| blob | c140c62856bb65be5cb9a589b81b2787f1e791aa |
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 {
2757 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2759 ;
2761 {
2762 /* If we are interested in comparing addresses ignore
2763 MEM_REF wrappings of the base that can appear just for
2764 TBAA reasons. */
2778 }
2779 else
2781 }
2783 /* This is needed for conversions and for COMPONENT_REF.
2784 Might as well play it safe and always test this. */
2790 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2791 We don't care about side effects in that case because the SAVE_EXPR
2792 takes care of that for us. In all other cases, two expressions are
2793 equal if they have no side effects. If we have two identical
2794 expressions with side effects that should be treated the same due
2795 to the only side effects being identical SAVE_EXPR's, that will
2796 be detected in the recursive calls below.
2797 If we are taking an invariant address of two identical objects
2798 they are necessarily equal as well. */
2805 /* Next handle constant cases, those for which we can return 1 even
2806 if ONLY_CONST is set. */
2809 {
2824 {
2825 /* If we do not distinguish between signed and unsigned zero,
2826 consider them equal. */
2829 }
2833 {
2840 {
2844 }
2846 }
2850 flags)
2852 flags));
2866 }
2871 /* Define macros to test an operand from arg0 and arg1 for equality and a
2872 variant that allows null and views null as being different from any
2873 non-null value. In the latter case, if either is null, the both
2874 must be; otherwise, do the normal comparison. */
2875 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2876 TREE_OPERAND (arg1, N), flags)
2878 #define OP_SAME_WITH_NULL(N) \
2879 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2880 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2883 {
2885 /* Two conversions are equal only if signedness and modes match. */
2887 {
2888 CASE_CONVERT:
2896 }
2906 /* For commutative ops, allow the other order. */
2914 /* If either of the pointer (or reference) expressions we are
2915 dereferencing contain a side effect, these cannot be equal,
2916 but their addresses can be. */
2923 {
2938 /* Require equal access sizes, and similar pointer types.
2939 We can have incomplete types for array references of
2940 variable-sized arrays from the Fortran frontend
2941 though. Also verify the types are compatible. */
2949 || (alias_ptr_types_compatible_p
2961 /* TARGET_MEM_REF require equal extra operands. */
2969 /* Operands 2 and 3 may be null.
2970 Compare the array index by value if it is constant first as we
2971 may have different types but same value here. */
2982 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2983 may be NULL when we're called to compare MEM_EXPRs. */
2998 }
3002 {
3020 /* The multiplcation operands are commutative. */
3021 /* FALLTHRU */
3029 /* Otherwise take into account this is a commutative operation. */
3042 }
3046 {
3050 /* If not both CALL_EXPRs are either internal or normal function
3051 functions, then they are not equal. */
3054 {
3055 /* If the CALL_EXPRs call different internal functions, then they
3056 are not equal. */
3059 }
3060 else
3061 {
3062 /* If the CALL_EXPRs call different functions, then they are not
3063 equal. */
3065 flags))
3067 }
3069 {
3073 else
3077 }
3079 /* Now see if all the arguments are the same. */
3080 {
3091 /* If we get here and both argument lists are exhausted
3092 then the CALL_EXPRs are equal. */
3094 }
3097 }
3100 /* Consider __builtin_sqrt equal to sqrt. */
3108 }
3110 #undef OP_SAME
3111 #undef OP_SAME_WITH_NULL
3112 }
3113 \f
3114 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3115 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3117 When in doubt, return 0. */
3119 static int
3121 {
3133 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3134 and see if the inner values are the same. This removes any
3135 signedness comparison, which doesn't matter here. */
3142 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3143 actual comparison operand, ARG0.
3145 First throw away any conversions to wider types
3146 already present in the operands. */
3155 {
3158 /* Make sure shorter operand is extended the right way
3159 to match the longer operand. */
3165 }
3168 }
3169 \f
3170 /* See if ARG is an expression that is either a comparison or is performing
3171 arithmetic on comparisons. The comparisons must only be comparing
3172 two different values, which will be stored in *CVAL1 and *CVAL2; if
3173 they are nonzero it means that some operands have already been found.
3174 No variables may be used anywhere else in the expression except in the
3175 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3176 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3178 If this is true, return 1. Otherwise, return zero. */
3180 static int
3182 {
3186 /* We can handle some of the tcc_expression cases here. */
3196 {
3197 /* If we've already found a CVAL1 or CVAL2, this expression is
3198 two complex to handle. */
3204 }
3207 {
3230 /* First see if we can handle the first operand, then the second. For
3231 the second operand, we know *CVAL1 can't be zero. It must be that
3232 one side of the comparison is each of the values; test for the
3233 case where this isn't true by failing if the two operands
3234 are the same. */
3243 ;
3247 ;
3248 else
3252 ;
3256 ;
3257 else
3264 }
3265 }
3266 \f
3267 /* ARG is a tree that is known to contain just arithmetic operations and
3268 comparisons. Evaluate the operations in the tree substituting NEW0 for
3269 any occurrence of OLD0 as an operand of a comparison and likewise for
3270 NEW1 and OLD1. */
3272 static tree
3275 {
3280 /* We can handle some of the tcc_expression cases here. */
3288 {
3303 {
3322 }
3323 /* Fall through - ??? */
3326 {
3330 /* We need to check both for exact equality and tree equality. The
3331 former will be true if the operand has a side-effect. In that
3332 case, we know the operand occurred exactly once. */
3345 }
3349 }
3350 }
3351 \f
3352 /* Return a tree for the case when the result of an expression is RESULT
3353 converted to TYPE and OMITTED was previously an operand of the expression
3354 but is now not needed (e.g., we folded OMITTED * 0).
3356 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3357 the conversion of RESULT to TYPE. */
3359 tree
3361 {
3364 /* If the resulting operand is an empty statement, just return the omitted
3365 statement casted to void. */
3375 }
3377 /* Return a tree for the case when the result of an expression is RESULT
3378 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3379 of the expression but are now not needed.
3381 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3382 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3383 evaluated before OMITTED2. Otherwise, if neither has side effects,
3384 just do the conversion of RESULT to TYPE. */
3386 tree
3389 {
3398 }
3400 \f
3401 /* Return a simplified tree node for the truth-negation of ARG. This
3402 never alters ARG itself. We assume that ARG is an operation that
3403 returns a truth value (0 or 1).
3405 FIXME: one would think we would fold the result, but it causes
3406 problems with the dominator optimizer. */
3408 static tree
3410 {
3415 /* If this is a comparison, we can simply invert it, except for
3416 floating-point non-equality comparisons, in which case we just
3417 enclose a TRUTH_NOT_EXPR around what we have. */
3420 {
3423 && flag_trapping_math
3434 }
3437 {
3456 /* Here we can invert either operand. We invert the first operand
3457 unless the second operand is a TRUTH_NOT_EXPR in which case our
3458 result is the XOR of the first operand with the inside of the
3459 negation of the second operand. */
3464 else
3487 {
3494 /* A COND_EXPR may have a throw as one operand, which
3495 then has void type. Just leave void operands
3496 as they are. */
3502 }
3514 CASE_CONVERT:
3518 /* ... fall through ... */
3540 }
3541 }
3543 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3544 assume that ARG is an operation that returns a truth value (0 or 1
3545 for scalars, 0 or -1 for vectors). Return the folded expression if
3546 folding is successful. Otherwise, return NULL_TREE. */
3548 static tree
3550 {
3553 ? BIT_NOT_EXPR
3556 }
3558 /* Return a simplified tree node for the truth-negation of ARG. This
3559 never alters ARG itself. We assume that ARG is an operation that
3560 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3562 tree
3564 {
3570 ? BIT_NOT_EXPR
3573 }
3575 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3576 with code CODE. This optimization is unsafe. */
3577 static tree
3580 {
3584 /* (A / C) +- (B / C) -> (A +- B) / C. */
3594 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3599 {
3611 }
3614 }
3615 \f
3616 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3617 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3619 static tree
3622 {
3626 {
3633 }
3647 }
3649 /* Optimize a bit-field compare.
3651 There are two cases: First is a compare against a constant and the
3652 second is a comparison of two items where the fields are at the same
3653 bit position relative to the start of a chunk (byte, halfword, word)
3654 large enough to contain it. In these cases we can avoid the shift
3655 implicit in bitfield extractions.
3657 For constants, we emit a compare of the shifted constant with the
3658 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3659 compared. For two fields at the same position, we do the ANDs with the
3660 similar mask and compare the result of the ANDs.
3662 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3663 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3664 are the left and right operands of the comparison, respectively.
3666 If the optimization described above can be done, we return the resulting
3667 tree. Otherwise we return zero. */
3669 static tree
3672 {
3675 tree unsigned_type;
3681 tree mask;
3682 tree offset;
3684 /* Get all the information about the extractions being done. If the bit size
3685 if the same as the size of the underlying object, we aren't doing an
3686 extraction at all and so can do nothing. We also don't want to
3687 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3688 then will no longer be able to replace it. */
3696 {
3697 /* If this is not a constant, we can only do something if bit positions,
3698 sizes, and signedness are the same. */
3706 }
3708 /* See if we can find a mode to refer to this field. We should be able to,
3709 but fail if we can't. */
3718 /* Set signed and unsigned types of the precision of this mode for the
3719 shifts below. */
3722 /* Compute the bit position and size for the new reference and our offset
3723 within it. If the new reference is the same size as the original, we
3724 won't optimize anything, so return zero. */
3734 /* Make the mask to be used against the extracted field. */
3741 /* If not comparing with constant, just rework the comparison
3742 and return. */
3746 unsigned_type,
3749 mask),
3752 unsigned_type,
3755 mask));
3757 /* Otherwise, we are handling the constant case. See if the constant is too
3758 big for the field. Warn and return a tree of for 0 (false) if so. We do
3759 this not only for its own sake, but to avoid having to test for this
3760 error case below. If we didn't, we might generate wrong code.
3762 For unsigned fields, the constant shifted right by the field length should
3763 be all zero. For signed fields, the high-order bits should agree with
3764 the sign bit. */
3767 {
3769 {
3773 }
3774 }
3775 else
3776 {
3779 {
3783 }
3784 }
3786 /* Single-bit compares should always be against zero. */
3788 {
3791 }
3793 /* Make a new bitfield reference, shift the constant over the
3794 appropriate number of bits and mask it with the computed mask
3795 (in case this was a signed field). If we changed it, make a new one. */
3802 mask);
3807 }
3808 \f
3809 /* Subroutine for fold_truth_andor_1: decode a field reference.
3811 If EXP is a comparison reference, we return the innermost reference.
3813 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3814 set to the starting bit number.
3816 If the innermost field can be completely contained in a mode-sized
3817 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3819 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3820 otherwise it is not changed.
3822 *PUNSIGNEDP is set to the signedness of the field.
3824 *PMASK is set to the mask used. This is either contained in a
3825 BIT_AND_EXPR or derived from the width of the field.
3827 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3829 Return 0 if this is not a component reference or is one that we can't
3830 do anything with. */
3832 static tree
3837 {
3841 tree unsigned_type;
3844 /* All the optimizations using this function assume integer fields.
3845 There are problems with FP fields since the type_for_size call
3846 below can fail for, e.g., XFmode. */
3850 /* We are interested in the bare arrangement of bits, so strip everything
3851 that doesn't affect the machine mode. However, record the type of the
3852 outermost expression if it may matter below. */
3859 {
3865 }
3874 /* If the number of bits in the reference is the same as the bitsize of
3875 the outer type, then the outer type gives the signedness. Otherwise
3876 (in case of a small bitfield) the signedness is unchanged. */
3880 /* Compute the mask to access the bitfield. */
3889 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3897 }
3899 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3900 bit positions and MASK is SIGNED. */
3902 static int
3904 {
3908 /* If this function returns true when the type of the mask is
3909 UNSIGNED, then there will be errors. In particular see
3910 gcc.c-torture/execute/990326-1.c. There does not appear to be
3911 any documentation paper trail as to why this is so. But the pre
3912 wide-int worked with that restriction and it has been preserved
3913 here. */
3918 }
3920 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3921 represents the sign bit of EXP's type. If EXP represents a sign
3922 or zero extension, also test VAL against the unextended type.
3923 The return value is the (sub)expression whose sign bit is VAL,
3924 or NULL_TREE otherwise. */
3926 tree
3928 {
3930 tree t;
3932 /* Tree EXP must have an integral type. */
3937 /* Tree VAL must be an integer constant. */
3946 /* Handle extension from a narrower type. */
3952 }
3954 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3955 to be evaluated unconditionally. */
3957 static int
3959 {
3960 /* Strip any conversions that don't change the machine mode. */
3969 /* Don't regard global variables as simple. They may be
3970 allocated in ways unknown to the compiler (shared memory,
3971 #pragma weak, etc). */
3974 /* Weakrefs are not safe to be read, since they can be NULL.
3975 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
3976 have DECL_WEAK flag set. */
3978 /* Loading a static variable is unduly expensive, but global
3979 registers aren't expensive. */
3981 }
3983 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
3984 to be evaluated unconditionally.
3985 I addition to simple_operand_p, we assume that comparisons, conversions,
3986 and logic-not operations are simple, if their operands are simple, too. */
3988 static bool
3990 {
4010 }
4012 \f
4013 /* The following functions are subroutines to fold_range_test and allow it to
4014 try to change a logical combination of comparisons into a range test.
4016 For example, both
4017 X == 2 || X == 3 || X == 4 || X == 5
4018 and
4019 X >= 2 && X <= 5
4020 are converted to
4021 (unsigned) (X - 2) <= 3
4023 We describe each set of comparisons as being either inside or outside
4024 a range, using a variable named like IN_P, and then describe the
4025 range with a lower and upper bound. If one of the bounds is omitted,
4026 it represents either the highest or lowest value of the type.
4028 In the comments below, we represent a range by two numbers in brackets
4029 preceded by a "+" to designate being inside that range, or a "-" to
4030 designate being outside that range, so the condition can be inverted by
4031 flipping the prefix. An omitted bound is represented by a "-". For
4032 example, "- [-, 10]" means being outside the range starting at the lowest
4033 possible value and ending at 10, in other words, being greater than 10.
