| blob | 6c65fe1c7860e8101d6ee1a0ef8885ecd283bac7 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
81 #ifndef LOAD_EXTEND_OP
82 #define LOAD_EXTEND_OP(M) UNKNOWN
83 #endif
85 /* Nonzero if we are folding constants inside an initializer; zero
86 otherwise. */
89 /* The following constants represent a bit based encoding of GCC's
90 comparison operators. This encoding simplifies transformations
91 on relational comparison operators, such as AND and OR. */
109 };
126 HOST_WIDE_INT *,
155 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
156 Otherwise, return LOC. */
158 static location_t
160 {
163 }
165 /* Similar to protected_set_expr_location, but never modify x in place,
166 if location can and needs to be set, unshare it. */
170 {
176 {
179 }
181 }
182 \f
183 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
184 division and returns the quotient. Otherwise returns
185 NULL_TREE. */
187 tree
189 {
190 widest_int quo;
197 }
198 \f
199 /* This is nonzero if we should defer warnings about undefined
200 overflow. This facility exists because these warnings are a
201 special case. The code to estimate loop iterations does not want
202 to issue any warnings, since it works with expressions which do not
203 occur in user code. Various bits of cleanup code call fold(), but
204 only use the result if it has certain characteristics (e.g., is a
205 constant); that code only wants to issue a warning if the result is
206 used. */
210 /* If a warning about undefined overflow is deferred, this is the
211 warning. Note that this may cause us to turn two warnings into
212 one, but that is fine since it is sufficient to only give one
213 warning per expression. */
217 /* If a warning about undefined overflow is deferred, this is the
218 level at which the warning should be emitted. */
222 /* Start deferring overflow warnings. We could use a stack here to
223 permit nested calls, but at present it is not necessary. */
225 void
227 {
229 }
231 /* Stop deferring overflow warnings. If there is a pending warning,
232 and ISSUE is true, then issue the warning if appropriate. STMT is
233 the statement with which the warning should be associated (used for
234 location information); STMT may be NULL. CODE is the level of the
235 warning--a warn_strict_overflow_code value. This function will use
236 the smaller of CODE and the deferred code when deciding whether to
237 issue the warning. CODE may be zero to mean to always use the
238 deferred code. */
240 void
242 {
244 location_t locus;
249 {
255 }
266 /* Use the smallest code level when deciding to issue the
267 warning. */
276 else
279 }
281 /* Stop deferring overflow warnings, ignoring any deferred
282 warnings. */
284 void
286 {
288 }
290 /* Whether we are deferring overflow warnings. */
292 bool
294 {
296 }
298 /* This is called when we fold something based on the fact that signed
299 overflow is undefined. */
301 static void
303 {
305 {
308 {
311 }
312 }
315 }
316 \f
317 /* Return true if the built-in mathematical function specified by CODE
318 is odd, i.e. -f(x) == f(-x). */
320 static bool
322 {
324 {
358 }
360 }
362 /* Check whether we may negate an integer constant T without causing
363 overflow. */
365 bool
367 {
368 tree type;
377 }
379 /* Determine whether an expression T can be cheaply negated using
380 the function negate_expr without introducing undefined overflow. */
382 static bool
384 {
385 tree type;
394 {
399 /* Check that -CST will not overflow type. */
412 /* We want to canonicalize to positive real constants. Pretend
413 that only negative ones can be easily negated. */
421 {
432 }
445 /* -(A + B) -> (-B) - A. */
450 /* -(A + B) -> (-A) - B. */
454 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
464 /* Fall through. */
475 /* In general we can't negate A / B, because if A is INT_MIN and
476 B is 1, we may turn this into INT_MIN / -1 which is undefined
477 and actually traps on some architectures. But if overflow is
478 undefined, we can negate, because - (INT_MIN / 1) is an
479 overflow. */
481 {
484 /* If overflow is undefined then we have to be careful because
485 we ask whether it's ok to associate the negate with the
486 division which is not ok for example for
487 -((a - b) / c) where (-(a - b)) / c may invoke undefined
488 overflow because of negating INT_MIN. So do not use
489 negate_expr_p here but open-code the two important cases. */
494 }
500 /* Negate -((double)float) as (double)(-float). */
502 {
506 }
510 /* Negate -f(x) as f(-x). */
516 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
518 {
522 }
527 }
529 }
531 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
532 simplification is possible.
533 If negate_expr_p would return true for T, NULL_TREE will never be
534 returned. */
536 static tree
538 {
540 tree tem;
543 {
544 /* Convert - (~A) to A + 1. */
570 {
575 }
579 {
584 {
588 }
591 }
614 {
615 /* -(A + B) -> (-B) - A. */
619 {
623 }
625 /* -(A + B) -> (-A) - B. */
627 {
631 }
632 }
636 /* - (A - B) -> B - A */
648 /* Fall through. */
652 {
661 }
667 /* In general we can't negate A / B, because if A is INT_MIN and
668 B is 1, we may turn this into INT_MIN / -1 which is undefined
669 and actually traps on some architectures. But if overflow is
670 undefined, we can negate, because - (INT_MIN / 1) is an
671 overflow. */
673 {
678 {
685 }
686 /* If overflow is undefined then we have to be careful because
687 we ask whether it's ok to associate the negate with the
688 division which is not ok for example for
689 -((a - b) / c) where (-(a - b)) / c may invoke undefined
690 overflow because of negating INT_MIN. So do not use
691 negate_expr_p here but open-code the two important cases. */
700 }
704 /* Convert -((double)float) into (double)(-float). */
706 {
710 }
714 /* Negate -f(x) as f(-x). */
717 {
723 }
727 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
729 {
732 {
739 }
740 }
745 }
748 }
750 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
751 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
752 return NULL_TREE. */
754 static tree
756 {
758 location_t loc;
771 }
772 \f
773 /* Split a tree IN into a constant, literal and variable parts that could be
774 combined with CODE to make IN. "constant" means an expression with
775 TREE_CONSTANT but that isn't an actual constant. CODE must be a
776 commutative arithmetic operation. Store the constant part into *CONP,
777 the literal in *LITP and return the variable part. If a part isn't
778 present, set it to null. If the tree does not decompose in this way,
779 return the entire tree as the variable part and the other parts as null.
781 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
782 case, we negate an operand that was subtracted. Except if it is a
783 literal for which we use *MINUS_LITP instead.
785 If NEGATE_P is true, we are negating all of IN, again except a literal
786 for which we use *MINUS_LITP instead.
788 If IN is itself a literal or constant, return it as appropriate.
790 Note that we do not guarantee that any of the three values will be the
791 same type as IN, but they will have the same signedness and mode. */
793 static tree
796 {
803 /* Strip any conversions that don't change the machine mode or signedness. */
812 /* We can associate addition and subtraction together (even
813 though the C standard doesn't say so) for integers because
814 the value is not affected. For reals, the value might be
815 affected, so we can't. */
818 {
824 /* First see if either of the operands is a literal, then a constant. */
837 /* If we haven't dealt with either operand, this is not a case we can
838 decompose. Otherwise, VAR is either of the ones remaining, if any. */
843 else
846 /* Now do any needed negations. */
853 }
856 {
857 /* -X - 1 is folded to ~X, undo that here. */
860 }
863 else
867 {
874 }
877 }
879 /* Re-associate trees split by the above function. T1 and T2 are
880 either expressions to associate or null. Return the new
881 expression, if any. LOC is the location of the new expression. If
882 we build an operation, do it in TYPE and with CODE. */
884 static tree
886 {
892 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
893 try to fold this since we will have infinite recursion. But do
894 deal with any NEGATE_EXPRs. */
897 {
899 {
912 }
914 {
917 }
921 }
925 }
926 \f
927 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
928 for use in int_const_binop, size_binop and size_diffop. */
930 static bool
932 {
939 {
948 }
953 }
956 /* Combine two integer constants ARG1 and ARG2 under operation CODE
957 to produce a new constant. Return NULL_TREE if we don't know how
958 to evaluate CODE at compile-time. */
960 static tree
963 {
964 wide_int res;
965 tree t;
974 {
990 {
994 else
996 }
999 /* It's unclear from the C standard whether shifts can overflow.
1000 The following code ignores overflow; perhaps a C standard
1001 interpretation ruling is needed. */
1003 else
1010 {
1014 else
1016 }
1020 else
1099 }
1107 }
1109 tree
1111 {
1113 }
1115 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1116 constant. We assume ARG1 and ARG2 have the same data type, or at least
1117 are the same kind of constant and the same machine mode. Return zero if
1118 combining the constants is not allowed in the current operating mode. */
1120 static tree
1122 {
1123 /* Sanity check for the recursive cases. */
1131 {
1137 }
1140 {
1141 machine_mode mode;
1142 REAL_VALUE_TYPE d1;
1143 REAL_VALUE_TYPE d2;
1144 REAL_VALUE_TYPE value;
1145 REAL_VALUE_TYPE result;
1149 /* The following codes are handled by real_arithmetic. */
1151 {
1162 }
1170 /* Don't perform operation if we honor signaling NaNs and
1171 either operand is a NaN. */
1176 /* Don't perform operation if it would raise a division
1177 by zero exception. */
1183 /* If either operand is a NaN, just return it. Otherwise, set up
1184 for floating-point trap; we return an overflow. */
1193 /* Don't constant fold this floating point operation if
1194 the result has overflowed and flag_trapping_math. */
1202 /* Don't constant fold this floating point operation if the
1203 result may dependent upon the run-time rounding mode and
1204 flag_rounding_math is set, or if GCC's software emulation
1205 is unable to accurately represent the result. */
1215 }
1218 {
1219 FIXED_VALUE_TYPE f1;
1220 FIXED_VALUE_TYPE f2;
1221 FIXED_VALUE_TYPE result;
1226 /* The following codes are handled by fixed_arithmetic. */
1228 {
1240 {
1247 }
1252 }
1259 /* Propagate overflow flags. */
1263 }
1266 {
1275 {
1286 mpc_mul);
1300 mpc_div);
1301 /* Fallthru ... */
1307 {
1308 /* Keep this algorithm in sync with
1309 tree-complex.c:expand_complex_div_straight().
1311 Expand complex division to scalars, straightforward algorithm.
1312 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1313 t = br*br + bi*bi
1314 */
1315 tree magsquared
1319 tree t1
1323 tree t2
1330 }
1331 else
1332 {
1333 /* Keep this algorithm in sync with
1334 tree-complex.c:expand_complex_div_wide().
1336 Expand complex division to scalars, modified algorithm to minimize
1337 overflow with wide input ranges. */
1343 {
1344 /* In the TRUE branch, we compute
1345 ratio = br/bi;
1346 div = (br * ratio) + bi;
1347 tr = (ar * ratio) + ai;
1348 ti = (ai * ratio) - ar;
1349 tr = tr / div;
1350 ti = ti / div; */
1361 }
1362 else
1363 {
1364 /* In the FALSE branch, we compute
1365 ratio = d/c;
1366 divisor = (d * ratio) + c;
1367 tr = (b * ratio) + a;
1368 ti = b - (a * ratio);
1369 tr = tr / div;
1370 ti = ti / div; */
1382 }
1383 }
1388 }
1392 }
1396 {
1402 {
1408 /* It is possible that const_binop cannot handle the given
1409 code and return NULL_TREE */
1412 }
1415 }
1417 /* Shifts allow a scalar offset for a vector. */
1420 {
1426 {
1431 /* It is possible that const_binop cannot handle the given
1432 code and return NULL_TREE. */
1435 }
1438 }
1440 }
1442 /* Overload that adds a TYPE parameter to be able to dispatch
1443 to fold_relational_const. */
1445 tree
1447 {
1451 /* ??? Until we make the const_binop worker take the type of the
1452 result as argument put those cases that need it here. */
1454 {
1465 {
1481 {
1487 }
1490 }
1496 {
1521 {
1534 }
1537 }
1540 }
1545 /* Make sure type and arg0 have the same saturating flag. */
1550 }
1552 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1553 Return zero if computing the constants is not possible. */
1555 tree
1557 {
1559 {
1560 CASE_CONVERT:
1575 {
1576 /* Can't call fold_negate_const directly here as that doesn't
1577 handle all cases and we might not be able to negate some
1578 constants. */
1583 }
1592 {
1596 }
1602 /* Perform BIT_NOT_EXPR on each element individually. */
1604 {
1606 tree elem;
1611 {
1617 }
1620 }
1642 {
1661 else
1665 {
1669 }
1672 }
1677 {
1691 {
1696 }
1699 {
1703 }
1706 }
1710 }
1713 }
1715 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1716 indicates which particular sizetype to create. */
1718 tree
1720 {
1722 }
1723 \f
1724 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1725 is a tree code. The type of the result is taken from the operands.
1726 Both must be equivalent integer types, ala int_binop_types_match_p.
1727 If the operands are constant, so is the result. */
1729 tree
1731 {
1740 /* Handle the special case of two integer constants faster. */
1742 {
1743 /* And some specific cases even faster than that. */
1745 {
1750 }
1752 {
1755 }
1757 {
1760 }
1762 /* Handle general case of two integer constants. For sizetype
1763 constant calculations we always want to know about overflow,
1764 even in the unsigned case. */
1766 }
1769 }
1771 /* Given two values, either both of sizetype or both of bitsizetype,
1772 compute the difference between the two values. Return the value
1773 in signed type corresponding to the type of the operands. */
1775 tree
1777 {
1779 tree ctype;
1784 /* If the type is already signed, just do the simple thing. */
1792 else
1795 /* If either operand is not a constant, do the conversions to the signed
1796 type and subtract. The hardware will do the right thing with any
1797 overflow in the subtraction. */
1803 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1804 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1805 overflow) and negate (which can't either). Special-case a result
1806 of zero while we're here. */
1812 else
1816 MINUS_EXPR,
1818 }
1819 \f
1820 /* A subroutine of fold_convert_const handling conversions of an
1821 INTEGER_CST to another integer type. */
1823 static tree
1825 {
1826 /* Given an integer constant, make new constant with new type,
1827 appropriately sign-extended or truncated. Use widest_int
1828 so that any extension is done according ARG1's type. */
1832 }
1834 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1835 to an integer type. */
1837 static tree
1839 {
1841 tree t;
1843 /* The following code implements the floating point to integer
1844 conversion rules required by the Java Language Specification,
1845 that IEEE NaNs are mapped to zero and values that overflow
1846 the target precision saturate, i.e. values greater than
1847 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1848 are mapped to INT_MIN. These semantics are allowed by the
1849 C and C++ standards that simply state that the behavior of
1850 FP-to-integer conversion is unspecified upon overflow. */
1852 wide_int val;
1853 REAL_VALUE_TYPE r;
1857 {
1864 }
1866 /* If R is NaN, return zero and show we have an overflow. */
1868 {
1871 }
1873 /* See if R is less than the lower bound or greater than the
1874 upper bound. */
1877 {
1881 {
1884 }
1885 }
1888 {
1891 {
1894 {
1897 }
1898 }
1899 }
1906 }
1908 /* A subroutine of fold_convert_const handling conversions of a
1909 FIXED_CST to an integer type. */
1911 static tree
1913 {
1914 tree t;
1918 /* Right shift FIXED_CST to temp by fbit. */
1922 {
1924 HOST_BITS_PER_DOUBLE_INT,
1927 /* Left shift temp to temp_trunc by fbit. */
1929 HOST_BITS_PER_DOUBLE_INT,
1931 }
1932 else
1933 {
1936 }
1938 /* If FIXED_CST is negative, we need to round the value toward 0.
1939 By checking if the fractional bits are not zero to add 1 to temp. */
1945 /* Given a fixed-point constant, make new constant with new type,
1946 appropriately sign-extended or truncated. */
1954 }
1956 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1957 to another floating point type. */
1959 static tree
1961 {
1962 REAL_VALUE_TYPE value;
1963 tree t;
1968 /* If converting an infinity or NAN to a representation that doesn't
1969 have one, set the overflow bit so that we can produce some kind of
1970 error message at the appropriate point if necessary. It's not the
1971 most user-friendly message, but it's better than nothing. */
1978 /* Regular overflow, conversion produced an infinity in a mode that
1979 can't represent them. */
1984 else
1987 }
1989 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1990 to a floating point type. */
1992 static tree
1994 {
1995 REAL_VALUE_TYPE value;
1996 tree t;
2003 }
2005 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2006 to another fixed-point type. */
2008 static tree
2010 {
2011 FIXED_VALUE_TYPE value;
2012 tree t;
2019 /* Propagate overflow flags. */
2023 }
2025 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2026 to a fixed-point type. */
2028 static tree
2030 {
2031 FIXED_VALUE_TYPE value;
2032 tree t;
2034 double_int di;
2041 else
2049 /* Propagate overflow flags. */
2053 }
2055 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2056 to a fixed-point type. */
2058 static tree
2060 {
2061 FIXED_VALUE_TYPE value;
2062 tree t;
2070 /* Propagate overflow flags. */
2074 }
2076 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2077 type TYPE. If no simplification can be done return NULL_TREE. */
2079 static tree
2081 {
2087 {
2094 }
2096 {
2103 }
2105 {
2112 }
2114 }
2116 /* Construct a vector of zero elements of vector type TYPE. */
2118 static tree
2120 {
2121 tree t;
2125 }
2127 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2129 bool
2131 {
2146 {
2165 }
2166 }
2168 /* Convert expression ARG to type TYPE. Used by the middle-end for
2169 simple conversions in preference to calling the front-end's convert. */
2171 tree
2173 {
2175 tree tem;
2186 {
2189 /* Handle conversions between pointers to different address spaces. */
2194 /* fall through */
2199 {
2203 }
2217 {
2221 }
2223 {
2227 }
2229 {
2233 }
2236 {
2254 }
2259 {
2263 }
2266 {
2280 }
2284 {
2293 integer_zero_node));
2295 {
2299 {
2305 }
2313 }
2317 }
2335 }
2336 fold_convert_exit:
2339 }
2340 \f
2341 /* Return false if expr can be assumed not to be an lvalue, true
2342 otherwise. */
2344 static bool
2346 {
2347 /* We only need to wrap lvalue tree codes. */
2349 {
2380 /* Assume the worst for front-end tree codes. */
2384 }
2387 }
2389 /* Return an expr equal to X but certainly not valid as an lvalue. */
2391 tree
2393 {
2394 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2395 us. */
2402 }
2404 /* When pedantic, return an expr equal to X but certainly not valid as a
2405 pedantic lvalue. Otherwise, return X. */
2407 static tree
2409 {
2411 }
2412 \f
2413 /* Given a tree comparison code, return the code that is the logical inverse.
