| blob | 49ab04265a5c95a434f8f08e366b38fb3a2611c1 |
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. */
74 /* Nonzero if we are folding constants inside an initializer; zero
75 otherwise. */
78 /* The following constants represent a bit based encoding of GCC's
79 comparison operators. This encoding simplifies transformations
80 on relational comparison operators, such as AND and OR. */
98 };
118 HOST_WIDE_INT *,
149 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
150 Otherwise, return LOC. */
152 static location_t
154 {
157 }
159 /* Similar to protected_set_expr_location, but never modify x in place,
160 if location can and needs to be set, unshare it. */
164 {
170 {
173 }
175 }
176 \f
177 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
178 division and returns the quotient. Otherwise returns
179 NULL_TREE. */
181 tree
183 {
184 widest_int quo;
191 }
192 \f
193 /* This is nonzero if we should defer warnings about undefined
194 overflow. This facility exists because these warnings are a
195 special case. The code to estimate loop iterations does not want
196 to issue any warnings, since it works with expressions which do not
197 occur in user code. Various bits of cleanup code call fold(), but
198 only use the result if it has certain characteristics (e.g., is a
199 constant); that code only wants to issue a warning if the result is
200 used. */
204 /* If a warning about undefined overflow is deferred, this is the
205 warning. Note that this may cause us to turn two warnings into
206 one, but that is fine since it is sufficient to only give one
207 warning per expression. */
211 /* If a warning about undefined overflow is deferred, this is the
212 level at which the warning should be emitted. */
216 /* Start deferring overflow warnings. We could use a stack here to
217 permit nested calls, but at present it is not necessary. */
219 void
221 {
223 }
225 /* Stop deferring overflow warnings. If there is a pending warning,
226 and ISSUE is true, then issue the warning if appropriate. STMT is
227 the statement with which the warning should be associated (used for
228 location information); STMT may be NULL. CODE is the level of the
229 warning--a warn_strict_overflow_code value. This function will use
230 the smaller of CODE and the deferred code when deciding whether to
231 issue the warning. CODE may be zero to mean to always use the
232 deferred code. */
234 void
236 {
238 location_t locus;
243 {
249 }
260 /* Use the smallest code level when deciding to issue the
261 warning. */
270 else
273 }
275 /* Stop deferring overflow warnings, ignoring any deferred
276 warnings. */
278 void
280 {
282 }
284 /* Whether we are deferring overflow warnings. */
286 bool
288 {
290 }
292 /* This is called when we fold something based on the fact that signed
293 overflow is undefined. */
295 static void
297 {
299 {
302 {
305 }
306 }
309 }
310 \f
311 /* Return true if the built-in mathematical function specified by CODE
312 is odd, i.e. -f(x) == f(-x). */
314 static bool
316 {
318 {
352 }
354 }
356 /* Check whether we may negate an integer constant T without causing
357 overflow. */
359 bool
361 {
362 tree type;
371 }
373 /* Determine whether an expression T can be cheaply negated using
374 the function negate_expr without introducing undefined overflow. */
376 static bool
378 {
379 tree type;
388 {
393 /* Check that -CST will not overflow type. */
404 /* We want to canonicalize to positive real constants. Pretend
405 that only negative ones can be easily negated. */
413 {
424 }
437 /* -(A + B) -> (-B) - A. */
442 /* -(A + B) -> (-A) - B. */
446 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
456 /* Fall through. */
467 /* In general we can't negate A / B, because if A is INT_MIN and
468 B is 1, we may turn this into INT_MIN / -1 which is undefined
469 and actually traps on some architectures. But if overflow is
470 undefined, we can negate, because - (INT_MIN / 1) is an
471 overflow. */
473 {
476 /* If overflow is undefined then we have to be careful because
477 we ask whether it's ok to associate the negate with the
478 division which is not ok for example for
479 -((a - b) / c) where (-(a - b)) / c may invoke undefined
480 overflow because of negating INT_MIN. So do not use
481 negate_expr_p here but open-code the two important cases. */
486 }
492 /* Negate -((double)float) as (double)(-float). */
494 {
498 }
502 /* Negate -f(x) as f(-x). */
508 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
510 {
514 }
519 }
521 }
523 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
524 simplification is possible.
525 If negate_expr_p would return true for T, NULL_TREE will never be
526 returned. */
528 static tree
530 {
532 tree tem;
535 {
536 /* Convert - (~A) to A + 1. */
552 /* Two's complement FP formats, such as c4x, may overflow. */
562 {
571 }
575 {
580 {
584 }
587 }
608 {
609 /* -(A + B) -> (-B) - A. */
613 {
617 }
619 /* -(A + B) -> (-A) - B. */
621 {
625 }
626 }
630 /* - (A - B) -> B - A */
642 /* Fall through. */
646 {
655 }
661 /* In general we can't negate A / B, because if A is INT_MIN and
662 B is 1, we may turn this into INT_MIN / -1 which is undefined
663 and actually traps on some architectures. But if overflow is
664 undefined, we can negate, because - (INT_MIN / 1) is an
665 overflow. */
667 {
672 {
679 }
680 /* If overflow is undefined then we have to be careful because
681 we ask whether it's ok to associate the negate with the
682 division which is not ok for example for
683 -((a - b) / c) where (-(a - b)) / c may invoke undefined
684 overflow because of negating INT_MIN. So do not use
685 negate_expr_p here but open-code the two important cases. */
694 }
698 /* Convert -((double)float) into (double)(-float). */
700 {
704 }
708 /* Negate -f(x) as f(-x). */
711 {
717 }
721 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
723 {
726 {
733 }
734 }
739 }
742 }
744 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
745 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
746 return NULL_TREE. */
748 static tree
750 {
752 location_t loc;
765 }
766 \f
767 /* Split a tree IN into a constant, literal and variable parts that could be
768 combined with CODE to make IN. "constant" means an expression with
769 TREE_CONSTANT but that isn't an actual constant. CODE must be a
770 commutative arithmetic operation. Store the constant part into *CONP,
771 the literal in *LITP and return the variable part. If a part isn't
772 present, set it to null. If the tree does not decompose in this way,
773 return the entire tree as the variable part and the other parts as null.
775 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
776 case, we negate an operand that was subtracted. Except if it is a
777 literal for which we use *MINUS_LITP instead.
779 If NEGATE_P is true, we are negating all of IN, again except a literal
780 for which we use *MINUS_LITP instead.
782 If IN is itself a literal or constant, return it as appropriate.
784 Note that we do not guarantee that any of the three values will be the
785 same type as IN, but they will have the same signedness and mode. */
787 static tree
790 {
797 /* Strip any conversions that don't change the machine mode or signedness. */
806 /* We can associate addition and subtraction together (even
807 though the C standard doesn't say so) for integers because
808 the value is not affected. For reals, the value might be
809 affected, so we can't. */
812 {
818 /* First see if either of the operands is a literal, then a constant. */
831 /* If we haven't dealt with either operand, this is not a case we can
832 decompose. Otherwise, VAR is either of the ones remaining, if any. */
837 else
840 /* Now do any needed negations. */
847 }
850 {
851 /* -X - 1 is folded to ~X, undo that here. */
854 }
857 else
861 {
868 }
871 }
873 /* Re-associate trees split by the above function. T1 and T2 are
874 either expressions to associate or null. Return the new
875 expression, if any. LOC is the location of the new expression. If
876 we build an operation, do it in TYPE and with CODE. */
878 static tree
880 {
886 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
887 try to fold this since we will have infinite recursion. But do
888 deal with any NEGATE_EXPRs. */
891 {
893 {
906 }
908 {
911 }
915 }
919 }
920 \f
921 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
922 for use in int_const_binop, size_binop and size_diffop. */
924 static bool
926 {
933 {
942 }
947 }
950 /* Combine two integer constants ARG1 and ARG2 under operation CODE
951 to produce a new constant. Return NULL_TREE if we don't know how
952 to evaluate CODE at compile-time. */
954 static tree
957 {
958 wide_int res;
959 tree t;
968 {
984 {
988 else
990 }
993 /* It's unclear from the C standard whether shifts can overflow.
994 The following code ignores overflow; perhaps a C standard
995 interpretation ruling is needed. */
997 else
1004 {
1008 else
1010 }
1014 else
1093 }
1101 }
1103 tree
1105 {
1107 }
1109 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1110 constant. We assume ARG1 and ARG2 have the same data type, or at least
1111 are the same kind of constant and the same machine mode. Return zero if
1112 combining the constants is not allowed in the current operating mode. */
1114 static tree
1116 {
1117 /* Sanity check for the recursive cases. */
1128 {
1130 REAL_VALUE_TYPE d1;
1131 REAL_VALUE_TYPE d2;
1132 REAL_VALUE_TYPE value;
1133 REAL_VALUE_TYPE result;
1137 /* The following codes are handled by real_arithmetic. */
1139 {
1150 }
1158 /* Don't perform operation if we honor signaling NaNs and
1159 either operand is a NaN. */
1164 /* Don't perform operation if it would raise a division
1165 by zero exception. */
1171 /* If either operand is a NaN, just return it. Otherwise, set up
1172 for floating-point trap; we return an overflow. */
1181 /* Don't constant fold this floating point operation if
1182 the result has overflowed and flag_trapping_math. */
1190 /* Don't constant fold this floating point operation if the
1191 result may dependent upon the run-time rounding mode and
1192 flag_rounding_math is set, or if GCC's software emulation
1193 is unable to accurately represent the result. */
1203 }
1206 {
1207 FIXED_VALUE_TYPE f1;
1208 FIXED_VALUE_TYPE f2;
1209 FIXED_VALUE_TYPE result;
1214 /* The following codes are handled by fixed_arithmetic. */
1216 {
1226 {
1231 }
1236 }
1243 /* Propagate overflow flags. */
1247 }
1250 {
1259 {
1270 mpc_mul);
1284 mpc_div);
1285 /* Fallthru ... */
1291 {
1292 /* Keep this algorithm in sync with
1293 tree-complex.c:expand_complex_div_straight().
1295 Expand complex division to scalars, straightforward algorithm.
1296 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1297 t = br*br + bi*bi
1298 */
1299 tree magsquared
1303 tree t1
1307 tree t2
1314 }
1315 else
1316 {
1317 /* Keep this algorithm in sync with
1318 tree-complex.c:expand_complex_div_wide().
1320 Expand complex division to scalars, modified algorithm to minimize
1321 overflow with wide input ranges. */
1327 {
1328 /* In the TRUE branch, we compute
1329 ratio = br/bi;
1330 div = (br * ratio) + bi;
1331 tr = (ar * ratio) + ai;
1332 ti = (ai * ratio) - ar;
1333 tr = tr / div;
1334 ti = ti / div; */
1345 }
1346 else
1347 {
1348 /* In the FALSE branch, we compute
1349 ratio = d/c;
1350 divisor = (d * ratio) + c;
1351 tr = (b * ratio) + a;
1352 ti = b - (a * ratio);
1353 tr = tr / div;
1354 ti = ti / div; */
1366 }
1367 }
1372 }
1376 }
1380 {
1386 {
1392 /* It is possible that const_binop cannot handle the given
1393 code and return NULL_TREE */
1396 }
1399 }
1401 /* Shifts allow a scalar offset for a vector. */
1404 {
1411 {
1417 unsigned HOST_WIDE_INT innerc
1422 /* The direction of VEC_[LR]SHIFT_EXPR is endian dependent.
1423 For reductions, compiler emits VEC_RSHIFT_EXPR always,
1424 for !BYTES_BIG_ENDIAN picks first vector element, but
1425 for BYTES_BIG_ENDIAN last element from the vector. */
1430 {
1433 else
1435 }
1436 }
1437 else
1439 {
1444 /* It is possible that const_binop cannot handle the given
1445 code and return NULL_TREE */
1448 }
1451 }
1453 }
1455 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1456 indicates which particular sizetype to create. */
1458 tree
1460 {
1462 }
1463 \f
1464 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1465 is a tree code. The type of the result is taken from the operands.
1466 Both must be equivalent integer types, ala int_binop_types_match_p.
1467 If the operands are constant, so is the result. */
1469 tree
1471 {
1480 /* Handle the special case of two integer constants faster. */
1482 {
1483 /* And some specific cases even faster than that. */
1485 {
1490 }
1492 {
1495 }
1497 {
1500 }
1502 /* Handle general case of two integer constants. For sizetype
1503 constant calculations we always want to know about overflow,
1504 even in the unsigned case. */
1506 }
1509 }
1511 /* Given two values, either both of sizetype or both of bitsizetype,
1512 compute the difference between the two values. Return the value
1513 in signed type corresponding to the type of the operands. */
1515 tree
1517 {
1519 tree ctype;
1524 /* If the type is already signed, just do the simple thing. */
1532 else
1535 /* If either operand is not a constant, do the conversions to the signed
1536 type and subtract. The hardware will do the right thing with any
1537 overflow in the subtraction. */
1543 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1544 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1545 overflow) and negate (which can't either). Special-case a result
1546 of zero while we're here. */
1552 else
1556 MINUS_EXPR,
1558 }
1559 \f
1560 /* A subroutine of fold_convert_const handling conversions of an
1561 INTEGER_CST to another integer type. */
1563 static tree
1565 {
1566 /* Given an integer constant, make new constant with new type,
1567 appropriately sign-extended or truncated. Use widest_int
1568 so that any extension is done according ARG1's type. */
1572 }
1574 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1575 to an integer type. */
1577 static tree
1579 {
1581 tree t;
1583 /* The following code implements the floating point to integer
1584 conversion rules required by the Java Language Specification,
1585 that IEEE NaNs are mapped to zero and values that overflow
1586 the target precision saturate, i.e. values greater than
1587 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1588 are mapped to INT_MIN. These semantics are allowed by the
1589 C and C++ standards that simply state that the behavior of
1590 FP-to-integer conversion is unspecified upon overflow. */
1592 wide_int val;
1593 REAL_VALUE_TYPE r;
1597 {
1604 }
1606 /* If R is NaN, return zero and show we have an overflow. */
1608 {
1611 }
1613 /* See if R is less than the lower bound or greater than the
1614 upper bound. */
1617 {
1621 {
1624 }
1625 }
1628 {
1631 {
1634 {
1637 }
1638 }
1639 }
1646 }
1648 /* A subroutine of fold_convert_const handling conversions of a
1649 FIXED_CST to an integer type. */
1651 static tree
1653 {
1654 tree t;
1658 /* Right shift FIXED_CST to temp by fbit. */
1662 {
1664 HOST_BITS_PER_DOUBLE_INT,
1667 /* Left shift temp to temp_trunc by fbit. */
1669 HOST_BITS_PER_DOUBLE_INT,
1671 }
1672 else
1673 {
1676 }
1678 /* If FIXED_CST is negative, we need to round the value toward 0.
1679 By checking if the fractional bits are not zero to add 1 to temp. */
1685 /* Given a fixed-point constant, make new constant with new type,
1686 appropriately sign-extended or truncated. */
1694 }
1696 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1697 to another floating point type. */
1699 static tree
1701 {
1702 REAL_VALUE_TYPE value;
1703 tree t;
1708 /* If converting an infinity or NAN to a representation that doesn't
1709 have one, set the overflow bit so that we can produce some kind of
1710 error message at the appropriate point if necessary. It's not the
1711 most user-friendly message, but it's better than nothing. */
1718 /* Regular overflow, conversion produced an infinity in a mode that
1719 can't represent them. */
1724 else
1727 }
1729 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1730 to a floating point type. */
1732 static tree
1734 {
1735 REAL_VALUE_TYPE value;
1736 tree t;
1743 }
1745 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1746 to another fixed-point type. */
1748 static tree
1750 {
1751 FIXED_VALUE_TYPE value;
1752 tree t;
1759 /* Propagate overflow flags. */
1763 }
1765 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
1766 to a fixed-point type. */
1768 static tree
1770 {
1771 FIXED_VALUE_TYPE value;
1772 tree t;
1774 double_int di;
1781 else
1789 /* Propagate overflow flags. */
1793 }
1795 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1796 to a fixed-point type. */
1798 static tree
1800 {
1801 FIXED_VALUE_TYPE value;
1802 tree t;
1810 /* Propagate overflow flags. */
1814 }
1816 /* Attempt to fold type conversion operation CODE of expression ARG1 to
1817 type TYPE. If no simplification can be done return NULL_TREE. */
1819 static tree
1821 {
1827 {
1834 }
1836 {
1843 }
1845 {
1852 }
1854 }
1856 /* Construct a vector of zero elements of vector type TYPE. */
1858 static tree
1860 {
1861 tree t;
1865 }
1867 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
1869 bool
1871 {
1886 {
1905 }
1906 }
1908 /* Convert expression ARG to type TYPE. Used by the middle-end for
1909 simple conversions in preference to calling the front-end's convert. */
1911 tree
1913 {
1915 tree tem;
1926 {
1929 /* Handle conversions between pointers to different address spaces. */
1934 /* fall through */
1939 {
1943 }
1957 {
1961 }
1963 {
1967 }
1969 {
1973 }
1976 {
1994 }
1999 {
2003 }
2006 {
2020 }
2024 {
2033 integer_zero_node));
2035 {
2039 {
2045 }
2053 }
2057 }
2075 }
2076 fold_convert_exit:
2079 }
2080 \f
2081 /* Return false if expr can be assumed not to be an lvalue, true
2082 otherwise. */
2084 static bool
2086 {
2087 /* We only need to wrap lvalue tree codes. */
2089 {
2120 /* Assume the worst for front-end tree codes. */
2124 }
2127 }
2129 /* Return an expr equal to X but certainly not valid as an lvalue. */
2131 tree
2133 {
2134 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2135 us. */
2142 }
2144 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2145 Zero means allow extended lvalues. */
2149 /* When pedantic, return an expr equal to X but certainly not valid as a
2150 pedantic lvalue. Otherwise, return X. */
2152 static tree
2154 {
2159 }
2160 \f
2161 /* Given a tree comparison code, return the code that is the logical inverse.
2162 It is generally not safe to do this for floating-point comparisons, except
2163 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2164 ERROR_MARK in this case. */
2166 enum tree_code
2168 {
2174 {
2205 }
2206 }
2208 /* Similar, but return the comparison that results if the operands are
2209 swapped. This is safe for floating-point. */
2211 enum tree_code
2213 {
2215 {
2241 }
2242 }
2245 /* Convert a comparison tree code from an enum tree_code representation
2246 into a compcode bit-based encoding. This function is the inverse of
2247 compcode_to_comparison. */
2249 static enum comparison_code
2251 {
2253 {
2284 }
2285 }
2287 /* Convert a compcode bit-based encoding of a comparison operator back
2288 to GCC's enum tree_code representation. This function is the
2289 inverse of comparison_to_compcode. */
2291 static enum tree_code
2293 {
2295 {
2326 }
2327 }
2329 /* Return a tree for the comparison which is the combination of
2330 doing the AND or OR (depending on CODE) of the two operations LCODE
2331 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2332 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2333 if this makes the transformation invalid. */
2335 tree
2340 {
2347 {
2358 }
2361 {
2362 /* Eliminate unordered comparisons, as well as LTGT and ORD
2363 which are not used unless the mode has NaNs. */
2369 }
2371 {
2372 /* Check that the original operation and the optimized ones will trap
2373 under the same condition. */
2384 /* In a short-circuited boolean expression the LHS might be
2385 such that the RHS, if evaluated, will never trap. For
2386 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2387 if neither x nor y is NaN. (This is a mixed blessing: for
2388 example, the expression above will never trap, hence
2389 optimizing it to x < y would be invalid). */
2394 /* If the comparison was short-circuited, and only the RHS
2395 trapped, we may now generate a spurious trap. */
2400 /* If we changed the conditions that cause a trap, we lose. */
2403 }
2409 else
2410 {
2415 }
2416 }
2417 \f
2418 /* Return nonzero if two operands (typically of the same tree node)
2419 are necessarily equal. If either argument has side-effects this
2420 function returns zero. FLAGS modifies behavior as follows:
2422 If OEP_ONLY_CONST is set, only return nonzero for constants.
2423 This function tests whether the operands are indistinguishable;
2424 it does not test whether they are equal using C's == operation.
2425 The distinction is important for IEEE floating point, because
2426 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2427 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2429 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2430 even though it may hold multiple values during a function.
