| blob | 756f469d0387a1ad5bca28ede7fbc229618395fc |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
131 HOST_WIDE_INT *,
162 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
163 Otherwise, return LOC. */
165 static location_t
167 {
170 }
172 /* Similar to protected_set_expr_location, but never modify x in place,
173 if location can and needs to be set, unshare it. */
177 {
183 {
186 }
188 }
189 \f
190 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
191 division and returns the quotient. Otherwise returns
192 NULL_TREE. */
194 tree
196 {
197 widest_int quo;
204 }
205 \f
206 /* This is nonzero if we should defer warnings about undefined
207 overflow. This facility exists because these warnings are a
208 special case. The code to estimate loop iterations does not want
209 to issue any warnings, since it works with expressions which do not
210 occur in user code. Various bits of cleanup code call fold(), but
211 only use the result if it has certain characteristics (e.g., is a
212 constant); that code only wants to issue a warning if the result is
213 used. */
217 /* If a warning about undefined overflow is deferred, this is the
218 warning. Note that this may cause us to turn two warnings into
219 one, but that is fine since it is sufficient to only give one
220 warning per expression. */
224 /* If a warning about undefined overflow is deferred, this is the
225 level at which the warning should be emitted. */
229 /* Start deferring overflow warnings. We could use a stack here to
230 permit nested calls, but at present it is not necessary. */
232 void
234 {
236 }
238 /* Stop deferring overflow warnings. If there is a pending warning,
239 and ISSUE is true, then issue the warning if appropriate. STMT is
240 the statement with which the warning should be associated (used for
241 location information); STMT may be NULL. CODE is the level of the
242 warning--a warn_strict_overflow_code value. This function will use
243 the smaller of CODE and the deferred code when deciding whether to
244 issue the warning. CODE may be zero to mean to always use the
245 deferred code. */
247 void
249 {
251 location_t locus;
256 {
262 }
273 /* Use the smallest code level when deciding to issue the
274 warning. */
283 else
286 }
288 /* Stop deferring overflow warnings, ignoring any deferred
289 warnings. */
291 void
293 {
295 }
297 /* Whether we are deferring overflow warnings. */
299 bool
301 {
303 }
305 /* This is called when we fold something based on the fact that signed
306 overflow is undefined. */
308 static void
310 {
312 {
315 {
318 }
319 }
322 }
323 \f
324 /* Return true if the built-in mathematical function specified by CODE
325 is odd, i.e. -f(x) == f(-x). */
327 static bool
329 {
331 {
365 }
367 }
369 /* Check whether we may negate an integer constant T without causing
370 overflow. */
372 bool
374 {
375 tree type;
384 }
386 /* Determine whether an expression T can be cheaply negated using
387 the function negate_expr without introducing undefined overflow. */
389 static bool
391 {
392 tree type;
401 {
406 /* Check that -CST will not overflow type. */
417 /* We want to canonicalize to positive real constants. Pretend
418 that only negative ones can be easily negated. */
426 {
437 }
450 /* -(A + B) -> (-B) - A. */
455 /* -(A + B) -> (-A) - B. */
459 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
469 /* Fall through. */
480 /* In general we can't negate A / B, because if A is INT_MIN and
481 B is 1, we may turn this into INT_MIN / -1 which is undefined
482 and actually traps on some architectures. But if overflow is
483 undefined, we can negate, because - (INT_MIN / 1) is an
484 overflow. */
486 {
489 /* If overflow is undefined then we have to be careful because
490 we ask whether it's ok to associate the negate with the
491 division which is not ok for example for
492 -((a - b) / c) where (-(a - b)) / c may invoke undefined
493 overflow because of negating INT_MIN. So do not use
494 negate_expr_p here but open-code the two important cases. */
499 }
505 /* Negate -((double)float) as (double)(-float). */
507 {
511 }
515 /* Negate -f(x) as f(-x). */
521 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
523 {
527 }
532 }
534 }
536 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
537 simplification is possible.
538 If negate_expr_p would return true for T, NULL_TREE will never be
539 returned. */
541 static tree
543 {
545 tree tem;
548 {
549 /* Convert - (~A) to A + 1. */
565 /* Two's complement FP formats, such as c4x, may overflow. */
575 {
584 }
588 {
593 {
597 }
600 }
621 {
622 /* -(A + B) -> (-B) - A. */
626 {
630 }
632 /* -(A + B) -> (-A) - B. */
634 {
638 }
639 }
643 /* - (A - B) -> B - A */
655 /* Fall through. */
659 {
668 }
674 /* In general we can't negate A / B, because if A is INT_MIN and
675 B is 1, we may turn this into INT_MIN / -1 which is undefined
676 and actually traps on some architectures. But if overflow is
677 undefined, we can negate, because - (INT_MIN / 1) is an
678 overflow. */
680 {
685 {
692 }
693 /* If overflow is undefined then we have to be careful because
694 we ask whether it's ok to associate the negate with the
695 division which is not ok for example for
696 -((a - b) / c) where (-(a - b)) / c may invoke undefined
697 overflow because of negating INT_MIN. So do not use
698 negate_expr_p here but open-code the two important cases. */
707 }
711 /* Convert -((double)float) into (double)(-float). */
713 {
717 }
721 /* Negate -f(x) as f(-x). */
724 {
730 }
734 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
736 {
739 {
746 }
747 }
752 }
755 }
757 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
758 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
759 return NULL_TREE. */
761 static tree
763 {
765 location_t loc;
778 }
779 \f
780 /* Split a tree IN into a constant, literal and variable parts that could be
781 combined with CODE to make IN. "constant" means an expression with
782 TREE_CONSTANT but that isn't an actual constant. CODE must be a
783 commutative arithmetic operation. Store the constant part into *CONP,
784 the literal in *LITP and return the variable part. If a part isn't
785 present, set it to null. If the tree does not decompose in this way,
786 return the entire tree as the variable part and the other parts as null.
788 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
789 case, we negate an operand that was subtracted. Except if it is a
790 literal for which we use *MINUS_LITP instead.
792 If NEGATE_P is true, we are negating all of IN, again except a literal
793 for which we use *MINUS_LITP instead.
795 If IN is itself a literal or constant, return it as appropriate.
797 Note that we do not guarantee that any of the three values will be the
798 same type as IN, but they will have the same signedness and mode. */
800 static tree
803 {
810 /* Strip any conversions that don't change the machine mode or signedness. */
819 /* We can associate addition and subtraction together (even
820 though the C standard doesn't say so) for integers because
821 the value is not affected. For reals, the value might be
822 affected, so we can't. */
825 {
831 /* First see if either of the operands is a literal, then a constant. */
844 /* If we haven't dealt with either operand, this is not a case we can
845 decompose. Otherwise, VAR is either of the ones remaining, if any. */
850 else
853 /* Now do any needed negations. */
860 }
863 {
864 /* -X - 1 is folded to ~X, undo that here. */
867 }
870 else
874 {
881 }
884 }
886 /* Re-associate trees split by the above function. T1 and T2 are
887 either expressions to associate or null. Return the new
888 expression, if any. LOC is the location of the new expression. If
889 we build an operation, do it in TYPE and with CODE. */
891 static tree
893 {
899 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
900 try to fold this since we will have infinite recursion. But do
901 deal with any NEGATE_EXPRs. */
904 {
906 {
919 }
921 {
924 }
928 }
932 }
933 \f
934 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
935 for use in int_const_binop, size_binop and size_diffop. */
937 static bool
939 {
946 {
955 }
960 }
963 /* Combine two integer constants ARG1 and ARG2 under operation CODE
964 to produce a new constant. Return NULL_TREE if we don't know how
965 to evaluate CODE at compile-time. */
967 static tree
970 {
971 wide_int res;
972 tree t;
981 {
997 {
1001 else
1003 }
1006 /* It's unclear from the C standard whether shifts can overflow.
1007 The following code ignores overflow; perhaps a C standard
1008 interpretation ruling is needed. */
1010 else
1017 {
1021 else
1023 }
1027 else
1106 }
1114 }
1116 tree
1118 {
1120 }
1122 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1123 constant. We assume ARG1 and ARG2 have the same data type, or at least
1124 are the same kind of constant and the same machine mode. Return zero if
1125 combining the constants is not allowed in the current operating mode. */
1127 static tree
1129 {
1130 /* Sanity check for the recursive cases. */
1141 {
1142 machine_mode mode;
1143 REAL_VALUE_TYPE d1;
1144 REAL_VALUE_TYPE d2;
1145 REAL_VALUE_TYPE value;
1146 REAL_VALUE_TYPE result;
1150 /* The following codes are handled by real_arithmetic. */
1152 {
1163 }
1171 /* Don't perform operation if we honor signaling NaNs and
1172 either operand is a NaN. */
1177 /* Don't perform operation if it would raise a division
1178 by zero exception. */
1184 /* If either operand is a NaN, just return it. Otherwise, set up
1185 for floating-point trap; we return an overflow. */
1194 /* Don't constant fold this floating point operation if
1195 the result has overflowed and flag_trapping_math. */
1203 /* Don't constant fold this floating point operation if the
1204 result may dependent upon the run-time rounding mode and
1205 flag_rounding_math is set, or if GCC's software emulation
1206 is unable to accurately represent the result. */
1216 }
1219 {
1220 FIXED_VALUE_TYPE f1;
1221 FIXED_VALUE_TYPE f2;
1222 FIXED_VALUE_TYPE result;
1227 /* The following codes are handled by fixed_arithmetic. */
1229 {
1239 {
1244 }
1249 }
1256 /* Propagate overflow flags. */
1260 }
1263 {
1272 {
1283 mpc_mul);
1297 mpc_div);
1298 /* Fallthru ... */
1304 {
1305 /* Keep this algorithm in sync with
1306 tree-complex.c:expand_complex_div_straight().
1308 Expand complex division to scalars, straightforward algorithm.
1309 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1310 t = br*br + bi*bi
1311 */
1312 tree magsquared
1316 tree t1
1320 tree t2
1327 }
1328 else
1329 {
1330 /* Keep this algorithm in sync with
1331 tree-complex.c:expand_complex_div_wide().
1333 Expand complex division to scalars, modified algorithm to minimize
1334 overflow with wide input ranges. */
1340 {
1341 /* In the TRUE branch, we compute
1342 ratio = br/bi;
1343 div = (br * ratio) + bi;
1344 tr = (ar * ratio) + ai;
1345 ti = (ai * ratio) - ar;
1346 tr = tr / div;
1347 ti = ti / div; */
1358 }
1359 else
1360 {
1361 /* In the FALSE branch, we compute
1362 ratio = d/c;
1363 divisor = (d * ratio) + c;
1364 tr = (b * ratio) + a;
1365 ti = b - (a * ratio);
1366 tr = tr / div;
1367 ti = ti / div; */
1379 }
1380 }
1385 }
1389 }
1393 {
1399 {
1405 /* It is possible that const_binop cannot handle the given
1406 code and return NULL_TREE */
1409 }
1412 }
1414 /* Shifts allow a scalar offset for a vector. */
1417 {
1423 {
1429 unsigned HOST_WIDE_INT innerc
1434 /* The direction of VEC_RSHIFT_EXPR is endian dependent.
1435 For reductions, if !BYTES_BIG_ENDIAN then compiler picks first
1436 vector element, but last element if BYTES_BIG_ENDIAN. */
1441 {
1444 else
1446 }
1447 }
1448 else
1450 {
1455 /* It is possible that const_binop cannot handle the given
1456 code and return NULL_TREE */
1459 }
1462 }
1464 }
1466 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1467 indicates which particular sizetype to create. */
1469 tree
1471 {
1473 }
1474 \f
1475 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1476 is a tree code. The type of the result is taken from the operands.
1477 Both must be equivalent integer types, ala int_binop_types_match_p.
1478 If the operands are constant, so is the result. */
1480 tree
1482 {
1491 /* Handle the special case of two integer constants faster. */
1493 {
1494 /* And some specific cases even faster than that. */
1496 {
1501 }
1503 {
1506 }
1508 {
1511 }
1513 /* Handle general case of two integer constants. For sizetype
1514 constant calculations we always want to know about overflow,
1515 even in the unsigned case. */
1517 }
1520 }
1522 /* Given two values, either both of sizetype or both of bitsizetype,
1523 compute the difference between the two values. Return the value
1524 in signed type corresponding to the type of the operands. */
1526 tree
1528 {
1530 tree ctype;
1535 /* If the type is already signed, just do the simple thing. */
1543 else
1546 /* If either operand is not a constant, do the conversions to the signed
1547 type and subtract. The hardware will do the right thing with any
1548 overflow in the subtraction. */
1554 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1555 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1556 overflow) and negate (which can't either). Special-case a result
1557 of zero while we're here. */
1563 else
1567 MINUS_EXPR,
1569 }
1570 \f
1571 /* A subroutine of fold_convert_const handling conversions of an
1572 INTEGER_CST to another integer type. */
1574 static tree
1576 {
1577 /* Given an integer constant, make new constant with new type,
1578 appropriately sign-extended or truncated. Use widest_int
1579 so that any extension is done according ARG1's type. */
1583 }
1585 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1586 to an integer type. */
1588 static tree
1590 {
1592 tree t;
1594 /* The following code implements the floating point to integer
1595 conversion rules required by the Java Language Specification,
1596 that IEEE NaNs are mapped to zero and values that overflow
1597 the target precision saturate, i.e. values greater than
1598 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1599 are mapped to INT_MIN. These semantics are allowed by the
1600 C and C++ standards that simply state that the behavior of
1601 FP-to-integer conversion is unspecified upon overflow. */
1603 wide_int val;
1604 REAL_VALUE_TYPE r;
1608 {
1615 }
1617 /* If R is NaN, return zero and show we have an overflow. */
1619 {
1622 }
1624 /* See if R is less than the lower bound or greater than the
1625 upper bound. */
1628 {
1632 {
1635 }
1636 }
1639 {
1642 {
1645 {
1648 }
1649 }
1650 }
1657 }
1659 /* A subroutine of fold_convert_const handling conversions of a
1660 FIXED_CST to an integer type. */
1662 static tree
1664 {
1665 tree t;
1669 /* Right shift FIXED_CST to temp by fbit. */
1673 {
1675 HOST_BITS_PER_DOUBLE_INT,
1678 /* Left shift temp to temp_trunc by fbit. */
1680 HOST_BITS_PER_DOUBLE_INT,
1682 }
1683 else
1684 {
1687 }
1689 /* If FIXED_CST is negative, we need to round the value toward 0.
1690 By checking if the fractional bits are not zero to add 1 to temp. */
1696 /* Given a fixed-point constant, make new constant with new type,
1697 appropriately sign-extended or truncated. */
1705 }
1707 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1708 to another floating point type. */
1710 static tree
1712 {
1713 REAL_VALUE_TYPE value;
1714 tree t;
1719 /* If converting an infinity or NAN to a representation that doesn't
1720 have one, set the overflow bit so that we can produce some kind of
1721 error message at the appropriate point if necessary. It's not the
1722 most user-friendly message, but it's better than nothing. */
1729 /* Regular overflow, conversion produced an infinity in a mode that
1730 can't represent them. */
1735 else
1738 }
1740 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1741 to a floating point type. */
1743 static tree
1745 {
1746 REAL_VALUE_TYPE value;
1747 tree t;
1754 }
1756 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1757 to another fixed-point type. */
1759 static tree
1761 {
1762 FIXED_VALUE_TYPE value;
1763 tree t;
1770 /* Propagate overflow flags. */
1774 }
1776 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
1777 to a fixed-point type. */
1779 static tree
1781 {
1782 FIXED_VALUE_TYPE value;
1783 tree t;
1785 double_int di;
1792 else
1800 /* Propagate overflow flags. */
1804 }
1806 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1807 to a fixed-point type. */
1809 static tree
1811 {
1812 FIXED_VALUE_TYPE value;
1813 tree t;
1821 /* Propagate overflow flags. */
1825 }
1827 /* Attempt to fold type conversion operation CODE of expression ARG1 to
1828 type TYPE. If no simplification can be done return NULL_TREE. */
1830 static tree
1832 {
1838 {
1845 }
1847 {
1854 }
1856 {
1863 }
1865 }
1867 /* Construct a vector of zero elements of vector type TYPE. */
1869 static tree
1871 {
1872 tree t;
1876 }
1878 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
1880 bool
1882 {
1897 {
1916 }
1917 }
1919 /* Convert expression ARG to type TYPE. Used by the middle-end for
1920 simple conversions in preference to calling the front-end's convert. */
1922 tree
1924 {
1926 tree tem;
1937 {
1940 /* Handle conversions between pointers to different address spaces. */
1945 /* fall through */
1950 {
1954 }
1968 {
1972 }
1974 {
1978 }
1980 {
1984 }
1987 {
2005 }
2010 {
2014 }
2017 {
2031 }
2035 {
2044 integer_zero_node));
2046 {
2050 {
2056 }
2064 }
2068 }
2086 }
2087 fold_convert_exit:
2090 }
2091 \f
2092 /* Return false if expr can be assumed not to be an lvalue, true
2093 otherwise. */
2095 static bool
2097 {
2098 /* We only need to wrap lvalue tree codes. */
2100 {
2131 /* Assume the worst for front-end tree codes. */
2135 }
2138 }
2140 /* Return an expr equal to X but certainly not valid as an lvalue. */
2142 tree
2144 {
2145 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2146 us. */
2153 }
2155 /* When pedantic, return an expr equal to X but certainly not valid as a
2156 pedantic lvalue. Otherwise, return X. */
2158 static tree
2160 {
2162 }
2163 \f
2164 /* Given a tree comparison code, return the code that is the logical inverse.
2165 It is generally not safe to do this for floating-point comparisons, except
2166 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2167 ERROR_MARK in this case. */
2169 enum tree_code
2171 {
2177 {
2208 }
2209 }
2211 /* Similar, but return the comparison that results if the operands are
2212 swapped. This is safe for floating-point. */
2214 enum tree_code
2216 {
2218 {
2244 }
2245 }
2248 /* Convert a comparison tree code from an enum tree_code representation
2249 into a compcode bit-based encoding. This function is the inverse of
2250 compcode_to_comparison. */
2252 static enum comparison_code
2254 {
2256 {
2287 }
2288 }
2290 /* Convert a compcode bit-based encoding of a comparison operator back
2291 to GCC's enum tree_code representation. This function is the
2292 inverse of comparison_to_compcode. */
2294 static enum tree_code
2296 {
2298 {
2329 }
2330 }
2332 /* Return a tree for the comparison which is the combination of
2333 doing the AND or OR (depending on CODE) of the two operations LCODE
2334 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2335 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2336 if this makes the transformation invalid. */
2338 tree
2343 {
2350 {
2361 }
2364 {
2365 /* Eliminate unordered comparisons, as well as LTGT and ORD
2366 which are not used unless the mode has NaNs. */
2372 }
2374 {
2375 /* Check that the original operation and the optimized ones will trap
2376 under the same condition. */
2387 /* In a short-circuited boolean expression the LHS might be
2388 such that the RHS, if evaluated, will never trap. For
2389 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2390 if neither x nor y is NaN. (This is a mixed blessing: for
2391 example, the expression above will never trap, hence
2392 optimizing it to x < y would be invalid). */
2397 /* If the comparison was short-circuited, and only the RHS
2398 trapped, we may now generate a spurious trap. */
2403 /* If we changed the conditions that cause a trap, we lose. */
2406 }
2412 else
2413 {
2418 }
2419 }
2420 \f
2421 /* Return nonzero if two operands (typically of the same tree node)
2422 are necessarily equal. If either argument has side-effects this
2423 function returns zero. FLAGS modifies behavior as follows:
2425 If OEP_ONLY_CONST is set, only return nonzero for constants.
2426 This function tests whether the operands are indistinguishable;
2427 it does not test whether they are equal using C's == operation.