2414 It is generally not safe to do this for floating-point comparisons, except
2415 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2416 ERROR_MARK in this case. */
2418 enum tree_code
2420 {
2426 {
2457 }
2458 }
2460 /* Similar, but return the comparison that results if the operands are
2461 swapped. This is safe for floating-point. */
2463 enum tree_code
2465 {
2467 {
2493 }
2494 }
2497 /* Convert a comparison tree code from an enum tree_code representation
2498 into a compcode bit-based encoding. This function is the inverse of
2499 compcode_to_comparison. */
2501 static enum comparison_code
2503 {
2505 {
2536 }
2537 }
2539 /* Convert a compcode bit-based encoding of a comparison operator back
2540 to GCC's enum tree_code representation. This function is the
2541 inverse of comparison_to_compcode. */
2543 static enum tree_code
2545 {
2547 {
2578 }
2579 }
2581 /* Return a tree for the comparison which is the combination of
2582 doing the AND or OR (depending on CODE) of the two operations LCODE
2583 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2584 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2585 if this makes the transformation invalid. */
2587 tree
2592 {
2599 {
2610 }
2613 {
2614 /* Eliminate unordered comparisons, as well as LTGT and ORD
2615 which are not used unless the mode has NaNs. */
2621 }
2623 {
2624 /* Check that the original operation and the optimized ones will trap
2625 under the same condition. */
2636 /* In a short-circuited boolean expression the LHS might be
2637 such that the RHS, if evaluated, will never trap. For
2638 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2639 if neither x nor y is NaN. (This is a mixed blessing: for
2640 example, the expression above will never trap, hence
2641 optimizing it to x < y would be invalid). */
2646 /* If the comparison was short-circuited, and only the RHS
2647 trapped, we may now generate a spurious trap. */
2652 /* If we changed the conditions that cause a trap, we lose. */
2655 }
2661 else
2662 {
2667 }
2668 }
2669 \f
2670 /* Return nonzero if two operands (typically of the same tree node)
2671 are necessarily equal. If either argument has side-effects this
2672 function returns zero. FLAGS modifies behavior as follows:
2674 If OEP_ONLY_CONST is set, only return nonzero for constants.
2675 This function tests whether the operands are indistinguishable;
2676 it does not test whether they are equal using C's == operation.
2677 The distinction is important for IEEE floating point, because
2678 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2679 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2681 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2682 even though it may hold multiple values during a function.
2683 This is because a GCC tree node guarantees that nothing else is
2684 executed between the evaluation of its "operands" (which may often
2685 be evaluated in arbitrary order). Hence if the operands themselves
2686 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2687 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2688 unset means assuming isochronic (or instantaneous) tree equivalence.
2689 Unless comparing arbitrary expression trees, such as from different
2690 statements, this flag can usually be left unset.
2692 If OEP_PURE_SAME is set, then pure functions with identical arguments
2693 are considered the same. It is used when the caller has other ways
2694 to ensure that global memory is unchanged in between. */
2696 int
2698 {
2699 /* If either is ERROR_MARK, they aren't equal. */
2705 /* Similar, if either does not have a type (like a released SSA name),
2706 they aren't equal. */
2710 /* Check equality of integer constants before bailing out due to
2711 precision differences. */
2715 /* If both types don't have the same signedness, then we can't consider
2716 them equal. We must check this before the STRIP_NOPS calls
2717 because they may change the signedness of the arguments. As pointers
2718 strictly don't have a signedness, require either two pointers or
2719 two non-pointers as well. */
2724 /* We cannot consider pointers to different address space equal. */
2730 /* If both types don't have the same precision, then it is not safe
2731 to strip NOPs. */
2739 /* In case both args are comparisons but with different comparison
2740 code, try to swap the comparison operands of one arg to produce
2741 a match and compare that variant. */
2745 {
2753 }
2756 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2760 /* This is needed for conversions and for COMPONENT_REF.
2761 Might as well play it safe and always test this. */
2767 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2768 We don't care about side effects in that case because the SAVE_EXPR
2769 takes care of that for us. In all other cases, two expressions are
2770 equal if they have no side effects. If we have two identical
2771 expressions with side effects that should be treated the same due
2772 to the only side effects being identical SAVE_EXPR's, that will
2773 be detected in the recursive calls below.
2774 If we are taking an invariant address of two identical objects
2775 they are necessarily equal as well. */
2782 /* Next handle constant cases, those for which we can return 1 even
2783 if ONLY_CONST is set. */
2786 {
2801 {
2802 /* If we do not distinguish between signed and unsigned zero,
2803 consider them equal. */
2806 }
2810 {
2817 {
2821 }
2823 }
2827 flags)
2829 flags));
2843 }
2848 /* Define macros to test an operand from arg0 and arg1 for equality and a
2849 variant that allows null and views null as being different from any
2850 non-null value. In the latter case, if either is null, the both
2851 must be; otherwise, do the normal comparison. */
2852 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2853 TREE_OPERAND (arg1, N), flags)
2855 #define OP_SAME_WITH_NULL(N) \
2856 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2857 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2860 {
2862 /* Two conversions are equal only if signedness and modes match. */
2864 {
2865 CASE_CONVERT:
2873 }
2883 /* For commutative ops, allow the other order. */
2891 /* If either of the pointer (or reference) expressions we are
2892 dereferencing contain a side effect, these cannot be equal,
2893 but their addresses can be. */
2900 {
2915 /* Require equal access sizes, and similar pointer types.
2916 We can have incomplete types for array references of
2917 variable-sized arrays from the Fortran frontend
2918 though. Also verify the types are compatible. */
2926 || (alias_ptr_types_compatible_p
2938 /* TARGET_MEM_REF require equal extra operands. */
2946 /* Operands 2 and 3 may be null.
2947 Compare the array index by value if it is constant first as we
2948 may have different types but same value here. */
2959 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2960 may be NULL when we're called to compare MEM_EXPRs. */
2975 }
2979 {
2997 /* The multiplcation operands are commutative. */
2998 /* FALLTHRU */
3006 /* Otherwise take into account this is a commutative operation. */
3019 }
3023 {
3027 /* If not both CALL_EXPRs are either internal or normal function
3028 functions, then they are not equal. */
3031 {
3032 /* If the CALL_EXPRs call different internal functions, then they
3033 are not equal. */
3036 }
3037 else
3038 {
3039 /* If the CALL_EXPRs call different functions, then they are not
3040 equal. */
3042 flags))
3044 }
3046 {
3050 else
3054 }
3056 /* Now see if all the arguments are the same. */
3057 {
3068 /* If we get here and both argument lists are exhausted
3069 then the CALL_EXPRs are equal. */
3071 }
3074 }
3077 /* Consider __builtin_sqrt equal to sqrt. */
3085 }
3087 #undef OP_SAME
3088 #undef OP_SAME_WITH_NULL
3089 }
3090 \f
3091 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3092 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3094 When in doubt, return 0. */
3096 static int
3098 {
3110 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3111 and see if the inner values are the same. This removes any
3112 signedness comparison, which doesn't matter here. */
3119 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3120 actual comparison operand, ARG0.
3122 First throw away any conversions to wider types
3123 already present in the operands. */
3132 {
3135 /* Make sure shorter operand is extended the right way
3136 to match the longer operand. */
3142 }
3145 }
3146 \f
3147 /* See if ARG is an expression that is either a comparison or is performing
3148 arithmetic on comparisons. The comparisons must only be comparing
3149 two different values, which will be stored in *CVAL1 and *CVAL2; if
3150 they are nonzero it means that some operands have already been found.
3151 No variables may be used anywhere else in the expression except in the
3152 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3153 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3155 If this is true, return 1. Otherwise, return zero. */
3157 static int
3159 {
3163 /* We can handle some of the tcc_expression cases here. */
3173 {
3174 /* If we've already found a CVAL1 or CVAL2, this expression is
3175 two complex to handle. */
3181 }
3184 {
3207 /* First see if we can handle the first operand, then the second. For
3208 the second operand, we know *CVAL1 can't be zero. It must be that
3209 one side of the comparison is each of the values; test for the
3210 case where this isn't true by failing if the two operands
3211 are the same. */
3220 ;
3224 ;
3225 else
3229 ;
3233 ;
3234 else
3241 }
3242 }
3243 \f
3244 /* ARG is a tree that is known to contain just arithmetic operations and
3245 comparisons. Evaluate the operations in the tree substituting NEW0 for
3246 any occurrence of OLD0 as an operand of a comparison and likewise for
3247 NEW1 and OLD1. */
3249 static tree
3252 {
3257 /* We can handle some of the tcc_expression cases here. */
3265 {
3280 {
3299 }
3300 /* Fall through - ??? */
3303 {
3307 /* We need to check both for exact equality and tree equality. The
3308 former will be true if the operand has a side-effect. In that
3309 case, we know the operand occurred exactly once. */
3322 }
3326 }
3327 }
3328 \f
3329 /* Return a tree for the case when the result of an expression is RESULT
3330 converted to TYPE and OMITTED was previously an operand of the expression
3331 but is now not needed (e.g., we folded OMITTED * 0).
3333 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3334 the conversion of RESULT to TYPE. */
3336 tree
3338 {
3341 /* If the resulting operand is an empty statement, just return the omitted
3342 statement casted to void. */
3352 }
3354 /* Return a tree for the case when the result of an expression is RESULT
3355 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3356 of the expression but are now not needed.
3358 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3359 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3360 evaluated before OMITTED2. Otherwise, if neither has side effects,
3361 just do the conversion of RESULT to TYPE. */
3363 tree
3366 {
3375 }
3377 \f
3378 /* Return a simplified tree node for the truth-negation of ARG. This
3379 never alters ARG itself. We assume that ARG is an operation that
3380 returns a truth value (0 or 1).
3382 FIXME: one would think we would fold the result, but it causes
3383 problems with the dominator optimizer. */
3385 static tree
3387 {
3392 /* If this is a comparison, we can simply invert it, except for
3393 floating-point non-equality comparisons, in which case we just
3394 enclose a TRUTH_NOT_EXPR around what we have. */
3397 {
3400 && flag_trapping_math
3411 }
3414 {
3433 /* Here we can invert either operand. We invert the first operand
3434 unless the second operand is a TRUTH_NOT_EXPR in which case our
3435 result is the XOR of the first operand with the inside of the
3436 negation of the second operand. */
3441 else
3464 {
3471 /* A COND_EXPR may have a throw as one operand, which
3472 then has void type. Just leave void operands
3473 as they are. */
3479 }
3491 CASE_CONVERT:
3495 /* ... fall through ... */
3517 }
3518 }
3520 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3521 assume that ARG is an operation that returns a truth value (0 or 1
3522 for scalars, 0 or -1 for vectors). Return the folded expression if
3523 folding is successful. Otherwise, return NULL_TREE. */
3525 static tree
3527 {
3530 ? BIT_NOT_EXPR
3533 }
3535 /* Return a simplified tree node for the truth-negation of ARG. This
3536 never alters ARG itself. We assume that ARG is an operation that
3537 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3539 tree
3541 {
3547 ? BIT_NOT_EXPR
3550 }
3552 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3553 with code CODE. This optimization is unsafe. */
3554 static tree
3557 {
3561 /* (A / C) +- (B / C) -> (A +- B) / C. */
3571 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3576 {
3588 }
3591 }
3592 \f
3593 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3594 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3596 static tree
3599 {
3603 {
3610 }
3624 }
3626 /* Optimize a bit-field compare.
3628 There are two cases: First is a compare against a constant and the
3629 second is a comparison of two items where the fields are at the same
3630 bit position relative to the start of a chunk (byte, halfword, word)
3631 large enough to contain it. In these cases we can avoid the shift
3632 implicit in bitfield extractions.
3634 For constants, we emit a compare of the shifted constant with the
3635 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3636 compared. For two fields at the same position, we do the ANDs with the
3637 similar mask and compare the result of the ANDs.
3639 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3640 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3641 are the left and right operands of the comparison, respectively.
3643 If the optimization described above can be done, we return the resulting
3644 tree. Otherwise we return zero. */
3646 static tree
3649 {
3652 tree unsigned_type;
3658 tree mask;
3659 tree offset;
3661 /* Get all the information about the extractions being done. If the bit size
3662 if the same as the size of the underlying object, we aren't doing an
3663 extraction at all and so can do nothing. We also don't want to
3664 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3665 then will no longer be able to replace it. */
3673 {
3674 /* If this is not a constant, we can only do something if bit positions,
3675 sizes, and signedness are the same. */
3683 }
3685 /* See if we can find a mode to refer to this field. We should be able to,
3686 but fail if we can't. */
3695 /* Set signed and unsigned types of the precision of this mode for the
3696 shifts below. */
3699 /* Compute the bit position and size for the new reference and our offset
3700 within it. If the new reference is the same size as the original, we
3701 won't optimize anything, so return zero. */
3711 /* Make the mask to be used against the extracted field. */
3718 /* If not comparing with constant, just rework the comparison
3719 and return. */
3723 unsigned_type,
3726 mask),
3729 unsigned_type,
3732 mask));
3734 /* Otherwise, we are handling the constant case. See if the constant is too
3735 big for the field. Warn and return a tree of for 0 (false) if so. We do
3736 this not only for its own sake, but to avoid having to test for this
3737 error case below. If we didn't, we might generate wrong code.
3739 For unsigned fields, the constant shifted right by the field length should
3740 be all zero. For signed fields, the high-order bits should agree with
3741 the sign bit. */
3744 {
3746 {
3750 }
3751 }
3752 else
3753 {
3756 {
3760 }
3761 }
3763 /* Single-bit compares should always be against zero. */
3765 {
3768 }
3770 /* Make a new bitfield reference, shift the constant over the
3771 appropriate number of bits and mask it with the computed mask
3772 (in case this was a signed field). If we changed it, make a new one. */
3779 mask);
3784 }
3785 \f
3786 /* Subroutine for fold_truth_andor_1: decode a field reference.
3788 If EXP is a comparison reference, we return the innermost reference.
3790 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3791 set to the starting bit number.
3793 If the innermost field can be completely contained in a mode-sized
3794 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3796 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3797 otherwise it is not changed.
3799 *PUNSIGNEDP is set to the signedness of the field.
3801 *PMASK is set to the mask used. This is either contained in a
3802 BIT_AND_EXPR or derived from the width of the field.
3804 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3806 Return 0 if this is not a component reference or is one that we can't
3807 do anything with. */
3809 static tree
3814 {
3818 tree unsigned_type;
3821 /* All the optimizations using this function assume integer fields.
3822 There are problems with FP fields since the type_for_size call
3823 below can fail for, e.g., XFmode. */
3827 /* We are interested in the bare arrangement of bits, so strip everything
3828 that doesn't affect the machine mode. However, record the type of the
3829 outermost expression if it may matter below. */
3836 {
3842 }
3851 /* If the number of bits in the reference is the same as the bitsize of
3852 the outer type, then the outer type gives the signedness. Otherwise
3853 (in case of a small bitfield) the signedness is unchanged. */
3857 /* Compute the mask to access the bitfield. */
3866 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3874 }
3876 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3877 bit positions and MASK is SIGNED. */
3879 static int
3881 {
3885 /* If this function returns true when the type of the mask is
3886 UNSIGNED, then there will be errors. In particular see
3887 gcc.c-torture/execute/990326-1.c. There does not appear to be
3888 any documentation paper trail as to why this is so. But the pre
3889 wide-int worked with that restriction and it has been preserved
3890 here. */
3895 }
3897 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3898 represents the sign bit of EXP's type. If EXP represents a sign
3899 or zero extension, also test VAL against the unextended type.
