| blob | 6d085b185895f715d99a53a9e706295aa983d52a |
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 {
3048 /* If the CALL_EXPRs call different functions, then they
3049 clearly can not be equal. */
3051 flags))
3054 {
3058 else
3062 }
3064 /* Now see if all the arguments are the same. */
3065 {
3076 /* If we get here and both argument lists are exhausted
3077 then the CALL_EXPRs are equal. */
3079 }
3082 }
3085 /* Consider __builtin_sqrt equal to sqrt. */
3093 }
3095 #undef OP_SAME
3096 #undef OP_SAME_WITH_NULL
3097 }
3098 \f
3099 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3100 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3102 When in doubt, return 0. */
3104 static int
3106 {
3118 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3119 and see if the inner values are the same. This removes any
3120 signedness comparison, which doesn't matter here. */
3127 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3128 actual comparison operand, ARG0.
3130 First throw away any conversions to wider types
3131 already present in the operands. */
3140 {
3143 /* Make sure shorter operand is extended the right way
3144 to match the longer operand. */
3150 }
3153 }
3154 \f
3155 /* See if ARG is an expression that is either a comparison or is performing
3156 arithmetic on comparisons. The comparisons must only be comparing
3157 two different values, which will be stored in *CVAL1 and *CVAL2; if
3158 they are nonzero it means that some operands have already been found.
3159 No variables may be used anywhere else in the expression except in the
3160 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3161 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3163 If this is true, return 1. Otherwise, return zero. */
3165 static int
3167 {
3171 /* We can handle some of the tcc_expression cases here. */
3181 {
3182 /* If we've already found a CVAL1 or CVAL2, this expression is
3183 two complex to handle. */
3189 }
3192 {
3215 /* First see if we can handle the first operand, then the second. For
3216 the second operand, we know *CVAL1 can't be zero. It must be that
3217 one side of the comparison is each of the values; test for the
3218 case where this isn't true by failing if the two operands
3219 are the same. */
3228 ;
3232 ;
3233 else
3237 ;
3241 ;
3242 else
3249 }
3250 }
3251 \f
3252 /* ARG is a tree that is known to contain just arithmetic operations and
3253 comparisons. Evaluate the operations in the tree substituting NEW0 for
3254 any occurrence of OLD0 as an operand of a comparison and likewise for
3255 NEW1 and OLD1. */
3257 static tree
3260 {
3265 /* We can handle some of the tcc_expression cases here. */
3273 {
3288 {
3307 }
3308 /* Fall through - ??? */
3311 {
3315 /* We need to check both for exact equality and tree equality. The
3316 former will be true if the operand has a side-effect. In that
3317 case, we know the operand occurred exactly once. */
3330 }
3334 }
3335 }
3336 \f
3337 /* Return a tree for the case when the result of an expression is RESULT
3338 converted to TYPE and OMITTED was previously an operand of the expression
3339 but is now not needed (e.g., we folded OMITTED * 0).
3341 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3342 the conversion of RESULT to TYPE. */
3344 tree
3346 {
3349 /* If the resulting operand is an empty statement, just return the omitted
3350 statement casted to void. */
3360 }
3362 /* Return a tree for the case when the result of an expression is RESULT
3363 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3364 of the expression but are now not needed.
3366 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3367 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3368 evaluated before OMITTED2. Otherwise, if neither has side effects,
3369 just do the conversion of RESULT to TYPE. */
3371 tree
3374 {
3383 }
3385 \f
3386 /* Return a simplified tree node for the truth-negation of ARG. This
3387 never alters ARG itself. We assume that ARG is an operation that
3388 returns a truth value (0 or 1).
3390 FIXME: one would think we would fold the result, but it causes
3391 problems with the dominator optimizer. */
3393 static tree
3395 {
3400 /* If this is a comparison, we can simply invert it, except for
3401 floating-point non-equality comparisons, in which case we just
3402 enclose a TRUTH_NOT_EXPR around what we have. */
3405 {
3408 && flag_trapping_math
3419 }
3422 {
3441 /* Here we can invert either operand. We invert the first operand
3442 unless the second operand is a TRUTH_NOT_EXPR in which case our
3443 result is the XOR of the first operand with the inside of the
3444 negation of the second operand. */
3449 else
3472 {
3479 /* A COND_EXPR may have a throw as one operand, which
3480 then has void type. Just leave void operands
3481 as they are. */
3487 }
3499 CASE_CONVERT:
3503 /* ... fall through ... */
3525 }
3526 }
3528 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3529 assume that ARG is an operation that returns a truth value (0 or 1
3530 for scalars, 0 or -1 for vectors). Return the folded expression if
3531 folding is successful. Otherwise, return NULL_TREE. */
3533 static tree
3535 {
3538 ? BIT_NOT_EXPR
3541 }
3543 /* Return a simplified tree node for the truth-negation of ARG. This
3544 never alters ARG itself. We assume that ARG is an operation that
3545 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3547 tree
3549 {
3555 ? BIT_NOT_EXPR
3558 }
3560 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3561 operands are another bit-wise operation with a common input. If so,
3562 distribute the bit operations to save an operation and possibly two if
3563 constants are involved. For example, convert
3564 (A | B) & (A | C) into A | (B & C)
3565 Further simplification will occur if B and C are constants.
3567 If this optimization cannot be done, 0 will be returned. */
3569 static tree
3572 {
3573 tree common;
3583 {
3587 }
3589 {
3593 }
3595 {
3599 }
3601 {
3605 }
3606 else
3614 }
3616 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3617 with code CODE. This optimization is unsafe. */
3618 static tree
3621 {
3625 /* (A / C) +- (B / C) -> (A +- B) / C. */
3635 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3640 {
3652 }
3655 }
3656 \f
3657 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3658 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3660 static tree
3663 {
3667 {
3674 }
3688 }
3690 /* Optimize a bit-field compare.
3692 There are two cases: First is a compare against a constant and the
3693 second is a comparison of two items where the fields are at the same
3694 bit position relative to the start of a chunk (byte, halfword, word)
3695 large enough to contain it. In these cases we can avoid the shift
3696 implicit in bitfield extractions.
3698 For constants, we emit a compare of the shifted constant with the
3699 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3700 compared. For two fields at the same position, we do the ANDs with the
3701 similar mask and compare the result of the ANDs.
3703 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3704 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3705 are the left and right operands of the comparison, respectively.
3707 If the optimization described above can be done, we return the resulting
3708 tree. Otherwise we return zero. */
3710 static tree
3713 {
3716 tree unsigned_type;
3722 tree mask;
3723 tree offset;
3725 /* Get all the information about the extractions being done. If the bit size
3726 if the same as the size of the underlying object, we aren't doing an
3727 extraction at all and so can do nothing. We also don't want to
3728 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3729 then will no longer be able to replace it. */
3737 {
3738 /* If this is not a constant, we can only do something if bit positions,
3739 sizes, and signedness are the same. */
3747 }
3749 /* See if we can find a mode to refer to this field. We should be able to,
3750 but fail if we can't. */
3759 /* Set signed and unsigned types of the precision of this mode for the
3760 shifts below. */
3763 /* Compute the bit position and size for the new reference and our offset
3764 within it. If the new reference is the same size as the original, we
3765 won't optimize anything, so return zero. */
3775 /* Make the mask to be used against the extracted field. */
3782 /* If not comparing with constant, just rework the comparison
3783 and return. */
3787 unsigned_type,
3790 mask),
3793 unsigned_type,
3796 mask));
3798 /* Otherwise, we are handling the constant case. See if the constant is too
3799 big for the field. Warn and return a tree of for 0 (false) if so. We do
3800 this not only for its own sake, but to avoid having to test for this
3801 error case below. If we didn't, we might generate wrong code.
3803 For unsigned fields, the constant shifted right by the field length should
3804 be all zero. For signed fields, the high-order bits should agree with
3805 the sign bit. */
3808 {
3810 {
3814 }
3815 }
3816 else
3817 {
3820 {
3824 }
3825 }
3827 /* Single-bit compares should always be against zero. */
3829 {
3832 }
3834 /* Make a new bitfield reference, shift the constant over the
3835 appropriate number of bits and mask it with the computed mask
3836 (in case this was a signed field). If we changed it, make a new one. */
3843 mask);
3848 }
3849 \f
3850 /* Subroutine for fold_truth_andor_1: decode a field reference.
3852 If EXP is a comparison reference, we return the innermost reference.
3854 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3855 set to the starting bit number.
3857 If the innermost field can be completely contained in a mode-sized
3858 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3860 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3861 otherwise it is not changed.
3863 *PUNSIGNEDP is set to the signedness of the field.
3865 *PMASK is set to the mask used. This is either contained in a
3866 BIT_AND_EXPR or derived from the width of the field.
3868 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3870 Return 0 if this is not a component reference or is one that we can't
3871 do anything with. */
3873 static tree
3878 {
3882 tree unsigned_type;
3885 /* All the optimizations using this function assume integer fields.
3886 There are problems with FP fields since the type_for_size call
3887 below can fail for, e.g., XFmode. */
3891 /* We are interested in the bare arrangement of bits, so strip everything
3892 that doesn't affect the machine mode. However, record the type of the
3893 outermost expression if it may matter below. */
3900 {
3906 }
3915 /* If the number of bits in the reference is the same as the bitsize of
3916 the outer type, then the outer type gives the signedness. Otherwise
3917 (in case of a small bitfield) the signedness is unchanged. */
3921 /* Compute the mask to access the bitfield. */
3930 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3938 }
3940 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3941 bit positions and MASK is SIGNED. */
3943 static int
3945 {
3949 /* If this function returns true when the type of the mask is
3950 UNSIGNED, then there will be errors. In particular see
3951 gcc.c-torture/execute/990326-1.c. There does not appear to be
3952 any documentation paper trail as to why this is so. But the pre
3953 wide-int worked with that restriction and it has been preserved
3954 here. */
3959 }
3961 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3962 represents the sign bit of EXP's type. If EXP represents a sign
3963 or zero extension, also test VAL against the unextended type.
3964 The return value is the (sub)expression whose sign bit is VAL,
3965 or NULL_TREE otherwise. */
3967 tree
3969 {
3971 tree t;
3973 /* Tree EXP must have an integral type. */
3978 /* Tree VAL must be an integer constant. */
3987 /* Handle extension from a narrower type. */
3993 }
3995 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3996 to be evaluated unconditionally. */
3998 static int
4000 {
4001 /* Strip any conversions that don't change the machine mode. */
4010 /* Don't regard global variables as simple. They may be
4011 allocated in ways unknown to the compiler (shared memory,
4012 #pragma weak, etc). */
4015 /* Weakrefs are not safe to be read, since they can be NULL.
4016 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4017 have DECL_WEAK flag set. */
4019 /* Loading a static variable is unduly expensive, but global
4020 registers aren't expensive. */
4022 }
4024 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4025 to be evaluated unconditionally.
4026 I addition to simple_operand_p, we assume that comparisons, conversions,
4027 and logic-not operations are simple, if their operands are simple, too. */
4029 static bool
4031 {
4051 }
4053 \f
4054 /* The following functions are subroutines to fold_range_test and allow it to
4055 try to change a logical combination of comparisons into a range test.
4057 For example, both
4058 X == 2 || X == 3 || X == 4 || X == 5
4059 and
4060 X >= 2 && X <= 5
4061 are converted to
4062 (unsigned) (X - 2) <= 3
4064 We describe each set of comparisons as being either inside or outside
4065 a range, using a variable named like IN_P, and then describe the
4066 range with a lower and upper bound. If one of the bounds is omitted,
4067 it represents either the highest or lowest value of the type.
4069 In the comments below, we represent a range by two numbers in brackets
4070 preceded by a "+" to designate being inside that range, or a "-" to
4071 designate being outside that range, so the condition can be inverted by
4072 flipping the prefix. An omitted bound is represented by a "-". For
4073 example, "- [-, 10]" means being outside the range starting at the lowest
4074 possible value and ending at 10, in other words, being greater than 10.
4075 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4076 always false.
4078 We set up things so that the missing bounds are handled in a consistent
4079 manner so neither a missing bound nor "true" and "false" need to be
4080 handled using a special case. */
4082 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4083 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4084 and UPPER1_P are nonzero if the respective argument is an upper bound
4085 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4086 must be specified for a comparison. ARG1 will be converted to ARG0's
4087 type if both are specified. */
4089 static tree
4092 {
4093 tree tem;
4097 /* If neither arg represents infinity, do the normal operation.
4098 Else, if not a comparison, return infinity. Else handle the special
4099 comparison rules. Note that most of the cases below won't occur, but
4100 are handled for consistency. */
4103 {
4108 }
4113 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4114 for neither. In real maths, we cannot assume open ended ranges are
4115 the same. But, this is computer arithmetic, where numbers are finite.
4116 We can therefore make the transformation of any unbounded range with
4117 the value Z, Z being greater than any representable number. This permits
4118 us to treat unbounded ranges as equal. */
4122 {
4143 }
4146 }
4147 \f
4148 /* Helper routine for make_range. Perform one step for it, return
4149 new expression if the loop should continue or NULL_TREE if it should
4150 stop. */
4152 tree
4156 {
4162 {
4164 /* We can only do something if the range is testing for zero. */
4173 /* We can only do something if the range is testing for zero
4174 and if the second operand is an integer constant. Note that
4175 saying something is "in" the range we make is done by
4176 complementing IN_P since it will set in the initial case of
4177 being not equal to zero; "out" is leaving it alone. */
4184 {
4205 }
4207 /* If this is an unsigned comparison, we also know that EXP is
4208 greater than or equal to zero. We base the range tests we make
4209 on that fact, so we record it here so we can parse existing
4210 range tests. We test arg0_type since often the return type
4211 of, e.g. EQ_EXPR, is boolean. */
4213 {
4217 NULL_TREE))
4222 /* If the high bound is missing, but we have a nonzero low
4223 bound, reverse the range so it goes from zero to the low bound
4224 minus 1. */
4226 {
4231 }
4232 }
4240 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4241 low and high are non-NULL, then normalize will DTRT. */
4244 {
4249 }
4251 /* (-x) IN [a,b] -> x in [-b, -a] */
4263 /* ~ X -> -X - 1 */
4272 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4273 move a constant to the other side. */
4278 /* If EXP is signed, any overflow in the computation is undefined,
4279 so we don't worry about it so long as our computations on
4280 the bounds don't overflow. For unsigned, overflow is defined
4281 and this is exactly the right thing. */
4293 normalize:
4294 /* Check for an unsigned range which has wrapped around the maximum
4295 value thus making n_high < n_low, and normalize it. */
4297 {
4303 /* If the range is of the form +/- [ x+1, x ], we won't
4304 be able to normalize it. But then, it represents the
4305 whole range or the empty set, so make it
4306 +/- [ -, - ]. */
4310 else
4312 }
4313 else
4321 CASE_CONVERT:
4339 /* If we're converting arg0 from an unsigned type, to exp,
4340 a signed type, we will be doing the comparison as unsigned.
4341 The tests above have already verified that LOW and HIGH
4342 are both positive.
4344 So we have to ensure that we will handle large unsigned
4345 values the same way that the current signed bounds treat
4346 negative values. */
4349 {
4350 tree high_positive;
4351 tree equiv_type;
4352 /* For fixed-point modes, we need to pass the saturating flag
4353 as the 2nd parameter. */
4355 equiv_type
4358 else
4359 equiv_type
4362 /* A range without an upper bound is, naturally, unbounded.