4034 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4035 always false.
4037 We set up things so that the missing bounds are handled in a consistent
4038 manner so neither a missing bound nor "true" and "false" need to be
4039 handled using a special case. */
4041 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4042 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4043 and UPPER1_P are nonzero if the respective argument is an upper bound
4044 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4045 must be specified for a comparison. ARG1 will be converted to ARG0's
4046 type if both are specified. */
4048 static tree
4051 {
4052 tree tem;
4056 /* If neither arg represents infinity, do the normal operation.
4057 Else, if not a comparison, return infinity. Else handle the special
4058 comparison rules. Note that most of the cases below won't occur, but
4059 are handled for consistency. */
4062 {
4067 }
4072 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4073 for neither. In real maths, we cannot assume open ended ranges are
4074 the same. But, this is computer arithmetic, where numbers are finite.
4075 We can therefore make the transformation of any unbounded range with
4076 the value Z, Z being greater than any representable number. This permits
4077 us to treat unbounded ranges as equal. */
4081 {
4102 }
4105 }
4106 \f
4107 /* Helper routine for make_range. Perform one step for it, return
4108 new expression if the loop should continue or NULL_TREE if it should
4109 stop. */
4111 tree
4115 {
4121 {
4123 /* We can only do something if the range is testing for zero. */
4132 /* We can only do something if the range is testing for zero
4133 and if the second operand is an integer constant. Note that
4134 saying something is "in" the range we make is done by
4135 complementing IN_P since it will set in the initial case of
4136 being not equal to zero; "out" is leaving it alone. */
4143 {
4164 }
4166 /* If this is an unsigned comparison, we also know that EXP is
4167 greater than or equal to zero. We base the range tests we make
4168 on that fact, so we record it here so we can parse existing
4169 range tests. We test arg0_type since often the return type
4170 of, e.g. EQ_EXPR, is boolean. */
4172 {
4176 NULL_TREE))
4181 /* If the high bound is missing, but we have a nonzero low
4182 bound, reverse the range so it goes from zero to the low bound
4183 minus 1. */
4185 {
4190 }
4191 }
4199 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4200 low and high are non-NULL, then normalize will DTRT. */
4203 {
4208 }
4210 /* (-x) IN [a,b] -> x in [-b, -a] */
4222 /* ~ X -> -X - 1 */
4231 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4232 move a constant to the other side. */
4237 /* If EXP is signed, any overflow in the computation is undefined,
4238 so we don't worry about it so long as our computations on
4239 the bounds don't overflow. For unsigned, overflow is defined
4240 and this is exactly the right thing. */
4252 normalize:
4253 /* Check for an unsigned range which has wrapped around the maximum
4254 value thus making n_high < n_low, and normalize it. */
4256 {
4262 /* If the range is of the form +/- [ x+1, x ], we won't
4263 be able to normalize it. But then, it represents the
4264 whole range or the empty set, so make it
4265 +/- [ -, - ]. */
4269 else
4271 }
4272 else
4280 CASE_CONVERT:
4298 /* If we're converting arg0 from an unsigned type, to exp,
4299 a signed type, we will be doing the comparison as unsigned.
4300 The tests above have already verified that LOW and HIGH
4301 are both positive.
4303 So we have to ensure that we will handle large unsigned
4304 values the same way that the current signed bounds treat
4305 negative values. */
4308 {
4309 tree high_positive;
4310 tree equiv_type;
4311 /* For fixed-point modes, we need to pass the saturating flag
4312 as the 2nd parameter. */
4314 equiv_type
4317 else
4318 equiv_type
4321 /* A range without an upper bound is, naturally, unbounded.
4322 Since convert would have cropped a very large value, use
4323 the max value for the destination type. */
4324 high_positive
4331 high_positive),
4334 /* If the low bound is specified, "and" the range with the
4335 range for which the original unsigned value will be
4336 positive. */
4338 {
4341 integer_zero_node),
4342 high_positive))
4346 }
4347 else
4348 {
4349 /* Otherwise, "or" the range with the range of the input
4350 that will be interpreted as negative. */
4353 integer_zero_node),
4354 high_positive))
4358 }
4359 }
4368 }
4369 }
4371 /* Given EXP, a logical expression, set the range it is testing into
4372 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4373 actually being tested. *PLOW and *PHIGH will be made of the same
4374 type as the returned expression. If EXP is not a comparison, we
4375 will most likely not be returning a useful value and range. Set
4376 *STRICT_OVERFLOW_P to true if the return value is only valid
4377 because signed overflow is undefined; otherwise, do not change
4378 *STRICT_OVERFLOW_P. */
4380 tree
4383 {
4391 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4392 and see if we can refine the range. Some of the cases below may not
4393 happen, but it doesn't seem worth worrying about this. We "continue"
4394 the outer loop when we've changed something; otherwise we "break"
4395 the switch, which will "break" the while. */
4401 {
4407 {
4415 }
4424 }
4426 /* If EXP is a constant, we can evaluate whether this is true or false. */
4428 {
4435 }
4439 }
4440 \f
4441 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4442 type, TYPE, return an expression to test if EXP is in (or out of, depending
4443 on IN_P) the range. Return 0 if the test couldn't be created. */
4445 tree
4448 {
4451 /* Disable this optimization for function pointer expressions
4452 on targets that require function pointer canonicalization. */
4459 {
4465 }
4483 {
4485 {
4489 }
4491 }
4493 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4495 {
4499 {
4501 {
4504 etype
4506 else
4509 }
4512 }
4513 }
4515 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4516 This requires wrap-around arithmetics for the type of the expression.
4517 First make sure that arithmetics in this type is valid, then make sure
4518 that it wraps around. */
4524 {
4527 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4528 for the type in question, as we rely on this here. */
4538 else
4540 }
4550 {
4552 {
4557 }
4559 }
4567 }
4568 \f
4569 /* Return the predecessor of VAL in its type, handling the infinite case. */
4571 static tree
4573 {
4579 else
4582 }
4584 /* Return the successor of VAL in its type, handling the infinite case. */
4586 static tree
4588 {
4594 else
4597 }
4599 /* Given two ranges, see if we can merge them into one. Return 1 if we
4600 can, 0 if we can't. Set the output range into the specified parameters. */
4602 bool
4605 {
4609 tree tem;
4619 /* Make range 0 be the range that starts first, or ends last if they
4620 start at the same value. Swap them if it isn't. */
4623 || (lowequal
4626 {
4630 }
4632 /* Now flag two cases, whether the ranges are disjoint or whether the
4633 second range is totally subsumed in the first. Note that the tests
4634 below are simplified by the ones above. */
4640 /* We now have four cases, depending on whether we are including or
4641 excluding the two ranges. */
4643 {
4644 /* If they don't overlap, the result is false. If the second range
4645 is a subset it is the result. Otherwise, the range is from the start
4646 of the second to the end of the first. */
4651 else
4653 }
4656 {
4657 /* If they don't overlap, the result is the first range. If they are
4658 equal, the result is false. If the second range is a subset of the
4659 first, and the ranges begin at the same place, we go from just after
4660 the end of the second range to the end of the first. If the second
4661 range is not a subset of the first, or if it is a subset and both
4662 ranges end at the same place, the range starts at the start of the
4663 first range and ends just before the second range.
4664 Otherwise, we can't describe this as a single range. */
4670 {
4675 {
4676 /* We are in the weird situation where high0 > high1 but
4677 high1 has no successor. Punt. */
4679 }
4680 }
4682 {
4687 {
4688 /* low0 < low1 but low1 has no predecessor. Punt. */
4690 }
4691 }
4692 else
4694 }
4697 {
4698 /* If they don't overlap, the result is the second range. If the second
4699 is a subset of the first, the result is false. Otherwise,
4700 the range starts just after the first range and ends at the
4701 end of the second. */
4706 else
4707 {
4712 {
4713 /* high1 > high0 but high0 has no successor. Punt. */
4715 }
4716 }
4717 }
4719 else
4720 {
4721 /* The case where we are excluding both ranges. Here the complex case
4722 is if they don't overlap. In that case, the only time we have a
4723 range is if they are adjacent. If the second is a subset of the
4724 first, the result is the first. Otherwise, the range to exclude
4725 starts at the beginning of the first range and ends at the end of the
4726 second. */
4728 {
4733 else
4734 {
4735 /* Canonicalize - [min, x] into - [-, x]. */
4738 {
4743 /* FALLTHROUGH */
4756 }
4758 /* Canonicalize - [x, max] into - [x, -]. */
4761 {
4766 /* FALLTHROUGH */
4782 }
4784 /* The ranges might be also adjacent between the maximum and
4785 minimum values of the given type. For
4786 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4787 return + [x + 1, y - 1]. */
4789 {
4796 }
4797 else
4799 }
4800 }
4803 else
4805 }
4809 }
4810 \f
4812 /* Subroutine of fold, looking inside expressions of the form
4813 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4814 of the COND_EXPR. This function is being used also to optimize
4815 A op B ? C : A, by reversing the comparison first.
4817 Return a folded expression whose code is not a COND_EXPR
4818 anymore, or NULL_TREE if no folding opportunity is found. */
4820 static tree
4823 {
4828 tree tem;
4833 /* If we have A op 0 ? A : -A, consider applying the following
4834 transformations:
4836 A == 0? A : -A same as -A
4837 A != 0? A : -A same as A
4838 A >= 0? A : -A same as abs (A)
4839 A > 0? A : -A same as abs (A)
4840 A <= 0? A : -A same as -abs (A)
4841 A < 0? A : -A same as -abs (A)
4843 None of these transformations work for modes with signed
4844 zeros. If A is +/-0, the first two transformations will
4845 change the sign of the result (from +0 to -0, or vice
4846 versa). The last four will fix the sign of the result,
4847 even though the original expressions could be positive or
4848 negative, depending on the sign of A.
4850 Note that all these transformations are correct if A is
4851 NaN, since the two alternatives (A and -A) are also NaNs. */
4858 /* In the case that A is of the form X-Y, '-A' (arg2) may
4859 have already been folded to Y-X, check for that. */
4867 {
4881 /* Fall through. */
4903 }
4905 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4906 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4907 both transformations are correct when A is NaN: A != 0
4908 is then true, and A == 0 is false. */
4912 {
4917 }
4919 /* Try some transformations of A op B ? A : B.
4921 A == B? A : B same as B
4922 A != B? A : B same as A
4923 A >= B? A : B same as max (A, B)
4924 A > B? A : B same as max (B, A)
4925 A <= B? A : B same as min (A, B)
4926 A < B? A : B same as min (B, A)
4928 As above, these transformations don't work in the presence
4929 of signed zeros. For example, if A and B are zeros of
4930 opposite sign, the first two transformations will change
4931 the sign of the result. In the last four, the original
4932 expressions give different results for (A=+0, B=-0) and
4933 (A=-0, B=+0), but the transformed expressions do not.
4935 The first two transformations are correct if either A or B
4936 is a NaN. In the first transformation, the condition will
4937 be false, and B will indeed be chosen. In the case of the
4938 second transformation, the condition A != B will be true,
4939 and A will be chosen.
4941 The conversions to max() and min() are not correct if B is
4942 a number and A is not. The conditions in the original
4943 expressions will be false, so all four give B. The min()
4944 and max() versions would give a NaN instead. */
4947 /* Avoid these transformations if the COND_EXPR may be used
4948 as an lvalue in the C++ front-end. PR c++/19199. */
4949 && (in_gimple_form
4955 {
4960 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4962 {
4966 }
4969 {
4978 /* In C++ a ?: expression can be an lvalue, so put the
4979 operand which will be used if they are equal first
4980 so that we can convert this back to the
4981 corresponding COND_EXPR. */
4983 {
4992 }
4999 {
5008 }
5023 }
5024 }
5026 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5027 we might still be able to simplify this. For example,
5028 if C1 is one less or one more than C2, this might have started
5029 out as a MIN or MAX and been transformed by this function.
5030 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5036 {
5040 /* We can replace A with C1 in this case. */
5045 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5046 MIN_EXPR, to preserve the signedness of the comparison. */
5048 OEP_ONLY_CONST)
5052 OEP_ONLY_CONST))
5053 {
5056 arg2));
5059 }
5063 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5064 as above. */
5066 OEP_ONLY_CONST)
5070 OEP_ONLY_CONST))
5071 {
5074 arg2));
5077 }
5081 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5082 MAX_EXPR, to preserve the signedness of the comparison. */
5084 OEP_ONLY_CONST)
5088 OEP_ONLY_CONST))
5089 {
5092 arg2));
5094 }
5098 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5100 OEP_ONLY_CONST)
5104 OEP_ONLY_CONST))
5105 {
5108 arg2));
5110 }
5116 }
5119 }
5122 \f
5123 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5124 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5125 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5126 false) >= 2)
5127 #endif
5129 /* EXP is some logical combination of boolean tests. See if we can
5130 merge it into some range test. Return the new tree if so. */
5132 static tree
5135 {
5151 /* If this is an OR operation, invert both sides; we will invert
5152 again at the end. */
5156 /* If both expressions are the same, if we can merge the ranges, and we
5157 can build the range test, return it or it inverted. If one of the
5158 ranges is always true or always false, consider it to be the same
5159 expression as the other. */
5167 {
5171 }
5173 /* On machines where the branch cost is expensive, if this is a
5174 short-circuited branch and the underlying object on both sides
5175 is the same, make a non-short-circuit operation. */
5181 {
5182 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5183 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5184 which cases we can't do this. */
5192 {
5201 {
5204 WARN_STRICT_OVERFLOW_COMPARISON);
5208 }
5209 }
5210 }
5213 }
5214 \f
5215 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5216 bit value. Arrange things so the extra bits will be set to zero if and
5217 only if C is signed-extended to its full width. If MASK is nonzero,
5218 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5220 static tree
5222 {
5225 tree temp;
5230 /* We work by getting just the sign bit into the low-order bit, then
5231 into the high-order bit, then sign-extend. We then XOR that value
5232 with C. */
5235 /* We must use a signed type in order to get an arithmetic right shift.