2431 This is because a GCC tree node guarantees that nothing else is
2432 executed between the evaluation of its "operands" (which may often
2433 be evaluated in arbitrary order). Hence if the operands themselves
2434 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2435 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2436 unset means assuming isochronic (or instantaneous) tree equivalence.
2437 Unless comparing arbitrary expression trees, such as from different
2438 statements, this flag can usually be left unset.
2440 If OEP_PURE_SAME is set, then pure functions with identical arguments
2441 are considered the same. It is used when the caller has other ways
2442 to ensure that global memory is unchanged in between.
2444 If OEP_ALLOW_NULL is set, this routine will not crash on NULL operands,
2445 and two NULL operands are considered equal. This flag is usually set
2446 in the context of frontend when ARG0 and/or ARG1 may be NULL mostly due
2447 to recursion on partially built expressions (e.g. a CAST_EXPR on a NULL
2448 tree.) In this case, we certainly don't want the compiler to crash and
2449 it's OK to consider two NULL operands equal. On the other hand, when
2450 called in the context of code generation and optimization, if NULL
2451 operands are not expected, silently ignoring them could be dangerous
2452 and might cause problems downstream that are hard to find/debug. In that
2453 case, the flag should probably not be set. */
2455 int
2457 {
2458 /* If either is NULL, they must be both NULL to be equal. We only do this
2459 check when OEP_ALLOW_NULL is set. */
2463 /* If either is ERROR_MARK, they aren't equal. */
2469 /* Similar, if either does not have a type (like a released SSA name),
2470 they aren't equal. */
2472 {
2473 /* If the caller chooses to allow the comparison of operands without
2474 types, we will continue the comparison only when both of them don't
2475 have a type. */
2478 }
2480 /* Check equality of integer constants before bailing out due to
2481 precision differences. */
2485 /* If both types don't have the same signedness, then we can't consider
2486 them equal. We must check this before the STRIP_NOPS calls
2487 because they may change the signedness of the arguments. As pointers
2488 strictly don't have a signedness, require either two pointers or
2489 two non-pointers as well. */
2496 /* We cannot consider pointers to different address space equal. */
2503 /* If both types don't have the same precision, then it is not safe
2504 to strip NOPs. */
2512 /* In case both args are comparisons but with different comparison
2513 code, try to swap the comparison operands of one arg to produce
2514 a match and compare that variant. */
2518 {
2526 }
2529 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2533 /* This is needed for conversions and for COMPONENT_REF.
2534 Might as well play it safe and always test this. */
2540 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2541 We don't care about side effects in that case because the SAVE_EXPR
2542 takes care of that for us. In all other cases, two expressions are
2543 equal if they have no side effects. If we have two identical
2544 expressions with side effects that should be treated the same due
2545 to the only side effects being identical SAVE_EXPR's, that will
2546 be detected in the recursive calls below.
2547 If we are taking an invariant address of two identical objects
2548 they are necessarily equal as well. */
2555 /* Next handle constant cases, those for which we can return 1 even
2556 if ONLY_CONST is set. */
2559 {
2575 {
2576 /* If we do not distinguish between signed and unsigned zero,
2577 consider them equal. */
2580 }
2584 {
2591 {
2595 }
2597 }
2601 flags)
2603 flags));
2617 }
2622 /* Define macros to test an operand from arg0 and arg1 for equality and a
2623 variant that allows null and views null as being different from any
2624 non-null value. In the latter case, if either is null, the both
2625 must be; otherwise, do the normal comparison. */
2626 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2627 TREE_OPERAND (arg1, N), flags)
2629 #define OP_SAME_WITH_NULL(N) \
2630 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2631 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2634 {
2636 /* Two conversions are equal only if signedness and modes match. */
2638 {
2639 CASE_CONVERT:
2648 }
2658 /* For commutative ops, allow the other order. */
2666 /* If either of the pointer (or reference) expressions we are
2667 dereferencing contain a side effect, these cannot be equal,
2668 but their addresses can be. */
2675 {
2686 /* Require equal extra operands and then fall through to MEM_REF
2687 handling of the two common operands. */
2692 /* Fallthru. */
2695 /* Require equal access sizes, and similar pointer types.
2696 We can have incomplete types for array references of
2697 variable-sized arrays from the Fortran frontend
2698 though. Also verify the types are compatible. */
2706 flags)))
2708 && alias_ptr_types_compatible_p
2715 /* Operands 2 and 3 may be null.
2716 Compare the array index by value if it is constant first as we
2717 may have different types but same value here. */
2728 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2729 may be NULL when we're called to compare MEM_EXPRs. */
2744 }
2748 {
2762 /* The multiplcation operands are commutative. */
2763 /* FALLTHRU */
2771 /* Otherwise take into account this is a commutative operation. */
2784 }
2788 {
2790 /* If the CALL_EXPRs call different functions, then they
2791 clearly can not be equal. */
2793 flags))
2796 {
2800 else
2804 }
2806 /* Now see if all the arguments are the same. */
2807 {
2818 /* If we get here and both argument lists are exhausted
2819 then the CALL_EXPRs are equal. */
2821 }
2824 }
2827 /* Consider __builtin_sqrt equal to sqrt. */
2835 }
2837 #undef OP_SAME
2838 #undef OP_SAME_WITH_NULL
2839 }
2840 \f
2841 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2842 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2844 When in doubt, return 0. */
2846 static int
2848 {
2860 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2861 and see if the inner values are the same. This removes any
2862 signedness comparison, which doesn't matter here. */
2869 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2870 actual comparison operand, ARG0.
2872 First throw away any conversions to wider types
2873 already present in the operands. */
2882 {
2885 /* Make sure shorter operand is extended the right way
2886 to match the longer operand. */
2892 }
2895 }
2896 \f
2897 /* See if ARG is an expression that is either a comparison or is performing
2898 arithmetic on comparisons. The comparisons must only be comparing
2899 two different values, which will be stored in *CVAL1 and *CVAL2; if
2900 they are nonzero it means that some operands have already been found.
2901 No variables may be used anywhere else in the expression except in the
2902 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2903 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2905 If this is true, return 1. Otherwise, return zero. */
2907 static int
2909 {
2913 /* We can handle some of the tcc_expression cases here. */
2923 {
2924 /* If we've already found a CVAL1 or CVAL2, this expression is
2925 two complex to handle. */
2931 }
2934 {
2957 /* First see if we can handle the first operand, then the second. For
2958 the second operand, we know *CVAL1 can't be zero. It must be that
2959 one side of the comparison is each of the values; test for the
2960 case where this isn't true by failing if the two operands
2961 are the same. */
2970 ;
2974 ;
2975 else
2979 ;
2983 ;
2984 else
2991 }
2992 }
2993 \f
2994 /* ARG is a tree that is known to contain just arithmetic operations and
2995 comparisons. Evaluate the operations in the tree substituting NEW0 for
2996 any occurrence of OLD0 as an operand of a comparison and likewise for
2997 NEW1 and OLD1. */
2999 static tree
3002 {
3007 /* We can handle some of the tcc_expression cases here. */
3015 {
3030 {
3049 }
3050 /* Fall through - ??? */
3053 {
3057 /* We need to check both for exact equality and tree equality. The
3058 former will be true if the operand has a side-effect. In that
3059 case, we know the operand occurred exactly once. */
3072 }
3076 }
3077 }
3078 \f
3079 /* Return a tree for the case when the result of an expression is RESULT
3080 converted to TYPE and OMITTED was previously an operand of the expression
3081 but is now not needed (e.g., we folded OMITTED * 0).
3083 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3084 the conversion of RESULT to TYPE. */
3086 tree
3088 {
3091 /* If the resulting operand is an empty statement, just return the omitted
3092 statement casted to void. */
3102 }
3104 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3106 static tree
3108 tree omitted)
3109 {
3112 /* If the resulting operand is an empty statement, just return the omitted
3113 statement casted to void. */
3123 }
3125 /* Return a tree for the case when the result of an expression is RESULT
3126 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3127 of the expression but are now not needed.
3129 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3130 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3131 evaluated before OMITTED2. Otherwise, if neither has side effects,
3132 just do the conversion of RESULT to TYPE. */
3134 tree
3137 {
3146 }
3148 \f
3149 /* Return a simplified tree node for the truth-negation of ARG. This
3150 never alters ARG itself. We assume that ARG is an operation that
3151 returns a truth value (0 or 1).
3153 FIXME: one would think we would fold the result, but it causes
3154 problems with the dominator optimizer. */
3156 static tree
3158 {
3163 /* If this is a comparison, we can simply invert it, except for
3164 floating-point non-equality comparisons, in which case we just
3165 enclose a TRUTH_NOT_EXPR around what we have. */
3168 {
3171 && flag_trapping_math
3182 }
3185 {
3204 /* Here we can invert either operand. We invert the first operand
3205 unless the second operand is a TRUTH_NOT_EXPR in which case our
3206 result is the XOR of the first operand with the inside of the
3207 negation of the second operand. */
3212 else
3235 {
3242 /* A COND_EXPR may have a throw as one operand, which
3243 then has void type. Just leave void operands
3244 as they are. */
3250 }
3262 CASE_CONVERT:
3266 /* ... fall through ... */
3288 }
3289 }
3291 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3292 assume that ARG is an operation that returns a truth value (0 or 1
3293 for scalars, 0 or -1 for vectors). Return the folded expression if
3294 folding is successful. Otherwise, return NULL_TREE. */
3296 static tree
3298 {
3301 ? BIT_NOT_EXPR
3304 }
3306 /* Return a simplified tree node for the truth-negation of ARG. This
3307 never alters ARG itself. We assume that ARG is an operation that
3308 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3310 tree
3312 {
3318 ? BIT_NOT_EXPR
3321 }
3323 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3324 operands are another bit-wise operation with a common input. If so,
3325 distribute the bit operations to save an operation and possibly two if
3326 constants are involved. For example, convert
3327 (A | B) & (A | C) into A | (B & C)
3328 Further simplification will occur if B and C are constants.
3330 If this optimization cannot be done, 0 will be returned. */
3332 static tree
3335 {
3336 tree common;
3346 {
3350 }
3352 {
3356 }
3358 {
3362 }
3364 {
3368 }
3369 else
3377 }
3379 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3380 with code CODE. This optimization is unsafe. */
3381 static tree
3384 {
3388 /* (A / C) +- (B / C) -> (A +- B) / C. */
3398 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3403 {
3415 }
3418 }
3419 \f
3420 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3421 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3423 static tree
3426 {
3430 {
3437 }
3451 }
3453 /* Optimize a bit-field compare.
3455 There are two cases: First is a compare against a constant and the
3456 second is a comparison of two items where the fields are at the same
3457 bit position relative to the start of a chunk (byte, halfword, word)
3458 large enough to contain it. In these cases we can avoid the shift
3459 implicit in bitfield extractions.
3461 For constants, we emit a compare of the shifted constant with the
3462 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3463 compared. For two fields at the same position, we do the ANDs with the
3464 similar mask and compare the result of the ANDs.
3466 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3467 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3468 are the left and right operands of the comparison, respectively.
3470 If the optimization described above can be done, we return the resulting
3471 tree. Otherwise we return zero. */
3473 static tree
3476 {
3479 tree unsigned_type;
3485 tree mask;
3486 tree offset;
3488 /* Get all the information about the extractions being done. If the bit size
3489 if the same as the size of the underlying object, we aren't doing an
3490 extraction at all and so can do nothing. We also don't want to
3491 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3492 then will no longer be able to replace it. */
3500 {
3501 /* If this is not a constant, we can only do something if bit positions,
3502 sizes, and signedness are the same. */
3510 }
3512 /* See if we can find a mode to refer to this field. We should be able to,
3513 but fail if we can't. */
3522 /* Set signed and unsigned types of the precision of this mode for the
3523 shifts below. */
3526 /* Compute the bit position and size for the new reference and our offset
3527 within it. If the new reference is the same size as the original, we
3528 won't optimize anything, so return zero. */
3538 /* Make the mask to be used against the extracted field. */
3545 /* If not comparing with constant, just rework the comparison
3546 and return. */
3550 unsigned_type,
3553 mask),
3556 unsigned_type,
3559 mask));
3561 /* Otherwise, we are handling the constant case. See if the constant is too
3562 big for the field. Warn and return a tree of for 0 (false) if so. We do
3563 this not only for its own sake, but to avoid having to test for this
3564 error case below. If we didn't, we might generate wrong code.
3566 For unsigned fields, the constant shifted right by the field length should
3567 be all zero. For signed fields, the high-order bits should agree with
3568 the sign bit. */
3571 {
3573 {
3577 }
3578 }
3579 else
3580 {
3583 {
3587 }
3588 }
3590 /* Single-bit compares should always be against zero. */
3592 {
3595 }
3597 /* Make a new bitfield reference, shift the constant over the
3598 appropriate number of bits and mask it with the computed mask
3599 (in case this was a signed field). If we changed it, make a new one. */
3606 mask);
3611 }
3612 \f
3613 /* Subroutine for fold_truth_andor_1: decode a field reference.
3615 If EXP is a comparison reference, we return the innermost reference.
3617 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3618 set to the starting bit number.
3620 If the innermost field can be completely contained in a mode-sized
3621 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3623 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3624 otherwise it is not changed.
3626 *PUNSIGNEDP is set to the signedness of the field.
3628 *PMASK is set to the mask used. This is either contained in a
3629 BIT_AND_EXPR or derived from the width of the field.
3631 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3633 Return 0 if this is not a component reference or is one that we can't
3634 do anything with. */
3636 static tree
3641 {
3645 tree unsigned_type;
3648 /* All the optimizations using this function assume integer fields.
3649 There are problems with FP fields since the type_for_size call
3650 below can fail for, e.g., XFmode. */
3654 /* We are interested in the bare arrangement of bits, so strip everything
3655 that doesn't affect the machine mode. However, record the type of the
3656 outermost expression if it may matter below. */
3663 {
3669 }
3678 /* If the number of bits in the reference is the same as the bitsize of
3679 the outer type, then the outer type gives the signedness. Otherwise
3680 (in case of a small bitfield) the signedness is unchanged. */
3684 /* Compute the mask to access the bitfield. */
3693 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3701 }
3703 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3704 bit positions and MASK is SIGNED. */
3706 static int
3708 {
3712 /* If this function returns true when the type of the mask is
3713 UNSIGNED, then there will be errors. In particular see
3714 gcc.c-torture/execute/990326-1.c. There does not appear to be
3715 any documentation paper trail as to why this is so. But the pre
3716 wide-int worked with that restriction and it has been preserved
3717 here. */
3722 }
3724 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3725 represents the sign bit of EXP's type. If EXP represents a sign
3726 or zero extension, also test VAL against the unextended type.
3727 The return value is the (sub)expression whose sign bit is VAL,
3728 or NULL_TREE otherwise. */
3730 static tree
3732 {
3734 tree t;
3736 /* Tree EXP must have an integral type. */
3741 /* Tree VAL must be an integer constant. */
3750 /* Handle extension from a narrower type. */
3756 }
3758 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3759 to be evaluated unconditionally. */
3761 static int
3763 {
3764 /* Strip any conversions that don't change the machine mode. */
3773 /* Don't regard global variables as simple. They may be
3774 allocated in ways unknown to the compiler (shared memory,
3775 #pragma weak, etc). */
3778 /* Weakrefs are not safe to be read, since they can be NULL.
3779 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3780 have DECL_WEAK flag set. */
3782 /* Loading a static variable is unduly expensive, but global
3783 registers aren't expensive. */
3785 }
3787 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3788 to be evaluated unconditionally.
3789 I addition to simple_operand_p, we assume that comparisons, conversions,
3790 and logic-not operations are simple, if their operands are simple, too. */
3792 static bool
3794 {
3814 }
3816 \f
3817 /* The following functions are subroutines to fold_range_test and allow it to
3818 try to change a logical combination of comparisons into a range test.
3820 For example, both
3821 X == 2 || X == 3 || X == 4 || X == 5
3822 and
3823 X >= 2 && X <= 5
3824 are converted to
3825 (unsigned) (X - 2) <= 3
3827 We describe each set of comparisons as being either inside or outside
3828 a range, using a variable named like IN_P, and then describe the
3829 range with a lower and upper bound. If one of the bounds is omitted,
3830 it represents either the highest or lowest value of the type.
3832 In the comments below, we represent a range by two numbers in brackets
3833 preceded by a "+" to designate being inside that range, or a "-" to
3834 designate being outside that range, so the condition can be inverted by
3835 flipping the prefix. An omitted bound is represented by a "-". For
3836 example, "- [-, 10]" means being outside the range starting at the lowest
3837 possible value and ending at 10, in other words, being greater than 10.
3838 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3839 always false.
3841 We set up things so that the missing bounds are handled in a consistent
3842 manner so neither a missing bound nor "true" and "false" need to be
3843 handled using a special case. */
3845 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3846 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3847 and UPPER1_P are nonzero if the respective argument is an upper bound
3848 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3849 must be specified for a comparison. ARG1 will be converted to ARG0's
3850 type if both are specified. */
3852 static tree
3855 {
3856 tree tem;
3860 /* If neither arg represents infinity, do the normal operation.
3861 Else, if not a comparison, return infinity. Else handle the special
3862 comparison rules. Note that most of the cases below won't occur, but
3863 are handled for consistency. */
3866 {
3871 }
3876 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3877 for neither. In real maths, we cannot assume open ended ranges are
3878 the same. But, this is computer arithmetic, where numbers are finite.
3879 We can therefore make the transformation of any unbounded range with
3880 the value Z, Z being greater than any representable number. This permits
3881 us to treat unbounded ranges as equal. */
3885 {
3906 }
3909 }
3910 \f
3911 /* Helper routine for make_range. Perform one step for it, return
3912 new expression if the loop should continue or NULL_TREE if it should
3913 stop. */
3915 tree
3919 {
3925 {
3927 /* We can only do something if the range is testing for zero. */
3936 /* We can only do something if the range is testing for zero
3937 and if the second operand is an integer constant. Note that
3938 saying something is "in" the range we make is done by
3939 complementing IN_P since it will set in the initial case of
3940 being not equal to zero; "out" is leaving it alone. */
3947 {
3968 }
3970 /* If this is an unsigned comparison, we also know that EXP is
3971 greater than or equal to zero. We base the range tests we make
3972 on that fact, so we record it here so we can parse existing
3973 range tests. We test arg0_type since often the return type
3974 of, e.g. EQ_EXPR, is boolean. */
3976 {
3980 NULL_TREE))
3985 /* If the high bound is missing, but we have a nonzero low
3986 bound, reverse the range so it goes from zero to the low bound
3987 minus 1. */
3989 {
3994 }
3995 }
4003 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4004 low and high are non-NULL, then normalize will DTRT. */
4007 {
4012 }
4014 /* (-x) IN [a,b] -> x in [-b, -a] */
4026 /* ~ X -> -X - 1 */
4035 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4036 move a constant to the other side. */
4041 /* If EXP is signed, any overflow in the computation is undefined,
4042 so we don't worry about it so long as our computations on
4043 the bounds don't overflow. For unsigned, overflow is defined
4044 and this is exactly the right thing. */
4056 normalize:
4057 /* Check for an unsigned range which has wrapped around the maximum
4058 value thus making n_high < n_low, and normalize it. */
4060 {
4066 /* If the range is of the form +/- [ x+1, x ], we won't
4067 be able to normalize it. But then, it represents the
4068 whole range or the empty set, so make it
4069 +/- [ -, - ]. */
4073 else
4075 }
4076 else
4084 CASE_CONVERT:
4102 /* If we're converting arg0 from an unsigned type, to exp,
4103 a signed type, we will be doing the comparison as unsigned.
4104 The tests above have already verified that LOW and HIGH
4105 are both positive.
4107 So we have to ensure that we will handle large unsigned
4108 values the same way that the current signed bounds treat
4109 negative values. */
4112 {
4113 tree high_positive;
4114 tree equiv_type;
4115 /* For fixed-point modes, we need to pass the saturating flag
4116 as the 2nd parameter. */
4118 equiv_type
4121 else
4122 equiv_type
4125 /* A range without an upper bound is, naturally, unbounded.