3900 The return value is the (sub)expression whose sign bit is VAL,
3901 or NULL_TREE otherwise. */
3903 tree
3905 {
3907 tree t;
3909 /* Tree EXP must have an integral type. */
3914 /* Tree VAL must be an integer constant. */
3923 /* Handle extension from a narrower type. */
3929 }
3931 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3932 to be evaluated unconditionally. */
3934 static int
3936 {
3937 /* Strip any conversions that don't change the machine mode. */
3946 /* Don't regard global variables as simple. They may be
3947 allocated in ways unknown to the compiler (shared memory,
3948 #pragma weak, etc). */
3951 /* Weakrefs are not safe to be read, since they can be NULL.
3952 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3953 have DECL_WEAK flag set. */
3955 /* Loading a static variable is unduly expensive, but global
3956 registers aren't expensive. */
3958 }
3960 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3961 to be evaluated unconditionally.
3962 I addition to simple_operand_p, we assume that comparisons, conversions,
3963 and logic-not operations are simple, if their operands are simple, too. */
3965 static bool
3967 {
3987 }
3989 \f
3990 /* The following functions are subroutines to fold_range_test and allow it to
3991 try to change a logical combination of comparisons into a range test.
3993 For example, both
3994 X == 2 || X == 3 || X == 4 || X == 5
3995 and
3996 X >= 2 && X <= 5
3997 are converted to
3998 (unsigned) (X - 2) <= 3
4000 We describe each set of comparisons as being either inside or outside
4001 a range, using a variable named like IN_P, and then describe the
4002 range with a lower and upper bound. If one of the bounds is omitted,
4003 it represents either the highest or lowest value of the type.
4005 In the comments below, we represent a range by two numbers in brackets
4006 preceded by a "+" to designate being inside that range, or a "-" to
4007 designate being outside that range, so the condition can be inverted by
4008 flipping the prefix. An omitted bound is represented by a "-". For
4009 example, "- [-, 10]" means being outside the range starting at the lowest
4010 possible value and ending at 10, in other words, being greater than 10.
4011 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4012 always false.
4014 We set up things so that the missing bounds are handled in a consistent
4015 manner so neither a missing bound nor "true" and "false" need to be
4016 handled using a special case. */
4018 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4019 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4020 and UPPER1_P are nonzero if the respective argument is an upper bound
4021 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4022 must be specified for a comparison. ARG1 will be converted to ARG0's
4023 type if both are specified. */
4025 static tree
4028 {
4029 tree tem;
4033 /* If neither arg represents infinity, do the normal operation.
4034 Else, if not a comparison, return infinity. Else handle the special
4035 comparison rules. Note that most of the cases below won't occur, but
4036 are handled for consistency. */
4039 {
4044 }
4049 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4050 for neither. In real maths, we cannot assume open ended ranges are
4051 the same. But, this is computer arithmetic, where numbers are finite.
4052 We can therefore make the transformation of any unbounded range with
4053 the value Z, Z being greater than any representable number. This permits
4054 us to treat unbounded ranges as equal. */
4058 {
4079 }
4082 }
4083 \f
4084 /* Helper routine for make_range. Perform one step for it, return
4085 new expression if the loop should continue or NULL_TREE if it should
4086 stop. */
4088 tree
4092 {
4098 {
4100 /* We can only do something if the range is testing for zero. */
4109 /* We can only do something if the range is testing for zero
4110 and if the second operand is an integer constant. Note that
4111 saying something is "in" the range we make is done by
4112 complementing IN_P since it will set in the initial case of
4113 being not equal to zero; "out" is leaving it alone. */
4120 {
4141 }
4143 /* If this is an unsigned comparison, we also know that EXP is
4144 greater than or equal to zero. We base the range tests we make
4145 on that fact, so we record it here so we can parse existing
4146 range tests. We test arg0_type since often the return type
4147 of, e.g. EQ_EXPR, is boolean. */
4149 {
4153 NULL_TREE))
4158 /* If the high bound is missing, but we have a nonzero low
4159 bound, reverse the range so it goes from zero to the low bound
4160 minus 1. */
4162 {
4167 }
4168 }
4176 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4177 low and high are non-NULL, then normalize will DTRT. */
4180 {
4185 }
4187 /* (-x) IN [a,b] -> x in [-b, -a] */
4199 /* ~ X -> -X - 1 */
4208 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4209 move a constant to the other side. */
4214 /* If EXP is signed, any overflow in the computation is undefined,
4215 so we don't worry about it so long as our computations on
4216 the bounds don't overflow. For unsigned, overflow is defined
4217 and this is exactly the right thing. */
4229 normalize:
4230 /* Check for an unsigned range which has wrapped around the maximum
4231 value thus making n_high < n_low, and normalize it. */
4233 {
4239 /* If the range is of the form +/- [ x+1, x ], we won't
4240 be able to normalize it. But then, it represents the
4241 whole range or the empty set, so make it
4242 +/- [ -, - ]. */
4246 else
4248 }
4249 else
4257 CASE_CONVERT:
4275 /* If we're converting arg0 from an unsigned type, to exp,
4276 a signed type, we will be doing the comparison as unsigned.
4277 The tests above have already verified that LOW and HIGH
4278 are both positive.
4280 So we have to ensure that we will handle large unsigned
4281 values the same way that the current signed bounds treat
4282 negative values. */
4285 {
4286 tree high_positive;
4287 tree equiv_type;
4288 /* For fixed-point modes, we need to pass the saturating flag
4289 as the 2nd parameter. */
4291 equiv_type
4294 else
4295 equiv_type
4298 /* A range without an upper bound is, naturally, unbounded.
4299 Since convert would have cropped a very large value, use
4300 the max value for the destination type. */
4301 high_positive
4308 high_positive),
4311 /* If the low bound is specified, "and" the range with the
4312 range for which the original unsigned value will be
4313 positive. */
4315 {
4318 integer_zero_node),
4319 high_positive))
4323 }
4324 else
4325 {
4326 /* Otherwise, "or" the range with the range of the input
4327 that will be interpreted as negative. */
4330 integer_zero_node),
4331 high_positive))
4335 }
4336 }
4345 }
4346 }
4348 /* Given EXP, a logical expression, set the range it is testing into
4349 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4350 actually being tested. *PLOW and *PHIGH will be made of the same
4351 type as the returned expression. If EXP is not a comparison, we
4352 will most likely not be returning a useful value and range. Set
4353 *STRICT_OVERFLOW_P to true if the return value is only valid
4354 because signed overflow is undefined; otherwise, do not change
4355 *STRICT_OVERFLOW_P. */
4357 tree
4360 {
4368 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4369 and see if we can refine the range. Some of the cases below may not
4370 happen, but it doesn't seem worth worrying about this. We "continue"
4371 the outer loop when we've changed something; otherwise we "break"
4372 the switch, which will "break" the while. */
4378 {
4384 {
4392 }
4401 }
4403 /* If EXP is a constant, we can evaluate whether this is true or false. */
4405 {
4412 }
4416 }
4417 \f
4418 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4419 type, TYPE, return an expression to test if EXP is in (or out of, depending
4420 on IN_P) the range. Return 0 if the test couldn't be created. */
4422 tree
4425 {
4428 /* Disable this optimization for function pointer expressions
4429 on targets that require function pointer canonicalization. */
4436 {
4442 }
4460 {
4462 {
4466 }
4468 }
4470 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4472 {
4476 {
4478 {
4481 etype
4483 else
4486 }
4489 }
4490 }
4492 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4493 This requires wrap-around arithmetics for the type of the expression.
4494 First make sure that arithmetics in this type is valid, then make sure
4495 that it wraps around. */
4501 {
4504 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4505 for the type in question, as we rely on this here. */
4515 else
4517 }
4527 {
4529 {
4534 }
4536 }
4544 }
4545 \f
4546 /* Return the predecessor of VAL in its type, handling the infinite case. */
4548 static tree
4550 {
4556 else
4559 }
4561 /* Return the successor of VAL in its type, handling the infinite case. */
4563 static tree
4565 {
4571 else
4574 }
4576 /* Given two ranges, see if we can merge them into one. Return 1 if we
4577 can, 0 if we can't. Set the output range into the specified parameters. */
4579 bool
4582 {
4586 tree tem;
4596 /* Make range 0 be the range that starts first, or ends last if they
4597 start at the same value. Swap them if it isn't. */
4600 || (lowequal
4603 {
4607 }
4609 /* Now flag two cases, whether the ranges are disjoint or whether the
4610 second range is totally subsumed in the first. Note that the tests
4611 below are simplified by the ones above. */
4617 /* We now have four cases, depending on whether we are including or
4618 excluding the two ranges. */
4620 {
4621 /* If they don't overlap, the result is false. If the second range
4622 is a subset it is the result. Otherwise, the range is from the start
4623 of the second to the end of the first. */
4628 else
4630 }
4633 {
4634 /* If they don't overlap, the result is the first range. If they are
4635 equal, the result is false. If the second range is a subset of the
4636 first, and the ranges begin at the same place, we go from just after
4637 the end of the second range to the end of the first. If the second
4638 range is not a subset of the first, or if it is a subset and both
4639 ranges end at the same place, the range starts at the start of the
4640 first range and ends just before the second range.
4641 Otherwise, we can't describe this as a single range. */
4647 {
4652 {
4653 /* We are in the weird situation where high0 > high1 but
4654 high1 has no successor. Punt. */
4656 }
4657 }
4659 {
4664 {
4665 /* low0 < low1 but low1 has no predecessor. Punt. */
4667 }
4668 }
4669 else
4671 }
4674 {
4675 /* If they don't overlap, the result is the second range. If the second
4676 is a subset of the first, the result is false. Otherwise,
4677 the range starts just after the first range and ends at the
4678 end of the second. */
4683 else
4684 {
4689 {
4690 /* high1 > high0 but high0 has no successor. Punt. */
4692 }
4693 }
4694 }
4696 else
4697 {
4698 /* The case where we are excluding both ranges. Here the complex case
4699 is if they don't overlap. In that case, the only time we have a
4700 range is if they are adjacent. If the second is a subset of the
4701 first, the result is the first. Otherwise, the range to exclude
4702 starts at the beginning of the first range and ends at the end of the
4703 second. */
4705 {
4710 else
4711 {
4712 /* Canonicalize - [min, x] into - [-, x]. */
4715 {
4720 /* FALLTHROUGH */
4733 }
4735 /* Canonicalize - [x, max] into - [x, -]. */
4738 {
4743 /* FALLTHROUGH */
4759 }
4761 /* The ranges might be also adjacent between the maximum and
4762 minimum values of the given type. For
4763 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4764 return + [x + 1, y - 1]. */
4766 {
4773 }
4774 else
4776 }
4777 }
4780 else
4782 }
4786 }
4787 \f
4789 /* Subroutine of fold, looking inside expressions of the form
4790 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4791 of the COND_EXPR. This function is being used also to optimize
4792 A op B ? C : A, by reversing the comparison first.
4794 Return a folded expression whose code is not a COND_EXPR
4795 anymore, or NULL_TREE if no folding opportunity is found. */
4797 static tree
4800 {
4805 tree tem;
4810 /* If we have A op 0 ? A : -A, consider applying the following
4811 transformations:
4813 A == 0? A : -A same as -A
4814 A != 0? A : -A same as A
4815 A >= 0? A : -A same as abs (A)
4816 A > 0? A : -A same as abs (A)
4817 A <= 0? A : -A same as -abs (A)
4818 A < 0? A : -A same as -abs (A)
4820 None of these transformations work for modes with signed
4821 zeros. If A is +/-0, the first two transformations will
4822 change the sign of the result (from +0 to -0, or vice
4823 versa). The last four will fix the sign of the result,
4824 even though the original expressions could be positive or
4825 negative, depending on the sign of A.
4827 Note that all these transformations are correct if A is
4828 NaN, since the two alternatives (A and -A) are also NaNs. */
4835 /* In the case that A is of the form X-Y, '-A' (arg2) may
4836 have already been folded to Y-X, check for that. */
4844 {
4858 /* Fall through. */
4880 }
4882 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4883 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4884 both transformations are correct when A is NaN: A != 0
4885 is then true, and A == 0 is false. */
4889 {
4894 }
4896 /* Try some transformations of A op B ? A : B.
4898 A == B? A : B same as B
4899 A != B? A : B same as A
4900 A >= B? A : B same as max (A, B)
4901 A > B? A : B same as max (B, A)
4902 A <= B? A : B same as min (A, B)
4903 A < B? A : B same as min (B, A)
4905 As above, these transformations don't work in the presence
4906 of signed zeros. For example, if A and B are zeros of
4907 opposite sign, the first two transformations will change
4908 the sign of the result. In the last four, the original
4909 expressions give different results for (A=+0, B=-0) and
4910 (A=-0, B=+0), but the transformed expressions do not.
4912 The first two transformations are correct if either A or B
4913 is a NaN. In the first transformation, the condition will
4914 be false, and B will indeed be chosen. In the case of the
4915 second transformation, the condition A != B will be true,
4916 and A will be chosen.
4918 The conversions to max() and min() are not correct if B is
4919 a number and A is not. The conditions in the original
4920 expressions will be false, so all four give B. The min()
4921 and max() versions would give a NaN instead. */
4924 /* Avoid these transformations if the COND_EXPR may be used
4925 as an lvalue in the C++ front-end. PR c++/19199. */
4926 && (in_gimple_form
4932 {
4937 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4939 {
4943 }
4946 {
4955 /* In C++ a ?: expression can be an lvalue, so put the
4956 operand which will be used if they are equal first
4957 so that we can convert this back to the
4958 corresponding COND_EXPR. */
4960 {
4969 }
4976 {
4985 }
5000 }
5001 }
5003 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5004 we might still be able to simplify this. For example,
5005 if C1 is one less or one more than C2, this might have started
5006 out as a MIN or MAX and been transformed by this function.
5007 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5013 {
5017 /* We can replace A with C1 in this case. */
5022 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5023 MIN_EXPR, to preserve the signedness of the comparison. */
5025 OEP_ONLY_CONST)
5029 OEP_ONLY_CONST))
5030 {
5033 arg2));
5036 }
5040 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5041 as above. */
5043 OEP_ONLY_CONST)
5047 OEP_ONLY_CONST))
5048 {
5051 arg2));
5054 }
5058 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5059 MAX_EXPR, to preserve the signedness of the comparison. */
5061 OEP_ONLY_CONST)
5065 OEP_ONLY_CONST))
5066 {
5069 arg2));
5071 }
5075 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5077 OEP_ONLY_CONST)
5081 OEP_ONLY_CONST))
5082 {
5085 arg2));
5087 }
5093 }
5096 }
5099 \f
5100 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5101 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5102 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5103 false) >= 2)
5104 #endif
5106 /* EXP is some logical combination of boolean tests. See if we can
5107 merge it into some range test. Return the new tree if so. */
5109 static tree
5112 {
5128 /* If this is an OR operation, invert both sides; we will invert
5129 again at the end. */
5133 /* If both expressions are the same, if we can merge the ranges, and we
5134 can build the range test, return it or it inverted. If one of the
5135 ranges is always true or always false, consider it to be the same
5136 expression as the other. */
5144 {
5148 }
5150 /* On machines where the branch cost is expensive, if this is a
5151 short-circuited branch and the underlying object on both sides
5152 is the same, make a non-short-circuit operation. */
5158 {
5159 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5160 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5161 which cases we can't do this. */
5169 {
5178 {
5181 WARN_STRICT_OVERFLOW_COMPARISON);
5185 }
5186 }
5187 }
5190 }
5191 \f
5192 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5193 bit value. Arrange things so the extra bits will be set to zero if and
5194 only if C is signed-extended to its full width. If MASK is nonzero,
5195 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5197 static tree
5199 {
5202 tree temp;
5207 /* We work by getting just the sign bit into the low-order bit, then
5208 into the high-order bit, then sign-extend. We then XOR that value
5209 with C. */
5212 /* We must use a signed type in order to get an arithmetic right shift.
5213 However, we must also avoid introducing accidental overflows, so that
5214 a subsequent call to integer_zerop will work. Hence we must
5215 do the type conversion here. At this point, the constant is either
5216 zero or one, and the conversion to a signed type can never overflow.
5217 We could get an overflow if this conversion is done anywhere else. */
5226 /* If necessary, convert the type back to match the type of C. */
5231 }
5232 \f
5233 /* For an expression that has the form
5234 (A && B) || ~B
5235 or
5236 (A || B) && ~B,
5237 we can drop one of the inner expressions and simplify to
5238 A || ~B
5239 or
5240 A && ~B
5241 LOC is the location of the resulting expression. OP is the inner
5242 logical operation; the left-hand side in the examples above, while CMPOP
5243 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5244 removing a condition that guards another, as in
5245 (A != NULL && A->...) || A == NULL
5246 which we must not transform. If RHS_ONLY is true, only eliminate the
5247 right-most operand of the inner logical operation. */
5249 static tree
5252 {
5270 {
5273 {
5276 }
5277 }
5279 {
5282 {
5285 }
5286 }
5301 }
5303 /* Find ways of folding logical expressions of LHS and RHS:
5304 Try to merge two comparisons to the same innermost item.
5305 Look for range tests like "ch >= '0' && ch <= '9'".
5306 Look for combinations of simple terms on machines with expensive branches
5307 and evaluate the RHS unconditionally.
