| blob | 0cb09f4736e4f9c6bc814c6edabaed8ffa08f3f1 |
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 };
125 HOST_WIDE_INT *,
154 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
155 Otherwise, return LOC. */
157 static location_t
159 {
162 }
164 /* Similar to protected_set_expr_location, but never modify x in place,
165 if location can and needs to be set, unshare it. */
169 {
175 {
178 }
180 }
181 \f
182 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
183 division and returns the quotient. Otherwise returns
184 NULL_TREE. */
186 tree
188 {
189 widest_int quo;
196 }
197 \f
198 /* This is nonzero if we should defer warnings about undefined
199 overflow. This facility exists because these warnings are a
200 special case. The code to estimate loop iterations does not want
201 to issue any warnings, since it works with expressions which do not
202 occur in user code. Various bits of cleanup code call fold(), but
203 only use the result if it has certain characteristics (e.g., is a
204 constant); that code only wants to issue a warning if the result is
205 used. */
209 /* If a warning about undefined overflow is deferred, this is the
210 warning. Note that this may cause us to turn two warnings into
211 one, but that is fine since it is sufficient to only give one
212 warning per expression. */
216 /* If a warning about undefined overflow is deferred, this is the
217 level at which the warning should be emitted. */
221 /* Start deferring overflow warnings. We could use a stack here to
222 permit nested calls, but at present it is not necessary. */
224 void
226 {
228 }
230 /* Stop deferring overflow warnings. If there is a pending warning,
231 and ISSUE is true, then issue the warning if appropriate. STMT is
232 the statement with which the warning should be associated (used for
233 location information); STMT may be NULL. CODE is the level of the
234 warning--a warn_strict_overflow_code value. This function will use
235 the smaller of CODE and the deferred code when deciding whether to
236 issue the warning. CODE may be zero to mean to always use the
237 deferred code. */
239 void
241 {
243 location_t locus;
248 {
254 }
265 /* Use the smallest code level when deciding to issue the
266 warning. */
275 else
278 }
280 /* Stop deferring overflow warnings, ignoring any deferred
281 warnings. */
283 void
285 {
287 }
289 /* Whether we are deferring overflow warnings. */
291 bool
293 {
295 }
297 /* This is called when we fold something based on the fact that signed
298 overflow is undefined. */
300 static void
302 {
304 {
307 {
310 }
311 }
314 }
315 \f
316 /* Return true if the built-in mathematical function specified by CODE
317 is odd, i.e. -f(x) == f(-x). */
319 bool
321 {
323 {
324 CASE_CFN_ASIN:
325 CASE_CFN_ASINH:
326 CASE_CFN_ATAN:
327 CASE_CFN_ATANH:
328 CASE_CFN_CASIN:
329 CASE_CFN_CASINH:
330 CASE_CFN_CATAN:
331 CASE_CFN_CATANH:
332 CASE_CFN_CBRT:
333 CASE_CFN_CPROJ:
334 CASE_CFN_CSIN:
335 CASE_CFN_CSINH:
336 CASE_CFN_CTAN:
337 CASE_CFN_CTANH:
338 CASE_CFN_ERF:
339 CASE_CFN_LLROUND:
340 CASE_CFN_LROUND:
341 CASE_CFN_ROUND:
342 CASE_CFN_SIN:
343 CASE_CFN_SINH:
344 CASE_CFN_TAN:
345 CASE_CFN_TANH:
346 CASE_CFN_TRUNC:
349 CASE_CFN_LLRINT:
350 CASE_CFN_LRINT:
351 CASE_CFN_NEARBYINT:
352 CASE_CFN_RINT:
357 }
359 }
361 /* Check whether we may negate an integer constant T without causing
362 overflow. */
364 bool
366 {
367 tree type;
376 }
378 /* Determine whether an expression T can be cheaply negated using
379 the function negate_expr without introducing undefined overflow. */
381 static bool
383 {
384 tree type;
393 {
398 /* Check that -CST will not overflow type. */
411 /* We want to canonicalize to positive real constants. Pretend
412 that only negative ones can be easily negated. */
420 {
431 }
446 /* -(A + B) -> (-B) - A. */
451 /* -(A + B) -> (-A) - B. */
455 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
466 /* INT_MIN/n * n doesn't overflow while negating one operand it does
467 if n is a power of two. */
476 /* Fall through. */
491 /* In general we can't negate B in A / B, because if A is INT_MIN and
492 B is 1, we may turn this into INT_MIN / -1 which is undefined
493 and actually traps on some architectures. */
502 /* Negate -((double)float) as (double)(-float). */
504 {
508 }
512 /* Negate -f(x) as f(-x). */
518 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
520 {
524 }
529 }
531 }
533 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
534 simplification is possible.
535 If negate_expr_p would return true for T, NULL_TREE will never be
536 returned. */
538 static tree
540 {
542 tree tem;
545 {
546 /* Convert - (~A) to A + 1. */
572 {
577 }
581 {
586 {
590 }
593 }
616 {
617 /* -(A + B) -> (-B) - A. */
621 {
625 }
627 /* -(A + B) -> (-A) - B. */
629 {
633 }
634 }
638 /* - (A - B) -> B - A */
650 /* Fall through. */
654 {
663 }
675 /* In general we can't negate B in A / B, because if A is INT_MIN and
676 B is 1, we may turn this into INT_MIN / -1 which is undefined
677 and actually traps on some architectures. */
689 /* Convert -((double)float) into (double)(-float). */
691 {
695 }
699 /* Negate -f(x) as f(-x). */
702 {
708 }
712 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
714 {
717 {
724 }
725 }
730 }
733 }
735 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
736 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
737 return NULL_TREE. */
739 static tree
741 {
743 location_t loc;
756 }
757 \f
758 /* Split a tree IN into a constant, literal and variable parts that could be
759 combined with CODE to make IN. "constant" means an expression with
760 TREE_CONSTANT but that isn't an actual constant. CODE must be a
761 commutative arithmetic operation. Store the constant part into *CONP,
762 the literal in *LITP and return the variable part. If a part isn't
763 present, set it to null. If the tree does not decompose in this way,
764 return the entire tree as the variable part and the other parts as null.
766 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
767 case, we negate an operand that was subtracted. Except if it is a
768 literal for which we use *MINUS_LITP instead.
770 If NEGATE_P is true, we are negating all of IN, again except a literal
771 for which we use *MINUS_LITP instead. If a variable part is of pointer
772 type, it is negated after converting to TYPE. This prevents us from
773 generating illegal MINUS pointer expression. LOC is the location of
774 the converted variable part.
776 If IN is itself a literal or constant, return it as appropriate.
778 Note that we do not guarantee that any of the three values will be the
779 same type as IN, but they will have the same signedness and mode. */
781 static tree
784 {
791 /* Strip any conversions that don't change the machine mode or signedness. */
800 /* We can associate addition and subtraction together (even
801 though the C standard doesn't say so) for integers because
802 the value is not affected. For reals, the value might be
803 affected, so we can't. */
806 {
812 /* First see if either of the operands is a literal, then a constant. */
825 /* If we haven't dealt with either operand, this is not a case we can
826 decompose. Otherwise, VAR is either of the ones remaining, if any. */
831 else
834 /* Now do any needed negations. */
840 {
841 /* Convert to TYPE before negating. */
844 }
845 }
848 {
849 /* -X - 1 is folded to ~X, undo that here. */
852 }
855 else
859 {
866 {
867 /* Convert to TYPE before negating. */
870 }
871 }
874 }
876 /* Re-associate trees split by the above function. T1 and T2 are
877 either expressions to associate or null. Return the new
878 expression, if any. LOC is the location of the new expression. If
879 we build an operation, do it in TYPE and with CODE. */
881 static tree
883 {
889 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
890 try to fold this since we will have infinite recursion. But do
891 deal with any NEGATE_EXPRs. */
894 {
896 {
909 }
911 {
914 }
918 }
922 }
923 \f
924 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
925 for use in int_const_binop, size_binop and size_diffop. */
927 static bool
929 {
936 {
945 }
950 }
953 /* Combine two integer constants ARG1 and ARG2 under operation CODE
954 to produce a new constant. Return NULL_TREE if we don't know how
955 to evaluate CODE at compile-time. */
957 static tree
960 {
961 wide_int res;
962 tree t;
971 {
987 {
991 else
993 }
996 /* It's unclear from the C standard whether shifts can overflow.
997 The following code ignores overflow; perhaps a C standard
998 interpretation ruling is needed. */
1000 else
1007 {
1011 else
1013 }
1017 else
1096 }
1104 }
1106 tree
1108 {
1110 }
1112 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1113 constant. We assume ARG1 and ARG2 have the same data type, or at least
1114 are the same kind of constant and the same machine mode. Return zero if
1115 combining the constants is not allowed in the current operating mode. */
1117 static tree
1119 {
1120 /* Sanity check for the recursive cases. */
1128 {
1134 }
1137 {
1138 machine_mode mode;
1139 REAL_VALUE_TYPE d1;
1140 REAL_VALUE_TYPE d2;
1141 REAL_VALUE_TYPE value;
1142 REAL_VALUE_TYPE result;
1146 /* The following codes are handled by real_arithmetic. */
1148 {
1159 }
1167 /* Don't perform operation if we honor signaling NaNs and
1168 either operand is a signaling NaN. */
1174 /* Don't perform operation if it would raise a division
1175 by zero exception. */
1181 /* If either operand is a NaN, just return it. Otherwise, set up
1182 for floating-point trap; we return an overflow. */
1184 {
1185 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1186 is off. */
1190 }
1192 {
1193 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1194 is off. */
1198 }
1203 /* Don't constant fold this floating point operation if
1204 the result has overflowed and flag_trapping_math. */
1212 /* Don't constant fold this floating point operation if the
1213 result may dependent upon the run-time rounding mode and
1214 flag_rounding_math is set, or if GCC's software emulation
1215 is unable to accurately represent the result. */
1225 }
1228 {
1229 FIXED_VALUE_TYPE f1;
1230 FIXED_VALUE_TYPE f2;
1231 FIXED_VALUE_TYPE result;
1236 /* The following codes are handled by fixed_arithmetic. */
1238 {
1250 {
1257 }
1262 }
1269 /* Propagate overflow flags. */
1273 }
1276 {
1285 {
1296 mpc_mul);
1310 mpc_div);
1311 /* Fallthru ... */
1317 {
1318 /* Keep this algorithm in sync with
1319 tree-complex.c:expand_complex_div_straight().
1321 Expand complex division to scalars, straightforward algorithm.
1322 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1323 t = br*br + bi*bi
1324 */
1325 tree magsquared
1329 tree t1
1333 tree t2
1340 }
1341 else
1342 {
1343 /* Keep this algorithm in sync with
1344 tree-complex.c:expand_complex_div_wide().
1346 Expand complex division to scalars, modified algorithm to minimize
1347 overflow with wide input ranges. */
1353 {
1354 /* In the TRUE branch, we compute
1355 ratio = br/bi;
1356 div = (br * ratio) + bi;
1357 tr = (ar * ratio) + ai;
1358 ti = (ai * ratio) - ar;
1359 tr = tr / div;
1360 ti = ti / div; */
1371 }
1372 else
1373 {
1374 /* In the FALSE branch, we compute
1375 ratio = d/c;
1376 divisor = (d * ratio) + c;
1377 tr = (b * ratio) + a;
1378 ti = b - (a * ratio);
1379 tr = tr / div;
1380 ti = ti / div; */
1392 }
1393 }
1398 }
1402 }
1406 {
1412 {
1418 /* It is possible that const_binop cannot handle the given
1419 code and return NULL_TREE */
1422 }
1425 }
1427 /* Shifts allow a scalar offset for a vector. */
1430 {
1436 {
1441 /* It is possible that const_binop cannot handle the given
1442 code and return NULL_TREE. */
1445 }
1448 }
1450 }
1452 /* Overload that adds a TYPE parameter to be able to dispatch
1453 to fold_relational_const. */
1455 tree
1457 {
1461 /* ??? Until we make the const_binop worker take the type of the
1462 result as argument put those cases that need it here. */
1464 {
1475 {
1491 {
1497 }
1500 }
1506 {
1531 {
1544 }
1547 }
1550 }
1555 /* Make sure type and arg0 have the same saturating flag. */
1560 }
1562 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1563 Return zero if computing the constants is not possible. */
1565 tree
1567 {
1568 /* Don't perform the operation, other than NEGATE and ABS, if
1569 flag_signaling_nans is on and the operand is a signaling NaN. */
1578 {
1579 CASE_CONVERT:
1586 /* If the source address is 0, and the source address space
1587 cannot have a valid object at 0, fold to dest type null. */
1598 {
1599 /* Can't call fold_negate_const directly here as that doesn't
1600 handle all cases and we might not be able to negate some
1601 constants. */
1606 }
1615 {
1619 }
1625 /* Perform BIT_NOT_EXPR on each element individually. */
1627 {
1629 tree elem;
1634 {
1640 }
1643 }
1665 {
1684 else
1688 {
1692 }
1695 }
1700 {
1714 {
1719 }
1722 {
1726 }
1729 }
1733 }
1736 }
1738 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1739 indicates which particular sizetype to create. */
1741 tree
1743 {
1745 }
1746 \f
1747 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1748 is a tree code. The type of the result is taken from the operands.
1749 Both must be equivalent integer types, ala int_binop_types_match_p.
1750 If the operands are constant, so is the result. */
1752 tree
1754 {
1763 /* Handle the special case of two integer constants faster. */
1765 {
1766 /* And some specific cases even faster than that. */
1768 {
1773 }
1775 {
1778 }
1780 {
1783 }
1785 /* Handle general case of two integer constants. For sizetype
1786 constant calculations we always want to know about overflow,
1787 even in the unsigned case. */
1789 }
1792 }
1794 /* Given two values, either both of sizetype or both of bitsizetype,
1795 compute the difference between the two values. Return the value
1796 in signed type corresponding to the type of the operands. */
1798 tree
1800 {
1802 tree ctype;
1807 /* If the type is already signed, just do the simple thing. */
1815 else
1818 /* If either operand is not a constant, do the conversions to the signed
1819 type and subtract. The hardware will do the right thing with any
1820 overflow in the subtraction. */
1826 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1827 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1828 overflow) and negate (which can't either). Special-case a result
1829 of zero while we're here. */
1835 else
1839 MINUS_EXPR,
1841 }
1842 \f
1843 /* A subroutine of fold_convert_const handling conversions of an
1844 INTEGER_CST to another integer type. */
1846 static tree
1848 {
1849 /* Given an integer constant, make new constant with new type,
1850 appropriately sign-extended or truncated. Use widest_int
1851 so that any extension is done according ARG1's type. */
1855 }
1857 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1858 to an integer type. */
1860 static tree
1862 {
1864 tree t;
1866 /* The following code implements the floating point to integer
1867 conversion rules required by the Java Language Specification,
1868 that IEEE NaNs are mapped to zero and values that overflow
1869 the target precision saturate, i.e. values greater than
1870 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1871 are mapped to INT_MIN. These semantics are allowed by the
1872 C and C++ standards that simply state that the behavior of
1873 FP-to-integer conversion is unspecified upon overflow. */
1875 wide_int val;
1876 REAL_VALUE_TYPE r;
1880 {
1887 }
1889 /* If R is NaN, return zero and show we have an overflow. */
1891 {
1894 }
1896 /* See if R is less than the lower bound or greater than the
1897 upper bound. */
1900 {
1904 {
1907 }
1908 }
1911 {
1914 {
1917 {
1920 }
1921 }
1922 }
1929 }
1931 /* A subroutine of fold_convert_const handling conversions of a
1932 FIXED_CST to an integer type. */
1934 static tree
1936 {
1937 tree t;
1941 /* Right shift FIXED_CST to temp by fbit. */
1945 {
1947 HOST_BITS_PER_DOUBLE_INT,
1950 /* Left shift temp to temp_trunc by fbit. */
1952 HOST_BITS_PER_DOUBLE_INT,
1954 }
1955 else
1956 {
1959 }
1961 /* If FIXED_CST is negative, we need to round the value toward 0.
