| blob | a711be9c1064cb40c6c4da9a1b1e4c9e4245afe4 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
130 HOST_WIDE_INT *,
161 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
162 Otherwise, return LOC. */
164 static location_t
166 {
169 }
171 /* Similar to protected_set_expr_location, but never modify x in place,
172 if location can and needs to be set, unshare it. */
176 {
182 {
185 }
187 }
188 \f
189 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
190 division and returns the quotient. Otherwise returns
191 NULL_TREE. */
193 tree
195 {
196 widest_int quo;
203 }
204 \f
205 /* This is nonzero if we should defer warnings about undefined
206 overflow. This facility exists because these warnings are a
207 special case. The code to estimate loop iterations does not want
208 to issue any warnings, since it works with expressions which do not
209 occur in user code. Various bits of cleanup code call fold(), but
210 only use the result if it has certain characteristics (e.g., is a
211 constant); that code only wants to issue a warning if the result is
212 used. */
216 /* If a warning about undefined overflow is deferred, this is the
217 warning. Note that this may cause us to turn two warnings into
218 one, but that is fine since it is sufficient to only give one
219 warning per expression. */
223 /* If a warning about undefined overflow is deferred, this is the
224 level at which the warning should be emitted. */
228 /* Start deferring overflow warnings. We could use a stack here to
229 permit nested calls, but at present it is not necessary. */
231 void
233 {
235 }
237 /* Stop deferring overflow warnings. If there is a pending warning,
238 and ISSUE is true, then issue the warning if appropriate. STMT is
239 the statement with which the warning should be associated (used for
240 location information); STMT may be NULL. CODE is the level of the
241 warning--a warn_strict_overflow_code value. This function will use
242 the smaller of CODE and the deferred code when deciding whether to
243 issue the warning. CODE may be zero to mean to always use the
244 deferred code. */
246 void
248 {
250 location_t locus;
255 {
261 }
272 /* Use the smallest code level when deciding to issue the
273 warning. */
282 else
285 }
287 /* Stop deferring overflow warnings, ignoring any deferred
288 warnings. */
290 void
292 {
294 }
296 /* Whether we are deferring overflow warnings. */
298 bool
300 {
302 }
304 /* This is called when we fold something based on the fact that signed
305 overflow is undefined. */
307 static void
309 {
311 {
314 {
317 }
318 }
321 }
322 \f
323 /* Return true if the built-in mathematical function specified by CODE
324 is odd, i.e. -f(x) == f(-x). */
326 static bool
328 {
330 {
364 }
366 }
368 /* Check whether we may negate an integer constant T without causing
369 overflow. */
371 bool
373 {
374 tree type;
383 }
385 /* Determine whether an expression T can be cheaply negated using
386 the function negate_expr without introducing undefined overflow. */
388 static bool
390 {
391 tree type;
400 {
405 /* Check that -CST will not overflow type. */
416 /* We want to canonicalize to positive real constants. Pretend
417 that only negative ones can be easily negated. */
425 {
436 }
449 /* -(A + B) -> (-B) - A. */
454 /* -(A + B) -> (-A) - B. */
458 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
468 /* Fall through. */
479 /* In general we can't negate A / B, because if A is INT_MIN and
480 B is 1, we may turn this into INT_MIN / -1 which is undefined
481 and actually traps on some architectures. But if overflow is
482 undefined, we can negate, because - (INT_MIN / 1) is an
483 overflow. */
485 {
488 /* If overflow is undefined then we have to be careful because
489 we ask whether it's ok to associate the negate with the
490 division which is not ok for example for
491 -((a - b) / c) where (-(a - b)) / c may invoke undefined
492 overflow because of negating INT_MIN. So do not use
493 negate_expr_p here but open-code the two important cases. */
498 }
504 /* Negate -((double)float) as (double)(-float). */
506 {
510 }
514 /* Negate -f(x) as f(-x). */
520 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
522 {
526 }
531 }
533 }
535 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
536 simplification is possible.
537 If negate_expr_p would return true for T, NULL_TREE will never be
538 returned. */
540 static tree
542 {
544 tree tem;
547 {
548 /* Convert - (~A) to A + 1. */
564 /* Two's complement FP formats, such as c4x, may overflow. */
574 {
583 }
587 {
592 {
596 }
599 }
620 {
621 /* -(A + B) -> (-B) - A. */
625 {
629 }
631 /* -(A + B) -> (-A) - B. */
633 {
637 }
638 }
642 /* - (A - B) -> B - A */
654 /* Fall through. */
658 {
667 }
673 /* In general we can't negate A / B, because if A is INT_MIN and
674 B is 1, we may turn this into INT_MIN / -1 which is undefined
675 and actually traps on some architectures. But if overflow is
676 undefined, we can negate, because - (INT_MIN / 1) is an
677 overflow. */
679 {
684 {
691 }
692 /* If overflow is undefined then we have to be careful because
693 we ask whether it's ok to associate the negate with the
694 division which is not ok for example for
695 -((a - b) / c) where (-(a - b)) / c may invoke undefined
696 overflow because of negating INT_MIN. So do not use
697 negate_expr_p here but open-code the two important cases. */
706 }
710 /* Convert -((double)float) into (double)(-float). */
712 {
716 }
720 /* Negate -f(x) as f(-x). */
723 {
729 }
733 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
735 {
738 {
745 }
746 }
751 }
754 }
756 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
757 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
758 return NULL_TREE. */
760 static tree
762 {
764 location_t loc;
777 }
778 \f
779 /* Split a tree IN into a constant, literal and variable parts that could be
780 combined with CODE to make IN. "constant" means an expression with
781 TREE_CONSTANT but that isn't an actual constant. CODE must be a
782 commutative arithmetic operation. Store the constant part into *CONP,
783 the literal in *LITP and return the variable part. If a part isn't
784 present, set it to null. If the tree does not decompose in this way,
785 return the entire tree as the variable part and the other parts as null.
787 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
788 case, we negate an operand that was subtracted. Except if it is a
789 literal for which we use *MINUS_LITP instead.
791 If NEGATE_P is true, we are negating all of IN, again except a literal
792 for which we use *MINUS_LITP instead.
794 If IN is itself a literal or constant, return it as appropriate.
796 Note that we do not guarantee that any of the three values will be the
797 same type as IN, but they will have the same signedness and mode. */
799 static tree
802 {
809 /* Strip any conversions that don't change the machine mode or signedness. */
818 /* We can associate addition and subtraction together (even
819 though the C standard doesn't say so) for integers because
820 the value is not affected. For reals, the value might be
821 affected, so we can't. */
824 {
830 /* First see if either of the operands is a literal, then a constant. */
843 /* If we haven't dealt with either operand, this is not a case we can
844 decompose. Otherwise, VAR is either of the ones remaining, if any. */
849 else
852 /* Now do any needed negations. */
859 }
862 {
863 /* -X - 1 is folded to ~X, undo that here. */
866 }
869 else
873 {
880 }
883 }
885 /* Re-associate trees split by the above function. T1 and T2 are
886 either expressions to associate or null. Return the new
887 expression, if any. LOC is the location of the new expression. If
888 we build an operation, do it in TYPE and with CODE. */
890 static tree
892 {
898 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
899 try to fold this since we will have infinite recursion. But do
900 deal with any NEGATE_EXPRs. */
903 {
905 {
918 }
920 {
923 }
927 }
931 }
932 \f
933 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
934 for use in int_const_binop, size_binop and size_diffop. */
936 static bool
938 {
945 {
954 }
959 }
962 /* Combine two integer constants ARG1 and ARG2 under operation CODE
963 to produce a new constant. Return NULL_TREE if we don't know how
964 to evaluate CODE at compile-time. */
966 static tree
969 {
970 wide_int res;
971 tree t;
980 {
996 {
1000 else
1002 }
1005 /* It's unclear from the C standard whether shifts can overflow.
1006 The following code ignores overflow; perhaps a C standard
1007 interpretation ruling is needed. */
1009 else
1016 {
1020 else
1022 }
1026 else
1105 }
1113 }
1115 tree
1117 {
1119 }
1121 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1122 constant. We assume ARG1 and ARG2 have the same data type, or at least
1123 are the same kind of constant and the same machine mode. Return zero if
1124 combining the constants is not allowed in the current operating mode. */
1126 static tree
1128 {
1129 /* Sanity check for the recursive cases. */
1140 {
1141 machine_mode mode;
1142 REAL_VALUE_TYPE d1;
1143 REAL_VALUE_TYPE d2;
1144 REAL_VALUE_TYPE value;
1145 REAL_VALUE_TYPE result;
1149 /* The following codes are handled by real_arithmetic. */
1151 {
1162 }
1170 /* Don't perform operation if we honor signaling NaNs and
1171 either operand is a NaN. */
1176 /* Don't perform operation if it would raise a division
1177 by zero exception. */
1183 /* If either operand is a NaN, just return it. Otherwise, set up
1184 for floating-point trap; we return an overflow. */
1193 /* Don't constant fold this floating point operation if
1194 the result has overflowed and flag_trapping_math. */
1202 /* Don't constant fold this floating point operation if the
1203 result may dependent upon the run-time rounding mode and
1204 flag_rounding_math is set, or if GCC's software emulation
1205 is unable to accurately represent the result. */
1215 }
1218 {
1219 FIXED_VALUE_TYPE f1;
1220 FIXED_VALUE_TYPE f2;
1221 FIXED_VALUE_TYPE result;
1226 /* The following codes are handled by fixed_arithmetic. */
1228 {
1238 {
1243 }
1248 }
1255 /* Propagate overflow flags. */
1259 }
1262 {
1271 {
1282 mpc_mul);
1296 mpc_div);
1297 /* Fallthru ... */
1303 {
1304 /* Keep this algorithm in sync with
1305 tree-complex.c:expand_complex_div_straight().
1307 Expand complex division to scalars, straightforward algorithm.
1308 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1309 t = br*br + bi*bi
1310 */
1311 tree magsquared
1315 tree t1
1319 tree t2
1326 }
1327 else
1328 {
1329 /* Keep this algorithm in sync with
1330 tree-complex.c:expand_complex_div_wide().
1332 Expand complex division to scalars, modified algorithm to minimize
1333 overflow with wide input ranges. */
1339 {
1340 /* In the TRUE branch, we compute
1341 ratio = br/bi;
1342 div = (br * ratio) + bi;
1343 tr = (ar * ratio) + ai;
1344 ti = (ai * ratio) - ar;
1345 tr = tr / div;
1346 ti = ti / div; */
1357 }
1358 else
1359 {
1360 /* In the FALSE branch, we compute
1361 ratio = d/c;
1362 divisor = (d * ratio) + c;
1363 tr = (b * ratio) + a;
1364 ti = b - (a * ratio);
1365 tr = tr / div;
1366 ti = ti / div; */
1378 }
1379 }
1384 }
1388 }
1392 {
1398 {
1404 /* It is possible that const_binop cannot handle the given
1405 code and return NULL_TREE */
1408 }
1411 }
1413 /* Shifts allow a scalar offset for a vector. */
1416 {
1422 {
1428 unsigned HOST_WIDE_INT innerc
1433 /* The direction of VEC_RSHIFT_EXPR is endian dependent.
1434 For reductions, if !BYTES_BIG_ENDIAN then compiler picks first
1435 vector element, but last element if BYTES_BIG_ENDIAN. */
1440 {
1443 else
1445 }
1446 }
1447 else
1449 {
1454 /* It is possible that const_binop cannot handle the given
1455 code and return NULL_TREE */
1458 }
1461 }
1463 }
1465 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1466 indicates which particular sizetype to create. */
1468 tree
1470 {
1472 }
1473 \f
1474 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1475 is a tree code. The type of the result is taken from the operands.
1476 Both must be equivalent integer types, ala int_binop_types_match_p.
1477 If the operands are constant, so is the result. */
1479 tree
1481 {
1490 /* Handle the special case of two integer constants faster. */
1492 {
1493 /* And some specific cases even faster than that. */
1495 {
1500 }
1502 {
1505 }
1507 {
1510 }
1512 /* Handle general case of two integer constants. For sizetype
1513 constant calculations we always want to know about overflow,
1514 even in the unsigned case. */
1516 }
1519 }
1521 /* Given two values, either both of sizetype or both of bitsizetype,
1522 compute the difference between the two values. Return the value
1523 in signed type corresponding to the type of the operands. */
1525 tree
1527 {
1529 tree ctype;
1534 /* If the type is already signed, just do the simple thing. */
1542 else
1545 /* If either operand is not a constant, do the conversions to the signed
1546 type and subtract. The hardware will do the right thing with any
1547 overflow in the subtraction. */
1553 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1554 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1555 overflow) and negate (which can't either). Special-case a result
1556 of zero while we're here. */
1562 else
1566 MINUS_EXPR,
1568 }
1569 \f
1570 /* A subroutine of fold_convert_const handling conversions of an
1571 INTEGER_CST to another integer type. */
1573 static tree
1575 {
1576 /* Given an integer constant, make new constant with new type,
1577 appropriately sign-extended or truncated. Use widest_int
1578 so that any extension is done according ARG1's type. */
1582 }
1584 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1585 to an integer type. */
1587 static tree
1589 {
1591 tree t;
1593 /* The following code implements the floating point to integer
1594 conversion rules required by the Java Language Specification,
1595 that IEEE NaNs are mapped to zero and values that overflow
1596 the target precision saturate, i.e. values greater than
1597 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1598 are mapped to INT_MIN. These semantics are allowed by the
1599 C and C++ standards that simply state that the behavior of
1600 FP-to-integer conversion is unspecified upon overflow. */
1602 wide_int val;
1603 REAL_VALUE_TYPE r;
1607 {
1614 }
1616 /* If R is NaN, return zero and show we have an overflow. */
1618 {
1621 }
1623 /* See if R is less than the lower bound or greater than the
1624 upper bound. */
1627 {
1631 {
1634 }
1635 }
1638 {
1641 {
1644 {
1647 }
1648 }
1649 }
1656 }
1658 /* A subroutine of fold_convert_const handling conversions of a
1659 FIXED_CST to an integer type. */
1661 static tree
1663 {
1664 tree t;
1668 /* Right shift FIXED_CST to temp by fbit. */
1672 {
1674 HOST_BITS_PER_DOUBLE_INT,
1677 /* Left shift temp to temp_trunc by fbit. */
1679 HOST_BITS_PER_DOUBLE_INT,
1681 }
1682 else
1683 {
1686 }
1688 /* If FIXED_CST is negative, we need to round the value toward 0.
1689 By checking if the fractional bits are not zero to add 1 to temp. */
1695 /* Given a fixed-point constant, make new constant with new type,
1696 appropriately sign-extended or truncated. */
1704 }
1706 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1707 to another floating point type. */
1709 static tree
1711 {
1712 REAL_VALUE_TYPE value;
1713 tree t;
1718 /* If converting an infinity or NAN to a representation that doesn't
1719 have one, set the overflow bit so that we can produce some kind of
1720 error message at the appropriate point if necessary. It's not the
1721 most user-friendly message, but it's better than nothing. */
1728 /* Regular overflow, conversion produced an infinity in a mode that
1729 can't represent them. */
1734 else
1737 }
1739 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1740 to a floating point type. */
1742 static tree
1744 {
1745 REAL_VALUE_TYPE value;
1746 tree t;
1753 }
1755 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1756 to another fixed-point type. */
1758 static tree
1760 {
1761 FIXED_VALUE_TYPE value;
1762 tree t;
1769 /* Propagate overflow flags. */
1773 }
1775 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
1776 to a fixed-point type. */
1778 static tree
1780 {
1781 FIXED_VALUE_TYPE value;
1782 tree t;
1784 double_int di;
1791 else
1799 /* Propagate overflow flags. */
1803 }
1805 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1806 to a fixed-point type. */
1808 static tree
1810 {
1811 FIXED_VALUE_TYPE value;
1812 tree t;
1820 /* Propagate overflow flags. */
1824 }
1826 /* Attempt to fold type conversion operation CODE of expression ARG1 to
1827 type TYPE. If no simplification can be done return NULL_TREE. */
1829 static tree
1831 {
1837 {
1844 }
1846 {
1853 }
1855 {
1862 }
1864 }
1866 /* Construct a vector of zero elements of vector type TYPE. */
1868 static tree
1870 {
1871 tree t;
1875 }
1877 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
1879 bool
1881 {
1896 {
1915 }
1916 }
1918 /* Convert expression ARG to type TYPE. Used by the middle-end for
1919 simple conversions in preference to calling the front-end's convert. */
1921 tree
1923 {
1925 tree tem;
1936 {
1939 /* Handle conversions between pointers to different address spaces. */
1944 /* fall through */
1949 {
1953 }
1967 {
1971 }
1973 {
1977 }
1979 {
1983 }
1986 {
2004 }
2009 {
2013 }
2016 {
2030 }
2034 {
2043 integer_zero_node));
2045 {
2049 {
2055 }
2063 }
2067 }
2085 }
2086 fold_convert_exit:
2089 }
2090 \f
2091 /* Return false if expr can be assumed not to be an lvalue, true
2092 otherwise. */
2094 static bool
2096 {
2097 /* We only need to wrap lvalue tree codes. */
2099 {
2130 /* Assume the worst for front-end tree codes. */
2134 }
2137 }
2139 /* Return an expr equal to X but certainly not valid as an lvalue. */
2141 tree
2143 {
2144 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2145 us. */
2152 }
2154 /* When pedantic, return an expr equal to X but certainly not valid as a
2155 pedantic lvalue. Otherwise, return X. */
2157 static tree
2159 {
2161 }
2162 \f
2163 /* Given a tree comparison code, return the code that is the logical inverse.
2164 It is generally not safe to do this for floating-point comparisons, except
2165 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2166 ERROR_MARK in this case. */
2168 enum tree_code
2170 {
2176 {
2207 }
2208 }
2210 /* Similar, but return the comparison that results if the operands are
2211 swapped. This is safe for floating-point. */
2213 enum tree_code
2215 {
2217 {
2243 }
2244 }
2247 /* Convert a comparison tree code from an enum tree_code representation
2248 into a compcode bit-based encoding. This function is the inverse of
2249 compcode_to_comparison. */
2251 static enum comparison_code
2253 {
2255 {
2286 }
2287 }
2289 /* Convert a compcode bit-based encoding of a comparison operator back
2290 to GCC's enum tree_code representation. This function is the
2291 inverse of comparison_to_compcode. */
2293 static enum tree_code
2295 {
2297 {
2328 }
2329 }
2331 /* Return a tree for the comparison which is the combination of
2332 doing the AND or OR (depending on CODE) of the two operations LCODE
2333 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2334 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2335 if this makes the transformation invalid. */
2337 tree
2342 {
2349 {
2360 }
2363 {
2364 /* Eliminate unordered comparisons, as well as LTGT and ORD
2365 which are not used unless the mode has NaNs. */
2371 }
2373 {
2374 /* Check that the original operation and the optimized ones will trap
2375 under the same condition. */
2386 /* In a short-circuited boolean expression the LHS might be
2387 such that the RHS, if evaluated, will never trap. For
2388 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2389 if neither x nor y is NaN. (This is a mixed blessing: for
2390 example, the expression above will never trap, hence
2391 optimizing it to x < y would be invalid). */
2396 /* If the comparison was short-circuited, and only the RHS
2397 trapped, we may now generate a spurious trap. */
2402 /* If we changed the conditions that cause a trap, we lose. */
2405 }
2411 else
2412 {
2417 }
2418 }
2419 \f
2420 /* Return nonzero if two operands (typically of the same tree node)
2421 are necessarily equal. If either argument has side-effects this
2422 function returns zero. FLAGS modifies behavior as follows:
2424 If OEP_ONLY_CONST is set, only return nonzero for constants.
2425 This function tests whether the operands are indistinguishable;
2426 it does not test whether they are equal using C's == operation.
