| blob | 9183430205becea5fe90c45a115db000951cadf6 |
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 *,
160 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
161 Otherwise, return LOC. */
163 static location_t
165 {
168 }
170 /* Similar to protected_set_expr_location, but never modify x in place,
171 if location can and needs to be set, unshare it. */
175 {
181 {
184 }
186 }
187 \f
188 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
189 division and returns the quotient. Otherwise returns
190 NULL_TREE. */
192 tree
194 {
195 widest_int quo;
202 }
203 \f
204 /* This is nonzero if we should defer warnings about undefined
205 overflow. This facility exists because these warnings are a
206 special case. The code to estimate loop iterations does not want
207 to issue any warnings, since it works with expressions which do not
208 occur in user code. Various bits of cleanup code call fold(), but
209 only use the result if it has certain characteristics (e.g., is a
210 constant); that code only wants to issue a warning if the result is
211 used. */
215 /* If a warning about undefined overflow is deferred, this is the
216 warning. Note that this may cause us to turn two warnings into
217 one, but that is fine since it is sufficient to only give one
218 warning per expression. */
222 /* If a warning about undefined overflow is deferred, this is the
223 level at which the warning should be emitted. */
227 /* Start deferring overflow warnings. We could use a stack here to
228 permit nested calls, but at present it is not necessary. */
230 void
232 {
234 }
236 /* Stop deferring overflow warnings. If there is a pending warning,
237 and ISSUE is true, then issue the warning if appropriate. STMT is
238 the statement with which the warning should be associated (used for
239 location information); STMT may be NULL. CODE is the level of the
240 warning--a warn_strict_overflow_code value. This function will use
241 the smaller of CODE and the deferred code when deciding whether to
242 issue the warning. CODE may be zero to mean to always use the
243 deferred code. */
245 void
247 {
249 location_t locus;
254 {
260 }
271 /* Use the smallest code level when deciding to issue the
272 warning. */
281 else
284 }
286 /* Stop deferring overflow warnings, ignoring any deferred
287 warnings. */
289 void
291 {
293 }
295 /* Whether we are deferring overflow warnings. */
297 bool
299 {
301 }
303 /* This is called when we fold something based on the fact that signed
304 overflow is undefined. */
306 static void
308 {
310 {
313 {
316 }
317 }
320 }
321 \f
322 /* Return true if the built-in mathematical function specified by CODE
323 is odd, i.e. -f(x) == f(-x). */
325 static bool
327 {
329 {
363 }
365 }
367 /* Check whether we may negate an integer constant T without causing
368 overflow. */
370 bool
372 {
373 tree type;
382 }
384 /* Determine whether an expression T can be cheaply negated using
385 the function negate_expr without introducing undefined overflow. */
387 static bool
389 {
390 tree type;
399 {
404 /* Check that -CST will not overflow type. */
417 /* We want to canonicalize to positive real constants. Pretend
418 that only negative ones can be easily negated. */
426 {
437 }
450 /* -(A + B) -> (-B) - A. */
455 /* -(A + B) -> (-A) - B. */
459 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
469 /* Fall through. */
480 /* In general we can't negate A / B, because if A is INT_MIN and
481 B is 1, we may turn this into INT_MIN / -1 which is undefined
482 and actually traps on some architectures. But if overflow is
483 undefined, we can negate, because - (INT_MIN / 1) is an
484 overflow. */
486 {
489 /* If overflow is undefined then we have to be careful because
490 we ask whether it's ok to associate the negate with the
491 division which is not ok for example for
492 -((a - b) / c) where (-(a - b)) / c may invoke undefined
493 overflow because of negating INT_MIN. So do not use
494 negate_expr_p here but open-code the two important cases. */
499 }
505 /* Negate -((double)float) as (double)(-float). */
507 {
511 }
515 /* Negate -f(x) as f(-x). */
521 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
523 {
527 }
532 }
534 }
536 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
537 simplification is possible.
538 If negate_expr_p would return true for T, NULL_TREE will never be
539 returned. */
541 static tree
543 {
545 tree tem;
548 {
549 /* Convert - (~A) to A + 1. */
567 /* Two's complement FP formats, such as c4x, may overflow. */
577 {
586 }
590 {
595 {
599 }
602 }
625 {
626 /* -(A + B) -> (-B) - A. */
630 {
634 }
636 /* -(A + B) -> (-A) - B. */
638 {
642 }
643 }
647 /* - (A - B) -> B - A */
659 /* Fall through. */
663 {
672 }
678 /* In general we can't negate A / B, because if A is INT_MIN and
679 B is 1, we may turn this into INT_MIN / -1 which is undefined
680 and actually traps on some architectures. But if overflow is
681 undefined, we can negate, because - (INT_MIN / 1) is an
682 overflow. */
684 {
689 {
696 }
697 /* If overflow is undefined then we have to be careful because
698 we ask whether it's ok to associate the negate with the
699 division which is not ok for example for
700 -((a - b) / c) where (-(a - b)) / c may invoke undefined
701 overflow because of negating INT_MIN. So do not use
702 negate_expr_p here but open-code the two important cases. */
711 }
715 /* Convert -((double)float) into (double)(-float). */
717 {
721 }
725 /* Negate -f(x) as f(-x). */
728 {
734 }
738 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
740 {
743 {
750 }
751 }
756 }
759 }
761 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
762 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
763 return NULL_TREE. */
765 static tree
767 {
769 location_t loc;
782 }
783 \f
784 /* Split a tree IN into a constant, literal and variable parts that could be
785 combined with CODE to make IN. "constant" means an expression with
786 TREE_CONSTANT but that isn't an actual constant. CODE must be a
787 commutative arithmetic operation. Store the constant part into *CONP,
788 the literal in *LITP and return the variable part. If a part isn't
789 present, set it to null. If the tree does not decompose in this way,
790 return the entire tree as the variable part and the other parts as null.
792 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
793 case, we negate an operand that was subtracted. Except if it is a
794 literal for which we use *MINUS_LITP instead.
796 If NEGATE_P is true, we are negating all of IN, again except a literal
797 for which we use *MINUS_LITP instead.
799 If IN is itself a literal or constant, return it as appropriate.
801 Note that we do not guarantee that any of the three values will be the
802 same type as IN, but they will have the same signedness and mode. */
804 static tree
807 {
814 /* Strip any conversions that don't change the machine mode or signedness. */
823 /* We can associate addition and subtraction together (even
824 though the C standard doesn't say so) for integers because
825 the value is not affected. For reals, the value might be
826 affected, so we can't. */
829 {
835 /* First see if either of the operands is a literal, then a constant. */
848 /* If we haven't dealt with either operand, this is not a case we can
849 decompose. Otherwise, VAR is either of the ones remaining, if any. */
854 else
857 /* Now do any needed negations. */
864 }
867 {
868 /* -X - 1 is folded to ~X, undo that here. */
871 }
874 else
878 {
885 }
888 }
890 /* Re-associate trees split by the above function. T1 and T2 are
891 either expressions to associate or null. Return the new
892 expression, if any. LOC is the location of the new expression. If
893 we build an operation, do it in TYPE and with CODE. */
895 static tree
897 {
903 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
904 try to fold this since we will have infinite recursion. But do
905 deal with any NEGATE_EXPRs. */
908 {
910 {
923 }
925 {
928 }
932 }
936 }
937 \f
938 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
939 for use in int_const_binop, size_binop and size_diffop. */
941 static bool
943 {
950 {
959 }
964 }
967 /* Combine two integer constants ARG1 and ARG2 under operation CODE
968 to produce a new constant. Return NULL_TREE if we don't know how
969 to evaluate CODE at compile-time. */
971 static tree
974 {
975 wide_int res;
976 tree t;
985 {
1001 {
1005 else
1007 }
1010 /* It's unclear from the C standard whether shifts can overflow.
1011 The following code ignores overflow; perhaps a C standard
1012 interpretation ruling is needed. */
1014 else
1021 {
1025 else
1027 }
1031 else
1110 }
1118 }
1120 tree
1122 {
1124 }
1126 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1127 constant. We assume ARG1 and ARG2 have the same data type, or at least
1128 are the same kind of constant and the same machine mode. Return zero if
1129 combining the constants is not allowed in the current operating mode. */
1131 static tree
1133 {
1134 /* Sanity check for the recursive cases. */
1145 {
1146 machine_mode mode;
1147 REAL_VALUE_TYPE d1;
1148 REAL_VALUE_TYPE d2;
1149 REAL_VALUE_TYPE value;
1150 REAL_VALUE_TYPE result;
1154 /* The following codes are handled by real_arithmetic. */
1156 {
1167 }
1175 /* Don't perform operation if we honor signaling NaNs and
1176 either operand is a NaN. */
1181 /* Don't perform operation if it would raise a division
1182 by zero exception. */
1188 /* If either operand is a NaN, just return it. Otherwise, set up
1189 for floating-point trap; we return an overflow. */
1198 /* Don't constant fold this floating point operation if
1199 the result has overflowed and flag_trapping_math. */
1207 /* Don't constant fold this floating point operation if the
1208 result may dependent upon the run-time rounding mode and
1209 flag_rounding_math is set, or if GCC's software emulation
1210 is unable to accurately represent the result. */
1220 }
1223 {
1224 FIXED_VALUE_TYPE f1;
1225 FIXED_VALUE_TYPE f2;
1226 FIXED_VALUE_TYPE result;
1231 /* The following codes are handled by fixed_arithmetic. */
1233 {
1243 {
1248 }
1253 }
1260 /* Propagate overflow flags. */
1264 }
1267 {
1276 {
1287 mpc_mul);
1301 mpc_div);
1302 /* Fallthru ... */
1308 {
1309 /* Keep this algorithm in sync with
1310 tree-complex.c:expand_complex_div_straight().
1312 Expand complex division to scalars, straightforward algorithm.
1313 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1314 t = br*br + bi*bi
1315 */
1316 tree magsquared
1320 tree t1
1324 tree t2
1331 }
1332 else
1333 {
1334 /* Keep this algorithm in sync with
1335 tree-complex.c:expand_complex_div_wide().
1337 Expand complex division to scalars, modified algorithm to minimize
1338 overflow with wide input ranges. */
1344 {
1345 /* In the TRUE branch, we compute
1346 ratio = br/bi;
1347 div = (br * ratio) + bi;
1348 tr = (ar * ratio) + ai;
1349 ti = (ai * ratio) - ar;
1350 tr = tr / div;
1351 ti = ti / div; */
1362 }
1363 else
1364 {
1365 /* In the FALSE branch, we compute
1366 ratio = d/c;
1367 divisor = (d * ratio) + c;
1368 tr = (b * ratio) + a;
1369 ti = b - (a * ratio);
1370 tr = tr / div;
1371 ti = ti / div; */
1383 }
1384 }
1389 }
1393 }
1397 {
1403 {
1409 /* It is possible that const_binop cannot handle the given
1410 code and return NULL_TREE */
1413 }
1416 }
1418 /* Shifts allow a scalar offset for a vector. */
1421 {
1427 {
1432 /* It is possible that const_binop cannot handle the given
1433 code and return NULL_TREE. */
1436 }
1439 }
1441 }
1443 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1444 indicates which particular sizetype to create. */
1446 tree
1448 {
1450 }
1451 \f
1452 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1453 is a tree code. The type of the result is taken from the operands.
1454 Both must be equivalent integer types, ala int_binop_types_match_p.
1455 If the operands are constant, so is the result. */
1457 tree
1459 {
1468 /* Handle the special case of two integer constants faster. */
1470 {
1471 /* And some specific cases even faster than that. */
1473 {
1478 }
1480 {
1483 }
1485 {
1488 }
1490 /* Handle general case of two integer constants. For sizetype
1491 constant calculations we always want to know about overflow,
1492 even in the unsigned case. */
1494 }
1497 }
1499 /* Given two values, either both of sizetype or both of bitsizetype,
1500 compute the difference between the two values. Return the value
1501 in signed type corresponding to the type of the operands. */
1503 tree
1505 {
1507 tree ctype;
1512 /* If the type is already signed, just do the simple thing. */
1520 else
1523 /* If either operand is not a constant, do the conversions to the signed
1524 type and subtract. The hardware will do the right thing with any
1525 overflow in the subtraction. */
1531 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1532 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1533 overflow) and negate (which can't either). Special-case a result
1534 of zero while we're here. */
1540 else
1544 MINUS_EXPR,
1546 }
1547 \f
1548 /* A subroutine of fold_convert_const handling conversions of an
1549 INTEGER_CST to another integer type. */
1551 static tree
1553 {
1554 /* Given an integer constant, make new constant with new type,
1555 appropriately sign-extended or truncated. Use widest_int
1556 so that any extension is done according ARG1's type. */
1560 }
1562 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1563 to an integer type. */
1565 static tree
1567 {
1569 tree t;
1571 /* The following code implements the floating point to integer
1572 conversion rules required by the Java Language Specification,
1573 that IEEE NaNs are mapped to zero and values that overflow
1574 the target precision saturate, i.e. values greater than
1575 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1576 are mapped to INT_MIN. These semantics are allowed by the
1577 C and C++ standards that simply state that the behavior of
1578 FP-to-integer conversion is unspecified upon overflow. */
1580 wide_int val;
1581 REAL_VALUE_TYPE r;
1585 {
1592 }
1594 /* If R is NaN, return zero and show we have an overflow. */
1596 {
1599 }
1601 /* See if R is less than the lower bound or greater than the
1602 upper bound. */
1605 {
1609 {
1612 }
1613 }
1616 {
1619 {
1622 {
1625 }
1626 }
1627 }
1634 }
1636 /* A subroutine of fold_convert_const handling conversions of a
1637 FIXED_CST to an integer type. */
1639 static tree
1641 {
1642 tree t;
1646 /* Right shift FIXED_CST to temp by fbit. */
1650 {
1652 HOST_BITS_PER_DOUBLE_INT,
1655 /* Left shift temp to temp_trunc by fbit. */
1657 HOST_BITS_PER_DOUBLE_INT,
1659 }
1660 else
1661 {
1664 }
1666 /* If FIXED_CST is negative, we need to round the value toward 0.
1667 By checking if the fractional bits are not zero to add 1 to temp. */
1673 /* Given a fixed-point constant, make new constant with new type,
1674 appropriately sign-extended or truncated. */
1682 }
1684 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1685 to another floating point type. */
1687 static tree
1689 {
1690 REAL_VALUE_TYPE value;
1691 tree t;
1696 /* If converting an infinity or NAN to a representation that doesn't
1697 have one, set the overflow bit so that we can produce some kind of
1698 error message at the appropriate point if necessary. It's not the
1699 most user-friendly message, but it's better than nothing. */
1706 /* Regular overflow, conversion produced an infinity in a mode that
1707 can't represent them. */
1712 else
1715 }
1717 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1718 to a floating point type. */
1720 static tree
1722 {
1723 REAL_VALUE_TYPE value;
1724 tree t;
1731 }
1733 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1734 to another fixed-point type. */
1736 static tree
1738 {
1739 FIXED_VALUE_TYPE value;
1740 tree t;
1747 /* Propagate overflow flags. */
1751 }
1753 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
1754 to a fixed-point type. */
1756 static tree
1758 {
1759 FIXED_VALUE_TYPE value;
1760 tree t;
1762 double_int di;
1769 else
1777 /* Propagate overflow flags. */
1781 }
1783 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1784 to a fixed-point type. */
1786 static tree
1788 {
1789 FIXED_VALUE_TYPE value;
1790 tree t;
1798 /* Propagate overflow flags. */
1802 }
1804 /* Attempt to fold type conversion operation CODE of expression ARG1 to
1805 type TYPE. If no simplification can be done return NULL_TREE. */
1807 static tree
1809 {
1815 {
1822 }
1824 {
1831 }
1833 {
1840 }
1842 }
1844 /* Construct a vector of zero elements of vector type TYPE. */
1846 static tree
1848 {
1849 tree t;
1853 }
1855 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
1857 bool
1859 {
1874 {
1893 }
1894 }
1896 /* Convert expression ARG to type TYPE. Used by the middle-end for
1897 simple conversions in preference to calling the front-end's convert. */
1899 tree
1901 {
1903 tree tem;
1914 {
1917 /* Handle conversions between pointers to different address spaces. */
1922 /* fall through */
1927 {
1931 }
1945 {
1949 }
1951 {
1955 }
1957 {
1961 }
1964 {
1982 }
1987 {
1991 }
1994 {
2008 }
2012 {
2021 integer_zero_node));
2023 {
2027 {
2033 }
2041 }
2045 }
2063 }
2064 fold_convert_exit:
2067 }
2068 \f
2069 /* Return false if expr can be assumed not to be an lvalue, true
2070 otherwise. */
2072 static bool
2074 {
2075 /* We only need to wrap lvalue tree codes. */
2077 {
2108 /* Assume the worst for front-end tree codes. */
2112 }
2115 }
2117 /* Return an expr equal to X but certainly not valid as an lvalue. */
2119 tree
2121 {
2122 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2123 us. */
2130 }
2132 /* When pedantic, return an expr equal to X but certainly not valid as a
2133 pedantic lvalue. Otherwise, return X. */
2135 static tree
2137 {
2139 }
2140 \f
2141 /* Given a tree comparison code, return the code that is the logical inverse.
2142 It is generally not safe to do this for floating-point comparisons, except
2143 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2144 ERROR_MARK in this case. */
2146 enum tree_code
2148 {
2154 {
2185 }
2186 }
2188 /* Similar, but return the comparison that results if the operands are
2189 swapped. This is safe for floating-point. */
2191 enum tree_code
2193 {
2195 {
2221 }
2222 }
2225 /* Convert a comparison tree code from an enum tree_code representation
2226 into a compcode bit-based encoding. This function is the inverse of
2227 compcode_to_comparison. */
2229 static enum comparison_code
2231 {
2233 {
2264 }
2265 }
2267 /* Convert a compcode bit-based encoding of a comparison operator back
2268 to GCC's enum tree_code representation. This function is the
2269 inverse of comparison_to_compcode. */
2271 static enum tree_code
2273 {
2275 {
2306 }
2307 }
2309 /* Return a tree for the comparison which is the combination of
2310 doing the AND or OR (depending on CODE) of the two operations LCODE
2311 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2312 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2313 if this makes the transformation invalid. */
2315 tree
2320 {
2327 {
2338 }
2341 {
2342 /* Eliminate unordered comparisons, as well as LTGT and ORD
2343 which are not used unless the mode has NaNs. */
2349 }
2351 {
2352 /* Check that the original operation and the optimized ones will trap
2353 under the same condition. */
2364 /* In a short-circuited boolean expression the LHS might be
2365 such that the RHS, if evaluated, will never trap. For
2366 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2367 if neither x nor y is NaN. (This is a mixed blessing: for
2368 example, the expression above will never trap, hence
2369 optimizing it to x < y would be invalid). */
2374 /* If the comparison was short-circuited, and only the RHS
2375 trapped, we may now generate a spurious trap. */
2380 /* If we changed the conditions that cause a trap, we lose. */
2383 }
2389 else
2390 {
2395 }
2396 }
2397 \f
2398 /* Return nonzero if two operands (typically of the same tree node)
2399 are necessarily equal. If either argument has side-effects this
2400 function returns zero. FLAGS modifies behavior as follows:
2402 If OEP_ONLY_CONST is set, only return nonzero for constants.
2403 This function tests whether the operands are indistinguishable;
2404 it does not test whether they are equal using C's == operation.
