| blob | 8974dc0b91a1bda7ac1d8d45be0c89d576785018 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2015 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. */
103 /* Nonzero if we are folding constants inside an initializer; zero
104 otherwise. */
107 /* The following constants represent a bit based encoding of GCC's
108 comparison operators. This encoding simplifies transformations
109 on relational comparison operators, such as AND and OR. */
127 };
145 HOST_WIDE_INT *,
178 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
179 Otherwise, return LOC. */
181 static location_t
183 {
186 }
188 /* Similar to protected_set_expr_location, but never modify x in place,
189 if location can and needs to be set, unshare it. */
193 {
199 {
202 }
204 }
205 \f
206 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
207 division and returns the quotient. Otherwise returns
208 NULL_TREE. */
210 tree
212 {
213 widest_int quo;
220 }
221 \f
222 /* This is nonzero if we should defer warnings about undefined
223 overflow. This facility exists because these warnings are a
224 special case. The code to estimate loop iterations does not want
225 to issue any warnings, since it works with expressions which do not
226 occur in user code. Various bits of cleanup code call fold(), but
227 only use the result if it has certain characteristics (e.g., is a
228 constant); that code only wants to issue a warning if the result is
229 used. */
233 /* If a warning about undefined overflow is deferred, this is the
234 warning. Note that this may cause us to turn two warnings into
235 one, but that is fine since it is sufficient to only give one
236 warning per expression. */
240 /* If a warning about undefined overflow is deferred, this is the
241 level at which the warning should be emitted. */
245 /* Start deferring overflow warnings. We could use a stack here to
246 permit nested calls, but at present it is not necessary. */
248 void
250 {
252 }
254 /* Stop deferring overflow warnings. If there is a pending warning,
255 and ISSUE is true, then issue the warning if appropriate. STMT is
256 the statement with which the warning should be associated (used for
257 location information); STMT may be NULL. CODE is the level of the
258 warning--a warn_strict_overflow_code value. This function will use
259 the smaller of CODE and the deferred code when deciding whether to
260 issue the warning. CODE may be zero to mean to always use the
261 deferred code. */
263 void
265 {
267 location_t locus;
272 {
278 }
289 /* Use the smallest code level when deciding to issue the
290 warning. */
299 else
302 }
304 /* Stop deferring overflow warnings, ignoring any deferred
305 warnings. */
307 void
309 {
311 }
313 /* Whether we are deferring overflow warnings. */
315 bool
317 {
319 }
321 /* This is called when we fold something based on the fact that signed
322 overflow is undefined. */
324 static void
326 {
328 {
331 {
334 }
335 }
338 }
339 \f
340 /* Return true if the built-in mathematical function specified by CODE
341 is odd, i.e. -f(x) == f(-x). */
343 static bool
345 {
347 {
381 }
383 }
385 /* Check whether we may negate an integer constant T without causing
386 overflow. */
388 bool
390 {
391 tree type;
400 }
402 /* Determine whether an expression T can be cheaply negated using
403 the function negate_expr without introducing undefined overflow. */
405 static bool
407 {
408 tree type;
417 {
422 /* Check that -CST will not overflow type. */
435 /* We want to canonicalize to positive real constants. Pretend
436 that only negative ones can be easily negated. */
444 {
455 }
468 /* -(A + B) -> (-B) - A. */
473 /* -(A + B) -> (-A) - B. */
477 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
487 /* Fall through. */
498 /* In general we can't negate A / B, because if A is INT_MIN and
499 B is 1, we may turn this into INT_MIN / -1 which is undefined
500 and actually traps on some architectures. But if overflow is
501 undefined, we can negate, because - (INT_MIN / 1) is an
502 overflow. */
504 {
507 /* If overflow is undefined then we have to be careful because
508 we ask whether it's ok to associate the negate with the
509 division which is not ok for example for
510 -((a - b) / c) where (-(a - b)) / c may invoke undefined
511 overflow because of negating INT_MIN. So do not use
512 negate_expr_p here but open-code the two important cases. */
517 }
523 /* Negate -((double)float) as (double)(-float). */
525 {
529 }
533 /* Negate -f(x) as f(-x). */
539 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
541 {
545 }
550 }
552 }
554 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
555 simplification is possible.
556 If negate_expr_p would return true for T, NULL_TREE will never be
557 returned. */
559 static tree
561 {
563 tree tem;
566 {
567 /* Convert - (~A) to A + 1. */
593 {
598 }
602 {
607 {
611 }
614 }
637 {
638 /* -(A + B) -> (-B) - A. */
642 {
646 }
648 /* -(A + B) -> (-A) - B. */
650 {
654 }
655 }
659 /* - (A - B) -> B - A */
671 /* Fall through. */
675 {
684 }
690 /* In general we can't negate A / B, because if A is INT_MIN and
691 B is 1, we may turn this into INT_MIN / -1 which is undefined
692 and actually traps on some architectures. But if overflow is
693 undefined, we can negate, because - (INT_MIN / 1) is an
694 overflow. */
696 {
701 {
708 }
709 /* If overflow is undefined then we have to be careful because
710 we ask whether it's ok to associate the negate with the
711 division which is not ok for example for
712 -((a - b) / c) where (-(a - b)) / c may invoke undefined
713 overflow because of negating INT_MIN. So do not use
714 negate_expr_p here but open-code the two important cases. */
723 }
727 /* Convert -((double)float) into (double)(-float). */
729 {
733 }
737 /* Negate -f(x) as f(-x). */
740 {
746 }
750 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
752 {
755 {
762 }
763 }
768 }
771 }
773 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
774 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
775 return NULL_TREE. */
777 static tree
779 {
781 location_t loc;
794 }
795 \f
796 /* Split a tree IN into a constant, literal and variable parts that could be
797 combined with CODE to make IN. "constant" means an expression with
798 TREE_CONSTANT but that isn't an actual constant. CODE must be a
799 commutative arithmetic operation. Store the constant part into *CONP,
800 the literal in *LITP and return the variable part. If a part isn't
801 present, set it to null. If the tree does not decompose in this way,
802 return the entire tree as the variable part and the other parts as null.
804 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
805 case, we negate an operand that was subtracted. Except if it is a
806 literal for which we use *MINUS_LITP instead.
808 If NEGATE_P is true, we are negating all of IN, again except a literal
809 for which we use *MINUS_LITP instead.
811 If IN is itself a literal or constant, return it as appropriate.
813 Note that we do not guarantee that any of the three values will be the
814 same type as IN, but they will have the same signedness and mode. */
816 static tree
819 {
826 /* Strip any conversions that don't change the machine mode or signedness. */
835 /* We can associate addition and subtraction together (even
836 though the C standard doesn't say so) for integers because
837 the value is not affected. For reals, the value might be
838 affected, so we can't. */
841 {
847 /* First see if either of the operands is a literal, then a constant. */
860 /* If we haven't dealt with either operand, this is not a case we can
861 decompose. Otherwise, VAR is either of the ones remaining, if any. */
866 else
869 /* Now do any needed negations. */
876 }
879 {
880 /* -X - 1 is folded to ~X, undo that here. */
883 }
886 else
890 {
897 }
900 }
902 /* Re-associate trees split by the above function. T1 and T2 are
903 either expressions to associate or null. Return the new
904 expression, if any. LOC is the location of the new expression. If
905 we build an operation, do it in TYPE and with CODE. */
907 static tree
909 {
915 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
916 try to fold this since we will have infinite recursion. But do
917 deal with any NEGATE_EXPRs. */
920 {
922 {
935 }
937 {
940 }
944 }
948 }
949 \f
950 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
951 for use in int_const_binop, size_binop and size_diffop. */
953 static bool
955 {
962 {
971 }
976 }
979 /* Combine two integer constants ARG1 and ARG2 under operation CODE
980 to produce a new constant. Return NULL_TREE if we don't know how
981 to evaluate CODE at compile-time. */
983 static tree
986 {
987 wide_int res;
988 tree t;
997 {
1013 {
1017 else
1019 }
1022 /* It's unclear from the C standard whether shifts can overflow.
1023 The following code ignores overflow; perhaps a C standard
1024 interpretation ruling is needed. */
1026 else
1033 {
1037 else
1039 }
1043 else
1122 }
1130 }
1132 tree
1134 {
1136 }
1138 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1139 constant. We assume ARG1 and ARG2 have the same data type, or at least
1140 are the same kind of constant and the same machine mode. Return zero if
1141 combining the constants is not allowed in the current operating mode. */
1143 static tree
1145 {
1146 /* Sanity check for the recursive cases. */
1154 {
1160 }
1163 {
1164 machine_mode mode;
1165 REAL_VALUE_TYPE d1;
1166 REAL_VALUE_TYPE d2;
1167 REAL_VALUE_TYPE value;
1168 REAL_VALUE_TYPE result;
1172 /* The following codes are handled by real_arithmetic. */
1174 {
1185 }
1193 /* Don't perform operation if we honor signaling NaNs and
1194 either operand is a NaN. */
1199 /* Don't perform operation if it would raise a division
1200 by zero exception. */
1206 /* If either operand is a NaN, just return it. Otherwise, set up
1207 for floating-point trap; we return an overflow. */
1216 /* Don't constant fold this floating point operation if
1217 the result has overflowed and flag_trapping_math. */
1225 /* Don't constant fold this floating point operation if the
1226 result may dependent upon the run-time rounding mode and
1227 flag_rounding_math is set, or if GCC's software emulation
1228 is unable to accurately represent the result. */
1238 }
1241 {
1242 FIXED_VALUE_TYPE f1;
1243 FIXED_VALUE_TYPE f2;
1244 FIXED_VALUE_TYPE result;
1249 /* The following codes are handled by fixed_arithmetic. */
1251 {
1263 {
1270 }
1275 }
1282 /* Propagate overflow flags. */
1286 }
1289 {
1298 {
1309 mpc_mul);
1323 mpc_div);
1324 /* Fallthru ... */
1330 {
1331 /* Keep this algorithm in sync with
1332 tree-complex.c:expand_complex_div_straight().
1334 Expand complex division to scalars, straightforward algorithm.
1335 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1336 t = br*br + bi*bi
1337 */
1338 tree magsquared
1342 tree t1
1346 tree t2
1353 }
1354 else
1355 {
1356 /* Keep this algorithm in sync with
1357 tree-complex.c:expand_complex_div_wide().
1359 Expand complex division to scalars, modified algorithm to minimize
1360 overflow with wide input ranges. */
1366 {
1367 /* In the TRUE branch, we compute
1368 ratio = br/bi;
1369 div = (br * ratio) + bi;
1370 tr = (ar * ratio) + ai;
1371 ti = (ai * ratio) - ar;
1372 tr = tr / div;
1373 ti = ti / div; */
1384 }
1385 else
1386 {
1387 /* In the FALSE branch, we compute
1388 ratio = d/c;
1389 divisor = (d * ratio) + c;
1390 tr = (b * ratio) + a;
1391 ti = b - (a * ratio);
1392 tr = tr / div;
1393 ti = ti / div; */
1405 }
1406 }
1411 }
1415 }
1419 {
1425 {
1431 /* It is possible that const_binop cannot handle the given
1432 code and return NULL_TREE */
1435 }
1438 }
1440 /* Shifts allow a scalar offset for a vector. */
1443 {
1449 {
1454 /* It is possible that const_binop cannot handle the given
1455 code and return NULL_TREE. */
1458 }
1461 }
1463 }
1465 /* Overload that adds a TYPE parameter to be able to dispatch
1466 to fold_relational_const. */
1468 tree
1470 {
1474 /* ??? Until we make the const_binop worker take the type of the
1475 result as argument put those cases that need it here. */
1477 {
1488 {
1504 {
1510 }
1513 }
1519 {
1544 {
1557 }
1560 }
1563 }
1565 /* Make sure type and arg0 have the same saturating flag. */
1569 }
1571 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1572 Return zero if computing the constants is not possible. */
1574 tree
1576 {
1578 {
1579 CASE_CONVERT:
1594 {
1595 /* Can't call fold_negate_const directly here as that doesn't
1596 handle all cases and we might not be able to negate some
1597 constants. */
1602 }
1611 {
1615 }
1621 /* Perform BIT_NOT_EXPR on each element individually. */
1623 {
1625 tree elem;
1630 {
1636 }
1639 }
1661 {
1680 else
1684 {
1688 }
1691 }
1696 {
1710 {
1715 }
1718 {
1722 }
1725 }
1729 }
1732 }
1734 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1735 indicates which particular sizetype to create. */
1737 tree
1739 {
1741 }
1742 \f
1743 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1744 is a tree code. The type of the result is taken from the operands.
1745 Both must be equivalent integer types, ala int_binop_types_match_p.
1746 If the operands are constant, so is the result. */
1748 tree
1750 {
1759 /* Handle the special case of two integer constants faster. */
1761 {
1762 /* And some specific cases even faster than that. */
1764 {
1769 }
1771 {
1774 }
1776 {
1779 }
1781 /* Handle general case of two integer constants. For sizetype
1782 constant calculations we always want to know about overflow,
1783 even in the unsigned case. */
1785 }
1788 }
1790 /* Given two values, either both of sizetype or both of bitsizetype,
1791 compute the difference between the two values. Return the value
1792 in signed type corresponding to the type of the operands. */
1794 tree
1796 {
1798 tree ctype;
1803 /* If the type is already signed, just do the simple thing. */
1811 else
1814 /* If either operand is not a constant, do the conversions to the signed
1815 type and subtract. The hardware will do the right thing with any
1816 overflow in the subtraction. */
1822 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1823 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1824 overflow) and negate (which can't either). Special-case a result
1825 of zero while we're here. */
1831 else
1835 MINUS_EXPR,
1837 }
1838 \f
1839 /* A subroutine of fold_convert_const handling conversions of an
1840 INTEGER_CST to another integer type. */
1842 static tree
1844 {
1845 /* Given an integer constant, make new constant with new type,
1846 appropriately sign-extended or truncated. Use widest_int
1847 so that any extension is done according ARG1's type. */
1851 }
1853 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1854 to an integer type. */
1856 static tree
1858 {
1860 tree t;
1862 /* The following code implements the floating point to integer
1863 conversion rules required by the Java Language Specification,
1864 that IEEE NaNs are mapped to zero and values that overflow
1865 the target precision saturate, i.e. values greater than
1866 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1867 are mapped to INT_MIN. These semantics are allowed by the
1868 C and C++ standards that simply state that the behavior of
1869 FP-to-integer conversion is unspecified upon overflow. */
1871 wide_int val;
1872 REAL_VALUE_TYPE r;
1876 {
1883 }
1885 /* If R is NaN, return zero and show we have an overflow. */
1887 {
1890 }
1892 /* See if R is less than the lower bound or greater than the
1893 upper bound. */
1896 {
1900 {
1903 }
1904 }
1907 {
1910 {
1913 {
1916 }
1917 }
1918 }
1925 }
1927 /* A subroutine of fold_convert_const handling conversions of a
1928 FIXED_CST to an integer type. */
1930 static tree
1932 {
1933 tree t;
1937 /* Right shift FIXED_CST to temp by fbit. */
1941 {
1943 HOST_BITS_PER_DOUBLE_INT,
1946 /* Left shift temp to temp_trunc by fbit. */
1948 HOST_BITS_PER_DOUBLE_INT,
1950 }
1951 else
1952 {
1955 }
1957 /* If FIXED_CST is negative, we need to round the value toward 0.
1958 By checking if the fractional bits are not zero to add 1 to temp. */
1964 /* Given a fixed-point constant, make new constant with new type,
1965 appropriately sign-extended or truncated. */
1973 }
1975 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1976 to another floating point type. */
1978 static tree
1980 {
1981 REAL_VALUE_TYPE value;
1982 tree t;
1987 /* If converting an infinity or NAN to a representation that doesn't
1988 have one, set the overflow bit so that we can produce some kind of
1989 error message at the appropriate point if necessary. It's not the
1990 most user-friendly message, but it's better than nothing. */
1997 /* Regular overflow, conversion produced an infinity in a mode that
1998 can't represent them. */
2003 else
2006 }
2008 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2009 to a floating point type. */
2011 static tree
2013 {
2014 REAL_VALUE_TYPE value;
2015 tree t;
2022 }
2024 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2025 to another fixed-point type. */
2027 static tree
2029 {
2030 FIXED_VALUE_TYPE value;
2031 tree t;
2038 /* Propagate overflow flags. */
2042 }
2044 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2045 to a fixed-point type. */
2047 static tree
2049 {
2050 FIXED_VALUE_TYPE value;
2051 tree t;
2053 double_int di;
2060 else
2068 /* Propagate overflow flags. */
2072 }
2074 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2075 to a fixed-point type. */
2077 static tree
2079 {
2080 FIXED_VALUE_TYPE value;
2081 tree t;
2089 /* Propagate overflow flags. */
2093 }
2095 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2096 type TYPE. If no simplification can be done return NULL_TREE. */
2098 static tree
2100 {
2106 {
2113 }
2115 {
2122 }
2124 {
2131 }
2133 }
2135 /* Construct a vector of zero elements of vector type TYPE. */
2137 static tree
2139 {
2140 tree t;
2144 }
2146 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2148 bool
2150 {
2165 {
2184 }
2185 }
2187 /* Convert expression ARG to type TYPE. Used by the middle-end for
2188 simple conversions in preference to calling the front-end's convert. */
2190 tree
2192 {
2194 tree tem;
2205 {
2208 /* Handle conversions between pointers to different address spaces. */
2213 /* fall through */
2218 {
2222 }
2236 {
2240 }
2242 {
2246 }
2248 {
2252 }
2255 {
2273 }
2278 {
2282 }
2285 {
2299 }
2303 {
2312 integer_zero_node));
2314 {
2318 {
2324 }
2332 }
2336 }
2354 }
2355 fold_convert_exit:
2358 }
2359 \f
2360 /* Return false if expr can be assumed not to be an lvalue, true
2361 otherwise. */
2363 static bool
2365 {
2366 /* We only need to wrap lvalue tree codes. */
2368 {
2399 /* Assume the worst for front-end tree codes. */
2403 }
2406 }
2408 /* Return an expr equal to X but certainly not valid as an lvalue. */
2410 tree
2412 {
2413 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2414 us. */
2421 }
2423 /* When pedantic, return an expr equal to X but certainly not valid as a
2424 pedantic lvalue. Otherwise, return X. */
2426 static tree
2428 {
2430 }
2431 \f
2432 /* Given a tree comparison code, return the code that is the logical inverse.
