| blob | 5058746c4eb84e2fb3b9c18ccf489a2467439ee9 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
80 #ifndef LOAD_EXTEND_OP
81 #define LOAD_EXTEND_OP(M) UNKNOWN
82 #endif
84 /* Nonzero if we are folding constants inside an initializer; zero
85 otherwise. */
88 /* The following constants represent a bit based encoding of GCC's
89 comparison operators. This encoding simplifies transformations
90 on relational comparison operators, such as AND and OR. */
108 };
148 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
149 Otherwise, return LOC. */
151 static location_t
153 {
156 }
158 /* Similar to protected_set_expr_location, but never modify x in place,
159 if location can and needs to be set, unshare it. */
163 {
169 {
172 }
174 }
175 \f
176 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
177 division and returns the quotient. Otherwise returns
178 NULL_TREE. */
180 tree
182 {
183 widest_int quo;
190 }
191 \f
192 /* This is nonzero if we should defer warnings about undefined
193 overflow. This facility exists because these warnings are a
194 special case. The code to estimate loop iterations does not want
195 to issue any warnings, since it works with expressions which do not
196 occur in user code. Various bits of cleanup code call fold(), but
197 only use the result if it has certain characteristics (e.g., is a
198 constant); that code only wants to issue a warning if the result is
199 used. */
203 /* If a warning about undefined overflow is deferred, this is the
204 warning. Note that this may cause us to turn two warnings into
205 one, but that is fine since it is sufficient to only give one
206 warning per expression. */
210 /* If a warning about undefined overflow is deferred, this is the
211 level at which the warning should be emitted. */
215 /* Start deferring overflow warnings. We could use a stack here to
216 permit nested calls, but at present it is not necessary. */
218 void
220 {
222 }
224 /* Stop deferring overflow warnings. If there is a pending warning,
225 and ISSUE is true, then issue the warning if appropriate. STMT is
226 the statement with which the warning should be associated (used for
227 location information); STMT may be NULL. CODE is the level of the
228 warning--a warn_strict_overflow_code value. This function will use
229 the smaller of CODE and the deferred code when deciding whether to
230 issue the warning. CODE may be zero to mean to always use the
231 deferred code. */
233 void
235 {
237 location_t locus;
242 {
248 }
259 /* Use the smallest code level when deciding to issue the
260 warning. */
269 else
272 }
274 /* Stop deferring overflow warnings, ignoring any deferred
275 warnings. */
277 void
279 {
281 }
283 /* Whether we are deferring overflow warnings. */
285 bool
287 {
289 }
291 /* This is called when we fold something based on the fact that signed
292 overflow is undefined. */
294 void
296 {
298 {
301 {
304 }
305 }
308 }
309 \f
310 /* Return true if the built-in mathematical function specified by CODE
311 is odd, i.e. -f(x) == f(-x). */
313 bool
315 {
317 {
318 CASE_CFN_ASIN:
319 CASE_CFN_ASINH:
320 CASE_CFN_ATAN:
321 CASE_CFN_ATANH:
322 CASE_CFN_CASIN:
323 CASE_CFN_CASINH:
324 CASE_CFN_CATAN:
325 CASE_CFN_CATANH:
326 CASE_CFN_CBRT:
327 CASE_CFN_CPROJ:
328 CASE_CFN_CSIN:
329 CASE_CFN_CSINH:
330 CASE_CFN_CTAN:
331 CASE_CFN_CTANH:
332 CASE_CFN_ERF:
333 CASE_CFN_LLROUND:
334 CASE_CFN_LROUND:
335 CASE_CFN_ROUND:
336 CASE_CFN_SIN:
337 CASE_CFN_SINH:
338 CASE_CFN_TAN:
339 CASE_CFN_TANH:
340 CASE_CFN_TRUNC:
343 CASE_CFN_LLRINT:
344 CASE_CFN_LRINT:
345 CASE_CFN_NEARBYINT:
346 CASE_CFN_RINT:
351 }
353 }
355 /* Check whether we may negate an integer constant T without causing
356 overflow. */
358 bool
360 {
361 tree type;
370 }
372 /* Determine whether an expression T can be cheaply negated using
373 the function negate_expr without introducing undefined overflow. */
375 static bool
377 {
378 tree type;
387 {
392 /* Check that -CST will not overflow type. */
405 /* We want to canonicalize to positive real constants. Pretend
406 that only negative ones can be easily negated. */
414 {
425 }
440 /* -(A + B) -> (-B) - A. */
445 /* -(A + B) -> (-A) - B. */
449 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
460 /* INT_MIN/n * n doesn't overflow while negating one operand it does
461 if n is a power of two. */
470 /* Fall through. */
485 /* In general we can't negate B in A / B, because if A is INT_MIN and
486 B is 1, we may turn this into INT_MIN / -1 which is undefined
487 and actually traps on some architectures. */
496 /* Negate -((double)float) as (double)(-float). */
498 {
502 }
506 /* Negate -f(x) as f(-x). */
512 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
514 {
518 }
523 }
525 }
527 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
528 simplification is possible.
529 If negate_expr_p would return true for T, NULL_TREE will never be
530 returned. */
532 static tree
534 {
536 tree tem;
539 {
540 /* Convert - (~A) to A + 1. */
566 {
571 }
575 {
580 {
584 }
587 }
610 {
611 /* -(A + B) -> (-B) - A. */
615 {
619 }
621 /* -(A + B) -> (-A) - B. */
623 {
627 }
628 }
632 /* - (A - B) -> B - A */
644 /* Fall through. */
648 {
657 }
669 /* In general we can't negate B in A / B, because if A is INT_MIN and
670 B is 1, we may turn this into INT_MIN / -1 which is undefined
671 and actually traps on some architectures. */
683 /* Convert -((double)float) into (double)(-float). */
685 {
689 }
693 /* Negate -f(x) as f(-x). */
696 {
702 }
706 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
708 {
711 {
718 }
719 }
724 }
727 }
729 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
730 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
731 return NULL_TREE. */
733 static tree
735 {
737 location_t loc;
750 }
751 \f
752 /* Split a tree IN into a constant, literal and variable parts that could be
753 combined with CODE to make IN. "constant" means an expression with
754 TREE_CONSTANT but that isn't an actual constant. CODE must be a
755 commutative arithmetic operation. Store the constant part into *CONP,
756 the literal in *LITP and return the variable part. If a part isn't
757 present, set it to null. If the tree does not decompose in this way,
758 return the entire tree as the variable part and the other parts as null.
760 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
761 case, we negate an operand that was subtracted. Except if it is a
762 literal for which we use *MINUS_LITP instead.
764 If NEGATE_P is true, we are negating all of IN, again except a literal
765 for which we use *MINUS_LITP instead. If a variable part is of pointer
766 type, it is negated after converting to TYPE. This prevents us from
767 generating illegal MINUS pointer expression. LOC is the location of
768 the converted variable part.
770 If IN is itself a literal or constant, return it as appropriate.
772 Note that we do not guarantee that any of the three values will be the
773 same type as IN, but they will have the same signedness and mode. */
775 static tree
778 {
785 /* Strip any conversions that don't change the machine mode or signedness. */
794 /* We can associate addition and subtraction together (even
795 though the C standard doesn't say so) for integers because
796 the value is not affected. For reals, the value might be
797 affected, so we can't. */
800 {
806 /* First see if either of the operands is a literal, then a constant. */
819 /* If we haven't dealt with either operand, this is not a case we can
820 decompose. Otherwise, VAR is either of the ones remaining, if any. */
825 else
828 /* Now do any needed negations. */
834 {
835 /* Convert to TYPE before negating. */
838 }
839 }
842 {
843 /* -X - 1 is folded to ~X, undo that here. */
846 }
849 else
853 {
860 {
861 /* Convert to TYPE before negating. */
864 }
865 }
868 }
870 /* Re-associate trees split by the above function. T1 and T2 are
871 either expressions to associate or null. Return the new
872 expression, if any. LOC is the location of the new expression. If
873 we build an operation, do it in TYPE and with CODE. */
875 static tree
877 {
883 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
884 try to fold this since we will have infinite recursion. But do
885 deal with any NEGATE_EXPRs. */
888 {
890 {
903 }
905 {
908 }
912 }
916 }
917 \f
918 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
919 for use in int_const_binop, size_binop and size_diffop. */
921 static bool
923 {
930 {
939 }
944 }
947 /* Combine two integer constants ARG1 and ARG2 under operation CODE
948 to produce a new constant. Return NULL_TREE if we don't know how
949 to evaluate CODE at compile-time. */
951 static tree
954 {
955 wide_int res;
956 tree t;
964 {
980 {
984 else
986 }
989 /* It's unclear from the C standard whether shifts can overflow.
990 The following code ignores overflow; perhaps a C standard
991 interpretation ruling is needed. */
993 else
1000 {
1004 else
1006 }
1010 else
1089 }
1097 }
1099 tree
1101 {
1103 }
1105 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1106 constant. We assume ARG1 and ARG2 have the same data type, or at least
1107 are the same kind of constant and the same machine mode. Return zero if
1108 combining the constants is not allowed in the current operating mode. */
1110 static tree
1112 {
1113 /* Sanity check for the recursive cases. */
1121 {
1127 }
1130 {
1131 machine_mode mode;
1132 REAL_VALUE_TYPE d1;
1133 REAL_VALUE_TYPE d2;
1134 REAL_VALUE_TYPE value;
1135 REAL_VALUE_TYPE result;
1139 /* The following codes are handled by real_arithmetic. */
1141 {
1152 }
1160 /* Don't perform operation if we honor signaling NaNs and
1161 either operand is a signaling NaN. */
1167 /* Don't perform operation if it would raise a division
1168 by zero exception. */
1174 /* If either operand is a NaN, just return it. Otherwise, set up
1175 for floating-point trap; we return an overflow. */
1177 {
1178 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1179 is off. */
1183 }
1185 {
1186 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1187 is off. */
1191 }
1196 /* Don't constant fold this floating point operation if
1197 the result has overflowed and flag_trapping_math. */
1205 /* Don't constant fold this floating point operation if the
1206 result may dependent upon the run-time rounding mode and
1207 flag_rounding_math is set, or if GCC's software emulation
1208 is unable to accurately represent the result. */
1218 }
1221 {
1222 FIXED_VALUE_TYPE f1;
1223 FIXED_VALUE_TYPE f2;
1224 FIXED_VALUE_TYPE result;
1229 /* The following codes are handled by fixed_arithmetic. */
1231 {
1243 {
1250 }
1255 }
1262 /* Propagate overflow flags. */
1266 }
1269 {
1278 {
1289 mpc_mul);
1303 mpc_div);
1304 /* Fallthru ... */
1310 {
1311 /* Keep this algorithm in sync with
1312 tree-complex.c:expand_complex_div_straight().
1314 Expand complex division to scalars, straightforward algorithm.
1315 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1316 t = br*br + bi*bi
1317 */
1318 tree magsquared
1322 tree t1
1326 tree t2
1333 }
1334 else
1335 {
1336 /* Keep this algorithm in sync with
1337 tree-complex.c:expand_complex_div_wide().
1339 Expand complex division to scalars, modified algorithm to minimize
1340 overflow with wide input ranges. */
1346 {
1347 /* In the TRUE branch, we compute
1348 ratio = br/bi;
1349 div = (br * ratio) + bi;
1350 tr = (ar * ratio) + ai;
1351 ti = (ai * ratio) - ar;
1352 tr = tr / div;
1353 ti = ti / div; */
1364 }
1365 else
1366 {
1367 /* In the FALSE branch, we compute
1368 ratio = d/c;
1369 divisor = (d * ratio) + c;
1370 tr = (b * ratio) + a;
1371 ti = b - (a * ratio);
1372 tr = tr / div;
1373 ti = ti / div; */
1385 }
1386 }
1391 }
1395 }
1399 {
1405 {
1411 /* It is possible that const_binop cannot handle the given
1412 code and return NULL_TREE */
1415 }
1418 }
1420 /* Shifts allow a scalar offset for a vector. */
1423 {
1429 {
1434 /* It is possible that const_binop cannot handle the given
1435 code and return NULL_TREE. */
1438 }
1441 }
1443 }
1445 /* Overload that adds a TYPE parameter to be able to dispatch
1446 to fold_relational_const. */
1448 tree
1450 {
1454 /* ??? Until we make the const_binop worker take the type of the
1455 result as argument put those cases that need it here. */
1457 {
1468 {
1484 {
1490 }
1493 }
1499 {
1524 {
1537 }
1540 }
1543 }
1548 /* Make sure type and arg0 have the same saturating flag. */
1553 }
1555 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1556 Return zero if computing the constants is not possible. */
1558 tree
1560 {
1561 /* Don't perform the operation, other than NEGATE and ABS, if
1562 flag_signaling_nans is on and the operand is a signaling NaN. */
1571 {
1572 CASE_CONVERT:
1579 /* If the source address is 0, and the source address space
1580 cannot have a valid object at 0, fold to dest type null. */
1591 {
1592 /* Can't call fold_negate_const directly here as that doesn't
1593 handle all cases and we might not be able to negate some
1594 constants. */
1599 }
1608 {
1612 }
1618 /* Perform BIT_NOT_EXPR on each element individually. */
1620 {
1622 tree elem;
1627 {
1633 }
1636 }
1658 {
1677 else
1681 {
1685 }
1688 }
1693 {
1707 {
1712 }
1715 {
1719 }
1722 }
1726 }
1729 }
1731 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1732 indicates which particular sizetype to create. */
1734 tree
1736 {
1738 }
1739 \f
1740 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1741 is a tree code. The type of the result is taken from the operands.
1742 Both must be equivalent integer types, ala int_binop_types_match_p.
1743 If the operands are constant, so is the result. */
1745 tree
1747 {
1756 /* Handle the special case of two integer constants faster. */
1758 {
1759 /* And some specific cases even faster than that. */
1761 {
1766 }
1768 {
1771 }
1773 {
1776 }
1778 /* Handle general case of two integer constants. For sizetype
1779 constant calculations we always want to know about overflow,
1780 even in the unsigned case. */
1782 }
1785 }
1787 /* Given two values, either both of sizetype or both of bitsizetype,
1788 compute the difference between the two values. Return the value
1789 in signed type corresponding to the type of the operands. */
1791 tree
1793 {
1795 tree ctype;
1800 /* If the type is already signed, just do the simple thing. */
1808 else
1811 /* If either operand is not a constant, do the conversions to the signed
1812 type and subtract. The hardware will do the right thing with any
1813 overflow in the subtraction. */
1819 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1820 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1821 overflow) and negate (which can't either). Special-case a result
1822 of zero while we're here. */
1828 else
1832 MINUS_EXPR,
1834 }
1835 \f
1836 /* A subroutine of fold_convert_const handling conversions of an
1837 INTEGER_CST to another integer type. */
1839 static tree
1841 {
1842 /* Given an integer constant, make new constant with new type,
1843 appropriately sign-extended or truncated. Use widest_int
1844 so that any extension is done according ARG1's type. */
1848 }
1850 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1851 to an integer type. */
1853 static tree
1855 {
1857 tree t;
1859 /* The following code implements the floating point to integer
1860 conversion rules required by the Java Language Specification,
1861 that IEEE NaNs are mapped to zero and values that overflow
1862 the target precision saturate, i.e. values greater than
1863 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1864 are mapped to INT_MIN. These semantics are allowed by the
1865 C and C++ standards that simply state that the behavior of
1866 FP-to-integer conversion is unspecified upon overflow. */
1868 wide_int val;
1869 REAL_VALUE_TYPE r;
1873 {
1880 }
1882 /* If R is NaN, return zero and show we have an overflow. */
1884 {
1887 }
1889 /* See if R is less than the lower bound or greater than the
1890 upper bound. */
1893 {
1897 {
1900 }
1901 }
1904 {
1907 {
1910 {
1913 }
1914 }
1915 }
1922 }
1924 /* A subroutine of fold_convert_const handling conversions of a
1925 FIXED_CST to an integer type. */
1927 static tree
1929 {
1930 tree t;
1934 /* Right shift FIXED_CST to temp by fbit. */
1938 {
1940 HOST_BITS_PER_DOUBLE_INT,
1943 /* Left shift temp to temp_trunc by fbit. */
1945 HOST_BITS_PER_DOUBLE_INT,
1947 }
1948 else
1949 {
1952 }
1954 /* If FIXED_CST is negative, we need to round the value toward 0.
