or a division/modulus operation of a multiple
6165 of our constant, do the operation and verify it doesn't overflow. */
6168 {
6171 /* We allow the constant to overflow with wrapping semantics. */
6175 }
6176 else
6179 /* If we have an unsigned type, we cannot widen the operation since it
6180 will change the result if the original computation overflowed. */
6184 /* If we were able to eliminate our operation from the first side,
6185 apply our operation to the second side and reform the PLUS. */
6189 /* The last case is if we are a multiply. In that case, we can
6190 apply the distributive law to commute the multiply and addition
6191 if the multiplication of the constants doesn't overflow
6192 and overflow is defined. With undefined overflow
6193 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6199 op1);
6204 /* We have a special case here if we are doing something like
6205 (C * 8) % 4 since we know that's zero. */
6208 /* If the multiplication can overflow we cannot optimize this. */
6212 {
6215 }
6217 /* ... fall through ... */
6221 /* If we can extract our operation from the LHS, do so and return a
6222 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6223 do something only if the second operand is a constant. */
6237 /* If these are the same operation types, we can associate them
6238 assuming no overflow. */
6240 {
6252 }
6254 /* If these operations "cancel" each other, we have the main
6255 optimizations of this pass, which occur when either constant is a
6256 multiple of the other, in which case we replace this with either an
6257 operation or CODE or TCODE.
6259 If we have an unsigned type, we cannot do this since it will change
6260 the result if the original computation overflowed. */
6267 {
6269 {
6276 }
6278 {
6285 }
6286 }
6291 }
6294 }
6295 \f
6296 /* Return a node which has the indicated constant VALUE (either 0 or
6297 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6298 and is of the indicated TYPE. */
6300 tree
6302 {
6311 else
6313 }
6316 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6317 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6318 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6319 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6320 COND is the first argument to CODE; otherwise (as in the example
6321 given here), it is the second argument. TYPE is the type of the
6322 original expression. Return NULL_TREE if no simplification is
6323 possible. */
6325 static tree
6330 {
6340 {
6344 /* If this operand throws an expression, then it does not make
6345 sense to try to perform a logical or arithmetic operation
6346 involving it. */
6351 }
6352 else
6353 {
6358 }
6363 /* This transformation is only worthwhile if we don't have to wrap ARG
6364 in a SAVE_EXPR and the operation can be simplified without recursing
6365 on at least one of the branches once its pushed inside the COND_EXPR. */
6374 {
6378 else
6380 }
6382 {
6386 else
6388 }
6390 /* Check that we have simplified at least one of the branches. */
6395 }
6397 \f
6398 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6400 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6401 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6402 ADDEND is the same as X.
6404 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6405 and finite. The problematic cases are when X is zero, and its mode
6406 has signed zeros. In the case of rounding towards -infinity,
6407 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6408 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6410 bool
6412 {
6416 /* Don't allow the fold with -fsignaling-nans. */
6420 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6424 /* In a vector or complex, we would need to check the sign of all zeros. */
6428 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6432 /* The mode has signed zeros, and we have to honor their sign.
6433 In this situation, there is only one case we can return true for.
6434 X - 0 is the same as X unless rounding towards -infinity is
6435 supported. */
6437 }
6439 /* Subroutine of fold() that checks comparisons of built-in math
6440 functions against real constants.
6442 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6443 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6444 is the type of the result and ARG0 and ARG1 are the operands of the
6445 comparison. ARG1 must be a TREE_REAL_CST.
6447 The function returns the constant folded tree if a simplification
6448 can be made, and NULL_TREE otherwise. */
6450 static tree
6454 {
6455 REAL_VALUE_TYPE c;
6458 {
6464 {
6465 /* sqrt(x) < y is always false, if y is negative. */
6469 /* sqrt(x) > y is always true, if y is negative and we
6470 don't care about NaNs, i.e. negative values of x. */
6474 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6477 }
6479 {
6480 REAL_VALUE_TYPE c2;
6486 {
6487 /* sqrt(x) > y is x == +Inf, when y is very large. */
6492 /* sqrt(x) > y is always false, when y is very large
6493 and we don't care about infinities. */
6495 }
6497 /* sqrt(x) > c is the same as x > c*c. */
6500 }
6502 {
6503 REAL_VALUE_TYPE c2;
6509 {
6510 /* sqrt(x) < y is always true, when y is a very large
6511 value and we don't care about NaNs or Infinities. */
6515 /* sqrt(x) < y is x != +Inf when y is very large and we
6516 don't care about NaNs. */
6521 /* sqrt(x) < y is x >= 0 when y is very large and we
6522 don't care about Infinities. */
6527 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6532 dconst0)),
6535 c2)));
6536 }
6538 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6543 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6548 dconst0)),
6551 c2)));
6552 }
6553 }
6556 }
6558 /* Subroutine of fold() that optimizes comparisons against Infinities,
6559 either +Inf or -Inf.
6561 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6562 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6563 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6565 The function returns the constant folded tree if a simplification
6566 can be made, and NULL_TREE otherwise. */
6568 static tree
6571 {
6572 machine_mode mode;
6573 REAL_VALUE_TYPE max;
6574 tree temp;
6579 /* For negative infinity swap the sense of the comparison. */
6585 {
6587 /* x > +Inf is always false, if with ignore sNANs. */
6593 /* x <= +Inf is always true, if we don't case about NaNs. */
6597 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6603 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6609 /* x < +Inf is always equal to x <= DBL_MAX. */
6615 /* x != +Inf is always equal to !(x > DBL_MAX). */
6627 }
6630 }
6632 /* Subroutine of fold() that optimizes comparisons of a division by
6633 a nonzero integer constant against an integer constant, i.e.
6634 X/C1 op C2.
6636 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6637 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6638 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6640 The function returns the constant folded tree if a simplification
6641 can be made, and NULL_TREE otherwise. */
6643 static tree
6646 {
6654 /* We have to do this the hard way to detect unsigned overflow.
6655 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6661 {
6666 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6670 }
6672 {
6676 {
6695 }
6696 }
6697 else
6698 {
6699 /* A negative divisor reverses the relational operators. */
6705 {
6724 }
6725 }
6728 {
6749 {
6752 }
6757 {
6760 }
6765 {
6768 }
6773 {
6776 }
6781 }
6784 }
6787 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6788 equality/inequality test, then return a simplified form of the test
6789 using a sign testing. Otherwise return NULL. TYPE is the desired
6790 result type. */
6792 static tree
6795 tree result_type)
6796 {
6797 /* If this is testing a single bit, we can optimize the test. */
6801 {
6802 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6803 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6807 /* This is only a win if casting to a signed type is cheap,
6808 i.e. when arg00's type is not a partial mode. */
6811 {
6814 result_type,
6817 }
6818 }
6821 }
6823 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6824 equality/inequality test, then return a simplified form of
6825 the test using shifts and logical operations. Otherwise return
6826 NULL. TYPE is the desired result type. */
6828 tree
6831 {
6832 /* If this is testing a single bit, we can optimize the test. */
6836 {
6845 /* First, see if we can fold the single bit test into a sign-bit
6846 test. */
6848 result_type);
6852 /* Otherwise we have (A & C) != 0 where C is a single bit,
6853 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6854 Similarly for (A & C) == 0. */
6856 /* If INNER is a right shift of a constant and it plus BITNUM does
6857 not overflow, adjust BITNUM and INNER. */
6863 {
6866 }
6868 /* If we are going to be able to omit the AND below, we must do our
6869 operations as unsigned. If we must use the AND, we have a choice.
6870 Normally unsigned is faster, but for some machines signed is. */
6871 #ifdef LOAD_EXTEND_OP
6874 #else
6876 #endif
6892 /* Put the AND last so it can combine with more things. */
6895 /* Make sure to return the proper type. */
6899 }
6901 }
6903 /* Check whether we are allowed to reorder operands arg0 and arg1,
6904 such that the evaluation of arg1 occurs before arg0. */
6906 static bool
6908 {
6915 }
6917 /* Test whether it is preferable two swap two operands, ARG0 and
6918 ARG1, for example because ARG0 is an integer constant and ARG1
6919 isn't. If REORDER is true, only recommend swapping if we can
6920 evaluate the operands in reverse order. */
6922 bool
6924 {
6942 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6943 for commutative and comparison operators. Ensuring a canonical
6944 form allows the optimizers to find additional redundancies without
6945 having to explicitly check for both orderings. */
6951 /* Put SSA_NAMEs last. */
6957 /* Put variables last. */
6964 }
6966 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6967 ARG0 is extended to a wider type. */
6969 static tree
6972 {
6974 tree arg1_unw;
6983 #ifdef HAVE_canonicalize_funcptr_for_compare
6984 /* Disable this optimization if we're casting a function pointer
6985 type on targets that require function pointer canonicalization. */
6990 #endif
6997 /* If possible, express the comparison in the shorter mode. */
7017 /* If we are comparing with the integer that does not fit into the range
7018 of the shorter type, the result is known. */
7029 {
7056 }
7059 }
7061 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7062 ARG0 just the signedness is changed. */
7064 static tree
7067 {
7068 tree arg0_inner;
7078 #ifdef HAVE_canonicalize_funcptr_for_compare
7079 /* Disable this optimization if we're casting a function pointer
7080 type on targets that require function pointer canonicalization. */
7085 #endif
7106 else
7110 }
7113 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7114 means A >= Y && A != MAX, but in this case we know that
7115 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7117 static tree
7119 {
7126 else
7135 {
7138 }
7140 {
7143 }
7144 else
7151 {
7152 /* Convert the pointer types into integer before taking the difference. */
7156 }
7157 else
7164 }
7166 /* Fold a sum or difference of at least one multiplication.
7167 Returns the folded tree or NULL if no simplification could be made. */
7169 static tree
7172 {
7176 /* (A * C) +- (B * C) -> (A+-B) * C.
7177 (A * C) +- A -> A * (C+-1).
7178 We are most concerned about the case where C is a constant,
7179 but other combinations show up during loop reduction. Since
7180 it is not difficult, try all four possibilities. */
7183 {
7186 }
7188 {
7191 }
7192 else
7193 {
7194 /* We cannot generate constant 1 for fract. */
7199 }
7201 {
7204 }
7206 {
7208 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7209 the purpose of this canonicalization. */
7213 {
7216 }
7217 else
7219 }
7220 else
7221 {
7222 /* We cannot generate constant 1 for fract. */
7227 }
7239 /* No identical multiplicands; see if we can find a common
7240 power-of-two factor in non-power-of-two multiplies. This
7241 can help in multi-dimensional array access. */
7244 {
7247 tree maybe_same;
7251 /* Move min of absolute values to int11. */
7253 {
7258 }
7259 else
7263 /* The remainder should not be a constant, otherwise we
7264 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7265 increased the number of multiplications necessary. */
7267 {
7275 }
7276 }
7286 }
7288 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7289 specified by EXPR into the buffer PTR of length LEN bytes.
7290 Return the number of bytes placed in the buffer, or zero
7291 upon failure. */
7293 static int
7295 {
7309 {
7311 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7312 number of bytes. */
7316 {
7323 else
7325 }
7326 else
7331 }
7333 }
7336 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7337 specified by EXPR into the buffer PTR of length LEN bytes.