2433 It is generally not safe to do this for floating-point comparisons, except
2434 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2435 ERROR_MARK in this case. */
2437 enum tree_code
2439 {
2445 {
2476 }
2477 }
2479 /* Similar, but return the comparison that results if the operands are
2480 swapped. This is safe for floating-point. */
2482 enum tree_code
2484 {
2486 {
2512 }
2513 }
2516 /* Convert a comparison tree code from an enum tree_code representation
2517 into a compcode bit-based encoding. This function is the inverse of
2518 compcode_to_comparison. */
2520 static enum comparison_code
2522 {
2524 {
2555 }
2556 }
2558 /* Convert a compcode bit-based encoding of a comparison operator back
2559 to GCC's enum tree_code representation. This function is the
2560 inverse of comparison_to_compcode. */
2562 static enum tree_code
2564 {
2566 {
2597 }
2598 }
2600 /* Return a tree for the comparison which is the combination of
2601 doing the AND or OR (depending on CODE) of the two operations LCODE
2602 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2603 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2604 if this makes the transformation invalid. */
2606 tree
2611 {
2618 {
2629 }
2632 {
2633 /* Eliminate unordered comparisons, as well as LTGT and ORD
2634 which are not used unless the mode has NaNs. */
2640 }
2642 {
2643 /* Check that the original operation and the optimized ones will trap
2644 under the same condition. */
2655 /* In a short-circuited boolean expression the LHS might be
2656 such that the RHS, if evaluated, will never trap. For
2657 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2658 if neither x nor y is NaN. (This is a mixed blessing: for
2659 example, the expression above will never trap, hence
2660 optimizing it to x < y would be invalid). */
2665 /* If the comparison was short-circuited, and only the RHS
2666 trapped, we may now generate a spurious trap. */
2671 /* If we changed the conditions that cause a trap, we lose. */
2674 }
2680 else
2681 {
2686 }
2687 }
2688 \f
2689 /* Return nonzero if two operands (typically of the same tree node)
2690 are necessarily equal. If either argument has side-effects this
2691 function returns zero. FLAGS modifies behavior as follows:
2693 If OEP_ONLY_CONST is set, only return nonzero for constants.
2694 This function tests whether the operands are indistinguishable;
2695 it does not test whether they are equal using C's == operation.
2696 The distinction is important for IEEE floating point, because
2697 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2698 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2700 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2701 even though it may hold multiple values during a function.
2702 This is because a GCC tree node guarantees that nothing else is
2703 executed between the evaluation of its "operands" (which may often
2704 be evaluated in arbitrary order). Hence if the operands themselves
2705 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2706 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2707 unset means assuming isochronic (or instantaneous) tree equivalence.
2708 Unless comparing arbitrary expression trees, such as from different
2709 statements, this flag can usually be left unset.
2711 If OEP_PURE_SAME is set, then pure functions with identical arguments
2712 are considered the same. It is used when the caller has other ways
2713 to ensure that global memory is unchanged in between. */
2715 int
2717 {
2718 /* If either is ERROR_MARK, they aren't equal. */
2724 /* Similar, if either does not have a type (like a released SSA name),
2725 they aren't equal. */
2729 /* Check equality of integer constants before bailing out due to
2730 precision differences. */
2734 /* If both types don't have the same signedness, then we can't consider
2735 them equal. We must check this before the STRIP_NOPS calls
2736 because they may change the signedness of the arguments. As pointers
2737 strictly don't have a signedness, require either two pointers or
2738 two non-pointers as well. */
2743 /* We cannot consider pointers to different address space equal. */
2749 /* If both types don't have the same precision, then it is not safe
2750 to strip NOPs. */
2758 /* In case both args are comparisons but with different comparison
2759 code, try to swap the comparison operands of one arg to produce
2760 a match and compare that variant. */
2764 {
2772 }
2775 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2779 /* This is needed for conversions and for COMPONENT_REF.
2780 Might as well play it safe and always test this. */
2786 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2787 We don't care about side effects in that case because the SAVE_EXPR
2788 takes care of that for us. In all other cases, two expressions are
2789 equal if they have no side effects. If we have two identical
2790 expressions with side effects that should be treated the same due
2791 to the only side effects being identical SAVE_EXPR's, that will
2792 be detected in the recursive calls below.
2793 If we are taking an invariant address of two identical objects
2794 they are necessarily equal as well. */
2801 /* Next handle constant cases, those for which we can return 1 even
2802 if ONLY_CONST is set. */
2805 {
2820 {
2821 /* If we do not distinguish between signed and unsigned zero,
2822 consider them equal. */
2825 }
2829 {
2836 {
2840 }
2842 }
2846 flags)
2848 flags));
2862 }
2867 /* Define macros to test an operand from arg0 and arg1 for equality and a
2868 variant that allows null and views null as being different from any
2869 non-null value. In the latter case, if either is null, the both
2870 must be; otherwise, do the normal comparison. */
2871 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2872 TREE_OPERAND (arg1, N), flags)
2874 #define OP_SAME_WITH_NULL(N) \
2875 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2876 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2879 {
2881 /* Two conversions are equal only if signedness and modes match. */
2883 {
2884 CASE_CONVERT:
2892 }
2902 /* For commutative ops, allow the other order. */
2910 /* If either of the pointer (or reference) expressions we are
2911 dereferencing contain a side effect, these cannot be equal,
2912 but their addresses can be. */
2919 {
2930 /* Require equal extra operands and then fall through to MEM_REF
2931 handling of the two common operands. */
2936 /* Fallthru. */
2939 /* Require equal access sizes, and similar pointer types.
2940 We can have incomplete types for array references of
2941 variable-sized arrays from the Fortran frontend
2942 though. Also verify the types are compatible. */
2949 && alias_ptr_types_compatible_p
2956 /* Operands 2 and 3 may be null.
2957 Compare the array index by value if it is constant first as we
2958 may have different types but same value here. */
2969 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2970 may be NULL when we're called to compare MEM_EXPRs. */
2985 }
2989 {
3003 /* The multiplcation operands are commutative. */
3004 /* FALLTHRU */
3012 /* Otherwise take into account this is a commutative operation. */
3025 }
3029 {
3031 /* If the CALL_EXPRs call different functions, then they
3032 clearly can not be equal. */
3034 flags))
3037 {
3041 else
3045 }
3047 /* Now see if all the arguments are the same. */
3048 {
3059 /* If we get here and both argument lists are exhausted
3060 then the CALL_EXPRs are equal. */
3062 }
3065 }
3068 /* Consider __builtin_sqrt equal to sqrt. */
3076 }
3078 #undef OP_SAME
3079 #undef OP_SAME_WITH_NULL
3080 }
3081 \f
3082 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3083 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3085 When in doubt, return 0. */
3087 static int
3089 {
3101 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3102 and see if the inner values are the same. This removes any
3103 signedness comparison, which doesn't matter here. */
3110 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3111 actual comparison operand, ARG0.
3113 First throw away any conversions to wider types
3114 already present in the operands. */
3123 {
3126 /* Make sure shorter operand is extended the right way
3127 to match the longer operand. */
3133 }
3136 }
3137 \f
3138 /* See if ARG is an expression that is either a comparison or is performing
3139 arithmetic on comparisons. The comparisons must only be comparing
3140 two different values, which will be stored in *CVAL1 and *CVAL2; if
3141 they are nonzero it means that some operands have already been found.
3142 No variables may be used anywhere else in the expression except in the
3143 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3144 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3146 If this is true, return 1. Otherwise, return zero. */
3148 static int
3150 {
3154 /* We can handle some of the tcc_expression cases here. */
3164 {
3165 /* If we've already found a CVAL1 or CVAL2, this expression is
3166 two complex to handle. */
3172 }
3175 {
3198 /* First see if we can handle the first operand, then the second. For
3199 the second operand, we know *CVAL1 can't be zero. It must be that
3200 one side of the comparison is each of the values; test for the
3201 case where this isn't true by failing if the two operands
3202 are the same. */
3211 ;
3215 ;
3216 else
3220 ;
3224 ;
3225 else
3232 }
3233 }
3234 \f
3235 /* ARG is a tree that is known to contain just arithmetic operations and
3236 comparisons. Evaluate the operations in the tree substituting NEW0 for
3237 any occurrence of OLD0 as an operand of a comparison and likewise for
3238 NEW1 and OLD1. */
3240 static tree
3243 {
3248 /* We can handle some of the tcc_expression cases here. */
3256 {
3271 {
3290 }
3291 /* Fall through - ??? */
3294 {
3298 /* We need to check both for exact equality and tree equality. The
3299 former will be true if the operand has a side-effect. In that
3300 case, we know the operand occurred exactly once. */
3313 }
3317 }
3318 }
3319 \f
3320 /* Return a tree for the case when the result of an expression is RESULT
3321 converted to TYPE and OMITTED was previously an operand of the expression
3322 but is now not needed (e.g., we folded OMITTED * 0).
3324 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3325 the conversion of RESULT to TYPE. */
3327 tree
3329 {
3332 /* If the resulting operand is an empty statement, just return the omitted
3333 statement casted to void. */
3343 }
3345 /* Return a tree for the case when the result of an expression is RESULT
3346 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3347 of the expression but are now not needed.
3349 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3350 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3351 evaluated before OMITTED2. Otherwise, if neither has side effects,
3352 just do the conversion of RESULT to TYPE. */
3354 tree
3357 {
3366 }
3368 \f
3369 /* Return a simplified tree node for the truth-negation of ARG. This
3370 never alters ARG itself. We assume that ARG is an operation that
3371 returns a truth value (0 or 1).
3373 FIXME: one would think we would fold the result, but it causes
3374 problems with the dominator optimizer. */
3376 static tree
3378 {
3383 /* If this is a comparison, we can simply invert it, except for
3384 floating-point non-equality comparisons, in which case we just
3385 enclose a TRUTH_NOT_EXPR around what we have. */
3388 {
3391 && flag_trapping_math
3402 }
3405 {
3424 /* Here we can invert either operand. We invert the first operand
3425 unless the second operand is a TRUTH_NOT_EXPR in which case our
3426 result is the XOR of the first operand with the inside of the
3427 negation of the second operand. */
3432 else
3455 {
3462 /* A COND_EXPR may have a throw as one operand, which
3463 then has void type. Just leave void operands
3464 as they are. */
3470 }
3482 CASE_CONVERT:
3486 /* ... fall through ... */
3508 }
3509 }
3511 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3512 assume that ARG is an operation that returns a truth value (0 or 1
3513 for scalars, 0 or -1 for vectors). Return the folded expression if
3514 folding is successful. Otherwise, return NULL_TREE. */
3516 static tree
3518 {
3521 ? BIT_NOT_EXPR
3524 }
3526 /* Return a simplified tree node for the truth-negation of ARG. This
3527 never alters ARG itself. We assume that ARG is an operation that
3528 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3530 tree
3532 {
3538 ? BIT_NOT_EXPR
3541 }
3543 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3544 operands are another bit-wise operation with a common input. If so,
3545 distribute the bit operations to save an operation and possibly two if
3546 constants are involved. For example, convert
3547 (A | B) & (A | C) into A | (B & C)
3548 Further simplification will occur if B and C are constants.
3550 If this optimization cannot be done, 0 will be returned. */
3552 static tree
3555 {
3556 tree common;
3566 {
3570 }
3572 {
3576 }
3578 {
3582 }
3584 {
3588 }
3589 else
3597 }
3599 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3600 with code CODE. This optimization is unsafe. */
3601 static tree
3604 {
3608 /* (A / C) +- (B / C) -> (A +- B) / C. */
3618 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3623 {
3635 }
3638 }
3639 \f
3640 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3641 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3643 static tree
3646 {
3650 {
3657 }
3671 }
3673 /* Optimize a bit-field compare.
3675 There are two cases: First is a compare against a constant and the
3676 second is a comparison of two items where the fields are at the same
3677 bit position relative to the start of a chunk (byte, halfword, word)
3678 large enough to contain it. In these cases we can avoid the shift
3679 implicit in bitfield extractions.
3681 For constants, we emit a compare of the shifted constant with the
3682 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3683 compared. For two fields at the same position, we do the ANDs with the
3684 similar mask and compare the result of the ANDs.
3686 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3687 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3688 are the left and right operands of the comparison, respectively.
3690 If the optimization described above can be done, we return the resulting
3691 tree. Otherwise we return zero. */
3693 static tree
3696 {
3699 tree unsigned_type;
3705 tree mask;
3706 tree offset;
3708 /* Get all the information about the extractions being done. If the bit size
3709 if the same as the size of the underlying object, we aren't doing an
3710 extraction at all and so can do nothing. We also don't want to
3711 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3712 then will no longer be able to replace it. */
3720 {
3721 /* If this is not a constant, we can only do something if bit positions,
3722 sizes, and signedness are the same. */
3730 }
3732 /* See if we can find a mode to refer to this field. We should be able to,
3733 but fail if we can't. */
3742 /* Set signed and unsigned types of the precision of this mode for the
3743 shifts below. */
3746 /* Compute the bit position and size for the new reference and our offset
3747 within it. If the new reference is the same size as the original, we
3748 won't optimize anything, so return zero. */
3758 /* Make the mask to be used against the extracted field. */
3765 /* If not comparing with constant, just rework the comparison
3766 and return. */
3770 unsigned_type,
3773 mask),
3776 unsigned_type,
3779 mask));
3781 /* Otherwise, we are handling the constant case. See if the constant is too
3782 big for the field. Warn and return a tree of for 0 (false) if so. We do
3783 this not only for its own sake, but to avoid having to test for this
3784 error case below. If we didn't, we might generate wrong code.
3786 For unsigned fields, the constant shifted right by the field length should
3787 be all zero. For signed fields, the high-order bits should agree with
3788 the sign bit. */
3791 {
3793 {
3797 }
3798 }
3799 else
3800 {
3803 {
3807 }
3808 }
3810 /* Single-bit compares should always be against zero. */
3812 {
3815 }
3817 /* Make a new bitfield reference, shift the constant over the
3818 appropriate number of bits and mask it with the computed mask
3819 (in case this was a signed field). If we changed it, make a new one. */
3826 mask);
3831 }
3832 \f
3833 /* Subroutine for fold_truth_andor_1: decode a field reference.
3835 If EXP is a comparison reference, we return the innermost reference.
3837 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3838 set to the starting bit number.
3840 If the innermost field can be completely contained in a mode-sized
3841 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3843 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3844 otherwise it is not changed.
3846 *PUNSIGNEDP is set to the signedness of the field.
3848 *PMASK is set to the mask used. This is either contained in a
3849 BIT_AND_EXPR or derived from the width of the field.
3851 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3853 Return 0 if this is not a component reference or is one that we can't
3854 do anything with. */
3856 static tree
3861 {
3865 tree unsigned_type;
3868 /* All the optimizations using this function assume integer fields.
3869 There are problems with FP fields since the type_for_size call
3870 below can fail for, e.g., XFmode. */
3874 /* We are interested in the bare arrangement of bits, so strip everything
3875 that doesn't affect the machine mode. However, record the type of the
3876 outermost expression if it may matter below. */
3883 {
3889 }
3898 /* If the number of bits in the reference is the same as the bitsize of
3899 the outer type, then the outer type gives the signedness. Otherwise
3900 (in case of a small bitfield) the signedness is unchanged. */
3904 /* Compute the mask to access the bitfield. */
3913 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3921 }
3923 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3924 bit positions and MASK is SIGNED. */
3926 static int
3928 {
3932 /* If this function returns true when the type of the mask is
3933 UNSIGNED, then there will be errors. In particular see
3934 gcc.c-torture/execute/990326-1.c. There does not appear to be
3935 any documentation paper trail as to why this is so. But the pre
3936 wide-int worked with that restriction and it has been preserved
3937 here. */
3942 }
3944 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3945 represents the sign bit of EXP's type. If EXP represents a sign
3946 or zero extension, also test VAL against the unextended type.
3947 The return value is the (sub)expression whose sign bit is VAL,
3948 or NULL_TREE otherwise. */
3950 tree
3952 {
3954 tree t;
3956 /* Tree EXP must have an integral type. */
3961 /* Tree VAL must be an integer constant. */
3970 /* Handle extension from a narrower type. */
3976 }
3978 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
3979 to be evaluated unconditionally. */
3981 static int
3983 {
3984 /* Strip any conversions that don't change the machine mode. */
3993 /* Don't regard global variables as simple. They may be
3994 allocated in ways unknown to the compiler (shared memory,
3995 #pragma weak, etc). */
3998 /* Weakrefs are not safe to be read, since they can be NULL.
3999 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4000 have DECL_WEAK flag set. */
4002 /* Loading a static variable is unduly expensive, but global
4003 registers aren't expensive. */
4005 }
4007 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4008 to be evaluated unconditionally.
4009 I addition to simple_operand_p, we assume that comparisons, conversions,
4010 and logic-not operations are simple, if their operands are simple, too. */
4012 static bool
4014 {
4034 }
4036 \f
4037 /* The following functions are subroutines to fold_range_test and allow it to
4038 try to change a logical combination of comparisons into a range test.
4040 For example, both
4041 X == 2 || X == 3 || X == 4 || X == 5
4042 and
4043 X >= 2 && X <= 5
4044 are converted to
4045 (unsigned) (X - 2) <= 3
4047 We describe each set of comparisons as being either inside or outside
4048 a range, using a variable named like IN_P, and then describe the
4049 range with a lower and upper bound. If one of the bounds is omitted,
4050 it represents either the highest or lowest value of the type.
4052 In the comments below, we represent a range by two numbers in brackets
4053 preceded by a "+" to designate being inside that range, or a "-" to
4054 designate being outside that range, so the condition can be inverted by
4055 flipping the prefix. An omitted bound is represented by a "-". For
4056 example, "- [-, 10]" means being outside the range starting at the lowest
4057 possible value and ending at 10, in other words, being greater than 10.
4058 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4059 always false.
4061 We set up things so that the missing bounds are handled in a consistent
4062 manner so neither a missing bound nor "true" and "false" need to be
4063 handled using a special case. */
4065 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4066 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4067 and UPPER1_P are nonzero if the respective argument is an upper bound
4068 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4069 must be specified for a comparison. ARG1 will be converted to ARG0's
4070 type if both are specified. */
4072 static tree
4075 {
4076 tree tem;
4080 /* If neither arg represents infinity, do the normal operation.
4081 Else, if not a comparison, return infinity. Else handle the special
4082 comparison rules. Note that most of the cases below won't occur, but
4083 are handled for consistency. */
4086 {
4091 }
4096 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4097 for neither. In real maths, we cannot assume open ended ranges are
4098 the same. But, this is computer arithmetic, where numbers are finite.