4363 Since convert would have cropped a very large value, use
4364 the max value for the destination type. */
4365 high_positive
4372 high_positive),
4375 /* If the low bound is specified, "and" the range with the
4376 range for which the original unsigned value will be
4377 positive. */
4379 {
4382 integer_zero_node),
4383 high_positive))
4387 }
4388 else
4389 {
4390 /* Otherwise, "or" the range with the range of the input
4391 that will be interpreted as negative. */
4394 integer_zero_node),
4395 high_positive))
4399 }
4400 }
4409 }
4410 }
4412 /* Given EXP, a logical expression, set the range it is testing into
4413 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4414 actually being tested. *PLOW and *PHIGH will be made of the same
4415 type as the returned expression. If EXP is not a comparison, we
4416 will most likely not be returning a useful value and range. Set
4417 *STRICT_OVERFLOW_P to true if the return value is only valid
4418 because signed overflow is undefined; otherwise, do not change
4419 *STRICT_OVERFLOW_P. */
4421 tree
4424 {
4432 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4433 and see if we can refine the range. Some of the cases below may not
4434 happen, but it doesn't seem worth worrying about this. We "continue"
4435 the outer loop when we've changed something; otherwise we "break"
4436 the switch, which will "break" the while. */
4442 {
4448 {
4456 }
4465 }
4467 /* If EXP is a constant, we can evaluate whether this is true or false. */
4469 {
4476 }
4480 }
4481 \f
4482 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4483 type, TYPE, return an expression to test if EXP is in (or out of, depending
4484 on IN_P) the range. Return 0 if the test couldn't be created. */
4486 tree
4489 {
4492 #ifdef HAVE_canonicalize_funcptr_for_compare
4493 /* Disable this optimization for function pointer expressions
4494 on targets that require function pointer canonicalization. */
4499 #endif
4502 {
4508 }
4526 {
4528 {
4532 }
4534 }
4536 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4538 {
4542 {
4544 {
4547 etype
4549 else
4552 }
4555 }
4556 }
4558 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4559 This requires wrap-around arithmetics for the type of the expression.
4560 First make sure that arithmetics in this type is valid, then make sure
4561 that it wraps around. */
4567 {
4570 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4571 for the type in question, as we rely on this here. */
4581 else
4583 }
4593 {
4595 {
4600 }
4602 }
4610 }
4611 \f
4612 /* Return the predecessor of VAL in its type, handling the infinite case. */
4614 static tree
4616 {
4622 else
4625 }
4627 /* Return the successor of VAL in its type, handling the infinite case. */
4629 static tree
4631 {
4637 else
4640 }
4642 /* Given two ranges, see if we can merge them into one. Return 1 if we
4643 can, 0 if we can't. Set the output range into the specified parameters. */
4645 bool
4648 {
4652 tree tem;
4662 /* Make range 0 be the range that starts first, or ends last if they
4663 start at the same value. Swap them if it isn't. */
4666 || (lowequal
4669 {
4673 }
4675 /* Now flag two cases, whether the ranges are disjoint or whether the
4676 second range is totally subsumed in the first. Note that the tests
4677 below are simplified by the ones above. */
4683 /* We now have four cases, depending on whether we are including or
4684 excluding the two ranges. */
4686 {
4687 /* If they don't overlap, the result is false. If the second range
4688 is a subset it is the result. Otherwise, the range is from the start
4689 of the second to the end of the first. */
4694 else
4696 }
4699 {
4700 /* If they don't overlap, the result is the first range. If they are
4701 equal, the result is false. If the second range is a subset of the
4702 first, and the ranges begin at the same place, we go from just after
4703 the end of the second range to the end of the first. If the second
4704 range is not a subset of the first, or if it is a subset and both
4705 ranges end at the same place, the range starts at the start of the
4706 first range and ends just before the second range.
4707 Otherwise, we can't describe this as a single range. */
4713 {
4718 {
4719 /* We are in the weird situation where high0 > high1 but
4720 high1 has no successor. Punt. */
4722 }
4723 }
4725 {
4730 {
4731 /* low0 < low1 but low1 has no predecessor. Punt. */
4733 }
4734 }
4735 else
4737 }
4740 {
4741 /* If they don't overlap, the result is the second range. If the second
4742 is a subset of the first, the result is false. Otherwise,
4743 the range starts just after the first range and ends at the
4744 end of the second. */
4749 else
4750 {
4755 {
4756 /* high1 > high0 but high0 has no successor. Punt. */
4758 }
4759 }
4760 }
4762 else
4763 {
4764 /* The case where we are excluding both ranges. Here the complex case
4765 is if they don't overlap. In that case, the only time we have a
4766 range is if they are adjacent. If the second is a subset of the
4767 first, the result is the first. Otherwise, the range to exclude
4768 starts at the beginning of the first range and ends at the end of the
4769 second. */
4771 {
4776 else
4777 {
4778 /* Canonicalize - [min, x] into - [-, x]. */
4781 {
4786 /* FALLTHROUGH */
4799 }
4801 /* Canonicalize - [x, max] into - [x, -]. */
4804 {
4809 /* FALLTHROUGH */
4825 }
4827 /* The ranges might be also adjacent between the maximum and
4828 minimum values of the given type. For
4829 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4830 return + [x + 1, y - 1]. */
4832 {
4839 }
4840 else
4842 }
4843 }
4846 else
4848 }
4852 }
4853 \f
4855 /* Subroutine of fold, looking inside expressions of the form
4856 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4857 of the COND_EXPR. This function is being used also to optimize
4858 A op B ? C : A, by reversing the comparison first.
4860 Return a folded expression whose code is not a COND_EXPR
4861 anymore, or NULL_TREE if no folding opportunity is found. */
4863 static tree
4866 {
4871 tree tem;
4876 /* If we have A op 0 ? A : -A, consider applying the following
4877 transformations:
4879 A == 0? A : -A same as -A
4880 A != 0? A : -A same as A
4881 A >= 0? A : -A same as abs (A)
4882 A > 0? A : -A same as abs (A)
4883 A <= 0? A : -A same as -abs (A)
4884 A < 0? A : -A same as -abs (A)
4886 None of these transformations work for modes with signed
4887 zeros. If A is +/-0, the first two transformations will
4888 change the sign of the result (from +0 to -0, or vice
4889 versa). The last four will fix the sign of the result,
4890 even though the original expressions could be positive or
4891 negative, depending on the sign of A.
4893 Note that all these transformations are correct if A is
4894 NaN, since the two alternatives (A and -A) are also NaNs. */
4901 /* In the case that A is of the form X-Y, '-A' (arg2) may
4902 have already been folded to Y-X, check for that. */
4910 {
4924 /* Fall through. */
4946 }
4948 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4949 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4950 both transformations are correct when A is NaN: A != 0
4951 is then true, and A == 0 is false. */
4955 {
4960 }
4962 /* Try some transformations of A op B ? A : B.
4964 A == B? A : B same as B
4965 A != B? A : B same as A
4966 A >= B? A : B same as max (A, B)
4967 A > B? A : B same as max (B, A)
4968 A <= B? A : B same as min (A, B)
4969 A < B? A : B same as min (B, A)
4971 As above, these transformations don't work in the presence
4972 of signed zeros. For example, if A and B are zeros of
4973 opposite sign, the first two transformations will change
4974 the sign of the result. In the last four, the original
4975 expressions give different results for (A=+0, B=-0) and
4976 (A=-0, B=+0), but the transformed expressions do not.
4978 The first two transformations are correct if either A or B
4979 is a NaN. In the first transformation, the condition will
4980 be false, and B will indeed be chosen. In the case of the
4981 second transformation, the condition A != B will be true,
4982 and A will be chosen.
4984 The conversions to max() and min() are not correct if B is
4985 a number and A is not. The conditions in the original
4986 expressions will be false, so all four give B. The min()
4987 and max() versions would give a NaN instead. */
4990 /* Avoid these transformations if the COND_EXPR may be used
4991 as an lvalue in the C++ front-end. PR c++/19199. */
4992 && (in_gimple_form
4998 {
5003 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5005 {
5009 }
5012 {
5021 /* In C++ a ?: expression can be an lvalue, so put the
5022 operand which will be used if they are equal first
5023 so that we can convert this back to the
5024 corresponding COND_EXPR. */
5026 {
5035 }
5042 {
5051 }
5066 }
5067 }
5069 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5070 we might still be able to simplify this. For example,
5071 if C1 is one less or one more than C2, this might have started
5072 out as a MIN or MAX and been transformed by this function.
5073 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5079 {
5083 /* We can replace A with C1 in this case. */
5088 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5089 MIN_EXPR, to preserve the signedness of the comparison. */
5091 OEP_ONLY_CONST)
5095 OEP_ONLY_CONST))
5096 {
5099 arg2));
5102 }
5106 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5107 as above. */
5109 OEP_ONLY_CONST)
5113 OEP_ONLY_CONST))
5114 {
5117 arg2));
5120 }
5124 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5125 MAX_EXPR, to preserve the signedness of the comparison. */
5127 OEP_ONLY_CONST)
5131 OEP_ONLY_CONST))
5132 {
5135 arg2));
5137 }
5141 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5143 OEP_ONLY_CONST)
5147 OEP_ONLY_CONST))
5148 {
5151 arg2));
5153 }
5159 }
5162 }
5165 \f
5166 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5167 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5168 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5169 false) >= 2)
5170 #endif
5172 /* EXP is some logical combination of boolean tests. See if we can
5173 merge it into some range test. Return the new tree if so. */
5175 static tree
5178 {
5194 /* If this is an OR operation, invert both sides; we will invert
5195 again at the end. */
5199 /* If both expressions are the same, if we can merge the ranges, and we
5200 can build the range test, return it or it inverted. If one of the
5201 ranges is always true or always false, consider it to be the same
5202 expression as the other. */
5210 {
5214 }
5216 /* On machines where the branch cost is expensive, if this is a
5217 short-circuited branch and the underlying object on both sides
5218 is the same, make a non-short-circuit operation. */
5224 {
5225 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5226 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5227 which cases we can't do this. */
5235 {
5244 {
5247 WARN_STRICT_OVERFLOW_COMPARISON);
5251 }
5252 }
5253 }
5256 }
5257 \f
5258 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5259 bit value. Arrange things so the extra bits will be set to zero if and
5260 only if C is signed-extended to its full width. If MASK is nonzero,
5261 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5263 static tree
5265 {
5268 tree temp;
5273 /* We work by getting just the sign bit into the low-order bit, then
5274 into the high-order bit, then sign-extend. We then XOR that value
5275 with C. */
5278 /* We must use a signed type in order to get an arithmetic right shift.
5279 However, we must also avoid introducing accidental overflows, so that
5280 a subsequent call to integer_zerop will work. Hence we must
5281 do the type conversion here. At this point, the constant is either
5282 zero or one, and the conversion to a signed type can never overflow.
5283 We could get an overflow if this conversion is done anywhere else. */
5292 /* If necessary, convert the type back to match the type of C. */
5297 }
5298 \f
5299 /* For an expression that has the form
5300 (A && B) || ~B
5301 or
5302 (A || B) && ~B,
5303 we can drop one of the inner expressions and simplify to
5304 A || ~B
5305 or
5306 A && ~B
5307 LOC is the location of the resulting expression. OP is the inner
5308 logical operation; the left-hand side in the examples above, while CMPOP
5309 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5310 removing a condition that guards another, as in
5311 (A != NULL && A->...) || A == NULL
5312 which we must not transform. If RHS_ONLY is true, only eliminate the
5313 right-most operand of the inner logical operation. */
5315 static tree
5318 {
5336 {
5339 {
5342 }
5343 }
5345 {
5348 {
5351 }
5352 }
5367 }
5369 /* Find ways of folding logical expressions of LHS and RHS:
5370 Try to merge two comparisons to the same innermost item.
5371 Look for range tests like "ch >= '0' && ch <= '9'".
5372 Look for combinations of simple terms on machines with expensive branches
5373 and evaluate the RHS unconditionally.
5375 For example, if we have p->a == 2 && p->b == 4 and we can make an
5376 object large enough to span both A and B, we can do this with a comparison
5377 against the object ANDed with the a mask.
5379 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5380 operations to do this with one comparison.
5382 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5383 function and the one above.
5385 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5386 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5388 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5389 two operands.
5391 We return the simplified tree or 0 if no optimization is possible. */
5393 static tree
5396 {
5397 /* If this is the "or" of two comparisons, we can do something if
5398 the comparisons are NE_EXPR. If this is the "and", we can do something
5399 if the comparisons are EQ_EXPR. I.e.,
5400 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5402 WANTED_CODE is this operation code. For single bit fields, we can
5403 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5404 comparison for one-bit fields. */
5424 /* Start by getting the comparison codes. Fail if anything is volatile.
5425 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5426 it were surrounded with a NE_EXPR. */
5435 {
5439 }
5442 {
5446 }
5457 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5460 {
5463 {
5468 }
5471 {
5477 }
5478 }
5483 /* If the RHS can be evaluated unconditionally and its operands are
5484 simple, it wins to evaluate the RHS unconditionally on machines
5485 with expensive branches. In this case, this isn't a comparison
5486 that can be merged. */
5493 {
5494 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5505 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5515 }
5517 /* See if the comparisons can be merged. Then get all the parameters for
5518 each side. */
5542 /* It must be true that the inner operation on the lhs of each
5543 comparison must be the same if we are to be able to do anything.
5544 Then see if we have constants. If not, the same must be true for
5545 the rhs's. */
5556 else
5559 /* If either comparison code is not correct for our logical operation,
5560 fail. However, we can convert a one-bit comparison against zero into
5561 the opposite comparison against that bit being set in the field. */
5565 {
5567 {
5568 /* Make the left operand unsigned, since we are only interested
5569 in the value of one bit. Otherwise we are doing the wrong
5570 thing below. */
5573 }
5574 else
5576 }
5578 /* This is analogous to the code for l_const above. */
5580 {
5582 {
5585 }
5586 else
5588 }
5590 /* See if we can find a mode that contains both fields being compared on
5591 the left. If we can't, fail. Otherwise, update all constants and masks
5592 to be relative to a field of that size. */
5597 volatilep);
5607 {
5610 }
5618 {
5625 {
5629 }
5630 }
5632 {
5639 {
5643 }
5644 }
5646 /* If the right sides are not constant, do the same for it. Also,
5647 disallow this optimization if a size or signedness mismatch occurs
5648 between the left and right sides. */
5650 {
5653 /* Make sure the two fields on the right
5654 correspond to the left without being swapped. */
5662 volatilep);
5672 {
5675 }
5684 /* Make a mask that corresponds to both fields being compared.
5685 Do this for both items being compared. If the operands are the
5686 same size and the bits being compared are in the same position
5687 then we can do this by masking both and comparing the masked
5688 results. */
5692 {
5704 }
5706 /* There is still another way we can do something: If both pairs of
5707 fields being compared are adjacent, we may be able to make a wider
5708 field containing them both.
5710 Note that we still must mask the lhs/rhs expressions. Furthermore,
5711 the mask must be shifted to account for the shift done by
5712 make_bit_field_ref. */
5717 {
5718 tree type;
5732 /* Convert to the smaller type before masking out unwanted bits. */
5735 {
5737 {
5741 }
5743 {
5747 }
5748 }
5757 }
5760 }
5762 /* Handle the case of comparisons with constants. If there is something in
5763 common between the masks, those bits of the constants must be the same.
