| blob | ad4770b43d2ae344930339bd65f09af592765329 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2017 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. */
83 /* Nonzero if we are folding constants inside an initializer; zero
84 otherwise. */
87 /* The following constants represent a bit based encoding of GCC's
88 comparison operators. This encoding simplifies transformations
89 on relational comparison operators, such as AND and OR. */
107 };
145 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
146 Otherwise, return LOC. */
148 static location_t
150 {
153 }
155 /* Similar to protected_set_expr_location, but never modify x in place,
156 if location can and needs to be set, unshare it. */
160 {
166 {
169 }
171 }
172 \f
173 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
174 division and returns the quotient. Otherwise returns
175 NULL_TREE. */
177 tree
179 {
180 widest_int quo;
187 }
188 \f
189 /* This is nonzero if we should defer warnings about undefined
190 overflow. This facility exists because these warnings are a
191 special case. The code to estimate loop iterations does not want
192 to issue any warnings, since it works with expressions which do not
193 occur in user code. Various bits of cleanup code call fold(), but
194 only use the result if it has certain characteristics (e.g., is a
195 constant); that code only wants to issue a warning if the result is
196 used. */
200 /* If a warning about undefined overflow is deferred, this is the
201 warning. Note that this may cause us to turn two warnings into
202 one, but that is fine since it is sufficient to only give one
203 warning per expression. */
207 /* If a warning about undefined overflow is deferred, this is the
208 level at which the warning should be emitted. */
212 /* Start deferring overflow warnings. We could use a stack here to
213 permit nested calls, but at present it is not necessary. */
215 void
217 {
219 }
221 /* Stop deferring overflow warnings. If there is a pending warning,
222 and ISSUE is true, then issue the warning if appropriate. STMT is
223 the statement with which the warning should be associated (used for
224 location information); STMT may be NULL. CODE is the level of the
225 warning--a warn_strict_overflow_code value. This function will use
226 the smaller of CODE and the deferred code when deciding whether to
227 issue the warning. CODE may be zero to mean to always use the
228 deferred code. */
230 void
232 {
234 location_t locus;
239 {
245 }
256 /* Use the smallest code level when deciding to issue the
257 warning. */
266 else
269 }
271 /* Stop deferring overflow warnings, ignoring any deferred
272 warnings. */
274 void
276 {
278 }
280 /* Whether we are deferring overflow warnings. */
282 bool
284 {
286 }
288 /* This is called when we fold something based on the fact that signed
289 overflow is undefined. */
291 void
293 {
295 {
298 {
301 }
302 }
305 }
306 \f
307 /* Return true if the built-in mathematical function specified by CODE
308 is odd, i.e. -f(x) == f(-x). */
310 bool
312 {
314 {
315 CASE_CFN_ASIN:
316 CASE_CFN_ASINH:
317 CASE_CFN_ATAN:
318 CASE_CFN_ATANH:
319 CASE_CFN_CASIN:
320 CASE_CFN_CASINH:
321 CASE_CFN_CATAN:
322 CASE_CFN_CATANH:
323 CASE_CFN_CBRT:
324 CASE_CFN_CPROJ:
325 CASE_CFN_CSIN:
326 CASE_CFN_CSINH:
327 CASE_CFN_CTAN:
328 CASE_CFN_CTANH:
329 CASE_CFN_ERF:
330 CASE_CFN_LLROUND:
331 CASE_CFN_LROUND:
332 CASE_CFN_ROUND:
333 CASE_CFN_SIN:
334 CASE_CFN_SINH:
335 CASE_CFN_TAN:
336 CASE_CFN_TANH:
337 CASE_CFN_TRUNC:
340 CASE_CFN_LLRINT:
341 CASE_CFN_LRINT:
342 CASE_CFN_NEARBYINT:
343 CASE_CFN_RINT:
348 }
350 }
352 /* Check whether we may negate an integer constant T without causing
353 overflow. */
355 bool
357 {
358 tree type;
367 }
369 /* Determine whether an expression T can be cheaply negated using
370 the function negate_expr without introducing undefined overflow. */
372 static bool
374 {
375 tree type;
384 {
389 /* Check that -CST will not overflow type. */
402 /* We want to canonicalize to positive real constants. Pretend
403 that only negative ones can be easily negated. */
411 {
422 }
437 /* -(A + B) -> (-B) - A. */
440 /* -(A + B) -> (-A) - B. */
444 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
453 /* INT_MIN/n * n doesn't overflow while negating one operand it does
454 if n is a (negative) power of two. */
463 /* Fall through. */
478 /* In general we can't negate B in A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. */
489 /* Negate -((double)float) as (double)(-float). */
491 {
495 }
499 /* Negate -f(x) as f(-x). */
505 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
507 {
511 }
516 }
518 }
520 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
521 simplification is possible.
522 If negate_expr_p would return true for T, NULL_TREE will never be
523 returned. */
525 static tree
527 {
529 tree tem;
532 {
533 /* Convert - (~A) to A + 1. */
559 {
564 }
568 {
573 {
577 }
580 }
603 {
604 /* -(A + B) -> (-B) - A. */
606 {
610 }
612 /* -(A + B) -> (-A) - B. */
614 {
618 }
619 }
623 /* - (A - B) -> B - A */
634 /* Fall through. */
638 {
647 }
659 /* In general we can't negate B in A / B, because if A is INT_MIN and
660 B is 1, we may turn this into INT_MIN / -1 which is undefined
661 and actually traps on some architectures. */
673 /* Convert -((double)float) into (double)(-float). */
675 {
679 }
683 /* Negate -f(x) as f(-x). */
686 {
692 }
696 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
698 {
701 {
708 }
709 }
714 }
717 }
719 /* A wrapper for fold_negate_expr_1. */
721 static tree
723 {
730 }
732 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
733 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
734 return NULL_TREE. */
736 static tree
738 {
740 location_t loc;
753 }
754 \f
755 /* Split a tree IN into a constant, literal and variable parts that could be
756 combined with CODE to make IN. "constant" means an expression with
757 TREE_CONSTANT but that isn't an actual constant. CODE must be a
758 commutative arithmetic operation. Store the constant part into *CONP,
759 the literal in *LITP and return the variable part. If a part isn't
760 present, set it to null. If the tree does not decompose in this way,
761 return the entire tree as the variable part and the other parts as null.
763 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
764 case, we negate an operand that was subtracted. Except if it is a
765 literal for which we use *MINUS_LITP instead.
767 If NEGATE_P is true, we are negating all of IN, again except a literal
768 for which we use *MINUS_LITP instead. If a variable part is of pointer
769 type, it is negated after converting to TYPE. This prevents us from
770 generating illegal MINUS pointer expression. LOC is the location of
771 the converted variable part.
773 If IN is itself a literal or constant, return it as appropriate.
775 Note that we do not guarantee that any of the three values will be the
776 same type as IN, but they will have the same signedness and mode. */
778 static tree
781 {
788 /* Strip any conversions that don't change the machine mode or signedness. */
797 /* We can associate addition and subtraction together (even
798 though the C standard doesn't say so) for integers because
799 the value is not affected. For reals, the value might be
800 affected, so we can't. */
803 {
809 /* First see if either of the operands is a literal, then a constant. */
822 /* If we haven't dealt with either operand, this is not a case we can
823 decompose. Otherwise, VAR is either of the ones remaining, if any. */
828 else
831 /* Now do any needed negations. */
837 {
838 /* Convert to TYPE before negating. */
841 }
842 }
847 {
848 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
849 when IN is constant. */
852 }
853 else
857 {
864 {
865 /* Convert to TYPE before negating. */
868 }
869 }
872 }
874 /* Re-associate trees split by the above function. T1 and T2 are
875 either expressions to associate or null. Return the new
876 expression, if any. LOC is the location of the new expression. If
877 we build an operation, do it in TYPE and with CODE. */
879 static tree
881 {
887 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
888 try to fold this since we will have infinite recursion. But do
889 deal with any NEGATE_EXPRs. */
892 {
894 {
907 }
909 {
912 }
916 }
920 }
921 \f
922 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
923 for use in int_const_binop, size_binop and size_diffop. */
925 static bool
927 {
934 {
943 }
948 }
951 /* Combine two integer constants ARG1 and ARG2 under operation CODE
952 to produce a new constant. Return NULL_TREE if we don't know how
953 to evaluate CODE at compile-time. */
955 static tree
958 {
959 wide_int res;
960 tree t;
968 {
984 {
988 else
990 }
993 /* It's unclear from the C standard whether shifts can overflow.
994 The following code ignores overflow; perhaps a C standard
995 interpretation ruling is needed. */
997 else
1004 {
1008 else
1010 }
1014 else
1093 }
1101 }
1103 tree
1105 {
1107 }
1109 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1110 constant. We assume ARG1 and ARG2 have the same data type, or at least
1111 are the same kind of constant and the same machine mode. Return zero if
1112 combining the constants is not allowed in the current operating mode. */
1114 static tree
1116 {
1117 /* Sanity check for the recursive cases. */
1125 {
1131 }
1134 {
1135 machine_mode mode;
1136 REAL_VALUE_TYPE d1;
1137 REAL_VALUE_TYPE d2;
1138 REAL_VALUE_TYPE value;
1139 REAL_VALUE_TYPE result;
1143 /* The following codes are handled by real_arithmetic. */
1145 {
1156 }
1164 /* Don't perform operation if we honor signaling NaNs and
1165 either operand is a signaling NaN. */
1171 /* Don't perform operation if it would raise a division
1172 by zero exception. */
1178 /* If either operand is a NaN, just return it. Otherwise, set up
1179 for floating-point trap; we return an overflow. */
1181 {
1182 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1183 is off. */
1187 }
1189 {
1190 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1191 is off. */
1195 }
1200 /* Don't constant fold this floating point operation if
1201 the result has overflowed and flag_trapping_math. */
1209 /* Don't constant fold this floating point operation if the
1210 result may dependent upon the run-time rounding mode and
1211 flag_rounding_math is set, or if GCC's software emulation
1212 is unable to accurately represent the result. */
1222 }
1225 {
1226 FIXED_VALUE_TYPE f1;
1227 FIXED_VALUE_TYPE f2;
1228 FIXED_VALUE_TYPE result;
1233 /* The following codes are handled by fixed_arithmetic. */
1235 {
1247 {
1254 }
1259 }
1266 /* Propagate overflow flags. */
1270 }
1273 {
1282 {
1293 mpc_mul);
1307 mpc_div);
1308 /* Fallthru. */
1314 {
1315 /* Keep this algorithm in sync with
1316 tree-complex.c:expand_complex_div_straight().
1318 Expand complex division to scalars, straightforward algorithm.
1319 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1320 t = br*br + bi*bi
1321 */
1322 tree magsquared
1326 tree t1
1330 tree t2
1337 }
1338 else
1339 {
1340 /* Keep this algorithm in sync with
1341 tree-complex.c:expand_complex_div_wide().
1343 Expand complex division to scalars, modified algorithm to minimize
1344 overflow with wide input ranges. */
1350 {
1351 /* In the TRUE branch, we compute
1352 ratio = br/bi;
1353 div = (br * ratio) + bi;
1354 tr = (ar * ratio) + ai;
1355 ti = (ai * ratio) - ar;
1356 tr = tr / div;
1357 ti = ti / div; */
1368 }
1369 else
1370 {
1371 /* In the FALSE branch, we compute
1372 ratio = d/c;
1373 divisor = (d * ratio) + c;
1374 tr = (b * ratio) + a;
1375 ti = b - (a * ratio);
1376 tr = tr / div;
1377 ti = ti / div; */
1389 }
1390 }
1395 }
1399 }
1403 {
1409 {
1415 /* It is possible that const_binop cannot handle the given
1416 code and return NULL_TREE */
1419 }
1422 }
1424 /* Shifts allow a scalar offset for a vector. */
1427 {
1433 {
1438 /* It is possible that const_binop cannot handle the given
1439 code and return NULL_TREE. */
1442 }
1445 }
1447 }
1449 /* Overload that adds a TYPE parameter to be able to dispatch
1450 to fold_relational_const. */
1452 tree
1454 {
1458 /* ??? Until we make the const_binop worker take the type of the
1459 result as argument put those cases that need it here. */
1461 {
1472 {
1488 {
1494 }
1497 }
1503 {
1528 {
1541 }
1544 }
1547 }
1552 /* Make sure type and arg0 have the same saturating flag. */
1557 }
1559 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1560 Return zero if computing the constants is not possible. */
1562 tree
1564 {
1565 /* Don't perform the operation, other than NEGATE and ABS, if
1566 flag_signaling_nans is on and the operand is a signaling NaN. */
1575 {
1576 CASE_CONVERT:
1583 /* If the source address is 0, and the source address space
1584 cannot have a valid object at 0, fold to dest type null. */
1595 {
1596 /* Can't call fold_negate_const directly here as that doesn't
1597 handle all cases and we might not be able to negate some
1598 constants. */
1603 }
1612 {
1616 }
1622 /* Perform BIT_NOT_EXPR on each element individually. */
1624 {
1626 tree elem;
1631 {
1637 }
1640 }
1662 {
1681 else
1685 {
1689 }
1692 }
1697 {
1711 {
1716 }
1719 {
1723 }
1726 }
1730 }
1733 }
1735 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1736 indicates which particular sizetype to create. */
1738 tree
1740 {
1742 }
1743 \f
1744 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1745 is a tree code. The type of the result is taken from the operands.
1746 Both must be equivalent integer types, ala int_binop_types_match_p.
1747 If the operands are constant, so is the result. */
1749 tree
1751 {
1760 /* Handle the special case of two integer constants faster. */
1762 {
1763 /* And some specific cases even faster than that. */
1765 {
1770 }
1772 {
1775 }
1777 {
1780 }
1782 /* Handle general case of two integer constants. For sizetype
1783 constant calculations we always want to know about overflow,
1784 even in the unsigned case. */
1786 }
1789 }
1791 /* Given two values, either both of sizetype or both of bitsizetype,
1792 compute the difference between the two values. Return the value
1793 in signed type corresponding to the type of the operands. */
1795 tree
1797 {
1799 tree ctype;
1804 /* If the type is already signed, just do the simple thing. */
1812 else
1815 /* If either operand is not a constant, do the conversions to the signed
1816 type and subtract. The hardware will do the right thing with any
1817 overflow in the subtraction. */
1823 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1824 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1825 overflow) and negate (which can't either). Special-case a result
1826 of zero while we're here. */
1832 else
1836 MINUS_EXPR,
1838 }
1839 \f
1840 /* A subroutine of fold_convert_const handling conversions of an
1841 INTEGER_CST to another integer type. */
1843 static tree
1845 {
1846 /* Given an integer constant, make new constant with new type,
1847 appropriately sign-extended or truncated. Use widest_int
1848 so that any extension is done according ARG1's type. */
1852 }
1854 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1855 to an integer type. */
1857 static tree
1859 {
1861 tree t;
1863 /* The following code implements the floating point to integer
1864 conversion rules required by the Java Language Specification,
1865 that IEEE NaNs are mapped to zero and values that overflow
1866 the target precision saturate, i.e. values greater than
1867 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1868 are mapped to INT_MIN. These semantics are allowed by the
1869 C and C++ standards that simply state that the behavior of
1870 FP-to-integer conversion is unspecified upon overflow. */
1872 wide_int val;
1873 REAL_VALUE_TYPE r;
1877 {
1884 }
1886 /* If R is NaN, return zero and show we have an overflow. */
1888 {
1891 }
1893 /* See if R is less than the lower bound or greater than the
1894 upper bound. */
1897 {
1901 {
1904 }
1905 }
1908 {
1911 {
1914 {
1917 }
1918 }
1919 }
1926 }
1928 /* A subroutine of fold_convert_const handling conversions of a
1929 FIXED_CST to an integer type. */
1931 static tree
1933 {
1934 tree t;
1938 /* Right shift FIXED_CST to temp by fbit. */
1942 {
1944 HOST_BITS_PER_DOUBLE_INT,
1947 /* Left shift temp to temp_trunc by fbit. */
1949 HOST_BITS_PER_DOUBLE_INT,
1951 }
1952 else
1953 {
1956 }
1958 /* If FIXED_CST is negative, we need to round the value toward 0.