4099 We can therefore make the transformation of any unbounded range with
4100 the value Z, Z being greater than any representable number. This permits
4101 us to treat unbounded ranges as equal. */
4105 {
4126 }
4129 }
4130 \f
4131 /* Helper routine for make_range. Perform one step for it, return
4132 new expression if the loop should continue or NULL_TREE if it should
4133 stop. */
4135 tree
4139 {
4145 {
4147 /* We can only do something if the range is testing for zero. */
4156 /* We can only do something if the range is testing for zero
4157 and if the second operand is an integer constant. Note that
4158 saying something is "in" the range we make is done by
4159 complementing IN_P since it will set in the initial case of
4160 being not equal to zero; "out" is leaving it alone. */
4167 {
4188 }
4190 /* If this is an unsigned comparison, we also know that EXP is
4191 greater than or equal to zero. We base the range tests we make
4192 on that fact, so we record it here so we can parse existing
4193 range tests. We test arg0_type since often the return type
4194 of, e.g. EQ_EXPR, is boolean. */
4196 {
4200 NULL_TREE))
4205 /* If the high bound is missing, but we have a nonzero low
4206 bound, reverse the range so it goes from zero to the low bound
4207 minus 1. */
4209 {
4214 }
4215 }
4223 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4224 low and high are non-NULL, then normalize will DTRT. */
4227 {
4232 }
4234 /* (-x) IN [a,b] -> x in [-b, -a] */
4246 /* ~ X -> -X - 1 */
4255 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4256 move a constant to the other side. */
4261 /* If EXP is signed, any overflow in the computation is undefined,
4262 so we don't worry about it so long as our computations on
4263 the bounds don't overflow. For unsigned, overflow is defined
4264 and this is exactly the right thing. */
4276 normalize:
4277 /* Check for an unsigned range which has wrapped around the maximum
4278 value thus making n_high < n_low, and normalize it. */
4280 {
4286 /* If the range is of the form +/- [ x+1, x ], we won't
4287 be able to normalize it. But then, it represents the
4288 whole range or the empty set, so make it
4289 +/- [ -, - ]. */
4293 else
4295 }
4296 else
4304 CASE_CONVERT:
4322 /* If we're converting arg0 from an unsigned type, to exp,
4323 a signed type, we will be doing the comparison as unsigned.
4324 The tests above have already verified that LOW and HIGH
4325 are both positive.
4327 So we have to ensure that we will handle large unsigned
4328 values the same way that the current signed bounds treat
4329 negative values. */
4332 {
4333 tree high_positive;
4334 tree equiv_type;
4335 /* For fixed-point modes, we need to pass the saturating flag
4336 as the 2nd parameter. */
4338 equiv_type
4341 else
4342 equiv_type
4345 /* A range without an upper bound is, naturally, unbounded.
4346 Since convert would have cropped a very large value, use
4347 the max value for the destination type. */
4348 high_positive
4355 high_positive),
4358 /* If the low bound is specified, "and" the range with the
4359 range for which the original unsigned value will be
4360 positive. */
4362 {
4365 integer_zero_node),
4366 high_positive))
4370 }
4371 else
4372 {
4373 /* Otherwise, "or" the range with the range of the input
4374 that will be interpreted as negative. */
4377 integer_zero_node),
4378 high_positive))
4382 }
4383 }
4392 }
4393 }
4395 /* Given EXP, a logical expression, set the range it is testing into
4396 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4397 actually being tested. *PLOW and *PHIGH will be made of the same
4398 type as the returned expression. If EXP is not a comparison, we
4399 will most likely not be returning a useful value and range. Set
4400 *STRICT_OVERFLOW_P to true if the return value is only valid
4401 because signed overflow is undefined; otherwise, do not change
4402 *STRICT_OVERFLOW_P. */
4404 tree
4407 {
4415 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4416 and see if we can refine the range. Some of the cases below may not
4417 happen, but it doesn't seem worth worrying about this. We "continue"
4418 the outer loop when we've changed something; otherwise we "break"
4419 the switch, which will "break" the while. */
4425 {
4431 {
4439 }
4448 }
4450 /* If EXP is a constant, we can evaluate whether this is true or false. */
4452 {
4459 }
4463 }
4464 \f
4465 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4466 type, TYPE, return an expression to test if EXP is in (or out of, depending
4467 on IN_P) the range. Return 0 if the test couldn't be created. */
4469 tree
4472 {
4475 #ifdef HAVE_canonicalize_funcptr_for_compare
4476 /* Disable this optimization for function pointer expressions
4477 on targets that require function pointer canonicalization. */
4482 #endif
4485 {
4491 }
4509 {
4511 {
4515 }
4517 }
4519 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4521 {
4525 {
4527 {
4530 etype
4532 else
4535 }
4538 }
4539 }
4541 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4542 This requires wrap-around arithmetics for the type of the expression.
4543 First make sure that arithmetics in this type is valid, then make sure
4544 that it wraps around. */
4550 {
4553 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4554 for the type in question, as we rely on this here. */
4564 else
4566 }
4576 {
4578 {
4583 }
4585 }
4593 }
4594 \f
4595 /* Return the predecessor of VAL in its type, handling the infinite case. */
4597 static tree
4599 {
4605 else
4608 }
4610 /* Return the successor of VAL in its type, handling the infinite case. */
4612 static tree
4614 {
4620 else
4623 }
4625 /* Given two ranges, see if we can merge them into one. Return 1 if we
4626 can, 0 if we can't. Set the output range into the specified parameters. */
4628 bool
4631 {
4635 tree tem;
4645 /* Make range 0 be the range that starts first, or ends last if they
4646 start at the same value. Swap them if it isn't. */
4649 || (lowequal
4652 {
4656 }
4658 /* Now flag two cases, whether the ranges are disjoint or whether the
4659 second range is totally subsumed in the first. Note that the tests
4660 below are simplified by the ones above. */
4666 /* We now have four cases, depending on whether we are including or
4667 excluding the two ranges. */
4669 {
4670 /* If they don't overlap, the result is false. If the second range
4671 is a subset it is the result. Otherwise, the range is from the start
4672 of the second to the end of the first. */
4677 else
4679 }
4682 {
4683 /* If they don't overlap, the result is the first range. If they are
4684 equal, the result is false. If the second range is a subset of the
4685 first, and the ranges begin at the same place, we go from just after
4686 the end of the second range to the end of the first. If the second
4687 range is not a subset of the first, or if it is a subset and both
4688 ranges end at the same place, the range starts at the start of the
4689 first range and ends just before the second range.
4690 Otherwise, we can't describe this as a single range. */
4696 {
4701 {
4702 /* We are in the weird situation where high0 > high1 but
4703 high1 has no successor. Punt. */
4705 }
4706 }
4708 {
4713 {
4714 /* low0 < low1 but low1 has no predecessor. Punt. */
4716 }
4717 }
4718 else
4720 }
4723 {
4724 /* If they don't overlap, the result is the second range. If the second
4725 is a subset of the first, the result is false. Otherwise,
4726 the range starts just after the first range and ends at the
4727 end of the second. */
4732 else
4733 {
4738 {
4739 /* high1 > high0 but high0 has no successor. Punt. */
4741 }
4742 }
4743 }
4745 else
4746 {
4747 /* The case where we are excluding both ranges. Here the complex case
4748 is if they don't overlap. In that case, the only time we have a
4749 range is if they are adjacent. If the second is a subset of the
4750 first, the result is the first. Otherwise, the range to exclude
4751 starts at the beginning of the first range and ends at the end of the
4752 second. */
4754 {
4759 else
4760 {
4761 /* Canonicalize - [min, x] into - [-, x]. */
4764 {
4769 /* FALLTHROUGH */
4782 }
4784 /* Canonicalize - [x, max] into - [x, -]. */
4787 {
4792 /* FALLTHROUGH */
4808 }
4810 /* The ranges might be also adjacent between the maximum and
4811 minimum values of the given type. For
4812 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4813 return + [x + 1, y - 1]. */
4815 {
4822 }
4823 else
4825 }
4826 }
4829 else
4831 }
4835 }
4836 \f
4838 /* Subroutine of fold, looking inside expressions of the form
4839 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4840 of the COND_EXPR. This function is being used also to optimize
4841 A op B ? C : A, by reversing the comparison first.
4843 Return a folded expression whose code is not a COND_EXPR
4844 anymore, or NULL_TREE if no folding opportunity is found. */
4846 static tree
4849 {
4854 tree tem;
4859 /* If we have A op 0 ? A : -A, consider applying the following
4860 transformations:
4862 A == 0? A : -A same as -A
4863 A != 0? A : -A same as A
4864 A >= 0? A : -A same as abs (A)
4865 A > 0? A : -A same as abs (A)
4866 A <= 0? A : -A same as -abs (A)
4867 A < 0? A : -A same as -abs (A)
4869 None of these transformations work for modes with signed
4870 zeros. If A is +/-0, the first two transformations will
4871 change the sign of the result (from +0 to -0, or vice
4872 versa). The last four will fix the sign of the result,
4873 even though the original expressions could be positive or
4874 negative, depending on the sign of A.
4876 Note that all these transformations are correct if A is
4877 NaN, since the two alternatives (A and -A) are also NaNs. */
4884 /* In the case that A is of the form X-Y, '-A' (arg2) may
4885 have already been folded to Y-X, check for that. */
4893 {
4907 /* Fall through. */
4929 }
4931 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4932 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4933 both transformations are correct when A is NaN: A != 0
4934 is then true, and A == 0 is false. */
4938 {
4943 }
4945 /* Try some transformations of A op B ? A : B.
4947 A == B? A : B same as B
4948 A != B? A : B same as A
4949 A >= B? A : B same as max (A, B)
4950 A > B? A : B same as max (B, A)
4951 A <= B? A : B same as min (A, B)
4952 A < B? A : B same as min (B, A)
4954 As above, these transformations don't work in the presence
4955 of signed zeros. For example, if A and B are zeros of
4956 opposite sign, the first two transformations will change
4957 the sign of the result. In the last four, the original
4958 expressions give different results for (A=+0, B=-0) and
4959 (A=-0, B=+0), but the transformed expressions do not.
4961 The first two transformations are correct if either A or B
4962 is a NaN. In the first transformation, the condition will
4963 be false, and B will indeed be chosen. In the case of the
4964 second transformation, the condition A != B will be true,
4965 and A will be chosen.
4967 The conversions to max() and min() are not correct if B is
4968 a number and A is not. The conditions in the original
4969 expressions will be false, so all four give B. The min()
4970 and max() versions would give a NaN instead. */
4973 /* Avoid these transformations if the COND_EXPR may be used
4974 as an lvalue in the C++ front-end. PR c++/19199. */
4975 && (in_gimple_form
4981 {
4986 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4988 {
4992 }
4995 {
5004 /* In C++ a ?: expression can be an lvalue, so put the
5005 operand which will be used if they are equal first
5006 so that we can convert this back to the
5007 corresponding COND_EXPR. */
5009 {
5018 }
5025 {
5034 }
5049 }
5050 }
5052 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5053 we might still be able to simplify this. For example,
5054 if C1 is one less or one more than C2, this might have started
5055 out as a MIN or MAX and been transformed by this function.
5056 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5062 {
5066 /* We can replace A with C1 in this case. */
5071 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5072 MIN_EXPR, to preserve the signedness of the comparison. */
5074 OEP_ONLY_CONST)
5078 OEP_ONLY_CONST))
5079 {
5082 arg2));
5085 }
5089 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5090 as above. */
5092 OEP_ONLY_CONST)
5096 OEP_ONLY_CONST))
5097 {
5100 arg2));
5103 }
5107 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5108 MAX_EXPR, to preserve the signedness of the comparison. */
5110 OEP_ONLY_CONST)
5114 OEP_ONLY_CONST))
5115 {
5118 arg2));
5120 }
5124 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5126 OEP_ONLY_CONST)
5130 OEP_ONLY_CONST))
5131 {
5134 arg2));
5136 }
5142 }
5145 }
5148 \f
5149 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5150 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5151 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5152 false) >= 2)
5153 #endif
5155 /* EXP is some logical combination of boolean tests. See if we can
5156 merge it into some range test. Return the new tree if so. */
5158 static tree
5161 {
5177 /* If this is an OR operation, invert both sides; we will invert
5178 again at the end. */
5182 /* If both expressions are the same, if we can merge the ranges, and we
5183 can build the range test, return it or it inverted. If one of the
5184 ranges is always true or always false, consider it to be the same
5185 expression as the other. */
5193 {
5197 }
5199 /* On machines where the branch cost is expensive, if this is a
5200 short-circuited branch and the underlying object on both sides
5201 is the same, make a non-short-circuit operation. */
5207 {
5208 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5209 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5210 which cases we can't do this. */
5218 {
5227 {
5230 WARN_STRICT_OVERFLOW_COMPARISON);
5234 }
5235 }
5236 }
5239 }
5240 \f
5241 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5242 bit value. Arrange things so the extra bits will be set to zero if and
5243 only if C is signed-extended to its full width. If MASK is nonzero,
5244 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5246 static tree
5248 {
5251 tree temp;
5256 /* We work by getting just the sign bit into the low-order bit, then
5257 into the high-order bit, then sign-extend. We then XOR that value
5258 with C. */
5261 /* We must use a signed type in order to get an arithmetic right shift.
5262 However, we must also avoid introducing accidental overflows, so that
5263 a subsequent call to integer_zerop will work. Hence we must
5264 do the type conversion here. At this point, the constant is either
5265 zero or one, and the conversion to a signed type can never overflow.
5266 We could get an overflow if this conversion is done anywhere else. */
5275 /* If necessary, convert the type back to match the type of C. */
5280 }
5281 \f
5282 /* For an expression that has the form
5283 (A && B) || ~B
5284 or
5285 (A || B) && ~B,
5286 we can drop one of the inner expressions and simplify to
5287 A || ~B
5288 or
5289 A && ~B
5290 LOC is the location of the resulting expression. OP is the inner
5291 logical operation; the left-hand side in the examples above, while CMPOP
5292 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5293 removing a condition that guards another, as in
5294 (A != NULL && A->...) || A == NULL
5295 which we must not transform. If RHS_ONLY is true, only eliminate the
5296 right-most operand of the inner logical operation. */
5298 static tree
5301 {
5319 {
5322 {
5325 }
5326 }
5328 {
5331 {
5334 }
5335 }
5350 }
5352 /* Find ways of folding logical expressions of LHS and RHS:
5353 Try to merge two comparisons to the same innermost item.
5354 Look for range tests like "ch >= '0' && ch <= '9'".
5355 Look for combinations of simple terms on machines with expensive branches
5356 and evaluate the RHS unconditionally.
5358 For example, if we have p->a == 2 && p->b == 4 and we can make an
5359 object large enough to span both A and B, we can do this with a comparison
5360 against the object ANDed with the a mask.
5362 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5363 operations to do this with one comparison.
5365 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5366 function and the one above.
5368 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5369 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5371 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5372 two operands.
5374 We return the simplified tree or 0 if no optimization is possible. */
5376 static tree
5379 {
5380 /* If this is the "or" of two comparisons, we can do something if
5381 the comparisons are NE_EXPR. If this is the "and", we can do something
5382 if the comparisons are EQ_EXPR. I.e.,
5383 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5385 WANTED_CODE is this operation code. For single bit fields, we can
5386 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5387 comparison for one-bit fields. */
5407 /* Start by getting the comparison codes. Fail if anything is volatile.
5408 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5409 it were surrounded with a NE_EXPR. */
5418 {
5422 }
5425 {
5429 }
5440 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5443 {
5446 {
5451 }
5454 {
5460 }
5461 }
5466 /* If the RHS can be evaluated unconditionally and its operands are
5467 simple, it wins to evaluate the RHS unconditionally on machines
5468 with expensive branches. In this case, this isn't a comparison
5469 that can be merged. */
5476 {
5477 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5488 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5498 }
5500 /* See if the comparisons can be merged. Then get all the parameters for
5501 each side. */
5525 /* It must be true that the inner operation on the lhs of each
5526 comparison must be the same if we are to be able to do anything.
5527 Then see if we have constants. If not, the same must be true for
5528 the rhs's. */
5539 else
5542 /* If either comparison code is not correct for our logical operation,
5543 fail. However, we can convert a one-bit comparison against zero into
5544 the opposite comparison against that bit being set in the field. */
5548 {
5550 {
5551 /* Make the left operand unsigned, since we are only interested
5552 in the value of one bit. Otherwise we are doing the wrong
5553 thing below. */
5556 }
5557 else
5559 }
5561 /* This is analogous to the code for l_const above. */
5563 {
5565 {
5568 }
5569 else
5571 }
5573 /* See if we can find a mode that contains both fields being compared on
5574 the left. If we can't, fail. Otherwise, update all constants and masks
5575 to be relative to a field of that size. */
5580 volatilep);
5590 {
5593 }
5601 {
5608 {
5612 }
5613 }
5615 {
5622 {
5626 }
5627 }
5629 /* If the right sides are not constant, do the same for it. Also,
5630 disallow this optimization if a size or signedness mismatch occurs
5631 between the left and right sides. */
5633 {
5636 /* Make sure the two fields on the right
5637 correspond to the left without being swapped. */
5645 volatilep);
5655 {
5658 }
5667 /* Make a mask that corresponds to both fields being compared.
5668 Do this for both items being compared. If the operands are the
5669 same size and the bits being compared are in the same position
5670 then we can do this by masking both and comparing the masked
5671 results. */
5675 {
5687 }
5689 /* There is still another way we can do something: If both pairs of
5690 fields being compared are adjacent, we may be able to make a wider
5691 field containing them both.
5693 Note that we still must mask the lhs/rhs expressions. Furthermore,
5694 the mask must be shifted to account for the shift done by
5695 make_bit_field_ref. */
5700 {
5701 tree type;
5715 /* Convert to the smaller type before masking out unwanted bits. */
5718 {
5720 {
5724 }
5726 {
5730 }
5731 }
5740 }
5743 }
5745 /* Handle the case of comparisons with constants. If there is something in
5746 common between the masks, those bits of the constants must be the same.
5747 If not, the condition is always false. Test for this to avoid generating
5748 incorrect code below. */
5753 {
5755 {
5758 }
5759 else
5760 {
5763 }
5764 }
5766 /* Construct the expression we will return. First get the component
5767 reference we will make. Unless the mask is all ones the width of
5768 that field, perform the mask operation. Then compare with the
5769 merged constant. */
5779 }
5780 \f
5781 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5782 constant. */
5784 static tree
5787 {
5790 tree comp_const;
5791 tree minmax_const;
5793 tree inner;
5804 /* If something does not permit us to optimize, return the original tree. */
5812 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5813 and GT_EXPR, doing the rest with recursive calls using logical
5814 simplifications. */
5816 {
5818 {
5819 tree tem
5826 }
5829 return
5831 optimize_minmax_comparison
5833 optimize_minmax_comparison
5838 /* MAX (X, 0) == 0 -> X <= 0 */
5842 /* MAX (X, 0) == 5 -> X == 5 */
5846 /* MAX (X, 0) == -1 -> false */
5850 /* MIN (X, 0) == 0 -> X >= 0 */
5854 /* MIN (X, 0) == 5 -> false */
5857 else
5858 /* MIN (X, 0) == -1 -> X == -1 */
5863 /* MAX (X, 0) > 0 -> X > 0
5864 MAX (X, 0) > 5 -> X > 5 */
5868 /* MAX (X, 0) > -1 -> true */
5872 /* MIN (X, 0) > 0 -> false
5873 MIN (X, 0) > 5 -> false */
5876 else
5877 /* MIN (X, 0) > -1 -> X > -1 */
5882 }
5883 }
5884 \f
5885 /* T is an integer expression that is being multiplied, divided, or taken a
5886 modulus (CODE says which and what kind of divide or modulus) by a
5887 constant C. See if we can eliminate that operation by folding it with
5888 other operations already in T. WIDE_TYPE, if non-null, is a type that
5889 should be used for the computation if wider than our type.
