| blob | 60aa210496005041d7f8e7bf1920dad9e79b898f |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
89 /* Nonzero if we are folding constants inside an initializer; zero
90 otherwise. */
93 /* The following constants represent a bit based encoding of GCC's
94 comparison operators. This encoding simplifies transformations
95 on relational comparison operators, such as AND and OR. */
113 };
131 HOST_WIDE_INT *,
164 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
165 Otherwise, return LOC. */
167 static location_t
169 {
172 }
174 /* Similar to protected_set_expr_location, but never modify x in place,
175 if location can and needs to be set, unshare it. */
179 {
185 {
188 }
190 }
191 \f
192 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
193 division and returns the quotient. Otherwise returns
194 NULL_TREE. */
196 tree
198 {
199 widest_int quo;
206 }
207 \f
208 /* This is nonzero if we should defer warnings about undefined
209 overflow. This facility exists because these warnings are a
210 special case. The code to estimate loop iterations does not want
211 to issue any warnings, since it works with expressions which do not
212 occur in user code. Various bits of cleanup code call fold(), but
213 only use the result if it has certain characteristics (e.g., is a
214 constant); that code only wants to issue a warning if the result is
215 used. */
219 /* If a warning about undefined overflow is deferred, this is the
220 warning. Note that this may cause us to turn two warnings into
221 one, but that is fine since it is sufficient to only give one
222 warning per expression. */
226 /* If a warning about undefined overflow is deferred, this is the
227 level at which the warning should be emitted. */
231 /* Start deferring overflow warnings. We could use a stack here to
232 permit nested calls, but at present it is not necessary. */
234 void
236 {
238 }
240 /* Stop deferring overflow warnings. If there is a pending warning,
241 and ISSUE is true, then issue the warning if appropriate. STMT is
242 the statement with which the warning should be associated (used for
243 location information); STMT may be NULL. CODE is the level of the
244 warning--a warn_strict_overflow_code value. This function will use
245 the smaller of CODE and the deferred code when deciding whether to
246 issue the warning. CODE may be zero to mean to always use the
247 deferred code. */
249 void
251 {
253 location_t locus;
258 {
264 }
275 /* Use the smallest code level when deciding to issue the
276 warning. */
285 else
288 }
290 /* Stop deferring overflow warnings, ignoring any deferred
291 warnings. */
293 void
295 {
297 }
299 /* Whether we are deferring overflow warnings. */
301 bool
303 {
305 }
307 /* This is called when we fold something based on the fact that signed
308 overflow is undefined. */
310 static void
312 {
314 {
317 {
320 }
321 }
324 }
325 \f
326 /* Return true if the built-in mathematical function specified by CODE
327 is odd, i.e. -f(x) == f(-x). */
329 static bool
331 {
333 {
367 }
369 }
371 /* Check whether we may negate an integer constant T without causing
372 overflow. */
374 bool
376 {
377 tree type;
386 }
388 /* Determine whether an expression T can be cheaply negated using
389 the function negate_expr without introducing undefined overflow. */
391 static bool
393 {
394 tree type;
403 {
408 /* Check that -CST will not overflow type. */
421 /* We want to canonicalize to positive real constants. Pretend
422 that only negative ones can be easily negated. */
430 {
441 }
454 /* -(A + B) -> (-B) - A. */
459 /* -(A + B) -> (-A) - B. */
463 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
473 /* Fall through. */
484 /* In general we can't negate A / B, because if A is INT_MIN and
485 B is 1, we may turn this into INT_MIN / -1 which is undefined
486 and actually traps on some architectures. But if overflow is
487 undefined, we can negate, because - (INT_MIN / 1) is an
488 overflow. */
490 {
493 /* If overflow is undefined then we have to be careful because
494 we ask whether it's ok to associate the negate with the
495 division which is not ok for example for
496 -((a - b) / c) where (-(a - b)) / c may invoke undefined
497 overflow because of negating INT_MIN. So do not use
498 negate_expr_p here but open-code the two important cases. */
503 }
509 /* Negate -((double)float) as (double)(-float). */
511 {
515 }
519 /* Negate -f(x) as f(-x). */
525 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
527 {
531 }
536 }
538 }
540 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
541 simplification is possible.
542 If negate_expr_p would return true for T, NULL_TREE will never be
543 returned. */
545 static tree
547 {
549 tree tem;
552 {
553 /* Convert - (~A) to A + 1. */
579 {
584 }
588 {
593 {
597 }
600 }
623 {
624 /* -(A + B) -> (-B) - A. */
628 {
632 }
634 /* -(A + B) -> (-A) - B. */
636 {
640 }
641 }
645 /* - (A - B) -> B - A */
657 /* Fall through. */
661 {
670 }
676 /* In general we can't negate A / B, because if A is INT_MIN and
677 B is 1, we may turn this into INT_MIN / -1 which is undefined
678 and actually traps on some architectures. But if overflow is
679 undefined, we can negate, because - (INT_MIN / 1) is an
680 overflow. */
682 {
687 {
694 }
695 /* If overflow is undefined then we have to be careful because
696 we ask whether it's ok to associate the negate with the
697 division which is not ok for example for
698 -((a - b) / c) where (-(a - b)) / c may invoke undefined
699 overflow because of negating INT_MIN. So do not use
700 negate_expr_p here but open-code the two important cases. */
709 }
713 /* Convert -((double)float) into (double)(-float). */
715 {
719 }
723 /* Negate -f(x) as f(-x). */
726 {
732 }
736 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
738 {
741 {
748 }
749 }
754 }
757 }
759 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
760 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
761 return NULL_TREE. */
763 static tree
765 {
767 location_t loc;
780 }
781 \f
782 /* Split a tree IN into a constant, literal and variable parts that could be
783 combined with CODE to make IN. "constant" means an expression with
784 TREE_CONSTANT but that isn't an actual constant. CODE must be a
785 commutative arithmetic operation. Store the constant part into *CONP,
786 the literal in *LITP and return the variable part. If a part isn't
787 present, set it to null. If the tree does not decompose in this way,
788 return the entire tree as the variable part and the other parts as null.
790 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
791 case, we negate an operand that was subtracted. Except if it is a
792 literal for which we use *MINUS_LITP instead.
794 If NEGATE_P is true, we are negating all of IN, again except a literal
795 for which we use *MINUS_LITP instead.
797 If IN is itself a literal or constant, return it as appropriate.
799 Note that we do not guarantee that any of the three values will be the
800 same type as IN, but they will have the same signedness and mode. */
802 static tree
805 {
812 /* Strip any conversions that don't change the machine mode or signedness. */
821 /* We can associate addition and subtraction together (even
822 though the C standard doesn't say so) for integers because
823 the value is not affected. For reals, the value might be
824 affected, so we can't. */
827 {
833 /* First see if either of the operands is a literal, then a constant. */
846 /* If we haven't dealt with either operand, this is not a case we can
847 decompose. Otherwise, VAR is either of the ones remaining, if any. */
852 else
855 /* Now do any needed negations. */
862 }
865 {
866 /* -X - 1 is folded to ~X, undo that here. */
869 }
872 else
876 {
883 }
886 }
888 /* Re-associate trees split by the above function. T1 and T2 are
889 either expressions to associate or null. Return the new
890 expression, if any. LOC is the location of the new expression. If
891 we build an operation, do it in TYPE and with CODE. */
893 static tree
895 {
901 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
902 try to fold this since we will have infinite recursion. But do
903 deal with any NEGATE_EXPRs. */
906 {
908 {
921 }
923 {
926 }
930 }
934 }
935 \f
936 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
937 for use in int_const_binop, size_binop and size_diffop. */
939 static bool
941 {
948 {
957 }
962 }
965 /* Combine two integer constants ARG1 and ARG2 under operation CODE
966 to produce a new constant. Return NULL_TREE if we don't know how
967 to evaluate CODE at compile-time. */
969 static tree
972 {
973 wide_int res;
974 tree t;
983 {
999 {
1003 else
1005 }
1008 /* It's unclear from the C standard whether shifts can overflow.
1009 The following code ignores overflow; perhaps a C standard
1010 interpretation ruling is needed. */
1012 else
1019 {
1023 else
1025 }
1029 else
1108 }
1116 }
1118 tree
1120 {
1122 }
1124 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1125 constant. We assume ARG1 and ARG2 have the same data type, or at least
1126 are the same kind of constant and the same machine mode. Return zero if
1127 combining the constants is not allowed in the current operating mode. */
1129 static tree
1131 {
1132 /* Sanity check for the recursive cases. */
1140 {
1146 }
1149 {
1150 machine_mode mode;
1151 REAL_VALUE_TYPE d1;
1152 REAL_VALUE_TYPE d2;
1153 REAL_VALUE_TYPE value;
1154 REAL_VALUE_TYPE result;
1158 /* The following codes are handled by real_arithmetic. */
1160 {
1171 }
1179 /* Don't perform operation if we honor signaling NaNs and
1180 either operand is a NaN. */
1185 /* Don't perform operation if it would raise a division
1186 by zero exception. */
1192 /* If either operand is a NaN, just return it. Otherwise, set up
1193 for floating-point trap; we return an overflow. */
1202 /* Don't constant fold this floating point operation if
1203 the result has overflowed and flag_trapping_math. */
1211 /* Don't constant fold this floating point operation if the
1212 result may dependent upon the run-time rounding mode and
1213 flag_rounding_math is set, or if GCC's software emulation
1214 is unable to accurately represent the result. */
1224 }
1227 {
1228 FIXED_VALUE_TYPE f1;
1229 FIXED_VALUE_TYPE f2;
1230 FIXED_VALUE_TYPE result;
1235 /* The following codes are handled by fixed_arithmetic. */
1237 {
1249 {
1256 }
1261 }
1268 /* Propagate overflow flags. */
1272 }
1275 {
1284 {
1295 mpc_mul);
1309 mpc_div);
1310 /* Fallthru ... */
1316 {
1317 /* Keep this algorithm in sync with
1318 tree-complex.c:expand_complex_div_straight().
1320 Expand complex division to scalars, straightforward algorithm.
1321 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1322 t = br*br + bi*bi
1323 */
1324 tree magsquared
1328 tree t1
1332 tree t2
1339 }
1340 else
1341 {
1342 /* Keep this algorithm in sync with
1343 tree-complex.c:expand_complex_div_wide().
1345 Expand complex division to scalars, modified algorithm to minimize
1346 overflow with wide input ranges. */
1352 {
1353 /* In the TRUE branch, we compute
1354 ratio = br/bi;
1355 div = (br * ratio) + bi;
1356 tr = (ar * ratio) + ai;
1357 ti = (ai * ratio) - ar;
1358 tr = tr / div;
1359 ti = ti / div; */
1370 }
1371 else
1372 {
1373 /* In the FALSE branch, we compute
1374 ratio = d/c;
1375 divisor = (d * ratio) + c;
1376 tr = (b * ratio) + a;
1377 ti = b - (a * ratio);
1378 tr = tr / div;
1379 ti = ti / div; */
1391 }
1392 }
1397 }
1401 }
1405 {
1411 {
1417 /* It is possible that const_binop cannot handle the given
1418 code and return NULL_TREE */
1421 }
1424 }
1426 /* Shifts allow a scalar offset for a vector. */
1429 {
1435 {
1440 /* It is possible that const_binop cannot handle the given
1441 code and return NULL_TREE. */
1444 }
1447 }
1449 }
1451 /* Overload that adds a TYPE parameter to be able to dispatch
1452 to fold_relational_const. */
1454 tree
1456 {
1460 /* ??? Until we make the const_binop worker take the type of the
1461 result as argument put those cases that need it here. */
1463 {
1474 {
1490 {
1496 }
1499 }
1505 {
1530 {
1543 }
1546 }
1549 }
1554 /* Make sure type and arg0 have the same saturating flag. */
1559 }
1561 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1562 Return zero if computing the constants is not possible. */
1564 tree
1566 {
1568 {
1569 CASE_CONVERT:
1584 {
1585 /* Can't call fold_negate_const directly here as that doesn't
1586 handle all cases and we might not be able to negate some
1587 constants. */
1592 }
1601 {
1605 }
1611 /* Perform BIT_NOT_EXPR on each element individually. */
1613 {
1615 tree elem;
1620 {
1626 }
1629 }
1651 {
1670 else
1674 {
1678 }
1681 }
1686 {
1700 {
1705 }
1708 {
1712 }
1715 }
1719 }
1722 }
1724 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1725 indicates which particular sizetype to create. */
1727 tree
1729 {
1731 }
1732 \f
1733 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1734 is a tree code. The type of the result is taken from the operands.
1735 Both must be equivalent integer types, ala int_binop_types_match_p.
1736 If the operands are constant, so is the result. */
1738 tree
1740 {
1749 /* Handle the special case of two integer constants faster. */
1751 {
1752 /* And some specific cases even faster than that. */
1754 {
1759 }
1761 {
1764 }
1766 {
1769 }
1771 /* Handle general case of two integer constants. For sizetype
1772 constant calculations we always want to know about overflow,
1773 even in the unsigned case. */
1775 }
1778 }
1780 /* Given two values, either both of sizetype or both of bitsizetype,
1781 compute the difference between the two values. Return the value
1782 in signed type corresponding to the type of the operands. */
1784 tree
1786 {
1788 tree ctype;
1793 /* If the type is already signed, just do the simple thing. */
1801 else
1804 /* If either operand is not a constant, do the conversions to the signed
1805 type and subtract. The hardware will do the right thing with any
1806 overflow in the subtraction. */
1812 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1813 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1814 overflow) and negate (which can't either). Special-case a result
1815 of zero while we're here. */
1821 else
1825 MINUS_EXPR,
1827 }
1828 \f
1829 /* A subroutine of fold_convert_const handling conversions of an
1830 INTEGER_CST to another integer type. */
1832 static tree
1834 {
1835 /* Given an integer constant, make new constant with new type,
1836 appropriately sign-extended or truncated. Use widest_int
1837 so that any extension is done according ARG1's type. */
1841 }
1843 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1844 to an integer type. */
1846 static tree
1848 {
1850 tree t;
1852 /* The following code implements the floating point to integer
1853 conversion rules required by the Java Language Specification,
1854 that IEEE NaNs are mapped to zero and values that overflow
1855 the target precision saturate, i.e. values greater than
1856 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1857 are mapped to INT_MIN. These semantics are allowed by the
1858 C and C++ standards that simply state that the behavior of
1859 FP-to-integer conversion is unspecified upon overflow. */
1861 wide_int val;
1862 REAL_VALUE_TYPE r;
1866 {
1873 }
1875 /* If R is NaN, return zero and show we have an overflow. */
1877 {
1880 }
1882 /* See if R is less than the lower bound or greater than the
1883 upper bound. */
1886 {
1890 {
1893 }
1894 }
1897 {
1900 {
1903 {
1906 }
1907 }
1908 }
1915 }
1917 /* A subroutine of fold_convert_const handling conversions of a
1918 FIXED_CST to an integer type. */
1920 static tree
1922 {
1923 tree t;
1927 /* Right shift FIXED_CST to temp by fbit. */
1931 {
1933 HOST_BITS_PER_DOUBLE_INT,
1936 /* Left shift temp to temp_trunc by fbit. */
1938 HOST_BITS_PER_DOUBLE_INT,
1940 }
1941 else
1942 {
1945 }
1947 /* If FIXED_CST is negative, we need to round the value toward 0.
1948 By checking if the fractional bits are not zero to add 1 to temp. */
1954 /* Given a fixed-point constant, make new constant with new type,
1955 appropriately sign-extended or truncated. */
1963 }
1965 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1966 to another floating point type. */
1968 static tree
1970 {
1971 REAL_VALUE_TYPE value;
1972 tree t;
1977 /* If converting an infinity or NAN to a representation that doesn't
1978 have one, set the overflow bit so that we can produce some kind of
1979 error message at the appropriate point if necessary. It's not the
1980 most user-friendly message, but it's better than nothing. */
1987 /* Regular overflow, conversion produced an infinity in a mode that
1988 can't represent them. */
1993 else
1996 }
1998 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1999 to a floating point type. */
2001 static tree
2003 {
2004 REAL_VALUE_TYPE value;
2005 tree t;
2012 }
2014 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2015 to another fixed-point type. */
2017 static tree
2019 {
2020 FIXED_VALUE_TYPE value;
2021 tree t;
2028 /* Propagate overflow flags. */
2032 }
2034 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2035 to a fixed-point type. */
2037 static tree
2039 {
2040 FIXED_VALUE_TYPE value;
2041 tree t;
2043 double_int di;
2050 else
2058 /* Propagate overflow flags. */
2062 }
2064 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2065 to a fixed-point type. */
2067 static tree
2069 {
2070 FIXED_VALUE_TYPE value;
2071 tree t;
2079 /* Propagate overflow flags. */
2083 }
2085 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2086 type TYPE. If no simplification can be done return NULL_TREE. */
2088 static tree
2090 {
2096 {
2103 }
2105 {
2112 }
2114 {
2121 }
2123 }
2125 /* Construct a vector of zero elements of vector type TYPE. */
2127 static tree
2129 {
2130 tree t;
2134 }
2136 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2138 bool
2140 {
2155 {
2174 }
2175 }
2177 /* Convert expression ARG to type TYPE. Used by the middle-end for
2178 simple conversions in preference to calling the front-end's convert. */
2180 tree
2182 {
2184 tree tem;
2195 {
2198 /* Handle conversions between pointers to different address spaces. */
2203 /* fall through */
2208 {
2212 }
2226 {
2230 }
2232 {
2236 }
2238 {
2242 }
2245 {
2263 }
2268 {
2272 }
2275 {
2289 }
2293 {
2302 integer_zero_node));
2304 {
2308 {
2314 }
2322 }
2326 }
2344 }
2345 fold_convert_exit:
2348 }
2349 \f
2350 /* Return false if expr can be assumed not to be an lvalue, true
2351 otherwise. */
2353 static bool
2355 {
2356 /* We only need to wrap lvalue tree codes. */
2358 {
2389 /* Assume the worst for front-end tree codes. */
2393 }
2396 }
2398 /* Return an expr equal to X but certainly not valid as an lvalue. */
2400 tree
2402 {
2403 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2404 us. */
2411 }
2413 /* When pedantic, return an expr equal to X but certainly not valid as a
2414 pedantic lvalue. Otherwise, return X. */
2416 static tree
2418 {
2420 }
2421 \f
2422 /* Given a tree comparison code, return the code that is the logical inverse.
