| blob | 94d1cbfc2b238f53ddbb9035646c0e19d1dacaa1 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2014 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
129 HOST_WIDE_INT *,
162 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
163 Otherwise, return LOC. */
165 static location_t
167 {
170 }
172 /* Similar to protected_set_expr_location, but never modify x in place,
173 if location can and needs to be set, unshare it. */
177 {
183 {
186 }
188 }
189 \f
190 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
191 division and returns the quotient. Otherwise returns
192 NULL_TREE. */
194 tree
196 {
197 widest_int quo;
204 }
205 \f
206 /* This is nonzero if we should defer warnings about undefined
207 overflow. This facility exists because these warnings are a
208 special case. The code to estimate loop iterations does not want
209 to issue any warnings, since it works with expressions which do not
210 occur in user code. Various bits of cleanup code call fold(), but
211 only use the result if it has certain characteristics (e.g., is a
212 constant); that code only wants to issue a warning if the result is
213 used. */
217 /* If a warning about undefined overflow is deferred, this is the
218 warning. Note that this may cause us to turn two warnings into
219 one, but that is fine since it is sufficient to only give one
220 warning per expression. */
224 /* If a warning about undefined overflow is deferred, this is the
225 level at which the warning should be emitted. */
229 /* Start deferring overflow warnings. We could use a stack here to
230 permit nested calls, but at present it is not necessary. */
232 void
234 {
236 }
238 /* Stop deferring overflow warnings. If there is a pending warning,
239 and ISSUE is true, then issue the warning if appropriate. STMT is
240 the statement with which the warning should be associated (used for
241 location information); STMT may be NULL. CODE is the level of the
242 warning--a warn_strict_overflow_code value. This function will use
243 the smaller of CODE and the deferred code when deciding whether to
244 issue the warning. CODE may be zero to mean to always use the
245 deferred code. */
247 void
249 {
251 location_t locus;
256 {
262 }
273 /* Use the smallest code level when deciding to issue the
274 warning. */
283 else
286 }
288 /* Stop deferring overflow warnings, ignoring any deferred
289 warnings. */
291 void
293 {
295 }
297 /* Whether we are deferring overflow warnings. */
299 bool
301 {
303 }
305 /* This is called when we fold something based on the fact that signed
306 overflow is undefined. */
308 static void
310 {
312 {
315 {
318 }
319 }
322 }
323 \f
324 /* Return true if the built-in mathematical function specified by CODE
325 is odd, i.e. -f(x) == f(-x). */
327 static bool
329 {
331 {
365 }
367 }
369 /* Check whether we may negate an integer constant T without causing
370 overflow. */
372 bool
374 {
375 tree type;
384 }
386 /* Determine whether an expression T can be cheaply negated using
387 the function negate_expr without introducing undefined overflow. */
389 static bool
391 {
392 tree type;
401 {
406 /* Check that -CST will not overflow type. */
419 /* We want to canonicalize to positive real constants. Pretend
420 that only negative ones can be easily negated. */
428 {
439 }
452 /* -(A + B) -> (-B) - A. */
457 /* -(A + B) -> (-A) - B. */
461 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
471 /* Fall through. */
482 /* In general we can't negate A / B, because if A is INT_MIN and
483 B is 1, we may turn this into INT_MIN / -1 which is undefined
484 and actually traps on some architectures. But if overflow is
485 undefined, we can negate, because - (INT_MIN / 1) is an
486 overflow. */
488 {
491 /* If overflow is undefined then we have to be careful because
492 we ask whether it's ok to associate the negate with the
493 division which is not ok for example for
494 -((a - b) / c) where (-(a - b)) / c may invoke undefined
495 overflow because of negating INT_MIN. So do not use
496 negate_expr_p here but open-code the two important cases. */
501 }
507 /* Negate -((double)float) as (double)(-float). */
509 {
513 }
517 /* Negate -f(x) as f(-x). */
523 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
525 {
529 }
534 }
536 }
538 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
539 simplification is possible.
540 If negate_expr_p would return true for T, NULL_TREE will never be
541 returned. */
543 static tree
545 {
547 tree tem;
550 {
551 /* Convert - (~A) to A + 1. */
576 {
581 }
585 {
590 {
594 }
597 }
620 {
621 /* -(A + B) -> (-B) - A. */
625 {
629 }
631 /* -(A + B) -> (-A) - B. */
633 {
637 }
638 }
642 /* - (A - B) -> B - A */
654 /* Fall through. */
658 {
667 }
673 /* In general we can't negate A / B, because if A is INT_MIN and
674 B is 1, we may turn this into INT_MIN / -1 which is undefined
675 and actually traps on some architectures. But if overflow is
676 undefined, we can negate, because - (INT_MIN / 1) is an
677 overflow. */
679 {
684 {
691 }
692 /* If overflow is undefined then we have to be careful because
693 we ask whether it's ok to associate the negate with the
694 division which is not ok for example for
695 -((a - b) / c) where (-(a - b)) / c may invoke undefined
696 overflow because of negating INT_MIN. So do not use
697 negate_expr_p here but open-code the two important cases. */
706 }
710 /* Convert -((double)float) into (double)(-float). */
712 {
716 }
720 /* Negate -f(x) as f(-x). */
723 {
729 }
733 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
735 {
738 {
745 }
746 }
751 }
754 }
756 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
757 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
758 return NULL_TREE. */
760 static tree
762 {
764 location_t loc;
777 }
778 \f
779 /* Split a tree IN into a constant, literal and variable parts that could be
780 combined with CODE to make IN. "constant" means an expression with
781 TREE_CONSTANT but that isn't an actual constant. CODE must be a
782 commutative arithmetic operation. Store the constant part into *CONP,
783 the literal in *LITP and return the variable part. If a part isn't
784 present, set it to null. If the tree does not decompose in this way,
785 return the entire tree as the variable part and the other parts as null.
787 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
788 case, we negate an operand that was subtracted. Except if it is a
789 literal for which we use *MINUS_LITP instead.
791 If NEGATE_P is true, we are negating all of IN, again except a literal
792 for which we use *MINUS_LITP instead.
794 If IN is itself a literal or constant, return it as appropriate.
796 Note that we do not guarantee that any of the three values will be the
797 same type as IN, but they will have the same signedness and mode. */
799 static tree
802 {
809 /* Strip any conversions that don't change the machine mode or signedness. */
818 /* We can associate addition and subtraction together (even
819 though the C standard doesn't say so) for integers because
820 the value is not affected. For reals, the value might be
821 affected, so we can't. */
824 {
830 /* First see if either of the operands is a literal, then a constant. */
843 /* If we haven't dealt with either operand, this is not a case we can
844 decompose. Otherwise, VAR is either of the ones remaining, if any. */
849 else
852 /* Now do any needed negations. */
859 }
862 {
863 /* -X - 1 is folded to ~X, undo that here. */
866 }
869 else
873 {
880 }
883 }
885 /* Re-associate trees split by the above function. T1 and T2 are
886 either expressions to associate or null. Return the new
887 expression, if any. LOC is the location of the new expression. If
888 we build an operation, do it in TYPE and with CODE. */
890 static tree
892 {
898 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
899 try to fold this since we will have infinite recursion. But do
900 deal with any NEGATE_EXPRs. */
903 {
905 {
918 }
920 {
923 }
927 }
931 }
932 \f
933 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
934 for use in int_const_binop, size_binop and size_diffop. */
936 static bool
938 {
945 {
954 }
959 }
962 /* Combine two integer constants ARG1 and ARG2 under operation CODE
963 to produce a new constant. Return NULL_TREE if we don't know how
964 to evaluate CODE at compile-time. */
966 static tree
969 {
970 wide_int res;
971 tree t;
980 {
996 {
1000 else
1002 }
1005 /* It's unclear from the C standard whether shifts can overflow.
1006 The following code ignores overflow; perhaps a C standard
1007 interpretation ruling is needed. */
1009 else
1016 {
1020 else
1022 }
1026 else
1105 }
1113 }
1115 tree
1117 {
1119 }
1121 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1122 constant. We assume ARG1 and ARG2 have the same data type, or at least
1123 are the same kind of constant and the same machine mode. Return zero if
1124 combining the constants is not allowed in the current operating mode. */
1126 static tree
1128 {
1129 /* Sanity check for the recursive cases. */
1137 {
1143 }
1146 {
1147 machine_mode mode;
1148 REAL_VALUE_TYPE d1;
1149 REAL_VALUE_TYPE d2;
1150 REAL_VALUE_TYPE value;
1151 REAL_VALUE_TYPE result;
1155 /* The following codes are handled by real_arithmetic. */
1157 {
1168 }
1176 /* Don't perform operation if we honor signaling NaNs and
1177 either operand is a NaN. */
1182 /* Don't perform operation if it would raise a division
1183 by zero exception. */
1189 /* If either operand is a NaN, just return it. Otherwise, set up
1190 for floating-point trap; we return an overflow. */
1199 /* Don't constant fold this floating point operation if
1200 the result has overflowed and flag_trapping_math. */
1208 /* Don't constant fold this floating point operation if the
1209 result may dependent upon the run-time rounding mode and
1210 flag_rounding_math is set, or if GCC's software emulation
1211 is unable to accurately represent the result. */
1221 }
1224 {
1225 FIXED_VALUE_TYPE f1;
1226 FIXED_VALUE_TYPE f2;
1227 FIXED_VALUE_TYPE result;
1232 /* The following codes are handled by fixed_arithmetic. */
1234 {
1246 {
1253 }
1258 }
1265 /* Propagate overflow flags. */
1269 }
1272 {
1281 {
1292 mpc_mul);
1306 mpc_div);
1307 /* Fallthru ... */
1313 {
1314 /* Keep this algorithm in sync with
1315 tree-complex.c:expand_complex_div_straight().
1317 Expand complex division to scalars, straightforward algorithm.
1318 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1319 t = br*br + bi*bi
1320 */
1321 tree magsquared
1325 tree t1
1329 tree t2
1336 }
1337 else
1338 {
1339 /* Keep this algorithm in sync with
1340 tree-complex.c:expand_complex_div_wide().
1342 Expand complex division to scalars, modified algorithm to minimize
1343 overflow with wide input ranges. */
1349 {
1350 /* In the TRUE branch, we compute
1351 ratio = br/bi;
1352 div = (br * ratio) + bi;
1353 tr = (ar * ratio) + ai;
1354 ti = (ai * ratio) - ar;
1355 tr = tr / div;
1356 ti = ti / div; */
1367 }
1368 else
1369 {
1370 /* In the FALSE branch, we compute
1371 ratio = d/c;
1372 divisor = (d * ratio) + c;
1373 tr = (b * ratio) + a;
1374 ti = b - (a * ratio);
1375 tr = tr / div;
1376 ti = ti / div; */
1388 }
1389 }
1394 }
1398 }
1402 {
1408 {
1414 /* It is possible that const_binop cannot handle the given
1415 code and return NULL_TREE */
1418 }
1421 }
1423 /* Shifts allow a scalar offset for a vector. */
1426 {
1432 {
1437 /* It is possible that const_binop cannot handle the given
1438 code and return NULL_TREE. */
1441 }
1444 }
1446 }
1448 /* Overload that adds a TYPE parameter to be able to dispatch
1449 to fold_relational_const. */
1451 tree
1453 {
1457 /* ??? Until we make the const_binop worker take the type of the
1458 result as argument put those cases that need it here. */
1460 {
1471 {
1487 {
1493 }
1496 }
1502 {
1527 {
1540 }
1543 }
1546 }
1548 /* Make sure type and arg0 have the same saturating flag. */
1552 }
1554 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1555 Return zero if computing the constants is not possible. */
1557 tree
1559 {
1561 {
1562 CASE_CONVERT:
1577 {
1578 /* Can't call fold_negate_const directly here as that doesn't
1579 handle all cases and we might not be able to negate some
1580 constants. */
1585 }
1594 {
1598 }
1604 /* Perform BIT_NOT_EXPR on each element individually. */
1606 {
1608 tree elem;
1613 {
1619 }
1622 }
1644 {
1663 else
1667 {
1671 }
1674 }
1679 {
1693 {
1698 }
1701 {
1705 }
1708 }
1712 }
1715 }
1717 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1718 indicates which particular sizetype to create. */
1720 tree
1722 {
1724 }
1725 \f
1726 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1727 is a tree code. The type of the result is taken from the operands.
1728 Both must be equivalent integer types, ala int_binop_types_match_p.
1729 If the operands are constant, so is the result. */
1731 tree
1733 {
1742 /* Handle the special case of two integer constants faster. */
1744 {
1745 /* And some specific cases even faster than that. */
1747 {
1752 }
1754 {
1757 }
1759 {
1762 }
1764 /* Handle general case of two integer constants. For sizetype
1765 constant calculations we always want to know about overflow,
1766 even in the unsigned case. */
1768 }
1771 }
1773 /* Given two values, either both of sizetype or both of bitsizetype,
1774 compute the difference between the two values. Return the value
1775 in signed type corresponding to the type of the operands. */
1777 tree
1779 {
1781 tree ctype;
1786 /* If the type is already signed, just do the simple thing. */
1794 else
1797 /* If either operand is not a constant, do the conversions to the signed
1798 type and subtract. The hardware will do the right thing with any
1799 overflow in the subtraction. */
1805 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1806 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1807 overflow) and negate (which can't either). Special-case a result
1808 of zero while we're here. */
1814 else
1818 MINUS_EXPR,
1820 }
1821 \f
1822 /* A subroutine of fold_convert_const handling conversions of an
1823 INTEGER_CST to another integer type. */
1825 static tree
1827 {
1828 /* Given an integer constant, make new constant with new type,
1829 appropriately sign-extended or truncated. Use widest_int
1830 so that any extension is done according ARG1's type. */
1834 }
1836 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1837 to an integer type. */
1839 static tree
1841 {
1843 tree t;
1845 /* The following code implements the floating point to integer
1846 conversion rules required by the Java Language Specification,
1847 that IEEE NaNs are mapped to zero and values that overflow
1848 the target precision saturate, i.e. values greater than
1849 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1850 are mapped to INT_MIN. These semantics are allowed by the
1851 C and C++ standards that simply state that the behavior of
1852 FP-to-integer conversion is unspecified upon overflow. */
1854 wide_int val;
1855 REAL_VALUE_TYPE r;
1859 {
1866 }
1868 /* If R is NaN, return zero and show we have an overflow. */
1870 {
1873 }
1875 /* See if R is less than the lower bound or greater than the
1876 upper bound. */
1879 {
1883 {
1886 }
1887 }
1890 {
1893 {
1896 {
1899 }
1900 }
1901 }
1908 }
1910 /* A subroutine of fold_convert_const handling conversions of a
1911 FIXED_CST to an integer type. */
1913 static tree
1915 {
1916 tree t;
1920 /* Right shift FIXED_CST to temp by fbit. */
1924 {
1926 HOST_BITS_PER_DOUBLE_INT,
1929 /* Left shift temp to temp_trunc by fbit. */
1931 HOST_BITS_PER_DOUBLE_INT,
1933 }
1934 else
1935 {
1938 }
1940 /* If FIXED_CST is negative, we need to round the value toward 0.
1941 By checking if the fractional bits are not zero to add 1 to temp. */
1947 /* Given a fixed-point constant, make new constant with new type,
1948 appropriately sign-extended or truncated. */
1956 }
1958 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1959 to another floating point type. */
1961 static tree
1963 {
1964 REAL_VALUE_TYPE value;
1965 tree t;
1970 /* If converting an infinity or NAN to a representation that doesn't
1971 have one, set the overflow bit so that we can produce some kind of
1972 error message at the appropriate point if necessary. It's not the
1973 most user-friendly message, but it's better than nothing. */
1980 /* Regular overflow, conversion produced an infinity in a mode that
1981 can't represent them. */
1986 else
1989 }
1991 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1992 to a floating point type. */
1994 static tree
1996 {
1997 REAL_VALUE_TYPE value;
1998 tree t;
2005 }
2007 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2008 to another fixed-point type. */
2010 static tree
2012 {
2013 FIXED_VALUE_TYPE value;
2014 tree t;
2021 /* Propagate overflow flags. */
2025 }
2027 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2028 to a fixed-point type. */
2030 static tree
2032 {
2033 FIXED_VALUE_TYPE value;
2034 tree t;
2036 double_int di;
2043 else
2051 /* Propagate overflow flags. */
2055 }
2057 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2058 to a fixed-point type. */
2060 static tree
2062 {
2063 FIXED_VALUE_TYPE value;
2064 tree t;
2072 /* Propagate overflow flags. */
2076 }
2078 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2079 type TYPE. If no simplification can be done return NULL_TREE. */
2081 static tree
2083 {
2089 {
2096 }
2098 {
2105 }
2107 {
2114 }
2116 }
2118 /* Construct a vector of zero elements of vector type TYPE. */
2120 static tree
2122 {
2123 tree t;
2127 }
2129 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2131 bool
2133 {
2148 {
2167 }
2168 }
2170 /* Convert expression ARG to type TYPE. Used by the middle-end for
2171 simple conversions in preference to calling the front-end's convert. */
2173 tree
2175 {
2177 tree tem;
2188 {
2191 /* Handle conversions between pointers to different address spaces. */
2196 /* fall through */
2201 {
2205 }
2219 {
2223 }
2225 {
2229 }
2231 {
2235 }
2238 {
2256 }
2261 {
2265 }
2268 {
2282 }
2286 {
2295 integer_zero_node));
2297 {
2301 {
2307 }
2315 }
2319 }
2337 }
2338 fold_convert_exit:
2341 }
2342 \f
2343 /* Return false if expr can be assumed not to be an lvalue, true
2344 otherwise. */
2346 static bool
2348 {
2349 /* We only need to wrap lvalue tree codes. */
2351 {
2382 /* Assume the worst for front-end tree codes. */
2386 }
2389 }
2391 /* Return an expr equal to X but certainly not valid as an lvalue. */
2393 tree
2395 {
2396 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2397 us. */
2404 }
2406 /* When pedantic, return an expr equal to X but certainly not valid as a
2407 pedantic lvalue. Otherwise, return X. */
2409 static tree
2411 {
2413 }
2414 \f
2415 /* Given a tree comparison code, return the code that is the logical inverse.