1959 By checking if the fractional bits are not zero to add 1 to temp. */
1965 /* Given a fixed-point constant, make new constant with new type,
1966 appropriately sign-extended or truncated. */
1974 }
1976 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1977 to another floating point type. */
1979 static tree
1981 {
1982 REAL_VALUE_TYPE value;
1983 tree t;
1985 /* Don't perform the operation if flag_signaling_nans is on
1986 and the operand is a signaling NaN. */
1994 /* If converting an infinity or NAN to a representation that doesn't
1995 have one, set the overflow bit so that we can produce some kind of
1996 error message at the appropriate point if necessary. It's not the
1997 most user-friendly message, but it's better than nothing. */
2004 /* Regular overflow, conversion produced an infinity in a mode that
2005 can't represent them. */
2010 else
2013 }
2015 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2016 to a floating point type. */
2018 static tree
2020 {
2021 REAL_VALUE_TYPE value;
2022 tree t;
2029 }
2031 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2032 to another fixed-point type. */
2034 static tree
2036 {
2037 FIXED_VALUE_TYPE value;
2038 tree t;
2045 /* Propagate overflow flags. */
2049 }
2051 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2052 to a fixed-point type. */
2054 static tree
2056 {
2057 FIXED_VALUE_TYPE value;
2058 tree t;
2060 double_int di;
2067 else
2075 /* Propagate overflow flags. */
2079 }
2081 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2082 to a fixed-point type. */
2084 static tree
2086 {
2087 FIXED_VALUE_TYPE value;
2088 tree t;
2096 /* Propagate overflow flags. */
2100 }
2102 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2103 type TYPE. If no simplification can be done return NULL_TREE. */
2105 static tree
2107 {
2113 {
2120 }
2122 {
2129 }
2131 {
2138 }
2140 {
2143 {
2148 {
2154 }
2156 }
2157 }
2159 }
2161 /* Construct a vector of zero elements of vector type TYPE. */
2163 static tree
2165 {
2166 tree t;
2170 }
2172 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2174 bool
2176 {
2191 {
2206 }
2207 }
2209 /* Convert expression ARG to type TYPE. Used by the middle-end for
2210 simple conversions in preference to calling the front-end's convert. */
2212 tree
2214 {
2216 tree tem;
2227 {
2230 /* Handle conversions between pointers to different address spaces. */
2235 /* fall through */
2240 {
2244 }
2258 {
2262 }
2264 {
2268 }
2270 {
2274 }
2277 {
2295 }
2300 {
2304 }
2307 {
2321 }
2325 {
2334 integer_zero_node));
2336 {
2340 {
2346 }
2354 }
2358 }
2376 }
2377 fold_convert_exit:
2380 }
2381 \f
2382 /* Return false if expr can be assumed not to be an lvalue, true
2383 otherwise. */
2385 static bool
2387 {
2388 /* We only need to wrap lvalue tree codes. */
2390 {
2421 /* Assume the worst for front-end tree codes. */
2425 }
2428 }
2430 /* Return an expr equal to X but certainly not valid as an lvalue. */
2432 tree
2434 {
2435 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2436 us. */
2443 }
2445 /* When pedantic, return an expr equal to X but certainly not valid as a
2446 pedantic lvalue. Otherwise, return X. */
2448 static tree
2450 {
2452 }
2453 \f
2454 /* Given a tree comparison code, return the code that is the logical inverse.
2455 It is generally not safe to do this for floating-point comparisons, except
2456 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2457 ERROR_MARK in this case. */
2459 enum tree_code
2461 {
2467 {
2498 }
2499 }
2501 /* Similar, but return the comparison that results if the operands are
2502 swapped. This is safe for floating-point. */
2504 enum tree_code
2506 {
2508 {
2534 }
2535 }
2538 /* Convert a comparison tree code from an enum tree_code representation
2539 into a compcode bit-based encoding. This function is the inverse of
2540 compcode_to_comparison. */
2542 static enum comparison_code
2544 {
2546 {
2577 }
2578 }
2580 /* Convert a compcode bit-based encoding of a comparison operator back
2581 to GCC's enum tree_code representation. This function is the
2582 inverse of comparison_to_compcode. */
2584 static enum tree_code
2586 {
2588 {
2619 }
2620 }
2622 /* Return a tree for the comparison which is the combination of
2623 doing the AND or OR (depending on CODE) of the two operations LCODE
2624 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2625 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2626 if this makes the transformation invalid. */
2628 tree
2633 {
2640 {
2651 }
2654 {
2655 /* Eliminate unordered comparisons, as well as LTGT and ORD
2656 which are not used unless the mode has NaNs. */
2662 }
2664 {
2665 /* Check that the original operation and the optimized ones will trap
2666 under the same condition. */
2677 /* In a short-circuited boolean expression the LHS might be
2678 such that the RHS, if evaluated, will never trap. For
2679 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2680 if neither x nor y is NaN. (This is a mixed blessing: for
2681 example, the expression above will never trap, hence
2682 optimizing it to x < y would be invalid). */
2687 /* If the comparison was short-circuited, and only the RHS
2688 trapped, we may now generate a spurious trap. */
2693 /* If we changed the conditions that cause a trap, we lose. */
2696 }
2702 else
2703 {
2708 }
2709 }
2710 \f
2711 /* Return nonzero if two operands (typically of the same tree node)
2712 are necessarily equal. FLAGS modifies behavior as follows:
2714 If OEP_ONLY_CONST is set, only return nonzero for constants.
2715 This function tests whether the operands are indistinguishable;
2716 it does not test whether they are equal using C's == operation.
2717 The distinction is important for IEEE floating point, because
2718 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2719 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2721 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2722 even though it may hold multiple values during a function.
2723 This is because a GCC tree node guarantees that nothing else is
2724 executed between the evaluation of its "operands" (which may often
2725 be evaluated in arbitrary order). Hence if the operands themselves
2726 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2727 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2728 unset means assuming isochronic (or instantaneous) tree equivalence.
2729 Unless comparing arbitrary expression trees, such as from different
2730 statements, this flag can usually be left unset.
2732 If OEP_PURE_SAME is set, then pure functions with identical arguments
2733 are considered the same. It is used when the caller has other ways
2734 to ensure that global memory is unchanged in between.
2736 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2737 not values of expressions.
2739 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2740 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2742 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2743 any operand with side effect. This is unnecesarily conservative in the
2744 case we know that arg0 and arg1 are in disjoint code paths (such as in
2745 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2746 addresses with TREE_CONSTANT flag set so we know that &var == &var
2747 even if var is volatile. */
2749 int
2751 {
2752 /* When checking, verify at the outermost operand_equal_p call that
2753 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2754 hash value. */
2756 {
2758 {
2760 {
2767 }
2769 }
2770 else
2772 }
2774 /* If either is ERROR_MARK, they aren't equal. */
2780 /* Similar, if either does not have a type (like a released SSA name),
2781 they aren't equal. */
2785 /* We cannot consider pointers to different address space equal. */
2792 /* Check equality of integer constants before bailing out due to
2793 precision differences. */
2795 {
2796 /* Address of INTEGER_CST is not defined; check that we did not forget
2797 to drop the OEP_ADDRESS_OF flags. */
2800 }
2803 {
2804 /* If both types don't have the same signedness, then we can't consider
2805 them equal. We must check this before the STRIP_NOPS calls
2806 because they may change the signedness of the arguments. As pointers
2807 strictly don't have a signedness, require either two pointers or
2808 two non-pointers as well. */
2814 /* If both types don't have the same precision, then it is not safe
2815 to strip NOPs. */
2822 }
2823 #if 0
2824 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2825 sanity check once the issue is solved. */
2826 else
2827 /* Addresses of conversions and SSA_NAMEs (and many other things)
2828 are not defined. Check that we did not forget to drop the
2829 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2832 #endif
2834 /* In case both args are comparisons but with different comparison
2835 code, try to swap the comparison operands of one arg to produce
2836 a match and compare that variant. */
2840 {
2848 }
2851 {
2852 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2854 ;
2856 {
2857 /* If we are interested in comparing addresses ignore
2858 MEM_REF wrappings of the base that can appear just for
2859 TBAA reasons. */
2873 }
2874 else
2876 }
2878 /* When not checking adddresses, this is needed for conversions and for
2879 COMPONENT_REF. Might as well play it safe and always test this. */
2886 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2887 We don't care about side effects in that case because the SAVE_EXPR
2888 takes care of that for us. In all other cases, two expressions are
2889 equal if they have no side effects. If we have two identical
2890 expressions with side effects that should be treated the same due
2891 to the only side effects being identical SAVE_EXPR's, that will
2892 be detected in the recursive calls below.
2893 If we are taking an invariant address of two identical objects
2894 they are necessarily equal as well. */
2901 /* Next handle constant cases, those for which we can return 1 even
2902 if ONLY_CONST is set. */
2905 {
2919 {
2920 /* If we do not distinguish between signed and unsigned zero,
2921 consider them equal. */
2924 }
2928 {
2935 {
2939 }
2941 }
2945 flags)
2947 flags));
2958 flags | OEP_ADDRESS_OF
2961 /* In GIMPLE empty constructors are allowed in initializers of
2962 aggregates. */
2966 }
2971 /* Define macros to test an operand from arg0 and arg1 for equality and a
2972 variant that allows null and views null as being different from any
2973 non-null value. In the latter case, if either is null, the both
2974 must be; otherwise, do the normal comparison. */
2975 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2976 TREE_OPERAND (arg1, N), flags)
2978 #define OP_SAME_WITH_NULL(N) \
2979 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2980 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2983 {
2985 /* Two conversions are equal only if signedness and modes match. */
2987 {
2988 CASE_CONVERT:
2996 }
3006 /* For commutative ops, allow the other order. */
3014 /* If either of the pointer (or reference) expressions we are
3015 dereferencing contain a side effect, these cannot be equal,
3016 but their addresses can be. */
3023 {
3033 /* Require the same offset. */
3039 /* Fallthru. */
3047 {
3048 /* Require equal access sizes */
3054 flags)))
3056 /* Verify that access happens in similar types. */
3059 /* Verify that accesses are TBAA compatible. */
3068 /* Verify that alignment is compatible. */
3072 }
3075 /* TARGET_MEM_REF require equal extra operands. */
3086 /* Compare the array index by value if it is constant first as we
3087 may have different types but same value here. */
3093 /* Compare low bound and element size as with OEP_ADDRESS_OF
3094 we have to account for the offset of the ref. */
3099 array_ref_low_bound
3103 array_ref_element_size
3105 flags))));
3108 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3109 may be NULL when we're called to compare MEM_EXPRs. */
3124 }
3128 {
3130 /* Be sure we pass right ADDRESS_OF flag. */
3148 /* The multiplcation operands are commutative. */
3149 /* FALLTHRU */
3157 /* Otherwise take into account this is a commutative operation. */
3193 }
3197 {
3201 /* If not both CALL_EXPRs are either internal or normal function
3202 functions, then they are not equal. */
3205 {
3206 /* If the CALL_EXPRs call different internal functions, then they
3207 are not equal. */
3210 }
3211 else
3212 {
3213 /* If the CALL_EXPRs call different functions, then they are not
3214 equal. */
3216 flags))
3218 }
3220 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3221 {
3225 else
3229 }
3231 /* Now see if all the arguments are the same. */
3232 {
3243 /* If we get here and both argument lists are exhausted
3244 then the CALL_EXPRs are equal. */
3246 }
3249 }
3252 /* Consider __builtin_sqrt equal to sqrt. */
3260 {
3261 /* In GIMPLE constructors are used only to build vectors from
3262 elements. Individual elements in the constructor must be
3263 indexed in increasing order and form an initial sequence.
3265 We make no effort to compare constructors in generic.
3266 (see sem_variable::equals in ipa-icf which can do so for
3267 constants). */
3272 /* Be sure that vectors constructed have the same representation.
3273 We only tested element precision and modes to match.
3274 Vectors may be BLKmode and thus also check that the number of
3275 parts match. */
3288 {
3293 /* In GIMPLE the indexes can be either NULL or matching i.
3294 Double check this so we won't get false
3295 positives for GENERIC. */
3303 }
3305 }
3308 {
3309 /* Compare the STATEMENT_LISTs. */
3315 {
3316 /* The lists don't have the same number of statements. */
3322 OEP_LEXICOGRAPHIC))
3324 }
3325 }
3330 {
3337 }
3341 }
3343 #undef OP_SAME
3344 #undef OP_SAME_WITH_NULL
3345 }
3346 \f
3347 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3348 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3350 When in doubt, return 0. */
3352 static int
3354 {
3366 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3367 and see if the inner values are the same. This removes any
3368 signedness comparison, which doesn't matter here. */
3375 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3376 actual comparison operand, ARG0.
3378 First throw away any conversions to wider types
3379 already present in the operands. */
3388 {
3391 /* Make sure shorter operand is extended the right way
3392 to match the longer operand. */
3398 }
3401 }
3402 \f
3403 /* See if ARG is an expression that is either a comparison or is performing
3404 arithmetic on comparisons. The comparisons must only be comparing
3405 two different values, which will be stored in *CVAL1 and *CVAL2; if
3406 they are nonzero it means that some operands have already been found.
3407 No variables may be used anywhere else in the expression except in the
3408 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3409 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3411 If this is true, return 1. Otherwise, return zero. */
3413 static int
3415 {
3419 /* We can handle some of the tcc_expression cases here. */
3429 {
3430 /* If we've already found a CVAL1 or CVAL2, this expression is
3431 two complex to handle. */
3437 }
3440 {
3463 /* First see if we can handle the first operand, then the second. For
3464 the second operand, we know *CVAL1 can't be zero. It must be that
3465 one side of the comparison is each of the values; test for the
3466 case where this isn't true by failing if the two operands
3467 are the same. */
3476 ;
3480 ;
3481 else
3485 ;
3489 ;
3490 else
3497 }
3498 }
3499 \f
3500 /* ARG is a tree that is known to contain just arithmetic operations and
3501 comparisons. Evaluate the operations in the tree substituting NEW0 for
3502 any occurrence of OLD0 as an operand of a comparison and likewise for
3503 NEW1 and OLD1. */
3505 static tree
3508 {
3513 /* We can handle some of the tcc_expression cases here. */
3521 {
3536 {
3555 }
3556 /* Fall through - ??? */
3559 {
3563 /* We need to check both for exact equality and tree equality. The
3564 former will be true if the operand has a side-effect. In that
3565 case, we know the operand occurred exactly once. */
3578 }
3582 }
3583 }
3584 \f
3585 /* Return a tree for the case when the result of an expression is RESULT
3586 converted to TYPE and OMITTED was previously an operand of the expression
3587 but is now not needed (e.g., we folded OMITTED * 0).
3589 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3590 the conversion of RESULT to TYPE. */
3592 tree
3594 {
3597 /* If the resulting operand is an empty statement, just return the omitted
3598 statement casted to void. */
3608 }
3610 /* Return a tree for the case when the result of an expression is RESULT
3611 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3612 of the expression but are now not needed.
3614 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3615 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3616 evaluated before OMITTED2. Otherwise, if neither has side effects,
3617 just do the conversion of RESULT to TYPE. */
3619 tree
3622 {
3631 }
3633 \f
3634 /* Return a simplified tree node for the truth-negation of ARG. This
3635 never alters ARG itself. We assume that ARG is an operation that
3636 returns a truth value (0 or 1).
3638 FIXME: one would think we would fold the result, but it causes
3639 problems with the dominator optimizer. */
3641 static tree
3643 {
3648 /* If this is a comparison, we can simply invert it, except for
3649 floating-point non-equality comparisons, in which case we just
3650 enclose a TRUTH_NOT_EXPR around what we have. */
3653 {
3656 && flag_trapping_math
3670 }
3673 {
3692 /* Here we can invert either operand. We invert the first operand
3693 unless the second operand is a TRUTH_NOT_EXPR in which case our
3694 result is the XOR of the first operand with the inside of the
3695 negation of the second operand. */
3700 else
3723 {
3730 /* A COND_EXPR may have a throw as one operand, which
3731 then has void type. Just leave void operands
3732 as they are. */
3738 }
3750 CASE_CONVERT:
3754 /* fall through */
3776 }
3777 }
3779 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3780 assume that ARG is an operation that returns a truth value (0 or 1
3781 for scalars, 0 or -1 for vectors). Return the folded expression if
3782 folding is successful. Otherwise, return NULL_TREE. */
3784 static tree
3786 {
3789 ? BIT_NOT_EXPR
3792 }
3794 /* Return a simplified tree node for the truth-negation of ARG. This
3795 never alters ARG itself. We assume that ARG is an operation that
3796 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3798 tree
3800 {
3806 ? BIT_NOT_EXPR
3809 }
3811 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3812 with code CODE. This optimization is unsafe. */
3813 static tree
3816 {
3820 /* (A / C) +- (B / C) -> (A +- B) / C. */
3830 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3835 {
3847 }
3850 }
3851 \f
3852 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3853 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3854 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3855 is the original memory reference used to preserve the alias set of
3856 the access. */
3858 static tree
3862 {
3872 {
3879 }
3894 }
3896 /* Optimize a bit-field compare.
3898 There are two cases: First is a compare against a constant and the
3899 second is a comparison of two items where the fields are at the same
3900 bit position relative to the start of a chunk (byte, halfword, word)
3901 large enough to contain it. In these cases we can avoid the shift
3902 implicit in bitfield extractions.
3904 For constants, we emit a compare of the shifted constant with the
3905 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3906 compared. For two fields at the same position, we do the ANDs with the
3907 similar mask and compare the result of the ANDs.
3909 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3910 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3911 are the left and right operands of the comparison, respectively.
3913 If the optimization described above can be done, we return the resulting
3914 tree. Otherwise we return zero. */
3916 static tree
3919 {
3922 tree unsigned_type;
3929 tree mask;
3930 tree offset;
3932 /* Get all the information about the extractions being done. If the bit size
3933 if the same as the size of the underlying object, we aren't doing an
3934 extraction at all and so can do nothing. We also don't want to
3935 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3936 then will no longer be able to replace it. */
3945 else
3946 {
3947 /* If this is not a constant, we can only do something if bit positions,
3948 sizes, signedness and storage order are the same. */
3949 rinner
3957 }
3959 /* Honor the C++ memory model and mimic what RTL expansion does. */
3963 {
3967 }
3969 /* See if we can find a mode to refer to this field. We should be able to,
3970 but fail if we can't. */
3979 /* Set signed and unsigned types of the precision of this mode for the
3980 shifts below. */
3983 /* Compute the bit position and size for the new reference and our offset
3984 within it. If the new reference is the same size as the original, we
3985 won't optimize anything, so return zero. */
3995 /* Make the mask to be used against the extracted field. */
4002 /* If not comparing with constant, just rework the comparison
4003 and return. */
4007 unsigned_type,
4010 mask),
4013 unsigned_type,
4016 mask));
4018 /* Otherwise, we are handling the constant case. See if the constant is too
4019 big for the field. Warn and return a tree for 0 (false) if so. We do
4020 this not only for its own sake, but to avoid having to test for this
4021 error case below. If we didn't, we might generate wrong code.
