| blob | bff39c7b3a5901534cbe181a455b470a156fe41e |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2016 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. */
80 #ifndef LOAD_EXTEND_OP
81 #define LOAD_EXTEND_OP(M) UNKNOWN
82 #endif
84 /* Nonzero if we are folding constants inside an initializer; zero
85 otherwise. */
88 /* The following constants represent a bit based encoding of GCC's
89 comparison operators. This encoding simplifies transformations
90 on relational comparison operators, such as AND and OR. */
108 };
148 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
149 Otherwise, return LOC. */
151 static location_t
153 {
156 }
158 /* Similar to protected_set_expr_location, but never modify x in place,
159 if location can and needs to be set, unshare it. */
163 {
169 {
172 }
174 }
175 \f
176 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
177 division and returns the quotient. Otherwise returns
178 NULL_TREE. */
180 tree
182 {
183 widest_int quo;
190 }
191 \f
192 /* This is nonzero if we should defer warnings about undefined
193 overflow. This facility exists because these warnings are a
194 special case. The code to estimate loop iterations does not want
195 to issue any warnings, since it works with expressions which do not
196 occur in user code. Various bits of cleanup code call fold(), but
197 only use the result if it has certain characteristics (e.g., is a
198 constant); that code only wants to issue a warning if the result is
199 used. */
203 /* If a warning about undefined overflow is deferred, this is the
204 warning. Note that this may cause us to turn two warnings into
205 one, but that is fine since it is sufficient to only give one
206 warning per expression. */
210 /* If a warning about undefined overflow is deferred, this is the
211 level at which the warning should be emitted. */
215 /* Start deferring overflow warnings. We could use a stack here to
216 permit nested calls, but at present it is not necessary. */
218 void
220 {
222 }
224 /* Stop deferring overflow warnings. If there is a pending warning,
225 and ISSUE is true, then issue the warning if appropriate. STMT is
226 the statement with which the warning should be associated (used for
227 location information); STMT may be NULL. CODE is the level of the
228 warning--a warn_strict_overflow_code value. This function will use
229 the smaller of CODE and the deferred code when deciding whether to
230 issue the warning. CODE may be zero to mean to always use the
231 deferred code. */
233 void
235 {
237 location_t locus;
242 {
248 }
259 /* Use the smallest code level when deciding to issue the
260 warning. */
269 else
272 }
274 /* Stop deferring overflow warnings, ignoring any deferred
275 warnings. */
277 void
279 {
281 }
283 /* Whether we are deferring overflow warnings. */
285 bool
287 {
289 }
291 /* This is called when we fold something based on the fact that signed
292 overflow is undefined. */
294 static void
296 {
298 {
301 {
304 }
305 }
308 }
309 \f
310 /* Return true if the built-in mathematical function specified by CODE
311 is odd, i.e. -f(x) == f(-x). */
313 bool
315 {
317 {
318 CASE_CFN_ASIN:
319 CASE_CFN_ASINH:
320 CASE_CFN_ATAN:
321 CASE_CFN_ATANH:
322 CASE_CFN_CASIN:
323 CASE_CFN_CASINH:
324 CASE_CFN_CATAN:
325 CASE_CFN_CATANH:
326 CASE_CFN_CBRT:
327 CASE_CFN_CPROJ:
328 CASE_CFN_CSIN:
329 CASE_CFN_CSINH:
330 CASE_CFN_CTAN:
331 CASE_CFN_CTANH:
332 CASE_CFN_ERF:
333 CASE_CFN_LLROUND:
334 CASE_CFN_LROUND:
335 CASE_CFN_ROUND:
336 CASE_CFN_SIN:
337 CASE_CFN_SINH:
338 CASE_CFN_TAN:
339 CASE_CFN_TANH:
340 CASE_CFN_TRUNC:
343 CASE_CFN_LLRINT:
344 CASE_CFN_LRINT:
345 CASE_CFN_NEARBYINT:
346 CASE_CFN_RINT:
351 }
353 }
355 /* Check whether we may negate an integer constant T without causing
356 overflow. */
358 bool
360 {
361 tree type;
370 }
372 /* Determine whether an expression T can be cheaply negated using
373 the function negate_expr without introducing undefined overflow. */
375 static bool
377 {
378 tree type;
387 {
392 /* Check that -CST will not overflow type. */
405 /* We want to canonicalize to positive real constants. Pretend
406 that only negative ones can be easily negated. */
414 {
425 }
440 /* -(A + B) -> (-B) - A. */
445 /* -(A + B) -> (-A) - B. */
449 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
460 /* INT_MIN/n * n doesn't overflow while negating one operand it does
461 if n is a (negative) power of two. */
470 /* Fall through. */
485 /* In general we can't negate B in A / B, because if A is INT_MIN and
486 B is 1, we may turn this into INT_MIN / -1 which is undefined
487 and actually traps on some architectures. */
496 /* Negate -((double)float) as (double)(-float). */
498 {
502 }
506 /* Negate -f(x) as f(-x). */
512 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
514 {
518 }
523 }
525 }
527 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
528 simplification is possible.
529 If negate_expr_p would return true for T, NULL_TREE will never be
530 returned. */
532 static tree
534 {
536 tree tem;
539 {
540 /* Convert - (~A) to A + 1. */
566 {
571 }
575 {
580 {
584 }
587 }
610 {
611 /* -(A + B) -> (-B) - A. */
615 {
619 }
621 /* -(A + B) -> (-A) - B. */
623 {
627 }
628 }
632 /* - (A - B) -> B - A */
644 /* Fall through. */
648 {
657 }
669 /* In general we can't negate B in A / B, because if A is INT_MIN and
670 B is 1, we may turn this into INT_MIN / -1 which is undefined
671 and actually traps on some architectures. */
683 /* Convert -((double)float) into (double)(-float). */
685 {
689 }
693 /* Negate -f(x) as f(-x). */
696 {
702 }
706 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
708 {
711 {
718 }
719 }
724 }
727 }
729 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
730 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
731 return NULL_TREE. */
733 static tree
735 {
737 location_t loc;
750 }
751 \f
752 /* Split a tree IN into a constant, literal and variable parts that could be
753 combined with CODE to make IN. "constant" means an expression with
754 TREE_CONSTANT but that isn't an actual constant. CODE must be a
755 commutative arithmetic operation. Store the constant part into *CONP,
756 the literal in *LITP and return the variable part. If a part isn't
757 present, set it to null. If the tree does not decompose in this way,
758 return the entire tree as the variable part and the other parts as null.
760 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
761 case, we negate an operand that was subtracted. Except if it is a
762 literal for which we use *MINUS_LITP instead.
764 If NEGATE_P is true, we are negating all of IN, again except a literal
765 for which we use *MINUS_LITP instead. If a variable part is of pointer
766 type, it is negated after converting to TYPE. This prevents us from
767 generating illegal MINUS pointer expression. LOC is the location of
768 the converted variable part.
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. */
834 {
835 /* Convert to TYPE before negating. */
838 }
839 }
844 {
845 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
846 when IN is constant. */
849 }
850 else
854 {
861 {
862 /* Convert to TYPE before negating. */
865 }
866 }
869 }
871 /* Re-associate trees split by the above function. T1 and T2 are
872 either expressions to associate or null. Return the new
873 expression, if any. LOC is the location of the new expression. If
874 we build an operation, do it in TYPE and with CODE. */
876 static tree
878 {
884 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
885 try to fold this since we will have infinite recursion. But do
886 deal with any NEGATE_EXPRs. */
889 {
891 {
904 }
906 {
909 }
913 }
917 }
918 \f
919 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
920 for use in int_const_binop, size_binop and size_diffop. */
922 static bool
924 {
931 {
940 }
945 }
948 /* Combine two integer constants ARG1 and ARG2 under operation CODE
949 to produce a new constant. Return NULL_TREE if we don't know how
950 to evaluate CODE at compile-time. */
952 static tree
955 {
956 wide_int res;
957 tree t;
966 {
982 {
986 else
988 }
991 /* It's unclear from the C standard whether shifts can overflow.
992 The following code ignores overflow; perhaps a C standard
993 interpretation ruling is needed. */
995 else
1002 {
1006 else
1008 }
1012 else
1091 }
1099 }
1101 tree
1103 {
1105 }
1107 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1108 constant. We assume ARG1 and ARG2 have the same data type, or at least
1109 are the same kind of constant and the same machine mode. Return zero if
1110 combining the constants is not allowed in the current operating mode. */
1112 static tree
1114 {
1115 /* Sanity check for the recursive cases. */
1123 {
1129 }
1132 {
1133 machine_mode mode;
1134 REAL_VALUE_TYPE d1;
1135 REAL_VALUE_TYPE d2;
1136 REAL_VALUE_TYPE value;
1137 REAL_VALUE_TYPE result;
1141 /* The following codes are handled by real_arithmetic. */
1143 {
1154 }
1162 /* Don't perform operation if we honor signaling NaNs and
1163 either operand is a signaling NaN. */
1169 /* Don't perform operation if it would raise a division
1170 by zero exception. */
1176 /* If either operand is a NaN, just return it. Otherwise, set up
1177 for floating-point trap; we return an overflow. */
1179 {
1180 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1181 is off. */
1185 }
1187 {
1188 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1189 is off. */
1193 }
1198 /* Don't constant fold this floating point operation if
1199 the result has overflowed and flag_trapping_math. */
1207 /* Don't constant fold this floating point operation if the
1208 result may dependent upon the run-time rounding mode and
1209 flag_rounding_math is set, or if GCC's software emulation
1210 is unable to accurately represent the result. */
1220 }
1223 {
1224 FIXED_VALUE_TYPE f1;
1225 FIXED_VALUE_TYPE f2;
1226 FIXED_VALUE_TYPE result;
1231 /* The following codes are handled by fixed_arithmetic. */
1233 {
1245 {
1252 }
1257 }
1264 /* Propagate overflow flags. */
1268 }
1271 {
1280 {
1291 mpc_mul);
1305 mpc_div);
1306 /* Fallthru ... */
1312 {
1313 /* Keep this algorithm in sync with
1314 tree-complex.c:expand_complex_div_straight().
1316 Expand complex division to scalars, straightforward algorithm.
1317 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1318 t = br*br + bi*bi
1319 */
1320 tree magsquared
1324 tree t1
1328 tree t2
1335 }
1336 else
1337 {
1338 /* Keep this algorithm in sync with
1339 tree-complex.c:expand_complex_div_wide().
1341 Expand complex division to scalars, modified algorithm to minimize
1342 overflow with wide input ranges. */
1348 {
1349 /* In the TRUE branch, we compute
1350 ratio = br/bi;
1351 div = (br * ratio) + bi;
1352 tr = (ar * ratio) + ai;
1353 ti = (ai * ratio) - ar;
1354 tr = tr / div;
1355 ti = ti / div; */
1366 }
1367 else
1368 {
1369 /* In the FALSE branch, we compute
1370 ratio = d/c;
1371 divisor = (d * ratio) + c;
1372 tr = (b * ratio) + a;
1373 ti = b - (a * ratio);
1374 tr = tr / div;
1375 ti = ti / div; */
1387 }
1388 }
1393 }
1397 }
1401 {
1407 {
1413 /* It is possible that const_binop cannot handle the given
1414 code and return NULL_TREE */
1417 }
1420 }
1422 /* Shifts allow a scalar offset for a vector. */
1425 {
1431 {
1436 /* It is possible that const_binop cannot handle the given
1437 code and return NULL_TREE. */
1440 }
1443 }
1445 }
1447 /* Overload that adds a TYPE parameter to be able to dispatch
1448 to fold_relational_const. */
1450 tree
1452 {
1456 /* ??? Until we make the const_binop worker take the type of the
1457 result as argument put those cases that need it here. */
1459 {
1470 {
1486 {
1492 }
1495 }
1501 {
1526 {
1539 }
1542 }
1545 }
1550 /* Make sure type and arg0 have the same saturating flag. */
1555 }
1557 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1558 Return zero if computing the constants is not possible. */
1560 tree
1562 {
1563 /* Don't perform the operation, other than NEGATE and ABS, if
1564 flag_signaling_nans is on and the operand is a signaling NaN. */
1573 {
1574 CASE_CONVERT:
1581 /* If the source address is 0, and the source address space
1582 cannot have a valid object at 0, fold to dest type null. */
1593 {
1594 /* Can't call fold_negate_const directly here as that doesn't
1595 handle all cases and we might not be able to negate some
1596 constants. */
1601 }
1610 {
1614 }
1620 /* Perform BIT_NOT_EXPR on each element individually. */
1622 {
1624 tree elem;
1629 {
1635 }
1638 }
1660 {
1679 else
1683 {
1687 }
1690 }
1695 {
1709 {
1714 }
1717 {
1721 }
1724 }
1728 }
1731 }
1733 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1734 indicates which particular sizetype to create. */
1736 tree
1738 {
1740 }
1741 \f
1742 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1743 is a tree code. The type of the result is taken from the operands.
1744 Both must be equivalent integer types, ala int_binop_types_match_p.
1745 If the operands are constant, so is the result. */
1747 tree
1749 {
1758 /* Handle the special case of two integer constants faster. */
1760 {
1761 /* And some specific cases even faster than that. */
1763 {
1768 }
1770 {
1773 }
1775 {
1778 }
1780 /* Handle general case of two integer constants. For sizetype
1781 constant calculations we always want to know about overflow,
1782 even in the unsigned case. */
1784 }
1787 }
1789 /* Given two values, either both of sizetype or both of bitsizetype,
1790 compute the difference between the two values. Return the value
1791 in signed type corresponding to the type of the operands. */
1793 tree
1795 {
1797 tree ctype;
1802 /* If the type is already signed, just do the simple thing. */
1810 else
1813 /* If either operand is not a constant, do the conversions to the signed
1814 type and subtract. The hardware will do the right thing with any
1815 overflow in the subtraction. */
1821 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1822 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1823 overflow) and negate (which can't either). Special-case a result
1824 of zero while we're here. */
1830 else
1834 MINUS_EXPR,
1836 }
1837 \f
1838 /* A subroutine of fold_convert_const handling conversions of an
1839 INTEGER_CST to another integer type. */
1841 static tree
1843 {
1844 /* Given an integer constant, make new constant with new type,
1845 appropriately sign-extended or truncated. Use widest_int
1846 so that any extension is done according ARG1's type. */
1850 }
1852 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1853 to an integer type. */
1855 static tree
1857 {
1859 tree t;
1861 /* The following code implements the floating point to integer
1862 conversion rules required by the Java Language Specification,
1863 that IEEE NaNs are mapped to zero and values that overflow
1864 the target precision saturate, i.e. values greater than
1865 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1866 are mapped to INT_MIN. These semantics are allowed by the
1867 C and C++ standards that simply state that the behavior of
1868 FP-to-integer conversion is unspecified upon overflow. */
1870 wide_int val;
1871 REAL_VALUE_TYPE r;
1875 {
1882 }
1884 /* If R is NaN, return zero and show we have an overflow. */
1886 {
1889 }
1891 /* See if R is less than the lower bound or greater than the
1892 upper bound. */
1895 {
1899 {
1902 }
1903 }
1906 {
1909 {
1912 {
1915 }
1916 }
1917 }
1924 }
1926 /* A subroutine of fold_convert_const handling conversions of a
1927 FIXED_CST to an integer type. */
1929 static tree
1931 {
1932 tree t;
1936 /* Right shift FIXED_CST to temp by fbit. */
1940 {
1942 HOST_BITS_PER_DOUBLE_INT,
1945 /* Left shift temp to temp_trunc by fbit. */
1947 HOST_BITS_PER_DOUBLE_INT,
1949 }
1950 else
1951 {
1954 }
1956 /* If FIXED_CST is negative, we need to round the value toward 0.
1957 By checking if the fractional bits are not zero to add 1 to temp. */
1963 /* Given a fixed-point constant, make new constant with new type,
1964 appropriately sign-extended or truncated. */
1972 }
1974 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1975 to another floating point type. */
1977 static tree
1979 {
1980 REAL_VALUE_TYPE value;
1981 tree t;
1983 /* Don't perform the operation if flag_signaling_nans is on
1984 and the operand is a signaling NaN. */
1992 /* If converting an infinity or NAN to a representation that doesn't
1993 have one, set the overflow bit so that we can produce some kind of
1994 error message at the appropriate point if necessary. It's not the
1995 most user-friendly message, but it's better than nothing. */
2002 /* Regular overflow, conversion produced an infinity in a mode that
2003 can't represent them. */
2008 else
2011 }
2013 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2014 to a floating point type. */
2016 static tree
2018 {
2019 REAL_VALUE_TYPE value;
2020 tree t;
2027 }
2029 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2030 to another fixed-point type. */
2032 static tree
2034 {
2035 FIXED_VALUE_TYPE value;
2036 tree t;
2043 /* Propagate overflow flags. */
2047 }
2049 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2050 to a fixed-point type. */
2052 static tree
2054 {
2055 FIXED_VALUE_TYPE value;
2056 tree t;
2058 double_int di;
2065 else
2073 /* Propagate overflow flags. */
2077 }
2079 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2080 to a fixed-point type. */
2082 static tree
2084 {
2085 FIXED_VALUE_TYPE value;
2086 tree t;
2094 /* Propagate overflow flags. */
2098 }
2100 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2101 type TYPE. If no simplification can be done return NULL_TREE. */
2103 static tree
2105 {
2111 {
2118 }
2120 {
2127 }
2129 {
2136 }
2138 {
2141 {
2146 {
2152 }
2154 }
2155 }
2157 }
2159 /* Construct a vector of zero elements of vector type TYPE. */
2161 static tree
2163 {
2164 tree t;
2168 }
2170 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2172 bool
2174 {
2189 {
2204 }
2205 }
2207 /* Convert expression ARG to type TYPE. Used by the middle-end for
2208 simple conversions in preference to calling the front-end's convert. */
2210 tree
2212 {
2214 tree tem;
2225 {
2228 /* Handle conversions between pointers to different address spaces. */
2233 /* fall through */
2238 {
2242 }
2256 {
2260 }
2262 {
2266 }
2268 {
2272 }
2275 {
2293 }
2298 {
2302 }
2305 {
2319 }
2323 {
2332 integer_zero_node));
2334 {
2338 {
2344 }
2352 }
2356 }
2374 }
2375 fold_convert_exit:
2378 }
2379 \f
2380 /* Return false if expr can be assumed not to be an lvalue, true
2381 otherwise. */
2383 static bool
2385 {
2386 /* We only need to wrap lvalue tree codes. */
2388 {
2419 /* Assume the worst for front-end tree codes. */
2423 }
2426 }
2428 /* Return an expr equal to X but certainly not valid as an lvalue. */
2430 tree
2432 {
2433 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2434 us. */
2441 }
2443 /* When pedantic, return an expr equal to X but certainly not valid as a
2444 pedantic lvalue. Otherwise, return X. */
2446 static tree
2448 {
2450 }
2451 \f
2452 /* Given a tree comparison code, return the code that is the logical inverse.