5891 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5892 (X * 2) + (Y * 4). We must, however, be assured that either the original
5893 expression would not overflow or that overflow is undefined for the type
5894 in the language in question.
5896 If we return a non-null expression, it is an equivalent form of the
5897 original computation, but need not be in the original type.
5899 We set *STRICT_OVERFLOW_P to true if the return values depends on
5900 signed overflow being undefined. Otherwise we do not change
5901 *STRICT_OVERFLOW_P. */
5903 static tree
5906 {
5907 /* To avoid exponential search depth, refuse to allow recursion past
5908 three levels. Beyond that (1) it's highly unlikely that we'll find
5909 something interesting and (2) we've probably processed it before
5910 when we built the inner expression. */
5913 tree ret;
5918 depth++;
5920 depth--;
5923 }
5925 static tree
5928 {
5939 /* Don't deal with constants of zero here; they confuse the code below. */
5949 /* Note that we need not handle conditional operations here since fold
5950 already handles those cases. So just do arithmetic here. */
5952 {
5954 /* For a constant, we can always simplify if we are a multiply
5955 or (for divide and modulus) if it is a multiple of our constant. */
5963 /* If op0 is an expression ... */
5969 /* ... and has wrapping overflow, and its type is smaller
5970 than ctype, then we cannot pass through as widening. */
5975 /* ... or this is a truncation (t is narrower than op0),
5976 then we cannot pass through this narrowing. */
5979 /* ... or signedness changes for division or modulus,
5980 then we cannot pass through this conversion. */
5984 /* ... or has undefined overflow while the converted to
5985 type has not, we cannot do the operation in the inner type
5986 as that would introduce undefined overflow. */
5992 /* Pass the constant down and see if we can make a simplification. If
5993 we can, replace this expression with the inner simplification for
5994 possible later conversion to our or some other type. */
5999 code == MULT_EXPR
6001 strict_overflow_p))))
6006 /* If widening the type changes it from signed to unsigned, then we
6007 must avoid building ABS_EXPR itself as unsigned. */
6009 {
6013 {
6016 }
6018 }
6019 /* If the constant is negative, we cannot simplify this. */
6022 /* FALLTHROUGH */
6024 /* For division and modulus, type can't be unsigned, as e.g.
6025 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6026 For signed types, even with wrapping overflow, this is fine. */
6035 /* If widening the type changes the signedness, then we can't perform
6036 this optimization as that changes the result. */
6040 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6046 {
6053 }
6057 /* If the second operand is constant, this is a multiplication
6058 or floor division, by a power of two, so we can treat it that
6059 way unless the multiplier or divisor overflows. Signed
6060 left-shift overflow is implementation-defined rather than
6061 undefined in C90, so do not convert signed left shift into
6062 multiplication. */
6065 /* const_binop may not detect overflow correctly,
6066 so check for it explicitly here. */
6070 size_one_node,
6071 op1)))
6075 ctype,
6077 t1),
6082 /* See if we can eliminate the operation on both sides. If we can, we
6083 can return a new PLUS or MINUS. If we can't, the only remaining
6084 cases where we can do anything are if the second operand is a
6085 constant. */
6091 /* If not multiplication, we can only do this if both operands
6092 are divisible by c. */
6095 {
6100 }
6102 /* If this was a subtraction, negate OP1 and set it to be an addition.
6103 This simplifies the logic below. */
6105 {
6107 /* If OP1 was not easily negatable, the constant may be OP0. */
6109 {
6116 }
6117 }
6122 /* If either OP1 or C are negative, this optimization is not safe for
6123 some of the division and remainder types while for others we need
6124 to change the code. */
6126 {
6134 }
6136 /* If it's a multiply or a division/modulus operation of a multiple
6137 of our constant, do the operation and verify it doesn't overflow. */
6140 {
6143 /* We allow the constant to overflow with wrapping semantics. */
6147 }
6148 else
6151 /* If we have an unsigned type, we cannot widen the operation since it
6152 will change the result if the original computation overflowed. */
6156 /* If we were able to eliminate our operation from the first side,
6157 apply our operation to the second side and reform the PLUS. */
6161 /* The last case is if we are a multiply. In that case, we can
6162 apply the distributive law to commute the multiply and addition
6163 if the multiplication of the constants doesn't overflow
6164 and overflow is defined. With undefined overflow
6165 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6171 op1);
6176 /* We have a special case here if we are doing something like
6177 (C * 8) % 4 since we know that's zero. */
6180 /* If the multiplication can overflow we cannot optimize this. */
6184 {
6187 }
6189 /* ... fall through ... */
6193 /* If we can extract our operation from the LHS, do so and return a
6194 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6195 do something only if the second operand is a constant. */
6209 /* If these are the same operation types, we can associate them
6210 assuming no overflow. */
6212 {
6224 }
6226 /* If these operations "cancel" each other, we have the main
6227 optimizations of this pass, which occur when either constant is a
6228 multiple of the other, in which case we replace this with either an
6229 operation or CODE or TCODE.
6231 If we have an unsigned type, we cannot do this since it will change
6232 the result if the original computation overflowed. */
6239 {
6241 {
6248 }
6250 {
6257 }
6258 }
6263 }
6266 }
6267 \f
6268 /* Return a node which has the indicated constant VALUE (either 0 or
6269 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6270 and is of the indicated TYPE. */
6272 tree
6274 {
6283 else
6285 }
6288 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6289 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6290 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6291 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6292 COND is the first argument to CODE; otherwise (as in the example
6293 given here), it is the second argument. TYPE is the type of the
6294 original expression. Return NULL_TREE if no simplification is
6295 possible. */
6297 static tree
6302 {
6312 {
6316 /* If this operand throws an expression, then it does not make
6317 sense to try to perform a logical or arithmetic operation
6318 involving it. */
6323 }
6324 else
6325 {
6330 }
6335 /* This transformation is only worthwhile if we don't have to wrap ARG
6336 in a SAVE_EXPR and the operation can be simplified without recursing
6337 on at least one of the branches once its pushed inside the COND_EXPR. */
6346 {
6350 else
6352 }
6354 {
6358 else
6360 }
6362 /* Check that we have simplified at least one of the branches. */
6367 }
6369 \f
6370 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6372 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6373 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6374 ADDEND is the same as X.
6376 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6377 and finite. The problematic cases are when X is zero, and its mode
6378 has signed zeros. In the case of rounding towards -infinity,
6379 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6380 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6382 bool
6384 {
6388 /* Don't allow the fold with -fsignaling-nans. */
6392 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6396 /* In a vector or complex, we would need to check the sign of all zeros. */
6400 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6404 /* The mode has signed zeros, and we have to honor their sign.
6405 In this situation, there is only one case we can return true for.
6406 X - 0 is the same as X unless rounding towards -infinity is
6407 supported. */
6409 }
6411 /* Subroutine of fold() that checks comparisons of built-in math
6412 functions against real constants.
6414 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6415 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6416 is the type of the result and ARG0 and ARG1 are the operands of the
6417 comparison. ARG1 must be a TREE_REAL_CST.
6419 The function returns the constant folded tree if a simplification
6420 can be made, and NULL_TREE otherwise. */
6422 static tree
6426 {
6427 REAL_VALUE_TYPE c;
6430 {
6436 {
6437 /* sqrt(x) < y is always false, if y is negative. */
6441 /* sqrt(x) > y is always true, if y is negative and we
6442 don't care about NaNs, i.e. negative values of x. */
6446 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6449 }
6451 {
6452 REAL_VALUE_TYPE c2;
6458 {
6459 /* sqrt(x) > y is x == +Inf, when y is very large. */
6464 /* sqrt(x) > y is always false, when y is very large
6465 and we don't care about infinities. */
6467 }
6469 /* sqrt(x) > c is the same as x > c*c. */
6472 }
6474 {
6475 REAL_VALUE_TYPE c2;
6481 {
6482 /* sqrt(x) < y is always true, when y is a very large
6483 value and we don't care about NaNs or Infinities. */
6487 /* sqrt(x) < y is x != +Inf when y is very large and we
6488 don't care about NaNs. */
6493 /* sqrt(x) < y is x >= 0 when y is very large and we
6494 don't care about Infinities. */
6499 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6504 dconst0)),
6507 c2)));
6508 }
6510 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6515 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6520 dconst0)),
6523 c2)));
6524 }
6525 }
6528 }
6530 /* Subroutine of fold() that optimizes comparisons against Infinities,
6531 either +Inf or -Inf.
6533 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6534 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6535 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6537 The function returns the constant folded tree if a simplification
6538 can be made, and NULL_TREE otherwise. */
6540 static tree
6543 {
6544 machine_mode mode;
6545 REAL_VALUE_TYPE max;
6546 tree temp;
6551 /* For negative infinity swap the sense of the comparison. */
6557 {
6559 /* x > +Inf is always false, if with ignore sNANs. */
6565 /* x <= +Inf is always true, if we don't case about NaNs. */
6569 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6575 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6581 /* x < +Inf is always equal to x <= DBL_MAX. */
6587 /* x != +Inf is always equal to !(x > DBL_MAX). */
6599 }
6602 }
6604 /* Subroutine of fold() that optimizes comparisons of a division by
6605 a nonzero integer constant against an integer constant, i.e.
6606 X/C1 op C2.
6608 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6609 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6610 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6612 The function returns the constant folded tree if a simplification
6613 can be made, and NULL_TREE otherwise. */
6615 static tree
6618 {
6626 /* We have to do this the hard way to detect unsigned overflow.
6627 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6633 {
6638 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6642 }
6644 {
6648 {
6667 }
6668 }
6669 else
6670 {
6671 /* A negative divisor reverses the relational operators. */
6677 {
6696 }
6697 }
6700 {
6721 {
6724 }
6729 {
6732 }
6737 {
6740 }
6745 {
6748 }
6753 }
6756 }
6759 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6760 equality/inequality test, then return a simplified form of the test
6761 using a sign testing. Otherwise return NULL. TYPE is the desired
6762 result type. */
6764 static tree
6767 tree result_type)
6768 {
6769 /* If this is testing a single bit, we can optimize the test. */
6773 {
6774 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6775 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6779 /* This is only a win if casting to a signed type is cheap,
6780 i.e. when arg00's type is not a partial mode. */
6783 {
6786 result_type,
6789 }
6790 }
6793 }
6795 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6796 equality/inequality test, then return a simplified form of
6797 the test using shifts and logical operations. Otherwise return
6798 NULL. TYPE is the desired result type. */
6800 tree
6803 {
6804 /* If this is testing a single bit, we can optimize the test. */
6808 {
6817 /* First, see if we can fold the single bit test into a sign-bit
6818 test. */
6820 result_type);
6824 /* Otherwise we have (A & C) != 0 where C is a single bit,
6825 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6826 Similarly for (A & C) == 0. */
6828 /* If INNER is a right shift of a constant and it plus BITNUM does
6829 not overflow, adjust BITNUM and INNER. */
6835 {
6838 }
6840 /* If we are going to be able to omit the AND below, we must do our
6841 operations as unsigned. If we must use the AND, we have a choice.
6842 Normally unsigned is faster, but for some machines signed is. */
6843 #ifdef LOAD_EXTEND_OP
6846 #else
6848 #endif
6864 /* Put the AND last so it can combine with more things. */
6867 /* Make sure to return the proper type. */
6871 }
6873 }
6875 /* Check whether we are allowed to reorder operands arg0 and arg1,
6876 such that the evaluation of arg1 occurs before arg0. */
6878 static bool
6880 {
6887 }
6889 /* Test whether it is preferable two swap two operands, ARG0 and
6890 ARG1, for example because ARG0 is an integer constant and ARG1
6891 isn't. If REORDER is true, only recommend swapping if we can
6892 evaluate the operands in reverse order. */
6894 bool
6896 {
6914 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6915 for commutative and comparison operators. Ensuring a canonical
6916 form allows the optimizers to find additional redundancies without
6917 having to explicitly check for both orderings. */
6923 /* Put SSA_NAMEs last. */
6929 /* Put variables last. */
6936 }
6938 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6939 ARG0 is extended to a wider type. */
6941 static tree
6944 {
6946 tree arg1_unw;
6955 #ifdef HAVE_canonicalize_funcptr_for_compare
6956 /* Disable this optimization if we're casting a function pointer
6957 type on targets that require function pointer canonicalization. */
6962 #endif
6969 /* If possible, express the comparison in the shorter mode. */
6989 /* If we are comparing with the integer that does not fit into the range
6990 of the shorter type, the result is known. */
7001 {
7028 }
7031 }
7033 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
7034 ARG0 just the signedness is changed. */
7036 static tree
7039 {
7040 tree arg0_inner;
7050 #ifdef HAVE_canonicalize_funcptr_for_compare
7051 /* Disable this optimization if we're casting a function pointer
7052 type on targets that require function pointer canonicalization. */
7057 #endif
7078 else
7082 }
7085 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7086 means A >= Y && A != MAX, but in this case we know that
7087 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7089 static tree
7091 {
7098 else
7107 {
7110 }
7112 {
7115 }
7116 else
7123 {
7124 /* Convert the pointer types into integer before taking the difference. */
7128 }
7129 else
7136 }
7138 /* Fold a sum or difference of at least one multiplication.
7139 Returns the folded tree or NULL if no simplification could be made. */
7141 static tree
7144 {
7148 /* (A * C) +- (B * C) -> (A+-B) * C.
7149 (A * C) +- A -> A * (C+-1).
7150 We are most concerned about the case where C is a constant,
7151 but other combinations show up during loop reduction. Since
7152 it is not difficult, try all four possibilities. */
7155 {
7158 }
7160 {
7163 }
7164 else
7165 {
7166 /* We cannot generate constant 1 for fract. */
7171 }
7173 {
7176 }
7178 {
7180 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7181 the purpose of this canonicalization. */
7185 {
7188 }
7189 else
7191 }
7192 else
7193 {
7194 /* We cannot generate constant 1 for fract. */
7199 }
7211 /* No identical multiplicands; see if we can find a common
7212 power-of-two factor in non-power-of-two multiplies. This
7213 can help in multi-dimensional array access. */
7216 {
7219 tree maybe_same;
7223 /* Move min of absolute values to int11. */
7225 {
7230 }
7231 else
7235 /* The remainder should not be a constant, otherwise we
7236 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7237 increased the number of multiplications necessary. */
7239 {
7247 }
7248 }
7258 }
7260 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7261 specified by EXPR into the buffer PTR of length LEN bytes.
7262 Return the number of bytes placed in the buffer, or zero
7263 upon failure. */
7265 static int
7267 {
7281 {
7283 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7284 number of bytes. */
7288 {
7295 else
7297 }
7298 else
7303 }
7305 }
7308 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7309 specified by EXPR into the buffer PTR of length LEN bytes.
7310 Return the number of bytes placed in the buffer, or zero
7311 upon failure. */
7313 static int
7315 {
7319 FIXED_VALUE_TYPE value;
7335 }
7338 /* Subroutine of native_encode_expr. Encode the REAL_CST
7339 specified by EXPR into the buffer PTR of length LEN bytes.
7340 Return the number of bytes placed in the buffer, or zero
7341 upon failure. */
7343 static int
7345 {
7351 /* There are always 32 bits in each long, no matter the size of
7352 the hosts long. We handle floating point representations with
7353 up to 192 bits. */
7367 {
7372 {
7379 else
7381 }
7382 else
7388 }
7390 }
7392 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7393 specified by EXPR into the buffer PTR of length LEN bytes.
7394 Return the number of bytes placed in the buffer, or zero
7395 upon failure. */
7397 static int
7399 {
7401 tree part;
7416 }
7419 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7420 specified by EXPR into the buffer PTR of length LEN bytes.
7421 Return the number of bytes placed in the buffer, or zero
7422 upon failure. */
7424 static int
7426 {
7436 {
7438 {
7441 }
7452 }
7454 }
7457 /* Subroutine of native_encode_expr. Encode the STRING_CST
7458 specified by EXPR into the buffer PTR of length LEN bytes.
7459 Return the number of bytes placed in the buffer, or zero
7460 upon failure. */
7462 static int
7464 {
7466 HOST_WIDE_INT total_bytes;
7480 {
7483 {
7486 }
7489 }
7490 else
7493 }
7496 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7497 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7498 buffer PTR of length LEN bytes. If OFF is not -1 then start
7499 the encoding at byte offset OFF and encode at most LEN bytes.
7500 Return the number of bytes placed in the buffer, or zero upon failure. */
7502 int
7504 {
7506 {
7527 }
7528 }
7531 /* Subroutine of native_interpret_expr. Interpret the contents of
7532 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7533 If the buffer cannot be interpreted, return NULL_TREE. */
7535 static tree
7537 {
7547 }
7550 /* Subroutine of native_interpret_expr. Interpret the contents of
7551 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7552 If the buffer cannot be interpreted, return NULL_TREE. */
7554 static tree
7556 {
7558 double_int result;
7559 FIXED_VALUE_TYPE fixed_value;
7569 }
7572 /* Subroutine of native_interpret_expr. Interpret the contents of
7573 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7574 If the buffer cannot be interpreted, return NULL_TREE. */
7576 static tree
7578 {
7583 /* There are always 32 bits in each long, no matter the size of
7584 the hosts long. We handle floating point representations with
7585 up to 192 bits. */
7586 REAL_VALUE_TYPE r;
7597 {
7600 {
7607 else
7609 }
7610 else
7615 }
7619 }
7622 /* Subroutine of native_interpret_expr. Interpret the contents of
7623 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7624 If the buffer cannot be interpreted, return NULL_TREE. */
7626 static tree
7628 {
7643 }
7646 /* Subroutine of native_interpret_expr. Interpret the contents of
7647 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7648 If the buffer cannot be interpreted, return NULL_TREE. */
7650 static tree
7652 {
7665 {
7670 }
7672 }
7675 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7676 the buffer PTR of length LEN as a constant of type TYPE. For
7677 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7678 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7679 return NULL_TREE. */
7681 tree
7683 {
7685 {
7707 }
7708 }
7710 /* Returns true if we can interpret the contents of a native encoding
7711 as TYPE. */
7713 static bool
7715 {
7717 {
7730 }
7731 }
7733 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7734 TYPE at compile-time. If we're unable to perform the conversion
7735 return NULL_TREE. */
7737 static tree
7739 {
7740 /* We support up to 512-bit values (for V8DFmode). */
7744 /* Check that the host and target are sane. */
7753 }
7755 /* Build an expression for the address of T. Folds away INDIRECT_REF
7756 to avoid confusing the gimplify process. */
7758 tree
7760 {
7761 /* The size of the object is not relevant when talking about its address. */
7766 {
7771 }
7781 {
7786 }
7787 else
7791 }
7793 /* Build an expression for the address of T. */
7795 tree
7797 {
7801 }
7803 /* Fold a unary expression of code CODE and type TYPE with operand
7804 OP0. Return the folded expression if folding is successful.
7805 Otherwise, return NULL_TREE. */
7807 tree
7809 {
7810 tree tem;
7811 tree arg0;
7819 {
7822 {
7823 /* Don't use STRIP_NOPS, because signedness of argument type
7824 matters. */
7826 }
7827 else
7828 {
7829 /* Strip any conversions that don't change the mode. This
7830 is safe for every expression, except for a comparison
7831 expression because its signedness is derived from its
7832 operands.