2405 The distinction is important for IEEE floating point, because
2406 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2407 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2409 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2410 even though it may hold multiple values during a function.
2411 This is because a GCC tree node guarantees that nothing else is
2412 executed between the evaluation of its "operands" (which may often
2413 be evaluated in arbitrary order). Hence if the operands themselves
2414 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2415 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2416 unset means assuming isochronic (or instantaneous) tree equivalence.
2417 Unless comparing arbitrary expression trees, such as from different
2418 statements, this flag can usually be left unset.
2420 If OEP_PURE_SAME is set, then pure functions with identical arguments
2421 are considered the same. It is used when the caller has other ways
2422 to ensure that global memory is unchanged in between. */
2424 int
2426 {
2427 /* If either is ERROR_MARK, they aren't equal. */
2433 /* Similar, if either does not have a type (like a released SSA name),
2434 they aren't equal. */
2438 /* Check equality of integer constants before bailing out due to
2439 precision differences. */
2443 /* If both types don't have the same signedness, then we can't consider
2444 them equal. We must check this before the STRIP_NOPS calls
2445 because they may change the signedness of the arguments. As pointers
2446 strictly don't have a signedness, require either two pointers or
2447 two non-pointers as well. */
2452 /* We cannot consider pointers to different address space equal. */
2458 /* If both types don't have the same precision, then it is not safe
2459 to strip NOPs. */
2467 /* In case both args are comparisons but with different comparison
2468 code, try to swap the comparison operands of one arg to produce
2469 a match and compare that variant. */
2473 {
2481 }
2484 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2488 /* This is needed for conversions and for COMPONENT_REF.
2489 Might as well play it safe and always test this. */
2495 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2496 We don't care about side effects in that case because the SAVE_EXPR
2497 takes care of that for us. In all other cases, two expressions are
2498 equal if they have no side effects. If we have two identical
2499 expressions with side effects that should be treated the same due
2500 to the only side effects being identical SAVE_EXPR's, that will
2501 be detected in the recursive calls below.
2502 If we are taking an invariant address of two identical objects
2503 they are necessarily equal as well. */
2510 /* Next handle constant cases, those for which we can return 1 even
2511 if ONLY_CONST is set. */
2514 {
2529 {
2530 /* If we do not distinguish between signed and unsigned zero,
2531 consider them equal. */
2534 }
2538 {
2545 {
2549 }
2551 }
2555 flags)
2557 flags));
2571 }
2576 /* Define macros to test an operand from arg0 and arg1 for equality and a
2577 variant that allows null and views null as being different from any
2578 non-null value. In the latter case, if either is null, the both
2579 must be; otherwise, do the normal comparison. */
2580 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2581 TREE_OPERAND (arg1, N), flags)
2583 #define OP_SAME_WITH_NULL(N) \
2584 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2585 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2588 {
2590 /* Two conversions are equal only if signedness and modes match. */
2592 {
2593 CASE_CONVERT:
2601 }
2611 /* For commutative ops, allow the other order. */
2619 /* If either of the pointer (or reference) expressions we are
2620 dereferencing contain a side effect, these cannot be equal,
2621 but their addresses can be. */
2628 {
2639 /* Require equal extra operands and then fall through to MEM_REF
2640 handling of the two common operands. */
2645 /* Fallthru. */
2648 /* Require equal access sizes, and similar pointer types.
2649 We can have incomplete types for array references of
2650 variable-sized arrays from the Fortran frontend
2651 though. Also verify the types are compatible. */
2658 && alias_ptr_types_compatible_p
2665 /* Operands 2 and 3 may be null.
2666 Compare the array index by value if it is constant first as we
2667 may have different types but same value here. */
2678 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2679 may be NULL when we're called to compare MEM_EXPRs. */
2694 }
2698 {
2712 /* The multiplcation operands are commutative. */
2713 /* FALLTHRU */
2721 /* Otherwise take into account this is a commutative operation. */
2734 }
2738 {
2740 /* If the CALL_EXPRs call different functions, then they
2741 clearly can not be equal. */
2743 flags))
2746 {
2750 else
2754 }
2756 /* Now see if all the arguments are the same. */
2757 {
2768 /* If we get here and both argument lists are exhausted
2769 then the CALL_EXPRs are equal. */
2771 }
2774 }
2777 /* Consider __builtin_sqrt equal to sqrt. */
2785 }
2787 #undef OP_SAME
2788 #undef OP_SAME_WITH_NULL
2789 }
2790 \f
2791 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2792 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2794 When in doubt, return 0. */
2796 static int
2798 {
2810 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2811 and see if the inner values are the same. This removes any
2812 signedness comparison, which doesn't matter here. */
2819 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2820 actual comparison operand, ARG0.
2822 First throw away any conversions to wider types
2823 already present in the operands. */
2832 {
2835 /* Make sure shorter operand is extended the right way
2836 to match the longer operand. */
2842 }
2845 }
2846 \f
2847 /* See if ARG is an expression that is either a comparison or is performing
2848 arithmetic on comparisons. The comparisons must only be comparing
2849 two different values, which will be stored in *CVAL1 and *CVAL2; if
2850 they are nonzero it means that some operands have already been found.
2851 No variables may be used anywhere else in the expression except in the
2852 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2853 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2855 If this is true, return 1. Otherwise, return zero. */
2857 static int
2859 {
2863 /* We can handle some of the tcc_expression cases here. */
2873 {
2874 /* If we've already found a CVAL1 or CVAL2, this expression is
2875 two complex to handle. */
2881 }
2884 {
2907 /* First see if we can handle the first operand, then the second. For
2908 the second operand, we know *CVAL1 can't be zero. It must be that
2909 one side of the comparison is each of the values; test for the
2910 case where this isn't true by failing if the two operands
2911 are the same. */
2920 ;
2924 ;
2925 else
2929 ;
2933 ;
2934 else
2941 }
2942 }
2943 \f
2944 /* ARG is a tree that is known to contain just arithmetic operations and
2945 comparisons. Evaluate the operations in the tree substituting NEW0 for
2946 any occurrence of OLD0 as an operand of a comparison and likewise for
2947 NEW1 and OLD1. */
2949 static tree
2952 {
2957 /* We can handle some of the tcc_expression cases here. */
2965 {
2980 {
2999 }
3000 /* Fall through - ??? */
3003 {
3007 /* We need to check both for exact equality and tree equality. The
3008 former will be true if the operand has a side-effect. In that
3009 case, we know the operand occurred exactly once. */
3022 }
3026 }
3027 }
3028 \f
3029 /* Return a tree for the case when the result of an expression is RESULT
3030 converted to TYPE and OMITTED was previously an operand of the expression
3031 but is now not needed (e.g., we folded OMITTED * 0).
3033 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3034 the conversion of RESULT to TYPE. */
3036 tree
3038 {
3041 /* If the resulting operand is an empty statement, just return the omitted
3042 statement casted to void. */
3052 }
3054 /* Return a tree for the case when the result of an expression is RESULT
3055 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3056 of the expression but are now not needed.
3058 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3059 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3060 evaluated before OMITTED2. Otherwise, if neither has side effects,
3061 just do the conversion of RESULT to TYPE. */
3063 tree
3066 {
3075 }
3077 \f
3078 /* Return a simplified tree node for the truth-negation of ARG. This
3079 never alters ARG itself. We assume that ARG is an operation that
3080 returns a truth value (0 or 1).
3082 FIXME: one would think we would fold the result, but it causes
3083 problems with the dominator optimizer. */
3085 static tree
3087 {
3092 /* If this is a comparison, we can simply invert it, except for
3093 floating-point non-equality comparisons, in which case we just
3094 enclose a TRUTH_NOT_EXPR around what we have. */
3097 {
3100 && flag_trapping_math
3111 }
3114 {
3133 /* Here we can invert either operand. We invert the first operand
3134 unless the second operand is a TRUTH_NOT_EXPR in which case our
3135 result is the XOR of the first operand with the inside of the
3136 negation of the second operand. */
3141 else
3164 {
3171 /* A COND_EXPR may have a throw as one operand, which
3172 then has void type. Just leave void operands
3173 as they are. */
3179 }
3191 CASE_CONVERT:
3195 /* ... fall through ... */
3217 }
3218 }
3220 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3221 assume that ARG is an operation that returns a truth value (0 or 1
3222 for scalars, 0 or -1 for vectors). Return the folded expression if
3223 folding is successful. Otherwise, return NULL_TREE. */
3225 static tree
3227 {
3230 ? BIT_NOT_EXPR
3233 }
3235 /* Return a simplified tree node for the truth-negation of ARG. This
3236 never alters ARG itself. We assume that ARG is an operation that
3237 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3239 tree
3241 {
3247 ? BIT_NOT_EXPR
3250 }
3252 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3253 operands are another bit-wise operation with a common input. If so,
3254 distribute the bit operations to save an operation and possibly two if
3255 constants are involved. For example, convert
3256 (A | B) & (A | C) into A | (B & C)
3257 Further simplification will occur if B and C are constants.
3259 If this optimization cannot be done, 0 will be returned. */
3261 static tree
3264 {
3265 tree common;
3275 {
3279 }
3281 {
3285 }
3287 {
3291 }
3293 {
3297 }
3298 else
3306 }
3308 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3309 with code CODE. This optimization is unsafe. */
3310 static tree
3313 {
3317 /* (A / C) +- (B / C) -> (A +- B) / C. */
3327 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3332 {
3344 }
3347 }
3348 \f
3349 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3350 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3352 static tree
3355 {
3359 {
3366 }
3380 }
3382 /* Optimize a bit-field compare.
3384 There are two cases: First is a compare against a constant and the
3385 second is a comparison of two items where the fields are at the same
3386 bit position relative to the start of a chunk (byte, halfword, word)
3387 large enough to contain it. In these cases we can avoid the shift
3388 implicit in bitfield extractions.
3390 For constants, we emit a compare of the shifted constant with the
3391 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3392 compared. For two fields at the same position, we do the ANDs with the
3393 similar mask and compare the result of the ANDs.
3395 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3396 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3397 are the left and right operands of the comparison, respectively.
3399 If the optimization described above can be done, we return the resulting
3400 tree. Otherwise we return zero. */
3402 static tree
3405 {
3408 tree unsigned_type;
3414 tree mask;
3415 tree offset;
3417 /* Get all the information about the extractions being done. If the bit size
3418 if the same as the size of the underlying object, we aren't doing an
3419 extraction at all and so can do nothing. We also don't want to
3420 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3421 then will no longer be able to replace it. */
3429 {
3430 /* If this is not a constant, we can only do something if bit positions,
3431 sizes, and signedness are the same. */
3439 }
3441 /* See if we can find a mode to refer to this field. We should be able to,
3442 but fail if we can't. */
3451 /* Set signed and unsigned types of the precision of this mode for the
3452 shifts below. */
3455 /* Compute the bit position and size for the new reference and our offset
3456 within it. If the new reference is the same size as the original, we
3457 won't optimize anything, so return zero. */
3467 /* Make the mask to be used against the extracted field. */
3474 /* If not comparing with constant, just rework the comparison
3475 and return. */
3479 unsigned_type,
3482 mask),
3485 unsigned_type,
3488 mask));
3490 /* Otherwise, we are handling the constant case. See if the constant is too
3491 big for the field. Warn and return a tree of for 0 (false) if so. We do
3492 this not only for its own sake, but to avoid having to test for this
3493 error case below. If we didn't, we might generate wrong code.
3495 For unsigned fields, the constant shifted right by the field length should
3496 be all zero. For signed fields, the high-order bits should agree with
3497 the sign bit. */
3500 {
3502 {
3506 }
3507 }
3508 else
3509 {
3512 {
3516 }
3517 }
3519 /* Single-bit compares should always be against zero. */
3521 {
3524 }
3526 /* Make a new bitfield reference, shift the constant over the
3527 appropriate number of bits and mask it with the computed mask
3528 (in case this was a signed field). If we changed it, make a new one. */
3535 mask);
3540 }
3541 \f
3542 /* Subroutine for fold_truth_andor_1: decode a field reference.
3544 If EXP is a comparison reference, we return the innermost reference.
3546 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3547 set to the starting bit number.
3549 If the innermost field can be completely contained in a mode-sized
3550 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3552 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3553 otherwise it is not changed.
3555 *PUNSIGNEDP is set to the signedness of the field.
3557 *PMASK is set to the mask used. This is either contained in a
3558 BIT_AND_EXPR or derived from the width of the field.
3560 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3562 Return 0 if this is not a component reference or is one that we can't
3563 do anything with. */
3565 static tree
3570 {
3574 tree unsigned_type;
3577 /* All the optimizations using this function assume integer fields.
3578 There are problems with FP fields since the type_for_size call
3579 below can fail for, e.g., XFmode. */
3583 /* We are interested in the bare arrangement of bits, so strip everything
3584 that doesn't affect the machine mode. However, record the type of the
3585 outermost expression if it may matter below. */
3592 {
3598 }
3607 /* If the number of bits in the reference is the same as the bitsize of
3608 the outer type, then the outer type gives the signedness. Otherwise
3609 (in case of a small bitfield) the signedness is unchanged. */
3613 /* Compute the mask to access the bitfield. */
3622 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3630 }
3632 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3633 bit positions and MASK is SIGNED. */
3635 static int
3637 {
3641 /* If this function returns true when the type of the mask is
3642 UNSIGNED, then there will be errors. In particular see
3643 gcc.c-torture/execute/990326-1.c. There does not appear to be
3644 any documentation paper trail as to why this is so. But the pre
3645 wide-int worked with that restriction and it has been preserved
3646 here. */
3651 }
3653 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3654 represents the sign bit of EXP's type. If EXP represents a sign
3655 or zero extension, also test VAL against the unextended type.
3656 The return value is the (sub)expression whose sign bit is VAL,
3657 or NULL_TREE otherwise. */
3659 tree
3661 {
3663 tree t;
3665 /* Tree EXP must have an integral type. */
3670 /* Tree VAL must be an integer constant. */
3679 /* Handle extension from a narrower type. */
3685 }
3687 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3688 to be evaluated unconditionally. */
3690 static int
3692 {
3693 /* Strip any conversions that don't change the machine mode. */
3702 /* Don't regard global variables as simple. They may be
3703 allocated in ways unknown to the compiler (shared memory,
3704 #pragma weak, etc). */
3707 /* Weakrefs are not safe to be read, since they can be NULL.
3708 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3709 have DECL_WEAK flag set. */
3711 /* Loading a static variable is unduly expensive, but global
3712 registers aren't expensive. */
3714 }
3716 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3717 to be evaluated unconditionally.
3718 I addition to simple_operand_p, we assume that comparisons, conversions,
3719 and logic-not operations are simple, if their operands are simple, too. */
3721 static bool
3723 {
3743 }
3745 \f
3746 /* The following functions are subroutines to fold_range_test and allow it to
3747 try to change a logical combination of comparisons into a range test.
3749 For example, both
3750 X == 2 || X == 3 || X == 4 || X == 5
3751 and
3752 X >= 2 && X <= 5
3753 are converted to
3754 (unsigned) (X - 2) <= 3
3756 We describe each set of comparisons as being either inside or outside
3757 a range, using a variable named like IN_P, and then describe the
3758 range with a lower and upper bound. If one of the bounds is omitted,
3759 it represents either the highest or lowest value of the type.
3761 In the comments below, we represent a range by two numbers in brackets
3762 preceded by a "+" to designate being inside that range, or a "-" to
3763 designate being outside that range, so the condition can be inverted by
3764 flipping the prefix. An omitted bound is represented by a "-". For
3765 example, "- [-, 10]" means being outside the range starting at the lowest
3766 possible value and ending at 10, in other words, being greater than 10.
3767 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3768 always false.
3770 We set up things so that the missing bounds are handled in a consistent
3771 manner so neither a missing bound nor "true" and "false" need to be
3772 handled using a special case. */
3774 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3775 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3776 and UPPER1_P are nonzero if the respective argument is an upper bound
3777 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3778 must be specified for a comparison. ARG1 will be converted to ARG0's
3779 type if both are specified. */
3781 static tree
3784 {
3785 tree tem;
3789 /* If neither arg represents infinity, do the normal operation.
3790 Else, if not a comparison, return infinity. Else handle the special
3791 comparison rules. Note that most of the cases below won't occur, but
3792 are handled for consistency. */
3795 {
3800 }
3805 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3806 for neither. In real maths, we cannot assume open ended ranges are
3807 the same. But, this is computer arithmetic, where numbers are finite.
3808 We can therefore make the transformation of any unbounded range with
3809 the value Z, Z being greater than any representable number. This permits
3810 us to treat unbounded ranges as equal. */
3814 {
3835 }
3838 }
3839 \f
3840 /* Helper routine for make_range. Perform one step for it, return
3841 new expression if the loop should continue or NULL_TREE if it should
3842 stop. */
3844 tree
3848 {
3854 {
3856 /* We can only do something if the range is testing for zero. */
3865 /* We can only do something if the range is testing for zero
3866 and if the second operand is an integer constant. Note that
3867 saying something is "in" the range we make is done by
3868 complementing IN_P since it will set in the initial case of
3869 being not equal to zero; "out" is leaving it alone. */
3876 {
3897 }
3899 /* If this is an unsigned comparison, we also know that EXP is
3900 greater than or equal to zero. We base the range tests we make
3901 on that fact, so we record it here so we can parse existing
3902 range tests. We test arg0_type since often the return type
3903 of, e.g. EQ_EXPR, is boolean. */
3905 {
3909 NULL_TREE))
3914 /* If the high bound is missing, but we have a nonzero low
3915 bound, reverse the range so it goes from zero to the low bound
3916 minus 1. */
3918 {
3923 }
3924 }
3932 /* If flag_wrapv and ARG0_TYPE is signed, make sure
3933 low and high are non-NULL, then normalize will DTRT. */
3936 {
3941 }
3943 /* (-x) IN [a,b] -> x in [-b, -a] */
3955 /* ~ X -> -X - 1 */
3964 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
3965 move a constant to the other side. */
3970 /* If EXP is signed, any overflow in the computation is undefined,
3971 so we don't worry about it so long as our computations on
3972 the bounds don't overflow. For unsigned, overflow is defined
3973 and this is exactly the right thing. */
3985 normalize:
3986 /* Check for an unsigned range which has wrapped around the maximum
3987 value thus making n_high < n_low, and normalize it. */
3989 {
3995 /* If the range is of the form +/- [ x+1, x ], we won't
3996 be able to normalize it. But then, it represents the
3997 whole range or the empty set, so make it
3998 +/- [ -, - ]. */
4002 else
4004 }
4005 else
4013 CASE_CONVERT:
4031 /* If we're converting arg0 from an unsigned type, to exp,
4032 a signed type, we will be doing the comparison as unsigned.