4126 Since convert would have cropped a very large value, use
4127 the max value for the destination type. */
4128 high_positive
4135 high_positive),
4138 /* If the low bound is specified, "and" the range with the
4139 range for which the original unsigned value will be
4140 positive. */
4142 {
4145 integer_zero_node),
4146 high_positive))
4150 }
4151 else
4152 {
4153 /* Otherwise, "or" the range with the range of the input
4154 that will be interpreted as negative. */
4157 integer_zero_node),
4158 high_positive))
4162 }
4163 }
4172 }
4173 }
4175 /* Given EXP, a logical expression, set the range it is testing into
4176 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4177 actually being tested. *PLOW and *PHIGH will be made of the same
4178 type as the returned expression. If EXP is not a comparison, we
4179 will most likely not be returning a useful value and range. Set
4180 *STRICT_OVERFLOW_P to true if the return value is only valid
4181 because signed overflow is undefined; otherwise, do not change
4182 *STRICT_OVERFLOW_P. */
4184 tree
4187 {
4195 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4196 and see if we can refine the range. Some of the cases below may not
4197 happen, but it doesn't seem worth worrying about this. We "continue"
4198 the outer loop when we've changed something; otherwise we "break"
4199 the switch, which will "break" the while. */
4205 {
4211 {
4219 }
4228 }
4230 /* If EXP is a constant, we can evaluate whether this is true or false. */
4232 {
4239 }
4243 }
4244 \f
4245 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4246 type, TYPE, return an expression to test if EXP is in (or out of, depending
4247 on IN_P) the range. Return 0 if the test couldn't be created. */
4249 tree
4252 {
4255 #ifdef HAVE_canonicalize_funcptr_for_compare
4256 /* Disable this optimization for function pointer expressions
4257 on targets that require function pointer canonicalization. */
4262 #endif
4265 {
4271 }
4289 {
4291 {
4295 }
4297 }
4299 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4301 {
4305 {
4307 {
4310 etype
4312 else
4315 }
4318 }
4319 }
4321 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4322 This requires wrap-around arithmetics for the type of the expression.
4323 First make sure that arithmetics in this type is valid, then make sure
4324 that it wraps around. */
4330 {
4333 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4334 for the type in question, as we rely on this here. */
4344 else
4346 }
4356 {
4358 {
4363 }
4365 }
4373 }
4374 \f
4375 /* Return the predecessor of VAL in its type, handling the infinite case. */
4377 static tree
4379 {
4385 else
4388 }
4390 /* Return the successor of VAL in its type, handling the infinite case. */
4392 static tree
4394 {
4400 else
4403 }
4405 /* Given two ranges, see if we can merge them into one. Return 1 if we
4406 can, 0 if we can't. Set the output range into the specified parameters. */
4408 bool
4411 {
4415 tree tem;
4425 /* Make range 0 be the range that starts first, or ends last if they
4426 start at the same value. Swap them if it isn't. */
4429 || (lowequal
4432 {
4436 }
4438 /* Now flag two cases, whether the ranges are disjoint or whether the
4439 second range is totally subsumed in the first. Note that the tests
4440 below are simplified by the ones above. */
4446 /* We now have four cases, depending on whether we are including or
4447 excluding the two ranges. */
4449 {
4450 /* If they don't overlap, the result is false. If the second range
4451 is a subset it is the result. Otherwise, the range is from the start
4452 of the second to the end of the first. */
4457 else
4459 }
4462 {
4463 /* If they don't overlap, the result is the first range. If they are
4464 equal, the result is false. If the second range is a subset of the
4465 first, and the ranges begin at the same place, we go from just after
4466 the end of the second range to the end of the first. If the second
4467 range is not a subset of the first, or if it is a subset and both
4468 ranges end at the same place, the range starts at the start of the
4469 first range and ends just before the second range.
4470 Otherwise, we can't describe this as a single range. */
4476 {
4481 {
4482 /* We are in the weird situation where high0 > high1 but
4483 high1 has no successor. Punt. */
4485 }
4486 }
4488 {
4493 {
4494 /* low0 < low1 but low1 has no predecessor. Punt. */
4496 }
4497 }
4498 else
4500 }
4503 {
4504 /* If they don't overlap, the result is the second range. If the second
4505 is a subset of the first, the result is false. Otherwise,
4506 the range starts just after the first range and ends at the
4507 end of the second. */
4512 else
4513 {
4518 {
4519 /* high1 > high0 but high0 has no successor. Punt. */
4521 }
4522 }
4523 }
4525 else
4526 {
4527 /* The case where we are excluding both ranges. Here the complex case
4528 is if they don't overlap. In that case, the only time we have a
4529 range is if they are adjacent. If the second is a subset of the
4530 first, the result is the first. Otherwise, the range to exclude
4531 starts at the beginning of the first range and ends at the end of the
4532 second. */
4534 {
4539 else
4540 {
4541 /* Canonicalize - [min, x] into - [-, x]. */
4544 {
4549 /* FALLTHROUGH */
4562 }
4564 /* Canonicalize - [x, max] into - [x, -]. */
4567 {
4572 /* FALLTHROUGH */
4588 }
4590 /* The ranges might be also adjacent between the maximum and
4591 minimum values of the given type. For
4592 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4593 return + [x + 1, y - 1]. */
4595 {
4602 }
4603 else
4605 }
4606 }
4609 else
4611 }
4615 }
4616 \f
4618 /* Subroutine of fold, looking inside expressions of the form
4619 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4620 of the COND_EXPR. This function is being used also to optimize
4621 A op B ? C : A, by reversing the comparison first.
4623 Return a folded expression whose code is not a COND_EXPR
4624 anymore, or NULL_TREE if no folding opportunity is found. */
4626 static tree
4629 {
4634 tree tem;
4639 /* If we have A op 0 ? A : -A, consider applying the following
4640 transformations:
4642 A == 0? A : -A same as -A
4643 A != 0? A : -A same as A
4644 A >= 0? A : -A same as abs (A)
4645 A > 0? A : -A same as abs (A)
4646 A <= 0? A : -A same as -abs (A)
4647 A < 0? A : -A same as -abs (A)
4649 None of these transformations work for modes with signed
4650 zeros. If A is +/-0, the first two transformations will
4651 change the sign of the result (from +0 to -0, or vice
4652 versa). The last four will fix the sign of the result,
4653 even though the original expressions could be positive or
4654 negative, depending on the sign of A.
4656 Note that all these transformations are correct if A is
4657 NaN, since the two alternatives (A and -A) are also NaNs. */
4664 /* In the case that A is of the form X-Y, '-A' (arg2) may
4665 have already been folded to Y-X, check for that. */
4673 {
4687 /* Fall through. */
4709 }
4711 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4712 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4713 both transformations are correct when A is NaN: A != 0
4714 is then true, and A == 0 is false. */
4718 {
4723 }
4725 /* Try some transformations of A op B ? A : B.
4727 A == B? A : B same as B
4728 A != B? A : B same as A
4729 A >= B? A : B same as max (A, B)
4730 A > B? A : B same as max (B, A)
4731 A <= B? A : B same as min (A, B)
4732 A < B? A : B same as min (B, A)
4734 As above, these transformations don't work in the presence
4735 of signed zeros. For example, if A and B are zeros of
4736 opposite sign, the first two transformations will change
4737 the sign of the result. In the last four, the original
4738 expressions give different results for (A=+0, B=-0) and
4739 (A=-0, B=+0), but the transformed expressions do not.
4741 The first two transformations are correct if either A or B
4742 is a NaN. In the first transformation, the condition will
4743 be false, and B will indeed be chosen. In the case of the
4744 second transformation, the condition A != B will be true,
4745 and A will be chosen.
4747 The conversions to max() and min() are not correct if B is
4748 a number and A is not. The conditions in the original
4749 expressions will be false, so all four give B. The min()
4750 and max() versions would give a NaN instead. */
4753 /* Avoid these transformations if the COND_EXPR may be used
4754 as an lvalue in the C++ front-end. PR c++/19199. */
4755 && (in_gimple_form
4761 {
4766 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4768 {
4772 }
4775 {
4784 /* In C++ a ?: expression can be an lvalue, so put the
4785 operand which will be used if they are equal first
4786 so that we can convert this back to the
4787 corresponding COND_EXPR. */
4789 {
4798 }
4805 {
4814 }
4829 }
4830 }
4832 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4833 we might still be able to simplify this. For example,
4834 if C1 is one less or one more than C2, this might have started
4835 out as a MIN or MAX and been transformed by this function.
4836 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4842 {
4846 /* We can replace A with C1 in this case. */
4851 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
4852 MIN_EXPR, to preserve the signedness of the comparison. */
4854 OEP_ONLY_CONST)
4858 OEP_ONLY_CONST))
4859 {
4862 arg2));
4865 }
4869 /* If C1 is C2 - 1, this is min(A, C2), with the same care
4870 as above. */
4872 OEP_ONLY_CONST)
4876 OEP_ONLY_CONST))
4877 {
4880 arg2));
4883 }
4887 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
4888 MAX_EXPR, to preserve the signedness of the comparison. */
4890 OEP_ONLY_CONST)
4894 OEP_ONLY_CONST))
4895 {
4898 arg2));
4900 }
4904 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
4906 OEP_ONLY_CONST)
4910 OEP_ONLY_CONST))
4911 {
4914 arg2));
4916 }
4922 }
4925 }
4928 \f
4929 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4930 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
4931 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
4932 false) >= 2)
4933 #endif
4935 /* EXP is some logical combination of boolean tests. See if we can
4936 merge it into some range test. Return the new tree if so. */
4938 static tree
4941 {
4957 /* If this is an OR operation, invert both sides; we will invert
4958 again at the end. */
4962 /* If both expressions are the same, if we can merge the ranges, and we
4963 can build the range test, return it or it inverted. If one of the
4964 ranges is always true or always false, consider it to be the same
4965 expression as the other. */
4973 {
4977 }
4979 /* On machines where the branch cost is expensive, if this is a
4980 short-circuited branch and the underlying object on both sides
4981 is the same, make a non-short-circuit operation. */
4987 {
4988 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4989 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4990 which cases we can't do this. */
4998 {
5007 {
5010 WARN_STRICT_OVERFLOW_COMPARISON);
5014 }
5015 }
5016 }
5019 }
5020 \f
5021 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5022 bit value. Arrange things so the extra bits will be set to zero if and
5023 only if C is signed-extended to its full width. If MASK is nonzero,
5024 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5026 static tree
5028 {
5031 tree temp;
5036 /* We work by getting just the sign bit into the low-order bit, then
5037 into the high-order bit, then sign-extend. We then XOR that value
5038 with C. */
5041 /* We must use a signed type in order to get an arithmetic right shift.
5042 However, we must also avoid introducing accidental overflows, so that
5043 a subsequent call to integer_zerop will work. Hence we must
5044 do the type conversion here. At this point, the constant is either
5045 zero or one, and the conversion to a signed type can never overflow.
5046 We could get an overflow if this conversion is done anywhere else. */
5055 /* If necessary, convert the type back to match the type of C. */
5060 }
5061 \f
5062 /* For an expression that has the form
5063 (A && B) || ~B
5064 or
5065 (A || B) && ~B,
5066 we can drop one of the inner expressions and simplify to
5067 A || ~B
5068 or
5069 A && ~B
5070 LOC is the location of the resulting expression. OP is the inner
5071 logical operation; the left-hand side in the examples above, while CMPOP
5072 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5073 removing a condition that guards another, as in
5074 (A != NULL && A->...) || A == NULL
5075 which we must not transform. If RHS_ONLY is true, only eliminate the
5076 right-most operand of the inner logical operation. */
5078 static tree
5081 {
5099 {
5102 {
5105 }
5106 }
5108 {
5111 {
5114 }
5115 }
5130 }
5132 /* Find ways of folding logical expressions of LHS and RHS:
5133 Try to merge two comparisons to the same innermost item.
5134 Look for range tests like "ch >= '0' && ch <= '9'".
5135 Look for combinations of simple terms on machines with expensive branches
5136 and evaluate the RHS unconditionally.
5138 For example, if we have p->a == 2 && p->b == 4 and we can make an
5139 object large enough to span both A and B, we can do this with a comparison
5140 against the object ANDed with the a mask.
5142 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5143 operations to do this with one comparison.
5145 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5146 function and the one above.
5148 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5149 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5151 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5152 two operands.
5154 We return the simplified tree or 0 if no optimization is possible. */
5156 static tree
5159 {
5160 /* If this is the "or" of two comparisons, we can do something if
5161 the comparisons are NE_EXPR. If this is the "and", we can do something
5162 if the comparisons are EQ_EXPR. I.e.,
5163 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5165 WANTED_CODE is this operation code. For single bit fields, we can
5166 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5167 comparison for one-bit fields. */
5187 /* Start by getting the comparison codes. Fail if anything is volatile.
5188 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5189 it were surrounded with a NE_EXPR. */
5198 {
5202 }
5205 {
5209 }
5220 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5223 {
5226 {
5231 }
5234 {
5240 }
5241 }
5246 /* If the RHS can be evaluated unconditionally and its operands are
5247 simple, it wins to evaluate the RHS unconditionally on machines
5248 with expensive branches. In this case, this isn't a comparison
5249 that can be merged. */
5256 {
5257 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5268 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5278 }
5280 /* See if the comparisons can be merged. Then get all the parameters for
5281 each side. */
5305 /* It must be true that the inner operation on the lhs of each
5306 comparison must be the same if we are to be able to do anything.
5307 Then see if we have constants. If not, the same must be true for
5308 the rhs's. */
5319 else
5322 /* If either comparison code is not correct for our logical operation,
5323 fail. However, we can convert a one-bit comparison against zero into
5324 the opposite comparison against that bit being set in the field. */
5328 {
5330 {
5331 /* Make the left operand unsigned, since we are only interested
5332 in the value of one bit. Otherwise we are doing the wrong
5333 thing below. */
5336 }
5337 else
5339 }
5341 /* This is analogous to the code for l_const above. */
5343 {
5345 {
5348 }
5349 else
5351 }
5353 /* See if we can find a mode that contains both fields being compared on
5354 the left. If we can't, fail. Otherwise, update all constants and masks
5355 to be relative to a field of that size. */
5360 volatilep);
5370 {
5373 }
5381 {
5388 {
5392 }
5393 }
5395 {
5402 {
5406 }
5407 }
5409 /* If the right sides are not constant, do the same for it. Also,
5410 disallow this optimization if a size or signedness mismatch occurs
5411 between the left and right sides. */
5413 {
5416 /* Make sure the two fields on the right
5417 correspond to the left without being swapped. */
5425 volatilep);
5435 {
5438 }
5447 /* Make a mask that corresponds to both fields being compared.
5448 Do this for both items being compared. If the operands are the
5449 same size and the bits being compared are in the same position
5450 then we can do this by masking both and comparing the masked
5451 results. */
5455 {
5467 }
5469 /* There is still another way we can do something: If both pairs of
5470 fields being compared are adjacent, we may be able to make a wider
5471 field containing them both.
5473 Note that we still must mask the lhs/rhs expressions. Furthermore,
5474 the mask must be shifted to account for the shift done by
5475 make_bit_field_ref. */
5480 {
5481 tree type;
5495 /* Convert to the smaller type before masking out unwanted bits. */
5498 {
5500 {
5504 }
5506 {
5510 }
5511 }
5520 }
5523 }
5525 /* Handle the case of comparisons with constants. If there is something in
5526 common between the masks, those bits of the constants must be the same.
5527 If not, the condition is always false. Test for this to avoid generating
5528 incorrect code below. */
5533 {
5535 {
5538 }
5539 else
5540 {
5543 }
5544 }
5546 /* Construct the expression we will return. First get the component
5547 reference we will make. Unless the mask is all ones the width of
5548 that field, perform the mask operation. Then compare with the
5549 merged constant. */
5559 }
5560 \f
5561 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5562 constant. */
5564 static tree
5567 {
5570 tree comp_const;
5571 tree minmax_const;
5573 tree inner;
5584 /* If something does not permit us to optimize, return the original tree. */
5592 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5593 and GT_EXPR, doing the rest with recursive calls using logical
5594 simplifications. */
5596 {
5598 {
5599 tree tem
5606 }
5609 return
5611 optimize_minmax_comparison
5613 optimize_minmax_comparison
5618 /* MAX (X, 0) == 0 -> X <= 0 */
5622 /* MAX (X, 0) == 5 -> X == 5 */
5626 /* MAX (X, 0) == -1 -> false */
5630 /* MIN (X, 0) == 0 -> X >= 0 */
5634 /* MIN (X, 0) == 5 -> false */
5637 else
5638 /* MIN (X, 0) == -1 -> X == -1 */
5643 /* MAX (X, 0) > 0 -> X > 0
5644 MAX (X, 0) > 5 -> X > 5 */
5648 /* MAX (X, 0) > -1 -> true */
5652 /* MIN (X, 0) > 0 -> false
5653 MIN (X, 0) > 5 -> false */
5656 else
5657 /* MIN (X, 0) > -1 -> X > -1 */
5662 }
5663 }
5664 \f
5665 /* T is an integer expression that is being multiplied, divided, or taken a
5666 modulus (CODE says which and what kind of divide or modulus) by a
5667 constant C. See if we can eliminate that operation by folding it with
5668 other operations already in T. WIDE_TYPE, if non-null, is a type that
5669 should be used for the computation if wider than our type.
5671 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5672 (X * 2) + (Y * 4). We must, however, be assured that either the original
5673 expression would not overflow or that overflow is undefined for the type
5674 in the language in question.
5676 If we return a non-null expression, it is an equivalent form of the
5677 original computation, but need not be in the original type.
5679 We set *STRICT_OVERFLOW_P to true if the return values depends on
5680 signed overflow being undefined. Otherwise we do not change
5681 *STRICT_OVERFLOW_P. */
5683 static tree
5686 {
5687 /* To avoid exponential search depth, refuse to allow recursion past
5688 three levels. Beyond that (1) it's highly unlikely that we'll find
5689 something interesting and (2) we've probably processed it before
5690 when we built the inner expression. */
5693 tree ret;
5698 depth++;
5700 depth--;
5703 }
5705 static tree
5708 {
5719 /* Don't deal with constants of zero here; they confuse the code below. */
5729 /* Note that we need not handle conditional operations here since fold
5730 already handles those cases. So just do arithmetic here. */
5732 {
5734 /* For a constant, we can always simplify if we are a multiply
5735 or (for divide and modulus) if it is a multiple of our constant. */
5743 /* If op0 is an expression ... */
5749 /* ... and has wrapping overflow, and its type is smaller
5750 than ctype, then we cannot pass through as widening. */
5754 /* ... or this is a truncation (t is narrower than op0),
5755 then we cannot pass through this narrowing. */
5758 /* ... or signedness changes for division or modulus,
5759 then we cannot pass through this conversion. */
5763 /* ... or has undefined overflow while the converted to
5764 type has not, we cannot do the operation in the inner type
5765 as that would introduce undefined overflow. */
5770 /* Pass the constant down and see if we can make a simplification. If
5771 we can, replace this expression with the inner simplification for
5772 possible later conversion to our or some other type. */
5777 code == MULT_EXPR
5779 strict_overflow_p))))
5784 /* If widening the type changes it from signed to unsigned, then we
5785 must avoid building ABS_EXPR itself as unsigned. */
5787 {
5791 {
5794 }
5796 }
5797 /* If the constant is negative, we cannot simplify this. */
5800 /* FALLTHROUGH */
5802 /* For division and modulus, type can't be unsigned, as e.g.
5803 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
5804 For signed types, even with wrapping overflow, this is fine. */
5813 /* If widening the type changes the signedness, then we can't perform
5814 this optimization as that changes the result. */
5818 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5824 {
5831 }
5835 /* If the second operand is constant, this is a multiplication
5836 or floor division, by a power of two, so we can treat it that
5837 way unless the multiplier or divisor overflows. Signed
5838 left-shift overflow is implementation-defined rather than
5839 undefined in C90, so do not convert signed left shift into
5840 multiplication. */
5843 /* const_binop may not detect overflow correctly,
5844 so check for it explicitly here. */
5848 size_one_node,
5849 op1)))
5853 ctype,
5855 t1),
5860 /* See if we can eliminate the operation on both sides. If we can, we
5861 can return a new PLUS or MINUS. If we can't, the only remaining
5862 cases where we can do anything are if the second operand is a
5863 constant. */
5869 /* If not multiplication, we can only do this if both operands
5870 are divisible by c. */
5873 {
5878 }
5880 /* If this was a subtraction, negate OP1 and set it to be an addition.