7338 Return the number of bytes placed in the buffer, or zero
7339 upon failure. */
7341 static int
7343 {
7347 FIXED_VALUE_TYPE value;
7363 }
7366 /* Subroutine of native_encode_expr. Encode the REAL_CST
7367 specified by EXPR into the buffer PTR of length LEN bytes.
7368 Return the number of bytes placed in the buffer, or zero
7369 upon failure. */
7371 static int
7373 {
7379 /* There are always 32 bits in each long, no matter the size of
7380 the hosts long. We handle floating point representations with
7381 up to 192 bits. */
7395 {
7400 {
7407 else
7409 }
7410 else
7416 }
7418 }
7420 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7421 specified by EXPR into the buffer PTR of length LEN bytes.
7422 Return the number of bytes placed in the buffer, or zero
7423 upon failure. */
7425 static int
7427 {
7429 tree part;
7444 }
7447 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7448 specified by EXPR into the buffer PTR of length LEN bytes.
7449 Return the number of bytes placed in the buffer, or zero
7450 upon failure. */
7452 static int
7454 {
7464 {
7466 {
7469 }
7480 }
7482 }
7485 /* Subroutine of native_encode_expr. Encode the STRING_CST
7486 specified by EXPR into the buffer PTR of length LEN bytes.
7487 Return the number of bytes placed in the buffer, or zero
7488 upon failure. */
7490 static int
7492 {
7494 HOST_WIDE_INT total_bytes;
7508 {
7511 {
7514 }
7517 }
7518 else
7521 }
7524 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7525 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7526 buffer PTR of length LEN bytes. If OFF is not -1 then start
7527 the encoding at byte offset OFF and encode at most LEN bytes.
7528 Return the number of bytes placed in the buffer, or zero upon failure. */
7530 int
7532 {
7534 {
7555 }
7556 }
7559 /* Subroutine of native_interpret_expr. Interpret the contents of
7560 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7561 If the buffer cannot be interpreted, return NULL_TREE. */
7563 static tree
7565 {
7575 }
7578 /* Subroutine of native_interpret_expr. Interpret the contents of
7579 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7580 If the buffer cannot be interpreted, return NULL_TREE. */
7582 static tree
7584 {
7586 double_int result;
7587 FIXED_VALUE_TYPE fixed_value;
7597 }
7600 /* Subroutine of native_interpret_expr. Interpret the contents of
7601 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7602 If the buffer cannot be interpreted, return NULL_TREE. */
7604 static tree
7606 {
7611 /* There are always 32 bits in each long, no matter the size of
7612 the hosts long. We handle floating point representations with
7613 up to 192 bits. */
7614 REAL_VALUE_TYPE r;
7625 {
7628 {
7635 else
7637 }
7638 else
7643 }
7647 }
7650 /* Subroutine of native_interpret_expr. Interpret the contents of
7651 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7652 If the buffer cannot be interpreted, return NULL_TREE. */
7654 static tree
7656 {
7671 }
7674 /* Subroutine of native_interpret_expr. Interpret the contents of
7675 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7676 If the buffer cannot be interpreted, return NULL_TREE. */
7678 static tree
7680 {
7693 {
7698 }
7700 }
7703 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7704 the buffer PTR of length LEN as a constant of type TYPE. For
7705 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7706 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7707 return NULL_TREE. */
7709 tree
7711 {
7713 {
7735 }
7736 }
7738 /* Returns true if we can interpret the contents of a native encoding
7739 as TYPE. */
7741 static bool
7743 {
7745 {
7758 }
7759 }
7761 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7762 TYPE at compile-time. If we're unable to perform the conversion
7763 return NULL_TREE. */
7765 static tree
7767 {
7768 /* We support up to 512-bit values (for V8DFmode). */
7772 /* Check that the host and target are sane. */
7781 }
7783 /* Build an expression for the address of T. Folds away INDIRECT_REF
7784 to avoid confusing the gimplify process. */
7786 tree
7788 {
7789 /* The size of the object is not relevant when talking about its address. */
7794 {
7799 }
7809 {
7814 }
7815 else
7819 }
7821 /* Build an expression for the address of T. */
7823 tree
7825 {
7829 }
7831 /* Fold a unary expression of code CODE and type TYPE with operand
7832 OP0. Return the folded expression if folding is successful.
7833 Otherwise, return NULL_TREE. */
7835 tree
7837 {
7838 tree tem;
7839 tree arg0;
7847 {
7850 {
7851 /* Don't use STRIP_NOPS, because signedness of argument type
7852 matters. */
7854 }
7855 else
7856 {
7857 /* Strip any conversions that don't change the mode. This
7858 is safe for every expression, except for a comparison
7859 expression because its signedness is derived from its
7860 operands.
7862 Note that this is done as an internal manipulation within
7863 the constant folder, in order to find the simplest
7864 representation of the arguments so that their form can be
7865 studied. In any cases, the appropriate type conversions
7866 should be put back in the tree that will get out of the
7867 constant folder. */
7869 }
7872 {
7875 {
7879 }
7880 }
7881 }
7888 {
7895 {
7909 /* If this was a conversion, and all we did was to move into
7910 inside the COND_EXPR, bring it back out. But leave it if
7911 it is a conversion from integer to integer and the
7912 result precision is no wider than a word since such a
7913 conversion is cheap and may be optimized away by combine,
7914 while it couldn't if it were outside the COND_EXPR. Then return
7915 so we don't get into an infinite recursion loop taking the
7916 conversion out and then back in. */
7928 && (INTEGRAL_TYPE_P
7941 }
7942 }
7945 {
7951 CASE_CONVERT:
7955 {
7956 /* If we have (type) (a CMP b) and type is an integral type, return
7957 new expression involving the new type. Canonicalize
7958 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7959 non-integral type.
7960 Do not fold the result as that would not simplify further, also
7961 folding again results in recursions. */
7971 }
7973 /* Handle (T *)&A.B.C for A being of type T and B and C
7974 living at offset zero. This occurs frequently in
7975 C++ upcasting and then accessing the base. */
7979 {
7981 tree offset;
7982 machine_mode mode;
7987 /* If the reference was to a (constant) zero offset, we can use
7988 the address of the base if it has the same base type
7989 as the result type and the pointer type is unqualified. */
7996 }
8000 /* Detect assigning a bitfield. */
8002 && DECL_BIT_FIELD
8004 {
8005 /* Don't leave an assignment inside a conversion
8006 unless assigning a bitfield. */
8008 /* First do the assignment, then return converted constant. */
8013 }
8015 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8016 constants (if x has signed type, the sign bit cannot be set
8017 in c). This folds extension into the BIT_AND_EXPR.
8018 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8019 very likely don't have maximal range for their precision and this
8020 transformation effectively doesn't preserve non-maximal ranges. */
8024 {
8035 <= HOST_BITS_PER_WIDE_INT
8037 {
8041 cst &= HOST_WIDE_INT_M1U
8044 #ifdef LOAD_EXTEND_OP
8046 && !flag_syntax_only
8049 {
8053 }
8054 #endif
8055 }
8057 {
8062 }
8063 }
8065 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8066 when one of the new casts will fold away. Conservatively we assume
8067 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8074 {
8078 return fold_build_pointer_plus_loc
8080 }
8082 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8083 of the same precision, and X is an integer type not narrower than
8084 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8090 {
8096 }
8098 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8099 type of X and Y (integer types only). */
8104 {
8105 /* Be careful not to introduce new overflows. */
8106 tree mult_type;
8109 else
8113 {
8120 }
8121 }
8139 /* Convert fabs((double)float) into (double)fabsf(float). */
8142 {
8148 targ0));
8149 }
8150 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8154 /* Strip sign ops from argument. */
8156 {
8161 }
8168 {
8174 }
8180 /* Convert ~ (-A) to A - 1. */
8185 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8191 {
8192 /* Perform the negation in ARG0's type and only then convert
8193 to TYPE as to avoid introducing undefined behavior. */
8198 }
8199 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8218 /* Note that the operand of this must be an int
8219 and its values must be 0 or 1.
8220 ("true" is a fixed value perhaps depending on the language,
8221 but we don't handle values other than 1 correctly yet.) */
8231 {
8239 }
8241 {
8246 }
8248 {
8252 {
8261 }
8262 }
8269 {
8277 }
8279 {
8283 }
8285 {
8289 {
8298 }
8299 }
8303 /* Fold *&X to X if X is an lvalue. */
8305 {
8312 }
8318 }
8321 /* If the operation was a conversion do _not_ mark a resulting constant
8322 with TREE_OVERFLOW if the original constant was not. These conversions
8323 have implementation defined behavior and retaining the TREE_OVERFLOW
8324 flag here would confuse later passes such as VRP. */
8325 tree
8328 {
8337 }
8339 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8340 operands OP0 and OP1. LOC is the location of the resulting expression.
8341 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8342 Return the folded expression if folding is successful. Otherwise,
8343 return NULL_TREE. */
8344 static tree
8347 {
8348 tree tem;
8350 /* We only do these simplifications if we are optimizing. */
8354 /* Check for things like (A || B) && (A || C). We can convert this
8355 to A || (B && C). Note that either operator can be any of the four
8356 truth and/or operations and the transformation will still be
8357 valid. Also note that we only care about order for the
8358 ANDIF and ORIF operators. If B contains side effects, this
8359 might change the truth-value of A. */
8366 {
8386 /* This case if tricky because we must either have commutative
8387 operators or else A10 must not have side-effects. */
8393 a01);
8394 }
8396 /* See if we can build a range comparison. */
8402 {
8406 }
8410 {
8414 }
8416 /* Check for the possibility of merging component references. If our
8417 lhs is another similar operation, try to merge its rhs with our
8418 rhs. Then try to merge our lhs and rhs. */
8432 {
8439 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8440 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8441 We don't want to pack more than two leafs to a non-IF AND/OR
8442 expression.
8443 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8444 equal to IF-CODE, then we don't want to add right-hand operand.
8445 If the inner right-hand side of left-hand operand has
8446 side-effects, or isn't simple, then we can't add to it,
8447 as otherwise we might destroy if-sequence. */
8450 /* Needed for sequence points to handle trappings, and
8451 side-effects. */
8453 {
8455 arg1);
8457 tem);
8458 }
8459 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8460 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8463 /* Needed for sequence points to handle trappings, and
8464 side-effects. */
8466 {
8471 }
8472 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8473 into (A OR B).
8474 For sequence point consistancy, we need to check for trapping,
8475 and side-effects. */
8479 }
8482 }
8484 /* Fold a binary expression of code CODE and type TYPE with operands
8485 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8486 Return the folded expression if folding is successful. Otherwise,
8487 return NULL_TREE. */
8489 static tree
8491 {
8498 else
8501 /* MIN (MAX (a, b), b) == b. */
8506 /* MIN (MAX (b, a), b) == b. */
8512 /* MIN (a, MAX (a, b)) == a. */
8518 /* MIN (a, MAX (b, a)) == a. */
8525 }
8527 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8528 by changing CODE to reduce the magnitude of constants involved in
8529 ARG0 of the comparison.
8530 Returns a canonicalized comparison tree if a simplification was
8531 possible, otherwise returns NULL_TREE.