2427 The distinction is important for IEEE floating point, because
2428 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2429 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2431 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2432 even though it may hold multiple values during a function.
2433 This is because a GCC tree node guarantees that nothing else is
2434 executed between the evaluation of its "operands" (which may often
2435 be evaluated in arbitrary order). Hence if the operands themselves
2436 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2437 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2438 unset means assuming isochronic (or instantaneous) tree equivalence.
2439 Unless comparing arbitrary expression trees, such as from different
2440 statements, this flag can usually be left unset.
2442 If OEP_PURE_SAME is set, then pure functions with identical arguments
2443 are considered the same. It is used when the caller has other ways
2444 to ensure that global memory is unchanged in between. */
2446 int
2448 {
2449 /* If either is ERROR_MARK, they aren't equal. */
2455 /* Similar, if either does not have a type (like a released SSA name),
2456 they aren't equal. */
2460 /* Check equality of integer constants before bailing out due to
2461 precision differences. */
2465 /* If both types don't have the same signedness, then we can't consider
2466 them equal. We must check this before the STRIP_NOPS calls
2467 because they may change the signedness of the arguments. As pointers
2468 strictly don't have a signedness, require either two pointers or
2469 two non-pointers as well. */
2474 /* We cannot consider pointers to different address space equal. */
2480 /* If both types don't have the same precision, then it is not safe
2481 to strip NOPs. */
2489 /* In case both args are comparisons but with different comparison
2490 code, try to swap the comparison operands of one arg to produce
2491 a match and compare that variant. */
2495 {
2503 }
2506 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2510 /* This is needed for conversions and for COMPONENT_REF.
2511 Might as well play it safe and always test this. */
2517 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2518 We don't care about side effects in that case because the SAVE_EXPR
2519 takes care of that for us. In all other cases, two expressions are
2520 equal if they have no side effects. If we have two identical
2521 expressions with side effects that should be treated the same due
2522 to the only side effects being identical SAVE_EXPR's, that will
2523 be detected in the recursive calls below.
2524 If we are taking an invariant address of two identical objects
2525 they are necessarily equal as well. */
2532 /* Next handle constant cases, those for which we can return 1 even
2533 if ONLY_CONST is set. */
2536 {
2551 {
2552 /* If we do not distinguish between signed and unsigned zero,
2553 consider them equal. */
2556 }
2560 {
2567 {
2571 }
2573 }
2577 flags)
2579 flags));
2593 }
2598 /* Define macros to test an operand from arg0 and arg1 for equality and a
2599 variant that allows null and views null as being different from any
2600 non-null value. In the latter case, if either is null, the both
2601 must be; otherwise, do the normal comparison. */
2602 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2603 TREE_OPERAND (arg1, N), flags)
2605 #define OP_SAME_WITH_NULL(N) \
2606 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2607 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2610 {
2612 /* Two conversions are equal only if signedness and modes match. */
2614 {
2615 CASE_CONVERT:
2623 }
2633 /* For commutative ops, allow the other order. */
2641 /* If either of the pointer (or reference) expressions we are
2642 dereferencing contain a side effect, these cannot be equal,
2643 but their addresses can be. */
2650 {
2661 /* Require equal extra operands and then fall through to MEM_REF
2662 handling of the two common operands. */
2667 /* Fallthru. */
2670 /* Require equal access sizes, and similar pointer types.
2671 We can have incomplete types for array references of
2672 variable-sized arrays from the Fortran frontend
2673 though. Also verify the types are compatible. */
2680 && alias_ptr_types_compatible_p
2687 /* Operands 2 and 3 may be null.
2688 Compare the array index by value if it is constant first as we
2689 may have different types but same value here. */
2700 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2701 may be NULL when we're called to compare MEM_EXPRs. */
2716 }
2720 {
2734 /* The multiplcation operands are commutative. */
2735 /* FALLTHRU */
2743 /* Otherwise take into account this is a commutative operation. */
2756 }
2760 {
2762 /* If the CALL_EXPRs call different functions, then they
2763 clearly can not be equal. */
2765 flags))
2768 {
2772 else
2776 }
2778 /* Now see if all the arguments are the same. */
2779 {
2790 /* If we get here and both argument lists are exhausted
2791 then the CALL_EXPRs are equal. */
2793 }
2796 }
2799 /* Consider __builtin_sqrt equal to sqrt. */
2807 }
2809 #undef OP_SAME
2810 #undef OP_SAME_WITH_NULL
2811 }
2812 \f
2813 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2814 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2816 When in doubt, return 0. */
2818 static int
2820 {
2832 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2833 and see if the inner values are the same. This removes any
2834 signedness comparison, which doesn't matter here. */
2841 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2842 actual comparison operand, ARG0.
2844 First throw away any conversions to wider types
2845 already present in the operands. */
2854 {
2857 /* Make sure shorter operand is extended the right way
2858 to match the longer operand. */
2864 }
2867 }
2868 \f
2869 /* See if ARG is an expression that is either a comparison or is performing
2870 arithmetic on comparisons. The comparisons must only be comparing
2871 two different values, which will be stored in *CVAL1 and *CVAL2; if
2872 they are nonzero it means that some operands have already been found.
2873 No variables may be used anywhere else in the expression except in the
2874 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2875 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2877 If this is true, return 1. Otherwise, return zero. */
2879 static int
2881 {
2885 /* We can handle some of the tcc_expression cases here. */
2895 {
2896 /* If we've already found a CVAL1 or CVAL2, this expression is
2897 two complex to handle. */
2903 }
2906 {
2929 /* First see if we can handle the first operand, then the second. For
2930 the second operand, we know *CVAL1 can't be zero. It must be that
2931 one side of the comparison is each of the values; test for the
2932 case where this isn't true by failing if the two operands
2933 are the same. */
2942 ;
2946 ;
2947 else
2951 ;
2955 ;
2956 else
2963 }
2964 }
2965 \f
2966 /* ARG is a tree that is known to contain just arithmetic operations and
2967 comparisons. Evaluate the operations in the tree substituting NEW0 for
2968 any occurrence of OLD0 as an operand of a comparison and likewise for
2969 NEW1 and OLD1. */
2971 static tree
2974 {
2979 /* We can handle some of the tcc_expression cases here. */
2987 {
3002 {
3021 }
3022 /* Fall through - ??? */
3025 {
3029 /* We need to check both for exact equality and tree equality. The
3030 former will be true if the operand has a side-effect. In that
3031 case, we know the operand occurred exactly once. */
3044 }
3048 }
3049 }
3050 \f
3051 /* Return a tree for the case when the result of an expression is RESULT
3052 converted to TYPE and OMITTED was previously an operand of the expression
3053 but is now not needed (e.g., we folded OMITTED * 0).
3055 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3056 the conversion of RESULT to TYPE. */
3058 tree
3060 {
3063 /* If the resulting operand is an empty statement, just return the omitted
3064 statement casted to void. */
3074 }
3076 /* Return a tree for the case when the result of an expression is RESULT
3077 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3078 of the expression but are now not needed.
3080 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3081 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3082 evaluated before OMITTED2. Otherwise, if neither has side effects,
3083 just do the conversion of RESULT to TYPE. */
3085 tree
3088 {
3097 }
3099 \f
3100 /* Return a simplified tree node for the truth-negation of ARG. This
3101 never alters ARG itself. We assume that ARG is an operation that
3102 returns a truth value (0 or 1).
3104 FIXME: one would think we would fold the result, but it causes
3105 problems with the dominator optimizer. */
3107 static tree
3109 {
3114 /* If this is a comparison, we can simply invert it, except for
3115 floating-point non-equality comparisons, in which case we just
3116 enclose a TRUTH_NOT_EXPR around what we have. */
3119 {
3122 && flag_trapping_math
3133 }
3136 {
3155 /* Here we can invert either operand. We invert the first operand
3156 unless the second operand is a TRUTH_NOT_EXPR in which case our
3157 result is the XOR of the first operand with the inside of the
3158 negation of the second operand. */
3163 else
3186 {
3193 /* A COND_EXPR may have a throw as one operand, which
3194 then has void type. Just leave void operands
3195 as they are. */
3201 }
3213 CASE_CONVERT:
3217 /* ... fall through ... */
3239 }
3240 }
3242 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3243 assume that ARG is an operation that returns a truth value (0 or 1
3244 for scalars, 0 or -1 for vectors). Return the folded expression if
3245 folding is successful. Otherwise, return NULL_TREE. */
3247 static tree
3249 {
3252 ? BIT_NOT_EXPR
3255 }
3257 /* Return a simplified tree node for the truth-negation of ARG. This
3258 never alters ARG itself. We assume that ARG is an operation that
3259 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3261 tree
3263 {
3269 ? BIT_NOT_EXPR
3272 }
3274 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3275 operands are another bit-wise operation with a common input. If so,
3276 distribute the bit operations to save an operation and possibly two if
3277 constants are involved. For example, convert
3278 (A | B) & (A | C) into A | (B & C)
3279 Further simplification will occur if B and C are constants.
3281 If this optimization cannot be done, 0 will be returned. */
3283 static tree
3286 {
3287 tree common;
3297 {
3301 }
3303 {
3307 }
3309 {
3313 }
3315 {
3319 }
3320 else
3328 }
3330 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3331 with code CODE. This optimization is unsafe. */
3332 static tree
3335 {
3339 /* (A / C) +- (B / C) -> (A +- B) / C. */
3349 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3354 {
3366 }
3369 }
3370 \f
3371 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3372 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3374 static tree
3377 {
3381 {
3388 }
3402 }
3404 /* Optimize a bit-field compare.
3406 There are two cases: First is a compare against a constant and the
3407 second is a comparison of two items where the fields are at the same
3408 bit position relative to the start of a chunk (byte, halfword, word)
3409 large enough to contain it. In these cases we can avoid the shift
3410 implicit in bitfield extractions.
3412 For constants, we emit a compare of the shifted constant with the
3413 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3414 compared. For two fields at the same position, we do the ANDs with the
3415 similar mask and compare the result of the ANDs.
3417 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3418 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3419 are the left and right operands of the comparison, respectively.
3421 If the optimization described above can be done, we return the resulting
3422 tree. Otherwise we return zero. */
3424 static tree
3427 {
3430 tree unsigned_type;
3436 tree mask;
3437 tree offset;
3439 /* Get all the information about the extractions being done. If the bit size
3440 if the same as the size of the underlying object, we aren't doing an
3441 extraction at all and so can do nothing. We also don't want to
3442 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3443 then will no longer be able to replace it. */
3451 {
3452 /* If this is not a constant, we can only do something if bit positions,
3453 sizes, and signedness are the same. */
3461 }
3463 /* See if we can find a mode to refer to this field. We should be able to,
3464 but fail if we can't. */
3473 /* Set signed and unsigned types of the precision of this mode for the
3474 shifts below. */
3477 /* Compute the bit position and size for the new reference and our offset
3478 within it. If the new reference is the same size as the original, we
3479 won't optimize anything, so return zero. */
3489 /* Make the mask to be used against the extracted field. */
3496 /* If not comparing with constant, just rework the comparison
3497 and return. */
3501 unsigned_type,
3504 mask),
3507 unsigned_type,
3510 mask));
3512 /* Otherwise, we are handling the constant case. See if the constant is too
3513 big for the field. Warn and return a tree of for 0 (false) if so. We do
3514 this not only for its own sake, but to avoid having to test for this
3515 error case below. If we didn't, we might generate wrong code.
3517 For unsigned fields, the constant shifted right by the field length should
3518 be all zero. For signed fields, the high-order bits should agree with
3519 the sign bit. */
3522 {
3524 {
3528 }
3529 }
3530 else
3531 {
3534 {
3538 }
3539 }
3541 /* Single-bit compares should always be against zero. */
3543 {
3546 }
3548 /* Make a new bitfield reference, shift the constant over the
3549 appropriate number of bits and mask it with the computed mask
3550 (in case this was a signed field). If we changed it, make a new one. */
3557 mask);
3562 }
3563 \f
3564 /* Subroutine for fold_truth_andor_1: decode a field reference.
3566 If EXP is a comparison reference, we return the innermost reference.
3568 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3569 set to the starting bit number.
3571 If the innermost field can be completely contained in a mode-sized
3572 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3574 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3575 otherwise it is not changed.
3577 *PUNSIGNEDP is set to the signedness of the field.
3579 *PMASK is set to the mask used. This is either contained in a
3580 BIT_AND_EXPR or derived from the width of the field.
3582 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3584 Return 0 if this is not a component reference or is one that we can't
3585 do anything with. */
3587 static tree
3592 {
3596 tree unsigned_type;
3599 /* All the optimizations using this function assume integer fields.
3600 There are problems with FP fields since the type_for_size call
3601 below can fail for, e.g., XFmode. */
3605 /* We are interested in the bare arrangement of bits, so strip everything
3606 that doesn't affect the machine mode. However, record the type of the
3607 outermost expression if it may matter below. */
3614 {
3620 }
3629 /* If the number of bits in the reference is the same as the bitsize of
3630 the outer type, then the outer type gives the signedness. Otherwise
3631 (in case of a small bitfield) the signedness is unchanged. */
3635 /* Compute the mask to access the bitfield. */
3644 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3652 }
3654 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3655 bit positions and MASK is SIGNED. */
3657 static int
3659 {
3663 /* If this function returns true when the type of the mask is
3664 UNSIGNED, then there will be errors. In particular see
3665 gcc.c-torture/execute/990326-1.c. There does not appear to be
3666 any documentation paper trail as to why this is so. But the pre
3667 wide-int worked with that restriction and it has been preserved
3668 here. */
3673 }
3675 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3676 represents the sign bit of EXP's type. If EXP represents a sign
3677 or zero extension, also test VAL against the unextended type.
3678 The return value is the (sub)expression whose sign bit is VAL,
3679 or NULL_TREE otherwise. */
3681 static tree
3683 {
3685 tree t;
3687 /* Tree EXP must have an integral type. */
3692 /* Tree VAL must be an integer constant. */
3701 /* Handle extension from a narrower type. */
3707 }
3709 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3710 to be evaluated unconditionally. */
3712 static int
3714 {
3715 /* Strip any conversions that don't change the machine mode. */
3724 /* Don't regard global variables as simple. They may be
3725 allocated in ways unknown to the compiler (shared memory,
3726 #pragma weak, etc). */
3729 /* Weakrefs are not safe to be read, since they can be NULL.
3730 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3731 have DECL_WEAK flag set. */
3733 /* Loading a static variable is unduly expensive, but global
3734 registers aren't expensive. */
3736 }
3738 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3739 to be evaluated unconditionally.
3740 I addition to simple_operand_p, we assume that comparisons, conversions,
3741 and logic-not operations are simple, if their operands are simple, too. */
3743 static bool
3745 {
3765 }
3767 \f
3768 /* The following functions are subroutines to fold_range_test and allow it to
3769 try to change a logical combination of comparisons into a range test.
3771 For example, both
3772 X == 2 || X == 3 || X == 4 || X == 5
3773 and
3774 X >= 2 && X <= 5
3775 are converted to
3776 (unsigned) (X - 2) <= 3
3778 We describe each set of comparisons as being either inside or outside
3779 a range, using a variable named like IN_P, and then describe the
3780 range with a lower and upper bound. If one of the bounds is omitted,
3781 it represents either the highest or lowest value of the type.
3783 In the comments below, we represent a range by two numbers in brackets
3784 preceded by a "+" to designate being inside that range, or a "-" to
3785 designate being outside that range, so the condition can be inverted by
3786 flipping the prefix. An omitted bound is represented by a "-". For
3787 example, "- [-, 10]" means being outside the range starting at the lowest
3788 possible value and ending at 10, in other words, being greater than 10.
3789 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3790 always false.
3792 We set up things so that the missing bounds are handled in a consistent
3793 manner so neither a missing bound nor "true" and "false" need to be
3794 handled using a special case. */
3796 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3797 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3798 and UPPER1_P are nonzero if the respective argument is an upper bound
3799 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3800 must be specified for a comparison. ARG1 will be converted to ARG0's
3801 type if both are specified. */
3803 static tree
3806 {
3807 tree tem;
3811 /* If neither arg represents infinity, do the normal operation.
3812 Else, if not a comparison, return infinity. Else handle the special
3813 comparison rules. Note that most of the cases below won't occur, but
3814 are handled for consistency. */
3817 {
3822 }
3827 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3828 for neither. In real maths, we cannot assume open ended ranges are
3829 the same. But, this is computer arithmetic, where numbers are finite.
3830 We can therefore make the transformation of any unbounded range with
3831 the value Z, Z being greater than any representable number. This permits
3832 us to treat unbounded ranges as equal. */
3836 {
3857 }
3860 }
3861 \f
3862 /* Helper routine for make_range. Perform one step for it, return
3863 new expression if the loop should continue or NULL_TREE if it should
3864 stop. */
3866 tree
3870 {
3876 {
3878 /* We can only do something if the range is testing for zero. */
3887 /* We can only do something if the range is testing for zero
3888 and if the second operand is an integer constant. Note that
3889 saying something is "in" the range we make is done by
3890 complementing IN_P since it will set in the initial case of
3891 being not equal to zero; "out" is leaving it alone. */
3898 {
3919 }
3921 /* If this is an unsigned comparison, we also know that EXP is
3922 greater than or equal to zero. We base the range tests we make
3923 on that fact, so we record it here so we can parse existing
3924 range tests. We test arg0_type since often the return type
3925 of, e.g. EQ_EXPR, is boolean. */
3927 {
3931 NULL_TREE))
3936 /* If the high bound is missing, but we have a nonzero low
3937 bound, reverse the range so it goes from zero to the low bound
3938 minus 1. */
3940 {
3945 }
3946 }
3954 /* If flag_wrapv and ARG0_TYPE is signed, make sure
3955 low and high are non-NULL, then normalize will DTRT. */
3958 {
3963 }
3965 /* (-x) IN [a,b] -> x in [-b, -a] */
3977 /* ~ X -> -X - 1 */
3986 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
3987 move a constant to the other side. */
3992 /* If EXP is signed, any overflow in the computation is undefined,
3993 so we don't worry about it so long as our computations on
3994 the bounds don't overflow. For unsigned, overflow is defined
3995 and this is exactly the right thing. */
4007 normalize:
4008 /* Check for an unsigned range which has wrapped around the maximum
4009 value thus making n_high < n_low, and normalize it. */
4011 {
4017 /* If the range is of the form +/- [ x+1, x ], we won't
4018 be able to normalize it. But then, it represents the
4019 whole range or the empty set, so make it
4020 +/- [ -, - ]. */
4024 else
4026 }
4027 else
4035 CASE_CONVERT:
4053 /* If we're converting arg0 from an unsigned type, to exp,
4054 a signed type, we will be doing the comparison as unsigned.