7834 Note that this is done as an internal manipulation within
7835 the constant folder, in order to find the simplest
7836 representation of the arguments so that their form can be
7837 studied. In any cases, the appropriate type conversions
7838 should be put back in the tree that will get out of the
7839 constant folder. */
7841 }
7844 {
7847 {
7851 }
7852 }
7853 }
7860 {
7867 {
7881 /* If this was a conversion, and all we did was to move into
7882 inside the COND_EXPR, bring it back out. But leave it if
7883 it is a conversion from integer to integer and the
7884 result precision is no wider than a word since such a
7885 conversion is cheap and may be optimized away by combine,
7886 while it couldn't if it were outside the COND_EXPR. Then return
7887 so we don't get into an infinite recursion loop taking the
7888 conversion out and then back in. */
7900 && (INTEGRAL_TYPE_P
7913 }
7914 }
7917 {
7923 CASE_CONVERT:
7927 {
7928 /* If we have (type) (a CMP b) and type is an integral type, return
7929 new expression involving the new type. Canonicalize
7930 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7931 non-integral type.
7932 Do not fold the result as that would not simplify further, also
7933 folding again results in recursions. */
7943 }
7945 /* Handle (T *)&A.B.C for A being of type T and B and C
7946 living at offset zero. This occurs frequently in
7947 C++ upcasting and then accessing the base. */
7951 {
7953 tree offset;
7954 machine_mode mode;
7959 /* If the reference was to a (constant) zero offset, we can use
7960 the address of the base if it has the same base type
7961 as the result type and the pointer type is unqualified. */
7968 }
7972 /* Detect assigning a bitfield. */
7974 && DECL_BIT_FIELD
7976 {
7977 /* Don't leave an assignment inside a conversion
7978 unless assigning a bitfield. */
7980 /* First do the assignment, then return converted constant. */
7985 }
7987 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7988 constants (if x has signed type, the sign bit cannot be set
7989 in c). This folds extension into the BIT_AND_EXPR.
7990 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7991 very likely don't have maximal range for their precision and this
7992 transformation effectively doesn't preserve non-maximal ranges. */
7996 {
8007 <= HOST_BITS_PER_WIDE_INT
8009 {
8013 cst &= HOST_WIDE_INT_M1U
8016 #ifdef LOAD_EXTEND_OP
8018 && !flag_syntax_only
8021 {
8025 }
8026 #endif
8027 }
8029 {
8034 }
8035 }
8037 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
8038 when one of the new casts will fold away. Conservatively we assume
8039 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
8046 {
8050 return fold_build_pointer_plus_loc
8052 }
8054 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8055 of the same precision, and X is an integer type not narrower than
8056 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8062 {
8068 }
8070 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8071 type of X and Y (integer types only). */
8076 {
8077 /* Be careful not to introduce new overflows. */
8078 tree mult_type;
8081 else
8085 {
8092 }
8093 }
8111 /* Convert fabs((double)float) into (double)fabsf(float). */
8114 {
8120 targ0));
8121 }
8122 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8126 /* Strip sign ops from argument. */
8128 {
8133 }
8140 {
8146 }
8152 /* Convert ~ (-A) to A - 1. */
8157 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8163 {
8164 /* Perform the negation in ARG0's type and only then convert
8165 to TYPE as to avoid introducing undefined behavior. */
8170 }
8171 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8190 /* Note that the operand of this must be an int
8191 and its values must be 0 or 1.
8192 ("true" is a fixed value perhaps depending on the language,
8193 but we don't handle values other than 1 correctly yet.) */
8203 {
8211 }
8213 {
8218 }
8220 {
8224 {
8233 }
8234 }
8241 {
8249 }
8251 {
8255 }
8257 {
8261 {
8270 }
8271 }
8275 /* Fold *&X to X if X is an lvalue. */
8277 {
8284 }
8290 }
8293 /* If the operation was a conversion do _not_ mark a resulting constant
8294 with TREE_OVERFLOW if the original constant was not. These conversions
8295 have implementation defined behavior and retaining the TREE_OVERFLOW
8296 flag here would confuse later passes such as VRP. */
8297 tree
8300 {
8309 }
8311 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8312 operands OP0 and OP1. LOC is the location of the resulting expression.
8313 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8314 Return the folded expression if folding is successful. Otherwise,
8315 return NULL_TREE. */
8316 static tree
8319 {
8320 tree tem;
8322 /* We only do these simplifications if we are optimizing. */
8326 /* Check for things like (A || B) && (A || C). We can convert this
8327 to A || (B && C). Note that either operator can be any of the four
8328 truth and/or operations and the transformation will still be
8329 valid. Also note that we only care about order for the
8330 ANDIF and ORIF operators. If B contains side effects, this
8331 might change the truth-value of A. */
8338 {
8358 /* This case if tricky because we must either have commutative
8359 operators or else A10 must not have side-effects. */
8365 a01);
8366 }
8368 /* See if we can build a range comparison. */
8374 {
8378 }
8382 {
8386 }
8388 /* Check for the possibility of merging component references. If our
8389 lhs is another similar operation, try to merge its rhs with our
8390 rhs. Then try to merge our lhs and rhs. */
8404 {
8411 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8412 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8413 We don't want to pack more than two leafs to a non-IF AND/OR
8414 expression.
8415 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8416 equal to IF-CODE, then we don't want to add right-hand operand.
8417 If the inner right-hand side of left-hand operand has
8418 side-effects, or isn't simple, then we can't add to it,
8419 as otherwise we might destroy if-sequence. */
8422 /* Needed for sequence points to handle trappings, and
8423 side-effects. */
8425 {
8427 arg1);
8429 tem);
8430 }
8431 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8432 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8435 /* Needed for sequence points to handle trappings, and
8436 side-effects. */
8438 {
8443 }
8444 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8445 into (A OR B).
8446 For sequence point consistancy, we need to check for trapping,
8447 and side-effects. */
8451 }
8454 }
8456 /* Fold a binary expression of code CODE and type TYPE with operands
8457 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8458 Return the folded expression if folding is successful. Otherwise,
8459 return NULL_TREE. */
8461 static tree
8463 {
8470 else
8473 /* MIN (MAX (a, b), b) == b. */
8478 /* MIN (MAX (b, a), b) == b. */
8484 /* MIN (a, MAX (a, b)) == a. */
8490 /* MIN (a, MAX (b, a)) == a. */
8497 }
8499 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8500 by changing CODE to reduce the magnitude of constants involved in
8501 ARG0 of the comparison.
8502 Returns a canonicalized comparison tree if a simplification was
8503 possible, otherwise returns NULL_TREE.
8504 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8505 valid if signed overflow is undefined. */
8507 static tree
8511 {
8517 /* Match A +- CST code arg1 and CST code arg1. We can change the
8518 first form only if overflow is undefined. */
8521 /* In principle pointers also have undefined overflow behavior,
8522 but that causes problems elsewhere. */
8530 /* Identify the constant in arg0 and its sign. */
8533 else
8537 /* Overflowed constants and zero will cause problems. */
8542 /* See if we can reduce the magnitude of the constant in
8543 arg0 by changing the comparison code. */
8545 {
8546 /* CST <= arg1 -> CST-1 < arg1. */
8549 /* -CST < arg1 -> -CST-1 <= arg1. */
8552 /* CST > arg1 -> CST-1 >= arg1. */
8555 /* -CST >= arg1 -> -CST-1 > arg1. */
8558 else
8560 /* arg1 code' CST' might be more canonical. */
8562 }
8563 else
8564 {
8565 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8569 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8573 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8577 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8581 else
8584 }
8586 /* Now build the constant reduced in magnitude. But not if that
8587 would produce one outside of its types range. */
8595 /* We cannot swap the comparison here as that would cause us to
8596 endlessly recurse. */
8605 /* If swapping might yield to a more canonical form, do so. */
8608 else
8610 }
8612 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8613 overflow further. Try to decrease the magnitude of constants involved
8614 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8615 and put sole constants at the second argument position.
8616 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8618 static tree
8621 {
8622 tree t;
8627 /* Try canonicalization by simplifying arg0. */
8632 {
8636 }
8638 /* Try canonicalization by simplifying arg1 using the swapped
8639 comparison. */
8647 }
8649 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8650 space. This is used to avoid issuing overflow warnings for
8651 expressions like &p->x which can not wrap. */
8653 static bool
8655 {
8662 wide_int wi_offset;
8668 else
8684 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8685 array. */
8687 {
8688 HOST_WIDE_INT base_size;
8693 }
8696 }
8698 /* Return the HOST_WIDE_INT least significant bits of T, a sizetype
8699 kind INTEGER_CST. This makes sure to properly sign-extend the
8700 constant. */
8702 static HOST_WIDE_INT
8704 {
8710 }
8712 /* Subroutine of fold_binary. This routine performs all of the
8713 transformations that are common to the equality/inequality
8714 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8715 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8716 fold_binary should call fold_binary. Fold a comparison with
8717 tree code CODE and type TYPE with operands OP0 and OP1. Return
8718 the folded comparison or NULL_TREE. */
8720 static tree
8723 {
8733 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8735 && (equality_code
8742 {
8743 const enum tree_code
8750 /* If the constant operation overflowed this can be
8751 simplified as a comparison against INT_MAX/INT_MIN. */
8754 {
8758 /* Get the sign of the constant on the lhs if the
8759 operation were VARIABLE + CONST1. */
8763 /* The sign of the constant determines if we overflowed
8764 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8765 Canonicalize to the INT_MIN overflow by swapping the comparison
8766 if necessary. */
8770 /* We now can look at the canonicalized case
8771 VARIABLE + 1 CODE2 INT_MIN
8772 and decide on the result. */
8774 {
8778 return
8784 return
8789 }
8790 }
8791 else
8792 {
8795 "when changing X +- C1 cmp C2 to "
8797 WARN_STRICT_OVERFLOW_COMPARISON);
8799 }
8800 }
8802 /* Transform comparisons of the form X - Y CMP 0 to X CMP Y. */
8804 && equality_code
8806 {
8807 /* ??? The transformation is valid for the other operators if overflow
8808 is undefined for the type, but performing it here badly interacts
8809 with the transformation in fold_cond_expr_with_comparison which
8810 attempts to synthetize ABS_EXPR. */
8814 WARN_STRICT_OVERFLOW_COMPARISON);
8817 }
8819 /* For comparisons of pointers we can decompose it to a compile time
8820 comparison of the base objects and the offsets into the object.
8821 This requires at least one operand being an ADDR_EXPR or a
8822 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8828 {
8831 machine_mode mode;
8835 /* Get base and offset for the access. Strip ADDR_EXPR for
8836 get_inner_reference, but put it back by stripping INDIRECT_REF
8837 off the base object if possible. indirect_baseN will be true
8838 if baseN is not an address but refers to the object itself. */
8841 {
8847 else
8849 }
8851 {
8855 {
8858 }
8861 {
8866 {
8869 }
8870 }
8871 }
8875 {
8881 else
8883 }
8885 {
8889 {
8892 }
8895 {
8900 {
8903 }
8904 }
8905 }
8907 /* A local variable can never be pointed to by
8908 the default SSA name of an incoming parameter. */
8910 && indirect_base0
8913 && !indirect_base1
8918 && indirect_base1
8921 && !indirect_base0
8925 {
8930 }
8931 /* If we have equivalent bases we might be able to simplify. */
8934 {
8935 /* We can fold this expression to a constant if the non-constant
8936 offset parts are equal. */
8945 {
8951 "occur when comparing P +- C1 with "
8953 WARN_STRICT_OVERFLOW_CONDITIONAL);
8956 {
8970 }
8971 }
8972 /* We can simplify the comparison to a comparison of the variable
8973 offset parts if the constant offset parts are equal.
8974 Be careful to use signed sizetype here because otherwise we
8975 mess with array offsets in the wrong way. This is possible
8976 because pointer arithmetic is restricted to retain within an
8977 object and overflow on pointer differences is undefined as of
8978 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8980 && (equality_code
8983 {
8984 /* By converting to signed sizetype we cover middle-end pointer
8985 arithmetic which operates on unsigned pointer types of size
8986 type size and ARRAY_REF offsets which are properly sign or
8987 zero extended from their type in case it is narrower than
8988 sizetype. */
8991 else
8995 else
9002 "occur when comparing P +- C1 with "
9004 WARN_STRICT_OVERFLOW_COMPARISON);
9007 }
9008 }
9009 /* For non-equal bases we can simplify if they are addresses
9010 declarations with different addresses. */
9012 /* We know that !operand_equal_p (base0, base1, 0)
9013 because the if condition was false. But make
9014 sure two decls are not the same. */
9020 /* Watch for aliases. */
9025 {
9032 }
9033 /* For equal offsets we can simplify to a comparison of the
9034 base addresses. */
9036 && (indirect_base0
9038 && (indirect_base1
9043 {
9049 }
9050 }
9052 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
9053 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
9054 the resulting offset is smaller in absolute value than the
9055 original one and has the same sign. */
9064 {
9069 tree cst;
9071 "occur when combining constants around "
9074 /* Put the constant on the side where it doesn't overflow and is
9075 of lower absolute value and of same sign than before. */
9082 {
9085 variable1,
9089 }
9097 {
9103 variable2);
9104 }
9105 }
9107 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
9108 signed arithmetic case. That form is created by the compiler
9109 often enough for folding it to be of value. One example is in
9110 computing loop trip counts after Operator Strength Reduction. */
9117 {
9123 /* Handle unfolded multiplication by zero. */
9128 "eliminating multiplication in comparison "
9130 WARN_STRICT_OVERFLOW_COMPARISON);
9132 /* If const1 is negative we swap the sense of the comparison. */
9137 }
9144 {
9152 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
9158 /* (-a) CMP (-b) -> b CMP a */
9165 {
9166 REAL_VALUE_TYPE cst;
9169 /* (-a) CMP CST -> a swap(CMP) (-CST) */
9176 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
9177 /* a CMP (-0) -> a CMP 0 */
9182 /* x != NaN is always true, other ops are always false. */
9185 {
9188 }
9190 /* Fold comparisons against infinity. */
9193 {
9197 }
9198 }
9200 /* If this is a comparison of a real constant with a PLUS_EXPR
9201 or a MINUS_EXPR of a real constant, we can convert it into a
9202 comparison with a revised real constant as long as no overflow
9203 occurs when unsafe_math_optimizations are enabled. */
9215 /* Likewise, we can simplify a comparison of a real constant with
9216 a MINUS_EXPR whose first operand is also a real constant, i.e.
9217 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9218 floating-point types only if -fassociative-math is set. */
9224 arg1))
9229 /* Fold comparisons against built-in math functions. */
9231 && flag_unsafe_math_optimizations
9233 {
9237 {
9241 }
9242 }
9243 }
9247 {
9248 /* If we are widening one operand of an integer comparison,
9249 see if the other operand is similarly being widened. Perhaps we
9250 can do the comparison in the narrower type. */
9255 /* Or if we are changing signedness. */
9259 }
9261 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9262 constant, we can simplify it. */
9267 {
9271 }
9273 /* Simplify comparison of something with itself. (For IEEE
9274 floating-point, we can only do some of these simplifications.) */
9276 {
9278 {
9293 /* For NE, we can only do this simplification if integer
9294 or we don't honor IEEE floating point NaNs. */
9298 /* ... fall through ... */
9304 }
9305 }
9307 /* If we are comparing an expression that just has comparisons
9308 of two integer values, arithmetic expressions of those comparisons,
9309 and constants, we can simplify it. There are only three cases
9310 to check: the two values can either be equal, the first can be
9311 greater, or the second can be greater. Fold the expression for
9312 those three values. Since each value must be 0 or 1, we have
9313 eight possibilities, each of which corresponds to the constant 0
9314 or 1 or one of the six possible comparisons.
9316 This handles common cases like (a > b) == 0 but also handles
9317 expressions like ((x > y) - (y > x)) > 0, which supposedly
9318 occur in macroized code. */
9321 {
9326 /* Don't handle degenerate cases here; they should already
9327 have been handled anyway. */
9336 {
9340 /* We can't just pass T to eval_subst in case cval1 or cval2
9341 was the same as ARG1. */
9343 tree high_result
9347 arg1);
9348 tree equal_result
9352 arg1);
9353 tree low_result
9357 arg1);
9359 /* All three of these results should be 0 or 1. Confirm they are.
9360 Then use those values to select the proper code to use. */
9365 {
9366 /* Make a 3-bit mask with the high-order bit being the
9367 value for `>', the next for '=', and the low for '<'. */
9371 {
9373 /* Always false. */
9394 /* Always true. */
9396 }
9399 {
9403 }
9405 }
9406 }
9407 }
9409 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9410 into a single range test. */
9418 {
9422 }
9424 /* Fold ~X op ~Y as Y op X. */
9427 {
9433 }
9435 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9438 {
9444 }
9447 }
9450 /* Subroutine of fold_binary. Optimize complex multiplications of the
9451 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9452 argument EXPR represents the expression "z" of type TYPE. */
9454 static tree
9456 {
9461 {
9464 }
9466 {
9469 }
9470 else
9471 {
9475 }
9484 }
9487 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9488 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9489 guarantees that P and N have the same least significant log2(M) bits.
9490 N is not otherwise constrained. In particular, N is not normalized to
9491 0 <= N < M as is common. In general, the precise value of P is unknown.
9492 M is chosen as large as possible such that constant N can be determined.
9494 Returns M and sets *RESIDUE to N.
9496 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9497 account. This is not always possible due to PR 35705.
9498 */
9500 static unsigned HOST_WIDE_INT
9503 {
9510 {
9515 }
9517 {
9525 allow_func_align);
9531 {
9534 }
9536 {
9539 {
9542 /* Compute the greatest power-of-2 divisor of op1. */
9546 /* If align is non-zero and less than *modulus, replace
9547 *modulus with align., If align is 0, then either op1 is 0
9548 or the greatest power-of-2 divisor of op1 doesn't fit in an
9549 unsigned HOST_WIDE_INT. In either case, no additional
9550 constraint is imposed. */
9555 }
9556 }
9557 }
9559 /* If we get here, we were unable to determine anything useful about the
9560 expression. */
9562 }
9564 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
9565 CONSTRUCTOR ARG into array ELTS and return true if successful. */
9567 static bool
9569 {
9573 {
9576 }
9578 {
9584 else
9586 }
9587 else
9593 }
9595 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9596 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9597 NULL_TREE otherwise. */
9599 static tree
9601 {
9618 {
9622 }
9625 {
9631 }
9632 else
9634 }
9636 /* Try to fold a pointer difference of type TYPE two address expressions of
9637 array references AREF0 and AREF1 using location LOC. Return a
9638 simplified expression for the difference or NULL_TREE. */
9640 static tree
9643 {
9648 /* If the bases are array references as well, recurse. If the bases
9649 are pointer indirections compute the difference of the pointers.
