| blob | 3654fd670b064ff83788a9655c740532bce3449b |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
103 /* Nonzero if we are folding constants inside an initializer; zero
104 otherwise. */
107 /* The following constants represent a bit based encoding of GCC's
108 comparison operators. This encoding simplifies transformations
109 on relational comparison operators, such as AND and OR. */
127 };
145 HOST_WIDE_INT *,
178 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
179 Otherwise, return LOC. */
181 static location_t
183 {
186 }
188 /* Similar to protected_set_expr_location, but never modify x in place,
189 if location can and needs to be set, unshare it. */
193 {
199 {
202 }
204 }
205 \f
206 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
207 division and returns the quotient. Otherwise returns
208 NULL_TREE. */
210 tree
212 {
213 widest_int quo;
220 }
221 \f
222 /* This is nonzero if we should defer warnings about undefined
223 overflow. This facility exists because these warnings are a
224 special case. The code to estimate loop iterations does not want
225 to issue any warnings, since it works with expressions which do not
226 occur in user code. Various bits of cleanup code call fold(), but
227 only use the result if it has certain characteristics (e.g., is a
228 constant); that code only wants to issue a warning if the result is
229 used. */
233 /* If a warning about undefined overflow is deferred, this is the
234 warning. Note that this may cause us to turn two warnings into
235 one, but that is fine since it is sufficient to only give one
236 warning per expression. */
240 /* If a warning about undefined overflow is deferred, this is the
241 level at which the warning should be emitted. */
245 /* Start deferring overflow warnings. We could use a stack here to
246 permit nested calls, but at present it is not necessary. */
248 void
250 {
252 }
254 /* Stop deferring overflow warnings. If there is a pending warning,
255 and ISSUE is true, then issue the warning if appropriate. STMT is
256 the statement with which the warning should be associated (used for
257 location information); STMT may be NULL. CODE is the level of the
258 warning--a warn_strict_overflow_code value. This function will use
259 the smaller of CODE and the deferred code when deciding whether to
260 issue the warning. CODE may be zero to mean to always use the
261 deferred code. */
263 void
265 {
267 location_t locus;
272 {
278 }
289 /* Use the smallest code level when deciding to issue the
290 warning. */
299 else
302 }
304 /* Stop deferring overflow warnings, ignoring any deferred
305 warnings. */
307 void
309 {
311 }
313 /* Whether we are deferring overflow warnings. */
315 bool
317 {
319 }
321 /* This is called when we fold something based on the fact that signed
322 overflow is undefined. */
324 static void
326 {
328 {
331 {
334 }
335 }
338 }
339 \f
340 /* Return true if the built-in mathematical function specified by CODE
341 is odd, i.e. -f(x) == f(-x). */
343 static bool
345 {
347 {
381 }
383 }
385 /* Check whether we may negate an integer constant T without causing
386 overflow. */
388 bool
390 {
391 tree type;
400 }
402 /* Determine whether an expression T can be cheaply negated using
403 the function negate_expr without introducing undefined overflow. */
405 static bool
407 {
408 tree type;
417 {
422 /* Check that -CST will not overflow type. */
435 /* We want to canonicalize to positive real constants. Pretend
436 that only negative ones can be easily negated. */
444 {
455 }
468 /* -(A + B) -> (-B) - A. */
473 /* -(A + B) -> (-A) - B. */
477 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
487 /* Fall through. */
498 /* In general we can't negate A / B, because if A is INT_MIN and
499 B is 1, we may turn this into INT_MIN / -1 which is undefined
500 and actually traps on some architectures. But if overflow is
501 undefined, we can negate, because - (INT_MIN / 1) is an
502 overflow. */
504 {
507 /* If overflow is undefined then we have to be careful because
508 we ask whether it's ok to associate the negate with the
509 division which is not ok for example for
510 -((a - b) / c) where (-(a - b)) / c may invoke undefined
511 overflow because of negating INT_MIN. So do not use
512 negate_expr_p here but open-code the two important cases. */
517 }
523 /* Negate -((double)float) as (double)(-float). */
525 {
529 }
533 /* Negate -f(x) as f(-x). */
539 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
541 {
545 }
550 }
552 }
554 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
555 simplification is possible.
556 If negate_expr_p would return true for T, NULL_TREE will never be
557 returned. */
559 static tree
561 {
563 tree tem;
566 {
567 /* Convert - (~A) to A + 1. */
593 {
598 }
602 {
607 {
611 }
614 }
637 {
638 /* -(A + B) -> (-B) - A. */
642 {
646 }
648 /* -(A + B) -> (-A) - B. */
650 {
654 }
655 }
659 /* - (A - B) -> B - A */
671 /* Fall through. */
675 {
684 }
690 /* In general we can't negate A / B, because if A is INT_MIN and
691 B is 1, we may turn this into INT_MIN / -1 which is undefined
692 and actually traps on some architectures. But if overflow is
693 undefined, we can negate, because - (INT_MIN / 1) is an
694 overflow. */
696 {
701 {
708 }
709 /* If overflow is undefined then we have to be careful because
710 we ask whether it's ok to associate the negate with the
711 division which is not ok for example for
712 -((a - b) / c) where (-(a - b)) / c may invoke undefined
713 overflow because of negating INT_MIN. So do not use
714 negate_expr_p here but open-code the two important cases. */
723 }
727 /* Convert -((double)float) into (double)(-float). */
729 {
733 }
737 /* Negate -f(x) as f(-x). */
740 {
746 }
750 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
752 {
755 {
762 }
763 }
768 }
771 }
773 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
774 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
775 return NULL_TREE. */
777 static tree
779 {
781 location_t loc;
794 }
795 \f
796 /* Split a tree IN into a constant, literal and variable parts that could be
797 combined with CODE to make IN. "constant" means an expression with
798 TREE_CONSTANT but that isn't an actual constant. CODE must be a
799 commutative arithmetic operation. Store the constant part into *CONP,
800 the literal in *LITP and return the variable part. If a part isn't
801 present, set it to null. If the tree does not decompose in this way,
802 return the entire tree as the variable part and the other parts as null.
804 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
805 case, we negate an operand that was subtracted. Except if it is a
806 literal for which we use *MINUS_LITP instead.
808 If NEGATE_P is true, we are negating all of IN, again except a literal
809 for which we use *MINUS_LITP instead.
811 If IN is itself a literal or constant, return it as appropriate.
813 Note that we do not guarantee that any of the three values will be the
814 same type as IN, but they will have the same signedness and mode. */
816 static tree
819 {
826 /* Strip any conversions that don't change the machine mode or signedness. */
835 /* We can associate addition and subtraction together (even
836 though the C standard doesn't say so) for integers because
837 the value is not affected. For reals, the value might be
838 affected, so we can't. */
841 {
847 /* First see if either of the operands is a literal, then a constant. */
860 /* If we haven't dealt with either operand, this is not a case we can
861 decompose. Otherwise, VAR is either of the ones remaining, if any. */
866 else
869 /* Now do any needed negations. */
876 }
879 {
880 /* -X - 1 is folded to ~X, undo that here. */
883 }
886 else
890 {
897 }
900 }
902 /* Re-associate trees split by the above function. T1 and T2 are
903 either expressions to associate or null. Return the new
904 expression, if any. LOC is the location of the new expression. If
905 we build an operation, do it in TYPE and with CODE. */
907 static tree
909 {
915 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
916 try to fold this since we will have infinite recursion. But do
917 deal with any NEGATE_EXPRs. */
920 {
922 {
935 }
937 {
940 }
944 }
948 }
949 \f
950 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
951 for use in int_const_binop, size_binop and size_diffop. */
953 static bool
955 {
962 {
971 }
976 }
979 /* Combine two integer constants ARG1 and ARG2 under operation CODE
980 to produce a new constant. Return NULL_TREE if we don't know how
981 to evaluate CODE at compile-time. */
983 static tree
986 {
987 wide_int res;
988 tree t;
997 {
1013 {
1017 else
1019 }
1022 /* It's unclear from the C standard whether shifts can overflow.
1023 The following code ignores overflow; perhaps a C standard
1024 interpretation ruling is needed. */
1026 else
1033 {
1037 else
1039 }
1043 else
1122 }
1130 }
1132 tree
1134 {
1136 }
1138 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1139 constant. We assume ARG1 and ARG2 have the same data type, or at least
1140 are the same kind of constant and the same machine mode. Return zero if
1141 combining the constants is not allowed in the current operating mode. */
1143 static tree
1145 {
1146 /* Sanity check for the recursive cases. */
1154 {
1160 }
1163 {
1164 machine_mode mode;
1165 REAL_VALUE_TYPE d1;
1166 REAL_VALUE_TYPE d2;
1167 REAL_VALUE_TYPE value;
1168 REAL_VALUE_TYPE result;
1172 /* The following codes are handled by real_arithmetic. */
1174 {
1185 }
1193 /* Don't perform operation if we honor signaling NaNs and
1194 either operand is a NaN. */
1199 /* Don't perform operation if it would raise a division
1200 by zero exception. */
1206 /* If either operand is a NaN, just return it. Otherwise, set up
1207 for floating-point trap; we return an overflow. */
1216 /* Don't constant fold this floating point operation if
1217 the result has overflowed and flag_trapping_math. */
1225 /* Don't constant fold this floating point operation if the
1226 result may dependent upon the run-time rounding mode and
1227 flag_rounding_math is set, or if GCC's software emulation
1228 is unable to accurately represent the result. */
1238 }
1241 {
1242 FIXED_VALUE_TYPE f1;
1243 FIXED_VALUE_TYPE f2;
1244 FIXED_VALUE_TYPE result;
1249 /* The following codes are handled by fixed_arithmetic. */
1251 {
1263 {
1270 }
1275 }
1282 /* Propagate overflow flags. */
1286 }
1289 {
1298 {
1309 mpc_mul);
1323 mpc_div);
1324 /* Fallthru ... */
1330 {
1331 /* Keep this algorithm in sync with
1332 tree-complex.c:expand_complex_div_straight().
1334 Expand complex division to scalars, straightforward algorithm.
1335 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1336 t = br*br + bi*bi
1337 */
1338 tree magsquared
1342 tree t1
1346 tree t2
1353 }
1354 else
1355 {
1356 /* Keep this algorithm in sync with
1357 tree-complex.c:expand_complex_div_wide().
1359 Expand complex division to scalars, modified algorithm to minimize
1360 overflow with wide input ranges. */
1366 {
1367 /* In the TRUE branch, we compute
1368 ratio = br/bi;
1369 div = (br * ratio) + bi;
1370 tr = (ar * ratio) + ai;
1371 ti = (ai * ratio) - ar;
1372 tr = tr / div;
1373 ti = ti / div; */
1384 }
1385 else
1386 {
1387 /* In the FALSE branch, we compute
1388 ratio = d/c;
1389 divisor = (d * ratio) + c;
1390 tr = (b * ratio) + a;
1391 ti = b - (a * ratio);
1392 tr = tr / div;
1393 ti = ti / div; */
1405 }
1406 }
1411 }
1415 }
1419 {
1425 {
1431 /* It is possible that const_binop cannot handle the given
1432 code and return NULL_TREE */
1435 }
1438 }
1440 /* Shifts allow a scalar offset for a vector. */
1443 {
1449 {
1454 /* It is possible that const_binop cannot handle the given
1455 code and return NULL_TREE. */
1458 }
1461 }
1463 }
1465 /* Overload that adds a TYPE parameter to be able to dispatch
1466 to fold_relational_const. */
1468 tree
1470 {
1474 /* ??? Until we make the const_binop worker take the type of the
1475 result as argument put those cases that need it here. */
1477 {
1488 {
1504 {
1510 }
1513 }
1519 {
1544 {
1557 }
1560 }
1563 }
1568 /* Make sure type and arg0 have the same saturating flag. */
1573 }
1575 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1576 Return zero if computing the constants is not possible. */
1578 tree
1580 {
1582 {
1583 CASE_CONVERT:
1598 {
1599 /* Can't call fold_negate_const directly here as that doesn't
1600 handle all cases and we might not be able to negate some
1601 constants. */
1606 }
1615 {
1619 }
1625 /* Perform BIT_NOT_EXPR on each element individually. */
1627 {
1629 tree elem;
1634 {
1640 }
1643 }
1665 {
1684 else
1688 {
1692 }
1695 }
1700 {
1714 {
1719 }
1722 {
1726 }
1729 }
1733 }
1736 }
1738 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1739 indicates which particular sizetype to create. */
1741 tree
1743 {
1745 }
1746 \f
1747 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1748 is a tree code. The type of the result is taken from the operands.
1749 Both must be equivalent integer types, ala int_binop_types_match_p.
1750 If the operands are constant, so is the result. */
1752 tree
1754 {
1763 /* Handle the special case of two integer constants faster. */
1765 {
1766 /* And some specific cases even faster than that. */
1768 {
1773 }
1775 {
1778 }
1780 {
1783 }
1785 /* Handle general case of two integer constants. For sizetype
1786 constant calculations we always want to know about overflow,
1787 even in the unsigned case. */
1789 }
1792 }
1794 /* Given two values, either both of sizetype or both of bitsizetype,
1795 compute the difference between the two values. Return the value
1796 in signed type corresponding to the type of the operands. */
1798 tree
1800 {
1802 tree ctype;
1807 /* If the type is already signed, just do the simple thing. */
1815 else
1818 /* If either operand is not a constant, do the conversions to the signed
1819 type and subtract. The hardware will do the right thing with any
1820 overflow in the subtraction. */
1826 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1827 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1828 overflow) and negate (which can't either). Special-case a result
1829 of zero while we're here. */
1835 else
1839 MINUS_EXPR,
1841 }
1842 \f
1843 /* A subroutine of fold_convert_const handling conversions of an
1844 INTEGER_CST to another integer type. */
1846 static tree
1848 {
1849 /* Given an integer constant, make new constant with new type,
1850 appropriately sign-extended or truncated. Use widest_int
1851 so that any extension is done according ARG1's type. */
1855 }
1857 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1858 to an integer type. */
1860 static tree
1862 {
1864 tree t;
1866 /* The following code implements the floating point to integer
1867 conversion rules required by the Java Language Specification,
1868 that IEEE NaNs are mapped to zero and values that overflow
1869 the target precision saturate, i.e. values greater than
1870 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1871 are mapped to INT_MIN. These semantics are allowed by the
1872 C and C++ standards that simply state that the behavior of
1873 FP-to-integer conversion is unspecified upon overflow. */
1875 wide_int val;
1876 REAL_VALUE_TYPE r;
1880 {
1887 }
1889 /* If R is NaN, return zero and show we have an overflow. */
1891 {
1894 }
1896 /* See if R is less than the lower bound or greater than the
1897 upper bound. */
1900 {
1904 {
1907 }
1908 }
1911 {
1914 {
1917 {
1920 }
1921 }
1922 }
1929 }
1931 /* A subroutine of fold_convert_const handling conversions of a
1932 FIXED_CST to an integer type. */
1934 static tree
1936 {
1937 tree t;
1941 /* Right shift FIXED_CST to temp by fbit. */
1945 {
1947 HOST_BITS_PER_DOUBLE_INT,
1950 /* Left shift temp to temp_trunc by fbit. */
1952 HOST_BITS_PER_DOUBLE_INT,
1954 }
1955 else
1956 {
1959 }
1961 /* If FIXED_CST is negative, we need to round the value toward 0.
1962 By checking if the fractional bits are not zero to add 1 to temp. */
1968 /* Given a fixed-point constant, make new constant with new type,
1969 appropriately sign-extended or truncated. */
1977 }
1979 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1980 to another floating point type. */
1982 static tree
1984 {
1985 REAL_VALUE_TYPE value;
1986 tree t;
1991 /* If converting an infinity or NAN to a representation that doesn't
1992 have one, set the overflow bit so that we can produce some kind of
1993 error message at the appropriate point if necessary. It's not the
1994 most user-friendly message, but it's better than nothing. */
2001 /* Regular overflow, conversion produced an infinity in a mode that
2002 can't represent them. */
2007 else
2010 }
2012 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2013 to a floating point type. */
2015 static tree
2017 {
2018 REAL_VALUE_TYPE value;
2019 tree t;
2026 }
2028 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2029 to another fixed-point type. */
2031 static tree
2033 {
2034 FIXED_VALUE_TYPE value;
2035 tree t;
2042 /* Propagate overflow flags. */
2046 }
2048 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2049 to a fixed-point type. */
2051 static tree
2053 {
2054 FIXED_VALUE_TYPE value;
2055 tree t;
2057 double_int di;
2064 else
2072 /* Propagate overflow flags. */
2076 }
2078 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2079 to a fixed-point type. */
2081 static tree
2083 {
2084 FIXED_VALUE_TYPE value;
2085 tree t;
2093 /* Propagate overflow flags. */
2097 }
2099 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2100 type TYPE. If no simplification can be done return NULL_TREE. */
2102 static tree
2104 {
2110 {
2117 }
2119 {
2126 }
2128 {
2135 }
2137 }
2139 /* Construct a vector of zero elements of vector type TYPE. */
2141 static tree
2143 {
2144 tree t;
2148 }
2150 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2152 bool
2154 {
2169 {
2188 }
2189 }
2191 /* Convert expression ARG to type TYPE. Used by the middle-end for
2192 simple conversions in preference to calling the front-end's convert. */
2194 tree
2196 {
2198 tree tem;
2209 {
2212 /* Handle conversions between pointers to different address spaces. */
2217 /* fall through */
2222 {
2226 }
2240 {
2244 }
2246 {
2250 }
2252 {
2256 }
2259 {
2277 }
2282 {
2286 }
2289 {
2303 }
2307 {
2316 integer_zero_node));
2318 {
2322 {
2328 }
2336 }
2340 }
2358 }
2359 fold_convert_exit:
2362 }
2363 \f
2364 /* Return false if expr can be assumed not to be an lvalue, true
2365 otherwise. */
2367 static bool
2369 {
2370 /* We only need to wrap lvalue tree codes. */
2372 {
2403 /* Assume the worst for front-end tree codes. */
2407 }
2410 }
2412 /* Return an expr equal to X but certainly not valid as an lvalue. */
2414 tree
2416 {
2417 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2418 us. */
2425 }
2427 /* When pedantic, return an expr equal to X but certainly not valid as a
2428 pedantic lvalue. Otherwise, return X. */
2430 static tree
2432 {
2434 }
2435 \f
2436 /* Given a tree comparison code, return the code that is the logical inverse.
