| blob | 603aff096590ac2cd65e2c23a08972675e59039d |
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. */
83 /* Nonzero if we are folding constants inside an initializer; zero
84 otherwise. */
87 /* The following constants represent a bit based encoding of GCC's
88 comparison operators. This encoding simplifies transformations
89 on relational comparison operators, such as AND and OR. */
107 };
145 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
146 Otherwise, return LOC. */
148 static location_t
150 {
153 }
155 /* Similar to protected_set_expr_location, but never modify x in place,
156 if location can and needs to be set, unshare it. */
160 {
166 {
169 }
171 }
172 \f
173 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
174 division and returns the quotient. Otherwise returns
175 NULL_TREE. */
177 tree
179 {
180 widest_int quo;
187 }
188 \f
189 /* This is nonzero if we should defer warnings about undefined
190 overflow. This facility exists because these warnings are a
191 special case. The code to estimate loop iterations does not want
192 to issue any warnings, since it works with expressions which do not
193 occur in user code. Various bits of cleanup code call fold(), but
194 only use the result if it has certain characteristics (e.g., is a
195 constant); that code only wants to issue a warning if the result is
196 used. */
200 /* If a warning about undefined overflow is deferred, this is the
201 warning. Note that this may cause us to turn two warnings into
202 one, but that is fine since it is sufficient to only give one
203 warning per expression. */
207 /* If a warning about undefined overflow is deferred, this is the
208 level at which the warning should be emitted. */
212 /* Start deferring overflow warnings. We could use a stack here to
213 permit nested calls, but at present it is not necessary. */
215 void
217 {
219 }
221 /* Stop deferring overflow warnings. If there is a pending warning,
222 and ISSUE is true, then issue the warning if appropriate. STMT is
223 the statement with which the warning should be associated (used for
224 location information); STMT may be NULL. CODE is the level of the
225 warning--a warn_strict_overflow_code value. This function will use
226 the smaller of CODE and the deferred code when deciding whether to
227 issue the warning. CODE may be zero to mean to always use the
228 deferred code. */
230 void
232 {
234 location_t locus;
239 {
245 }
256 /* Use the smallest code level when deciding to issue the
257 warning. */
266 else
269 }
271 /* Stop deferring overflow warnings, ignoring any deferred
272 warnings. */
274 void
276 {
278 }
280 /* Whether we are deferring overflow warnings. */
282 bool
284 {
286 }
288 /* This is called when we fold something based on the fact that signed
289 overflow is undefined. */
291 void
293 {
295 {
298 {
301 }
302 }
305 }
306 \f
307 /* Return true if the built-in mathematical function specified by CODE
308 is odd, i.e. -f(x) == f(-x). */
310 bool
312 {
314 {
315 CASE_CFN_ASIN:
316 CASE_CFN_ASINH:
317 CASE_CFN_ATAN:
318 CASE_CFN_ATANH:
319 CASE_CFN_CASIN:
320 CASE_CFN_CASINH:
321 CASE_CFN_CATAN:
322 CASE_CFN_CATANH:
323 CASE_CFN_CBRT:
324 CASE_CFN_CPROJ:
325 CASE_CFN_CSIN:
326 CASE_CFN_CSINH:
327 CASE_CFN_CTAN:
328 CASE_CFN_CTANH:
329 CASE_CFN_ERF:
330 CASE_CFN_LLROUND:
331 CASE_CFN_LROUND:
332 CASE_CFN_ROUND:
333 CASE_CFN_SIN:
334 CASE_CFN_SINH:
335 CASE_CFN_TAN:
336 CASE_CFN_TANH:
337 CASE_CFN_TRUNC:
340 CASE_CFN_LLRINT:
341 CASE_CFN_LRINT:
342 CASE_CFN_NEARBYINT:
343 CASE_CFN_RINT:
348 }
350 }
352 /* Check whether we may negate an integer constant T without causing
353 overflow. */
355 bool
357 {
358 tree type;
367 }
369 /* Determine whether an expression T can be cheaply negated using
370 the function negate_expr without introducing undefined overflow. */
372 static bool
374 {
375 tree type;
384 {
389 /* Check that -CST will not overflow type. */
402 /* We want to canonicalize to positive real constants. Pretend
403 that only negative ones can be easily negated. */
411 {
422 }
437 /* -(A + B) -> (-B) - A. */
442 /* -(A + B) -> (-A) - B. */
446 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
457 /* INT_MIN/n * n doesn't overflow while negating one operand it does
458 if n is a power of two. */
467 /* Fall through. */
482 /* In general we can't negate B in A / B, because if A is INT_MIN and
483 B is 1, we may turn this into INT_MIN / -1 which is undefined
484 and actually traps on some architectures. */
493 /* Negate -((double)float) as (double)(-float). */
495 {
499 }
503 /* Negate -f(x) as f(-x). */
509 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
511 {
515 }
520 }
522 }
524 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
525 simplification is possible.
526 If negate_expr_p would return true for T, NULL_TREE will never be
527 returned. */
529 static tree
531 {
533 tree tem;
536 {
537 /* Convert - (~A) to A + 1. */
563 {
568 }
572 {
577 {
581 }
584 }
607 {
608 /* -(A + B) -> (-B) - A. */
612 {
616 }
618 /* -(A + B) -> (-A) - B. */
620 {
624 }
625 }
629 /* - (A - B) -> B - A */
641 /* Fall through. */
645 {
654 }
666 /* In general we can't negate B in A / B, because if A is INT_MIN and
667 B is 1, we may turn this into INT_MIN / -1 which is undefined
668 and actually traps on some architectures. */
680 /* Convert -((double)float) into (double)(-float). */
682 {
686 }
690 /* Negate -f(x) as f(-x). */
693 {
699 }
703 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
705 {
708 {
715 }
716 }
721 }
724 }
726 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
727 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
728 return NULL_TREE. */
730 static tree
732 {
734 location_t loc;
747 }
748 \f
749 /* Split a tree IN into a constant, literal and variable parts that could be
750 combined with CODE to make IN. "constant" means an expression with
751 TREE_CONSTANT but that isn't an actual constant. CODE must be a
752 commutative arithmetic operation. Store the constant part into *CONP,
753 the literal in *LITP and return the variable part. If a part isn't
754 present, set it to null. If the tree does not decompose in this way,
755 return the entire tree as the variable part and the other parts as null.
757 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
758 case, we negate an operand that was subtracted. Except if it is a
759 literal for which we use *MINUS_LITP instead.
761 If NEGATE_P is true, we are negating all of IN, again except a literal
762 for which we use *MINUS_LITP instead. If a variable part is of pointer
763 type, it is negated after converting to TYPE. This prevents us from
764 generating illegal MINUS pointer expression. LOC is the location of
765 the converted variable part.
767 If IN is itself a literal or constant, return it as appropriate.
769 Note that we do not guarantee that any of the three values will be the
770 same type as IN, but they will have the same signedness and mode. */
772 static tree
775 {
782 /* Strip any conversions that don't change the machine mode or signedness. */
791 /* We can associate addition and subtraction together (even
792 though the C standard doesn't say so) for integers because
793 the value is not affected. For reals, the value might be
794 affected, so we can't. */
797 {
803 /* First see if either of the operands is a literal, then a constant. */
816 /* If we haven't dealt with either operand, this is not a case we can
817 decompose. Otherwise, VAR is either of the ones remaining, if any. */
822 else
825 /* Now do any needed negations. */
831 {
832 /* Convert to TYPE before negating. */
835 }
836 }
841 {
842 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
843 when IN is constant. */
846 }
847 else
851 {
858 {
859 /* Convert to TYPE before negating. */
862 }
863 }
866 }
868 /* Re-associate trees split by the above function. T1 and T2 are
869 either expressions to associate or null. Return the new
870 expression, if any. LOC is the location of the new expression. If
871 we build an operation, do it in TYPE and with CODE. */
873 static tree
875 {
881 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
882 try to fold this since we will have infinite recursion. But do
883 deal with any NEGATE_EXPRs. */
886 {
888 {
901 }
903 {
906 }
910 }
914 }
915 \f
916 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
917 for use in int_const_binop, size_binop and size_diffop. */
919 static bool
921 {
928 {
937 }
942 }
945 /* Combine two integer constants ARG1 and ARG2 under operation CODE
946 to produce a new constant. Return NULL_TREE if we don't know how
947 to evaluate CODE at compile-time. */
949 static tree
952 {
953 wide_int res;
954 tree t;
962 {
978 {
982 else
984 }
987 /* It's unclear from the C standard whether shifts can overflow.
988 The following code ignores overflow; perhaps a C standard
989 interpretation ruling is needed. */
991 else
998 {
1002 else
1004 }
1008 else
1087 }
1095 }
1097 tree
1099 {
1101 }
1103 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1104 constant. We assume ARG1 and ARG2 have the same data type, or at least
1105 are the same kind of constant and the same machine mode. Return zero if
1106 combining the constants is not allowed in the current operating mode. */
1108 static tree
1110 {
1111 /* Sanity check for the recursive cases. */
1119 {
1125 }
1128 {
1129 machine_mode mode;
1130 REAL_VALUE_TYPE d1;
1131 REAL_VALUE_TYPE d2;
1132 REAL_VALUE_TYPE value;
1133 REAL_VALUE_TYPE result;
1137 /* The following codes are handled by real_arithmetic. */
1139 {
1150 }
1158 /* Don't perform operation if we honor signaling NaNs and
1159 either operand is a signaling NaN. */
1165 /* Don't perform operation if it would raise a division
1166 by zero exception. */
1172 /* If either operand is a NaN, just return it. Otherwise, set up
1173 for floating-point trap; we return an overflow. */
1175 {
1176 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1177 is off. */
1181 }
1183 {
1184 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1185 is off. */
1189 }
1194 /* Don't constant fold this floating point operation if
1195 the result has overflowed and flag_trapping_math. */
1203 /* Don't constant fold this floating point operation if the
1204 result may dependent upon the run-time rounding mode and
1205 flag_rounding_math is set, or if GCC's software emulation
1206 is unable to accurately represent the result. */
1216 }
1219 {
1220 FIXED_VALUE_TYPE f1;
1221 FIXED_VALUE_TYPE f2;
1222 FIXED_VALUE_TYPE result;
1227 /* The following codes are handled by fixed_arithmetic. */
1229 {
1241 {
1248 }
1253 }
1260 /* Propagate overflow flags. */
1264 }
1267 {
1276 {
1287 mpc_mul);
1301 mpc_div);
1302 /* Fallthru. */
1308 {
1309 /* Keep this algorithm in sync with
1310 tree-complex.c:expand_complex_div_straight().
1312 Expand complex division to scalars, straightforward algorithm.
1313 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1314 t = br*br + bi*bi
1315 */
1316 tree magsquared
1320 tree t1
1324 tree t2
1331 }
1332 else
1333 {
1334 /* Keep this algorithm in sync with
1335 tree-complex.c:expand_complex_div_wide().
1337 Expand complex division to scalars, modified algorithm to minimize
1338 overflow with wide input ranges. */
1344 {
1345 /* In the TRUE branch, we compute
1346 ratio = br/bi;
1347 div = (br * ratio) + bi;
1348 tr = (ar * ratio) + ai;
1349 ti = (ai * ratio) - ar;
1350 tr = tr / div;
1351 ti = ti / div; */
1362 }
1363 else
1364 {
1365 /* In the FALSE branch, we compute
1366 ratio = d/c;
1367 divisor = (d * ratio) + c;
1368 tr = (b * ratio) + a;
1369 ti = b - (a * ratio);
1370 tr = tr / div;
1371 ti = ti / div; */
1383 }
1384 }
1389 }
1393 }
1397 {
1403 {
1409 /* It is possible that const_binop cannot handle the given
1410 code and return NULL_TREE */
1413 }
1416 }
1418 /* Shifts allow a scalar offset for a vector. */
1421 {
1427 {
1432 /* It is possible that const_binop cannot handle the given
1433 code and return NULL_TREE. */
1436 }
1439 }
1441 }
1443 /* Overload that adds a TYPE parameter to be able to dispatch
1444 to fold_relational_const. */
1446 tree
1448 {
1452 /* ??? Until we make the const_binop worker take the type of the
1453 result as argument put those cases that need it here. */
1455 {
1466 {
1482 {
1488 }
1491 }
1497 {
1522 {
1535 }
1538 }
1541 }
1546 /* Make sure type and arg0 have the same saturating flag. */
1551 }
1553 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1554 Return zero if computing the constants is not possible. */
1556 tree
1558 {
1559 /* Don't perform the operation, other than NEGATE and ABS, if
1560 flag_signaling_nans is on and the operand is a signaling NaN. */
1569 {
1570 CASE_CONVERT:
1577 /* If the source address is 0, and the source address space
1578 cannot have a valid object at 0, fold to dest type null. */
1589 {
1590 /* Can't call fold_negate_const directly here as that doesn't
1591 handle all cases and we might not be able to negate some
1592 constants. */
1597 }
1606 {
1610 }
1616 /* Perform BIT_NOT_EXPR on each element individually. */
1618 {
1620 tree elem;
1625 {
1631 }
1634 }
1656 {
1675 else
1679 {
1683 }
1686 }
1691 {
1705 {
1710 }
1713 {
1717 }
1720 }
1724 }
1727 }
1729 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1730 indicates which particular sizetype to create. */
1732 tree
1734 {
1736 }
1737 \f
1738 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1739 is a tree code. The type of the result is taken from the operands.
1740 Both must be equivalent integer types, ala int_binop_types_match_p.
1741 If the operands are constant, so is the result. */
1743 tree
1745 {
1754 /* Handle the special case of two integer constants faster. */
1756 {
1757 /* And some specific cases even faster than that. */
1759 {
1764 }
1766 {
1769 }
1771 {
1774 }
1776 /* Handle general case of two integer constants. For sizetype
1777 constant calculations we always want to know about overflow,
1778 even in the unsigned case. */
1780 }
1783 }
1785 /* Given two values, either both of sizetype or both of bitsizetype,
1786 compute the difference between the two values. Return the value
1787 in signed type corresponding to the type of the operands. */
1789 tree
1791 {
1793 tree ctype;
1798 /* If the type is already signed, just do the simple thing. */
1806 else
1809 /* If either operand is not a constant, do the conversions to the signed
1810 type and subtract. The hardware will do the right thing with any
1811 overflow in the subtraction. */
1817 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1818 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1819 overflow) and negate (which can't either). Special-case a result
1820 of zero while we're here. */
1826 else
1830 MINUS_EXPR,
1832 }
1833 \f
1834 /* A subroutine of fold_convert_const handling conversions of an
1835 INTEGER_CST to another integer type. */
1837 static tree
1839 {
1840 /* Given an integer constant, make new constant with new type,
1841 appropriately sign-extended or truncated. Use widest_int
1842 so that any extension is done according ARG1's type. */
1846 }
1848 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1849 to an integer type. */
1851 static tree
1853 {
1855 tree t;
1857 /* The following code implements the floating point to integer
1858 conversion rules required by the Java Language Specification,
1859 that IEEE NaNs are mapped to zero and values that overflow
1860 the target precision saturate, i.e. values greater than
1861 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1862 are mapped to INT_MIN. These semantics are allowed by the
1863 C and C++ standards that simply state that the behavior of
1864 FP-to-integer conversion is unspecified upon overflow. */
1866 wide_int val;
1867 REAL_VALUE_TYPE r;
1871 {
1878 }
1880 /* If R is NaN, return zero and show we have an overflow. */
1882 {
1885 }
1887 /* See if R is less than the lower bound or greater than the
1888 upper bound. */
1891 {
1895 {
1898 }
1899 }
1902 {
1905 {
1908 {
1911 }
1912 }
1913 }
1920 }
1922 /* A subroutine of fold_convert_const handling conversions of a
1923 FIXED_CST to an integer type. */
1925 static tree
1927 {
1928 tree t;
1932 /* Right shift FIXED_CST to temp by fbit. */
1936 {
1938 HOST_BITS_PER_DOUBLE_INT,
1941 /* Left shift temp to temp_trunc by fbit. */
1943 HOST_BITS_PER_DOUBLE_INT,
1945 }
1946 else
1947 {
1950 }
1952 /* If FIXED_CST is negative, we need to round the value toward 0.