2423 It is generally not safe to do this for floating-point comparisons, except
2424 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2425 ERROR_MARK in this case. */
2427 enum tree_code
2429 {
2435 {
2466 }
2467 }
2469 /* Similar, but return the comparison that results if the operands are
2470 swapped. This is safe for floating-point. */
2472 enum tree_code
2474 {
2476 {
2502 }
2503 }
2506 /* Convert a comparison tree code from an enum tree_code representation
2507 into a compcode bit-based encoding. This function is the inverse of
2508 compcode_to_comparison. */
2510 static enum comparison_code
2512 {
2514 {
2545 }
2546 }
2548 /* Convert a compcode bit-based encoding of a comparison operator back
2549 to GCC's enum tree_code representation. This function is the
2550 inverse of comparison_to_compcode. */
2552 static enum tree_code
2554 {
2556 {
2587 }
2588 }
2590 /* Return a tree for the comparison which is the combination of
2591 doing the AND or OR (depending on CODE) of the two operations LCODE
2592 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2593 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2594 if this makes the transformation invalid. */
2596 tree
2601 {
2608 {
2619 }
2622 {
2623 /* Eliminate unordered comparisons, as well as LTGT and ORD
2624 which are not used unless the mode has NaNs. */
2630 }
2632 {
2633 /* Check that the original operation and the optimized ones will trap
2634 under the same condition. */
2645 /* In a short-circuited boolean expression the LHS might be
2646 such that the RHS, if evaluated, will never trap. For
2647 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2648 if neither x nor y is NaN. (This is a mixed blessing: for
2649 example, the expression above will never trap, hence
2650 optimizing it to x < y would be invalid). */
2655 /* If the comparison was short-circuited, and only the RHS
2656 trapped, we may now generate a spurious trap. */
2661 /* If we changed the conditions that cause a trap, we lose. */
2664 }
2670 else
2671 {
2676 }
2677 }
2678 \f
2679 /* Return nonzero if two operands (typically of the same tree node)
2680 are necessarily equal. If either argument has side-effects this
2681 function returns zero. FLAGS modifies behavior as follows:
2683 If OEP_ONLY_CONST is set, only return nonzero for constants.
2684 This function tests whether the operands are indistinguishable;
2685 it does not test whether they are equal using C's == operation.
2686 The distinction is important for IEEE floating point, because
2687 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2688 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2690 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2691 even though it may hold multiple values during a function.
2692 This is because a GCC tree node guarantees that nothing else is
2693 executed between the evaluation of its "operands" (which may often
2694 be evaluated in arbitrary order). Hence if the operands themselves
2695 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2696 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2697 unset means assuming isochronic (or instantaneous) tree equivalence.
2698 Unless comparing arbitrary expression trees, such as from different
2699 statements, this flag can usually be left unset.
2701 If OEP_PURE_SAME is set, then pure functions with identical arguments
2702 are considered the same. It is used when the caller has other ways
2703 to ensure that global memory is unchanged in between. */
2705 int
2707 {
2708 /* If either is ERROR_MARK, they aren't equal. */
2714 /* Similar, if either does not have a type (like a released SSA name),
2715 they aren't equal. */
2719 /* Check equality of integer constants before bailing out due to
2720 precision differences. */
2724 /* If both types don't have the same signedness, then we can't consider
2725 them equal. We must check this before the STRIP_NOPS calls
2726 because they may change the signedness of the arguments. As pointers
2727 strictly don't have a signedness, require either two pointers or
2728 two non-pointers as well. */
2733 /* We cannot consider pointers to different address space equal. */
2739 /* If both types don't have the same precision, then it is not safe
2740 to strip NOPs. */
2748 /* In case both args are comparisons but with different comparison
2749 code, try to swap the comparison operands of one arg to produce
2750 a match and compare that variant. */
2754 {
2762 }
2765 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2769 /* This is needed for conversions and for COMPONENT_REF.
2770 Might as well play it safe and always test this. */
2776 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2777 We don't care about side effects in that case because the SAVE_EXPR
2778 takes care of that for us. In all other cases, two expressions are
2779 equal if they have no side effects. If we have two identical
2780 expressions with side effects that should be treated the same due
2781 to the only side effects being identical SAVE_EXPR's, that will
2782 be detected in the recursive calls below.
2783 If we are taking an invariant address of two identical objects
2784 they are necessarily equal as well. */
2791 /* Next handle constant cases, those for which we can return 1 even
2792 if ONLY_CONST is set. */
2795 {
2810 {
2811 /* If we do not distinguish between signed and unsigned zero,
2812 consider them equal. */
2815 }
2819 {
2826 {
2830 }
2832 }
2836 flags)
2838 flags));
2852 }
2857 /* Define macros to test an operand from arg0 and arg1 for equality and a
2858 variant that allows null and views null as being different from any
2859 non-null value. In the latter case, if either is null, the both
2860 must be; otherwise, do the normal comparison. */
2861 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2862 TREE_OPERAND (arg1, N), flags)
2864 #define OP_SAME_WITH_NULL(N) \
2865 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2866 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2869 {
2871 /* Two conversions are equal only if signedness and modes match. */
2873 {
2874 CASE_CONVERT:
2882 }
2892 /* For commutative ops, allow the other order. */
2900 /* If either of the pointer (or reference) expressions we are
2901 dereferencing contain a side effect, these cannot be equal,
2902 but their addresses can be. */
2909 {
2924 /* Require equal access sizes, and similar pointer types.
2925 We can have incomplete types for array references of
2926 variable-sized arrays from the Fortran frontend
2927 though. Also verify the types are compatible. */
2935 || (alias_ptr_types_compatible_p
2947 /* TARGET_MEM_REF require equal extra operands. */
2955 /* Operands 2 and 3 may be null.
2956 Compare the array index by value if it is constant first as we
2957 may have different types but same value here. */
2968 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2969 may be NULL when we're called to compare MEM_EXPRs. */
2984 }
2988 {
3006 /* The multiplcation operands are commutative. */
3007 /* FALLTHRU */
3015 /* Otherwise take into account this is a commutative operation. */
3028 }
3032 {
3036 /* If not both CALL_EXPRs are either internal or normal function
3037 functions, then they are not equal. */
3040 {
3041 /* If the CALL_EXPRs call different internal functions, then they
3042 are not equal. */
3045 }
3046 else
3047 {
3048 /* If the CALL_EXPRs call different functions, then they are not
3049 equal. */
3051 flags))
3053 }
3055 {
3059 else
3063 }
3065 /* Now see if all the arguments are the same. */
3066 {
3077 /* If we get here and both argument lists are exhausted
3078 then the CALL_EXPRs are equal. */
3080 }
3083 }
3086 /* Consider __builtin_sqrt equal to sqrt. */
3094 }
3096 #undef OP_SAME
3097 #undef OP_SAME_WITH_NULL
3098 }
3099 \f
3100 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3101 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3103 When in doubt, return 0. */
3105 static int
3107 {
3119 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3120 and see if the inner values are the same. This removes any
3121 signedness comparison, which doesn't matter here. */
3128 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3129 actual comparison operand, ARG0.
3131 First throw away any conversions to wider types
3132 already present in the operands. */
3141 {
3144 /* Make sure shorter operand is extended the right way
3145 to match the longer operand. */
3151 }
3154 }
3155 \f
3156 /* See if ARG is an expression that is either a comparison or is performing
3157 arithmetic on comparisons. The comparisons must only be comparing
3158 two different values, which will be stored in *CVAL1 and *CVAL2; if
3159 they are nonzero it means that some operands have already been found.
3160 No variables may be used anywhere else in the expression except in the
3161 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3162 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3164 If this is true, return 1. Otherwise, return zero. */
3166 static int
3168 {
3172 /* We can handle some of the tcc_expression cases here. */
3182 {
3183 /* If we've already found a CVAL1 or CVAL2, this expression is
3184 two complex to handle. */
3190 }
3193 {
3216 /* First see if we can handle the first operand, then the second. For
3217 the second operand, we know *CVAL1 can't be zero. It must be that
3218 one side of the comparison is each of the values; test for the
3219 case where this isn't true by failing if the two operands
3220 are the same. */
3229 ;
3233 ;
3234 else
3238 ;
3242 ;
3243 else
3250 }
3251 }
3252 \f
3253 /* ARG is a tree that is known to contain just arithmetic operations and
3254 comparisons. Evaluate the operations in the tree substituting NEW0 for
3255 any occurrence of OLD0 as an operand of a comparison and likewise for
3256 NEW1 and OLD1. */
3258 static tree
3261 {
3266 /* We can handle some of the tcc_expression cases here. */
3274 {
3289 {
3308 }
3309 /* Fall through - ??? */
3312 {
3316 /* We need to check both for exact equality and tree equality. The
3317 former will be true if the operand has a side-effect. In that
3318 case, we know the operand occurred exactly once. */
3331 }
3335 }
3336 }
3337 \f
3338 /* Return a tree for the case when the result of an expression is RESULT
3339 converted to TYPE and OMITTED was previously an operand of the expression
3340 but is now not needed (e.g., we folded OMITTED * 0).
3342 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3343 the conversion of RESULT to TYPE. */
3345 tree
3347 {
3350 /* If the resulting operand is an empty statement, just return the omitted
3351 statement casted to void. */
3361 }
3363 /* Return a tree for the case when the result of an expression is RESULT
3364 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3365 of the expression but are now not needed.
3367 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3368 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3369 evaluated before OMITTED2. Otherwise, if neither has side effects,
3370 just do the conversion of RESULT to TYPE. */
3372 tree
3375 {
3384 }
3386 \f
3387 /* Return a simplified tree node for the truth-negation of ARG. This
3388 never alters ARG itself. We assume that ARG is an operation that
3389 returns a truth value (0 or 1).
3391 FIXME: one would think we would fold the result, but it causes
3392 problems with the dominator optimizer. */
3394 static tree
3396 {
3401 /* If this is a comparison, we can simply invert it, except for
3402 floating-point non-equality comparisons, in which case we just
3403 enclose a TRUTH_NOT_EXPR around what we have. */
3406 {
3409 && flag_trapping_math
3420 }
3423 {
3442 /* Here we can invert either operand. We invert the first operand
3443 unless the second operand is a TRUTH_NOT_EXPR in which case our
3444 result is the XOR of the first operand with the inside of the
3445 negation of the second operand. */
3450 else
3473 {
3480 /* A COND_EXPR may have a throw as one operand, which
3481 then has void type. Just leave void operands
3482 as they are. */
3488 }
3500 CASE_CONVERT:
3504 /* ... fall through ... */
3526 }
3527 }
3529 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3530 assume that ARG is an operation that returns a truth value (0 or 1
3531 for scalars, 0 or -1 for vectors). Return the folded expression if
3532 folding is successful. Otherwise, return NULL_TREE. */
3534 static tree
3536 {
3539 ? BIT_NOT_EXPR
3542 }
3544 /* Return a simplified tree node for the truth-negation of ARG. This
3545 never alters ARG itself. We assume that ARG is an operation that
3546 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3548 tree
3550 {
3556 ? BIT_NOT_EXPR
3559 }
3561 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3562 operands are another bit-wise operation with a common input. If so,
3563 distribute the bit operations to save an operation and possibly two if
3564 constants are involved. For example, convert
3565 (A | B) & (A | C) into A | (B & C)
3566 Further simplification will occur if B and C are constants.
3568 If this optimization cannot be done, 0 will be returned. */
3570 static tree
3573 {
3574 tree common;
3584 {
3588 }
3590 {
3594 }
3596 {
3600 }
3602 {
3606 }
3607 else
3615 }
3617 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3618 with code CODE. This optimization is unsafe. */
3619 static tree
3622 {
3626 /* (A / C) +- (B / C) -> (A +- B) / C. */
3636 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3641 {
3653 }
3656 }
3657 \f
3658 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3659 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3661 static tree
3664 {
3668 {
3675 }
3689 }
3691 /* Optimize a bit-field compare.
3693 There are two cases: First is a compare against a constant and the
3694 second is a comparison of two items where the fields are at the same
3695 bit position relative to the start of a chunk (byte, halfword, word)
3696 large enough to contain it. In these cases we can avoid the shift
3697 implicit in bitfield extractions.
3699 For constants, we emit a compare of the shifted constant with the
3700 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3701 compared. For two fields at the same position, we do the ANDs with the
3702 similar mask and compare the result of the ANDs.
3704 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3705 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3706 are the left and right operands of the comparison, respectively.
3708 If the optimization described above can be done, we return the resulting
3709 tree. Otherwise we return zero. */
3711 static tree
3714 {
3717 tree unsigned_type;
3723 tree mask;
3724 tree offset;
3726 /* Get all the information about the extractions being done. If the bit size
3727 if the same as the size of the underlying object, we aren't doing an
3728 extraction at all and so can do nothing. We also don't want to
3729 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3730 then will no longer be able to replace it. */
3738 {
3739 /* If this is not a constant, we can only do something if bit positions,
3740 sizes, and signedness are the same. */
3748 }
3750 /* See if we can find a mode to refer to this field. We should be able to,
3751 but fail if we can't. */
3760 /* Set signed and unsigned types of the precision of this mode for the
3761 shifts below. */
3764 /* Compute the bit position and size for the new reference and our offset
3765 within it. If the new reference is the same size as the original, we
3766 won't optimize anything, so return zero. */
3776 /* Make the mask to be used against the extracted field. */
3783 /* If not comparing with constant, just rework the comparison
3784 and return. */
3788 unsigned_type,
3791 mask),
3794 unsigned_type,
3797 mask));
3799 /* Otherwise, we are handling the constant case. See if the constant is too
3800 big for the field. Warn and return a tree of for 0 (false) if so. We do
3801 this not only for its own sake, but to avoid having to test for this
3802 error case below. If we didn't, we might generate wrong code.
3804 For unsigned fields, the constant shifted right by the field length should
3805 be all zero. For signed fields, the high-order bits should agree with
3806 the sign bit. */
3809 {
3811 {
3815 }
3816 }
3817 else
3818 {
3821 {
3825 }
3826 }
3828 /* Single-bit compares should always be against zero. */
3830 {
3833 }
3835 /* Make a new bitfield reference, shift the constant over the
3836 appropriate number of bits and mask it with the computed mask
3837 (in case this was a signed field). If we changed it, make a new one. */
3844 mask);
3849 }
3850 \f
3851 /* Subroutine for fold_truth_andor_1: decode a field reference.
3853 If EXP is a comparison reference, we return the innermost reference.
3855 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3856 set to the starting bit number.
3858 If the innermost field can be completely contained in a mode-sized
3859 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3861 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3862 otherwise it is not changed.
3864 *PUNSIGNEDP is set to the signedness of the field.
3866 *PMASK is set to the mask used. This is either contained in a
3867 BIT_AND_EXPR or derived from the width of the field.
3869 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3871 Return 0 if this is not a component reference or is one that we can't
3872 do anything with. */
3874 static tree
3879 {
3883 tree unsigned_type;
3886 /* All the optimizations using this function assume integer fields.
3887 There are problems with FP fields since the type_for_size call
3888 below can fail for, e.g., XFmode. */
3892 /* We are interested in the bare arrangement of bits, so strip everything
3893 that doesn't affect the machine mode. However, record the type of the
3894 outermost expression if it may matter below. */
3901 {
3907 }
3916 /* If the number of bits in the reference is the same as the bitsize of
3917 the outer type, then the outer type gives the signedness. Otherwise
3918 (in case of a small bitfield) the signedness is unchanged. */
3922 /* Compute the mask to access the bitfield. */
3931 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3939 }
3941 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3942 bit positions and MASK is SIGNED. */
3944 static int
3946 {
3950 /* If this function returns true when the type of the mask is
3951 UNSIGNED, then there will be errors. In particular see
3952 gcc.c-torture/execute/990326-1.c. There does not appear to be
3953 any documentation paper trail as to why this is so. But the pre
3954 wide-int worked with that restriction and it has been preserved
3955 here. */
3960 }
3962 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3963 represents the sign bit of EXP's type. If EXP represents a sign
3964 or zero extension, also test VAL against the unextended type.
3965 The return value is the (sub)expression whose sign bit is VAL,
3966 or NULL_TREE otherwise. */
3968 tree
3970 {
3972 tree t;
3974 /* Tree EXP must have an integral type. */
3979 /* Tree VAL must be an integer constant. */
3988 /* Handle extension from a narrower type. */
3994 }
3996 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3997 to be evaluated unconditionally. */
3999 static int
4001 {
4002 /* Strip any conversions that don't change the machine mode. */
4011 /* Don't regard global variables as simple. They may be
4012 allocated in ways unknown to the compiler (shared memory,
4013 #pragma weak, etc). */
4016 /* Weakrefs are not safe to be read, since they can be NULL.
4017 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4018 have DECL_WEAK flag set. */
4020 /* Loading a static variable is unduly expensive, but global
4021 registers aren't expensive. */
4023 }
4025 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4026 to be evaluated unconditionally.
4027 I addition to simple_operand_p, we assume that comparisons, conversions,
4028 and logic-not operations are simple, if their operands are simple, too. */
4030 static bool
4032 {
4052 }
4054 \f
4055 /* The following functions are subroutines to fold_range_test and allow it to
4056 try to change a logical combination of comparisons into a range test.
4058 For example, both
4059 X == 2 || X == 3 || X == 4 || X == 5
4060 and
4061 X >= 2 && X <= 5
4062 are converted to
4063 (unsigned) (X - 2) <= 3
4065 We describe each set of comparisons as being either inside or outside
4066 a range, using a variable named like IN_P, and then describe the
4067 range with a lower and upper bound. If one of the bounds is omitted,
4068 it represents either the highest or lowest value of the type.
4070 In the comments below, we represent a range by two numbers in brackets
4071 preceded by a "+" to designate being inside that range, or a "-" to
4072 designate being outside that range, so the condition can be inverted by
4073 flipping the prefix. An omitted bound is represented by a "-". For
4074 example, "- [-, 10]" means being outside the range starting at the lowest
4075 possible value and ending at 10, in other words, being greater than 10.
4076 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4077 always false.
4079 We set up things so that the missing bounds are handled in a consistent
4080 manner so neither a missing bound nor "true" and "false" need to be
4081 handled using a special case. */
4083 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4084 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4085 and UPPER1_P are nonzero if the respective argument is an upper bound
4086 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4087 must be specified for a comparison. ARG1 will be converted to ARG0's
4088 type if both are specified. */
4090 static tree
4093 {
4094 tree tem;
4098 /* If neither arg represents infinity, do the normal operation.
4099 Else, if not a comparison, return infinity. Else handle the special
4100 comparison rules. Note that most of the cases below won't occur, but
4101 are handled for consistency. */
4104 {
4109 }
4114 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4115 for neither. In real maths, we cannot assume open ended ranges are
4116 the same. But, this is computer arithmetic, where numbers are finite.