2437 It is generally not safe to do this for floating-point comparisons, except
2438 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2439 ERROR_MARK in this case. */
2441 enum tree_code
2443 {
2449 {
2480 }
2481 }
2483 /* Similar, but return the comparison that results if the operands are
2484 swapped. This is safe for floating-point. */
2486 enum tree_code
2488 {
2490 {
2516 }
2517 }
2520 /* Convert a comparison tree code from an enum tree_code representation
2521 into a compcode bit-based encoding. This function is the inverse of
2522 compcode_to_comparison. */
2524 static enum comparison_code
2526 {
2528 {
2559 }
2560 }
2562 /* Convert a compcode bit-based encoding of a comparison operator back
2563 to GCC's enum tree_code representation. This function is the
2564 inverse of comparison_to_compcode. */
2566 static enum tree_code
2568 {
2570 {
2601 }
2602 }
2604 /* Return a tree for the comparison which is the combination of
2605 doing the AND or OR (depending on CODE) of the two operations LCODE
2606 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2607 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2608 if this makes the transformation invalid. */
2610 tree
2615 {
2622 {
2633 }
2636 {
2637 /* Eliminate unordered comparisons, as well as LTGT and ORD
2638 which are not used unless the mode has NaNs. */
2644 }
2646 {
2647 /* Check that the original operation and the optimized ones will trap
2648 under the same condition. */
2659 /* In a short-circuited boolean expression the LHS might be
2660 such that the RHS, if evaluated, will never trap. For
2661 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2662 if neither x nor y is NaN. (This is a mixed blessing: for
2663 example, the expression above will never trap, hence
2664 optimizing it to x < y would be invalid). */
2669 /* If the comparison was short-circuited, and only the RHS
2670 trapped, we may now generate a spurious trap. */
2675 /* If we changed the conditions that cause a trap, we lose. */
2678 }
2684 else
2685 {
2690 }
2691 }
2692 \f
2693 /* Return nonzero if two operands (typically of the same tree node)
2694 are necessarily equal. If either argument has side-effects this
2695 function returns zero. FLAGS modifies behavior as follows:
2697 If OEP_ONLY_CONST is set, only return nonzero for constants.
2698 This function tests whether the operands are indistinguishable;
2699 it does not test whether they are equal using C's == operation.
2700 The distinction is important for IEEE floating point, because
2701 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2702 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2704 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2705 even though it may hold multiple values during a function.
2706 This is because a GCC tree node guarantees that nothing else is
2707 executed between the evaluation of its "operands" (which may often
2708 be evaluated in arbitrary order). Hence if the operands themselves
2709 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2710 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2711 unset means assuming isochronic (or instantaneous) tree equivalence.
2712 Unless comparing arbitrary expression trees, such as from different
2713 statements, this flag can usually be left unset.
2715 If OEP_PURE_SAME is set, then pure functions with identical arguments
2716 are considered the same. It is used when the caller has other ways
2717 to ensure that global memory is unchanged in between. */
2719 int
2721 {
2722 /* If either is ERROR_MARK, they aren't equal. */
2728 /* Similar, if either does not have a type (like a released SSA name),
2729 they aren't equal. */
2733 /* Check equality of integer constants before bailing out due to
2734 precision differences. */
2738 /* If both types don't have the same signedness, then we can't consider
2739 them equal. We must check this before the STRIP_NOPS calls
2740 because they may change the signedness of the arguments. As pointers
2741 strictly don't have a signedness, require either two pointers or
2742 two non-pointers as well. */
2747 /* We cannot consider pointers to different address space equal. */
2753 /* If both types don't have the same precision, then it is not safe
2754 to strip NOPs. */
2762 /* In case both args are comparisons but with different comparison
2763 code, try to swap the comparison operands of one arg to produce
2764 a match and compare that variant. */
2768 {
2776 }
2779 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2783 /* This is needed for conversions and for COMPONENT_REF.
2784 Might as well play it safe and always test this. */
2790 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2791 We don't care about side effects in that case because the SAVE_EXPR
2792 takes care of that for us. In all other cases, two expressions are
2793 equal if they have no side effects. If we have two identical
2794 expressions with side effects that should be treated the same due
2795 to the only side effects being identical SAVE_EXPR's, that will
2796 be detected in the recursive calls below.
2797 If we are taking an invariant address of two identical objects
2798 they are necessarily equal as well. */
2805 /* Next handle constant cases, those for which we can return 1 even
2806 if ONLY_CONST is set. */
2809 {
2824 {
2825 /* If we do not distinguish between signed and unsigned zero,
2826 consider them equal. */
2829 }
2833 {
2840 {
2844 }
2846 }
2850 flags)
2852 flags));
2866 }
2871 /* Define macros to test an operand from arg0 and arg1 for equality and a
2872 variant that allows null and views null as being different from any
2873 non-null value. In the latter case, if either is null, the both
2874 must be; otherwise, do the normal comparison. */
2875 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2876 TREE_OPERAND (arg1, N), flags)
2878 #define OP_SAME_WITH_NULL(N) \
2879 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2880 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2883 {
2885 /* Two conversions are equal only if signedness and modes match. */
2887 {
2888 CASE_CONVERT:
2896 }
2906 /* For commutative ops, allow the other order. */
2914 /* If either of the pointer (or reference) expressions we are
2915 dereferencing contain a side effect, these cannot be equal,
2916 but their addresses can be. */
2923 {
2938 /* Require equal access sizes, and similar pointer types.
2939 We can have incomplete types for array references of
2940 variable-sized arrays from the Fortran frontend
2941 though. Also verify the types are compatible. */
2949 || (alias_ptr_types_compatible_p
2961 /* TARGET_MEM_REF require equal extra operands. */
2969 /* Operands 2 and 3 may be null.
2970 Compare the array index by value if it is constant first as we
2971 may have different types but same value here. */
2982 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2983 may be NULL when we're called to compare MEM_EXPRs. */
2998 }
3002 {
3020 /* The multiplcation operands are commutative. */
3021 /* FALLTHRU */
3029 /* Otherwise take into account this is a commutative operation. */
3042 }
3046 {
3050 /* If not both CALL_EXPRs are either internal or normal function
3051 functions, then they are not equal. */
3054 {
3055 /* If the CALL_EXPRs call different internal functions, then they
3056 are not equal. */
3059 }
3060 else
3061 {
3062 /* If the CALL_EXPRs call different functions, then they are not
3063 equal. */
3065 flags))
3067 }
3069 {
3073 else
3077 }
3079 /* Now see if all the arguments are the same. */
3080 {
3091 /* If we get here and both argument lists are exhausted
3092 then the CALL_EXPRs are equal. */
3094 }
3097 }
3100 /* Consider __builtin_sqrt equal to sqrt. */
3108 }
3110 #undef OP_SAME
3111 #undef OP_SAME_WITH_NULL
3112 }
3113 \f
3114 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3115 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3117 When in doubt, return 0. */
3119 static int
3121 {
3133 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3134 and see if the inner values are the same. This removes any
3135 signedness comparison, which doesn't matter here. */
3142 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3143 actual comparison operand, ARG0.
3145 First throw away any conversions to wider types
3146 already present in the operands. */
3155 {
3158 /* Make sure shorter operand is extended the right way
3159 to match the longer operand. */
3165 }
3168 }
3169 \f
3170 /* See if ARG is an expression that is either a comparison or is performing
3171 arithmetic on comparisons. The comparisons must only be comparing
3172 two different values, which will be stored in *CVAL1 and *CVAL2; if
3173 they are nonzero it means that some operands have already been found.
3174 No variables may be used anywhere else in the expression except in the
3175 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3176 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3178 If this is true, return 1. Otherwise, return zero. */
3180 static int
3182 {
3186 /* We can handle some of the tcc_expression cases here. */
3196 {
3197 /* If we've already found a CVAL1 or CVAL2, this expression is
3198 two complex to handle. */
3204 }
3207 {
3230 /* First see if we can handle the first operand, then the second. For
3231 the second operand, we know *CVAL1 can't be zero. It must be that
3232 one side of the comparison is each of the values; test for the
3233 case where this isn't true by failing if the two operands
3234 are the same. */
3243 ;
3247 ;
3248 else
3252 ;
3256 ;
3257 else
3264 }
3265 }
3266 \f
3267 /* ARG is a tree that is known to contain just arithmetic operations and
3268 comparisons. Evaluate the operations in the tree substituting NEW0 for
3269 any occurrence of OLD0 as an operand of a comparison and likewise for
3270 NEW1 and OLD1. */
3272 static tree
3275 {
3280 /* We can handle some of the tcc_expression cases here. */
3288 {
3303 {
3322 }
3323 /* Fall through - ??? */
3326 {
3330 /* We need to check both for exact equality and tree equality. The
3331 former will be true if the operand has a side-effect. In that
3332 case, we know the operand occurred exactly once. */
3345 }
3349 }
3350 }
3351 \f
3352 /* Return a tree for the case when the result of an expression is RESULT
3353 converted to TYPE and OMITTED was previously an operand of the expression
3354 but is now not needed (e.g., we folded OMITTED * 0).
3356 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3357 the conversion of RESULT to TYPE. */
3359 tree
3361 {
3364 /* If the resulting operand is an empty statement, just return the omitted
3365 statement casted to void. */
3375 }
3377 /* Return a tree for the case when the result of an expression is RESULT
3378 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3379 of the expression but are now not needed.
3381 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3382 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3383 evaluated before OMITTED2. Otherwise, if neither has side effects,
3384 just do the conversion of RESULT to TYPE. */
3386 tree
3389 {
3398 }
3400 \f
3401 /* Return a simplified tree node for the truth-negation of ARG. This
3402 never alters ARG itself. We assume that ARG is an operation that
3403 returns a truth value (0 or 1).
3405 FIXME: one would think we would fold the result, but it causes
3406 problems with the dominator optimizer. */
3408 static tree
3410 {
3415 /* If this is a comparison, we can simply invert it, except for
3416 floating-point non-equality comparisons, in which case we just
3417 enclose a TRUTH_NOT_EXPR around what we have. */
3420 {
3423 && flag_trapping_math
3434 }
3437 {
3456 /* Here we can invert either operand. We invert the first operand
3457 unless the second operand is a TRUTH_NOT_EXPR in which case our
3458 result is the XOR of the first operand with the inside of the
3459 negation of the second operand. */
3464 else
3487 {
3494 /* A COND_EXPR may have a throw as one operand, which
3495 then has void type. Just leave void operands
3496 as they are. */
3502 }
3514 CASE_CONVERT:
3518 /* ... fall through ... */
3540 }
3541 }
3543 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3544 assume that ARG is an operation that returns a truth value (0 or 1
3545 for scalars, 0 or -1 for vectors). Return the folded expression if
3546 folding is successful. Otherwise, return NULL_TREE. */
3548 static tree
3550 {
3553 ? BIT_NOT_EXPR
3556 }
3558 /* Return a simplified tree node for the truth-negation of ARG. This
3559 never alters ARG itself. We assume that ARG is an operation that
3560 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3562 tree
3564 {
3570 ? BIT_NOT_EXPR
3573 }
3575 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3576 operands are another bit-wise operation with a common input. If so,
3577 distribute the bit operations to save an operation and possibly two if
3578 constants are involved. For example, convert
3579 (A | B) & (A | C) into A | (B & C)
3580 Further simplification will occur if B and C are constants.
3582 If this optimization cannot be done, 0 will be returned. */
3584 static tree
3587 {
3588 tree common;
3598 {
3602 }
3604 {
3608 }
3610 {
3614 }
3616 {
3620 }
3621 else
3629 }
3631 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3632 with code CODE. This optimization is unsafe. */
3633 static tree
3636 {
3640 /* (A / C) +- (B / C) -> (A +- B) / C. */
3650 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3655 {
3667 }
3670 }
3671 \f
3672 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3673 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3675 static tree
3678 {
3682 {
3689 }
3703 }
3705 /* Optimize a bit-field compare.
3707 There are two cases: First is a compare against a constant and the
3708 second is a comparison of two items where the fields are at the same
3709 bit position relative to the start of a chunk (byte, halfword, word)
3710 large enough to contain it. In these cases we can avoid the shift
3711 implicit in bitfield extractions.
3713 For constants, we emit a compare of the shifted constant with the
3714 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3715 compared. For two fields at the same position, we do the ANDs with the
3716 similar mask and compare the result of the ANDs.
3718 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3719 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3720 are the left and right operands of the comparison, respectively.
3722 If the optimization described above can be done, we return the resulting
3723 tree. Otherwise we return zero. */
3725 static tree
3728 {
3731 tree unsigned_type;
3737 tree mask;
3738 tree offset;
3740 /* Get all the information about the extractions being done. If the bit size
3741 if the same as the size of the underlying object, we aren't doing an
3742 extraction at all and so can do nothing. We also don't want to
3743 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3744 then will no longer be able to replace it. */
3752 {
3753 /* If this is not a constant, we can only do something if bit positions,
3754 sizes, and signedness are the same. */
3762 }
3764 /* See if we can find a mode to refer to this field. We should be able to,
3765 but fail if we can't. */
3774 /* Set signed and unsigned types of the precision of this mode for the
3775 shifts below. */
3778 /* Compute the bit position and size for the new reference and our offset
3779 within it. If the new reference is the same size as the original, we
3780 won't optimize anything, so return zero. */
3790 /* Make the mask to be used against the extracted field. */
3797 /* If not comparing with constant, just rework the comparison
3798 and return. */
3802 unsigned_type,
3805 mask),
3808 unsigned_type,
3811 mask));
3813 /* Otherwise, we are handling the constant case. See if the constant is too
3814 big for the field. Warn and return a tree of for 0 (false) if so. We do
3815 this not only for its own sake, but to avoid having to test for this
3816 error case below. If we didn't, we might generate wrong code.
3818 For unsigned fields, the constant shifted right by the field length should
3819 be all zero. For signed fields, the high-order bits should agree with
3820 the sign bit. */
3823 {
3825 {
3829 }
3830 }
3831 else
3832 {
3835 {
3839 }
3840 }
3842 /* Single-bit compares should always be against zero. */
3844 {
3847 }
3849 /* Make a new bitfield reference, shift the constant over the
3850 appropriate number of bits and mask it with the computed mask
3851 (in case this was a signed field). If we changed it, make a new one. */
3858 mask);
3863 }
3864 \f
3865 /* Subroutine for fold_truth_andor_1: decode a field reference.
3867 If EXP is a comparison reference, we return the innermost reference.
3869 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3870 set to the starting bit number.
3872 If the innermost field can be completely contained in a mode-sized
3873 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3875 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3876 otherwise it is not changed.
3878 *PUNSIGNEDP is set to the signedness of the field.
3880 *PMASK is set to the mask used. This is either contained in a
3881 BIT_AND_EXPR or derived from the width of the field.
3883 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3885 Return 0 if this is not a component reference or is one that we can't
3886 do anything with. */
3888 static tree
3893 {
3897 tree unsigned_type;
3900 /* All the optimizations using this function assume integer fields.
3901 There are problems with FP fields since the type_for_size call
3902 below can fail for, e.g., XFmode. */
3906 /* We are interested in the bare arrangement of bits, so strip everything
3907 that doesn't affect the machine mode. However, record the type of the
3908 outermost expression if it may matter below. */
3915 {
3921 }
3930 /* If the number of bits in the reference is the same as the bitsize of
3931 the outer type, then the outer type gives the signedness. Otherwise
3932 (in case of a small bitfield) the signedness is unchanged. */
3936 /* Compute the mask to access the bitfield. */
3945 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3953 }
3955 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3956 bit positions and MASK is SIGNED. */
3958 static int
3960 {
3964 /* If this function returns true when the type of the mask is
3965 UNSIGNED, then there will be errors. In particular see
3966 gcc.c-torture/execute/990326-1.c. There does not appear to be
3967 any documentation paper trail as to why this is so. But the pre
3968 wide-int worked with that restriction and it has been preserved
3969 here. */
3974 }
3976 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3977 represents the sign bit of EXP's type. If EXP represents a sign
3978 or zero extension, also test VAL against the unextended type.
3979 The return value is the (sub)expression whose sign bit is VAL,
3980 or NULL_TREE otherwise. */
3982 tree
3984 {
3986 tree t;
3988 /* Tree EXP must have an integral type. */
3993 /* Tree VAL must be an integer constant. */
4002 /* Handle extension from a narrower type. */
4008 }
4010 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4011 to be evaluated unconditionally. */
4013 static int
4015 {
4016 /* Strip any conversions that don't change the machine mode. */
4025 /* Don't regard global variables as simple. They may be
4026 allocated in ways unknown to the compiler (shared memory,
4027 #pragma weak, etc). */
4030 /* Weakrefs are not safe to be read, since they can be NULL.
4031 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4032 have DECL_WEAK flag set. */
4034 /* Loading a static variable is unduly expensive, but global
4035 registers aren't expensive. */
4037 }
4039 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4040 to be evaluated unconditionally.
4041 I addition to simple_operand_p, we assume that comparisons, conversions,
4042 and logic-not operations are simple, if their operands are simple, too. */
4044 static bool
4046 {
4066 }
4068 \f
4069 /* The following functions are subroutines to fold_range_test and allow it to
4070 try to change a logical combination of comparisons into a range test.
4072 For example, both
4073 X == 2 || X == 3 || X == 4 || X == 5
4074 and
4075 X >= 2 && X <= 5
4076 are converted to
4077 (unsigned) (X - 2) <= 3
4079 We describe each set of comparisons as being either inside or outside
4080 a range, using a variable named like IN_P, and then describe the
4081 range with a lower and upper bound. If one of the bounds is omitted,
4082 it represents either the highest or lowest value of the type.
4084 In the comments below, we represent a range by two numbers in brackets
4085 preceded by a "+" to designate being inside that range, or a "-" to
4086 designate being outside that range, so the condition can be inverted by
4087 flipping the prefix. An omitted bound is represented by a "-". For
4088 example, "- [-, 10]" means being outside the range starting at the lowest
4089 possible value and ending at 10, in other words, being greater than 10.
4090 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4091 always false.
4093 We set up things so that the missing bounds are handled in a consistent
4094 manner so neither a missing bound nor "true" and "false" need to be
4095 handled using a special case. */
4097 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4098 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4099 and UPPER1_P are nonzero if the respective argument is an upper bound
4100 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4101 must be specified for a comparison. ARG1 will be converted to ARG0's
4102 type if both are specified. */
4104 static tree
4107 {
4108 tree tem;
4112 /* If neither arg represents infinity, do the normal operation.
4113 Else, if not a comparison, return infinity. Else handle the special
4114 comparison rules. Note that most of the cases below won't occur, but
4115 are handled for consistency. */
4118 {
4123 }
4128 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4129 for neither. In real maths, we cannot assume open ended ranges are
4130 the same. But, this is computer arithmetic, where numbers are finite.