1953 By checking if the fractional bits are not zero to add 1 to temp. */
1959 /* Given a fixed-point constant, make new constant with new type,
1960 appropriately sign-extended or truncated. */
1968 }
1970 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1971 to another floating point type. */
1973 static tree
1975 {
1976 REAL_VALUE_TYPE value;
1977 tree t;
1979 /* Don't perform the operation if flag_signaling_nans is on
1980 and the operand is a signaling NaN. */
1988 /* If converting an infinity or NAN to a representation that doesn't
1989 have one, set the overflow bit so that we can produce some kind of
1990 error message at the appropriate point if necessary. It's not the
1991 most user-friendly message, but it's better than nothing. */
1998 /* Regular overflow, conversion produced an infinity in a mode that
1999 can't represent them. */
2004 else
2007 }
2009 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2010 to a floating point type. */
2012 static tree
2014 {
2015 REAL_VALUE_TYPE value;
2016 tree t;
2023 }
2025 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2026 to another fixed-point type. */
2028 static tree
2030 {
2031 FIXED_VALUE_TYPE value;
2032 tree t;
2039 /* Propagate overflow flags. */
2043 }
2045 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2046 to a fixed-point type. */
2048 static tree
2050 {
2051 FIXED_VALUE_TYPE value;
2052 tree t;
2054 double_int di;
2061 else
2069 /* Propagate overflow flags. */
2073 }
2075 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2076 to a fixed-point type. */
2078 static tree
2080 {
2081 FIXED_VALUE_TYPE value;
2082 tree t;
2090 /* Propagate overflow flags. */
2094 }
2096 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2097 type TYPE. If no simplification can be done return NULL_TREE. */
2099 static tree
2101 {
2107 {
2114 }
2116 {
2123 }
2125 {
2132 }
2134 {
2137 {
2142 {
2148 }
2150 }
2151 }
2153 }
2155 /* Construct a vector of zero elements of vector type TYPE. */
2157 static tree
2159 {
2160 tree t;
2164 }
2166 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2168 bool
2170 {
2185 {
2200 }
2201 }
2203 /* Convert expression ARG to type TYPE. Used by the middle-end for
2204 simple conversions in preference to calling the front-end's convert. */
2206 tree
2208 {
2210 tree tem;
2221 {
2224 /* Handle conversions between pointers to different address spaces. */
2229 /* fall through */
2234 {
2238 }
2252 {
2256 }
2258 {
2262 }
2264 {
2268 }
2271 {
2289 }
2294 {
2298 }
2301 {
2315 }
2319 {
2328 integer_zero_node));
2330 {
2334 {
2340 }
2348 }
2352 }
2370 }
2371 fold_convert_exit:
2374 }
2375 \f
2376 /* Return false if expr can be assumed not to be an lvalue, true
2377 otherwise. */
2379 static bool
2381 {
2382 /* We only need to wrap lvalue tree codes. */
2384 {
2415 /* Assume the worst for front-end tree codes. */
2419 }
2422 }
2424 /* Return an expr equal to X but certainly not valid as an lvalue. */
2426 tree
2428 {
2429 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2430 us. */
2437 }
2439 /* When pedantic, return an expr equal to X but certainly not valid as a
2440 pedantic lvalue. Otherwise, return X. */
2442 static tree
2444 {
2446 }
2447 \f
2448 /* Given a tree comparison code, return the code that is the logical inverse.
2449 It is generally not safe to do this for floating-point comparisons, except
2450 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2451 ERROR_MARK in this case. */
2453 enum tree_code
2455 {
2461 {
2492 }
2493 }
2495 /* Similar, but return the comparison that results if the operands are
2496 swapped. This is safe for floating-point. */
2498 enum tree_code
2500 {
2502 {
2528 }
2529 }
2532 /* Convert a comparison tree code from an enum tree_code representation
2533 into a compcode bit-based encoding. This function is the inverse of
2534 compcode_to_comparison. */
2536 static enum comparison_code
2538 {
2540 {
2571 }
2572 }
2574 /* Convert a compcode bit-based encoding of a comparison operator back
2575 to GCC's enum tree_code representation. This function is the
2576 inverse of comparison_to_compcode. */
2578 static enum tree_code
2580 {
2582 {
2613 }
2614 }
2616 /* Return a tree for the comparison which is the combination of
2617 doing the AND or OR (depending on CODE) of the two operations LCODE
2618 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2619 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2620 if this makes the transformation invalid. */
2622 tree
2627 {
2634 {
2645 }
2648 {
2649 /* Eliminate unordered comparisons, as well as LTGT and ORD
2650 which are not used unless the mode has NaNs. */
2656 }
2658 {
2659 /* Check that the original operation and the optimized ones will trap
2660 under the same condition. */
2671 /* In a short-circuited boolean expression the LHS might be
2672 such that the RHS, if evaluated, will never trap. For
2673 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2674 if neither x nor y is NaN. (This is a mixed blessing: for
2675 example, the expression above will never trap, hence
2676 optimizing it to x < y would be invalid). */
2681 /* If the comparison was short-circuited, and only the RHS
2682 trapped, we may now generate a spurious trap. */
2687 /* If we changed the conditions that cause a trap, we lose. */
2690 }
2696 else
2697 {
2702 }
2703 }
2704 \f
2705 /* Return nonzero if two operands (typically of the same tree node)
2706 are necessarily equal. FLAGS modifies behavior as follows:
2708 If OEP_ONLY_CONST is set, only return nonzero for constants.
2709 This function tests whether the operands are indistinguishable;
2710 it does not test whether they are equal using C's == operation.
2711 The distinction is important for IEEE floating point, because
2712 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2713 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2715 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2716 even though it may hold multiple values during a function.
2717 This is because a GCC tree node guarantees that nothing else is
2718 executed between the evaluation of its "operands" (which may often
2719 be evaluated in arbitrary order). Hence if the operands themselves
2720 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2721 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2722 unset means assuming isochronic (or instantaneous) tree equivalence.
2723 Unless comparing arbitrary expression trees, such as from different
2724 statements, this flag can usually be left unset.
2726 If OEP_PURE_SAME is set, then pure functions with identical arguments
2727 are considered the same. It is used when the caller has other ways
2728 to ensure that global memory is unchanged in between.
2730 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2731 not values of expressions.
2733 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2734 any operand with side effect. This is unnecesarily conservative in the
2735 case we know that arg0 and arg1 are in disjoint code paths (such as in
2736 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2737 addresses with TREE_CONSTANT flag set so we know that &var == &var
2738 even if var is volatile. */
2740 int
2742 {
2743 /* When checking, verify at the outermost operand_equal_p call that
2744 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2745 hash value. */
2747 {
2749 {
2751 {
2758 }
2760 }
2761 else
2763 }
2765 /* If either is ERROR_MARK, they aren't equal. */
2771 /* Similar, if either does not have a type (like a released SSA name),
2772 they aren't equal. */
2776 /* We cannot consider pointers to different address space equal. */
2783 /* Check equality of integer constants before bailing out due to
2784 precision differences. */
2786 {
2787 /* Address of INTEGER_CST is not defined; check that we did not forget
2788 to drop the OEP_ADDRESS_OF flags. */
2791 }
2794 {
2795 /* If both types don't have the same signedness, then we can't consider
2796 them equal. We must check this before the STRIP_NOPS calls
2797 because they may change the signedness of the arguments. As pointers
2798 strictly don't have a signedness, require either two pointers or
2799 two non-pointers as well. */
2805 /* If both types don't have the same precision, then it is not safe
2806 to strip NOPs. */
2813 }
2814 #if 0
2815 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2816 sanity check once the issue is solved. */
2817 else
2818 /* Addresses of conversions and SSA_NAMEs (and many other things)
2819 are not defined. Check that we did not forget to drop the
2820 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2823 #endif
2825 /* In case both args are comparisons but with different comparison
2826 code, try to swap the comparison operands of one arg to produce
2827 a match and compare that variant. */
2831 {
2839 }
2842 {
2843 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2845 ;
2847 {
2848 /* If we are interested in comparing addresses ignore
2849 MEM_REF wrappings of the base that can appear just for
2850 TBAA reasons. */
2864 }
2865 else
2867 }
2869 /* When not checking adddresses, this is needed for conversions and for
2870 COMPONENT_REF. Might as well play it safe and always test this. */
2877 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2878 We don't care about side effects in that case because the SAVE_EXPR
2879 takes care of that for us. In all other cases, two expressions are
2880 equal if they have no side effects. If we have two identical
2881 expressions with side effects that should be treated the same due
2882 to the only side effects being identical SAVE_EXPR's, that will
2883 be detected in the recursive calls below.
2884 If we are taking an invariant address of two identical objects
2885 they are necessarily equal as well. */
2892 /* Next handle constant cases, those for which we can return 1 even
2893 if ONLY_CONST is set. */
2896 {
2910 {
2911 /* If we do not distinguish between signed and unsigned zero,
2912 consider them equal. */
2915 }
2919 {
2926 {
2930 }
2932 }
2936 flags)
2938 flags));
2949 flags | OEP_ADDRESS_OF
2952 /* In GIMPLE empty constructors are allowed in initializers of
2953 aggregates. */
2957 }
2962 /* Define macros to test an operand from arg0 and arg1 for equality and a
2963 variant that allows null and views null as being different from any
2964 non-null value. In the latter case, if either is null, the both
2965 must be; otherwise, do the normal comparison. */
2966 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2967 TREE_OPERAND (arg1, N), flags)
2969 #define OP_SAME_WITH_NULL(N) \
2970 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2971 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2974 {
2976 /* Two conversions are equal only if signedness and modes match. */
2978 {
2979 CASE_CONVERT:
2987 }
2997 /* For commutative ops, allow the other order. */
3005 /* If either of the pointer (or reference) expressions we are
3006 dereferencing contain a side effect, these cannot be equal,
3007 but their addresses can be. */
3014 {
3024 /* Require the same offset. */
3030 /* Fallthru. */
3038 {
3039 /* Require equal access sizes */
3045 flags)))
3047 /* Verify that access happens in similar types. */
3050 /* Verify that accesses are TBAA compatible. */
3059 /* Verify that alignment is compatible. */
3063 }
3066 /* TARGET_MEM_REF require equal extra operands. */
3077 /* Compare the array index by value if it is constant first as we
3078 may have different types but same value here. */
3084 /* Compare low bound and element size as with OEP_ADDRESS_OF
3085 we have to account for the offset of the ref. */
3090 array_ref_low_bound
3094 array_ref_element_size
3096 flags))));
3099 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3100 may be NULL when we're called to compare MEM_EXPRs. */
3115 }
3119 {
3121 /* Be sure we pass right ADDRESS_OF flag. */
3139 /* The multiplcation operands are commutative. */
3140 /* FALLTHRU */
3148 /* Otherwise take into account this is a commutative operation. */
3167 }
3171 {
3175 /* If not both CALL_EXPRs are either internal or normal function
3176 functions, then they are not equal. */
3179 {
3180 /* If the CALL_EXPRs call different internal functions, then they
3181 are not equal. */
3184 }
3185 else
3186 {
3187 /* If the CALL_EXPRs call different functions, then they are not
3188 equal. */
3190 flags))
3192 }
3194 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3195 {
3199 else
3203 }
3205 /* Now see if all the arguments are the same. */
3206 {
3217 /* If we get here and both argument lists are exhausted
3218 then the CALL_EXPRs are equal. */
3220 }
3223 }
3226 /* Consider __builtin_sqrt equal to sqrt. */
3234 {
3235 /* In GIMPLE constructors are used only to build vectors from
3236 elements. Individual elements in the constructor must be
3237 indexed in increasing order and form an initial sequence.
3239 We make no effort to compare constructors in generic.
3240 (see sem_variable::equals in ipa-icf which can do so for
3241 constants). */
3246 /* Be sure that vectors constructed have the same representation.
3247 We only tested element precision and modes to match.
3248 Vectors may be BLKmode and thus also check that the number of
3249 parts match. */
3262 {
3267 /* In GIMPLE the indexes can be either NULL or matching i.
3268 Double check this so we won't get false
3269 positives for GENERIC. */
3277 }
3279 }
3284 }
3286 #undef OP_SAME
3287 #undef OP_SAME_WITH_NULL
3288 }
3289 \f
3290 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3291 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3293 When in doubt, return 0. */
3295 static int
3297 {
3309 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3310 and see if the inner values are the same. This removes any
3311 signedness comparison, which doesn't matter here. */
3318 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3319 actual comparison operand, ARG0.
3321 First throw away any conversions to wider types
3322 already present in the operands. */
3331 {
3334 /* Make sure shorter operand is extended the right way
3335 to match the longer operand. */
3341 }
3344 }
3345 \f
3346 /* See if ARG is an expression that is either a comparison or is performing
3347 arithmetic on comparisons. The comparisons must only be comparing
3348 two different values, which will be stored in *CVAL1 and *CVAL2; if
3349 they are nonzero it means that some operands have already been found.
3350 No variables may be used anywhere else in the expression except in the
3351 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3352 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3354 If this is true, return 1. Otherwise, return zero. */
3356 static int
3358 {
3362 /* We can handle some of the tcc_expression cases here. */
3372 {
3373 /* If we've already found a CVAL1 or CVAL2, this expression is
3374 two complex to handle. */
3380 }
3383 {
3406 /* First see if we can handle the first operand, then the second. For
3407 the second operand, we know *CVAL1 can't be zero. It must be that
3408 one side of the comparison is each of the values; test for the
3409 case where this isn't true by failing if the two operands
3410 are the same. */
3419 ;
3423 ;
3424 else
3428 ;
3432 ;
3433 else
3440 }
3441 }
3442 \f
3443 /* ARG is a tree that is known to contain just arithmetic operations and
3444 comparisons. Evaluate the operations in the tree substituting NEW0 for
3445 any occurrence of OLD0 as an operand of a comparison and likewise for
3446 NEW1 and OLD1. */
3448 static tree
3451 {
3456 /* We can handle some of the tcc_expression cases here. */
3464 {
3479 {
3498 }
3499 /* Fall through - ??? */
3502 {
3506 /* We need to check both for exact equality and tree equality. The
3507 former will be true if the operand has a side-effect. In that
3508 case, we know the operand occurred exactly once. */
3521 }
3525 }
3526 }
3527 \f
3528 /* Return a tree for the case when the result of an expression is RESULT
3529 converted to TYPE and OMITTED was previously an operand of the expression
3530 but is now not needed (e.g., we folded OMITTED * 0).
3532 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3533 the conversion of RESULT to TYPE. */
3535 tree
3537 {
3540 /* If the resulting operand is an empty statement, just return the omitted
3541 statement casted to void. */
3551 }
3553 /* Return a tree for the case when the result of an expression is RESULT
3554 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3555 of the expression but are now not needed.
3557 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3558 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3559 evaluated before OMITTED2. Otherwise, if neither has side effects,
3560 just do the conversion of RESULT to TYPE. */
3562 tree
3565 {
3574 }
3576 \f
3577 /* Return a simplified tree node for the truth-negation of ARG. This
3578 never alters ARG itself. We assume that ARG is an operation that
3579 returns a truth value (0 or 1).
3581 FIXME: one would think we would fold the result, but it causes
3582 problems with the dominator optimizer. */
3584 static tree
3586 {
3591 /* If this is a comparison, we can simply invert it, except for
3592 floating-point non-equality comparisons, in which case we just
3593 enclose a TRUTH_NOT_EXPR around what we have. */
3596 {
3599 && flag_trapping_math
3613 }
3616 {
3635 /* Here we can invert either operand. We invert the first operand
3636 unless the second operand is a TRUTH_NOT_EXPR in which case our
3637 result is the XOR of the first operand with the inside of the
3638 negation of the second operand. */
3643 else
3666 {
3673 /* A COND_EXPR may have a throw as one operand, which
3674 then has void type. Just leave void operands
3675 as they are. */
3681 }
3693 CASE_CONVERT:
3697 /* fall through */
3719 }
3720 }
3722 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3723 assume that ARG is an operation that returns a truth value (0 or 1
3724 for scalars, 0 or -1 for vectors). Return the folded expression if
3725 folding is successful. Otherwise, return NULL_TREE. */
3727 static tree
3729 {
3732 ? BIT_NOT_EXPR
3735 }
3737 /* Return a simplified tree node for the truth-negation of ARG. This
3738 never alters ARG itself. We assume that ARG is an operation that
3739 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3741 tree
3743 {
3749 ? BIT_NOT_EXPR
3752 }
3754 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3755 with code CODE. This optimization is unsafe. */
3756 static tree
3759 {
3763 /* (A / C) +- (B / C) -> (A +- B) / C. */
3773 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3778 {
3790 }
3793 }
3794 \f
3795 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3796 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3797 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3798 is the original memory reference used to preserve the alias set of
3799 the access. */
3801 static tree
3805 {
3815 {
3822 }
3837 }
3839 /* Optimize a bit-field compare.
3841 There are two cases: First is a compare against a constant and the
3842 second is a comparison of two items where the fields are at the same
3843 bit position relative to the start of a chunk (byte, halfword, word)
3844 large enough to contain it. In these cases we can avoid the shift
3845 implicit in bitfield extractions.
3847 For constants, we emit a compare of the shifted constant with the
3848 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3849 compared. For two fields at the same position, we do the ANDs with the
3850 similar mask and compare the result of the ANDs.
3852 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3853 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3854 are the left and right operands of the comparison, respectively.
3856 If the optimization described above can be done, we return the resulting
3857 tree. Otherwise we return zero. */
3859 static tree
3862 {
3865 tree unsigned_type;
3872 tree mask;
3873 tree offset;
3875 /* Get all the information about the extractions being done. If the bit size
3876 if the same as the size of the underlying object, we aren't doing an
3877 extraction at all and so can do nothing. We also don't want to
3878 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3879 then will no longer be able to replace it. */
3888 else
3889 {
3890 /* If this is not a constant, we can only do something if bit positions,
3891 sizes, signedness and storage order are the same. */
3892 rinner
3900 }
3902 /* Honor the C++ memory model and mimic what RTL expansion does. */
3906 {
3910 }
3912 /* See if we can find a mode to refer to this field. We should be able to,
3913 but fail if we can't. */
3922 /* Set signed and unsigned types of the precision of this mode for the
3923 shifts below. */
3926 /* Compute the bit position and size for the new reference and our offset
3927 within it. If the new reference is the same size as the original, we
3928 won't optimize anything, so return zero. */
3938 /* Make the mask to be used against the extracted field. */
3945 /* If not comparing with constant, just rework the comparison
3946 and return. */
3950 unsigned_type,
3953 mask),
3956 unsigned_type,
3959 mask));
3961 /* Otherwise, we are handling the constant case. See if the constant is too
3962 big for the field. Warn and return a tree for 0 (false) if so. We do
3963 this not only for its own sake, but to avoid having to test for this
3964 error case below. If we didn't, we might generate wrong code.