4055 The tests above have already verified that LOW and HIGH
4056 are both positive.
4058 So we have to ensure that we will handle large unsigned
4059 values the same way that the current signed bounds treat
4060 negative values. */
4063 {
4064 tree high_positive;
4065 tree equiv_type;
4066 /* For fixed-point modes, we need to pass the saturating flag
4067 as the 2nd parameter. */
4069 equiv_type
4072 else
4073 equiv_type
4076 /* A range without an upper bound is, naturally, unbounded.
4077 Since convert would have cropped a very large value, use
4078 the max value for the destination type. */
4079 high_positive
4086 high_positive),
4089 /* If the low bound is specified, "and" the range with the
4090 range for which the original unsigned value will be
4091 positive. */
4093 {
4096 integer_zero_node),
4097 high_positive))
4101 }
4102 else
4103 {
4104 /* Otherwise, "or" the range with the range of the input
4105 that will be interpreted as negative. */
4108 integer_zero_node),
4109 high_positive))
4113 }
4114 }
4123 }
4124 }
4126 /* Given EXP, a logical expression, set the range it is testing into
4127 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4128 actually being tested. *PLOW and *PHIGH will be made of the same
4129 type as the returned expression. If EXP is not a comparison, we
4130 will most likely not be returning a useful value and range. Set
4131 *STRICT_OVERFLOW_P to true if the return value is only valid
4132 because signed overflow is undefined; otherwise, do not change
4133 *STRICT_OVERFLOW_P. */
4135 tree
4138 {
4146 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4147 and see if we can refine the range. Some of the cases below may not
4148 happen, but it doesn't seem worth worrying about this. We "continue"
4149 the outer loop when we've changed something; otherwise we "break"
4150 the switch, which will "break" the while. */
4156 {
4162 {
4170 }
4179 }
4181 /* If EXP is a constant, we can evaluate whether this is true or false. */
4183 {
4190 }
4194 }
4195 \f
4196 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4197 type, TYPE, return an expression to test if EXP is in (or out of, depending
4198 on IN_P) the range. Return 0 if the test couldn't be created. */
4200 tree
4203 {
4206 #ifdef HAVE_canonicalize_funcptr_for_compare
4207 /* Disable this optimization for function pointer expressions
4208 on targets that require function pointer canonicalization. */
4213 #endif
4216 {
4222 }
4240 {
4242 {
4246 }
4248 }
4250 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4252 {
4256 {
4258 {
4261 etype
4263 else
4266 }
4269 }
4270 }
4272 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4273 This requires wrap-around arithmetics for the type of the expression.
4274 First make sure that arithmetics in this type is valid, then make sure
4275 that it wraps around. */
4281 {
4284 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4285 for the type in question, as we rely on this here. */
4295 else
4297 }
4307 {
4309 {
4314 }
4316 }
4324 }
4325 \f
4326 /* Return the predecessor of VAL in its type, handling the infinite case. */
4328 static tree
4330 {
4336 else
4339 }
4341 /* Return the successor of VAL in its type, handling the infinite case. */
4343 static tree
4345 {
4351 else
4354 }
4356 /* Given two ranges, see if we can merge them into one. Return 1 if we
4357 can, 0 if we can't. Set the output range into the specified parameters. */
4359 bool
4362 {
4366 tree tem;
4376 /* Make range 0 be the range that starts first, or ends last if they
4377 start at the same value. Swap them if it isn't. */
4380 || (lowequal
4383 {
4387 }
4389 /* Now flag two cases, whether the ranges are disjoint or whether the
4390 second range is totally subsumed in the first. Note that the tests
4391 below are simplified by the ones above. */
4397 /* We now have four cases, depending on whether we are including or
4398 excluding the two ranges. */
4400 {
4401 /* If they don't overlap, the result is false. If the second range
4402 is a subset it is the result. Otherwise, the range is from the start
4403 of the second to the end of the first. */
4408 else
4410 }
4413 {
4414 /* If they don't overlap, the result is the first range. If they are
4415 equal, the result is false. If the second range is a subset of the
4416 first, and the ranges begin at the same place, we go from just after
4417 the end of the second range to the end of the first. If the second
4418 range is not a subset of the first, or if it is a subset and both
4419 ranges end at the same place, the range starts at the start of the
4420 first range and ends just before the second range.
4421 Otherwise, we can't describe this as a single range. */
4427 {
4432 {
4433 /* We are in the weird situation where high0 > high1 but
4434 high1 has no successor. Punt. */
4436 }
4437 }
4439 {
4444 {
4445 /* low0 < low1 but low1 has no predecessor. Punt. */
4447 }
4448 }
4449 else
4451 }
4454 {
4455 /* If they don't overlap, the result is the second range. If the second
4456 is a subset of the first, the result is false. Otherwise,
4457 the range starts just after the first range and ends at the
4458 end of the second. */
4463 else
4464 {
4469 {
4470 /* high1 > high0 but high0 has no successor. Punt. */
4472 }
4473 }
4474 }
4476 else
4477 {
4478 /* The case where we are excluding both ranges. Here the complex case
4479 is if they don't overlap. In that case, the only time we have a
4480 range is if they are adjacent. If the second is a subset of the
4481 first, the result is the first. Otherwise, the range to exclude
4482 starts at the beginning of the first range and ends at the end of the
4483 second. */
4485 {
4490 else
4491 {
4492 /* Canonicalize - [min, x] into - [-, x]. */
4495 {
4500 /* FALLTHROUGH */
4513 }
4515 /* Canonicalize - [x, max] into - [x, -]. */
4518 {
4523 /* FALLTHROUGH */
4539 }
4541 /* The ranges might be also adjacent between the maximum and
4542 minimum values of the given type. For
4543 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4544 return + [x + 1, y - 1]. */
4546 {
4553 }
4554 else
4556 }
4557 }
4560 else
4562 }
4566 }
4567 \f
4569 /* Subroutine of fold, looking inside expressions of the form
4570 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4571 of the COND_EXPR. This function is being used also to optimize
4572 A op B ? C : A, by reversing the comparison first.
4574 Return a folded expression whose code is not a COND_EXPR
4575 anymore, or NULL_TREE if no folding opportunity is found. */
4577 static tree
4580 {
4585 tree tem;
4590 /* If we have A op 0 ? A : -A, consider applying the following
4591 transformations:
4593 A == 0? A : -A same as -A
4594 A != 0? A : -A same as A
4595 A >= 0? A : -A same as abs (A)
4596 A > 0? A : -A same as abs (A)
4597 A <= 0? A : -A same as -abs (A)
4598 A < 0? A : -A same as -abs (A)
4600 None of these transformations work for modes with signed
4601 zeros. If A is +/-0, the first two transformations will
4602 change the sign of the result (from +0 to -0, or vice
4603 versa). The last four will fix the sign of the result,
4604 even though the original expressions could be positive or
4605 negative, depending on the sign of A.
4607 Note that all these transformations are correct if A is
4608 NaN, since the two alternatives (A and -A) are also NaNs. */
4615 /* In the case that A is of the form X-Y, '-A' (arg2) may
4616 have already been folded to Y-X, check for that. */
4624 {
4638 /* Fall through. */
4660 }
4662 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4663 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4664 both transformations are correct when A is NaN: A != 0
4665 is then true, and A == 0 is false. */
4669 {
4674 }
4676 /* Try some transformations of A op B ? A : B.
4678 A == B? A : B same as B
4679 A != B? A : B same as A
4680 A >= B? A : B same as max (A, B)
4681 A > B? A : B same as max (B, A)
4682 A <= B? A : B same as min (A, B)
4683 A < B? A : B same as min (B, A)
4685 As above, these transformations don't work in the presence
4686 of signed zeros. For example, if A and B are zeros of
4687 opposite sign, the first two transformations will change
4688 the sign of the result. In the last four, the original
4689 expressions give different results for (A=+0, B=-0) and
4690 (A=-0, B=+0), but the transformed expressions do not.
4692 The first two transformations are correct if either A or B
4693 is a NaN. In the first transformation, the condition will
4694 be false, and B will indeed be chosen. In the case of the
4695 second transformation, the condition A != B will be true,
4696 and A will be chosen.
4698 The conversions to max() and min() are not correct if B is
4699 a number and A is not. The conditions in the original
4700 expressions will be false, so all four give B. The min()
4701 and max() versions would give a NaN instead. */
4704 /* Avoid these transformations if the COND_EXPR may be used
4705 as an lvalue in the C++ front-end. PR c++/19199. */
4706 && (in_gimple_form
4712 {
4717 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4719 {
4723 }
4726 {
4735 /* In C++ a ?: expression can be an lvalue, so put the
4736 operand which will be used if they are equal first
4737 so that we can convert this back to the
4738 corresponding COND_EXPR. */
4740 {
4749 }
4756 {
4765 }
4780 }
4781 }
4783 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4784 we might still be able to simplify this. For example,
4785 if C1 is one less or one more than C2, this might have started
4786 out as a MIN or MAX and been transformed by this function.
4787 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4793 {
4797 /* We can replace A with C1 in this case. */
4802 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
4803 MIN_EXPR, to preserve the signedness of the comparison. */
4805 OEP_ONLY_CONST)
4809 OEP_ONLY_CONST))
4810 {
4813 arg2));
4816 }
4820 /* If C1 is C2 - 1, this is min(A, C2), with the same care
4821 as above. */
4823 OEP_ONLY_CONST)
4827 OEP_ONLY_CONST))
4828 {
4831 arg2));
4834 }
4838 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
4839 MAX_EXPR, to preserve the signedness of the comparison. */
4841 OEP_ONLY_CONST)
4845 OEP_ONLY_CONST))
4846 {
4849 arg2));
4851 }
4855 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
4857 OEP_ONLY_CONST)
4861 OEP_ONLY_CONST))
4862 {
4865 arg2));
4867 }
4873 }
4876 }
4879 \f
4880 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4881 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
4882 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
4883 false) >= 2)
4884 #endif
4886 /* EXP is some logical combination of boolean tests. See if we can
4887 merge it into some range test. Return the new tree if so. */
4889 static tree
4892 {
4908 /* If this is an OR operation, invert both sides; we will invert
4909 again at the end. */
4913 /* If both expressions are the same, if we can merge the ranges, and we
4914 can build the range test, return it or it inverted. If one of the
4915 ranges is always true or always false, consider it to be the same
4916 expression as the other. */
4924 {
4928 }
4930 /* On machines where the branch cost is expensive, if this is a
4931 short-circuited branch and the underlying object on both sides
4932 is the same, make a non-short-circuit operation. */
4938 {
4939 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4940 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4941 which cases we can't do this. */
4949 {
4958 {
4961 WARN_STRICT_OVERFLOW_COMPARISON);
4965 }
4966 }
4967 }
4970 }
4971 \f
4972 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
4973 bit value. Arrange things so the extra bits will be set to zero if and
4974 only if C is signed-extended to its full width. If MASK is nonzero,
4975 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4977 static tree
4979 {
4982 tree temp;
4987 /* We work by getting just the sign bit into the low-order bit, then
4988 into the high-order bit, then sign-extend. We then XOR that value
4989 with C. */
4992 /* We must use a signed type in order to get an arithmetic right shift.
4993 However, we must also avoid introducing accidental overflows, so that
4994 a subsequent call to integer_zerop will work. Hence we must
4995 do the type conversion here. At this point, the constant is either
4996 zero or one, and the conversion to a signed type can never overflow.
4997 We could get an overflow if this conversion is done anywhere else. */
5006 /* If necessary, convert the type back to match the type of C. */
5011 }
5012 \f
5013 /* For an expression that has the form
5014 (A && B) || ~B
5015 or
5016 (A || B) && ~B,
5017 we can drop one of the inner expressions and simplify to
5018 A || ~B
5019 or
5020 A && ~B
5021 LOC is the location of the resulting expression. OP is the inner
5022 logical operation; the left-hand side in the examples above, while CMPOP
5023 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5024 removing a condition that guards another, as in
5025 (A != NULL && A->...) || A == NULL
5026 which we must not transform. If RHS_ONLY is true, only eliminate the
5027 right-most operand of the inner logical operation. */
5029 static tree
5032 {
5050 {
5053 {
5056 }
5057 }
5059 {
5062 {
5065 }
5066 }
5081 }
5083 /* Find ways of folding logical expressions of LHS and RHS:
5084 Try to merge two comparisons to the same innermost item.
5085 Look for range tests like "ch >= '0' && ch <= '9'".
5086 Look for combinations of simple terms on machines with expensive branches
5087 and evaluate the RHS unconditionally.
5089 For example, if we have p->a == 2 && p->b == 4 and we can make an
5090 object large enough to span both A and B, we can do this with a comparison
5091 against the object ANDed with the a mask.
5093 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5094 operations to do this with one comparison.
5096 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5097 function and the one above.
5099 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5100 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5102 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5103 two operands.
5105 We return the simplified tree or 0 if no optimization is possible. */
5107 static tree
5110 {
5111 /* If this is the "or" of two comparisons, we can do something if
5112 the comparisons are NE_EXPR. If this is the "and", we can do something
5113 if the comparisons are EQ_EXPR. I.e.,
5114 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5116 WANTED_CODE is this operation code. For single bit fields, we can
5117 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5118 comparison for one-bit fields. */
5138 /* Start by getting the comparison codes. Fail if anything is volatile.
5139 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5140 it were surrounded with a NE_EXPR. */
5149 {
5153 }
5156 {
5160 }
5171 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5174 {
5177 {
5182 }
5185 {
5191 }
5192 }
5197 /* If the RHS can be evaluated unconditionally and its operands are
5198 simple, it wins to evaluate the RHS unconditionally on machines
5199 with expensive branches. In this case, this isn't a comparison
5200 that can be merged. */
5207 {
5208 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5219 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5229 }
5231 /* See if the comparisons can be merged. Then get all the parameters for
5232 each side. */
5256 /* It must be true that the inner operation on the lhs of each
5257 comparison must be the same if we are to be able to do anything.
5258 Then see if we have constants. If not, the same must be true for
5259 the rhs's. */
5270 else
5273 /* If either comparison code is not correct for our logical operation,
5274 fail. However, we can convert a one-bit comparison against zero into
5275 the opposite comparison against that bit being set in the field. */
5279 {
5281 {
5282 /* Make the left operand unsigned, since we are only interested
5283 in the value of one bit. Otherwise we are doing the wrong
5284 thing below. */
5287 }
5288 else
5290 }
5292 /* This is analogous to the code for l_const above. */
5294 {
5296 {
5299 }
5300 else
5302 }
5304 /* See if we can find a mode that contains both fields being compared on
5305 the left. If we can't, fail. Otherwise, update all constants and masks
5306 to be relative to a field of that size. */
5311 volatilep);
5321 {
5324 }
5332 {
5339 {
5343 }
5344 }
5346 {
5353 {
5357 }
5358 }
5360 /* If the right sides are not constant, do the same for it. Also,
5361 disallow this optimization if a size or signedness mismatch occurs
5362 between the left and right sides. */
5364 {
5367 /* Make sure the two fields on the right
5368 correspond to the left without being swapped. */
5376 volatilep);
5386 {
5389 }
5398 /* Make a mask that corresponds to both fields being compared.
5399 Do this for both items being compared. If the operands are the
5400 same size and the bits being compared are in the same position
5401 then we can do this by masking both and comparing the masked
5402 results. */
5406 {
5418 }
5420 /* There is still another way we can do something: If both pairs of
5421 fields being compared are adjacent, we may be able to make a wider
5422 field containing them both.
5424 Note that we still must mask the lhs/rhs expressions. Furthermore,
5425 the mask must be shifted to account for the shift done by
5426 make_bit_field_ref. */
5431 {
5432 tree type;
5446 /* Convert to the smaller type before masking out unwanted bits. */
5449 {
5451 {
5455 }
5457 {
5461 }
5462 }
5471 }
5474 }
5476 /* Handle the case of comparisons with constants. If there is something in
5477 common between the masks, those bits of the constants must be the same.
5478 If not, the condition is always false. Test for this to avoid generating
5479 incorrect code below. */
5484 {
5486 {
5489 }
5490 else
5491 {
5494 }
5495 }
5497 /* Construct the expression we will return. First get the component
5498 reference we will make. Unless the mask is all ones the width of
5499 that field, perform the mask operation. Then compare with the
5500 merged constant. */
5510 }
5511 \f
5512 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5513 constant. */
5515 static tree
5518 {
5521 tree comp_const;
5522 tree minmax_const;
5524 tree inner;
5535 /* If something does not permit us to optimize, return the original tree. */
5543 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5544 and GT_EXPR, doing the rest with recursive calls using logical
5545 simplifications. */
5547 {
5549 {
5550 tree tem
5557 }
5560 return
5562 optimize_minmax_comparison
5564 optimize_minmax_comparison
5569 /* MAX (X, 0) == 0 -> X <= 0 */
5573 /* MAX (X, 0) == 5 -> X == 5 */
5577 /* MAX (X, 0) == -1 -> false */
5581 /* MIN (X, 0) == 0 -> X >= 0 */
5585 /* MIN (X, 0) == 5 -> false */
5588 else
5589 /* MIN (X, 0) == -1 -> X == -1 */
5594 /* MAX (X, 0) > 0 -> X > 0
5595 MAX (X, 0) > 5 -> X > 5 */
5599 /* MAX (X, 0) > -1 -> true */
5603 /* MIN (X, 0) > 0 -> false
5604 MIN (X, 0) > 5 -> false */
5607 else
5608 /* MIN (X, 0) > -1 -> X > -1 */
5613 }
5614 }
5615 \f
5616 /* T is an integer expression that is being multiplied, divided, or taken a
5617 modulus (CODE says which and what kind of divide or modulus) by a
5618 constant C. See if we can eliminate that operation by folding it with
5619 other operations already in T. WIDE_TYPE, if non-null, is a type that
5620 should be used for the computation if wider than our type.
5622 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5623 (X * 2) + (Y * 4). We must, however, be assured that either the original
5624 expression would not overflow or that overflow is undefined for the type
5625 in the language in question.
5627 If we return a non-null expression, it is an equivalent form of the
5628 original computation, but need not be in the original type.