2453 It is generally not safe to do this for floating-point comparisons, except
2454 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2455 ERROR_MARK in this case. */
2457 enum tree_code
2459 {
2465 {
2496 }
2497 }
2499 /* Similar, but return the comparison that results if the operands are
2500 swapped. This is safe for floating-point. */
2502 enum tree_code
2504 {
2506 {
2532 }
2533 }
2536 /* Convert a comparison tree code from an enum tree_code representation
2537 into a compcode bit-based encoding. This function is the inverse of
2538 compcode_to_comparison. */
2540 static enum comparison_code
2542 {
2544 {
2575 }
2576 }
2578 /* Convert a compcode bit-based encoding of a comparison operator back
2579 to GCC's enum tree_code representation. This function is the
2580 inverse of comparison_to_compcode. */
2582 static enum tree_code
2584 {
2586 {
2617 }
2618 }
2620 /* Return a tree for the comparison which is the combination of
2621 doing the AND or OR (depending on CODE) of the two operations LCODE
2622 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2623 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2624 if this makes the transformation invalid. */
2626 tree
2631 {
2638 {
2649 }
2652 {
2653 /* Eliminate unordered comparisons, as well as LTGT and ORD
2654 which are not used unless the mode has NaNs. */
2660 }
2662 {
2663 /* Check that the original operation and the optimized ones will trap
2664 under the same condition. */
2675 /* In a short-circuited boolean expression the LHS might be
2676 such that the RHS, if evaluated, will never trap. For
2677 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2678 if neither x nor y is NaN. (This is a mixed blessing: for
2679 example, the expression above will never trap, hence
2680 optimizing it to x < y would be invalid). */
2685 /* If the comparison was short-circuited, and only the RHS
2686 trapped, we may now generate a spurious trap. */
2691 /* If we changed the conditions that cause a trap, we lose. */
2694 }
2700 else
2701 {
2706 }
2707 }
2708 \f
2709 /* Return nonzero if two operands (typically of the same tree node)
2710 are necessarily equal. FLAGS modifies behavior as follows:
2712 If OEP_ONLY_CONST is set, only return nonzero for constants.
2713 This function tests whether the operands are indistinguishable;
2714 it does not test whether they are equal using C's == operation.
2715 The distinction is important for IEEE floating point, because
2716 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2717 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2719 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2720 even though it may hold multiple values during a function.
2721 This is because a GCC tree node guarantees that nothing else is
2722 executed between the evaluation of its "operands" (which may often
2723 be evaluated in arbitrary order). Hence if the operands themselves
2724 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2725 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2726 unset means assuming isochronic (or instantaneous) tree equivalence.
2727 Unless comparing arbitrary expression trees, such as from different
2728 statements, this flag can usually be left unset.
2730 If OEP_PURE_SAME is set, then pure functions with identical arguments
2731 are considered the same. It is used when the caller has other ways
2732 to ensure that global memory is unchanged in between.
2734 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2735 not values of expressions.
2737 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2738 any operand with side effect. This is unnecesarily conservative in the
2739 case we know that arg0 and arg1 are in disjoint code paths (such as in
2740 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2741 addresses with TREE_CONSTANT flag set so we know that &var == &var
2742 even if var is volatile. */
2744 int
2746 {
2747 /* If either is ERROR_MARK, they aren't equal. */
2753 /* Similar, if either does not have a type (like a released SSA name),
2754 they aren't equal. */
2758 /* We cannot consider pointers to different address space equal. */
2765 /* Check equality of integer constants before bailing out due to
2766 precision differences. */
2768 {
2769 /* Address of INTEGER_CST is not defined; check that we did not forget
2770 to drop the OEP_ADDRESS_OF flags. */
2773 }
2776 {
2777 /* If both types don't have the same signedness, then we can't consider
2778 them equal. We must check this before the STRIP_NOPS calls
2779 because they may change the signedness of the arguments. As pointers
2780 strictly don't have a signedness, require either two pointers or
2781 two non-pointers as well. */
2787 /* If both types don't have the same precision, then it is not safe
2788 to strip NOPs. */
2795 }
2796 #if 0
2797 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2798 sanity check once the issue is solved. */
2799 else
2800 /* Addresses of conversions and SSA_NAMEs (and many other things)
2801 are not defined. Check that we did not forget to drop the
2802 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2805 #endif
2807 /* In case both args are comparisons but with different comparison
2808 code, try to swap the comparison operands of one arg to produce
2809 a match and compare that variant. */
2813 {
2821 }
2824 {
2825 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2827 ;
2829 {
2830 /* If we are interested in comparing addresses ignore
2831 MEM_REF wrappings of the base that can appear just for
2832 TBAA reasons. */
2846 }
2847 else
2849 }
2851 /* When not checking adddresses, this is needed for conversions and for
2852 COMPONENT_REF. Might as well play it safe and always test this. */
2859 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2860 We don't care about side effects in that case because the SAVE_EXPR
2861 takes care of that for us. In all other cases, two expressions are
2862 equal if they have no side effects. If we have two identical
2863 expressions with side effects that should be treated the same due
2864 to the only side effects being identical SAVE_EXPR's, that will
2865 be detected in the recursive calls below.
2866 If we are taking an invariant address of two identical objects
2867 they are necessarily equal as well. */
2874 /* Next handle constant cases, those for which we can return 1 even
2875 if ONLY_CONST is set. */
2878 {
2892 {
2893 /* If we do not distinguish between signed and unsigned zero,
2894 consider them equal. */
2897 }
2901 {
2908 {
2912 }
2914 }
2918 flags)
2920 flags));
2931 flags | OEP_ADDRESS_OF
2934 /* In GIMPLE empty constructors are allowed in initializers of
2935 aggregates. */
2940 }
2945 /* Define macros to test an operand from arg0 and arg1 for equality and a
2946 variant that allows null and views null as being different from any
2947 non-null value. In the latter case, if either is null, the both
2948 must be; otherwise, do the normal comparison. */
2949 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2950 TREE_OPERAND (arg1, N), flags)
2952 #define OP_SAME_WITH_NULL(N) \
2953 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2954 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2957 {
2959 /* Two conversions are equal only if signedness and modes match. */
2961 {
2962 CASE_CONVERT:
2970 }
2980 /* For commutative ops, allow the other order. */
2988 /* If either of the pointer (or reference) expressions we are
2989 dereferencing contain a side effect, these cannot be equal,
2990 but their addresses can be. */
2997 {
3007 /* Require the same offset. */
3013 /* Fallthru. */
3021 {
3022 /* Require equal access sizes */
3028 flags)))
3030 /* Verify that access happens in similar types. */
3033 /* Verify that accesses are TBAA compatible. */
3042 /* Verify that alignment is compatible. */
3046 }
3049 /* TARGET_MEM_REF require equal extra operands. */
3060 /* Compare the array index by value if it is constant first as we
3061 may have different types but same value here. */
3067 /* Compare low bound and element size as with OEP_ADDRESS_OF
3068 we have to account for the offset of the ref. */
3073 array_ref_low_bound
3077 array_ref_element_size
3079 flags))));
3082 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3083 may be NULL when we're called to compare MEM_EXPRs. */
3098 }
3102 {
3104 /* Be sure we pass right ADDRESS_OF flag. */
3122 /* The multiplcation operands are commutative. */
3123 /* FALLTHRU */
3131 /* Otherwise take into account this is a commutative operation. */
3149 }
3153 {
3157 /* If not both CALL_EXPRs are either internal or normal function
3158 functions, then they are not equal. */
3161 {
3162 /* If the CALL_EXPRs call different internal functions, then they
3163 are not equal. */
3166 }
3167 else
3168 {
3169 /* If the CALL_EXPRs call different functions, then they are not
3170 equal. */
3172 flags))
3174 }
3176 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3177 {
3181 else
3185 }
3187 /* Now see if all the arguments are the same. */
3188 {
3199 /* If we get here and both argument lists are exhausted
3200 then the CALL_EXPRs are equal. */
3202 }
3205 }
3208 /* Consider __builtin_sqrt equal to sqrt. */
3216 {
3217 /* In GIMPLE constructors are used only to build vectors from
3218 elements. Individual elements in the constructor must be
3219 indexed in increasing order and form an initial sequence.
3221 We make no effort to compare constructors in generic.
3222 (see sem_variable::equals in ipa-icf which can do so for
3223 constants). */
3228 /* Be sure that vectors constructed have the same representation.
3229 We only tested element precision and modes to match.
3230 Vectors may be BLKmode and thus also check that the number of
3231 parts match. */
3244 {
3249 /* In GIMPLE the indexes can be either NULL or matching i.
3250 Double check this so we won't get false
3251 positives for GENERIC. */
3259 }
3261 }
3266 }
3268 #undef OP_SAME
3269 #undef OP_SAME_WITH_NULL
3270 }
3271 \f
3272 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3273 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3275 When in doubt, return 0. */
3277 static int
3279 {
3291 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3292 and see if the inner values are the same. This removes any
3293 signedness comparison, which doesn't matter here. */
3300 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3301 actual comparison operand, ARG0.
3303 First throw away any conversions to wider types
3304 already present in the operands. */
3313 {
3316 /* Make sure shorter operand is extended the right way
3317 to match the longer operand. */
3323 }
3326 }
3327 \f
3328 /* See if ARG is an expression that is either a comparison or is performing
3329 arithmetic on comparisons. The comparisons must only be comparing
3330 two different values, which will be stored in *CVAL1 and *CVAL2; if
3331 they are nonzero it means that some operands have already been found.
3332 No variables may be used anywhere else in the expression except in the
3333 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3334 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3336 If this is true, return 1. Otherwise, return zero. */
3338 static int
3340 {
3344 /* We can handle some of the tcc_expression cases here. */
3354 {
3355 /* If we've already found a CVAL1 or CVAL2, this expression is
3356 two complex to handle. */
3362 }
3365 {
3388 /* First see if we can handle the first operand, then the second. For
3389 the second operand, we know *CVAL1 can't be zero. It must be that
3390 one side of the comparison is each of the values; test for the
3391 case where this isn't true by failing if the two operands
3392 are the same. */
3401 ;
3405 ;
3406 else
3410 ;
3414 ;
3415 else
3422 }
3423 }
3424 \f
3425 /* ARG is a tree that is known to contain just arithmetic operations and
3426 comparisons. Evaluate the operations in the tree substituting NEW0 for
3427 any occurrence of OLD0 as an operand of a comparison and likewise for
3428 NEW1 and OLD1. */
3430 static tree
3433 {
3438 /* We can handle some of the tcc_expression cases here. */
3446 {
3461 {
3480 }
3481 /* Fall through - ??? */
3484 {
3488 /* We need to check both for exact equality and tree equality. The
3489 former will be true if the operand has a side-effect. In that
3490 case, we know the operand occurred exactly once. */
3503 }
3507 }
3508 }
3509 \f
3510 /* Return a tree for the case when the result of an expression is RESULT
3511 converted to TYPE and OMITTED was previously an operand of the expression
3512 but is now not needed (e.g., we folded OMITTED * 0).
3514 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3515 the conversion of RESULT to TYPE. */
3517 tree
3519 {
3522 /* If the resulting operand is an empty statement, just return the omitted
3523 statement casted to void. */
3533 }
3535 /* Return a tree for the case when the result of an expression is RESULT
3536 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3537 of the expression but are now not needed.
3539 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3540 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3541 evaluated before OMITTED2. Otherwise, if neither has side effects,
3542 just do the conversion of RESULT to TYPE. */
3544 tree
3547 {
3556 }
3558 \f
3559 /* Return a simplified tree node for the truth-negation of ARG. This
3560 never alters ARG itself. We assume that ARG is an operation that
3561 returns a truth value (0 or 1).
3563 FIXME: one would think we would fold the result, but it causes
3564 problems with the dominator optimizer. */
3566 static tree
3568 {
3573 /* If this is a comparison, we can simply invert it, except for
3574 floating-point non-equality comparisons, in which case we just
3575 enclose a TRUTH_NOT_EXPR around what we have. */
3578 {
3581 && flag_trapping_math
3595 }
3598 {
3617 /* Here we can invert either operand. We invert the first operand
3618 unless the second operand is a TRUTH_NOT_EXPR in which case our
3619 result is the XOR of the first operand with the inside of the
3620 negation of the second operand. */
3625 else
3648 {
3655 /* A COND_EXPR may have a throw as one operand, which
3656 then has void type. Just leave void operands
3657 as they are. */
3663 }
3675 CASE_CONVERT:
3679 /* ... fall through ... */
3701 }
3702 }
3704 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3705 assume that ARG is an operation that returns a truth value (0 or 1
3706 for scalars, 0 or -1 for vectors). Return the folded expression if
3707 folding is successful. Otherwise, return NULL_TREE. */
3709 static tree
3711 {
3714 ? BIT_NOT_EXPR
3717 }
3719 /* Return a simplified tree node for the truth-negation of ARG. This
3720 never alters ARG itself. We assume that ARG is an operation that
3721 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3723 tree
3725 {
3731 ? BIT_NOT_EXPR
3734 }
3736 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3737 with code CODE. This optimization is unsafe. */
3738 static tree
3741 {
3745 /* (A / C) +- (B / C) -> (A +- B) / C. */
3755 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3760 {
3772 }
3775 }
3776 \f
3777 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3778 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3779 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3780 is the original memory reference used to preserve the alias set of
3781 the access. */
3783 static tree
3787 {
3797 {
3804 }
3819 }
3821 /* Optimize a bit-field compare.
3823 There are two cases: First is a compare against a constant and the
3824 second is a comparison of two items where the fields are at the same
3825 bit position relative to the start of a chunk (byte, halfword, word)
3826 large enough to contain it. In these cases we can avoid the shift
3827 implicit in bitfield extractions.
3829 For constants, we emit a compare of the shifted constant with the
3830 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3831 compared. For two fields at the same position, we do the ANDs with the
3832 similar mask and compare the result of the ANDs.
3834 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3835 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3836 are the left and right operands of the comparison, respectively.
3838 If the optimization described above can be done, we return the resulting
3839 tree. Otherwise we return zero. */
3841 static tree
3844 {
3847 tree unsigned_type;
3854 tree mask;
3855 tree offset;
3857 /* Get all the information about the extractions being done. If the bit size
3858 if the same as the size of the underlying object, we aren't doing an
3859 extraction at all and so can do nothing. We also don't want to
3860 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3861 then will no longer be able to replace it. */
3870 else
3871 {
3872 /* If this is not a constant, we can only do something if bit positions,
3873 sizes, signedness and storage order are the same. */
3874 rinner
3882 }
3884 /* See if we can find a mode to refer to this field. We should be able to,
3885 but fail if we can't. */
3894 /* Set signed and unsigned types of the precision of this mode for the
3895 shifts below. */
3898 /* Compute the bit position and size for the new reference and our offset
3899 within it. If the new reference is the same size as the original, we
3900 won't optimize anything, so return zero. */
3910 /* Make the mask to be used against the extracted field. */
3917 /* If not comparing with constant, just rework the comparison
3918 and return. */
3922 unsigned_type,
3925 mask),
3928 unsigned_type,
3931 mask));
3933 /* Otherwise, we are handling the constant case. See if the constant is too
3934 big for the field. Warn and return a tree for 0 (false) if so. We do
3935 this not only for its own sake, but to avoid having to test for this
3936 error case below. If we didn't, we might generate wrong code.
3938 For unsigned fields, the constant shifted right by the field length should
3939 be all zero. For signed fields, the high-order bits should agree with
3940 the sign bit. */
3943 {
3945 {
3949 }
3950 }
3951 else
3952 {
3955 {
3959 }
3960 }
3962 /* Single-bit compares should always be against zero. */
3964 {
3967 }
3969 /* Make a new bitfield reference, shift the constant over the
3970 appropriate number of bits and mask it with the computed mask
3971 (in case this was a signed field). If we changed it, make a new one. */
3979 mask);
3984 }
3985 \f
3986 /* Subroutine for fold_truth_andor_1: decode a field reference.
3988 If EXP is a comparison reference, we return the innermost reference.
3990 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3991 set to the starting bit number.
3993 If the innermost field can be completely contained in a mode-sized
3994 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3996 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3997 otherwise it is not changed.
3999 *PUNSIGNEDP is set to the signedness of the field.
4001 *PREVERSEP is set to the storage order of the field.