1962 By checking if the fractional bits are not zero to add 1 to temp. */
1968 /* Given a fixed-point constant, make new constant with new type,
1969 appropriately sign-extended or truncated. */
1977 }
1979 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1980 to another floating point type. */
1982 static tree
1984 {
1985 REAL_VALUE_TYPE value;
1986 tree t;
1988 /* Don't perform the operation if flag_signaling_nans is on
1989 and the operand is a signaling NaN. */
1997 /* If converting an infinity or NAN to a representation that doesn't
1998 have one, set the overflow bit so that we can produce some kind of
1999 error message at the appropriate point if necessary. It's not the
2000 most user-friendly message, but it's better than nothing. */
2007 /* Regular overflow, conversion produced an infinity in a mode that
2008 can't represent them. */
2013 else
2016 }
2018 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2019 to a floating point type. */
2021 static tree
2023 {
2024 REAL_VALUE_TYPE value;
2025 tree t;
2032 }
2034 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2035 to another fixed-point type. */
2037 static tree
2039 {
2040 FIXED_VALUE_TYPE value;
2041 tree t;
2048 /* Propagate overflow flags. */
2052 }
2054 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2055 to a fixed-point type. */
2057 static tree
2059 {
2060 FIXED_VALUE_TYPE value;
2061 tree t;
2063 double_int di;
2070 else
2078 /* Propagate overflow flags. */
2082 }
2084 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2085 to a fixed-point type. */
2087 static tree
2089 {
2090 FIXED_VALUE_TYPE value;
2091 tree t;
2099 /* Propagate overflow flags. */
2103 }
2105 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2106 type TYPE. If no simplification can be done return NULL_TREE. */
2108 static tree
2110 {
2116 {
2123 }
2125 {
2132 }
2134 {
2141 }
2143 {
2146 {
2151 {
2157 }
2159 }
2160 }
2162 }
2164 /* Construct a vector of zero elements of vector type TYPE. */
2166 static tree
2168 {
2169 tree t;
2173 }
2175 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2177 bool
2179 {
2194 {
2210 }
2211 }
2213 /* Convert expression ARG to type TYPE. Used by the middle-end for
2214 simple conversions in preference to calling the front-end's convert. */
2216 tree
2218 {
2220 tree tem;
2231 {
2234 /* Handle conversions between pointers to different address spaces. */
2239 /* fall through */
2244 {
2248 }
2262 {
2266 }
2268 {
2272 }
2274 {
2278 }
2281 {
2299 }
2304 {
2308 }
2311 {
2325 }
2329 {
2338 integer_zero_node));
2340 {
2344 {
2350 }
2358 }
2362 }
2380 }
2381 fold_convert_exit:
2384 }
2385 \f
2386 /* Return false if expr can be assumed not to be an lvalue, true
2387 otherwise. */
2389 static bool
2391 {
2392 /* We only need to wrap lvalue tree codes. */
2394 {
2425 /* Assume the worst for front-end tree codes. */
2429 }
2432 }
2434 /* Return an expr equal to X but certainly not valid as an lvalue. */
2436 tree
2438 {
2439 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2440 us. */
2447 }
2449 /* When pedantic, return an expr equal to X but certainly not valid as a
2450 pedantic lvalue. Otherwise, return X. */
2452 static tree
2454 {
2456 }
2457 \f
2458 /* Given a tree comparison code, return the code that is the logical inverse.
2459 It is generally not safe to do this for floating-point comparisons, except
2460 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2461 ERROR_MARK in this case. */
2463 enum tree_code
2465 {
2471 {
2502 }
2503 }
2505 /* Similar, but return the comparison that results if the operands are
2506 swapped. This is safe for floating-point. */
2508 enum tree_code
2510 {
2512 {
2538 }
2539 }
2542 /* Convert a comparison tree code from an enum tree_code representation
2543 into a compcode bit-based encoding. This function is the inverse of
2544 compcode_to_comparison. */
2546 static enum comparison_code
2548 {
2550 {
2581 }
2582 }
2584 /* Convert a compcode bit-based encoding of a comparison operator back
2585 to GCC's enum tree_code representation. This function is the
2586 inverse of comparison_to_compcode. */
2588 static enum tree_code
2590 {
2592 {
2623 }
2624 }
2626 /* Return a tree for the comparison which is the combination of
2627 doing the AND or OR (depending on CODE) of the two operations LCODE
2628 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2629 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2630 if this makes the transformation invalid. */
2632 tree
2637 {
2644 {
2655 }
2658 {
2659 /* Eliminate unordered comparisons, as well as LTGT and ORD
2660 which are not used unless the mode has NaNs. */
2666 }
2668 {
2669 /* Check that the original operation and the optimized ones will trap
2670 under the same condition. */
2681 /* In a short-circuited boolean expression the LHS might be
2682 such that the RHS, if evaluated, will never trap. For
2683 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2684 if neither x nor y is NaN. (This is a mixed blessing: for
2685 example, the expression above will never trap, hence
2686 optimizing it to x < y would be invalid). */
2691 /* If the comparison was short-circuited, and only the RHS
2692 trapped, we may now generate a spurious trap. */
2697 /* If we changed the conditions that cause a trap, we lose. */
2700 }
2706 else
2707 {
2712 }
2713 }
2714 \f
2715 /* Return nonzero if two operands (typically of the same tree node)
2716 are necessarily equal. FLAGS modifies behavior as follows:
2718 If OEP_ONLY_CONST is set, only return nonzero for constants.
2719 This function tests whether the operands are indistinguishable;
2720 it does not test whether they are equal using C's == operation.
2721 The distinction is important for IEEE floating point, because
2722 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2723 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2725 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2726 even though it may hold multiple values during a function.
2727 This is because a GCC tree node guarantees that nothing else is
2728 executed between the evaluation of its "operands" (which may often
2729 be evaluated in arbitrary order). Hence if the operands themselves
2730 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2731 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2732 unset means assuming isochronic (or instantaneous) tree equivalence.
2733 Unless comparing arbitrary expression trees, such as from different
2734 statements, this flag can usually be left unset.
2736 If OEP_PURE_SAME is set, then pure functions with identical arguments
2737 are considered the same. It is used when the caller has other ways
2738 to ensure that global memory is unchanged in between.
2740 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2741 not values of expressions.
2743 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2744 any operand with side effect. This is unnecesarily conservative in the
2745 case we know that arg0 and arg1 are in disjoint code paths (such as in
2746 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2747 addresses with TREE_CONSTANT flag set so we know that &var == &var
2748 even if var is volatile. */
2750 int
2752 {
2753 /* If either is ERROR_MARK, they aren't equal. */
2759 /* Similar, if either does not have a type (like a released SSA name),
2760 they aren't equal. */
2764 /* We cannot consider pointers to different address space equal. */
2771 /* Check equality of integer constants before bailing out due to
2772 precision differences. */
2774 {
2775 /* Address of INTEGER_CST is not defined; check that we did not forget
2776 to drop the OEP_ADDRESS_OF flags. */
2779 }
2782 {
2783 /* If both types don't have the same signedness, then we can't consider
2784 them equal. We must check this before the STRIP_NOPS calls
2785 because they may change the signedness of the arguments. As pointers
2786 strictly don't have a signedness, require either two pointers or
2787 two non-pointers as well. */
2793 /* If both types don't have the same precision, then it is not safe
2794 to strip NOPs. */
2801 }
2802 #if 0
2803 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2804 sanity check once the issue is solved. */
2805 else
2806 /* Addresses of conversions and SSA_NAMEs (and many other things)
2807 are not defined. Check that we did not forget to drop the
2808 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2811 #endif
2813 /* In case both args are comparisons but with different comparison
2814 code, try to swap the comparison operands of one arg to produce
2815 a match and compare that variant. */
2819 {
2827 }
2830 {
2831 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2833 ;
2835 {
2836 /* If we are interested in comparing addresses ignore
2837 MEM_REF wrappings of the base that can appear just for
2838 TBAA reasons. */
2852 }
2853 else
2855 }
2857 /* When not checking adddresses, this is needed for conversions and for
2858 COMPONENT_REF. Might as well play it safe and always test this. */
2865 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2866 We don't care about side effects in that case because the SAVE_EXPR
2867 takes care of that for us. In all other cases, two expressions are
2868 equal if they have no side effects. If we have two identical
2869 expressions with side effects that should be treated the same due
2870 to the only side effects being identical SAVE_EXPR's, that will
2871 be detected in the recursive calls below.
2872 If we are taking an invariant address of two identical objects
2873 they are necessarily equal as well. */
2880 /* Next handle constant cases, those for which we can return 1 even
2881 if ONLY_CONST is set. */
2884 {
2898 {
2899 /* If we do not distinguish between signed and unsigned zero,
2900 consider them equal. */
2903 }
2907 {
2914 {
2918 }
2920 }
2924 flags)
2926 flags));
2937 flags | OEP_ADDRESS_OF
2940 /* In GIMPLE empty constructors are allowed in initializers of
2941 aggregates. */
2946 }
2951 /* Define macros to test an operand from arg0 and arg1 for equality and a
2952 variant that allows null and views null as being different from any
2953 non-null value. In the latter case, if either is null, the both
2954 must be; otherwise, do the normal comparison. */
2955 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2956 TREE_OPERAND (arg1, N), flags)
2958 #define OP_SAME_WITH_NULL(N) \
2959 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2960 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2963 {
2965 /* Two conversions are equal only if signedness and modes match. */
2967 {
2968 CASE_CONVERT:
2976 }
2986 /* For commutative ops, allow the other order. */
2994 /* If either of the pointer (or reference) expressions we are
2995 dereferencing contain a side effect, these cannot be equal,
2996 but their addresses can be. */
3003 {
3013 /* Require the same offset. */
3019 /* Fallthru. */
3027 {
3028 /* Require equal access sizes */
3034 flags)))
3036 /* Verify that access happens in similar types. */
3039 /* Verify that accesses are TBAA compatible. */
3048 /* Verify that alignment is compatible. */
3052 }
3055 /* TARGET_MEM_REF require equal extra operands. */
3066 /* Compare the array index by value if it is constant first as we
3067 may have different types but same value here. */
3073 /* Compare low bound and element size as with OEP_ADDRESS_OF
3074 we have to account for the offset of the ref. */
3079 array_ref_low_bound
3083 array_ref_element_size
3085 flags))));
3088 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3089 may be NULL when we're called to compare MEM_EXPRs. */
3104 }
3108 {
3110 /* Be sure we pass right ADDRESS_OF flag. */
3128 /* The multiplcation operands are commutative. */
3129 /* FALLTHRU */
3137 /* Otherwise take into account this is a commutative operation. */
3155 }
3159 {
3163 /* If not both CALL_EXPRs are either internal or normal function
3164 functions, then they are not equal. */
3167 {
3168 /* If the CALL_EXPRs call different internal functions, then they
3169 are not equal. */
3172 }
3173 else
3174 {
3175 /* If the CALL_EXPRs call different functions, then they are not
3176 equal. */
3178 flags))
3180 }
3182 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3183 {
3187 else
3191 }
3193 /* Now see if all the arguments are the same. */
3194 {
3205 /* If we get here and both argument lists are exhausted
3206 then the CALL_EXPRs are equal. */
3208 }
3211 }
3214 /* Consider __builtin_sqrt equal to sqrt. */
3222 {
3223 /* In GIMPLE constructors are used only to build vectors from
3224 elements. Individual elements in the constructor must be
3225 indexed in increasing order and form an initial sequence.
3227 We make no effort to compare constructors in generic.
3228 (see sem_variable::equals in ipa-icf which can do so for
3229 constants). */
3234 /* Be sure that vectors constructed have the same representation.
3235 We only tested element precision and modes to match.
3236 Vectors may be BLKmode and thus also check that the number of
3237 parts match. */
3250 {
3255 /* In GIMPLE the indexes can be either NULL or matching i.
3256 Double check this so we won't get false
3257 positives for GENERIC. */
3265 }
3267 }
3272 }
3274 #undef OP_SAME
3275 #undef OP_SAME_WITH_NULL
3276 }
3277 \f
3278 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3279 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3281 When in doubt, return 0. */
3283 static int
3285 {
3297 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3298 and see if the inner values are the same. This removes any
3299 signedness comparison, which doesn't matter here. */
3306 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3307 actual comparison operand, ARG0.
3309 First throw away any conversions to wider types
3310 already present in the operands. */
3319 {
3322 /* Make sure shorter operand is extended the right way
3323 to match the longer operand. */
3329 }
3332 }
3333 \f
3334 /* See if ARG is an expression that is either a comparison or is performing
3335 arithmetic on comparisons. The comparisons must only be comparing
3336 two different values, which will be stored in *CVAL1 and *CVAL2; if
3337 they are nonzero it means that some operands have already been found.
3338 No variables may be used anywhere else in the expression except in the
3339 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3340 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3342 If this is true, return 1. Otherwise, return zero. */
3344 static int
3346 {
3350 /* We can handle some of the tcc_expression cases here. */
3360 {
3361 /* If we've already found a CVAL1 or CVAL2, this expression is
3362 two complex to handle. */
3368 }
3371 {
3394 /* First see if we can handle the first operand, then the second. For
3395 the second operand, we know *CVAL1 can't be zero. It must be that
3396 one side of the comparison is each of the values; test for the
3397 case where this isn't true by failing if the two operands
3398 are the same. */
3407 ;
3411 ;
3412 else
3416 ;
3420 ;
3421 else
3428 }
3429 }
3430 \f
3431 /* ARG is a tree that is known to contain just arithmetic operations and
3432 comparisons. Evaluate the operations in the tree substituting NEW0 for
3433 any occurrence of OLD0 as an operand of a comparison and likewise for
3434 NEW1 and OLD1. */
3436 static tree
3439 {
3444 /* We can handle some of the tcc_expression cases here. */
3452 {
3467 {
3486 }
3487 /* Fall through - ??? */
3490 {
3494 /* We need to check both for exact equality and tree equality. The
3495 former will be true if the operand has a side-effect. In that
3496 case, we know the operand occurred exactly once. */
3509 }
3513 }
3514 }
3515 \f
3516 /* Return a tree for the case when the result of an expression is RESULT
3517 converted to TYPE and OMITTED was previously an operand of the expression
3518 but is now not needed (e.g., we folded OMITTED * 0).
3520 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3521 the conversion of RESULT to TYPE. */
3523 tree
3525 {
3528 /* If the resulting operand is an empty statement, just return the omitted
3529 statement casted to void. */
3539 }
3541 /* Return a tree for the case when the result of an expression is RESULT
3542 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3543 of the expression but are now not needed.
3545 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3546 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3547 evaluated before OMITTED2. Otherwise, if neither has side effects,
3548 just do the conversion of RESULT to TYPE. */
3550 tree
3553 {
3562 }
3564 \f
3565 /* Return a simplified tree node for the truth-negation of ARG. This
3566 never alters ARG itself. We assume that ARG is an operation that
3567 returns a truth value (0 or 1).
3569 FIXME: one would think we would fold the result, but it causes
3570 problems with the dominator optimizer. */
3572 static tree
3574 {
3579 /* If this is a comparison, we can simply invert it, except for
3580 floating-point non-equality comparisons, in which case we just
3581 enclose a TRUTH_NOT_EXPR around what we have. */
3584 {
3587 && flag_trapping_math
3601 }
3604 {
3623 /* Here we can invert either operand. We invert the first operand
3624 unless the second operand is a TRUTH_NOT_EXPR in which case our
3625 result is the XOR of the first operand with the inside of the
3626 negation of the second operand. */
3631 else
3654 {
3661 /* A COND_EXPR may have a throw as one operand, which
3662 then has void type. Just leave void operands
3663 as they are. */
3669 }
3681 CASE_CONVERT:
3685 /* ... fall through ... */
3707 }
3708 }
3710 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3711 assume that ARG is an operation that returns a truth value (0 or 1
3712 for scalars, 0 or -1 for vectors). Return the folded expression if
3713 folding is successful. Otherwise, return NULL_TREE. */
3715 static tree
3717 {
3720 ? BIT_NOT_EXPR
3723 }
3725 /* Return a simplified tree node for the truth-negation of ARG. This
3726 never alters ARG itself. We assume that ARG is an operation that
3727 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3729 tree
3731 {
3737 ? BIT_NOT_EXPR
3740 }
3742 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3743 with code CODE. This optimization is unsafe. */
3744 static tree
3747 {
3751 /* (A / C) +- (B / C) -> (A +- B) / C. */
3761 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3766 {
3778 }
3781 }
3782 \f
3783 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3784 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3785 and uses reverse storage order if REVERSEP is nonzero. */
3787 static tree
3791 {
3795 {
3802 }
3817 }
3819 /* Optimize a bit-field compare.
3821 There are two cases: First is a compare against a constant and the
3822 second is a comparison of two items where the fields are at the same
3823 bit position relative to the start of a chunk (byte, halfword, word)
3824 large enough to contain it. In these cases we can avoid the shift
3825 implicit in bitfield extractions.
3827 For constants, we emit a compare of the shifted constant with the
3828 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3829 compared. For two fields at the same position, we do the ANDs with the
3830 similar mask and compare the result of the ANDs.
3832 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3833 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3834 are the left and right operands of the comparison, respectively.
3836 If the optimization described above can be done, we return the resulting
3837 tree. Otherwise we return zero. */
3839 static tree
3842 {
3845 tree unsigned_type;
3852 tree mask;
3853 tree offset;
3855 /* Get all the information about the extractions being done. If the bit size
3856 if the same as the size of the underlying object, we aren't doing an
3857 extraction at all and so can do nothing. We also don't want to
3858 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3859 then will no longer be able to replace it. */
3868 else
3869 {
3870 /* If this is not a constant, we can only do something if bit positions,
3871 sizes, signedness and storage order are the same. */
3872 rinner
3880 }
3882 /* See if we can find a mode to refer to this field. We should be able to,
3883 but fail if we can't. */
3892 /* Set signed and unsigned types of the precision of this mode for the
3893 shifts below. */
3896 /* Compute the bit position and size for the new reference and our offset
3897 within it. If the new reference is the same size as the original, we
3898 won't optimize anything, so return zero. */
3908 /* Make the mask to be used against the extracted field. */
3915 /* If not comparing with constant, just rework the comparison
3916 and return. */
3920 unsigned_type,
3923 mask),
3926 unsigned_type,
3929 mask));
3931 /* Otherwise, we are handling the constant case. See if the constant is too
3932 big for the field. Warn and return a tree for 0 (false) if so. We do
3933 this not only for its own sake, but to avoid having to test for this
3934 error case below. If we didn't, we might generate wrong code.
3936 For unsigned fields, the constant shifted right by the field length should
3937 be all zero. For signed fields, the high-order bits should agree with
3938 the sign bit. */
3941 {
3943 {
3947 }
3948 }
3949 else
3950 {
3953 {
3957 }
3958 }
3960 /* Single-bit compares should always be against zero. */
3962 {
3965 }
3967 /* Make a new bitfield reference, shift the constant over the
3968 appropriate number of bits and mask it with the computed mask
3969 (in case this was a signed field). If we changed it, make a new one. */
3971 lreversep);
3977 mask);
3982 }
3983 \f
3984 /* Subroutine for fold_truth_andor_1: decode a field reference.
3986 If EXP is a comparison reference, we return the innermost reference.
3988 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3989 set to the starting bit number.