5630 We set *STRICT_OVERFLOW_P to true if the return values depends on
5631 signed overflow being undefined. Otherwise we do not change
5632 *STRICT_OVERFLOW_P. */
5634 static tree
5637 {
5638 /* To avoid exponential search depth, refuse to allow recursion past
5639 three levels. Beyond that (1) it's highly unlikely that we'll find
5640 something interesting and (2) we've probably processed it before
5641 when we built the inner expression. */
5644 tree ret;
5649 depth++;
5651 depth--;
5654 }
5656 static tree
5659 {
5670 /* Don't deal with constants of zero here; they confuse the code below. */
5680 /* Note that we need not handle conditional operations here since fold
5681 already handles those cases. So just do arithmetic here. */
5683 {
5685 /* For a constant, we can always simplify if we are a multiply
5686 or (for divide and modulus) if it is a multiple of our constant. */
5694 /* If op0 is an expression ... */
5700 /* ... and has wrapping overflow, and its type is smaller
5701 than ctype, then we cannot pass through as widening. */
5705 /* ... or this is a truncation (t is narrower than op0),
5706 then we cannot pass through this narrowing. */
5709 /* ... or signedness changes for division or modulus,
5710 then we cannot pass through this conversion. */
5714 /* ... or has undefined overflow while the converted to
5715 type has not, we cannot do the operation in the inner type
5716 as that would introduce undefined overflow. */
5721 /* Pass the constant down and see if we can make a simplification. If
5722 we can, replace this expression with the inner simplification for
5723 possible later conversion to our or some other type. */
5728 code == MULT_EXPR
5730 strict_overflow_p))))
5735 /* If widening the type changes it from signed to unsigned, then we
5736 must avoid building ABS_EXPR itself as unsigned. */
5738 {
5742 {
5745 }
5747 }
5748 /* If the constant is negative, we cannot simplify this. */
5751 /* FALLTHROUGH */
5753 /* For division and modulus, type can't be unsigned, as e.g.
5754 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
5755 For signed types, even with wrapping overflow, this is fine. */
5764 /* If widening the type changes the signedness, then we can't perform
5765 this optimization as that changes the result. */
5769 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5775 {
5782 }
5786 /* If the second operand is constant, this is a multiplication
5787 or floor division, by a power of two, so we can treat it that
5788 way unless the multiplier or divisor overflows. Signed
5789 left-shift overflow is implementation-defined rather than
5790 undefined in C90, so do not convert signed left shift into
5791 multiplication. */
5794 /* const_binop may not detect overflow correctly,
5795 so check for it explicitly here. */
5799 size_one_node,
5800 op1)))
5804 ctype,
5806 t1),
5811 /* See if we can eliminate the operation on both sides. If we can, we
5812 can return a new PLUS or MINUS. If we can't, the only remaining
5813 cases where we can do anything are if the second operand is a
5814 constant. */
5820 /* If not multiplication, we can only do this if both operands
5821 are divisible by c. */
5824 {
5829 }
5831 /* If this was a subtraction, negate OP1 and set it to be an addition.
5832 This simplifies the logic below. */
5834 {
5836 /* If OP1 was not easily negatable, the constant may be OP0. */
5838 {
5845 }
5846 }
5851 /* If either OP1 or C are negative, this optimization is not safe for
5852 some of the division and remainder types while for others we need
5853 to change the code. */
5855 {
5863 }
5865 /* If it's a multiply or a division/modulus operation of a multiple
5866 of our constant, do the operation and verify it doesn't overflow. */
5869 {
5872 /* We allow the constant to overflow with wrapping semantics. */
5876 }
5877 else
5880 /* If we have an unsigned type, we cannot widen the operation since it
5881 will change the result if the original computation overflowed. */
5885 /* If we were able to eliminate our operation from the first side,
5886 apply our operation to the second side and reform the PLUS. */
5890 /* The last case is if we are a multiply. In that case, we can
5891 apply the distributive law to commute the multiply and addition
5892 if the multiplication of the constants doesn't overflow
5893 and overflow is defined. With undefined overflow
5894 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
5900 op1);
5905 /* We have a special case here if we are doing something like
5906 (C * 8) % 4 since we know that's zero. */
5909 /* If the multiplication can overflow we cannot optimize this. */
5913 {
5916 }
5918 /* ... fall through ... */
5922 /* If we can extract our operation from the LHS, do so and return a
5923 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5924 do something only if the second operand is a constant. */
5938 /* If these are the same operation types, we can associate them
5939 assuming no overflow. */
5941 {
5953 }
5955 /* If these operations "cancel" each other, we have the main
5956 optimizations of this pass, which occur when either constant is a
5957 multiple of the other, in which case we replace this with either an
5958 operation or CODE or TCODE.
5960 If we have an unsigned type, we cannot do this since it will change
5961 the result if the original computation overflowed. */
5968 {
5970 {
5977 }
5979 {
5986 }
5987 }
5992 }
5995 }
5996 \f
5997 /* Return a node which has the indicated constant VALUE (either 0 or
5998 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
5999 and is of the indicated TYPE. */
6001 tree
6003 {
6012 else
6014 }
6017 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6018 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6019 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6020 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6021 COND is the first argument to CODE; otherwise (as in the example
6022 given here), it is the second argument. TYPE is the type of the
6023 original expression. Return NULL_TREE if no simplification is
6024 possible. */
6026 static tree
6031 {
6041 {
6045 /* If this operand throws an expression, then it does not make
6046 sense to try to perform a logical or arithmetic operation
6047 involving it. */
6052 }
6053 else
6054 {
6059 }
6064 /* This transformation is only worthwhile if we don't have to wrap ARG
6065 in a SAVE_EXPR and the operation can be simplified without recursing
6066 on at least one of the branches once its pushed inside the COND_EXPR. */
6075 {
6079 else
6081 }
6083 {
6087 else
6089 }
6091 /* Check that we have simplified at least one of the branches. */
6096 }
6098 \f
6099 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6101 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6102 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6103 ADDEND is the same as X.
6105 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6106 and finite. The problematic cases are when X is zero, and its mode
6107 has signed zeros. In the case of rounding towards -infinity,
6108 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6109 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6111 bool
6113 {
6117 /* Don't allow the fold with -fsignaling-nans. */
6121 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6125 /* In a vector or complex, we would need to check the sign of all zeros. */
6129 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6133 /* The mode has signed zeros, and we have to honor their sign.
6134 In this situation, there is only one case we can return true for.
6135 X - 0 is the same as X unless rounding towards -infinity is
6136 supported. */
6138 }
6140 /* Subroutine of fold() that checks comparisons of built-in math
6141 functions against real constants.
6143 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6144 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6145 is the type of the result and ARG0 and ARG1 are the operands of the
6146 comparison. ARG1 must be a TREE_REAL_CST.
6148 The function returns the constant folded tree if a simplification
6149 can be made, and NULL_TREE otherwise. */
6151 static tree
6155 {
6156 REAL_VALUE_TYPE c;
6159 {
6165 {
6166 /* sqrt(x) < y is always false, if y is negative. */
6170 /* sqrt(x) > y is always true, if y is negative and we
6171 don't care about NaNs, i.e. negative values of x. */
6175 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6178 }
6180 {
6181 REAL_VALUE_TYPE c2;
6187 {
6188 /* sqrt(x) > y is x == +Inf, when y is very large. */
6193 /* sqrt(x) > y is always false, when y is very large
6194 and we don't care about infinities. */
6196 }
6198 /* sqrt(x) > c is the same as x > c*c. */
6201 }
6203 {
6204 REAL_VALUE_TYPE c2;
6210 {
6211 /* sqrt(x) < y is always true, when y is a very large
6212 value and we don't care about NaNs or Infinities. */
6216 /* sqrt(x) < y is x != +Inf when y is very large and we
6217 don't care about NaNs. */
6222 /* sqrt(x) < y is x >= 0 when y is very large and we
6223 don't care about Infinities. */
6228 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6233 dconst0)),
6236 c2)));
6237 }
6239 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6244 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6249 dconst0)),
6252 c2)));
6253 }
6254 }
6257 }
6259 /* Subroutine of fold() that optimizes comparisons against Infinities,
6260 either +Inf or -Inf.
6262 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6263 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6264 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6266 The function returns the constant folded tree if a simplification
6267 can be made, and NULL_TREE otherwise. */
6269 static tree
6272 {
6273 machine_mode mode;
6274 REAL_VALUE_TYPE max;
6275 tree temp;
6280 /* For negative infinity swap the sense of the comparison. */
6286 {
6288 /* x > +Inf is always false, if with ignore sNANs. */
6294 /* x <= +Inf is always true, if we don't case about NaNs. */
6298 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6304 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6310 /* x < +Inf is always equal to x <= DBL_MAX. */
6316 /* x != +Inf is always equal to !(x > DBL_MAX). */
6328 }
6331 }
6333 /* Subroutine of fold() that optimizes comparisons of a division by
6334 a nonzero integer constant against an integer constant, i.e.
6335 X/C1 op C2.
6337 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6338 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6339 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6341 The function returns the constant folded tree if a simplification
6342 can be made, and NULL_TREE otherwise. */
6344 static tree
6347 {
6355 /* We have to do this the hard way to detect unsigned overflow.
6356 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6362 {
6367 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6371 }
6373 {
6377 {
6396 }
6397 }
6398 else
6399 {
6400 /* A negative divisor reverses the relational operators. */
6406 {
6425 }
6426 }
6429 {
6450 {
6453 }
6458 {
6461 }
6466 {
6469 }
6474 {
6477 }
6482 }
6485 }
6488 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6489 equality/inequality test, then return a simplified form of the test
6490 using a sign testing. Otherwise return NULL. TYPE is the desired
6491 result type. */
6493 static tree
6496 tree result_type)
6497 {
6498 /* If this is testing a single bit, we can optimize the test. */
6502 {
6503 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6504 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6508 /* This is only a win if casting to a signed type is cheap,
6509 i.e. when arg00's type is not a partial mode. */
6512 {
6515 result_type,
6518 }
6519 }
6522 }
6524 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6525 equality/inequality test, then return a simplified form of
6526 the test using shifts and logical operations. Otherwise return
6527 NULL. TYPE is the desired result type. */
6529 tree
6532 {
6533 /* If this is testing a single bit, we can optimize the test. */
6537 {
6546 /* First, see if we can fold the single bit test into a sign-bit
6547 test. */
6549 result_type);
6553 /* Otherwise we have (A & C) != 0 where C is a single bit,
6554 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6555 Similarly for (A & C) == 0. */
6557 /* If INNER is a right shift of a constant and it plus BITNUM does
6558 not overflow, adjust BITNUM and INNER. */
6564 {
6567 }
6569 /* If we are going to be able to omit the AND below, we must do our
6570 operations as unsigned. If we must use the AND, we have a choice.
6571 Normally unsigned is faster, but for some machines signed is. */
6572 #ifdef LOAD_EXTEND_OP
6575 #else
6577 #endif
6593 /* Put the AND last so it can combine with more things. */
6596 /* Make sure to return the proper type. */
6600 }
6602 }
6604 /* Check whether we are allowed to reorder operands arg0 and arg1,
6605 such that the evaluation of arg1 occurs before arg0. */
6607 static bool
6609 {
6616 }
6618 /* Test whether it is preferable two swap two operands, ARG0 and
6619 ARG1, for example because ARG0 is an integer constant and ARG1
6620 isn't. If REORDER is true, only recommend swapping if we can
6621 evaluate the operands in reverse order. */
6623 bool
6625 {
6643 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6644 for commutative and comparison operators. Ensuring a canonical
6645 form allows the optimizers to find additional redundancies without
6646 having to explicitly check for both orderings. */
6652 /* Put SSA_NAMEs last. */
6658 /* Put variables last. */
6665 }
6667 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6668 ARG0 is extended to a wider type. */
6670 static tree
6673 {
6675 tree arg1_unw;
6684 #ifdef HAVE_canonicalize_funcptr_for_compare
6685 /* Disable this optimization if we're casting a function pointer
6686 type on targets that require function pointer canonicalization. */
6691 #endif
6698 /* If possible, express the comparison in the shorter mode. */
6718 /* If we are comparing with the integer that does not fit into the range
6719 of the shorter type, the result is known. */
6730 {
6757 }
6760 }
6762 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6763 ARG0 just the signedness is changed. */
6765 static tree
6768 {
6769 tree arg0_inner;
6779 #ifdef HAVE_canonicalize_funcptr_for_compare
6780 /* Disable this optimization if we're casting a function pointer
6781 type on targets that require function pointer canonicalization. */
6786 #endif
6807 else
6811 }
6814 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6815 means A >= Y && A != MAX, but in this case we know that
6816 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6818 static tree
6820 {
6827 else
6836 {
6839 }
6841 {
6844 }
6845 else
6852 {
6853 /* Convert the pointer types into integer before taking the difference. */
6857 }
6858 else
6865 }
6867 /* Fold a sum or difference of at least one multiplication.
6868 Returns the folded tree or NULL if no simplification could be made. */
6870 static tree
6873 {
6877 /* (A * C) +- (B * C) -> (A+-B) * C.
6878 (A * C) +- A -> A * (C+-1).
6879 We are most concerned about the case where C is a constant,
6880 but other combinations show up during loop reduction. Since
6881 it is not difficult, try all four possibilities. */
6884 {
6887 }
6889 {
6892 }
6893 else
6894 {
6895 /* We cannot generate constant 1 for fract. */
6900 }
6902 {
6905 }
6907 {
6909 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6910 the purpose of this canonicalization. */
6914 {
6917 }
6918 else
6920 }
6921 else
6922 {
6923 /* We cannot generate constant 1 for fract. */
6928 }
6940 /* No identical multiplicands; see if we can find a common
6941 power-of-two factor in non-power-of-two multiplies. This
6942 can help in multi-dimensional array access. */
6945 {
6948 tree maybe_same;
6952 /* Move min of absolute values to int11. */
6954 {
6959 }
6960 else
6964 /* The remainder should not be a constant, otherwise we
6965 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6966 increased the number of multiplications necessary. */
6968 {
6976 }
6977 }
6987 }
6989 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6990 specified by EXPR into the buffer PTR of length LEN bytes.
6991 Return the number of bytes placed in the buffer, or zero
6992 upon failure. */
6994 static int
6996 {
7010 {
7012 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7013 number of bytes. */
7017 {
7024 else
7026 }
7027 else
7032 }
7034 }
7037 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7038 specified by EXPR into the buffer PTR of length LEN bytes.
7039 Return the number of bytes placed in the buffer, or zero
7040 upon failure. */
7042 static int
7044 {
7048 FIXED_VALUE_TYPE value;
7064 }
7067 /* Subroutine of native_encode_expr. Encode the REAL_CST
7068 specified by EXPR into the buffer PTR of length LEN bytes.
7069 Return the number of bytes placed in the buffer, or zero
7070 upon failure. */
7072 static int
7074 {
7080 /* There are always 32 bits in each long, no matter the size of
7081 the hosts long. We handle floating point representations with
7082 up to 192 bits. */
7096 {
7101 {
7108 else
7110 }
7111 else
7117 }
7119 }
7121 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7122 specified by EXPR into the buffer PTR of length LEN bytes.
7123 Return the number of bytes placed in the buffer, or zero
7124 upon failure. */
7126 static int
7128 {
7130 tree part;
7145 }
7148 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7149 specified by EXPR into the buffer PTR of length LEN bytes.
7150 Return the number of bytes placed in the buffer, or zero
7151 upon failure. */
7153 static int
7155 {
7165 {
7167 {
7170 }
7181 }
7183 }
7186 /* Subroutine of native_encode_expr. Encode the STRING_CST
7187 specified by EXPR into the buffer PTR of length LEN bytes.
7188 Return the number of bytes placed in the buffer, or zero
7189 upon failure. */
7191 static int
7193 {
7195 HOST_WIDE_INT total_bytes;
7209 {
7212 {
7215 }
7218 }
7219 else
7222 }
7225 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7226 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7227 buffer PTR of length LEN bytes. If OFF is not -1 then start
7228 the encoding at byte offset OFF and encode at most LEN bytes.
7229 Return the number of bytes placed in the buffer, or zero upon failure. */
7231 int
7233 {
7235 {
7256 }
7257 }
7260 /* Subroutine of native_interpret_expr. Interpret the contents of
7261 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7262 If the buffer cannot be interpreted, return NULL_TREE. */
7264 static tree
7266 {
7276 }
7279 /* Subroutine of native_interpret_expr. Interpret the contents of
7280 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7281 If the buffer cannot be interpreted, return NULL_TREE. */
7283 static tree
7285 {
7287 double_int result;
7288 FIXED_VALUE_TYPE fixed_value;
7298 }
7301 /* Subroutine of native_interpret_expr. Interpret the contents of
7302 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7303 If the buffer cannot be interpreted, return NULL_TREE. */
7305 static tree
7307 {
7312 /* There are always 32 bits in each long, no matter the size of
7313 the hosts long. We handle floating point representations with
7314 up to 192 bits. */
7315 REAL_VALUE_TYPE r;
7326 {
7329 {
7336 else
7338 }
7339 else
7344 }
7348 }
7351 /* Subroutine of native_interpret_expr. Interpret the contents of
7352 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7353 If the buffer cannot be interpreted, return NULL_TREE. */
7355 static tree
7357 {
7372 }
7375 /* Subroutine of native_interpret_expr. Interpret the contents of
7376 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7377 If the buffer cannot be interpreted, return NULL_TREE. */
7379 static tree
7381 {
7394 {
7399 }
7401 }
7404 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7405 the buffer PTR of length LEN as a constant of type TYPE. For
7406 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7407 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7408 return NULL_TREE. */
7410 tree
7412 {
7414 {
7436 }
7437 }
7439 /* Returns true if we can interpret the contents of a native encoding
7440 as TYPE. */
7442 static bool
7444 {
7446 {
7459 }
7460 }
7462 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7463 TYPE at compile-time. If we're unable to perform the conversion
7464 return NULL_TREE. */
7466 static tree
7468 {
7469 /* We support up to 512-bit values (for V8DFmode). */
7473 /* Check that the host and target are sane. */
7482 }
7484 /* Build an expression for the address of T. Folds away INDIRECT_REF
7485 to avoid confusing the gimplify process. */
7487 tree
7489 {
7490 /* The size of the object is not relevant when talking about its address. */
7495 {
7500 }
7510 {
7515 }
7516 else
7520 }
7522 /* Build an expression for the address of T. */
7524 tree
7526 {
7530 }
7534 /* Fold a unary expression of code CODE and type TYPE with operand
7535 OP0. Return the folded expression if folding is successful.
7536 Otherwise, return NULL_TREE. */
7538 tree
7540 {
7541 tree tem;
7542 tree arg0;
7554 {
7557 {
7558 /* Don't use STRIP_NOPS, because signedness of argument type
7559 matters. */
7561 }
7562 else
7563 {
7564 /* Strip any conversions that don't change the mode. This
7565 is safe for every expression, except for a comparison
7566 expression because its signedness is derived from its
7567 operands.
7569 Note that this is done as an internal manipulation within
7570 the constant folder, in order to find the simplest
7571 representation of the arguments so that their form can be
7572 studied. In any cases, the appropriate type conversions
7573 should be put back in the tree that will get out of the
7574 constant folder. */
7576 }
7577 }
7580 {
7587 {
7601 /* If this was a conversion, and all we did was to move into
7602 inside the COND_EXPR, bring it back out. But leave it if
7603 it is a conversion from integer to integer and the
7604 result precision is no wider than a word since such a
7605 conversion is cheap and may be optimized away by combine,
7606 while it couldn't if it were outside the COND_EXPR. Then return
7607 so we don't get into an infinite recursion loop taking the
7608 conversion out and then back in. */
7620 && (INTEGRAL_TYPE_P
7633 }
7634 }
7637 {
7643 CASE_CONVERT:
7647 {
7648 /* If we have (type) (a CMP b) and type is an integral type, return
7649 new expression involving the new type. Canonicalize
7650 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7651 non-integral type.