5764 If not, the condition is always false. Test for this to avoid generating
5765 incorrect code below. */
5770 {
5772 {
5775 }
5776 else
5777 {
5780 }
5781 }
5783 /* Construct the expression we will return. First get the component
5784 reference we will make. Unless the mask is all ones the width of
5785 that field, perform the mask operation. Then compare with the
5786 merged constant. */
5796 }
5797 \f
5798 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5799 constant. */
5801 static tree
5804 {
5807 tree comp_const;
5808 tree minmax_const;
5810 tree inner;
5821 /* If something does not permit us to optimize, return the original tree. */
5829 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5830 and GT_EXPR, doing the rest with recursive calls using logical
5831 simplifications. */
5833 {
5835 {
5836 tree tem
5843 }
5846 return
5848 optimize_minmax_comparison
5850 optimize_minmax_comparison
5855 /* MAX (X, 0) == 0 -> X <= 0 */
5859 /* MAX (X, 0) == 5 -> X == 5 */
5863 /* MAX (X, 0) == -1 -> false */
5867 /* MIN (X, 0) == 0 -> X >= 0 */
5871 /* MIN (X, 0) == 5 -> false */
5874 else
5875 /* MIN (X, 0) == -1 -> X == -1 */
5880 /* MAX (X, 0) > 0 -> X > 0
5881 MAX (X, 0) > 5 -> X > 5 */
5885 /* MAX (X, 0) > -1 -> true */
5889 /* MIN (X, 0) > 0 -> false
5890 MIN (X, 0) > 5 -> false */
5893 else
5894 /* MIN (X, 0) > -1 -> X > -1 */
5899 }
5900 }
5901 \f
5902 /* T is an integer expression that is being multiplied, divided, or taken a
5903 modulus (CODE says which and what kind of divide or modulus) by a
5904 constant C. See if we can eliminate that operation by folding it with
5905 other operations already in T. WIDE_TYPE, if non-null, is a type that
5906 should be used for the computation if wider than our type.
5908 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5909 (X * 2) + (Y * 4). We must, however, be assured that either the original
5910 expression would not overflow or that overflow is undefined for the type
5911 in the language in question.
5913 If we return a non-null expression, it is an equivalent form of the
5914 original computation, but need not be in the original type.
5916 We set *STRICT_OVERFLOW_P to true if the return values depends on
5917 signed overflow being undefined. Otherwise we do not change
5918 *STRICT_OVERFLOW_P. */
5920 static tree
5923 {
5924 /* To avoid exponential search depth, refuse to allow recursion past
5925 three levels. Beyond that (1) it's highly unlikely that we'll find
5926 something interesting and (2) we've probably processed it before
5927 when we built the inner expression. */
5930 tree ret;
5935 depth++;
5937 depth--;
5940 }
5942 static tree
5945 {
5956 /* Don't deal with constants of zero here; they confuse the code below. */
5966 /* Note that we need not handle conditional operations here since fold
5967 already handles those cases. So just do arithmetic here. */
5969 {
5971 /* For a constant, we can always simplify if we are a multiply
5972 or (for divide and modulus) if it is a multiple of our constant. */
5980 /* If op0 is an expression ... */
5986 /* ... and has wrapping overflow, and its type is smaller
5987 than ctype, then we cannot pass through as widening. */
5992 /* ... or this is a truncation (t is narrower than op0),
5993 then we cannot pass through this narrowing. */
5996 /* ... or signedness changes for division or modulus,
5997 then we cannot pass through this conversion. */
6001 /* ... or has undefined overflow while the converted to
6002 type has not, we cannot do the operation in the inner type
6003 as that would introduce undefined overflow. */
6009 /* Pass the constant down and see if we can make a simplification. If
6010 we can, replace this expression with the inner simplification for
6011 possible later conversion to our or some other type. */
6016 code == MULT_EXPR
6018 strict_overflow_p))))
6023 /* If widening the type changes it from signed to unsigned, then we
6024 must avoid building ABS_EXPR itself as unsigned. */
6026 {
6030 {
6033 }
6035 }
6036 /* If the constant is negative, we cannot simplify this. */
6039 /* FALLTHROUGH */
6041 /* For division and modulus, type can't be unsigned, as e.g.
6042 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6043 For signed types, even with wrapping overflow, this is fine. */
6052 /* If widening the type changes the signedness, then we can't perform
6053 this optimization as that changes the result. */
6057 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6063 {
6070 }
6074 /* If the second operand is constant, this is a multiplication
6075 or floor division, by a power of two, so we can treat it that
6076 way unless the multiplier or divisor overflows. Signed
6077 left-shift overflow is implementation-defined rather than
6078 undefined in C90, so do not convert signed left shift into
6079 multiplication. */
6082 /* const_binop may not detect overflow correctly,
6083 so check for it explicitly here. */
6087 size_one_node,
6088 op1)))
6092 ctype,
6094 t1),
6099 /* See if we can eliminate the operation on both sides. If we can, we
6100 can return a new PLUS or MINUS. If we can't, the only remaining
6101 cases where we can do anything are if the second operand is a
6102 constant. */
6108 /* If not multiplication, we can only do this if both operands
6109 are divisible by c. */
6112 {
6117 }
6119 /* If this was a subtraction, negate OP1 and set it to be an addition.
6120 This simplifies the logic below. */
6122 {
6124 /* If OP1 was not easily negatable, the constant may be OP0. */
6126 {
6133 }
6134 }
6139 /* If either OP1 or C are negative, this optimization is not safe for
6140 some of the division and remainder types while for others we need
6141 to change the code. */
6143 {
6151 }
6153 /* If it's a multiply or a division/modulus operation of a multiple
6154 of our constant, do the operation and verify it doesn't overflow. */
6157 {
6160 /* We allow the constant to overflow with wrapping semantics. */
6164 }
6165 else
6168 /* If we have an unsigned type, we cannot widen the operation since it
6169 will change the result if the original computation overflowed. */
6173 /* If we were able to eliminate our operation from the first side,
6174 apply our operation to the second side and reform the PLUS. */
6178 /* The last case is if we are a multiply. In that case, we can
6179 apply the distributive law to commute the multiply and addition
6180 if the multiplication of the constants doesn't overflow
6181 and overflow is defined. With undefined overflow
6182 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6188 op1);
6193 /* We have a special case here if we are doing something like
6194 (C * 8) % 4 since we know that's zero. */
6197 /* If the multiplication can overflow we cannot optimize this. */
6201 {
6204 }
6206 /* ... fall through ... */
6210 /* If we can extract our operation from the LHS, do so and return a
6211 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6212 do something only if the second operand is a constant. */
6226 /* If these are the same operation types, we can associate them
6227 assuming no overflow. */
6229 {
6241 }
6243 /* If these operations "cancel" each other, we have the main
6244 optimizations of this pass, which occur when either constant is a
6245 multiple of the other, in which case we replace this with either an
6246 operation or CODE or TCODE.
6248 If we have an unsigned type, we cannot do this since it will change
6249 the result if the original computation overflowed. */
6256 {
6258 {
6265 }
6267 {
6274 }
6275 }
6280 }
6283 }
6284 \f
6285 /* Return a node which has the indicated constant VALUE (either 0 or
6286 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6287 and is of the indicated TYPE. */
6289 tree
6291 {
6300 else
6302 }
6305 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6306 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6307 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6308 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6309 COND is the first argument to CODE; otherwise (as in the example
6310 given here), it is the second argument. TYPE is the type of the
6311 original expression. Return NULL_TREE if no simplification is
6312 possible. */
6314 static tree
6319 {
6329 {
6333 /* If this operand throws an expression, then it does not make
6334 sense to try to perform a logical or arithmetic operation
6335 involving it. */
6340 }
6341 else
6342 {
6347 }
6352 /* This transformation is only worthwhile if we don't have to wrap ARG
6353 in a SAVE_EXPR and the operation can be simplified without recursing
6354 on at least one of the branches once its pushed inside the COND_EXPR. */
6363 {
6367 else
6369 }
6371 {
6375 else
6377 }
6379 /* Check that we have simplified at least one of the branches. */
6384 }
6386 \f
6387 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6389 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6390 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6391 ADDEND is the same as X.
6393 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6394 and finite. The problematic cases are when X is zero, and its mode
6395 has signed zeros. In the case of rounding towards -infinity,
6396 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6397 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6399 bool
6401 {
6405 /* Don't allow the fold with -fsignaling-nans. */
6409 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6413 /* In a vector or complex, we would need to check the sign of all zeros. */
6417 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6421 /* The mode has signed zeros, and we have to honor their sign.
6422 In this situation, there is only one case we can return true for.
6423 X - 0 is the same as X unless rounding towards -infinity is
6424 supported. */
6426 }
6428 /* Subroutine of fold() that checks comparisons of built-in math
6429 functions against real constants.
6431 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6432 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6433 is the type of the result and ARG0 and ARG1 are the operands of the
6434 comparison. ARG1 must be a TREE_REAL_CST.
6436 The function returns the constant folded tree if a simplification
6437 can be made, and NULL_TREE otherwise. */
6439 static tree
6443 {
6444 REAL_VALUE_TYPE c;
6447 {
6453 {
6454 /* sqrt(x) < y is always false, if y is negative. */
6458 /* sqrt(x) > y is always true, if y is negative and we
6459 don't care about NaNs, i.e. negative values of x. */
6463 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6466 }
6468 {
6469 REAL_VALUE_TYPE c2;
6475 {
6476 /* sqrt(x) > y is x == +Inf, when y is very large. */
6481 /* sqrt(x) > y is always false, when y is very large
6482 and we don't care about infinities. */
6484 }
6486 /* sqrt(x) > c is the same as x > c*c. */
6489 }
6491 {
6492 REAL_VALUE_TYPE c2;
6498 {
6499 /* sqrt(x) < y is always true, when y is a very large
6500 value and we don't care about NaNs or Infinities. */
6504 /* sqrt(x) < y is x != +Inf when y is very large and we
6505 don't care about NaNs. */
6510 /* sqrt(x) < y is x >= 0 when y is very large and we
6511 don't care about Infinities. */
6516 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6521 dconst0)),
6524 c2)));
6525 }
6527 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6532 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6537 dconst0)),
6540 c2)));
6541 }
6542 }
6545 }
6547 /* Subroutine of fold() that optimizes comparisons against Infinities,
6548 either +Inf or -Inf.
6550 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6551 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6552 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6554 The function returns the constant folded tree if a simplification
6555 can be made, and NULL_TREE otherwise. */
6557 static tree
6560 {
6561 machine_mode mode;
6562 REAL_VALUE_TYPE max;
6563 tree temp;
6568 /* For negative infinity swap the sense of the comparison. */
6574 {
6576 /* x > +Inf is always false, if with ignore sNANs. */
6582 /* x <= +Inf is always true, if we don't case about NaNs. */
6586 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6592 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6598 /* x < +Inf is always equal to x <= DBL_MAX. */
6604 /* x != +Inf is always equal to !(x > DBL_MAX). */
6616 }
6619 }
6621 /* Subroutine of fold() that optimizes comparisons of a division by
6622 a nonzero integer constant against an integer constant, i.e.
6623 X/C1 op C2.
6625 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6626 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6627 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6629 The function returns the constant folded tree if a simplification
6630 can be made, and NULL_TREE otherwise. */
6632 static tree
6635 {
6643 /* We have to do this the hard way to detect unsigned overflow.
6644 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6650 {
6655 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6659 }
6661 {
6665 {
6684 }
6685 }
6686 else
6687 {
6688 /* A negative divisor reverses the relational operators. */
6694 {
6713 }
6714 }
6717 {
6738 {
6741 }
6746 {
6749 }
6754 {
6757 }
6762 {
6765 }
6770 }
6773 }
6776 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6777 equality/inequality test, then return a simplified form of the test
6778 using a sign testing. Otherwise return NULL. TYPE is the desired
6779 result type. */
6781 static tree
6784 tree result_type)
6785 {
6786 /* If this is testing a single bit, we can optimize the test. */
6790 {
6791 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6792 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6796 /* This is only a win if casting to a signed type is cheap,
6797 i.e. when arg00's type is not a partial mode. */
6800 {
6803 result_type,
6806 }
6807 }
6810 }
6812 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6813 equality/inequality test, then return a simplified form of
6814 the test using shifts and logical operations. Otherwise return
6815 NULL. TYPE is the desired result type. */
6817 tree
6820 {
6821 /* If this is testing a single bit, we can optimize the test. */
6825 {
6834 /* First, see if we can fold the single bit test into a sign-bit
6835 test. */
6837 result_type);
6841 /* Otherwise we have (A & C) != 0 where C is a single bit,
6842 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6843 Similarly for (A & C) == 0. */
6845 /* If INNER is a right shift of a constant and it plus BITNUM does
6846 not overflow, adjust BITNUM and INNER. */
6852 {
6855 }
6857 /* If we are going to be able to omit the AND below, we must do our
6858 operations as unsigned. If we must use the AND, we have a choice.
6859 Normally unsigned is faster, but for some machines signed is. */
6860 #ifdef LOAD_EXTEND_OP
6863 #else
6865 #endif
6881 /* Put the AND last so it can combine with more things. */
6884 /* Make sure to return the proper type. */
6888 }
6890 }
6892 /* Check whether we are allowed to reorder operands arg0 and arg1,
6893 such that the evaluation of arg1 occurs before arg0. */
6895 static bool
6897 {
6904 }
6906 /* Test whether it is preferable two swap two operands, ARG0 and
6907 ARG1, for example because ARG0 is an integer constant and ARG1
6908 isn't. If REORDER is true, only recommend swapping if we can
6909 evaluate the operands in reverse order. */
6911 bool
6913 {
6931 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6932 for commutative and comparison operators. Ensuring a canonical
6933 form allows the optimizers to find additional redundancies without
6934 having to explicitly check for both orderings. */
6940 /* Put SSA_NAMEs last. */
6946 /* Put variables last. */
6953 }
6955 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6956 ARG0 is extended to a wider type. */
6958 static tree
6961 {
6963 tree arg1_unw;
6972 #ifdef HAVE_canonicalize_funcptr_for_compare
6973 /* Disable this optimization if we're casting a function pointer
6974 type on targets that require function pointer canonicalization. */
6979 #endif
6986 /* If possible, express the comparison in the shorter mode. */
7006 /* If we are comparing with the integer that does not fit into the range
7007 of the shorter type, the result is known. */
7018 {
7045 }
7048 }
7050 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7051 ARG0 just the signedness is changed. */
7053 static tree
7056 {
7057 tree arg0_inner;
7067 #ifdef HAVE_canonicalize_funcptr_for_compare
7068 /* Disable this optimization if we're casting a function pointer
7069 type on targets that require function pointer canonicalization. */
7074 #endif
7095 else
7099 }
7102 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7103 means A >= Y && A != MAX, but in this case we know that
7104 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7106 static tree
7108 {
7115 else
7124 {
7127 }
7129 {
7132 }
7133 else
7140 {
7141 /* Convert the pointer types into integer before taking the difference. */
7145 }
7146 else
7153 }
7155 /* Fold a sum or difference of at least one multiplication.
7156 Returns the folded tree or NULL if no simplification could be made. */
7158 static tree
7161 {
7165 /* (A * C) +- (B * C) -> (A+-B) * C.
7166 (A * C) +- A -> A * (C+-1).
7167 We are most concerned about the case where C is a constant,
7168 but other combinations show up during loop reduction. Since
7169 it is not difficult, try all four possibilities. */
7172 {
7175 }
7177 {
7180 }
7181 else
7182 {
7183 /* We cannot generate constant 1 for fract. */
7188 }
7190 {
7193 }
7195 {
7197 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7198 the purpose of this canonicalization. */
7202 {
7205 }
7206 else
7208 }
7209 else
7210 {
7211 /* We cannot generate constant 1 for fract. */
7216 }
7228 /* No identical multiplicands; see if we can find a common
7229 power-of-two factor in non-power-of-two multiplies. This
7230 can help in multi-dimensional array access. */
7233 {
7236 tree maybe_same;
7240 /* Move min of absolute values to int11. */
7242 {
7247 }
7248 else
7252 /* The remainder should not be a constant, otherwise we
7253 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7254 increased the number of multiplications necessary. */
7256 {
7264 }
7265 }
7275 }
7277 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7278 specified by EXPR into the buffer PTR of length LEN bytes.
7279 Return the number of bytes placed in the buffer, or zero
7280 upon failure. */
7282 static int
7284 {
7298 {
7300 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7301 number of bytes. */
7305 {
7312 else
7314 }
7315 else
7320 }
7322 }
7325 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7326 specified by EXPR into the buffer PTR of length LEN bytes.