8532 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8533 valid if signed overflow is undefined. */
8535 static tree
8539 {
8545 /* Match A +- CST code arg1 and CST code arg1. We can change the
8546 first form only if overflow is undefined. */
8549 /* In principle pointers also have undefined overflow behavior,
8550 but that causes problems elsewhere. */
8558 /* Identify the constant in arg0 and its sign. */
8561 else
8565 /* Overflowed constants and zero will cause problems. */
8570 /* See if we can reduce the magnitude of the constant in
8571 arg0 by changing the comparison code. */
8573 {
8574 /* CST <= arg1 -> CST-1 < arg1. */
8577 /* -CST < arg1 -> -CST-1 <= arg1. */
8580 /* CST > arg1 -> CST-1 >= arg1. */
8583 /* -CST >= arg1 -> -CST-1 > arg1. */
8586 else
8588 /* arg1 code' CST' might be more canonical. */
8590 }
8591 else
8592 {
8593 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8597 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8601 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8605 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8609 else
8612 }
8614 /* Now build the constant reduced in magnitude. But not if that
8615 would produce one outside of its types range. */
8623 /* We cannot swap the comparison here as that would cause us to
8624 endlessly recurse. */
8633 /* If swapping might yield to a more canonical form, do so. */
8636 else
8638 }
8640 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8641 overflow further. Try to decrease the magnitude of constants involved
8642 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8643 and put sole constants at the second argument position.
8644 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8646 static tree
8649 {
8650 tree t;
8655 /* Try canonicalization by simplifying arg0. */
8660 {
8664 }
8666 /* Try canonicalization by simplifying arg1 using the swapped
8667 comparison. */
8675 }
8677 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8678 space. This is used to avoid issuing overflow warnings for
8679 expressions like &p->x which can not wrap. */
8681 static bool
8683 {
8690 wide_int wi_offset;
8696 else
8712 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8713 array. */
8715 {
8716 HOST_WIDE_INT base_size;
8721 }
8724 }
8726 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8727 kind INTEGER_CST. This makes sure to properly sign-extend the
8728 constant. */
8730 static HOST_WIDE_INT
8732 {
8738 }
8740 /* Subroutine of fold_binary. This routine performs all of the
8741 transformations that are common to the equality/inequality
8742 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8743 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8744 fold_binary should call fold_binary. Fold a comparison with
8745 tree code CODE and type TYPE with operands OP0 and OP1. Return
8746 the folded comparison or NULL_TREE. */
8748 static tree
8751 {
8761 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8763 && (equality_code
8770 {
8771 const enum tree_code
8778 /* If the constant operation overflowed this can be
8779 simplified as a comparison against INT_MAX/INT_MIN. */
8782 {
8786 /* Get the sign of the constant on the lhs if the
8787 operation were VARIABLE + CONST1. */
8791 /* The sign of the constant determines if we overflowed
8792 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8793 Canonicalize to the INT_MIN overflow by swapping the comparison
8794 if necessary. */
8798 /* We now can look at the canonicalized case
8799 VARIABLE + 1 CODE2 INT_MIN
8800 and decide on the result. */
8802 {
8806 return
8812 return
8817 }
8818 }
8819 else
8820 {
8823 "when changing X +- C1 cmp C2 to "
8825 WARN_STRICT_OVERFLOW_COMPARISON);
8827 }
8828 }
8830 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8832 && equality_code
8834 {
8835 /* ??? The transformation is valid for the other operators if overflow
8836 is undefined for the type, but performing it here badly interacts
8837 with the transformation in fold_cond_expr_with_comparison which
8838 attempts to synthetize ABS_EXPR. */
8842 WARN_STRICT_OVERFLOW_COMPARISON);
8845 }
8847 /* For comparisons of pointers we can decompose it to a compile time
8848 comparison of the base objects and the offsets into the object.
8849 This requires at least one operand being an ADDR_EXPR or a
8850 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8856 {
8859 machine_mode mode;
8863 /* Get base and offset for the access. Strip ADDR_EXPR for
8864 get_inner_reference, but put it back by stripping INDIRECT_REF
8865 off the base object if possible. indirect_baseN will be true
8866 if baseN is not an address but refers to the object itself. */
8869 {
8875 else
8877 }
8879 {
8883 {
8886 }
8889 {
8894 {
8897 }
8898 }
8899 }
8903 {
8909 else
8911 }
8913 {
8917 {
8920 }
8923 {
8928 {
8931 }
8932 }
8933 }
8935 /* A local variable can never be pointed to by
8936 the default SSA name of an incoming parameter. */
8938 && indirect_base0
8941 && !indirect_base1
8946 && indirect_base1
8949 && !indirect_base0
8953 {
8958 }
8959 /* If we have equivalent bases we might be able to simplify. */
8962 {
8963 /* We can fold this expression to a constant if the non-constant
8964 offset parts are equal. */
8973 {
8979 "occur when comparing P +- C1 with "
8981 WARN_STRICT_OVERFLOW_CONDITIONAL);
8984 {
8998 }
8999 }
9000 /* We can simplify the comparison to a comparison of the variable
9001 offset parts if the constant offset parts are equal.
9002 Be careful to use signed sizetype here because otherwise we
9003 mess with array offsets in the wrong way. This is possible
9004 because pointer arithmetic is restricted to retain within an
9005 object and overflow on pointer differences is undefined as of
9006 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9008 && (equality_code
9011 {
9012 /* By converting to signed sizetype we cover middle-end pointer
9013 arithmetic which operates on unsigned pointer types of size
9014 type size and ARRAY_REF offsets which are properly sign or
9015 zero extended from their type in case it is narrower than
9016 sizetype. */
9019 else
9023 else
9030 "occur when comparing P +- C1 with "
9032 WARN_STRICT_OVERFLOW_COMPARISON);
9035 }
9036 }
9037 /* For non-equal bases we can simplify if they are addresses
9038 declarations with different addresses. */
9040 /* We know that !operand_equal_p (base0, base1, 0)
9041 because the if condition was false. But make
9042 sure two decls are not the same. */
9048 /* Watch for aliases. */
9053 {
9060 }
9061 /* For equal offsets we can simplify to a comparison of the
9062 base addresses. */
9064 && (indirect_base0
9066 && (indirect_base1
9071 {
9077 }
9078 }
9080 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9081 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9082 the resulting offset is smaller in absolute value than the
9083 original one and has the same sign. */
9092 {
9097 tree cst;
9099 "occur when combining constants around "
9102 /* Put the constant on the side where it doesn't overflow and is
9103 of lower absolute value and of same sign than before. */
9110 {
9113 variable1,
9117 }
9125 {
9131 variable2);
9132 }
9133 }
9135 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9136 signed arithmetic case. That form is created by the compiler
9137 often enough for folding it to be of value. One example is in
9138 computing loop trip counts after Operator Strength Reduction. */
9145 {
9151 /* Handle unfolded multiplication by zero. */
9156 "eliminating multiplication in comparison "
9158 WARN_STRICT_OVERFLOW_COMPARISON);
9160 /* If const1 is negative we swap the sense of the comparison. */
9165 }
9172 {
9180 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9186 /* (-a) CMP (-b) -> b CMP a */
9193 {
9194 REAL_VALUE_TYPE cst;
9197 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9204 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9205 /* a CMP (-0) -> a CMP 0 */
9210 /* x != NaN is always true, other ops are always false. */
9213 {
9216 }
9218 /* Fold comparisons against infinity. */
9221 {
9225 }
9226 }
9228 /* If this is a comparison of a real constant with a PLUS_EXPR
9229 or a MINUS_EXPR of a real constant, we can convert it into a
9230 comparison with a revised real constant as long as no overflow
9231 occurs when unsafe_math_optimizations are enabled. */
9243 /* Likewise, we can simplify a comparison of a real constant with
9244 a MINUS_EXPR whose first operand is also a real constant, i.e.
9245 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9246 floating-point types only if -fassociative-math is set. */
9252 arg1))
9257 /* Fold comparisons against built-in math functions. */
9259 && flag_unsafe_math_optimizations
9261 {
9265 {
9269 }
9270 }
9271 }
9275 {
9276 /* If we are widening one operand of an integer comparison,
9277 see if the other operand is similarly being widened. Perhaps we
9278 can do the comparison in the narrower type. */
9283 /* Or if we are changing signedness. */
9287 }
9289 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9290 constant, we can simplify it. */
9295 {
9299 }
9301 /* Simplify comparison of something with itself. (For IEEE
9302 floating-point, we can only do some of these simplifications.) */
9304 {
9306 {
9321 /* For NE, we can only do this simplification if integer
9322 or we don't honor IEEE floating point NaNs. */
9326 /* ... fall through ... */
9332 }
9333 }
9335 /* If we are comparing an expression that just has comparisons
9336 of two integer values, arithmetic expressions of those comparisons,
9337 and constants, we can simplify it. There are only three cases
9338 to check: the two values can either be equal, the first can be
9339 greater, or the second can be greater. Fold the expression for
9340 those three values. Since each value must be 0 or 1, we have
9341 eight possibilities, each of which corresponds to the constant 0
9342 or 1 or one of the six possible comparisons.
9344 This handles common cases like (a > b) == 0 but also handles
9345 expressions like ((x > y) - (y > x)) > 0, which supposedly
9346 occur in macroized code. */
9349 {
9354 /* Don't handle degenerate cases here; they should already
9355 have been handled anyway. */
9364 {
9368 /* We can't just pass T to eval_subst in case cval1 or cval2
9369 was the same as ARG1. */
9371 tree high_result
9375 arg1);
9376 tree equal_result
9380 arg1);
9381 tree low_result
9385 arg1);
9387 /* All three of these results should be 0 or 1. Confirm they are.
9388 Then use those values to select the proper code to use. */
9393 {
9394 /* Make a 3-bit mask with the high-order bit being the
9395 value for `>', the next for '=', and the low for '<'. */
9399 {
9401 /* Always false. */
9422 /* Always true. */
9424 }
9427 {
9431 }
9433 }
9434 }
9435 }
9437 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9438 into a single range test. */
9446 {
9450 }
9452 /* Fold ~X op ~Y as Y op X. */
9455 {
9461 }
9463 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9466 {
9472 }
9475 }
9478 /* Subroutine of fold_binary. Optimize complex multiplications of the
9479 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9480 argument EXPR represents the expression "z" of type TYPE. */
9482 static tree
9484 {
9489 {
9492 }
9494 {
9497 }
9498 else
9499 {
9503 }
9512 }
9515 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9516 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9517 guarantees that P and N have the same least significant log2(M) bits.
9518 N is not otherwise constrained. In particular, N is not normalized to
9519 0 <= N < M as is common. In general, the precise value of P is unknown.
9520 M is chosen as large as possible such that constant N can be determined.
9522 Returns M and sets *RESIDUE to N.
9524 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9525 account. This is not always possible due to PR 35705.
9526 */
9528 static unsigned HOST_WIDE_INT
9531 {
9538 {
9543 }
9545 {
9553 allow_func_align);
9559 {
9562 }
9564 {
9567 {
9570 /* Compute the greatest power-of-2 divisor of op1. */
9574 /* If align is non-zero and less than *modulus, replace
9575 *modulus with align., If align is 0, then either op1 is 0
9576 or the greatest power-of-2 divisor of op1 doesn't fit in an
9577 unsigned HOST_WIDE_INT. In either case, no additional
9578 constraint is imposed. */
9583 }
9584 }
9585 }
9587 /* If we get here, we were unable to determine anything useful about the
9588 expression. */
9590 }
9592 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9593 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9595 static bool
9597 {
9601 {
9604 }
9606 {
9612 else
9614 }
9615 else
9621 }
9623 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9624 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9625 NULL_TREE otherwise. */
9627 static tree
9629 {
9646 {
9650 }
9653 {
9659 }
9660 else
9662 }
9664 /* Try to fold a pointer difference of type TYPE two address expressions of
9665 array references AREF0 and AREF1 using location LOC. Return a
9666 simplified expression for the difference or NULL_TREE. */
9668 static tree
9671 {
9676 /* If the bases are array references as well, recurse. If the bases
9677 are pointer indirections compute the difference of the pointers.