3966 For unsigned fields, the constant shifted right by the field length should
3967 be all zero. For signed fields, the high-order bits should agree with
3968 the sign bit. */
3971 {
3973 {
3977 }
3978 }
3979 else
3980 {
3983 {
3987 }
3988 }
3990 /* Single-bit compares should always be against zero. */
3992 {
3995 }
3997 /* Make a new bitfield reference, shift the constant over the
3998 appropriate number of bits and mask it with the computed mask
3999 (in case this was a signed field). If we changed it, make a new one. */
4007 mask);
4012 }
4013 \f
4014 /* Subroutine for fold_truth_andor_1: decode a field reference.
4016 If EXP is a comparison reference, we return the innermost reference.
4018 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4019 set to the starting bit number.
4021 If the innermost field can be completely contained in a mode-sized
4022 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4024 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4025 otherwise it is not changed.
4027 *PUNSIGNEDP is set to the signedness of the field.
4029 *PREVERSEP is set to the storage order of the field.
4031 *PMASK is set to the mask used. This is either contained in a
4032 BIT_AND_EXPR or derived from the width of the field.
4034 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4036 Return 0 if this is not a component reference or is one that we can't
4037 do anything with. */
4039 static tree
4044 {
4049 tree unsigned_type;
4052 /* All the optimizations using this function assume integer fields.
4053 There are problems with FP fields since the type_for_size call
4054 below can fail for, e.g., XFmode. */
4058 /* We are interested in the bare arrangement of bits, so strip everything
4059 that doesn't affect the machine mode. However, record the type of the
4060 outermost expression if it may matter below. */
4067 {
4073 }
4084 /* If the number of bits in the reference is the same as the bitsize of
4085 the outer type, then the outer type gives the signedness. Otherwise
4086 (in case of a small bitfield) the signedness is unchanged. */
4090 /* Compute the mask to access the bitfield. */
4099 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4107 }
4109 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4110 bit positions and MASK is SIGNED. */
4112 static int
4114 {
4118 /* If this function returns true when the type of the mask is
4119 UNSIGNED, then there will be errors. In particular see
4120 gcc.c-torture/execute/990326-1.c. There does not appear to be
4121 any documentation paper trail as to why this is so. But the pre
4122 wide-int worked with that restriction and it has been preserved
4123 here. */
4128 }
4130 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4131 represents the sign bit of EXP's type. If EXP represents a sign
4132 or zero extension, also test VAL against the unextended type.
4133 The return value is the (sub)expression whose sign bit is VAL,
4134 or NULL_TREE otherwise. */
4136 tree
4138 {
4140 tree t;
4142 /* Tree EXP must have an integral type. */
4147 /* Tree VAL must be an integer constant. */
4156 /* Handle extension from a narrower type. */
4162 }
4164 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4165 to be evaluated unconditionally. */
4167 static int
4169 {
4170 /* Strip any conversions that don't change the machine mode. */
4179 /* Don't regard global variables as simple. They may be
4180 allocated in ways unknown to the compiler (shared memory,
4181 #pragma weak, etc). */
4184 /* Weakrefs are not safe to be read, since they can be NULL.
4185 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4186 have DECL_WEAK flag set. */
4188 /* Loading a static variable is unduly expensive, but global
4189 registers aren't expensive. */
4191 }
4193 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4194 to be evaluated unconditionally.
4195 I addition to simple_operand_p, we assume that comparisons, conversions,
4196 and logic-not operations are simple, if their operands are simple, too. */
4198 static bool
4200 {
4220 }
4222 \f
4223 /* The following functions are subroutines to fold_range_test and allow it to
4224 try to change a logical combination of comparisons into a range test.
4226 For example, both
4227 X == 2 || X == 3 || X == 4 || X == 5
4228 and
4229 X >= 2 && X <= 5
4230 are converted to
4231 (unsigned) (X - 2) <= 3
4233 We describe each set of comparisons as being either inside or outside
4234 a range, using a variable named like IN_P, and then describe the
4235 range with a lower and upper bound. If one of the bounds is omitted,
4236 it represents either the highest or lowest value of the type.
4238 In the comments below, we represent a range by two numbers in brackets
4239 preceded by a "+" to designate being inside that range, or a "-" to
4240 designate being outside that range, so the condition can be inverted by
4241 flipping the prefix. An omitted bound is represented by a "-". For
4242 example, "- [-, 10]" means being outside the range starting at the lowest
4243 possible value and ending at 10, in other words, being greater than 10.
4244 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4245 always false.
4247 We set up things so that the missing bounds are handled in a consistent
4248 manner so neither a missing bound nor "true" and "false" need to be
4249 handled using a special case. */
4251 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4252 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4253 and UPPER1_P are nonzero if the respective argument is an upper bound
4254 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4255 must be specified for a comparison. ARG1 will be converted to ARG0's
4256 type if both are specified. */
4258 static tree
4261 {
4262 tree tem;
4266 /* If neither arg represents infinity, do the normal operation.
4267 Else, if not a comparison, return infinity. Else handle the special
4268 comparison rules. Note that most of the cases below won't occur, but
4269 are handled for consistency. */
4272 {
4277 }
4282 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4283 for neither. In real maths, we cannot assume open ended ranges are
4284 the same. But, this is computer arithmetic, where numbers are finite.
4285 We can therefore make the transformation of any unbounded range with
4286 the value Z, Z being greater than any representable number. This permits
4287 us to treat unbounded ranges as equal. */
4291 {
4312 }
4315 }
4316 \f
4317 /* Helper routine for make_range. Perform one step for it, return
4318 new expression if the loop should continue or NULL_TREE if it should
4319 stop. */
4321 tree
4325 {
4331 {
4333 /* We can only do something if the range is testing for zero. */
4342 /* We can only do something if the range is testing for zero
4343 and if the second operand is an integer constant. Note that
4344 saying something is "in" the range we make is done by
4345 complementing IN_P since it will set in the initial case of
4346 being not equal to zero; "out" is leaving it alone. */
4353 {
4374 }
4376 /* If this is an unsigned comparison, we also know that EXP is
4377 greater than or equal to zero. We base the range tests we make
4378 on that fact, so we record it here so we can parse existing
4379 range tests. We test arg0_type since often the return type
4380 of, e.g. EQ_EXPR, is boolean. */
4382 {
4386 NULL_TREE))
4391 /* If the high bound is missing, but we have a nonzero low
4392 bound, reverse the range so it goes from zero to the low bound
4393 minus 1. */
4395 {
4400 }
4401 }
4409 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4410 low and high are non-NULL, then normalize will DTRT. */
4413 {
4418 }
4420 /* (-x) IN [a,b] -> x in [-b, -a] */
4432 /* ~ X -> -X - 1 */
4441 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4442 move a constant to the other side. */
4447 /* If EXP is signed, any overflow in the computation is undefined,
4448 so we don't worry about it so long as our computations on
4449 the bounds don't overflow. For unsigned, overflow is defined
4450 and this is exactly the right thing. */
4462 normalize:
4463 /* Check for an unsigned range which has wrapped around the maximum
4464 value thus making n_high < n_low, and normalize it. */
4466 {
4472 /* If the range is of the form +/- [ x+1, x ], we won't
4473 be able to normalize it. But then, it represents the
4474 whole range or the empty set, so make it
4475 +/- [ -, - ]. */
4479 else
4481 }
4482 else
4490 CASE_CONVERT:
4508 /* If we're converting arg0 from an unsigned type, to exp,
4509 a signed type, we will be doing the comparison as unsigned.
4510 The tests above have already verified that LOW and HIGH
4511 are both positive.
4513 So we have to ensure that we will handle large unsigned
4514 values the same way that the current signed bounds treat
4515 negative values. */
4518 {
4519 tree high_positive;
4520 tree equiv_type;
4521 /* For fixed-point modes, we need to pass the saturating flag
4522 as the 2nd parameter. */
4524 equiv_type
4527 else
4528 equiv_type
4531 /* A range without an upper bound is, naturally, unbounded.
4532 Since convert would have cropped a very large value, use
4533 the max value for the destination type. */
4534 high_positive
4541 high_positive),
4544 /* If the low bound is specified, "and" the range with the
4545 range for which the original unsigned value will be
4546 positive. */
4548 {
4551 integer_zero_node),
4552 high_positive))
4556 }
4557 else
4558 {
4559 /* Otherwise, "or" the range with the range of the input
4560 that will be interpreted as negative. */
4563 integer_zero_node),
4564 high_positive))
4568 }
4569 }
4578 }
4579 }
4581 /* Given EXP, a logical expression, set the range it is testing into
4582 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4583 actually being tested. *PLOW and *PHIGH will be made of the same
4584 type as the returned expression. If EXP is not a comparison, we
4585 will most likely not be returning a useful value and range. Set
4586 *STRICT_OVERFLOW_P to true if the return value is only valid
4587 because signed overflow is undefined; otherwise, do not change
4588 *STRICT_OVERFLOW_P. */
4590 tree
4593 {
4601 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4602 and see if we can refine the range. Some of the cases below may not
4603 happen, but it doesn't seem worth worrying about this. We "continue"
4604 the outer loop when we've changed something; otherwise we "break"
4605 the switch, which will "break" the while. */
4611 {
4617 {
4625 }
4634 }
4636 /* If EXP is a constant, we can evaluate whether this is true or false. */
4638 {
4645 }
4649 }
4650 \f
4651 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4652 type, TYPE, return an expression to test if EXP is in (or out of, depending
4653 on IN_P) the range. Return 0 if the test couldn't be created. */
4655 tree
4658 {
4661 /* Disable this optimization for function pointer expressions
4662 on targets that require function pointer canonicalization. */
4669 {
4675 }
4693 {
4695 {
4699 }
4701 }
4703 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4705 {
4709 {
4711 {
4714 etype
4716 else
4719 }
4722 }
4723 }
4725 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4726 This requires wrap-around arithmetics for the type of the expression.
4727 First make sure that arithmetics in this type is valid, then make sure
4728 that it wraps around. */
4734 {
4737 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4738 for the type in question, as we rely on this here. */
4748 else
4750 }
4760 {
4762 {
4767 }
4769 }
4777 }
4778 \f
4779 /* Return the predecessor of VAL in its type, handling the infinite case. */
4781 static tree
4783 {
4789 else
4792 }
4794 /* Return the successor of VAL in its type, handling the infinite case. */
4796 static tree
4798 {
4804 else
4807 }
4809 /* Given two ranges, see if we can merge them into one. Return 1 if we
4810 can, 0 if we can't. Set the output range into the specified parameters. */
4812 bool
4815 {
4819 tree tem;
4829 /* Make range 0 be the range that starts first, or ends last if they
4830 start at the same value. Swap them if it isn't. */
4833 || (lowequal
4836 {
4840 }
4842 /* Now flag two cases, whether the ranges are disjoint or whether the
4843 second range is totally subsumed in the first. Note that the tests
4844 below are simplified by the ones above. */
4850 /* We now have four cases, depending on whether we are including or
4851 excluding the two ranges. */
4853 {
4854 /* If they don't overlap, the result is false. If the second range
4855 is a subset it is the result. Otherwise, the range is from the start
4856 of the second to the end of the first. */
4861 else
4863 }
4866 {
4867 /* If they don't overlap, the result is the first range. If they are
4868 equal, the result is false. If the second range is a subset of the
4869 first, and the ranges begin at the same place, we go from just after
4870 the end of the second range to the end of the first. If the second
4871 range is not a subset of the first, or if it is a subset and both
4872 ranges end at the same place, the range starts at the start of the
4873 first range and ends just before the second range.
4874 Otherwise, we can't describe this as a single range. */
4880 {
4885 {
4886 /* We are in the weird situation where high0 > high1 but
4887 high1 has no successor. Punt. */
4889 }
4890 }
4892 {
4897 {
4898 /* low0 < low1 but low1 has no predecessor. Punt. */
4900 }
4901 }
4902 else
4904 }
4907 {
4908 /* If they don't overlap, the result is the second range. If the second
4909 is a subset of the first, the result is false. Otherwise,
4910 the range starts just after the first range and ends at the
4911 end of the second. */
4916 else
4917 {
4922 {
4923 /* high1 > high0 but high0 has no successor. Punt. */
4925 }
4926 }
4927 }
4929 else
4930 {
4931 /* The case where we are excluding both ranges. Here the complex case
4932 is if they don't overlap. In that case, the only time we have a
4933 range is if they are adjacent. If the second is a subset of the
4934 first, the result is the first. Otherwise, the range to exclude
4935 starts at the beginning of the first range and ends at the end of the
4936 second. */
4938 {
4943 else
4944 {
4945 /* Canonicalize - [min, x] into - [-, x]. */
4948 {
4953 /* FALLTHROUGH */
4966 }
4968 /* Canonicalize - [x, max] into - [x, -]. */
4971 {
4976 /* FALLTHROUGH */
4992 }
4994 /* The ranges might be also adjacent between the maximum and
4995 minimum values of the given type. For
4996 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4997 return + [x + 1, y - 1]. */
4999 {
5006 }
5007 else
5009 }
5010 }
5013 else
5015 }
5019 }
5020 \f
5022 /* Subroutine of fold, looking inside expressions of the form
5023 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5024 of the COND_EXPR. This function is being used also to optimize
5025 A op B ? C : A, by reversing the comparison first.
5027 Return a folded expression whose code is not a COND_EXPR
5028 anymore, or NULL_TREE if no folding opportunity is found. */
5030 static tree
5033 {
5038 tree tem;
5043 /* If we have A op 0 ? A : -A, consider applying the following
5044 transformations:
5046 A == 0? A : -A same as -A
5047 A != 0? A : -A same as A
5048 A >= 0? A : -A same as abs (A)
5049 A > 0? A : -A same as abs (A)
5050 A <= 0? A : -A same as -abs (A)
5051 A < 0? A : -A same as -abs (A)
5053 None of these transformations work for modes with signed
5054 zeros. If A is +/-0, the first two transformations will
5055 change the sign of the result (from +0 to -0, or vice
5056 versa). The last four will fix the sign of the result,
5057 even though the original expressions could be positive or
5058 negative, depending on the sign of A.
5060 Note that all these transformations are correct if A is
5061 NaN, since the two alternatives (A and -A) are also NaNs. */
5068 /* In the case that A is of the form X-Y, '-A' (arg2) may
5069 have already been folded to Y-X, check for that. */
5077 {
5089 /* Fall through. */
5100 /* FALLTHRU */
5110 }
5112 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5113 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5114 both transformations are correct when A is NaN: A != 0
5115 is then true, and A == 0 is false. */
5119 {
5124 }
5126 /* Try some transformations of A op B ? A : B.
5128 A == B? A : B same as B
5129 A != B? A : B same as A
5130 A >= B? A : B same as max (A, B)
5131 A > B? A : B same as max (B, A)
5132 A <= B? A : B same as min (A, B)
5133 A < B? A : B same as min (B, A)
5135 As above, these transformations don't work in the presence
5136 of signed zeros. For example, if A and B are zeros of
5137 opposite sign, the first two transformations will change
5138 the sign of the result. In the last four, the original
5139 expressions give different results for (A=+0, B=-0) and
5140 (A=-0, B=+0), but the transformed expressions do not.
5142 The first two transformations are correct if either A or B
5143 is a NaN. In the first transformation, the condition will
5144 be false, and B will indeed be chosen. In the case of the
5145 second transformation, the condition A != B will be true,
5146 and A will be chosen.
5148 The conversions to max() and min() are not correct if B is
5149 a number and A is not. The conditions in the original
5150 expressions will be false, so all four give B. The min()
5151 and max() versions would give a NaN instead. */
5154 /* Avoid these transformations if the COND_EXPR may be used
5155 as an lvalue in the C++ front-end. PR c++/19199. */
5156 && (in_gimple_form
5162 {
5168 {
5177 /* In C++ a ?: expression can be an lvalue, so put the
5178 operand which will be used if they are equal first
5179 so that we can convert this back to the
5180 corresponding COND_EXPR. */
5182 {
5190 }
5197 {
5205 }
5218 }
5219 }
5221 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5222 we might still be able to simplify this. For example,
5223 if C1 is one less or one more than C2, this might have started
5224 out as a MIN or MAX and been transformed by this function.
5225 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5231 {
5235 /* We can replace A with C1 in this case. */
5240 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5241 MIN_EXPR, to preserve the signedness of the comparison. */
5243 OEP_ONLY_CONST)
5247 OEP_ONLY_CONST))
5248 {
5251 arg2));
5253 }
5257 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5258 as above. */
5260 OEP_ONLY_CONST)
5264 OEP_ONLY_CONST))
5265 {
5268 arg2));
5270 }
5274 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5275 MAX_EXPR, to preserve the signedness of the comparison. */
5277 OEP_ONLY_CONST)
5281 OEP_ONLY_CONST))
5282 {
5285 arg2));
5287 }
5291 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5293 OEP_ONLY_CONST)
5297 OEP_ONLY_CONST))
5298 {
5301 arg2));
5303 }
5309 }
5312 }
5315 \f
5316 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5317 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5318 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5319 false) >= 2)
5320 #endif
5322 /* EXP is some logical combination of boolean tests. See if we can
5323 merge it into some range test. Return the new tree if so. */
5325 static tree
5328 {
5344 /* If this is an OR operation, invert both sides; we will invert
5345 again at the end. */
5349 /* If both expressions are the same, if we can merge the ranges, and we
5350 can build the range test, return it or it inverted. If one of the
5351 ranges is always true or always false, consider it to be the same
5352 expression as the other. */
5360 {
5364 }
5366 /* On machines where the branch cost is expensive, if this is a
5367 short-circuited branch and the underlying object on both sides
5368 is the same, make a non-short-circuit operation. */
5374 {
5375 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5376 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5377 which cases we can't do this. */
5385 {
5394 {
5397 WARN_STRICT_OVERFLOW_COMPARISON);
5401 }
5402 }
5403 }
5406 }
5407 \f
5408 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5409 bit value. Arrange things so the extra bits will be set to zero if and
5410 only if C is signed-extended to its full width. If MASK is nonzero,
5411 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5413 static tree
5415 {
5418 tree temp;
5423 /* We work by getting just the sign bit into the low-order bit, then
5424 into the high-order bit, then sign-extend. We then XOR that value
5425 with C. */
5428 /* We must use a signed type in order to get an arithmetic right shift.