7327 Return the number of bytes placed in the buffer, or zero
7328 upon failure. */
7330 static int
7332 {
7336 FIXED_VALUE_TYPE value;
7352 }
7355 /* Subroutine of native_encode_expr. Encode the REAL_CST
7356 specified by EXPR into the buffer PTR of length LEN bytes.
7357 Return the number of bytes placed in the buffer, or zero
7358 upon failure. */
7360 static int
7362 {
7368 /* There are always 32 bits in each long, no matter the size of
7369 the hosts long. We handle floating point representations with
7370 up to 192 bits. */
7384 {
7389 {
7396 else
7398 }
7399 else
7405 }
7407 }
7409 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7410 specified by EXPR into the buffer PTR of length LEN bytes.
7411 Return the number of bytes placed in the buffer, or zero
7412 upon failure. */
7414 static int
7416 {
7418 tree part;
7433 }
7436 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7437 specified by EXPR into the buffer PTR of length LEN bytes.
7438 Return the number of bytes placed in the buffer, or zero
7439 upon failure. */
7441 static int
7443 {
7453 {
7455 {
7458 }
7469 }
7471 }
7474 /* Subroutine of native_encode_expr. Encode the STRING_CST
7475 specified by EXPR into the buffer PTR of length LEN bytes.
7476 Return the number of bytes placed in the buffer, or zero
7477 upon failure. */
7479 static int
7481 {
7483 HOST_WIDE_INT total_bytes;
7497 {
7500 {
7503 }
7506 }
7507 else
7510 }
7513 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7514 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7515 buffer PTR of length LEN bytes. If OFF is not -1 then start
7516 the encoding at byte offset OFF and encode at most LEN bytes.
7517 Return the number of bytes placed in the buffer, or zero upon failure. */
7519 int
7521 {
7523 {
7544 }
7545 }
7548 /* Subroutine of native_interpret_expr. Interpret the contents of
7549 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7550 If the buffer cannot be interpreted, return NULL_TREE. */
7552 static tree
7554 {
7564 }
7567 /* Subroutine of native_interpret_expr. Interpret the contents of
7568 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7569 If the buffer cannot be interpreted, return NULL_TREE. */
7571 static tree
7573 {
7575 double_int result;
7576 FIXED_VALUE_TYPE fixed_value;
7586 }
7589 /* Subroutine of native_interpret_expr. Interpret the contents of
7590 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7591 If the buffer cannot be interpreted, return NULL_TREE. */
7593 static tree
7595 {
7600 /* There are always 32 bits in each long, no matter the size of
7601 the hosts long. We handle floating point representations with
7602 up to 192 bits. */
7603 REAL_VALUE_TYPE r;
7614 {
7617 {
7624 else
7626 }
7627 else
7632 }
7636 }
7639 /* Subroutine of native_interpret_expr. Interpret the contents of
7640 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7641 If the buffer cannot be interpreted, return NULL_TREE. */
7643 static tree
7645 {
7660 }
7663 /* Subroutine of native_interpret_expr. Interpret the contents of
7664 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7665 If the buffer cannot be interpreted, return NULL_TREE. */
7667 static tree
7669 {
7682 {
7687 }
7689 }
7692 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7693 the buffer PTR of length LEN as a constant of type TYPE. For
7694 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7695 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7696 return NULL_TREE. */
7698 tree
7700 {
7702 {
7724 }
7725 }
7727 /* Returns true if we can interpret the contents of a native encoding
7728 as TYPE. */
7730 static bool
7732 {
7734 {
7747 }
7748 }
7750 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7751 TYPE at compile-time. If we're unable to perform the conversion
7752 return NULL_TREE. */
7754 static tree
7756 {
7757 /* We support up to 512-bit values (for V8DFmode). */
7761 /* Check that the host and target are sane. */
7770 }
7772 /* Build an expression for the address of T. Folds away INDIRECT_REF
7773 to avoid confusing the gimplify process. */
7775 tree
7777 {
7778 /* The size of the object is not relevant when talking about its address. */
7783 {
7788 }
7798 {
7803 }
7804 else
7808 }
7810 /* Build an expression for the address of T. */
7812 tree
7814 {
7818 }
7820 /* Fold a unary expression of code CODE and type TYPE with operand
7821 OP0. Return the folded expression if folding is successful.
7822 Otherwise, return NULL_TREE. */
7824 tree
7826 {
7827 tree tem;
7828 tree arg0;
7836 {
7839 {
7840 /* Don't use STRIP_NOPS, because signedness of argument type
7841 matters. */
7843 }
7844 else
7845 {
7846 /* Strip any conversions that don't change the mode. This
7847 is safe for every expression, except for a comparison
7848 expression because its signedness is derived from its
7849 operands.
7851 Note that this is done as an internal manipulation within
7852 the constant folder, in order to find the simplest
7853 representation of the arguments so that their form can be
7854 studied. In any cases, the appropriate type conversions
7855 should be put back in the tree that will get out of the
7856 constant folder. */
7858 }
7861 {
7864 {
7868 }
7869 }
7870 }
7877 {
7884 {
7898 /* If this was a conversion, and all we did was to move into
7899 inside the COND_EXPR, bring it back out. But leave it if
7900 it is a conversion from integer to integer and the
7901 result precision is no wider than a word since such a
7902 conversion is cheap and may be optimized away by combine,
7903 while it couldn't if it were outside the COND_EXPR. Then return
7904 so we don't get into an infinite recursion loop taking the
7905 conversion out and then back in. */
7917 && (INTEGRAL_TYPE_P
7930 }
7931 }
7934 {
7940 CASE_CONVERT:
7944 {
7945 /* If we have (type) (a CMP b) and type is an integral type, return
7946 new expression involving the new type. Canonicalize
7947 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7948 non-integral type.
7949 Do not fold the result as that would not simplify further, also
7950 folding again results in recursions. */
7960 }
7962 /* Handle (T *)&A.B.C for A being of type T and B and C
7963 living at offset zero. This occurs frequently in
7964 C++ upcasting and then accessing the base. */
7968 {
7970 tree offset;
7971 machine_mode mode;
7976 /* If the reference was to a (constant) zero offset, we can use
7977 the address of the base if it has the same base type
7978 as the result type and the pointer type is unqualified. */
7985 }
7989 /* Detect assigning a bitfield. */
7991 && DECL_BIT_FIELD
7993 {
7994 /* Don't leave an assignment inside a conversion
7995 unless assigning a bitfield. */
7997 /* First do the assignment, then return converted constant. */
8002 }
8004 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8005 constants (if x has signed type, the sign bit cannot be set
8006 in c). This folds extension into the BIT_AND_EXPR.
8007 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8008 very likely don't have maximal range for their precision and this
8009 transformation effectively doesn't preserve non-maximal ranges. */
8013 {
8024 <= HOST_BITS_PER_WIDE_INT
8026 {
8030 cst &= HOST_WIDE_INT_M1U
8033 #ifdef LOAD_EXTEND_OP
8035 && !flag_syntax_only
8038 {
8042 }
8043 #endif
8044 }
8046 {
8051 }
8052 }
8054 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8055 when one of the new casts will fold away. Conservatively we assume
8056 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8063 {
8067 return fold_build_pointer_plus_loc
8069 }
8071 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8072 of the same precision, and X is an integer type not narrower than
8073 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8079 {
8085 }
8087 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8088 type of X and Y (integer types only). */
8093 {
8094 /* Be careful not to introduce new overflows. */
8095 tree mult_type;
8098 else
8102 {
8109 }
8110 }
8128 /* Convert fabs((double)float) into (double)fabsf(float). */
8131 {
8137 targ0));
8138 }
8139 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8143 /* Strip sign ops from argument. */
8145 {
8150 }
8157 {
8163 }
8169 /* Convert ~ (-A) to A - 1. */
8174 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8180 {
8181 /* Perform the negation in ARG0's type and only then convert
8182 to TYPE as to avoid introducing undefined behavior. */
8187 }
8188 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8207 /* Note that the operand of this must be an int
8208 and its values must be 0 or 1.
8209 ("true" is a fixed value perhaps depending on the language,
8210 but we don't handle values other than 1 correctly yet.) */
8220 {
8228 }
8230 {
8235 }
8237 {
8241 {
8250 }
8251 }
8258 {
8266 }
8268 {
8272 }
8274 {
8278 {
8287 }
8288 }
8292 /* Fold *&X to X if X is an lvalue. */
8294 {
8301 }
8307 }
8310 /* If the operation was a conversion do _not_ mark a resulting constant
8311 with TREE_OVERFLOW if the original constant was not. These conversions
8312 have implementation defined behavior and retaining the TREE_OVERFLOW
8313 flag here would confuse later passes such as VRP. */
8314 tree
8317 {
8326 }
8328 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8329 operands OP0 and OP1. LOC is the location of the resulting expression.
8330 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8331 Return the folded expression if folding is successful. Otherwise,
8332 return NULL_TREE. */
8333 static tree
8336 {
8337 tree tem;
8339 /* We only do these simplifications if we are optimizing. */
8343 /* Check for things like (A || B) && (A || C). We can convert this
8344 to A || (B && C). Note that either operator can be any of the four
8345 truth and/or operations and the transformation will still be
8346 valid. Also note that we only care about order for the
8347 ANDIF and ORIF operators. If B contains side effects, this
8348 might change the truth-value of A. */
8355 {
8375 /* This case if tricky because we must either have commutative
8376 operators or else A10 must not have side-effects. */
8382 a01);
8383 }
8385 /* See if we can build a range comparison. */
8391 {
8395 }
8399 {
8403 }
8405 /* Check for the possibility of merging component references. If our
8406 lhs is another similar operation, try to merge its rhs with our
8407 rhs. Then try to merge our lhs and rhs. */
8421 {
8428 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8429 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8430 We don't want to pack more than two leafs to a non-IF AND/OR
8431 expression.
8432 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8433 equal to IF-CODE, then we don't want to add right-hand operand.
8434 If the inner right-hand side of left-hand operand has
8435 side-effects, or isn't simple, then we can't add to it,
8436 as otherwise we might destroy if-sequence. */
8439 /* Needed for sequence points to handle trappings, and
8440 side-effects. */
8442 {
8444 arg1);
8446 tem);
8447 }
8448 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8449 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8452 /* Needed for sequence points to handle trappings, and
8453 side-effects. */
8455 {
8460 }
8461 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8462 into (A OR B).
8463 For sequence point consistancy, we need to check for trapping,
8464 and side-effects. */
8468 }
8471 }
8473 /* Fold a binary expression of code CODE and type TYPE with operands
8474 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8475 Return the folded expression if folding is successful. Otherwise,
8476 return NULL_TREE. */
8478 static tree
8480 {
8487 else
8490 /* MIN (MAX (a, b), b) == b. */
8495 /* MIN (MAX (b, a), b) == b. */
8501 /* MIN (a, MAX (a, b)) == a. */
8507 /* MIN (a, MAX (b, a)) == a. */
8514 }
8516 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8517 by changing CODE to reduce the magnitude of constants involved in
8518 ARG0 of the comparison.
8519 Returns a canonicalized comparison tree if a simplification was
8520 possible, otherwise returns NULL_TREE.
8521 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8522 valid if signed overflow is undefined. */
8524 static tree
8528 {
8534 /* Match A +- CST code arg1 and CST code arg1. We can change the
8535 first form only if overflow is undefined. */
8538 /* In principle pointers also have undefined overflow behavior,
8539 but that causes problems elsewhere. */
8547 /* Identify the constant in arg0 and its sign. */
8550 else
8554 /* Overflowed constants and zero will cause problems. */
8559 /* See if we can reduce the magnitude of the constant in
8560 arg0 by changing the comparison code. */
8562 {
8563 /* CST <= arg1 -> CST-1 < arg1. */
8566 /* -CST < arg1 -> -CST-1 <= arg1. */
8569 /* CST > arg1 -> CST-1 >= arg1. */
8572 /* -CST >= arg1 -> -CST-1 > arg1. */
8575 else
8577 /* arg1 code' CST' might be more canonical. */
8579 }
8580 else
8581 {
8582 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8586 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8590 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8594 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8598 else
8601 }
8603 /* Now build the constant reduced in magnitude. But not if that
8604 would produce one outside of its types range. */
8612 /* We cannot swap the comparison here as that would cause us to
8613 endlessly recurse. */
8622 /* If swapping might yield to a more canonical form, do so. */
8625 else
8627 }
8629 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8630 overflow further. Try to decrease the magnitude of constants involved
8631 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8632 and put sole constants at the second argument position.
8633 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8635 static tree
8638 {
8639 tree t;
8644 /* Try canonicalization by simplifying arg0. */
8649 {
8653 }
8655 /* Try canonicalization by simplifying arg1 using the swapped
8656 comparison. */
8664 }
8666 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8667 space. This is used to avoid issuing overflow warnings for
8668 expressions like &p->x which can not wrap. */
8670 static bool
8672 {
8679 wide_int wi_offset;
8685 else
8701 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8702 array. */
8704 {
8705 HOST_WIDE_INT base_size;
8710 }
8713 }
8715 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8716 kind INTEGER_CST. This makes sure to properly sign-extend the
8717 constant. */
8719 static HOST_WIDE_INT
8721 {
8727 }
8729 /* Subroutine of fold_binary. This routine performs all of the
8730 transformations that are common to the equality/inequality
8731 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8732 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8733 fold_binary should call fold_binary. Fold a comparison with
8734 tree code CODE and type TYPE with operands OP0 and OP1. Return
8735 the folded comparison or NULL_TREE. */
8737 static tree
8740 {
8750 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8752 && (equality_code
8759 {
8760 const enum tree_code
8767 /* If the constant operation overflowed this can be
8768 simplified as a comparison against INT_MAX/INT_MIN. */
8771 {
8775 /* Get the sign of the constant on the lhs if the
8776 operation were VARIABLE + CONST1. */
8780 /* The sign of the constant determines if we overflowed
8781 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8782 Canonicalize to the INT_MIN overflow by swapping the comparison
8783 if necessary. */
8787 /* We now can look at the canonicalized case
8788 VARIABLE + 1 CODE2 INT_MIN
8789 and decide on the result. */
8791 {
8795 return
8801 return
8806 }
8807 }
8808 else
8809 {
8812 "when changing X +- C1 cmp C2 to "
8814 WARN_STRICT_OVERFLOW_COMPARISON);
8816 }
8817 }
8819 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8821 && equality_code
8823 {
8824 /* ??? The transformation is valid for the other operators if overflow
8825 is undefined for the type, but performing it here badly interacts
8826 with the transformation in fold_cond_expr_with_comparison which
8827 attempts to synthetize ABS_EXPR. */
8831 WARN_STRICT_OVERFLOW_COMPARISON);
8834 }
8836 /* For comparisons of pointers we can decompose it to a compile time
8837 comparison of the base objects and the offsets into the object.
8838 This requires at least one operand being an ADDR_EXPR or a
8839 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8845 {
8848 machine_mode mode;
8852 /* Get base and offset for the access. Strip ADDR_EXPR for
8853 get_inner_reference, but put it back by stripping INDIRECT_REF
8854 off the base object if possible. indirect_baseN will be true
8855 if baseN is not an address but refers to the object itself. */
8858 {
8864 else
8866 }
8868 {
8872 {
8875 }
8878 {
8883 {
8886 }
8887 }
8888 }
8892 {
8898 else
8900 }
8902 {
8906 {
8909 }
8912 {
8917 {
8920 }
8921 }
8922 }
8924 /* A local variable can never be pointed to by
8925 the default SSA name of an incoming parameter. */
8927 && indirect_base0
8930 && !indirect_base1
8935 && indirect_base1
8938 && !indirect_base0
8942 {
8947 }
8948 /* If we have equivalent bases we might be able to simplify. */
8951 {
8952 /* We can fold this expression to a constant if the non-constant
8953 offset parts are equal. */
8962 {
8968 "occur when comparing P +- C1 with "
8970 WARN_STRICT_OVERFLOW_CONDITIONAL);
8973 {
8987 }
8988 }
8989 /* We can simplify the comparison to a comparison of the variable
8990 offset parts if the constant offset parts are equal.