4033 The tests above have already verified that LOW and HIGH
4034 are both positive.
4036 So we have to ensure that we will handle large unsigned
4037 values the same way that the current signed bounds treat
4038 negative values. */
4041 {
4042 tree high_positive;
4043 tree equiv_type;
4044 /* For fixed-point modes, we need to pass the saturating flag
4045 as the 2nd parameter. */
4047 equiv_type
4050 else
4051 equiv_type
4054 /* A range without an upper bound is, naturally, unbounded.
4055 Since convert would have cropped a very large value, use
4056 the max value for the destination type. */
4057 high_positive
4064 high_positive),
4067 /* If the low bound is specified, "and" the range with the
4068 range for which the original unsigned value will be
4069 positive. */
4071 {
4074 integer_zero_node),
4075 high_positive))
4079 }
4080 else
4081 {
4082 /* Otherwise, "or" the range with the range of the input
4083 that will be interpreted as negative. */
4086 integer_zero_node),
4087 high_positive))
4091 }
4092 }
4101 }
4102 }
4104 /* Given EXP, a logical expression, set the range it is testing into
4105 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4106 actually being tested. *PLOW and *PHIGH will be made of the same
4107 type as the returned expression. If EXP is not a comparison, we
4108 will most likely not be returning a useful value and range. Set
4109 *STRICT_OVERFLOW_P to true if the return value is only valid
4110 because signed overflow is undefined; otherwise, do not change
4111 *STRICT_OVERFLOW_P. */
4113 tree
4116 {
4124 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4125 and see if we can refine the range. Some of the cases below may not
4126 happen, but it doesn't seem worth worrying about this. We "continue"
4127 the outer loop when we've changed something; otherwise we "break"
4128 the switch, which will "break" the while. */
4134 {
4140 {
4148 }
4157 }
4159 /* If EXP is a constant, we can evaluate whether this is true or false. */
4161 {
4168 }
4172 }
4173 \f
4174 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4175 type, TYPE, return an expression to test if EXP is in (or out of, depending
4176 on IN_P) the range. Return 0 if the test couldn't be created. */
4178 tree
4181 {
4184 #ifdef HAVE_canonicalize_funcptr_for_compare
4185 /* Disable this optimization for function pointer expressions
4186 on targets that require function pointer canonicalization. */
4191 #endif
4194 {
4200 }
4218 {
4220 {
4224 }
4226 }
4228 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4230 {
4234 {
4236 {
4239 etype
4241 else
4244 }
4247 }
4248 }
4250 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4251 This requires wrap-around arithmetics for the type of the expression.
4252 First make sure that arithmetics in this type is valid, then make sure
4253 that it wraps around. */
4259 {
4262 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4263 for the type in question, as we rely on this here. */
4273 else
4275 }
4285 {
4287 {
4292 }
4294 }
4302 }
4303 \f
4304 /* Return the predecessor of VAL in its type, handling the infinite case. */
4306 static tree
4308 {
4314 else
4317 }
4319 /* Return the successor of VAL in its type, handling the infinite case. */
4321 static tree
4323 {
4329 else
4332 }
4334 /* Given two ranges, see if we can merge them into one. Return 1 if we
4335 can, 0 if we can't. Set the output range into the specified parameters. */
4337 bool
4340 {
4344 tree tem;
4354 /* Make range 0 be the range that starts first, or ends last if they
4355 start at the same value. Swap them if it isn't. */
4358 || (lowequal
4361 {
4365 }
4367 /* Now flag two cases, whether the ranges are disjoint or whether the
4368 second range is totally subsumed in the first. Note that the tests
4369 below are simplified by the ones above. */
4375 /* We now have four cases, depending on whether we are including or
4376 excluding the two ranges. */
4378 {
4379 /* If they don't overlap, the result is false. If the second range
4380 is a subset it is the result. Otherwise, the range is from the start
4381 of the second to the end of the first. */
4386 else
4388 }
4391 {
4392 /* If they don't overlap, the result is the first range. If they are
4393 equal, the result is false. If the second range is a subset of the
4394 first, and the ranges begin at the same place, we go from just after
4395 the end of the second range to the end of the first. If the second
4396 range is not a subset of the first, or if it is a subset and both
4397 ranges end at the same place, the range starts at the start of the
4398 first range and ends just before the second range.
4399 Otherwise, we can't describe this as a single range. */
4405 {
4410 {
4411 /* We are in the weird situation where high0 > high1 but
4412 high1 has no successor. Punt. */
4414 }
4415 }
4417 {
4422 {
4423 /* low0 < low1 but low1 has no predecessor. Punt. */
4425 }
4426 }
4427 else
4429 }
4432 {
4433 /* If they don't overlap, the result is the second range. If the second
4434 is a subset of the first, the result is false. Otherwise,
4435 the range starts just after the first range and ends at the
4436 end of the second. */
4441 else
4442 {
4447 {
4448 /* high1 > high0 but high0 has no successor. Punt. */
4450 }
4451 }
4452 }
4454 else
4455 {
4456 /* The case where we are excluding both ranges. Here the complex case
4457 is if they don't overlap. In that case, the only time we have a
4458 range is if they are adjacent. If the second is a subset of the
4459 first, the result is the first. Otherwise, the range to exclude
4460 starts at the beginning of the first range and ends at the end of the
4461 second. */
4463 {
4468 else
4469 {
4470 /* Canonicalize - [min, x] into - [-, x]. */
4473 {
4478 /* FALLTHROUGH */
4491 }
4493 /* Canonicalize - [x, max] into - [x, -]. */
4496 {
4501 /* FALLTHROUGH */
4517 }
4519 /* The ranges might be also adjacent between the maximum and
4520 minimum values of the given type. For
4521 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4522 return + [x + 1, y - 1]. */
4524 {
4531 }
4532 else
4534 }
4535 }
4538 else
4540 }
4544 }
4545 \f
4547 /* Subroutine of fold, looking inside expressions of the form
4548 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4549 of the COND_EXPR. This function is being used also to optimize
4550 A op B ? C : A, by reversing the comparison first.
4552 Return a folded expression whose code is not a COND_EXPR
4553 anymore, or NULL_TREE if no folding opportunity is found. */
4555 static tree
4558 {
4563 tree tem;
4568 /* If we have A op 0 ? A : -A, consider applying the following
4569 transformations:
4571 A == 0? A : -A same as -A
4572 A != 0? A : -A same as A
4573 A >= 0? A : -A same as abs (A)
4574 A > 0? A : -A same as abs (A)
4575 A <= 0? A : -A same as -abs (A)
4576 A < 0? A : -A same as -abs (A)
4578 None of these transformations work for modes with signed
4579 zeros. If A is +/-0, the first two transformations will
4580 change the sign of the result (from +0 to -0, or vice
4581 versa). The last four will fix the sign of the result,
4582 even though the original expressions could be positive or
4583 negative, depending on the sign of A.
4585 Note that all these transformations are correct if A is
4586 NaN, since the two alternatives (A and -A) are also NaNs. */
4593 /* In the case that A is of the form X-Y, '-A' (arg2) may
4594 have already been folded to Y-X, check for that. */
4602 {
4616 /* Fall through. */
4638 }
4640 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4641 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4642 both transformations are correct when A is NaN: A != 0
4643 is then true, and A == 0 is false. */
4647 {
4652 }
4654 /* Try some transformations of A op B ? A : B.
4656 A == B? A : B same as B
4657 A != B? A : B same as A
4658 A >= B? A : B same as max (A, B)
4659 A > B? A : B same as max (B, A)
4660 A <= B? A : B same as min (A, B)
4661 A < B? A : B same as min (B, A)
4663 As above, these transformations don't work in the presence
4664 of signed zeros. For example, if A and B are zeros of
4665 opposite sign, the first two transformations will change
4666 the sign of the result. In the last four, the original
4667 expressions give different results for (A=+0, B=-0) and
4668 (A=-0, B=+0), but the transformed expressions do not.
4670 The first two transformations are correct if either A or B
4671 is a NaN. In the first transformation, the condition will
4672 be false, and B will indeed be chosen. In the case of the
4673 second transformation, the condition A != B will be true,
4674 and A will be chosen.
4676 The conversions to max() and min() are not correct if B is
4677 a number and A is not. The conditions in the original
4678 expressions will be false, so all four give B. The min()
4679 and max() versions would give a NaN instead. */
4682 /* Avoid these transformations if the COND_EXPR may be used
4683 as an lvalue in the C++ front-end. PR c++/19199. */
4684 && (in_gimple_form
4690 {
4695 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4697 {
4701 }
4704 {
4713 /* In C++ a ?: expression can be an lvalue, so put the
4714 operand which will be used if they are equal first
4715 so that we can convert this back to the
4716 corresponding COND_EXPR. */
4718 {
4727 }
4734 {
4743 }
4758 }
4759 }
4761 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4762 we might still be able to simplify this. For example,
4763 if C1 is one less or one more than C2, this might have started
4764 out as a MIN or MAX and been transformed by this function.
4765 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4771 {
4775 /* We can replace A with C1 in this case. */
4780 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
4781 MIN_EXPR, to preserve the signedness of the comparison. */
4783 OEP_ONLY_CONST)
4787 OEP_ONLY_CONST))
4788 {
4791 arg2));
4794 }
4798 /* If C1 is C2 - 1, this is min(A, C2), with the same care
4799 as above. */
4801 OEP_ONLY_CONST)
4805 OEP_ONLY_CONST))
4806 {
4809 arg2));
4812 }
4816 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
4817 MAX_EXPR, to preserve the signedness of the comparison. */
4819 OEP_ONLY_CONST)
4823 OEP_ONLY_CONST))
4824 {
4827 arg2));
4829 }
4833 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
4835 OEP_ONLY_CONST)
4839 OEP_ONLY_CONST))
4840 {
4843 arg2));
4845 }
4851 }
4854 }
4857 \f
4858 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4859 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
4860 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
4861 false) >= 2)
4862 #endif
4864 /* EXP is some logical combination of boolean tests. See if we can
4865 merge it into some range test. Return the new tree if so. */
4867 static tree
4870 {
4886 /* If this is an OR operation, invert both sides; we will invert
4887 again at the end. */
4891 /* If both expressions are the same, if we can merge the ranges, and we
4892 can build the range test, return it or it inverted. If one of the
4893 ranges is always true or always false, consider it to be the same
4894 expression as the other. */
4902 {
4906 }
4908 /* On machines where the branch cost is expensive, if this is a
4909 short-circuited branch and the underlying object on both sides
4910 is the same, make a non-short-circuit operation. */
4916 {
4917 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4918 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4919 which cases we can't do this. */
4927 {
4936 {
4939 WARN_STRICT_OVERFLOW_COMPARISON);
4943 }
4944 }
4945 }
4948 }
4949 \f
4950 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
4951 bit value. Arrange things so the extra bits will be set to zero if and
4952 only if C is signed-extended to its full width. If MASK is nonzero,
4953 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4955 static tree
4957 {
4960 tree temp;
4965 /* We work by getting just the sign bit into the low-order bit, then
4966 into the high-order bit, then sign-extend. We then XOR that value
4967 with C. */
4970 /* We must use a signed type in order to get an arithmetic right shift.
4971 However, we must also avoid introducing accidental overflows, so that
4972 a subsequent call to integer_zerop will work. Hence we must
4973 do the type conversion here. At this point, the constant is either
4974 zero or one, and the conversion to a signed type can never overflow.
4975 We could get an overflow if this conversion is done anywhere else. */
4984 /* If necessary, convert the type back to match the type of C. */
4989 }
4990 \f
4991 /* For an expression that has the form
4992 (A && B) || ~B
4993 or
4994 (A || B) && ~B,
4995 we can drop one of the inner expressions and simplify to
4996 A || ~B
4997 or
4998 A && ~B
4999 LOC is the location of the resulting expression. OP is the inner
5000 logical operation; the left-hand side in the examples above, while CMPOP
5001 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5002 removing a condition that guards another, as in
5003 (A != NULL && A->...) || A == NULL
5004 which we must not transform. If RHS_ONLY is true, only eliminate the
5005 right-most operand of the inner logical operation. */
5007 static tree
5010 {
5028 {
5031 {
5034 }
5035 }
5037 {
5040 {
5043 }
5044 }
5059 }
5061 /* Find ways of folding logical expressions of LHS and RHS:
5062 Try to merge two comparisons to the same innermost item.
5063 Look for range tests like "ch >= '0' && ch <= '9'".
5064 Look for combinations of simple terms on machines with expensive branches
5065 and evaluate the RHS unconditionally.
5067 For example, if we have p->a == 2 && p->b == 4 and we can make an
5068 object large enough to span both A and B, we can do this with a comparison
5069 against the object ANDed with the a mask.
5071 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5072 operations to do this with one comparison.
5074 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5075 function and the one above.
5077 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5078 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5080 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5081 two operands.
5083 We return the simplified tree or 0 if no optimization is possible. */
5085 static tree
5088 {
5089 /* If this is the "or" of two comparisons, we can do something if
5090 the comparisons are NE_EXPR. If this is the "and", we can do something
5091 if the comparisons are EQ_EXPR. I.e.,
5092 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5094 WANTED_CODE is this operation code. For single bit fields, we can
5095 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5096 comparison for one-bit fields. */
5116 /* Start by getting the comparison codes. Fail if anything is volatile.
5117 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5118 it were surrounded with a NE_EXPR. */
5127 {
5131 }
5134 {
5138 }
5149 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5152 {
5155 {
5160 }
5163 {
5169 }
5170 }
5175 /* If the RHS can be evaluated unconditionally and its operands are
5176 simple, it wins to evaluate the RHS unconditionally on machines
5177 with expensive branches. In this case, this isn't a comparison
5178 that can be merged. */
5185 {
5186 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5197 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5207 }
5209 /* See if the comparisons can be merged. Then get all the parameters for
5210 each side. */
5234 /* It must be true that the inner operation on the lhs of each
5235 comparison must be the same if we are to be able to do anything.
5236 Then see if we have constants. If not, the same must be true for
5237 the rhs's. */
5248 else
5251 /* If either comparison code is not correct for our logical operation,
5252 fail. However, we can convert a one-bit comparison against zero into
5253 the opposite comparison against that bit being set in the field. */
5257 {
5259 {
5260 /* Make the left operand unsigned, since we are only interested
5261 in the value of one bit. Otherwise we are doing the wrong
5262 thing below. */
5265 }
5266 else
5268 }
5270 /* This is analogous to the code for l_const above. */
5272 {
5274 {
5277 }
5278 else
5280 }
5282 /* See if we can find a mode that contains both fields being compared on
5283 the left. If we can't, fail. Otherwise, update all constants and masks
5284 to be relative to a field of that size. */
5289 volatilep);
5299 {
5302 }
5310 {
5317 {
5321 }
5322 }
5324 {
5331 {
5335 }
5336 }
5338 /* If the right sides are not constant, do the same for it. Also,
5339 disallow this optimization if a size or signedness mismatch occurs
5340 between the left and right sides. */
5342 {
5345 /* Make sure the two fields on the right
5346 correspond to the left without being swapped. */
5354 volatilep);
5364 {
5367 }
5376 /* Make a mask that corresponds to both fields being compared.
5377 Do this for both items being compared. If the operands are the
5378 same size and the bits being compared are in the same position
5379 then we can do this by masking both and comparing the masked
5380 results. */
5384 {
5396 }
5398 /* There is still another way we can do something: If both pairs of
5399 fields being compared are adjacent, we may be able to make a wider
5400 field containing them both.
5402 Note that we still must mask the lhs/rhs expressions. Furthermore,
5403 the mask must be shifted to account for the shift done by
5404 make_bit_field_ref. */
5409 {
5410 tree type;
5424 /* Convert to the smaller type before masking out unwanted bits. */
5427 {
5429 {
5433 }
5435 {
5439 }
5440 }
5449 }
5452 }
5454 /* Handle the case of comparisons with constants. If there is something in
5455 common between the masks, those bits of the constants must be the same.
5456 If not, the condition is always false. Test for this to avoid generating
5457 incorrect code below. */
5462 {
5464 {
5467 }
5468 else
5469 {
5472 }
5473 }
5475 /* Construct the expression we will return. First get the component
5476 reference we will make. Unless the mask is all ones the width of
5477 that field, perform the mask operation. Then compare with the
5478 merged constant. */
5488 }
5489 \f
5490 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5491 constant. */
5493 static tree
5496 {
5499 tree comp_const;
5500 tree minmax_const;
5502 tree inner;
5513 /* If something does not permit us to optimize, return the original tree. */
5521 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5522 and GT_EXPR, doing the rest with recursive calls using logical
5523 simplifications. */
5525 {
5527 {
5528 tree tem
5535 }
5538 return
5540 optimize_minmax_comparison
5542 optimize_minmax_comparison
5547 /* MAX (X, 0) == 0 -> X <= 0 */
5551 /* MAX (X, 0) == 5 -> X == 5 */
5555 /* MAX (X, 0) == -1 -> false */
5559 /* MIN (X, 0) == 0 -> X >= 0 */
5563 /* MIN (X, 0) == 5 -> false */
5566 else
5567 /* MIN (X, 0) == -1 -> X == -1 */
5572 /* MAX (X, 0) > 0 -> X > 0
5573 MAX (X, 0) > 5 -> X > 5 */
5577 /* MAX (X, 0) > -1 -> true */
5581 /* MIN (X, 0) > 0 -> false
5582 MIN (X, 0) > 5 -> false */
5585 else
5586 /* MIN (X, 0) > -1 -> X > -1 */
5591 }
5592 }
5593 \f
5594 /* T is an integer expression that is being multiplied, divided, or taken a
5595 modulus (CODE says which and what kind of divide or modulus) by a
5596 constant C. See if we can eliminate that operation by folding it with
5597 other operations already in T. WIDE_TYPE, if non-null, is a type that
5598 should be used for the computation if wider than our type.
5600 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5601 (X * 2) + (Y * 4). We must, however, be assured that either the original
5602 expression would not overflow or that overflow is undefined for the type
5603 in the language in question.
5605 If we return a non-null expression, it is an equivalent form of the
5606 original computation, but need not be in the original type.