4023 For unsigned fields, the constant shifted right by the field length should
4024 be all zero. For signed fields, the high-order bits should agree with
4025 the sign bit. */
4028 {
4030 {
4034 }
4035 }
4036 else
4037 {
4040 {
4044 }
4045 }
4047 /* Single-bit compares should always be against zero. */
4049 {
4052 }
4054 /* Make a new bitfield reference, shift the constant over the
4055 appropriate number of bits and mask it with the computed mask
4056 (in case this was a signed field). If we changed it, make a new one. */
4064 mask);
4069 }
4070 \f
4071 /* Subroutine for fold_truth_andor_1: decode a field reference.
4073 If EXP is a comparison reference, we return the innermost reference.
4075 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4076 set to the starting bit number.
4078 If the innermost field can be completely contained in a mode-sized
4079 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4081 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4082 otherwise it is not changed.
4084 *PUNSIGNEDP is set to the signedness of the field.
4086 *PREVERSEP is set to the storage order of the field.
4088 *PMASK is set to the mask used. This is either contained in a
4089 BIT_AND_EXPR or derived from the width of the field.
4091 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4093 Return 0 if this is not a component reference or is one that we can't
4094 do anything with. */
4096 static tree
4101 {
4106 tree unsigned_type;
4109 /* All the optimizations using this function assume integer fields.
4110 There are problems with FP fields since the type_for_size call
4111 below can fail for, e.g., XFmode. */
4115 /* We are interested in the bare arrangement of bits, so strip everything
4116 that doesn't affect the machine mode. However, record the type of the
4117 outermost expression if it may matter below. */
4124 {
4130 }
4141 /* If the number of bits in the reference is the same as the bitsize of
4142 the outer type, then the outer type gives the signedness. Otherwise
4143 (in case of a small bitfield) the signedness is unchanged. */
4147 /* Compute the mask to access the bitfield. */
4156 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4164 }
4166 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4167 bit positions and MASK is SIGNED. */
4169 static int
4171 {
4175 /* If this function returns true when the type of the mask is
4176 UNSIGNED, then there will be errors. In particular see
4177 gcc.c-torture/execute/990326-1.c. There does not appear to be
4178 any documentation paper trail as to why this is so. But the pre
4179 wide-int worked with that restriction and it has been preserved
4180 here. */
4185 }
4187 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4188 represents the sign bit of EXP's type. If EXP represents a sign
4189 or zero extension, also test VAL against the unextended type.
4190 The return value is the (sub)expression whose sign bit is VAL,
4191 or NULL_TREE otherwise. */
4193 tree
4195 {
4197 tree t;
4199 /* Tree EXP must have an integral type. */
4204 /* Tree VAL must be an integer constant. */
4213 /* Handle extension from a narrower type. */
4219 }
4221 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4222 to be evaluated unconditionally. */
4224 static int
4226 {
4227 /* Strip any conversions that don't change the machine mode. */
4236 /* Don't regard global variables as simple. They may be
4237 allocated in ways unknown to the compiler (shared memory,
4238 #pragma weak, etc). */
4241 /* Weakrefs are not safe to be read, since they can be NULL.
4242 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4243 have DECL_WEAK flag set. */
4245 /* Loading a static variable is unduly expensive, but global
4246 registers aren't expensive. */
4248 }
4250 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4251 to be evaluated unconditionally.
4252 I addition to simple_operand_p, we assume that comparisons, conversions,
4253 and logic-not operations are simple, if their operands are simple, too. */
4255 static bool
4257 {
4277 }
4279 \f
4280 /* The following functions are subroutines to fold_range_test and allow it to
4281 try to change a logical combination of comparisons into a range test.
4283 For example, both
4284 X == 2 || X == 3 || X == 4 || X == 5
4285 and
4286 X >= 2 && X <= 5
4287 are converted to
4288 (unsigned) (X - 2) <= 3
4290 We describe each set of comparisons as being either inside or outside
4291 a range, using a variable named like IN_P, and then describe the
4292 range with a lower and upper bound. If one of the bounds is omitted,
4293 it represents either the highest or lowest value of the type.
4295 In the comments below, we represent a range by two numbers in brackets
4296 preceded by a "+" to designate being inside that range, or a "-" to
4297 designate being outside that range, so the condition can be inverted by
4298 flipping the prefix. An omitted bound is represented by a "-". For
4299 example, "- [-, 10]" means being outside the range starting at the lowest
4300 possible value and ending at 10, in other words, being greater than 10.
4301 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4302 always false.
4304 We set up things so that the missing bounds are handled in a consistent
4305 manner so neither a missing bound nor "true" and "false" need to be
4306 handled using a special case. */
4308 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4309 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4310 and UPPER1_P are nonzero if the respective argument is an upper bound
4311 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4312 must be specified for a comparison. ARG1 will be converted to ARG0's
4313 type if both are specified. */
4315 static tree
4318 {
4319 tree tem;
4323 /* If neither arg represents infinity, do the normal operation.
4324 Else, if not a comparison, return infinity. Else handle the special
4325 comparison rules. Note that most of the cases below won't occur, but
4326 are handled for consistency. */
4329 {
4334 }
4339 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4340 for neither. In real maths, we cannot assume open ended ranges are
4341 the same. But, this is computer arithmetic, where numbers are finite.
4342 We can therefore make the transformation of any unbounded range with
4343 the value Z, Z being greater than any representable number. This permits
4344 us to treat unbounded ranges as equal. */
4348 {
4369 }
4372 }
4373 \f
4374 /* Helper routine for make_range. Perform one step for it, return
4375 new expression if the loop should continue or NULL_TREE if it should
4376 stop. */
4378 tree
4382 {
4388 {
4390 /* We can only do something if the range is testing for zero. */
4399 /* We can only do something if the range is testing for zero
4400 and if the second operand is an integer constant. Note that
4401 saying something is "in" the range we make is done by
4402 complementing IN_P since it will set in the initial case of
4403 being not equal to zero; "out" is leaving it alone. */
4410 {
4431 }
4433 /* If this is an unsigned comparison, we also know that EXP is
4434 greater than or equal to zero. We base the range tests we make
4435 on that fact, so we record it here so we can parse existing
4436 range tests. We test arg0_type since often the return type
4437 of, e.g. EQ_EXPR, is boolean. */
4439 {
4443 NULL_TREE))
4448 /* If the high bound is missing, but we have a nonzero low
4449 bound, reverse the range so it goes from zero to the low bound
4450 minus 1. */
4452 {
4457 }
4458 }
4466 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4467 low and high are non-NULL, then normalize will DTRT. */
4470 {
4475 }
4477 /* (-x) IN [a,b] -> x in [-b, -a] */
4489 /* ~ X -> -X - 1 */
4498 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4499 move a constant to the other side. */
4504 /* If EXP is signed, any overflow in the computation is undefined,
4505 so we don't worry about it so long as our computations on
4506 the bounds don't overflow. For unsigned, overflow is defined
4507 and this is exactly the right thing. */
4519 normalize:
4520 /* Check for an unsigned range which has wrapped around the maximum
4521 value thus making n_high < n_low, and normalize it. */
4523 {
4529 /* If the range is of the form +/- [ x+1, x ], we won't
4530 be able to normalize it. But then, it represents the
4531 whole range or the empty set, so make it
4532 +/- [ -, - ]. */
4536 else
4538 }
4539 else
4547 CASE_CONVERT:
4565 /* If we're converting arg0 from an unsigned type, to exp,
4566 a signed type, we will be doing the comparison as unsigned.
4567 The tests above have already verified that LOW and HIGH
4568 are both positive.
4570 So we have to ensure that we will handle large unsigned
4571 values the same way that the current signed bounds treat
4572 negative values. */
4575 {
4576 tree high_positive;
4577 tree equiv_type;
4578 /* For fixed-point modes, we need to pass the saturating flag
4579 as the 2nd parameter. */
4581 equiv_type
4584 else
4585 equiv_type
4588 /* A range without an upper bound is, naturally, unbounded.
4589 Since convert would have cropped a very large value, use
4590 the max value for the destination type. */
4591 high_positive
4598 high_positive),
4601 /* If the low bound is specified, "and" the range with the
4602 range for which the original unsigned value will be
4603 positive. */
4605 {
4608 integer_zero_node),
4609 high_positive))
4613 }
4614 else
4615 {
4616 /* Otherwise, "or" the range with the range of the input
4617 that will be interpreted as negative. */
4620 integer_zero_node),
4621 high_positive))
4625 }
4626 }
4635 }
4636 }
4638 /* Given EXP, a logical expression, set the range it is testing into
4639 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4640 actually being tested. *PLOW and *PHIGH will be made of the same
4641 type as the returned expression. If EXP is not a comparison, we
4642 will most likely not be returning a useful value and range. Set
4643 *STRICT_OVERFLOW_P to true if the return value is only valid
4644 because signed overflow is undefined; otherwise, do not change
4645 *STRICT_OVERFLOW_P. */
4647 tree
4650 {
4658 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4659 and see if we can refine the range. Some of the cases below may not
4660 happen, but it doesn't seem worth worrying about this. We "continue"
4661 the outer loop when we've changed something; otherwise we "break"
4662 the switch, which will "break" the while. */
4668 {
4674 {
4682 }
4691 }
4693 /* If EXP is a constant, we can evaluate whether this is true or false. */
4695 {
4702 }
4706 }
4707 \f
4708 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4709 type, TYPE, return an expression to test if EXP is in (or out of, depending
4710 on IN_P) the range. Return 0 if the test couldn't be created. */
4712 tree
4715 {
4718 /* Disable this optimization for function pointer expressions
4719 on targets that require function pointer canonicalization. */
4726 {
4732 }
4750 {
4752 {
4756 }
4758 }
4760 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4762 {
4766 {
4768 {
4771 etype
4773 else
4776 }
4779 }
4780 }
4782 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4783 This requires wrap-around arithmetics for the type of the expression.
4784 First make sure that arithmetics in this type is valid, then make sure
4785 that it wraps around. */
4791 {
4794 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4795 for the type in question, as we rely on this here. */
4805 else
4807 }
4817 {
4819 {
4824 }
4826 }
4834 }
4835 \f
4836 /* Return the predecessor of VAL in its type, handling the infinite case. */
4838 static tree
4840 {
4846 else
4849 }
4851 /* Return the successor of VAL in its type, handling the infinite case. */
4853 static tree
4855 {
4861 else
4864 }
4866 /* Given two ranges, see if we can merge them into one. Return 1 if we
4867 can, 0 if we can't. Set the output range into the specified parameters. */
4869 bool
4872 {
4876 tree tem;
4886 /* Make range 0 be the range that starts first, or ends last if they
4887 start at the same value. Swap them if it isn't. */
4890 || (lowequal
4893 {
4897 }
4899 /* Now flag two cases, whether the ranges are disjoint or whether the
4900 second range is totally subsumed in the first. Note that the tests
4901 below are simplified by the ones above. */
4907 /* We now have four cases, depending on whether we are including or
4908 excluding the two ranges. */
4910 {
4911 /* If they don't overlap, the result is false. If the second range
4912 is a subset it is the result. Otherwise, the range is from the start
4913 of the second to the end of the first. */
4918 else
4920 }
4923 {
4924 /* If they don't overlap, the result is the first range. If they are
4925 equal, the result is false. If the second range is a subset of the
4926 first, and the ranges begin at the same place, we go from just after
4927 the end of the second range to the end of the first. If the second
4928 range is not a subset of the first, or if it is a subset and both
4929 ranges end at the same place, the range starts at the start of the
4930 first range and ends just before the second range.
4931 Otherwise, we can't describe this as a single range. */
4937 {
4942 {
4943 /* We are in the weird situation where high0 > high1 but
4944 high1 has no successor. Punt. */
4946 }
4947 }
4949 {
4954 {
4955 /* low0 < low1 but low1 has no predecessor. Punt. */
4957 }
4958 }
4959 else
4961 }
4964 {
4965 /* If they don't overlap, the result is the second range. If the second
4966 is a subset of the first, the result is false. Otherwise,
4967 the range starts just after the first range and ends at the
4968 end of the second. */
4973 else
4974 {
4979 {
4980 /* high1 > high0 but high0 has no successor. Punt. */
4982 }
4983 }
4984 }
4986 else
4987 {
4988 /* The case where we are excluding both ranges. Here the complex case
4989 is if they don't overlap. In that case, the only time we have a
4990 range is if they are adjacent. If the second is a subset of the
4991 first, the result is the first. Otherwise, the range to exclude
4992 starts at the beginning of the first range and ends at the end of the
4993 second. */
4995 {
5000 else
5001 {
5002 /* Canonicalize - [min, x] into - [-, x]. */
5005 {
5010 /* FALLTHROUGH */
5023 }
5025 /* Canonicalize - [x, max] into - [x, -]. */
5028 {
5033 /* FALLTHROUGH */
5049 }
5051 /* The ranges might be also adjacent between the maximum and
5052 minimum values of the given type. For
5053 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5054 return + [x + 1, y - 1]. */
5056 {
5063 }
5064 else
5066 }
5067 }
5070 else
5072 }
5076 }
5077 \f
5079 /* Subroutine of fold, looking inside expressions of the form
5080 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5081 of the COND_EXPR. This function is being used also to optimize
5082 A op B ? C : A, by reversing the comparison first.
5084 Return a folded expression whose code is not a COND_EXPR
5085 anymore, or NULL_TREE if no folding opportunity is found. */
5087 static tree
5090 {
5095 tree tem;
5100 /* If we have A op 0 ? A : -A, consider applying the following
5101 transformations:
5103 A == 0? A : -A same as -A
5104 A != 0? A : -A same as A
5105 A >= 0? A : -A same as abs (A)
5106 A > 0? A : -A same as abs (A)
5107 A <= 0? A : -A same as -abs (A)
5108 A < 0? A : -A same as -abs (A)
5110 None of these transformations work for modes with signed
5111 zeros. If A is +/-0, the first two transformations will
5112 change the sign of the result (from +0 to -0, or vice
5113 versa). The last four will fix the sign of the result,
5114 even though the original expressions could be positive or
5115 negative, depending on the sign of A.
5117 Note that all these transformations are correct if A is
5118 NaN, since the two alternatives (A and -A) are also NaNs. */
5125 /* In the case that A is of the form X-Y, '-A' (arg2) may
5126 have already been folded to Y-X, check for that. */
5134 {
5146 /* Fall through. */
5157 /* FALLTHRU */
5167 }
5169 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5170 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5171 both transformations are correct when A is NaN: A != 0
5172 is then true, and A == 0 is false. */
5176 {
5181 }
5183 /* Try some transformations of A op B ? A : B.
5185 A == B? A : B same as B
5186 A != B? A : B same as A
5187 A >= B? A : B same as max (A, B)
5188 A > B? A : B same as max (B, A)
5189 A <= B? A : B same as min (A, B)
5190 A < B? A : B same as min (B, A)
5192 As above, these transformations don't work in the presence
5193 of signed zeros. For example, if A and B are zeros of
5194 opposite sign, the first two transformations will change
5195 the sign of the result. In the last four, the original
5196 expressions give different results for (A=+0, B=-0) and
5197 (A=-0, B=+0), but the transformed expressions do not.
5199 The first two transformations are correct if either A or B
5200 is a NaN. In the first transformation, the condition will
5201 be false, and B will indeed be chosen. In the case of the
5202 second transformation, the condition A != B will be true,
5203 and A will be chosen.
5205 The conversions to max() and min() are not correct if B is
5206 a number and A is not. The conditions in the original
5207 expressions will be false, so all four give B. The min()
5208 and max() versions would give a NaN instead. */
5211 /* Avoid these transformations if the COND_EXPR may be used
5212 as an lvalue in the C++ front-end. PR c++/19199. */
5213 && (in_gimple_form
5219 {
5225 {
5234 /* In C++ a ?: expression can be an lvalue, so put the
5235 operand which will be used if they are equal first
5236 so that we can convert this back to the
5237 corresponding COND_EXPR. */
5239 {
5247 }
5254 {
5262 }
5275 }
5276 }
5279 }
5282 \f
5283 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5284 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5285 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5286 false) >= 2)
5287 #endif
5289 /* EXP is some logical combination of boolean tests. See if we can
5290 merge it into some range test. Return the new tree if so. */
5292 static tree
5295 {
5311 /* If this is an OR operation, invert both sides; we will invert
5312 again at the end. */
5316 /* If both expressions are the same, if we can merge the ranges, and we
5317 can build the range test, return it or it inverted. If one of the
5318 ranges is always true or always false, consider it to be the same
5319 expression as the other. */
5327 {
5331 }
5333 /* On machines where the branch cost is expensive, if this is a
5334 short-circuited branch and the underlying object on both sides
5335 is the same, make a non-short-circuit operation. */
5341 {
5342 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5343 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5344 which cases we can't do this. */
5352 {
5361 {
5364 WARN_STRICT_OVERFLOW_COMPARISON);
5368 }
5369 }
5370 }
5373 }
5374 \f
5375 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5376 bit value. Arrange things so the extra bits will be set to zero if and
5377 only if C is signed-extended to its full width. If MASK is nonzero,
5378 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5380 static tree
5382 {
5385 tree temp;
5390 /* We work by getting just the sign bit into the low-order bit, then
5391 into the high-order bit, then sign-extend. We then XOR that value
5392 with C. */
5395 /* We must use a signed type in order to get an arithmetic right shift.