9678 If the bases are equal, we are set. */
9681 && (base_offset
9689 {
9695 base_offset,
9698 }
9700 }
9702 /* If the real or vector real constant CST of type TYPE has an exact
9703 inverse, return it, else return NULL. */
9705 tree
9707 {
9708 REAL_VALUE_TYPE r;
9710 machine_mode mode;
9714 {
9730 {
9735 }
9741 }
9742 }
9744 /* Mask out the tz least significant bits of X of type TYPE where
9745 tz is the number of trailing zeroes in Y. */
9746 static wide_int
9748 {
9753 }
9755 /* Return true when T is an address and is known to be nonzero.
9756 For floating point we further ensure that T is not denormal.
9757 Similar logic is present in nonzero_address in rtlanal.h.
9759 If the return value is based on the assumption that signed overflow
9760 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9761 change *STRICT_OVERFLOW_P. */
9763 static bool
9765 {
9769 /* Doing something useful for floating point would need more work. */
9775 {
9778 strict_overflow_p);
9784 strict_overflow_p);
9792 }
9795 {
9798 strict_overflow_p);
9806 strict_overflow_p);
9821 strict_overflow_p);
9825 strict_overflow_p);
9828 {
9840 }
9844 }
9846 }
9848 /* Return true when T is an address and is known to be nonzero.
9849 Handle warnings about undefined signed overflow. */
9851 static bool
9853 {
9860 "determining that expression is always "
9862 WARN_STRICT_OVERFLOW_MISC);
9864 }
9866 /* Fold a binary expression of code CODE and type TYPE with operands
9867 OP0 and OP1. LOC is the location of the resulting expression.
9868 Return the folded expression if folding is successful. Otherwise,
9869 return NULL_TREE. */
9871 tree
9874 {
9889 /* Strip any conversions that don't change the mode. This is
9890 safe for every expression, except for a comparison expression
9891 because its signedness is derived from its operands. So, in
9892 the latter case, only strip conversions that don't change the
9893 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9894 preserved.
9896 Note that this is done as an internal manipulation within the
9897 constant folder, in order to find the simplest representation
9898 of the arguments so that their form can be studied. In any
9899 cases, the appropriate type conversions should be put back in
9900 the tree that will get out of the constant folder. */
9903 {
9906 }
9907 else
9908 {
9911 }
9913 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9914 constant but we can't do arithmetic on them. */
9916 {
9919 {
9923 }
9924 }
9926 /* If this is a commutative operation, and ARG0 is a constant, move it
9927 to ARG1 to reduce the number of tests below. */
9932 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9933 to ARG1 to reduce the number of tests below. */
9942 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9944 First check for cases where an arithmetic operation is applied to a
9945 compound, conditional, or comparison operation. Push the arithmetic
9946 operation inside the compound or conditional to see if any folding
9947 can then be done. Convert comparison to conditional for this purpose.
9948 The also optimizes non-constant cases that used to be done in
9949 expand_expr.
9951 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9952 one of the operands is a comparison and the other is a comparison, a
9953 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9954 code below would make the expression more complex. Change it to a
9955 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9956 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9969 {
9973 boolean_type_node,
9981 }
9985 {
9987 {
9992 tem);
9993 }
9996 {
10001 tem);
10002 }
10007 {
10013 }
10018 {
10024 }
10025 }
10028 {
10030 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10033 {
10039 }
10041 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10044 {
10045 tree base;
10046 HOST_WIDE_INT coffset;
10055 }
10060 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10066 arg1),
10068 arg0)));
10074 {
10075 /* X + (X / CST) * -CST is X % CST. */
10080 {
10089 cst0));
10090 }
10091 }
10093 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10094 one. Make sure the type is not saturating and has the signedness of
10095 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10096 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10103 {
10107 }
10110 {
10111 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10112 with a constant, and the two constants have no bits in common,
10113 we should treat this as a BIT_IOR_EXPR since this may produce more
10114 simplifications. */
10121 {
10124 }
10126 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10127 (plus (plus (mult) (mult)) (foo)) so that we can
10128 take advantage of the factoring cases below. */
10137 {
10143 else
10156 parg0),
10158 marg)),
10162 return
10168 parg1)));
10169 }
10170 }
10171 else
10172 {
10173 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10174 to __complex__ ( x, y ). This is not the same for SNaNs or
10175 if signed zeros are involved. */
10179 {
10186 {
10190 {
10196 }
10198 {
10204 }
10205 }
10206 }
10214 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10215 We associate floats only if the user has specified
10216 -fassociative-math. */
10220 {
10225 {
10226 tree tree0;
10229 }
10230 }
10231 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10232 We associate floats only if the user has specified
10233 -fassociative-math. */
10237 {
10242 {
10243 tree tree0;
10246 }
10247 }
10248 }
10250 bit_rotate:
10251 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10252 is a rotate of A by C1 bits. */
10253 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10254 is a rotate of A by B bits. */
10255 {
10257 tree rtype;
10266 /* Only create rotates in complete modes. Other cases are not
10267 expanded properly. */
10270 {
10284 {
10288 code0 == LSHIFT_EXPR
10292 }
10294 {
10302 element_precision
10306 return
10309 ? LROTATE_EXPR
10314 }
10316 {
10324 element_precision
10328 return fold_convert_loc
10331 ? LROTATE_EXPR
10335 }
10336 }
10337 }
10339 associate:
10340 /* In most languages, can't associate operations on floats through
10341 parentheses. Rather than remember where the parentheses were, we
10342 don't associate floats at all, unless the user has specified
10343 -fassociative-math.
10344 And, we need to make sure type is not saturating. */
10348 {
10354 /* Split both trees into variables, constants, and literals. Then
10355 associate each group together, the constants with literals,
10356 then the result with variables. This increases the chances of
10357 literals being recombined later and of generating relocatable
10358 expressions for the sum of a constant and literal. */
10363 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10367 /* With undefined overflow prefer doing association in a type
10368 which wraps on overflow, if that is one of the operand types. */
10371 {
10379 }
10381 /* With undefined overflow we can only associate constants with one
10382 variable, and constants whose association doesn't overflow. */
10385 {
10387 {
10405 /* The only case we can still associate with two variables
10406 is if they are the same, modulo negation and bit-pattern
10407 preserving conversions. */
10410 }
10411 }
10413 /* Only do something if we found more than two objects. Otherwise,
10414 nothing has changed and we risk infinite recursion. */
10420 {
10432 /* Preserve the MINUS_EXPR if the negative part of the literal is
10433 greater than the positive part. Otherwise, the multiplicative
10434 folding code (i.e extract_muldiv) may be fooled in case
10435 unsigned constants are subtracted, like in the following
10436 example: ((X*2 + 4) - 8U)/2. */
10438 {
10442 {
10446 }
10447 else
10448 {
10452 }
10453 }
10455 /* Don't introduce overflows through reassociation. */
10462 {
10464 return
10468 else
10469 {
10472 return
10476 }
10477 }
10480 return
10483 }
10484 }
10489 /* Pointer simplifications for subtraction, simple reassociations. */
10491 {
10492 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10495 {
10505 }
10506 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10508 {
10515 }
10516 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10517 simplifies. */
10519 {
10526 arg10);
10529 }
10530 }
10531 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10541 /* X - (X / Y) * Y is X % Y. */
10549 return
10555 {
10556 /* Fold A - (A & B) into ~B & A. */
10559 {
10561 {
10568 }
10570 {
10577 }
10578 }
10580 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10581 any power of 2 minus 1. */
10586 {
10592 {
10596 }
10597 }
10598 }
10600 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10601 __complex__ ( x, -y ). This is not the same for SNaNs or if
10602 signed zeros are involved. */
10606 {
10613 {
10617 {
10619 arg1r ? arg1r
10624 }
10626 {
10630 arg1i ? arg1i
10633 }
10634 }
10635 }
10637 /* A - B -> A + (-B) if B is easily negatable. */
10641 /* Avoid this transformation if B is a positive REAL_CST. */
10650 /* Try folding difference of addresses. */
10651 {
10652 HOST_WIDE_INT diff;
10658 }
10660 /* Fold &a[i] - &a[j] to i-j. */
10665 {
10671 }
10674 && flag_unsafe_math_optimizations
10680 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10681 one. Make sure the type is not saturating and has the signedness of
10682 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10683 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10690 {
10694 }
10699 /* (-A) * (-B) -> A * B */
10714 {
10715 /* Transform x * -C into -x * C if x is easily negatable. */
10724 tem);
10726 /* (a * (1 << b)) is (a << b) */
10736 /* (A + A) * C -> A * 2 * C */
10748 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10749 sign-changing only. */
10759 {
10762 "occur when simplifying "
10764 WARN_STRICT_OVERFLOW_MISC);
10766 }
10768 /* Optimize z * conj(z) for integer complex numbers. */
10775 }
10776 else
10777 {
10778 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10779 the result for floating point types due to rounding so it is applied
10780 only if -fassociative-math was specify. */
10785 {
10787 arg1);
10791 }
10793 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10795 {
10798 {
10801 }
10802 }
10804 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10805 This is not the same for NaNs or if signed zeros are
10806 involved. */
10812 {
10815 return
10821 return
10826 }
10828 /* Optimize z * conj(z) for floating point complex numbers.