3991 If the innermost field can be completely contained in a mode-sized
3992 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3994 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3995 otherwise it is not changed.
3997 *PUNSIGNEDP is set to the signedness of the field.
3999 *PREVERSEP is set to the storage order of the field.
4001 *PMASK is set to the mask used. This is either contained in a
4002 BIT_AND_EXPR or derived from the width of the field.
4004 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4006 Return 0 if this is not a component reference or is one that we can't
4007 do anything with. */
4009 static tree
4014 {
4018 tree unsigned_type;
4021 /* All the optimizations using this function assume integer fields.
4022 There are problems with FP fields since the type_for_size call
4023 below can fail for, e.g., XFmode. */
4027 /* We are interested in the bare arrangement of bits, so strip everything
4028 that doesn't affect the machine mode. However, record the type of the
4029 outermost expression if it may matter below. */
4036 {
4042 }
4051 /* If the number of bits in the reference is the same as the bitsize of
4052 the outer type, then the outer type gives the signedness. Otherwise
4053 (in case of a small bitfield) the signedness is unchanged. */
4057 /* Compute the mask to access the bitfield. */
4066 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4074 }
4076 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4077 bit positions and MASK is SIGNED. */
4079 static int
4081 {
4085 /* If this function returns true when the type of the mask is
4086 UNSIGNED, then there will be errors. In particular see
4087 gcc.c-torture/execute/990326-1.c. There does not appear to be
4088 any documentation paper trail as to why this is so. But the pre
4089 wide-int worked with that restriction and it has been preserved
4090 here. */
4095 }
4097 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4098 represents the sign bit of EXP's type. If EXP represents a sign
4099 or zero extension, also test VAL against the unextended type.
4100 The return value is the (sub)expression whose sign bit is VAL,
4101 or NULL_TREE otherwise. */
4103 tree
4105 {
4107 tree t;
4109 /* Tree EXP must have an integral type. */
4114 /* Tree VAL must be an integer constant. */
4123 /* Handle extension from a narrower type. */
4129 }
4131 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4132 to be evaluated unconditionally. */
4134 static int
4136 {
4137 /* Strip any conversions that don't change the machine mode. */
4146 /* Don't regard global variables as simple. They may be
4147 allocated in ways unknown to the compiler (shared memory,
4148 #pragma weak, etc). */
4151 /* Weakrefs are not safe to be read, since they can be NULL.
4152 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4153 have DECL_WEAK flag set. */
4155 /* Loading a static variable is unduly expensive, but global
4156 registers aren't expensive. */
4158 }
4160 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4161 to be evaluated unconditionally.
4162 I addition to simple_operand_p, we assume that comparisons, conversions,
4163 and logic-not operations are simple, if their operands are simple, too. */
4165 static bool
4167 {
4187 }
4189 \f
4190 /* The following functions are subroutines to fold_range_test and allow it to
4191 try to change a logical combination of comparisons into a range test.
4193 For example, both
4194 X == 2 || X == 3 || X == 4 || X == 5
4195 and
4196 X >= 2 && X <= 5
4197 are converted to
4198 (unsigned) (X - 2) <= 3
4200 We describe each set of comparisons as being either inside or outside
4201 a range, using a variable named like IN_P, and then describe the
4202 range with a lower and upper bound. If one of the bounds is omitted,
4203 it represents either the highest or lowest value of the type.
4205 In the comments below, we represent a range by two numbers in brackets
4206 preceded by a "+" to designate being inside that range, or a "-" to
4207 designate being outside that range, so the condition can be inverted by
4208 flipping the prefix. An omitted bound is represented by a "-". For
4209 example, "- [-, 10]" means being outside the range starting at the lowest
4210 possible value and ending at 10, in other words, being greater than 10.
4211 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4212 always false.
4214 We set up things so that the missing bounds are handled in a consistent
4215 manner so neither a missing bound nor "true" and "false" need to be
4216 handled using a special case. */
4218 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4219 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4220 and UPPER1_P are nonzero if the respective argument is an upper bound
4221 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4222 must be specified for a comparison. ARG1 will be converted to ARG0's
4223 type if both are specified. */
4225 static tree
4228 {
4229 tree tem;
4233 /* If neither arg represents infinity, do the normal operation.
4234 Else, if not a comparison, return infinity. Else handle the special
4235 comparison rules. Note that most of the cases below won't occur, but
4236 are handled for consistency. */
4239 {
4244 }
4249 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4250 for neither. In real maths, we cannot assume open ended ranges are
4251 the same. But, this is computer arithmetic, where numbers are finite.
4252 We can therefore make the transformation of any unbounded range with
4253 the value Z, Z being greater than any representable number. This permits
4254 us to treat unbounded ranges as equal. */
4258 {
4279 }
4282 }
4283 \f
4284 /* Helper routine for make_range. Perform one step for it, return
4285 new expression if the loop should continue or NULL_TREE if it should
4286 stop. */
4288 tree
4292 {
4298 {
4300 /* We can only do something if the range is testing for zero. */
4309 /* We can only do something if the range is testing for zero
4310 and if the second operand is an integer constant. Note that
4311 saying something is "in" the range we make is done by
4312 complementing IN_P since it will set in the initial case of
4313 being not equal to zero; "out" is leaving it alone. */
4320 {
4341 }
4343 /* If this is an unsigned comparison, we also know that EXP is
4344 greater than or equal to zero. We base the range tests we make
4345 on that fact, so we record it here so we can parse existing
4346 range tests. We test arg0_type since often the return type
4347 of, e.g. EQ_EXPR, is boolean. */
4349 {
4353 NULL_TREE))
4358 /* If the high bound is missing, but we have a nonzero low
4359 bound, reverse the range so it goes from zero to the low bound
4360 minus 1. */
4362 {
4367 }
4368 }
4376 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4377 low and high are non-NULL, then normalize will DTRT. */
4380 {
4385 }
4387 /* (-x) IN [a,b] -> x in [-b, -a] */
4399 /* ~ X -> -X - 1 */
4408 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4409 move a constant to the other side. */
4414 /* If EXP is signed, any overflow in the computation is undefined,
4415 so we don't worry about it so long as our computations on
4416 the bounds don't overflow. For unsigned, overflow is defined
4417 and this is exactly the right thing. */
4429 normalize:
4430 /* Check for an unsigned range which has wrapped around the maximum
4431 value thus making n_high < n_low, and normalize it. */
4433 {
4439 /* If the range is of the form +/- [ x+1, x ], we won't
4440 be able to normalize it. But then, it represents the
4441 whole range or the empty set, so make it
4442 +/- [ -, - ]. */
4446 else
4448 }
4449 else
4457 CASE_CONVERT:
4475 /* If we're converting arg0 from an unsigned type, to exp,
4476 a signed type, we will be doing the comparison as unsigned.
4477 The tests above have already verified that LOW and HIGH
4478 are both positive.
4480 So we have to ensure that we will handle large unsigned
4481 values the same way that the current signed bounds treat
4482 negative values. */
4485 {
4486 tree high_positive;
4487 tree equiv_type;
4488 /* For fixed-point modes, we need to pass the saturating flag
4489 as the 2nd parameter. */
4491 equiv_type
4494 else
4495 equiv_type
4498 /* A range without an upper bound is, naturally, unbounded.
4499 Since convert would have cropped a very large value, use
4500 the max value for the destination type. */
4501 high_positive
4508 high_positive),
4511 /* If the low bound is specified, "and" the range with the
4512 range for which the original unsigned value will be
4513 positive. */
4515 {
4518 integer_zero_node),
4519 high_positive))
4523 }
4524 else
4525 {
4526 /* Otherwise, "or" the range with the range of the input
4527 that will be interpreted as negative. */
4530 integer_zero_node),
4531 high_positive))
4535 }
4536 }
4545 }
4546 }
4548 /* Given EXP, a logical expression, set the range it is testing into
4549 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4550 actually being tested. *PLOW and *PHIGH will be made of the same
4551 type as the returned expression. If EXP is not a comparison, we
4552 will most likely not be returning a useful value and range. Set
4553 *STRICT_OVERFLOW_P to true if the return value is only valid
4554 because signed overflow is undefined; otherwise, do not change
4555 *STRICT_OVERFLOW_P. */
4557 tree
4560 {
4568 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4569 and see if we can refine the range. Some of the cases below may not
4570 happen, but it doesn't seem worth worrying about this. We "continue"
4571 the outer loop when we've changed something; otherwise we "break"
4572 the switch, which will "break" the while. */
4578 {
4584 {
4592 }
4601 }
4603 /* If EXP is a constant, we can evaluate whether this is true or false. */
4605 {
4612 }
4616 }
4617 \f
4618 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4619 type, TYPE, return an expression to test if EXP is in (or out of, depending
4620 on IN_P) the range. Return 0 if the test couldn't be created. */
4622 tree
4625 {
4628 /* Disable this optimization for function pointer expressions
4629 on targets that require function pointer canonicalization. */
4636 {
4642 }
4660 {
4662 {
4666 }
4668 }
4670 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4672 {
4676 {
4678 {
4681 etype
4683 else
4686 }
4689 }
4690 }
4692 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4693 This requires wrap-around arithmetics for the type of the expression.
4694 First make sure that arithmetics in this type is valid, then make sure
4695 that it wraps around. */
4701 {
4704 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4705 for the type in question, as we rely on this here. */
4715 else
4717 }
4727 {
4729 {
4734 }
4736 }
4744 }
4745 \f
4746 /* Return the predecessor of VAL in its type, handling the infinite case. */
4748 static tree
4750 {
4756 else
4759 }
4761 /* Return the successor of VAL in its type, handling the infinite case. */
4763 static tree
4765 {
4771 else
4774 }
4776 /* Given two ranges, see if we can merge them into one. Return 1 if we
4777 can, 0 if we can't. Set the output range into the specified parameters. */
4779 bool
4782 {
4786 tree tem;
4796 /* Make range 0 be the range that starts first, or ends last if they
4797 start at the same value. Swap them if it isn't. */
4800 || (lowequal
4803 {
4807 }
4809 /* Now flag two cases, whether the ranges are disjoint or whether the
4810 second range is totally subsumed in the first. Note that the tests
4811 below are simplified by the ones above. */
4817 /* We now have four cases, depending on whether we are including or
4818 excluding the two ranges. */
4820 {
4821 /* If they don't overlap, the result is false. If the second range
4822 is a subset it is the result. Otherwise, the range is from the start
4823 of the second to the end of the first. */
4828 else
4830 }
4833 {
4834 /* If they don't overlap, the result is the first range. If they are
4835 equal, the result is false. If the second range is a subset of the
4836 first, and the ranges begin at the same place, we go from just after
4837 the end of the second range to the end of the first. If the second
4838 range is not a subset of the first, or if it is a subset and both
4839 ranges end at the same place, the range starts at the start of the
4840 first range and ends just before the second range.
4841 Otherwise, we can't describe this as a single range. */
4847 {
4852 {
4853 /* We are in the weird situation where high0 > high1 but
4854 high1 has no successor. Punt. */
4856 }
4857 }
4859 {
4864 {
4865 /* low0 < low1 but low1 has no predecessor. Punt. */
4867 }
4868 }
4869 else
4871 }
4874 {
4875 /* If they don't overlap, the result is the second range. If the second
4876 is a subset of the first, the result is false. Otherwise,
4877 the range starts just after the first range and ends at the
4878 end of the second. */
4883 else
4884 {
4889 {
4890 /* high1 > high0 but high0 has no successor. Punt. */
4892 }
4893 }
4894 }
4896 else
4897 {
4898 /* The case where we are excluding both ranges. Here the complex case
4899 is if they don't overlap. In that case, the only time we have a
4900 range is if they are adjacent. If the second is a subset of the
4901 first, the result is the first. Otherwise, the range to exclude
4902 starts at the beginning of the first range and ends at the end of the
4903 second. */
4905 {
4910 else
4911 {
4912 /* Canonicalize - [min, x] into - [-, x]. */
4915 {
4920 /* FALLTHROUGH */
4933 }
4935 /* Canonicalize - [x, max] into - [x, -]. */
4938 {
4943 /* FALLTHROUGH */
4959 }
4961 /* The ranges might be also adjacent between the maximum and
4962 minimum values of the given type. For
4963 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4964 return + [x + 1, y - 1]. */
4966 {
4973 }
4974 else
4976 }
4977 }
4980 else
4982 }
4986 }
4987 \f
4989 /* Subroutine of fold, looking inside expressions of the form
4990 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4991 of the COND_EXPR. This function is being used also to optimize
4992 A op B ? C : A, by reversing the comparison first.
4994 Return a folded expression whose code is not a COND_EXPR
4995 anymore, or NULL_TREE if no folding opportunity is found. */
4997 static tree
5000 {
5005 tree tem;
5010 /* If we have A op 0 ? A : -A, consider applying the following
5011 transformations:
5013 A == 0? A : -A same as -A
5014 A != 0? A : -A same as A
5015 A >= 0? A : -A same as abs (A)
5016 A > 0? A : -A same as abs (A)
5017 A <= 0? A : -A same as -abs (A)
5018 A < 0? A : -A same as -abs (A)
5020 None of these transformations work for modes with signed
5021 zeros. If A is +/-0, the first two transformations will
5022 change the sign of the result (from +0 to -0, or vice
5023 versa). The last four will fix the sign of the result,
5024 even though the original expressions could be positive or
5025 negative, depending on the sign of A.
5027 Note that all these transformations are correct if A is
5028 NaN, since the two alternatives (A and -A) are also NaNs. */
5035 /* In the case that A is of the form X-Y, '-A' (arg2) may
5036 have already been folded to Y-X, check for that. */
5044 {
5058 /* Fall through. */
5078 }
5080 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5081 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5082 both transformations are correct when A is NaN: A != 0
5083 is then true, and A == 0 is false. */
5087 {
5092 }
5094 /* Try some transformations of A op B ? A : B.
5096 A == B? A : B same as B
5097 A != B? A : B same as A
5098 A >= B? A : B same as max (A, B)
5099 A > B? A : B same as max (B, A)
5100 A <= B? A : B same as min (A, B)
5101 A < B? A : B same as min (B, A)
5103 As above, these transformations don't work in the presence
5104 of signed zeros. For example, if A and B are zeros of
5105 opposite sign, the first two transformations will change
5106 the sign of the result. In the last four, the original
5107 expressions give different results for (A=+0, B=-0) and
5108 (A=-0, B=+0), but the transformed expressions do not.
5110 The first two transformations are correct if either A or B
5111 is a NaN. In the first transformation, the condition will
5112 be false, and B will indeed be chosen. In the case of the
5113 second transformation, the condition A != B will be true,
5114 and A will be chosen.
5116 The conversions to max() and min() are not correct if B is
5117 a number and A is not. The conditions in the original
5118 expressions will be false, so all four give B. The min()
5119 and max() versions would give a NaN instead. */
5122 /* Avoid these transformations if the COND_EXPR may be used
5123 as an lvalue in the C++ front-end. PR c++/19199. */
5124 && (in_gimple_form
5130 {
5135 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5137 {
5141 }
5144 {
5153 /* In C++ a ?: expression can be an lvalue, so put the
5154 operand which will be used if they are equal first
5155 so that we can convert this back to the
5156 corresponding COND_EXPR. */
5158 {
5167 }
5174 {
5183 }
5198 }
5199 }
5201 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5202 we might still be able to simplify this. For example,
5203 if C1 is one less or one more than C2, this might have started
5204 out as a MIN or MAX and been transformed by this function.
5205 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5211 {
5215 /* We can replace A with C1 in this case. */
5220 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5221 MIN_EXPR, to preserve the signedness of the comparison. */
5223 OEP_ONLY_CONST)
5227 OEP_ONLY_CONST))
5228 {
5231 arg2));
5234 }
5238 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5239 as above. */
5241 OEP_ONLY_CONST)
5245 OEP_ONLY_CONST))
5246 {
5249 arg2));
5252 }
5256 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5257 MAX_EXPR, to preserve the signedness of the comparison. */
5259 OEP_ONLY_CONST)
5263 OEP_ONLY_CONST))
5264 {
5267 arg2));
5269 }
5273 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5275 OEP_ONLY_CONST)
5279 OEP_ONLY_CONST))
5280 {
5283 arg2));
5285 }
5291 }
5294 }
5297 \f
5298 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5299 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5300 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5301 false) >= 2)
5302 #endif
5304 /* EXP is some logical combination of boolean tests. See if we can
5305 merge it into some range test. Return the new tree if so. */
5307 static tree
5310 {
5326 /* If this is an OR operation, invert both sides; we will invert
5327 again at the end. */
5331 /* If both expressions are the same, if we can merge the ranges, and we
5332 can build the range test, return it or it inverted. If one of the
5333 ranges is always true or always false, consider it to be the same
5334 expression as the other. */
5342 {
5346 }
5348 /* On machines where the branch cost is expensive, if this is a
5349 short-circuited branch and the underlying object on both sides
5350 is the same, make a non-short-circuit operation. */
5356 {
5357 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5358 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5359 which cases we can't do this. */
5367 {
5376 {
5379 WARN_STRICT_OVERFLOW_COMPARISON);
5383 }
5384 }
5385 }
5388 }
5389 \f
5390 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5391 bit value. Arrange things so the extra bits will be set to zero if and
5392 only if C is signed-extended to its full width. If MASK is nonzero,
5393 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5395 static tree
5397 {
5400 tree temp;
5405 /* We work by getting just the sign bit into the low-order bit, then
5406 into the high-order bit, then sign-extend. We then XOR that value
5407 with C. */
5410 /* We must use a signed type in order to get an arithmetic right shift.