5236 However, we must also avoid introducing accidental overflows, so that
5237 a subsequent call to integer_zerop will work. Hence we must
5238 do the type conversion here. At this point, the constant is either
5239 zero or one, and the conversion to a signed type can never overflow.
5240 We could get an overflow if this conversion is done anywhere else. */
5249 /* If necessary, convert the type back to match the type of C. */
5254 }
5255 \f
5256 /* For an expression that has the form
5257 (A && B) || ~B
5258 or
5259 (A || B) && ~B,
5260 we can drop one of the inner expressions and simplify to
5261 A || ~B
5262 or
5263 A && ~B
5264 LOC is the location of the resulting expression. OP is the inner
5265 logical operation; the left-hand side in the examples above, while CMPOP
5266 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5267 removing a condition that guards another, as in
5268 (A != NULL && A->...) || A == NULL
5269 which we must not transform. If RHS_ONLY is true, only eliminate the
5270 right-most operand of the inner logical operation. */
5272 static tree
5275 {
5293 {
5296 {
5299 }
5300 }
5302 {
5305 {
5308 }
5309 }
5324 }
5326 /* Find ways of folding logical expressions of LHS and RHS:
5327 Try to merge two comparisons to the same innermost item.
5328 Look for range tests like "ch >= '0' && ch <= '9'".
5329 Look for combinations of simple terms on machines with expensive branches
5330 and evaluate the RHS unconditionally.
5332 For example, if we have p->a == 2 && p->b == 4 and we can make an
5333 object large enough to span both A and B, we can do this with a comparison
5334 against the object ANDed with the a mask.
5336 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5337 operations to do this with one comparison.
5339 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5340 function and the one above.
5342 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5343 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5345 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5346 two operands.
5348 We return the simplified tree or 0 if no optimization is possible. */
5350 static tree
5353 {
5354 /* If this is the "or" of two comparisons, we can do something if
5355 the comparisons are NE_EXPR. If this is the "and", we can do something
5356 if the comparisons are EQ_EXPR. I.e.,
5357 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5359 WANTED_CODE is this operation code. For single bit fields, we can
5360 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5361 comparison for one-bit fields. */
5381 /* Start by getting the comparison codes. Fail if anything is volatile.
5382 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5383 it were surrounded with a NE_EXPR. */
5392 {
5396 }
5399 {
5403 }
5414 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5417 {
5420 {
5425 }
5428 {
5434 }
5435 }
5440 /* If the RHS can be evaluated unconditionally and its operands are
5441 simple, it wins to evaluate the RHS unconditionally on machines
5442 with expensive branches. In this case, this isn't a comparison
5443 that can be merged. */
5450 {
5451 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5462 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5472 }
5474 /* See if the comparisons can be merged. Then get all the parameters for
5475 each side. */
5499 /* It must be true that the inner operation on the lhs of each
5500 comparison must be the same if we are to be able to do anything.
5501 Then see if we have constants. If not, the same must be true for
5502 the rhs's. */
5513 else
5516 /* If either comparison code is not correct for our logical operation,
5517 fail. However, we can convert a one-bit comparison against zero into
5518 the opposite comparison against that bit being set in the field. */
5522 {
5524 {
5525 /* Make the left operand unsigned, since we are only interested
5526 in the value of one bit. Otherwise we are doing the wrong
5527 thing below. */
5530 }
5531 else
5533 }
5535 /* This is analogous to the code for l_const above. */
5537 {
5539 {
5542 }
5543 else
5545 }
5547 /* See if we can find a mode that contains both fields being compared on
5548 the left. If we can't, fail. Otherwise, update all constants and masks
5549 to be relative to a field of that size. */
5554 volatilep);
5564 {
5567 }
5575 {
5582 {
5586 }
5587 }
5589 {
5596 {
5600 }
5601 }
5603 /* If the right sides are not constant, do the same for it. Also,
5604 disallow this optimization if a size or signedness mismatch occurs
5605 between the left and right sides. */
5607 {
5610 /* Make sure the two fields on the right
5611 correspond to the left without being swapped. */
5619 volatilep);
5629 {
5632 }
5641 /* Make a mask that corresponds to both fields being compared.
5642 Do this for both items being compared. If the operands are the
5643 same size and the bits being compared are in the same position
5644 then we can do this by masking both and comparing the masked
5645 results. */
5649 {
5661 }
5663 /* There is still another way we can do something: If both pairs of
5664 fields being compared are adjacent, we may be able to make a wider
5665 field containing them both.
5667 Note that we still must mask the lhs/rhs expressions. Furthermore,
5668 the mask must be shifted to account for the shift done by
5669 make_bit_field_ref. */
5674 {
5675 tree type;
5689 /* Convert to the smaller type before masking out unwanted bits. */
5692 {
5694 {
5698 }
5700 {
5704 }
5705 }
5714 }
5717 }
5719 /* Handle the case of comparisons with constants. If there is something in
5720 common between the masks, those bits of the constants must be the same.
5721 If not, the condition is always false. Test for this to avoid generating
5722 incorrect code below. */
5727 {
5729 {
5732 }
5733 else
5734 {
5737 }
5738 }
5740 /* Construct the expression we will return. First get the component
5741 reference we will make. Unless the mask is all ones the width of
5742 that field, perform the mask operation. Then compare with the
5743 merged constant. */
5753 }
5754 \f
5755 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5756 constant. */
5758 static tree
5761 {
5764 tree comp_const;
5765 tree minmax_const;
5767 tree inner;
5778 /* If something does not permit us to optimize, return the original tree. */
5786 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5787 and GT_EXPR, doing the rest with recursive calls using logical
5788 simplifications. */
5790 {
5792 {
5793 tree tem
5800 }
5803 return
5805 optimize_minmax_comparison
5807 optimize_minmax_comparison
5812 /* MAX (X, 0) == 0 -> X <= 0 */
5816 /* MAX (X, 0) == 5 -> X == 5 */
5820 /* MAX (X, 0) == -1 -> false */
5824 /* MIN (X, 0) == 0 -> X >= 0 */
5828 /* MIN (X, 0) == 5 -> false */
5831 else
5832 /* MIN (X, 0) == -1 -> X == -1 */
5837 /* MAX (X, 0) > 0 -> X > 0
5838 MAX (X, 0) > 5 -> X > 5 */
5842 /* MAX (X, 0) > -1 -> true */
5846 /* MIN (X, 0) > 0 -> false
5847 MIN (X, 0) > 5 -> false */
5850 else
5851 /* MIN (X, 0) > -1 -> X > -1 */
5856 }
5857 }
5858 \f
5859 /* T is an integer expression that is being multiplied, divided, or taken a
5860 modulus (CODE says which and what kind of divide or modulus) by a
5861 constant C. See if we can eliminate that operation by folding it with
5862 other operations already in T. WIDE_TYPE, if non-null, is a type that
5863 should be used for the computation if wider than our type.
5865 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5866 (X * 2) + (Y * 4). We must, however, be assured that either the original
5867 expression would not overflow or that overflow is undefined for the type
5868 in the language in question.
5870 If we return a non-null expression, it is an equivalent form of the
5871 original computation, but need not be in the original type.
5873 We set *STRICT_OVERFLOW_P to true if the return values depends on
5874 signed overflow being undefined. Otherwise we do not change
5875 *STRICT_OVERFLOW_P. */
5877 static tree
5880 {
5881 /* To avoid exponential search depth, refuse to allow recursion past
5882 three levels. Beyond that (1) it's highly unlikely that we'll find
5883 something interesting and (2) we've probably processed it before
5884 when we built the inner expression. */
5887 tree ret;
5892 depth++;
5894 depth--;
5897 }
5899 static tree
5902 {
5913 /* Don't deal with constants of zero here; they confuse the code below. */
5923 /* Note that we need not handle conditional operations here since fold
5924 already handles those cases. So just do arithmetic here. */
5926 {
5928 /* For a constant, we can always simplify if we are a multiply
5929 or (for divide and modulus) if it is a multiple of our constant. */
5937 /* If op0 is an expression ... */
5943 /* ... and has wrapping overflow, and its type is smaller
5944 than ctype, then we cannot pass through as widening. */
5949 /* ... or this is a truncation (t is narrower than op0),
5950 then we cannot pass through this narrowing. */
5953 /* ... or signedness changes for division or modulus,
5954 then we cannot pass through this conversion. */
5958 /* ... or has undefined overflow while the converted to
5959 type has not, we cannot do the operation in the inner type
5960 as that would introduce undefined overflow. */
5966 /* Pass the constant down and see if we can make a simplification. If
5967 we can, replace this expression with the inner simplification for
5968 possible later conversion to our or some other type. */
5973 code == MULT_EXPR
5975 strict_overflow_p))))
5980 /* If widening the type changes it from signed to unsigned, then we
5981 must avoid building ABS_EXPR itself as unsigned. */
5983 {
5987 {
5990 }
5992 }
5993 /* If the constant is negative, we cannot simplify this. */
5996 /* FALLTHROUGH */
5998 /* For division and modulus, type can't be unsigned, as e.g.
5999 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6000 For signed types, even with wrapping overflow, this is fine. */
6009 /* If widening the type changes the signedness, then we can't perform
6010 this optimization as that changes the result. */
6014 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6020 {
6027 }
6031 /* If the second operand is constant, this is a multiplication
6032 or floor division, by a power of two, so we can treat it that
6033 way unless the multiplier or divisor overflows. Signed
6034 left-shift overflow is implementation-defined rather than
6035 undefined in C90, so do not convert signed left shift into
6036 multiplication. */
6039 /* const_binop may not detect overflow correctly,
6040 so check for it explicitly here. */
6044 size_one_node,
6045 op1)))
6049 ctype,
6051 t1),
6056 /* See if we can eliminate the operation on both sides. If we can, we
6057 can return a new PLUS or MINUS. If we can't, the only remaining
6058 cases where we can do anything are if the second operand is a
6059 constant. */
6065 /* If not multiplication, we can only do this if both operands
6066 are divisible by c. */
6069 {
6074 }
6076 /* If this was a subtraction, negate OP1 and set it to be an addition.
6077 This simplifies the logic below. */
6079 {
6081 /* If OP1 was not easily negatable, the constant may be OP0. */
6083 {
6086 }
6087 }
6092 /* If either OP1 or C are negative, this optimization is not safe for
6093 some of the division and remainder types while for others we need
6094 to change the code. */
6096 {
6104 }
6106 /* If it's a multiply or a division/modulus operation of a multiple
6107 of our constant, do the operation and verify it doesn't overflow. */
6110 {
6113 /* We allow the constant to overflow with wrapping semantics. */
6117 }
6118 else
6121 /* If we have an unsigned type, we cannot widen the operation since it
6122 will change the result if the original computation overflowed. */
6126 /* If we were able to eliminate our operation from the first side,
6127 apply our operation to the second side and reform the PLUS. */
6131 /* The last case is if we are a multiply. In that case, we can
6132 apply the distributive law to commute the multiply and addition
6133 if the multiplication of the constants doesn't overflow
6134 and overflow is defined. With undefined overflow
6135 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6141 op1);
6146 /* We have a special case here if we are doing something like
6147 (C * 8) % 4 since we know that's zero. */
6150 /* If the multiplication can overflow we cannot optimize this. */
6154 {
6157 }
6159 /* ... fall through ... */
6163 /* If we can extract our operation from the LHS, do so and return a
6164 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6165 do something only if the second operand is a constant. */
6179 /* If these are the same operation types, we can associate them
6180 assuming no overflow. */
6182 {
6192 {
6197 }
6198 }
6200 /* If these operations "cancel" each other, we have the main
6201 optimizations of this pass, which occur when either constant is a
6202 multiple of the other, in which case we replace this with either an
6203 operation or CODE or TCODE.
6205 If we have an unsigned type, we cannot do this since it will change
6206 the result if the original computation overflowed. */
6213 {
6215 {
6222 }
6224 {
6231 }
6232 }
6237 }
6240 }
6241 \f
6242 /* Return a node which has the indicated constant VALUE (either 0 or
6243 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6244 and is of the indicated TYPE. */
6246 tree
6248 {
6257 else
6259 }
6262 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6263 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6264 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6265 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6266 COND is the first argument to CODE; otherwise (as in the example
6267 given here), it is the second argument. TYPE is the type of the
6268 original expression. Return NULL_TREE if no simplification is
6269 possible. */
6271 static tree
6276 {
6286 {
6290 /* If this operand throws an expression, then it does not make
6291 sense to try to perform a logical or arithmetic operation
6292 involving it. */
6297 }
6298 else
6299 {
6304 }
6309 /* This transformation is only worthwhile if we don't have to wrap ARG
6310 in a SAVE_EXPR and the operation can be simplified without recursing
6311 on at least one of the branches once its pushed inside the COND_EXPR. */
6320 {
6324 else
6326 }
6328 {
6332 else
6334 }
6336 /* Check that we have simplified at least one of the branches. */
6341 }
6343 \f
6344 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6346 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6347 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6348 ADDEND is the same as X.
6350 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6351 and finite. The problematic cases are when X is zero, and its mode
6352 has signed zeros. In the case of rounding towards -infinity,
6353 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6354 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6356 bool
6358 {
6362 /* Don't allow the fold with -fsignaling-nans. */
6366 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6370 /* In a vector or complex, we would need to check the sign of all zeros. */
6374 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6378 /* The mode has signed zeros, and we have to honor their sign.
6379 In this situation, there is only one case we can return true for.
6380 X - 0 is the same as X unless rounding towards -infinity is
6381 supported. */
6383 }
6385 /* Subroutine of fold() that optimizes comparisons of a division by
6386 a nonzero integer constant against an integer constant, i.e.
6387 X/C1 op C2.
6389 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6390 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6391 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6393 The function returns the constant folded tree if a simplification
6394 can be made, and NULL_TREE otherwise. */
6396 static tree
6399 {
6407 /* We have to do this the hard way to detect unsigned overflow.