5429 However, we must also avoid introducing accidental overflows, so that
5430 a subsequent call to integer_zerop will work. Hence we must
5431 do the type conversion here. At this point, the constant is either
5432 zero or one, and the conversion to a signed type can never overflow.
5433 We could get an overflow if this conversion is done anywhere else. */
5442 /* If necessary, convert the type back to match the type of C. */
5447 }
5448 \f
5449 /* For an expression that has the form
5450 (A && B) || ~B
5451 or
5452 (A || B) && ~B,
5453 we can drop one of the inner expressions and simplify to
5454 A || ~B
5455 or
5456 A && ~B
5457 LOC is the location of the resulting expression. OP is the inner
5458 logical operation; the left-hand side in the examples above, while CMPOP
5459 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5460 removing a condition that guards another, as in
5461 (A != NULL && A->...) || A == NULL
5462 which we must not transform. If RHS_ONLY is true, only eliminate the
5463 right-most operand of the inner logical operation. */
5465 static tree
5468 {
5486 {
5489 {
5492 }
5493 }
5495 {
5498 {
5501 }
5502 }
5517 }
5519 /* Find ways of folding logical expressions of LHS and RHS:
5520 Try to merge two comparisons to the same innermost item.
5521 Look for range tests like "ch >= '0' && ch <= '9'".
5522 Look for combinations of simple terms on machines with expensive branches
5523 and evaluate the RHS unconditionally.
5525 For example, if we have p->a == 2 && p->b == 4 and we can make an
5526 object large enough to span both A and B, we can do this with a comparison
5527 against the object ANDed with the a mask.
5529 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5530 operations to do this with one comparison.
5532 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5533 function and the one above.
5535 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5536 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5538 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5539 two operands.
5541 We return the simplified tree or 0 if no optimization is possible. */
5543 static tree
5546 {
5547 /* If this is the "or" of two comparisons, we can do something if
5548 the comparisons are NE_EXPR. If this is the "and", we can do something
5549 if the comparisons are EQ_EXPR. I.e.,
5550 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5552 WANTED_CODE is this operation code. For single bit fields, we can
5553 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5554 comparison for one-bit fields. */
5575 /* Start by getting the comparison codes. Fail if anything is volatile.
5576 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5577 it were surrounded with a NE_EXPR. */
5586 {
5590 }
5593 {
5597 }
5608 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5611 {
5614 {
5619 }
5622 {
5628 }
5629 }
5634 /* If the RHS can be evaluated unconditionally and its operands are
5635 simple, it wins to evaluate the RHS unconditionally on machines
5636 with expensive branches. In this case, this isn't a comparison
5637 that can be merged. */
5644 {
5645 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5656 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5666 }
5668 /* See if the comparisons can be merged. Then get all the parameters for
5669 each side. */
5694 /* It must be true that the inner operation on the lhs of each
5695 comparison must be the same if we are to be able to do anything.
5696 Then see if we have constants. If not, the same must be true for
5697 the rhs's. */
5706 {
5709 }
5714 else
5717 /* If either comparison code is not correct for our logical operation,
5718 fail. However, we can convert a one-bit comparison against zero into
5719 the opposite comparison against that bit being set in the field. */
5723 {
5725 {
5726 /* Make the left operand unsigned, since we are only interested
5727 in the value of one bit. Otherwise we are doing the wrong
5728 thing below. */
5731 }
5732 else
5734 }
5736 /* This is analogous to the code for l_const above. */
5738 {
5740 {
5743 }
5744 else
5746 }
5748 /* See if we can find a mode that contains both fields being compared on
5749 the left. If we can't, fail. Otherwise, update all constants and masks
5750 to be relative to a field of that size. */
5755 volatilep);
5765 {
5768 }
5776 {
5783 {
5787 }
5788 }
5790 {
5797 {
5801 }
5802 }
5804 /* If the right sides are not constant, do the same for it. Also,
5805 disallow this optimization if a size or signedness mismatch occurs
5806 between the left and right sides. */
5808 {
5811 /* Make sure the two fields on the right
5812 correspond to the left without being swapped. */
5820 volatilep);
5830 {
5833 }
5842 /* Make a mask that corresponds to both fields being compared.
5843 Do this for both items being compared. If the operands are the
5844 same size and the bits being compared are in the same position
5845 then we can do this by masking both and comparing the masked
5846 results. */
5850 {
5864 }
5866 /* There is still another way we can do something: If both pairs of
5867 fields being compared are adjacent, we may be able to make a wider
5868 field containing them both.
5870 Note that we still must mask the lhs/rhs expressions. Furthermore,
5871 the mask must be shifted to account for the shift done by
5872 make_bit_field_ref. */
5877 {
5878 tree type;
5894 /* Convert to the smaller type before masking out unwanted bits. */
5897 {
5899 {
5903 }
5905 {
5909 }
5910 }
5919 }
5922 }
5924 /* Handle the case of comparisons with constants. If there is something in
5925 common between the masks, those bits of the constants must be the same.
5926 If not, the condition is always false. Test for this to avoid generating
5927 incorrect code below. */
5932 {
5934 {
5937 }
5938 else
5939 {
5942 }
5943 }
5945 /* Construct the expression we will return. First get the component
5946 reference we will make. Unless the mask is all ones the width of
5947 that field, perform the mask operation. Then compare with the
5948 merged constant. */
5959 }
5960 \f
5961 /* T is an integer expression that is being multiplied, divided, or taken a
5962 modulus (CODE says which and what kind of divide or modulus) by a
5963 constant C. See if we can eliminate that operation by folding it with
5964 other operations already in T. WIDE_TYPE, if non-null, is a type that
5965 should be used for the computation if wider than our type.
5967 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5968 (X * 2) + (Y * 4). We must, however, be assured that either the original
5969 expression would not overflow or that overflow is undefined for the type
5970 in the language in question.
5972 If we return a non-null expression, it is an equivalent form of the
5973 original computation, but need not be in the original type.
5975 We set *STRICT_OVERFLOW_P to true if the return values depends on
5976 signed overflow being undefined. Otherwise we do not change
5977 *STRICT_OVERFLOW_P. */
5979 static tree
5982 {
5983 /* To avoid exponential search depth, refuse to allow recursion past
5984 three levels. Beyond that (1) it's highly unlikely that we'll find
5985 something interesting and (2) we've probably processed it before
5986 when we built the inner expression. */
5989 tree ret;
5994 depth++;
5996 depth--;
5999 }
6001 static tree
6004 {
6015 /* Don't deal with constants of zero here; they confuse the code below. */
6025 /* Note that we need not handle conditional operations here since fold
6026 already handles those cases. So just do arithmetic here. */
6028 {
6030 /* For a constant, we can always simplify if we are a multiply
6031 or (for divide and modulus) if it is a multiple of our constant. */
6034 {
6037 /* If the multiplication overflowed, we lost information on it.
6038 See PR68142 and PR69845. */
6042 }
6046 /* If op0 is an expression ... */
6052 /* ... and has wrapping overflow, and its type is smaller
6053 than ctype, then we cannot pass through as widening. */
6058 /* ... or this is a truncation (t is narrower than op0),
6059 then we cannot pass through this narrowing. */
6062 /* ... or signedness changes for division or modulus,
6063 then we cannot pass through this conversion. */
6067 /* ... or has undefined overflow while the converted to
6068 type has not, we cannot do the operation in the inner type
6069 as that would introduce undefined overflow. */
6075 /* Pass the constant down and see if we can make a simplification. If
6076 we can, replace this expression with the inner simplification for
6077 possible later conversion to our or some other type. */
6082 code == MULT_EXPR
6084 strict_overflow_p))))
6089 /* If widening the type changes it from signed to unsigned, then we
6090 must avoid building ABS_EXPR itself as unsigned. */
6092 {
6096 {
6099 }
6101 }
6102 /* If the constant is negative, we cannot simplify this. */
6105 /* FALLTHROUGH */
6107 /* For division and modulus, type can't be unsigned, as e.g.
6108 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6109 For signed types, even with wrapping overflow, this is fine. */
6118 /* If widening the type changes the signedness, then we can't perform
6119 this optimization as that changes the result. */
6123 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6129 {
6136 }
6140 /* If the second operand is constant, this is a multiplication
6141 or floor division, by a power of two, so we can treat it that
6142 way unless the multiplier or divisor overflows. Signed
6143 left-shift overflow is implementation-defined rather than
6144 undefined in C90, so do not convert signed left shift into
6145 multiplication. */
6148 /* const_binop may not detect overflow correctly,
6149 so check for it explicitly here. */
6153 size_one_node,
6154 op1)))
6158 ctype,
6160 t1),
6165 /* See if we can eliminate the operation on both sides. If we can, we
6166 can return a new PLUS or MINUS. If we can't, the only remaining
6167 cases where we can do anything are if the second operand is a
6168 constant. */
6174 /* If not multiplication, we can only do this if both operands
6175 are divisible by c. */
6178 {
6183 }
6185 /* If this was a subtraction, negate OP1 and set it to be an addition.
6186 This simplifies the logic below. */
6188 {
6190 /* If OP1 was not easily negatable, the constant may be OP0. */
6192 {
6195 }
6196 }
6201 /* If either OP1 or C are negative, this optimization is not safe for
6202 some of the division and remainder types while for others we need
6203 to change the code. */
6205 {
6213 }
6215 /* If it's a multiply or a division/modulus operation of a multiple
6216 of our constant, do the operation and verify it doesn't overflow. */
6219 {
6222 /* We allow the constant to overflow with wrapping semantics. */
6226 }
6227 else
6230 /* If we have an unsigned type, we cannot widen the operation since it
6231 will change the result if the original computation overflowed. */
6235 /* If we were able to eliminate our operation from the first side,
6236 apply our operation to the second side and reform the PLUS. */
6240 /* The last case is if we are a multiply. In that case, we can
6241 apply the distributive law to commute the multiply and addition
6242 if the multiplication of the constants doesn't overflow
6243 and overflow is defined. With undefined overflow
6244 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6250 op1);
6255 /* We have a special case here if we are doing something like
6256 (C * 8) % 4 since we know that's zero. */
6259 /* If the multiplication can overflow we cannot optimize this. */
6263 {
6266 }
6268 /* ... fall through ... */
6272 /* If we can extract our operation from the LHS, do so and return a
6273 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6274 do something only if the second operand is a constant. */
6288 /* If these are the same operation types, we can associate them
6289 assuming no overflow. */
6291 {
6306 }
6308 /* If these operations "cancel" each other, we have the main
6309 optimizations of this pass, which occur when either constant is a
6310 multiple of the other, in which case we replace this with either an
6311 operation or CODE or TCODE.
6313 If we have an unsigned type, we cannot do this since it will change
6314 the result if the original computation overflowed. */
6321 {
6323 {
6330 }
6332 {
6339 }
6340 }
6345 }
6348 }
6349 \f
6350 /* Return a node which has the indicated constant VALUE (either 0 or
6351 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6352 and is of the indicated TYPE. */
6354 tree
6356 {
6365 else
6367 }
6370 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6371 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6372 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6373 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6374 COND is the first argument to CODE; otherwise (as in the example
6375 given here), it is the second argument. TYPE is the type of the
6376 original expression. Return NULL_TREE if no simplification is
6377 possible. */
6379 static tree
6384 {
6394 {
6398 /* If this operand throws an expression, then it does not make
6399 sense to try to perform a logical or arithmetic operation
6400 involving it. */
6405 }
6408 {
6413 }
6414 else
6415 /* Detect the case of mixing vector and scalar types - bail out. */
6421 /* This transformation is only worthwhile if we don't have to wrap ARG
6422 in a SAVE_EXPR and the operation can be simplified without recursing
6423 on at least one of the branches once its pushed inside the COND_EXPR. */
6432 {
6436 else
6438 }
6440 {
6444 else
6446 }
6448 /* Check that we have simplified at least one of the branches. */
6453 }
6455 \f
6456 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6458 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6459 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6460 ADDEND is the same as X.
6462 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6463 and finite. The problematic cases are when X is zero, and its mode
6464 has signed zeros. In the case of rounding towards -infinity,
6465 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6466 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6468 bool
6470 {
6474 /* Don't allow the fold with -fsignaling-nans. */
6478 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6482 /* In a vector or complex, we would need to check the sign of all zeros. */
6486 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6490 /* The mode has signed zeros, and we have to honor their sign.
6491 In this situation, there is only one case we can return true for.
6492 X - 0 is the same as X unless rounding towards -infinity is
6493 supported. */
6495 }
6497 /* Subroutine of fold() that optimizes comparisons of a division by
6498 a nonzero integer constant against an integer constant, i.e.
6499 X/C1 op C2.
6501 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6502 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6503 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6505 The function returns the constant folded tree if a simplification
6506 can be made, and NULL_TREE otherwise. */
6508 static tree
6511 {
6519 /* We have to do this the hard way to detect unsigned overflow.
6520 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6526 {
6531 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6535 }
6537 {
6541 {
6560 }
6561 }
6562 else
6563 {
6564 /* A negative divisor reverses the relational operators. */
6570 {
6589 }
6590 }
6593 {
6614 {
6617 }
6622 {
6625 }
6630 {
6633 }
6638 {
6641 }
6646 }
6649 }
6652 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6653 equality/inequality test, then return a simplified form of the test
6654 using a sign testing. Otherwise return NULL. TYPE is the desired
6655 result type. */
6657 static tree
6660 tree result_type)
6661 {
6662 /* If this is testing a single bit, we can optimize the test. */
6666 {
6667 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6668 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6672 /* This is only a win if casting to a signed type is cheap,
6673 i.e. when arg00's type is not a partial mode. */
6676 {
6679 result_type,
6682 }
6683 }
6686 }
6688 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6689 equality/inequality test, then return a simplified form of
6690 the test using shifts and logical operations. Otherwise return
6691 NULL. TYPE is the desired result type. */
6693 tree
6696 {
6697 /* If this is testing a single bit, we can optimize the test. */
6701 {
6710 /* First, see if we can fold the single bit test into a sign-bit
6711 test. */
6713 result_type);
6717 /* Otherwise we have (A & C) != 0 where C is a single bit,
6718 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6719 Similarly for (A & C) == 0. */
6721 /* If INNER is a right shift of a constant and it plus BITNUM does
6722 not overflow, adjust BITNUM and INNER. */
6728 {
6731 }
6733 /* If we are going to be able to omit the AND below, we must do our
6734 operations as unsigned. If we must use the AND, we have a choice.
6735 Normally unsigned is faster, but for some machines signed is. */
6753 /* Put the AND last so it can combine with more things. */
6756 /* Make sure to return the proper type. */
6760 }
6762 }
6764 /* Check whether we are allowed to reorder operands arg0 and arg1,
6765 such that the evaluation of arg1 occurs before arg0. */
6767 static bool
6769 {
6776 }
6778 /* Test whether it is preferable two swap two operands, ARG0 and
6779 ARG1, for example because ARG0 is an integer constant and ARG1
6780 isn't. If REORDER is true, only recommend swapping if we can
6781 evaluate the operands in reverse order. */
6783 bool
6785 {
6803 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6804 for commutative and comparison operators. Ensuring a canonical
6805 form allows the optimizers to find additional redundancies without
6806 having to explicitly check for both orderings. */
6812 /* Put SSA_NAMEs last. */
6818 /* Put variables last. */
6825 }
6828 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6829 means A >= Y && A != MAX, but in this case we know that
6830 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6832 static tree
6834 {
6841 else
6850 {
6853 }
6855 {
6858 }
6859 else
6866 {
6867 /* Convert the pointer types into integer before taking the difference. */
6871 }
6872 else
6879 }
6881 /* Fold a sum or difference of at least one multiplication.
6882 Returns the folded tree or NULL if no simplification could be made. */
6884 static tree
6887 {
6891 /* (A * C) +- (B * C) -> (A+-B) * C.
6892 (A * C) +- A -> A * (C+-1).
6893 We are most concerned about the case where C is a constant,
6894 but other combinations show up during loop reduction. Since
6895 it is not difficult, try all four possibilities. */
6898 {
6901 }
6903 {
6906 }
6907 else
6908 {
6909 /* We cannot generate constant 1 for fract. */
6914 }
6916 {
6919 }
6921 {
6923 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6924 the purpose of this canonicalization. */
6928 {
6931 }
6932 else
6934 }
6935 else
6936 {
6937 /* We cannot generate constant 1 for fract. */
6942 }
6954 /* No identical multiplicands; see if we can find a common
6955 power-of-two factor in non-power-of-two multiplies. This
6956 can help in multi-dimensional array access. */
6959 {
6962 tree maybe_same;
6966 /* Move min of absolute values to int11. */
6968 {
6973 }
6974 else
6978 /* The remainder should not be a constant, otherwise we
6979 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6980 increased the number of multiplications necessary. */
6982 {
6990 }
6991 }
7001 }
7003 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7004 specified by EXPR into the buffer PTR of length LEN bytes.
7005 Return the number of bytes placed in the buffer, or zero
7006 upon failure. */
7008 static int
7010 {
7024 {
7026 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7027 number of bytes. */
7031 {
7038 else
7040 }
7041 else
7046 }
7048 }
7051 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7052 specified by EXPR into the buffer PTR of length LEN bytes.