5881 This simplifies the logic below. */
5883 {
5885 /* If OP1 was not easily negatable, the constant may be OP0. */
5887 {
5894 }
5895 }
5900 /* If either OP1 or C are negative, this optimization is not safe for
5901 some of the division and remainder types while for others we need
5902 to change the code. */
5904 {
5912 }
5914 /* If it's a multiply or a division/modulus operation of a multiple
5915 of our constant, do the operation and verify it doesn't overflow. */
5918 {
5921 /* We allow the constant to overflow with wrapping semantics. */
5925 }
5926 else
5929 /* If we have an unsigned type, we cannot widen the operation since it
5930 will change the result if the original computation overflowed. */
5934 /* If we were able to eliminate our operation from the first side,
5935 apply our operation to the second side and reform the PLUS. */
5939 /* The last case is if we are a multiply. In that case, we can
5940 apply the distributive law to commute the multiply and addition
5941 if the multiplication of the constants doesn't overflow
5942 and overflow is defined. With undefined overflow
5943 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
5949 op1);
5954 /* We have a special case here if we are doing something like
5955 (C * 8) % 4 since we know that's zero. */
5958 /* If the multiplication can overflow we cannot optimize this. */
5962 {
5965 }
5967 /* ... fall through ... */
5971 /* If we can extract our operation from the LHS, do so and return a
5972 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5973 do something only if the second operand is a constant. */
5987 /* If these are the same operation types, we can associate them
5988 assuming no overflow. */
5990 {
6002 }
6004 /* If these operations "cancel" each other, we have the main
6005 optimizations of this pass, which occur when either constant is a
6006 multiple of the other, in which case we replace this with either an
6007 operation or CODE or TCODE.
6009 If we have an unsigned type, we cannot do this since it will change
6010 the result if the original computation overflowed. */
6017 {
6019 {
6026 }
6028 {
6035 }
6036 }
6041 }
6044 }
6045 \f
6046 /* Return a node which has the indicated constant VALUE (either 0 or
6047 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6048 and is of the indicated TYPE. */
6050 tree
6052 {
6061 else
6063 }
6066 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6067 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6068 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6069 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6070 COND is the first argument to CODE; otherwise (as in the example
6071 given here), it is the second argument. TYPE is the type of the
6072 original expression. Return NULL_TREE if no simplification is
6073 possible. */
6075 static tree
6080 {
6090 {
6094 /* If this operand throws an expression, then it does not make
6095 sense to try to perform a logical or arithmetic operation
6096 involving it. */
6101 }
6102 else
6103 {
6108 }
6113 /* This transformation is only worthwhile if we don't have to wrap ARG
6114 in a SAVE_EXPR and the operation can be simplified without recursing
6115 on at least one of the branches once its pushed inside the COND_EXPR. */
6124 {
6128 else
6130 }
6132 {
6136 else
6138 }
6140 /* Check that we have simplified at least one of the branches. */
6145 }
6147 \f
6148 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6150 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6151 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6152 ADDEND is the same as X.
6154 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6155 and finite. The problematic cases are when X is zero, and its mode
6156 has signed zeros. In the case of rounding towards -infinity,
6157 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6158 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6160 bool
6162 {
6166 /* Don't allow the fold with -fsignaling-nans. */
6170 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6174 /* In a vector or complex, we would need to check the sign of all zeros. */
6178 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6182 /* The mode has signed zeros, and we have to honor their sign.
6183 In this situation, there is only one case we can return true for.
6184 X - 0 is the same as X unless rounding towards -infinity is
6185 supported. */
6187 }
6189 /* Subroutine of fold() that checks comparisons of built-in math
6190 functions against real constants.
6192 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6193 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6194 is the type of the result and ARG0 and ARG1 are the operands of the
6195 comparison. ARG1 must be a TREE_REAL_CST.
6197 The function returns the constant folded tree if a simplification
6198 can be made, and NULL_TREE otherwise. */
6200 static tree
6204 {
6205 REAL_VALUE_TYPE c;
6208 {
6214 {
6215 /* sqrt(x) < y is always false, if y is negative. */
6219 /* sqrt(x) > y is always true, if y is negative and we
6220 don't care about NaNs, i.e. negative values of x. */
6224 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6227 }
6229 {
6230 REAL_VALUE_TYPE c2;
6236 {
6237 /* sqrt(x) > y is x == +Inf, when y is very large. */
6242 /* sqrt(x) > y is always false, when y is very large
6243 and we don't care about infinities. */
6245 }
6247 /* sqrt(x) > c is the same as x > c*c. */
6250 }
6252 {
6253 REAL_VALUE_TYPE c2;
6259 {
6260 /* sqrt(x) < y is always true, when y is a very large
6261 value and we don't care about NaNs or Infinities. */
6265 /* sqrt(x) < y is x != +Inf when y is very large and we
6266 don't care about NaNs. */
6271 /* sqrt(x) < y is x >= 0 when y is very large and we
6272 don't care about Infinities. */
6277 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6282 dconst0)),
6285 c2)));
6286 }
6288 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6293 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6298 dconst0)),
6301 c2)));
6302 }
6303 }
6306 }
6308 /* Subroutine of fold() that optimizes comparisons against Infinities,
6309 either +Inf or -Inf.
6311 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6312 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6313 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6315 The function returns the constant folded tree if a simplification
6316 can be made, and NULL_TREE otherwise. */
6318 static tree
6321 {
6323 REAL_VALUE_TYPE max;
6324 tree temp;
6329 /* For negative infinity swap the sense of the comparison. */
6335 {
6337 /* x > +Inf is always false, if with ignore sNANs. */
6343 /* x <= +Inf is always true, if we don't case about NaNs. */
6347 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6353 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6359 /* x < +Inf is always equal to x <= DBL_MAX. */
6365 /* x != +Inf is always equal to !(x > DBL_MAX). */
6377 }
6380 }
6382 /* Subroutine of fold() that optimizes comparisons of a division by
6383 a nonzero integer constant against an integer constant, i.e.
6384 X/C1 op C2.
6386 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6387 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6388 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6390 The function returns the constant folded tree if a simplification
6391 can be made, and NULL_TREE otherwise. */
6393 static tree
6396 {
6404 /* We have to do this the hard way to detect unsigned overflow.
6405 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6411 {
6416 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6420 }
6422 {
6426 {
6445 }
6446 }
6447 else
6448 {
6449 /* A negative divisor reverses the relational operators. */
6455 {
6474 }
6475 }
6478 {
6499 {
6502 }
6507 {
6510 }
6515 {
6518 }
6523 {
6526 }
6531 }
6534 }
6537 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6538 equality/inequality test, then return a simplified form of the test
6539 using a sign testing. Otherwise return NULL. TYPE is the desired
6540 result type. */
6542 static tree
6545 tree result_type)
6546 {
6547 /* If this is testing a single bit, we can optimize the test. */
6551 {
6552 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6553 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6557 /* This is only a win if casting to a signed type is cheap,
6558 i.e. when arg00's type is not a partial mode. */
6561 {
6564 result_type,
6567 }
6568 }
6571 }
6573 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6574 equality/inequality test, then return a simplified form of
6575 the test using shifts and logical operations. Otherwise return
6576 NULL. TYPE is the desired result type. */
6578 tree
6581 {
6582 /* If this is testing a single bit, we can optimize the test. */
6586 {
6595 /* First, see if we can fold the single bit test into a sign-bit
6596 test. */
6598 result_type);
6602 /* Otherwise we have (A & C) != 0 where C is a single bit,
6603 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6604 Similarly for (A & C) == 0. */
6606 /* If INNER is a right shift of a constant and it plus BITNUM does
6607 not overflow, adjust BITNUM and INNER. */
6613 {
6616 }
6618 /* If we are going to be able to omit the AND below, we must do our
6619 operations as unsigned. If we must use the AND, we have a choice.
6620 Normally unsigned is faster, but for some machines signed is. */
6621 #ifdef LOAD_EXTEND_OP
6624 #else
6626 #endif
6642 /* Put the AND last so it can combine with more things. */
6645 /* Make sure to return the proper type. */
6649 }
6651 }
6653 /* Check whether we are allowed to reorder operands arg0 and arg1,
6654 such that the evaluation of arg1 occurs before arg0. */
6656 static bool
6658 {
6665 }
6667 /* Test whether it is preferable two swap two operands, ARG0 and
6668 ARG1, for example because ARG0 is an integer constant and ARG1
6669 isn't. If REORDER is true, only recommend swapping if we can
6670 evaluate the operands in reverse order. */
6672 bool
6674 {
6710 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6711 for commutative and comparison operators. Ensuring a canonical
6712 form allows the optimizers to find additional redundancies without
6713 having to explicitly check for both orderings. */
6719 /* Put SSA_NAMEs last. */
6725 /* Put variables last. */
6732 }
6734 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6735 ARG0 is extended to a wider type. */
6737 static tree
6740 {
6742 tree arg1_unw;
6751 #ifdef HAVE_canonicalize_funcptr_for_compare
6752 /* Disable this optimization if we're casting a function pointer
6753 type on targets that require function pointer canonicalization. */
6758 #endif
6765 /* If possible, express the comparison in the shorter mode. */
6785 /* If we are comparing with the integer that does not fit into the range
6786 of the shorter type, the result is known. */
6797 {
6824 }
6827 }
6829 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6830 ARG0 just the signedness is changed. */
6832 static tree
6835 {
6836 tree arg0_inner;
6846 #ifdef HAVE_canonicalize_funcptr_for_compare
6847 /* Disable this optimization if we're casting a function pointer
6848 type on targets that require function pointer canonicalization. */
6853 #endif
6874 else
6878 }
6880 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
6881 step of the array. Reconstructs s and delta in the case of s *
6882 delta being an integer constant (and thus already folded). ADDR is
6883 the address. MULT is the multiplicative expression. If the
6884 function succeeds, the new address expression is returned.
6885 Otherwise NULL_TREE is returned. LOC is the location of the
6886 resulting expression. */
6888 static tree
6890 {
6894 tree itype;
6897 /* Strip the nops that might be added when converting op1 to sizetype. */
6900 /* Canonicalize op1 into a possibly non-constant delta
6901 and an INTEGER_CST s. */
6903 {
6910 {
6913 }
6915 {
6918 }
6919 else
6921 }
6923 {
6926 }
6927 else
6928 {
6929 /* Simulate we are delta * 1. */
6932 }
6934 /* Handle &x.array the same as we would handle &x.array[0]. */
6937 {
6938 tree domain;
6940 /* Remember if this was a multi-dimensional array. */
6954 {
6957 }
6958 else
6959 {
6960 /* Try if delta is a multiple of step. */
6965 }
6967 /* Only fold here if we can verify we do not overflow one
6968 dimension of a multi-dimensional array. */
6970 {
6971 tree tmp;
6985 }
6987 /* We found a suitable component reference. */
6994 fold_build2_loc
6997 TYPE_MIN_VALUE
7002 }
7004 cont:
7007 {
7009 {
7010 tree domain;
7012 /* Remember if this was a multi-dimensional array. */
7026 {
7029 }
7030 else
7031 {
7032 /* Try if delta is a multiple of step. */
7037 }
7039 /* Only fold here if we can verify we do not overflow one
7040 dimension of a multi-dimensional array. */
7042 {
7043 tree tmp;
7058 }
7061 }
7062 else
7067 }
7069 /* We found the suitable array reference. So copy everything up to it,
7070 and replace the index. */
7078 {
7082 }
7089 }
7092 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7093 means A >= Y && A != MAX, but in this case we know that
7094 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7096 static tree
7098 {
7105 else
7114 {
7117 }
7119 {
7122 }
7123 else
7130 {
7131 /* Convert the pointer types into integer before taking the difference. */
7135 }
7136 else
7143 }
7145 /* Fold a sum or difference of at least one multiplication.
7146 Returns the folded tree or NULL if no simplification could be made. */
7148 static tree
7151 {
7155 /* (A * C) +- (B * C) -> (A+-B) * C.
7156 (A * C) +- A -> A * (C+-1).
7157 We are most concerned about the case where C is a constant,
7158 but other combinations show up during loop reduction. Since
7159 it is not difficult, try all four possibilities. */
7162 {
7165 }
7167 {
7170 }
7171 else
7172 {
7173 /* We cannot generate constant 1 for fract. */
7178 }
7180 {
7183 }
7185 {
7187 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7188 the purpose of this canonicalization. */
7192 {
7195 }
7196 else
7198 }
7199 else
7200 {
7201 /* We cannot generate constant 1 for fract. */
7206 }
7218 /* No identical multiplicands; see if we can find a common
7219 power-of-two factor in non-power-of-two multiplies. This
7220 can help in multi-dimensional array access. */
7223 {
7226 tree maybe_same;
7230 /* Move min of absolute values to int11. */
7232 {
7237 }
7238 else
7242 /* The remainder should not be a constant, otherwise we
7243 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7244 increased the number of multiplications necessary. */
7246 {
7254 }
7255 }
7265 }
7267 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7268 specified by EXPR into the buffer PTR of length LEN bytes.
7269 Return the number of bytes placed in the buffer, or zero
7270 upon failure. */
7272 static int
7274 {
7288 {
7290 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7291 number of bytes. */
7295 {
7302 else
7304 }
7305 else
7310 }
7312 }
7315 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7316 specified by EXPR into the buffer PTR of length LEN bytes.
7317 Return the number of bytes placed in the buffer, or zero
7318 upon failure. */
7320 static int
7322 {
7326 FIXED_VALUE_TYPE value;
7342 }
7345 /* Subroutine of native_encode_expr. Encode the REAL_CST
7346 specified by EXPR into the buffer PTR of length LEN bytes.
7347 Return the number of bytes placed in the buffer, or zero
7348 upon failure. */
7350 static int
7352 {
7358 /* There are always 32 bits in each long, no matter the size of
7359 the hosts long. We handle floating point representations with
7360 up to 192 bits. */
7374 {
7379 {
7386 else
7388 }
7389 else
7395 }
7397 }
7399 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7400 specified by EXPR into the buffer PTR of length LEN bytes.
7401 Return the number of bytes placed in the buffer, or zero
7402 upon failure. */
7404 static int
7406 {
7408 tree part;
7423 }
7426 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7427 specified by EXPR into the buffer PTR of length LEN bytes.
7428 Return the number of bytes placed in the buffer, or zero
7429 upon failure. */
7431 static int
7433 {
7443 {
7445 {
7448 }
7459 }
7461 }
7464 /* Subroutine of native_encode_expr. Encode the STRING_CST
7465 specified by EXPR into the buffer PTR of length LEN bytes.
7466 Return the number of bytes placed in the buffer, or zero
7467 upon failure. */
7469 static int
7471 {
7473 HOST_WIDE_INT total_bytes;
7487 {
7490 {
7493 }
7496 }
7497 else
7500 }
7503 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7504 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7505 buffer PTR of length LEN bytes. If OFF is not -1 then start
7506 the encoding at byte offset OFF and encode at most LEN bytes.
7507 Return the number of bytes placed in the buffer, or zero upon failure. */
7509 int
7511 {
7513 {
7534 }
7535 }
7538 /* Subroutine of native_interpret_expr. Interpret the contents of
7539 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7540 If the buffer cannot be interpreted, return NULL_TREE. */
7542 static tree
7544 {
7554 }
7557 /* Subroutine of native_interpret_expr. Interpret the contents of
7558 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7559 If the buffer cannot be interpreted, return NULL_TREE. */
7561 static tree
7563 {
7565 double_int result;
7566 FIXED_VALUE_TYPE fixed_value;
7576 }
7579 /* Subroutine of native_interpret_expr. Interpret the contents of
7580 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7581 If the buffer cannot be interpreted, return NULL_TREE. */
7583 static tree
7585 {
7590 /* There are always 32 bits in each long, no matter the size of
7591 the hosts long. We handle floating point representations with
7592 up to 192 bits. */
7593 REAL_VALUE_TYPE r;
7604 {
7607 {
7614 else
7616 }
7617 else
7622 }
7626 }
7629 /* Subroutine of native_interpret_expr. Interpret the contents of
7630 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7631 If the buffer cannot be interpreted, return NULL_TREE. */
7633 static tree
7635 {
7650 }
7653 /* Subroutine of native_interpret_expr. Interpret the contents of
7654 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7655 If the buffer cannot be interpreted, return NULL_TREE. */
7657 static tree
7659 {
7672 {
7677 }
7679 }
7682 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7683 the buffer PTR of length LEN as a constant of type TYPE. For
7684 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7685 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7686 return NULL_TREE. */
7688 tree
7690 {
7692 {
7714 }
7715 }
7717 /* Returns true if we can interpret the contents of a native encoding
7718 as TYPE. */
7720 static bool
7722 {
7724 {
7737 }
7738 }
7740 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7741 TYPE at compile-time. If we're unable to perform the conversion
7742 return NULL_TREE. */
7744 static tree
7746 {
7747 /* We support up to 512-bit values (for V8DFmode). */
7751 /* Check that the host and target are sane. */
7760 }
7762 /* Build an expression for the address of T. Folds away INDIRECT_REF
7763 to avoid confusing the gimplify process. */
7765 tree
7767 {
7768 /* The size of the object is not relevant when talking about its address. */
7773 {
7778 }
7788 {
7793 }
7794 else
7798 }
7800 /* Build an expression for the address of T. */
7802 tree
7804 {
7808 }
7812 /* Fold a unary expression of code CODE and type TYPE with operand
7813 OP0. Return the folded expression if folding is successful.
7814 Otherwise, return NULL_TREE. */
7816 static tree
7818 {
7819 tree tem;
7820 tree arg0;
7828 {
7831 {
7832 /* Don't use STRIP_NOPS, because signedness of argument type
7833 matters. */
7835 }
7836 else
7837 {
7838 /* Strip any conversions that don't change the mode. This
7839 is safe for every expression, except for a comparison
7840 expression because its signedness is derived from its
7841 operands.
7843 Note that this is done as an internal manipulation within
7844 the constant folder, in order to find the simplest
7845 representation of the arguments so that their form can be
7846 studied. In any cases, the appropriate type conversions
7847 should be put back in the tree that will get out of the
7848 constant folder. */
7850 }
7851 }
7854 {
7861 {
7875 /* If this was a conversion, and all we did was to move into
7876 inside the COND_EXPR, bring it back out. But leave it if
7877 it is a conversion from integer to integer and the
7878 result precision is no wider than a word since such a
7879 conversion is cheap and may be optimized away by combine,
7880 while it couldn't if it were outside the COND_EXPR. Then return
7881 so we don't get into an infinite recursion loop taking the
7882 conversion out and then back in. */
7894 && (INTEGRAL_TYPE_P
7907 }
7908 }
7911 {
7913 /* Re-association barriers around constants and other re-association
7914 barriers can be removed. */
7925 CASE_CONVERT:
7932 {
7933 /* If we have (type) (a CMP b) and type is an integral type, return
7934 new expression involving the new type. Canonicalize
7935 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7936 non-integral type.
7937 Do not fold the result as that would not simplify further, also
7938 folding again results in recursions. */
7948 }
7950 /* Handle cases of two conversions in a row. */
7952 {
7974 /* In addition to the cases of two conversions in a row
7975 handled below, if we are converting something to its own
7976 type via an object of identical or wider precision, neither
7977 conversion is needed. */
7984 /* Likewise, if the intermediate and initial types are either both
7985 float or both integer, we don't need the middle conversion if the
7986 former is wider than the latter and doesn't change the signedness
7987 (for integers). Avoid this if the final type is a pointer since
7988 then we sometimes need the middle conversion. Likewise if the
7989 final type has a precision not equal to the size of its mode. */
7998 && ! final_ptr
8002 /* If we have a sign-extension of a zero-extended value, we can
8003 replace that by a single zero-extension. Likewise if the
8004 final conversion does not change precision we can drop the
8005 intermediate conversion. */
8012 /* Two conversions in a row are not needed unless:
8013 - some conversion is floating-point (overstrict for now), or
8014 - some conversion is a vector (overstrict for now), or
8015 - the intermediate type is narrower than both initial and
8016 final, or
8017 - the intermediate type and innermost type differ in signedness,
8018 and the outermost type is wider than the intermediate, or
8019 - the initial type is a pointer type and the precisions of the
8020 intermediate and final types differ, or
8021 - the final type is a pointer type and the precisions of the
8022 initial and intermediate types differ. */
8036 }
8038 /* Handle (T *)&A.B.C for A being of type T and B and C
8039 living at offset zero. This occurs frequently in
8040 C++ upcasting and then accessing the base. */
8044 {
8046 tree offset;
8052 /* If the reference was to a (constant) zero offset, we can use
8053 the address of the base if it has the same base type
8054 as the result type and the pointer type is unqualified. */
8061 }
8065 /* Detect assigning a bitfield. */
8067 && DECL_BIT_FIELD
8069 {
8070 /* Don't leave an assignment inside a conversion
8071 unless assigning a bitfield. */
8073 /* First do the assignment, then return converted constant. */
8078 }
8080 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8081 constants (if x has signed type, the sign bit cannot be set
8082 in c). This folds extension into the BIT_AND_EXPR.