2428 The distinction is important for IEEE floating point, because
2429 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2430 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2432 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2433 even though it may hold multiple values during a function.
2434 This is because a GCC tree node guarantees that nothing else is
2435 executed between the evaluation of its "operands" (which may often
2436 be evaluated in arbitrary order). Hence if the operands themselves
2437 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2438 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2439 unset means assuming isochronic (or instantaneous) tree equivalence.
2440 Unless comparing arbitrary expression trees, such as from different
2441 statements, this flag can usually be left unset.
2443 If OEP_PURE_SAME is set, then pure functions with identical arguments
2444 are considered the same. It is used when the caller has other ways
2445 to ensure that global memory is unchanged in between. */
2447 int
2449 {
2450 /* If either is ERROR_MARK, they aren't equal. */
2456 /* Similar, if either does not have a type (like a released SSA name),
2457 they aren't equal. */
2461 /* Check equality of integer constants before bailing out due to
2462 precision differences. */
2466 /* If both types don't have the same signedness, then we can't consider
2467 them equal. We must check this before the STRIP_NOPS calls
2468 because they may change the signedness of the arguments. As pointers
2469 strictly don't have a signedness, require either two pointers or
2470 two non-pointers as well. */
2475 /* We cannot consider pointers to different address space equal. */
2481 /* If both types don't have the same precision, then it is not safe
2482 to strip NOPs. */
2490 /* In case both args are comparisons but with different comparison
2491 code, try to swap the comparison operands of one arg to produce
2492 a match and compare that variant. */
2496 {
2504 }
2507 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2511 /* This is needed for conversions and for COMPONENT_REF.
2512 Might as well play it safe and always test this. */
2518 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2519 We don't care about side effects in that case because the SAVE_EXPR
2520 takes care of that for us. In all other cases, two expressions are
2521 equal if they have no side effects. If we have two identical
2522 expressions with side effects that should be treated the same due
2523 to the only side effects being identical SAVE_EXPR's, that will
2524 be detected in the recursive calls below.
2525 If we are taking an invariant address of two identical objects
2526 they are necessarily equal as well. */
2533 /* Next handle constant cases, those for which we can return 1 even
2534 if ONLY_CONST is set. */
2537 {
2552 {
2553 /* If we do not distinguish between signed and unsigned zero,
2554 consider them equal. */
2557 }
2561 {
2568 {
2572 }
2574 }
2578 flags)
2580 flags));
2594 }
2599 /* Define macros to test an operand from arg0 and arg1 for equality and a
2600 variant that allows null and views null as being different from any
2601 non-null value. In the latter case, if either is null, the both
2602 must be; otherwise, do the normal comparison. */
2603 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2604 TREE_OPERAND (arg1, N), flags)
2606 #define OP_SAME_WITH_NULL(N) \
2607 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2608 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2611 {
2613 /* Two conversions are equal only if signedness and modes match. */
2615 {
2616 CASE_CONVERT:
2624 }
2634 /* For commutative ops, allow the other order. */
2642 /* If either of the pointer (or reference) expressions we are
2643 dereferencing contain a side effect, these cannot be equal,
2644 but their addresses can be. */
2651 {
2662 /* Require equal extra operands and then fall through to MEM_REF
2663 handling of the two common operands. */
2668 /* Fallthru. */
2671 /* Require equal access sizes, and similar pointer types.
2672 We can have incomplete types for array references of
2673 variable-sized arrays from the Fortran frontend
2674 though. Also verify the types are compatible. */
2681 && alias_ptr_types_compatible_p
2688 /* Operands 2 and 3 may be null.
2689 Compare the array index by value if it is constant first as we
2690 may have different types but same value here. */
2701 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2702 may be NULL when we're called to compare MEM_EXPRs. */
2717 }
2721 {
2735 /* The multiplcation operands are commutative. */
2736 /* FALLTHRU */
2744 /* Otherwise take into account this is a commutative operation. */
2757 }
2761 {
2763 /* If the CALL_EXPRs call different functions, then they
2764 clearly can not be equal. */
2766 flags))
2769 {
2773 else
2777 }
2779 /* Now see if all the arguments are the same. */
2780 {
2791 /* If we get here and both argument lists are exhausted
2792 then the CALL_EXPRs are equal. */
2794 }
2797 }
2800 /* Consider __builtin_sqrt equal to sqrt. */
2808 }
2810 #undef OP_SAME
2811 #undef OP_SAME_WITH_NULL
2812 }
2813 \f
2814 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2815 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2817 When in doubt, return 0. */
2819 static int
2821 {
2833 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2834 and see if the inner values are the same. This removes any
2835 signedness comparison, which doesn't matter here. */
2842 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2843 actual comparison operand, ARG0.
2845 First throw away any conversions to wider types
2846 already present in the operands. */
2855 {
2858 /* Make sure shorter operand is extended the right way
2859 to match the longer operand. */
2865 }
2868 }
2869 \f
2870 /* See if ARG is an expression that is either a comparison or is performing
2871 arithmetic on comparisons. The comparisons must only be comparing
2872 two different values, which will be stored in *CVAL1 and *CVAL2; if
2873 they are nonzero it means that some operands have already been found.
2874 No variables may be used anywhere else in the expression except in the
2875 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2876 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2878 If this is true, return 1. Otherwise, return zero. */
2880 static int
2882 {
2886 /* We can handle some of the tcc_expression cases here. */
2896 {
2897 /* If we've already found a CVAL1 or CVAL2, this expression is
2898 two complex to handle. */
2904 }
2907 {
2930 /* First see if we can handle the first operand, then the second. For
2931 the second operand, we know *CVAL1 can't be zero. It must be that
2932 one side of the comparison is each of the values; test for the
2933 case where this isn't true by failing if the two operands
2934 are the same. */
2943 ;
2947 ;
2948 else
2952 ;
2956 ;
2957 else
2964 }
2965 }
2966 \f
2967 /* ARG is a tree that is known to contain just arithmetic operations and
2968 comparisons. Evaluate the operations in the tree substituting NEW0 for
2969 any occurrence of OLD0 as an operand of a comparison and likewise for
2970 NEW1 and OLD1. */
2972 static tree
2975 {
2980 /* We can handle some of the tcc_expression cases here. */
2988 {
3003 {
3022 }
3023 /* Fall through - ??? */
3026 {
3030 /* We need to check both for exact equality and tree equality. The
3031 former will be true if the operand has a side-effect. In that
3032 case, we know the operand occurred exactly once. */
3045 }
3049 }
3050 }
3051 \f
3052 /* Return a tree for the case when the result of an expression is RESULT
3053 converted to TYPE and OMITTED was previously an operand of the expression
3054 but is now not needed (e.g., we folded OMITTED * 0).
3056 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3057 the conversion of RESULT to TYPE. */
3059 tree
3061 {
3064 /* If the resulting operand is an empty statement, just return the omitted
3065 statement casted to void. */
3075 }
3077 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3079 static tree
3081 tree omitted)
3082 {
3085 /* If the resulting operand is an empty statement, just return the omitted
3086 statement casted to void. */
3096 }
3098 /* Return a tree for the case when the result of an expression is RESULT
3099 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3100 of the expression but are now not needed.
3102 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3103 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3104 evaluated before OMITTED2. Otherwise, if neither has side effects,
3105 just do the conversion of RESULT to TYPE. */
3107 tree
3110 {
3119 }
3121 \f
3122 /* Return a simplified tree node for the truth-negation of ARG. This
3123 never alters ARG itself. We assume that ARG is an operation that
3124 returns a truth value (0 or 1).
3126 FIXME: one would think we would fold the result, but it causes
3127 problems with the dominator optimizer. */
3129 static tree
3131 {
3136 /* If this is a comparison, we can simply invert it, except for
3137 floating-point non-equality comparisons, in which case we just
3138 enclose a TRUTH_NOT_EXPR around what we have. */
3141 {
3144 && flag_trapping_math
3155 }
3158 {
3177 /* Here we can invert either operand. We invert the first operand
3178 unless the second operand is a TRUTH_NOT_EXPR in which case our
3179 result is the XOR of the first operand with the inside of the
3180 negation of the second operand. */
3185 else
3208 {
3215 /* A COND_EXPR may have a throw as one operand, which
3216 then has void type. Just leave void operands
3217 as they are. */
3223 }
3235 CASE_CONVERT:
3239 /* ... fall through ... */
3261 }
3262 }
3264 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3265 assume that ARG is an operation that returns a truth value (0 or 1
3266 for scalars, 0 or -1 for vectors). Return the folded expression if
3267 folding is successful. Otherwise, return NULL_TREE. */
3269 static tree
3271 {
3274 ? BIT_NOT_EXPR
3277 }
3279 /* Return a simplified tree node for the truth-negation of ARG. This
3280 never alters ARG itself. We assume that ARG is an operation that
3281 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3283 tree
3285 {
3291 ? BIT_NOT_EXPR
3294 }
3296 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3297 operands are another bit-wise operation with a common input. If so,
3298 distribute the bit operations to save an operation and possibly two if
3299 constants are involved. For example, convert
3300 (A | B) & (A | C) into A | (B & C)
3301 Further simplification will occur if B and C are constants.
3303 If this optimization cannot be done, 0 will be returned. */
3305 static tree
3308 {
3309 tree common;
3319 {
3323 }
3325 {
3329 }
3331 {
3335 }
3337 {
3341 }
3342 else
3350 }
3352 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3353 with code CODE. This optimization is unsafe. */
3354 static tree
3357 {
3361 /* (A / C) +- (B / C) -> (A +- B) / C. */
3371 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3376 {
3388 }
3391 }
3392 \f
3393 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3394 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3396 static tree
3399 {
3403 {
3410 }
3424 }
3426 /* Optimize a bit-field compare.
3428 There are two cases: First is a compare against a constant and the
3429 second is a comparison of two items where the fields are at the same
3430 bit position relative to the start of a chunk (byte, halfword, word)
3431 large enough to contain it. In these cases we can avoid the shift
3432 implicit in bitfield extractions.
3434 For constants, we emit a compare of the shifted constant with the
3435 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3436 compared. For two fields at the same position, we do the ANDs with the
3437 similar mask and compare the result of the ANDs.
3439 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3440 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3441 are the left and right operands of the comparison, respectively.
3443 If the optimization described above can be done, we return the resulting
3444 tree. Otherwise we return zero. */
3446 static tree
3449 {
3452 tree unsigned_type;
3458 tree mask;
3459 tree offset;
3461 /* Get all the information about the extractions being done. If the bit size
3462 if the same as the size of the underlying object, we aren't doing an
3463 extraction at all and so can do nothing. We also don't want to
3464 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3465 then will no longer be able to replace it. */
3473 {
3474 /* If this is not a constant, we can only do something if bit positions,
3475 sizes, and signedness are the same. */
3483 }
3485 /* See if we can find a mode to refer to this field. We should be able to,
3486 but fail if we can't. */
3495 /* Set signed and unsigned types of the precision of this mode for the
3496 shifts below. */
3499 /* Compute the bit position and size for the new reference and our offset
3500 within it. If the new reference is the same size as the original, we
3501 won't optimize anything, so return zero. */
3511 /* Make the mask to be used against the extracted field. */
3518 /* If not comparing with constant, just rework the comparison
3519 and return. */
3523 unsigned_type,
3526 mask),
3529 unsigned_type,
3532 mask));
3534 /* Otherwise, we are handling the constant case. See if the constant is too
3535 big for the field. Warn and return a tree of for 0 (false) if so. We do
3536 this not only for its own sake, but to avoid having to test for this
3537 error case below. If we didn't, we might generate wrong code.
3539 For unsigned fields, the constant shifted right by the field length should
3540 be all zero. For signed fields, the high-order bits should agree with
3541 the sign bit. */
3544 {
3546 {
3550 }
3551 }
3552 else
3553 {
3556 {
3560 }
3561 }
3563 /* Single-bit compares should always be against zero. */
3565 {
3568 }
3570 /* Make a new bitfield reference, shift the constant over the
3571 appropriate number of bits and mask it with the computed mask
3572 (in case this was a signed field). If we changed it, make a new one. */
3579 mask);
3584 }
3585 \f
3586 /* Subroutine for fold_truth_andor_1: decode a field reference.
3588 If EXP is a comparison reference, we return the innermost reference.
3590 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3591 set to the starting bit number.
3593 If the innermost field can be completely contained in a mode-sized
3594 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3596 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3597 otherwise it is not changed.
3599 *PUNSIGNEDP is set to the signedness of the field.
3601 *PMASK is set to the mask used. This is either contained in a
3602 BIT_AND_EXPR or derived from the width of the field.
3604 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3606 Return 0 if this is not a component reference or is one that we can't
3607 do anything with. */
3609 static tree
3614 {
3618 tree unsigned_type;
3621 /* All the optimizations using this function assume integer fields.
3622 There are problems with FP fields since the type_for_size call
3623 below can fail for, e.g., XFmode. */
3627 /* We are interested in the bare arrangement of bits, so strip everything
3628 that doesn't affect the machine mode. However, record the type of the
3629 outermost expression if it may matter below. */
3636 {
3642 }
3651 /* If the number of bits in the reference is the same as the bitsize of
3652 the outer type, then the outer type gives the signedness. Otherwise
3653 (in case of a small bitfield) the signedness is unchanged. */
3657 /* Compute the mask to access the bitfield. */
3666 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3674 }
3676 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3677 bit positions and MASK is SIGNED. */
3679 static int
3681 {
3685 /* If this function returns true when the type of the mask is
3686 UNSIGNED, then there will be errors. In particular see
3687 gcc.c-torture/execute/990326-1.c. There does not appear to be
3688 any documentation paper trail as to why this is so. But the pre
3689 wide-int worked with that restriction and it has been preserved
3690 here. */
3695 }
3697 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3698 represents the sign bit of EXP's type. If EXP represents a sign
3699 or zero extension, also test VAL against the unextended type.
3700 The return value is the (sub)expression whose sign bit is VAL,
3701 or NULL_TREE otherwise. */
3703 static tree
3705 {
3707 tree t;
3709 /* Tree EXP must have an integral type. */
3714 /* Tree VAL must be an integer constant. */
3723 /* Handle extension from a narrower type. */
3729 }
3731 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3732 to be evaluated unconditionally. */
3734 static int
3736 {
3737 /* Strip any conversions that don't change the machine mode. */
3746 /* Don't regard global variables as simple. They may be
3747 allocated in ways unknown to the compiler (shared memory,
3748 #pragma weak, etc). */
3751 /* Weakrefs are not safe to be read, since they can be NULL.
3752 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3753 have DECL_WEAK flag set. */
3755 /* Loading a static variable is unduly expensive, but global
3756 registers aren't expensive. */
3758 }
3760 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3761 to be evaluated unconditionally.
3762 I addition to simple_operand_p, we assume that comparisons, conversions,
3763 and logic-not operations are simple, if their operands are simple, too. */
3765 static bool
3767 {
3787 }
3789 \f
3790 /* The following functions are subroutines to fold_range_test and allow it to
3791 try to change a logical combination of comparisons into a range test.
3793 For example, both
3794 X == 2 || X == 3 || X == 4 || X == 5
3795 and
3796 X >= 2 && X <= 5
3797 are converted to
3798 (unsigned) (X - 2) <= 3
3800 We describe each set of comparisons as being either inside or outside
3801 a range, using a variable named like IN_P, and then describe the
3802 range with a lower and upper bound. If one of the bounds is omitted,
3803 it represents either the highest or lowest value of the type.
3805 In the comments below, we represent a range by two numbers in brackets
3806 preceded by a "+" to designate being inside that range, or a "-" to
3807 designate being outside that range, so the condition can be inverted by
3808 flipping the prefix. An omitted bound is represented by a "-". For
3809 example, "- [-, 10]" means being outside the range starting at the lowest
3810 possible value and ending at 10, in other words, being greater than 10.
3811 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3812 always false.
3814 We set up things so that the missing bounds are handled in a consistent
3815 manner so neither a missing bound nor "true" and "false" need to be
3816 handled using a special case. */
3818 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3819 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3820 and UPPER1_P are nonzero if the respective argument is an upper bound
3821 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3822 must be specified for a comparison. ARG1 will be converted to ARG0's
3823 type if both are specified. */
3825 static tree
3828 {
3829 tree tem;
3833 /* If neither arg represents infinity, do the normal operation.
3834 Else, if not a comparison, return infinity. Else handle the special
3835 comparison rules. Note that most of the cases below won't occur, but
3836 are handled for consistency. */
3839 {
3844 }
3849 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3850 for neither. In real maths, we cannot assume open ended ranges are
3851 the same. But, this is computer arithmetic, where numbers are finite.
3852 We can therefore make the transformation of any unbounded range with
3853 the value Z, Z being greater than any representable number. This permits
3854 us to treat unbounded ranges as equal. */
3858 {
3879 }
3882 }
3883 \f
3884 /* Helper routine for make_range. Perform one step for it, return
3885 new expression if the loop should continue or NULL_TREE if it should
3886 stop. */
3888 tree
3892 {
3898 {
3900 /* We can only do something if the range is testing for zero. */
3909 /* We can only do something if the range is testing for zero
3910 and if the second operand is an integer constant. Note that
3911 saying something is "in" the range we make is done by
3912 complementing IN_P since it will set in the initial case of
3913 being not equal to zero; "out" is leaving it alone. */
3920 {
3941 }
3943 /* If this is an unsigned comparison, we also know that EXP is
3944 greater than or equal to zero. We base the range tests we make
3945 on that fact, so we record it here so we can parse existing
3946 range tests. We test arg0_type since often the return type
3947 of, e.g. EQ_EXPR, is boolean. */
3949 {
3953 NULL_TREE))
3958 /* If the high bound is missing, but we have a nonzero low
3959 bound, reverse the range so it goes from zero to the low bound
3960 minus 1. */
3962 {
3967 }
3968 }
3976 /* If flag_wrapv and ARG0_TYPE is signed, make sure
3977 low and high are non-NULL, then normalize will DTRT. */
3980 {
3985 }
3987 /* (-x) IN [a,b] -> x in [-b, -a] */
3999 /* ~ X -> -X - 1 */
4008 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4009 move a constant to the other side. */
4014 /* If EXP is signed, any overflow in the computation is undefined,
4015 so we don't worry about it so long as our computations on
4016 the bounds don't overflow. For unsigned, overflow is defined
4017 and this is exactly the right thing. */
4029 normalize:
4030 /* Check for an unsigned range which has wrapped around the maximum
4031 value thus making n_high < n_low, and normalize it. */
4033 {
4039 /* If the range is of the form +/- [ x+1, x ], we won't
4040 be able to normalize it. But then, it represents the
4041 whole range or the empty set, so make it
4042 +/- [ -, - ]. */
4046 else
4048 }
4049 else
4057 CASE_CONVERT:
4075 /* If we're converting arg0 from an unsigned type, to exp,
4076 a signed type, we will be doing the comparison as unsigned.
