| blob | 16bff5f07be9f249e21325b08087f9e8141bdd57 |
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. */
78 #ifndef LOAD_EXTEND_OP
79 #define LOAD_EXTEND_OP(M) UNKNOWN
80 #endif
82 /* Nonzero if we are folding constants inside an initializer; zero
83 otherwise. */
86 /* The following constants represent a bit based encoding of GCC's
87 comparison operators. This encoding simplifies transformations
88 on relational comparison operators, such as AND and OR. */
106 };
122 HOST_WIDE_INT *,
151 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
152 Otherwise, return LOC. */
154 static location_t
156 {
159 }
161 /* Similar to protected_set_expr_location, but never modify x in place,
162 if location can and needs to be set, unshare it. */
166 {
172 {
175 }
177 }
178 \f
179 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
180 division and returns the quotient. Otherwise returns
181 NULL_TREE. */
183 tree
185 {
186 widest_int quo;
193 }
194 \f
195 /* This is nonzero if we should defer warnings about undefined
196 overflow. This facility exists because these warnings are a
197 special case. The code to estimate loop iterations does not want
198 to issue any warnings, since it works with expressions which do not
199 occur in user code. Various bits of cleanup code call fold(), but
200 only use the result if it has certain characteristics (e.g., is a
201 constant); that code only wants to issue a warning if the result is
202 used. */
206 /* If a warning about undefined overflow is deferred, this is the
207 warning. Note that this may cause us to turn two warnings into
208 one, but that is fine since it is sufficient to only give one
209 warning per expression. */
213 /* If a warning about undefined overflow is deferred, this is the
214 level at which the warning should be emitted. */
218 /* Start deferring overflow warnings. We could use a stack here to
219 permit nested calls, but at present it is not necessary. */
221 void
223 {
225 }
227 /* Stop deferring overflow warnings. If there is a pending warning,
228 and ISSUE is true, then issue the warning if appropriate. STMT is
229 the statement with which the warning should be associated (used for
230 location information); STMT may be NULL. CODE is the level of the
231 warning--a warn_strict_overflow_code value. This function will use
232 the smaller of CODE and the deferred code when deciding whether to
233 issue the warning. CODE may be zero to mean to always use the
234 deferred code. */
236 void
238 {
240 location_t locus;
245 {
251 }
262 /* Use the smallest code level when deciding to issue the
263 warning. */
272 else
275 }
277 /* Stop deferring overflow warnings, ignoring any deferred
278 warnings. */
280 void
282 {
284 }
286 /* Whether we are deferring overflow warnings. */
288 bool
290 {
292 }
294 /* This is called when we fold something based on the fact that signed
295 overflow is undefined. */
297 static void
299 {
301 {
304 {
307 }
308 }
311 }
312 \f
313 /* Return true if the built-in mathematical function specified by CODE
314 is odd, i.e. -f(x) == f(-x). */
316 bool
318 {
320 {
321 CASE_CFN_ASIN:
322 CASE_CFN_ASINH:
323 CASE_CFN_ATAN:
324 CASE_CFN_ATANH:
325 CASE_CFN_CASIN:
326 CASE_CFN_CASINH:
327 CASE_CFN_CATAN:
328 CASE_CFN_CATANH:
329 CASE_CFN_CBRT:
330 CASE_CFN_CPROJ:
331 CASE_CFN_CSIN:
332 CASE_CFN_CSINH:
333 CASE_CFN_CTAN:
334 CASE_CFN_CTANH:
335 CASE_CFN_ERF:
336 CASE_CFN_LLROUND:
337 CASE_CFN_LROUND:
338 CASE_CFN_ROUND:
339 CASE_CFN_SIN:
340 CASE_CFN_SINH:
341 CASE_CFN_TAN:
342 CASE_CFN_TANH:
343 CASE_CFN_TRUNC:
346 CASE_CFN_LLRINT:
347 CASE_CFN_LRINT:
348 CASE_CFN_NEARBYINT:
349 CASE_CFN_RINT:
354 }
356 }
358 /* Check whether we may negate an integer constant T without causing
359 overflow. */
361 bool
363 {
364 tree type;
373 }
375 /* Determine whether an expression T can be cheaply negated using
376 the function negate_expr without introducing undefined overflow. */
378 static bool
380 {
381 tree type;
390 {
395 /* Check that -CST will not overflow type. */
408 /* We want to canonicalize to positive real constants. Pretend
409 that only negative ones can be easily negated. */
417 {
428 }
443 /* -(A + B) -> (-B) - A. */
448 /* -(A + B) -> (-A) - B. */
452 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
463 /* INT_MIN/n * n doesn't overflow while negating one operand it does
464 if n is a power of two. */
473 /* Fall through. */
488 /* In general we can't negate B in A / B, because if A is INT_MIN and
489 B is 1, we may turn this into INT_MIN / -1 which is undefined
490 and actually traps on some architectures. */
499 /* Negate -((double)float) as (double)(-float). */
501 {
505 }
509 /* Negate -f(x) as f(-x). */
515 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
517 {
521 }
526 }
528 }
530 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
531 simplification is possible.
532 If negate_expr_p would return true for T, NULL_TREE will never be
533 returned. */
535 static tree
537 {
539 tree tem;
542 {
543 /* Convert - (~A) to A + 1. */
569 {
574 }
578 {
583 {
587 }
590 }
613 {
614 /* -(A + B) -> (-B) - A. */
618 {
622 }
624 /* -(A + B) -> (-A) - B. */
626 {
630 }
631 }
635 /* - (A - B) -> B - A */
647 /* Fall through. */
651 {
660 }
672 /* In general we can't negate B in A / B, because if A is INT_MIN and
673 B is 1, we may turn this into INT_MIN / -1 which is undefined
674 and actually traps on some architectures. */
686 /* Convert -((double)float) into (double)(-float). */
688 {
692 }
696 /* Negate -f(x) as f(-x). */
699 {
705 }
709 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
711 {
714 {
721 }
722 }
727 }
730 }
732 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
733 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
734 return NULL_TREE. */
736 static tree
738 {
740 location_t loc;
753 }
754 \f
755 /* Split a tree IN into a constant, literal and variable parts that could be
756 combined with CODE to make IN. "constant" means an expression with
757 TREE_CONSTANT but that isn't an actual constant. CODE must be a
758 commutative arithmetic operation. Store the constant part into *CONP,
759 the literal in *LITP and return the variable part. If a part isn't
760 present, set it to null. If the tree does not decompose in this way,
761 return the entire tree as the variable part and the other parts as null.
763 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
764 case, we negate an operand that was subtracted. Except if it is a
765 literal for which we use *MINUS_LITP instead.
767 If NEGATE_P is true, we are negating all of IN, again except a literal
768 for which we use *MINUS_LITP instead.
770 If IN is itself a literal or constant, return it as appropriate.
772 Note that we do not guarantee that any of the three values will be the
773 same type as IN, but they will have the same signedness and mode. */
775 static tree
778 {
785 /* Strip any conversions that don't change the machine mode or signedness. */
794 /* We can associate addition and subtraction together (even
795 though the C standard doesn't say so) for integers because
796 the value is not affected. For reals, the value might be
797 affected, so we can't. */
800 {
806 /* First see if either of the operands is a literal, then a constant. */
819 /* If we haven't dealt with either operand, this is not a case we can
820 decompose. Otherwise, VAR is either of the ones remaining, if any. */
825 else
828 /* Now do any needed negations. */
835 }
838 {
839 /* -X - 1 is folded to ~X, undo that here. */
842 }
845 else
849 {
856 }
859 }
861 /* Re-associate trees split by the above function. T1 and T2 are
862 either expressions to associate or null. Return the new
863 expression, if any. LOC is the location of the new expression. If
864 we build an operation, do it in TYPE and with CODE. */
866 static tree
868 {
874 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
875 try to fold this since we will have infinite recursion. But do
876 deal with any NEGATE_EXPRs. */
879 {
881 {
894 }
896 {
899 }
903 }
907 }
908 \f
909 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
910 for use in int_const_binop, size_binop and size_diffop. */
912 static bool
914 {
921 {
930 }
935 }
938 /* Combine two integer constants ARG1 and ARG2 under operation CODE
939 to produce a new constant. Return NULL_TREE if we don't know how
940 to evaluate CODE at compile-time. */
942 static tree
945 {
946 wide_int res;
947 tree t;
956 {
972 {
976 else
978 }
981 /* It's unclear from the C standard whether shifts can overflow.
982 The following code ignores overflow; perhaps a C standard
983 interpretation ruling is needed. */
985 else
992 {
996 else
998 }
1002 else
1081 }
1089 }
1091 tree
1093 {
1095 }
1097 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1098 constant. We assume ARG1 and ARG2 have the same data type, or at least
1099 are the same kind of constant and the same machine mode. Return zero if
1100 combining the constants is not allowed in the current operating mode. */
1102 static tree
1104 {
1105 /* Sanity check for the recursive cases. */
1113 {
1119 }
1122 {
1123 machine_mode mode;
1124 REAL_VALUE_TYPE d1;
1125 REAL_VALUE_TYPE d2;
1126 REAL_VALUE_TYPE value;
1127 REAL_VALUE_TYPE result;
1131 /* The following codes are handled by real_arithmetic. */
1133 {
1144 }
1152 /* Don't perform operation if we honor signaling NaNs and
1153 either operand is a NaN. */
1158 /* Don't perform operation if it would raise a division
1159 by zero exception. */
1165 /* If either operand is a NaN, just return it. Otherwise, set up
1166 for floating-point trap; we return an overflow. */
1175 /* Don't constant fold this floating point operation if
1176 the result has overflowed and flag_trapping_math. */
1184 /* Don't constant fold this floating point operation if the
1185 result may dependent upon the run-time rounding mode and
1186 flag_rounding_math is set, or if GCC's software emulation
1187 is unable to accurately represent the result. */
1197 }
1200 {
1201 FIXED_VALUE_TYPE f1;
1202 FIXED_VALUE_TYPE f2;
1203 FIXED_VALUE_TYPE result;
1208 /* The following codes are handled by fixed_arithmetic. */
1210 {
1222 {
1229 }
1234 }
1241 /* Propagate overflow flags. */
1245 }
1248 {
1257 {
1268 mpc_mul);
1282 mpc_div);
1283 /* Fallthru ... */
1289 {
1290 /* Keep this algorithm in sync with
1291 tree-complex.c:expand_complex_div_straight().
1293 Expand complex division to scalars, straightforward algorithm.
1294 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1295 t = br*br + bi*bi
1296 */
1297 tree magsquared
1301 tree t1
1305 tree t2
1312 }
1313 else
1314 {
1315 /* Keep this algorithm in sync with
1316 tree-complex.c:expand_complex_div_wide().
1318 Expand complex division to scalars, modified algorithm to minimize
1319 overflow with wide input ranges. */
1325 {
1326 /* In the TRUE branch, we compute
1327 ratio = br/bi;
1328 div = (br * ratio) + bi;
1329 tr = (ar * ratio) + ai;
1330 ti = (ai * ratio) - ar;
1331 tr = tr / div;
1332 ti = ti / div; */
1343 }
1344 else
1345 {
1346 /* In the FALSE branch, we compute
1347 ratio = d/c;
1348 divisor = (d * ratio) + c;
1349 tr = (b * ratio) + a;
1350 ti = b - (a * ratio);
1351 tr = tr / div;
1352 ti = ti / div; */
1364 }
1365 }
1370 }
1374 }
1378 {
1384 {
1390 /* It is possible that const_binop cannot handle the given
1391 code and return NULL_TREE */
1394 }
1397 }
1399 /* Shifts allow a scalar offset for a vector. */
1402 {
1408 {
1413 /* It is possible that const_binop cannot handle the given
1414 code and return NULL_TREE. */
1417 }
1420 }
1422 }
1424 /* Overload that adds a TYPE parameter to be able to dispatch
1425 to fold_relational_const. */
1427 tree
1429 {
1433 /* ??? Until we make the const_binop worker take the type of the
1434 result as argument put those cases that need it here. */
1436 {
1447 {
1463 {
1469 }
1472 }
1478 {
1503 {
1516 }
1519 }
1522 }
1527 /* Make sure type and arg0 have the same saturating flag. */
1532 }
1534 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1535 Return zero if computing the constants is not possible. */
1537 tree
1539 {
1541 {
1542 CASE_CONVERT:
1549 /* If the source address is 0, and the source address space
1550 cannot have a valid object at 0, fold to dest type null. */
1561 {
1562 /* Can't call fold_negate_const directly here as that doesn't
1563 handle all cases and we might not be able to negate some
1564 constants. */
1569 }
1578 {
1582 }
1588 /* Perform BIT_NOT_EXPR on each element individually. */
1590 {
1592 tree elem;
1597 {
1603 }
1606 }
1628 {
1647 else
1651 {
1655 }
1658 }
1663 {
1677 {
1682 }
1685 {
1689 }
1692 }
1696 }
1699 }
1701 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1702 indicates which particular sizetype to create. */
1704 tree
1706 {
1708 }
1709 \f
1710 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1711 is a tree code. The type of the result is taken from the operands.
1712 Both must be equivalent integer types, ala int_binop_types_match_p.
1713 If the operands are constant, so is the result. */
1715 tree
1717 {
1726 /* Handle the special case of two integer constants faster. */
1728 {
1729 /* And some specific cases even faster than that. */
1731 {
1736 }
1738 {
1741 }
1743 {
1746 }
1748 /* Handle general case of two integer constants. For sizetype
1749 constant calculations we always want to know about overflow,
1750 even in the unsigned case. */
1752 }
1755 }
1757 /* Given two values, either both of sizetype or both of bitsizetype,
1758 compute the difference between the two values. Return the value
1759 in signed type corresponding to the type of the operands. */
1761 tree
1763 {
1765 tree ctype;
1770 /* If the type is already signed, just do the simple thing. */
1778 else
1781 /* If either operand is not a constant, do the conversions to the signed
1782 type and subtract. The hardware will do the right thing with any
1783 overflow in the subtraction. */
1789 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1790 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1791 overflow) and negate (which can't either). Special-case a result
1792 of zero while we're here. */
1798 else
1802 MINUS_EXPR,
1804 }
1805 \f
1806 /* A subroutine of fold_convert_const handling conversions of an
1807 INTEGER_CST to another integer type. */
1809 static tree
1811 {
1812 /* Given an integer constant, make new constant with new type,
1813 appropriately sign-extended or truncated. Use widest_int
1814 so that any extension is done according ARG1's type. */
1818 }
1820 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1821 to an integer type. */
1823 static tree
1825 {
1827 tree t;
1829 /* The following code implements the floating point to integer
1830 conversion rules required by the Java Language Specification,
1831 that IEEE NaNs are mapped to zero and values that overflow
1832 the target precision saturate, i.e. values greater than
1833 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1834 are mapped to INT_MIN. These semantics are allowed by the
1835 C and C++ standards that simply state that the behavior of
1836 FP-to-integer conversion is unspecified upon overflow. */
1838 wide_int val;
1839 REAL_VALUE_TYPE r;
1843 {
1850 }
1852 /* If R is NaN, return zero and show we have an overflow. */
1854 {
1857 }
1859 /* See if R is less than the lower bound or greater than the
1860 upper bound. */
1863 {
1867 {
1870 }
1871 }
1874 {
1877 {
1880 {
1883 }
1884 }
1885 }
1892 }
1894 /* A subroutine of fold_convert_const handling conversions of a
1895 FIXED_CST to an integer type. */
1897 static tree
1899 {
1900 tree t;
1904 /* Right shift FIXED_CST to temp by fbit. */
1908 {
1910 HOST_BITS_PER_DOUBLE_INT,
1913 /* Left shift temp to temp_trunc by fbit. */
1915 HOST_BITS_PER_DOUBLE_INT,
1917 }
1918 else
1919 {
1922 }
1924 /* If FIXED_CST is negative, we need to round the value toward 0.