2416 It is generally not safe to do this for floating-point comparisons, except
2417 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2418 ERROR_MARK in this case. */
2420 enum tree_code
2422 {
2428 {
2459 }
2460 }
2462 /* Similar, but return the comparison that results if the operands are
2463 swapped. This is safe for floating-point. */
2465 enum tree_code
2467 {
2469 {
2495 }
2496 }
2499 /* Convert a comparison tree code from an enum tree_code representation
2500 into a compcode bit-based encoding. This function is the inverse of
2501 compcode_to_comparison. */
2503 static enum comparison_code
2505 {
2507 {
2538 }
2539 }
2541 /* Convert a compcode bit-based encoding of a comparison operator back
2542 to GCC's enum tree_code representation. This function is the
2543 inverse of comparison_to_compcode. */
2545 static enum tree_code
2547 {
2549 {
2580 }
2581 }
2583 /* Return a tree for the comparison which is the combination of
2584 doing the AND or OR (depending on CODE) of the two operations LCODE
2585 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2586 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2587 if this makes the transformation invalid. */
2589 tree
2594 {
2601 {
2612 }
2615 {
2616 /* Eliminate unordered comparisons, as well as LTGT and ORD
2617 which are not used unless the mode has NaNs. */
2623 }
2625 {
2626 /* Check that the original operation and the optimized ones will trap
2627 under the same condition. */
2638 /* In a short-circuited boolean expression the LHS might be
2639 such that the RHS, if evaluated, will never trap. For
2640 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2641 if neither x nor y is NaN. (This is a mixed blessing: for
2642 example, the expression above will never trap, hence
2643 optimizing it to x < y would be invalid). */
2648 /* If the comparison was short-circuited, and only the RHS
2649 trapped, we may now generate a spurious trap. */
2654 /* If we changed the conditions that cause a trap, we lose. */
2657 }
2663 else
2664 {
2669 }
2670 }
2671 \f
2672 /* Return nonzero if two operands (typically of the same tree node)
2673 are necessarily equal. If either argument has side-effects this
2674 function returns zero. FLAGS modifies behavior as follows:
2676 If OEP_ONLY_CONST is set, only return nonzero for constants.
2677 This function tests whether the operands are indistinguishable;
2678 it does not test whether they are equal using C's == operation.
2679 The distinction is important for IEEE floating point, because
2680 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2681 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2683 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2684 even though it may hold multiple values during a function.
2685 This is because a GCC tree node guarantees that nothing else is
2686 executed between the evaluation of its "operands" (which may often
2687 be evaluated in arbitrary order). Hence if the operands themselves
2688 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2689 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2690 unset means assuming isochronic (or instantaneous) tree equivalence.
2691 Unless comparing arbitrary expression trees, such as from different
2692 statements, this flag can usually be left unset.
2694 If OEP_PURE_SAME is set, then pure functions with identical arguments
2695 are considered the same. It is used when the caller has other ways
2696 to ensure that global memory is unchanged in between. */
2698 int
2700 {
2701 /* If either is ERROR_MARK, they aren't equal. */
2707 /* Similar, if either does not have a type (like a released SSA name),
2708 they aren't equal. */
2712 /* Check equality of integer constants before bailing out due to
2713 precision differences. */
2717 /* If both types don't have the same signedness, then we can't consider
2718 them equal. We must check this before the STRIP_NOPS calls
2719 because they may change the signedness of the arguments. As pointers
2720 strictly don't have a signedness, require either two pointers or
2721 two non-pointers as well. */
2726 /* We cannot consider pointers to different address space equal. */
2732 /* If both types don't have the same precision, then it is not safe
2733 to strip NOPs. */
2741 /* In case both args are comparisons but with different comparison
2742 code, try to swap the comparison operands of one arg to produce
2743 a match and compare that variant. */
2747 {
2755 }
2758 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2762 /* This is needed for conversions and for COMPONENT_REF.
2763 Might as well play it safe and always test this. */
2769 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2770 We don't care about side effects in that case because the SAVE_EXPR
2771 takes care of that for us. In all other cases, two expressions are
2772 equal if they have no side effects. If we have two identical
2773 expressions with side effects that should be treated the same due
2774 to the only side effects being identical SAVE_EXPR's, that will
2775 be detected in the recursive calls below.
2776 If we are taking an invariant address of two identical objects
2777 they are necessarily equal as well. */
2784 /* Next handle constant cases, those for which we can return 1 even
2785 if ONLY_CONST is set. */
2788 {
2803 {
2804 /* If we do not distinguish between signed and unsigned zero,
2805 consider them equal. */
2808 }
2812 {
2819 {
2823 }
2825 }
2829 flags)
2831 flags));
2845 }
2850 /* Define macros to test an operand from arg0 and arg1 for equality and a
2851 variant that allows null and views null as being different from any
2852 non-null value. In the latter case, if either is null, the both
2853 must be; otherwise, do the normal comparison. */
2854 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2855 TREE_OPERAND (arg1, N), flags)
2857 #define OP_SAME_WITH_NULL(N) \
2858 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2859 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2862 {
2864 /* Two conversions are equal only if signedness and modes match. */
2866 {
2867 CASE_CONVERT:
2875 }
2885 /* For commutative ops, allow the other order. */
2893 /* If either of the pointer (or reference) expressions we are
2894 dereferencing contain a side effect, these cannot be equal,
2895 but their addresses can be. */
2902 {
2913 /* Require equal extra operands and then fall through to MEM_REF
2914 handling of the two common operands. */
2919 /* Fallthru. */
2922 /* Require equal access sizes, and similar pointer types.
2923 We can have incomplete types for array references of
2924 variable-sized arrays from the Fortran frontend
2925 though. Also verify the types are compatible. */
2932 && alias_ptr_types_compatible_p
2939 /* Operands 2 and 3 may be null.
2940 Compare the array index by value if it is constant first as we
2941 may have different types but same value here. */
2952 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2953 may be NULL when we're called to compare MEM_EXPRs. */
2968 }
2972 {
2986 /* The multiplcation operands are commutative. */
2987 /* FALLTHRU */
2995 /* Otherwise take into account this is a commutative operation. */
3008 }
3012 {
3014 /* If the CALL_EXPRs call different functions, then they
3015 clearly can not be equal. */
3017 flags))
3020 {
3024 else
3028 }
3030 /* Now see if all the arguments are the same. */
3031 {
3042 /* If we get here and both argument lists are exhausted
3043 then the CALL_EXPRs are equal. */
3045 }
3048 }
3051 /* Consider __builtin_sqrt equal to sqrt. */
3059 }
3061 #undef OP_SAME
3062 #undef OP_SAME_WITH_NULL
3063 }
3064 \f
3065 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3066 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3068 When in doubt, return 0. */
3070 static int
3072 {
3084 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3085 and see if the inner values are the same. This removes any
3086 signedness comparison, which doesn't matter here. */
3093 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3094 actual comparison operand, ARG0.
3096 First throw away any conversions to wider types
3097 already present in the operands. */
3106 {
3109 /* Make sure shorter operand is extended the right way
3110 to match the longer operand. */
3116 }
3119 }
3120 \f
3121 /* See if ARG is an expression that is either a comparison or is performing
3122 arithmetic on comparisons. The comparisons must only be comparing
3123 two different values, which will be stored in *CVAL1 and *CVAL2; if
3124 they are nonzero it means that some operands have already been found.
3125 No variables may be used anywhere else in the expression except in the
3126 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3127 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3129 If this is true, return 1. Otherwise, return zero. */
3131 static int
3133 {
3137 /* We can handle some of the tcc_expression cases here. */
3147 {
3148 /* If we've already found a CVAL1 or CVAL2, this expression is
3149 two complex to handle. */
3155 }
3158 {
3181 /* First see if we can handle the first operand, then the second. For
3182 the second operand, we know *CVAL1 can't be zero. It must be that
3183 one side of the comparison is each of the values; test for the
3184 case where this isn't true by failing if the two operands
3185 are the same. */
3194 ;
3198 ;
3199 else
3203 ;
3207 ;
3208 else
3215 }
3216 }
3217 \f
3218 /* ARG is a tree that is known to contain just arithmetic operations and
3219 comparisons. Evaluate the operations in the tree substituting NEW0 for
3220 any occurrence of OLD0 as an operand of a comparison and likewise for
3221 NEW1 and OLD1. */
3223 static tree
3226 {
3231 /* We can handle some of the tcc_expression cases here. */
3239 {
3254 {
3273 }
3274 /* Fall through - ??? */
3277 {
3281 /* We need to check both for exact equality and tree equality. The
3282 former will be true if the operand has a side-effect. In that
3283 case, we know the operand occurred exactly once. */
3296 }
3300 }
3301 }
3302 \f
3303 /* Return a tree for the case when the result of an expression is RESULT
3304 converted to TYPE and OMITTED was previously an operand of the expression
3305 but is now not needed (e.g., we folded OMITTED * 0).
3307 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3308 the conversion of RESULT to TYPE. */
3310 tree
3312 {
3315 /* If the resulting operand is an empty statement, just return the omitted
3316 statement casted to void. */
3326 }
3328 /* Return a tree for the case when the result of an expression is RESULT
3329 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3330 of the expression but are now not needed.
3332 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3333 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3334 evaluated before OMITTED2. Otherwise, if neither has side effects,
3335 just do the conversion of RESULT to TYPE. */
3337 tree
3340 {
3349 }
3351 \f
3352 /* Return a simplified tree node for the truth-negation of ARG. This
3353 never alters ARG itself. We assume that ARG is an operation that
3354 returns a truth value (0 or 1).
3356 FIXME: one would think we would fold the result, but it causes
3357 problems with the dominator optimizer. */
3359 static tree
3361 {
3366 /* If this is a comparison, we can simply invert it, except for
3367 floating-point non-equality comparisons, in which case we just
3368 enclose a TRUTH_NOT_EXPR around what we have. */
3371 {
3374 && flag_trapping_math
3385 }
3388 {
3407 /* Here we can invert either operand. We invert the first operand
3408 unless the second operand is a TRUTH_NOT_EXPR in which case our
3409 result is the XOR of the first operand with the inside of the
3410 negation of the second operand. */
3415 else
3438 {
3445 /* A COND_EXPR may have a throw as one operand, which
3446 then has void type. Just leave void operands
3447 as they are. */
3453 }
3465 CASE_CONVERT:
3469 /* ... fall through ... */
3491 }
3492 }
3494 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3495 assume that ARG is an operation that returns a truth value (0 or 1
3496 for scalars, 0 or -1 for vectors). Return the folded expression if
3497 folding is successful. Otherwise, return NULL_TREE. */
3499 static tree
3501 {
3504 ? BIT_NOT_EXPR
3507 }
3509 /* Return a simplified tree node for the truth-negation of ARG. This
3510 never alters ARG itself. We assume that ARG is an operation that
3511 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3513 tree
3515 {
3521 ? BIT_NOT_EXPR
3524 }
3526 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3527 operands are another bit-wise operation with a common input. If so,
3528 distribute the bit operations to save an operation and possibly two if
3529 constants are involved. For example, convert
3530 (A | B) & (A | C) into A | (B & C)
3531 Further simplification will occur if B and C are constants.
3533 If this optimization cannot be done, 0 will be returned. */
3535 static tree
3538 {
3539 tree common;
3549 {
3553 }
3555 {
3559 }
3561 {
3565 }
3567 {
3571 }
3572 else
3580 }
3582 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3583 with code CODE. This optimization is unsafe. */
3584 static tree
3587 {
3591 /* (A / C) +- (B / C) -> (A +- B) / C. */
3601 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3606 {
3618 }
3621 }
3622 \f
3623 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3624 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3626 static tree
3629 {
3633 {
3640 }
3654 }
3656 /* Optimize a bit-field compare.
3658 There are two cases: First is a compare against a constant and the
3659 second is a comparison of two items where the fields are at the same
3660 bit position relative to the start of a chunk (byte, halfword, word)
3661 large enough to contain it. In these cases we can avoid the shift
3662 implicit in bitfield extractions.
3664 For constants, we emit a compare of the shifted constant with the
3665 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3666 compared. For two fields at the same position, we do the ANDs with the
3667 similar mask and compare the result of the ANDs.
3669 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3670 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3671 are the left and right operands of the comparison, respectively.
3673 If the optimization described above can be done, we return the resulting
3674 tree. Otherwise we return zero. */
3676 static tree
3679 {
3682 tree unsigned_type;
3688 tree mask;
3689 tree offset;
3691 /* Get all the information about the extractions being done. If the bit size
3692 if the same as the size of the underlying object, we aren't doing an
3693 extraction at all and so can do nothing. We also don't want to
3694 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3695 then will no longer be able to replace it. */
3703 {
3704 /* If this is not a constant, we can only do something if bit positions,
3705 sizes, and signedness are the same. */
3713 }
3715 /* See if we can find a mode to refer to this field. We should be able to,
3716 but fail if we can't. */
3725 /* Set signed and unsigned types of the precision of this mode for the
3726 shifts below. */
3729 /* Compute the bit position and size for the new reference and our offset
3730 within it. If the new reference is the same size as the original, we
3731 won't optimize anything, so return zero. */
3741 /* Make the mask to be used against the extracted field. */
3748 /* If not comparing with constant, just rework the comparison
3749 and return. */
3753 unsigned_type,
3756 mask),
3759 unsigned_type,
3762 mask));
3764 /* Otherwise, we are handling the constant case. See if the constant is too
3765 big for the field. Warn and return a tree of for 0 (false) if so. We do
3766 this not only for its own sake, but to avoid having to test for this
3767 error case below. If we didn't, we might generate wrong code.
3769 For unsigned fields, the constant shifted right by the field length should
3770 be all zero. For signed fields, the high-order bits should agree with
3771 the sign bit. */
3774 {
3776 {
3780 }
3781 }
3782 else
3783 {
3786 {
3790 }
3791 }
3793 /* Single-bit compares should always be against zero. */
3795 {
3798 }
3800 /* Make a new bitfield reference, shift the constant over the
3801 appropriate number of bits and mask it with the computed mask
3802 (in case this was a signed field). If we changed it, make a new one. */
3809 mask);
3814 }
3815 \f
3816 /* Subroutine for fold_truth_andor_1: decode a field reference.
3818 If EXP is a comparison reference, we return the innermost reference.
3820 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3821 set to the starting bit number.
3823 If the innermost field can be completely contained in a mode-sized
3824 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3826 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3827 otherwise it is not changed.
3829 *PUNSIGNEDP is set to the signedness of the field.
3831 *PMASK is set to the mask used. This is either contained in a
3832 BIT_AND_EXPR or derived from the width of the field.
3834 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3836 Return 0 if this is not a component reference or is one that we can't
3837 do anything with. */
3839 static tree
3844 {
3848 tree unsigned_type;
3851 /* All the optimizations using this function assume integer fields.
3852 There are problems with FP fields since the type_for_size call
3853 below can fail for, e.g., XFmode. */
3857 /* We are interested in the bare arrangement of bits, so strip everything
3858 that doesn't affect the machine mode. However, record the type of the
3859 outermost expression if it may matter below. */
3866 {
3872 }
3881 /* If the number of bits in the reference is the same as the bitsize of
3882 the outer type, then the outer type gives the signedness. Otherwise
3883 (in case of a small bitfield) the signedness is unchanged. */
3887 /* Compute the mask to access the bitfield. */
3896 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3904 }
3906 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3907 bit positions and MASK is SIGNED. */
3909 static int
3911 {
3915 /* If this function returns true when the type of the mask is
3916 UNSIGNED, then there will be errors. In particular see
3917 gcc.c-torture/execute/990326-1.c. There does not appear to be
3918 any documentation paper trail as to why this is so. But the pre
3919 wide-int worked with that restriction and it has been preserved
3920 here. */
3925 }
3927 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3928 represents the sign bit of EXP's type. If EXP represents a sign
3929 or zero extension, also test VAL against the unextended type.
3930 The return value is the (sub)expression whose sign bit is VAL,
3931 or NULL_TREE otherwise. */
3933 tree
3935 {
3937 tree t;
3939 /* Tree EXP must have an integral type. */
3944 /* Tree VAL must be an integer constant. */
3953 /* Handle extension from a narrower type. */
3959 }
3961 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3962 to be evaluated unconditionally. */
3964 static int
3966 {
3967 /* Strip any conversions that don't change the machine mode. */
3976 /* Don't regard global variables as simple. They may be
3977 allocated in ways unknown to the compiler (shared memory,
3978 #pragma weak, etc). */
3981 /* Weakrefs are not safe to be read, since they can be NULL.
3982 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3983 have DECL_WEAK flag set. */
3985 /* Loading a static variable is unduly expensive, but global
3986 registers aren't expensive. */
3988 }
3990 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3991 to be evaluated unconditionally.
3992 I addition to simple_operand_p, we assume that comparisons, conversions,
3993 and logic-not operations are simple, if their operands are simple, too. */
3995 static bool
3997 {
4017 }
4019 \f
4020 /* The following functions are subroutines to fold_range_test and allow it to
4021 try to change a logical combination of comparisons into a range test.
4023 For example, both
4024 X == 2 || X == 3 || X == 4 || X == 5
4025 and
4026 X >= 2 && X <= 5
4027 are converted to
4028 (unsigned) (X - 2) <= 3
4030 We describe each set of comparisons as being either inside or outside
4031 a range, using a variable named like IN_P, and then describe the
4032 range with a lower and upper bound. If one of the bounds is omitted,
4033 it represents either the highest or lowest value of the type.
4035 In the comments below, we represent a range by two numbers in brackets
4036 preceded by a "+" to designate being inside that range, or a "-" to
4037 designate being outside that range, so the condition can be inverted by
4038 flipping the prefix. An omitted bound is represented by a "-". For
4039 example, "- [-, 10]" means being outside the range starting at the lowest
4040 possible value and ending at 10, in other words, being greater than 10.
4041 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4042 always false.
4044 We set up things so that the missing bounds are handled in a consistent
4045 manner so neither a missing bound nor "true" and "false" need to be
4046 handled using a special case. */
4048 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4049 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4050 and UPPER1_P are nonzero if the respective argument is an upper bound
4051 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4052 must be specified for a comparison. ARG1 will be converted to ARG0's
4053 type if both are specified. */
4055 static tree
4058 {
4059 tree tem;
4063 /* If neither arg represents infinity, do the normal operation.
4064 Else, if not a comparison, return infinity. Else handle the special
4065 comparison rules. Note that most of the cases below won't occur, but
4066 are handled for consistency. */
4069 {
4074 }
4079 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4080 for neither. In real maths, we cannot assume open ended ranges are
4081 the same. But, this is computer arithmetic, where numbers are finite.