9650 If the bases are equal, we are set. */
9653 && (base_offset
9661 {
9667 base_offset,
9670 }
9672 }
9674 /* If the real or vector real constant CST of type TYPE has an exact
9675 inverse, return it, else return NULL. */
9677 tree
9679 {
9680 REAL_VALUE_TYPE r;
9682 machine_mode mode;
9686 {
9702 {
9707 }
9713 }
9714 }
9716 /* Mask out the tz least significant bits of X of type TYPE where
9717 tz is the number of trailing zeroes in Y. */
9718 static wide_int
9720 {
9725 }
9727 /* Return true when T is an address and is known to be nonzero.
9728 For floating point we further ensure that T is not denormal.
9729 Similar logic is present in nonzero_address in rtlanal.h.
9731 If the return value is based on the assumption that signed overflow
9732 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9733 change *STRICT_OVERFLOW_P. */
9735 static bool
9737 {
9741 /* Doing something useful for floating point would need more work. */
9747 {
9750 strict_overflow_p);
9756 strict_overflow_p);
9764 }
9767 {
9770 strict_overflow_p);
9778 strict_overflow_p);
9793 strict_overflow_p);
9797 strict_overflow_p);
9800 {
9812 }
9816 }
9818 }
9820 /* Return true when T is an address and is known to be nonzero.
9821 Handle warnings about undefined signed overflow. */
9823 static bool
9825 {
9832 "determining that expression is always "
9834 WARN_STRICT_OVERFLOW_MISC);
9836 }
9838 /* Fold a binary expression of code CODE and type TYPE with operands
9839 OP0 and OP1. LOC is the location of the resulting expression.
9840 Return the folded expression if folding is successful. Otherwise,
9841 return NULL_TREE. */
9843 tree
9846 {
9861 /* Strip any conversions that don't change the mode. This is
9862 safe for every expression, except for a comparison expression
9863 because its signedness is derived from its operands. So, in
9864 the latter case, only strip conversions that don't change the
9865 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9866 preserved.
9868 Note that this is done as an internal manipulation within the
9869 constant folder, in order to find the simplest representation
9870 of the arguments so that their form can be studied. In any
9871 cases, the appropriate type conversions should be put back in
9872 the tree that will get out of the constant folder. */
9875 {
9878 }
9879 else
9880 {
9883 }
9885 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9886 constant but we can't do arithmetic on them. */
9888 {
9891 {
9895 }
9896 }
9898 /* If this is a commutative operation, and ARG0 is a constant, move it
9899 to ARG1 to reduce the number of tests below. */
9904 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9905 to ARG1 to reduce the number of tests below. */
9914 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9916 First check for cases where an arithmetic operation is applied to a
9917 compound, conditional, or comparison operation. Push the arithmetic
9918 operation inside the compound or conditional to see if any folding
9919 can then be done. Convert comparison to conditional for this purpose.
9920 The also optimizes non-constant cases that used to be done in
9921 expand_expr.
9923 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9924 one of the operands is a comparison and the other is a comparison, a
9925 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9926 code below would make the expression more complex. Change it to a
9927 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9928 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9941 {
9945 boolean_type_node,
9953 }
9957 {
9959 {
9964 tem);
9965 }
9968 {
9973 tem);
9974 }
9979 {
9985 }
9990 {
9996 }
9997 }
10000 {
10002 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
10005 {
10011 }
10013 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
10016 {
10017 tree base;
10018 HOST_WIDE_INT coffset;
10027 }
10032 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
10038 arg1),
10040 arg0)));
10046 {
10047 /* X + (X / CST) * -CST is X % CST. */
10052 {
10061 cst0));
10062 }
10063 }
10065 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
10066 one. Make sure the type is not saturating and has the signedness of
10067 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10068 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10075 {
10079 }
10082 {
10083 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
10084 with a constant, and the two constants have no bits in common,
10085 we should treat this as a BIT_IOR_EXPR since this may produce more
10086 simplifications. */
10093 {
10096 }
10098 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
10099 (plus (plus (mult) (mult)) (foo)) so that we can
10100 take advantage of the factoring cases below. */
10109 {
10115 else
10128 parg0),
10130 marg)),
10134 return
10140 parg1)));
10141 }
10142 }
10143 else
10144 {
10145 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
10146 to __complex__ ( x, y ). This is not the same for SNaNs or
10147 if signed zeros are involved. */
10151 {
10158 {
10162 {
10168 }
10170 {
10176 }
10177 }
10178 }
10186 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
10187 We associate floats only if the user has specified
10188 -fassociative-math. */
10192 {
10197 {
10198 tree tree0;
10201 }
10202 }
10203 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
10204 We associate floats only if the user has specified
10205 -fassociative-math. */
10209 {
10214 {
10215 tree tree0;
10218 }
10219 }
10220 }
10222 bit_rotate:
10223 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
10224 is a rotate of A by C1 bits. */
10225 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
10226 is a rotate of A by B bits. */
10227 {
10229 tree rtype;
10238 /* Only create rotates in complete modes. Other cases are not
10239 expanded properly. */
10242 {
10256 {
10262 }
10264 {
10272 element_precision
10276 return
10279 ? LROTATE_EXPR
10283 }
10285 {
10293 element_precision
10297 return fold_convert_loc
10300 ? LROTATE_EXPR
10304 }
10305 }
10306 }
10308 associate:
10309 /* In most languages, can't associate operations on floats through
10310 parentheses. Rather than remember where the parentheses were, we
10311 don't associate floats at all, unless the user has specified
10312 -fassociative-math.
10313 And, we need to make sure type is not saturating. */
10317 {
10323 /* Split both trees into variables, constants, and literals. Then
10324 associate each group together, the constants with literals,
10325 then the result with variables. This increases the chances of
10326 literals being recombined later and of generating relocatable
10327 expressions for the sum of a constant and literal. */
10332 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10336 /* With undefined overflow prefer doing association in a type
10337 which wraps on overflow, if that is one of the operand types. */
10340 {
10348 }
10350 /* With undefined overflow we can only associate constants with one
10351 variable, and constants whose association doesn't overflow. */
10354 {
10356 {
10374 /* The only case we can still associate with two variables
10375 is if they are the same, modulo negation and bit-pattern
10376 preserving conversions. */
10379 }
10380 }
10382 /* Only do something if we found more than two objects. Otherwise,
10383 nothing has changed and we risk infinite recursion. */
10389 {
10401 /* Preserve the MINUS_EXPR if the negative part of the literal is
10402 greater than the positive part. Otherwise, the multiplicative
10403 folding code (i.e extract_muldiv) may be fooled in case
10404 unsigned constants are subtracted, like in the following
10405 example: ((X*2 + 4) - 8U)/2. */
10407 {
10411 {
10415 }
10416 else
10417 {
10421 }
10422 }
10424 /* Don't introduce overflows through reassociation. */
10431 {
10433 return
10437 else
10438 {
10441 return
10445 }
10446 }
10449 return
10452 }
10453 }
10458 /* Pointer simplifications for subtraction, simple reassociations. */
10460 {
10461 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10464 {
10474 }
10475 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10477 {
10484 }
10485 /* PTR0 - (PTR1 p+ A) -> (PTR0 - PTR1) - A, assuming PTR0 - PTR1
10486 simplifies. */
10488 {
10495 arg10);
10498 }
10499 }
10500 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10510 /* X - (X / Y) * Y is X % Y. */
10518 return
10524 {
10525 /* Fold A - (A & B) into ~B & A. */
10528 {
10530 {
10537 }
10539 {
10546 }
10547 }
10549 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10550 any power of 2 minus 1. */
10555 {
10561 {
10565 }
10566 }
10567 }
10569 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10570 __complex__ ( x, -y ). This is not the same for SNaNs or if
10571 signed zeros are involved. */
10575 {
10582 {
10586 {
10588 arg1r ? arg1r
10593 }
10595 {
10599 arg1i ? arg1i
10602 }
10603 }
10604 }
10606 /* A - B -> A + (-B) if B is easily negatable. */
10610 /* Avoid this transformation if B is a positive REAL_CST. */
10619 /* Try folding difference of addresses. */
10620 {
10621 HOST_WIDE_INT diff;
10627 }
10629 /* Fold &a[i] - &a[j] to i-j. */
10634 {
10640 }
10643 && flag_unsafe_math_optimizations
10649 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10650 one. Make sure the type is not saturating and has the signedness of
10651 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10652 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10659 {
10663 }
10668 /* (-A) * (-B) -> A * B */
10683 {
10684 /* Transform x * -C into -x * C if x is easily negatable. */
10693 tem);
10695 /* (a * (1 << b)) is (a << b) */
10705 /* (A + A) * C -> A * 2 * C */
10717 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
10718 sign-changing only. */
10728 {
10731 "occur when simplifying "
10733 WARN_STRICT_OVERFLOW_MISC);
10735 }
10737 /* Optimize z * conj(z) for integer complex numbers. */
10744 }
10745 else
10746 {
10747 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10748 the result for floating point types due to rounding so it is applied
10749 only if -fassociative-math was specify. */
10754 {
10756 arg1);
10760 }
10762 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10764 {
10767 {
10770 }
10771 }
10773 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10774 This is not the same for NaNs or if signed zeros are
10775 involved. */
10781 {
10784 return
10790 return
10795 }
10797 /* Optimize z * conj(z) for floating point complex numbers.
10798 Guarded by flag_unsafe_math_optimizations as non-finite
10799 imaginary components don't produce scalar results. */
10810 {
10814 /* Optimizations of root(...)*root(...). */
10816 {
10821 /* Optimize sqrt(x)*sqrt(x) as x. */
10827 /* Optimize root(x)*root(y) as root(x*y). */
10831 }
10833 /* Optimize expN(x)*expN(y) as expN(x+y). */
10835 {
10841 }
10843 /* Optimizations of pow(...)*pow(...). */
10847 {
10853 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10855 {
10860 }
10862 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10864 {
10869 }
10870 }
10872 /* Optimize tan(x)*cos(x) as sin(x). */
10881 {
10887 }
10889 /* Optimize x*pow(x,c) as pow(x,c+1). */
10893 {
10899 {
10901 REAL_VALUE_TYPE c;
10902 tree arg;
10908 }
10909 }
10911 /* Optimize pow(x,c)*x as pow(x,c+1). */
10915 {
10921 {
10923 REAL_VALUE_TYPE c;
10924 tree arg;
10930 }
10931 }
10933 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
10935 && optimize
10937 {
10941 {
10944 }
10945 }
10946 }
10947 }
10951 bit_ior:
10952 /* ~X | X is -1. */
10955 {
10959 }
10961 /* X | ~X is -1. */
10964 {
10968 }
10970 /* Canonicalize (X & C1) | C2. */
10974 {
10979 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10987 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10992 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10993 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10994 mode which allows further optimizations. */
10999 {
11003 {
11006 }
11007 }
11014 c3)),
11015 arg1);
11016 }
11018 /* (X & ~Y) | (~X & Y) is X ^ Y */
11021 {
11038 }
11044 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
11046 This results in more efficient code for machines without a NAND
11047 instruction. Combine will canonicalize to the first form
11048 which will allow use of NAND instructions provided by the
11049 backend if they exist. */
11052 {
11053 return
11060 }
11062 /* See if this can be simplified into a rotate first. If that
11063 is unsuccessful continue in the association code. */
11067 /* ~X ^ X is -1. */
11070 {
11074 }
11076 /* X ^ ~X is -1. */
11079 {
11083 }
11085 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
11086 with a constant, and the two constants have no bits in common,
11087 we should treat this as a BIT_IOR_EXPR since this may produce more
11088 simplifications. */
11095 {
11098 }
11100 /* (X | Y) ^ X -> Y & ~ X*/
11103 {
11106 arg1);
11111 }
11113 /* (Y | X) ^ X -> Y & ~ X*/
11116 {
11119 arg1);
11124 }
11126 /* X ^ (X | Y) -> Y & ~ X*/
11129 {
11132 arg0);
11137 }
11139 /* X ^ (Y | X) -> Y & ~ X*/
11142 {
11145 arg0);
11150 }
11152 /* Convert ~X ^ ~Y to X ^ Y. */
11161 /* Convert ~X ^ C to X ^ ~C. */
11169 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
11177 /* Fold (X & Y) ^ Y as ~X & Y. */
11180 {
11185 }
11186 /* Fold (X & Y) ^ X as ~Y & X. */
11190 {
11195 }
11196 /* Fold X ^ (X & Y) as X & ~Y. */
11199 {
11204 }
11205 /* Fold X ^ (Y & X) as ~Y & X. */
11209 {
11214 }
11216 /* See if this can be simplified into a rotate first. If that
11217 is unsuccessful continue in the association code. */
11221 /* ~X & X, (X == 0) & X, and !X & X are always zero. */
11229 /* X & ~X , X & (X == 0), and X & !X are always zero. */
11237 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
11242 {
11243 tree tem2;
11250 }
11251 /* Fold ~X & 1 as (X & 1) == 0. */
11255 {
11256 tree tem2;
11263 }
11264 /* Fold !X & 1 as X == 0. */
11267 {
11271 }
11273 /* Fold (X ^ Y) & Y as ~X & Y. */
11276 {
11281 }
11282 /* Fold (X ^ Y) & X as ~Y & X. */
11286 {
11291 }
11292 /* Fold X & (X ^ Y) as X & ~Y. */
11295 {
11300 }
11301 /* Fold X & (Y ^ X) as ~Y & X. */
11305 {
11310 }
11312 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
11313 multiple of 1 << CST. */
11315 {
11322 }
11324 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
11325 bits from CST2. */
11329 {
11337 {
11338 /* Avoid the transform if arg1 is a mask of some
11339 mode which allows further optimizations. */
11346 }
11347 }
11349 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11350 ((A & N) + B) & M -> (A + B) & M
11351 Similarly if (N & M) == 0,
11352 ((A | N) + B) & M -> (A + B) & M
11353 and for - instead of + (or unary - instead of +)
11354 and/or ^ instead of |.
11355 If B is constant and (B & M) == 0, fold into A & M. */
11357 {
11366 {
11369 wide_int cst0;
11371 /* Now we know that arg0 is (C + D) or (C - D) or
11372 -C and arg1 (M) is == (1LL << cst) - 1.
11373 Store C into PMOP[0] and D into PMOP[1]. */
11377 {
11380 }
11387 {
11397 {
11400 }
11403 /* If C or D is of the form (A & N) where
11404 (N & M) == M, or of the form (A | N) or
11405 (A ^ N) where (N & M) == 0, replace it with A. */
11409 /* If C or D is a N where (N & M) == 0, it can be
11410 omitted (assumed 0). */
11418 }
11420 /* Only build anything new if we optimized one or both arguments
11421 above. */
11425 {
11428 {
11429 /* Perform the operations in a type that has defined
11430 overflow behavior. */
11436 }
11441 {
11449 else
11451 }
11454 else
11457 /* TEM is now the new binary +, - or unary - replacement. */
11461 }
11462 }
11463 }
11468 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11471 {
11476 return
11478 }
11480 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11482 This results in more efficient code for machines without a NOR
11483 instruction. Combine will canonicalize to the first form
11484 which will allow use of NOR instructions provided by the
11485 backend if they exist. */
11488 {
11495 }
11497 /* If arg0 is derived from the address of an object or function, we may
11498 be able to fold this expression using the object or function's
11499 alignment. */
11501 {
11508 /* This works because modulus is a power of 2. If this weren't the
11509 case, we'd have to replace it by its greatest power-of-2
11510 divisor: modulus & -modulus. */
11513 }
11515 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11516 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11517 if the new mask might be further optimized. */
11526 {
11537 {
11540 /* See if more bits can be proven as zero because of
11541 zero extension. */
11544 {
11549 {
11551 /* See if we can shorten the right shift. */
11554 /* Otherwise X >> C1 is all zeros, so we'll optimize
11555 it into (X, 0) later on by making sure zerobits
11556 is all ones. */
11557 }
11558 }
11561 {
11564 }
11565 /* For arithmetic shift if sign bit could be set, zerobits
11566 can contain actually sign bits, so no transformation is
11567 possible, unless MASK masks them all away. In that
11568 case the shift needs to be converted into logical shift. */
11571 {
11574 else
11576 }
11577 }
11579 /* ((X << 16) & 0xff00) is (X, 0). */
11586 {
11587 /* Only do the transformation if NEWMASK is some integer
11588 mode's mask. */
11595 {
11596 tree newmaskt;
11599 {
11605 }
11606 else
11611 }
11612 }
11613 }
11618 /* Don't touch a floating-point divide by zero unless the mode
11619 of the constant can represent infinity. */
11625 /* (-A) / (-B) -> A / B */
11635 /* Convert A/B/C to A/(B*C). */
11642 /* Convert A/(B/C) to (A/B)*C. */
11650 /* Convert C1/(X*C2) into (C1/C2)/X. */
11655 {
11661 }
11664 {
11668 /* Optimize sin(x)/cos(x) as tan(x). */
11674 {
11679 }
11681 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11687 {
11691 {
11696 }
11697 }
11699 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11700 NaNs or Infinities. */
11704 {
11711 {
11716 }
11717 }
11719 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11720 NaNs or Infinities. */
11724 {
11731 {
11735 {
11739 tmp);
11740 }
11741 }
11742 }
11744 /* Optimize pow(x,c)/x as pow(x,c-1). */
11748 {
11754 {
11756 REAL_VALUE_TYPE c;
11757 tree arg;
11763 }
11764 }
11766 /* Optimize a/root(b/c) into a*root(c/b). */
11768 {
11772 {
11781 }
11782 }
11784 /* Optimize x/expN(y) into x*expN(-y). */
11786 {
11793 }
11795 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11799 {
11807 }
11808 }
11812 /* Optimize (X & (-A)) / A where A is a power of 2,
11813 to X >> log2(A) */
11817 {
11825 }
11826 }
11828 /* Fall through */
11831 /* Simplify A / (B << N) where A and B are positive and B is
11832 a power of 2, to A >> (N + log2(B)). */
11837 {
11840 {
11848 WARN_STRICT_OVERFLOW_MISC);
11854 }
11855 }
11857 /* Fall through */
11865 /* Convert -A / -B to A / B when the type is signed and overflow is
11866 undefined. */
11870 {
11873 "when distributing negation across "
11875 WARN_STRICT_OVERFLOW_MISC);
11881 }
11885 {
11888 "when distributing negation across "
11890 WARN_STRICT_OVERFLOW_MISC);
11896 }
11898 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11899 operation, EXACT_DIV_EXPR.