1925 By checking if the fractional bits are not zero to add 1 to temp. */
1931 /* Given a fixed-point constant, make new constant with new type,
1932 appropriately sign-extended or truncated. */
1940 }
1942 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1943 to another floating point type. */
1945 static tree
1947 {
1948 REAL_VALUE_TYPE value;
1949 tree t;
1954 /* If converting an infinity or NAN to a representation that doesn't
1955 have one, set the overflow bit so that we can produce some kind of
1956 error message at the appropriate point if necessary. It's not the
1957 most user-friendly message, but it's better than nothing. */
1964 /* Regular overflow, conversion produced an infinity in a mode that
1965 can't represent them. */
1970 else
1973 }
1975 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1976 to a floating point type. */
1978 static tree
1980 {
1981 REAL_VALUE_TYPE value;
1982 tree t;
1989 }
1991 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1992 to another fixed-point type. */
1994 static tree
1996 {
1997 FIXED_VALUE_TYPE value;
1998 tree t;
2005 /* Propagate overflow flags. */
2009 }
2011 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2012 to a fixed-point type. */
2014 static tree
2016 {
2017 FIXED_VALUE_TYPE value;
2018 tree t;
2020 double_int di;
2027 else
2035 /* Propagate overflow flags. */
2039 }
2041 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2042 to a fixed-point type. */
2044 static tree
2046 {
2047 FIXED_VALUE_TYPE value;
2048 tree t;
2056 /* Propagate overflow flags. */
2060 }
2062 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2063 type TYPE. If no simplification can be done return NULL_TREE. */
2065 static tree
2067 {
2073 {
2080 }
2082 {
2089 }
2091 {
2098 }
2100 {
2103 {
2108 {
2114 }
2116 }
2117 }
2119 }
2121 /* Construct a vector of zero elements of vector type TYPE. */
2123 static tree
2125 {
2126 tree t;
2130 }
2132 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2134 bool
2136 {
2151 {
2170 }
2171 }
2173 /* Convert expression ARG to type TYPE. Used by the middle-end for
2174 simple conversions in preference to calling the front-end's convert. */
2176 tree
2178 {
2180 tree tem;
2191 {
2194 /* Handle conversions between pointers to different address spaces. */
2199 /* fall through */
2204 {
2208 }
2222 {
2226 }
2228 {
2232 }
2234 {
2238 }
2241 {
2259 }
2264 {
2268 }
2271 {
2285 }
2289 {
2298 integer_zero_node));
2300 {
2304 {
2310 }
2318 }
2322 }
2340 }
2341 fold_convert_exit:
2344 }
2345 \f
2346 /* Return false if expr can be assumed not to be an lvalue, true
2347 otherwise. */
2349 static bool
2351 {
2352 /* We only need to wrap lvalue tree codes. */
2354 {
2385 /* Assume the worst for front-end tree codes. */
2389 }
2392 }
2394 /* Return an expr equal to X but certainly not valid as an lvalue. */
2396 tree
2398 {
2399 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2400 us. */
2407 }
2409 /* When pedantic, return an expr equal to X but certainly not valid as a
2410 pedantic lvalue. Otherwise, return X. */
2412 static tree
2414 {
2416 }
2417 \f
2418 /* Given a tree comparison code, return the code that is the logical inverse.
2419 It is generally not safe to do this for floating-point comparisons, except
2420 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2421 ERROR_MARK in this case. */
2423 enum tree_code
2425 {
2431 {
2462 }
2463 }
2465 /* Similar, but return the comparison that results if the operands are
2466 swapped. This is safe for floating-point. */
2468 enum tree_code
2470 {
2472 {
2498 }
2499 }
2502 /* Convert a comparison tree code from an enum tree_code representation
2503 into a compcode bit-based encoding. This function is the inverse of
2504 compcode_to_comparison. */
2506 static enum comparison_code
2508 {
2510 {
2541 }
2542 }
2544 /* Convert a compcode bit-based encoding of a comparison operator back
2545 to GCC's enum tree_code representation. This function is the
2546 inverse of comparison_to_compcode. */
2548 static enum tree_code
2550 {
2552 {
2583 }
2584 }
2586 /* Return a tree for the comparison which is the combination of
2587 doing the AND or OR (depending on CODE) of the two operations LCODE
2588 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2589 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2590 if this makes the transformation invalid. */
2592 tree
2597 {
2604 {
2615 }
2618 {
2619 /* Eliminate unordered comparisons, as well as LTGT and ORD
2620 which are not used unless the mode has NaNs. */
2626 }
2628 {
2629 /* Check that the original operation and the optimized ones will trap
2630 under the same condition. */
2641 /* In a short-circuited boolean expression the LHS might be
2642 such that the RHS, if evaluated, will never trap. For
2643 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2644 if neither x nor y is NaN. (This is a mixed blessing: for
2645 example, the expression above will never trap, hence
2646 optimizing it to x < y would be invalid). */
2651 /* If the comparison was short-circuited, and only the RHS
2652 trapped, we may now generate a spurious trap. */
2657 /* If we changed the conditions that cause a trap, we lose. */
2660 }
2666 else
2667 {
2672 }
2673 }
2674 \f
2675 /* Return nonzero if two operands (typically of the same tree node)
2676 are necessarily equal. FLAGS modifies behavior as follows:
2678 If OEP_ONLY_CONST is set, only return nonzero for constants.
2679 This function tests whether the operands are indistinguishable;
2680 it does not test whether they are equal using C's == operation.
2681 The distinction is important for IEEE floating point, because
2682 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2683 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2685 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2686 even though it may hold multiple values during a function.
2687 This is because a GCC tree node guarantees that nothing else is
2688 executed between the evaluation of its "operands" (which may often
2689 be evaluated in arbitrary order). Hence if the operands themselves
2690 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2691 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2692 unset means assuming isochronic (or instantaneous) tree equivalence.
2693 Unless comparing arbitrary expression trees, such as from different
2694 statements, this flag can usually be left unset.
2696 If OEP_PURE_SAME is set, then pure functions with identical arguments
2697 are considered the same. It is used when the caller has other ways
2698 to ensure that global memory is unchanged in between.
2700 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2701 not values of expressions.
2703 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2704 any operand with side effect. This is unnecesarily conservative in the
2705 case we know that arg0 and arg1 are in disjoint code paths (such as in
2706 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2707 addresses with TREE_CONSTANT flag set so we know that &var == &var
2708 even if var is volatile. */
2710 int
2712 {
2713 /* If either is ERROR_MARK, they aren't equal. */
2719 /* Similar, if either does not have a type (like a released SSA name),
2720 they aren't equal. */
2724 /* We cannot consider pointers to different address space equal. */
2731 /* Check equality of integer constants before bailing out due to
2732 precision differences. */
2734 {
2735 /* Address of INTEGER_CST is not defined; check that we did not forget
2736 to drop the OEP_ADDRESS_OF flags. */
2739 }
2742 {
2743 /* If both types don't have the same signedness, then we can't consider
2744 them equal. We must check this before the STRIP_NOPS calls
2745 because they may change the signedness of the arguments. As pointers
2746 strictly don't have a signedness, require either two pointers or
2747 two non-pointers as well. */
2753 /* If both types don't have the same precision, then it is not safe
2754 to strip NOPs. */
2761 }
2762 #if 0
2763 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2764 sanity check once the issue is solved. */
2765 else
2766 /* Addresses of conversions and SSA_NAMEs (and many other things)
2767 are not defined. Check that we did not forget to drop the
2768 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2771 #endif
2773 /* In case both args are comparisons but with different comparison
2774 code, try to swap the comparison operands of one arg to produce
2775 a match and compare that variant. */
2779 {
2787 }
2790 {
2791 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2793 ;
2795 {
2796 /* If we are interested in comparing addresses ignore
2797 MEM_REF wrappings of the base that can appear just for
2798 TBAA reasons. */
2812 }
2813 else
2815 }
2817 /* When not checking adddresses, this is needed for conversions and for
2818 COMPONENT_REF. Might as well play it safe and always test this. */
2825 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2826 We don't care about side effects in that case because the SAVE_EXPR
2827 takes care of that for us. In all other cases, two expressions are
2828 equal if they have no side effects. If we have two identical
2829 expressions with side effects that should be treated the same due
2830 to the only side effects being identical SAVE_EXPR's, that will
2831 be detected in the recursive calls below.
2832 If we are taking an invariant address of two identical objects
2833 they are necessarily equal as well. */
2840 /* Next handle constant cases, those for which we can return 1 even
2841 if ONLY_CONST is set. */
2844 {
2858 {
2859 /* If we do not distinguish between signed and unsigned zero,
2860 consider them equal. */
2863 }
2867 {
2874 {
2878 }
2880 }
2884 flags)
2886 flags));
2897 flags | OEP_ADDRESS_OF
2900 /* In GIMPLE empty constructors are allowed in initializers of
2901 aggregates. */
2906 }
2911 /* Define macros to test an operand from arg0 and arg1 for equality and a
2912 variant that allows null and views null as being different from any
2913 non-null value. In the latter case, if either is null, the both
2914 must be; otherwise, do the normal comparison. */
2915 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2916 TREE_OPERAND (arg1, N), flags)
2918 #define OP_SAME_WITH_NULL(N) \
2919 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2920 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2923 {
2925 /* Two conversions are equal only if signedness and modes match. */
2927 {
2928 CASE_CONVERT:
2936 }
2946 /* For commutative ops, allow the other order. */
2954 /* If either of the pointer (or reference) expressions we are
2955 dereferencing contain a side effect, these cannot be equal,
2956 but their addresses can be. */
2963 {
2980 {
2981 /* Require equal access sizes */
2987 flags)))
2989 /* Verify that accesses are TBAA compatible. */
2991 && (!alias_ptr_types_compatible_p
2999 /* Verify that alignment is compatible. */
3003 }
3006 /* TARGET_MEM_REF require equal extra operands. */
3014 /* Operands 2 and 3 may be null.
3015 Compare the array index by value if it is constant first as we
3016 may have different types but same value here. */
3027 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3028 may be NULL when we're called to compare MEM_EXPRs. */
3043 }
3047 {
3049 /* Be sure we pass right ADDRESS_OF flag. */
3067 /* The multiplcation operands are commutative. */
3068 /* FALLTHRU */
3076 /* Otherwise take into account this is a commutative operation. */
3089 }
3093 {
3097 /* If not both CALL_EXPRs are either internal or normal function
3098 functions, then they are not equal. */
3101 {
3102 /* If the CALL_EXPRs call different internal functions, then they
3103 are not equal. */
3106 }
3107 else
3108 {
3109 /* If the CALL_EXPRs call different functions, then they are not
3110 equal. */
3112 flags))
3114 }
3116 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3117 {
3121 else
3125 }
3127 /* Now see if all the arguments are the same. */
3128 {
3139 /* If we get here and both argument lists are exhausted
3140 then the CALL_EXPRs are equal. */
3142 }
3145 }
3148 /* Consider __builtin_sqrt equal to sqrt. */
3156 {
3157 /* In GIMPLE constructors are used only to build vectors from
3158 elements. Individual elements in the constructor must be
3159 indexed in increasing order and form an initial sequence.
3161 We make no effort to compare constructors in generic.
3162 (see sem_variable::equals in ipa-icf which can do so for
3163 constants). */
3168 /* Be sure that vectors constructed have the same representation.
3169 We only tested element precision and modes to match.
3170 Vectors may be BLKmode and thus also check that the number of
3171 parts match. */
3184 {
3189 /* In GIMPLE the indexes can be either NULL or matching i.
3190 Double check this so we won't get false
3191 positives for GENERIC. */
3199 }
3201 }
3206 }
3208 #undef OP_SAME
3209 #undef OP_SAME_WITH_NULL
3210 }
3211 \f
3212 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3213 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3215 When in doubt, return 0. */
3217 static int
3219 {
3231 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3232 and see if the inner values are the same. This removes any
3233 signedness comparison, which doesn't matter here. */
3240 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3241 actual comparison operand, ARG0.
3243 First throw away any conversions to wider types
3244 already present in the operands. */
3253 {
3256 /* Make sure shorter operand is extended the right way
3257 to match the longer operand. */
3263 }
3266 }
3267 \f
3268 /* See if ARG is an expression that is either a comparison or is performing
3269 arithmetic on comparisons. The comparisons must only be comparing
3270 two different values, which will be stored in *CVAL1 and *CVAL2; if
3271 they are nonzero it means that some operands have already been found.
3272 No variables may be used anywhere else in the expression except in the
3273 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3274 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3276 If this is true, return 1. Otherwise, return zero. */
3278 static int
3280 {
3284 /* We can handle some of the tcc_expression cases here. */
3294 {
3295 /* If we've already found a CVAL1 or CVAL2, this expression is
3296 two complex to handle. */
3302 }
3305 {
3328 /* First see if we can handle the first operand, then the second. For
3329 the second operand, we know *CVAL1 can't be zero. It must be that
3330 one side of the comparison is each of the values; test for the
3331 case where this isn't true by failing if the two operands
3332 are the same. */
3341 ;
3345 ;
3346 else
3350 ;
3354 ;
3355 else
3362 }
3363 }
3364 \f
3365 /* ARG is a tree that is known to contain just arithmetic operations and
3366 comparisons. Evaluate the operations in the tree substituting NEW0 for
3367 any occurrence of OLD0 as an operand of a comparison and likewise for
3368 NEW1 and OLD1. */
3370 static tree
3373 {
3378 /* We can handle some of the tcc_expression cases here. */
3386 {
3401 {
3420 }
3421 /* Fall through - ??? */
3424 {
3428 /* We need to check both for exact equality and tree equality. The
3429 former will be true if the operand has a side-effect. In that
3430 case, we know the operand occurred exactly once. */
3443 }
3447 }
3448 }
3449 \f
3450 /* Return a tree for the case when the result of an expression is RESULT
3451 converted to TYPE and OMITTED was previously an operand of the expression
3452 but is now not needed (e.g., we folded OMITTED * 0).
3454 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3455 the conversion of RESULT to TYPE. */
3457 tree
3459 {
3462 /* If the resulting operand is an empty statement, just return the omitted
3463 statement casted to void. */
3473 }
3475 /* Return a tree for the case when the result of an expression is RESULT
3476 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3477 of the expression but are now not needed.
3479 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3480 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3481 evaluated before OMITTED2. Otherwise, if neither has side effects,
3482 just do the conversion of RESULT to TYPE. */
3484 tree
3487 {
3496 }
3498 \f
3499 /* Return a simplified tree node for the truth-negation of ARG. This
3500 never alters ARG itself. We assume that ARG is an operation that
3501 returns a truth value (0 or 1).
3503 FIXME: one would think we would fold the result, but it causes
3504 problems with the dominator optimizer. */
3506 static tree
3508 {
3513 /* If this is a comparison, we can simply invert it, except for
3514 floating-point non-equality comparisons, in which case we just
3515 enclose a TRUTH_NOT_EXPR around what we have. */
3518 {
3521 && flag_trapping_math
3532 }
3535 {
3554 /* Here we can invert either operand. We invert the first operand
3555 unless the second operand is a TRUTH_NOT_EXPR in which case our
3556 result is the XOR of the first operand with the inside of the
3557 negation of the second operand. */
3562 else
3585 {
3592 /* A COND_EXPR may have a throw as one operand, which
3593 then has void type. Just leave void operands
3594 as they are. */
3600 }
3612 CASE_CONVERT:
3616 /* ... fall through ... */
3638 }
3639 }
3641 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3642 assume that ARG is an operation that returns a truth value (0 or 1
3643 for scalars, 0 or -1 for vectors). Return the folded expression if
3644 folding is successful. Otherwise, return NULL_TREE. */
3646 static tree
3648 {
3651 ? BIT_NOT_EXPR
3654 }
3656 /* Return a simplified tree node for the truth-negation of ARG. This
3657 never alters ARG itself. We assume that ARG is an operation that
3658 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3660 tree
3662 {
3668 ? BIT_NOT_EXPR
3671 }
3673 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3674 with code CODE. This optimization is unsafe. */
3675 static tree
3678 {
3682 /* (A / C) +- (B / C) -> (A +- B) / C. */
3692 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3697 {
3709 }
3712 }
3713 \f
3714 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3715 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3716 and uses reverse storage order if REVERSEP is nonzero. */
3718 static tree
3722 {
3726 {
3733 }
3748 }
3750 /* Optimize a bit-field compare.
3752 There are two cases: First is a compare against a constant and the
3753 second is a comparison of two items where the fields are at the same
3754 bit position relative to the start of a chunk (byte, halfword, word)
3755 large enough to contain it. In these cases we can avoid the shift
3756 implicit in bitfield extractions.
3758 For constants, we emit a compare of the shifted constant with the
3759 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3760 compared. For two fields at the same position, we do the ANDs with the
3761 similar mask and compare the result of the ANDs.
3763 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3764 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3765 are the left and right operands of the comparison, respectively.
3767 If the optimization described above can be done, we return the resulting
3768 tree. Otherwise we return zero. */
3770 static tree
3773 {
3776 tree unsigned_type;
3783 tree mask;
3784 tree offset;
3786 /* Get all the information about the extractions being done. If the bit size
3787 if the same as the size of the underlying object, we aren't doing an
3788 extraction at all and so can do nothing. We also don't want to
3789 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3790 then will no longer be able to replace it. */
3799 else
3800 {
3801 /* If this is not a constant, we can only do something if bit positions,
3802 sizes, signedness and storage order are the same. */
3803 rinner
3811 }
3813 /* See if we can find a mode to refer to this field. We should be able to,
3814 but fail if we can't. */
3823 /* Set signed and unsigned types of the precision of this mode for the
3824 shifts below. */
3827 /* Compute the bit position and size for the new reference and our offset
3828 within it. If the new reference is the same size as the original, we
3829 won't optimize anything, so return zero. */
3839 /* Make the mask to be used against the extracted field. */
3846 /* If not comparing with constant, just rework the comparison
3847 and return. */
3851 unsigned_type,
3854 mask),
3857 unsigned_type,
3860 mask));
3862 /* Otherwise, we are handling the constant case. See if the constant is too
3863 big for the field. Warn and return a tree for 0 (false) if so. We do
3864 this not only for its own sake, but to avoid having to test for this
3865 error case below. If we didn't, we might generate wrong code.
3867 For unsigned fields, the constant shifted right by the field length should
3868 be all zero. For signed fields, the high-order bits should agree with
3869 the sign bit. */
3872 {
3874 {
3878 }
3879 }
3880 else
3881 {
3884 {
3888 }
3889 }
3891 /* Single-bit compares should always be against zero. */
3893 {
3896 }
3898 /* Make a new bitfield reference, shift the constant over the
3899 appropriate number of bits and mask it with the computed mask
3900 (in case this was a signed field). If we changed it, make a new one. */
3902 lreversep);
3908 mask);
3913 }
3914 \f
3915 /* Subroutine for fold_truth_andor_1: decode a field reference.
3917 If EXP is a comparison reference, we return the innermost reference.
3919 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3920 set to the starting bit number.