7053 Return the number of bytes placed in the buffer, or zero
7054 upon failure. */
7056 static int
7058 {
7062 FIXED_VALUE_TYPE value;
7078 }
7081 /* Subroutine of native_encode_expr. Encode the REAL_CST
7082 specified by EXPR into the buffer PTR of length LEN bytes.
7083 Return the number of bytes placed in the buffer, or zero
7084 upon failure. */
7086 static int
7088 {
7094 /* There are always 32 bits in each long, no matter the size of
7095 the hosts long. We handle floating point representations with
7096 up to 192 bits. */
7110 {
7115 {
7122 else
7124 }
7125 else
7126 {
7129 {
7130 /* Reverse bytes within each long, or within the entire float
7131 if it's smaller than a long (for HFmode). */
7134 }
7135 }
7140 }
7142 }
7144 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7145 specified by EXPR into the buffer PTR of length LEN bytes.
7146 Return the number of bytes placed in the buffer, or zero
7147 upon failure. */
7149 static int
7151 {
7153 tree part;
7168 }
7171 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7172 specified by EXPR into the buffer PTR of length LEN bytes.
7173 Return the number of bytes placed in the buffer, or zero
7174 upon failure. */
7176 static int
7178 {
7188 {
7190 {
7193 }
7204 }
7206 }
7209 /* Subroutine of native_encode_expr. Encode the STRING_CST
7210 specified by EXPR into the buffer PTR of length LEN bytes.
7211 Return the number of bytes placed in the buffer, or zero
7212 upon failure. */
7214 static int
7216 {
7218 HOST_WIDE_INT total_bytes;
7232 {
7235 {
7238 }
7241 }
7242 else
7245 }
7248 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7249 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7250 buffer PTR of length LEN bytes. If OFF is not -1 then start
7251 the encoding at byte offset OFF and encode at most LEN bytes.
7252 Return the number of bytes placed in the buffer, or zero upon failure. */
7254 int
7256 {
7257 /* We don't support starting at negative offset and -1 is special. */
7262 {
7283 }
7284 }
7287 /* Subroutine of native_interpret_expr. Interpret the contents of
7288 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7289 If the buffer cannot be interpreted, return NULL_TREE. */
7291 static tree
7293 {
7303 }
7306 /* Subroutine of native_interpret_expr. Interpret the contents of
7307 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7308 If the buffer cannot be interpreted, return NULL_TREE. */
7310 static tree
7312 {
7314 double_int result;
7315 FIXED_VALUE_TYPE fixed_value;
7325 }
7328 /* Subroutine of native_interpret_expr. Interpret the contents of
7329 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7330 If the buffer cannot be interpreted, return NULL_TREE. */
7332 static tree
7334 {
7338 /* There are always 32 bits in each long, no matter the size of
7339 the hosts long. We handle floating point representations with
7340 up to 192 bits. */
7341 REAL_VALUE_TYPE r;
7352 {
7353 /* Both OFFSET and BYTE index within a long;
7354 bitpos indexes the whole float. */
7357 {
7364 else
7366 }
7367 else
7368 {
7371 {
7372 /* Reverse bytes within each long, or within the entire float
7373 if it's smaller than a long (for HFmode). */
7376 }
7377 }
7381 }
7385 }
7388 /* Subroutine of native_interpret_expr. Interpret the contents of
7389 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7390 If the buffer cannot be interpreted, return NULL_TREE. */
7392 static tree
7394 {
7409 }
7412 /* Subroutine of native_interpret_expr. Interpret the contents of
7413 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7414 If the buffer cannot be interpreted, return NULL_TREE. */
7416 static tree
7418 {
7431 {
7436 }
7438 }
7441 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7442 the buffer PTR of length LEN as a constant of type TYPE. For
7443 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7444 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7445 return NULL_TREE. */
7447 tree
7449 {
7451 {
7473 }
7474 }
7476 /* Returns true if we can interpret the contents of a native encoding
7477 as TYPE. */
7479 static bool
7481 {
7483 {
7496 }
7497 }
7499 /* Return true iff a constant of type TYPE is accepted by
7500 native_encode_expr. */
7502 bool
7504 {
7506 {
7516 }
7517 }
7519 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7520 TYPE at compile-time. If we're unable to perform the conversion
7521 return NULL_TREE. */
7523 static tree
7525 {
7526 /* We support up to 512-bit values (for V8DFmode). */
7530 /* Check that the host and target are sane. */
7539 }
7541 /* Build an expression for the address of T. Folds away INDIRECT_REF
7542 to avoid confusing the gimplify process. */
7544 tree
7546 {
7547 /* The size of the object is not relevant when talking about its address. */
7552 {
7557 }
7567 {
7572 }
7573 else
7577 }
7579 /* Build an expression for the address of T. */
7581 tree
7583 {
7587 }
7589 /* Fold a unary expression of code CODE and type TYPE with operand
7590 OP0. Return the folded expression if folding is successful.
7591 Otherwise, return NULL_TREE. */
7593 tree
7595 {
7596 tree tem;
7597 tree arg0;
7605 {
7608 {
7609 /* Don't use STRIP_NOPS, because signedness of argument type
7610 matters. */
7612 }
7613 else
7614 {
7615 /* Strip any conversions that don't change the mode. This
7616 is safe for every expression, except for a comparison
7617 expression because its signedness is derived from its
7618 operands.
7620 Note that this is done as an internal manipulation within
7621 the constant folder, in order to find the simplest
7622 representation of the arguments so that their form can be
7623 studied. In any cases, the appropriate type conversions
7624 should be put back in the tree that will get out of the
7625 constant folder. */
7627 }
7630 {
7633 {
7637 }
7638 }
7639 }
7646 {
7653 {
7667 /* If this was a conversion, and all we did was to move into
7668 inside the COND_EXPR, bring it back out. But leave it if
7669 it is a conversion from integer to integer and the
7670 result precision is no wider than a word since such a
7671 conversion is cheap and may be optimized away by combine,
7672 while it couldn't if it were outside the COND_EXPR. Then return
7673 so we don't get into an infinite recursion loop taking the
7674 conversion out and then back in. */
7686 && (INTEGRAL_TYPE_P
7699 }
7700 }
7703 {
7709 CASE_CONVERT:
7713 {
7714 /* If we have (type) (a CMP b) and type is an integral type, return
7715 new expression involving the new type. Canonicalize
7716 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7717 non-integral type.
7718 Do not fold the result as that would not simplify further, also
7719 folding again results in recursions. */
7729 }
7731 /* Handle (T *)&A.B.C for A being of type T and B and C
7732 living at offset zero. This occurs frequently in
7733 C++ upcasting and then accessing the base. */
7737 {
7739 tree offset;
7740 machine_mode mode;
7742 tree base
7746 /* If the reference was to a (constant) zero offset, we can use
7747 the address of the base if it has the same base type
7748 as the result type and the pointer type is unqualified. */
7755 }
7759 /* Detect assigning a bitfield. */
7761 && DECL_BIT_FIELD
7763 {
7764 /* Don't leave an assignment inside a conversion
7765 unless assigning a bitfield. */
7767 /* First do the assignment, then return converted constant. */
7772 }
7774 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7775 constants (if x has signed type, the sign bit cannot be set
7776 in c). This folds extension into the BIT_AND_EXPR.
7777 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7778 very likely don't have maximal range for their precision and this
7779 transformation effectively doesn't preserve non-maximal ranges. */
7783 {
7794 <= HOST_BITS_PER_WIDE_INT
7796 {
7800 cst &= HOST_WIDE_INT_M1U
7804 && !flag_syntax_only
7807 {
7811 }
7812 }
7814 {
7819 }
7820 }
7822 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7823 cast (T1)X will fold away. We assume that this happens when X itself
7824 is a cast. */
7828 {
7832 return fold_build_pointer_plus_loc
7834 }
7836 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7837 of the same precision, and X is an integer type not narrower than
7838 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7844 {
7850 }
7852 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7853 type of X and Y (integer types only). */
7858 {
7859 /* Be careful not to introduce new overflows. */
7860 tree mult_type;
7863 else
7867 {
7874 }
7875 }
7881 {
7888 }
7899 /* Convert fabs((double)float) into (double)fabsf(float). */
7902 {
7908 targ0));
7909 }
7913 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7932 /* Note that the operand of this must be an int
7933 and its values must be 0 or 1.
7934 ("true" is a fixed value perhaps depending on the language,
7935 but we don't handle values other than 1 correctly yet.) */
7942 /* Fold *&X to X if X is an lvalue. */
7944 {
7951 }
7957 }
7960 /* If the operation was a conversion do _not_ mark a resulting constant
7961 with TREE_OVERFLOW if the original constant was not. These conversions
7962 have implementation defined behavior and retaining the TREE_OVERFLOW
7963 flag here would confuse later passes such as VRP. */
7964 tree
7967 {
7976 }
7978 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7979 operands OP0 and OP1. LOC is the location of the resulting expression.
7980 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7981 Return the folded expression if folding is successful. Otherwise,
7982 return NULL_TREE. */
7983 static tree
7986 {
7987 tree tem;
7989 /* We only do these simplifications if we are optimizing. */
7993 /* Check for things like (A || B) && (A || C). We can convert this
7994 to A || (B && C). Note that either operator can be any of the four
7995 truth and/or operations and the transformation will still be
7996 valid. Also note that we only care about order for the
7997 ANDIF and ORIF operators. If B contains side effects, this
7998 might change the truth-value of A. */
8005 {
8025 /* This case if tricky because we must either have commutative
8026 operators or else A10 must not have side-effects. */
8032 a01);
8033 }
8035 /* See if we can build a range comparison. */
8041 {
8045 }
8049 {
8053 }
8055 /* Check for the possibility of merging component references. If our
8056 lhs is another similar operation, try to merge its rhs with our
8057 rhs. Then try to merge our lhs and rhs. */
8071 {
8078 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8079 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8080 We don't want to pack more than two leafs to a non-IF AND/OR
8081 expression.
8082 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8083 equal to IF-CODE, then we don't want to add right-hand operand.
8084 If the inner right-hand side of left-hand operand has
8085 side-effects, or isn't simple, then we can't add to it,
8086 as otherwise we might destroy if-sequence. */
8089 /* Needed for sequence points to handle trappings, and
8090 side-effects. */
8092 {
8094 arg1);
8096 tem);
8097 }
8098 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8099 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8102 /* Needed for sequence points to handle trappings, and
8103 side-effects. */
8105 {
8110 }
8111 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8112 into (A OR B).
8113 For sequence point consistancy, we need to check for trapping,
8114 and side-effects. */
8118 }
8121 }
8123 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8124 by changing CODE to reduce the magnitude of constants involved in
8125 ARG0 of the comparison.
8126 Returns a canonicalized comparison tree if a simplification was
8127 possible, otherwise returns NULL_TREE.
8128 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8129 valid if signed overflow is undefined. */
8131 static tree
8135 {
8140 /* Match A +- CST code arg1. We can change this only if overflow
8141 is undefined. */
8144 /* In principle pointers also have undefined overflow behavior,
8145 but that causes problems elsewhere. */
8152 /* Identify the constant in arg0 and its sign. */
8156 /* Overflowed constants and zero will cause problems. */
8161 /* See if we can reduce the magnitude of the constant in
8162 arg0 by changing the comparison code. */
8163 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8167 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8171 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8175 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8179 else
8183 /* Now build the constant reduced in magnitude. But not if that
8184 would produce one outside of its types range. */
8200 }
8202 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8203 overflow further. Try to decrease the magnitude of constants involved
8204 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8205 and put sole constants at the second argument position.
8206 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8208 static tree
8211 {
8212 tree t;
8217 /* Try canonicalization by simplifying arg0. */
8222 {
8226 }
8228 /* Try canonicalization by simplifying arg1 using the swapped
8229 comparison. */
8237 }
8239 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8240 space. This is used to avoid issuing overflow warnings for
8241 expressions like &p->x which can not wrap. */
8243 static bool
8245 {
8252 wide_int wi_offset;
8258 else
8274 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8275 array. */
8277 {
8278 HOST_WIDE_INT base_size;
8283 }
8286 }
8288 /* Return a positive integer when the symbol DECL is known to have
8289 a nonzero address, zero when it's known not to (e.g., it's a weak
8290 symbol), and a negative integer when the symbol is not yet in the
8291 symbol table and so whether or not its address is zero is unknown. */
8292 static int
8294 {
8300 }
8302 /* Subroutine of fold_binary. This routine performs all of the
8303 transformations that are common to the equality/inequality
8304 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8305 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8306 fold_binary should call fold_binary. Fold a comparison with
8307 tree code CODE and type TYPE with operands OP0 and OP1. Return
8308 the folded comparison or NULL_TREE. */
8310 static tree
8313 {
8323 /* For comparisons of pointers we can decompose it to a compile time
8324 comparison of the base objects and the offsets into the object.
8325 This requires at least one operand being an ADDR_EXPR or a
8326 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8332 {
8335 machine_mode mode;
8339 /* Get base and offset for the access. Strip ADDR_EXPR for
8340 get_inner_reference, but put it back by stripping INDIRECT_REF
8341 off the base object if possible. indirect_baseN will be true
8342 if baseN is not an address but refers to the object itself. */
8345 {
8346 base0
8352 else
8354 }
8356 {
8360 {
8361 base0
8367 else
8369 }
8372 else
8376 {
8382 {
8385 }
8386 }
8387 }
8391 {
8392 base1
8398 else
8400 }
8402 {
8406 {
8407 base1
8413 else
8415 }
8418 else
8422 {
8428 {
8431 }
8432 }
8433 }
8435 /* If we have equivalent bases we might be able to simplify. */
8439 {
8440 /* We can fold this expression to a constant if the non-constant
8441 offset parts are equal. */
8445 && (equality_code
8446 || (indirect_base0
8450 {
8456 "occur when comparing P +- C1 with "
8458 WARN_STRICT_OVERFLOW_CONDITIONAL);
8461 {
8475 }
8476 }
8477 /* We can simplify the comparison to a comparison of the variable
8478 offset parts if the constant offset parts are equal.
8479 Be careful to use signed sizetype here because otherwise we
8480 mess with array offsets in the wrong way. This is possible
8481 because pointer arithmetic is restricted to retain within an
8482 object and overflow on pointer differences is undefined as of
8483 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8485 && (equality_code
8486 || (indirect_base0
8489 {
8490 /* By converting to signed sizetype we cover middle-end pointer
8491 arithmetic which operates on unsigned pointer types of size
8492 type size and ARRAY_REF offsets which are properly sign or
8493 zero extended from their type in case it is narrower than
8494 sizetype. */
8497 else
8501 else
8508 "occur when comparing P +- C1 with "
8510 WARN_STRICT_OVERFLOW_COMPARISON);
8513 }
8514 }
8515 /* For equal offsets we can simplify to a comparison of the
8516 base addresses. */
8518 && (indirect_base0
8520 && (indirect_base1
8525 {
8531 }
8532 /* Comparison between an ordinary (non-weak) symbol and a null
8533 pointer can be eliminated since such symbols must have a non
8534 null address. In C, relational expressions between pointers
8535 to objects and null pointers are undefined. The results
8536 below follow the C++ rules with the additional property that
8537 every object pointer compares greater than a null pointer.
8538 */
8541 /* Avoid folding references to struct members at offset 0 to
8542 prevent tests like '&ptr->firstmember == 0' from getting
8543 eliminated. When ptr is null, although the -> expression
8544 is strictly speaking invalid, GCC retains it as a matter
8545 of QoI. See PR c/44555. */
8547 /* The caller guarantees that when one of the arguments is
8548 constant (i.e., null in this case) it is second. */
8550 {
8552 {
8563 }
8564 }
8565 }
8567 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8568 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8569 the resulting offset is smaller in absolute value than the
8570 original one and has the same sign. */
8579 {
8584 tree cst;
8586 "occur when combining constants around "
8589 /* Put the constant on the side where it doesn't overflow and is
8590 of lower absolute value and of same sign than before. */
8597 {
8600 variable1,
8604 }
8612 {
8618 variable2);
8619 }
8620 }
8626 /* If we are comparing an expression that just has comparisons
8627 of two integer values, arithmetic expressions of those comparisons,
8628 and constants, we can simplify it. There are only three cases
8629 to check: the two values can either be equal, the first can be
8630 greater, or the second can be greater. Fold the expression for
8631 those three values. Since each value must be 0 or 1, we have
8632 eight possibilities, each of which corresponds to the constant 0
8633 or 1 or one of the six possible comparisons.
8635 This handles common cases like (a > b) == 0 but also handles
8636 expressions like ((x > y) - (y > x)) > 0, which supposedly
8637 occur in macroized code. */
8640 {
8645 /* Don't handle degenerate cases here; they should already
8646 have been handled anyway. */
8655 {
8659 /* We can't just pass T to eval_subst in case cval1 or cval2
8660 was the same as ARG1. */
8662 tree high_result
8666 arg1);
8667 tree equal_result
8671 arg1);
8672 tree low_result
8676 arg1);
8678 /* All three of these results should be 0 or 1. Confirm they are.
8679 Then use those values to select the proper code to use. */
8684 {
8685 /* Make a 3-bit mask with the high-order bit being the
8686 value for `>', the next for '=', and the low for '<'. */
8690 {
8692 /* Always false. */
8713 /* Always true. */
8715 }
8718 {
8722 }
8724 }
8725 }
8726 }
8728 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8729 into a single range test. */
8737 {
8741 }
8744 }
8747 /* Subroutine of fold_binary. Optimize complex multiplications of the
8748 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8749 argument EXPR represents the expression "z" of type TYPE. */
8751 static tree
8753 {
8758 {
8761 }
8763 {
8766 }
8767 else
8768 {
8772 }
8781 }
8784 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8785 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8787 static bool
8789 {
8793 {
8796 }
8798 {
8804 else
8806 }
8807 else
8813 }
8815 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8816 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8817 NULL_TREE otherwise. */
8819 static tree
8821 {
8838 {
8842 }
8845 {
8851 }
8852 else
8854 }
8856 /* Try to fold a pointer difference of type TYPE two address expressions of
8857 array references AREF0 and AREF1 using location LOC. Return a
8858 simplified expression for the difference or NULL_TREE. */
8860 static tree
8863 {
8868 /* If the bases are array references as well, recurse. If the bases
8869 are pointer indirections compute the difference of the pointers.