5608 We set *STRICT_OVERFLOW_P to true if the return values depends on
5609 signed overflow being undefined. Otherwise we do not change
5610 *STRICT_OVERFLOW_P. */
5612 static tree
5615 {
5616 /* To avoid exponential search depth, refuse to allow recursion past
5617 three levels. Beyond that (1) it's highly unlikely that we'll find
5618 something interesting and (2) we've probably processed it before
5619 when we built the inner expression. */
5622 tree ret;
5627 depth++;
5629 depth--;
5632 }
5634 static tree
5637 {
5648 /* Don't deal with constants of zero here; they confuse the code below. */
5658 /* Note that we need not handle conditional operations here since fold
5659 already handles those cases. So just do arithmetic here. */
5661 {
5663 /* For a constant, we can always simplify if we are a multiply
5664 or (for divide and modulus) if it is a multiple of our constant. */
5672 /* If op0 is an expression ... */
5678 /* ... and has wrapping overflow, and its type is smaller
5679 than ctype, then we cannot pass through as widening. */
5683 /* ... or this is a truncation (t is narrower than op0),
5684 then we cannot pass through this narrowing. */
5687 /* ... or signedness changes for division or modulus,
5688 then we cannot pass through this conversion. */
5692 /* ... or has undefined overflow while the converted to
5693 type has not, we cannot do the operation in the inner type
5694 as that would introduce undefined overflow. */
5699 /* Pass the constant down and see if we can make a simplification. If
5700 we can, replace this expression with the inner simplification for
5701 possible later conversion to our or some other type. */
5706 code == MULT_EXPR
5708 strict_overflow_p))))
5713 /* If widening the type changes it from signed to unsigned, then we
5714 must avoid building ABS_EXPR itself as unsigned. */
5716 {
5720 {
5723 }
5725 }
5726 /* If the constant is negative, we cannot simplify this. */
5729 /* FALLTHROUGH */
5731 /* For division and modulus, type can't be unsigned, as e.g.
5732 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
5733 For signed types, even with wrapping overflow, this is fine. */
5742 /* If widening the type changes the signedness, then we can't perform
5743 this optimization as that changes the result. */
5747 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5753 {
5760 }
5764 /* If the second operand is constant, this is a multiplication
5765 or floor division, by a power of two, so we can treat it that
5766 way unless the multiplier or divisor overflows. Signed
5767 left-shift overflow is implementation-defined rather than
5768 undefined in C90, so do not convert signed left shift into
5769 multiplication. */
5772 /* const_binop may not detect overflow correctly,
5773 so check for it explicitly here. */
5777 size_one_node,
5778 op1)))
5782 ctype,
5784 t1),
5789 /* See if we can eliminate the operation on both sides. If we can, we
5790 can return a new PLUS or MINUS. If we can't, the only remaining
5791 cases where we can do anything are if the second operand is a
5792 constant. */
5798 /* If not multiplication, we can only do this if both operands
5799 are divisible by c. */
5802 {
5807 }
5809 /* If this was a subtraction, negate OP1 and set it to be an addition.
5810 This simplifies the logic below. */
5812 {
5814 /* If OP1 was not easily negatable, the constant may be OP0. */
5816 {
5823 }
5824 }
5829 /* If either OP1 or C are negative, this optimization is not safe for
5830 some of the division and remainder types while for others we need
5831 to change the code. */
5833 {
5841 }
5843 /* If it's a multiply or a division/modulus operation of a multiple
5844 of our constant, do the operation and verify it doesn't overflow. */
5847 {
5850 /* We allow the constant to overflow with wrapping semantics. */
5854 }
5855 else
5858 /* If we have an unsigned type, we cannot widen the operation since it
5859 will change the result if the original computation overflowed. */
5863 /* If we were able to eliminate our operation from the first side,
5864 apply our operation to the second side and reform the PLUS. */
5868 /* The last case is if we are a multiply. In that case, we can
5869 apply the distributive law to commute the multiply and addition
5870 if the multiplication of the constants doesn't overflow
5871 and overflow is defined. With undefined overflow
5872 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
5878 op1);
5883 /* We have a special case here if we are doing something like
5884 (C * 8) % 4 since we know that's zero. */
5887 /* If the multiplication can overflow we cannot optimize this. */
5891 {
5894 }
5896 /* ... fall through ... */
5900 /* If we can extract our operation from the LHS, do so and return a
5901 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5902 do something only if the second operand is a constant. */
5916 /* If these are the same operation types, we can associate them
5917 assuming no overflow. */
5919 {
5931 }
5933 /* If these operations "cancel" each other, we have the main
5934 optimizations of this pass, which occur when either constant is a
5935 multiple of the other, in which case we replace this with either an
5936 operation or CODE or TCODE.
5938 If we have an unsigned type, we cannot do this since it will change
5939 the result if the original computation overflowed. */
5946 {
5948 {
5955 }
5957 {
5964 }
5965 }
5970 }
5973 }
5974 \f
5975 /* Return a node which has the indicated constant VALUE (either 0 or
5976 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
5977 and is of the indicated TYPE. */
5979 tree
5981 {
5990 else
5992 }
5995 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
5996 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
5997 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
5998 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
5999 COND is the first argument to CODE; otherwise (as in the example
6000 given here), it is the second argument. TYPE is the type of the
6001 original expression. Return NULL_TREE if no simplification is
6002 possible. */
6004 static tree
6009 {
6019 {
6023 /* If this operand throws an expression, then it does not make
6024 sense to try to perform a logical or arithmetic operation
6025 involving it. */
6030 }
6031 else
6032 {
6037 }
6042 /* This transformation is only worthwhile if we don't have to wrap ARG
6043 in a SAVE_EXPR and the operation can be simplified without recursing
6044 on at least one of the branches once its pushed inside the COND_EXPR. */
6053 {
6057 else
6059 }
6061 {
6065 else
6067 }
6069 /* Check that we have simplified at least one of the branches. */
6074 }
6076 \f
6077 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6079 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6080 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6081 ADDEND is the same as X.
6083 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6084 and finite. The problematic cases are when X is zero, and its mode
6085 has signed zeros. In the case of rounding towards -infinity,
6086 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6087 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6089 bool
6091 {
6095 /* Don't allow the fold with -fsignaling-nans. */
6099 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6103 /* In a vector or complex, we would need to check the sign of all zeros. */
6107 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6111 /* The mode has signed zeros, and we have to honor their sign.
6112 In this situation, there is only one case we can return true for.
6113 X - 0 is the same as X unless rounding towards -infinity is
6114 supported. */
6116 }
6118 /* Subroutine of fold() that checks comparisons of built-in math
6119 functions against real constants.
6121 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6122 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6123 is the type of the result and ARG0 and ARG1 are the operands of the
6124 comparison. ARG1 must be a TREE_REAL_CST.
6126 The function returns the constant folded tree if a simplification
6127 can be made, and NULL_TREE otherwise. */
6129 static tree
6133 {
6134 REAL_VALUE_TYPE c;
6137 {
6143 {
6144 /* sqrt(x) < y is always false, if y is negative. */
6148 /* sqrt(x) > y is always true, if y is negative and we
6149 don't care about NaNs, i.e. negative values of x. */
6153 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6156 }
6158 {
6159 REAL_VALUE_TYPE c2;
6165 {
6166 /* sqrt(x) > y is x == +Inf, when y is very large. */
6171 /* sqrt(x) > y is always false, when y is very large
6172 and we don't care about infinities. */
6174 }
6176 /* sqrt(x) > c is the same as x > c*c. */
6179 }
6181 {
6182 REAL_VALUE_TYPE c2;
6188 {
6189 /* sqrt(x) < y is always true, when y is a very large
6190 value and we don't care about NaNs or Infinities. */
6194 /* sqrt(x) < y is x != +Inf when y is very large and we
6195 don't care about NaNs. */
6200 /* sqrt(x) < y is x >= 0 when y is very large and we
6201 don't care about Infinities. */
6206 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6211 dconst0)),
6214 c2)));
6215 }
6217 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6222 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6227 dconst0)),
6230 c2)));
6231 }
6232 }
6235 }
6237 /* Subroutine of fold() that optimizes comparisons against Infinities,
6238 either +Inf or -Inf.
6240 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6241 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6242 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6244 The function returns the constant folded tree if a simplification
6245 can be made, and NULL_TREE otherwise. */
6247 static tree
6250 {
6251 machine_mode mode;
6252 REAL_VALUE_TYPE max;
6253 tree temp;
6258 /* For negative infinity swap the sense of the comparison. */
6264 {
6266 /* x > +Inf is always false, if with ignore sNANs. */
6272 /* x <= +Inf is always true, if we don't case about NaNs. */
6276 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6282 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6288 /* x < +Inf is always equal to x <= DBL_MAX. */
6294 /* x != +Inf is always equal to !(x > DBL_MAX). */
6306 }
6309 }
6311 /* Subroutine of fold() that optimizes comparisons of a division by
6312 a nonzero integer constant against an integer constant, i.e.
6313 X/C1 op C2.
6315 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6316 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6317 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6319 The function returns the constant folded tree if a simplification
6320 can be made, and NULL_TREE otherwise. */
6322 static tree
6325 {
6333 /* We have to do this the hard way to detect unsigned overflow.
6334 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6340 {
6345 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6349 }
6351 {
6355 {
6374 }
6375 }
6376 else
6377 {
6378 /* A negative divisor reverses the relational operators. */
6384 {
6403 }
6404 }
6407 {
6428 {
6431 }
6436 {
6439 }
6444 {
6447 }
6452 {
6455 }
6460 }
6463 }
6466 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6467 equality/inequality test, then return a simplified form of the test
6468 using a sign testing. Otherwise return NULL. TYPE is the desired
6469 result type. */
6471 static tree
6474 tree result_type)
6475 {
6476 /* If this is testing a single bit, we can optimize the test. */
6480 {
6481 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6482 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6486 /* This is only a win if casting to a signed type is cheap,
6487 i.e. when arg00's type is not a partial mode. */
6490 {
6493 result_type,
6496 }
6497 }
6500 }
6502 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6503 equality/inequality test, then return a simplified form of
6504 the test using shifts and logical operations. Otherwise return
6505 NULL. TYPE is the desired result type. */
6507 tree
6510 {
6511 /* If this is testing a single bit, we can optimize the test. */
6515 {
6524 /* First, see if we can fold the single bit test into a sign-bit
6525 test. */
6527 result_type);
6531 /* Otherwise we have (A & C) != 0 where C is a single bit,
6532 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6533 Similarly for (A & C) == 0. */
6535 /* If INNER is a right shift of a constant and it plus BITNUM does
6536 not overflow, adjust BITNUM and INNER. */
6542 {
6545 }
6547 /* If we are going to be able to omit the AND below, we must do our
6548 operations as unsigned. If we must use the AND, we have a choice.
6549 Normally unsigned is faster, but for some machines signed is. */
6550 #ifdef LOAD_EXTEND_OP
6553 #else
6555 #endif
6571 /* Put the AND last so it can combine with more things. */
6574 /* Make sure to return the proper type. */
6578 }
6580 }
6582 /* Check whether we are allowed to reorder operands arg0 and arg1,
6583 such that the evaluation of arg1 occurs before arg0. */
6585 static bool
6587 {
6594 }
6596 /* Test whether it is preferable two swap two operands, ARG0 and
6597 ARG1, for example because ARG0 is an integer constant and ARG1
6598 isn't. If REORDER is true, only recommend swapping if we can
6599 evaluate the operands in reverse order. */
6601 bool
6603 {
6621 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6622 for commutative and comparison operators. Ensuring a canonical
6623 form allows the optimizers to find additional redundancies without
6624 having to explicitly check for both orderings. */
6630 /* Put SSA_NAMEs last. */
6636 /* Put variables last. */
6643 }
6645 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6646 ARG0 is extended to a wider type. */
6648 static tree
6651 {
6653 tree arg1_unw;
6662 #ifdef HAVE_canonicalize_funcptr_for_compare
6663 /* Disable this optimization if we're casting a function pointer
6664 type on targets that require function pointer canonicalization. */
6669 #endif
6676 /* If possible, express the comparison in the shorter mode. */
6696 /* If we are comparing with the integer that does not fit into the range
6697 of the shorter type, the result is known. */
6708 {
6735 }
6738 }
6740 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6741 ARG0 just the signedness is changed. */
6743 static tree
6746 {
6747 tree arg0_inner;
6757 #ifdef HAVE_canonicalize_funcptr_for_compare
6758 /* Disable this optimization if we're casting a function pointer
6759 type on targets that require function pointer canonicalization. */
6764 #endif
6785 else
6789 }
6792 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6793 means A >= Y && A != MAX, but in this case we know that
6794 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6796 static tree
6798 {
6805 else
6814 {
6817 }
6819 {
6822 }
6823 else
6830 {
6831 /* Convert the pointer types into integer before taking the difference. */
6835 }
6836 else
6843 }
6845 /* Fold a sum or difference of at least one multiplication.
6846 Returns the folded tree or NULL if no simplification could be made. */
6848 static tree
6851 {
6855 /* (A * C) +- (B * C) -> (A+-B) * C.
6856 (A * C) +- A -> A * (C+-1).
6857 We are most concerned about the case where C is a constant,
6858 but other combinations show up during loop reduction. Since
6859 it is not difficult, try all four possibilities. */
6862 {
6865 }
6867 {
6870 }
6871 else
6872 {
6873 /* We cannot generate constant 1 for fract. */
6878 }
6880 {
6883 }
6885 {
6887 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6888 the purpose of this canonicalization. */
6892 {
6895 }
6896 else
6898 }
6899 else
6900 {
6901 /* We cannot generate constant 1 for fract. */
6906 }
6918 /* No identical multiplicands; see if we can find a common
6919 power-of-two factor in non-power-of-two multiplies. This
6920 can help in multi-dimensional array access. */
6923 {
6926 tree maybe_same;
6930 /* Move min of absolute values to int11. */
6932 {
6937 }
6938 else
6942 /* The remainder should not be a constant, otherwise we
6943 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6944 increased the number of multiplications necessary. */
6946 {
6954 }
6955 }
6965 }
6967 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6968 specified by EXPR into the buffer PTR of length LEN bytes.
6969 Return the number of bytes placed in the buffer, or zero
6970 upon failure. */
6972 static int
6974 {
6988 {
6990 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
6991 number of bytes. */
6995 {
7002 else
7004 }
7005 else
7010 }
7012 }
7015 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7016 specified by EXPR into the buffer PTR of length LEN bytes.
7017 Return the number of bytes placed in the buffer, or zero
7018 upon failure. */
7020 static int
7022 {
7026 FIXED_VALUE_TYPE value;
7042 }
7045 /* Subroutine of native_encode_expr. Encode the REAL_CST
7046 specified by EXPR into the buffer PTR of length LEN bytes.
7047 Return the number of bytes placed in the buffer, or zero
7048 upon failure. */
7050 static int
7052 {
7058 /* There are always 32 bits in each long, no matter the size of
7059 the hosts long. We handle floating point representations with
7060 up to 192 bits. */
7074 {
7079 {
7086 else
7088 }
7089 else
7095 }
7097 }
7099 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7100 specified by EXPR into the buffer PTR of length LEN bytes.
7101 Return the number of bytes placed in the buffer, or zero
7102 upon failure. */
7104 static int
7106 {
7108 tree part;
7123 }
7126 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7127 specified by EXPR into the buffer PTR of length LEN bytes.
7128 Return the number of bytes placed in the buffer, or zero
7129 upon failure. */
7131 static int
7133 {
7143 {
7145 {
7148 }
7159 }
7161 }
7164 /* Subroutine of native_encode_expr. Encode the STRING_CST
7165 specified by EXPR into the buffer PTR of length LEN bytes.
7166 Return the number of bytes placed in the buffer, or zero
7167 upon failure. */
7169 static int
7171 {
7173 HOST_WIDE_INT total_bytes;
7187 {
7190 {
7193 }
7196 }
7197 else
7200 }
7203 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7204 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7205 buffer PTR of length LEN bytes. If OFF is not -1 then start
7206 the encoding at byte offset OFF and encode at most LEN bytes.
7207 Return the number of bytes placed in the buffer, or zero upon failure. */
7209 int
7211 {
7213 {
7234 }
7235 }
7238 /* Subroutine of native_interpret_expr. Interpret the contents of
7239 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7240 If the buffer cannot be interpreted, return NULL_TREE. */
7242 static tree
7244 {
7254 }
7257 /* Subroutine of native_interpret_expr. Interpret the contents of
7258 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7259 If the buffer cannot be interpreted, return NULL_TREE. */
7261 static tree
7263 {
7265 double_int result;
7266 FIXED_VALUE_TYPE fixed_value;
7276 }
7279 /* Subroutine of native_interpret_expr. Interpret the contents of
7280 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7281 If the buffer cannot be interpreted, return NULL_TREE. */
7283 static tree
7285 {
7290 /* There are always 32 bits in each long, no matter the size of
7291 the hosts long. We handle floating point representations with
7292 up to 192 bits. */
7293 REAL_VALUE_TYPE r;
7304 {
7307 {
7314 else
7316 }
7317 else
7322 }
7326 }
7329 /* Subroutine of native_interpret_expr. Interpret the contents of
7330 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7331 If the buffer cannot be interpreted, return NULL_TREE. */
7333 static tree
7335 {
7350 }
7353 /* Subroutine of native_interpret_expr. Interpret the contents of
7354 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7355 If the buffer cannot be interpreted, return NULL_TREE. */
7357 static tree
7359 {
7372 {
7377 }
7379 }
7382 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7383 the buffer PTR of length LEN as a constant of type TYPE. For
7384 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7385 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7386 return NULL_TREE. */
7388 tree
7390 {
7392 {
7414 }
7415 }
7417 /* Returns true if we can interpret the contents of a native encoding
7418 as TYPE. */
7420 static bool
7422 {
7424 {
7437 }
7438 }
7440 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7441 TYPE at compile-time. If we're unable to perform the conversion
7442 return NULL_TREE. */
7444 static tree
7446 {
7447 /* We support up to 512-bit values (for V8DFmode). */
7451 /* Check that the host and target are sane. */
7460 }
7462 /* Build an expression for the address of T. Folds away INDIRECT_REF
7463 to avoid confusing the gimplify process. */
7465 tree
7467 {
7468 /* The size of the object is not relevant when talking about its address. */
7473 {
7478 }
7488 {
7493 }
7494 else
7498 }
7500 /* Build an expression for the address of T. */
7502 tree
7504 {
7508 }
7512 /* Fold a unary expression of code CODE and type TYPE with operand
7513 OP0. Return the folded expression if folding is successful.
7514 Otherwise, return NULL_TREE. */
7516 tree
7518 {
7519 tree tem;
7520 tree arg0;
7532 {
7535 {
7536 /* Don't use STRIP_NOPS, because signedness of argument type
7537 matters. */
7539 }
7540 else
7541 {
7542 /* Strip any conversions that don't change the mode. This
7543 is safe for every expression, except for a comparison
7544 expression because its signedness is derived from its
7545 operands.