4131 We can therefore make the transformation of any unbounded range with
4132 the value Z, Z being greater than any representable number. This permits
4133 us to treat unbounded ranges as equal. */
4137 {
4158 }
4161 }
4162 \f
4163 /* Helper routine for make_range. Perform one step for it, return
4164 new expression if the loop should continue or NULL_TREE if it should
4165 stop. */
4167 tree
4171 {
4177 {
4179 /* We can only do something if the range is testing for zero. */
4188 /* We can only do something if the range is testing for zero
4189 and if the second operand is an integer constant. Note that
4190 saying something is "in" the range we make is done by
4191 complementing IN_P since it will set in the initial case of
4192 being not equal to zero; "out" is leaving it alone. */
4199 {
4220 }
4222 /* If this is an unsigned comparison, we also know that EXP is
4223 greater than or equal to zero. We base the range tests we make
4224 on that fact, so we record it here so we can parse existing
4225 range tests. We test arg0_type since often the return type
4226 of, e.g. EQ_EXPR, is boolean. */
4228 {
4232 NULL_TREE))
4237 /* If the high bound is missing, but we have a nonzero low
4238 bound, reverse the range so it goes from zero to the low bound
4239 minus 1. */
4241 {
4246 }
4247 }
4255 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4256 low and high are non-NULL, then normalize will DTRT. */
4259 {
4264 }
4266 /* (-x) IN [a,b] -> x in [-b, -a] */
4278 /* ~ X -> -X - 1 */
4287 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4288 move a constant to the other side. */
4293 /* If EXP is signed, any overflow in the computation is undefined,
4294 so we don't worry about it so long as our computations on
4295 the bounds don't overflow. For unsigned, overflow is defined
4296 and this is exactly the right thing. */
4308 normalize:
4309 /* Check for an unsigned range which has wrapped around the maximum
4310 value thus making n_high < n_low, and normalize it. */
4312 {
4318 /* If the range is of the form +/- [ x+1, x ], we won't
4319 be able to normalize it. But then, it represents the
4320 whole range or the empty set, so make it
4321 +/- [ -, - ]. */
4325 else
4327 }
4328 else
4336 CASE_CONVERT:
4354 /* If we're converting arg0 from an unsigned type, to exp,
4355 a signed type, we will be doing the comparison as unsigned.
4356 The tests above have already verified that LOW and HIGH
4357 are both positive.
4359 So we have to ensure that we will handle large unsigned
4360 values the same way that the current signed bounds treat
4361 negative values. */
4364 {
4365 tree high_positive;
4366 tree equiv_type;
4367 /* For fixed-point modes, we need to pass the saturating flag
4368 as the 2nd parameter. */
4370 equiv_type
4373 else
4374 equiv_type
4377 /* A range without an upper bound is, naturally, unbounded.
4378 Since convert would have cropped a very large value, use
4379 the max value for the destination type. */
4380 high_positive
4387 high_positive),
4390 /* If the low bound is specified, "and" the range with the
4391 range for which the original unsigned value will be
4392 positive. */
4394 {
4397 integer_zero_node),
4398 high_positive))
4402 }
4403 else
4404 {
4405 /* Otherwise, "or" the range with the range of the input
4406 that will be interpreted as negative. */
4409 integer_zero_node),
4410 high_positive))
4414 }
4415 }
4424 }
4425 }
4427 /* Given EXP, a logical expression, set the range it is testing into
4428 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4429 actually being tested. *PLOW and *PHIGH will be made of the same
4430 type as the returned expression. If EXP is not a comparison, we
4431 will most likely not be returning a useful value and range. Set
4432 *STRICT_OVERFLOW_P to true if the return value is only valid
4433 because signed overflow is undefined; otherwise, do not change
4434 *STRICT_OVERFLOW_P. */
4436 tree
4439 {
4447 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4448 and see if we can refine the range. Some of the cases below may not
4449 happen, but it doesn't seem worth worrying about this. We "continue"
4450 the outer loop when we've changed something; otherwise we "break"
4451 the switch, which will "break" the while. */
4457 {
4463 {
4471 }
4480 }
4482 /* If EXP is a constant, we can evaluate whether this is true or false. */
4484 {
4491 }
4495 }
4496 \f
4497 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4498 type, TYPE, return an expression to test if EXP is in (or out of, depending
4499 on IN_P) the range. Return 0 if the test couldn't be created. */
4501 tree
4504 {
4507 #ifdef HAVE_canonicalize_funcptr_for_compare
4508 /* Disable this optimization for function pointer expressions
4509 on targets that require function pointer canonicalization. */
4514 #endif
4517 {
4523 }
4541 {
4543 {
4547 }
4549 }
4551 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4553 {
4557 {
4559 {
4562 etype
4564 else
4567 }
4570 }
4571 }
4573 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4574 This requires wrap-around arithmetics for the type of the expression.
4575 First make sure that arithmetics in this type is valid, then make sure
4576 that it wraps around. */
4582 {
4585 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4586 for the type in question, as we rely on this here. */
4596 else
4598 }
4608 {
4610 {
4615 }
4617 }
4625 }
4626 \f
4627 /* Return the predecessor of VAL in its type, handling the infinite case. */
4629 static tree
4631 {
4637 else
4640 }
4642 /* Return the successor of VAL in its type, handling the infinite case. */
4644 static tree
4646 {
4652 else
4655 }
4657 /* Given two ranges, see if we can merge them into one. Return 1 if we
4658 can, 0 if we can't. Set the output range into the specified parameters. */
4660 bool
4663 {
4667 tree tem;
4677 /* Make range 0 be the range that starts first, or ends last if they
4678 start at the same value. Swap them if it isn't. */
4681 || (lowequal
4684 {
4688 }
4690 /* Now flag two cases, whether the ranges are disjoint or whether the
4691 second range is totally subsumed in the first. Note that the tests
4692 below are simplified by the ones above. */
4698 /* We now have four cases, depending on whether we are including or
4699 excluding the two ranges. */
4701 {
4702 /* If they don't overlap, the result is false. If the second range
4703 is a subset it is the result. Otherwise, the range is from the start
4704 of the second to the end of the first. */
4709 else
4711 }
4714 {
4715 /* If they don't overlap, the result is the first range. If they are
4716 equal, the result is false. If the second range is a subset of the
4717 first, and the ranges begin at the same place, we go from just after
4718 the end of the second range to the end of the first. If the second
4719 range is not a subset of the first, or if it is a subset and both
4720 ranges end at the same place, the range starts at the start of the
4721 first range and ends just before the second range.
4722 Otherwise, we can't describe this as a single range. */
4728 {
4733 {
4734 /* We are in the weird situation where high0 > high1 but
4735 high1 has no successor. Punt. */
4737 }
4738 }
4740 {
4745 {
4746 /* low0 < low1 but low1 has no predecessor. Punt. */
4748 }
4749 }
4750 else
4752 }
4755 {
4756 /* If they don't overlap, the result is the second range. If the second
4757 is a subset of the first, the result is false. Otherwise,
4758 the range starts just after the first range and ends at the
4759 end of the second. */
4764 else
4765 {
4770 {
4771 /* high1 > high0 but high0 has no successor. Punt. */
4773 }
4774 }
4775 }
4777 else
4778 {
4779 /* The case where we are excluding both ranges. Here the complex case
4780 is if they don't overlap. In that case, the only time we have a
4781 range is if they are adjacent. If the second is a subset of the
4782 first, the result is the first. Otherwise, the range to exclude
4783 starts at the beginning of the first range and ends at the end of the
4784 second. */
4786 {
4791 else
4792 {
4793 /* Canonicalize - [min, x] into - [-, x]. */
4796 {
4801 /* FALLTHROUGH */
4814 }
4816 /* Canonicalize - [x, max] into - [x, -]. */
4819 {
4824 /* FALLTHROUGH */
4840 }
4842 /* The ranges might be also adjacent between the maximum and
4843 minimum values of the given type. For
4844 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4845 return + [x + 1, y - 1]. */
4847 {
4854 }
4855 else
4857 }
4858 }
4861 else
4863 }
4867 }
4868 \f
4870 /* Subroutine of fold, looking inside expressions of the form
4871 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4872 of the COND_EXPR. This function is being used also to optimize
4873 A op B ? C : A, by reversing the comparison first.
4875 Return a folded expression whose code is not a COND_EXPR
4876 anymore, or NULL_TREE if no folding opportunity is found. */
4878 static tree
4881 {
4886 tree tem;
4891 /* If we have A op 0 ? A : -A, consider applying the following
4892 transformations:
4894 A == 0? A : -A same as -A
4895 A != 0? A : -A same as A
4896 A >= 0? A : -A same as abs (A)
4897 A > 0? A : -A same as abs (A)
4898 A <= 0? A : -A same as -abs (A)
4899 A < 0? A : -A same as -abs (A)
4901 None of these transformations work for modes with signed
4902 zeros. If A is +/-0, the first two transformations will
4903 change the sign of the result (from +0 to -0, or vice
4904 versa). The last four will fix the sign of the result,
4905 even though the original expressions could be positive or
4906 negative, depending on the sign of A.
4908 Note that all these transformations are correct if A is
4909 NaN, since the two alternatives (A and -A) are also NaNs. */
4916 /* In the case that A is of the form X-Y, '-A' (arg2) may
4917 have already been folded to Y-X, check for that. */
4925 {
4939 /* Fall through. */
4961 }
4963 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4964 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4965 both transformations are correct when A is NaN: A != 0
4966 is then true, and A == 0 is false. */
4970 {
4975 }
4977 /* Try some transformations of A op B ? A : B.
4979 A == B? A : B same as B
4980 A != B? A : B same as A
4981 A >= B? A : B same as max (A, B)
4982 A > B? A : B same as max (B, A)
4983 A <= B? A : B same as min (A, B)
4984 A < B? A : B same as min (B, A)
4986 As above, these transformations don't work in the presence
4987 of signed zeros. For example, if A and B are zeros of
4988 opposite sign, the first two transformations will change
4989 the sign of the result. In the last four, the original
4990 expressions give different results for (A=+0, B=-0) and
4991 (A=-0, B=+0), but the transformed expressions do not.
4993 The first two transformations are correct if either A or B
4994 is a NaN. In the first transformation, the condition will
4995 be false, and B will indeed be chosen. In the case of the
4996 second transformation, the condition A != B will be true,
4997 and A will be chosen.
4999 The conversions to max() and min() are not correct if B is
5000 a number and A is not. The conditions in the original
5001 expressions will be false, so all four give B. The min()
5002 and max() versions would give a NaN instead. */
5005 /* Avoid these transformations if the COND_EXPR may be used
5006 as an lvalue in the C++ front-end. PR c++/19199. */
5007 && (in_gimple_form
5013 {
5018 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5020 {
5024 }
5027 {
5036 /* In C++ a ?: expression can be an lvalue, so put the
5037 operand which will be used if they are equal first
5038 so that we can convert this back to the
5039 corresponding COND_EXPR. */
5041 {
5050 }
5057 {
5066 }
5081 }
5082 }
5084 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5085 we might still be able to simplify this. For example,
5086 if C1 is one less or one more than C2, this might have started
5087 out as a MIN or MAX and been transformed by this function.
5088 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5094 {
5098 /* We can replace A with C1 in this case. */
5103 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5104 MIN_EXPR, to preserve the signedness of the comparison. */
5106 OEP_ONLY_CONST)
5110 OEP_ONLY_CONST))
5111 {
5114 arg2));
5117 }
5121 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5122 as above. */
5124 OEP_ONLY_CONST)
5128 OEP_ONLY_CONST))
5129 {
5132 arg2));
5135 }
5139 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5140 MAX_EXPR, to preserve the signedness of the comparison. */
5142 OEP_ONLY_CONST)
5146 OEP_ONLY_CONST))
5147 {
5150 arg2));
5152 }
5156 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5158 OEP_ONLY_CONST)
5162 OEP_ONLY_CONST))
5163 {
5166 arg2));
5168 }
5174 }
5177 }
5180 \f
5181 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5182 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5183 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5184 false) >= 2)
5185 #endif
5187 /* EXP is some logical combination of boolean tests. See if we can
5188 merge it into some range test. Return the new tree if so. */
5190 static tree
5193 {
5209 /* If this is an OR operation, invert both sides; we will invert
5210 again at the end. */
5214 /* If both expressions are the same, if we can merge the ranges, and we
5215 can build the range test, return it or it inverted. If one of the
5216 ranges is always true or always false, consider it to be the same
5217 expression as the other. */
5225 {
5229 }
5231 /* On machines where the branch cost is expensive, if this is a
5232 short-circuited branch and the underlying object on both sides
5233 is the same, make a non-short-circuit operation. */
5239 {
5240 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5241 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5242 which cases we can't do this. */
5250 {
5259 {
5262 WARN_STRICT_OVERFLOW_COMPARISON);
5266 }
5267 }
5268 }
5271 }
5272 \f
5273 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5274 bit value. Arrange things so the extra bits will be set to zero if and
5275 only if C is signed-extended to its full width. If MASK is nonzero,
5276 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5278 static tree
5280 {
5283 tree temp;
5288 /* We work by getting just the sign bit into the low-order bit, then
5289 into the high-order bit, then sign-extend. We then XOR that value
5290 with C. */
5293 /* We must use a signed type in order to get an arithmetic right shift.
5294 However, we must also avoid introducing accidental overflows, so that
5295 a subsequent call to integer_zerop will work. Hence we must
5296 do the type conversion here. At this point, the constant is either
5297 zero or one, and the conversion to a signed type can never overflow.
5298 We could get an overflow if this conversion is done anywhere else. */
5307 /* If necessary, convert the type back to match the type of C. */
5312 }
5313 \f
5314 /* For an expression that has the form
5315 (A && B) || ~B
5316 or
5317 (A || B) && ~B,
5318 we can drop one of the inner expressions and simplify to
5319 A || ~B
5320 or
5321 A && ~B
5322 LOC is the location of the resulting expression. OP is the inner
5323 logical operation; the left-hand side in the examples above, while CMPOP
5324 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5325 removing a condition that guards another, as in
5326 (A != NULL && A->...) || A == NULL
5327 which we must not transform. If RHS_ONLY is true, only eliminate the
5328 right-most operand of the inner logical operation. */
5330 static tree
5333 {
5351 {
5354 {
5357 }
5358 }
5360 {
5363 {
5366 }
5367 }
5382 }
5384 /* Find ways of folding logical expressions of LHS and RHS:
5385 Try to merge two comparisons to the same innermost item.
5386 Look for range tests like "ch >= '0' && ch <= '9'".
5387 Look for combinations of simple terms on machines with expensive branches
5388 and evaluate the RHS unconditionally.
5390 For example, if we have p->a == 2 && p->b == 4 and we can make an
5391 object large enough to span both A and B, we can do this with a comparison
5392 against the object ANDed with the a mask.
5394 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5395 operations to do this with one comparison.
5397 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5398 function and the one above.
5400 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5401 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5403 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5404 two operands.
5406 We return the simplified tree or 0 if no optimization is possible. */
5408 static tree
5411 {
5412 /* If this is the "or" of two comparisons, we can do something if
5413 the comparisons are NE_EXPR. If this is the "and", we can do something
5414 if the comparisons are EQ_EXPR. I.e.,
5415 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5417 WANTED_CODE is this operation code. For single bit fields, we can
5418 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5419 comparison for one-bit fields. */
5439 /* Start by getting the comparison codes. Fail if anything is volatile.
5440 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5441 it were surrounded with a NE_EXPR. */
5450 {
5454 }
5457 {
5461 }
5472 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5475 {
5478 {
5483 }
5486 {
5492 }
5493 }
5498 /* If the RHS can be evaluated unconditionally and its operands are
5499 simple, it wins to evaluate the RHS unconditionally on machines
5500 with expensive branches. In this case, this isn't a comparison
5501 that can be merged. */
5508 {
5509 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5520 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5530 }
5532 /* See if the comparisons can be merged. Then get all the parameters for
5533 each side. */
5557 /* It must be true that the inner operation on the lhs of each
5558 comparison must be the same if we are to be able to do anything.
5559 Then see if we have constants. If not, the same must be true for
5560 the rhs's. */
5571 else
5574 /* If either comparison code is not correct for our logical operation,
5575 fail. However, we can convert a one-bit comparison against zero into
5576 the opposite comparison against that bit being set in the field. */
5580 {
5582 {
5583 /* Make the left operand unsigned, since we are only interested
5584 in the value of one bit. Otherwise we are doing the wrong
5585 thing below. */
5588 }
5589 else
5591 }
5593 /* This is analogous to the code for l_const above. */
5595 {
5597 {
5600 }
5601 else
5603 }
5605 /* See if we can find a mode that contains both fields being compared on
5606 the left. If we can't, fail. Otherwise, update all constants and masks
5607 to be relative to a field of that size. */
5612 volatilep);
5622 {
5625 }
5633 {
5640 {
5644 }
5645 }
5647 {
5654 {
5658 }
5659 }
5661 /* If the right sides are not constant, do the same for it. Also,
5662 disallow this optimization if a size or signedness mismatch occurs
5663 between the left and right sides. */
5665 {
5668 /* Make sure the two fields on the right
5669 correspond to the left without being swapped. */
5677 volatilep);
5687 {
5690 }
5699 /* Make a mask that corresponds to both fields being compared.
5700 Do this for both items being compared. If the operands are the
5701 same size and the bits being compared are in the same position
5702 then we can do this by masking both and comparing the masked
5703 results. */
5707 {
5719 }
5721 /* There is still another way we can do something: If both pairs of
5722 fields being compared are adjacent, we may be able to make a wider
5723 field containing them both.
5725 Note that we still must mask the lhs/rhs expressions. Furthermore,
5726 the mask must be shifted to account for the shift done by
5727 make_bit_field_ref. */
5732 {
5733 tree type;
5747 /* Convert to the smaller type before masking out unwanted bits. */
5750 {
5752 {
5756 }
5758 {
5762 }
5763 }
5772 }
5775 }
5777 /* Handle the case of comparisons with constants. If there is something in
5778 common between the masks, those bits of the constants must be the same.
5779 If not, the condition is always false. Test for this to avoid generating
5780 incorrect code below. */
5785 {
5787 {
5790 }
5791 else
5792 {
5795 }
5796 }
5798 /* Construct the expression we will return. First get the component
5799 reference we will make. Unless the mask is all ones the width of
5800 that field, perform the mask operation. Then compare with the
5801 merged constant. */
5811 }
5812 \f
5813 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5814 constant. */
5816 static tree
5819 {
5822 tree comp_const;
5823 tree minmax_const;
5825 tree inner;
5836 /* If something does not permit us to optimize, return the original tree. */
5844 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5845 and GT_EXPR, doing the rest with recursive calls using logical
5846 simplifications. */
5848 {
5850 {
5851 tree tem
5858 }
5861 return
5863 optimize_minmax_comparison
5865 optimize_minmax_comparison
5870 /* MAX (X, 0) == 0 -> X <= 0 */
5874 /* MAX (X, 0) == 5 -> X == 5 */
5878 /* MAX (X, 0) == -1 -> false */
5882 /* MIN (X, 0) == 0 -> X >= 0 */
5886 /* MIN (X, 0) == 5 -> false */
5889 else
5890 /* MIN (X, 0) == -1 -> X == -1 */
5895 /* MAX (X, 0) > 0 -> X > 0
5896 MAX (X, 0) > 5 -> X > 5 */
5900 /* MAX (X, 0) > -1 -> true */
5904 /* MIN (X, 0) > 0 -> false
5905 MIN (X, 0) > 5 -> false */
5908 else
5909 /* MIN (X, 0) > -1 -> X > -1 */
5914 }
5915 }
5916 \f
5917 /* T is an integer expression that is being multiplied, divided, or taken a
5918 modulus (CODE says which and what kind of divide or modulus) by a
5919 constant C. See if we can eliminate that operation by folding it with
5920 other operations already in T. WIDE_TYPE, if non-null, is a type that
5921 should be used for the computation if wider than our type.