8870 If the bases are equal, we are set. */
8873 && (base_offset
8877 && (base_offset
8883 {
8889 base_offset,
8892 }
8894 }
8896 /* If the real or vector real constant CST of type TYPE has an exact
8897 inverse, return it, else return NULL. */
8899 tree
8901 {
8902 REAL_VALUE_TYPE r;
8904 machine_mode mode;
8908 {
8924 {
8929 }
8935 }
8936 }
8938 /* Mask out the tz least significant bits of X of type TYPE where
8939 tz is the number of trailing zeroes in Y. */
8940 static wide_int
8942 {
8947 }
8949 /* Return true when T is an address and is known to be nonzero.
8950 For floating point we further ensure that T is not denormal.
8951 Similar logic is present in nonzero_address in rtlanal.h.
8953 If the return value is based on the assumption that signed overflow
8954 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8955 change *STRICT_OVERFLOW_P. */
8957 static bool
8959 {
8963 /* Doing something useful for floating point would need more work. */
8969 {
8972 strict_overflow_p);
8978 strict_overflow_p);
8986 }
8989 {
8992 strict_overflow_p);
9000 strict_overflow_p);
9015 strict_overflow_p);
9019 strict_overflow_p);
9022 {
9034 }
9038 }
9040 }
9042 /* Return true when T is an address and is known to be nonzero.
9043 Handle warnings about undefined signed overflow. */
9045 static bool
9047 {
9054 "determining that expression is always "
9056 WARN_STRICT_OVERFLOW_MISC);
9058 }
9060 /* Return true if T is known not to be equal to an integer W. */
9062 bool
9064 {
9066 value_range_type rtype;
9068 {
9077 {
9082 }
9087 /* If T has some known zero bits and W has any of those bits set,
9088 then T is known not to be equal to W. */
9096 }
9097 }
9099 /* Fold a binary expression of code CODE and type TYPE with operands
9100 OP0 and OP1. LOC is the location of the resulting expression.
9101 Return the folded expression if folding is successful. Otherwise,
9102 return NULL_TREE. */
9104 tree
9107 {
9122 /* Strip any conversions that don't change the mode. This is
9123 safe for every expression, except for a comparison expression
9124 because its signedness is derived from its operands. So, in
9125 the latter case, only strip conversions that don't change the
9126 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9127 preserved.
9129 Note that this is done as an internal manipulation within the
9130 constant folder, in order to find the simplest representation
9131 of the arguments so that their form can be studied. In any
9132 cases, the appropriate type conversions should be put back in
9133 the tree that will get out of the constant folder. */
9136 {
9139 }
9140 else
9141 {
9144 }
9146 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9147 constant but we can't do arithmetic on them. */
9149 {
9152 {
9156 }
9157 }
9159 /* If this is a commutative operation, and ARG0 is a constant, move it
9160 to ARG1 to reduce the number of tests below. */
9165 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9166 to ARG1 to reduce the number of tests below. */
9175 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9177 First check for cases where an arithmetic operation is applied to a
9178 compound, conditional, or comparison operation. Push the arithmetic
9179 operation inside the compound or conditional to see if any folding
9180 can then be done. Convert comparison to conditional for this purpose.
9181 The also optimizes non-constant cases that used to be done in
9182 expand_expr.
9184 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9185 one of the operands is a comparison and the other is a comparison, a
9186 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9187 code below would make the expression more complex. Change it to a
9188 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9189 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9202 {
9206 boolean_type_node,
9214 }
9218 {
9220 {
9225 tem);
9226 }
9229 {
9234 tem);
9235 }
9240 {
9246 }
9251 {
9257 }
9258 }
9261 {
9263 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9266 {
9272 }
9274 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9277 {
9278 tree base;
9279 HOST_WIDE_INT coffset;
9288 }
9293 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9299 arg1),
9301 arg0)));
9307 {
9308 /* X + (X / CST) * -CST is X % CST. */
9313 {
9322 cst0));
9323 }
9324 }
9326 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9327 one. Make sure the type is not saturating and has the signedness of
9328 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9329 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9336 {
9340 }
9343 {
9344 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9345 (plus (plus (mult) (mult)) (foo)) so that we can
9346 take advantage of the factoring cases below. */
9355 {
9361 else
9374 parg0),
9376 marg)),
9380 return
9386 parg1)));
9387 }
9388 }
9389 else
9390 {
9391 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9392 to __complex__ ( x, y ). This is not the same for SNaNs or
9393 if signed zeros are involved. */
9397 {
9404 {
9408 {
9414 }
9416 {
9422 }
9423 }
9424 }
9432 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9433 We associate floats only if the user has specified
9434 -fassociative-math. */
9438 {
9443 {
9444 tree tree0;
9447 }
9448 }
9449 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9450 We associate floats only if the user has specified
9451 -fassociative-math. */
9455 {
9460 {
9461 tree tree0;
9464 }
9465 }
9466 }
9468 bit_rotate:
9469 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9470 is a rotate of A by C1 bits. */
9471 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9472 is a rotate of A by B bits. */
9473 {
9475 tree rtype;
9484 /* Only create rotates in complete modes. Other cases are not
9485 expanded properly. */
9488 {
9502 {
9506 code0 == LSHIFT_EXPR
9510 }
9512 {
9520 element_precision
9524 return
9527 ? LROTATE_EXPR
9532 }
9534 {
9542 element_precision
9546 return fold_convert_loc
9549 ? LROTATE_EXPR
9553 }
9554 }
9555 }
9557 associate:
9558 /* In most languages, can't associate operations on floats through
9559 parentheses. Rather than remember where the parentheses were, we
9560 don't associate floats at all, unless the user has specified
9561 -fassociative-math.
9562 And, we need to make sure type is not saturating. */
9566 {
9572 /* Split both trees into variables, constants, and literals. Then
9573 associate each group together, the constants with literals,
9574 then the result with variables. This increases the chances of
9575 literals being recombined later and of generating relocatable
9576 expressions for the sum of a constant and literal. */
9582 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9586 /* With undefined overflow prefer doing association in a type
9587 which wraps on overflow, if that is one of the operand types. */
9590 {
9598 }
9600 /* With undefined overflow we can only associate constants with one
9601 variable, and constants whose association doesn't overflow. */
9604 {
9606 {
9612 {
9615 }
9622 {
9625 }
9631 /* The only case we can still associate with two variables
9632 is if they cancel out. */
9636 }
9637 }
9639 /* Only do something if we found more than two objects. Otherwise,
9640 nothing has changed and we risk infinite recursion. */
9646 {
9658 /* Preserve the MINUS_EXPR if the negative part of the literal is
9659 greater than the positive part. Otherwise, the multiplicative
9660 folding code (i.e extract_muldiv) may be fooled in case
9661 unsigned constants are subtracted, like in the following
9662 example: ((X*2 + 4) - 8U)/2. */
9664 {
9668 {
9672 }
9673 else
9674 {
9678 }
9679 }
9681 /* Don't introduce overflows through reassociation. */
9688 {
9690 return
9694 else
9695 {
9698 return
9702 }
9703 }
9706 return
9709 }
9710 }
9715 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9724 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9725 __complex__ ( x, -y ). This is not the same for SNaNs or if
9726 signed zeros are involved. */
9730 {
9737 {
9741 {
9743 arg1r ? arg1r
9748 }
9750 {
9754 arg1i ? arg1i
9757 }
9758 }
9759 }
9761 /* A - B -> A + (-B) if B is easily negatable. */
9765 /* Avoid this transformation if B is a positive REAL_CST. */
9773 /* Fold &a[i] - &a[j] to i-j. */
9778 {
9784 }
9787 && flag_unsafe_math_optimizations
9793 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9794 one. Make sure the type is not saturating and has the signedness of
9795 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9796 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9803 {
9807 }
9813 {
9814 /* Transform x * -C into -x * C if x is easily negatable. */
9828 {
9831 "occur when simplifying "
9833 WARN_STRICT_OVERFLOW_MISC);
9835 }
9837 /* Optimize z * conj(z) for integer complex numbers. */
9844 }
9845 else
9846 {
9847 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9848 This is not the same for NaNs or if signed zeros are
9849 involved. */
9855 {
9858 return
9864 return
9869 }
9871 /* Optimize z * conj(z) for floating point complex numbers.
9872 Guarded by flag_unsafe_math_optimizations as non-finite
9873 imaginary components don't produce scalar results. */
9882 }
9886 /* Canonicalize (X & C1) | C2. */
9890 {
9895 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9903 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9908 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9909 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9910 mode which allows further optimizations. */
9915 {
9919 {
9922 }
9923 }
9930 c3)),
9931 arg1);
9932 }
9934 /* See if this can be simplified into a rotate first. If that
9935 is unsuccessful continue in the association code. */
9939 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9947 /* See if this can be simplified into a rotate first. If that
9948 is unsuccessful continue in the association code. */
9952 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9957 {
9958 tree tem2;
9965 }
9966 /* Fold ~X & 1 as (X & 1) == 0. */
9970 {
9971 tree tem2;
9978 }
9979 /* Fold !X & 1 as X == 0. */
9982 {
9986 }
9988 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9989 multiple of 1 << CST. */
9991 {
9998 }
10000 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10001 bits from CST2. */
10005 {
10013 {
10014 /* Avoid the transform if arg1 is a mask of some
10015 mode which allows further optimizations. */
10022 }
10023 }
10025 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10026 ((A & N) + B) & M -> (A + B) & M
10027 Similarly if (N & M) == 0,
10028 ((A | N) + B) & M -> (A + B) & M
10029 and for - instead of + (or unary - instead of +)
10030 and/or ^ instead of |.
10031 If B is constant and (B & M) == 0, fold into A & M. */
10033 {
10042 {
10045 wide_int cst0;
10047 /* Now we know that arg0 is (C + D) or (C - D) or
10048 -C and arg1 (M) is == (1LL << cst) - 1.
10049 Store C into PMOP[0] and D into PMOP[1]. */
10053 {
10056 }
10063 {
10073 {
10076 }
10079 /* If C or D is of the form (A & N) where
10080 (N & M) == M, or of the form (A | N) or
10081 (A ^ N) where (N & M) == 0, replace it with A. */
10085 /* If C or D is a N where (N & M) == 0, it can be
10086 omitted (assumed 0). */
10094 }
10096 /* Only build anything new if we optimized one or both arguments
10097 above. */
10101 {
10104 {
10105 /* Perform the operations in a type that has defined
10106 overflow behavior. */
10112 }
10117 {
10125 else
10127 }
10130 else
10133 /* TEM is now the new binary +, - or unary - replacement. */
10137 }
10138 }
10139 }
10141 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10144 {
10149 return
10151 }
10156 /* Don't touch a floating-point divide by zero unless the mode
10157 of the constant can represent infinity. */
10163 /* (-A) / (-B) -> A / B */
10175 /* Fall through */
10178 /* Simplify A / (B << N) where A and B are positive and B is
10179 a power of 2, to A >> (N + log2(B)). */
10184 {
10187 {
10195 WARN_STRICT_OVERFLOW_MISC);
10201 }
10202 }
10204 /* Fall through */
10212 /* Convert -A / -B to A / B when the type is signed and overflow is
10213 undefined. */
10217 {
10220 "when distributing negation across "
10222 WARN_STRICT_OVERFLOW_MISC);
10227 }
10231 {
10234 "when distributing negation across "
10236 WARN_STRICT_OVERFLOW_MISC);
10241 }
10243 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10244 operation, EXACT_DIV_EXPR.
10246 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10247 At one time others generated faster code, it's not clear if they do
10248 after the last round to changes to the DIV code in expmed.c. */
10259 {
10263 WARN_STRICT_OVERFLOW_MISC);
10265 }
10277 {
10281 WARN_STRICT_OVERFLOW_MISC);
10283 }
10291 /* Since negative shift count is not well-defined,
10292 don't try to compute it in the compiler. */
10298 /* If we have a rotate of a bit operation with the rotate count and
10299 the second operand of the bit operation both constant,
10300 permute the two operations. */
10306 {
10314 }
10316 /* Two consecutive rotates adding up to the some integer
10317 multiple of the precision of the type can be ignored. */
10332 /* Note that the operands of this must be ints
10333 and their values must be 0 or 1.
10334 ("true" is a fixed value perhaps depending on the language.) */
10335 /* If first arg is constant zero, return it. */
10338 /* FALLTHRU */
10340 /* If either arg is constant true, drop it. */
10344 /* Preserve sequence points. */
10347 /* If second arg is constant zero, result is zero, but first arg
10348 must be evaluated. */
10351 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10352 case will be handled here. */
10356 /* !X && X is always false. */
10360 /* X && !X is always false. */
10365 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10366 means A >= Y && A != MAX, but in this case we know that
10367 A < X <= MAX. */
10371 {
10379 }
10388 /* Note that the operands of this must be ints
10389 and their values must be 0 or true.
10390 ("true" is a fixed value perhaps depending on the language.) */
10391 /* If first arg is constant true, return it. */
10394 /* FALLTHRU */
10396 /* If either arg is constant zero, drop it. */
10400 /* Preserve sequence points. */
10403 /* If second arg is constant true, result is true, but we must
10404 evaluate first arg. */
10407 /* Likewise for first arg, but note this only occurs here for
10408 TRUTH_OR_EXPR. */
10412 /* !X || X is always true. */
10416 /* X || !X is always true. */
10421 /* (X && !Y) || (!X && Y) is X ^ Y */
10424 {
10441 }
10450 /* If the second arg is constant zero, drop it. */
10453 /* If the second arg is constant true, this is a logical inversion. */
10455 {
10458 }
10459 /* Identical arguments cancel to zero. */
10463 /* !X ^ X is always true. */
10468 /* X ^ !X is always true. */
10484 /* bool_var != 1 becomes !bool_var. */
10491 /* bool_var == 0 becomes !bool_var. */
10498 /* !exp != 0 becomes !exp */
10503 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10512 {
10518 }
10520 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10529 {
10535 }
10537 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10545 code == NE_EXPR
10549 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10557 code == NE_EXPR
10561 /* If this is an EQ or NE comparison with zero and ARG0 is
10562 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10563 two operations, but the latter can be done in one less insn
10564 on machines that have only two-operand insns or on which a
10565 constant cannot be the first operand. */
10568 {
10573 {
10580 arg1);
10581 }
10584 {
10591 arg1);
10592 }
10593 }
10595 /* If this is an NE or EQ comparison of zero against the result of a
10596 signed MOD operation whose second operand is a power of 2, make
10597 the MOD operation unsigned since it is simpler and equivalent. */
10605 {
10615 }
10617 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10618 C1 is a valid shift constant, and C2 is a power of two, i.e.
10619 a single bit. */
10623 == INTEGER_CST
10626 {
10631 /* Check for a valid shift count. */
10633 {
10637 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10638 can be rewritten as (X & (C2 << C1)) != 0. */
10640 {
10645 }
10646 /* Otherwise, for signed (arithmetic) shifts,
10647 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10648 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10652 /* Otherwise, of unsigned (logical) shifts,
10653 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10654 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10655 else
10659 arg000);
10660 }
10661 }
10663 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10664 Similarly for NE_EXPR. */
10668 {
10672 tree dandnotc
10675 notc);
10679 }
10681 /* If this is a comparison of a field, we may be able to simplify it. */
10684 /* Handle the constant case even without -O
10685 to make sure the warnings are given. */
10687 {
10691 }
10693 /* Optimize comparisons of strlen vs zero to a compare of the
10694 first character of the string vs zero. To wit,
10695 strlen(ptr) == 0 => *ptr == 0
10696 strlen(ptr) != 0 => *ptr != 0
10697 Other cases should reduce to one of these two (or a constant)
10698 due to the return value of strlen being unsigned. */
10701 {
10709 {
10714 }
10715 }
10717 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10718 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10722 {
10727 {
10729 {
10732 }
10735 }
10736 }
10738 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10739 (X & C) == 0 when C is a single bit. */
10744 {
10751 arg1));
10752 }
10754 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10755 constant C is a power of two, i.e. a single bit. */
10762 {
10766 }
10768 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10769 when is C is a power of two, i.e. a single bit. */
10776 {
10782 }
10786 {
10789 }
10791 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10794 {
10807 arg01),
10816 arg01),
10825 arg00),
10834 arg00),
10836 }
10840 {
10847 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10848 operand_equal_p guarantees no side-effects so we don't need
10849 to use omit_one_operand on Z. */
10853 arg10));
10857 arg11));
10861 arg10));
10865 arg11));
10867 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10870 {
10876 }
10877 }
10879 /* Attempt to simplify equality/inequality comparisons of complex
10880 values. Only lower the comparison if the result is known or
10881 can be simplified to a single scalar comparison. */
10886 {
10891 {
10894 }
10895 else
10896 {
10899 }
10902 {
10905 }
10906 else
10907 {
10910 }
10914 {
10916 {
10921 }
10922 else
10923 {
10928 }
10929 }
10933 {
10935 {
10940 }
10941 else
10942 {
10947 }
10948 }
10949 }
10961 /* Transform comparisons of the form X +- C CMP X. */
10968 {
10975 else
10978 /* (X - c) > X becomes false. */
10982 {
10986 "occur when assuming that (X - c) > X "
10988 WARN_STRICT_OVERFLOW_ALL);
10990 }
10992 /* Likewise (X + c) < X becomes false. */
10996 {
11000 "occur when assuming that "
11002 WARN_STRICT_OVERFLOW_ALL);
11004 }
11006 /* Convert (X - c) <= X to true. */
11011 {
11015 "occur when assuming that "
11017 WARN_STRICT_OVERFLOW_ALL);
11019 }
11021 /* Convert (X + c) >= X to true. */
11026 {
11030 "occur when assuming that "
11032 WARN_STRICT_OVERFLOW_ALL);
11034 }
11037 {
11038 /* Convert X + c > X and X - c < X to true for integers. */
11042 {
11045 "not occur when assuming that "
11047 WARN_STRICT_OVERFLOW_ALL);
11049 }
11054 {
11057 "not occur when assuming that "
11059 WARN_STRICT_OVERFLOW_ALL);
11061 }
11063 /* Convert X + c <= X and X - c >= X to false for integers. */
11067 {
11070 "not occur when assuming that "
11072 WARN_STRICT_OVERFLOW_ALL);
11074 }
11079 {
11082 "not occur when assuming that "
11084 WARN_STRICT_OVERFLOW_ALL);
11086 }
11087 }
11088 }
11090 /* If we are comparing an ABS_EXPR with a constant, we can
11091 convert all the cases into explicit comparisons, but they may
11092 well not be faster than doing the ABS and one comparison.