7547 Note that this is done as an internal manipulation within
7548 the constant folder, in order to find the simplest
7549 representation of the arguments so that their form can be
7550 studied. In any cases, the appropriate type conversions
7551 should be put back in the tree that will get out of the
7552 constant folder. */
7554 }
7555 }
7558 {
7565 {
7579 /* If this was a conversion, and all we did was to move into
7580 inside the COND_EXPR, bring it back out. But leave it if
7581 it is a conversion from integer to integer and the
7582 result precision is no wider than a word since such a
7583 conversion is cheap and may be optimized away by combine,
7584 while it couldn't if it were outside the COND_EXPR. Then return
7585 so we don't get into an infinite recursion loop taking the
7586 conversion out and then back in. */
7598 && (INTEGRAL_TYPE_P
7611 }
7612 }
7615 {
7621 CASE_CONVERT:
7625 {
7626 /* If we have (type) (a CMP b) and type is an integral type, return
7627 new expression involving the new type. Canonicalize
7628 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7629 non-integral type.
7630 Do not fold the result as that would not simplify further, also
7631 folding again results in recursions. */
7641 }
7643 /* Handle (T *)&A.B.C for A being of type T and B and C
7644 living at offset zero. This occurs frequently in
7645 C++ upcasting and then accessing the base. */
7649 {
7651 tree offset;
7652 machine_mode mode;
7657 /* If the reference was to a (constant) zero offset, we can use
7658 the address of the base if it has the same base type
7659 as the result type and the pointer type is unqualified. */
7666 }
7670 /* Detect assigning a bitfield. */
7672 && DECL_BIT_FIELD
7674 {
7675 /* Don't leave an assignment inside a conversion
7676 unless assigning a bitfield. */
7678 /* First do the assignment, then return converted constant. */
7683 }
7685 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7686 constants (if x has signed type, the sign bit cannot be set
7687 in c). This folds extension into the BIT_AND_EXPR.
7688 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7689 very likely don't have maximal range for their precision and this
7690 transformation effectively doesn't preserve non-maximal ranges. */
7694 {
7705 <= HOST_BITS_PER_WIDE_INT
7707 {
7711 cst &= HOST_WIDE_INT_M1U
7714 #ifdef LOAD_EXTEND_OP
7716 && !flag_syntax_only
7719 {
7723 }
7724 #endif
7725 }
7727 {
7732 }
7733 }
7735 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7736 when one of the new casts will fold away. Conservatively we assume
7737 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7744 {
7748 return fold_build_pointer_plus_loc
7750 }
7752 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7753 of the same precision, and X is an integer type not narrower than
7754 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7760 {
7766 }
7768 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7769 type of X and Y (integer types only). */
7774 {
7775 /* Be careful not to introduce new overflows. */
7776 tree mult_type;
7779 else
7783 {
7790 }
7791 }
7821 /* Convert fabs((double)float) into (double)fabsf(float). */
7824 {
7830 targ0));
7831 }
7832 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7836 /* Strip sign ops from argument. */
7838 {
7843 }
7850 {
7856 }
7858 {
7863 }
7871 /* Convert ~ (-A) to A - 1. */
7876 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7885 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7900 /* Perform BIT_NOT_EXPR on each element individually. */
7902 {
7904 tree elem;
7909 {
7915 }
7918 }
7923 /* Note that the operand of this must be an int
7924 and its values must be 0 or 1.
7925 ("true" is a fixed value perhaps depending on the language,
7926 but we don't handle values other than 1 correctly yet.) */
7938 {
7946 }
7948 {
7953 }
7955 {
7959 {
7968 }
7969 }
7978 {
7986 }
7988 {
7992 }
7994 {
7998 {
8007 }
8008 }
8012 /* Fold *&X to X if X is an lvalue. */
8014 {
8021 }
8028 {
8047 else
8051 {
8055 }
8058 }
8063 {
8077 {
8082 }
8085 {
8089 }
8092 }
8097 }
8100 /* If the operation was a conversion do _not_ mark a resulting constant
8101 with TREE_OVERFLOW if the original constant was not. These conversions
8102 have implementation defined behavior and retaining the TREE_OVERFLOW
8103 flag here would confuse later passes such as VRP. */
8104 tree
8107 {
8116 }
8118 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8119 operands OP0 and OP1. LOC is the location of the resulting expression.
8120 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8121 Return the folded expression if folding is successful. Otherwise,
8122 return NULL_TREE. */
8123 static tree
8126 {
8127 tree tem;
8129 /* We only do these simplifications if we are optimizing. */
8133 /* Check for things like (A || B) && (A || C). We can convert this
8134 to A || (B && C). Note that either operator can be any of the four
8135 truth and/or operations and the transformation will still be
8136 valid. Also note that we only care about order for the
8137 ANDIF and ORIF operators. If B contains side effects, this
8138 might change the truth-value of A. */
8145 {
8165 /* This case if tricky because we must either have commutative
8166 operators or else A10 must not have side-effects. */
8172 a01);
8173 }
8175 /* See if we can build a range comparison. */
8181 {
8185 }
8189 {
8193 }
8195 /* Check for the possibility of merging component references. If our
8196 lhs is another similar operation, try to merge its rhs with our
8197 rhs. Then try to merge our lhs and rhs. */
8211 {
8218 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8219 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8220 We don't want to pack more than two leafs to a non-IF AND/OR
8221 expression.
8222 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8223 equal to IF-CODE, then we don't want to add right-hand operand.
8224 If the inner right-hand side of left-hand operand has
8225 side-effects, or isn't simple, then we can't add to it,
8226 as otherwise we might destroy if-sequence. */
8229 /* Needed for sequence points to handle trappings, and
8230 side-effects. */
8232 {
8234 arg1);
8236 tem);
8237 }
8238 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8239 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8242 /* Needed for sequence points to handle trappings, and
8243 side-effects. */
8245 {
8250 }
8251 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8252 into (A OR B).
8253 For sequence point consistancy, we need to check for trapping,
8254 and side-effects. */
8258 }
8261 }
8263 /* Fold a binary expression of code CODE and type TYPE with operands
8264 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8265 Return the folded expression if folding is successful. Otherwise,
8266 return NULL_TREE. */
8268 static tree
8270 {
8277 else
8280 /* MIN (MAX (a, b), b) == b. */
8285 /* MIN (MAX (b, a), b) == b. */
8291 /* MIN (a, MAX (a, b)) == a. */
8297 /* MIN (a, MAX (b, a)) == a. */
8304 }
8306 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8307 by changing CODE to reduce the magnitude of constants involved in
8308 ARG0 of the comparison.
8309 Returns a canonicalized comparison tree if a simplification was
8310 possible, otherwise returns NULL_TREE.
8311 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8312 valid if signed overflow is undefined. */
8314 static tree
8318 {
8324 /* Match A +- CST code arg1 and CST code arg1. We can change the
8325 first form only if overflow is undefined. */
8327 /* In principle pointers also have undefined overflow behavior,
8328 but that causes problems elsewhere. */
8336 /* Identify the constant in arg0 and its sign. */
8339 else
8343 /* Overflowed constants and zero will cause problems. */
8348 /* See if we can reduce the magnitude of the constant in
8349 arg0 by changing the comparison code. */
8351 {
8352 /* CST <= arg1 -> CST-1 < arg1. */
8355 /* -CST < arg1 -> -CST-1 <= arg1. */
8358 /* CST > arg1 -> CST-1 >= arg1. */
8361 /* -CST >= arg1 -> -CST-1 > arg1. */
8364 else
8366 /* arg1 code' CST' might be more canonical. */
8368 }
8369 else
8370 {
8371 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8375 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8379 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8383 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8387 else
8390 }
8392 /* Now build the constant reduced in magnitude. But not if that
8393 would produce one outside of its types range. */
8401 /* We cannot swap the comparison here as that would cause us to
8402 endlessly recurse. */
8411 /* If swapping might yield to a more canonical form, do so. */
8414 else
8416 }
8418 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8419 overflow further. Try to decrease the magnitude of constants involved
8420 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8421 and put sole constants at the second argument position.
8422 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8424 static tree
8427 {
8428 tree t;
8433 /* Try canonicalization by simplifying arg0. */
8438 {
8442 }
8444 /* Try canonicalization by simplifying arg1 using the swapped
8445 comparison. */
8453 }
8455 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8456 space. This is used to avoid issuing overflow warnings for
8457 expressions like &p->x which can not wrap. */
8459 static bool
8461 {
8468 wide_int wi_offset;
8474 else
8490 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8491 array. */
8493 {
8494 HOST_WIDE_INT base_size;
8499 }
8502 }
8504 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8505 kind INTEGER_CST. This makes sure to properly sign-extend the
8506 constant. */
8508 static HOST_WIDE_INT
8510 {
8516 }
8518 /* Subroutine of fold_binary. This routine performs all of the
8519 transformations that are common to the equality/inequality
8520 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8521 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8522 fold_binary should call fold_binary. Fold a comparison with
8523 tree code CODE and type TYPE with operands OP0 and OP1. Return
8524 the folded comparison or NULL_TREE. */
8526 static tree
8529 {
8539 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8546 {
8547 const enum tree_code
8554 /* If the constant operation overflowed this can be
8555 simplified as a comparison against INT_MAX/INT_MIN. */
8558 {
8562 /* Get the sign of the constant on the lhs if the
8563 operation were VARIABLE + CONST1. */
8567 /* The sign of the constant determines if we overflowed
8568 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8569 Canonicalize to the INT_MIN overflow by swapping the comparison
8570 if necessary. */
8574 /* We now can look at the canonicalized case
8575 VARIABLE + 1 CODE2 INT_MIN
8576 and decide on the result. */
8578 {
8582 return
8588 return
8593 }
8594 }
8595 else
8596 {
8599 "when changing X +- C1 cmp C2 to "
8601 WARN_STRICT_OVERFLOW_COMPARISON);
8603 }
8604 }
8606 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8608 && equality_code
8610 {
8611 /* ??? The transformation is valid for the other operators if overflow
8612 is undefined for the type, but performing it here badly interacts
8613 with the transformation in fold_cond_expr_with_comparison which
8614 attempts to synthetize ABS_EXPR. */
8618 WARN_STRICT_OVERFLOW_COMPARISON);
8621 }
8623 /* For comparisons of pointers we can decompose it to a compile time
8624 comparison of the base objects and the offsets into the object.
8625 This requires at least one operand being an ADDR_EXPR or a
8626 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8632 {
8635 machine_mode mode;
8639 /* Get base and offset for the access. Strip ADDR_EXPR for
8640 get_inner_reference, but put it back by stripping INDIRECT_REF
8641 off the base object if possible. indirect_baseN will be true
8642 if baseN is not an address but refers to the object itself. */
8645 {
8651 else
8653 }
8655 {
8659 {
8662 }
8665 {
8670 {
8673 }
8674 }
8675 }
8679 {
8685 else
8687 }
8689 {
8693 {
8696 }
8699 {
8704 {
8707 }
8708 }
8709 }
8711 /* A local variable can never be pointed to by
8712 the default SSA name of an incoming parameter. */
8714 && indirect_base0
8717 && !indirect_base1
8722 && indirect_base1
8725 && !indirect_base0
8729 {
8734 }
8735 /* If we have equivalent bases we might be able to simplify. */
8738 {
8739 /* We can fold this expression to a constant if the non-constant
8740 offset parts are equal. */
8749 {
8755 "occur when comparing P +- C1 with "
8757 WARN_STRICT_OVERFLOW_CONDITIONAL);
8760 {
8774 }
8775 }
8776 /* We can simplify the comparison to a comparison of the variable
8777 offset parts if the constant offset parts are equal.
8778 Be careful to use signed sizetype here because otherwise we
8779 mess with array offsets in the wrong way. This is possible
8780 because pointer arithmetic is restricted to retain within an
8781 object and overflow on pointer differences is undefined as of
8782 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8784 && (equality_code
8787 {
8788 /* By converting to signed sizetype we cover middle-end pointer
8789 arithmetic which operates on unsigned pointer types of size
8790 type size and ARRAY_REF offsets which are properly sign or
8791 zero extended from their type in case it is narrower than
8792 sizetype. */
8795 else
8799 else
8806 "occur when comparing P +- C1 with "
8808 WARN_STRICT_OVERFLOW_COMPARISON);
8811 }
8812 }
8813 /* For non-equal bases we can simplify if they are addresses
8814 of local binding decls or constants. */
8816 /* We know that !operand_equal_p (base0, base1, 0)
8817 because the if condition was false. But make
8818 sure two decls are not the same. */
8832 {
8839 }
8840 /* For equal offsets we can simplify to a comparison of the
8841 base addresses. */
8843 && (indirect_base0
8845 && (indirect_base1
8850 {
8856 }
8857 }
8859 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8860 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8861 the resulting offset is smaller in absolute value than the
8862 original one and has the same sign. */
8870 {
8875 tree cst;
8877 "occur when combining constants around "
8880 /* Put the constant on the side where it doesn't overflow and is
8881 of lower absolute value and of same sign than before. */
8888 {
8891 variable1,
8895 }
8903 {
8909 variable2);
8910 }
8911 }
8913 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8914 signed arithmetic case. That form is created by the compiler
8915 often enough for folding it to be of value. One example is in
8916 computing loop trip counts after Operator Strength Reduction. */
8922 {
8928 /* Handle unfolded multiplication by zero. */
8933 "eliminating multiplication in comparison "
8935 WARN_STRICT_OVERFLOW_COMPARISON);
8937 /* If const1 is negative we swap the sense of the comparison. */
8942 }
8949 {
8957 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8963 /* (-a) CMP (-b) -> b CMP a */
8970 {
8971 REAL_VALUE_TYPE cst;
8974 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8981 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8982 /* a CMP (-0) -> a CMP 0 */
8987 /* x != NaN is always true, other ops are always false. */
8990 {
8993 }
8995 /* Fold comparisons against infinity. */
8998 {
9002 }
9003 }
9005 /* If this is a comparison of a real constant with a PLUS_EXPR
9006 or a MINUS_EXPR of a real constant, we can convert it into a
9007 comparison with a revised real constant as long as no overflow
9008 occurs when unsafe_math_optimizations are enabled. */
9020 /* Likewise, we can simplify a comparison of a real constant with
9021 a MINUS_EXPR whose first operand is also a real constant, i.e.
9022 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9023 floating-point types only if -fassociative-math is set. */
9029 arg1))
9034 /* Fold comparisons against built-in math functions. */
9036 && flag_unsafe_math_optimizations
9038 {
9042 {
9046 }
9047 }
9048 }
9052 {
9053 /* If we are widening one operand of an integer comparison,
9054 see if the other operand is similarly being widened. Perhaps we
9055 can do the comparison in the narrower type. */
9060 /* Or if we are changing signedness. */
9064 }
9066 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9067 constant, we can simplify it. */
9072 {
9076 }
9078 /* Simplify comparison of something with itself. (For IEEE
9079 floating-point, we can only do some of these simplifications.) */
9081 {
9083 {
9098 /* For NE, we can only do this simplification if integer
9099 or we don't honor IEEE floating point NaNs. */
9103 /* ... fall through ... */
9109 }
9110 }
9112 /* If we are comparing an expression that just has comparisons
9113 of two integer values, arithmetic expressions of those comparisons,
9114 and constants, we can simplify it. There are only three cases
9115 to check: the two values can either be equal, the first can be
9116 greater, or the second can be greater. Fold the expression for
9117 those three values. Since each value must be 0 or 1, we have
9118 eight possibilities, each of which corresponds to the constant 0
9119 or 1 or one of the six possible comparisons.
9121 This handles common cases like (a > b) == 0 but also handles
9122 expressions like ((x > y) - (y > x)) > 0, which supposedly
9123 occur in macroized code. */
9126 {
9131 /* Don't handle degenerate cases here; they should already
9132 have been handled anyway. */
9141 {
9145 /* We can't just pass T to eval_subst in case cval1 or cval2
9146 was the same as ARG1. */
9148 tree high_result
9152 arg1);
9153 tree equal_result
9157 arg1);
9158 tree low_result
9162 arg1);
9164 /* All three of these results should be 0 or 1. Confirm they are.
9165 Then use those values to select the proper code to use. */
9170 {
9171 /* Make a 3-bit mask with the high-order bit being the
9172 value for `>', the next for '=', and the low for '<'. */
9176 {
9178 /* Always false. */
9199 /* Always true. */
9201 }
9204 {
9208 }
9210 }
9211 }
9212 }
9214 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9215 into a single range test. */
9223 {
9227 }
9229 /* Fold ~X op ~Y as Y op X. */
9232 {
9238 }
9240 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9243 {
9249 }
9252 }
9255 /* Subroutine of fold_binary. Optimize complex multiplications of the
9256 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9257 argument EXPR represents the expression "z" of type TYPE. */
9259 static tree
9261 {
9266 {
9269 }
9271 {
9274 }
9275 else
9276 {
9280 }
9289 }
9292 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9293 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9294 guarantees that P and N have the same least significant log2(M) bits.
9295 N is not otherwise constrained. In particular, N is not normalized to
9296 0 <= N < M as is common. In general, the precise value of P is unknown.
9297 M is chosen as large as possible such that constant N can be determined.
9299 Returns M and sets *RESIDUE to N.
9301 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9302 account. This is not always possible due to PR 35705.
9303 */
9305 static unsigned HOST_WIDE_INT
9308 {
9315 {
9320 }
9322 {
9330 allow_func_align);
9336 {
9339 }
9341 {
9344 {
9347 /* Compute the greatest power-of-2 divisor of op1. */
9351 /* If align is non-zero and less than *modulus, replace
9352 *modulus with align., If align is 0, then either op1 is 0
9353 or the greatest power-of-2 divisor of op1 doesn't fit in an
9354 unsigned HOST_WIDE_INT. In either case, no additional
9355 constraint is imposed. */
9360 }
9361 }
9362 }
9364 /* If we get here, we were unable to determine anything useful about the
9365 expression. */
9367 }
9369 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9370 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9372 static bool
9374 {
9378 {
9381 }
9383 {
9389 else
9391 }
9392 else
9398 }
9400 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9401 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9402 NULL_TREE otherwise. */
9404 static tree
9406 {
9423 {
9427 }
9430 {
9436 }
9437 else
9439 }
9441 /* Try to fold a pointer difference of type TYPE two address expressions of
9442 array references AREF0 and AREF1 using location LOC. Return a
9443 simplified expression for the difference or NULL_TREE. */
9445 static tree
9448 {
9453 /* If the bases are array references as well, recurse. If the bases
9454 are pointer indirections compute the difference of the pointers.