5923 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5924 (X * 2) + (Y * 4). We must, however, be assured that either the original
5925 expression would not overflow or that overflow is undefined for the type
5926 in the language in question.
5928 If we return a non-null expression, it is an equivalent form of the
5929 original computation, but need not be in the original type.
5931 We set *STRICT_OVERFLOW_P to true if the return values depends on
5932 signed overflow being undefined. Otherwise we do not change
5933 *STRICT_OVERFLOW_P. */
5935 static tree
5938 {
5939 /* To avoid exponential search depth, refuse to allow recursion past
5940 three levels. Beyond that (1) it's highly unlikely that we'll find
5941 something interesting and (2) we've probably processed it before
5942 when we built the inner expression. */
5945 tree ret;
5950 depth++;
5952 depth--;
5955 }
5957 static tree
5960 {
5971 /* Don't deal with constants of zero here; they confuse the code below. */
5981 /* Note that we need not handle conditional operations here since fold
5982 already handles those cases. So just do arithmetic here. */
5984 {
5986 /* For a constant, we can always simplify if we are a multiply
5987 or (for divide and modulus) if it is a multiple of our constant. */
5995 /* If op0 is an expression ... */
6001 /* ... and has wrapping overflow, and its type is smaller
6002 than ctype, then we cannot pass through as widening. */
6007 /* ... or this is a truncation (t is narrower than op0),
6008 then we cannot pass through this narrowing. */
6011 /* ... or signedness changes for division or modulus,
6012 then we cannot pass through this conversion. */
6016 /* ... or has undefined overflow while the converted to
6017 type has not, we cannot do the operation in the inner type
6018 as that would introduce undefined overflow. */
6024 /* Pass the constant down and see if we can make a simplification. If
6025 we can, replace this expression with the inner simplification for
6026 possible later conversion to our or some other type. */
6031 code == MULT_EXPR
6033 strict_overflow_p))))
6038 /* If widening the type changes it from signed to unsigned, then we
6039 must avoid building ABS_EXPR itself as unsigned. */
6041 {
6045 {
6048 }
6050 }
6051 /* If the constant is negative, we cannot simplify this. */
6054 /* FALLTHROUGH */
6056 /* For division and modulus, type can't be unsigned, as e.g.
6057 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6058 For signed types, even with wrapping overflow, this is fine. */
6067 /* If widening the type changes the signedness, then we can't perform
6068 this optimization as that changes the result. */
6072 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6078 {
6085 }
6089 /* If the second operand is constant, this is a multiplication
6090 or floor division, by a power of two, so we can treat it that
6091 way unless the multiplier or divisor overflows. Signed
6092 left-shift overflow is implementation-defined rather than
6093 undefined in C90, so do not convert signed left shift into
6094 multiplication. */
6097 /* const_binop may not detect overflow correctly,
6098 so check for it explicitly here. */
6102 size_one_node,
6103 op1)))
6107 ctype,
6109 t1),
6114 /* See if we can eliminate the operation on both sides. If we can, we
6115 can return a new PLUS or MINUS. If we can't, the only remaining
6116 cases where we can do anything are if the second operand is a
6117 constant. */
6123 /* If not multiplication, we can only do this if both operands
6124 are divisible by c. */
6127 {
6132 }
6134 /* If this was a subtraction, negate OP1 and set it to be an addition.
6135 This simplifies the logic below. */
6137 {
6139 /* If OP1 was not easily negatable, the constant may be OP0. */
6141 {
6148 }
6149 }
6154 /* If either OP1 or C are negative, this optimization is not safe for
6155 some of the division and remainder types while for others we need
6156 to change the code. */
6158 {
6166 }
6168 /* If it's a multiply or a division/modulus operation of a multiple
6169 of our constant, do the operation and verify it doesn't overflow. */
6172 {
6175 /* We allow the constant to overflow with wrapping semantics. */
6179 }
6180 else
6183 /* If we have an unsigned type, we cannot widen the operation since it
6184 will change the result if the original computation overflowed. */
6188 /* If we were able to eliminate our operation from the first side,
6189 apply our operation to the second side and reform the PLUS. */
6193 /* The last case is if we are a multiply. In that case, we can
6194 apply the distributive law to commute the multiply and addition
6195 if the multiplication of the constants doesn't overflow
6196 and overflow is defined. With undefined overflow
6197 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6203 op1);
6208 /* We have a special case here if we are doing something like
6209 (C * 8) % 4 since we know that's zero. */
6212 /* If the multiplication can overflow we cannot optimize this. */
6216 {
6219 }
6221 /* ... fall through ... */
6225 /* If we can extract our operation from the LHS, do so and return a
6226 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6227 do something only if the second operand is a constant. */
6241 /* If these are the same operation types, we can associate them
6242 assuming no overflow. */
6244 {
6256 }
6258 /* If these operations "cancel" each other, we have the main
6259 optimizations of this pass, which occur when either constant is a
6260 multiple of the other, in which case we replace this with either an
6261 operation or CODE or TCODE.
6263 If we have an unsigned type, we cannot do this since it will change
6264 the result if the original computation overflowed. */
6271 {
6273 {
6280 }
6282 {
6289 }
6290 }
6295 }
6298 }
6299 \f
6300 /* Return a node which has the indicated constant VALUE (either 0 or
6301 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6302 and is of the indicated TYPE. */
6304 tree
6306 {
6315 else
6317 }
6320 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6321 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6322 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6323 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6324 COND is the first argument to CODE; otherwise (as in the example
6325 given here), it is the second argument. TYPE is the type of the
6326 original expression. Return NULL_TREE if no simplification is
6327 possible. */
6329 static tree
6334 {
6344 {
6348 /* If this operand throws an expression, then it does not make
6349 sense to try to perform a logical or arithmetic operation
6350 involving it. */
6355 }
6356 else
6357 {
6362 }
6367 /* This transformation is only worthwhile if we don't have to wrap ARG
6368 in a SAVE_EXPR and the operation can be simplified without recursing
6369 on at least one of the branches once its pushed inside the COND_EXPR. */
6378 {
6382 else
6384 }
6386 {
6390 else
6392 }
6394 /* Check that we have simplified at least one of the branches. */
6399 }
6401 \f
6402 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6404 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6405 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6406 ADDEND is the same as X.
6408 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6409 and finite. The problematic cases are when X is zero, and its mode
6410 has signed zeros. In the case of rounding towards -infinity,
6411 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6412 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6414 bool
6416 {
6420 /* Don't allow the fold with -fsignaling-nans. */
6424 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6428 /* In a vector or complex, we would need to check the sign of all zeros. */
6432 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6436 /* The mode has signed zeros, and we have to honor their sign.
6437 In this situation, there is only one case we can return true for.
6438 X - 0 is the same as X unless rounding towards -infinity is
6439 supported. */
6441 }
6443 /* Subroutine of fold() that checks comparisons of built-in math
6444 functions against real constants.
6446 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6447 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6448 is the type of the result and ARG0 and ARG1 are the operands of the
6449 comparison. ARG1 must be a TREE_REAL_CST.
6451 The function returns the constant folded tree if a simplification
6452 can be made, and NULL_TREE otherwise. */
6454 static tree
6458 {
6459 REAL_VALUE_TYPE c;
6462 {
6468 {
6469 /* sqrt(x) < y is always false, if y is negative. */
6473 /* sqrt(x) > y is always true, if y is negative and we
6474 don't care about NaNs, i.e. negative values of x. */
6478 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6481 }
6483 {
6484 REAL_VALUE_TYPE c2;
6490 {
6491 /* sqrt(x) > y is x == +Inf, when y is very large. */
6496 /* sqrt(x) > y is always false, when y is very large
6497 and we don't care about infinities. */
6499 }
6501 /* sqrt(x) > c is the same as x > c*c. */
6504 }
6506 {
6507 REAL_VALUE_TYPE c2;
6513 {
6514 /* sqrt(x) < y is always true, when y is a very large
6515 value and we don't care about NaNs or Infinities. */
6519 /* sqrt(x) < y is x != +Inf when y is very large and we
6520 don't care about NaNs. */
6525 /* sqrt(x) < y is x >= 0 when y is very large and we
6526 don't care about Infinities. */
6531 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6536 dconst0)),
6539 c2)));
6540 }
6542 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6547 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6552 dconst0)),
6555 c2)));
6556 }
6557 }
6560 }
6562 /* Subroutine of fold() that optimizes comparisons against Infinities,
6563 either +Inf or -Inf.
6565 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6566 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6567 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6569 The function returns the constant folded tree if a simplification
6570 can be made, and NULL_TREE otherwise. */
6572 static tree
6575 {
6576 machine_mode mode;
6577 REAL_VALUE_TYPE max;
6578 tree temp;
6583 /* For negative infinity swap the sense of the comparison. */
6589 {
6591 /* x > +Inf is always false, if with ignore sNANs. */
6597 /* x <= +Inf is always true, if we don't case about NaNs. */
6601 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6607 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6613 /* x < +Inf is always equal to x <= DBL_MAX. */
6619 /* x != +Inf is always equal to !(x > DBL_MAX). */
6631 }
6634 }
6636 /* Subroutine of fold() that optimizes comparisons of a division by
6637 a nonzero integer constant against an integer constant, i.e.
6638 X/C1 op C2.
6640 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6641 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6642 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6644 The function returns the constant folded tree if a simplification
6645 can be made, and NULL_TREE otherwise. */
6647 static tree
6650 {
6658 /* We have to do this the hard way to detect unsigned overflow.
6659 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6665 {
6670 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6674 }
6676 {
6680 {
6699 }
6700 }
6701 else
6702 {
6703 /* A negative divisor reverses the relational operators. */
6709 {
6728 }
6729 }
6732 {
6753 {
6756 }
6761 {
6764 }
6769 {
6772 }
6777 {
6780 }
6785 }
6788 }
6791 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6792 equality/inequality test, then return a simplified form of the test
6793 using a sign testing. Otherwise return NULL. TYPE is the desired
6794 result type. */
6796 static tree
6799 tree result_type)
6800 {
6801 /* If this is testing a single bit, we can optimize the test. */
6805 {
6806 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6807 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6811 /* This is only a win if casting to a signed type is cheap,
6812 i.e. when arg00's type is not a partial mode. */
6815 {
6818 result_type,
6821 }
6822 }
6825 }
6827 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6828 equality/inequality test, then return a simplified form of
6829 the test using shifts and logical operations. Otherwise return
6830 NULL. TYPE is the desired result type. */
6832 tree
6835 {
6836 /* If this is testing a single bit, we can optimize the test. */
6840 {
6849 /* First, see if we can fold the single bit test into a sign-bit
6850 test. */
6852 result_type);
6856 /* Otherwise we have (A & C) != 0 where C is a single bit,
6857 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6858 Similarly for (A & C) == 0. */
6860 /* If INNER is a right shift of a constant and it plus BITNUM does
6861 not overflow, adjust BITNUM and INNER. */
6867 {
6870 }
6872 /* If we are going to be able to omit the AND below, we must do our
6873 operations as unsigned. If we must use the AND, we have a choice.
6874 Normally unsigned is faster, but for some machines signed is. */
6875 #ifdef LOAD_EXTEND_OP
6878 #else
6880 #endif
6896 /* Put the AND last so it can combine with more things. */
6899 /* Make sure to return the proper type. */
6903 }
6905 }
6907 /* Check whether we are allowed to reorder operands arg0 and arg1,
6908 such that the evaluation of arg1 occurs before arg0. */
6910 static bool
6912 {
6919 }
6921 /* Test whether it is preferable two swap two operands, ARG0 and
6922 ARG1, for example because ARG0 is an integer constant and ARG1
6923 isn't. If REORDER is true, only recommend swapping if we can
6924 evaluate the operands in reverse order. */
6926 bool
6928 {
6946 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6947 for commutative and comparison operators. Ensuring a canonical
6948 form allows the optimizers to find additional redundancies without
6949 having to explicitly check for both orderings. */
6955 /* Put SSA_NAMEs last. */
6961 /* Put variables last. */
6968 }
6970 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6971 ARG0 is extended to a wider type. */
6973 static tree
6976 {
6978 tree arg1_unw;
6987 #ifdef HAVE_canonicalize_funcptr_for_compare
6988 /* Disable this optimization if we're casting a function pointer
6989 type on targets that require function pointer canonicalization. */
6994 #endif
7001 /* If possible, express the comparison in the shorter mode. */
7021 /* If we are comparing with the integer that does not fit into the range
7022 of the shorter type, the result is known. */
7033 {
7060 }
7063 }
7065 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7066 ARG0 just the signedness is changed. */
7068 static tree
7071 {
7072 tree arg0_inner;
7082 #ifdef HAVE_canonicalize_funcptr_for_compare
7083 /* Disable this optimization if we're casting a function pointer
7084 type on targets that require function pointer canonicalization. */
7089 #endif
7110 else
7114 }
7117 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7118 means A >= Y && A != MAX, but in this case we know that
7119 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7121 static tree
7123 {
7130 else
7139 {
7142 }
7144 {
7147 }
7148 else
7155 {
7156 /* Convert the pointer types into integer before taking the difference. */
7160 }
7161 else
7168 }
7170 /* Fold a sum or difference of at least one multiplication.
7171 Returns the folded tree or NULL if no simplification could be made. */
7173 static tree
7176 {
7180 /* (A * C) +- (B * C) -> (A+-B) * C.
7181 (A * C) +- A -> A * (C+-1).
7182 We are most concerned about the case where C is a constant,
7183 but other combinations show up during loop reduction. Since
7184 it is not difficult, try all four possibilities. */
7187 {
7190 }
7192 {
7195 }
7196 else
7197 {
7198 /* We cannot generate constant 1 for fract. */
7203 }
7205 {
7208 }
7210 {
7212 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7213 the purpose of this canonicalization. */
7217 {
7220 }
7221 else
7223 }
7224 else
7225 {
7226 /* We cannot generate constant 1 for fract. */
7231 }
7243 /* No identical multiplicands; see if we can find a common
7244 power-of-two factor in non-power-of-two multiplies. This
7245 can help in multi-dimensional array access. */
7248 {
7251 tree maybe_same;
7255 /* Move min of absolute values to int11. */
7257 {
7262 }
7263 else
7267 /* The remainder should not be a constant, otherwise we
7268 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7269 increased the number of multiplications necessary. */
7271 {
7279 }
7280 }
7290 }
7292 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7293 specified by EXPR into the buffer PTR of length LEN bytes.
7294 Return the number of bytes placed in the buffer, or zero
7295 upon failure. */
7297 static int
7299 {
7313 {
7315 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7316 number of bytes. */
7320 {
7327 else
7329 }
7330 else
7335 }
7337 }
7340 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7341 specified by EXPR into the buffer PTR of length LEN bytes.
7342 Return the number of bytes placed in the buffer, or zero
7343 upon failure. */
7345 static int
7347 {
7351 FIXED_VALUE_TYPE value;
7367 }
7370 /* Subroutine of native_encode_expr. Encode the REAL_CST
7371 specified by EXPR into the buffer PTR of length LEN bytes.
7372 Return the number of bytes placed in the buffer, or zero
7373 upon failure. */
7375 static int
7377 {
7383 /* There are always 32 bits in each long, no matter the size of
7384 the hosts long. We handle floating point representations with
7385 up to 192 bits. */
7399 {
7404 {
7411 else
7413 }
7414 else
7420 }
7422 }
7424 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7425 specified by EXPR into the buffer PTR of length LEN bytes.
7426 Return the number of bytes placed in the buffer, or zero
7427 upon failure. */
7429 static int
7431 {
7433 tree part;
7448 }
7451 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7452 specified by EXPR into the buffer PTR of length LEN bytes.
7453 Return the number of bytes placed in the buffer, or zero
7454 upon failure. */
7456 static int
7458 {
7468 {
7470 {
7473 }
7484 }
7486 }
7489 /* Subroutine of native_encode_expr. Encode the STRING_CST
7490 specified by EXPR into the buffer PTR of length LEN bytes.
7491 Return the number of bytes placed in the buffer, or zero
7492 upon failure. */
7494 static int
7496 {
7498 HOST_WIDE_INT total_bytes;
7512 {
7515 {
7518 }
7521 }
7522 else
7525 }
7528 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7529 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7530 buffer PTR of length LEN bytes. If OFF is not -1 then start
7531 the encoding at byte offset OFF and encode at most LEN bytes.
7532 Return the number of bytes placed in the buffer, or zero upon failure. */
7534 int
7536 {
7538 {
7559 }
7560 }
7563 /* Subroutine of native_interpret_expr. Interpret the contents of
7564 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7565 If the buffer cannot be interpreted, return NULL_TREE. */
7567 static tree
7569 {
7579 }
7582 /* Subroutine of native_interpret_expr. Interpret the contents of
7583 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7584 If the buffer cannot be interpreted, return NULL_TREE. */
7586 static tree
7588 {
7590 double_int result;
7591 FIXED_VALUE_TYPE fixed_value;
7601 }
7604 /* Subroutine of native_interpret_expr. Interpret the contents of
7605 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7606 If the buffer cannot be interpreted, return NULL_TREE. */
7608 static tree
7610 {
7615 /* There are always 32 bits in each long, no matter the size of
7616 the hosts long. We handle floating point representations with
7617 up to 192 bits. */
7618 REAL_VALUE_TYPE r;
7629 {
7632 {
7639 else
7641 }
7642 else
7647 }
7651 }
7654 /* Subroutine of native_interpret_expr. Interpret the contents of
7655 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7656 If the buffer cannot be interpreted, return NULL_TREE. */
7658 static tree
7660 {
7675 }
7678 /* Subroutine of native_interpret_expr. Interpret the contents of
7679 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7680 If the buffer cannot be interpreted, return NULL_TREE. */
7682 static tree
7684 {
7697 {
7702 }
7704 }
7707 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7708 the buffer PTR of length LEN as a constant of type TYPE. For
7709 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7710 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7711 return NULL_TREE. */
7713 tree
7715 {
7717 {
7739 }
7740 }
7742 /* Returns true if we can interpret the contents of a native encoding
7743 as TYPE. */
7745 static bool
7747 {
7749 {
7762 }
7763 }
7765 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7766 TYPE at compile-time. If we're unable to perform the conversion
7767 return NULL_TREE. */
7769 static tree
7771 {
7772 /* We support up to 512-bit values (for V8DFmode). */
7776 /* Check that the host and target are sane. */
7785 }
7787 /* Build an expression for the address of T. Folds away INDIRECT_REF
7788 to avoid confusing the gimplify process. */
7790 tree
7792 {
7793 /* The size of the object is not relevant when talking about its address. */
7798 {
7803 }
7813 {
7818 }
7819 else
7823 }
7825 /* Build an expression for the address of T. */
7827 tree
7829 {
7833 }
7835 /* Fold a unary expression of code CODE and type TYPE with operand
7836 OP0. Return the folded expression if folding is successful.
7837 Otherwise, return NULL_TREE. */
7839 tree
7841 {
7842 tree tem;
7843 tree arg0;
7851 {
7854 {
7855 /* Don't use STRIP_NOPS, because signedness of argument type
7856 matters. */
7858 }
7859 else
7860 {
7861 /* Strip any conversions that don't change the mode. This
7862 is safe for every expression, except for a comparison
7863 expression because its signedness is derived from its
7864 operands.