4077 The tests above have already verified that LOW and HIGH
4078 are both positive.
4080 So we have to ensure that we will handle large unsigned
4081 values the same way that the current signed bounds treat
4082 negative values. */
4085 {
4086 tree high_positive;
4087 tree equiv_type;
4088 /* For fixed-point modes, we need to pass the saturating flag
4089 as the 2nd parameter. */
4091 equiv_type
4094 else
4095 equiv_type
4098 /* A range without an upper bound is, naturally, unbounded.
4099 Since convert would have cropped a very large value, use
4100 the max value for the destination type. */
4101 high_positive
4108 high_positive),
4111 /* If the low bound is specified, "and" the range with the
4112 range for which the original unsigned value will be
4113 positive. */
4115 {
4118 integer_zero_node),
4119 high_positive))
4123 }
4124 else
4125 {
4126 /* Otherwise, "or" the range with the range of the input
4127 that will be interpreted as negative. */
4130 integer_zero_node),
4131 high_positive))
4135 }
4136 }
4145 }
4146 }
4148 /* Given EXP, a logical expression, set the range it is testing into
4149 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4150 actually being tested. *PLOW and *PHIGH will be made of the same
4151 type as the returned expression. If EXP is not a comparison, we
4152 will most likely not be returning a useful value and range. Set
4153 *STRICT_OVERFLOW_P to true if the return value is only valid
4154 because signed overflow is undefined; otherwise, do not change
4155 *STRICT_OVERFLOW_P. */
4157 tree
4160 {
4168 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4169 and see if we can refine the range. Some of the cases below may not
4170 happen, but it doesn't seem worth worrying about this. We "continue"
4171 the outer loop when we've changed something; otherwise we "break"
4172 the switch, which will "break" the while. */
4178 {
4184 {
4192 }
4201 }
4203 /* If EXP is a constant, we can evaluate whether this is true or false. */
4205 {
4212 }
4216 }
4217 \f
4218 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4219 type, TYPE, return an expression to test if EXP is in (or out of, depending
4220 on IN_P) the range. Return 0 if the test couldn't be created. */
4222 tree
4225 {
4228 #ifdef HAVE_canonicalize_funcptr_for_compare
4229 /* Disable this optimization for function pointer expressions
4230 on targets that require function pointer canonicalization. */
4235 #endif
4238 {
4244 }
4262 {
4264 {
4268 }
4270 }
4272 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4274 {
4278 {
4280 {
4283 etype
4285 else
4288 }
4291 }
4292 }
4294 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4295 This requires wrap-around arithmetics for the type of the expression.
4296 First make sure that arithmetics in this type is valid, then make sure
4297 that it wraps around. */
4303 {
4306 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4307 for the type in question, as we rely on this here. */
4317 else
4319 }
4329 {
4331 {
4336 }
4338 }
4346 }
4347 \f
4348 /* Return the predecessor of VAL in its type, handling the infinite case. */
4350 static tree
4352 {
4358 else
4361 }
4363 /* Return the successor of VAL in its type, handling the infinite case. */
4365 static tree
4367 {
4373 else
4376 }
4378 /* Given two ranges, see if we can merge them into one. Return 1 if we
4379 can, 0 if we can't. Set the output range into the specified parameters. */
4381 bool
4384 {
4388 tree tem;
4398 /* Make range 0 be the range that starts first, or ends last if they
4399 start at the same value. Swap them if it isn't. */
4402 || (lowequal
4405 {
4409 }
4411 /* Now flag two cases, whether the ranges are disjoint or whether the
4412 second range is totally subsumed in the first. Note that the tests
4413 below are simplified by the ones above. */
4419 /* We now have four cases, depending on whether we are including or
4420 excluding the two ranges. */
4422 {
4423 /* If they don't overlap, the result is false. If the second range
4424 is a subset it is the result. Otherwise, the range is from the start
4425 of the second to the end of the first. */
4430 else
4432 }
4435 {
4436 /* If they don't overlap, the result is the first range. If they are
4437 equal, the result is false. If the second range is a subset of the
4438 first, and the ranges begin at the same place, we go from just after
4439 the end of the second range to the end of the first. If the second
4440 range is not a subset of the first, or if it is a subset and both
4441 ranges end at the same place, the range starts at the start of the
4442 first range and ends just before the second range.
4443 Otherwise, we can't describe this as a single range. */
4449 {
4454 {
4455 /* We are in the weird situation where high0 > high1 but
4456 high1 has no successor. Punt. */
4458 }
4459 }
4461 {
4466 {
4467 /* low0 < low1 but low1 has no predecessor. Punt. */
4469 }
4470 }
4471 else
4473 }
4476 {
4477 /* If they don't overlap, the result is the second range. If the second
4478 is a subset of the first, the result is false. Otherwise,
4479 the range starts just after the first range and ends at the
4480 end of the second. */
4485 else
4486 {
4491 {
4492 /* high1 > high0 but high0 has no successor. Punt. */
4494 }
4495 }
4496 }
4498 else
4499 {
4500 /* The case where we are excluding both ranges. Here the complex case
4501 is if they don't overlap. In that case, the only time we have a
4502 range is if they are adjacent. If the second is a subset of the
4503 first, the result is the first. Otherwise, the range to exclude
4504 starts at the beginning of the first range and ends at the end of the
4505 second. */
4507 {
4512 else
4513 {
4514 /* Canonicalize - [min, x] into - [-, x]. */
4517 {
4522 /* FALLTHROUGH */
4535 }
4537 /* Canonicalize - [x, max] into - [x, -]. */
4540 {
4545 /* FALLTHROUGH */
4561 }
4563 /* The ranges might be also adjacent between the maximum and
4564 minimum values of the given type. For
4565 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4566 return + [x + 1, y - 1]. */
4568 {
4575 }
4576 else
4578 }
4579 }
4582 else
4584 }
4588 }
4589 \f
4591 /* Subroutine of fold, looking inside expressions of the form
4592 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4593 of the COND_EXPR. This function is being used also to optimize
4594 A op B ? C : A, by reversing the comparison first.
4596 Return a folded expression whose code is not a COND_EXPR
4597 anymore, or NULL_TREE if no folding opportunity is found. */
4599 static tree
4602 {
4607 tree tem;
4612 /* If we have A op 0 ? A : -A, consider applying the following
4613 transformations:
4615 A == 0? A : -A same as -A
4616 A != 0? A : -A same as A
4617 A >= 0? A : -A same as abs (A)
4618 A > 0? A : -A same as abs (A)
4619 A <= 0? A : -A same as -abs (A)
4620 A < 0? A : -A same as -abs (A)
4622 None of these transformations work for modes with signed
4623 zeros. If A is +/-0, the first two transformations will
4624 change the sign of the result (from +0 to -0, or vice
4625 versa). The last four will fix the sign of the result,
4626 even though the original expressions could be positive or
4627 negative, depending on the sign of A.
4629 Note that all these transformations are correct if A is
4630 NaN, since the two alternatives (A and -A) are also NaNs. */
4637 /* In the case that A is of the form X-Y, '-A' (arg2) may
4638 have already been folded to Y-X, check for that. */
4646 {
4660 /* Fall through. */
4682 }
4684 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4685 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4686 both transformations are correct when A is NaN: A != 0
4687 is then true, and A == 0 is false. */
4691 {
4696 }
4698 /* Try some transformations of A op B ? A : B.
4700 A == B? A : B same as B
4701 A != B? A : B same as A
4702 A >= B? A : B same as max (A, B)
4703 A > B? A : B same as max (B, A)
4704 A <= B? A : B same as min (A, B)
4705 A < B? A : B same as min (B, A)
4707 As above, these transformations don't work in the presence
4708 of signed zeros. For example, if A and B are zeros of
4709 opposite sign, the first two transformations will change
4710 the sign of the result. In the last four, the original
4711 expressions give different results for (A=+0, B=-0) and
4712 (A=-0, B=+0), but the transformed expressions do not.
4714 The first two transformations are correct if either A or B
4715 is a NaN. In the first transformation, the condition will
4716 be false, and B will indeed be chosen. In the case of the
4717 second transformation, the condition A != B will be true,
4718 and A will be chosen.
4720 The conversions to max() and min() are not correct if B is
4721 a number and A is not. The conditions in the original
4722 expressions will be false, so all four give B. The min()
4723 and max() versions would give a NaN instead. */
4726 /* Avoid these transformations if the COND_EXPR may be used
4727 as an lvalue in the C++ front-end. PR c++/19199. */
4728 && (in_gimple_form
4734 {
4739 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4741 {
4745 }
4748 {
4757 /* In C++ a ?: expression can be an lvalue, so put the
4758 operand which will be used if they are equal first
4759 so that we can convert this back to the
4760 corresponding COND_EXPR. */
4762 {
4771 }
4778 {
4787 }
4802 }
4803 }
4805 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4806 we might still be able to simplify this. For example,
4807 if C1 is one less or one more than C2, this might have started
4808 out as a MIN or MAX and been transformed by this function.
4809 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4815 {
4819 /* We can replace A with C1 in this case. */
4824 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
4825 MIN_EXPR, to preserve the signedness of the comparison. */
4827 OEP_ONLY_CONST)
4831 OEP_ONLY_CONST))
4832 {
4835 arg2));
4838 }
4842 /* If C1 is C2 - 1, this is min(A, C2), with the same care
4843 as above. */
4845 OEP_ONLY_CONST)
4849 OEP_ONLY_CONST))
4850 {
4853 arg2));
4856 }
4860 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
4861 MAX_EXPR, to preserve the signedness of the comparison. */
4863 OEP_ONLY_CONST)
4867 OEP_ONLY_CONST))
4868 {
4871 arg2));
4873 }
4877 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
4879 OEP_ONLY_CONST)
4883 OEP_ONLY_CONST))
4884 {
4887 arg2));
4889 }
4895 }
4898 }
4901 \f
4902 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4903 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
4904 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
4905 false) >= 2)
4906 #endif
4908 /* EXP is some logical combination of boolean tests. See if we can
4909 merge it into some range test. Return the new tree if so. */
4911 static tree
4914 {
4930 /* If this is an OR operation, invert both sides; we will invert
4931 again at the end. */
4935 /* If both expressions are the same, if we can merge the ranges, and we
4936 can build the range test, return it or it inverted. If one of the
4937 ranges is always true or always false, consider it to be the same
4938 expression as the other. */
4946 {
4950 }
4952 /* On machines where the branch cost is expensive, if this is a
4953 short-circuited branch and the underlying object on both sides
4954 is the same, make a non-short-circuit operation. */
4960 {
4961 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4962 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4963 which cases we can't do this. */
4971 {
4980 {
4983 WARN_STRICT_OVERFLOW_COMPARISON);
4987 }
4988 }
4989 }
4992 }
4993 \f
4994 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
4995 bit value. Arrange things so the extra bits will be set to zero if and
4996 only if C is signed-extended to its full width. If MASK is nonzero,
4997 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4999 static tree
5001 {
5004 tree temp;
5009 /* We work by getting just the sign bit into the low-order bit, then
5010 into the high-order bit, then sign-extend. We then XOR that value
5011 with C. */
5014 /* We must use a signed type in order to get an arithmetic right shift.
5015 However, we must also avoid introducing accidental overflows, so that
5016 a subsequent call to integer_zerop will work. Hence we must
5017 do the type conversion here. At this point, the constant is either
5018 zero or one, and the conversion to a signed type can never overflow.
5019 We could get an overflow if this conversion is done anywhere else. */
5028 /* If necessary, convert the type back to match the type of C. */
5033 }
5034 \f
5035 /* For an expression that has the form
5036 (A && B) || ~B
5037 or
5038 (A || B) && ~B,
5039 we can drop one of the inner expressions and simplify to
5040 A || ~B
5041 or
5042 A && ~B
5043 LOC is the location of the resulting expression. OP is the inner
5044 logical operation; the left-hand side in the examples above, while CMPOP
5045 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5046 removing a condition that guards another, as in
5047 (A != NULL && A->...) || A == NULL
5048 which we must not transform. If RHS_ONLY is true, only eliminate the
5049 right-most operand of the inner logical operation. */
5051 static tree
5054 {
5072 {
5075 {
5078 }
5079 }
5081 {
5084 {
5087 }
5088 }
5103 }
5105 /* Find ways of folding logical expressions of LHS and RHS:
5106 Try to merge two comparisons to the same innermost item.
5107 Look for range tests like "ch >= '0' && ch <= '9'".
5108 Look for combinations of simple terms on machines with expensive branches
5109 and evaluate the RHS unconditionally.
5111 For example, if we have p->a == 2 && p->b == 4 and we can make an
5112 object large enough to span both A and B, we can do this with a comparison
5113 against the object ANDed with the a mask.
5115 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5116 operations to do this with one comparison.
5118 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5119 function and the one above.
5121 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5122 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5124 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5125 two operands.
5127 We return the simplified tree or 0 if no optimization is possible. */
5129 static tree
5132 {
5133 /* If this is the "or" of two comparisons, we can do something if
5134 the comparisons are NE_EXPR. If this is the "and", we can do something
5135 if the comparisons are EQ_EXPR. I.e.,
5136 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5138 WANTED_CODE is this operation code. For single bit fields, we can
5139 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5140 comparison for one-bit fields. */
5160 /* Start by getting the comparison codes. Fail if anything is volatile.
5161 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5162 it were surrounded with a NE_EXPR. */
5171 {
5175 }
5178 {
5182 }
5193 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5196 {
5199 {
5204 }
5207 {
5213 }
5214 }
5219 /* If the RHS can be evaluated unconditionally and its operands are
5220 simple, it wins to evaluate the RHS unconditionally on machines
5221 with expensive branches. In this case, this isn't a comparison
5222 that can be merged. */
5229 {
5230 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5241 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5251 }
5253 /* See if the comparisons can be merged. Then get all the parameters for
5254 each side. */
5278 /* It must be true that the inner operation on the lhs of each
5279 comparison must be the same if we are to be able to do anything.
5280 Then see if we have constants. If not, the same must be true for
5281 the rhs's. */
5292 else
5295 /* If either comparison code is not correct for our logical operation,
5296 fail. However, we can convert a one-bit comparison against zero into
5297 the opposite comparison against that bit being set in the field. */
5301 {
5303 {
5304 /* Make the left operand unsigned, since we are only interested
5305 in the value of one bit. Otherwise we are doing the wrong
5306 thing below. */
5309 }
5310 else
5312 }
5314 /* This is analogous to the code for l_const above. */
5316 {
5318 {
5321 }
5322 else
5324 }
5326 /* See if we can find a mode that contains both fields being compared on
5327 the left. If we can't, fail. Otherwise, update all constants and masks
5328 to be relative to a field of that size. */
5333 volatilep);
5343 {
5346 }
5354 {
5361 {
5365 }
5366 }
5368 {
5375 {
5379 }
5380 }
5382 /* If the right sides are not constant, do the same for it. Also,
5383 disallow this optimization if a size or signedness mismatch occurs
5384 between the left and right sides. */
5386 {
5389 /* Make sure the two fields on the right
5390 correspond to the left without being swapped. */
5398 volatilep);
5408 {
5411 }
5420 /* Make a mask that corresponds to both fields being compared.
5421 Do this for both items being compared. If the operands are the
5422 same size and the bits being compared are in the same position
5423 then we can do this by masking both and comparing the masked
5424 results. */
5428 {
5440 }
5442 /* There is still another way we can do something: If both pairs of
5443 fields being compared are adjacent, we may be able to make a wider
5444 field containing them both.
5446 Note that we still must mask the lhs/rhs expressions. Furthermore,
5447 the mask must be shifted to account for the shift done by
5448 make_bit_field_ref. */
5453 {
5454 tree type;
5468 /* Convert to the smaller type before masking out unwanted bits. */
5471 {
5473 {
5477 }
5479 {
5483 }
5484 }
5493 }
5496 }
5498 /* Handle the case of comparisons with constants. If there is something in
5499 common between the masks, those bits of the constants must be the same.
5500 If not, the condition is always false. Test for this to avoid generating
5501 incorrect code below. */
5506 {
5508 {
5511 }
5512 else
5513 {
5516 }
5517 }
5519 /* Construct the expression we will return. First get the component
5520 reference we will make. Unless the mask is all ones the width of
5521 that field, perform the mask operation. Then compare with the
5522 merged constant. */
5532 }
5533 \f
5534 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5535 constant. */
5537 static tree
5540 {
5543 tree comp_const;
5544 tree minmax_const;
5546 tree inner;
5557 /* If something does not permit us to optimize, return the original tree. */
5565 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5566 and GT_EXPR, doing the rest with recursive calls using logical
5567 simplifications. */
5569 {
5571 {
5572 tree tem
5579 }
5582 return
5584 optimize_minmax_comparison
5586 optimize_minmax_comparison
5591 /* MAX (X, 0) == 0 -> X <= 0 */
5595 /* MAX (X, 0) == 5 -> X == 5 */
5599 /* MAX (X, 0) == -1 -> false */
5603 /* MIN (X, 0) == 0 -> X >= 0 */
5607 /* MIN (X, 0) == 5 -> false */
5610 else
5611 /* MIN (X, 0) == -1 -> X == -1 */
5616 /* MAX (X, 0) > 0 -> X > 0
5617 MAX (X, 0) > 5 -> X > 5 */
5621 /* MAX (X, 0) > -1 -> true */
5625 /* MIN (X, 0) > 0 -> false
5626 MIN (X, 0) > 5 -> false */
5629 else
5630 /* MIN (X, 0) > -1 -> X > -1 */
5635 }
5636 }
5637 \f
5638 /* T is an integer expression that is being multiplied, divided, or taken a
5639 modulus (CODE says which and what kind of divide or modulus) by a
5640 constant C. See if we can eliminate that operation by folding it with
5641 other operations already in T. WIDE_TYPE, if non-null, is a type that
5642 should be used for the computation if wider than our type.
5644 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5645 (X * 2) + (Y * 4). We must, however, be assured that either the original
5646 expression would not overflow or that overflow is undefined for the type
5647 in the language in question.
5649 If we return a non-null expression, it is an equivalent form of the
5650 original computation, but need not be in the original type.