9455 If the bases are equal, we are set. */
9458 && (base_offset
9466 {
9472 base_offset,
9475 }
9477 }
9479 /* If the real or vector real constant CST of type TYPE has an exact
9480 inverse, return it, else return NULL. */
9482 tree
9484 {
9485 REAL_VALUE_TYPE r;
9487 machine_mode mode;
9491 {
9507 {
9512 }
9518 }
9519 }
9521 /* Mask out the tz least significant bits of X of type TYPE where
9522 tz is the number of trailing zeroes in Y. */
9523 static wide_int
9525 {
9530 }
9532 /* Return true when T is an address and is known to be nonzero.
9533 For floating point we further ensure that T is not denormal.
9534 Similar logic is present in nonzero_address in rtlanal.h.
9536 If the return value is based on the assumption that signed overflow
9537 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9538 change *STRICT_OVERFLOW_P. */
9540 static bool
9542 {
9546 /* Doing something useful for floating point would need more work. */
9552 {
9555 strict_overflow_p);
9561 strict_overflow_p);
9569 }
9572 {
9575 strict_overflow_p);
9583 strict_overflow_p);
9598 strict_overflow_p);
9602 strict_overflow_p);
9605 {
9617 }
9621 }
9623 }
9625 /* Return true when T is an address and is known to be nonzero.
9626 Handle warnings about undefined signed overflow. */
9628 static bool
9630 {
9637 "determining that expression is always "
9639 WARN_STRICT_OVERFLOW_MISC);
9641 }
9643 /* Fold a binary expression of code CODE and type TYPE with operands
9644 OP0 and OP1. LOC is the location of the resulting expression.
9645 Return the folded expression if folding is successful. Otherwise,
9646 return NULL_TREE. */
9648 tree
9651 {
9666 /* Strip any conversions that don't change the mode. This is
9667 safe for every expression, except for a comparison expression
9668 because its signedness is derived from its operands. So, in
9669 the latter case, only strip conversions that don't change the
9670 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9671 preserved.
9673 Note that this is done as an internal manipulation within the
9674 constant folder, in order to find the simplest representation
9675 of the arguments so that their form can be studied. In any
9676 cases, the appropriate type conversions should be put back in
9677 the tree that will get out of the constant folder. */
9680 {
9683 }
9684 else
9685 {
9688 }
9690 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9691 constant but we can't do arithmetic on them. */
9699 {
9701 {
9702 /* Make sure type and arg0 have the same saturating flag. */
9706 }
9709 else
9713 {
9717 }
9718 }
9720 /* If this is a commutative operation, and ARG0 is a constant, move it
9721 to ARG1 to reduce the number of tests below. */
9726 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9727 to ARG1 to reduce the number of tests below. */
9736 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9738 First check for cases where an arithmetic operation is applied to a
9739 compound, conditional, or comparison operation. Push the arithmetic
9740 operation inside the compound or conditional to see if any folding
9741 can then be done. Convert comparison to conditional for this purpose.
9742 The also optimizes non-constant cases that used to be done in
9743 expand_expr.
9745 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9746 one of the operands is a comparison and the other is a comparison, a
9747 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9748 code below would make the expression more complex. Change it to a
9749 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9750 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9763 {
9767 boolean_type_node,
9775 }
9779 {
9781 {
9786 tem);
9787 }
9790 {
9795 tem);
9796 }
9801 {
9807 }
9812 {
9818 }
9819 }
9822 {
9824 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9827 {
9833 }
9835 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9838 {
9839 tree base;
9840 HOST_WIDE_INT coffset;
9849 }
9854 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9860 arg1),
9862 arg0)));
9864 /* PTR_CST +p CST -> CST1 */
9873 {
9874 /* X + (X / CST) * -CST is X % CST. */
9879 {
9888 cst0));
9889 }
9890 }
9892 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9893 one. Make sure the type is not saturating and has the signedness of
9894 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9895 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9902 {
9906 }
9909 {
9910 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9911 with a constant, and the two constants have no bits in common,
9912 we should treat this as a BIT_IOR_EXPR since this may produce more
9913 simplifications. */
9920 {
9923 }
9925 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9926 (plus (plus (mult) (mult)) (foo)) so that we can
9927 take advantage of the factoring cases below. */
9935 {
9941 else
9954 parg0),
9956 marg)),
9960 return
9966 parg1)));
9967 }
9968 }
9969 else
9970 {
9971 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9972 to __complex__ ( x, y ). This is not the same for SNaNs or
9973 if signed zeros are involved. */
9977 {
9984 {
9988 {
9994 }
9996 {
10002 }
10003 }
10004 }
10012 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10013 We associate floats only if the user has specified
10014 -fassociative-math. */
10018 {
10023 {
10024 tree tree0;
10027 }
10028 }
10029 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10030 We associate floats only if the user has specified
10031 -fassociative-math. */
10035 {
10040 {
10041 tree tree0;
10044 }
10045 }
10046 }
10048 bit_rotate:
10049 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10050 is a rotate of A by C1 bits. */
10051 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10052 is a rotate of A by B bits. */
10053 {
10055 tree rtype;
10064 /* Only create rotates in complete modes. Other cases are not
10065 expanded properly. */
10068 {
10082 {
10088 }
10090 {
10098 element_precision
10102 return
10105 ? LROTATE_EXPR
10109 }
10111 {
10119 element_precision
10123 return fold_convert_loc
10126 ? LROTATE_EXPR
10130 }
10131 }
10132 }
10134 associate:
10135 /* In most languages, can't associate operations on floats through
10136 parentheses. Rather than remember where the parentheses were, we
10137 don't associate floats at all, unless the user has specified
10138 -fassociative-math.
10139 And, we need to make sure type is not saturating. */
10143 {
10149 /* Split both trees into variables, constants, and literals. Then
10150 associate each group together, the constants with literals,
10151 then the result with variables. This increases the chances of
10152 literals being recombined later and of generating relocatable
10153 expressions for the sum of a constant and literal. */
10158 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10162 /* With undefined overflow prefer doing association in a type
10163 which wraps on overflow, if that is one of the operand types. */
10166 {
10174 }
10176 /* With undefined overflow we can only associate constants with one
10177 variable, and constants whose association doesn't overflow. */
10180 {
10182 {
10200 /* The only case we can still associate with two variables
10201 is if they are the same, modulo negation and bit-pattern
10202 preserving conversions. */
10205 }
10206 }
10208 /* Only do something if we found more than two objects. Otherwise,
10209 nothing has changed and we risk infinite recursion. */
10215 {
10227 /* Preserve the MINUS_EXPR if the negative part of the literal is
10228 greater than the positive part. Otherwise, the multiplicative
10229 folding code (i.e extract_muldiv) may be fooled in case
10230 unsigned constants are subtracted, like in the following
10231 example: ((X*2 + 4) - 8U)/2. */
10233 {
10237 {
10241 }
10242 else
10243 {
10247 }
10248 }
10250 /* Don't introduce overflows through reassociation. */
10257 {
10259 return
10263 else
10264 {
10267 return
10271 }
10272 }
10275 return
10278 }
10279 }
10284 /* Pointer simplifications for subtraction, simple reassociations. */
10286 {
10287 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10290 {
10300 }
10301 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10303 {
10310 }
10311 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10312 simplifies. */
10314 {
10321 arg10);
10324 }
10325 }
10326 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10335 /* Convert -A - 1 to ~A. */
10343 /* Convert -1 - A to ~A. */
10349 /* X - (X / Y) * Y is X % Y. */
10357 return
10363 {
10364 /* Fold A - (A & B) into ~B & A. */
10367 {
10369 {
10376 }
10378 {
10385 }
10386 }
10388 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10389 any power of 2 minus 1. */
10394 {
10400 {
10404 }
10405 }
10406 }
10408 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10409 __complex__ ( x, -y ). This is not the same for SNaNs or if
10410 signed zeros are involved. */
10414 {
10421 {
10425 {
10427 arg1r ? arg1r
10432 }
10434 {
10438 arg1i ? arg1i
10441 }
10442 }
10443 }
10445 /* A - B -> A + (-B) if B is easily negatable. */
10449 /* Avoid this transformation if B is a positive REAL_CST. */
10458 /* Try folding difference of addresses. */
10459 {
10460 HOST_WIDE_INT diff;
10466 }
10468 /* Fold &a[i] - &a[j] to i-j. */
10473 {
10479 }
10482 && flag_unsafe_math_optimizations
10488 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10489 one. Make sure the type is not saturating and has the signedness of
10490 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10491 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10498 {
10502 }
10507 /* (-A) * (-B) -> A * B */
10522 {
10523 /* Transform x * -C into -x * C if x is easily negatable. */
10532 tem);
10534 /* (a * (1 << b)) is (a << b) */
10544 /* (A + A) * C -> A * 2 * C */
10556 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10557 sign-changing only. */
10567 {
10570 "occur when simplifying "
10572 WARN_STRICT_OVERFLOW_MISC);
10574 }
10576 /* Optimize z * conj(z) for integer complex numbers. */
10583 }
10584 else
10585 {
10586 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10587 the result for floating point types due to rounding so it is applied
10588 only if -fassociative-math was specify. */
10593 {
10595 arg1);
10599 }
10601 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10603 {
10606 {
10609 }
10610 }
10612 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10613 This is not the same for NaNs or if signed zeros are
10614 involved. */
10620 {
10623 return
10629 return
10634 }
10636 /* Optimize z * conj(z) for floating point complex numbers.
10637 Guarded by flag_unsafe_math_optimizations as non-finite
10638 imaginary components don't produce scalar results. */
10649 {
10653 /* Optimizations of root(...)*root(...). */
10655 {
10660 /* Optimize sqrt(x)*sqrt(x) as x. */
10666 /* Optimize root(x)*root(y) as root(x*y). */
10670 }
10672 /* Optimize expN(x)*expN(y) as expN(x+y). */
10674 {
10680 }
10682 /* Optimizations of pow(...)*pow(...). */
10686 {
10692 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10694 {
10699 }
10701 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10703 {
10708 }
10709 }
10711 /* Optimize tan(x)*cos(x) as sin(x). */
10720 {
10726 }
10728 /* Optimize x*pow(x,c) as pow(x,c+1). */
10732 {
10738 {
10740 REAL_VALUE_TYPE c;
10741 tree arg;
10747 }
10748 }
10750 /* Optimize pow(x,c)*x as pow(x,c+1). */
10754 {
10760 {
10762 REAL_VALUE_TYPE c;
10763 tree arg;
10769 }
10770 }
10772 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10774 && optimize
10776 {
10780 {
10783 }
10784 }
10785 }
10786 }
10790 bit_ior:
10791 /* ~X | X is -1. */
10794 {
10798 }
10800 /* X | ~X is -1. */
10803 {
10807 }
10809 /* Canonicalize (X & C1) | C2. */
10813 {
10818 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10826 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10831 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10832 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10833 mode which allows further optimizations. */
10838 {
10842 {
10845 }
10846 }
10853 c3)),
10854 arg1);
10855 }
10857 /* (X & ~Y) | (~X & Y) is X ^ Y */
10860 {
10877 }
10883 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10885 This results in more efficient code for machines without a NAND
10886 instruction. Combine will canonicalize to the first form
10887 which will allow use of NAND instructions provided by the
10888 backend if they exist. */
10891 {
10892 return
10899 }
10901 /* See if this can be simplified into a rotate first. If that
10902 is unsuccessful continue in the association code. */
10906 /* ~X ^ X is -1. */
10909 {
10913 }
10915 /* X ^ ~X is -1. */
10918 {
10922 }
10924 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10925 with a constant, and the two constants have no bits in common,
10926 we should treat this as a BIT_IOR_EXPR since this may produce more
10927 simplifications. */
10934 {
10937 }
10939 /* (X | Y) ^ X -> Y & ~ X*/
10942 {
10945 arg1);
10950 }
10952 /* (Y | X) ^ X -> Y & ~ X*/
10955 {
10958 arg1);
10963 }
10965 /* X ^ (X | Y) -> Y & ~ X*/
10968 {
10971 arg0);
10976 }
10978 /* X ^ (Y | X) -> Y & ~ X*/
10981 {
10984 arg0);
10989 }
10991 /* Convert ~X ^ ~Y to X ^ Y. */
11000 /* Convert ~X ^ C to X ^ ~C. */
11008 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11016 /* Fold (X & Y) ^ Y as ~X & Y. */
11019 {
11024 }
11025 /* Fold (X & Y) ^ X as ~Y & X. */
11029 {
11034 }
11035 /* Fold X ^ (X & Y) as X & ~Y. */
11038 {
11043 }
11044 /* Fold X ^ (Y & X) as ~Y & X. */
11048 {
11053 }
11055 /* See if this can be simplified into a rotate first. If that
11056 is unsuccessful continue in the association code. */
11060 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11068 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11076 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11081 {
11082 tree tem2;
11089 }
11090 /* Fold ~X & 1 as (X & 1) == 0. */
11094 {
11095 tree tem2;
11102 }
11103 /* Fold !X & 1 as X == 0. */
11106 {
11110 }
11112 /* Fold (X ^ Y) & Y as ~X & Y. */
11115 {
11120 }
11121 /* Fold (X ^ Y) & X as ~Y & X. */
11125 {
11130 }
11131 /* Fold X & (X ^ Y) as X & ~Y. */
11134 {
11139 }
11140 /* Fold X & (Y ^ X) as ~Y & X. */
11144 {
11149 }
11151 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11152 multiple of 1 << CST. */
11154 {
11161 }
11163 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11164 bits from CST2. */
11168 {
11176 {
11177 /* Avoid the transform if arg1 is a mask of some
11178 mode which allows further optimizations. */
11185 }
11186 }
11188 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11189 ((A & N) + B) & M -> (A + B) & M
11190 Similarly if (N & M) == 0,
11191 ((A | N) + B) & M -> (A + B) & M
11192 and for - instead of + (or unary - instead of +)
11193 and/or ^ instead of |.
11194 If B is constant and (B & M) == 0, fold into A & M. */
11196 {
11205 {
11208 wide_int cst0;
11210 /* Now we know that arg0 is (C + D) or (C - D) or
11211 -C and arg1 (M) is == (1LL << cst) - 1.
11212 Store C into PMOP[0] and D into PMOP[1]. */
11216 {
11219 }
11226 {
11236 {
11239 }
11242 /* If C or D is of the form (A & N) where
11243 (N & M) == M, or of the form (A | N) or
11244 (A ^ N) where (N & M) == 0, replace it with A. */
11248 /* If C or D is a N where (N & M) == 0, it can be
11249 omitted (assumed 0). */
11257 }
11259 /* Only build anything new if we optimized one or both arguments
11260 above. */
11264 {
11267 {
11268 /* Perform the operations in a type that has defined
11269 overflow behavior. */
11275 }
11280 {
11288 else
11290 }
11293 else
11296 /* TEM is now the new binary +, - or unary - replacement. */
11300 }
11301 }
11302 }
11307 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11310 {
11315 return
11317 }
11319 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11321 This results in more efficient code for machines without a NOR
11322 instruction. Combine will canonicalize to the first form
11323 which will allow use of NOR instructions provided by the
11324 backend if they exist. */
11327 {
11334 }
11336 /* If arg0 is derived from the address of an object or function, we may
11337 be able to fold this expression using the object or function's
11338 alignment. */
11340 {
11347 /* This works because modulus is a power of 2. If this weren't the
11348 case, we'd have to replace it by its greatest power-of-2
11349 divisor: modulus & -modulus. */
11352 }
11354 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11355 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11356 if the new mask might be further optimized. */
11365 {
11376 {
11379 /* See if more bits can be proven as zero because of
11380 zero extension. */
11383 {
11388 {
11390 /* See if we can shorten the right shift. */
11393 /* Otherwise X >> C1 is all zeros, so we'll optimize
11394 it into (X, 0) later on by making sure zerobits
11395 is all ones. */
11396 }
11397 }
11400 {
11403 }
11404 /* For arithmetic shift if sign bit could be set, zerobits
11405 can contain actually sign bits, so no transformation is
11406 possible, unless MASK masks them all away. In that
11407 case the shift needs to be converted into logical shift. */
11410 {
11413 else
11415 }
11416 }
11418 /* ((X << 16) & 0xff00) is (X, 0). */
11425 {
11426 /* Only do the transformation if NEWMASK is some integer
11427 mode's mask. */
11434 {
11435 tree newmaskt;
11438 {
11444 }
11445 else
11450 }
11451 }
11452 }
11457 /* Don't touch a floating-point divide by zero unless the mode
11458 of the constant can represent infinity. */
11464 /* (-A) / (-B) -> A / B */
11474 /* Convert A/B/C to A/(B*C). */
11481 /* Convert A/(B/C) to (A/B)*C. */
11489 /* Convert C1/(X*C2) into (C1/C2)/X. */
11494 {
11500 }
11503 {
11507 /* Optimize sin(x)/cos(x) as tan(x). */
11513 {
11518 }
11520 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11526 {
11530 {
11535 }
11536 }
11538 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11539 NaNs or Infinities. */
11543 {
11550 {
11555 }
11556 }
11558 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11559 NaNs or Infinities. */
11563 {
11570 {
11574 {
11578 tmp);
11579 }
11580 }
11581 }
11583 /* Optimize pow(x,c)/x as pow(x,c-1). */
11587 {
11593 {
11595 REAL_VALUE_TYPE c;
11596 tree arg;
11602 }
11603 }
11605 /* Optimize a/root(b/c) into a*root(c/b). */
11607 {
11611 {
11620 }
11621 }
11623 /* Optimize x/expN(y) into x*expN(-y). */
11625 {
11632 }
11634 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11638 {
11646 }
11647 }
11651 /* Optimize (X & (-A)) / A where A is a power of 2,
11652 to X >> log2(A) */
11656 {
11664 }
11665 }
11667 /* Fall through */
11670 /* Simplify A / (B << N) where A and B are positive and B is
11671 a power of 2, to A >> (N + log2(B)). */
11676 {
11679 {
11687 WARN_STRICT_OVERFLOW_MISC);
11693 }
11694 }
11696 /* Fall through */
11704 /* Convert -A / -B to A / B when the type is signed and overflow is
11705 undefined. */
11709 {
11712 "when distributing negation across "
11714 WARN_STRICT_OVERFLOW_MISC);
11720 }
11724 {
11727 "when distributing negation across "
11729 WARN_STRICT_OVERFLOW_MISC);
11735 }
11737 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11738 operation, EXACT_DIV_EXPR.