7652 Do not fold the result as that would not simplify further, also
7653 folding again results in recursions. */
7663 }
7665 /* Handle (T *)&A.B.C for A being of type T and B and C
7666 living at offset zero. This occurs frequently in
7667 C++ upcasting and then accessing the base. */
7671 {
7673 tree offset;
7674 machine_mode mode;
7679 /* If the reference was to a (constant) zero offset, we can use
7680 the address of the base if it has the same base type
7681 as the result type and the pointer type is unqualified. */
7688 }
7692 /* Detect assigning a bitfield. */
7694 && DECL_BIT_FIELD
7696 {
7697 /* Don't leave an assignment inside a conversion
7698 unless assigning a bitfield. */
7700 /* First do the assignment, then return converted constant. */
7705 }
7707 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7708 constants (if x has signed type, the sign bit cannot be set
7709 in c). This folds extension into the BIT_AND_EXPR.
7710 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7711 very likely don't have maximal range for their precision and this
7712 transformation effectively doesn't preserve non-maximal ranges. */
7716 {
7727 <= HOST_BITS_PER_WIDE_INT
7729 {
7733 cst &= HOST_WIDE_INT_M1U
7736 #ifdef LOAD_EXTEND_OP
7738 && !flag_syntax_only
7741 {
7745 }
7746 #endif
7747 }
7749 {
7754 }
7755 }
7757 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7758 when one of the new casts will fold away. Conservatively we assume
7759 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7766 {
7770 return fold_build_pointer_plus_loc
7772 }
7774 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7775 of the same precision, and X is an integer type not narrower than
7776 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7782 {
7788 }
7790 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7791 type of X and Y (integer types only). */
7796 {
7797 /* Be careful not to introduce new overflows. */
7798 tree mult_type;
7801 else
7805 {
7812 }
7813 }
7843 /* Convert fabs((double)float) into (double)fabsf(float). */
7846 {
7852 targ0));
7853 }
7854 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7858 /* Strip sign ops from argument. */
7860 {
7865 }
7872 {
7878 }
7880 {
7885 }
7893 /* Convert ~ (-A) to A - 1. */
7898 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7907 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7922 /* Perform BIT_NOT_EXPR on each element individually. */
7924 {
7926 tree elem;
7931 {
7937 }
7940 }
7944 {
7951 }
7957 /* Note that the operand of this must be an int
7958 and its values must be 0 or 1.
7959 ("true" is a fixed value perhaps depending on the language,
7960 but we don't handle values other than 1 correctly yet.) */
7972 {
7980 }
7982 {
7987 }
7989 {
7993 {
8002 }
8003 }
8012 {
8020 }
8022 {
8026 }
8028 {
8032 {
8041 }
8042 }
8046 /* Fold *&X to X if X is an lvalue. */
8048 {
8055 }
8062 {
8081 else
8085 {
8089 }
8092 }
8097 {
8111 {
8116 }
8119 {
8123 }
8126 }
8131 }
8134 /* If the operation was a conversion do _not_ mark a resulting constant
8135 with TREE_OVERFLOW if the original constant was not. These conversions
8136 have implementation defined behavior and retaining the TREE_OVERFLOW
8137 flag here would confuse later passes such as VRP. */
8138 tree
8141 {
8150 }
8152 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8153 operands OP0 and OP1. LOC is the location of the resulting expression.
8154 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8155 Return the folded expression if folding is successful. Otherwise,
8156 return NULL_TREE. */
8157 static tree
8160 {
8161 tree tem;
8163 /* We only do these simplifications if we are optimizing. */
8167 /* Check for things like (A || B) && (A || C). We can convert this
8168 to A || (B && C). Note that either operator can be any of the four
8169 truth and/or operations and the transformation will still be
8170 valid. Also note that we only care about order for the
8171 ANDIF and ORIF operators. If B contains side effects, this
8172 might change the truth-value of A. */
8179 {
8199 /* This case if tricky because we must either have commutative
8200 operators or else A10 must not have side-effects. */
8206 a01);
8207 }
8209 /* See if we can build a range comparison. */
8215 {
8219 }
8223 {
8227 }
8229 /* Check for the possibility of merging component references. If our
8230 lhs is another similar operation, try to merge its rhs with our
8231 rhs. Then try to merge our lhs and rhs. */
8245 {
8252 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8253 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8254 We don't want to pack more than two leafs to a non-IF AND/OR
8255 expression.
8256 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8257 equal to IF-CODE, then we don't want to add right-hand operand.
8258 If the inner right-hand side of left-hand operand has
8259 side-effects, or isn't simple, then we can't add to it,
8260 as otherwise we might destroy if-sequence. */
8263 /* Needed for sequence points to handle trappings, and
8264 side-effects. */
8266 {
8268 arg1);
8270 tem);
8271 }
8272 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8273 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8276 /* Needed for sequence points to handle trappings, and
8277 side-effects. */
8279 {
8284 }
8285 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8286 into (A OR B).
8287 For sequence point consistancy, we need to check for trapping,
8288 and side-effects. */
8292 }
8295 }
8297 /* Fold a binary expression of code CODE and type TYPE with operands
8298 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8299 Return the folded expression if folding is successful. Otherwise,
8300 return NULL_TREE. */
8302 static tree
8304 {
8311 else
8314 /* MIN (MAX (a, b), b) == b. */
8319 /* MIN (MAX (b, a), b) == b. */
8325 /* MIN (a, MAX (a, b)) == a. */
8331 /* MIN (a, MAX (b, a)) == a. */
8338 }
8340 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8341 by changing CODE to reduce the magnitude of constants involved in
8342 ARG0 of the comparison.
8343 Returns a canonicalized comparison tree if a simplification was
8344 possible, otherwise returns NULL_TREE.
8345 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8346 valid if signed overflow is undefined. */
8348 static tree
8352 {
8358 /* Match A +- CST code arg1 and CST code arg1. We can change the
8359 first form only if overflow is undefined. */
8361 /* In principle pointers also have undefined overflow behavior,
8362 but that causes problems elsewhere. */
8370 /* Identify the constant in arg0 and its sign. */
8373 else
8377 /* Overflowed constants and zero will cause problems. */
8382 /* See if we can reduce the magnitude of the constant in
8383 arg0 by changing the comparison code. */
8385 {
8386 /* CST <= arg1 -> CST-1 < arg1. */
8389 /* -CST < arg1 -> -CST-1 <= arg1. */
8392 /* CST > arg1 -> CST-1 >= arg1. */
8395 /* -CST >= arg1 -> -CST-1 > arg1. */
8398 else
8400 /* arg1 code' CST' might be more canonical. */
8402 }
8403 else
8404 {
8405 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8409 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8413 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8417 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8421 else
8424 }
8426 /* Now build the constant reduced in magnitude. But not if that
8427 would produce one outside of its types range. */
8435 /* We cannot swap the comparison here as that would cause us to
8436 endlessly recurse. */
8445 /* If swapping might yield to a more canonical form, do so. */
8448 else
8450 }
8452 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8453 overflow further. Try to decrease the magnitude of constants involved
8454 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8455 and put sole constants at the second argument position.
8456 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8458 static tree
8461 {
8462 tree t;
8467 /* Try canonicalization by simplifying arg0. */
8472 {
8476 }
8478 /* Try canonicalization by simplifying arg1 using the swapped
8479 comparison. */
8487 }
8489 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8490 space. This is used to avoid issuing overflow warnings for
8491 expressions like &p->x which can not wrap. */
8493 static bool
8495 {
8502 wide_int wi_offset;
8508 else
8524 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8525 array. */
8527 {
8528 HOST_WIDE_INT base_size;
8533 }
8536 }
8538 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8539 kind INTEGER_CST. This makes sure to properly sign-extend the
8540 constant. */
8542 static HOST_WIDE_INT
8544 {
8550 }
8552 /* Subroutine of fold_binary. This routine performs all of the
8553 transformations that are common to the equality/inequality
8554 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8555 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8556 fold_binary should call fold_binary. Fold a comparison with
8557 tree code CODE and type TYPE with operands OP0 and OP1. Return
8558 the folded comparison or NULL_TREE. */
8560 static tree
8563 {
8573 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8580 {
8581 const enum tree_code
8588 /* If the constant operation overflowed this can be
8589 simplified as a comparison against INT_MAX/INT_MIN. */
8592 {
8596 /* Get the sign of the constant on the lhs if the
8597 operation were VARIABLE + CONST1. */
8601 /* The sign of the constant determines if we overflowed
8602 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8603 Canonicalize to the INT_MIN overflow by swapping the comparison
8604 if necessary. */
8608 /* We now can look at the canonicalized case
8609 VARIABLE + 1 CODE2 INT_MIN
8610 and decide on the result. */
8612 {
8616 return
8622 return
8627 }
8628 }
8629 else
8630 {
8633 "when changing X +- C1 cmp C2 to "
8635 WARN_STRICT_OVERFLOW_COMPARISON);
8637 }
8638 }
8640 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8642 && equality_code
8644 {
8645 /* ??? The transformation is valid for the other operators if overflow
8646 is undefined for the type, but performing it here badly interacts
8647 with the transformation in fold_cond_expr_with_comparison which
8648 attempts to synthetize ABS_EXPR. */
8652 WARN_STRICT_OVERFLOW_COMPARISON);
8655 }
8657 /* For comparisons of pointers we can decompose it to a compile time
8658 comparison of the base objects and the offsets into the object.
8659 This requires at least one operand being an ADDR_EXPR or a
8660 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8666 {
8669 machine_mode mode;
8673 /* Get base and offset for the access. Strip ADDR_EXPR for
8674 get_inner_reference, but put it back by stripping INDIRECT_REF
8675 off the base object if possible. indirect_baseN will be true
8676 if baseN is not an address but refers to the object itself. */
8679 {
8685 else
8687 }
8689 {
8693 {
8696 }
8699 {
8704 {
8707 }
8708 }
8709 }
8713 {
8719 else
8721 }
8723 {
8727 {
8730 }
8733 {
8738 {
8741 }
8742 }
8743 }
8745 /* A local variable can never be pointed to by
8746 the default SSA name of an incoming parameter. */
8748 && indirect_base0
8751 && !indirect_base1
8756 && indirect_base1
8759 && !indirect_base0
8763 {
8768 }
8769 /* If we have equivalent bases we might be able to simplify. */
8772 {
8773 /* We can fold this expression to a constant if the non-constant
8774 offset parts are equal. */
8783 {
8789 "occur when comparing P +- C1 with "
8791 WARN_STRICT_OVERFLOW_CONDITIONAL);
8794 {
8808 }
8809 }
8810 /* We can simplify the comparison to a comparison of the variable
8811 offset parts if the constant offset parts are equal.
8812 Be careful to use signed sizetype here because otherwise we
8813 mess with array offsets in the wrong way. This is possible
8814 because pointer arithmetic is restricted to retain within an
8815 object and overflow on pointer differences is undefined as of
8816 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8818 && (equality_code
8821 {
8822 /* By converting to signed sizetype we cover middle-end pointer
8823 arithmetic which operates on unsigned pointer types of size
8824 type size and ARRAY_REF offsets which are properly sign or
8825 zero extended from their type in case it is narrower than
8826 sizetype. */
8829 else
8833 else
8840 "occur when comparing P +- C1 with "
8842 WARN_STRICT_OVERFLOW_COMPARISON);
8845 }
8846 }
8847 /* For non-equal bases we can simplify if they are addresses
8848 of local binding decls or constants. */
8850 /* We know that !operand_equal_p (base0, base1, 0)
8851 because the if condition was false. But make
8852 sure two decls are not the same. */
8866 {
8873 }
8874 /* For equal offsets we can simplify to a comparison of the
8875 base addresses. */
8877 && (indirect_base0
8879 && (indirect_base1
8884 {
8890 }
8891 }
8893 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8894 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8895 the resulting offset is smaller in absolute value than the
8896 original one and has the same sign. */
8904 {
8909 tree cst;
8911 "occur when combining constants around "
8914 /* Put the constant on the side where it doesn't overflow and is
8915 of lower absolute value and of same sign than before. */
8922 {
8925 variable1,
8929 }
8937 {
8943 variable2);
8944 }
8945 }
8947 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8948 signed arithmetic case. That form is created by the compiler
8949 often enough for folding it to be of value. One example is in
8950 computing loop trip counts after Operator Strength Reduction. */
8956 {
8962 /* Handle unfolded multiplication by zero. */
8967 "eliminating multiplication in comparison "
8969 WARN_STRICT_OVERFLOW_COMPARISON);
8971 /* If const1 is negative we swap the sense of the comparison. */
8976 }
8983 {
8991 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8997 /* (-a) CMP (-b) -> b CMP a */
9004 {
9005 REAL_VALUE_TYPE cst;
9008 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9015 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9016 /* a CMP (-0) -> a CMP 0 */
9021 /* x != NaN is always true, other ops are always false. */
9024 {
9027 }
9029 /* Fold comparisons against infinity. */
9032 {
9036 }
9037 }
9039 /* If this is a comparison of a real constant with a PLUS_EXPR
9040 or a MINUS_EXPR of a real constant, we can convert it into a
9041 comparison with a revised real constant as long as no overflow
9042 occurs when unsafe_math_optimizations are enabled. */
9054 /* Likewise, we can simplify a comparison of a real constant with
9055 a MINUS_EXPR whose first operand is also a real constant, i.e.
9056 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9057 floating-point types only if -fassociative-math is set. */
9063 arg1))
9068 /* Fold comparisons against built-in math functions. */
9070 && flag_unsafe_math_optimizations
9072 {
9076 {
9080 }
9081 }
9082 }
9086 {
9087 /* If we are widening one operand of an integer comparison,
9088 see if the other operand is similarly being widened. Perhaps we
9089 can do the comparison in the narrower type. */
9094 /* Or if we are changing signedness. */
9098 }
9100 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9101 constant, we can simplify it. */
9106 {
9110 }
9112 /* Simplify comparison of something with itself. (For IEEE
9113 floating-point, we can only do some of these simplifications.) */
9115 {
9117 {
9132 /* For NE, we can only do this simplification if integer
9133 or we don't honor IEEE floating point NaNs. */
9137 /* ... fall through ... */
9143 }
9144 }
9146 /* If we are comparing an expression that just has comparisons
9147 of two integer values, arithmetic expressions of those comparisons,
9148 and constants, we can simplify it. There are only three cases
9149 to check: the two values can either be equal, the first can be
9150 greater, or the second can be greater. Fold the expression for
9151 those three values. Since each value must be 0 or 1, we have
9152 eight possibilities, each of which corresponds to the constant 0
9153 or 1 or one of the six possible comparisons.
9155 This handles common cases like (a > b) == 0 but also handles
9156 expressions like ((x > y) - (y > x)) > 0, which supposedly
9157 occur in macroized code. */
9160 {
9165 /* Don't handle degenerate cases here; they should already
9166 have been handled anyway. */
9175 {
9179 /* We can't just pass T to eval_subst in case cval1 or cval2
9180 was the same as ARG1. */
9182 tree high_result
9186 arg1);
9187 tree equal_result
9191 arg1);
9192 tree low_result
9196 arg1);
9198 /* All three of these results should be 0 or 1. Confirm they are.
9199 Then use those values to select the proper code to use. */
9204 {
9205 /* Make a 3-bit mask with the high-order bit being the
9206 value for `>', the next for '=', and the low for '<'. */
9210 {
9212 /* Always false. */
9233 /* Always true. */
9235 }
9238 {
9242 }
9244 }
9245 }
9246 }
9248 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9249 into a single range test. */
9257 {
9261 }
9263 /* Fold ~X op ~Y as Y op X. */
9266 {
9272 }
9274 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9277 {
9283 }
9286 }
9289 /* Subroutine of fold_binary. Optimize complex multiplications of the
9290 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9291 argument EXPR represents the expression "z" of type TYPE. */
9293 static tree
9295 {
9300 {
9303 }
9305 {
9308 }
9309 else
9310 {
9314 }
9323 }
9326 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9327 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9328 guarantees that P and N have the same least significant log2(M) bits.
9329 N is not otherwise constrained. In particular, N is not normalized to
9330 0 <= N < M as is common. In general, the precise value of P is unknown.
9331 M is chosen as large as possible such that constant N can be determined.
9333 Returns M and sets *RESIDUE to N.
9335 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9336 account. This is not always possible due to PR 35705.
9337 */
9339 static unsigned HOST_WIDE_INT
9342 {
9349 {
9354 }
9356 {
9364 allow_func_align);
9370 {
9373 }
9375 {
9378 {
9381 /* Compute the greatest power-of-2 divisor of op1. */
9385 /* If align is non-zero and less than *modulus, replace
9386 *modulus with align., If align is 0, then either op1 is 0
9387 or the greatest power-of-2 divisor of op1 doesn't fit in an
9388 unsigned HOST_WIDE_INT. In either case, no additional
9389 constraint is imposed. */
9394 }
9395 }
9396 }
9398 /* If we get here, we were unable to determine anything useful about the
9399 expression. */
9401 }
9403 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9404 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9406 static bool
9408 {
9412 {
9415 }
9417 {
9423 else
9425 }
9426 else
9432 }
9434 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9435 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9436 NULL_TREE otherwise. */
9438 static tree
9440 {
9457 {
9461 }
9464 {
9470 }
9471 else
9473 }
9475 /* Try to fold a pointer difference of type TYPE two address expressions of
9476 array references AREF0 and AREF1 using location LOC. Return a
9477 simplified expression for the difference or NULL_TREE. */
9479 static tree
9482 {
9487 /* If the bases are array references as well, recurse. If the bases
9488 are pointer indirections compute the difference of the pointers.
9489 If the bases are equal, we are set. */
9492 && (base_offset
9500 {
9506 base_offset,
9509 }
9511 }
9513 /* If the real or vector real constant CST of type TYPE has an exact
9514 inverse, return it, else return NULL. */
9516 static tree
9518 {
9519 REAL_VALUE_TYPE r;
9521 machine_mode mode;
9525 {
9541 {
9546 }
9552 }
9553 }
9555 /* Mask out the tz least significant bits of X of type TYPE where
9556 tz is the number of trailing zeroes in Y. */
9557 static wide_int
9559 {
9564 }
9566 /* Return true when T is an address and is known to be nonzero.
9567 For floating point we further ensure that T is not denormal.
9568 Similar logic is present in nonzero_address in rtlanal.h.
9570 If the return value is based on the assumption that signed overflow
9571 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9572 change *STRICT_OVERFLOW_P. */
9574 static bool
9576 {
9580 /* Doing something useful for floating point would need more work. */
9586 {
9589 strict_overflow_p);
9595 strict_overflow_p);
9603 }
9606 {
9609 strict_overflow_p);
9617 strict_overflow_p);
9632 strict_overflow_p);
9636 strict_overflow_p);
9639 {
9651 }
9655 }
9657 }
9659 /* Return true when T is an address and is known to be nonzero.