1955 By checking if the fractional bits are not zero to add 1 to temp. */
1961 /* Given a fixed-point constant, make new constant with new type,
1962 appropriately sign-extended or truncated. */
1970 }
1972 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1973 to another floating point type. */
1975 static tree
1977 {
1978 REAL_VALUE_TYPE value;
1979 tree t;
1981 /* Don't perform the operation if flag_signaling_nans is on
1982 and the operand is a signaling NaN. */
1990 /* If converting an infinity or NAN to a representation that doesn't
1991 have one, set the overflow bit so that we can produce some kind of
1992 error message at the appropriate point if necessary. It's not the
1993 most user-friendly message, but it's better than nothing. */
2000 /* Regular overflow, conversion produced an infinity in a mode that
2001 can't represent them. */
2006 else
2009 }
2011 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2012 to a floating point type. */
2014 static tree
2016 {
2017 REAL_VALUE_TYPE value;
2018 tree t;
2025 }
2027 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2028 to another fixed-point type. */
2030 static tree
2032 {
2033 FIXED_VALUE_TYPE value;
2034 tree t;
2041 /* Propagate overflow flags. */
2045 }
2047 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2048 to a fixed-point type. */
2050 static tree
2052 {
2053 FIXED_VALUE_TYPE value;
2054 tree t;
2056 double_int di;
2063 else
2071 /* Propagate overflow flags. */
2075 }
2077 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2078 to a fixed-point type. */
2080 static tree
2082 {
2083 FIXED_VALUE_TYPE value;
2084 tree t;
2092 /* Propagate overflow flags. */
2096 }
2098 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2099 type TYPE. If no simplification can be done return NULL_TREE. */
2101 static tree
2103 {
2109 {
2116 }
2118 {
2125 }
2127 {
2134 }
2136 {
2139 {
2144 {
2150 }
2152 }
2153 }
2155 }
2157 /* Construct a vector of zero elements of vector type TYPE. */
2159 static tree
2161 {
2162 tree t;
2166 }
2168 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2170 bool
2172 {
2187 {
2203 }
2204 }
2206 /* Convert expression ARG to type TYPE. Used by the middle-end for
2207 simple conversions in preference to calling the front-end's convert. */
2209 tree
2211 {
2213 tree tem;
2224 {
2227 /* Handle conversions between pointers to different address spaces. */
2232 /* fall through */
2237 {
2241 }
2255 {
2259 }
2261 {
2265 }
2267 {
2271 }
2274 {
2292 }
2297 {
2301 }
2304 {
2318 }
2322 {
2331 integer_zero_node));
2333 {
2337 {
2343 }
2351 }
2355 }
2373 }
2374 fold_convert_exit:
2377 }
2378 \f
2379 /* Return false if expr can be assumed not to be an lvalue, true
2380 otherwise. */
2382 static bool
2384 {
2385 /* We only need to wrap lvalue tree codes. */
2387 {
2418 /* Assume the worst for front-end tree codes. */
2422 }
2425 }
2427 /* Return an expr equal to X but certainly not valid as an lvalue. */
2429 tree
2431 {
2432 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2433 us. */
2440 }
2442 /* When pedantic, return an expr equal to X but certainly not valid as a
2443 pedantic lvalue. Otherwise, return X. */
2445 static tree
2447 {
2449 }
2450 \f
2451 /* Given a tree comparison code, return the code that is the logical inverse.
2452 It is generally not safe to do this for floating-point comparisons, except
2453 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2454 ERROR_MARK in this case. */
2456 enum tree_code
2458 {
2464 {
2495 }
2496 }
2498 /* Similar, but return the comparison that results if the operands are
2499 swapped. This is safe for floating-point. */
2501 enum tree_code
2503 {
2505 {
2531 }
2532 }
2535 /* Convert a comparison tree code from an enum tree_code representation
2536 into a compcode bit-based encoding. This function is the inverse of
2537 compcode_to_comparison. */
2539 static enum comparison_code
2541 {
2543 {
2574 }
2575 }
2577 /* Convert a compcode bit-based encoding of a comparison operator back
2578 to GCC's enum tree_code representation. This function is the
2579 inverse of comparison_to_compcode. */
2581 static enum tree_code
2583 {
2585 {
2616 }
2617 }
2619 /* Return a tree for the comparison which is the combination of
2620 doing the AND or OR (depending on CODE) of the two operations LCODE
2621 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2622 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2623 if this makes the transformation invalid. */
2625 tree
2630 {
2637 {
2648 }
2651 {
2652 /* Eliminate unordered comparisons, as well as LTGT and ORD
2653 which are not used unless the mode has NaNs. */
2659 }
2661 {
2662 /* Check that the original operation and the optimized ones will trap
2663 under the same condition. */
2674 /* In a short-circuited boolean expression the LHS might be
2675 such that the RHS, if evaluated, will never trap. For
2676 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2677 if neither x nor y is NaN. (This is a mixed blessing: for
2678 example, the expression above will never trap, hence
2679 optimizing it to x < y would be invalid). */
2684 /* If the comparison was short-circuited, and only the RHS
2685 trapped, we may now generate a spurious trap. */
2690 /* If we changed the conditions that cause a trap, we lose. */
2693 }
2699 else
2700 {
2705 }
2706 }
2707 \f
2708 /* Return nonzero if two operands (typically of the same tree node)
2709 are necessarily equal. FLAGS modifies behavior as follows:
2711 If OEP_ONLY_CONST is set, only return nonzero for constants.
2712 This function tests whether the operands are indistinguishable;
2713 it does not test whether they are equal using C's == operation.
2714 The distinction is important for IEEE floating point, because
2715 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2716 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2718 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2719 even though it may hold multiple values during a function.
2720 This is because a GCC tree node guarantees that nothing else is
2721 executed between the evaluation of its "operands" (which may often
2722 be evaluated in arbitrary order). Hence if the operands themselves
2723 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2724 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2725 unset means assuming isochronic (or instantaneous) tree equivalence.
2726 Unless comparing arbitrary expression trees, such as from different
2727 statements, this flag can usually be left unset.
2729 If OEP_PURE_SAME is set, then pure functions with identical arguments
2730 are considered the same. It is used when the caller has other ways
2731 to ensure that global memory is unchanged in between.
2733 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2734 not values of expressions.
2736 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2737 any operand with side effect. This is unnecesarily conservative in the
2738 case we know that arg0 and arg1 are in disjoint code paths (such as in
2739 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2740 addresses with TREE_CONSTANT flag set so we know that &var == &var
2741 even if var is volatile. */
2743 int
2745 {
2746 /* When checking, verify at the outermost operand_equal_p call that
2747 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2748 hash value. */
2750 {
2752 {
2754 {
2761 }
2763 }
2764 else
2766 }
2768 /* If either is ERROR_MARK, they aren't equal. */
2774 /* Similar, if either does not have a type (like a released SSA name),
2775 they aren't equal. */
2779 /* We cannot consider pointers to different address space equal. */
2786 /* Check equality of integer constants before bailing out due to
2787 precision differences. */
2789 {
2790 /* Address of INTEGER_CST is not defined; check that we did not forget
2791 to drop the OEP_ADDRESS_OF flags. */
2794 }
2797 {
2798 /* If both types don't have the same signedness, then we can't consider
2799 them equal. We must check this before the STRIP_NOPS calls
2800 because they may change the signedness of the arguments. As pointers
2801 strictly don't have a signedness, require either two pointers or
2802 two non-pointers as well. */
2808 /* If both types don't have the same precision, then it is not safe
2809 to strip NOPs. */
2816 }
2817 #if 0
2818 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2819 sanity check once the issue is solved. */
2820 else
2821 /* Addresses of conversions and SSA_NAMEs (and many other things)
2822 are not defined. Check that we did not forget to drop the
2823 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2826 #endif
2828 /* In case both args are comparisons but with different comparison
2829 code, try to swap the comparison operands of one arg to produce
2830 a match and compare that variant. */
2834 {
2842 }
2845 {
2846 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2848 ;
2850 {
2851 /* If we are interested in comparing addresses ignore
2852 MEM_REF wrappings of the base that can appear just for
2853 TBAA reasons. */
2867 }
2868 else
2870 }
2872 /* When not checking adddresses, this is needed for conversions and for
2873 COMPONENT_REF. Might as well play it safe and always test this. */
2880 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2881 We don't care about side effects in that case because the SAVE_EXPR
2882 takes care of that for us. In all other cases, two expressions are
2883 equal if they have no side effects. If we have two identical
2884 expressions with side effects that should be treated the same due
2885 to the only side effects being identical SAVE_EXPR's, that will
2886 be detected in the recursive calls below.
2887 If we are taking an invariant address of two identical objects
2888 they are necessarily equal as well. */
2895 /* Next handle constant cases, those for which we can return 1 even
2896 if ONLY_CONST is set. */
2899 {
2913 {
2914 /* If we do not distinguish between signed and unsigned zero,
2915 consider them equal. */
2918 }
2922 {
2929 {
2933 }
2935 }
2939 flags)
2941 flags));
2952 flags | OEP_ADDRESS_OF
2955 /* In GIMPLE empty constructors are allowed in initializers of
2956 aggregates. */
2961 }
2966 /* Define macros to test an operand from arg0 and arg1 for equality and a
2967 variant that allows null and views null as being different from any
2968 non-null value. In the latter case, if either is null, the both
2969 must be; otherwise, do the normal comparison. */
2970 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2971 TREE_OPERAND (arg1, N), flags)
2973 #define OP_SAME_WITH_NULL(N) \
2974 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2975 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2978 {
2980 /* Two conversions are equal only if signedness and modes match. */
2982 {
2983 CASE_CONVERT:
2991 }
3001 /* For commutative ops, allow the other order. */
3009 /* If either of the pointer (or reference) expressions we are
3010 dereferencing contain a side effect, these cannot be equal,
3011 but their addresses can be. */
3018 {
3028 /* Require the same offset. */
3034 /* Fallthru. */
3042 {
3043 /* Require equal access sizes */
3049 flags)))
3051 /* Verify that access happens in similar types. */
3054 /* Verify that accesses are TBAA compatible. */
3063 /* Verify that alignment is compatible. */
3067 }
3070 /* TARGET_MEM_REF require equal extra operands. */
3081 /* Compare the array index by value if it is constant first as we
3082 may have different types but same value here. */
3088 /* Compare low bound and element size as with OEP_ADDRESS_OF
3089 we have to account for the offset of the ref. */
3094 array_ref_low_bound
3098 array_ref_element_size
3100 flags))));
3103 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3104 may be NULL when we're called to compare MEM_EXPRs. */
3119 }
3123 {
3125 /* Be sure we pass right ADDRESS_OF flag. */
3143 /* The multiplcation operands are commutative. */
3144 /* FALLTHRU */
3152 /* Otherwise take into account this is a commutative operation. */
3171 }
3175 {
3179 /* If not both CALL_EXPRs are either internal or normal function
3180 functions, then they are not equal. */
3183 {
3184 /* If the CALL_EXPRs call different internal functions, then they
3185 are not equal. */
3188 }
3189 else
3190 {
3191 /* If the CALL_EXPRs call different functions, then they are not
3192 equal. */
3194 flags))
3196 }
3198 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3199 {
3203 else
3207 }
3209 /* Now see if all the arguments are the same. */
3210 {
3221 /* If we get here and both argument lists are exhausted
3222 then the CALL_EXPRs are equal. */
3224 }
3227 }
3230 /* Consider __builtin_sqrt equal to sqrt. */
3238 {
3239 /* In GIMPLE constructors are used only to build vectors from
3240 elements. Individual elements in the constructor must be
3241 indexed in increasing order and form an initial sequence.
3243 We make no effort to compare constructors in generic.
3244 (see sem_variable::equals in ipa-icf which can do so for
3245 constants). */
3250 /* Be sure that vectors constructed have the same representation.
3251 We only tested element precision and modes to match.
3252 Vectors may be BLKmode and thus also check that the number of
3253 parts match. */
3266 {
3271 /* In GIMPLE the indexes can be either NULL or matching i.
3272 Double check this so we won't get false
3273 positives for GENERIC. */
3281 }
3283 }
3288 }
3290 #undef OP_SAME
3291 #undef OP_SAME_WITH_NULL
3292 }
3293 \f
3294 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3295 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3297 When in doubt, return 0. */
3299 static int
3301 {
3313 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3314 and see if the inner values are the same. This removes any
3315 signedness comparison, which doesn't matter here. */
3322 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3323 actual comparison operand, ARG0.
3325 First throw away any conversions to wider types
3326 already present in the operands. */
3335 {
3338 /* Make sure shorter operand is extended the right way
3339 to match the longer operand. */
3345 }
3348 }
3349 \f
3350 /* See if ARG is an expression that is either a comparison or is performing
3351 arithmetic on comparisons. The comparisons must only be comparing
3352 two different values, which will be stored in *CVAL1 and *CVAL2; if
3353 they are nonzero it means that some operands have already been found.
3354 No variables may be used anywhere else in the expression except in the
3355 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3356 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3358 If this is true, return 1. Otherwise, return zero. */
3360 static int
3362 {
3366 /* We can handle some of the tcc_expression cases here. */
3376 {
3377 /* If we've already found a CVAL1 or CVAL2, this expression is
3378 two complex to handle. */
3384 }
3387 {
3410 /* First see if we can handle the first operand, then the second. For
3411 the second operand, we know *CVAL1 can't be zero. It must be that
3412 one side of the comparison is each of the values; test for the
3413 case where this isn't true by failing if the two operands
3414 are the same. */
3423 ;
3427 ;
3428 else
3432 ;
3436 ;
3437 else
3444 }
3445 }
3446 \f
3447 /* ARG is a tree that is known to contain just arithmetic operations and
3448 comparisons. Evaluate the operations in the tree substituting NEW0 for
3449 any occurrence of OLD0 as an operand of a comparison and likewise for
3450 NEW1 and OLD1. */
3452 static tree
3455 {
3460 /* We can handle some of the tcc_expression cases here. */
3468 {
3483 {
3502 }
3503 /* Fall through - ??? */
3506 {
3510 /* We need to check both for exact equality and tree equality. The
3511 former will be true if the operand has a side-effect. In that
3512 case, we know the operand occurred exactly once. */
3525 }
3529 }
3530 }
3531 \f
3532 /* Return a tree for the case when the result of an expression is RESULT
3533 converted to TYPE and OMITTED was previously an operand of the expression
3534 but is now not needed (e.g., we folded OMITTED * 0).
3536 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3537 the conversion of RESULT to TYPE. */
3539 tree
3541 {
3544 /* If the resulting operand is an empty statement, just return the omitted
3545 statement casted to void. */
3555 }
3557 /* Return a tree for the case when the result of an expression is RESULT
3558 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3559 of the expression but are now not needed.
3561 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3562 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3563 evaluated before OMITTED2. Otherwise, if neither has side effects,
3564 just do the conversion of RESULT to TYPE. */
3566 tree
3569 {
3578 }
3580 \f
3581 /* Return a simplified tree node for the truth-negation of ARG. This
3582 never alters ARG itself. We assume that ARG is an operation that
3583 returns a truth value (0 or 1).
3585 FIXME: one would think we would fold the result, but it causes
3586 problems with the dominator optimizer. */
3588 static tree
3590 {
3595 /* If this is a comparison, we can simply invert it, except for
3596 floating-point non-equality comparisons, in which case we just
3597 enclose a TRUTH_NOT_EXPR around what we have. */
3600 {
3603 && flag_trapping_math
3617 }
3620 {
3639 /* Here we can invert either operand. We invert the first operand
3640 unless the second operand is a TRUTH_NOT_EXPR in which case our
3641 result is the XOR of the first operand with the inside of the
3642 negation of the second operand. */
3647 else
3670 {
3677 /* A COND_EXPR may have a throw as one operand, which
3678 then has void type. Just leave void operands
3679 as they are. */
3685 }
3697 CASE_CONVERT:
3701 /* ... fall through ... */
3723 }
3724 }
3726 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3727 assume that ARG is an operation that returns a truth value (0 or 1
3728 for scalars, 0 or -1 for vectors). Return the folded expression if
3729 folding is successful. Otherwise, return NULL_TREE. */
3731 static tree
3733 {
3736 ? BIT_NOT_EXPR
3739 }
3741 /* Return a simplified tree node for the truth-negation of ARG. This
3742 never alters ARG itself. We assume that ARG is an operation that
3743 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3745 tree
3747 {
3753 ? BIT_NOT_EXPR
3756 }
3758 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3759 with code CODE. This optimization is unsafe. */
3760 static tree
3763 {
3767 /* (A / C) +- (B / C) -> (A +- B) / C. */
3777 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3782 {
3794 }
3797 }
3798 \f
3799 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3800 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3801 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3802 is the original memory reference used to preserve the alias set of
3803 the access. */
3805 static tree
3809 {
3815 build_int_cst
3819 {
3826 }
3841 }
3843 /* Optimize a bit-field compare.
3845 There are two cases: First is a compare against a constant and the
3846 second is a comparison of two items where the fields are at the same
3847 bit position relative to the start of a chunk (byte, halfword, word)
3848 large enough to contain it. In these cases we can avoid the shift
3849 implicit in bitfield extractions.
3851 For constants, we emit a compare of the shifted constant with the
3852 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3853 compared. For two fields at the same position, we do the ANDs with the
3854 similar mask and compare the result of the ANDs.
3856 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3857 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3858 are the left and right operands of the comparison, respectively.
3860 If the optimization described above can be done, we return the resulting
3861 tree. Otherwise we return zero. */
3863 static tree
3866 {
3869 tree unsigned_type;
3876 tree mask;
3877 tree offset;
3879 /* Get all the information about the extractions being done. If the bit size
3880 if the same as the size of the underlying object, we aren't doing an
3881 extraction at all and so can do nothing. We also don't want to
3882 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3883 then will no longer be able to replace it. */
3892 else
3893 {
3894 /* If this is not a constant, we can only do something if bit positions,
3895 sizes, signedness and storage order are the same. */
3896 rinner
3904 }
3906 /* See if we can find a mode to refer to this field. We should be able to,
3907 but fail if we can't. */
3916 /* Set signed and unsigned types of the precision of this mode for the
3917 shifts below. */
3920 /* Compute the bit position and size for the new reference and our offset
3921 within it. If the new reference is the same size as the original, we
3922 won't optimize anything, so return zero. */
3932 /* Make the mask to be used against the extracted field. */
3939 /* If not comparing with constant, just rework the comparison
3940 and return. */
3944 unsigned_type,
3947 mask),
3950 unsigned_type,
3953 mask));
3955 /* Otherwise, we are handling the constant case. See if the constant is too
3956 big for the field. Warn and return a tree for 0 (false) if so. We do
3957 this not only for its own sake, but to avoid having to test for this
3958 error case below. If we didn't, we might generate wrong code.