8991 Be careful to use signed sizetype here because otherwise we
8992 mess with array offsets in the wrong way. This is possible
8993 because pointer arithmetic is restricted to retain within an
8994 object and overflow on pointer differences is undefined as of
8995 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8997 && (equality_code
9000 {
9001 /* By converting to signed sizetype we cover middle-end pointer
9002 arithmetic which operates on unsigned pointer types of size
9003 type size and ARRAY_REF offsets which are properly sign or
9004 zero extended from their type in case it is narrower than
9005 sizetype. */
9008 else
9012 else
9019 "occur when comparing P +- C1 with "
9021 WARN_STRICT_OVERFLOW_COMPARISON);
9024 }
9025 }
9026 /* For non-equal bases we can simplify if they are addresses
9027 declarations with different addresses. */
9029 /* We know that !operand_equal_p (base0, base1, 0)
9030 because the if condition was false. But make
9031 sure two decls are not the same. */
9037 /* Watch for aliases. */
9042 {
9049 }
9050 /* For equal offsets we can simplify to a comparison of the
9051 base addresses. */
9053 && (indirect_base0
9055 && (indirect_base1
9060 {
9066 }
9067 }
9069 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9070 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9071 the resulting offset is smaller in absolute value than the
9072 original one and has the same sign. */
9081 {
9086 tree cst;
9088 "occur when combining constants around "
9091 /* Put the constant on the side where it doesn't overflow and is
9092 of lower absolute value and of same sign than before. */
9099 {
9102 variable1,
9106 }
9114 {
9120 variable2);
9121 }
9122 }
9124 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9125 signed arithmetic case. That form is created by the compiler
9126 often enough for folding it to be of value. One example is in
9127 computing loop trip counts after Operator Strength Reduction. */
9134 {
9140 /* Handle unfolded multiplication by zero. */
9145 "eliminating multiplication in comparison "
9147 WARN_STRICT_OVERFLOW_COMPARISON);
9149 /* If const1 is negative we swap the sense of the comparison. */
9154 }
9161 {
9169 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9175 /* (-a) CMP (-b) -> b CMP a */
9182 {
9183 REAL_VALUE_TYPE cst;
9186 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9193 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9194 /* a CMP (-0) -> a CMP 0 */
9199 /* x != NaN is always true, other ops are always false. */
9202 {
9205 }
9207 /* Fold comparisons against infinity. */
9210 {
9214 }
9215 }
9217 /* If this is a comparison of a real constant with a PLUS_EXPR
9218 or a MINUS_EXPR of a real constant, we can convert it into a
9219 comparison with a revised real constant as long as no overflow
9220 occurs when unsafe_math_optimizations are enabled. */
9232 /* Likewise, we can simplify a comparison of a real constant with
9233 a MINUS_EXPR whose first operand is also a real constant, i.e.
9234 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9235 floating-point types only if -fassociative-math is set. */
9241 arg1))
9246 /* Fold comparisons against built-in math functions. */
9248 && flag_unsafe_math_optimizations
9250 {
9254 {
9258 }
9259 }
9260 }
9264 {
9265 /* If we are widening one operand of an integer comparison,
9266 see if the other operand is similarly being widened. Perhaps we
9267 can do the comparison in the narrower type. */
9272 /* Or if we are changing signedness. */
9276 }
9278 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9279 constant, we can simplify it. */
9284 {
9288 }
9290 /* Simplify comparison of something with itself. (For IEEE
9291 floating-point, we can only do some of these simplifications.) */
9293 {
9295 {
9310 /* For NE, we can only do this simplification if integer
9311 or we don't honor IEEE floating point NaNs. */
9315 /* ... fall through ... */
9321 }
9322 }
9324 /* If we are comparing an expression that just has comparisons
9325 of two integer values, arithmetic expressions of those comparisons,
9326 and constants, we can simplify it. There are only three cases
9327 to check: the two values can either be equal, the first can be
9328 greater, or the second can be greater. Fold the expression for
9329 those three values. Since each value must be 0 or 1, we have
9330 eight possibilities, each of which corresponds to the constant 0
9331 or 1 or one of the six possible comparisons.
9333 This handles common cases like (a > b) == 0 but also handles
9334 expressions like ((x > y) - (y > x)) > 0, which supposedly
9335 occur in macroized code. */
9338 {
9343 /* Don't handle degenerate cases here; they should already
9344 have been handled anyway. */
9353 {
9357 /* We can't just pass T to eval_subst in case cval1 or cval2
9358 was the same as ARG1. */
9360 tree high_result
9364 arg1);
9365 tree equal_result
9369 arg1);
9370 tree low_result
9374 arg1);
9376 /* All three of these results should be 0 or 1. Confirm they are.
9377 Then use those values to select the proper code to use. */
9382 {
9383 /* Make a 3-bit mask with the high-order bit being the
9384 value for `>', the next for '=', and the low for '<'. */
9388 {
9390 /* Always false. */
9411 /* Always true. */
9413 }
9416 {
9420 }
9422 }
9423 }
9424 }
9426 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9427 into a single range test. */
9435 {
9439 }
9441 /* Fold ~X op ~Y as Y op X. */
9444 {
9450 }
9452 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9455 {
9461 }
9464 }
9467 /* Subroutine of fold_binary. Optimize complex multiplications of the
9468 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9469 argument EXPR represents the expression "z" of type TYPE. */
9471 static tree
9473 {
9478 {
9481 }
9483 {
9486 }
9487 else
9488 {
9492 }
9501 }
9504 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9505 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9506 guarantees that P and N have the same least significant log2(M) bits.
9507 N is not otherwise constrained. In particular, N is not normalized to
9508 0 <= N < M as is common. In general, the precise value of P is unknown.
9509 M is chosen as large as possible such that constant N can be determined.
9511 Returns M and sets *RESIDUE to N.
9513 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9514 account. This is not always possible due to PR 35705.
9515 */
9517 static unsigned HOST_WIDE_INT
9520 {
9527 {
9532 }
9534 {
9542 allow_func_align);
9548 {
9551 }
9553 {
9556 {
9559 /* Compute the greatest power-of-2 divisor of op1. */
9563 /* If align is non-zero and less than *modulus, replace
9564 *modulus with align., If align is 0, then either op1 is 0
9565 or the greatest power-of-2 divisor of op1 doesn't fit in an
9566 unsigned HOST_WIDE_INT. In either case, no additional
9567 constraint is imposed. */
9572 }
9573 }
9574 }
9576 /* If we get here, we were unable to determine anything useful about the
9577 expression. */
9579 }
9581 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9582 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9584 static bool
9586 {
9590 {
9593 }
9595 {
9601 else
9603 }
9604 else
9610 }
9612 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9613 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9614 NULL_TREE otherwise. */
9616 static tree
9618 {
9635 {
9639 }
9642 {
9648 }
9649 else
9651 }
9653 /* Try to fold a pointer difference of type TYPE two address expressions of
9654 array references AREF0 and AREF1 using location LOC. Return a
9655 simplified expression for the difference or NULL_TREE. */
9657 static tree
9660 {
9665 /* If the bases are array references as well, recurse. If the bases
9666 are pointer indirections compute the difference of the pointers.
9667 If the bases are equal, we are set. */
9670 && (base_offset
9678 {
9684 base_offset,
9687 }
9689 }
9691 /* If the real or vector real constant CST of type TYPE has an exact
9692 inverse, return it, else return NULL. */
9694 tree
9696 {
9697 REAL_VALUE_TYPE r;
9699 machine_mode mode;
9703 {
9719 {
9724 }
9730 }
9731 }
9733 /* Mask out the tz least significant bits of X of type TYPE where
9734 tz is the number of trailing zeroes in Y. */
9735 static wide_int
9737 {
9742 }
9744 /* Return true when T is an address and is known to be nonzero.
9745 For floating point we further ensure that T is not denormal.
9746 Similar logic is present in nonzero_address in rtlanal.h.
9748 If the return value is based on the assumption that signed overflow
9749 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9750 change *STRICT_OVERFLOW_P. */
9752 static bool
9754 {
9758 /* Doing something useful for floating point would need more work. */
9764 {
9767 strict_overflow_p);
9773 strict_overflow_p);
9781 }
9784 {
9787 strict_overflow_p);
9795 strict_overflow_p);
9810 strict_overflow_p);
9814 strict_overflow_p);
9817 {
9829 }
9833 }
9835 }
9837 /* Return true when T is an address and is known to be nonzero.
9838 Handle warnings about undefined signed overflow. */
9840 static bool
9842 {
9849 "determining that expression is always "
9851 WARN_STRICT_OVERFLOW_MISC);
9853 }
9855 /* Fold a binary expression of code CODE and type TYPE with operands
9856 OP0 and OP1. LOC is the location of the resulting expression.
9857 Return the folded expression if folding is successful. Otherwise,
9858 return NULL_TREE. */
9860 tree
9863 {
9878 /* Strip any conversions that don't change the mode. This is
9879 safe for every expression, except for a comparison expression
9880 because its signedness is derived from its operands. So, in
9881 the latter case, only strip conversions that don't change the
9882 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9883 preserved.
9885 Note that this is done as an internal manipulation within the
9886 constant folder, in order to find the simplest representation
9887 of the arguments so that their form can be studied. In any
9888 cases, the appropriate type conversions should be put back in
9889 the tree that will get out of the constant folder. */
9892 {
9895 }
9896 else
9897 {
9900 }
9902 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9903 constant but we can't do arithmetic on them. */
9905 {
9908 {
9912 }
9913 }
9915 /* If this is a commutative operation, and ARG0 is a constant, move it
9916 to ARG1 to reduce the number of tests below. */
9921 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9922 to ARG1 to reduce the number of tests below. */
9931 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9933 First check for cases where an arithmetic operation is applied to a
9934 compound, conditional, or comparison operation. Push the arithmetic
9935 operation inside the compound or conditional to see if any folding
9936 can then be done. Convert comparison to conditional for this purpose.
9937 The also optimizes non-constant cases that used to be done in
9938 expand_expr.
9940 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9941 one of the operands is a comparison and the other is a comparison, a
9942 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9943 code below would make the expression more complex. Change it to a
9944 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9945 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9958 {
9962 boolean_type_node,
9970 }
9974 {
9976 {
9981 tem);
9982 }
9985 {
9990 tem);
9991 }
9996 {
10002 }
10007 {
10013 }
10014 }
10017 {
10019 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10022 {
10028 }
10030 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10033 {
10034 tree base;
10035 HOST_WIDE_INT coffset;
10044 }
10049 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10055 arg1),
10057 arg0)));
10063 {
10064 /* X + (X / CST) * -CST is X % CST. */
10069 {
10078 cst0));
10079 }
10080 }
10082 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10083 one. Make sure the type is not saturating and has the signedness of
10084 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10085 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10092 {
10096 }
10099 {
10100 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10101 with a constant, and the two constants have no bits in common,
10102 we should treat this as a BIT_IOR_EXPR since this may produce more
10103 simplifications. */
10110 {
10113 }
10115 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10116 (plus (plus (mult) (mult)) (foo)) so that we can
10117 take advantage of the factoring cases below. */
10126 {
10132 else
10145 parg0),
10147 marg)),
10151 return
10157 parg1)));
10158 }
10159 }
10160 else
10161 {
10162 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10163 to __complex__ ( x, y ). This is not the same for SNaNs or
10164 if signed zeros are involved. */
10168 {
10175 {
10179 {
10185 }
10187 {
10193 }
10194 }
10195 }
10203 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10204 We associate floats only if the user has specified
10205 -fassociative-math. */
10209 {
10214 {
10215 tree tree0;
10218 }
10219 }
10220 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10221 We associate floats only if the user has specified
10222 -fassociative-math. */
10226 {
10231 {
10232 tree tree0;
10235 }
10236 }
10237 }
10239 bit_rotate:
10240 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10241 is a rotate of A by C1 bits. */
10242 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10243 is a rotate of A by B bits. */
10244 {
10246 tree rtype;
10255 /* Only create rotates in complete modes. Other cases are not
10256 expanded properly. */
10259 {
10273 {
10277 code0 == LSHIFT_EXPR
10281 }
10283 {
10291 element_precision
10295 return
10298 ? LROTATE_EXPR
10303 }
10305 {
10313 element_precision
10317 return fold_convert_loc
10320 ? LROTATE_EXPR
10324 }
10325 }
10326 }
10328 associate:
10329 /* In most languages, can't associate operations on floats through
10330 parentheses. Rather than remember where the parentheses were, we
10331 don't associate floats at all, unless the user has specified
10332 -fassociative-math.
10333 And, we need to make sure type is not saturating. */
10337 {
10343 /* Split both trees into variables, constants, and literals. Then
10344 associate each group together, the constants with literals,
10345 then the result with variables. This increases the chances of
10346 literals being recombined later and of generating relocatable
10347 expressions for the sum of a constant and literal. */
10352 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10356 /* With undefined overflow prefer doing association in a type
10357 which wraps on overflow, if that is one of the operand types. */
10360 {
10368 }
10370 /* With undefined overflow we can only associate constants with one
10371 variable, and constants whose association doesn't overflow. */
10374 {
10376 {
10394 /* The only case we can still associate with two variables
10395 is if they are the same, modulo negation and bit-pattern
10396 preserving conversions. */
10399 }
10400 }
10402 /* Only do something if we found more than two objects. Otherwise,
10403 nothing has changed and we risk infinite recursion. */
10409 {
10421 /* Preserve the MINUS_EXPR if the negative part of the literal is
10422 greater than the positive part. Otherwise, the multiplicative
10423 folding code (i.e extract_muldiv) may be fooled in case
10424 unsigned constants are subtracted, like in the following
10425 example: ((X*2 + 4) - 8U)/2. */
10427 {
10431 {
10435 }
10436 else
10437 {
10441 }
10442 }
10444 /* Don't introduce overflows through reassociation. */
10451 {
10453 return
10457 else
10458 {
10461 return
10465 }
10466 }
10469 return
10472 }
10473 }
10478 /* Pointer simplifications for subtraction, simple reassociations. */
10480 {
10481 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10484 {
10494 }
10495 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10497 {
10504 }
10505 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10506 simplifies. */
10508 {
10515 arg10);
10518 }
10519 }
10520 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10530 /* X - (X / Y) * Y is X % Y. */
10538 return
10544 {
10545 /* Fold A - (A & B) into ~B & A. */
10548 {
10550 {
10557 }
10559 {
10566 }
10567 }
10569 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10570 any power of 2 minus 1. */
10575 {
10581 {
10585 }
10586 }
10587 }
10589 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10590 __complex__ ( x, -y ). This is not the same for SNaNs or if
10591 signed zeros are involved. */
10595 {
10602 {
10606 {
10608 arg1r ? arg1r
10613 }
10615 {
10619 arg1i ? arg1i
10622 }
10623 }
10624 }
10626 /* A - B -> A + (-B) if B is easily negatable. */
10630 /* Avoid this transformation if B is a positive REAL_CST. */
10639 /* Try folding difference of addresses. */
10640 {
10641 HOST_WIDE_INT diff;
10647 }
10649 /* Fold &a[i] - &a[j] to i-j. */
10654 {
10660 }
10663 && flag_unsafe_math_optimizations
10669 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10670 one. Make sure the type is not saturating and has the signedness of
10671 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10672 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10679 {
10683 }
10688 /* (-A) * (-B) -> A * B */
10703 {
10704 /* Transform x * -C into -x * C if x is easily negatable. */
10713 tem);
10715 /* (a * (1 << b)) is (a << b) */
10725 /* (A + A) * C -> A * 2 * C */
10737 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10738 sign-changing only. */
10748 {
10751 "occur when simplifying "
10753 WARN_STRICT_OVERFLOW_MISC);
10755 }
10757 /* Optimize z * conj(z) for integer complex numbers. */
10764 }
10765 else
10766 {
10767 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10768 the result for floating point types due to rounding so it is applied
10769 only if -fassociative-math was specify. */
10774 {
10776 arg1);
10780 }
10782 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10784 {
10787 {
10790 }
10791 }
10793 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10794 This is not the same for NaNs or if signed zeros are
10795 involved. */
10801 {
10804 return
10810 return
10815 }
10817 /* Optimize z * conj(z) for floating point complex numbers.