8083 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8084 very likely don't have maximal range for their precision and this
8085 transformation effectively doesn't preserve non-maximal ranges. */
8089 {
8100 <= HOST_BITS_PER_WIDE_INT
8102 {
8106 cst &= HOST_WIDE_INT_M1U
8109 #ifdef LOAD_EXTEND_OP
8111 && !flag_syntax_only
8114 {
8118 }
8119 #endif
8120 }
8122 {
8127 }
8128 }
8130 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8131 when one of the new casts will fold away. Conservatively we assume
8132 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8139 {
8143 return fold_build_pointer_plus_loc
8145 }
8147 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8148 of the same precision, and X is an integer type not narrower than
8149 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8155 {
8161 }
8163 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8164 type of X and Y (integer types only). */
8169 {
8170 /* Be careful not to introduce new overflows. */
8171 tree mult_type;
8174 else
8178 {
8185 }
8186 }
8210 /* For integral conversions with the same precision or pointer
8211 conversions use a NOP_EXPR instead. */
8219 /* Strip inner integral conversions that do not change the precision. */
8243 /* Convert fabs((double)float) into (double)fabsf(float). */
8246 {
8252 targ0));
8253 }
8254 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8260 /* Strip sign ops from argument. */
8262 {
8267 }
8274 {
8280 }
8282 {
8287 }
8297 /* Convert ~ (-A) to A - 1. */
8302 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8311 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8326 /* Perform BIT_NOT_EXPR on each element individually. */
8328 {
8330 tree elem;
8335 {
8341 }
8344 }
8348 {
8355 }
8361 /* Note that the operand of this must be an int
8362 and its values must be 0 or 1.
8363 ("true" is a fixed value perhaps depending on the language,
8364 but we don't handle values other than 1 correctly yet.) */
8379 {
8387 }
8389 {
8394 }
8396 {
8400 {
8409 }
8410 }
8422 {
8430 }
8432 {
8436 }
8438 {
8442 {
8451 }
8452 }
8456 /* Fold *&X to X if X is an lvalue. */
8458 {
8465 }
8472 {
8491 else
8495 {
8499 }
8502 }
8507 {
8520 {
8525 }
8528 {
8533 }
8536 }
8541 }
8543 /* Given an expression tree EXP, set the EXPR_FOLDED flag, and if it is
8544 a nop, recursively set the EXPR_FOLDED flag of its operand. */
8546 static void
8548 {
8549 // Can not be called any more -- the bit is used for other purpose - wide-int
8550 // support
8552 /* FIXME -- can not set the flag on SSA_NAME, the flag overlaps
8553 with the version member. */
8559 /* If EXP is a nop (i.e. NON_LVALUE_EXPRs and NOP_EXPRs), we need to
8560 recursively set the EXPR_FOLDED flag of its operand because the
8561 expression will be stripped later. */
8565 {
8567 /* FIXME -- can not set the flag on SSA_NAME, the flag overlaps
8568 with the version member. */
8571 }
8572 }
8574 /* Fold a unary expression of code CODE and type TYPE with operand
8575 OP0. Return the folded expression if folding is successful.
8576 Otherwise, return NULL_TREE.
8577 This is a wrapper around fold_unary_1 function (which does the
8578 actual folding). Set the EXPR_FOLDED flag of the folded expression
8579 if folding is successful. */
8581 tree
8583 {
8586 }
8588 /* If the operation was a conversion do _not_ mark a resulting constant
8589 with TREE_OVERFLOW if the original constant was not. These conversions
8590 have implementation defined behavior and retaining the TREE_OVERFLOW
8591 flag here would confuse later passes such as VRP. */
8592 tree
8595 {
8604 }
8606 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8607 operands OP0 and OP1. LOC is the location of the resulting expression.
8608 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8609 Return the folded expression if folding is successful. Otherwise,
8610 return NULL_TREE. */
8611 static tree
8614 {
8615 tree tem;
8617 /* We only do these simplifications if we are optimizing. */
8621 /* Check for things like (A || B) && (A || C). We can convert this
8622 to A || (B && C). Note that either operator can be any of the four
8623 truth and/or operations and the transformation will still be
8624 valid. Also note that we only care about order for the
8625 ANDIF and ORIF operators. If B contains side effects, this
8626 might change the truth-value of A. */
8633 {
8653 /* This case if tricky because we must either have commutative
8654 operators or else A10 must not have side-effects. */
8660 a01);
8661 }
8663 /* See if we can build a range comparison. */
8669 {
8673 }
8677 {
8681 }
8683 /* Check for the possibility of merging component references. If our
8684 lhs is another similar operation, try to merge its rhs with our
8685 rhs. Then try to merge our lhs and rhs. */
8699 {
8706 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8707 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8708 We don't want to pack more than two leafs to a non-IF AND/OR
8709 expression.
8710 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8711 equal to IF-CODE, then we don't want to add right-hand operand.
8712 If the inner right-hand side of left-hand operand has
8713 side-effects, or isn't simple, then we can't add to it,
8714 as otherwise we might destroy if-sequence. */
8717 /* Needed for sequence points to handle trappings, and
8718 side-effects. */
8720 {
8722 arg1);
8724 tem);
8725 }
8726 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8727 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8730 /* Needed for sequence points to handle trappings, and
8731 side-effects. */
8733 {
8738 }
8739 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8740 into (A OR B).
8741 For sequence point consistancy, we need to check for trapping,
8742 and side-effects. */
8746 }
8749 }
8751 /* Fold a binary expression of code CODE and type TYPE with operands
8752 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8753 Return the folded expression if folding is successful. Otherwise,
8754 return NULL_TREE. */
8756 static tree
8758 {
8765 else
8768 /* MIN (MAX (a, b), b) == b. */
8773 /* MIN (MAX (b, a), b) == b. */
8779 /* MIN (a, MAX (a, b)) == a. */
8785 /* MIN (a, MAX (b, a)) == a. */
8792 }
8794 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8795 by changing CODE to reduce the magnitude of constants involved in
8796 ARG0 of the comparison.
8797 Returns a canonicalized comparison tree if a simplification was
8798 possible, otherwise returns NULL_TREE.
8799 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8800 valid if signed overflow is undefined. */
8802 static tree
8806 {
8812 /* Match A +- CST code arg1 and CST code arg1. We can change the
8813 first form only if overflow is undefined. */
8815 /* In principle pointers also have undefined overflow behavior,
8816 but that causes problems elsewhere. */
8824 /* Identify the constant in arg0 and its sign. */
8827 else
8831 /* Overflowed constants and zero will cause problems. */
8836 /* See if we can reduce the magnitude of the constant in
8837 arg0 by changing the comparison code. */
8839 {
8840 /* CST <= arg1 -> CST-1 < arg1. */
8843 /* -CST < arg1 -> -CST-1 <= arg1. */
8846 /* CST > arg1 -> CST-1 >= arg1. */
8849 /* -CST >= arg1 -> -CST-1 > arg1. */
8852 else
8854 /* arg1 code' CST' might be more canonical. */
8856 }
8857 else
8858 {
8859 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8863 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8867 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8871 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8875 else
8878 }
8880 /* Now build the constant reduced in magnitude. But not if that
8881 would produce one outside of its types range. */
8889 /* We cannot swap the comparison here as that would cause us to
8890 endlessly recurse. */
8899 /* If swapping might yield to a more canonical form, do so. */
8902 else
8904 }
8906 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8907 overflow further. Try to decrease the magnitude of constants involved
8908 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8909 and put sole constants at the second argument position.
8910 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8912 static tree
8915 {
8916 tree t;
8921 /* Try canonicalization by simplifying arg0. */
8926 {
8930 }
8932 /* Try canonicalization by simplifying arg1 using the swapped
8933 comparison. */
8941 }
8943 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8944 space. This is used to avoid issuing overflow warnings for
8945 expressions like &p->x which can not wrap. */
8947 static bool
8949 {
8956 wide_int wi_offset;
8962 else
8978 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8979 array. */
8981 {
8982 HOST_WIDE_INT base_size;
8987 }
8990 }
8992 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8993 kind INTEGER_CST. This makes sure to properly sign-extend the
8994 constant. */
8996 static HOST_WIDE_INT
8998 {
9004 }
9006 /* Subroutine of fold_binary. This routine performs all of the
9007 transformations that are common to the equality/inequality
9008 operators (EQ_EXPR and NE_EXPR) and the ordering operators
9009 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
9010 fold_binary should call fold_binary. Fold a comparison with
9011 tree code CODE and type TYPE with operands OP0 and OP1. Return
9012 the folded comparison or NULL_TREE. */
9014 static tree
9017 {
9031 /* If one arg is a real or integer constant, put it last. */
9035 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
9042 {
9043 const enum tree_code
9050 /* If the constant operation overflowed this can be
9051 simplified as a comparison against INT_MAX/INT_MIN. */
9053 {
9057 /* Get the sign of the constant on the lhs if the
9058 operation were VARIABLE + CONST1. */
9062 /* The sign of the constant determines if we overflowed
9063 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
9064 Canonicalize to the INT_MIN overflow by swapping the comparison
9065 if necessary. */
9069 /* We now can look at the canonicalized case
9070 VARIABLE + 1 CODE2 INT_MIN
9071 and decide on the result. */
9073 {
9077 return
9083 return
9088 }
9089 }
9090 else
9091 {
9094 "when changing X +- C1 cmp C2 to "
9096 WARN_STRICT_OVERFLOW_COMPARISON);
9098 }
9099 }
9101 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
9103 && equality_code
9105 {
9106 /* ??? The transformation is valid for the other operators if overflow
9107 is undefined for the type, but performing it here badly interacts
9108 with the transformation in fold_cond_expr_with_comparison which
9109 attempts to synthetize ABS_EXPR. */
9113 WARN_STRICT_OVERFLOW_COMPARISON);
9116 }
9118 /* For comparisons of pointers we can decompose it to a compile time
9119 comparison of the base objects and the offsets into the object.
9120 This requires at least one operand being an ADDR_EXPR or a
9121 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
9127 {
9134 /* Get base and offset for the access. Strip ADDR_EXPR for
9135 get_inner_reference, but put it back by stripping INDIRECT_REF
9136 off the base object if possible. indirect_baseN will be true
9137 if baseN is not an address but refers to the object itself. */
9140 {
9146 else
9148 }
9150 {
9154 {
9157 }
9160 {
9165 {
9168 }
9169 }
9170 }
9174 {
9180 else
9182 }
9184 {
9188 {
9191 }
9194 {
9199 {
9202 }
9203 }
9204 }
9206 /* A local variable can never be pointed to by
9207 the default SSA name of an incoming parameter. */
9209 && indirect_base0
9212 && !indirect_base1
9217 && indirect_base1
9220 && !indirect_base0
9224 {
9229 }
9230 /* If we have equivalent bases we might be able to simplify. */
9233 {
9234 /* We can fold this expression to a constant if the non-constant
9235 offset parts are equal. */
9244 {
9250 "occur when comparing P +- C1 with "
9252 WARN_STRICT_OVERFLOW_CONDITIONAL);
9255 {
9269 }
9270 }
9271 /* We can simplify the comparison to a comparison of the variable
9272 offset parts if the constant offset parts are equal.
9273 Be careful to use signed sizetype here because otherwise we
9274 mess with array offsets in the wrong way. This is possible
9275 because pointer arithmetic is restricted to retain within an
9276 object and overflow on pointer differences is undefined as of
9277 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
9279 && (equality_code
9282 {
9283 /* By converting to signed sizetype we cover middle-end pointer
9284 arithmetic which operates on unsigned pointer types of size
9285 type size and ARRAY_REF offsets which are properly sign or
9286 zero extended from their type in case it is narrower than
9287 sizetype. */
9290 else
9294 else
9301 "occur when comparing P +- C1 with "
9303 WARN_STRICT_OVERFLOW_COMPARISON);
9306 }
9307 }
9308 /* For non-equal bases we can simplify if they are addresses
9309 of local binding decls or constants. */
9311 /* We know that !operand_equal_p (base0, base1, 0)
9312 because the if condition was false. But make
9313 sure two decls are not the same. */
9327 {
9334 }
9335 /* For equal offsets we can simplify to a comparison of the
9336 base addresses. */
9338 && (indirect_base0
9340 && (indirect_base1
9345 {
9351 }
9352 }
9354 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9355 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9356 the resulting offset is smaller in absolute value than the
9357 original one and has the same sign. */
9365 {
9370 tree cst;
9372 "occur when combining constants around "
9375 /* Put the constant on the side where it doesn't overflow and is
9376 of lower absolute value and of same sign than before. */
9383 {
9386 variable1,
9390 }
9398 {
9404 variable2);
9405 }
9406 }
9408 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9409 signed arithmetic case. That form is created by the compiler
9410 often enough for folding it to be of value. One example is in
9411 computing loop trip counts after Operator Strength Reduction. */
9417 {
9423 /* Handle unfolded multiplication by zero. */
9428 "eliminating multiplication in comparison "
9430 WARN_STRICT_OVERFLOW_COMPARISON);
9432 /* If const1 is negative we swap the sense of the comparison. */
9437 }
9444 {
9452 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9458 /* (-a) CMP (-b) -> b CMP a */
9465 {
9466 REAL_VALUE_TYPE cst;
9469 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9476 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9477 /* a CMP (-0) -> a CMP 0 */
9482 /* x != NaN is always true, other ops are always false. */
9485 {
9488 }
9490 /* Fold comparisons against infinity. */
9493 {
9497 }
9498 }
9500 /* If this is a comparison of a real constant with a PLUS_EXPR
9501 or a MINUS_EXPR of a real constant, we can convert it into a
9502 comparison with a revised real constant as long as no overflow
9503 occurs when unsafe_math_optimizations are enabled. */
9515 /* Likewise, we can simplify a comparison of a real constant with
9516 a MINUS_EXPR whose first operand is also a real constant, i.e.
9517 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9518 floating-point types only if -fassociative-math is set. */
9524 arg1))
9529 /* Fold comparisons against built-in math functions. */
9531 && flag_unsafe_math_optimizations
9533 {
9537 {
9541 }
9542 }
9543 }
9547 {
9548 /* If we are widening one operand of an integer comparison,
9549 see if the other operand is similarly being widened. Perhaps we
9550 can do the comparison in the narrower type. */
9555 /* Or if we are changing signedness. */
9559 }
9561 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9562 constant, we can simplify it. */
9567 {
9571 }
9573 /* Simplify comparison of something with itself. (For IEEE
9574 floating-point, we can only do some of these simplifications.) */
9576 {
9578 {
9593 /* For NE, we can only do this simplification if integer
9594 or we don't honor IEEE floating point NaNs. */
9598 /* ... fall through ... */
9604 }
9605 }
9607 /* If we are comparing an expression that just has comparisons
9608 of two integer values, arithmetic expressions of those comparisons,
9609 and constants, we can simplify it. There are only three cases
9610 to check: the two values can either be equal, the first can be
9611 greater, or the second can be greater. Fold the expression for
9612 those three values. Since each value must be 0 or 1, we have
9613 eight possibilities, each of which corresponds to the constant 0
9614 or 1 or one of the six possible comparisons.
9616 This handles common cases like (a > b) == 0 but also handles
9617 expressions like ((x > y) - (y > x)) > 0, which supposedly
9618 occur in macroized code. */
9621 {
9626 /* Don't handle degenerate cases here; they should already
9627 have been handled anyway. */
9636 {
9640 /* We can't just pass T to eval_subst in case cval1 or cval2
9641 was the same as ARG1. */
9643 tree high_result
9647 arg1);
9648 tree equal_result
9652 arg1);
9653 tree low_result
9657 arg1);
9659 /* All three of these results should be 0 or 1. Confirm they are.
9660 Then use those values to select the proper code to use. */
9665 {
9666 /* Make a 3-bit mask with the high-order bit being the
9667 value for `>', the next for '=', and the low for '<'. */
9671 {
9673 /* Always false. */
9694 /* Always true. */
9696 }
9699 {
9703 }
9705 }
9706 }
9707 }
9709 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9710 into a single range test. */
9718 {
9722 }
9724 /* Fold ~X op ~Y as Y op X. */
9727 {
9733 }
9735 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9738 {
9744 }
9747 }
9750 /* Subroutine of fold_binary. Optimize complex multiplications of the
9751 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9752 argument EXPR represents the expression "z" of type TYPE. */
9754 static tree
9756 {
9761 {
9764 }
9766 {
9769 }
9770 else
9771 {
9775 }
9784 }
9787 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9788 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9789 guarantees that P and N have the same least significant log2(M) bits.
9790 N is not otherwise constrained. In particular, N is not normalized to
9791 0 <= N < M as is common. In general, the precise value of P is unknown.
9792 M is chosen as large as possible such that constant N can be determined.
9794 Returns M and sets *RESIDUE to N.
9796 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9797 account. This is not always possible due to PR 35705.
9798 */
9800 static unsigned HOST_WIDE_INT
9803 {
9810 {
9815 }
9817 {
9825 allow_func_align);
9831 {
9834 }
9836 {
9839 {
9842 /* Compute the greatest power-of-2 divisor of op1. */
9846 /* If align is non-zero and less than *modulus, replace
9847 *modulus with align., If align is 0, then either op1 is 0
9848 or the greatest power-of-2 divisor of op1 doesn't fit in an
9849 unsigned HOST_WIDE_INT. In either case, no additional
9850 constraint is imposed. */
9855 }
9856 }
9857 }
9859 /* If we get here, we were unable to determine anything useful about the
9860 expression. */
9862 }
9864 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9865 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9867 static bool
9869 {
9873 {
9876 }
9878 {
9884 else
9886 }
9887 else
9893 }
9895 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9896 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9897 NULL_TREE otherwise. */
9899 static tree
9901 {
9918 {
9922 }
9925 {
9931 }
9932 else
9934 }
9936 /* Try to fold a pointer difference of type TYPE two address expressions of
9937 array references AREF0 and AREF1 using location LOC. Return a
9938 simplified expression for the difference or NULL_TREE. */
9940 static tree
9943 {
9948 /* If the bases are array references as well, recurse. If the bases
9949 are pointer indirections compute the difference of the pointers.
9950 If the bases are equal, we are set. */
9953 && (base_offset
9961 {
9967 base_offset,
9970 }
9972 }
9974 /* If the real or vector real constant CST of type TYPE has an exact
9975 inverse, return it, else return NULL. */
9977 static tree
9979 {
9980 REAL_VALUE_TYPE r;
9986 {
10002 {
10007 }
10013 }
10014 }
10016 /* Mask out the tz least significant bits of X of type TYPE where
10017 tz is the number of trailing zeroes in Y. */
10018 static wide_int
10020 {
10025 }
10027 /* Return true when T is an address and is known to be nonzero.
10028 For floating point we further ensure that T is not denormal.
10029 Similar logic is present in nonzero_address in rtlanal.h.
10031 If the return value is based on the assumption that signed overflow
10032 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
10033 change *STRICT_OVERFLOW_P. */
10035 static bool
10037 {
10041 /* Doing something useful for floating point would need more work. */
10047 {
10050 strict_overflow_p);
10056 strict_overflow_p);
10064 }
10067 {
10070 strict_overflow_p);
10078 strict_overflow_p);
10093 strict_overflow_p);
10097 strict_overflow_p);
10100 {
10112 }
10116 }
10118 }
10120 /* Return true when T is an address and is known to be nonzero.