10829 Guarded by flag_unsafe_math_optimizations as non-finite
10830 imaginary components don't produce scalar results. */
10841 {
10845 /* Optimizations of root(...)*root(...). */
10847 {
10852 /* Optimize sqrt(x)*sqrt(x) as x. */
10858 /* Optimize root(x)*root(y) as root(x*y). */
10862 }
10864 /* Optimize expN(x)*expN(y) as expN(x+y). */
10866 {
10872 }
10874 /* Optimizations of pow(...)*pow(...). */
10878 {
10884 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10886 {
10891 }
10893 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10895 {
10900 }
10901 }
10903 /* Optimize tan(x)*cos(x) as sin(x). */
10912 {
10918 }
10920 /* Optimize x*pow(x,c) as pow(x,c+1). */
10924 {
10930 {
10932 REAL_VALUE_TYPE c;
10933 tree arg;
10939 }
10940 }
10942 /* Optimize pow(x,c)*x as pow(x,c+1). */
10946 {
10952 {
10954 REAL_VALUE_TYPE c;
10955 tree arg;
10961 }
10962 }
10964 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10966 && optimize
10968 {
10972 {
10975 }
10976 }
10977 }
10978 }
10982 bit_ior:
10983 /* ~X | X is -1. */
10986 {
10990 }
10992 /* X | ~X is -1. */
10995 {
10999 }
11001 /* Canonicalize (X & C1) | C2. */
11005 {
11010 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11018 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11023 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11024 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11025 mode which allows further optimizations. */
11030 {
11034 {
11037 }
11038 }
11045 c3)),
11046 arg1);
11047 }
11049 /* (X & ~Y) | (~X & Y) is X ^ Y */
11052 {
11069 }
11075 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11077 This results in more efficient code for machines without a NAND
11078 instruction. Combine will canonicalize to the first form
11079 which will allow use of NAND instructions provided by the
11080 backend if they exist. */
11083 {
11084 return
11091 }
11093 /* See if this can be simplified into a rotate first. If that
11094 is unsuccessful continue in the association code. */
11098 /* ~X ^ X is -1. */
11101 {
11105 }
11107 /* X ^ ~X is -1. */
11110 {
11114 }
11116 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11117 with a constant, and the two constants have no bits in common,
11118 we should treat this as a BIT_IOR_EXPR since this may produce more
11119 simplifications. */
11126 {
11129 }
11131 /* (X | Y) ^ X -> Y & ~ X*/
11134 {
11137 arg1);
11142 }
11144 /* (Y | X) ^ X -> Y & ~ X*/
11147 {
11150 arg1);
11155 }
11157 /* X ^ (X | Y) -> Y & ~ X*/
11160 {
11163 arg0);
11168 }
11170 /* X ^ (Y | X) -> Y & ~ X*/
11173 {
11176 arg0);
11181 }
11183 /* Convert ~X ^ ~Y to X ^ Y. */
11192 /* Convert ~X ^ C to X ^ ~C. */
11200 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11208 /* Fold (X & Y) ^ Y as ~X & Y. */
11211 {
11216 }
11217 /* Fold (X & Y) ^ X as ~Y & X. */
11221 {
11226 }
11227 /* Fold X ^ (X & Y) as X & ~Y. */
11230 {
11235 }
11236 /* Fold X ^ (Y & X) as ~Y & X. */
11240 {
11245 }
11247 /* See if this can be simplified into a rotate first. If that
11248 is unsuccessful continue in the association code. */
11252 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11260 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11268 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11273 {
11274 tree tem2;
11281 }
11282 /* Fold ~X & 1 as (X & 1) == 0. */
11286 {
11287 tree tem2;
11294 }
11295 /* Fold !X & 1 as X == 0. */
11298 {
11302 }
11304 /* Fold (X ^ Y) & Y as ~X & Y. */
11307 {
11312 }
11313 /* Fold (X ^ Y) & X as ~Y & X. */
11317 {
11322 }
11323 /* Fold X & (X ^ Y) as X & ~Y. */
11326 {
11331 }
11332 /* Fold X & (Y ^ X) as ~Y & X. */
11336 {
11341 }
11343 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11344 multiple of 1 << CST. */
11346 {
11353 }
11355 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11356 bits from CST2. */
11360 {
11368 {
11369 /* Avoid the transform if arg1 is a mask of some
11370 mode which allows further optimizations. */
11377 }
11378 }
11380 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11381 ((A & N) + B) & M -> (A + B) & M
11382 Similarly if (N & M) == 0,
11383 ((A | N) + B) & M -> (A + B) & M
11384 and for - instead of + (or unary - instead of +)
11385 and/or ^ instead of |.
11386 If B is constant and (B & M) == 0, fold into A & M. */
11388 {
11397 {
11400 wide_int cst0;
11402 /* Now we know that arg0 is (C + D) or (C - D) or
11403 -C and arg1 (M) is == (1LL << cst) - 1.
11404 Store C into PMOP[0] and D into PMOP[1]. */
11408 {
11411 }
11418 {
11428 {
11431 }
11434 /* If C or D is of the form (A & N) where
11435 (N & M) == M, or of the form (A | N) or
11436 (A ^ N) where (N & M) == 0, replace it with A. */
11440 /* If C or D is a N where (N & M) == 0, it can be
11441 omitted (assumed 0). */
11449 }
11451 /* Only build anything new if we optimized one or both arguments
11452 above. */
11456 {
11459 {
11460 /* Perform the operations in a type that has defined
11461 overflow behavior. */
11467 }
11472 {
11480 else
11482 }
11485 else
11488 /* TEM is now the new binary +, - or unary - replacement. */
11492 }
11493 }
11494 }
11499 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11502 {
11507 return
11509 }
11511 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11513 This results in more efficient code for machines without a NOR
11514 instruction. Combine will canonicalize to the first form
11515 which will allow use of NOR instructions provided by the
11516 backend if they exist. */
11519 {
11526 }
11528 /* If arg0 is derived from the address of an object or function, we may
11529 be able to fold this expression using the object or function's
11530 alignment. */
11532 {
11539 /* This works because modulus is a power of 2. If this weren't the
11540 case, we'd have to replace it by its greatest power-of-2
11541 divisor: modulus & -modulus. */
11544 }
11546 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11547 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11548 if the new mask might be further optimized. */
11557 {
11568 {
11571 /* See if more bits can be proven as zero because of
11572 zero extension. */
11575 {
11580 {
11582 /* See if we can shorten the right shift. */
11585 /* Otherwise X >> C1 is all zeros, so we'll optimize
11586 it into (X, 0) later on by making sure zerobits
11587 is all ones. */
11588 }
11589 }
11592 {
11595 }
11596 /* For arithmetic shift if sign bit could be set, zerobits
11597 can contain actually sign bits, so no transformation is
11598 possible, unless MASK masks them all away. In that
11599 case the shift needs to be converted into logical shift. */
11602 {
11605 else
11607 }
11608 }
11610 /* ((X << 16) & 0xff00) is (X, 0). */
11617 {
11618 /* Only do the transformation if NEWMASK is some integer
11619 mode's mask. */
11626 {
11627 tree newmaskt;
11630 {
11636 }
11637 else
11642 }
11643 }
11644 }
11649 /* Don't touch a floating-point divide by zero unless the mode
11650 of the constant can represent infinity. */
11656 /* (-A) / (-B) -> A / B */
11666 /* Convert A/B/C to A/(B*C). */
11673 /* Convert A/(B/C) to (A/B)*C. */
11681 /* Convert C1/(X*C2) into (C1/C2)/X. */
11686 {
11692 }
11695 {
11699 /* Optimize sin(x)/cos(x) as tan(x). */
11705 {
11710 }
11712 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11718 {
11722 {
11727 }
11728 }
11730 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11731 NaNs or Infinities. */
11735 {
11742 {
11747 }
11748 }
11750 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11751 NaNs or Infinities. */
11755 {
11762 {
11766 {
11770 tmp);
11771 }
11772 }
11773 }
11775 /* Optimize pow(x,c)/x as pow(x,c-1). */
11779 {
11785 {
11787 REAL_VALUE_TYPE c;
11788 tree arg;
11794 }
11795 }
11797 /* Optimize a/root(b/c) into a*root(c/b). */
11799 {
11803 {
11812 }
11813 }
11815 /* Optimize x/expN(y) into x*expN(-y). */
11817 {
11824 }
11826 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11830 {
11838 }
11839 }
11843 /* Optimize (X & (-A)) / A where A is a power of 2,
11844 to X >> log2(A) */
11848 {
11856 }
11857 }
11859 /* Fall through */
11862 /* Simplify A / (B << N) where A and B are positive and B is
11863 a power of 2, to A >> (N + log2(B)). */
11868 {
11871 {
11879 WARN_STRICT_OVERFLOW_MISC);
11885 }
11886 }
11888 /* Fall through */
11896 /* Convert -A / -B to A / B when the type is signed and overflow is
11897 undefined. */
11901 {
11904 "when distributing negation across "
11906 WARN_STRICT_OVERFLOW_MISC);
11912 }
11916 {
11919 "when distributing negation across "
11921 WARN_STRICT_OVERFLOW_MISC);
11927 }
11929 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11930 operation, EXACT_DIV_EXPR.
11932 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11933 At one time others generated faster code, it's not clear if they do
11934 after the last round to changes to the DIV code in expmed.c. */
11943 {
11947 WARN_STRICT_OVERFLOW_MISC);
11949 }
11957 /* X % -Y is the same as X % Y. */
11970 {
11974 WARN_STRICT_OVERFLOW_MISC);
11976 }
11978 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11979 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11983 {
11985 /* Also optimize A % (C << N) where C is a power of 2,
11986 to A & ((C << N) - 1). */
11991 {
11992 tree mask
11997 "occur when simplifying "
11999 WARN_STRICT_OVERFLOW_MISC);
12003 }
12004 }
12012 /* Since negative shift count is not well-defined,
12013 don't try to compute it in the compiler. */
12019 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12024 {
12028 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12029 being well defined. */
12031 {
12037 else
12039 }
12043 }
12045 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12046 into x & ((unsigned)-1 >> c) for unsigned types. */
12054 {
12057 tree lshift;
12058 tree arg00;
12061 {
12068 }
12069 }
12071 /* If we have a rotate of a bit operation with the rotate count and
12072 the second operand of the bit operation both constant,
12073 permute the two operations. */
12085 /* Two consecutive rotates adding up to the some integer
12086 multiple of the precision of the type can be ignored. */
12094 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12095 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12096 if the latter can be further optimized. */
12101 {
12105 arg1);
12109 arg1);
12113 }
12130 /* Note that the operands of this must be ints
12131 and their values must be 0 or 1.
12132 ("true" is a fixed value perhaps depending on the language.) */
12133 /* If first arg is constant zero, return it. */
12137 /* If either arg is constant true, drop it. */
12141 /* Preserve sequence points. */
12144 /* If second arg is constant zero, result is zero, but first arg
12145 must be evaluated. */
12148 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12149 case will be handled here. */
12153 /* !X && X is always false. */
12157 /* X && !X is always false. */
12162 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12163 means A >= Y && A != MAX, but in this case we know that
12164 A < X <= MAX. */
12168 {
12176 }
12185 /* Note that the operands of this must be ints
12186 and their values must be 0 or true.
12187 ("true" is a fixed value perhaps depending on the language.) */
12188 /* If first arg is constant true, return it. */
12192 /* If either arg is constant zero, drop it. */
12196 /* Preserve sequence points. */
12199 /* If second arg is constant true, result is true, but we must
12200 evaluate first arg. */
12203 /* Likewise for first arg, but note this only occurs here for
12204 TRUTH_OR_EXPR. */
12208 /* !X || X is always true. */
12212 /* X || !X is always true. */
12217 /* (X && !Y) || (!X && Y) is X ^ Y */
12220 {
12237 }
12246 /* If the second arg is constant zero, drop it. */
12249 /* If the second arg is constant true, this is a logical inversion. */
12251 {
12254 }
12255 /* Identical arguments cancel to zero. */
12259 /* !X ^ X is always true. */
12264 /* X ^ !X is always true. */
12280 /* bool_var != 0 becomes bool_var. */
12285 /* bool_var == 1 becomes bool_var. */
12290 /* bool_var != 1 becomes !bool_var. */
12297 /* bool_var == 0 becomes !bool_var. */
12304 /* !exp != 0 becomes !exp */
12309 /* If this is an equality comparison of the address of two non-weak,
12310 unaliased symbols neither of which are extern (since we do not
12311 have access to attributes for externs), then we know the result. */
12316 {
12324 else
12329 type);
12330 }
12332 /* Similarly for a NEGATE_EXPR. */
12336 arg1)))
12341 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12349 arg1),
12352 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12361 {
12365 val,
12369 }
12371 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12378 {
12380 code == NE_EXPR
12383 }
12385 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12390 /* If this is an EQ or NE comparison with zero and ARG0 is
12391 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12392 two operations, but the latter can be done in one less insn
12393 on machines that have only two-operand insns or on which a
12394 constant cannot be the first operand. */
12397 {
12402 {
12409 arg1);
12410 }
12413 {
12420 arg1);
12421 }
12422 }
12424 /* If this is an NE or EQ comparison of zero against the result of a
12425 signed MOD operation whose second operand is a power of 2, make
12426 the MOD operation unsigned since it is simpler and equivalent. */
12434 {
12444 }
12446 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12447 C1 is a valid shift constant, and C2 is a power of two, i.e.