3960 For unsigned fields, the constant shifted right by the field length should
3961 be all zero. For signed fields, the high-order bits should agree with
3962 the sign bit. */
3965 {
3967 {
3971 }
3972 }
3973 else
3974 {
3977 {
3981 }
3982 }
3984 /* Single-bit compares should always be against zero. */
3986 {
3989 }
3991 /* Make a new bitfield reference, shift the constant over the
3992 appropriate number of bits and mask it with the computed mask
3993 (in case this was a signed field). If we changed it, make a new one. */
4001 mask);
4006 }
4007 \f
4008 /* Subroutine for fold_truth_andor_1: decode a field reference.
4010 If EXP is a comparison reference, we return the innermost reference.
4012 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4013 set to the starting bit number.
4015 If the innermost field can be completely contained in a mode-sized
4016 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4018 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4019 otherwise it is not changed.
4021 *PUNSIGNEDP is set to the signedness of the field.
4023 *PREVERSEP is set to the storage order of the field.
4025 *PMASK is set to the mask used. This is either contained in a
4026 BIT_AND_EXPR or derived from the width of the field.
4028 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4030 Return 0 if this is not a component reference or is one that we can't
4031 do anything with. */
4033 static tree
4038 {
4043 tree unsigned_type;
4046 /* All the optimizations using this function assume integer fields.
4047 There are problems with FP fields since the type_for_size call
4048 below can fail for, e.g., XFmode. */
4052 /* We are interested in the bare arrangement of bits, so strip everything
4053 that doesn't affect the machine mode. However, record the type of the
4054 outermost expression if it may matter below. */
4061 {
4067 }
4078 /* If the number of bits in the reference is the same as the bitsize of
4079 the outer type, then the outer type gives the signedness. Otherwise
4080 (in case of a small bitfield) the signedness is unchanged. */
4084 /* Compute the mask to access the bitfield. */
4093 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4101 }
4103 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4104 bit positions and MASK is SIGNED. */
4106 static int
4108 {
4112 /* If this function returns true when the type of the mask is
4113 UNSIGNED, then there will be errors. In particular see
4114 gcc.c-torture/execute/990326-1.c. There does not appear to be
4115 any documentation paper trail as to why this is so. But the pre
4116 wide-int worked with that restriction and it has been preserved
4117 here. */
4122 }
4124 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4125 represents the sign bit of EXP's type. If EXP represents a sign
4126 or zero extension, also test VAL against the unextended type.
4127 The return value is the (sub)expression whose sign bit is VAL,
4128 or NULL_TREE otherwise. */
4130 tree
4132 {
4134 tree t;
4136 /* Tree EXP must have an integral type. */
4141 /* Tree VAL must be an integer constant. */
4150 /* Handle extension from a narrower type. */
4156 }
4158 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4159 to be evaluated unconditionally. */
4161 static int
4163 {
4164 /* Strip any conversions that don't change the machine mode. */
4173 /* Don't regard global variables as simple. They may be
4174 allocated in ways unknown to the compiler (shared memory,
4175 #pragma weak, etc). */
4178 /* Weakrefs are not safe to be read, since they can be NULL.
4179 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4180 have DECL_WEAK flag set. */
4182 /* Loading a static variable is unduly expensive, but global
4183 registers aren't expensive. */
4185 }
4187 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4188 to be evaluated unconditionally.
4189 I addition to simple_operand_p, we assume that comparisons, conversions,
4190 and logic-not operations are simple, if their operands are simple, too. */
4192 static bool
4194 {
4214 }
4216 \f
4217 /* The following functions are subroutines to fold_range_test and allow it to
4218 try to change a logical combination of comparisons into a range test.
4220 For example, both
4221 X == 2 || X == 3 || X == 4 || X == 5
4222 and
4223 X >= 2 && X <= 5
4224 are converted to
4225 (unsigned) (X - 2) <= 3
4227 We describe each set of comparisons as being either inside or outside
4228 a range, using a variable named like IN_P, and then describe the
4229 range with a lower and upper bound. If one of the bounds is omitted,
4230 it represents either the highest or lowest value of the type.
4232 In the comments below, we represent a range by two numbers in brackets
4233 preceded by a "+" to designate being inside that range, or a "-" to
4234 designate being outside that range, so the condition can be inverted by
4235 flipping the prefix. An omitted bound is represented by a "-". For
4236 example, "- [-, 10]" means being outside the range starting at the lowest
4237 possible value and ending at 10, in other words, being greater than 10.
4238 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4239 always false.
4241 We set up things so that the missing bounds are handled in a consistent
4242 manner so neither a missing bound nor "true" and "false" need to be
4243 handled using a special case. */
4245 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4246 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4247 and UPPER1_P are nonzero if the respective argument is an upper bound
4248 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4249 must be specified for a comparison. ARG1 will be converted to ARG0's
4250 type if both are specified. */
4252 static tree
4255 {
4256 tree tem;
4260 /* If neither arg represents infinity, do the normal operation.
4261 Else, if not a comparison, return infinity. Else handle the special
4262 comparison rules. Note that most of the cases below won't occur, but
4263 are handled for consistency. */
4266 {
4271 }
4276 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4277 for neither. In real maths, we cannot assume open ended ranges are
4278 the same. But, this is computer arithmetic, where numbers are finite.
4279 We can therefore make the transformation of any unbounded range with
4280 the value Z, Z being greater than any representable number. This permits
4281 us to treat unbounded ranges as equal. */
4285 {
4306 }
4309 }
4310 \f
4311 /* Helper routine for make_range. Perform one step for it, return
4312 new expression if the loop should continue or NULL_TREE if it should
4313 stop. */
4315 tree
4319 {
4325 {
4327 /* We can only do something if the range is testing for zero. */
4336 /* We can only do something if the range is testing for zero
4337 and if the second operand is an integer constant. Note that
4338 saying something is "in" the range we make is done by
4339 complementing IN_P since it will set in the initial case of
4340 being not equal to zero; "out" is leaving it alone. */
4347 {
4368 }
4370 /* If this is an unsigned comparison, we also know that EXP is
4371 greater than or equal to zero. We base the range tests we make
4372 on that fact, so we record it here so we can parse existing
4373 range tests. We test arg0_type since often the return type
4374 of, e.g. EQ_EXPR, is boolean. */
4376 {
4380 NULL_TREE))
4385 /* If the high bound is missing, but we have a nonzero low
4386 bound, reverse the range so it goes from zero to the low bound
4387 minus 1. */
4389 {
4394 }
4395 }
4403 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4404 low and high are non-NULL, then normalize will DTRT. */
4407 {
4412 }
4414 /* (-x) IN [a,b] -> x in [-b, -a] */
4426 /* ~ X -> -X - 1 */
4435 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4436 move a constant to the other side. */
4441 /* If EXP is signed, any overflow in the computation is undefined,
4442 so we don't worry about it so long as our computations on
4443 the bounds don't overflow. For unsigned, overflow is defined
4444 and this is exactly the right thing. */
4456 normalize:
4457 /* Check for an unsigned range which has wrapped around the maximum
4458 value thus making n_high < n_low, and normalize it. */
4460 {
4466 /* If the range is of the form +/- [ x+1, x ], we won't
4467 be able to normalize it. But then, it represents the
4468 whole range or the empty set, so make it
4469 +/- [ -, - ]. */
4473 else
4475 }
4476 else
4484 CASE_CONVERT:
4502 /* If we're converting arg0 from an unsigned type, to exp,
4503 a signed type, we will be doing the comparison as unsigned.
4504 The tests above have already verified that LOW and HIGH
4505 are both positive.
4507 So we have to ensure that we will handle large unsigned
4508 values the same way that the current signed bounds treat
4509 negative values. */
4512 {
4513 tree high_positive;
4514 tree equiv_type;
4515 /* For fixed-point modes, we need to pass the saturating flag
4516 as the 2nd parameter. */
4518 equiv_type
4521 else
4522 equiv_type
4525 /* A range without an upper bound is, naturally, unbounded.
4526 Since convert would have cropped a very large value, use
4527 the max value for the destination type. */
4528 high_positive
4535 high_positive),
4538 /* If the low bound is specified, "and" the range with the
4539 range for which the original unsigned value will be
4540 positive. */
4542 {
4545 integer_zero_node),
4546 high_positive))
4550 }
4551 else
4552 {
4553 /* Otherwise, "or" the range with the range of the input
4554 that will be interpreted as negative. */
4557 integer_zero_node),
4558 high_positive))
4562 }
4563 }
4572 }
4573 }
4575 /* Given EXP, a logical expression, set the range it is testing into
4576 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4577 actually being tested. *PLOW and *PHIGH will be made of the same
4578 type as the returned expression. If EXP is not a comparison, we
4579 will most likely not be returning a useful value and range. Set
4580 *STRICT_OVERFLOW_P to true if the return value is only valid
4581 because signed overflow is undefined; otherwise, do not change
4582 *STRICT_OVERFLOW_P. */
4584 tree
4587 {
4595 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4596 and see if we can refine the range. Some of the cases below may not
4597 happen, but it doesn't seem worth worrying about this. We "continue"
4598 the outer loop when we've changed something; otherwise we "break"
4599 the switch, which will "break" the while. */
4605 {
4611 {
4619 }
4628 }
4630 /* If EXP is a constant, we can evaluate whether this is true or false. */
4632 {
4639 }
4643 }
4644 \f
4645 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4646 type, TYPE, return an expression to test if EXP is in (or out of, depending
4647 on IN_P) the range. Return 0 if the test couldn't be created. */
4649 tree
4652 {
4655 /* Disable this optimization for function pointer expressions
4656 on targets that require function pointer canonicalization. */
4663 {
4669 }
4687 {
4689 {
4693 }
4695 }
4697 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4699 {
4703 {
4705 {
4708 etype
4710 else
4713 }
4716 }
4717 }
4719 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4720 This requires wrap-around arithmetics for the type of the expression.
4721 First make sure that arithmetics in this type is valid, then make sure
4722 that it wraps around. */
4728 {
4731 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4732 for the type in question, as we rely on this here. */
4742 else
4744 }
4754 {
4756 {
4761 }
4763 }
4771 }
4772 \f
4773 /* Return the predecessor of VAL in its type, handling the infinite case. */
4775 static tree
4777 {
4783 else
4786 }
4788 /* Return the successor of VAL in its type, handling the infinite case. */
4790 static tree
4792 {
4798 else
4801 }
4803 /* Given two ranges, see if we can merge them into one. Return 1 if we
4804 can, 0 if we can't. Set the output range into the specified parameters. */
4806 bool
4809 {
4813 tree tem;
4823 /* Make range 0 be the range that starts first, or ends last if they
4824 start at the same value. Swap them if it isn't. */
4827 || (lowequal
4830 {
4834 }
4836 /* Now flag two cases, whether the ranges are disjoint or whether the
4837 second range is totally subsumed in the first. Note that the tests
4838 below are simplified by the ones above. */
4844 /* We now have four cases, depending on whether we are including or
4845 excluding the two ranges. */
4847 {
4848 /* If they don't overlap, the result is false. If the second range
4849 is a subset it is the result. Otherwise, the range is from the start
4850 of the second to the end of the first. */
4855 else
4857 }
4860 {
4861 /* If they don't overlap, the result is the first range. If they are
4862 equal, the result is false. If the second range is a subset of the
4863 first, and the ranges begin at the same place, we go from just after
4864 the end of the second range to the end of the first. If the second
4865 range is not a subset of the first, or if it is a subset and both
4866 ranges end at the same place, the range starts at the start of the
4867 first range and ends just before the second range.
4868 Otherwise, we can't describe this as a single range. */
4874 {
4879 {
4880 /* We are in the weird situation where high0 > high1 but
4881 high1 has no successor. Punt. */
4883 }
4884 }
4886 {
4891 {
4892 /* low0 < low1 but low1 has no predecessor. Punt. */
4894 }
4895 }
4896 else
4898 }
4901 {
4902 /* If they don't overlap, the result is the second range. If the second
4903 is a subset of the first, the result is false. Otherwise,
4904 the range starts just after the first range and ends at the
4905 end of the second. */
4910 else
4911 {
4916 {
4917 /* high1 > high0 but high0 has no successor. Punt. */
4919 }
4920 }
4921 }
4923 else
4924 {
4925 /* The case where we are excluding both ranges. Here the complex case
4926 is if they don't overlap. In that case, the only time we have a
4927 range is if they are adjacent. If the second is a subset of the
4928 first, the result is the first. Otherwise, the range to exclude
4929 starts at the beginning of the first range and ends at the end of the
4930 second. */
4932 {
4937 else
4938 {
4939 /* Canonicalize - [min, x] into - [-, x]. */
4942 {
4947 /* FALLTHROUGH */
4960 }
4962 /* Canonicalize - [x, max] into - [x, -]. */
4965 {
4970 /* FALLTHROUGH */
4986 }
4988 /* The ranges might be also adjacent between the maximum and
4989 minimum values of the given type. For
4990 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4991 return + [x + 1, y - 1]. */
4993 {
5000 }
5001 else
5003 }
5004 }
5007 else
5009 }
5013 }
5014 \f
5016 /* Subroutine of fold, looking inside expressions of the form
5017 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5018 of the COND_EXPR. This function is being used also to optimize
5019 A op B ? C : A, by reversing the comparison first.
5021 Return a folded expression whose code is not a COND_EXPR
5022 anymore, or NULL_TREE if no folding opportunity is found. */
5024 static tree
5027 {
5032 tree tem;
5037 /* If we have A op 0 ? A : -A, consider applying the following
5038 transformations:
5040 A == 0? A : -A same as -A
5041 A != 0? A : -A same as A
5042 A >= 0? A : -A same as abs (A)
5043 A > 0? A : -A same as abs (A)
5044 A <= 0? A : -A same as -abs (A)
5045 A < 0? A : -A same as -abs (A)
5047 None of these transformations work for modes with signed
5048 zeros. If A is +/-0, the first two transformations will
5049 change the sign of the result (from +0 to -0, or vice
5050 versa). The last four will fix the sign of the result,
5051 even though the original expressions could be positive or
5052 negative, depending on the sign of A.
5054 Note that all these transformations are correct if A is
5055 NaN, since the two alternatives (A and -A) are also NaNs. */
5062 /* In the case that A is of the form X-Y, '-A' (arg2) may
5063 have already been folded to Y-X, check for that. */
5071 {
5085 /* Fall through. */
5105 }
5107 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5108 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5109 both transformations are correct when A is NaN: A != 0
5110 is then true, and A == 0 is false. */
5114 {
5119 }
5121 /* Try some transformations of A op B ? A : B.
5123 A == B? A : B same as B
5124 A != B? A : B same as A
5125 A >= B? A : B same as max (A, B)
5126 A > B? A : B same as max (B, A)
5127 A <= B? A : B same as min (A, B)
5128 A < B? A : B same as min (B, A)
5130 As above, these transformations don't work in the presence
5131 of signed zeros. For example, if A and B are zeros of
5132 opposite sign, the first two transformations will change
5133 the sign of the result. In the last four, the original
5134 expressions give different results for (A=+0, B=-0) and
5135 (A=-0, B=+0), but the transformed expressions do not.
5137 The first two transformations are correct if either A or B
5138 is a NaN. In the first transformation, the condition will
5139 be false, and B will indeed be chosen. In the case of the
5140 second transformation, the condition A != B will be true,
5141 and A will be chosen.
5143 The conversions to max() and min() are not correct if B is
5144 a number and A is not. The conditions in the original
5145 expressions will be false, so all four give B. The min()
5146 and max() versions would give a NaN instead. */
5149 /* Avoid these transformations if the COND_EXPR may be used
5150 as an lvalue in the C++ front-end. PR c++/19199. */
5151 && (in_gimple_form
5157 {
5162 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5164 {
5168 }
5171 {
5180 /* In C++ a ?: expression can be an lvalue, so put the
5181 operand which will be used if they are equal first
5182 so that we can convert this back to the
5183 corresponding COND_EXPR. */
5185 {
5194 }
5201 {
5210 }
5225 }
5226 }
5228 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5229 we might still be able to simplify this. For example,
5230 if C1 is one less or one more than C2, this might have started
5231 out as a MIN or MAX and been transformed by this function.
5232 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5238 {
5242 /* We can replace A with C1 in this case. */
5247 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5248 MIN_EXPR, to preserve the signedness of the comparison. */
5250 OEP_ONLY_CONST)
5254 OEP_ONLY_CONST))
5255 {
5258 arg2));
5261 }
5265 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5266 as above. */
5268 OEP_ONLY_CONST)
5272 OEP_ONLY_CONST))
5273 {
5276 arg2));
5279 }
5283 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5284 MAX_EXPR, to preserve the signedness of the comparison. */
5286 OEP_ONLY_CONST)
5290 OEP_ONLY_CONST))
5291 {
5294 arg2));
5296 }
5300 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5302 OEP_ONLY_CONST)
5306 OEP_ONLY_CONST))
5307 {
5310 arg2));
5312 }
5318 }
5321 }
5324 \f
5325 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5326 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5327 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5328 false) >= 2)
5329 #endif
5331 /* EXP is some logical combination of boolean tests. See if we can
5332 merge it into some range test. Return the new tree if so. */
5334 static tree
5337 {
5353 /* If this is an OR operation, invert both sides; we will invert
5354 again at the end. */
5358 /* If both expressions are the same, if we can merge the ranges, and we
5359 can build the range test, return it or it inverted. If one of the
5360 ranges is always true or always false, consider it to be the same
5361 expression as the other. */
5369 {
5373 }
5375 /* On machines where the branch cost is expensive, if this is a
5376 short-circuited branch and the underlying object on both sides
5377 is the same, make a non-short-circuit operation. */
5383 {
5384 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5385 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5386 which cases we can't do this. */
5394 {
5403 {
5406 WARN_STRICT_OVERFLOW_COMPARISON);
5410 }
5411 }
5412 }
5415 }
5416 \f
5417 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5418 bit value. Arrange things so the extra bits will be set to zero if and
5419 only if C is signed-extended to its full width. If MASK is nonzero,
5420 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5422 static tree
5424 {
5427 tree temp;
5432 /* We work by getting just the sign bit into the low-order bit, then
5433 into the high-order bit, then sign-extend. We then XOR that value
5434 with C. */
5437 /* We must use a signed type in order to get an arithmetic right shift.