5309 For example, if we have p->a == 2 && p->b == 4 and we can make an
5310 object large enough to span both A and B, we can do this with a comparison
5311 against the object ANDed with the a mask.
5313 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5314 operations to do this with one comparison.
5316 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5317 function and the one above.
5319 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5320 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5322 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5323 two operands.
5325 We return the simplified tree or 0 if no optimization is possible. */
5327 static tree
5330 {
5331 /* If this is the "or" of two comparisons, we can do something if
5332 the comparisons are NE_EXPR. If this is the "and", we can do something
5333 if the comparisons are EQ_EXPR. I.e.,
5334 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5336 WANTED_CODE is this operation code. For single bit fields, we can
5337 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5338 comparison for one-bit fields. */
5358 /* Start by getting the comparison codes. Fail if anything is volatile.
5359 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5360 it were surrounded with a NE_EXPR. */
5369 {
5373 }
5376 {
5380 }
5391 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5394 {
5397 {
5402 }
5405 {
5411 }
5412 }
5417 /* If the RHS can be evaluated unconditionally and its operands are
5418 simple, it wins to evaluate the RHS unconditionally on machines
5419 with expensive branches. In this case, this isn't a comparison
5420 that can be merged. */
5427 {
5428 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5439 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5449 }
5451 /* See if the comparisons can be merged. Then get all the parameters for
5452 each side. */
5476 /* It must be true that the inner operation on the lhs of each
5477 comparison must be the same if we are to be able to do anything.
5478 Then see if we have constants. If not, the same must be true for
5479 the rhs's. */
5490 else
5493 /* If either comparison code is not correct for our logical operation,
5494 fail. However, we can convert a one-bit comparison against zero into
5495 the opposite comparison against that bit being set in the field. */
5499 {
5501 {
5502 /* Make the left operand unsigned, since we are only interested
5503 in the value of one bit. Otherwise we are doing the wrong
5504 thing below. */
5507 }
5508 else
5510 }
5512 /* This is analogous to the code for l_const above. */
5514 {
5516 {
5519 }
5520 else
5522 }
5524 /* See if we can find a mode that contains both fields being compared on
5525 the left. If we can't, fail. Otherwise, update all constants and masks
5526 to be relative to a field of that size. */
5531 volatilep);
5541 {
5544 }
5552 {
5559 {
5563 }
5564 }
5566 {
5573 {
5577 }
5578 }
5580 /* If the right sides are not constant, do the same for it. Also,
5581 disallow this optimization if a size or signedness mismatch occurs
5582 between the left and right sides. */
5584 {
5587 /* Make sure the two fields on the right
5588 correspond to the left without being swapped. */
5596 volatilep);
5606 {
5609 }
5618 /* Make a mask that corresponds to both fields being compared.
5619 Do this for both items being compared. If the operands are the
5620 same size and the bits being compared are in the same position
5621 then we can do this by masking both and comparing the masked
5622 results. */
5626 {
5638 }
5640 /* There is still another way we can do something: If both pairs of
5641 fields being compared are adjacent, we may be able to make a wider
5642 field containing them both.
5644 Note that we still must mask the lhs/rhs expressions. Furthermore,
5645 the mask must be shifted to account for the shift done by
5646 make_bit_field_ref. */
5651 {
5652 tree type;
5666 /* Convert to the smaller type before masking out unwanted bits. */
5669 {
5671 {
5675 }
5677 {
5681 }
5682 }
5691 }
5694 }
5696 /* Handle the case of comparisons with constants. If there is something in
5697 common between the masks, those bits of the constants must be the same.
5698 If not, the condition is always false. Test for this to avoid generating
5699 incorrect code below. */
5704 {
5706 {
5709 }
5710 else
5711 {
5714 }
5715 }
5717 /* Construct the expression we will return. First get the component
5718 reference we will make. Unless the mask is all ones the width of
5719 that field, perform the mask operation. Then compare with the
5720 merged constant. */
5730 }
5731 \f
5732 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5733 constant. */
5735 static tree
5738 {
5741 tree comp_const;
5742 tree minmax_const;
5744 tree inner;
5755 /* If something does not permit us to optimize, return the original tree. */
5763 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5764 and GT_EXPR, doing the rest with recursive calls using logical
5765 simplifications. */
5767 {
5769 {
5770 tree tem
5777 }
5780 return
5782 optimize_minmax_comparison
5784 optimize_minmax_comparison
5789 /* MAX (X, 0) == 0 -> X <= 0 */
5793 /* MAX (X, 0) == 5 -> X == 5 */
5797 /* MAX (X, 0) == -1 -> false */
5801 /* MIN (X, 0) == 0 -> X >= 0 */
5805 /* MIN (X, 0) == 5 -> false */
5808 else
5809 /* MIN (X, 0) == -1 -> X == -1 */
5814 /* MAX (X, 0) > 0 -> X > 0
5815 MAX (X, 0) > 5 -> X > 5 */
5819 /* MAX (X, 0) > -1 -> true */
5823 /* MIN (X, 0) > 0 -> false
5824 MIN (X, 0) > 5 -> false */
5827 else
5828 /* MIN (X, 0) > -1 -> X > -1 */
5833 }
5834 }
5835 \f
5836 /* T is an integer expression that is being multiplied, divided, or taken a
5837 modulus (CODE says which and what kind of divide or modulus) by a
5838 constant C. See if we can eliminate that operation by folding it with
5839 other operations already in T. WIDE_TYPE, if non-null, is a type that
5840 should be used for the computation if wider than our type.
5842 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5843 (X * 2) + (Y * 4). We must, however, be assured that either the original
5844 expression would not overflow or that overflow is undefined for the type
5845 in the language in question.
5847 If we return a non-null expression, it is an equivalent form of the
5848 original computation, but need not be in the original type.
5850 We set *STRICT_OVERFLOW_P to true if the return values depends on
5851 signed overflow being undefined. Otherwise we do not change
5852 *STRICT_OVERFLOW_P. */
5854 static tree
5857 {
5858 /* To avoid exponential search depth, refuse to allow recursion past
5859 three levels. Beyond that (1) it's highly unlikely that we'll find
5860 something interesting and (2) we've probably processed it before
5861 when we built the inner expression. */
5864 tree ret;
5869 depth++;
5871 depth--;
5874 }
5876 static tree
5879 {
5890 /* Don't deal with constants of zero here; they confuse the code below. */
5900 /* Note that we need not handle conditional operations here since fold
5901 already handles those cases. So just do arithmetic here. */
5903 {
5905 /* For a constant, we can always simplify if we are a multiply
5906 or (for divide and modulus) if it is a multiple of our constant. */
5914 /* If op0 is an expression ... */
5920 /* ... and has wrapping overflow, and its type is smaller
5921 than ctype, then we cannot pass through as widening. */
5926 /* ... or this is a truncation (t is narrower than op0),
5927 then we cannot pass through this narrowing. */
5930 /* ... or signedness changes for division or modulus,
5931 then we cannot pass through this conversion. */
5935 /* ... or has undefined overflow while the converted to
5936 type has not, we cannot do the operation in the inner type
5937 as that would introduce undefined overflow. */
5943 /* Pass the constant down and see if we can make a simplification. If
5944 we can, replace this expression with the inner simplification for
5945 possible later conversion to our or some other type. */
5950 code == MULT_EXPR
5952 strict_overflow_p))))
5957 /* If widening the type changes it from signed to unsigned, then we
5958 must avoid building ABS_EXPR itself as unsigned. */
5960 {
5964 {
5967 }
5969 }
5970 /* If the constant is negative, we cannot simplify this. */
5973 /* FALLTHROUGH */
5975 /* For division and modulus, type can't be unsigned, as e.g.
5976 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
5977 For signed types, even with wrapping overflow, this is fine. */
5986 /* If widening the type changes the signedness, then we can't perform
5987 this optimization as that changes the result. */
5991 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5997 {
6004 }
6008 /* If the second operand is constant, this is a multiplication
6009 or floor division, by a power of two, so we can treat it that
6010 way unless the multiplier or divisor overflows. Signed
6011 left-shift overflow is implementation-defined rather than
6012 undefined in C90, so do not convert signed left shift into
6013 multiplication. */
6016 /* const_binop may not detect overflow correctly,
6017 so check for it explicitly here. */
6021 size_one_node,
6022 op1)))
6026 ctype,
6028 t1),
6033 /* See if we can eliminate the operation on both sides. If we can, we
6034 can return a new PLUS or MINUS. If we can't, the only remaining
6035 cases where we can do anything are if the second operand is a
6036 constant. */
6042 /* If not multiplication, we can only do this if both operands
6043 are divisible by c. */
6046 {
6051 }
6053 /* If this was a subtraction, negate OP1 and set it to be an addition.
6054 This simplifies the logic below. */
6056 {
6058 /* If OP1 was not easily negatable, the constant may be OP0. */
6060 {
6063 }
6064 }
6069 /* If either OP1 or C are negative, this optimization is not safe for
6070 some of the division and remainder types while for others we need
6071 to change the code. */
6073 {
6081 }
6083 /* If it's a multiply or a division/modulus operation of a multiple
6084 of our constant, do the operation and verify it doesn't overflow. */
6087 {
6090 /* We allow the constant to overflow with wrapping semantics. */
6094 }
6095 else
6098 /* If we have an unsigned type, we cannot widen the operation since it
6099 will change the result if the original computation overflowed. */
6103 /* If we were able to eliminate our operation from the first side,
6104 apply our operation to the second side and reform the PLUS. */
6108 /* The last case is if we are a multiply. In that case, we can
6109 apply the distributive law to commute the multiply and addition
6110 if the multiplication of the constants doesn't overflow
6111 and overflow is defined. With undefined overflow
6112 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6118 op1);
6123 /* We have a special case here if we are doing something like
6124 (C * 8) % 4 since we know that's zero. */
6127 /* If the multiplication can overflow we cannot optimize this. */
6131 {
6134 }
6136 /* ... fall through ... */
6140 /* If we can extract our operation from the LHS, do so and return a
6141 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6142 do something only if the second operand is a constant. */
6156 /* If these are the same operation types, we can associate them
6157 assuming no overflow. */
6159 {
6171 }
6173 /* If these operations "cancel" each other, we have the main
6174 optimizations of this pass, which occur when either constant is a
6175 multiple of the other, in which case we replace this with either an
6176 operation or CODE or TCODE.
6178 If we have an unsigned type, we cannot do this since it will change
6179 the result if the original computation overflowed. */
6186 {
6188 {
6195 }
6197 {
6204 }
6205 }
6210 }
6213 }
6214 \f
6215 /* Return a node which has the indicated constant VALUE (either 0 or
6216 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6217 and is of the indicated TYPE. */
6219 tree
6221 {
6230 else
6232 }
6235 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6236 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6237 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6238 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6239 COND is the first argument to CODE; otherwise (as in the example
6240 given here), it is the second argument. TYPE is the type of the
6241 original expression. Return NULL_TREE if no simplification is
6242 possible. */
6244 static tree
6249 {
6259 {
6263 /* If this operand throws an expression, then it does not make
6264 sense to try to perform a logical or arithmetic operation
6265 involving it. */
6270 }
6271 else
6272 {
6277 }
6282 /* This transformation is only worthwhile if we don't have to wrap ARG
6283 in a SAVE_EXPR and the operation can be simplified without recursing
6284 on at least one of the branches once its pushed inside the COND_EXPR. */
6293 {
6297 else
6299 }
6301 {
6305 else
6307 }
6309 /* Check that we have simplified at least one of the branches. */
6314 }
6316 \f
6317 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6319 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6320 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6321 ADDEND is the same as X.
6323 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6324 and finite. The problematic cases are when X is zero, and its mode
6325 has signed zeros. In the case of rounding towards -infinity,
6326 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6327 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6329 bool
6331 {
6335 /* Don't allow the fold with -fsignaling-nans. */
6339 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6343 /* In a vector or complex, we would need to check the sign of all zeros. */
6347 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6351 /* The mode has signed zeros, and we have to honor their sign.
6352 In this situation, there is only one case we can return true for.
6353 X - 0 is the same as X unless rounding towards -infinity is
6354 supported. */
6356 }
6358 /* Subroutine of fold() that optimizes comparisons of a division by
6359 a nonzero integer constant against an integer constant, i.e.
6360 X/C1 op C2.
6362 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6363 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6364 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6366 The function returns the constant folded tree if a simplification
6367 can be made, and NULL_TREE otherwise. */
6369 static tree
6372 {
6380 /* We have to do this the hard way to detect unsigned overflow.
6381 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6387 {
6392 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6396 }
6398 {
6402 {
6421 }
6422 }
6423 else
6424 {
6425 /* A negative divisor reverses the relational operators. */
6431 {
6450 }
6451 }
6454 {
6475 {
6478 }
6483 {
6486 }
6491 {
6494 }
6499 {
6502 }
6507 }
6510 }
6513 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6514 equality/inequality test, then return a simplified form of the test
6515 using a sign testing. Otherwise return NULL. TYPE is the desired
6516 result type. */
6518 static tree
6521 tree result_type)
6522 {
6523 /* If this is testing a single bit, we can optimize the test. */
6527 {
6528 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6529 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6533 /* This is only a win if casting to a signed type is cheap,
6534 i.e. when arg00's type is not a partial mode. */
6537 {
6540 result_type,
6543 }
6544 }
6547 }
6549 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6550 equality/inequality test, then return a simplified form of
6551 the test using shifts and logical operations. Otherwise return
6552 NULL. TYPE is the desired result type. */
6554 tree
6557 {
6558 /* If this is testing a single bit, we can optimize the test. */
6562 {
6571 /* First, see if we can fold the single bit test into a sign-bit
6572 test. */
6574 result_type);
6578 /* Otherwise we have (A & C) != 0 where C is a single bit,
6579 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6580 Similarly for (A & C) == 0. */
6582 /* If INNER is a right shift of a constant and it plus BITNUM does
6583 not overflow, adjust BITNUM and INNER. */
6589 {
6592 }
6594 /* If we are going to be able to omit the AND below, we must do our
6595 operations as unsigned. If we must use the AND, we have a choice.
6596 Normally unsigned is faster, but for some machines signed is. */
6614 /* Put the AND last so it can combine with more things. */
6617 /* Make sure to return the proper type. */
6621 }
6623 }
6625 /* Check whether we are allowed to reorder operands arg0 and arg1,
6626 such that the evaluation of arg1 occurs before arg0. */
6628 static bool
6630 {
6637 }
6639 /* Test whether it is preferable two swap two operands, ARG0 and
6640 ARG1, for example because ARG0 is an integer constant and ARG1
6641 isn't. If REORDER is true, only recommend swapping if we can
6642 evaluate the operands in reverse order. */
6644 bool
6646 {
6664 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6665 for commutative and comparison operators. Ensuring a canonical
6666 form allows the optimizers to find additional redundancies without
6667 having to explicitly check for both orderings. */
6673 /* Put SSA_NAMEs last. */
6679 /* Put variables last. */
6686 }
6689 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6690 means A >= Y && A != MAX, but in this case we know that
6691 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6693 static tree
6695 {
6702 else
6711 {
6714 }
6716 {
6719 }
6720 else
6727 {
6728 /* Convert the pointer types into integer before taking the difference. */
6732 }
6733 else
6740 }
6742 /* Fold a sum or difference of at least one multiplication.
6743 Returns the folded tree or NULL if no simplification could be made. */
6745 static tree
6748 {
6752 /* (A * C) +- (B * C) -> (A+-B) * C.
6753 (A * C) +- A -> A * (C+-1).
6754 We are most concerned about the case where C is a constant,
6755 but other combinations show up during loop reduction. Since
6756 it is not difficult, try all four possibilities. */
6759 {
6762 }
6764 {
6767 }
6768 else
6769 {
6770 /* We cannot generate constant 1 for fract. */
6775 }
6777 {
6780 }
6782 {
6784 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6785 the purpose of this canonicalization. */
6789 {
6792 }
6793 else
6795 }
6796 else
6797 {
6798 /* We cannot generate constant 1 for fract. */
6803 }
6815 /* No identical multiplicands; see if we can find a common
6816 power-of-two factor in non-power-of-two multiplies. This
6817 can help in multi-dimensional array access. */
6820 {
6823 tree maybe_same;
6827 /* Move min of absolute values to int11. */
6829 {
6834 }
6835 else
6839 /* The remainder should not be a constant, otherwise we
6840 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6841 increased the number of multiplications necessary. */
6843 {
6851 }
6852 }
6862 }
6864 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6865 specified by EXPR into the buffer PTR of length LEN bytes.
6866 Return the number of bytes placed in the buffer, or zero
6867 upon failure. */
6869 static int
6871 {
6885 {
6887 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
6888 number of bytes. */
6892 {
6899 else
6901 }
6902 else
6907 }
6909 }
6912 /* Subroutine of native_encode_expr. Encode the FIXED_CST
6913 specified by EXPR into the buffer PTR of length LEN bytes.