3922 If the innermost field can be completely contained in a mode-sized
3923 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3925 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3926 otherwise it is not changed.
3928 *PUNSIGNEDP is set to the signedness of the field.
3930 *PREVERSEP is set to the storage order of the field.
3932 *PMASK is set to the mask used. This is either contained in a
3933 BIT_AND_EXPR or derived from the width of the field.
3935 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3937 Return 0 if this is not a component reference or is one that we can't
3938 do anything with. */
3940 static tree
3945 {
3949 tree unsigned_type;
3952 /* All the optimizations using this function assume integer fields.
3953 There are problems with FP fields since the type_for_size call
3954 below can fail for, e.g., XFmode. */
3958 /* We are interested in the bare arrangement of bits, so strip everything
3959 that doesn't affect the machine mode. However, record the type of the
3960 outermost expression if it may matter below. */
3967 {
3973 }
3982 /* If the number of bits in the reference is the same as the bitsize of
3983 the outer type, then the outer type gives the signedness. Otherwise
3984 (in case of a small bitfield) the signedness is unchanged. */
3988 /* Compute the mask to access the bitfield. */
3997 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4005 }
4007 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4008 bit positions and MASK is SIGNED. */
4010 static int
4012 {
4016 /* If this function returns true when the type of the mask is
4017 UNSIGNED, then there will be errors. In particular see
4018 gcc.c-torture/execute/990326-1.c. There does not appear to be
4019 any documentation paper trail as to why this is so. But the pre
4020 wide-int worked with that restriction and it has been preserved
4021 here. */
4026 }
4028 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4029 represents the sign bit of EXP's type. If EXP represents a sign
4030 or zero extension, also test VAL against the unextended type.
4031 The return value is the (sub)expression whose sign bit is VAL,
4032 or NULL_TREE otherwise. */
4034 tree
4036 {
4038 tree t;
4040 /* Tree EXP must have an integral type. */
4045 /* Tree VAL must be an integer constant. */
4054 /* Handle extension from a narrower type. */
4060 }
4062 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4063 to be evaluated unconditionally. */
4065 static int
4067 {
4068 /* Strip any conversions that don't change the machine mode. */
4077 /* Don't regard global variables as simple. They may be
4078 allocated in ways unknown to the compiler (shared memory,
4079 #pragma weak, etc). */
4082 /* Weakrefs are not safe to be read, since they can be NULL.
4083 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4084 have DECL_WEAK flag set. */
4086 /* Loading a static variable is unduly expensive, but global
4087 registers aren't expensive. */
4089 }
4091 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4092 to be evaluated unconditionally.
4093 I addition to simple_operand_p, we assume that comparisons, conversions,
4094 and logic-not operations are simple, if their operands are simple, too. */
4096 static bool
4098 {
4118 }
4120 \f
4121 /* The following functions are subroutines to fold_range_test and allow it to
4122 try to change a logical combination of comparisons into a range test.
4124 For example, both
4125 X == 2 || X == 3 || X == 4 || X == 5
4126 and
4127 X >= 2 && X <= 5
4128 are converted to
4129 (unsigned) (X - 2) <= 3
4131 We describe each set of comparisons as being either inside or outside
4132 a range, using a variable named like IN_P, and then describe the
4133 range with a lower and upper bound. If one of the bounds is omitted,
4134 it represents either the highest or lowest value of the type.
4136 In the comments below, we represent a range by two numbers in brackets
4137 preceded by a "+" to designate being inside that range, or a "-" to
4138 designate being outside that range, so the condition can be inverted by
4139 flipping the prefix. An omitted bound is represented by a "-". For
4140 example, "- [-, 10]" means being outside the range starting at the lowest
4141 possible value and ending at 10, in other words, being greater than 10.
4142 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4143 always false.
4145 We set up things so that the missing bounds are handled in a consistent
4146 manner so neither a missing bound nor "true" and "false" need to be
4147 handled using a special case. */
4149 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4150 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4151 and UPPER1_P are nonzero if the respective argument is an upper bound
4152 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4153 must be specified for a comparison. ARG1 will be converted to ARG0's
4154 type if both are specified. */
4156 static tree
4159 {
4160 tree tem;
4164 /* If neither arg represents infinity, do the normal operation.
4165 Else, if not a comparison, return infinity. Else handle the special
4166 comparison rules. Note that most of the cases below won't occur, but
4167 are handled for consistency. */
4170 {
4175 }
4180 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4181 for neither. In real maths, we cannot assume open ended ranges are
4182 the same. But, this is computer arithmetic, where numbers are finite.
4183 We can therefore make the transformation of any unbounded range with
4184 the value Z, Z being greater than any representable number. This permits
4185 us to treat unbounded ranges as equal. */
4189 {
4210 }
4213 }
4214 \f
4215 /* Helper routine for make_range. Perform one step for it, return
4216 new expression if the loop should continue or NULL_TREE if it should
4217 stop. */
4219 tree
4223 {
4229 {
4231 /* We can only do something if the range is testing for zero. */
4240 /* We can only do something if the range is testing for zero
4241 and if the second operand is an integer constant. Note that
4242 saying something is "in" the range we make is done by
4243 complementing IN_P since it will set in the initial case of
4244 being not equal to zero; "out" is leaving it alone. */
4251 {
4272 }
4274 /* If this is an unsigned comparison, we also know that EXP is
4275 greater than or equal to zero. We base the range tests we make
4276 on that fact, so we record it here so we can parse existing
4277 range tests. We test arg0_type since often the return type
4278 of, e.g. EQ_EXPR, is boolean. */
4280 {
4284 NULL_TREE))
4289 /* If the high bound is missing, but we have a nonzero low
4290 bound, reverse the range so it goes from zero to the low bound
4291 minus 1. */
4293 {
4298 }
4299 }
4307 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4308 low and high are non-NULL, then normalize will DTRT. */
4311 {
4316 }
4318 /* (-x) IN [a,b] -> x in [-b, -a] */
4330 /* ~ X -> -X - 1 */
4339 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4340 move a constant to the other side. */
4345 /* If EXP is signed, any overflow in the computation is undefined,
4346 so we don't worry about it so long as our computations on
4347 the bounds don't overflow. For unsigned, overflow is defined
4348 and this is exactly the right thing. */
4360 normalize:
4361 /* Check for an unsigned range which has wrapped around the maximum
4362 value thus making n_high < n_low, and normalize it. */
4364 {
4370 /* If the range is of the form +/- [ x+1, x ], we won't
4371 be able to normalize it. But then, it represents the
4372 whole range or the empty set, so make it
4373 +/- [ -, - ]. */
4377 else
4379 }
4380 else
4388 CASE_CONVERT:
4406 /* If we're converting arg0 from an unsigned type, to exp,
4407 a signed type, we will be doing the comparison as unsigned.
4408 The tests above have already verified that LOW and HIGH
4409 are both positive.
4411 So we have to ensure that we will handle large unsigned
4412 values the same way that the current signed bounds treat
4413 negative values. */
4416 {
4417 tree high_positive;
4418 tree equiv_type;
4419 /* For fixed-point modes, we need to pass the saturating flag
4420 as the 2nd parameter. */
4422 equiv_type
4425 else
4426 equiv_type
4429 /* A range without an upper bound is, naturally, unbounded.
4430 Since convert would have cropped a very large value, use
4431 the max value for the destination type. */
4432 high_positive
4439 high_positive),
4442 /* If the low bound is specified, "and" the range with the
4443 range for which the original unsigned value will be
4444 positive. */
4446 {
4449 integer_zero_node),
4450 high_positive))
4454 }
4455 else
4456 {
4457 /* Otherwise, "or" the range with the range of the input
4458 that will be interpreted as negative. */
4461 integer_zero_node),
4462 high_positive))
4466 }
4467 }
4476 }
4477 }
4479 /* Given EXP, a logical expression, set the range it is testing into
4480 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4481 actually being tested. *PLOW and *PHIGH will be made of the same
4482 type as the returned expression. If EXP is not a comparison, we
4483 will most likely not be returning a useful value and range. Set
4484 *STRICT_OVERFLOW_P to true if the return value is only valid
4485 because signed overflow is undefined; otherwise, do not change
4486 *STRICT_OVERFLOW_P. */
4488 tree
4491 {
4499 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4500 and see if we can refine the range. Some of the cases below may not
4501 happen, but it doesn't seem worth worrying about this. We "continue"
4502 the outer loop when we've changed something; otherwise we "break"
4503 the switch, which will "break" the while. */
4509 {
4515 {
4523 }
4532 }
4534 /* If EXP is a constant, we can evaluate whether this is true or false. */
4536 {
4543 }
4547 }
4548 \f
4549 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4550 type, TYPE, return an expression to test if EXP is in (or out of, depending
4551 on IN_P) the range. Return 0 if the test couldn't be created. */
4553 tree
4556 {
4559 /* Disable this optimization for function pointer expressions
4560 on targets that require function pointer canonicalization. */
4567 {
4573 }
4591 {
4593 {
4597 }
4599 }
4601 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4603 {
4607 {
4609 {
4612 etype
4614 else
4617 }
4620 }
4621 }
4623 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4624 This requires wrap-around arithmetics for the type of the expression.
4625 First make sure that arithmetics in this type is valid, then make sure
4626 that it wraps around. */
4632 {
4635 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4636 for the type in question, as we rely on this here. */
4646 else
4648 }
4658 {
4660 {
4665 }
4667 }
4675 }
4676 \f
4677 /* Return the predecessor of VAL in its type, handling the infinite case. */
4679 static tree
4681 {
4687 else
4690 }
4692 /* Return the successor of VAL in its type, handling the infinite case. */
4694 static tree
4696 {
4702 else
4705 }
4707 /* Given two ranges, see if we can merge them into one. Return 1 if we
4708 can, 0 if we can't. Set the output range into the specified parameters. */
4710 bool
4713 {
4717 tree tem;
4727 /* Make range 0 be the range that starts first, or ends last if they
4728 start at the same value. Swap them if it isn't. */
4731 || (lowequal
4734 {
4738 }
4740 /* Now flag two cases, whether the ranges are disjoint or whether the
4741 second range is totally subsumed in the first. Note that the tests
4742 below are simplified by the ones above. */
4748 /* We now have four cases, depending on whether we are including or
4749 excluding the two ranges. */
4751 {
4752 /* If they don't overlap, the result is false. If the second range
4753 is a subset it is the result. Otherwise, the range is from the start
4754 of the second to the end of the first. */
4759 else
4761 }
4764 {
4765 /* If they don't overlap, the result is the first range. If they are
4766 equal, the result is false. If the second range is a subset of the
4767 first, and the ranges begin at the same place, we go from just after
4768 the end of the second range to the end of the first. If the second
4769 range is not a subset of the first, or if it is a subset and both
4770 ranges end at the same place, the range starts at the start of the
4771 first range and ends just before the second range.
4772 Otherwise, we can't describe this as a single range. */
4778 {
4783 {
4784 /* We are in the weird situation where high0 > high1 but
4785 high1 has no successor. Punt. */
4787 }
4788 }
4790 {
4795 {
4796 /* low0 < low1 but low1 has no predecessor. Punt. */
4798 }
4799 }
4800 else
4802 }
4805 {
4806 /* If they don't overlap, the result is the second range. If the second
4807 is a subset of the first, the result is false. Otherwise,
4808 the range starts just after the first range and ends at the
4809 end of the second. */
4814 else
4815 {
4820 {
4821 /* high1 > high0 but high0 has no successor. Punt. */
4823 }
4824 }
4825 }
4827 else
4828 {
4829 /* The case where we are excluding both ranges. Here the complex case
4830 is if they don't overlap. In that case, the only time we have a
4831 range is if they are adjacent. If the second is a subset of the
4832 first, the result is the first. Otherwise, the range to exclude
4833 starts at the beginning of the first range and ends at the end of the
4834 second. */
4836 {
4841 else
4842 {
4843 /* Canonicalize - [min, x] into - [-, x]. */
4846 {
4851 /* FALLTHROUGH */
4864 }
4866 /* Canonicalize - [x, max] into - [x, -]. */
4869 {
4874 /* FALLTHROUGH */
4890 }
4892 /* The ranges might be also adjacent between the maximum and
4893 minimum values of the given type. For
4894 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4895 return + [x + 1, y - 1]. */
4897 {
4904 }
4905 else
4907 }
4908 }
4911 else
4913 }
4917 }
4918 \f
4920 /* Subroutine of fold, looking inside expressions of the form
4921 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4922 of the COND_EXPR. This function is being used also to optimize
4923 A op B ? C : A, by reversing the comparison first.
4925 Return a folded expression whose code is not a COND_EXPR
4926 anymore, or NULL_TREE if no folding opportunity is found. */
4928 static tree
4931 {
4936 tree tem;
4941 /* If we have A op 0 ? A : -A, consider applying the following
4942 transformations:
4944 A == 0? A : -A same as -A
4945 A != 0? A : -A same as A
4946 A >= 0? A : -A same as abs (A)
4947 A > 0? A : -A same as abs (A)
4948 A <= 0? A : -A same as -abs (A)
4949 A < 0? A : -A same as -abs (A)
4951 None of these transformations work for modes with signed
4952 zeros. If A is +/-0, the first two transformations will
4953 change the sign of the result (from +0 to -0, or vice
4954 versa). The last four will fix the sign of the result,
4955 even though the original expressions could be positive or
4956 negative, depending on the sign of A.
4958 Note that all these transformations are correct if A is
4959 NaN, since the two alternatives (A and -A) are also NaNs. */
4966 /* In the case that A is of the form X-Y, '-A' (arg2) may
4967 have already been folded to Y-X, check for that. */
4975 {
4989 /* Fall through. */
5009 }
5011 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5012 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5013 both transformations are correct when A is NaN: A != 0
5014 is then true, and A == 0 is false. */
5018 {
5023 }
5025 /* Try some transformations of A op B ? A : B.
5027 A == B? A : B same as B
5028 A != B? A : B same as A
5029 A >= B? A : B same as max (A, B)
5030 A > B? A : B same as max (B, A)
5031 A <= B? A : B same as min (A, B)
5032 A < B? A : B same as min (B, A)
5034 As above, these transformations don't work in the presence
5035 of signed zeros. For example, if A and B are zeros of
5036 opposite sign, the first two transformations will change
5037 the sign of the result. In the last four, the original
5038 expressions give different results for (A=+0, B=-0) and
5039 (A=-0, B=+0), but the transformed expressions do not.
5041 The first two transformations are correct if either A or B
5042 is a NaN. In the first transformation, the condition will
5043 be false, and B will indeed be chosen. In the case of the
5044 second transformation, the condition A != B will be true,
5045 and A will be chosen.
5047 The conversions to max() and min() are not correct if B is
5048 a number and A is not. The conditions in the original
5049 expressions will be false, so all four give B. The min()
5050 and max() versions would give a NaN instead. */
5053 /* Avoid these transformations if the COND_EXPR may be used
5054 as an lvalue in the C++ front-end. PR c++/19199. */
5055 && (in_gimple_form
5061 {
5066 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5068 {
5072 }
5075 {
5084 /* In C++ a ?: expression can be an lvalue, so put the
5085 operand which will be used if they are equal first
5086 so that we can convert this back to the
5087 corresponding COND_EXPR. */
5089 {
5098 }
5105 {
5114 }
5129 }
5130 }
5132 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5133 we might still be able to simplify this. For example,
5134 if C1 is one less or one more than C2, this might have started
5135 out as a MIN or MAX and been transformed by this function.
5136 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5142 {
5146 /* We can replace A with C1 in this case. */
5151 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5152 MIN_EXPR, to preserve the signedness of the comparison. */
5154 OEP_ONLY_CONST)
5158 OEP_ONLY_CONST))
5159 {
5162 arg2));
5165 }
5169 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5170 as above. */
5172 OEP_ONLY_CONST)
5176 OEP_ONLY_CONST))
5177 {
5180 arg2));
5183 }
5187 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5188 MAX_EXPR, to preserve the signedness of the comparison. */
5190 OEP_ONLY_CONST)
5194 OEP_ONLY_CONST))
5195 {
5198 arg2));
5200 }
5204 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5206 OEP_ONLY_CONST)
5210 OEP_ONLY_CONST))
5211 {
5214 arg2));
5216 }
5222 }
5225 }
5228 \f
5229 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5230 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5231 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5232 false) >= 2)
5233 #endif
5235 /* EXP is some logical combination of boolean tests. See if we can
5236 merge it into some range test. Return the new tree if so. */
5238 static tree
5241 {
5257 /* If this is an OR operation, invert both sides; we will invert
5258 again at the end. */
5262 /* If both expressions are the same, if we can merge the ranges, and we
5263 can build the range test, return it or it inverted. If one of the
5264 ranges is always true or always false, consider it to be the same
5265 expression as the other. */
5273 {
5277 }
5279 /* On machines where the branch cost is expensive, if this is a
5280 short-circuited branch and the underlying object on both sides
5281 is the same, make a non-short-circuit operation. */
5287 {
5288 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5289 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5290 which cases we can't do this. */
5298 {
5307 {
5310 WARN_STRICT_OVERFLOW_COMPARISON);
5314 }
5315 }
5316 }
5319 }
5320 \f
5321 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5322 bit value. Arrange things so the extra bits will be set to zero if and
5323 only if C is signed-extended to its full width. If MASK is nonzero,
5324 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5326 static tree
5328 {
5331 tree temp;
5336 /* We work by getting just the sign bit into the low-order bit, then
5337 into the high-order bit, then sign-extend. We then XOR that value
5338 with C. */
5341 /* We must use a signed type in order to get an arithmetic right shift.