10121 Handle warnings about undefined signed overflow. */
10123 static bool
10125 {
10132 "determining that expression is always "
10134 WARN_STRICT_OVERFLOW_MISC);
10136 }
10138 /* Fold a binary expression of code CODE and type TYPE with operands
10139 OP0 and OP1. LOC is the location of the resulting expression.
10140 Return the folded expression if folding is successful. Otherwise,
10141 return NULL_TREE. */
10143 static tree
10146 {
10161 /* Strip any conversions that don't change the mode. This is
10162 safe for every expression, except for a comparison expression
10163 because its signedness is derived from its operands. So, in
10164 the latter case, only strip conversions that don't change the
10165 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
10166 preserved.
10168 Note that this is done as an internal manipulation within the
10169 constant folder, in order to find the simplest representation
10170 of the arguments so that their form can be studied. In any
10171 cases, the appropriate type conversions should be put back in
10172 the tree that will get out of the constant folder. */
10175 {
10178 }
10179 else
10180 {
10183 }
10185 /* Note that TREE_CONSTANT isn't enough: static var addresses are
10186 constant but we can't do arithmetic on them. */
10194 {
10196 {
10197 /* Make sure type and arg0 have the same saturating flag. */
10201 }
10204 else
10208 {
10212 }
10213 }
10215 /* If this is a commutative operation, and ARG0 is a constant, move it
10216 to ARG1 to reduce the number of tests below. */
10221 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
10223 First check for cases where an arithmetic operation is applied to a
10224 compound, conditional, or comparison operation. Push the arithmetic
10225 operation inside the compound or conditional to see if any folding
10226 can then be done. Convert comparison to conditional for this purpose.
10227 The also optimizes non-constant cases that used to be done in
10228 expand_expr.
10230 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
10231 one of the operands is a comparison and the other is a comparison, a
10232 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
10233 code below would make the expression more complex. Change it to a
10234 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
10235 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
10248 {
10252 boolean_type_node,
10260 }
10264 {
10266 {
10271 tem);
10272 }
10275 {
10280 tem);
10281 }
10286 {
10292 }
10297 {
10303 }
10304 }
10307 {
10309 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10312 {
10318 }
10320 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10323 {
10324 tree base;
10325 HOST_WIDE_INT coffset;
10334 }
10339 /* 0 +p index -> (type)index */
10343 /* PTR +p 0 -> PTR */
10347 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10353 arg1),
10355 arg0)));
10357 /* (PTR +p B) +p A -> PTR +p (B + A) */
10359 {
10360 tree inner;
10368 }
10370 /* PTR_CST +p CST -> CST1 */
10375 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
10376 of the array. Loop optimizer sometimes produce this type of
10377 expressions. */
10379 {
10385 }
10390 /* A + (-B) -> A - B */
10397 /* (-A) + B -> B - A */
10407 {
10408 /* Convert ~A + 1 to -A. */
10415 /* ~X + X is -1. */
10418 {
10423 {
10426 }
10427 }
10429 /* X + ~X is -1. */
10432 {
10437 {
10440 }
10441 }
10443 /* X + (X / CST) * -CST is X % CST. */
10448 {
10457 cst0));
10458 }
10459 }
10461 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10462 one. Make sure the type is not saturating and has the signedness of
10463 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10464 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10471 {
10475 }
10478 {
10482 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10483 with a constant, and the two constants have no bits in common,
10484 we should treat this as a BIT_IOR_EXPR since this may produce more
10485 simplifications. */
10492 {
10495 }
10497 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10498 (plus (plus (mult) (mult)) (foo)) so that we can
10499 take advantage of the factoring cases below. */
10507 {
10513 else
10526 parg0),
10528 marg)),
10532 return
10538 parg1)));
10539 }
10540 }
10541 else
10542 {
10543 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10547 /* Likewise if the operands are reversed. */
10551 /* Convert X + -C into X - C. */
10554 {
10560 }
10562 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10563 to __complex__ ( x, y ). This is not the same for SNaNs or
10564 if signed zeros are involved. */
10568 {
10575 {
10579 {
10585 }
10587 {
10593 }
10594 }
10595 }
10603 /* Convert x+x into x*2.0. */
10609 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10610 We associate floats only if the user has specified
10611 -fassociative-math. */
10615 {
10620 {
10621 tree tree0;
10624 }
10625 }
10626 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10627 We associate floats only if the user has specified
10628 -fassociative-math. */
10632 {
10637 {
10638 tree tree0;
10641 }
10642 }
10643 }
10645 bit_rotate:
10646 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10647 is a rotate of A by C1 bits. */
10648 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10649 is a rotate of A by B bits. */
10650 {
10652 tree rtype;
10661 /* Only create rotates in complete modes. Other cases are not
10662 expanded properly. */
10665 {
10679 {
10685 }
10687 {
10695 element_precision
10699 return
10702 ? LROTATE_EXPR
10706 }
10708 {
10716 element_precision
10720 return fold_convert_loc
10723 ? LROTATE_EXPR
10727 }
10728 }
10729 }
10731 associate:
10732 /* In most languages, can't associate operations on floats through
10733 parentheses. Rather than remember where the parentheses were, we
10734 don't associate floats at all, unless the user has specified
10735 -fassociative-math.
10736 And, we need to make sure type is not saturating. */
10740 {
10746 /* Split both trees into variables, constants, and literals. Then
10747 associate each group together, the constants with literals,
10748 then the result with variables. This increases the chances of
10749 literals being recombined later and of generating relocatable
10750 expressions for the sum of a constant and literal. */
10755 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10759 /* With undefined overflow prefer doing association in a type
10760 which wraps on overflow, if that is one of the operand types. */
10763 {
10771 }
10773 /* With undefined overflow we can only associate constants with one
10774 variable, and constants whose association doesn't overflow. */
10777 {
10779 {
10797 /* The only case we can still associate with two variables
10798 is if they are the same, modulo negation and bit-pattern
10799 preserving conversions. */
10802 }
10803 }
10805 /* Only do something if we found more than two objects. Otherwise,
10806 nothing has changed and we risk infinite recursion. */
10812 {
10824 /* Preserve the MINUS_EXPR if the negative part of the literal is
10825 greater than the positive part. Otherwise, the multiplicative
10826 folding code (i.e extract_muldiv) may be fooled in case
10827 unsigned constants are subtracted, like in the following
10828 example: ((X*2 + 4) - 8U)/2. */
10830 {
10834 {
10838 }
10839 else
10840 {
10844 }
10845 }
10847 /* Don't introduce overflows through reassociation. */
10854 {
10856 return
10860 else
10861 {
10864 return
10868 }
10869 }
10872 return
10875 }
10876 }
10881 /* Pointer simplifications for subtraction, simple reassociations. */
10883 {
10884 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10887 {
10897 }
10898 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10900 {
10907 }
10908 }
10909 /* A - (-B) -> A + B */
10914 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10923 /* Convert -A - 1 to ~A. */
10932 /* Convert -1 - A to ~A. */
10938 /* X - (X / Y) * Y is X % Y. */
10946 return
10952 {
10958 /* Fold A - (A & B) into ~B & A. */
10961 {
10963 {
10970 }
10972 {
10979 }
10980 }
10982 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10983 any power of 2 minus 1. */
10988 {
10994 {
10998 }
10999 }
11000 }
11002 /* See if ARG1 is zero and X - ARG1 reduces to X. */
11006 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
11007 ARG0 is zero and X + ARG0 reduces to X, since that would mean
11008 (-ARG1 + ARG0) reduces to -ARG1. */
11012 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
11013 __complex__ ( x, -y ). This is not the same for SNaNs or if
11014 signed zeros are involved. */
11018 {
11025 {
11029 {
11031 arg1r ? arg1r
11036 }
11038 {
11042 arg1i ? arg1i
11045 }
11046 }
11047 }
11049 /* Fold &x - &x. This can happen from &x.foo - &x.
11050 This is unsafe for certain floats even in non-IEEE formats.
11051 In IEEE, it is unsafe because it does wrong for NaNs.
11052 Also note that operand_equal_p is always false if an operand
11053 is volatile. */
11059 /* A - B -> A + (-B) if B is easily negatable. */
11062 /* Avoid this transformation if B is a positive REAL_CST. */
11071 /* Try folding difference of addresses. */
11072 {
11073 HOST_WIDE_INT diff;
11079 }
11081 /* Fold &a[i] - &a[j] to i-j. */
11086 {
11092 }
11095 && flag_unsafe_math_optimizations
11101 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
11102 one. Make sure the type is not saturating and has the signedness of
11103 the stripped operands, as fold_plusminus_mult_expr will re-associate.
11104 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
11111 {
11115 }
11120 /* (-A) * (-B) -> A * B */
11135 {
11140 /* Transform x * -1 into -x. Make sure to do the negation
11141 on the original operand with conversions not stripped
11142 because we can only strip non-sign-changing conversions. */
11145 /* Transform x * -C into -x * C if x is easily negatable. */
11154 tem);
11156 /* (a * (1 << b)) is (a << b) */
11166 /* (A + A) * C -> A * 2 * C */
11178 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
11179 sign-changing only. */
11189 {
11192 "occur when simplifying "
11194 WARN_STRICT_OVERFLOW_MISC);
11196 }
11198 /* Optimize z * conj(z) for integer complex numbers. */
11205 }
11206 else
11207 {
11208 /* Maybe fold x * 0 to 0. The expressions aren't the same
11209 when x is NaN, since x * 0 is also NaN. Nor are they the
11210 same in modes with signed zeros, since multiplying a
11211 negative value by 0 gives -0, not +0. */
11216 /* In IEEE floating point, x*1 is not equivalent to x for snans.
11217 Likewise for complex arithmetic with signed zeros. */
11224 /* Transform x * -1.0 into -x. */
11231 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
11232 the result for floating point types due to rounding so it is applied
11233 only if -fassociative-math was specify. */
11238 {
11240 arg1);
11244 }
11246 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
11248 {
11251 {
11254 }
11255 }
11257 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
11258 This is not the same for NaNs or if signed zeros are
11259 involved. */
11265 {
11268 return
11274 return
11279 }
11281 /* Optimize z * conj(z) for floating point complex numbers.
11282 Guarded by flag_unsafe_math_optimizations as non-finite
11283 imaginary components don't produce scalar results. */
11294 {
11298 /* Optimizations of root(...)*root(...). */
11300 {
11305 /* Optimize sqrt(x)*sqrt(x) as x. */
11311 /* Optimize root(x)*root(y) as root(x*y). */
11315 }
11317 /* Optimize expN(x)*expN(y) as expN(x+y). */
11319 {
11325 }
11327 /* Optimizations of pow(...)*pow(...). */
11331 {
11337 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
11339 {
11344 }
11346 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
11348 {
11353 }
11354 }
11356 /* Optimize tan(x)*cos(x) as sin(x). */
11365 {
11371 }
11373 /* Optimize x*pow(x,c) as pow(x,c+1). */
11377 {
11383 {
11385 REAL_VALUE_TYPE c;
11386 tree arg;
11392 }
11393 }
11395 /* Optimize pow(x,c)*x as pow(x,c+1). */
11399 {
11405 {
11407 REAL_VALUE_TYPE c;
11408 tree arg;
11414 }
11415 }
11417 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
11419 && optimize
11421 {
11425 {
11428 }
11429 }
11430 }
11431 }
11435 bit_ior:
11443 /* ~X | X is -1. */
11446 {
11450 }
11452 /* X | ~X is -1. */
11455 {
11459 }
11461 /* Canonicalize (X & C1) | C2. */
11465 {
11470 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
11478 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
11483 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
11484 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
11485 mode which allows further optimizations. */
11490 {
11494 {
11497 }
11498 }
11505 c3)),
11506 arg1);
11507 }
11509 /* (X & Y) | Y is (X, Y). */
11513 /* (X & Y) | X is (Y, X). */
11518 /* X | (X & Y) is (Y, X). */
11523 /* X | (Y & X) is (Y, X). */
11529 /* (X & ~Y) | (~X & Y) is X ^ Y */
11532 {
11549 }
11555 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11557 This results in more efficient code for machines without a NAND
11558 instruction. Combine will canonicalize to the first form
11559 which will allow use of NAND instructions provided by the
11560 backend if they exist. */
11563 {
11564 return
11571 }
11573 /* See if this can be simplified into a rotate first. If that
11574 is unsuccessful continue in the association code. */
11585 /* ~X ^ X is -1. */
11588 {
11592 }
11594 /* X ^ ~X is -1. */
11597 {
11601 }
11603 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11604 with a constant, and the two constants have no bits in common,
11605 we should treat this as a BIT_IOR_EXPR since this may produce more
11606 simplifications. */
11613 {
11616 }
11618 /* (X | Y) ^ X -> Y & ~ X*/
11621 {
11624 arg1);
11629 }
11631 /* (Y | X) ^ X -> Y & ~ X*/
11634 {
11637 arg1);
11642 }
11644 /* X ^ (X | Y) -> Y & ~ X*/
11647 {
11650 arg0);
11655 }
11657 /* X ^ (Y | X) -> Y & ~ X*/
11660 {
11663 arg0);
11668 }
11670 /* Convert ~X ^ ~Y to X ^ Y. */
11679 /* Convert ~X ^ C to X ^ ~C. */
11687 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11694 /* Fold (X & Y) ^ Y as ~X & Y. */
11697 {
11702 }
11703 /* Fold (X & Y) ^ X as ~Y & X. */
11707 {
11712 }
11713 /* Fold X ^ (X & Y) as X & ~Y. */
11716 {
11721 }
11722 /* Fold X ^ (Y & X) as ~Y & X. */
11726 {
11731 }
11733 /* See if this can be simplified into a rotate first. If that
11734 is unsuccessful continue in the association code. */
11745 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11753 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11761 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
11765 {
11771 return
11775 }
11777 /* (X | Y) & Y is (X, Y). */
11781 /* (X | Y) & X is (Y, X). */
11786 /* X & (X | Y) is (Y, X). */
11791 /* X & (Y | X) is (Y, X). */
11797 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11801 {
11802 tree tem2;
11809 }
11810 /* Fold ~X & 1 as (X & 1) == 0. */
11813 {
11814 tree tem2;
11821 }
11822 /* Fold !X & 1 as X == 0. */
11825 {
11829 }
11831 /* Fold (X ^ Y) & Y as ~X & Y. */
11834 {
11839 }
11840 /* Fold (X ^ Y) & X as ~Y & X. */
11844 {
11849 }
11850 /* Fold X & (X ^ Y) as X & ~Y. */
11853 {
11858 }
11859 /* Fold X & (Y ^ X) as ~Y & X. */
11863 {
11868 }
11870 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11871 multiple of 1 << CST. */
11873 {
11880 }
11882 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11883 bits from CST2. */
11887 {
11895 {
11896 /* Avoid the transform if arg1 is a mask of some
11897 mode which allows further optimizations. */
11904 }
11905 }
11907 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11908 ((A & N) + B) & M -> (A + B) & M
11909 Similarly if (N & M) == 0,
11910 ((A | N) + B) & M -> (A + B) & M
11911 and for - instead of + (or unary - instead of +)
11912 and/or ^ instead of |.
11913 If B is constant and (B & M) == 0, fold into A & M. */
11915 {
11924 {
11927 wide_int cst0;
11929 /* Now we know that arg0 is (C + D) or (C - D) or
11930 -C and arg1 (M) is == (1LL << cst) - 1.
11931 Store C into PMOP[0] and D into PMOP[1]. */
11935 {
11938 }
11945 {
11955 {
11958 }
11961 /* If C or D is of the form (A & N) where
11962 (N & M) == M, or of the form (A | N) or
11963 (A ^ N) where (N & M) == 0, replace it with A. */
11967 /* If C or D is a N where (N & M) == 0, it can be
11968 omitted (assumed 0). */
11976 }
11978 /* Only build anything new if we optimized one or both arguments
11979 above. */
11983 {
11986 {
11987 /* Perform the operations in a type that has defined
11988 overflow behavior. */
11994 }
11999 {
12007 else
12009 }
12012 else
12015 /* TEM is now the new binary +, - or unary - replacement. */
12019 }
12020 }
12021 }
12026 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
12029 {
12034 return
12036 }
12038 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
12040 This results in more efficient code for machines without a NOR
12041 instruction. Combine will canonicalize to the first form
12042 which will allow use of NOR instructions provided by the
12043 backend if they exist. */
12046 {
12053 }
12055 /* If arg0 is derived from the address of an object or function, we may
12056 be able to fold this expression using the object or function's
12057 alignment. */
12059 {
12066 /* This works because modulus is a power of 2. If this weren't the
12067 case, we'd have to replace it by its greatest power-of-2
12068 divisor: modulus & -modulus. */
12071 }
12073 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
12074 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
12075 if the new mask might be further optimized. */
12084 {
12095 {
12098 /* See if more bits can be proven as zero because of
12099 zero extension. */
12102 {
12107 {
12109 /* See if we can shorten the right shift. */
12112 /* Otherwise X >> C1 is all zeros, so we'll optimize
12113 it into (X, 0) later on by making sure zerobits
12114 is all ones. */
12115 }
12116 }
12119 {
12122 }
12123 /* For arithmetic shift if sign bit could be set, zerobits
12124 can contain actually sign bits, so no transformation is
12125 possible, unless MASK masks them all away. In that
12126 case the shift needs to be converted into logical shift. */
12129 {
12132 else
12134 }
12135 }
12137 /* ((X << 16) & 0xff00) is (X, 0). */
12144 {
12145 /* Only do the transformation if NEWMASK is some integer
12146 mode's mask. */
12153 {
12154 tree newmaskt;
12157 {
12163 }
12164 else
12169 }
12170 }
12171 }
12176 /* Don't touch a floating-point divide by zero unless the mode
12177 of the constant can represent infinity. */
12183 /* Optimize A / A to 1.0 if we don't care about
12184 NaNs or Infinities. Skip the transformation
12185 for non-real operands. */
12190 {
12194 }
12196 /* The complex version of the above A / A optimization. */
12199 {
12203 {
12205 /* omit_two_operands will call fold_convert for us. */
12207 }
12208 }
12210 /* (-A) / (-B) -> A / B */
12220 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
12225 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
12231 /* If ARG1 is a constant, we can convert this to a multiply by the
12232 reciprocal. This does not have the same rounding properties,
12233 so only do this if -freciprocal-math. We can actually
12234 always safely do it if ARG1 is a power of two, but it's hard to
12235 tell if it is or not in a portable manner. */
12242 {
12246 /* Find the reciprocal if optimizing and the result is exact.
12247 TODO: Complex reciprocal not implemented. */
12249 {
12254 }
12255 }
12256 /* Convert A/B/C to A/(B*C). */
12263 /* Convert A/(B/C) to (A/B)*C. */
12271 /* Convert C1/(X*C2) into (C1/C2)/X. */
12276 {
12282 }
12285 {
12289 /* Optimize sin(x)/cos(x) as tan(x). */
12295 {
12300 }
12302 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
12308 {
12312 {
12317 }
12318 }
12320 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
12321 NaNs or Infinities. */
12325 {
12332 {
12337 }
12338 }
12340 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
12341 NaNs or Infinities. */
12345 {
12352 {
12356 {
12360 tmp);
12361 }
12362 }
12363 }
12365 /* Optimize pow(x,c)/x as pow(x,c-1). */
12369 {
12375 {
12377 REAL_VALUE_TYPE c;
12378 tree arg;
12384 }
12385 }
12387 /* Optimize a/root(b/c) into a*root(c/b). */
12389 {
12393 {
12402 }
12403 }
12405 /* Optimize x/expN(y) into x*expN(-y). */
12407 {
12414 }
12416 /* Optimize x/pow(y,z) into x*pow(y,-z). */
12420 {
12428 }
12429 }
12433 /* Optimize (X & (-A)) / A where A is a power of 2,
12434 to X >> log2(A) */
12438 {
12446 }
12447 }
12449 /* Fall through */
12452 /* Simplify A / (B << N) where A and B are positive and B is
12453 a power of 2, to A >> (N + log2(B)). */
12458 {
12461 {
12469 WARN_STRICT_OVERFLOW_MISC);
12475 }
12476 }
12478 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
12479 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
12485 /* Fall through */
12494 /* X / -1 is -X. */
12500 /* Convert -A / -B to A / B when the type is signed and overflow is
12501 undefined. */
12505 {
12508 "when distributing negation across "
12510 WARN_STRICT_OVERFLOW_MISC);
12516 }
12520 {
12523 "when distributing negation across "
12525 WARN_STRICT_OVERFLOW_MISC);
12531 }
12533 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
12534 operation, EXACT_DIV_EXPR.