4082 We can therefore make the transformation of any unbounded range with
4083 the value Z, Z being greater than any representable number. This permits
4084 us to treat unbounded ranges as equal. */
4088 {
4109 }
4112 }
4113 \f
4114 /* Helper routine for make_range. Perform one step for it, return
4115 new expression if the loop should continue or NULL_TREE if it should
4116 stop. */
4118 tree
4122 {
4128 {
4130 /* We can only do something if the range is testing for zero. */
4139 /* We can only do something if the range is testing for zero
4140 and if the second operand is an integer constant. Note that
4141 saying something is "in" the range we make is done by
4142 complementing IN_P since it will set in the initial case of
4143 being not equal to zero; "out" is leaving it alone. */
4150 {
4171 }
4173 /* If this is an unsigned comparison, we also know that EXP is
4174 greater than or equal to zero. We base the range tests we make
4175 on that fact, so we record it here so we can parse existing
4176 range tests. We test arg0_type since often the return type
4177 of, e.g. EQ_EXPR, is boolean. */
4179 {
4183 NULL_TREE))
4188 /* If the high bound is missing, but we have a nonzero low
4189 bound, reverse the range so it goes from zero to the low bound
4190 minus 1. */
4192 {
4197 }
4198 }
4206 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4207 low and high are non-NULL, then normalize will DTRT. */
4210 {
4215 }
4217 /* (-x) IN [a,b] -> x in [-b, -a] */
4229 /* ~ X -> -X - 1 */
4238 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4239 move a constant to the other side. */
4244 /* If EXP is signed, any overflow in the computation is undefined,
4245 so we don't worry about it so long as our computations on
4246 the bounds don't overflow. For unsigned, overflow is defined
4247 and this is exactly the right thing. */
4259 normalize:
4260 /* Check for an unsigned range which has wrapped around the maximum
4261 value thus making n_high < n_low, and normalize it. */
4263 {
4269 /* If the range is of the form +/- [ x+1, x ], we won't
4270 be able to normalize it. But then, it represents the
4271 whole range or the empty set, so make it
4272 +/- [ -, - ]. */
4276 else
4278 }
4279 else
4287 CASE_CONVERT:
4305 /* If we're converting arg0 from an unsigned type, to exp,
4306 a signed type, we will be doing the comparison as unsigned.
4307 The tests above have already verified that LOW and HIGH
4308 are both positive.
4310 So we have to ensure that we will handle large unsigned
4311 values the same way that the current signed bounds treat
4312 negative values. */
4315 {
4316 tree high_positive;
4317 tree equiv_type;
4318 /* For fixed-point modes, we need to pass the saturating flag
4319 as the 2nd parameter. */
4321 equiv_type
4324 else
4325 equiv_type
4328 /* A range without an upper bound is, naturally, unbounded.
4329 Since convert would have cropped a very large value, use
4330 the max value for the destination type. */
4331 high_positive
4338 high_positive),
4341 /* If the low bound is specified, "and" the range with the
4342 range for which the original unsigned value will be
4343 positive. */
4345 {
4348 integer_zero_node),
4349 high_positive))
4353 }
4354 else
4355 {
4356 /* Otherwise, "or" the range with the range of the input
4357 that will be interpreted as negative. */
4360 integer_zero_node),
4361 high_positive))
4365 }
4366 }
4375 }
4376 }
4378 /* Given EXP, a logical expression, set the range it is testing into
4379 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4380 actually being tested. *PLOW and *PHIGH will be made of the same
4381 type as the returned expression. If EXP is not a comparison, we
4382 will most likely not be returning a useful value and range. Set
4383 *STRICT_OVERFLOW_P to true if the return value is only valid
4384 because signed overflow is undefined; otherwise, do not change
4385 *STRICT_OVERFLOW_P. */
4387 tree
4390 {
4398 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4399 and see if we can refine the range. Some of the cases below may not
4400 happen, but it doesn't seem worth worrying about this. We "continue"
4401 the outer loop when we've changed something; otherwise we "break"
4402 the switch, which will "break" the while. */
4408 {
4414 {
4422 }
4431 }
4433 /* If EXP is a constant, we can evaluate whether this is true or false. */
4435 {
4442 }
4446 }
4447 \f
4448 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4449 type, TYPE, return an expression to test if EXP is in (or out of, depending
4450 on IN_P) the range. Return 0 if the test couldn't be created. */
4452 tree
4455 {
4458 #ifdef HAVE_canonicalize_funcptr_for_compare
4459 /* Disable this optimization for function pointer expressions
4460 on targets that require function pointer canonicalization. */
4465 #endif
4468 {
4474 }
4492 {
4494 {
4498 }
4500 }
4502 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4504 {
4508 {
4510 {
4513 etype
4515 else
4518 }
4521 }
4522 }
4524 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4525 This requires wrap-around arithmetics for the type of the expression.
4526 First make sure that arithmetics in this type is valid, then make sure
4527 that it wraps around. */
4533 {
4536 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4537 for the type in question, as we rely on this here. */
4547 else
4549 }
4559 {
4561 {
4566 }
4568 }
4576 }
4577 \f
4578 /* Return the predecessor of VAL in its type, handling the infinite case. */
4580 static tree
4582 {
4588 else
4591 }
4593 /* Return the successor of VAL in its type, handling the infinite case. */
4595 static tree
4597 {
4603 else
4606 }
4608 /* Given two ranges, see if we can merge them into one. Return 1 if we
4609 can, 0 if we can't. Set the output range into the specified parameters. */
4611 bool
4614 {
4618 tree tem;
4628 /* Make range 0 be the range that starts first, or ends last if they
4629 start at the same value. Swap them if it isn't. */
4632 || (lowequal
4635 {
4639 }
4641 /* Now flag two cases, whether the ranges are disjoint or whether the
4642 second range is totally subsumed in the first. Note that the tests
4643 below are simplified by the ones above. */
4649 /* We now have four cases, depending on whether we are including or
4650 excluding the two ranges. */
4652 {
4653 /* If they don't overlap, the result is false. If the second range
4654 is a subset it is the result. Otherwise, the range is from the start
4655 of the second to the end of the first. */
4660 else
4662 }
4665 {
4666 /* If they don't overlap, the result is the first range. If they are
4667 equal, the result is false. If the second range is a subset of the
4668 first, and the ranges begin at the same place, we go from just after
4669 the end of the second range to the end of the first. If the second
4670 range is not a subset of the first, or if it is a subset and both
4671 ranges end at the same place, the range starts at the start of the
4672 first range and ends just before the second range.
4673 Otherwise, we can't describe this as a single range. */
4679 {
4684 {
4685 /* We are in the weird situation where high0 > high1 but
4686 high1 has no successor. Punt. */
4688 }
4689 }
4691 {
4696 {
4697 /* low0 < low1 but low1 has no predecessor. Punt. */
4699 }
4700 }
4701 else
4703 }
4706 {
4707 /* If they don't overlap, the result is the second range. If the second
4708 is a subset of the first, the result is false. Otherwise,
4709 the range starts just after the first range and ends at the
4710 end of the second. */
4715 else
4716 {
4721 {
4722 /* high1 > high0 but high0 has no successor. Punt. */
4724 }
4725 }
4726 }
4728 else
4729 {
4730 /* The case where we are excluding both ranges. Here the complex case
4731 is if they don't overlap. In that case, the only time we have a
4732 range is if they are adjacent. If the second is a subset of the
4733 first, the result is the first. Otherwise, the range to exclude
4734 starts at the beginning of the first range and ends at the end of the
4735 second. */
4737 {
4742 else
4743 {
4744 /* Canonicalize - [min, x] into - [-, x]. */
4747 {
4752 /* FALLTHROUGH */
4765 }
4767 /* Canonicalize - [x, max] into - [x, -]. */
4770 {
4775 /* FALLTHROUGH */
4791 }
4793 /* The ranges might be also adjacent between the maximum and
4794 minimum values of the given type. For
4795 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4796 return + [x + 1, y - 1]. */
4798 {
4805 }
4806 else
4808 }
4809 }
4812 else
4814 }
4818 }
4819 \f
4821 /* Subroutine of fold, looking inside expressions of the form
4822 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4823 of the COND_EXPR. This function is being used also to optimize
4824 A op B ? C : A, by reversing the comparison first.
4826 Return a folded expression whose code is not a COND_EXPR
4827 anymore, or NULL_TREE if no folding opportunity is found. */
4829 static tree
4832 {
4837 tree tem;
4842 /* If we have A op 0 ? A : -A, consider applying the following
4843 transformations:
4845 A == 0? A : -A same as -A
4846 A != 0? A : -A same as A
4847 A >= 0? A : -A same as abs (A)
4848 A > 0? A : -A same as abs (A)
4849 A <= 0? A : -A same as -abs (A)
4850 A < 0? A : -A same as -abs (A)
4852 None of these transformations work for modes with signed
4853 zeros. If A is +/-0, the first two transformations will
4854 change the sign of the result (from +0 to -0, or vice
4855 versa). The last four will fix the sign of the result,
4856 even though the original expressions could be positive or
4857 negative, depending on the sign of A.
4859 Note that all these transformations are correct if A is
4860 NaN, since the two alternatives (A and -A) are also NaNs. */
4867 /* In the case that A is of the form X-Y, '-A' (arg2) may
4868 have already been folded to Y-X, check for that. */
4876 {
4890 /* Fall through. */
4912 }
4914 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4915 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4916 both transformations are correct when A is NaN: A != 0
4917 is then true, and A == 0 is false. */
4921 {
4926 }
4928 /* Try some transformations of A op B ? A : B.
4930 A == B? A : B same as B
4931 A != B? A : B same as A
4932 A >= B? A : B same as max (A, B)
4933 A > B? A : B same as max (B, A)
4934 A <= B? A : B same as min (A, B)
4935 A < B? A : B same as min (B, A)
4937 As above, these transformations don't work in the presence
4938 of signed zeros. For example, if A and B are zeros of
4939 opposite sign, the first two transformations will change
4940 the sign of the result. In the last four, the original
4941 expressions give different results for (A=+0, B=-0) and
4942 (A=-0, B=+0), but the transformed expressions do not.
4944 The first two transformations are correct if either A or B
4945 is a NaN. In the first transformation, the condition will
4946 be false, and B will indeed be chosen. In the case of the
4947 second transformation, the condition A != B will be true,
4948 and A will be chosen.
4950 The conversions to max() and min() are not correct if B is
4951 a number and A is not. The conditions in the original
4952 expressions will be false, so all four give B. The min()
4953 and max() versions would give a NaN instead. */
4956 /* Avoid these transformations if the COND_EXPR may be used
4957 as an lvalue in the C++ front-end. PR c++/19199. */
4958 && (in_gimple_form
4964 {
4969 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4971 {
4975 }
4978 {
4987 /* In C++ a ?: expression can be an lvalue, so put the
4988 operand which will be used if they are equal first
4989 so that we can convert this back to the
4990 corresponding COND_EXPR. */
4992 {
5001 }
5008 {
5017 }
5032 }
5033 }
5035 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5036 we might still be able to simplify this. For example,
5037 if C1 is one less or one more than C2, this might have started
5038 out as a MIN or MAX and been transformed by this function.
5039 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5045 {
5049 /* We can replace A with C1 in this case. */
5054 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5055 MIN_EXPR, to preserve the signedness of the comparison. */
5057 OEP_ONLY_CONST)
5061 OEP_ONLY_CONST))
5062 {
5065 arg2));
5068 }
5072 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5073 as above. */
5075 OEP_ONLY_CONST)
5079 OEP_ONLY_CONST))
5080 {
5083 arg2));
5086 }
5090 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5091 MAX_EXPR, to preserve the signedness of the comparison. */
5093 OEP_ONLY_CONST)
5097 OEP_ONLY_CONST))
5098 {
5101 arg2));
5103 }
5107 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5109 OEP_ONLY_CONST)
5113 OEP_ONLY_CONST))
5114 {
5117 arg2));
5119 }
5125 }
5128 }
5131 \f
5132 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5133 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5134 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5135 false) >= 2)
5136 #endif
5138 /* EXP is some logical combination of boolean tests. See if we can
5139 merge it into some range test. Return the new tree if so. */
5141 static tree
5144 {
5160 /* If this is an OR operation, invert both sides; we will invert
5161 again at the end. */
5165 /* If both expressions are the same, if we can merge the ranges, and we
5166 can build the range test, return it or it inverted. If one of the
5167 ranges is always true or always false, consider it to be the same
5168 expression as the other. */
5176 {
5180 }
5182 /* On machines where the branch cost is expensive, if this is a
5183 short-circuited branch and the underlying object on both sides
5184 is the same, make a non-short-circuit operation. */
5190 {
5191 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5192 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5193 which cases we can't do this. */
5201 {
5210 {
5213 WARN_STRICT_OVERFLOW_COMPARISON);
5217 }
5218 }
5219 }
5222 }
5223 \f
5224 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5225 bit value. Arrange things so the extra bits will be set to zero if and
5226 only if C is signed-extended to its full width. If MASK is nonzero,
5227 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5229 static tree
5231 {
5234 tree temp;
5239 /* We work by getting just the sign bit into the low-order bit, then
5240 into the high-order bit, then sign-extend. We then XOR that value
5241 with C. */
5244 /* We must use a signed type in order to get an arithmetic right shift.
5245 However, we must also avoid introducing accidental overflows, so that
5246 a subsequent call to integer_zerop will work. Hence we must
5247 do the type conversion here. At this point, the constant is either
5248 zero or one, and the conversion to a signed type can never overflow.
5249 We could get an overflow if this conversion is done anywhere else. */
5258 /* If necessary, convert the type back to match the type of C. */
5263 }
5264 \f
5265 /* For an expression that has the form
5266 (A && B) || ~B
5267 or
5268 (A || B) && ~B,
5269 we can drop one of the inner expressions and simplify to
5270 A || ~B
5271 or
5272 A && ~B
5273 LOC is the location of the resulting expression. OP is the inner
5274 logical operation; the left-hand side in the examples above, while CMPOP
5275 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5276 removing a condition that guards another, as in
5277 (A != NULL && A->...) || A == NULL
5278 which we must not transform. If RHS_ONLY is true, only eliminate the
5279 right-most operand of the inner logical operation. */
5281 static tree
5284 {
5302 {
5305 {
5308 }
5309 }
5311 {
5314 {
5317 }
5318 }
5333 }
5335 /* Find ways of folding logical expressions of LHS and RHS:
5336 Try to merge two comparisons to the same innermost item.
5337 Look for range tests like "ch >= '0' && ch <= '9'".
5338 Look for combinations of simple terms on machines with expensive branches
5339 and evaluate the RHS unconditionally.
5341 For example, if we have p->a == 2 && p->b == 4 and we can make an
5342 object large enough to span both A and B, we can do this with a comparison
5343 against the object ANDed with the a mask.
5345 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5346 operations to do this with one comparison.
5348 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5349 function and the one above.
5351 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5352 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5354 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5355 two operands.
5357 We return the simplified tree or 0 if no optimization is possible. */
5359 static tree
5362 {
5363 /* If this is the "or" of two comparisons, we can do something if
5364 the comparisons are NE_EXPR. If this is the "and", we can do something
5365 if the comparisons are EQ_EXPR. I.e.,
5366 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5368 WANTED_CODE is this operation code. For single bit fields, we can
5369 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5370 comparison for one-bit fields. */
5390 /* Start by getting the comparison codes. Fail if anything is volatile.
5391 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5392 it were surrounded with a NE_EXPR. */
5401 {
5405 }
5408 {
5412 }
5423 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5426 {
5429 {
5434 }
5437 {
5443 }
5444 }
5449 /* If the RHS can be evaluated unconditionally and its operands are
5450 simple, it wins to evaluate the RHS unconditionally on machines
5451 with expensive branches. In this case, this isn't a comparison
5452 that can be merged. */
5459 {
5460 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5471 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5481 }
5483 /* See if the comparisons can be merged. Then get all the parameters for
5484 each side. */
5508 /* It must be true that the inner operation on the lhs of each
5509 comparison must be the same if we are to be able to do anything.
5510 Then see if we have constants. If not, the same must be true for
5511 the rhs's. */
5522 else
5525 /* If either comparison code is not correct for our logical operation,
5526 fail. However, we can convert a one-bit comparison against zero into
5527 the opposite comparison against that bit being set in the field. */
5531 {
5533 {
5534 /* Make the left operand unsigned, since we are only interested
5535 in the value of one bit. Otherwise we are doing the wrong
5536 thing below. */
5539 }
5540 else
5542 }
5544 /* This is analogous to the code for l_const above. */
5546 {
5548 {
5551 }
5552 else
5554 }
5556 /* See if we can find a mode that contains both fields being compared on
5557 the left. If we can't, fail. Otherwise, update all constants and masks
5558 to be relative to a field of that size. */
5563 volatilep);
5573 {
5576 }
5584 {
5591 {
5595 }
5596 }
5598 {
5605 {
5609 }
5610 }
5612 /* If the right sides are not constant, do the same for it. Also,
5613 disallow this optimization if a size or signedness mismatch occurs
5614 between the left and right sides. */
5616 {
5619 /* Make sure the two fields on the right
5620 correspond to the left without being swapped. */
5628 volatilep);
5638 {
5641 }
5650 /* Make a mask that corresponds to both fields being compared.
5651 Do this for both items being compared. If the operands are the
5652 same size and the bits being compared are in the same position
5653 then we can do this by masking both and comparing the masked
5654 results. */
5658 {
5670 }
5672 /* There is still another way we can do something: If both pairs of
5673 fields being compared are adjacent, we may be able to make a wider
5674 field containing them both.
5676 Note that we still must mask the lhs/rhs expressions. Furthermore,
5677 the mask must be shifted to account for the shift done by
5678 make_bit_field_ref. */
5683 {
5684 tree type;
5698 /* Convert to the smaller type before masking out unwanted bits. */
5701 {
5703 {
5707 }
5709 {
5713 }
5714 }
5723 }
5726 }
5728 /* Handle the case of comparisons with constants. If there is something in
5729 common between the masks, those bits of the constants must be the same.
5730 If not, the condition is always false. Test for this to avoid generating
5731 incorrect code below. */
5736 {
5738 {
5741 }
5742 else
5743 {
5746 }
5747 }
5749 /* Construct the expression we will return. First get the component
5750 reference we will make. Unless the mask is all ones the width of
5751 that field, perform the mask operation. Then compare with the
5752 merged constant. */
5762 }
5763 \f
5764 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5765 constant. */
5767 static tree
5770 {
5773 tree comp_const;
5774 tree minmax_const;
5776 tree inner;
5787 /* If something does not permit us to optimize, return the original tree. */
5795 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5796 and GT_EXPR, doing the rest with recursive calls using logical
5797 simplifications. */
5799 {
5801 {
5802 tree tem
5809 }
5812 return
5814 optimize_minmax_comparison
5816 optimize_minmax_comparison
5821 /* MAX (X, 0) == 0 -> X <= 0 */
5825 /* MAX (X, 0) == 5 -> X == 5 */
5829 /* MAX (X, 0) == -1 -> false */
5833 /* MIN (X, 0) == 0 -> X >= 0 */
5837 /* MIN (X, 0) == 5 -> false */
5840 else
5841 /* MIN (X, 0) == -1 -> X == -1 */
5846 /* MAX (X, 0) > 0 -> X > 0
5847 MAX (X, 0) > 5 -> X > 5 */
5851 /* MAX (X, 0) > -1 -> true */
5855 /* MIN (X, 0) > 0 -> false
5856 MIN (X, 0) > 5 -> false */
5859 else
5860 /* MIN (X, 0) > -1 -> X > -1 */
5865 }
5866 }
5867 \f
5868 /* T is an integer expression that is being multiplied, divided, or taken a
5869 modulus (CODE says which and what kind of divide or modulus) by a
5870 constant C. See if we can eliminate that operation by folding it with
5871 other operations already in T. WIDE_TYPE, if non-null, is a type that
5872 should be used for the computation if wider than our type.