12448 a single bit. */
12452 == INTEGER_CST
12455 {
12460 /* Check for a valid shift count. */
12462 {
12466 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12467 can be rewritten as (X & (C2 << C1)) != 0. */
12469 {
12474 }
12475 /* Otherwise, for signed (arithmetic) shifts,
12476 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12477 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12481 /* Otherwise, of unsigned (logical) shifts,
12482 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12483 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12484 else
12488 arg000);
12489 }
12490 }
12492 /* If we have (A & C) == C where C is a power of 2, convert this into
12493 (A & C) != 0. Similarly for NE_EXPR. */
12499 integer_zero_node));
12501 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12502 bit, then fold the expression into A < 0 or A >= 0. */
12507 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12508 Similarly for NE_EXPR. */
12512 {
12516 tree dandnotc
12519 notc);
12523 }
12525 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12526 Similarly for NE_EXPR. */
12530 {
12532 tree candnotd
12539 }
12541 /* If this is a comparison of a field, we may be able to simplify it. */
12544 /* Handle the constant case even without -O
12545 to make sure the warnings are given. */
12547 {
12551 }
12553 /* Optimize comparisons of strlen vs zero to a compare of the
12554 first character of the string vs zero. To wit,
12555 strlen(ptr) == 0 => *ptr == 0
12556 strlen(ptr) != 0 => *ptr != 0
12557 Other cases should reduce to one of these two (or a constant)
12558 due to the return value of strlen being unsigned. */
12561 {
12569 {
12574 }
12575 }
12577 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12578 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12582 {
12587 {
12589 {
12592 }
12595 }
12596 }
12598 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12604 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12609 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12616 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12624 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12625 (X & C) == 0 when C is a single bit. */
12630 {
12637 arg1));
12638 }
12640 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12641 constant C is a power of two, i.e. a single bit. */
12648 {
12652 }
12654 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12655 when is C is a power of two, i.e. a single bit. */
12662 {
12668 }
12672 {
12675 }
12677 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12685 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12688 {
12701 arg01),
12710 arg01),
12719 arg00),
12728 arg00),
12730 }
12734 {
12741 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12742 operand_equal_p guarantees no side-effects so we don't need
12743 to use omit_one_operand on Z. */
12747 arg10));
12751 arg11));
12755 arg10));
12759 arg11));
12761 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12764 {
12770 }
12771 }
12773 /* Attempt to simplify equality/inequality comparisons of complex
12774 values. Only lower the comparison if the result is known or
12775 can be simplified to a single scalar comparison. */
12780 {
12785 {
12788 }
12789 else
12790 {
12793 }
12796 {
12799 }
12800 else
12801 {
12804 }
12808 {
12810 {
12815 }
12816 else
12817 {
12822 }
12823 }
12827 {
12829 {
12834 }
12835 else
12836 {
12841 }
12842 }
12843 }
12855 /* Transform comparisons of the form X +- C CMP X. */
12862 {
12869 else
12872 /* (X - c) > X becomes false. */
12876 {
12880 "occur when assuming that (X - c) > X "
12882 WARN_STRICT_OVERFLOW_ALL);
12884 }
12886 /* Likewise (X + c) < X becomes false. */
12890 {
12894 "occur when assuming that "
12896 WARN_STRICT_OVERFLOW_ALL);
12898 }
12900 /* Convert (X - c) <= X to true. */
12905 {
12909 "occur when assuming that "
12911 WARN_STRICT_OVERFLOW_ALL);
12913 }
12915 /* Convert (X + c) >= X to true. */
12920 {
12924 "occur when assuming that "
12926 WARN_STRICT_OVERFLOW_ALL);
12928 }
12931 {
12932 /* Convert X + c > X and X - c < X to true for integers. */
12936 {
12939 "not occur when assuming that "
12941 WARN_STRICT_OVERFLOW_ALL);
12943 }
12948 {
12951 "not occur when assuming that "
12953 WARN_STRICT_OVERFLOW_ALL);
12955 }
12957 /* Convert X + c <= X and X - c >= X to false for integers. */
12961 {
12964 "not occur when assuming that "
12966 WARN_STRICT_OVERFLOW_ALL);
12968 }
12973 {
12976 "not occur when assuming that "
12978 WARN_STRICT_OVERFLOW_ALL);
12980 }
12981 }
12982 }
12984 /* Comparisons with the highest or lowest possible integer of
12985 the specified precision will have known values. */
12986 {
12992 {
12999 {
13012 /* The GE_EXPR and LT_EXPR cases above are not normally
13013 reached because of previous transformations. */
13017 }
13020 {
13027 arg1);
13033 arg0),
13034 arg1);
13037 }
13040 {
13055 }
13058 {
13065 arg1);
13071 arg0),
13072 arg1);
13075 }
13079 /* We will flip the signedness of the comparison operator
13080 associated with the mode of arg1, so the sign bit is
13081 specified by this mode. Check that arg1 is the signed
13082 max associated with this sign bit. */
13084 /* signed_type does not work on pointer types. */
13086 {
13087 /* The following case also applies to X < signed_max+1
13088 and X >= signed_max+1 because previous transformations. */
13090 {
13096 }
13097 }
13098 }
13099 }
13101 /* If we are comparing an ABS_EXPR with a constant, we can
13102 convert all the cases into explicit comparisons, but they may
13103 well not be faster than doing the ABS and one comparison.
13104 But ABS (X) <= C is a range comparison, which becomes a subtraction
13105 and a comparison, and is probably faster. */
13119 /* Convert ABS_EXPR<x> >= 0 to true. */
13126 {
13129 "when simplifying comparison of "
13131 WARN_STRICT_OVERFLOW_CONDITIONAL);
13134 arg0);
13135 }
13137 /* Convert ABS_EXPR<x> < 0 to false. */
13142 {
13145 "when simplifying comparison of "
13147 WARN_STRICT_OVERFLOW_CONDITIONAL);
13150 arg0);
13151 }
13153 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13154 and similarly for >= into !=. */
13164 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13165 otherwise Y might be >= # of bits in X's type and thus e.g.
13166 (unsigned char) (1 << Y) for Y 15 might be 0.
13167 If the cast is widening, then 1 << Y should have unsigned type,
13168 otherwise if Y is number of bits in the signed shift type minus 1,
13169 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13170 31 might be 0xffffffff80000000. */
13181 {
13187 }
13200 {
13204 }
13206 /* If the first operand is NaN, the result is constant. */
13210 {
13212 ? integer_zero_node
13215 }
13217 /* If the second operand is NaN, the result is constant. */
13221 {
13223 ? integer_zero_node
13226 }
13228 /* Simplify unordered comparison of something with itself. */
13234 && !flag_trapping_math
13238 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13239 {
13251 }
13256 /* When pedantic, a compound expression can be neither an lvalue
13257 nor an integer constant expression. */
13260 /* Don't let (0, 0) be null pointer constant. */
13266 /* An ASSERT_EXPR should never be passed to fold_binary. */
13272 }
13274 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13275 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13276 of GOTO_EXPR. */
13278 static tree
13280 {
13282 {
13289 /* ... fall through ... */
13293 }
13294 }
13296 /* Return whether the sub-tree ST contains a label which is accessible from
13297 outside the sub-tree. */
13299 static bool
13301 {
13302 return
13304 }
13306 /* Fold a ternary expression of code CODE and type TYPE with operands
13307 OP0, OP1, and OP2. Return the folded expression if folding is
13308 successful. Otherwise, return NULL_TREE. */
13310 tree
13313 {
13314 tree tem;
13321 /* If this is a commutative operation, and OP0 is a constant, move it
13322 to OP1 to reduce the number of tests below. */
13331 /* Strip any conversions that don't change the mode. This is safe
13332 for every expression, except for a comparison expression because
13333 its signedness is derived from its operands. So, in the latter
13334 case, only strip conversions that don't change the signedness.
13336 Note that this is done as an internal manipulation within the
13337 constant folder, in order to find the simplest representation of
13338 the arguments so that their form can be studied. In any cases,
13339 the appropriate type conversions should be put back in the tree
13340 that will get out of the constant folder. */
13342 {
13345 }
13348 {
13351 }
13354 {
13357 }
13360 {
13364 {
13370 }
13375 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13376 so all simple results must be passed through pedantic_non_lvalue. */
13378 {
13381 /* Only optimize constant conditions when the selected branch
13382 has the same type as the COND_EXPR. This avoids optimizing
13383 away "c ? x : throw", where the throw has a void type.
13384 Avoid throwing away that operand which contains label. */
13391 }
13393 {
13398 {
13403 {
13411 }
13415 }
13416 }
13418 /* If we have A op B ? A : C, we may be able to convert this to a
13419 simpler expression, depending on the operation and the values
13420 of B and C. Signed zeros prevent all of these transformations,
13421 for reasons given above each one.
13423 Also try swapping the arguments and inverting the conditional. */
13428 {
13432 }
13436 op2,
13439 {
13443 {
13447 }
13448 }
13450 /* If the second operand is simpler than the third, swap them
13451 since that produces better jump optimization results. */
13454 {
13456 /* See if this can be inverted. If it can't, possibly because
13457 it was a floating-point inequality comparison, don't do
13458 anything. */
13462 }
13464 /* Convert A ? 1 : 0 to simply A. */
13469 /* If we try to convert OP0 to our type, the
13470 call to fold will try to move the conversion inside
13471 a COND, which will recurse. In that case, the COND_EXPR
13472 is probably the best choice, so leave it alone. */
13476 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13477 over COND_EXPR in cases such as floating point comparisons. */
13486 arg0)));
13488 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13493 {
13494 /* sign_bit_p looks through both zero and sign extensions,
13495 but for this optimization only sign extensions are
13496 usable. */
13499 {
13502 {
13505 }
13507 }
13508 /* sign_bit_p only checks ARG1 bits within A's precision.
13509 If <sign bit of A> has wider type than A, bits outside
13510 of A's precision in <sign bit of A> need to be checked.