4117 We can therefore make the transformation of any unbounded range with
4118 the value Z, Z being greater than any representable number. This permits
4119 us to treat unbounded ranges as equal. */
4123 {
4144 }
4147 }
4148 \f
4149 /* Helper routine for make_range. Perform one step for it, return
4150 new expression if the loop should continue or NULL_TREE if it should
4151 stop. */
4153 tree
4157 {
4163 {
4165 /* We can only do something if the range is testing for zero. */
4174 /* We can only do something if the range is testing for zero
4175 and if the second operand is an integer constant. Note that
4176 saying something is "in" the range we make is done by
4177 complementing IN_P since it will set in the initial case of
4178 being not equal to zero; "out" is leaving it alone. */
4185 {
4206 }
4208 /* If this is an unsigned comparison, we also know that EXP is
4209 greater than or equal to zero. We base the range tests we make
4210 on that fact, so we record it here so we can parse existing
4211 range tests. We test arg0_type since often the return type
4212 of, e.g. EQ_EXPR, is boolean. */
4214 {
4218 NULL_TREE))
4223 /* If the high bound is missing, but we have a nonzero low
4224 bound, reverse the range so it goes from zero to the low bound
4225 minus 1. */
4227 {
4232 }
4233 }
4241 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4242 low and high are non-NULL, then normalize will DTRT. */
4245 {
4250 }
4252 /* (-x) IN [a,b] -> x in [-b, -a] */
4264 /* ~ X -> -X - 1 */
4273 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4274 move a constant to the other side. */
4279 /* If EXP is signed, any overflow in the computation is undefined,
4280 so we don't worry about it so long as our computations on
4281 the bounds don't overflow. For unsigned, overflow is defined
4282 and this is exactly the right thing. */
4294 normalize:
4295 /* Check for an unsigned range which has wrapped around the maximum
4296 value thus making n_high < n_low, and normalize it. */
4298 {
4304 /* If the range is of the form +/- [ x+1, x ], we won't
4305 be able to normalize it. But then, it represents the
4306 whole range or the empty set, so make it
4307 +/- [ -, - ]. */
4311 else
4313 }
4314 else
4322 CASE_CONVERT:
4340 /* If we're converting arg0 from an unsigned type, to exp,
4341 a signed type, we will be doing the comparison as unsigned.
4342 The tests above have already verified that LOW and HIGH
4343 are both positive.
4345 So we have to ensure that we will handle large unsigned
4346 values the same way that the current signed bounds treat
4347 negative values. */
4350 {
4351 tree high_positive;
4352 tree equiv_type;
4353 /* For fixed-point modes, we need to pass the saturating flag
4354 as the 2nd parameter. */
4356 equiv_type
4359 else
4360 equiv_type
4363 /* A range without an upper bound is, naturally, unbounded.
4364 Since convert would have cropped a very large value, use
4365 the max value for the destination type. */
4366 high_positive
4373 high_positive),
4376 /* If the low bound is specified, "and" the range with the
4377 range for which the original unsigned value will be
4378 positive. */
4380 {
4383 integer_zero_node),
4384 high_positive))
4388 }
4389 else
4390 {
4391 /* Otherwise, "or" the range with the range of the input
4392 that will be interpreted as negative. */
4395 integer_zero_node),
4396 high_positive))
4400 }
4401 }
4410 }
4411 }
4413 /* Given EXP, a logical expression, set the range it is testing into
4414 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4415 actually being tested. *PLOW and *PHIGH will be made of the same
4416 type as the returned expression. If EXP is not a comparison, we
4417 will most likely not be returning a useful value and range. Set
4418 *STRICT_OVERFLOW_P to true if the return value is only valid
4419 because signed overflow is undefined; otherwise, do not change
4420 *STRICT_OVERFLOW_P. */
4422 tree
4425 {
4433 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4434 and see if we can refine the range. Some of the cases below may not
4435 happen, but it doesn't seem worth worrying about this. We "continue"
4436 the outer loop when we've changed something; otherwise we "break"
4437 the switch, which will "break" the while. */
4443 {
4449 {
4457 }
4466 }
4468 /* If EXP is a constant, we can evaluate whether this is true or false. */
4470 {
4477 }
4481 }
4482 \f
4483 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4484 type, TYPE, return an expression to test if EXP is in (or out of, depending
4485 on IN_P) the range. Return 0 if the test couldn't be created. */
4487 tree
4490 {
4493 #ifdef HAVE_canonicalize_funcptr_for_compare
4494 /* Disable this optimization for function pointer expressions
4495 on targets that require function pointer canonicalization. */
4500 #endif
4503 {
4509 }
4527 {
4529 {
4533 }
4535 }
4537 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4539 {
4543 {
4545 {
4548 etype
4550 else
4553 }
4556 }
4557 }
4559 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4560 This requires wrap-around arithmetics for the type of the expression.
4561 First make sure that arithmetics in this type is valid, then make sure
4562 that it wraps around. */
4568 {
4571 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4572 for the type in question, as we rely on this here. */
4582 else
4584 }
4594 {
4596 {
4601 }
4603 }
4611 }
4612 \f
4613 /* Return the predecessor of VAL in its type, handling the infinite case. */
4615 static tree
4617 {
4623 else
4626 }
4628 /* Return the successor of VAL in its type, handling the infinite case. */
4630 static tree
4632 {
4638 else
4641 }
4643 /* Given two ranges, see if we can merge them into one. Return 1 if we
4644 can, 0 if we can't. Set the output range into the specified parameters. */
4646 bool
4649 {
4653 tree tem;
4663 /* Make range 0 be the range that starts first, or ends last if they
4664 start at the same value. Swap them if it isn't. */
4667 || (lowequal
4670 {
4674 }
4676 /* Now flag two cases, whether the ranges are disjoint or whether the
4677 second range is totally subsumed in the first. Note that the tests
4678 below are simplified by the ones above. */
4684 /* We now have four cases, depending on whether we are including or
4685 excluding the two ranges. */
4687 {
4688 /* If they don't overlap, the result is false. If the second range
4689 is a subset it is the result. Otherwise, the range is from the start
4690 of the second to the end of the first. */
4695 else
4697 }
4700 {
4701 /* If they don't overlap, the result is the first range. If they are
4702 equal, the result is false. If the second range is a subset of the
4703 first, and the ranges begin at the same place, we go from just after
4704 the end of the second range to the end of the first. If the second
4705 range is not a subset of the first, or if it is a subset and both
4706 ranges end at the same place, the range starts at the start of the
4707 first range and ends just before the second range.
4708 Otherwise, we can't describe this as a single range. */
4714 {
4719 {
4720 /* We are in the weird situation where high0 > high1 but
4721 high1 has no successor. Punt. */
4723 }
4724 }
4726 {
4731 {
4732 /* low0 < low1 but low1 has no predecessor. Punt. */
4734 }
4735 }
4736 else
4738 }
4741 {
4742 /* If they don't overlap, the result is the second range. If the second
4743 is a subset of the first, the result is false. Otherwise,
4744 the range starts just after the first range and ends at the
4745 end of the second. */
4750 else
4751 {
4756 {
4757 /* high1 > high0 but high0 has no successor. Punt. */
4759 }
4760 }
4761 }
4763 else
4764 {
4765 /* The case where we are excluding both ranges. Here the complex case
4766 is if they don't overlap. In that case, the only time we have a
4767 range is if they are adjacent. If the second is a subset of the
4768 first, the result is the first. Otherwise, the range to exclude
4769 starts at the beginning of the first range and ends at the end of the
4770 second. */
4772 {
4777 else
4778 {
4779 /* Canonicalize - [min, x] into - [-, x]. */
4782 {
4787 /* FALLTHROUGH */
4800 }
4802 /* Canonicalize - [x, max] into - [x, -]. */
4805 {
4810 /* FALLTHROUGH */
4826 }
4828 /* The ranges might be also adjacent between the maximum and
4829 minimum values of the given type. For
4830 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4831 return + [x + 1, y - 1]. */
4833 {
4840 }
4841 else
4843 }
4844 }
4847 else
4849 }
4853 }
4854 \f
4856 /* Subroutine of fold, looking inside expressions of the form
4857 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4858 of the COND_EXPR. This function is being used also to optimize
4859 A op B ? C : A, by reversing the comparison first.
4861 Return a folded expression whose code is not a COND_EXPR
4862 anymore, or NULL_TREE if no folding opportunity is found. */
4864 static tree
4867 {
4872 tree tem;
4877 /* If we have A op 0 ? A : -A, consider applying the following
4878 transformations:
4880 A == 0? A : -A same as -A
4881 A != 0? A : -A same as A
4882 A >= 0? A : -A same as abs (A)
4883 A > 0? A : -A same as abs (A)
4884 A <= 0? A : -A same as -abs (A)
4885 A < 0? A : -A same as -abs (A)
4887 None of these transformations work for modes with signed
4888 zeros. If A is +/-0, the first two transformations will
4889 change the sign of the result (from +0 to -0, or vice
4890 versa). The last four will fix the sign of the result,
4891 even though the original expressions could be positive or
4892 negative, depending on the sign of A.
4894 Note that all these transformations are correct if A is
4895 NaN, since the two alternatives (A and -A) are also NaNs. */
4902 /* In the case that A is of the form X-Y, '-A' (arg2) may
4903 have already been folded to Y-X, check for that. */
4911 {
4925 /* Fall through. */
4947 }
4949 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4950 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4951 both transformations are correct when A is NaN: A != 0
4952 is then true, and A == 0 is false. */
4956 {
4961 }
4963 /* Try some transformations of A op B ? A : B.
4965 A == B? A : B same as B
4966 A != B? A : B same as A
4967 A >= B? A : B same as max (A, B)
4968 A > B? A : B same as max (B, A)
4969 A <= B? A : B same as min (A, B)
4970 A < B? A : B same as min (B, A)
4972 As above, these transformations don't work in the presence
4973 of signed zeros. For example, if A and B are zeros of
4974 opposite sign, the first two transformations will change
4975 the sign of the result. In the last four, the original
4976 expressions give different results for (A=+0, B=-0) and
4977 (A=-0, B=+0), but the transformed expressions do not.
4979 The first two transformations are correct if either A or B
4980 is a NaN. In the first transformation, the condition will
4981 be false, and B will indeed be chosen. In the case of the
4982 second transformation, the condition A != B will be true,
4983 and A will be chosen.
4985 The conversions to max() and min() are not correct if B is
4986 a number and A is not. The conditions in the original
4987 expressions will be false, so all four give B. The min()
4988 and max() versions would give a NaN instead. */
4991 /* Avoid these transformations if the COND_EXPR may be used
4992 as an lvalue in the C++ front-end. PR c++/19199. */
4993 && (in_gimple_form
4999 {
5004 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5006 {
5010 }
5013 {
5022 /* In C++ a ?: expression can be an lvalue, so put the
5023 operand which will be used if they are equal first
5024 so that we can convert this back to the
5025 corresponding COND_EXPR. */
5027 {
5036 }
5043 {
5052 }
5067 }
5068 }
5070 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5071 we might still be able to simplify this. For example,
5072 if C1 is one less or one more than C2, this might have started
5073 out as a MIN or MAX and been transformed by this function.
5074 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5080 {
5084 /* We can replace A with C1 in this case. */
5089 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5090 MIN_EXPR, to preserve the signedness of the comparison. */
5092 OEP_ONLY_CONST)
5096 OEP_ONLY_CONST))
5097 {
5100 arg2));
5103 }
5107 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5108 as above. */
5110 OEP_ONLY_CONST)
5114 OEP_ONLY_CONST))
5115 {
5118 arg2));
5121 }
5125 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5126 MAX_EXPR, to preserve the signedness of the comparison. */
5128 OEP_ONLY_CONST)
5132 OEP_ONLY_CONST))
5133 {
5136 arg2));
5138 }
5142 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5144 OEP_ONLY_CONST)
5148 OEP_ONLY_CONST))
5149 {
5152 arg2));
5154 }
5160 }
5163 }
5166 \f
5167 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5168 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5169 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5170 false) >= 2)
5171 #endif
5173 /* EXP is some logical combination of boolean tests. See if we can
5174 merge it into some range test. Return the new tree if so. */
5176 static tree
5179 {
5195 /* If this is an OR operation, invert both sides; we will invert
5196 again at the end. */
5200 /* If both expressions are the same, if we can merge the ranges, and we
5201 can build the range test, return it or it inverted. If one of the
5202 ranges is always true or always false, consider it to be the same
5203 expression as the other. */
5211 {
5215 }
5217 /* On machines where the branch cost is expensive, if this is a
5218 short-circuited branch and the underlying object on both sides
5219 is the same, make a non-short-circuit operation. */
5225 {
5226 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5227 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5228 which cases we can't do this. */
5236 {
5245 {
5248 WARN_STRICT_OVERFLOW_COMPARISON);
5252 }
5253 }
5254 }
5257 }
5258 \f
5259 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5260 bit value. Arrange things so the extra bits will be set to zero if and
5261 only if C is signed-extended to its full width. If MASK is nonzero,
5262 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5264 static tree
5266 {
5269 tree temp;
5274 /* We work by getting just the sign bit into the low-order bit, then
5275 into the high-order bit, then sign-extend. We then XOR that value
5276 with C. */
5279 /* We must use a signed type in order to get an arithmetic right shift.
5280 However, we must also avoid introducing accidental overflows, so that
5281 a subsequent call to integer_zerop will work. Hence we must
5282 do the type conversion here. At this point, the constant is either
5283 zero or one, and the conversion to a signed type can never overflow.
5284 We could get an overflow if this conversion is done anywhere else. */
5293 /* If necessary, convert the type back to match the type of C. */
5298 }
5299 \f
5300 /* For an expression that has the form
5301 (A && B) || ~B
5302 or
5303 (A || B) && ~B,
5304 we can drop one of the inner expressions and simplify to
5305 A || ~B
5306 or
5307 A && ~B
5308 LOC is the location of the resulting expression. OP is the inner
5309 logical operation; the left-hand side in the examples above, while CMPOP
5310 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5311 removing a condition that guards another, as in
5312 (A != NULL && A->...) || A == NULL
5313 which we must not transform. If RHS_ONLY is true, only eliminate the
5314 right-most operand of the inner logical operation. */
5316 static tree
5319 {
5337 {
5340 {
5343 }
5344 }
5346 {
5349 {
5352 }
5353 }
5368 }
5370 /* Find ways of folding logical expressions of LHS and RHS:
5371 Try to merge two comparisons to the same innermost item.
5372 Look for range tests like "ch >= '0' && ch <= '9'".
5373 Look for combinations of simple terms on machines with expensive branches
5374 and evaluate the RHS unconditionally.
5376 For example, if we have p->a == 2 && p->b == 4 and we can make an
5377 object large enough to span both A and B, we can do this with a comparison
5378 against the object ANDed with the a mask.
5380 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5381 operations to do this with one comparison.
5383 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5384 function and the one above.
5386 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5387 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5389 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5390 two operands.
5392 We return the simplified tree or 0 if no optimization is possible. */
5394 static tree
5397 {
5398 /* If this is the "or" of two comparisons, we can do something if
5399 the comparisons are NE_EXPR. If this is the "and", we can do something
5400 if the comparisons are EQ_EXPR. I.e.,
5401 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5403 WANTED_CODE is this operation code. For single bit fields, we can
5404 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5405 comparison for one-bit fields. */
5425 /* Start by getting the comparison codes. Fail if anything is volatile.
5426 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5427 it were surrounded with a NE_EXPR. */
5436 {
5440 }
5443 {
5447 }
5458 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5461 {
5464 {
5469 }
5472 {
5478 }
5479 }
5484 /* If the RHS can be evaluated unconditionally and its operands are
5485 simple, it wins to evaluate the RHS unconditionally on machines
5486 with expensive branches. In this case, this isn't a comparison
5487 that can be merged. */
5494 {
5495 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5506 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5516 }
5518 /* See if the comparisons can be merged. Then get all the parameters for
5519 each side. */
5543 /* It must be true that the inner operation on the lhs of each
5544 comparison must be the same if we are to be able to do anything.
5545 Then see if we have constants. If not, the same must be true for
5546 the rhs's. */
5557 else
5560 /* If either comparison code is not correct for our logical operation,
5561 fail. However, we can convert a one-bit comparison against zero into
5562 the opposite comparison against that bit being set in the field. */
5566 {
5568 {
5569 /* Make the left operand unsigned, since we are only interested
5570 in the value of one bit. Otherwise we are doing the wrong
5571 thing below. */
5574 }
5575 else
5577 }
5579 /* This is analogous to the code for l_const above. */
5581 {
5583 {
5586 }
5587 else
5589 }
5591 /* See if we can find a mode that contains both fields being compared on
5592 the left. If we can't, fail. Otherwise, update all constants and masks
5593 to be relative to a field of that size. */
5598 volatilep);
5608 {
5611 }
5619 {
5626 {
5630 }
5631 }
5633 {
5640 {
5644 }
5645 }
5647 /* If the right sides are not constant, do the same for it. Also,
5648 disallow this optimization if a size or signedness mismatch occurs
5649 between the left and right sides. */
5651 {
5654 /* Make sure the two fields on the right
5655 correspond to the left without being swapped. */
5663 volatilep);
5673 {
5676 }
5685 /* Make a mask that corresponds to both fields being compared.
5686 Do this for both items being compared. If the operands are the
5687 same size and the bits being compared are in the same position
5688 then we can do this by masking both and comparing the masked
5689 results. */
5693 {
5705 }
5707 /* There is still another way we can do something: If both pairs of
5708 fields being compared are adjacent, we may be able to make a wider
5709 field containing them both.
5711 Note that we still must mask the lhs/rhs expressions. Furthermore,
5712 the mask must be shifted to account for the shift done by
5713 make_bit_field_ref. */
5718 {
5719 tree type;
5733 /* Convert to the smaller type before masking out unwanted bits. */
5736 {
5738 {
5742 }
5744 {
5748 }
5749 }
5758 }
5761 }
5763 /* Handle the case of comparisons with constants. If there is something in
5764 common between the masks, those bits of the constants must be the same.
5765 If not, the condition is always false. Test for this to avoid generating
5766 incorrect code below. */
5771 {
5773 {
5776 }
5777 else
5778 {
5781 }
5782 }
5784 /* Construct the expression we will return. First get the component
5785 reference we will make. Unless the mask is all ones the width of
5786 that field, perform the mask operation. Then compare with the
5787 merged constant. */
5797 }
5798 \f
5799 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5800 constant. */
5802 static tree
5805 {
5808 tree comp_const;
5809 tree minmax_const;
5811 tree inner;
5822 /* If something does not permit us to optimize, return the original tree. */
5830 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5831 and GT_EXPR, doing the rest with recursive calls using logical
5832 simplifications. */
5834 {
5836 {
5837 tree tem
5844 }
5847 return
5849 optimize_minmax_comparison
5851 optimize_minmax_comparison
5856 /* MAX (X, 0) == 0 -> X <= 0 */
5860 /* MAX (X, 0) == 5 -> X == 5 */
5864 /* MAX (X, 0) == -1 -> false */
5868 /* MIN (X, 0) == 0 -> X >= 0 */
5872 /* MIN (X, 0) == 5 -> false */
5875 else
5876 /* MIN (X, 0) == -1 -> X == -1 */
5881 /* MAX (X, 0) > 0 -> X > 0
5882 MAX (X, 0) > 5 -> X > 5 */
5886 /* MAX (X, 0) > -1 -> true */
5890 /* MIN (X, 0) > 0 -> false
5891 MIN (X, 0) > 5 -> false */
5894 else
5895 /* MIN (X, 0) > -1 -> X > -1 */
5900 }
5901 }
5902 \f
5903 /* T is an integer expression that is being multiplied, divided, or taken a
5904 modulus (CODE says which and what kind of divide or modulus) by a
5905 constant C. See if we can eliminate that operation by folding it with
5906 other operations already in T. WIDE_TYPE, if non-null, is a type that
5907 should be used for the computation if wider than our type.