5411 However, we must also avoid introducing accidental overflows, so that
5412 a subsequent call to integer_zerop will work. Hence we must
5413 do the type conversion here. At this point, the constant is either
5414 zero or one, and the conversion to a signed type can never overflow.
5415 We could get an overflow if this conversion is done anywhere else. */
5424 /* If necessary, convert the type back to match the type of C. */
5429 }
5430 \f
5431 /* For an expression that has the form
5432 (A && B) || ~B
5433 or
5434 (A || B) && ~B,
5435 we can drop one of the inner expressions and simplify to
5436 A || ~B
5437 or
5438 A && ~B
5439 LOC is the location of the resulting expression. OP is the inner
5440 logical operation; the left-hand side in the examples above, while CMPOP
5441 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5442 removing a condition that guards another, as in
5443 (A != NULL && A->...) || A == NULL
5444 which we must not transform. If RHS_ONLY is true, only eliminate the
5445 right-most operand of the inner logical operation. */
5447 static tree
5450 {
5468 {
5471 {
5474 }
5475 }
5477 {
5480 {
5483 }
5484 }
5499 }
5501 /* Find ways of folding logical expressions of LHS and RHS:
5502 Try to merge two comparisons to the same innermost item.
5503 Look for range tests like "ch >= '0' && ch <= '9'".
5504 Look for combinations of simple terms on machines with expensive branches
5505 and evaluate the RHS unconditionally.
5507 For example, if we have p->a == 2 && p->b == 4 and we can make an
5508 object large enough to span both A and B, we can do this with a comparison
5509 against the object ANDed with the a mask.
5511 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5512 operations to do this with one comparison.
5514 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5515 function and the one above.
5517 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5518 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5520 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5521 two operands.
5523 We return the simplified tree or 0 if no optimization is possible. */
5525 static tree
5528 {
5529 /* If this is the "or" of two comparisons, we can do something if
5530 the comparisons are NE_EXPR. If this is the "and", we can do something
5531 if the comparisons are EQ_EXPR. I.e.,
5532 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5534 WANTED_CODE is this operation code. For single bit fields, we can
5535 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5536 comparison for one-bit fields. */
5557 /* Start by getting the comparison codes. Fail if anything is volatile.
5558 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5559 it were surrounded with a NE_EXPR. */
5568 {
5572 }
5575 {
5579 }
5590 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5593 {
5596 {
5601 }
5604 {
5610 }
5611 }
5616 /* If the RHS can be evaluated unconditionally and its operands are
5617 simple, it wins to evaluate the RHS unconditionally on machines
5618 with expensive branches. In this case, this isn't a comparison
5619 that can be merged. */
5626 {
5627 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5638 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5648 }
5650 /* See if the comparisons can be merged. Then get all the parameters for
5651 each side. */
5676 /* It must be true that the inner operation on the lhs of each
5677 comparison must be the same if we are to be able to do anything.
5678 Then see if we have constants. If not, the same must be true for
5679 the rhs's. */
5688 {
5691 }
5696 else
5699 /* If either comparison code is not correct for our logical operation,
5700 fail. However, we can convert a one-bit comparison against zero into
5701 the opposite comparison against that bit being set in the field. */
5705 {
5707 {
5708 /* Make the left operand unsigned, since we are only interested
5709 in the value of one bit. Otherwise we are doing the wrong
5710 thing below. */
5713 }
5714 else
5716 }
5718 /* This is analogous to the code for l_const above. */
5720 {
5722 {
5725 }
5726 else
5728 }
5730 /* See if we can find a mode that contains both fields being compared on
5731 the left. If we can't, fail. Otherwise, update all constants and masks
5732 to be relative to a field of that size. */
5737 volatilep);
5747 {
5750 }
5758 {
5765 {
5769 }
5770 }
5772 {
5779 {
5783 }
5784 }
5786 /* If the right sides are not constant, do the same for it. Also,
5787 disallow this optimization if a size or signedness mismatch occurs
5788 between the left and right sides. */
5790 {
5793 /* Make sure the two fields on the right
5794 correspond to the left without being swapped. */
5802 volatilep);
5812 {
5815 }
5824 /* Make a mask that corresponds to both fields being compared.
5825 Do this for both items being compared. If the operands are the
5826 same size and the bits being compared are in the same position
5827 then we can do this by masking both and comparing the masked
5828 results. */
5832 {
5844 }
5846 /* There is still another way we can do something: If both pairs of
5847 fields being compared are adjacent, we may be able to make a wider
5848 field containing them both.
5850 Note that we still must mask the lhs/rhs expressions. Furthermore,
5851 the mask must be shifted to account for the shift done by
5852 make_bit_field_ref. */
5857 {
5858 tree type;
5874 /* Convert to the smaller type before masking out unwanted bits. */
5877 {
5879 {
5883 }
5885 {
5889 }
5890 }
5899 }
5902 }
5904 /* Handle the case of comparisons with constants. If there is something in
5905 common between the masks, those bits of the constants must be the same.
5906 If not, the condition is always false. Test for this to avoid generating
5907 incorrect code below. */
5912 {
5914 {
5917 }
5918 else
5919 {
5922 }
5923 }
5925 /* Construct the expression we will return. First get the component
5926 reference we will make. Unless the mask is all ones the width of
5927 that field, perform the mask operation. Then compare with the
5928 merged constant. */
5938 }
5939 \f
5940 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5941 constant. */
5943 static tree
5946 {
5949 tree comp_const;
5950 tree minmax_const;
5952 tree inner;
5963 /* If something does not permit us to optimize, return the original tree. */
5971 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5972 and GT_EXPR, doing the rest with recursive calls using logical
5973 simplifications. */
5975 {
5977 {
5978 tree tem
5985 }
5988 return
5990 optimize_minmax_comparison
5992 optimize_minmax_comparison
5997 /* MAX (X, 0) == 0 -> X <= 0 */
6001 /* MAX (X, 0) == 5 -> X == 5 */
6005 /* MAX (X, 0) == -1 -> false */
6009 /* MIN (X, 0) == 0 -> X >= 0 */
6013 /* MIN (X, 0) == 5 -> false */
6016 else
6017 /* MIN (X, 0) == -1 -> X == -1 */
6022 /* MAX (X, 0) > 0 -> X > 0
6023 MAX (X, 0) > 5 -> X > 5 */
6027 /* MAX (X, 0) > -1 -> true */
6031 /* MIN (X, 0) > 0 -> false
6032 MIN (X, 0) > 5 -> false */
6035 else
6036 /* MIN (X, 0) > -1 -> X > -1 */
6041 }
6042 }
6043 \f
6044 /* T is an integer expression that is being multiplied, divided, or taken a
6045 modulus (CODE says which and what kind of divide or modulus) by a
6046 constant C. See if we can eliminate that operation by folding it with
6047 other operations already in T. WIDE_TYPE, if non-null, is a type that
6048 should be used for the computation if wider than our type.
6050 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6051 (X * 2) + (Y * 4). We must, however, be assured that either the original
6052 expression would not overflow or that overflow is undefined for the type
6053 in the language in question.
6055 If we return a non-null expression, it is an equivalent form of the
6056 original computation, but need not be in the original type.
6058 We set *STRICT_OVERFLOW_P to true if the return values depends on
6059 signed overflow being undefined. Otherwise we do not change
6060 *STRICT_OVERFLOW_P. */
6062 static tree
6065 {
6066 /* To avoid exponential search depth, refuse to allow recursion past
6067 three levels. Beyond that (1) it's highly unlikely that we'll find
6068 something interesting and (2) we've probably processed it before
6069 when we built the inner expression. */
6072 tree ret;
6077 depth++;
6079 depth--;
6082 }
6084 static tree
6087 {
6098 /* Don't deal with constants of zero here; they confuse the code below. */
6108 /* Note that we need not handle conditional operations here since fold
6109 already handles those cases. So just do arithmetic here. */
6111 {
6113 /* For a constant, we can always simplify if we are a multiply
6114 or (for divide and modulus) if it is a multiple of our constant. */
6117 {
6120 /* If the multiplication overflowed, we lost information on it.
6121 See PR68142 and PR69845. */
6125 }
6129 /* If op0 is an expression ... */
6135 /* ... and has wrapping overflow, and its type is smaller
6136 than ctype, then we cannot pass through as widening. */
6141 /* ... or this is a truncation (t is narrower than op0),
6142 then we cannot pass through this narrowing. */
6145 /* ... or signedness changes for division or modulus,
6146 then we cannot pass through this conversion. */
6150 /* ... or has undefined overflow while the converted to
6151 type has not, we cannot do the operation in the inner type
6152 as that would introduce undefined overflow. */
6158 /* Pass the constant down and see if we can make a simplification. If
6159 we can, replace this expression with the inner simplification for
6160 possible later conversion to our or some other type. */
6165 code == MULT_EXPR
6167 strict_overflow_p))))
6172 /* If widening the type changes it from signed to unsigned, then we
6173 must avoid building ABS_EXPR itself as unsigned. */
6175 {
6179 {
6182 }
6184 }
6185 /* If the constant is negative, we cannot simplify this. */
6188 /* FALLTHROUGH */
6190 /* For division and modulus, type can't be unsigned, as e.g.
6191 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6192 For signed types, even with wrapping overflow, this is fine. */
6201 /* If widening the type changes the signedness, then we can't perform
6202 this optimization as that changes the result. */
6206 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6212 {
6219 }
6223 /* If the second operand is constant, this is a multiplication
6224 or floor division, by a power of two, so we can treat it that
6225 way unless the multiplier or divisor overflows. Signed
6226 left-shift overflow is implementation-defined rather than
6227 undefined in C90, so do not convert signed left shift into
6228 multiplication. */
6231 /* const_binop may not detect overflow correctly,
6232 so check for it explicitly here. */
6236 size_one_node,
6237 op1)))
6241 ctype,
6243 t1),
6248 /* See if we can eliminate the operation on both sides. If we can, we
6249 can return a new PLUS or MINUS. If we can't, the only remaining
6250 cases where we can do anything are if the second operand is a
6251 constant. */
6257 /* If not multiplication, we can only do this if both operands
6258 are divisible by c. */
6261 {
6266 }
6268 /* If this was a subtraction, negate OP1 and set it to be an addition.
6269 This simplifies the logic below. */
6271 {
6273 /* If OP1 was not easily negatable, the constant may be OP0. */
6275 {
6278 }
6279 }
6284 /* If either OP1 or C are negative, this optimization is not safe for
6285 some of the division and remainder types while for others we need
6286 to change the code. */
6288 {
6296 }
6298 /* If it's a multiply or a division/modulus operation of a multiple
6299 of our constant, do the operation and verify it doesn't overflow. */
6302 {
6305 /* We allow the constant to overflow with wrapping semantics. */
6309 }
6310 else
6313 /* If we have an unsigned type, we cannot widen the operation since it
6314 will change the result if the original computation overflowed. */
6318 /* If we were able to eliminate our operation from the first side,
6319 apply our operation to the second side and reform the PLUS. */
6323 /* The last case is if we are a multiply. In that case, we can
6324 apply the distributive law to commute the multiply and addition
6325 if the multiplication of the constants doesn't overflow
6326 and overflow is defined. With undefined overflow
6327 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6333 op1);
6338 /* We have a special case here if we are doing something like
6339 (C * 8) % 4 since we know that's zero. */
6342 /* If the multiplication can overflow we cannot optimize this. */
6346 {
6349 }
6351 /* ... fall through ... */
6355 /* If we can extract our operation from the LHS, do so and return a
6356 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6357 do something only if the second operand is a constant. */
6371 /* If these are the same operation types, we can associate them
6372 assuming no overflow. */
6374 {
6391 }
6393 /* If these operations "cancel" each other, we have the main
6394 optimizations of this pass, which occur when either constant is a
6395 multiple of the other, in which case we replace this with either an
6396 operation or CODE or TCODE.
6398 If we have an unsigned type, we cannot do this since it will change
6399 the result if the original computation overflowed. */
6406 {
6408 {
6415 }
6417 {
6424 }
6425 }
6430 }
6433 }
6434 \f
6435 /* Return a node which has the indicated constant VALUE (either 0 or
6436 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6437 and is of the indicated TYPE. */
6439 tree
6441 {
6450 else
6452 }
6455 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6456 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6457 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6458 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6459 COND is the first argument to CODE; otherwise (as in the example
6460 given here), it is the second argument. TYPE is the type of the
6461 original expression. Return NULL_TREE if no simplification is
6462 possible. */
6464 static tree
6469 {
6479 {
6483 /* If this operand throws an expression, then it does not make
6484 sense to try to perform a logical or arithmetic operation
6485 involving it. */
6490 }
6493 {
6498 }
6499 else
6500 /* Detect the case of mixing vector and scalar types - bail out. */
6506 /* This transformation is only worthwhile if we don't have to wrap ARG
6507 in a SAVE_EXPR and the operation can be simplified without recursing
6508 on at least one of the branches once its pushed inside the COND_EXPR. */
6517 {
6521 else
6523 }
6525 {
6529 else
6531 }
6533 /* Check that we have simplified at least one of the branches. */
6538 }
6540 \f
6541 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6543 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6544 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6545 ADDEND is the same as X.
6547 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6548 and finite. The problematic cases are when X is zero, and its mode
6549 has signed zeros. In the case of rounding towards -infinity,
6550 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6551 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6553 bool
6555 {
6559 /* Don't allow the fold with -fsignaling-nans. */
6563 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6567 /* In a vector or complex, we would need to check the sign of all zeros. */
6571 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6575 /* The mode has signed zeros, and we have to honor their sign.
6576 In this situation, there is only one case we can return true for.
6577 X - 0 is the same as X unless rounding towards -infinity is
6578 supported. */
6580 }
6582 /* Subroutine of fold() that optimizes comparisons of a division by
6583 a nonzero integer constant against an integer constant, i.e.
6584 X/C1 op C2.
6586 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6587 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6588 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6590 The function returns the constant folded tree if a simplification
6591 can be made, and NULL_TREE otherwise. */
6593 static tree
6596 {
6604 /* We have to do this the hard way to detect unsigned overflow.
6605 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6611 {
6616 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6620 }
6622 {
6626 {
6645 }
6646 }
6647 else
6648 {
6649 /* A negative divisor reverses the relational operators. */
6655 {
6674 }
6675 }
6678 {
6699 {
6702 }
6707 {
6710 }
6715 {
6718 }
6723 {
6726 }
6731 }
6734 }
6737 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6738 equality/inequality test, then return a simplified form of the test
6739 using a sign testing. Otherwise return NULL. TYPE is the desired
6740 result type. */
6742 static tree
6745 tree result_type)
6746 {
6747 /* If this is testing a single bit, we can optimize the test. */
6751 {
6752 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6753 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6757 /* This is only a win if casting to a signed type is cheap,
6758 i.e. when arg00's type is not a partial mode. */
6761 {
6764 result_type,
6767 }
6768 }
6771 }
6773 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6774 equality/inequality test, then return a simplified form of
6775 the test using shifts and logical operations. Otherwise return
6776 NULL. TYPE is the desired result type. */
6778 tree
6781 {
6782 /* If this is testing a single bit, we can optimize the test. */
6786 {
6795 /* First, see if we can fold the single bit test into a sign-bit
6796 test. */
6798 result_type);
6802 /* Otherwise we have (A & C) != 0 where C is a single bit,
6803 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6804 Similarly for (A & C) == 0. */
6806 /* If INNER is a right shift of a constant and it plus BITNUM does
6807 not overflow, adjust BITNUM and INNER. */
6813 {
6816 }
6818 /* If we are going to be able to omit the AND below, we must do our
6819 operations as unsigned. If we must use the AND, we have a choice.
6820 Normally unsigned is faster, but for some machines signed is. */
6838 /* Put the AND last so it can combine with more things. */
6841 /* Make sure to return the proper type. */
6845 }
6847 }
6849 /* Check whether we are allowed to reorder operands arg0 and arg1,
6850 such that the evaluation of arg1 occurs before arg0. */
6852 static bool
6854 {
6861 }
6863 /* Test whether it is preferable two swap two operands, ARG0 and
6864 ARG1, for example because ARG0 is an integer constant and ARG1
6865 isn't. If REORDER is true, only recommend swapping if we can
6866 evaluate the operands in reverse order. */
6868 bool
6870 {
6888 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6889 for commutative and comparison operators. Ensuring a canonical
6890 form allows the optimizers to find additional redundancies without
6891 having to explicitly check for both orderings. */
6897 /* Put SSA_NAMEs last. */
6903 /* Put variables last. */
6910 }
6913 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6914 means A >= Y && A != MAX, but in this case we know that
6915 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6917 static tree
6919 {
6926 else
6935 {
6938 }
6940 {
6943 }
6944 else
6951 {
6952 /* Convert the pointer types into integer before taking the difference. */
6956 }
6957 else
6964 }
6966 /* Fold a sum or difference of at least one multiplication.
6967 Returns the folded tree or NULL if no simplification could be made. */
6969 static tree
6972 {
6976 /* (A * C) +- (B * C) -> (A+-B) * C.
6977 (A * C) +- A -> A * (C+-1).
6978 We are most concerned about the case where C is a constant,
6979 but other combinations show up during loop reduction. Since
6980 it is not difficult, try all four possibilities. */
6983 {
6986 }
6988 {
6991 }
6992 else
6993 {
6994 /* We cannot generate constant 1 for fract. */
6999 }
7001 {
7004 }
7006 {
7008 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7009 the purpose of this canonicalization. */
7013 {
7016 }
7017 else
7019 }
7020 else
7021 {
7022 /* We cannot generate constant 1 for fract. */
7027 }
7039 /* No identical multiplicands; see if we can find a common
7040 power-of-two factor in non-power-of-two multiplies. This
7041 can help in multi-dimensional array access. */
7044 {
7047 tree maybe_same;
7051 /* Move min of absolute values to int11. */
7053 {
7058 }
7059 else
7063 /* The remainder should not be a constant, otherwise we
7064 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7065 increased the number of multiplications necessary. */
7067 {
7075 }
7076 }
7086 }
7088 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7089 specified by EXPR into the buffer PTR of length LEN bytes.