4003 *PMASK is set to the mask used. This is either contained in a
4004 BIT_AND_EXPR or derived from the width of the field.
4006 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4008 Return 0 if this is not a component reference or is one that we can't
4009 do anything with. */
4011 static tree
4016 {
4021 tree unsigned_type;
4024 /* All the optimizations using this function assume integer fields.
4025 There are problems with FP fields since the type_for_size call
4026 below can fail for, e.g., XFmode. */
4030 /* We are interested in the bare arrangement of bits, so strip everything
4031 that doesn't affect the machine mode. However, record the type of the
4032 outermost expression if it may matter below. */
4039 {
4045 }
4056 /* If the number of bits in the reference is the same as the bitsize of
4057 the outer type, then the outer type gives the signedness. Otherwise
4058 (in case of a small bitfield) the signedness is unchanged. */
4062 /* Compute the mask to access the bitfield. */
4071 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4079 }
4081 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4082 bit positions and MASK is SIGNED. */
4084 static int
4086 {
4090 /* If this function returns true when the type of the mask is
4091 UNSIGNED, then there will be errors. In particular see
4092 gcc.c-torture/execute/990326-1.c. There does not appear to be
4093 any documentation paper trail as to why this is so. But the pre
4094 wide-int worked with that restriction and it has been preserved
4095 here. */
4100 }
4102 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4103 represents the sign bit of EXP's type. If EXP represents a sign
4104 or zero extension, also test VAL against the unextended type.
4105 The return value is the (sub)expression whose sign bit is VAL,
4106 or NULL_TREE otherwise. */
4108 tree
4110 {
4112 tree t;
4114 /* Tree EXP must have an integral type. */
4119 /* Tree VAL must be an integer constant. */
4128 /* Handle extension from a narrower type. */
4134 }
4136 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4137 to be evaluated unconditionally. */
4139 static int
4141 {
4142 /* Strip any conversions that don't change the machine mode. */
4151 /* Don't regard global variables as simple. They may be
4152 allocated in ways unknown to the compiler (shared memory,
4153 #pragma weak, etc). */
4156 /* Weakrefs are not safe to be read, since they can be NULL.
4157 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4158 have DECL_WEAK flag set. */
4160 /* Loading a static variable is unduly expensive, but global
4161 registers aren't expensive. */
4163 }
4165 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4166 to be evaluated unconditionally.
4167 I addition to simple_operand_p, we assume that comparisons, conversions,
4168 and logic-not operations are simple, if their operands are simple, too. */
4170 static bool
4172 {
4192 }
4194 \f
4195 /* The following functions are subroutines to fold_range_test and allow it to
4196 try to change a logical combination of comparisons into a range test.
4198 For example, both
4199 X == 2 || X == 3 || X == 4 || X == 5
4200 and
4201 X >= 2 && X <= 5
4202 are converted to
4203 (unsigned) (X - 2) <= 3
4205 We describe each set of comparisons as being either inside or outside
4206 a range, using a variable named like IN_P, and then describe the
4207 range with a lower and upper bound. If one of the bounds is omitted,
4208 it represents either the highest or lowest value of the type.
4210 In the comments below, we represent a range by two numbers in brackets
4211 preceded by a "+" to designate being inside that range, or a "-" to
4212 designate being outside that range, so the condition can be inverted by
4213 flipping the prefix. An omitted bound is represented by a "-". For
4214 example, "- [-, 10]" means being outside the range starting at the lowest
4215 possible value and ending at 10, in other words, being greater than 10.
4216 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4217 always false.
4219 We set up things so that the missing bounds are handled in a consistent
4220 manner so neither a missing bound nor "true" and "false" need to be
4221 handled using a special case. */
4223 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4224 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4225 and UPPER1_P are nonzero if the respective argument is an upper bound
4226 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4227 must be specified for a comparison. ARG1 will be converted to ARG0's
4228 type if both are specified. */
4230 static tree
4233 {
4234 tree tem;
4238 /* If neither arg represents infinity, do the normal operation.
4239 Else, if not a comparison, return infinity. Else handle the special
4240 comparison rules. Note that most of the cases below won't occur, but
4241 are handled for consistency. */
4244 {
4249 }
4254 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4255 for neither. In real maths, we cannot assume open ended ranges are
4256 the same. But, this is computer arithmetic, where numbers are finite.
4257 We can therefore make the transformation of any unbounded range with
4258 the value Z, Z being greater than any representable number. This permits
4259 us to treat unbounded ranges as equal. */
4263 {
4284 }
4287 }
4288 \f
4289 /* Helper routine for make_range. Perform one step for it, return
4290 new expression if the loop should continue or NULL_TREE if it should
4291 stop. */
4293 tree
4297 {
4303 {
4305 /* We can only do something if the range is testing for zero. */
4314 /* We can only do something if the range is testing for zero
4315 and if the second operand is an integer constant. Note that
4316 saying something is "in" the range we make is done by
4317 complementing IN_P since it will set in the initial case of
4318 being not equal to zero; "out" is leaving it alone. */
4325 {
4346 }
4348 /* If this is an unsigned comparison, we also know that EXP is
4349 greater than or equal to zero. We base the range tests we make
4350 on that fact, so we record it here so we can parse existing
4351 range tests. We test arg0_type since often the return type
4352 of, e.g. EQ_EXPR, is boolean. */
4354 {
4358 NULL_TREE))
4363 /* If the high bound is missing, but we have a nonzero low
4364 bound, reverse the range so it goes from zero to the low bound
4365 minus 1. */
4367 {
4372 }
4373 }
4381 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4382 low and high are non-NULL, then normalize will DTRT. */
4385 {
4390 }
4392 /* (-x) IN [a,b] -> x in [-b, -a] */
4404 /* ~ X -> -X - 1 */
4413 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4414 move a constant to the other side. */
4419 /* If EXP is signed, any overflow in the computation is undefined,
4420 so we don't worry about it so long as our computations on
4421 the bounds don't overflow. For unsigned, overflow is defined
4422 and this is exactly the right thing. */
4434 normalize:
4435 /* Check for an unsigned range which has wrapped around the maximum
4436 value thus making n_high < n_low, and normalize it. */
4438 {
4444 /* If the range is of the form +/- [ x+1, x ], we won't
4445 be able to normalize it. But then, it represents the
4446 whole range or the empty set, so make it
4447 +/- [ -, - ]. */
4451 else
4453 }
4454 else
4462 CASE_CONVERT:
4480 /* If we're converting arg0 from an unsigned type, to exp,
4481 a signed type, we will be doing the comparison as unsigned.
4482 The tests above have already verified that LOW and HIGH
4483 are both positive.
4485 So we have to ensure that we will handle large unsigned
4486 values the same way that the current signed bounds treat
4487 negative values. */
4490 {
4491 tree high_positive;
4492 tree equiv_type;
4493 /* For fixed-point modes, we need to pass the saturating flag
4494 as the 2nd parameter. */
4496 equiv_type
4499 else
4500 equiv_type
4503 /* A range without an upper bound is, naturally, unbounded.
4504 Since convert would have cropped a very large value, use
4505 the max value for the destination type. */
4506 high_positive
4513 high_positive),
4516 /* If the low bound is specified, "and" the range with the
4517 range for which the original unsigned value will be
4518 positive. */
4520 {
4523 integer_zero_node),
4524 high_positive))
4528 }
4529 else
4530 {
4531 /* Otherwise, "or" the range with the range of the input
4532 that will be interpreted as negative. */
4535 integer_zero_node),
4536 high_positive))
4540 }
4541 }
4550 }
4551 }
4553 /* Given EXP, a logical expression, set the range it is testing into
4554 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4555 actually being tested. *PLOW and *PHIGH will be made of the same
4556 type as the returned expression. If EXP is not a comparison, we
4557 will most likely not be returning a useful value and range. Set
4558 *STRICT_OVERFLOW_P to true if the return value is only valid
4559 because signed overflow is undefined; otherwise, do not change
4560 *STRICT_OVERFLOW_P. */
4562 tree
4565 {
4573 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4574 and see if we can refine the range. Some of the cases below may not
4575 happen, but it doesn't seem worth worrying about this. We "continue"
4576 the outer loop when we've changed something; otherwise we "break"
4577 the switch, which will "break" the while. */
4583 {
4589 {
4597 }
4606 }
4608 /* If EXP is a constant, we can evaluate whether this is true or false. */
4610 {
4617 }
4621 }
4622 \f
4623 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4624 type, TYPE, return an expression to test if EXP is in (or out of, depending
4625 on IN_P) the range. Return 0 if the test couldn't be created. */
4627 tree
4630 {
4633 /* Disable this optimization for function pointer expressions
4634 on targets that require function pointer canonicalization. */
4641 {
4647 }
4665 {
4667 {
4671 }
4673 }
4675 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4677 {
4681 {
4683 {
4686 etype
4688 else
4691 }
4694 }
4695 }
4697 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4698 This requires wrap-around arithmetics for the type of the expression.
4699 First make sure that arithmetics in this type is valid, then make sure
4700 that it wraps around. */
4706 {
4709 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4710 for the type in question, as we rely on this here. */
4720 else
4722 }
4732 {
4734 {
4739 }
4741 }
4749 }
4750 \f
4751 /* Return the predecessor of VAL in its type, handling the infinite case. */
4753 static tree
4755 {
4761 else
4764 }
4766 /* Return the successor of VAL in its type, handling the infinite case. */
4768 static tree
4770 {
4776 else
4779 }
4781 /* Given two ranges, see if we can merge them into one. Return 1 if we
4782 can, 0 if we can't. Set the output range into the specified parameters. */
4784 bool
4787 {
4791 tree tem;
4801 /* Make range 0 be the range that starts first, or ends last if they
4802 start at the same value. Swap them if it isn't. */
4805 || (lowequal
4808 {
4812 }
4814 /* Now flag two cases, whether the ranges are disjoint or whether the
4815 second range is totally subsumed in the first. Note that the tests
4816 below are simplified by the ones above. */
4822 /* We now have four cases, depending on whether we are including or
4823 excluding the two ranges. */
4825 {
4826 /* If they don't overlap, the result is false. If the second range
4827 is a subset it is the result. Otherwise, the range is from the start
4828 of the second to the end of the first. */
4833 else
4835 }
4838 {
4839 /* If they don't overlap, the result is the first range. If they are
4840 equal, the result is false. If the second range is a subset of the
4841 first, and the ranges begin at the same place, we go from just after
4842 the end of the second range to the end of the first. If the second
4843 range is not a subset of the first, or if it is a subset and both
4844 ranges end at the same place, the range starts at the start of the
4845 first range and ends just before the second range.
4846 Otherwise, we can't describe this as a single range. */
4852 {
4857 {
4858 /* We are in the weird situation where high0 > high1 but
4859 high1 has no successor. Punt. */
4861 }
4862 }
4864 {
4869 {
4870 /* low0 < low1 but low1 has no predecessor. Punt. */
4872 }
4873 }
4874 else
4876 }
4879 {
4880 /* If they don't overlap, the result is the second range. If the second
4881 is a subset of the first, the result is false. Otherwise,
4882 the range starts just after the first range and ends at the
4883 end of the second. */
4888 else
4889 {
4894 {
4895 /* high1 > high0 but high0 has no successor. Punt. */
4897 }
4898 }
4899 }
4901 else
4902 {
4903 /* The case where we are excluding both ranges. Here the complex case
4904 is if they don't overlap. In that case, the only time we have a
4905 range is if they are adjacent. If the second is a subset of the
4906 first, the result is the first. Otherwise, the range to exclude
4907 starts at the beginning of the first range and ends at the end of the
4908 second. */
4910 {
4915 else
4916 {
4917 /* Canonicalize - [min, x] into - [-, x]. */
4920 {
4925 /* FALLTHROUGH */
4938 }
4940 /* Canonicalize - [x, max] into - [x, -]. */
4943 {
4948 /* FALLTHROUGH */
4964 }
4966 /* The ranges might be also adjacent between the maximum and
4967 minimum values of the given type. For
4968 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4969 return + [x + 1, y - 1]. */
4971 {
4978 }
4979 else
4981 }
4982 }
4985 else
4987 }
4991 }
4992 \f
4994 /* Subroutine of fold, looking inside expressions of the form
4995 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4996 of the COND_EXPR. This function is being used also to optimize
4997 A op B ? C : A, by reversing the comparison first.
4999 Return a folded expression whose code is not a COND_EXPR
5000 anymore, or NULL_TREE if no folding opportunity is found. */
5002 static tree
5005 {
5010 tree tem;
5015 /* If we have A op 0 ? A : -A, consider applying the following
5016 transformations:
5018 A == 0? A : -A same as -A
5019 A != 0? A : -A same as A
5020 A >= 0? A : -A same as abs (A)
5021 A > 0? A : -A same as abs (A)
5022 A <= 0? A : -A same as -abs (A)
5023 A < 0? A : -A same as -abs (A)
5025 None of these transformations work for modes with signed
5026 zeros. If A is +/-0, the first two transformations will
5027 change the sign of the result (from +0 to -0, or vice
5028 versa). The last four will fix the sign of the result,
5029 even though the original expressions could be positive or
5030 negative, depending on the sign of A.
5032 Note that all these transformations are correct if A is
5033 NaN, since the two alternatives (A and -A) are also NaNs. */
5040 /* In the case that A is of the form X-Y, '-A' (arg2) may
5041 have already been folded to Y-X, check for that. */
5049 {
5063 /* Fall through. */
5083 }
5085 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5086 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5087 both transformations are correct when A is NaN: A != 0
5088 is then true, and A == 0 is false. */
5092 {
5097 }
5099 /* Try some transformations of A op B ? A : B.
5101 A == B? A : B same as B
5102 A != B? A : B same as A
5103 A >= B? A : B same as max (A, B)
5104 A > B? A : B same as max (B, A)
5105 A <= B? A : B same as min (A, B)
5106 A < B? A : B same as min (B, A)
5108 As above, these transformations don't work in the presence
5109 of signed zeros. For example, if A and B are zeros of
5110 opposite sign, the first two transformations will change
5111 the sign of the result. In the last four, the original
5112 expressions give different results for (A=+0, B=-0) and
5113 (A=-0, B=+0), but the transformed expressions do not.
5115 The first two transformations are correct if either A or B
5116 is a NaN. In the first transformation, the condition will
5117 be false, and B will indeed be chosen. In the case of the
5118 second transformation, the condition A != B will be true,
5119 and A will be chosen.
5121 The conversions to max() and min() are not correct if B is
5122 a number and A is not. The conditions in the original
5123 expressions will be false, so all four give B. The min()
5124 and max() versions would give a NaN instead. */
5127 /* Avoid these transformations if the COND_EXPR may be used
5128 as an lvalue in the C++ front-end. PR c++/19199. */
5129 && (in_gimple_form
5135 {
5140 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5142 {
5146 }
5149 {
5158 /* In C++ a ?: expression can be an lvalue, so put the
5159 operand which will be used if they are equal first
5160 so that we can convert this back to the
5161 corresponding COND_EXPR. */
5163 {
5172 }
5179 {
5188 }
5203 }
5204 }
5206 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5207 we might still be able to simplify this. For example,
5208 if C1 is one less or one more than C2, this might have started
5209 out as a MIN or MAX and been transformed by this function.
5210 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5216 {
5220 /* We can replace A with C1 in this case. */
5225 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5226 MIN_EXPR, to preserve the signedness of the comparison. */
5228 OEP_ONLY_CONST)
5232 OEP_ONLY_CONST))
5233 {
5236 arg2));
5239 }
5243 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5244 as above. */
5246 OEP_ONLY_CONST)
5250 OEP_ONLY_CONST))
5251 {
5254 arg2));
5257 }
5261 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5262 MAX_EXPR, to preserve the signedness of the comparison. */
5264 OEP_ONLY_CONST)
5268 OEP_ONLY_CONST))
5269 {
5272 arg2));
5274 }
5278 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5280 OEP_ONLY_CONST)
5284 OEP_ONLY_CONST))
5285 {
5288 arg2));
5290 }
5296 }
5299 }
5302 \f
5303 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5304 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5305 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5306 false) >= 2)
5307 #endif
5309 /* EXP is some logical combination of boolean tests. See if we can
5310 merge it into some range test. Return the new tree if so. */
5312 static tree
5315 {
5331 /* If this is an OR operation, invert both sides; we will invert
5332 again at the end. */
5336 /* If both expressions are the same, if we can merge the ranges, and we
5337 can build the range test, return it or it inverted. If one of the
5338 ranges is always true or always false, consider it to be the same
5339 expression as the other. */
5347 {
5351 }
5353 /* On machines where the branch cost is expensive, if this is a
5354 short-circuited branch and the underlying object on both sides
5355 is the same, make a non-short-circuit operation. */
5361 {
5362 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5363 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5364 which cases we can't do this. */
5372 {
5381 {
5384 WARN_STRICT_OVERFLOW_COMPARISON);
5388 }
5389 }
5390 }
5393 }
5394 \f
5395 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5396 bit value. Arrange things so the extra bits will be set to zero if and
5397 only if C is signed-extended to its full width. If MASK is nonzero,
5398 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5400 static tree
5402 {
5405 tree temp;
5410 /* We work by getting just the sign bit into the low-order bit, then
5411 into the high-order bit, then sign-extend. We then XOR that value
5412 with C. */
5415 /* We must use a signed type in order to get an arithmetic right shift.
5416 However, we must also avoid introducing accidental overflows, so that
5417 a subsequent call to integer_zerop will work. Hence we must
5418 do the type conversion here. At this point, the constant is either
5419 zero or one, and the conversion to a signed type can never overflow.