6408 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6414 {
6419 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6423 }
6425 {
6429 {
6448 }
6449 }
6450 else
6451 {
6452 /* A negative divisor reverses the relational operators. */
6458 {
6477 }
6478 }
6481 {
6502 {
6505 }
6510 {
6513 }
6518 {
6521 }
6526 {
6529 }
6534 }
6537 }
6540 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6541 equality/inequality test, then return a simplified form of the test
6542 using a sign testing. Otherwise return NULL. TYPE is the desired
6543 result type. */
6545 static tree
6548 tree result_type)
6549 {
6550 /* If this is testing a single bit, we can optimize the test. */
6554 {
6555 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6556 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6560 /* This is only a win if casting to a signed type is cheap,
6561 i.e. when arg00's type is not a partial mode. */
6564 {
6567 result_type,
6570 }
6571 }
6574 }
6576 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6577 equality/inequality test, then return a simplified form of
6578 the test using shifts and logical operations. Otherwise return
6579 NULL. TYPE is the desired result type. */
6581 tree
6584 {
6585 /* If this is testing a single bit, we can optimize the test. */
6589 {
6598 /* First, see if we can fold the single bit test into a sign-bit
6599 test. */
6601 result_type);
6605 /* Otherwise we have (A & C) != 0 where C is a single bit,
6606 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6607 Similarly for (A & C) == 0. */
6609 /* If INNER is a right shift of a constant and it plus BITNUM does
6610 not overflow, adjust BITNUM and INNER. */
6616 {
6619 }
6621 /* If we are going to be able to omit the AND below, we must do our
6622 operations as unsigned. If we must use the AND, we have a choice.
6623 Normally unsigned is faster, but for some machines signed is. */
6641 /* Put the AND last so it can combine with more things. */
6644 /* Make sure to return the proper type. */
6648 }
6650 }
6652 /* Check whether we are allowed to reorder operands arg0 and arg1,
6653 such that the evaluation of arg1 occurs before arg0. */
6655 static bool
6657 {
6664 }
6666 /* Test whether it is preferable two swap two operands, ARG0 and
6667 ARG1, for example because ARG0 is an integer constant and ARG1
6668 isn't. If REORDER is true, only recommend swapping if we can
6669 evaluate the operands in reverse order. */
6671 bool
6673 {
6691 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6692 for commutative and comparison operators. Ensuring a canonical
6693 form allows the optimizers to find additional redundancies without
6694 having to explicitly check for both orderings. */
6700 /* Put SSA_NAMEs last. */
6706 /* Put variables last. */
6713 }
6716 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6717 means A >= Y && A != MAX, but in this case we know that
6718 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6720 static tree
6722 {
6729 else
6738 {
6741 }
6743 {
6746 }
6747 else
6754 {
6755 /* Convert the pointer types into integer before taking the difference. */
6759 }
6760 else
6767 }
6769 /* Fold a sum or difference of at least one multiplication.
6770 Returns the folded tree or NULL if no simplification could be made. */
6772 static tree
6775 {
6779 /* (A * C) +- (B * C) -> (A+-B) * C.
6780 (A * C) +- A -> A * (C+-1).
6781 We are most concerned about the case where C is a constant,
6782 but other combinations show up during loop reduction. Since
6783 it is not difficult, try all four possibilities. */
6786 {
6789 }
6791 {
6794 }
6795 else
6796 {
6797 /* We cannot generate constant 1 for fract. */
6802 }
6804 {
6807 }
6809 {
6811 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6812 the purpose of this canonicalization. */
6816 {
6819 }
6820 else
6822 }
6823 else
6824 {
6825 /* We cannot generate constant 1 for fract. */
6830 }
6842 /* No identical multiplicands; see if we can find a common
6843 power-of-two factor in non-power-of-two multiplies. This
6844 can help in multi-dimensional array access. */
6847 {
6850 tree maybe_same;
6854 /* Move min of absolute values to int11. */
6856 {
6861 }
6862 else
6866 /* The remainder should not be a constant, otherwise we
6867 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6868 increased the number of multiplications necessary. */
6870 {
6878 }
6879 }
6889 }
6891 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6892 specified by EXPR into the buffer PTR of length LEN bytes.
6893 Return the number of bytes placed in the buffer, or zero
6894 upon failure. */
6896 static int
6898 {
6912 {
6914 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
6915 number of bytes. */
6919 {
6926 else
6928 }
6929 else
6934 }
6936 }
6939 /* Subroutine of native_encode_expr. Encode the FIXED_CST
6940 specified by EXPR into the buffer PTR of length LEN bytes.
6941 Return the number of bytes placed in the buffer, or zero
6942 upon failure. */
6944 static int
6946 {
6950 FIXED_VALUE_TYPE value;
6966 }
6969 /* Subroutine of native_encode_expr. Encode the REAL_CST
6970 specified by EXPR into the buffer PTR of length LEN bytes.
6971 Return the number of bytes placed in the buffer, or zero
6972 upon failure. */
6974 static int
6976 {
6982 /* There are always 32 bits in each long, no matter the size of
6983 the hosts long. We handle floating point representations with
6984 up to 192 bits. */
6998 {
7003 {
7010 else
7012 }
7013 else
7019 }
7021 }
7023 /* Subroutine of native_encode_expr. Encode the COMPLEX_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 {
7032 tree part;
7047 }
7050 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7051 specified by EXPR into the buffer PTR of length LEN bytes.
7052 Return the number of bytes placed in the buffer, or zero
7053 upon failure. */
7055 static int
7057 {
7067 {
7069 {
7072 }
7083 }
7085 }
7088 /* Subroutine of native_encode_expr. Encode the STRING_CST
7089 specified by EXPR into the buffer PTR of length LEN bytes.
7090 Return the number of bytes placed in the buffer, or zero
7091 upon failure. */
7093 static int
7095 {
7097 HOST_WIDE_INT total_bytes;
7111 {
7114 {
7117 }
7120 }
7121 else
7124 }
7127 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7128 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7129 buffer PTR of length LEN bytes. If OFF is not -1 then start
7130 the encoding at byte offset OFF and encode at most LEN bytes.
7131 Return the number of bytes placed in the buffer, or zero upon failure. */
7133 int
7135 {
7136 /* We don't support starting at negative offset and -1 is special. */
7141 {
7162 }
7163 }
7166 /* Subroutine of native_interpret_expr. Interpret the contents of
7167 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7168 If the buffer cannot be interpreted, return NULL_TREE. */
7170 static tree
7172 {
7182 }
7185 /* Subroutine of native_interpret_expr. Interpret the contents of
7186 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7187 If the buffer cannot be interpreted, return NULL_TREE. */
7189 static tree
7191 {
7193 double_int result;
7194 FIXED_VALUE_TYPE fixed_value;
7204 }
7207 /* Subroutine of native_interpret_expr. Interpret the contents of
7208 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7209 If the buffer cannot be interpreted, return NULL_TREE. */
7211 static tree
7213 {
7217 /* There are always 32 bits in each long, no matter the size of
7218 the hosts long. We handle floating point representations with
7219 up to 192 bits. */
7220 REAL_VALUE_TYPE r;
7231 {
7232 /* Both OFFSET and BYTE index within a long;
7233 bitpos indexes the whole float. */
7236 {
7243 else
7245 }
7246 else
7247 {
7250 {
7251 /* Reverse bytes within each long, or within the entire float
7252 if it's smaller than a long (for HFmode). */
7255 }
7256 }
7260 }
7264 }
7267 /* Subroutine of native_interpret_expr. Interpret the contents of
7268 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7269 If the buffer cannot be interpreted, return NULL_TREE. */
7271 static tree
7273 {
7288 }
7291 /* Subroutine of native_interpret_expr. Interpret the contents of
7292 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7293 If the buffer cannot be interpreted, return NULL_TREE. */
7295 static tree
7297 {
7310 {
7315 }
7317 }
7320 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7321 the buffer PTR of length LEN as a constant of type TYPE. For
7322 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7323 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7324 return NULL_TREE. */
7326 tree
7328 {
7330 {
7352 }
7353 }
7355 /* Returns true if we can interpret the contents of a native encoding
7356 as TYPE. */
7358 static bool
7360 {
7362 {
7375 }
7376 }
7378 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7379 TYPE at compile-time. If we're unable to perform the conversion
7380 return NULL_TREE. */
7382 static tree
7384 {
7385 /* We support up to 512-bit values (for V8DFmode). */
7389 /* Check that the host and target are sane. */
7398 }
7400 /* Build an expression for the address of T. Folds away INDIRECT_REF
7401 to avoid confusing the gimplify process. */
7403 tree
7405 {
7406 /* The size of the object is not relevant when talking about its address. */
7411 {
7416 }
7426 {
7431 }
7432 else
7436 }
7438 /* Build an expression for the address of T. */
7440 tree
7442 {
7446 }
7448 /* Fold a unary expression of code CODE and type TYPE with operand
7449 OP0. Return the folded expression if folding is successful.
7450 Otherwise, return NULL_TREE. */
7452 tree
7454 {
7455 tree tem;
7456 tree arg0;
7464 {
7467 {
7468 /* Don't use STRIP_NOPS, because signedness of argument type
7469 matters. */
7471 }
7472 else
7473 {
7474 /* Strip any conversions that don't change the mode. This
7475 is safe for every expression, except for a comparison
7476 expression because its signedness is derived from its
7477 operands.
7479 Note that this is done as an internal manipulation within
7480 the constant folder, in order to find the simplest
7481 representation of the arguments so that their form can be
7482 studied. In any cases, the appropriate type conversions
7483 should be put back in the tree that will get out of the
7484 constant folder. */
7486 }
7489 {
7492 {
7496 }
7497 }
7498 }
7505 {
7512 {
7526 /* If this was a conversion, and all we did was to move into
7527 inside the COND_EXPR, bring it back out. But leave it if
7528 it is a conversion from integer to integer and the
7529 result precision is no wider than a word since such a
7530 conversion is cheap and may be optimized away by combine,
7531 while it couldn't if it were outside the COND_EXPR. Then return
7532 so we don't get into an infinite recursion loop taking the
7533 conversion out and then back in. */
7545 && (INTEGRAL_TYPE_P
7558 }
7559 }
7562 {
7568 CASE_CONVERT:
7572 {
7573 /* If we have (type) (a CMP b) and type is an integral type, return
7574 new expression involving the new type. Canonicalize
7575 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7576 non-integral type.
7577 Do not fold the result as that would not simplify further, also
7578 folding again results in recursions. */
7588 }
7590 /* Handle (T *)&A.B.C for A being of type T and B and C
7591 living at offset zero. This occurs frequently in
7592 C++ upcasting and then accessing the base. */
7596 {
7598 tree offset;
7599 machine_mode mode;
7604 /* If the reference was to a (constant) zero offset, we can use
7605 the address of the base if it has the same base type
7606 as the result type and the pointer type is unqualified. */
7613 }
7617 /* Detect assigning a bitfield. */
7619 && DECL_BIT_FIELD
7621 {
7622 /* Don't leave an assignment inside a conversion
7623 unless assigning a bitfield. */
7625 /* First do the assignment, then return converted constant. */
7630 }
7632 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7633 constants (if x has signed type, the sign bit cannot be set
7634 in c). This folds extension into the BIT_AND_EXPR.
7635 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7636 very likely don't have maximal range for their precision and this
7637 transformation effectively doesn't preserve non-maximal ranges. */
7641 {
7652 <= HOST_BITS_PER_WIDE_INT
7654 {
7658 cst &= HOST_WIDE_INT_M1U
7662 && !flag_syntax_only
7665 {
7669 }
7670 }
7672 {
7677 }
7678 }
7680 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7681 when one of the new casts will fold away. Conservatively we assume
7682 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7689 {
7693 return fold_build_pointer_plus_loc
7695 }
7697 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7698 of the same precision, and X is an integer type not narrower than
7699 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7705 {
7711 }
7713 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7714 type of X and Y (integer types only). */
7719 {
7720 /* Be careful not to introduce new overflows. */
7721 tree mult_type;
7724 else
7728 {
7735 }
7736 }
7754 /* Convert fabs((double)float) into (double)fabsf(float). */
7757 {
7763 targ0));
7764 }
7766 /* Strip sign ops from argument. */
7768 {
7773 }
7777 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7796 /* Note that the operand of this must be an int
7797 and its values must be 0 or 1.
7798 ("true" is a fixed value perhaps depending on the language,
7799 but we don't handle values other than 1 correctly yet.) */
7806 /* Fold *&X to X if X is an lvalue. */
7808 {
7815 }
7821 }
7824 /* If the operation was a conversion do _not_ mark a resulting constant
7825 with TREE_OVERFLOW if the original constant was not. These conversions
7826 have implementation defined behavior and retaining the TREE_OVERFLOW
7827 flag here would confuse later passes such as VRP. */
7828 tree
7831 {
7840 }
7842 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7843 operands OP0 and OP1. LOC is the location of the resulting expression.
7844 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7845 Return the folded expression if folding is successful. Otherwise,
7846 return NULL_TREE. */
7847 static tree
7850 {
7851 tree tem;
7853 /* We only do these simplifications if we are optimizing. */
7857 /* Check for things like (A || B) && (A || C). We can convert this
7858 to A || (B && C). Note that either operator can be any of the four
7859 truth and/or operations and the transformation will still be
7860 valid. Also note that we only care about order for the
7861 ANDIF and ORIF operators. If B contains side effects, this
7862 might change the truth-value of A. */
7869 {
7889 /* This case if tricky because we must either have commutative
7890 operators or else A10 must not have side-effects. */
7896 a01);
7897 }
7899 /* See if we can build a range comparison. */
7905 {
7909 }
7913 {
7917 }
7919 /* Check for the possibility of merging component references. If our
7920 lhs is another similar operation, try to merge its rhs with our
7921 rhs. Then try to merge our lhs and rhs. */
7935 {
7942 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
7943 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
7944 We don't want to pack more than two leafs to a non-IF AND/OR
7945 expression.
7946 If tree-code of left-hand operand isn't an AND/OR-IF code and not
7947 equal to IF-CODE, then we don't want to add right-hand operand.