5438 However, we must also avoid introducing accidental overflows, so that
5439 a subsequent call to integer_zerop will work. Hence we must
5440 do the type conversion here. At this point, the constant is either
5441 zero or one, and the conversion to a signed type can never overflow.
5442 We could get an overflow if this conversion is done anywhere else. */
5451 /* If necessary, convert the type back to match the type of C. */
5456 }
5457 \f
5458 /* For an expression that has the form
5459 (A && B) || ~B
5460 or
5461 (A || B) && ~B,
5462 we can drop one of the inner expressions and simplify to
5463 A || ~B
5464 or
5465 A && ~B
5466 LOC is the location of the resulting expression. OP is the inner
5467 logical operation; the left-hand side in the examples above, while CMPOP
5468 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5469 removing a condition that guards another, as in
5470 (A != NULL && A->...) || A == NULL
5471 which we must not transform. If RHS_ONLY is true, only eliminate the
5472 right-most operand of the inner logical operation. */
5474 static tree
5477 {
5495 {
5498 {
5501 }
5502 }
5504 {
5507 {
5510 }
5511 }
5526 }
5528 /* Find ways of folding logical expressions of LHS and RHS:
5529 Try to merge two comparisons to the same innermost item.
5530 Look for range tests like "ch >= '0' && ch <= '9'".
5531 Look for combinations of simple terms on machines with expensive branches
5532 and evaluate the RHS unconditionally.
5534 For example, if we have p->a == 2 && p->b == 4 and we can make an
5535 object large enough to span both A and B, we can do this with a comparison
5536 against the object ANDed with the a mask.
5538 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5539 operations to do this with one comparison.
5541 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5542 function and the one above.
5544 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5545 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5547 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5548 two operands.
5550 We return the simplified tree or 0 if no optimization is possible. */
5552 static tree
5555 {
5556 /* If this is the "or" of two comparisons, we can do something if
5557 the comparisons are NE_EXPR. If this is the "and", we can do something
5558 if the comparisons are EQ_EXPR. I.e.,
5559 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5561 WANTED_CODE is this operation code. For single bit fields, we can
5562 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5563 comparison for one-bit fields. */
5584 /* Start by getting the comparison codes. Fail if anything is volatile.
5585 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5586 it were surrounded with a NE_EXPR. */
5595 {
5599 }
5602 {
5606 }
5617 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5620 {
5623 {
5628 }
5631 {
5637 }
5638 }
5643 /* If the RHS can be evaluated unconditionally and its operands are
5644 simple, it wins to evaluate the RHS unconditionally on machines
5645 with expensive branches. In this case, this isn't a comparison
5646 that can be merged. */
5653 {
5654 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5665 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5675 }
5677 /* See if the comparisons can be merged. Then get all the parameters for
5678 each side. */
5703 /* It must be true that the inner operation on the lhs of each
5704 comparison must be the same if we are to be able to do anything.
5705 Then see if we have constants. If not, the same must be true for
5706 the rhs's. */
5715 {
5718 }
5723 else
5726 /* If either comparison code is not correct for our logical operation,
5727 fail. However, we can convert a one-bit comparison against zero into
5728 the opposite comparison against that bit being set in the field. */
5732 {
5734 {
5735 /* Make the left operand unsigned, since we are only interested
5736 in the value of one bit. Otherwise we are doing the wrong
5737 thing below. */
5740 }
5741 else
5743 }
5745 /* This is analogous to the code for l_const above. */
5747 {
5749 {
5752 }
5753 else
5755 }
5757 /* See if we can find a mode that contains both fields being compared on
5758 the left. If we can't, fail. Otherwise, update all constants and masks
5759 to be relative to a field of that size. */
5764 volatilep);
5774 {
5777 }
5785 {
5792 {
5796 }
5797 }
5799 {
5806 {
5810 }
5811 }
5813 /* If the right sides are not constant, do the same for it. Also,
5814 disallow this optimization if a size or signedness mismatch occurs
5815 between the left and right sides. */
5817 {
5820 /* Make sure the two fields on the right
5821 correspond to the left without being swapped. */
5829 volatilep);
5839 {
5842 }
5851 /* Make a mask that corresponds to both fields being compared.
5852 Do this for both items being compared. If the operands are the
5853 same size and the bits being compared are in the same position
5854 then we can do this by masking both and comparing the masked
5855 results. */
5859 {
5873 }
5875 /* There is still another way we can do something: If both pairs of
5876 fields being compared are adjacent, we may be able to make a wider
5877 field containing them both.
5879 Note that we still must mask the lhs/rhs expressions. Furthermore,
5880 the mask must be shifted to account for the shift done by
5881 make_bit_field_ref. */
5886 {
5887 tree type;
5903 /* Convert to the smaller type before masking out unwanted bits. */
5906 {
5908 {
5912 }
5914 {
5918 }
5919 }
5928 }
5931 }
5933 /* Handle the case of comparisons with constants. If there is something in
5934 common between the masks, those bits of the constants must be the same.
5935 If not, the condition is always false. Test for this to avoid generating
5936 incorrect code below. */
5941 {
5943 {
5946 }
5947 else
5948 {
5951 }
5952 }
5954 /* Construct the expression we will return. First get the component
5955 reference we will make. Unless the mask is all ones the width of
5956 that field, perform the mask operation. Then compare with the
5957 merged constant. */
5968 }
5969 \f
5970 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5971 constant. */
5973 static tree
5976 {
5979 tree comp_const;
5980 tree minmax_const;
5982 tree inner;
5993 /* If something does not permit us to optimize, return the original tree. */
6001 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6002 and GT_EXPR, doing the rest with recursive calls using logical
6003 simplifications. */
6005 {
6007 {
6008 tree tem
6015 }
6018 return
6020 optimize_minmax_comparison
6022 optimize_minmax_comparison
6027 /* MAX (X, 0) == 0 -> X <= 0 */
6031 /* MAX (X, 0) == 5 -> X == 5 */
6035 /* MAX (X, 0) == -1 -> false */
6039 /* MIN (X, 0) == 0 -> X >= 0 */
6043 /* MIN (X, 0) == 5 -> false */
6046 else
6047 /* MIN (X, 0) == -1 -> X == -1 */
6052 /* MAX (X, 0) > 0 -> X > 0
6053 MAX (X, 0) > 5 -> X > 5 */
6057 /* MAX (X, 0) > -1 -> true */
6061 /* MIN (X, 0) > 0 -> false
6062 MIN (X, 0) > 5 -> false */
6065 else
6066 /* MIN (X, 0) > -1 -> X > -1 */
6071 }
6072 }
6073 \f
6074 /* T is an integer expression that is being multiplied, divided, or taken a
6075 modulus (CODE says which and what kind of divide or modulus) by a
6076 constant C. See if we can eliminate that operation by folding it with
6077 other operations already in T. WIDE_TYPE, if non-null, is a type that
6078 should be used for the computation if wider than our type.
6080 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6081 (X * 2) + (Y * 4). We must, however, be assured that either the original
6082 expression would not overflow or that overflow is undefined for the type
6083 in the language in question.
6085 If we return a non-null expression, it is an equivalent form of the
6086 original computation, but need not be in the original type.
6088 We set *STRICT_OVERFLOW_P to true if the return values depends on
6089 signed overflow being undefined. Otherwise we do not change
6090 *STRICT_OVERFLOW_P. */
6092 static tree
6095 {
6096 /* To avoid exponential search depth, refuse to allow recursion past
6097 three levels. Beyond that (1) it's highly unlikely that we'll find
6098 something interesting and (2) we've probably processed it before
6099 when we built the inner expression. */
6102 tree ret;
6107 depth++;
6109 depth--;
6112 }
6114 static tree
6117 {
6128 /* Don't deal with constants of zero here; they confuse the code below. */
6138 /* Note that we need not handle conditional operations here since fold
6139 already handles those cases. So just do arithmetic here. */
6141 {
6143 /* For a constant, we can always simplify if we are a multiply
6144 or (for divide and modulus) if it is a multiple of our constant. */
6147 {
6150 /* If the multiplication overflowed, we lost information on it.
6151 See PR68142 and PR69845. */
6155 }
6159 /* If op0 is an expression ... */
6165 /* ... and has wrapping overflow, and its type is smaller
6166 than ctype, then we cannot pass through as widening. */
6171 /* ... or this is a truncation (t is narrower than op0),
6172 then we cannot pass through this narrowing. */
6175 /* ... or signedness changes for division or modulus,
6176 then we cannot pass through this conversion. */
6180 /* ... or has undefined overflow while the converted to
6181 type has not, we cannot do the operation in the inner type
6182 as that would introduce undefined overflow. */
6188 /* Pass the constant down and see if we can make a simplification. If
6189 we can, replace this expression with the inner simplification for
6190 possible later conversion to our or some other type. */
6195 code == MULT_EXPR
6197 strict_overflow_p))))
6202 /* If widening the type changes it from signed to unsigned, then we
6203 must avoid building ABS_EXPR itself as unsigned. */
6205 {
6209 {
6212 }
6214 }
6215 /* If the constant is negative, we cannot simplify this. */
6218 /* FALLTHROUGH */
6220 /* For division and modulus, type can't be unsigned, as e.g.
6221 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6222 For signed types, even with wrapping overflow, this is fine. */
6231 /* If widening the type changes the signedness, then we can't perform
6232 this optimization as that changes the result. */
6236 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6242 {
6249 }
6253 /* If the second operand is constant, this is a multiplication
6254 or floor division, by a power of two, so we can treat it that
6255 way unless the multiplier or divisor overflows. Signed
6256 left-shift overflow is implementation-defined rather than
6257 undefined in C90, so do not convert signed left shift into
6258 multiplication. */
6261 /* const_binop may not detect overflow correctly,
6262 so check for it explicitly here. */
6266 size_one_node,
6267 op1)))
6271 ctype,
6273 t1),
6278 /* See if we can eliminate the operation on both sides. If we can, we
6279 can return a new PLUS or MINUS. If we can't, the only remaining
6280 cases where we can do anything are if the second operand is a
6281 constant. */
6287 /* If not multiplication, we can only do this if both operands
6288 are divisible by c. */
6291 {
6296 }
6298 /* If this was a subtraction, negate OP1 and set it to be an addition.
6299 This simplifies the logic below. */
6301 {
6303 /* If OP1 was not easily negatable, the constant may be OP0. */
6305 {
6308 }
6309 }
6314 /* If either OP1 or C are negative, this optimization is not safe for
6315 some of the division and remainder types while for others we need
6316 to change the code. */
6318 {
6326 }
6328 /* If it's a multiply or a division/modulus operation of a multiple
6329 of our constant, do the operation and verify it doesn't overflow. */
6332 {
6335 /* We allow the constant to overflow with wrapping semantics. */
6339 }
6340 else
6343 /* If we have an unsigned type, we cannot widen the operation since it
6344 will change the result if the original computation overflowed. */
6348 /* If we were able to eliminate our operation from the first side,
6349 apply our operation to the second side and reform the PLUS. */
6353 /* The last case is if we are a multiply. In that case, we can
6354 apply the distributive law to commute the multiply and addition
6355 if the multiplication of the constants doesn't overflow
6356 and overflow is defined. With undefined overflow
6357 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6363 op1);
6368 /* We have a special case here if we are doing something like
6369 (C * 8) % 4 since we know that's zero. */
6372 /* If the multiplication can overflow we cannot optimize this. */
6376 {
6379 }
6381 /* ... fall through ... */
6385 /* If we can extract our operation from the LHS, do so and return a
6386 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6387 do something only if the second operand is a constant. */
6401 /* If these are the same operation types, we can associate them
6402 assuming no overflow. */
6404 {
6419 }
6421 /* If these operations "cancel" each other, we have the main
6422 optimizations of this pass, which occur when either constant is a
6423 multiple of the other, in which case we replace this with either an
6424 operation or CODE or TCODE.
6426 If we have an unsigned type, we cannot do this since it will change
6427 the result if the original computation overflowed. */
6434 {
6436 {
6443 }
6445 {
6452 }
6453 }
6458 }
6461 }
6462 \f
6463 /* Return a node which has the indicated constant VALUE (either 0 or
6464 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6465 and is of the indicated TYPE. */
6467 tree
6469 {
6478 else
6480 }
6483 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6484 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6485 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6486 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6487 COND is the first argument to CODE; otherwise (as in the example
6488 given here), it is the second argument. TYPE is the type of the
6489 original expression. Return NULL_TREE if no simplification is
6490 possible. */
6492 static tree
6497 {
6507 {
6511 /* If this operand throws an expression, then it does not make
6512 sense to try to perform a logical or arithmetic operation
6513 involving it. */
6518 }
6521 {
6526 }
6527 else
6528 /* Detect the case of mixing vector and scalar types - bail out. */
6534 /* This transformation is only worthwhile if we don't have to wrap ARG
6535 in a SAVE_EXPR and the operation can be simplified without recursing
6536 on at least one of the branches once its pushed inside the COND_EXPR. */
6545 {
6549 else
6551 }
6553 {
6557 else
6559 }
6561 /* Check that we have simplified at least one of the branches. */
6566 }
6568 \f
6569 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6571 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6572 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6573 ADDEND is the same as X.
6575 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6576 and finite. The problematic cases are when X is zero, and its mode
6577 has signed zeros. In the case of rounding towards -infinity,
6578 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6579 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6581 bool
6583 {
6587 /* Don't allow the fold with -fsignaling-nans. */
6591 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6595 /* In a vector or complex, we would need to check the sign of all zeros. */
6599 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6603 /* The mode has signed zeros, and we have to honor their sign.
6604 In this situation, there is only one case we can return true for.
6605 X - 0 is the same as X unless rounding towards -infinity is
6606 supported. */
6608 }
6610 /* Subroutine of fold() that optimizes comparisons of a division by
6611 a nonzero integer constant against an integer constant, i.e.
6612 X/C1 op C2.
6614 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6615 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6616 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6618 The function returns the constant folded tree if a simplification
6619 can be made, and NULL_TREE otherwise. */
6621 static tree
6624 {
6632 /* We have to do this the hard way to detect unsigned overflow.
6633 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6639 {
6644 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6648 }
6650 {
6654 {
6673 }
6674 }
6675 else
6676 {
6677 /* A negative divisor reverses the relational operators. */
6683 {
6702 }
6703 }
6706 {
6727 {
6730 }
6735 {
6738 }
6743 {
6746 }
6751 {
6754 }
6759 }
6762 }
6765 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6766 equality/inequality test, then return a simplified form of the test
6767 using a sign testing. Otherwise return NULL. TYPE is the desired
6768 result type. */
6770 static tree
6773 tree result_type)
6774 {
6775 /* If this is testing a single bit, we can optimize the test. */
6779 {
6780 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6781 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6785 /* This is only a win if casting to a signed type is cheap,
6786 i.e. when arg00's type is not a partial mode. */
6789 {
6792 result_type,
6795 }
6796 }
6799 }
6801 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6802 equality/inequality test, then return a simplified form of
6803 the test using shifts and logical operations. Otherwise return
6804 NULL. TYPE is the desired result type. */
6806 tree
6809 {
6810 /* If this is testing a single bit, we can optimize the test. */
6814 {
6823 /* First, see if we can fold the single bit test into a sign-bit
6824 test. */
6826 result_type);
6830 /* Otherwise we have (A & C) != 0 where C is a single bit,
6831 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6832 Similarly for (A & C) == 0. */
6834 /* If INNER is a right shift of a constant and it plus BITNUM does
6835 not overflow, adjust BITNUM and INNER. */
6841 {
6844 }
6846 /* If we are going to be able to omit the AND below, we must do our
6847 operations as unsigned. If we must use the AND, we have a choice.
6848 Normally unsigned is faster, but for some machines signed is. */
6866 /* Put the AND last so it can combine with more things. */
6869 /* Make sure to return the proper type. */
6873 }
6875 }
6877 /* Check whether we are allowed to reorder operands arg0 and arg1,
6878 such that the evaluation of arg1 occurs before arg0. */
6880 static bool
6882 {
6889 }
6891 /* Test whether it is preferable two swap two operands, ARG0 and
6892 ARG1, for example because ARG0 is an integer constant and ARG1
6893 isn't. If REORDER is true, only recommend swapping if we can
6894 evaluate the operands in reverse order. */
6896 bool
6898 {
6916 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6917 for commutative and comparison operators. Ensuring a canonical
6918 form allows the optimizers to find additional redundancies without
6919 having to explicitly check for both orderings. */
6925 /* Put SSA_NAMEs last. */
6931 /* Put variables last. */
6938 }
6941 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6942 means A >= Y && A != MAX, but in this case we know that
6943 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6945 static tree
6947 {
6954 else
6963 {
6966 }
6968 {
6971 }
6972 else
6979 {
6980 /* Convert the pointer types into integer before taking the difference. */
6984 }
6985 else
6992 }
6994 /* Fold a sum or difference of at least one multiplication.