12536 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
12537 At one time others generated faster code, it's not clear if they do
12538 after the last round to changes to the DIV code in expmed.c. */
12547 {
12551 WARN_STRICT_OVERFLOW_MISC);
12553 }
12561 /* X % 1 is always zero, but be sure to preserve any side
12562 effects in X. */
12566 /* X % 0, return X % 0 unchanged so that we can get the
12567 proper warnings and errors. */
12571 /* 0 % X is always zero, but be sure to preserve any side
12572 effects in X. Place this after checking for X == 0. */
12576 /* X % -1 is zero. */
12582 /* X % -C is the same as X % C. */
12589 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
12596 /* X % -Y is the same as X % Y. */
12609 {
12613 WARN_STRICT_OVERFLOW_MISC);
12615 }
12617 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
12618 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
12622 {
12624 /* Also optimize A % (C << N) where C is a power of 2,
12625 to A & ((C << N) - 1). */
12630 {
12631 tree mask
12636 "occur when simplifying "
12638 WARN_STRICT_OVERFLOW_MISC);
12642 }
12643 }
12654 /* Optimize -1 >> x for arithmetic right shifts. */
12658 /* ... fall through ... */
12661 shift:
12667 /* Prefer vector1 << scalar to vector1 << vector2
12668 if vector2 is uniform. */
12673 /* Since negative shift count is not well-defined,
12674 don't try to compute it in the compiler. */
12680 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12685 {
12689 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12690 being well defined. */
12692 {
12698 else
12700 }
12704 }
12706 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12707 into x & ((unsigned)-1 >> c) for unsigned types. */
12715 {
12718 tree lshift;
12719 tree arg00;
12722 {
12729 }
12730 }
12732 /* Rewrite an LROTATE_EXPR by a constant into an
12733 RROTATE_EXPR by a new constant. */
12735 {
12739 }
12741 /* If we have a rotate of a bit operation with the rotate count and
12742 the second operand of the bit operation both constant,
12743 permute the two operations. */
12755 /* Two consecutive rotates adding up to the some integer
12756 multiple of the precision of the type can be ignored. */
12764 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12765 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12766 if the latter can be further optimized. */
12771 {
12775 arg1);
12779 arg1);
12783 }
12811 /* Note that the operands of this must be ints
12812 and their values must be 0 or 1.
12813 ("true" is a fixed value perhaps depending on the language.) */
12814 /* If first arg is constant zero, return it. */
12818 /* If either arg is constant true, drop it. */
12822 /* Preserve sequence points. */
12825 /* If second arg is constant zero, result is zero, but first arg
12826 must be evaluated. */
12829 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12830 case will be handled here. */
12834 /* !X && X is always false. */
12838 /* X && !X is always false. */
12843 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12844 means A >= Y && A != MAX, but in this case we know that
12845 A < X <= MAX. */
12849 {
12857 }
12866 /* Note that the operands of this must be ints
12867 and their values must be 0 or true.
12868 ("true" is a fixed value perhaps depending on the language.) */
12869 /* If first arg is constant true, return it. */
12873 /* If either arg is constant zero, drop it. */
12877 /* Preserve sequence points. */
12880 /* If second arg is constant true, result is true, but we must
12881 evaluate first arg. */
12884 /* Likewise for first arg, but note this only occurs here for
12885 TRUTH_OR_EXPR. */
12889 /* !X || X is always true. */
12893 /* X || !X is always true. */
12898 /* (X && !Y) || (!X && Y) is X ^ Y */
12901 {
12918 }
12927 /* If the second arg is constant zero, drop it. */
12930 /* If the second arg is constant true, this is a logical inversion. */
12932 {
12935 }
12936 /* Identical arguments cancel to zero. */
12940 /* !X ^ X is always true. */
12945 /* X ^ !X is always true. */
12961 /* bool_var != 0 becomes bool_var. */
12966 /* bool_var == 1 becomes bool_var. */
12971 /* bool_var != 1 becomes !bool_var. */
12978 /* bool_var == 0 becomes !bool_var. */
12985 /* !exp != 0 becomes !exp */
12990 /* If this is an equality comparison of the address of two non-weak,
12991 unaliased symbols neither of which are extern (since we do not
12992 have access to attributes for externs), then we know the result. */
13005 {
13006 /* We know that we're looking at the address of two
13007 non-weak, unaliased, static _DECL nodes.
13009 It is both wasteful and incorrect to call operand_equal_p
13010 to compare the two ADDR_EXPR nodes. It is wasteful in that
13011 all we need to do is test pointer equality for the arguments
13012 to the two ADDR_EXPR nodes. It is incorrect to use
13013 operand_equal_p as that function is NOT equivalent to a
13014 C equality test. It can in fact return false for two
13015 objects which would test as equal using the C equality
13016 operator. */
13020 type);
13021 }
13023 /* Similarly for a NEGATE_EXPR. */
13027 arg1)))
13032 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
13040 arg1),
13043 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
13052 {
13056 val,
13060 }
13062 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
13069 {
13071 code == NE_EXPR
13074 }
13076 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
13081 /* If this is an EQ or NE comparison with zero and ARG0 is
13082 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
13083 two operations, but the latter can be done in one less insn
13084 on machines that have only two-operand insns or on which a
13085 constant cannot be the first operand. */
13088 {
13093 {
13100 arg1);
13101 }
13104 {
13111 arg1);
13112 }
13113 }
13115 /* If this is an NE or EQ comparison of zero against the result of a
13116 signed MOD operation whose second operand is a power of 2, make
13117 the MOD operation unsigned since it is simpler and equivalent. */
13125 {
13135 }
13137 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
13138 C1 is a valid shift constant, and C2 is a power of two, i.e.
13139 a single bit. */
13143 == INTEGER_CST
13146 {
13151 /* Check for a valid shift count. */
13153 {
13157 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
13158 can be rewritten as (X & (C2 << C1)) != 0. */
13160 {
13165 }
13166 /* Otherwise, for signed (arithmetic) shifts,
13167 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
13168 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
13172 /* Otherwise, of unsigned (logical) shifts,
13173 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
13174 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
13175 else
13179 arg000);
13180 }
13181 }
13183 /* If we have (A & C) == C where C is a power of 2, convert this into
13184 (A & C) != 0. Similarly for NE_EXPR. */
13190 integer_zero_node));
13192 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
13193 bit, then fold the expression into A < 0 or A >= 0. */
13198 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
13199 Similarly for NE_EXPR. */
13203 {
13207 tree dandnotc
13210 notc);
13214 }
13216 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
13217 Similarly for NE_EXPR. */
13221 {
13223 tree candnotd
13230 }
13232 /* If this is a comparison of a field, we may be able to simplify it. */
13235 /* Handle the constant case even without -O
13236 to make sure the warnings are given. */
13238 {
13242 }
13244 /* Optimize comparisons of strlen vs zero to a compare of the
13245 first character of the string vs zero. To wit,
13246 strlen(ptr) == 0 => *ptr == 0
13247 strlen(ptr) != 0 => *ptr != 0
13248 Other cases should reduce to one of these two (or a constant)
13249 due to the return value of strlen being unsigned. */
13252 {
13260 {
13265 }
13266 }
13268 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
13269 of X. Similarly fold (X >> C) == 0 into X >= 0. */
13273 {
13278 {
13280 {
13283 }
13286 }
13287 }
13289 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
13295 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
13300 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
13307 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
13315 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
13316 (X & C) == 0 when C is a single bit. */
13321 {
13328 arg1));
13329 }
13331 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
13332 constant C is a power of two, i.e. a single bit. */
13339 {
13343 }
13345 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
13346 when is C is a power of two, i.e. a single bit. */
13353 {
13359 }
13363 {
13366 }
13368 /* Fold -X op -Y as X op Y, where op is eq/ne. */
13376 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
13379 {
13392 arg01),
13401 arg01),
13410 arg00),
13419 arg00),
13421 }
13425 {
13432 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
13433 operand_equal_p guarantees no side-effects so we don't need
13434 to use omit_one_operand on Z. */
13438 arg10));
13442 arg11));
13446 arg10));
13450 arg11));
13452 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
13455 {
13461 }
13462 }
13464 /* Attempt to simplify equality/inequality comparisons of complex
13465 values. Only lower the comparison if the result is known or
13466 can be simplified to a single scalar comparison. */
13471 {
13476 {
13479 }
13480 else
13481 {
13484 }
13487 {
13490 }
13491 else
13492 {
13495 }
13499 {
13501 {
13506 }
13507 else
13508 {
13513 }
13514 }
13518 {
13520 {
13525 }
13526 else
13527 {
13532 }
13533 }
13534 }
13546 /* Transform comparisons of the form X +- C CMP X. */
13553 {
13560 else
13563 /* (X - c) > X becomes false. */
13567 {
13571 "occur when assuming that (X - c) > X "
13573 WARN_STRICT_OVERFLOW_ALL);
13575 }
13577 /* Likewise (X + c) < X becomes false. */
13581 {
13585 "occur when assuming that "
13587 WARN_STRICT_OVERFLOW_ALL);
13589 }
13591 /* Convert (X - c) <= X to true. */
13596 {
13600 "occur when assuming that "
13602 WARN_STRICT_OVERFLOW_ALL);
13604 }
13606 /* Convert (X + c) >= X to true. */
13611 {
13615 "occur when assuming that "
13617 WARN_STRICT_OVERFLOW_ALL);
13619 }
13622 {
13623 /* Convert X + c > X and X - c < X to true for integers. */
13627 {
13630 "not occur when assuming that "
13632 WARN_STRICT_OVERFLOW_ALL);
13634 }
13639 {
13642 "not occur when assuming that "
13644 WARN_STRICT_OVERFLOW_ALL);
13646 }
13648 /* Convert X + c <= X and X - c >= X to false for integers. */
13652 {
13655 "not occur when assuming that "
13657 WARN_STRICT_OVERFLOW_ALL);
13659 }
13664 {
13667 "not occur when assuming that "
13669 WARN_STRICT_OVERFLOW_ALL);
13671 }
13672 }
13673 }
13675 /* Comparisons with the highest or lowest possible integer of
13676 the specified precision will have known values. */
13677 {
13683 {
13690 {
13703 /* The GE_EXPR and LT_EXPR cases above are not normally
13704 reached because of previous transformations. */
13708 }
13711 {
13718 arg1);
13724 arg0),
13725 arg1);
13728 }
13731 {
13746 }
13749 {
13756 arg1);
13762 arg0),
13763 arg1);
13766 }
13770 /* We will flip the signedness of the comparison operator
13771 associated with the mode of arg1, so the sign bit is
13772 specified by this mode. Check that arg1 is the signed
13773 max associated with this sign bit. */
13775 /* signed_type does not work on pointer types. */
13777 {
13778 /* The following case also applies to X < signed_max+1
13779 and X >= signed_max+1 because previous transformations. */
13781 {
13787 }
13788 }
13789 }
13790 }
13792 /* If we are comparing an ABS_EXPR with a constant, we can
13793 convert all the cases into explicit comparisons, but they may
13794 well not be faster than doing the ABS and one comparison.
13795 But ABS (X) <= C is a range comparison, which becomes a subtraction
13796 and a comparison, and is probably faster. */
13810 /* Convert ABS_EXPR<x> >= 0 to true. */
13817 {
13820 "when simplifying comparison of "
13822 WARN_STRICT_OVERFLOW_CONDITIONAL);
13825 arg0);
13826 }
13828 /* Convert ABS_EXPR<x> < 0 to false. */
13833 {
13836 "when simplifying comparison of "
13838 WARN_STRICT_OVERFLOW_CONDITIONAL);
13841 arg0);
13842 }
13844 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13845 and similarly for >= into !=. */
13855 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13856 otherwise Y might be >= # of bits in X's type and thus e.g.
13857 (unsigned char) (1 << Y) for Y 15 might be 0.
13858 If the cast is widening, then 1 << Y should have unsigned type,
13859 otherwise if Y is number of bits in the signed shift type minus 1,
13860 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13861 31 might be 0xffffffff80000000. */
13872 {
13878 }
13891 {
13895 }
13897 /* If the first operand is NaN, the result is constant. */
13901 {
13903 ? integer_zero_node
13906 }
13908 /* If the second operand is NaN, the result is constant. */
13912 {
13914 ? integer_zero_node
13917 }
13919 /* Simplify unordered comparison of something with itself. */
13925 && !flag_trapping_math
13929 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13930 {
13942 }
13947 /* When pedantic, a compound expression can be neither an lvalue
13948 nor an integer constant expression. */
13951 /* Don't let (0, 0) be null pointer constant. */
13972 /* An ASSERT_EXPR should never be passed to fold_binary. */
13977 {
13992 {
13998 }
14001 }
14007 {
14032 {
14045 }
14048 }
14053 }
14055 /* Fold a binary expression of code CODE and type TYPE with operands
14056 OP0 and OP1. Return the folded expression if folding is
14057 successful. Otherwise, return NULL_TREE.
14058 This is a wrapper around fold_binary_1 function (which does the
14059 actual folding). Set the EXPR_FOLDED flag of the folded expression
14060 if folding is successful. */
14061 tree
14064 {
14067 }
14069 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
14070 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
14071 of GOTO_EXPR. */
14073 static tree
14075 {
14077 {
14084 /* ... fall through ... */
14088 }
14089 }
14091 /* Return whether the sub-tree ST contains a label which is accessible from
14092 outside the sub-tree. */
14094 static bool
14096 {
14097 return
14099 }
14101 /* Fold a ternary expression of code CODE and type TYPE with operands
14102 OP0, OP1, and OP2. Return the folded expression if folding is
14103 successful. Otherwise, return NULL_TREE. */
14105 static tree
14108 {
14109 tree tem;
14116 /* Strip any conversions that don't change the mode. This is safe
14117 for every expression, except for a comparison expression because
14118 its signedness is derived from its operands. So, in the latter
14119 case, only strip conversions that don't change the signedness.
14121 Note that this is done as an internal manipulation within the
14122 constant folder, in order to find the simplest representation of
14123 the arguments so that their form can be studied. In any cases,
14124 the appropriate type conversions should be put back in the tree
14125 that will get out of the constant folder. */
14127 {
14130 }
14133 {
14136 }
14139 {
14142 }
14145 {
14149 {
14155 }
14160 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
14161 so all simple results must be passed through pedantic_non_lvalue. */
14163 {
14166 /* Only optimize constant conditions when the selected branch
14167 has the same type as the COND_EXPR. This avoids optimizing
14168 away "c ? x : throw", where the throw has a void type.
14169 Avoid throwing away that operand which contains label. */
14176 }
14178 {
14188 {
14193 {
14201 }
14205 }
14206 }
14211 /* If we have A op B ? A : C, we may be able to convert this to a
14212 simpler expression, depending on the operation and the values
14213 of B and C. Signed zeros prevent all of these transformations,
14214 for reasons given above each one.
14216 Also try swapping the arguments and inverting the conditional. */
14221 {
14225 }
14229 op2,
14232 {
14236 {
14240 }
14241 }
14243 /* If the second operand is simpler than the third, swap them
14244 since that produces better jump optimization results. */
14247 {
14249 /* See if this can be inverted. If it can't, possibly because
14250 it was a floating-point inequality comparison, don't do
14251 anything. */
14255 }
14257 /* Convert A ? 1 : 0 to simply A. */
14262 /* If we try to convert OP0 to our type, the
14263 call to fold will try to move the conversion inside
14264 a COND, which will recurse. In that case, the COND_EXPR
14265 is probably the best choice, so leave it alone. */
14269 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
14270 over COND_EXPR in cases such as floating point comparisons. */
14279 arg0)));
14281 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
14286 {
14287 /* sign_bit_p looks through both zero and sign extensions,
14288 but for this optimization only sign extensions are
14289 usable. */
14292 {
14295 {
14298 }
14300 }
14301 /* sign_bit_p only checks ARG1 bits within A's precision.
14302 If <sign bit of A> has wider type than A, bits outside
14303 of A's precision in <sign bit of A> need to be checked.
14304 If they are all 0, this optimization needs to be done
14305 in unsigned A's type, if they are all 1 in signed A's type,
14306 otherwise this can't be done. */
14312 {
14314 tree tem_type;
14327 {
14330 }
14332 {
14335 }
14336 else
14338 }
14341 return
14347 arg1)));
14348 }
14350 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
14351 already handled above. */
14356 {
14365 }
14367 /* A & N ? N : 0 is simply A & N if N is a power of two. This
14368 is probably obsolete because the first operand should be a
14369 truth value (that's why we have the two cases above), but let's
14370 leave it in until we can confirm this for all front-ends. */
14382 /* Disable the transformations below for vectors, since
14383 fold_binary_op_with_conditional_arg may undo them immediately,
14384 yielding an infinite loop. */
14388 /* Convert A ? B : 0 into A && B if A and B are truth values. */
14397 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
14402 {
14404 /* Only perform transformation if ARG0 is easily inverted. */
14408 ? BIT_IOR_EXPR
14411 arg1);
14412 }
14414 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
14419 {
14421 /* Only perform transformation if ARG0 is easily inverted. */
14427 op2);
14428 }
14430 /* Convert A ? 1 : B into A || B if A and B are truth values. */
14442 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
14443 of fold_ternary on them. */
14453 {
14463 {
14468 {
14476 }
14478 /* Constructor elements can be subvectors. */
14481 {
14485 }
14487 /* We keep an exact subset of the constructor elements. */
14489 {
14495 {
14499 }
14507 CONSTRUCTOR_ELT
14510 }
14511 /* The bitfield references a single constructor element. */
14513 {
14518 else
14522 }
14523 }
14524 }
14526 /* A bit-field-ref that referenced the full argument can be stripped. */
14532 /* On constants we can use native encode/interpret to constant
14533 fold (nearly) all BIT_FIELD_REFs. */
14537 /* This limitation should not be necessary, we just need to
14538 round this up to mode size. */
14540 /* Need bit-shifting of the buffer to relax the following. */
14542 {
14547 /* ??? We cannot tell native_encode_expr to start at
14548 some random byte only. So limit us to a reasonable amount
14549 of work. */
14551 {
14556 {
14562 }
14563 }
14564 }
14569 /* For integers we can decompose the FMA if possible. */
14581 {
14594 {
14599 /* Make sure that the perm value is in an acceptable
14600 range. */
14603 {
14606 }
14607 else
14612 else
14617 }
14620 {
14625 }
14630 {
14635 }
14641 {
14645 }
14651 {
14658 }
14662 }
14668 }
14670 /* Fold a ternary expression of code CODE and type TYPE with operands
14671 OP0, OP1, and OP2. Return the folded expression if folding is
14672 successful. Otherwise, return NULL_TREE.
14673 This is a wrapper around fold_ternary_1 function (which does the
14674 actual folding). Set the EXPR_FOLDED flag of the folded expression
14675 if folding is successful. */
14677 tree
14680 {
14683 }
14685 /* Perform constant folding and related simplification of EXPR.
14686 The related simplifications include x*1 => x, x*0 => 0, etc.,
14687 and application of the associative law.
14688 NOP_EXPR conversions may be removed freely (as long as we
14689 are careful not to change the type of the overall expression).