7090 Return the number of bytes placed in the buffer, or zero
7091 upon failure. */
7093 static int
7095 {
7109 {
7111 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7112 number of bytes. */
7116 {
7123 else
7125 }
7126 else
7131 }
7133 }
7136 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7137 specified by EXPR into the buffer PTR of length LEN bytes.
7138 Return the number of bytes placed in the buffer, or zero
7139 upon failure. */
7141 static int
7143 {
7147 FIXED_VALUE_TYPE value;
7163 }
7166 /* Subroutine of native_encode_expr. Encode the REAL_CST
7167 specified by EXPR into the buffer PTR of length LEN bytes.
7168 Return the number of bytes placed in the buffer, or zero
7169 upon failure. */
7171 static int
7173 {
7179 /* There are always 32 bits in each long, no matter the size of
7180 the hosts long. We handle floating point representations with
7181 up to 192 bits. */
7195 {
7200 {
7207 else
7209 }
7210 else
7216 }
7218 }
7220 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7221 specified by EXPR into the buffer PTR of length LEN bytes.
7222 Return the number of bytes placed in the buffer, or zero
7223 upon failure. */
7225 static int
7227 {
7229 tree part;
7244 }
7247 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7248 specified by EXPR into the buffer PTR of length LEN bytes.
7249 Return the number of bytes placed in the buffer, or zero
7250 upon failure. */
7252 static int
7254 {
7264 {
7266 {
7269 }
7280 }
7282 }
7285 /* Subroutine of native_encode_expr. Encode the STRING_CST
7286 specified by EXPR into the buffer PTR of length LEN bytes.
7287 Return the number of bytes placed in the buffer, or zero
7288 upon failure. */
7290 static int
7292 {
7294 HOST_WIDE_INT total_bytes;
7308 {
7311 {
7314 }
7317 }
7318 else
7321 }
7324 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7325 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7326 buffer PTR of length LEN bytes. If OFF is not -1 then start
7327 the encoding at byte offset OFF and encode at most LEN bytes.
7328 Return the number of bytes placed in the buffer, or zero upon failure. */
7330 int
7332 {
7333 /* We don't support starting at negative offset and -1 is special. */
7338 {
7359 }
7360 }
7363 /* Subroutine of native_interpret_expr. Interpret the contents of
7364 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7365 If the buffer cannot be interpreted, return NULL_TREE. */
7367 static tree
7369 {
7379 }
7382 /* Subroutine of native_interpret_expr. Interpret the contents of
7383 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7384 If the buffer cannot be interpreted, return NULL_TREE. */
7386 static tree
7388 {
7390 double_int result;
7391 FIXED_VALUE_TYPE fixed_value;
7401 }
7404 /* Subroutine of native_interpret_expr. Interpret the contents of
7405 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7406 If the buffer cannot be interpreted, return NULL_TREE. */
7408 static tree
7410 {
7414 /* There are always 32 bits in each long, no matter the size of
7415 the hosts long. We handle floating point representations with
7416 up to 192 bits. */
7417 REAL_VALUE_TYPE r;
7428 {
7429 /* Both OFFSET and BYTE index within a long;
7430 bitpos indexes the whole float. */
7433 {
7440 else
7442 }
7443 else
7444 {
7447 {
7448 /* Reverse bytes within each long, or within the entire float
7449 if it's smaller than a long (for HFmode). */
7452 }
7453 }
7457 }
7461 }
7464 /* Subroutine of native_interpret_expr. Interpret the contents of
7465 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7466 If the buffer cannot be interpreted, return NULL_TREE. */
7468 static tree
7470 {
7485 }
7488 /* Subroutine of native_interpret_expr. Interpret the contents of
7489 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7490 If the buffer cannot be interpreted, return NULL_TREE. */
7492 static tree
7494 {
7507 {
7512 }
7514 }
7517 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7518 the buffer PTR of length LEN as a constant of type TYPE. For
7519 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7520 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7521 return NULL_TREE. */
7523 tree
7525 {
7527 {
7549 }
7550 }
7552 /* Returns true if we can interpret the contents of a native encoding
7553 as TYPE. */
7555 static bool
7557 {
7559 {
7572 }
7573 }
7575 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7576 TYPE at compile-time. If we're unable to perform the conversion
7577 return NULL_TREE. */
7579 static tree
7581 {
7582 /* We support up to 512-bit values (for V8DFmode). */
7586 /* Check that the host and target are sane. */
7595 }
7597 /* Build an expression for the address of T. Folds away INDIRECT_REF
7598 to avoid confusing the gimplify process. */
7600 tree
7602 {
7603 /* The size of the object is not relevant when talking about its address. */
7608 {
7613 }
7623 {
7628 }
7629 else
7633 }
7635 /* Build an expression for the address of T. */
7637 tree
7639 {
7643 }
7645 /* Fold a unary expression of code CODE and type TYPE with operand
7646 OP0. Return the folded expression if folding is successful.
7647 Otherwise, return NULL_TREE. */
7649 tree
7651 {
7652 tree tem;
7653 tree arg0;
7661 {
7664 {
7665 /* Don't use STRIP_NOPS, because signedness of argument type
7666 matters. */
7668 }
7669 else
7670 {
7671 /* Strip any conversions that don't change the mode. This
7672 is safe for every expression, except for a comparison
7673 expression because its signedness is derived from its
7674 operands.
7676 Note that this is done as an internal manipulation within
7677 the constant folder, in order to find the simplest
7678 representation of the arguments so that their form can be
7679 studied. In any cases, the appropriate type conversions
7680 should be put back in the tree that will get out of the
7681 constant folder. */
7683 }
7686 {
7689 {
7693 }
7694 }
7695 }
7702 {
7709 {
7723 /* If this was a conversion, and all we did was to move into
7724 inside the COND_EXPR, bring it back out. But leave it if
7725 it is a conversion from integer to integer and the
7726 result precision is no wider than a word since such a
7727 conversion is cheap and may be optimized away by combine,
7728 while it couldn't if it were outside the COND_EXPR. Then return
7729 so we don't get into an infinite recursion loop taking the
7730 conversion out and then back in. */
7742 && (INTEGRAL_TYPE_P
7755 }
7756 }
7759 {
7765 CASE_CONVERT:
7769 {
7770 /* If we have (type) (a CMP b) and type is an integral type, return
7771 new expression involving the new type. Canonicalize
7772 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7773 non-integral type.
7774 Do not fold the result as that would not simplify further, also
7775 folding again results in recursions. */
7785 }
7787 /* Handle (T *)&A.B.C for A being of type T and B and C
7788 living at offset zero. This occurs frequently in
7789 C++ upcasting and then accessing the base. */
7793 {
7795 tree offset;
7796 machine_mode mode;
7798 tree base
7802 /* If the reference was to a (constant) zero offset, we can use
7803 the address of the base if it has the same base type
7804 as the result type and the pointer type is unqualified. */
7811 }
7815 /* Detect assigning a bitfield. */
7817 && DECL_BIT_FIELD
7819 {
7820 /* Don't leave an assignment inside a conversion
7821 unless assigning a bitfield. */
7823 /* First do the assignment, then return converted constant. */
7828 }
7830 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7831 constants (if x has signed type, the sign bit cannot be set
7832 in c). This folds extension into the BIT_AND_EXPR.
7833 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7834 very likely don't have maximal range for their precision and this
7835 transformation effectively doesn't preserve non-maximal ranges. */
7839 {
7850 <= HOST_BITS_PER_WIDE_INT
7852 {
7856 cst &= HOST_WIDE_INT_M1U
7860 && !flag_syntax_only
7863 {
7867 }
7868 }
7870 {
7875 }
7876 }
7878 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7879 cast (T1)X will fold away. We assume that this happens when X itself
7880 is a cast. */
7884 {
7888 return fold_build_pointer_plus_loc
7890 }
7892 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7893 of the same precision, and X is an integer type not narrower than
7894 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7900 {
7906 }
7908 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7909 type of X and Y (integer types only). */
7914 {
7915 /* Be careful not to introduce new overflows. */
7916 tree mult_type;
7919 else
7923 {
7930 }
7931 }
7937 {
7942 }
7953 /* Convert fabs((double)float) into (double)fabsf(float). */
7956 {
7962 targ0));
7963 }
7967 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7986 /* Note that the operand of this must be an int
7987 and its values must be 0 or 1.
7988 ("true" is a fixed value perhaps depending on the language,
7989 but we don't handle values other than 1 correctly yet.) */
7996 /* Fold *&X to X if X is an lvalue. */
7998 {
8005 }
8011 }
8014 /* If the operation was a conversion do _not_ mark a resulting constant
8015 with TREE_OVERFLOW if the original constant was not. These conversions
8016 have implementation defined behavior and retaining the TREE_OVERFLOW
8017 flag here would confuse later passes such as VRP. */
8018 tree
8021 {
8030 }
8032 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8033 operands OP0 and OP1. LOC is the location of the resulting expression.
8034 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8035 Return the folded expression if folding is successful. Otherwise,
8036 return NULL_TREE. */
8037 static tree
8040 {
8041 tree tem;
8043 /* We only do these simplifications if we are optimizing. */
8047 /* Check for things like (A || B) && (A || C). We can convert this
8048 to A || (B && C). Note that either operator can be any of the four
8049 truth and/or operations and the transformation will still be
8050 valid. Also note that we only care about order for the
8051 ANDIF and ORIF operators. If B contains side effects, this
8052 might change the truth-value of A. */
8059 {
8079 /* This case if tricky because we must either have commutative
8080 operators or else A10 must not have side-effects. */
8086 a01);
8087 }
8089 /* See if we can build a range comparison. */
8095 {
8099 }
8103 {
8107 }
8109 /* Check for the possibility of merging component references. If our
8110 lhs is another similar operation, try to merge its rhs with our
8111 rhs. Then try to merge our lhs and rhs. */
8125 {
8132 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8133 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8134 We don't want to pack more than two leafs to a non-IF AND/OR
8135 expression.
8136 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8137 equal to IF-CODE, then we don't want to add right-hand operand.
8138 If the inner right-hand side of left-hand operand has
8139 side-effects, or isn't simple, then we can't add to it,
8140 as otherwise we might destroy if-sequence. */
8143 /* Needed for sequence points to handle trappings, and
8144 side-effects. */
8146 {
8148 arg1);
8150 tem);
8151 }
8152 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8153 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8156 /* Needed for sequence points to handle trappings, and
8157 side-effects. */
8159 {
8164 }
8165 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8166 into (A OR B).
8167 For sequence point consistancy, we need to check for trapping,
8168 and side-effects. */
8172 }
8175 }
8177 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8178 by changing CODE to reduce the magnitude of constants involved in
8179 ARG0 of the comparison.
8180 Returns a canonicalized comparison tree if a simplification was
8181 possible, otherwise returns NULL_TREE.
8182 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8183 valid if signed overflow is undefined. */
8185 static tree
8189 {
8194 /* Match A +- CST code arg1. We can change this only if overflow
8195 is undefined. */
8198 /* In principle pointers also have undefined overflow behavior,
8199 but that causes problems elsewhere. */
8206 /* Identify the constant in arg0 and its sign. */
8210 /* Overflowed constants and zero will cause problems. */
8215 /* See if we can reduce the magnitude of the constant in
8216 arg0 by changing the comparison code. */
8217 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8221 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8225 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8229 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8233 else
8237 /* Now build the constant reduced in magnitude. But not if that
8238 would produce one outside of its types range. */
8254 }
8256 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8257 overflow further. Try to decrease the magnitude of constants involved
8258 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8259 and put sole constants at the second argument position.
8260 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8262 static tree
8265 {
8266 tree t;
8271 /* Try canonicalization by simplifying arg0. */
8276 {
8280 }
8282 /* Try canonicalization by simplifying arg1 using the swapped
8283 comparison. */
8291 }
8293 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8294 space. This is used to avoid issuing overflow warnings for
8295 expressions like &p->x which can not wrap. */
8297 static bool
8299 {
8306 wide_int wi_offset;
8312 else
8328 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8329 array. */
8331 {
8332 HOST_WIDE_INT base_size;
8337 }
8340 }
8342 /* Return a positive integer when the symbol DECL is known to have
8343 a nonzero address, zero when it's known not to (e.g., it's a weak
8344 symbol), and a negative integer when the symbol is not yet in the
8345 symbol table and so whether or not its address is zero is unknown. */
8346 static int
8348 {
8354 }
8356 /* Subroutine of fold_binary. This routine performs all of the
8357 transformations that are common to the equality/inequality
8358 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8359 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8360 fold_binary should call fold_binary. Fold a comparison with
8361 tree code CODE and type TYPE with operands OP0 and OP1. Return
8362 the folded comparison or NULL_TREE. */
8364 static tree
8367 {
8377 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8379 && (equality_code
8386 {
8387 const enum tree_code
8394 /* If the constant operation overflowed this can be
8395 simplified as a comparison against INT_MAX/INT_MIN. */
8398 {
8402 /* Get the sign of the constant on the lhs if the
8403 operation were VARIABLE + CONST1. */
8407 /* The sign of the constant determines if we overflowed
8408 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8409 Canonicalize to the INT_MIN overflow by swapping the comparison
8410 if necessary. */
8414 /* We now can look at the canonicalized case
8415 VARIABLE + 1 CODE2 INT_MIN
8416 and decide on the result. */
8418 {
8422 return
8428 return
8433 }
8434 }
8435 else
8436 {
8439 "when changing X +- C1 cmp C2 to "
8441 WARN_STRICT_OVERFLOW_COMPARISON);
8443 }
8444 }
8446 /* For comparisons of pointers we can decompose it to a compile time
8447 comparison of the base objects and the offsets into the object.
8448 This requires at least one operand being an ADDR_EXPR or a
8449 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8455 {
8458 machine_mode mode;
8462 /* Get base and offset for the access. Strip ADDR_EXPR for
8463 get_inner_reference, but put it back by stripping INDIRECT_REF
8464 off the base object if possible. indirect_baseN will be true
8465 if baseN is not an address but refers to the object itself. */
8468 {
8469 base0
8475 else
8477 }
8479 {
8483 {
8484 base0
8491 else
8493 }
8496 else
8500 {
8506 {
8509 }
8510 }
8511 }
8515 {
8516 base1
8522 else
8524 }
8526 {
8530 {
8531 base1
8538 else
8540 }
8543 else
8547 {
8553 {
8556 }
8557 }
8558 }
8560 /* If we have equivalent bases we might be able to simplify. */
8564 {
8565 /* We can fold this expression to a constant if the non-constant
8566 offset parts are equal. */
8575 {
8581 "occur when comparing P +- C1 with "
8583 WARN_STRICT_OVERFLOW_CONDITIONAL);
8586 {
8600 }
8601 }
8602 /* We can simplify the comparison to a comparison of the variable
8603 offset parts if the constant offset parts are equal.
8604 Be careful to use signed sizetype here because otherwise we
8605 mess with array offsets in the wrong way. This is possible
8606 because pointer arithmetic is restricted to retain within an
8607 object and overflow on pointer differences is undefined as of
8608 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8610 && (equality_code
8613 {
8614 /* By converting to signed sizetype we cover middle-end pointer
8615 arithmetic which operates on unsigned pointer types of size
8616 type size and ARRAY_REF offsets which are properly sign or
8617 zero extended from their type in case it is narrower than
8618 sizetype. */
8621 else
8625 else
8632 "occur when comparing P +- C1 with "
8634 WARN_STRICT_OVERFLOW_COMPARISON);
8637 }
8638 }
8639 /* For equal offsets we can simplify to a comparison of the
8640 base addresses. */
8642 && (indirect_base0
8644 && (indirect_base1
8649 {
8655 }
8656 /* Comparison between an ordinary (non-weak) symbol and a null
8657 pointer can be eliminated since such symbols must have a non
8658 null address. In C, relational expressions between pointers
8659 to objects and null pointers are undefined. The results
8660 below follow the C++ rules with the additional property that
8661 every object pointer compares greater than a null pointer.
8662 */
8665 /* Avoid folding references to struct members at offset 0 to
8666 prevent tests like '&ptr->firstmember == 0' from getting
8667 eliminated. When ptr is null, although the -> expression
8668 is strictly speaking invalid, GCC retains it as a matter
8669 of QoI. See PR c/44555. */
8671 /* The caller guarantees that when one of the arguments is
8672 constant (i.e., null in this case) it is second. */
8674 {
8676 {
8687 }
8688 }
8689 }
8691 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8692 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8693 the resulting offset is smaller in absolute value than the
8694 original one and has the same sign. */
8703 {
8708 tree cst;
8710 "occur when combining constants around "
8713 /* Put the constant on the side where it doesn't overflow and is
8714 of lower absolute value and of same sign than before. */
8721 {
8724 variable1,
8728 }
8736 {
8742 variable2);
8743 }
8744 }
8750 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8751 constant, we can simplify it. */
8756 {
8760 }
8762 /* If we are comparing an expression that just has comparisons
8763 of two integer values, arithmetic expressions of those comparisons,
8764 and constants, we can simplify it. There are only three cases
8765 to check: the two values can either be equal, the first can be
8766 greater, or the second can be greater. Fold the expression for
8767 those three values. Since each value must be 0 or 1, we have
8768 eight possibilities, each of which corresponds to the constant 0
8769 or 1 or one of the six possible comparisons.