6995 Returns the folded tree or NULL if no simplification could be made. */
6997 static tree
7000 {
7004 /* (A * C) +- (B * C) -> (A+-B) * C.
7005 (A * C) +- A -> A * (C+-1).
7006 We are most concerned about the case where C is a constant,
7007 but other combinations show up during loop reduction. Since
7008 it is not difficult, try all four possibilities. */
7011 {
7014 }
7016 {
7019 }
7020 else
7021 {
7022 /* We cannot generate constant 1 for fract. */
7027 }
7029 {
7032 }
7034 {
7036 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7037 the purpose of this canonicalization. */
7041 {
7044 }
7045 else
7047 }
7048 else
7049 {
7050 /* We cannot generate constant 1 for fract. */
7055 }
7067 /* No identical multiplicands; see if we can find a common
7068 power-of-two factor in non-power-of-two multiplies. This
7069 can help in multi-dimensional array access. */
7072 {
7075 tree maybe_same;
7079 /* Move min of absolute values to int11. */
7081 {
7086 }
7087 else
7091 /* The remainder should not be a constant, otherwise we
7092 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7093 increased the number of multiplications necessary. */
7095 {
7103 }
7104 }
7114 }
7116 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7117 specified by EXPR into the buffer PTR of length LEN bytes.
7118 Return the number of bytes placed in the buffer, or zero
7119 upon failure. */
7121 static int
7123 {
7137 {
7139 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7140 number of bytes. */
7144 {
7151 else
7153 }
7154 else
7159 }
7161 }
7164 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7165 specified by EXPR into the buffer PTR of length LEN bytes.
7166 Return the number of bytes placed in the buffer, or zero
7167 upon failure. */
7169 static int
7171 {
7175 FIXED_VALUE_TYPE value;
7191 }
7194 /* Subroutine of native_encode_expr. Encode the REAL_CST
7195 specified by EXPR into the buffer PTR of length LEN bytes.
7196 Return the number of bytes placed in the buffer, or zero
7197 upon failure. */
7199 static int
7201 {
7207 /* There are always 32 bits in each long, no matter the size of
7208 the hosts long. We handle floating point representations with
7209 up to 192 bits. */
7223 {
7228 {
7235 else
7237 }
7238 else
7244 }
7246 }
7248 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7249 specified by EXPR into the buffer PTR of length LEN bytes.
7250 Return the number of bytes placed in the buffer, or zero
7251 upon failure. */
7253 static int
7255 {
7257 tree part;
7272 }
7275 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7276 specified by EXPR into the buffer PTR of length LEN bytes.
7277 Return the number of bytes placed in the buffer, or zero
7278 upon failure. */
7280 static int
7282 {
7292 {
7294 {
7297 }
7308 }
7310 }
7313 /* Subroutine of native_encode_expr. Encode the STRING_CST
7314 specified by EXPR into the buffer PTR of length LEN bytes.
7315 Return the number of bytes placed in the buffer, or zero
7316 upon failure. */
7318 static int
7320 {
7322 HOST_WIDE_INT total_bytes;
7336 {
7339 {
7342 }
7345 }
7346 else
7349 }
7352 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7353 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7354 buffer PTR of length LEN bytes. If OFF is not -1 then start
7355 the encoding at byte offset OFF and encode at most LEN bytes.
7356 Return the number of bytes placed in the buffer, or zero upon failure. */
7358 int
7360 {
7361 /* We don't support starting at negative offset and -1 is special. */
7366 {
7387 }
7388 }
7391 /* Subroutine of native_interpret_expr. Interpret the contents of
7392 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7393 If the buffer cannot be interpreted, return NULL_TREE. */
7395 static tree
7397 {
7407 }
7410 /* Subroutine of native_interpret_expr. Interpret the contents of
7411 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7412 If the buffer cannot be interpreted, return NULL_TREE. */
7414 static tree
7416 {
7418 double_int result;
7419 FIXED_VALUE_TYPE fixed_value;
7429 }
7432 /* Subroutine of native_interpret_expr. Interpret the contents of
7433 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7434 If the buffer cannot be interpreted, return NULL_TREE. */
7436 static tree
7438 {
7442 /* There are always 32 bits in each long, no matter the size of
7443 the hosts long. We handle floating point representations with
7444 up to 192 bits. */
7445 REAL_VALUE_TYPE r;
7456 {
7457 /* Both OFFSET and BYTE index within a long;
7458 bitpos indexes the whole float. */
7461 {
7468 else
7470 }
7471 else
7472 {
7475 {
7476 /* Reverse bytes within each long, or within the entire float
7477 if it's smaller than a long (for HFmode). */
7480 }
7481 }
7485 }
7489 }
7492 /* Subroutine of native_interpret_expr. Interpret the contents of
7493 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7494 If the buffer cannot be interpreted, return NULL_TREE. */
7496 static tree
7498 {
7513 }
7516 /* Subroutine of native_interpret_expr. Interpret the contents of
7517 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7518 If the buffer cannot be interpreted, return NULL_TREE. */
7520 static tree
7522 {
7535 {
7540 }
7542 }
7545 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7546 the buffer PTR of length LEN as a constant of type TYPE. For
7547 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7548 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7549 return NULL_TREE. */
7551 tree
7553 {
7555 {
7577 }
7578 }
7580 /* Returns true if we can interpret the contents of a native encoding
7581 as TYPE. */
7583 static bool
7585 {
7587 {
7600 }
7601 }
7603 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7604 TYPE at compile-time. If we're unable to perform the conversion
7605 return NULL_TREE. */
7607 static tree
7609 {
7610 /* We support up to 512-bit values (for V8DFmode). */
7614 /* Check that the host and target are sane. */
7623 }
7625 /* Build an expression for the address of T. Folds away INDIRECT_REF
7626 to avoid confusing the gimplify process. */
7628 tree
7630 {
7631 /* The size of the object is not relevant when talking about its address. */
7636 {
7641 }
7651 {
7656 }
7657 else
7661 }
7663 /* Build an expression for the address of T. */
7665 tree
7667 {
7671 }
7673 /* Fold a unary expression of code CODE and type TYPE with operand
7674 OP0. Return the folded expression if folding is successful.
7675 Otherwise, return NULL_TREE. */
7677 tree
7679 {
7680 tree tem;
7681 tree arg0;
7689 {
7692 {
7693 /* Don't use STRIP_NOPS, because signedness of argument type
7694 matters. */
7696 }
7697 else
7698 {
7699 /* Strip any conversions that don't change the mode. This
7700 is safe for every expression, except for a comparison
7701 expression because its signedness is derived from its
7702 operands.
7704 Note that this is done as an internal manipulation within
7705 the constant folder, in order to find the simplest
7706 representation of the arguments so that their form can be
7707 studied. In any cases, the appropriate type conversions
7708 should be put back in the tree that will get out of the
7709 constant folder. */
7711 }
7714 {
7717 {
7721 }
7722 }
7723 }
7730 {
7737 {
7751 /* If this was a conversion, and all we did was to move into
7752 inside the COND_EXPR, bring it back out. But leave it if
7753 it is a conversion from integer to integer and the
7754 result precision is no wider than a word since such a
7755 conversion is cheap and may be optimized away by combine,
7756 while it couldn't if it were outside the COND_EXPR. Then return
7757 so we don't get into an infinite recursion loop taking the
7758 conversion out and then back in. */
7770 && (INTEGRAL_TYPE_P
7783 }
7784 }
7787 {
7793 CASE_CONVERT:
7797 {
7798 /* If we have (type) (a CMP b) and type is an integral type, return
7799 new expression involving the new type. Canonicalize
7800 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7801 non-integral type.
7802 Do not fold the result as that would not simplify further, also
7803 folding again results in recursions. */
7813 }
7815 /* Handle (T *)&A.B.C for A being of type T and B and C
7816 living at offset zero. This occurs frequently in
7817 C++ upcasting and then accessing the base. */
7821 {
7823 tree offset;
7824 machine_mode mode;
7826 tree base
7830 /* If the reference was to a (constant) zero offset, we can use
7831 the address of the base if it has the same base type
7832 as the result type and the pointer type is unqualified. */
7839 }
7843 /* Detect assigning a bitfield. */
7845 && DECL_BIT_FIELD
7847 {
7848 /* Don't leave an assignment inside a conversion
7849 unless assigning a bitfield. */
7851 /* First do the assignment, then return converted constant. */
7856 }
7858 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7859 constants (if x has signed type, the sign bit cannot be set
7860 in c). This folds extension into the BIT_AND_EXPR.
7861 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7862 very likely don't have maximal range for their precision and this
7863 transformation effectively doesn't preserve non-maximal ranges. */
7867 {
7878 <= HOST_BITS_PER_WIDE_INT
7880 {
7884 cst &= HOST_WIDE_INT_M1U
7888 && !flag_syntax_only
7891 {
7895 }
7896 }
7898 {
7903 }
7904 }
7906 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7907 cast (T1)X will fold away. We assume that this happens when X itself
7908 is a cast. */
7912 {
7916 return fold_build_pointer_plus_loc
7918 }
7920 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7921 of the same precision, and X is an integer type not narrower than
7922 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7928 {
7934 }
7936 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7937 type of X and Y (integer types only). */
7942 {
7943 /* Be careful not to introduce new overflows. */
7944 tree mult_type;
7947 else
7951 {
7958 }
7959 }
7965 {
7970 }
7981 /* Convert fabs((double)float) into (double)fabsf(float). */
7984 {
7990 targ0));
7991 }
7995 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8014 /* Note that the operand of this must be an int
8015 and its values must be 0 or 1.
8016 ("true" is a fixed value perhaps depending on the language,
8017 but we don't handle values other than 1 correctly yet.) */
8024 /* Fold *&X to X if X is an lvalue. */
8026 {
8033 }
8039 }
8042 /* If the operation was a conversion do _not_ mark a resulting constant
8043 with TREE_OVERFLOW if the original constant was not. These conversions
8044 have implementation defined behavior and retaining the TREE_OVERFLOW
8045 flag here would confuse later passes such as VRP. */
8046 tree
8049 {
8058 }
8060 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8061 operands OP0 and OP1. LOC is the location of the resulting expression.
8062 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8063 Return the folded expression if folding is successful. Otherwise,
8064 return NULL_TREE. */
8065 static tree
8068 {
8069 tree tem;
8071 /* We only do these simplifications if we are optimizing. */
8075 /* Check for things like (A || B) && (A || C). We can convert this
8076 to A || (B && C). Note that either operator can be any of the four
8077 truth and/or operations and the transformation will still be
8078 valid. Also note that we only care about order for the
8079 ANDIF and ORIF operators. If B contains side effects, this
8080 might change the truth-value of A. */
8087 {
8107 /* This case if tricky because we must either have commutative
8108 operators or else A10 must not have side-effects. */
8114 a01);
8115 }
8117 /* See if we can build a range comparison. */
8123 {
8127 }
8131 {
8135 }
8137 /* Check for the possibility of merging component references. If our
8138 lhs is another similar operation, try to merge its rhs with our
8139 rhs. Then try to merge our lhs and rhs. */
8153 {
8160 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8161 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8162 We don't want to pack more than two leafs to a non-IF AND/OR
8163 expression.
8164 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8165 equal to IF-CODE, then we don't want to add right-hand operand.
8166 If the inner right-hand side of left-hand operand has
8167 side-effects, or isn't simple, then we can't add to it,
8168 as otherwise we might destroy if-sequence. */
8171 /* Needed for sequence points to handle trappings, and
8172 side-effects. */
8174 {
8176 arg1);
8178 tem);
8179 }
8180 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8181 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8184 /* Needed for sequence points to handle trappings, and
8185 side-effects. */
8187 {
8192 }
8193 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8194 into (A OR B).
8195 For sequence point consistancy, we need to check for trapping,
8196 and side-effects. */
8200 }
8203 }
8205 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8206 by changing CODE to reduce the magnitude of constants involved in
8207 ARG0 of the comparison.
8208 Returns a canonicalized comparison tree if a simplification was
8209 possible, otherwise returns NULL_TREE.
8210 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8211 valid if signed overflow is undefined. */
8213 static tree
8217 {
8222 /* Match A +- CST code arg1. We can change this only if overflow
8223 is undefined. */
8226 /* In principle pointers also have undefined overflow behavior,
8227 but that causes problems elsewhere. */
8234 /* Identify the constant in arg0 and its sign. */
8238 /* Overflowed constants and zero will cause problems. */
8243 /* See if we can reduce the magnitude of the constant in
8244 arg0 by changing the comparison code. */
8245 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8249 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8253 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8257 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8261 else
8265 /* Now build the constant reduced in magnitude. But not if that
8266 would produce one outside of its types range. */
8282 }
8284 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8285 overflow further. Try to decrease the magnitude of constants involved
8286 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8287 and put sole constants at the second argument position.
8288 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8290 static tree
8293 {
8294 tree t;
8299 /* Try canonicalization by simplifying arg0. */
8304 {
8308 }
8310 /* Try canonicalization by simplifying arg1 using the swapped
8311 comparison. */
8319 }
8321 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8322 space. This is used to avoid issuing overflow warnings for
8323 expressions like &p->x which can not wrap. */
8325 static bool
8327 {
8334 wide_int wi_offset;
8340 else
8356 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8357 array. */
8359 {
8360 HOST_WIDE_INT base_size;
8365 }
8368 }
8370 /* Return a positive integer when the symbol DECL is known to have
8371 a nonzero address, zero when it's known not to (e.g., it's a weak
8372 symbol), and a negative integer when the symbol is not yet in the
8373 symbol table and so whether or not its address is zero is unknown. */
8374 static int
8376 {
8382 }
8384 /* Subroutine of fold_binary. This routine performs all of the
8385 transformations that are common to the equality/inequality
8386 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8387 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8388 fold_binary should call fold_binary. Fold a comparison with
8389 tree code CODE and type TYPE with operands OP0 and OP1. Return
8390 the folded comparison or NULL_TREE. */
8392 static tree
8395 {
8405 /* For comparisons of pointers we can decompose it to a compile time
8406 comparison of the base objects and the offsets into the object.
8407 This requires at least one operand being an ADDR_EXPR or a
8408 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8414 {
8417 machine_mode mode;
8421 /* Get base and offset for the access. Strip ADDR_EXPR for
8422 get_inner_reference, but put it back by stripping INDIRECT_REF
8423 off the base object if possible. indirect_baseN will be true
8424 if baseN is not an address but refers to the object itself. */
8427 {
8428 base0
8434 else
8436 }
8438 {
8442 {
8443 base0
8450 else
8452 }
8455 else
8459 {
8465 {
8468 }
8469 }
8470 }
8474 {
8475 base1
8481 else
8483 }
8485 {
8489 {
8490 base1
8497 else
8499 }
8502 else
8506 {
8512 {
8515 }
8516 }
8517 }
8519 /* If we have equivalent bases we might be able to simplify. */
8523 {
8524 /* We can fold this expression to a constant if the non-constant
8525 offset parts are equal. */
8534 {
8540 "occur when comparing P +- C1 with "
8542 WARN_STRICT_OVERFLOW_CONDITIONAL);
8545 {
8559 }
8560 }
8561 /* We can simplify the comparison to a comparison of the variable
8562 offset parts if the constant offset parts are equal.
8563 Be careful to use signed sizetype here because otherwise we
8564 mess with array offsets in the wrong way. This is possible
8565 because pointer arithmetic is restricted to retain within an
8566 object and overflow on pointer differences is undefined as of
8567 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8569 && (equality_code
8572 {
8573 /* By converting to signed sizetype we cover middle-end pointer
8574 arithmetic which operates on unsigned pointer types of size
8575 type size and ARRAY_REF offsets which are properly sign or
8576 zero extended from their type in case it is narrower than
8577 sizetype. */
8580 else
8584 else
8591 "occur when comparing P +- C1 with "
8593 WARN_STRICT_OVERFLOW_COMPARISON);
8596 }
8597 }
8598 /* For equal offsets we can simplify to a comparison of the
8599 base addresses. */
8601 && (indirect_base0
8603 && (indirect_base1
8608 {
8614 }
8615 /* Comparison between an ordinary (non-weak) symbol and a null
8616 pointer can be eliminated since such symbols must have a non
8617 null address. In C, relational expressions between pointers
8618 to objects and null pointers are undefined. The results
8619 below follow the C++ rules with the additional property that
8620 every object pointer compares greater than a null pointer.
8621 */
8624 /* Avoid folding references to struct members at offset 0 to
8625 prevent tests like '&ptr->firstmember == 0' from getting
8626 eliminated. When ptr is null, although the -> expression
8627 is strictly speaking invalid, GCC retains it as a matter
8628 of QoI. See PR c/44555. */
8630 /* The caller guarantees that when one of the arguments is
8631 constant (i.e., null in this case) it is second. */
8633 {
8635 {
8646 }
8647 }
8648 }
8650 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8651 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8652 the resulting offset is smaller in absolute value than the
8653 original one and has the same sign. */
8662 {
8667 tree cst;
8669 "occur when combining constants around "
8672 /* Put the constant on the side where it doesn't overflow and is
8673 of lower absolute value and of same sign than before. */
8680 {
8683 variable1,
8687 }
8695 {
8701 variable2);
8702 }
8703 }
8709 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8710 constant, we can simplify it. */
8715 {
8719 }
8721 /* If we are comparing an expression that just has comparisons
8722 of two integer values, arithmetic expressions of those comparisons,
8723 and constants, we can simplify it. There are only three cases
8724 to check: the two values can either be equal, the first can be
8725 greater, or the second can be greater. Fold the expression for
8726 those three values. Since each value must be 0 or 1, we have
8727 eight possibilities, each of which corresponds to the constant 0
8728 or 1 or one of the six possible comparisons.