5396 However, we must also avoid introducing accidental overflows, so that
5397 a subsequent call to integer_zerop will work. Hence we must
5398 do the type conversion here. At this point, the constant is either
5399 zero or one, and the conversion to a signed type can never overflow.
5400 We could get an overflow if this conversion is done anywhere else. */
5409 /* If necessary, convert the type back to match the type of C. */
5414 }
5415 \f
5416 /* For an expression that has the form
5417 (A && B) || ~B
5418 or
5419 (A || B) && ~B,
5420 we can drop one of the inner expressions and simplify to
5421 A || ~B
5422 or
5423 A && ~B
5424 LOC is the location of the resulting expression. OP is the inner
5425 logical operation; the left-hand side in the examples above, while CMPOP
5426 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5427 removing a condition that guards another, as in
5428 (A != NULL && A->...) || A == NULL
5429 which we must not transform. If RHS_ONLY is true, only eliminate the
5430 right-most operand of the inner logical operation. */
5432 static tree
5435 {
5453 {
5456 {
5459 }
5460 }
5462 {
5465 {
5468 }
5469 }
5484 }
5486 /* Find ways of folding logical expressions of LHS and RHS:
5487 Try to merge two comparisons to the same innermost item.
5488 Look for range tests like "ch >= '0' && ch <= '9'".
5489 Look for combinations of simple terms on machines with expensive branches
5490 and evaluate the RHS unconditionally.
5492 For example, if we have p->a == 2 && p->b == 4 and we can make an
5493 object large enough to span both A and B, we can do this with a comparison
5494 against the object ANDed with the a mask.
5496 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5497 operations to do this with one comparison.
5499 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5500 function and the one above.
5502 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5503 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5505 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5506 two operands.
5508 We return the simplified tree or 0 if no optimization is possible. */
5510 static tree
5513 {
5514 /* If this is the "or" of two comparisons, we can do something if
5515 the comparisons are NE_EXPR. If this is the "and", we can do something
5516 if the comparisons are EQ_EXPR. I.e.,
5517 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5519 WANTED_CODE is this operation code. For single bit fields, we can
5520 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5521 comparison for one-bit fields. */
5542 /* Start by getting the comparison codes. Fail if anything is volatile.
5543 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5544 it were surrounded with a NE_EXPR. */
5553 {
5557 }
5560 {
5564 }
5575 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5578 {
5581 {
5586 }
5589 {
5595 }
5596 }
5601 /* If the RHS can be evaluated unconditionally and its operands are
5602 simple, it wins to evaluate the RHS unconditionally on machines
5603 with expensive branches. In this case, this isn't a comparison
5604 that can be merged. */
5611 {
5612 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5623 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5633 }
5635 /* See if the comparisons can be merged. Then get all the parameters for
5636 each side. */
5661 /* It must be true that the inner operation on the lhs of each
5662 comparison must be the same if we are to be able to do anything.
5663 Then see if we have constants. If not, the same must be true for
5664 the rhs's. */
5673 {
5676 }
5681 else
5684 /* If either comparison code is not correct for our logical operation,
5685 fail. However, we can convert a one-bit comparison against zero into
5686 the opposite comparison against that bit being set in the field. */
5690 {
5692 {
5693 /* Make the left operand unsigned, since we are only interested
5694 in the value of one bit. Otherwise we are doing the wrong
5695 thing below. */
5698 }
5699 else
5701 }
5703 /* This is analogous to the code for l_const above. */
5705 {
5707 {
5710 }
5711 else
5713 }
5715 /* See if we can find a mode that contains both fields being compared on
5716 the left. If we can't, fail. Otherwise, update all constants and masks
5717 to be relative to a field of that size. */
5722 volatilep);
5732 {
5735 }
5743 {
5750 {
5754 }
5755 }
5757 {
5764 {
5768 }
5769 }
5771 /* If the right sides are not constant, do the same for it. Also,
5772 disallow this optimization if a size or signedness mismatch occurs
5773 between the left and right sides. */
5775 {
5778 /* Make sure the two fields on the right
5779 correspond to the left without being swapped. */
5787 volatilep);
5797 {
5800 }
5809 /* Make a mask that corresponds to both fields being compared.
5810 Do this for both items being compared. If the operands are the
5811 same size and the bits being compared are in the same position
5812 then we can do this by masking both and comparing the masked
5813 results. */
5817 {
5831 }
5833 /* There is still another way we can do something: If both pairs of
5834 fields being compared are adjacent, we may be able to make a wider
5835 field containing them both.
5837 Note that we still must mask the lhs/rhs expressions. Furthermore,
5838 the mask must be shifted to account for the shift done by
5839 make_bit_field_ref. */
5844 {
5845 tree type;
5861 /* Convert to the smaller type before masking out unwanted bits. */
5864 {
5866 {
5870 }
5872 {
5876 }
5877 }
5886 }
5889 }
5891 /* Handle the case of comparisons with constants. If there is something in
5892 common between the masks, those bits of the constants must be the same.
5893 If not, the condition is always false. Test for this to avoid generating
5894 incorrect code below. */
5899 {
5901 {
5904 }
5905 else
5906 {
5909 }
5910 }
5912 /* Construct the expression we will return. First get the component
5913 reference we will make. Unless the mask is all ones the width of
5914 that field, perform the mask operation. Then compare with the
5915 merged constant. */
5926 }
5927 \f
5928 /* T is an integer expression that is being multiplied, divided, or taken a
5929 modulus (CODE says which and what kind of divide or modulus) by a
5930 constant C. See if we can eliminate that operation by folding it with
5931 other operations already in T. WIDE_TYPE, if non-null, is a type that
5932 should be used for the computation if wider than our type.
5934 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5935 (X * 2) + (Y * 4). We must, however, be assured that either the original
5936 expression would not overflow or that overflow is undefined for the type
5937 in the language in question.
5939 If we return a non-null expression, it is an equivalent form of the
5940 original computation, but need not be in the original type.
5942 We set *STRICT_OVERFLOW_P to true if the return values depends on
5943 signed overflow being undefined. Otherwise we do not change
5944 *STRICT_OVERFLOW_P. */
5946 static tree
5949 {
5950 /* To avoid exponential search depth, refuse to allow recursion past
5951 three levels. Beyond that (1) it's highly unlikely that we'll find
5952 something interesting and (2) we've probably processed it before
5953 when we built the inner expression. */
5956 tree ret;
5961 depth++;
5963 depth--;
5966 }
5968 static tree
5971 {
5982 /* Don't deal with constants of zero here; they confuse the code below. */
5992 /* Note that we need not handle conditional operations here since fold
5993 already handles those cases. So just do arithmetic here. */
5995 {
5997 /* For a constant, we can always simplify if we are a multiply
5998 or (for divide and modulus) if it is a multiple of our constant. */
6001 {
6004 /* If the multiplication overflowed, we lost information on it.
6005 See PR68142 and PR69845. */
6009 }
6013 /* If op0 is an expression ... */
6019 /* ... and has wrapping overflow, and its type is smaller
6020 than ctype, then we cannot pass through as widening. */
6025 /* ... or this is a truncation (t is narrower than op0),
6026 then we cannot pass through this narrowing. */
6029 /* ... or signedness changes for division or modulus,
6030 then we cannot pass through this conversion. */
6034 /* ... or has undefined overflow while the converted to
6035 type has not, we cannot do the operation in the inner type
6036 as that would introduce undefined overflow. */
6042 /* Pass the constant down and see if we can make a simplification. If
6043 we can, replace this expression with the inner simplification for
6044 possible later conversion to our or some other type. */
6049 code == MULT_EXPR
6051 strict_overflow_p))))
6056 /* If widening the type changes it from signed to unsigned, then we
6057 must avoid building ABS_EXPR itself as unsigned. */
6059 {
6063 {
6066 }
6068 }
6069 /* If the constant is negative, we cannot simplify this. */
6072 /* FALLTHROUGH */
6074 /* For division and modulus, type can't be unsigned, as e.g.
6075 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6076 For signed types, even with wrapping overflow, this is fine. */
6085 /* If widening the type changes the signedness, then we can't perform
6086 this optimization as that changes the result. */
6090 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6096 {
6103 }
6107 /* If the second operand is constant, this is a multiplication
6108 or floor division, by a power of two, so we can treat it that
6109 way unless the multiplier or divisor overflows. Signed
6110 left-shift overflow is implementation-defined rather than
6111 undefined in C90, so do not convert signed left shift into
6112 multiplication. */
6115 /* const_binop may not detect overflow correctly,
6116 so check for it explicitly here. */
6120 size_one_node,
6121 op1)))
6125 ctype,
6127 t1),
6132 /* See if we can eliminate the operation on both sides. If we can, we
6133 can return a new PLUS or MINUS. If we can't, the only remaining
6134 cases where we can do anything are if the second operand is a
6135 constant. */
6141 /* If not multiplication, we can only do this if both operands
6142 are divisible by c. */
6145 {
6150 }
6152 /* If this was a subtraction, negate OP1 and set it to be an addition.
6153 This simplifies the logic below. */
6155 {
6157 /* If OP1 was not easily negatable, the constant may be OP0. */
6159 {
6162 }
6163 }
6168 /* If either OP1 or C are negative, this optimization is not safe for
6169 some of the division and remainder types while for others we need
6170 to change the code. */
6172 {
6180 }
6182 /* If it's a multiply or a division/modulus operation of a multiple
6183 of our constant, do the operation and verify it doesn't overflow. */
6186 {
6189 /* We allow the constant to overflow with wrapping semantics. */
6193 }
6194 else
6197 /* If we have an unsigned type, we cannot widen the operation since it
6198 will change the result if the original computation overflowed. */
6202 /* If we were able to eliminate our operation from the first side,
6203 apply our operation to the second side and reform the PLUS. */
6207 /* The last case is if we are a multiply. In that case, we can
6208 apply the distributive law to commute the multiply and addition
6209 if the multiplication of the constants doesn't overflow
6210 and overflow is defined. With undefined overflow
6211 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6217 op1);
6222 /* We have a special case here if we are doing something like
6223 (C * 8) % 4 since we know that's zero. */
6226 /* If the multiplication can overflow we cannot optimize this. */
6230 {
6233 }
6235 /* ... fall through ... */
6239 /* If we can extract our operation from the LHS, do so and return a
6240 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6241 do something only if the second operand is a constant. */
6255 /* If these are the same operation types, we can associate them
6256 assuming no overflow. */
6258 {
6273 }
6275 /* If these operations "cancel" each other, we have the main
6276 optimizations of this pass, which occur when either constant is a
6277 multiple of the other, in which case we replace this with either an
6278 operation or CODE or TCODE.
6280 If we have an unsigned type, we cannot do this since it will change
6281 the result if the original computation overflowed. */
6288 {
6290 {
6297 }
6299 {
6306 }
6307 }
6312 }
6315 }
6316 \f
6317 /* Return a node which has the indicated constant VALUE (either 0 or
6318 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6319 and is of the indicated TYPE. */
6321 tree
6323 {
6332 else
6334 }
6337 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6338 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6339 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6340 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6341 COND is the first argument to CODE; otherwise (as in the example
6342 given here), it is the second argument. TYPE is the type of the
6343 original expression. Return NULL_TREE if no simplification is
6344 possible. */
6346 static tree
6351 {
6361 {
6365 /* If this operand throws an expression, then it does not make
6366 sense to try to perform a logical or arithmetic operation
6367 involving it. */
6372 }
6375 {
6380 }
6381 else
6382 /* Detect the case of mixing vector and scalar types - bail out. */
6388 /* This transformation is only worthwhile if we don't have to wrap ARG
6389 in a SAVE_EXPR and the operation can be simplified without recursing
6390 on at least one of the branches once its pushed inside the COND_EXPR. */
6399 {
6403 else
6405 }
6407 {
6411 else
6413 }
6415 /* Check that we have simplified at least one of the branches. */
6420 }
6422 \f
6423 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6425 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6426 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6427 ADDEND is the same as X.
6429 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6430 and finite. The problematic cases are when X is zero, and its mode
6431 has signed zeros. In the case of rounding towards -infinity,
6432 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6433 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6435 bool
6437 {
6441 /* Don't allow the fold with -fsignaling-nans. */
6445 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6449 /* In a vector or complex, we would need to check the sign of all zeros. */
6453 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6457 /* The mode has signed zeros, and we have to honor their sign.
6458 In this situation, there is only one case we can return true for.
6459 X - 0 is the same as X unless rounding towards -infinity is
6460 supported. */
6462 }
6464 /* Subroutine of fold() that optimizes comparisons of a division by
6465 a nonzero integer constant against an integer constant, i.e.
6466 X/C1 op C2.
6468 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6469 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6470 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6472 The function returns the constant folded tree if a simplification
6473 can be made, and NULL_TREE otherwise. */
6475 static tree
6478 {
6486 /* We have to do this the hard way to detect unsigned overflow.
6487 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6493 {
6498 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6502 }
6504 {
6508 {
6527 }
6528 }
6529 else
6530 {
6531 /* A negative divisor reverses the relational operators. */
6537 {
6556 }
6557 }
6560 {
6581 {
6584 }
6589 {
6592 }
6597 {
6600 }
6605 {
6608 }
6613 }
6616 }
6619 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6620 equality/inequality test, then return a simplified form of the test
6621 using a sign testing. Otherwise return NULL. TYPE is the desired
6622 result type. */
6624 static tree
6627 tree result_type)
6628 {
6629 /* If this is testing a single bit, we can optimize the test. */
6633 {
6634 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6635 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6639 /* This is only a win if casting to a signed type is cheap,
6640 i.e. when arg00's type is not a partial mode. */
6643 {
6646 result_type,
6649 }
6650 }
6653 }
6655 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6656 equality/inequality test, then return a simplified form of
6657 the test using shifts and logical operations. Otherwise return
6658 NULL. TYPE is the desired result type. */
6660 tree
6663 {
6664 /* If this is testing a single bit, we can optimize the test. */
6668 {
6677 /* First, see if we can fold the single bit test into a sign-bit
6678 test. */
6680 result_type);
6684 /* Otherwise we have (A & C) != 0 where C is a single bit,
6685 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6686 Similarly for (A & C) == 0. */
6688 /* If INNER is a right shift of a constant and it plus BITNUM does
6689 not overflow, adjust BITNUM and INNER. */
6695 {
6698 }
6700 /* If we are going to be able to omit the AND below, we must do our
6701 operations as unsigned. If we must use the AND, we have a choice.
6702 Normally unsigned is faster, but for some machines signed is. */
6720 /* Put the AND last so it can combine with more things. */
6723 /* Make sure to return the proper type. */
6727 }
6729 }
6731 /* Test whether it is preferable two swap two operands, ARG0 and
6732 ARG1, for example because ARG0 is an integer constant and ARG1
6733 isn't. */
6735 bool
6737 {
6751 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6752 for commutative and comparison operators. Ensuring a canonical
6753 form allows the optimizers to find additional redundancies without
6754 having to explicitly check for both orderings. */
6760 /* Put SSA_NAMEs last. */
6766 /* Put variables last. */
6773 }
6776 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6777 means A >= Y && A != MAX, but in this case we know that
6778 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6780 static tree
6782 {
6789 else
6798 {
6801 }
6803 {
6806 }
6807 else
6814 {
6815 /* Convert the pointer types into integer before taking the difference. */
6819 }
6820 else
6827 }
6829 /* Fold a sum or difference of at least one multiplication.
6830 Returns the folded tree or NULL if no simplification could be made. */
6832 static tree
6835 {
6839 /* (A * C) +- (B * C) -> (A+-B) * C.
6840 (A * C) +- A -> A * (C+-1).
6841 We are most concerned about the case where C is a constant,
6842 but other combinations show up during loop reduction. Since
6843 it is not difficult, try all four possibilities. */
6846 {
6849 }
6851 {
6854 }
6855 else
6856 {
6857 /* We cannot generate constant 1 for fract. */
6862 }
6864 {
6867 }
6869 {
6871 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6872 the purpose of this canonicalization. */
6876 {
6879 }
6880 else
6882 }
6883 else
6884 {
6885 /* We cannot generate constant 1 for fract. */
6890 }
6902 /* No identical multiplicands; see if we can find a common
6903 power-of-two factor in non-power-of-two multiplies. This
6904 can help in multi-dimensional array access. */
6907 {
6910 tree maybe_same;
6914 /* Move min of absolute values to int11. */
6916 {
6921 }
6922 else
6926 /* The remainder should not be a constant, otherwise we
6927 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6928 increased the number of multiplications necessary. */
6930 {
6938 }
6939 }
6949 }
6951 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6952 specified by EXPR into the buffer PTR of length LEN bytes.
6953 Return the number of bytes placed in the buffer, or zero
6954 upon failure. */
6956 static int
6958 {
6972 {
6974 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
6975 number of bytes. */
6979 {
6986 else
6988 }
6989 else
6994 }
6996 }
6999 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7000 specified by EXPR into the buffer PTR of length LEN bytes.
7001 Return the number of bytes placed in the buffer, or zero
7002 upon failure. */
7004 static int
7006 {
7010 FIXED_VALUE_TYPE value;
7026 }
7029 /* Subroutine of native_encode_expr. Encode the REAL_CST
7030 specified by EXPR into the buffer PTR of length LEN bytes.
7031 Return the number of bytes placed in the buffer, or zero
7032 upon failure. */
7034 static int
7036 {
7042 /* There are always 32 bits in each long, no matter the size of
7043 the hosts long. We handle floating point representations with
7044 up to 192 bits. */
7058 {
7063 {
7070 else
7072 }
7073 else
7074 {
7077 {
7078 /* Reverse bytes within each long, or within the entire float
7079 if it's smaller than a long (for HFmode). */
7082 }
7083 }
7088 }
7090 }
7092 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7093 specified by EXPR into the buffer PTR of length LEN bytes.