8771 This handles common cases like (a > b) == 0 but also handles
8772 expressions like ((x > y) - (y > x)) > 0, which supposedly
8773 occur in macroized code. */
8776 {
8781 /* Don't handle degenerate cases here; they should already
8782 have been handled anyway. */
8791 {
8795 /* We can't just pass T to eval_subst in case cval1 or cval2
8796 was the same as ARG1. */
8798 tree high_result
8802 arg1);
8803 tree equal_result
8807 arg1);
8808 tree low_result
8812 arg1);
8814 /* All three of these results should be 0 or 1. Confirm they are.
8815 Then use those values to select the proper code to use. */
8820 {
8821 /* Make a 3-bit mask with the high-order bit being the
8822 value for `>', the next for '=', and the low for '<'. */
8826 {
8828 /* Always false. */
8849 /* Always true. */
8851 }
8854 {
8858 }
8860 }
8861 }
8862 }
8864 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8865 into a single range test. */
8873 {
8877 }
8880 }
8883 /* Subroutine of fold_binary. Optimize complex multiplications of the
8884 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8885 argument EXPR represents the expression "z" of type TYPE. */
8887 static tree
8889 {
8894 {
8897 }
8899 {
8902 }
8903 else
8904 {
8908 }
8917 }
8920 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8921 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8923 static bool
8925 {
8929 {
8932 }
8934 {
8940 else
8942 }
8943 else
8949 }
8951 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8952 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8953 NULL_TREE otherwise. */
8955 static tree
8957 {
8974 {
8978 }
8981 {
8987 }
8988 else
8990 }
8992 /* Try to fold a pointer difference of type TYPE two address expressions of
8993 array references AREF0 and AREF1 using location LOC. Return a
8994 simplified expression for the difference or NULL_TREE. */
8996 static tree
8999 {
9004 /* If the bases are array references as well, recurse. If the bases
9005 are pointer indirections compute the difference of the pointers.
9006 If the bases are equal, we are set. */
9009 && (base_offset
9013 && (base_offset
9019 {
9025 base_offset,
9028 }
9030 }
9032 /* If the real or vector real constant CST of type TYPE has an exact
9033 inverse, return it, else return NULL. */
9035 tree
9037 {
9038 REAL_VALUE_TYPE r;
9040 machine_mode mode;
9044 {
9060 {
9065 }
9071 }
9072 }
9074 /* Mask out the tz least significant bits of X of type TYPE where
9075 tz is the number of trailing zeroes in Y. */
9076 static wide_int
9078 {
9083 }
9085 /* Return true when T is an address and is known to be nonzero.
9086 For floating point we further ensure that T is not denormal.
9087 Similar logic is present in nonzero_address in rtlanal.h.
9089 If the return value is based on the assumption that signed overflow
9090 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9091 change *STRICT_OVERFLOW_P. */
9093 static bool
9095 {
9099 /* Doing something useful for floating point would need more work. */
9105 {
9108 strict_overflow_p);
9114 strict_overflow_p);
9122 }
9125 {
9128 strict_overflow_p);
9136 strict_overflow_p);
9151 strict_overflow_p);
9155 strict_overflow_p);
9158 {
9170 }
9174 }
9176 }
9178 /* Return true when T is an address and is known to be nonzero.
9179 Handle warnings about undefined signed overflow. */
9181 static bool
9183 {
9190 "determining that expression is always "
9192 WARN_STRICT_OVERFLOW_MISC);
9194 }
9196 /* Return true if T is known not to be equal to an integer W. */
9198 bool
9200 {
9202 value_range_type rtype;
9204 {
9213 {
9218 }
9223 /* If T has some known zero bits and W has any of those bits set,
9224 then T is known not to be equal to W. */
9232 }
9233 }
9235 /* Fold a binary expression of code CODE and type TYPE with operands
9236 OP0 and OP1. LOC is the location of the resulting expression.
9237 Return the folded expression if folding is successful. Otherwise,
9238 return NULL_TREE. */
9240 tree
9243 {
9258 /* Strip any conversions that don't change the mode. This is
9259 safe for every expression, except for a comparison expression
9260 because its signedness is derived from its operands. So, in
9261 the latter case, only strip conversions that don't change the
9262 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9263 preserved.
9265 Note that this is done as an internal manipulation within the
9266 constant folder, in order to find the simplest representation
9267 of the arguments so that their form can be studied. In any
9268 cases, the appropriate type conversions should be put back in
9269 the tree that will get out of the constant folder. */
9272 {
9275 }
9276 else
9277 {
9280 }
9282 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9283 constant but we can't do arithmetic on them. */
9285 {
9288 {
9292 }
9293 }
9295 /* If this is a commutative operation, and ARG0 is a constant, move it
9296 to ARG1 to reduce the number of tests below. */
9301 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9302 to ARG1 to reduce the number of tests below. */
9311 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9313 First check for cases where an arithmetic operation is applied to a
9314 compound, conditional, or comparison operation. Push the arithmetic
9315 operation inside the compound or conditional to see if any folding
9316 can then be done. Convert comparison to conditional for this purpose.
9317 The also optimizes non-constant cases that used to be done in
9318 expand_expr.
9320 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9321 one of the operands is a comparison and the other is a comparison, a
9322 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9323 code below would make the expression more complex. Change it to a
9324 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9325 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9338 {
9342 boolean_type_node,
9350 }
9354 {
9356 {
9361 tem);
9362 }
9365 {
9370 tem);
9371 }
9376 {
9382 }
9387 {
9393 }
9394 }
9397 {
9399 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9402 {
9408 }
9410 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9413 {
9414 tree base;
9415 HOST_WIDE_INT coffset;
9424 }
9429 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9435 arg1),
9437 arg0)));
9443 {
9444 /* X + (X / CST) * -CST is X % CST. */
9449 {
9458 cst0));
9459 }
9460 }
9462 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9463 one. Make sure the type is not saturating and has the signedness of
9464 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9465 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9472 {
9476 }
9479 {
9480 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9481 (plus (plus (mult) (mult)) (foo)) so that we can
9482 take advantage of the factoring cases below. */
9491 {
9497 else
9510 parg0),
9512 marg)),
9516 return
9522 parg1)));
9523 }
9524 }
9525 else
9526 {
9527 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9528 to __complex__ ( x, y ). This is not the same for SNaNs or
9529 if signed zeros are involved. */
9533 {
9540 {
9544 {
9550 }
9552 {
9558 }
9559 }
9560 }
9568 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9569 We associate floats only if the user has specified
9570 -fassociative-math. */
9574 {
9579 {
9580 tree tree0;
9583 }
9584 }
9585 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9586 We associate floats only if the user has specified
9587 -fassociative-math. */
9591 {
9596 {
9597 tree tree0;
9600 }
9601 }
9602 }
9604 bit_rotate:
9605 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9606 is a rotate of A by C1 bits. */
9607 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9608 is a rotate of A by B bits. */
9609 {
9611 tree rtype;
9620 /* Only create rotates in complete modes. Other cases are not
9621 expanded properly. */
9624 {
9638 {
9642 code0 == LSHIFT_EXPR
9646 }
9648 {
9656 element_precision
9660 return
9663 ? LROTATE_EXPR
9668 }
9670 {
9678 element_precision
9682 return fold_convert_loc
9685 ? LROTATE_EXPR
9689 }
9690 }
9691 }
9693 associate:
9694 /* In most languages, can't associate operations on floats through
9695 parentheses. Rather than remember where the parentheses were, we
9696 don't associate floats at all, unless the user has specified
9697 -fassociative-math.
9698 And, we need to make sure type is not saturating. */
9702 {
9708 /* Split both trees into variables, constants, and literals. Then
9709 associate each group together, the constants with literals,
9710 then the result with variables. This increases the chances of
9711 literals being recombined later and of generating relocatable
9712 expressions for the sum of a constant and literal. */
9718 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9722 /* With undefined overflow prefer doing association in a type
9723 which wraps on overflow, if that is one of the operand types. */
9726 {
9734 }
9736 /* With undefined overflow we can only associate constants with one
9737 variable, and constants whose association doesn't overflow. */
9740 {
9742 {
9748 {
9751 }
9758 {
9761 }
9767 /* The only case we can still associate with two variables
9768 is if they cancel out. */
9772 }
9773 }
9775 /* Only do something if we found more than two objects. Otherwise,
9776 nothing has changed and we risk infinite recursion. */
9782 {
9794 /* Preserve the MINUS_EXPR if the negative part of the literal is
9795 greater than the positive part. Otherwise, the multiplicative
9796 folding code (i.e extract_muldiv) may be fooled in case
9797 unsigned constants are subtracted, like in the following
9798 example: ((X*2 + 4) - 8U)/2. */
9800 {
9804 {
9808 }
9809 else
9810 {
9814 }
9815 }
9817 /* Don't introduce overflows through reassociation. */
9824 {
9826 return
9830 else
9831 {
9834 return
9838 }
9839 }
9842 return
9845 }
9846 }
9851 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9860 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9861 __complex__ ( x, -y ). This is not the same for SNaNs or if
9862 signed zeros are involved. */
9866 {
9873 {
9877 {
9879 arg1r ? arg1r
9884 }
9886 {
9890 arg1i ? arg1i
9893 }
9894 }
9895 }
9897 /* A - B -> A + (-B) if B is easily negatable. */
9901 /* Avoid this transformation if B is a positive REAL_CST. */
9909 /* Fold &a[i] - &a[j] to i-j. */
9914 {
9920 }
9923 && flag_unsafe_math_optimizations
9929 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9930 one. Make sure the type is not saturating and has the signedness of
9931 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9932 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9939 {
9943 }
9949 {
9950 /* Transform x * -C into -x * C if x is easily negatable. */
9960 /* (A + A) * C -> A * 2 * C */
9972 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9973 sign-changing only. */
9983 {
9986 "occur when simplifying "
9988 WARN_STRICT_OVERFLOW_MISC);
9990 }
9992 /* Optimize z * conj(z) for integer complex numbers. */
9999 }
10000 else
10001 {
10002 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10003 This is not the same for NaNs or if signed zeros are
10004 involved. */
10010 {
10013 return
10019 return
10024 }
10026 /* Optimize z * conj(z) for floating point complex numbers.
10027 Guarded by flag_unsafe_math_optimizations as non-finite
10028 imaginary components don't produce scalar results. */
10039 {
10041 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10043 && optimize
10045 {
10049 {
10052 }
10053 }
10054 }
10055 }
10059 /* Canonicalize (X & C1) | C2. */
10063 {
10068 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10076 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10081 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10082 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10083 mode which allows further optimizations. */
10088 {
10092 {
10095 }
10096 }
10103 c3)),
10104 arg1);
10105 }
10107 /* See if this can be simplified into a rotate first. If that
10108 is unsuccessful continue in the association code. */
10112 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10120 /* See if this can be simplified into a rotate first. If that
10121 is unsuccessful continue in the association code. */
10125 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10130 {
10131 tree tem2;
10138 }
10139 /* Fold ~X & 1 as (X & 1) == 0. */
10143 {
10144 tree tem2;
10151 }
10152 /* Fold !X & 1 as X == 0. */
10155 {
10159 }
10161 /* Fold (X ^ Y) & Y as ~X & Y. */
10164 {
10169 }
10170 /* Fold (X ^ Y) & X as ~Y & X. */
10174 {
10179 }
10180 /* Fold X & (X ^ Y) as X & ~Y. */
10183 {
10188 }
10189 /* Fold X & (Y ^ X) as ~Y & X. */
10193 {
10198 }
10200 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10201 multiple of 1 << CST. */
10203 {
10210 }
10212 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10213 bits from CST2. */
10217 {
10225 {
10226 /* Avoid the transform if arg1 is a mask of some
10227 mode which allows further optimizations. */
10234 }
10235 }
10237 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10238 ((A & N) + B) & M -> (A + B) & M
10239 Similarly if (N & M) == 0,
10240 ((A | N) + B) & M -> (A + B) & M
10241 and for - instead of + (or unary - instead of +)
10242 and/or ^ instead of |.
10243 If B is constant and (B & M) == 0, fold into A & M. */
10245 {
10254 {
10257 wide_int cst0;
10259 /* Now we know that arg0 is (C + D) or (C - D) or
10260 -C and arg1 (M) is == (1LL << cst) - 1.
10261 Store C into PMOP[0] and D into PMOP[1]. */
10265 {
10268 }
10275 {
10285 {
10288 }
10291 /* If C or D is of the form (A & N) where
10292 (N & M) == M, or of the form (A | N) or
10293 (A ^ N) where (N & M) == 0, replace it with A. */
10297 /* If C or D is a N where (N & M) == 0, it can be
10298 omitted (assumed 0). */
10306 }
10308 /* Only build anything new if we optimized one or both arguments
10309 above. */
10313 {
10316 {
10317 /* Perform the operations in a type that has defined
10318 overflow behavior. */
10324 }
10329 {
10337 else
10339 }
10342 else
10345 /* TEM is now the new binary +, - or unary - replacement. */
10349 }
10350 }
10351 }
10353 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10356 {
10361 return
10363 }
10368 /* Don't touch a floating-point divide by zero unless the mode
10369 of the constant can represent infinity. */
10375 /* (-A) / (-B) -> A / B */
10387 /* Fall through */
10390 /* Simplify A / (B << N) where A and B are positive and B is
10391 a power of 2, to A >> (N + log2(B)). */
10396 {
10399 {
10407 WARN_STRICT_OVERFLOW_MISC);
10413 }
10414 }
10416 /* Fall through */
10424 /* Convert -A / -B to A / B when the type is signed and overflow is
10425 undefined. */
10429 {
10432 "when distributing negation across "
10434 WARN_STRICT_OVERFLOW_MISC);
10439 }
10443 {
10446 "when distributing negation across "
10448 WARN_STRICT_OVERFLOW_MISC);
10453 }
10455 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10456 operation, EXACT_DIV_EXPR.
10458 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10459 At one time others generated faster code, it's not clear if they do
10460 after the last round to changes to the DIV code in expmed.c. */
10471 {
10475 WARN_STRICT_OVERFLOW_MISC);
10477 }
10489 {
10493 WARN_STRICT_OVERFLOW_MISC);
10495 }
10503 /* Since negative shift count is not well-defined,
10504 don't try to compute it in the compiler. */
10510 /* If we have a rotate of a bit operation with the rotate count and
10511 the second operand of the bit operation both constant,
10512 permute the two operations. */
10524 /* Two consecutive rotates adding up to the some integer
10525 multiple of the precision of the type can be ignored. */
10540 /* Note that the operands of this must be ints
10541 and their values must be 0 or 1.
10542 ("true" is a fixed value perhaps depending on the language.) */
10543 /* If first arg is constant zero, return it. */
10547 /* If either arg is constant true, drop it. */
10551 /* Preserve sequence points. */
10554 /* If second arg is constant zero, result is zero, but first arg
10555 must be evaluated. */
10558 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10559 case will be handled here. */
10563 /* !X && X is always false. */
10567 /* X && !X is always false. */
10572 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10573 means A >= Y && A != MAX, but in this case we know that
10574 A < X <= MAX. */
10578 {
10586 }
10595 /* Note that the operands of this must be ints
10596 and their values must be 0 or true.
10597 ("true" is a fixed value perhaps depending on the language.) */
10598 /* If first arg is constant true, return it. */
10602 /* If either arg is constant zero, drop it. */
10606 /* Preserve sequence points. */
10609 /* If second arg is constant true, result is true, but we must
10610 evaluate first arg. */
10613 /* Likewise for first arg, but note this only occurs here for
10614 TRUTH_OR_EXPR. */
10618 /* !X || X is always true. */
10622 /* X || !X is always true. */
10627 /* (X && !Y) || (!X && Y) is X ^ Y */
10630 {
10647 }
10656 /* If the second arg is constant zero, drop it. */
10659 /* If the second arg is constant true, this is a logical inversion. */
10661 {
10664 }
10665 /* Identical arguments cancel to zero. */
10669 /* !X ^ X is always true. */
10674 /* X ^ !X is always true. */
10690 /* bool_var != 1 becomes !bool_var. */
10697 /* bool_var == 0 becomes !bool_var. */
10704 /* !exp != 0 becomes !exp */
10709 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10718 {
10724 }
10726 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10735 {
10741 }
10743 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10751 code == NE_EXPR
10755 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10763 code == NE_EXPR
10767 /* If this is an EQ or NE comparison with zero and ARG0 is
10768 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10769 two operations, but the latter can be done in one less insn
10770 on machines that have only two-operand insns or on which a
10771 constant cannot be the first operand. */
10774 {
10779 {
10786 arg1);
10787 }
10790 {
10797 arg1);
10798 }
10799 }
10801 /* If this is an NE or EQ comparison of zero against the result of a
10802 signed MOD operation whose second operand is a power of 2, make
10803 the MOD operation unsigned since it is simpler and equivalent. */
10811 {
10821 }
10823 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10824 C1 is a valid shift constant, and C2 is a power of two, i.e.