6914 Return the number of bytes placed in the buffer, or zero
6915 upon failure. */
6917 static int
6919 {
6923 FIXED_VALUE_TYPE value;
6939 }
6942 /* Subroutine of native_encode_expr. Encode the REAL_CST
6943 specified by EXPR into the buffer PTR of length LEN bytes.
6944 Return the number of bytes placed in the buffer, or zero
6945 upon failure. */
6947 static int
6949 {
6955 /* There are always 32 bits in each long, no matter the size of
6956 the hosts long. We handle floating point representations with
6957 up to 192 bits. */
6971 {
6976 {
6983 else
6985 }
6986 else
6992 }
6994 }
6996 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
6997 specified by EXPR into the buffer PTR of length LEN bytes.
6998 Return the number of bytes placed in the buffer, or zero
6999 upon failure. */
7001 static int
7003 {
7005 tree part;
7020 }
7023 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7024 specified by EXPR into the buffer PTR of length LEN bytes.
7025 Return the number of bytes placed in the buffer, or zero
7026 upon failure. */
7028 static int
7030 {
7040 {
7042 {
7045 }
7056 }
7058 }
7061 /* Subroutine of native_encode_expr. Encode the STRING_CST
7062 specified by EXPR into the buffer PTR of length LEN bytes.
7063 Return the number of bytes placed in the buffer, or zero
7064 upon failure. */
7066 static int
7068 {
7070 HOST_WIDE_INT total_bytes;
7084 {
7087 {
7090 }
7093 }
7094 else
7097 }
7100 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7101 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7102 buffer PTR of length LEN bytes. If OFF is not -1 then start
7103 the encoding at byte offset OFF and encode at most LEN bytes.
7104 Return the number of bytes placed in the buffer, or zero upon failure. */
7106 int
7108 {
7110 {
7131 }
7132 }
7135 /* Subroutine of native_interpret_expr. Interpret the contents of
7136 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7137 If the buffer cannot be interpreted, return NULL_TREE. */
7139 static tree
7141 {
7151 }
7154 /* Subroutine of native_interpret_expr. Interpret the contents of
7155 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7156 If the buffer cannot be interpreted, return NULL_TREE. */
7158 static tree
7160 {
7162 double_int result;
7163 FIXED_VALUE_TYPE fixed_value;
7173 }
7176 /* Subroutine of native_interpret_expr. Interpret the contents of
7177 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7178 If the buffer cannot be interpreted, return NULL_TREE. */
7180 static tree
7182 {
7187 /* There are always 32 bits in each long, no matter the size of
7188 the hosts long. We handle floating point representations with
7189 up to 192 bits. */
7190 REAL_VALUE_TYPE r;
7201 {
7204 {
7211 else
7213 }
7214 else
7219 }
7223 }
7226 /* Subroutine of native_interpret_expr. Interpret the contents of
7227 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7228 If the buffer cannot be interpreted, return NULL_TREE. */
7230 static tree
7232 {
7247 }
7250 /* Subroutine of native_interpret_expr. Interpret the contents of
7251 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7252 If the buffer cannot be interpreted, return NULL_TREE. */
7254 static tree
7256 {
7269 {
7274 }
7276 }
7279 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7280 the buffer PTR of length LEN as a constant of type TYPE. For
7281 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7282 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7283 return NULL_TREE. */
7285 tree
7287 {
7289 {
7311 }
7312 }
7314 /* Returns true if we can interpret the contents of a native encoding
7315 as TYPE. */
7317 static bool
7319 {
7321 {
7334 }
7335 }
7337 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7338 TYPE at compile-time. If we're unable to perform the conversion
7339 return NULL_TREE. */
7341 static tree
7343 {
7344 /* We support up to 512-bit values (for V8DFmode). */
7348 /* Check that the host and target are sane. */
7357 }
7359 /* Build an expression for the address of T. Folds away INDIRECT_REF
7360 to avoid confusing the gimplify process. */
7362 tree
7364 {
7365 /* The size of the object is not relevant when talking about its address. */
7370 {
7375 }
7385 {
7390 }
7391 else
7395 }
7397 /* Build an expression for the address of T. */
7399 tree
7401 {
7405 }
7407 /* Fold a unary expression of code CODE and type TYPE with operand
7408 OP0. Return the folded expression if folding is successful.
7409 Otherwise, return NULL_TREE. */
7411 tree
7413 {
7414 tree tem;
7415 tree arg0;
7423 {
7426 {
7427 /* Don't use STRIP_NOPS, because signedness of argument type
7428 matters. */
7430 }
7431 else
7432 {
7433 /* Strip any conversions that don't change the mode. This
7434 is safe for every expression, except for a comparison
7435 expression because its signedness is derived from its
7436 operands.
7438 Note that this is done as an internal manipulation within
7439 the constant folder, in order to find the simplest
7440 representation of the arguments so that their form can be
7441 studied. In any cases, the appropriate type conversions
7442 should be put back in the tree that will get out of the
7443 constant folder. */
7445 }
7448 {
7451 {
7455 }
7456 }
7457 }
7464 {
7471 {
7485 /* If this was a conversion, and all we did was to move into
7486 inside the COND_EXPR, bring it back out. But leave it if
7487 it is a conversion from integer to integer and the
7488 result precision is no wider than a word since such a
7489 conversion is cheap and may be optimized away by combine,
7490 while it couldn't if it were outside the COND_EXPR. Then return
7491 so we don't get into an infinite recursion loop taking the
7492 conversion out and then back in. */
7504 && (INTEGRAL_TYPE_P
7517 }
7518 }
7521 {
7527 CASE_CONVERT:
7531 {
7532 /* If we have (type) (a CMP b) and type is an integral type, return
7533 new expression involving the new type. Canonicalize
7534 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7535 non-integral type.
7536 Do not fold the result as that would not simplify further, also
7537 folding again results in recursions. */
7547 }
7549 /* Handle (T *)&A.B.C for A being of type T and B and C
7550 living at offset zero. This occurs frequently in
7551 C++ upcasting and then accessing the base. */
7555 {
7557 tree offset;
7558 machine_mode mode;
7563 /* If the reference was to a (constant) zero offset, we can use
7564 the address of the base if it has the same base type
7565 as the result type and the pointer type is unqualified. */
7572 }
7576 /* Detect assigning a bitfield. */
7578 && DECL_BIT_FIELD
7580 {
7581 /* Don't leave an assignment inside a conversion
7582 unless assigning a bitfield. */
7584 /* First do the assignment, then return converted constant. */
7589 }
7591 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7592 constants (if x has signed type, the sign bit cannot be set
7593 in c). This folds extension into the BIT_AND_EXPR.
7594 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7595 very likely don't have maximal range for their precision and this
7596 transformation effectively doesn't preserve non-maximal ranges. */
7600 {
7611 <= HOST_BITS_PER_WIDE_INT
7613 {
7617 cst &= HOST_WIDE_INT_M1U
7621 && !flag_syntax_only
7624 {
7628 }
7629 }
7631 {
7636 }
7637 }
7639 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7640 when one of the new casts will fold away. Conservatively we assume
7641 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7648 {
7652 return fold_build_pointer_plus_loc
7654 }
7656 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7657 of the same precision, and X is an integer type not narrower than
7658 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7664 {
7670 }
7672 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7673 type of X and Y (integer types only). */
7678 {
7679 /* Be careful not to introduce new overflows. */
7680 tree mult_type;
7683 else
7687 {
7694 }
7695 }
7713 /* Convert fabs((double)float) into (double)fabsf(float). */
7716 {
7722 targ0));
7723 }
7725 /* Strip sign ops from argument. */
7727 {
7732 }
7739 {
7745 }
7751 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7770 /* Note that the operand of this must be an int
7771 and its values must be 0 or 1.
7772 ("true" is a fixed value perhaps depending on the language,
7773 but we don't handle values other than 1 correctly yet.) */
7783 {
7791 }
7793 {
7798 }
7800 {
7804 {
7813 }
7814 }
7821 {
7829 }
7831 {
7835 }
7837 {
7841 {
7850 }
7851 }
7855 /* Fold *&X to X if X is an lvalue. */
7857 {
7864 }
7870 }
7873 /* If the operation was a conversion do _not_ mark a resulting constant
7874 with TREE_OVERFLOW if the original constant was not. These conversions
7875 have implementation defined behavior and retaining the TREE_OVERFLOW
7876 flag here would confuse later passes such as VRP. */
7877 tree
7880 {
7889 }
7891 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7892 operands OP0 and OP1. LOC is the location of the resulting expression.
7893 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7894 Return the folded expression if folding is successful. Otherwise,
7895 return NULL_TREE. */
7896 static tree
7899 {
7900 tree tem;
7902 /* We only do these simplifications if we are optimizing. */
7906 /* Check for things like (A || B) && (A || C). We can convert this
7907 to A || (B && C). Note that either operator can be any of the four
7908 truth and/or operations and the transformation will still be
7909 valid. Also note that we only care about order for the
7910 ANDIF and ORIF operators. If B contains side effects, this
7911 might change the truth-value of A. */
7918 {
7938 /* This case if tricky because we must either have commutative
7939 operators or else A10 must not have side-effects. */
7945 a01);
7946 }
7948 /* See if we can build a range comparison. */
7954 {
7958 }
7962 {
7966 }
7968 /* Check for the possibility of merging component references. If our
7969 lhs is another similar operation, try to merge its rhs with our
7970 rhs. Then try to merge our lhs and rhs. */
7984 {
7991 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
7992 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
7993 We don't want to pack more than two leafs to a non-IF AND/OR
7994 expression.
7995 If tree-code of left-hand operand isn't an AND/OR-IF code and not
7996 equal to IF-CODE, then we don't want to add right-hand operand.
7997 If the inner right-hand side of left-hand operand has
7998 side-effects, or isn't simple, then we can't add to it,
7999 as otherwise we might destroy if-sequence. */
8002 /* Needed for sequence points to handle trappings, and
8003 side-effects. */
8005 {
8007 arg1);
8009 tem);
8010 }
8011 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8012 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8015 /* Needed for sequence points to handle trappings, and
8016 side-effects. */
8018 {
8023 }
8024 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8025 into (A OR B).
8026 For sequence point consistancy, we need to check for trapping,
8027 and side-effects. */
8031 }
8034 }
8036 /* Fold a binary expression of code CODE and type TYPE with operands
8037 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8038 Return the folded expression if folding is successful. Otherwise,
8039 return NULL_TREE. */
8041 static tree
8043 {
8050 else
8053 /* MIN (MAX (a, b), b) == b. */
8058 /* MIN (MAX (b, a), b) == b. */
8064 /* MIN (a, MAX (a, b)) == a. */
8070 /* MIN (a, MAX (b, a)) == a. */
8077 }
8079 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8080 by changing CODE to reduce the magnitude of constants involved in
8081 ARG0 of the comparison.
8082 Returns a canonicalized comparison tree if a simplification was
8083 possible, otherwise returns NULL_TREE.
8084 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8085 valid if signed overflow is undefined. */
8087 static tree
8091 {
8096 /* Match A +- CST code arg1. We can change this only if overflow
8097 is undefined. */
8100 /* In principle pointers also have undefined overflow behavior,
8101 but that causes problems elsewhere. */
8108 /* Identify the constant in arg0 and its sign. */
8112 /* Overflowed constants and zero will cause problems. */
8117 /* See if we can reduce the magnitude of the constant in
8118 arg0 by changing the comparison code. */
8119 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8123 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8127 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8131 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8135 else
8139 /* Now build the constant reduced in magnitude. But not if that
8140 would produce one outside of its types range. */
8156 }
8158 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8159 overflow further. Try to decrease the magnitude of constants involved
8160 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8161 and put sole constants at the second argument position.
8162 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8164 static tree
8167 {
8168 tree t;
8173 /* Try canonicalization by simplifying arg0. */
8178 {
8182 }
8184 /* Try canonicalization by simplifying arg1 using the swapped
8185 comparison. */
8193 }
8195 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8196 space. This is used to avoid issuing overflow warnings for
8197 expressions like &p->x which can not wrap. */
8199 static bool
8201 {
8208 wide_int wi_offset;
8214 else
8230 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8231 array. */
8233 {
8234 HOST_WIDE_INT base_size;
8239 }
8242 }
8244 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8245 kind INTEGER_CST. This makes sure to properly sign-extend the
8246 constant. */
8248 static HOST_WIDE_INT
8250 {
8256 }
8258 /* Subroutine of fold_binary. This routine performs all of the
8259 transformations that are common to the equality/inequality
8260 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8261 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8262 fold_binary should call fold_binary. Fold a comparison with
8263 tree code CODE and type TYPE with operands OP0 and OP1. Return
8264 the folded comparison or NULL_TREE. */
8266 static tree
8269 {
8279 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8281 && (equality_code
8288 {
8289 const enum tree_code
8296 /* If the constant operation overflowed this can be
8297 simplified as a comparison against INT_MAX/INT_MIN. */
8300 {
8304 /* Get the sign of the constant on the lhs if the
8305 operation were VARIABLE + CONST1. */
8309 /* The sign of the constant determines if we overflowed
8310 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8311 Canonicalize to the INT_MIN overflow by swapping the comparison
8312 if necessary. */
8316 /* We now can look at the canonicalized case
8317 VARIABLE + 1 CODE2 INT_MIN
8318 and decide on the result. */
8320 {
8324 return
8330 return
8335 }
8336 }
8337 else
8338 {
8341 "when changing X +- C1 cmp C2 to "
8343 WARN_STRICT_OVERFLOW_COMPARISON);
8345 }
8346 }
8348 /* For comparisons of pointers we can decompose it to a compile time
8349 comparison of the base objects and the offsets into the object.
8350 This requires at least one operand being an ADDR_EXPR or a
8351 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8357 {
8360 machine_mode mode;
8364 /* Get base and offset for the access. Strip ADDR_EXPR for
8365 get_inner_reference, but put it back by stripping INDIRECT_REF
8366 off the base object if possible. indirect_baseN will be true
8367 if baseN is not an address but refers to the object itself. */
8370 {
8376 else
8378 }
8380 {
8384 {
8387 }
8390 {
8395 {
8398 }
8399 }
8400 }
8404 {
8410 else
8412 }
8414 {
8418 {
8421 }
8424 {
8429 {
8432 }
8433 }
8434 }
8436 /* If we have equivalent bases we might be able to simplify. */
8439 {
8440 /* We can fold this expression to a constant if the non-constant
8441 offset parts are equal. */
8450 {
8456 "occur when comparing P +- C1 with "
8458 WARN_STRICT_OVERFLOW_CONDITIONAL);
8461 {
8475 }
8476 }
8477 /* We can simplify the comparison to a comparison of the variable
8478 offset parts if the constant offset parts are equal.
8479 Be careful to use signed sizetype here because otherwise we
8480 mess with array offsets in the wrong way. This is possible
8481 because pointer arithmetic is restricted to retain within an
8482 object and overflow on pointer differences is undefined as of
8483 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8485 && (equality_code
8488 {
8489 /* By converting to signed sizetype we cover middle-end pointer
8490 arithmetic which operates on unsigned pointer types of size
8491 type size and ARRAY_REF offsets which are properly sign or
8492 zero extended from their type in case it is narrower than
8493 sizetype. */
8496 else
8500 else
8507 "occur when comparing P +- C1 with "
8509 WARN_STRICT_OVERFLOW_COMPARISON);
8512 }
8513 }
8514 /* For equal offsets we can simplify to a comparison of the
8515 base addresses. */
8517 && (indirect_base0
8519 && (indirect_base1
8524 {
8530 }
8531 }
8533 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8534 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8535 the resulting offset is smaller in absolute value than the
8536 original one and has the same sign. */
8545 {
8550 tree cst;
8552 "occur when combining constants around "
8555 /* Put the constant on the side where it doesn't overflow and is
8556 of lower absolute value and of same sign than before. */
8563 {
8566 variable1,
8570 }
8578 {
8584 variable2);
8585 }
8586 }
8592 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8593 constant, we can simplify it. */
8598 {
8602 }
8604 /* If we are comparing an expression that just has comparisons
8605 of two integer values, arithmetic expressions of those comparisons,
8606 and constants, we can simplify it. There are only three cases
8607 to check: the two values can either be equal, the first can be
8608 greater, or the second can be greater. Fold the expression for
8609 those three values. Since each value must be 0 or 1, we have
8610 eight possibilities, each of which corresponds to the constant 0
8611 or 1 or one of the six possible comparisons.
8613 This handles common cases like (a > b) == 0 but also handles
8614 expressions like ((x > y) - (y > x)) > 0, which supposedly
8615 occur in macroized code. */
8618 {
8623 /* Don't handle degenerate cases here; they should already
8624 have been handled anyway. */
8633 {
8637 /* We can't just pass T to eval_subst in case cval1 or cval2
8638 was the same as ARG1. */
8640 tree high_result
8644 arg1);
8645 tree equal_result
8649 arg1);
8650 tree low_result
8654 arg1);
8656 /* All three of these results should be 0 or 1. Confirm they are.