10818 Guarded by flag_unsafe_math_optimizations as non-finite
10819 imaginary components don't produce scalar results. */
10830 {
10834 /* Optimizations of root(...)*root(...). */
10836 {
10841 /* Optimize sqrt(x)*sqrt(x) as x. */
10847 /* Optimize root(x)*root(y) as root(x*y). */
10851 }
10853 /* Optimize expN(x)*expN(y) as expN(x+y). */
10855 {
10861 }
10863 /* Optimizations of pow(...)*pow(...). */
10867 {
10873 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10875 {
10880 }
10882 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10884 {
10889 }
10890 }
10892 /* Optimize tan(x)*cos(x) as sin(x). */
10901 {
10907 }
10909 /* Optimize x*pow(x,c) as pow(x,c+1). */
10913 {
10919 {
10921 REAL_VALUE_TYPE c;
10922 tree arg;
10928 }
10929 }
10931 /* Optimize pow(x,c)*x as pow(x,c+1). */
10935 {
10941 {
10943 REAL_VALUE_TYPE c;
10944 tree arg;
10950 }
10951 }
10953 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10955 && optimize
10957 {
10961 {
10964 }
10965 }
10966 }
10967 }
10971 bit_ior:
10972 /* ~X | X is -1. */
10975 {
10979 }
10981 /* X | ~X is -1. */
10984 {
10988 }
10990 /* Canonicalize (X & C1) | C2. */
10994 {
10999 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11007 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11012 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11013 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11014 mode which allows further optimizations. */
11019 {
11023 {
11026 }
11027 }
11034 c3)),
11035 arg1);
11036 }
11038 /* (X & ~Y) | (~X & Y) is X ^ Y */
11041 {
11058 }
11064 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11066 This results in more efficient code for machines without a NAND
11067 instruction. Combine will canonicalize to the first form
11068 which will allow use of NAND instructions provided by the
11069 backend if they exist. */
11072 {
11073 return
11080 }
11082 /* See if this can be simplified into a rotate first. If that
11083 is unsuccessful continue in the association code. */
11087 /* ~X ^ X is -1. */
11090 {
11094 }
11096 /* X ^ ~X is -1. */
11099 {
11103 }
11105 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11106 with a constant, and the two constants have no bits in common,
11107 we should treat this as a BIT_IOR_EXPR since this may produce more
11108 simplifications. */
11115 {
11118 }
11120 /* (X | Y) ^ X -> Y & ~ X*/
11123 {
11126 arg1);
11131 }
11133 /* (Y | X) ^ X -> Y & ~ X*/
11136 {
11139 arg1);
11144 }
11146 /* X ^ (X | Y) -> Y & ~ X*/
11149 {
11152 arg0);
11157 }
11159 /* X ^ (Y | X) -> Y & ~ X*/
11162 {
11165 arg0);
11170 }
11172 /* Convert ~X ^ ~Y to X ^ Y. */
11181 /* Convert ~X ^ C to X ^ ~C. */
11189 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11197 /* Fold (X & Y) ^ Y as ~X & Y. */
11200 {
11205 }
11206 /* Fold (X & Y) ^ X as ~Y & X. */
11210 {
11215 }
11216 /* Fold X ^ (X & Y) as X & ~Y. */
11219 {
11224 }
11225 /* Fold X ^ (Y & X) as ~Y & X. */
11229 {
11234 }
11236 /* See if this can be simplified into a rotate first. If that
11237 is unsuccessful continue in the association code. */
11241 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11249 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11257 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11262 {
11263 tree tem2;
11270 }
11271 /* Fold ~X & 1 as (X & 1) == 0. */
11275 {
11276 tree tem2;
11283 }
11284 /* Fold !X & 1 as X == 0. */
11287 {
11291 }
11293 /* Fold (X ^ Y) & Y as ~X & Y. */
11296 {
11301 }
11302 /* Fold (X ^ Y) & X as ~Y & X. */
11306 {
11311 }
11312 /* Fold X & (X ^ Y) as X & ~Y. */
11315 {
11320 }
11321 /* Fold X & (Y ^ X) as ~Y & X. */
11325 {
11330 }
11332 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11333 multiple of 1 << CST. */
11335 {
11342 }
11344 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11345 bits from CST2. */
11349 {
11357 {
11358 /* Avoid the transform if arg1 is a mask of some
11359 mode which allows further optimizations. */
11366 }
11367 }
11369 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11370 ((A & N) + B) & M -> (A + B) & M
11371 Similarly if (N & M) == 0,
11372 ((A | N) + B) & M -> (A + B) & M
11373 and for - instead of + (or unary - instead of +)
11374 and/or ^ instead of |.
11375 If B is constant and (B & M) == 0, fold into A & M. */
11377 {
11386 {
11389 wide_int cst0;
11391 /* Now we know that arg0 is (C + D) or (C - D) or
11392 -C and arg1 (M) is == (1LL << cst) - 1.
11393 Store C into PMOP[0] and D into PMOP[1]. */
11397 {
11400 }
11407 {
11417 {
11420 }
11423 /* If C or D is of the form (A & N) where
11424 (N & M) == M, or of the form (A | N) or
11425 (A ^ N) where (N & M) == 0, replace it with A. */
11429 /* If C or D is a N where (N & M) == 0, it can be
11430 omitted (assumed 0). */
11438 }
11440 /* Only build anything new if we optimized one or both arguments
11441 above. */
11445 {
11448 {
11449 /* Perform the operations in a type that has defined
11450 overflow behavior. */
11456 }
11461 {
11469 else
11471 }
11474 else
11477 /* TEM is now the new binary +, - or unary - replacement. */
11481 }
11482 }
11483 }
11488 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11491 {
11496 return
11498 }
11500 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11502 This results in more efficient code for machines without a NOR
11503 instruction. Combine will canonicalize to the first form
11504 which will allow use of NOR instructions provided by the
11505 backend if they exist. */
11508 {
11515 }
11517 /* If arg0 is derived from the address of an object or function, we may
11518 be able to fold this expression using the object or function's
11519 alignment. */
11521 {
11528 /* This works because modulus is a power of 2. If this weren't the
11529 case, we'd have to replace it by its greatest power-of-2
11530 divisor: modulus & -modulus. */
11533 }
11535 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11536 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11537 if the new mask might be further optimized. */
11546 {
11557 {
11560 /* See if more bits can be proven as zero because of
11561 zero extension. */
11564 {
11569 {
11571 /* See if we can shorten the right shift. */
11574 /* Otherwise X >> C1 is all zeros, so we'll optimize
11575 it into (X, 0) later on by making sure zerobits
11576 is all ones. */
11577 }
11578 }
11581 {
11584 }
11585 /* For arithmetic shift if sign bit could be set, zerobits
11586 can contain actually sign bits, so no transformation is
11587 possible, unless MASK masks them all away. In that
11588 case the shift needs to be converted into logical shift. */
11591 {
11594 else
11596 }
11597 }
11599 /* ((X << 16) & 0xff00) is (X, 0). */
11606 {
11607 /* Only do the transformation if NEWMASK is some integer
11608 mode's mask. */
11615 {
11616 tree newmaskt;
11619 {
11625 }
11626 else
11631 }
11632 }
11633 }
11638 /* Don't touch a floating-point divide by zero unless the mode
11639 of the constant can represent infinity. */
11645 /* (-A) / (-B) -> A / B */
11655 /* Convert A/B/C to A/(B*C). */
11662 /* Convert A/(B/C) to (A/B)*C. */
11670 /* Convert C1/(X*C2) into (C1/C2)/X. */
11675 {
11681 }
11684 {
11688 /* Optimize sin(x)/cos(x) as tan(x). */
11694 {
11699 }
11701 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11707 {
11711 {
11716 }
11717 }
11719 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11720 NaNs or Infinities. */
11724 {
11731 {
11736 }
11737 }
11739 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11740 NaNs or Infinities. */
11744 {
11751 {
11755 {
11759 tmp);
11760 }
11761 }
11762 }
11764 /* Optimize pow(x,c)/x as pow(x,c-1). */
11768 {
11774 {
11776 REAL_VALUE_TYPE c;
11777 tree arg;
11783 }
11784 }
11786 /* Optimize a/root(b/c) into a*root(c/b). */
11788 {
11792 {
11801 }
11802 }
11804 /* Optimize x/expN(y) into x*expN(-y). */
11806 {
11813 }
11815 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11819 {
11827 }
11828 }
11832 /* Optimize (X & (-A)) / A where A is a power of 2,
11833 to X >> log2(A) */
11837 {
11845 }
11846 }
11848 /* Fall through */
11851 /* Simplify A / (B << N) where A and B are positive and B is
11852 a power of 2, to A >> (N + log2(B)). */
11857 {
11860 {
11868 WARN_STRICT_OVERFLOW_MISC);
11874 }
11875 }
11877 /* Fall through */
11885 /* Convert -A / -B to A / B when the type is signed and overflow is
11886 undefined. */
11890 {
11893 "when distributing negation across "
11895 WARN_STRICT_OVERFLOW_MISC);
11901 }
11905 {
11908 "when distributing negation across "
11910 WARN_STRICT_OVERFLOW_MISC);
11916 }
11918 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11919 operation, EXACT_DIV_EXPR.
11921 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11922 At one time others generated faster code, it's not clear if they do
11923 after the last round to changes to the DIV code in expmed.c. */
11932 {
11936 WARN_STRICT_OVERFLOW_MISC);
11938 }
11946 /* X % -Y is the same as X % Y. */
11959 {
11963 WARN_STRICT_OVERFLOW_MISC);
11965 }
11967 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11968 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11972 {
11974 /* Also optimize A % (C << N) where C is a power of 2,
11975 to A & ((C << N) - 1). */
11980 {
11981 tree mask
11986 "occur when simplifying "
11988 WARN_STRICT_OVERFLOW_MISC);
11992 }
11993 }
12001 /* Since negative shift count is not well-defined,
12002 don't try to compute it in the compiler. */
12008 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12013 {
12017 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12018 being well defined. */
12020 {
12026 else
12028 }
12032 }
12034 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12035 into x & ((unsigned)-1 >> c) for unsigned types. */
12043 {
12046 tree lshift;
12047 tree arg00;
12050 {
12057 }
12058 }
12060 /* If we have a rotate of a bit operation with the rotate count and
12061 the second operand of the bit operation both constant,
12062 permute the two operations. */
12074 /* Two consecutive rotates adding up to the some integer
12075 multiple of the precision of the type can be ignored. */
12083 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12084 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12085 if the latter can be further optimized. */
12090 {
12094 arg1);
12098 arg1);
12102 }
12119 /* Note that the operands of this must be ints
12120 and their values must be 0 or 1.
12121 ("true" is a fixed value perhaps depending on the language.) */
12122 /* If first arg is constant zero, return it. */
12126 /* If either arg is constant true, drop it. */
12130 /* Preserve sequence points. */
12133 /* If second arg is constant zero, result is zero, but first arg
12134 must be evaluated. */
12137 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12138 case will be handled here. */
12142 /* !X && X is always false. */
12146 /* X && !X is always false. */
12151 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12152 means A >= Y && A != MAX, but in this case we know that
12153 A < X <= MAX. */
12157 {
12165 }
12174 /* Note that the operands of this must be ints
12175 and their values must be 0 or true.
12176 ("true" is a fixed value perhaps depending on the language.) */
12177 /* If first arg is constant true, return it. */
12181 /* If either arg is constant zero, drop it. */
12185 /* Preserve sequence points. */
12188 /* If second arg is constant true, result is true, but we must
12189 evaluate first arg. */
12192 /* Likewise for first arg, but note this only occurs here for
12193 TRUTH_OR_EXPR. */
12197 /* !X || X is always true. */
12201 /* X || !X is always true. */
12206 /* (X && !Y) || (!X && Y) is X ^ Y */
12209 {
12226 }
12235 /* If the second arg is constant zero, drop it. */
12238 /* If the second arg is constant true, this is a logical inversion. */
12240 {
12243 }
12244 /* Identical arguments cancel to zero. */
12248 /* !X ^ X is always true. */
12253 /* X ^ !X is always true. */
12269 /* bool_var != 0 becomes bool_var. */
12274 /* bool_var == 1 becomes bool_var. */
12279 /* bool_var != 1 becomes !bool_var. */
12286 /* bool_var == 0 becomes !bool_var. */
12293 /* !exp != 0 becomes !exp */
12298 /* If this is an equality comparison of the address of two non-weak,
12299 unaliased symbols neither of which are extern (since we do not
12300 have access to attributes for externs), then we know the result. */
12305 {
12313 else
12318 type);
12319 }
12321 /* Similarly for a NEGATE_EXPR. */
12325 arg1)))
12330 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12338 arg1),
12341 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12350 {
12354 val,
12358 }
12360 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12367 {
12369 code == NE_EXPR
12372 }
12374 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12379 /* If this is an EQ or NE comparison with zero and ARG0 is
12380 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12381 two operations, but the latter can be done in one less insn
12382 on machines that have only two-operand insns or on which a
12383 constant cannot be the first operand. */
12386 {
12391 {
12398 arg1);
12399 }
12402 {
12409 arg1);
12410 }
12411 }
12413 /* If this is an NE or EQ comparison of zero against the result of a
12414 signed MOD operation whose second operand is a power of 2, make
12415 the MOD operation unsigned since it is simpler and equivalent. */
12423 {
12433 }
12435 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12436 C1 is a valid shift constant, and C2 is a power of two, i.e.