10825 a single bit. */
10829 == INTEGER_CST
10832 {
10837 /* Check for a valid shift count. */
10839 {
10843 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10844 can be rewritten as (X & (C2 << C1)) != 0. */
10846 {
10851 }
10852 /* Otherwise, for signed (arithmetic) shifts,
10853 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10854 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10858 /* Otherwise, of unsigned (logical) shifts,
10859 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10860 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10861 else
10865 arg000);
10866 }
10867 }
10869 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10870 Similarly for NE_EXPR. */
10874 {
10878 tree dandnotc
10881 notc);
10885 }
10887 /* If this is a comparison of a field, we may be able to simplify it. */
10890 /* Handle the constant case even without -O
10891 to make sure the warnings are given. */
10893 {
10897 }
10899 /* Optimize comparisons of strlen vs zero to a compare of the
10900 first character of the string vs zero. To wit,
10901 strlen(ptr) == 0 => *ptr == 0
10902 strlen(ptr) != 0 => *ptr != 0
10903 Other cases should reduce to one of these two (or a constant)
10904 due to the return value of strlen being unsigned. */
10907 {
10915 {
10920 }
10921 }
10923 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10924 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10928 {
10933 {
10935 {
10938 }
10941 }
10942 }
10944 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10945 (X & C) == 0 when C is a single bit. */
10950 {
10957 arg1));
10958 }
10960 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10961 constant C is a power of two, i.e. a single bit. */
10968 {
10972 }
10974 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10975 when is C is a power of two, i.e. a single bit. */
10982 {
10988 }
10992 {
10995 }
10997 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11000 {
11013 arg01),
11022 arg01),
11031 arg00),
11040 arg00),
11042 }
11046 {
11053 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11054 operand_equal_p guarantees no side-effects so we don't need
11055 to use omit_one_operand on Z. */
11059 arg10));
11063 arg11));
11067 arg10));
11071 arg11));
11073 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11076 {
11082 }
11083 }
11085 /* Attempt to simplify equality/inequality comparisons of complex
11086 values. Only lower the comparison if the result is known or
11087 can be simplified to a single scalar comparison. */
11092 {
11097 {
11100 }
11101 else
11102 {
11105 }
11108 {
11111 }
11112 else
11113 {
11116 }
11120 {
11122 {
11127 }
11128 else
11129 {
11134 }
11135 }
11139 {
11141 {
11146 }
11147 else
11148 {
11153 }
11154 }
11155 }
11167 /* Transform comparisons of the form X +- C CMP X. */
11174 {
11181 else
11184 /* (X - c) > X becomes false. */
11188 {
11192 "occur when assuming that (X - c) > X "
11194 WARN_STRICT_OVERFLOW_ALL);
11196 }
11198 /* Likewise (X + c) < X becomes false. */
11202 {
11206 "occur when assuming that "
11208 WARN_STRICT_OVERFLOW_ALL);
11210 }
11212 /* Convert (X - c) <= X to true. */
11217 {
11221 "occur when assuming that "
11223 WARN_STRICT_OVERFLOW_ALL);
11225 }
11227 /* Convert (X + c) >= X to true. */
11232 {
11236 "occur when assuming that "
11238 WARN_STRICT_OVERFLOW_ALL);
11240 }
11243 {
11244 /* Convert X + c > X and X - c < X to true for integers. */
11248 {
11251 "not occur when assuming that "
11253 WARN_STRICT_OVERFLOW_ALL);
11255 }
11260 {
11263 "not occur when assuming that "
11265 WARN_STRICT_OVERFLOW_ALL);
11267 }
11269 /* Convert X + c <= X and X - c >= X to false for integers. */
11273 {
11276 "not occur when assuming that "
11278 WARN_STRICT_OVERFLOW_ALL);
11280 }
11285 {
11288 "not occur when assuming that "
11290 WARN_STRICT_OVERFLOW_ALL);
11292 }
11293 }
11294 }
11296 /* If we are comparing an ABS_EXPR with a constant, we can
11297 convert all the cases into explicit comparisons, but they may
11298 well not be faster than doing the ABS and one comparison.
11299 But ABS (X) <= C is a range comparison, which becomes a subtraction
11300 and a comparison, and is probably faster. */
11314 /* Convert ABS_EXPR<x> >= 0 to true. */
11321 {
11324 "when simplifying comparison of "
11326 WARN_STRICT_OVERFLOW_CONDITIONAL);
11329 arg0);
11330 }
11332 /* Convert ABS_EXPR<x> < 0 to false. */
11337 {
11340 "when simplifying comparison of "
11342 WARN_STRICT_OVERFLOW_CONDITIONAL);
11345 arg0);
11346 }
11348 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11349 and similarly for >= into !=. */
11359 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11360 otherwise Y might be >= # of bits in X's type and thus e.g.
11361 (unsigned char) (1 << Y) for Y 15 might be 0.
11362 If the cast is widening, then 1 << Y should have unsigned type,
11363 otherwise if Y is number of bits in the signed shift type minus 1,
11364 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11365 31 might be 0xffffffff80000000. */
11376 {
11382 }
11394 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11395 {
11407 }
11412 /* When pedantic, a compound expression can be neither an lvalue
11413 nor an integer constant expression. */
11416 /* Don't let (0, 0) be null pointer constant. */
11422 /* An ASSERT_EXPR should never be passed to fold_binary. */
11428 }
11430 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11431 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11432 of GOTO_EXPR. */
11434 static tree
11436 {
11438 {
11445 /* ... fall through ... */
11449 }
11450 }
11452 /* Return whether the sub-tree ST contains a label which is accessible from
11453 outside the sub-tree. */
11455 static bool
11457 {
11458 return
11460 }
11462 /* Fold a ternary expression of code CODE and type TYPE with operands
11463 OP0, OP1, and OP2. Return the folded expression if folding is
11464 successful. Otherwise, return NULL_TREE. */
11466 tree
11469 {
11470 tree tem;
11477 /* If this is a commutative operation, and OP0 is a constant, move it
11478 to OP1 to reduce the number of tests below. */
11487 /* Strip any conversions that don't change the mode. This is safe
11488 for every expression, except for a comparison expression because
11489 its signedness is derived from its operands. So, in the latter
11490 case, only strip conversions that don't change the signedness.
11492 Note that this is done as an internal manipulation within the
11493 constant folder, in order to find the simplest representation of
11494 the arguments so that their form can be studied. In any cases,
11495 the appropriate type conversions should be put back in the tree
11496 that will get out of the constant folder. */
11498 {
11501 }
11504 {
11507 }
11510 {
11513 }
11516 {
11520 {
11526 }
11531 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11532 so all simple results must be passed through pedantic_non_lvalue. */
11534 {
11537 /* Only optimize constant conditions when the selected branch
11538 has the same type as the COND_EXPR. This avoids optimizing
11539 away "c ? x : throw", where the throw has a void type.
11540 Avoid throwing away that operand which contains label. */
11547 }
11549 {
11554 {
11559 {
11567 }
11571 }
11572 }
11574 /* If we have A op B ? A : C, we may be able to convert this to a
11575 simpler expression, depending on the operation and the values
11576 of B and C. Signed zeros prevent all of these transformations,
11577 for reasons given above each one.
11579 Also try swapping the arguments and inverting the conditional. */
11584 {
11588 }
11592 op2,
11595 {
11599 {
11603 }
11604 }
11606 /* If the second operand is simpler than the third, swap them
11607 since that produces better jump optimization results. */
11610 {
11612 /* See if this can be inverted. If it can't, possibly because
11613 it was a floating-point inequality comparison, don't do
11614 anything. */
11618 }
11620 /* Convert A ? 1 : 0 to simply A. */
11625 /* If we try to convert OP0 to our type, the
11626 call to fold will try to move the conversion inside
11627 a COND, which will recurse. In that case, the COND_EXPR
11628 is probably the best choice, so leave it alone. */
11632 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11633 over COND_EXPR in cases such as floating point comparisons. */
11642 arg0)));
11644 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11649 {
11650 /* sign_bit_p looks through both zero and sign extensions,
11651 but for this optimization only sign extensions are
11652 usable. */
11655 {
11658 {
11661 }
11663 }
11664 /* sign_bit_p only checks ARG1 bits within A's precision.
11665 If <sign bit of A> has wider type than A, bits outside
11666 of A's precision in <sign bit of A> need to be checked.
11667 If they are all 0, this optimization needs to be done
11668 in unsigned A's type, if they are all 1 in signed A's type,
11669 otherwise this can't be done. */
11675 {
11677 tree tem_type;
11690 {
11693 }
11695 {
11698 }
11699 else
11701 }
11704 return
11710 arg1)));
11711 }
11713 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11714 already handled above. */
11719 {
11728 }
11730 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11731 is probably obsolete because the first operand should be a
11732 truth value (that's why we have the two cases above), but let's
11733 leave it in until we can confirm this for all front-ends. */
11745 /* Disable the transformations below for vectors, since
11746 fold_binary_op_with_conditional_arg may undo them immediately,
11747 yielding an infinite loop. */
11751 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11760 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11765 {
11767 /* Only perform transformation if ARG0 is easily inverted. */
11771 ? BIT_IOR_EXPR
11774 arg1);
11775 }
11777 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11782 {
11784 /* Only perform transformation if ARG0 is easily inverted. */
11790 op2);
11791 }
11793 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11805 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11806 of fold_ternary on them. */
11816 {
11826 {
11831 {
11839 }
11841 /* Constructor elements can be subvectors. */
11844 {
11848 }
11850 /* We keep an exact subset of the constructor elements. */
11852 {
11858 {
11862 }
11870 CONSTRUCTOR_ELT
11873 }
11874 /* The bitfield references a single constructor element. */
11876 {
11881 else
11885 }
11886 }
11887 }
11889 /* A bit-field-ref that referenced the full argument can be stripped. */
11895 /* On constants we can use native encode/interpret to constant
11896 fold (nearly) all BIT_FIELD_REFs. */
11900 /* This limitation should not be necessary, we just need to
11901 round this up to mode size. */
11903 /* Need bit-shifting of the buffer to relax the following. */
11905 {
11910 /* ??? We cannot tell native_encode_expr to start at
11911 some random byte only. So limit us to a reasonable amount
11912 of work. */
11914 {
11919 {
11925 }
11926 }
11927 }
11932 /* For integers we can decompose the FMA if possible. */
11944 {
11960 {
11965 /* Make sure that the perm value is in an acceptable
11966 range. */
11975 else
11980 }
11983 {
11988 }
11993 {
11998 }
12004 {
12008 }
12013 /* Some targets are deficient and fail to expand a single
12014 argument permutation while still allowing an equivalent
12015 2-argument version. */
12019 {
12022 }
12025 {
12032 }
12036 }
12042 }
12044 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
12045 of an array (or vector). */
12047 tree
12049 {
12054 {
12057 {
12058 /* Static constructors for variably sized objects makes no sense. */
12062 }
12063 }
12074 offset_int max_index;
12079 {
12080 /* Array constructor might explicitly set index, or specify a range,
12081 or leave index NULL meaning that it is next index after previous
12082 one. */
12084 {
12087 else
12088 {
12092 }
12093 }
12094 else
12095 {
12101 }
12103 /* Do we have match? */
12107 }
12109 }
12111 /* Perform constant folding and related simplification of EXPR.
12112 The related simplifications include x*1 => x, x*0 => 0, etc.,
12113 and application of the associative law.
12114 NOP_EXPR conversions may be removed freely (as long as we
12115 are careful not to change the type of the overall expression).
12116 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12117 but we can constant-fold them if they have constant operands. */
12119 #ifdef ENABLE_FOLD_CHECKING
12120 # define fold(x) fold_1 (x)
12122 static
12123 #endif
12124 tree
12126 {
12130 tree tem;
12133 /* Return right away if a constant. */
12137 /* CALL_EXPR-like objects with variable numbers of operands are
12138 treated specially. */
12140 {
12142 {
12145 }
12147 }
12150 {
12155 {
12173 }
12174 }
12177 {
12179 {
12186 {
12191 }
12194 }
12196 /* Return a VECTOR_CST if possible. */
12198 {
12204 tree val;
12210 }
12218 }
12220 #ifdef ENABLE_FOLD_CHECKING
12221 #undef fold
12228 /* When --enable-checking=fold, compute a digest of expr before
12229 and after actual fold call to see if fold did not accidentally
12230 change original expr. */
12232 tree
12234 {
12235 tree ret;
12255 }
12257 void
12259 {
12270 }
12272 static void
12274 {
12276 }
12278 static void
12281 {
12287 recursive_label:
12297 {
12298 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12303 }
12310 {
12311 /* Allow these fields to be modified. */
12312 tree tmp;
12320 {
12323 }
12324 }
12335 {
12338 {
12353 }
12357 {
12370 }
12387 {
12393 }
12396 {
12398 {
12401 }
12403 }
12414 {
12417 }
12427 }
12428 }
12430 /* Helper function for outputting the checksum of a tree T. When
12431 debugging with gdb, you can "define mynext" to be "next" followed
12432 by "call debug_fold_checksum (op0)", then just trace down till the
12433 outputs differ. */
12435 DEBUG_FUNCTION void
12437 {
12452 }
12454 #endif
12456 /* Fold a unary tree expression with code CODE of type TYPE with an
12457 operand OP0. LOC is the location of the resulting expression.
12458 Return a folded expression if successful. Otherwise, return a tree
12459 expression with code CODE of type TYPE with an operand OP0. */
12461 tree
12464 {
12465 tree tem;
12466 #ifdef ENABLE_FOLD_CHECKING
12475 #endif
12481 #ifdef ENABLE_FOLD_CHECKING
12488 #endif
12490 }
12492 /* Fold a binary tree expression with code CODE of type TYPE with
12493 operands OP0 and OP1. LOC is the location of the resulting
12494 expression. Return a folded expression if successful. Otherwise,
12495 return a tree expression with code CODE of type TYPE with operands
12496 OP0 and OP1. */
12498 tree
12501 MEM_STAT_DECL)
12502 {
12503 tree tem;
12504 #ifdef ENABLE_FOLD_CHECKING
12521 #endif
12527 #ifdef ENABLE_FOLD_CHECKING
12542 #endif
12544 }
12546 /* Fold a ternary tree expression with code CODE of type TYPE with
12547 operands OP0, OP1, and OP2. Return a folded expression if
12548 successful. Otherwise, return a tree expression with code CODE of
12549 type TYPE with operands OP0, OP1, and OP2. */
12551 tree
12554 {
12555 tree tem;
12556 #ifdef ENABLE_FOLD_CHECKING
12580 #endif
12587 #ifdef ENABLE_FOLD_CHECKING
12610 #endif
12612 }
12614 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12615 arguments in ARGARRAY, and a null static chain.
12616 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12617 of type TYPE from the given operands as constructed by build_call_array. */
12619 tree
12622 {
12623 tree tem;
12624 #ifdef ENABLE_FOLD_CHECKING
12643 #endif
12649 #ifdef ENABLE_FOLD_CHECKING
12665 #endif
12667 }
12669 /* Perform constant folding and related simplification of initializer
12670 expression EXPR. These behave identically to "fold_buildN" but ignore
12671 potential run-time traps and exceptions that fold must preserve. */
12673 #define START_FOLD_INIT \
12674 int saved_signaling_nans = flag_signaling_nans;\
12675 int saved_trapping_math = flag_trapping_math;\
12676 int saved_rounding_math = flag_rounding_math;\
12677 int saved_trapv = flag_trapv;\
12678 int saved_folding_initializer = folding_initializer;\
12679 flag_signaling_nans = 0;\
12680 flag_trapping_math = 0;\
12681 flag_rounding_math = 0;\
12682 flag_trapv = 0;\
12683 folding_initializer = 1;
12685 #define END_FOLD_INIT \
12686 flag_signaling_nans = saved_signaling_nans;\
12687 flag_trapping_math = saved_trapping_math;\
12688 flag_rounding_math = saved_rounding_math;\
12689 flag_trapv = saved_trapv;\
12690 folding_initializer = saved_folding_initializer;
12692 tree
12695 {
12696 tree result;
12697 START_FOLD_INIT;
12701 END_FOLD_INIT;
12703 }
12705 tree
12708 {
12709 tree result;
12710 START_FOLD_INIT;
12714 END_FOLD_INIT;
12716 }
12718 tree
12721 {
12722 tree result;
12723 START_FOLD_INIT;
12727 END_FOLD_INIT;
12729 }
12731 #undef START_FOLD_INIT
12732 #undef END_FOLD_INIT
12734 /* Determine if first argument is a multiple of second argument. Return 0 if
12735 it is not, or we cannot easily determined it to be.
12737 An example of the sort of thing we care about (at this point; this routine
12738 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12739 fold cases do now) is discovering that
12741 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12743 is a multiple of
12745 SAVE_EXPR (J * 8)
12747 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12749 This code also handles discovering that
12751 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12753 is a multiple of 8 so we don't have to worry about dealing with a
12754 possible remainder.
12756 Note that we *look* inside a SAVE_EXPR only to determine how it was
12757 calculated; it is not safe for fold to do much of anything else with the
12758 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12759 at run time. For example, the latter example above *cannot* be implemented
12760 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12761 evaluation time of the original SAVE_EXPR is not necessarily the same at
12762 the time the new expression is evaluated. The only optimization of this
12763 sort that would be valid is changing
12765 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12767 divided by 8 to
12769 SAVE_EXPR (I) * SAVE_EXPR (J)
12771 (where the same SAVE_EXPR (J) is used in the original and the
12772 transformed version). */
12774 int
12776 {
12784 {
12786 /* Bitwise and provides a power of two multiple. If the mask is
12787 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12790 /* FALLTHRU */
12803 {
12807 /* const_binop may not detect overflow correctly,
12808 so check for it explicitly here. */
12812 size_one_node,
12813 op1)))
12816 }
12820 /* Can't handle conversions from non-integral or wider integral type. */
12826 /* .. fall through ... */
12843 SIGNED);
12847 }
12848 }
12850 #define tree_expr_nonnegative_warnv_p(X, Y) \
12853 #define RECURSE(X) \
12854 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12856 /* Return true if CODE or TYPE is known to be non-negative. */
12858 static bool
12860 {
12863 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12864 have a signed:1 type (where the value is -1 and 0). */
12867 }
12869 /* Return true if (CODE OP0) is known to be non-negative. If the return
12870 value is based on the assumption that signed overflow is undefined,
12871 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12872 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12874 bool
12877 {
12882 {
12884 /* We can't return 1 if flag_wrapv is set because
12885 ABS_EXPR<INT_MIN> = INT_MIN. */
12889 {
12892 }
12900 CASE_CONVERT:
12901 {
12906 {
12910 {
12914 }
12915 }
12917 {
12923 }
12924 }
12929 }
12931 /* We don't know sign of `t', so be conservative and return false. */
12933 }
12935 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12936 value is based on the assumption that signed overflow is undefined,
12937 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12938 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12940 bool
12944 {
12949 {
12955 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12956 both unsigned and at least 2 bits shorter than the result. */
12960 {
12965 {
12969 }
12970 }
12975 {
12976 /* x * x is always non-negative for floating point x
12977 or without overflow. */
12980 {
12985 }
12986 }
12988 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12989 both unsigned and their total bits is shorter than the result. */
12993 {
13012 {
13022 }
13023 }
13050 }
13052 /* We don't know sign of `t', so be conservative and return false. */
13054 }
13056 /* Return true if T is known to be non-negative. If the return
13057 value is based on the assumption that signed overflow is undefined,
13058 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13059 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13061 bool
13063 {
13068 {
13082 /* Limit the depth of recursion to avoid quadratic behavior.