7866 Note that this is done as an internal manipulation within
7867 the constant folder, in order to find the simplest
7868 representation of the arguments so that their form can be
7869 studied. In any cases, the appropriate type conversions
7870 should be put back in the tree that will get out of the
7871 constant folder. */
7873 }
7876 {
7879 {
7883 }
7884 }
7885 }
7892 {
7899 {
7913 /* If this was a conversion, and all we did was to move into
7914 inside the COND_EXPR, bring it back out. But leave it if
7915 it is a conversion from integer to integer and the
7916 result precision is no wider than a word since such a
7917 conversion is cheap and may be optimized away by combine,
7918 while it couldn't if it were outside the COND_EXPR. Then return
7919 so we don't get into an infinite recursion loop taking the
7920 conversion out and then back in. */
7932 && (INTEGRAL_TYPE_P
7945 }
7946 }
7949 {
7955 CASE_CONVERT:
7959 {
7960 /* If we have (type) (a CMP b) and type is an integral type, return
7961 new expression involving the new type. Canonicalize
7962 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7963 non-integral type.
7964 Do not fold the result as that would not simplify further, also
7965 folding again results in recursions. */
7975 }
7977 /* Handle (T *)&A.B.C for A being of type T and B and C
7978 living at offset zero. This occurs frequently in
7979 C++ upcasting and then accessing the base. */
7983 {
7985 tree offset;
7986 machine_mode mode;
7991 /* If the reference was to a (constant) zero offset, we can use
7992 the address of the base if it has the same base type
7993 as the result type and the pointer type is unqualified. */
8000 }
8004 /* Detect assigning a bitfield. */
8006 && DECL_BIT_FIELD
8008 {
8009 /* Don't leave an assignment inside a conversion
8010 unless assigning a bitfield. */
8012 /* First do the assignment, then return converted constant. */
8017 }
8019 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8020 constants (if x has signed type, the sign bit cannot be set
8021 in c). This folds extension into the BIT_AND_EXPR.
8022 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8023 very likely don't have maximal range for their precision and this
8024 transformation effectively doesn't preserve non-maximal ranges. */
8028 {
8039 <= HOST_BITS_PER_WIDE_INT
8041 {
8045 cst &= HOST_WIDE_INT_M1U
8048 #ifdef LOAD_EXTEND_OP
8050 && !flag_syntax_only
8053 {
8057 }
8058 #endif
8059 }
8061 {
8066 }
8067 }
8069 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8070 when one of the new casts will fold away. Conservatively we assume
8071 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8078 {
8082 return fold_build_pointer_plus_loc
8084 }
8086 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8087 of the same precision, and X is an integer type not narrower than
8088 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8094 {
8100 }
8102 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8103 type of X and Y (integer types only). */
8108 {
8109 /* Be careful not to introduce new overflows. */
8110 tree mult_type;
8113 else
8117 {
8124 }
8125 }
8143 /* Convert fabs((double)float) into (double)fabsf(float). */
8146 {
8152 targ0));
8153 }
8154 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8158 /* Strip sign ops from argument. */
8160 {
8165 }
8172 {
8178 }
8184 /* Convert ~ (-A) to A - 1. */
8189 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8195 {
8196 /* Perform the negation in ARG0's type and only then convert
8197 to TYPE as to avoid introducing undefined behavior. */
8202 }
8203 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8222 /* Note that the operand of this must be an int
8223 and its values must be 0 or 1.
8224 ("true" is a fixed value perhaps depending on the language,
8225 but we don't handle values other than 1 correctly yet.) */
8235 {
8243 }
8245 {
8250 }
8252 {
8256 {
8265 }
8266 }
8273 {
8281 }
8283 {
8287 }
8289 {
8293 {
8302 }
8303 }
8307 /* Fold *&X to X if X is an lvalue. */
8309 {
8316 }
8322 }
8325 /* If the operation was a conversion do _not_ mark a resulting constant
8326 with TREE_OVERFLOW if the original constant was not. These conversions
8327 have implementation defined behavior and retaining the TREE_OVERFLOW
8328 flag here would confuse later passes such as VRP. */
8329 tree
8332 {
8341 }
8343 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8344 operands OP0 and OP1. LOC is the location of the resulting expression.
8345 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8346 Return the folded expression if folding is successful. Otherwise,
8347 return NULL_TREE. */
8348 static tree
8351 {
8352 tree tem;
8354 /* We only do these simplifications if we are optimizing. */
8358 /* Check for things like (A || B) && (A || C). We can convert this
8359 to A || (B && C). Note that either operator can be any of the four
8360 truth and/or operations and the transformation will still be
8361 valid. Also note that we only care about order for the
8362 ANDIF and ORIF operators. If B contains side effects, this
8363 might change the truth-value of A. */
8370 {
8390 /* This case if tricky because we must either have commutative
8391 operators or else A10 must not have side-effects. */
8397 a01);
8398 }
8400 /* See if we can build a range comparison. */
8406 {
8410 }
8414 {
8418 }
8420 /* Check for the possibility of merging component references. If our
8421 lhs is another similar operation, try to merge its rhs with our
8422 rhs. Then try to merge our lhs and rhs. */
8436 {
8443 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8444 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8445 We don't want to pack more than two leafs to a non-IF AND/OR
8446 expression.
8447 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8448 equal to IF-CODE, then we don't want to add right-hand operand.
8449 If the inner right-hand side of left-hand operand has
8450 side-effects, or isn't simple, then we can't add to it,
8451 as otherwise we might destroy if-sequence. */
8454 /* Needed for sequence points to handle trappings, and
8455 side-effects. */
8457 {
8459 arg1);
8461 tem);
8462 }
8463 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8464 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8467 /* Needed for sequence points to handle trappings, and
8468 side-effects. */
8470 {
8475 }
8476 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8477 into (A OR B).
8478 For sequence point consistancy, we need to check for trapping,
8479 and side-effects. */
8483 }
8486 }
8488 /* Fold a binary expression of code CODE and type TYPE with operands
8489 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8490 Return the folded expression if folding is successful. Otherwise,
8491 return NULL_TREE. */
8493 static tree
8495 {
8502 else
8505 /* MIN (MAX (a, b), b) == b. */
8510 /* MIN (MAX (b, a), b) == b. */
8516 /* MIN (a, MAX (a, b)) == a. */
8522 /* MIN (a, MAX (b, a)) == a. */
8529 }
8531 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8532 by changing CODE to reduce the magnitude of constants involved in
8533 ARG0 of the comparison.
8534 Returns a canonicalized comparison tree if a simplification was
8535 possible, otherwise returns NULL_TREE.
8536 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8537 valid if signed overflow is undefined. */
8539 static tree
8543 {
8549 /* Match A +- CST code arg1 and CST code arg1. We can change the
8550 first form only if overflow is undefined. */
8553 /* In principle pointers also have undefined overflow behavior,
8554 but that causes problems elsewhere. */
8562 /* Identify the constant in arg0 and its sign. */
8565 else
8569 /* Overflowed constants and zero will cause problems. */
8574 /* See if we can reduce the magnitude of the constant in
8575 arg0 by changing the comparison code. */
8577 {
8578 /* CST <= arg1 -> CST-1 < arg1. */
8581 /* -CST < arg1 -> -CST-1 <= arg1. */
8584 /* CST > arg1 -> CST-1 >= arg1. */
8587 /* -CST >= arg1 -> -CST-1 > arg1. */
8590 else
8592 /* arg1 code' CST' might be more canonical. */
8594 }
8595 else
8596 {
8597 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8601 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8605 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8609 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8613 else
8616 }
8618 /* Now build the constant reduced in magnitude. But not if that
8619 would produce one outside of its types range. */
8627 /* We cannot swap the comparison here as that would cause us to
8628 endlessly recurse. */
8637 /* If swapping might yield to a more canonical form, do so. */
8640 else
8642 }
8644 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8645 overflow further. Try to decrease the magnitude of constants involved
8646 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8647 and put sole constants at the second argument position.
8648 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8650 static tree
8653 {
8654 tree t;
8659 /* Try canonicalization by simplifying arg0. */
8664 {
8668 }
8670 /* Try canonicalization by simplifying arg1 using the swapped
8671 comparison. */
8679 }
8681 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8682 space. This is used to avoid issuing overflow warnings for
8683 expressions like &p->x which can not wrap. */
8685 static bool
8687 {
8694 wide_int wi_offset;
8700 else
8716 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8717 array. */
8719 {
8720 HOST_WIDE_INT base_size;
8725 }
8728 }
8730 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8731 kind INTEGER_CST. This makes sure to properly sign-extend the
8732 constant. */
8734 static HOST_WIDE_INT
8736 {
8742 }
8744 /* Subroutine of fold_binary. This routine performs all of the
8745 transformations that are common to the equality/inequality
8746 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8747 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8748 fold_binary should call fold_binary. Fold a comparison with
8749 tree code CODE and type TYPE with operands OP0 and OP1. Return
8750 the folded comparison or NULL_TREE. */
8752 static tree
8755 {
8765 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8767 && (equality_code
8774 {
8775 const enum tree_code
8782 /* If the constant operation overflowed this can be
8783 simplified as a comparison against INT_MAX/INT_MIN. */
8786 {
8790 /* Get the sign of the constant on the lhs if the
8791 operation were VARIABLE + CONST1. */
8795 /* The sign of the constant determines if we overflowed
8796 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8797 Canonicalize to the INT_MIN overflow by swapping the comparison
8798 if necessary. */
8802 /* We now can look at the canonicalized case
8803 VARIABLE + 1 CODE2 INT_MIN
8804 and decide on the result. */
8806 {
8810 return
8816 return
8821 }
8822 }
8823 else
8824 {
8827 "when changing X +- C1 cmp C2 to "
8829 WARN_STRICT_OVERFLOW_COMPARISON);
8831 }
8832 }
8834 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8836 && equality_code
8838 {
8839 /* ??? The transformation is valid for the other operators if overflow
8840 is undefined for the type, but performing it here badly interacts
8841 with the transformation in fold_cond_expr_with_comparison which
8842 attempts to synthetize ABS_EXPR. */
8846 WARN_STRICT_OVERFLOW_COMPARISON);
8849 }
8851 /* For comparisons of pointers we can decompose it to a compile time
8852 comparison of the base objects and the offsets into the object.
8853 This requires at least one operand being an ADDR_EXPR or a
8854 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8860 {
8863 machine_mode mode;
8867 /* Get base and offset for the access. Strip ADDR_EXPR for
8868 get_inner_reference, but put it back by stripping INDIRECT_REF
8869 off the base object if possible. indirect_baseN will be true
8870 if baseN is not an address but refers to the object itself. */
8873 {
8879 else
8881 }
8883 {
8887 {
8890 }
8893 {
8898 {
8901 }
8902 }
8903 }
8907 {
8913 else
8915 }
8917 {
8921 {
8924 }
8927 {
8932 {
8935 }
8936 }
8937 }
8939 /* A local variable can never be pointed to by
8940 the default SSA name of an incoming parameter. */
8942 && indirect_base0
8945 && !indirect_base1
8950 && indirect_base1
8953 && !indirect_base0
8957 {
8962 }
8963 /* If we have equivalent bases we might be able to simplify. */
8966 {
8967 /* We can fold this expression to a constant if the non-constant
8968 offset parts are equal. */
8977 {
8983 "occur when comparing P +- C1 with "
8985 WARN_STRICT_OVERFLOW_CONDITIONAL);
8988 {
9002 }
9003 }
9004 /* We can simplify the comparison to a comparison of the variable
9005 offset parts if the constant offset parts are equal.
9006 Be careful to use signed sizetype here because otherwise we
9007 mess with array offsets in the wrong way. This is possible
9008 because pointer arithmetic is restricted to retain within an
9009 object and overflow on pointer differences is undefined as of
9010 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9012 && (equality_code
9015 {
9016 /* By converting to signed sizetype we cover middle-end pointer
9017 arithmetic which operates on unsigned pointer types of size
9018 type size and ARRAY_REF offsets which are properly sign or
9019 zero extended from their type in case it is narrower than
9020 sizetype. */
9023 else
9027 else
9034 "occur when comparing P +- C1 with "
9036 WARN_STRICT_OVERFLOW_COMPARISON);
9039 }
9040 }
9041 /* For non-equal bases we can simplify if they are addresses
9042 declarations with different addresses. */
9044 /* We know that !operand_equal_p (base0, base1, 0)
9045 because the if condition was false. But make
9046 sure two decls are not the same. */
9052 /* Watch for aliases. */
9057 {
9064 }
9065 /* For equal offsets we can simplify to a comparison of the
9066 base addresses. */
9068 && (indirect_base0
9070 && (indirect_base1
9075 {
9081 }
9082 }
9084 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9085 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9086 the resulting offset is smaller in absolute value than the
9087 original one and has the same sign. */
9096 {
9101 tree cst;
9103 "occur when combining constants around "
9106 /* Put the constant on the side where it doesn't overflow and is
9107 of lower absolute value and of same sign than before. */
9114 {
9117 variable1,
9121 }
9129 {
9135 variable2);
9136 }
9137 }
9139 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9140 signed arithmetic case. That form is created by the compiler
9141 often enough for folding it to be of value. One example is in
9142 computing loop trip counts after Operator Strength Reduction. */
9149 {
9155 /* Handle unfolded multiplication by zero. */
9160 "eliminating multiplication in comparison "
9162 WARN_STRICT_OVERFLOW_COMPARISON);
9164 /* If const1 is negative we swap the sense of the comparison. */
9169 }
9176 {
9184 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9190 /* (-a) CMP (-b) -> b CMP a */
9197 {
9198 REAL_VALUE_TYPE cst;
9201 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9208 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9209 /* a CMP (-0) -> a CMP 0 */
9214 /* x != NaN is always true, other ops are always false. */
9217 {
9220 }
9222 /* Fold comparisons against infinity. */
9225 {
9229 }
9230 }
9232 /* If this is a comparison of a real constant with a PLUS_EXPR
9233 or a MINUS_EXPR of a real constant, we can convert it into a
9234 comparison with a revised real constant as long as no overflow
9235 occurs when unsafe_math_optimizations are enabled. */
9247 /* Likewise, we can simplify a comparison of a real constant with
9248 a MINUS_EXPR whose first operand is also a real constant, i.e.
9249 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9250 floating-point types only if -fassociative-math is set. */
9256 arg1))
9261 /* Fold comparisons against built-in math functions. */
9263 && flag_unsafe_math_optimizations
9265 {
9269 {
9273 }
9274 }
9275 }
9279 {
9280 /* If we are widening one operand of an integer comparison,
9281 see if the other operand is similarly being widened. Perhaps we
9282 can do the comparison in the narrower type. */
9287 /* Or if we are changing signedness. */
9291 }
9293 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9294 constant, we can simplify it. */
9299 {
9303 }
9305 /* Simplify comparison of something with itself. (For IEEE
9306 floating-point, we can only do some of these simplifications.) */
9308 {
9310 {
9325 /* For NE, we can only do this simplification if integer
9326 or we don't honor IEEE floating point NaNs. */
9330 /* ... fall through ... */
9336 }
9337 }
9339 /* If we are comparing an expression that just has comparisons
9340 of two integer values, arithmetic expressions of those comparisons,
9341 and constants, we can simplify it. There are only three cases
9342 to check: the two values can either be equal, the first can be
9343 greater, or the second can be greater. Fold the expression for
9344 those three values. Since each value must be 0 or 1, we have
9345 eight possibilities, each of which corresponds to the constant 0
9346 or 1 or one of the six possible comparisons.
9348 This handles common cases like (a > b) == 0 but also handles
9349 expressions like ((x > y) - (y > x)) > 0, which supposedly
9350 occur in macroized code. */
9353 {
9358 /* Don't handle degenerate cases here; they should already
9359 have been handled anyway. */
9368 {
9372 /* We can't just pass T to eval_subst in case cval1 or cval2
9373 was the same as ARG1. */
9375 tree high_result
9379 arg1);
9380 tree equal_result
9384 arg1);
9385 tree low_result
9389 arg1);
9391 /* All three of these results should be 0 or 1. Confirm they are.
9392 Then use those values to select the proper code to use. */
9397 {
9398 /* Make a 3-bit mask with the high-order bit being the
9399 value for `>', the next for '=', and the low for '<'. */
9403 {
9405 /* Always false. */
9426 /* Always true. */
9428 }
9431 {
9435 }
9437 }
9438 }
9439 }
9441 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9442 into a single range test. */
9450 {
9454 }
9456 /* Fold ~X op ~Y as Y op X. */
9459 {
9465 }
9467 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9470 {
9476 }
9479 }
9482 /* Subroutine of fold_binary. Optimize complex multiplications of the
9483 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9484 argument EXPR represents the expression "z" of type TYPE. */
9486 static tree
9488 {
9493 {
9496 }
9498 {
9501 }
9502 else
9503 {
9507 }
9516 }
9519 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9520 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9521 guarantees that P and N have the same least significant log2(M) bits.
9522 N is not otherwise constrained. In particular, N is not normalized to
9523 0 <= N < M as is common. In general, the precise value of P is unknown.
9524 M is chosen as large as possible such that constant N can be determined.
9526 Returns M and sets *RESIDUE to N.
9528 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9529 account. This is not always possible due to PR 35705.