9660 Handle warnings about undefined signed overflow. */
9662 static bool
9664 {
9671 "determining that expression is always "
9673 WARN_STRICT_OVERFLOW_MISC);
9675 }
9677 /* Fold a binary expression of code CODE and type TYPE with operands
9678 OP0 and OP1. LOC is the location of the resulting expression.
9679 Return the folded expression if folding is successful. Otherwise,
9680 return NULL_TREE. */
9682 tree
9685 {
9700 /* Strip any conversions that don't change the mode. This is
9701 safe for every expression, except for a comparison expression
9702 because its signedness is derived from its operands. So, in
9703 the latter case, only strip conversions that don't change the
9704 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9705 preserved.
9707 Note that this is done as an internal manipulation within the
9708 constant folder, in order to find the simplest representation
9709 of the arguments so that their form can be studied. In any
9710 cases, the appropriate type conversions should be put back in
9711 the tree that will get out of the constant folder. */
9714 {
9717 }
9718 else
9719 {
9722 }
9724 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9725 constant but we can't do arithmetic on them. */
9733 {
9735 {
9736 /* Make sure type and arg0 have the same saturating flag. */
9740 }
9743 else
9747 {
9751 }
9752 }
9754 /* If this is a commutative operation, and ARG0 is a constant, move it
9755 to ARG1 to reduce the number of tests below. */
9760 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9761 to ARG1 to reduce the number of tests below. */
9770 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9772 First check for cases where an arithmetic operation is applied to a
9773 compound, conditional, or comparison operation. Push the arithmetic
9774 operation inside the compound or conditional to see if any folding
9775 can then be done. Convert comparison to conditional for this purpose.
9776 The also optimizes non-constant cases that used to be done in
9777 expand_expr.
9779 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9780 one of the operands is a comparison and the other is a comparison, a
9781 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9782 code below would make the expression more complex. Change it to a
9783 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9784 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9797 {
9801 boolean_type_node,
9809 }
9813 {
9815 {
9820 tem);
9821 }
9824 {
9829 tem);
9830 }
9835 {
9841 }
9846 {
9852 }
9853 }
9856 {
9858 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9861 {
9867 }
9869 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9872 {
9873 tree base;
9874 HOST_WIDE_INT coffset;
9883 }
9888 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9894 arg1),
9896 arg0)));
9898 /* PTR_CST +p CST -> CST1 */
9907 {
9908 /* X + (X / CST) * -CST is X % CST. */
9913 {
9922 cst0));
9923 }
9924 }
9926 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9927 one. Make sure the type is not saturating and has the signedness of
9928 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9929 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9936 {
9940 }
9943 {
9944 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9945 with a constant, and the two constants have no bits in common,
9946 we should treat this as a BIT_IOR_EXPR since this may produce more
9947 simplifications. */
9954 {
9957 }
9959 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9960 (plus (plus (mult) (mult)) (foo)) so that we can
9961 take advantage of the factoring cases below. */
9969 {
9975 else
9988 parg0),
9990 marg)),
9994 return
10000 parg1)));
10001 }
10002 }
10003 else
10004 {
10005 /* See if ARG1 is zero and X + ARG1 reduces to X. */
10009 /* Likewise if the operands are reversed. */
10013 /* Convert X + -C into X - C. */
10016 {
10022 }
10024 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10025 to __complex__ ( x, y ). This is not the same for SNaNs or
10026 if signed zeros are involved. */
10030 {
10037 {
10041 {
10047 }
10049 {
10055 }
10056 }
10057 }
10065 /* Convert x+x into x*2.0. */
10071 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10072 We associate floats only if the user has specified
10073 -fassociative-math. */
10077 {
10082 {
10083 tree tree0;
10086 }
10087 }
10088 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10089 We associate floats only if the user has specified
10090 -fassociative-math. */
10094 {
10099 {
10100 tree tree0;
10103 }
10104 }
10105 }
10107 bit_rotate:
10108 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10109 is a rotate of A by C1 bits. */
10110 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10111 is a rotate of A by B bits. */
10112 {
10114 tree rtype;
10123 /* Only create rotates in complete modes. Other cases are not
10124 expanded properly. */
10127 {
10141 {
10147 }
10149 {
10157 element_precision
10161 return
10164 ? LROTATE_EXPR
10168 }
10170 {
10178 element_precision
10182 return fold_convert_loc
10185 ? LROTATE_EXPR
10189 }
10190 }
10191 }
10193 associate:
10194 /* In most languages, can't associate operations on floats through
10195 parentheses. Rather than remember where the parentheses were, we
10196 don't associate floats at all, unless the user has specified
10197 -fassociative-math.
10198 And, we need to make sure type is not saturating. */
10202 {
10208 /* Split both trees into variables, constants, and literals. Then
10209 associate each group together, the constants with literals,
10210 then the result with variables. This increases the chances of
10211 literals being recombined later and of generating relocatable
10212 expressions for the sum of a constant and literal. */
10217 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10221 /* With undefined overflow prefer doing association in a type
10222 which wraps on overflow, if that is one of the operand types. */
10225 {
10233 }
10235 /* With undefined overflow we can only associate constants with one
10236 variable, and constants whose association doesn't overflow. */
10239 {
10241 {
10259 /* The only case we can still associate with two variables
10260 is if they are the same, modulo negation and bit-pattern
10261 preserving conversions. */
10264 }
10265 }
10267 /* Only do something if we found more than two objects. Otherwise,
10268 nothing has changed and we risk infinite recursion. */
10274 {
10286 /* Preserve the MINUS_EXPR if the negative part of the literal is
10287 greater than the positive part. Otherwise, the multiplicative
10288 folding code (i.e extract_muldiv) may be fooled in case
10289 unsigned constants are subtracted, like in the following
10290 example: ((X*2 + 4) - 8U)/2. */
10292 {
10296 {
10300 }
10301 else
10302 {
10306 }
10307 }
10309 /* Don't introduce overflows through reassociation. */
10316 {
10318 return
10322 else
10323 {
10326 return
10330 }
10331 }
10334 return
10337 }
10338 }
10343 /* Pointer simplifications for subtraction, simple reassociations. */
10345 {
10346 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10349 {
10359 }
10360 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10362 {
10369 }
10370 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10371 simplifies. */
10373 {
10380 arg10);
10383 }
10384 }
10385 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10394 /* Convert -A - 1 to ~A. */
10402 /* Convert -1 - A to ~A. */
10408 /* X - (X / Y) * Y is X % Y. */
10416 return
10422 {
10426 /* Fold A - (A & B) into ~B & A. */
10429 {
10431 {
10438 }
10440 {
10447 }
10448 }
10450 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10451 any power of 2 minus 1. */
10456 {
10462 {
10466 }
10467 }
10468 }
10470 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10474 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10475 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10476 (-ARG1 + ARG0) reduces to -ARG1. */
10480 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10481 __complex__ ( x, -y ). This is not the same for SNaNs or if
10482 signed zeros are involved. */
10486 {
10493 {
10497 {
10499 arg1r ? arg1r
10504 }
10506 {
10510 arg1i ? arg1i
10513 }
10514 }
10515 }
10517 /* A - B -> A + (-B) if B is easily negatable. */
10521 /* Avoid this transformation if B is a positive REAL_CST. */
10530 /* Try folding difference of addresses. */
10531 {
10532 HOST_WIDE_INT diff;
10538 }
10540 /* Fold &a[i] - &a[j] to i-j. */
10545 {
10551 }
10554 && flag_unsafe_math_optimizations
10560 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10561 one. Make sure the type is not saturating and has the signedness of
10562 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10563 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10570 {
10574 }
10579 /* (-A) * (-B) -> A * B */
10594 {
10595 /* Transform x * -1 into -x. Make sure to do the negation
10596 on the original operand with conversions not stripped
10597 because we can only strip non-sign-changing conversions. */
10600 /* Transform x * -C into -x * C if x is easily negatable. */
10609 tem);
10611 /* (a * (1 << b)) is (a << b) */
10621 /* (A + A) * C -> A * 2 * C */
10633 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10634 sign-changing only. */
10644 {
10647 "occur when simplifying "
10649 WARN_STRICT_OVERFLOW_MISC);
10651 }
10653 /* Optimize z * conj(z) for integer complex numbers. */
10660 }
10661 else
10662 {
10663 /* Maybe fold x * 0 to 0. The expressions aren't the same
10664 when x is NaN, since x * 0 is also NaN. Nor are they the
10665 same in modes with signed zeros, since multiplying a
10666 negative value by 0 gives -0, not +0. */
10671 /* In IEEE floating point, x*1 is not equivalent to x for snans.
10672 Likewise for complex arithmetic with signed zeros. */
10679 /* Transform x * -1.0 into -x. */
10686 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10687 the result for floating point types due to rounding so it is applied
10688 only if -fassociative-math was specify. */
10693 {
10695 arg1);
10699 }
10701 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10703 {
10706 {
10709 }
10710 }
10712 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10713 This is not the same for NaNs or if signed zeros are
10714 involved. */
10720 {
10723 return
10729 return
10734 }
10736 /* Optimize z * conj(z) for floating point complex numbers.
10737 Guarded by flag_unsafe_math_optimizations as non-finite
10738 imaginary components don't produce scalar results. */
10749 {
10753 /* Optimizations of root(...)*root(...). */
10755 {
10760 /* Optimize sqrt(x)*sqrt(x) as x. */
10766 /* Optimize root(x)*root(y) as root(x*y). */
10770 }
10772 /* Optimize expN(x)*expN(y) as expN(x+y). */
10774 {
10780 }
10782 /* Optimizations of pow(...)*pow(...). */
10786 {
10792 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10794 {
10799 }
10801 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10803 {
10808 }
10809 }
10811 /* Optimize tan(x)*cos(x) as sin(x). */
10820 {
10826 }
10828 /* Optimize x*pow(x,c) as pow(x,c+1). */
10832 {
10838 {
10840 REAL_VALUE_TYPE c;
10841 tree arg;
10847 }
10848 }
10850 /* Optimize pow(x,c)*x as pow(x,c+1). */
10854 {
10860 {
10862 REAL_VALUE_TYPE c;
10863 tree arg;
10869 }
10870 }
10872 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10874 && optimize
10876 {
10880 {
10883 }
10884 }
10885 }
10886 }
10890 bit_ior:
10891 /* ~X | X is -1. */
10894 {
10898 }
10900 /* X | ~X is -1. */
10903 {
10907 }
10909 /* Canonicalize (X & C1) | C2. */
10913 {
10918 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10926 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10931 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10932 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10933 mode which allows further optimizations. */
10938 {
10942 {
10945 }
10946 }
10953 c3)),
10954 arg1);
10955 }
10957 /* (X & ~Y) | (~X & Y) is X ^ Y */
10960 {
10977 }
10983 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10985 This results in more efficient code for machines without a NAND
10986 instruction. Combine will canonicalize to the first form
10987 which will allow use of NAND instructions provided by the
10988 backend if they exist. */
10991 {
10992 return
10999 }
11001 /* See if this can be simplified into a rotate first. If that
11002 is unsuccessful continue in the association code. */
11006 /* ~X ^ X is -1. */
11009 {
11013 }
11015 /* X ^ ~X is -1. */
11018 {
11022 }
11024 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11025 with a constant, and the two constants have no bits in common,
11026 we should treat this as a BIT_IOR_EXPR since this may produce more
11027 simplifications. */
11034 {
11037 }
11039 /* (X | Y) ^ X -> Y & ~ X*/
11042 {
11045 arg1);
11050 }
11052 /* (Y | X) ^ X -> Y & ~ X*/
11055 {
11058 arg1);
11063 }
11065 /* X ^ (X | Y) -> Y & ~ X*/
11068 {
11071 arg0);
11076 }
11078 /* X ^ (Y | X) -> Y & ~ X*/
11081 {
11084 arg0);
11089 }
11091 /* Convert ~X ^ ~Y to X ^ Y. */
11100 /* Convert ~X ^ C to X ^ ~C. */
11108 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11116 /* Fold (X & Y) ^ Y as ~X & Y. */
11119 {
11124 }
11125 /* Fold (X & Y) ^ X as ~Y & X. */
11129 {
11134 }
11135 /* Fold X ^ (X & Y) as X & ~Y. */
11138 {
11143 }
11144 /* Fold X ^ (Y & X) as ~Y & X. */
11148 {
11153 }
11155 /* See if this can be simplified into a rotate first. If that
11156 is unsuccessful continue in the association code. */
11160 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11168 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11176 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11181 {
11182 tree tem2;
11189 }
11190 /* Fold ~X & 1 as (X & 1) == 0. */
11194 {
11195 tree tem2;
11202 }
11203 /* Fold !X & 1 as X == 0. */
11206 {
11210 }
11212 /* Fold (X ^ Y) & Y as ~X & Y. */
11215 {
11220 }
11221 /* Fold (X ^ Y) & X as ~Y & X. */
11225 {
11230 }
11231 /* Fold X & (X ^ Y) as X & ~Y. */
11234 {
11239 }
11240 /* Fold X & (Y ^ X) as ~Y & X. */
11244 {
11249 }
11251 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11252 multiple of 1 << CST. */
11254 {
11261 }
11263 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11264 bits from CST2. */
11268 {
11276 {
11277 /* Avoid the transform if arg1 is a mask of some
11278 mode which allows further optimizations. */
11285 }
11286 }
11288 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11289 ((A & N) + B) & M -> (A + B) & M
11290 Similarly if (N & M) == 0,
11291 ((A | N) + B) & M -> (A + B) & M
11292 and for - instead of + (or unary - instead of +)
11293 and/or ^ instead of |.
11294 If B is constant and (B & M) == 0, fold into A & M. */
11296 {
11305 {
11308 wide_int cst0;
11310 /* Now we know that arg0 is (C + D) or (C - D) or
11311 -C and arg1 (M) is == (1LL << cst) - 1.
11312 Store C into PMOP[0] and D into PMOP[1]. */
11316 {
11319 }
11326 {
11336 {
11339 }
11342 /* If C or D is of the form (A & N) where
11343 (N & M) == M, or of the form (A | N) or
11344 (A ^ N) where (N & M) == 0, replace it with A. */
11348 /* If C or D is a N where (N & M) == 0, it can be
11349 omitted (assumed 0). */
11357 }
11359 /* Only build anything new if we optimized one or both arguments
11360 above. */
11364 {
11367 {
11368 /* Perform the operations in a type that has defined
11369 overflow behavior. */
11375 }
11380 {
11388 else
11390 }
11393 else
11396 /* TEM is now the new binary +, - or unary - replacement. */
11400 }
11401 }
11402 }
11407 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11410 {
11415 return
11417 }
11419 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11421 This results in more efficient code for machines without a NOR
11422 instruction. Combine will canonicalize to the first form
11423 which will allow use of NOR instructions provided by the
11424 backend if they exist. */
11427 {
11434 }
11436 /* If arg0 is derived from the address of an object or function, we may
11437 be able to fold this expression using the object or function's
11438 alignment. */
11440 {
11447 /* This works because modulus is a power of 2. If this weren't the
11448 case, we'd have to replace it by its greatest power-of-2
11449 divisor: modulus & -modulus. */
11452 }
11454 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11455 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11456 if the new mask might be further optimized. */
11465 {
11476 {
11479 /* See if more bits can be proven as zero because of
11480 zero extension. */
11483 {
11488 {
11490 /* See if we can shorten the right shift. */
11493 /* Otherwise X >> C1 is all zeros, so we'll optimize
11494 it into (X, 0) later on by making sure zerobits
11495 is all ones. */
11496 }
11497 }
11500 {
11503 }
11504 /* For arithmetic shift if sign bit could be set, zerobits
11505 can contain actually sign bits, so no transformation is
11506 possible, unless MASK masks them all away. In that
11507 case the shift needs to be converted into logical shift. */
11510 {
11513 else
11515 }
11516 }
11518 /* ((X << 16) & 0xff00) is (X, 0). */
11525 {
11526 /* Only do the transformation if NEWMASK is some integer
11527 mode's mask. */
11534 {
11535 tree newmaskt;
11538 {
11544 }
11545 else
11550 }
11551 }
11552 }
11557 /* Don't touch a floating-point divide by zero unless the mode
11558 of the constant can represent infinity. */
11564 /* Optimize A / A to 1.0 if we don't care about
11565 NaNs or Infinities. Skip the transformation
11566 for non-real operands. */
11571 {
11575 }
11577 /* The complex version of the above A / A optimization. */
11580 {
11584 {
11586 /* omit_two_operands will call fold_convert for us. */
11588 }
11589 }
11591 /* (-A) / (-B) -> A / B */
11601 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11606 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11612 /* If ARG1 is a constant, we can convert this to a multiply by the
11613 reciprocal. This does not have the same rounding properties,
11614 so only do this if -freciprocal-math. We can actually
11615 always safely do it if ARG1 is a power of two, but it's hard to
11616 tell if it is or not in a portable manner. */
11623 {
11627 /* Find the reciprocal if optimizing and the result is exact.
11628 TODO: Complex reciprocal not implemented. */
11630 {
11635 }
11636 }
11637 /* Convert A/B/C to A/(B*C). */
11644 /* Convert A/(B/C) to (A/B)*C. */
11652 /* Convert C1/(X*C2) into (C1/C2)/X. */
11657 {
11663 }
11666 {
11670 /* Optimize sin(x)/cos(x) as tan(x). */
11676 {
11681 }
11683 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11689 {
11693 {
11698 }
11699 }
11701 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11702 NaNs or Infinities. */
11706 {
11713 {
11718 }
11719 }
11721 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11722 NaNs or Infinities. */
11726 {
11733 {
11737 {
11741 tmp);
11742 }
11743 }
11744 }
11746 /* Optimize pow(x,c)/x as pow(x,c-1). */
11750 {
11756 {
11758 REAL_VALUE_TYPE c;
11759 tree arg;
11765 }
11766 }
11768 /* Optimize a/root(b/c) into a*root(c/b). */
11770 {
11774 {
11783 }
11784 }
11786 /* Optimize x/expN(y) into x*expN(-y). */
11788 {
11795 }
11797 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11801 {
11809 }
11810 }
11814 /* Optimize (X & (-A)) / A where A is a power of 2,
11815 to X >> log2(A) */
11819 {
11827 }
11828 }
11830 /* Fall through */
11833 /* Simplify A / (B << N) where A and B are positive and B is
11834 a power of 2, to A >> (N + log2(B)). */
11839 {
11842 {
11850 WARN_STRICT_OVERFLOW_MISC);
11856 }
11857 }
11859 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11860 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11866 /* Fall through */
11873 /* X / -1 is -X. */
11879 /* Convert -A / -B to A / B when the type is signed and overflow is
11880 undefined. */
11884 {
11887 "when distributing negation across "
11889 WARN_STRICT_OVERFLOW_MISC);
11895 }
11899 {
11902 "when distributing negation across "
11904 WARN_STRICT_OVERFLOW_MISC);
11910 }
11912 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11913 operation, EXACT_DIV_EXPR.