5342 However, we must also avoid introducing accidental overflows, so that
5343 a subsequent call to integer_zerop will work. Hence we must
5344 do the type conversion here. At this point, the constant is either
5345 zero or one, and the conversion to a signed type can never overflow.
5346 We could get an overflow if this conversion is done anywhere else. */
5355 /* If necessary, convert the type back to match the type of C. */
5360 }
5361 \f
5362 /* For an expression that has the form
5363 (A && B) || ~B
5364 or
5365 (A || B) && ~B,
5366 we can drop one of the inner expressions and simplify to
5367 A || ~B
5368 or
5369 A && ~B
5370 LOC is the location of the resulting expression. OP is the inner
5371 logical operation; the left-hand side in the examples above, while CMPOP
5372 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5373 removing a condition that guards another, as in
5374 (A != NULL && A->...) || A == NULL
5375 which we must not transform. If RHS_ONLY is true, only eliminate the
5376 right-most operand of the inner logical operation. */
5378 static tree
5381 {
5399 {
5402 {
5405 }
5406 }
5408 {
5411 {
5414 }
5415 }
5430 }
5432 /* Find ways of folding logical expressions of LHS and RHS:
5433 Try to merge two comparisons to the same innermost item.
5434 Look for range tests like "ch >= '0' && ch <= '9'".
5435 Look for combinations of simple terms on machines with expensive branches
5436 and evaluate the RHS unconditionally.
5438 For example, if we have p->a == 2 && p->b == 4 and we can make an
5439 object large enough to span both A and B, we can do this with a comparison
5440 against the object ANDed with the a mask.
5442 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5443 operations to do this with one comparison.
5445 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5446 function and the one above.
5448 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5449 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5451 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5452 two operands.
5454 We return the simplified tree or 0 if no optimization is possible. */
5456 static tree
5459 {
5460 /* If this is the "or" of two comparisons, we can do something if
5461 the comparisons are NE_EXPR. If this is the "and", we can do something
5462 if the comparisons are EQ_EXPR. I.e.,
5463 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5465 WANTED_CODE is this operation code. For single bit fields, we can
5466 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5467 comparison for one-bit fields. */
5488 /* Start by getting the comparison codes. Fail if anything is volatile.
5489 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5490 it were surrounded with a NE_EXPR. */
5499 {
5503 }
5506 {
5510 }
5521 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5524 {
5527 {
5532 }
5535 {
5541 }
5542 }
5547 /* If the RHS can be evaluated unconditionally and its operands are
5548 simple, it wins to evaluate the RHS unconditionally on machines
5549 with expensive branches. In this case, this isn't a comparison
5550 that can be merged. */
5557 {
5558 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5569 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5579 }
5581 /* See if the comparisons can be merged. Then get all the parameters for
5582 each side. */
5607 /* It must be true that the inner operation on the lhs of each
5608 comparison must be the same if we are to be able to do anything.
5609 Then see if we have constants. If not, the same must be true for
5610 the rhs's. */
5619 {
5622 }
5627 else
5630 /* If either comparison code is not correct for our logical operation,
5631 fail. However, we can convert a one-bit comparison against zero into
5632 the opposite comparison against that bit being set in the field. */
5636 {
5638 {
5639 /* Make the left operand unsigned, since we are only interested
5640 in the value of one bit. Otherwise we are doing the wrong
5641 thing below. */
5644 }
5645 else
5647 }
5649 /* This is analogous to the code for l_const above. */
5651 {
5653 {
5656 }
5657 else
5659 }
5661 /* See if we can find a mode that contains both fields being compared on
5662 the left. If we can't, fail. Otherwise, update all constants and masks
5663 to be relative to a field of that size. */
5668 volatilep);
5678 {
5681 }
5689 {
5696 {
5700 }
5701 }
5703 {
5710 {
5714 }
5715 }
5717 /* If the right sides are not constant, do the same for it. Also,
5718 disallow this optimization if a size or signedness mismatch occurs
5719 between the left and right sides. */
5721 {
5724 /* Make sure the two fields on the right
5725 correspond to the left without being swapped. */
5733 volatilep);
5743 {
5746 }
5755 /* Make a mask that corresponds to both fields being compared.
5756 Do this for both items being compared. If the operands are the
5757 same size and the bits being compared are in the same position
5758 then we can do this by masking both and comparing the masked
5759 results. */
5763 {
5775 }
5777 /* There is still another way we can do something: If both pairs of
5778 fields being compared are adjacent, we may be able to make a wider
5779 field containing them both.
5781 Note that we still must mask the lhs/rhs expressions. Furthermore,
5782 the mask must be shifted to account for the shift done by
5783 make_bit_field_ref. */
5788 {
5789 tree type;
5805 /* Convert to the smaller type before masking out unwanted bits. */
5808 {
5810 {
5814 }
5816 {
5820 }
5821 }
5830 }
5833 }
5835 /* Handle the case of comparisons with constants. If there is something in
5836 common between the masks, those bits of the constants must be the same.
5837 If not, the condition is always false. Test for this to avoid generating
5838 incorrect code below. */
5843 {
5845 {
5848 }
5849 else
5850 {
5853 }
5854 }
5856 /* Construct the expression we will return. First get the component
5857 reference we will make. Unless the mask is all ones the width of
5858 that field, perform the mask operation. Then compare with the
5859 merged constant. */
5869 }
5870 \f
5871 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5872 constant. */
5874 static tree
5877 {
5880 tree comp_const;
5881 tree minmax_const;
5883 tree inner;
5894 /* If something does not permit us to optimize, return the original tree. */
5902 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5903 and GT_EXPR, doing the rest with recursive calls using logical
5904 simplifications. */
5906 {
5908 {
5909 tree tem
5916 }
5919 return
5921 optimize_minmax_comparison
5923 optimize_minmax_comparison
5928 /* MAX (X, 0) == 0 -> X <= 0 */
5932 /* MAX (X, 0) == 5 -> X == 5 */
5936 /* MAX (X, 0) == -1 -> false */
5940 /* MIN (X, 0) == 0 -> X >= 0 */
5944 /* MIN (X, 0) == 5 -> false */
5947 else
5948 /* MIN (X, 0) == -1 -> X == -1 */
5953 /* MAX (X, 0) > 0 -> X > 0
5954 MAX (X, 0) > 5 -> X > 5 */
5958 /* MAX (X, 0) > -1 -> true */
5962 /* MIN (X, 0) > 0 -> false
5963 MIN (X, 0) > 5 -> false */
5966 else
5967 /* MIN (X, 0) > -1 -> X > -1 */
5972 }
5973 }
5974 \f
5975 /* T is an integer expression that is being multiplied, divided, or taken a
5976 modulus (CODE says which and what kind of divide or modulus) by a
5977 constant C. See if we can eliminate that operation by folding it with
5978 other operations already in T. WIDE_TYPE, if non-null, is a type that
5979 should be used for the computation if wider than our type.
5981 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5982 (X * 2) + (Y * 4). We must, however, be assured that either the original
5983 expression would not overflow or that overflow is undefined for the type
5984 in the language in question.
5986 If we return a non-null expression, it is an equivalent form of the
5987 original computation, but need not be in the original type.
5989 We set *STRICT_OVERFLOW_P to true if the return values depends on
5990 signed overflow being undefined. Otherwise we do not change
5991 *STRICT_OVERFLOW_P. */
5993 static tree
5996 {
5997 /* To avoid exponential search depth, refuse to allow recursion past
5998 three levels. Beyond that (1) it's highly unlikely that we'll find
5999 something interesting and (2) we've probably processed it before
6000 when we built the inner expression. */
6003 tree ret;
6008 depth++;
6010 depth--;
6013 }
6015 static tree
6018 {
6029 /* Don't deal with constants of zero here; they confuse the code below. */
6039 /* Note that we need not handle conditional operations here since fold
6040 already handles those cases. So just do arithmetic here. */
6042 {
6044 /* For a constant, we can always simplify if we are a multiply
6045 or (for divide and modulus) if it is a multiple of our constant. */
6048 {
6051 /* If the multiplication overflowed to INT_MIN then we lost sign
6052 information on it and a subsequent multiplication might
6053 spuriously overflow. See PR68142. */
6058 }
6062 /* If op0 is an expression ... */
6068 /* ... and has wrapping overflow, and its type is smaller
6069 than ctype, then we cannot pass through as widening. */
6074 /* ... or this is a truncation (t is narrower than op0),
6075 then we cannot pass through this narrowing. */
6078 /* ... or signedness changes for division or modulus,
6079 then we cannot pass through this conversion. */
6083 /* ... or has undefined overflow while the converted to
6084 type has not, we cannot do the operation in the inner type
6085 as that would introduce undefined overflow. */
6091 /* Pass the constant down and see if we can make a simplification. If
6092 we can, replace this expression with the inner simplification for
6093 possible later conversion to our or some other type. */
6098 code == MULT_EXPR
6100 strict_overflow_p))))
6105 /* If widening the type changes it from signed to unsigned, then we
6106 must avoid building ABS_EXPR itself as unsigned. */
6108 {
6112 {
6115 }
6117 }
6118 /* If the constant is negative, we cannot simplify this. */
6121 /* FALLTHROUGH */
6123 /* For division and modulus, type can't be unsigned, as e.g.
6124 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6125 For signed types, even with wrapping overflow, this is fine. */
6134 /* If widening the type changes the signedness, then we can't perform
6135 this optimization as that changes the result. */
6139 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6145 {
6152 }
6156 /* If the second operand is constant, this is a multiplication
6157 or floor division, by a power of two, so we can treat it that
6158 way unless the multiplier or divisor overflows. Signed
6159 left-shift overflow is implementation-defined rather than
6160 undefined in C90, so do not convert signed left shift into
6161 multiplication. */
6164 /* const_binop may not detect overflow correctly,
6165 so check for it explicitly here. */
6169 size_one_node,
6170 op1)))
6174 ctype,
6176 t1),
6181 /* See if we can eliminate the operation on both sides. If we can, we
6182 can return a new PLUS or MINUS. If we can't, the only remaining
6183 cases where we can do anything are if the second operand is a
6184 constant. */
6190 /* If not multiplication, we can only do this if both operands
6191 are divisible by c. */
6194 {
6199 }
6201 /* If this was a subtraction, negate OP1 and set it to be an addition.
6202 This simplifies the logic below. */
6204 {
6206 /* If OP1 was not easily negatable, the constant may be OP0. */
6208 {
6211 }
6212 }
6217 /* If either OP1 or C are negative, this optimization is not safe for
6218 some of the division and remainder types while for others we need
6219 to change the code. */
6221 {
6229 }
6231 /* If it's a multiply or a division/modulus operation of a multiple
6232 of our constant, do the operation and verify it doesn't overflow. */
6235 {
6238 /* We allow the constant to overflow with wrapping semantics. */
6242 }
6243 else
6246 /* If we have an unsigned type, we cannot widen the operation since it
6247 will change the result if the original computation overflowed. */
6251 /* If we were able to eliminate our operation from the first side,
6252 apply our operation to the second side and reform the PLUS. */
6256 /* The last case is if we are a multiply. In that case, we can
6257 apply the distributive law to commute the multiply and addition
6258 if the multiplication of the constants doesn't overflow
6259 and overflow is defined. With undefined overflow
6260 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6266 op1);
6271 /* We have a special case here if we are doing something like
6272 (C * 8) % 4 since we know that's zero. */
6275 /* If the multiplication can overflow we cannot optimize this. */
6279 {
6282 }
6284 /* ... fall through ... */
6288 /* If we can extract our operation from the LHS, do so and return a
6289 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6290 do something only if the second operand is a constant. */
6304 /* If these are the same operation types, we can associate them
6305 assuming no overflow. */
6307 {
6317 {
6322 }
6323 }
6325 /* If these operations "cancel" each other, we have the main
6326 optimizations of this pass, which occur when either constant is a
6327 multiple of the other, in which case we replace this with either an
6328 operation or CODE or TCODE.
6330 If we have an unsigned type, we cannot do this since it will change
6331 the result if the original computation overflowed. */
6338 {
6340 {
6347 }
6349 {
6356 }
6357 }
6362 }
6365 }
6366 \f
6367 /* Return a node which has the indicated constant VALUE (either 0 or
6368 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6369 and is of the indicated TYPE. */
6371 tree
6373 {
6382 else
6384 }
6387 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6388 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6389 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6390 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6391 COND is the first argument to CODE; otherwise (as in the example
6392 given here), it is the second argument. TYPE is the type of the
6393 original expression. Return NULL_TREE if no simplification is
6394 possible. */
6396 static tree
6401 {
6411 {
6415 /* If this operand throws an expression, then it does not make
6416 sense to try to perform a logical or arithmetic operation
6417 involving it. */
6422 }
6423 else
6424 {
6429 }
6434 /* This transformation is only worthwhile if we don't have to wrap ARG
6435 in a SAVE_EXPR and the operation can be simplified without recursing
6436 on at least one of the branches once its pushed inside the COND_EXPR. */
6445 {
6449 else
6451 }
6453 {
6457 else
6459 }
6461 /* Check that we have simplified at least one of the branches. */
6466 }
6468 \f
6469 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6471 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6472 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6473 ADDEND is the same as X.
6475 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6476 and finite. The problematic cases are when X is zero, and its mode
6477 has signed zeros. In the case of rounding towards -infinity,
6478 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6479 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6481 bool
6483 {
6487 /* Don't allow the fold with -fsignaling-nans. */
6491 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6495 /* In a vector or complex, we would need to check the sign of all zeros. */
6499 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6503 /* The mode has signed zeros, and we have to honor their sign.
6504 In this situation, there is only one case we can return true for.
6505 X - 0 is the same as X unless rounding towards -infinity is
6506 supported. */
6508 }
6510 /* Subroutine of fold() that optimizes comparisons of a division by
6511 a nonzero integer constant against an integer constant, i.e.
6512 X/C1 op C2.
6514 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6515 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6516 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6518 The function returns the constant folded tree if a simplification
6519 can be made, and NULL_TREE otherwise. */
6521 static tree
6524 {
6532 /* We have to do this the hard way to detect unsigned overflow.
6533 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6539 {
6544 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6548 }
6550 {
6554 {
6573 }
6574 }
6575 else
6576 {
6577 /* A negative divisor reverses the relational operators. */
6583 {
6602 }
6603 }
6606 {
6627 {
6630 }
6635 {
6638 }
6643 {
6646 }
6651 {
6654 }
6659 }
6662 }
6665 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6666 equality/inequality test, then return a simplified form of the test
6667 using a sign testing. Otherwise return NULL. TYPE is the desired
6668 result type. */
6670 static tree
6673 tree result_type)
6674 {
6675 /* If this is testing a single bit, we can optimize the test. */
6679 {
6680 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6681 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6685 /* This is only a win if casting to a signed type is cheap,
6686 i.e. when arg00's type is not a partial mode. */
6689 {
6692 result_type,
6695 }
6696 }
6699 }
6701 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6702 equality/inequality test, then return a simplified form of
6703 the test using shifts and logical operations. Otherwise return
6704 NULL. TYPE is the desired result type. */
6706 tree
6709 {
6710 /* If this is testing a single bit, we can optimize the test. */
6714 {
6723 /* First, see if we can fold the single bit test into a sign-bit
6724 test. */
6726 result_type);
6730 /* Otherwise we have (A & C) != 0 where C is a single bit,
6731 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6732 Similarly for (A & C) == 0. */
6734 /* If INNER is a right shift of a constant and it plus BITNUM does
6735 not overflow, adjust BITNUM and INNER. */
6741 {
6744 }
6746 /* If we are going to be able to omit the AND below, we must do our
6747 operations as unsigned. If we must use the AND, we have a choice.
6748 Normally unsigned is faster, but for some machines signed is. */
6766 /* Put the AND last so it can combine with more things. */
6769 /* Make sure to return the proper type. */
6773 }
6775 }
6777 /* Check whether we are allowed to reorder operands arg0 and arg1,
6778 such that the evaluation of arg1 occurs before arg0. */
6780 static bool
6782 {
6789 }
6791 /* Test whether it is preferable two swap two operands, ARG0 and
6792 ARG1, for example because ARG0 is an integer constant and ARG1
6793 isn't. If REORDER is true, only recommend swapping if we can
6794 evaluate the operands in reverse order. */
6796 bool
6798 {
6816 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6817 for commutative and comparison operators. Ensuring a canonical
6818 form allows the optimizers to find additional redundancies without
6819 having to explicitly check for both orderings. */
6825 /* Put SSA_NAMEs last. */
6831 /* Put variables last. */
6838 }
6841 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6842 means A >= Y && A != MAX, but in this case we know that
6843 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6845 static tree
6847 {
6854 else
6863 {
6866 }
6868 {
6871 }
6872 else
6879 {
6880 /* Convert the pointer types into integer before taking the difference. */
6884 }
6885 else
6892 }
6894 /* Fold a sum or difference of at least one multiplication.
6895 Returns the folded tree or NULL if no simplification could be made. */
6897 static tree
6900 {
6904 /* (A * C) +- (B * C) -> (A+-B) * C.
6905 (A * C) +- A -> A * (C+-1).