8730 This handles common cases like (a > b) == 0 but also handles
8731 expressions like ((x > y) - (y > x)) > 0, which supposedly
8732 occur in macroized code. */
8735 {
8740 /* Don't handle degenerate cases here; they should already
8741 have been handled anyway. */
8750 {
8754 /* We can't just pass T to eval_subst in case cval1 or cval2
8755 was the same as ARG1. */
8757 tree high_result
8761 arg1);
8762 tree equal_result
8766 arg1);
8767 tree low_result
8771 arg1);
8773 /* All three of these results should be 0 or 1. Confirm they are.
8774 Then use those values to select the proper code to use. */
8779 {
8780 /* Make a 3-bit mask with the high-order bit being the
8781 value for `>', the next for '=', and the low for '<'. */
8785 {
8787 /* Always false. */
8808 /* Always true. */
8810 }
8813 {
8817 }
8819 }
8820 }
8821 }
8823 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8824 into a single range test. */
8832 {
8836 }
8839 }
8842 /* Subroutine of fold_binary. Optimize complex multiplications of the
8843 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8844 argument EXPR represents the expression "z" of type TYPE. */
8846 static tree
8848 {
8853 {
8856 }
8858 {
8861 }
8862 else
8863 {
8867 }
8876 }
8879 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8880 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8882 static bool
8884 {
8888 {
8891 }
8893 {
8899 else
8901 }
8902 else
8908 }
8910 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8911 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8912 NULL_TREE otherwise. */
8914 static tree
8916 {
8933 {
8937 }
8940 {
8946 }
8947 else
8949 }
8951 /* Try to fold a pointer difference of type TYPE two address expressions of
8952 array references AREF0 and AREF1 using location LOC. Return a
8953 simplified expression for the difference or NULL_TREE. */
8955 static tree
8958 {
8963 /* If the bases are array references as well, recurse. If the bases
8964 are pointer indirections compute the difference of the pointers.
8965 If the bases are equal, we are set. */
8968 && (base_offset
8972 && (base_offset
8978 {
8984 base_offset,
8987 }
8989 }
8991 /* If the real or vector real constant CST of type TYPE has an exact
8992 inverse, return it, else return NULL. */
8994 tree
8996 {
8997 REAL_VALUE_TYPE r;
8999 machine_mode mode;
9003 {
9019 {
9024 }
9030 }
9031 }
9033 /* Mask out the tz least significant bits of X of type TYPE where
9034 tz is the number of trailing zeroes in Y. */
9035 static wide_int
9037 {
9042 }
9044 /* Return true when T is an address and is known to be nonzero.
9045 For floating point we further ensure that T is not denormal.
9046 Similar logic is present in nonzero_address in rtlanal.h.
9048 If the return value is based on the assumption that signed overflow
9049 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9050 change *STRICT_OVERFLOW_P. */
9052 static bool
9054 {
9058 /* Doing something useful for floating point would need more work. */
9064 {
9067 strict_overflow_p);
9073 strict_overflow_p);
9081 }
9084 {
9087 strict_overflow_p);
9095 strict_overflow_p);
9110 strict_overflow_p);
9114 strict_overflow_p);
9117 {
9129 }
9133 }
9135 }
9137 /* Return true when T is an address and is known to be nonzero.
9138 Handle warnings about undefined signed overflow. */
9140 static bool
9142 {
9149 "determining that expression is always "
9151 WARN_STRICT_OVERFLOW_MISC);
9153 }
9155 /* Return true if T is known not to be equal to an integer W. */
9157 bool
9159 {
9161 value_range_type rtype;
9163 {
9172 {
9177 }
9182 /* If T has some known zero bits and W has any of those bits set,
9183 then T is known not to be equal to W. */
9191 }
9192 }
9194 /* Fold a binary expression of code CODE and type TYPE with operands
9195 OP0 and OP1. LOC is the location of the resulting expression.
9196 Return the folded expression if folding is successful. Otherwise,
9197 return NULL_TREE. */
9199 tree
9202 {
9217 /* Strip any conversions that don't change the mode. This is
9218 safe for every expression, except for a comparison expression
9219 because its signedness is derived from its operands. So, in
9220 the latter case, only strip conversions that don't change the
9221 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9222 preserved.
9224 Note that this is done as an internal manipulation within the
9225 constant folder, in order to find the simplest representation
9226 of the arguments so that their form can be studied. In any
9227 cases, the appropriate type conversions should be put back in
9228 the tree that will get out of the constant folder. */
9231 {
9234 }
9235 else
9236 {
9239 }
9241 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9242 constant but we can't do arithmetic on them. */
9244 {
9247 {
9251 }
9252 }
9254 /* If this is a commutative operation, and ARG0 is a constant, move it
9255 to ARG1 to reduce the number of tests below. */
9260 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9261 to ARG1 to reduce the number of tests below. */
9270 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9272 First check for cases where an arithmetic operation is applied to a
9273 compound, conditional, or comparison operation. Push the arithmetic
9274 operation inside the compound or conditional to see if any folding
9275 can then be done. Convert comparison to conditional for this purpose.
9276 The also optimizes non-constant cases that used to be done in
9277 expand_expr.
9279 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9280 one of the operands is a comparison and the other is a comparison, a
9281 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9282 code below would make the expression more complex. Change it to a
9283 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9284 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9297 {
9301 boolean_type_node,
9309 }
9313 {
9315 {
9320 tem);
9321 }
9324 {
9329 tem);
9330 }
9335 {
9341 }
9346 {
9352 }
9353 }
9356 {
9358 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9361 {
9367 }
9369 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9372 {
9373 tree base;
9374 HOST_WIDE_INT coffset;
9383 }
9388 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9394 arg1),
9396 arg0)));
9402 {
9403 /* X + (X / CST) * -CST is X % CST. */
9408 {
9417 cst0));
9418 }
9419 }
9421 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9422 one. Make sure the type is not saturating and has the signedness of
9423 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9424 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9431 {
9435 }
9438 {
9439 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9440 (plus (plus (mult) (mult)) (foo)) so that we can
9441 take advantage of the factoring cases below. */
9450 {
9456 else
9469 parg0),
9471 marg)),
9475 return
9481 parg1)));
9482 }
9483 }
9484 else
9485 {
9486 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9487 to __complex__ ( x, y ). This is not the same for SNaNs or
9488 if signed zeros are involved. */
9492 {
9499 {
9503 {
9509 }
9511 {
9517 }
9518 }
9519 }
9527 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9528 We associate floats only if the user has specified
9529 -fassociative-math. */
9533 {
9538 {
9539 tree tree0;
9542 }
9543 }
9544 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9545 We associate floats only if the user has specified
9546 -fassociative-math. */
9550 {
9555 {
9556 tree tree0;
9559 }
9560 }
9561 }
9563 bit_rotate:
9564 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9565 is a rotate of A by C1 bits. */
9566 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9567 is a rotate of A by B bits. */
9568 {
9570 tree rtype;
9579 /* Only create rotates in complete modes. Other cases are not
9580 expanded properly. */
9583 {
9597 {
9601 code0 == LSHIFT_EXPR
9605 }
9607 {
9615 element_precision
9619 return
9622 ? LROTATE_EXPR
9627 }
9629 {
9637 element_precision
9641 return fold_convert_loc
9644 ? LROTATE_EXPR
9648 }
9649 }
9650 }
9652 associate:
9653 /* In most languages, can't associate operations on floats through
9654 parentheses. Rather than remember where the parentheses were, we
9655 don't associate floats at all, unless the user has specified
9656 -fassociative-math.
9657 And, we need to make sure type is not saturating. */
9661 {
9667 /* Split both trees into variables, constants, and literals. Then
9668 associate each group together, the constants with literals,
9669 then the result with variables. This increases the chances of
9670 literals being recombined later and of generating relocatable
9671 expressions for the sum of a constant and literal. */
9677 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9681 /* With undefined overflow prefer doing association in a type
9682 which wraps on overflow, if that is one of the operand types. */
9685 {
9693 }
9695 /* With undefined overflow we can only associate constants with one
9696 variable, and constants whose association doesn't overflow. */
9699 {
9701 {
9707 {
9710 }
9717 {
9720 }
9726 /* The only case we can still associate with two variables
9727 is if they cancel out. */
9731 }
9732 }
9734 /* Only do something if we found more than two objects. Otherwise,
9735 nothing has changed and we risk infinite recursion. */
9741 {
9753 /* Preserve the MINUS_EXPR if the negative part of the literal is
9754 greater than the positive part. Otherwise, the multiplicative
9755 folding code (i.e extract_muldiv) may be fooled in case
9756 unsigned constants are subtracted, like in the following
9757 example: ((X*2 + 4) - 8U)/2. */
9759 {
9763 {
9767 }
9768 else
9769 {
9773 }
9774 }
9776 /* Don't introduce overflows through reassociation. */
9783 {
9785 return
9789 else
9790 {
9793 return
9797 }
9798 }
9801 return
9804 }
9805 }
9810 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9819 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9820 __complex__ ( x, -y ). This is not the same for SNaNs or if
9821 signed zeros are involved. */
9825 {
9832 {
9836 {
9838 arg1r ? arg1r
9843 }
9845 {
9849 arg1i ? arg1i
9852 }
9853 }
9854 }
9856 /* A - B -> A + (-B) if B is easily negatable. */
9860 /* Avoid this transformation if B is a positive REAL_CST. */
9868 /* Fold &a[i] - &a[j] to i-j. */
9873 {
9879 }
9882 && flag_unsafe_math_optimizations
9888 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9889 one. Make sure the type is not saturating and has the signedness of
9890 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9891 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9898 {
9902 }
9908 {
9909 /* Transform x * -C into -x * C if x is easily negatable. */
9923 {
9926 "occur when simplifying "
9928 WARN_STRICT_OVERFLOW_MISC);
9930 }
9932 /* Optimize z * conj(z) for integer complex numbers. */
9939 }
9940 else
9941 {
9942 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9943 This is not the same for NaNs or if signed zeros are
9944 involved. */
9950 {
9953 return
9959 return
9964 }
9966 /* Optimize z * conj(z) for floating point complex numbers.
9967 Guarded by flag_unsafe_math_optimizations as non-finite
9968 imaginary components don't produce scalar results. */
9977 }
9981 /* Canonicalize (X & C1) | C2. */
9985 {
9990 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9998 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10003 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10004 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10005 mode which allows further optimizations. */
10010 {
10014 {
10017 }
10018 }
10025 c3)),
10026 arg1);
10027 }
10029 /* See if this can be simplified into a rotate first. If that
10030 is unsuccessful continue in the association code. */
10034 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10042 /* See if this can be simplified into a rotate first. If that
10043 is unsuccessful continue in the association code. */
10047 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10052 {
10053 tree tem2;
10060 }
10061 /* Fold ~X & 1 as (X & 1) == 0. */
10065 {
10066 tree tem2;
10073 }
10074 /* Fold !X & 1 as X == 0. */
10077 {
10081 }
10083 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10084 multiple of 1 << CST. */
10086 {
10093 }
10095 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10096 bits from CST2. */
10100 {
10108 {
10109 /* Avoid the transform if arg1 is a mask of some
10110 mode which allows further optimizations. */
10117 }
10118 }
10120 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10121 ((A & N) + B) & M -> (A + B) & M
10122 Similarly if (N & M) == 0,
10123 ((A | N) + B) & M -> (A + B) & M
10124 and for - instead of + (or unary - instead of +)
10125 and/or ^ instead of |.
10126 If B is constant and (B & M) == 0, fold into A & M. */
10128 {
10137 {
10140 wide_int cst0;
10142 /* Now we know that arg0 is (C + D) or (C - D) or
10143 -C and arg1 (M) is == (1LL << cst) - 1.
10144 Store C into PMOP[0] and D into PMOP[1]. */
10148 {
10151 }
10158 {
10168 {
10171 }
10174 /* If C or D is of the form (A & N) where
10175 (N & M) == M, or of the form (A | N) or
10176 (A ^ N) where (N & M) == 0, replace it with A. */
10180 /* If C or D is a N where (N & M) == 0, it can be
10181 omitted (assumed 0). */
10189 }
10191 /* Only build anything new if we optimized one or both arguments
10192 above. */
10196 {
10199 {
10200 /* Perform the operations in a type that has defined
10201 overflow behavior. */
10207 }
10212 {
10220 else
10222 }
10225 else
10228 /* TEM is now the new binary +, - or unary - replacement. */
10232 }
10233 }
10234 }
10236 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10239 {
10244 return
10246 }
10251 /* Don't touch a floating-point divide by zero unless the mode
10252 of the constant can represent infinity. */
10258 /* (-A) / (-B) -> A / B */
10270 /* Fall through */
10273 /* Simplify A / (B << N) where A and B are positive and B is
10274 a power of 2, to A >> (N + log2(B)). */
10279 {
10282 {
10290 WARN_STRICT_OVERFLOW_MISC);
10296 }
10297 }
10299 /* Fall through */
10307 /* Convert -A / -B to A / B when the type is signed and overflow is
10308 undefined. */
10312 {
10315 "when distributing negation across "
10317 WARN_STRICT_OVERFLOW_MISC);
10322 }
10326 {
10329 "when distributing negation across "
10331 WARN_STRICT_OVERFLOW_MISC);
10336 }
10338 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10339 operation, EXACT_DIV_EXPR.
10341 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10342 At one time others generated faster code, it's not clear if they do
10343 after the last round to changes to the DIV code in expmed.c. */
10354 {
10358 WARN_STRICT_OVERFLOW_MISC);
10360 }
10372 {
10376 WARN_STRICT_OVERFLOW_MISC);
10378 }
10386 /* Since negative shift count is not well-defined,
10387 don't try to compute it in the compiler. */
10393 /* If we have a rotate of a bit operation with the rotate count and
10394 the second operand of the bit operation both constant,
10395 permute the two operations. */
10407 /* Two consecutive rotates adding up to the some integer
10408 multiple of the precision of the type can be ignored. */
10423 /* Note that the operands of this must be ints
10424 and their values must be 0 or 1.
10425 ("true" is a fixed value perhaps depending on the language.) */
10426 /* If first arg is constant zero, return it. */
10430 /* If either arg is constant true, drop it. */
10434 /* Preserve sequence points. */
10437 /* If second arg is constant zero, result is zero, but first arg
10438 must be evaluated. */
10441 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10442 case will be handled here. */
10446 /* !X && X is always false. */
10450 /* X && !X is always false. */
10455 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10456 means A >= Y && A != MAX, but in this case we know that
10457 A < X <= MAX. */
10461 {
10469 }
10478 /* Note that the operands of this must be ints
10479 and their values must be 0 or true.
10480 ("true" is a fixed value perhaps depending on the language.) */
10481 /* If first arg is constant true, return it. */
10485 /* If either arg is constant zero, drop it. */
10489 /* Preserve sequence points. */
10492 /* If second arg is constant true, result is true, but we must
10493 evaluate first arg. */
10496 /* Likewise for first arg, but note this only occurs here for
10497 TRUTH_OR_EXPR. */
10501 /* !X || X is always true. */
10505 /* X || !X is always true. */
10510 /* (X && !Y) || (!X && Y) is X ^ Y */
10513 {
10530 }
10539 /* If the second arg is constant zero, drop it. */
10542 /* If the second arg is constant true, this is a logical inversion. */
10544 {
10547 }
10548 /* Identical arguments cancel to zero. */
10552 /* !X ^ X is always true. */
10557 /* X ^ !X is always true. */
10573 /* bool_var != 1 becomes !bool_var. */
10580 /* bool_var == 0 becomes !bool_var. */
10587 /* !exp != 0 becomes !exp */
10592 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10601 {
10607 }
10609 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10618 {
10624 }
10626 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10634 code == NE_EXPR
10638 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10646 code == NE_EXPR
10650 /* If this is an EQ or NE comparison with zero and ARG0 is
10651 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10652 two operations, but the latter can be done in one less insn
10653 on machines that have only two-operand insns or on which a
10654 constant cannot be the first operand. */
10657 {
10662 {
10669 arg1);
10670 }
10673 {
10680 arg1);
10681 }
10682 }
10684 /* If this is an NE or EQ comparison of zero against the result of a
10685 signed MOD operation whose second operand is a power of 2, make
10686 the MOD operation unsigned since it is simpler and equivalent. */
10694 {
10704 }
10706 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10707 C1 is a valid shift constant, and C2 is a power of two, i.e.