5652 We set *STRICT_OVERFLOW_P to true if the return values depends on
5653 signed overflow being undefined. Otherwise we do not change
5654 *STRICT_OVERFLOW_P. */
5656 static tree
5659 {
5660 /* To avoid exponential search depth, refuse to allow recursion past
5661 three levels. Beyond that (1) it's highly unlikely that we'll find
5662 something interesting and (2) we've probably processed it before
5663 when we built the inner expression. */
5666 tree ret;
5671 depth++;
5673 depth--;
5676 }
5678 static tree
5681 {
5692 /* Don't deal with constants of zero here; they confuse the code below. */
5702 /* Note that we need not handle conditional operations here since fold
5703 already handles those cases. So just do arithmetic here. */
5705 {
5707 /* For a constant, we can always simplify if we are a multiply
5708 or (for divide and modulus) if it is a multiple of our constant. */
5716 /* If op0 is an expression ... */
5722 /* ... and has wrapping overflow, and its type is smaller
5723 than ctype, then we cannot pass through as widening. */
5727 /* ... or this is a truncation (t is narrower than op0),
5728 then we cannot pass through this narrowing. */
5731 /* ... or signedness changes for division or modulus,
5732 then we cannot pass through this conversion. */
5736 /* ... or has undefined overflow while the converted to
5737 type has not, we cannot do the operation in the inner type
5738 as that would introduce undefined overflow. */
5743 /* Pass the constant down and see if we can make a simplification. If
5744 we can, replace this expression with the inner simplification for
5745 possible later conversion to our or some other type. */
5750 code == MULT_EXPR
5752 strict_overflow_p))))
5757 /* If widening the type changes it from signed to unsigned, then we
5758 must avoid building ABS_EXPR itself as unsigned. */
5760 {
5764 {
5767 }
5769 }
5770 /* If the constant is negative, we cannot simplify this. */
5773 /* FALLTHROUGH */
5775 /* For division and modulus, type can't be unsigned, as e.g.
5776 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
5777 For signed types, even with wrapping overflow, this is fine. */
5786 /* If widening the type changes the signedness, then we can't perform
5787 this optimization as that changes the result. */
5791 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5797 {
5804 }
5808 /* If the second operand is constant, this is a multiplication
5809 or floor division, by a power of two, so we can treat it that
5810 way unless the multiplier or divisor overflows. Signed
5811 left-shift overflow is implementation-defined rather than
5812 undefined in C90, so do not convert signed left shift into
5813 multiplication. */
5816 /* const_binop may not detect overflow correctly,
5817 so check for it explicitly here. */
5821 size_one_node,
5822 op1)))
5826 ctype,
5828 t1),
5833 /* See if we can eliminate the operation on both sides. If we can, we
5834 can return a new PLUS or MINUS. If we can't, the only remaining
5835 cases where we can do anything are if the second operand is a
5836 constant. */
5842 /* If not multiplication, we can only do this if both operands
5843 are divisible by c. */
5846 {
5851 }
5853 /* If this was a subtraction, negate OP1 and set it to be an addition.
5854 This simplifies the logic below. */
5856 {
5858 /* If OP1 was not easily negatable, the constant may be OP0. */
5860 {
5867 }
5868 }
5873 /* If either OP1 or C are negative, this optimization is not safe for
5874 some of the division and remainder types while for others we need
5875 to change the code. */
5877 {
5885 }
5887 /* If it's a multiply or a division/modulus operation of a multiple
5888 of our constant, do the operation and verify it doesn't overflow. */
5891 {
5894 /* We allow the constant to overflow with wrapping semantics. */
5898 }
5899 else
5902 /* If we have an unsigned type, we cannot widen the operation since it
5903 will change the result if the original computation overflowed. */
5907 /* If we were able to eliminate our operation from the first side,
5908 apply our operation to the second side and reform the PLUS. */
5912 /* The last case is if we are a multiply. In that case, we can
5913 apply the distributive law to commute the multiply and addition
5914 if the multiplication of the constants doesn't overflow
5915 and overflow is defined. With undefined overflow
5916 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
5922 op1);
5927 /* We have a special case here if we are doing something like
5928 (C * 8) % 4 since we know that's zero. */
5931 /* If the multiplication can overflow we cannot optimize this. */
5935 {
5938 }
5940 /* ... fall through ... */
5944 /* If we can extract our operation from the LHS, do so and return a
5945 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5946 do something only if the second operand is a constant. */
5960 /* If these are the same operation types, we can associate them
5961 assuming no overflow. */
5963 {
5975 }
5977 /* If these operations "cancel" each other, we have the main
5978 optimizations of this pass, which occur when either constant is a
5979 multiple of the other, in which case we replace this with either an
5980 operation or CODE or TCODE.
5982 If we have an unsigned type, we cannot do this since it will change
5983 the result if the original computation overflowed. */
5990 {
5992 {
5999 }
6001 {
6008 }
6009 }
6014 }
6017 }
6018 \f
6019 /* Return a node which has the indicated constant VALUE (either 0 or
6020 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6021 and is of the indicated TYPE. */
6023 tree
6025 {
6034 else
6036 }
6039 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6040 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6041 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6042 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6043 COND is the first argument to CODE; otherwise (as in the example
6044 given here), it is the second argument. TYPE is the type of the
6045 original expression. Return NULL_TREE if no simplification is
6046 possible. */
6048 static tree
6053 {
6063 {
6067 /* If this operand throws an expression, then it does not make
6068 sense to try to perform a logical or arithmetic operation
6069 involving it. */
6074 }
6075 else
6076 {
6081 }
6086 /* This transformation is only worthwhile if we don't have to wrap ARG
6087 in a SAVE_EXPR and the operation can be simplified without recursing
6088 on at least one of the branches once its pushed inside the COND_EXPR. */
6097 {
6101 else
6103 }
6105 {
6109 else
6111 }
6113 /* Check that we have simplified at least one of the branches. */
6118 }
6120 \f
6121 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6123 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6124 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6125 ADDEND is the same as X.
6127 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6128 and finite. The problematic cases are when X is zero, and its mode
6129 has signed zeros. In the case of rounding towards -infinity,
6130 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6131 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6133 bool
6135 {
6139 /* Don't allow the fold with -fsignaling-nans. */
6143 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6147 /* In a vector or complex, we would need to check the sign of all zeros. */
6151 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6155 /* The mode has signed zeros, and we have to honor their sign.
6156 In this situation, there is only one case we can return true for.
6157 X - 0 is the same as X unless rounding towards -infinity is
6158 supported. */
6160 }
6162 /* Subroutine of fold() that checks comparisons of built-in math
6163 functions against real constants.
6165 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6166 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6167 is the type of the result and ARG0 and ARG1 are the operands of the
6168 comparison. ARG1 must be a TREE_REAL_CST.
6170 The function returns the constant folded tree if a simplification
6171 can be made, and NULL_TREE otherwise. */
6173 static tree
6177 {
6178 REAL_VALUE_TYPE c;
6181 {
6187 {
6188 /* sqrt(x) < y is always false, if y is negative. */
6192 /* sqrt(x) > y is always true, if y is negative and we
6193 don't care about NaNs, i.e. negative values of x. */
6197 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6200 }
6202 {
6203 REAL_VALUE_TYPE c2;
6209 {
6210 /* sqrt(x) > y is x == +Inf, when y is very large. */
6215 /* sqrt(x) > y is always false, when y is very large
6216 and we don't care about infinities. */
6218 }
6220 /* sqrt(x) > c is the same as x > c*c. */
6223 }
6225 {
6226 REAL_VALUE_TYPE c2;
6232 {
6233 /* sqrt(x) < y is always true, when y is a very large
6234 value and we don't care about NaNs or Infinities. */
6238 /* sqrt(x) < y is x != +Inf when y is very large and we
6239 don't care about NaNs. */
6244 /* sqrt(x) < y is x >= 0 when y is very large and we
6245 don't care about Infinities. */
6250 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6255 dconst0)),
6258 c2)));
6259 }
6261 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6266 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6271 dconst0)),
6274 c2)));
6275 }
6276 }
6279 }
6281 /* Subroutine of fold() that optimizes comparisons against Infinities,
6282 either +Inf or -Inf.
6284 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6285 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6286 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6288 The function returns the constant folded tree if a simplification
6289 can be made, and NULL_TREE otherwise. */
6291 static tree
6294 {
6295 machine_mode mode;
6296 REAL_VALUE_TYPE max;
6297 tree temp;
6302 /* For negative infinity swap the sense of the comparison. */
6308 {
6310 /* x > +Inf is always false, if with ignore sNANs. */
6316 /* x <= +Inf is always true, if we don't case about NaNs. */
6320 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6326 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6332 /* x < +Inf is always equal to x <= DBL_MAX. */
6338 /* x != +Inf is always equal to !(x > DBL_MAX). */
6350 }
6353 }
6355 /* Subroutine of fold() that optimizes comparisons of a division by
6356 a nonzero integer constant against an integer constant, i.e.
6357 X/C1 op C2.
6359 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6360 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6361 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6363 The function returns the constant folded tree if a simplification
6364 can be made, and NULL_TREE otherwise. */
6366 static tree
6369 {
6377 /* We have to do this the hard way to detect unsigned overflow.
6378 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6384 {
6389 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6393 }
6395 {
6399 {
6418 }
6419 }
6420 else
6421 {
6422 /* A negative divisor reverses the relational operators. */
6428 {
6447 }
6448 }
6451 {
6472 {
6475 }
6480 {
6483 }
6488 {
6491 }
6496 {
6499 }
6504 }
6507 }
6510 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6511 equality/inequality test, then return a simplified form of the test
6512 using a sign testing. Otherwise return NULL. TYPE is the desired
6513 result type. */
6515 static tree
6518 tree result_type)
6519 {
6520 /* If this is testing a single bit, we can optimize the test. */
6524 {
6525 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6526 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6530 /* This is only a win if casting to a signed type is cheap,
6531 i.e. when arg00's type is not a partial mode. */
6534 {
6537 result_type,
6540 }
6541 }
6544 }
6546 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6547 equality/inequality test, then return a simplified form of
6548 the test using shifts and logical operations. Otherwise return
6549 NULL. TYPE is the desired result type. */
6551 tree
6554 {
6555 /* If this is testing a single bit, we can optimize the test. */
6559 {
6568 /* First, see if we can fold the single bit test into a sign-bit
6569 test. */
6571 result_type);
6575 /* Otherwise we have (A & C) != 0 where C is a single bit,
6576 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6577 Similarly for (A & C) == 0. */
6579 /* If INNER is a right shift of a constant and it plus BITNUM does
6580 not overflow, adjust BITNUM and INNER. */
6586 {
6589 }
6591 /* If we are going to be able to omit the AND below, we must do our
6592 operations as unsigned. If we must use the AND, we have a choice.
6593 Normally unsigned is faster, but for some machines signed is. */
6594 #ifdef LOAD_EXTEND_OP
6597 #else
6599 #endif
6615 /* Put the AND last so it can combine with more things. */
6618 /* Make sure to return the proper type. */
6622 }
6624 }
6626 /* Check whether we are allowed to reorder operands arg0 and arg1,
6627 such that the evaluation of arg1 occurs before arg0. */
6629 static bool
6631 {
6638 }
6640 /* Test whether it is preferable two swap two operands, ARG0 and
6641 ARG1, for example because ARG0 is an integer constant and ARG1
6642 isn't. If REORDER is true, only recommend swapping if we can
6643 evaluate the operands in reverse order. */
6645 bool
6647 {
6665 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6666 for commutative and comparison operators. Ensuring a canonical
6667 form allows the optimizers to find additional redundancies without
6668 having to explicitly check for both orderings. */
6674 /* Put SSA_NAMEs last. */
6680 /* Put variables last. */
6687 }
6689 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6690 ARG0 is extended to a wider type. */
6692 static tree
6695 {
6697 tree arg1_unw;
6706 #ifdef HAVE_canonicalize_funcptr_for_compare
6707 /* Disable this optimization if we're casting a function pointer
6708 type on targets that require function pointer canonicalization. */
6713 #endif
6720 /* If possible, express the comparison in the shorter mode. */
6740 /* If we are comparing with the integer that does not fit into the range
6741 of the shorter type, the result is known. */
6752 {
6779 }
6782 }
6784 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6785 ARG0 just the signedness is changed. */
6787 static tree
6790 {
6791 tree arg0_inner;
6801 #ifdef HAVE_canonicalize_funcptr_for_compare
6802 /* Disable this optimization if we're casting a function pointer
6803 type on targets that require function pointer canonicalization. */
6808 #endif
6829 else
6833 }
6836 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6837 means A >= Y && A != MAX, but in this case we know that
6838 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6840 static tree
6842 {
6849 else
6858 {
6861 }
6863 {
6866 }
6867 else
6874 {
6875 /* Convert the pointer types into integer before taking the difference. */
6879 }
6880 else
6887 }
6889 /* Fold a sum or difference of at least one multiplication.
6890 Returns the folded tree or NULL if no simplification could be made. */
6892 static tree
6895 {
6899 /* (A * C) +- (B * C) -> (A+-B) * C.
6900 (A * C) +- A -> A * (C+-1).
6901 We are most concerned about the case where C is a constant,
6902 but other combinations show up during loop reduction. Since
6903 it is not difficult, try all four possibilities. */
6906 {
6909 }
6911 {
6914 }
6915 else
6916 {
6917 /* We cannot generate constant 1 for fract. */
6922 }
6924 {
6927 }
6929 {
6931 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6932 the purpose of this canonicalization. */
6936 {
6939 }
6940 else
6942 }
6943 else
6944 {
6945 /* We cannot generate constant 1 for fract. */
6950 }
6962 /* No identical multiplicands; see if we can find a common
6963 power-of-two factor in non-power-of-two multiplies. This
6964 can help in multi-dimensional array access. */
6967 {
6970 tree maybe_same;
6974 /* Move min of absolute values to int11. */
6976 {
6981 }
6982 else
6986 /* The remainder should not be a constant, otherwise we
6987 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6988 increased the number of multiplications necessary. */
6990 {
6998 }
6999 }
7009 }
7011 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7012 specified by EXPR into the buffer PTR of length LEN bytes.
7013 Return the number of bytes placed in the buffer, or zero
7014 upon failure. */
7016 static int
7018 {
7032 {
7034 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7035 number of bytes. */
7039 {
7046 else
7048 }
7049 else
7054 }
7056 }
7059 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7060 specified by EXPR into the buffer PTR of length LEN bytes.
7061 Return the number of bytes placed in the buffer, or zero
7062 upon failure. */
7064 static int
7066 {
7070 FIXED_VALUE_TYPE value;
7086 }
7089 /* Subroutine of native_encode_expr. Encode the REAL_CST
7090 specified by EXPR into the buffer PTR of length LEN bytes.
7091 Return the number of bytes placed in the buffer, or zero
7092 upon failure. */
7094 static int
7096 {
7102 /* There are always 32 bits in each long, no matter the size of
7103 the hosts long. We handle floating point representations with
7104 up to 192 bits. */
7118 {
7123 {
7130 else
7132 }
7133 else
7139 }
7141 }
7143 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7144 specified by EXPR into the buffer PTR of length LEN bytes.
7145 Return the number of bytes placed in the buffer, or zero
7146 upon failure. */
7148 static int
7150 {
7152 tree part;
7167 }
7170 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7171 specified by EXPR into the buffer PTR of length LEN bytes.
7172 Return the number of bytes placed in the buffer, or zero
7173 upon failure. */
7175 static int
7177 {
7187 {
7189 {
7192 }
7203 }
7205 }
7208 /* Subroutine of native_encode_expr. Encode the STRING_CST
7209 specified by EXPR into the buffer PTR of length LEN bytes.
7210 Return the number of bytes placed in the buffer, or zero
7211 upon failure. */
7213 static int
7215 {
7217 HOST_WIDE_INT total_bytes;
7231 {
7234 {
7237 }
7240 }
7241 else
7244 }
7247 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7248 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7249 buffer PTR of length LEN bytes. If OFF is not -1 then start
7250 the encoding at byte offset OFF and encode at most LEN bytes.
7251 Return the number of bytes placed in the buffer, or zero upon failure. */
7253 int
7255 {
7257 {
7278 }
7279 }
7282 /* Subroutine of native_interpret_expr. Interpret the contents of
7283 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7284 If the buffer cannot be interpreted, return NULL_TREE. */
7286 static tree
7288 {
7298 }
7301 /* Subroutine of native_interpret_expr. Interpret the contents of
7302 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7303 If the buffer cannot be interpreted, return NULL_TREE. */
7305 static tree
7307 {
7309 double_int result;
7310 FIXED_VALUE_TYPE fixed_value;
7320 }
7323 /* Subroutine of native_interpret_expr. Interpret the contents of
7324 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7325 If the buffer cannot be interpreted, return NULL_TREE. */
7327 static tree
7329 {
7334 /* There are always 32 bits in each long, no matter the size of
7335 the hosts long. We handle floating point representations with
7336 up to 192 bits. */
7337 REAL_VALUE_TYPE r;
7348 {
7351 {
7358 else
7360 }
7361 else
7366 }
7370 }
7373 /* Subroutine of native_interpret_expr. Interpret the contents of
7374 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7375 If the buffer cannot be interpreted, return NULL_TREE. */
7377 static tree
7379 {
7394 }
7397 /* Subroutine of native_interpret_expr. Interpret the contents of
7398 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7399 If the buffer cannot be interpreted, return NULL_TREE. */
7401 static tree
7403 {
7416 {
7421 }
7423 }
7426 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7427 the buffer PTR of length LEN as a constant of type TYPE. For
7428 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7429 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7430 return NULL_TREE. */
7432 tree
7434 {
7436 {
7458 }
7459 }
7461 /* Returns true if we can interpret the contents of a native encoding
7462 as TYPE. */
7464 static bool
7466 {
7468 {
7481 }
7482 }
7484 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7485 TYPE at compile-time. If we're unable to perform the conversion
7486 return NULL_TREE. */
7488 static tree
7490 {
7491 /* We support up to 512-bit values (for V8DFmode). */
7495 /* Check that the host and target are sane. */
7504 }
7506 /* Build an expression for the address of T. Folds away INDIRECT_REF
7507 to avoid confusing the gimplify process. */
7509 tree
7511 {
7512 /* The size of the object is not relevant when talking about its address. */
7517 {
7522 }
7532 {
7537 }
7538 else
7542 }
7544 /* Build an expression for the address of T. */
7546 tree
7548 {
7552 }
7556 /* Fold a unary expression of code CODE and type TYPE with operand
7557 OP0. Return the folded expression if folding is successful.
7558 Otherwise, return NULL_TREE. */
7560 tree
7562 {
7563 tree tem;
7564 tree arg0;
7576 {
7579 {
7580 /* Don't use STRIP_NOPS, because signedness of argument type
7581 matters. */
7583 }
7584 else
7585 {
7586 /* Strip any conversions that don't change the mode. This
7587 is safe for every expression, except for a comparison
7588 expression because its signedness is derived from its
7589 operands.
7591 Note that this is done as an internal manipulation within
7592 the constant folder, in order to find the simplest
7593 representation of the arguments so that their form can be
7594 studied. In any cases, the appropriate type conversions
7595 should be put back in the tree that will get out of the
7596 constant folder. */
7598 }
7599 }
7602 {
7609 {
7623 /* If this was a conversion, and all we did was to move into
7624 inside the COND_EXPR, bring it back out. But leave it if
7625 it is a conversion from integer to integer and the
7626 result precision is no wider than a word since such a
7627 conversion is cheap and may be optimized away by combine,
7628 while it couldn't if it were outside the COND_EXPR. Then return
7629 so we don't get into an infinite recursion loop taking the
7630 conversion out and then back in. */
7642 && (INTEGRAL_TYPE_P
7655 }
7656 }
7659 {
7665 CASE_CONVERT:
7669 {
7670 /* If we have (type) (a CMP b) and type is an integral type, return
7671 new expression involving the new type. Canonicalize
7672 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7673 non-integral type.