6906 We are most concerned about the case where C is a constant,
6907 but other combinations show up during loop reduction. Since
6908 it is not difficult, try all four possibilities. */
6911 {
6914 }
6916 {
6919 }
6920 else
6921 {
6922 /* We cannot generate constant 1 for fract. */
6927 }
6929 {
6932 }
6934 {
6936 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6937 the purpose of this canonicalization. */
6941 {
6944 }
6945 else
6947 }
6948 else
6949 {
6950 /* We cannot generate constant 1 for fract. */
6955 }
6967 /* No identical multiplicands; see if we can find a common
6968 power-of-two factor in non-power-of-two multiplies. This
6969 can help in multi-dimensional array access. */
6972 {
6975 tree maybe_same;
6979 /* Move min of absolute values to int11. */
6981 {
6986 }
6987 else
6991 /* The remainder should not be a constant, otherwise we
6992 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6993 increased the number of multiplications necessary. */
6995 {
7003 }
7004 }
7014 }
7016 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7017 specified by EXPR into the buffer PTR of length LEN bytes.
7018 Return the number of bytes placed in the buffer, or zero
7019 upon failure. */
7021 static int
7023 {
7037 {
7039 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7040 number of bytes. */
7044 {
7051 else
7053 }
7054 else
7059 }
7061 }
7064 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7065 specified by EXPR into the buffer PTR of length LEN bytes.
7066 Return the number of bytes placed in the buffer, or zero
7067 upon failure. */
7069 static int
7071 {
7075 FIXED_VALUE_TYPE value;
7091 }
7094 /* Subroutine of native_encode_expr. Encode the REAL_CST
7095 specified by EXPR into the buffer PTR of length LEN bytes.
7096 Return the number of bytes placed in the buffer, or zero
7097 upon failure. */
7099 static int
7101 {
7107 /* There are always 32 bits in each long, no matter the size of
7108 the hosts long. We handle floating point representations with
7109 up to 192 bits. */
7123 {
7128 {
7135 else
7137 }
7138 else
7144 }
7146 }
7148 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7149 specified by EXPR into the buffer PTR of length LEN bytes.
7150 Return the number of bytes placed in the buffer, or zero
7151 upon failure. */
7153 static int
7155 {
7157 tree part;
7172 }
7175 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7176 specified by EXPR into the buffer PTR of length LEN bytes.
7177 Return the number of bytes placed in the buffer, or zero
7178 upon failure. */
7180 static int
7182 {
7192 {
7194 {
7197 }
7208 }
7210 }
7213 /* Subroutine of native_encode_expr. Encode the STRING_CST
7214 specified by EXPR into the buffer PTR of length LEN bytes.
7215 Return the number of bytes placed in the buffer, or zero
7216 upon failure. */
7218 static int
7220 {
7222 HOST_WIDE_INT total_bytes;
7236 {
7239 {
7242 }
7245 }
7246 else
7249 }
7252 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7253 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7254 buffer PTR of length LEN bytes. If OFF is not -1 then start
7255 the encoding at byte offset OFF and encode at most LEN bytes.
7256 Return the number of bytes placed in the buffer, or zero upon failure. */
7258 int
7260 {
7261 /* We don't support starting at negative offset and -1 is special. */
7266 {
7287 }
7288 }
7291 /* Subroutine of native_interpret_expr. Interpret the contents of
7292 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7293 If the buffer cannot be interpreted, return NULL_TREE. */
7295 static tree
7297 {
7307 }
7310 /* Subroutine of native_interpret_expr. Interpret the contents of
7311 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7312 If the buffer cannot be interpreted, return NULL_TREE. */
7314 static tree
7316 {
7318 double_int result;
7319 FIXED_VALUE_TYPE fixed_value;
7329 }
7332 /* Subroutine of native_interpret_expr. Interpret the contents of
7333 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7334 If the buffer cannot be interpreted, return NULL_TREE. */
7336 static tree
7338 {
7342 /* There are always 32 bits in each long, no matter the size of
7343 the hosts long. We handle floating point representations with
7344 up to 192 bits. */
7345 REAL_VALUE_TYPE r;
7356 {
7357 /* Both OFFSET and BYTE index within a long;
7358 bitpos indexes the whole float. */
7361 {
7368 else
7370 }
7371 else
7372 {
7375 {
7376 /* Reverse bytes within each long, or within the entire float
7377 if it's smaller than a long (for HFmode). */
7380 }
7381 }
7385 }
7389 }
7392 /* Subroutine of native_interpret_expr. Interpret the contents of
7393 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7394 If the buffer cannot be interpreted, return NULL_TREE. */
7396 static tree
7398 {
7413 }
7416 /* Subroutine of native_interpret_expr. Interpret the contents of
7417 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7418 If the buffer cannot be interpreted, return NULL_TREE. */
7420 static tree
7422 {
7435 {
7440 }
7442 }
7445 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7446 the buffer PTR of length LEN as a constant of type TYPE. For
7447 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7448 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7449 return NULL_TREE. */
7451 tree
7453 {
7455 {
7477 }
7478 }
7480 /* Returns true if we can interpret the contents of a native encoding
7481 as TYPE. */
7483 static bool
7485 {
7487 {
7500 }
7501 }
7503 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7504 TYPE at compile-time. If we're unable to perform the conversion
7505 return NULL_TREE. */
7507 static tree
7509 {
7510 /* We support up to 512-bit values (for V8DFmode). */
7514 /* Check that the host and target are sane. */
7523 }
7525 /* Build an expression for the address of T. Folds away INDIRECT_REF
7526 to avoid confusing the gimplify process. */
7528 tree
7530 {
7531 /* The size of the object is not relevant when talking about its address. */
7536 {
7541 }
7551 {
7556 }
7557 else
7561 }
7563 /* Build an expression for the address of T. */
7565 tree
7567 {
7571 }
7573 /* Fold a unary expression of code CODE and type TYPE with operand
7574 OP0. Return the folded expression if folding is successful.
7575 Otherwise, return NULL_TREE. */
7577 tree
7579 {
7580 tree tem;
7581 tree arg0;
7589 {
7592 {
7593 /* Don't use STRIP_NOPS, because signedness of argument type
7594 matters. */
7596 }
7597 else
7598 {
7599 /* Strip any conversions that don't change the mode. This
7600 is safe for every expression, except for a comparison
7601 expression because its signedness is derived from its
7602 operands.
7604 Note that this is done as an internal manipulation within
7605 the constant folder, in order to find the simplest
7606 representation of the arguments so that their form can be
7607 studied. In any cases, the appropriate type conversions
7608 should be put back in the tree that will get out of the
7609 constant folder. */
7611 }
7614 {
7617 {
7621 }
7622 }
7623 }
7630 {
7637 {
7651 /* If this was a conversion, and all we did was to move into
7652 inside the COND_EXPR, bring it back out. But leave it if
7653 it is a conversion from integer to integer and the
7654 result precision is no wider than a word since such a
7655 conversion is cheap and may be optimized away by combine,
7656 while it couldn't if it were outside the COND_EXPR. Then return
7657 so we don't get into an infinite recursion loop taking the
7658 conversion out and then back in. */
7670 && (INTEGRAL_TYPE_P
7683 }
7684 }
7687 {
7693 CASE_CONVERT:
7697 {
7698 /* If we have (type) (a CMP b) and type is an integral type, return
7699 new expression involving the new type. Canonicalize
7700 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7701 non-integral type.
7702 Do not fold the result as that would not simplify further, also
7703 folding again results in recursions. */
7713 }
7715 /* Handle (T *)&A.B.C for A being of type T and B and C
7716 living at offset zero. This occurs frequently in
7717 C++ upcasting and then accessing the base. */
7721 {
7723 tree offset;
7724 machine_mode mode;
7726 tree base
7730 /* If the reference was to a (constant) zero offset, we can use
7731 the address of the base if it has the same base type
7732 as the result type and the pointer type is unqualified. */
7739 }
7743 /* Detect assigning a bitfield. */
7745 && DECL_BIT_FIELD
7747 {
7748 /* Don't leave an assignment inside a conversion
7749 unless assigning a bitfield. */
7751 /* First do the assignment, then return converted constant. */
7756 }
7758 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7759 constants (if x has signed type, the sign bit cannot be set
7760 in c). This folds extension into the BIT_AND_EXPR.
7761 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7762 very likely don't have maximal range for their precision and this
7763 transformation effectively doesn't preserve non-maximal ranges. */
7767 {
7778 <= HOST_BITS_PER_WIDE_INT
7780 {
7784 cst &= HOST_WIDE_INT_M1U
7788 && !flag_syntax_only
7791 {
7795 }
7796 }
7798 {
7803 }
7804 }
7806 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7807 cast (T1)X will fold away. We assume that this happens when X itself
7808 is a cast. */
7812 {
7816 return fold_build_pointer_plus_loc
7818 }
7820 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7821 of the same precision, and X is an integer type not narrower than
7822 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7828 {
7834 }
7836 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7837 type of X and Y (integer types only). */
7842 {
7843 /* Be careful not to introduce new overflows. */
7844 tree mult_type;
7847 else
7851 {
7858 }
7859 }
7865 {
7870 }
7881 /* Convert fabs((double)float) into (double)fabsf(float). */
7884 {
7890 targ0));
7891 }
7895 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7914 /* Note that the operand of this must be an int
7915 and its values must be 0 or 1.
7916 ("true" is a fixed value perhaps depending on the language,
7917 but we don't handle values other than 1 correctly yet.) */
7924 /* Fold *&X to X if X is an lvalue. */
7926 {
7933 }
7939 }
7942 /* If the operation was a conversion do _not_ mark a resulting constant
7943 with TREE_OVERFLOW if the original constant was not. These conversions
7944 have implementation defined behavior and retaining the TREE_OVERFLOW
7945 flag here would confuse later passes such as VRP. */
7946 tree
7949 {
7958 }
7960 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7961 operands OP0 and OP1. LOC is the location of the resulting expression.
7962 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7963 Return the folded expression if folding is successful. Otherwise,
7964 return NULL_TREE. */
7965 static tree
7968 {
7969 tree tem;
7971 /* We only do these simplifications if we are optimizing. */
7975 /* Check for things like (A || B) && (A || C). We can convert this
7976 to A || (B && C). Note that either operator can be any of the four
7977 truth and/or operations and the transformation will still be
7978 valid. Also note that we only care about order for the
7979 ANDIF and ORIF operators. If B contains side effects, this
7980 might change the truth-value of A. */
7987 {
8007 /* This case if tricky because we must either have commutative
8008 operators or else A10 must not have side-effects. */
8014 a01);
8015 }
8017 /* See if we can build a range comparison. */
8023 {
8027 }
8031 {
8035 }
8037 /* Check for the possibility of merging component references. If our
8038 lhs is another similar operation, try to merge its rhs with our
8039 rhs. Then try to merge our lhs and rhs. */
8053 {
8060 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8061 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8062 We don't want to pack more than two leafs to a non-IF AND/OR
8063 expression.
8064 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8065 equal to IF-CODE, then we don't want to add right-hand operand.
8066 If the inner right-hand side of left-hand operand has
8067 side-effects, or isn't simple, then we can't add to it,
8068 as otherwise we might destroy if-sequence. */
8071 /* Needed for sequence points to handle trappings, and
8072 side-effects. */
8074 {
8076 arg1);
8078 tem);
8079 }
8080 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8081 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8084 /* Needed for sequence points to handle trappings, and
8085 side-effects. */
8087 {
8092 }
8093 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8094 into (A OR B).
8095 For sequence point consistancy, we need to check for trapping,
8096 and side-effects. */
8100 }
8103 }
8105 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8106 by changing CODE to reduce the magnitude of constants involved in
8107 ARG0 of the comparison.
8108 Returns a canonicalized comparison tree if a simplification was
8109 possible, otherwise returns NULL_TREE.
8110 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8111 valid if signed overflow is undefined. */
8113 static tree
8117 {
8122 /* Match A +- CST code arg1. We can change this only if overflow
8123 is undefined. */
8126 /* In principle pointers also have undefined overflow behavior,
8127 but that causes problems elsewhere. */
8134 /* Identify the constant in arg0 and its sign. */
8138 /* Overflowed constants and zero will cause problems. */
8143 /* See if we can reduce the magnitude of the constant in
8144 arg0 by changing the comparison code. */
8145 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8149 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8153 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8157 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8161 else
8165 /* Now build the constant reduced in magnitude. But not if that
8166 would produce one outside of its types range. */
8182 }
8184 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8185 overflow further. Try to decrease the magnitude of constants involved
8186 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8187 and put sole constants at the second argument position.
8188 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8190 static tree
8193 {
8194 tree t;
8199 /* Try canonicalization by simplifying arg0. */
8204 {
8208 }
8210 /* Try canonicalization by simplifying arg1 using the swapped
8211 comparison. */
8219 }
8221 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8222 space. This is used to avoid issuing overflow warnings for
8223 expressions like &p->x which can not wrap. */
8225 static bool
8227 {
8234 wide_int wi_offset;
8240 else
8256 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8257 array. */
8259 {
8260 HOST_WIDE_INT base_size;
8265 }
8268 }
8270 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8271 kind INTEGER_CST. This makes sure to properly sign-extend the
8272 constant. */
8274 static HOST_WIDE_INT
8276 {
8282 }
8284 /* Subroutine of fold_binary. This routine performs all of the
8285 transformations that are common to the equality/inequality
8286 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8287 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8288 fold_binary should call fold_binary. Fold a comparison with
8289 tree code CODE and type TYPE with operands OP0 and OP1. Return
8290 the folded comparison or NULL_TREE. */
8292 static tree
8295 {
8305 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8307 && (equality_code
8314 {
8315 const enum tree_code
8322 /* If the constant operation overflowed this can be
8323 simplified as a comparison against INT_MAX/INT_MIN. */
8326 {
8330 /* Get the sign of the constant on the lhs if the
8331 operation were VARIABLE + CONST1. */
8335 /* The sign of the constant determines if we overflowed
8336 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8337 Canonicalize to the INT_MIN overflow by swapping the comparison
8338 if necessary. */
8342 /* We now can look at the canonicalized case
8343 VARIABLE + 1 CODE2 INT_MIN
8344 and decide on the result. */
8346 {
8350 return
8356 return
8361 }
8362 }
8363 else
8364 {
8367 "when changing X +- C1 cmp C2 to "
8369 WARN_STRICT_OVERFLOW_COMPARISON);
8371 }
8372 }
8374 /* For comparisons of pointers we can decompose it to a compile time
8375 comparison of the base objects and the offsets into the object.
8376 This requires at least one operand being an ADDR_EXPR or a
8377 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8383 {
8386 machine_mode mode;
8390 /* Get base and offset for the access. Strip ADDR_EXPR for
8391 get_inner_reference, but put it back by stripping INDIRECT_REF
8392 off the base object if possible. indirect_baseN will be true
8393 if baseN is not an address but refers to the object itself. */
8396 {
8397 base0
8403 else
8405 }
8407 {
8411 {
8414 }
8417 {
8422 {
8425 }
8426 }
8427 }
8431 {
8432 base1
8438 else
8440 }
8442 {
8446 {
8449 }
8452 {
8457 {
8460 }
8461 }
8462 }
8464 /* If we have equivalent bases we might be able to simplify. */
8468 {
8469 /* We can fold this expression to a constant if the non-constant
8470 offset parts are equal. */
8479 {
8485 "occur when comparing P +- C1 with "
8487 WARN_STRICT_OVERFLOW_CONDITIONAL);
8490 {
8504 }
8505 }
8506 /* We can simplify the comparison to a comparison of the variable
8507 offset parts if the constant offset parts are equal.
8508 Be careful to use signed sizetype here because otherwise we
8509 mess with array offsets in the wrong way. This is possible
8510 because pointer arithmetic is restricted to retain within an
8511 object and overflow on pointer differences is undefined as of
8512 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8514 && (equality_code
8517 {
8518 /* By converting to signed sizetype we cover middle-end pointer
8519 arithmetic which operates on unsigned pointer types of size
8520 type size and ARRAY_REF offsets which are properly sign or
8521 zero extended from their type in case it is narrower than
8522 sizetype. */
8525 else
8529 else
8536 "occur when comparing P +- C1 with "
8538 WARN_STRICT_OVERFLOW_COMPARISON);
8541 }
8542 }
8543 /* For equal offsets we can simplify to a comparison of the
8544 base addresses. */
8546 && (indirect_base0
8548 && (indirect_base1
8553 {
8559 }
8560 }
8562 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8563 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8564 the resulting offset is smaller in absolute value than the
8565 original one and has the same sign. */
8574 {
8579 tree cst;
8581 "occur when combining constants around "
8584 /* Put the constant on the side where it doesn't overflow and is
8585 of lower absolute value and of same sign than before. */
8592 {
8595 variable1,
8599 }
8607 {
8613 variable2);
8614 }
8615 }
8621 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8622 constant, we can simplify it. */
8627 {
8631 }
8633 /* If we are comparing an expression that just has comparisons
8634 of two integer values, arithmetic expressions of those comparisons,
8635 and constants, we can simplify it. There are only three cases
8636 to check: the two values can either be equal, the first can be
8637 greater, or the second can be greater. Fold the expression for
8638 those three values. Since each value must be 0 or 1, we have
8639 eight possibilities, each of which corresponds to the constant 0
8640 or 1 or one of the six possible comparisons.