10708 a single bit. */
10712 == INTEGER_CST
10715 {
10720 /* Check for a valid shift count. */
10722 {
10726 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10727 can be rewritten as (X & (C2 << C1)) != 0. */
10729 {
10734 }
10735 /* Otherwise, for signed (arithmetic) shifts,
10736 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10737 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10741 /* Otherwise, of unsigned (logical) shifts,
10742 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10743 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10744 else
10748 arg000);
10749 }
10750 }
10752 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10753 Similarly for NE_EXPR. */
10757 {
10761 tree dandnotc
10764 notc);
10768 }
10770 /* If this is a comparison of a field, we may be able to simplify it. */
10773 /* Handle the constant case even without -O
10774 to make sure the warnings are given. */
10776 {
10780 }
10782 /* Optimize comparisons of strlen vs zero to a compare of the
10783 first character of the string vs zero. To wit,
10784 strlen(ptr) == 0 => *ptr == 0
10785 strlen(ptr) != 0 => *ptr != 0
10786 Other cases should reduce to one of these two (or a constant)
10787 due to the return value of strlen being unsigned. */
10790 {
10798 {
10803 }
10804 }
10806 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10807 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10811 {
10816 {
10818 {
10821 }
10824 }
10825 }
10827 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10828 (X & C) == 0 when C is a single bit. */
10833 {
10840 arg1));
10841 }
10843 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10844 constant C is a power of two, i.e. a single bit. */
10851 {
10855 }
10857 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10858 when is C is a power of two, i.e. a single bit. */
10865 {
10871 }
10875 {
10878 }
10880 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10883 {
10896 arg01),
10905 arg01),
10914 arg00),
10923 arg00),
10925 }
10929 {
10936 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10937 operand_equal_p guarantees no side-effects so we don't need
10938 to use omit_one_operand on Z. */
10942 arg10));
10946 arg11));
10950 arg10));
10954 arg11));
10956 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10959 {
10965 }
10966 }
10968 /* Attempt to simplify equality/inequality comparisons of complex
10969 values. Only lower the comparison if the result is known or
10970 can be simplified to a single scalar comparison. */
10975 {
10980 {
10983 }
10984 else
10985 {
10988 }
10991 {
10994 }
10995 else
10996 {
10999 }
11003 {
11005 {
11010 }
11011 else
11012 {
11017 }
11018 }
11022 {
11024 {
11029 }
11030 else
11031 {
11036 }
11037 }
11038 }
11050 /* Transform comparisons of the form X +- C CMP X. */
11057 {
11064 else
11067 /* (X - c) > X becomes false. */
11071 {
11075 "occur when assuming that (X - c) > X "
11077 WARN_STRICT_OVERFLOW_ALL);
11079 }
11081 /* Likewise (X + c) < X becomes false. */
11085 {
11089 "occur when assuming that "
11091 WARN_STRICT_OVERFLOW_ALL);
11093 }
11095 /* Convert (X - c) <= X to true. */
11100 {
11104 "occur when assuming that "
11106 WARN_STRICT_OVERFLOW_ALL);
11108 }
11110 /* Convert (X + c) >= X to true. */
11115 {
11119 "occur when assuming that "
11121 WARN_STRICT_OVERFLOW_ALL);
11123 }
11126 {
11127 /* Convert X + c > X and X - c < X to true for integers. */
11131 {
11134 "not occur when assuming that "
11136 WARN_STRICT_OVERFLOW_ALL);
11138 }
11143 {
11146 "not occur when assuming that "
11148 WARN_STRICT_OVERFLOW_ALL);
11150 }
11152 /* Convert X + c <= X and X - c >= X to false for integers. */
11156 {
11159 "not occur when assuming that "
11161 WARN_STRICT_OVERFLOW_ALL);
11163 }
11168 {
11171 "not occur when assuming that "
11173 WARN_STRICT_OVERFLOW_ALL);
11175 }
11176 }
11177 }
11179 /* If we are comparing an ABS_EXPR with a constant, we can
11180 convert all the cases into explicit comparisons, but they may
11181 well not be faster than doing the ABS and one comparison.
11182 But ABS (X) <= C is a range comparison, which becomes a subtraction
11183 and a comparison, and is probably faster. */
11197 /* Convert ABS_EXPR<x> >= 0 to true. */
11204 {
11207 "when simplifying comparison of "
11209 WARN_STRICT_OVERFLOW_CONDITIONAL);
11212 arg0);
11213 }
11215 /* Convert ABS_EXPR<x> < 0 to false. */
11220 {
11223 "when simplifying comparison of "
11225 WARN_STRICT_OVERFLOW_CONDITIONAL);
11228 arg0);
11229 }
11231 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11232 and similarly for >= into !=. */
11242 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11243 otherwise Y might be >= # of bits in X's type and thus e.g.
11244 (unsigned char) (1 << Y) for Y 15 might be 0.
11245 If the cast is widening, then 1 << Y should have unsigned type,
11246 otherwise if Y is number of bits in the signed shift type minus 1,
11247 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11248 31 might be 0xffffffff80000000. */
11259 {
11265 }
11277 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11278 {
11290 }
11295 /* When pedantic, a compound expression can be neither an lvalue
11296 nor an integer constant expression. */
11299 /* Don't let (0, 0) be null pointer constant. */
11305 /* An ASSERT_EXPR should never be passed to fold_binary. */
11311 }
11313 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11314 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11315 of GOTO_EXPR. */
11317 static tree
11319 {
11321 {
11328 /* ... fall through ... */
11332 }
11333 }
11335 /* Return whether the sub-tree ST contains a label which is accessible from
11336 outside the sub-tree. */
11338 static bool
11340 {
11341 return
11343 }
11345 /* Fold a ternary expression of code CODE and type TYPE with operands
11346 OP0, OP1, and OP2. Return the folded expression if folding is
11347 successful. Otherwise, return NULL_TREE. */
11349 tree
11352 {
11353 tree tem;
11360 /* If this is a commutative operation, and OP0 is a constant, move it
11361 to OP1 to reduce the number of tests below. */
11370 /* Strip any conversions that don't change the mode. This is safe
11371 for every expression, except for a comparison expression because
11372 its signedness is derived from its operands. So, in the latter
11373 case, only strip conversions that don't change the signedness.
11375 Note that this is done as an internal manipulation within the
11376 constant folder, in order to find the simplest representation of
11377 the arguments so that their form can be studied. In any cases,
11378 the appropriate type conversions should be put back in the tree
11379 that will get out of the constant folder. */
11381 {
11384 }
11387 {
11390 }
11393 {
11396 }
11399 {
11403 {
11409 }
11414 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11415 so all simple results must be passed through pedantic_non_lvalue. */
11417 {
11420 /* Only optimize constant conditions when the selected branch
11421 has the same type as the COND_EXPR. This avoids optimizing
11422 away "c ? x : throw", where the throw has a void type.
11423 Avoid throwing away that operand which contains label. */
11430 }
11432 {
11437 {
11442 {
11450 }
11454 }
11455 }
11457 /* If we have A op B ? A : C, we may be able to convert this to a
11458 simpler expression, depending on the operation and the values
11459 of B and C. Signed zeros prevent all of these transformations,
11460 for reasons given above each one.
11462 Also try swapping the arguments and inverting the conditional. */
11467 {
11471 }
11475 op2,
11478 {
11482 {
11486 }
11487 }
11489 /* If the second operand is simpler than the third, swap them
11490 since that produces better jump optimization results. */
11493 {
11495 /* See if this can be inverted. If it can't, possibly because
11496 it was a floating-point inequality comparison, don't do
11497 anything. */
11501 }
11503 /* Convert A ? 1 : 0 to simply A. */
11508 /* If we try to convert OP0 to our type, the
11509 call to fold will try to move the conversion inside
11510 a COND, which will recurse. In that case, the COND_EXPR
11511 is probably the best choice, so leave it alone. */
11515 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11516 over COND_EXPR in cases such as floating point comparisons. */
11525 arg0)));
11527 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11532 {
11533 /* sign_bit_p looks through both zero and sign extensions,
11534 but for this optimization only sign extensions are
11535 usable. */
11538 {
11541 {
11544 }
11546 }
11547 /* sign_bit_p only checks ARG1 bits within A's precision.
11548 If <sign bit of A> has wider type than A, bits outside
11549 of A's precision in <sign bit of A> need to be checked.
11550 If they are all 0, this optimization needs to be done
11551 in unsigned A's type, if they are all 1 in signed A's type,
11552 otherwise this can't be done. */
11558 {
11560 tree tem_type;
11573 {
11576 }
11578 {
11581 }
11582 else
11584 }
11587 return
11593 arg1)));
11594 }
11596 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11597 already handled above. */
11602 {
11611 }
11613 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11614 is probably obsolete because the first operand should be a
11615 truth value (that's why we have the two cases above), but let's
11616 leave it in until we can confirm this for all front-ends. */
11628 /* Disable the transformations below for vectors, since
11629 fold_binary_op_with_conditional_arg may undo them immediately,
11630 yielding an infinite loop. */
11634 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11643 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11648 {
11650 /* Only perform transformation if ARG0 is easily inverted. */
11654 ? BIT_IOR_EXPR
11657 arg1);
11658 }
11660 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11665 {
11667 /* Only perform transformation if ARG0 is easily inverted. */
11673 op2);
11674 }
11676 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11688 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11689 of fold_ternary on them. */
11697 {
11707 {
11712 {
11720 }
11721 }
11722 }
11724 /* On constants we can use native encode/interpret to constant
11725 fold (nearly) all BIT_FIELD_REFs. */
11729 {
11732 /* Limit us to a reasonable amount of work. To relax the
11733 other limitations we need bit-shifting of the buffer
11734 and rounding up the size. */
11738 {
11740 unsigned HOST_WIDE_INT len
11745 {
11750 }
11751 }
11752 }
11757 /* For integers we can decompose the FMA if possible. */
11769 {
11785 {
11790 /* Make sure that the perm value is in an acceptable
11791 range. */
11800 else
11805 }
11808 {
11813 }
11818 {
11823 }
11829 {
11833 }
11838 /* Some targets are deficient and fail to expand a single
11839 argument permutation while still allowing an equivalent
11840 2-argument version. */
11844 {
11847 }
11850 {
11857 }
11861 }
11865 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11868 {
11874 wide_int tem2
11878 }
11883 {
11885 unsigned HOST_WIDE_INT elsize
11888 {
11892 else
11893 {
11899 }
11900 }
11901 }
11907 }
11909 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11910 of an array (or vector). */
11912 tree
11914 {
11919 {
11922 {
11923 /* Static constructors for variably sized objects makes no sense. */
11927 }
11928 }
11939 offset_int max_index;
11944 {
11945 /* Array constructor might explicitly set index, or specify a range,
11946 or leave index NULL meaning that it is next index after previous
11947 one. */
11949 {
11952 else
11953 {
11957 }
11958 }
11959 else
11960 {
11966 }
11968 /* Do we have match? */
11972 }
11974 }
11976 /* Perform constant folding and related simplification of EXPR.
11977 The related simplifications include x*1 => x, x*0 => 0, etc.,
11978 and application of the associative law.
11979 NOP_EXPR conversions may be removed freely (as long as we
11980 are careful not to change the type of the overall expression).
11981 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11982 but we can constant-fold them if they have constant operands. */
11984 #ifdef ENABLE_FOLD_CHECKING
11985 # define fold(x) fold_1 (x)
11987 static
11988 #endif
11989 tree
11991 {
11995 tree tem;
11998 /* Return right away if a constant. */
12002 /* CALL_EXPR-like objects with variable numbers of operands are
12003 treated specially. */
12005 {
12007 {
12010 }
12012 }
12015 {
12020 {
12038 }
12039 }
12042 {
12044 {
12051 {
12056 }
12059 }
12061 /* Return a VECTOR_CST if possible. */
12063 {
12069 tree val;
12075 }
12083 }
12085 #ifdef ENABLE_FOLD_CHECKING
12086 #undef fold
12093 /* When --enable-checking=fold, compute a digest of expr before
12094 and after actual fold call to see if fold did not accidentally
12095 change original expr. */
12097 tree
12099 {
12100 tree ret;
12120 }
12122 void
12124 {
12135 }
12137 static void
12139 {
12141 }
12143 static void
12146 {
12152 recursive_label:
12162 {
12163 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12168 }
12176 {
12177 /* Allow these fields to be modified. */
12178 tree tmp;
12187 {
12190 }
12191 }
12202 {
12205 {
12220 }
12224 {
12237 }
12254 {
12260 }
12263 {
12265 {
12268 }
12270 }
12281 {
12284 }
12294 }
12295 }
12297 /* Helper function for outputting the checksum of a tree T. When
12298 debugging with gdb, you can "define mynext" to be "next" followed
12299 by "call debug_fold_checksum (op0)", then just trace down till the
12300 outputs differ. */
12302 DEBUG_FUNCTION void
12304 {
12319 }
12321 #endif
12323 /* Fold a unary tree expression with code CODE of type TYPE with an
12324 operand OP0. LOC is the location of the resulting expression.
12325 Return a folded expression if successful. Otherwise, return a tree
12326 expression with code CODE of type TYPE with an operand OP0. */
12328 tree
12331 {
12332 tree tem;
12333 #ifdef ENABLE_FOLD_CHECKING
12342 #endif
12348 #ifdef ENABLE_FOLD_CHECKING
12355 #endif
12357 }
12359 /* Fold a binary tree expression with code CODE of type TYPE with
12360 operands OP0 and OP1. LOC is the location of the resulting
12361 expression. Return a folded expression if successful. Otherwise,
12362 return a tree expression with code CODE of type TYPE with operands
12363 OP0 and OP1. */
12365 tree
12368 MEM_STAT_DECL)
12369 {
12370 tree tem;
12371 #ifdef ENABLE_FOLD_CHECKING
12388 #endif
12394 #ifdef ENABLE_FOLD_CHECKING
12409 #endif
12411 }
12413 /* Fold a ternary tree expression with code CODE of type TYPE with
12414 operands OP0, OP1, and OP2. Return a folded expression if
12415 successful. Otherwise, return a tree expression with code CODE of
12416 type TYPE with operands OP0, OP1, and OP2. */
12418 tree
12421 {
12422 tree tem;
12423 #ifdef ENABLE_FOLD_CHECKING
12447 #endif
12454 #ifdef ENABLE_FOLD_CHECKING
12477 #endif
12479 }
12481 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12482 arguments in ARGARRAY, and a null static chain.
12483 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12484 of type TYPE from the given operands as constructed by build_call_array. */
12486 tree
12489 {
12490 tree tem;
12491 #ifdef ENABLE_FOLD_CHECKING
12510 #endif
12516 #ifdef ENABLE_FOLD_CHECKING
12532 #endif
12534 }
12536 /* Perform constant folding and related simplification of initializer
12537 expression EXPR. These behave identically to "fold_buildN" but ignore
12538 potential run-time traps and exceptions that fold must preserve. */
12540 #define START_FOLD_INIT \
12541 int saved_signaling_nans = flag_signaling_nans;\
12542 int saved_trapping_math = flag_trapping_math;\
12543 int saved_rounding_math = flag_rounding_math;\
12544 int saved_trapv = flag_trapv;\
12545 int saved_folding_initializer = folding_initializer;\
12546 flag_signaling_nans = 0;\
12547 flag_trapping_math = 0;\
12548 flag_rounding_math = 0;\
12549 flag_trapv = 0;\
12550 folding_initializer = 1;
12552 #define END_FOLD_INIT \
12553 flag_signaling_nans = saved_signaling_nans;\
12554 flag_trapping_math = saved_trapping_math;\
12555 flag_rounding_math = saved_rounding_math;\
12556 flag_trapv = saved_trapv;\
12557 folding_initializer = saved_folding_initializer;
12559 tree
12562 {
12563 tree result;
12564 START_FOLD_INIT;
12568 END_FOLD_INIT;
12570 }
12572 tree
12575 {
12576 tree result;
12577 START_FOLD_INIT;
12581 END_FOLD_INIT;
12583 }
12585 tree
12588 {
12589 tree result;
12590 START_FOLD_INIT;
12594 END_FOLD_INIT;
12596 }
12598 #undef START_FOLD_INIT
12599 #undef END_FOLD_INIT
12601 /* Determine if first argument is a multiple of second argument. Return 0 if
12602 it is not, or we cannot easily determined it to be.
12604 An example of the sort of thing we care about (at this point; this routine
12605 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12606 fold cases do now) is discovering that
12608 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12610 is a multiple of
12612 SAVE_EXPR (J * 8)
12614 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12616 This code also handles discovering that
12618 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12620 is a multiple of 8 so we don't have to worry about dealing with a
12621 possible remainder.
12623 Note that we *look* inside a SAVE_EXPR only to determine how it was
12624 calculated; it is not safe for fold to do much of anything else with the
12625 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12626 at run time. For example, the latter example above *cannot* be implemented
12627 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12628 evaluation time of the original SAVE_EXPR is not necessarily the same at
12629 the time the new expression is evaluated. The only optimization of this
12630 sort that would be valid is changing
12632 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12634 divided by 8 to
12636 SAVE_EXPR (I) * SAVE_EXPR (J)
12638 (where the same SAVE_EXPR (J) is used in the original and the
12639 transformed version). */
12641 int
12643 {
12651 {
12653 /* Bitwise and provides a power of two multiple. If the mask is
12654 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12657 /* FALLTHRU */
12670 {
12674 /* const_binop may not detect overflow correctly,
12675 so check for it explicitly here. */
12679 size_one_node,
12680 op1)))
12683 }
12687 /* Can't handle conversions from non-integral or wider integral type. */
12693 /* .. fall through ... */
12710 SIGNED);
12714 }
12715 }
12717 #define tree_expr_nonnegative_warnv_p(X, Y) \
12720 #define RECURSE(X) \
12721 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12723 /* Return true if CODE or TYPE is known to be non-negative. */
12725 static bool
12727 {
12730 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12731 have a signed:1 type (where the value is -1 and 0). */
12734 }
12736 /* Return true if (CODE OP0) is known to be non-negative. If the return
12737 value is based on the assumption that signed overflow is undefined,
12738 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12739 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12741 bool
12744 {
12749 {
12751 /* We can't return 1 if flag_wrapv is set because
12752 ABS_EXPR<INT_MIN> = INT_MIN. */
12756 {
12759 }
12767 CASE_CONVERT:
12768 {
12773 {
12777 {
12781 }
12782 }
12784 {
12790 }
12791 }
12796 }
12798 /* We don't know sign of `t', so be conservative and return false. */
12800 }
12802 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12803 value is based on the assumption that signed overflow is undefined,
12804 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12805 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12807 bool
12811 {
12816 {
12822 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12823 both unsigned and at least 2 bits shorter than the result. */
12827 {
12832 {
12836 }
12837 }
12842 {
12843 /* x * x is always non-negative for floating point x
12844 or without overflow. */
12847 {
12852 }
12853 }
12855 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12856 both unsigned and their total bits is shorter than the result. */
12860 {
12879 {
12889 }
12890 }
12917 }
12919 /* We don't know sign of `t', so be conservative and return false. */
12921 }
12923 /* Return true if T is known to be non-negative. If the return
12924 value is based on the assumption that signed overflow is undefined,
12925 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12926 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12928 bool
12930 {
12935 {
12949 /* Limit the depth of recursion to avoid quadratic behavior.