7948 If the inner right-hand side of left-hand operand has
7949 side-effects, or isn't simple, then we can't add to it,
7950 as otherwise we might destroy if-sequence. */
7953 /* Needed for sequence points to handle trappings, and
7954 side-effects. */
7956 {
7958 arg1);
7960 tem);
7961 }
7962 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
7963 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
7966 /* Needed for sequence points to handle trappings, and
7967 side-effects. */
7969 {
7974 }
7975 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
7976 into (A OR B).
7977 For sequence point consistancy, we need to check for trapping,
7978 and side-effects. */
7982 }
7985 }
7987 /* Fold a binary expression of code CODE and type TYPE with operands
7988 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
7989 Return the folded expression if folding is successful. Otherwise,
7990 return NULL_TREE. */
7992 static tree
7994 {
8001 else
8004 /* MIN (MAX (a, b), b) == b. */
8009 /* MIN (MAX (b, a), b) == b. */
8015 /* MIN (a, MAX (a, b)) == a. */
8021 /* MIN (a, MAX (b, a)) == a. */
8028 }
8030 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8031 by changing CODE to reduce the magnitude of constants involved in
8032 ARG0 of the comparison.
8033 Returns a canonicalized comparison tree if a simplification was
8034 possible, otherwise returns NULL_TREE.
8035 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8036 valid if signed overflow is undefined. */
8038 static tree
8042 {
8047 /* Match A +- CST code arg1. We can change this only if overflow
8048 is undefined. */
8051 /* In principle pointers also have undefined overflow behavior,
8052 but that causes problems elsewhere. */
8059 /* Identify the constant in arg0 and its sign. */
8063 /* Overflowed constants and zero will cause problems. */
8068 /* See if we can reduce the magnitude of the constant in
8069 arg0 by changing the comparison code. */
8070 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8074 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8078 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8082 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8086 else
8090 /* Now build the constant reduced in magnitude. But not if that
8091 would produce one outside of its types range. */
8107 }
8109 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8110 overflow further. Try to decrease the magnitude of constants involved
8111 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8112 and put sole constants at the second argument position.
8113 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8115 static tree
8118 {
8119 tree t;
8124 /* Try canonicalization by simplifying arg0. */
8129 {
8133 }
8135 /* Try canonicalization by simplifying arg1 using the swapped
8136 comparison. */
8144 }
8146 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8147 space. This is used to avoid issuing overflow warnings for
8148 expressions like &p->x which can not wrap. */
8150 static bool
8152 {
8159 wide_int wi_offset;
8165 else
8181 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8182 array. */
8184 {
8185 HOST_WIDE_INT base_size;
8190 }
8193 }
8195 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8196 kind INTEGER_CST. This makes sure to properly sign-extend the
8197 constant. */
8199 static HOST_WIDE_INT
8201 {
8207 }
8209 /* Subroutine of fold_binary. This routine performs all of the
8210 transformations that are common to the equality/inequality
8211 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8212 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8213 fold_binary should call fold_binary. Fold a comparison with
8214 tree code CODE and type TYPE with operands OP0 and OP1. Return
8215 the folded comparison or NULL_TREE. */
8217 static tree
8220 {
8230 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8232 && (equality_code
8239 {
8240 const enum tree_code
8247 /* If the constant operation overflowed this can be
8248 simplified as a comparison against INT_MAX/INT_MIN. */
8251 {
8255 /* Get the sign of the constant on the lhs if the
8256 operation were VARIABLE + CONST1. */
8260 /* The sign of the constant determines if we overflowed
8261 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8262 Canonicalize to the INT_MIN overflow by swapping the comparison
8263 if necessary. */
8267 /* We now can look at the canonicalized case
8268 VARIABLE + 1 CODE2 INT_MIN
8269 and decide on the result. */
8271 {
8275 return
8281 return
8286 }
8287 }
8288 else
8289 {
8292 "when changing X +- C1 cmp C2 to "
8294 WARN_STRICT_OVERFLOW_COMPARISON);
8296 }
8297 }
8299 /* For comparisons of pointers we can decompose it to a compile time
8300 comparison of the base objects and the offsets into the object.
8301 This requires at least one operand being an ADDR_EXPR or a
8302 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8308 {
8311 machine_mode mode;
8315 /* Get base and offset for the access. Strip ADDR_EXPR for
8316 get_inner_reference, but put it back by stripping INDIRECT_REF
8317 off the base object if possible. indirect_baseN will be true
8318 if baseN is not an address but refers to the object itself. */
8321 {
8327 else
8329 }
8331 {
8335 {
8338 }
8341 {
8346 {
8349 }
8350 }
8351 }
8355 {
8361 else
8363 }
8365 {
8369 {
8372 }
8375 {
8380 {
8383 }
8384 }
8385 }
8387 /* If we have equivalent bases we might be able to simplify. */
8390 {
8391 /* We can fold this expression to a constant if the non-constant
8392 offset parts are equal. */
8401 {
8407 "occur when comparing P +- C1 with "
8409 WARN_STRICT_OVERFLOW_CONDITIONAL);
8412 {
8426 }
8427 }
8428 /* We can simplify the comparison to a comparison of the variable
8429 offset parts if the constant offset parts are equal.
8430 Be careful to use signed sizetype here because otherwise we
8431 mess with array offsets in the wrong way. This is possible
8432 because pointer arithmetic is restricted to retain within an
8433 object and overflow on pointer differences is undefined as of
8434 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8436 && (equality_code
8439 {
8440 /* By converting to signed sizetype we cover middle-end pointer
8441 arithmetic which operates on unsigned pointer types of size
8442 type size and ARRAY_REF offsets which are properly sign or
8443 zero extended from their type in case it is narrower than
8444 sizetype. */
8447 else
8451 else
8458 "occur when comparing P +- C1 with "
8460 WARN_STRICT_OVERFLOW_COMPARISON);
8463 }
8464 }
8465 /* For equal offsets we can simplify to a comparison of the
8466 base addresses. */
8468 && (indirect_base0
8470 && (indirect_base1
8475 {
8481 }
8482 }
8484 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8485 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8486 the resulting offset is smaller in absolute value than the
8487 original one and has the same sign. */
8496 {
8501 tree cst;
8503 "occur when combining constants around "
8506 /* Put the constant on the side where it doesn't overflow and is
8507 of lower absolute value and of same sign than before. */
8514 {
8517 variable1,
8521 }
8529 {
8535 variable2);
8536 }
8537 }
8543 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8544 constant, we can simplify it. */
8549 {
8553 }
8555 /* If we are comparing an expression that just has comparisons
8556 of two integer values, arithmetic expressions of those comparisons,
8557 and constants, we can simplify it. There are only three cases
8558 to check: the two values can either be equal, the first can be
8559 greater, or the second can be greater. Fold the expression for
8560 those three values. Since each value must be 0 or 1, we have
8561 eight possibilities, each of which corresponds to the constant 0
8562 or 1 or one of the six possible comparisons.
8564 This handles common cases like (a > b) == 0 but also handles
8565 expressions like ((x > y) - (y > x)) > 0, which supposedly
8566 occur in macroized code. */
8569 {
8574 /* Don't handle degenerate cases here; they should already
8575 have been handled anyway. */
8584 {
8588 /* We can't just pass T to eval_subst in case cval1 or cval2
8589 was the same as ARG1. */
8591 tree high_result
8595 arg1);
8596 tree equal_result
8600 arg1);
8601 tree low_result
8605 arg1);
8607 /* All three of these results should be 0 or 1. Confirm they are.
8608 Then use those values to select the proper code to use. */
8613 {
8614 /* Make a 3-bit mask with the high-order bit being the
8615 value for `>', the next for '=', and the low for '<'. */
8619 {
8621 /* Always false. */
8642 /* Always true. */
8644 }
8647 {
8651 }
8653 }
8654 }
8655 }
8657 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8658 into a single range test. */
8666 {
8670 }
8673 }
8676 /* Subroutine of fold_binary. Optimize complex multiplications of the
8677 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8678 argument EXPR represents the expression "z" of type TYPE. */
8680 static tree
8682 {
8687 {
8690 }
8692 {
8695 }
8696 else
8697 {
8701 }
8710 }
8713 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8714 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8716 static bool
8718 {
8722 {
8725 }
8727 {
8733 else
8735 }
8736 else
8742 }
8744 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8745 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8746 NULL_TREE otherwise. */
8748 static tree
8750 {
8767 {
8771 }
8774 {
8780 }
8781 else
8783 }
8785 /* Try to fold a pointer difference of type TYPE two address expressions of
8786 array references AREF0 and AREF1 using location LOC. Return a
8787 simplified expression for the difference or NULL_TREE. */
8789 static tree
8792 {
8797 /* If the bases are array references as well, recurse. If the bases
8798 are pointer indirections compute the difference of the pointers.
8799 If the bases are equal, we are set. */
8802 && (base_offset
8810 {
8816 base_offset,
8819 }
8821 }
8823 /* If the real or vector real constant CST of type TYPE has an exact
8824 inverse, return it, else return NULL. */
8826 tree
8828 {
8829 REAL_VALUE_TYPE r;
8831 machine_mode mode;
8835 {
8851 {
8856 }
8862 }
8863 }
8865 /* Mask out the tz least significant bits of X of type TYPE where
8866 tz is the number of trailing zeroes in Y. */
8867 static wide_int
8869 {
8874 }
8876 /* Return true when T is an address and is known to be nonzero.
8877 For floating point we further ensure that T is not denormal.
8878 Similar logic is present in nonzero_address in rtlanal.h.
8880 If the return value is based on the assumption that signed overflow
8881 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8882 change *STRICT_OVERFLOW_P. */
8884 static bool
8886 {
8890 /* Doing something useful for floating point would need more work. */
8896 {
8899 strict_overflow_p);
8905 strict_overflow_p);
8913 }
8916 {
8919 strict_overflow_p);
8927 strict_overflow_p);
8942 strict_overflow_p);
8946 strict_overflow_p);
8949 {
8961 }
8965 }
8967 }
8969 /* Return true when T is an address and is known to be nonzero.
8970 Handle warnings about undefined signed overflow. */
8972 static bool
8974 {
8981 "determining that expression is always "
8983 WARN_STRICT_OVERFLOW_MISC);
8985 }
8987 /* Fold a binary expression of code CODE and type TYPE with operands
8988 OP0 and OP1. LOC is the location of the resulting expression.
8989 Return the folded expression if folding is successful. Otherwise,
8990 return NULL_TREE. */
8992 tree
8995 {
9010 /* Strip any conversions that don't change the mode. This is
9011 safe for every expression, except for a comparison expression
9012 because its signedness is derived from its operands. So, in
9013 the latter case, only strip conversions that don't change the
9014 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9015 preserved.
9017 Note that this is done as an internal manipulation within the
9018 constant folder, in order to find the simplest representation
9019 of the arguments so that their form can be studied. In any
9020 cases, the appropriate type conversions should be put back in
9021 the tree that will get out of the constant folder. */
9024 {
9027 }
9028 else
9029 {
9032 }
9034 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9035 constant but we can't do arithmetic on them. */
9037 {
9040 {
9044 }
9045 }
9047 /* If this is a commutative operation, and ARG0 is a constant, move it
9048 to ARG1 to reduce the number of tests below. */
9053 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9054 to ARG1 to reduce the number of tests below. */
9063 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9065 First check for cases where an arithmetic operation is applied to a
9066 compound, conditional, or comparison operation. Push the arithmetic
9067 operation inside the compound or conditional to see if any folding
9068 can then be done. Convert comparison to conditional for this purpose.
9069 The also optimizes non-constant cases that used to be done in
9070 expand_expr.
9072 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9073 one of the operands is a comparison and the other is a comparison, a
9074 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9075 code below would make the expression more complex. Change it to a
9076 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9077 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9090 {
9094 boolean_type_node,
9102 }
9106 {
9108 {
9113 tem);
9114 }
9117 {
9122 tem);
9123 }
9128 {
9134 }
9139 {
9145 }
9146 }
9149 {
9151 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9154 {
9160 }
9162 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9165 {
9166 tree base;
9167 HOST_WIDE_INT coffset;
9176 }
9181 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9187 arg1),
9189 arg0)));
9195 {
9196 /* X + (X / CST) * -CST is X % CST. */
9201 {
9210 cst0));
9211 }
9212 }
9214 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9215 one. Make sure the type is not saturating and has the signedness of
9216 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9217 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9224 {
9228 }
9231 {
9232 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9233 (plus (plus (mult) (mult)) (foo)) so that we can
9234 take advantage of the factoring cases below. */
9243 {
9249 else
9262 parg0),
9264 marg)),
9268 return
9274 parg1)));
9275 }
9276 }
9277 else
9278 {
9279 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9280 to __complex__ ( x, y ). This is not the same for SNaNs or
9281 if signed zeros are involved. */
9285 {
9292 {
9296 {
9302 }
9304 {
9310 }
9311 }
9312 }
9320 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9321 We associate floats only if the user has specified
9322 -fassociative-math. */
9326 {
9331 {
9332 tree tree0;
9335 }
9336 }
9337 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9338 We associate floats only if the user has specified
9339 -fassociative-math. */
9343 {
9348 {
9349 tree tree0;
9352 }
9353 }
9354 }
9356 bit_rotate:
9357 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9358 is a rotate of A by C1 bits. */
9359 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9360 is a rotate of A by B bits. */
9361 {
9363 tree rtype;
9372 /* Only create rotates in complete modes. Other cases are not
9373 expanded properly. */
9376 {
9390 {
9394 code0 == LSHIFT_EXPR
9398 }
9400 {
9408 element_precision
9412 return
9415 ? LROTATE_EXPR
9420 }
9422 {
9430 element_precision
9434 return fold_convert_loc
9437 ? LROTATE_EXPR
9441 }
9442 }
9443 }
9445 associate:
9446 /* In most languages, can't associate operations on floats through
9447 parentheses. Rather than remember where the parentheses were, we
9448 don't associate floats at all, unless the user has specified
9449 -fassociative-math.