8657 Then use those values to select the proper code to use. */
8662 {
8663 /* Make a 3-bit mask with the high-order bit being the
8664 value for `>', the next for '=', and the low for '<'. */
8668 {
8670 /* Always false. */
8691 /* Always true. */
8693 }
8696 {
8700 }
8702 }
8703 }
8704 }
8706 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8707 into a single range test. */
8715 {
8719 }
8722 }
8725 /* Subroutine of fold_binary. Optimize complex multiplications of the
8726 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8727 argument EXPR represents the expression "z" of type TYPE. */
8729 static tree
8731 {
8736 {
8739 }
8741 {
8744 }
8745 else
8746 {
8750 }
8759 }
8762 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8763 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8765 static bool
8767 {
8771 {
8774 }
8776 {
8782 else
8784 }
8785 else
8791 }
8793 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8794 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8795 NULL_TREE otherwise. */
8797 static tree
8799 {
8816 {
8820 }
8823 {
8829 }
8830 else
8832 }
8834 /* Try to fold a pointer difference of type TYPE two address expressions of
8835 array references AREF0 and AREF1 using location LOC. Return a
8836 simplified expression for the difference or NULL_TREE. */
8838 static tree
8841 {
8846 /* If the bases are array references as well, recurse. If the bases
8847 are pointer indirections compute the difference of the pointers.
8848 If the bases are equal, we are set. */
8851 && (base_offset
8859 {
8865 base_offset,
8868 }
8870 }
8872 /* If the real or vector real constant CST of type TYPE has an exact
8873 inverse, return it, else return NULL. */
8875 tree
8877 {
8878 REAL_VALUE_TYPE r;
8880 machine_mode mode;
8884 {
8900 {
8905 }
8911 }
8912 }
8914 /* Mask out the tz least significant bits of X of type TYPE where
8915 tz is the number of trailing zeroes in Y. */
8916 static wide_int
8918 {
8923 }
8925 /* Return true when T is an address and is known to be nonzero.
8926 For floating point we further ensure that T is not denormal.
8927 Similar logic is present in nonzero_address in rtlanal.h.
8929 If the return value is based on the assumption that signed overflow
8930 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8931 change *STRICT_OVERFLOW_P. */
8933 static bool
8935 {
8939 /* Doing something useful for floating point would need more work. */
8945 {
8948 strict_overflow_p);
8954 strict_overflow_p);
8962 }
8965 {
8968 strict_overflow_p);
8976 strict_overflow_p);
8991 strict_overflow_p);
8995 strict_overflow_p);
8998 {
9010 }
9014 }
9016 }
9018 /* Return true when T is an address and is known to be nonzero.
9019 Handle warnings about undefined signed overflow. */
9021 static bool
9023 {
9030 "determining that expression is always "
9032 WARN_STRICT_OVERFLOW_MISC);
9034 }
9036 /* Fold a binary expression of code CODE and type TYPE with operands
9037 OP0 and OP1. LOC is the location of the resulting expression.
9038 Return the folded expression if folding is successful. Otherwise,
9039 return NULL_TREE. */
9041 tree
9044 {
9059 /* Strip any conversions that don't change the mode. This is
9060 safe for every expression, except for a comparison expression
9061 because its signedness is derived from its operands. So, in
9062 the latter case, only strip conversions that don't change the
9063 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9064 preserved.
9066 Note that this is done as an internal manipulation within the
9067 constant folder, in order to find the simplest representation
9068 of the arguments so that their form can be studied. In any
9069 cases, the appropriate type conversions should be put back in
9070 the tree that will get out of the constant folder. */
9073 {
9076 }
9077 else
9078 {
9081 }
9083 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9084 constant but we can't do arithmetic on them. */
9086 {
9089 {
9093 }
9094 }
9096 /* If this is a commutative operation, and ARG0 is a constant, move it
9097 to ARG1 to reduce the number of tests below. */
9102 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9103 to ARG1 to reduce the number of tests below. */
9112 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9114 First check for cases where an arithmetic operation is applied to a
9115 compound, conditional, or comparison operation. Push the arithmetic
9116 operation inside the compound or conditional to see if any folding
9117 can then be done. Convert comparison to conditional for this purpose.
9118 The also optimizes non-constant cases that used to be done in
9119 expand_expr.
9121 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9122 one of the operands is a comparison and the other is a comparison, a
9123 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9124 code below would make the expression more complex. Change it to a
9125 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9126 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9139 {
9143 boolean_type_node,
9151 }
9155 {
9157 {
9162 tem);
9163 }
9166 {
9171 tem);
9172 }
9177 {
9183 }
9188 {
9194 }
9195 }
9198 {
9200 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9203 {
9209 }
9211 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9214 {
9215 tree base;
9216 HOST_WIDE_INT coffset;
9225 }
9230 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9236 arg1),
9238 arg0)));
9244 {
9245 /* X + (X / CST) * -CST is X % CST. */
9250 {
9259 cst0));
9260 }
9261 }
9263 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9264 one. Make sure the type is not saturating and has the signedness of
9265 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9266 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9273 {
9277 }
9280 {
9281 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9282 (plus (plus (mult) (mult)) (foo)) so that we can
9283 take advantage of the factoring cases below. */
9292 {
9298 else
9311 parg0),
9313 marg)),
9317 return
9323 parg1)));
9324 }
9325 }
9326 else
9327 {
9328 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9329 to __complex__ ( x, y ). This is not the same for SNaNs or
9330 if signed zeros are involved. */
9334 {
9341 {
9345 {
9351 }
9353 {
9359 }
9360 }
9361 }
9369 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9370 We associate floats only if the user has specified
9371 -fassociative-math. */
9375 {
9380 {
9381 tree tree0;
9384 }
9385 }
9386 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9387 We associate floats only if the user has specified
9388 -fassociative-math. */
9392 {
9397 {
9398 tree tree0;
9401 }
9402 }
9403 }
9405 bit_rotate:
9406 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9407 is a rotate of A by C1 bits. */
9408 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9409 is a rotate of A by B bits. */
9410 {
9412 tree rtype;
9421 /* Only create rotates in complete modes. Other cases are not
9422 expanded properly. */
9425 {
9439 {
9443 code0 == LSHIFT_EXPR
9447 }
9449 {
9457 element_precision
9461 return
9464 ? LROTATE_EXPR
9469 }
9471 {
9479 element_precision
9483 return fold_convert_loc
9486 ? LROTATE_EXPR
9490 }
9491 }
9492 }
9494 associate:
9495 /* In most languages, can't associate operations on floats through
9496 parentheses. Rather than remember where the parentheses were, we
9497 don't associate floats at all, unless the user has specified
9498 -fassociative-math.
9499 And, we need to make sure type is not saturating. */
9503 {
9509 /* Split both trees into variables, constants, and literals. Then
9510 associate each group together, the constants with literals,
9511 then the result with variables. This increases the chances of
9512 literals being recombined later and of generating relocatable
9513 expressions for the sum of a constant and literal. */
9518 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9522 /* With undefined overflow prefer doing association in a type
9523 which wraps on overflow, if that is one of the operand types. */
9526 {
9534 }
9536 /* With undefined overflow we can only associate constants with one
9537 variable, and constants whose association doesn't overflow. */
9540 {
9542 {
9560 /* The only case we can still associate with two variables
9561 is if they are the same, modulo negation and bit-pattern
9562 preserving conversions. */
9565 }
9566 }
9568 /* Only do something if we found more than two objects. Otherwise,
9569 nothing has changed and we risk infinite recursion. */
9575 {
9587 /* Preserve the MINUS_EXPR if the negative part of the literal is
9588 greater than the positive part. Otherwise, the multiplicative
9589 folding code (i.e extract_muldiv) may be fooled in case
9590 unsigned constants are subtracted, like in the following
9591 example: ((X*2 + 4) - 8U)/2. */
9593 {
9597 {
9601 }
9602 else
9603 {
9607 }
9608 }
9610 /* Don't introduce overflows through reassociation. */
9617 {
9619 return
9623 else
9624 {
9627 return
9631 }
9632 }
9635 return
9638 }
9639 }
9644 /* Pointer simplifications for subtraction, simple reassociations. */
9646 {
9647 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
9650 {
9660 }
9661 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
9663 {
9670 }
9671 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
9672 simplifies. */
9674 {
9681 arg10);
9684 }
9685 }
9686 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9697 {
9698 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9699 any power of 2 minus 1. */
9704 {
9710 {
9714 }
9715 }
9716 }
9718 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9719 __complex__ ( x, -y ). This is not the same for SNaNs or if
9720 signed zeros are involved. */
9724 {
9731 {
9735 {
9737 arg1r ? arg1r
9742 }
9744 {
9748 arg1i ? arg1i
9751 }
9752 }
9753 }
9755 /* A - B -> A + (-B) if B is easily negatable. */
9759 /* Avoid this transformation if B is a positive REAL_CST. */
9768 /* Fold &a[i] - &a[j] to i-j. */
9773 {
9779 }
9782 && flag_unsafe_math_optimizations
9788 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9789 one. Make sure the type is not saturating and has the signedness of
9790 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9791 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9798 {
9802 }
9807 /* (-A) * (-B) -> A * B */
9822 {
9823 /* Transform x * -C into -x * C if x is easily negatable. */
9832 tem);
9834 /* (a * (1 << b)) is (a << b) */
9844 /* (A + A) * C -> A * 2 * C */
9856 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9857 sign-changing only. */
9867 {
9870 "occur when simplifying "
9872 WARN_STRICT_OVERFLOW_MISC);
9874 }
9876 /* Optimize z * conj(z) for integer complex numbers. */
9883 }
9884 else
9885 {
9886 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
9887 the result for floating point types due to rounding so it is applied
9888 only if -fassociative-math was specify. */
9893 {
9895 arg1);
9899 }
9901 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9903 {
9906 {
9909 }
9910 }
9912 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9913 This is not the same for NaNs or if signed zeros are
9914 involved. */
9920 {
9923 return
9929 return
9934 }
9936 /* Optimize z * conj(z) for floating point complex numbers.
9937 Guarded by flag_unsafe_math_optimizations as non-finite
9938 imaginary components don't produce scalar results. */
9949 {
9953 /* Optimizations of root(...)*root(...). */
9955 {
9960 /* Optimize sqrt(x)*sqrt(x) as x. */
9966 /* Optimize root(x)*root(y) as root(x*y). */
9970 }
9972 /* Optimize expN(x)*expN(y) as expN(x+y). */
9974 {
9980 }
9982 /* Optimizations of pow(...)*pow(...). */
9986 {
9992 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9994 {
9999 }
10001 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10003 {
10008 }
10009 }
10011 /* Optimize tan(x)*cos(x) as sin(x). */
10020 {
10026 }
10028 /* Optimize x*pow(x,c) as pow(x,c+1). */
10032 {
10038 {
10040 REAL_VALUE_TYPE c;
10041 tree arg;
10047 }
10048 }
10050 /* Optimize pow(x,c)*x as pow(x,c+1). */
10054 {
10060 {
10062 REAL_VALUE_TYPE c;
10063 tree arg;
10069 }
10070 }
10072 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10074 && optimize
10076 {
10080 {
10083 }
10084 }
10085 }
10086 }
10090 /* Canonicalize (X & C1) | C2. */
10094 {
10099 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10107 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10112 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10113 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10114 mode which allows further optimizations. */
10119 {
10123 {
10126 }
10127 }
10134 c3)),
10135 arg1);
10136 }
10138 /* (X & ~Y) | (~X & Y) is X ^ Y */
10141 {
10158 }
10160 /* See if this can be simplified into a rotate first. If that
10161 is unsuccessful continue in the association code. */
10165 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10173 /* See if this can be simplified into a rotate first. If that
10174 is unsuccessful continue in the association code. */
10178 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
10186 /* X & ~X , X & (X == 0), and X & !X are always zero. */
10194 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10199 {
10200 tree tem2;
10207 }
10208 /* Fold ~X & 1 as (X & 1) == 0. */
10212 {
10213 tree tem2;
10220 }
10221 /* Fold !X & 1 as X == 0. */
10224 {
10228 }
10230 /* Fold (X ^ Y) & Y as ~X & Y. */
10233 {
10238 }
10239 /* Fold (X ^ Y) & X as ~Y & X. */
10243 {
10248 }
10249 /* Fold X & (X ^ Y) as X & ~Y. */
10252 {
10257 }
10258 /* Fold X & (Y ^ X) as ~Y & X. */
10262 {
10267 }
10269 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10270 multiple of 1 << CST. */
10272 {
10279 }
10281 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10282 bits from CST2. */
10286 {
10294 {
10295 /* Avoid the transform if arg1 is a mask of some
10296 mode which allows further optimizations. */
10303 }
10304 }
10306 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10307 ((A & N) + B) & M -> (A + B) & M
10308 Similarly if (N & M) == 0,
10309 ((A | N) + B) & M -> (A + B) & M
10310 and for - instead of + (or unary - instead of +)
10311 and/or ^ instead of |.
10312 If B is constant and (B & M) == 0, fold into A & M. */
10314 {
10323 {
10326 wide_int cst0;
10328 /* Now we know that arg0 is (C + D) or (C - D) or
10329 -C and arg1 (M) is == (1LL << cst) - 1.
10330 Store C into PMOP[0] and D into PMOP[1]. */
10334 {
10337 }
10344 {
10354 {
10357 }
10360 /* If C or D is of the form (A & N) where
10361 (N & M) == M, or of the form (A | N) or
10362 (A ^ N) where (N & M) == 0, replace it with A. */
10366 /* If C or D is a N where (N & M) == 0, it can be
10367 omitted (assumed 0). */
10375 }
10377 /* Only build anything new if we optimized one or both arguments
10378 above. */
10382 {
10385 {
10386 /* Perform the operations in a type that has defined
10387 overflow behavior. */
10393 }
10398 {
10406 else
10408 }
10411 else
10414 /* TEM is now the new binary +, - or unary - replacement. */
10418 }
10419 }
10420 }
10422 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10425 {
10430 return
10432 }
10437 /* Don't touch a floating-point divide by zero unless the mode
10438 of the constant can represent infinity. */
10444 /* (-A) / (-B) -> A / B */
10454 /* Convert A/B/C to A/(B*C). */
10461 /* Convert A/(B/C) to (A/B)*C. */
10469 /* Convert C1/(X*C2) into (C1/C2)/X. */
10474 {
10480 }
10483 {
10487 /* Optimize sin(x)/cos(x) as tan(x). */
10493 {
10498 }
10500 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10506 {
10510 {
10515 }
10516 }
10518 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10519 NaNs or Infinities. */
10523 {
10530 {
10535 }
10536 }
10538 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10539 NaNs or Infinities. */
10543 {
10550 {
10554 {
10558 tmp);
10559 }
10560 }
10561 }
10563 /* Optimize pow(x,c)/x as pow(x,c-1). */
10567 {
10573 {
10575 REAL_VALUE_TYPE c;
10576 tree arg;
10582 }
10583 }
10585 /* Optimize a/root(b/c) into a*root(c/b). */
10587 {
10591 {
10600 }
10601 }
10603 /* Optimize x/expN(y) into x*expN(-y). */
10605 {
10612 }
10614 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10618 {
10626 }
10627 }
10631 /* Optimize (X & (-A)) / A where A is a power of 2,
10632 to X >> log2(A) */
10636 {
10644 }
10645 }
10647 /* Fall through */
10650 /* Simplify A / (B << N) where A and B are positive and B is
10651 a power of 2, to A >> (N + log2(B)). */
10656 {
10659 {
10667 WARN_STRICT_OVERFLOW_MISC);
10673 }
10674 }
10676 /* Fall through */
10684 /* Convert -A / -B to A / B when the type is signed and overflow is
10685 undefined. */
10689 {
10692 "when distributing negation across "
10694 WARN_STRICT_OVERFLOW_MISC);
10700 }
10704 {
10707 "when distributing negation across "
10709 WARN_STRICT_OVERFLOW_MISC);
10715 }
10717 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10718 operation, EXACT_DIV_EXPR.
10720 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10721 At one time others generated faster code, it's not clear if they do
10722 after the last round to changes to the DIV code in expmed.c. */
10733 {
10737 WARN_STRICT_OVERFLOW_MISC);
10739 }
10751 {
10755 WARN_STRICT_OVERFLOW_MISC);
10757 }
10765 /* Since negative shift count is not well-defined,
10766 don't try to compute it in the compiler. */
10772 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10773 into x & ((unsigned)-1 >> c) for unsigned types. */
10781 {
10784 tree lshift;
10785 tree arg00;
10788 {
10795 }
10796 }
10798 /* If we have a rotate of a bit operation with the rotate count and
10799 the second operand of the bit operation both constant,
10800 permute the two operations. */
10812 /* Two consecutive rotates adding up to the some integer
10813 multiple of the precision of the type can be ignored. */
10836 /* Note that the operands of this must be ints
10837 and their values must be 0 or 1.