9530 */
9532 static unsigned HOST_WIDE_INT
9535 {
9542 {
9547 }
9549 {
9557 allow_func_align);
9563 {
9566 }
9568 {
9571 {
9574 /* Compute the greatest power-of-2 divisor of op1. */
9578 /* If align is non-zero and less than *modulus, replace
9579 *modulus with align., If align is 0, then either op1 is 0
9580 or the greatest power-of-2 divisor of op1 doesn't fit in an
9581 unsigned HOST_WIDE_INT. In either case, no additional
9582 constraint is imposed. */
9587 }
9588 }
9589 }
9591 /* If we get here, we were unable to determine anything useful about the
9592 expression. */
9594 }
9596 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9597 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9599 static bool
9601 {
9605 {
9608 }
9610 {
9616 else
9618 }
9619 else
9625 }
9627 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9628 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9629 NULL_TREE otherwise. */
9631 static tree
9633 {
9650 {
9654 }
9657 {
9663 }
9664 else
9666 }
9668 /* Try to fold a pointer difference of type TYPE two address expressions of
9669 array references AREF0 and AREF1 using location LOC. Return a
9670 simplified expression for the difference or NULL_TREE. */
9672 static tree
9675 {
9680 /* If the bases are array references as well, recurse. If the bases
9681 are pointer indirections compute the difference of the pointers.
9682 If the bases are equal, we are set. */
9685 && (base_offset
9693 {
9699 base_offset,
9702 }
9704 }
9706 /* If the real or vector real constant CST of type TYPE has an exact
9707 inverse, return it, else return NULL. */
9709 tree
9711 {
9712 REAL_VALUE_TYPE r;
9714 machine_mode mode;
9718 {
9734 {
9739 }
9745 }
9746 }
9748 /* Mask out the tz least significant bits of X of type TYPE where
9749 tz is the number of trailing zeroes in Y. */
9750 static wide_int
9752 {
9757 }
9759 /* Return true when T is an address and is known to be nonzero.
9760 For floating point we further ensure that T is not denormal.
9761 Similar logic is present in nonzero_address in rtlanal.h.
9763 If the return value is based on the assumption that signed overflow
9764 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9765 change *STRICT_OVERFLOW_P. */
9767 static bool
9769 {
9773 /* Doing something useful for floating point would need more work. */
9779 {
9782 strict_overflow_p);
9788 strict_overflow_p);
9796 }
9799 {
9802 strict_overflow_p);
9810 strict_overflow_p);
9825 strict_overflow_p);
9829 strict_overflow_p);
9832 {
9844 }
9848 }
9850 }
9852 /* Return true when T is an address and is known to be nonzero.
9853 Handle warnings about undefined signed overflow. */
9855 static bool
9857 {
9864 "determining that expression is always "
9866 WARN_STRICT_OVERFLOW_MISC);
9868 }
9870 /* Fold a binary expression of code CODE and type TYPE with operands
9871 OP0 and OP1. LOC is the location of the resulting expression.
9872 Return the folded expression if folding is successful. Otherwise,
9873 return NULL_TREE. */
9875 tree
9878 {
9893 /* Strip any conversions that don't change the mode. This is
9894 safe for every expression, except for a comparison expression
9895 because its signedness is derived from its operands. So, in
9896 the latter case, only strip conversions that don't change the
9897 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9898 preserved.
9900 Note that this is done as an internal manipulation within the
9901 constant folder, in order to find the simplest representation
9902 of the arguments so that their form can be studied. In any
9903 cases, the appropriate type conversions should be put back in
9904 the tree that will get out of the constant folder. */
9907 {
9910 }
9911 else
9912 {
9915 }
9917 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9918 constant but we can't do arithmetic on them. */
9920 {
9923 {
9927 }
9928 }
9930 /* If this is a commutative operation, and ARG0 is a constant, move it
9931 to ARG1 to reduce the number of tests below. */
9936 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9937 to ARG1 to reduce the number of tests below. */
9946 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9948 First check for cases where an arithmetic operation is applied to a
9949 compound, conditional, or comparison operation. Push the arithmetic
9950 operation inside the compound or conditional to see if any folding
9951 can then be done. Convert comparison to conditional for this purpose.
9952 The also optimizes non-constant cases that used to be done in
9953 expand_expr.
9955 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9956 one of the operands is a comparison and the other is a comparison, a
9957 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9958 code below would make the expression more complex. Change it to a
9959 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9960 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9973 {
9977 boolean_type_node,
9985 }
9989 {
9991 {
9996 tem);
9997 }
10000 {
10005 tem);
10006 }
10011 {
10017 }
10022 {
10028 }
10029 }
10032 {
10034 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10037 {
10043 }
10045 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10048 {
10049 tree base;
10050 HOST_WIDE_INT coffset;
10059 }
10064 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10070 arg1),
10072 arg0)));
10078 {
10079 /* X + (X / CST) * -CST is X % CST. */
10084 {
10093 cst0));
10094 }
10095 }
10097 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10098 one. Make sure the type is not saturating and has the signedness of
10099 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10100 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10107 {
10111 }
10114 {
10115 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10116 with a constant, and the two constants have no bits in common,
10117 we should treat this as a BIT_IOR_EXPR since this may produce more
10118 simplifications. */
10125 {
10128 }
10130 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10131 (plus (plus (mult) (mult)) (foo)) so that we can
10132 take advantage of the factoring cases below. */
10141 {
10147 else
10160 parg0),
10162 marg)),
10166 return
10172 parg1)));
10173 }
10174 }
10175 else
10176 {
10177 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10178 to __complex__ ( x, y ). This is not the same for SNaNs or
10179 if signed zeros are involved. */
10183 {
10190 {
10194 {
10200 }
10202 {
10208 }
10209 }
10210 }
10218 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10219 We associate floats only if the user has specified
10220 -fassociative-math. */
10224 {
10229 {
10230 tree tree0;
10233 }
10234 }
10235 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10236 We associate floats only if the user has specified
10237 -fassociative-math. */
10241 {
10246 {
10247 tree tree0;
10250 }
10251 }
10252 }
10254 bit_rotate:
10255 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10256 is a rotate of A by C1 bits. */
10257 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10258 is a rotate of A by B bits. */
10259 {
10261 tree rtype;
10270 /* Only create rotates in complete modes. Other cases are not
10271 expanded properly. */
10274 {
10288 {
10292 code0 == LSHIFT_EXPR
10296 }
10298 {
10306 element_precision
10310 return
10313 ? LROTATE_EXPR
10318 }
10320 {
10328 element_precision
10332 return fold_convert_loc
10335 ? LROTATE_EXPR
10339 }
10340 }
10341 }
10343 associate:
10344 /* In most languages, can't associate operations on floats through
10345 parentheses. Rather than remember where the parentheses were, we
10346 don't associate floats at all, unless the user has specified
10347 -fassociative-math.
10348 And, we need to make sure type is not saturating. */
10352 {
10358 /* Split both trees into variables, constants, and literals. Then
10359 associate each group together, the constants with literals,
10360 then the result with variables. This increases the chances of
10361 literals being recombined later and of generating relocatable
10362 expressions for the sum of a constant and literal. */
10367 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10371 /* With undefined overflow prefer doing association in a type
10372 which wraps on overflow, if that is one of the operand types. */
10375 {
10383 }
10385 /* With undefined overflow we can only associate constants with one
10386 variable, and constants whose association doesn't overflow. */
10389 {
10391 {
10409 /* The only case we can still associate with two variables
10410 is if they are the same, modulo negation and bit-pattern
10411 preserving conversions. */
10414 }
10415 }
10417 /* Only do something if we found more than two objects. Otherwise,
10418 nothing has changed and we risk infinite recursion. */
10424 {
10436 /* Preserve the MINUS_EXPR if the negative part of the literal is
10437 greater than the positive part. Otherwise, the multiplicative
10438 folding code (i.e extract_muldiv) may be fooled in case
10439 unsigned constants are subtracted, like in the following
10440 example: ((X*2 + 4) - 8U)/2. */
10442 {
10446 {
10450 }
10451 else
10452 {
10456 }
10457 }
10459 /* Don't introduce overflows through reassociation. */
10466 {
10468 return
10472 else
10473 {
10476 return
10480 }
10481 }
10484 return
10487 }
10488 }
10493 /* Pointer simplifications for subtraction, simple reassociations. */
10495 {
10496 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10499 {
10509 }
10510 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10512 {
10519 }
10520 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10521 simplifies. */
10523 {
10530 arg10);
10533 }
10534 }
10535 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10545 /* X - (X / Y) * Y is X % Y. */
10553 return
10559 {
10560 /* Fold A - (A & B) into ~B & A. */
10563 {
10565 {
10572 }
10574 {
10581 }
10582 }
10584 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10585 any power of 2 minus 1. */
10590 {
10596 {
10600 }
10601 }
10602 }
10604 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10605 __complex__ ( x, -y ). This is not the same for SNaNs or if
10606 signed zeros are involved. */
10610 {
10617 {
10621 {
10623 arg1r ? arg1r
10628 }
10630 {
10634 arg1i ? arg1i
10637 }
10638 }
10639 }
10641 /* A - B -> A + (-B) if B is easily negatable. */
10645 /* Avoid this transformation if B is a positive REAL_CST. */
10654 /* Try folding difference of addresses. */
10655 {
10656 HOST_WIDE_INT diff;
10662 }
10664 /* Fold &a[i] - &a[j] to i-j. */
10669 {
10675 }
10678 && flag_unsafe_math_optimizations
10684 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10685 one. Make sure the type is not saturating and has the signedness of
10686 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10687 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10694 {
10698 }
10703 /* (-A) * (-B) -> A * B */
10718 {
10719 /* Transform x * -C into -x * C if x is easily negatable. */
10728 tem);
10730 /* (a * (1 << b)) is (a << b) */
10740 /* (A + A) * C -> A * 2 * C */
10752 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10753 sign-changing only. */
10763 {
10766 "occur when simplifying "
10768 WARN_STRICT_OVERFLOW_MISC);
10770 }
10772 /* Optimize z * conj(z) for integer complex numbers. */
10779 }
10780 else
10781 {
10782 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10783 the result for floating point types due to rounding so it is applied
10784 only if -fassociative-math was specify. */
10789 {
10791 arg1);
10795 }
10797 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10799 {
10802 {
10805 }
10806 }
10808 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10809 This is not the same for NaNs or if signed zeros are
10810 involved. */
10816 {
10819 return
10825 return
10830 }
10832 /* Optimize z * conj(z) for floating point complex numbers.
10833 Guarded by flag_unsafe_math_optimizations as non-finite
10834 imaginary components don't produce scalar results. */
10845 {
10849 /* Optimizations of root(...)*root(...). */
10851 {
10856 /* Optimize sqrt(x)*sqrt(x) as x. */
10862 /* Optimize root(x)*root(y) as root(x*y). */
10866 }
10868 /* Optimize expN(x)*expN(y) as expN(x+y). */
10870 {
10876 }
10878 /* Optimizations of pow(...)*pow(...). */
10882 {
10888 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10890 {
10895 }
10897 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10899 {
10904 }
10905 }
10907 /* Optimize tan(x)*cos(x) as sin(x). */
10916 {
10922 }
10924 /* Optimize x*pow(x,c) as pow(x,c+1). */
10928 {
10934 {
10936 REAL_VALUE_TYPE c;
10937 tree arg;
10943 }
10944 }
10946 /* Optimize pow(x,c)*x as pow(x,c+1). */
10950 {
10956 {
10958 REAL_VALUE_TYPE c;
10959 tree arg;
10965 }
10966 }
10968 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10970 && optimize
10972 {
10976 {
10979 }
10980 }
10981 }
10982 }
10986 bit_ior:
10987 /* ~X | X is -1. */
10990 {
10994 }
10996 /* X | ~X is -1. */
10999 {
11003 }
11005 /* Canonicalize (X & C1) | C2. */
11009 {
11014 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11022 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11027 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11028 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11029 mode which allows further optimizations. */
11034 {
11038 {
11041 }
11042 }
11049 c3)),
11050 arg1);
11051 }
11053 /* (X & ~Y) | (~X & Y) is X ^ Y */
11056 {
11073 }
11079 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11081 This results in more efficient code for machines without a NAND
11082 instruction. Combine will canonicalize to the first form
11083 which will allow use of NAND instructions provided by the
11084 backend if they exist. */
11087 {
11088 return
11095 }
11097 /* See if this can be simplified into a rotate first. If that
11098 is unsuccessful continue in the association code. */
11102 /* ~X ^ X is -1. */
11105 {
11109 }
11111 /* X ^ ~X is -1. */
11114 {
11118 }
11120 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11121 with a constant, and the two constants have no bits in common,
11122 we should treat this as a BIT_IOR_EXPR since this may produce more
11123 simplifications. */
11130 {
11133 }
11135 /* (X | Y) ^ X -> Y & ~ X*/
11138 {
11141 arg1);
11146 }
11148 /* (Y | X) ^ X -> Y & ~ X*/
11151 {
11154 arg1);
11159 }
11161 /* X ^ (X | Y) -> Y & ~ X*/
11164 {
11167 arg0);
11172 }
11174 /* X ^ (Y | X) -> Y & ~ X*/
11177 {
11180 arg0);
11185 }
11187 /* Convert ~X ^ ~Y to X ^ Y. */
11196 /* Convert ~X ^ C to X ^ ~C. */
11204 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11212 /* Fold (X & Y) ^ Y as ~X & Y. */
11215 {
11220 }
11221 /* Fold (X & Y) ^ X as ~Y & X. */
11225 {
11230 }
11231 /* Fold X ^ (X & Y) as X & ~Y. */
11234 {
11239 }
11240 /* Fold X ^ (Y & X) as ~Y & X. */
11244 {
11249 }
11251 /* See if this can be simplified into a rotate first. If that
11252 is unsuccessful continue in the association code. */
11256 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11264 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11272 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11277 {
11278 tree tem2;
11285 }
11286 /* Fold ~X & 1 as (X & 1) == 0. */
11290 {
11291 tree tem2;
11298 }
11299 /* Fold !X & 1 as X == 0. */
11302 {
11306 }
11308 /* Fold (X ^ Y) & Y as ~X & Y. */
11311 {
11316 }
11317 /* Fold (X ^ Y) & X as ~Y & X. */
11321 {
11326 }
11327 /* Fold X & (X ^ Y) as X & ~Y. */
11330 {
11335 }
11336 /* Fold X & (Y ^ X) as ~Y & X. */
11340 {
11345 }
11347 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11348 multiple of 1 << CST. */
11350 {
11357 }
11359 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11360 bits from CST2. */
11364 {
11372 {
11373 /* Avoid the transform if arg1 is a mask of some
11374 mode which allows further optimizations. */
11381 }
11382 }
11384 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11385 ((A & N) + B) & M -> (A + B) & M
11386 Similarly if (N & M) == 0,
11387 ((A | N) + B) & M -> (A + B) & M
11388 and for - instead of + (or unary - instead of +)
11389 and/or ^ instead of |.
11390 If B is constant and (B & M) == 0, fold into A & M. */
11392 {
11401 {
11404 wide_int cst0;
11406 /* Now we know that arg0 is (C + D) or (C - D) or
11407 -C and arg1 (M) is == (1LL << cst) - 1.
11408 Store C into PMOP[0] and D into PMOP[1]. */
11412 {
11415 }
11422 {
11432 {
11435 }
11438 /* If C or D is of the form (A & N) where
11439 (N & M) == M, or of the form (A | N) or
11440 (A ^ N) where (N & M) == 0, replace it with A. */
11444 /* If C or D is a N where (N & M) == 0, it can be
11445 omitted (assumed 0). */
11453 }
11455 /* Only build anything new if we optimized one or both arguments
11456 above. */
11460 {
11463 {
11464 /* Perform the operations in a type that has defined
11465 overflow behavior. */
11471 }
11476 {
11484 else
11486 }
11489 else
11492 /* TEM is now the new binary +, - or unary - replacement. */
11496 }
11497 }
11498 }
11503 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11506 {
11511 return
11513 }
11515 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11517 This results in more efficient code for machines without a NOR
11518 instruction. Combine will canonicalize to the first form
11519 which will allow use of NOR instructions provided by the
11520 backend if they exist. */
11523 {
11530 }
11532 /* If arg0 is derived from the address of an object or function, we may
11533 be able to fold this expression using the object or function's
11534 alignment. */
11536 {
11543 /* This works because modulus is a power of 2. If this weren't the
11544 case, we'd have to replace it by its greatest power-of-2
11545 divisor: modulus & -modulus. */
11548 }
11550 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11551 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11552 if the new mask might be further optimized. */
11561 {
11572 {
11575 /* See if more bits can be proven as zero because of
11576 zero extension. */
11579 {
11584 {
11586 /* See if we can shorten the right shift. */
11589 /* Otherwise X >> C1 is all zeros, so we'll optimize
11590 it into (X, 0) later on by making sure zerobits
11591 is all ones. */
11592 }
11593 }
11596 {
11599 }
11600 /* For arithmetic shift if sign bit could be set, zerobits
11601 can contain actually sign bits, so no transformation is
11602 possible, unless MASK masks them all away. In that
11603 case the shift needs to be converted into logical shift. */
11606 {
11609 else
11611 }
11612 }
11614 /* ((X << 16) & 0xff00) is (X, 0). */
11621 {
11622 /* Only do the transformation if NEWMASK is some integer
11623 mode's mask. */
11630 {
11631 tree newmaskt;
11634 {
11640 }
11641 else
11646 }
11647 }
11648 }
11653 /* Don't touch a floating-point divide by zero unless the mode
11654 of the constant can represent infinity. */
11660 /* (-A) / (-B) -> A / B */
11670 /* Convert A/B/C to A/(B*C). */
11677 /* Convert A/(B/C) to (A/B)*C. */
11685 /* Convert C1/(X*C2) into (C1/C2)/X. */
11690 {
11696 }
11699 {
11703 /* Optimize sin(x)/cos(x) as tan(x). */
11709 {
11714 }
11716 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11722 {
11726 {
11731 }
11732 }
11734 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11735 NaNs or Infinities. */
11739 {
11746 {
11751 }
11752 }
11754 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11755 NaNs or Infinities. */
11759 {
11766 {
11770 {
11774 tmp);
11775 }
11776 }
11777 }
11779 /* Optimize pow(x,c)/x as pow(x,c-1). */
11783 {
11789 {
11791 REAL_VALUE_TYPE c;
11792 tree arg;
11798 }
11799 }
11801 /* Optimize a/root(b/c) into a*root(c/b). */
11803 {
11807 {
11816 }
11817 }
11819 /* Optimize x/expN(y) into x*expN(-y). */
11821 {
11828 }
11830 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11834 {
11842 }
11843 }
11847 /* Optimize (X & (-A)) / A where A is a power of 2,
11848 to X >> log2(A) */
11852 {
11860 }
11861 }
11863 /* Fall through */
11866 /* Simplify A / (B << N) where A and B are positive and B is
11867 a power of 2, to A >> (N + log2(B)). */
11872 {
11875 {
11883 WARN_STRICT_OVERFLOW_MISC);
11889 }
11890 }
11892 /* Fall through */
11900 /* Convert -A / -B to A / B when the type is signed and overflow is
11901 undefined. */
11905 {
11908 "when distributing negation across "
11910 WARN_STRICT_OVERFLOW_MISC);
11916 }
11920 {
11923 "when distributing negation across "
11925 WARN_STRICT_OVERFLOW_MISC);
11931 }
11933 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11934 operation, EXACT_DIV_EXPR.