11901 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11902 At one time others generated faster code, it's not clear if they do
11903 after the last round to changes to the DIV code in expmed.c. */
11912 {
11916 WARN_STRICT_OVERFLOW_MISC);
11918 }
11926 /* X % -Y is the same as X % Y. */
11939 {
11943 WARN_STRICT_OVERFLOW_MISC);
11945 }
11947 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11948 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11952 {
11954 /* Also optimize A % (C << N) where C is a power of 2,
11955 to A & ((C << N) - 1). */
11960 {
11961 tree mask
11966 "occur when simplifying "
11968 WARN_STRICT_OVERFLOW_MISC);
11972 }
11973 }
11981 /* Since negative shift count is not well-defined,
11982 don't try to compute it in the compiler. */
11988 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11993 {
11997 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11998 being well defined. */
12000 {
12006 else
12008 }
12012 }
12014 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
12015 into x & ((unsigned)-1 >> c) for unsigned types. */
12023 {
12026 tree lshift;
12027 tree arg00;
12030 {
12037 }
12038 }
12040 /* If we have a rotate of a bit operation with the rotate count and
12041 the second operand of the bit operation both constant,
12042 permute the two operations. */
12054 /* Two consecutive rotates adding up to the some integer
12055 multiple of the precision of the type can be ignored. */
12063 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
12064 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
12065 if the latter can be further optimized. */
12070 {
12074 arg1);
12078 arg1);
12082 }
12099 /* Note that the operands of this must be ints
12100 and their values must be 0 or 1.
12101 ("true" is a fixed value perhaps depending on the language.) */
12102 /* If first arg is constant zero, return it. */
12106 /* If either arg is constant true, drop it. */
12110 /* Preserve sequence points. */
12113 /* If second arg is constant zero, result is zero, but first arg
12114 must be evaluated. */
12117 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
12118 case will be handled here. */
12122 /* !X && X is always false. */
12126 /* X && !X is always false. */
12131 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12132 means A >= Y && A != MAX, but in this case we know that
12133 A < X <= MAX. */
12137 {
12145 }
12154 /* Note that the operands of this must be ints
12155 and their values must be 0 or true.
12156 ("true" is a fixed value perhaps depending on the language.) */
12157 /* If first arg is constant true, return it. */
12161 /* If either arg is constant zero, drop it. */
12165 /* Preserve sequence points. */
12168 /* If second arg is constant true, result is true, but we must
12169 evaluate first arg. */
12172 /* Likewise for first arg, but note this only occurs here for
12173 TRUTH_OR_EXPR. */
12177 /* !X || X is always true. */
12181 /* X || !X is always true. */
12186 /* (X && !Y) || (!X && Y) is X ^ Y */
12189 {
12206 }
12215 /* If the second arg is constant zero, drop it. */
12218 /* If the second arg is constant true, this is a logical inversion. */
12220 {
12223 }
12224 /* Identical arguments cancel to zero. */
12228 /* !X ^ X is always true. */
12233 /* X ^ !X is always true. */
12249 /* bool_var != 0 becomes bool_var. */
12254 /* bool_var == 1 becomes bool_var. */
12259 /* bool_var != 1 becomes !bool_var. */
12266 /* bool_var == 0 becomes !bool_var. */
12273 /* !exp != 0 becomes !exp */
12278 /* If this is an equality comparison of the address of two non-weak,
12279 unaliased symbols neither of which are extern (since we do not
12280 have access to attributes for externs), then we know the result. */
12285 {
12293 else
12298 type);
12299 }
12301 /* Similarly for a NEGATE_EXPR. */
12305 arg1)))
12310 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12318 arg1),
12321 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12330 {
12334 val,
12338 }
12340 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12347 {
12349 code == NE_EXPR
12352 }
12354 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12359 /* If this is an EQ or NE comparison with zero and ARG0 is
12360 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12361 two operations, but the latter can be done in one less insn
12362 on machines that have only two-operand insns or on which a
12363 constant cannot be the first operand. */
12366 {
12371 {
12378 arg1);
12379 }
12382 {
12389 arg1);
12390 }
12391 }
12393 /* If this is an NE or EQ comparison of zero against the result of a
12394 signed MOD operation whose second operand is a power of 2, make
12395 the MOD operation unsigned since it is simpler and equivalent. */
12403 {
12413 }
12415 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12416 C1 is a valid shift constant, and C2 is a power of two, i.e.
12417 a single bit. */
12421 == INTEGER_CST
12424 {
12429 /* Check for a valid shift count. */
12431 {
12435 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12436 can be rewritten as (X & (C2 << C1)) != 0. */
12438 {
12443 }
12444 /* Otherwise, for signed (arithmetic) shifts,
12445 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12446 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12450 /* Otherwise, of unsigned (logical) shifts,
12451 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12452 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12453 else
12457 arg000);
12458 }
12459 }
12461 /* If we have (A & C) == C where C is a power of 2, convert this into
12462 (A & C) != 0. Similarly for NE_EXPR. */
12468 integer_zero_node));
12470 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12471 bit, then fold the expression into A < 0 or A >= 0. */
12476 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12477 Similarly for NE_EXPR. */
12481 {
12485 tree dandnotc
12488 notc);
12492 }
12494 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12495 Similarly for NE_EXPR. */
12499 {
12501 tree candnotd
12508 }
12510 /* If this is a comparison of a field, we may be able to simplify it. */
12513 /* Handle the constant case even without -O
12514 to make sure the warnings are given. */
12516 {
12520 }
12522 /* Optimize comparisons of strlen vs zero to a compare of the
12523 first character of the string vs zero. To wit,
12524 strlen(ptr) == 0 => *ptr == 0
12525 strlen(ptr) != 0 => *ptr != 0
12526 Other cases should reduce to one of these two (or a constant)
12527 due to the return value of strlen being unsigned. */
12530 {
12538 {
12543 }
12544 }
12546 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12547 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12551 {
12556 {
12558 {
12561 }
12564 }
12565 }
12567 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12573 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12578 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12585 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12593 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12594 (X & C) == 0 when C is a single bit. */
12599 {
12606 arg1));
12607 }
12609 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12610 constant C is a power of two, i.e. a single bit. */
12617 {
12621 }
12623 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12624 when is C is a power of two, i.e. a single bit. */
12631 {
12637 }
12641 {
12644 }
12646 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12654 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12657 {
12670 arg01),
12679 arg01),
12688 arg00),
12697 arg00),
12699 }
12703 {
12710 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12711 operand_equal_p guarantees no side-effects so we don't need
12712 to use omit_one_operand on Z. */
12716 arg10));
12720 arg11));
12724 arg10));
12728 arg11));
12730 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12733 {
12739 }
12740 }
12742 /* Attempt to simplify equality/inequality comparisons of complex
12743 values. Only lower the comparison if the result is known or
12744 can be simplified to a single scalar comparison. */
12749 {
12754 {
12757 }
12758 else
12759 {
12762 }
12765 {
12768 }
12769 else
12770 {
12773 }
12777 {
12779 {
12784 }
12785 else
12786 {
12791 }
12792 }
12796 {
12798 {
12803 }
12804 else
12805 {
12810 }
12811 }
12812 }
12824 /* Transform comparisons of the form X +- C CMP X. */
12831 {
12838 else
12841 /* (X - c) > X becomes false. */
12845 {
12849 "occur when assuming that (X - c) > X "
12851 WARN_STRICT_OVERFLOW_ALL);
12853 }
12855 /* Likewise (X + c) < X becomes false. */
12859 {
12863 "occur when assuming that "
12865 WARN_STRICT_OVERFLOW_ALL);
12867 }
12869 /* Convert (X - c) <= X to true. */
12874 {
12878 "occur when assuming that "
12880 WARN_STRICT_OVERFLOW_ALL);
12882 }
12884 /* Convert (X + c) >= X to true. */
12889 {
12893 "occur when assuming that "
12895 WARN_STRICT_OVERFLOW_ALL);
12897 }
12900 {
12901 /* Convert X + c > X and X - c < X to true for integers. */
12905 {
12908 "not occur when assuming that "
12910 WARN_STRICT_OVERFLOW_ALL);
12912 }
12917 {
12920 "not occur when assuming that "
12922 WARN_STRICT_OVERFLOW_ALL);
12924 }
12926 /* Convert X + c <= X and X - c >= X to false for integers. */
12930 {
12933 "not occur when assuming that "
12935 WARN_STRICT_OVERFLOW_ALL);
12937 }
12942 {
12945 "not occur when assuming that "
12947 WARN_STRICT_OVERFLOW_ALL);
12949 }
12950 }
12951 }
12953 /* Comparisons with the highest or lowest possible integer of
12954 the specified precision will have known values. */
12955 {
12961 {
12968 {
12981 /* The GE_EXPR and LT_EXPR cases above are not normally
12982 reached because of previous transformations. */
12986 }
12989 {
12996 arg1);
13002 arg0),
13003 arg1);
13006 }
13009 {
13024 }
13027 {
13034 arg1);
13040 arg0),
13041 arg1);
13044 }
13048 /* We will flip the signedness of the comparison operator
13049 associated with the mode of arg1, so the sign bit is
13050 specified by this mode. Check that arg1 is the signed
13051 max associated with this sign bit. */
13053 /* signed_type does not work on pointer types. */
13055 {
13056 /* The following case also applies to X < signed_max+1
13057 and X >= signed_max+1 because previous transformations. */
13059 {
13065 }
13066 }
13067 }
13068 }
13070 /* If we are comparing an ABS_EXPR with a constant, we can
13071 convert all the cases into explicit comparisons, but they may
13072 well not be faster than doing the ABS and one comparison.
13073 But ABS (X) <= C is a range comparison, which becomes a subtraction
13074 and a comparison, and is probably faster. */
13088 /* Convert ABS_EXPR<x> >= 0 to true. */
13095 {
13098 "when simplifying comparison of "
13100 WARN_STRICT_OVERFLOW_CONDITIONAL);
13103 arg0);
13104 }
13106 /* Convert ABS_EXPR<x> < 0 to false. */
13111 {
13114 "when simplifying comparison of "
13116 WARN_STRICT_OVERFLOW_CONDITIONAL);
13119 arg0);
13120 }
13122 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13123 and similarly for >= into !=. */
13133 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
13134 otherwise Y might be >= # of bits in X's type and thus e.g.
13135 (unsigned char) (1 << Y) for Y 15 might be 0.
13136 If the cast is widening, then 1 << Y should have unsigned type,
13137 otherwise if Y is number of bits in the signed shift type minus 1,
13138 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
13139 31 might be 0xffffffff80000000. */
13150 {
13156 }
13169 {
13173 }
13175 /* If the first operand is NaN, the result is constant. */
13179 {
13181 ? integer_zero_node
13184 }
13186 /* If the second operand is NaN, the result is constant. */
13190 {
13192 ? integer_zero_node
13195 }
13197 /* Simplify unordered comparison of something with itself. */
13203 && !flag_trapping_math
13207 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13208 {
13220 }
13225 /* When pedantic, a compound expression can be neither an lvalue
13226 nor an integer constant expression. */
13229 /* Don't let (0, 0) be null pointer constant. */
13235 /* An ASSERT_EXPR should never be passed to fold_binary. */
13241 }
13243 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13244 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13245 of GOTO_EXPR. */
13247 static tree
13249 {
13251 {
13258 /* ... fall through ... */
13262 }
13263 }
13265 /* Return whether the sub-tree ST contains a label which is accessible from
13266 outside the sub-tree. */
13268 static bool
13270 {
13271 return
13273 }
13275 /* Fold a ternary expression of code CODE and type TYPE with operands
13276 OP0, OP1, and OP2. Return the folded expression if folding is
13277 successful. Otherwise, return NULL_TREE. */
13279 tree
13282 {
13283 tree tem;
13290 /* If this is a commutative operation, and OP0 is a constant, move it
13291 to OP1 to reduce the number of tests below. */
13300 /* Strip any conversions that don't change the mode. This is safe
13301 for every expression, except for a comparison expression because
13302 its signedness is derived from its operands. So, in the latter
13303 case, only strip conversions that don't change the signedness.
13305 Note that this is done as an internal manipulation within the
13306 constant folder, in order to find the simplest representation of
13307 the arguments so that their form can be studied. In any cases,
13308 the appropriate type conversions should be put back in the tree
13309 that will get out of the constant folder. */
13311 {
13314 }
13317 {
13320 }
13323 {
13326 }
13329 {
13333 {
13339 }
13344 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13345 so all simple results must be passed through pedantic_non_lvalue. */
13347 {
13350 /* Only optimize constant conditions when the selected branch
13351 has the same type as the COND_EXPR. This avoids optimizing
13352 away "c ? x : throw", where the throw has a void type.
13353 Avoid throwing away that operand which contains label. */
13360 }
13362 {
13367 {
13372 {
13380 }
13384 }
13385 }
13387 /* If we have A op B ? A : C, we may be able to convert this to a
13388 simpler expression, depending on the operation and the values
13389 of B and C. Signed zeros prevent all of these transformations,
13390 for reasons given above each one.
13392 Also try swapping the arguments and inverting the conditional. */
13397 {
13401 }
13405 op2,
13408 {
13412 {
13416 }
13417 }
13419 /* If the second operand is simpler than the third, swap them
13420 since that produces better jump optimization results. */
13423 {
13425 /* See if this can be inverted. If it can't, possibly because
13426 it was a floating-point inequality comparison, don't do
13427 anything. */
13431 }
13433 /* Convert A ? 1 : 0 to simply A. */
13438 /* If we try to convert OP0 to our type, the
13439 call to fold will try to move the conversion inside
13440 a COND, which will recurse. In that case, the COND_EXPR
13441 is probably the best choice, so leave it alone. */
13445 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13446 over COND_EXPR in cases such as floating point comparisons. */
13455 arg0)));
13457 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13462 {
13463 /* sign_bit_p looks through both zero and sign extensions,
13464 but for this optimization only sign extensions are
13465 usable. */
13468 {
13471 {
13474 }
13476 }
13477 /* sign_bit_p only checks ARG1 bits within A's precision.
13478 If <sign bit of A> has wider type than A, bits outside
13479 of A's precision in <sign bit of A> need to be checked.
13480 If they are all 0, this optimization needs to be done
13481 in unsigned A's type, if they are all 1 in signed A's type,
13482 otherwise this can't be done. */
13488 {
13490 tree tem_type;
13503 {
13506 }
13508 {
13511 }
13512 else
13514 }
13517 return
13523 arg1)));
13524 }
13526 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13527 already handled above. */
13532 {
13541 }
13543 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13544 is probably obsolete because the first operand should be a
13545 truth value (that's why we have the two cases above), but let's
13546 leave it in until we can confirm this for all front-ends. */
13558 /* Disable the transformations below for vectors, since
13559 fold_binary_op_with_conditional_arg may undo them immediately,
13560 yielding an infinite loop. */
13564 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13573 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13578 {
13580 /* Only perform transformation if ARG0 is easily inverted. */
13584 ? BIT_IOR_EXPR
13587 arg1);
13588 }
13590 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13595 {
13597 /* Only perform transformation if ARG0 is easily inverted. */
13603 op2);
13604 }
13606 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13618 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13619 of fold_ternary on them. */
13629 {
13639 {
13644 {
13652 }
13654 /* Constructor elements can be subvectors. */
13657 {
13661 }
13663 /* We keep an exact subset of the constructor elements. */
13665 {
13671 {
13675 }
13683 CONSTRUCTOR_ELT
13686 }
13687 /* The bitfield references a single constructor element. */
13689 {
13694 else
13698 }
13699 }
13700 }
13702 /* A bit-field-ref that referenced the full argument can be stripped. */
13708 /* On constants we can use native encode/interpret to constant
13709 fold (nearly) all BIT_FIELD_REFs. */
13713 /* This limitation should not be necessary, we just need to
13714 round this up to mode size. */
13716 /* Need bit-shifting of the buffer to relax the following. */
13718 {
13723 /* ??? We cannot tell native_encode_expr to start at
13724 some random byte only. So limit us to a reasonable amount
13725 of work. */
13727 {
13732 {
13738 }
13739 }
13740 }
13745 /* For integers we can decompose the FMA if possible. */
13757 {
13773 {
13778 /* Make sure that the perm value is in an acceptable
13779 range. */
13788 else
13793 }
13796 {
13801 }
13806 {
13811 }
13817 {
13821 }
13826 /* Some targets are deficient and fail to expand a single
13827 argument permutation while still allowing an equivalent
13828 2-argument version. */
13832 {
13835 }
13838 {
13845 }
13849 }
13855 }
13857 /* Perform constant folding and related simplification of EXPR.
13858 The related simplifications include x*1 => x, x*0 => 0, etc.,
13859 and application of the associative law.
13860 NOP_EXPR conversions may be removed freely (as long as we
13861 are careful not to change the type of the overall expression).
13862 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13863 but we can constant-fold them if they have constant operands. */
13865 #ifdef ENABLE_FOLD_CHECKING
13866 # define fold(x) fold_1 (x)
13868 static
13869 #endif
13870 tree
13872 {
13876 tree tem;
13879 /* Return right away if a constant. */
13883 /* CALL_EXPR-like objects with variable numbers of operands are
13884 treated specially. */
13886 {
13888 {
13891 }
13893 }
13896 {
13901 {
13919 }
13920 }
13923 {
13925 {
13932 {
13937 /* Find a matching index by means of a binary search. */
13939 {
13955 else
13957 }
13958 }
13961 }
13963 /* Return a VECTOR_CST if possible. */
13965 {
13972 tree value;
13975 {
13979 {
13982 }
13983 else
13985 }
13990 }
13998 }
14000 #ifdef ENABLE_FOLD_CHECKING
14001 #undef fold
14008 /* When --enable-checking=fold, compute a digest of expr before
14009 and after actual fold call to see if fold did not accidentally
14010 change original expr. */
14012 tree
14014 {
14015 tree ret;
14035 }
14037 void
14039 {
14050 }
14052 static void
14054 {
14056 }
14058 static void
14061 {
14067 recursive_label:
14077 {
14078 /* Allow DECL_ASSEMBLER_NAME to be modified. */
14082 }
14089 {
14090 /* Allow these fields to be modified. */
14091 tree tmp;
14099 {
14102 }
14103 }
14114 {
14117 {
14132 }
14136 {
14149 }
14166 {
14172 }
14175 {
14177 {
14180 }
14182 }
14193 {
14196 }
14206 }
14207 }
14209 /* Helper function for outputting the checksum of a tree T. When
14210 debugging with gdb, you can "define mynext" to be "next" followed
14211 by "call debug_fold_checksum (op0)", then just trace down till the
14212 outputs differ. */
14214 DEBUG_FUNCTION void
14216 {
14231 }
14233 #endif
14235 /* Fold a unary tree expression with code CODE of type TYPE with an
14236 operand OP0. LOC is the location of the resulting expression.