5420 We could get an overflow if this conversion is done anywhere else. */
5429 /* If necessary, convert the type back to match the type of C. */
5434 }
5435 \f
5436 /* For an expression that has the form
5437 (A && B) || ~B
5438 or
5439 (A || B) && ~B,
5440 we can drop one of the inner expressions and simplify to
5441 A || ~B
5442 or
5443 A && ~B
5444 LOC is the location of the resulting expression. OP is the inner
5445 logical operation; the left-hand side in the examples above, while CMPOP
5446 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5447 removing a condition that guards another, as in
5448 (A != NULL && A->...) || A == NULL
5449 which we must not transform. If RHS_ONLY is true, only eliminate the
5450 right-most operand of the inner logical operation. */
5452 static tree
5455 {
5473 {
5476 {
5479 }
5480 }
5482 {
5485 {
5488 }
5489 }
5504 }
5506 /* Find ways of folding logical expressions of LHS and RHS:
5507 Try to merge two comparisons to the same innermost item.
5508 Look for range tests like "ch >= '0' && ch <= '9'".
5509 Look for combinations of simple terms on machines with expensive branches
5510 and evaluate the RHS unconditionally.
5512 For example, if we have p->a == 2 && p->b == 4 and we can make an
5513 object large enough to span both A and B, we can do this with a comparison
5514 against the object ANDed with the a mask.
5516 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5517 operations to do this with one comparison.
5519 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5520 function and the one above.
5522 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5523 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5525 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5526 two operands.
5528 We return the simplified tree or 0 if no optimization is possible. */
5530 static tree
5533 {
5534 /* If this is the "or" of two comparisons, we can do something if
5535 the comparisons are NE_EXPR. If this is the "and", we can do something
5536 if the comparisons are EQ_EXPR. I.e.,
5537 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5539 WANTED_CODE is this operation code. For single bit fields, we can
5540 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5541 comparison for one-bit fields. */
5562 /* Start by getting the comparison codes. Fail if anything is volatile.
5563 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5564 it were surrounded with a NE_EXPR. */
5573 {
5577 }
5580 {
5584 }
5595 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5598 {
5601 {
5606 }
5609 {
5615 }
5616 }
5621 /* If the RHS can be evaluated unconditionally and its operands are
5622 simple, it wins to evaluate the RHS unconditionally on machines
5623 with expensive branches. In this case, this isn't a comparison
5624 that can be merged. */
5631 {
5632 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5643 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5653 }
5655 /* See if the comparisons can be merged. Then get all the parameters for
5656 each side. */
5681 /* It must be true that the inner operation on the lhs of each
5682 comparison must be the same if we are to be able to do anything.
5683 Then see if we have constants. If not, the same must be true for
5684 the rhs's. */
5693 {
5696 }
5701 else
5704 /* If either comparison code is not correct for our logical operation,
5705 fail. However, we can convert a one-bit comparison against zero into
5706 the opposite comparison against that bit being set in the field. */
5710 {
5712 {
5713 /* Make the left operand unsigned, since we are only interested
5714 in the value of one bit. Otherwise we are doing the wrong
5715 thing below. */
5718 }
5719 else
5721 }
5723 /* This is analogous to the code for l_const above. */
5725 {
5727 {
5730 }
5731 else
5733 }
5735 /* See if we can find a mode that contains both fields being compared on
5736 the left. If we can't, fail. Otherwise, update all constants and masks
5737 to be relative to a field of that size. */
5742 volatilep);
5752 {
5755 }
5763 {
5770 {
5774 }
5775 }
5777 {
5784 {
5788 }
5789 }
5791 /* If the right sides are not constant, do the same for it. Also,
5792 disallow this optimization if a size or signedness mismatch occurs
5793 between the left and right sides. */
5795 {
5798 /* Make sure the two fields on the right
5799 correspond to the left without being swapped. */
5807 volatilep);
5817 {
5820 }
5829 /* Make a mask that corresponds to both fields being compared.
5830 Do this for both items being compared. If the operands are the
5831 same size and the bits being compared are in the same position
5832 then we can do this by masking both and comparing the masked
5833 results. */
5837 {
5851 }
5853 /* There is still another way we can do something: If both pairs of
5854 fields being compared are adjacent, we may be able to make a wider
5855 field containing them both.
5857 Note that we still must mask the lhs/rhs expressions. Furthermore,
5858 the mask must be shifted to account for the shift done by
5859 make_bit_field_ref. */
5864 {
5865 tree type;
5881 /* Convert to the smaller type before masking out unwanted bits. */
5884 {
5886 {
5890 }
5892 {
5896 }
5897 }
5906 }
5909 }
5911 /* Handle the case of comparisons with constants. If there is something in
5912 common between the masks, those bits of the constants must be the same.
5913 If not, the condition is always false. Test for this to avoid generating
5914 incorrect code below. */
5919 {
5921 {
5924 }
5925 else
5926 {
5929 }
5930 }
5932 /* Construct the expression we will return. First get the component
5933 reference we will make. Unless the mask is all ones the width of
5934 that field, perform the mask operation. Then compare with the
5935 merged constant. */
5946 }
5947 \f
5948 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5949 constant. */
5951 static tree
5954 {
5957 tree comp_const;
5958 tree minmax_const;
5960 tree inner;
5971 /* If something does not permit us to optimize, return the original tree. */
5979 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5980 and GT_EXPR, doing the rest with recursive calls using logical
5981 simplifications. */
5983 {
5985 {
5986 tree tem
5993 }
5996 return
5998 optimize_minmax_comparison
6000 optimize_minmax_comparison
6005 /* MAX (X, 0) == 0 -> X <= 0 */
6009 /* MAX (X, 0) == 5 -> X == 5 */
6013 /* MAX (X, 0) == -1 -> false */
6017 /* MIN (X, 0) == 0 -> X >= 0 */
6021 /* MIN (X, 0) == 5 -> false */
6024 else
6025 /* MIN (X, 0) == -1 -> X == -1 */
6030 /* MAX (X, 0) > 0 -> X > 0
6031 MAX (X, 0) > 5 -> X > 5 */
6035 /* MAX (X, 0) > -1 -> true */
6039 /* MIN (X, 0) > 0 -> false
6040 MIN (X, 0) > 5 -> false */
6043 else
6044 /* MIN (X, 0) > -1 -> X > -1 */
6049 }
6050 }
6051 \f
6052 /* T is an integer expression that is being multiplied, divided, or taken a
6053 modulus (CODE says which and what kind of divide or modulus) by a
6054 constant C. See if we can eliminate that operation by folding it with
6055 other operations already in T. WIDE_TYPE, if non-null, is a type that
6056 should be used for the computation if wider than our type.
6058 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6059 (X * 2) + (Y * 4). We must, however, be assured that either the original
6060 expression would not overflow or that overflow is undefined for the type
6061 in the language in question.
6063 If we return a non-null expression, it is an equivalent form of the
6064 original computation, but need not be in the original type.
6066 We set *STRICT_OVERFLOW_P to true if the return values depends on
6067 signed overflow being undefined. Otherwise we do not change
6068 *STRICT_OVERFLOW_P. */
6070 static tree
6073 {
6074 /* To avoid exponential search depth, refuse to allow recursion past
6075 three levels. Beyond that (1) it's highly unlikely that we'll find
6076 something interesting and (2) we've probably processed it before
6077 when we built the inner expression. */
6080 tree ret;
6085 depth++;
6087 depth--;
6090 }
6092 static tree
6095 {
6106 /* Don't deal with constants of zero here; they confuse the code below. */
6116 /* Note that we need not handle conditional operations here since fold
6117 already handles those cases. So just do arithmetic here. */
6119 {
6121 /* For a constant, we can always simplify if we are a multiply
6122 or (for divide and modulus) if it is a multiple of our constant. */
6125 {
6128 /* If the multiplication overflowed, we lost information on it.
6129 See PR68142 and PR69845. */
6133 }
6137 /* If op0 is an expression ... */
6143 /* ... and has wrapping overflow, and its type is smaller
6144 than ctype, then we cannot pass through as widening. */
6149 /* ... or this is a truncation (t is narrower than op0),
6150 then we cannot pass through this narrowing. */
6153 /* ... or signedness changes for division or modulus,
6154 then we cannot pass through this conversion. */
6158 /* ... or has undefined overflow while the converted to
6159 type has not, we cannot do the operation in the inner type
6160 as that would introduce undefined overflow. */
6166 /* Pass the constant down and see if we can make a simplification. If
6167 we can, replace this expression with the inner simplification for
6168 possible later conversion to our or some other type. */
6173 code == MULT_EXPR
6175 strict_overflow_p))))
6180 /* If widening the type changes it from signed to unsigned, then we
6181 must avoid building ABS_EXPR itself as unsigned. */
6183 {
6187 {
6190 }
6192 }
6193 /* If the constant is negative, we cannot simplify this. */
6196 /* FALLTHROUGH */
6198 /* For division and modulus, type can't be unsigned, as e.g.
6199 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6200 For signed types, even with wrapping overflow, this is fine. */
6209 /* If widening the type changes the signedness, then we can't perform
6210 this optimization as that changes the result. */
6214 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6220 {
6227 }
6231 /* If the second operand is constant, this is a multiplication
6232 or floor division, by a power of two, so we can treat it that
6233 way unless the multiplier or divisor overflows. Signed
6234 left-shift overflow is implementation-defined rather than
6235 undefined in C90, so do not convert signed left shift into
6236 multiplication. */
6239 /* const_binop may not detect overflow correctly,
6240 so check for it explicitly here. */
6244 size_one_node,
6245 op1)))
6249 ctype,
6251 t1),
6256 /* See if we can eliminate the operation on both sides. If we can, we
6257 can return a new PLUS or MINUS. If we can't, the only remaining
6258 cases where we can do anything are if the second operand is a
6259 constant. */
6265 /* If not multiplication, we can only do this if both operands
6266 are divisible by c. */
6269 {
6274 }
6276 /* If this was a subtraction, negate OP1 and set it to be an addition.
6277 This simplifies the logic below. */
6279 {
6281 /* If OP1 was not easily negatable, the constant may be OP0. */
6283 {
6286 }
6287 }
6292 /* If either OP1 or C are negative, this optimization is not safe for
6293 some of the division and remainder types while for others we need
6294 to change the code. */
6296 {
6304 }
6306 /* If it's a multiply or a division/modulus operation of a multiple
6307 of our constant, do the operation and verify it doesn't overflow. */
6310 {
6313 /* We allow the constant to overflow with wrapping semantics. */
6317 }
6318 else
6321 /* If we have an unsigned type, we cannot widen the operation since it
6322 will change the result if the original computation overflowed. */
6326 /* If we were able to eliminate our operation from the first side,
6327 apply our operation to the second side and reform the PLUS. */
6331 /* The last case is if we are a multiply. In that case, we can
6332 apply the distributive law to commute the multiply and addition
6333 if the multiplication of the constants doesn't overflow
6334 and overflow is defined. With undefined overflow
6335 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6341 op1);
6346 /* We have a special case here if we are doing something like
6347 (C * 8) % 4 since we know that's zero. */
6350 /* If the multiplication can overflow we cannot optimize this. */
6354 {
6357 }
6359 /* ... fall through ... */
6363 /* If we can extract our operation from the LHS, do so and return a
6364 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6365 do something only if the second operand is a constant. */
6379 /* If these are the same operation types, we can associate them
6380 assuming no overflow. */
6382 {
6399 }
6401 /* If these operations "cancel" each other, we have the main
6402 optimizations of this pass, which occur when either constant is a
6403 multiple of the other, in which case we replace this with either an
6404 operation or CODE or TCODE.
6406 If we have an unsigned type, we cannot do this since it will change
6407 the result if the original computation overflowed. */
6414 {
6416 {
6423 }
6425 {
6432 }
6433 }
6438 }
6441 }
6442 \f
6443 /* Return a node which has the indicated constant VALUE (either 0 or
6444 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6445 and is of the indicated TYPE. */
6447 tree
6449 {
6458 else
6460 }
6463 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6464 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6465 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6466 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6467 COND is the first argument to CODE; otherwise (as in the example
6468 given here), it is the second argument. TYPE is the type of the
6469 original expression. Return NULL_TREE if no simplification is
6470 possible. */
6472 static tree
6477 {
6487 {
6491 /* If this operand throws an expression, then it does not make
6492 sense to try to perform a logical or arithmetic operation
6493 involving it. */
6498 }
6501 {
6506 }
6507 else
6508 /* Detect the case of mixing vector and scalar types - bail out. */
6514 /* This transformation is only worthwhile if we don't have to wrap ARG
6515 in a SAVE_EXPR and the operation can be simplified without recursing
6516 on at least one of the branches once its pushed inside the COND_EXPR. */
6525 {
6529 else
6531 }
6533 {
6537 else
6539 }
6541 /* Check that we have simplified at least one of the branches. */
6546 }
6548 \f
6549 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6551 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6552 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6553 ADDEND is the same as X.
6555 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6556 and finite. The problematic cases are when X is zero, and its mode
6557 has signed zeros. In the case of rounding towards -infinity,
6558 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6559 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6561 bool
6563 {
6567 /* Don't allow the fold with -fsignaling-nans. */
6571 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6575 /* In a vector or complex, we would need to check the sign of all zeros. */
6579 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6583 /* The mode has signed zeros, and we have to honor their sign.
6584 In this situation, there is only one case we can return true for.
6585 X - 0 is the same as X unless rounding towards -infinity is
6586 supported. */
6588 }
6590 /* Subroutine of fold() that optimizes comparisons of a division by
6591 a nonzero integer constant against an integer constant, i.e.
6592 X/C1 op C2.
6594 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6595 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6596 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6598 The function returns the constant folded tree if a simplification
6599 can be made, and NULL_TREE otherwise. */
6601 static tree
6604 {
6612 /* We have to do this the hard way to detect unsigned overflow.
6613 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6619 {
6624 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6628 }
6630 {
6634 {
6653 }
6654 }
6655 else
6656 {
6657 /* A negative divisor reverses the relational operators. */
6663 {
6682 }
6683 }
6686 {
6707 {
6710 }
6715 {
6718 }
6723 {
6726 }
6731 {
6734 }
6739 }
6742 }
6745 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6746 equality/inequality test, then return a simplified form of the test
6747 using a sign testing. Otherwise return NULL. TYPE is the desired
6748 result type. */
6750 static tree
6753 tree result_type)
6754 {
6755 /* If this is testing a single bit, we can optimize the test. */
6759 {
6760 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6761 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6765 /* This is only a win if casting to a signed type is cheap,
6766 i.e. when arg00's type is not a partial mode. */
6769 {
6772 result_type,
6775 }
6776 }
6779 }
6781 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6782 equality/inequality test, then return a simplified form of
6783 the test using shifts and logical operations. Otherwise return
6784 NULL. TYPE is the desired result type. */
6786 tree
6789 {
6790 /* If this is testing a single bit, we can optimize the test. */
6794 {
6803 /* First, see if we can fold the single bit test into a sign-bit
6804 test. */
6806 result_type);
6810 /* Otherwise we have (A & C) != 0 where C is a single bit,
6811 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6812 Similarly for (A & C) == 0. */
6814 /* If INNER is a right shift of a constant and it plus BITNUM does
6815 not overflow, adjust BITNUM and INNER. */
6821 {
6824 }
6826 /* If we are going to be able to omit the AND below, we must do our
6827 operations as unsigned. If we must use the AND, we have a choice.
6828 Normally unsigned is faster, but for some machines signed is. */
6846 /* Put the AND last so it can combine with more things. */
6849 /* Make sure to return the proper type. */
6853 }
6855 }
6857 /* Check whether we are allowed to reorder operands arg0 and arg1,
6858 such that the evaluation of arg1 occurs before arg0. */
6860 static bool
6862 {
6869 }
6871 /* Test whether it is preferable two swap two operands, ARG0 and
6872 ARG1, for example because ARG0 is an integer constant and ARG1
6873 isn't. If REORDER is true, only recommend swapping if we can
6874 evaluate the operands in reverse order. */
6876 bool
6878 {
6896 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6897 for commutative and comparison operators. Ensuring a canonical
6898 form allows the optimizers to find additional redundancies without
6899 having to explicitly check for both orderings. */
6905 /* Put SSA_NAMEs last. */
6911 /* Put variables last. */
6918 }
6921 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6922 means A >= Y && A != MAX, but in this case we know that
6923 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6925 static tree
6927 {
6934 else
6943 {
6946 }
6948 {
6951 }
6952 else
6959 {
6960 /* Convert the pointer types into integer before taking the difference. */
6964 }
6965 else
6972 }
6974 /* Fold a sum or difference of at least one multiplication.
6975 Returns the folded tree or NULL if no simplification could be made. */
6977 static tree
6980 {
6984 /* (A * C) +- (B * C) -> (A+-B) * C.
6985 (A * C) +- A -> A * (C+-1).
6986 We are most concerned about the case where C is a constant,
6987 but other combinations show up during loop reduction. Since
6988 it is not difficult, try all four possibilities. */
6991 {
6994 }
6996 {
6999 }
7000 else
7001 {
7002 /* We cannot generate constant 1 for fract. */
7007 }
7009 {
7012 }
7014 {
7016 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7017 the purpose of this canonicalization. */
7021 {
7024 }
7025 else
7027 }
7028 else
7029 {
7030 /* We cannot generate constant 1 for fract. */
7035 }
7047 /* No identical multiplicands; see if we can find a common
7048 power-of-two factor in non-power-of-two multiplies. This
7049 can help in multi-dimensional array access. */
7052 {
7055 tree maybe_same;
7059 /* Move min of absolute values to int11. */
7061 {
7066 }
7067 else
7071 /* The remainder should not be a constant, otherwise we
7072 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7073 increased the number of multiplications necessary. */
7075 {
7083 }
7084 }
7094 }
7096 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7097 specified by EXPR into the buffer PTR of length LEN bytes.