11936 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11937 At one time others generated faster code, it's not clear if they do
11938 after the last round to changes to the DIV code in expmed.c. */
11947 {
11951 WARN_STRICT_OVERFLOW_MISC);
11953 }
11961 /* X % -Y is the same as X % Y. */
11974 {
11978 WARN_STRICT_OVERFLOW_MISC);
11980 }
11982 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11983 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11987 {
11989 /* Also optimize A % (C << N) where C is a power of 2,
11990 to A & ((C << N) - 1). */
11995 {
11996 tree mask
12001 "occur when simplifying "
12003 WARN_STRICT_OVERFLOW_MISC);
12007 }
12008 }
12016 /* Since negative shift count is not well-defined,
12017 don't try to compute it in the compiler. */
12023 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12028 {
12032 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12033 being well defined. */
12035 {
12041 else
12043 }
12047 }
12049 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12050 into x & ((unsigned)-1 >> c) for unsigned types. */
12058 {
12061 tree lshift;
12062 tree arg00;
12065 {
12072 }
12073 }
12075 /* If we have a rotate of a bit operation with the rotate count and
12076 the second operand of the bit operation both constant,
12077 permute the two operations. */
12089 /* Two consecutive rotates adding up to the some integer
12090 multiple of the precision of the type can be ignored. */
12098 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12099 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12100 if the latter can be further optimized. */
12105 {
12109 arg1);
12113 arg1);
12117 }
12134 /* Note that the operands of this must be ints
12135 and their values must be 0 or 1.
12136 ("true" is a fixed value perhaps depending on the language.) */
12137 /* If first arg is constant zero, return it. */
12141 /* If either arg is constant true, drop it. */
12145 /* Preserve sequence points. */
12148 /* If second arg is constant zero, result is zero, but first arg
12149 must be evaluated. */
12152 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12153 case will be handled here. */
12157 /* !X && X is always false. */
12161 /* X && !X is always false. */
12166 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12167 means A >= Y && A != MAX, but in this case we know that
12168 A < X <= MAX. */
12172 {
12180 }
12189 /* Note that the operands of this must be ints
12190 and their values must be 0 or true.
12191 ("true" is a fixed value perhaps depending on the language.) */
12192 /* If first arg is constant true, return it. */
12196 /* If either arg is constant zero, drop it. */
12200 /* Preserve sequence points. */
12203 /* If second arg is constant true, result is true, but we must
12204 evaluate first arg. */
12207 /* Likewise for first arg, but note this only occurs here for
12208 TRUTH_OR_EXPR. */
12212 /* !X || X is always true. */
12216 /* X || !X is always true. */
12221 /* (X && !Y) || (!X && Y) is X ^ Y */
12224 {
12241 }
12250 /* If the second arg is constant zero, drop it. */
12253 /* If the second arg is constant true, this is a logical inversion. */
12255 {
12258 }
12259 /* Identical arguments cancel to zero. */
12263 /* !X ^ X is always true. */
12268 /* X ^ !X is always true. */
12284 /* bool_var != 0 becomes bool_var. */
12289 /* bool_var == 1 becomes bool_var. */
12294 /* bool_var != 1 becomes !bool_var. */
12301 /* bool_var == 0 becomes !bool_var. */
12308 /* !exp != 0 becomes !exp */
12313 /* If this is an equality comparison of the address of two non-weak,
12314 unaliased symbols neither of which are extern (since we do not
12315 have access to attributes for externs), then we know the result. */
12320 {
12328 else
12333 type);
12334 }
12336 /* Similarly for a NEGATE_EXPR. */
12340 arg1)))
12345 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12353 arg1),
12356 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12365 {
12369 val,
12373 }
12375 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12382 {
12384 code == NE_EXPR
12387 }
12389 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12394 /* If this is an EQ or NE comparison with zero and ARG0 is
12395 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12396 two operations, but the latter can be done in one less insn
12397 on machines that have only two-operand insns or on which a
12398 constant cannot be the first operand. */
12401 {
12406 {
12413 arg1);
12414 }
12417 {
12424 arg1);
12425 }
12426 }
12428 /* If this is an NE or EQ comparison of zero against the result of a
12429 signed MOD operation whose second operand is a power of 2, make
12430 the MOD operation unsigned since it is simpler and equivalent. */
12438 {
12448 }
12450 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12451 C1 is a valid shift constant, and C2 is a power of two, i.e.
12452 a single bit. */
12456 == INTEGER_CST
12459 {
12464 /* Check for a valid shift count. */
12466 {
12470 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12471 can be rewritten as (X & (C2 << C1)) != 0. */
12473 {
12478 }
12479 /* Otherwise, for signed (arithmetic) shifts,
12480 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12481 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12485 /* Otherwise, of unsigned (logical) shifts,
12486 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12487 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12488 else
12492 arg000);
12493 }
12494 }
12496 /* If we have (A & C) == C where C is a power of 2, convert this into
12497 (A & C) != 0. Similarly for NE_EXPR. */
12503 integer_zero_node));
12505 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12506 bit, then fold the expression into A < 0 or A >= 0. */
12511 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12512 Similarly for NE_EXPR. */
12516 {
12520 tree dandnotc
12523 notc);
12527 }
12529 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12530 Similarly for NE_EXPR. */
12534 {
12536 tree candnotd
12543 }
12545 /* If this is a comparison of a field, we may be able to simplify it. */
12548 /* Handle the constant case even without -O
12549 to make sure the warnings are given. */
12551 {
12555 }
12557 /* Optimize comparisons of strlen vs zero to a compare of the
12558 first character of the string vs zero. To wit,
12559 strlen(ptr) == 0 => *ptr == 0
12560 strlen(ptr) != 0 => *ptr != 0
12561 Other cases should reduce to one of these two (or a constant)
12562 due to the return value of strlen being unsigned. */
12565 {
12573 {
12578 }
12579 }
12581 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12582 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12586 {
12591 {
12593 {
12596 }
12599 }
12600 }
12602 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12608 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12613 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12620 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12628 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12629 (X & C) == 0 when C is a single bit. */
12634 {
12641 arg1));
12642 }
12644 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12645 constant C is a power of two, i.e. a single bit. */
12652 {
12656 }
12658 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12659 when is C is a power of two, i.e. a single bit. */
12666 {
12672 }
12676 {
12679 }
12681 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12689 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12692 {
12705 arg01),
12714 arg01),
12723 arg00),
12732 arg00),
12734 }
12738 {
12745 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12746 operand_equal_p guarantees no side-effects so we don't need
12747 to use omit_one_operand on Z. */
12751 arg10));
12755 arg11));
12759 arg10));
12763 arg11));
12765 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12768 {
12774 }
12775 }
12777 /* Attempt to simplify equality/inequality comparisons of complex
12778 values. Only lower the comparison if the result is known or
12779 can be simplified to a single scalar comparison. */
12784 {
12789 {
12792 }
12793 else
12794 {
12797 }
12800 {
12803 }
12804 else
12805 {
12808 }
12812 {
12814 {
12819 }
12820 else
12821 {
12826 }
12827 }
12831 {
12833 {
12838 }
12839 else
12840 {
12845 }
12846 }
12847 }
12859 /* Transform comparisons of the form X +- C CMP X. */
12866 {
12873 else
12876 /* (X - c) > X becomes false. */
12880 {
12884 "occur when assuming that (X - c) > X "
12886 WARN_STRICT_OVERFLOW_ALL);
12888 }
12890 /* Likewise (X + c) < X becomes false. */
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 }
12919 /* Convert (X + c) >= X to true. */
12924 {
12928 "occur when assuming that "
12930 WARN_STRICT_OVERFLOW_ALL);
12932 }
12935 {
12936 /* Convert X + c > X and X - c < X to true for integers. */
12940 {
12943 "not occur when assuming that "
12945 WARN_STRICT_OVERFLOW_ALL);
12947 }
12952 {
12955 "not occur when assuming that "
12957 WARN_STRICT_OVERFLOW_ALL);
12959 }
12961 /* Convert X + c <= X and X - c >= X to false for integers. */
12965 {
12968 "not occur when assuming that "
12970 WARN_STRICT_OVERFLOW_ALL);
12972 }
12977 {
12980 "not occur when assuming that "
12982 WARN_STRICT_OVERFLOW_ALL);
12984 }
12985 }
12986 }
12988 /* Comparisons with the highest or lowest possible integer of
12989 the specified precision will have known values. */
12990 {
12996 {
13003 {
13016 /* The GE_EXPR and LT_EXPR cases above are not normally
13017 reached because of previous transformations. */
13021 }
13024 {
13031 arg1);
13037 arg0),
13038 arg1);
13041 }
13044 {
13059 }
13062 {
13069 arg1);
13075 arg0),
13076 arg1);
13079 }
13083 /* We will flip the signedness of the comparison operator
13084 associated with the mode of arg1, so the sign bit is
13085 specified by this mode. Check that arg1 is the signed
13086 max associated with this sign bit. */
13088 /* signed_type does not work on pointer types. */
13090 {
13091 /* The following case also applies to X < signed_max+1
13092 and X >= signed_max+1 because previous transformations. */
13094 {
13100 }
13101 }
13102 }
13103 }
13105 /* If we are comparing an ABS_EXPR with a constant, we can
13106 convert all the cases into explicit comparisons, but they may
13107 well not be faster than doing the ABS and one comparison.
13108 But ABS (X) <= C is a range comparison, which becomes a subtraction
13109 and a comparison, and is probably faster. */
13123 /* Convert ABS_EXPR<x> >= 0 to true. */
13130 {
13133 "when simplifying comparison of "
13135 WARN_STRICT_OVERFLOW_CONDITIONAL);
13138 arg0);
13139 }
13141 /* Convert ABS_EXPR<x> < 0 to false. */
13146 {
13149 "when simplifying comparison of "
13151 WARN_STRICT_OVERFLOW_CONDITIONAL);
13154 arg0);
13155 }
13157 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13158 and similarly for >= into !=. */
13168 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13169 otherwise Y might be >= # of bits in X's type and thus e.g.
13170 (unsigned char) (1 << Y) for Y 15 might be 0.
13171 If the cast is widening, then 1 << Y should have unsigned type,
13172 otherwise if Y is number of bits in the signed shift type minus 1,
13173 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13174 31 might be 0xffffffff80000000. */
13185 {
13191 }
13204 {
13208 }
13210 /* If the first operand is NaN, the result is constant. */
13214 {
13216 ? integer_zero_node
13219 }
13221 /* If the second operand is NaN, the result is constant. */
13225 {
13227 ? integer_zero_node
13230 }
13232 /* Simplify unordered comparison of something with itself. */
13238 && !flag_trapping_math
13242 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13243 {
13255 }
13260 /* When pedantic, a compound expression can be neither an lvalue
13261 nor an integer constant expression. */
13264 /* Don't let (0, 0) be null pointer constant. */
13270 /* An ASSERT_EXPR should never be passed to fold_binary. */
13276 }
13278 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13279 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13280 of GOTO_EXPR. */
13282 static tree
13284 {
13286 {
13293 /* ... fall through ... */
13297 }
13298 }
13300 /* Return whether the sub-tree ST contains a label which is accessible from
13301 outside the sub-tree. */
13303 static bool
13305 {
13306 return
13308 }
13310 /* Fold a ternary expression of code CODE and type TYPE with operands
13311 OP0, OP1, and OP2. Return the folded expression if folding is
13312 successful. Otherwise, return NULL_TREE. */
13314 tree
13317 {
13318 tree tem;
13325 /* If this is a commutative operation, and OP0 is a constant, move it
13326 to OP1 to reduce the number of tests below. */
13335 /* Strip any conversions that don't change the mode. This is safe
13336 for every expression, except for a comparison expression because
13337 its signedness is derived from its operands. So, in the latter
13338 case, only strip conversions that don't change the signedness.
13340 Note that this is done as an internal manipulation within the
13341 constant folder, in order to find the simplest representation of
13342 the arguments so that their form can be studied. In any cases,
13343 the appropriate type conversions should be put back in the tree
13344 that will get out of the constant folder. */
13346 {
13349 }
13352 {
13355 }
13358 {
13361 }
13364 {
13368 {
13374 }
13379 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13380 so all simple results must be passed through pedantic_non_lvalue. */
13382 {
13385 /* Only optimize constant conditions when the selected branch
13386 has the same type as the COND_EXPR. This avoids optimizing
13387 away "c ? x : throw", where the throw has a void type.
13388 Avoid throwing away that operand which contains label. */
13395 }
13397 {
13402 {
13407 {
13415 }
13419 }
13420 }
13422 /* If we have A op B ? A : C, we may be able to convert this to a
13423 simpler expression, depending on the operation and the values
13424 of B and C. Signed zeros prevent all of these transformations,
13425 for reasons given above each one.
13427 Also try swapping the arguments and inverting the conditional. */
13432 {
13436 }
13440 op2,
13443 {
13447 {
13451 }
13452 }
13454 /* If the second operand is simpler than the third, swap them
13455 since that produces better jump optimization results. */
13458 {
13460 /* See if this can be inverted. If it can't, possibly because
13461 it was a floating-point inequality comparison, don't do
13462 anything. */
13466 }
13468 /* Convert A ? 1 : 0 to simply A. */
13473 /* If we try to convert OP0 to our type, the
13474 call to fold will try to move the conversion inside
13475 a COND, which will recurse. In that case, the COND_EXPR
13476 is probably the best choice, so leave it alone. */
13480 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13481 over COND_EXPR in cases such as floating point comparisons. */
13490 arg0)));
13492 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13497 {
13498 /* sign_bit_p looks through both zero and sign extensions,
13499 but for this optimization only sign extensions are
13500 usable. */
13503 {
13506 {
13509 }
13511 }
13512 /* sign_bit_p only checks ARG1 bits within A's precision.
13513 If <sign bit of A> has wider type than A, bits outside
13514 of A's precision in <sign bit of A> need to be checked.
13515 If they are all 0, this optimization needs to be done
13516 in unsigned A's type, if they are all 1 in signed A's type,
13517 otherwise this can't be done. */
13523 {
13525 tree tem_type;
13538 {
13541 }
13543 {
13546 }
13547 else
13549 }
13552 return
13558 arg1)));
13559 }
13561 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13562 already handled above. */
13567 {
13576 }
13578 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13579 is probably obsolete because the first operand should be a
13580 truth value (that's why we have the two cases above), but let's
13581 leave it in until we can confirm this for all front-ends. */
13593 /* Disable the transformations below for vectors, since
13594 fold_binary_op_with_conditional_arg may undo them immediately,
13595 yielding an infinite loop. */
13599 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13608 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13613 {
13615 /* Only perform transformation if ARG0 is easily inverted. */
13619 ? BIT_IOR_EXPR
13622 arg1);
13623 }
13625 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13630 {
13632 /* Only perform transformation if ARG0 is easily inverted. */
13638 op2);
13639 }
13641 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13653 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13654 of fold_ternary on them. */
13664 {
13674 {
13679 {
13687 }
13689 /* Constructor elements can be subvectors. */
13692 {
13696 }
13698 /* We keep an exact subset of the constructor elements. */
13700 {
13706 {
13710 }
13718 CONSTRUCTOR_ELT
13721 }
13722 /* The bitfield references a single constructor element. */
13724 {
13729 else
13733 }
13734 }
13735 }
13737 /* A bit-field-ref that referenced the full argument can be stripped. */
13743 /* On constants we can use native encode/interpret to constant
13744 fold (nearly) all BIT_FIELD_REFs. */
13748 /* This limitation should not be necessary, we just need to
13749 round this up to mode size. */
13751 /* Need bit-shifting of the buffer to relax the following. */
13753 {
13758 /* ??? We cannot tell native_encode_expr to start at
13759 some random byte only. So limit us to a reasonable amount
13760 of work. */
13762 {
13767 {
13773 }
13774 }
13775 }
13780 /* For integers we can decompose the FMA if possible. */
13792 {
13808 {
13813 /* Make sure that the perm value is in an acceptable
13814 range. */
13823 else
13828 }
13831 {
13836 }
13841 {
13846 }
13852 {
13856 }
13861 /* Some targets are deficient and fail to expand a single
13862 argument permutation while still allowing an equivalent
13863 2-argument version. */
13867 {
13870 }
13873 {
13880 }
13884 }
13890 }
13892 /* Perform constant folding and related simplification of EXPR.
13893 The related simplifications include x*1 => x, x*0 => 0, etc.,
13894 and application of the associative law.
13895 NOP_EXPR conversions may be removed freely (as long as we
13896 are careful not to change the type of the overall expression).
13897 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13898 but we can constant-fold them if they have constant operands. */
13900 #ifdef ENABLE_FOLD_CHECKING
13901 # define fold(x) fold_1 (x)
13903 static
13904 #endif
13905 tree
13907 {
13911 tree tem;
13914 /* Return right away if a constant. */
13918 /* CALL_EXPR-like objects with variable numbers of operands are
13919 treated specially. */
13921 {
13923 {
13926 }
13928 }
13931 {
13936 {
13954 }
13955 }
13958 {
13960 {
13967 {
13972 /* Find a matching index by means of a binary search. */
13974 {
13990 else
13992 }
13993 }
13996 }
13998 /* Return a VECTOR_CST if possible. */
14000 {
14007 tree value;
14010 {
14014 {
14017 }
14018 else
14020 }
14025 }
14033 }
14035 #ifdef ENABLE_FOLD_CHECKING
14036 #undef fold
14043 /* When --enable-checking=fold, compute a digest of expr before
14044 and after actual fold call to see if fold did not accidentally
14045 change original expr. */
14047 tree
14049 {
14050 tree ret;
14070 }
14072 void
14074 {
14085 }
14087 static void
14089 {
14091 }
14093 static void
14096 {
14102 recursive_label:
14112 {
14113 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
14118 }
14125 {
14126 /* Allow these fields to be modified. */
14127 tree tmp;
14135 {
14138 }
14139 }
14150 {
14153 {
14168 }
14172 {
14185 }
14202 {
14208 }
14211 {
14213 {
14216 }
14218 }
14229 {
14232 }
14242 }
14243 }
14245 /* Helper function for outputting the checksum of a tree T. When
14246 debugging with gdb, you can "define mynext" to be "next" followed
14247 by "call debug_fold_checksum (op0)", then just trace down till the
14248 outputs differ. */
14250 DEBUG_FUNCTION void
14252 {
14267 }
14269 #endif
14271 /* Fold a unary tree expression with code CODE of type TYPE with an
14272 operand OP0. LOC is the location of the resulting expression.