7094 Return the number of bytes placed in the buffer, or zero
7095 upon failure. */
7097 static int
7099 {
7101 tree part;
7116 }
7119 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7120 specified by EXPR into the buffer PTR of length LEN bytes.
7121 Return the number of bytes placed in the buffer, or zero
7122 upon failure. */
7124 static int
7126 {
7136 {
7138 {
7141 }
7152 }
7154 }
7157 /* Subroutine of native_encode_expr. Encode the STRING_CST
7158 specified by EXPR into the buffer PTR of length LEN bytes.
7159 Return the number of bytes placed in the buffer, or zero
7160 upon failure. */
7162 static int
7164 {
7166 HOST_WIDE_INT total_bytes;
7180 {
7183 {
7186 }
7189 }
7190 else
7193 }
7196 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7197 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7198 buffer PTR of length LEN bytes. If OFF is not -1 then start
7199 the encoding at byte offset OFF and encode at most LEN bytes.
7200 Return the number of bytes placed in the buffer, or zero upon failure. */
7202 int
7204 {
7205 /* We don't support starting at negative offset and -1 is special. */
7210 {
7231 }
7232 }
7235 /* Subroutine of native_interpret_expr. Interpret the contents of
7236 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7237 If the buffer cannot be interpreted, return NULL_TREE. */
7239 static tree
7241 {
7251 }
7254 /* Subroutine of native_interpret_expr. Interpret the contents of
7255 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7256 If the buffer cannot be interpreted, return NULL_TREE. */
7258 static tree
7260 {
7262 double_int result;
7263 FIXED_VALUE_TYPE fixed_value;
7273 }
7276 /* Subroutine of native_interpret_expr. Interpret the contents of
7277 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7278 If the buffer cannot be interpreted, return NULL_TREE. */
7280 static tree
7282 {
7286 /* There are always 32 bits in each long, no matter the size of
7287 the hosts long. We handle floating point representations with
7288 up to 192 bits. */
7289 REAL_VALUE_TYPE r;
7300 {
7301 /* Both OFFSET and BYTE index within a long;
7302 bitpos indexes the whole float. */
7305 {
7312 else
7314 }
7315 else
7316 {
7319 {
7320 /* Reverse bytes within each long, or within the entire float
7321 if it's smaller than a long (for HFmode). */
7324 }
7325 }
7329 }
7333 }
7336 /* Subroutine of native_interpret_expr. Interpret the contents of
7337 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7338 If the buffer cannot be interpreted, return NULL_TREE. */
7340 static tree
7342 {
7357 }
7360 /* Subroutine of native_interpret_expr. Interpret the contents of
7361 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7362 If the buffer cannot be interpreted, return NULL_TREE. */
7364 static tree
7366 {
7379 {
7384 }
7386 }
7389 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7390 the buffer PTR of length LEN as a constant of type TYPE. For
7391 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7392 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7393 return NULL_TREE. */
7395 tree
7397 {
7399 {
7421 }
7422 }
7424 /* Returns true if we can interpret the contents of a native encoding
7425 as TYPE. */
7427 static bool
7429 {
7431 {
7444 }
7445 }
7447 /* Return true iff a constant of type TYPE is accepted by
7448 native_encode_expr. */
7450 bool
7452 {
7454 {
7464 }
7465 }
7467 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7468 TYPE at compile-time. If we're unable to perform the conversion
7469 return NULL_TREE. */
7471 static tree
7473 {
7474 /* We support up to 512-bit values (for V8DFmode). */
7478 /* Check that the host and target are sane. */
7487 }
7489 /* Build an expression for the address of T. Folds away INDIRECT_REF
7490 to avoid confusing the gimplify process. */
7492 tree
7494 {
7495 /* The size of the object is not relevant when talking about its address. */
7500 {
7505 }
7515 {
7520 }
7521 else
7525 }
7527 /* Build an expression for the address of T. */
7529 tree
7531 {
7535 }
7537 /* Fold a unary expression of code CODE and type TYPE with operand
7538 OP0. Return the folded expression if folding is successful.
7539 Otherwise, return NULL_TREE. */
7541 tree
7543 {
7544 tree tem;
7545 tree arg0;
7553 {
7556 {
7557 /* Don't use STRIP_NOPS, because signedness of argument type
7558 matters. */
7560 }
7561 else
7562 {
7563 /* Strip any conversions that don't change the mode. This
7564 is safe for every expression, except for a comparison
7565 expression because its signedness is derived from its
7566 operands.
7568 Note that this is done as an internal manipulation within
7569 the constant folder, in order to find the simplest
7570 representation of the arguments so that their form can be
7571 studied. In any cases, the appropriate type conversions
7572 should be put back in the tree that will get out of the
7573 constant folder. */
7575 }
7578 {
7581 {
7585 }
7586 }
7587 }
7594 {
7601 {
7615 /* If this was a conversion, and all we did was to move into
7616 inside the COND_EXPR, bring it back out. But leave it if
7617 it is a conversion from integer to integer and the
7618 result precision is no wider than a word since such a
7619 conversion is cheap and may be optimized away by combine,
7620 while it couldn't if it were outside the COND_EXPR. Then return
7621 so we don't get into an infinite recursion loop taking the
7622 conversion out and then back in. */
7634 && (INTEGRAL_TYPE_P
7647 }
7648 }
7651 {
7657 CASE_CONVERT:
7661 {
7662 /* If we have (type) (a CMP b) and type is an integral type, return
7663 new expression involving the new type. Canonicalize
7664 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7665 non-integral type.
7666 Do not fold the result as that would not simplify further, also
7667 folding again results in recursions. */
7677 }
7679 /* Handle (T *)&A.B.C for A being of type T and B and C
7680 living at offset zero. This occurs frequently in
7681 C++ upcasting and then accessing the base. */
7685 {
7687 tree offset;
7688 machine_mode mode;
7690 tree base
7694 /* If the reference was to a (constant) zero offset, we can use
7695 the address of the base if it has the same base type
7696 as the result type and the pointer type is unqualified. */
7703 }
7707 /* Detect assigning a bitfield. */
7709 && DECL_BIT_FIELD
7711 {
7712 /* Don't leave an assignment inside a conversion
7713 unless assigning a bitfield. */
7715 /* First do the assignment, then return converted constant. */
7720 }
7722 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7723 constants (if x has signed type, the sign bit cannot be set
7724 in c). This folds extension into the BIT_AND_EXPR.
7725 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7726 very likely don't have maximal range for their precision and this
7727 transformation effectively doesn't preserve non-maximal ranges. */
7731 {
7742 <= HOST_BITS_PER_WIDE_INT
7744 {
7748 cst &= HOST_WIDE_INT_M1U
7752 && !flag_syntax_only
7755 {
7759 }
7760 }
7762 {
7767 }
7768 }
7770 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7771 cast (T1)X will fold away. We assume that this happens when X itself
7772 is a cast. */
7776 {
7780 return fold_build_pointer_plus_loc
7782 }
7784 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7785 of the same precision, and X is an integer type not narrower than
7786 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7792 {
7798 }
7800 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7801 type of X and Y (integer types only). */
7806 {
7807 /* Be careful not to introduce new overflows. */
7808 tree mult_type;
7811 else
7815 {
7822 }
7823 }
7829 {
7836 }
7847 /* Convert fabs((double)float) into (double)fabsf(float). */
7850 {
7856 targ0));
7857 }
7861 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7880 /* Note that the operand of this must be an int
7881 and its values must be 0 or 1.
7882 ("true" is a fixed value perhaps depending on the language,
7883 but we don't handle values other than 1 correctly yet.) */
7890 /* Fold *&X to X if X is an lvalue. */
7892 {
7899 }
7905 }
7908 /* If the operation was a conversion do _not_ mark a resulting constant
7909 with TREE_OVERFLOW if the original constant was not. These conversions
7910 have implementation defined behavior and retaining the TREE_OVERFLOW
7911 flag here would confuse later passes such as VRP. */
7912 tree
7915 {
7924 }
7926 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7927 operands OP0 and OP1. LOC is the location of the resulting expression.
7928 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7929 Return the folded expression if folding is successful. Otherwise,
7930 return NULL_TREE. */
7931 static tree
7934 {
7935 tree tem;
7937 /* We only do these simplifications if we are optimizing. */
7941 /* Check for things like (A || B) && (A || C). We can convert this
7942 to A || (B && C). Note that either operator can be any of the four
7943 truth and/or operations and the transformation will still be
7944 valid. Also note that we only care about order for the
7945 ANDIF and ORIF operators. If B contains side effects, this
7946 might change the truth-value of A. */
7953 {
7973 /* This case if tricky because we must either have commutative
7974 operators or else A10 must not have side-effects. */
7980 a01);
7981 }
7983 /* See if we can build a range comparison. */
7989 {
7993 }
7997 {
8001 }
8003 /* Check for the possibility of merging component references. If our
8004 lhs is another similar operation, try to merge its rhs with our
8005 rhs. Then try to merge our lhs and rhs. */
8019 {
8026 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8027 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8028 We don't want to pack more than two leafs to a non-IF AND/OR
8029 expression.
8030 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8031 equal to IF-CODE, then we don't want to add right-hand operand.
8032 If the inner right-hand side of left-hand operand has
8033 side-effects, or isn't simple, then we can't add to it,
8034 as otherwise we might destroy if-sequence. */
8037 /* Needed for sequence points to handle trappings, and
8038 side-effects. */
8040 {
8042 arg1);
8044 tem);
8045 }
8046 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8047 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8050 /* Needed for sequence points to handle trappings, and
8051 side-effects. */
8053 {
8058 }
8059 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8060 into (A OR B).
8061 For sequence point consistancy, we need to check for trapping,
8062 and side-effects. */
8066 }
8069 }
8071 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8072 by changing CODE to reduce the magnitude of constants involved in
8073 ARG0 of the comparison.
8074 Returns a canonicalized comparison tree if a simplification was
8075 possible, otherwise returns NULL_TREE.
8076 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8077 valid if signed overflow is undefined. */
8079 static tree
8083 {
8088 /* Match A +- CST code arg1. We can change this only if overflow
8089 is undefined. */
8092 /* In principle pointers also have undefined overflow behavior,
8093 but that causes problems elsewhere. */
8100 /* Identify the constant in arg0 and its sign. */
8104 /* Overflowed constants and zero will cause problems. */
8109 /* See if we can reduce the magnitude of the constant in
8110 arg0 by changing the comparison code. */
8111 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8115 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8119 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8123 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8127 else
8131 /* Now build the constant reduced in magnitude. But not if that
8132 would produce one outside of its types range. */
8148 }
8150 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8151 overflow further. Try to decrease the magnitude of constants involved
8152 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8153 and put sole constants at the second argument position.
8154 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8156 static tree
8159 {
8160 tree t;
8165 /* Try canonicalization by simplifying arg0. */
8170 {
8174 }
8176 /* Try canonicalization by simplifying arg1 using the swapped
8177 comparison. */
8185 }
8187 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8188 space. This is used to avoid issuing overflow warnings for
8189 expressions like &p->x which can not wrap. */
8191 static bool
8193 {
8200 wide_int wi_offset;
8206 else
8222 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8223 array. */
8225 {
8226 HOST_WIDE_INT base_size;
8231 }
8234 }
8236 /* Return a positive integer when the symbol DECL is known to have
8237 a nonzero address, zero when it's known not to (e.g., it's a weak
8238 symbol), and a negative integer when the symbol is not yet in the
8239 symbol table and so whether or not its address is zero is unknown.
8240 For function local objects always return positive integer. */
8241 static int
8243 {
8248 /* Function local objects are never NULL. */
8256 }
8258 /* Subroutine of fold_binary. This routine performs all of the
8259 transformations that are common to the equality/inequality
8260 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8261 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8262 fold_binary should call fold_binary. Fold a comparison with
8263 tree code CODE and type TYPE with operands OP0 and OP1. Return
8264 the folded comparison or NULL_TREE. */
8266 static tree
8269 {
8279 /* For comparisons of pointers we can decompose it to a compile time
8280 comparison of the base objects and the offsets into the object.
8281 This requires at least one operand being an ADDR_EXPR or a
8282 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8288 {
8291 machine_mode mode;
8295 /* Get base and offset for the access. Strip ADDR_EXPR for
8296 get_inner_reference, but put it back by stripping INDIRECT_REF
8297 off the base object if possible. indirect_baseN will be true
8298 if baseN is not an address but refers to the object itself. */
8301 {
8302 base0
8308 else
8310 }
8312 {
8316 {
8317 base0
8323 else
8325 }
8328 else
8332 {
8338 {
8341 }
8342 }
8343 }
8347 {
8348 base1
8354 else
8356 }
8358 {
8362 {
8363 base1
8369 else
8371 }
8374 else
8378 {
8384 {
8387 }
8388 }
8389 }
8391 /* If we have equivalent bases we might be able to simplify. */
8395 {
8396 /* We can fold this expression to a constant if the non-constant
8397 offset parts are equal. */
8401 && (equality_code
8402 || (indirect_base0
8406 {
8412 "occur when comparing P +- C1 with "
8414 WARN_STRICT_OVERFLOW_CONDITIONAL);
8417 {
8431 }
8432 }
8433 /* We can simplify the comparison to a comparison of the variable
8434 offset parts if the constant offset parts are equal.
8435 Be careful to use signed sizetype here because otherwise we
8436 mess with array offsets in the wrong way. This is possible
8437 because pointer arithmetic is restricted to retain within an
8438 object and overflow on pointer differences is undefined as of
8439 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8441 && (equality_code
8442 || (indirect_base0
8445 {
8446 /* By converting to signed sizetype we cover middle-end pointer
8447 arithmetic which operates on unsigned pointer types of size
8448 type size and ARRAY_REF offsets which are properly sign or
8449 zero extended from their type in case it is narrower than
8450 sizetype. */
8453 else
8457 else
8464 "occur when comparing P +- C1 with "
8466 WARN_STRICT_OVERFLOW_COMPARISON);
8469 }
8470 }
8471 /* For equal offsets we can simplify to a comparison of the
8472 base addresses. */
8474 && (indirect_base0
8476 && (indirect_base1
8481 {
8487 }
8488 /* Comparison between an ordinary (non-weak) symbol and a null
8489 pointer can be eliminated since such symbols must have a non
8490 null address. In C, relational expressions between pointers
8491 to objects and null pointers are undefined. The results
8492 below follow the C++ rules with the additional property that
8493 every object pointer compares greater than a null pointer.
8494 */
8497 /* Avoid folding references to struct members at offset 0 to
8498 prevent tests like '&ptr->firstmember == 0' from getting
8499 eliminated. When ptr is null, although the -> expression
8500 is strictly speaking invalid, GCC retains it as a matter
8501 of QoI. See PR c/44555. */
8504 && indirect_base0
8505 /* The caller guarantees that when one of the arguments is
8506 constant (i.e., null in this case) it is second. */
8508 {
8510 {
8521 }
8522 }
8523 }
8525 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8526 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8527 the resulting offset is smaller in absolute value than the
8528 original one and has the same sign. */
8537 {
8542 tree cst;
8544 "occur when combining constants around "
8547 /* Put the constant on the side where it doesn't overflow and is
8548 of lower absolute value and of same sign than before. */
8555 {
8558 variable1,
8562 }
8570 {
8576 variable2);
8577 }
8578 }
8584 /* If we are comparing an expression that just has comparisons
8585 of two integer values, arithmetic expressions of those comparisons,
8586 and constants, we can simplify it. There are only three cases
8587 to check: the two values can either be equal, the first can be
8588 greater, or the second can be greater. Fold the expression for
8589 those three values. Since each value must be 0 or 1, we have
8590 eight possibilities, each of which corresponds to the constant 0
8591 or 1 or one of the six possible comparisons.
8593 This handles common cases like (a > b) == 0 but also handles
8594 expressions like ((x > y) - (y > x)) > 0, which supposedly
8595 occur in macroized code. */
8598 {
8603 /* Don't handle degenerate cases here; they should already
8604 have been handled anyway. */
8613 {
8617 /* We can't just pass T to eval_subst in case cval1 or cval2
8618 was the same as ARG1. */
8620 tree high_result
8624 arg1);
8625 tree equal_result
8629 arg1);
8630 tree low_result
8634 arg1);
8636 /* All three of these results should be 0 or 1. Confirm they are.
8637 Then use those values to select the proper code to use. */
8642 {
8643 /* Make a 3-bit mask with the high-order bit being the
8644 value for `>', the next for '=', and the low for '<'. */
8648 {
8650 /* Always false. */
8671 /* Always true. */
8673 }
8676 {
8680 }
8682 }
8683 }
8684 }
8686 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8687 into a single range test. */
8694 {
8698 }
8701 }
8704 /* Subroutine of fold_binary. Optimize complex multiplications of the
8705 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8706 argument EXPR represents the expression "z" of type TYPE. */
8708 static tree
8710 {
8715 {
8718 }
8720 {
8723 }
8724 else
8725 {
8729 }
8738 }
8741 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8742 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8744 static bool
8746 {
8750 {
8753 }
8755 {
8761 else
8763 }
8764 else
8770 }
8772 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8773 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8774 NULL_TREE otherwise. */
8776 static tree
8778 {
8795 {
8799 }
8802 {
8808 }
8809 else
8811 }
8813 /* Try to fold a pointer difference of type TYPE two address expressions of
8814 array references AREF0 and AREF1 using location LOC. Return a
8815 simplified expression for the difference or NULL_TREE. */
8817 static tree
8820 {
8825 /* If the bases are array references as well, recurse. If the bases
8826 are pointer indirections compute the difference of the pointers.