7674 Do not fold the result as that would not simplify further, also
7675 folding again results in recursions. */
7685 }
7687 /* Handle (T *)&A.B.C for A being of type T and B and C
7688 living at offset zero. This occurs frequently in
7689 C++ upcasting and then accessing the base. */
7693 {
7695 tree offset;
7696 machine_mode mode;
7701 /* If the reference was to a (constant) zero offset, we can use
7702 the address of the base if it has the same base type
7703 as the result type and the pointer type is unqualified. */
7710 }
7714 /* Detect assigning a bitfield. */
7716 && DECL_BIT_FIELD
7718 {
7719 /* Don't leave an assignment inside a conversion
7720 unless assigning a bitfield. */
7722 /* First do the assignment, then return converted constant. */
7727 }
7729 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7730 constants (if x has signed type, the sign bit cannot be set
7731 in c). This folds extension into the BIT_AND_EXPR.
7732 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7733 very likely don't have maximal range for their precision and this
7734 transformation effectively doesn't preserve non-maximal ranges. */
7738 {
7749 <= HOST_BITS_PER_WIDE_INT
7751 {
7755 cst &= HOST_WIDE_INT_M1U
7758 #ifdef LOAD_EXTEND_OP
7760 && !flag_syntax_only
7763 {
7767 }
7768 #endif
7769 }
7771 {
7776 }
7777 }
7779 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7780 when one of the new casts will fold away. Conservatively we assume
7781 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7788 {
7792 return fold_build_pointer_plus_loc
7794 }
7796 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7797 of the same precision, and X is an integer type not narrower than
7798 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7804 {
7810 }
7812 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7813 type of X and Y (integer types only). */
7818 {
7819 /* Be careful not to introduce new overflows. */
7820 tree mult_type;
7823 else
7827 {
7834 }
7835 }
7865 /* Convert fabs((double)float) into (double)fabsf(float). */
7868 {
7874 targ0));
7875 }
7876 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7880 /* Strip sign ops from argument. */
7882 {
7887 }
7894 {
7900 }
7902 {
7907 }
7915 /* Convert ~ (-A) to A - 1. */
7920 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7929 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7944 /* Perform BIT_NOT_EXPR on each element individually. */
7946 {
7948 tree elem;
7953 {
7959 }
7962 }
7966 {
7973 }
7979 /* Note that the operand of this must be an int
7980 and its values must be 0 or 1.
7981 ("true" is a fixed value perhaps depending on the language,
7982 but we don't handle values other than 1 correctly yet.) */
7997 {
8005 }
8007 {
8012 }
8014 {
8018 {
8027 }
8028 }
8040 {
8048 }
8050 {
8054 }
8056 {
8060 {
8069 }
8070 }
8074 /* Fold *&X to X if X is an lvalue. */
8076 {
8083 }
8090 {
8109 else
8113 {
8117 }
8120 }
8125 {
8139 {
8144 }
8147 {
8151 }
8154 }
8159 }
8162 /* If the operation was a conversion do _not_ mark a resulting constant
8163 with TREE_OVERFLOW if the original constant was not. These conversions
8164 have implementation defined behavior and retaining the TREE_OVERFLOW
8165 flag here would confuse later passes such as VRP. */
8166 tree
8169 {
8178 }
8180 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8181 operands OP0 and OP1. LOC is the location of the resulting expression.
8182 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8183 Return the folded expression if folding is successful. Otherwise,
8184 return NULL_TREE. */
8185 static tree
8188 {
8189 tree tem;
8191 /* We only do these simplifications if we are optimizing. */
8195 /* Check for things like (A || B) && (A || C). We can convert this
8196 to A || (B && C). Note that either operator can be any of the four
8197 truth and/or operations and the transformation will still be
8198 valid. Also note that we only care about order for the
8199 ANDIF and ORIF operators. If B contains side effects, this
8200 might change the truth-value of A. */
8207 {
8227 /* This case if tricky because we must either have commutative
8228 operators or else A10 must not have side-effects. */
8234 a01);
8235 }
8237 /* See if we can build a range comparison. */
8243 {
8247 }
8251 {
8255 }
8257 /* Check for the possibility of merging component references. If our
8258 lhs is another similar operation, try to merge its rhs with our
8259 rhs. Then try to merge our lhs and rhs. */
8273 {
8280 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8281 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8282 We don't want to pack more than two leafs to a non-IF AND/OR
8283 expression.
8284 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8285 equal to IF-CODE, then we don't want to add right-hand operand.
8286 If the inner right-hand side of left-hand operand has
8287 side-effects, or isn't simple, then we can't add to it,
8288 as otherwise we might destroy if-sequence. */
8291 /* Needed for sequence points to handle trappings, and
8292 side-effects. */
8294 {
8296 arg1);
8298 tem);
8299 }
8300 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8301 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8304 /* Needed for sequence points to handle trappings, and
8305 side-effects. */
8307 {
8312 }
8313 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8314 into (A OR B).
8315 For sequence point consistancy, we need to check for trapping,
8316 and side-effects. */
8320 }
8323 }
8325 /* Fold a binary expression of code CODE and type TYPE with operands
8326 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8327 Return the folded expression if folding is successful. Otherwise,
8328 return NULL_TREE. */
8330 static tree
8332 {
8339 else
8342 /* MIN (MAX (a, b), b) == b. */
8347 /* MIN (MAX (b, a), b) == b. */
8353 /* MIN (a, MAX (a, b)) == a. */
8359 /* MIN (a, MAX (b, a)) == a. */
8366 }
8368 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8369 by changing CODE to reduce the magnitude of constants involved in
8370 ARG0 of the comparison.
8371 Returns a canonicalized comparison tree if a simplification was
8372 possible, otherwise returns NULL_TREE.
8373 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8374 valid if signed overflow is undefined. */
8376 static tree
8380 {
8386 /* Match A +- CST code arg1 and CST code arg1. We can change the
8387 first form only if overflow is undefined. */
8389 /* In principle pointers also have undefined overflow behavior,
8390 but that causes problems elsewhere. */
8398 /* Identify the constant in arg0 and its sign. */
8401 else
8405 /* Overflowed constants and zero will cause problems. */
8410 /* See if we can reduce the magnitude of the constant in
8411 arg0 by changing the comparison code. */
8413 {
8414 /* CST <= arg1 -> CST-1 < arg1. */
8417 /* -CST < arg1 -> -CST-1 <= arg1. */
8420 /* CST > arg1 -> CST-1 >= arg1. */
8423 /* -CST >= arg1 -> -CST-1 > arg1. */
8426 else
8428 /* arg1 code' CST' might be more canonical. */
8430 }
8431 else
8432 {
8433 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8437 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8441 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8445 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8449 else
8452 }
8454 /* Now build the constant reduced in magnitude. But not if that
8455 would produce one outside of its types range. */
8463 /* We cannot swap the comparison here as that would cause us to
8464 endlessly recurse. */
8473 /* If swapping might yield to a more canonical form, do so. */
8476 else
8478 }
8480 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8481 overflow further. Try to decrease the magnitude of constants involved
8482 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8483 and put sole constants at the second argument position.
8484 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8486 static tree
8489 {
8490 tree t;
8495 /* Try canonicalization by simplifying arg0. */
8500 {
8504 }
8506 /* Try canonicalization by simplifying arg1 using the swapped
8507 comparison. */
8515 }
8517 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8518 space. This is used to avoid issuing overflow warnings for
8519 expressions like &p->x which can not wrap. */
8521 static bool
8523 {
8530 wide_int wi_offset;
8536 else
8552 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8553 array. */
8555 {
8556 HOST_WIDE_INT base_size;
8561 }
8564 }
8566 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8567 kind INTEGER_CST. This makes sure to properly sign-extend the
8568 constant. */
8570 static HOST_WIDE_INT
8572 {
8578 }
8580 /* Subroutine of fold_binary. This routine performs all of the
8581 transformations that are common to the equality/inequality
8582 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8583 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8584 fold_binary should call fold_binary. Fold a comparison with
8585 tree code CODE and type TYPE with operands OP0 and OP1. Return
8586 the folded comparison or NULL_TREE. */
8588 static tree
8591 {
8601 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8608 {
8609 const enum tree_code
8616 /* If the constant operation overflowed this can be
8617 simplified as a comparison against INT_MAX/INT_MIN. */
8620 {
8624 /* Get the sign of the constant on the lhs if the
8625 operation were VARIABLE + CONST1. */
8629 /* The sign of the constant determines if we overflowed
8630 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8631 Canonicalize to the INT_MIN overflow by swapping the comparison
8632 if necessary. */
8636 /* We now can look at the canonicalized case
8637 VARIABLE + 1 CODE2 INT_MIN
8638 and decide on the result. */
8640 {
8644 return
8650 return
8655 }
8656 }
8657 else
8658 {
8661 "when changing X +- C1 cmp C2 to "
8663 WARN_STRICT_OVERFLOW_COMPARISON);
8665 }
8666 }
8668 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8670 && equality_code
8672 {
8673 /* ??? The transformation is valid for the other operators if overflow
8674 is undefined for the type, but performing it here badly interacts
8675 with the transformation in fold_cond_expr_with_comparison which
8676 attempts to synthetize ABS_EXPR. */
8680 WARN_STRICT_OVERFLOW_COMPARISON);
8683 }
8685 /* For comparisons of pointers we can decompose it to a compile time
8686 comparison of the base objects and the offsets into the object.
8687 This requires at least one operand being an ADDR_EXPR or a
8688 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8694 {
8697 machine_mode mode;
8701 /* Get base and offset for the access. Strip ADDR_EXPR for
8702 get_inner_reference, but put it back by stripping INDIRECT_REF
8703 off the base object if possible. indirect_baseN will be true
8704 if baseN is not an address but refers to the object itself. */
8707 {
8713 else
8715 }
8717 {
8721 {
8724 }
8727 {
8732 {
8735 }
8736 }
8737 }
8741 {
8747 else
8749 }
8751 {
8755 {
8758 }
8761 {
8766 {
8769 }
8770 }
8771 }
8773 /* A local variable can never be pointed to by
8774 the default SSA name of an incoming parameter. */
8776 && indirect_base0
8779 && !indirect_base1
8784 && indirect_base1
8787 && !indirect_base0
8791 {
8796 }
8797 /* If we have equivalent bases we might be able to simplify. */
8800 {
8801 /* We can fold this expression to a constant if the non-constant
8802 offset parts are equal. */
8811 {
8817 "occur when comparing P +- C1 with "
8819 WARN_STRICT_OVERFLOW_CONDITIONAL);
8822 {
8836 }
8837 }
8838 /* We can simplify the comparison to a comparison of the variable
8839 offset parts if the constant offset parts are equal.
8840 Be careful to use signed sizetype here because otherwise we
8841 mess with array offsets in the wrong way. This is possible
8842 because pointer arithmetic is restricted to retain within an
8843 object and overflow on pointer differences is undefined as of
8844 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8846 && (equality_code
8849 {
8850 /* By converting to signed sizetype we cover middle-end pointer
8851 arithmetic which operates on unsigned pointer types of size
8852 type size and ARRAY_REF offsets which are properly sign or
8853 zero extended from their type in case it is narrower than
8854 sizetype. */
8857 else
8861 else
8868 "occur when comparing P +- C1 with "
8870 WARN_STRICT_OVERFLOW_COMPARISON);
8873 }
8874 }
8875 /* For non-equal bases we can simplify if they are addresses
8876 of local binding decls or constants. */
8878 /* We know that !operand_equal_p (base0, base1, 0)
8879 because the if condition was false. But make
8880 sure two decls are not the same. */
8894 {
8901 }
8902 /* For equal offsets we can simplify to a comparison of the
8903 base addresses. */
8905 && (indirect_base0
8907 && (indirect_base1
8912 {
8918 }
8919 }
8921 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8922 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8923 the resulting offset is smaller in absolute value than the
8924 original one and has the same sign. */
8932 {
8937 tree cst;
8939 "occur when combining constants around "
8942 /* Put the constant on the side where it doesn't overflow and is
8943 of lower absolute value and of same sign than before. */
8950 {
8953 variable1,
8957 }
8965 {
8971 variable2);
8972 }
8973 }
8975 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8976 signed arithmetic case. That form is created by the compiler
8977 often enough for folding it to be of value. One example is in
8978 computing loop trip counts after Operator Strength Reduction. */
8984 {
8990 /* Handle unfolded multiplication by zero. */
8995 "eliminating multiplication in comparison "
8997 WARN_STRICT_OVERFLOW_COMPARISON);
8999 /* If const1 is negative we swap the sense of the comparison. */
9004 }
9011 {
9019 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9025 /* (-a) CMP (-b) -> b CMP a */
9032 {
9033 REAL_VALUE_TYPE cst;
9036 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9043 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9044 /* a CMP (-0) -> a CMP 0 */
9049 /* x != NaN is always true, other ops are always false. */
9052 {
9055 }
9057 /* Fold comparisons against infinity. */
9060 {
9064 }
9065 }
9067 /* If this is a comparison of a real constant with a PLUS_EXPR
9068 or a MINUS_EXPR of a real constant, we can convert it into a
9069 comparison with a revised real constant as long as no overflow
9070 occurs when unsafe_math_optimizations are enabled. */
9082 /* Likewise, we can simplify a comparison of a real constant with
9083 a MINUS_EXPR whose first operand is also a real constant, i.e.
9084 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9085 floating-point types only if -fassociative-math is set. */
9091 arg1))
9096 /* Fold comparisons against built-in math functions. */
9098 && flag_unsafe_math_optimizations
9100 {
9104 {
9108 }
9109 }
9110 }
9114 {
9115 /* If we are widening one operand of an integer comparison,
9116 see if the other operand is similarly being widened. Perhaps we
9117 can do the comparison in the narrower type. */
9122 /* Or if we are changing signedness. */
9126 }
9128 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9129 constant, we can simplify it. */
9134 {
9138 }
9140 /* Simplify comparison of something with itself. (For IEEE
9141 floating-point, we can only do some of these simplifications.) */
9143 {
9145 {
9160 /* For NE, we can only do this simplification if integer
9161 or we don't honor IEEE floating point NaNs. */
9165 /* ... fall through ... */
9171 }
9172 }
9174 /* If we are comparing an expression that just has comparisons
9175 of two integer values, arithmetic expressions of those comparisons,
9176 and constants, we can simplify it. There are only three cases
9177 to check: the two values can either be equal, the first can be
9178 greater, or the second can be greater. Fold the expression for
9179 those three values. Since each value must be 0 or 1, we have
9180 eight possibilities, each of which corresponds to the constant 0
9181 or 1 or one of the six possible comparisons.
9183 This handles common cases like (a > b) == 0 but also handles
9184 expressions like ((x > y) - (y > x)) > 0, which supposedly
9185 occur in macroized code. */
9188 {
9193 /* Don't handle degenerate cases here; they should already
9194 have been handled anyway. */
9203 {
9207 /* We can't just pass T to eval_subst in case cval1 or cval2
9208 was the same as ARG1. */
9210 tree high_result
9214 arg1);
9215 tree equal_result
9219 arg1);
9220 tree low_result
9224 arg1);
9226 /* All three of these results should be 0 or 1. Confirm they are.
9227 Then use those values to select the proper code to use. */
9232 {
9233 /* Make a 3-bit mask with the high-order bit being the
9234 value for `>', the next for '=', and the low for '<'. */
9238 {
9240 /* Always false. */
9261 /* Always true. */
9263 }
9266 {
9270 }
9272 }
9273 }
9274 }
9276 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9277 into a single range test. */
9285 {
9289 }
9291 /* Fold ~X op ~Y as Y op X. */
9294 {
9300 }
9302 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9305 {
9311 }
9314 }
9317 /* Subroutine of fold_binary. Optimize complex multiplications of the
9318 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9319 argument EXPR represents the expression "z" of type TYPE. */
9321 static tree
9323 {
9328 {
9331 }
9333 {
9336 }
9337 else
9338 {
9342 }
9351 }
9354 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9355 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9356 guarantees that P and N have the same least significant log2(M) bits.
9357 N is not otherwise constrained. In particular, N is not normalized to
9358 0 <= N < M as is common. In general, the precise value of P is unknown.
9359 M is chosen as large as possible such that constant N can be determined.
9361 Returns M and sets *RESIDUE to N.
9363 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9364 account. This is not always possible due to PR 35705.
9365 */
9367 static unsigned HOST_WIDE_INT
9370 {
9377 {
9382 }
9384 {
9392 allow_func_align);
9398 {
9401 }
9403 {
9406 {
9409 /* Compute the greatest power-of-2 divisor of op1. */
9413 /* If align is non-zero and less than *modulus, replace
9414 *modulus with align., If align is 0, then either op1 is 0
9415 or the greatest power-of-2 divisor of op1 doesn't fit in an
9416 unsigned HOST_WIDE_INT. In either case, no additional
9417 constraint is imposed. */
9422 }
9423 }
9424 }
9426 /* If we get here, we were unable to determine anything useful about the
9427 expression. */
9429 }
9431 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9432 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9434 static bool
9436 {
9440 {
9443 }
9445 {
9451 else
9453 }
9454 else
9460 }
9462 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9463 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9464 NULL_TREE otherwise. */
9466 static tree
9468 {
9485 {
9489 }
9492 {
9498 }
9499 else
9501 }
9503 /* Try to fold a pointer difference of type TYPE two address expressions of
9504 array references AREF0 and AREF1 using location LOC. Return a
9505 simplified expression for the difference or NULL_TREE. */
9507 static tree
9510 {
9515 /* If the bases are array references as well, recurse. If the bases
9516 are pointer indirections compute the difference of the pointers.
9517 If the bases are equal, we are set. */
9520 && (base_offset
9528 {
9534 base_offset,
9537 }
9539 }
9541 /* If the real or vector real constant CST of type TYPE has an exact
9542 inverse, return it, else return NULL. */
9544 static tree
9546 {
9547 REAL_VALUE_TYPE r;
9549 machine_mode mode;
9553 {
9569 {
9574 }
9580 }
9581 }
9583 /* Mask out the tz least significant bits of X of type TYPE where
9584 tz is the number of trailing zeroes in Y. */
9585 static wide_int
9587 {
9592 }
9594 /* Return true when T is an address and is known to be nonzero.
9595 For floating point we further ensure that T is not denormal.
9596 Similar logic is present in nonzero_address in rtlanal.h.
9598 If the return value is based on the assumption that signed overflow
9599 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9600 change *STRICT_OVERFLOW_P. */
9602 static bool
9604 {
9608 /* Doing something useful for floating point would need more work. */
9614 {
9617 strict_overflow_p);
9623 strict_overflow_p);
9631 }
9634 {
9637 strict_overflow_p);
9645 strict_overflow_p);
9660 strict_overflow_p);
9664 strict_overflow_p);
9667 {
9679 }
9683 }
9685 }
9687 /* Return true when T is an address and is known to be nonzero.