10838 ("true" is a fixed value perhaps depending on the language.) */
10839 /* If first arg is constant zero, return it. */
10843 /* If either arg is constant true, drop it. */
10847 /* Preserve sequence points. */
10850 /* If second arg is constant zero, result is zero, but first arg
10851 must be evaluated. */
10854 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10855 case will be handled here. */
10859 /* !X && X is always false. */
10863 /* X && !X is always false. */
10868 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10869 means A >= Y && A != MAX, but in this case we know that
10870 A < X <= MAX. */
10874 {
10882 }
10891 /* Note that the operands of this must be ints
10892 and their values must be 0 or true.
10893 ("true" is a fixed value perhaps depending on the language.) */
10894 /* If first arg is constant true, return it. */
10898 /* If either arg is constant zero, drop it. */
10902 /* Preserve sequence points. */
10905 /* If second arg is constant true, result is true, but we must
10906 evaluate first arg. */
10909 /* Likewise for first arg, but note this only occurs here for
10910 TRUTH_OR_EXPR. */
10914 /* !X || X is always true. */
10918 /* X || !X is always true. */
10923 /* (X && !Y) || (!X && Y) is X ^ Y */
10926 {
10943 }
10952 /* If the second arg is constant zero, drop it. */
10955 /* If the second arg is constant true, this is a logical inversion. */
10957 {
10960 }
10961 /* Identical arguments cancel to zero. */
10965 /* !X ^ X is always true. */
10970 /* X ^ !X is always true. */
10986 /* bool_var != 1 becomes !bool_var. */
10993 /* bool_var == 0 becomes !bool_var. */
11000 /* !exp != 0 becomes !exp */
11005 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
11014 {
11018 val,
11022 }
11024 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
11031 {
11033 code == NE_EXPR
11036 }
11038 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11043 /* If this is an EQ or NE comparison with zero and ARG0 is
11044 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11045 two operations, but the latter can be done in one less insn
11046 on machines that have only two-operand insns or on which a
11047 constant cannot be the first operand. */
11050 {
11055 {
11062 arg1);
11063 }
11066 {
11073 arg1);
11074 }
11075 }
11077 /* If this is an NE or EQ comparison of zero against the result of a
11078 signed MOD operation whose second operand is a power of 2, make
11079 the MOD operation unsigned since it is simpler and equivalent. */
11087 {
11097 }
11099 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11100 C1 is a valid shift constant, and C2 is a power of two, i.e.
11101 a single bit. */
11105 == INTEGER_CST
11108 {
11113 /* Check for a valid shift count. */
11115 {
11119 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11120 can be rewritten as (X & (C2 << C1)) != 0. */
11122 {
11127 }
11128 /* Otherwise, for signed (arithmetic) shifts,
11129 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11130 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11134 /* Otherwise, of unsigned (logical) shifts,
11135 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11136 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11137 else
11141 arg000);
11142 }
11143 }
11145 /* If we have (A & C) == C where C is a power of 2, convert this into
11146 (A & C) != 0. Similarly for NE_EXPR. */
11152 integer_zero_node));
11154 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11155 bit, then fold the expression into A < 0 or A >= 0. */
11160 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11161 Similarly for NE_EXPR. */
11165 {
11169 tree dandnotc
11172 notc);
11176 }
11178 /* If this is a comparison of a field, we may be able to simplify it. */
11181 /* Handle the constant case even without -O
11182 to make sure the warnings are given. */
11184 {
11188 }
11190 /* Optimize comparisons of strlen vs zero to a compare of the
11191 first character of the string vs zero. To wit,
11192 strlen(ptr) == 0 => *ptr == 0
11193 strlen(ptr) != 0 => *ptr != 0
11194 Other cases should reduce to one of these two (or a constant)
11195 due to the return value of strlen being unsigned. */
11198 {
11206 {
11211 }
11212 }
11214 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11215 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11219 {
11224 {
11226 {
11229 }
11232 }
11233 }
11235 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11236 (X & C) == 0 when C is a single bit. */
11241 {
11248 arg1));
11249 }
11251 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11252 constant C is a power of two, i.e. a single bit. */
11259 {
11263 }
11265 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11266 when is C is a power of two, i.e. a single bit. */
11273 {
11279 }
11283 {
11286 }
11288 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11291 {
11304 arg01),
11313 arg01),
11322 arg00),
11331 arg00),
11333 }
11337 {
11344 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11345 operand_equal_p guarantees no side-effects so we don't need
11346 to use omit_one_operand on Z. */
11350 arg10));
11354 arg11));
11358 arg10));
11362 arg11));
11364 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11367 {
11373 }
11374 }
11376 /* Attempt to simplify equality/inequality comparisons of complex
11377 values. Only lower the comparison if the result is known or
11378 can be simplified to a single scalar comparison. */
11383 {
11388 {
11391 }
11392 else
11393 {
11396 }
11399 {
11402 }
11403 else
11404 {
11407 }
11411 {
11413 {
11418 }
11419 else
11420 {
11425 }
11426 }
11430 {
11432 {
11437 }
11438 else
11439 {
11444 }
11445 }
11446 }
11458 /* Transform comparisons of the form X +- C CMP X. */
11465 {
11472 else
11475 /* (X - c) > X becomes false. */
11479 {
11483 "occur when assuming that (X - c) > X "
11485 WARN_STRICT_OVERFLOW_ALL);
11487 }
11489 /* Likewise (X + c) < X becomes false. */
11493 {
11497 "occur when assuming that "
11499 WARN_STRICT_OVERFLOW_ALL);
11501 }
11503 /* Convert (X - c) <= X to true. */
11508 {
11512 "occur when assuming that "
11514 WARN_STRICT_OVERFLOW_ALL);
11516 }
11518 /* Convert (X + c) >= X to true. */
11523 {
11527 "occur when assuming that "
11529 WARN_STRICT_OVERFLOW_ALL);
11531 }
11534 {
11535 /* Convert X + c > X and X - c < X to true for integers. */
11539 {
11542 "not occur when assuming that "
11544 WARN_STRICT_OVERFLOW_ALL);
11546 }
11551 {
11554 "not occur when assuming that "
11556 WARN_STRICT_OVERFLOW_ALL);
11558 }
11560 /* Convert X + c <= X and X - c >= X to false for integers. */
11564 {
11567 "not occur when assuming that "
11569 WARN_STRICT_OVERFLOW_ALL);
11571 }
11576 {
11579 "not occur when assuming that "
11581 WARN_STRICT_OVERFLOW_ALL);
11583 }
11584 }
11585 }
11587 /* If we are comparing an ABS_EXPR with a constant, we can
11588 convert all the cases into explicit comparisons, but they may
11589 well not be faster than doing the ABS and one comparison.
11590 But ABS (X) <= C is a range comparison, which becomes a subtraction
11591 and a comparison, and is probably faster. */
11605 /* Convert ABS_EXPR<x> >= 0 to true. */
11612 {
11615 "when simplifying comparison of "
11617 WARN_STRICT_OVERFLOW_CONDITIONAL);
11620 arg0);
11621 }
11623 /* Convert ABS_EXPR<x> < 0 to false. */
11628 {
11631 "when simplifying comparison of "
11633 WARN_STRICT_OVERFLOW_CONDITIONAL);
11636 arg0);
11637 }
11639 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11640 and similarly for >= into !=. */
11650 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11651 otherwise Y might be >= # of bits in X's type and thus e.g.
11652 (unsigned char) (1 << Y) for Y 15 might be 0.
11653 If the cast is widening, then 1 << Y should have unsigned type,
11654 otherwise if Y is number of bits in the signed shift type minus 1,
11655 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11656 31 might be 0xffffffff80000000. */
11667 {
11673 }
11685 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11686 {
11698 }
11703 /* When pedantic, a compound expression can be neither an lvalue
11704 nor an integer constant expression. */
11707 /* Don't let (0, 0) be null pointer constant. */
11713 /* An ASSERT_EXPR should never be passed to fold_binary. */
11719 }
11721 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11722 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11723 of GOTO_EXPR. */
11725 static tree
11727 {
11729 {
11736 /* ... fall through ... */
11740 }
11741 }
11743 /* Return whether the sub-tree ST contains a label which is accessible from
11744 outside the sub-tree. */
11746 static bool
11748 {
11749 return
11751 }
11753 /* Fold a ternary expression of code CODE and type TYPE with operands
11754 OP0, OP1, and OP2. Return the folded expression if folding is
11755 successful. Otherwise, return NULL_TREE. */
11757 tree
11760 {
11761 tree tem;
11768 /* If this is a commutative operation, and OP0 is a constant, move it
11769 to OP1 to reduce the number of tests below. */
11778 /* Strip any conversions that don't change the mode. This is safe
11779 for every expression, except for a comparison expression because
11780 its signedness is derived from its operands. So, in the latter
11781 case, only strip conversions that don't change the signedness.
11783 Note that this is done as an internal manipulation within the
11784 constant folder, in order to find the simplest representation of
11785 the arguments so that their form can be studied. In any cases,
11786 the appropriate type conversions should be put back in the tree
11787 that will get out of the constant folder. */
11789 {
11792 }
11795 {
11798 }
11801 {
11804 }
11807 {
11811 {
11817 }
11822 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11823 so all simple results must be passed through pedantic_non_lvalue. */
11825 {
11828 /* Only optimize constant conditions when the selected branch
11829 has the same type as the COND_EXPR. This avoids optimizing
11830 away "c ? x : throw", where the throw has a void type.
11831 Avoid throwing away that operand which contains label. */
11838 }
11840 {
11845 {
11850 {
11858 }
11862 }
11863 }
11865 /* If we have A op B ? A : C, we may be able to convert this to a
11866 simpler expression, depending on the operation and the values
11867 of B and C. Signed zeros prevent all of these transformations,
11868 for reasons given above each one.
11870 Also try swapping the arguments and inverting the conditional. */
11875 {
11879 }
11883 op2,
11886 {
11890 {
11894 }
11895 }
11897 /* If the second operand is simpler than the third, swap them
11898 since that produces better jump optimization results. */
11901 {
11903 /* See if this can be inverted. If it can't, possibly because
11904 it was a floating-point inequality comparison, don't do
11905 anything. */
11909 }
11911 /* Convert A ? 1 : 0 to simply A. */
11916 /* If we try to convert OP0 to our type, the
11917 call to fold will try to move the conversion inside
11918 a COND, which will recurse. In that case, the COND_EXPR
11919 is probably the best choice, so leave it alone. */
11923 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11924 over COND_EXPR in cases such as floating point comparisons. */
11933 arg0)));
11935 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11940 {
11941 /* sign_bit_p looks through both zero and sign extensions,
11942 but for this optimization only sign extensions are
11943 usable. */
11946 {
11949 {
11952 }
11954 }
11955 /* sign_bit_p only checks ARG1 bits within A's precision.
11956 If <sign bit of A> has wider type than A, bits outside
11957 of A's precision in <sign bit of A> need to be checked.
11958 If they are all 0, this optimization needs to be done
11959 in unsigned A's type, if they are all 1 in signed A's type,
11960 otherwise this can't be done. */
11966 {
11968 tree tem_type;
11981 {
11984 }
11986 {
11989 }
11990 else
11992 }
11995 return
12001 arg1)));
12002 }
12004 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12005 already handled above. */
12010 {
12019 }
12021 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12022 is probably obsolete because the first operand should be a
12023 truth value (that's why we have the two cases above), but let's
12024 leave it in until we can confirm this for all front-ends. */
12036 /* Disable the transformations below for vectors, since
12037 fold_binary_op_with_conditional_arg may undo them immediately,
12038 yielding an infinite loop. */
12042 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12051 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12056 {
12058 /* Only perform transformation if ARG0 is easily inverted. */
12062 ? BIT_IOR_EXPR
12065 arg1);
12066 }
12068 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
12073 {
12075 /* Only perform transformation if ARG0 is easily inverted. */
12081 op2);
12082 }
12084 /* Convert A ? 1 : B into A || B if A and B are truth values. */
12096 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
12097 of fold_ternary on them. */
12107 {
12117 {
12122 {
12130 }
12132 /* Constructor elements can be subvectors. */
12135 {
12139 }
12141 /* We keep an exact subset of the constructor elements. */
12143 {
12149 {
12153 }
12161 CONSTRUCTOR_ELT
12164 }
12165 /* The bitfield references a single constructor element. */
12167 {
12172 else
12176 }
12177 }
12178 }
12180 /* A bit-field-ref that referenced the full argument can be stripped. */
12186 /* On constants we can use native encode/interpret to constant
12187 fold (nearly) all BIT_FIELD_REFs. */
12191 /* This limitation should not be necessary, we just need to
12192 round this up to mode size. */
12194 /* Need bit-shifting of the buffer to relax the following. */
12196 {
12201 /* ??? We cannot tell native_encode_expr to start at
12202 some random byte only. So limit us to a reasonable amount
12203 of work. */
12205 {
12210 {
12216 }
12217 }
12218 }
12223 /* For integers we can decompose the FMA if possible. */
12235 {
12251 {
12256 /* Make sure that the perm value is in an acceptable
12257 range. */
12266 else
12271 }
12274 {
12279 }
12284 {
12289 }
12295 {
12299 }
12304 /* Some targets are deficient and fail to expand a single
12305 argument permutation while still allowing an equivalent
12306 2-argument version. */
12310 {
12313 }
12316 {
12323 }
12327 }
12333 }
12335 /* Perform constant folding and related simplification of EXPR.
12336 The related simplifications include x*1 => x, x*0 => 0, etc.,
12337 and application of the associative law.
12338 NOP_EXPR conversions may be removed freely (as long as we
12339 are careful not to change the type of the overall expression).
12340 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12341 but we can constant-fold them if they have constant operands. */
12343 #ifdef ENABLE_FOLD_CHECKING
12344 # define fold(x) fold_1 (x)
12346 static
12347 #endif
12348 tree
12350 {
12354 tree tem;
12357 /* Return right away if a constant. */
12361 /* CALL_EXPR-like objects with variable numbers of operands are
12362 treated specially. */
12364 {
12366 {
12369 }
12371 }
12374 {
12379 {
12397 }
12398 }
12401 {
12403 {
12410 {
12415 /* Find a matching index by means of a binary search. */
12417 {
12433 else
12435 }
12436 }
12439 }
12441 /* Return a VECTOR_CST if possible. */
12443 {
12450 tree value;
12453 {
12457 {
12460 }
12461 else
12463 }
12468 }
12476 }
12478 #ifdef ENABLE_FOLD_CHECKING
12479 #undef fold
12486 /* When --enable-checking=fold, compute a digest of expr before
12487 and after actual fold call to see if fold did not accidentally
12488 change original expr. */
12490 tree
12492 {
12493 tree ret;
12513 }
12515 void
12517 {
12528 }
12530 static void
12532 {
12534 }
12536 static void
12539 {
12545 recursive_label:
12555 {
12556 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12561 }
12568 {
12569 /* Allow these fields to be modified. */
12570 tree tmp;
12578 {
12581 }
12582 }
12593 {
12596 {
12611 }
12615 {
12628 }
12645 {
12651 }
12654 {
12656 {
12659 }
12661 }
12672 {
12675 }
12685 }
12686 }
12688 /* Helper function for outputting the checksum of a tree T. When
12689 debugging with gdb, you can "define mynext" to be "next" followed
12690 by "call debug_fold_checksum (op0)", then just trace down till the
12691 outputs differ. */
12693 DEBUG_FUNCTION void
12695 {
12710 }
12712 #endif
12714 /* Fold a unary tree expression with code CODE of type TYPE with an
12715 operand OP0. LOC is the location of the resulting expression.
12716 Return a folded expression if successful. Otherwise, return a tree
12717 expression with code CODE of type TYPE with an operand OP0. */
12719 tree
12722 {
12723 tree tem;
12724 #ifdef ENABLE_FOLD_CHECKING
12733 #endif
12739 #ifdef ENABLE_FOLD_CHECKING
12746 #endif
12748 }
12750 /* Fold a binary tree expression with code CODE of type TYPE with
12751 operands OP0 and OP1. LOC is the location of the resulting
12752 expression. Return a folded expression if successful. Otherwise,
12753 return a tree expression with code CODE of type TYPE with operands
12754 OP0 and OP1. */
12756 tree
12759 MEM_STAT_DECL)
12760 {
12761 tree tem;
12762 #ifdef ENABLE_FOLD_CHECKING
12779 #endif
12785 #ifdef ENABLE_FOLD_CHECKING
12800 #endif
12802 }
12804 /* Fold a ternary tree expression with code CODE of type TYPE with
12805 operands OP0, OP1, and OP2. Return a folded expression if
12806 successful. Otherwise, return a tree expression with code CODE of
12807 type TYPE with operands OP0, OP1, and OP2. */
12809 tree
12812 {
12813 tree tem;
12814 #ifdef ENABLE_FOLD_CHECKING
12838 #endif
12845 #ifdef ENABLE_FOLD_CHECKING
12868 #endif
12870 }
12872 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12873 arguments in ARGARRAY, and a null static chain.