8827 If the bases are equal, we are set. */
8830 && (base_offset
8834 && (base_offset
8840 {
8846 base_offset,
8849 }
8851 }
8853 /* If the real or vector real constant CST of type TYPE has an exact
8854 inverse, return it, else return NULL. */
8856 tree
8858 {
8859 REAL_VALUE_TYPE r;
8861 machine_mode mode;
8865 {
8881 {
8886 }
8892 }
8893 }
8895 /* Mask out the tz least significant bits of X of type TYPE where
8896 tz is the number of trailing zeroes in Y. */
8897 static wide_int
8899 {
8904 }
8906 /* Return true when T is an address and is known to be nonzero.
8907 For floating point we further ensure that T is not denormal.
8908 Similar logic is present in nonzero_address in rtlanal.h.
8910 If the return value is based on the assumption that signed overflow
8911 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8912 change *STRICT_OVERFLOW_P. */
8914 static bool
8916 {
8920 /* Doing something useful for floating point would need more work. */
8926 {
8929 strict_overflow_p);
8935 strict_overflow_p);
8943 }
8946 {
8949 strict_overflow_p);
8957 strict_overflow_p);
8972 strict_overflow_p);
8976 strict_overflow_p);
8979 {
8991 }
8995 }
8997 }
8999 /* Return true when T is an address and is known to be nonzero.
9000 Handle warnings about undefined signed overflow. */
9002 bool
9004 {
9011 "determining that expression is always "
9013 WARN_STRICT_OVERFLOW_MISC);
9015 }
9017 /* Return true if T is known not to be equal to an integer W. */
9019 bool
9021 {
9023 value_range_type rtype;
9025 {
9034 {
9039 }
9044 /* If T has some known zero bits and W has any of those bits set,
9045 then T is known not to be equal to W. */
9053 }
9054 }
9056 /* Fold a binary expression of code CODE and type TYPE with operands
9057 OP0 and OP1. LOC is the location of the resulting expression.
9058 Return the folded expression if folding is successful. Otherwise,
9059 return NULL_TREE. */
9061 tree
9064 {
9079 /* Strip any conversions that don't change the mode. This is
9080 safe for every expression, except for a comparison expression
9081 because its signedness is derived from its operands. So, in
9082 the latter case, only strip conversions that don't change the
9083 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9084 preserved.
9086 Note that this is done as an internal manipulation within the
9087 constant folder, in order to find the simplest representation
9088 of the arguments so that their form can be studied. In any
9089 cases, the appropriate type conversions should be put back in
9090 the tree that will get out of the constant folder. */
9093 {
9096 }
9097 else
9098 {
9101 }
9103 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9104 constant but we can't do arithmetic on them. */
9106 {
9109 {
9113 }
9114 }
9116 /* If this is a commutative operation, and ARG0 is a constant, move it
9117 to ARG1 to reduce the number of tests below. */
9122 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9123 to ARG1 to reduce the number of tests below. */
9132 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9134 First check for cases where an arithmetic operation is applied to a
9135 compound, conditional, or comparison operation. Push the arithmetic
9136 operation inside the compound or conditional to see if any folding
9137 can then be done. Convert comparison to conditional for this purpose.
9138 The also optimizes non-constant cases that used to be done in
9139 expand_expr.
9141 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9142 one of the operands is a comparison and the other is a comparison, a
9143 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9144 code below would make the expression more complex. Change it to a
9145 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9146 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9159 {
9163 boolean_type_node,
9171 }
9175 {
9177 {
9182 tem);
9183 }
9185 {
9190 tem);
9191 }
9196 {
9202 }
9207 {
9213 }
9214 }
9217 {
9219 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9222 {
9228 }
9230 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9233 {
9234 tree base;
9235 HOST_WIDE_INT coffset;
9244 }
9249 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9255 arg1),
9257 arg0)));
9263 {
9264 /* X + (X / CST) * -CST is X % CST. */
9269 {
9278 cst0));
9279 }
9280 }
9282 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9283 one. Make sure the type is not saturating and has the signedness of
9284 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9285 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9292 {
9296 }
9299 {
9300 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9301 (plus (plus (mult) (mult)) (foo)) so that we can
9302 take advantage of the factoring cases below. */
9311 {
9317 else
9330 parg0),
9332 marg)),
9336 return
9342 parg1)));
9343 }
9344 }
9345 else
9346 {
9347 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9348 to __complex__ ( x, y ). This is not the same for SNaNs or
9349 if signed zeros are involved. */
9353 {
9360 {
9364 {
9370 }
9372 {
9378 }
9379 }
9380 }
9388 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9389 We associate floats only if the user has specified
9390 -fassociative-math. */
9394 {
9399 {
9400 tree tree0;
9403 }
9404 }
9405 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9406 We associate floats only if the user has specified
9407 -fassociative-math. */
9411 {
9416 {
9417 tree tree0;
9420 }
9421 }
9422 }
9424 bit_rotate:
9425 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9426 is a rotate of A by C1 bits. */
9427 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9428 is a rotate of A by B bits. */
9429 {
9431 tree rtype;
9440 /* Only create rotates in complete modes. Other cases are not
9441 expanded properly. */
9444 {
9458 {
9462 code0 == LSHIFT_EXPR
9466 }
9468 {
9476 element_precision
9480 return
9483 ? LROTATE_EXPR
9488 }
9490 {
9498 element_precision
9502 return fold_convert_loc
9505 ? LROTATE_EXPR
9509 }
9510 }
9511 }
9513 associate:
9514 /* In most languages, can't associate operations on floats through
9515 parentheses. Rather than remember where the parentheses were, we
9516 don't associate floats at all, unless the user has specified
9517 -fassociative-math.
9518 And, we need to make sure type is not saturating. */
9522 {
9528 /* Split both trees into variables, constants, and literals. Then
9529 associate each group together, the constants with literals,
9530 then the result with variables. This increases the chances of
9531 literals being recombined later and of generating relocatable
9532 expressions for the sum of a constant and literal. */
9538 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9542 /* With undefined overflow prefer doing association in a type
9543 which wraps on overflow, if that is one of the operand types. */
9546 {
9554 }
9556 /* With undefined overflow we can only associate constants with one
9557 variable, and constants whose association doesn't overflow. */
9560 {
9562 {
9568 {
9571 }
9578 {
9581 }
9587 /* The only case we can still associate with two variables
9588 is if they cancel out. */
9592 }
9593 }
9595 /* Only do something if we found more than two objects. Otherwise,
9596 nothing has changed and we risk infinite recursion. */
9602 {
9614 /* Preserve the MINUS_EXPR if the negative part of the literal is
9615 greater than the positive part. Otherwise, the multiplicative
9616 folding code (i.e extract_muldiv) may be fooled in case
9617 unsigned constants are subtracted, like in the following
9618 example: ((X*2 + 4) - 8U)/2. */
9620 {
9624 {
9628 }
9629 else
9630 {
9634 }
9635 }
9637 /* Don't introduce overflows through reassociation. */
9644 {
9646 return
9650 else
9651 {
9654 return
9658 }
9659 }
9662 return
9665 }
9666 }
9671 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9679 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9680 __complex__ ( x, -y ). This is not the same for SNaNs or if
9681 signed zeros are involved. */
9685 {
9692 {
9696 {
9698 arg1r ? arg1r
9703 }
9705 {
9709 arg1i ? arg1i
9712 }
9713 }
9714 }
9716 /* A - B -> A + (-B) if B is easily negatable. */
9720 /* Avoid this transformation if B is a positive REAL_CST. */
9728 /* Fold &a[i] - &a[j] to i-j. */
9733 {
9739 }
9742 && flag_unsafe_math_optimizations
9748 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9749 one. Make sure the type is not saturating and has the signedness of
9750 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9751 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9758 {
9762 }
9768 {
9769 /* Transform x * -C into -x * C if x is easily negatable. */
9783 {
9786 "occur when simplifying "
9788 WARN_STRICT_OVERFLOW_MISC);
9790 }
9792 /* Optimize z * conj(z) for integer complex numbers. */
9799 }
9800 else
9801 {
9802 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9803 This is not the same for NaNs or if signed zeros are
9804 involved. */
9810 {
9813 return
9819 return
9824 }
9826 /* Optimize z * conj(z) for floating point complex numbers.
9827 Guarded by flag_unsafe_math_optimizations as non-finite
9828 imaginary components don't produce scalar results. */
9837 }
9841 /* Canonicalize (X & C1) | C2. */
9845 {
9850 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9858 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9863 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9864 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9865 mode which allows further optimizations. */
9870 {
9874 {
9877 }
9878 }
9885 c3)),
9886 arg1);
9887 }
9889 /* See if this can be simplified into a rotate first. If that
9890 is unsuccessful continue in the association code. */
9894 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9902 /* See if this can be simplified into a rotate first. If that
9903 is unsuccessful continue in the association code. */
9907 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9912 {
9913 tree tem2;
9920 }
9921 /* Fold ~X & 1 as (X & 1) == 0. */
9925 {
9926 tree tem2;
9933 }
9934 /* Fold !X & 1 as X == 0. */
9937 {
9941 }
9943 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9944 multiple of 1 << CST. */
9946 {
9953 }
9955 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
9956 bits from CST2. */
9960 {
9968 {
9969 /* Avoid the transform if arg1 is a mask of some
9970 mode which allows further optimizations. */
9977 }
9978 }
9980 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
9981 ((A & N) + B) & M -> (A + B) & M
9982 Similarly if (N & M) == 0,
9983 ((A | N) + B) & M -> (A + B) & M
9984 and for - instead of + (or unary - instead of +)
9985 and/or ^ instead of |.
9986 If B is constant and (B & M) == 0, fold into A & M. */
9988 {
9997 {
10000 wide_int cst0;
10002 /* Now we know that arg0 is (C + D) or (C - D) or
10003 -C and arg1 (M) is == (1LL << cst) - 1.
10004 Store C into PMOP[0] and D into PMOP[1]. */
10008 {
10011 }
10018 {
10028 {
10031 }
10034 /* If C or D is of the form (A & N) where
10035 (N & M) == M, or of the form (A | N) or
10036 (A ^ N) where (N & M) == 0, replace it with A. */
10040 /* If C or D is a N where (N & M) == 0, it can be
10041 omitted (assumed 0). */
10049 }
10051 /* Only build anything new if we optimized one or both arguments
10052 above. */
10056 {
10059 {
10060 /* Perform the operations in a type that has defined
10061 overflow behavior. */
10067 }
10072 {
10080 else
10082 }
10085 else
10088 /* TEM is now the new binary +, - or unary - replacement. */
10092 }
10093 }
10094 }
10096 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10099 {
10104 return
10106 }
10111 /* Don't touch a floating-point divide by zero unless the mode
10112 of the constant can represent infinity. */
10118 /* (-A) / (-B) -> A / B */
10130 /* Fall through */
10133 /* Simplify A / (B << N) where A and B are positive and B is
10134 a power of 2, to A >> (N + log2(B)). */
10139 {
10142 {
10150 WARN_STRICT_OVERFLOW_MISC);
10156 }
10157 }
10159 /* Fall through */
10167 /* Convert -A / -B to A / B when the type is signed and overflow is
10168 undefined. */
10172 {
10175 "when distributing negation across "
10177 WARN_STRICT_OVERFLOW_MISC);
10182 }
10186 {
10189 "when distributing negation across "
10191 WARN_STRICT_OVERFLOW_MISC);
10196 }
10198 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10199 operation, EXACT_DIV_EXPR.
10201 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10202 At one time others generated faster code, it's not clear if they do
10203 after the last round to changes to the DIV code in expmed.c. */
10214 {
10218 WARN_STRICT_OVERFLOW_MISC);
10220 }
10232 {
10236 WARN_STRICT_OVERFLOW_MISC);
10238 }
10246 /* Since negative shift count is not well-defined,
10247 don't try to compute it in the compiler. */
10253 /* If we have a rotate of a bit operation with the rotate count and
10254 the second operand of the bit operation both constant,
10255 permute the two operations. */
10261 {
10269 }
10271 /* Two consecutive rotates adding up to the some integer
10272 multiple of the precision of the type can be ignored. */
10287 /* Note that the operands of this must be ints
10288 and their values must be 0 or 1.
10289 ("true" is a fixed value perhaps depending on the language.) */
10290 /* If first arg is constant zero, return it. */
10293 /* FALLTHRU */
10295 /* If either arg is constant true, drop it. */
10299 /* Preserve sequence points. */
10302 /* If second arg is constant zero, result is zero, but first arg
10303 must be evaluated. */
10306 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10307 case will be handled here. */
10311 /* !X && X is always false. */
10315 /* X && !X is always false. */
10320 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10321 means A >= Y && A != MAX, but in this case we know that
10322 A < X <= MAX. */
10326 {
10334 }
10343 /* Note that the operands of this must be ints
10344 and their values must be 0 or true.
10345 ("true" is a fixed value perhaps depending on the language.) */
10346 /* If first arg is constant true, return it. */
10349 /* FALLTHRU */
10351 /* If either arg is constant zero, drop it. */
10355 /* Preserve sequence points. */
10358 /* If second arg is constant true, result is true, but we must
10359 evaluate first arg. */
10362 /* Likewise for first arg, but note this only occurs here for
10363 TRUTH_OR_EXPR. */
10367 /* !X || X is always true. */
10371 /* X || !X is always true. */
10376 /* (X && !Y) || (!X && Y) is X ^ Y */
10379 {
10396 }
10405 /* If the second arg is constant zero, drop it. */
10408 /* If the second arg is constant true, this is a logical inversion. */
10410 {
10413 }
10414 /* Identical arguments cancel to zero. */
10418 /* !X ^ X is always true. */
10423 /* X ^ !X is always true. */
10439 /* bool_var != 1 becomes !bool_var. */
10446 /* bool_var == 0 becomes !bool_var. */
10453 /* !exp != 0 becomes !exp */
10458 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10467 {
10473 }
10475 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10484 {
10490 }
10492 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10500 code == NE_EXPR
10504 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10512 code == NE_EXPR
10516 /* If this is an EQ or NE comparison with zero and ARG0 is
10517 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10518 two operations, but the latter can be done in one less insn
10519 on machines that have only two-operand insns or on which a
10520 constant cannot be the first operand. */
10523 {
10528 {
10535 arg1);
10536 }
10539 {
10546 arg1);
10547 }
10548 }
10550 /* If this is an NE or EQ comparison of zero against the result of a
10551 signed MOD operation whose second operand is a power of 2, make
10552 the MOD operation unsigned since it is simpler and equivalent. */
10560 {
10570 }
10572 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10573 C1 is a valid shift constant, and C2 is a power of two, i.e.
10574 a single bit. */
10578 == INTEGER_CST
10581 {
10586 /* Check for a valid shift count. */
10588 {
10592 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10593 can be rewritten as (X & (C2 << C1)) != 0. */
10595 {
10600 }
10601 /* Otherwise, for signed (arithmetic) shifts,
10602 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10603 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10607 /* Otherwise, of unsigned (logical) shifts,
10608 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10609 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10610 else
10614 arg000);
10615 }
10616 }
10618 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10619 Similarly for NE_EXPR. */
10623 {
10627 tree dandnotc
10630 notc);
10634 }
10636 /* If this is a comparison of a field, we may be able to simplify it. */
10639 /* Handle the constant case even without -O
10640 to make sure the warnings are given. */
10642 {
10646 }
10648 /* Optimize comparisons of strlen vs zero to a compare of the
10649 first character of the string vs zero. To wit,
10650 strlen(ptr) == 0 => *ptr == 0
10651 strlen(ptr) != 0 => *ptr != 0
10652 Other cases should reduce to one of these two (or a constant)
10653 due to the return value of strlen being unsigned. */
10656 {
10664 {
10669 }
10670 }
10672 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10673 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10677 {
10682 {
10684 {
10687 }
10690 }
10691 }
10693 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10694 (X & C) == 0 when C is a single bit. */
10699 {
10706 arg1));
10707 }
10709 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10710 constant C is a power of two, i.e. a single bit. */
10717 {
10721 }
10723 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10724 when is C is a power of two, i.e. a single bit. */
10731 {
10737 }
10741 {
10744 }
10746 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10749 {
10762 arg01),
10771 arg01),
10780 arg00),
10789 arg00),
10791 }
10795 {
10802 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10803 operand_equal_p guarantees no side-effects so we don't need
10804 to use omit_one_operand on Z. */
10808 arg10));
10812 arg11));
10816 arg10));
10820 arg11));
10822 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10825 {
10831 }
10832 }
10834 /* Attempt to simplify equality/inequality comparisons of complex
10835 values. Only lower the comparison if the result is known or
10836 can be simplified to a single scalar comparison. */
10841 {
10846 {
10849 }
10850 else
10851 {
10854 }
10857 {
10860 }
10861 else
10862 {
10865 }
10869 {
10871 {
10876 }
10877 else
10878 {
10883 }
10884 }
10888 {
10890 {
10895 }
10896 else
10897 {
10902 }
10903 }
10904 }
10916 /* Transform comparisons of the form X +- C CMP X. */
10923 {
10930 else
10933 /* (X - c) > X becomes false. */
10937 {
10941 "occur when assuming that (X - c) > X "
10943 WARN_STRICT_OVERFLOW_ALL);
10945 }
10947 /* Likewise (X + c) < X becomes false. */
10951 {
10955 "occur when assuming that "
10957 WARN_STRICT_OVERFLOW_ALL);
10959 }
10961 /* Convert (X - c) <= X to true. */
10966 {
10970 "occur when assuming that "
10972 WARN_STRICT_OVERFLOW_ALL);
10974 }
10976 /* Convert (X + c) >= X to true. */
10981 {
10985 "occur when assuming that "
10987 WARN_STRICT_OVERFLOW_ALL);
10989 }
10992 {
10993 /* Convert X + c > X and X - c < X to true for integers. */
10997 {
11000 "not occur when assuming that "
11002 WARN_STRICT_OVERFLOW_ALL);
11004 }
11009 {
11012 "not occur when assuming that "
11014 WARN_STRICT_OVERFLOW_ALL);
11016 }
11018 /* Convert X + c <= X and X - c >= X to false for integers. */
11022 {
11025 "not occur when assuming that "
11027 WARN_STRICT_OVERFLOW_ALL);
11029 }
11034 {
11037 "not occur when assuming that "
11039 WARN_STRICT_OVERFLOW_ALL);
11041 }
11042 }
11043 }
11045 /* If we are comparing an ABS_EXPR with a constant, we can
11046 convert all the cases into explicit comparisons, but they may
11047 well not be faster than doing the ABS and one comparison.