11915 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11916 At one time others generated faster code, it's not clear if they do
11917 after the last round to changes to the DIV code in expmed.c. */
11926 {
11930 WARN_STRICT_OVERFLOW_MISC);
11932 }
11940 /* X % -1 is zero. */
11946 /* X % -C is the same as X % C. */
11953 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11960 /* X % -Y is the same as X % Y. */
11973 {
11977 WARN_STRICT_OVERFLOW_MISC);
11979 }
11981 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11982 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11986 {
11988 /* Also optimize A % (C << N) where C is a power of 2,
11989 to A & ((C << N) - 1). */
11994 {
11995 tree mask
12000 "occur when simplifying "
12002 WARN_STRICT_OVERFLOW_MISC);
12006 }
12007 }
12018 /* Optimize -1 >> x for arithmetic right shifts. */
12022 /* ... fall through ... */
12025 shift:
12031 /* Prefer vector1 << scalar to vector1 << vector2
12032 if vector2 is uniform. */
12037 /* Since negative shift count is not well-defined,
12038 don't try to compute it in the compiler. */
12044 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
12049 {
12053 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
12054 being well defined. */
12056 {
12062 else
12064 }
12068 }
12070 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12071 into x & ((unsigned)-1 >> c) for unsigned types. */
12079 {
12082 tree lshift;
12083 tree arg00;
12086 {
12093 }
12094 }
12096 /* Rewrite an LROTATE_EXPR by a constant into an
12097 RROTATE_EXPR by a new constant. */
12099 {
12103 }
12105 /* If we have a rotate of a bit operation with the rotate count and
12106 the second operand of the bit operation both constant,
12107 permute the two operations. */
12119 /* Two consecutive rotates adding up to the some integer
12120 multiple of the precision of the type can be ignored. */
12128 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12129 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12130 if the latter can be further optimized. */
12135 {
12139 arg1);
12143 arg1);
12147 }
12175 /* Note that the operands of this must be ints
12176 and their values must be 0 or 1.
12177 ("true" is a fixed value perhaps depending on the language.) */
12178 /* If first arg is constant zero, return it. */
12182 /* If either arg is constant true, drop it. */
12186 /* Preserve sequence points. */
12189 /* If second arg is constant zero, result is zero, but first arg
12190 must be evaluated. */
12193 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12194 case will be handled here. */
12198 /* !X && X is always false. */
12202 /* X && !X is always false. */
12207 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12208 means A >= Y && A != MAX, but in this case we know that
12209 A < X <= MAX. */
12213 {
12221 }
12230 /* Note that the operands of this must be ints
12231 and their values must be 0 or true.
12232 ("true" is a fixed value perhaps depending on the language.) */
12233 /* If first arg is constant true, return it. */
12237 /* If either arg is constant zero, drop it. */
12241 /* Preserve sequence points. */
12244 /* If second arg is constant true, result is true, but we must
12245 evaluate first arg. */
12248 /* Likewise for first arg, but note this only occurs here for
12249 TRUTH_OR_EXPR. */
12253 /* !X || X is always true. */
12257 /* X || !X is always true. */
12262 /* (X && !Y) || (!X && Y) is X ^ Y */
12265 {
12282 }
12291 /* If the second arg is constant zero, drop it. */
12294 /* If the second arg is constant true, this is a logical inversion. */
12296 {
12299 }
12300 /* Identical arguments cancel to zero. */
12304 /* !X ^ X is always true. */
12309 /* X ^ !X is always true. */
12325 /* bool_var != 0 becomes bool_var. */
12330 /* bool_var == 1 becomes bool_var. */
12335 /* bool_var != 1 becomes !bool_var. */
12342 /* bool_var == 0 becomes !bool_var. */
12349 /* !exp != 0 becomes !exp */
12354 /* If this is an equality comparison of the address of two non-weak,
12355 unaliased symbols neither of which are extern (since we do not
12356 have access to attributes for externs), then we know the result. */
12369 {
12370 /* We know that we're looking at the address of two
12371 non-weak, unaliased, static _DECL nodes.
12373 It is both wasteful and incorrect to call operand_equal_p
12374 to compare the two ADDR_EXPR nodes. It is wasteful in that
12375 all we need to do is test pointer equality for the arguments
12376 to the two ADDR_EXPR nodes. It is incorrect to use
12377 operand_equal_p as that function is NOT equivalent to a
12378 C equality test. It can in fact return false for two
12379 objects which would test as equal using the C equality
12380 operator. */
12384 type);
12385 }
12387 /* Similarly for a NEGATE_EXPR. */
12391 arg1)))
12396 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12404 arg1),
12407 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12416 {
12420 val,
12424 }
12426 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12433 {
12435 code == NE_EXPR
12438 }
12440 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12445 /* If this is an EQ or NE comparison with zero and ARG0 is
12446 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12447 two operations, but the latter can be done in one less insn
12448 on machines that have only two-operand insns or on which a
12449 constant cannot be the first operand. */
12452 {
12457 {
12464 arg1);
12465 }
12468 {
12475 arg1);
12476 }
12477 }
12479 /* If this is an NE or EQ comparison of zero against the result of a
12480 signed MOD operation whose second operand is a power of 2, make
12481 the MOD operation unsigned since it is simpler and equivalent. */
12489 {
12499 }
12501 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12502 C1 is a valid shift constant, and C2 is a power of two, i.e.
12503 a single bit. */
12507 == INTEGER_CST
12510 {
12515 /* Check for a valid shift count. */
12517 {
12521 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12522 can be rewritten as (X & (C2 << C1)) != 0. */
12524 {
12529 }
12530 /* Otherwise, for signed (arithmetic) shifts,
12531 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12532 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12536 /* Otherwise, of unsigned (logical) shifts,
12537 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12538 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12539 else
12543 arg000);
12544 }
12545 }
12547 /* If we have (A & C) == C where C is a power of 2, convert this into
12548 (A & C) != 0. Similarly for NE_EXPR. */
12554 integer_zero_node));
12556 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12557 bit, then fold the expression into A < 0 or A >= 0. */
12562 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12563 Similarly for NE_EXPR. */
12567 {
12571 tree dandnotc
12574 notc);
12578 }
12580 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12581 Similarly for NE_EXPR. */
12585 {
12587 tree candnotd
12594 }
12596 /* If this is a comparison of a field, we may be able to simplify it. */
12599 /* Handle the constant case even without -O
12600 to make sure the warnings are given. */
12602 {
12606 }
12608 /* Optimize comparisons of strlen vs zero to a compare of the
12609 first character of the string vs zero. To wit,
12610 strlen(ptr) == 0 => *ptr == 0
12611 strlen(ptr) != 0 => *ptr != 0
12612 Other cases should reduce to one of these two (or a constant)
12613 due to the return value of strlen being unsigned. */
12616 {
12624 {
12629 }
12630 }
12632 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12633 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12637 {
12642 {
12644 {
12647 }
12650 }
12651 }
12653 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12659 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12664 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12671 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12679 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12680 (X & C) == 0 when C is a single bit. */
12685 {
12692 arg1));
12693 }
12695 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12696 constant C is a power of two, i.e. a single bit. */
12703 {
12707 }
12709 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12710 when is C is a power of two, i.e. a single bit. */
12717 {
12723 }
12727 {
12730 }
12732 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12740 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12743 {
12756 arg01),
12765 arg01),
12774 arg00),
12783 arg00),
12785 }
12789 {
12796 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12797 operand_equal_p guarantees no side-effects so we don't need
12798 to use omit_one_operand on Z. */
12802 arg10));
12806 arg11));
12810 arg10));
12814 arg11));
12816 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12819 {
12825 }
12826 }
12828 /* Attempt to simplify equality/inequality comparisons of complex
12829 values. Only lower the comparison if the result is known or
12830 can be simplified to a single scalar comparison. */
12835 {
12840 {
12843 }
12844 else
12845 {
12848 }
12851 {
12854 }
12855 else
12856 {
12859 }
12863 {
12865 {
12870 }
12871 else
12872 {
12877 }
12878 }
12882 {
12884 {
12889 }
12890 else
12891 {
12896 }
12897 }
12898 }
12910 /* Transform comparisons of the form X +- C CMP X. */
12917 {
12924 else
12927 /* (X - c) > X becomes false. */
12931 {
12935 "occur when assuming that (X - c) > X "
12937 WARN_STRICT_OVERFLOW_ALL);
12939 }
12941 /* Likewise (X + c) < X becomes false. */
12945 {
12949 "occur when assuming that "
12951 WARN_STRICT_OVERFLOW_ALL);
12953 }
12955 /* Convert (X - c) <= X to true. */
12960 {
12964 "occur when assuming that "
12966 WARN_STRICT_OVERFLOW_ALL);
12968 }
12970 /* Convert (X + c) >= X to true. */
12975 {
12979 "occur when assuming that "
12981 WARN_STRICT_OVERFLOW_ALL);
12983 }
12986 {
12987 /* Convert X + c > X and X - c < X to true for integers. */
12991 {
12994 "not occur when assuming that "
12996 WARN_STRICT_OVERFLOW_ALL);
12998 }
13003 {
13006 "not occur when assuming that "
13008 WARN_STRICT_OVERFLOW_ALL);
13010 }
13012 /* Convert X + c <= X and X - c >= X to false for integers. */
13016 {
13019 "not occur when assuming that "
13021 WARN_STRICT_OVERFLOW_ALL);
13023 }
13028 {
13031 "not occur when assuming that "
13033 WARN_STRICT_OVERFLOW_ALL);
13035 }
13036 }
13037 }
13039 /* Comparisons with the highest or lowest possible integer of
13040 the specified precision will have known values. */
13041 {
13047 {
13054 {
13067 /* The GE_EXPR and LT_EXPR cases above are not normally
13068 reached because of previous transformations. */
13072 }
13075 {
13082 arg1);
13088 arg0),
13089 arg1);
13092 }
13095 {
13110 }
13113 {
13120 arg1);
13126 arg0),
13127 arg1);
13130 }
13134 /* We will flip the signedness of the comparison operator
13135 associated with the mode of arg1, so the sign bit is
13136 specified by this mode. Check that arg1 is the signed
13137 max associated with this sign bit. */
13139 /* signed_type does not work on pointer types. */
13141 {
13142 /* The following case also applies to X < signed_max+1
13143 and X >= signed_max+1 because previous transformations. */
13145 {
13151 }
13152 }
13153 }
13154 }
13156 /* If we are comparing an ABS_EXPR with a constant, we can
13157 convert all the cases into explicit comparisons, but they may
13158 well not be faster than doing the ABS and one comparison.
13159 But ABS (X) <= C is a range comparison, which becomes a subtraction
13160 and a comparison, and is probably faster. */
13174 /* Convert ABS_EXPR<x> >= 0 to true. */
13181 {
13184 "when simplifying comparison of "
13186 WARN_STRICT_OVERFLOW_CONDITIONAL);
13189 arg0);
13190 }
13192 /* Convert ABS_EXPR<x> < 0 to false. */
13197 {
13200 "when simplifying comparison of "
13202 WARN_STRICT_OVERFLOW_CONDITIONAL);
13205 arg0);
13206 }
13208 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13209 and similarly for >= into !=. */
13219 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13220 otherwise Y might be >= # of bits in X's type and thus e.g.
13221 (unsigned char) (1 << Y) for Y 15 might be 0.
13222 If the cast is widening, then 1 << Y should have unsigned type,
13223 otherwise if Y is number of bits in the signed shift type minus 1,
13224 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13225 31 might be 0xffffffff80000000. */
13236 {
13242 }
13255 {
13259 }
13261 /* If the first operand is NaN, the result is constant. */
13265 {
13267 ? integer_zero_node
13270 }
13272 /* If the second operand is NaN, the result is constant. */
13276 {
13278 ? integer_zero_node
13281 }
13283 /* Simplify unordered comparison of something with itself. */
13289 && !flag_trapping_math
13293 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13294 {
13306 }
13311 /* When pedantic, a compound expression can be neither an lvalue
13312 nor an integer constant expression. */
13315 /* Don't let (0, 0) be null pointer constant. */
13329 /* An ASSERT_EXPR should never be passed to fold_binary. */
13334 {
13349 {
13355 }
13358 }
13364 {
13389 {
13402 }
13405 }
13410 }
13412 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13413 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13414 of GOTO_EXPR. */
13416 static tree
13418 {
13420 {
13427 /* ... fall through ... */
13431 }
13432 }
13434 /* Return whether the sub-tree ST contains a label which is accessible from
13435 outside the sub-tree. */
13437 static bool
13439 {
13440 return
13442 }
13444 /* Fold a ternary expression of code CODE and type TYPE with operands
13445 OP0, OP1, and OP2. Return the folded expression if folding is
13446 successful. Otherwise, return NULL_TREE. */
13448 tree
13451 {
13452 tree tem;
13459 /* If this is a commutative operation, and OP0 is a constant, move it
13460 to OP1 to reduce the number of tests below. */
13469 /* Strip any conversions that don't change the mode. This is safe
13470 for every expression, except for a comparison expression because
13471 its signedness is derived from its operands. So, in the latter
13472 case, only strip conversions that don't change the signedness.
13474 Note that this is done as an internal manipulation within the
13475 constant folder, in order to find the simplest representation of
13476 the arguments so that their form can be studied. In any cases,
13477 the appropriate type conversions should be put back in the tree
13478 that will get out of the constant folder. */
13480 {
13483 }
13486 {
13489 }
13492 {
13495 }
13498 {
13502 {
13508 }
13513 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13514 so all simple results must be passed through pedantic_non_lvalue. */
13516 {
13519 /* Only optimize constant conditions when the selected branch
13520 has the same type as the COND_EXPR. This avoids optimizing
13521 away "c ? x : throw", where the throw has a void type.
13522 Avoid throwing away that operand which contains label. */
13529 }
13531 {
13536 {
13541 {
13549 }
13553 }
13554 }
13556 /* If we have A op B ? A : C, we may be able to convert this to a
13557 simpler expression, depending on the operation and the values
13558 of B and C. Signed zeros prevent all of these transformations,
13559 for reasons given above each one.
13561 Also try swapping the arguments and inverting the conditional. */
13566 {
13570 }
13574 op2,
13577 {
13581 {
13585 }
13586 }
13588 /* If the second operand is simpler than the third, swap them
13589 since that produces better jump optimization results. */
13592 {
13594 /* See if this can be inverted. If it can't, possibly because
13595 it was a floating-point inequality comparison, don't do
13596 anything. */
13600 }
13602 /* Convert A ? 1 : 0 to simply A. */
13607 /* If we try to convert OP0 to our type, the
13608 call to fold will try to move the conversion inside
13609 a COND, which will recurse. In that case, the COND_EXPR
13610 is probably the best choice, so leave it alone. */
13614 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13615 over COND_EXPR in cases such as floating point comparisons. */
13624 arg0)));
13626 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13631 {
13632 /* sign_bit_p looks through both zero and sign extensions,
13633 but for this optimization only sign extensions are
13634 usable. */
13637 {
13640 {
13643 }
13645 }
13646 /* sign_bit_p only checks ARG1 bits within A's precision.
13647 If <sign bit of A> has wider type than A, bits outside
13648 of A's precision in <sign bit of A> need to be checked.
13649 If they are all 0, this optimization needs to be done
13650 in unsigned A's type, if they are all 1 in signed A's type,
13651 otherwise this can't be done. */
13657 {
13659 tree tem_type;
13672 {
13675 }
13677 {
13680 }
13681 else
13683 }
13686 return
13692 arg1)));
13693 }
13695 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13696 already handled above. */
13701 {
13710 }
13712 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13713 is probably obsolete because the first operand should be a
13714 truth value (that's why we have the two cases above), but let's
13715 leave it in until we can confirm this for all front-ends. */
13727 /* Disable the transformations below for vectors, since
13728 fold_binary_op_with_conditional_arg may undo them immediately,
13729 yielding an infinite loop. */
13733 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13742 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13747 {
13749 /* Only perform transformation if ARG0 is easily inverted. */
13753 ? BIT_IOR_EXPR
13756 arg1);
13757 }
13759 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13764 {
13766 /* Only perform transformation if ARG0 is easily inverted. */
13772 op2);
13773 }
13775 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13787 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13788 of fold_ternary on them. */
13798 {
13808 {
13813 {
13821 }
13823 /* Constructor elements can be subvectors. */
13826 {
13830 }
13832 /* We keep an exact subset of the constructor elements. */
13834 {
13840 {
13844 }
13852 CONSTRUCTOR_ELT
13855 }
13856 /* The bitfield references a single constructor element. */
13858 {
13863 else
13867 }
13868 }
13869 }
13871 /* A bit-field-ref that referenced the full argument can be stripped. */
13877 /* On constants we can use native encode/interpret to constant
13878 fold (nearly) all BIT_FIELD_REFs. */
13882 /* This limitation should not be necessary, we just need to
13883 round this up to mode size. */
13885 /* Need bit-shifting of the buffer to relax the following. */
13887 {
13892 /* ??? We cannot tell native_encode_expr to start at
13893 some random byte only. So limit us to a reasonable amount
13894 of work. */
13896 {
13901 {
13907 }
13908 }
13909 }
13914 /* For integers we can decompose the FMA if possible. */
13926 {
13942 {
13947 /* Make sure that the perm value is in an acceptable
13948 range. */
13957 else
13962 }
13965 {
13970 }
13975 {
13980 }
13986 {
13990 }
13995 /* Some targets are deficient and fail to expand a single
13996 argument permutation while still allowing an equivalent
13997 2-argument version. */
14001 {
14004 }
14007 {
14014 }
14018 }
14024 }
14026 /* Perform constant folding and related simplification of EXPR.
14027 The related simplifications include x*1 => x, x*0 => 0, etc.,
14028 and application of the associative law.
14029 NOP_EXPR conversions may be removed freely (as long as we
14030 are careful not to change the type of the overall expression).
14031 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
14032 but we can constant-fold them if they have constant operands. */
14034 #ifdef ENABLE_FOLD_CHECKING
14035 # define fold(x) fold_1 (x)
14037 static
14038 #endif
14039 tree
14041 {
14045 tree tem;
14048 /* Return right away if a constant. */
14052 /* CALL_EXPR-like objects with variable numbers of operands are
14053 treated specially. */
14055 {
14057 {
14060 }
14062 }
14065 {
14070 {
14088 }
14089 }
14092 {
14094 {
14101 {
14106 /* Find a matching index by means of a binary search. */
14108 {
14124 else
14126 }
14127 }
14130 }
14132 /* Return a VECTOR_CST if possible. */
14134 {
14141 tree value;
14144 {
14148 {
14151 }
14152 else
14154 }
14159 }
14167 }
14169 #ifdef ENABLE_FOLD_CHECKING
14170 #undef fold
14177 /* When --enable-checking=fold, compute a digest of expr before
14178 and after actual fold call to see if fold did not accidentally
14179 change original expr. */
14181 tree
14183 {
14184 tree ret;
14204 }
14206 void
14208 {
14219 }
14221 static void
14223 {
14225 }
14227 static void
14230 {
14236 recursive_label:
14246 {
14247 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14251 }
14258 {
14259 /* Allow these fields to be modified. */
14260 tree tmp;
14268 {
14271 }
14272 }
14283 {
14286 {
14301 }
14305 {
14318 }
14335 {
14341 }
14344 {
14346 {
14349 }
14351 }
14362 {
14365 }
14375 }
14376 }
14378 /* Helper function for outputting the checksum of a tree T. When
14379 debugging with gdb, you can "define mynext" to be "next" followed
14380 by "call debug_fold_checksum (op0)", then just trace down till the
14381 outputs differ. */
14383 DEBUG_FUNCTION void
14385 {
14400 }
14402 #endif
14404 /* Fold a unary tree expression with code CODE of type TYPE with an
14405 operand OP0. LOC is the location of the resulting expression.