5874 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5875 (X * 2) + (Y * 4). We must, however, be assured that either the original
5876 expression would not overflow or that overflow is undefined for the type
5877 in the language in question.
5879 If we return a non-null expression, it is an equivalent form of the
5880 original computation, but need not be in the original type.
5882 We set *STRICT_OVERFLOW_P to true if the return values depends on
5883 signed overflow being undefined. Otherwise we do not change
5884 *STRICT_OVERFLOW_P. */
5886 static tree
5889 {
5890 /* To avoid exponential search depth, refuse to allow recursion past
5891 three levels. Beyond that (1) it's highly unlikely that we'll find
5892 something interesting and (2) we've probably processed it before
5893 when we built the inner expression. */
5896 tree ret;
5901 depth++;
5903 depth--;
5906 }
5908 static tree
5911 {
5922 /* Don't deal with constants of zero here; they confuse the code below. */
5932 /* Note that we need not handle conditional operations here since fold
5933 already handles those cases. So just do arithmetic here. */
5935 {
5937 /* For a constant, we can always simplify if we are a multiply
5938 or (for divide and modulus) if it is a multiple of our constant. */
5946 /* If op0 is an expression ... */
5952 /* ... and has wrapping overflow, and its type is smaller
5953 than ctype, then we cannot pass through as widening. */
5957 /* ... or this is a truncation (t is narrower than op0),
5958 then we cannot pass through this narrowing. */
5961 /* ... or signedness changes for division or modulus,
5962 then we cannot pass through this conversion. */
5966 /* ... or has undefined overflow while the converted to
5967 type has not, we cannot do the operation in the inner type
5968 as that would introduce undefined overflow. */
5973 /* Pass the constant down and see if we can make a simplification. If
5974 we can, replace this expression with the inner simplification for
5975 possible later conversion to our or some other type. */
5980 code == MULT_EXPR
5982 strict_overflow_p))))
5987 /* If widening the type changes it from signed to unsigned, then we
5988 must avoid building ABS_EXPR itself as unsigned. */
5990 {
5994 {
5997 }
5999 }
6000 /* If the constant is negative, we cannot simplify this. */
6003 /* FALLTHROUGH */
6005 /* For division and modulus, type can't be unsigned, as e.g.
6006 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6007 For signed types, even with wrapping overflow, this is fine. */
6016 /* If widening the type changes the signedness, then we can't perform
6017 this optimization as that changes the result. */
6021 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6027 {
6034 }
6038 /* If the second operand is constant, this is a multiplication
6039 or floor division, by a power of two, so we can treat it that
6040 way unless the multiplier or divisor overflows. Signed
6041 left-shift overflow is implementation-defined rather than
6042 undefined in C90, so do not convert signed left shift into
6043 multiplication. */
6046 /* const_binop may not detect overflow correctly,
6047 so check for it explicitly here. */
6051 size_one_node,
6052 op1)))
6056 ctype,
6058 t1),
6063 /* See if we can eliminate the operation on both sides. If we can, we
6064 can return a new PLUS or MINUS. If we can't, the only remaining
6065 cases where we can do anything are if the second operand is a
6066 constant. */
6072 /* If not multiplication, we can only do this if both operands
6073 are divisible by c. */
6076 {
6081 }
6083 /* If this was a subtraction, negate OP1 and set it to be an addition.
6084 This simplifies the logic below. */
6086 {
6088 /* If OP1 was not easily negatable, the constant may be OP0. */
6090 {
6097 }
6098 }
6103 /* If either OP1 or C are negative, this optimization is not safe for
6104 some of the division and remainder types while for others we need
6105 to change the code. */
6107 {
6115 }
6117 /* If it's a multiply or a division/modulus operation of a multiple
6118 of our constant, do the operation and verify it doesn't overflow. */
6121 {
6124 /* We allow the constant to overflow with wrapping semantics. */
6128 }
6129 else
6132 /* If we have an unsigned type, we cannot widen the operation since it
6133 will change the result if the original computation overflowed. */
6137 /* If we were able to eliminate our operation from the first side,
6138 apply our operation to the second side and reform the PLUS. */
6142 /* The last case is if we are a multiply. In that case, we can
6143 apply the distributive law to commute the multiply and addition
6144 if the multiplication of the constants doesn't overflow
6145 and overflow is defined. With undefined overflow
6146 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6152 op1);
6157 /* We have a special case here if we are doing something like
6158 (C * 8) % 4 since we know that's zero. */
6161 /* If the multiplication can overflow we cannot optimize this. */
6165 {
6168 }
6170 /* ... fall through ... */
6174 /* If we can extract our operation from the LHS, do so and return a
6175 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6176 do something only if the second operand is a constant. */
6190 /* If these are the same operation types, we can associate them
6191 assuming no overflow. */
6193 {
6205 }
6207 /* If these operations "cancel" each other, we have the main
6208 optimizations of this pass, which occur when either constant is a
6209 multiple of the other, in which case we replace this with either an
6210 operation or CODE or TCODE.
6212 If we have an unsigned type, we cannot do this since it will change
6213 the result if the original computation overflowed. */
6220 {
6222 {
6229 }
6231 {
6238 }
6239 }
6244 }
6247 }
6248 \f
6249 /* Return a node which has the indicated constant VALUE (either 0 or
6250 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6251 and is of the indicated TYPE. */
6253 tree
6255 {
6264 else
6266 }
6269 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6270 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6271 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6272 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6273 COND is the first argument to CODE; otherwise (as in the example
6274 given here), it is the second argument. TYPE is the type of the
6275 original expression. Return NULL_TREE if no simplification is
6276 possible. */
6278 static tree
6283 {
6293 {
6297 /* If this operand throws an expression, then it does not make
6298 sense to try to perform a logical or arithmetic operation
6299 involving it. */
6304 }
6305 else
6306 {
6311 }
6316 /* This transformation is only worthwhile if we don't have to wrap ARG
6317 in a SAVE_EXPR and the operation can be simplified without recursing
6318 on at least one of the branches once its pushed inside the COND_EXPR. */
6327 {
6331 else
6333 }
6335 {
6339 else
6341 }
6343 /* Check that we have simplified at least one of the branches. */
6348 }
6350 \f
6351 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6353 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6354 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6355 ADDEND is the same as X.
6357 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6358 and finite. The problematic cases are when X is zero, and its mode
6359 has signed zeros. In the case of rounding towards -infinity,
6360 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6361 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6363 bool
6365 {
6369 /* Don't allow the fold with -fsignaling-nans. */
6373 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6377 /* In a vector or complex, we would need to check the sign of all zeros. */
6381 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6385 /* The mode has signed zeros, and we have to honor their sign.
6386 In this situation, there is only one case we can return true for.
6387 X - 0 is the same as X unless rounding towards -infinity is
6388 supported. */
6390 }
6392 /* Subroutine of fold() that checks comparisons of built-in math
6393 functions against real constants.
6395 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6396 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6397 is the type of the result and ARG0 and ARG1 are the operands of the
6398 comparison. ARG1 must be a TREE_REAL_CST.
6400 The function returns the constant folded tree if a simplification
6401 can be made, and NULL_TREE otherwise. */
6403 static tree
6407 {
6408 REAL_VALUE_TYPE c;
6411 {
6417 {
6418 /* sqrt(x) < y is always false, if y is negative. */
6422 /* sqrt(x) > y is always true, if y is negative and we
6423 don't care about NaNs, i.e. negative values of x. */
6427 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6430 }
6432 {
6433 REAL_VALUE_TYPE c2;
6439 {
6440 /* sqrt(x) > y is x == +Inf, when y is very large. */
6445 /* sqrt(x) > y is always false, when y is very large
6446 and we don't care about infinities. */
6448 }
6450 /* sqrt(x) > c is the same as x > c*c. */
6453 }
6455 {
6456 REAL_VALUE_TYPE c2;
6462 {
6463 /* sqrt(x) < y is always true, when y is a very large
6464 value and we don't care about NaNs or Infinities. */
6468 /* sqrt(x) < y is x != +Inf when y is very large and we
6469 don't care about NaNs. */
6474 /* sqrt(x) < y is x >= 0 when y is very large and we
6475 don't care about Infinities. */
6480 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6485 dconst0)),
6488 c2)));
6489 }
6491 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6496 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6501 dconst0)),
6504 c2)));
6505 }
6506 }
6509 }
6511 /* Subroutine of fold() that optimizes comparisons against Infinities,
6512 either +Inf or -Inf.
6514 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6515 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6516 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6518 The function returns the constant folded tree if a simplification
6519 can be made, and NULL_TREE otherwise. */
6521 static tree
6524 {
6525 machine_mode mode;
6526 REAL_VALUE_TYPE max;
6527 tree temp;
6532 /* For negative infinity swap the sense of the comparison. */
6538 {
6540 /* x > +Inf is always false, if with ignore sNANs. */
6546 /* x <= +Inf is always true, if we don't case about NaNs. */
6550 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6556 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6562 /* x < +Inf is always equal to x <= DBL_MAX. */
6568 /* x != +Inf is always equal to !(x > DBL_MAX). */
6580 }
6583 }
6585 /* Subroutine of fold() that optimizes comparisons of a division by
6586 a nonzero integer constant against an integer constant, i.e.
6587 X/C1 op C2.
6589 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6590 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6591 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6593 The function returns the constant folded tree if a simplification
6594 can be made, and NULL_TREE otherwise. */
6596 static tree
6599 {
6607 /* We have to do this the hard way to detect unsigned overflow.
6608 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6614 {
6619 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6623 }
6625 {
6629 {
6648 }
6649 }
6650 else
6651 {
6652 /* A negative divisor reverses the relational operators. */
6658 {
6677 }
6678 }
6681 {
6702 {
6705 }
6710 {
6713 }
6718 {
6721 }
6726 {
6729 }
6734 }
6737 }
6740 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6741 equality/inequality test, then return a simplified form of the test
6742 using a sign testing. Otherwise return NULL. TYPE is the desired
6743 result type. */
6745 static tree
6748 tree result_type)
6749 {
6750 /* If this is testing a single bit, we can optimize the test. */
6754 {
6755 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6756 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6760 /* This is only a win if casting to a signed type is cheap,
6761 i.e. when arg00's type is not a partial mode. */
6764 {
6767 result_type,
6770 }
6771 }
6774 }
6776 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6777 equality/inequality test, then return a simplified form of
6778 the test using shifts and logical operations. Otherwise return
6779 NULL. TYPE is the desired result type. */
6781 tree
6784 {
6785 /* If this is testing a single bit, we can optimize the test. */
6789 {
6798 /* First, see if we can fold the single bit test into a sign-bit
6799 test. */
6801 result_type);
6805 /* Otherwise we have (A & C) != 0 where C is a single bit,
6806 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6807 Similarly for (A & C) == 0. */
6809 /* If INNER is a right shift of a constant and it plus BITNUM does
6810 not overflow, adjust BITNUM and INNER. */
6816 {
6819 }
6821 /* If we are going to be able to omit the AND below, we must do our
6822 operations as unsigned. If we must use the AND, we have a choice.
6823 Normally unsigned is faster, but for some machines signed is. */
6824 #ifdef LOAD_EXTEND_OP
6827 #else
6829 #endif
6845 /* Put the AND last so it can combine with more things. */
6848 /* Make sure to return the proper type. */
6852 }
6854 }
6856 /* Check whether we are allowed to reorder operands arg0 and arg1,
6857 such that the evaluation of arg1 occurs before arg0. */
6859 static bool
6861 {
6868 }
6870 /* Test whether it is preferable two swap two operands, ARG0 and
6871 ARG1, for example because ARG0 is an integer constant and ARG1
6872 isn't. If REORDER is true, only recommend swapping if we can
6873 evaluate the operands in reverse order. */
6875 bool
6877 {
6895 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6896 for commutative and comparison operators. Ensuring a canonical
6897 form allows the optimizers to find additional redundancies without
6898 having to explicitly check for both orderings. */
6904 /* Put SSA_NAMEs last. */
6910 /* Put variables last. */
6917 }
6919 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6920 ARG0 is extended to a wider type. */
6922 static tree
6925 {
6927 tree arg1_unw;
6936 #ifdef HAVE_canonicalize_funcptr_for_compare
6937 /* Disable this optimization if we're casting a function pointer
6938 type on targets that require function pointer canonicalization. */
6943 #endif
6950 /* If possible, express the comparison in the shorter mode. */
6970 /* If we are comparing with the integer that does not fit into the range
6971 of the shorter type, the result is known. */
6982 {
7009 }
7012 }
7014 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7015 ARG0 just the signedness is changed. */
7017 static tree
7020 {
7021 tree arg0_inner;
7031 #ifdef HAVE_canonicalize_funcptr_for_compare
7032 /* Disable this optimization if we're casting a function pointer
7033 type on targets that require function pointer canonicalization. */
7038 #endif
7059 else
7063 }
7066 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7067 means A >= Y && A != MAX, but in this case we know that
7068 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7070 static tree
7072 {
7079 else
7088 {
7091 }
7093 {
7096 }
7097 else
7104 {
7105 /* Convert the pointer types into integer before taking the difference. */
7109 }
7110 else
7117 }
7119 /* Fold a sum or difference of at least one multiplication.
7120 Returns the folded tree or NULL if no simplification could be made. */
7122 static tree
7125 {
7129 /* (A * C) +- (B * C) -> (A+-B) * C.
7130 (A * C) +- A -> A * (C+-1).
7131 We are most concerned about the case where C is a constant,
7132 but other combinations show up during loop reduction. Since
7133 it is not difficult, try all four possibilities. */
7136 {
7139 }
7141 {
7144 }
7145 else
7146 {
7147 /* We cannot generate constant 1 for fract. */
7152 }
7154 {
7157 }
7159 {
7161 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7162 the purpose of this canonicalization. */
7166 {
7169 }
7170 else
7172 }
7173 else
7174 {
7175 /* We cannot generate constant 1 for fract. */
7180 }
7192 /* No identical multiplicands; see if we can find a common
7193 power-of-two factor in non-power-of-two multiplies. This
7194 can help in multi-dimensional array access. */
7197 {
7200 tree maybe_same;
7204 /* Move min of absolute values to int11. */
7206 {
7211 }
7212 else
7216 /* The remainder should not be a constant, otherwise we
7217 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7218 increased the number of multiplications necessary. */
7220 {
7228 }
7229 }
7239 }
7241 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7242 specified by EXPR into the buffer PTR of length LEN bytes.
7243 Return the number of bytes placed in the buffer, or zero
7244 upon failure. */
7246 static int
7248 {
7262 {
7264 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7265 number of bytes. */
7269 {
7276 else
7278 }
7279 else
7284 }
7286 }
7289 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7290 specified by EXPR into the buffer PTR of length LEN bytes.
7291 Return the number of bytes placed in the buffer, or zero
7292 upon failure. */
7294 static int
7296 {
7300 FIXED_VALUE_TYPE value;
7316 }
7319 /* Subroutine of native_encode_expr. Encode the REAL_CST
7320 specified by EXPR into the buffer PTR of length LEN bytes.
7321 Return the number of bytes placed in the buffer, or zero
7322 upon failure. */
7324 static int
7326 {
7332 /* There are always 32 bits in each long, no matter the size of
7333 the hosts long. We handle floating point representations with
7334 up to 192 bits. */
7348 {
7353 {
7360 else
7362 }
7363 else
7369 }
7371 }
7373 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7374 specified by EXPR into the buffer PTR of length LEN bytes.
7375 Return the number of bytes placed in the buffer, or zero
7376 upon failure. */
7378 static int
7380 {
7382 tree part;
7397 }
7400 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7401 specified by EXPR into the buffer PTR of length LEN bytes.
7402 Return the number of bytes placed in the buffer, or zero
7403 upon failure. */
7405 static int
7407 {
7417 {
7419 {
7422 }
7433 }
7435 }
7438 /* Subroutine of native_encode_expr. Encode the STRING_CST
7439 specified by EXPR into the buffer PTR of length LEN bytes.
7440 Return the number of bytes placed in the buffer, or zero
7441 upon failure. */
7443 static int
7445 {
7447 HOST_WIDE_INT total_bytes;
7461 {
7464 {
7467 }
7470 }
7471 else
7474 }
7477 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7478 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7479 buffer PTR of length LEN bytes. If OFF is not -1 then start
7480 the encoding at byte offset OFF and encode at most LEN bytes.
7481 Return the number of bytes placed in the buffer, or zero upon failure. */
7483 int
7485 {
7487 {
7508 }
7509 }
7512 /* Subroutine of native_interpret_expr. Interpret the contents of
7513 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7514 If the buffer cannot be interpreted, return NULL_TREE. */
7516 static tree
7518 {
7528 }
7531 /* Subroutine of native_interpret_expr. Interpret the contents of
7532 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7533 If the buffer cannot be interpreted, return NULL_TREE. */
7535 static tree
7537 {
7539 double_int result;
7540 FIXED_VALUE_TYPE fixed_value;
7550 }
7553 /* Subroutine of native_interpret_expr. Interpret the contents of
7554 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7555 If the buffer cannot be interpreted, return NULL_TREE. */
7557 static tree
7559 {
7564 /* There are always 32 bits in each long, no matter the size of
7565 the hosts long. We handle floating point representations with
7566 up to 192 bits. */
7567 REAL_VALUE_TYPE r;
7578 {
7581 {
7588 else
7590 }
7591 else
7596 }
7600 }
7603 /* Subroutine of native_interpret_expr. Interpret the contents of
7604 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7605 If the buffer cannot be interpreted, return NULL_TREE. */
7607 static tree
7609 {
7624 }
7627 /* Subroutine of native_interpret_expr. Interpret the contents of
7628 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7629 If the buffer cannot be interpreted, return NULL_TREE. */
7631 static tree
7633 {
7646 {
7651 }
7653 }
7656 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7657 the buffer PTR of length LEN as a constant of type TYPE. For
7658 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7659 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7660 return NULL_TREE. */
7662 tree
7664 {
7666 {
7688 }
7689 }
7691 /* Returns true if we can interpret the contents of a native encoding
7692 as TYPE. */
7694 static bool
7696 {
7698 {
7711 }
7712 }
7714 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7715 TYPE at compile-time. If we're unable to perform the conversion
7716 return NULL_TREE. */
7718 static tree
7720 {
7721 /* We support up to 512-bit values (for V8DFmode). */
7725 /* Check that the host and target are sane. */
7734 }
7736 /* Build an expression for the address of T. Folds away INDIRECT_REF
7737 to avoid confusing the gimplify process. */
7739 tree
7741 {
7742 /* The size of the object is not relevant when talking about its address. */
7747 {
7752 }
7762 {
7767 }
7768 else
7772 }
7774 /* Build an expression for the address of T. */
7776 tree
7778 {
7782 }
7784 /* Fold a unary expression of code CODE and type TYPE with operand
7785 OP0. Return the folded expression if folding is successful.
7786 Otherwise, return NULL_TREE. */
7788 tree
7790 {
7791 tree tem;
7792 tree arg0;
7800 {
7803 {
7804 /* Don't use STRIP_NOPS, because signedness of argument type
7805 matters. */
7807 }
7808 else
7809 {
7810 /* Strip any conversions that don't change the mode. This
7811 is safe for every expression, except for a comparison
7812 expression because its signedness is derived from its
7813 operands.