8642 This handles common cases like (a > b) == 0 but also handles
8643 expressions like ((x > y) - (y > x)) > 0, which supposedly
8644 occur in macroized code. */
8647 {
8652 /* Don't handle degenerate cases here; they should already
8653 have been handled anyway. */
8662 {
8666 /* We can't just pass T to eval_subst in case cval1 or cval2
8667 was the same as ARG1. */
8669 tree high_result
8673 arg1);
8674 tree equal_result
8678 arg1);
8679 tree low_result
8683 arg1);
8685 /* All three of these results should be 0 or 1. Confirm they are.
8686 Then use those values to select the proper code to use. */
8691 {
8692 /* Make a 3-bit mask with the high-order bit being the
8693 value for `>', the next for '=', and the low for '<'. */
8697 {
8699 /* Always false. */
8720 /* Always true. */
8722 }
8725 {
8729 }
8731 }
8732 }
8733 }
8735 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8736 into a single range test. */
8744 {
8748 }
8751 }
8754 /* Subroutine of fold_binary. Optimize complex multiplications of the
8755 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8756 argument EXPR represents the expression "z" of type TYPE. */
8758 static tree
8760 {
8765 {
8768 }
8770 {
8773 }
8774 else
8775 {
8779 }
8788 }
8791 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8792 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8794 static bool
8796 {
8800 {
8803 }
8805 {
8811 else
8813 }
8814 else
8820 }
8822 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8823 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8824 NULL_TREE otherwise. */
8826 static tree
8828 {
8845 {
8849 }
8852 {
8858 }
8859 else
8861 }
8863 /* Try to fold a pointer difference of type TYPE two address expressions of
8864 array references AREF0 and AREF1 using location LOC. Return a
8865 simplified expression for the difference or NULL_TREE. */
8867 static tree
8870 {
8875 /* If the bases are array references as well, recurse. If the bases
8876 are pointer indirections compute the difference of the pointers.
8877 If the bases are equal, we are set. */
8880 && (base_offset
8884 && (base_offset
8890 {
8896 base_offset,
8899 }
8901 }
8903 /* If the real or vector real constant CST of type TYPE has an exact
8904 inverse, return it, else return NULL. */
8906 tree
8908 {
8909 REAL_VALUE_TYPE r;
8911 machine_mode mode;
8915 {
8931 {
8936 }
8942 }
8943 }
8945 /* Mask out the tz least significant bits of X of type TYPE where
8946 tz is the number of trailing zeroes in Y. */
8947 static wide_int
8949 {
8954 }
8956 /* Return true when T is an address and is known to be nonzero.
8957 For floating point we further ensure that T is not denormal.
8958 Similar logic is present in nonzero_address in rtlanal.h.
8960 If the return value is based on the assumption that signed overflow
8961 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8962 change *STRICT_OVERFLOW_P. */
8964 static bool
8966 {
8970 /* Doing something useful for floating point would need more work. */
8976 {
8979 strict_overflow_p);
8985 strict_overflow_p);
8993 }
8996 {
8999 strict_overflow_p);
9007 strict_overflow_p);
9022 strict_overflow_p);
9026 strict_overflow_p);
9029 {
9041 }
9045 }
9047 }
9049 /* Return true when T is an address and is known to be nonzero.
9050 Handle warnings about undefined signed overflow. */
9052 static bool
9054 {
9061 "determining that expression is always "
9063 WARN_STRICT_OVERFLOW_MISC);
9065 }
9067 /* Fold a binary expression of code CODE and type TYPE with operands
9068 OP0 and OP1. LOC is the location of the resulting expression.
9069 Return the folded expression if folding is successful. Otherwise,
9070 return NULL_TREE. */
9072 tree
9075 {
9090 /* Strip any conversions that don't change the mode. This is
9091 safe for every expression, except for a comparison expression
9092 because its signedness is derived from its operands. So, in
9093 the latter case, only strip conversions that don't change the
9094 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9095 preserved.
9097 Note that this is done as an internal manipulation within the
9098 constant folder, in order to find the simplest representation
9099 of the arguments so that their form can be studied. In any
9100 cases, the appropriate type conversions should be put back in
9101 the tree that will get out of the constant folder. */
9104 {
9107 }
9108 else
9109 {
9112 }
9114 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9115 constant but we can't do arithmetic on them. */
9117 {
9120 {
9124 }
9125 }
9127 /* If this is a commutative operation, and ARG0 is a constant, move it
9128 to ARG1 to reduce the number of tests below. */
9133 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9134 to ARG1 to reduce the number of tests below. */
9143 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9145 First check for cases where an arithmetic operation is applied to a
9146 compound, conditional, or comparison operation. Push the arithmetic
9147 operation inside the compound or conditional to see if any folding
9148 can then be done. Convert comparison to conditional for this purpose.
9149 The also optimizes non-constant cases that used to be done in
9150 expand_expr.
9152 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9153 one of the operands is a comparison and the other is a comparison, a
9154 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9155 code below would make the expression more complex. Change it to a
9156 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9157 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9170 {
9174 boolean_type_node,
9182 }
9186 {
9188 {
9193 tem);
9194 }
9197 {
9202 tem);
9203 }
9208 {
9214 }
9219 {
9225 }
9226 }
9229 {
9231 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9234 {
9240 }
9242 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9245 {
9246 tree base;
9247 HOST_WIDE_INT coffset;
9256 }
9261 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9267 arg1),
9269 arg0)));
9275 {
9276 /* X + (X / CST) * -CST is X % CST. */
9281 {
9290 cst0));
9291 }
9292 }
9294 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9295 one. Make sure the type is not saturating and has the signedness of
9296 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9297 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9304 {
9308 }
9311 {
9312 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9313 (plus (plus (mult) (mult)) (foo)) so that we can
9314 take advantage of the factoring cases below. */
9323 {
9329 else
9342 parg0),
9344 marg)),
9348 return
9354 parg1)));
9355 }
9356 }
9357 else
9358 {
9359 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9360 to __complex__ ( x, y ). This is not the same for SNaNs or
9361 if signed zeros are involved. */
9365 {
9372 {
9376 {
9382 }
9384 {
9390 }
9391 }
9392 }
9400 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9401 We associate floats only if the user has specified
9402 -fassociative-math. */
9406 {
9411 {
9412 tree tree0;
9415 }
9416 }
9417 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9418 We associate floats only if the user has specified
9419 -fassociative-math. */
9423 {
9428 {
9429 tree tree0;
9432 }
9433 }
9434 }
9436 bit_rotate:
9437 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9438 is a rotate of A by C1 bits. */
9439 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9440 is a rotate of A by B bits. */
9441 {
9443 tree rtype;
9452 /* Only create rotates in complete modes. Other cases are not
9453 expanded properly. */
9456 {
9470 {
9474 code0 == LSHIFT_EXPR
9478 }
9480 {
9488 element_precision
9492 return
9495 ? LROTATE_EXPR
9500 }
9502 {
9510 element_precision
9514 return fold_convert_loc
9517 ? LROTATE_EXPR
9521 }
9522 }
9523 }
9525 associate:
9526 /* In most languages, can't associate operations on floats through
9527 parentheses. Rather than remember where the parentheses were, we
9528 don't associate floats at all, unless the user has specified
9529 -fassociative-math.
9530 And, we need to make sure type is not saturating. */
9534 {
9540 /* Split both trees into variables, constants, and literals. Then
9541 associate each group together, the constants with literals,
9542 then the result with variables. This increases the chances of
9543 literals being recombined later and of generating relocatable
9544 expressions for the sum of a constant and literal. */
9549 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9553 /* With undefined overflow prefer doing association in a type
9554 which wraps on overflow, if that is one of the operand types. */
9557 {
9565 }
9567 /* With undefined overflow we can only associate constants with one
9568 variable, and constants whose association doesn't overflow. */
9571 {
9573 {
9579 {
9582 }
9589 {
9592 }
9598 /* The only case we can still associate with two variables
9599 is if they cancel out. */
9603 }
9604 }
9606 /* Only do something if we found more than two objects. Otherwise,
9607 nothing has changed and we risk infinite recursion. */
9613 {
9625 /* Preserve the MINUS_EXPR if the negative part of the literal is
9626 greater than the positive part. Otherwise, the multiplicative
9627 folding code (i.e extract_muldiv) may be fooled in case
9628 unsigned constants are subtracted, like in the following
9629 example: ((X*2 + 4) - 8U)/2. */
9631 {
9635 {
9639 }
9640 else
9641 {
9645 }
9646 }
9648 /* Don't introduce overflows through reassociation. */
9655 {
9657 return
9661 else
9662 {
9665 return
9669 }
9670 }
9673 return
9676 }
9677 }
9682 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9691 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9692 __complex__ ( x, -y ). This is not the same for SNaNs or if
9693 signed zeros are involved. */
9697 {
9704 {
9708 {
9710 arg1r ? arg1r
9715 }
9717 {
9721 arg1i ? arg1i
9724 }
9725 }
9726 }
9728 /* A - B -> A + (-B) if B is easily negatable. */
9732 /* Avoid this transformation if B is a positive REAL_CST. */
9740 /* Fold &a[i] - &a[j] to i-j. */
9745 {
9751 }
9754 && flag_unsafe_math_optimizations
9760 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9761 one. Make sure the type is not saturating and has the signedness of
9762 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9763 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9770 {
9774 }
9780 {
9781 /* Transform x * -C into -x * C if x is easily negatable. */
9791 /* (A + A) * C -> A * 2 * C */
9803 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9804 sign-changing only. */
9814 {
9817 "occur when simplifying "
9819 WARN_STRICT_OVERFLOW_MISC);
9821 }
9823 /* Optimize z * conj(z) for integer complex numbers. */
9830 }
9831 else
9832 {
9833 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9834 This is not the same for NaNs or if signed zeros are
9835 involved. */
9841 {
9844 return
9850 return
9855 }
9857 /* Optimize z * conj(z) for floating point complex numbers.
9858 Guarded by flag_unsafe_math_optimizations as non-finite
9859 imaginary components don't produce scalar results. */
9870 {
9872 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
9874 && optimize
9876 {
9880 {
9883 }
9884 }
9885 }
9886 }
9890 /* Canonicalize (X & C1) | C2. */
9894 {
9899 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9907 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9912 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9913 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9914 mode which allows further optimizations. */
9919 {
9923 {
9926 }
9927 }
9934 c3)),
9935 arg1);
9936 }
9938 /* See if this can be simplified into a rotate first. If that
9939 is unsuccessful continue in the association code. */
9943 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9951 /* See if this can be simplified into a rotate first. If that
9952 is unsuccessful continue in the association code. */
9956 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9961 {
9962 tree tem2;
9969 }
9970 /* Fold ~X & 1 as (X & 1) == 0. */
9974 {
9975 tree tem2;
9982 }
9983 /* Fold !X & 1 as X == 0. */
9986 {
9990 }
9992 /* Fold (X ^ Y) & Y as ~X & Y. */
9995 {
10000 }
10001 /* Fold (X ^ Y) & X as ~Y & X. */
10005 {
10010 }
10011 /* Fold X & (X ^ Y) as X & ~Y. */
10014 {
10019 }
10020 /* Fold X & (Y ^ X) as ~Y & X. */
10024 {
10029 }
10031 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10032 multiple of 1 << CST. */
10034 {
10041 }
10043 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10044 bits from CST2. */
10048 {
10056 {
10057 /* Avoid the transform if arg1 is a mask of some
10058 mode which allows further optimizations. */
10065 }
10066 }
10068 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10069 ((A & N) + B) & M -> (A + B) & M
10070 Similarly if (N & M) == 0,
10071 ((A | N) + B) & M -> (A + B) & M
10072 and for - instead of + (or unary - instead of +)
10073 and/or ^ instead of |.
10074 If B is constant and (B & M) == 0, fold into A & M. */
10076 {
10085 {
10088 wide_int cst0;
10090 /* Now we know that arg0 is (C + D) or (C - D) or
10091 -C and arg1 (M) is == (1LL << cst) - 1.
10092 Store C into PMOP[0] and D into PMOP[1]. */
10096 {
10099 }
10106 {
10116 {
10119 }
10122 /* If C or D is of the form (A & N) where
10123 (N & M) == M, or of the form (A | N) or
10124 (A ^ N) where (N & M) == 0, replace it with A. */
10128 /* If C or D is a N where (N & M) == 0, it can be
10129 omitted (assumed 0). */
10137 }
10139 /* Only build anything new if we optimized one or both arguments
10140 above. */
10144 {
10147 {
10148 /* Perform the operations in a type that has defined
10149 overflow behavior. */
10155 }
10160 {
10168 else
10170 }
10173 else
10176 /* TEM is now the new binary +, - or unary - replacement. */
10180 }
10181 }
10182 }
10184 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10187 {
10192 return
10194 }
10199 /* Don't touch a floating-point divide by zero unless the mode
10200 of the constant can represent infinity. */
10206 /* (-A) / (-B) -> A / B */
10218 /* Fall through */
10221 /* Simplify A / (B << N) where A and B are positive and B is
10222 a power of 2, to A >> (N + log2(B)). */
10227 {
10230 {
10238 WARN_STRICT_OVERFLOW_MISC);
10244 }
10245 }
10247 /* Fall through */
10255 /* Convert -A / -B to A / B when the type is signed and overflow is
10256 undefined. */
10260 {
10263 "when distributing negation across "
10265 WARN_STRICT_OVERFLOW_MISC);
10270 }
10274 {
10277 "when distributing negation across "
10279 WARN_STRICT_OVERFLOW_MISC);
10284 }
10286 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10287 operation, EXACT_DIV_EXPR.
10289 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10290 At one time others generated faster code, it's not clear if they do
10291 after the last round to changes to the DIV code in expmed.c. */
10302 {
10306 WARN_STRICT_OVERFLOW_MISC);
10308 }
10320 {
10324 WARN_STRICT_OVERFLOW_MISC);
10326 }
10334 /* Since negative shift count is not well-defined,
10335 don't try to compute it in the compiler. */
10341 /* If we have a rotate of a bit operation with the rotate count and
10342 the second operand of the bit operation both constant,
10343 permute the two operations. */
10355 /* Two consecutive rotates adding up to the some integer
10356 multiple of the precision of the type can be ignored. */
10371 /* Note that the operands of this must be ints
10372 and their values must be 0 or 1.
10373 ("true" is a fixed value perhaps depending on the language.) */
10374 /* If first arg is constant zero, return it. */
10378 /* If either arg is constant true, drop it. */
10382 /* Preserve sequence points. */
10385 /* If second arg is constant zero, result is zero, but first arg
10386 must be evaluated. */
10389 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10390 case will be handled here. */
10394 /* !X && X is always false. */
10398 /* X && !X is always false. */
10403 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10404 means A >= Y && A != MAX, but in this case we know that
10405 A < X <= MAX. */
10409 {
10417 }
10426 /* Note that the operands of this must be ints
10427 and their values must be 0 or true.
10428 ("true" is a fixed value perhaps depending on the language.) */
10429 /* If first arg is constant true, return it. */
10433 /* If either arg is constant zero, drop it. */
10437 /* Preserve sequence points. */
10440 /* If second arg is constant true, result is true, but we must
10441 evaluate first arg. */
10444 /* Likewise for first arg, but note this only occurs here for
10445 TRUTH_OR_EXPR. */
10449 /* !X || X is always true. */
10453 /* X || !X is always true. */
10458 /* (X && !Y) || (!X && Y) is X ^ Y */
10461 {
10478 }
10487 /* If the second arg is constant zero, drop it. */
10490 /* If the second arg is constant true, this is a logical inversion. */
10492 {
10495 }
10496 /* Identical arguments cancel to zero. */
10500 /* !X ^ X is always true. */
10505 /* X ^ !X is always true. */
10521 /* bool_var != 1 becomes !bool_var. */
10528 /* bool_var == 0 becomes !bool_var. */
10535 /* !exp != 0 becomes !exp */
10540 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10549 {
10553 val,
10557 }
10559 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10566 {
10568 code == NE_EXPR
10571 }
10573 /* If this is an EQ or NE comparison with zero and ARG0 is
10574 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10575 two operations, but the latter can be done in one less insn
10576 on machines that have only two-operand insns or on which a
10577 constant cannot be the first operand. */
10580 {
10585 {
10592 arg1);
10593 }
10596 {
10603 arg1);
10604 }
10605 }
10607 /* If this is an NE or EQ comparison of zero against the result of a
10608 signed MOD operation whose second operand is a power of 2, make
10609 the MOD operation unsigned since it is simpler and equivalent. */
10617 {
10627 }
10629 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10630 C1 is a valid shift constant, and C2 is a power of two, i.e.