11048 But ABS (X) <= C is a range comparison, which becomes a subtraction
11049 and a comparison, and is probably faster. */
11063 /* Convert ABS_EXPR<x> >= 0 to true. */
11070 {
11073 "when simplifying comparison of "
11075 WARN_STRICT_OVERFLOW_CONDITIONAL);
11078 arg0);
11079 }
11081 /* Convert ABS_EXPR<x> < 0 to false. */
11086 {
11089 "when simplifying comparison of "
11091 WARN_STRICT_OVERFLOW_CONDITIONAL);
11094 arg0);
11095 }
11097 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11098 and similarly for >= into !=. */
11108 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11109 otherwise Y might be >= # of bits in X's type and thus e.g.
11110 (unsigned char) (1 << Y) for Y 15 might be 0.
11111 If the cast is widening, then 1 << Y should have unsigned type,
11112 otherwise if Y is number of bits in the signed shift type minus 1,
11113 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11114 31 might be 0xffffffff80000000. */
11125 {
11131 }
11143 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11144 {
11156 }
11161 /* When pedantic, a compound expression can be neither an lvalue
11162 nor an integer constant expression. */
11165 /* Don't let (0, 0) be null pointer constant. */
11171 /* An ASSERT_EXPR should never be passed to fold_binary. */
11177 }
11179 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11180 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11181 of GOTO_EXPR. */
11183 static tree
11185 {
11187 {
11194 /* fall through */
11198 }
11199 }
11201 /* Return whether the sub-tree ST contains a label which is accessible from
11202 outside the sub-tree. */
11204 static bool
11206 {
11207 return
11209 }
11211 /* Fold a ternary expression of code CODE and type TYPE with operands
11212 OP0, OP1, and OP2. Return the folded expression if folding is
11213 successful. Otherwise, return NULL_TREE. */
11215 tree
11218 {
11219 tree tem;
11226 /* If this is a commutative operation, and OP0 is a constant, move it
11227 to OP1 to reduce the number of tests below. */
11236 /* Strip any conversions that don't change the mode. This is safe
11237 for every expression, except for a comparison expression because
11238 its signedness is derived from its operands. So, in the latter
11239 case, only strip conversions that don't change the signedness.
11241 Note that this is done as an internal manipulation within the
11242 constant folder, in order to find the simplest representation of
11243 the arguments so that their form can be studied. In any cases,
11244 the appropriate type conversions should be put back in the tree
11245 that will get out of the constant folder. */
11247 {
11250 }
11253 {
11256 }
11259 {
11262 }
11265 {
11269 {
11275 }
11280 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11281 so all simple results must be passed through pedantic_non_lvalue. */
11283 {
11286 /* Only optimize constant conditions when the selected branch
11287 has the same type as the COND_EXPR. This avoids optimizing
11288 away "c ? x : throw", where the throw has a void type.
11289 Avoid throwing away that operand which contains label. */
11296 }
11298 {
11303 {
11308 {
11316 }
11320 }
11321 }
11323 /* If we have A op B ? A : C, we may be able to convert this to a
11324 simpler expression, depending on the operation and the values
11325 of B and C. Signed zeros prevent all of these transformations,
11326 for reasons given above each one.
11328 Also try swapping the arguments and inverting the conditional. */
11333 {
11337 }
11341 op2,
11344 {
11348 {
11352 }
11353 }
11355 /* If the second operand is simpler than the third, swap them
11356 since that produces better jump optimization results. */
11359 {
11361 /* See if this can be inverted. If it can't, possibly because
11362 it was a floating-point inequality comparison, don't do
11363 anything. */
11367 }
11369 /* Convert A ? 1 : 0 to simply A. */
11374 /* If we try to convert OP0 to our type, the
11375 call to fold will try to move the conversion inside
11376 a COND, which will recurse. In that case, the COND_EXPR
11377 is probably the best choice, so leave it alone. */
11381 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11382 over COND_EXPR in cases such as floating point comparisons. */
11391 arg0)));
11393 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11398 {
11399 /* sign_bit_p looks through both zero and sign extensions,
11400 but for this optimization only sign extensions are
11401 usable. */
11404 {
11407 {
11410 }
11412 }
11413 /* sign_bit_p only checks ARG1 bits within A's precision.
11414 If <sign bit of A> has wider type than A, bits outside
11415 of A's precision in <sign bit of A> need to be checked.
11416 If they are all 0, this optimization needs to be done
11417 in unsigned A's type, if they are all 1 in signed A's type,
11418 otherwise this can't be done. */
11424 {
11426 tree tem_type;
11439 {
11442 }
11444 {
11447 }
11448 else
11450 }
11453 return
11459 arg1)));
11460 }
11462 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11463 already handled above. */
11468 {
11477 }
11479 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11480 is probably obsolete because the first operand should be a
11481 truth value (that's why we have the two cases above), but let's
11482 leave it in until we can confirm this for all front-ends. */
11494 /* Disable the transformations below for vectors, since
11495 fold_binary_op_with_conditional_arg may undo them immediately,
11496 yielding an infinite loop. */
11500 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11509 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11514 {
11516 /* Only perform transformation if ARG0 is easily inverted. */
11520 ? BIT_IOR_EXPR
11523 arg1);
11524 }
11526 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11531 {
11533 /* Only perform transformation if ARG0 is easily inverted. */
11539 op2);
11540 }
11542 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11554 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11555 of fold_ternary on them. */
11563 {
11573 {
11578 {
11586 }
11587 }
11588 }
11590 /* On constants we can use native encode/interpret to constant
11591 fold (nearly) all BIT_FIELD_REFs. */
11595 {
11598 /* Limit us to a reasonable amount of work. To relax the
11599 other limitations we need bit-shifting of the buffer
11600 and rounding up the size. */
11604 {
11606 unsigned HOST_WIDE_INT len
11611 {
11616 }
11617 }
11618 }
11623 /* For integers we can decompose the FMA if possible. */
11635 {
11651 {
11656 /* Make sure that the perm value is in an acceptable
11657 range. */
11666 else
11671 }
11674 {
11679 }
11684 {
11689 }
11695 {
11699 }
11704 /* Some targets are deficient and fail to expand a single
11705 argument permutation while still allowing an equivalent
11706 2-argument version. */
11710 {
11713 }
11716 {
11723 }
11727 }
11731 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11734 {
11740 wide_int tem2
11744 }
11749 {
11751 unsigned HOST_WIDE_INT elsize
11754 {
11758 else
11759 {
11765 }
11766 }
11767 }
11773 }
11775 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11776 of an array (or vector). */
11778 tree
11780 {
11785 {
11788 {
11789 /* Static constructors for variably sized objects makes no sense. */
11793 }
11794 }
11805 offset_int max_index;
11810 {
11811 /* Array constructor might explicitly set index, or specify a range,
11812 or leave index NULL meaning that it is next index after previous
11813 one. */
11815 {
11818 else
11819 {
11823 }
11824 }
11825 else
11826 {
11832 }
11834 /* Do we have match? */
11838 }
11840 }
11842 /* Perform constant folding and related simplification of EXPR.
11843 The related simplifications include x*1 => x, x*0 => 0, etc.,
11844 and application of the associative law.
11845 NOP_EXPR conversions may be removed freely (as long as we
11846 are careful not to change the type of the overall expression).
11847 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11848 but we can constant-fold them if they have constant operands. */
11850 #ifdef ENABLE_FOLD_CHECKING
11851 # define fold(x) fold_1 (x)
11853 static
11854 #endif
11855 tree
11857 {
11861 tree tem;
11864 /* Return right away if a constant. */
11868 /* CALL_EXPR-like objects with variable numbers of operands are
11869 treated specially. */
11871 {
11873 {
11876 }
11878 }
11881 {
11886 {
11904 }
11905 }
11908 {
11910 {
11917 {
11922 }
11925 }
11927 /* Return a VECTOR_CST if possible. */
11929 {
11935 tree val;
11941 }
11949 }
11951 #ifdef ENABLE_FOLD_CHECKING
11952 #undef fold
11959 /* When --enable-checking=fold, compute a digest of expr before
11960 and after actual fold call to see if fold did not accidentally
11961 change original expr. */
11963 tree
11965 {
11966 tree ret;
11986 }
11988 void
11990 {
12001 }
12003 static void
12005 {
12007 }
12009 static void
12012 {
12018 recursive_label:
12028 {
12029 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12034 }
12042 {
12043 /* Allow these fields to be modified. */
12044 tree tmp;
12053 {
12056 }
12057 }
12068 {
12071 {
12086 }
12090 {
12103 }
12120 {
12126 }
12129 {
12131 {
12134 }
12136 }
12147 {
12150 }
12160 }
12161 }
12163 /* Helper function for outputting the checksum of a tree T. When
12164 debugging with gdb, you can "define mynext" to be "next" followed
12165 by "call debug_fold_checksum (op0)", then just trace down till the
12166 outputs differ. */
12168 DEBUG_FUNCTION void
12170 {
12185 }
12187 #endif
12189 /* Fold a unary tree expression with code CODE of type TYPE with an
12190 operand OP0. LOC is the location of the resulting expression.
12191 Return a folded expression if successful. Otherwise, return a tree
12192 expression with code CODE of type TYPE with an operand OP0. */
12194 tree
12197 {
12198 tree tem;
12199 #ifdef ENABLE_FOLD_CHECKING
12208 #endif
12214 #ifdef ENABLE_FOLD_CHECKING
12221 #endif
12223 }
12225 /* Fold a binary tree expression with code CODE of type TYPE with
12226 operands OP0 and OP1. LOC is the location of the resulting
12227 expression. Return a folded expression if successful. Otherwise,
12228 return a tree expression with code CODE of type TYPE with operands
12229 OP0 and OP1. */
12231 tree
12234 MEM_STAT_DECL)
12235 {
12236 tree tem;
12237 #ifdef ENABLE_FOLD_CHECKING
12254 #endif
12260 #ifdef ENABLE_FOLD_CHECKING
12275 #endif
12277 }
12279 /* Fold a ternary tree expression with code CODE of type TYPE with
12280 operands OP0, OP1, and OP2. Return a folded expression if
12281 successful. Otherwise, return a tree expression with code CODE of
12282 type TYPE with operands OP0, OP1, and OP2. */
12284 tree
12287 {
12288 tree tem;
12289 #ifdef ENABLE_FOLD_CHECKING
12313 #endif
12320 #ifdef ENABLE_FOLD_CHECKING
12343 #endif
12345 }
12347 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12348 arguments in ARGARRAY, and a null static chain.
12349 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12350 of type TYPE from the given operands as constructed by build_call_array. */
12352 tree
12355 {
12356 tree tem;
12357 #ifdef ENABLE_FOLD_CHECKING
12376 #endif
12382 #ifdef ENABLE_FOLD_CHECKING
12398 #endif
12400 }
12402 /* Perform constant folding and related simplification of initializer
12403 expression EXPR. These behave identically to "fold_buildN" but ignore
12404 potential run-time traps and exceptions that fold must preserve. */
12406 #define START_FOLD_INIT \
12407 int saved_signaling_nans = flag_signaling_nans;\
12408 int saved_trapping_math = flag_trapping_math;\
12409 int saved_rounding_math = flag_rounding_math;\
12410 int saved_trapv = flag_trapv;\
12411 int saved_folding_initializer = folding_initializer;\
12412 flag_signaling_nans = 0;\
12413 flag_trapping_math = 0;\
12414 flag_rounding_math = 0;\
12415 flag_trapv = 0;\
12416 folding_initializer = 1;
12418 #define END_FOLD_INIT \
12419 flag_signaling_nans = saved_signaling_nans;\
12420 flag_trapping_math = saved_trapping_math;\
12421 flag_rounding_math = saved_rounding_math;\
12422 flag_trapv = saved_trapv;\
12423 folding_initializer = saved_folding_initializer;
12425 tree
12428 {
12429 tree result;
12430 START_FOLD_INIT;
12434 END_FOLD_INIT;
12436 }
12438 tree
12441 {
12442 tree result;
12443 START_FOLD_INIT;
12447 END_FOLD_INIT;
12449 }
12451 tree
12454 {
12455 tree result;
12456 START_FOLD_INIT;
12460 END_FOLD_INIT;
12462 }
12464 #undef START_FOLD_INIT
12465 #undef END_FOLD_INIT
12467 /* Determine if first argument is a multiple of second argument. Return 0 if
12468 it is not, or we cannot easily determined it to be.
12470 An example of the sort of thing we care about (at this point; this routine
12471 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12472 fold cases do now) is discovering that
12474 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12476 is a multiple of
12478 SAVE_EXPR (J * 8)
12480 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12482 This code also handles discovering that
12484 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12486 is a multiple of 8 so we don't have to worry about dealing with a
12487 possible remainder.
12489 Note that we *look* inside a SAVE_EXPR only to determine how it was
12490 calculated; it is not safe for fold to do much of anything else with the
12491 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12492 at run time. For example, the latter example above *cannot* be implemented
12493 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12494 evaluation time of the original SAVE_EXPR is not necessarily the same at
12495 the time the new expression is evaluated. The only optimization of this
12496 sort that would be valid is changing
12498 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12500 divided by 8 to
12502 SAVE_EXPR (I) * SAVE_EXPR (J)
12504 (where the same SAVE_EXPR (J) is used in the original and the
12505 transformed version). */
12507 int
12509 {
12520 {
12522 /* Bitwise and provides a power of two multiple. If the mask is
12523 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12526 /* FALLTHRU */
12533 /* It is impossible to prove if op0 - op1 is multiple of bottom
12534 precisely, so be conservative here checking if both op0 and op1
12535 are multiple of bottom. Note we check the second operand first
12536 since it's usually simpler. */
12541 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12542 as op0 - 3 if the expression has unsigned type. For example,
12543 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12553 {
12555 /* const_binop may not detect overflow correctly,
12556 so check for it explicitly here. */
12560 size_one_node,
12561 op1)))
12564 }
12568 /* Can't handle conversions from non-integral or wider integral type. */
12574 /* fall through */
12591 SIGNED);
12597 {
12600 /* Check for special cases to see if top is defined as multiple
12601 of bottom:
12603 top = (X & ~(bottom - 1) ; bottom is power of 2
12605 or
12607 Y = X % bottom
12608 top = X - Y. */
12627 }
12629 /* fall through */
12633 }
12634 }
12636 #define tree_expr_nonnegative_warnv_p(X, Y) \
12639 #define RECURSE(X) \
12640 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12642 /* Return true if CODE or TYPE is known to be non-negative. */
12644 static bool
12646 {
12649 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12650 have a signed:1 type (where the value is -1 and 0). */
12653 }
12655 /* Return true if (CODE OP0) is known to be non-negative. If the return
12656 value is based on the assumption that signed overflow is undefined,
12657 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12658 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12660 bool
12663 {
12668 {
12670 /* We can't return 1 if flag_wrapv is set because
12671 ABS_EXPR<INT_MIN> = INT_MIN. */
12675 {
12678 }
12686 CASE_CONVERT:
12687 {
12692 {
12696 {
12700 }
12701 }
12703 {
12709 }
12710 }
12715 }
12717 /* We don't know sign of `t', so be conservative and return false. */
12719 }
12721 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12722 value is based on the assumption that signed overflow is undefined,
12723 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12724 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12726 bool
12730 {
12735 {
12741 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12742 both unsigned and at least 2 bits shorter than the result. */
12746 {
12751 {
12755 }
12756 }
12761 {
12762 /* x * x is always non-negative for floating point x
12763 or without overflow. */
12766 {
12771 }
12772 }
12774 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12775 both unsigned and their total bits is shorter than the result. */
12779 {
12798 {
12808 }
12809 }
12836 }
12838 /* We don't know sign of `t', so be conservative and return false. */
12840 }
12842 /* Return true if T is known to be non-negative. If the return
12843 value is based on the assumption that signed overflow is undefined,
12844 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12845 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12847 bool
12849 {
12854 {
12868 /* Limit the depth of recursion to avoid quadratic behavior.