14690 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14691 but we can constant-fold them if they have constant operands. */
14693 #ifdef ENABLE_FOLD_CHECKING
14694 # define fold(x) fold_1 (x)
14696 static
14697 #endif
14698 tree
14700 {
14704 tree tem;
14707 /* Return right away if a constant. */
14711 /* CALL_EXPR-like objects with variable numbers of operands are
14712 treated specially. */
14714 {
14716 {
14719 }
14721 }
14724 {
14729 {
14747 }
14748 }
14751 {
14753 {
14760 {
14765 /* Find a matching index by means of a binary search. */
14767 {
14783 else
14785 }
14786 }
14789 }
14791 /* Return a VECTOR_CST if possible. */
14793 {
14800 tree value;
14803 {
14807 {
14810 }
14811 else
14813 }
14818 }
14826 }
14828 #ifdef ENABLE_FOLD_CHECKING
14829 #undef fold
14836 /* When --enable-checking=fold, compute a digest of expr before
14837 and after actual fold call to see if fold did not accidentally
14838 change original expr. */
14840 tree
14842 {
14843 tree ret;
14863 }
14865 void
14867 {
14878 }
14880 static void
14882 {
14884 }
14886 static void
14889 {
14895 recursive_label:
14905 {
14906 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14910 }
14917 {
14918 /* Allow these fields to be modified. */
14919 tree tmp;
14927 {
14930 }
14931 }
14942 {
14945 {
14960 }
14964 {
14977 }
14994 {
15000 }
15003 {
15005 {
15008 }
15010 }
15021 {
15024 }
15034 }
15035 }
15037 /* Helper function for outputting the checksum of a tree T. When
15038 debugging with gdb, you can "define mynext" to be "next" followed
15039 by "call debug_fold_checksum (op0)", then just trace down till the
15040 outputs differ. */
15042 DEBUG_FUNCTION void
15044 {
15059 }
15061 #endif
15063 /* Fold a unary tree expression with code CODE of type TYPE with an
15064 operand OP0. LOC is the location of the resulting expression.
15065 Return a folded expression if successful. Otherwise, return a tree
15066 expression with code CODE of type TYPE with an operand OP0. */
15068 tree
15071 {
15072 tree tem;
15073 #ifdef ENABLE_FOLD_CHECKING
15082 #endif
15088 #ifdef ENABLE_FOLD_CHECKING
15095 #endif
15097 }
15099 /* Fold a binary tree expression with code CODE of type TYPE with
15100 operands OP0 and OP1. LOC is the location of the resulting
15101 expression. Return a folded expression if successful. Otherwise,
15102 return a tree expression with code CODE of type TYPE with operands
15103 OP0 and OP1. */
15105 tree
15108 MEM_STAT_DECL)
15109 {
15110 tree tem;
15111 #ifdef ENABLE_FOLD_CHECKING
15128 #endif
15134 #ifdef ENABLE_FOLD_CHECKING
15149 #endif
15151 }
15153 /* Fold a ternary tree expression with code CODE of type TYPE with
15154 operands OP0, OP1, and OP2. Return a folded expression if
15155 successful. Otherwise, return a tree expression with code CODE of
15156 type TYPE with operands OP0, OP1, and OP2. */
15158 tree
15161 {
15162 tree tem;
15163 #ifdef ENABLE_FOLD_CHECKING
15187 #endif
15194 #ifdef ENABLE_FOLD_CHECKING
15217 #endif
15219 }
15221 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
15222 arguments in ARGARRAY, and a null static chain.
15223 Return a folded expression if successful. Otherwise, return a CALL_EXPR
15224 of type TYPE from the given operands as constructed by build_call_array. */
15226 tree
15229 {
15230 tree tem;
15231 #ifdef ENABLE_FOLD_CHECKING
15250 #endif
15254 #ifdef ENABLE_FOLD_CHECKING
15270 #endif
15272 }
15274 /* Perform constant folding and related simplification of initializer
15275 expression EXPR. These behave identically to "fold_buildN" but ignore
15276 potential run-time traps and exceptions that fold must preserve. */
15278 #define START_FOLD_INIT \
15279 int saved_signaling_nans = flag_signaling_nans;\
15280 int saved_trapping_math = flag_trapping_math;\
15281 int saved_rounding_math = flag_rounding_math;\
15282 int saved_trapv = flag_trapv;\
15283 int saved_folding_initializer = folding_initializer;\
15284 flag_signaling_nans = 0;\
15285 flag_trapping_math = 0;\
15286 flag_rounding_math = 0;\
15287 flag_trapv = 0;\
15288 folding_initializer = 1;
15290 #define END_FOLD_INIT \
15291 flag_signaling_nans = saved_signaling_nans;\
15292 flag_trapping_math = saved_trapping_math;\
15293 flag_rounding_math = saved_rounding_math;\
15294 flag_trapv = saved_trapv;\
15295 folding_initializer = saved_folding_initializer;
15297 tree
15300 {
15301 tree result;
15302 START_FOLD_INIT;
15306 END_FOLD_INIT;
15308 }
15310 tree
15313 {
15314 tree result;
15315 START_FOLD_INIT;
15319 END_FOLD_INIT;
15321 }
15323 tree
15326 {
15327 tree result;
15328 START_FOLD_INIT;
15332 END_FOLD_INIT;
15334 }
15336 #undef START_FOLD_INIT
15337 #undef END_FOLD_INIT
15339 /* Determine if first argument is a multiple of second argument. Return 0 if
15340 it is not, or we cannot easily determined it to be.
15342 An example of the sort of thing we care about (at this point; this routine
15343 could surely be made more general, and expanded to do what the *_DIV_EXPR's
15344 fold cases do now) is discovering that
15346 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
15348 is a multiple of
15350 SAVE_EXPR (J * 8)
15352 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
15354 This code also handles discovering that
15356 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
15358 is a multiple of 8 so we don't have to worry about dealing with a
15359 possible remainder.
15361 Note that we *look* inside a SAVE_EXPR only to determine how it was
15362 calculated; it is not safe for fold to do much of anything else with the
15363 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
15364 at run time. For example, the latter example above *cannot* be implemented
15365 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
15366 evaluation time of the original SAVE_EXPR is not necessarily the same at
15367 the time the new expression is evaluated. The only optimization of this
15368 sort that would be valid is changing
15370 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
15372 divided by 8 to
15374 SAVE_EXPR (I) * SAVE_EXPR (J)
15376 (where the same SAVE_EXPR (J) is used in the original and the
15377 transformed version). */
15379 int
15381 {
15389 {
15391 /* Bitwise and provides a power of two multiple. If the mask is
15392 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
15395 /* FALLTHRU */
15408 {
15412 /* const_binop may not detect overflow correctly,
15413 so check for it explicitly here. */
15417 size_one_node,
15418 op1)))
15421 }
15425 /* Can't handle conversions from non-integral or wider integral type. */
15431 /* .. fall through ... */
15448 SIGNED);
15452 }
15453 }
15455 /* Return true if CODE or TYPE is known to be non-negative. */
15457 static bool
15459 {
15462 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
15463 have a signed:1 type (where the value is -1 and 0). */
15466 }
15468 /* Return true if (CODE OP0) is known to be non-negative. If the return
15469 value is based on the assumption that signed overflow is undefined,
15470 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15471 *STRICT_OVERFLOW_P. */
15473 bool
15476 {
15481 {
15483 /* We can't return 1 if flag_wrapv is set because
15484 ABS_EXPR<INT_MIN> = INT_MIN. */
15488 {
15491 }
15498 strict_overflow_p);
15501 {
15506 {
15509 strict_overflow_p);
15511 {
15515 strict_overflow_p);
15516 }
15517 }
15519 {
15522 strict_overflow_p);
15526 }
15527 }
15532 }
15534 /* We don't know sign of `t', so be conservative and return false. */
15536 }
15538 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
15539 value is based on the assumption that signed overflow is undefined,
15540 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15541 *STRICT_OVERFLOW_P. */
15543 bool
15546 {
15551 {
15556 strict_overflow_p)
15558 strict_overflow_p));
15560 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
15561 both unsigned and at least 2 bits shorter than the result. */
15565 {
15570 {
15574 }
15575 }
15580 {
15581 /* x * x is always non-negative for floating point x
15582 or without overflow. */
15586 {
15590 }
15591 }
15593 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
15594 both unsigned and their total bits is shorter than the result. */
15598 {
15617 {
15627 }
15628 }
15634 strict_overflow_p)
15636 strict_overflow_p));
15647 strict_overflow_p)
15649 strict_overflow_p));
15656 strict_overflow_p);
15659 }
15661 /* We don't know sign of `t', so be conservative and return false. */
15663 }
15665 /* Return true if T is known to be non-negative. If the return
15666 value is based on the assumption that signed overflow is undefined,
15667 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15668 *STRICT_OVERFLOW_P. */
15670 bool
15672 {
15677 {
15689 strict_overflow_p)
15691 strict_overflow_p));
15695 }
15696 /* We don't know sign of `t', so be conservative and return false. */
15698 }
15700 /* Return true if T is known to be non-negative. If the return
15701 value is based on the assumption that signed overflow is undefined,
15702 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15703 *STRICT_OVERFLOW_P. */
15705 bool
15708 {
15711 {
15731 /* Always true. */
15735 /* sqrt(-0.0) is -0.0. */
15739 strict_overflow_p);
15776 /* True if the 1st argument is nonnegative. */
15778 strict_overflow_p);
15781 /* True if the 1st OR 2nd arguments are nonnegative. */
15783 strict_overflow_p)
15785 strict_overflow_p)));
15788 /* True if the 1st AND 2nd arguments are nonnegative. */
15790 strict_overflow_p)
15792 strict_overflow_p)));
15795 /* True if the 2nd argument is nonnegative. */
15797 strict_overflow_p);
15800 /* True if the 1st argument is nonnegative or the second
15801 argument is an even integer. */
15806 strict_overflow_p);
15809 /* True if the 1st argument is nonnegative or the second
15810 argument is an even integer valued real. */
15812 {
15813 REAL_VALUE_TYPE c;
15814 HOST_WIDE_INT n;
15819 {
15820 REAL_VALUE_TYPE cint;
15824 }
15825 }
15827 strict_overflow_p);
15831 }
15833 type);
15834 }
15836 /* Return true if T is known to be non-negative. If the return
15837 value is based on the assumption that signed overflow is undefined,
15838 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15839 *STRICT_OVERFLOW_P. */
15841 static bool
15843 {
15849 {
15851 {
15855 /* If the initializer is non-void, then it's a normal expression
15856 that will be assigned to the slot. */
15860 /* Otherwise, the initializer sets the slot in some way. One common
15861 way is an assignment statement at the end of the initializer. */
15863 {
15871 else
15873 }
15877 strict_overflow_p);
15880 }
15883 {
15889 arg0,
15890 arg1,
15891 strict_overflow_p);
15892 }
15896 strict_overflow_p);
15899 strict_overflow_p);
15902 strict_overflow_p);
15907 }
15909 /* We don't know sign of `t', so be conservative and return false. */
15911 }
15913 /* Return true if T is known to be non-negative. If the return
15914 value is based on the assumption that signed overflow is undefined,
15915 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15916 *STRICT_OVERFLOW_P. */
15918 bool
15920 {
15927 {
15934 strict_overflow_p);
15940 strict_overflow_p);
15949 }
15952 {
15960 strict_overflow_p);
15965 strict_overflow_p);
15978 }
15979 }
15981 /* Return true if `t' is known to be non-negative. Handle warnings
15982 about undefined signed overflow. */
15984 bool
15986 {
15993 "determining that expression is always "
15995 WARN_STRICT_OVERFLOW_MISC);
15997 }
16000 /* Return true when (CODE OP0) is an address and is known to be nonzero.
16001 For floating point we further ensure that T is not denormal.
16002 Similar logic is present in nonzero_address in rtlanal.h.
16004 If the return value is based on the assumption that signed overflow
16005 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
16006 change *STRICT_OVERFLOW_P. */
16008 bool
16011 {
16013 {
16016 strict_overflow_p);
16019 {
16025 strict_overflow_p));
16026 }
16031 strict_overflow_p);
16035 }
16038 }
16040 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
16041 For floating point we further ensure that T is not denormal.
16042 Similar logic is present in nonzero_address in rtlanal.h.
16044 If the return value is based on the assumption that signed overflow
16045 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
16046 change *STRICT_OVERFLOW_P. */
16048 bool
16050 tree type,
16051 tree op0,
16053 {
16056 {
16060 {
16061 /* With the presence of negative values it is hard
16062 to say something. */
16069 /* One of operands must be positive and the other non-negative. */
16070 /* We don't set *STRICT_OVERFLOW_P here: even if this value
16071 overflows, on a twos-complement machine the sum of two
16072 nonnegative numbers can never be zero. */
16074 strict_overflow_p)
16076 strict_overflow_p));
16077 }
16082 {
16084 strict_overflow_p)
16086 strict_overflow_p))
16087 {
16090 }
16091 }
16100 {
16103 }
16110 {
16114 /* When both operands are nonzero, then MAX must be too. */
16116 strict_overflow_p))
16119 /* MAX where operand 0 is positive is positive. */
16121 strict_overflow_p);
16122 }
16123 /* MAX where operand 1 is positive is positive. */
16128 {
16132 }
16137 strict_overflow_p)
16139 strict_overflow_p));
16143 }
16146 }
16148 /* Return true when T is an address and is known to be nonzero.
16149 For floating point we further ensure that T is not denormal.
16150 Similar logic is present in nonzero_address in rtlanal.h.
16152 If the return value is based on the assumption that signed overflow
16153 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
16154 change *STRICT_OVERFLOW_P. */
16156 bool
16158 {
16161 {
16166 {
16175 /* For objects in symbol table check if we know they are non-zero.
16176 Don't do anything for variables and functions before symtab is built;
16177 it is quite possible that they will be declared weak later. */
16179 {
16185 else
16187 }
16189 /* Function local objects are never NULL. */
16196 /* Constants are never weak. */
16201 }
16209 {
16213 }
16218 }
16220 }
16222 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
16223 attempt to fold the expression to a constant without modifying TYPE,
16224 OP0 or OP1.
16226 If the expression could be simplified to a constant, then return
16227 the constant. If the expression would not be simplified to a
16228 constant, then return NULL_TREE. */
16230 tree
16232 {
16235 }
16237 /* Given the components of a unary expression CODE, TYPE and OP0,
16238 attempt to fold the expression to a constant without modifying
16239 TYPE or OP0.
16241 If the expression could be simplified to a constant, then return
16242 the constant. If the expression would not be simplified to a
16243 constant, then return NULL_TREE. */
16245 tree
16247 {
16250 }
16252 /* If EXP represents referencing an element in a constant string
16253 (either via pointer arithmetic or array indexing), return the
16254 tree representing the value accessed, otherwise return NULL. */
16256 tree
16258 {
16262 {
16264 tree index;
16265 tree string;
16270 else
16271 {
16275 /* Optimize the special-case of a zero lower bound.
16277 We convert the low_bound to sizetype to avoid some problems
16278 with constant folding. (E.g. suppose the lower bound is 1,
16279 and its mode is QI. Without the conversion,l (ARRAY
16280 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
16281 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
16287 }
16300 }
16302 }
16304 /* Return the tree for neg (ARG0) when ARG0 is known to be either
16305 an integer constant, real, or fixed-point constant.
16307 TYPE is the type of the result. */
16309 static tree
16311 {
16315 {
16317 {
16324 }
16331 {
16332 FIXED_VALUE_TYPE f;
16337 /* Propagate overflow flags. */
16341 }
16345 }
16348 }
16350 /* Return the tree for abs (ARG0) when ARG0 is known to be either
16351 an integer constant or real constant.
16353 TYPE is the type of the result. */
16355 tree
16357 {
16361 {
16363 {
16364 /* If the value is unsigned or non-negative, then the absolute value
16365 is the same as the ordinary value. */
16369 /* If the value is negative, then the absolute value is
16370 its negation. */
16371 else
16372 {
16377 }
16378 }
16384 else
16390 }
16393 }
16395 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
16396 constant. TYPE is the type of the result. */
16398 static tree
16400 {
16404 }
16406 /* Given CODE, a relational operator, the target type, TYPE and two
16407 constant operands OP0 and OP1, return the result of the
16408 relational operation. If the result is not a compile time
16409 constant, then return NULL_TREE. */
16411 static tree
16413 {
16416 /* From here on, the only cases we handle are when the result is
16417 known to be a constant. */
16420 {
16424 /* Handle the cases where either operand is a NaN. */
16426 {
16428 {
16456 }
16459 }
16462 }
16465 {
16469 }
16471 /* Handle equality/inequality of complex constants. */
16473 {
16484 else
16486 }
16489 {
16496 {
16508 }
16511 }
16513 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
16515 To compute GT, swap the arguments and do LT.
16516 To compute GE, do LT and invert the result.
16517 To compute LE, swap the arguments, do LT and invert the result.
16518 To compute NE, do EQ and invert the result.
16520 Therefore, the code below must handle only EQ and LT. */
16523 {
16528 }
16530 /* Note that it is safe to invert for real values here because we
16531 have already handled the one case that it matters. */
16535 {
16538 }
16540 /* Compute a result for LT or EQ if args permit;
16541 Otherwise return T. */
16543 {
16546 else
16548 }
16549 else
16555 }
16557 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
16558 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
16559 itself. */
16561 tree
16563 {
16564 /* If the expression does not have side effects then we don't have to wrap
16565 it with a cleanup point expression. */
16569 /* If the expression is a return, check to see if the expression inside the
16570 return has no side effects or the right hand side of the modify expression
16571 inside the return. If either don't have side effects set we don't need to
16572 wrap the expression in a cleanup point expression. Note we don't check the
16573 left hand side of the modify because it should always be a return decl. */
16575 {
16582 }
16585 }
16587 /* Given a pointer value OP0 and a type TYPE, return a simplified version
16588 of an indirection through OP0, or NULL_TREE if no simplification is
16589 possible. */
16591 tree
16593 {
16595 tree subtype;
16603 {
16606 /* *&CONST_DECL -> to the value of the const decl. */
16609 /* *&p => p; make sure to handle *&"str"[cst] here. */
16611 {
16615 else
16617 }
16618 /* *(foo *)&fooarray => fooarray[0] */
16621 && (!in_gimple_form
16623 {
16633 }
16634 /* *(foo *)&complexfoo => __real__ complexfoo */
16638 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
16641 {
16645 }
16646 }
16650 {
16656 {
16657 tree op00type;
16661 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16664 {
16676 }
16677 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16680 {
16684 }
16685 /* ((foo *)&fooarray)[1] => fooarray[1] */
16688 {
16698 }
16699 }
16700 }
16702 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16705 && (!in_gimple_form
16707 {
16708 tree type_domain;
16718 NULL_TREE);
16719 }
16722 }
16724 /* Builds an expression for an indirection through T, simplifying some
16725 cases. */
16727 tree
16729 {
16737 }
16739 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16741 tree
16743 {
16748 else
16750 }
16752 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16753 whose result is ignored. The type of the returned tree need not be
16754 the same as the original expression. */
16756 tree
16758 {
16764 {
16775 else
16781 {
16797 }
16802 }
16803 }
16805 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16807 tree
16809 {
16815 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16816 have to do anything. Only do this when we are not given a const,
16817 because in that case, this check is more expensive than just
16818 doing it. */
16820 {
16825 }
16827 /* If divisor is a power of two, simplify this to bit manipulation. */
16829 {
16831 {
16845 }
16846 else
16847 {
16848 tree t;
16854 }
16855 }
16856 else
16857 {
16862 }
16865 }
16867 /* Likewise, but round down. */
16869 tree
16871 {
16878 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16879 have to do anything. Only do this when we are not given a const,
16880 because in that case, this check is more expensive than just
16881 doing it. */
16883 {
16888 }
16890 /* If divisor is a power of two, simplify this to bit manipulation. */
16892 {
16893 tree t;
16897 }
16898 else
16899 {
16904 }
16907 }
16909 /* Returns the pointer to the base of the object addressed by EXP and
16910 extracts the information about the offset of the access, storing it
16911 to PBITPOS and POFFSET. */
16913 static tree
16916 {
16917 tree core;
16920 HOST_WIDE_INT bitsize;
16924 {
16929 }
16930 else
16931 {
16935 }
16938 }
16940 /* Returns true if addresses of E1 and E2 differ by a constant, false
16941 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16943 bool
16945 {
16959 {
16969 }
16971 {
16972 /* If only one of the offsets is non-constant, the difference cannot
16973 be a constant. */
16975 }
16976 else
16981 }
16983 /* Simplify the floating point expression EXP when the sign of the
16984 result is not significant. Return NULL_TREE if no simplification
16985 is possible. */
16987 tree
16989 {
16994 {
17030 {
17033 {
17035 /* Strip copysign function call, return the 1st argument. */
17041 /* Strip sign ops from the argument of "odd" math functions. */
17043 {
17047 }
17049 }
17050 }
17055 }
17057 }