7098 Return the number of bytes placed in the buffer, or zero
7099 upon failure. */
7101 static int
7103 {
7117 {
7119 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7120 number of bytes. */
7124 {
7131 else
7133 }
7134 else
7139 }
7141 }
7144 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7145 specified by EXPR into the buffer PTR of length LEN bytes.
7146 Return the number of bytes placed in the buffer, or zero
7147 upon failure. */
7149 static int
7151 {
7155 FIXED_VALUE_TYPE value;
7171 }
7174 /* Subroutine of native_encode_expr. Encode the REAL_CST
7175 specified by EXPR into the buffer PTR of length LEN bytes.
7176 Return the number of bytes placed in the buffer, or zero
7177 upon failure. */
7179 static int
7181 {
7187 /* There are always 32 bits in each long, no matter the size of
7188 the hosts long. We handle floating point representations with
7189 up to 192 bits. */
7203 {
7208 {
7215 else
7217 }
7218 else
7224 }
7226 }
7228 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7229 specified by EXPR into the buffer PTR of length LEN bytes.
7230 Return the number of bytes placed in the buffer, or zero
7231 upon failure. */
7233 static int
7235 {
7237 tree part;
7252 }
7255 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7256 specified by EXPR into the buffer PTR of length LEN bytes.
7257 Return the number of bytes placed in the buffer, or zero
7258 upon failure. */
7260 static int
7262 {
7272 {
7274 {
7277 }
7288 }
7290 }
7293 /* Subroutine of native_encode_expr. Encode the STRING_CST
7294 specified by EXPR into the buffer PTR of length LEN bytes.
7295 Return the number of bytes placed in the buffer, or zero
7296 upon failure. */
7298 static int
7300 {
7302 HOST_WIDE_INT total_bytes;
7316 {
7319 {
7322 }
7325 }
7326 else
7329 }
7332 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7333 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7334 buffer PTR of length LEN bytes. If OFF is not -1 then start
7335 the encoding at byte offset OFF and encode at most LEN bytes.
7336 Return the number of bytes placed in the buffer, or zero upon failure. */
7338 int
7340 {
7341 /* We don't support starting at negative offset and -1 is special. */
7346 {
7367 }
7368 }
7371 /* Subroutine of native_interpret_expr. Interpret the contents of
7372 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7373 If the buffer cannot be interpreted, return NULL_TREE. */
7375 static tree
7377 {
7387 }
7390 /* Subroutine of native_interpret_expr. Interpret the contents of
7391 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7392 If the buffer cannot be interpreted, return NULL_TREE. */
7394 static tree
7396 {
7398 double_int result;
7399 FIXED_VALUE_TYPE fixed_value;
7409 }
7412 /* Subroutine of native_interpret_expr. Interpret the contents of
7413 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7414 If the buffer cannot be interpreted, return NULL_TREE. */
7416 static tree
7418 {
7422 /* There are always 32 bits in each long, no matter the size of
7423 the hosts long. We handle floating point representations with
7424 up to 192 bits. */
7425 REAL_VALUE_TYPE r;
7436 {
7437 /* Both OFFSET and BYTE index within a long;
7438 bitpos indexes the whole float. */
7441 {
7448 else
7450 }
7451 else
7452 {
7455 {
7456 /* Reverse bytes within each long, or within the entire float
7457 if it's smaller than a long (for HFmode). */
7460 }
7461 }
7465 }
7469 }
7472 /* Subroutine of native_interpret_expr. Interpret the contents of
7473 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7474 If the buffer cannot be interpreted, return NULL_TREE. */
7476 static tree
7478 {
7493 }
7496 /* Subroutine of native_interpret_expr. Interpret the contents of
7497 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7498 If the buffer cannot be interpreted, return NULL_TREE. */
7500 static tree
7502 {
7515 {
7520 }
7522 }
7525 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7526 the buffer PTR of length LEN as a constant of type TYPE. For
7527 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7528 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7529 return NULL_TREE. */
7531 tree
7533 {
7535 {
7557 }
7558 }
7560 /* Returns true if we can interpret the contents of a native encoding
7561 as TYPE. */
7563 static bool
7565 {
7567 {
7580 }
7581 }
7583 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7584 TYPE at compile-time. If we're unable to perform the conversion
7585 return NULL_TREE. */
7587 static tree
7589 {
7590 /* We support up to 512-bit values (for V8DFmode). */
7594 /* Check that the host and target are sane. */
7603 }
7605 /* Build an expression for the address of T. Folds away INDIRECT_REF
7606 to avoid confusing the gimplify process. */
7608 tree
7610 {
7611 /* The size of the object is not relevant when talking about its address. */
7616 {
7621 }
7631 {
7636 }
7637 else
7641 }
7643 /* Build an expression for the address of T. */
7645 tree
7647 {
7651 }
7653 /* Fold a unary expression of code CODE and type TYPE with operand
7654 OP0. Return the folded expression if folding is successful.
7655 Otherwise, return NULL_TREE. */
7657 tree
7659 {
7660 tree tem;
7661 tree arg0;
7669 {
7672 {
7673 /* Don't use STRIP_NOPS, because signedness of argument type
7674 matters. */
7676 }
7677 else
7678 {
7679 /* Strip any conversions that don't change the mode. This
7680 is safe for every expression, except for a comparison
7681 expression because its signedness is derived from its
7682 operands.
7684 Note that this is done as an internal manipulation within
7685 the constant folder, in order to find the simplest
7686 representation of the arguments so that their form can be
7687 studied. In any cases, the appropriate type conversions
7688 should be put back in the tree that will get out of the
7689 constant folder. */
7691 }
7694 {
7697 {
7701 }
7702 }
7703 }
7710 {
7717 {
7731 /* If this was a conversion, and all we did was to move into
7732 inside the COND_EXPR, bring it back out. But leave it if
7733 it is a conversion from integer to integer and the
7734 result precision is no wider than a word since such a
7735 conversion is cheap and may be optimized away by combine,
7736 while it couldn't if it were outside the COND_EXPR. Then return
7737 so we don't get into an infinite recursion loop taking the
7738 conversion out and then back in. */
7750 && (INTEGRAL_TYPE_P
7763 }
7764 }
7767 {
7773 CASE_CONVERT:
7777 {
7778 /* If we have (type) (a CMP b) and type is an integral type, return
7779 new expression involving the new type. Canonicalize
7780 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7781 non-integral type.
7782 Do not fold the result as that would not simplify further, also
7783 folding again results in recursions. */
7793 }
7795 /* Handle (T *)&A.B.C for A being of type T and B and C
7796 living at offset zero. This occurs frequently in
7797 C++ upcasting and then accessing the base. */
7801 {
7803 tree offset;
7804 machine_mode mode;
7806 tree base
7810 /* If the reference was to a (constant) zero offset, we can use
7811 the address of the base if it has the same base type
7812 as the result type and the pointer type is unqualified. */
7819 }
7823 /* Detect assigning a bitfield. */
7825 && DECL_BIT_FIELD
7827 {
7828 /* Don't leave an assignment inside a conversion
7829 unless assigning a bitfield. */
7831 /* First do the assignment, then return converted constant. */
7836 }
7838 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7839 constants (if x has signed type, the sign bit cannot be set
7840 in c). This folds extension into the BIT_AND_EXPR.
7841 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7842 very likely don't have maximal range for their precision and this
7843 transformation effectively doesn't preserve non-maximal ranges. */
7847 {
7858 <= HOST_BITS_PER_WIDE_INT
7860 {
7864 cst &= HOST_WIDE_INT_M1U
7868 && !flag_syntax_only
7871 {
7875 }
7876 }
7878 {
7883 }
7884 }
7886 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7887 cast (T1)X will fold away. We assume that this happens when X itself
7888 is a cast. */
7892 {
7896 return fold_build_pointer_plus_loc
7898 }
7900 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7901 of the same precision, and X is an integer type not narrower than
7902 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7908 {
7914 }
7916 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7917 type of X and Y (integer types only). */
7922 {
7923 /* Be careful not to introduce new overflows. */
7924 tree mult_type;
7927 else
7931 {
7938 }
7939 }
7945 {
7952 }
7963 /* Convert fabs((double)float) into (double)fabsf(float). */
7966 {
7972 targ0));
7973 }
7977 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7996 /* Note that the operand of this must be an int
7997 and its values must be 0 or 1.
7998 ("true" is a fixed value perhaps depending on the language,
7999 but we don't handle values other than 1 correctly yet.) */
8006 /* Fold *&X to X if X is an lvalue. */
8008 {
8015 }
8021 }
8024 /* If the operation was a conversion do _not_ mark a resulting constant
8025 with TREE_OVERFLOW if the original constant was not. These conversions
8026 have implementation defined behavior and retaining the TREE_OVERFLOW
8027 flag here would confuse later passes such as VRP. */
8028 tree
8031 {
8040 }
8042 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8043 operands OP0 and OP1. LOC is the location of the resulting expression.
8044 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8045 Return the folded expression if folding is successful. Otherwise,
8046 return NULL_TREE. */
8047 static tree
8050 {
8051 tree tem;
8053 /* We only do these simplifications if we are optimizing. */
8057 /* Check for things like (A || B) && (A || C). We can convert this
8058 to A || (B && C). Note that either operator can be any of the four
8059 truth and/or operations and the transformation will still be
8060 valid. Also note that we only care about order for the
8061 ANDIF and ORIF operators. If B contains side effects, this
8062 might change the truth-value of A. */
8069 {
8089 /* This case if tricky because we must either have commutative
8090 operators or else A10 must not have side-effects. */
8096 a01);
8097 }
8099 /* See if we can build a range comparison. */
8105 {
8109 }
8113 {
8117 }
8119 /* Check for the possibility of merging component references. If our
8120 lhs is another similar operation, try to merge its rhs with our
8121 rhs. Then try to merge our lhs and rhs. */
8135 {
8142 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8143 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8144 We don't want to pack more than two leafs to a non-IF AND/OR
8145 expression.
8146 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8147 equal to IF-CODE, then we don't want to add right-hand operand.
8148 If the inner right-hand side of left-hand operand has
8149 side-effects, or isn't simple, then we can't add to it,
8150 as otherwise we might destroy if-sequence. */
8153 /* Needed for sequence points to handle trappings, and
8154 side-effects. */
8156 {
8158 arg1);
8160 tem);
8161 }
8162 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8163 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8166 /* Needed for sequence points to handle trappings, and
8167 side-effects. */
8169 {
8174 }
8175 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8176 into (A OR B).
8177 For sequence point consistancy, we need to check for trapping,
8178 and side-effects. */
8182 }
8185 }
8187 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8188 by changing CODE to reduce the magnitude of constants involved in
8189 ARG0 of the comparison.
8190 Returns a canonicalized comparison tree if a simplification was
8191 possible, otherwise returns NULL_TREE.
8192 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8193 valid if signed overflow is undefined. */
8195 static tree
8199 {
8204 /* Match A +- CST code arg1. We can change this only if overflow
8205 is undefined. */
8208 /* In principle pointers also have undefined overflow behavior,
8209 but that causes problems elsewhere. */
8216 /* Identify the constant in arg0 and its sign. */
8220 /* Overflowed constants and zero will cause problems. */
8225 /* See if we can reduce the magnitude of the constant in
8226 arg0 by changing the comparison code. */
8227 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8231 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8235 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8239 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8243 else
8247 /* Now build the constant reduced in magnitude. But not if that
8248 would produce one outside of its types range. */
8264 }
8266 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8267 overflow further. Try to decrease the magnitude of constants involved
8268 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8269 and put sole constants at the second argument position.
8270 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8272 static tree
8275 {
8276 tree t;
8281 /* Try canonicalization by simplifying arg0. */
8286 {
8290 }
8292 /* Try canonicalization by simplifying arg1 using the swapped
8293 comparison. */
8301 }
8303 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8304 space. This is used to avoid issuing overflow warnings for
8305 expressions like &p->x which can not wrap. */
8307 static bool
8309 {
8316 wide_int wi_offset;
8322 else
8338 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8339 array. */
8341 {
8342 HOST_WIDE_INT base_size;
8347 }
8350 }
8352 /* Return a positive integer when the symbol DECL is known to have
8353 a nonzero address, zero when it's known not to (e.g., it's a weak
8354 symbol), and a negative integer when the symbol is not yet in the
8355 symbol table and so whether or not its address is zero is unknown. */
8356 static int
8358 {
8364 }
8366 /* Subroutine of fold_binary. This routine performs all of the
8367 transformations that are common to the equality/inequality
8368 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8369 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8370 fold_binary should call fold_binary. Fold a comparison with
8371 tree code CODE and type TYPE with operands OP0 and OP1. Return
8372 the folded comparison or NULL_TREE. */
8374 static tree
8377 {
8387 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8389 && (equality_code
8396 {
8397 const enum tree_code
8404 /* If the constant operation overflowed this can be
8405 simplified as a comparison against INT_MAX/INT_MIN. */
8408 {
8412 /* Get the sign of the constant on the lhs if the
8413 operation were VARIABLE + CONST1. */
8417 /* The sign of the constant determines if we overflowed
8418 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8419 Canonicalize to the INT_MIN overflow by swapping the comparison
8420 if necessary. */
8424 /* We now can look at the canonicalized case
8425 VARIABLE + 1 CODE2 INT_MIN
8426 and decide on the result. */
8428 {
8432 return
8438 return
8443 }
8444 }
8445 else
8446 {
8449 "when changing X +- C1 cmp C2 to "
8451 WARN_STRICT_OVERFLOW_COMPARISON);
8453 }
8454 }
8456 /* For comparisons of pointers we can decompose it to a compile time
8457 comparison of the base objects and the offsets into the object.
8458 This requires at least one operand being an ADDR_EXPR or a
8459 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8465 {
8468 machine_mode mode;
8472 /* Get base and offset for the access. Strip ADDR_EXPR for
8473 get_inner_reference, but put it back by stripping INDIRECT_REF
8474 off the base object if possible. indirect_baseN will be true
8475 if baseN is not an address but refers to the object itself. */
8478 {
8479 base0
8485 else
8487 }
8489 {
8493 {
8494 base0
8501 else
8503 }
8506 else
8510 {
8516 {
8519 }
8520 }
8521 }
8525 {
8526 base1
8532 else
8534 }
8536 {
8540 {
8541 base1
8548 else
8550 }
8553 else
8557 {
8563 {
8566 }
8567 }
8568 }
8570 /* If we have equivalent bases we might be able to simplify. */
8574 {
8575 /* We can fold this expression to a constant if the non-constant
8576 offset parts are equal. */
8580 && (equality_code
8581 || (indirect_base0
8585 {
8591 "occur when comparing P +- C1 with "
8593 WARN_STRICT_OVERFLOW_CONDITIONAL);
8596 {
8610 }
8611 }
8612 /* We can simplify the comparison to a comparison of the variable
8613 offset parts if the constant offset parts are equal.
8614 Be careful to use signed sizetype here because otherwise we
8615 mess with array offsets in the wrong way. This is possible
8616 because pointer arithmetic is restricted to retain within an
8617 object and overflow on pointer differences is undefined as of
8618 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8620 && (equality_code
8621 || (indirect_base0
8624 {
8625 /* By converting to signed sizetype we cover middle-end pointer
8626 arithmetic which operates on unsigned pointer types of size
8627 type size and ARRAY_REF offsets which are properly sign or
8628 zero extended from their type in case it is narrower than
8629 sizetype. */
8632 else
8636 else
8643 "occur when comparing P +- C1 with "
8645 WARN_STRICT_OVERFLOW_COMPARISON);
8648 }
8649 }
8650 /* For equal offsets we can simplify to a comparison of the
8651 base addresses. */
8653 && (indirect_base0
8655 && (indirect_base1
8660 {
8666 }
8667 /* Comparison between an ordinary (non-weak) symbol and a null
8668 pointer can be eliminated since such symbols must have a non
8669 null address. In C, relational expressions between pointers
8670 to objects and null pointers are undefined. The results
8671 below follow the C++ rules with the additional property that
8672 every object pointer compares greater than a null pointer.
8673 */
8676 /* Avoid folding references to struct members at offset 0 to
8677 prevent tests like '&ptr->firstmember == 0' from getting
8678 eliminated. When ptr is null, although the -> expression
8679 is strictly speaking invalid, GCC retains it as a matter
8680 of QoI. See PR c/44555. */
8682 /* The caller guarantees that when one of the arguments is
8683 constant (i.e., null in this case) it is second. */
8685 {
8687 {
8698 }
8699 }
8700 }
8702 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8703 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8704 the resulting offset is smaller in absolute value than the
8705 original one and has the same sign. */
8714 {
8719 tree cst;
8721 "occur when combining constants around "
8724 /* Put the constant on the side where it doesn't overflow and is
8725 of lower absolute value and of same sign than before. */
8732 {
8735 variable1,
8739 }
8747 {
8753 variable2);
8754 }
8755 }
8761 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8762 constant, we can simplify it. */
8767 {
8771 }
8773 /* If we are comparing an expression that just has comparisons
8774 of two integer values, arithmetic expressions of those comparisons,
8775 and constants, we can simplify it. There are only three cases
8776 to check: the two values can either be equal, the first can be
8777 greater, or the second can be greater. Fold the expression for
8778 those three values. Since each value must be 0 or 1, we have
8779 eight possibilities, each of which corresponds to the constant 0
8780 or 1 or one of the six possible comparisons.