13511 If they are all 0, this optimization needs to be done
13512 in unsigned A's type, if they are all 1 in signed A's type,
13513 otherwise this can't be done. */
13519 {
13521 tree tem_type;
13534 {
13537 }
13539 {
13542 }
13543 else
13545 }
13548 return
13554 arg1)));
13555 }
13557 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13558 already handled above. */
13563 {
13572 }
13574 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13575 is probably obsolete because the first operand should be a
13576 truth value (that's why we have the two cases above), but let's
13577 leave it in until we can confirm this for all front-ends. */
13589 /* Disable the transformations below for vectors, since
13590 fold_binary_op_with_conditional_arg may undo them immediately,
13591 yielding an infinite loop. */
13595 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13604 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13609 {
13611 /* Only perform transformation if ARG0 is easily inverted. */
13615 ? BIT_IOR_EXPR
13618 arg1);
13619 }
13621 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13626 {
13628 /* Only perform transformation if ARG0 is easily inverted. */
13634 op2);
13635 }
13637 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13649 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13650 of fold_ternary on them. */
13660 {
13670 {
13675 {
13683 }
13685 /* Constructor elements can be subvectors. */
13688 {
13692 }
13694 /* We keep an exact subset of the constructor elements. */
13696 {
13702 {
13706 }
13714 CONSTRUCTOR_ELT
13717 }
13718 /* The bitfield references a single constructor element. */
13720 {
13725 else
13729 }
13730 }
13731 }
13733 /* A bit-field-ref that referenced the full argument can be stripped. */
13739 /* On constants we can use native encode/interpret to constant
13740 fold (nearly) all BIT_FIELD_REFs. */
13744 /* This limitation should not be necessary, we just need to
13745 round this up to mode size. */
13747 /* Need bit-shifting of the buffer to relax the following. */
13749 {
13754 /* ??? We cannot tell native_encode_expr to start at
13755 some random byte only. So limit us to a reasonable amount
13756 of work. */
13758 {
13763 {
13769 }
13770 }
13771 }
13776 /* For integers we can decompose the FMA if possible. */
13788 {
13804 {
13809 /* Make sure that the perm value is in an acceptable
13810 range. */
13819 else
13824 }
13827 {
13832 }
13837 {
13842 }
13848 {
13852 }
13857 /* Some targets are deficient and fail to expand a single
13858 argument permutation while still allowing an equivalent
13859 2-argument version. */
13863 {
13866 }
13869 {
13876 }
13880 }
13886 }
13888 /* Perform constant folding and related simplification of EXPR.
13889 The related simplifications include x*1 => x, x*0 => 0, etc.,
13890 and application of the associative law.
13891 NOP_EXPR conversions may be removed freely (as long as we
13892 are careful not to change the type of the overall expression).
13893 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13894 but we can constant-fold them if they have constant operands. */
13896 #ifdef ENABLE_FOLD_CHECKING
13897 # define fold(x) fold_1 (x)
13899 static
13900 #endif
13901 tree
13903 {
13907 tree tem;
13910 /* Return right away if a constant. */
13914 /* CALL_EXPR-like objects with variable numbers of operands are
13915 treated specially. */
13917 {
13919 {
13922 }
13924 }
13927 {
13932 {
13950 }
13951 }
13954 {
13956 {
13963 {
13968 /* Find a matching index by means of a binary search. */
13970 {
13986 else
13988 }
13989 }
13992 }
13994 /* Return a VECTOR_CST if possible. */
13996 {
14003 tree value;
14006 {
14010 {
14013 }
14014 else
14016 }
14021 }
14029 }
14031 #ifdef ENABLE_FOLD_CHECKING
14032 #undef fold
14039 /* When --enable-checking=fold, compute a digest of expr before
14040 and after actual fold call to see if fold did not accidentally
14041 change original expr. */
14043 tree
14045 {
14046 tree ret;
14066 }
14068 void
14070 {
14081 }
14083 static void
14085 {
14087 }
14089 static void
14092 {
14098 recursive_label:
14108 {
14109 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
14114 }
14121 {
14122 /* Allow these fields to be modified. */
14123 tree tmp;
14131 {
14134 }
14135 }
14146 {
14149 {
14164 }
14168 {
14181 }
14198 {
14204 }
14207 {
14209 {
14212 }
14214 }
14225 {
14228 }
14238 }
14239 }
14241 /* Helper function for outputting the checksum of a tree T. When
14242 debugging with gdb, you can "define mynext" to be "next" followed
14243 by "call debug_fold_checksum (op0)", then just trace down till the
14244 outputs differ. */
14246 DEBUG_FUNCTION void
14248 {
14263 }
14265 #endif
14267 /* Fold a unary tree expression with code CODE of type TYPE with an
14268 operand OP0. LOC is the location of the resulting expression.
14269 Return a folded expression if successful. Otherwise, return a tree
14270 expression with code CODE of type TYPE with an operand OP0. */
14272 tree
14275 {
14276 tree tem;
14277 #ifdef ENABLE_FOLD_CHECKING
14286 #endif
14292 #ifdef ENABLE_FOLD_CHECKING
14299 #endif
14301 }
14303 /* Fold a binary tree expression with code CODE of type TYPE with
14304 operands OP0 and OP1. LOC is the location of the resulting
14305 expression. Return a folded expression if successful. Otherwise,
14306 return a tree expression with code CODE of type TYPE with operands
14307 OP0 and OP1. */
14309 tree
14312 MEM_STAT_DECL)
14313 {
14314 tree tem;
14315 #ifdef ENABLE_FOLD_CHECKING
14332 #endif
14338 #ifdef ENABLE_FOLD_CHECKING
14353 #endif
14355 }
14357 /* Fold a ternary tree expression with code CODE of type TYPE with
14358 operands OP0, OP1, and OP2. Return a folded expression if
14359 successful. Otherwise, return a tree expression with code CODE of
14360 type TYPE with operands OP0, OP1, and OP2. */
14362 tree
14365 {
14366 tree tem;
14367 #ifdef ENABLE_FOLD_CHECKING
14391 #endif
14398 #ifdef ENABLE_FOLD_CHECKING
14421 #endif
14423 }
14425 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14426 arguments in ARGARRAY, and a null static chain.
14427 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14428 of type TYPE from the given operands as constructed by build_call_array. */
14430 tree
14433 {
14434 tree tem;
14435 #ifdef ENABLE_FOLD_CHECKING
14454 #endif
14460 #ifdef ENABLE_FOLD_CHECKING
14476 #endif
14478 }
14480 /* Perform constant folding and related simplification of initializer
14481 expression EXPR. These behave identically to "fold_buildN" but ignore
14482 potential run-time traps and exceptions that fold must preserve. */
14484 #define START_FOLD_INIT \
14485 int saved_signaling_nans = flag_signaling_nans;\
14486 int saved_trapping_math = flag_trapping_math;\
14487 int saved_rounding_math = flag_rounding_math;\
14488 int saved_trapv = flag_trapv;\
14489 int saved_folding_initializer = folding_initializer;\
14490 flag_signaling_nans = 0;\
14491 flag_trapping_math = 0;\
14492 flag_rounding_math = 0;\
14493 flag_trapv = 0;\
14494 folding_initializer = 1;
14496 #define END_FOLD_INIT \
14497 flag_signaling_nans = saved_signaling_nans;\
14498 flag_trapping_math = saved_trapping_math;\
14499 flag_rounding_math = saved_rounding_math;\
14500 flag_trapv = saved_trapv;\
14501 folding_initializer = saved_folding_initializer;
14503 tree
14506 {
14507 tree result;
14508 START_FOLD_INIT;
14512 END_FOLD_INIT;
14514 }
14516 tree
14519 {
14520 tree result;
14521 START_FOLD_INIT;
14525 END_FOLD_INIT;
14527 }
14529 tree
14532 {
14533 tree result;
14534 START_FOLD_INIT;
14538 END_FOLD_INIT;
14540 }
14542 #undef START_FOLD_INIT
14543 #undef END_FOLD_INIT
14545 /* Determine if first argument is a multiple of second argument. Return 0 if
14546 it is not, or we cannot easily determined it to be.
14548 An example of the sort of thing we care about (at this point; this routine
14549 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14550 fold cases do now) is discovering that
14552 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14554 is a multiple of
14556 SAVE_EXPR (J * 8)
14558 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14560 This code also handles discovering that
14562 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14564 is a multiple of 8 so we don't have to worry about dealing with a
14565 possible remainder.
14567 Note that we *look* inside a SAVE_EXPR only to determine how it was
14568 calculated; it is not safe for fold to do much of anything else with the
14569 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14570 at run time. For example, the latter example above *cannot* be implemented
14571 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14572 evaluation time of the original SAVE_EXPR is not necessarily the same at
14573 the time the new expression is evaluated. The only optimization of this
14574 sort that would be valid is changing
14576 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14578 divided by 8 to
14580 SAVE_EXPR (I) * SAVE_EXPR (J)
14582 (where the same SAVE_EXPR (J) is used in the original and the
14583 transformed version). */
14585 int
14587 {
14595 {
14597 /* Bitwise and provides a power of two multiple. If the mask is
14598 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14601 /* FALLTHRU */
14614 {
14618 /* const_binop may not detect overflow correctly,
14619 so check for it explicitly here. */
14623 size_one_node,
14624 op1)))
14627 }
14631 /* Can't handle conversions from non-integral or wider integral type. */
14637 /* .. fall through ... */
14654 SIGNED);
14658 }
14659 }
14661 /* Return true if CODE or TYPE is known to be non-negative. */
14663 static bool
14665 {
14668 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14669 have a signed:1 type (where the value is -1 and 0). */
14672 }
14674 /* Return true if (CODE OP0) is known to be non-negative. If the return
14675 value is based on the assumption that signed overflow is undefined,
14676 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14677 *STRICT_OVERFLOW_P. */
14679 bool
14682 {
14687 {
14689 /* We can't return 1 if flag_wrapv is set because
14690 ABS_EXPR<INT_MIN> = INT_MIN. */
14694 {
14697 }
14704 strict_overflow_p);
14706 CASE_CONVERT:
14707 {
14712 {
14715 strict_overflow_p);
14717 {
14721 strict_overflow_p);
14722 }
14723 }
14725 {
14728 strict_overflow_p);
14732 }
14733 }
14738 }
14740 /* We don't know sign of `t', so be conservative and return false. */
14742 }
14744 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14745 value is based on the assumption that signed overflow is undefined,
14746 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14747 *STRICT_OVERFLOW_P. */
14749 bool
14752 {
14757 {
14762 strict_overflow_p)
14764 strict_overflow_p));
14766 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14767 both unsigned and at least 2 bits shorter than the result. */
14771 {
14776 {
14780 }
14781 }
14786 {
14787 /* x * x is always non-negative for floating point x
14788 or without overflow. */
14792 {
14797 }
14798 }
14800 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14801 both unsigned and their total bits is shorter than the result. */
14805 {
14824 {
14834 }
14835 }
14841 strict_overflow_p)
14843 strict_overflow_p));
14854 strict_overflow_p)
14856 strict_overflow_p));
14863 strict_overflow_p);
14866 }
14868 /* We don't know sign of `t', so be conservative and return false. */
14870 }
14872 /* Return true if T is known to be non-negative. If the return
14873 value is based on the assumption that signed overflow is undefined,
14874 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14875 *STRICT_OVERFLOW_P. */
14877 bool
14879 {
14884 {
14896 strict_overflow_p)
14898 strict_overflow_p));
14902 }
14903 /* We don't know sign of `t', so be conservative and return false. */
14905 }
14907 /* Return true if T is known to be non-negative. If the return
14908 value is based on the assumption that signed overflow is undefined,
14909 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14910 *STRICT_OVERFLOW_P. */
14912 bool
14915 {
14918 {
14938 /* Always true. */
14942 /* sqrt(-0.0) is -0.0. */
14946 strict_overflow_p);
14983 /* True if the 1st argument is nonnegative. */
14985 strict_overflow_p);
14988 /* True if the 1st OR 2nd arguments are nonnegative. */
14990 strict_overflow_p)
14992 strict_overflow_p)));
14995 /* True if the 1st AND 2nd arguments are nonnegative. */
14997 strict_overflow_p)
14999 strict_overflow_p)));
15002 /* True if the 2nd argument is nonnegative. */
15004 strict_overflow_p);
15007 /* True if the 1st argument is nonnegative or the second
15008 argument is an even integer. */
15013 strict_overflow_p);
15016 /* True if the 1st argument is nonnegative or the second
15017 argument is an even integer valued real. */
15019 {
15020 REAL_VALUE_TYPE c;
15021 HOST_WIDE_INT n;
15026 {
15027 REAL_VALUE_TYPE cint;
15031 }
15032 }
15034 strict_overflow_p);
15038 }
15040 type);
15041 }
15043 /* Return true if T is known to be non-negative. If the return
15044 value is based on the assumption that signed overflow is undefined,
15045 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15046 *STRICT_OVERFLOW_P. */
15048 static bool
15050 {
15056 {
15058 {
15062 /* If the initializer is non-void, then it's a normal expression
15063 that will be assigned to the slot. */
15067 /* Otherwise, the initializer sets the slot in some way. One common
15068 way is an assignment statement at the end of the initializer. */
15070 {
15078 else
15080 }
15084 strict_overflow_p);
15087 }
15090 {
15096 arg0,
15097 arg1,
15098 strict_overflow_p);
15099 }
15103 strict_overflow_p);
15106 strict_overflow_p);
15109 strict_overflow_p);
15114 }
15116 /* We don't know sign of `t', so be conservative and return false. */
15118 }
15120 /* Return true if T is known to be non-negative. If the return
15121 value is based on the assumption that signed overflow is undefined,
15122 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15123 *STRICT_OVERFLOW_P. */
15125 bool
15127 {
15134 {
15141 strict_overflow_p);
15147 strict_overflow_p);
15156 }
15159 {
15167 strict_overflow_p);
15172 strict_overflow_p);
15185 }
15186 }
15188 /* Return true if `t' is known to be non-negative. Handle warnings
15189 about undefined signed overflow. */
15191 bool
15193 {
15200 "determining that expression is always "
15202 WARN_STRICT_OVERFLOW_MISC);
15204 }
15207 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15208 For floating point we further ensure that T is not denormal.