9450 And, we need to make sure type is not saturating. */
9454 {
9460 /* Split both trees into variables, constants, and literals. Then
9461 associate each group together, the constants with literals,
9462 then the result with variables. This increases the chances of
9463 literals being recombined later and of generating relocatable
9464 expressions for the sum of a constant and literal. */
9469 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9473 /* With undefined overflow prefer doing association in a type
9474 which wraps on overflow, if that is one of the operand types. */
9477 {
9485 }
9487 /* With undefined overflow we can only associate constants with one
9488 variable, and constants whose association doesn't overflow. */
9491 {
9493 {
9511 /* The only case we can still associate with two variables
9512 is if they are the same, modulo negation and bit-pattern
9513 preserving conversions. */
9516 }
9517 }
9519 /* Only do something if we found more than two objects. Otherwise,
9520 nothing has changed and we risk infinite recursion. */
9526 {
9538 /* Preserve the MINUS_EXPR if the negative part of the literal is
9539 greater than the positive part. Otherwise, the multiplicative
9540 folding code (i.e extract_muldiv) may be fooled in case
9541 unsigned constants are subtracted, like in the following
9542 example: ((X*2 + 4) - 8U)/2. */
9544 {
9548 {
9552 }
9553 else
9554 {
9558 }
9559 }
9561 /* Don't introduce overflows through reassociation. */
9568 {
9570 return
9574 else
9575 {
9578 return
9582 }
9583 }
9586 return
9589 }
9590 }
9595 /* Pointer simplifications for subtraction, simple reassociations. */
9597 {
9598 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
9601 {
9611 }
9612 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
9614 {
9621 }
9622 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
9623 simplifies. */
9625 {
9632 arg10);
9635 }
9636 }
9637 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9648 {
9649 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9650 any power of 2 minus 1. */
9655 {
9661 {
9665 }
9666 }
9667 }
9669 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9670 __complex__ ( x, -y ). This is not the same for SNaNs or if
9671 signed zeros are involved. */
9675 {
9682 {
9686 {
9688 arg1r ? arg1r
9693 }
9695 {
9699 arg1i ? arg1i
9702 }
9703 }
9704 }
9706 /* A - B -> A + (-B) if B is easily negatable. */
9710 /* Avoid this transformation if B is a positive REAL_CST. */
9719 /* Fold &a[i] - &a[j] to i-j. */
9724 {
9730 }
9733 && flag_unsafe_math_optimizations
9739 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9740 one. Make sure the type is not saturating and has the signedness of
9741 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9742 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9749 {
9753 }
9758 /* (-A) * (-B) -> A * B */
9773 {
9774 /* Transform x * -C into -x * C if x is easily negatable. */
9783 tem);
9785 /* (a * (1 << b)) is (a << b) */
9795 /* (A + A) * C -> A * 2 * C */
9807 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9808 sign-changing only. */
9818 {
9821 "occur when simplifying "
9823 WARN_STRICT_OVERFLOW_MISC);
9825 }
9827 /* Optimize z * conj(z) for integer complex numbers. */
9834 }
9835 else
9836 {
9837 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
9838 the result for floating point types due to rounding so it is applied
9839 only if -fassociative-math was specify. */
9844 {
9846 arg1);
9850 }
9852 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9854 {
9857 {
9860 }
9861 }
9863 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9864 This is not the same for NaNs or if signed zeros are
9865 involved. */
9871 {
9874 return
9880 return
9885 }
9887 /* Optimize z * conj(z) for floating point complex numbers.
9888 Guarded by flag_unsafe_math_optimizations as non-finite
9889 imaginary components don't produce scalar results. */
9900 {
9902 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
9904 && optimize
9906 {
9910 {
9913 }
9914 }
9915 }
9916 }
9920 /* Canonicalize (X & C1) | C2. */
9924 {
9929 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9937 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9942 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9943 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9944 mode which allows further optimizations. */
9949 {
9953 {
9956 }
9957 }
9964 c3)),
9965 arg1);
9966 }
9968 /* (X & ~Y) | (~X & Y) is X ^ Y */
9971 {
9988 }
9990 /* See if this can be simplified into a rotate first. If that
9991 is unsuccessful continue in the association code. */
9995 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10003 /* See if this can be simplified into a rotate first. If that
10004 is unsuccessful continue in the association code. */
10008 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
10016 /* X & ~X , X & (X == 0), and X & !X are always zero. */
10024 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10029 {
10030 tree tem2;
10037 }
10038 /* Fold ~X & 1 as (X & 1) == 0. */
10042 {
10043 tree tem2;
10050 }
10051 /* Fold !X & 1 as X == 0. */
10054 {
10058 }
10060 /* Fold (X ^ Y) & Y as ~X & Y. */
10063 {
10068 }
10069 /* Fold (X ^ Y) & X as ~Y & X. */
10073 {
10078 }
10079 /* Fold X & (X ^ Y) as X & ~Y. */
10082 {
10087 }
10088 /* Fold X & (Y ^ X) as ~Y & X. */
10092 {
10097 }
10099 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10100 multiple of 1 << CST. */
10102 {
10109 }
10111 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10112 bits from CST2. */
10116 {
10124 {
10125 /* Avoid the transform if arg1 is a mask of some
10126 mode which allows further optimizations. */
10133 }
10134 }
10136 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10137 ((A & N) + B) & M -> (A + B) & M
10138 Similarly if (N & M) == 0,
10139 ((A | N) + B) & M -> (A + B) & M
10140 and for - instead of + (or unary - instead of +)
10141 and/or ^ instead of |.
10142 If B is constant and (B & M) == 0, fold into A & M. */
10144 {
10153 {
10156 wide_int cst0;
10158 /* Now we know that arg0 is (C + D) or (C - D) or
10159 -C and arg1 (M) is == (1LL << cst) - 1.
10160 Store C into PMOP[0] and D into PMOP[1]. */
10164 {
10167 }
10174 {
10184 {
10187 }
10190 /* If C or D is of the form (A & N) where
10191 (N & M) == M, or of the form (A | N) or
10192 (A ^ N) where (N & M) == 0, replace it with A. */
10196 /* If C or D is a N where (N & M) == 0, it can be
10197 omitted (assumed 0). */
10205 }
10207 /* Only build anything new if we optimized one or both arguments
10208 above. */
10212 {
10215 {
10216 /* Perform the operations in a type that has defined
10217 overflow behavior. */
10223 }
10228 {
10236 else
10238 }
10241 else
10244 /* TEM is now the new binary +, - or unary - replacement. */
10248 }
10249 }
10250 }
10252 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10255 {
10260 return
10262 }
10267 /* Don't touch a floating-point divide by zero unless the mode
10268 of the constant can represent infinity. */
10274 /* (-A) / (-B) -> A / B */
10284 /* Convert A/B/C to A/(B*C). */
10291 /* Convert A/(B/C) to (A/B)*C. */
10299 /* Convert C1/(X*C2) into (C1/C2)/X. */
10304 {
10310 }
10315 /* Optimize (X & (-A)) / A where A is a power of 2,
10316 to X >> log2(A) */
10320 {
10328 }
10329 }
10331 /* Fall through */
10334 /* Simplify A / (B << N) where A and B are positive and B is
10335 a power of 2, to A >> (N + log2(B)). */
10340 {
10343 {
10351 WARN_STRICT_OVERFLOW_MISC);
10357 }
10358 }
10360 /* Fall through */
10368 /* Convert -A / -B to A / B when the type is signed and overflow is
10369 undefined. */
10373 {
10376 "when distributing negation across "
10378 WARN_STRICT_OVERFLOW_MISC);
10384 }
10388 {
10391 "when distributing negation across "
10393 WARN_STRICT_OVERFLOW_MISC);
10399 }
10401 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10402 operation, EXACT_DIV_EXPR.
10404 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10405 At one time others generated faster code, it's not clear if they do
10406 after the last round to changes to the DIV code in expmed.c. */
10417 {
10421 WARN_STRICT_OVERFLOW_MISC);
10423 }
10435 {
10439 WARN_STRICT_OVERFLOW_MISC);
10441 }
10449 /* Since negative shift count is not well-defined,
10450 don't try to compute it in the compiler. */
10456 /* If we have a rotate of a bit operation with the rotate count and
10457 the second operand of the bit operation both constant,
10458 permute the two operations. */
10470 /* Two consecutive rotates adding up to the some integer
10471 multiple of the precision of the type can be ignored. */
10494 /* Note that the operands of this must be ints
10495 and their values must be 0 or 1.
10496 ("true" is a fixed value perhaps depending on the language.) */
10497 /* If first arg is constant zero, return it. */
10501 /* If either arg is constant true, drop it. */
10505 /* Preserve sequence points. */
10508 /* If second arg is constant zero, result is zero, but first arg
10509 must be evaluated. */
10512 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10513 case will be handled here. */
10517 /* !X && X is always false. */
10521 /* X && !X is always false. */
10526 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10527 means A >= Y && A != MAX, but in this case we know that
10528 A < X <= MAX. */
10532 {
10540 }
10549 /* Note that the operands of this must be ints
10550 and their values must be 0 or true.
10551 ("true" is a fixed value perhaps depending on the language.) */
10552 /* If first arg is constant true, return it. */
10556 /* If either arg is constant zero, drop it. */
10560 /* Preserve sequence points. */
10563 /* If second arg is constant true, result is true, but we must
10564 evaluate first arg. */
10567 /* Likewise for first arg, but note this only occurs here for
10568 TRUTH_OR_EXPR. */
10572 /* !X || X is always true. */
10576 /* X || !X is always true. */
10581 /* (X && !Y) || (!X && Y) is X ^ Y */
10584 {
10601 }
10610 /* If the second arg is constant zero, drop it. */
10613 /* If the second arg is constant true, this is a logical inversion. */
10615 {
10618 }
10619 /* Identical arguments cancel to zero. */
10623 /* !X ^ X is always true. */
10628 /* X ^ !X is always true. */
10644 /* bool_var != 1 becomes !bool_var. */
10651 /* bool_var == 0 becomes !bool_var. */
10658 /* !exp != 0 becomes !exp */
10663 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10672 {
10676 val,
10680 }
10682 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10689 {
10691 code == NE_EXPR
10694 }
10696 /* If this is an EQ or NE comparison with zero and ARG0 is
10697 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10698 two operations, but the latter can be done in one less insn
10699 on machines that have only two-operand insns or on which a
10700 constant cannot be the first operand. */
10703 {
10708 {
10715 arg1);
10716 }
10719 {
10726 arg1);
10727 }
10728 }
10730 /* If this is an NE or EQ comparison of zero against the result of a
10731 signed MOD operation whose second operand is a power of 2, make
10732 the MOD operation unsigned since it is simpler and equivalent. */
10740 {
10750 }
10752 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10753 C1 is a valid shift constant, and C2 is a power of two, i.e.
10754 a single bit. */
10758 == INTEGER_CST
10761 {
10766 /* Check for a valid shift count. */
10768 {
10772 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10773 can be rewritten as (X & (C2 << C1)) != 0. */
10775 {
10780 }
10781 /* Otherwise, for signed (arithmetic) shifts,
10782 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10783 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10787 /* Otherwise, of unsigned (logical) shifts,
10788 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10789 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10790 else
10794 arg000);
10795 }
10796 }
10798 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10799 Similarly for NE_EXPR. */
10803 {
10807 tree dandnotc
10810 notc);
10814 }
10816 /* If this is a comparison of a field, we may be able to simplify it. */
10819 /* Handle the constant case even without -O
10820 to make sure the warnings are given. */
10822 {
10826 }
10828 /* Optimize comparisons of strlen vs zero to a compare of the
10829 first character of the string vs zero. To wit,
10830 strlen(ptr) == 0 => *ptr == 0
10831 strlen(ptr) != 0 => *ptr != 0
10832 Other cases should reduce to one of these two (or a constant)
10833 due to the return value of strlen being unsigned. */
10836 {
10844 {
10849 }
10850 }
10852 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10853 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10857 {
10862 {
10864 {
10867 }
10870 }
10871 }
10873 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10874 (X & C) == 0 when C is a single bit. */
10879 {
10886 arg1));
10887 }
10889 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10890 constant C is a power of two, i.e. a single bit. */
10897 {
10901 }
10903 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10904 when is C is a power of two, i.e. a single bit. */
10911 {
10917 }
10921 {
10924 }
10926 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10929 {
10942 arg01),
10951 arg01),
10960 arg00),
10969 arg00),
10971 }
10975 {
10982 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10983 operand_equal_p guarantees no side-effects so we don't need
10984 to use omit_one_operand on Z. */
10988 arg10));
10992 arg11));
10996 arg10));
11000 arg11));
11002 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11005 {
11011 }
11012 }
11014 /* Attempt to simplify equality/inequality comparisons of complex
11015 values. Only lower the comparison if the result is known or
11016 can be simplified to a single scalar comparison. */
11021 {
11026 {
11029 }
11030 else
11031 {
11034 }
11037 {
11040 }
11041 else
11042 {
11045 }
11049 {
11051 {
11056 }
11057 else
11058 {
11063 }
11064 }
11068 {
11070 {
11075 }
11076 else
11077 {
11082 }
11083 }
11084 }
11096 /* Transform comparisons of the form X +- C CMP X. */
11103 {
11110 else
11113 /* (X - c) > X becomes false. */
11117 {
11121 "occur when assuming that (X - c) > X "
11123 WARN_STRICT_OVERFLOW_ALL);
11125 }
11127 /* Likewise (X + c) < X becomes false. */
11131 {
11135 "occur when assuming that "
11137 WARN_STRICT_OVERFLOW_ALL);
11139 }
11141 /* Convert (X - c) <= X to true. */
11146 {
11150 "occur when assuming that "
11152 WARN_STRICT_OVERFLOW_ALL);
11154 }
11156 /* Convert (X + c) >= X to true. */
11161 {
11165 "occur when assuming that "
11167 WARN_STRICT_OVERFLOW_ALL);
11169 }
11172 {
11173 /* Convert X + c > X and X - c < X to true for integers. */
11177 {
11180 "not occur when assuming that "
11182 WARN_STRICT_OVERFLOW_ALL);
11184 }
11189 {
11192 "not occur when assuming that "
11194 WARN_STRICT_OVERFLOW_ALL);
11196 }
11198 /* Convert X + c <= X and X - c >= X to false for integers. */
11202 {
11205 "not occur when assuming that "
11207 WARN_STRICT_OVERFLOW_ALL);
11209 }
11214 {
11217 "not occur when assuming that "
11219 WARN_STRICT_OVERFLOW_ALL);
11221 }
11222 }
11223 }
11225 /* If we are comparing an ABS_EXPR with a constant, we can
11226 convert all the cases into explicit comparisons, but they may
11227 well not be faster than doing the ABS and one comparison.