13083 This is expected to catch almost all occurrences in practice.
13084 If this code misses important cases that unbounded recursion
13085 would not, passes that need this information could be revised
13086 to provide it through dataflow propagation. */
13094 }
13095 }
13097 /* Return true if T is known to be non-negative. If the return
13098 value is based on the assumption that signed overflow is undefined,
13099 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13100 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13102 bool
13105 {
13107 {
13108 CASE_CFN_ACOS:
13109 CASE_CFN_ACOSH:
13110 CASE_CFN_CABS:
13111 CASE_CFN_COSH:
13112 CASE_CFN_ERFC:
13113 CASE_CFN_EXP:
13114 CASE_CFN_EXP10:
13115 CASE_CFN_EXP2:
13116 CASE_CFN_FABS:
13117 CASE_CFN_FDIM:
13118 CASE_CFN_HYPOT:
13119 CASE_CFN_POW10:
13120 CASE_CFN_FFS:
13121 CASE_CFN_PARITY:
13122 CASE_CFN_POPCOUNT:
13123 CASE_CFN_CLZ:
13124 CASE_CFN_CLRSB:
13127 /* Always true. */
13130 CASE_CFN_SQRT:
13131 /* sqrt(-0.0) is -0.0. */
13136 CASE_CFN_ASINH:
13137 CASE_CFN_ATAN:
13138 CASE_CFN_ATANH:
13139 CASE_CFN_CBRT:
13140 CASE_CFN_CEIL:
13141 CASE_CFN_ERF:
13142 CASE_CFN_EXPM1:
13143 CASE_CFN_FLOOR:
13144 CASE_CFN_FMOD:
13145 CASE_CFN_FREXP:
13146 CASE_CFN_ICEIL:
13147 CASE_CFN_IFLOOR:
13148 CASE_CFN_IRINT:
13149 CASE_CFN_IROUND:
13150 CASE_CFN_LCEIL:
13151 CASE_CFN_LDEXP:
13152 CASE_CFN_LFLOOR:
13153 CASE_CFN_LLCEIL:
13154 CASE_CFN_LLFLOOR:
13155 CASE_CFN_LLRINT:
13156 CASE_CFN_LLROUND:
13157 CASE_CFN_LRINT:
13158 CASE_CFN_LROUND:
13159 CASE_CFN_MODF:
13160 CASE_CFN_NEARBYINT:
13161 CASE_CFN_RINT:
13162 CASE_CFN_ROUND:
13163 CASE_CFN_SCALB:
13164 CASE_CFN_SCALBLN:
13165 CASE_CFN_SCALBN:
13166 CASE_CFN_SIGNBIT:
13167 CASE_CFN_SIGNIFICAND:
13168 CASE_CFN_SINH:
13169 CASE_CFN_TANH:
13170 CASE_CFN_TRUNC:
13171 /* True if the 1st argument is nonnegative. */
13174 CASE_CFN_FMAX:
13175 /* True if the 1st OR 2nd arguments are nonnegative. */
13178 CASE_CFN_FMIN:
13179 /* True if the 1st AND 2nd arguments are nonnegative. */
13182 CASE_CFN_COPYSIGN:
13183 /* True if the 2nd argument is nonnegative. */
13186 CASE_CFN_POWI:
13187 /* True if the 1st argument is nonnegative or the second
13188 argument is an even integer. */
13194 CASE_CFN_POW:
13195 /* True if the 1st argument is nonnegative or the second
13196 argument is an even integer valued real. */
13198 {
13199 REAL_VALUE_TYPE c;
13200 HOST_WIDE_INT n;
13205 {
13206 REAL_VALUE_TYPE cint;
13210 }
13211 }
13216 }
13218 }
13220 /* Return true if T is known to be non-negative. If the return
13221 value is based on the assumption that signed overflow is undefined,
13222 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13223 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13225 static bool
13227 {
13233 {
13235 {
13239 /* If the initializer is non-void, then it's a normal expression
13240 that will be assigned to the slot. */
13244 /* Otherwise, the initializer sets the slot in some way. One common
13245 way is an assignment statement at the end of the initializer. */
13247 {
13255 else
13257 }
13263 }
13266 {
13272 arg0,
13273 arg1,
13275 }
13288 }
13289 }
13291 #undef RECURSE
13292 #undef tree_expr_nonnegative_warnv_p
13294 /* Return true if T is known to be non-negative. If the return
13295 value is based on the assumption that signed overflow is undefined,
13296 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13297 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13299 bool
13301 {
13308 {
13330 }
13333 {
13359 }
13360 }
13362 /* Return true if `t' is known to be non-negative. Handle warnings
13363 about undefined signed overflow. */
13365 bool
13367 {
13374 "determining that expression is always "
13376 WARN_STRICT_OVERFLOW_MISC);
13378 }
13381 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13382 For floating point we further ensure that T is not denormal.
13383 Similar logic is present in nonzero_address in rtlanal.h.
13385 If the return value is based on the assumption that signed overflow
13386 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13387 change *STRICT_OVERFLOW_P. */
13389 bool
13392 {
13394 {
13397 strict_overflow_p);
13400 {
13406 strict_overflow_p));
13407 }
13412 strict_overflow_p);
13416 }
13419 }
13421 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13422 For floating point we further ensure that T is not denormal.
13423 Similar logic is present in nonzero_address in rtlanal.h.
13425 If the return value is based on the assumption that signed overflow
13426 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13427 change *STRICT_OVERFLOW_P. */
13429 bool
13431 tree type,
13432 tree op0,
13434 {
13437 {
13441 {
13442 /* With the presence of negative values it is hard
13443 to say something. */
13450 /* One of operands must be positive and the other non-negative. */
13451 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13452 overflows, on a twos-complement machine the sum of two
13453 nonnegative numbers can never be zero. */
13455 strict_overflow_p)
13457 strict_overflow_p));
13458 }
13463 {
13465 strict_overflow_p)
13467 strict_overflow_p))
13468 {
13471 }
13472 }
13481 {
13484 }
13491 {
13495 /* When both operands are nonzero, then MAX must be too. */
13497 strict_overflow_p))
13500 /* MAX where operand 0 is positive is positive. */
13502 strict_overflow_p);
13503 }
13504 /* MAX where operand 1 is positive is positive. */
13509 {
13513 }
13518 strict_overflow_p)
13520 strict_overflow_p));
13524 }
13527 }
13529 /* Return true when T is an address and is known to be nonzero.
13530 For floating point we further ensure that T is not denormal.
13531 Similar logic is present in nonzero_address in rtlanal.h.
13533 If the return value is based on the assumption that signed overflow
13534 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13535 change *STRICT_OVERFLOW_P. */
13537 bool
13539 {
13542 {
13547 {
13559 /* For objects in symbol table check if we know they are non-zero.
13560 Don't do anything for variables and functions before symtab is built;
13561 it is quite possible that they will be declared weak later. */
13566 /* Function local objects are never NULL. */
13573 /* Constants are never weak. */
13578 }
13586 {
13590 }
13595 }
13597 }
13599 #define integer_valued_real_p(X) \
13602 #define RECURSE(X) \
13603 ((integer_valued_real_p) (X, depth + 1))
13605 /* Return true if the floating point result of (CODE OP0) has an
13606 integer value. We also allow +Inf, -Inf and NaN to be considered
13607 integer values. Return false for signaling NaN.
13609 DEPTH is the current nesting depth of the query. */
13611 bool
13613 {
13615 {
13622 CASE_CONVERT:
13623 {
13630 }
13634 }
13636 }
13638 /* Return true if the floating point result of (CODE OP0 OP1) has an
13639 integer value. We also allow +Inf, -Inf and NaN to be considered
13640 integer values. Return false for signaling NaN.
13642 DEPTH is the current nesting depth of the query. */
13644 bool
13646 {
13648 {
13658 }
13660 }
13662 /* Return true if the floating point result of calling FNDECL with arguments
13663 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13664 considered integer values. Return false for signaling NaN. If FNDECL
13665 takes fewer than 2 arguments, the remaining ARGn are null.
13667 DEPTH is the current nesting depth of the query. */
13669 bool
13671 {
13673 {
13674 CASE_CFN_CEIL:
13675 CASE_CFN_FLOOR:
13676 CASE_CFN_NEARBYINT:
13677 CASE_CFN_RINT:
13678 CASE_CFN_ROUND:
13679 CASE_CFN_TRUNC:
13682 CASE_CFN_FMIN:
13683 CASE_CFN_FMAX:
13688 }
13690 }
13692 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13693 has an integer value. We also allow +Inf, -Inf and NaN to be
13694 considered integer values. Return false for signaling NaN.
13696 DEPTH is the current nesting depth of the query. */
13698 bool
13700 {
13702 {
13710 /* Limit the depth of recursion to avoid quadratic behavior.
13711 This is expected to catch almost all occurrences in practice.
13712 If this code misses important cases that unbounded recursion
13713 would not, passes that need this information could be revised
13714 to provide it through dataflow propagation. */
13718 depth));
13722 }
13724 }
13726 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13727 has an integer value. We also allow +Inf, -Inf and NaN to be
13728 considered integer values. Return false for signaling NaN.
13730 DEPTH is the current nesting depth of the query. */
13732 static bool
13734 {
13736 {
13747 }
13749 }
13751 #undef RECURSE
13752 #undef integer_valued_real_p
13754 /* Return true if the floating point expression T has an integer value.
13755 We also allow +Inf, -Inf and NaN to be considered integer values.
13756 Return false for signaling NaN.
13758 DEPTH is the current nesting depth of the query. */
13760 bool
13762 {
13768 {
13784 }
13787 {
13793 {
13802 }
13806 }
13807 }
13809 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13810 attempt to fold the expression to a constant without modifying TYPE,
13811 OP0 or OP1.
13813 If the expression could be simplified to a constant, then return
13814 the constant. If the expression would not be simplified to a
13815 constant, then return NULL_TREE. */
13817 tree
13819 {
13822 }
13824 /* Given the components of a unary expression CODE, TYPE and OP0,
13825 attempt to fold the expression to a constant without modifying
13826 TYPE or OP0.
13828 If the expression could be simplified to a constant, then return
13829 the constant. If the expression would not be simplified to a
13830 constant, then return NULL_TREE. */
13832 tree
13834 {
13837 }
13839 /* If EXP represents referencing an element in a constant string
13840 (either via pointer arithmetic or array indexing), return the
13841 tree representing the value accessed, otherwise return NULL. */
13843 tree
13845 {
13849 {
13851 tree index;
13852 tree string;
13857 else
13858 {
13862 /* Optimize the special-case of a zero lower bound.
13864 We convert the low_bound to sizetype to avoid some problems
13865 with constant folding. (E.g. suppose the lower bound is 1,
13866 and its mode is QI. Without the conversion,l (ARRAY
13867 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13868 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13874 }
13887 }
13889 }
13891 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13892 an integer constant, real, or fixed-point constant.
13894 TYPE is the type of the result. */
13896 static tree
13898 {
13902 {
13904 {
13911 }
13918 {
13919 FIXED_VALUE_TYPE f;
13924 /* Propagate overflow flags. */
13928 }
13932 }
13935 }
13937 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13938 an integer constant or real constant.
13940 TYPE is the type of the result. */
13942 tree
13944 {
13948 {
13950 {
13951 /* If the value is unsigned or non-negative, then the absolute value
13952 is the same as the ordinary value. */
13956 /* If the value is negative, then the absolute value is
13957 its negation. */
13958 else
13959 {
13964 }
13965 }
13971 else
13977 }
13980 }
13982 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13983 constant. TYPE is the type of the result. */
13985 static tree
13987 {
13991 }
13993 /* Given CODE, a relational operator, the target type, TYPE and two
13994 constant operands OP0 and OP1, return the result of the
13995 relational operation. If the result is not a compile time
13996 constant, then return NULL_TREE. */
13998 static tree
14000 {
14003 /* From here on, the only cases we handle are when the result is
14004 known to be a constant. */
14007 {
14011 /* Handle the cases where either operand is a NaN. */
14013 {
14015 {
14043 }
14046 }
14049 }
14052 {
14056 }
14058 /* Handle equality/inequality of complex constants. */
14060 {
14071 else
14073 }
14076 {
14078 {
14079 /* Have vector comparison with scalar boolean result. */
14084 {
14089 }
14093 }
14100 {
14112 }
14115 }
14117 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14119 To compute GT, swap the arguments and do LT.
14120 To compute GE, do LT and invert the result.
14121 To compute LE, swap the arguments, do LT and invert the result.
14122 To compute NE, do EQ and invert the result.
14124 Therefore, the code below must handle only EQ and LT. */
14127 {
14130 }
14132 /* Note that it is safe to invert for real values here because we
14133 have already handled the one case that it matters. */
14137 {
14140 }
14142 /* Compute a result for LT or EQ if args permit;
14143 Otherwise return T. */
14145 {
14148 else
14150 }
14151 else
14157 }
14159 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14160 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14161 itself. */
14163 tree
14165 {
14166 /* If the expression does not have side effects then we don't have to wrap
14167 it with a cleanup point expression. */
14171 /* If the expression is a return, check to see if the expression inside the
14172 return has no side effects or the right hand side of the modify expression
14173 inside the return. If either don't have side effects set we don't need to
14174 wrap the expression in a cleanup point expression. Note we don't check the
14175 left hand side of the modify because it should always be a return decl. */
14177 {
14184 }
14187 }
14189 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14190 of an indirection through OP0, or NULL_TREE if no simplification is
14191 possible. */
14193 tree
14195 {
14197 tree subtype;
14205 {
14208 /* *&CONST_DECL -> to the value of the const decl. */
14211 /* *&p => p; make sure to handle *&"str"[cst] here. */
14213 {
14217 else
14219 }
14220 /* *(foo *)&fooarray => fooarray[0] */
14223 && (!in_gimple_form
14225 {
14235 }
14236 /* *(foo *)&complexfoo => __real__ complexfoo */
14240 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14243 {
14247 }
14248 }
14252 {
14258 {
14259 tree op00type;
14263 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14266 {
14268 unsigned HOST_WIDE_INT max_offset
14273 {
14280 }
14281 }
14282 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14285 {
14289 }
14290 /* ((foo *)&fooarray)[1] => fooarray[1] */
14293 {
14303 }
14304 }
14305 }
14307 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14310 && (!in_gimple_form
14312 {
14313 tree type_domain;
14323 NULL_TREE);
14324 }
14327 }
14329 /* Builds an expression for an indirection through T, simplifying some
14330 cases. */
14332 tree
14334 {
14342 }
14344 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14346 tree
14348 {
14353 else
14355 }
14357 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14358 whose result is ignored. The type of the returned tree need not be
14359 the same as the original expression. */
14361 tree
14363 {
14369 {
14380 else
14386 {
14402 }
14407 }
14408 }
14410 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14412 tree
14414 {
14420 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14421 have to do anything. Only do this when we are not given a const,
14422 because in that case, this check is more expensive than just
14423 doing it. */
14425 {
14430 }
14432 /* If divisor is a power of two, simplify this to bit manipulation. */
14434 {
14436 {
14450 }
14451 else
14452 {
14453 tree t;
14459 }
14460 }
14461 else
14462 {
14467 }
14470 }
14472 /* Likewise, but round down. */
14474 tree
14476 {
14483 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14484 have to do anything. Only do this when we are not given a const,
14485 because in that case, this check is more expensive than just
14486 doing it. */
14488 {
14493 }
14495 /* If divisor is a power of two, simplify this to bit manipulation. */
14497 {
14498 tree t;
14502 }
14503 else
14504 {
14509 }
14512 }
14514 /* Returns the pointer to the base of the object addressed by EXP and
14515 extracts the information about the offset of the access, storing it
14516 to PBITPOS and POFFSET. */
14518 static tree
14521 {
14522 tree core;
14523 machine_mode mode;
14525 HOST_WIDE_INT bitsize;
14529 {
14534 }
14535 else
14536 {
14540 }
14543 }
14545 /* Returns true if addresses of E1 and E2 differ by a constant, false
14546 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14548 bool
14550 {
14564 {
14574 }
14576 {
14577 /* If only one of the offsets is non-constant, the difference cannot
14578 be a constant. */
14580 }
14581 else
14586 }
14588 /* Return OFF converted to a pointer offset type suitable as offset for
14589 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14590 tree
14592 {
14594 }
14596 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14597 tree
14599 {
14602 }
14604 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14605 tree
14607 {
14610 }
14612 /* Return a char pointer for a C string if it is a string constant
14613 or sum of string constant and integer constant. */
14617 {
14618 tree offset_node;
14631 }