5909 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5910 (X * 2) + (Y * 4). We must, however, be assured that either the original
5911 expression would not overflow or that overflow is undefined for the type
5912 in the language in question.
5914 If we return a non-null expression, it is an equivalent form of the
5915 original computation, but need not be in the original type.
5917 We set *STRICT_OVERFLOW_P to true if the return values depends on
5918 signed overflow being undefined. Otherwise we do not change
5919 *STRICT_OVERFLOW_P. */
5921 static tree
5924 {
5925 /* To avoid exponential search depth, refuse to allow recursion past
5926 three levels. Beyond that (1) it's highly unlikely that we'll find
5927 something interesting and (2) we've probably processed it before
5928 when we built the inner expression. */
5931 tree ret;
5936 depth++;
5938 depth--;
5941 }
5943 static tree
5946 {
5957 /* Don't deal with constants of zero here; they confuse the code below. */
5967 /* Note that we need not handle conditional operations here since fold
5968 already handles those cases. So just do arithmetic here. */
5970 {
5972 /* For a constant, we can always simplify if we are a multiply
5973 or (for divide and modulus) if it is a multiple of our constant. */
5981 /* If op0 is an expression ... */
5987 /* ... and has wrapping overflow, and its type is smaller
5988 than ctype, then we cannot pass through as widening. */
5993 /* ... or this is a truncation (t is narrower than op0),
5994 then we cannot pass through this narrowing. */
5997 /* ... or signedness changes for division or modulus,
5998 then we cannot pass through this conversion. */
6002 /* ... or has undefined overflow while the converted to
6003 type has not, we cannot do the operation in the inner type
6004 as that would introduce undefined overflow. */
6010 /* Pass the constant down and see if we can make a simplification. If
6011 we can, replace this expression with the inner simplification for
6012 possible later conversion to our or some other type. */
6017 code == MULT_EXPR
6019 strict_overflow_p))))
6024 /* If widening the type changes it from signed to unsigned, then we
6025 must avoid building ABS_EXPR itself as unsigned. */
6027 {
6031 {
6034 }
6036 }
6037 /* If the constant is negative, we cannot simplify this. */
6040 /* FALLTHROUGH */
6042 /* For division and modulus, type can't be unsigned, as e.g.
6043 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6044 For signed types, even with wrapping overflow, this is fine. */
6053 /* If widening the type changes the signedness, then we can't perform
6054 this optimization as that changes the result. */
6058 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6064 {
6071 }
6075 /* If the second operand is constant, this is a multiplication
6076 or floor division, by a power of two, so we can treat it that
6077 way unless the multiplier or divisor overflows. Signed
6078 left-shift overflow is implementation-defined rather than
6079 undefined in C90, so do not convert signed left shift into
6080 multiplication. */
6083 /* const_binop may not detect overflow correctly,
6084 so check for it explicitly here. */
6088 size_one_node,
6089 op1)))
6093 ctype,
6095 t1),
6100 /* See if we can eliminate the operation on both sides. If we can, we
6101 can return a new PLUS or MINUS. If we can't, the only remaining
6102 cases where we can do anything are if the second operand is a
6103 constant. */
6109 /* If not multiplication, we can only do this if both operands
6110 are divisible by c. */
6113 {
6118 }
6120 /* If this was a subtraction, negate OP1 and set it to be an addition.
6121 This simplifies the logic below. */
6123 {
6125 /* If OP1 was not easily negatable, the constant may be OP0. */
6127 {
6130 }
6131 }
6136 /* If either OP1 or C are negative, this optimization is not safe for
6137 some of the division and remainder types while for others we need
6138 to change the code. */
6140 {
6148 }
6150 /* If it's a multiply or a division/modulus operation of a multiple
6151 of our constant, do the operation and verify it doesn't overflow. */
6154 {
6157 /* We allow the constant to overflow with wrapping semantics. */
6161 }
6162 else
6165 /* If we have an unsigned type, we cannot widen the operation since it
6166 will change the result if the original computation overflowed. */
6170 /* If we were able to eliminate our operation from the first side,
6171 apply our operation to the second side and reform the PLUS. */
6175 /* The last case is if we are a multiply. In that case, we can
6176 apply the distributive law to commute the multiply and addition
6177 if the multiplication of the constants doesn't overflow
6178 and overflow is defined. With undefined overflow
6179 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6185 op1);
6190 /* We have a special case here if we are doing something like
6191 (C * 8) % 4 since we know that's zero. */
6194 /* If the multiplication can overflow we cannot optimize this. */
6198 {
6201 }
6203 /* ... fall through ... */
6207 /* If we can extract our operation from the LHS, do so and return a
6208 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6209 do something only if the second operand is a constant. */
6223 /* If these are the same operation types, we can associate them
6224 assuming no overflow. */
6226 {
6238 }
6240 /* If these operations "cancel" each other, we have the main
6241 optimizations of this pass, which occur when either constant is a
6242 multiple of the other, in which case we replace this with either an
6243 operation or CODE or TCODE.
6245 If we have an unsigned type, we cannot do this since it will change
6246 the result if the original computation overflowed. */
6253 {
6255 {
6262 }
6264 {
6271 }
6272 }
6277 }
6280 }
6281 \f
6282 /* Return a node which has the indicated constant VALUE (either 0 or
6283 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6284 and is of the indicated TYPE. */
6286 tree
6288 {
6297 else
6299 }
6302 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6303 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6304 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6305 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6306 COND is the first argument to CODE; otherwise (as in the example
6307 given here), it is the second argument. TYPE is the type of the
6308 original expression. Return NULL_TREE if no simplification is
6309 possible. */
6311 static tree
6316 {
6326 {
6330 /* If this operand throws an expression, then it does not make
6331 sense to try to perform a logical or arithmetic operation
6332 involving it. */
6337 }
6338 else
6339 {
6344 }
6349 /* This transformation is only worthwhile if we don't have to wrap ARG
6350 in a SAVE_EXPR and the operation can be simplified without recursing
6351 on at least one of the branches once its pushed inside the COND_EXPR. */
6360 {
6364 else
6366 }
6368 {
6372 else
6374 }
6376 /* Check that we have simplified at least one of the branches. */
6381 }
6383 \f
6384 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6386 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6387 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6388 ADDEND is the same as X.
6390 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6391 and finite. The problematic cases are when X is zero, and its mode
6392 has signed zeros. In the case of rounding towards -infinity,
6393 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6394 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6396 bool
6398 {
6402 /* Don't allow the fold with -fsignaling-nans. */
6406 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6410 /* In a vector or complex, we would need to check the sign of all zeros. */
6414 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6418 /* The mode has signed zeros, and we have to honor their sign.
6419 In this situation, there is only one case we can return true for.
6420 X - 0 is the same as X unless rounding towards -infinity is
6421 supported. */
6423 }
6425 /* Subroutine of fold() that checks comparisons of built-in math
6426 functions against real constants.
6428 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6429 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6430 is the type of the result and ARG0 and ARG1 are the operands of the
6431 comparison. ARG1 must be a TREE_REAL_CST.
6433 The function returns the constant folded tree if a simplification
6434 can be made, and NULL_TREE otherwise. */
6436 static tree
6440 {
6441 REAL_VALUE_TYPE c;
6444 {
6450 {
6451 /* sqrt(x) < y is always false, if y is negative. */
6455 /* sqrt(x) > y is always true, if y is negative and we
6456 don't care about NaNs, i.e. negative values of x. */
6460 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6463 }
6465 {
6466 REAL_VALUE_TYPE c2;
6472 {
6473 /* sqrt(x) > y is x == +Inf, when y is very large. */
6478 /* sqrt(x) > y is always false, when y is very large
6479 and we don't care about infinities. */
6481 }
6483 /* sqrt(x) > c is the same as x > c*c. */
6486 }
6488 {
6489 REAL_VALUE_TYPE c2;
6495 {
6496 /* sqrt(x) < y is always true, when y is a very large
6497 value and we don't care about NaNs or Infinities. */
6501 /* sqrt(x) < y is x != +Inf when y is very large and we
6502 don't care about NaNs. */
6507 /* sqrt(x) < y is x >= 0 when y is very large and we
6508 don't care about Infinities. */
6513 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6518 dconst0)),
6521 c2)));
6522 }
6524 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6529 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6534 dconst0)),
6537 c2)));
6538 }
6539 }
6542 }
6544 /* Subroutine of fold() that optimizes comparisons against Infinities,
6545 either +Inf or -Inf.
6547 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6548 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6549 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6551 The function returns the constant folded tree if a simplification
6552 can be made, and NULL_TREE otherwise. */
6554 static tree
6557 {
6558 machine_mode mode;
6559 REAL_VALUE_TYPE max;
6560 tree temp;
6565 /* For negative infinity swap the sense of the comparison. */
6571 {
6573 /* x > +Inf is always false, if with ignore sNANs. */
6579 /* x <= +Inf is always true, if we don't case about NaNs. */
6583 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6589 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6595 /* x < +Inf is always equal to x <= DBL_MAX. */
6601 /* x != +Inf is always equal to !(x > DBL_MAX). */
6613 }
6616 }
6618 /* Subroutine of fold() that optimizes comparisons of a division by
6619 a nonzero integer constant against an integer constant, i.e.
6620 X/C1 op C2.
6622 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6623 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6624 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6626 The function returns the constant folded tree if a simplification
6627 can be made, and NULL_TREE otherwise. */
6629 static tree
6632 {
6640 /* We have to do this the hard way to detect unsigned overflow.
6641 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6647 {
6652 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6656 }
6658 {
6662 {
6681 }
6682 }
6683 else
6684 {
6685 /* A negative divisor reverses the relational operators. */
6691 {
6710 }
6711 }
6714 {
6735 {
6738 }
6743 {
6746 }
6751 {
6754 }
6759 {
6762 }
6767 }
6770 }
6773 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6774 equality/inequality test, then return a simplified form of the test
6775 using a sign testing. Otherwise return NULL. TYPE is the desired
6776 result type. */
6778 static tree
6781 tree result_type)
6782 {
6783 /* If this is testing a single bit, we can optimize the test. */
6787 {
6788 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6789 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6793 /* This is only a win if casting to a signed type is cheap,
6794 i.e. when arg00's type is not a partial mode. */
6797 {
6800 result_type,
6803 }
6804 }
6807 }
6809 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6810 equality/inequality test, then return a simplified form of
6811 the test using shifts and logical operations. Otherwise return
6812 NULL. TYPE is the desired result type. */
6814 tree
6817 {
6818 /* If this is testing a single bit, we can optimize the test. */
6822 {
6831 /* First, see if we can fold the single bit test into a sign-bit
6832 test. */
6834 result_type);
6838 /* Otherwise we have (A & C) != 0 where C is a single bit,
6839 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6840 Similarly for (A & C) == 0. */
6842 /* If INNER is a right shift of a constant and it plus BITNUM does
6843 not overflow, adjust BITNUM and INNER. */
6849 {
6852 }
6854 /* If we are going to be able to omit the AND below, we must do our
6855 operations as unsigned. If we must use the AND, we have a choice.
6856 Normally unsigned is faster, but for some machines signed is. */
6857 #ifdef LOAD_EXTEND_OP
6860 #else
6862 #endif
6878 /* Put the AND last so it can combine with more things. */
6881 /* Make sure to return the proper type. */
6885 }
6887 }
6889 /* Check whether we are allowed to reorder operands arg0 and arg1,
6890 such that the evaluation of arg1 occurs before arg0. */
6892 static bool
6894 {
6901 }
6903 /* Test whether it is preferable two swap two operands, ARG0 and
6904 ARG1, for example because ARG0 is an integer constant and ARG1
6905 isn't. If REORDER is true, only recommend swapping if we can
6906 evaluate the operands in reverse order. */
6908 bool
6910 {
6928 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6929 for commutative and comparison operators. Ensuring a canonical
6930 form allows the optimizers to find additional redundancies without
6931 having to explicitly check for both orderings. */
6937 /* Put SSA_NAMEs last. */
6943 /* Put variables last. */
6950 }
6952 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6953 ARG0 is extended to a wider type. */
6955 static tree
6958 {
6960 tree arg1_unw;
6969 #ifdef HAVE_canonicalize_funcptr_for_compare
6970 /* Disable this optimization if we're casting a function pointer
6971 type on targets that require function pointer canonicalization. */
6976 #endif
6983 /* If possible, express the comparison in the shorter mode. */
7003 /* If we are comparing with the integer that does not fit into the range
7004 of the shorter type, the result is known. */
7015 {
7042 }
7045 }
7047 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7048 ARG0 just the signedness is changed. */
7050 static tree
7053 {
7054 tree arg0_inner;
7064 #ifdef HAVE_canonicalize_funcptr_for_compare
7065 /* Disable this optimization if we're casting a function pointer
7066 type on targets that require function pointer canonicalization. */
7071 #endif
7092 else
7096 }
7099 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7100 means A >= Y && A != MAX, but in this case we know that
7101 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7103 static tree
7105 {
7112 else
7121 {
7124 }
7126 {
7129 }
7130 else
7137 {
7138 /* Convert the pointer types into integer before taking the difference. */
7142 }
7143 else
7150 }
7152 /* Fold a sum or difference of at least one multiplication.
7153 Returns the folded tree or NULL if no simplification could be made. */
7155 static tree
7158 {
7162 /* (A * C) +- (B * C) -> (A+-B) * C.
7163 (A * C) +- A -> A * (C+-1).
7164 We are most concerned about the case where C is a constant,
7165 but other combinations show up during loop reduction. Since
7166 it is not difficult, try all four possibilities. */
7169 {
7172 }
7174 {
7177 }
7178 else
7179 {
7180 /* We cannot generate constant 1 for fract. */
7185 }
7187 {
7190 }
7192 {
7194 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7195 the purpose of this canonicalization. */
7199 {
7202 }
7203 else
7205 }
7206 else
7207 {
7208 /* We cannot generate constant 1 for fract. */
7213 }
7225 /* No identical multiplicands; see if we can find a common
7226 power-of-two factor in non-power-of-two multiplies. This
7227 can help in multi-dimensional array access. */
7230 {
7233 tree maybe_same;
7237 /* Move min of absolute values to int11. */
7239 {
7244 }
7245 else
7249 /* The remainder should not be a constant, otherwise we
7250 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7251 increased the number of multiplications necessary. */
7253 {
7261 }
7262 }
7272 }
7274 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7275 specified by EXPR into the buffer PTR of length LEN bytes.
7276 Return the number of bytes placed in the buffer, or zero
7277 upon failure. */
7279 static int
7281 {
7295 {
7297 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7298 number of bytes. */
7302 {
7309 else
7311 }
7312 else
7317 }
7319 }
7322 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7323 specified by EXPR into the buffer PTR of length LEN bytes.
7324 Return the number of bytes placed in the buffer, or zero
7325 upon failure. */
7327 static int
7329 {
7333 FIXED_VALUE_TYPE value;
7349 }
7352 /* Subroutine of native_encode_expr. Encode the REAL_CST
7353 specified by EXPR into the buffer PTR of length LEN bytes.
7354 Return the number of bytes placed in the buffer, or zero
7355 upon failure. */
7357 static int
7359 {
7365 /* There are always 32 bits in each long, no matter the size of
7366 the hosts long. We handle floating point representations with
7367 up to 192 bits. */
7381 {
7386 {
7393 else
7395 }
7396 else
7402 }
7404 }
7406 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7407 specified by EXPR into the buffer PTR of length LEN bytes.
7408 Return the number of bytes placed in the buffer, or zero
7409 upon failure. */
7411 static int
7413 {
7415 tree part;
7430 }
7433 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7434 specified by EXPR into the buffer PTR of length LEN bytes.
7435 Return the number of bytes placed in the buffer, or zero
7436 upon failure. */
7438 static int
7440 {
7450 {
7452 {
7455 }
7466 }
7468 }
7471 /* Subroutine of native_encode_expr. Encode the STRING_CST
7472 specified by EXPR into the buffer PTR of length LEN bytes.
7473 Return the number of bytes placed in the buffer, or zero
7474 upon failure. */
7476 static int
7478 {
7480 HOST_WIDE_INT total_bytes;
7494 {
7497 {
7500 }
7503 }
7504 else
7507 }
7510 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7511 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7512 buffer PTR of length LEN bytes. If OFF is not -1 then start
7513 the encoding at byte offset OFF and encode at most LEN bytes.
7514 Return the number of bytes placed in the buffer, or zero upon failure. */
7516 int
7518 {
7520 {
7541 }
7542 }
7545 /* Subroutine of native_interpret_expr. Interpret the contents of
7546 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7547 If the buffer cannot be interpreted, return NULL_TREE. */
7549 static tree
7551 {
7561 }
7564 /* Subroutine of native_interpret_expr. Interpret the contents of
7565 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7566 If the buffer cannot be interpreted, return NULL_TREE. */
7568 static tree
7570 {
7572 double_int result;
7573 FIXED_VALUE_TYPE fixed_value;
7583 }
7586 /* Subroutine of native_interpret_expr. Interpret the contents of
7587 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7588 If the buffer cannot be interpreted, return NULL_TREE. */
7590 static tree
7592 {
7597 /* There are always 32 bits in each long, no matter the size of
7598 the hosts long. We handle floating point representations with
7599 up to 192 bits. */
7600 REAL_VALUE_TYPE r;
7611 {
7614 {
7621 else
7623 }
7624 else
7629 }
7633 }
7636 /* Subroutine of native_interpret_expr. Interpret the contents of
7637 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7638 If the buffer cannot be interpreted, return NULL_TREE. */
7640 static tree
7642 {
7657 }
7660 /* Subroutine of native_interpret_expr. Interpret the contents of
7661 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7662 If the buffer cannot be interpreted, return NULL_TREE. */
7664 static tree
7666 {
7679 {
7684 }
7686 }
7689 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7690 the buffer PTR of length LEN as a constant of type TYPE. For
7691 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7692 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7693 return NULL_TREE. */
7695 tree
7697 {
7699 {
7721 }
7722 }
7724 /* Returns true if we can interpret the contents of a native encoding
7725 as TYPE. */
7727 static bool
7729 {
7731 {
7744 }
7745 }
7747 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7748 TYPE at compile-time. If we're unable to perform the conversion
7749 return NULL_TREE. */
7751 static tree
7753 {
7754 /* We support up to 512-bit values (for V8DFmode). */
7758 /* Check that the host and target are sane. */
7767 }
7769 /* Build an expression for the address of T. Folds away INDIRECT_REF
7770 to avoid confusing the gimplify process. */
7772 tree
7774 {
7775 /* The size of the object is not relevant when talking about its address. */
7780 {
7785 }
7795 {
7800 }
7801 else
7805 }
7807 /* Build an expression for the address of T. */
7809 tree
7811 {
7815 }
7817 /* Fold a unary expression of code CODE and type TYPE with operand
7818 OP0. Return the folded expression if folding is successful.
7819 Otherwise, return NULL_TREE. */
7821 tree
7823 {
7824 tree tem;
7825 tree arg0;
7833 {
7836 {
7837 /* Don't use STRIP_NOPS, because signedness of argument type
7838 matters. */
7840 }
7841 else
7842 {
7843 /* Strip any conversions that don't change the mode. This
7844 is safe for every expression, except for a comparison
7845 expression because its signedness is derived from its
7846 operands.