7815 Note that this is done as an internal manipulation within
7816 the constant folder, in order to find the simplest
7817 representation of the arguments so that their form can be
7818 studied. In any cases, the appropriate type conversions
7819 should be put back in the tree that will get out of the
7820 constant folder. */
7822 }
7825 {
7828 {
7832 }
7833 }
7834 }
7841 {
7848 {
7862 /* If this was a conversion, and all we did was to move into
7863 inside the COND_EXPR, bring it back out. But leave it if
7864 it is a conversion from integer to integer and the
7865 result precision is no wider than a word since such a
7866 conversion is cheap and may be optimized away by combine,
7867 while it couldn't if it were outside the COND_EXPR. Then return
7868 so we don't get into an infinite recursion loop taking the
7869 conversion out and then back in. */
7881 && (INTEGRAL_TYPE_P
7894 }
7895 }
7898 {
7904 CASE_CONVERT:
7908 {
7909 /* If we have (type) (a CMP b) and type is an integral type, return
7910 new expression involving the new type. Canonicalize
7911 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7912 non-integral type.
7913 Do not fold the result as that would not simplify further, also
7914 folding again results in recursions. */
7924 }
7926 /* Handle (T *)&A.B.C for A being of type T and B and C
7927 living at offset zero. This occurs frequently in
7928 C++ upcasting and then accessing the base. */
7932 {
7934 tree offset;
7935 machine_mode mode;
7940 /* If the reference was to a (constant) zero offset, we can use
7941 the address of the base if it has the same base type
7942 as the result type and the pointer type is unqualified. */
7949 }
7953 /* Detect assigning a bitfield. */
7955 && DECL_BIT_FIELD
7957 {
7958 /* Don't leave an assignment inside a conversion
7959 unless assigning a bitfield. */
7961 /* First do the assignment, then return converted constant. */
7966 }
7968 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7969 constants (if x has signed type, the sign bit cannot be set
7970 in c). This folds extension into the BIT_AND_EXPR.
7971 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7972 very likely don't have maximal range for their precision and this
7973 transformation effectively doesn't preserve non-maximal ranges. */
7977 {
7988 <= HOST_BITS_PER_WIDE_INT
7990 {
7994 cst &= HOST_WIDE_INT_M1U
7997 #ifdef LOAD_EXTEND_OP
7999 && !flag_syntax_only
8002 {
8006 }
8007 #endif
8008 }
8010 {
8015 }
8016 }
8018 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8019 when one of the new casts will fold away. Conservatively we assume
8020 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8027 {
8031 return fold_build_pointer_plus_loc
8033 }
8035 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8036 of the same precision, and X is an integer type not narrower than
8037 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8043 {
8049 }
8051 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8052 type of X and Y (integer types only). */
8057 {
8058 /* Be careful not to introduce new overflows. */
8059 tree mult_type;
8062 else
8066 {
8073 }
8074 }
8092 /* Convert fabs((double)float) into (double)fabsf(float). */
8095 {
8101 targ0));
8102 }
8103 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8107 /* Strip sign ops from argument. */
8109 {
8114 }
8121 {
8127 }
8133 /* Convert ~ (-A) to A - 1. */
8138 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8144 {
8145 /* Perform the negation in ARG0's type and only then convert
8146 to TYPE as to avoid introducing undefined behavior. */
8151 }
8152 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8171 /* Note that the operand of this must be an int
8172 and its values must be 0 or 1.
8173 ("true" is a fixed value perhaps depending on the language,
8174 but we don't handle values other than 1 correctly yet.) */
8184 {
8192 }
8194 {
8199 }
8201 {
8205 {
8214 }
8215 }
8222 {
8230 }
8232 {
8236 }
8238 {
8242 {
8251 }
8252 }
8256 /* Fold *&X to X if X is an lvalue. */
8258 {
8265 }
8271 }
8274 /* If the operation was a conversion do _not_ mark a resulting constant
8275 with TREE_OVERFLOW if the original constant was not. These conversions
8276 have implementation defined behavior and retaining the TREE_OVERFLOW
8277 flag here would confuse later passes such as VRP. */
8278 tree
8281 {
8290 }
8292 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8293 operands OP0 and OP1. LOC is the location of the resulting expression.
8294 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8295 Return the folded expression if folding is successful. Otherwise,
8296 return NULL_TREE. */
8297 static tree
8300 {
8301 tree tem;
8303 /* We only do these simplifications if we are optimizing. */
8307 /* Check for things like (A || B) && (A || C). We can convert this
8308 to A || (B && C). Note that either operator can be any of the four
8309 truth and/or operations and the transformation will still be
8310 valid. Also note that we only care about order for the
8311 ANDIF and ORIF operators. If B contains side effects, this
8312 might change the truth-value of A. */
8319 {
8339 /* This case if tricky because we must either have commutative
8340 operators or else A10 must not have side-effects. */
8346 a01);
8347 }
8349 /* See if we can build a range comparison. */
8355 {
8359 }
8363 {
8367 }
8369 /* Check for the possibility of merging component references. If our
8370 lhs is another similar operation, try to merge its rhs with our
8371 rhs. Then try to merge our lhs and rhs. */
8385 {
8392 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8393 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8394 We don't want to pack more than two leafs to a non-IF AND/OR
8395 expression.
8396 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8397 equal to IF-CODE, then we don't want to add right-hand operand.
8398 If the inner right-hand side of left-hand operand has
8399 side-effects, or isn't simple, then we can't add to it,
8400 as otherwise we might destroy if-sequence. */
8403 /* Needed for sequence points to handle trappings, and
8404 side-effects. */
8406 {
8408 arg1);
8410 tem);
8411 }
8412 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8413 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8416 /* Needed for sequence points to handle trappings, and
8417 side-effects. */
8419 {
8424 }
8425 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8426 into (A OR B).
8427 For sequence point consistancy, we need to check for trapping,
8428 and side-effects. */
8432 }
8435 }
8437 /* Fold a binary expression of code CODE and type TYPE with operands
8438 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8439 Return the folded expression if folding is successful. Otherwise,
8440 return NULL_TREE. */
8442 static tree
8444 {
8451 else
8454 /* MIN (MAX (a, b), b) == b. */
8459 /* MIN (MAX (b, a), b) == b. */
8465 /* MIN (a, MAX (a, b)) == a. */
8471 /* MIN (a, MAX (b, a)) == a. */
8478 }
8480 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8481 by changing CODE to reduce the magnitude of constants involved in
8482 ARG0 of the comparison.
8483 Returns a canonicalized comparison tree if a simplification was
8484 possible, otherwise returns NULL_TREE.
8485 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8486 valid if signed overflow is undefined. */
8488 static tree
8492 {
8498 /* Match A +- CST code arg1 and CST code arg1. We can change the
8499 first form only if overflow is undefined. */
8501 /* In principle pointers also have undefined overflow behavior,
8502 but that causes problems elsewhere. */
8510 /* Identify the constant in arg0 and its sign. */
8513 else
8517 /* Overflowed constants and zero will cause problems. */
8522 /* See if we can reduce the magnitude of the constant in
8523 arg0 by changing the comparison code. */
8525 {
8526 /* CST <= arg1 -> CST-1 < arg1. */
8529 /* -CST < arg1 -> -CST-1 <= arg1. */
8532 /* CST > arg1 -> CST-1 >= arg1. */
8535 /* -CST >= arg1 -> -CST-1 > arg1. */
8538 else
8540 /* arg1 code' CST' might be more canonical. */
8542 }
8543 else
8544 {
8545 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8549 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8553 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8557 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8561 else
8564 }
8566 /* Now build the constant reduced in magnitude. But not if that
8567 would produce one outside of its types range. */
8575 /* We cannot swap the comparison here as that would cause us to
8576 endlessly recurse. */
8585 /* If swapping might yield to a more canonical form, do so. */
8588 else
8590 }
8592 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8593 overflow further. Try to decrease the magnitude of constants involved
8594 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8595 and put sole constants at the second argument position.
8596 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8598 static tree
8601 {
8602 tree t;
8607 /* Try canonicalization by simplifying arg0. */
8612 {
8616 }
8618 /* Try canonicalization by simplifying arg1 using the swapped
8619 comparison. */
8627 }
8629 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8630 space. This is used to avoid issuing overflow warnings for
8631 expressions like &p->x which can not wrap. */
8633 static bool
8635 {
8642 wide_int wi_offset;
8648 else
8664 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8665 array. */
8667 {
8668 HOST_WIDE_INT base_size;
8673 }
8676 }
8678 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8679 kind INTEGER_CST. This makes sure to properly sign-extend the
8680 constant. */
8682 static HOST_WIDE_INT
8684 {
8690 }
8692 /* Subroutine of fold_binary. This routine performs all of the
8693 transformations that are common to the equality/inequality
8694 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8695 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8696 fold_binary should call fold_binary. Fold a comparison with
8697 tree code CODE and type TYPE with operands OP0 and OP1. Return
8698 the folded comparison or NULL_TREE. */
8700 static tree
8703 {
8713 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8720 {
8721 const enum tree_code
8728 /* If the constant operation overflowed this can be
8729 simplified as a comparison against INT_MAX/INT_MIN. */
8732 {
8736 /* Get the sign of the constant on the lhs if the
8737 operation were VARIABLE + CONST1. */
8741 /* The sign of the constant determines if we overflowed
8742 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8743 Canonicalize to the INT_MIN overflow by swapping the comparison
8744 if necessary. */
8748 /* We now can look at the canonicalized case
8749 VARIABLE + 1 CODE2 INT_MIN
8750 and decide on the result. */
8752 {
8756 return
8762 return
8767 }
8768 }
8769 else
8770 {
8773 "when changing X +- C1 cmp C2 to "
8775 WARN_STRICT_OVERFLOW_COMPARISON);
8777 }
8778 }
8780 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8782 && equality_code
8784 {
8785 /* ??? The transformation is valid for the other operators if overflow
8786 is undefined for the type, but performing it here badly interacts
8787 with the transformation in fold_cond_expr_with_comparison which
8788 attempts to synthetize ABS_EXPR. */
8792 WARN_STRICT_OVERFLOW_COMPARISON);
8795 }
8797 /* For comparisons of pointers we can decompose it to a compile time
8798 comparison of the base objects and the offsets into the object.
8799 This requires at least one operand being an ADDR_EXPR or a
8800 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8806 {
8809 machine_mode mode;
8813 /* Get base and offset for the access. Strip ADDR_EXPR for
8814 get_inner_reference, but put it back by stripping INDIRECT_REF
8815 off the base object if possible. indirect_baseN will be true
8816 if baseN is not an address but refers to the object itself. */
8819 {
8825 else
8827 }
8829 {
8833 {
8836 }
8839 {
8844 {
8847 }
8848 }
8849 }
8853 {
8859 else
8861 }
8863 {
8867 {
8870 }
8873 {
8878 {
8881 }
8882 }
8883 }
8885 /* A local variable can never be pointed to by
8886 the default SSA name of an incoming parameter. */
8888 && indirect_base0
8891 && !indirect_base1
8896 && indirect_base1
8899 && !indirect_base0
8903 {
8908 }
8909 /* If we have equivalent bases we might be able to simplify. */
8912 {
8913 /* We can fold this expression to a constant if the non-constant
8914 offset parts are equal. */
8923 {
8929 "occur when comparing P +- C1 with "
8931 WARN_STRICT_OVERFLOW_CONDITIONAL);
8934 {
8948 }
8949 }
8950 /* We can simplify the comparison to a comparison of the variable
8951 offset parts if the constant offset parts are equal.
8952 Be careful to use signed sizetype here because otherwise we
8953 mess with array offsets in the wrong way. This is possible
8954 because pointer arithmetic is restricted to retain within an
8955 object and overflow on pointer differences is undefined as of
8956 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8958 && (equality_code
8961 {
8962 /* By converting to signed sizetype we cover middle-end pointer
8963 arithmetic which operates on unsigned pointer types of size
8964 type size and ARRAY_REF offsets which are properly sign or
8965 zero extended from their type in case it is narrower than
8966 sizetype. */
8969 else
8973 else
8980 "occur when comparing P +- C1 with "
8982 WARN_STRICT_OVERFLOW_COMPARISON);
8985 }
8986 }
8987 /* For non-equal bases we can simplify if they are addresses
8988 declarations with different addresses. */
8990 /* We know that !operand_equal_p (base0, base1, 0)
8991 because the if condition was false. But make
8992 sure two decls are not the same. */
8998 /* Watch for aliases. */
9003 {
9010 }
9011 /* For equal offsets we can simplify to a comparison of the
9012 base addresses. */
9014 && (indirect_base0
9016 && (indirect_base1
9021 {
9027 }
9028 }
9030 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9031 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9032 the resulting offset is smaller in absolute value than the
9033 original one and has the same sign. */
9041 {
9046 tree cst;
9048 "occur when combining constants around "
9051 /* Put the constant on the side where it doesn't overflow and is
9052 of lower absolute value and of same sign than before. */
9059 {
9062 variable1,
9066 }
9074 {
9080 variable2);
9081 }
9082 }
9084 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9085 signed arithmetic case. That form is created by the compiler
9086 often enough for folding it to be of value. One example is in
9087 computing loop trip counts after Operator Strength Reduction. */
9093 {
9099 /* Handle unfolded multiplication by zero. */
9104 "eliminating multiplication in comparison "
9106 WARN_STRICT_OVERFLOW_COMPARISON);
9108 /* If const1 is negative we swap the sense of the comparison. */
9113 }
9120 {
9128 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9134 /* (-a) CMP (-b) -> b CMP a */
9141 {
9142 REAL_VALUE_TYPE cst;
9145 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9152 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9153 /* a CMP (-0) -> a CMP 0 */
9158 /* x != NaN is always true, other ops are always false. */
9161 {
9164 }
9166 /* Fold comparisons against infinity. */
9169 {
9173 }
9174 }
9176 /* If this is a comparison of a real constant with a PLUS_EXPR
9177 or a MINUS_EXPR of a real constant, we can convert it into a
9178 comparison with a revised real constant as long as no overflow
9179 occurs when unsafe_math_optimizations are enabled. */
9191 /* Likewise, we can simplify a comparison of a real constant with
9192 a MINUS_EXPR whose first operand is also a real constant, i.e.
9193 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9194 floating-point types only if -fassociative-math is set. */
9200 arg1))
9205 /* Fold comparisons against built-in math functions. */
9207 && flag_unsafe_math_optimizations
9209 {
9213 {
9217 }
9218 }
9219 }
9223 {
9224 /* If we are widening one operand of an integer comparison,
9225 see if the other operand is similarly being widened. Perhaps we
9226 can do the comparison in the narrower type. */
9231 /* Or if we are changing signedness. */
9235 }
9237 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9238 constant, we can simplify it. */
9243 {
9247 }
9249 /* Simplify comparison of something with itself. (For IEEE
9250 floating-point, we can only do some of these simplifications.) */
9252 {
9254 {
9269 /* For NE, we can only do this simplification if integer
9270 or we don't honor IEEE floating point NaNs. */
9274 /* ... fall through ... */
9280 }
9281 }
9283 /* If we are comparing an expression that just has comparisons
9284 of two integer values, arithmetic expressions of those comparisons,
9285 and constants, we can simplify it. There are only three cases
9286 to check: the two values can either be equal, the first can be
9287 greater, or the second can be greater. Fold the expression for
9288 those three values. Since each value must be 0 or 1, we have
9289 eight possibilities, each of which corresponds to the constant 0
9290 or 1 or one of the six possible comparisons.
9292 This handles common cases like (a > b) == 0 but also handles
9293 expressions like ((x > y) - (y > x)) > 0, which supposedly
9294 occur in macroized code. */
9297 {
9302 /* Don't handle degenerate cases here; they should already
9303 have been handled anyway. */
9312 {
9316 /* We can't just pass T to eval_subst in case cval1 or cval2
9317 was the same as ARG1. */
9319 tree high_result
9323 arg1);
9324 tree equal_result
9328 arg1);
9329 tree low_result
9333 arg1);
9335 /* All three of these results should be 0 or 1. Confirm they are.
9336 Then use those values to select the proper code to use. */
9341 {
9342 /* Make a 3-bit mask with the high-order bit being the
9343 value for `>', the next for '=', and the low for '<'. */
9347 {
9349 /* Always false. */
9370 /* Always true. */
9372 }
9375 {
9379 }
9381 }
9382 }
9383 }
9385 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9386 into a single range test. */
9394 {
9398 }
9400 /* Fold ~X op ~Y as Y op X. */
9403 {
9409 }
9411 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9414 {
9420 }
9423 }
9426 /* Subroutine of fold_binary. Optimize complex multiplications of the
9427 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9428 argument EXPR represents the expression "z" of type TYPE. */
9430 static tree
9432 {
9437 {
9440 }
9442 {
9445 }
9446 else
9447 {
9451 }
9460 }
9463 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9464 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9465 guarantees that P and N have the same least significant log2(M) bits.
9466 N is not otherwise constrained. In particular, N is not normalized to
9467 0 <= N < M as is common. In general, the precise value of P is unknown.
9468 M is chosen as large as possible such that constant N can be determined.
9470 Returns M and sets *RESIDUE to N.
9472 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9473 account. This is not always possible due to PR 35705.