11228 But ABS (X) <= C is a range comparison, which becomes a subtraction
11229 and a comparison, and is probably faster. */
11243 /* Convert ABS_EXPR<x> >= 0 to true. */
11250 {
11253 "when simplifying comparison of "
11255 WARN_STRICT_OVERFLOW_CONDITIONAL);
11258 arg0);
11259 }
11261 /* Convert ABS_EXPR<x> < 0 to false. */
11266 {
11269 "when simplifying comparison of "
11271 WARN_STRICT_OVERFLOW_CONDITIONAL);
11274 arg0);
11275 }
11277 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11278 and similarly for >= into !=. */
11288 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11289 otherwise Y might be >= # of bits in X's type and thus e.g.
11290 (unsigned char) (1 << Y) for Y 15 might be 0.
11291 If the cast is widening, then 1 << Y should have unsigned type,
11292 otherwise if Y is number of bits in the signed shift type minus 1,
11293 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11294 31 might be 0xffffffff80000000. */
11305 {
11311 }
11323 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11324 {
11336 }
11341 /* When pedantic, a compound expression can be neither an lvalue
11342 nor an integer constant expression. */
11345 /* Don't let (0, 0) be null pointer constant. */
11351 /* An ASSERT_EXPR should never be passed to fold_binary. */
11357 }
11359 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11360 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11361 of GOTO_EXPR. */
11363 static tree
11365 {
11367 {
11374 /* ... fall through ... */
11378 }
11379 }
11381 /* Return whether the sub-tree ST contains a label which is accessible from
11382 outside the sub-tree. */
11384 static bool
11386 {
11387 return
11389 }
11391 /* Fold a ternary expression of code CODE and type TYPE with operands
11392 OP0, OP1, and OP2. Return the folded expression if folding is
11393 successful. Otherwise, return NULL_TREE. */
11395 tree
11398 {
11399 tree tem;
11406 /* If this is a commutative operation, and OP0 is a constant, move it
11407 to OP1 to reduce the number of tests below. */
11416 /* Strip any conversions that don't change the mode. This is safe
11417 for every expression, except for a comparison expression because
11418 its signedness is derived from its operands. So, in the latter
11419 case, only strip conversions that don't change the signedness.
11421 Note that this is done as an internal manipulation within the
11422 constant folder, in order to find the simplest representation of
11423 the arguments so that their form can be studied. In any cases,
11424 the appropriate type conversions should be put back in the tree
11425 that will get out of the constant folder. */
11427 {
11430 }
11433 {
11436 }
11439 {
11442 }
11445 {
11449 {
11455 }
11460 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11461 so all simple results must be passed through pedantic_non_lvalue. */
11463 {
11466 /* Only optimize constant conditions when the selected branch
11467 has the same type as the COND_EXPR. This avoids optimizing
11468 away "c ? x : throw", where the throw has a void type.
11469 Avoid throwing away that operand which contains label. */
11476 }
11478 {
11483 {
11488 {
11496 }
11500 }
11501 }
11503 /* If we have A op B ? A : C, we may be able to convert this to a
11504 simpler expression, depending on the operation and the values
11505 of B and C. Signed zeros prevent all of these transformations,
11506 for reasons given above each one.
11508 Also try swapping the arguments and inverting the conditional. */
11513 {
11517 }
11521 op2,
11524 {
11528 {
11532 }
11533 }
11535 /* If the second operand is simpler than the third, swap them
11536 since that produces better jump optimization results. */
11539 {
11541 /* See if this can be inverted. If it can't, possibly because
11542 it was a floating-point inequality comparison, don't do
11543 anything. */
11547 }
11549 /* Convert A ? 1 : 0 to simply A. */
11554 /* If we try to convert OP0 to our type, the
11555 call to fold will try to move the conversion inside
11556 a COND, which will recurse. In that case, the COND_EXPR
11557 is probably the best choice, so leave it alone. */
11561 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11562 over COND_EXPR in cases such as floating point comparisons. */
11571 arg0)));
11573 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11578 {
11579 /* sign_bit_p looks through both zero and sign extensions,
11580 but for this optimization only sign extensions are
11581 usable. */
11584 {
11587 {
11590 }
11592 }
11593 /* sign_bit_p only checks ARG1 bits within A's precision.
11594 If <sign bit of A> has wider type than A, bits outside
11595 of A's precision in <sign bit of A> need to be checked.
11596 If they are all 0, this optimization needs to be done
11597 in unsigned A's type, if they are all 1 in signed A's type,
11598 otherwise this can't be done. */
11604 {
11606 tree tem_type;
11619 {
11622 }
11624 {
11627 }
11628 else
11630 }
11633 return
11639 arg1)));
11640 }
11642 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11643 already handled above. */
11648 {
11657 }
11659 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11660 is probably obsolete because the first operand should be a
11661 truth value (that's why we have the two cases above), but let's
11662 leave it in until we can confirm this for all front-ends. */
11674 /* Disable the transformations below for vectors, since
11675 fold_binary_op_with_conditional_arg may undo them immediately,
11676 yielding an infinite loop. */
11680 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11689 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11694 {
11696 /* Only perform transformation if ARG0 is easily inverted. */
11700 ? BIT_IOR_EXPR
11703 arg1);
11704 }
11706 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11711 {
11713 /* Only perform transformation if ARG0 is easily inverted. */
11719 op2);
11720 }
11722 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11734 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11735 of fold_ternary on them. */
11745 {
11755 {
11760 {
11768 }
11770 /* Constructor elements can be subvectors. */
11773 {
11777 }
11779 /* We keep an exact subset of the constructor elements. */
11781 {
11787 {
11791 }
11799 CONSTRUCTOR_ELT
11802 }
11803 /* The bitfield references a single constructor element. */
11805 {
11810 else
11814 }
11815 }
11816 }
11818 /* A bit-field-ref that referenced the full argument can be stripped. */
11824 /* On constants we can use native encode/interpret to constant
11825 fold (nearly) all BIT_FIELD_REFs. */
11829 /* This limitation should not be necessary, we just need to
11830 round this up to mode size. */
11832 /* Need bit-shifting of the buffer to relax the following. */
11834 {
11839 /* ??? We cannot tell native_encode_expr to start at
11840 some random byte only. So limit us to a reasonable amount
11841 of work. */
11843 {
11848 {
11854 }
11855 }
11856 }
11861 /* For integers we can decompose the FMA if possible. */
11873 {
11889 {
11894 /* Make sure that the perm value is in an acceptable
11895 range. */
11904 else
11909 }
11912 {
11917 }
11922 {
11927 }
11933 {
11937 }
11942 /* Some targets are deficient and fail to expand a single
11943 argument permutation while still allowing an equivalent
11944 2-argument version. */
11948 {
11951 }
11954 {
11961 }
11965 }
11971 }
11973 /* Perform constant folding and related simplification of EXPR.
11974 The related simplifications include x*1 => x, x*0 => 0, etc.,
11975 and application of the associative law.
11976 NOP_EXPR conversions may be removed freely (as long as we
11977 are careful not to change the type of the overall expression).
11978 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11979 but we can constant-fold them if they have constant operands. */
11981 #ifdef ENABLE_FOLD_CHECKING
11982 # define fold(x) fold_1 (x)
11984 static
11985 #endif
11986 tree
11988 {
11992 tree tem;
11995 /* Return right away if a constant. */
11999 /* CALL_EXPR-like objects with variable numbers of operands are
12000 treated specially. */
12002 {
12004 {
12007 }
12009 }
12012 {
12017 {
12035 }
12036 }
12039 {
12041 {
12048 {
12053 /* Find a matching index by means of a binary search. */
12055 {
12071 else
12073 }
12074 }
12077 }
12079 /* Return a VECTOR_CST if possible. */
12081 {
12088 tree value;
12091 {
12095 {
12098 }
12099 else
12101 }
12106 }
12114 }
12116 #ifdef ENABLE_FOLD_CHECKING
12117 #undef fold
12124 /* When --enable-checking=fold, compute a digest of expr before
12125 and after actual fold call to see if fold did not accidentally
12126 change original expr. */
12128 tree
12130 {
12131 tree ret;
12151 }
12153 void
12155 {
12166 }
12168 static void
12170 {
12172 }
12174 static void
12177 {
12183 recursive_label:
12193 {
12194 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12199 }
12206 {
12207 /* Allow these fields to be modified. */
12208 tree tmp;
12216 {
12219 }
12220 }
12231 {
12234 {
12249 }
12253 {
12266 }
12283 {
12289 }
12292 {
12294 {
12297 }
12299 }
12310 {
12313 }
12323 }
12324 }
12326 /* Helper function for outputting the checksum of a tree T. When
12327 debugging with gdb, you can "define mynext" to be "next" followed
12328 by "call debug_fold_checksum (op0)", then just trace down till the
12329 outputs differ. */
12331 DEBUG_FUNCTION void
12333 {
12348 }
12350 #endif
12352 /* Fold a unary tree expression with code CODE of type TYPE with an
12353 operand OP0. LOC is the location of the resulting expression.
12354 Return a folded expression if successful. Otherwise, return a tree
12355 expression with code CODE of type TYPE with an operand OP0. */
12357 tree
12360 {
12361 tree tem;
12362 #ifdef ENABLE_FOLD_CHECKING
12371 #endif
12377 #ifdef ENABLE_FOLD_CHECKING
12384 #endif
12386 }
12388 /* Fold a binary tree expression with code CODE of type TYPE with
12389 operands OP0 and OP1. LOC is the location of the resulting
12390 expression. Return a folded expression if successful. Otherwise,
12391 return a tree expression with code CODE of type TYPE with operands
12392 OP0 and OP1. */
12394 tree
12397 MEM_STAT_DECL)
12398 {
12399 tree tem;
12400 #ifdef ENABLE_FOLD_CHECKING
12417 #endif
12423 #ifdef ENABLE_FOLD_CHECKING
12438 #endif
12440 }
12442 /* Fold a ternary tree expression with code CODE of type TYPE with
12443 operands OP0, OP1, and OP2. Return a folded expression if
12444 successful. Otherwise, return a tree expression with code CODE of
12445 type TYPE with operands OP0, OP1, and OP2. */
12447 tree
12450 {
12451 tree tem;
12452 #ifdef ENABLE_FOLD_CHECKING
12476 #endif
12483 #ifdef ENABLE_FOLD_CHECKING
12506 #endif
12508 }
12510 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12511 arguments in ARGARRAY, and a null static chain.
12512 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12513 of type TYPE from the given operands as constructed by build_call_array. */
12515 tree
12518 {
12519 tree tem;
12520 #ifdef ENABLE_FOLD_CHECKING
12539 #endif
12545 #ifdef ENABLE_FOLD_CHECKING
12561 #endif
12563 }
12565 /* Perform constant folding and related simplification of initializer
12566 expression EXPR. These behave identically to "fold_buildN" but ignore
12567 potential run-time traps and exceptions that fold must preserve. */
12569 #define START_FOLD_INIT \
12570 int saved_signaling_nans = flag_signaling_nans;\
12571 int saved_trapping_math = flag_trapping_math;\
12572 int saved_rounding_math = flag_rounding_math;\
12573 int saved_trapv = flag_trapv;\
12574 int saved_folding_initializer = folding_initializer;\
12575 flag_signaling_nans = 0;\
12576 flag_trapping_math = 0;\
12577 flag_rounding_math = 0;\
12578 flag_trapv = 0;\
12579 folding_initializer = 1;
12581 #define END_FOLD_INIT \
12582 flag_signaling_nans = saved_signaling_nans;\
12583 flag_trapping_math = saved_trapping_math;\
12584 flag_rounding_math = saved_rounding_math;\
12585 flag_trapv = saved_trapv;\
12586 folding_initializer = saved_folding_initializer;
12588 tree
12591 {
12592 tree result;
12593 START_FOLD_INIT;
12597 END_FOLD_INIT;
12599 }
12601 tree
12604 {
12605 tree result;
12606 START_FOLD_INIT;
12610 END_FOLD_INIT;
12612 }
12614 tree
12617 {
12618 tree result;
12619 START_FOLD_INIT;
12623 END_FOLD_INIT;
12625 }
12627 #undef START_FOLD_INIT
12628 #undef END_FOLD_INIT
12630 /* Determine if first argument is a multiple of second argument. Return 0 if
12631 it is not, or we cannot easily determined it to be.
12633 An example of the sort of thing we care about (at this point; this routine
12634 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12635 fold cases do now) is discovering that
12637 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12639 is a multiple of
12641 SAVE_EXPR (J * 8)
12643 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12645 This code also handles discovering that
12647 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12649 is a multiple of 8 so we don't have to worry about dealing with a
12650 possible remainder.