15209 Similar logic is present in nonzero_address in rtlanal.h.
15211 If the return value is based on the assumption that signed overflow
15212 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15213 change *STRICT_OVERFLOW_P. */
15215 bool
15218 {
15220 {
15223 strict_overflow_p);
15226 {
15232 strict_overflow_p));
15233 }
15238 strict_overflow_p);
15242 }
15245 }
15247 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15248 For floating point we further ensure that T is not denormal.
15249 Similar logic is present in nonzero_address in rtlanal.h.
15251 If the return value is based on the assumption that signed overflow
15252 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15253 change *STRICT_OVERFLOW_P. */
15255 bool
15257 tree type,
15258 tree op0,
15260 {
15263 {
15267 {
15268 /* With the presence of negative values it is hard
15269 to say something. */
15276 /* One of operands must be positive and the other non-negative. */
15277 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15278 overflows, on a twos-complement machine the sum of two
15279 nonnegative numbers can never be zero. */
15281 strict_overflow_p)
15283 strict_overflow_p));
15284 }
15289 {
15291 strict_overflow_p)
15293 strict_overflow_p))
15294 {
15297 }
15298 }
15307 {
15310 }
15317 {
15321 /* When both operands are nonzero, then MAX must be too. */
15323 strict_overflow_p))
15326 /* MAX where operand 0 is positive is positive. */
15328 strict_overflow_p);
15329 }
15330 /* MAX where operand 1 is positive is positive. */
15335 {
15339 }
15344 strict_overflow_p)
15346 strict_overflow_p));
15350 }
15353 }
15355 /* Return true when T is an address and is known to be nonzero.
15356 For floating point we further ensure that T is not denormal.
15357 Similar logic is present in nonzero_address in rtlanal.h.
15359 If the return value is based on the assumption that signed overflow
15360 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15361 change *STRICT_OVERFLOW_P. */
15363 bool
15365 {
15368 {
15373 {
15382 /* For objects in symbol table check if we know they are non-zero.
15383 Don't do anything for variables and functions before symtab is built;
15384 it is quite possible that they will be declared weak later. */
15386 {
15392 else
15394 }
15396 /* Function local objects are never NULL. */
15403 /* Constants are never weak. */
15408 }
15416 {
15420 }
15425 }
15427 }
15429 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15430 attempt to fold the expression to a constant without modifying TYPE,
15431 OP0 or OP1.
15433 If the expression could be simplified to a constant, then return
15434 the constant. If the expression would not be simplified to a
15435 constant, then return NULL_TREE. */
15437 tree
15439 {
15442 }
15444 /* Given the components of a unary expression CODE, TYPE and OP0,
15445 attempt to fold the expression to a constant without modifying
15446 TYPE or OP0.
15448 If the expression could be simplified to a constant, then return
15449 the constant. If the expression would not be simplified to a
15450 constant, then return NULL_TREE. */
15452 tree
15454 {
15457 }
15459 /* If EXP represents referencing an element in a constant string
15460 (either via pointer arithmetic or array indexing), return the
15461 tree representing the value accessed, otherwise return NULL. */
15463 tree
15465 {
15469 {
15471 tree index;
15472 tree string;
15477 else
15478 {
15482 /* Optimize the special-case of a zero lower bound.
15484 We convert the low_bound to sizetype to avoid some problems
15485 with constant folding. (E.g. suppose the lower bound is 1,
15486 and its mode is QI. Without the conversion,l (ARRAY
15487 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15488 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15494 }
15507 }
15509 }
15511 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15512 an integer constant, real, or fixed-point constant.
15514 TYPE is the type of the result. */
15516 static tree
15518 {
15522 {
15524 {
15531 }
15538 {
15539 FIXED_VALUE_TYPE f;
15544 /* Propagate overflow flags. */
15548 }
15552 }
15555 }
15557 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15558 an integer constant or real constant.
15560 TYPE is the type of the result. */
15562 tree
15564 {
15568 {
15570 {
15571 /* If the value is unsigned or non-negative, then the absolute value
15572 is the same as the ordinary value. */
15576 /* If the value is negative, then the absolute value is
15577 its negation. */
15578 else
15579 {
15584 }
15585 }
15591 else
15597 }
15600 }
15602 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15603 constant. TYPE is the type of the result. */
15605 static tree
15607 {
15611 }
15613 /* Given CODE, a relational operator, the target type, TYPE and two
15614 constant operands OP0 and OP1, return the result of the
15615 relational operation. If the result is not a compile time
15616 constant, then return NULL_TREE. */
15618 static tree
15620 {
15623 /* From here on, the only cases we handle are when the result is
15624 known to be a constant. */
15627 {
15631 /* Handle the cases where either operand is a NaN. */
15633 {
15635 {
15663 }
15666 }
15669 }
15672 {
15676 }
15678 /* Handle equality/inequality of complex constants. */
15680 {
15691 else
15693 }
15696 {
15703 {
15715 }
15718 }
15720 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15722 To compute GT, swap the arguments and do LT.
15723 To compute GE, do LT and invert the result.
15724 To compute LE, swap the arguments, do LT and invert the result.
15725 To compute NE, do EQ and invert the result.
15727 Therefore, the code below must handle only EQ and LT. */
15730 {
15735 }
15737 /* Note that it is safe to invert for real values here because we
15738 have already handled the one case that it matters. */
15742 {
15745 }
15747 /* Compute a result for LT or EQ if args permit;
15748 Otherwise return T. */
15750 {
15753 else
15755 }
15756 else
15762 }
15764 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15765 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15766 itself. */
15768 tree
15770 {
15771 /* If the expression does not have side effects then we don't have to wrap
15772 it with a cleanup point expression. */
15776 /* If the expression is a return, check to see if the expression inside the
15777 return has no side effects or the right hand side of the modify expression
15778 inside the return. If either don't have side effects set we don't need to
15779 wrap the expression in a cleanup point expression. Note we don't check the
15780 left hand side of the modify because it should always be a return decl. */
15782 {
15789 }
15792 }
15794 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15795 of an indirection through OP0, or NULL_TREE if no simplification is
15796 possible. */
15798 tree
15800 {
15802 tree subtype;
15810 {
15813 /* *&CONST_DECL -> to the value of the const decl. */
15816 /* *&p => p; make sure to handle *&"str"[cst] here. */
15818 {
15822 else
15824 }
15825 /* *(foo *)&fooarray => fooarray[0] */
15828 && (!in_gimple_form
15830 {
15840 }
15841 /* *(foo *)&complexfoo => __real__ complexfoo */
15845 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15848 {
15852 }
15853 }
15857 {
15863 {
15864 tree op00type;
15868 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15871 {
15883 }
15884 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15887 {
15891 }
15892 /* ((foo *)&fooarray)[1] => fooarray[1] */
15895 {
15905 }
15906 }
15907 }
15909 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15912 && (!in_gimple_form
15914 {
15915 tree type_domain;
15925 NULL_TREE);
15926 }
15929 }
15931 /* Builds an expression for an indirection through T, simplifying some
15932 cases. */
15934 tree
15936 {
15944 }
15946 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15948 tree
15950 {
15955 else
15957 }
15959 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15960 whose result is ignored. The type of the returned tree need not be
15961 the same as the original expression. */
15963 tree
15965 {
15971 {
15982 else
15988 {
16004 }
16009 }
16010 }
16012 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16014 tree
16016 {
16022 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16023 have to do anything. Only do this when we are not given a const,
16024 because in that case, this check is more expensive than just
16025 doing it. */
16027 {
16032 }
16034 /* If divisor is a power of two, simplify this to bit manipulation. */
16036 {
16038 {
16052 }
16053 else
16054 {
16055 tree t;
16061 }
16062 }
16063 else
16064 {
16069 }
16072 }
16074 /* Likewise, but round down. */
16076 tree
16078 {
16085 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16086 have to do anything. Only do this when we are not given a const,
16087 because in that case, this check is more expensive than just
16088 doing it. */
16090 {
16095 }
16097 /* If divisor is a power of two, simplify this to bit manipulation. */
16099 {
16100 tree t;
16104 }
16105 else
16106 {
16111 }
16114 }
16116 /* Returns the pointer to the base of the object addressed by EXP and
16117 extracts the information about the offset of the access, storing it
16118 to PBITPOS and POFFSET. */
16120 static tree
16123 {
16124 tree core;
16125 machine_mode mode;
16127 HOST_WIDE_INT bitsize;
16131 {
16136 }
16137 else
16138 {
16142 }
16145 }
16147 /* Returns true if addresses of E1 and E2 differ by a constant, false
16148 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16150 bool
16152 {
16166 {
16176 }
16178 {
16179 /* If only one of the offsets is non-constant, the difference cannot
16180 be a constant. */
16182 }
16183 else
16188 }
16190 /* Simplify the floating point expression EXP when the sign of the
16191 result is not significant. Return NULL_TREE if no simplification
16192 is possible. */
16194 tree
16196 {
16201 {
16237 {
16240 {
16242 /* Strip copysign function call, return the 1st argument. */
16248 /* Strip sign ops from the argument of "odd" math functions. */
16250 {
16254 }
16256 }
16257 }
16262 }
16264 }
16266 /* Return OFF converted to a pointer offset type suitable as offset for
16267 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16268 tree
16270 {
16272 }
16274 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16275 tree
16277 {
16280 }
16282 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16283 tree
16285 {
16288 }