7848 Note that this is done as an internal manipulation within
7849 the constant folder, in order to find the simplest
7850 representation of the arguments so that their form can be
7851 studied. In any cases, the appropriate type conversions
7852 should be put back in the tree that will get out of the
7853 constant folder. */
7855 }
7858 {
7861 {
7865 }
7866 }
7867 }
7874 {
7881 {
7895 /* If this was a conversion, and all we did was to move into
7896 inside the COND_EXPR, bring it back out. But leave it if
7897 it is a conversion from integer to integer and the
7898 result precision is no wider than a word since such a
7899 conversion is cheap and may be optimized away by combine,
7900 while it couldn't if it were outside the COND_EXPR. Then return
7901 so we don't get into an infinite recursion loop taking the
7902 conversion out and then back in. */
7914 && (INTEGRAL_TYPE_P
7927 }
7928 }
7931 {
7937 CASE_CONVERT:
7941 {
7942 /* If we have (type) (a CMP b) and type is an integral type, return
7943 new expression involving the new type. Canonicalize
7944 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7945 non-integral type.
7946 Do not fold the result as that would not simplify further, also
7947 folding again results in recursions. */
7957 }
7959 /* Handle (T *)&A.B.C for A being of type T and B and C
7960 living at offset zero. This occurs frequently in
7961 C++ upcasting and then accessing the base. */
7965 {
7967 tree offset;
7968 machine_mode mode;
7973 /* If the reference was to a (constant) zero offset, we can use
7974 the address of the base if it has the same base type
7975 as the result type and the pointer type is unqualified. */
7982 }
7986 /* Detect assigning a bitfield. */
7988 && DECL_BIT_FIELD
7990 {
7991 /* Don't leave an assignment inside a conversion
7992 unless assigning a bitfield. */
7994 /* First do the assignment, then return converted constant. */
7999 }
8001 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
8002 constants (if x has signed type, the sign bit cannot be set
8003 in c). This folds extension into the BIT_AND_EXPR.
8004 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
8005 very likely don't have maximal range for their precision and this
8006 transformation effectively doesn't preserve non-maximal ranges. */
8010 {
8021 <= HOST_BITS_PER_WIDE_INT
8023 {
8027 cst &= HOST_WIDE_INT_M1U
8030 #ifdef LOAD_EXTEND_OP
8032 && !flag_syntax_only
8035 {
8039 }
8040 #endif
8041 }
8043 {
8048 }
8049 }
8051 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8052 when one of the new casts will fold away. Conservatively we assume
8053 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8060 {
8064 return fold_build_pointer_plus_loc
8066 }
8068 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8069 of the same precision, and X is an integer type not narrower than
8070 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8076 {
8082 }
8084 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8085 type of X and Y (integer types only). */
8090 {
8091 /* Be careful not to introduce new overflows. */
8092 tree mult_type;
8095 else
8099 {
8106 }
8107 }
8125 /* Convert fabs((double)float) into (double)fabsf(float). */
8128 {
8134 targ0));
8135 }
8136 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8140 /* Strip sign ops from argument. */
8142 {
8147 }
8154 {
8160 }
8166 /* Convert ~ (-A) to A - 1. */
8171 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8177 {
8178 /* Perform the negation in ARG0's type and only then convert
8179 to TYPE as to avoid introducing undefined behavior. */
8184 }
8185 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8204 /* Note that the operand of this must be an int
8205 and its values must be 0 or 1.
8206 ("true" is a fixed value perhaps depending on the language,
8207 but we don't handle values other than 1 correctly yet.) */
8217 {
8225 }
8227 {
8232 }
8234 {
8238 {
8247 }
8248 }
8255 {
8263 }
8265 {
8269 }
8271 {
8275 {
8284 }
8285 }
8289 /* Fold *&X to X if X is an lvalue. */
8291 {
8298 }
8304 }
8307 /* If the operation was a conversion do _not_ mark a resulting constant
8308 with TREE_OVERFLOW if the original constant was not. These conversions
8309 have implementation defined behavior and retaining the TREE_OVERFLOW
8310 flag here would confuse later passes such as VRP. */
8311 tree
8314 {
8323 }
8325 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8326 operands OP0 and OP1. LOC is the location of the resulting expression.
8327 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8328 Return the folded expression if folding is successful. Otherwise,
8329 return NULL_TREE. */
8330 static tree
8333 {
8334 tree tem;
8336 /* We only do these simplifications if we are optimizing. */
8340 /* Check for things like (A || B) && (A || C). We can convert this
8341 to A || (B && C). Note that either operator can be any of the four
8342 truth and/or operations and the transformation will still be
8343 valid. Also note that we only care about order for the
8344 ANDIF and ORIF operators. If B contains side effects, this
8345 might change the truth-value of A. */
8352 {
8372 /* This case if tricky because we must either have commutative
8373 operators or else A10 must not have side-effects. */
8379 a01);
8380 }
8382 /* See if we can build a range comparison. */
8388 {
8392 }
8396 {
8400 }
8402 /* Check for the possibility of merging component references. If our
8403 lhs is another similar operation, try to merge its rhs with our
8404 rhs. Then try to merge our lhs and rhs. */
8418 {
8425 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8426 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8427 We don't want to pack more than two leafs to a non-IF AND/OR
8428 expression.
8429 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8430 equal to IF-CODE, then we don't want to add right-hand operand.
8431 If the inner right-hand side of left-hand operand has
8432 side-effects, or isn't simple, then we can't add to it,
8433 as otherwise we might destroy if-sequence. */
8436 /* Needed for sequence points to handle trappings, and
8437 side-effects. */
8439 {
8441 arg1);
8443 tem);
8444 }
8445 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8446 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8449 /* Needed for sequence points to handle trappings, and
8450 side-effects. */
8452 {
8457 }
8458 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8459 into (A OR B).
8460 For sequence point consistancy, we need to check for trapping,
8461 and side-effects. */
8465 }
8468 }
8470 /* Fold a binary expression of code CODE and type TYPE with operands
8471 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8472 Return the folded expression if folding is successful. Otherwise,
8473 return NULL_TREE. */
8475 static tree
8477 {
8484 else
8487 /* MIN (MAX (a, b), b) == b. */
8492 /* MIN (MAX (b, a), b) == b. */
8498 /* MIN (a, MAX (a, b)) == a. */
8504 /* MIN (a, MAX (b, a)) == a. */
8511 }
8513 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8514 by changing CODE to reduce the magnitude of constants involved in
8515 ARG0 of the comparison.
8516 Returns a canonicalized comparison tree if a simplification was
8517 possible, otherwise returns NULL_TREE.
8518 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8519 valid if signed overflow is undefined. */
8521 static tree
8525 {
8531 /* Match A +- CST code arg1 and CST code arg1. We can change the
8532 first form only if overflow is undefined. */
8535 /* In principle pointers also have undefined overflow behavior,
8536 but that causes problems elsewhere. */
8544 /* Identify the constant in arg0 and its sign. */
8547 else
8551 /* Overflowed constants and zero will cause problems. */
8556 /* See if we can reduce the magnitude of the constant in
8557 arg0 by changing the comparison code. */
8559 {
8560 /* CST <= arg1 -> CST-1 < arg1. */
8563 /* -CST < arg1 -> -CST-1 <= arg1. */
8566 /* CST > arg1 -> CST-1 >= arg1. */
8569 /* -CST >= arg1 -> -CST-1 > arg1. */
8572 else
8574 /* arg1 code' CST' might be more canonical. */
8576 }
8577 else
8578 {
8579 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8583 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8587 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8591 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8595 else
8598 }
8600 /* Now build the constant reduced in magnitude. But not if that
8601 would produce one outside of its types range. */
8609 /* We cannot swap the comparison here as that would cause us to
8610 endlessly recurse. */
8619 /* If swapping might yield to a more canonical form, do so. */
8622 else
8624 }
8626 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8627 overflow further. Try to decrease the magnitude of constants involved
8628 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8629 and put sole constants at the second argument position.
8630 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8632 static tree
8635 {
8636 tree t;
8641 /* Try canonicalization by simplifying arg0. */
8646 {
8650 }
8652 /* Try canonicalization by simplifying arg1 using the swapped
8653 comparison. */
8661 }
8663 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8664 space. This is used to avoid issuing overflow warnings for
8665 expressions like &p->x which can not wrap. */
8667 static bool
8669 {
8676 wide_int wi_offset;
8682 else
8698 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8699 array. */
8701 {
8702 HOST_WIDE_INT base_size;
8707 }
8710 }
8712 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8713 kind INTEGER_CST. This makes sure to properly sign-extend the
8714 constant. */
8716 static HOST_WIDE_INT
8718 {
8724 }
8726 /* Subroutine of fold_binary. This routine performs all of the
8727 transformations that are common to the equality/inequality
8728 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8729 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8730 fold_binary should call fold_binary. Fold a comparison with
8731 tree code CODE and type TYPE with operands OP0 and OP1. Return
8732 the folded comparison or NULL_TREE. */
8734 static tree
8737 {
8747 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8749 && (equality_code
8756 {
8757 const enum tree_code
8764 /* If the constant operation overflowed this can be
8765 simplified as a comparison against INT_MAX/INT_MIN. */
8768 {
8772 /* Get the sign of the constant on the lhs if the
8773 operation were VARIABLE + CONST1. */
8777 /* The sign of the constant determines if we overflowed
8778 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8779 Canonicalize to the INT_MIN overflow by swapping the comparison
8780 if necessary. */
8784 /* We now can look at the canonicalized case
8785 VARIABLE + 1 CODE2 INT_MIN
8786 and decide on the result. */
8788 {
8792 return
8798 return
8803 }
8804 }
8805 else
8806 {
8809 "when changing X +- C1 cmp C2 to "
8811 WARN_STRICT_OVERFLOW_COMPARISON);
8813 }
8814 }
8816 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8818 && equality_code
8820 {
8821 /* ??? The transformation is valid for the other operators if overflow
8822 is undefined for the type, but performing it here badly interacts
8823 with the transformation in fold_cond_expr_with_comparison which
8824 attempts to synthetize ABS_EXPR. */
8828 WARN_STRICT_OVERFLOW_COMPARISON);
8831 }
8833 /* For comparisons of pointers we can decompose it to a compile time
8834 comparison of the base objects and the offsets into the object.
8835 This requires at least one operand being an ADDR_EXPR or a
8836 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8842 {
8845 machine_mode mode;
8849 /* Get base and offset for the access. Strip ADDR_EXPR for
8850 get_inner_reference, but put it back by stripping INDIRECT_REF
8851 off the base object if possible. indirect_baseN will be true
8852 if baseN is not an address but refers to the object itself. */
8855 {
8861 else
8863 }
8865 {
8869 {
8872 }
8875 {
8880 {
8883 }
8884 }
8885 }
8889 {
8895 else
8897 }
8899 {
8903 {
8906 }
8909 {
8914 {
8917 }
8918 }
8919 }
8921 /* A local variable can never be pointed to by
8922 the default SSA name of an incoming parameter. */
8924 && indirect_base0
8927 && !indirect_base1
8932 && indirect_base1
8935 && !indirect_base0
8939 {
8944 }
8945 /* If we have equivalent bases we might be able to simplify. */
8948 {
8949 /* We can fold this expression to a constant if the non-constant
8950 offset parts are equal. */
8959 {
8965 "occur when comparing P +- C1 with "
8967 WARN_STRICT_OVERFLOW_CONDITIONAL);
8970 {
8984 }
8985 }
8986 /* We can simplify the comparison to a comparison of the variable
8987 offset parts if the constant offset parts are equal.
8988 Be careful to use signed sizetype here because otherwise we
8989 mess with array offsets in the wrong way. This is possible
8990 because pointer arithmetic is restricted to retain within an
8991 object and overflow on pointer differences is undefined as of
8992 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8994 && (equality_code
8997 {
8998 /* By converting to signed sizetype we cover middle-end pointer
8999 arithmetic which operates on unsigned pointer types of size
9000 type size and ARRAY_REF offsets which are properly sign or
9001 zero extended from their type in case it is narrower than
9002 sizetype. */
9005 else
9009 else
9016 "occur when comparing P +- C1 with "
9018 WARN_STRICT_OVERFLOW_COMPARISON);
9021 }
9022 }
9023 /* For non-equal bases we can simplify if they are addresses
9024 declarations with different addresses. */
9026 /* We know that !operand_equal_p (base0, base1, 0)
9027 because the if condition was false. But make
9028 sure two decls are not the same. */
9034 /* Watch for aliases. */
9039 {
9046 }
9047 /* For equal offsets we can simplify to a comparison of the
9048 base addresses. */
9050 && (indirect_base0
9052 && (indirect_base1
9057 {
9063 }
9064 }
9066 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9067 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9068 the resulting offset is smaller in absolute value than the
9069 original one and has the same sign. */
9078 {
9083 tree cst;
9085 "occur when combining constants around "
9088 /* Put the constant on the side where it doesn't overflow and is
9089 of lower absolute value and of same sign than before. */
9096 {
9099 variable1,
9103 }
9111 {
9117 variable2);
9118 }
9119 }
9121 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9122 signed arithmetic case. That form is created by the compiler
9123 often enough for folding it to be of value. One example is in
9124 computing loop trip counts after Operator Strength Reduction. */
9131 {
9137 /* Handle unfolded multiplication by zero. */
9142 "eliminating multiplication in comparison "
9144 WARN_STRICT_OVERFLOW_COMPARISON);
9146 /* If const1 is negative we swap the sense of the comparison. */
9151 }
9158 {
9166 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9173 {
9174 REAL_VALUE_TYPE cst;
9177 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9178 /* a CMP (-0) -> a CMP 0 */
9183 /* x != NaN is always true, other ops are always false. */
9186 {
9189 }
9191 /* Fold comparisons against infinity. */
9194 {
9198 }
9199 }
9201 /* If this is a comparison of a real constant with a PLUS_EXPR
9202 or a MINUS_EXPR of a real constant, we can convert it into a
9203 comparison with a revised real constant as long as no overflow
9204 occurs when unsafe_math_optimizations are enabled. */
9216 /* Likewise, we can simplify a comparison of a real constant with
9217 a MINUS_EXPR whose first operand is also a real constant, i.e.
9218 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9219 floating-point types only if -fassociative-math is set. */
9225 arg1))
9230 /* Fold comparisons against built-in math functions. */
9232 && flag_unsafe_math_optimizations
9234 {
9238 {
9242 }
9243 }
9244 }
9248 {
9249 /* If we are widening one operand of an integer comparison,
9250 see if the other operand is similarly being widened. Perhaps we
9251 can do the comparison in the narrower type. */
9256 /* Or if we are changing signedness. */
9260 }
9262 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9263 constant, we can simplify it. */
9268 {
9272 }
9274 /* Simplify comparison of something with itself. (For IEEE
9275 floating-point, we can only do some of these simplifications.) */
9277 {
9279 {
9294 /* For NE, we can only do this simplification if integer
9295 or we don't honor IEEE floating point NaNs. */
9299 /* ... fall through ... */
9305 }
9306 }
9308 /* If we are comparing an expression that just has comparisons
9309 of two integer values, arithmetic expressions of those comparisons,
9310 and constants, we can simplify it. There are only three cases
9311 to check: the two values can either be equal, the first can be
9312 greater, or the second can be greater. Fold the expression for
9313 those three values. Since each value must be 0 or 1, we have
9314 eight possibilities, each of which corresponds to the constant 0
9315 or 1 or one of the six possible comparisons.
9317 This handles common cases like (a > b) == 0 but also handles
9318 expressions like ((x > y) - (y > x)) > 0, which supposedly
9319 occur in macroized code. */
9322 {
9327 /* Don't handle degenerate cases here; they should already
9328 have been handled anyway. */
9337 {
9341 /* We can't just pass T to eval_subst in case cval1 or cval2
9342 was the same as ARG1. */
9344 tree high_result
9348 arg1);
9349 tree equal_result
9353 arg1);
9354 tree low_result
9358 arg1);
9360 /* All three of these results should be 0 or 1. Confirm they are.
9361 Then use those values to select the proper code to use. */
9366 {
9367 /* Make a 3-bit mask with the high-order bit being the
9368 value for `>', the next for '=', and the low for '<'. */
9372 {
9374 /* Always false. */
9395 /* Always true. */
9397 }
9400 {
9404 }
9406 }
9407 }
9408 }
9410 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9411 into a single range test. */
9419 {
9423 }
9425 /* Fold ~X op ~Y as Y op X. */
9428 {
9434 }
9436 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9439 {
9445 }
9448 }
9451 /* Subroutine of fold_binary. Optimize complex multiplications of the
9452 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9453 argument EXPR represents the expression "z" of type TYPE. */
9455 static tree
9457 {
9462 {
9465 }
9467 {
9470 }
9471 else
9472 {
9476 }
9485 }
9488 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9489 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9490 guarantees that P and N have the same least significant log2(M) bits.
9491 N is not otherwise constrained. In particular, N is not normalized to
9492 0 <= N < M as is common. In general, the precise value of P is unknown.
9493 M is chosen as large as possible such that constant N can be determined.
9495 Returns M and sets *RESIDUE to N.
9497 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9498 account. This is not always possible due to PR 35705.