9474 */
9476 static unsigned HOST_WIDE_INT
9479 {
9486 {
9491 }
9493 {
9501 allow_func_align);
9507 {
9510 }
9512 {
9515 {
9518 /* Compute the greatest power-of-2 divisor of op1. */
9522 /* If align is non-zero and less than *modulus, replace
9523 *modulus with align., If align is 0, then either op1 is 0
9524 or the greatest power-of-2 divisor of op1 doesn't fit in an
9525 unsigned HOST_WIDE_INT. In either case, no additional
9526 constraint is imposed. */
9531 }
9532 }
9533 }
9535 /* If we get here, we were unable to determine anything useful about the
9536 expression. */
9538 }
9540 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9541 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9543 static bool
9545 {
9549 {
9552 }
9554 {
9560 else
9562 }
9563 else
9569 }
9571 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9572 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9573 NULL_TREE otherwise. */
9575 static tree
9577 {
9594 {
9598 }
9601 {
9607 }
9608 else
9610 }
9612 /* Try to fold a pointer difference of type TYPE two address expressions of
9613 array references AREF0 and AREF1 using location LOC. Return a
9614 simplified expression for the difference or NULL_TREE. */
9616 static tree
9619 {
9624 /* If the bases are array references as well, recurse. If the bases
9625 are pointer indirections compute the difference of the pointers.
9626 If the bases are equal, we are set. */
9629 && (base_offset
9637 {
9643 base_offset,
9646 }
9648 }
9650 /* If the real or vector real constant CST of type TYPE has an exact
9651 inverse, return it, else return NULL. */
9653 tree
9655 {
9656 REAL_VALUE_TYPE r;
9658 machine_mode mode;
9662 {
9678 {
9683 }
9689 }
9690 }
9692 /* Mask out the tz least significant bits of X of type TYPE where
9693 tz is the number of trailing zeroes in Y. */
9694 static wide_int
9696 {
9701 }
9703 /* Return true when T is an address and is known to be nonzero.
9704 For floating point we further ensure that T is not denormal.
9705 Similar logic is present in nonzero_address in rtlanal.h.
9707 If the return value is based on the assumption that signed overflow
9708 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9709 change *STRICT_OVERFLOW_P. */
9711 static bool
9713 {
9717 /* Doing something useful for floating point would need more work. */
9723 {
9726 strict_overflow_p);
9732 strict_overflow_p);
9740 }
9743 {
9746 strict_overflow_p);
9754 strict_overflow_p);
9769 strict_overflow_p);
9773 strict_overflow_p);
9776 {
9788 }
9792 }
9794 }
9796 /* Return true when T is an address and is known to be nonzero.
9797 Handle warnings about undefined signed overflow. */
9799 static bool
9801 {
9808 "determining that expression is always "
9810 WARN_STRICT_OVERFLOW_MISC);
9812 }
9814 /* Fold a binary expression of code CODE and type TYPE with operands
9815 OP0 and OP1. LOC is the location of the resulting expression.
9816 Return the folded expression if folding is successful. Otherwise,
9817 return NULL_TREE. */
9819 tree
9822 {
9837 /* Strip any conversions that don't change the mode. This is
9838 safe for every expression, except for a comparison expression
9839 because its signedness is derived from its operands. So, in
9840 the latter case, only strip conversions that don't change the
9841 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9842 preserved.
9844 Note that this is done as an internal manipulation within the
9845 constant folder, in order to find the simplest representation
9846 of the arguments so that their form can be studied. In any
9847 cases, the appropriate type conversions should be put back in
9848 the tree that will get out of the constant folder. */
9851 {
9854 }
9855 else
9856 {
9859 }
9861 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9862 constant but we can't do arithmetic on them. */
9864 {
9867 {
9871 }
9872 }
9874 /* If this is a commutative operation, and ARG0 is a constant, move it
9875 to ARG1 to reduce the number of tests below. */
9880 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9881 to ARG1 to reduce the number of tests below. */
9890 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9892 First check for cases where an arithmetic operation is applied to a
9893 compound, conditional, or comparison operation. Push the arithmetic
9894 operation inside the compound or conditional to see if any folding
9895 can then be done. Convert comparison to conditional for this purpose.
9896 The also optimizes non-constant cases that used to be done in
9897 expand_expr.
9899 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9900 one of the operands is a comparison and the other is a comparison, a
9901 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9902 code below would make the expression more complex. Change it to a
9903 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9904 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9917 {
9921 boolean_type_node,
9929 }
9933 {
9935 {
9940 tem);
9941 }
9944 {
9949 tem);
9950 }
9955 {
9961 }
9966 {
9972 }
9973 }
9976 {
9978 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9981 {
9987 }
9989 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9992 {
9993 tree base;
9994 HOST_WIDE_INT coffset;
10003 }
10008 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10014 arg1),
10016 arg0)));
10022 {
10023 /* X + (X / CST) * -CST is X % CST. */
10028 {
10037 cst0));
10038 }
10039 }
10041 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10042 one. Make sure the type is not saturating and has the signedness of
10043 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10044 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10051 {
10055 }
10058 {
10059 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10060 with a constant, and the two constants have no bits in common,
10061 we should treat this as a BIT_IOR_EXPR since this may produce more
10062 simplifications. */
10069 {
10072 }
10074 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10075 (plus (plus (mult) (mult)) (foo)) so that we can
10076 take advantage of the factoring cases below. */
10084 {
10090 else
10103 parg0),
10105 marg)),
10109 return
10115 parg1)));
10116 }
10117 }
10118 else
10119 {
10120 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10121 to __complex__ ( x, y ). This is not the same for SNaNs or
10122 if signed zeros are involved. */
10126 {
10133 {
10137 {
10143 }
10145 {
10151 }
10152 }
10153 }
10161 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10162 We associate floats only if the user has specified
10163 -fassociative-math. */
10167 {
10172 {
10173 tree tree0;
10176 }
10177 }
10178 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10179 We associate floats only if the user has specified
10180 -fassociative-math. */
10184 {
10189 {
10190 tree tree0;
10193 }
10194 }
10195 }
10197 bit_rotate:
10198 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10199 is a rotate of A by C1 bits. */
10200 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10201 is a rotate of A by B bits. */
10202 {
10204 tree rtype;
10213 /* Only create rotates in complete modes. Other cases are not
10214 expanded properly. */
10217 {
10231 {
10237 }
10239 {
10247 element_precision
10251 return
10254 ? LROTATE_EXPR
10258 }
10260 {
10268 element_precision
10272 return fold_convert_loc
10275 ? LROTATE_EXPR
10279 }
10280 }
10281 }
10283 associate:
10284 /* In most languages, can't associate operations on floats through
10285 parentheses. Rather than remember where the parentheses were, we
10286 don't associate floats at all, unless the user has specified
10287 -fassociative-math.
10288 And, we need to make sure type is not saturating. */
10292 {
10298 /* Split both trees into variables, constants, and literals. Then
10299 associate each group together, the constants with literals,
10300 then the result with variables. This increases the chances of
10301 literals being recombined later and of generating relocatable
10302 expressions for the sum of a constant and literal. */
10307 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10311 /* With undefined overflow prefer doing association in a type
10312 which wraps on overflow, if that is one of the operand types. */
10315 {
10323 }
10325 /* With undefined overflow we can only associate constants with one
10326 variable, and constants whose association doesn't overflow. */
10329 {
10331 {
10349 /* The only case we can still associate with two variables
10350 is if they are the same, modulo negation and bit-pattern
10351 preserving conversions. */
10354 }
10355 }
10357 /* Only do something if we found more than two objects. Otherwise,
10358 nothing has changed and we risk infinite recursion. */
10364 {
10376 /* Preserve the MINUS_EXPR if the negative part of the literal is
10377 greater than the positive part. Otherwise, the multiplicative
10378 folding code (i.e extract_muldiv) may be fooled in case
10379 unsigned constants are subtracted, like in the following
10380 example: ((X*2 + 4) - 8U)/2. */
10382 {
10386 {
10390 }
10391 else
10392 {
10396 }
10397 }
10399 /* Don't introduce overflows through reassociation. */
10406 {
10408 return
10412 else
10413 {
10416 return
10420 }
10421 }
10424 return
10427 }
10428 }
10433 /* Pointer simplifications for subtraction, simple reassociations. */
10435 {
10436 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10439 {
10449 }
10450 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10452 {
10459 }
10460 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10461 simplifies. */
10463 {
10470 arg10);
10473 }
10474 }
10475 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10485 /* X - (X / Y) * Y is X % Y. */
10493 return
10499 {
10500 /* Fold A - (A & B) into ~B & A. */
10503 {
10505 {
10512 }
10514 {
10521 }
10522 }
10524 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10525 any power of 2 minus 1. */
10530 {
10536 {
10540 }
10541 }
10542 }
10544 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10545 __complex__ ( x, -y ). This is not the same for SNaNs or if
10546 signed zeros are involved. */
10550 {
10557 {
10561 {
10563 arg1r ? arg1r
10568 }
10570 {
10574 arg1i ? arg1i
10577 }
10578 }
10579 }
10581 /* A - B -> A + (-B) if B is easily negatable. */
10585 /* Avoid this transformation if B is a positive REAL_CST. */
10594 /* Try folding difference of addresses. */
10595 {
10596 HOST_WIDE_INT diff;
10602 }
10604 /* Fold &a[i] - &a[j] to i-j. */
10609 {
10615 }
10618 && flag_unsafe_math_optimizations
10624 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10625 one. Make sure the type is not saturating and has the signedness of
10626 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10627 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10634 {
10638 }
10643 /* (-A) * (-B) -> A * B */
10658 {
10659 /* Transform x * -C into -x * C if x is easily negatable. */
10668 tem);
10670 /* (a * (1 << b)) is (a << b) */
10680 /* (A + A) * C -> A * 2 * C */
10692 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10693 sign-changing only. */
10703 {
10706 "occur when simplifying "
10708 WARN_STRICT_OVERFLOW_MISC);
10710 }
10712 /* Optimize z * conj(z) for integer complex numbers. */
10719 }
10720 else
10721 {
10722 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10723 the result for floating point types due to rounding so it is applied
10724 only if -fassociative-math was specify. */
10729 {
10731 arg1);
10735 }
10737 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10739 {
10742 {
10745 }
10746 }
10748 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10749 This is not the same for NaNs or if signed zeros are
10750 involved. */
10756 {
10759 return
10765 return
10770 }
10772 /* Optimize z * conj(z) for floating point complex numbers.
10773 Guarded by flag_unsafe_math_optimizations as non-finite
10774 imaginary components don't produce scalar results. */
10785 {
10789 /* Optimizations of root(...)*root(...). */
10791 {
10796 /* Optimize sqrt(x)*sqrt(x) as x. */
10802 /* Optimize root(x)*root(y) as root(x*y). */
10806 }
10808 /* Optimize expN(x)*expN(y) as expN(x+y). */
10810 {
10816 }
10818 /* Optimizations of pow(...)*pow(...). */
10822 {
10828 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10830 {
10835 }
10837 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10839 {
10844 }
10845 }
10847 /* Optimize tan(x)*cos(x) as sin(x). */
10856 {
10862 }
10864 /* Optimize x*pow(x,c) as pow(x,c+1). */
10868 {
10874 {
10876 REAL_VALUE_TYPE c;
10877 tree arg;
10883 }
10884 }
10886 /* Optimize pow(x,c)*x as pow(x,c+1). */
10890 {
10896 {
10898 REAL_VALUE_TYPE c;
10899 tree arg;
10905 }
10906 }
10908 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10910 && optimize
10912 {
10916 {
10919 }
10920 }
10921 }
10922 }
10926 bit_ior:
10927 /* ~X | X is -1. */
10930 {
10934 }
10936 /* X | ~X is -1. */
10939 {
10943 }
10945 /* Canonicalize (X & C1) | C2. */
10949 {
10954 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10962 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10967 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10968 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10969 mode which allows further optimizations. */
10974 {
10978 {
10981 }
10982 }
10989 c3)),
10990 arg1);
10991 }
10993 /* (X & ~Y) | (~X & Y) is X ^ Y */
10996 {
11013 }
11019 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11021 This results in more efficient code for machines without a NAND
11022 instruction. Combine will canonicalize to the first form
11023 which will allow use of NAND instructions provided by the
11024 backend if they exist. */
11027 {
11028 return
11035 }
11037 /* See if this can be simplified into a rotate first. If that
11038 is unsuccessful continue in the association code. */
11042 /* ~X ^ X is -1. */
11045 {
11049 }
11051 /* X ^ ~X is -1. */
11054 {
11058 }
11060 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11061 with a constant, and the two constants have no bits in common,
11062 we should treat this as a BIT_IOR_EXPR since this may produce more
11063 simplifications. */
11070 {
11073 }
11075 /* (X | Y) ^ X -> Y & ~ X*/
11078 {
11081 arg1);
11086 }
11088 /* (Y | X) ^ X -> Y & ~ X*/
11091 {
11094 arg1);
11099 }
11101 /* X ^ (X | Y) -> Y & ~ X*/
11104 {
11107 arg0);
11112 }
11114 /* X ^ (Y | X) -> Y & ~ X*/
11117 {
11120 arg0);
11125 }
11127 /* Convert ~X ^ ~Y to X ^ Y. */
11136 /* Convert ~X ^ C to X ^ ~C. */
11144 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11152 /* Fold (X & Y) ^ Y as ~X & Y. */
11155 {
11160 }
11161 /* Fold (X & Y) ^ X as ~Y & X. */
11165 {
11170 }
11171 /* Fold X ^ (X & Y) as X & ~Y. */
11174 {
11179 }
11180 /* Fold X ^ (Y & X) as ~Y & X. */
11184 {
11189 }
11191 /* See if this can be simplified into a rotate first. If that
11192 is unsuccessful continue in the association code. */
11196 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11204 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11212 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11217 {
11218 tree tem2;
11225 }
11226 /* Fold ~X & 1 as (X & 1) == 0. */
11230 {
11231 tree tem2;
11238 }
11239 /* Fold !X & 1 as X == 0. */
11242 {
11246 }
11248 /* Fold (X ^ Y) & Y as ~X & Y. */
11251 {
11256 }
11257 /* Fold (X ^ Y) & X as ~Y & X. */
11261 {
11266 }
11267 /* Fold X & (X ^ Y) as X & ~Y. */
11270 {
11275 }
11276 /* Fold X & (Y ^ X) as ~Y & X. */
11280 {
11285 }
11287 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11288 multiple of 1 << CST. */
11290 {
11297 }
11299 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11300 bits from CST2. */
11304 {
11312 {
11313 /* Avoid the transform if arg1 is a mask of some
11314 mode which allows further optimizations. */
11321 }
11322 }
11324 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11325 ((A & N) + B) & M -> (A + B) & M
11326 Similarly if (N & M) == 0,
11327 ((A | N) + B) & M -> (A + B) & M
11328 and for - instead of + (or unary - instead of +)
11329 and/or ^ instead of |.
11330 If B is constant and (B & M) == 0, fold into A & M. */
11332 {
11341 {
11344 wide_int cst0;
11346 /* Now we know that arg0 is (C + D) or (C - D) or
11347 -C and arg1 (M) is == (1LL << cst) - 1.
11348 Store C into PMOP[0] and D into PMOP[1]. */
11352 {
11355 }
11362 {
11372 {
11375 }
11378 /* If C or D is of the form (A & N) where
11379 (N & M) == M, or of the form (A | N) or
11380 (A ^ N) where (N & M) == 0, replace it with A. */
11384 /* If C or D is a N where (N & M) == 0, it can be
11385 omitted (assumed 0). */
11393 }
11395 /* Only build anything new if we optimized one or both arguments
11396 above. */
11400 {
11403 {
11404 /* Perform the operations in a type that has defined
11405 overflow behavior. */
11411 }
11416 {
11424 else
11426 }
11429 else
11432 /* TEM is now the new binary +, - or unary - replacement. */
11436 }
11437 }
11438 }
11443 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11446 {
11451 return
11453 }
11455 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11457 This results in more efficient code for machines without a NOR
11458 instruction. Combine will canonicalize to the first form
11459 which will allow use of NOR instructions provided by the
11460 backend if they exist. */
11463 {
11470 }
11472 /* If arg0 is derived from the address of an object or function, we may
11473 be able to fold this expression using the object or function's
11474 alignment. */
11476 {
11483 /* This works because modulus is a power of 2. If this weren't the
11484 case, we'd have to replace it by its greatest power-of-2
11485 divisor: modulus & -modulus. */
11488 }
11490 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11491 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11492 if the new mask might be further optimized. */
11501 {
11512 {
11515 /* See if more bits can be proven as zero because of
11516 zero extension. */
11519 {
11524 {
11526 /* See if we can shorten the right shift. */
11529 /* Otherwise X >> C1 is all zeros, so we'll optimize
11530 it into (X, 0) later on by making sure zerobits
11531 is all ones. */
11532 }
11533 }
11536 {
11539 }
11540 /* For arithmetic shift if sign bit could be set, zerobits
11541 can contain actually sign bits, so no transformation is
11542 possible, unless MASK masks them all away. In that
11543 case the shift needs to be converted into logical shift. */
11546 {
11549 else
11551 }
11552 }
11554 /* ((X << 16) & 0xff00) is (X, 0). */
11561 {
11562 /* Only do the transformation if NEWMASK is some integer
11563 mode's mask. */
11570 {
11571 tree newmaskt;
11574 {
11580 }
11581 else
11586 }
11587 }
11588 }
11593 /* Don't touch a floating-point divide by zero unless the mode
11594 of the constant can represent infinity. */
11600 /* (-A) / (-B) -> A / B */
11610 /* Convert A/B/C to A/(B*C). */
11617 /* Convert A/(B/C) to (A/B)*C. */
11625 /* Convert C1/(X*C2) into (C1/C2)/X. */
11630 {
11636 }
11639 {
11643 /* Optimize sin(x)/cos(x) as tan(x). */
11649 {
11654 }
11656 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11662 {
11666 {
11671 }
11672 }
11674 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11675 NaNs or Infinities. */
11679 {
11686 {
11691 }
11692 }
11694 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11695 NaNs or Infinities. */
11699 {
11706 {
11710 {
11714 tmp);
11715 }
11716 }
11717 }
11719 /* Optimize pow(x,c)/x as pow(x,c-1). */
11723 {
11729 {
11731 REAL_VALUE_TYPE c;
11732 tree arg;
11738 }
11739 }
11741 /* Optimize a/root(b/c) into a*root(c/b). */
11743 {
11747 {
11756 }
11757 }
11759 /* Optimize x/expN(y) into x*expN(-y). */
11761 {
11768 }
11770 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11774 {
11782 }
11783 }
11787 /* Optimize (X & (-A)) / A where A is a power of 2,
11788 to X >> log2(A) */
11792 {
11800 }
11801 }
11803 /* Fall through */
11806 /* Simplify A / (B << N) where A and B are positive and B is
11807 a power of 2, to A >> (N + log2(B)). */
11812 {
11815 {
11823 WARN_STRICT_OVERFLOW_MISC);
11829 }
11830 }
11832 /* Fall through */
11840 /* Convert -A / -B to A / B when the type is signed and overflow is
11841 undefined. */
11845 {
11848 "when distributing negation across "
11850 WARN_STRICT_OVERFLOW_MISC);
11856 }
11860 {
11863 "when distributing negation across "
11865 WARN_STRICT_OVERFLOW_MISC);
11871 }
11873 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11874 operation, EXACT_DIV_EXPR.