12437 a single bit. */
12441 == INTEGER_CST
12444 {
12449 /* Check for a valid shift count. */
12451 {
12455 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12456 can be rewritten as (X & (C2 << C1)) != 0. */
12458 {
12463 }
12464 /* Otherwise, for signed (arithmetic) shifts,
12465 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12466 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12470 /* Otherwise, of unsigned (logical) shifts,
12471 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12472 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12473 else
12477 arg000);
12478 }
12479 }
12481 /* If we have (A & C) == C where C is a power of 2, convert this into
12482 (A & C) != 0. Similarly for NE_EXPR. */
12488 integer_zero_node));
12490 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12491 bit, then fold the expression into A < 0 or A >= 0. */
12496 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12497 Similarly for NE_EXPR. */
12501 {
12505 tree dandnotc
12508 notc);
12512 }
12514 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12515 Similarly for NE_EXPR. */
12519 {
12521 tree candnotd
12528 }
12530 /* If this is a comparison of a field, we may be able to simplify it. */
12533 /* Handle the constant case even without -O
12534 to make sure the warnings are given. */
12536 {
12540 }
12542 /* Optimize comparisons of strlen vs zero to a compare of the
12543 first character of the string vs zero. To wit,
12544 strlen(ptr) == 0 => *ptr == 0
12545 strlen(ptr) != 0 => *ptr != 0
12546 Other cases should reduce to one of these two (or a constant)
12547 due to the return value of strlen being unsigned. */
12550 {
12558 {
12563 }
12564 }
12566 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12567 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12571 {
12576 {
12578 {
12581 }
12584 }
12585 }
12587 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12593 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12598 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12605 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12613 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12614 (X & C) == 0 when C is a single bit. */
12619 {
12626 arg1));
12627 }
12629 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12630 constant C is a power of two, i.e. a single bit. */
12637 {
12641 }
12643 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12644 when is C is a power of two, i.e. a single bit. */
12651 {
12657 }
12661 {
12664 }
12666 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12674 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12677 {
12690 arg01),
12699 arg01),
12708 arg00),
12717 arg00),
12719 }
12723 {
12730 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12731 operand_equal_p guarantees no side-effects so we don't need
12732 to use omit_one_operand on Z. */
12736 arg10));
12740 arg11));
12744 arg10));
12748 arg11));
12750 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12753 {
12759 }
12760 }
12762 /* Attempt to simplify equality/inequality comparisons of complex
12763 values. Only lower the comparison if the result is known or
12764 can be simplified to a single scalar comparison. */
12769 {
12774 {
12777 }
12778 else
12779 {
12782 }
12785 {
12788 }
12789 else
12790 {
12793 }
12797 {
12799 {
12804 }
12805 else
12806 {
12811 }
12812 }
12816 {
12818 {
12823 }
12824 else
12825 {
12830 }
12831 }
12832 }
12844 /* Transform comparisons of the form X +- C CMP X. */
12851 {
12858 else
12861 /* (X - c) > X becomes false. */
12865 {
12869 "occur when assuming that (X - c) > X "
12871 WARN_STRICT_OVERFLOW_ALL);
12873 }
12875 /* Likewise (X + c) < X becomes false. */
12879 {
12883 "occur when assuming that "
12885 WARN_STRICT_OVERFLOW_ALL);
12887 }
12889 /* Convert (X - c) <= X to true. */
12894 {
12898 "occur when assuming that "
12900 WARN_STRICT_OVERFLOW_ALL);
12902 }
12904 /* Convert (X + c) >= X to true. */
12909 {
12913 "occur when assuming that "
12915 WARN_STRICT_OVERFLOW_ALL);
12917 }
12920 {
12921 /* Convert X + c > X and X - c < X to true for integers. */
12925 {
12928 "not occur when assuming that "
12930 WARN_STRICT_OVERFLOW_ALL);
12932 }
12937 {
12940 "not occur when assuming that "
12942 WARN_STRICT_OVERFLOW_ALL);
12944 }
12946 /* Convert X + c <= X and X - c >= X to false for integers. */
12950 {
12953 "not occur when assuming that "
12955 WARN_STRICT_OVERFLOW_ALL);
12957 }
12962 {
12965 "not occur when assuming that "
12967 WARN_STRICT_OVERFLOW_ALL);
12969 }
12970 }
12971 }
12973 /* Comparisons with the highest or lowest possible integer of
12974 the specified precision will have known values. */
12975 {
12981 {
12988 {
13001 /* The GE_EXPR and LT_EXPR cases above are not normally
13002 reached because of previous transformations. */
13006 }
13009 {
13016 arg1);
13022 arg0),
13023 arg1);
13026 }
13029 {
13044 }
13047 {
13054 arg1);
13060 arg0),
13061 arg1);
13064 }
13068 /* We will flip the signedness of the comparison operator
13069 associated with the mode of arg1, so the sign bit is
13070 specified by this mode. Check that arg1 is the signed
13071 max associated with this sign bit. */
13073 /* signed_type does not work on pointer types. */
13075 {
13076 /* The following case also applies to X < signed_max+1
13077 and X >= signed_max+1 because previous transformations. */
13079 {
13085 }
13086 }
13087 }
13088 }
13090 /* If we are comparing an ABS_EXPR with a constant, we can
13091 convert all the cases into explicit comparisons, but they may
13092 well not be faster than doing the ABS and one comparison.
13093 But ABS (X) <= C is a range comparison, which becomes a subtraction
13094 and a comparison, and is probably faster. */
13108 /* Convert ABS_EXPR<x> >= 0 to true. */
13115 {
13118 "when simplifying comparison of "
13120 WARN_STRICT_OVERFLOW_CONDITIONAL);
13123 arg0);
13124 }
13126 /* Convert ABS_EXPR<x> < 0 to false. */
13131 {
13134 "when simplifying comparison of "
13136 WARN_STRICT_OVERFLOW_CONDITIONAL);
13139 arg0);
13140 }
13142 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13143 and similarly for >= into !=. */
13153 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13154 otherwise Y might be >= # of bits in X's type and thus e.g.
13155 (unsigned char) (1 << Y) for Y 15 might be 0.
13156 If the cast is widening, then 1 << Y should have unsigned type,
13157 otherwise if Y is number of bits in the signed shift type minus 1,
13158 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13159 31 might be 0xffffffff80000000. */
13170 {
13176 }
13189 {
13193 }
13195 /* If the first operand is NaN, the result is constant. */
13199 {
13201 ? integer_zero_node
13204 }
13206 /* If the second operand is NaN, the result is constant. */
13210 {
13212 ? integer_zero_node
13215 }
13217 /* Simplify unordered comparison of something with itself. */
13223 && !flag_trapping_math
13227 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13228 {
13240 }
13245 /* When pedantic, a compound expression can be neither an lvalue
13246 nor an integer constant expression. */
13249 /* Don't let (0, 0) be null pointer constant. */
13255 /* An ASSERT_EXPR should never be passed to fold_binary. */
13261 }
13263 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13264 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13265 of GOTO_EXPR. */
13267 static tree
13269 {
13271 {
13278 /* ... fall through ... */
13282 }
13283 }
13285 /* Return whether the sub-tree ST contains a label which is accessible from
13286 outside the sub-tree. */
13288 static bool
13290 {
13291 return
13293 }
13295 /* Fold a ternary expression of code CODE and type TYPE with operands
13296 OP0, OP1, and OP2. Return the folded expression if folding is
13297 successful. Otherwise, return NULL_TREE. */
13299 tree
13302 {
13303 tree tem;
13310 /* If this is a commutative operation, and OP0 is a constant, move it
13311 to OP1 to reduce the number of tests below. */
13320 /* Strip any conversions that don't change the mode. This is safe
13321 for every expression, except for a comparison expression because
13322 its signedness is derived from its operands. So, in the latter
13323 case, only strip conversions that don't change the signedness.
13325 Note that this is done as an internal manipulation within the
13326 constant folder, in order to find the simplest representation of
13327 the arguments so that their form can be studied. In any cases,
13328 the appropriate type conversions should be put back in the tree
13329 that will get out of the constant folder. */
13331 {
13334 }
13337 {
13340 }
13343 {
13346 }
13349 {
13353 {
13359 }
13364 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13365 so all simple results must be passed through pedantic_non_lvalue. */
13367 {
13370 /* Only optimize constant conditions when the selected branch
13371 has the same type as the COND_EXPR. This avoids optimizing
13372 away "c ? x : throw", where the throw has a void type.
13373 Avoid throwing away that operand which contains label. */
13380 }
13382 {
13387 {
13392 {
13400 }
13404 }
13405 }
13407 /* If we have A op B ? A : C, we may be able to convert this to a
13408 simpler expression, depending on the operation and the values
13409 of B and C. Signed zeros prevent all of these transformations,
13410 for reasons given above each one.
13412 Also try swapping the arguments and inverting the conditional. */
13417 {
13421 }
13425 op2,
13428 {
13432 {
13436 }
13437 }
13439 /* If the second operand is simpler than the third, swap them
13440 since that produces better jump optimization results. */
13443 {
13445 /* See if this can be inverted. If it can't, possibly because
13446 it was a floating-point inequality comparison, don't do
13447 anything. */
13451 }
13453 /* Convert A ? 1 : 0 to simply A. */
13458 /* If we try to convert OP0 to our type, the
13459 call to fold will try to move the conversion inside
13460 a COND, which will recurse. In that case, the COND_EXPR
13461 is probably the best choice, so leave it alone. */
13465 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13466 over COND_EXPR in cases such as floating point comparisons. */
13475 arg0)));
13477 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13482 {
13483 /* sign_bit_p looks through both zero and sign extensions,
13484 but for this optimization only sign extensions are
13485 usable. */
13488 {
13491 {
13494 }
13496 }
13497 /* sign_bit_p only checks ARG1 bits within A's precision.
13498 If <sign bit of A> has wider type than A, bits outside
13499 of A's precision in <sign bit of A> need to be checked.
13500 If they are all 0, this optimization needs to be done
13501 in unsigned A's type, if they are all 1 in signed A's type,
13502 otherwise this can't be done. */
13508 {
13510 tree tem_type;
13523 {
13526 }
13528 {
13531 }
13532 else
13534 }
13537 return
13543 arg1)));
13544 }
13546 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13547 already handled above. */
13552 {
13561 }
13563 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13564 is probably obsolete because the first operand should be a
13565 truth value (that's why we have the two cases above), but let's
13566 leave it in until we can confirm this for all front-ends. */
13578 /* Disable the transformations below for vectors, since
13579 fold_binary_op_with_conditional_arg may undo them immediately,
13580 yielding an infinite loop. */
13584 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13593 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13598 {
13600 /* Only perform transformation if ARG0 is easily inverted. */
13604 ? BIT_IOR_EXPR
13607 arg1);
13608 }
13610 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13615 {
13617 /* Only perform transformation if ARG0 is easily inverted. */
13623 op2);
13624 }
13626 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13638 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13639 of fold_ternary on them. */
13649 {
13659 {
13664 {
13672 }
13674 /* Constructor elements can be subvectors. */
13677 {
13681 }
13683 /* We keep an exact subset of the constructor elements. */
13685 {
13691 {
13695 }
13703 CONSTRUCTOR_ELT
13706 }
13707 /* The bitfield references a single constructor element. */
13709 {
13714 else
13718 }
13719 }
13720 }
13722 /* A bit-field-ref that referenced the full argument can be stripped. */
13728 /* On constants we can use native encode/interpret to constant
13729 fold (nearly) all BIT_FIELD_REFs. */
13733 /* This limitation should not be necessary, we just need to
13734 round this up to mode size. */
13736 /* Need bit-shifting of the buffer to relax the following. */
13738 {
13743 /* ??? We cannot tell native_encode_expr to start at
13744 some random byte only. So limit us to a reasonable amount
13745 of work. */
13747 {
13752 {
13758 }
13759 }
13760 }
13765 /* For integers we can decompose the FMA if possible. */
13777 {
13793 {
13798 /* Make sure that the perm value is in an acceptable
13799 range. */
13808 else
13813 }
13816 {
13821 }
13826 {
13831 }
13837 {
13841 }
13846 /* Some targets are deficient and fail to expand a single
13847 argument permutation while still allowing an equivalent
13848 2-argument version. */
13852 {
13855 }
13858 {
13865 }
13869 }
13875 }
13877 /* Perform constant folding and related simplification of EXPR.
13878 The related simplifications include x*1 => x, x*0 => 0, etc.,
13879 and application of the associative law.
13880 NOP_EXPR conversions may be removed freely (as long as we
13881 are careful not to change the type of the overall expression).
13882 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13883 but we can constant-fold them if they have constant operands. */
13885 #ifdef ENABLE_FOLD_CHECKING
13886 # define fold(x) fold_1 (x)
13888 static
13889 #endif
13890 tree
13892 {
13896 tree tem;
13899 /* Return right away if a constant. */
13903 /* CALL_EXPR-like objects with variable numbers of operands are
13904 treated specially. */
13906 {
13908 {
13911 }
13913 }
13916 {
13921 {
13939 }
13940 }
13943 {
13945 {
13952 {
13957 /* Find a matching index by means of a binary search. */
13959 {
13975 else
13977 }
13978 }
13981 }
13983 /* Return a VECTOR_CST if possible. */
13985 {
13992 tree value;
13995 {
13999 {
14002 }
14003 else
14005 }
14010 }
14018 }
14020 #ifdef ENABLE_FOLD_CHECKING
14021 #undef fold
14028 /* When --enable-checking=fold, compute a digest of expr before
14029 and after actual fold call to see if fold did not accidentally
14030 change original expr. */
14032 tree
14034 {
14035 tree ret;
14055 }
14057 void
14059 {
14070 }
14072 static void
14074 {
14076 }
14078 static void
14081 {
14087 recursive_label:
14097 {
14098 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
14103 }
14110 {
14111 /* Allow these fields to be modified. */
14112 tree tmp;
14120 {
14123 }
14124 }
14135 {
14138 {
14153 }
14157 {
14170 }
14187 {
14193 }
14196 {
14198 {
14201 }
14203 }
14214 {
14217 }
14227 }
14228 }
14230 /* Helper function for outputting the checksum of a tree T. When
14231 debugging with gdb, you can "define mynext" to be "next" followed
14232 by "call debug_fold_checksum (op0)", then just trace down till the
14233 outputs differ. */
14235 DEBUG_FUNCTION void
14237 {
14252 }
14254 #endif
14256 /* Fold a unary tree expression with code CODE of type TYPE with an
14257 operand OP0. LOC is the location of the resulting expression.
14258 Return a folded expression if successful. Otherwise, return a tree
14259 expression with code CODE of type TYPE with an operand OP0. */
14261 tree
14264 {
14265 tree tem;
14266 #ifdef ENABLE_FOLD_CHECKING
14275 #endif
14281 #ifdef ENABLE_FOLD_CHECKING
14288 #endif
14290 }
14292 /* Fold a binary tree expression with code CODE of type TYPE with
14293 operands OP0 and OP1. LOC is the location of the resulting
14294 expression. Return a folded expression if successful. Otherwise,
14295 return a tree expression with code CODE of type TYPE with operands
14296 OP0 and OP1. */
14298 tree
14301 MEM_STAT_DECL)
14302 {
14303 tree tem;
14304 #ifdef ENABLE_FOLD_CHECKING
14321 #endif
14327 #ifdef ENABLE_FOLD_CHECKING
14342 #endif
14344 }
14346 /* Fold a ternary tree expression with code CODE of type TYPE with
14347 operands OP0, OP1, and OP2. Return a folded expression if
14348 successful. Otherwise, return a tree expression with code CODE of
14349 type TYPE with operands OP0, OP1, and OP2. */
14351 tree
14354 {
14355 tree tem;
14356 #ifdef ENABLE_FOLD_CHECKING
14380 #endif
14387 #ifdef ENABLE_FOLD_CHECKING
14410 #endif
14412 }
14414 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14415 arguments in ARGARRAY, and a null static chain.
14416 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14417 of type TYPE from the given operands as constructed by build_call_array. */
14419 tree
14422 {
14423 tree tem;
14424 #ifdef ENABLE_FOLD_CHECKING
14443 #endif
14449 #ifdef ENABLE_FOLD_CHECKING
14465 #endif
14467 }
14469 /* Perform constant folding and related simplification of initializer
14470 expression EXPR. These behave identically to "fold_buildN" but ignore
14471 potential run-time traps and exceptions that fold must preserve. */
14473 #define START_FOLD_INIT \
14474 int saved_signaling_nans = flag_signaling_nans;\
14475 int saved_trapping_math = flag_trapping_math;\
14476 int saved_rounding_math = flag_rounding_math;\
14477 int saved_trapv = flag_trapv;\
14478 int saved_folding_initializer = folding_initializer;\
14479 flag_signaling_nans = 0;\
14480 flag_trapping_math = 0;\
14481 flag_rounding_math = 0;\
14482 flag_trapv = 0;\
14483 folding_initializer = 1;
14485 #define END_FOLD_INIT \
14486 flag_signaling_nans = saved_signaling_nans;\
14487 flag_trapping_math = saved_trapping_math;\
14488 flag_rounding_math = saved_rounding_math;\
14489 flag_trapv = saved_trapv;\
14490 folding_initializer = saved_folding_initializer;
14492 tree
14495 {
14496 tree result;
14497 START_FOLD_INIT;
14501 END_FOLD_INIT;
14503 }
14505 tree
14508 {
14509 tree result;
14510 START_FOLD_INIT;
14514 END_FOLD_INIT;
14516 }
14518 tree
14521 {
14522 tree result;
14523 START_FOLD_INIT;
14527 END_FOLD_INIT;
14529 }
14531 #undef START_FOLD_INIT
14532 #undef END_FOLD_INIT
14534 /* Determine if first argument is a multiple of second argument. Return 0 if
14535 it is not, or we cannot easily determined it to be.