9499 */
9501 static unsigned HOST_WIDE_INT
9504 {
9511 {
9516 }
9518 {
9526 allow_func_align);
9532 {
9535 }
9537 {
9540 {
9543 /* Compute the greatest power-of-2 divisor of op1. */
9547 /* If align is non-zero and less than *modulus, replace
9548 *modulus with align., If align is 0, then either op1 is 0
9549 or the greatest power-of-2 divisor of op1 doesn't fit in an
9550 unsigned HOST_WIDE_INT. In either case, no additional
9551 constraint is imposed. */
9556 }
9557 }
9558 }
9560 /* If we get here, we were unable to determine anything useful about the
9561 expression. */
9563 }
9565 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9566 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9568 static bool
9570 {
9574 {
9577 }
9579 {
9585 else
9587 }
9588 else
9594 }
9596 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9597 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9598 NULL_TREE otherwise. */
9600 static tree
9602 {
9619 {
9623 }
9626 {
9632 }
9633 else
9635 }
9637 /* Try to fold a pointer difference of type TYPE two address expressions of
9638 array references AREF0 and AREF1 using location LOC. Return a
9639 simplified expression for the difference or NULL_TREE. */
9641 static tree
9644 {
9649 /* If the bases are array references as well, recurse. If the bases
9650 are pointer indirections compute the difference of the pointers.
9651 If the bases are equal, we are set. */
9654 && (base_offset
9662 {
9668 base_offset,
9671 }
9673 }
9675 /* If the real or vector real constant CST of type TYPE has an exact
9676 inverse, return it, else return NULL. */
9678 tree
9680 {
9681 REAL_VALUE_TYPE r;
9683 machine_mode mode;
9687 {
9703 {
9708 }
9714 }
9715 }
9717 /* Mask out the tz least significant bits of X of type TYPE where
9718 tz is the number of trailing zeroes in Y. */
9719 static wide_int
9721 {
9726 }
9728 /* Return true when T is an address and is known to be nonzero.
9729 For floating point we further ensure that T is not denormal.
9730 Similar logic is present in nonzero_address in rtlanal.h.
9732 If the return value is based on the assumption that signed overflow
9733 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9734 change *STRICT_OVERFLOW_P. */
9736 static bool
9738 {
9742 /* Doing something useful for floating point would need more work. */
9748 {
9751 strict_overflow_p);
9757 strict_overflow_p);
9765 }
9768 {
9771 strict_overflow_p);
9779 strict_overflow_p);
9794 strict_overflow_p);
9798 strict_overflow_p);
9801 {
9813 }
9817 }
9819 }
9821 /* Return true when T is an address and is known to be nonzero.
9822 Handle warnings about undefined signed overflow. */
9824 static bool
9826 {
9833 "determining that expression is always "
9835 WARN_STRICT_OVERFLOW_MISC);
9837 }
9839 /* Fold a binary expression of code CODE and type TYPE with operands
9840 OP0 and OP1. LOC is the location of the resulting expression.
9841 Return the folded expression if folding is successful. Otherwise,
9842 return NULL_TREE. */
9844 tree
9847 {
9862 /* Strip any conversions that don't change the mode. This is
9863 safe for every expression, except for a comparison expression
9864 because its signedness is derived from its operands. So, in
9865 the latter case, only strip conversions that don't change the
9866 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9867 preserved.
9869 Note that this is done as an internal manipulation within the
9870 constant folder, in order to find the simplest representation
9871 of the arguments so that their form can be studied. In any
9872 cases, the appropriate type conversions should be put back in
9873 the tree that will get out of the constant folder. */
9876 {
9879 }
9880 else
9881 {
9884 }
9886 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9887 constant but we can't do arithmetic on them. */
9889 {
9892 {
9896 }
9897 }
9899 /* If this is a commutative operation, and ARG0 is a constant, move it
9900 to ARG1 to reduce the number of tests below. */
9905 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9906 to ARG1 to reduce the number of tests below. */
9915 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9917 First check for cases where an arithmetic operation is applied to a
9918 compound, conditional, or comparison operation. Push the arithmetic
9919 operation inside the compound or conditional to see if any folding
9920 can then be done. Convert comparison to conditional for this purpose.
9921 The also optimizes non-constant cases that used to be done in
9922 expand_expr.
9924 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9925 one of the operands is a comparison and the other is a comparison, a
9926 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9927 code below would make the expression more complex. Change it to a
9928 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9929 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9942 {
9946 boolean_type_node,
9954 }
9958 {
9960 {
9965 tem);
9966 }
9969 {
9974 tem);
9975 }
9980 {
9986 }
9991 {
9997 }
9998 }
10001 {
10003 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10006 {
10012 }
10014 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10017 {
10018 tree base;
10019 HOST_WIDE_INT coffset;
10028 }
10033 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10039 arg1),
10041 arg0)));
10047 {
10048 /* X + (X / CST) * -CST is X % CST. */
10053 {
10062 cst0));
10063 }
10064 }
10066 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10067 one. Make sure the type is not saturating and has the signedness of
10068 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10069 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10076 {
10080 }
10083 {
10084 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10085 with a constant, and the two constants have no bits in common,
10086 we should treat this as a BIT_IOR_EXPR since this may produce more
10087 simplifications. */
10094 {
10097 }
10099 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10100 (plus (plus (mult) (mult)) (foo)) so that we can
10101 take advantage of the factoring cases below. */
10110 {
10116 else
10129 parg0),
10131 marg)),
10135 return
10141 parg1)));
10142 }
10143 }
10144 else
10145 {
10146 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10147 to __complex__ ( x, y ). This is not the same for SNaNs or
10148 if signed zeros are involved. */
10152 {
10159 {
10163 {
10169 }
10171 {
10177 }
10178 }
10179 }
10187 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10188 We associate floats only if the user has specified
10189 -fassociative-math. */
10193 {
10198 {
10199 tree tree0;
10202 }
10203 }
10204 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10205 We associate floats only if the user has specified
10206 -fassociative-math. */
10210 {
10215 {
10216 tree tree0;
10219 }
10220 }
10221 }
10223 bit_rotate:
10224 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10225 is a rotate of A by C1 bits. */
10226 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10227 is a rotate of A by B bits. */
10228 {
10230 tree rtype;
10239 /* Only create rotates in complete modes. Other cases are not
10240 expanded properly. */
10243 {
10257 {
10261 code0 == LSHIFT_EXPR
10265 }
10267 {
10275 element_precision
10279 return
10282 ? LROTATE_EXPR
10287 }
10289 {
10297 element_precision
10301 return fold_convert_loc
10304 ? LROTATE_EXPR
10308 }
10309 }
10310 }
10312 associate:
10313 /* In most languages, can't associate operations on floats through
10314 parentheses. Rather than remember where the parentheses were, we
10315 don't associate floats at all, unless the user has specified
10316 -fassociative-math.
10317 And, we need to make sure type is not saturating. */
10321 {
10327 /* Split both trees into variables, constants, and literals. Then
10328 associate each group together, the constants with literals,
10329 then the result with variables. This increases the chances of
10330 literals being recombined later and of generating relocatable
10331 expressions for the sum of a constant and literal. */
10336 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10340 /* With undefined overflow prefer doing association in a type
10341 which wraps on overflow, if that is one of the operand types. */
10344 {
10352 }
10354 /* With undefined overflow we can only associate constants with one
10355 variable, and constants whose association doesn't overflow. */
10358 {
10360 {
10378 /* The only case we can still associate with two variables
10379 is if they are the same, modulo negation and bit-pattern
10380 preserving conversions. */
10383 }
10384 }
10386 /* Only do something if we found more than two objects. Otherwise,
10387 nothing has changed and we risk infinite recursion. */
10393 {
10405 /* Preserve the MINUS_EXPR if the negative part of the literal is
10406 greater than the positive part. Otherwise, the multiplicative
10407 folding code (i.e extract_muldiv) may be fooled in case
10408 unsigned constants are subtracted, like in the following
10409 example: ((X*2 + 4) - 8U)/2. */
10411 {
10415 {
10419 }
10420 else
10421 {
10425 }
10426 }
10428 /* Don't introduce overflows through reassociation. */
10435 {
10437 return
10441 else
10442 {
10445 return
10449 }
10450 }
10453 return
10456 }
10457 }
10462 /* Pointer simplifications for subtraction, simple reassociations. */
10464 {
10465 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10468 {
10478 }
10479 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10481 {
10488 }
10489 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10490 simplifies. */
10492 {
10499 arg10);
10502 }
10503 }
10504 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10514 /* X - (X / Y) * Y is X % Y. */
10522 return
10528 {
10529 /* Fold A - (A & B) into ~B & A. */
10532 {
10534 {
10541 }
10543 {
10550 }
10551 }
10553 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10554 any power of 2 minus 1. */
10559 {
10565 {
10569 }
10570 }
10571 }
10573 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10574 __complex__ ( x, -y ). This is not the same for SNaNs or if
10575 signed zeros are involved. */
10579 {
10586 {
10590 {
10592 arg1r ? arg1r
10597 }
10599 {
10603 arg1i ? arg1i
10606 }
10607 }
10608 }
10610 /* A - B -> A + (-B) if B is easily negatable. */
10614 /* Avoid this transformation if B is a positive REAL_CST. */
10623 /* Try folding difference of addresses. */
10624 {
10625 HOST_WIDE_INT diff;
10631 }
10633 /* Fold &a[i] - &a[j] to i-j. */
10638 {
10644 }
10647 && flag_unsafe_math_optimizations
10653 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10654 one. Make sure the type is not saturating and has the signedness of
10655 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10656 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10663 {
10667 }
10672 /* (-A) * (-B) -> A * B */
10687 {
10688 /* Transform x * -C into -x * C if x is easily negatable. */
10697 tem);
10699 /* (a * (1 << b)) is (a << b) */
10709 /* (A + A) * C -> A * 2 * C */
10721 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10722 sign-changing only. */
10732 {
10735 "occur when simplifying "
10737 WARN_STRICT_OVERFLOW_MISC);
10739 }
10741 /* Optimize z * conj(z) for integer complex numbers. */
10748 }
10749 else
10750 {
10751 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10752 the result for floating point types due to rounding so it is applied
10753 only if -fassociative-math was specify. */
10758 {
10760 arg1);
10764 }
10766 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10768 {
10771 {
10774 }
10775 }
10777 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10778 This is not the same for NaNs or if signed zeros are
10779 involved. */
10785 {
10788 return
10794 return
10799 }
10801 /* Optimize z * conj(z) for floating point complex numbers.
10802 Guarded by flag_unsafe_math_optimizations as non-finite
10803 imaginary components don't produce scalar results. */
10814 {
10818 /* Optimizations of root(...)*root(...). */
10820 {
10825 /* Optimize sqrt(x)*sqrt(x) as x. */
10831 /* Optimize root(x)*root(y) as root(x*y). */
10835 }
10837 /* Optimize expN(x)*expN(y) as expN(x+y). */
10839 {
10845 }
10847 /* Optimizations of pow(...)*pow(...). */
10851 {
10857 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10859 {
10864 }
10866 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10868 {
10873 }
10874 }
10876 /* Optimize tan(x)*cos(x) as sin(x). */
10885 {
10891 }
10893 /* Optimize x*pow(x,c) as pow(x,c+1). */
10897 {
10903 {
10905 REAL_VALUE_TYPE c;
10906 tree arg;
10912 }
10913 }
10915 /* Optimize pow(x,c)*x as pow(x,c+1). */
10919 {
10925 {
10927 REAL_VALUE_TYPE c;
10928 tree arg;
10934 }
10935 }
10937 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10939 && optimize
10941 {
10945 {
10948 }
10949 }
10950 }
10951 }
10955 bit_ior:
10956 /* ~X | X is -1. */
10959 {
10963 }
10965 /* X | ~X is -1. */
10968 {
10972 }
10974 /* Canonicalize (X & C1) | C2. */
10978 {
10983 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10991 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10996 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10997 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10998 mode which allows further optimizations. */
11003 {
11007 {
11010 }
11011 }
11018 c3)),
11019 arg1);
11020 }
11022 /* (X & ~Y) | (~X & Y) is X ^ Y */
11025 {
11042 }
11048 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11050 This results in more efficient code for machines without a NAND
11051 instruction. Combine will canonicalize to the first form
11052 which will allow use of NAND instructions provided by the
11053 backend if they exist. */
11056 {
11057 return
11064 }
11066 /* See if this can be simplified into a rotate first. If that
11067 is unsuccessful continue in the association code. */
11071 /* ~X ^ X is -1. */
11074 {
11078 }
11080 /* X ^ ~X is -1. */
11083 {
11087 }
11089 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11090 with a constant, and the two constants have no bits in common,
11091 we should treat this as a BIT_IOR_EXPR since this may produce more
11092 simplifications. */
11099 {
11102 }
11104 /* (X | Y) ^ X -> Y & ~ X*/
11107 {
11110 arg1);
11115 }
11117 /* (Y | X) ^ X -> Y & ~ X*/
11120 {
11123 arg1);
11128 }
11130 /* X ^ (X | Y) -> Y & ~ X*/
11133 {
11136 arg0);
11141 }
11143 /* X ^ (Y | X) -> Y & ~ X*/
11146 {
11149 arg0);
11154 }
11156 /* Convert ~X ^ ~Y to X ^ Y. */
11165 /* Convert ~X ^ C to X ^ ~C. */
11173 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11181 /* Fold (X & Y) ^ Y as ~X & Y. */
11184 {
11189 }
11190 /* Fold (X & Y) ^ X as ~Y & X. */
11194 {
11199 }
11200 /* Fold X ^ (X & Y) as X & ~Y. */
11203 {
11208 }
11209 /* Fold X ^ (Y & X) as ~Y & X. */
11213 {
11218 }
11220 /* See if this can be simplified into a rotate first. If that
11221 is unsuccessful continue in the association code. */
11225 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11233 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11241 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11246 {
11247 tree tem2;
11254 }
11255 /* Fold ~X & 1 as (X & 1) == 0. */
11259 {
11260 tree tem2;
11267 }
11268 /* Fold !X & 1 as X == 0. */
11271 {
11275 }
11277 /* Fold (X ^ Y) & Y as ~X & Y. */
11280 {
11285 }
11286 /* Fold (X ^ Y) & X as ~Y & X. */
11290 {
11295 }
11296 /* Fold X & (X ^ Y) as X & ~Y. */
11299 {
11304 }
11305 /* Fold X & (Y ^ X) as ~Y & X. */
11309 {
11314 }
11316 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11317 multiple of 1 << CST. */
11319 {
11326 }
11328 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11329 bits from CST2. */
11333 {
11341 {
11342 /* Avoid the transform if arg1 is a mask of some
11343 mode which allows further optimizations. */
11350 }
11351 }
11353 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11354 ((A & N) + B) & M -> (A + B) & M
11355 Similarly if (N & M) == 0,
11356 ((A | N) + B) & M -> (A + B) & M
11357 and for - instead of + (or unary - instead of +)
11358 and/or ^ instead of |.
11359 If B is constant and (B & M) == 0, fold into A & M. */
11361 {
11370 {
11373 wide_int cst0;
11375 /* Now we know that arg0 is (C + D) or (C - D) or
11376 -C and arg1 (M) is == (1LL << cst) - 1.
11377 Store C into PMOP[0] and D into PMOP[1]. */
11381 {
11384 }
11391 {
11401 {
11404 }
11407 /* If C or D is of the form (A & N) where
11408 (N & M) == M, or of the form (A | N) or
11409 (A ^ N) where (N & M) == 0, replace it with A. */
11413 /* If C or D is a N where (N & M) == 0, it can be
11414 omitted (assumed 0). */
11422 }
11424 /* Only build anything new if we optimized one or both arguments
11425 above. */
11429 {
11432 {
11433 /* Perform the operations in a type that has defined
11434 overflow behavior. */
11440 }
11445 {
11453 else
11455 }
11458 else
11461 /* TEM is now the new binary +, - or unary - replacement. */
11465 }
11466 }
11467 }
11472 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11475 {
11480 return
11482 }
11484 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11486 This results in more efficient code for machines without a NOR
11487 instruction. Combine will canonicalize to the first form
11488 which will allow use of NOR instructions provided by the
11489 backend if they exist. */
11492 {
11499 }
11501 /* If arg0 is derived from the address of an object or function, we may
11502 be able to fold this expression using the object or function's
11503 alignment. */
11505 {
11512 /* This works because modulus is a power of 2. If this weren't the
11513 case, we'd have to replace it by its greatest power-of-2
11514 divisor: modulus & -modulus. */
11517 }
11519 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11520 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11521 if the new mask might be further optimized. */
11530 {
11541 {
11544 /* See if more bits can be proven as zero because of
11545 zero extension. */
11548 {
11553 {
11555 /* See if we can shorten the right shift. */
11558 /* Otherwise X >> C1 is all zeros, so we'll optimize
11559 it into (X, 0) later on by making sure zerobits
11560 is all ones. */
11561 }
11562 }
11565 {
11568 }
11569 /* For arithmetic shift if sign bit could be set, zerobits
11570 can contain actually sign bits, so no transformation is
11571 possible, unless MASK masks them all away. In that
11572 case the shift needs to be converted into logical shift. */
11575 {
11578 else
11580 }
11581 }
11583 /* ((X << 16) & 0xff00) is (X, 0). */
11590 {
11591 /* Only do the transformation if NEWMASK is some integer
11592 mode's mask. */
11599 {
11600 tree newmaskt;
11603 {
11609 }
11610 else
11615 }
11616 }
11617 }
11622 /* Don't touch a floating-point divide by zero unless the mode
11623 of the constant can represent infinity. */
11629 /* (-A) / (-B) -> A / B */
11639 /* Convert A/B/C to A/(B*C). */
11646 /* Convert A/(B/C) to (A/B)*C. */
11654 /* Convert C1/(X*C2) into (C1/C2)/X. */
11659 {
11665 }
11668 {
11672 /* Optimize sin(x)/cos(x) as tan(x). */
11678 {
11683 }
11685 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11691 {
11695 {
11700 }
11701 }
11703 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11704 NaNs or Infinities. */
11708 {
11715 {
11720 }
11721 }
11723 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11724 NaNs or Infinities. */
11728 {
11735 {
11739 {
11743 tmp);
11744 }
11745 }
11746 }
11748 /* Optimize pow(x,c)/x as pow(x,c-1). */
11752 {
11758 {
11760 REAL_VALUE_TYPE c;
11761 tree arg;
11767 }
11768 }
11770 /* Optimize a/root(b/c) into a*root(c/b). */
11772 {
11776 {
11785 }
11786 }
11788 /* Optimize x/expN(y) into x*expN(-y). */
11790 {
11797 }
11799 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11803 {
11811 }
11812 }
11816 /* Optimize (X & (-A)) / A where A is a power of 2,
11817 to X >> log2(A) */
11821 {
11829 }
11830 }
11832 /* Fall through */
11835 /* Simplify A / (B << N) where A and B are positive and B is
11836 a power of 2, to A >> (N + log2(B)). */
11841 {
11844 {
11852 WARN_STRICT_OVERFLOW_MISC);
11858 }
11859 }
11861 /* Fall through */
11869 /* Convert -A / -B to A / B when the type is signed and overflow is
11870 undefined. */
11874 {
11877 "when distributing negation across "
11879 WARN_STRICT_OVERFLOW_MISC);
11885 }
11889 {
11892 "when distributing negation across "
11894 WARN_STRICT_OVERFLOW_MISC);
11900 }
11902 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11903 operation, EXACT_DIV_EXPR.