8782 This handles common cases like (a > b) == 0 but also handles
8783 expressions like ((x > y) - (y > x)) > 0, which supposedly
8784 occur in macroized code. */
8787 {
8792 /* Don't handle degenerate cases here; they should already
8793 have been handled anyway. */
8802 {
8806 /* We can't just pass T to eval_subst in case cval1 or cval2
8807 was the same as ARG1. */
8809 tree high_result
8813 arg1);
8814 tree equal_result
8818 arg1);
8819 tree low_result
8823 arg1);
8825 /* All three of these results should be 0 or 1. Confirm they are.
8826 Then use those values to select the proper code to use. */
8831 {
8832 /* Make a 3-bit mask with the high-order bit being the
8833 value for `>', the next for '=', and the low for '<'. */
8837 {
8839 /* Always false. */
8860 /* Always true. */
8862 }
8865 {
8869 }
8871 }
8872 }
8873 }
8875 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8876 into a single range test. */
8884 {
8888 }
8891 }
8894 /* Subroutine of fold_binary. Optimize complex multiplications of the
8895 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8896 argument EXPR represents the expression "z" of type TYPE. */
8898 static tree
8900 {
8905 {
8908 }
8910 {
8913 }
8914 else
8915 {
8919 }
8928 }
8931 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8932 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8934 static bool
8936 {
8940 {
8943 }
8945 {
8951 else
8953 }
8954 else
8960 }
8962 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8963 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8964 NULL_TREE otherwise. */
8966 static tree
8968 {
8985 {
8989 }
8992 {
8998 }
8999 else
9001 }
9003 /* Try to fold a pointer difference of type TYPE two address expressions of
9004 array references AREF0 and AREF1 using location LOC. Return a
9005 simplified expression for the difference or NULL_TREE. */
9007 static tree
9010 {
9015 /* If the bases are array references as well, recurse. If the bases
9016 are pointer indirections compute the difference of the pointers.
9017 If the bases are equal, we are set. */
9020 && (base_offset
9024 && (base_offset
9030 {
9036 base_offset,
9039 }
9041 }
9043 /* If the real or vector real constant CST of type TYPE has an exact
9044 inverse, return it, else return NULL. */
9046 tree
9048 {
9049 REAL_VALUE_TYPE r;
9051 machine_mode mode;
9055 {
9071 {
9076 }
9082 }
9083 }
9085 /* Mask out the tz least significant bits of X of type TYPE where
9086 tz is the number of trailing zeroes in Y. */
9087 static wide_int
9089 {
9094 }
9096 /* Return true when T is an address and is known to be nonzero.
9097 For floating point we further ensure that T is not denormal.
9098 Similar logic is present in nonzero_address in rtlanal.h.
9100 If the return value is based on the assumption that signed overflow
9101 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9102 change *STRICT_OVERFLOW_P. */
9104 static bool
9106 {
9110 /* Doing something useful for floating point would need more work. */
9116 {
9119 strict_overflow_p);
9125 strict_overflow_p);
9133 }
9136 {
9139 strict_overflow_p);
9147 strict_overflow_p);
9162 strict_overflow_p);
9166 strict_overflow_p);
9169 {
9181 }
9185 }
9187 }
9189 /* Return true when T is an address and is known to be nonzero.
9190 Handle warnings about undefined signed overflow. */
9192 static bool
9194 {
9201 "determining that expression is always "
9203 WARN_STRICT_OVERFLOW_MISC);
9205 }
9207 /* Return true if T is known not to be equal to an integer W. */
9209 bool
9211 {
9213 value_range_type rtype;
9215 {
9224 {
9229 }
9234 /* If T has some known zero bits and W has any of those bits set,
9235 then T is known not to be equal to W. */
9243 }
9244 }
9246 /* Fold a binary expression of code CODE and type TYPE with operands
9247 OP0 and OP1. LOC is the location of the resulting expression.
9248 Return the folded expression if folding is successful. Otherwise,
9249 return NULL_TREE. */
9251 tree
9254 {
9269 /* Strip any conversions that don't change the mode. This is
9270 safe for every expression, except for a comparison expression
9271 because its signedness is derived from its operands. So, in
9272 the latter case, only strip conversions that don't change the
9273 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9274 preserved.
9276 Note that this is done as an internal manipulation within the
9277 constant folder, in order to find the simplest representation
9278 of the arguments so that their form can be studied. In any
9279 cases, the appropriate type conversions should be put back in
9280 the tree that will get out of the constant folder. */
9283 {
9286 }
9287 else
9288 {
9291 }
9293 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9294 constant but we can't do arithmetic on them. */
9296 {
9299 {
9303 }
9304 }
9306 /* If this is a commutative operation, and ARG0 is a constant, move it
9307 to ARG1 to reduce the number of tests below. */
9312 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9313 to ARG1 to reduce the number of tests below. */
9322 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9324 First check for cases where an arithmetic operation is applied to a
9325 compound, conditional, or comparison operation. Push the arithmetic
9326 operation inside the compound or conditional to see if any folding
9327 can then be done. Convert comparison to conditional for this purpose.
9328 The also optimizes non-constant cases that used to be done in
9329 expand_expr.
9331 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9332 one of the operands is a comparison and the other is a comparison, a
9333 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9334 code below would make the expression more complex. Change it to a
9335 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9336 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9349 {
9353 boolean_type_node,
9361 }
9365 {
9367 {
9372 tem);
9373 }
9376 {
9381 tem);
9382 }
9387 {
9393 }
9398 {
9404 }
9405 }
9408 {
9410 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9413 {
9419 }
9421 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9424 {
9425 tree base;
9426 HOST_WIDE_INT coffset;
9435 }
9440 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9446 arg1),
9448 arg0)));
9454 {
9455 /* X + (X / CST) * -CST is X % CST. */
9460 {
9469 cst0));
9470 }
9471 }
9473 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9474 one. Make sure the type is not saturating and has the signedness of
9475 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9476 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9483 {
9487 }
9490 {
9491 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9492 (plus (plus (mult) (mult)) (foo)) so that we can
9493 take advantage of the factoring cases below. */
9502 {
9508 else
9521 parg0),
9523 marg)),
9527 return
9533 parg1)));
9534 }
9535 }
9536 else
9537 {
9538 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9539 to __complex__ ( x, y ). This is not the same for SNaNs or
9540 if signed zeros are involved. */
9544 {
9551 {
9555 {
9561 }
9563 {
9569 }
9570 }
9571 }
9579 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9580 We associate floats only if the user has specified
9581 -fassociative-math. */
9585 {
9590 {
9591 tree tree0;
9594 }
9595 }
9596 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9597 We associate floats only if the user has specified
9598 -fassociative-math. */
9602 {
9607 {
9608 tree tree0;
9611 }
9612 }
9613 }
9615 bit_rotate:
9616 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9617 is a rotate of A by C1 bits. */
9618 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9619 is a rotate of A by B bits. */
9620 {
9622 tree rtype;
9631 /* Only create rotates in complete modes. Other cases are not
9632 expanded properly. */
9635 {
9649 {
9653 code0 == LSHIFT_EXPR
9657 }
9659 {
9667 element_precision
9671 return
9674 ? LROTATE_EXPR
9679 }
9681 {
9689 element_precision
9693 return fold_convert_loc
9696 ? LROTATE_EXPR
9700 }
9701 }
9702 }
9704 associate:
9705 /* In most languages, can't associate operations on floats through
9706 parentheses. Rather than remember where the parentheses were, we
9707 don't associate floats at all, unless the user has specified
9708 -fassociative-math.
9709 And, we need to make sure type is not saturating. */
9713 {
9719 /* Split both trees into variables, constants, and literals. Then
9720 associate each group together, the constants with literals,
9721 then the result with variables. This increases the chances of
9722 literals being recombined later and of generating relocatable
9723 expressions for the sum of a constant and literal. */
9729 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9733 /* With undefined overflow prefer doing association in a type
9734 which wraps on overflow, if that is one of the operand types. */
9737 {
9745 }
9747 /* With undefined overflow we can only associate constants with one
9748 variable, and constants whose association doesn't overflow. */
9751 {
9753 {
9759 {
9762 }
9769 {
9772 }
9778 /* The only case we can still associate with two variables
9779 is if they cancel out. */
9783 }
9784 }
9786 /* Only do something if we found more than two objects. Otherwise,
9787 nothing has changed and we risk infinite recursion. */
9793 {
9805 /* Preserve the MINUS_EXPR if the negative part of the literal is
9806 greater than the positive part. Otherwise, the multiplicative
9807 folding code (i.e extract_muldiv) may be fooled in case
9808 unsigned constants are subtracted, like in the following
9809 example: ((X*2 + 4) - 8U)/2. */
9811 {
9815 {
9819 }
9820 else
9821 {
9825 }
9826 }
9828 /* Don't introduce overflows through reassociation. */
9835 {
9837 return
9841 else
9842 {
9845 return
9849 }
9850 }
9853 return
9856 }
9857 }
9862 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9871 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9872 __complex__ ( x, -y ). This is not the same for SNaNs or if
9873 signed zeros are involved. */
9877 {
9884 {
9888 {
9890 arg1r ? arg1r
9895 }
9897 {
9901 arg1i ? arg1i
9904 }
9905 }
9906 }
9908 /* A - B -> A + (-B) if B is easily negatable. */
9912 /* Avoid this transformation if B is a positive REAL_CST. */
9920 /* Fold &a[i] - &a[j] to i-j. */
9925 {
9931 }
9934 && flag_unsafe_math_optimizations
9940 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9941 one. Make sure the type is not saturating and has the signedness of
9942 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9943 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9950 {
9954 }
9960 {
9961 /* Transform x * -C into -x * C if x is easily negatable. */
9971 /* (A + A) * C -> A * 2 * C */
9983 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9984 sign-changing only. */
9994 {
9997 "occur when simplifying "
9999 WARN_STRICT_OVERFLOW_MISC);
10001 }
10003 /* Optimize z * conj(z) for integer complex numbers. */
10010 }
10011 else
10012 {
10013 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10014 This is not the same for NaNs or if signed zeros are
10015 involved. */
10021 {
10024 return
10030 return
10035 }
10037 /* Optimize z * conj(z) for floating point complex numbers.
10038 Guarded by flag_unsafe_math_optimizations as non-finite
10039 imaginary components don't produce scalar results. */
10050 {
10052 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10054 && optimize
10056 {
10060 {
10063 }
10064 }
10065 }
10066 }
10070 /* Canonicalize (X & C1) | C2. */
10074 {
10079 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10087 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10092 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10093 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10094 mode which allows further optimizations. */
10099 {
10103 {
10106 }
10107 }
10114 c3)),
10115 arg1);
10116 }
10118 /* See if this can be simplified into a rotate first. If that
10119 is unsuccessful continue in the association code. */
10123 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10131 /* See if this can be simplified into a rotate first. If that
10132 is unsuccessful continue in the association code. */
10136 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10141 {
10142 tree tem2;
10149 }
10150 /* Fold ~X & 1 as (X & 1) == 0. */
10154 {
10155 tree tem2;
10162 }
10163 /* Fold !X & 1 as X == 0. */
10166 {
10170 }
10172 /* Fold (X ^ Y) & Y as ~X & Y. */
10175 {
10180 }
10181 /* Fold (X ^ Y) & X as ~Y & X. */
10185 {
10190 }
10191 /* Fold X & (X ^ Y) as X & ~Y. */
10194 {
10199 }
10200 /* Fold X & (Y ^ X) as ~Y & X. */
10204 {
10209 }
10211 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10212 multiple of 1 << CST. */
10214 {
10221 }
10223 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10224 bits from CST2. */
10228 {
10236 {
10237 /* Avoid the transform if arg1 is a mask of some
10238 mode which allows further optimizations. */
10245 }
10246 }
10248 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10249 ((A & N) + B) & M -> (A + B) & M
10250 Similarly if (N & M) == 0,
10251 ((A | N) + B) & M -> (A + B) & M
10252 and for - instead of + (or unary - instead of +)
10253 and/or ^ instead of |.
10254 If B is constant and (B & M) == 0, fold into A & M. */
10256 {
10265 {
10268 wide_int cst0;
10270 /* Now we know that arg0 is (C + D) or (C - D) or
10271 -C and arg1 (M) is == (1LL << cst) - 1.
10272 Store C into PMOP[0] and D into PMOP[1]. */
10276 {
10279 }
10286 {
10296 {
10299 }
10302 /* If C or D is of the form (A & N) where
10303 (N & M) == M, or of the form (A | N) or
10304 (A ^ N) where (N & M) == 0, replace it with A. */
10308 /* If C or D is a N where (N & M) == 0, it can be
10309 omitted (assumed 0). */
10317 }
10319 /* Only build anything new if we optimized one or both arguments
10320 above. */
10324 {
10327 {
10328 /* Perform the operations in a type that has defined
10329 overflow behavior. */
10335 }
10340 {
10348 else
10350 }
10353 else
10356 /* TEM is now the new binary +, - or unary - replacement. */
10360 }
10361 }
10362 }
10364 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10367 {
10372 return
10374 }
10379 /* Don't touch a floating-point divide by zero unless the mode
10380 of the constant can represent infinity. */
10386 /* (-A) / (-B) -> A / B */
10398 /* Fall through */
10401 /* Simplify A / (B << N) where A and B are positive and B is
10402 a power of 2, to A >> (N + log2(B)). */
10407 {
10410 {
10418 WARN_STRICT_OVERFLOW_MISC);
10424 }
10425 }
10427 /* Fall through */
10435 /* Convert -A / -B to A / B when the type is signed and overflow is
10436 undefined. */
10440 {
10443 "when distributing negation across "
10445 WARN_STRICT_OVERFLOW_MISC);
10450 }
10454 {
10457 "when distributing negation across "
10459 WARN_STRICT_OVERFLOW_MISC);
10464 }
10466 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10467 operation, EXACT_DIV_EXPR.
10469 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10470 At one time others generated faster code, it's not clear if they do
10471 after the last round to changes to the DIV code in expmed.c. */
10482 {
10486 WARN_STRICT_OVERFLOW_MISC);
10488 }
10500 {
10504 WARN_STRICT_OVERFLOW_MISC);
10506 }
10514 /* Since negative shift count is not well-defined,
10515 don't try to compute it in the compiler. */
10521 /* If we have a rotate of a bit operation with the rotate count and
10522 the second operand of the bit operation both constant,
10523 permute the two operations. */
10529 {
10537 }
10539 /* Two consecutive rotates adding up to the some integer
10540 multiple of the precision of the type can be ignored. */
10555 /* Note that the operands of this must be ints
10556 and their values must be 0 or 1.
10557 ("true" is a fixed value perhaps depending on the language.) */
10558 /* If first arg is constant zero, return it. */
10562 /* If either arg is constant true, drop it. */
10566 /* Preserve sequence points. */
10569 /* If second arg is constant zero, result is zero, but first arg
10570 must be evaluated. */
10573 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10574 case will be handled here. */
10578 /* !X && X is always false. */
10582 /* X && !X is always false. */
10587 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10588 means A >= Y && A != MAX, but in this case we know that
10589 A < X <= MAX. */
10593 {
10601 }
10610 /* Note that the operands of this must be ints
10611 and their values must be 0 or true.
10612 ("true" is a fixed value perhaps depending on the language.) */
10613 /* If first arg is constant true, return it. */
10617 /* If either arg is constant zero, drop it. */
10621 /* Preserve sequence points. */
10624 /* If second arg is constant true, result is true, but we must
10625 evaluate first arg. */
10628 /* Likewise for first arg, but note this only occurs here for
10629 TRUTH_OR_EXPR. */
10633 /* !X || X is always true. */
10637 /* X || !X is always true. */
10642 /* (X && !Y) || (!X && Y) is X ^ Y */
10645 {
10662 }
10671 /* If the second arg is constant zero, drop it. */
10674 /* If the second arg is constant true, this is a logical inversion. */
10676 {
10679 }
10680 /* Identical arguments cancel to zero. */
10684 /* !X ^ X is always true. */
10689 /* X ^ !X is always true. */
10705 /* bool_var != 1 becomes !bool_var. */
10712 /* bool_var == 0 becomes !bool_var. */
10719 /* !exp != 0 becomes !exp */
10724 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10733 {
10739 }
10741 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10750 {
10756 }
10758 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10766 code == NE_EXPR
10770 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10778 code == NE_EXPR
10782 /* If this is an EQ or NE comparison with zero and ARG0 is
10783 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10784 two operations, but the latter can be done in one less insn
10785 on machines that have only two-operand insns or on which a
10786 constant cannot be the first operand. */
10789 {
10794 {
10801 arg1);
10802 }
10805 {
10812 arg1);
10813 }
10814 }
10816 /* If this is an NE or EQ comparison of zero against the result of a
10817 signed MOD operation whose second operand is a power of 2, make
10818 the MOD operation unsigned since it is simpler and equivalent. */
10826 {
10836 }
10838 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10839 C1 is a valid shift constant, and C2 is a power of two, i.e.