11093 But ABS (X) <= C is a range comparison, which becomes a subtraction
11094 and a comparison, and is probably faster. */
11108 /* Convert ABS_EXPR<x> >= 0 to true. */
11115 {
11118 "when simplifying comparison of "
11120 WARN_STRICT_OVERFLOW_CONDITIONAL);
11123 arg0);
11124 }
11126 /* Convert ABS_EXPR<x> < 0 to false. */
11131 {
11134 "when simplifying comparison of "
11136 WARN_STRICT_OVERFLOW_CONDITIONAL);
11139 arg0);
11140 }
11142 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11143 and similarly for >= into !=. */
11153 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11154 otherwise Y might be >= # of bits in X's type and thus e.g.
11155 (unsigned char) (1 << Y) for Y 15 might be 0.
11156 If the cast is widening, then 1 << Y should have unsigned type,
11157 otherwise if Y is number of bits in the signed shift type minus 1,
11158 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11159 31 might be 0xffffffff80000000. */
11170 {
11176 }
11188 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11189 {
11201 }
11206 /* When pedantic, a compound expression can be neither an lvalue
11207 nor an integer constant expression. */
11210 /* Don't let (0, 0) be null pointer constant. */
11216 /* An ASSERT_EXPR should never be passed to fold_binary. */
11222 }
11224 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11225 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11226 of GOTO_EXPR. */
11228 static tree
11230 {
11232 {
11239 /* fall through */
11243 }
11244 }
11246 /* Return whether the sub-tree ST contains a label which is accessible from
11247 outside the sub-tree. */
11249 static bool
11251 {
11252 return
11254 }
11256 /* Fold a ternary expression of code CODE and type TYPE with operands
11257 OP0, OP1, and OP2. Return the folded expression if folding is
11258 successful. Otherwise, return NULL_TREE. */
11260 tree
11263 {
11264 tree tem;
11271 /* If this is a commutative operation, and OP0 is a constant, move it
11272 to OP1 to reduce the number of tests below. */
11281 /* Strip any conversions that don't change the mode. This is safe
11282 for every expression, except for a comparison expression because
11283 its signedness is derived from its operands. So, in the latter
11284 case, only strip conversions that don't change the signedness.
11286 Note that this is done as an internal manipulation within the
11287 constant folder, in order to find the simplest representation of
11288 the arguments so that their form can be studied. In any cases,
11289 the appropriate type conversions should be put back in the tree
11290 that will get out of the constant folder. */
11292 {
11295 }
11298 {
11301 }
11304 {
11307 }
11310 {
11314 {
11320 }
11325 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11326 so all simple results must be passed through pedantic_non_lvalue. */
11328 {
11331 /* Only optimize constant conditions when the selected branch
11332 has the same type as the COND_EXPR. This avoids optimizing
11333 away "c ? x : throw", where the throw has a void type.
11334 Avoid throwing away that operand which contains label. */
11341 }
11343 {
11348 {
11353 {
11361 }
11365 }
11366 }
11368 /* If we have A op B ? A : C, we may be able to convert this to a
11369 simpler expression, depending on the operation and the values
11370 of B and C. Signed zeros prevent all of these transformations,
11371 for reasons given above each one.
11373 Also try swapping the arguments and inverting the conditional. */
11378 {
11382 }
11386 op2,
11389 {
11393 {
11397 }
11398 }
11400 /* If the second operand is simpler than the third, swap them
11401 since that produces better jump optimization results. */
11404 {
11406 /* See if this can be inverted. If it can't, possibly because
11407 it was a floating-point inequality comparison, don't do
11408 anything. */
11412 }
11414 /* Convert A ? 1 : 0 to simply A. */
11419 /* If we try to convert OP0 to our type, the
11420 call to fold will try to move the conversion inside
11421 a COND, which will recurse. In that case, the COND_EXPR
11422 is probably the best choice, so leave it alone. */
11426 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11427 over COND_EXPR in cases such as floating point comparisons. */
11436 arg0)));
11438 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11443 {
11444 /* sign_bit_p looks through both zero and sign extensions,
11445 but for this optimization only sign extensions are
11446 usable. */
11449 {
11452 {
11455 }
11457 }
11458 /* sign_bit_p only checks ARG1 bits within A's precision.
11459 If <sign bit of A> has wider type than A, bits outside
11460 of A's precision in <sign bit of A> need to be checked.
11461 If they are all 0, this optimization needs to be done
11462 in unsigned A's type, if they are all 1 in signed A's type,
11463 otherwise this can't be done. */
11469 {
11471 tree tem_type;
11484 {
11487 }
11489 {
11492 }
11493 else
11495 }
11498 return
11504 arg1)));
11505 }
11507 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11508 already handled above. */
11513 {
11522 }
11524 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11525 is probably obsolete because the first operand should be a
11526 truth value (that's why we have the two cases above), but let's
11527 leave it in until we can confirm this for all front-ends. */
11539 /* Disable the transformations below for vectors, since
11540 fold_binary_op_with_conditional_arg may undo them immediately,
11541 yielding an infinite loop. */
11545 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11554 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11559 {
11561 /* Only perform transformation if ARG0 is easily inverted. */
11565 ? BIT_IOR_EXPR
11568 arg1);
11569 }
11571 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11576 {
11578 /* Only perform transformation if ARG0 is easily inverted. */
11584 op2);
11585 }
11587 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11599 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11600 of fold_ternary on them. */
11608 {
11618 {
11623 {
11631 }
11632 }
11633 }
11635 /* On constants we can use native encode/interpret to constant
11636 fold (nearly) all BIT_FIELD_REFs. */
11640 {
11643 /* Limit us to a reasonable amount of work. To relax the
11644 other limitations we need bit-shifting of the buffer
11645 and rounding up the size. */
11649 {
11651 unsigned HOST_WIDE_INT len
11656 {
11661 }
11662 }
11663 }
11668 /* For integers we can decompose the FMA if possible. */
11680 {
11696 {
11701 /* Make sure that the perm value is in an acceptable
11702 range. */
11711 else
11716 }
11719 {
11724 }
11729 {
11734 }
11740 {
11744 }
11749 /* Some targets are deficient and fail to expand a single
11750 argument permutation while still allowing an equivalent
11751 2-argument version. */
11755 {
11758 }
11761 {
11768 }
11772 }
11776 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11779 {
11785 wide_int tem2
11789 }
11794 {
11796 unsigned HOST_WIDE_INT elsize
11799 {
11803 else
11804 {
11810 }
11811 }
11812 }
11818 }
11820 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11821 of an array (or vector). */
11823 tree
11825 {
11830 {
11833 {
11834 /* Static constructors for variably sized objects makes no sense. */
11838 }
11839 }
11850 offset_int max_index;
11855 {
11856 /* Array constructor might explicitly set index, or specify a range,
11857 or leave index NULL meaning that it is next index after previous
11858 one. */
11860 {
11863 else
11864 {
11868 }
11869 }
11870 else
11871 {
11877 }
11879 /* Do we have match? */
11883 }
11885 }
11887 /* Perform constant folding and related simplification of EXPR.
11888 The related simplifications include x*1 => x, x*0 => 0, etc.,
11889 and application of the associative law.
11890 NOP_EXPR conversions may be removed freely (as long as we
11891 are careful not to change the type of the overall expression).
11892 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11893 but we can constant-fold them if they have constant operands. */
11895 #ifdef ENABLE_FOLD_CHECKING
11896 # define fold(x) fold_1 (x)
11898 static
11899 #endif
11900 tree
11902 {
11906 tree tem;
11909 /* Return right away if a constant. */
11913 /* CALL_EXPR-like objects with variable numbers of operands are
11914 treated specially. */
11916 {
11918 {
11921 }
11923 }
11926 {
11931 {
11949 }
11950 }
11953 {
11955 {
11962 {
11967 }
11970 }
11972 /* Return a VECTOR_CST if possible. */
11974 {
11980 tree val;
11986 }
11994 }
11996 #ifdef ENABLE_FOLD_CHECKING
11997 #undef fold
12004 /* When --enable-checking=fold, compute a digest of expr before
12005 and after actual fold call to see if fold did not accidentally
12006 change original expr. */
12008 tree
12010 {
12011 tree ret;
12031 }
12033 void
12035 {
12046 }
12048 static void
12050 {
12052 }
12054 static void
12057 {
12063 recursive_label:
12073 {
12074 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12079 }
12087 {
12088 /* Allow these fields to be modified. */
12089 tree tmp;
12098 {
12101 }
12102 }
12113 {
12116 {
12131 }
12135 {
12148 }
12165 {
12171 }
12174 {
12176 {
12179 }
12181 }
12192 {
12195 }
12205 }
12206 }
12208 /* Helper function for outputting the checksum of a tree T. When
12209 debugging with gdb, you can "define mynext" to be "next" followed
12210 by "call debug_fold_checksum (op0)", then just trace down till the
12211 outputs differ. */
12213 DEBUG_FUNCTION void
12215 {
12230 }
12232 #endif
12234 /* Fold a unary tree expression with code CODE of type TYPE with an
12235 operand OP0. LOC is the location of the resulting expression.
12236 Return a folded expression if successful. Otherwise, return a tree
12237 expression with code CODE of type TYPE with an operand OP0. */
12239 tree
12242 {
12243 tree tem;
12244 #ifdef ENABLE_FOLD_CHECKING
12253 #endif
12259 #ifdef ENABLE_FOLD_CHECKING
12266 #endif
12268 }
12270 /* Fold a binary tree expression with code CODE of type TYPE with
12271 operands OP0 and OP1. LOC is the location of the resulting
12272 expression. Return a folded expression if successful. Otherwise,
12273 return a tree expression with code CODE of type TYPE with operands
12274 OP0 and OP1. */
12276 tree
12279 MEM_STAT_DECL)
12280 {
12281 tree tem;
12282 #ifdef ENABLE_FOLD_CHECKING
12299 #endif
12305 #ifdef ENABLE_FOLD_CHECKING
12320 #endif
12322 }
12324 /* Fold a ternary tree expression with code CODE of type TYPE with
12325 operands OP0, OP1, and OP2. Return a folded expression if
12326 successful. Otherwise, return a tree expression with code CODE of
12327 type TYPE with operands OP0, OP1, and OP2. */
12329 tree
12332 {
12333 tree tem;
12334 #ifdef ENABLE_FOLD_CHECKING
12358 #endif
12365 #ifdef ENABLE_FOLD_CHECKING
12388 #endif
12390 }
12392 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12393 arguments in ARGARRAY, and a null static chain.
12394 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12395 of type TYPE from the given operands as constructed by build_call_array. */
12397 tree
12400 {
12401 tree tem;
12402 #ifdef ENABLE_FOLD_CHECKING
12421 #endif
12427 #ifdef ENABLE_FOLD_CHECKING
12443 #endif
12445 }
12447 /* Perform constant folding and related simplification of initializer
12448 expression EXPR. These behave identically to "fold_buildN" but ignore
12449 potential run-time traps and exceptions that fold must preserve. */
12451 #define START_FOLD_INIT \
12452 int saved_signaling_nans = flag_signaling_nans;\
12453 int saved_trapping_math = flag_trapping_math;\
12454 int saved_rounding_math = flag_rounding_math;\
12455 int saved_trapv = flag_trapv;\
12456 int saved_folding_initializer = folding_initializer;\
12457 flag_signaling_nans = 0;\
12458 flag_trapping_math = 0;\
12459 flag_rounding_math = 0;\
12460 flag_trapv = 0;\
12461 folding_initializer = 1;
12463 #define END_FOLD_INIT \
12464 flag_signaling_nans = saved_signaling_nans;\
12465 flag_trapping_math = saved_trapping_math;\
12466 flag_rounding_math = saved_rounding_math;\
12467 flag_trapv = saved_trapv;\
12468 folding_initializer = saved_folding_initializer;
12470 tree
12473 {
12474 tree result;
12475 START_FOLD_INIT;
12479 END_FOLD_INIT;
12481 }
12483 tree
12486 {
12487 tree result;
12488 START_FOLD_INIT;
12492 END_FOLD_INIT;
12494 }
12496 tree
12499 {
12500 tree result;
12501 START_FOLD_INIT;
12505 END_FOLD_INIT;
12507 }
12509 #undef START_FOLD_INIT
12510 #undef END_FOLD_INIT
12512 /* Determine if first argument is a multiple of second argument. Return 0 if
12513 it is not, or we cannot easily determined it to be.
12515 An example of the sort of thing we care about (at this point; this routine
12516 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12517 fold cases do now) is discovering that
12519 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12521 is a multiple of
12523 SAVE_EXPR (J * 8)
12525 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12527 This code also handles discovering that
12529 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12531 is a multiple of 8 so we don't have to worry about dealing with a
12532 possible remainder.
12534 Note that we *look* inside a SAVE_EXPR only to determine how it was
12535 calculated; it is not safe for fold to do much of anything else with the
12536 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12537 at run time. For example, the latter example above *cannot* be implemented
12538 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12539 evaluation time of the original SAVE_EXPR is not necessarily the same at
12540 the time the new expression is evaluated. The only optimization of this
12541 sort that would be valid is changing
12543 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12545 divided by 8 to
12547 SAVE_EXPR (I) * SAVE_EXPR (J)
12549 (where the same SAVE_EXPR (J) is used in the original and the
12550 transformed version). */
12552 int
12554 {
12565 {
12567 /* Bitwise and provides a power of two multiple. If the mask is
12568 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12571 /* FALLTHRU */
12578 /* It is impossible to prove if op0 - op1 is multiple of bottom
12579 precisely, so be conservative here checking if both op0 and op1
12580 are multiple of bottom. Note we check the second operand first
12581 since it's usually simpler. */
12586 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12587 as op0 - 3 if the expression has unsigned type. For example,
12588 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12598 {
12600 /* const_binop may not detect overflow correctly,
12601 so check for it explicitly here. */
12605 size_one_node,
12606 op1)))
12609 }
12613 /* Can't handle conversions from non-integral or wider integral type. */
12619 /* fall through */
12636 SIGNED);
12642 {
12645 /* Check for special cases to see if top is defined as multiple
12646 of bottom:
12648 top = (X & ~(bottom - 1) ; bottom is power of 2
12650 or
12652 Y = X % bottom
12653 top = X - Y. */
12672 }
12674 /* fall through */
12678 }
12679 }
12681 #define tree_expr_nonnegative_warnv_p(X, Y) \
12684 #define RECURSE(X) \
12685 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12687 /* Return true if CODE or TYPE is known to be non-negative. */
12689 static bool
12691 {
12694 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12695 have a signed:1 type (where the value is -1 and 0). */
12698 }
12700 /* Return true if (CODE OP0) is known to be non-negative. If the return
12701 value is based on the assumption that signed overflow is undefined,
12702 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12703 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12705 bool
12708 {
12713 {
12715 /* We can't return 1 if flag_wrapv is set because
12716 ABS_EXPR<INT_MIN> = INT_MIN. */
12720 {
12723 }
12731 CASE_CONVERT:
12732 {
12737 {
12741 {
12745 }
12746 }
12748 {
12754 }
12755 }
12760 }
12762 /* We don't know sign of `t', so be conservative and return false. */
12764 }
12766 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12767 value is based on the assumption that signed overflow is undefined,
12768 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12769 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12771 bool
12775 {
12780 {
12786 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12787 both unsigned and at least 2 bits shorter than the result. */
12791 {
12796 {
12800 }
12801 }
12806 {
12807 /* x * x is always non-negative for floating point x
12808 or without overflow. */
12811 {
12816 }
12817 }
12819 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12820 both unsigned and their total bits is shorter than the result. */
12824 {
12843 {
12853 }
12854 }
12881 }
12883 /* We don't know sign of `t', so be conservative and return false. */
12885 }
12887 /* Return true if T is known to be non-negative. If the return
12888 value is based on the assumption that signed overflow is undefined,
12889 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12890 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12892 bool
12894 {
12899 {
12913 /* Limit the depth of recursion to avoid quadratic behavior.