10631 a single bit. */
10635 == INTEGER_CST
10638 {
10643 /* Check for a valid shift count. */
10645 {
10649 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10650 can be rewritten as (X & (C2 << C1)) != 0. */
10652 {
10657 }
10658 /* Otherwise, for signed (arithmetic) shifts,
10659 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10660 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10664 /* Otherwise, of unsigned (logical) shifts,
10665 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10666 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10667 else
10671 arg000);
10672 }
10673 }
10675 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10676 Similarly for NE_EXPR. */
10680 {
10684 tree dandnotc
10687 notc);
10691 }
10693 /* If this is a comparison of a field, we may be able to simplify it. */
10696 /* Handle the constant case even without -O
10697 to make sure the warnings are given. */
10699 {
10703 }
10705 /* Optimize comparisons of strlen vs zero to a compare of the
10706 first character of the string vs zero. To wit,
10707 strlen(ptr) == 0 => *ptr == 0
10708 strlen(ptr) != 0 => *ptr != 0
10709 Other cases should reduce to one of these two (or a constant)
10710 due to the return value of strlen being unsigned. */
10713 {
10721 {
10726 }
10727 }
10729 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10730 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10734 {
10739 {
10741 {
10744 }
10747 }
10748 }
10750 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10751 (X & C) == 0 when C is a single bit. */
10756 {
10763 arg1));
10764 }
10766 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10767 constant C is a power of two, i.e. a single bit. */
10774 {
10778 }
10780 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10781 when is C is a power of two, i.e. a single bit. */
10788 {
10794 }
10798 {
10801 }
10803 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10806 {
10819 arg01),
10828 arg01),
10837 arg00),
10846 arg00),
10848 }
10852 {
10859 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10860 operand_equal_p guarantees no side-effects so we don't need
10861 to use omit_one_operand on Z. */
10865 arg10));
10869 arg11));
10873 arg10));
10877 arg11));
10879 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10882 {
10888 }
10889 }
10891 /* Attempt to simplify equality/inequality comparisons of complex
10892 values. Only lower the comparison if the result is known or
10893 can be simplified to a single scalar comparison. */
10898 {
10903 {
10906 }
10907 else
10908 {
10911 }
10914 {
10917 }
10918 else
10919 {
10922 }
10926 {
10928 {
10933 }
10934 else
10935 {
10940 }
10941 }
10945 {
10947 {
10952 }
10953 else
10954 {
10959 }
10960 }
10961 }
10973 /* Transform comparisons of the form X +- C CMP X. */
10980 {
10987 else
10990 /* (X - c) > X becomes false. */
10994 {
10998 "occur when assuming that (X - c) > X "
11000 WARN_STRICT_OVERFLOW_ALL);
11002 }
11004 /* Likewise (X + c) < X becomes false. */
11008 {
11012 "occur when assuming that "
11014 WARN_STRICT_OVERFLOW_ALL);
11016 }
11018 /* Convert (X - c) <= X to true. */
11023 {
11027 "occur when assuming that "
11029 WARN_STRICT_OVERFLOW_ALL);
11031 }
11033 /* Convert (X + c) >= X to true. */
11038 {
11042 "occur when assuming that "
11044 WARN_STRICT_OVERFLOW_ALL);
11046 }
11049 {
11050 /* Convert X + c > X and X - c < X to true for integers. */
11054 {
11057 "not occur when assuming that "
11059 WARN_STRICT_OVERFLOW_ALL);
11061 }
11066 {
11069 "not occur when assuming that "
11071 WARN_STRICT_OVERFLOW_ALL);
11073 }
11075 /* Convert X + c <= X and X - c >= X to false for integers. */
11079 {
11082 "not occur when assuming that "
11084 WARN_STRICT_OVERFLOW_ALL);
11086 }
11091 {
11094 "not occur when assuming that "
11096 WARN_STRICT_OVERFLOW_ALL);
11098 }
11099 }
11100 }
11102 /* If we are comparing an ABS_EXPR with a constant, we can
11103 convert all the cases into explicit comparisons, but they may
11104 well not be faster than doing the ABS and one comparison.
11105 But ABS (X) <= C is a range comparison, which becomes a subtraction
11106 and a comparison, and is probably faster. */
11120 /* Convert ABS_EXPR<x> >= 0 to true. */
11127 {
11130 "when simplifying comparison of "
11132 WARN_STRICT_OVERFLOW_CONDITIONAL);
11135 arg0);
11136 }
11138 /* Convert ABS_EXPR<x> < 0 to false. */
11143 {
11146 "when simplifying comparison of "
11148 WARN_STRICT_OVERFLOW_CONDITIONAL);
11151 arg0);
11152 }
11154 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11155 and similarly for >= into !=. */
11165 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11166 otherwise Y might be >= # of bits in X's type and thus e.g.
11167 (unsigned char) (1 << Y) for Y 15 might be 0.
11168 If the cast is widening, then 1 << Y should have unsigned type,
11169 otherwise if Y is number of bits in the signed shift type minus 1,
11170 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11171 31 might be 0xffffffff80000000. */
11182 {
11188 }
11200 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11201 {
11213 }
11218 /* When pedantic, a compound expression can be neither an lvalue
11219 nor an integer constant expression. */
11222 /* Don't let (0, 0) be null pointer constant. */
11228 /* An ASSERT_EXPR should never be passed to fold_binary. */
11234 }
11236 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11237 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11238 of GOTO_EXPR. */
11240 static tree
11242 {
11244 {
11251 /* ... fall through ... */
11255 }
11256 }
11258 /* Return whether the sub-tree ST contains a label which is accessible from
11259 outside the sub-tree. */
11261 static bool
11263 {
11264 return
11266 }
11268 /* Fold a ternary expression of code CODE and type TYPE with operands
11269 OP0, OP1, and OP2. Return the folded expression if folding is
11270 successful. Otherwise, return NULL_TREE. */
11272 tree
11275 {
11276 tree tem;
11283 /* If this is a commutative operation, and OP0 is a constant, move it
11284 to OP1 to reduce the number of tests below. */
11293 /* Strip any conversions that don't change the mode. This is safe
11294 for every expression, except for a comparison expression because
11295 its signedness is derived from its operands. So, in the latter
11296 case, only strip conversions that don't change the signedness.
11298 Note that this is done as an internal manipulation within the
11299 constant folder, in order to find the simplest representation of
11300 the arguments so that their form can be studied. In any cases,
11301 the appropriate type conversions should be put back in the tree
11302 that will get out of the constant folder. */
11304 {
11307 }
11310 {
11313 }
11316 {
11319 }
11322 {
11326 {
11332 }
11337 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11338 so all simple results must be passed through pedantic_non_lvalue. */
11340 {
11343 /* Only optimize constant conditions when the selected branch
11344 has the same type as the COND_EXPR. This avoids optimizing
11345 away "c ? x : throw", where the throw has a void type.
11346 Avoid throwing away that operand which contains label. */
11353 }
11355 {
11360 {
11365 {
11373 }
11377 }
11378 }
11380 /* If we have A op B ? A : C, we may be able to convert this to a
11381 simpler expression, depending on the operation and the values
11382 of B and C. Signed zeros prevent all of these transformations,
11383 for reasons given above each one.
11385 Also try swapping the arguments and inverting the conditional. */
11390 {
11394 }
11398 op2,
11401 {
11405 {
11409 }
11410 }
11412 /* If the second operand is simpler than the third, swap them
11413 since that produces better jump optimization results. */
11416 {
11418 /* See if this can be inverted. If it can't, possibly because
11419 it was a floating-point inequality comparison, don't do
11420 anything. */
11424 }
11426 /* Convert A ? 1 : 0 to simply A. */
11431 /* If we try to convert OP0 to our type, the
11432 call to fold will try to move the conversion inside
11433 a COND, which will recurse. In that case, the COND_EXPR
11434 is probably the best choice, so leave it alone. */
11438 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11439 over COND_EXPR in cases such as floating point comparisons. */
11448 arg0)));
11450 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11455 {
11456 /* sign_bit_p looks through both zero and sign extensions,
11457 but for this optimization only sign extensions are
11458 usable. */
11461 {
11464 {
11467 }
11469 }
11470 /* sign_bit_p only checks ARG1 bits within A's precision.
11471 If <sign bit of A> has wider type than A, bits outside
11472 of A's precision in <sign bit of A> need to be checked.
11473 If they are all 0, this optimization needs to be done
11474 in unsigned A's type, if they are all 1 in signed A's type,
11475 otherwise this can't be done. */
11481 {
11483 tree tem_type;
11496 {
11499 }
11501 {
11504 }
11505 else
11507 }
11510 return
11516 arg1)));
11517 }
11519 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11520 already handled above. */
11525 {
11534 }
11536 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11537 is probably obsolete because the first operand should be a
11538 truth value (that's why we have the two cases above), but let's
11539 leave it in until we can confirm this for all front-ends. */
11551 /* Disable the transformations below for vectors, since
11552 fold_binary_op_with_conditional_arg may undo them immediately,
11553 yielding an infinite loop. */
11557 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11566 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11571 {
11573 /* Only perform transformation if ARG0 is easily inverted. */
11577 ? BIT_IOR_EXPR
11580 arg1);
11581 }
11583 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11588 {
11590 /* Only perform transformation if ARG0 is easily inverted. */
11596 op2);
11597 }
11599 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11611 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11612 of fold_ternary on them. */
11622 {
11632 {
11637 {
11645 }
11647 /* Constructor elements can be subvectors. */
11650 {
11654 }
11656 /* We keep an exact subset of the constructor elements. */
11658 {
11664 {
11668 }
11676 CONSTRUCTOR_ELT
11679 }
11680 /* The bitfield references a single constructor element. */
11682 {
11687 else
11691 }
11692 }
11693 }
11695 /* A bit-field-ref that referenced the full argument can be stripped. */
11701 /* On constants we can use native encode/interpret to constant
11702 fold (nearly) all BIT_FIELD_REFs. */
11706 /* This limitation should not be necessary, we just need to
11707 round this up to mode size. */
11709 /* Need bit-shifting of the buffer to relax the following. */
11711 {
11716 /* ??? We cannot tell native_encode_expr to start at
11717 some random byte only. So limit us to a reasonable amount
11718 of work. */
11720 {
11725 {
11731 }
11732 }
11733 }
11738 /* For integers we can decompose the FMA if possible. */
11750 {
11766 {
11771 /* Make sure that the perm value is in an acceptable
11772 range. */
11781 else
11786 }
11789 {
11794 }
11799 {
11804 }
11810 {
11814 }
11819 /* Some targets are deficient and fail to expand a single
11820 argument permutation while still allowing an equivalent
11821 2-argument version. */
11825 {
11828 }
11831 {
11838 }
11842 }
11848 }
11850 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11851 of an array (or vector). */
11853 tree
11855 {
11860 {
11863 {
11864 /* Static constructors for variably sized objects makes no sense. */
11868 }
11869 }
11880 offset_int max_index;
11885 {
11886 /* Array constructor might explicitly set index, or specify a range,
11887 or leave index NULL meaning that it is next index after previous
11888 one. */
11890 {
11893 else
11894 {
11898 }
11899 }
11900 else
11901 {
11907 }
11909 /* Do we have match? */
11913 }
11915 }
11917 /* Perform constant folding and related simplification of EXPR.
11918 The related simplifications include x*1 => x, x*0 => 0, etc.,
11919 and application of the associative law.
11920 NOP_EXPR conversions may be removed freely (as long as we
11921 are careful not to change the type of the overall expression).
11922 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11923 but we can constant-fold them if they have constant operands. */
11925 #ifdef ENABLE_FOLD_CHECKING
11926 # define fold(x) fold_1 (x)
11928 static
11929 #endif
11930 tree
11932 {
11936 tree tem;
11939 /* Return right away if a constant. */
11943 /* CALL_EXPR-like objects with variable numbers of operands are
11944 treated specially. */
11946 {
11948 {
11951 }
11953 }
11956 {
11961 {
11979 }
11980 }
11983 {
11985 {
11992 {
11997 }
12000 }
12002 /* Return a VECTOR_CST if possible. */
12004 {
12010 tree val;
12016 }
12024 }
12026 #ifdef ENABLE_FOLD_CHECKING
12027 #undef fold
12034 /* When --enable-checking=fold, compute a digest of expr before
12035 and after actual fold call to see if fold did not accidentally
12036 change original expr. */
12038 tree
12040 {
12041 tree ret;
12061 }
12063 void
12065 {
12076 }
12078 static void
12080 {
12082 }
12084 static void
12087 {
12093 recursive_label:
12103 {
12104 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12109 }
12116 {
12117 /* Allow these fields to be modified. */
12118 tree tmp;
12126 {
12129 }
12130 }
12141 {
12144 {
12159 }
12163 {
12176 }
12193 {
12199 }
12202 {
12204 {
12207 }
12209 }
12220 {
12223 }
12233 }
12234 }
12236 /* Helper function for outputting the checksum of a tree T. When
12237 debugging with gdb, you can "define mynext" to be "next" followed
12238 by "call debug_fold_checksum (op0)", then just trace down till the
12239 outputs differ. */
12241 DEBUG_FUNCTION void
12243 {
12258 }
12260 #endif
12262 /* Fold a unary tree expression with code CODE of type TYPE with an
12263 operand OP0. LOC is the location of the resulting expression.
12264 Return a folded expression if successful. Otherwise, return a tree
12265 expression with code CODE of type TYPE with an operand OP0. */
12267 tree
12270 {
12271 tree tem;
12272 #ifdef ENABLE_FOLD_CHECKING
12281 #endif
12287 #ifdef ENABLE_FOLD_CHECKING
12294 #endif
12296 }
12298 /* Fold a binary tree expression with code CODE of type TYPE with
12299 operands OP0 and OP1. LOC is the location of the resulting
12300 expression. Return a folded expression if successful. Otherwise,
12301 return a tree expression with code CODE of type TYPE with operands
12302 OP0 and OP1. */
12304 tree
12307 MEM_STAT_DECL)
12308 {
12309 tree tem;
12310 #ifdef ENABLE_FOLD_CHECKING
12327 #endif
12333 #ifdef ENABLE_FOLD_CHECKING
12348 #endif
12350 }
12352 /* Fold a ternary tree expression with code CODE of type TYPE with
12353 operands OP0, OP1, and OP2. Return a folded expression if
12354 successful. Otherwise, return a tree expression with code CODE of
12355 type TYPE with operands OP0, OP1, and OP2. */
12357 tree
12360 {
12361 tree tem;
12362 #ifdef ENABLE_FOLD_CHECKING
12386 #endif
12393 #ifdef ENABLE_FOLD_CHECKING
12416 #endif
12418 }
12420 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12421 arguments in ARGARRAY, and a null static chain.
12422 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12423 of type TYPE from the given operands as constructed by build_call_array. */
12425 tree
12428 {
12429 tree tem;
12430 #ifdef ENABLE_FOLD_CHECKING
12449 #endif
12455 #ifdef ENABLE_FOLD_CHECKING
12471 #endif
12473 }
12475 /* Perform constant folding and related simplification of initializer
12476 expression EXPR. These behave identically to "fold_buildN" but ignore
12477 potential run-time traps and exceptions that fold must preserve. */
12479 #define START_FOLD_INIT \
12480 int saved_signaling_nans = flag_signaling_nans;\
12481 int saved_trapping_math = flag_trapping_math;\
12482 int saved_rounding_math = flag_rounding_math;\
12483 int saved_trapv = flag_trapv;\
12484 int saved_folding_initializer = folding_initializer;\
12485 flag_signaling_nans = 0;\
12486 flag_trapping_math = 0;\
12487 flag_rounding_math = 0;\
12488 flag_trapv = 0;\
12489 folding_initializer = 1;
12491 #define END_FOLD_INIT \
12492 flag_signaling_nans = saved_signaling_nans;\
12493 flag_trapping_math = saved_trapping_math;\
12494 flag_rounding_math = saved_rounding_math;\
12495 flag_trapv = saved_trapv;\
12496 folding_initializer = saved_folding_initializer;
12498 tree
12501 {
12502 tree result;
12503 START_FOLD_INIT;
12507 END_FOLD_INIT;
12509 }
12511 tree
12514 {
12515 tree result;
12516 START_FOLD_INIT;
12520 END_FOLD_INIT;
12522 }
12524 tree
12527 {
12528 tree result;
12529 START_FOLD_INIT;
12533 END_FOLD_INIT;
12535 }
12537 #undef START_FOLD_INIT
12538 #undef END_FOLD_INIT
12540 /* Determine if first argument is a multiple of second argument. Return 0 if
12541 it is not, or we cannot easily determined it to be.
12543 An example of the sort of thing we care about (at this point; this routine
12544 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12545 fold cases do now) is discovering that
12547 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12549 is a multiple of
12551 SAVE_EXPR (J * 8)
12553 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12555 This code also handles discovering that
12557 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12559 is a multiple of 8 so we don't have to worry about dealing with a
12560 possible remainder.
12562 Note that we *look* inside a SAVE_EXPR only to determine how it was
12563 calculated; it is not safe for fold to do much of anything else with the
12564 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12565 at run time. For example, the latter example above *cannot* be implemented
12566 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12567 evaluation time of the original SAVE_EXPR is not necessarily the same at
12568 the time the new expression is evaluated. The only optimization of this
12569 sort that would be valid is changing
12571 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12573 divided by 8 to
12575 SAVE_EXPR (I) * SAVE_EXPR (J)
12577 (where the same SAVE_EXPR (J) is used in the original and the
12578 transformed version). */
12580 int
12582 {
12590 {
12592 /* Bitwise and provides a power of two multiple. If the mask is
12593 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12596 /* FALLTHRU */
12609 {
12613 /* const_binop may not detect overflow correctly,
12614 so check for it explicitly here. */
12618 size_one_node,
12619 op1)))
12622 }
12626 /* Can't handle conversions from non-integral or wider integral type. */
12632 /* .. fall through ... */
12649 SIGNED);
12653 }
12654 }
12656 #define tree_expr_nonnegative_warnv_p(X, Y) \
12659 #define RECURSE(X) \
12660 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12662 /* Return true if CODE or TYPE is known to be non-negative. */
12664 static bool
12666 {
12669 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12670 have a signed:1 type (where the value is -1 and 0). */
12673 }
12675 /* Return true if (CODE OP0) is known to be non-negative. If the return
12676 value is based on the assumption that signed overflow is undefined,
12677 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12678 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12680 bool
12683 {
12688 {
12690 /* We can't return 1 if flag_wrapv is set because
12691 ABS_EXPR<INT_MIN> = INT_MIN. */
12695 {
12698 }
12706 CASE_CONVERT:
12707 {
12712 {
12716 {
12720 }
12721 }
12723 {
12729 }
12730 }
12735 }
12737 /* We don't know sign of `t', so be conservative and return false. */
12739 }
12741 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12742 value is based on the assumption that signed overflow is undefined,
12743 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12744 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12746 bool
12750 {
12755 {
12761 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12762 both unsigned and at least 2 bits shorter than the result. */
12766 {
12771 {
12775 }
12776 }
12781 {
12782 /* x * x is always non-negative for floating point x
12783 or without overflow. */
12786 {
12791 }
12792 }
12794 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12795 both unsigned and their total bits is shorter than the result. */
12799 {
12818 {
12828 }
12829 }
12856 }
12858 /* We don't know sign of `t', so be conservative and return false. */
12860 }
12862 /* Return true if T is known to be non-negative. If the return
12863 value is based on the assumption that signed overflow is undefined,
12864 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12865 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12867 bool
12869 {
12874 {
12888 /* Limit the depth of recursion to avoid quadratic behavior.