12652 Note that we *look* inside a SAVE_EXPR only to determine how it was
12653 calculated; it is not safe for fold to do much of anything else with the
12654 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12655 at run time. For example, the latter example above *cannot* be implemented
12656 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12657 evaluation time of the original SAVE_EXPR is not necessarily the same at
12658 the time the new expression is evaluated. The only optimization of this
12659 sort that would be valid is changing
12661 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12663 divided by 8 to
12665 SAVE_EXPR (I) * SAVE_EXPR (J)
12667 (where the same SAVE_EXPR (J) is used in the original and the
12668 transformed version). */
12670 int
12672 {
12680 {
12682 /* Bitwise and provides a power of two multiple. If the mask is
12683 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12686 /* FALLTHRU */
12699 {
12703 /* const_binop may not detect overflow correctly,
12704 so check for it explicitly here. */
12708 size_one_node,
12709 op1)))
12712 }
12716 /* Can't handle conversions from non-integral or wider integral type. */
12722 /* .. fall through ... */
12739 SIGNED);
12743 }
12744 }
12746 /* Return true if CODE or TYPE is known to be non-negative. */
12748 static bool
12750 {
12753 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12754 have a signed:1 type (where the value is -1 and 0). */
12757 }
12759 /* Return true if (CODE OP0) is known to be non-negative. If the return
12760 value is based on the assumption that signed overflow is undefined,
12761 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12762 *STRICT_OVERFLOW_P. */
12764 bool
12767 {
12772 {
12774 /* We can't return 1 if flag_wrapv is set because
12775 ABS_EXPR<INT_MIN> = INT_MIN. */
12779 {
12782 }
12789 strict_overflow_p);
12791 CASE_CONVERT:
12792 {
12797 {
12800 strict_overflow_p);
12802 {
12806 strict_overflow_p);
12807 }
12808 }
12810 {
12813 strict_overflow_p);
12817 }
12818 }
12823 }
12825 /* We don't know sign of `t', so be conservative and return false. */
12827 }
12829 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12830 value is based on the assumption that signed overflow is undefined,
12831 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12832 *STRICT_OVERFLOW_P. */
12834 bool
12837 {
12842 {
12847 strict_overflow_p)
12849 strict_overflow_p));
12851 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12852 both unsigned and at least 2 bits shorter than the result. */
12856 {
12861 {
12865 }
12866 }
12871 {
12872 /* x * x is always non-negative for floating point x
12873 or without overflow. */
12877 {
12882 }
12883 }
12885 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12886 both unsigned and their total bits is shorter than the result. */
12890 {
12909 {
12919 }
12920 }
12926 strict_overflow_p)
12928 strict_overflow_p));
12939 strict_overflow_p)
12941 strict_overflow_p));
12948 strict_overflow_p);
12951 }
12953 /* We don't know sign of `t', so be conservative and return false. */
12955 }
12957 /* Return true if T is known to be non-negative. If the return
12958 value is based on the assumption that signed overflow is undefined,
12959 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12960 *STRICT_OVERFLOW_P. */
12962 bool
12964 {
12969 {
12981 strict_overflow_p)
12983 strict_overflow_p));
12987 }
12988 /* We don't know sign of `t', so be conservative and return false. */
12990 }
12992 /* Return true if T is known to be non-negative. If the return
12993 value is based on the assumption that signed overflow is undefined,
12994 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12995 *STRICT_OVERFLOW_P. */
12997 bool
13000 {
13003 {
13023 /* Always true. */
13027 /* sqrt(-0.0) is -0.0. */
13031 strict_overflow_p);
13068 /* True if the 1st argument is nonnegative. */
13070 strict_overflow_p);
13073 /* True if the 1st OR 2nd arguments are nonnegative. */
13075 strict_overflow_p)
13077 strict_overflow_p)));
13080 /* True if the 1st AND 2nd arguments are nonnegative. */
13082 strict_overflow_p)
13084 strict_overflow_p)));
13087 /* True if the 2nd argument is nonnegative. */
13089 strict_overflow_p);
13092 /* True if the 1st argument is nonnegative or the second
13093 argument is an even integer. */
13098 strict_overflow_p);
13101 /* True if the 1st argument is nonnegative or the second
13102 argument is an even integer valued real. */
13104 {
13105 REAL_VALUE_TYPE c;
13106 HOST_WIDE_INT n;
13111 {
13112 REAL_VALUE_TYPE cint;
13116 }
13117 }
13119 strict_overflow_p);
13123 }
13125 type);
13126 }
13128 /* Return true if T is known to be non-negative. If the return
13129 value is based on the assumption that signed overflow is undefined,
13130 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13131 *STRICT_OVERFLOW_P. */
13133 static bool
13135 {
13141 {
13143 {
13147 /* If the initializer is non-void, then it's a normal expression
13148 that will be assigned to the slot. */
13152 /* Otherwise, the initializer sets the slot in some way. One common
13153 way is an assignment statement at the end of the initializer. */
13155 {
13163 else
13165 }
13169 strict_overflow_p);
13172 }
13175 {
13181 arg0,
13182 arg1,
13183 strict_overflow_p);
13184 }
13188 strict_overflow_p);
13191 strict_overflow_p);
13194 strict_overflow_p);
13199 }
13201 /* We don't know sign of `t', so be conservative and return false. */
13203 }
13205 /* Return true if T is known to be non-negative. If the return
13206 value is based on the assumption that signed overflow is undefined,
13207 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13208 *STRICT_OVERFLOW_P. */
13210 bool
13212 {
13219 {
13226 strict_overflow_p);
13232 strict_overflow_p);
13241 }
13244 {
13252 strict_overflow_p);
13257 strict_overflow_p);
13270 }
13271 }
13273 /* Return true if `t' is known to be non-negative. Handle warnings
13274 about undefined signed overflow. */
13276 bool
13278 {
13285 "determining that expression is always "
13287 WARN_STRICT_OVERFLOW_MISC);
13289 }
13292 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13293 For floating point we further ensure that T is not denormal.
13294 Similar logic is present in nonzero_address in rtlanal.h.
13296 If the return value is based on the assumption that signed overflow
13297 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13298 change *STRICT_OVERFLOW_P. */
13300 bool
13303 {
13305 {
13308 strict_overflow_p);
13311 {
13317 strict_overflow_p));
13318 }
13323 strict_overflow_p);
13327 }
13330 }
13332 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13333 For floating point we further ensure that T is not denormal.
13334 Similar logic is present in nonzero_address in rtlanal.h.
13336 If the return value is based on the assumption that signed overflow
13337 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13338 change *STRICT_OVERFLOW_P. */
13340 bool
13342 tree type,
13343 tree op0,
13345 {
13348 {
13352 {
13353 /* With the presence of negative values it is hard
13354 to say something. */
13361 /* One of operands must be positive and the other non-negative. */
13362 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13363 overflows, on a twos-complement machine the sum of two
13364 nonnegative numbers can never be zero. */
13366 strict_overflow_p)
13368 strict_overflow_p));
13369 }
13374 {
13376 strict_overflow_p)
13378 strict_overflow_p))
13379 {
13382 }
13383 }
13392 {
13395 }
13402 {
13406 /* When both operands are nonzero, then MAX must be too. */
13408 strict_overflow_p))
13411 /* MAX where operand 0 is positive is positive. */
13413 strict_overflow_p);
13414 }
13415 /* MAX where operand 1 is positive is positive. */
13420 {
13424 }
13429 strict_overflow_p)
13431 strict_overflow_p));
13435 }
13438 }
13440 /* Return true when T is an address and is known to be nonzero.
13441 For floating point we further ensure that T is not denormal.
13442 Similar logic is present in nonzero_address in rtlanal.h.
13444 If the return value is based on the assumption that signed overflow
13445 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13446 change *STRICT_OVERFLOW_P. */
13448 bool
13450 {
13453 {
13458 {
13467 /* For objects in symbol table check if we know they are non-zero.
13468 Don't do anything for variables and functions before symtab is built;
13469 it is quite possible that they will be declared weak later. */
13471 {
13477 else
13479 }
13481 /* Function local objects are never NULL. */
13488 /* Constants are never weak. */
13493 }
13501 {
13505 }
13510 }
13512 }
13514 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13515 attempt to fold the expression to a constant without modifying TYPE,
13516 OP0 or OP1.
13518 If the expression could be simplified to a constant, then return
13519 the constant. If the expression would not be simplified to a
13520 constant, then return NULL_TREE. */
13522 tree
13524 {
13527 }
13529 /* Given the components of a unary expression CODE, TYPE and OP0,
13530 attempt to fold the expression to a constant without modifying
13531 TYPE or OP0.
13533 If the expression could be simplified to a constant, then return
13534 the constant. If the expression would not be simplified to a
13535 constant, then return NULL_TREE. */
13537 tree
13539 {
13542 }
13544 /* If EXP represents referencing an element in a constant string
13545 (either via pointer arithmetic or array indexing), return the
13546 tree representing the value accessed, otherwise return NULL. */
13548 tree
13550 {
13554 {
13556 tree index;
13557 tree string;
13562 else
13563 {
13567 /* Optimize the special-case of a zero lower bound.
13569 We convert the low_bound to sizetype to avoid some problems
13570 with constant folding. (E.g. suppose the lower bound is 1,
13571 and its mode is QI. Without the conversion,l (ARRAY
13572 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13573 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13579 }
13592 }
13594 }
13596 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13597 an integer constant, real, or fixed-point constant.
13599 TYPE is the type of the result. */
13601 static tree
13603 {
13607 {
13609 {
13616 }
13623 {
13624 FIXED_VALUE_TYPE f;
13629 /* Propagate overflow flags. */
13633 }
13637 }
13640 }
13642 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13643 an integer constant or real constant.
13645 TYPE is the type of the result. */
13647 tree
13649 {
13653 {
13655 {
13656 /* If the value is unsigned or non-negative, then the absolute value
13657 is the same as the ordinary value. */
13661 /* If the value is negative, then the absolute value is
13662 its negation. */
13663 else
13664 {
13669 }
13670 }
13676 else
13682 }
13685 }
13687 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13688 constant. TYPE is the type of the result. */
13690 static tree
13692 {
13696 }
13698 /* Given CODE, a relational operator, the target type, TYPE and two
13699 constant operands OP0 and OP1, return the result of the
13700 relational operation. If the result is not a compile time
13701 constant, then return NULL_TREE. */
13703 static tree
13705 {
13708 /* From here on, the only cases we handle are when the result is
13709 known to be a constant. */
13712 {
13716 /* Handle the cases where either operand is a NaN. */
13718 {
13720 {
13748 }
13751 }
13754 }
13757 {
13761 }
13763 /* Handle equality/inequality of complex constants. */
13765 {
13776 else
13778 }
13781 {
13788 {
13800 }
13803 }
13805 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13807 To compute GT, swap the arguments and do LT.
13808 To compute GE, do LT and invert the result.
13809 To compute LE, swap the arguments, do LT and invert the result.
13810 To compute NE, do EQ and invert the result.
13812 Therefore, the code below must handle only EQ and LT. */
13815 {
13818 }
13820 /* Note that it is safe to invert for real values here because we
13821 have already handled the one case that it matters. */
13825 {
13828 }
13830 /* Compute a result for LT or EQ if args permit;
13831 Otherwise return T. */
13833 {
13836 else
13838 }
13839 else
13845 }
13847 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13848 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13849 itself. */
13851 tree
13853 {
13854 /* If the expression does not have side effects then we don't have to wrap
13855 it with a cleanup point expression. */
13859 /* If the expression is a return, check to see if the expression inside the
13860 return has no side effects or the right hand side of the modify expression
13861 inside the return. If either don't have side effects set we don't need to
13862 wrap the expression in a cleanup point expression. Note we don't check the
13863 left hand side of the modify because it should always be a return decl. */
13865 {
13872 }
13875 }
13877 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13878 of an indirection through OP0, or NULL_TREE if no simplification is
13879 possible. */
13881 tree
13883 {
13885 tree subtype;
13893 {
13896 /* *&CONST_DECL -> to the value of the const decl. */
13899 /* *&p => p; make sure to handle *&"str"[cst] here. */
13901 {
13905 else
13907 }
13908 /* *(foo *)&fooarray => fooarray[0] */
13911 && (!in_gimple_form
13913 {
13923 }
13924 /* *(foo *)&complexfoo => __real__ complexfoo */
13928 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
13931 {
13935 }
13936 }
13940 {
13946 {
13947 tree op00type;
13951 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
13954 {
13966 }
13967 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13970 {
13974 }
13975 /* ((foo *)&fooarray)[1] => fooarray[1] */
13978 {
13988 }
13989 }
13990 }
13992 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
13995 && (!in_gimple_form
13997 {
13998 tree type_domain;
14008 NULL_TREE);
14009 }
14012 }
14014 /* Builds an expression for an indirection through T, simplifying some
14015 cases. */
14017 tree
14019 {
14027 }
14029 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14031 tree
14033 {
14038 else
14040 }
14042 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14043 whose result is ignored. The type of the returned tree need not be
14044 the same as the original expression. */
14046 tree
14048 {
14054 {
14065 else
14071 {
14087 }
14092 }
14093 }
14095 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14097 tree
14099 {
14105 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14106 have to do anything. Only do this when we are not given a const,
14107 because in that case, this check is more expensive than just
14108 doing it. */
14110 {
14115 }
14117 /* If divisor is a power of two, simplify this to bit manipulation. */
14119 {
14121 {
14135 }
14136 else
14137 {
14138 tree t;
14144 }
14145 }
14146 else
14147 {
14152 }
14155 }
14157 /* Likewise, but round down. */
14159 tree
14161 {
14168 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14169 have to do anything. Only do this when we are not given a const,
14170 because in that case, this check is more expensive than just
14171 doing it. */
14173 {
14178 }
14180 /* If divisor is a power of two, simplify this to bit manipulation. */
14182 {
14183 tree t;
14187 }
14188 else
14189 {
14194 }
14197 }
14199 /* Returns the pointer to the base of the object addressed by EXP and
14200 extracts the information about the offset of the access, storing it
14201 to PBITPOS and POFFSET. */
14203 static tree
14206 {
14207 tree core;
14208 machine_mode mode;
14210 HOST_WIDE_INT bitsize;
14214 {
14219 }
14220 else
14221 {
14225 }
14228 }
14230 /* Returns true if addresses of E1 and E2 differ by a constant, false
14231 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14233 bool
14235 {
14249 {
14259 }
14261 {
14262 /* If only one of the offsets is non-constant, the difference cannot
14263 be a constant. */
14265 }
14266 else
14271 }
14273 /* Simplify the floating point expression EXP when the sign of the
14274 result is not significant. Return NULL_TREE if no simplification
14275 is possible. */
14277 tree
14279 {
14284 {
14320 {
14323 {
14325 /* Strip copysign function call, return the 1st argument. */
14331 /* Strip sign ops from the argument of "odd" math functions. */
14333 {
14337 }
14339 }
14340 }
14345 }
14347 }
14349 /* Return OFF converted to a pointer offset type suitable as offset for
14350 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14351 tree
14353 {
14355 }
14357 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14358 tree
14360 {
14363 }
14365 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14366 tree
14368 {
14371 }