12874 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12875 of type TYPE from the given operands as constructed by build_call_array. */
12877 tree
12880 {
12881 tree tem;
12882 #ifdef ENABLE_FOLD_CHECKING
12901 #endif
12907 #ifdef ENABLE_FOLD_CHECKING
12923 #endif
12925 }
12927 /* Perform constant folding and related simplification of initializer
12928 expression EXPR. These behave identically to "fold_buildN" but ignore
12929 potential run-time traps and exceptions that fold must preserve. */
12931 #define START_FOLD_INIT \
12932 int saved_signaling_nans = flag_signaling_nans;\
12933 int saved_trapping_math = flag_trapping_math;\
12934 int saved_rounding_math = flag_rounding_math;\
12935 int saved_trapv = flag_trapv;\
12936 int saved_folding_initializer = folding_initializer;\
12937 flag_signaling_nans = 0;\
12938 flag_trapping_math = 0;\
12939 flag_rounding_math = 0;\
12940 flag_trapv = 0;\
12941 folding_initializer = 1;
12943 #define END_FOLD_INIT \
12944 flag_signaling_nans = saved_signaling_nans;\
12945 flag_trapping_math = saved_trapping_math;\
12946 flag_rounding_math = saved_rounding_math;\
12947 flag_trapv = saved_trapv;\
12948 folding_initializer = saved_folding_initializer;
12950 tree
12953 {
12954 tree result;
12955 START_FOLD_INIT;
12959 END_FOLD_INIT;
12961 }
12963 tree
12966 {
12967 tree result;
12968 START_FOLD_INIT;
12972 END_FOLD_INIT;
12974 }
12976 tree
12979 {
12980 tree result;
12981 START_FOLD_INIT;
12985 END_FOLD_INIT;
12987 }
12989 #undef START_FOLD_INIT
12990 #undef END_FOLD_INIT
12992 /* Determine if first argument is a multiple of second argument. Return 0 if
12993 it is not, or we cannot easily determined it to be.
12995 An example of the sort of thing we care about (at this point; this routine
12996 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12997 fold cases do now) is discovering that
12999 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13001 is a multiple of
13003 SAVE_EXPR (J * 8)
13005 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13007 This code also handles discovering that
13009 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13011 is a multiple of 8 so we don't have to worry about dealing with a
13012 possible remainder.
13014 Note that we *look* inside a SAVE_EXPR only to determine how it was
13015 calculated; it is not safe for fold to do much of anything else with the
13016 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13017 at run time. For example, the latter example above *cannot* be implemented
13018 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13019 evaluation time of the original SAVE_EXPR is not necessarily the same at
13020 the time the new expression is evaluated. The only optimization of this
13021 sort that would be valid is changing
13023 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13025 divided by 8 to
13027 SAVE_EXPR (I) * SAVE_EXPR (J)
13029 (where the same SAVE_EXPR (J) is used in the original and the
13030 transformed version). */
13032 int
13034 {
13042 {
13044 /* Bitwise and provides a power of two multiple. If the mask is
13045 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13048 /* FALLTHRU */
13061 {
13065 /* const_binop may not detect overflow correctly,
13066 so check for it explicitly here. */
13070 size_one_node,
13071 op1)))
13074 }
13078 /* Can't handle conversions from non-integral or wider integral type. */
13084 /* .. fall through ... */
13101 SIGNED);
13105 }
13106 }
13108 /* Return true if CODE or TYPE is known to be non-negative. */
13110 static bool
13112 {
13115 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
13116 have a signed:1 type (where the value is -1 and 0). */
13119 }
13121 /* Return true if (CODE OP0) is known to be non-negative. If the return
13122 value is based on the assumption that signed overflow is undefined,
13123 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13124 *STRICT_OVERFLOW_P. */
13126 bool
13129 {
13134 {
13136 /* We can't return 1 if flag_wrapv is set because
13137 ABS_EXPR<INT_MIN> = INT_MIN. */
13141 {
13144 }
13151 strict_overflow_p);
13153 CASE_CONVERT:
13154 {
13159 {
13162 strict_overflow_p);
13164 {
13168 strict_overflow_p);
13169 }
13170 }
13172 {
13175 strict_overflow_p);
13179 }
13180 }
13185 }
13187 /* We don't know sign of `t', so be conservative and return false. */
13189 }
13191 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
13192 value is based on the assumption that signed overflow is undefined,
13193 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13194 *STRICT_OVERFLOW_P. */
13196 bool
13199 {
13204 {
13209 strict_overflow_p)
13211 strict_overflow_p));
13213 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13214 both unsigned and at least 2 bits shorter than the result. */
13218 {
13223 {
13227 }
13228 }
13233 {
13234 /* x * x is always non-negative for floating point x
13235 or without overflow. */
13239 {
13244 }
13245 }
13247 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13248 both unsigned and their total bits is shorter than the result. */
13252 {
13271 {
13281 }
13282 }
13288 strict_overflow_p)
13290 strict_overflow_p));
13301 strict_overflow_p)
13303 strict_overflow_p));
13310 strict_overflow_p);
13313 }
13315 /* We don't know sign of `t', so be conservative and return false. */
13317 }
13319 /* Return true if T is known to be non-negative. If the return
13320 value is based on the assumption that signed overflow is undefined,
13321 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13322 *STRICT_OVERFLOW_P. */
13324 bool
13326 {
13331 {
13343 strict_overflow_p)
13345 strict_overflow_p));
13349 }
13350 /* We don't know sign of `t', so be conservative and return false. */
13352 }
13354 /* Return true if T is known to be non-negative. If the return
13355 value is based on the assumption that signed overflow is undefined,
13356 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13357 *STRICT_OVERFLOW_P. */
13359 bool
13362 {
13365 {
13385 /* Always true. */
13389 /* sqrt(-0.0) is -0.0. */
13393 strict_overflow_p);
13430 /* True if the 1st argument is nonnegative. */
13432 strict_overflow_p);
13435 /* True if the 1st OR 2nd arguments are nonnegative. */
13437 strict_overflow_p)
13439 strict_overflow_p)));
13442 /* True if the 1st AND 2nd arguments are nonnegative. */
13444 strict_overflow_p)
13446 strict_overflow_p)));
13449 /* True if the 2nd argument is nonnegative. */
13451 strict_overflow_p);
13454 /* True if the 1st argument is nonnegative or the second
13455 argument is an even integer. */
13460 strict_overflow_p);
13463 /* True if the 1st argument is nonnegative or the second
13464 argument is an even integer valued real. */
13466 {
13467 REAL_VALUE_TYPE c;
13468 HOST_WIDE_INT n;
13473 {
13474 REAL_VALUE_TYPE cint;
13478 }
13479 }
13481 strict_overflow_p);
13485 }
13487 type);
13488 }
13490 /* Return true if T is known to be non-negative. If the return
13491 value is based on the assumption that signed overflow is undefined,
13492 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13493 *STRICT_OVERFLOW_P. */
13495 static bool
13497 {
13503 {
13505 {
13509 /* If the initializer is non-void, then it's a normal expression
13510 that will be assigned to the slot. */
13514 /* Otherwise, the initializer sets the slot in some way. One common
13515 way is an assignment statement at the end of the initializer. */
13517 {
13525 else
13527 }
13531 strict_overflow_p);
13534 }
13537 {
13543 arg0,
13544 arg1,
13545 strict_overflow_p);
13546 }
13550 strict_overflow_p);
13553 strict_overflow_p);
13556 strict_overflow_p);
13561 }
13563 /* We don't know sign of `t', so be conservative and return false. */
13565 }
13567 /* Return true if T is known to be non-negative. If the return
13568 value is based on the assumption that signed overflow is undefined,
13569 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13570 *STRICT_OVERFLOW_P. */
13572 bool
13574 {
13581 {
13588 strict_overflow_p);
13594 strict_overflow_p);
13603 }
13606 {
13614 strict_overflow_p);
13619 strict_overflow_p);
13632 }
13633 }
13635 /* Return true if `t' is known to be non-negative. Handle warnings
13636 about undefined signed overflow. */
13638 bool
13640 {
13647 "determining that expression is always "
13649 WARN_STRICT_OVERFLOW_MISC);
13651 }
13654 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13655 For floating point we further ensure that T is not denormal.
13656 Similar logic is present in nonzero_address in rtlanal.h.
13658 If the return value is based on the assumption that signed overflow
13659 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13660 change *STRICT_OVERFLOW_P. */
13662 bool
13665 {
13667 {
13670 strict_overflow_p);
13673 {
13679 strict_overflow_p));
13680 }
13685 strict_overflow_p);
13689 }
13692 }
13694 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13695 For floating point we further ensure that T is not denormal.
13696 Similar logic is present in nonzero_address in rtlanal.h.
13698 If the return value is based on the assumption that signed overflow
13699 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13700 change *STRICT_OVERFLOW_P. */
13702 bool
13704 tree type,
13705 tree op0,
13707 {
13710 {
13714 {
13715 /* With the presence of negative values it is hard
13716 to say something. */
13723 /* One of operands must be positive and the other non-negative. */
13724 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13725 overflows, on a twos-complement machine the sum of two
13726 nonnegative numbers can never be zero. */
13728 strict_overflow_p)
13730 strict_overflow_p));
13731 }
13736 {
13738 strict_overflow_p)
13740 strict_overflow_p))
13741 {
13744 }
13745 }
13754 {
13757 }
13764 {
13768 /* When both operands are nonzero, then MAX must be too. */
13770 strict_overflow_p))
13773 /* MAX where operand 0 is positive is positive. */
13775 strict_overflow_p);
13776 }
13777 /* MAX where operand 1 is positive is positive. */
13782 {
13786 }
13791 strict_overflow_p)
13793 strict_overflow_p));
13797 }
13800 }
13802 /* Return true when T is an address and is known to be nonzero.
13803 For floating point we further ensure that T is not denormal.
13804 Similar logic is present in nonzero_address in rtlanal.h.
13806 If the return value is based on the assumption that signed overflow
13807 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13808 change *STRICT_OVERFLOW_P. */
13810 bool
13812 {
13815 {
13820 {
13829 /* For objects in symbol table check if we know they are non-zero.
13830 Don't do anything for variables and functions before symtab is built;
13831 it is quite possible that they will be declared weak later. */
13833 {
13839 else
13841 }
13843 /* Function local objects are never NULL. */
13850 /* Constants are never weak. */
13855 }
13863 {
13867 }
13872 }
13874 }
13876 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13877 attempt to fold the expression to a constant without modifying TYPE,
13878 OP0 or OP1.
13880 If the expression could be simplified to a constant, then return
13881 the constant. If the expression would not be simplified to a
13882 constant, then return NULL_TREE. */
13884 tree
13886 {
13889 }
13891 /* Given the components of a unary expression CODE, TYPE and OP0,
13892 attempt to fold the expression to a constant without modifying
13893 TYPE or OP0.
13895 If the expression could be simplified to a constant, then return
13896 the constant. If the expression would not be simplified to a
13897 constant, then return NULL_TREE. */
13899 tree
13901 {
13904 }
13906 /* If EXP represents referencing an element in a constant string
13907 (either via pointer arithmetic or array indexing), return the
13908 tree representing the value accessed, otherwise return NULL. */
13910 tree
13912 {
13916 {
13918 tree index;
13919 tree string;
13924 else
13925 {
13929 /* Optimize the special-case of a zero lower bound.
13931 We convert the low_bound to sizetype to avoid some problems
13932 with constant folding. (E.g. suppose the lower bound is 1,
13933 and its mode is QI. Without the conversion,l (ARRAY
13934 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13935 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13941 }
13954 }
13956 }
13958 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13959 an integer constant, real, or fixed-point constant.
13961 TYPE is the type of the result. */
13963 static tree
13965 {
13969 {
13971 {
13978 }
13985 {
13986 FIXED_VALUE_TYPE f;
13991 /* Propagate overflow flags. */
13995 }
13999 }
14002 }
14004 /* Return the tree for abs (ARG0) when ARG0 is known to be either
14005 an integer constant or real constant.
14007 TYPE is the type of the result. */
14009 tree
14011 {
14015 {
14017 {
14018 /* If the value is unsigned or non-negative, then the absolute value
14019 is the same as the ordinary value. */
14023 /* If the value is negative, then the absolute value is
14024 its negation. */
14025 else
14026 {
14031 }
14032 }
14038 else
14044 }
14047 }
14049 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
14050 constant. TYPE is the type of the result. */
14052 static tree
14054 {
14058 }
14060 /* Given CODE, a relational operator, the target type, TYPE and two
14061 constant operands OP0 and OP1, return the result of the
14062 relational operation. If the result is not a compile time
14063 constant, then return NULL_TREE. */
14065 static tree
14067 {
14070 /* From here on, the only cases we handle are when the result is
14071 known to be a constant. */
14074 {
14078 /* Handle the cases where either operand is a NaN. */
14080 {
14082 {
14110 }
14113 }
14116 }
14119 {
14123 }
14125 /* Handle equality/inequality of complex constants. */
14127 {
14138 else
14140 }
14143 {
14150 {
14162 }
14165 }
14167 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14169 To compute GT, swap the arguments and do LT.
14170 To compute GE, do LT and invert the result.
14171 To compute LE, swap the arguments, do LT and invert the result.
14172 To compute NE, do EQ and invert the result.
14174 Therefore, the code below must handle only EQ and LT. */
14177 {
14180 }
14182 /* Note that it is safe to invert for real values here because we
14183 have already handled the one case that it matters. */
14187 {
14190 }
14192 /* Compute a result for LT or EQ if args permit;
14193 Otherwise return T. */
14195 {
14198 else
14200 }
14201 else
14207 }
14209 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14210 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14211 itself. */
14213 tree
14215 {
14216 /* If the expression does not have side effects then we don't have to wrap
14217 it with a cleanup point expression. */
14221 /* If the expression is a return, check to see if the expression inside the
14222 return has no side effects or the right hand side of the modify expression
14223 inside the return. If either don't have side effects set we don't need to
14224 wrap the expression in a cleanup point expression. Note we don't check the
14225 left hand side of the modify because it should always be a return decl. */
14227 {
14234 }
14237 }
14239 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14240 of an indirection through OP0, or NULL_TREE if no simplification is
14241 possible. */
14243 tree
14245 {
14247 tree subtype;
14255 {
14258 /* *&CONST_DECL -> to the value of the const decl. */
14261 /* *&p => p; make sure to handle *&"str"[cst] here. */
14263 {
14267 else
14269 }
14270 /* *(foo *)&fooarray => fooarray[0] */
14273 && (!in_gimple_form
14275 {
14285 }
14286 /* *(foo *)&complexfoo => __real__ complexfoo */
14290 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14293 {
14297 }
14298 }
14302 {
14308 {
14309 tree op00type;
14313 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14316 {
14328 }
14329 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14332 {
14336 }
14337 /* ((foo *)&fooarray)[1] => fooarray[1] */
14340 {
14350 }
14351 }
14352 }
14354 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14357 && (!in_gimple_form
14359 {
14360 tree type_domain;
14370 NULL_TREE);
14371 }
14374 }
14376 /* Builds an expression for an indirection through T, simplifying some
14377 cases. */
14379 tree
14381 {
14389 }
14391 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14393 tree
14395 {
14400 else
14402 }
14404 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14405 whose result is ignored. The type of the returned tree need not be
14406 the same as the original expression. */
14408 tree
14410 {
14416 {
14427 else
14433 {
14449 }
14454 }
14455 }
14457 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14459 tree
14461 {
14467 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14468 have to do anything. Only do this when we are not given a const,
14469 because in that case, this check is more expensive than just
14470 doing it. */
14472 {
14477 }
14479 /* If divisor is a power of two, simplify this to bit manipulation. */
14481 {
14483 {
14497 }
14498 else
14499 {
14500 tree t;
14506 }
14507 }
14508 else
14509 {
14514 }
14517 }
14519 /* Likewise, but round down. */
14521 tree
14523 {
14530 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14531 have to do anything. Only do this when we are not given a const,
14532 because in that case, this check is more expensive than just
14533 doing it. */
14535 {
14540 }
14542 /* If divisor is a power of two, simplify this to bit manipulation. */
14544 {
14545 tree t;
14549 }
14550 else
14551 {
14556 }
14559 }
14561 /* Returns the pointer to the base of the object addressed by EXP and
14562 extracts the information about the offset of the access, storing it
14563 to PBITPOS and POFFSET. */
14565 static tree
14568 {
14569 tree core;
14570 machine_mode mode;
14572 HOST_WIDE_INT bitsize;
14576 {
14581 }
14582 else
14583 {
14587 }
14590 }
14592 /* Returns true if addresses of E1 and E2 differ by a constant, false
14593 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14595 bool
14597 {
14611 {
14621 }
14623 {
14624 /* If only one of the offsets is non-constant, the difference cannot
14625 be a constant. */
14627 }
14628 else
14633 }
14635 /* Simplify the floating point expression EXP when the sign of the
14636 result is not significant. Return NULL_TREE if no simplification
14637 is possible. */
14639 tree
14641 {
14646 {
14682 {
14685 {
14687 /* Strip copysign function call, return the 1st argument. */
14693 /* Strip sign ops from the argument of "odd" math functions. */
14695 {
14699 }
14701 }
14702 }
14707 }
14709 }
14711 /* Return OFF converted to a pointer offset type suitable as offset for
14712 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14713 tree
14715 {
14717 }
14719 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14720 tree
14722 {
14725 }
14727 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14728 tree
14730 {
14733 }