12889 This is expected to catch almost all occurrences in practice.
12890 If this code misses important cases that unbounded recursion
12891 would not, passes that need this information could be revised
12892 to provide it through dataflow propagation. */
12900 }
12901 }
12903 /* Return true if T is known to be non-negative. If the return
12904 value is based on the assumption that signed overflow is undefined,
12905 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12906 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12908 bool
12911 {
12913 {
12914 CASE_CFN_ACOS:
12915 CASE_CFN_ACOSH:
12916 CASE_CFN_CABS:
12917 CASE_CFN_COSH:
12918 CASE_CFN_ERFC:
12919 CASE_CFN_EXP:
12920 CASE_CFN_EXP10:
12921 CASE_CFN_EXP2:
12922 CASE_CFN_FABS:
12923 CASE_CFN_FDIM:
12924 CASE_CFN_HYPOT:
12925 CASE_CFN_POW10:
12926 CASE_CFN_FFS:
12927 CASE_CFN_PARITY:
12928 CASE_CFN_POPCOUNT:
12929 CASE_CFN_CLZ:
12930 CASE_CFN_CLRSB:
12933 /* Always true. */
12936 CASE_CFN_SQRT:
12937 /* sqrt(-0.0) is -0.0. */
12942 CASE_CFN_ASINH:
12943 CASE_CFN_ATAN:
12944 CASE_CFN_ATANH:
12945 CASE_CFN_CBRT:
12946 CASE_CFN_CEIL:
12947 CASE_CFN_ERF:
12948 CASE_CFN_EXPM1:
12949 CASE_CFN_FLOOR:
12950 CASE_CFN_FMOD:
12951 CASE_CFN_FREXP:
12952 CASE_CFN_ICEIL:
12953 CASE_CFN_IFLOOR:
12954 CASE_CFN_IRINT:
12955 CASE_CFN_IROUND:
12956 CASE_CFN_LCEIL:
12957 CASE_CFN_LDEXP:
12958 CASE_CFN_LFLOOR:
12959 CASE_CFN_LLCEIL:
12960 CASE_CFN_LLFLOOR:
12961 CASE_CFN_LLRINT:
12962 CASE_CFN_LLROUND:
12963 CASE_CFN_LRINT:
12964 CASE_CFN_LROUND:
12965 CASE_CFN_MODF:
12966 CASE_CFN_NEARBYINT:
12967 CASE_CFN_RINT:
12968 CASE_CFN_ROUND:
12969 CASE_CFN_SCALB:
12970 CASE_CFN_SCALBLN:
12971 CASE_CFN_SCALBN:
12972 CASE_CFN_SIGNBIT:
12973 CASE_CFN_SIGNIFICAND:
12974 CASE_CFN_SINH:
12975 CASE_CFN_TANH:
12976 CASE_CFN_TRUNC:
12977 /* True if the 1st argument is nonnegative. */
12980 CASE_CFN_FMAX:
12981 /* True if the 1st OR 2nd arguments are nonnegative. */
12984 CASE_CFN_FMIN:
12985 /* True if the 1st AND 2nd arguments are nonnegative. */
12988 CASE_CFN_COPYSIGN:
12989 /* True if the 2nd argument is nonnegative. */
12992 CASE_CFN_POWI:
12993 /* True if the 1st argument is nonnegative or the second
12994 argument is an even integer. */
13000 CASE_CFN_POW:
13001 /* True if the 1st argument is nonnegative or the second
13002 argument is an even integer valued real. */
13004 {
13005 REAL_VALUE_TYPE c;
13006 HOST_WIDE_INT n;
13011 {
13012 REAL_VALUE_TYPE cint;
13016 }
13017 }
13022 }
13024 }
13026 /* Return true if T is known to be non-negative. If the return
13027 value is based on the assumption that signed overflow is undefined,
13028 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13029 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13031 static bool
13033 {
13039 {
13041 {
13045 /* If the initializer is non-void, then it's a normal expression
13046 that will be assigned to the slot. */
13050 /* Otherwise, the initializer sets the slot in some way. One common
13051 way is an assignment statement at the end of the initializer. */
13053 {
13061 else
13063 }
13069 }
13072 {
13078 arg0,
13079 arg1,
13081 }
13094 }
13095 }
13097 #undef RECURSE
13098 #undef tree_expr_nonnegative_warnv_p
13100 /* Return true if T is known to be non-negative. If the return
13101 value is based on the assumption that signed overflow is undefined,
13102 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13103 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13105 bool
13107 {
13114 {
13136 }
13139 {
13165 }
13166 }
13168 /* Return true if `t' is known to be non-negative. Handle warnings
13169 about undefined signed overflow. */
13171 bool
13173 {
13180 "determining that expression is always "
13182 WARN_STRICT_OVERFLOW_MISC);
13184 }
13187 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13188 For floating point we further ensure that T is not denormal.
13189 Similar logic is present in nonzero_address in rtlanal.h.
13191 If the return value is based on the assumption that signed overflow
13192 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13193 change *STRICT_OVERFLOW_P. */
13195 bool
13198 {
13200 {
13203 strict_overflow_p);
13206 {
13212 strict_overflow_p));
13213 }
13218 strict_overflow_p);
13222 }
13225 }
13227 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13228 For floating point we further ensure that T is not denormal.
13229 Similar logic is present in nonzero_address in rtlanal.h.
13231 If the return value is based on the assumption that signed overflow
13232 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13233 change *STRICT_OVERFLOW_P. */
13235 bool
13237 tree type,
13238 tree op0,
13240 {
13243 {
13247 {
13248 /* With the presence of negative values it is hard
13249 to say something. */
13256 /* One of operands must be positive and the other non-negative. */
13257 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13258 overflows, on a twos-complement machine the sum of two
13259 nonnegative numbers can never be zero. */
13261 strict_overflow_p)
13263 strict_overflow_p));
13264 }
13269 {
13271 strict_overflow_p)
13273 strict_overflow_p))
13274 {
13277 }
13278 }
13287 {
13290 }
13297 {
13301 /* When both operands are nonzero, then MAX must be too. */
13303 strict_overflow_p))
13306 /* MAX where operand 0 is positive is positive. */
13308 strict_overflow_p);
13309 }
13310 /* MAX where operand 1 is positive is positive. */
13315 {
13319 }
13324 strict_overflow_p)
13326 strict_overflow_p));
13330 }
13333 }
13335 /* Return true when T is an address and is known to be nonzero.
13336 For floating point we further ensure that T is not denormal.
13337 Similar logic is present in nonzero_address in rtlanal.h.
13339 If the return value is based on the assumption that signed overflow
13340 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13341 change *STRICT_OVERFLOW_P. */
13343 bool
13345 {
13348 {
13353 {
13362 /* For objects in symbol table check if we know they are non-zero.
13363 Don't do anything for variables and functions before symtab is built;
13364 it is quite possible that they will be declared weak later. */
13366 {
13372 else
13374 }
13376 /* Function local objects are never NULL. */
13383 /* Constants are never weak. */
13388 }
13396 {
13400 }
13405 }
13407 }
13409 #define integer_valued_real_p(X) \
13412 #define RECURSE(X) \
13413 ((integer_valued_real_p) (X, depth + 1))
13415 /* Return true if the floating point result of (CODE OP0) has an
13416 integer value. We also allow +Inf, -Inf and NaN to be considered
13417 integer values.
13419 DEPTH is the current nesting depth of the query. */
13421 bool
13423 {
13425 {
13432 CASE_CONVERT:
13433 {
13440 }
13444 }
13446 }
13448 /* Return true if the floating point result of (CODE OP0 OP1) has an
13449 integer value. We also allow +Inf, -Inf and NaN to be considered
13450 integer values.
13452 DEPTH is the current nesting depth of the query. */
13454 bool
13456 {
13458 {
13468 }
13470 }
13472 /* Return true if the floating point result of calling FNDECL with arguments
13473 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13474 considered integer values. If FNDECL takes fewer than 2 arguments,
13475 the remaining ARGn are null.
13477 DEPTH is the current nesting depth of the query. */
13479 bool
13481 {
13483 {
13484 CASE_CFN_CEIL:
13485 CASE_CFN_FLOOR:
13486 CASE_CFN_NEARBYINT:
13487 CASE_CFN_RINT:
13488 CASE_CFN_ROUND:
13489 CASE_CFN_TRUNC:
13492 CASE_CFN_FMIN:
13493 CASE_CFN_FMAX:
13498 }
13500 }
13502 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13503 has an integer value. We also allow +Inf, -Inf and NaN to be
13504 considered integer values.
13506 DEPTH is the current nesting depth of the query. */
13508 bool
13510 {
13512 {
13520 /* Limit the depth of recursion to avoid quadratic behavior.
13521 This is expected to catch almost all occurrences in practice.
13522 If this code misses important cases that unbounded recursion
13523 would not, passes that need this information could be revised
13524 to provide it through dataflow propagation. */
13528 depth));
13532 }
13534 }
13536 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13537 has an integer value. We also allow +Inf, -Inf and NaN to be
13538 considered integer values.
13540 DEPTH is the current nesting depth of the query. */
13542 static bool
13544 {
13546 {
13557 }
13559 }
13561 #undef RECURSE
13562 #undef integer_valued_real_p
13564 /* Return true if the floating point expression T has an integer value.
13565 We also allow +Inf, -Inf and NaN to be considered integer values.
13567 DEPTH is the current nesting depth of the query. */
13569 bool
13571 {
13577 {
13593 }
13596 {
13602 {
13611 }
13615 }
13616 }
13618 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13619 attempt to fold the expression to a constant without modifying TYPE,
13620 OP0 or OP1.
13622 If the expression could be simplified to a constant, then return
13623 the constant. If the expression would not be simplified to a
13624 constant, then return NULL_TREE. */
13626 tree
13628 {
13631 }
13633 /* Given the components of a unary expression CODE, TYPE and OP0,
13634 attempt to fold the expression to a constant without modifying
13635 TYPE or OP0.
13637 If the expression could be simplified to a constant, then return
13638 the constant. If the expression would not be simplified to a
13639 constant, then return NULL_TREE. */
13641 tree
13643 {
13646 }
13648 /* If EXP represents referencing an element in a constant string
13649 (either via pointer arithmetic or array indexing), return the
13650 tree representing the value accessed, otherwise return NULL. */
13652 tree
13654 {
13658 {
13660 tree index;
13661 tree string;
13666 else
13667 {
13671 /* Optimize the special-case of a zero lower bound.
13673 We convert the low_bound to sizetype to avoid some problems
13674 with constant folding. (E.g. suppose the lower bound is 1,
13675 and its mode is QI. Without the conversion,l (ARRAY
13676 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13677 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13683 }
13696 }
13698 }
13700 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13701 an integer constant, real, or fixed-point constant.
13703 TYPE is the type of the result. */
13705 static tree
13707 {
13711 {
13713 {
13720 }
13727 {
13728 FIXED_VALUE_TYPE f;
13733 /* Propagate overflow flags. */
13737 }
13741 }
13744 }
13746 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13747 an integer constant or real constant.
13749 TYPE is the type of the result. */
13751 tree
13753 {
13757 {
13759 {
13760 /* If the value is unsigned or non-negative, then the absolute value
13761 is the same as the ordinary value. */
13765 /* If the value is negative, then the absolute value is
13766 its negation. */
13767 else
13768 {
13773 }
13774 }
13780 else
13786 }
13789 }
13791 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13792 constant. TYPE is the type of the result. */
13794 static tree
13796 {
13800 }
13802 /* Given CODE, a relational operator, the target type, TYPE and two
13803 constant operands OP0 and OP1, return the result of the
13804 relational operation. If the result is not a compile time
13805 constant, then return NULL_TREE. */
13807 static tree
13809 {
13812 /* From here on, the only cases we handle are when the result is
13813 known to be a constant. */
13816 {
13820 /* Handle the cases where either operand is a NaN. */
13822 {
13824 {
13852 }
13855 }
13858 }
13861 {
13865 }
13867 /* Handle equality/inequality of complex constants. */
13869 {
13880 else
13882 }
13885 {
13892 {
13904 }
13907 }
13909 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13911 To compute GT, swap the arguments and do LT.
13912 To compute GE, do LT and invert the result.
13913 To compute LE, swap the arguments, do LT and invert the result.
13914 To compute NE, do EQ and invert the result.
13916 Therefore, the code below must handle only EQ and LT. */
13919 {
13922 }
13924 /* Note that it is safe to invert for real values here because we
13925 have already handled the one case that it matters. */
13929 {
13932 }
13934 /* Compute a result for LT or EQ if args permit;
13935 Otherwise return T. */
13937 {
13940 else
13942 }
13943 else
13949 }
13951 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13952 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13953 itself. */
13955 tree
13957 {
13958 /* If the expression does not have side effects then we don't have to wrap
13959 it with a cleanup point expression. */
13963 /* If the expression is a return, check to see if the expression inside the
13964 return has no side effects or the right hand side of the modify expression
13965 inside the return. If either don't have side effects set we don't need to
13966 wrap the expression in a cleanup point expression. Note we don't check the
13967 left hand side of the modify because it should always be a return decl. */
13969 {
13976 }
13979 }
13981 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13982 of an indirection through OP0, or NULL_TREE if no simplification is
13983 possible. */
13985 tree
13987 {
13989 tree subtype;
13997 {
14000 /* *&CONST_DECL -> to the value of the const decl. */
14003 /* *&p => p; make sure to handle *&"str"[cst] here. */
14005 {
14009 else
14011 }
14012 /* *(foo *)&fooarray => fooarray[0] */
14015 && (!in_gimple_form
14017 {
14027 }
14028 /* *(foo *)&complexfoo => __real__ complexfoo */
14032 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14035 {
14039 }
14040 }
14044 {
14050 {
14051 tree op00type;
14055 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14058 {
14070 }
14071 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14074 {
14078 }
14079 /* ((foo *)&fooarray)[1] => fooarray[1] */
14082 {
14092 }
14093 }
14094 }
14096 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14099 && (!in_gimple_form
14101 {
14102 tree type_domain;
14112 NULL_TREE);
14113 }
14116 }
14118 /* Builds an expression for an indirection through T, simplifying some
14119 cases. */
14121 tree
14123 {
14131 }
14133 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14135 tree
14137 {
14142 else
14144 }
14146 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14147 whose result is ignored. The type of the returned tree need not be
14148 the same as the original expression. */
14150 tree
14152 {
14158 {
14169 else
14175 {
14191 }
14196 }
14197 }
14199 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14201 tree
14203 {
14209 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14210 have to do anything. Only do this when we are not given a const,
14211 because in that case, this check is more expensive than just
14212 doing it. */
14214 {
14219 }
14221 /* If divisor is a power of two, simplify this to bit manipulation. */
14223 {
14225 {
14239 }
14240 else
14241 {
14242 tree t;
14248 }
14249 }
14250 else
14251 {
14256 }
14259 }
14261 /* Likewise, but round down. */
14263 tree
14265 {
14272 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14273 have to do anything. Only do this when we are not given a const,
14274 because in that case, this check is more expensive than just
14275 doing it. */
14277 {
14282 }
14284 /* If divisor is a power of two, simplify this to bit manipulation. */
14286 {
14287 tree t;
14291 }
14292 else
14293 {
14298 }
14301 }
14303 /* Returns the pointer to the base of the object addressed by EXP and
14304 extracts the information about the offset of the access, storing it
14305 to PBITPOS and POFFSET. */
14307 static tree
14310 {
14311 tree core;
14312 machine_mode mode;
14314 HOST_WIDE_INT bitsize;
14318 {
14323 }
14324 else
14325 {
14329 }
14332 }
14334 /* Returns true if addresses of E1 and E2 differ by a constant, false
14335 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14337 bool
14339 {
14353 {
14363 }
14365 {
14366 /* If only one of the offsets is non-constant, the difference cannot
14367 be a constant. */
14369 }
14370 else
14375 }
14377 /* Return OFF converted to a pointer offset type suitable as offset for
14378 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14379 tree
14381 {
14383 }
14385 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14386 tree
14388 {
14391 }
14393 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14394 tree
14396 {
14399 }
14401 /* Return a char pointer for a C string if it is a string constant
14402 or sum of string constant and integer constant. */
14406 {
14407 tree offset_node;
14420 }