9688 Handle warnings about undefined signed overflow. */
9690 static bool
9692 {
9699 "determining that expression is always "
9701 WARN_STRICT_OVERFLOW_MISC);
9703 }
9705 /* Fold a binary expression of code CODE and type TYPE with operands
9706 OP0 and OP1. LOC is the location of the resulting expression.
9707 Return the folded expression if folding is successful. Otherwise,
9708 return NULL_TREE. */
9710 tree
9713 {
9728 /* Strip any conversions that don't change the mode. This is
9729 safe for every expression, except for a comparison expression
9730 because its signedness is derived from its operands. So, in
9731 the latter case, only strip conversions that don't change the
9732 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9733 preserved.
9735 Note that this is done as an internal manipulation within the
9736 constant folder, in order to find the simplest representation
9737 of the arguments so that their form can be studied. In any
9738 cases, the appropriate type conversions should be put back in
9739 the tree that will get out of the constant folder. */
9742 {
9745 }
9746 else
9747 {
9750 }
9752 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9753 constant but we can't do arithmetic on them. */
9761 {
9763 {
9764 /* Make sure type and arg0 have the same saturating flag. */
9768 }
9771 else
9775 {
9779 }
9780 }
9782 /* If this is a commutative operation, and ARG0 is a constant, move it
9783 to ARG1 to reduce the number of tests below. */
9788 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9789 to ARG1 to reduce the number of tests below. */
9798 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9800 First check for cases where an arithmetic operation is applied to a
9801 compound, conditional, or comparison operation. Push the arithmetic
9802 operation inside the compound or conditional to see if any folding
9803 can then be done. Convert comparison to conditional for this purpose.
9804 The also optimizes non-constant cases that used to be done in
9805 expand_expr.
9807 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9808 one of the operands is a comparison and the other is a comparison, a
9809 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9810 code below would make the expression more complex. Change it to a
9811 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9812 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9825 {
9829 boolean_type_node,
9837 }
9841 {
9843 {
9848 tem);
9849 }
9852 {
9857 tem);
9858 }
9863 {
9869 }
9874 {
9880 }
9881 }
9884 {
9886 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9889 {
9895 }
9897 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9900 {
9901 tree base;
9902 HOST_WIDE_INT coffset;
9911 }
9916 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9922 arg1),
9924 arg0)));
9926 /* PTR_CST +p CST -> CST1 */
9935 {
9936 /* X + (X / CST) * -CST is X % CST. */
9941 {
9950 cst0));
9951 }
9952 }
9954 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9955 one. Make sure the type is not saturating and has the signedness of
9956 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9957 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9964 {
9968 }
9971 {
9972 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9973 with a constant, and the two constants have no bits in common,
9974 we should treat this as a BIT_IOR_EXPR since this may produce more
9975 simplifications. */
9982 {
9985 }
9987 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9988 (plus (plus (mult) (mult)) (foo)) so that we can
9989 take advantage of the factoring cases below. */
9997 {
10003 else
10016 parg0),
10018 marg)),
10022 return
10028 parg1)));
10029 }
10030 }
10031 else
10032 {
10033 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10037 /* Likewise if the operands are reversed. */
10041 /* Convert X + -C into X - C. */
10044 {
10050 }
10052 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10053 to __complex__ ( x, y ). This is not the same for SNaNs or
10054 if signed zeros are involved. */
10058 {
10065 {
10069 {
10075 }
10077 {
10083 }
10084 }
10085 }
10093 /* Convert x+x into x*2.0. */
10099 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10100 We associate floats only if the user has specified
10101 -fassociative-math. */
10105 {
10110 {
10111 tree tree0;
10114 }
10115 }
10116 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10117 We associate floats only if the user has specified
10118 -fassociative-math. */
10122 {
10127 {
10128 tree tree0;
10131 }
10132 }
10133 }
10135 bit_rotate:
10136 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10137 is a rotate of A by C1 bits. */
10138 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10139 is a rotate of A by B bits. */
10140 {
10142 tree rtype;
10151 /* Only create rotates in complete modes. Other cases are not
10152 expanded properly. */
10155 {
10169 {
10175 }
10177 {
10185 element_precision
10189 return
10192 ? LROTATE_EXPR
10196 }
10198 {
10206 element_precision
10210 return fold_convert_loc
10213 ? LROTATE_EXPR
10217 }
10218 }
10219 }
10221 associate:
10222 /* In most languages, can't associate operations on floats through
10223 parentheses. Rather than remember where the parentheses were, we
10224 don't associate floats at all, unless the user has specified
10225 -fassociative-math.
10226 And, we need to make sure type is not saturating. */
10230 {
10236 /* Split both trees into variables, constants, and literals. Then
10237 associate each group together, the constants with literals,
10238 then the result with variables. This increases the chances of
10239 literals being recombined later and of generating relocatable
10240 expressions for the sum of a constant and literal. */
10245 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10249 /* With undefined overflow prefer doing association in a type
10250 which wraps on overflow, if that is one of the operand types. */
10253 {
10261 }
10263 /* With undefined overflow we can only associate constants with one
10264 variable, and constants whose association doesn't overflow. */
10267 {
10269 {
10287 /* The only case we can still associate with two variables
10288 is if they are the same, modulo negation and bit-pattern
10289 preserving conversions. */
10292 }
10293 }
10295 /* Only do something if we found more than two objects. Otherwise,
10296 nothing has changed and we risk infinite recursion. */
10302 {
10314 /* Preserve the MINUS_EXPR if the negative part of the literal is
10315 greater than the positive part. Otherwise, the multiplicative
10316 folding code (i.e extract_muldiv) may be fooled in case
10317 unsigned constants are subtracted, like in the following
10318 example: ((X*2 + 4) - 8U)/2. */
10320 {
10324 {
10328 }
10329 else
10330 {
10334 }
10335 }
10337 /* Don't introduce overflows through reassociation. */
10344 {
10346 return
10350 else
10351 {
10354 return
10358 }
10359 }
10362 return
10365 }
10366 }
10371 /* Pointer simplifications for subtraction, simple reassociations. */
10373 {
10374 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10377 {
10387 }
10388 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10390 {
10397 }
10398 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10399 simplifies. */
10401 {
10408 arg10);
10411 }
10412 }
10413 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10422 /* Convert -A - 1 to ~A. */
10430 /* Convert -1 - A to ~A. */
10436 /* X - (X / Y) * Y is X % Y. */
10444 return
10450 {
10454 /* Fold A - (A & B) into ~B & A. */
10457 {
10459 {
10466 }
10468 {
10475 }
10476 }
10478 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10479 any power of 2 minus 1. */
10484 {
10490 {
10494 }
10495 }
10496 }
10498 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10502 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10503 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10504 (-ARG1 + ARG0) reduces to -ARG1. */
10508 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10509 __complex__ ( x, -y ). This is not the same for SNaNs or if
10510 signed zeros are involved. */
10514 {
10521 {
10525 {
10527 arg1r ? arg1r
10532 }
10534 {
10538 arg1i ? arg1i
10541 }
10542 }
10543 }
10545 /* A - B -> A + (-B) if B is easily negatable. */
10548 /* Avoid this transformation if B is a positive REAL_CST. */
10557 /* Try folding difference of addresses. */
10558 {
10559 HOST_WIDE_INT diff;
10565 }
10567 /* Fold &a[i] - &a[j] to i-j. */
10572 {
10578 }
10581 && flag_unsafe_math_optimizations
10587 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10588 one. Make sure the type is not saturating and has the signedness of
10589 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10590 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10597 {
10601 }
10606 /* (-A) * (-B) -> A * B */
10621 {
10622 /* Transform x * -1 into -x. Make sure to do the negation
10623 on the original operand with conversions not stripped
10624 because we can only strip non-sign-changing conversions. */
10627 /* Transform x * -C into -x * C if x is easily negatable. */
10636 tem);
10638 /* (a * (1 << b)) is (a << b) */
10648 /* (A + A) * C -> A * 2 * C */
10660 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10661 sign-changing only. */
10671 {
10674 "occur when simplifying "
10676 WARN_STRICT_OVERFLOW_MISC);
10678 }
10680 /* Optimize z * conj(z) for integer complex numbers. */
10687 }
10688 else
10689 {
10690 /* Maybe fold x * 0 to 0. The expressions aren't the same
10691 when x is NaN, since x * 0 is also NaN. Nor are they the
10692 same in modes with signed zeros, since multiplying a
10693 negative value by 0 gives -0, not +0. */
10698 /* In IEEE floating point, x*1 is not equivalent to x for snans.
10699 Likewise for complex arithmetic with signed zeros. */
10706 /* Transform x * -1.0 into -x. */
10713 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10714 the result for floating point types due to rounding so it is applied
10715 only if -fassociative-math was specify. */
10720 {
10722 arg1);
10726 }
10728 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10730 {
10733 {
10736 }
10737 }
10739 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10740 This is not the same for NaNs or if signed zeros are
10741 involved. */
10747 {
10750 return
10756 return
10761 }
10763 /* Optimize z * conj(z) for floating point complex numbers.
10764 Guarded by flag_unsafe_math_optimizations as non-finite
10765 imaginary components don't produce scalar results. */
10776 {
10780 /* Optimizations of root(...)*root(...). */
10782 {
10787 /* Optimize sqrt(x)*sqrt(x) as x. */
10793 /* Optimize root(x)*root(y) as root(x*y). */
10797 }
10799 /* Optimize expN(x)*expN(y) as expN(x+y). */
10801 {
10807 }
10809 /* Optimizations of pow(...)*pow(...). */
10813 {
10819 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10821 {
10826 }
10828 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10830 {
10835 }
10836 }
10838 /* Optimize tan(x)*cos(x) as sin(x). */
10847 {
10853 }
10855 /* Optimize x*pow(x,c) as pow(x,c+1). */
10859 {
10865 {
10867 REAL_VALUE_TYPE c;
10868 tree arg;
10874 }
10875 }
10877 /* Optimize pow(x,c)*x as pow(x,c+1). */
10881 {
10887 {
10889 REAL_VALUE_TYPE c;
10890 tree arg;
10896 }
10897 }
10899 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10901 && optimize
10903 {
10907 {
10910 }
10911 }
10912 }
10913 }
10917 bit_ior:
10918 /* ~X | X is -1. */
10921 {
10925 }
10927 /* X | ~X is -1. */
10930 {
10934 }
10936 /* Canonicalize (X & C1) | C2. */
10940 {
10945 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10953 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10958 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10959 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10960 mode which allows further optimizations. */
10965 {
10969 {
10972 }
10973 }
10980 c3)),
10981 arg1);
10982 }
10984 /* (X & ~Y) | (~X & Y) is X ^ Y */
10987 {
11004 }
11010 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11012 This results in more efficient code for machines without a NAND
11013 instruction. Combine will canonicalize to the first form
11014 which will allow use of NAND instructions provided by the
11015 backend if they exist. */
11018 {
11019 return
11026 }
11028 /* See if this can be simplified into a rotate first. If that
11029 is unsuccessful continue in the association code. */
11033 /* ~X ^ X is -1. */
11036 {
11040 }
11042 /* X ^ ~X is -1. */
11045 {
11049 }
11051 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11052 with a constant, and the two constants have no bits in common,
11053 we should treat this as a BIT_IOR_EXPR since this may produce more
11054 simplifications. */
11061 {
11064 }
11066 /* (X | Y) ^ X -> Y & ~ X*/
11069 {
11072 arg1);
11077 }
11079 /* (Y | X) ^ X -> Y & ~ X*/
11082 {
11085 arg1);
11090 }
11092 /* X ^ (X | Y) -> Y & ~ X*/
11095 {
11098 arg0);
11103 }
11105 /* X ^ (Y | X) -> Y & ~ X*/
11108 {
11111 arg0);
11116 }
11118 /* Convert ~X ^ ~Y to X ^ Y. */
11127 /* Convert ~X ^ C to X ^ ~C. */
11135 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11143 /* Fold (X & Y) ^ Y as ~X & Y. */
11146 {
11151 }
11152 /* Fold (X & Y) ^ X as ~Y & X. */
11156 {
11161 }
11162 /* Fold X ^ (X & Y) as X & ~Y. */
11165 {
11170 }
11171 /* Fold X ^ (Y & X) as ~Y & X. */
11175 {
11180 }
11182 /* See if this can be simplified into a rotate first. If that
11183 is unsuccessful continue in the association code. */
11187 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11195 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11203 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11208 {
11209 tree tem2;
11216 }
11217 /* Fold ~X & 1 as (X & 1) == 0. */
11221 {
11222 tree tem2;
11229 }
11230 /* Fold !X & 1 as X == 0. */
11233 {
11237 }
11239 /* Fold (X ^ Y) & Y as ~X & Y. */
11242 {
11247 }
11248 /* Fold (X ^ Y) & X as ~Y & X. */
11252 {
11257 }
11258 /* Fold X & (X ^ Y) as X & ~Y. */
11261 {
11266 }
11267 /* Fold X & (Y ^ X) as ~Y & X. */
11271 {
11276 }
11278 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11279 multiple of 1 << CST. */
11281 {
11288 }
11290 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11291 bits from CST2. */
11295 {
11303 {
11304 /* Avoid the transform if arg1 is a mask of some
11305 mode which allows further optimizations. */
11312 }
11313 }
11315 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11316 ((A & N) + B) & M -> (A + B) & M
11317 Similarly if (N & M) == 0,
11318 ((A | N) + B) & M -> (A + B) & M
11319 and for - instead of + (or unary - instead of +)
11320 and/or ^ instead of |.
11321 If B is constant and (B & M) == 0, fold into A & M. */
11323 {
11332 {
11335 wide_int cst0;
11337 /* Now we know that arg0 is (C + D) or (C - D) or
11338 -C and arg1 (M) is == (1LL << cst) - 1.
11339 Store C into PMOP[0] and D into PMOP[1]. */
11343 {
11346 }
11353 {
11363 {
11366 }
11369 /* If C or D is of the form (A & N) where
11370 (N & M) == M, or of the form (A | N) or
11371 (A ^ N) where (N & M) == 0, replace it with A. */
11375 /* If C or D is a N where (N & M) == 0, it can be
11376 omitted (assumed 0). */
11384 }
11386 /* Only build anything new if we optimized one or both arguments
11387 above. */
11391 {
11394 {
11395 /* Perform the operations in a type that has defined
11396 overflow behavior. */
11402 }
11407 {
11415 else
11417 }
11420 else
11423 /* TEM is now the new binary +, - or unary - replacement. */
11427 }
11428 }
11429 }
11434 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11437 {
11442 return
11444 }
11446 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11448 This results in more efficient code for machines without a NOR
11449 instruction. Combine will canonicalize to the first form
11450 which will allow use of NOR instructions provided by the
11451 backend if they exist. */
11454 {
11461 }
11463 /* If arg0 is derived from the address of an object or function, we may
11464 be able to fold this expression using the object or function's
11465 alignment. */
11467 {
11474 /* This works because modulus is a power of 2. If this weren't the
11475 case, we'd have to replace it by its greatest power-of-2
11476 divisor: modulus & -modulus. */
11479 }
11481 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11482 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11483 if the new mask might be further optimized. */
11492 {
11503 {
11506 /* See if more bits can be proven as zero because of
11507 zero extension. */
11510 {
11515 {
11517 /* See if we can shorten the right shift. */
11520 /* Otherwise X >> C1 is all zeros, so we'll optimize
11521 it into (X, 0) later on by making sure zerobits
11522 is all ones. */
11523 }
11524 }
11527 {
11530 }
11531 /* For arithmetic shift if sign bit could be set, zerobits
11532 can contain actually sign bits, so no transformation is
11533 possible, unless MASK masks them all away. In that
11534 case the shift needs to be converted into logical shift. */
11537 {
11540 else
11542 }
11543 }
11545 /* ((X << 16) & 0xff00) is (X, 0). */
11552 {
11553 /* Only do the transformation if NEWMASK is some integer
11554 mode's mask. */
11561 {
11562 tree newmaskt;
11565 {
11571 }
11572 else
11577 }
11578 }
11579 }
11584 /* Don't touch a floating-point divide by zero unless the mode
11585 of the constant can represent infinity. */
11591 /* Optimize A / A to 1.0 if we don't care about
11592 NaNs or Infinities. Skip the transformation
11593 for non-real operands. */
11598 {
11602 }
11604 /* The complex version of the above A / A optimization. */
11607 {
11611 {
11613 /* omit_two_operands will call fold_convert for us. */
11615 }
11616 }
11618 /* (-A) / (-B) -> A / B */
11628 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11633 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11639 /* If ARG1 is a constant, we can convert this to a multiply by the
11640 reciprocal. This does not have the same rounding properties,
11641 so only do this if -freciprocal-math. We can actually
11642 always safely do it if ARG1 is a power of two, but it's hard to
11643 tell if it is or not in a portable manner. */
11650 {
11654 /* Find the reciprocal if optimizing and the result is exact.
11655 TODO: Complex reciprocal not implemented. */
11657 {
11662 }
11663 }
11664 /* Convert A/B/C to A/(B*C). */
11671 /* Convert A/(B/C) to (A/B)*C. */
11679 /* Convert C1/(X*C2) into (C1/C2)/X. */
11684 {
11690 }
11693 {
11697 /* Optimize sin(x)/cos(x) as tan(x). */
11703 {
11708 }
11710 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11716 {
11720 {
11725 }
11726 }
11728 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11729 NaNs or Infinities. */
11733 {
11740 {
11745 }
11746 }
11748 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11749 NaNs or Infinities. */
11753 {
11760 {
11764 {
11768 tmp);
11769 }
11770 }
11771 }
11773 /* Optimize pow(x,c)/x as pow(x,c-1). */
11777 {
11783 {
11785 REAL_VALUE_TYPE c;
11786 tree arg;
11792 }
11793 }
11795 /* Optimize a/root(b/c) into a*root(c/b). */
11797 {
11801 {
11810 }
11811 }
11813 /* Optimize x/expN(y) into x*expN(-y). */
11815 {
11822 }
11824 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11828 {
11836 }
11837 }
11841 /* Optimize (X & (-A)) / A where A is a power of 2,
11842 to X >> log2(A) */
11846 {
11854 }
11855 }
11857 /* Fall through */
11860 /* Simplify A / (B << N) where A and B are positive and B is
11861 a power of 2, to A >> (N + log2(B)). */
11866 {
11869 {
11877 WARN_STRICT_OVERFLOW_MISC);
11883 }
11884 }
11886 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11887 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11893 /* Fall through */
11900 /* X / -1 is -X. */
11906 /* Convert -A / -B to A / B when the type is signed and overflow is
11907 undefined. */
11911 {
11914 "when distributing negation across "
11916 WARN_STRICT_OVERFLOW_MISC);
11922 }
11926 {
11929 "when distributing negation across "
11931 WARN_STRICT_OVERFLOW_MISC);
11937 }
11939 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11940 operation, EXACT_DIV_EXPR.