12869 This is expected to catch almost all occurrences in practice.
12870 If this code misses important cases that unbounded recursion
12871 would not, passes that need this information could be revised
12872 to provide it through dataflow propagation. */
12880 }
12881 }
12883 /* Return true if T is known to be non-negative. If the return
12884 value is based on the assumption that signed overflow is undefined,
12885 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12886 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12888 bool
12891 {
12893 {
12894 CASE_CFN_ACOS:
12895 CASE_CFN_ACOSH:
12896 CASE_CFN_CABS:
12897 CASE_CFN_COSH:
12898 CASE_CFN_ERFC:
12899 CASE_CFN_EXP:
12900 CASE_CFN_EXP10:
12901 CASE_CFN_EXP2:
12902 CASE_CFN_FABS:
12903 CASE_CFN_FDIM:
12904 CASE_CFN_HYPOT:
12905 CASE_CFN_POW10:
12906 CASE_CFN_FFS:
12907 CASE_CFN_PARITY:
12908 CASE_CFN_POPCOUNT:
12909 CASE_CFN_CLZ:
12910 CASE_CFN_CLRSB:
12913 /* Always true. */
12916 CASE_CFN_SQRT:
12917 /* sqrt(-0.0) is -0.0. */
12922 CASE_CFN_ASINH:
12923 CASE_CFN_ATAN:
12924 CASE_CFN_ATANH:
12925 CASE_CFN_CBRT:
12926 CASE_CFN_CEIL:
12927 CASE_CFN_ERF:
12928 CASE_CFN_EXPM1:
12929 CASE_CFN_FLOOR:
12930 CASE_CFN_FMOD:
12931 CASE_CFN_FREXP:
12932 CASE_CFN_ICEIL:
12933 CASE_CFN_IFLOOR:
12934 CASE_CFN_IRINT:
12935 CASE_CFN_IROUND:
12936 CASE_CFN_LCEIL:
12937 CASE_CFN_LDEXP:
12938 CASE_CFN_LFLOOR:
12939 CASE_CFN_LLCEIL:
12940 CASE_CFN_LLFLOOR:
12941 CASE_CFN_LLRINT:
12942 CASE_CFN_LLROUND:
12943 CASE_CFN_LRINT:
12944 CASE_CFN_LROUND:
12945 CASE_CFN_MODF:
12946 CASE_CFN_NEARBYINT:
12947 CASE_CFN_RINT:
12948 CASE_CFN_ROUND:
12949 CASE_CFN_SCALB:
12950 CASE_CFN_SCALBLN:
12951 CASE_CFN_SCALBN:
12952 CASE_CFN_SIGNBIT:
12953 CASE_CFN_SIGNIFICAND:
12954 CASE_CFN_SINH:
12955 CASE_CFN_TANH:
12956 CASE_CFN_TRUNC:
12957 /* True if the 1st argument is nonnegative. */
12960 CASE_CFN_FMAX:
12961 /* True if the 1st OR 2nd arguments are nonnegative. */
12964 CASE_CFN_FMIN:
12965 /* True if the 1st AND 2nd arguments are nonnegative. */
12968 CASE_CFN_COPYSIGN:
12969 /* True if the 2nd argument is nonnegative. */
12972 CASE_CFN_POWI:
12973 /* True if the 1st argument is nonnegative or the second
12974 argument is an even integer. */
12980 CASE_CFN_POW:
12981 /* True if the 1st argument is nonnegative or the second
12982 argument is an even integer valued real. */
12984 {
12985 REAL_VALUE_TYPE c;
12986 HOST_WIDE_INT n;
12991 {
12992 REAL_VALUE_TYPE cint;
12996 }
12997 }
13002 }
13004 }
13006 /* Return true if T is known to be non-negative. If the return
13007 value is based on the assumption that signed overflow is undefined,
13008 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13009 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13011 static bool
13013 {
13019 {
13021 {
13025 /* If the initializer is non-void, then it's a normal expression
13026 that will be assigned to the slot. */
13030 /* Otherwise, the initializer sets the slot in some way. One common
13031 way is an assignment statement at the end of the initializer. */
13033 {
13041 else
13043 }
13049 }
13052 {
13058 arg0,
13059 arg1,
13061 }
13074 }
13075 }
13077 #undef RECURSE
13078 #undef tree_expr_nonnegative_warnv_p
13080 /* Return true if T is known to be non-negative. If the return
13081 value is based on the assumption that signed overflow is undefined,
13082 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13083 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13085 bool
13087 {
13094 {
13116 }
13119 {
13145 }
13146 }
13148 /* Return true if `t' is known to be non-negative. Handle warnings
13149 about undefined signed overflow. */
13151 bool
13153 {
13160 "determining that expression is always "
13162 WARN_STRICT_OVERFLOW_MISC);
13164 }
13167 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13168 For floating point we further ensure that T is not denormal.
13169 Similar logic is present in nonzero_address in rtlanal.h.
13171 If the return value is based on the assumption that signed overflow
13172 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13173 change *STRICT_OVERFLOW_P. */
13175 bool
13178 {
13180 {
13183 strict_overflow_p);
13186 {
13192 strict_overflow_p));
13193 }
13198 strict_overflow_p);
13202 }
13205 }
13207 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13208 For floating point we further ensure that T is not denormal.
13209 Similar logic is present in nonzero_address in rtlanal.h.
13211 If the return value is based on the assumption that signed overflow
13212 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13213 change *STRICT_OVERFLOW_P. */
13215 bool
13217 tree type,
13218 tree op0,
13220 {
13223 {
13227 {
13228 /* With the presence of negative values it is hard
13229 to say something. */
13236 /* One of operands must be positive and the other non-negative. */
13237 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13238 overflows, on a twos-complement machine the sum of two
13239 nonnegative numbers can never be zero. */
13241 strict_overflow_p)
13243 strict_overflow_p));
13244 }
13249 {
13251 strict_overflow_p)
13253 strict_overflow_p))
13254 {
13257 }
13258 }
13267 {
13270 }
13277 {
13281 /* When both operands are nonzero, then MAX must be too. */
13283 strict_overflow_p))
13286 /* MAX where operand 0 is positive is positive. */
13288 strict_overflow_p);
13289 }
13290 /* MAX where operand 1 is positive is positive. */
13295 {
13299 }
13304 strict_overflow_p)
13306 strict_overflow_p));
13310 }
13313 }
13315 /* Return true when T is an address and is known to be nonzero.
13316 For floating point we further ensure that T is not denormal.
13317 Similar logic is present in nonzero_address in rtlanal.h.
13319 If the return value is based on the assumption that signed overflow
13320 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13321 change *STRICT_OVERFLOW_P. */
13323 bool
13325 {
13328 {
13333 {
13345 /* For objects in symbol table check if we know they are non-zero.
13346 Don't do anything for variables and functions before symtab is built;
13347 it is quite possible that they will be declared weak later. */
13352 /* Constants are never weak. */
13357 }
13365 {
13369 }
13374 }
13376 }
13378 #define integer_valued_real_p(X) \
13381 #define RECURSE(X) \
13382 ((integer_valued_real_p) (X, depth + 1))
13384 /* Return true if the floating point result of (CODE OP0) has an
13385 integer value. We also allow +Inf, -Inf and NaN to be considered
13386 integer values. Return false for signaling NaN.
13388 DEPTH is the current nesting depth of the query. */
13390 bool
13392 {
13394 {
13401 CASE_CONVERT:
13402 {
13409 }
13413 }
13415 }
13417 /* Return true if the floating point result of (CODE OP0 OP1) has an
13418 integer value. We also allow +Inf, -Inf and NaN to be considered
13419 integer values. Return false for signaling NaN.
13421 DEPTH is the current nesting depth of the query. */
13423 bool
13425 {
13427 {
13437 }
13439 }
13441 /* Return true if the floating point result of calling FNDECL with arguments
13442 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13443 considered integer values. Return false for signaling NaN. If FNDECL
13444 takes fewer than 2 arguments, the remaining ARGn are null.
13446 DEPTH is the current nesting depth of the query. */
13448 bool
13450 {
13452 {
13453 CASE_CFN_CEIL:
13454 CASE_CFN_FLOOR:
13455 CASE_CFN_NEARBYINT:
13456 CASE_CFN_RINT:
13457 CASE_CFN_ROUND:
13458 CASE_CFN_TRUNC:
13461 CASE_CFN_FMIN:
13462 CASE_CFN_FMAX:
13467 }
13469 }
13471 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13472 has an integer value. We also allow +Inf, -Inf and NaN to be
13473 considered integer values. Return false for signaling NaN.
13475 DEPTH is the current nesting depth of the query. */
13477 bool
13479 {
13481 {
13489 /* Limit the depth of recursion to avoid quadratic behavior.
13490 This is expected to catch almost all occurrences in practice.
13491 If this code misses important cases that unbounded recursion
13492 would not, passes that need this information could be revised
13493 to provide it through dataflow propagation. */
13497 depth));
13501 }
13503 }
13505 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13506 has an integer value. We also allow +Inf, -Inf and NaN to be
13507 considered integer values. Return false for signaling NaN.
13509 DEPTH is the current nesting depth of the query. */
13511 static bool
13513 {
13515 {
13526 }
13528 }
13530 #undef RECURSE
13531 #undef integer_valued_real_p
13533 /* Return true if the floating point expression T has an integer value.
13534 We also allow +Inf, -Inf and NaN to be considered integer values.
13535 Return false for signaling NaN.
13537 DEPTH is the current nesting depth of the query. */
13539 bool
13541 {
13547 {
13563 }
13566 {
13572 {
13581 }
13585 }
13586 }
13588 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13589 attempt to fold the expression to a constant without modifying TYPE,
13590 OP0 or OP1.
13592 If the expression could be simplified to a constant, then return
13593 the constant. If the expression would not be simplified to a
13594 constant, then return NULL_TREE. */
13596 tree
13598 {
13601 }
13603 /* Given the components of a unary expression CODE, TYPE and OP0,
13604 attempt to fold the expression to a constant without modifying
13605 TYPE or OP0.
13607 If the expression could be simplified to a constant, then return
13608 the constant. If the expression would not be simplified to a
13609 constant, then return NULL_TREE. */
13611 tree
13613 {
13616 }
13618 /* If EXP represents referencing an element in a constant string
13619 (either via pointer arithmetic or array indexing), return the
13620 tree representing the value accessed, otherwise return NULL. */
13622 tree
13624 {
13628 {
13630 tree index;
13631 tree string;
13636 else
13637 {
13641 /* Optimize the special-case of a zero lower bound.
13643 We convert the low_bound to sizetype to avoid some problems
13644 with constant folding. (E.g. suppose the lower bound is 1,
13645 and its mode is QI. Without the conversion,l (ARRAY
13646 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13647 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13653 }
13666 }
13668 }
13670 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13671 an integer constant, real, or fixed-point constant.
13673 TYPE is the type of the result. */
13675 static tree
13677 {
13681 {
13683 {
13690 }
13697 {
13698 FIXED_VALUE_TYPE f;
13703 /* Propagate overflow flags. */
13707 }
13711 }
13714 }
13716 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13717 an integer constant or real constant.
13719 TYPE is the type of the result. */
13721 tree
13723 {
13727 {
13729 {
13730 /* If the value is unsigned or non-negative, then the absolute value
13731 is the same as the ordinary value. */
13735 /* If the value is negative, then the absolute value is
13736 its negation. */
13737 else
13738 {
13743 }
13744 }
13750 else
13756 }
13759 }
13761 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13762 constant. TYPE is the type of the result. */
13764 static tree
13766 {
13770 }
13772 /* Given CODE, a relational operator, the target type, TYPE and two
13773 constant operands OP0 and OP1, return the result of the
13774 relational operation. If the result is not a compile time
13775 constant, then return NULL_TREE. */
13777 static tree
13779 {
13782 /* From here on, the only cases we handle are when the result is
13783 known to be a constant. */
13786 {
13790 /* Handle the cases where either operand is a NaN. */
13792 {
13794 {
13822 }
13825 }
13828 }
13831 {
13835 }
13837 /* Handle equality/inequality of complex constants. */
13839 {
13850 else
13852 }
13855 {
13857 {
13858 /* Have vector comparison with scalar boolean result. */
13862 {
13870 }
13872 }
13879 {
13891 }
13894 }
13896 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13898 To compute GT, swap the arguments and do LT.
13899 To compute GE, do LT and invert the result.
13900 To compute LE, swap the arguments, do LT and invert the result.
13901 To compute NE, do EQ and invert the result.
13903 Therefore, the code below must handle only EQ and LT. */
13906 {
13909 }
13911 /* Note that it is safe to invert for real values here because we
13912 have already handled the one case that it matters. */
13916 {
13919 }
13921 /* Compute a result for LT or EQ if args permit;
13922 Otherwise return T. */
13924 {
13927 else
13929 }
13930 else
13936 }
13938 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13939 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13940 itself. */
13942 tree
13944 {
13945 /* If the expression does not have side effects then we don't have to wrap
13946 it with a cleanup point expression. */
13950 /* If the expression is a return, check to see if the expression inside the
13951 return has no side effects or the right hand side of the modify expression
13952 inside the return. If either don't have side effects set we don't need to
13953 wrap the expression in a cleanup point expression. Note we don't check the
13954 left hand side of the modify because it should always be a return decl. */
13956 {
13963 }
13966 }
13968 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13969 of an indirection through OP0, or NULL_TREE if no simplification is
13970 possible. */
13972 tree
13974 {
13976 tree subtype;
13984 {
13987 /* *&CONST_DECL -> to the value of the const decl. */
13990 /* *&p => p; make sure to handle *&"str"[cst] here. */
13992 {
13996 else
13998 }
13999 /* *(foo *)&fooarray => fooarray[0] */
14002 && (!in_gimple_form
14004 {
14014 }
14015 /* *(foo *)&complexfoo => __real__ complexfoo */
14019 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14022 {
14026 }
14027 }
14031 {
14037 {
14038 tree op00type;
14042 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14045 {
14047 unsigned HOST_WIDE_INT max_offset
14052 {
14059 }
14060 }
14061 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14064 {
14068 }
14069 /* ((foo *)&fooarray)[1] => fooarray[1] */
14072 {
14082 }
14083 }
14084 }
14086 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14089 && (!in_gimple_form
14091 {
14092 tree type_domain;
14102 NULL_TREE);
14103 }
14106 }
14108 /* Builds an expression for an indirection through T, simplifying some
14109 cases. */
14111 tree
14113 {
14121 }
14123 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14125 tree
14127 {
14132 else
14134 }
14136 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14137 whose result is ignored. The type of the returned tree need not be
14138 the same as the original expression. */
14140 tree
14142 {
14148 {
14159 else
14165 {
14181 }
14186 }
14187 }
14189 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14191 tree
14193 {
14199 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14200 have to do anything. Only do this when we are not given a const,
14201 because in that case, this check is more expensive than just
14202 doing it. */
14204 {
14209 }
14211 /* If divisor is a power of two, simplify this to bit manipulation. */
14213 {
14215 {
14229 }
14230 else
14231 {
14232 tree t;
14238 }
14239 }
14240 else
14241 {
14246 }
14249 }
14251 /* Likewise, but round down. */
14253 tree
14255 {
14262 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14263 have to do anything. Only do this when we are not given a const,
14264 because in that case, this check is more expensive than just
14265 doing it. */
14267 {
14272 }
14274 /* If divisor is a power of two, simplify this to bit manipulation. */
14276 {
14277 tree t;
14281 }
14282 else
14283 {
14288 }
14291 }
14293 /* Returns the pointer to the base of the object addressed by EXP and
14294 extracts the information about the offset of the access, storing it
14295 to PBITPOS and POFFSET. */
14297 static tree
14300 {
14301 tree core;
14302 machine_mode mode;
14304 HOST_WIDE_INT bitsize;
14308 {
14313 }
14314 else
14315 {
14319 }
14322 }
14324 /* Returns true if addresses of E1 and E2 differ by a constant, false
14325 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14327 bool
14329 {
14343 {
14353 }
14355 {
14356 /* If only one of the offsets is non-constant, the difference cannot
14357 be a constant. */
14359 }
14360 else
14365 }
14367 /* Return OFF converted to a pointer offset type suitable as offset for
14368 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14369 tree
14371 {
14373 }
14375 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14376 tree
14378 {
14381 }
14383 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14384 tree
14386 {
14389 }
14391 /* Return a char pointer for a C string if it is a string constant
14392 or sum of string constant and integer constant. We only support
14393 string constants properly terminated with '\0' character.
14394 If STRLEN is a valid pointer, length (including terminating character)
14395 of returned string is stored to the argument. */
14399 {
14400 tree offset_node;
14411 {
14414 else
14416 }
14421 /* Support only properly null-terminated strings. */
14430 }
14432 #if CHECKING_P
14436 /* Helper functions for writing tests of folding trees. */
14438 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14440 static void
14442 tree constant)
14443 {
14445 }
14447 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14448 wrapping WRAPPED_EXPR. */
14450 static void
14452 tree wrapped_expr)
14453 {
14458 }
14460 /* Verify that various arithmetic binary operations are folded
14461 correctly. */
14463 static void
14465 {
14471 /* Addition. */
14472 /* 1 <-- (0 + 1) */
14474 one);
14476 one);
14478 /* (nonlvalue)x <-- (x + 0) */
14480 x);
14482 /* Subtraction. */
14483 /* 0 <-- (x - x) */
14485 zero);
14487 x);
14489 /* Multiplication. */
14490 /* 0 <-- (x * 0) */
14492 zero);
14494 /* (nonlvalue)x <-- (x * 1) */
14496 x);
14497 }
14499 /* Verify that various binary operations on vectors are folded
14500 correctly. */
14502 static void
14504 {
14510 /* Verify equality tests that return a scalar boolean result. */
14516 }
14518 /* Run all of the selftests within this file. */
14520 void
14522 {
14525 }