11740 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11741 At one time others generated faster code, it's not clear if they do
11742 after the last round to changes to the DIV code in expmed.c. */
11751 {
11755 WARN_STRICT_OVERFLOW_MISC);
11757 }
11765 /* X % -Y is the same as X % Y. */
11778 {
11782 WARN_STRICT_OVERFLOW_MISC);
11784 }
11786 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11787 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11791 {
11793 /* Also optimize A % (C << N) where C is a power of 2,
11794 to A & ((C << N) - 1). */
11799 {
11800 tree mask
11805 "occur when simplifying "
11807 WARN_STRICT_OVERFLOW_MISC);
11811 }
11812 }
11820 /* Since negative shift count is not well-defined,
11821 don't try to compute it in the compiler. */
11827 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11832 {
11836 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11837 being well defined. */
11839 {
11845 else
11847 }
11851 }
11853 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11854 into x & ((unsigned)-1 >> c) for unsigned types. */
11862 {
11865 tree lshift;
11866 tree arg00;
11869 {
11876 }
11877 }
11879 /* If we have a rotate of a bit operation with the rotate count and
11880 the second operand of the bit operation both constant,
11881 permute the two operations. */
11893 /* Two consecutive rotates adding up to the some integer
11894 multiple of the precision of the type can be ignored. */
11902 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11903 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11904 if the latter can be further optimized. */
11909 {
11913 arg1);
11917 arg1);
11921 }
11938 /* Note that the operands of this must be ints
11939 and their values must be 0 or 1.
11940 ("true" is a fixed value perhaps depending on the language.) */
11941 /* If first arg is constant zero, return it. */
11945 /* If either arg is constant true, drop it. */
11949 /* Preserve sequence points. */
11952 /* If second arg is constant zero, result is zero, but first arg
11953 must be evaluated. */
11956 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11957 case will be handled here. */
11961 /* !X && X is always false. */
11965 /* X && !X is always false. */
11970 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
11971 means A >= Y && A != MAX, but in this case we know that
11972 A < X <= MAX. */
11976 {
11984 }
11993 /* Note that the operands of this must be ints
11994 and their values must be 0 or true.
11995 ("true" is a fixed value perhaps depending on the language.) */
11996 /* If first arg is constant true, return it. */
12000 /* If either arg is constant zero, drop it. */
12004 /* Preserve sequence points. */
12007 /* If second arg is constant true, result is true, but we must
12008 evaluate first arg. */
12011 /* Likewise for first arg, but note this only occurs here for
12012 TRUTH_OR_EXPR. */
12016 /* !X || X is always true. */
12020 /* X || !X is always true. */
12025 /* (X && !Y) || (!X && Y) is X ^ Y */
12028 {
12045 }
12054 /* If the second arg is constant zero, drop it. */
12057 /* If the second arg is constant true, this is a logical inversion. */
12059 {
12062 }
12063 /* Identical arguments cancel to zero. */
12067 /* !X ^ X is always true. */
12072 /* X ^ !X is always true. */
12088 /* bool_var != 0 becomes bool_var. */
12093 /* bool_var == 1 becomes bool_var. */
12098 /* bool_var != 1 becomes !bool_var. */
12105 /* bool_var == 0 becomes !bool_var. */
12112 /* !exp != 0 becomes !exp */
12117 /* If this is an equality comparison of the address of two non-weak,
12118 unaliased symbols neither of which are extern (since we do not
12119 have access to attributes for externs), then we know the result. */
12132 {
12133 /* We know that we're looking at the address of two
12134 non-weak, unaliased, static _DECL nodes.
12136 It is both wasteful and incorrect to call operand_equal_p
12137 to compare the two ADDR_EXPR nodes. It is wasteful in that
12138 all we need to do is test pointer equality for the arguments
12139 to the two ADDR_EXPR nodes. It is incorrect to use
12140 operand_equal_p as that function is NOT equivalent to a
12141 C equality test. It can in fact return false for two
12142 objects which would test as equal using the C equality
12143 operator. */
12147 type);
12148 }
12150 /* Similarly for a NEGATE_EXPR. */
12154 arg1)))
12159 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12167 arg1),
12170 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12179 {
12183 val,
12187 }
12189 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12196 {
12198 code == NE_EXPR
12201 }
12203 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12208 /* If this is an EQ or NE comparison with zero and ARG0 is
12209 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12210 two operations, but the latter can be done in one less insn
12211 on machines that have only two-operand insns or on which a
12212 constant cannot be the first operand. */
12215 {
12220 {
12227 arg1);
12228 }
12231 {
12238 arg1);
12239 }
12240 }
12242 /* If this is an NE or EQ comparison of zero against the result of a
12243 signed MOD operation whose second operand is a power of 2, make
12244 the MOD operation unsigned since it is simpler and equivalent. */
12252 {
12262 }
12264 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12265 C1 is a valid shift constant, and C2 is a power of two, i.e.
12266 a single bit. */
12270 == INTEGER_CST
12273 {
12278 /* Check for a valid shift count. */
12280 {
12284 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12285 can be rewritten as (X & (C2 << C1)) != 0. */
12287 {
12292 }
12293 /* Otherwise, for signed (arithmetic) shifts,
12294 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12295 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12299 /* Otherwise, of unsigned (logical) shifts,
12300 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12301 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12302 else
12306 arg000);
12307 }
12308 }
12310 /* If we have (A & C) == C where C is a power of 2, convert this into
12311 (A & C) != 0. Similarly for NE_EXPR. */
12317 integer_zero_node));
12319 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12320 bit, then fold the expression into A < 0 or A >= 0. */
12325 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12326 Similarly for NE_EXPR. */
12330 {
12334 tree dandnotc
12337 notc);
12341 }
12343 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12344 Similarly for NE_EXPR. */
12348 {
12350 tree candnotd
12357 }
12359 /* If this is a comparison of a field, we may be able to simplify it. */
12362 /* Handle the constant case even without -O
12363 to make sure the warnings are given. */
12365 {
12369 }
12371 /* Optimize comparisons of strlen vs zero to a compare of the
12372 first character of the string vs zero. To wit,
12373 strlen(ptr) == 0 => *ptr == 0
12374 strlen(ptr) != 0 => *ptr != 0
12375 Other cases should reduce to one of these two (or a constant)
12376 due to the return value of strlen being unsigned. */
12379 {
12387 {
12392 }
12393 }
12395 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12396 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12400 {
12405 {
12407 {
12410 }
12413 }
12414 }
12416 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12422 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12427 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12434 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12442 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12443 (X & C) == 0 when C is a single bit. */
12448 {
12455 arg1));
12456 }
12458 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12459 constant C is a power of two, i.e. a single bit. */
12466 {
12470 }
12472 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12473 when is C is a power of two, i.e. a single bit. */
12480 {
12486 }
12490 {
12493 }
12495 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12503 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12506 {
12519 arg01),
12528 arg01),
12537 arg00),
12546 arg00),
12548 }
12552 {
12559 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12560 operand_equal_p guarantees no side-effects so we don't need
12561 to use omit_one_operand on Z. */
12565 arg10));
12569 arg11));
12573 arg10));
12577 arg11));
12579 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12582 {
12588 }
12589 }
12591 /* Attempt to simplify equality/inequality comparisons of complex
12592 values. Only lower the comparison if the result is known or
12593 can be simplified to a single scalar comparison. */
12598 {
12603 {
12606 }
12607 else
12608 {
12611 }
12614 {
12617 }
12618 else
12619 {
12622 }
12626 {
12628 {
12633 }
12634 else
12635 {
12640 }
12641 }
12645 {
12647 {
12652 }
12653 else
12654 {
12659 }
12660 }
12661 }
12673 /* Transform comparisons of the form X +- C CMP X. */
12680 {
12687 else
12690 /* (X - c) > X becomes false. */
12694 {
12698 "occur when assuming that (X - c) > X "
12700 WARN_STRICT_OVERFLOW_ALL);
12702 }
12704 /* Likewise (X + c) < X becomes false. */
12708 {
12712 "occur when assuming that "
12714 WARN_STRICT_OVERFLOW_ALL);
12716 }
12718 /* Convert (X - c) <= X to true. */
12723 {
12727 "occur when assuming that "
12729 WARN_STRICT_OVERFLOW_ALL);
12731 }
12733 /* Convert (X + c) >= X to true. */
12738 {
12742 "occur when assuming that "
12744 WARN_STRICT_OVERFLOW_ALL);
12746 }
12749 {
12750 /* Convert X + c > X and X - c < X to true for integers. */
12754 {
12757 "not occur when assuming that "
12759 WARN_STRICT_OVERFLOW_ALL);
12761 }
12766 {
12769 "not occur when assuming that "
12771 WARN_STRICT_OVERFLOW_ALL);
12773 }
12775 /* Convert X + c <= X and X - c >= X to false for integers. */
12779 {
12782 "not occur when assuming that "
12784 WARN_STRICT_OVERFLOW_ALL);
12786 }
12791 {
12794 "not occur when assuming that "
12796 WARN_STRICT_OVERFLOW_ALL);
12798 }
12799 }
12800 }
12802 /* Comparisons with the highest or lowest possible integer of
12803 the specified precision will have known values. */
12804 {
12810 {
12817 {
12830 /* The GE_EXPR and LT_EXPR cases above are not normally
12831 reached because of previous transformations. */
12835 }
12838 {
12845 arg1);
12851 arg0),
12852 arg1);
12855 }
12858 {
12873 }
12876 {
12883 arg1);
12889 arg0),
12890 arg1);
12893 }
12897 /* We will flip the signedness of the comparison operator
12898 associated with the mode of arg1, so the sign bit is
12899 specified by this mode. Check that arg1 is the signed
12900 max associated with this sign bit. */
12902 /* signed_type does not work on pointer types. */
12904 {
12905 /* The following case also applies to X < signed_max+1
12906 and X >= signed_max+1 because previous transformations. */
12908 {
12914 }
12915 }
12916 }
12917 }
12919 /* If we are comparing an ABS_EXPR with a constant, we can
12920 convert all the cases into explicit comparisons, but they may
12921 well not be faster than doing the ABS and one comparison.
12922 But ABS (X) <= C is a range comparison, which becomes a subtraction
12923 and a comparison, and is probably faster. */
12937 /* Convert ABS_EXPR<x> >= 0 to true. */
12944 {
12947 "when simplifying comparison of "
12949 WARN_STRICT_OVERFLOW_CONDITIONAL);
12952 arg0);
12953 }
12955 /* Convert ABS_EXPR<x> < 0 to false. */
12960 {
12963 "when simplifying comparison of "
12965 WARN_STRICT_OVERFLOW_CONDITIONAL);
12968 arg0);
12969 }
12971 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
12972 and similarly for >= into !=. */
12982 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
12983 otherwise Y might be >= # of bits in X's type and thus e.g.
12984 (unsigned char) (1 << Y) for Y 15 might be 0.
12985 If the cast is widening, then 1 << Y should have unsigned type,
12986 otherwise if Y is number of bits in the signed shift type minus 1,
12987 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
12988 31 might be 0xffffffff80000000. */
12999 {
13005 }
13018 {
13022 }
13024 /* If the first operand is NaN, the result is constant. */
13028 {
13030 ? integer_zero_node
13033 }
13035 /* If the second operand is NaN, the result is constant. */
13039 {
13041 ? integer_zero_node
13044 }
13046 /* Simplify unordered comparison of something with itself. */
13052 && !flag_trapping_math
13056 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13057 {
13069 }
13074 /* When pedantic, a compound expression can be neither an lvalue
13075 nor an integer constant expression. */
13078 /* Don't let (0, 0) be null pointer constant. */
13092 /* An ASSERT_EXPR should never be passed to fold_binary. */
13097 {
13112 {
13118 }
13121 }
13127 {
13152 {
13165 }
13168 }
13173 }
13175 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13176 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13177 of GOTO_EXPR. */
13179 static tree
13181 {
13183 {
13190 /* ... fall through ... */
13194 }
13195 }
13197 /* Return whether the sub-tree ST contains a label which is accessible from
13198 outside the sub-tree. */
13200 static bool
13202 {
13203 return
13205 }
13207 /* Fold a ternary expression of code CODE and type TYPE with operands
13208 OP0, OP1, and OP2. Return the folded expression if folding is
13209 successful. Otherwise, return NULL_TREE. */
13211 tree
13214 {
13215 tree tem;
13222 /* If this is a commutative operation, and OP0 is a constant, move it
13223 to OP1 to reduce the number of tests below. */
13232 /* Strip any conversions that don't change the mode. This is safe
13233 for every expression, except for a comparison expression because
13234 its signedness is derived from its operands. So, in the latter
13235 case, only strip conversions that don't change the signedness.
13237 Note that this is done as an internal manipulation within the
13238 constant folder, in order to find the simplest representation of
13239 the arguments so that their form can be studied. In any cases,
13240 the appropriate type conversions should be put back in the tree
13241 that will get out of the constant folder. */
13243 {
13246 }
13249 {
13252 }
13255 {
13258 }
13261 {
13265 {
13271 }
13276 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13277 so all simple results must be passed through pedantic_non_lvalue. */
13279 {
13282 /* Only optimize constant conditions when the selected branch
13283 has the same type as the COND_EXPR. This avoids optimizing
13284 away "c ? x : throw", where the throw has a void type.
13285 Avoid throwing away that operand which contains label. */
13292 }
13294 {
13299 {
13304 {
13312 }
13316 }
13317 }
13319 /* If we have A op B ? A : C, we may be able to convert this to a
13320 simpler expression, depending on the operation and the values
13321 of B and C. Signed zeros prevent all of these transformations,
13322 for reasons given above each one.
13324 Also try swapping the arguments and inverting the conditional. */
13329 {
13333 }
13337 op2,
13340 {
13344 {
13348 }
13349 }
13351 /* If the second operand is simpler than the third, swap them
13352 since that produces better jump optimization results. */
13355 {
13357 /* See if this can be inverted. If it can't, possibly because
13358 it was a floating-point inequality comparison, don't do
13359 anything. */
13363 }
13365 /* Convert A ? 1 : 0 to simply A. */
13370 /* If we try to convert OP0 to our type, the
13371 call to fold will try to move the conversion inside
13372 a COND, which will recurse. In that case, the COND_EXPR
13373 is probably the best choice, so leave it alone. */
13377 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13378 over COND_EXPR in cases such as floating point comparisons. */
13387 arg0)));
13389 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13394 {
13395 /* sign_bit_p looks through both zero and sign extensions,
13396 but for this optimization only sign extensions are
13397 usable. */
13400 {
13403 {
13406 }
13408 }
13409 /* sign_bit_p only checks ARG1 bits within A's precision.
13410 If <sign bit of A> has wider type than A, bits outside
13411 of A's precision in <sign bit of A> need to be checked.
13412 If they are all 0, this optimization needs to be done
13413 in unsigned A's type, if they are all 1 in signed A's type,
13414 otherwise this can't be done. */
13420 {
13422 tree tem_type;
13435 {
13438 }
13440 {
13443 }
13444 else
13446 }
13449 return
13455 arg1)));
13456 }
13458 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13459 already handled above. */
13464 {
13473 }
13475 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13476 is probably obsolete because the first operand should be a
13477 truth value (that's why we have the two cases above), but let's
13478 leave it in until we can confirm this for all front-ends. */
13490 /* Disable the transformations below for vectors, since
13491 fold_binary_op_with_conditional_arg may undo them immediately,
13492 yielding an infinite loop. */
13496 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13505 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13510 {
13512 /* Only perform transformation if ARG0 is easily inverted. */
13516 ? BIT_IOR_EXPR
13519 arg1);
13520 }
13522 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13527 {
13529 /* Only perform transformation if ARG0 is easily inverted. */
13535 op2);
13536 }
13538 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13550 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13551 of fold_ternary on them. */
13561 {
13571 {
13576 {
13584 }
13586 /* Constructor elements can be subvectors. */
13589 {
13593 }
13595 /* We keep an exact subset of the constructor elements. */
13597 {
13603 {
13607 }
13615 CONSTRUCTOR_ELT
13618 }
13619 /* The bitfield references a single constructor element. */
13621 {
13626 else
13630 }
13631 }
13632 }
13634 /* A bit-field-ref that referenced the full argument can be stripped. */
13640 /* On constants we can use native encode/interpret to constant
13641 fold (nearly) all BIT_FIELD_REFs. */
13645 /* This limitation should not be necessary, we just need to
13646 round this up to mode size. */
13648 /* Need bit-shifting of the buffer to relax the following. */
13650 {
13655 /* ??? We cannot tell native_encode_expr to start at
13656 some random byte only. So limit us to a reasonable amount
13657 of work. */
13659 {
13664 {
13670 }
13671 }
13672 }
13677 /* For integers we can decompose the FMA if possible. */
13689 {
13705 {
13710 /* Make sure that the perm value is in an acceptable
13711 range. */
13720 else
13725 }
13728 {
13733 }
13738 {
13743 }
13749 {
13753 }
13758 /* Some targets are deficient and fail to expand a single
13759 argument permutation while still allowing an equivalent
13760 2-argument version. */
13764 {
13767 }
13770 {
13777 }
13781 }
13787 }
13789 /* Perform constant folding and related simplification of EXPR.
13790 The related simplifications include x*1 => x, x*0 => 0, etc.,
13791 and application of the associative law.
13792 NOP_EXPR conversions may be removed freely (as long as we
13793 are careful not to change the type of the overall expression).
13794 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13795 but we can constant-fold them if they have constant operands. */
13797 #ifdef ENABLE_FOLD_CHECKING
13798 # define fold(x) fold_1 (x)
13800 static
13801 #endif
13802 tree
13804 {
13808 tree tem;
13811 /* Return right away if a constant. */
13815 /* CALL_EXPR-like objects with variable numbers of operands are
13816 treated specially. */
13818 {
13820 {
13823 }
13825 }
13828 {
13833 {
13851 }
13852 }
13855 {
13857 {
13864 {
13869 /* Find a matching index by means of a binary search. */
13871 {
13887 else
13889 }
13890 }
13893 }
13895 /* Return a VECTOR_CST if possible. */
13897 {
13904 tree value;
13907 {
13911 {
13914 }
13915 else
13917 }
13922 }
13930 }
13932 #ifdef ENABLE_FOLD_CHECKING
13933 #undef fold
13940 /* When --enable-checking=fold, compute a digest of expr before
13941 and after actual fold call to see if fold did not accidentally
13942 change original expr. */
13944 tree
13946 {
13947 tree ret;
13967 }
13969 void
13971 {
13982 }
13984 static void
13986 {
13988 }
13990 static void
13993 {
13999 recursive_label:
14009 {
14010 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14014 }
14021 {
14022 /* Allow these fields to be modified. */
14023 tree tmp;
14031 {
14034 }
14035 }
14046 {
14049 {
14064 }
14068 {
14081 }
14098 {
14104 }
14107 {
14109 {
14112 }
14114 }
14125 {
14128 }
14138 }
14139 }
14141 /* Helper function for outputting the checksum of a tree T. When
14142 debugging with gdb, you can "define mynext" to be "next" followed
14143 by "call debug_fold_checksum (op0)", then just trace down till the
14144 outputs differ. */
14146 DEBUG_FUNCTION void
14148 {
14163 }
14165 #endif
14167 /* Fold a unary tree expression with code CODE of type TYPE with an
14168 operand OP0. LOC is the location of the resulting expression.