14406 Return a folded expression if successful. Otherwise, return a tree
14407 expression with code CODE of type TYPE with an operand OP0. */
14409 tree
14412 {
14413 tree tem;
14414 #ifdef ENABLE_FOLD_CHECKING
14423 #endif
14429 #ifdef ENABLE_FOLD_CHECKING
14436 #endif
14438 }
14440 /* Fold a binary tree expression with code CODE of type TYPE with
14441 operands OP0 and OP1. LOC is the location of the resulting
14442 expression. Return a folded expression if successful. Otherwise,
14443 return a tree expression with code CODE of type TYPE with operands
14444 OP0 and OP1. */
14446 tree
14449 MEM_STAT_DECL)
14450 {
14451 tree tem;
14452 #ifdef ENABLE_FOLD_CHECKING
14469 #endif
14475 #ifdef ENABLE_FOLD_CHECKING
14490 #endif
14492 }
14494 /* Fold a ternary tree expression with code CODE of type TYPE with
14495 operands OP0, OP1, and OP2. Return a folded expression if
14496 successful. Otherwise, return a tree expression with code CODE of
14497 type TYPE with operands OP0, OP1, and OP2. */
14499 tree
14502 {
14503 tree tem;
14504 #ifdef ENABLE_FOLD_CHECKING
14528 #endif
14535 #ifdef ENABLE_FOLD_CHECKING
14558 #endif
14560 }
14562 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14563 arguments in ARGARRAY, and a null static chain.
14564 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14565 of type TYPE from the given operands as constructed by build_call_array. */
14567 tree
14570 {
14571 tree tem;
14572 #ifdef ENABLE_FOLD_CHECKING
14591 #endif
14595 #ifdef ENABLE_FOLD_CHECKING
14611 #endif
14613 }
14615 /* Perform constant folding and related simplification of initializer
14616 expression EXPR. These behave identically to "fold_buildN" but ignore
14617 potential run-time traps and exceptions that fold must preserve. */
14619 #define START_FOLD_INIT \
14620 int saved_signaling_nans = flag_signaling_nans;\
14621 int saved_trapping_math = flag_trapping_math;\
14622 int saved_rounding_math = flag_rounding_math;\
14623 int saved_trapv = flag_trapv;\
14624 int saved_folding_initializer = folding_initializer;\
14625 flag_signaling_nans = 0;\
14626 flag_trapping_math = 0;\
14627 flag_rounding_math = 0;\
14628 flag_trapv = 0;\
14629 folding_initializer = 1;
14631 #define END_FOLD_INIT \
14632 flag_signaling_nans = saved_signaling_nans;\
14633 flag_trapping_math = saved_trapping_math;\
14634 flag_rounding_math = saved_rounding_math;\
14635 flag_trapv = saved_trapv;\
14636 folding_initializer = saved_folding_initializer;
14638 tree
14641 {
14642 tree result;
14643 START_FOLD_INIT;
14647 END_FOLD_INIT;
14649 }
14651 tree
14654 {
14655 tree result;
14656 START_FOLD_INIT;
14660 END_FOLD_INIT;
14662 }
14664 tree
14667 {
14668 tree result;
14669 START_FOLD_INIT;
14673 END_FOLD_INIT;
14675 }
14677 #undef START_FOLD_INIT
14678 #undef END_FOLD_INIT
14680 /* Determine if first argument is a multiple of second argument. Return 0 if
14681 it is not, or we cannot easily determined it to be.
14683 An example of the sort of thing we care about (at this point; this routine
14684 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14685 fold cases do now) is discovering that
14687 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14689 is a multiple of
14691 SAVE_EXPR (J * 8)
14693 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14695 This code also handles discovering that
14697 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14699 is a multiple of 8 so we don't have to worry about dealing with a
14700 possible remainder.
14702 Note that we *look* inside a SAVE_EXPR only to determine how it was
14703 calculated; it is not safe for fold to do much of anything else with the
14704 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14705 at run time. For example, the latter example above *cannot* be implemented
14706 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14707 evaluation time of the original SAVE_EXPR is not necessarily the same at
14708 the time the new expression is evaluated. The only optimization of this
14709 sort that would be valid is changing
14711 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14713 divided by 8 to
14715 SAVE_EXPR (I) * SAVE_EXPR (J)
14717 (where the same SAVE_EXPR (J) is used in the original and the
14718 transformed version). */
14720 int
14722 {
14730 {
14732 /* Bitwise and provides a power of two multiple. If the mask is
14733 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14736 /* FALLTHRU */
14749 {
14753 /* const_binop may not detect overflow correctly,
14754 so check for it explicitly here. */
14758 size_one_node,
14759 op1)))
14762 }
14766 /* Can't handle conversions from non-integral or wider integral type. */
14772 /* .. fall through ... */
14789 SIGNED);
14793 }
14794 }
14796 /* Return true if CODE or TYPE is known to be non-negative. */
14798 static bool
14800 {
14803 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14804 have a signed:1 type (where the value is -1 and 0). */
14807 }
14809 /* Return true if (CODE OP0) is known to be non-negative. If the return
14810 value is based on the assumption that signed overflow is undefined,
14811 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14812 *STRICT_OVERFLOW_P. */
14814 bool
14817 {
14822 {
14824 /* We can't return 1 if flag_wrapv is set because
14825 ABS_EXPR<INT_MIN> = INT_MIN. */
14829 {
14832 }
14839 strict_overflow_p);
14842 {
14847 {
14850 strict_overflow_p);
14852 {
14856 strict_overflow_p);
14857 }
14858 }
14860 {
14863 strict_overflow_p);
14867 }
14868 }
14873 }
14875 /* We don't know sign of `t', so be conservative and return false. */
14877 }
14879 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14880 value is based on the assumption that signed overflow is undefined,
14881 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14882 *STRICT_OVERFLOW_P. */
14884 bool
14887 {
14892 {
14897 strict_overflow_p)
14899 strict_overflow_p));
14901 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14902 both unsigned and at least 2 bits shorter than the result. */
14906 {
14911 {
14915 }
14916 }
14921 {
14922 /* x * x is always non-negative for floating point x
14923 or without overflow. */
14927 {
14931 }
14932 }
14934 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14935 both unsigned and their total bits is shorter than the result. */
14939 {
14958 {
14968 }
14969 }
14975 strict_overflow_p)
14977 strict_overflow_p));
14988 strict_overflow_p)
14990 strict_overflow_p));
14997 strict_overflow_p);
15000 }
15002 /* We don't know sign of `t', so be conservative and return false. */
15004 }
15006 /* Return true if T is known to be non-negative. If the return
15007 value is based on the assumption that signed overflow is undefined,
15008 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15009 *STRICT_OVERFLOW_P. */
15011 bool
15013 {
15018 {
15030 strict_overflow_p)
15032 strict_overflow_p));
15036 }
15037 /* We don't know sign of `t', so be conservative and return false. */
15039 }
15041 /* Return true if T is known to be non-negative. If the return
15042 value is based on the assumption that signed overflow is undefined,
15043 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15044 *STRICT_OVERFLOW_P. */
15046 bool
15049 {
15052 {
15072 /* Always true. */
15076 /* sqrt(-0.0) is -0.0. */
15080 strict_overflow_p);
15117 /* True if the 1st argument is nonnegative. */
15119 strict_overflow_p);
15122 /* True if the 1st OR 2nd arguments are nonnegative. */
15124 strict_overflow_p)
15126 strict_overflow_p)));
15129 /* True if the 1st AND 2nd arguments are nonnegative. */
15131 strict_overflow_p)
15133 strict_overflow_p)));
15136 /* True if the 2nd argument is nonnegative. */
15138 strict_overflow_p);
15141 /* True if the 1st argument is nonnegative or the second
15142 argument is an even integer. */
15147 strict_overflow_p);
15150 /* True if the 1st argument is nonnegative or the second
15151 argument is an even integer valued real. */
15153 {
15154 REAL_VALUE_TYPE c;
15155 HOST_WIDE_INT n;
15160 {
15161 REAL_VALUE_TYPE cint;
15165 }
15166 }
15168 strict_overflow_p);
15172 }
15174 type);
15175 }
15177 /* Return true if T is known to be non-negative. If the return
15178 value is based on the assumption that signed overflow is undefined,
15179 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15180 *STRICT_OVERFLOW_P. */
15182 static bool
15184 {
15190 {
15192 {
15196 /* If the initializer is non-void, then it's a normal expression
15197 that will be assigned to the slot. */
15201 /* Otherwise, the initializer sets the slot in some way. One common
15202 way is an assignment statement at the end of the initializer. */
15204 {
15212 else
15214 }
15218 strict_overflow_p);
15221 }
15224 {
15230 arg0,
15231 arg1,
15232 strict_overflow_p);
15233 }
15237 strict_overflow_p);
15240 strict_overflow_p);
15243 strict_overflow_p);
15248 }
15250 /* We don't know sign of `t', so be conservative and return false. */
15252 }
15254 /* Return true if T is known to be non-negative. If the return
15255 value is based on the assumption that signed overflow is undefined,
15256 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15257 *STRICT_OVERFLOW_P. */
15259 bool
15261 {
15268 {
15275 strict_overflow_p);
15281 strict_overflow_p);
15290 }
15293 {
15301 strict_overflow_p);
15306 strict_overflow_p);
15319 }
15320 }
15322 /* Return true if `t' is known to be non-negative. Handle warnings
15323 about undefined signed overflow. */
15325 bool
15327 {
15334 "determining that expression is always "
15336 WARN_STRICT_OVERFLOW_MISC);
15338 }
15341 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15342 For floating point we further ensure that T is not denormal.
15343 Similar logic is present in nonzero_address in rtlanal.h.
15345 If the return value is based on the assumption that signed overflow
15346 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15347 change *STRICT_OVERFLOW_P. */
15349 bool
15352 {
15354 {
15357 strict_overflow_p);
15360 {
15366 strict_overflow_p));
15367 }
15372 strict_overflow_p);
15376 }
15379 }
15381 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15382 For floating point we further ensure that T is not denormal.
15383 Similar logic is present in nonzero_address in rtlanal.h.
15385 If the return value is based on the assumption that signed overflow
15386 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15387 change *STRICT_OVERFLOW_P. */
15389 bool
15391 tree type,
15392 tree op0,
15394 {
15397 {
15401 {
15402 /* With the presence of negative values it is hard
15403 to say something. */
15410 /* One of operands must be positive and the other non-negative. */
15411 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15412 overflows, on a twos-complement machine the sum of two
15413 nonnegative numbers can never be zero. */
15415 strict_overflow_p)
15417 strict_overflow_p));
15418 }
15423 {
15425 strict_overflow_p)
15427 strict_overflow_p))
15428 {
15431 }
15432 }
15441 {
15444 }
15451 {
15455 /* When both operands are nonzero, then MAX must be too. */
15457 strict_overflow_p))
15460 /* MAX where operand 0 is positive is positive. */
15462 strict_overflow_p);
15463 }
15464 /* MAX where operand 1 is positive is positive. */
15469 {
15473 }
15478 strict_overflow_p)
15480 strict_overflow_p));
15484 }
15487 }
15489 /* Return true when T is an address and is known to be nonzero.
15490 For floating point we further ensure that T is not denormal.
15491 Similar logic is present in nonzero_address in rtlanal.h.
15493 If the return value is based on the assumption that signed overflow
15494 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15495 change *STRICT_OVERFLOW_P. */
15497 bool
15499 {
15502 {
15507 {
15516 /* For objects in symbol table check if we know they are non-zero.
15517 Don't do anything for variables and functions before symtab is built;
15518 it is quite possible that they will be declared weak later. */
15520 {
15526 else
15528 }
15530 /* Function local objects are never NULL. */
15537 /* Constants are never weak. */
15542 }
15550 {
15554 }
15559 }
15561 }
15563 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15564 attempt to fold the expression to a constant without modifying TYPE,
15565 OP0 or OP1.
15567 If the expression could be simplified to a constant, then return
15568 the constant. If the expression would not be simplified to a
15569 constant, then return NULL_TREE. */
15571 tree
15573 {
15576 }
15578 /* Given the components of a unary expression CODE, TYPE and OP0,
15579 attempt to fold the expression to a constant without modifying
15580 TYPE or OP0.
15582 If the expression could be simplified to a constant, then return
15583 the constant. If the expression would not be simplified to a
15584 constant, then return NULL_TREE. */
15586 tree
15588 {
15591 }
15593 /* If EXP represents referencing an element in a constant string
15594 (either via pointer arithmetic or array indexing), return the
15595 tree representing the value accessed, otherwise return NULL. */
15597 tree
15599 {
15603 {
15605 tree index;
15606 tree string;
15611 else
15612 {
15616 /* Optimize the special-case of a zero lower bound.
15618 We convert the low_bound to sizetype to avoid some problems
15619 with constant folding. (E.g. suppose the lower bound is 1,
15620 and its mode is QI. Without the conversion,l (ARRAY
15621 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15622 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15628 }
15641 }
15643 }
15645 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15646 an integer constant, real, or fixed-point constant.
15648 TYPE is the type of the result. */
15650 static tree
15652 {
15656 {
15658 {
15665 }
15672 {
15673 FIXED_VALUE_TYPE f;
15678 /* Propagate overflow flags. */
15682 }
15686 }
15689 }
15691 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15692 an integer constant or real constant.
15694 TYPE is the type of the result. */
15696 tree
15698 {
15702 {
15704 {
15705 /* If the value is unsigned or non-negative, then the absolute value
15706 is the same as the ordinary value. */
15710 /* If the value is negative, then the absolute value is
15711 its negation. */
15712 else
15713 {
15718 }
15719 }
15725 else
15731 }
15734 }
15736 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15737 constant. TYPE is the type of the result. */
15739 static tree
15741 {
15745 }
15747 /* Given CODE, a relational operator, the target type, TYPE and two
15748 constant operands OP0 and OP1, return the result of the
15749 relational operation. If the result is not a compile time
15750 constant, then return NULL_TREE. */
15752 static tree
15754 {
15757 /* From here on, the only cases we handle are when the result is
15758 known to be a constant. */
15761 {
15765 /* Handle the cases where either operand is a NaN. */
15767 {
15769 {
15797 }
15800 }
15803 }
15806 {
15810 }
15812 /* Handle equality/inequality of complex constants. */
15814 {
15825 else
15827 }
15830 {
15837 {
15849 }
15852 }
15854 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15856 To compute GT, swap the arguments and do LT.
15857 To compute GE, do LT and invert the result.
15858 To compute LE, swap the arguments, do LT and invert the result.
15859 To compute NE, do EQ and invert the result.
15861 Therefore, the code below must handle only EQ and LT. */
15864 {
15869 }
15871 /* Note that it is safe to invert for real values here because we
15872 have already handled the one case that it matters. */
15876 {
15879 }
15881 /* Compute a result for LT or EQ if args permit;
15882 Otherwise return T. */
15884 {
15887 else
15889 }
15890 else
15896 }
15898 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15899 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15900 itself. */
15902 tree
15904 {
15905 /* If the expression does not have side effects then we don't have to wrap
15906 it with a cleanup point expression. */
15910 /* If the expression is a return, check to see if the expression inside the
15911 return has no side effects or the right hand side of the modify expression
15912 inside the return. If either don't have side effects set we don't need to
15913 wrap the expression in a cleanup point expression. Note we don't check the
15914 left hand side of the modify because it should always be a return decl. */
15916 {
15923 }
15926 }
15928 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15929 of an indirection through OP0, or NULL_TREE if no simplification is
15930 possible. */
15932 tree
15934 {
15936 tree subtype;
15944 {
15947 /* *&CONST_DECL -> to the value of the const decl. */
15950 /* *&p => p; make sure to handle *&"str"[cst] here. */
15952 {
15956 else
15958 }
15959 /* *(foo *)&fooarray => fooarray[0] */
15962 && (!in_gimple_form
15964 {
15974 }
15975 /* *(foo *)&complexfoo => __real__ complexfoo */
15979 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15982 {
15986 }
15987 }
15991 {
15997 {
15998 tree op00type;
16002 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
16005 {
16017 }
16018 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
16021 {
16025 }
16026 /* ((foo *)&fooarray)[1] => fooarray[1] */
16029 {
16039 }
16040 }
16041 }
16043 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
16046 && (!in_gimple_form
16048 {
16049 tree type_domain;
16059 NULL_TREE);
16060 }
16063 }
16065 /* Builds an expression for an indirection through T, simplifying some
16066 cases. */
16068 tree
16070 {
16078 }
16080 /* Given an INDIRECT_REF T, return either T or a simplified version. */
16082 tree
16084 {
16089 else
16091 }
16093 /* Strip non-trapping, non-side-effecting tree nodes from an expression
16094 whose result is ignored. The type of the returned tree need not be
16095 the same as the original expression. */
16097 tree
16099 {
16105 {
16116 else
16122 {
16138 }
16143 }
16144 }
16146 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
16148 tree
16150 {
16156 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16157 have to do anything. Only do this when we are not given a const,
16158 because in that case, this check is more expensive than just
16159 doing it. */
16161 {
16166 }
16168 /* If divisor is a power of two, simplify this to bit manipulation. */
16170 {
16172 {
16186 }
16187 else
16188 {
16189 tree t;
16195 }
16196 }
16197 else
16198 {
16203 }
16206 }
16208 /* Likewise, but round down. */
16210 tree
16212 {
16219 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16220 have to do anything. Only do this when we are not given a const,
16221 because in that case, this check is more expensive than just
16222 doing it. */
16224 {
16229 }
16231 /* If divisor is a power of two, simplify this to bit manipulation. */
16233 {
16234 tree t;
16238 }
16239 else
16240 {
16245 }
16248 }
16250 /* Returns the pointer to the base of the object addressed by EXP and
16251 extracts the information about the offset of the access, storing it
16252 to PBITPOS and POFFSET. */
16254 static tree
16257 {
16258 tree core;
16259 machine_mode mode;
16261 HOST_WIDE_INT bitsize;
16265 {
16270 }
16271 else
16272 {
16276 }
16279 }
16281 /* Returns true if addresses of E1 and E2 differ by a constant, false
16282 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16284 bool
16286 {
16300 {
16310 }
16312 {
16313 /* If only one of the offsets is non-constant, the difference cannot
16314 be a constant. */
16316 }
16317 else
16322 }
16324 /* Simplify the floating point expression EXP when the sign of the
16325 result is not significant. Return NULL_TREE if no simplification
16326 is possible. */
16328 tree
16330 {
16335 {
16371 {
16374 {
16376 /* Strip copysign function call, return the 1st argument. */
16382 /* Strip sign ops from the argument of "odd" math functions. */
16384 {
16388 }
16390 }
16391 }
16396 }
16398 }