12950 This is expected to catch almost all occurrences in practice.
12951 If this code misses important cases that unbounded recursion
12952 would not, passes that need this information could be revised
12953 to provide it through dataflow propagation. */
12961 }
12962 }
12964 /* Return true if T is known to be non-negative. If the return
12965 value is based on the assumption that signed overflow is undefined,
12966 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12967 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12969 bool
12972 {
12974 {
12975 CASE_CFN_ACOS:
12976 CASE_CFN_ACOSH:
12977 CASE_CFN_CABS:
12978 CASE_CFN_COSH:
12979 CASE_CFN_ERFC:
12980 CASE_CFN_EXP:
12981 CASE_CFN_EXP10:
12982 CASE_CFN_EXP2:
12983 CASE_CFN_FABS:
12984 CASE_CFN_FDIM:
12985 CASE_CFN_HYPOT:
12986 CASE_CFN_POW10:
12987 CASE_CFN_FFS:
12988 CASE_CFN_PARITY:
12989 CASE_CFN_POPCOUNT:
12990 CASE_CFN_CLZ:
12991 CASE_CFN_CLRSB:
12994 /* Always true. */
12997 CASE_CFN_SQRT:
12998 /* sqrt(-0.0) is -0.0. */
13003 CASE_CFN_ASINH:
13004 CASE_CFN_ATAN:
13005 CASE_CFN_ATANH:
13006 CASE_CFN_CBRT:
13007 CASE_CFN_CEIL:
13008 CASE_CFN_ERF:
13009 CASE_CFN_EXPM1:
13010 CASE_CFN_FLOOR:
13011 CASE_CFN_FMOD:
13012 CASE_CFN_FREXP:
13013 CASE_CFN_ICEIL:
13014 CASE_CFN_IFLOOR:
13015 CASE_CFN_IRINT:
13016 CASE_CFN_IROUND:
13017 CASE_CFN_LCEIL:
13018 CASE_CFN_LDEXP:
13019 CASE_CFN_LFLOOR:
13020 CASE_CFN_LLCEIL:
13021 CASE_CFN_LLFLOOR:
13022 CASE_CFN_LLRINT:
13023 CASE_CFN_LLROUND:
13024 CASE_CFN_LRINT:
13025 CASE_CFN_LROUND:
13026 CASE_CFN_MODF:
13027 CASE_CFN_NEARBYINT:
13028 CASE_CFN_RINT:
13029 CASE_CFN_ROUND:
13030 CASE_CFN_SCALB:
13031 CASE_CFN_SCALBLN:
13032 CASE_CFN_SCALBN:
13033 CASE_CFN_SIGNBIT:
13034 CASE_CFN_SIGNIFICAND:
13035 CASE_CFN_SINH:
13036 CASE_CFN_TANH:
13037 CASE_CFN_TRUNC:
13038 /* True if the 1st argument is nonnegative. */
13041 CASE_CFN_FMAX:
13042 /* True if the 1st OR 2nd arguments are nonnegative. */
13045 CASE_CFN_FMIN:
13046 /* True if the 1st AND 2nd arguments are nonnegative. */
13049 CASE_CFN_COPYSIGN:
13050 /* True if the 2nd argument is nonnegative. */
13053 CASE_CFN_POWI:
13054 /* True if the 1st argument is nonnegative or the second
13055 argument is an even integer. */
13061 CASE_CFN_POW:
13062 /* True if the 1st argument is nonnegative or the second
13063 argument is an even integer valued real. */
13065 {
13066 REAL_VALUE_TYPE c;
13067 HOST_WIDE_INT n;
13072 {
13073 REAL_VALUE_TYPE cint;
13077 }
13078 }
13083 }
13085 }
13087 /* Return true if T is known to be non-negative. If the return
13088 value is based on the assumption that signed overflow is undefined,
13089 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13090 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13092 static bool
13094 {
13100 {
13102 {
13106 /* If the initializer is non-void, then it's a normal expression
13107 that will be assigned to the slot. */
13111 /* Otherwise, the initializer sets the slot in some way. One common
13112 way is an assignment statement at the end of the initializer. */
13114 {
13122 else
13124 }
13130 }
13133 {
13139 arg0,
13140 arg1,
13142 }
13155 }
13156 }
13158 #undef RECURSE
13159 #undef tree_expr_nonnegative_warnv_p
13161 /* Return true if T is known to be non-negative. If the return
13162 value is based on the assumption that signed overflow is undefined,
13163 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13164 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13166 bool
13168 {
13175 {
13197 }
13200 {
13226 }
13227 }
13229 /* Return true if `t' is known to be non-negative. Handle warnings
13230 about undefined signed overflow. */
13232 bool
13234 {
13241 "determining that expression is always "
13243 WARN_STRICT_OVERFLOW_MISC);
13245 }
13248 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13249 For floating point we further ensure that T is not denormal.
13250 Similar logic is present in nonzero_address in rtlanal.h.
13252 If the return value is based on the assumption that signed overflow
13253 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13254 change *STRICT_OVERFLOW_P. */
13256 bool
13259 {
13261 {
13264 strict_overflow_p);
13267 {
13273 strict_overflow_p));
13274 }
13279 strict_overflow_p);
13283 }
13286 }
13288 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13289 For floating point we further ensure that T is not denormal.
13290 Similar logic is present in nonzero_address in rtlanal.h.
13292 If the return value is based on the assumption that signed overflow
13293 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13294 change *STRICT_OVERFLOW_P. */
13296 bool
13298 tree type,
13299 tree op0,
13301 {
13304 {
13308 {
13309 /* With the presence of negative values it is hard
13310 to say something. */
13317 /* One of operands must be positive and the other non-negative. */
13318 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13319 overflows, on a twos-complement machine the sum of two
13320 nonnegative numbers can never be zero. */
13322 strict_overflow_p)
13324 strict_overflow_p));
13325 }
13330 {
13332 strict_overflow_p)
13334 strict_overflow_p))
13335 {
13338 }
13339 }
13348 {
13351 }
13358 {
13362 /* When both operands are nonzero, then MAX must be too. */
13364 strict_overflow_p))
13367 /* MAX where operand 0 is positive is positive. */
13369 strict_overflow_p);
13370 }
13371 /* MAX where operand 1 is positive is positive. */
13376 {
13380 }
13385 strict_overflow_p)
13387 strict_overflow_p));
13391 }
13394 }
13396 /* Return true when T is an address and is known to be nonzero.
13397 For floating point we further ensure that T is not denormal.
13398 Similar logic is present in nonzero_address in rtlanal.h.
13400 If the return value is based on the assumption that signed overflow
13401 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13402 change *STRICT_OVERFLOW_P. */
13404 bool
13406 {
13409 {
13414 {
13426 /* For objects in symbol table check if we know they are non-zero.
13427 Don't do anything for variables and functions before symtab is built;
13428 it is quite possible that they will be declared weak later. */
13433 /* Function local objects are never NULL. */
13440 /* Constants are never weak. */
13445 }
13453 {
13457 }
13462 }
13464 }
13466 #define integer_valued_real_p(X) \
13469 #define RECURSE(X) \
13470 ((integer_valued_real_p) (X, depth + 1))
13472 /* Return true if the floating point result of (CODE OP0) has an
13473 integer value. We also allow +Inf, -Inf and NaN to be considered
13474 integer values. Return false for signaling NaN.
13476 DEPTH is the current nesting depth of the query. */
13478 bool
13480 {
13482 {
13489 CASE_CONVERT:
13490 {
13497 }
13501 }
13503 }
13505 /* Return true if the floating point result of (CODE OP0 OP1) has an
13506 integer value. We also allow +Inf, -Inf and NaN to be considered
13507 integer values. Return false for signaling NaN.
13509 DEPTH is the current nesting depth of the query. */
13511 bool
13513 {
13515 {
13525 }
13527 }
13529 /* Return true if the floating point result of calling FNDECL with arguments
13530 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13531 considered integer values. Return false for signaling NaN. If FNDECL
13532 takes fewer than 2 arguments, the remaining ARGn are null.
13534 DEPTH is the current nesting depth of the query. */
13536 bool
13538 {
13540 {
13541 CASE_CFN_CEIL:
13542 CASE_CFN_FLOOR:
13543 CASE_CFN_NEARBYINT:
13544 CASE_CFN_RINT:
13545 CASE_CFN_ROUND:
13546 CASE_CFN_TRUNC:
13549 CASE_CFN_FMIN:
13550 CASE_CFN_FMAX:
13555 }
13557 }
13559 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13560 has an integer value. We also allow +Inf, -Inf and NaN to be
13561 considered integer values. Return false for signaling NaN.
13563 DEPTH is the current nesting depth of the query. */
13565 bool
13567 {
13569 {
13577 /* Limit the depth of recursion to avoid quadratic behavior.
13578 This is expected to catch almost all occurrences in practice.
13579 If this code misses important cases that unbounded recursion
13580 would not, passes that need this information could be revised
13581 to provide it through dataflow propagation. */
13585 depth));
13589 }
13591 }
13593 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13594 has an integer value. We also allow +Inf, -Inf and NaN to be
13595 considered integer values. Return false for signaling NaN.
13597 DEPTH is the current nesting depth of the query. */
13599 static bool
13601 {
13603 {
13614 }
13616 }
13618 #undef RECURSE
13619 #undef integer_valued_real_p
13621 /* Return true if the floating point expression T has an integer value.
13622 We also allow +Inf, -Inf and NaN to be considered integer values.
13623 Return false for signaling NaN.
13625 DEPTH is the current nesting depth of the query. */
13627 bool
13629 {
13635 {
13651 }
13654 {
13660 {
13669 }
13673 }
13674 }
13676 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13677 attempt to fold the expression to a constant without modifying TYPE,
13678 OP0 or OP1.
13680 If the expression could be simplified to a constant, then return
13681 the constant. If the expression would not be simplified to a
13682 constant, then return NULL_TREE. */
13684 tree
13686 {
13689 }
13691 /* Given the components of a unary expression CODE, TYPE and OP0,
13692 attempt to fold the expression to a constant without modifying
13693 TYPE or OP0.
13695 If the expression could be simplified to a constant, then return
13696 the constant. If the expression would not be simplified to a
13697 constant, then return NULL_TREE. */
13699 tree
13701 {
13704 }
13706 /* If EXP represents referencing an element in a constant string
13707 (either via pointer arithmetic or array indexing), return the
13708 tree representing the value accessed, otherwise return NULL. */
13710 tree
13712 {
13716 {
13718 tree index;
13719 tree string;
13724 else
13725 {
13729 /* Optimize the special-case of a zero lower bound.
13731 We convert the low_bound to sizetype to avoid some problems
13732 with constant folding. (E.g. suppose the lower bound is 1,
13733 and its mode is QI. Without the conversion,l (ARRAY
13734 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13735 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13741 }
13754 }
13756 }
13758 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13759 an integer constant, real, or fixed-point constant.
13761 TYPE is the type of the result. */
13763 static tree
13765 {
13769 {
13771 {
13778 }
13785 {
13786 FIXED_VALUE_TYPE f;
13791 /* Propagate overflow flags. */
13795 }
13799 }
13802 }
13804 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13805 an integer constant or real constant.
13807 TYPE is the type of the result. */
13809 tree
13811 {
13815 {
13817 {
13818 /* If the value is unsigned or non-negative, then the absolute value
13819 is the same as the ordinary value. */
13823 /* If the value is negative, then the absolute value is
13824 its negation. */
13825 else
13826 {
13831 }
13832 }
13838 else
13844 }
13847 }
13849 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13850 constant. TYPE is the type of the result. */
13852 static tree
13854 {
13858 }
13860 /* Given CODE, a relational operator, the target type, TYPE and two
13861 constant operands OP0 and OP1, return the result of the
13862 relational operation. If the result is not a compile time
13863 constant, then return NULL_TREE. */
13865 static tree
13867 {
13870 /* From here on, the only cases we handle are when the result is
13871 known to be a constant. */
13874 {
13878 /* Handle the cases where either operand is a NaN. */
13880 {
13882 {
13910 }
13913 }
13916 }
13919 {
13923 }
13925 /* Handle equality/inequality of complex constants. */
13927 {
13938 else
13940 }
13943 {
13945 {
13946 /* Have vector comparison with scalar boolean result. */
13951 {
13956 }
13960 }
13967 {
13979 }
13982 }
13984 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13986 To compute GT, swap the arguments and do LT.
13987 To compute GE, do LT and invert the result.
13988 To compute LE, swap the arguments, do LT and invert the result.
13989 To compute NE, do EQ and invert the result.
13991 Therefore, the code below must handle only EQ and LT. */
13994 {
13997 }
13999 /* Note that it is safe to invert for real values here because we
14000 have already handled the one case that it matters. */
14004 {
14007 }
14009 /* Compute a result for LT or EQ if args permit;
14010 Otherwise return T. */
14012 {
14015 else
14017 }
14018 else
14024 }
14026 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14027 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14028 itself. */
14030 tree
14032 {
14033 /* If the expression does not have side effects then we don't have to wrap
14034 it with a cleanup point expression. */
14038 /* If the expression is a return, check to see if the expression inside the
14039 return has no side effects or the right hand side of the modify expression
14040 inside the return. If either don't have side effects set we don't need to
14041 wrap the expression in a cleanup point expression. Note we don't check the
14042 left hand side of the modify because it should always be a return decl. */
14044 {
14051 }
14054 }
14056 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14057 of an indirection through OP0, or NULL_TREE if no simplification is
14058 possible. */
14060 tree
14062 {
14064 tree subtype;
14072 {
14075 /* *&CONST_DECL -> to the value of the const decl. */
14078 /* *&p => p; make sure to handle *&"str"[cst] here. */
14080 {
14084 else
14086 }
14087 /* *(foo *)&fooarray => fooarray[0] */
14090 && (!in_gimple_form
14092 {
14102 }
14103 /* *(foo *)&complexfoo => __real__ complexfoo */
14107 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14110 {
14114 }
14115 }
14119 {
14125 {
14126 tree op00type;
14130 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14133 {
14135 unsigned HOST_WIDE_INT max_offset
14140 {
14147 }
14148 }
14149 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14152 {
14156 }
14157 /* ((foo *)&fooarray)[1] => fooarray[1] */
14160 {
14170 }
14171 }
14172 }
14174 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14177 && (!in_gimple_form
14179 {
14180 tree type_domain;
14190 NULL_TREE);
14191 }
14194 }
14196 /* Builds an expression for an indirection through T, simplifying some
14197 cases. */
14199 tree
14201 {
14209 }
14211 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14213 tree
14215 {
14220 else
14222 }
14224 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14225 whose result is ignored. The type of the returned tree need not be
14226 the same as the original expression. */
14228 tree
14230 {
14236 {
14247 else
14253 {
14269 }
14274 }
14275 }
14277 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14279 tree
14281 {
14287 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14288 have to do anything. Only do this when we are not given a const,
14289 because in that case, this check is more expensive than just
14290 doing it. */
14292 {
14297 }
14299 /* If divisor is a power of two, simplify this to bit manipulation. */
14301 {
14303 {
14317 }
14318 else
14319 {
14320 tree t;
14326 }
14327 }
14328 else
14329 {
14334 }
14337 }
14339 /* Likewise, but round down. */
14341 tree
14343 {
14350 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14351 have to do anything. Only do this when we are not given a const,
14352 because in that case, this check is more expensive than just
14353 doing it. */
14355 {
14360 }
14362 /* If divisor is a power of two, simplify this to bit manipulation. */
14364 {
14365 tree t;
14369 }
14370 else
14371 {
14376 }
14379 }
14381 /* Returns the pointer to the base of the object addressed by EXP and
14382 extracts the information about the offset of the access, storing it
14383 to PBITPOS and POFFSET. */
14385 static tree
14388 {
14389 tree core;
14390 machine_mode mode;
14392 HOST_WIDE_INT bitsize;
14396 {
14401 }
14402 else
14403 {
14407 }
14410 }
14412 /* Returns true if addresses of E1 and E2 differ by a constant, false
14413 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14415 bool
14417 {
14431 {
14441 }
14443 {
14444 /* If only one of the offsets is non-constant, the difference cannot
14445 be a constant. */
14447 }
14448 else
14453 }
14455 /* Return OFF converted to a pointer offset type suitable as offset for
14456 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14457 tree
14459 {
14461 }
14463 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14464 tree
14466 {
14469 }
14471 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14472 tree
14474 {
14477 }
14479 /* Return a char pointer for a C string if it is a string constant
14480 or sum of string constant and integer constant. */
14484 {
14485 tree offset_node;
14498 }