14537 An example of the sort of thing we care about (at this point; this routine
14538 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14539 fold cases do now) is discovering that
14541 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14543 is a multiple of
14545 SAVE_EXPR (J * 8)
14547 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14549 This code also handles discovering that
14551 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14553 is a multiple of 8 so we don't have to worry about dealing with a
14554 possible remainder.
14556 Note that we *look* inside a SAVE_EXPR only to determine how it was
14557 calculated; it is not safe for fold to do much of anything else with the
14558 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14559 at run time. For example, the latter example above *cannot* be implemented
14560 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14561 evaluation time of the original SAVE_EXPR is not necessarily the same at
14562 the time the new expression is evaluated. The only optimization of this
14563 sort that would be valid is changing
14565 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14567 divided by 8 to
14569 SAVE_EXPR (I) * SAVE_EXPR (J)
14571 (where the same SAVE_EXPR (J) is used in the original and the
14572 transformed version). */
14574 int
14576 {
14584 {
14586 /* Bitwise and provides a power of two multiple. If the mask is
14587 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14590 /* FALLTHRU */
14603 {
14607 /* const_binop may not detect overflow correctly,
14608 so check for it explicitly here. */
14612 size_one_node,
14613 op1)))
14616 }
14620 /* Can't handle conversions from non-integral or wider integral type. */
14626 /* .. fall through ... */
14643 SIGNED);
14647 }
14648 }
14650 /* Return true if CODE or TYPE is known to be non-negative. */
14652 static bool
14654 {
14657 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14658 have a signed:1 type (where the value is -1 and 0). */
14661 }
14663 /* Return true if (CODE OP0) is known to be non-negative. If the return
14664 value is based on the assumption that signed overflow is undefined,
14665 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14666 *STRICT_OVERFLOW_P. */
14668 bool
14671 {
14676 {
14678 /* We can't return 1 if flag_wrapv is set because
14679 ABS_EXPR<INT_MIN> = INT_MIN. */
14683 {
14686 }
14693 strict_overflow_p);
14695 CASE_CONVERT:
14696 {
14701 {
14704 strict_overflow_p);
14706 {
14710 strict_overflow_p);
14711 }
14712 }
14714 {
14717 strict_overflow_p);
14721 }
14722 }
14727 }
14729 /* We don't know sign of `t', so be conservative and return false. */
14731 }
14733 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14734 value is based on the assumption that signed overflow is undefined,
14735 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14736 *STRICT_OVERFLOW_P. */
14738 bool
14741 {
14746 {
14751 strict_overflow_p)
14753 strict_overflow_p));
14755 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14756 both unsigned and at least 2 bits shorter than the result. */
14760 {
14765 {
14769 }
14770 }
14775 {
14776 /* x * x is always non-negative for floating point x
14777 or without overflow. */
14781 {
14786 }
14787 }
14789 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14790 both unsigned and their total bits is shorter than the result. */
14794 {
14813 {
14823 }
14824 }
14830 strict_overflow_p)
14832 strict_overflow_p));
14843 strict_overflow_p)
14845 strict_overflow_p));
14852 strict_overflow_p);
14855 }
14857 /* We don't know sign of `t', so be conservative and return false. */
14859 }
14861 /* Return true if T is known to be non-negative. If the return
14862 value is based on the assumption that signed overflow is undefined,
14863 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14864 *STRICT_OVERFLOW_P. */
14866 bool
14868 {
14873 {
14885 strict_overflow_p)
14887 strict_overflow_p));
14891 }
14892 /* We don't know sign of `t', so be conservative and return false. */
14894 }
14896 /* Return true if T is known to be non-negative. If the return
14897 value is based on the assumption that signed overflow is undefined,
14898 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14899 *STRICT_OVERFLOW_P. */
14901 bool
14904 {
14907 {
14927 /* Always true. */
14931 /* sqrt(-0.0) is -0.0. */
14935 strict_overflow_p);
14972 /* True if the 1st argument is nonnegative. */
14974 strict_overflow_p);
14977 /* True if the 1st OR 2nd arguments are nonnegative. */
14979 strict_overflow_p)
14981 strict_overflow_p)));
14984 /* True if the 1st AND 2nd arguments are nonnegative. */
14986 strict_overflow_p)
14988 strict_overflow_p)));
14991 /* True if the 2nd argument is nonnegative. */
14993 strict_overflow_p);
14996 /* True if the 1st argument is nonnegative or the second
14997 argument is an even integer. */
15002 strict_overflow_p);
15005 /* True if the 1st argument is nonnegative or the second
15006 argument is an even integer valued real. */
15008 {
15009 REAL_VALUE_TYPE c;
15010 HOST_WIDE_INT n;
15015 {
15016 REAL_VALUE_TYPE cint;
15020 }
15021 }
15023 strict_overflow_p);
15027 }
15029 type);
15030 }
15032 /* Return true if T is known to be non-negative. If the return
15033 value is based on the assumption that signed overflow is undefined,
15034 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15035 *STRICT_OVERFLOW_P. */
15037 static bool
15039 {
15045 {
15047 {
15051 /* If the initializer is non-void, then it's a normal expression
15052 that will be assigned to the slot. */
15056 /* Otherwise, the initializer sets the slot in some way. One common
15057 way is an assignment statement at the end of the initializer. */
15059 {
15067 else
15069 }
15073 strict_overflow_p);
15076 }
15079 {
15085 arg0,
15086 arg1,
15087 strict_overflow_p);
15088 }
15092 strict_overflow_p);
15095 strict_overflow_p);
15098 strict_overflow_p);
15103 }
15105 /* We don't know sign of `t', so be conservative and return false. */
15107 }
15109 /* Return true if T is known to be non-negative. If the return
15110 value is based on the assumption that signed overflow is undefined,
15111 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15112 *STRICT_OVERFLOW_P. */
15114 bool
15116 {
15123 {
15130 strict_overflow_p);
15136 strict_overflow_p);
15145 }
15148 {
15156 strict_overflow_p);
15161 strict_overflow_p);
15174 }
15175 }
15177 /* Return true if `t' is known to be non-negative. Handle warnings
15178 about undefined signed overflow. */
15180 bool
15182 {
15189 "determining that expression is always "
15191 WARN_STRICT_OVERFLOW_MISC);
15193 }
15196 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15197 For floating point we further ensure that T is not denormal.
15198 Similar logic is present in nonzero_address in rtlanal.h.
15200 If the return value is based on the assumption that signed overflow
15201 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15202 change *STRICT_OVERFLOW_P. */
15204 bool
15207 {
15209 {
15212 strict_overflow_p);
15215 {
15221 strict_overflow_p));
15222 }
15227 strict_overflow_p);
15231 }
15234 }
15236 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15237 For floating point we further ensure that T is not denormal.
15238 Similar logic is present in nonzero_address in rtlanal.h.
15240 If the return value is based on the assumption that signed overflow
15241 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15242 change *STRICT_OVERFLOW_P. */
15244 bool
15246 tree type,
15247 tree op0,
15249 {
15252 {
15256 {
15257 /* With the presence of negative values it is hard
15258 to say something. */
15265 /* One of operands must be positive and the other non-negative. */
15266 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15267 overflows, on a twos-complement machine the sum of two
15268 nonnegative numbers can never be zero. */
15270 strict_overflow_p)
15272 strict_overflow_p));
15273 }
15278 {
15280 strict_overflow_p)
15282 strict_overflow_p))
15283 {
15286 }
15287 }
15296 {
15299 }
15306 {
15310 /* When both operands are nonzero, then MAX must be too. */
15312 strict_overflow_p))
15315 /* MAX where operand 0 is positive is positive. */
15317 strict_overflow_p);
15318 }
15319 /* MAX where operand 1 is positive is positive. */
15324 {
15328 }
15333 strict_overflow_p)
15335 strict_overflow_p));
15339 }
15342 }
15344 /* Return true when T is an address and is known to be nonzero.
15345 For floating point we further ensure that T is not denormal.
15346 Similar logic is present in nonzero_address in rtlanal.h.
15348 If the return value is based on the assumption that signed overflow
15349 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15350 change *STRICT_OVERFLOW_P. */
15352 bool
15354 {
15357 {
15362 {
15371 /* For objects in symbol table check if we know they are non-zero.
15372 Don't do anything for variables and functions before symtab is built;
15373 it is quite possible that they will be declared weak later. */
15375 {
15381 else
15383 }
15385 /* Function local objects are never NULL. */
15392 /* Constants are never weak. */
15397 }
15405 {
15409 }
15414 }
15416 }
15418 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15419 attempt to fold the expression to a constant without modifying TYPE,
15420 OP0 or OP1.
15422 If the expression could be simplified to a constant, then return
15423 the constant. If the expression would not be simplified to a
15424 constant, then return NULL_TREE. */
15426 tree
15428 {
15431 }
15433 /* Given the components of a unary expression CODE, TYPE and OP0,
15434 attempt to fold the expression to a constant without modifying
15435 TYPE or OP0.
15437 If the expression could be simplified to a constant, then return
15438 the constant. If the expression would not be simplified to a
15439 constant, then return NULL_TREE. */
15441 tree
15443 {
15446 }
15448 /* If EXP represents referencing an element in a constant string
15449 (either via pointer arithmetic or array indexing), return the
15450 tree representing the value accessed, otherwise return NULL. */
15452 tree
15454 {
15458 {
15460 tree index;
15461 tree string;
15466 else
15467 {
15471 /* Optimize the special-case of a zero lower bound.
15473 We convert the low_bound to sizetype to avoid some problems
15474 with constant folding. (E.g. suppose the lower bound is 1,
15475 and its mode is QI. Without the conversion,l (ARRAY
15476 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15477 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15483 }
15496 }
15498 }
15500 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15501 an integer constant, real, or fixed-point constant.
15503 TYPE is the type of the result. */
15505 static tree
15507 {
15511 {
15513 {
15520 }
15527 {
15528 FIXED_VALUE_TYPE f;
15533 /* Propagate overflow flags. */
15537 }
15541 }
15544 }
15546 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15547 an integer constant or real constant.
15549 TYPE is the type of the result. */
15551 tree
15553 {
15557 {
15559 {
15560 /* If the value is unsigned or non-negative, then the absolute value
15561 is the same as the ordinary value. */
15565 /* If the value is negative, then the absolute value is
15566 its negation. */
15567 else
15568 {
15573 }
15574 }
15580 else
15586 }
15589 }
15591 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15592 constant. TYPE is the type of the result. */
15594 static tree
15596 {
15600 }
15602 /* Given CODE, a relational operator, the target type, TYPE and two
15603 constant operands OP0 and OP1, return the result of the
15604 relational operation. If the result is not a compile time
15605 constant, then return NULL_TREE. */
15607 static tree
15609 {
15612 /* From here on, the only cases we handle are when the result is
15613 known to be a constant. */
15616 {
15620 /* Handle the cases where either operand is a NaN. */
15622 {
15624 {
15652 }
15655 }
15658 }
15661 {
15665 }
15667 /* Handle equality/inequality of complex constants. */
15669 {
15680 else
15682 }
15685 {
15692 {
15704 }
15707 }
15709 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15711 To compute GT, swap the arguments and do LT.
15712 To compute GE, do LT and invert the result.
15713 To compute LE, swap the arguments, do LT and invert the result.
15714 To compute NE, do EQ and invert the result.
15716 Therefore, the code below must handle only EQ and LT. */
15719 {
15724 }
15726 /* Note that it is safe to invert for real values here because we
15727 have already handled the one case that it matters. */
15731 {
15734 }
15736 /* Compute a result for LT or EQ if args permit;
15737 Otherwise return T. */
15739 {
15742 else
15744 }
15745 else
15751 }
15753 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15754 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15755 itself. */
15757 tree
15759 {
15760 /* If the expression does not have side effects then we don't have to wrap
15761 it with a cleanup point expression. */
15765 /* If the expression is a return, check to see if the expression inside the
15766 return has no side effects or the right hand side of the modify expression
15767 inside the return. If either don't have side effects set we don't need to
15768 wrap the expression in a cleanup point expression. Note we don't check the
15769 left hand side of the modify because it should always be a return decl. */
15771 {
15778 }
15781 }
15783 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15784 of an indirection through OP0, or NULL_TREE if no simplification is
15785 possible. */
15787 tree
15789 {
15791 tree subtype;
15799 {
15802 /* *&CONST_DECL -> to the value of the const decl. */
15805 /* *&p => p; make sure to handle *&"str"[cst] here. */
15807 {
15811 else
15813 }
15814 /* *(foo *)&fooarray => fooarray[0] */
15817 && (!in_gimple_form
15819 {
15829 }
15830 /* *(foo *)&complexfoo => __real__ complexfoo */
15834 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15837 {
15841 }
15842 }
15846 {
15852 {
15853 tree op00type;
15857 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15860 {
15872 }
15873 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15876 {
15880 }
15881 /* ((foo *)&fooarray)[1] => fooarray[1] */
15884 {
15894 }
15895 }
15896 }
15898 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15901 && (!in_gimple_form
15903 {
15904 tree type_domain;
15914 NULL_TREE);
15915 }
15918 }
15920 /* Builds an expression for an indirection through T, simplifying some
15921 cases. */
15923 tree
15925 {
15933 }
15935 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15937 tree
15939 {
15944 else
15946 }
15948 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15949 whose result is ignored. The type of the returned tree need not be
15950 the same as the original expression. */
15952 tree
15954 {
15960 {
15971 else
15977 {
15993 }
15998 }
15999 }
16001 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16003 tree
16005 {
16011 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16012 have to do anything. Only do this when we are not given a const,
16013 because in that case, this check is more expensive than just
16014 doing it. */
16016 {
16021 }
16023 /* If divisor is a power of two, simplify this to bit manipulation. */
16025 {
16027 {
16041 }
16042 else
16043 {
16044 tree t;
16050 }
16051 }
16052 else
16053 {
16058 }
16061 }
16063 /* Likewise, but round down. */
16065 tree
16067 {
16074 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16075 have to do anything. Only do this when we are not given a const,
16076 because in that case, this check is more expensive than just
16077 doing it. */
16079 {
16084 }
16086 /* If divisor is a power of two, simplify this to bit manipulation. */
16088 {
16089 tree t;
16093 }
16094 else
16095 {
16100 }
16103 }
16105 /* Returns the pointer to the base of the object addressed by EXP and
16106 extracts the information about the offset of the access, storing it
16107 to PBITPOS and POFFSET. */
16109 static tree
16112 {
16113 tree core;
16114 machine_mode mode;
16116 HOST_WIDE_INT bitsize;
16120 {
16125 }
16126 else
16127 {
16131 }
16134 }
16136 /* Returns true if addresses of E1 and E2 differ by a constant, false
16137 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16139 bool
16141 {
16155 {
16165 }
16167 {
16168 /* If only one of the offsets is non-constant, the difference cannot
16169 be a constant. */
16171 }
16172 else
16177 }
16179 /* Simplify the floating point expression EXP when the sign of the
16180 result is not significant. Return NULL_TREE if no simplification
16181 is possible. */
16183 tree
16185 {
16190 {
16226 {
16229 {
16231 /* Strip copysign function call, return the 1st argument. */
16237 /* Strip sign ops from the argument of "odd" math functions. */
16239 {
16243 }
16245 }
16246 }
16251 }
16253 }
16255 /* Return OFF converted to a pointer offset type suitable as offset for
16256 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16257 tree
16259 {
16261 }
16263 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16264 tree
16266 {
16269 }
16271 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16272 tree
16274 {
16277 }