14169 Return a folded expression if successful. Otherwise, return a tree
14170 expression with code CODE of type TYPE with an operand OP0. */
14172 tree
14175 {
14176 tree tem;
14177 #ifdef ENABLE_FOLD_CHECKING
14186 #endif
14192 #ifdef ENABLE_FOLD_CHECKING
14199 #endif
14201 }
14203 /* Fold a binary tree expression with code CODE of type TYPE with
14204 operands OP0 and OP1. LOC is the location of the resulting
14205 expression. Return a folded expression if successful. Otherwise,
14206 return a tree expression with code CODE of type TYPE with operands
14207 OP0 and OP1. */
14209 tree
14212 MEM_STAT_DECL)
14213 {
14214 tree tem;
14215 #ifdef ENABLE_FOLD_CHECKING
14232 #endif
14238 #ifdef ENABLE_FOLD_CHECKING
14253 #endif
14255 }
14257 /* Fold a ternary tree expression with code CODE of type TYPE with
14258 operands OP0, OP1, and OP2. Return a folded expression if
14259 successful. Otherwise, return a tree expression with code CODE of
14260 type TYPE with operands OP0, OP1, and OP2. */
14262 tree
14265 {
14266 tree tem;
14267 #ifdef ENABLE_FOLD_CHECKING
14291 #endif
14298 #ifdef ENABLE_FOLD_CHECKING
14321 #endif
14323 }
14325 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14326 arguments in ARGARRAY, and a null static chain.
14327 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14328 of type TYPE from the given operands as constructed by build_call_array. */
14330 tree
14333 {
14334 tree tem;
14335 #ifdef ENABLE_FOLD_CHECKING
14354 #endif
14358 #ifdef ENABLE_FOLD_CHECKING
14374 #endif
14376 }
14378 /* Perform constant folding and related simplification of initializer
14379 expression EXPR. These behave identically to "fold_buildN" but ignore
14380 potential run-time traps and exceptions that fold must preserve. */
14382 #define START_FOLD_INIT \
14383 int saved_signaling_nans = flag_signaling_nans;\
14384 int saved_trapping_math = flag_trapping_math;\
14385 int saved_rounding_math = flag_rounding_math;\
14386 int saved_trapv = flag_trapv;\
14387 int saved_folding_initializer = folding_initializer;\
14388 flag_signaling_nans = 0;\
14389 flag_trapping_math = 0;\
14390 flag_rounding_math = 0;\
14391 flag_trapv = 0;\
14392 folding_initializer = 1;
14394 #define END_FOLD_INIT \
14395 flag_signaling_nans = saved_signaling_nans;\
14396 flag_trapping_math = saved_trapping_math;\
14397 flag_rounding_math = saved_rounding_math;\
14398 flag_trapv = saved_trapv;\
14399 folding_initializer = saved_folding_initializer;
14401 tree
14404 {
14405 tree result;
14406 START_FOLD_INIT;
14410 END_FOLD_INIT;
14412 }
14414 tree
14417 {
14418 tree result;
14419 START_FOLD_INIT;
14423 END_FOLD_INIT;
14425 }
14427 tree
14430 {
14431 tree result;
14432 START_FOLD_INIT;
14436 END_FOLD_INIT;
14438 }
14440 #undef START_FOLD_INIT
14441 #undef END_FOLD_INIT
14443 /* Determine if first argument is a multiple of second argument. Return 0 if
14444 it is not, or we cannot easily determined it to be.
14446 An example of the sort of thing we care about (at this point; this routine
14447 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14448 fold cases do now) is discovering that
14450 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14452 is a multiple of
14454 SAVE_EXPR (J * 8)
14456 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14458 This code also handles discovering that
14460 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14462 is a multiple of 8 so we don't have to worry about dealing with a
14463 possible remainder.
14465 Note that we *look* inside a SAVE_EXPR only to determine how it was
14466 calculated; it is not safe for fold to do much of anything else with the
14467 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14468 at run time. For example, the latter example above *cannot* be implemented
14469 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14470 evaluation time of the original SAVE_EXPR is not necessarily the same at
14471 the time the new expression is evaluated. The only optimization of this
14472 sort that would be valid is changing
14474 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14476 divided by 8 to
14478 SAVE_EXPR (I) * SAVE_EXPR (J)
14480 (where the same SAVE_EXPR (J) is used in the original and the
14481 transformed version). */
14483 int
14485 {
14493 {
14495 /* Bitwise and provides a power of two multiple. If the mask is
14496 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14499 /* FALLTHRU */
14512 {
14516 /* const_binop may not detect overflow correctly,
14517 so check for it explicitly here. */
14521 size_one_node,
14522 op1)))
14525 }
14529 /* Can't handle conversions from non-integral or wider integral type. */
14535 /* .. fall through ... */
14552 SIGNED);
14556 }
14557 }
14559 /* Return true if CODE or TYPE is known to be non-negative. */
14561 static bool
14563 {
14566 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14567 have a signed:1 type (where the value is -1 and 0). */
14570 }
14572 /* Return true if (CODE OP0) is known to be non-negative. If the return
14573 value is based on the assumption that signed overflow is undefined,
14574 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14575 *STRICT_OVERFLOW_P. */
14577 bool
14580 {
14585 {
14587 /* We can't return 1 if flag_wrapv is set because
14588 ABS_EXPR<INT_MIN> = INT_MIN. */
14592 {
14595 }
14602 strict_overflow_p);
14604 CASE_CONVERT:
14605 {
14610 {
14613 strict_overflow_p);
14615 {
14619 strict_overflow_p);
14620 }
14621 }
14623 {
14626 strict_overflow_p);
14630 }
14631 }
14636 }
14638 /* We don't know sign of `t', so be conservative and return false. */
14640 }
14642 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14643 value is based on the assumption that signed overflow is undefined,
14644 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14645 *STRICT_OVERFLOW_P. */
14647 bool
14650 {
14655 {
14660 strict_overflow_p)
14662 strict_overflow_p));
14664 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14665 both unsigned and at least 2 bits shorter than the result. */
14669 {
14674 {
14678 }
14679 }
14684 {
14685 /* x * x is always non-negative for floating point x
14686 or without overflow. */
14690 {
14694 }
14695 }
14697 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14698 both unsigned and their total bits is shorter than the result. */
14702 {
14721 {
14731 }
14732 }
14738 strict_overflow_p)
14740 strict_overflow_p));
14751 strict_overflow_p)
14753 strict_overflow_p));
14760 strict_overflow_p);
14763 }
14765 /* We don't know sign of `t', so be conservative and return false. */
14767 }
14769 /* Return true if T is known to be non-negative. If the return
14770 value is based on the assumption that signed overflow is undefined,
14771 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14772 *STRICT_OVERFLOW_P. */
14774 bool
14776 {
14781 {
14793 strict_overflow_p)
14795 strict_overflow_p));
14799 }
14800 /* We don't know sign of `t', so be conservative and return false. */
14802 }
14804 /* Return true if T is known to be non-negative. If the return
14805 value is based on the assumption that signed overflow is undefined,
14806 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14807 *STRICT_OVERFLOW_P. */
14809 bool
14812 {
14815 {
14835 /* Always true. */
14839 /* sqrt(-0.0) is -0.0. */
14843 strict_overflow_p);
14880 /* True if the 1st argument is nonnegative. */
14882 strict_overflow_p);
14885 /* True if the 1st OR 2nd arguments are nonnegative. */
14887 strict_overflow_p)
14889 strict_overflow_p)));
14892 /* True if the 1st AND 2nd arguments are nonnegative. */
14894 strict_overflow_p)
14896 strict_overflow_p)));
14899 /* True if the 2nd argument is nonnegative. */
14901 strict_overflow_p);
14904 /* True if the 1st argument is nonnegative or the second
14905 argument is an even integer. */
14910 strict_overflow_p);
14913 /* True if the 1st argument is nonnegative or the second
14914 argument is an even integer valued real. */
14916 {
14917 REAL_VALUE_TYPE c;
14918 HOST_WIDE_INT n;
14923 {
14924 REAL_VALUE_TYPE cint;
14928 }
14929 }
14931 strict_overflow_p);
14935 }
14937 type);
14938 }
14940 /* Return true if T is known to be non-negative. If the return
14941 value is based on the assumption that signed overflow is undefined,
14942 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14943 *STRICT_OVERFLOW_P. */
14945 static bool
14947 {
14953 {
14955 {
14959 /* If the initializer is non-void, then it's a normal expression
14960 that will be assigned to the slot. */
14964 /* Otherwise, the initializer sets the slot in some way. One common
14965 way is an assignment statement at the end of the initializer. */
14967 {
14975 else
14977 }
14981 strict_overflow_p);
14984 }
14987 {
14993 arg0,
14994 arg1,
14995 strict_overflow_p);
14996 }
15000 strict_overflow_p);
15003 strict_overflow_p);
15006 strict_overflow_p);
15011 }
15013 /* We don't know sign of `t', so be conservative and return false. */
15015 }
15017 /* Return true if T is known to be non-negative. If the return
15018 value is based on the assumption that signed overflow is undefined,
15019 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15020 *STRICT_OVERFLOW_P. */
15022 bool
15024 {
15031 {
15038 strict_overflow_p);
15044 strict_overflow_p);
15053 }
15056 {
15064 strict_overflow_p);
15069 strict_overflow_p);
15082 }
15083 }
15085 /* Return true if `t' is known to be non-negative. Handle warnings
15086 about undefined signed overflow. */
15088 bool
15090 {
15097 "determining that expression is always "
15099 WARN_STRICT_OVERFLOW_MISC);
15101 }
15104 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15105 For floating point we further ensure that T is not denormal.
15106 Similar logic is present in nonzero_address in rtlanal.h.
15108 If the return value is based on the assumption that signed overflow
15109 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15110 change *STRICT_OVERFLOW_P. */
15112 bool
15115 {
15117 {
15120 strict_overflow_p);
15123 {
15129 strict_overflow_p));
15130 }
15135 strict_overflow_p);
15139 }
15142 }
15144 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15145 For floating point we further ensure that T is not denormal.
15146 Similar logic is present in nonzero_address in rtlanal.h.
15148 If the return value is based on the assumption that signed overflow
15149 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15150 change *STRICT_OVERFLOW_P. */
15152 bool
15154 tree type,
15155 tree op0,
15157 {
15160 {
15164 {
15165 /* With the presence of negative values it is hard
15166 to say something. */
15173 /* One of operands must be positive and the other non-negative. */
15174 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15175 overflows, on a twos-complement machine the sum of two
15176 nonnegative numbers can never be zero. */
15178 strict_overflow_p)
15180 strict_overflow_p));
15181 }
15186 {
15188 strict_overflow_p)
15190 strict_overflow_p))
15191 {
15194 }
15195 }
15204 {
15207 }
15214 {
15218 /* When both operands are nonzero, then MAX must be too. */
15220 strict_overflow_p))
15223 /* MAX where operand 0 is positive is positive. */
15225 strict_overflow_p);
15226 }
15227 /* MAX where operand 1 is positive is positive. */
15232 {
15236 }
15241 strict_overflow_p)
15243 strict_overflow_p));
15247 }
15250 }
15252 /* Return true when T is an address and is known to be nonzero.
15253 For floating point we further ensure that T is not denormal.
15254 Similar logic is present in nonzero_address in rtlanal.h.
15256 If the return value is based on the assumption that signed overflow
15257 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15258 change *STRICT_OVERFLOW_P. */
15260 bool
15262 {
15265 {
15270 {
15279 /* For objects in symbol table check if we know they are non-zero.
15280 Don't do anything for variables and functions before symtab is built;
15281 it is quite possible that they will be declared weak later. */
15283 {
15289 else
15291 }
15293 /* Function local objects are never NULL. */
15300 /* Constants are never weak. */
15305 }
15313 {
15317 }
15322 }
15324 }
15326 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15327 attempt to fold the expression to a constant without modifying TYPE,
15328 OP0 or OP1.
15330 If the expression could be simplified to a constant, then return
15331 the constant. If the expression would not be simplified to a
15332 constant, then return NULL_TREE. */
15334 tree
15336 {
15339 }
15341 /* Given the components of a unary expression CODE, TYPE and OP0,
15342 attempt to fold the expression to a constant without modifying
15343 TYPE or OP0.
15345 If the expression could be simplified to a constant, then return
15346 the constant. If the expression would not be simplified to a
15347 constant, then return NULL_TREE. */
15349 tree
15351 {
15354 }
15356 /* If EXP represents referencing an element in a constant string
15357 (either via pointer arithmetic or array indexing), return the
15358 tree representing the value accessed, otherwise return NULL. */
15360 tree
15362 {
15366 {
15368 tree index;
15369 tree string;
15374 else
15375 {
15379 /* Optimize the special-case of a zero lower bound.
15381 We convert the low_bound to sizetype to avoid some problems
15382 with constant folding. (E.g. suppose the lower bound is 1,
15383 and its mode is QI. Without the conversion,l (ARRAY
15384 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15385 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15391 }
15404 }
15406 }
15408 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15409 an integer constant, real, or fixed-point constant.
15411 TYPE is the type of the result. */
15413 static tree
15415 {
15419 {
15421 {
15428 }
15435 {
15436 FIXED_VALUE_TYPE f;
15441 /* Propagate overflow flags. */
15445 }
15449 }
15452 }
15454 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15455 an integer constant or real constant.
15457 TYPE is the type of the result. */
15459 tree
15461 {
15465 {
15467 {
15468 /* If the value is unsigned or non-negative, then the absolute value
15469 is the same as the ordinary value. */
15473 /* If the value is negative, then the absolute value is
15474 its negation. */
15475 else
15476 {
15481 }
15482 }
15488 else
15494 }
15497 }
15499 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15500 constant. TYPE is the type of the result. */
15502 static tree
15504 {
15508 }
15510 /* Given CODE, a relational operator, the target type, TYPE and two
15511 constant operands OP0 and OP1, return the result of the
15512 relational operation. If the result is not a compile time
15513 constant, then return NULL_TREE. */
15515 static tree
15517 {
15520 /* From here on, the only cases we handle are when the result is
15521 known to be a constant. */
15524 {
15528 /* Handle the cases where either operand is a NaN. */
15530 {
15532 {
15560 }
15563 }
15566 }
15569 {
15573 }
15575 /* Handle equality/inequality of complex constants. */
15577 {
15588 else
15590 }
15593 {
15600 {
15612 }
15615 }
15617 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15619 To compute GT, swap the arguments and do LT.
15620 To compute GE, do LT and invert the result.
15621 To compute LE, swap the arguments, do LT and invert the result.
15622 To compute NE, do EQ and invert the result.
15624 Therefore, the code below must handle only EQ and LT. */
15627 {
15632 }
15634 /* Note that it is safe to invert for real values here because we
15635 have already handled the one case that it matters. */
15639 {
15642 }
15644 /* Compute a result for LT or EQ if args permit;
15645 Otherwise return T. */
15647 {
15650 else
15652 }
15653 else
15659 }
15661 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15662 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15663 itself. */
15665 tree
15667 {
15668 /* If the expression does not have side effects then we don't have to wrap
15669 it with a cleanup point expression. */
15673 /* If the expression is a return, check to see if the expression inside the
15674 return has no side effects or the right hand side of the modify expression
15675 inside the return. If either don't have side effects set we don't need to
15676 wrap the expression in a cleanup point expression. Note we don't check the
15677 left hand side of the modify because it should always be a return decl. */
15679 {
15686 }
15689 }
15691 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15692 of an indirection through OP0, or NULL_TREE if no simplification is
15693 possible. */
15695 tree
15697 {
15699 tree subtype;
15707 {
15710 /* *&CONST_DECL -> to the value of the const decl. */
15713 /* *&p => p; make sure to handle *&"str"[cst] here. */
15715 {
15719 else
15721 }
15722 /* *(foo *)&fooarray => fooarray[0] */
15725 && (!in_gimple_form
15727 {
15737 }
15738 /* *(foo *)&complexfoo => __real__ complexfoo */
15742 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15745 {
15749 }
15750 }
15754 {
15760 {
15761 tree op00type;
15765 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15768 {
15780 }
15781 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15784 {
15788 }
15789 /* ((foo *)&fooarray)[1] => fooarray[1] */
15792 {
15802 }
15803 }
15804 }
15806 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15809 && (!in_gimple_form
15811 {
15812 tree type_domain;
15822 NULL_TREE);
15823 }
15826 }
15828 /* Builds an expression for an indirection through T, simplifying some
15829 cases. */
15831 tree
15833 {
15841 }
15843 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15845 tree
15847 {
15852 else
15854 }
15856 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15857 whose result is ignored. The type of the returned tree need not be
15858 the same as the original expression. */
15860 tree
15862 {
15868 {
15879 else
15885 {
15901 }
15906 }
15907 }
15909 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15911 tree
15913 {
15919 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15920 have to do anything. Only do this when we are not given a const,
15921 because in that case, this check is more expensive than just
15922 doing it. */
15924 {
15929 }
15931 /* If divisor is a power of two, simplify this to bit manipulation. */
15933 {
15935 {
15949 }
15950 else
15951 {
15952 tree t;
15958 }
15959 }
15960 else
15961 {
15966 }
15969 }
15971 /* Likewise, but round down. */
15973 tree
15975 {
15982 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15983 have to do anything. Only do this when we are not given a const,
15984 because in that case, this check is more expensive than just
15985 doing it. */
15987 {
15992 }
15994 /* If divisor is a power of two, simplify this to bit manipulation. */
15996 {
15997 tree t;
16001 }
16002 else
16003 {
16008 }
16011 }
16013 /* Returns the pointer to the base of the object addressed by EXP and
16014 extracts the information about the offset of the access, storing it
16015 to PBITPOS and POFFSET. */
16017 static tree
16020 {
16021 tree core;
16022 machine_mode mode;
16024 HOST_WIDE_INT bitsize;
16028 {
16033 }
16034 else
16035 {
16039 }
16042 }
16044 /* Returns true if addresses of E1 and E2 differ by a constant, false
16045 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16047 bool
16049 {
16063 {
16073 }
16075 {
16076 /* If only one of the offsets is non-constant, the difference cannot
16077 be a constant. */
16079 }
16080 else
16085 }
16087 /* Simplify the floating point expression EXP when the sign of the
16088 result is not significant. Return NULL_TREE if no simplification
16089 is possible. */
16091 tree
16093 {
16098 {
16134 {
16137 {
16139 /* Strip copysign function call, return the 1st argument. */
16145 /* Strip sign ops from the argument of "odd" math functions. */
16147 {
16151 }
16153 }
16154 }
16159 }
16161 }