11942 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11943 At one time others generated faster code, it's not clear if they do
11944 after the last round to changes to the DIV code in expmed.c. */
11953 {
11957 WARN_STRICT_OVERFLOW_MISC);
11959 }
11967 /* X % -1 is zero. */
11973 /* X % -C is the same as X % C. */
11980 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11987 /* X % -Y is the same as X % Y. */
12000 {
12004 WARN_STRICT_OVERFLOW_MISC);
12006 }
12008 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12009 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12013 {
12015 /* Also optimize A % (C << N) where C is a power of 2,
12016 to A & ((C << N) - 1). */
12021 {
12022 tree mask
12027 "occur when simplifying "
12029 WARN_STRICT_OVERFLOW_MISC);
12033 }
12034 }
12045 /* Optimize -1 >> x for arithmetic right shifts. */
12049 /* ... fall through ... */
12052 shift:
12058 /* Prefer vector1 << scalar to vector1 << vector2
12059 if vector2 is uniform. */
12064 /* Since negative shift count is not well-defined,
12065 don't try to compute it in the compiler. */
12071 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12076 {
12080 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12081 being well defined. */
12083 {
12089 else
12091 }
12095 }
12097 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12098 into x & ((unsigned)-1 >> c) for unsigned types. */
12106 {
12109 tree lshift;
12110 tree arg00;
12113 {
12120 }
12121 }
12123 /* Rewrite an LROTATE_EXPR by a constant into an
12124 RROTATE_EXPR by a new constant. */
12126 {
12130 }
12132 /* If we have a rotate of a bit operation with the rotate count and
12133 the second operand of the bit operation both constant,
12134 permute the two operations. */
12146 /* Two consecutive rotates adding up to the some integer
12147 multiple of the precision of the type can be ignored. */
12155 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12156 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12157 if the latter can be further optimized. */
12162 {
12166 arg1);
12170 arg1);
12174 }
12202 /* Note that the operands of this must be ints
12203 and their values must be 0 or 1.
12204 ("true" is a fixed value perhaps depending on the language.) */
12205 /* If first arg is constant zero, return it. */
12209 /* If either arg is constant true, drop it. */
12213 /* Preserve sequence points. */
12216 /* If second arg is constant zero, result is zero, but first arg
12217 must be evaluated. */
12220 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12221 case will be handled here. */
12225 /* !X && X is always false. */
12229 /* X && !X is always false. */
12234 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12235 means A >= Y && A != MAX, but in this case we know that
12236 A < X <= MAX. */
12240 {
12248 }
12257 /* Note that the operands of this must be ints
12258 and their values must be 0 or true.
12259 ("true" is a fixed value perhaps depending on the language.) */
12260 /* If first arg is constant true, return it. */
12264 /* If either arg is constant zero, drop it. */
12268 /* Preserve sequence points. */
12271 /* If second arg is constant true, result is true, but we must
12272 evaluate first arg. */
12275 /* Likewise for first arg, but note this only occurs here for
12276 TRUTH_OR_EXPR. */
12280 /* !X || X is always true. */
12284 /* X || !X is always true. */
12289 /* (X && !Y) || (!X && Y) is X ^ Y */
12292 {
12309 }
12318 /* If the second arg is constant zero, drop it. */
12321 /* If the second arg is constant true, this is a logical inversion. */
12323 {
12326 }
12327 /* Identical arguments cancel to zero. */
12331 /* !X ^ X is always true. */
12336 /* X ^ !X is always true. */
12352 /* bool_var != 0 becomes bool_var. */
12357 /* bool_var == 1 becomes bool_var. */
12362 /* bool_var != 1 becomes !bool_var. */
12369 /* bool_var == 0 becomes !bool_var. */
12376 /* !exp != 0 becomes !exp */
12381 /* If this is an equality comparison of the address of two non-weak,
12382 unaliased symbols neither of which are extern (since we do not
12383 have access to attributes for externs), then we know the result. */
12396 {
12397 /* We know that we're looking at the address of two
12398 non-weak, unaliased, static _DECL nodes.
12400 It is both wasteful and incorrect to call operand_equal_p
12401 to compare the two ADDR_EXPR nodes. It is wasteful in that
12402 all we need to do is test pointer equality for the arguments
12403 to the two ADDR_EXPR nodes. It is incorrect to use
12404 operand_equal_p as that function is NOT equivalent to a
12405 C equality test. It can in fact return false for two
12406 objects which would test as equal using the C equality
12407 operator. */
12411 type);
12412 }
12414 /* Similarly for a NEGATE_EXPR. */
12418 arg1)))
12423 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12431 arg1),
12434 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12443 {
12447 val,
12451 }
12453 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12460 {
12462 code == NE_EXPR
12465 }
12467 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12472 /* If this is an EQ or NE comparison with zero and ARG0 is
12473 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12474 two operations, but the latter can be done in one less insn
12475 on machines that have only two-operand insns or on which a
12476 constant cannot be the first operand. */
12479 {
12484 {
12491 arg1);
12492 }
12495 {
12502 arg1);
12503 }
12504 }
12506 /* If this is an NE or EQ comparison of zero against the result of a
12507 signed MOD operation whose second operand is a power of 2, make
12508 the MOD operation unsigned since it is simpler and equivalent. */
12516 {
12526 }
12528 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12529 C1 is a valid shift constant, and C2 is a power of two, i.e.
12530 a single bit. */
12534 == INTEGER_CST
12537 {
12542 /* Check for a valid shift count. */
12544 {
12548 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12549 can be rewritten as (X & (C2 << C1)) != 0. */
12551 {
12556 }
12557 /* Otherwise, for signed (arithmetic) shifts,
12558 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12559 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12563 /* Otherwise, of unsigned (logical) shifts,
12564 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12565 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12566 else
12570 arg000);
12571 }
12572 }
12574 /* If we have (A & C) == C where C is a power of 2, convert this into
12575 (A & C) != 0. Similarly for NE_EXPR. */
12581 integer_zero_node));
12583 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12584 bit, then fold the expression into A < 0 or A >= 0. */
12589 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12590 Similarly for NE_EXPR. */
12594 {
12598 tree dandnotc
12601 notc);
12605 }
12607 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12608 Similarly for NE_EXPR. */
12612 {
12614 tree candnotd
12621 }
12623 /* If this is a comparison of a field, we may be able to simplify it. */
12626 /* Handle the constant case even without -O
12627 to make sure the warnings are given. */
12629 {
12633 }
12635 /* Optimize comparisons of strlen vs zero to a compare of the
12636 first character of the string vs zero. To wit,
12637 strlen(ptr) == 0 => *ptr == 0
12638 strlen(ptr) != 0 => *ptr != 0
12639 Other cases should reduce to one of these two (or a constant)
12640 due to the return value of strlen being unsigned. */
12643 {
12651 {
12656 }
12657 }
12659 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12660 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12664 {
12669 {
12671 {
12674 }
12677 }
12678 }
12680 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12686 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12691 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12698 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12706 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12707 (X & C) == 0 when C is a single bit. */
12712 {
12719 arg1));
12720 }
12722 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12723 constant C is a power of two, i.e. a single bit. */
12730 {
12734 }
12736 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12737 when is C is a power of two, i.e. a single bit. */
12744 {
12750 }
12754 {
12757 }
12759 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12767 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12770 {
12783 arg01),
12792 arg01),
12801 arg00),
12810 arg00),
12812 }
12816 {
12823 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12824 operand_equal_p guarantees no side-effects so we don't need
12825 to use omit_one_operand on Z. */
12829 arg10));
12833 arg11));
12837 arg10));
12841 arg11));
12843 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12846 {
12852 }
12853 }
12855 /* Attempt to simplify equality/inequality comparisons of complex
12856 values. Only lower the comparison if the result is known or
12857 can be simplified to a single scalar comparison. */
12862 {
12867 {
12870 }
12871 else
12872 {
12875 }
12878 {
12881 }
12882 else
12883 {
12886 }
12890 {
12892 {
12897 }
12898 else
12899 {
12904 }
12905 }
12909 {
12911 {
12916 }
12917 else
12918 {
12923 }
12924 }
12925 }
12937 /* Transform comparisons of the form X +- C CMP X. */
12944 {
12951 else
12954 /* (X - c) > X becomes false. */
12958 {
12962 "occur when assuming that (X - c) > X "
12964 WARN_STRICT_OVERFLOW_ALL);
12966 }
12968 /* Likewise (X + c) < X becomes false. */
12972 {
12976 "occur when assuming that "
12978 WARN_STRICT_OVERFLOW_ALL);
12980 }
12982 /* Convert (X - c) <= X to true. */
12987 {
12991 "occur when assuming that "
12993 WARN_STRICT_OVERFLOW_ALL);
12995 }
12997 /* Convert (X + c) >= X to true. */
13002 {
13006 "occur when assuming that "
13008 WARN_STRICT_OVERFLOW_ALL);
13010 }
13013 {
13014 /* Convert X + c > X and X - c < X to true for integers. */
13018 {
13021 "not occur when assuming that "
13023 WARN_STRICT_OVERFLOW_ALL);
13025 }
13030 {
13033 "not occur when assuming that "
13035 WARN_STRICT_OVERFLOW_ALL);
13037 }
13039 /* Convert X + c <= X and X - c >= X to false for integers. */
13043 {
13046 "not occur when assuming that "
13048 WARN_STRICT_OVERFLOW_ALL);
13050 }
13055 {
13058 "not occur when assuming that "
13060 WARN_STRICT_OVERFLOW_ALL);
13062 }
13063 }
13064 }
13066 /* Comparisons with the highest or lowest possible integer of
13067 the specified precision will have known values. */
13068 {
13074 {
13081 {
13094 /* The GE_EXPR and LT_EXPR cases above are not normally
13095 reached because of previous transformations. */
13099 }
13102 {
13109 arg1);
13115 arg0),
13116 arg1);
13119 }
13122 {
13137 }
13140 {
13147 arg1);
13153 arg0),
13154 arg1);
13157 }
13161 /* We will flip the signedness of the comparison operator
13162 associated with the mode of arg1, so the sign bit is
13163 specified by this mode. Check that arg1 is the signed
13164 max associated with this sign bit. */
13166 /* signed_type does not work on pointer types. */
13168 {
13169 /* The following case also applies to X < signed_max+1
13170 and X >= signed_max+1 because previous transformations. */
13172 {
13178 }
13179 }
13180 }
13181 }
13183 /* If we are comparing an ABS_EXPR with a constant, we can
13184 convert all the cases into explicit comparisons, but they may
13185 well not be faster than doing the ABS and one comparison.
13186 But ABS (X) <= C is a range comparison, which becomes a subtraction
13187 and a comparison, and is probably faster. */
13201 /* Convert ABS_EXPR<x> >= 0 to true. */
13208 {
13211 "when simplifying comparison of "
13213 WARN_STRICT_OVERFLOW_CONDITIONAL);
13216 arg0);
13217 }
13219 /* Convert ABS_EXPR<x> < 0 to false. */
13224 {
13227 "when simplifying comparison of "
13229 WARN_STRICT_OVERFLOW_CONDITIONAL);
13232 arg0);
13233 }
13235 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13236 and similarly for >= into !=. */
13246 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13247 otherwise Y might be >= # of bits in X's type and thus e.g.
13248 (unsigned char) (1 << Y) for Y 15 might be 0.
13249 If the cast is widening, then 1 << Y should have unsigned type,
13250 otherwise if Y is number of bits in the signed shift type minus 1,
13251 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13252 31 might be 0xffffffff80000000. */
13263 {
13269 }
13282 {
13286 }
13288 /* If the first operand is NaN, the result is constant. */
13292 {
13294 ? integer_zero_node
13297 }
13299 /* If the second operand is NaN, the result is constant. */
13303 {
13305 ? integer_zero_node
13308 }
13310 /* Simplify unordered comparison of something with itself. */
13316 && !flag_trapping_math
13320 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13321 {
13333 }
13338 /* When pedantic, a compound expression can be neither an lvalue
13339 nor an integer constant expression. */
13342 /* Don't let (0, 0) be null pointer constant. */
13363 /* An ASSERT_EXPR should never be passed to fold_binary. */
13368 {
13383 {
13389 }
13392 }
13398 {
13423 {
13436 }
13439 }
13444 }
13446 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13447 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13448 of GOTO_EXPR. */
13450 static tree
13452 {
13454 {
13461 /* ... fall through ... */
13465 }
13466 }
13468 /* Return whether the sub-tree ST contains a label which is accessible from
13469 outside the sub-tree. */
13471 static bool
13473 {
13474 return
13476 }
13478 /* Fold a ternary expression of code CODE and type TYPE with operands
13479 OP0, OP1, and OP2. Return the folded expression if folding is
13480 successful. Otherwise, return NULL_TREE. */
13482 tree
13485 {
13486 tree tem;
13493 /* If this is a commutative operation, and OP0 is a constant, move it
13494 to OP1 to reduce the number of tests below. */
13503 /* Strip any conversions that don't change the mode. This is safe
13504 for every expression, except for a comparison expression because
13505 its signedness is derived from its operands. So, in the latter
13506 case, only strip conversions that don't change the signedness.
13508 Note that this is done as an internal manipulation within the
13509 constant folder, in order to find the simplest representation of
13510 the arguments so that their form can be studied. In any cases,
13511 the appropriate type conversions should be put back in the tree
13512 that will get out of the constant folder. */
13514 {
13517 }
13520 {
13523 }
13526 {
13529 }
13532 {
13536 {
13542 }
13547 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13548 so all simple results must be passed through pedantic_non_lvalue. */
13550 {
13553 /* Only optimize constant conditions when the selected branch
13554 has the same type as the COND_EXPR. This avoids optimizing
13555 away "c ? x : throw", where the throw has a void type.
13556 Avoid throwing away that operand which contains label. */
13563 }
13565 {
13575 {
13580 {
13588 }
13592 }
13593 }
13598 /* If we have A op B ? A : C, we may be able to convert this to a
13599 simpler expression, depending on the operation and the values
13600 of B and C. Signed zeros prevent all of these transformations,
13601 for reasons given above each one.
13603 Also try swapping the arguments and inverting the conditional. */
13608 {
13612 }
13616 op2,
13619 {
13623 {
13627 }
13628 }
13630 /* If the second operand is simpler than the third, swap them
13631 since that produces better jump optimization results. */
13634 {
13636 /* See if this can be inverted. If it can't, possibly because
13637 it was a floating-point inequality comparison, don't do
13638 anything. */
13642 }
13644 /* Convert A ? 1 : 0 to simply A. */
13649 /* If we try to convert OP0 to our type, the
13650 call to fold will try to move the conversion inside
13651 a COND, which will recurse. In that case, the COND_EXPR
13652 is probably the best choice, so leave it alone. */
13656 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13657 over COND_EXPR in cases such as floating point comparisons. */
13666 arg0)));
13668 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13673 {
13674 /* sign_bit_p looks through both zero and sign extensions,
13675 but for this optimization only sign extensions are
13676 usable. */
13679 {
13682 {
13685 }
13687 }
13688 /* sign_bit_p only checks ARG1 bits within A's precision.
13689 If <sign bit of A> has wider type than A, bits outside
13690 of A's precision in <sign bit of A> need to be checked.
13691 If they are all 0, this optimization needs to be done
13692 in unsigned A's type, if they are all 1 in signed A's type,
13693 otherwise this can't be done. */
13699 {
13701 tree tem_type;
13714 {
13717 }
13719 {
13722 }
13723 else
13725 }
13728 return
13734 arg1)));
13735 }
13737 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13738 already handled above. */
13743 {
13752 }
13754 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13755 is probably obsolete because the first operand should be a
13756 truth value (that's why we have the two cases above), but let's
13757 leave it in until we can confirm this for all front-ends. */
13769 /* Disable the transformations below for vectors, since
13770 fold_binary_op_with_conditional_arg may undo them immediately,
13771 yielding an infinite loop. */
13775 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13784 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13789 {
13791 /* Only perform transformation if ARG0 is easily inverted. */
13795 ? BIT_IOR_EXPR
13798 arg1);
13799 }
13801 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13806 {
13808 /* Only perform transformation if ARG0 is easily inverted. */
13814 op2);
13815 }
13817 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13829 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13830 of fold_ternary on them. */
13840 {
13850 {
13855 {
13863 }
13865 /* Constructor elements can be subvectors. */
13868 {
13872 }
13874 /* We keep an exact subset of the constructor elements. */
13876 {
13882 {
13886 }
13894 CONSTRUCTOR_ELT
13897 }
13898 /* The bitfield references a single constructor element. */
13900 {
13905 else
13909 }
13910 }
13911 }
13913 /* A bit-field-ref that referenced the full argument can be stripped. */
13919 /* On constants we can use native encode/interpret to constant
13920 fold (nearly) all BIT_FIELD_REFs. */
13924 /* This limitation should not be necessary, we just need to
13925 round this up to mode size. */
13927 /* Need bit-shifting of the buffer to relax the following. */
13929 {
13934 /* ??? We cannot tell native_encode_expr to start at
13935 some random byte only. So limit us to a reasonable amount
13936 of work. */
13938 {
13943 {
13949 }
13950 }
13951 }
13956 /* For integers we can decompose the FMA if possible. */
13968 {
13984 {
13989 /* Make sure that the perm value is in an acceptable
13990 range. */
13999 else
14004 }
14007 {
14012 }
14017 {
14022 }
14028 {
14032 }
14037 /* Some targets are deficient and fail to expand a single
14038 argument permutation while still allowing an equivalent
14039 2-argument version. */
14043 {
14046 }
14049 {
14056 }
14060 }
14066 }
14068 /* Perform constant folding and related simplification of EXPR.
14069 The related simplifications include x*1 => x, x*0 => 0, etc.,
14070 and application of the associative law.
14071 NOP_EXPR conversions may be removed freely (as long as we
14072 are careful not to change the type of the overall expression).
14073 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14074 but we can constant-fold them if they have constant operands. */
14076 #ifdef ENABLE_FOLD_CHECKING
14077 # define fold(x) fold_1 (x)
14079 static
14080 #endif
14081 tree
14083 {
14087 tree tem;
14090 /* Return right away if a constant. */
14094 /* CALL_EXPR-like objects with variable numbers of operands are
14095 treated specially. */
14097 {
14099 {
14102 }
14104 }
14107 {
14112 {
14130 }
14131 }
14134 {
14136 {
14143 {
14148 /* Find a matching index by means of a binary search. */
14150 {
14166 else
14168 }
14169 }
14172 }
14174 /* Return a VECTOR_CST if possible. */
14176 {
14183 tree value;
14186 {
14190 {
14193 }
14194 else
14196 }
14201 }
14209 }
14211 #ifdef ENABLE_FOLD_CHECKING
14212 #undef fold
14219 /* When --enable-checking=fold, compute a digest of expr before
14220 and after actual fold call to see if fold did not accidentally
14221 change original expr. */
14223 tree
14225 {
14226 tree ret;
14246 }
14248 void
14250 {
14261 }
14263 static void
14265 {
14267 }
14269 static void
14272 {
14278 recursive_label:
14288 {
14289 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14293 }
14300 {
14301 /* Allow these fields to be modified. */
14302 tree tmp;
14310 {
14313 }
14314 }
14325 {
14328 {
14343 }
14347 {
14360 }
14377 {
14383 }
14386 {
14388 {
14391 }
14393 }
14404 {
14407 }
14417 }
14418 }
14420 /* Helper function for outputting the checksum of a tree T. When
14421 debugging with gdb, you can "define mynext" to be "next" followed
14422 by "call debug_fold_checksum (op0)", then just trace down till the
14423 outputs differ. */
14425 DEBUG_FUNCTION void
14427 {
14442 }
14444 #endif
14446 /* Fold a unary tree expression with code CODE of type TYPE with an
14447 operand OP0. LOC is the location of the resulting expression.