14273 Return a folded expression if successful. Otherwise, return a tree
14274 expression with code CODE of type TYPE with an operand OP0. */
14276 tree
14279 {
14280 tree tem;
14281 #ifdef ENABLE_FOLD_CHECKING
14290 #endif
14296 #ifdef ENABLE_FOLD_CHECKING
14303 #endif
14305 }
14307 /* Fold a binary tree expression with code CODE of type TYPE with
14308 operands OP0 and OP1. LOC is the location of the resulting
14309 expression. Return a folded expression if successful. Otherwise,
14310 return a tree expression with code CODE of type TYPE with operands
14311 OP0 and OP1. */
14313 tree
14316 MEM_STAT_DECL)
14317 {
14318 tree tem;
14319 #ifdef ENABLE_FOLD_CHECKING
14336 #endif
14342 #ifdef ENABLE_FOLD_CHECKING
14357 #endif
14359 }
14361 /* Fold a ternary tree expression with code CODE of type TYPE with
14362 operands OP0, OP1, and OP2. Return a folded expression if
14363 successful. Otherwise, return a tree expression with code CODE of
14364 type TYPE with operands OP0, OP1, and OP2. */
14366 tree
14369 {
14370 tree tem;
14371 #ifdef ENABLE_FOLD_CHECKING
14395 #endif
14402 #ifdef ENABLE_FOLD_CHECKING
14425 #endif
14427 }
14429 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14430 arguments in ARGARRAY, and a null static chain.
14431 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14432 of type TYPE from the given operands as constructed by build_call_array. */
14434 tree
14437 {
14438 tree tem;
14439 #ifdef ENABLE_FOLD_CHECKING
14458 #endif
14464 #ifdef ENABLE_FOLD_CHECKING
14480 #endif
14482 }
14484 /* Perform constant folding and related simplification of initializer
14485 expression EXPR. These behave identically to "fold_buildN" but ignore
14486 potential run-time traps and exceptions that fold must preserve. */
14488 #define START_FOLD_INIT \
14489 int saved_signaling_nans = flag_signaling_nans;\
14490 int saved_trapping_math = flag_trapping_math;\
14491 int saved_rounding_math = flag_rounding_math;\
14492 int saved_trapv = flag_trapv;\
14493 int saved_folding_initializer = folding_initializer;\
14494 flag_signaling_nans = 0;\
14495 flag_trapping_math = 0;\
14496 flag_rounding_math = 0;\
14497 flag_trapv = 0;\
14498 folding_initializer = 1;
14500 #define END_FOLD_INIT \
14501 flag_signaling_nans = saved_signaling_nans;\
14502 flag_trapping_math = saved_trapping_math;\
14503 flag_rounding_math = saved_rounding_math;\
14504 flag_trapv = saved_trapv;\
14505 folding_initializer = saved_folding_initializer;
14507 tree
14510 {
14511 tree result;
14512 START_FOLD_INIT;
14516 END_FOLD_INIT;
14518 }
14520 tree
14523 {
14524 tree result;
14525 START_FOLD_INIT;
14529 END_FOLD_INIT;
14531 }
14533 tree
14536 {
14537 tree result;
14538 START_FOLD_INIT;
14542 END_FOLD_INIT;
14544 }
14546 #undef START_FOLD_INIT
14547 #undef END_FOLD_INIT
14549 /* Determine if first argument is a multiple of second argument. Return 0 if
14550 it is not, or we cannot easily determined it to be.
14552 An example of the sort of thing we care about (at this point; this routine
14553 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14554 fold cases do now) is discovering that
14556 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14558 is a multiple of
14560 SAVE_EXPR (J * 8)
14562 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14564 This code also handles discovering that
14566 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14568 is a multiple of 8 so we don't have to worry about dealing with a
14569 possible remainder.
14571 Note that we *look* inside a SAVE_EXPR only to determine how it was
14572 calculated; it is not safe for fold to do much of anything else with the
14573 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14574 at run time. For example, the latter example above *cannot* be implemented
14575 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14576 evaluation time of the original SAVE_EXPR is not necessarily the same at
14577 the time the new expression is evaluated. The only optimization of this
14578 sort that would be valid is changing
14580 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14582 divided by 8 to
14584 SAVE_EXPR (I) * SAVE_EXPR (J)
14586 (where the same SAVE_EXPR (J) is used in the original and the
14587 transformed version). */
14589 int
14591 {
14599 {
14601 /* Bitwise and provides a power of two multiple. If the mask is
14602 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14605 /* FALLTHRU */
14618 {
14622 /* const_binop may not detect overflow correctly,
14623 so check for it explicitly here. */
14627 size_one_node,
14628 op1)))
14631 }
14635 /* Can't handle conversions from non-integral or wider integral type. */
14641 /* .. fall through ... */
14658 SIGNED);
14662 }
14663 }
14665 /* Return true if CODE or TYPE is known to be non-negative. */
14667 static bool
14669 {
14672 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14673 have a signed:1 type (where the value is -1 and 0). */
14676 }
14678 /* Return true if (CODE OP0) is known to be non-negative. If the return
14679 value is based on the assumption that signed overflow is undefined,
14680 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14681 *STRICT_OVERFLOW_P. */
14683 bool
14686 {
14691 {
14693 /* We can't return 1 if flag_wrapv is set because
14694 ABS_EXPR<INT_MIN> = INT_MIN. */
14698 {
14701 }
14708 strict_overflow_p);
14710 CASE_CONVERT:
14711 {
14716 {
14719 strict_overflow_p);
14721 {
14725 strict_overflow_p);
14726 }
14727 }
14729 {
14732 strict_overflow_p);
14736 }
14737 }
14742 }
14744 /* We don't know sign of `t', so be conservative and return false. */
14746 }
14748 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14749 value is based on the assumption that signed overflow is undefined,
14750 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14751 *STRICT_OVERFLOW_P. */
14753 bool
14756 {
14761 {
14766 strict_overflow_p)
14768 strict_overflow_p));
14770 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14771 both unsigned and at least 2 bits shorter than the result. */
14775 {
14780 {
14784 }
14785 }
14790 {
14791 /* x * x is always non-negative for floating point x
14792 or without overflow. */
14796 {
14801 }
14802 }
14804 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14805 both unsigned and their total bits is shorter than the result. */
14809 {
14828 {
14838 }
14839 }
14845 strict_overflow_p)
14847 strict_overflow_p));
14858 strict_overflow_p)
14860 strict_overflow_p));
14867 strict_overflow_p);
14870 }
14872 /* We don't know sign of `t', so be conservative and return false. */
14874 }
14876 /* Return true if T is known to be non-negative. If the return
14877 value is based on the assumption that signed overflow is undefined,
14878 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14879 *STRICT_OVERFLOW_P. */
14881 bool
14883 {
14888 {
14900 strict_overflow_p)
14902 strict_overflow_p));
14906 }
14907 /* We don't know sign of `t', so be conservative and return false. */
14909 }
14911 /* Return true if T is known to be non-negative. If the return
14912 value is based on the assumption that signed overflow is undefined,
14913 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14914 *STRICT_OVERFLOW_P. */
14916 bool
14919 {
14922 {
14942 /* Always true. */
14946 /* sqrt(-0.0) is -0.0. */
14950 strict_overflow_p);
14987 /* True if the 1st argument is nonnegative. */
14989 strict_overflow_p);
14992 /* True if the 1st OR 2nd arguments are nonnegative. */
14994 strict_overflow_p)
14996 strict_overflow_p)));
14999 /* True if the 1st AND 2nd arguments are nonnegative. */
15001 strict_overflow_p)
15003 strict_overflow_p)));
15006 /* True if the 2nd argument is nonnegative. */
15008 strict_overflow_p);
15011 /* True if the 1st argument is nonnegative or the second
15012 argument is an even integer. */
15017 strict_overflow_p);
15020 /* True if the 1st argument is nonnegative or the second
15021 argument is an even integer valued real. */
15023 {
15024 REAL_VALUE_TYPE c;
15025 HOST_WIDE_INT n;
15030 {
15031 REAL_VALUE_TYPE cint;
15035 }
15036 }
15038 strict_overflow_p);
15042 }
15044 type);
15045 }
15047 /* Return true if T is known to be non-negative. If the return
15048 value is based on the assumption that signed overflow is undefined,
15049 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15050 *STRICT_OVERFLOW_P. */
15052 static bool
15054 {
15060 {
15062 {
15066 /* If the initializer is non-void, then it's a normal expression
15067 that will be assigned to the slot. */
15071 /* Otherwise, the initializer sets the slot in some way. One common
15072 way is an assignment statement at the end of the initializer. */
15074 {
15082 else
15084 }
15088 strict_overflow_p);
15091 }
15094 {
15100 arg0,
15101 arg1,
15102 strict_overflow_p);
15103 }
15107 strict_overflow_p);
15110 strict_overflow_p);
15113 strict_overflow_p);
15118 }
15120 /* We don't know sign of `t', so be conservative and return false. */
15122 }
15124 /* Return true if T is known to be non-negative. If the return
15125 value is based on the assumption that signed overflow is undefined,
15126 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15127 *STRICT_OVERFLOW_P. */
15129 bool
15131 {
15138 {
15145 strict_overflow_p);
15151 strict_overflow_p);
15160 }
15163 {
15171 strict_overflow_p);
15176 strict_overflow_p);
15189 }
15190 }
15192 /* Return true if `t' is known to be non-negative. Handle warnings
15193 about undefined signed overflow. */
15195 bool
15197 {
15204 "determining that expression is always "
15206 WARN_STRICT_OVERFLOW_MISC);
15208 }
15211 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15212 For floating point we further ensure that T is not denormal.
15213 Similar logic is present in nonzero_address in rtlanal.h.
15215 If the return value is based on the assumption that signed overflow
15216 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15217 change *STRICT_OVERFLOW_P. */
15219 bool
15222 {
15224 {
15227 strict_overflow_p);
15230 {
15236 strict_overflow_p));
15237 }
15242 strict_overflow_p);
15246 }
15249 }
15251 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15252 For floating point we further ensure that T is not denormal.
15253 Similar logic is present in nonzero_address in rtlanal.h.
15255 If the return value is based on the assumption that signed overflow
15256 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15257 change *STRICT_OVERFLOW_P. */
15259 bool
15261 tree type,
15262 tree op0,
15264 {
15267 {
15271 {
15272 /* With the presence of negative values it is hard
15273 to say something. */
15280 /* One of operands must be positive and the other non-negative. */
15281 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15282 overflows, on a twos-complement machine the sum of two
15283 nonnegative numbers can never be zero. */
15285 strict_overflow_p)
15287 strict_overflow_p));
15288 }
15293 {
15295 strict_overflow_p)
15297 strict_overflow_p))
15298 {
15301 }
15302 }
15311 {
15314 }
15321 {
15325 /* When both operands are nonzero, then MAX must be too. */
15327 strict_overflow_p))
15330 /* MAX where operand 0 is positive is positive. */
15332 strict_overflow_p);
15333 }
15334 /* MAX where operand 1 is positive is positive. */
15339 {
15343 }
15348 strict_overflow_p)
15350 strict_overflow_p));
15354 }
15357 }
15359 /* Return true when T is an address and is known to be nonzero.
15360 For floating point we further ensure that T is not denormal.
15361 Similar logic is present in nonzero_address in rtlanal.h.
15363 If the return value is based on the assumption that signed overflow
15364 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15365 change *STRICT_OVERFLOW_P. */
15367 bool
15369 {
15372 {
15377 {
15386 /* For objects in symbol table check if we know they are non-zero.
15387 Don't do anything for variables and functions before symtab is built;
15388 it is quite possible that they will be declared weak later. */
15390 {
15396 else
15398 }
15400 /* Function local objects are never NULL. */
15407 /* Constants are never weak. */
15412 }
15420 {
15424 }
15429 }
15431 }
15433 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15434 attempt to fold the expression to a constant without modifying TYPE,
15435 OP0 or OP1.
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 /* Given the components of a unary expression CODE, TYPE and OP0,
15449 attempt to fold the expression to a constant without modifying
15450 TYPE or OP0.
15452 If the expression could be simplified to a constant, then return
15453 the constant. If the expression would not be simplified to a
15454 constant, then return NULL_TREE. */
15456 tree
15458 {
15461 }
15463 /* If EXP represents referencing an element in a constant string
15464 (either via pointer arithmetic or array indexing), return the
15465 tree representing the value accessed, otherwise return NULL. */
15467 tree
15469 {
15473 {
15475 tree index;
15476 tree string;
15481 else
15482 {
15486 /* Optimize the special-case of a zero lower bound.
15488 We convert the low_bound to sizetype to avoid some problems
15489 with constant folding. (E.g. suppose the lower bound is 1,
15490 and its mode is QI. Without the conversion,l (ARRAY
15491 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15492 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15498 }
15511 }
15513 }
15515 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15516 an integer constant, real, or fixed-point constant.
15518 TYPE is the type of the result. */
15520 static tree
15522 {
15526 {
15528 {
15535 }
15542 {
15543 FIXED_VALUE_TYPE f;
15548 /* Propagate overflow flags. */
15552 }
15556 }
15559 }
15561 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15562 an integer constant or real constant.
15564 TYPE is the type of the result. */
15566 tree
15568 {
15572 {
15574 {
15575 /* If the value is unsigned or non-negative, then the absolute value
15576 is the same as the ordinary value. */
15580 /* If the value is negative, then the absolute value is
15581 its negation. */
15582 else
15583 {
15588 }
15589 }
15595 else
15601 }
15604 }
15606 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15607 constant. TYPE is the type of the result. */
15609 static tree
15611 {
15615 }
15617 /* Given CODE, a relational operator, the target type, TYPE and two
15618 constant operands OP0 and OP1, return the result of the
15619 relational operation. If the result is not a compile time
15620 constant, then return NULL_TREE. */
15622 static tree
15624 {
15627 /* From here on, the only cases we handle are when the result is
15628 known to be a constant. */
15631 {
15635 /* Handle the cases where either operand is a NaN. */
15637 {
15639 {
15667 }
15670 }
15673 }
15676 {
15680 }
15682 /* Handle equality/inequality of complex constants. */
15684 {
15695 else
15697 }
15700 {
15707 {
15719 }
15722 }
15724 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15726 To compute GT, swap the arguments and do LT.
15727 To compute GE, do LT and invert the result.
15728 To compute LE, swap the arguments, do LT and invert the result.
15729 To compute NE, do EQ and invert the result.
15731 Therefore, the code below must handle only EQ and LT. */
15734 {
15739 }
15741 /* Note that it is safe to invert for real values here because we
15742 have already handled the one case that it matters. */
15746 {
15749 }
15751 /* Compute a result for LT or EQ if args permit;
15752 Otherwise return T. */
15754 {
15757 else
15759 }
15760 else
15766 }
15768 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15769 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15770 itself. */
15772 tree
15774 {
15775 /* If the expression does not have side effects then we don't have to wrap
15776 it with a cleanup point expression. */
15780 /* If the expression is a return, check to see if the expression inside the
15781 return has no side effects or the right hand side of the modify expression
15782 inside the return. If either don't have side effects set we don't need to
15783 wrap the expression in a cleanup point expression. Note we don't check the
15784 left hand side of the modify because it should always be a return decl. */
15786 {
15793 }
15796 }
15798 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15799 of an indirection through OP0, or NULL_TREE if no simplification is
15800 possible. */
15802 tree
15804 {
15806 tree subtype;
15814 {
15817 /* *&CONST_DECL -> to the value of the const decl. */
15820 /* *&p => p; make sure to handle *&"str"[cst] here. */
15822 {
15826 else
15828 }
15829 /* *(foo *)&fooarray => fooarray[0] */
15832 && (!in_gimple_form
15834 {
15844 }
15845 /* *(foo *)&complexfoo => __real__ complexfoo */
15849 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15852 {
15856 }
15857 }
15861 {
15867 {
15868 tree op00type;
15872 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15875 {
15887 }
15888 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15891 {
15895 }
15896 /* ((foo *)&fooarray)[1] => fooarray[1] */
15899 {
15909 }
15910 }
15911 }
15913 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15916 && (!in_gimple_form
15918 {
15919 tree type_domain;
15929 NULL_TREE);
15930 }
15933 }
15935 /* Builds an expression for an indirection through T, simplifying some
15936 cases. */
15938 tree
15940 {
15948 }
15950 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15952 tree
15954 {
15959 else
15961 }
15963 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15964 whose result is ignored. The type of the returned tree need not be
15965 the same as the original expression. */
15967 tree
15969 {
15975 {
15986 else
15992 {
16008 }
16013 }
16014 }
16016 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16018 tree
16020 {
16026 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16027 have to do anything. Only do this when we are not given a const,
16028 because in that case, this check is more expensive than just
16029 doing it. */
16031 {
16036 }
16038 /* If divisor is a power of two, simplify this to bit manipulation. */
16040 {
16042 {
16056 }
16057 else
16058 {
16059 tree t;
16065 }
16066 }
16067 else
16068 {
16073 }
16076 }
16078 /* Likewise, but round down. */
16080 tree
16082 {
16089 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16090 have to do anything. Only do this when we are not given a const,
16091 because in that case, this check is more expensive than just
16092 doing it. */
16094 {
16099 }
16101 /* If divisor is a power of two, simplify this to bit manipulation. */
16103 {
16104 tree t;
16108 }
16109 else
16110 {
16115 }
16118 }
16120 /* Returns the pointer to the base of the object addressed by EXP and
16121 extracts the information about the offset of the access, storing it
16122 to PBITPOS and POFFSET. */
16124 static tree
16127 {
16128 tree core;
16129 machine_mode mode;
16131 HOST_WIDE_INT bitsize;
16135 {
16140 }
16141 else
16142 {
16146 }
16149 }
16151 /* Returns true if addresses of E1 and E2 differ by a constant, false
16152 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16154 bool
16156 {
16170 {
16180 }
16182 {
16183 /* If only one of the offsets is non-constant, the difference cannot
16184 be a constant. */
16186 }
16187 else
16192 }
16194 /* Simplify the floating point expression EXP when the sign of the
16195 result is not significant. Return NULL_TREE if no simplification
16196 is possible. */
16198 tree
16200 {
16205 {
16241 {
16244 {
16246 /* Strip copysign function call, return the 1st argument. */
16252 /* Strip sign ops from the argument of "odd" math functions. */
16254 {
16258 }
16260 }
16261 }
16266 }
16268 }
16270 /* Return OFF converted to a pointer offset type suitable as offset for
16271 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16272 tree
16274 {
16276 }
16278 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16279 tree
16281 {
16284 }
16286 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16287 tree
16289 {
16292 }