11876 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11877 At one time others generated faster code, it's not clear if they do
11878 after the last round to changes to the DIV code in expmed.c. */
11887 {
11891 WARN_STRICT_OVERFLOW_MISC);
11893 }
11901 /* X % -Y is the same as X % Y. */
11914 {
11918 WARN_STRICT_OVERFLOW_MISC);
11920 }
11922 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11923 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11927 {
11929 /* Also optimize A % (C << N) where C is a power of 2,
11930 to A & ((C << N) - 1). */
11935 {
11936 tree mask
11941 "occur when simplifying "
11943 WARN_STRICT_OVERFLOW_MISC);
11947 }
11948 }
11956 /* Since negative shift count is not well-defined,
11957 don't try to compute it in the compiler. */
11963 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11968 {
11972 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11973 being well defined. */
11975 {
11981 else
11983 }
11987 }
11989 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11990 into x & ((unsigned)-1 >> c) for unsigned types. */
11998 {
12001 tree lshift;
12002 tree arg00;
12005 {
12012 }
12013 }
12015 /* If we have a rotate of a bit operation with the rotate count and
12016 the second operand of the bit operation both constant,
12017 permute the two operations. */
12029 /* Two consecutive rotates adding up to the some integer
12030 multiple of the precision of the type can be ignored. */
12038 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12039 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12040 if the latter can be further optimized. */
12045 {
12049 arg1);
12053 arg1);
12057 }
12074 /* Note that the operands of this must be ints
12075 and their values must be 0 or 1.
12076 ("true" is a fixed value perhaps depending on the language.) */
12077 /* If first arg is constant zero, return it. */
12081 /* If either arg is constant true, drop it. */
12085 /* Preserve sequence points. */
12088 /* If second arg is constant zero, result is zero, but first arg
12089 must be evaluated. */
12092 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12093 case will be handled here. */
12097 /* !X && X is always false. */
12101 /* X && !X is always false. */
12106 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12107 means A >= Y && A != MAX, but in this case we know that
12108 A < X <= MAX. */
12112 {
12120 }
12129 /* Note that the operands of this must be ints
12130 and their values must be 0 or true.
12131 ("true" is a fixed value perhaps depending on the language.) */
12132 /* If first arg is constant true, return it. */
12136 /* If either arg is constant zero, drop it. */
12140 /* Preserve sequence points. */
12143 /* If second arg is constant true, result is true, but we must
12144 evaluate first arg. */
12147 /* Likewise for first arg, but note this only occurs here for
12148 TRUTH_OR_EXPR. */
12152 /* !X || X is always true. */
12156 /* X || !X is always true. */
12161 /* (X && !Y) || (!X && Y) is X ^ Y */
12164 {
12181 }
12190 /* If the second arg is constant zero, drop it. */
12193 /* If the second arg is constant true, this is a logical inversion. */
12195 {
12198 }
12199 /* Identical arguments cancel to zero. */
12203 /* !X ^ X is always true. */
12208 /* X ^ !X is always true. */
12224 /* bool_var != 0 becomes bool_var. */
12229 /* bool_var == 1 becomes bool_var. */
12234 /* bool_var != 1 becomes !bool_var. */
12241 /* bool_var == 0 becomes !bool_var. */
12248 /* !exp != 0 becomes !exp */
12253 /* If this is an equality comparison of the address of two non-weak,
12254 unaliased symbols neither of which are extern (since we do not
12255 have access to attributes for externs), then we know the result. */
12260 {
12268 else
12273 type);
12274 }
12276 /* Similarly for a NEGATE_EXPR. */
12280 arg1)))
12285 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12293 arg1),
12296 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12305 {
12309 val,
12313 }
12315 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12322 {
12324 code == NE_EXPR
12327 }
12329 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12334 /* If this is an EQ or NE comparison with zero and ARG0 is
12335 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12336 two operations, but the latter can be done in one less insn
12337 on machines that have only two-operand insns or on which a
12338 constant cannot be the first operand. */
12341 {
12346 {
12353 arg1);
12354 }
12357 {
12364 arg1);
12365 }
12366 }
12368 /* If this is an NE or EQ comparison of zero against the result of a
12369 signed MOD operation whose second operand is a power of 2, make
12370 the MOD operation unsigned since it is simpler and equivalent. */
12378 {
12388 }
12390 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12391 C1 is a valid shift constant, and C2 is a power of two, i.e.
12392 a single bit. */
12396 == INTEGER_CST
12399 {
12404 /* Check for a valid shift count. */
12406 {
12410 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12411 can be rewritten as (X & (C2 << C1)) != 0. */
12413 {
12418 }
12419 /* Otherwise, for signed (arithmetic) shifts,
12420 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12421 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12425 /* Otherwise, of unsigned (logical) shifts,
12426 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12427 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12428 else
12432 arg000);
12433 }
12434 }
12436 /* If we have (A & C) == C where C is a power of 2, convert this into
12437 (A & C) != 0. Similarly for NE_EXPR. */
12443 integer_zero_node));
12445 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12446 bit, then fold the expression into A < 0 or A >= 0. */
12451 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12452 Similarly for NE_EXPR. */
12456 {
12460 tree dandnotc
12463 notc);
12467 }
12469 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12470 Similarly for NE_EXPR. */
12474 {
12476 tree candnotd
12483 }
12485 /* If this is a comparison of a field, we may be able to simplify it. */
12488 /* Handle the constant case even without -O
12489 to make sure the warnings are given. */
12491 {
12495 }
12497 /* Optimize comparisons of strlen vs zero to a compare of the
12498 first character of the string vs zero. To wit,
12499 strlen(ptr) == 0 => *ptr == 0
12500 strlen(ptr) != 0 => *ptr != 0
12501 Other cases should reduce to one of these two (or a constant)
12502 due to the return value of strlen being unsigned. */
12505 {
12513 {
12518 }
12519 }
12521 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12522 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12526 {
12531 {
12533 {
12536 }
12539 }
12540 }
12542 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12548 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12553 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12560 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12568 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12569 (X & C) == 0 when C is a single bit. */
12574 {
12581 arg1));
12582 }
12584 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12585 constant C is a power of two, i.e. a single bit. */
12592 {
12596 }
12598 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12599 when is C is a power of two, i.e. a single bit. */
12606 {
12612 }
12616 {
12619 }
12621 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12629 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12632 {
12645 arg01),
12654 arg01),
12663 arg00),
12672 arg00),
12674 }
12678 {
12685 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12686 operand_equal_p guarantees no side-effects so we don't need
12687 to use omit_one_operand on Z. */
12691 arg10));
12695 arg11));
12699 arg10));
12703 arg11));
12705 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12708 {
12714 }
12715 }
12717 /* Attempt to simplify equality/inequality comparisons of complex
12718 values. Only lower the comparison if the result is known or
12719 can be simplified to a single scalar comparison. */
12724 {
12729 {
12732 }
12733 else
12734 {
12737 }
12740 {
12743 }
12744 else
12745 {
12748 }
12752 {
12754 {
12759 }
12760 else
12761 {
12766 }
12767 }
12771 {
12773 {
12778 }
12779 else
12780 {
12785 }
12786 }
12787 }
12799 /* Transform comparisons of the form X +- C CMP X. */
12806 {
12813 else
12816 /* (X - c) > X becomes false. */
12820 {
12824 "occur when assuming that (X - c) > X "
12826 WARN_STRICT_OVERFLOW_ALL);
12828 }
12830 /* Likewise (X + c) < X becomes false. */
12834 {
12838 "occur when assuming that "
12840 WARN_STRICT_OVERFLOW_ALL);
12842 }
12844 /* Convert (X - c) <= X to true. */
12849 {
12853 "occur when assuming that "
12855 WARN_STRICT_OVERFLOW_ALL);
12857 }
12859 /* Convert (X + c) >= X to true. */
12864 {
12868 "occur when assuming that "
12870 WARN_STRICT_OVERFLOW_ALL);
12872 }
12875 {
12876 /* Convert X + c > X and X - c < X to true for integers. */
12880 {
12883 "not occur when assuming that "
12885 WARN_STRICT_OVERFLOW_ALL);
12887 }
12892 {
12895 "not occur when assuming that "
12897 WARN_STRICT_OVERFLOW_ALL);
12899 }
12901 /* Convert X + c <= X and X - c >= X to false for integers. */
12905 {
12908 "not occur when assuming that "
12910 WARN_STRICT_OVERFLOW_ALL);
12912 }
12917 {
12920 "not occur when assuming that "
12922 WARN_STRICT_OVERFLOW_ALL);
12924 }
12925 }
12926 }
12928 /* Comparisons with the highest or lowest possible integer of
12929 the specified precision will have known values. */
12930 {
12936 {
12943 {
12956 /* The GE_EXPR and LT_EXPR cases above are not normally
12957 reached because of previous transformations. */
12961 }
12964 {
12971 arg1);
12977 arg0),
12978 arg1);
12981 }
12984 {
12999 }
13002 {
13009 arg1);
13015 arg0),
13016 arg1);
13019 }
13023 /* We will flip the signedness of the comparison operator
13024 associated with the mode of arg1, so the sign bit is
13025 specified by this mode. Check that arg1 is the signed
13026 max associated with this sign bit. */
13028 /* signed_type does not work on pointer types. */
13030 {
13031 /* The following case also applies to X < signed_max+1
13032 and X >= signed_max+1 because previous transformations. */
13034 {
13040 }
13041 }
13042 }
13043 }
13045 /* If we are comparing an ABS_EXPR with a constant, we can
13046 convert all the cases into explicit comparisons, but they may
13047 well not be faster than doing the ABS and one comparison.
13048 But ABS (X) <= C is a range comparison, which becomes a subtraction
13049 and a comparison, and is probably faster. */
13063 /* Convert ABS_EXPR<x> >= 0 to true. */
13070 {
13073 "when simplifying comparison of "
13075 WARN_STRICT_OVERFLOW_CONDITIONAL);
13078 arg0);
13079 }
13081 /* Convert ABS_EXPR<x> < 0 to false. */
13086 {
13089 "when simplifying comparison of "
13091 WARN_STRICT_OVERFLOW_CONDITIONAL);
13094 arg0);
13095 }
13097 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13098 and similarly for >= into !=. */
13108 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13109 otherwise Y might be >= # of bits in X's type and thus e.g.
13110 (unsigned char) (1 << Y) for Y 15 might be 0.
13111 If the cast is widening, then 1 << Y should have unsigned type,
13112 otherwise if Y is number of bits in the signed shift type minus 1,
13113 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13114 31 might be 0xffffffff80000000. */
13125 {
13131 }
13144 {
13148 }
13150 /* If the first operand is NaN, the result is constant. */
13154 {
13156 ? integer_zero_node
13159 }
13161 /* If the second operand is NaN, the result is constant. */
13165 {
13167 ? integer_zero_node
13170 }
13172 /* Simplify unordered comparison of something with itself. */
13178 && !flag_trapping_math
13182 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13183 {
13195 }
13200 /* When pedantic, a compound expression can be neither an lvalue
13201 nor an integer constant expression. */
13204 /* Don't let (0, 0) be null pointer constant. */
13210 /* An ASSERT_EXPR should never be passed to fold_binary. */
13216 }
13218 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13219 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13220 of GOTO_EXPR. */
13222 static tree
13224 {
13226 {
13233 /* ... fall through ... */
13237 }
13238 }
13240 /* Return whether the sub-tree ST contains a label which is accessible from
13241 outside the sub-tree. */
13243 static bool
13245 {
13246 return
13248 }
13250 /* Fold a ternary expression of code CODE and type TYPE with operands
13251 OP0, OP1, and OP2. Return the folded expression if folding is
13252 successful. Otherwise, return NULL_TREE. */
13254 tree
13257 {
13258 tree tem;
13265 /* If this is a commutative operation, and OP0 is a constant, move it
13266 to OP1 to reduce the number of tests below. */
13275 /* Strip any conversions that don't change the mode. This is safe
13276 for every expression, except for a comparison expression because
13277 its signedness is derived from its operands. So, in the latter
13278 case, only strip conversions that don't change the signedness.
13280 Note that this is done as an internal manipulation within the
13281 constant folder, in order to find the simplest representation of
13282 the arguments so that their form can be studied. In any cases,
13283 the appropriate type conversions should be put back in the tree
13284 that will get out of the constant folder. */
13286 {
13289 }
13292 {
13295 }
13298 {
13301 }
13304 {
13308 {
13314 }
13319 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13320 so all simple results must be passed through pedantic_non_lvalue. */
13322 {
13325 /* Only optimize constant conditions when the selected branch
13326 has the same type as the COND_EXPR. This avoids optimizing
13327 away "c ? x : throw", where the throw has a void type.
13328 Avoid throwing away that operand which contains label. */
13335 }
13337 {
13342 {
13347 {
13355 }
13359 }
13360 }
13362 /* If we have A op B ? A : C, we may be able to convert this to a
13363 simpler expression, depending on the operation and the values
13364 of B and C. Signed zeros prevent all of these transformations,
13365 for reasons given above each one.
13367 Also try swapping the arguments and inverting the conditional. */
13372 {
13376 }
13380 op2,
13383 {
13387 {
13391 }
13392 }
13394 /* If the second operand is simpler than the third, swap them
13395 since that produces better jump optimization results. */
13398 {
13400 /* See if this can be inverted. If it can't, possibly because
13401 it was a floating-point inequality comparison, don't do
13402 anything. */
13406 }
13408 /* Convert A ? 1 : 0 to simply A. */
13413 /* If we try to convert OP0 to our type, the
13414 call to fold will try to move the conversion inside
13415 a COND, which will recurse. In that case, the COND_EXPR
13416 is probably the best choice, so leave it alone. */
13420 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13421 over COND_EXPR in cases such as floating point comparisons. */
13430 arg0)));
13432 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13437 {
13438 /* sign_bit_p looks through both zero and sign extensions,
13439 but for this optimization only sign extensions are
13440 usable. */
13443 {
13446 {
13449 }
13451 }
13452 /* sign_bit_p only checks ARG1 bits within A's precision.
13453 If <sign bit of A> has wider type than A, bits outside
13454 of A's precision in <sign bit of A> need to be checked.
13455 If they are all 0, this optimization needs to be done
13456 in unsigned A's type, if they are all 1 in signed A's type,
13457 otherwise this can't be done. */
13463 {
13465 tree tem_type;
13478 {
13481 }
13483 {
13486 }
13487 else
13489 }
13492 return
13498 arg1)));
13499 }
13501 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13502 already handled above. */
13507 {
13516 }
13518 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13519 is probably obsolete because the first operand should be a
13520 truth value (that's why we have the two cases above), but let's
13521 leave it in until we can confirm this for all front-ends. */
13533 /* Disable the transformations below for vectors, since
13534 fold_binary_op_with_conditional_arg may undo them immediately,
13535 yielding an infinite loop. */
13539 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13548 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13553 {
13555 /* Only perform transformation if ARG0 is easily inverted. */
13559 ? BIT_IOR_EXPR
13562 arg1);
13563 }
13565 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13570 {
13572 /* Only perform transformation if ARG0 is easily inverted. */
13578 op2);
13579 }
13581 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13593 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13594 of fold_ternary on them. */
13604 {
13614 {
13619 {
13627 }
13629 /* Constructor elements can be subvectors. */
13632 {
13636 }
13638 /* We keep an exact subset of the constructor elements. */
13640 {
13646 {
13650 }
13658 CONSTRUCTOR_ELT
13661 }
13662 /* The bitfield references a single constructor element. */
13664 {
13669 else
13673 }
13674 }
13675 }
13677 /* A bit-field-ref that referenced the full argument can be stripped. */
13683 /* On constants we can use native encode/interpret to constant
13684 fold (nearly) all BIT_FIELD_REFs. */
13688 /* This limitation should not be necessary, we just need to
13689 round this up to mode size. */
13691 /* Need bit-shifting of the buffer to relax the following. */
13693 {
13698 /* ??? We cannot tell native_encode_expr to start at
13699 some random byte only. So limit us to a reasonable amount
13700 of work. */
13702 {
13707 {
13713 }
13714 }
13715 }
13720 /* For integers we can decompose the FMA if possible. */
13732 {
13748 {
13753 /* Make sure that the perm value is in an acceptable
13754 range. */
13763 else
13768 }
13771 {
13776 }
13781 {
13786 }
13792 {
13796 }
13801 /* Some targets are deficient and fail to expand a single
13802 argument permutation while still allowing an equivalent
13803 2-argument version. */
13807 {
13810 }
13813 {
13820 }
13824 }
13830 }
13832 /* Perform constant folding and related simplification of EXPR.
13833 The related simplifications include x*1 => x, x*0 => 0, etc.,
13834 and application of the associative law.
13835 NOP_EXPR conversions may be removed freely (as long as we
13836 are careful not to change the type of the overall expression).
13837 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13838 but we can constant-fold them if they have constant operands. */
13840 #ifdef ENABLE_FOLD_CHECKING
13841 # define fold(x) fold_1 (x)
13843 static
13844 #endif
13845 tree
13847 {
13851 tree tem;
13854 /* Return right away if a constant. */
13858 /* CALL_EXPR-like objects with variable numbers of operands are
13859 treated specially. */
13861 {
13863 {
13866 }
13868 }
13871 {
13876 {
13894 }
13895 }
13898 {
13900 {
13907 {
13912 /* Find a matching index by means of a binary search. */
13914 {
13930 else
13932 }
13933 }
13936 }
13938 /* Return a VECTOR_CST if possible. */
13940 {
13947 tree value;
13950 {
13954 {
13957 }
13958 else
13960 }
13965 }
13973 }
13975 #ifdef ENABLE_FOLD_CHECKING
13976 #undef fold
13983 /* When --enable-checking=fold, compute a digest of expr before
13984 and after actual fold call to see if fold did not accidentally
13985 change original expr. */
13987 tree
13989 {
13990 tree ret;
14010 }
14012 void
14014 {
14025 }
14027 static void
14029 {
14031 }
14033 static void
14036 {
14042 recursive_label:
14052 {
14053 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14057 }
14064 {
14065 /* Allow these fields to be modified. */
14066 tree tmp;
14074 {
14077 }
14078 }
14089 {
14092 {
14107 }
14111 {
14124 }
14141 {
14147 }
14150 {
14152 {
14155 }
14157 }
14168 {
14171 }
14181 }
14182 }
14184 /* Helper function for outputting the checksum of a tree T. When
14185 debugging with gdb, you can "define mynext" to be "next" followed
14186 by "call debug_fold_checksum (op0)", then just trace down till the
14187 outputs differ. */
14189 DEBUG_FUNCTION void
14191 {
14206 }
14208 #endif
14210 /* Fold a unary tree expression with code CODE of type TYPE with an
14211 operand OP0. LOC is the location of the resulting expression.