10840 a single bit. */
10844 == INTEGER_CST
10847 {
10852 /* Check for a valid shift count. */
10854 {
10858 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10859 can be rewritten as (X & (C2 << C1)) != 0. */
10861 {
10866 }
10867 /* Otherwise, for signed (arithmetic) shifts,
10868 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10869 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10873 /* Otherwise, of unsigned (logical) shifts,
10874 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10875 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10876 else
10880 arg000);
10881 }
10882 }
10884 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10885 Similarly for NE_EXPR. */
10889 {
10893 tree dandnotc
10896 notc);
10900 }
10902 /* If this is a comparison of a field, we may be able to simplify it. */
10905 /* Handle the constant case even without -O
10906 to make sure the warnings are given. */
10908 {
10912 }
10914 /* Optimize comparisons of strlen vs zero to a compare of the
10915 first character of the string vs zero. To wit,
10916 strlen(ptr) == 0 => *ptr == 0
10917 strlen(ptr) != 0 => *ptr != 0
10918 Other cases should reduce to one of these two (or a constant)
10919 due to the return value of strlen being unsigned. */
10922 {
10930 {
10935 }
10936 }
10938 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10939 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10943 {
10948 {
10950 {
10953 }
10956 }
10957 }
10959 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10960 (X & C) == 0 when C is a single bit. */
10965 {
10972 arg1));
10973 }
10975 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10976 constant C is a power of two, i.e. a single bit. */
10983 {
10987 }
10989 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10990 when is C is a power of two, i.e. a single bit. */
10997 {
11003 }
11007 {
11010 }
11012 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11015 {
11028 arg01),
11037 arg01),
11046 arg00),
11055 arg00),
11057 }
11061 {
11068 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11069 operand_equal_p guarantees no side-effects so we don't need
11070 to use omit_one_operand on Z. */
11074 arg10));
11078 arg11));
11082 arg10));
11086 arg11));
11088 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11091 {
11097 }
11098 }
11100 /* Attempt to simplify equality/inequality comparisons of complex
11101 values. Only lower the comparison if the result is known or
11102 can be simplified to a single scalar comparison. */
11107 {
11112 {
11115 }
11116 else
11117 {
11120 }
11123 {
11126 }
11127 else
11128 {
11131 }
11135 {
11137 {
11142 }
11143 else
11144 {
11149 }
11150 }
11154 {
11156 {
11161 }
11162 else
11163 {
11168 }
11169 }
11170 }
11182 /* Transform comparisons of the form X +- C CMP X. */
11189 {
11196 else
11199 /* (X - c) > X becomes false. */
11203 {
11207 "occur when assuming that (X - c) > X "
11209 WARN_STRICT_OVERFLOW_ALL);
11211 }
11213 /* Likewise (X + c) < X becomes false. */
11217 {
11221 "occur when assuming that "
11223 WARN_STRICT_OVERFLOW_ALL);
11225 }
11227 /* Convert (X - c) <= X to true. */
11232 {
11236 "occur when assuming that "
11238 WARN_STRICT_OVERFLOW_ALL);
11240 }
11242 /* Convert (X + c) >= X to true. */
11247 {
11251 "occur when assuming that "
11253 WARN_STRICT_OVERFLOW_ALL);
11255 }
11258 {
11259 /* Convert X + c > X and X - c < X to true for integers. */
11263 {
11266 "not occur when assuming that "
11268 WARN_STRICT_OVERFLOW_ALL);
11270 }
11275 {
11278 "not occur when assuming that "
11280 WARN_STRICT_OVERFLOW_ALL);
11282 }
11284 /* Convert X + c <= X and X - c >= X to false for integers. */
11288 {
11291 "not occur when assuming that "
11293 WARN_STRICT_OVERFLOW_ALL);
11295 }
11300 {
11303 "not occur when assuming that "
11305 WARN_STRICT_OVERFLOW_ALL);
11307 }
11308 }
11309 }
11311 /* If we are comparing an ABS_EXPR with a constant, we can
11312 convert all the cases into explicit comparisons, but they may
11313 well not be faster than doing the ABS and one comparison.
11314 But ABS (X) <= C is a range comparison, which becomes a subtraction
11315 and a comparison, and is probably faster. */
11329 /* Convert ABS_EXPR<x> >= 0 to true. */
11336 {
11339 "when simplifying comparison of "
11341 WARN_STRICT_OVERFLOW_CONDITIONAL);
11344 arg0);
11345 }
11347 /* Convert ABS_EXPR<x> < 0 to false. */
11352 {
11355 "when simplifying comparison of "
11357 WARN_STRICT_OVERFLOW_CONDITIONAL);
11360 arg0);
11361 }
11363 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11364 and similarly for >= into !=. */
11374 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11375 otherwise Y might be >= # of bits in X's type and thus e.g.
11376 (unsigned char) (1 << Y) for Y 15 might be 0.
11377 If the cast is widening, then 1 << Y should have unsigned type,
11378 otherwise if Y is number of bits in the signed shift type minus 1,
11379 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11380 31 might be 0xffffffff80000000. */
11391 {
11397 }
11409 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11410 {
11422 }
11427 /* When pedantic, a compound expression can be neither an lvalue
11428 nor an integer constant expression. */
11431 /* Don't let (0, 0) be null pointer constant. */
11437 /* An ASSERT_EXPR should never be passed to fold_binary. */
11443 }
11445 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11446 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11447 of GOTO_EXPR. */
11449 static tree
11451 {
11453 {
11460 /* ... fall through ... */
11464 }
11465 }
11467 /* Return whether the sub-tree ST contains a label which is accessible from
11468 outside the sub-tree. */
11470 static bool
11472 {
11473 return
11475 }
11477 /* Fold a ternary expression of code CODE and type TYPE with operands
11478 OP0, OP1, and OP2. Return the folded expression if folding is
11479 successful. Otherwise, return NULL_TREE. */
11481 tree
11484 {
11485 tree tem;
11492 /* If this is a commutative operation, and OP0 is a constant, move it
11493 to OP1 to reduce the number of tests below. */
11502 /* Strip any conversions that don't change the mode. This is safe
11503 for every expression, except for a comparison expression because
11504 its signedness is derived from its operands. So, in the latter
11505 case, only strip conversions that don't change the signedness.
11507 Note that this is done as an internal manipulation within the
11508 constant folder, in order to find the simplest representation of
11509 the arguments so that their form can be studied. In any cases,
11510 the appropriate type conversions should be put back in the tree
11511 that will get out of the constant folder. */
11513 {
11516 }
11519 {
11522 }
11525 {
11528 }
11531 {
11535 {
11541 }
11546 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11547 so all simple results must be passed through pedantic_non_lvalue. */
11549 {
11552 /* Only optimize constant conditions when the selected branch
11553 has the same type as the COND_EXPR. This avoids optimizing
11554 away "c ? x : throw", where the throw has a void type.
11555 Avoid throwing away that operand which contains label. */
11562 }
11564 {
11569 {
11574 {
11582 }
11586 }
11587 }
11589 /* If we have A op B ? A : C, we may be able to convert this to a
11590 simpler expression, depending on the operation and the values
11591 of B and C. Signed zeros prevent all of these transformations,
11592 for reasons given above each one.
11594 Also try swapping the arguments and inverting the conditional. */
11599 {
11603 }
11607 op2,
11610 {
11614 {
11618 }
11619 }
11621 /* If the second operand is simpler than the third, swap them
11622 since that produces better jump optimization results. */
11625 {
11627 /* See if this can be inverted. If it can't, possibly because
11628 it was a floating-point inequality comparison, don't do
11629 anything. */
11633 }
11635 /* Convert A ? 1 : 0 to simply A. */
11640 /* If we try to convert OP0 to our type, the
11641 call to fold will try to move the conversion inside
11642 a COND, which will recurse. In that case, the COND_EXPR
11643 is probably the best choice, so leave it alone. */
11647 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11648 over COND_EXPR in cases such as floating point comparisons. */
11657 arg0)));
11659 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11664 {
11665 /* sign_bit_p looks through both zero and sign extensions,
11666 but for this optimization only sign extensions are
11667 usable. */
11670 {
11673 {
11676 }
11678 }
11679 /* sign_bit_p only checks ARG1 bits within A's precision.
11680 If <sign bit of A> has wider type than A, bits outside
11681 of A's precision in <sign bit of A> need to be checked.
11682 If they are all 0, this optimization needs to be done
11683 in unsigned A's type, if they are all 1 in signed A's type,
11684 otherwise this can't be done. */
11690 {
11692 tree tem_type;
11705 {
11708 }
11710 {
11713 }
11714 else
11716 }
11719 return
11725 arg1)));
11726 }
11728 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11729 already handled above. */
11734 {
11743 }
11745 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11746 is probably obsolete because the first operand should be a
11747 truth value (that's why we have the two cases above), but let's
11748 leave it in until we can confirm this for all front-ends. */
11760 /* Disable the transformations below for vectors, since
11761 fold_binary_op_with_conditional_arg may undo them immediately,
11762 yielding an infinite loop. */
11766 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11775 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11780 {
11782 /* Only perform transformation if ARG0 is easily inverted. */
11786 ? BIT_IOR_EXPR
11789 arg1);
11790 }
11792 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11797 {
11799 /* Only perform transformation if ARG0 is easily inverted. */
11805 op2);
11806 }
11808 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11820 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11821 of fold_ternary on them. */
11831 {
11841 {
11846 {
11854 }
11856 /* Constructor elements can be subvectors. */
11859 {
11863 }
11865 /* We keep an exact subset of the constructor elements. */
11867 {
11873 {
11877 }
11885 CONSTRUCTOR_ELT
11888 }
11889 /* The bitfield references a single constructor element. */
11891 {
11896 else
11900 }
11901 }
11902 }
11904 /* A bit-field-ref that referenced the full argument can be stripped. */
11910 /* On constants we can use native encode/interpret to constant
11911 fold (nearly) all BIT_FIELD_REFs. */
11915 /* This limitation should not be necessary, we just need to
11916 round this up to mode size. */
11918 /* Need bit-shifting of the buffer to relax the following. */
11920 {
11925 /* ??? We cannot tell native_encode_expr to start at
11926 some random byte only. So limit us to a reasonable amount
11927 of work. */
11929 {
11934 {
11940 }
11941 }
11942 }
11947 /* For integers we can decompose the FMA if possible. */
11959 {
11975 {
11980 /* Make sure that the perm value is in an acceptable
11981 range. */
11990 else
11995 }
11998 {
12003 }
12008 {
12013 }
12019 {
12023 }
12028 /* Some targets are deficient and fail to expand a single
12029 argument permutation while still allowing an equivalent
12030 2-argument version. */
12034 {
12037 }
12040 {
12047 }
12051 }
12057 }
12059 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
12060 of an array (or vector). */
12062 tree
12064 {
12069 {
12072 {
12073 /* Static constructors for variably sized objects makes no sense. */
12077 }
12078 }
12089 offset_int max_index;
12094 {
12095 /* Array constructor might explicitly set index, or specify a range,
12096 or leave index NULL meaning that it is next index after previous
12097 one. */
12099 {
12102 else
12103 {
12107 }
12108 }
12109 else
12110 {
12116 }
12118 /* Do we have match? */
12122 }
12124 }
12126 /* Perform constant folding and related simplification of EXPR.
12127 The related simplifications include x*1 => x, x*0 => 0, etc.,
12128 and application of the associative law.
12129 NOP_EXPR conversions may be removed freely (as long as we
12130 are careful not to change the type of the overall expression).
12131 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12132 but we can constant-fold them if they have constant operands. */
12134 #ifdef ENABLE_FOLD_CHECKING
12135 # define fold(x) fold_1 (x)
12137 static
12138 #endif
12139 tree
12141 {
12145 tree tem;
12148 /* Return right away if a constant. */
12152 /* CALL_EXPR-like objects with variable numbers of operands are
12153 treated specially. */
12155 {
12157 {
12160 }
12162 }
12165 {
12170 {
12188 }
12189 }
12192 {
12194 {
12201 {
12206 }
12209 }
12211 /* Return a VECTOR_CST if possible. */
12213 {
12219 tree val;
12225 }
12233 }
12235 #ifdef ENABLE_FOLD_CHECKING
12236 #undef fold
12243 /* When --enable-checking=fold, compute a digest of expr before
12244 and after actual fold call to see if fold did not accidentally
12245 change original expr. */
12247 tree
12249 {
12250 tree ret;
12270 }
12272 void
12274 {
12285 }
12287 static void
12289 {
12291 }
12293 static void
12296 {
12302 recursive_label:
12312 {
12313 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12318 }
12326 {
12327 /* Allow these fields to be modified. */
12328 tree tmp;
12337 {
12340 }
12341 }
12352 {
12355 {
12370 }
12374 {
12387 }
12404 {
12410 }
12413 {
12415 {
12418 }
12420 }
12431 {
12434 }
12444 }
12445 }
12447 /* Helper function for outputting the checksum of a tree T. When
12448 debugging with gdb, you can "define mynext" to be "next" followed
12449 by "call debug_fold_checksum (op0)", then just trace down till the
12450 outputs differ. */
12452 DEBUG_FUNCTION void
12454 {
12469 }
12471 #endif
12473 /* Fold a unary tree expression with code CODE of type TYPE with an
12474 operand OP0. LOC is the location of the resulting expression.
12475 Return a folded expression if successful. Otherwise, return a tree
12476 expression with code CODE of type TYPE with an operand OP0. */
12478 tree
12481 {
12482 tree tem;
12483 #ifdef ENABLE_FOLD_CHECKING
12492 #endif
12498 #ifdef ENABLE_FOLD_CHECKING
12505 #endif
12507 }
12509 /* Fold a binary tree expression with code CODE of type TYPE with
12510 operands OP0 and OP1. LOC is the location of the resulting
12511 expression. Return a folded expression if successful. Otherwise,
12512 return a tree expression with code CODE of type TYPE with operands
12513 OP0 and OP1. */
12515 tree
12518 MEM_STAT_DECL)
12519 {
12520 tree tem;
12521 #ifdef ENABLE_FOLD_CHECKING
12538 #endif
12544 #ifdef ENABLE_FOLD_CHECKING
12559 #endif
12561 }
12563 /* Fold a ternary tree expression with code CODE of type TYPE with
12564 operands OP0, OP1, and OP2. Return a folded expression if
12565 successful. Otherwise, return a tree expression with code CODE of
12566 type TYPE with operands OP0, OP1, and OP2. */
12568 tree
12571 {
12572 tree tem;
12573 #ifdef ENABLE_FOLD_CHECKING
12597 #endif
12604 #ifdef ENABLE_FOLD_CHECKING
12627 #endif
12629 }
12631 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12632 arguments in ARGARRAY, and a null static chain.
12633 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12634 of type TYPE from the given operands as constructed by build_call_array. */
12636 tree
12639 {
12640 tree tem;
12641 #ifdef ENABLE_FOLD_CHECKING
12660 #endif
12666 #ifdef ENABLE_FOLD_CHECKING
12682 #endif
12684 }
12686 /* Perform constant folding and related simplification of initializer
12687 expression EXPR. These behave identically to "fold_buildN" but ignore
12688 potential run-time traps and exceptions that fold must preserve. */
12690 #define START_FOLD_INIT \
12691 int saved_signaling_nans = flag_signaling_nans;\
12692 int saved_trapping_math = flag_trapping_math;\
12693 int saved_rounding_math = flag_rounding_math;\
12694 int saved_trapv = flag_trapv;\
12695 int saved_folding_initializer = folding_initializer;\
12696 flag_signaling_nans = 0;\
12697 flag_trapping_math = 0;\
12698 flag_rounding_math = 0;\
12699 flag_trapv = 0;\
12700 folding_initializer = 1;
12702 #define END_FOLD_INIT \
12703 flag_signaling_nans = saved_signaling_nans;\
12704 flag_trapping_math = saved_trapping_math;\
12705 flag_rounding_math = saved_rounding_math;\
12706 flag_trapv = saved_trapv;\
12707 folding_initializer = saved_folding_initializer;
12709 tree
12712 {
12713 tree result;
12714 START_FOLD_INIT;
12718 END_FOLD_INIT;
12720 }
12722 tree
12725 {
12726 tree result;
12727 START_FOLD_INIT;
12731 END_FOLD_INIT;
12733 }
12735 tree
12738 {
12739 tree result;
12740 START_FOLD_INIT;
12744 END_FOLD_INIT;
12746 }
12748 #undef START_FOLD_INIT
12749 #undef END_FOLD_INIT
12751 /* Determine if first argument is a multiple of second argument. Return 0 if
12752 it is not, or we cannot easily determined it to be.
12754 An example of the sort of thing we care about (at this point; this routine
12755 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12756 fold cases do now) is discovering that
12758 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12760 is a multiple of
12762 SAVE_EXPR (J * 8)
12764 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12766 This code also handles discovering that
12768 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12770 is a multiple of 8 so we don't have to worry about dealing with a
12771 possible remainder.
12773 Note that we *look* inside a SAVE_EXPR only to determine how it was
12774 calculated; it is not safe for fold to do much of anything else with the
12775 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12776 at run time. For example, the latter example above *cannot* be implemented
12777 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12778 evaluation time of the original SAVE_EXPR is not necessarily the same at
12779 the time the new expression is evaluated. The only optimization of this
12780 sort that would be valid is changing
12782 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12784 divided by 8 to
12786 SAVE_EXPR (I) * SAVE_EXPR (J)
12788 (where the same SAVE_EXPR (J) is used in the original and the
12789 transformed version). */
12791 int
12793 {
12801 {
12803 /* Bitwise and provides a power of two multiple. If the mask is
12804 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12807 /* FALLTHRU */
12820 {
12824 /* const_binop may not detect overflow correctly,
12825 so check for it explicitly here. */
12829 size_one_node,
12830 op1)))
12833 }
12837 /* Can't handle conversions from non-integral or wider integral type. */
12843 /* .. fall through ... */
12860 SIGNED);
12864 }
12865 }
12867 #define tree_expr_nonnegative_warnv_p(X, Y) \
12870 #define RECURSE(X) \
12871 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12873 /* Return true if CODE or TYPE is known to be non-negative. */
12875 static bool
12877 {
12880 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12881 have a signed:1 type (where the value is -1 and 0). */
12884 }
12886 /* Return true if (CODE OP0) is known to be non-negative. If the return
12887 value is based on the assumption that signed overflow is undefined,
12888 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12889 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12891 bool
12894 {
12899 {
12901 /* We can't return 1 if flag_wrapv is set because
12902 ABS_EXPR<INT_MIN> = INT_MIN. */
12906 {
12909 }
12917 CASE_CONVERT:
12918 {
12923 {
12927 {
12931 }
12932 }
12934 {
12940 }
12941 }
12946 }
12948 /* We don't know sign of `t', so be conservative and return false. */
12950 }
12952 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12953 value is based on the assumption that signed overflow is undefined,
12954 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12955 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12957 bool
12961 {
12966 {
12972 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12973 both unsigned and at least 2 bits shorter than the result. */
12977 {
12982 {
12986 }
12987 }
12992 {
12993 /* x * x is always non-negative for floating point x
12994 or without overflow. */
12997 {
13002 }
13003 }
13005 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13006 both unsigned and their total bits is shorter than the result. */
13010 {
13029 {
13039 }
13040 }
13067 }
13069 /* We don't know sign of `t', so be conservative and return false. */
13071 }
13073 /* Return true if T is known to be non-negative. If the return
13074 value is based on the assumption that signed overflow is undefined,
13075 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13076 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13078 bool
13080 {
13085 {
13099 /* Limit the depth of recursion to avoid quadratic behavior.