11905 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11906 At one time others generated faster code, it's not clear if they do
11907 after the last round to changes to the DIV code in expmed.c. */
11916 {
11920 WARN_STRICT_OVERFLOW_MISC);
11922 }
11934 {
11938 WARN_STRICT_OVERFLOW_MISC);
11940 }
11948 /* Since negative shift count is not well-defined,
11949 don't try to compute it in the compiler. */
11955 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11960 {
11964 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11965 being well defined. */
11967 {
11973 else
11975 }
11979 }
11981 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11982 into x & ((unsigned)-1 >> c) for unsigned types. */
11990 {
11993 tree lshift;
11994 tree arg00;
11997 {
12004 }
12005 }
12007 /* If we have a rotate of a bit operation with the rotate count and
12008 the second operand of the bit operation both constant,
12009 permute the two operations. */
12021 /* Two consecutive rotates adding up to the some integer
12022 multiple of the precision of the type can be ignored. */
12030 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12031 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12032 if the latter can be further optimized. */
12037 {
12041 arg1);
12045 arg1);
12049 }
12066 /* Note that the operands of this must be ints
12067 and their values must be 0 or 1.
12068 ("true" is a fixed value perhaps depending on the language.) */
12069 /* If first arg is constant zero, return it. */
12073 /* If either arg is constant true, drop it. */
12077 /* Preserve sequence points. */
12080 /* If second arg is constant zero, result is zero, but first arg
12081 must be evaluated. */
12084 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12085 case will be handled here. */
12089 /* !X && X is always false. */
12093 /* X && !X is always false. */
12098 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12099 means A >= Y && A != MAX, but in this case we know that
12100 A < X <= MAX. */
12104 {
12112 }
12121 /* Note that the operands of this must be ints
12122 and their values must be 0 or true.
12123 ("true" is a fixed value perhaps depending on the language.) */
12124 /* If first arg is constant true, return it. */
12128 /* If either arg is constant zero, drop it. */
12132 /* Preserve sequence points. */
12135 /* If second arg is constant true, result is true, but we must
12136 evaluate first arg. */
12139 /* Likewise for first arg, but note this only occurs here for
12140 TRUTH_OR_EXPR. */
12144 /* !X || X is always true. */
12148 /* X || !X is always true. */
12153 /* (X && !Y) || (!X && Y) is X ^ Y */
12156 {
12173 }
12182 /* If the second arg is constant zero, drop it. */
12185 /* If the second arg is constant true, this is a logical inversion. */
12187 {
12190 }
12191 /* Identical arguments cancel to zero. */
12195 /* !X ^ X is always true. */
12200 /* X ^ !X is always true. */
12216 /* bool_var != 0 becomes bool_var. */
12221 /* bool_var == 1 becomes bool_var. */
12226 /* bool_var != 1 becomes !bool_var. */
12233 /* bool_var == 0 becomes !bool_var. */
12240 /* !exp != 0 becomes !exp */
12245 /* If this is an equality comparison of the address of two non-weak,
12246 unaliased symbols neither of which are extern (since we do not
12247 have access to attributes for externs), then we know the result. */
12252 {
12260 else
12265 type);
12266 }
12268 /* Similarly for a NEGATE_EXPR. */
12272 arg1)))
12277 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12285 arg1),
12288 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12297 {
12301 val,
12305 }
12307 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12314 {
12316 code == NE_EXPR
12319 }
12321 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12326 /* If this is an EQ or NE comparison with zero and ARG0 is
12327 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12328 two operations, but the latter can be done in one less insn
12329 on machines that have only two-operand insns or on which a
12330 constant cannot be the first operand. */
12333 {
12338 {
12345 arg1);
12346 }
12349 {
12356 arg1);
12357 }
12358 }
12360 /* If this is an NE or EQ comparison of zero against the result of a
12361 signed MOD operation whose second operand is a power of 2, make
12362 the MOD operation unsigned since it is simpler and equivalent. */
12370 {
12380 }
12382 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12383 C1 is a valid shift constant, and C2 is a power of two, i.e.
12384 a single bit. */
12388 == INTEGER_CST
12391 {
12396 /* Check for a valid shift count. */
12398 {
12402 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12403 can be rewritten as (X & (C2 << C1)) != 0. */
12405 {
12410 }
12411 /* Otherwise, for signed (arithmetic) shifts,
12412 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12413 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12417 /* Otherwise, of unsigned (logical) shifts,
12418 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12419 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12420 else
12424 arg000);
12425 }
12426 }
12428 /* If we have (A & C) == C where C is a power of 2, convert this into
12429 (A & C) != 0. Similarly for NE_EXPR. */
12435 integer_zero_node));
12437 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12438 bit, then fold the expression into A < 0 or A >= 0. */
12443 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12444 Similarly for NE_EXPR. */
12448 {
12452 tree dandnotc
12455 notc);
12459 }
12461 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12462 Similarly for NE_EXPR. */
12466 {
12468 tree candnotd
12475 }
12477 /* If this is a comparison of a field, we may be able to simplify it. */
12480 /* Handle the constant case even without -O
12481 to make sure the warnings are given. */
12483 {
12487 }
12489 /* Optimize comparisons of strlen vs zero to a compare of the
12490 first character of the string vs zero. To wit,
12491 strlen(ptr) == 0 => *ptr == 0
12492 strlen(ptr) != 0 => *ptr != 0
12493 Other cases should reduce to one of these two (or a constant)
12494 due to the return value of strlen being unsigned. */
12497 {
12505 {
12510 }
12511 }
12513 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12514 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12518 {
12523 {
12525 {
12528 }
12531 }
12532 }
12534 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12540 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12545 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12552 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12560 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12561 (X & C) == 0 when C is a single bit. */
12566 {
12573 arg1));
12574 }
12576 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12577 constant C is a power of two, i.e. a single bit. */
12584 {
12588 }
12590 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12591 when is C is a power of two, i.e. a single bit. */
12598 {
12604 }
12608 {
12611 }
12613 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12621 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12624 {
12637 arg01),
12646 arg01),
12655 arg00),
12664 arg00),
12666 }
12670 {
12677 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12678 operand_equal_p guarantees no side-effects so we don't need
12679 to use omit_one_operand on Z. */
12683 arg10));
12687 arg11));
12691 arg10));
12695 arg11));
12697 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12700 {
12706 }
12707 }
12709 /* Attempt to simplify equality/inequality comparisons of complex
12710 values. Only lower the comparison if the result is known or
12711 can be simplified to a single scalar comparison. */
12716 {
12721 {
12724 }
12725 else
12726 {
12729 }
12732 {
12735 }
12736 else
12737 {
12740 }
12744 {
12746 {
12751 }
12752 else
12753 {
12758 }
12759 }
12763 {
12765 {
12770 }
12771 else
12772 {
12777 }
12778 }
12779 }
12791 /* Transform comparisons of the form X +- C CMP X. */
12798 {
12805 else
12808 /* (X - c) > X becomes false. */
12812 {
12816 "occur when assuming that (X - c) > X "
12818 WARN_STRICT_OVERFLOW_ALL);
12820 }
12822 /* Likewise (X + c) < X becomes false. */
12826 {
12830 "occur when assuming that "
12832 WARN_STRICT_OVERFLOW_ALL);
12834 }
12836 /* Convert (X - c) <= X to true. */
12841 {
12845 "occur when assuming that "
12847 WARN_STRICT_OVERFLOW_ALL);
12849 }
12851 /* Convert (X + c) >= X to true. */
12856 {
12860 "occur when assuming that "
12862 WARN_STRICT_OVERFLOW_ALL);
12864 }
12867 {
12868 /* Convert X + c > X and X - c < X to true for integers. */
12872 {
12875 "not occur when assuming that "
12877 WARN_STRICT_OVERFLOW_ALL);
12879 }
12884 {
12887 "not occur when assuming that "
12889 WARN_STRICT_OVERFLOW_ALL);
12891 }
12893 /* Convert X + c <= X and X - c >= X to false for integers. */
12897 {
12900 "not occur when assuming that "
12902 WARN_STRICT_OVERFLOW_ALL);
12904 }
12909 {
12912 "not occur when assuming that "
12914 WARN_STRICT_OVERFLOW_ALL);
12916 }
12917 }
12918 }
12920 /* Comparisons with the highest or lowest possible integer of
12921 the specified precision will have known values. */
12922 {
12928 {
12935 {
12948 /* The GE_EXPR and LT_EXPR cases above are not normally
12949 reached because of previous transformations. */
12953 }
12956 {
12963 arg1);
12969 arg0),
12970 arg1);
12973 }
12976 {
12991 }
12994 {
13001 arg1);
13007 arg0),
13008 arg1);
13011 }
13015 /* We will flip the signedness of the comparison operator
13016 associated with the mode of arg1, so the sign bit is
13017 specified by this mode. Check that arg1 is the signed
13018 max associated with this sign bit. */
13020 /* signed_type does not work on pointer types. */
13022 {
13023 /* The following case also applies to X < signed_max+1
13024 and X >= signed_max+1 because previous transformations. */
13026 {
13032 }
13033 }
13034 }
13035 }
13037 /* If we are comparing an ABS_EXPR with a constant, we can
13038 convert all the cases into explicit comparisons, but they may
13039 well not be faster than doing the ABS and one comparison.
13040 But ABS (X) <= C is a range comparison, which becomes a subtraction
13041 and a comparison, and is probably faster. */
13055 /* Convert ABS_EXPR<x> >= 0 to true. */
13062 {
13065 "when simplifying comparison of "
13067 WARN_STRICT_OVERFLOW_CONDITIONAL);
13070 arg0);
13071 }
13073 /* Convert ABS_EXPR<x> < 0 to false. */
13078 {
13081 "when simplifying comparison of "
13083 WARN_STRICT_OVERFLOW_CONDITIONAL);
13086 arg0);
13087 }
13089 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13090 and similarly for >= into !=. */
13100 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13101 otherwise Y might be >= # of bits in X's type and thus e.g.
13102 (unsigned char) (1 << Y) for Y 15 might be 0.
13103 If the cast is widening, then 1 << Y should have unsigned type,
13104 otherwise if Y is number of bits in the signed shift type minus 1,
13105 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13106 31 might be 0xffffffff80000000. */
13117 {
13123 }
13136 {
13140 }
13142 /* If the first operand is NaN, the result is constant. */
13146 {
13148 ? integer_zero_node
13151 }
13153 /* If the second operand is NaN, the result is constant. */
13157 {
13159 ? integer_zero_node
13162 }
13164 /* Simplify unordered comparison of something with itself. */
13170 && !flag_trapping_math
13174 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13175 {
13187 }
13192 /* When pedantic, a compound expression can be neither an lvalue
13193 nor an integer constant expression. */
13196 /* Don't let (0, 0) be null pointer constant. */
13202 /* An ASSERT_EXPR should never be passed to fold_binary. */
13208 }
13210 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13211 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13212 of GOTO_EXPR. */
13214 static tree
13216 {
13218 {
13225 /* ... fall through ... */
13229 }
13230 }
13232 /* Return whether the sub-tree ST contains a label which is accessible from
13233 outside the sub-tree. */
13235 static bool
13237 {
13238 return
13240 }
13242 /* Fold a ternary expression of code CODE and type TYPE with operands
13243 OP0, OP1, and OP2. Return the folded expression if folding is
13244 successful. Otherwise, return NULL_TREE. */
13246 tree
13249 {
13250 tree tem;
13257 /* If this is a commutative operation, and OP0 is a constant, move it
13258 to OP1 to reduce the number of tests below. */
13267 /* Strip any conversions that don't change the mode. This is safe
13268 for every expression, except for a comparison expression because
13269 its signedness is derived from its operands. So, in the latter
13270 case, only strip conversions that don't change the signedness.
13272 Note that this is done as an internal manipulation within the
13273 constant folder, in order to find the simplest representation of
13274 the arguments so that their form can be studied. In any cases,
13275 the appropriate type conversions should be put back in the tree
13276 that will get out of the constant folder. */
13278 {
13281 }
13284 {
13287 }
13290 {
13293 }
13296 {
13300 {
13306 }
13311 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13312 so all simple results must be passed through pedantic_non_lvalue. */
13314 {
13317 /* Only optimize constant conditions when the selected branch
13318 has the same type as the COND_EXPR. This avoids optimizing
13319 away "c ? x : throw", where the throw has a void type.
13320 Avoid throwing away that operand which contains label. */
13327 }
13329 {
13334 {
13339 {
13347 }
13351 }
13352 }
13354 /* If we have A op B ? A : C, we may be able to convert this to a
13355 simpler expression, depending on the operation and the values
13356 of B and C. Signed zeros prevent all of these transformations,
13357 for reasons given above each one.
13359 Also try swapping the arguments and inverting the conditional. */
13364 {
13368 }
13372 op2,
13375 {
13379 {
13383 }
13384 }
13386 /* If the second operand is simpler than the third, swap them
13387 since that produces better jump optimization results. */
13390 {
13392 /* See if this can be inverted. If it can't, possibly because
13393 it was a floating-point inequality comparison, don't do
13394 anything. */
13398 }
13400 /* Convert A ? 1 : 0 to simply A. */
13405 /* If we try to convert OP0 to our type, the
13406 call to fold will try to move the conversion inside
13407 a COND, which will recurse. In that case, the COND_EXPR
13408 is probably the best choice, so leave it alone. */
13412 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13413 over COND_EXPR in cases such as floating point comparisons. */
13422 arg0)));
13424 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13429 {
13430 /* sign_bit_p looks through both zero and sign extensions,
13431 but for this optimization only sign extensions are
13432 usable. */
13435 {
13438 {
13441 }
13443 }
13444 /* sign_bit_p only checks ARG1 bits within A's precision.
13445 If <sign bit of A> has wider type than A, bits outside
13446 of A's precision in <sign bit of A> need to be checked.
13447 If they are all 0, this optimization needs to be done
13448 in unsigned A's type, if they are all 1 in signed A's type,
13449 otherwise this can't be done. */
13455 {
13457 tree tem_type;
13470 {
13473 }
13475 {
13478 }
13479 else
13481 }
13484 return
13490 arg1)));
13491 }
13493 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13494 already handled above. */
13499 {
13508 }
13510 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13511 is probably obsolete because the first operand should be a
13512 truth value (that's why we have the two cases above), but let's
13513 leave it in until we can confirm this for all front-ends. */
13525 /* Disable the transformations below for vectors, since
13526 fold_binary_op_with_conditional_arg may undo them immediately,
13527 yielding an infinite loop. */
13531 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13540 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13545 {
13547 /* Only perform transformation if ARG0 is easily inverted. */
13551 ? BIT_IOR_EXPR
13554 arg1);
13555 }
13557 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13562 {
13564 /* Only perform transformation if ARG0 is easily inverted. */
13570 op2);
13571 }
13573 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13585 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13586 of fold_ternary on them. */
13596 {
13606 {
13611 {
13619 }
13621 /* Constructor elements can be subvectors. */
13624 {
13628 }
13630 /* We keep an exact subset of the constructor elements. */
13632 {
13638 {
13642 }
13650 CONSTRUCTOR_ELT
13653 }
13654 /* The bitfield references a single constructor element. */
13656 {
13661 else
13665 }
13666 }
13667 }
13669 /* A bit-field-ref that referenced the full argument can be stripped. */
13675 /* On constants we can use native encode/interpret to constant
13676 fold (nearly) all BIT_FIELD_REFs. */
13680 /* This limitation should not be necessary, we just need to
13681 round this up to mode size. */
13683 /* Need bit-shifting of the buffer to relax the following. */
13685 {
13690 /* ??? We cannot tell native_encode_expr to start at
13691 some random byte only. So limit us to a reasonable amount
13692 of work. */
13694 {
13699 {
13705 }
13706 }
13707 }
13712 /* For integers we can decompose the FMA if possible. */
13724 {
13740 {
13745 /* Make sure that the perm value is in an acceptable
13746 range. */
13755 else
13760 }
13763 {
13768 }
13773 {
13778 }
13784 {
13788 }
13793 /* Some targets are deficient and fail to expand a single
13794 argument permutation while still allowing an equivalent
13795 2-argument version. */
13799 {
13802 }
13805 {
13812 }
13816 }
13822 }
13824 /* Perform constant folding and related simplification of EXPR.
13825 The related simplifications include x*1 => x, x*0 => 0, etc.,
13826 and application of the associative law.
13827 NOP_EXPR conversions may be removed freely (as long as we
13828 are careful not to change the type of the overall expression).
13829 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13830 but we can constant-fold them if they have constant operands. */
13832 #ifdef ENABLE_FOLD_CHECKING
13833 # define fold(x) fold_1 (x)
13835 static
13836 #endif
13837 tree
13839 {
13843 tree tem;
13846 /* Return right away if a constant. */
13850 /* CALL_EXPR-like objects with variable numbers of operands are
13851 treated specially. */
13853 {
13855 {
13858 }
13860 }
13863 {
13868 {
13886 }
13887 }
13890 {
13892 {
13899 {
13904 /* Find a matching index by means of a binary search. */
13906 {
13922 else
13924 }
13925 }
13928 }
13930 /* Return a VECTOR_CST if possible. */
13932 {
13939 tree value;
13942 {
13946 {
13949 }
13950 else
13952 }
13957 }
13965 }
13967 #ifdef ENABLE_FOLD_CHECKING
13968 #undef fold
13975 /* When --enable-checking=fold, compute a digest of expr before
13976 and after actual fold call to see if fold did not accidentally
13977 change original expr. */
13979 tree
13981 {
13982 tree ret;
14002 }
14004 void
14006 {
14017 }
14019 static void
14021 {
14023 }
14025 static void
14028 {
14034 recursive_label:
14044 {
14045 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
14050 }
14057 {
14058 /* Allow these fields to be modified. */
14059 tree tmp;
14067 {
14070 }
14071 }
14082 {
14085 {
14100 }
14104 {
14117 }
14134 {
14140 }
14143 {
14145 {
14148 }
14150 }
14161 {
14164 }
14174 }
14175 }
14177 /* Helper function for outputting the checksum of a tree T. When
14178 debugging with gdb, you can "define mynext" to be "next" followed
14179 by "call debug_fold_checksum (op0)", then just trace down till the
14180 outputs differ. */
14182 DEBUG_FUNCTION void
14184 {
14199 }
14201 #endif
14203 /* Fold a unary tree expression with code CODE of type TYPE with an
14204 operand OP0. LOC is the location of the resulting expression.