14237 Return a folded expression if successful. Otherwise, return a tree
14238 expression with code CODE of type TYPE with an operand OP0. */
14240 tree
14243 {
14244 tree tem;
14245 #ifdef ENABLE_FOLD_CHECKING
14254 #endif
14260 #ifdef ENABLE_FOLD_CHECKING
14267 #endif
14269 }
14271 /* Fold a binary tree expression with code CODE of type TYPE with
14272 operands OP0 and OP1. LOC is the location of the resulting
14273 expression. Return a folded expression if successful. Otherwise,
14274 return a tree expression with code CODE of type TYPE with operands
14275 OP0 and OP1. */
14277 tree
14280 MEM_STAT_DECL)
14281 {
14282 tree tem;
14283 #ifdef ENABLE_FOLD_CHECKING
14300 #endif
14306 #ifdef ENABLE_FOLD_CHECKING
14321 #endif
14323 }
14325 /* Fold a ternary tree expression with code CODE of type TYPE with
14326 operands OP0, OP1, and OP2. Return a folded expression if
14327 successful. Otherwise, return a tree expression with code CODE of
14328 type TYPE with operands OP0, OP1, and OP2. */
14330 tree
14333 {
14334 tree tem;
14335 #ifdef ENABLE_FOLD_CHECKING
14359 #endif
14366 #ifdef ENABLE_FOLD_CHECKING
14389 #endif
14391 }
14393 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14394 arguments in ARGARRAY, and a null static chain.
14395 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14396 of type TYPE from the given operands as constructed by build_call_array. */
14398 tree
14401 {
14402 tree tem;
14403 #ifdef ENABLE_FOLD_CHECKING
14422 #endif
14428 #ifdef ENABLE_FOLD_CHECKING
14444 #endif
14446 }
14448 /* Perform constant folding and related simplification of initializer
14449 expression EXPR. These behave identically to "fold_buildN" but ignore
14450 potential run-time traps and exceptions that fold must preserve. */
14452 #define START_FOLD_INIT \
14453 int saved_signaling_nans = flag_signaling_nans;\
14454 int saved_trapping_math = flag_trapping_math;\
14455 int saved_rounding_math = flag_rounding_math;\
14456 int saved_trapv = flag_trapv;\
14457 int saved_folding_initializer = folding_initializer;\
14458 flag_signaling_nans = 0;\
14459 flag_trapping_math = 0;\
14460 flag_rounding_math = 0;\
14461 flag_trapv = 0;\
14462 folding_initializer = 1;
14464 #define END_FOLD_INIT \
14465 flag_signaling_nans = saved_signaling_nans;\
14466 flag_trapping_math = saved_trapping_math;\
14467 flag_rounding_math = saved_rounding_math;\
14468 flag_trapv = saved_trapv;\
14469 folding_initializer = saved_folding_initializer;
14471 tree
14474 {
14475 tree result;
14476 START_FOLD_INIT;
14480 END_FOLD_INIT;
14482 }
14484 tree
14487 {
14488 tree result;
14489 START_FOLD_INIT;
14493 END_FOLD_INIT;
14495 }
14497 tree
14500 {
14501 tree result;
14502 START_FOLD_INIT;
14506 END_FOLD_INIT;
14508 }
14510 #undef START_FOLD_INIT
14511 #undef END_FOLD_INIT
14513 /* Determine if first argument is a multiple of second argument. Return 0 if
14514 it is not, or we cannot easily determined it to be.
14516 An example of the sort of thing we care about (at this point; this routine
14517 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14518 fold cases do now) is discovering that
14520 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14522 is a multiple of
14524 SAVE_EXPR (J * 8)
14526 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14528 This code also handles discovering that
14530 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14532 is a multiple of 8 so we don't have to worry about dealing with a
14533 possible remainder.
14535 Note that we *look* inside a SAVE_EXPR only to determine how it was
14536 calculated; it is not safe for fold to do much of anything else with the
14537 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14538 at run time. For example, the latter example above *cannot* be implemented
14539 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14540 evaluation time of the original SAVE_EXPR is not necessarily the same at
14541 the time the new expression is evaluated. The only optimization of this
14542 sort that would be valid is changing
14544 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14546 divided by 8 to
14548 SAVE_EXPR (I) * SAVE_EXPR (J)
14550 (where the same SAVE_EXPR (J) is used in the original and the
14551 transformed version). */
14553 int
14555 {
14563 {
14565 /* Bitwise and provides a power of two multiple. If the mask is
14566 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14569 /* FALLTHRU */
14582 {
14586 /* const_binop may not detect overflow correctly,
14587 so check for it explicitly here. */
14591 size_one_node,
14592 op1)))
14595 }
14599 /* Can't handle conversions from non-integral or wider integral type. */
14605 /* .. fall through ... */
14622 SIGNED);
14626 }
14627 }
14629 /* Return true if CODE or TYPE is known to be non-negative. */
14631 static bool
14633 {
14636 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14637 have a signed:1 type (where the value is -1 and 0). */
14640 }
14642 /* Return true if (CODE OP0) is known to be non-negative. If the return
14643 value is based on the assumption that signed overflow is undefined,
14644 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14645 *STRICT_OVERFLOW_P. */
14647 bool
14650 {
14655 {
14657 /* We can't return 1 if flag_wrapv is set because
14658 ABS_EXPR<INT_MIN> = INT_MIN. */
14662 {
14665 }
14672 strict_overflow_p);
14674 CASE_CONVERT:
14675 {
14680 {
14683 strict_overflow_p);
14685 {
14689 strict_overflow_p);
14690 }
14691 }
14693 {
14696 strict_overflow_p);
14700 }
14701 }
14706 }
14708 /* We don't know sign of `t', so be conservative and return false. */
14710 }
14712 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14713 value is based on the assumption that signed overflow is undefined,
14714 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14715 *STRICT_OVERFLOW_P. */
14717 bool
14720 {
14725 {
14730 strict_overflow_p)
14732 strict_overflow_p));
14734 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14735 both unsigned and at least 2 bits shorter than the result. */
14739 {
14744 {
14748 }
14749 }
14754 {
14755 /* x * x is always non-negative for floating point x
14756 or without overflow. */
14760 {
14765 }
14766 }
14768 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14769 both unsigned and their total bits is shorter than the result. */
14773 {
14792 {
14802 }
14803 }
14809 strict_overflow_p)
14811 strict_overflow_p));
14822 strict_overflow_p)
14824 strict_overflow_p));
14831 strict_overflow_p);
14834 }
14836 /* We don't know sign of `t', so be conservative and return false. */
14838 }
14840 /* Return true if T is known to be non-negative. If the return
14841 value is based on the assumption that signed overflow is undefined,
14842 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14843 *STRICT_OVERFLOW_P. */
14845 bool
14847 {
14852 {
14864 strict_overflow_p)
14866 strict_overflow_p));
14870 }
14871 /* We don't know sign of `t', so be conservative and return false. */
14873 }
14875 /* Return true if T is known to be non-negative. If the return
14876 value is based on the assumption that signed overflow is undefined,
14877 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14878 *STRICT_OVERFLOW_P. */
14880 bool
14883 {
14886 {
14906 /* Always true. */
14910 /* sqrt(-0.0) is -0.0. */
14914 strict_overflow_p);
14951 /* True if the 1st argument is nonnegative. */
14953 strict_overflow_p);
14956 /* True if the 1st OR 2nd arguments are nonnegative. */
14958 strict_overflow_p)
14960 strict_overflow_p)));
14963 /* True if the 1st AND 2nd arguments are nonnegative. */
14965 strict_overflow_p)
14967 strict_overflow_p)));
14970 /* True if the 2nd argument is nonnegative. */
14972 strict_overflow_p);
14975 /* True if the 1st argument is nonnegative or the second
14976 argument is an even integer. */
14981 strict_overflow_p);
14984 /* True if the 1st argument is nonnegative or the second
14985 argument is an even integer valued real. */
14987 {
14988 REAL_VALUE_TYPE c;
14989 HOST_WIDE_INT n;
14994 {
14995 REAL_VALUE_TYPE cint;
14999 }
15000 }
15002 strict_overflow_p);
15006 }
15008 type);
15009 }
15011 /* Return true if T is known to be non-negative. If the return
15012 value is based on the assumption that signed overflow is undefined,
15013 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15014 *STRICT_OVERFLOW_P. */
15016 static bool
15018 {
15024 {
15026 {
15030 /* If the initializer is non-void, then it's a normal expression
15031 that will be assigned to the slot. */
15035 /* Otherwise, the initializer sets the slot in some way. One common
15036 way is an assignment statement at the end of the initializer. */
15038 {
15046 else
15048 }
15052 strict_overflow_p);
15055 }
15058 {
15064 arg0,
15065 arg1,
15066 strict_overflow_p);
15067 }
15071 strict_overflow_p);
15074 strict_overflow_p);
15077 strict_overflow_p);
15082 }
15084 /* We don't know sign of `t', so be conservative and return false. */
15086 }
15088 /* Return true if T is known to be non-negative. If the return
15089 value is based on the assumption that signed overflow is undefined,
15090 set *STRICT_OVERFLOW_P to true; otherwise, don't change
15091 *STRICT_OVERFLOW_P. */
15093 bool
15095 {
15102 {
15109 strict_overflow_p);
15115 strict_overflow_p);
15124 }
15127 {
15135 strict_overflow_p);
15140 strict_overflow_p);
15153 }
15154 }
15156 /* Return true if `t' is known to be non-negative. Handle warnings
15157 about undefined signed overflow. */
15159 bool
15161 {
15168 "determining that expression is always "
15170 WARN_STRICT_OVERFLOW_MISC);
15172 }
15175 /* Return true when (CODE OP0) is an address and is known to be nonzero.
15176 For floating point we further ensure that T is not denormal.
15177 Similar logic is present in nonzero_address in rtlanal.h.
15179 If the return value is based on the assumption that signed overflow
15180 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15181 change *STRICT_OVERFLOW_P. */
15183 bool
15186 {
15188 {
15191 strict_overflow_p);
15194 {
15200 strict_overflow_p));
15201 }
15206 strict_overflow_p);
15210 }
15213 }
15215 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
15216 For floating point we further ensure that T is not denormal.
15217 Similar logic is present in nonzero_address in rtlanal.h.
15219 If the return value is based on the assumption that signed overflow
15220 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15221 change *STRICT_OVERFLOW_P. */
15223 bool
15225 tree type,
15226 tree op0,
15228 {
15231 {
15235 {
15236 /* With the presence of negative values it is hard
15237 to say something. */
15244 /* One of operands must be positive and the other non-negative. */
15245 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15246 overflows, on a twos-complement machine the sum of two
15247 nonnegative numbers can never be zero. */
15249 strict_overflow_p)
15251 strict_overflow_p));
15252 }
15257 {
15259 strict_overflow_p)
15261 strict_overflow_p))
15262 {
15265 }
15266 }
15275 {
15278 }
15285 {
15289 /* When both operands are nonzero, then MAX must be too. */
15291 strict_overflow_p))
15294 /* MAX where operand 0 is positive is positive. */
15296 strict_overflow_p);
15297 }
15298 /* MAX where operand 1 is positive is positive. */
15303 {
15307 }
15312 strict_overflow_p)
15314 strict_overflow_p));
15318 }
15321 }
15323 /* Return true when T is an address and is known to be nonzero.
15324 For floating point we further ensure that T is not denormal.
15325 Similar logic is present in nonzero_address in rtlanal.h.
15327 If the return value is based on the assumption that signed overflow
15328 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15329 change *STRICT_OVERFLOW_P. */
15331 bool
15333 {
15336 {
15341 {
15350 /* For objects in symbol table check if we know they are non-zero.
15351 Don't do anything for variables and functions before symtab is built;
15352 it is quite possible that they will be declared weak later. */
15354 {
15360 else
15362 }
15364 /* Function local objects are never NULL. */
15371 /* Constants are never weak. */
15376 }
15384 {
15388 }
15393 }
15395 }
15397 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15398 attempt to fold the expression to a constant without modifying TYPE,
15399 OP0 or OP1.
15401 If the expression could be simplified to a constant, then return
15402 the constant. If the expression would not be simplified to a
15403 constant, then return NULL_TREE. */
15405 tree
15407 {
15410 }
15412 /* Given the components of a unary expression CODE, TYPE and OP0,
15413 attempt to fold the expression to a constant without modifying
15414 TYPE or OP0.
15416 If the expression could be simplified to a constant, then return
15417 the constant. If the expression would not be simplified to a
15418 constant, then return NULL_TREE. */
15420 tree
15422 {
15425 }
15427 /* If EXP represents referencing an element in a constant string
15428 (either via pointer arithmetic or array indexing), return the
15429 tree representing the value accessed, otherwise return NULL. */
15431 tree
15433 {
15437 {
15439 tree index;
15440 tree string;
15445 else
15446 {
15450 /* Optimize the special-case of a zero lower bound.
15452 We convert the low_bound to sizetype to avoid some problems
15453 with constant folding. (E.g. suppose the lower bound is 1,
15454 and its mode is QI. Without the conversion,l (ARRAY
15455 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15456 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15462 }
15475 }
15477 }
15479 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15480 an integer constant, real, or fixed-point constant.
15482 TYPE is the type of the result. */
15484 static tree
15486 {
15490 {
15492 {
15499 }
15506 {
15507 FIXED_VALUE_TYPE f;
15512 /* Propagate overflow flags. */
15516 }
15520 }
15523 }
15525 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15526 an integer constant or real constant.
15528 TYPE is the type of the result. */
15530 tree
15532 {
15536 {
15538 {
15539 /* If the value is unsigned or non-negative, then the absolute value
15540 is the same as the ordinary value. */
15544 /* If the value is negative, then the absolute value is
15545 its negation. */
15546 else
15547 {
15552 }
15553 }
15559 else
15565 }
15568 }
15570 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15571 constant. TYPE is the type of the result. */
15573 static tree
15575 {
15579 }
15581 /* Given CODE, a relational operator, the target type, TYPE and two
15582 constant operands OP0 and OP1, return the result of the
15583 relational operation. If the result is not a compile time
15584 constant, then return NULL_TREE. */
15586 static tree
15588 {
15591 /* From here on, the only cases we handle are when the result is
15592 known to be a constant. */
15595 {
15599 /* Handle the cases where either operand is a NaN. */
15601 {
15603 {
15631 }
15634 }
15637 }
15640 {
15644 }
15646 /* Handle equality/inequality of complex constants. */
15648 {
15659 else
15661 }
15664 {
15671 {
15683 }
15686 }
15688 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15690 To compute GT, swap the arguments and do LT.
15691 To compute GE, do LT and invert the result.
15692 To compute LE, swap the arguments, do LT and invert the result.
15693 To compute NE, do EQ and invert the result.
15695 Therefore, the code below must handle only EQ and LT. */
15698 {
15703 }
15705 /* Note that it is safe to invert for real values here because we
15706 have already handled the one case that it matters. */
15710 {
15713 }
15715 /* Compute a result for LT or EQ if args permit;
15716 Otherwise return T. */
15718 {
15721 else
15723 }
15724 else
15730 }
15732 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15733 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15734 itself. */
15736 tree
15738 {
15739 /* If the expression does not have side effects then we don't have to wrap
15740 it with a cleanup point expression. */
15744 /* If the expression is a return, check to see if the expression inside the
15745 return has no side effects or the right hand side of the modify expression
15746 inside the return. If either don't have side effects set we don't need to
15747 wrap the expression in a cleanup point expression. Note we don't check the
15748 left hand side of the modify because it should always be a return decl. */
15750 {
15757 }
15760 }
15762 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15763 of an indirection through OP0, or NULL_TREE if no simplification is
15764 possible. */
15766 tree
15768 {
15770 tree subtype;
15778 {
15781 /* *&CONST_DECL -> to the value of the const decl. */
15784 /* *&p => p; make sure to handle *&"str"[cst] here. */
15786 {
15790 else
15792 }
15793 /* *(foo *)&fooarray => fooarray[0] */
15796 && (!in_gimple_form
15798 {
15808 }
15809 /* *(foo *)&complexfoo => __real__ complexfoo */
15813 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15816 {
15820 }
15821 }
15825 {
15831 {
15832 tree op00type;
15836 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15839 {
15851 }
15852 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15855 {
15859 }
15860 /* ((foo *)&fooarray)[1] => fooarray[1] */
15863 {
15873 }
15874 }
15875 }
15877 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15880 && (!in_gimple_form
15882 {
15883 tree type_domain;
15893 NULL_TREE);
15894 }
15897 }
15899 /* Builds an expression for an indirection through T, simplifying some
15900 cases. */
15902 tree
15904 {
15912 }
15914 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15916 tree
15918 {
15923 else
15925 }
15927 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15928 whose result is ignored. The type of the returned tree need not be
15929 the same as the original expression. */
15931 tree
15933 {
15939 {
15950 else
15956 {
15972 }
15977 }
15978 }
15980 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
15982 tree
15984 {
15990 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15991 have to do anything. Only do this when we are not given a const,
15992 because in that case, this check is more expensive than just
15993 doing it. */
15995 {
16000 }
16002 /* If divisor is a power of two, simplify this to bit manipulation. */
16004 {
16006 {
16020 }
16021 else
16022 {
16023 tree t;
16029 }
16030 }
16031 else
16032 {
16037 }
16040 }
16042 /* Likewise, but round down. */
16044 tree
16046 {
16053 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
16054 have to do anything. Only do this when we are not given a const,
16055 because in that case, this check is more expensive than just
16056 doing it. */
16058 {
16063 }
16065 /* If divisor is a power of two, simplify this to bit manipulation. */
16067 {
16068 tree t;
16072 }
16073 else
16074 {
16079 }
16082 }
16084 /* Returns the pointer to the base of the object addressed by EXP and
16085 extracts the information about the offset of the access, storing it
16086 to PBITPOS and POFFSET. */
16088 static tree
16091 {
16092 tree core;
16093 machine_mode mode;
16095 HOST_WIDE_INT bitsize;
16099 {
16104 }
16105 else
16106 {
16110 }
16113 }
16115 /* Returns true if addresses of E1 and E2 differ by a constant, false
16116 otherwise. If they do, E1 - E2 is stored in *DIFF. */
16118 bool
16120 {
16134 {
16144 }
16146 {
16147 /* If only one of the offsets is non-constant, the difference cannot
16148 be a constant. */
16150 }
16151 else
16156 }
16158 /* Simplify the floating point expression EXP when the sign of the
16159 result is not significant. Return NULL_TREE if no simplification
16160 is possible. */
16162 tree
16164 {
16169 {
16205 {
16208 {
16210 /* Strip copysign function call, return the 1st argument. */
16216 /* Strip sign ops from the argument of "odd" math functions. */
16218 {
16222 }
16224 }
16225 }
16230 }
16232 }
16234 /* Return OFF converted to a pointer offset type suitable as offset for
16235 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
16236 tree
16238 {
16240 }
16242 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16243 tree
16245 {
16248 }
16250 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
16251 tree
16253 {
16256 }