13100 This is expected to catch almost all occurrences in practice.
13101 If this code misses important cases that unbounded recursion
13102 would not, passes that need this information could be revised
13103 to provide it through dataflow propagation. */
13111 }
13112 }
13114 /* Return true if T is known to be non-negative. If the return
13115 value is based on the assumption that signed overflow is undefined,
13116 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13117 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13119 bool
13122 {
13124 {
13125 CASE_CFN_ACOS:
13126 CASE_CFN_ACOSH:
13127 CASE_CFN_CABS:
13128 CASE_CFN_COSH:
13129 CASE_CFN_ERFC:
13130 CASE_CFN_EXP:
13131 CASE_CFN_EXP10:
13132 CASE_CFN_EXP2:
13133 CASE_CFN_FABS:
13134 CASE_CFN_FDIM:
13135 CASE_CFN_HYPOT:
13136 CASE_CFN_POW10:
13137 CASE_CFN_FFS:
13138 CASE_CFN_PARITY:
13139 CASE_CFN_POPCOUNT:
13140 CASE_CFN_CLZ:
13141 CASE_CFN_CLRSB:
13144 /* Always true. */
13147 CASE_CFN_SQRT:
13148 /* sqrt(-0.0) is -0.0. */
13153 CASE_CFN_ASINH:
13154 CASE_CFN_ATAN:
13155 CASE_CFN_ATANH:
13156 CASE_CFN_CBRT:
13157 CASE_CFN_CEIL:
13158 CASE_CFN_ERF:
13159 CASE_CFN_EXPM1:
13160 CASE_CFN_FLOOR:
13161 CASE_CFN_FMOD:
13162 CASE_CFN_FREXP:
13163 CASE_CFN_ICEIL:
13164 CASE_CFN_IFLOOR:
13165 CASE_CFN_IRINT:
13166 CASE_CFN_IROUND:
13167 CASE_CFN_LCEIL:
13168 CASE_CFN_LDEXP:
13169 CASE_CFN_LFLOOR:
13170 CASE_CFN_LLCEIL:
13171 CASE_CFN_LLFLOOR:
13172 CASE_CFN_LLRINT:
13173 CASE_CFN_LLROUND:
13174 CASE_CFN_LRINT:
13175 CASE_CFN_LROUND:
13176 CASE_CFN_MODF:
13177 CASE_CFN_NEARBYINT:
13178 CASE_CFN_RINT:
13179 CASE_CFN_ROUND:
13180 CASE_CFN_SCALB:
13181 CASE_CFN_SCALBLN:
13182 CASE_CFN_SCALBN:
13183 CASE_CFN_SIGNBIT:
13184 CASE_CFN_SIGNIFICAND:
13185 CASE_CFN_SINH:
13186 CASE_CFN_TANH:
13187 CASE_CFN_TRUNC:
13188 /* True if the 1st argument is nonnegative. */
13191 CASE_CFN_FMAX:
13192 /* True if the 1st OR 2nd arguments are nonnegative. */
13195 CASE_CFN_FMIN:
13196 /* True if the 1st AND 2nd arguments are nonnegative. */
13199 CASE_CFN_COPYSIGN:
13200 /* True if the 2nd argument is nonnegative. */
13203 CASE_CFN_POWI:
13204 /* True if the 1st argument is nonnegative or the second
13205 argument is an even integer. */
13211 CASE_CFN_POW:
13212 /* True if the 1st argument is nonnegative or the second
13213 argument is an even integer valued real. */
13215 {
13216 REAL_VALUE_TYPE c;
13217 HOST_WIDE_INT n;
13222 {
13223 REAL_VALUE_TYPE cint;
13227 }
13228 }
13233 }
13235 }
13237 /* Return true if T is known to be non-negative. If the return
13238 value is based on the assumption that signed overflow is undefined,
13239 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13240 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13242 static bool
13244 {
13250 {
13252 {
13256 /* If the initializer is non-void, then it's a normal expression
13257 that will be assigned to the slot. */
13261 /* Otherwise, the initializer sets the slot in some way. One common
13262 way is an assignment statement at the end of the initializer. */
13264 {
13272 else
13274 }
13280 }
13283 {
13289 arg0,
13290 arg1,
13292 }
13305 }
13306 }
13308 #undef RECURSE
13309 #undef tree_expr_nonnegative_warnv_p
13311 /* Return true if T is known to be non-negative. If the return
13312 value is based on the assumption that signed overflow is undefined,
13313 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13314 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13316 bool
13318 {
13325 {
13347 }
13350 {
13376 }
13377 }
13379 /* Return true if `t' is known to be non-negative. Handle warnings
13380 about undefined signed overflow. */
13382 bool
13384 {
13391 "determining that expression is always "
13393 WARN_STRICT_OVERFLOW_MISC);
13395 }
13398 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13399 For floating point we further ensure that T is not denormal.
13400 Similar logic is present in nonzero_address in rtlanal.h.
13402 If the return value is based on the assumption that signed overflow
13403 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13404 change *STRICT_OVERFLOW_P. */
13406 bool
13409 {
13411 {
13414 strict_overflow_p);
13417 {
13423 strict_overflow_p));
13424 }
13429 strict_overflow_p);
13433 }
13436 }
13438 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13439 For floating point we further ensure that T is not denormal.
13440 Similar logic is present in nonzero_address in rtlanal.h.
13442 If the return value is based on the assumption that signed overflow
13443 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13444 change *STRICT_OVERFLOW_P. */
13446 bool
13448 tree type,
13449 tree op0,
13451 {
13454 {
13458 {
13459 /* With the presence of negative values it is hard
13460 to say something. */
13467 /* One of operands must be positive and the other non-negative. */
13468 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13469 overflows, on a twos-complement machine the sum of two
13470 nonnegative numbers can never be zero. */
13472 strict_overflow_p)
13474 strict_overflow_p));
13475 }
13480 {
13482 strict_overflow_p)
13484 strict_overflow_p))
13485 {
13488 }
13489 }
13498 {
13501 }
13508 {
13512 /* When both operands are nonzero, then MAX must be too. */
13514 strict_overflow_p))
13517 /* MAX where operand 0 is positive is positive. */
13519 strict_overflow_p);
13520 }
13521 /* MAX where operand 1 is positive is positive. */
13526 {
13530 }
13535 strict_overflow_p)
13537 strict_overflow_p));
13541 }
13544 }
13546 /* Return true when T is an address and is known to be nonzero.
13547 For floating point we further ensure that T is not denormal.
13548 Similar logic is present in nonzero_address in rtlanal.h.
13550 If the return value is based on the assumption that signed overflow
13551 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13552 change *STRICT_OVERFLOW_P. */
13554 bool
13556 {
13559 {
13564 {
13576 /* For objects in symbol table check if we know they are non-zero.
13577 Don't do anything for variables and functions before symtab is built;
13578 it is quite possible that they will be declared weak later. */
13583 /* Function local objects are never NULL. */
13590 /* Constants are never weak. */
13595 }
13603 {
13607 }
13612 }
13614 }
13616 #define integer_valued_real_p(X) \
13619 #define RECURSE(X) \
13620 ((integer_valued_real_p) (X, depth + 1))
13622 /* Return true if the floating point result of (CODE OP0) has an
13623 integer value. We also allow +Inf, -Inf and NaN to be considered
13624 integer values. Return false for signaling NaN.
13626 DEPTH is the current nesting depth of the query. */
13628 bool
13630 {
13632 {
13639 CASE_CONVERT:
13640 {
13647 }
13651 }
13653 }
13655 /* Return true if the floating point result of (CODE OP0 OP1) has an
13656 integer value. We also allow +Inf, -Inf and NaN to be considered
13657 integer values. Return false for signaling NaN.
13659 DEPTH is the current nesting depth of the query. */
13661 bool
13663 {
13665 {
13675 }
13677 }
13679 /* Return true if the floating point result of calling FNDECL with arguments
13680 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13681 considered integer values. Return false for signaling NaN. If FNDECL
13682 takes fewer than 2 arguments, the remaining ARGn are null.
13684 DEPTH is the current nesting depth of the query. */
13686 bool
13688 {
13690 {
13691 CASE_CFN_CEIL:
13692 CASE_CFN_FLOOR:
13693 CASE_CFN_NEARBYINT:
13694 CASE_CFN_RINT:
13695 CASE_CFN_ROUND:
13696 CASE_CFN_TRUNC:
13699 CASE_CFN_FMIN:
13700 CASE_CFN_FMAX:
13705 }
13707 }
13709 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13710 has an integer value. We also allow +Inf, -Inf and NaN to be
13711 considered integer values. Return false for signaling NaN.
13713 DEPTH is the current nesting depth of the query. */
13715 bool
13717 {
13719 {
13727 /* Limit the depth of recursion to avoid quadratic behavior.
13728 This is expected to catch almost all occurrences in practice.
13729 If this code misses important cases that unbounded recursion
13730 would not, passes that need this information could be revised
13731 to provide it through dataflow propagation. */
13735 depth));
13739 }
13741 }
13743 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13744 has an integer value. We also allow +Inf, -Inf and NaN to be
13745 considered integer values. Return false for signaling NaN.
13747 DEPTH is the current nesting depth of the query. */
13749 static bool
13751 {
13753 {
13764 }
13766 }
13768 #undef RECURSE
13769 #undef integer_valued_real_p
13771 /* Return true if the floating point expression T has an integer value.
13772 We also allow +Inf, -Inf and NaN to be considered integer values.
13773 Return false for signaling NaN.
13775 DEPTH is the current nesting depth of the query. */
13777 bool
13779 {
13785 {
13801 }
13804 {
13810 {
13819 }
13823 }
13824 }
13826 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13827 attempt to fold the expression to a constant without modifying TYPE,
13828 OP0 or OP1.
13830 If the expression could be simplified to a constant, then return
13831 the constant. If the expression would not be simplified to a
13832 constant, then return NULL_TREE. */
13834 tree
13836 {
13839 }
13841 /* Given the components of a unary expression CODE, TYPE and OP0,
13842 attempt to fold the expression to a constant without modifying
13843 TYPE or OP0.
13845 If the expression could be simplified to a constant, then return
13846 the constant. If the expression would not be simplified to a
13847 constant, then return NULL_TREE. */
13849 tree
13851 {
13854 }
13856 /* If EXP represents referencing an element in a constant string
13857 (either via pointer arithmetic or array indexing), return the
13858 tree representing the value accessed, otherwise return NULL. */
13860 tree
13862 {
13866 {
13868 tree index;
13869 tree string;
13874 else
13875 {
13879 /* Optimize the special-case of a zero lower bound.
13881 We convert the low_bound to sizetype to avoid some problems
13882 with constant folding. (E.g. suppose the lower bound is 1,
13883 and its mode is QI. Without the conversion,l (ARRAY
13884 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13885 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13891 }
13904 }
13906 }
13908 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13909 an integer constant, real, or fixed-point constant.
13911 TYPE is the type of the result. */
13913 static tree
13915 {
13919 {
13921 {
13928 }
13935 {
13936 FIXED_VALUE_TYPE f;
13941 /* Propagate overflow flags. */
13945 }
13949 }
13952 }
13954 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13955 an integer constant or real constant.
13957 TYPE is the type of the result. */
13959 tree
13961 {
13965 {
13967 {
13968 /* If the value is unsigned or non-negative, then the absolute value
13969 is the same as the ordinary value. */
13973 /* If the value is negative, then the absolute value is
13974 its negation. */
13975 else
13976 {
13981 }
13982 }
13988 else
13994 }
13997 }
13999 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
14000 constant. TYPE is the type of the result. */
14002 static tree
14004 {
14008 }
14010 /* Given CODE, a relational operator, the target type, TYPE and two
14011 constant operands OP0 and OP1, return the result of the
14012 relational operation. If the result is not a compile time
14013 constant, then return NULL_TREE. */
14015 static tree
14017 {
14020 /* From here on, the only cases we handle are when the result is
14021 known to be a constant. */
14024 {
14028 /* Handle the cases where either operand is a NaN. */
14030 {
14032 {
14060 }
14063 }
14066 }
14069 {
14073 }
14075 /* Handle equality/inequality of complex constants. */
14077 {
14088 else
14090 }
14093 {
14095 {
14096 /* Have vector comparison with scalar boolean result. */
14100 {
14108 }
14110 }
14117 {
14129 }
14132 }
14134 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14136 To compute GT, swap the arguments and do LT.
14137 To compute GE, do LT and invert the result.
14138 To compute LE, swap the arguments, do LT and invert the result.
14139 To compute NE, do EQ and invert the result.
14141 Therefore, the code below must handle only EQ and LT. */
14144 {
14147 }
14149 /* Note that it is safe to invert for real values here because we
14150 have already handled the one case that it matters. */
14154 {
14157 }
14159 /* Compute a result for LT or EQ if args permit;
14160 Otherwise return T. */
14162 {
14165 else
14167 }
14168 else
14174 }
14176 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14177 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14178 itself. */
14180 tree
14182 {
14183 /* If the expression does not have side effects then we don't have to wrap
14184 it with a cleanup point expression. */
14188 /* If the expression is a return, check to see if the expression inside the
14189 return has no side effects or the right hand side of the modify expression
14190 inside the return. If either don't have side effects set we don't need to
14191 wrap the expression in a cleanup point expression. Note we don't check the
14192 left hand side of the modify because it should always be a return decl. */
14194 {
14201 }
14204 }
14206 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14207 of an indirection through OP0, or NULL_TREE if no simplification is
14208 possible. */
14210 tree
14212 {
14214 tree subtype;
14222 {
14225 /* *&CONST_DECL -> to the value of the const decl. */
14228 /* *&p => p; make sure to handle *&"str"[cst] here. */
14230 {
14234 else
14236 }
14237 /* *(foo *)&fooarray => fooarray[0] */
14240 && (!in_gimple_form
14242 {
14252 }
14253 /* *(foo *)&complexfoo => __real__ complexfoo */
14257 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14260 {
14264 }
14265 }
14269 {
14275 {
14276 tree op00type;
14280 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14283 {
14285 unsigned HOST_WIDE_INT max_offset
14290 {
14297 }
14298 }
14299 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14302 {
14306 }
14307 /* ((foo *)&fooarray)[1] => fooarray[1] */
14310 {
14320 }
14321 }
14322 }
14324 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14327 && (!in_gimple_form
14329 {
14330 tree type_domain;
14340 NULL_TREE);
14341 }
14344 }
14346 /* Builds an expression for an indirection through T, simplifying some
14347 cases. */
14349 tree
14351 {
14359 }
14361 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14363 tree
14365 {
14370 else
14372 }
14374 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14375 whose result is ignored. The type of the returned tree need not be
14376 the same as the original expression. */
14378 tree
14380 {
14386 {
14397 else
14403 {
14419 }
14424 }
14425 }
14427 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14429 tree
14431 {
14437 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14438 have to do anything. Only do this when we are not given a const,
14439 because in that case, this check is more expensive than just
14440 doing it. */
14442 {
14447 }
14449 /* If divisor is a power of two, simplify this to bit manipulation. */
14451 {
14453 {
14467 }
14468 else
14469 {
14470 tree t;
14476 }
14477 }
14478 else
14479 {
14484 }
14487 }
14489 /* Likewise, but round down. */
14491 tree
14493 {
14500 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14501 have to do anything. Only do this when we are not given a const,
14502 because in that case, this check is more expensive than just
14503 doing it. */
14505 {
14510 }
14512 /* If divisor is a power of two, simplify this to bit manipulation. */
14514 {
14515 tree t;
14519 }
14520 else
14521 {
14526 }
14529 }
14531 /* Returns the pointer to the base of the object addressed by EXP and
14532 extracts the information about the offset of the access, storing it
14533 to PBITPOS and POFFSET. */
14535 static tree
14538 {
14539 tree core;
14540 machine_mode mode;
14542 HOST_WIDE_INT bitsize;
14546 {
14551 }
14552 else
14553 {
14557 }
14560 }
14562 /* Returns true if addresses of E1 and E2 differ by a constant, false
14563 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14565 bool
14567 {
14581 {
14591 }
14593 {
14594 /* If only one of the offsets is non-constant, the difference cannot
14595 be a constant. */
14597 }
14598 else
14603 }
14605 /* Return OFF converted to a pointer offset type suitable as offset for
14606 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14607 tree
14609 {
14611 }
14613 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14614 tree
14616 {
14619 }
14621 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14622 tree
14624 {
14627 }
14629 /* Return a char pointer for a C string if it is a string constant
14630 or sum of string constant and integer constant. */
14634 {
14635 tree offset_node;
14648 }