14205 Return a folded expression if successful. Otherwise, return a tree
14206 expression with code CODE of type TYPE with an operand OP0. */
14208 tree
14211 {
14212 tree tem;
14213 #ifdef ENABLE_FOLD_CHECKING
14222 #endif
14228 #ifdef ENABLE_FOLD_CHECKING
14235 #endif
14237 }
14239 /* Fold a binary tree expression with code CODE of type TYPE with
14240 operands OP0 and OP1. LOC is the location of the resulting
14241 expression. Return a folded expression if successful. Otherwise,
14242 return a tree expression with code CODE of type TYPE with operands
14243 OP0 and OP1. */
14245 tree
14248 MEM_STAT_DECL)
14249 {
14250 tree tem;
14251 #ifdef ENABLE_FOLD_CHECKING
14268 #endif
14274 #ifdef ENABLE_FOLD_CHECKING
14289 #endif
14291 }
14293 /* Fold a ternary tree expression with code CODE of type TYPE with
14294 operands OP0, OP1, and OP2. Return a folded expression if
14295 successful. Otherwise, return a tree expression with code CODE of
14296 type TYPE with operands OP0, OP1, and OP2. */
14298 tree
14301 {
14302 tree tem;
14303 #ifdef ENABLE_FOLD_CHECKING
14327 #endif
14334 #ifdef ENABLE_FOLD_CHECKING
14357 #endif
14359 }
14361 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14362 arguments in ARGARRAY, and a null static chain.
14363 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14364 of type TYPE from the given operands as constructed by build_call_array. */
14366 tree
14369 {
14370 tree tem;
14371 #ifdef ENABLE_FOLD_CHECKING
14390 #endif
14396 #ifdef ENABLE_FOLD_CHECKING
14412 #endif
14414 }
14416 /* Perform constant folding and related simplification of initializer
14417 expression EXPR. These behave identically to "fold_buildN" but ignore
14418 potential run-time traps and exceptions that fold must preserve. */
14420 #define START_FOLD_INIT \
14421 int saved_signaling_nans = flag_signaling_nans;\
14422 int saved_trapping_math = flag_trapping_math;\
14423 int saved_rounding_math = flag_rounding_math;\
14424 int saved_trapv = flag_trapv;\
14425 int saved_folding_initializer = folding_initializer;\
14426 flag_signaling_nans = 0;\
14427 flag_trapping_math = 0;\
14428 flag_rounding_math = 0;\
14429 flag_trapv = 0;\
14430 folding_initializer = 1;
14432 #define END_FOLD_INIT \
14433 flag_signaling_nans = saved_signaling_nans;\
14434 flag_trapping_math = saved_trapping_math;\
14435 flag_rounding_math = saved_rounding_math;\
14436 flag_trapv = saved_trapv;\
14437 folding_initializer = saved_folding_initializer;
14439 tree
14442 {
14443 tree result;
14444 START_FOLD_INIT;
14448 END_FOLD_INIT;
14450 }
14452 tree
14455 {
14456 tree result;
14457 START_FOLD_INIT;
14461 END_FOLD_INIT;
14463 }
14465 tree
14468 {
14469 tree result;
14470 START_FOLD_INIT;
14474 END_FOLD_INIT;
14476 }
14478 #undef START_FOLD_INIT
14479 #undef END_FOLD_INIT
14481 /* Determine if first argument is a multiple of second argument. Return 0 if
14482 it is not, or we cannot easily determined it to be.
14484 An example of the sort of thing we care about (at this point; this routine
14485 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14486 fold cases do now) is discovering that
14488 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14490 is a multiple of
14492 SAVE_EXPR (J * 8)
14494 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14496 This code also handles discovering that
14498 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14500 is a multiple of 8 so we don't have to worry about dealing with a
14501 possible remainder.
14503 Note that we *look* inside a SAVE_EXPR only to determine how it was
14504 calculated; it is not safe for fold to do much of anything else with the
14505 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14506 at run time. For example, the latter example above *cannot* be implemented
14507 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14508 evaluation time of the original SAVE_EXPR is not necessarily the same at
14509 the time the new expression is evaluated. The only optimization of this
14510 sort that would be valid is changing
14512 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14514 divided by 8 to
14516 SAVE_EXPR (I) * SAVE_EXPR (J)
14518 (where the same SAVE_EXPR (J) is used in the original and the
14519 transformed version). */
14521 int
14523 {
14531 {
14533 /* Bitwise and provides a power of two multiple. If the mask is
14534 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14537 /* FALLTHRU */
14550 {
14554 /* const_binop may not detect overflow correctly,
14555 so check for it explicitly here. */
14559 size_one_node,
14560 op1)))
14563 }
14567 /* Can't handle conversions from non-integral or wider integral type. */
14573 /* .. fall through ... */
14590 SIGNED);
14594 }
14595 }
14597 /* Return true if CODE or TYPE is known to be non-negative. */
14599 static bool
14601 {
14604 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14605 have a signed:1 type (where the value is -1 and 0). */
14608 }
14610 /* Return true if (CODE OP0) is known to be non-negative. If the return
14611 value is based on the assumption that signed overflow is undefined,
14612 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14613 *STRICT_OVERFLOW_P. */
14615 bool
14618 {
14623 {
14625 /* We can't return 1 if flag_wrapv is set because
14626 ABS_EXPR<INT_MIN> = INT_MIN. */
14630 {
14633 }
14640 strict_overflow_p);
14642 CASE_CONVERT:
14643 {
14648 {
14651 strict_overflow_p);
14653 {
14657 strict_overflow_p);
14658 }
14659 }
14661 {
14664 strict_overflow_p);
14668 }
14669 }
14674 }
14676 /* We don't know sign of `t', so be conservative and return false. */
14678 }
14680 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14681 value is based on the assumption that signed overflow is undefined,
14682 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14683 *STRICT_OVERFLOW_P. */
14685 bool
14688 {
14693 {
14698 strict_overflow_p)
14700 strict_overflow_p));
14702 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14703 both unsigned and at least 2 bits shorter than the result. */
14707 {
14712 {
14716 }
14717 }
14722 {
14723 /* x * x is always non-negative for floating point x
14724 or without overflow. */
14728 {
14733 }
14734 }
14736 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14737 both unsigned and their total bits is shorter than the result. */
14741 {
14760 {
14770 }
14771 }
14777 strict_overflow_p)
14779 strict_overflow_p));
14790 strict_overflow_p)
14792 strict_overflow_p));
14799 strict_overflow_p);
14802 }
14804 /* We don't know sign of `t', so be conservative and return false. */
14806 }
14808 /* Return true if T is known to be non-negative. If the return
14809 value is based on the assumption that signed overflow is undefined,
14810 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14811 *STRICT_OVERFLOW_P. */
14813 bool
14815 {
14820 {
14832 strict_overflow_p)
14834 strict_overflow_p));
14838 }
14839 /* We don't know sign of `t', so be conservative and return false. */
14841 }
14843 /* Return true if T is known to be non-negative. If the return
14844 value is based on the assumption that signed overflow is undefined,
14845 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14846 *STRICT_OVERFLOW_P. */
14848 bool
14851 {
14854 {
14874 /* Always true. */
14878 /* sqrt(-0.0) is -0.0. */
14882 strict_overflow_p);
14919 /* True if the 1st argument is nonnegative. */
14921 strict_overflow_p);
14924 /* True if the 1st OR 2nd arguments are nonnegative. */
14926 strict_overflow_p)
14928 strict_overflow_p)));
14931 /* True if the 1st AND 2nd arguments are nonnegative. */
14933 strict_overflow_p)
14935 strict_overflow_p)));
14938 /* True if the 2nd argument is nonnegative. */
14940 strict_overflow_p);
14943 /* True if the 1st argument is nonnegative or the second
14944 argument is an even integer. */
14949 strict_overflow_p);
14952 /* True if the 1st argument is nonnegative or the second
14953 argument is an even integer valued real. */
14955 {
14956 REAL_VALUE_TYPE c;
14957 HOST_WIDE_INT n;
14962 {
14963 REAL_VALUE_TYPE cint;
14967 }
14968 }
14970 strict_overflow_p);
14974 }
14976 type);
14977 }
14979 /* Return true if T is known to be non-negative. If the return
14980 value is based on the assumption that signed overflow is undefined,
14981 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14982 *STRICT_OVERFLOW_P. */
14984 static bool
14986 {
14992 {
14994 {
14998 /* If the initializer is non-void, then it's a normal expression
14999 that will be assigned to the slot. */
15003 /* Otherwise, the initializer sets the slot in some way. One common
15004 way is an assignment statement at the end of the initializer. */
15006 {
15014 else
15016 }
15020 strict_overflow_p);
15023 }
15026 {
15032 arg0,
15033 arg1,
15034 strict_overflow_p);
15035 }
15039 strict_overflow_p);
15042 strict_overflow_p);
15045 strict_overflow_p);
15050 }
15052 /* We don't know sign of `t', so be conservative and return false. */
15054 }
15056 /* Return true if T is known to be non-negative. If the return
15057 value is based on the assumption that signed overflow is undefined,
15058 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15059 *STRICT_OVERFLOW_P. */
15061 bool
15063 {
15070 {
15077 strict_overflow_p);
15083 strict_overflow_p);
15092 }
15095 {
15103 strict_overflow_p);
15108 strict_overflow_p);
15121 }
15122 }
15124 /* Return true if `t' is known to be non-negative. Handle warnings
15125 about undefined signed overflow. */
15127 bool
15129 {
15136 "determining that expression is always "
15138 WARN_STRICT_OVERFLOW_MISC);
15140 }
15143 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15144 For floating point we further ensure that T is not denormal.
15145 Similar logic is present in nonzero_address in rtlanal.h.
15147 If the return value is based on the assumption that signed overflow
15148 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15149 change *STRICT_OVERFLOW_P. */
15151 bool
15154 {
15156 {
15159 strict_overflow_p);
15162 {
15168 strict_overflow_p));
15169 }
15174 strict_overflow_p);
15178 }
15181 }
15183 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15184 For floating point we further ensure that T is not denormal.
15185 Similar logic is present in nonzero_address in rtlanal.h.
15187 If the return value is based on the assumption that signed overflow
15188 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15189 change *STRICT_OVERFLOW_P. */
15191 bool
15193 tree type,
15194 tree op0,
15196 {
15199 {
15203 {
15204 /* With the presence of negative values it is hard
15205 to say something. */
15212 /* One of operands must be positive and the other non-negative. */
15213 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15214 overflows, on a twos-complement machine the sum of two
15215 nonnegative numbers can never be zero. */
15217 strict_overflow_p)
15219 strict_overflow_p));
15220 }
15225 {
15227 strict_overflow_p)
15229 strict_overflow_p))
15230 {
15233 }
15234 }
15243 {
15246 }
15253 {
15257 /* When both operands are nonzero, then MAX must be too. */
15259 strict_overflow_p))
15262 /* MAX where operand 0 is positive is positive. */
15264 strict_overflow_p);
15265 }
15266 /* MAX where operand 1 is positive is positive. */
15271 {
15275 }
15280 strict_overflow_p)
15282 strict_overflow_p));
15286 }
15289 }
15291 /* Return true when T is an address and is known to be nonzero.
15292 For floating point we further ensure that T is not denormal.
15293 Similar logic is present in nonzero_address in rtlanal.h.
15295 If the return value is based on the assumption that signed overflow
15296 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15297 change *STRICT_OVERFLOW_P. */
15299 bool
15301 {
15304 {
15309 {
15318 /* For objects in symbol table check if we know they are non-zero.
15319 Don't do anything for variables and functions before symtab is built;
15320 it is quite possible that they will be declared weak later. */
15322 {
15328 else
15330 }
15332 /* Function local objects are never NULL. */
15339 /* Constants are never weak. */
15344 }
15352 {
15356 }
15361 }
15363 }
15365 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15366 attempt to fold the expression to a constant without modifying TYPE,
15367 OP0 or OP1.
15369 If the expression could be simplified to a constant, then return
15370 the constant. If the expression would not be simplified to a
15371 constant, then return NULL_TREE. */
15373 tree
15375 {
15378 }
15380 /* Given the components of a unary expression CODE, TYPE and OP0,
15381 attempt to fold the expression to a constant without modifying
15382 TYPE or OP0.
15384 If the expression could be simplified to a constant, then return
15385 the constant. If the expression would not be simplified to a
15386 constant, then return NULL_TREE. */
15388 tree
15390 {
15393 }
15395 /* If EXP represents referencing an element in a constant string
15396 (either via pointer arithmetic or array indexing), return the
15397 tree representing the value accessed, otherwise return NULL. */
15399 tree
15401 {
15405 {
15407 tree index;
15408 tree string;
15413 else
15414 {
15418 /* Optimize the special-case of a zero lower bound.
15420 We convert the low_bound to sizetype to avoid some problems
15421 with constant folding. (E.g. suppose the lower bound is 1,
15422 and its mode is QI. Without the conversion,l (ARRAY
15423 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15424 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15430 }
15443 }
15445 }
15447 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15448 an integer constant, real, or fixed-point constant.
15450 TYPE is the type of the result. */
15452 static tree
15454 {
15458 {
15460 {
15467 }
15474 {
15475 FIXED_VALUE_TYPE f;
15480 /* Propagate overflow flags. */
15484 }
15488 }
15491 }
15493 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15494 an integer constant or real constant.
15496 TYPE is the type of the result. */
15498 tree
15500 {
15504 {
15506 {
15507 /* If the value is unsigned or non-negative, then the absolute value
15508 is the same as the ordinary value. */
15512 /* If the value is negative, then the absolute value is
15513 its negation. */
15514 else
15515 {
15520 }
15521 }
15527 else
15533 }
15536 }
15538 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15539 constant. TYPE is the type of the result. */
15541 static tree
15543 {
15547 }
15549 /* Given CODE, a relational operator, the target type, TYPE and two
15550 constant operands OP0 and OP1, return the result of the
15551 relational operation. If the result is not a compile time
15552 constant, then return NULL_TREE. */
15554 static tree
15556 {
15559 /* From here on, the only cases we handle are when the result is
15560 known to be a constant. */
15563 {
15567 /* Handle the cases where either operand is a NaN. */
15569 {
15571 {
15599 }
15602 }
15605 }
15608 {
15612 }
15614 /* Handle equality/inequality of complex constants. */
15616 {
15627 else
15629 }
15632 {
15639 {
15651 }
15654 }
15656 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15658 To compute GT, swap the arguments and do LT.
15659 To compute GE, do LT and invert the result.
15660 To compute LE, swap the arguments, do LT and invert the result.
15661 To compute NE, do EQ and invert the result.
15663 Therefore, the code below must handle only EQ and LT. */
15666 {
15669 }
15671 /* Note that it is safe to invert for real values here because we
15672 have already handled the one case that it matters. */
15676 {
15679 }
15681 /* Compute a result for LT or EQ if args permit;
15682 Otherwise return T. */
15684 {
15687 else
15689 }
15690 else
15696 }
15698 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15699 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15700 itself. */
15702 tree
15704 {
15705 /* If the expression does not have side effects then we don't have to wrap
15706 it with a cleanup point expression. */
15710 /* If the expression is a return, check to see if the expression inside the
15711 return has no side effects or the right hand side of the modify expression
15712 inside the return. If either don't have side effects set we don't need to
15713 wrap the expression in a cleanup point expression. Note we don't check the
15714 left hand side of the modify because it should always be a return decl. */
15716 {
15723 }
15726 }
15728 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15729 of an indirection through OP0, or NULL_TREE if no simplification is
15730 possible. */
15732 tree
15734 {
15736 tree subtype;
15744 {
15747 /* *&CONST_DECL -> to the value of the const decl. */
15750 /* *&p => p; make sure to handle *&"str"[cst] here. */
15752 {
15756 else
15758 }
15759 /* *(foo *)&fooarray => fooarray[0] */
15762 && (!in_gimple_form
15764 {
15774 }
15775 /* *(foo *)&complexfoo => __real__ complexfoo */
15779 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15782 {
15786 }
15787 }
15791 {
15797 {
15798 tree op00type;
15802 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15805 {
15817 }
15818 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15821 {
15825 }
15826 /* ((foo *)&fooarray)[1] => fooarray[1] */
15829 {
15839 }
15840 }
15841 }
15843 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15846 && (!in_gimple_form
15848 {
15849 tree type_domain;
15859 NULL_TREE);
15860 }
15863 }
15865 /* Builds an expression for an indirection through T, simplifying some
15866 cases. */
15868 tree
15870 {
15878 }
15880 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15882 tree
15884 {
15889 else
15891 }
15893 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15894 whose result is ignored. The type of the returned tree need not be
15895 the same as the original expression. */
15897 tree
15899 {
15905 {
15916 else
15922 {
15938 }
15943 }
15944 }
15946 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15948 tree
15950 {
15956 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15957 have to do anything. Only do this when we are not given a const,
15958 because in that case, this check is more expensive than just
15959 doing it. */
15961 {
15966 }
15968 /* If divisor is a power of two, simplify this to bit manipulation. */
15970 {
15972 {
15986 }
15987 else
15988 {
15989 tree t;
15995 }
15996 }
15997 else
15998 {
16003 }
16006 }
16008 /* Likewise, but round down. */
16010 tree
16012 {
16019 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16020 have to do anything. Only do this when we are not given a const,
16021 because in that case, this check is more expensive than just
16022 doing it. */
16024 {
16029 }
16031 /* If divisor is a power of two, simplify this to bit manipulation. */
16033 {
16034 tree t;
16038 }
16039 else
16040 {
16045 }
16048 }
16050 /* Returns the pointer to the base of the object addressed by EXP and
16051 extracts the information about the offset of the access, storing it
16052 to PBITPOS and POFFSET. */
16054 static tree
16057 {
16058 tree core;
16059 machine_mode mode;
16061 HOST_WIDE_INT bitsize;
16065 {
16070 }
16071 else
16072 {
16076 }
16079 }
16081 /* Returns true if addresses of E1 and E2 differ by a constant, false
16082 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16084 bool
16086 {
16100 {
16110 }
16112 {
16113 /* If only one of the offsets is non-constant, the difference cannot
16114 be a constant. */
16116 }
16117 else
16122 }
16124 /* Simplify the floating point expression EXP when the sign of the
16125 result is not significant. Return NULL_TREE if no simplification
16126 is possible. */
16128 tree
16130 {
16135 {
16171 {
16174 {
16176 /* Strip copysign function call, return the 1st argument. */
16182 /* Strip sign ops from the argument of "odd" math functions. */
16184 {
16188 }
16190 }
16191 }
16196 }
16198 }
16200 /* Return OFF converted to a pointer offset type suitable as offset for
16201 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16202 tree
16204 {
16206 }
16208 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16209 tree
16211 {
16214 }
16216 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16217 tree
16219 {
16222 }