14448 Return a folded expression if successful. Otherwise, return a tree
14449 expression with code CODE of type TYPE with an operand OP0. */
14451 tree
14454 {
14455 tree tem;
14456 #ifdef ENABLE_FOLD_CHECKING
14465 #endif
14471 #ifdef ENABLE_FOLD_CHECKING
14478 #endif
14480 }
14482 /* Fold a binary tree expression with code CODE of type TYPE with
14483 operands OP0 and OP1. LOC is the location of the resulting
14484 expression. Return a folded expression if successful. Otherwise,
14485 return a tree expression with code CODE of type TYPE with operands
14486 OP0 and OP1. */
14488 tree
14491 MEM_STAT_DECL)
14492 {
14493 tree tem;
14494 #ifdef ENABLE_FOLD_CHECKING
14511 #endif
14517 #ifdef ENABLE_FOLD_CHECKING
14532 #endif
14534 }
14536 /* Fold a ternary tree expression with code CODE of type TYPE with
14537 operands OP0, OP1, and OP2. Return a folded expression if
14538 successful. Otherwise, return a tree expression with code CODE of
14539 type TYPE with operands OP0, OP1, and OP2. */
14541 tree
14544 {
14545 tree tem;
14546 #ifdef ENABLE_FOLD_CHECKING
14570 #endif
14577 #ifdef ENABLE_FOLD_CHECKING
14600 #endif
14602 }
14604 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14605 arguments in ARGARRAY, and a null static chain.
14606 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14607 of type TYPE from the given operands as constructed by build_call_array. */
14609 tree
14612 {
14613 tree tem;
14614 #ifdef ENABLE_FOLD_CHECKING
14633 #endif
14637 #ifdef ENABLE_FOLD_CHECKING
14653 #endif
14655 }
14657 /* Perform constant folding and related simplification of initializer
14658 expression EXPR. These behave identically to "fold_buildN" but ignore
14659 potential run-time traps and exceptions that fold must preserve. */
14661 #define START_FOLD_INIT \
14662 int saved_signaling_nans = flag_signaling_nans;\
14663 int saved_trapping_math = flag_trapping_math;\
14664 int saved_rounding_math = flag_rounding_math;\
14665 int saved_trapv = flag_trapv;\
14666 int saved_folding_initializer = folding_initializer;\
14667 flag_signaling_nans = 0;\
14668 flag_trapping_math = 0;\
14669 flag_rounding_math = 0;\
14670 flag_trapv = 0;\
14671 folding_initializer = 1;
14673 #define END_FOLD_INIT \
14674 flag_signaling_nans = saved_signaling_nans;\
14675 flag_trapping_math = saved_trapping_math;\
14676 flag_rounding_math = saved_rounding_math;\
14677 flag_trapv = saved_trapv;\
14678 folding_initializer = saved_folding_initializer;
14680 tree
14683 {
14684 tree result;
14685 START_FOLD_INIT;
14689 END_FOLD_INIT;
14691 }
14693 tree
14696 {
14697 tree result;
14698 START_FOLD_INIT;
14702 END_FOLD_INIT;
14704 }
14706 tree
14709 {
14710 tree result;
14711 START_FOLD_INIT;
14715 END_FOLD_INIT;
14717 }
14719 #undef START_FOLD_INIT
14720 #undef END_FOLD_INIT
14722 /* Determine if first argument is a multiple of second argument. Return 0 if
14723 it is not, or we cannot easily determined it to be.
14725 An example of the sort of thing we care about (at this point; this routine
14726 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14727 fold cases do now) is discovering that
14729 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14731 is a multiple of
14733 SAVE_EXPR (J * 8)
14735 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14737 This code also handles discovering that
14739 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14741 is a multiple of 8 so we don't have to worry about dealing with a
14742 possible remainder.
14744 Note that we *look* inside a SAVE_EXPR only to determine how it was
14745 calculated; it is not safe for fold to do much of anything else with the
14746 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14747 at run time. For example, the latter example above *cannot* be implemented
14748 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14749 evaluation time of the original SAVE_EXPR is not necessarily the same at
14750 the time the new expression is evaluated. The only optimization of this
14751 sort that would be valid is changing
14753 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14755 divided by 8 to
14757 SAVE_EXPR (I) * SAVE_EXPR (J)
14759 (where the same SAVE_EXPR (J) is used in the original and the
14760 transformed version). */
14762 int
14764 {
14772 {
14774 /* Bitwise and provides a power of two multiple. If the mask is
14775 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14778 /* FALLTHRU */
14791 {
14795 /* const_binop may not detect overflow correctly,
14796 so check for it explicitly here. */
14800 size_one_node,
14801 op1)))
14804 }
14808 /* Can't handle conversions from non-integral or wider integral type. */
14814 /* .. fall through ... */
14831 SIGNED);
14835 }
14836 }
14838 /* Return true if CODE or TYPE is known to be non-negative. */
14840 static bool
14842 {
14845 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14846 have a signed:1 type (where the value is -1 and 0). */
14849 }
14851 /* Return true if (CODE OP0) is known to be non-negative. If the return
14852 value is based on the assumption that signed overflow is undefined,
14853 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14854 *STRICT_OVERFLOW_P. */
14856 bool
14859 {
14864 {
14866 /* We can't return 1 if flag_wrapv is set because
14867 ABS_EXPR<INT_MIN> = INT_MIN. */
14871 {
14874 }
14881 strict_overflow_p);
14884 {
14889 {
14892 strict_overflow_p);
14894 {
14898 strict_overflow_p);
14899 }
14900 }
14902 {
14905 strict_overflow_p);
14909 }
14910 }
14915 }
14917 /* We don't know sign of `t', so be conservative and return false. */
14919 }
14921 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14922 value is based on the assumption that signed overflow is undefined,
14923 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14924 *STRICT_OVERFLOW_P. */
14926 bool
14929 {
14934 {
14939 strict_overflow_p)
14941 strict_overflow_p));
14943 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14944 both unsigned and at least 2 bits shorter than the result. */
14948 {
14953 {
14957 }
14958 }
14963 {
14964 /* x * x is always non-negative for floating point x
14965 or without overflow. */
14969 {
14973 }
14974 }
14976 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14977 both unsigned and their total bits is shorter than the result. */
14981 {
15000 {
15010 }
15011 }
15017 strict_overflow_p)
15019 strict_overflow_p));
15030 strict_overflow_p)
15032 strict_overflow_p));
15039 strict_overflow_p);
15042 }
15044 /* We don't know sign of `t', so be conservative and return false. */
15046 }
15048 /* Return true if T is known to be non-negative. If the return
15049 value is based on the assumption that signed overflow is undefined,
15050 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15051 *STRICT_OVERFLOW_P. */
15053 bool
15055 {
15060 {
15072 strict_overflow_p)
15074 strict_overflow_p));
15078 }
15079 /* We don't know sign of `t', so be conservative and return false. */
15081 }
15083 /* Return true if T is known to be non-negative. If the return
15084 value is based on the assumption that signed overflow is undefined,
15085 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15086 *STRICT_OVERFLOW_P. */
15088 bool
15091 {
15094 {
15114 /* Always true. */
15118 /* sqrt(-0.0) is -0.0. */
15122 strict_overflow_p);
15159 /* True if the 1st argument is nonnegative. */
15161 strict_overflow_p);
15164 /* True if the 1st OR 2nd arguments are nonnegative. */
15166 strict_overflow_p)
15168 strict_overflow_p)));
15171 /* True if the 1st AND 2nd arguments are nonnegative. */
15173 strict_overflow_p)
15175 strict_overflow_p)));
15178 /* True if the 2nd argument is nonnegative. */
15180 strict_overflow_p);
15183 /* True if the 1st argument is nonnegative or the second
15184 argument is an even integer. */
15189 strict_overflow_p);
15192 /* True if the 1st argument is nonnegative or the second
15193 argument is an even integer valued real. */
15195 {
15196 REAL_VALUE_TYPE c;
15197 HOST_WIDE_INT n;
15202 {
15203 REAL_VALUE_TYPE cint;
15207 }
15208 }
15210 strict_overflow_p);
15214 }
15216 type);
15217 }
15219 /* Return true if T is known to be non-negative. If the return
15220 value is based on the assumption that signed overflow is undefined,
15221 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15222 *STRICT_OVERFLOW_P. */
15224 static bool
15226 {
15232 {
15234 {
15238 /* If the initializer is non-void, then it's a normal expression
15239 that will be assigned to the slot. */
15243 /* Otherwise, the initializer sets the slot in some way. One common
15244 way is an assignment statement at the end of the initializer. */
15246 {
15254 else
15256 }
15260 strict_overflow_p);
15263 }
15266 {
15272 arg0,
15273 arg1,
15274 strict_overflow_p);
15275 }
15279 strict_overflow_p);
15282 strict_overflow_p);
15285 strict_overflow_p);
15290 }
15292 /* We don't know sign of `t', so be conservative and return false. */
15294 }
15296 /* Return true if T is known to be non-negative. If the return
15297 value is based on the assumption that signed overflow is undefined,
15298 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15299 *STRICT_OVERFLOW_P. */
15301 bool
15303 {
15310 {
15317 strict_overflow_p);
15323 strict_overflow_p);
15332 }
15335 {
15343 strict_overflow_p);
15348 strict_overflow_p);
15361 }
15362 }
15364 /* Return true if `t' is known to be non-negative. Handle warnings
15365 about undefined signed overflow. */
15367 bool
15369 {
15376 "determining that expression is always "
15378 WARN_STRICT_OVERFLOW_MISC);
15380 }
15383 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15384 For floating point we further ensure that T is not denormal.
15385 Similar logic is present in nonzero_address in rtlanal.h.
15387 If the return value is based on the assumption that signed overflow
15388 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15389 change *STRICT_OVERFLOW_P. */
15391 bool
15394 {
15396 {
15399 strict_overflow_p);
15402 {
15408 strict_overflow_p));
15409 }
15414 strict_overflow_p);
15418 }
15421 }
15423 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15424 For floating point we further ensure that T is not denormal.
15425 Similar logic is present in nonzero_address in rtlanal.h.
15427 If the return value is based on the assumption that signed overflow
15428 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15429 change *STRICT_OVERFLOW_P. */
15431 bool
15433 tree type,
15434 tree op0,
15436 {
15439 {
15443 {
15444 /* With the presence of negative values it is hard
15445 to say something. */
15452 /* One of operands must be positive and the other non-negative. */
15453 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15454 overflows, on a twos-complement machine the sum of two
15455 nonnegative numbers can never be zero. */
15457 strict_overflow_p)
15459 strict_overflow_p));
15460 }
15465 {
15467 strict_overflow_p)
15469 strict_overflow_p))
15470 {
15473 }
15474 }
15483 {
15486 }
15493 {
15497 /* When both operands are nonzero, then MAX must be too. */
15499 strict_overflow_p))
15502 /* MAX where operand 0 is positive is positive. */
15504 strict_overflow_p);
15505 }
15506 /* MAX where operand 1 is positive is positive. */
15511 {
15515 }
15520 strict_overflow_p)
15522 strict_overflow_p));
15526 }
15529 }
15531 /* Return true when T is an address and is known to be nonzero.
15532 For floating point we further ensure that T is not denormal.
15533 Similar logic is present in nonzero_address in rtlanal.h.
15535 If the return value is based on the assumption that signed overflow
15536 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15537 change *STRICT_OVERFLOW_P. */
15539 bool
15541 {
15544 {
15549 {
15558 /* For objects in symbol table check if we know they are non-zero.
15559 Don't do anything for variables and functions before symtab is built;
15560 it is quite possible that they will be declared weak later. */
15562 {
15568 else
15570 }
15572 /* Function local objects are never NULL. */
15579 /* Constants are never weak. */
15584 }
15592 {
15596 }
15601 }
15603 }
15605 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15606 attempt to fold the expression to a constant without modifying TYPE,
15607 OP0 or OP1.
15609 If the expression could be simplified to a constant, then return
15610 the constant. If the expression would not be simplified to a
15611 constant, then return NULL_TREE. */
15613 tree
15615 {
15618 }
15620 /* Given the components of a unary expression CODE, TYPE and OP0,
15621 attempt to fold the expression to a constant without modifying
15622 TYPE or OP0.
15624 If the expression could be simplified to a constant, then return
15625 the constant. If the expression would not be simplified to a
15626 constant, then return NULL_TREE. */
15628 tree
15630 {
15633 }
15635 /* If EXP represents referencing an element in a constant string
15636 (either via pointer arithmetic or array indexing), return the
15637 tree representing the value accessed, otherwise return NULL. */
15639 tree
15641 {
15645 {
15647 tree index;
15648 tree string;
15653 else
15654 {
15658 /* Optimize the special-case of a zero lower bound.
15660 We convert the low_bound to sizetype to avoid some problems
15661 with constant folding. (E.g. suppose the lower bound is 1,
15662 and its mode is QI. Without the conversion,l (ARRAY
15663 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15664 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15670 }
15683 }
15685 }
15687 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15688 an integer constant, real, or fixed-point constant.
15690 TYPE is the type of the result. */
15692 static tree
15694 {
15698 {
15700 {
15707 }
15714 {
15715 FIXED_VALUE_TYPE f;
15720 /* Propagate overflow flags. */
15724 }
15728 }
15731 }
15733 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15734 an integer constant or real constant.
15736 TYPE is the type of the result. */
15738 tree
15740 {
15744 {
15746 {
15747 /* If the value is unsigned or non-negative, then the absolute value
15748 is the same as the ordinary value. */
15752 /* If the value is negative, then the absolute value is
15753 its negation. */
15754 else
15755 {
15760 }
15761 }
15767 else
15773 }
15776 }
15778 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15779 constant. TYPE is the type of the result. */
15781 static tree
15783 {
15787 }
15789 /* Given CODE, a relational operator, the target type, TYPE and two
15790 constant operands OP0 and OP1, return the result of the
15791 relational operation. If the result is not a compile time
15792 constant, then return NULL_TREE. */
15794 static tree
15796 {
15799 /* From here on, the only cases we handle are when the result is
15800 known to be a constant. */
15803 {
15807 /* Handle the cases where either operand is a NaN. */
15809 {
15811 {
15839 }
15842 }
15845 }
15848 {
15852 }
15854 /* Handle equality/inequality of complex constants. */
15856 {
15867 else
15869 }
15872 {
15879 {
15891 }
15894 }
15896 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15898 To compute GT, swap the arguments and do LT.
15899 To compute GE, do LT and invert the result.
15900 To compute LE, swap the arguments, do LT and invert the result.
15901 To compute NE, do EQ and invert the result.
15903 Therefore, the code below must handle only EQ and LT. */
15906 {
15911 }
15913 /* Note that it is safe to invert for real values here because we
15914 have already handled the one case that it matters. */
15918 {
15921 }
15923 /* Compute a result for LT or EQ if args permit;
15924 Otherwise return T. */
15926 {
15929 else
15931 }
15932 else
15938 }
15940 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15941 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15942 itself. */
15944 tree
15946 {
15947 /* If the expression does not have side effects then we don't have to wrap
15948 it with a cleanup point expression. */
15952 /* If the expression is a return, check to see if the expression inside the
15953 return has no side effects or the right hand side of the modify expression
15954 inside the return. If either don't have side effects set we don't need to
15955 wrap the expression in a cleanup point expression. Note we don't check the
15956 left hand side of the modify because it should always be a return decl. */
15958 {
15965 }
15968 }
15970 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15971 of an indirection through OP0, or NULL_TREE if no simplification is
15972 possible. */
15974 tree
15976 {
15978 tree subtype;
15986 {
15989 /* *&CONST_DECL -> to the value of the const decl. */
15992 /* *&p => p; make sure to handle *&"str"[cst] here. */
15994 {
15998 else
16000 }
16001 /* *(foo *)&fooarray => fooarray[0] */
16004 && (!in_gimple_form
16006 {
16016 }
16017 /* *(foo *)&complexfoo => __real__ complexfoo */
16021 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16024 {
16028 }
16029 }
16033 {
16039 {
16040 tree op00type;
16044 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16047 {
16059 }
16060 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16063 {
16067 }
16068 /* ((foo *)&fooarray)[1] => fooarray[1] */
16071 {
16081 }
16082 }
16083 }
16085 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16088 && (!in_gimple_form
16090 {
16091 tree type_domain;
16101 NULL_TREE);
16102 }
16105 }
16107 /* Builds an expression for an indirection through T, simplifying some
16108 cases. */
16110 tree
16112 {
16120 }
16122 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16124 tree
16126 {
16131 else
16133 }
16135 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16136 whose result is ignored. The type of the returned tree need not be
16137 the same as the original expression. */
16139 tree
16141 {
16147 {
16158 else
16164 {
16180 }
16185 }
16186 }
16188 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16190 tree
16192 {
16198 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16199 have to do anything. Only do this when we are not given a const,
16200 because in that case, this check is more expensive than just
16201 doing it. */
16203 {
16208 }
16210 /* If divisor is a power of two, simplify this to bit manipulation. */
16212 {
16214 {
16228 }
16229 else
16230 {
16231 tree t;
16237 }
16238 }
16239 else
16240 {
16245 }
16248 }
16250 /* Likewise, but round down. */
16252 tree
16254 {
16261 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16262 have to do anything. Only do this when we are not given a const,
16263 because in that case, this check is more expensive than just
16264 doing it. */
16266 {
16271 }
16273 /* If divisor is a power of two, simplify this to bit manipulation. */
16275 {
16276 tree t;
16280 }
16281 else
16282 {
16287 }
16290 }
16292 /* Returns the pointer to the base of the object addressed by EXP and
16293 extracts the information about the offset of the access, storing it
16294 to PBITPOS and POFFSET. */
16296 static tree
16299 {
16300 tree core;
16301 machine_mode mode;
16303 HOST_WIDE_INT bitsize;
16307 {
16312 }
16313 else
16314 {
16318 }
16321 }
16323 /* Returns true if addresses of E1 and E2 differ by a constant, false
16324 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16326 bool
16328 {
16342 {
16352 }
16354 {
16355 /* If only one of the offsets is non-constant, the difference cannot
16356 be a constant. */
16358 }
16359 else
16364 }
16366 /* Simplify the floating point expression EXP when the sign of the
16367 result is not significant. Return NULL_TREE if no simplification
16368 is possible. */
16370 tree
16372 {
16377 {
16413 {
16416 {
16418 /* Strip copysign function call, return the 1st argument. */
16424 /* Strip sign ops from the argument of "odd" math functions. */
16426 {
16430 }
16432 }
16433 }
16438 }
16440 }