12914 This is expected to catch almost all occurrences in practice.
12915 If this code misses important cases that unbounded recursion
12916 would not, passes that need this information could be revised
12917 to provide it through dataflow propagation. */
12925 }
12926 }
12928 /* Return true if T is known to be non-negative. If the return
12929 value is based on the assumption that signed overflow is undefined,
12930 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12931 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12933 bool
12936 {
12938 {
12939 CASE_CFN_ACOS:
12940 CASE_CFN_ACOSH:
12941 CASE_CFN_CABS:
12942 CASE_CFN_COSH:
12943 CASE_CFN_ERFC:
12944 CASE_CFN_EXP:
12945 CASE_CFN_EXP10:
12946 CASE_CFN_EXP2:
12947 CASE_CFN_FABS:
12948 CASE_CFN_FDIM:
12949 CASE_CFN_HYPOT:
12950 CASE_CFN_POW10:
12951 CASE_CFN_FFS:
12952 CASE_CFN_PARITY:
12953 CASE_CFN_POPCOUNT:
12954 CASE_CFN_CLZ:
12955 CASE_CFN_CLRSB:
12958 /* Always true. */
12961 CASE_CFN_SQRT:
12962 /* sqrt(-0.0) is -0.0. */
12967 CASE_CFN_ASINH:
12968 CASE_CFN_ATAN:
12969 CASE_CFN_ATANH:
12970 CASE_CFN_CBRT:
12971 CASE_CFN_CEIL:
12972 CASE_CFN_ERF:
12973 CASE_CFN_EXPM1:
12974 CASE_CFN_FLOOR:
12975 CASE_CFN_FMOD:
12976 CASE_CFN_FREXP:
12977 CASE_CFN_ICEIL:
12978 CASE_CFN_IFLOOR:
12979 CASE_CFN_IRINT:
12980 CASE_CFN_IROUND:
12981 CASE_CFN_LCEIL:
12982 CASE_CFN_LDEXP:
12983 CASE_CFN_LFLOOR:
12984 CASE_CFN_LLCEIL:
12985 CASE_CFN_LLFLOOR:
12986 CASE_CFN_LLRINT:
12987 CASE_CFN_LLROUND:
12988 CASE_CFN_LRINT:
12989 CASE_CFN_LROUND:
12990 CASE_CFN_MODF:
12991 CASE_CFN_NEARBYINT:
12992 CASE_CFN_RINT:
12993 CASE_CFN_ROUND:
12994 CASE_CFN_SCALB:
12995 CASE_CFN_SCALBLN:
12996 CASE_CFN_SCALBN:
12997 CASE_CFN_SIGNBIT:
12998 CASE_CFN_SIGNIFICAND:
12999 CASE_CFN_SINH:
13000 CASE_CFN_TANH:
13001 CASE_CFN_TRUNC:
13002 /* True if the 1st argument is nonnegative. */
13005 CASE_CFN_FMAX:
13006 /* True if the 1st OR 2nd arguments are nonnegative. */
13009 CASE_CFN_FMIN:
13010 /* True if the 1st AND 2nd arguments are nonnegative. */
13013 CASE_CFN_COPYSIGN:
13014 /* True if the 2nd argument is nonnegative. */
13017 CASE_CFN_POWI:
13018 /* True if the 1st argument is nonnegative or the second
13019 argument is an even integer. */
13025 CASE_CFN_POW:
13026 /* True if the 1st argument is nonnegative or the second
13027 argument is an even integer valued real. */
13029 {
13030 REAL_VALUE_TYPE c;
13031 HOST_WIDE_INT n;
13036 {
13037 REAL_VALUE_TYPE cint;
13041 }
13042 }
13047 }
13049 }
13051 /* Return true if T is known to be non-negative. If the return
13052 value is based on the assumption that signed overflow is undefined,
13053 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13054 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13056 static bool
13058 {
13064 {
13066 {
13070 /* If the initializer is non-void, then it's a normal expression
13071 that will be assigned to the slot. */
13075 /* Otherwise, the initializer sets the slot in some way. One common
13076 way is an assignment statement at the end of the initializer. */
13078 {
13086 else
13088 }
13094 }
13097 {
13103 arg0,
13104 arg1,
13106 }
13119 }
13120 }
13122 #undef RECURSE
13123 #undef tree_expr_nonnegative_warnv_p
13125 /* Return true if T is known to be non-negative. If the return
13126 value is based on the assumption that signed overflow is undefined,
13127 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13128 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13130 bool
13132 {
13139 {
13161 }
13164 {
13190 }
13191 }
13193 /* Return true if `t' is known to be non-negative. Handle warnings
13194 about undefined signed overflow. */
13196 bool
13198 {
13205 "determining that expression is always "
13207 WARN_STRICT_OVERFLOW_MISC);
13209 }
13212 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13213 For floating point we further ensure that T is not denormal.
13214 Similar logic is present in nonzero_address in rtlanal.h.
13216 If the return value is based on the assumption that signed overflow
13217 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13218 change *STRICT_OVERFLOW_P. */
13220 bool
13223 {
13225 {
13228 strict_overflow_p);
13231 {
13237 strict_overflow_p));
13238 }
13243 strict_overflow_p);
13247 }
13250 }
13252 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13253 For floating point we further ensure that T is not denormal.
13254 Similar logic is present in nonzero_address in rtlanal.h.
13256 If the return value is based on the assumption that signed overflow
13257 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13258 change *STRICT_OVERFLOW_P. */
13260 bool
13262 tree type,
13263 tree op0,
13265 {
13268 {
13272 {
13273 /* With the presence of negative values it is hard
13274 to say something. */
13281 /* One of operands must be positive and the other non-negative. */
13282 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13283 overflows, on a twos-complement machine the sum of two
13284 nonnegative numbers can never be zero. */
13286 strict_overflow_p)
13288 strict_overflow_p));
13289 }
13294 {
13296 strict_overflow_p)
13298 strict_overflow_p))
13299 {
13302 }
13303 }
13312 {
13315 }
13322 {
13326 /* When both operands are nonzero, then MAX must be too. */
13328 strict_overflow_p))
13331 /* MAX where operand 0 is positive is positive. */
13333 strict_overflow_p);
13334 }
13335 /* MAX where operand 1 is positive is positive. */
13340 {
13344 }
13349 strict_overflow_p)
13351 strict_overflow_p));
13355 }
13358 }
13360 /* Return true when T is an address and is known to be nonzero.
13361 For floating point we further ensure that T is not denormal.
13362 Similar logic is present in nonzero_address in rtlanal.h.
13364 If the return value is based on the assumption that signed overflow
13365 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13366 change *STRICT_OVERFLOW_P. */
13368 bool
13370 {
13373 {
13378 {
13390 /* For objects in symbol table check if we know they are non-zero.
13391 Don't do anything for variables and functions before symtab is built;
13392 it is quite possible that they will be declared weak later. */
13397 /* Function local objects are never NULL. */
13404 /* Constants are never weak. */
13409 }
13417 {
13421 }
13426 }
13428 }
13430 #define integer_valued_real_p(X) \
13433 #define RECURSE(X) \
13434 ((integer_valued_real_p) (X, depth + 1))
13436 /* Return true if the floating point result of (CODE OP0) has an
13437 integer value. We also allow +Inf, -Inf and NaN to be considered
13438 integer values. Return false for signaling NaN.
13440 DEPTH is the current nesting depth of the query. */
13442 bool
13444 {
13446 {
13453 CASE_CONVERT:
13454 {
13461 }
13465 }
13467 }
13469 /* Return true if the floating point result of (CODE OP0 OP1) has an
13470 integer value. We also allow +Inf, -Inf and NaN to be considered
13471 integer values. Return false for signaling NaN.
13473 DEPTH is the current nesting depth of the query. */
13475 bool
13477 {
13479 {
13489 }
13491 }
13493 /* Return true if the floating point result of calling FNDECL with arguments
13494 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13495 considered integer values. Return false for signaling NaN. If FNDECL
13496 takes fewer than 2 arguments, the remaining ARGn are null.
13498 DEPTH is the current nesting depth of the query. */
13500 bool
13502 {
13504 {
13505 CASE_CFN_CEIL:
13506 CASE_CFN_FLOOR:
13507 CASE_CFN_NEARBYINT:
13508 CASE_CFN_RINT:
13509 CASE_CFN_ROUND:
13510 CASE_CFN_TRUNC:
13513 CASE_CFN_FMIN:
13514 CASE_CFN_FMAX:
13519 }
13521 }
13523 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13524 has an integer value. We also allow +Inf, -Inf and NaN to be
13525 considered integer values. Return false for signaling NaN.
13527 DEPTH is the current nesting depth of the query. */
13529 bool
13531 {
13533 {
13541 /* Limit the depth of recursion to avoid quadratic behavior.
13542 This is expected to catch almost all occurrences in practice.
13543 If this code misses important cases that unbounded recursion
13544 would not, passes that need this information could be revised
13545 to provide it through dataflow propagation. */
13549 depth));
13553 }
13555 }
13557 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13558 has an integer value. We also allow +Inf, -Inf and NaN to be
13559 considered integer values. Return false for signaling NaN.
13561 DEPTH is the current nesting depth of the query. */
13563 static bool
13565 {
13567 {
13578 }
13580 }
13582 #undef RECURSE
13583 #undef integer_valued_real_p
13585 /* Return true if the floating point expression T has an integer value.
13586 We also allow +Inf, -Inf and NaN to be considered integer values.
13587 Return false for signaling NaN.
13589 DEPTH is the current nesting depth of the query. */
13591 bool
13593 {
13599 {
13615 }
13618 {
13624 {
13633 }
13637 }
13638 }
13640 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13641 attempt to fold the expression to a constant without modifying TYPE,
13642 OP0 or OP1.
13644 If the expression could be simplified to a constant, then return
13645 the constant. If the expression would not be simplified to a
13646 constant, then return NULL_TREE. */
13648 tree
13650 {
13653 }
13655 /* Given the components of a unary expression CODE, TYPE and OP0,
13656 attempt to fold the expression to a constant without modifying
13657 TYPE or OP0.
13659 If the expression could be simplified to a constant, then return
13660 the constant. If the expression would not be simplified to a
13661 constant, then return NULL_TREE. */
13663 tree
13665 {
13668 }
13670 /* If EXP represents referencing an element in a constant string
13671 (either via pointer arithmetic or array indexing), return the
13672 tree representing the value accessed, otherwise return NULL. */
13674 tree
13676 {
13680 {
13682 tree index;
13683 tree string;
13688 else
13689 {
13693 /* Optimize the special-case of a zero lower bound.
13695 We convert the low_bound to sizetype to avoid some problems
13696 with constant folding. (E.g. suppose the lower bound is 1,
13697 and its mode is QI. Without the conversion,l (ARRAY
13698 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13699 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13705 }
13718 }
13720 }
13722 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13723 an integer constant, real, or fixed-point constant.
13725 TYPE is the type of the result. */
13727 static tree
13729 {
13733 {
13735 {
13742 }
13749 {
13750 FIXED_VALUE_TYPE f;
13755 /* Propagate overflow flags. */
13759 }
13763 }
13766 }
13768 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13769 an integer constant or real constant.
13771 TYPE is the type of the result. */
13773 tree
13775 {
13779 {
13781 {
13782 /* If the value is unsigned or non-negative, then the absolute value
13783 is the same as the ordinary value. */
13787 /* If the value is negative, then the absolute value is
13788 its negation. */
13789 else
13790 {
13795 }
13796 }
13802 else
13808 }
13811 }
13813 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13814 constant. TYPE is the type of the result. */
13816 static tree
13818 {
13822 }
13824 /* Given CODE, a relational operator, the target type, TYPE and two
13825 constant operands OP0 and OP1, return the result of the
13826 relational operation. If the result is not a compile time
13827 constant, then return NULL_TREE. */
13829 static tree
13831 {
13834 /* From here on, the only cases we handle are when the result is
13835 known to be a constant. */
13838 {
13842 /* Handle the cases where either operand is a NaN. */
13844 {
13846 {
13874 }
13877 }
13880 }
13883 {
13887 }
13889 /* Handle equality/inequality of complex constants. */
13891 {
13902 else
13904 }
13907 {
13909 {
13910 /* Have vector comparison with scalar boolean result. */
13914 {
13922 }
13924 }
13931 {
13943 }
13946 }
13948 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13950 To compute GT, swap the arguments and do LT.
13951 To compute GE, do LT and invert the result.
13952 To compute LE, swap the arguments, do LT and invert the result.
13953 To compute NE, do EQ and invert the result.
13955 Therefore, the code below must handle only EQ and LT. */
13958 {
13961 }
13963 /* Note that it is safe to invert for real values here because we
13964 have already handled the one case that it matters. */
13968 {
13971 }
13973 /* Compute a result for LT or EQ if args permit;
13974 Otherwise return T. */
13976 {
13979 else
13981 }
13982 else
13988 }
13990 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13991 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13992 itself. */
13994 tree
13996 {
13997 /* If the expression does not have side effects then we don't have to wrap
13998 it with a cleanup point expression. */
14002 /* If the expression is a return, check to see if the expression inside the
14003 return has no side effects or the right hand side of the modify expression
14004 inside the return. If either don't have side effects set we don't need to
14005 wrap the expression in a cleanup point expression. Note we don't check the
14006 left hand side of the modify because it should always be a return decl. */
14008 {
14015 }
14018 }
14020 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14021 of an indirection through OP0, or NULL_TREE if no simplification is
14022 possible. */
14024 tree
14026 {
14028 tree subtype;
14036 {
14039 /* *&CONST_DECL -> to the value of the const decl. */
14042 /* *&p => p; make sure to handle *&"str"[cst] here. */
14044 {
14048 else
14050 }
14051 /* *(foo *)&fooarray => fooarray[0] */
14054 && (!in_gimple_form
14056 {
14066 }
14067 /* *(foo *)&complexfoo => __real__ complexfoo */
14071 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14074 {
14078 }
14079 }
14083 {
14089 {
14090 tree op00type;
14094 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14097 {
14099 unsigned HOST_WIDE_INT max_offset
14104 {
14111 }
14112 }
14113 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14116 {
14120 }
14121 /* ((foo *)&fooarray)[1] => fooarray[1] */
14124 {
14134 }
14135 }
14136 }
14138 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14141 && (!in_gimple_form
14143 {
14144 tree type_domain;
14154 NULL_TREE);
14155 }
14158 }
14160 /* Builds an expression for an indirection through T, simplifying some
14161 cases. */
14163 tree
14165 {
14173 }
14175 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14177 tree
14179 {
14184 else
14186 }
14188 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14189 whose result is ignored. The type of the returned tree need not be
14190 the same as the original expression. */
14192 tree
14194 {
14200 {
14211 else
14217 {
14233 }
14238 }
14239 }
14241 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14243 tree
14245 {
14251 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14252 have to do anything. Only do this when we are not given a const,
14253 because in that case, this check is more expensive than just
14254 doing it. */
14256 {
14261 }
14263 /* If divisor is a power of two, simplify this to bit manipulation. */
14265 {
14267 {
14281 }
14282 else
14283 {
14284 tree t;
14290 }
14291 }
14292 else
14293 {
14298 }
14301 }
14303 /* Likewise, but round down. */
14305 tree
14307 {
14314 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14315 have to do anything. Only do this when we are not given a const,
14316 because in that case, this check is more expensive than just
14317 doing it. */
14319 {
14324 }
14326 /* If divisor is a power of two, simplify this to bit manipulation. */
14328 {
14329 tree t;
14333 }
14334 else
14335 {
14340 }
14343 }
14345 /* Returns the pointer to the base of the object addressed by EXP and
14346 extracts the information about the offset of the access, storing it
14347 to PBITPOS and POFFSET. */
14349 static tree
14352 {
14353 tree core;
14354 machine_mode mode;
14356 HOST_WIDE_INT bitsize;
14360 {
14365 }
14366 else
14367 {
14371 }
14374 }
14376 /* Returns true if addresses of E1 and E2 differ by a constant, false
14377 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14379 bool
14381 {
14395 {
14405 }
14407 {
14408 /* If only one of the offsets is non-constant, the difference cannot
14409 be a constant. */
14411 }
14412 else
14417 }
14419 /* Return OFF converted to a pointer offset type suitable as offset for
14420 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14421 tree
14423 {
14425 }
14427 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14428 tree
14430 {
14433 }
14435 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14436 tree
14438 {
14441 }
14443 /* Return a char pointer for a C string if it is a string constant
14444 or sum of string constant and integer constant. We only support
14445 string constants properly terminated with '\0' character.
14446 If STRLEN is a valid pointer, length (including terminating character)
14447 of returned string is stored to the argument. */
14451 {
14452 tree offset_node;
14463 {
14466 else
14468 }
14473 /* Support only properly null-terminated strings. */
14482 }
14484 #if CHECKING_P
14488 /* Helper functions for writing tests of folding trees. */
14490 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14492 static void
14494 tree constant)
14495 {
14497 }
14499 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14500 wrapping WRAPPED_EXPR. */
14502 static void
14504 tree wrapped_expr)
14505 {
14510 }
14512 /* Verify that various arithmetic binary operations are folded
14513 correctly. */
14515 static void
14517 {
14523 /* Addition. */
14524 /* 1 <-- (0 + 1) */
14526 one);
14528 one);
14530 /* (nonlvalue)x <-- (x + 0) */
14532 x);
14534 /* Subtraction. */
14535 /* 0 <-- (x - x) */
14537 zero);
14539 x);
14541 /* Multiplication. */
14542 /* 0 <-- (x * 0) */
14544 zero);
14546 /* (nonlvalue)x <-- (x * 1) */
14548 x);
14549 }
14551 /* Verify that various binary operations on vectors are folded
14552 correctly. */
14554 static void
14556 {
14562 /* Verify equality tests that return a scalar boolean result. */
14568 }
14570 /* Run all of the selftests within this file. */
14572 void
14574 {
14577 }