14212 Return a folded expression if successful. Otherwise, return a tree
14213 expression with code CODE of type TYPE with an operand OP0. */
14215 tree
14218 {
14219 tree tem;
14220 #ifdef ENABLE_FOLD_CHECKING
14229 #endif
14235 #ifdef ENABLE_FOLD_CHECKING
14242 #endif
14244 }
14246 /* Fold a binary tree expression with code CODE of type TYPE with
14247 operands OP0 and OP1. LOC is the location of the resulting
14248 expression. Return a folded expression if successful. Otherwise,
14249 return a tree expression with code CODE of type TYPE with operands
14250 OP0 and OP1. */
14252 tree
14255 MEM_STAT_DECL)
14256 {
14257 tree tem;
14258 #ifdef ENABLE_FOLD_CHECKING
14275 #endif
14281 #ifdef ENABLE_FOLD_CHECKING
14296 #endif
14298 }
14300 /* Fold a ternary tree expression with code CODE of type TYPE with
14301 operands OP0, OP1, and OP2. Return a folded expression if
14302 successful. Otherwise, return a tree expression with code CODE of
14303 type TYPE with operands OP0, OP1, and OP2. */
14305 tree
14308 {
14309 tree tem;
14310 #ifdef ENABLE_FOLD_CHECKING
14334 #endif
14341 #ifdef ENABLE_FOLD_CHECKING
14364 #endif
14366 }
14368 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14369 arguments in ARGARRAY, and a null static chain.
14370 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14371 of type TYPE from the given operands as constructed by build_call_array. */
14373 tree
14376 {
14377 tree tem;
14378 #ifdef ENABLE_FOLD_CHECKING
14397 #endif
14403 #ifdef ENABLE_FOLD_CHECKING
14419 #endif
14421 }
14423 /* Perform constant folding and related simplification of initializer
14424 expression EXPR. These behave identically to "fold_buildN" but ignore
14425 potential run-time traps and exceptions that fold must preserve. */
14427 #define START_FOLD_INIT \
14428 int saved_signaling_nans = flag_signaling_nans;\
14429 int saved_trapping_math = flag_trapping_math;\
14430 int saved_rounding_math = flag_rounding_math;\
14431 int saved_trapv = flag_trapv;\
14432 int saved_folding_initializer = folding_initializer;\
14433 flag_signaling_nans = 0;\
14434 flag_trapping_math = 0;\
14435 flag_rounding_math = 0;\
14436 flag_trapv = 0;\
14437 folding_initializer = 1;
14439 #define END_FOLD_INIT \
14440 flag_signaling_nans = saved_signaling_nans;\
14441 flag_trapping_math = saved_trapping_math;\
14442 flag_rounding_math = saved_rounding_math;\
14443 flag_trapv = saved_trapv;\
14444 folding_initializer = saved_folding_initializer;
14446 tree
14449 {
14450 tree result;
14451 START_FOLD_INIT;
14455 END_FOLD_INIT;
14457 }
14459 tree
14462 {
14463 tree result;
14464 START_FOLD_INIT;
14468 END_FOLD_INIT;
14470 }
14472 tree
14475 {
14476 tree result;
14477 START_FOLD_INIT;
14481 END_FOLD_INIT;
14483 }
14485 #undef START_FOLD_INIT
14486 #undef END_FOLD_INIT
14488 /* Determine if first argument is a multiple of second argument. Return 0 if
14489 it is not, or we cannot easily determined it to be.
14491 An example of the sort of thing we care about (at this point; this routine
14492 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14493 fold cases do now) is discovering that
14495 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14497 is a multiple of
14499 SAVE_EXPR (J * 8)
14501 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14503 This code also handles discovering that
14505 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14507 is a multiple of 8 so we don't have to worry about dealing with a
14508 possible remainder.
14510 Note that we *look* inside a SAVE_EXPR only to determine how it was
14511 calculated; it is not safe for fold to do much of anything else with the
14512 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14513 at run time. For example, the latter example above *cannot* be implemented
14514 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14515 evaluation time of the original SAVE_EXPR is not necessarily the same at
14516 the time the new expression is evaluated. The only optimization of this
14517 sort that would be valid is changing
14519 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14521 divided by 8 to
14523 SAVE_EXPR (I) * SAVE_EXPR (J)
14525 (where the same SAVE_EXPR (J) is used in the original and the
14526 transformed version). */
14528 int
14530 {
14538 {
14540 /* Bitwise and provides a power of two multiple. If the mask is
14541 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14544 /* FALLTHRU */
14557 {
14561 /* const_binop may not detect overflow correctly,
14562 so check for it explicitly here. */
14566 size_one_node,
14567 op1)))
14570 }
14574 /* Can't handle conversions from non-integral or wider integral type. */
14580 /* .. fall through ... */
14597 SIGNED);
14601 }
14602 }
14604 /* Return true if CODE or TYPE is known to be non-negative. */
14606 static bool
14608 {
14611 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14612 have a signed:1 type (where the value is -1 and 0). */
14615 }
14617 /* Return true if (CODE OP0) is known to be non-negative. If the return
14618 value is based on the assumption that signed overflow is undefined,
14619 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14620 *STRICT_OVERFLOW_P. */
14622 bool
14625 {
14630 {
14632 /* We can't return 1 if flag_wrapv is set because
14633 ABS_EXPR<INT_MIN> = INT_MIN. */
14637 {
14640 }
14647 strict_overflow_p);
14649 CASE_CONVERT:
14650 {
14655 {
14658 strict_overflow_p);
14660 {
14664 strict_overflow_p);
14665 }
14666 }
14668 {
14671 strict_overflow_p);
14675 }
14676 }
14681 }
14683 /* We don't know sign of `t', so be conservative and return false. */
14685 }
14687 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14688 value is based on the assumption that signed overflow is undefined,
14689 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14690 *STRICT_OVERFLOW_P. */
14692 bool
14695 {
14700 {
14705 strict_overflow_p)
14707 strict_overflow_p));
14709 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14710 both unsigned and at least 2 bits shorter than the result. */
14714 {
14719 {
14723 }
14724 }
14729 {
14730 /* x * x is always non-negative for floating point x
14731 or without overflow. */
14735 {
14739 }
14740 }
14742 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14743 both unsigned and their total bits is shorter than the result. */
14747 {
14766 {
14776 }
14777 }
14783 strict_overflow_p)
14785 strict_overflow_p));
14796 strict_overflow_p)
14798 strict_overflow_p));
14805 strict_overflow_p);
14808 }
14810 /* We don't know sign of `t', so be conservative and return false. */
14812 }
14814 /* Return true if T is known to be non-negative. If the return
14815 value is based on the assumption that signed overflow is undefined,
14816 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14817 *STRICT_OVERFLOW_P. */
14819 bool
14821 {
14826 {
14838 strict_overflow_p)
14840 strict_overflow_p));
14844 }
14845 /* We don't know sign of `t', so be conservative and return false. */
14847 }
14849 /* Return true if T is known to be non-negative. If the return
14850 value is based on the assumption that signed overflow is undefined,
14851 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14852 *STRICT_OVERFLOW_P. */
14854 bool
14857 {
14860 {
14880 /* Always true. */
14884 /* sqrt(-0.0) is -0.0. */
14888 strict_overflow_p);
14925 /* True if the 1st argument is nonnegative. */
14927 strict_overflow_p);
14930 /* True if the 1st OR 2nd arguments are nonnegative. */
14932 strict_overflow_p)
14934 strict_overflow_p)));
14937 /* True if the 1st AND 2nd arguments are nonnegative. */
14939 strict_overflow_p)
14941 strict_overflow_p)));
14944 /* True if the 2nd argument is nonnegative. */
14946 strict_overflow_p);
14949 /* True if the 1st argument is nonnegative or the second
14950 argument is an even integer. */
14955 strict_overflow_p);
14958 /* True if the 1st argument is nonnegative or the second
14959 argument is an even integer valued real. */
14961 {
14962 REAL_VALUE_TYPE c;
14963 HOST_WIDE_INT n;
14968 {
14969 REAL_VALUE_TYPE cint;
14973 }
14974 }
14976 strict_overflow_p);
14980 }
14982 type);
14983 }
14985 /* Return true if T is known to be non-negative. If the return
14986 value is based on the assumption that signed overflow is undefined,
14987 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14988 *STRICT_OVERFLOW_P. */
14990 static bool
14992 {
14998 {
15000 {
15004 /* If the initializer is non-void, then it's a normal expression
15005 that will be assigned to the slot. */
15009 /* Otherwise, the initializer sets the slot in some way. One common
15010 way is an assignment statement at the end of the initializer. */
15012 {
15020 else
15022 }
15026 strict_overflow_p);
15029 }
15032 {
15038 arg0,
15039 arg1,
15040 strict_overflow_p);
15041 }
15045 strict_overflow_p);
15048 strict_overflow_p);
15051 strict_overflow_p);
15056 }
15058 /* We don't know sign of `t', so be conservative and return false. */
15060 }
15062 /* Return true if T is known to be non-negative. If the return
15063 value is based on the assumption that signed overflow is undefined,
15064 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15065 *STRICT_OVERFLOW_P. */
15067 bool
15069 {
15076 {
15083 strict_overflow_p);
15089 strict_overflow_p);
15098 }
15101 {
15109 strict_overflow_p);
15114 strict_overflow_p);
15127 }
15128 }
15130 /* Return true if `t' is known to be non-negative. Handle warnings
15131 about undefined signed overflow. */
15133 bool
15135 {
15142 "determining that expression is always "
15144 WARN_STRICT_OVERFLOW_MISC);
15146 }
15149 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15150 For floating point we further ensure that T is not denormal.
15151 Similar logic is present in nonzero_address in rtlanal.h.
15153 If the return value is based on the assumption that signed overflow
15154 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15155 change *STRICT_OVERFLOW_P. */
15157 bool
15160 {
15162 {
15165 strict_overflow_p);
15168 {
15174 strict_overflow_p));
15175 }
15180 strict_overflow_p);
15184 }
15187 }
15189 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15190 For floating point we further ensure that T is not denormal.
15191 Similar logic is present in nonzero_address in rtlanal.h.
15193 If the return value is based on the assumption that signed overflow
15194 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15195 change *STRICT_OVERFLOW_P. */
15197 bool
15199 tree type,
15200 tree op0,
15202 {
15205 {
15209 {
15210 /* With the presence of negative values it is hard
15211 to say something. */
15218 /* One of operands must be positive and the other non-negative. */
15219 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15220 overflows, on a twos-complement machine the sum of two
15221 nonnegative numbers can never be zero. */
15223 strict_overflow_p)
15225 strict_overflow_p));
15226 }
15231 {
15233 strict_overflow_p)
15235 strict_overflow_p))
15236 {
15239 }
15240 }
15249 {
15252 }
15259 {
15263 /* When both operands are nonzero, then MAX must be too. */
15265 strict_overflow_p))
15268 /* MAX where operand 0 is positive is positive. */
15270 strict_overflow_p);
15271 }
15272 /* MAX where operand 1 is positive is positive. */
15277 {
15281 }
15286 strict_overflow_p)
15288 strict_overflow_p));
15292 }
15295 }
15297 /* Return true when T is an address and is known to be nonzero.
15298 For floating point we further ensure that T is not denormal.
15299 Similar logic is present in nonzero_address in rtlanal.h.
15301 If the return value is based on the assumption that signed overflow
15302 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15303 change *STRICT_OVERFLOW_P. */
15305 bool
15307 {
15310 {
15315 {
15324 /* For objects in symbol table check if we know they are non-zero.
15325 Don't do anything for variables and functions before symtab is built;
15326 it is quite possible that they will be declared weak later. */
15328 {
15334 else
15336 }
15338 /* Function local objects are never NULL. */
15345 /* Constants are never weak. */
15350 }
15358 {
15362 }
15367 }
15369 }
15371 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15372 attempt to fold the expression to a constant without modifying TYPE,
15373 OP0 or OP1.
15375 If the expression could be simplified to a constant, then return
15376 the constant. If the expression would not be simplified to a
15377 constant, then return NULL_TREE. */
15379 tree
15381 {
15384 }
15386 /* Given the components of a unary expression CODE, TYPE and OP0,
15387 attempt to fold the expression to a constant without modifying
15388 TYPE or OP0.
15390 If the expression could be simplified to a constant, then return
15391 the constant. If the expression would not be simplified to a
15392 constant, then return NULL_TREE. */
15394 tree
15396 {
15399 }
15401 /* If EXP represents referencing an element in a constant string
15402 (either via pointer arithmetic or array indexing), return the
15403 tree representing the value accessed, otherwise return NULL. */
15405 tree
15407 {
15411 {
15413 tree index;
15414 tree string;
15419 else
15420 {
15424 /* Optimize the special-case of a zero lower bound.
15426 We convert the low_bound to sizetype to avoid some problems
15427 with constant folding. (E.g. suppose the lower bound is 1,
15428 and its mode is QI. Without the conversion,l (ARRAY
15429 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15430 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15436 }
15449 }
15451 }
15453 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15454 an integer constant, real, or fixed-point constant.
15456 TYPE is the type of the result. */
15458 static tree
15460 {
15464 {
15466 {
15473 }
15480 {
15481 FIXED_VALUE_TYPE f;
15486 /* Propagate overflow flags. */
15490 }
15494 }
15497 }
15499 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15500 an integer constant or real constant.
15502 TYPE is the type of the result. */
15504 tree
15506 {
15510 {
15512 {
15513 /* If the value is unsigned or non-negative, then the absolute value
15514 is the same as the ordinary value. */
15518 /* If the value is negative, then the absolute value is
15519 its negation. */
15520 else
15521 {
15526 }
15527 }
15533 else
15539 }
15542 }
15544 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15545 constant. TYPE is the type of the result. */
15547 static tree
15549 {
15553 }
15555 /* Given CODE, a relational operator, the target type, TYPE and two
15556 constant operands OP0 and OP1, return the result of the
15557 relational operation. If the result is not a compile time
15558 constant, then return NULL_TREE. */
15560 static tree
15562 {
15565 /* From here on, the only cases we handle are when the result is
15566 known to be a constant. */
15569 {
15573 /* Handle the cases where either operand is a NaN. */
15575 {
15577 {
15605 }
15608 }
15611 }
15614 {
15618 }
15620 /* Handle equality/inequality of complex constants. */
15622 {
15633 else
15635 }
15638 {
15645 {
15657 }
15660 }
15662 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15664 To compute GT, swap the arguments and do LT.
15665 To compute GE, do LT and invert the result.
15666 To compute LE, swap the arguments, do LT and invert the result.
15667 To compute NE, do EQ and invert the result.
15669 Therefore, the code below must handle only EQ and LT. */
15672 {
15677 }
15679 /* Note that it is safe to invert for real values here because we
15680 have already handled the one case that it matters. */
15684 {
15687 }
15689 /* Compute a result for LT or EQ if args permit;
15690 Otherwise return T. */
15692 {
15695 else
15697 }
15698 else
15704 }
15706 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15707 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15708 itself. */
15710 tree
15712 {
15713 /* If the expression does not have side effects then we don't have to wrap
15714 it with a cleanup point expression. */
15718 /* If the expression is a return, check to see if the expression inside the
15719 return has no side effects or the right hand side of the modify expression
15720 inside the return. If either don't have side effects set we don't need to
15721 wrap the expression in a cleanup point expression. Note we don't check the
15722 left hand side of the modify because it should always be a return decl. */
15724 {
15731 }
15734 }
15736 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15737 of an indirection through OP0, or NULL_TREE if no simplification is
15738 possible. */
15740 tree
15742 {
15744 tree subtype;
15752 {
15755 /* *&CONST_DECL -> to the value of the const decl. */
15758 /* *&p => p; make sure to handle *&"str"[cst] here. */
15760 {
15764 else
15766 }
15767 /* *(foo *)&fooarray => fooarray[0] */
15770 && (!in_gimple_form
15772 {
15782 }
15783 /* *(foo *)&complexfoo => __real__ complexfoo */
15787 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15790 {
15794 }
15795 }
15799 {
15805 {
15806 tree op00type;
15810 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15813 {
15825 }
15826 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15829 {
15833 }
15834 /* ((foo *)&fooarray)[1] => fooarray[1] */
15837 {
15847 }
15848 }
15849 }
15851 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15854 && (!in_gimple_form
15856 {
15857 tree type_domain;
15867 NULL_TREE);
15868 }
15871 }
15873 /* Builds an expression for an indirection through T, simplifying some
15874 cases. */
15876 tree
15878 {
15886 }
15888 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15890 tree
15892 {
15897 else
15899 }
15901 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15902 whose result is ignored. The type of the returned tree need not be
15903 the same as the original expression. */
15905 tree
15907 {
15913 {
15924 else
15930 {
15946 }
15951 }
15952 }
15954 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15956 tree
15958 {
15964 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15965 have to do anything. Only do this when we are not given a const,
15966 because in that case, this check is more expensive than just
15967 doing it. */
15969 {
15974 }
15976 /* If divisor is a power of two, simplify this to bit manipulation. */
15978 {
15980 {
15994 }
15995 else
15996 {
15997 tree t;
16003 }
16004 }
16005 else
16006 {
16011 }
16014 }
16016 /* Likewise, but round down. */
16018 tree
16020 {
16027 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16028 have to do anything. Only do this when we are not given a const,
16029 because in that case, this check is more expensive than just
16030 doing it. */
16032 {
16037 }
16039 /* If divisor is a power of two, simplify this to bit manipulation. */
16041 {
16042 tree t;
16046 }
16047 else
16048 {
16053 }
16056 }
16058 /* Returns the pointer to the base of the object addressed by EXP and
16059 extracts the information about the offset of the access, storing it
16060 to PBITPOS and POFFSET. */
16062 static tree
16065 {
16066 tree core;
16067 machine_mode mode;
16069 HOST_WIDE_INT bitsize;
16073 {
16078 }
16079 else
16080 {
16084 }
16087 }
16089 /* Returns true if addresses of E1 and E2 differ by a constant, false
16090 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16092 bool
16094 {
16108 {
16118 }
16120 {
16121 /* If only one of the offsets is non-constant, the difference cannot
16122 be a constant. */
16124 }
16125 else
16130 }
16132 /* Simplify the floating point expression EXP when the sign of the
16133 result is not significant. Return NULL_TREE if no simplification
16134 is possible. */
16136 tree
16138 {
16143 {
16179 {
16182 {
16184 /* Strip copysign function call, return the 1st argument. */
16190 /* Strip sign ops from the argument of "odd" math functions. */
16192 {
16196 }
16198 }
16199 }
16204 }
16206 }